Scipedia: Documents published in 2014

Best options for regulating air transport's full climate impact from an economic and environmental point of view - Main results from DLR research project AviClim

Scipedia content — Thu, 28 Jan 2021 17:49:15 +0100

Im Rahmen der Veroffentlichung werden die wesentlichen Ergebnisse des BMBF-geforderten Projekts "AviClim" vorgestellt.

A clustering approach to assess the travel time variability of arterials

Scipedia content — Thu, 28 Jan 2021 17:47:14 +0100

TRB 2014 - 93rd Transportation Research Board Annual Meeting, WASHINGTON DC, ETATS-UNIS, 12-/01/2014 - 16/01/2014; The travel time variability may significantly influence the driver's route choice. Estimating travel time reliability is thus really appealing to urban infrastructure managers. This could provide better information to drivers, encourage their reassignment on the network, and optimize its use. In this paper, we study any arterial in under-saturated conditions with known fixed-time traffic signals. The kinematic wave model is chosen to simply represent traffic dynamics. A semi-analytical (grid-free) method is applied to determine the separation between vehicle groups at each signal of the arterial. The main contribution of this paper is to present an aggregated diagram that describes the functioning of this arterial. It graphically provides the direct assessment of vehicle travel times with respect to their departure and the traffic flow. This tool only depends on signal settings and is cyclic and invariant for fixed-time signals. We show how to use this diagram to generate probabilistic travel time distributions when some input parameters are uncertain. Furthermore, this diagram appears insightful when the traffic flow is not accurately known.

Multiple Obstacle Detection and Tracking using Stereo Vision: Application and Analysis

Scipedia content — Thu, 28 Jan 2021 17:36:44 +0100

International audience; Vision systems provide a large functional spectrum for perception applications and, in recent years, they have demonstrated to be essential in the development of Advanced Driver Assistance Systems (ADAS) and Autonomous Vehicles. In this context, this paper presents an on-road objects detection ap-proach improved by our previous work in defining the traffic area and new strategy in obstacle extraction from U-disparity.Then, a modified particle filtering is proposed for multiple object tracking . The perception strategy of the proposed vision-only detection system is structured as follows : First, a method based on illuminant invariant image is employed at an early stage for free road space detection. A convex hull is then constructed to generate a region of interest (ROI) which includes the main traffic road area. Based on this ROI, an U-disparity map is built to characterize on-road obstacles. In this approach, connected regions extraction is applied for obstacles detection instead of standard Hough Transform. Finally, a modified particle filter framework is employed for multiple targets tracking based on the former detection results. Besides, multiple cues, such as obstacle's size verification and combination of redundant detections, are em-bedded in the system to improve its accuracy. Our experimental findings demonstrates that the system is effective and reliable when applied on different traffic video sequences from a public database.

About the Balázs Mór Plan - or a Sustainable Urban Mobility Plan for Budapest

Scipedia content — Thu, 28 Jan 2021 17:30:42 +0100

Presentation on the Academic Transition Platform #1 (titled Research on Sustainability Transitions in Budapest) of the ARTS (Accelerating Transitions) EU FP7 project Szent István University, Gödöllő, 19 September 2014."/p" "p"

Scalable reactive vehicle-to-vehicle congestion avoidance mechanism

Scipedia content — Thu, 28 Jan 2021 17:30:10 +0100

The increasing popularity and acceptance of VANETs will make the deployment of autonomous vehicles easier and faster since the VANET will reduce dependence on expensive sensors. Many useful applications will be possible with the usage of VANETs, which will improve the safety and quality of trips for the owners of these vehicles. One of these applications is the avoidance of traffic congestion by smart dynamic rerouting. For scalability, current cloud-based solutions, like Google Maps traffic, update congestion levels after a time interval rather than providing real-time measurements. In this paper, we introduce a vehicle-to-vehicle congestion avoidance mechanism, which detects real-time congestion levels and reroutes vehicles accordingly to minimize their trip times. Our system is highly distributed and is, therefore, not subjected to the limitations of centralized congestion avoidance mechanisms. We show via simulation that our system can significantly decrease the trip times of vehicles as well as the average car density on the map. Our proposed system, with its checkpoint and offline path generation approaches, is more responsive to local congestion level changes and computationally less complex for least congested route calculations than state-of-the-art congestion avoidance mechanisms.

Real time alpha-fairness based traffic engineering

Scipedia content — Thu, 28 Jan 2021 17:17:27 +0100

SDN traffic engineering is used to assign bandwidth to flows. Classic traffic engineering algorithms are well understood however implementations of these algorithms typically take seconds or even minutes to execute. These long execution times force traffic engineering to be used as an off-line tool. We demonstrate a traffic engineering algorithm equivalent to these classic algorithms that executes in millisecond times, allowing traffic engineering to be used as an on-line tool -- much as shortest path computations are used in today's routers.

Isolating Different Factors Affecting Travel Time Reliability in an Observational Before/After Study

Scipedia content — Thu, 28 Jan 2021 17:16:47 +0100

It is increasingly recognized that travel time reliability is important to travellers and goods, and hence there is an increasing demand to include reliability in the evaluation and appraisal of transport projects and programs, as a separate factor in its own right. A number of the policy options already in use as congestion mitigation policies have also positive impacts on the travel time reliability. It is therefore important to evaluate impacts of any remedial action separately both for average travel time (congestion) and for variability of that travel time (reliability). The impacts are generally assessed with an observational before/after study. As many things, independent from the system to be assessed, change between the periods before and after the installation of the system, observational before/after studies take also into account a reference site, where the effect of these changes is identified. In a previous paper Bhouri and Aron, (2013) presented the reliability impacts of a managed lane case consisting in a Dynamic Hard Shoulder Running (HSR) during rush hours on a French urban motorway. The study was conducted by comparing reliability indicators based on data collected in 2002 before the implementation of the system and in 2006 after this implementation. Jacques Chirac, former president of France, launched in 2003 an important campaign for road safety and against speeding. This modified the travel time distribution, differently according to the lane. As reliability is based on the percentiles (and not only on averages), it was necessary, in order not to confound the effect of this campaign with the HSR effect, to develop the observational before/after study method for determining that time effect by level of travel time: to do this, the before and after travel time distributions of the reference site are established, then their difference is analyzed as a function of the travel time, taking into account the percentiles. This method and the results are presented in this paper.

Document type: Conference object

Detection of water leakage in buried pipes using infrared technology; A comparative study of using high and low resolution infrared cameras for evaluating distant remote detection

Scipedia content — Thu, 28 Jan 2021 17:09:45 +0100

Water is one of the most precious commodities around the world. However, significant amount of water is lost daily in many countries through broken and leaking pipes. This paper investigates the use of low and high resolution infrared systems to detect water leakage in relatively dry countries. The overall aim is to develop a non-contact and high speed system that could be used to detect leakage in pipes remotely via the effect of the change in humidity on the temperature of the ground due to evaporation. A small scale experimental test rig has been constructed to simulate water leakage in The Great Man- Made River Project in Libya, taking into consideration the dryness level of the desert sand and the scaled dimensions of the system. The results show that the infrared technology is an effective technology in detecting water leakage in pipes. The low resolution system has been found as valuable as the high resolution system in detecting water leakage. The results indicate the possibility of distant remote detection of leakage in water systems using infrared technologies which could be mobilised using drones, helium balloons, aeroplanes or other similar technologies.

Applying cross-channel user experience design theory to practice : A case study of a public transportation company in Sweden

Scipedia content — Tue, 26 Jan 2021 18:28:16 +0100

The emergence of digital technology, social media and ubiquitous computing in the 21stcentury changed customer behavior and created new possibilities, but also challenges, forcompanies offering their services. The new customer generation is more tech-savvy thanever before, and therefore places higher demands on companies to have well-designed experienceswith services that can be consumed through various channels. This study investigatesthese service environments to see if they are actively shaped to cross-channel ecosystemsby the companies or if the companies react to the demands of their customers. Furthermore,the goal of this thesis is to find out how the current theory of cross-channel userexperience can assist in formulating design strategies for service ecosystems. To determinethis, the authors conducted a theoretical analysis of the current IS literature and created,based on that, a cross-channel user experience design framework. Within a case study of aSwedish transportation company, company and user interviews, direct observations of theavailable service artifacts, analysis of documentation, and the design of the user journeyswere executed to assess the as-is ecosystem. On the basis of these results, it was proventhat cross-channel ecosystems are shaped based on user demands. The created frameworkwas applied to formulate a language of critique of the cross-channel user experience designof the underlying case study, and the framework was proven to be applicative to practiceafter adjusting it to its final version.

Environmental sustainability assessment of soybean and palm biodiesel systems : a life-cycle approach

Scipedia content — Tue, 26 Jan 2021 18:27:47 +0100

Tese de doutoramento em Sistemas Sustentáveis de Energia apresentada à Faculdade de Ciências e Tecnologia da Universidade de Coimbra Em Portugal mais de 50% do biodiesel é produzido a partir de óleo de palma e soja importados. O crescimento mundial do consumo destes óleos vegetais para a produção de biocombustíveis, tem vindo a ser acompanhado por uma crescente preocupação relativa aos seus potenciais impactes ambientais, nomeadamente os impactes associados às práticas agrícolas e aos efeitos da expansão das áreas de cultivo. Esta tese tem como objetivo avaliar a sustentabilidade ambiental do biodiesel produzido a partir de soja e palma cultivados na América do Sul. A investigação é desenvolvida e implementada para várias cadeias de produção de biodiesel contribuindo assim para a modelação de ciclo de vida (CV) de cadeias multifuncionais de sistemas de bioenergia. Os aspetos críticos relacionados com a modelação de CV são avaliados através de uma análise de cenários. O modelo e inventário de CV são desenvolvidos para três cadeias de produção: A) biodiesel produzido em Portugal a partir de óleo de palma importado da Colômbia, B) biodiesel produzido em Portugal a partir de soja importada do Brasil e Argentina e C) biodiesel produzido no Brasil e em Portugal a partir de soja cultivada em quatro estados brasileiros (Mato Grosso, Goiás, Paraná e Rio Grande do Sul). A influência do local onde ocorre a extração do óleo e a produção do biodiesel de soja é também analisada. As fases de CV do biodiesel incluídas nesta investigação são: as alterações do uso do solo (AUS), o cultivo, a extração e tratamento do óleo, a produção do biodiesel e o transporte de produtos. É realizada uma análise de sensibilidade a diferentes abordagens para lidar com a multifuncionalidade na cadeia de produção de biodiesel. Dois métodos (ReCiPe e CML) foram adotados na avaliação de impactes de CV do biodiesel, sendo que os impactes relacionados com a toxicidade são avaliados através da utilização dos métodos ReCiPe e USEtox. Os efeitos da utilização de diferentes cenários de produção de biodiesel ao longo do seu CV são avaliados: AUS definidas com base na conversão de diferentes usos do solo em plantações de soja ou palma, utilização de vários fertilizantes azotados no cultivo de palma, diferentes sistemas de cultivo de soja (mobilização completa, mobilização nula e sementeira direta), gestão do biogás produzido no tratamento dos efluentes na unidade de extração de óleo de palma (libertado para a atmosfera ou capturado) e transporte de soja (diferentes distancias e tipos de veículos). As emissões relacionadas com as AUS são também calculadas com base em dados históricos da expansão da área cultivada com palma na Colômbia (1990-2010) e com soja nos quatro estados brasileiros analisados (1985-2006). As emissões de azoto (N2O, NH3 e NO3-) decorrentes do cultivo são calculadas através de duas abordagens (IPCC Tier 1 e modelos baseados em dados específicos dos locais). Os resultados demonstram a importância das AUS na intensidade de GEE do biodiesel, verificando-se porém uma grande variabilidade nos resultados: a intensidade de GEE é elevada quando florestas são convertidas em plantações de soja ou palma e é bastante baixa ou negativa quando culturas anuais são convertidas em plantações de palma e pastagens/savanas degradadas são convertidas em plantações de soja. Diferentes resultados são obtidos quando se utilizam dados históricos relativos à expansão das áreas de soja e palma, sendo que neste caso a intensidade de GEE calculada para o biodiesel de palma é mais baixa do que para o biodiesel de soja (a palma é uma cultura perene, com elevado potencial para armazenar carbono). Os impactes ambientais do biodiesel são altamente influenciados pelas práticas agrícolas e de produção adotadas ao longo do seu CV. O método adotado na avaliação dos impactes ambientais também influencia significativamente os resultados. Relativamente ao cultivo da soja, os mais impactes baixos foram obtidos para os sistemas de cultivo com mobilização reduzida ou sementeira direta, sendo que no cultivo da palma os resultados variam para os diferentes fertilizantes utilizados dependendo das categorias de impacte. Diferentes resultados foram obtidos com as duas abordagens de cálculo das emissões de azoto decorrentes do cultivo. A intensidade de GEE do cultivo da palma e soja é altamente influenciada pelas emissões de N2O, que por sua vez variam significativamente dependendo dos parâmetros utilizados no seu cálculo. Os impactes ambientais da extração de óleo de palma variam bastante e dependem da gestão do biogás produzido no tratamento dos efluentes. Verificou-se que os impactes ambientais do biodiesel de soja são altamente influenciados pelas emissões decorrentes do transporte. Relativamente ao efeito da multifuncionalidade nos resultados, verificou-se que este é consideravelmente maior para o biodiesel de soja do que para o biodiesel de palma. Os impactes ambientais calculados com alocação baseada no teor energético e nos preços dos coprodutos são similares, sendo ambos superiores aos resultados calculados com base em alocação mássica. O método da substituição é também adotado e demonstra que os resultados dependem muito do cenário considerado (qual o produto evitado). A redução das emissões de GEE do biodiesel de soja e palma relativamente ao combustível fóssil de referência é avaliada de forma a apoiar as empresas portuguesas no cálculo e cumprimento dos critérios de sustentabilidade estabelecidos na Directiva Europeia das Energias Renováveis (RED). Os resultados variam significativamente e na maioria dos cenários analisados são diferentes das emissões de GEE apresentadas na RED. A grande variabilidade de resultados apresentada nesta tese demonstra que a avaliação dos impactes ambientais do biodiesel é problemática e que cada caso deve ser analisado individualmente. FCT SFRH/BD/60328/2009

Automatic vehicle detection and occlusion handling at road intersections

Scipedia content — Tue, 26 Jan 2021 18:22:29 +0100

Vision based intelligent transport system applications are extensively utilized and researched in recent years. Several applications with tracking, classiﬁcation and counting functionalities are used for automatization of trafﬁc management. Work in this thesis aims to provide an accurate vehicle detection method for improving performance of these tasks. Vehicle detection starts with detection of moving objects, using a background subtraction algorithm. Then, accuracy of the foreground mask is improvedusingashadowdetectionalgorithm. Occlusionsaredetectedfrombothgeometrical properties of blobs in binary mask, and associations between objects from consecutive observations. A segmentation method based on the assumptions on objectgeometryunderocclusionisproposedandimplemented,todetectvehiclesunder occlusion correctly. Proposed solution is tested on several videos collected from different intersections. Results indicate a signiﬁcant improvement in performance compared to the existing methods in literature. M.S. - Master of Science

Generic Model Predictive Control Framework for Advanced Driver Assistance Systems

Scipedia content — Tue, 26 Jan 2021 18:13:13 +0100

This thesis deals with a model predictive control framework for control design of Advanced Driver Assistance Systems, where car-following tasks are under control. The framework is applied to design several autonomous and cooperative controllers and to examine the controller properties at the microscopic level and the resulting traffic flow characteristics at the macroscopic level. The results give new insights into impacts of ADAS on traffic flow characteristics.

A study on software defined networks : traffic engineering

Scipedia content — Tue, 26 Jan 2021 18:10:15 +0100

Sustainable public transportation: quantifying the benefits of sustainable Bus Rapid Transit systems

Scipedia content — Tue, 26 Jan 2021 18:05:16 +0100

Transportation in densely populated areas is becoming increasingly problematic. Congestion, air pollution, accident-related fatalities and time wasted in traffic are only a few of issues associated urban transportation. Personal transportation is expected to increase by 63% total, where car traffic is expected to increase by 67% and railway traffic – by 80% during the period from 2006 to 2050. With that kind of dynamic, reaching the currently set sustainability goals is impossible. This raises the need for introducing sustainable public transportation solutions. Defining sustainability in the context of public transportation and taking into account the case-specific differences that affect the definition is an important step in this process. Quantification and the use of calculation tools for sustainability impact assessment are important for discussing the subject in concretized terms. Public transportation involves a multitude of stakeholders that each have their own responsibility areas. Since public transportation systems are ultimately a collective effort, every stakeholder has to partake in this endeavor on their corresponding level of responsibility. Socioeconomic criteria are an integral part of sustainability impact analysis, since it puts technical transport-related calculations into a broader context that goes beyond the transport sector. This is a qualitative applied study of Scania’s efforts in developing calculation models to facilitate leading the dialogue by providing quantitative evidence during the early stages of their solution sales process. In this report, the methodology for sustainability impact assessment, traffic planning and socioeconomic calculations are studied and applied on the case of Scania, where a holistic calculation tool is developed for the company. Bus Rapid Transit systems have been proven to be effective, sustainable solutions of public transportation in several regions. The vehicle fleet is an important component within the BRT system, which is why calculation tools for analysis of sustainability impacts of BRT systems have high strategic significance for Scania. By providing quantitative evidence of the benefits of sustainable public transportation, the company is going to be able to gain additional market shares while simultaneously promoting sustainable urban public transportation. Transport i tätbefolkade områden blir alltmer problematiskt. Trängsel, luftföroreningar, olycksrelaterade dödsfall och tid bortslösad i trafiken är bara några av de typiska problemen som medföljer modern stadstrafik. Personlig transporter förväntas öka med 63% totalt, där biltrafiken förväntas öka med 67% och järnvägstrafiken - med 80% under perioden från 2006 till 2050. Om den typen av dynamik fortsätter, är det omöjligt att nå de i dagsläget satta hållbarhetsmålen. Detta skapar ett behov av att införa hållbara kollektivtrafiklösningar. Att definiera hållbarhet inom kollektivtrafiksammanhanget med hänsyn till fallspecifika aspekter som påverkar definitionen är ett viktigt steg i denna process. Kvantifiering och användning av beräkningsverktyg för att göra hållbarhetsbedömningar är viktiga för att diskutera ämnet i konkretiserade termer. Transportsektorn involverar en mängd aktörer som var och en har sina egna ansvarsområden. Eftersom kollektivtrafiksystem i slutändan definieras av samtliga aktörernas kollektiva insats, är det upp till varje aktör att engagera sig i processen på deras motsvarande ansvarsnivå. Samhällsekonomiska kriterier är en viktig del av hållbarhetskonsekvensbeskrivning, eftersom det sätter tekniska transportrelaterade beräkningar i ett bredare sammanhang som sträcker sig utöver transportsektorn. Detta är en kvalitativ tillämpad studie av Scanias arbete inom utveckling av beräkningsmodeller som ska underlätta att föra dialogen genom att tillhandahålla kvantitativa bevis i ett tidigt skede i försäljningsprocessen av kollektivtrafiklösningar. I denna rapport, är metodiken för hållbarhetskonsekvensbeskrivning, trafikplanering och samhällskonomiska beräkningar studerad och tillämpad på fallet Scania, där ett helhetsberäkningsverktyg har utvecklats för företaget. Bus Rapid Transit-system har visat sig vara effektiva och hållbara lösningar för kollektivtrafiken i flera regioner. Fordonsparken är en viktig komponent i BRT-systemet, vilket är anledningen till att beräkningsverktyg för analys av hållbarhetseffekterna av BRT-system har hög strategisk betydelse för Scania. Genom att uttrycka fördelarna med hållbar kollektivtrafik i kvantifierade termer kommer företaget att kunna få ytterligare marknadsandelar och samtidigt främja hållbar storstadskollektivtrafik.

Kentiçi Raylı Sistemlerde Hat Bakımlarının Planlanması, Yönetimi Ve Risk Değerlendirmesi

Scipedia content — Tue, 26 Jan 2021 17:59:48 +0100

Tez (Yüksek Lisans) -- İstanbul Teknik Üniversitesi, Fen Bilimleri Enstitüsü, 2015

Thesis (M.Sc.) -- İstanbul Technical University, Instıtute of Science and Technology, 2015

Ülkemizde özellikle İstanbul başta olmak üzere son yıllarda köylerden kentlere doğru göçlerin olması sebebiyle günlük hayatta ulaşım problemleri görülmektedir. Her geçen gün insanların trafikte geçirdiği zaman artmaktadır. Bu sebeple yerel yönetim yetkilileri kentiçi raylı sistem yatırımlarına verdikleri önemi artırmışlardır. Bu tez çalışması iki kısımdan meydana gelip ilk kısmında yurtdışı örneklerinin de verildiği kentiçi raylı sistem hat bakımlarının planlanmasından ve yönetiminden bahsedilmiş olup ortaya daha somut veriler koymak adına Başakşehir Metro hattı ele alınmıştır. Demiryolu bakım çalışmalarının planlamasının nasıl yapıldığından, sınırlayıcı koşullardan, çakışan bakımların ötelenmesinden bahsedilmiştir. Tezde ele alınan tüm bakımlar, lokasyonlar ve sayısal veriler tamamen somut veriler olup şahsım tarafından hazırlanmıştır ve halen aynı bakım planlaması üzerinden hat bakım çalışmaları gerçekleştirilmektedir. 2 yılı planlı olmak üzere 3 yıldır hat bakımlarının yapıldığı Başakşehir metro hattında başarılı bir planlama neticesinde bakımların aksamadan ve özenle yapılması sayesinde yolculara güvenli ve konforlu hizmet verilmektedir. Ayrıca planlı bakımlar hattın ekonomik ömrünü de uzatmaktadır. Tez çalışmamızın ikinci kısmında ise kentiçi raylı sistemlerin hat bakım çalışmaları neticesinde ortaya çıkabilecek tehlike ve risklere karşı alınması gereken tedbirlerden bahsedilmiştir. Bu tedbirleri belirlerken bütün bakım çalışmaları tek tek ele alınmış olup her biri ile ortaya çıkabilecek riskler ve mevcut tedbirler gözönünde bulundurulmuştur. Risk değerlendirmesi yaparken Fine-Kinney methodu kullanılmıştır. Risk değerlendirmesi sonucu sürdürülecek tedbir çalışmaları için yetkili personeller belirlenmiştir. Bakım çalışmalarında olduğu gibi risk değerlendirmesi sonucu ortaya çıkan sonuç raporu da halen Başakşehir Metro Hattında aktif olarak kullanılmaktadır. Üzerinde çalışılan risk değerlendirmesi ile kentiçi raylı sistemler hat bakım çalışmalarında yaşanabilecek kaza oranını minimuma indirgemek hedeflenmektedir.

In our country especillay in Istanbul there have been some transport problems in daily life in recent years due to the migration from villages to cities. The time that people spend in traffic has been increasing day by day. Therefore, the local government officials have increased the importance which they give to investment in urban railway system. Because urban railway systems are more ecological, safer and more comfortable than the other public trasnports. Also people can go anywhere they want just in time as it has no relation to traffic. Now, there are 4 metro lines and 2 tram lines in İstanbul and their total length is 120 km. On the other hand 2 new metro lines’ construction continue. And also many metro lines’ projects have being designed. Aim for the year 2023, total urban railway systems lenght is 630 km in İstanbul. If it will be accomplished, İstanbul is going to have one of the longest urban railway system all over the world. By the way, the number of passengers will increase 5-6 times. In this thesis, which consists of two parts in which in the first part planning of urban railway system maintenance and management have been mentioned with the examples from overseas, Başakşehir Metro Line has been studied in order to put some concrete data. And also mentioned that how it made the planning of rail maintenance work, what are the limiting conditions, how it made the displacement of maintenance works. All maintenance, locations and quantitive datas discussed in the thesis are completely concrete and prepared by myself and also track maintenance work has still been carried out on the same planning of maintenance. For a better understanding of track maintenance planning, the management, station and tunnel structures and the connection systems, superstructure and geometric features of Başakşehir Metro Line have been mentioned primarily making the definition of tram, light rail transit and metro. In order to make a planning of urban railway system, a wide knowledge of line maintenance is required. While making a planning of maintenance, the maintenance time, maintenance intervals, the number of employees needed for this maintenance work and how many people are in need for how many hours are determined. Afterwards, the capacity of man-hour in one-week period that the mainteance unit has is determined and the maintenance planning is made beginning with the shortest period one. The longer maintenance period which coincides with another maintenance in the same week is made one week before or after. How to use some maintenace equipments and the analysis of them on computer environment has been also mentioned while mentioning about the methods of maintenance. Especially emphasizing the line geometric measuring devices, how to interpret the graphics has been mentioned. The reason why we emphasize this device is that thanks to this device we can see lots of measurement which can be made with hands on computer environment at the same time. As a result of good planning, safe and comfortable service has been offered to passengers for 3 years-2 years of planned- thanks to regular and careful maintenance on Başakşehir Metro Line. Also planned maintenance prolong the economic life of track. On the other hand, poor lines increases the cost of management distrupting the profile of trains' wheel. In the second part of the thesis, some precautions that must be taken against probable danger and risks that may occur as a result of urban railway systems maintenance work have been issued. All maintenance work in determininng these measures have been discussed individually with each of the risks that may arise and measures that have been taken into account. While assesing risk, other risk assesment methods such as Matris, FMEA, FTA, ETA, HAZOP have been mentioned and Fine-Kenney method has been used. The reason why we've used Finne-Kinney method is that many line maintenance works have been made in different periods and every maintenance work has different timetable. Not only mainteance works must be done by experts but also risk assesment must be done by experts. For this reason, foreign service recruitment for the risk assesment of line maintenace is not appropriate. Providing the service of Kartal-Kadıköy Metro Line in 2013 and Başakşehir Metro Line in 2014, there has been increase in the number of work accidents in urban railway system in Istanbul. However, as a result of effective occupational health and safety studies applied in Başakşehir Metro Line, the increase in the number of work accident in maintenance unit has been prevented. This result has been got in the light of the past and current data of work accidents. In 2014, there has been only one work accident in Başakşehir Metro Line. Just as in the maintenance work, the final report in consequence of risk assesment has still been used actively on Başakşehir Metro Line. This risk assessment which is about the maintenance works in urban railwasy systems aims to mimimize the accident rate.

Yüksek Lisans

M.Sc.

Upravljanje putanjama vazduhoplova u kontroli letenja na pre-taktičkom i taktičkom nivou

Scipedia content — Tue, 26 Jan 2021 17:59:19 +0100

Global air traffic demand is continuously increasing, and it is predicted to be tripled by 2050. The need for increasing air traffic capacity motivates a shift of ATM towards Trajectory Based Operations (TBOs). This implies the possibility to design efficient congestion-free aircraft trajectories more in advance (pre-tactical, strategic level) reducing controller’s workload on tactical level. As consequence, controllers will be able to manage more flights. Current flow management practices in air traffic management (ATM) system shows that under the present system settings there are only timid demand management actions taken prior to the day of operation such as: slot allocation and strategic flow rerouting. But the choice of air route for a particular flight is seen as a commercial decision to be taken by airlines, given air traffic control constraints. This thesis investigates the potential of robust trajectory planning (considered as an additional demand management action) at pre-tactical level as a mean to alleviate the en-route congestion in airspace. Robust trajectory planning (RTP) involves generation of congestion-free trajectories with minimum operating cost taking into account uncertainty of trajectory prediction and unforeseen event. Although planned cost could be higher than of conventional models, adding robustness to schedules might reduce cost of disruptions and hopefully lead to reductions in operating cost. The most of existing trajectory planning models consider finding of conflict-free trajectories without taking into account uncertainty of trajectory prediction. It is shown in the thesis that in the case of traffic disturbances, it is better to have a robust solution otherwise newly generated congestion problems would be hard and costly to solve. This thesis introduces a novel approach for route generation (3D trajectory) based on homotopic feature of continuous functions. It is shown that this approach is capable of generating a large number of route shapes with a reasonable number of decision variables. Those shapes are then coupled with time dimension in order to create trajectories (4D)... Globalna potražnja za vazdušnim saobraćajem u stalnom je porastu i prognozira se da će broj letova biti utrostručen do 2050 godine. Potreba za povećanjem kapaciteta sistema vazdušnog saobraćaja motivisala je promene u sistemu upravljanja saobraćajnim tokovima u kome će u budućnosti centralnu ulogu imati putanje vazduhoplova tzv. “trajectory-based” koncept. Takav sistem omogućiće planiranje putanja vazduhoplova koje ne stvaraju zagušenja u sistemu na pre-taktičkom nivou i time smanjiti radno opterećenje kontrolora na taktičkom nivou. Kao posledica, kontrolor će moći da upravlja više letova nego u današnjem sistemu. Današnja praksa upravljanja saobraćajnim tokovima pokazuje da se mali broj upravljačkih akcija primenjuje pre dana obavljanja letova npr.: alokacija slotova poletanja i strateško upravljanje saobraćajnim tokovima. Međutim izbor putanje kojom će se odviti let posmatra se kao komercijalna odluka aviokompanije (uz poštovanje postavljenih ograničenja od strane kontrole letenja) i stoga je ostavljen na izbor avio-kompaniji. Većina, do danas razvijenih, modela upravljanja putanjama vazduhoplova ima za cilj generisanje bez-konfliktnih putanja, ne uzimajući u obzir neizvesnost u poziciji vazduhoplova. U ovoj doktorskoj disertaciji ispitivano je planiranje robustnih putanja vazduhoplova (RTP) na pre-taktičkom nivou kao sredstvo ublažavanja zagušenja u vazdušnom prostoru . Robustno upravljanje putanjama vazduhoplova podrazumeva izbor putanja vazduhoplova sa minimalnim operativnim troškovima koje ne izazivaju zagušenja u vazdušnom prostoru u uslovima neizvesnosti buduđe pozicije vazduhoplova i nepredviđenih događaja. Iako predviđeni (planirani) operativni troškovi robustnih putanja mogu u startu biti veći od operativnih troškova bez-konfliktnih putanja, robusnost može uticati na smanjenje troškove poremećaja putanja jer ne zahteva dodatnu promenu putanja vazduhplova radi izbegavanja konfliktnih situacija na taktičkom nivou. To na kraju može dovesti i do smanjenja stvarnih operativnih troškova. U tezi je pokazano, da je u slučaju poremećaja saobraćaja bolje imati robustno rešenje (putanje), jer novo-nastali problem zagušenosti vazdušnog prostora je teško i skupo rešiti...

