Scipedia: Documents published in 2012

Speed and Path Control for Conflict-Free Flight in High Air Traffic Demand in Terminal Airspace

Scipedia content — Tue, 26 Jan 2021 18:20:48 +0100

To accommodate the growing air traffic demand, flights will need to be planned and navigated with a much higher level of precision than today's aircraft flight path. The Next Generation Air Transportation System (NextGen) stands to benefit significantly in safety and efficiency from such movement of aircraft along precisely defined paths. Air Traffic Operations (ATO) relying on such precision--the Precision Air Traffic Operations or PATO--are the foundation of high throughput capacity envisioned for the future airports. In PATO, the preferred method is to manage the air traffic by assigning a speed profile to each aircraft in a given fleet in a given airspace (in practice known as ("italic"speed control"/italic"). In this research, an algorithm has been developed, set in the context of a Hybrid Control System (HCS) model, that determines whether a speed control solution exists for a given fleet of aircraft in a given airspace and if so, computes this solution as a collective speed profile that assures separation if executed without deviation. Uncertainties such as weather are not considered but the algorithm can be modified to include uncertainties. The algorithm first computes all feasible sequences (i.e., all sequences that allow the given fleet of aircraft to reach destinations without violating the FAA's separation requirement) by looking at all pairs of aircraft. Then, the most likely sequence is determined and the speed control solution is constructed by a backward trajectory generation, starting with the aircraft last out and proceeds to the first out. This computation can be done for different sequences in parallel which helps to reduce the computation time. If such a solution does not exist, then the algorithm calculates a minimal path modification (known as "italic"path control"/italic") that will allow separation-compliance speed control. We will also prove that the algorithm will modify the path without creating a new separation violation. The new path will be generated by adding new waypoints in the airspace. As a byproduct, instead of minimal path modification, one can use the aircraft arrival time schedule to generate the sequence in which the aircraft reach their destinations.

Collective transportation policies in São Paulo between 2001 and 2010: built environment, technical systems and organization of transport services

Scipedia content — Tue, 26 Jan 2021 18:17:59 +0100

presente pesquisa analisará as características das políticas de transporte coletivo no Município de São Paulo, entre os anos de 2001 e 2010. Partindo do entendimento do modelo de desenvolvimento urbano vigente, o qual priorizou o transporte privado sobre rodas, individual, além de um perfil sócio-espacial segregador procuraremos definir quais foram as principais ações realizadas neste setor, considerando: a evolução histórica das políticas de transporte a partir do início do século XX; principais políticas públicas de transporte a partir de 2001 (implementações de corredores de ônibus, integração de modais, implantação de bilhete único etc); análise das repercussões destas políticas na dinâmica concreta da mobilidade urbana. Também pretendemos interpretar as relações das administrações municipais que governaram a cidade nesse período (gestão Marta Suplicy 2001 - 2004 - gestão José Serra/Gilberto Kassab 2005 - 2008 - e gestão Gilberto Kassab 2009 - 2010) com os principais agentes urbanos envolvidos (elite política municipal, empresários e empreendedores urbanos, sociedade civil e usuários de transportes públicos e privados, principalmente) e outros grupos de interesse, analisando de que maneira e por meio de quais instrumentos as políticas públicas de mobilidade urbana foram desenvolvidas. This research aims to analyze the characteristics of collective transportation policies in São Paulo, between 2001 and 2010. Based on the understanding of the current urban development model, which gave priority to individual and private transport on wheels, as well as a socio-spatial segregated role - we will try to define what were the main actions undertaken in this sector, considering: the historical evolution of transport policies from the early twentieth century, major public transport policy since 2001 (implementation of bus corridors, modal integration, implementation of the Bilhete Único ticket etc.), analysis of the impact of these policies on the dynamics of the urban mobility. We also intend to interpret the relationships between the municipal administrations that governed the city during this period (governments of Suplicy - 2001 2004, Serra / Gilberto Kassab - 2005 2008, and Gilberto Kassab - from 2009 to 2010) with the main agents involved with the urban dynamics (municipal political elite, businessmen and urban entrepreneurs, civil society and users of public and private transport, mainly) and other interest groups, analyzing how and through which instruments the urban mobility public policies have been developed.

A New Procedure for Scoring Rail Transit Connections to U.S. Airports

Scipedia content — Tue, 26 Jan 2021 18:12:44 +0100

25 airports have a connection with the local rail transit system, but each is unique. Variables such as network size, train frequency, type of airport station, time, and cost vary by airport. Both airport passengers and planners should have a technical basis of selecting which system is the most useful, efficient, and reliable. To date, there have been no scoring procedures created to rank the airports in order of quality of connection. This thesis analyzes rail transit accessibility for all 25 airports (3 of which have 2 separate transit systems) by investigating 8 characteristics, 3 of which are market factors and 5 of which are system factors. The 5 system factors are travel time difference between car and train, transit cost difference between car and train, airport/transit connection type, network size, and train frequency. The 3 market factors are rail transit mode share, business traveler percentage, and low-cost carrier percentage. A scoring system was then developed and each airportâ s characteristics were inputted. The airports were scored using three different methods and were subsequently evaluated to understand why airports received the scores they did. This evaluation led to a better understanding of airport transit best practices. The scoring system was used again to evaluate an airport (Washington-Dulles) undergoing radical changes to understand by what factor a score can improve. A â top 10â list of airport transit connections was produced with JFK coming in first. This method is a starting point for developing a robust system to evaluate transit connections to airports. Master of Science

Vehicle routing with time windows using generic algorithm.

Scipedia content — Tue, 26 Jan 2021 18:10:36 +0100

O componente de planejamento faz parte do projeto de desenvolvimento dos veículos autônomos, e é responsável por gerar rotas para o sistema como um todo. Em aplicações em que o veículo deve visitar pontos em intervalos de tempo pré-determinados, o componente de planejamento se enquadra em um problema de roteirização conhecido da literatura, denominado problema de roteirização de veículos com janelas de tempo. Tal problema é uma generalização do problema clássico de roteirização de veículos classificado no grupo de problemas NP-Hard. Esse trabalho apresenta uma proposta de solução para o problema baseada na metaheurística algoritmo genético. Os cromossomos foram representados pela ordem de atendimento dos clientes sem delimitadores de rota. Para quebrar os cromossomos em rotas, foi utilizado um procedimento adaptado baseado em Prins (2004). A população inicial se constitui por uma parte construída com cromossomos criados aleatoriamente e outra parte construída através da heurística de inserção I1 de Solomon (1987), com quatro formas diferentes de inserir o primeiro cliente de cada rota. Na fase de recombinação, foram utilizados quatro tipos de crossover: uniforme, dois pontos, heurístico e PMX, e um operador de mutação baseado em uma busca heurística. A cada geração foram aplicados princípios de elitismo e pós-otimização utilizando a heurística -interchange de Osman (1993). O algoritmo foi testado nos conjuntos C1, C2, R1, R2, RC1 e RC2 de Solomon (1987) e os resultados foram comparados com os melhores resultados encontrados na literatura. The planning component is a part of autonomous vehicle development project and it is responsible to generate routes for the system as a whole. In applications which vehicle must to visit way points at predetermined intervals of time, the planning component fits into a routing problem known in the literature called routing problem with time windows. This problem is a generalization of the classical vehicle routing problem classified in the group of NP- Hard problems. This thesis presents a solution proposal to problem based on genetic algorithm metaheuristic. Chromosomes were represented by the order of serving customers without delimiters route. To split the chromosomes on routes, it is used a procedure adapted based on Prins (2004). The initial population is constituted by two parts: one with randomly created chromosomes and another constructed through the insertion heuristic I1 of Solomon (1987), with four different ways of insertion of the first customer of each route. In the recombination step, four types of crossover were used: uniform, two points, heuristic, and PMX, and a mutation operator based on heuristic search. In each generation it is applied principles of elitism and postoptimization using the -interchange heuristic of Osman (1993). The algorithm was tested on the sets C1, C2, R1, R2, RC1 and RC2 of Solomon (1987) and the results were compared with the best results found in the literature.

Development and evaluation of a range anxiety-reducing business model for connected full electric vehicles

Scipedia content — Tue, 26 Jan 2021 18:08:57 +0100

Submitted by Eliene Soares da Silva (eliene.silva@fgv.br) on 2012-11-26T14:59:25Z No. of bitstreams: 1 FINAL THESIS_Sven Kämmerer.pdf: 4409442 bytes, checksum: f0b4d51fcb5997ef130c873c65386e15 (MD5) Approved for entry into archive by Eliene Soares da Silva (eliene.silva@fgv.br) on 2012-11-26T15:03:02Z (GMT) No. of bitstreams: 1 FINAL THESIS_Sven Kämmerer.pdf: 4409442 bytes, checksum: f0b4d51fcb5997ef130c873c65386e15 (MD5) Made available in DSpace on 2012-11-26T15:16:15Z (GMT). No. of bitstreams: 1 FINAL THESIS_Sven Kämmerer.pdf: 4409442 bytes, checksum: f0b4d51fcb5997ef130c873c65386e15 (MD5) Previous issue date: 2012-09-27 This thesis develops and evaluates a business model for connected full electric vehicles (FEV) for the European market. Despite a promoting political environment, various barriers have thus far prevented the FEV from becoming a mass-market vehicle. Besides cost, the most noteworthy of these barriers is represented by range anxiety, a product of FEVs’ limited range, lacking availability of charging infrastructure, and long recharging times. Connected FEVs, which maintain a constant connection to the surrounding infrastructure, appear to be a promising element to overcome drivers’ range anxiety. Yet their successful application requires a well functioning FEV ecosystem which can only be created through the collaboration of various stakeholders such as original equipment manufacturers (OEM), first tier suppliers (FTS), charging infrastructure and service providers (CISP), utilities, communication enablers, and governments. This thesis explores and evaluates how a business model, jointly created by these stakeholders, could look like, i.e. how stakeholders could collaborate in the design of products, services, infrastructure, and advanced mobility management, to meet drivers with a sensible value proposition that is at least equivalent to that of internal combustion engine (ICE) cars. It suggests that this value proposition will be an end-2-end package provided by CISPs or OEMs that comprises mobility packages (incl. pay per mile plans, battery leasing, charging and battery swapping (BS) infrastructure) and FEVs equipped with an on-board unit (OBU) combined with additional services targeted at range anxiety reduction. From a theoretical point of view the thesis answers the question which business model framework is suitable for the development of a holistic, i.e. all stakeholder-comprising business model for connected FEVs and defines such a business model. In doing so the thesis provides the first comprehensive business model related research findings on connected FEVs, as prior works focused on the much less complex scenario featuring only 'offline' FEVs.