Development of an Interdisciplinary Simulation Environment for Traffic Safety Modeling

Scipedia content — Tue, 26 Jan 2021 17:52:50 +0100

Safety research and modeling has traditionally been divided into two separate realms – that of the vehicle and that of the road. Because crashes are caused by a variety of factors – the driver, the vehicle, and the road – and their interactions, it is ideal to look at the larger picture of transportation safety. Modeling is a useful test bed for new technologies and improvements; and greater fidelity in safety modeling will allow designers to see the potential impact of an infrastructure or vehicular change before implementing it. To make the greatest impact, civil and mechanical engineers must work together to capture the entirety of the transportation system, tying together elements of traffic flow, driver behavior, and vehicle dynamics. For this project, made possible by a University of Virginia Seed grant, an interdisciplinary model for was developed testing safety technology by linking VISSIM, a civil engineering traffic flow simulator, and MADYMO, a mechanical engineering vehicle dynamics simulator. Traffic conflicts were chosen as a surrogate for crashes due to the limitations of simulation and the rareness of crashes. The outputs of the model are the number and type of conflicts along with severity metrics and the probabilities of different injury types. Only rear-end crashes have been studied so far, but the model could be extended to cover other crash types and other explanatory variables. The model was validated on crash data from Route 50 in northern Virginia before being used for a demonstration on testing the efficacy of forward collision warning, pre-crash braking, and autonomous pre-crash braking. It is demonstrated that existing models can be tied together to examine transportation safety in terms of the roadway, vehicles, and driver and test new technologies and infrastructure improvements.

Vaness: DNS for nomadic users in vehicular networks

Scipedia content — Tue, 26 Jan 2021 17:52:37 +0100

Mestrado em Engenharia de Computadores e Telemática Vehicular networks, also known as VANETs, are an ad-hoc network formed by vehicles and road-side units. Nowadays they have been attracting big interest both from researchers as from the automotive industry. With the upcoming of automotive specific operating systems and self-driving cars, the use of applications on vehicles and the integration with common mobile devices is becoming a big part of VANETs. Although many advances have been made on this field, there is still a big discrepancy between the communication layer services provided by VANETs and the user level services, namely those accessible through mobile applications on other networks and technologies. Users and developers are accustomed to user-to-user or user-tobusiness communication without explicit concerns related with the available communication transport layer. Such is not possible in VANETs since people may use more than one vehicle. However, to send a message to a specific user in these networks, there is a need to know the ID of the vehicle where the user is, meaning that there is a lack of services that map each individual user to VANETs endpoint (vehicle identification). This dissertation work proposes VANESS, a naming service as a resource to support user-to-user communication within a heterogeneous scenario comprising typical ISP scenario and VANETs focused on mobile devices. The proposed system is able to map the user to an end point either locally (i.e. there is not internet connection at all), online (i.e. system is not in a vehicular network but has direct internet connection) and using a gateway (i.e. the system is in a vehicular network where some of the nodes have internet access and will act as a gateway). VANESS was fully implemented on android OS with results proving his viability, and partially on iOS showing its multiplatform capabilities. As redes veiculares, também conhecidas por VANETs, são redes ad-hoc formadas por veículos e road-site units. Hoje em dia estas redes têm atraído bastante interesse tanto por parte de investigadores como da indústria automóvel. Com o aparecimento de sistemas operativos especificamente dedicados a automóveis e carros de condução autónoma, o uso de aplicações em veículos e a integração com dipositivos móveis está-se a tornar uma parte cada vez maior nas VANETs. Apesar dos grandes avanços tecnológicos realizados nesta área, ainda existe uma grande discrepância entre os serviços de camada de comunicação disponibilizados pelas VANETs e os serviços ao nível do utilizador, nomeadamente aqueles acessíveis a partir de aplicações móveis noutras redes e tecnologias. Os utilizadores e programadores estão habituados a interações utilizador-utilizador ou utilizadorempresa sem preocupações explícitas sobre a camada de transporte em causa. Isto não é possível em redes VANETs, uma vez que cada pessoa pode usar vários veículos. No entanto, uma mensagem para ser enviada para um utilizador específico através destas redes precisa do indentificador do veículo onde tal utilizador está, ou seja, existe uma falta de serviços que mapeiem cada utilizador individual a nós na VANET (identificação do veículo). O trabalho desta dissertação propõe o sistema VANESS, um serviço de nomes (naming service) disponibilizado como um recurso para suporte a comunicação utilizador-a-utilizador num cenário heterogéneo englobando o típico ISP e VANETs focadas em dispositivos móveis. O sistema proposto é capaz de mapear um utilizador a um veículo tanto localmente (i.e. não existe ligação à internet), online (i.e. o sistema não está numa rede veicular mas tem acesso direto à internet) e usando um gateway (i.e. o sistema está numa rede veicular onde algum nó tem acesso à internet e irá servir como gateway). VANESS foi integralmente implementado em Android OS, onde os resultados dos testes mostram que é um sistema viável, e parcialmente em iOS mostrando a sua capacidade para multi-plataformas.

Study of the performance of an electric vehicle

Scipedia content — Tue, 26 Jan 2021 17:49:54 +0100

This study presents the model of a basic electric vehicle as well as some theoretical concepts used for its development. The simulation assumes a specific driving cycle, a DC motor, the motor controllers combined with a proportional-integral controller and the electric battery. The results confirm that it is a reliable model although it could be improved by complementing it with other technologies. The model has been created using Matlab/Simulink software.

Variación del nivel de servicio de las vías urbanas en una zona con tarifa de cobro por congestión para autos particulares

Scipedia content — Tue, 26 Jan 2021 17:48:51 +0100

La presente tesis de maestría contiene el desarrollo de una investigación que permite determinar el grado de mejora futuro en la movilidad de una zona de alta congestión vehicular para cualquier ciudad, a través de la medición de la variación del nivel de servicio en las vías urbanas comparando al escenario base con un escenario hipotético en donde hay una implantación de un sistema de cobro por congestión para autos particulares, como medida para desestimular el uso del auto, reducir los flujos vehiculares en las vías en las horas pico y aumentar así los índices de movilidad. La investigación aporta una metodología para determinar la variación del nivel de servicio a partir de la velocidad de circulación de los vehículos en las vías urbanas de una zona congestionada ante la implantación de una tarifa de cobro por congestión. Para ello, se utilizó como herramienta el software de macromodelación PTV Visum 14, por medio del cual se realizó simulaciones tanto para el escenario base como para el escenario hipotético de cobro, con el cual se obtiene las velocidades en cada uno de los segmentos de vías de la zona en estudio. El nivel de servicio se determinó, utilizando los procedimientos de análisis recomendados por el Manual de Capacidad Vial Americano HCM – 2000, en su referente a las vías urbanas. La metodología de investigación, se aplicó para la zona céntrica de la ciudad de Medellín, en donde a partir del análisis e insumos de información secundaria fue posible definir un escenario hipotético de cobro por congestión que se comparó con un escenario base. Los resultados obtenidos indicaron para el escenario hipotético de cobro un 15% de aumento de la velocidad media de circulación en las vías internas y una disminución del 5% de la velocidad media para las vías del anillo circundante (libre de cobro); en cuanto al nivel de servicio de las vías, en la zona interna aproximadamente 2,5 Km (14%) de vías mejoran el nivel de servicio pasando de un nivel de servicio menos favorable a uno más favorable, pese a esta variación, el 40% de vías (7,4 Km) continúan en niveles de servicio desfavorables (D, E y F). Por otro lado, se evaluó el tiempo de viaje en la red para los dos escenarios, obteniéndose que el tiempo medio de recorrido por cada auto en las vías internas se reduce de 3,00 minutos/Km en el escenario base a 2,54 minutos/Km en el escenario con cobro; para toda la red interna y todos los autos se tiene una reducción del 41%, pasando de 5.471,23 a 3.217,87 horas de viaje, lo que en beneficios sociales representados en ahorro del tiempo para todos los usuarios viajantes significa un ahorro de aproximadamente 67,8 Millones de pesos diarios que equivale aproximadamente 16.360 Millones de pesos al año; en cambio para el anillo vial circundante se tiene que los tiempos de viaje totales del anillo se incrementan en un 6%, pasando de 6.741,40 a 7.175,19 horas. El estudio también permitió identificar que el alto grado de congestión de la zona centro de Medellín no sólo es causa del uso del auto particular, sino de otros modos motorizados como las motos, el taxi, y los buses; además, de la invasión de vías y espacios públicos por el comercio informal, por parqueos indebidos y zonas de acopio que reducen la capacidad de las vías. Todos estos resultados permitieron concluir que el escenario de cobro por congestión en la forma como fue evaluado sería una medida que proporciona buenos resultados para mejorar la movilidad del centro de la ciudad de Medellín, pudiendo llegar a obtener mejores resultados con algunos cambios y medidas adicionales como incluir también una tarifa para restringir el uso exagerado de las motos, implementar la reorganización y modernización del transporte público colectivo, mejorar la gestión y control del tránsito mediante políticas de uso y racionalización del espacio público y aparcamientos; políticas de promoción del transporte no motorizado, entre otras. Abstract: this master's thesis contains the development of a research to determine the level of future improvement in the mobility of a high vehicular congestion zone for some city, by measuring the variation in the level of service in comparing urban roads the base with a hypothetical scenario where there is an implementation of a congestion charging system for private cars, as a measure to discourage car use, reduce traffic flows on roads during peak hours and increase mobility rates scenario. The research provides a methodology to determine the variation in the level of service from the speed of vehicles on urban roads in a congested area before the implementation of a congestion charge fee. To this, it was used as tool software macro-model PTV Visum 14, whereby simulations for both the baseline and for the hypothetical scenario collection was performed, which speeds is obtained in each of the segments of roads of the study area. The service level was determined using the analysis procedures recommended by the American Highway Capacity Manual HCM - 2000, as regards urban roads. The research methodology was applied to the central area of the city of Medellin, where from analysis of secondary information and input was possible to define a hypothetical scenario that congestion charging was compared to a baseline scenario. The results showed for the hypothetical scenario of charging 15% increase in the average velocity at the domestic level and a decrease of 5% of the average speed of the surrounding ring roads (free of charge); in the level of service roads in the inner area about 2,5 km (14%) of roads improve the level of service from a level of service less favorable to one more favorable, despite this variation, 40 % of roads (7,4 km) are still in unfavorable operating levels (D, E and F). On the other hand, was assessed travel time on the network for the two scenarios, obtaining the average travel time for each car at the domestic level is reduced to 3,00 minutes/Km in the baseline scenario to 2,54 minutes/Km on stage with collection; for the entire internal network and all cars have a reduction of 41% from 5471,23 to 3217,87 hours of travel, which represented in social benefits in time savings for all travelers it means users save approximately 67,8 million pesos per day or approximately 16360 million pesos a year; in exchange for the surrounding ring road must be total travel time of the ring is increased by 6%, from 6741,40 to 7175,19 hours. The study also identified that the high level of congestion in the downtown area of Medellin is not only because of the use of the private car, but in other ways as motorized bikes, taxis, and buses; Furthermore, the invasion of roads and public spaces for informal trade, for improper parking and storage areas that reduce the ability of the tracks. These results concluded that the scenario of congestion charging in the form as assessed would be a measure that gives good results for improving the mobility of downtown Medellin, but could do better with some additional changes and measures as also include a fee to restrict the excessive use of motorcycles, implement the reorganization and modernization of public transport, improve traffic management and control through use policies and rationalization of public space and parking; policies to promote non-motorized transport, among others.

Kombine Taşımacılık Ve Türkiye Uygulamaları

Scipedia content — Tue, 26 Jan 2021 17:45:00 +0100

Tez (Yüksek Lisans) -- İstanbul Teknik Üniversitesi, Fen Bilimleri Enstitüsü, 2015

Thesis (M.Sc.) -- İstanbul Technical University, Instıtute of Science and Technology, 2015

Ulaştırma, ekonominin ve toplumsal gelişmenin temel öğesidir. Ulaştırma, modern ekonomilerde önemli bir faktördür. Ulaşım talebi gün geçtikçe artmaktadır. Ulaşım talebinin artışı yeni altyapı inşaatı ve pazarlara açılma ile karşılanamaz. Taşıma sisteminin, büyüme ve sürdürülebilir kalkınma taleplerini karşılamak için optimize edilmesi gerekmektedir. Modern bir taşıma sistemi ekonomik, sosyal ve çevre açısından sürdürülebilir olmalıdır. Ulaştırma sektörüne yönelik yapılan planlarda ekonomi, göz önünde bulundurulmalıdır. Küreselleşme ile ulaşım, haberleşme ve teknolojideki gelişmeler sonucunda üretim ve pazarlama uluslararası hale gelerek, ürünlerin güvenli, hızlı ve ekonomik bir şekilde teslim edilmesi önem kazanmıştır. Küreselleşme ile birlikte kombine taşımacılık daha da önemli hale gelmiştir. Pazarlama açısından düşünüldüğünde birçok şirket çevreye duyarlı taşımacılık alternatifi olduğundan kombine taşımacılığı tercih etmektedir. Ülkemizin Asya ile Avrupa arasında bir köprü konumunda olması, üç tarafının denizlerle çevrili ve önemli geçiş koridorlarında bulunması nedeniyle lojistik üs olma potansiyeli bulunmaktadır. Bu amaç doğrultusunda hazırlanan tez çalışması, sekiz ana bölümden oluşmaktadır. Birinci bölümde konuya giriş yapılmış olup kombine taşımacılığın gelişim süreci ele alınmış ve tezin amacı ortaya konulmuştur. İkinci bölümde taşıyıcının türüne göre karayolu, demiryolu, havayolu, denizyolu, iç suyolu, boru hattı taşımacılığı ve taşıma türüne göre tek türlü, çok türlü, türler arası, kombine taşımacılık olmak üzere ulaştırma sistemleri açıklanmıştır. Üçüncü bölümde kombine taşımacılığın amacı, kombine taşımacılığın temel bileşenleri ve konteyner taşımacılığı, araç sırtında taşımacılık, bi-modal taşımacılık olmak üzere kombine taşımacılık türleri anlatılmıştır. Dördüncü bölümde ulaştırma türü seçim kriterleri ele alınarak, karayolu, demiryolu, denizyolu, havayolu taşıyıcı türlerinin üstünlükleri ve zayıf yönleri ulaştırma türünün belirlenmesinde etkili olan maliyet, hız, güvenilirlik, esneklik, güvenlik, kapasite, yakıt tüketimi, çevre gibi faktörler göz önünde bulundurularak incelenmiştir. Beşinci bölümde Avrupa Birliği’nde kombine taşımacılık politikaları, ulaştırma sistemlerinin durumu, Trans-Avrupa ulaştırma ağları, Pan-Avrupa ulaştırma koridoru, Avrupa Kafkasya Asya ulaştırma koridoru gibi Avrupa ulaştırma ağları ve Avrupa’daki ana uluslararası bağlantılar üzerinde yapılan kombine taşımacılık incelenmiştir. Avrupa’daki başarılı kombine taşımacılık örnekleri verilerek, kombine taşımacılığın CO² emisyonu ve yakıt tüketimi üzerindeki etkileri belirtilmiştir. Altıncı bölümde Türkiye’de ulaştırma sistemlerinin durumuna, demiryolu ile konteyner taşıması, denizyolu ile konteyner taşıması, Ro-Ro, feribot taşıması olmak üzere kombine taşımacılık uygulamalarına ve Türkiye’deki limanların sorunlarına değinilmiştir. Türkiye’nin lojistik bir üs olma yolunda ilerlemesini sağlayacak ve kombine taşımacılığı destekleyecek olan lojistik köy kavramı, lojistik köyün konumuna etki eden faktörler ve lojistik köy faaliyetleri açıklanmış, Avrupa’daki başarılı lojistik köy örneklerinden yararlanılarak Türkiye’deki lojistik köyler incelenmiştir. Yedinci bölümde Türkiye’nin kombine taşımacılıktaki durumu değerlendirilmiş kuvvetli, zayıf yönler, fırsatlar ve tehditler belirtilmiştir. Türkiye’de yük taşımacılığında karşılaşılan sorunlardan yola çıkılarak, Türkiye’deki uygulamalar değerlendirilmiş ve yapılan tespitler sonucunda konu ile ilgili öneriler sunulmuştur. Sekizinci ve son bölümde ise Türkiye’de kombine taşımacılık konusunda yapılan tespitler tavsiye niteliğinde ele alınmıştır.

Transportation is an essential element of economic and social development. Transportation is a major factor in modern economies. Transport demand is increasing day by day. Increase in transport demand cannot be met only with the construction of new infrastructure and open markets. The transport system must be optimized in order to meet growth and sustainable development demands. A modern transport system must be economical, social, and environmental sustainability. Economy should be taken into consideration in the plans made for the transport sector. The impact of globalization on transportation, production and marketing as a result of advances in communications and technology by becoming international, rapid, safe and economic products delivery is getting important. Combined transportation has become more important after globalization. Combined transport, which contribute to making an ideal of transport logistics, by using the advantageous aspects of the different transport modes. In this context, the intermodal or combined transport is considered a factor that promotes international trade all countries to prepare policies in this direction and create incentive mechanisms. In terms of technological and operational features, multimodal, intermodal or combined transport, the same load, from producers to consumers shipment or vice versa focuses on the use of two or more modes of transport due to economic reasons or physical-geographical conditions. The combined transport concept is based on the seventeenth century. A French writer described that his horse-drawn carriage boarded on a barge and moved on Rhone River for 400 km, to avoid the rough road route. This can be an example of the primitive roll-on/roll-off (Ro-Ro) transport. Then, in 1830, horse-drawn carriage was carried on wagons. In addition to this, in the 1960s Ro-Ro transport has appeared in the Scandinavian countries in order to tourism. Before the First World War, road-rail-sea trimodal combined transport service between Paris and London was operated. The International Union of Combined Road-Rail Transport Companies is established on 23 October 1970 in Munich and then, in 1972 first international rolling road link was established between the cities of Cologne (Germany) and Verona (Italy). In 1987, Wabash National builds first RoadRailer trailer. Furthermore, combined transport become more preferable with the containerization. In 1792 boxes, which are resemble to the modern container, had been used for combined rail- and horse-drawn transport in England. Standardization of steel containers were developed in the 1950s by the US Armed Forces. In commercial maritime transportation in today's standard first move was made by American entrepreneur Malcolm McLean in 1956. The International Organization for Standardization (ISO) set standard sizes in 1961. Combined transport is organized by the Combined Transport Operator and under a contract called a Combined Transport Document, the load is delivered to the recipient's door on the door of the seller. Combined transport, is based on a single contract made with the combined transport operator and with this contract; gives for all process-related all responsibility to the operator. This property is the reason that combined transport the more preferred method than unimodal transport which require more than one contract at the delivery door-to-door transport. When considered in terms of marketing, many companies prefer combined transport which is environmentally friendly transportation alternative. Due to the fact that Turkey which is a bridge between Europe and Asia, surrounded by Marmara Sea, Black Sea and Mediterranean on three sides and on important transit corridor, our country has the potential to become a logistics center. The thesis prepared for this purpose consists of eight parts. The first part is made introduction to the subject dealt with in the process of development of combined transport and the purpose of the thesis is stated. In the second chapter of the thesis, firstly, transport systems is described according to the type of carrier including road, rail, air, sea, inland waterway, pipeline transport. Then, type of transport modes involving unimodal, multimodal, intermodal, combined transport is explained. In the third part, the purpose of combined transport, the basic components of combined transport involving transport vehicles, transport terminals, transport units, and types of combined transport including container transport, piggyback transport, and bimodal transport is expressed. In the fourth chapter, transportation mode selection criteria are explained. Parameters affecting on the transportation mode selection is stated that the performance parameters (transport time, frequency, reliability, capacity limits), cost parameters, quality of service (loss injury rate and management, communication, customer distribution and transport planning, flexibility) and general parameters (company structure and organization, government intervention and existing transportation facilities). Then, road, rail, sea, air, inland waterway transport types of strengths and weaknesses has been examined by considering factors such as cost, speed, reliability, flexibility, security, capacity, fuel consumption, environment that are effective in determining the mode of transport. In the fifth part, combined transport policy in the European Union, the situation of the transport system, the Trans-European transport networks, the Pan-European transport corridors, European transport networks such as TRACECA and combined transport on the main international connections in Europe were investigated. Giving examples of successful combined transport in Europe, the effects of combined transport on CO² emissions and fuel consumption is stated. In the sixth chapter, the situation of the road transport, railway transport, maritime transport, and airline transport in Turkey is analyzed. After that, combined transport applications in Turkey including the railway container transportation, container transportation by sea, Ro-Ro and ferry transport, and the port’s problems in Turkey were mentioned. After that, the concept of freight villages is described. The first freight villages were established in France especially Garonor and Sogaris. This village has been responding to the urban logistics policy criteria. Towards the end of the 1960s and logistics villages in the 1970s, rail-road intermodal terminals with the concept has emerged in Italy and Germany. In the 1980s and 1990s, the number of logistics villages in France, Germany, Italy, the Netherlands, Belgium and England have increased. And also, freight villages will play an important role in the supporting combined transport and providing progress towards becoming a logistic center of Turkey. In addition to this, factors affecting the location of the freight villages and their activities were described, and freight villages in Turkey were analyzed by using the example of successful freight villages in Europe in this part. In the seventh chapter, the situation of combined transportation in Turkey according to strength, weaknesses, opportunities and threats were evaluated. Starting from the problems encountered in the freight transport in Turkey, applications in Turkey were evaluated. Recommendations about highway, railway, road transportation, Ro-Ro transportation, ports, and freight villages, examining the construction of the continued and planned projects were presented on the subject as a result of determinations made. The eighth and final section, The determinations about combined transport in Turkey, made are specified in the advisory.

Yüksek Lisans

M.Sc.

Optimisation et gestion de l’incertitude du trafic aérien

Scipedia content — Tue, 26 Jan 2021 17:41:49 +0100

In this thesis, we investigate the issue of optimizing the aircraft operators' demand with the airspace capacity by taking into account uncertainty in air traffic management. In the first part of the work, we identify the main causes of uncertainty of the trajectory prediction (TP), the core component underlying automation in ATM systems. We study the problem of online parameter-tuning of the TP during the climbing phase with the optimization algorithm CMA-ES. The main conclusion, corroborated by other works in the literature, is that ground TP is not sufficiently accurate nowadays to support fully automated safety-critical applications. Hence, with the current data sharing limitations, any centralized optimization system in Air Traffic Control should consider the human-in-the-loop factor, as well as other uncertainties. Consequently, in the second part of the thesis, we develop models and algorithms from a network global perspective and we describe a generic uncertainty model that captures flight trajectories uncertainties and infer their impact on the occupancy count of the Air Traffic Control sectors. This usual indicator quantifies coarsely the complexity managed by air traffic controllers in terms of number of flights. In the third part of the thesis, we formulate a variant of the Air Traffic Flow and Capacity Management problem in the tactical phase for bridging the gap between the network manager and air traffic controllers. The optimization problem consists in minimizing jointly the cost of delays and the cost of congestion while meeting sequencing constraints. In order to cope with the high dimensionality of the problem, evolutionary multi-objective optimization algorithms are used with an indirect representation and some greedy schedulers to optimize flight plans. An additional uncertainty model is added on top of the network model, allowing us to study the performances and the robustness of the proposed optimization algorithm when facing noisy context. We validate our approach on real-world and artificially densified instances obtained from the Central Flow Management Unit in Europe.; Cette thèse traite de la gestion du trafic aérien et plus précisément, de l'optimisation globale des plans de vol déposés par les compagnies aériennes sous contrainte du respect de la capacité de l'espace aérien. Une composante importante de ce travail concerne la gestion del'incertitude entourant les trajectoires des aéronefs. Dans la première partie du travail, nous identifions les principales causes d'incertitude au niveau de la prédiction de trajectoires. Celle-ci est la composante essentielle à l'automatisation des systèmes de gestion du trafic aérien. Nous étudions donc le problème du réglage automatique et en-ligne des paramètres de la prédiction de trajectoires au cours de la phase de montée avec l'algorithme d'optimisation CMA-ES. La principale conclusion, corroborée par d'autres travaux de la littérature, implique que la prédiction de trajectoires des centres de contrôle n'est pas suffisamment précise aujourd'hui pour supporter l'automatisation complète des tâches critiques. Ainsi, un système d'optimisation centralisé de la gestion du trafic aérien doit prendre en compte le facteur humain et l'incertitude de façon générale. Par conséquent, la seconde partie traite du développement des modèles et des algorithmes dans une perspective globale. De plus, nous décrivons un modèle stochastique qui capture les incertitudes sur les temps de passage sur des balises de survol pour chaque trajectoire. Ceci nous permet d'inférer l'incertitude engendrée sur l'occupation des secteurs de contrôle par les aéronefs à tout moment. Dans la troisième partie, nous formulons une variante du problème classique du Air Traffic Flow and Capacity Management au cours de la phase tactique. L'intérêt est de renforcer les échanges d'information entre le gestionnaire du réseau et les contrôleurs aériens. Nous définissons donc un problème d'optimisation dont l'objectif est de minimiser conjointement les coûts de retard et de congestion tout en respectant les contraintes de séquencement aucours des phases de décollage et d'attérissage. Pour combattre le nombre de dimensions élevé de ce problème, nous choisissons un algorithme évolutionnaire multi-objectif avec une représentation indirecte du problème en se basant sur des ordonnanceurs gloutons. Enfin, nous étudions les performances et la robustesse de cette approche en utilisant le modèle stochastique défini précédemment. Ce travail est validé à l'aide de problèmes réels obtenus du Central Flow Management Unit en Europe, que l'on a aussi densifiés artificiellement.

Light a Spark! Addressing Barriers and Enablers to Increase Demand of Electric Vehicles in Southeast Sweden

Scipedia content — Tue, 26 Jan 2021 17:39:52 +0100

The Personal Transportation System safeguards peoples’ cultural understanding of freedom: to move individually without being dependent on others. However, the increasing number of private vehicles driven on fossil fuels contributes to unsustainability and one of the most urgent issues, climate change. The authors explored electric vehicles as an alternative to fossil fuel driven vehicles as a way of moving strategically towards sustainability in the Personal Transportation System. In order to increase demand of electric vehicles, barriers need to be overcome. The authors identified perceived barriers and enablers through literature review, interviews with automobile dealers and other stakeholders of the EV sector in Southeast Sweden, as well as through an electronic survey of individuals living in this region. The outcome of the thesis is a pilot strategy using behavior change tools from Community-Based Social Marketing in order to address the perceived barriers and enablers on the demand side of the electric vehicle market. With highly positive attitudes towards electric vehicles in Southeast Sweden, the strategy may be successful in the region; however, it needs to be combined with further measures on the supply side of the market which cannot be addressed with behavior change tools.

Autofly-aıd: Havada Çarpışmadan Kaçınma İçin Esnek Ve Uyarlamalı 4 Boyutlu Dinamik Rota Yönetimi İle Uçuş Karar Destek Sistemi

Scipedia content — Tue, 26 Jan 2021 17:39:23 +0100

Tez (Doktora) -- İstanbul Teknik Üniversitesi, Fen Bilimleri Enstitüsü, 2015

Thesis (PhD) -- İstanbul Technical University, Institute of Science and Technology, 2015

AUTOFLY-Aid olarak adlandırılan bu tez çalışması, dinamik 4-Boyutlu rota yönetimi ile çarpışmadan kaçınma ve verimli uçuş rotaları planlamaya yarayan yeni nesil uçuş karar destek algoritma ve cihazlarının geliştirilmesi ve kavramsal tasarımının gerçekleştirilmesini amaçlamıştır. Geliştirilen karar destek sistemleri halihazırda var olan kokpit içi çarpışmadan kaçınma sistemlerinin (bknz. TCAS) eksikliklerini gidermeyi vizyonlamanın ötesinde, uçuşta veri değişimi, sanal gerçeklik tabanlı karar destek, hızla değişen durumlar için otonom uçuş kontrolü sağlama gibi fonksiyonlara olanak sağlayan ek kavramsal aviyonikler ve prosedürler geliştirilmesi de amaçlanmıştır. AUTOFLY-Aid’in ana konseptleri; a) SESAR ve NextGen modernizasyonlarının 2020+ vizyonları ve ötesindeki havasahasının kokpit içerisinden algısının matematiksel olarak modellenmesi, b) anlık ve orta-mesafede kompozit bir hava sahasında hızla değişen durumlara karşı alternatifleriyle beraber uçulabilir rotalar ve manevralar üreten 4-boyutlu rota planlama algoritmalarının geliştirilmesi, c) değişen durumlarda pilota görsel anlama ve durumsal farkındalık kazandıracak sanal gerçeklik karar destek sistemleri, otonom uçuş kontrolü sağlama ve bunun gibi yenilikçi prosedürler içeren bu uçuş otomasyonu sistemlerinin Boeing 737-800 Uçuş Simülatörü içerisine entegrasyonu ve testlerinin yapılmasıdır. Tamamen merkezi olarak taktiksel seviyede uçuşa müdahale modelinden, daha etkin stratejik seviyede planlama yapma ve daha fazla otomasyon destekli ve daha aktif arayüzler içeren merkezcil olmaktan uzak taktik operasyonlar hem SESAR hem de NextGen gelecek paradigma değişimlerinde ana mesele olarak durmaktadır. Bu yeni nesil Hava Trafik Yönetimi (ATM) konseptleri “en iyi karar noktası”, “en iyi karar zamanı” ve “en iyi karar vericiyi” değerlendirilmesiyle insanın ATM sistemi içerisindeki rolünü ciddi şekilde değiştirecektir. Bu amaçlar doğrultusunda, AUTOFLY-Aid yerdeki hava trafik kontrolörünün bir takım iş yükü ve sorumluluklarını etkin bir şekilde kokpit içerisine taşımayı amaçlamıştır. Geliştirilmiş olan otomasyon sistemi sürekli olarak dinamik çevresel ve operasyonel değişkenleri izleyerek ya da yer sistemlerinden veri linkleri aracılığıyla toplayarak uçuş güvenliğini ve verimliliğini gözlemler ve dinamik uçuş rotası planlaması yapar. Bu sistem gerekli otomasyon seviyesini gerekli aksiyon sürelerini değerlendirerek “en iyi karar vericiyi”, “nerede insan iyi, nerede makina iyi” sorgusu yaparak belirler. Orta seviye güvenlik modunda, pilot görsel karar destek sistemlerini kullanarak (örneğin sanal tünel içerisinde uçuş) en üst seviye durumsal farkındalık ile güvenli ve verimli uçuşunu gerçekleştirebilmektedir. Bu görsel karar destek sunumları kokpitin kendi duyargaları ve yer-hava arası veri paylaşımları ile edindiği bilgilerin bileşkesinden elde edilmektedir. Eğer gerekli reaksiyon süresi izin verir ise, pilot bu göstergeler üzerinden alternatif rota planları üretebilir, sonuçları değerlendirebilir, tekrar planlama talep edebilir. Anlık bir tehdit algısı oluştuğunda (anlık reaksiyon gerekli olduğu ya da geç kalınan reaksiyon tespiti olduğunda) otomasyon sistemi potansiyel kritik problemi (havada çarpışma, yere çarpma vb.) çözmek amacıyla uçuş kontrolünü ele geçirebilmektedir. Bu hibrid yaklaşım gerekli aksiyon zamanları değerlendirmesi yaparak bu şekilde bir otonomi seviyesi geçişlerini kontrol edebilmektedir.