Incoming Interdomain Traffic Engineering with LISP: Evaluation of LISP traffic engineering capabilities compared with BGP for stub AS

Scipedia content — Tue, 26 Jan 2021 18:08:21 +0100

Mit der immer stärker werdenden Zunahme von Internet-Traffic wird die Bedeutung von Traffic- Engineering auch in Stub-Systemen immer wichtiger. Während es mit den aktuellen Techniken wie BGP vergleichsweise einfach ist, den Traffic in ausgehender Richtung zu verteilen, ist es umso schwieriger, den vom Provider eingehenden Traffic auf die verfügbaren Leitungen zu verteilen. Insbesondere gilt dies im Fall von Multi-Homing mit mehreren Providern (aber auch bei nur einem Provider), da es keine Möglichkeiten gibt, den Traffic in anderen Systemen als dem eigenen zu kontrollieren. Heutige Methoden wie BGP und dessen Varianten verwenden häufig heuristische und zeitaufwändige Verfahren, die lediglich ungenaue Resultate liefern. Im Rahmen dieser Arbeit soll untersucht werden, ob es mit Hilfe des Locator/Identifier Separation Protocol (LISP) eine effektivere Möglichkeit gibt, den eingehenden Internetverkehr zu verteilen. Zu diesem Zweck werden Messungen in einem Labornetzwerk durchgeführt. Untersucht werden hierbei reines BGP sowie dessen Varianten "Advertisement of more specific prefixes" und "AS Path Prepending" (ASPP). Der Vergleich mit LISP zeigt, dass LISP erheblich einfacher zu implementieren ist als BGP und weiterhin Load-Balancing mit einer Genauigkeit von 5% erlaubt. Diese Resultate sind unabhängig von der Verteilung des eingehenden Traffics, der Anzahl gleichzeitiger Streams und auch bei zufälligem Traffic.

Switched Reluctance Motors for Electric Vehicle Propulsion - Optimal Machine Design and Control/Machines à réluctance variable utilisées pour la propulsion des véhicules électriques - Conception et Contrôle optimal

Scipedia content — Tue, 26 Jan 2021 18:07:32 +0100

1. Chapter 1. Introduction In Chapter 1 the actual context of electrified vehicles is presented. The paradigm shift in the auto industry, towards more energy efficient, more reliable and smarter vehicles led to the development of electrified vehicles such as the more electric vehicles (MEVs), hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs) and electric vehicles (EVs). Excepting the MEVs, all other classes are equipped with at least one motor/generator used for propulsion/braking. As for the energy they need to be fed with, it can be drawn from multiple sources, such as: chemical batteries, fuel cells (FCs) or ultra-capacitors. Comparative tables regarding potential electric machines to be used in the EV development are provided. Efficiency, terminal quantities (current, voltage), rated and maximum torque and speed are considered for comparison, amongst other quantities. Moreover the advantages as well as drawbacks are mentioned for three other classes of electrical machines, i.e. DC machine, induction machine, permanent magnet synchronous machine. The main advantages of the SR technology over the rest of the machines are discussed along with its main drawbacks. Finally some of the most representative work in the field performed by both Universities and industry is mentioned. Next, the main contributions of the thesis are pointed out in the second section of the chapter while in the last section the outline of the thesis is performed. 2. Chapter 2. Electromagnetic Model of an SRM In Chapter 2 a FE-based electromagnetic model is developed for accurately characterizing the (nonlinear) behavior of SRMs. Having the correct set of curves is rather decisive if one intends to perform high-grade control as the flux and ultimately the torque depends on both position and current. After an extensive review of the methods existing in the field for magnetic characterization, three important classes emerged. Therefore, such curves can be obtained either using empirical formulas, FE models, or measured. In this Chapter two different approaches are considered for determining the flux and eventually the torque dependence with current and position. In the first case, the magnetization characteristics are obtained based on FE analyses. Moreover the flux variation with position is compared using 2D and 3D FE models. The 2D model has been developed in FEMM software which was preferred due to its convenient interface with Matlab. Following another literature review where the effect of using the 2D FE model vs. the 3D ones are highlighted, a 3D FE model is developed as well. The static flux curves obtained using the 2D FE model are compared with the 3D FE obtained ones, in two cases: the 3D model is obtained through extrusion of the 2D model (end-windings are not modeled) and the 3D model is including the end-windings. As expected the difference between the 2D FE model and its extruded counterpart is insignificant. On the other hand, when the end-coils are modeled, the difference is rather important as it is the case of the unaligned position where it can be more flux up 22%. However, this difference is reducing as the rotor is getting closer to aligned position, where it drops under 1%. Finally, the flux curves are determined based on an experimental procedure after the integration of the voltage equation where the (transient) current and (transient) voltage are measured by means of the DC-step voltage test, i.e. with the rotor blocked, a DC step voltage is applied to the phase at different angular positions and the current and voltage waveforms are recorded. A procedure for obtaining the torque from the polynomial fitted surface of coenergy is provided. It is shown that using the latter, the numerical problems which appear using the raw surface of the coenergy instead of the fitted one, are significantly reduced. In the last core-section of the chapter, a generalized procedure for iron losses calculation is proposed starting from a matrix-based model (previously presented in the literature), taking into consideration the fact that different segments in the SRM are subject to different fundamental frequency of the magnetic flux density. In addition, the rotational effect of the flux is taken into consideration as well as the minor loops effect. One, rather important part is the procedure for determining the time variation of magnetic flux density Using the time series of the phase current (obtained through dynamic simulations based on the circuit model) and the FE obtained tables for magnetic flux density dependence with rotor position and current, the instantaneous variation of the magnetic flux density is obtained. 3. Chapter 3. Thermal Model of an SRM The miniaturization of electrical motors is decisive when choosing one used for HEV/EV propulsion. Due to the lack of permanent magnets, SRMs are subject to high current densities in the coils so as to overcome the drawback of a lower power density. Special attention must be paid to the cooling arrangement in order to remove the excessive heat that results in the machine due to the increased copper losses as well as core losses at higher speed values. The chapter starts with a brief review on thermal modeling of electric machines. Some representative work that is reported on patent development for cooling arrangements of salient poles electric machines in general and SRM in particular, is mentioned in the patent review section of the chapter. In this chapter starting from the earlier works involving totally-enclosed non-ventilated (TENV) SRMs as well as totally-enclosed forced cooled (TEFC) induction machines, a lumped parameter thermal network (LPTN) is developed for a totally-enclosed water cooled (TEWC) SRM. The conductive parts are modeled based on the T-model described in earlier works for which the thermal resistances are calculated starting from the heat conduction equation (also known as Fourier’s law), to which some simplifying hypotheses are applied. Correlations are made for determining the convective heat transfer coefficients in the air-gap starting from Nusselt number calculated using the model of two rotating cylinders developed by Taylor, to which penalties (which are speed dependant) are applied in order to include the effect of the salient poles. For the end-cap air, a constant heat transfer coefficient as the air flow in the axial direction is neglected due to the lack of any fan coupled at the end of the shaft. Theoretical issues are provided regarding the thermal contact resistances, the heat transfer mechanism trough radiation and the circumstances in which it can be neglected as well as the calculation procedure for the thermal capacitances in order to include the transient evolution of temperature in the study. Moreover, the methodology for solving the equivalent circuit is given, both for steady and transient state using the matrix-based form of the method of node potentials (MNP). Next, a 2D model thermal FE model is developed for design optimization purposes. Furthermore, the temperature evolution in the thermally conductive segments of cross-section is determined based upon a 3D FE model and the temperature distribution is discussed considering different operating scenarios. The main heat transfer paths are discussed as well. Eventually, a comparison between the transient evolution of the temperature in the key conductive segments (stator and rotor iron, coils) when either using the LPTN or the 3D FE model. The main conclusion of the chapter is that the LPTN may represent a viable solution for predicting the evolution in time of the temperature in an SRM. However there are few rather sensitive parameters that have to be determined either using more complex models such as 3D FE or CFD or based of measured data. Moreover, the latter has to be used for determining the distribution of the temperature in a certain segment. 4. Chapter 4. SRM Design This chapter deals with the design procedure of an SRM used in HEV/EV propulsion. A FE-based multiphysics design optimization routine is developed. Two different approaches are considered regarding the initial design. In the first case the topology is obtained using a pre-sizing routine while taking into account the requirements of an electric motor used for HEVs/EVs (referred in text as SRMPRE-S), whereas in the second case the performance of the multiphysics optimization routine is assessed starting from an existing SRM and trying to increase its torque density without modifying the outer envelope nor the cooling circuit (referred in text as SRMPPT). Three different types of constraints are embedded in the optimization routine. The electromagnetic ones are given by the magnetic flux density value (both in the stator pole and stator back iron) whereas the heat generation (thermal constraint) is controlled either by means of the current density, or coupling the analysis with the FE thermal one. Furthermore, at each evaluation the circumferential mode frequency for the pulsating vibration mode m = 2 is calculated and lower boundaries are considered for limiting the deterioration of the NVH properties. The outer envelope of the machine is not subject to any change as both the outer diameter and stack length have been kept constant. Moreover, a state of the art on SRM design is presented along discussions on the optimal design of SRMs. A rather significant increase in the torque density is reported as output of the optimization routine (up to 25%) for slight decrease in efficiency (less than 1%). 5. Chapter 5. Torque Control of SRMs Chapter 5 starts with a review on some of the works conducted over the last decades in torque control and the methods proposed by the author for overcoming the main drawbacks of the SRM a the control level. It continues with a brief description of the torque production mechanism in SRMs followed by the description of the optimization problem as well as the minimization technique that is used. The positioning of the minimization technique that is used in the frame of the minimization techniques is briefly discussed as well. The flux and torque curves, determined based on the FE-model in Chapter 2, are used for developing the dynamic model of the SRM. In order to improve the convergence performance of the optimization routine, a smooth model has been developed, which in addition allowed for the separation of the two causes of ripple. Further the torque control is optimized over the entire speed range, by splitting up the problem in two as follows. At low speed an instantaneous torque control (ITC) technique is implemented by means of modeling the required shape of the current using the so-called torque sharing functions (TSFs), whereas at higher speed an average torque control (ATC) technique is considered to be sufficient. Regarding the ITC, starting from the basic rectangular variation, the ascending and descending flanks of the function are modeled using a cosine, exponential and a more general approach (further referred to as piecewise cubic sharing function). The degrees of freedom (DOFs) varying between two and an arbitrary number (for the general approach) are determined so as to minimize losses, when operating in smooth torque conditions. Based upon an optimization procedure with both linear and nonlinear constraints, the total (copper and iron) losses are minimized considering a limited available DC bus voltage. Extensive studies have been conducted for determining the optimal number of degrees of freedom (DoFs) for the piecewise cubic function. At speed values exceeding 1000rpm the average values of the torque is controlled and the optimal values for the firing angles are obtained based on a minimization routine for different objective functions. Starting from the one variable functions step by step, penalties are added for improving the ripple content and eventually the efficiency. Moreover, the drawback of the minimization routines to converge to local minima is overcome by including special routines for initial conditions generation. Finally, for the optimal sets of angles (for both control schemes), losses (iron and copper) are evaluated both in motoring and generating mode. After conducting the optimizations over the entire considered torque-speed range it was found that the generalized version of the cubic variation provides the lowest copper losses as well as an extension of the torque-speed region in which the peak torque can be produced, ripple-free (around 30%). Extensive studies have been conducted for assessing the performance of the generalized TSF. Knowing the voltage dips are not an uncommon phenomenon in EV applications, tests have been executed for determining which is the allowed dip value so as to the torque ripple is not increasing significantly. The method was proven to be robust, as significant ripple occurred only when the voltage dropped to 0.25. A value equal to one corresponded to the rated DC bus value. Moreover, the influence of different switching strategies on the phase current tracking its reference was shown and a hybrid chopping technique was implemented in order to reduce the switching frequency, thus the losses in the converter. An extension of the piecewise cubic function to SRMs with more than two phases conducting in the same time is discussed theoretically but no results are provided as most of the work in this thesis is dedicated to the 8/6 topology. In the last section a series of measured results are provided for both torque control schemes starting from the low speed (250rpm) operation, continuing with base speed (1500rpm), then double the base speed (3000rpm) and eventually at the maximum speed specified for the load in its datasheet (4000rpm). Regarding the load torque, measurements were conducted up to 30Nm, limitation given by the load (7.5kW DC machine). Using the measured phase currents, the torque is estimated based on the FE calculated torque vs. current and position table, and eventually compared with that obtained by simulations. A good agreement between measured/estimated instantaneous torque and its simulated counterpart was obtained, when on the simulations the same sampling was imposed as it was for the test bench (10kHz). 6. Chapter 6. Assessing the Performance of an SRM in Various Driving Cycles In this chapter, starting from the losses (iron and copper) evaluated using the optimal sets of angles (for both control schemes) and for both motoring and generating mode the performances of the SRM and the proposed controller are assessed by applying different driving cycles. The considered cycles fall into one of the following categories: modal (characterized by long distances traveled at constant speed), transient (characterized by constantly varying speed). Also different driving areas as simulated when considering the MOL cycle in its three forms - city, highway and rural). A simplified model of an EV has been developed in order to determine the torque and speed command that have to be given to the SRM controller. Regarding the controller, it has been shown in previous chapter that there are two torque control technique embedded in it. Tests have been made to determine the optimal speed value at which the control schemes are swapped. It is shown that for the proposed configuration the current profiling technique can be used up to 1000rpm after this point an average torque control technique being sufficient. The LPTN developed in Chapter 3 has been used for thermal characterization of the SRM under different driving conditions (considered by means of driving cycles - both standard and real-life). Moreover, for the present configuration of the drive, after testing 5 driving cycles one may observe the rather safe operation, as the maximum allowable temperature is not reached. For driving cycles of city type the average efficiency obtained was around 80% whereas for the highway type efficiencies over 90% have been obtained. Considering a vehicle of 1950kg powered by a battery with a capacity of 30kWh, the estimated range is about 200km in the city type driving cycles, whereas when cruising on the highway it can drop to 120km. 7. Chapter 7. Conclusions and Future Work In Chapter 7 the main conclusions are drawn and some suggestions for future work are made. Moreover, each chapter has its own Appendix (from A to E) in which additional data is provided, in order to ensure the reproducibility of the work/results.