This thesis, namely, AUTOFLY-Aid Project, aims to develop and demonstrate novel flight deck automation support algorithms and tools for potential conflict avoidance and performance-optimal flight using "dynamic 4D trajectory management". The developed automation support system is envisioned not only to improve the primary shortcomings of existing on-board traffic collision avoidance systems (e.g. TCAS), but also to develop new conceptual add-on avionics and procedures enabling intent data exchange, decision support systems with augmented reality and flight control hand-over implementation in dynamically evolving scenarios. The main concepts which has been developed in AUTOFLY-Aid project are a) design and development of the mathematical models of the full composite airspace picture from the flight deck perspective, as seen/measured/informed by the aircraft flying in the sky of the SESAR and NextGen 2020+ vision and beyond, b) design and development of a dynamic 4D trajectory planning algorithm can generate at real-time flyable (i.e. dynamically and performance-wise feasible) alternative trajectories for both short-term and mid-term scale across the evolving stochastic composite airspace picture and c) development and testing of the automation support system on a Boeing 737-800 Flight Simulator with conceptual procedures, automated flight control implementations, and reality augmented based decision support demonstrations providing the flight crew with quantified and visual understanding of evolving situation. Evaluation from a purely centralized tactical intervention model towards a more strategic planning and progressive introduction of more autonomous and decentralized tactical operation with more proactive systems are key concepts in both NextGen and SESAR future ATM paradigm shift vision. Implementing of these new-generation ATM concepts will significantly change the human role in the ATM system by considering "best decision place", "best decision time" and "the best decision player". Through these objectives, AUTOFLY-Aid envisions to take some of the work off the controller by delegating some responsibility to flight decks in an efficient manner. The developed automation system offers persistent in-flight hazard and flight efficiency monitoring and tactical flight trajectory planning as a function of look-ahead time and dynamically changing environmental/operational conditions (and with uncertainty reduction in a feedback loop) obtained via both in-flight sense and ground-air data link. The automation system switches autonomy level according to the required response time in order to find "the best decision player" through asking "where are men better at, where are machines better at". In mid-term safety assurance mode, it is expected that pilot uses a visual decision support tools (e.g. tunnel-in-the-sky visualization) with fully situational awareness for safe and performance optimal flight. These visual advisories are generated by fusing all tactical level information feed from both on-board sensing and ground-air data/information exchange. If the reaction time permits, the system allows pilots to freely switch between the generated alternative plans, modify the solution or request re-planning. In any case of the immediate potential threat is detected (i.e. immediate response is required or late response is detected), the autonomous system may take over the flight control to solve safety-critical situation happening "almost surely" (e.g. midair collision, terrain collision etc.). This hybrid approach allows dynamic role assignment by switching between defined autonomy level modes in terms of the "required response time".

Doktora

PhD

Exploring the quality of crowd sourced data: A comparison and analysis of formal and informal school datasets from open and licenced sources

Scipedia content — Tue, 26 Jan 2021 17:38:47 +0100

Spatial data is becoming increasingly important to decision making in all areas of life, affecting all types of businesses and services, right down to individuals throughout our towns, cities and countryside. With the rise of Volunteered Geographic Information (VGI), government initiatives on making more data ‘open’ and the monopoly of formal spatial data providers, there are now many different choices about what source of spatial data is best suited to a particular task or activity. This paper explores the quality of a VGI data source, namely OpenStreetMap (OSM). It explores various aspects of quality by focusing on a range of Scottish school data, covering three local council areas. The data has been collected from a number of different sources - formal and informal; open and licenced. The aim is to ascertain how the datasets compare to each other, quantify their strengths and highlight any possible weaknesses. The results of this study show that to get a complete picture of schools in an area, no one dataset can be relied on alone. Each one has its positive and negative aspects. If VGI is to truly compete with established formal data providers, there needs to be more encouragement, help and guidance for contributors on adding metadata and attribution to the objects they draw, so that the data has the potential to be used for spatial analysis and research purposes.

Investigation of Business Models for Utilization of Electric Vehicles for Frequency Control

Scipedia content — Tue, 26 Jan 2021 17:25:51 +0100

the awareness of energy security and global warming is increasing, alternative technologies are being developed such as electric vehicles. In addition, the integration of a more sustainable energy system with renewable resources put a lot of pressure on the electricity system in terms of regulation power. This thesis has investigated and developed proposals of business models with electric vehicles, which by their construction can raise value for both customers and electricity companies. The development of the business models have been done using a model, which was based on the complexity of the frequency control market, the charging of vehicles and the behavior of the drivers. The proposed models address two types of customer segments; business and private customers. In addition, applying a perspective that includes active and non-active customers has segmented these further. Based on the assumptions in the thesis, the most promising area of interest is the non-active business customer, in this case, a car pool. This proposal was based on the simulation results together with an analysis of advantages and disadvantages with active and non-active customers. This proposal assumed that customers preferred to be non-active in order to maintain flexibility and freedom, which could be studied further by customer surveys.

Inequality in Accessibility to Amenities and Exposure to Hazards

Scipedia content — Tue, 26 Jan 2021 17:24:39 +0100

This dissertation proposes a heuristic theoretical framework for understanding dynamics that impact environmental health including social/built environmental settings, individual residents' behavioral patterns, location activity spaces (LAS), environmental quality, exposure, and health outcomes. I examined the relationships between factors included in the framework based on individuals' LASs, and represent a hypothetical geographic boundary in which an individual is expected to spend his/her time in daily life. In addition to the individual level exposure, I characterized built environmental quality for subsidized housing neighborhoods in Los Angeles and Orange Counties, which have not been the focus of previous affordable housing studies. In Chapter 2 and Chapter 4, I empirically demonstrated the framework for residents in neighborhoods near the Expo Right Rail Transit line and the Boyle Heights community in Los Angeles. With OLS regression analysis, I found that bigger LAS were associated with lower walkability, more non-residential land use, higher transit stop density, shorter length of residency, working out of home, and higher income. I examined the relationship between the probability of a census block group (BG) having at least one subsidized unit and associated BG built environmental qualities. Based on logistic regression models, I found that subsidized housing units tended to be located in BGs with better transit access, lower walkability, more mixed-use, and lower air pollution concentrations.

Analysis of transit bus weight characteristics in the Canadian prairie region

Scipedia content — Tue, 26 Jan 2021 17:24:24 +0100

Within the transit industry it is well known that transit buses have the potential to operate at weights that exceed vehicle weight limits. However, few attempts have been made to date to determine how often this occurs and to what degree. This research characterizes the current transit industry with respect to the regulatory environment, factors that have affected the weight of modern day transit buses, and methods for accommodating transit buses in pavement design. This research then develops and applies a methodology for calculating the in-service weights of standard 40-ft. transit buses using a combination of passenger characteristic data, transit bus curb weight data, and transit ridership data. The findings of this research suggest that the transit bus industry is in a state of competing interests. Weight estimates developed in this research identify that current transit bus models are unable to comply with vehicle weight limits in most jurisdictions even with no passengers on board. Further, these estimates indicate that transit buses have a significant impact on pavements – comparable to those of fully-loaded, five-axle semi-trucks on a per vehicle basis. To date this issue has been addressed in the Canadian Prairie Region by indefinitely granting transit buses overweight permits. However, based on the current state of the transit industry there is little incentive for transit agencies to operate lightweight transit buses and little incentive for transit bus manufacturers to produce lightweight transit buses in order to address pavement and regulatory concerns. Consequently, transit bus axle weight issues in the Canadian Prairie Region are expected to continue in the foreseeable future. October 2015

Analyzing the Effects of e-Freight within the Air Cargo Industry : A cross-sectional case study focusing on air carriers and freight forwarders in the U.S. and China

Scipedia content — Tue, 26 Jan 2021 17:20:10 +0100

This study aims to analyze the effects (e.g. changes of power and processes) of the e-freight initiative introduced by IATA on the air freight supply chain network by focusing on two specific cases within the U.S. and Chinese market. After identifying two representative cases (cross sectional), data was gathered using semi- structured interviews, additional data provided by the participants, as well as secondary data, such as annual reports and case studies. The findings are analyzed using key words and suitable categories. A power model based on the current situation of the air freight supply chain is developed by analyzing the circumstances while implementing e-AWB/e-freight. This model can be used to add to the existing gap within the present literature framework. Further, changes regarding the supply chain network, especially processes and information flow were identified. Lastly, mainly positive (e.g. increased sustainability of the transportation process) as well as some negative effects (e.g. investments of the dual process) are mentioned in a de- tailed manner. Limitations of the study include a research population of two major actors of the air freight supply chain network, as well as a theoretical framework primarily based on literature and the fact that the study focuses on a cross sectional time period. Future research would include an analysis of all involved actors, while including IATA as the trade association, of the air freight supply chain, and especially issues related to customs procedures. Also, a longitudinal study, a more in depth analysis of the power distribution and any related changes should be of interest.

Traffic simulation for traffic congestion problem of Fatih Sultan Mehmet Bridge of Istanbul Turkey

Scipedia content — Tue, 26 Jan 2021 17:19:39 +0100

Text in English; Abstract: English and Turkish Includes bibliographical references (leaves 48-49) x, 50 leaves On a regular day, almost 200,000 cars use Fatih Sultan Mehmet Bridge of Istanbul to commute between European and Asian side of the Bosporus. This enormous volume causes the traffic congestion to become a problem not only endemic to the bridge, but also cascading some major arterial roads of the city. This study includes a simulation model to analyze the traffic congestion problem in Fatih Sultan Mehmet Bridge of Istanbul. The main focus of this research are to identify the bottlenecks of the system, to discover vehicle behaviors in these bottlenecks, and to create a simulation model to predict the level of congestion on the bridge that will occur with different arrival rates of the vehicles. Our simulation analysis shows that even though there is no significant difference between the number of cars arriving to the bridge from both directions in the evening rush hour, when both directions on the bridge have four lanes (without any counter-flow lane), east direction (Europe-to-Asia) suffers more from traffic congestion due to lane merging taking place after the electronic toll collection (ETC) plazas. The analysis also suggests that a counter-flow lane in favor of the east (Europe-to-Asia) direction significantly improves the average number of cars congested at the entrance of the bridge. Ortalama bir günde İstanbul Boğazının Avrupa ve Asya yakası arasında seyahat etmek için neredeyse 200,000 araç Fatih Sultan Mehmet Köprüsünü kullanmaktadır. Bu miktarda araç sadece köprüde değil köprüye ulaşan ana arterlerde de trafik sıkışıklığı problemi oluşmasına neden olmaktadır. Bu çalışma Fatih Sultan Mehmet Köprüsündeki trafik sıkışıklığı probleminin analizi için oluşturulmuş bir simülasyon modelini içermektedir. Bu araştırmanın asıl odak noktası sistemin sahip olduğu darboğazların tespit edilmesi, araçların bu darboğazlardaki davranış biçimlerinin incelenmesi ve değişik araç geliş sıklıkları için trafik sıkışıklığı seviyesi tahmini yapılabilmesi için bir simülasyon modeli oluşturulmasıdır. Yapmış olduğumuz analizin önemli sonuçlarından bir tanesi köprünün her iki yakasına gelen araç sayısında önemli bir farklılık olamamasına rağmen akşam yoğunluğu saatlerinde her iki yöne 4 şerit ayrıldığında (ek şerit uygulaması olmadan) Doğu (Avrupa-Asya) yönüne giden araçlar trafik yoğunluğundan daha fazla etkilenmektedir. Bu yoğunluk farkı gişeler bölgesi sonrasındaki şerit birleşimi etkisinden kaynaklanmaktadır. Analizimizin önerisi Doğu yönüne (Avrupa-Asya) bir ek şerit verilerek köprü girişinde ortalama bekleyen araç sayısının azaltılması yönündedir.

Metro Depo Sahası Tasarım Ölçütleri Ve Tasarımı etkileyen Etkenlerin İncelenmesi

Scipedia content — Tue, 26 Jan 2021 17:19:21 +0100

Tez (Yüksek Lisans) -- İstanbul Teknik Üniversitesi, Fen Bilimleri Enstitüsü, 2015

Thesis (M.Sc.) -- İstanbul Technical University, Instıtute of Science and Technology, 2015

Metro depo sahasında; araçların park edilmesi, işletilmesi, temizliği, bakım ve onarımı, tamir ve yenilenmesi, günlük bakımı, malzemelerin sağlanması gibi gereksinimleri karşılayacak tesisler bulunmaktadır. Bu tesislerin tasarımı yapılarken dikkat edilmesi gereken birçok etken ve tasarım ölçütü vardır. Bu tez çalışmasında öncelikli olarak İstanbul’daki metro hatlarından ve bu metro hatlarının depo sahalarından söz edilmiştir. Ardından metro depo sahasının tanımı ve bileşenleri açıklanmış, metro depo sahası tasarımını etkileyen etkenler ve tasarım ölçütleri sıralanmıştır. Daha sonra İstanbul Üsküdar-Ümraniye-Çekmeköy metro hattı depo sahası anlatılarak, ihale dokümanındaki uygulamaya esas kesin proje tasarımı incelenmiş ve yeni bir metro depo sahası ön proje tasarımı geliştirilmiştir. Elde edilen sonuçlar belirlenerek, metro depo sahası tasarımı yapılırken göz önünde bulundurulması gereken yeni öneri ve yaklaşımlar getirilmiştir. Metro depo sahası tasarımını etkileyen etkenler; konum ve yer seçimi, işletme, atölye binası ve bakım hizmetleri, araç park hatları, metro araç özellikleri, karayolu bağlantısı, şehir ve çevre etkileşimi, metro depo sahası bağlantı yolu, güvenlik, elektromekanik sistemler, altyapı, üstyapı ve hat geometrisi olarak sıralanabilir. Tasarım ölçütleri olarak, metro hattı tasarım ölçütleri, atölye yapıları tasarım ölçütleri, çevresel gürültü ve çevresel titreşim ölçütleri dikkate alınmalıdır. Depo sahasının konumu ve yeri seçilirken, hizmet edeceği metro hatlarına yakın olmasına dikkat edilmelidir. Seçilen arazinin, istenilen tesislerin yerleşimine uygun koşullarda, büyüklükte olması ve topoğrafyasının engebesiz olması gerekir. İşletme için kumanda ve kontrol merkezinin bulunduğu, bütün metro hattı ve depo sahasının denetiminin yapıldığı bir işletme binası tesis edilmelidir. İşletme binası ve tesisleri tasarlanırken, tüm işletme senaryolarına uygun ve elverişli yerleşimler yapılmalıdır. Atölye binası ve bakım hizmetleri, bütün araçlara servis sağlayabilecek kapasiteye göre belirlenir. Çift taraftan girişli atölye binası tasarımı daha çok tercih edilse de, arazinin durumuna göre tek taraftan girişli atölye binası da tasarlanabilir. Metro depo sahasının ana amacı metro araçlarına hizmet vermek olduğu için, araç özelliklerine göre bütün tesisler şekillenir. Araçların statik ve dinamik gabarisi, uzunlukları ve kullanılabildikleri hat geometrisi özelliklerine göre, dolanım hatlarının, atölye hatlarının, park hatlarının ve tesislerin yerleşimi yapılır. Karayolu bağlantıları sayesinde depo sahası çalışanlarının ulaşımı, malzeme temini ve metro araçlarının depo sahasına ulaşımı sağlanabilir. Acil durumlarda karayolunu kullanacak acil durum ekiplerinin araçlarına uygun olarak karayolu tasarımlarının yapılmasına dikkat edilmelidir. Şehir ile uyum içerisinde, gürültü ve titreşimlerin denetim altında tutulduğu, atıkların toplanması ve bertarafı için çevreci tesislerin kurulduğu, kirlenmiş suların arıtıldığı ve çevreci bir drenaj sisteminin bulunduğu bir depo sahası tasarımı yapılarak çevre etkileri azaltılmalıdır. Bağlantı yolu; metro hattı ile depo sahası arasındaki ulaşım güvenilirliğini sağlamalı, bir aksaklık durumunda farklı güzergahlarla ulaşım devam etmelidir. Depo sahasının güvenliği için giriş ve çıkışlar denetim altında tutulmalı, izinsiz girişleri engellemek için duvar ve çitlerle arazinin çevresi korunmalıdır. Can güvenliği için insanların araç hatlarına geçişi sınırlandırılmalıdır. Araçların cer gücünü karşılayacak cer trafo merkezi ve uygun katener sistemleri tasarlanıp, araçları denetlemek ve trafik akışını sağlamak için sinyalizasyon donanımları tesis edilmelidir. Altyapı için uygun malzeme seçilerek, gerekli olan şev ve duvar yerleşimleri yapılmalıdır. Yeraltı suyu ve yağmur suyunun denetimi drenaj sistemi ile sağlanarak zeminin kararlılığı korunmalıdır. Depo sahasının yapısına göre balastlı ya da balastsız üstyapı tipi seçilerek tasarım şekillenir. Yapılar içerisinde bulunan hatlar daha çok balastsız üstyapı tipinde yapılırken, doğal zemin üzerinde bulunan hatlar çoğunlukla balastlı üstyapı tipinde yapılmaktadır. Hat geometrisi, depo sahası yerleşimini en çok etkileyen etken olduğu için, yatay ve düşey geometri tasarımları dikkatle yapılmalıdır. Metro araçlarının özelliklerine uygun ve hizmet kapasitesini düşürmeyen özellikte, yatay ve düşey geometri elemanları ile makaslar belirlenip tasarımlar yapılmalıdır. Tasarımı etkileyen etkenlerin yanı sıra, tasarıma ilişkin belirlenmiş olan ölçütler de göz önünde bulundurulmalıdır. Metro depo sahası hatları; hat tasarım ölçütlerine bakılarak, hat geometrisinde istenen şartları sağlamalıdır. Atölye yapıları tasarım ölçütleri de dikkate alınarak, atölye gereksinimleri ve alanları belirlenir ve atölye tasarımı tamamlanabilir. Metro hatları ve depo sahaları yerleşim yerlerinde bulunduğu için, çevreye verdiği rahatsızlıkları belirli seviyelerin altında tutmak amacıyla, çevresel gürültü ve çevresel titreşim ölçütleri dikkate alınmalıdır. Metro depo sahası tasarımını etkileyen bu etkenler ve ölçütler ışığında, Üsküdar-Ümraniye-Çekmeköy metro hattı depo sahası için ihale dokümanında hazırlanmış olan uygulamaya esas kesin proje tasarımı incelenmiş, eksiklikleri belirlenmiş ve yerine yeni bir ön proje tasarımı hazırlanmıştır. Üsküdar-Ümraniye-Çekmeköy metro hattı depo sahası için topoğrafyası engebeli bir arazi ayrılmıştır. Hat, İstanbul’un yoğun yerleşim bölgesinde planlandığı için, depo sahasının yapılabileceği uygun bir arazi bulmak zordur. Kamulaştırma bedellerinin yüksek olması ve kamulaştırmalara karşı açılan davaların uzun yıllar boyunca sürmesi de göz önünde bulundurulduğunda, elde olan arazinin kullanılmasına karar verilmiştir. Daha etkili ve verimli bir şekilde arazi kullanımı sağlamak amacıyla, 110 m ve 120 m olmak üzere iki ayrı kotta, kademeli bir şekilde depo sahası tasarımları yapılmıştır. Tam otomatik sürücüsüz sistem ile işletim için, gerekli kumanda ve kontrol merkezi, sinyal sistemi ve hat tasarımı ile depo sahası tasarımları düzenlenmiştir. Atölye bakım hatları ve atölye binası içindeki teknik alanlar, ilgili ölçütler dikkate alınarak yeniden tasarlanmış, ortaya daha büyük ve yüksek kapasiteli bir atölye tesisi çıkmıştır. Araç park hatlarının sayısı 33’ten 68’e çıkarılmıştır. Alınacak araçlar belirlenerek, araç özellikleri tasarımlarda göz önüne alınmıştır. Depo sahasını kullanan metro hatlarının girişleri birbirinden ayrılarak, işletme açısından ortaya çıkabilecek karışıklıkların ve oluşabilecek araç trafiğinin önüne geçilmiştir. İtfaiye araçlarının ve büyük tırların kullanımına uygun, depo sahası içerisindeki bütün tesislerin ulaşımını sağlayan karayolu bağlantıları yapılmıştır. Tam otomatik sürücüsüz sistemde güvenlik sorunları çıkaracak hemzemin geçişler kaldırılmış, yalnızca araçların elle kumanda edildiği atölye girişlerinde hemzemin geçişler konulmuştur. Gürültü ve titreşim azaltıcı çözümler getirilmiş, çevreci bir drenaj ve atık kaldırma sistemleri tasarlanmıştır. Metro hatları ile depo sahası arasındaki ulaşım güvenilirliğini sağlayacak, farklı güzergahlarla ulaşım sağlayabilen bağlantı yolları tasarlanmıştır. 800 m uzunluktaki test hattı bağlantı yolu üzerine yerleştirilmiştir. Tesisin güvenliği için yüksek duvar ve tel çitler konulup, kameralarla denetim sağlayabilecek tasarımlar sunulmuş, can güvenliği için hatlara insan erişimini engelleyecek tel çitler yerleştirilmiştir. Araçlara cer gücünü sağlayacak trafo merkezi ve rijit katener sistemi hazırlanmış, elektrik kesintisinde hizmete girecek bir kojeneratör sistemi tasarımlara eklenmiştir. UIC 54 (54 E 1) tipi ray ve ön germeli beton travers ile balastlı üstyapı sistemi kurularak depo sahası yerleşimleri yapılmıştır. Atölye binası içindeki bakım hatları için, betona gömülü oluklu ray ile balastsız üstyapı sistemi seçilmiş ve iki katlı park hatları binasının alt katındaki park hatlar için, betona sabit balastsız üstyapı sistemi seçilmiştir. Hat geometrileri tasarlanırken, arazi koşulları nedeniyle düşey geometri ölçütleri aşılmak zorunda kalınmıştır. Çekici araçların bu düşey geometri koşullarına uyumlu olması ve yeterli güce sahip olması durumunda, ortaya çıkabilecek olumsuzlukların önüne geçilebilir. En küçük yatay kurp yarıçapı 80 m, en küçük düşey kurp yarıçapı 2000 m, en büyük eğim %4 ve makas tipi 1/7 R 140 seçilerek tasarımlar yapılmıştır. Metro depo sahası tasarımları yapılırken, işletmenin gereksinimleri, araç özellikleri önceden bilinmeli ve tasarım ona göre şekillenmelidir. Daha verimli olan tam otomatik sürücüsüz sistem tercih edilmelidir. Depo sahasında hız ve konforun düşük olması ve yerleşim bölgesinde uygun arazi yapısı olan bir alanın bulunmasının zor olması göz önünde bulundurularak, hat geometrisi ölçütleri ve standartları konusunda daha esnek olunmalıdır.

Metro depot area is needed to include operating, cleaning, maintenance and repair, overhaul, material requisition and parking areas for vehicles. Designing these facilities, many factors and criteria have to be taken into account. First of all, Istanbul metro lines and their depot areas are mentioned in this thesis study. Then designing factors and criteria for a metro depot area are highlighted. Afterwards, final design project in the contract of Istanbul Uskudar-Umraniye-Cekmekoy metro line is being analyzed and a new conceptual design project for metro depot area is being developed. Finally, by taking into consideration of the results indicated, new suggestions and aspects about metro depot design are being made. Factors for designing metro depot area are; location and site selection, operation, workshop and maintenance services, parking tracks, vehicle features, rood connection, city and environment interaction, access tracks, security, electromechanical systems, infrastructure, superstructure and track geometry parameters. Criterion of track design, criterion of workshop design and criterion of environmental noise and vibration are needed to be taken in consideration as design criterions. Metro depot area is needed to be close to the metro lines which are being connected. The area is needed to be appropriate and big enough for the selected facilities, and smooth terrain are better to establish the facilities. Operation building and facilities are being designed and areas are being selected which are appropriate and sufficient for entire operational scenarios and have control center. Requests of operator firm are being considered in the name of not having trouble during operation. The capacity of workshop and maintenance services is determined regarding to the serving to metro vehicles. Double entry workshop is generally being preferred. However, single entry workshop may be designed according to the field situation. As the main purpose of a metro depot area is serving to metro vehicles, the facilities are designed according to properties of metro vehicles. Settlement of the tracks, workshop and the other facilities are being done accordingly static and dynamic gauge, length of the vehicles and properties of appropriate track geometry. Proper highway connections are needed for the transportation of workers, materials and metro vehicles. Rood design is necessary in the state of emergency for the emergency response vehicles using the roods. In concordance with city, controlling over the noise and vibration are required by designing of depot area. Environmental impacts are being reduced by compatibility with city and environmental, keeping under control environmental noise and vibration, storage and disposal of wastes, treatment of waste water and ecological drainage systems. Access tracks provides security between metro line and depot area and in case of trouble it should be maintained the transportation with different routes. For the security of depot area, entry and exit points are needed to be controlled and protected with hedges and walls against intrusions. Access of people to track corridors should be limited for security of life. Traction transformer and appropriate catenary systems are being designed to meet the traction force of vehicles. Necessary facilities for signage systems are being established on behalf of controlling the vehicles and traffic stream. Required side slopes and retaining walls settlements are being done by selecting the proper material for infrastructure. Infrastructure design is needed to be developed by providing drainage system to control groundwater and storm water. The stability of soil could be provided by means of drainage system. Design is being shaped by selecting ballasted track or ballastless track according to the configuration of depot area. Generally, tracks in building are ballastless and tracks on soil are ballasted. Track geometry is the main factor on settlement of a depot area. Tracks are being settled by horizontal and vertical geometry design and selection of turnout geometry which are appropriate for depot area. These geometries are needed to be appropriate for vehicles and nonrestrictive for the capacity of metro depot area. Beside of these factors, regarding design criterions is required to be considered. Preferred conditions on track geometry are being provided thereby the design criterions of track geometry. Design of workshop can be completed by determining the necessity and area of workshop considering workshop design criterions. To keep under control environmental disturbance, environmental noise and environmental vibration criterions are needed to be considered. The final design project in the contract of Istanbul Uskudar-Umraniye-Cekmekoy metro line is being analyzed and its deficiencies are being disclosed in the light of design criterions and factors of metro depot. In place of this design, new conceptual design project is being developed. Metro depot area in the project has rugged terrain. Since the metro line is projected on intensive residential area of Istanbul, it is hard to find an appropriate land for depot area. Because of high level of expropriated price and long cases against expropriation, it is decided to continue to work on same land. Therefore, with the purpose of efficiently usage of the land, depot area is being designed by arranging land on two different elevations which are 110m and 120m. Design of the depot area is arranged by control center, signal system and track design for unmanned full-automatic operation system. Capacity of workshop building and depot area is expanded by integrating two workshop building in different areas. Daily cleaning services are taken to parking tracks. Number of vehicle parking lines is increased from 33 to 68. New design project is shaped regarding to properties of metro vehicles. Depot area entrance of subway lines is being separated for the purpose of preventing disorder and potential vehicle traffic. A new road design is being developed for the usage of fire trucks and trailer trucks. All facilities are connected with road. Level crossings are settled only at the entrances of workshop which vehicles controlled manually to avoid safety problems on unmanned full-automatic operation system. Ecological drainage systems, storage and disposal of wastes and equipment for restriction of environmental noise and vibration are designed. Access roads are planned to provide reliability of transportation between metro lines and depot area and also different routes. 800-meter-long test track is settled on access road. Razor wire and wire fences on high walls and monitor system are designed for the security of properties. For the security of life, wire fences are put to prevent access to tracks. A transformer and rigid catenary system are prepared to provide traction force for vehicles. A cogenerator system is added to design to put into service in case of power cut. Ballasted track system with UIC 54 (54 E 1) type rail and pre-stressed concrete sleeper are selected and settled. In the workshop building, superstructure should be as flange rail embedded in concrete. On ground floor of parking building, superstructure should be as ballastless track. Because of condition of terrain, it is contravened vertical geometry criterions. To prevent problems of this situation, shunting vehicle is needed to be proper to the vertical geometry. The minimum radius of horizontal curve as 80 m, the minimum radius of vertical curve as 2000 m, the maximum slope as 4% and turnout type as 1/7 R 140 are selected then design is prepared. By designing a metro depot area, requirements of the operating firm, properties of vehicles should be known before designing period and design is needed to be shaped accordingly. Unmanned full-automatic operation system should be selected for further efficiency. The speed and comfort in the depot area is restricted, and it is hard to find an appropriate land in urban area. Therefore, flexibility is needed on criterions and standards of track geometry.

Yüksek Lisans

M.Sc.

PERFORMANCE ANALYSIS AND PRICING IN BROADBAND NETWORKS

Scipedia content — Tue, 26 Jan 2021 17:16:46 +0100

'n Ondersoek na draaiveldmasjiene met elektroniese kommutators vir aandrywing van elektriese voertuie

Scipedia content — Tue, 26 Jan 2021 17:15:01 +0100

M.Sc. (Electrical & Electronic Engineering) The behaviour of alternating current machines being fed from an electronic commutator is investigated. The performance of compound power switches for use in electric vehicle drives are examined. A detailed study on switching losses and base current characteristics based upon experimental measurements was carried out. With further reference to power switches the merit, development and functioning of an electronic commutator is discussed. Because of the close association between this study and electric vehicle drives, a comparative study of the performance of different rotor types within the same machine was executed. Attention is paid to torque and efficiency characteristics in particular. The influence of voltage and current harmonics was established by comparative testing of the machine with sinusoidal and electronic commutator excitation. The study shows that the highest specific power was attained with the alternating current machine with a wound rotor (synchronous machine) while there seems to be merit in the use of permanent magnet rotors for electric drives as well. On the average the use of electronic commutator excitation resulted in an efficiency decrease of approximately 15% for the a.c. machine with different rotor types. Efficiency and torque for an induction machine with solid rotor were disappointing so that there seems to be little application for solid steel rotors. A simple model for the synchronous machine with wound rotor was developed to explain the dependence of torque and efficiency upon speed of rotation and commutation angle. To conclude, guidelines are given for future studies on electric vehicle drives and machine types as primary drive.

Solar PV in multi-family houses with battery storage

Scipedia content — Tue, 26 Jan 2021 17:10:20 +0100

This thesis investigates the economic viability of a grid connected PV system integrated with battery storage in a multifamily home in Sweden. In addition, a fleet of electric cars is added to the system and its economic feasibility is analyzed. The analysis is further classified based on the roof area available for PV installation, wherein system 1 considers nearly the entire roof area of 908 m2 and system 2 is assumed to have less than half the roof area of 360 m2 for PV installation. To help with the assessment, five scenarios are created; where scenario one represents a baseline Swedish cooperative without PV, scenario two includes a PV system; scenario three incorporates battery storage; four considers an electric vehicle fleet embedded into the system and scenario five has a fleet of gasoline cars. These scenarios are applied to the two systems and their results compared. To address the question of this thesis both scenarios 2 and 3 are simulated in System Advisor Model (SAM) and scenario 4 is modeled in Matlab. The outputs are exported to Excel in order to obtain the Net Present Value (NPV), which is the economic indicator for this assessment. In none of the tested scenarios the NPVs’ are positive and the best result is observed in a PV system installed with battery storage in a roof area of 360 m2, which has a NPV of -82,000 SEK. A sensitivity analysis is done to assess the changes in NPV by varying the input parameters. It is concluded that battery storage is not yet economically viable in a Swedish multifamily house.

Battery repurposing of plug-in electric vehicles: a framework for the integration of renewable energy and electrified transportation

Scipedia content — Tue, 26 Jan 2021 17:10:04 +0100

comprehensive framework is presented for the integration of electrified transportation and renewable energy through repurposing batteries of plug-in electric vehicles towards a sustainable energy future. The framework considers future market penetration scenarios of plug-in electric vehicles, availability of batteries at their vehicular end of life, and the storage capacity required to generate base-load wind power in the region of study. The objective is to develop a model that can be used as a policy tool to investigate how different scenarios and pertinent parameters can effectively meet the challenges of sustainability in the energy and transportation sectors when the ultimate goal is to simultaneously displace fossil fuels with new generation of low-cost intermittent renewable energy. A sample case study is performed for Canada to investigate and verify the performance of the model. The analysis shows that the proposed approach can further improve the energy sustainability performance of Canada in 2050 by 1.65–4.11%, depending on the confidence level and in addition to electrification of transportation. In the framework, a statistical algorithm is developed to calculate the capacity of an energy storage system required for delivering base-load electricity for a wind farm in the future electric grids. The algorithm contributes towards the goal of utilizing low- cost intermittent wind energy to base-load power generation in the future electric grids. The introduced algorithm presents three methods to perform the sizing calculations each representing a scenario associated with the stages of the wind energy industry. The results of the studied case are applied to estimate the cost of wind energy to produce rated power at different confidence levels, which show cost-effectiveness and less intermittency on the power systems allowing for larger penetrations of renewables. Advanced statistical methods are used to more accurately characterize the operational wind power output versus manufacturer’s power curve. This is essential for effective integration of wind power into the power systems. Four parametric and nonparametric models are applied to estimate the power curve of wind turbines based on the available operational wind power data. The results of this study suggest that the penalized spline regression method presents a better performance over the other analyzed methods. Finally, an experimental testing is performed in laboratory to show the proof of concept of the capacity degradation of used batteries of plug-in electric vehicles in stationary applications using a 25 kWh repurposed energy storage system obtained from a taxi fleet in their “as-is” condition. The proposed comprehensive framework herein presents an approach leading to a sustainable transportation system by providing low-cost renewable energy, and can be used as a gold standard to compare other policies like hydrogen energy technologies. October 2015

Predictability in Strategic Air Traffic Flow Management

Scipedia content — Tue, 26 Jan 2021 17:08:41 +0100

This dissertation investigates predictability in strategic air traffic management with a focus on ground delay programs (GDPs). Through a survey of flight operators, we confirm the proposition that flight operators care about predictability. We then develop models that incorporate predictability into GDP cost optimization after failing in finding an existing model that can serve this purpose. This is accomplished by modifying traditional GDP delay cost functions so that they incorporate predictability, and determining the sensitivities of the optimal planned capacity recovery time and associated cost to the unpredictability premiums included in the cost functions. To do this, we develop two stochastic GDP models: a GDP no-revision, or static, model; and a GDP revision, or dynamic, model considering one GDP revision. GDP scope, which matters only in the revision model, is also considered. The optimization results from the case study show that the cost of unpredictability clearly matters, particularly in the more realistic case where GDP revision is allowed. Of the two unpredictability cost parameters, the one for unplanned delay has a stronger impact than the one for planned un-incurred delay. The insights from this analysis might eventually be used to develop a decision support tool that air traffic managers could use in determining what the planned end time should be for a GDP in a manner that reflects the importance of predictability to flight operators.

Strategic planning of aircraft trajectories

Scipedia content — Tue, 26 Jan 2021 17:05:41 +0100

To sustain the continuously increasing air traffic demand, the future air traffic management system will rely on a so-called Trajectory Based Operations (TBO) concept that will increase air traffic capacity by reducing the controller's workload. This will be achieved by transferring tactical conflict detection and resolution tasks to the strategic planning phase. In this future air traffic management paradigm context, this thesis presents a methodology to address such strategic trajectory planning at nation-wide and continent scale. The proposed methodology aims at minimizing the global interaction between aircraft trajectories by allocating alternative departure times, alternative horizontal flight paths, and alternative flight levels to the trajectories involved in the interaction. To improve robustness of the strategic trajectory planning, uncertainty of aircraft position and aircraft arrival time to any given position on the trajectory are considered. This thesis proposes a mathematical formulation of this strategic trajectory planning problem leading to a discrete-optimization and a mixed-integer optimization problem whose objective function relies on the new concept of interaction between trajectories. A computationally efficient algorithm to compute interaction between trajectories for large-scale applications is introduced and implemented. Resolution methods based on metaheuristic and hybrid-metaheuristic algorithms have been developed to solve the above large-scale optimization problems. Finally, the overall methodology is implemented and tested with air traffic data taking into account uncertainty over the French and the European airspaces, involving more than 30,000 trajectories. Conflict-free and robust 4D trajectory planning are produced within computational time acceptable for the operation context, which shows the viability of the approach.; Afin de pouvoir satisfaire la demande sans cesse croissante du trafic aérien, le futur système de gestion du trafic aérien utilisera le concept d'opérations basées sur les trajectoires (Trajectory Based Operations), qui augmentera la capacité du trafic aérien, en réduisant la charge de travail du contrôleur. Pour ce faire, les tâches de détection et de résolution de conflits seront transférées depuis la phase tactique vers la phase stratégique de la planification. Dans le cadre de ce nouveau paradigme pour le système de gestion du trafic aérien, nous introduisons dans cette thèse une méthodologie qui permet d'aborder ce problème de planification stratégique de trajectoires d'avion à l'échelle d'un pays ou d'un continent. Le but de la méthodologie proposée est de minimiser l'interaction globale entre les trajectoires d'avion, en affectant de nouveaux créneaux de décollage, de nouvelles routes et de nouveaux niveaux de vols aux trajectoires impliquées dans l'interaction. De plus, afin d'améliorer la robustesse du plan stratégique de vols obtenu, nous prenons en compte l'incertitude de la position de l'avion et de son heure d'arrivée à un point donné de la trajectoire de l'avion. Nous proposons une formulation mathématique de ce problème de planification stratégique conduisant à un problème d'optimisation discrète et un problème d'optimisation en variables mixtes, dont la fonction objectif est basée sur le nouveau concept d'interaction. Un algorithme efficace en termes de temps de calcul pour évaluer l'interaction entre des trajectoires d'avion pour des applications de grande taille est introduit et mis en œuvre. Des méthodes de résolution basées sur des algorithmes de type métaheuristique et métaheuristique hybride ont été développées pour résoudre ces problèmes d'optimisation de grande taille. Enfin, la méthodologie globale de planification stratégique de trajectoires d'avion est mise en œuvre et testée sur des données de trafic, prenant en compte des incertitudes, pour l'espace aérien français et l'espace aérien européen, impliquant plus de 30000 vols. Des plans de vols 4D sans conflits et robustes ont pu être produits avec des temps de calcul acceptables dans un contexte opérationnel, ce qui démontre la viabilité de l'approche proposée.

Conjoint design of railway lines and frequency setting under semi-congested scenarios

Scipedia content — Tue, 26 Jan 2021 16:49:57 +0100

This thesis develops mathematical programming models which integrate network design (ND) and line frequency setting (LFS) phases. These appear in transport planning studies that extend an existing urban public transportation system (UPTS) and are suitable for underground and rapid transit systems. The ND phase extends the working UPTS, taking as inputs the locations of candidate stretches and stations on the new lines, as well as construction costs which cannot exceed the available infrastructure budget. Regarding the LFS phase, frequencies and vehicles are assigned to functioning and newly built lines, providing that they do not exceed resource capacities and the time horizon. The developed models take into account the type of service patterns that may operate on the lines of the transport system. They include local services, where vehicles halt at every node in the line, and express services, in which vehicles halt at only a subset of nodes in the line. A passenger assignment model allows solving, simultaneously, the ND and LFS phases under a system optimum point of view. The combined model has two variants: one which deals with inelastic demand and another which faces elasticities in demand. The latter originates from changes in the modal choice proportions of travelers and may result from modifications in the public transport system. The former does not take into account competition among several modes of transportation and it is formulated as a mixed-integer linear programming problem. In contrast, the latter allows passengers to travel via two modes of transportation: public transport and private car. It is formulated as a mixed-integer linear bi-level programming problem (MILBP) with discrete variables only in the upper level. In both models, a complementary network is used to model transfers among lines and to reach the passenger¿s origin and/or destination nodes when the constructed UPTS does not cover them. The model with inelastic demand is initially solved by means of the commercial solver CPLEX under three different mathematical formulations for the ND phase. The first two are exact approaches based on extensions of Traveling Salesman Problem formulations for dynamic and static treatment of the line¿s subtours, whereas the last one is an approximation inspired by constrained k-shortest path algorithms. In order to deal with large-sized networks, a quasi-exact solution framework is employed. It consists of three solving blocks: the corridor generation algorithm (CGA), the line splitting algorithm (LSA), and a specialized Benders decomposition (SBD). The LSA and CGA are heuristic techniques that allow skipping some of the non-polynomial properties. They are related to the number of lines under construction and the number of feasible corridors that can be generated. As for the SBD, it is an exact method that splits the original mathematical programming problem into a series of resolutions, composed of two mathematical problems which are easier to solve. Regarding the elastic demand variant, it is solved under the same framework as the specialized Benders decomposition adaptation for solving MILBP, which results from this variant formulation. The inelastic demand variant is applied to two test cases based on underground network models for the cities of Seville and Santiago de Chile. Origin destination trip matrices and other parameters required by the models have been set to likely values using maps and published studies. The purpose of these networks is to test the models and algorithms on realistic scenarios, as well as to show their potentialities. Reported results show that the quasi-exact approach is comparable to approximate techniques in terms of performance. Regarding the elastic demand variant, the model is more complex and can be applied only to smaller networks. Finally, some further lines of research for both modeling and algorithmic issues are discussed.

Electric vehicles as energy processing and conversion systems

Scipedia content — Tue, 26 Jan 2021 16:47:07 +0100

D.Ing. (Electrical & Electronic Engineering Science) In the light of a history of more than a century, and reviving interest over the last three decades, battery powered electric vehicles are seen as one of the contributing technologies to alleviate transport problems in the future. This thesis is concerned with the use of energy in road transport. In particular, some selected aspects of the application of battery powered road vehicles are addressed. The thesis gives a brief background history and reviews the forces and factors which presently play a role in the developments and future application of battery electric vehicles. The main contribution, however, lies in the field of technical clarification of some aspects of electric vehicle theoretical analysis, which have not been addressed before. The first of these technical subjects is the analysis of energy consumption of vehicles when operating under non-steady driving conditions. The analysis results in simple but relevant expressions for the energy consumption of any moving vehicle during start-stop driving, as well as driving over a hilly route. The potential benefit of kinetic energy recovery can be quantitatively determined. The theory is then applied to battery electric vehicles and the results are compared to actual recorded energy consumption figures. The second technical investigation concerns the optimisation of electric vehicle drive systems with respect to mass. It is shown that optimized drive systems should be designed to suit both the energy density characteristics of the batteries used, as well as the particular characteristics of the drive cycle to which the vehicles will be applied.

Managing fatigue in a regional aircraft operator : fatigue and workload on multi-segment operations

Scipedia content — Tue, 26 Jan 2021 16:43:01 +0100

Introduction: With the constant increase in air travel every year and the downfalls of the World’s economy, airline managers face the need to optimize resources with the goal of reaching profit and reliability targets. This leads to higher utilization rates in commercial aircrews, with more hours of work and the consequence of less sleep and off time. As such, pilots and cabin crew face an increasing number of sleep disturbances, with the consequent alertness impairments and reduced performance. The concept of fatigue resumes these issues and has recently been addressed by several studies and documents, which prove its hazards and identifies them as risks to a flight’s safety. The main goal of this study is the methodic identification of fatigue in a regional aircraft operator that, although not suffering from night circadian disruption has a major rostering structure of multi-flight operations with flights in the early hours of the day. Methodology: The universe and the sample size of this study are equal and correspond to 52 airline pilots, 27 Captains and 25 First Officers, all males and an average age of 39.2 years old. The methodology used in this research consists of two interconnected principles: objective fatigue measurement, using bio-mathematical modeling through the SAFE model and subjective fatigue measurement through a 3 week daily survey applied to real operations, allowing the measurement of individual fatigue in the beginning of work and at top of descend on the last flight of the day. The survey was complemented by an adapted version of NASA’s TLX workload measurement scale, allowing a more complete analysis of an additional fatigue cause that has impact in multi-segment operations. A questionnaire was also distributed in order to identify any variability factors that could influence the measurements and limit pilot’s capabilities and performance.Results: Results were determined by setting a methodic approach to schedule analysis, with 365 days of planned pilot rosters processed. Areas of high risk were identified, in particular on the early hours of the morning and the evening and on days with more than 4 sectors. With the surveys and when comparing both measurements, SAFE model predictions stay short of 5 in the Samn-Perelli Scale (Moderately tired. Let down.) whilst pilot reported fatigue values represent a 6 on the same scale (Extremely tired. Very difficult to concentrate.). A high relation was also found between the increase of fatigue, the number of sectors and time of day, revealing that workload might be caused by multi-segment operations and a hazard to what can be considered an acceptable level of safety to risk management in flight operations. Conclusion: A new approach to workload in the fatigue and safety settings should be considered, and further research should strive to look at the impact of workload in multi-segment operations. This should all lead to new hazard identification and risk mitigation practices to be in place, joining flight safety and rostering departments in better and more robust schedules, with of course increased safety levels and better overhaul performance.

Orientação : Anabela Simõe

Aprovisionamento inter-domínio de caminhos de luz em redes com multiplexação por comprimento de onda

Scipedia content — Tue, 26 Jan 2021 16:29:15 +0100

Orientador: Nelson Luis Saldanha da Fonseca Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Computação Made available in DSpace on 2018-08-28T20:53:25Z (GMT). No. of bitstreams: 1 Pontes_AlissonSoaresLimeira_M.pdf: 2584435 bytes, checksum: cbcb6945d130888c12f72f8123e74467 (MD5) Previous issue date: 2015 Resumo: Apesar dos avanços em aprovisionamento de caminhos ópticos intra-domínio em redes Wavelength Division Multiplexing (WDM), esquemas eficientes para cálculo de rota e divulgação de recursos ópticos em redes multidomínio em malha ainda não foram plenamente estabelecidos. Por estarem sujeitos a restrições de escalabilidade e restrições de divulgação de estado da rede, os domínios ópticos precisam de esquemas simples e eficientes. A maioria das soluções apresentadas na literatura não suportam Engenharia de Tráfego e são baseadas em técnicas de inundação periódica de mensagens de controle. Esta dissertação apresenta três propostas de aprovisionamento de caminhos ópticos em redes WDM multi-domínio baseadas na arquitetura Path Computation Element (PCE). As propostas são formadas por um esquema de disseminação de informações sobre o estado da rede combinado a um esquema de cálculo de cadeia de domínios e cálculo de rota fim-a-fim. Considera-se que os comutadores da rede óptica não realizam conversão de comprimento de onda. Desta forma, o cálculo de rota está sujeito ao problema da restrição de continuidade de comprimento de onda. As propostas também apresentam políticas de atribuição de comprimento de onda que provêm balanceamento na distribuição dos caminhos ópticos. Os ganhos obtidos na utilização das propostas apresentadas são avaliados através de simulações usando o simulador de redes WDMSim. A efetividade da primeira proposta foi comparada com a de uma implementação do protocolo OBGP utilizando-se o simulador WDMSim. A probabilidade de bloqueio gerada pelo OBGP foi até 13 pontos percentuais maior que a probabilidade de bloqueio da proposta 1, enquanto que a sobrecarga de controle gerada pelo OBGP foi de até 5 ordens de magnitude maior que a gerada pela proposta 1. A efetividade da segunda solução foi comparada com a da primeira solução utilizando-se o WDMSim. Mostrou-se que a probabilidade de bloqueio da proposta 1 foi até 10 vezes maior que a probabilidade de bloqueio da proposta 2. A sobrecarga gerada pela proposta 2 foi muito baixa para todos os valores de carga considerados, enquanto que para a solução 1 a sobrecarga cresce com o aumento da carga. O desempenho da terceira abordagem é avaliado considerando diferentes parâmetros. As simulações realizadas confirmam que o grande crescimento da sobrecarga de sinalização ao se atingir vários PCEs no processo de atualização vai de encontro ao potencial de diminuição da probabilidade de bloqueio devido a instabilidade gerada nas TEDs. Sendo assim, das três soluções apresentadas, a segunda foi a que se mostrou mais eficiente em termos de probabilidade de bloqueio Abstract: Despite advances in provisioning intra-domain lightpaths in Wavelength Division Multiplexing (WDM) networks, efficient schemes for path computation and advertisement of optical resources in multi-domain mesh networks have not yet been fully established. Because they are subject to scalability constraints, optical domains need simple and efficient schemes. Most of the solutions presented in the literature do not support traffic engineering and are based on periodic flooding of control messages. This work presents three proposals for provisioning lightpaths in multi-domain WDM networks based on the Path Computation Element (PCE) architecture. Proposals are formed by a schema for advertising information about network link state combined with domain chain computation and end-to-end route computation schemes. It is considered that the network optical switches do not perform wavelength conversion. Thus, the route computation is subject to the problem of wavelength continuity constraints. The proposals also present wavelength assignment policies that provide balance in the distribution of optical paths. The gains made in the use of the proposals submitted are evaluated through simulations using the WDMSim networks simulator. The effectiveness of the first proposal was compared to an implementation of the OBGP protocol using the WDMSim simulator. The blocking probability generated by OBGP was up to 13 percentage points higher than the blocking probability of the proposal 1, while the control overhead generated by OBGP was up to 5 orders of magnitude greater than that generated by the first proposal. The effectiveness of the second solution was compared to the first solution using the WDMSim. It was shown that the blocking probability generated by the first proposal was up to 10 times greater than the blocking probability of the second proposal. The control overhead generated by the proposal 2 was very low for all load values considered, while for the solution 1 overloading grows with load increasing. The performance of the third approach is evaluated considering different parameters. The simulations performed confirm that the growth of signaling overhead to achieve several PCEs in the updating process goes against the pontencial decrease of blocking due to instability caused in TEDs. Thus, considering the three solutions presented, the second was the more efficient in terms of blocking probability Mestrado Ciência da Computação Mestre em Ciência da Computação 2010/03020-4 FAPESP CAPES

Solução unificada para tração e carregamento das baterias em veículos elétricos

Scipedia content — Tue, 26 Jan 2021 16:27:29 +0100

Dissertação de mestrado integrado em Engenharia Eletrónica Industrial e Computadores Nowadays, Electric Vehicles are emerging as the most sustainable alternative to support the expected rise in the number of vehicles in circulation around the world, and to reduce the impact of the transportation sector on the environment. However, this is a technology that still has some limitations that restrict its mainstream adoption. Typically, an Electric Vehicle has a motor drive system and an on-board battery charger that allows charging its battery pack almost anywhere, as long as there is an electrical outlet available. However, this is usually a low-power charger in order to optimize the space and weight on-board the vehicle. As a result, this type of charging typically takes a couple of hours. The purpose of this MSc. Thesis was the development of a unified power electronics converter, capable of performing the roles of drive the electrical machine of an Electric Vehicle and also charging its battery pack, so as to optimize the space and weight of the power electronics components on-board the vehicle while also providing a faster charging operation. The first part of this MSc. Thesis consisted in the study of the state of art of the unified hardware solutions proposed, based on the use of the power electronics components of the motor drive system during the battery charging operation, since both operation modes cannot be performed simultaneously, except for regenerative breaking. Also the respective control algorithms that allow perform each operation mode, according with the solution proposed, were studied. The second part consisted in simulating the proposed unified solution and implementing a proof-of-concept prototype. In the proposed solution the battery charger is based on the use of a three-phase Voltage Source Inverter and the windings of a Brushless DC machine. With respect to the control algorithms, for the motor drive mode the Field-Oriented Control was chosen, while for the battery charging mode two control algorithms were chosen (one for single-phase charging and the other for three-phase charging), based on the Model Predictive Control. The obtained results validate the proposed solution. However, in the case of the electrical machine used in this MSc. Thesis, the values of the inductances of its windings compromise its use as an input filter. Atualmente os Veículos Elétricos surgem como a alternativa mais sustentável perante o aumento expectável do número de veículos em circulação no mundo e por forma a reduzir o impacto ambiental do sector do transporte. Contudo, esta é ainda uma tecnologia com algumas limitações, que ainda não permitiram a sua aquisição em maior escala. Tipicamente um Veículo Elétrico possui um sistema de tração e um sistema de carregamento, que permite carregar as suas baterias em praticamente qualquer local, desde que haja disponível uma tomada ligada à rede elétrica. No entanto, este sistema de carregamento tem normalmente uma potência instalada baixa, por forma a otimizar o espaço e peso ocupados no interior do veículo. Como resultado, este tipo de carregamento demora tipicamente algumas horas. Esta Dissertação de Mestrado teve como objetivo o desenvolvimento de um conversor unificado, capaz de controlar a máquina elétrica usada para a tração de um Veículo Elétrico e de carregar as suas baterias, permitindo otimizar ainda mais o espaço e peso ocupados pelos componentes de eletrónica de potência instalados no veículo e possibilitar ainda carregamentos mais rápidos. A primeira parte desta Dissertação consistiu num estudo do estado da arte de sistemas de hardware unificados, baseados na utilização dos componentes de eletrónica de potência do sistema de tração durante o modo de carregamento das baterias, tendo em conta que as duas operações não podem ser realizadas em simultâneo, exceto para travagem regenerativa. Também foram estudados os algoritmos de controlo que permitem executar cada uma das operações, de acordo com a topologia proposta. A segunda parte consistiu na simulação da solução proposta e na implementação de um protótipo para demonstração da funcionalidade. Nesta solução proposta, o sistema de carregamento baseia-se na utilização de um inversor trifásico do tipo Voltage Source Inverter e dos enrolamentos de uma máquina elétrica do tipo Brushless DC. Em relação aos algoritmos de controlo, para o modo de tração foi selecionado o Controlo por Orientação de Campo (Field-Oriented Control), enquanto que para o modo de carregamento foram selecionados dois algoritmos (um para carregamento monofásico e outro para trifásico), baseados no Controlo Preditivo (Model Predictive Control). Os resultados obtidos permitiram validar a solução proposta. Contudo, os baixos valores de indutância da máquina elétrica usada comprometem o seu uso como filtro de entrada.

Inefficiencies of Quasi-Market Solutions from an Institutional Perspective: A qualitative case study comparison of local public transportation in six cities in Germany and Finland

Scipedia content — Tue, 26 Jan 2021 16:26:07 +0100

Näennäismarkkinoiden tehottomuus Tutkimuksessa vertaillaan julkisen joukkoliikenteen järjestämistapoja: julkista monopolia, yksityistä monopolia ja kilpailutettua mallia. Vertaillut tapaustutkimukset ovat Suomesta ja Saksasta. Tutkimus tarkastelee julkisen liikenteen toimijoiden ja instituutioiden tehottomuutta uuden institutionaalisen taloustieteen näkökulmasta. Instituutioiden tehottomuutta tarkastellaan transaktiokustannusteorian avulla ja toimijoiden toimintaa rajoittaneen rationaalisuuden näkökulmasta. Tutkimustulosten mukaan kaikkiin järjestämistapoihin liittyy erityistä tehottomuutta. Paikallinen, kansallinen ja eurooppalainen sääntely vaikuttaa järjestämistapojen tehottomuuteen. This study compares three different ways of organising local public transportation. Using the explanatory tools of New Institutional Economics, it reveals which types of inefficiencies occur in actors and institutions involved in organising transportation. Public monopolies, private monopolies and competitive tendering models are investigated and compared in case studies from Finland and Germany. Transaction Costs Economics show the potential inefficiencies of the organisational system, while bounded rationality is used for studying the actor groups. Results show how each organisational setting is prone to different inefficiencies and how they are linked to the local, national and European institutional and regulatory frameworks.

On the ECO2 multifunctional design paradigm and tools for acoustic tailoring

Scipedia content — Tue, 26 Jan 2021 16:22:05 +0100

Nowadays vehicle design paradigm influences not only the effectiveness of the different means of transport, but also the environment and economy in a critical way. The assessment of the consequences that design choices have on society at large are necessary to understand the limits of the methods and techniques currently employed. One of the mechanisms set in motion is the planned obsolescence of products and services. This has affected vehicle design paradigm in such a way that the variety in the market has shadowed the primary function of vehicle systems: the transport of persons and goods. Amongst the consequences of the expansion of such market is the exponential rise on combustion emissions to the atmosphere, which has become a great hindrance for humans health and survival of ecosystems. The development of evaluation tools for such consequences and their piloting mechanisms is needed so as to implement an ECO2 (Ecological and Economical) vehicle design paradigm. Moreover, the multifunctional design paradigm that drives aeronautical and vehicle engineering is an ever-growing demand of smart materials and structures, able to fulfil multiple requirements in an effective way. The understanding of certain phenomena intrinsic to the introduction of novel materials has found certain limits due to the complexity of the models needed. This work presents as a first step an assessment of the causes and consequences of the vehicle exponential market growth based on the analysis of the planned obsolescence within. Furthermore, a method for the acoustic response analysis of multilayered structures including anisotropic poroelastic materials is introduced. The methodology consists in a plane wave approach as a base for introducing the complex mechanic and acoustic equations governing anisotropic homogeneous media, e.g. open-celled foams, into an alternative mathematical tool manipulating physical wave amplitudes propagation within the studied media. In addition, this method is coupled to a power partitioning and energetic assessment tool so as to understand the phenomena present in complex multilayered designs. "p"QC 20150323

Run time evaluation of autonomic network functions trustworthiness

Scipedia content — Tue, 26 Jan 2021 16:21:42 +0100

utonomic networking and self-management are promising concepts for operating large-scale complex networks. Stability, robustness, and security issues arising from future self-organizing networks (SONs) must be under stood today, in order to be incorporated into their design, standardization,and certi cation. The success is gaining ground in addressing the per- ceived concerns of complexity and total cost of ownership of Information Technology (IT) systems. But we are now faced with a challenge springing from this very success. This challenge is trustworthiness and there are limited research results published in this direction. This, if not addressed will de nitely undermine the success of Autonomic Computing (AC). How do we validate a system to show that it is capable of achieving a desired result under expected range of contexts and environmental conditions and beyond? We address the issue of operator trust in Long Term Evolution (LTE) SON through the design and the implementation of veri cation and trust evaluation mechanism which is mandatory in order to avoid reluctance from them to delegate important management tasks to some autonomic entities. This work introduces an online trust assessment framework for autonomic functions and proposes the relevant evaluation mechanisms. This approach addresses trust in terms of reliability and performance of the autonomic entities while it aims to be fully compliant with the Uni ed Management Framework (UMF [12]). It attributes and continuously updates a trust index that characterizes the behaviour of an entity according to its experiences, thus providing useful information to the operator. We present a study ex- ample, related to a SON load balancing autonomic function, to illustrate the methodology of our approach and provide implementation details. Besides, we demonstrate the feasibility and value of the proposed trust assessment framework through a set of numerical evaluations.

Hidden Transcripts on Public Transportation: A Meta-Methodological Exploration of Visual Ethnography in Qualitative Transportation Research

Scipedia content — Tue, 26 Jan 2021 16:18:05 +0100

Better understanding of urban travelers is necessary, as sustainable development is becoming an integral part of transportation policy and practice. A volume of research shows people’s expressed willingness to adopt more sustainable urban travel behaviours, but a general sense of resistance to change is often encountered. Current methods in transportation research are not able to fully grasp on individual motivations such as discontent with public transport. This gap of knowledge in qualitative transportation research calls for the development of new methods. James Scott’s concept of the hidden transcript allows for the assumption that there are expressions of dissatisfaction towards public transportation at grassroots level. In order to access hidden transcripts on public transportation in Stockholm there is a need for a new method, which is developed in this thesis. The proposed visual mixed method draws from principles of visual ethnography, virtual ethnography, nethnography and social media research. The methodology is then tested and assessed as a platform to give voice to hidden transcripts on public transportation. The choice of method for developing the method is meta-methodology. The discussion sheds light on the potential of the framework (1) to grant access to hidden transcripts; (2) to fill a knowledge gap in transportation qualitative research; (3) to assist planners towards sustainable development of urban transportation.

Air traffic controllers' work-pattern during air traffic control tower simulations : A eye-tracking study of air traffic controllers' eye-movements during arrivals

Scipedia content — Tue, 26 Jan 2021 16:17:51 +0100

The aviation industry evolves all the time in every possible sphere with new the technology that is advancing and the increasing amount of traffic on the airports. The air traffic control services has come a long way with automated systems and more advanced technology and the work of the air traffic controller (ATCO) has become more efficient to meet the higher demands for more traffic. But along with highly automated systems and work efficiency there can be a lack of safety instead if there is too much to do for the controller. A new concept in the aviation industry is developing; multiple remote towers, which means that one ATCO can be several miles away from the airports and handle two or more airports at the same time from the same work station. The air traffic controllers has to monitor the aircrafts, direct the traffic, make decisions and make sure that the pilots follows the instructions. At the same time the ATCO need to monitor the systems as well, making sure that everything is working as it is supposed to. To be able to maintain a safe environment for the controllers and the aircrafts, on and surrounding the runways, the controllers need to have situation awareness and the system they are working within need to be resilient to be able to cope with the different kind of situations that might occur. This study has focused on the role of the ATCO in air traffic control towers and by eye-tracking mapped what the controllers are looking at while handling arrivals in two different air traffic control towers. An episode analysis was made on several episodes that took place during different kinds of conditions in the two different air traffic control tower simulators, one single tower simulator and one multiple remote tower simulator. Patterns in the controllers’ way of handling arrivals were identified and the results from the controllers’ eye-movements shows that the ATCOs have a habitual behaviour pattern and that for almost every arrival they will act in the same way. The ATCO in the single tower simulator used the air radar several times during the episodes while in the multiple remote tower simulator the ATCOs almost never looked at the air radar. The radio was used more by the controllers in the multiple remote tower than in the single tower and it is discussed if this is something that can take too much time from an ATCO in a multiple remote tower. The results also highlights the importance of the strip-table, a tool used by the controllers during every step of the arrival process. The conclusions are that the system (controllers and non-human agents) has situation awareness and that the air traffic controllers have a clear frame of the situation. The results from this study can be seen as a guideline and a start for further research in this field and for the development of multiple remote towers. Further research should investigate in the controllers’ ability of reframing in situations of runway incursions and other unexpected events and the usage of the radio in multiple remote towers.