Doctorat en Sciences de l'ingénieur

info:eu-repo/semantics/published

Feasibility of dual-fuel engines in short sea shipping lines

Scipedia content — Tue, 26 Jan 2021 18:05:52 +0100

The main objective is to determinate the feasibility of Dual-Fuel retrofitting for engines present in Short Sea Shipping vessels. To accomplish this main objective there are other secondary objectives: - Integrate future environmental regulations to this paper forcing its achievement in this study - Determinate present day technologies capable to accomplish environmental regulations - Definition of shipping routes to study the proposed viability - Determinate the study vessel to obtain its measurements - Study Dual-Fuel, and other main engine types - Study Dual-Fuel and Scrubber System vessel’s retrofitting - Review of bunkering prices to do comparisons and to create different future scenarios according to the possible price evolution

Hava Trafik Kontrolünde Kontrolör Kararları Nedeni İle Oluşan Gecikmelerin Analizi

Scipedia content — Tue, 26 Jan 2021 17:48:35 +0100

Tez (Yüksek Lisans) -- İstanbul Teknik Üniversitesi, Fen Bilimleri Enstitüsü, 2013

Thesis (M.Sc.) -- İstanbul Technical University, Institute of Science and Technology, 2013

Bu çalışmada iki farklı veri seti kullanılarak, Avrupa Hava Sahası üzerinde bir takım analizler gerçekleştirilmiş ve bu hava sahasını modelleme yöntemlerinin verimliliği üzerinde durulmuştur. Öncelikle, Hava Trafiği modellerine ön ayak olması amacı ile Avrupa Hava Sahası üzerinde bulunan hava alanlarının ve hava limanlarının ayrı ayrı bağlantı grafları analizler için kullanılan veri setleri üzerinden oluşturulmuş ve trafik akışının karakteristikleri hakkında bilgi edinmek amacı ile Fransa Hava Sahası incelenmiştir. Bu noktadan sonra gecikme analizlerine geçilmiş ve yaşanan gecikmeler iki farklı bakış açısı ile incelenmiştir. İlk olarak her uçuş için uçuşun geçtiği tüm hava alanları üzerinde yaşadığı gecikmeler gerçek uçulan ve planlanan sürelerin farkı ile hesaplanmış ve uçuşun bütün fazlarındaki yaşadığı gecikmeler elde edilmiştir. Bütün uçuşların sonuçlarının birleştirilmesi üzerine, Avrupa hava sahası üzerindeki gecikme üretim dağılımları ve bu dağılımların zamanla nasıl ilerlediği elde edilmiş, gecikme üretimi açısından sorunlu bölgeler saptanmıştır. İkinci bir yaklaşım olarak hava limanları ağı üzerinde gecikmelerin nasıl ilerlediği araştırılmış ve farklı bir modelleme yöntemi önerilmiştir. Bu metodun hava limanları arasında gerçekleşen tüm uçuşları ayrı ayrı incelemesi nedeni ile temsil etme kapasitesi daha yüksek bir modelleme yöntemi olduğu sonucuna varılmıştır.