Study of the electric vehicle implementation on the smart grid

Scipedia content — Tue, 26 Jan 2021 16:14:20 +0100

Since some years ago the electric vehicle popularity, and so the pluggable hybrid, notably increased although it's not a brand new development. To understand it, together with the oil prices rise, another factors are to be considered like the CO2 emissions reduction or the fossil fuels dependence. This work is devoted to the study of the electric vehicle integration on the Smart Grid exploring the synergies and the challenges of it. Geographically the study illustrates the Spanish case using as a main data inputs the International Energy Agency forecasts for western Europe together with some highly valuable European Union studies, especially those issued by the JRC. On a first step an electric vehicle market penetration investigation shows that, on year 2030, a 21% of the cars running trough the Spanish roads will be electrically powered. The impact of such a presence of electric vehicles could be assumed, disregarding power grid meshing requirements, by the Spanish electric generation pool and transport infrastructures even if no improvement on them takes place on the next 15 years. The bottleneck will then be found on the low voltage distribution systems and their associated medium voltage lines, that will not be able to hold the electric vehicle deployment forecast unless their capacities are increased or the users car availability is impaired. A solution must be found to this fix this issue that should also explore all the possible synergies with the rest of the electrical system. As a result two countermeasures arise preserving as much as possible the cars availability to their owners. One is to size up all the low voltage and related medium voltage systems to accommodate bigger power flows solving the main problem but doing nothing to integrate the steadily increasing renewal energy that should be consumed when is produced or stored on expensive, environmentally harmful, hydropower pumping stations. The other countermeasure, the main outcome of the next pages, derives from the functionalities of the Smart Grid and is in fact a reviewed version of the, yet popular, Vehicle To Grid (V2G) strategy. Its about to add an inertia battery emulating the inertia tanks in central sanitary water production facilities. Such a kind of proposal is possible because the grid-wide information share and distributed control that lies on the Smart Grid concept. The countermeasure will allow not only a 21% presence of the electric vehicle but even a 100% with almost no cost for the owners, will greatly help the renewables integration as offers a big energy storage capacity on valley hours without compromising the electric vehicles batteries life and also could prevent outages acting as a grid energy supplier in some case

The advancement of electric vehicles - case: Tesla Motors. Disruptive technology requiring systemic innovating

Scipedia content — Tue, 26 Jan 2021 16:11:28 +0100

Electric vehicles have existed for over 100 years as a disruptive innovation. Even though they have always been easier to use, quieter and cleaner, gasoline cars have beaten it in price, range and faster fueling. As gasoline cars have been the technological standard for the past 150 years there has been no motivation by car manufacturers to advance electric vehicles. By producing electric vehicles Tesla Motors has appropriately become the first successful startup car manufacturer in over 100 years. This research studies the systemic innovating of electric vehicles by Tesla Motors. Disruptive innovation is widely researched and often connected to electric vehicles. However systemic innovation has been rarely researched and none has shown that electric vehicles can be seen as one since they require significant adjustments to the business system they are embedded in to succeed as a disruptive innovation. Therefore I suggest that in certain instances a disruptive innovation requires systemic innovating. In the context of electric vehicles systemic innovating can be done on the disruptive technology level of batteries, on the finished product level of the car and on the external level of services such as charging stations. Tesla Motors is doubling the world’s lithium-ion battery production to enable inexpensive electric vehicles. It has produced an electric vehicle platform architecture that has advantages not seen in gasoline cars. It is also creating the standard for charging stations and its battery swapping technology is providing almost instant charging. As Tesla Motors is solving the challenges of high price, low range and slow charging, at the same time it is capitalizing and building on the unique advantages electric vehicles have always had and ultimately proving electric vehicles superiority. This is largely the result of the visionary of Tesla Motor’s CEO Elon Musk who is aiming to transform the world into sustainable energy and transportation through solar panels and batteries.

Searching for causal effects of road traffic safety interventions : applications of the interrupted time series design

Scipedia content — Tue, 26 Jan 2021 16:05:36 +0100

Traffic-related injuries represent a global public health problem, and contribute largely to mortality and years lived with disability worldwide. Over the course of the last decades, improvements to road traffic safety and injury surveillance systems have resulted in a shift in focus from the prevention of motor vehicle accidents to the control of injury events involving vulnerable road users (VRUs), such as cyclists and moped riders. There have been calls for improvements to the evaluation of safety interventions due to methodological problems associated with the most commonly used study designs. The purpose of this licentiate thesis was to assess the strengths and limitations of the interrupted time series (ITS) design, which has gained some attention for its ability to provide valid effect estimates. Two national road safety interventions involving VRUs were selected as cases: the Swedish bicycle helmet law for children under the age 15, and the tightening of licensing rules for Class 1 mopeds. The empirical results suggest that both interventions were effective in improving the safety of VRUs. Unless other concurrent events affect the treatment population at the exact time of intervention, the effect estimates should be internally valid. One of the main limitations of the study design is the inability to identify why the interventions were successful, especially if they are complex and multifaceted. A lack of reliable exposure data can also pose a further threat to studies of interventions involving VRUs if the intervention can affect the exposure itself. It may also be difficult to generalize the exact effect estimates to other regions and populations. Future studies should consider the use of the ITS design to enhance the internal validity of before-after measurements. Traffic-related injuries represent a global public health problem, and contribute largely to mortality and years lived with disability. Over the course of the last decades, improvements to road traffic safety and injury surveillance systems have resulted in a shift in focus from motor vehicle accidents to injury events involving vulnerable road users (VRUs), such as cyclists and moped riders. There have been calls for improvements to the evaluation of safety interventions due to methodological problems associated with the most commonly used study designs. The purpose of this licentiate thesis was to assess the strengths and limitations of the interrupted time series (ITS) design, which has gained some attention for its ability to provide valid effect estimates while accounting for secular trends. Two national interventions involving VRUs were selected as cases: the Swedish bicycle helmet law for children under the age 15, and the tightening of licensing rules for Class 1 mopeds. The empirical results suggest that both interventions were effective. These results are discussed in the light of some methodological considerations regarding internal and external validity, data quality and the ability to fully understand key causal mechanisms behind complex interventions.

Visual Map-based Localization applied to Autonomous Vehicles

Scipedia content — Tue, 26 Jan 2021 16:03:30 +0100

This thesis is carried out in the context of Advanced Driver Assistance Systems, and especially autonomous vehicles. Its aim is to propose a method to enhance localization of vehicles on roads. I suggests using a camera to detect lane markings, and to match these to a map to extract the corrected position of the vehicle.The thesis is divided in three parts dealing with: the map, the line detector and the evaluation. The map is based on the OpenStreetMap data. The line detector is a based on ridge detection. The results are compared with an Iterative Closest Point algorithm. It also focuses on implementing the components under a real-time constraint. Technologies such as ROS, for synchronization of the data, and CUDA, for parallelization, are used.

Estudo de redes ópticas avançadas para aplicação metropolitana-acesso baseadas em comutação fotônica

Scipedia content — Tue, 26 Jan 2021 16:02:55 +0100

Orientadores: Edson Moschim, Felipe Rudge Barbosa Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Elétrica e de Computação Made available in DSpace on 2018-08-29T22:37:51Z (GMT). No. of bitstreams: 1 Martins_Yara_M.pdf: 2385742 bytes, checksum: 97cbf579c80318ec6df7ea6afe2f1d84 (MD5) Previous issue date: 2015 Resumo: Neste trabalho é analisado o desempenho de redes ópticas com arquitetura baseada em chaveamento fotônico aplicado em topologias de malha. O desempenho é avaliado considerando a confiabilidade e a eficácia na entrega dos pacotes ópticos (origem-destino) nas redes metropolitanas de acesso (metro-acesso), tendo como clientes os usuários das redes sem-fio (fiber-wireless, FiWi). Os principais parâmetros utilizados para as análises são: o número médio de saltos (ANH), o atraso médio (Am) e a fração de perda de pacotes (PLF). A combinação desses parâmetros prova que as redes ópticas com arquiteturas baseadas em chaveamento fotônico com topologia em malha apresentam alta vazão, baixo atraso e baixa perda de pacotes. Este trabalho contribui para projetos de redes ópticas metro-acesso flexíveis que atendam à demanda dos usuários com ênfase em tráfego de pacotes, seja no ambiente sem-fio, seja nas próprias redes ópticas, considerando-se também o equilíbrio entre custo e desempenho das redes Abstract: In this work, the performance of optical networks with architecture based on photonic switching and on mesh topologies is analyzed. The performance of networks is evaluate in terms of traffic, reliability and efficiency of optical packets delivery (origin-destination) for metropolitan access networks (metro-access), which have the wireless networks (fiber-wireless FiWi) as customers. The main parameters used for this analysis are the average number of hops (ANH), Delay (Am) and packet loss fraction (PLF). The combination of these parameters proves that optical networks with architecture based on photonic switching and mesh topology provide high efficiency in throughput with low packet loss and delay. Thus, this work contributes to design flexible optical metropolitan networks that meet users¿ demand with emphasis on packet traffic in the wireless environment or in the optical networks, also considering the balance between cost and performance of the network Mestrado Telecomunicações e Telemática Mestra em Engenharia Elétric

Key Factors of Public Attitude towards Sustainable Transport Policies : A Case Study in Four Cities in Sweden

Scipedia content — Tue, 26 Jan 2021 15:57:21 +0100

Urban transport systems are facing seemingly irreconcilable problems.Sustainable transport policies are necessary to address this sustainability challenge. However,their effectiveness highly depends on the public attitude towards them. A method combiningboth qualitative and quantitative research was used to redefine a sustainable transport policybased on sustainability principles, and find out the key factors of public attitude towardssustainable transport policies. Furthermore, the interrelations between these factors arerevealed by using structural equation modelling. 1685 questionnaires were sent to fourrepresentative cities in Sweden: Stockholm, Göteborg, Uppsala and Karlskrona. By using thisfirst hand data, we discovered some differences between Karlskrona and these other threecities. The negative attitudes towards reducing car use and promoting public transport inKarlskrona is opposite to the positive attitudes in other cities. The acceptance of taxes, speedlimitation and parking regulation is notably different as well. The results also indicate that citycharacteristics influence public attitudes towards sustainable transport policies more thancitizens’ characteristics. The functionality of a city is the most significant factor. Moreover,the results show a high dependence on individual car use. This suggests that planners shouldnot use the experience gained from other cities without investigating actual local conditions.

European airspace measures towards a more sustainable ATM

Scipedia content — Tue, 26 Jan 2021 15:54:46 +0100

The following work will be aiming to investigate the level of how the airspace is being operated under the current conditions and propose the most appealing way to be implemented in order to meet the requirements of capacity increase. Air Traffic Management operates a set of services aiming primary at ensuring safety of flights. The services in Europe are provided by various ATM systems, including controllers, control centers and airports, managing approximately of 30000 daily flights and providing aircraft separations, collision preventing and providing information. The assuring predictions made for the year 2030, is estimated for Air Traffic to double. If nothing will be done we are to be expected, flight cancellations, missed connections and negative impact on safety. Traffic growth cannot be sustained with the current divided air navigation services organization and some ageing ATM technologies. It must be recognized that the air transport must be grown in a sustainable manner, where the future of European ATM system will cope with expected growth in air Traffic. There is a need for one simplified European framework to cope safely with the increased demand. Hence a new Air Traffic Management System is required for the benefit of the European Sky. The possible solutions for the traffic management is provided by SESAR, the goal of which is to enable EU skies to handle 3 times more traffic, improving safety of flights and decreasing of ATM cost and cost per flight. The creating of change of change in European ATM will demonstrate the ability to deliver benefits to the Air Transport community. A performance-based approach will be used for the development of the future ATM system, with common objective: to handle up to three times more traffic than today and decrease in ATM cost per flight. (by 2020) The area navigation and navigation performance specifications have to be globally harmonized for a set of Performance Based Navigation, which defines the performance requirements for aircraft navigation within the Air Traffic Service route. By simulating the possible outcome for the future planning, we will look into how or which of the ways is more attractive to be applied in order to meet the requirements of increasing capacity, in the airspace field. For this we will use Nest desktop application, used by the EUROCONTROL, for airspace structure design and development, preparing scenario for fast and real time simulation. Nest is a scenario-based tool, where we can make changes to the original dataset scenario to model an unlimited number of different operation planning options, also to generate future traffic samples using traffic growth forecasts provided by STATFOR (Statistics and Forecasts). Data will be taken from the Demand Data Repository project, objective of which is to provide airspace users with the a potential accurate outcome of the past and future European air traffic demand, to meet their planning and monitoring needs.

Conceito e dimensionamento de recursos de voz e sinalização em redes de nova geração

Scipedia content — Tue, 26 Jan 2021 15:51:56 +0100

Orientador: Michel Daoud Yacoub Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Elétrica e de Computação Made available in DSpace on 2018-08-27T09:49:57Z (GMT). No. of bitstreams: 1 Silveira_LorenoMenezesda_M.pdf: 2626161 bytes, checksum: b80454b10dc90baf554cb0f37c6ba67e (MD5) Previous issue date: 2015 Resumo: Esta dissertação apresenta uma visão da evolução das redes de telecomunicações objetivando o atendimento dos parâmetros da Qualidade de Serviço de redes IP aos requisitos de qualidade de voz das redes telefônicas de circuitos comutados. Gera também uma série de resultados úteis para planejar a introdução de novas tecnologias e de Redes de Nova Geração (NGN) para serviços de voz. Entre os resultados, introduz uma metodologia de planejamento de rede com base na experiência do autor na área. A aplicação desta metodologia é descrita em um caso de estudo sobre a introdução do serviço de voz através de uma rede IP existente. Analisa parâmetros de qualidade de serviço, requisitos de qualidade de voz e, finalmente, calcula a taxa de transferência de fluxo de dados adicional devido ao tráfego de voz. Os cálculos são baseados em um modelo de dimensionamento implementado em uma planilha do Excel. Apesar de não mostrado neste trabalho, os resultados provaram sua efetividade e consistência com a implantação de uma prestadora específica e com o comportamento subsequente da rede em cidades relevantes, como São Paulo, Rio de Janeiro e Belo Horizontes. A dissertação também apresenta modelos de dimensionamento para o tráfego de sinalização: Sistema de Sinalização Nº 7 (ISUP - Rede Digital de Serviços Integrados e BICC - Portador de Controle de chamada Independent) para uso em redes TDM (Time Division Multiplex), ATM (Asynchronous Transfer Mode) ou NGN, explorando estes modelos de aplicação para o protocolo H.248 com possível extensão a SIP, ambos usados no contexto NGN Abstract: This dissertation provides an overview of telecommunication networks evolution in the light of compliance of IP networks Quality of Service¿s parameters with Public Switched Telephone Networks (PSTN) voice quality requirements. It also delivers a number of new results useful for planning and designing the introduction of new technologies as well as Next Generation Networks (NGN), to provide voice services. Among the results, it introduces a network planning methodology based on the author's experience in this area. The application of such methodology is depicted in a study case concerning the introduction of the voice service over an existing IP network. It analyzes Quality of Service parameters, voice quality requirements and, finally, it calculates the additional data flow throughput due to the voice traffic. The calculations are based on a dimensioning model implemented in an excel spreadsheet. Although not being shown here, the results have been proved effective and consistent with a specific carrier deployment and subsequent network behavior in relevant cities like São, Paulo, Rio de Janeiro and Belo Horizonte. This work also presents a dimensioning model for signaling traffic: Signalling System Nº 7 (ISUP ¿ Integrated Services Digital Networks and BICC - Bearer Independent Call Control) for use in TDM (Time Division Multiplex), ATM (Asynchronous Transfer Mode) or NGN networks. Furthermore, it exploits the application of the dimensioning model to H.248 protocol, suggesting how to extend it to SIP, both used in the NGN context Mestrado Telecomunicações e Telemática Mestre em Engenharia Elétric

Effectiveness of traffic congestion management on intersection delay

Scipedia content — Tue, 26 Jan 2021 15:49:20 +0100

Kokpit Otomasyonu Tabanlı 4d Rota Planlaması

Scipedia content — Tue, 26 Jan 2021 15:45:24 +0100

Tez (Yüksek Lisans) -- İstanbul Teknik Üniversitesi, Fen Bilimleri Enstitüsü, 2015

Thesis (M.Sc.) -- İstanbul Technical University, Institute of Science and Technology, 2015

Hava trafik yönetimi teknolojilerindeki mevcut sistemlerin dönüşümü göz önüne alındığında, gelecek uçuş operasyonlarının ve kokpit içi sistemlerin yeni aviyonik sistemlere ve operasyonel prosedürlere ihtiyaç duyacağını söylemek mümkündür. Özellikle adaptif algoritmalar ve gelişmiş karar destek sistemleri bu ihtiyaçların temelini oluşturmaktadır. Bu konseptlerin hayata geçirilmesi Hava Trafik Yönetimi kapsamında görevlerin ve sorumlulukların değişmesinde büyük rol oynayacaktır. En iyi karar yeri, en iyi karar zamanı ve en iyi karar veren bu bağlamda temel faktörlerdir. Örneğin; kontrolcüler hava trafiğini yönetmede yüksek derecede rol sahibi olacak ve bireysel rotalara müdahale sayısını azaltacaklardır. Pilotlar uçuş esnasında daha aktif olacak; çevreyi gözlemleme ve yönetme, seçenekleri analiz ete veya gerektiği durumda ayırma manevrası uygulama gibi önemli görevlerde daha çok görev alacaktır. Uçuş ekibinin rolündeki bu değişimler mevcut görevlerin yeniden tanımlanmasına gidilmesinin yanı sıra insan faktörü performansını da etkileyecektir. Geleceğin kokpit içi sistemlerinde uçuş ekibinin bu yeni görevleri başarıyla gerçekleştirmesini sağlayan yeni nesil cihazlar ve algoritmalar gerekecektir. Bu tez kapsamında yapılan ilk çalışma, yeni nesil sentetik vizyon ve artırılmış gerçeklik tabanlı görselleştirme teknolojileri kullanılarak görsel kokpit içi karar destek araçları ve arayüzleri tasarımıdır. Dizayn edilen bu araçların NextGen ve SESAR 2020+ programlarında tanımlanmış gelecek uçuş operasyonlarının gereksinimlerini karşılaması amaçlanmaktadır. Bu aviyonik sistemler ile pilotların niyet paylaşımı/pazarlığı ile işbirlikçi taktiksel planlama, çözümleri alternatifleri ile birlikte tam olarak anlama/analiz etme/yorumlama ve yeni çözüm önerme gibi uçuş operasyonlarında desteklenmesi vizyonlanmıştır. Ek olarak, gerekli cevabın farkında olma, uygulama veya çarpışma önleyici sisteme otomasyon yetkisi verme gibi görevlerde de karar destek sağlanması hedeflenmiştir. Görsel karar destek sistemleri uçuş ekibinin yeni otonom sistemler ile etkileşimini ve tüm taktiksel veriyi görselleştirerek içinde bulunulan durumu veya gelişmekte olan uçuş operasyonunu anlaşılır olmasını mümkün kılmaktadır. Bu proje kapsamında iki farklı görsel yapı sunulmaktadır. Kokpitin Primary Flight Display bölgesinde yer alan sentetik vizyon ekran çifti pilotların 4D ortamda durum farkındalığı ile düşük ve yüksek seviyede taktiksel görevleri yönetmesini sağlamaktadır. SVD kısmı pilota yapay görsellik sağlamakla beraber gerekli güdüm, uçuş ve kısıtlı seviyede operasyonel bilgileri içermektedir. Tunnel-in-the-sky konsepti ile pilot, odaklanılan veya karar verilen rotayı tüneller aracılığıyla manuel olarak takip edebilir. Bununla beraber standart sentetik vizyon (sanal gerçeklik) ekranı fonksiyonlarını da kullanabilir. İrtifa ve hız bilgileri, radar frekans değerleri, harita ve yükselti bilgisi, hava koşulları gibi temel uçuş operasyonu verisi bu ekranda gösterilmektedir. 4D Operasyonel Ekranı (4DOD) operasyon durumu ile ilgili farkındalığı artırmak ve uçuş niyeti üzerindeki modifikasyonları göstermek üzere yüksek seviyede operasyonel bilgileri sağlamaktadır. Pilot, hem kendi yörüngesini kontrol edebilmekte hem de trafikteki uçaklara ait rotaları izleyebilmektedir. Aynı zamanda ileriye dönük hızlandırılmış simulasyon fonksiyonu da bulunmaktadır. Kokpitin veri bağlantısı üzerinden yer ile rota ve uçuş planı paylaşımı sürecinin yönetilmesi bu ekran aracılığıyla olmaktadır. Haptik arayüzler ile uçuş ekibi gösterilen bilgileri ve görselleri 2D+zaman ve 3D+zaman boyutunda yönetebilmektedir. Sentetik vizyon ve 4DOD ekran çiftine paralel olarak pilotun görüş hizası üzerine inşa edilmiş Head-up Display (HUD)bulunmaktadır. HUD aracılığıyla pilot benzer şekilde temel uçuş durum bilgilerini aşağıya bakma gereği duymadan izleyebilmekte, tunnel-in-the-sky konsepti sayesinde hedef yörüngeyi tüneller arasından uçmaya çalışarak takip edebilmektedir. Bu görsel karar destek sistemleri ve algoritmalarının donanım olarak entegrasyonu, Boeing 737-800 uçuş simulatörü üzerinde gerçekleşmiştir. Sentetik vizyon ve 4DOD ekran çifti Primary Flight Display (PFD) monitörleri üzerinde çizdirilmiştir. Head-up Display (HUD), kaptan pilot ile ön cam arasına yerleştirilmiştir. Özel bir film kullanılarak görüntü arkadan mini-projeksiyon cihazı aracılığıyla yansıtılmıştır. Her bir görsel karar destek sistemi simulatörün ağına bağlanmış olup veri akışını kontrol eden ve yöneten algoritmalar düzenlenmiştir. Uçuş simulatörü, Hava Trafik Kontrolü test ortamı ile birleştirilerek geliştirilen yeni nesil aviyonik konseptlerinin uçuş operasyonları üzerindeki etkileri resmedilmiştir. Hava Trafik Kontrolü test ortamı trafik ve hava durumu tasarlayıcı, Hava Trafik Kontrol ekranları ve kontrolörün davranışının benzetim çalışmalarını yapan modellerden oluşmaktadır. Test ortamı aynı zamanda ALLFT+ tabanlı geçmiş uçuşlara ait gerçek veri kullanarak önceden belirlenmiş veya düzenlenebilen senaryoların oynatılmasını sağlamaktadır. Trafik ve hava durumu tasarlayıcı modül Demand Data Repository veritabanı üzerinden beslenen havaalanı ve hava sahası kapasite bilgilerini ve Aeronautical Information Publication'dan gelen operasyonel bilgileri içermektedir. Benzer şekilde, modifiye edilmiş senaryolar veya geçmiş hava durumu bilgileri METAR verisi üzerinden aktarılmaktadır. Test ortamı günümüz hava trafik kontrol ekranları, ses ile iletişim, otonom veya karar destekli kontrol operasyonlarını ifade eden modeller aracılığı ile hem günümüz operasyonlara hem de geleceğe yönelik çalışmalara ait senaryoları koşabilmektedir. Projenin ikinci aşaması ve ana amacı ise taktiksel 4D yörünge planlaması ve otomasyon araçları ile donatılmış uçak için "conflict resolution", ya da potansiyel çarpışma önleyici ve bunu otonom olarak yapan sistemler için teorik çerçeve tasarlanmasıdır. Yoğun trafik ortamında veya yeni rota hesaplanması gibi durumlarda yerden bağımsız, uçak üzerinde ve otonom olarak hem gerçeklenebilir, hem de maliyeti düşük rotaların üretilmesi istenmektedir. Önerilen 4D yörünge planlama metodu hem olasılıksal hem de deterministik algoritmaların yeni özelliklerini içermekle beraber iki yöntemin de başarılı taraflarını birleştirmektedir. Uçak performans modeli ise yörünge tayini için gerekli bir bileşen olup BADA 4 üzerinden sağlanmaktadır. Uçağın kinodinamik modellemesinde standart yörünge uygulamalarında kullanılan 3-serbestlik dereceli veya diğer adıyla nokta kütle hareket modeli kullanılmıştır. Bu modelde uçağın hali hazırda kendi içerisinde kararlı ve kontrol edilebilir olduğu kabul edilip, takip ettiği yörünge ile ilgilenilmektedir. Uçağa etkiyen kuvvetlerin veya uçak performansının modellenmesi EUROCONTROL'ün bir ürünü olan Base of Aircraft Data (BADA) aracılığıyla yapılmıştır. Projede son sürüm olan BADA 4 kullanılmıştır. Bu versiyon, öncekilerden farklı olarak uçağa etkiyen kuvvetleri uçağın durumları ve atmosfer koşullarına bağlı olarak parametrik ifade etmektedir. Teknik altyapısını Boeing'in sağladığı bu veritabanı, gelişmiş modellemeleri sayesinde nominal değerlerin üzerine çıkarak parametre öngörmesi ve optimizasyon gibi işlemleri yapılabilir kılmaktadır. Oluşturulan bu performans modeli yüksek-seviye hibrid uçuş kalıpları otomatları ve alçak-seviye manevra otomatlarını kapsamaktadır. Bu modellemedeki amaç, uçak hareketini tırmanma, seyir ve alçalma şeklinde üç farklı kalıp altında toplamaktır. Her bir uçuş kalıbı kendine özel manevra sekansı içermektedir. BADA 4 matematiksel modelleri aracılığıyla her bir uçuş kalıbı için tanımlı manevra sekansını düşük maliyet ile gerçekleştiren parametreler öngörülmüştür. Esasında bu problem, bir uçağın başlangıç ve bitiş olarak verilen iki nokta arasında en düşük maliyetli rotayı takip etmesi problemidir. Uçak denklemlerinin ve kısıtlamaların lineer olarak ifade edilememesi, bu problemin tek bir seferde global olarak çözülmesini zorlaştırmaktadır. Ek olarak bu modülün uçak üzerinde çalışacağı düşünülecek olursa bu hesaplamaların çok kısa zaman aralıklarında gerçekleşmesi beklenmektedir. Çok-modlu yaklaşım sayesinde kompleks olan yörünge planlama problemini global olarak çözmek yerine lokal ve düşük maliyetli yörüngeler tayin edilmektedir. Bu noktadaki dezavantaj ise yaklaşımın verdiği çözümün optimum değerden uzaklaşmasıdır. Daha üst seviyede ise hesaplanan düşük maliyetli lokal rota parçaları oluşturan ve uzayı tarayan RRT* algoritması kullanılmıştır. RRT*,örnekleme tabanlı bir hareket planlama algoritması olup hava sahasını keşfetmeye çalışarak lokal yörünge segmentleri üzerinden ayırma yapmaktadır. İlk adım olarak uzayda bir konum örnekleyip, ardından uçuş kalıpları ve gelişmiş performans modelini kullanarak uçağı bu noktaya düşük maliyet ile getirmeye çalışmaktadır. Örneklenen konuma, mesafe olarak ağaçta hali hazırda bulunan en yakın konumdan bağlanmaya çalışılır. Bu, arama uzayının hızlı ve ilerleyerek keşfedilmesinin temelidir. Lokal maliyetlerin yanında başlangıç konumundan itibaren harcanan maliyet de hesaba katıldığı için ağaç sürekli olarak toplam maliyeti düşük olan uçuş segmenti sekanslarını üreterek büyür. Önceden belirlenmiş örnekleme sayısına ulaşıldığında algoritma durur. Kullanılan algoritma aynı zamanda belirli koşullar altında asimptotik optimalliği sağlamaktadır. Asimptotik optimallik, örnekleme sayısı sonsuza yaklaştıkça problemin optimal çözüme yakınsama özelliğidir. RRT* aynı zamanda olasılıksal bütünlüğü sağlamaktadır: Örnekleme sayısı sonsuza yaklaştıkça çözüm bulma olasılığı 1'e yakınsamaktadır. Bunlara ek olarak, örnekleme için cross-entropy yöntemi kullanılmıştır. Bu yöntem ile örnekleme problemi stokastik optimizasyon problemine dönüştürülerek hızlı bir şekilde minimum maliyetli yörünge sekansı oluşturulmuştur. Akıllı örnekleme yapılırken halihazırdaki uçuş planları kullanılmış, dolayısıyla örnekleme sayısının düşük tutulabilmesi sağlanmıştır. Standart rastgele örnekler almak yerine daha akıllı örnekleme yapmak, optimum sonuca daha çabuk ulaşılmasını sağlamıştır. Ancak, her adımda oluşturulan küme içinden ağırlıklandırması yüksek olan elit set çekildiği için hesaplama yükü artmıştır. Proje kapsamında hem Avrupa'nın hem Amerika'nın hava trafik yönetimi konusunda yaptığı kapsamlı araştırmalar incelenmiş ve buradaki trendler takip edilmiştir. Hava trafik yönetiminde kapasiteyi artırmak üzere yer kontrolcülerinin görevlerini daha çok genel akışı yönetmesi vizyonlanmış; pilotların ise daha çok aktif rol aldığı bir dünya çizilmiştir. Pilotlara karar vermelerinde destek olacak görsel sistemler tasarlanmış, yer ile uçağın aynı anda işbirlikçi bir biçimde uçuş operasyonunu yönettiği konseptler eklenmiştir. Bunların yanında çarpışmaları gözleyen ve gerektiği durumda otonom ayırma yapabilen sistemler için algoritma tasarlanmıştır. Geleceğin hava trafik koşullaru vizyonlanarak göz önünde bulundurulmuş, önerilen yöntemin hem bugünün hem de geleceğin hava trafik yönetim sistemine katkı sağlaması amaçlanmıştır.

Considering the transformation in roles of existing air traffic management technologies, future flight operations and flight deck systems will need additional avionics and operational procedures that involve adaptive algorithms and advanced decision support tools. The first part of the thesis presents novel visual flight deck decision support tools and interfaces utilizing next generation synthetic vision and augmented reality based visualisation technologies in order to meet the requirements of the future flight operations defined in NextGen and SESAR 2020+ visions. These avionics are envisioned to aid pilots for conducting their new in-flight tasks such as; collaborative tactical planning with intent negotiation/sharing; fully understanding/analysing/interpreting solution with their alternatives and proposing modification on the solution subject to negotiation; and aware of required response, execute it or allow collision avoidance module to perform its automated response. Visual Decision Support Tools allow the flight crew to interact with new autonomous systems and provide with visual understanding on the evolving flight operation by fusing all tactical level data and visualising them. In this work, two groups of display structure have been proposed. A split head-down \\textit{Synthetic Vision} screen pair aims to support the pilots in managing both low level and high level tactical tasks with fully understanding the situation in 4D. Synthetic Vision Display (SVD) side provides the pilots synthetic vision and also incorporates required additional guidance and limited operational information. 4D Operational Display (4DOD) provides higher level operational information giving building enhanced understanding on the states of the operation and results of any modification on processing flight intent. Haptic interfaces allow the flight crew to change demonstrated detail levels in both 2D+time and 3D+time. The other display, which is \\textit{Head-Up-Display (HUD)}, provides pilot to efficiently operate flight operation by eliminating the need of looking to head-down screen; and aims to present all essential flight information in the pilot's forward field through augmented reality implementations. For hardware integration and experimental purposes, an integrated testbed including full replica B737-800 Flight Deck Testbed and ATM Testbed has been modified as enabling operational tests and validations of these new tools. The main purpose of this study is to provide a theoretical framework for tactical 4D-trajectory planning and conflict resolution of an aircraft equipped with novel automation tools. The proposed 4D-trajectory-planning method uses recent algorithmic advances in both probabilistic and deterministic methods to fully benefit from both approaches. We have constructed an aircraft performance model based on BADA 4 with high-level hybrid flight template automatons and low-level flight maneuver automatons. This multi-modal flight trajectory approach is utilized to generate cost-efficient local trajectory segments instead of solving complex trajectory-generation problems globally. The proposed sampling-based trajectory planning algorithm spatially explores the airspace and provides proper separation through local trajectory segments and guarantees asymptotic optimality under certain conditions. Moreover, we have integrated the cross-entropy method, which transforms the sampling problem into a stochastic optimization problem, rapidly converges on the minimum cost trajectory sequence by utilizing available flight plans, and reduces the amount of sampling. The integration of the proposed strategies lets us solve challenging, real-time in-tactical 4D-trajectory planning problems within the current and the envisioned future realm of air traffic management systems.