In this study by using two different sets of data, analyses have been conducted over European Airspace and the efficiencies for modelling techniques of European Air Traffic Network are investigated. Before all else, in order to be the initiator of an air traffic model of European Airspace, connectivity graphs of both airspaces and airports have been generated directly via utilization of data sets. To be able to have an insight about air traffic flow patterns and characteristics France Airspaces have been analyzed. From that point on, delay propagation analyses have been conducted and delays have been investigated with two different approach. Firstly, for every flight, delay of each crossed airspace has been calculated by seeking the difference between planned and actual data. Aggregation of all these delay data from every flight resulted with the distribution of delay generations across the whole European Airspace. Moreover, utilizing this method in a long time interval yielded the propagation of delays through time and gathering all these results together pointed out the congested regions with generally and/or highly delay generating regions. As a secondary modelling approach, analyses have been conducted over the connectivity graph of airports. All flights between each airport pair have been investigated along with airport analyses implemented with all flights regarding those airports. It has been observed that the second approach provides a more representative modelling method because it compares the flights between airport pairs with all other flights which gives more inferences for the reasons of delays and their propagations.

Yüksek Lisans

M.Sc.

Vehicle tracking and traffic monitoring at an intersection using an uncalibrated stereo vision system

Scipedia content — Tue, 26 Jan 2021 17:35:52 +0100

M.Ing. Traffic has become an extreme irritation and costly entity to deal with in recent years. Gone are the days where one could simply widen roadways to increase flow rates due to space constraints. Traffic costs countries billions of dollars per annum and thus the need to alleviate traffic congestion. Many technologies are currently available that can be used to lower the traffic density at an intersection, one of them being the use of cameras. Not only are digital cameras dropping in price, but the associated cost of maintenance is low. Distance information of a scene can thus be calculated via a visual system and from this information advanced control can be implemented in order to maximise traffic flow through an intersection. A traffic simulator was coded and analysed in order to validate the use of a visual system for increasing the amount of cars passing through the intersection per unit time over the current fixed timing system. Two different algorithms were compared to the current fixed timing scheme using a traffic simulator. The results showed that an improvement can be achieved over the current fixed timing scheme (of up to 19.92%). The use of stereovision as a method of attempting to monitor traffic flow is discussed. Vehicles were tracked using 13 trackers and the distance away from the stereo setup was calculated and compared to the actual distance away from the stereo setup. The best results found that with a baseline distance of 1500mm the average error in determining the distance of a vehicle was 16.46m. Although this error is quite large, it is still possible to monitor traffic flow using stereo vision with these inputs. Some of the issues that may cause these errors are camera quality, camera calibration and variable lighting conditions.

Route optimization and customization using real geographical data in Android mobile devices

Scipedia content — Tue, 26 Jan 2021 17:29:28 +0100

Nowadays, there are several services and applications that allow users to locate and move to different tourist areas using a mobile device. These systems can be used either by internet or downloading an application in concrete places like a visitors centre. Although such applications are able to facilitate the location and the search for points of interest, in most cases, these services and applications do not meet the needs of each user. This paper aims to provide a solution by studying the main projects, services and applications, their routing algorithms and their treatment of the real geographical data in Android mobile devices, focusing on the data acquisition and treatment to improve the routing searches in off-line environments.

Hoy en día hay varios servicios y aplicaciones que permiten a los usuarios localizar y trasladarse a diferentes zonas turísticas utilizando un dispositivo móvil. Estos sistemas pueden ser utilizados ya sea por Internet o descargar una aplicación en lugares concretos, como un centro de visitantes. A pesar de que estas aplicaciones son capaces de facilitar la localización y la búsqueda de puntos de interés, en la mayoría de los casos estos servicios y aplicaciones no se ajustan a las necesidades de cada usuario. Este trabajo tiene como objetivo proporcionar una solución mediante el estudio de los principales proyectos, servicios y aplicaciones, sus algoritmos de enrutamiento y su tratamiento de los datos reales geográficos en dispositivos móviles Android, centrándose en la adquisición de datos y tratamiento para mejorar las búsquedas de enrutamiento en entornos fuera de línea.

Avui dia hi ha diversos serveis i aplicacions que permeten als usuaris localitzar i traslladar-se a diferents zones turístiques utilitzant un dispositiu mòbil. Aquests sistemes poden ser utilitzats ja sigui per Internet o descarregar una aplicació en llocs concrets, com un centre de visitants. Tot i que aquestes aplicacions són capaces de facilitar la localització i la recerca de punts d'interès, en la majoria dels casos aquests serveis i aplicacions no s'ajusten a les necessitats de cada usuari. Aquest treball té per objectiu proporcionar una solució mitjançant l'estudi dels principals projectes, serveis i aplicacions, els seus algoritmes d'encaminament i el seu tractament de les dades reals geogràfics en dispositius mòbils Android, centrant-se en l'adquisició de dades i tractament per millorar les recerques d'enrutament en entorns fora de línia.

A study of electric vehicle charging patterns and range anxiety

Scipedia content — Tue, 26 Jan 2021 17:27:14 +0100

Range anxiety is a relatively new concept which is defined as the fear of running out of power when driving an electric vehicle. To decrease range anxiety you can increase the battery size or decrease the minimum state of charge, the least amount of power that can be left in the battery, or to expand the available fast charging infrastructure. But is that economical feasible or even technically possible in today’s society? In this project we have used a theoretical model for estimating range anxiety and have simulated the average electricity consumption using two different kinds of electric vehicles, to see how often they reach range anxiety according to a specific definition of range anxiety implemented in this model. The simulations were performed for different scenarios in order to evaluate the effect of different parameters on range anxiety. The result that we got were that range anxiety can be decreased with bigger batteries but to get range anxiety just a few times a year you have to use battery sizes which aren’t economical feasible today. Despite the shortcomings of todays electric vehicles there are promising new and future technologies such as better batteries which might help alleviate range anxiety for electric vehicle owner. The conclusion from this study is that in the present fleet of electric vehicles is in need of more charging stations and faster charging to get by the problem with range anxiety and having a chance to compete with gasoline and diesel vehicles.