Yüksek Lisans

M.Sc.

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Network virtualization and traffic engineering in Software-Defined Networks

Scipedia content — Tue, 26 Jan 2021 15:34:42 +0100

[ANGLÈS]Lately, the emerging paradigm of Software-Defined Networking has grown in presence and claims to simplify future networking. The decoupling of network control and forwarding plane proposed by this architecture allows the control of the entire network behavior by means of a logically centralized software program (controller). Such separation of planes opens the way to Network Virtualization, which provides users a logical abstraction of underlying network resources. However, network virtualization requires a mapping phase of the virtual resources over the physical resources, which is not trivial, formally known as the virtual network embedding problem. The present document focuses in the development of a variant of one of the proposed strategies to solve this critical step, prioritizing the real-time response. The proposed algorithm uses the properties offered by the Paths Algebra mathematical framework to provide a flexible environment where it is possible to combine any number of both linear and non-linear metrics. In addition, it is also used the multi-lexical ordination, a criterion to better distinguish paths that may be considered equal by other approaches. Such algorithm has been implemented as a software application that provides a simulation environment where the virtual network embedding process can be tested for any given topology. Subsequently, all the algorithm features have been checked in a set of performance tests, focusing on those oriented to the commitment among the real-time response and the quality of the embedding solutions. In general, testing results are very promising even in densely populated backbone topologies, where the number of alternative paths among each possible pair of origin and destination nodes grows exponentially.

[CASTELLÀ] Software-Defined Networking (o Redes Definidas por Software) es un nuevo paradigma que tiene como objetivo simplificar la creación y gestión de redes de ordenadores. El desacoplamiento entre el control de la red y el plano de reenvío propuesto por esta arquitectura permite el control de todo el comportamiento de la red mediante un elemento lógico centralizado, llamado controlador. Esta separación de los planos abre la puerta a la virtualización de redes, proporcionando a los usuarios una abstracción lógica de los recursos de red subyacentes. Sin embargo, la virtualización de red requiere de una fase de asignación de los recursos virtuales a los recursos físicos, que no es trivial y que se conoce formalmente como el problema de incrustación de redes virtuales. El presente documento se centra en el desarrollo de una variante de una de las estrategias propuestas para resolver este paso crítico, dando prioridad a la respuesta en tiempo real. El algoritmo propuesto utiliza las propiedades ofrecidas por el marco matemático de Paths Algebra (o Álgebra de Caminos) para proporcionar un entorno flexible donde es posible combinar cualquier número de métricas lineales y no lineales. Además, también utiliza la ordenación multi-léxica, un criterio para distinguir mejor aquellos caminos que podrían ser considerados equivalentes por otros enfoques. Este algoritmo se ha implementado como una aplicación de software que proporciona un entorno de simulación en el que se puede probar el proceso de incrustación de redes virtuales para cualquier topología. Posteriormente, se han comprobado todas las características del algoritmo mediante un conjunto de pruebas de rendimiento, priorizando aquellas orientadas al compromiso entre la respuesta en tiempo real y la calidad de las soluciones de incrustación. En general, los resultados de las pruebas son muy prometedores incluso en topologías de redes troncales densamente pobladas, donde el número de caminos alternativos entre cada posible nodo origen y destino crece exponencialmente.

Optical Flow in Driver Assistance Systems

Scipedia content — Tue, 26 Jan 2021 15:33:24 +0100

El moviment és un atribut perceptiu del cervell humà molt important. La percepció visual que fa el cervell del moviment és el procés d’inferir la velocitat i direcció dels elements d’un escenari mitjançant entrades visuals. Anàlogament, la visió per computador s’assisteix mitjançant informació del moviment de l’escena. En visió per computador, la detecció de moviment és útil per a resoldre problemes com per exemple segmentació, estimació de la profunditat, estimació de l’estructura a partir del moviment, compressió de dades o navegació entre d’altres. Aquests problemes són comuns a diferents aplicacions, com ara vídeo vigilància, navegació de robots i sistemes avançats d’assistència a la conducció (Advanced Driver Assistance Systems, ADAS). Una de les tècniques més utilitzades per a detectar moviment, és el càlcul d’optical flow. El treball tractat en aquesta tesi pretén que les formulacions d’optical flow siguin més apropiades als requeriments i condicions dels escenaris de conducció. En aquest context, es proposa una nova representació de l’espai-variant anomenada representació reverse log-polar, i es demostra que, quan s’utilitza per a ADAS, té un rendiment millor que la tradicional representació log-polar. La representació espai-variant redueix la quantitat de dades necessàries que han de ser processades. Una altra contribució important està relacionada amb l’anàlisi de la influència de les característiques específiques d’escenaris de conducció per a la precisió de l’optical flow. S’han considerat característiques tals com la velocitat del vehicle i la textura de la carretera. D’aquest estudi s’infereix que, el pes del terme de regularització s’ha d’adaptar segons una mesura d’error i per a diferents velocitats i textures de la carretera. També es mostra que la representació polar d’optical flow funciona molt millor per a escenaris de conducció on el moviment principal són translacions. Degut als requeriments d’aquest estudi, i per la manca de bases de dades es presenta una nova base de dades sintètica que conté: i) seqüències amb diferents velocitats i textures en un escenari urbà; ii) seqüències amb moviments complexos de la càmera col·locada al vehicle; i iii) seqüències amb altres vehicles en moviment dintre la mateixa escena. L’optical flow corresponent a cada seqüència s’obté mitjançant la tècnica de ray-tracing. A més a més, es presenten algunes aplicacions per a optical flow en escenaris ADAS. Per començar, proposem una tècnica robusta basada en RANSAC per estimar la línia de l’horitzó. Després, presentem una estimació de l’egomotion per a comparar la representació espai-variant proposada amb les representacions clàssiques. Com a contribució final, es proposa una modificació del terme de regularització que millora notablement els resultats per a aplicacions d’ADAS. Aquesta adaptació s’avalua mitjançant tècniques d’optical flow d’última generació. Els experiments realitzats amb una base de dades pública (KITTI) validen els avantatges d’utilitzar la modificació proposada.

La percepción del movimiento es uno de los más importantes atributos del cerebro humano. La percepción visual del movimiento consiste en inferir velocidad y dirección de los elementos móviles que interactúan en una escena, mediante la interpretación de diferentes entradas visuales. Análogamente, la visión por computador hace uso de la información del movimiento en la escena. La detección de movimiento en visión por computador es útil para resolver problemas tales como: segmentación, estimación de profundidad, compresión, navegación, entre otros. Estos problemas son comunes en distintas aplicaciones, por ejemplo: video vigilancia, navegación de robots y sistemas avanzados de asistencia a la conducción (ADAS). Una de las técnicas más utilizadas para detectar movimiento es la estimación del flujo óptico. El trabajo abordado en esta tesis busca formulaciones del flujo óptico más adecuadas a las necesidades y condiciones de los escenarios de conducción. En este contexto, se propuso una novedosa representación del espacio, llamada representación inversa log-polar, la cual se demuestra que tiene un desempeño mejor que la tradicional representación logpolar para aplicaciones ADAS. Las representaciones de espacio-variante reducen la cantidad de datos a ser procesados. Otra contribución importante está relacionada con el análisis de la influencia de las características específicas de los escenarios de conducción en la precisión del flujo óptico estimado. Características tales como la velocidad del vehículo y la textura de la carretera son consideradas en el estudio. De este estudio, se infiere que el peso del término de regularización tiene que ser adaptado de acuerdo con la medida de error requerida y para diferentes velocidades y texturas de la carretera. También se concluye que la representación polar del flujo óptico es la más apropiada en escenarios de conducción, donde el movimiento predominante es la translación. Debido a las exigencias de tal estudio, y por falta de las bases de datos necesarias, se presenta un nuevo conjunto de datos sintéticos el cual contiene: i) secuencias de diferentes velocidades y texturas en un escenario urbano; ii) secuencias con movimientos complejos de la cámara dispuesta en el vehículo; y iii) secuencias con otros vehículos en movimiento en la escena. El flujo óptico correspondiente a cada secuencia es obtenido mediante una técnica de ray-tracing. Adicionalmente, se presentan algunas aplicaciones de flujo óptico en ADAS. Primeramente se propone una técnica robusta basada en RANSAC para estimar la línea de horizonte. Seguidamente se presenta una estimación del egomotion para comparar la representación de espacio-variante propuesta con los esquemas clásicos. Como contribución final, se propone una modificación en el término de regularización que mejora notablemente los resultados en las aplicaciones ADAS. Los resultados experimentales en una base de datos pública (KITTI) validan las ventajas de la utilización de la modificación propuesta.

Motion perception is one of the most important attributes of the human brain. Visual motion perception consists in inferring speed and direction of elements in a scene based on visual inputs. Analogously, computer vision is assisted by motion cues in the scene. Motion detection in computer vision is useful in solving problems such as segmentation, depth from motion, structure from motion, compression, navigation and many others. These problems are common in several applications, for instance, video surveillance, robot navigation and advanced driver assistance systems (ADAS). One of the most widely used techniques for motion detection is the optical flow estimation. The work in this thesis attempts to make optical flow suitable for the requirements and conditions of driving scenarios. In this context, a novel space-variant representation called reverse log-polar representation is proposed that is shown to be better than the traditional log-polar space-variant representation for ADAS. The space-variant representations reduce the amount of data to be processed. Another major contribution in this research is related to the analysis of the influence of specific characteristics from driving scenarios on the optical flow accuracy. Characteristics such as vehicle speed and road texture are considered in the aforementioned analysis. From this study, it is inferred that the regularization weight has to be adapted according to the required error measure and for different speeds and road textures. It is also shown that polar represented optical flow suits driving scenarios where predominant motion is translation. Due to the requirements of such a study and by the lack of needed datasets a new synthetic dataset is presented; it contains: i) sequences of different speeds and road textures in an urban scenario; ii) sequences with complex motion of an on-board camera; and iii) sequences with additional moving vehicles in the scene. The ground-truth optical flow is generated by the ray-tracing technique. Further, few applications of optical flow in ADAS are shown. Firstly, a robust RANSAC based technique to estimate horizon line is proposed. Then, an egomotion estimation is presented to compare the proposed space-variant representation with the classical one. As a final contribution, a modification in the regularization term is proposed that notably improves the results in the ADAS applications. This adaptation is evaluated using a state of the art optical flow technique. The experiments on a public dataset (KITTI) validate the advantages of using the proposed modification.

Jitneys, Buses, and Public Transportation in Twentieth Century Los Angeles

Scipedia content — Tue, 26 Jan 2021 15:27:42 +0100

This project uncovers the role of buses and their riders in shaping Los Angeles urban history in two crucial moments. First, while the private automobile inexorably altered American mobility, the bus quietly became the dominant form of public transit, replacing streetcars by the mid-1950s. I argue the jitney (the precursor to the bus, a short-lived owner/operator business phenomenon throughout the U.S. in the 1910s) directed the shift into automobile-based public transportation by giving riders a choice in transit, ultimately resulting in the end of interurban rail service. Secondly, the movement into public ownership of mass bus transit in the 1950s was inspired in part by riders, resulting in the municipally-directed systems we now find common. This decision to create publicly-owned public transportation occurred in the post-WWII context of Cold War fears of government oppression and socialism, marking transportation as something of an outlier in the cultural construction of social and municipal responsibility. Still, the limitations placed upon transit by Angelinos in the form of funding and planning failures ultimately reinforces the skepticism of government as a provider of services.The dissertation intends to prove that riders directed the movement into road-based public transportation in a quest for more efficient transportation that met their needs more effectively than urban rail. It further analyzes the moral and ethical implications of why 1950s Los Angeles--amid a historical moment actively promoting private mobility in the form of massive federal and state highway programs--chose to assume public control of an erstwhile private industry. Public ownership changed the sort of access into transportation planning and operation, allowing ethical and moral issues (such as the social effect of fare increases, union activity, and unprofitable route service into low income areas) to challenge the dollars-and-cents approach to transportation planning previously, and unsuccessfully, embraced by private ownership. Although the boundaries placed upon public transit by citizens of Los Angeles ultimately emphasize ideas of limited government (in keeping with other Cold War-period studies of American culture), the assumption of public transportation under public ownership in the 1950s was an important change in the cultural interpretation of transit as a social responsibility, rather than a private entrepreneurial opportunity.In each step of this dissertation, riders are the primary catalyst, directing the changes in transit through market forces, through choice in the technology they preferred, or through funding of transit projects. Despite all the urban planning and top-down transit schemes--private or public--riders retained the ability to reshape transit in L.A. in the twentieth century through each moment of the city's transportation history.

Elektrikli Araç Şarj Yüklerinin Raslantısal Benzetimi Ve Alçak Gerilim Dağıtım Şebekesine Etkisi

Scipedia content — Tue, 26 Jan 2021 14:34:44 +0100

Tez (Yüksek Lisans) -- İstanbul Teknik Üniversitesi, Fen Bilimleri Enstitüsü, 2015

Solution Space-based Approach to Assess Sector Complexity in Air Traffic Control

Scipedia content — Tue, 26 Jan 2021 14:33:41 +0100

Various methods have been introduced in the past in efforts to optimize airspace sector design and the allocation of air traffic controllers. This is done with the aim to accommodate growth, increase productivity and most importantly to ensure safety of air traffic. To accomplish this, a more comprehensive understanding of human workload, especially that of the controllers involved, is required. In Air Traffic Control (ATC), there exists a maximum number of aircraft per sector that the Air Traffic Controller (ATCO) is assumed to be capable of controlling simultaneously. The maximum controllable traffic is gathered based on experimentation and subjective assessments of controller workload, which are sector specific. This threshold is not to be exceeded in order to maintain a reasonable and sustainable level of workload. However, a sector complexity metric based on the maximum number of aircraft does not consider the dynamic nature of air traffic, thus limiting the possibility of accommodating the growth of air traffic. Consequently, to better support strategic decisions that need information on ATC workload, we need better measures than just the number of aircraft. Metrics, for example the Dynamic Density (DD) that use a weighted combination of static and dynamic airspace properties, such as the number of aircraft flying through a sector, the ratio of climbing, cruising and descending aircraft, the horizontal proximity between aircraft et cetera, have been constructed and proposed as a sector complexity measure. The proposed weightings are determined through regression analysis on expert judgement for a particular sector design. As a result, these metrics become highly dependent on sector and operator-centered factors and therefore not uniformly applicable to a wider range of operators and sector designs. A careful calibration would then be needed to tailor the measure to each individual operator and also to the considered sector. In an effort to find a more objective measure of sector complexity and a predictor of workload, this thesis investigates a constraint-based measure based on the Solution Space Diagram (SSD). In essence, the SSD is a method to observe aircraft restrictions and opportunities to resolve air traffic conflicts in both the speed and heading dimensions. The SSD can be described as the available control area for the controlled aircraft in respect to other observed aircraft within the vicinity. The construction of the SSD is based on the projection of the ‘zone of conflict’ of the observed aircraft where the key constraint is the 5 NM separation minimum between aircraft. When considering the SSD for any individual aircraft, all neighboring aircraft introduce a ‘no-go area’ or ‘zone of conflict’ on the SSD. Intrusion of this zone is called a conflict, or, loss of separation. Looking at the results of the numerous off-line and real-time human-in-the-loop experiments, the proposed SSD metric shows a promising prospect of being an objective measure of sector complexity and a viable subjective workload predictor. However, these results are based on specific experiment settings, assumptions, and simplifications that were made throughout the research. Thus, to prove that the method was found to be the most suited metric in measuring sector complexity, a more extensive research regarding its performance and robustness should be done in the future. More comprehensive research on sector complexity has to be done in order to have a better understanding of sector complexity and controller workload. Also, to keep up with the relevance of the current situation, the extension of the SSD to the third dimension is crucial.

Detecção e classificação de objetos em ambientes externos para navegação de um veículo de passeio autônomo utilizando fusão de dados de visão artificial e sensor laser

Scipedia content — Tue, 26 Jan 2021 14:32:38 +0100

This research project took part in the SENA project (Autonomous Embedded Navigation System), which was developed at the Mobile Robotics Lab of the Mechatronics Group at the Engineering School of São Carlos, University of São Paulo (EESC - USP) in collaboration with the São Carlos Institute of Physics. Aiming for an autonomous behavior in the prototype vehicle this dissertation focused on deploying some machine learning algorithms to support its perception. These algorithms enabled the vehicle to execute articial-intelligence tasks, such as prediction and memory retrieval for object classication. Even though in autonomous navigation there are several perception, cognition and actuation tasks, this dissertation focused only on perception, which provides the vehicle control system with information about the environment around it. The most basic information to be provided is the existence of objects (obstacles) around the vehicle. In formation about the sort of object it is also provided, i.e., its classication among cars, pedestrians, stakes, the road, as well as the scale of such an object and its position in front of the vehicle. The environmental data was acquired by using a camera and a Velodyne LiDAR. A ceiling analysis of the object detection pipeline was used to simulate the proposed methodology. As a result, this analysis estimated that processing specic regions in the PDF Compressor Pro xii image (i.e., Regions of Interest, or RoIs), where it is more likely to nd an object, would be the best way of improving our recognition system, a process called image normalization. Consequently, experimental results in a data-fusion approach using laser data and images, in which RoIs were found using the LiDAR data, showed that the fusion approach can provide better object detection and classication compared with the use of either camera or LiDAR alone. Deploying a data-fusion classication using RoI method can be executed at 6 Hz and with 100% precision in pedestrians and 92.3% in cars. The fusion also enabled road estimation even when there were shadows and colored road markers in the image. Vision-based classier supported by LiDAR data provided a good solution for multi-scale object detection and even for the non-uniform illumination problem. Este projeto de pesquisa fez parte do projeto SENA (Sistema Embarcado de Navegação Autônoma), ele foi realizado no Laboratório de Robótica Móvel do Grupo de Mecatrônica da Escola de Engenharia de São Carlos (EESC), em colaboração com o Instituto de Física de São Carlos (IFSC). A grande motivação do projeto SENA é o desenvolvimento de tecnologias assistidas e autônomas que possam atender às necessidades de diferentes tipos de motoristas (inexperientes, idosos, portadores de limitações, etc.). Vislumbra-se que a aplicação em larga escala desse tipo de tecnologia, em um futuro próximo, certamente reduzirá drasticamente a quantidade de pessoas feridas e mortas em acidentes automobilísticos em estradas e em ambientes urbanos. Nesse contexto, este projeto de pesquisa teve como objetivo proporcionar informações relativas ao ambiente ao redor do veículo, ao sistema de controle e de tomada de decisão embarcado no veículo autônomo. As informações mais básicas fornecidas são as posições dos objetos (obstáculos) ao redor do veículo; além disso, informações como o tipo de objeto (ou seja, sua classificação em carros, pedestres, postes e a própria rua mesma), assim como o tamanho deles. Os dados do ambiente são adquiridos através do emprego de uma câmera e um Velodyne LiDAR. Um estudo do tipo ceiling foi usado para simular a metodologia da detecção dos obstáculos. Estima-se que , após realizar o estudo, que analisar regiões especificas da imagem, chamadas de regiões de interesse, onde é mais provável encontrar um obstáculo, é o melhor jeito de melhorar o sistema de reconhecimento. Observou-se na implementação da fusão dos sensores que encontrar regiões de interesse usando LiDAR, e classificá-las usando visão artificial fornece um melhor resultado na hora de compará-lo com os resultados ao usar apenas câmera ou LiDAR. Obteve-se uma classificação com precisão de 100% para pedestres e 92,3% para carros, rodando em uma frequência de 6 Hz. A fusão dos sensores também forneceu um método para estimar a estrada mesmo quando esta tinha sombra ou faixas de cor. Em geral, a classificação baseada em visão artificial e LiDAR mostrou uma solução para detecção de objetos em várias escalas e mesmo para o problema da iluminação não uniforme do ambiente.

Crew Management in Passenger Rail Transport

Scipedia content — Tue, 26 Jan 2021 14:31:21 +0100

xtabstract__Abstract__ Crew management in passenger rail transport is an important factor that contributes to both the quality of service to the railway passengers and to the operational costs of the train operating company. This thesis describes how the (railway) Crew Management process can be improved with the introduction of advanced decision support systems, based on advanced mathematical models and algorithms. We provide a managerial perspective on the change process, related to the introduction of these systems, and give an overview of the lessons learned. We have shown that introducing decision support can give substantial improvements in the overall performance of a railway company. Within NS, the support for the Crew Management process has led to a stable relationship between management and train crew. In addition, the lead-time of the planning process is shortened from months to hours and NS is now able to perform scenario analyses, e.g., to study effects of adjusting the labour rules. Also, NS can adjust their service when severe weather conditions are expected, by creating a specific winter timetable shortly before the day of operation. Finally, we also introduced a decision support system for real-time rescheduling of crew duties on the day of operations. This enables us to adapt the actual crew schedules very quickly. As a result, we reduce the number of cancelled trains and fewer trains will be delayed in case of unforeseen disruptions.

Driver Behaviour in Highly Automated Driving : An evaluation of the effects of traffic, time pressure, cognitive performance and driver attitudes on decision-making time using a web based testing platform

Scipedia content — Tue, 26 Jan 2021 14:24:26 +0100

Driverless cars are a hot topic in today’s industry where several vehicle manufacturers try to create a reliable system for automated driving. The advantages of highly automated vehicles are many, safer roads and a lower environmental impact are some of the arguments for this technology. However, the notion of highly automated cars give rise to a large number of human factor issues regarding the safety and reliability of the automated system as well as concern about the driver’s role in the system."br/""br/"The purpose of this study was to explore the effects of systematic variations in traffic complexity and external time pressure on decision-making time in a simulated situation using a web-based testing platform. A secondary focus was to examine whether measures of cognitive performance and driver attitudes have an effect on decision-making time."br/""br/" The results show that systematic variations in both time pressure and traffic complexity have an effect on decision-making time. This indicates that drivers are able to adapt their decision-making to facilitate the requirements of a certain situation. The results also indicate that intelligence; speed of processing and driver attitudes has an effect on decision-making time.

Racionalización de la red de autobuses de tránsito rápido (BRT): análisis de diferentes objetivos : aplicación a la ciudad de México

Scipedia content — Tue, 26 Jan 2021 14:22:55 +0100

El objetivo de la tesis es diseñar un método metaheurístico basado en búsqueda tabú para resolver el problema del transporte BRT en el Distrito Federal con dos objetivos. Se propone aplicar técnicas metaheurísticas a problemas de optimización reales en el sector transporte. El problema de optimización en la operación del BRT es biobjetivo: reducción del tiempo total de viaje y del número de trasbordos, que no son comparables. Se diseñaron, implementaron y analizaron: algoritmo constructivo, procedimiento búsqueda local, procedimiento búsqueda tabú y procedimiento multiarranque (combina algoritmo constructivo con procedimiento de búsqueda tabú (MultiStartTabu)). Se creó un método específico para este problema, siguiendo la estrategia MOAMP para problemas multiobjetivo. Se compararon los resultados obtenidos por el algoritmo diseñado para resolver el problema con los obtenidos por una adaptación del NSGA II. MOAMP obtuvo curvas de eficiencia con mayor número de soluciones, que además dominan a las soluciones obtenidas con NSGA II.

Trajetória tecnológica do veículo elétrico : atores, políticas e esforços tecnológicos no Brasil

Scipedia content — Tue, 26 Jan 2021 14:19:53 +0100

Orientador: Flávia Luciane Consoni de Mello Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Geociências Made available in DSpace on 2018-08-27T17:31:56Z (GMT). No. of bitstreams: 1 Barassa_Edgar_M.pdf: 1763490 bytes, checksum: 150d4a1e9b699993d6ea840d34588afa (MD5) Previous issue date: 2015 Resumo: A indústria automobilística global está passando por um período de reestruturação, a qual deverá contemplar o uso de tecnologias alternativas às tradicionais com o propósito de aumentar a eficiência energética dos veículos e paralelamente reduzir as emissões de poluentes. Neste contexto, os veículos elétricos (VE) caracterizam-se como uma das alternativas possíveis frente a este cenário de novas demandas. Essa dissertação avança nesta temática ao investigar, descrever e analisar a trajetória histórica, tecnológica e de mercado do veículo elétrico. Para o aprofundamento ao tema, observou-se a competição tecnológica pelo sistema de propulsão dominante, que ocorreu entre: 1) o motor a vapor; 2) os conversores eletromecânicos de energia (motores elétricos); e 3) os motores a combustão interna, sendo o último caracterizado como vencedor. Ao longo dos 50 anos que seguiriam a partir do fechamento do motor a combustão interna em 1920 como paradigma tecnológico, os veículos elétricos praticamente desaparecem. O projeto do veículo elétrico só foi retomado a partir da década de 1970, com os estímulos vindos da agenda ambiental, da poluição do ar e seus impactos na saúde pública e do aumento do uso dos combustíveis fósseis. Porém, será a partir do século XXI que o segmento dos veículos elétricos irá ascender tanto do lado tecnológico quanto de mercado. Foram observadas três configurações mais promissoras a respeito da tecnologia dos veículos elétricos: a bateria, híbrido e a células a combustíveis. As três configurações apresentam barreiras e desafios, os quais estão sendo sistematicamente trabalhados pelas empresas que estão dispensando esforços para o segmento. Isto é observado com base na evolução das patentes publicadas sobre veículos elétricos e suas tecnologias. Sendo assim, é possível, ainda, constatar a evolução das vendas dos veículos elétricos nos Estados Unidos, Japão e em um pequeno número de países europeus. O êxito mercadológico fica para os modelos híbridos, com vendas sete vezes superiores aos veículos elétricos a bateria. Transpondo esta discussão para o contexto brasileiro atual, salientamos que o Brasil possui os atores (órgãos governamentais, empresas e instituições públicas de pesquisa) e condições (mercado automobilístico consolidado e know-how) necessários para a formação de um complexo automobilístico voltado aos veículos elétricos, porém as ações em curso no país são pontuais. Ainda que tais iniciativas possam favorecer a criação de competências específicas para o veículo elétrico, elas se mostram pouco efetivas para criar as condições que permitam o Brasil ocupar posição de destaque neste mercado. Ao menos que se projete um rol de políticas claras de apoio e suporte ao desenvolvimento de tecnologias locais destinadas ao veículo elétrico, poucos avanços serão conquistados neste campo tecnológico Abstract: Automobile industry across the world is undergoing structural change. Advances in emission regulations and the effects of oil price fluctuations are forcing carmakers towards new product programs that use new technologies in order to increase the energy efficiency of vehicles, reduce emissions and decrease environment impacts. In this context, electric vehicles have been considered as one of the possible alternatives for this scenario of new demands. This dissertation advances on this topic to investigate, describe and analyze the historical and technological trajectories and market behavior of the electric vehicle. It was observed a technological competition by dominant propulsion system, that had occurred among: 1) the steam engine; 2) electromechanical energy converters (electric motors); and 3) internal combustion engines, the last being characterized as the most used. Throughout the following 50 years from the engine closure based on the internal combustion in 1920, electric vehicles practically disappeared. The electric vehicle project was only resumed after the 1970s, due to the environmental agenda, the air pollution and its impacts on public health and the increase of fossil fuels prices. However, in the 21st century, the segment of electric vehicles has ascended in both technological and market fields. Therefore, it is possible to identify the three most promising settings about electric vehicle technology: battery electric vehicle, hybrid vehicle and fuel cells vehicle. The three configurations have obstacles and challenges, which are being systematically tackled by companies that are dispensing efforts for the segment, based on the evolution of patents published concerning the electric vehicles and their technologies. Thus, it is possible to verify the evolution of the electric vehicles selling in the United States, Japan and a few European countries. The world market success is related to hybrids models, selling seven times more than the battery electric vehicle. In the current Brazilian context, the country has the government agencies, companies and public research intuitions and had the conditions (mature automobile market and know-how) for the formation of an automobile complex of electric vehicles, with off actions. Although such initiatives may favor the creation of specific competencies for electric vehicle, they show little effective to create conditions for the Brazil occupy a prominent position in this market. It should be projected a list clear policies to support the development of local technologies for the electric vehicle, or few advances will be achieved in this technological field Mestrado Politica Cientifica e Tecnologica Mestre em Política Científica e Tecnológic

Modeling Shared-use Urban Mobility Systems to Increase System Performance

Scipedia content — Tue, 26 Jan 2021 14:17:21 +0100

Shared-use mobility systems, which enable users to have short-term access to transportation modes on an on-demand basis, have experienced tremendous growth over the last decade. However, most of the existing systems suffer from two confounding issues: the lack of modeling tools to understand, simulate and predict their behavior and the lack of integration with the existing transit network. To address those issues, this dissertation focuses on investigating the operational challenges of bikesharing systems, with an emphasis on the rebalancing operations and the modeling of a new mobility concept, Car2work, which builds upon existing carsharing ideas and successfully integrates with existing transit networks. A methodological framework to solve the bikesharing rebalancing problem is proposed. The novelties of the approach are that it is proactive instead of reactive, as the bike redistribution occurs before inefficiencies are observed, and uses the outputs of a demand-forecasting technique to decompose the inventory and the routing problem. The decomposition makes the problem scalable, responsive to operator inputs, and able to accommodate user-specific models. Simulation results based on data from the Hubway bikesharing system show that system performance improvements of 7% in the afternoon peak could be achieved.Car2work main goal is to connect commuters with workplaces while leveraging the line-haul capabilities of existing public transit systems and guaranteeing a trip back home, efficiently tackling the “last mile” problem that is a limiting characteristic of public transit. It differs from the traditional dynamic-ridesharing approaches because it is designed for recurrent commuting trips where commuters announce their (multiple) trips in advanced and an automated all-or-nothing matching strategy is performed, guaranteeing a ride home. The problem is formulated as a pure binary problem that is solved using an aggregation/disaggregation algorithm that renders optimal solutions. The solution approach is based on decomposing the problem into a master problem and a sub-problem, reducing the number of decision variables and constraints. As a result, various instances of the problem can be solved in reasonable amount of time, even when considering the transit network. The model can be used to simulate a widespread implementation of the concept.