Pedestrian navigation application based on OpenStreetMap

Scipedia content — Tue, 26 Jan 2021 17:24:53 +0100

This Project is intended to develop a web application in order to make it easier for pedestrians to navigate using a map system named OpenStreetMap OSM. This Open-Source map system provides us a wide range of possibilities when it comes to develop a new application as its maps are totally editable and servers do not have license limitations. The Project aim is to install and configure our own OSM server which is going to give us all the map information such as roads, points of interest, parks, train lines and so on. Another goal is to implement and set up Nominatim and XAPI services which are going to help us when having to make requests to be able to get data from some points or areas on our map. Finally, it has been developed a routing application on OSM map in which we are able to make shortest path queries between 2 points on our map and it is loaded on street map. In order to enhance routing application and take advantage of public transports which OSM serves us, it is going to take into account public transport when distance between these 2 points is too large for a pedestrian.

Assessing the Resilience of Global Sea Routes

Scipedia content — Tue, 26 Jan 2021 17:21:23 +0100

This research develops an attacker-defender model of maritime trading. The defender's problem is represented as a minimum cost, multi-commodity network flow model. System cost is measured in terms of total ton-n.m. in the network. Our network contains the 120 most important ports in the world (by volume of cargo), 35 waypoints at sea, and 416 arcs. Port supply and demand have been estimated from different sources. Interdictions represent manmade disruption of the seaways, such as those in the presence of piracy. An interdicted arc is assumed to incur a penalty equivalent to the additional distance that a ship would need to travel in order to avoid the threat, or a total blockade of the arc in the case of straits and canals. We analyze several scenarios with varying assumptions on the defended arcs and the number of simultaneous interdictions. The most disruptive, single interdiction occurs in the Strait of Gibraltar, increasing cost by almost 25%, followed by the Straits of Bab el Mandeb (20%) and Suez Canal (19%). For two simultaneous interdictions, cost increases to 33%, but decreases to 23%, 8% and 1.5% when we defend three, four or five select straits and canals, respectively. http://archive.org/details/assessingresilie109457344 Lieutenant Colonel, Argentine Air Force

Flexible Demand in Smart Grids - Modeling and Coordination

Scipedia content — Tue, 26 Jan 2021 17:13:49 +0100

The economic analysis of smart grid capabilities needs to incorporate physical boundaries as hard constraints which need to be facilitated by means of flexibility potentials and intelligent dispatching. Due to the distributed nature of demand, economic coordination also needs to be able to facilitate a multitude of individual agents. Questions concerning the modeling and coordination of an active demand side are addressed using tools and techniques from information systems and economics.

Otobüs Öncelikli Yolların Tasarımı Ve İstanbul’ Daki Pilot Otobüs Şeridi Uygulamaları

Scipedia content — Tue, 26 Jan 2021 17:12:22 +0100

Tez (Yüksek Lisans) -- İstanbul Teknik Üniversitesi, Fen Bilimleri Enstitüsü, 2013

Thesis (M.Sc.) -- İstanbul Technical University, Institute of Science and Technology, 2013

Dünya daki tüm ülkelerde, şehir nüfusları her geçen gün artmaktadır. Artan nüfus, trafik sıkışıklığını içinden çıkılmaz bir hale sokmaktadır. Trafik sıkışıklığının çözümü ise toplu taşıma kullanımının arttırılmasıdır. Şehir merkezlerinde trafik sıkışıklığının en kesin çözümü, raylı sistem olmasına rağmen bu sistem oldukça maliyetlidir. Raylı sistemlerin bu dezavantajını ortadan kaldıran otobüs öncelikli yolların kullanımı tüm Dünya? da artmaktadır. Otobüs öncelikli yollar, yalnızca otobüslere ve tahsisli araçlara ayrılmıştır ve mevcut trafikten bağımsız olarak çalışır. Altyapı ve işletme maliyetleri raylı sistemlere oranla oldukça düşüktür. Uygulamayı hayata geçirmek kısa zaman alır. Tasarım eksiksiz yapıldığında ve uygulama yeteri kadar denetlendiğinde, raylı sistemlere yakın derecede trafik sıkışıklığını çözmektedir. Öncelikli otobüs yolları, mevcut trafikteki yükü hafifletip, toplu taşımaya olan katılımı arttırmaktadır. Bu çalışmada, otobüs öncelikli yolların yurtiçinden, yurtdışından, günümüzden ve geçmişten uygulamalar açıklanarak kıyaslamalar yapılmıştır. Yeterli tasarımın nasıl yapılması gerektiği araştırılmıştır. Kavşak ve durak tasarımlar detaylı olarak incelenmiştir. Birinci bölümde, çalışmanın genel anlatımı yapılmış, amacı, yöntemi ve içeriği açıklanmıştır. İkinci bölümde, otobüs öncelikli yolların çeşitleri ve uygulamalardan elde edilen tecrübeler açıklanmıştır. Üçüncü bölümde, ülkemizde daha önceden uygulanmış İstanbul ve Ankara projeleri detaylı olarak incelenmiştir. Dördüncü bölümde, tasarımın geometrisi, kavşak ve durak tasarımları ayrıntılarıyla sunulmuştur. Beşinci bölümde ise çalışma bölgemizdeki uygulama incelenmiş, tasarım kriterlerine, güvenlik tedbirlerine, uygulanabilirliğine göre detaylı bir şekilde sunulmuştur. Altıncı bölümde ise yurtdışındaki uygulamalar ile İstanbul? daki pilot uygulama arasındaki farklar anlatılmıştır. Pilot uygulamada düzenlenmesi gereken eksiklikler detaylı bir biçimde belirtilmiştir. İstanbul? da her geçen gün farklı güzergahta uygulanmaya başlanan otobüs şeridinin pilot uygulaması olan Millet Caddesi projesi detaylı bir şekilde artı ve eksileri ile birlikte incelenmiştir. Daha başarılı olup farklı güzergahlarda da uygulanması için öneriler getirilmiştir. Tasarımından uygulamasına kadar tüm detaylar yurtdışındaki diğer uygulamalar ile kıyaslanmış ve aradaki farklar irdelenmiştir. Toplu taşımaya daha etkili bir biçimde çözüm olabilmesi ve toplu taşımayı daha cazip hale getirebilmesi için öncelikli otobüs yollarında uygulanması gereken tüm bilgiler çalışmanın içerisinde yer almaktadır.