Extension of a multi-agent transport simulation for traffic signal control and air transport systems

Scipedia content — Tue, 26 Jan 2021 14:14:28 +0100

Die vorliegende Arbeit widmet sich der simulationsbasierten Verkehrsplanung anhand eines Multi-Agenten-Ansatzes. Verkehrsplanerische Maßnahmen, wie Rück- oder Neubau von Infrastruktur, Änderungen in Fahrplänen, Maut oder Geschwindigkeitsbegrenzungen, können anhand der verwendeten Simulation (MATSim, www.matsim.org) mit einer hohen Detailgenauigkeit untersucht werden. Der Fokus liegt auf dem Verkehrsteilnehmer, der sich in der Simulation mikroskopisch durch das Verkehrssystem bewegt und in einem iterativen Prozess dessen Rahmenbedingungen lernt. Die Arbeit behandelt die Themen Lichtsignalanlagensteuerung, Luftverkehr und Softwareentwicklung. Die Arbeit zeigt, wie Lichtsignalanlagen (LSA) in der Simulation abgebildet werden können. Der Verkehrsfluss wird durch ein sehr effizient zu berechnendes „Queue Model“ (Gawron, 1998b;Simon et al., 1999; Cetin, 2005) abgebildet. Anhand einer Erweiterung des „Queue Model's“ können die Effekte von LSA abgebildet werden. Ein entwickeltes Software-Modul modelliert mikroskopische LSA. Durch die Interaktion dieses Moduls mit dem Verkehrsflussmodell können Reaktionen der Nutzer auf eine Änderung der LSA-Steuerung netzwerkweit simuliert werden. Die Resultate zeigen, dass die modellierten Wahlmöglichkeiten der Reisenden, wie z.B. Abfahrtszeit- oder Routenwahl, die Evaluation von LSA-Steuerungen beeinflussen. Verschiedene Optimierungen der LSA-Steuerung werden evaluiert. Die Optimierung von grünen Wellen hat nur geringen Einfluss auf die Verkehrsmuster. Dahingegen kommt es bei einer verkehrsabhängigen Steuerung zu netzwerkweiten Änderungen der Routen. Die Arbeit zeigt weiterhin, wie der Multi-Agenten-Ansatz zur Abbildung von Luftverkehr eingesetzt werden kann. Dabei wird das Simulationsmodul für öffentlichen Nahverkehr genutzt und entsprechend angepasst. Somit werden Passagiere auf allen Teilen ihrer Reise personenscharf abgebildet. Daraufhin wird die Verkehrsmittelwahl in die Modellierung aufgenommen. Das existierende multinomiale Logit-Modell für die Verkehrsmittelwahl (Rieser et al., 2008, Rieser, 2010) wird durch eine „Path Size Logit“-Formulierung erweitert, die Überlappungen von Routen explizit berücksichtigt. Dies behebt Artefakte des Sampling-Prozesses und ermöglicht somit die Analyse von Wettbewerbsmärkten zwischen Verkehrsträgern, z.B. zwischen Hochgeschwindigkeitszügen und Flugverbindungen. Die Software-Architektur der Simulation war anfangs monolytisch aufgebaut, funktionell schwer zu erweitern und schien für weitere Forschungszwecke nicht geeignet. In der Arbeit wird das Redesign auf eine modulare, erweiterbare Architektur erläutert. Diese soll es Forschern erlauben eigene Softwarekomponenten als Erweiterung bereitzustellen. Wie am Beispiel des Moduls für LSA gezeigt wird, ist dies möglich, sofern geeignete Schnittstellen zur Verfügung gestellt werden. Das Modul ist vom eigentlichen Simulationsprozess weitgehend abgekoppelt und kann in Teilen oder komplett ersetzt werden. This thesis aims at the simulation based assessment of transport planning using a multi-agent simulation approach. Effects of transport policies like (de-)construction of infrastructure, changes in timetable, or regulations like speed limits or tolls can be analyzed with a high level of detail by the simulation under consideration (MATSim, see www.matsim.org). Travelers are represented as individual entities that make their journey through the transport system and learn iteratively the modeled constraints. The thesis covers three areas: Traffic signal control, air transport systems, and software engineering. It is shown how traffic signal control can be simulated with the multi-agent approach. Traffic flow is simulated by a computationally efficient queue model (Gawron, 1998b;Simon et al., 1999; Cetin, 2005). In this work, the queue model is extended to capture effects of traffic signals. A software component for microscopic modeling of traffic signals is developed. This component interacts with the traffic flow model and allows the simulation of network wide effects that result from a change of traffic signal control. Results indicate that the available choice dimensions of travelers, such as route choice or departure time choice, influence the evaluation of traffic signal control. The approach is applied to test different optimizations of traffic signal control. The optimization of offsets for coordination of adjacent junctions (green waves) has little impact on the network wide traffic patterns. In contrast, a traffic-actuated signal control results in network wide changes of travelers' route choice. The thesis also shows how the multi-agent approach is applied to air transport systems. The approach uses the public transport functionality of the simulation and modifies it for air transport. As a result, individual passengers are included into the modeling on all stages of their trip. Then, mode choice between air and alternative transport modes is added. The existing Multinomial Logit model for mode choice (Rieser et al., 2008, Rieser, 2010) is enriched by a Path Size Logit formulation that takes path overlap into account. This removes artefacts of the sampling process and enables the analysis of competitive markets, e.g., between high speed rail and air transport. The software architecture of the simulation was initially a monolithic piece of software, difficult to customize, and appeared not suited for further research. The thesis discusses the redesign of the software. Design goals aim at a modular, extensible architecture that permits researchers to modify or add certain components to the overall simulation under the assumption that suitable interfaces are available. As proof of concept, the module for fixed-time traffic signal control is provided as extension. The module is decoupled from the overall simulation approach and can be replaced in part, or completely.

Evaluation of the electric vehicles impact on the distribution systems of the EDP Bandeirante and EDP ESCELSA utilities.

Scipedia content — Tue, 26 Jan 2021 14:12:11 +0100

O objetivo deste trabalho é avaliar qual seria o impacto da inserção dos veículos elétricos nos sistemas de distribuição de energia elétrica de duas distribuidoras brasileiras, a EDP Bandeirante e EDP ESCELSA. Como esta tecnologia ainda não se encontra em utilização no Brasil, será adotada uma abordagem prospectiva, de modo a projetar o crescimento da frota de veículos elétricos até o ano de 2020. Para que se possa simular em uma sub estação, qual será o impacto da adoção desta tecnologia. Utilizando-se das projeções de crescimento da frota, também serão quantificados o impacto na matriz energética nacional e nas emissões de gases do efeito estufa. This work, aims to evaluate the impact of the electric vehicles insertion on two power distribution utilities, EDP Bandeirante and EDP ESCELSA. How the electric vehicles aren´t a reality on Brazil, an prospective approach will be adopted, to project the growth of the electric vehicles fleet until the 2020 year, so that can be simulated in one substation, the impact that would be caused by the adoption of this technology. Using these projections, the impact on Brazilian energetic matrix, and the greenhouse gas emissions will be calculated to.

Design and Management of Networked Energy and Logistics Systems

Scipedia content — Tue, 26 Jan 2021 14:11:47 +0100

Key to a sustainable future is the transformative human use of energy and transportation--from a fossil-fuel dominant to a renewables-mixed portfolio of energy production, from a supply-follow-demand to a demand-responsive pattern of power consumption, and from capacity-oriented to usage-based allocation of logistics mobility. Motivated by these trends, my dissertation presents three essays to address the challenges that governments and businesses worldwide face in, respectively, 1) planning infrastructure for wind energy production, 2) designing coordination strategies for large-scale charging of plug-in electric vehicles, and 3) evaluating the economic and environmental viability of using shared mobility for retail e-commerce. Two common threads underlying my dissertation research are 1) strategic decision-making with insights into the operational level and 2) network optimization that takes into account the interdependencies both within and out of system boundaries. Solving these network optimization problems invokes the techniques of mixed-integer conic programming, decomposition algorithms, and continuous approximation modeling. Specifically, the three essays are organized as three chapters of the dissertation:Chapter 1 studies the problem of jointly planning energy storage (ES) and transmission for wind energy generation. Regions with abundant wind resources usually have no ready access to the existing electric grid. However, building transmission lines that instantaneously deliver all geographically distributed wind energy can be costly. Energy storage systems can help reduce the cost of bridging wind farms and grids, and can mitigate the intermittency of wind outputs. We propose models of transmission network planning with colocation of ES systems. Our models determine the sizes and sites of ES systems as well as the associated topology and capacity of the transmission network under the feed-in-tariff policy instrument. We first formulate a location model as a mixed-integer second-order-conic program to solve for the ES-transmission network design with uncapacitated storage. Then we propose a method to choose ES sizes by deriving a closed-form upper bound. The major insight is that, in most cases, using even small-sized ES systems can significantly reduce the total expected cost, but their marginal values diminish faster than those of the transmission lines as their capacities expand. Despite uncertainties in climate, technologies, and construction costs, the cost-efficient infrastructure layout is remarkably robust. We also identify the major bottleneck cost factors for different forms of ES technologies.Chapter 2 presents a hierarchical optimal control framework to coordinate the charging of plug-in electric vehicles in multifamily dwellings. A particular scenario is considered where distributed urban residential communities access electric power supplies through a common primary distribution transformer. We first formulate a centralized finite-horizon control problem. The proposed multistage mixed integer program seeks to maximize the total utility of the charging service provider while satisfying customers' charge demands and transformer capacity constraints. By exploiting the structure of the centralized model, we decompose the centralized problem with respect to each parking deck, based on the Lagrangian relaxation method; we design an effective heuristic method to find feasible solutions to speed up convergence. Case studies on operations of five parking decks following different charging strategies are carried out. Simulation results demonstrate that the proposed distributed hierarchical charging strategy outperforms the centralized charging strategy from the perspective of computational requirements. System reliability and customer privacy protection are also discussed.Chapter 3 studies an integrated logistics system with shared mobility for retail e-commerce. Two socioeconomic transformations, namely, the booms in sharing economy and retail e-commerce, lead to the prospect where shared mobility of passenger cars prevails throughout urban areas for home delivery services. Local governments and logistics services providers are in need of evaluating the potentially substantial impacts of this mode shift, given their societal and environmental concerns and economic objectives. We addresses this need by providing a logistics planning framework: 1) Part one presents logistics planning models. These models characterize optimal routes of short-haul trucks and passenger cars, and generate the optimal density of service zones within which passenger vehicles pick up goods and fulfill the last-mile delivery. 2) Part two, based on empirical estimates, analyzes operating costs and greenhouse gas emissions implications of this sharing logistics paradigm. The findings suggest that a transition to this paradigm has the potential for creating considerable economic and environmental benefits, although immediate savings are not as achievable as one may conjecture. If being in this paradigm, even exclusively minimizing operating costs does not significantly increase emissions relative to the minimum level of emissions. A non-linear payment scheme can be used to efficiently induce shared mobility into passenger car home delivery services.

Use of high-speed rail services by business travellers

Scipedia content — Tue, 26 Jan 2021 14:10:40 +0100

Data-Driven Methods for Improved Estimation and Control of an Urban Arterial Traffic Network

Scipedia content — Tue, 26 Jan 2021 14:09:03 +0100

Transportation is a field which is universal in our society: people from every country, culture or background are familiar with the challenges of getting around in our built environment. Yet what is not always so obvious to the average traveler is how the techniques and tools of designing, observing, and controlling our modern transportation networks are derived. In fact, the theory of traffic engineering has many gaps and unknowns that are the topic of ongoing research efforts in the academic community. This work presents a collection of theoretical and practical methodologies to advance the study of traffic flow modeling, state estimation, and control of signalized roadways in particular. It uses theory from traditional transportation engineering, but also demonstrates the application of new tools from control theory and computer science to the specific application of signalized traffic networks. First, two numerical modeling dynamics representing traffic flows on signalized arterials are presented: the well-known Cell Transmission Model, a discretization of the physical hydrodynamic laws believed to govern vehicle flows, and a new Vertical Cell Model which resembles classical "store-and-forward" models with the addition of transit delays and finite buffer capacities. Each of these models is implemented in a common software framework, which provides an ideal experimental platform for direct comparison of the competing dynamics. A chapter in this dissertation contributes a validation and comparison of the two models against real vehicle trajectory data on an existing signalized road network. Accuracy and confidence in such traffic models requires complimentary methods of observing true traffic conditions to provide initial conditions and real-time state estimates. Yet there are many technological deficiencies in existing urban roadway detection systems that prevent the acquisition of a real-time estimate of arterial link state (or queue length) at signalized intersections. Hence this thesis also contains methodology to improve the estimates obtained from existing hardware by combining data from typical infrastructure sensors with new sources of Lagrangian probe measurements. These are then assimilated into a detailed model of flow dynamics. This technique was previously proposed for continuous-flow (freeway) networks, but required novel adaptions to be applied to an interrupted-flow setting. This dissertation next explores advancements in theoretically optimal control algorithms for statistically-modeled signalized queueing networks. In the context of a large body of previous work on flow-impeding control for vertical queueing networks, the practical challenges of traffic signal control are highlighted. Some of these challenges are tackled in the specific case of the max pressure controller, an algorithm derived from the field of communications networks that has been shown to optimize through-flow in an idealized network model.The lack of adequate measurements or demand-volume data has historically been a major limitation in advancing research on signalized arterial road networks. Yet the current revolution of inexpensive storage and processing of "big data" shows promise for improving daily operations of existing roadways without the need for expensive new hardware systems. One example of this potential appears is the case of traffic signal control. Existing traffic signals are capable of operating more efficiently by changing signal plans based on real-time demand measurements through a traffic responsive plan selection (TRPS) mode of operation (rather than depending on a rigid schedule for plan changes). However, this mode is rarely used in practice because its calibration process is not accessible or intuitive to traffic technicians. This dissertation presents an application of statistical learning techniques to improve the process of calibrating and implementing an existing TRPS mechanism. A proof-of-concept implementation using historical sensor data from a busy urban intersection demonstrates that real operational improvements may be immediately achievable using existing sensing infrastructure.

En studie om diffusion av batteridrivna elektriska fordon med hänsyn till påverkan av teknisk utveckling : En modellbaserad studie av den svenska marknaden

Scipedia content — Tue, 26 Jan 2021 14:06:05 +0100

Battery Electric Vehicle as an environmental friendly transportation alternative has already emerged as well as fade out of the market twice. It has been reintroduced along with the increasing concern about the environment issue. This recent diffusion is surrounded by lots of dynamic changes and uncertainties. However, most current studies focus on political, financial as well as infrastructure factors but neglect factors like the technology especially how people perceived it. Therefore, this study mainly research into how the technology development impact on the diffusion of battery electric vehicle.To achieve this aim, a model based study was conducted targeting Swedish electric vehicle market. In the research, customers are considered to be the target objective because they are the one who perceive the technology and make decision for adoption directly. In order to know the relationship between them, researches have been conducted through qualitative and quantitative approach. Empirical work including interviews and survey were conducted through tripartite aspect to investigate the customer needs and related technology. The investigation indicates the environmentally friendly performance is the key driving force perceived by the early adopters. Meanwhile, range issue, total cost of ownership and safety & technology reliability are identified as the top three critical concerns that hold back customer purchasing decision. A modified classic model for the innovation diffusion has been proposed which is used to evaluate the technology’s perception based on historical data. Two BEV- related technologies were chosen as examples to prove and illustrate the relationship between technology development and electric vehicle diffusion.The results showed that the BEV-related technologies, which have potential ability to address critical customer demand, are able to impact on the customer adoption positively through valid perception by customer. Taking technology development and perception into consideration, the diffusion process should be accelerated to some extent. Technologies which can be more easily perceived tend to have more impact in the diffusion process. Batteridrivna elektriska fordon(BEV) som ett miljövänligt transportalternativ redan har dykt upp, liksom försvunnit från marknaden två gånger. Det har återinförts tillsammans med den ökande oron för miljöfrågan. Denna nya diffusion är omgiven av dynamiska förändringar och osäkerheter. Men de flesta av dagens studier fokuserar på politiska, ekonomiska och infrastrukturella faktorer, men försummar faktorer relaterat till tekniken framför allt hur människor uppfattar det. Därför undersökte denna studie främst hur den tekniska utvecklingen påverkar spridningen av batteridrivna fordon.För att uppnå detta syfte, gjordes en modell baserad kring en studie av den svenska elbilsmarknaden. I forskningen anses kunderna vara målet målgruppen eftersom de är de som uppfattar tekniken och tar beslut om införandet direkt. För att veta förhållandet mellan dem, har kvalitativa och kvantitativa undersökningar genomförts. Empiriskt arbete inklusive intervjuer och undersökningen genomfördes genom tre olika aspekter för att undersöka kundernas behov och relaterad teknik. Undersökningen visar att miljövänlig prestanda är den viktigaste drivkraften som uppfattas av early adopters. Samtidigt har räckviddsproblematiken, totala ägandekostnaden och tillförlitlighet i säkerhet och teknologi identifierats som de tre kritiska problemen som tillbakahåller kunden från ett köpbeslut. En modifierad klassisk modell för innovationsspridning har föreslagits som används för att utvärdera teknikens uppfattning baserad på historiska data. Två BEV-relaterade teknologier valdes som exempel för att bevisa och illustrera förhållandet mellan teknikutveckling och elbilsdiffusion.Resultaten visade att BEV-relaterad teknologi, som har potential förmåga att ta itu med den kritiska efterfrågan från kunderna, kan påverka kundacceptans positivt genom giltig uppfattning av kunden. Om teknikutveckling och uppfattning beaktas, bör diffusionsprocessen påskyndas i viss utsträckning. Teknik som lättare kan uppfattas tenderar att ha mer genomslag i diffusionsprocessen.

Avrupa Hava Trafiği Ve Uzay-zamansal Grid Salınım Modellemede Veri Analizi Ve Simulasyonu Uygalamaları

Scipedia content — Tue, 26 Jan 2021 14:04:17 +0100

Tez (Yüksek Lisans) -- İstanbul Teknik Üniversitesi, Fen Bilimleri Enstitüsü, 2015

Διερεύνηση των σχέσεων ανταγωνισμού και συμπληρωματικότητας της αεροπορικής και ακτοπλοϊκής εξυπηρέτησης στον ελληνικό χώρο

Scipedia content — Tue, 26 Jan 2021 14:02:04 +0100

Contributions to multilevel splitting for rare events, and applications to air traffic

Scipedia content — Tue, 26 Jan 2021 14:00:25 +0100

The thesis deals with the design and mathematical analysis of reliable and accurate Monte Carlo methods in order to estimate the (very small) probability that a Markov process reaches a critical region of the state space before a deterministic final time. The underlying idea behind the multilevel splitting methods studied here is to design an embedded sequence of intermediate more and more critical regions, in such a way that reaching an intermediate region, given that the previous intermediate region has already been reached, is not so rare. In practice, trajectories are propagated, selected and replicated as soon as the next intermediate region is reached, and it is easy to accurately estimate the transition probability between two successive intermediate regions. The bias due to time discretization of the Markov process trajectories is corrected using perturbed intermediate regions as proposed by Gobet and Menozzi. An adaptive version would consist in the automatic design of the intermediate regions, using empirical quantiles. However, it is often difficult if not impossible to remember where (in which state) and when (at which time instant) did each successful trajectory reach the empirically defined intermediate region. The contribution of the thesis consists in using a first population of pilot trajectories to define the next threshold, in using a second population of trajectories to estimate the probability of exceeding this empirically defined threshold, and in iterating these two steps (definition of the next threshold, and evaluation of the transition probability) until the critical region is reached. The convergence of this adaptive two-step algorithm is studied in the asymptotic framework of a large number of trajectories. Ideally, the intermediate regions should be defined in terms of the spatial and temporal variables jointly (for example, as the set of states and times for which a scalar function of the state exceeds a time-dependent threshold). The alternate point of view proposed in the thesis is to keep intermediate regions as simple as possible, defined in terms of the spatial variable only, and to make sure that trajectories that manage to exceed a threshold at an early time instant are more replicated than trajectories that exceed the same threshold at a later time instant. The resulting algorithm combines importance sampling and multilevel splitting. Its preformance is evaluated in the asymptotic framework of a large number of trajectories, and in particular a central limit theorem is obtained for the relative approximation error.; La thèse porte sur la conception et l'analyse mathématique de méthodes de Monte Carlo fiables et précises pour l'estimation de la (très petite) probabilité qu'un processus de Markov atteigne une région critique de l'espace d'état avant un instant final déterministe. L'idée sous-jacente aux méthodes de branchement multi-niveaux étudiées ici est de mettre en place une suite emboitée de régions intermédiaires de plus en plus critiques, de telle sorte qu'atteindre une région intermédiaire donnée sachant que la région intermédiaire précédente a déjà été atteinte, n'est pas si rare. En pratique, les trajectoires sont propagées, sélectionnées et répliquées dès que la région intermédiaire suivante est atteinte, et il est facile d'estimer avec précision la probabilité de transition entre deux régions intermédiaires successives. Le biais dû à la discrétisation temporelle des trajectoires du processus de Markov est corrigé en utilisant des régions intermédiaires perturbées, comme proposé par Gobet et Menozzi. Une version adaptative consiste à définir automatiquement les régions intermédiaires, à l’aide de quantiles empiriques. Néanmoins, une fois que le seuil a été fixé, il est souvent difficile voire impossible de se rappeler où (dans quel état) et quand (à quel instant) les trajectoires ont dépassé ce seuil pour la première fois, le cas échéant. La contribution de la thèse consiste à utiliser une première population de trajectoires pilotes pour définir le prochain seuil, à utiliser une deuxième population de trajectoires pour estimer la probabilité de dépassement du seuil ainsi fixé, et à itérer ces deux étapes (définition du prochain seuil, et évaluation de la probabilité de transition) jusqu'à ce que la région critique soit finalement atteinte. La convergence de cet algorithme adaptatif à deux étapes est analysée dans le cadre asymptotique d'un grand nombre de trajectoires. Idéalement, les régions intermédiaires doivent êtres définies en terme des variables spatiale et temporelle conjointement (par exemple, comme l'ensemble des états et des temps pour lesquels une fonction scalaire de l’état dépasse un niveau intermédiaire dépendant du temps). Le point de vue alternatif proposé dans la thèse est de conserver des régions intermédiaires simples, définies en terme de la variable spatiale seulement, et de faire en sorte que les trajectoires qui dépassent un seuil précocement sont davantage répliquées que les trajectoires qui dépassent ce même seuil plus tardivement. L'algorithme résultant combine les points de vue de l'échantillonnage pondéré et du branchement multi-niveaux. Sa performance est évaluée dans le cadre asymptotique d'un grand nombre de trajectoires, et en particulier un théorème central limite est obtenu pour l'erreur d'approximation relative.

An Agent-Based Approach to Improving Commuter Traffic by Means of Advanced Traveler Information Systems

Scipedia content — Tue, 26 Jan 2021 14:00:03 +0100

Extensive urban and metropolitan development over the past decades has resulted in the need to better move goods and people over the nation's motorways. However, physical limitations in motorway infrastructure and inefficient use of existing infrastructure have caused considerable economic loss through the late delivery of goods and loss of productive labor, as well as environmental damage, national security concerns, and financial burden resulting from fuel wasted during congestion. Improving utilization of existing physical assets is a crucial and relatively inexpensive means to achieving those ends. The proliferation of inexpensive mobile devices over the past decade has fundamentally changed traffic management, both from the perspective of motorists, as well as planners and logisticians. Motorists now have rapid access to realtime traffic information, and can thus easily re-plan their journeys while already underway. Likewise, organizations that operate these services have access to motorists' whereabouts and itineraries, and are in a position to shape and manage traffic by providing instructions to individual drivers. This research addresses an exploratory agent-based approach towards modeling a road network in which agents 1. have varied routing behaviors and 2. may or may not have access to realtime rerouting capabilities. The objective is to explore what effect modifying driver portfolios will have on the ``price of anarchy" associated with a commuter network. This information can be used by urban planners to determine which driver and information-access portfolios result in the least vehicle delay and best use of motorway resources, thus informing policies and incentives that can alleviate network congestion. Results on a Northern Virginia test case demonstrate that active rerouting has overall modestly positive effects on network latency for small and moderately-sized populations; however, in larger populations, active rerouting can lead to competitive pressures between agents, resulting in overall degradation of performance. It is suggested that future work implement competing managerial agent classes, as well as test over additional geospatial datasets.

Cognitive Surveillance Architecture for Scenario Understanding

Scipedia content — Tue, 26 Jan 2021 13:58:56 +0100

Uno de los mayores retos para la comunidad científica es conseguir que las máquinas posean en un futuro la capacidad del sistema visual y cognitivo humanos, de forma que, por ejemplo, en entornos de video vigilancia, puedan llegar a proporcionar de manera automática una descripción fiable de lo que está ocurriendo en la escena. En la presente tesis, mediante la propuesta de un marco de trabajo de referencia, se discuten y plantean los pasos necesarios para el desarrollo de sistemas más inteligentes capaces de extraer y analizar, a diferentes niveles de abstracción y mediante distintos módulos de procesamiento independientes, la información necesaria para comprender qué está sucediendo en un conjunto amplio de escenarios de distinta naturaleza. Se parte de un análisis de requisitos y se identifican los retos para este tipo de sistemas en la actualidad, lo que constituye en sí mismo los objetivos de esta tesis, contribuyendo así a un modelo de datos basado en el conocimiento que permitirá analizar distintas situaciones en las que personas y vehículos son los actores principales, dejando no obstante la puerta abierta a la adaptación a otros dominios. Así mismo, se estudian los distintos procesos que se pueden lanzar a nivel interno así como la necesidad de integrar mecanismos de realimentación a distintos niveles que permitan al sistema adaptarse mejor a cambios en el entorno. Como resultado, se propone un marco de referencia jerárquico que integra las capacidades de percepción, interpretación y aprendizaje para superar los retos identificados en este ámbito; y así poder desarrollar sistemas de vigilancia más robustos, flexibles e inteligentes, capaces de operar en una variedad de entornos. Resultados experimentales ejecutados sobre distintas muestras de datos (secuencias de vídeo principalmente) demuestran la efectividad del marco de trabajo propuesto respecto a otros propuestos en el pasado. Un primer caso de estudio, permite demostrar la creación de un sistema de monitorización de entornos de parking en exteriores para la detección de vehículos y el análisis de plazas libres de aparcamiento. Un segundo caso de estudio, permite demostrar la flexibilidad del marco de referencia propuesto para adaptarse a los requisitos de un entorno de vigilancia completamente distinto, como es un hogar inteligente donde el análisis automático de actividades de la vida cotidiana centra la atención del estudio. ABSTRACT One of the most ambitious objectives for the Computer Vision and Pattern Recognition research community is that machines can achieve similar capacities to the human's visual and cognitive system, and thus provide a trustworthy description of what is happening in the scene under surveillance. Thus, a number of well-established scenario understanding architectural frameworks to develop applications working on a variety of environments can be found in the literature. In this Thesis, a highly descriptive methodology for the development of scene understanding applications is presented. It consists of a set of formal guidelines to let machines extract and analyse, at different levels of abstraction and by means of independent processing modules that interact with each other, the necessary information to understand a broad set of different real World surveillance scenarios. Taking into account the challenges that working at both low and high levels offer, we contribute with a highly descriptive knowledge-based data model for the analysis of different situations in which people and vehicles are the main actors, leaving the door open for the development of interesting applications in diverse smart domains. Recommendations to let systems achieve high-level behaviour understanding will be also provided. Furthermore, feedback mechanisms are proposed to be integrated in order to let any system to understand better the environment and the logical context around, reducing thus the uncertainty and noise, and increasing its robustness and precision in front of low-level or high-level errors. As a result, a hierarchical cognitive architecture of reference which integrates the necessary perception, interpretation, attention and learning capabilities to overcome main challenges identified in this area of research is proposed; thus allowing to develop more robust, flexible and smart surveillance systems to cope with the different requirements of a variety of environments. Once crucial issues that should be treated explicitly in the design of this kind of systems have been formulated and discussed, experimental results shows the effectiveness of the proposed framework compared with other proposed in the past. Two case studies were implemented to test the capabilities of the framework. The first case study presents how the proposed framework can be used to create intelligent parking monitoring systems. The second case study demonstrates the flexibility of the system to cope with the requirements of a completely different environment, a smart home where activities of daily living are performed. Finally, general conclusions and future work lines to further enhancing the capabilities of the proposed framework are presented.

Demiryolu Traverslerinin Çok Yönlü İncelenmesi Ve Örnek Hat Üzerinde Kullanılan Farklı Tipteki Traverslerin İrdelenmesi

Scipedia content — Tue, 26 Jan 2021 13:56:59 +0100

Tez (Yüksek Lisans) -- İstanbul Teknik Üniversitesi, Fen Bilimleri Enstitüsü, 2015

Yol Taşıtları İçin İleri Kontrol Sistemleri

Scipedia content — Tue, 26 Jan 2021 13:54:49 +0100

Tez (Doktora) -- İstanbul Teknik Üniversitesi, Fen Bilimleri Enstitüsü, 2015

Heuristic Solutions for Electric Vehicle Routing Problem with Time Windows and Recharging Stations

Scipedia content — Tue, 26 Jan 2021 13:52:34 +0100

Due to the regulation and laws concerning the emission of greenhouse gasses, carriers are starting to use electric vehicles for last-mile deliveries. The limited battery capacities of these vehicles necessitate visits to recharging stations during delivery tours of industry-typical length, which have to be considered in the route planning to avoid inefficient vehicle routes with long detours. This thesis seeks to propose new heuristic solution methods for Electric Vehicle Routing Problem with Time Windows (E-VRPTW), which incorporates the possibility of recharging at any of the available charging stations to minimize the total travel distance based on the Clarke and Wright (CW) Saving Heuristic. The solution method focuses on the construction of routes according to waiting time of vehicles, determined priority of customers with regard to their earliest starting service time, customers’ demands and etc. Moreover, the recharging rate, vehicle freight capacity, battery capacity, time windows and recharging time are considered to make it close to real-life logistics problems. Numerical tests are performed on newly designed instances by Schneider and performances of proposed methods are discussed. Keywords: Vehicle Routing Problem, Clarke and Wright Saving Heuristic, Green Logistic, Electric Vehicles, Combinatorial Optimization ÖZ : Sera gazlarının salınımı ile ilgili kural ve yasalardan dolayı taşımacılar şehir içi taşımalarını elektrikle çalışan araçlarla yapmaya başlamışlardır. Bu araçların sınırlı olan batarya kapasiteleri, taşıma sırasında zorunlu olarak batarya dolum istasyonlarında şarj edilmeleri gereksinimini doğurmakta ve bu durum da uzun ve verimsiz rotaların önlenmesi için rota planlamasında gözönüne alınmalıdır. Bu tezin amacı, alınan toplam mesafeyi enküçüklemek amacıyla şarjın tüm dolum istasyonlarında mümkün olduğu ve Clarke & Wright tasarruf algoritmasını esas alan Electric Vehicle Routing Problem with Time Windows (E-VRPTW) problemine yeni bir sezgisel çözüm yöntemi önermektir. Önerilen çözüm yöntemi öncelikle araçların bekleme sürelerine, müşterilerin zaman önceliklerine, taleplerine vs. göre rotalar oluşturmaya odaklanmaktadır. Problemin lojistik olarak daha da gerçekçi olmasını sağlamak üzere araçların taşıma kapasiteleri, batarya kapasiteleri, zaman aralıkları, şarj zamanları ve hızları da gözönüne alınmıştır. Schneider’in değerleri üzerinden sayısal deneyler de yapılmış ve önerilen yöntemlerin performansları da tartışılmıştır. Anahtar Kelimeler: Araç rotalama sorunu, Clarke ve Wright tasarruf sezgiseli, yeşil lojistik, elektrikli araçlar, birleşi eniyilemesi Master of Science in Industrial Engineering. Thesis (M.S.)--Eastern Mediterranean University, Faculty of Engineering, Dept. of Industrial Engineering, 2014. Co-Supervisor: Assoc. Prof. Dr. Bülent Çatay, Supervisor: Assist. Prof. Dr. Gökhan İzbırak.

ATC complexity measures: Formulas measuring workload and complexity at Stockholm TMA

Scipedia content — Tue, 26 Jan 2021 13:48:48 +0100

Workload and complexity measures are, as of today, often imprecise and subjective. Currently, two commonly used workload and complexity measuring formulas are Monitor Alert Parameter and the “Bars”, both using the same measurement variables; amount of aircraft and time. This study creates formulas for quantifying ATC complexity. The study is done in an approach environment and is developed and tested on Stockholm TMA by the creation of 20 traffic scenarios. Ten air traffic controllers working in Stockholm TMA studied the complexity of the scenarios individually and ranked the scenarios in reference to each other. Five controllers evaluated scenario A1-A10. These scenarios were used as references when creating the formulas. The other half of the scenarios, B1-B10, ranked by another five controllers, was used as validation scenarios. Factors relevant to an approach environment were identified, and the data from the scenarios were extracted according to the identified factors. Moreover, a regression analysis was made with the ambition to reveal appropriate weights for each variable. At the first regression, called formula #1, some parameter values were identical. Also, some parameter weights became negative in the regression analysis. The basic requirements were not met and consequently, additional regressions were done; eventually forming formula #2. Formula #2 showed stable values and plausible parameter weights. When compared to a workload measuring model of today, formula #2 showed better performance. Despite the small amount of data samples, we were able to prove a genuine relation between three, of each other independent, variables and the traffic complexity.

Modeling of fast dc charger for electric vehicles and integration to grid

Scipedia content — Tue, 26 Jan 2021 13:46:45 +0100

TEZ10412 Tez (Yüksek Lisans) -- Çukurova Üniversitesi, Adana, 2015. Kaynakça (s. 71-74) var. xv, 75 s. : tablo ; 29 cm. Dünya çapındaki endüstriyelleşme enerji tüketiminin giderek artmasına sebep olmuştur. Artan bu tüketim fosil yakıtlar tarafından sağlanmaktadır. Fozil yakıt tüketimi çevre kirliliğine sebep olmaktadır. Buna ek olarak dünya fosil yakıt rezervleri ise az kalmıştır. Dünya genelinde kullanılan içten yanmalı motorlu araçların yakıtları da fosil yakıtlar olup fosil yakıt tüketiminin büyük çoğunluğunu onlar oluşturmaktadır. Bunun yanı sıra elektrikli araçlar gelenekel araçlara gore temiz, sessiz ve kullanımı daha kolaydır. Bu sebeplerde ötürü elektrikli araçlara olan talep artmıştır. Bu tez çalışmasında elektrikli araçlar için şarj edici devre modellemesi yapılarak sisteme entegrasyonu çalışılmıştır. Çalışmada aynı zamanda literatürdeki önemli elektrikli araç şarj edici devre modellemeleri incelenmiş, bunların avantaj ve dezavantajları tartışılmıştır. Bu topolojilerden en yaygın olan sabit akım sabit gerilim modeli çalışmaya uygulanmıştır. Bu topolojinin en büyük avantajı bataryayı en uygun şekilde tamamen doldurabilmektir. Daha sonra bu topoloji ile sistem modellenerek değişik durumlardaki davranışlar incelenmiştir. Sistem simülasyonu için Çukurova Üniversitesinin altyapısı kullanılmıştır. Buna ek olarak, elektrikli araç şarj olurken sistemden çekilen akım ve harmonik değerleri, altyapının yeterli olup olmaması gibi konular araştırılmıştır. Araştırmalar sonucunda altyapının yetersiz olduğuna kanaat getirilirse kurulu sistemin nerelerde yetersiz kaldığı tespit edilip yeni altyapı sistemlerinin nerelerde ihtiyaç duyulacağı belirlenecektir. Çalışmada incelenen örnek olaylarda şarj istasyonu ve sistemin performansları analiz edilmiş olup, aynı zamanda birden çok elektrikli aracın şarj edilmesi durumları incelenmiştir. Energy consumption is increasing gradually with worldwide industrialization. The increase in consumption of energy creates a big amount of demand for production which is supplied by fossil fuels. The consumption of fossil fuels leads to environmental pollution. Additionally, limited petroleum reserves are remained. There is an enormous amount of fossil fuel consumption by internal combustion vehicles that are the most widely used vehicles worldwide. In addition to this, electric vehicles are clean, silent and simple to operate. Because of these reasons, the demand for electric vehicles is increasing. In this thesis, charger circuit for electric vehicles and its integration to grid are studied. In the study, significant charger modeling topologies in the literature are investigated. Advantages and disadvantages of these topologies are discussed. Among these topologies, one of the most common (constant current-constant voltage) topology is used. The best advantage of the studied topology is recharging the battery in the most appropriate manner. Data of Çukurova University’s infrastructure is used for the system. Additionally, in the study we will examine the current drawn by the system, whether the infrastructure is adequate or not. If the results of the examination are found to be inadequate, then we should determine where new infrastructure systems will be needed. Also, the performance of charging station and grid for different cases are analyzed; response of multiple synchronous charging is also investigated.

Evaluating Three Alternative Designs for Reducing Delay at an Intersection in Dohuk, Iraq

Scipedia content — Tue, 26 Jan 2021 13:46:21 +0100

BSTRACT: Traffic delay is one of the most important factors used in intersection analysis. This study focused on the average delay by looking at different alternative junction models. These different models analyzed with and without signalization according to cycle length in order to help create alternate designs. Green intervals were optimized to reduce average delay in order to assist the level of service for the given junction. The traffic and geometric data were taken from the Imam Hamza Intersection as a case study. A delay problem in this intersection of Dohuk city (northern Iraq) was analyzed and redesigned under the present conditions of right-of-way and volumes of traffic. Firstly redesign for signalized intersection was done by expanding the roads of each approach. Then designs of three new interchange models were proposed. A forecasting of traffic volumes for the next fifteen years was taken using each design model. The simulations for these new models were taken by applying different scenarios for each model in order to find the best results of delay and level of service. Likewise a comparison was made based on the best amount of delay obtained from these new models. Finally, the level of delay for the peak hours of each model was compared with the current level of delay in the intersection in order to find the total delay hours for next fifteen years and determine the most effective design in terms of reducing delay in the given intersection. The conclusion of this study displayed the second model diamond interchange had the minimum results of delay comparing with the other models. Keywords: Delay, Signalized intersection, Diamond interchange, Imam Hamza Intersection, Level of service, Traffic jam, Delay time cost. ………………………………………………………………………………………………………………………… ÖZ: Kavşak analizinde en önemli etkenlerden biri de trafikte yaşanan gecikmelerdir. Bu araştırma alternatif kavşak modellerini ele alarak ortalama bekleme sürelerinin sonuçlarını mercek altına almayı hedeflemektedir. Bu farklı modeller alternatif tasarımlar yaratmak için sinyal süresine göre hem sinyalizasyon ile hem de sinyalizasyonsuz halde analiz edilecektir. Söz konusu olan kavşağın hizmet seviyesini artırmak için yeşil ışığın süreleri en iyi şekilde kullanılarak ortalama bekleme gecikme süresinin azaltılması amaçlanmaktadır. Trafik ve geometrik veriler örnek olay incelemesi olarak Imam Hamza kavşağından alınacaktır. Irak’ın kuzeyindeki Dohuk şehrinde bulunan bu kavşaktaki bir gecikme problemi mevcut trafiğin sağ şeridi ve trafik yoğunluğunun durumu göz önünde bulundurularak analiz edilip yeniden tasarlanacaktır. Elmas şeklinde köprülü kavşağın üç yeni modelini tasarlamak için önümüzdeki 15 yılın trafik yoğunluk tahminleri dikkate alınacaktır. Aynı şekilde söz konusu olan yeni modeller ile benzer yollardaki gecikme süresi baz alınarak bir karşılaştırma da yapılacaktır. Bu süre miktarı tespit edilince gecikmeden dolayı oluşan maliyet belirlenebilecektir. Son olarak, gelecek 15 yılın toplam gecikme süresini bulmak, en etkili modeli belirlemek ve verilen kavşaktaki gecikme süresini düşürmek için her modelin yoğun saatlerdeki gecikme süresi ve kavşaktaki şimdiki gecikme süresi karşılaştırıldı. Anahtar Sözcükler: Gecikme, siyalizasyonlu kavşak, Elmas şeklinde kavşak, Imam Hamza kavşağı, Hizmet seviyesi, Trafik sıkışıklığı, Gecikme süresi maliyeti. Master of Science in Civil Engineering. Thesis (M.S.)--Eastern Mediterranean University, Faculty of Engineering, Dept. of Civil Engineering, 2014. Supervisor: Assist. Prof. Dr. Mehmet Metin Kunt.

Queueing models for multi-service networks

Scipedia content — Tue, 26 Jan 2021 13:39:25 +0100

von Gerald Franzl Zsfassung in dt. Sprache Wien, Techn. Univ., Diss., 2015 OeBB

Rheological behaviour of Na-CMC and Na-alginate as binders for lithium ion batteries

Scipedia content — Tue, 26 Jan 2021 13:39:04 +0100

eer-reviewed Lithium ion batteries are the current technology of choice for electric vehicles due to their light weight, high volumetric and gravimetric energy density, low selfdischarge rate, quick charge acceptance, excellent cycle life and wide operating temperature range. However the current manufacturing process requires the use of polyvinylidene fluoride (PVDF), in order to bind the anode components within the electrode which prevents the recycling of the electrode materials. Furthermore PVDF necessitate the application of N-methyl-2-pyrrolidone (NMP), an environmentally toxic material as a solvent during the manufacturing. The aim of this research was to investigate the suitability of using water soluble Na-alginate as an alternative binder for the anodes of lithium ion batteries to reduce the environmental impact from current manufacturing processes and to allow recycling of the active anode components. The main function of the binder is the improvement of the mechanical strength and the adhesion of the electrode on the current collector. The properties of the binder which are most important during manufacturing are the rheological characteristics of the slurries comprising binder and active materials. This was the focus of this investigation. The viscosity of Na-alginate suspensions at 1% or 1.5% loading in water were typically 1 to 8 Pa·s which are similar to PVDF suspensions with loadings of 2.5 to 3.0%. Comparing to the benchmark Na-CMC, the degree of flocculation shows that for the same concentration of binder in water, Na-alginate suspensions are more stable, Na-alginate has a degree of flocculation of 1.17 while for Na-CMC it was 1.90. The rheology measurements show that Na-alginate slurries have a higher viscosity than Na-CMC at a shear rate of 50 s-1 with that for a 1.5% of Na-alginate binder being 1.26 Pa·s while for Na-CMC it was for 0.20 Pa·s. The loss factor was lower for Na-alginate, between 2 and 3 against between 2.9 and 3.3 for Na-CMC, showing a more developed network structure. The casting and drying process, demonstrated that while 1.5% Na-CMC in water wasn´t sufficiently viscous to cast the slurries it was possible to do it with Naalginate

Watch Supervisor in a Remote Tower Centre

Scipedia content — Tue, 26 Jan 2021 13:38:04 +0100

Den här rapporten är en utredning och analys av lämpliga arbetsuppgifter och deras nödvändiga verktyg och hjälpmedel för en skiftledare, Watch Supervisor, vid ett framtida center för fjärrstyrda flygledningstorn, Remote Tower. Ett center för fjärrstyrda flygledningstorn är en centraliserad enhet med uppgiften att flygleda och kontrollera flygsäkerheten på och nära en eller flera flygplatser. Utgångspunkten för datainsamlingen har varit intervjuer med verksamma flygledare och skiftledare på LFV, Sveriges statliga verk för flygtrafiktjänst. Studiebesök har även gjorts vid olika enheter, både flygledartorn och radarkontrollcentraler, däribland Sundsvall RTC som är världens första central för fjärrstyrd flygledning godkänd att sättas i drift. Insamlad data har kompilerats och analyserats och en rekommendation presenteras i slutet av denna rapport angående arbetsuppgifter och verktyg för ovan nämnda skiftledare i ett RTC. Resultatet visar att rollen kommer ha stora likheter med befintliga skiftledarpositioner i den svenska flygledningen.

Electric vehicles in action

Scipedia content — Tue, 26 Jan 2021 13:28:18 +0100

This thesis analyses the political and practical conditions for introducing electric vehicles in Swedish public authorites and discusses the potential for using electric vehicles in public transport and public fleets. The work has been carried out using an interdisciplinary research approach. Such an approach brings new insights to energy studies; the combination of technical methods and methods from social science allows the technology to be studied in its societal context. Local self-government enables Swedish public authorities to implement local solutions in order to achieve national policy goals. However, the results show that for energy and transport policy a clear allocation of responsibilities between local and regional levels is lacking – and this clarity is also lacking between the different policy areas. The lack of policy integration implies a risk that local policy development can miss the mark when it comes to the overall policy goal. Furthermore, findings show that so-called policy entrepreneurs can succeed in putting electric vehicles on the political agenda, and they can enforce decisions and deploy the vehicles within the public bodies. The usage of plug-in electric vehicles in public fleets has been studied using (among other sources) logbooks, interviews, questionnaires and focus groups. Findings demonstrate a great potential to introduce plug-in electric vehicles through fleets. Although the usage varied slightly during the year, and winter conditions implied a general reduction in use, the results show that the deployment strategy is a central factor for the extent of the vehicle usage. Vehicles that are assigned a certain user or a specific task show a high degree of utilisation. Even though plug-in electric vehicles available through car-pools have a large potential group of users, the options also implies that users can instead choose a conventional vehicle. However, interventions to increase usage have proven to be successful. Policy entrepreneurial actions attract new users and revising organisational regulations, i.e. vehicle or environmental policies, shapes new behaviours. In this study, fleet vehicle users have proven to be relative indifferent to which fuel or technology they use, but acceptance for operation failure is very low. Based on a demonstration project of series hybrid buses in regular service, the possibility of increased electrification of public transport is discussed. The contribution of hybridisation is analysed through assessment of different types of driving conditions. Results show that significant improvements in energy efficiency can be achieved but, because actual and optimal driving conditions differ, there is a risk of overestimating the contribution. Sweden has set very ambitious national targets for its road transport system, i.e. to be fossil-fuel independent by 2030, and electrification is an important measure in reaching this goal. Given the magnitude of the challenge, it is not only the responsible thing to do; findings also show several advantages of introducing electric vehicles in the public sector first. "p"QC 20150916

Assessment of impacts of electric vehicles on low voltage distribution networks in Turkey

Scipedia content — Tue, 26 Jan 2021 13:21:48 +0100

The number of Electric Vehicles (EVs) has reached a substantial value all over the globe due to economic and environmental factors. The increasing penetration of EVs to the distribution grids urges the requirement to investigate the impacts of EVs on the planning and operation of distribution networks. Despite the fact that there are numerous studies discussing the impacts of EVs on distribution grids, a particular study concerning the Turkish distribution networks does not exist. Therefore, this study focuses on analyzing the impacts of EVs on low voltage distribution networks in Turkey. Three distribution network models, two of them belonging to actual Turkish distribution network segments and one being generic, including different customer attributes and network structures are constructed and utilized throughout this study. An extensive EV model is developed using probabilistic models and assumptions. Gaussian distribution function for EV plug-in times and Weibull distribution function for daily travel times are adapted in Digsilent PowerFactoy simulation tool.Monte Carlo based load flow simulations are performed in order to evaluate the response of the distribution networks to various EV and load scenarios considering different multi-tariff mechanisms. Furthermore, a methodology is developed to obtain and present network results based on transformer and cable overloads, voltage drops, and grid losses. This methodology will help the decision maker determine the necessary investments on the distribution networks and associated time frames. This approach will improve the planning process of distribution companies. Hence, distribution companies will submit more realistic and accurate investment plans to the regulatory agencies. M.S. - Master of Science

Transit Signal Priority with Connected Vehicle Technology

Scipedia content — Tue, 26 Jan 2021 13:19:09 +0100

Transit Signal Priority (TSP) has been proposed and studied as a control strategy that offers preferences to transit vehicles at signalized intersections. Conventionally, many challenges have been identified that are preventing the TSP to be widely deployed, for example, adverse effect on side streets, and uncertainty of benefit. Closer investigation on these challenges reveals that these shortcomings are mainly caused by the fact that the logic of conventional TSP is based on data collected from the past instead of the present. If with real time data, many uncertainties can be eliminated, and correspondingly, TSP could perform better with higher reliability. The emerging new system known as connected vehicles is able to feed TSP with present data and also create many other possibilities for the TSP. In a connected vehicles environment, diagnostic sensors are installed on every vehicle to collect data and data are being transmitted wirelessly between vehicles and nearby infrastructures. It no longer has to rely on conventional data collection equipment, like loop detector or video detections, and it collects much more information than the conventional ways. Measurements that are previously unknown are now available, which include but not be limited to: vehicle speeds, positions, arrival rates, rates of acceleration and deceleration, queue lengths, stopped time and so on. A system of bus priority techniques is developed, taking advantages of the resource provided by Connected Vehicles (CV) technology, including two-way communications between the bus and the traffic signals, accurate bus location detection and prediction, and other information. The TSP logics allow cooperative control that traffic signal and transit bus work together. The cooperation requires a bus to travel at a reasonable speed which is recommended based on road geometry, normal signal timing plan and remaining/expected queue. The TSP strategy used is the green time reallocation, which only moves green time instead of adding extra green time. The TSP is also designed to be conditional on certain criteria. Delay per person is used as one of the most important criterion to decide whether TSP shall be granted. The developed TSP techniques are able to accommodate: single TSP request at an isolated intersection, bus merging at a nearside bus stop, multiple conflicting TSP requests at an isolated intersection and bus progression along a corridor. The logic developed in this research is evaluated in two ways: with analytical and microscopic simulation approaches. The proposed TSP techniques are usually compared against two scenarios: no TSP and conventional TSP. The measures of effectiveness (MOE) used are bus delay and per person delay of all travelers. Simulation-based evaluation results show that, compared to conventional TSP, the proposed TSP logic reduces bus delay of a single TSP request between 9% and 84%, minimizes bus delay during conflicting requests between 5% and 48%, decreases delay of buses progressing along a corridor between 35% and 68%, and cut back up to 30% of delay buses lose at merging from nearside bus stops. The range of improvement corresponding to the four different v/c ratios tested, which are 0.5, 0.7, 0.9 and 1.0. In most cases, no significant negative effects are caused by the proposed TSP logic.

Efficient city logistics : Can travel patterns of goods and people be intertwined?

Scipedia content — Tue, 26 Jan 2021 13:12:53 +0100

Optimizing city logistics is a topic of great importance for big cities today. Even though the environmental- and economical consequences of the increasing goods transportation fleet has been present for quite some time, actions from affected stakeholders has not been taken until just recently. In this brief 9 week project the aim has been to, from a design point-of-view, in this complex topic, give a suggestion and raise a discussion onto how goods transportation in cities can be made in the future. The basic idea is to get the consignments as close to the consignees and their travel patterns as possible. Public transportation networks are an existing grid where people are moving around and can potentially be used for combined transport of goods and people. The outcome of this concept is focusing on light parcel delivery towards private consignees, due to the increasing e-commerce trend. By using small transporter vehicles connected to buses, light parcels can be distributed throughout a city and easily accessible for consignees at the bus stops. The transporter vehicle developed through this project aims to conceptualize connectivity and integration between mobility and parcel delivery services, to ease the every day life of urban citizens as well as decrease the environmental- and economical impacts which the distribution vehicle-fleet of today entails. The design of the transporter vehicle is an interpretation of how a autonomous distribution vehicle can look like in a future city environment where the integration of public-utility-vehicles is of greater importance.

Route Clustering for Strategic Planning in Air Traffic Management

Scipedia content — Tue, 26 Jan 2021 13:11:20 +0100

The volume of air traffic in the National Air Space has been growing at a very fast pace during recent years, and increasing demand for air travel in coming years is predicted. Strategic Planning is a necessary tool to guarantee a safe and efficient increase of Air Traffic. An Aggregate Model for Strategic Planning of Air Traffic Management is the framework of this project.Aggregate models require the creation of a network that is representative of the expected flow and which will serve as a platform to solve flow optimization problems. We have integrated an automatic method for route clustering - Smax method - to generate the required network. Automatic clustering is necessary in order to efficiently cluster many individual scenarios.Some available alternatives to determine the number of clusters are tested. The studied alternatives provide success rates that oscillates between 49% and 68%. In addition to the relatively low success rates, these methods require one user-input parameter, and they are highly sensitive to it.A different method, based on the Silhouette Score and the Dip Test measures, is developed. The Smax method requires no user-input parameters, and it consistently provides rates of success that approximately oscillate between the 72% and the 81%.The presented clustering approach noticeably improves the rate of correct clustering cases for the specific scenario of route clustering.

Supporting electric vehicles in freight transport in Amsterdam

Scipedia content — Mon, 25 Jan 2021 20:22:55 +0100

Report written within the framework of Activity 7.4 of the Interreg IVB project E-Mobility NSR, file nr. 35-2-6-11. During the last decade the Municipality of Amsterdam has initiated quite elaborate policies to improve the air quality within the city, both for reasons of public health and spatial development. These policies were redefined in 2011 and subsequently evaluated and updated in 2013 (Gemeente Amsterdam, 2011a/b; 2013a). The main focus of these policies is on the reduction of NO2 and small particulate matter emissions. Supporting electric mobility - for freight as well as passengers - is an explicit part of these policies, rather than a goal in itself. With regard to the current ‘action plan’ this implies that two different approaches could be imagined. First, to take current air quality policies as a starting point and zoom in on the role of electric freight vehicles. Or, secondly, to focus explicitly on the latter, thus largely ignoring the prevailing focus applied by the Municipality of Amsterdam for several years now. We decided to choose the first approach, because it appears more realistic to connect to prevailing insights and policies than to ‘reinvent the wheel’. Moreover, we also took into consideration that transnational learning is one of the objectives of Activity 7.4 of the E-Mobility NSR project, and indeed of Interreg as such. This means that whereas the already relatively elaborate - and evaluated - policies in Amsterdam may leave limited opportunities for additional recommendations, they may have a distinct added value for other cities. Local policy in Amsterdam to support clean freight transport - and clean transport in general - applies a twofold approach: - an explicit focus on air quality norms, specifically those for NO2 and PM10 emissions, rather than on electric mobility as a aim in itself. EVs are supported, though, as a means to meet the air quality norms; - a strong focus on the cost efficiency of policy measures, in order to achieve a maximum improvement in air quality for the given budget. Amsterdam has been the first city to calculate the cost efficiency of measures in detail. This means in practice that measures focus on a limited number of locations where NO2 norms are exceeded. Also, measures focus on this categories of vehicles that generate the largest share in emissions, partly because they are large and heavy (trucks), partly because they make the most vehicle kilometres (vans, taxis). Results so far have been good, but less than expected and hoped for. Several reasons may be indicated for this: - the reductions in emissions from Euro 4 and 5 vehicles were much less than expected; - initial expectations concerning the number of EVs and Euro 6 vehicles that could be introduced have been too high; - the availability of Euro 6 vehicles and electric trucks was less than expected; - the willingness of private parties to invest was less than expected due to the economic crisis. In terms of recommendations, some issues can be identified that may strengthen the position of electric freight transport within the prevailing policies: - it should be considered how to use subsidies in such a way that new initiatives are triggered to improve and demonstrate the reliability and usefulness of electric vehicles, since this remains a main worry for companies that consider electric mobility; - the municipality should use their influence, not as a policy-maker but as a large customer, to stimulate clean mobility, more so than it does at the moment; - urban distribution deserves more emphasis, also taking into account the role of electric boats; - municipal bureaucracy, and divergence of rules between cities and countries remains a problem for firms considering electric mobility; - the results of policy and of pilot studies so far indicate that at the current stage of development, electric freight transport requires a tailor-made concept and approach such as city logistics. From the quite elaborated policy in Amsterdam some lessons can be drawn that may also be of use for other cities: - Amsterdam’s policy is characterized to a considerable degree by pragmatic, small, local and efficient interventions, strongly focused in terms of vehicle categories and locations; - it focuses on measures that generate the most effect per euro invested. This approach is based on elaborate calculations that resulted in the Cost Abatement Curve that guides the selection of policy measures.

Measurement of the Logistic Customer Service Level in Commercial Cargo Motor Transport Companies

Scipedia content — Mon, 25 Jan 2021 20:17:15 +0100

"jats:p" The term of logistic customer service is defined as the abilities or skills to meet the customer’s requirements and expectations, chiefly in terms of the time and place of deliveries, while using all available forms of logistic activity, including transport, storage, and the management of inventories, information and packages. As each of the logistic activities has an effect on the customer receiving right product or service, in its proper condition, in the correct time and space, and at reasonable costs, so seeking the proper service comes down to managing logistic activities in such a manner, as to achieve the essential level of customer satisfaction at the lowest possible costs. "/jats:p" "jats:p"The identified elements of logistic customer service in an organization are placed on a specific level, as assessed from the perspective of the purchasers' expectations. Among various methods for measuring customer service level, or quality, which are described in the literature on the subject, the SERVQUAL is recognized as one of the most effective. The SERVQUAL method relies on measuring the differences that exist between the quality, as perceived by a customer, and the quality demanded by that customer from a specific service. In order to determine the difference, both the customer's expectations for the service level, and their fulfilment by a specific organization need to be examined at the same time. "/jats:p" "jats:p"The elements of logistic customer service of the Silesian Province’s (region in southern Poland) commercial cargo motor transport enterprises under study are placed on a measurable level, as evaluated from the perspective of the recipients of offered transport services. The measurement of the logistic customer service level, as found in the entities examined, was made using the SERVQUAL method. The survey questionnaire used in the study was constructed based on 22 logistic customer service determinants. Questionnaire forms were filled by 294 customers of 147 Silesian Province’s commercial cargo motor transport enterprises examined, i.e. two customers of each enterprise. "/jats:p" "jats:p"The article presents theoretical basis for the measurement of the logistic customer service level by the SERVQUAL method, description of acquiring the research material, analysis of examination results and conclusions.

Document type: Article

Urban Policies on Diversity in Toronto, Canada

Scipedia content — Mon, 25 Jan 2021 20:11:15 +0100

Critical analysis of existing urban policy programmes and discourses in Toronto, Canada. Includes overview of political systems and governance structures, key shifts in national discourses, and approaches to policy over migration, citizenship, and diversity.

Shipping emissions in ports

Scipedia content — Mon, 25 Jan 2021 20:02:35 +0100

Shipping emissions in ports are substantial, accounting for 18 million tonnes of CO2 emissions, 0.4 million tonnes of NOx, 0.2 million of SOx and 0.03 million tonnes of PM10 in 2011. Around 85% of emissions come from containerships and tankers. Containerships have short port stays, but high emissions during these stays. Most of CO2 emissions in ports from shipping are in Asia and Europe (58%), but this share is low compared to their share of port calls (70%). European ports have much less emissions of SOx (5%) and PM (7%) than their share of port calls (22%), which can be explained by the EU regulation to use low sulphur fuels at berth. The ports with the largest absolute emission levels due to shipping are Singapore, Hong Kong (China), Tianjin (China) and Port Klang (Malaysia). The distribution of shipping emissions in ports is skewed: the ten ports with largest emissions represent 19% of total CO2 emissions in ports and 22% of SOx emissions. The port with the lowest relative CO2 emissions (emissions per ship call) is Kitakyushu (Japan); the port of Kyllini (Greece) has the lowest SOx emissions. Other ports with low relative emissions come from Japan, Greece, UK, US and Sweden. Shipping emissions have considerable external costs in ports: almost EUR 12 billion per year in the 50 largest ports in the OECD for NOx, SOx and PM emissions. Approximately 230 million people are directly exposed to the emissions in the top 100 world ports in terms of shipping emissions. Most shipping emissions in ports (CH4, CO, CO2 and NOx) will grow fourfold up to 2050. This would bring CO2-emissions from ships in ports to approximately 70 million tonnes in 2050 and NOx-emissions up to 1.3 million tonnes. Asia and Africa will see the sharpest increases in emissions, due to strong port traffic growth and limited mitigation measures. In order to reduce these projected emissions, strong policy responses will be needed. This could take the form of global regulation such as more stringent rules on sulphur content of ship fuel, or more emission control areas than the four that are currently in place. In addition, shipping could be included in global emissions trading schemes and climate finance schemes. A lot could also be gained by policy initiatives of ports themselves. Various ports have developed infrastructure, regulation and incentives that mitigate shipping emissions in ports. [...]

Rethinking Youth, Livelihoods, and Fragility in West Africa : One Size Doesn’t Fit All

Scipedia content — Mon, 25 Jan 2021 19:42:20 +0100

frica’s population is young and growing at twice the pace of other continents. A youth bulge presents a series of development policy opportunities and challenges. In this context, simplistic linkages between the youth bulge, high unemployment, and fragility have gained traction and given rise to a youth policy agenda that targets urban male youth as the problem and emphasizes formal sector development as the solution. This paper questions some of the core assumptions that underpin mainstream perceptions of the linkages between youth, employment, and fragility in West Africa, and presents an alternative analysis. The study will use the language of livelihoods to reflect on youth employment experiences, as livelihoods take into account the capabilities, assets (including both material and social resources), and activities required for a means of living beyond traditional ideas of employment, and thus enable a deeper, more sophisticated understanding of the realities of many young West Africans. The paper argues that a nuanced understanding of specific groups of young people and their livelihood activities in their specific social, cultural, political, and economic context is necessary to understand how young peoples’ lives intersect with fragility dynamics. The paper aims to highlight that the relationship between youth, unemployment, underemployment, livelihoods, and fragility is far more complex than is often recognized and should not be exaggerated or taken out of context.