Public transportation is the only solution way of traffic congestion in city centers which have more and more population every passing day. Transportation by private cars, in city centers increases the traffic congestion. Bus transportation and rail systems are the most popular public transportation systems in the world. Rail systems are the most effective system which solve all the traffic congesiton and transportation problems. On the other hand, rail systems are the most expensive systems. Some bus transportation systems are less expensive alternatives to rail systems for solve transportation problems. Bus priority ways are implementing in city centers effectively. Buses increase their average speed without go into the existing traffic on their own ways. Infrastructure and management cost are very low then rail systems. In this research, past and present examples, how to design the busways, which details are important in implementation of bus priority ways are described to use bus priority ways more efficiently. Especially, station and intersection designs are examined sensitively. At first section, general describe of study, purpose of study, method of stufy and content of study are explained. At second section, kids of bus priority ways and experiences of implementations are explained. At third section, Ankara and İstanbul projects which are past implementations in our country are explained with details. At fourth section, the geometry of design, intersection and station designs are described with details. At fifth section, our study location is searched, the other search subjects in this section are; design criteria, safety protection, operationability of implementation. At sixth section, problems are described and results, suggestions are presented. After the pilot Millet Street implementation, every passing day there is a new implementation of bus lanes in Istanbul. In this study, the advantages and lacks of pilot implementation are searched. There are a lot of suggestion for more succesful projects and implementations. All the detail from design to implementation are compared with foreign designs and implementations in big cities of Europe, Asia and America. There all positive and negative details to develop the public transportation in this study. Public transportation in Istanbul comprises a bus network, various rail systems, funiculars, and maritime services to serve the more than 13 million inhabitants of the city spread over an area of 5712 km². The construction of the underground railway in Istanbul began in 1992. The first line (M2) between Taksim and 4th Levent went into service on September 16, 2000. This line is 8.5 km long and has 6 stations, which all look similar but are in different colors. A northern extension from 4th Levent to Atatürk Oto Sanayi station in Maslak (Ayazağa) entered service in 2009, as well as a southern extension from Taksim to Şişhane station in Beyoğlu, near the northern entrance of Tünel. Last northern extension for short term, Hacı Osman was opened in 2011. The rest of the southern section of the metro, which will run to Yenikapı, across the Golden Horn on a bridge and underground through the old city, is also under construction. The southern extension of M2 from Şişhane to Yenikapı over the new Golden Horn Bridge is expected to open in 2013. On the Asian side, 26,5 km long M4 line opened on 17 August 2012 up to Kartal. The line will have a total of 19 stations when the second section as far as Kaynarca opens. A connection to Sabiha Gökçen Airport is proposed. Construction has also begun on the M5 which will link Üskudar, Ümraniye and Çekmeköy on the Asian side. Currently there are 124 Hyundai-Rotem (M2) and 120 CAF (M4) trains in service. A trip along the entire line takes 27 (M2) and 32 (M4) minutes. All lines are operated by Ulaşım A.Ş. (Transport Inc.) which belongs to the Municipality of Istanbul. The bus rapid transit (BRT) system in Istanbul is called Metrobüs. The construction of the Metrobüs BRT line began in 2005. The first line runs between Avcılar and Söğütlüçeşme. This line is 41,5 km long and has 35 stations, which are located on Istanbul s Main Highway, called the D 100. It is currently operated with Mercedes Capacity, Mercedes Citaro, and some Phileas buses. Daily ridership is 715.000 passenger. An extension to Beylikdüzü opened in 2012. The bus fleet has 5356 vehicles (total) built by MAN, Ikarus, Mercedes-Benz, BMC, Phileas, Otokar, Temsa and Güleryüz. Total number of daily ridership is 3621908 passenger and this number consisting %30 of city s total transportation per day in 2012. Since 1985, private owned buses called ÖHO (Özel Halk Otobüsü - Private Public Bus) are allowed to operate under the audit of İETT. There are 2157 private owned public buses, including 144 double-deckers. In 2010, the municipality decided to found a new company called Otobüs A.Ş. (Bus Inc.) for replace old vehicles faster. The fleet of Otobüs A.Ş. consisting 544 vehicles as of December 2012. The vehicles has completely low floor and certified with Euro 5 standards. In developed countries, transportation systems are projected when the population is low and city is less crowded. In Turkey, if there is not a traffic congestion or another problem government doesn?t practice any new implementation or doesn?t design any new projects. Big cities in Europe and America, there are big metro networks. Bus priority systems helps the that network. In Turkey, metro network haven?t finished yet. Bus priority systems function is alternative to inadequate metro network. Istanbul is very old city. It is a big problem to built new transportation networks in a city like this. If the transportation projects design before the city design, the implementation will be more useful.

Yüksek Lisans

M.Sc.

Real-time urban traffic control under saturated traffic conditions

Scipedia content — Tue, 26 Jan 2021 16:58:15 +0100

Περίληψη: Μη διαθέσιμο

Document type: Doctoral thesis

Implementación de un algoritmo metaheurístico para la solución de un problema de programación de transporte terrestre internacional

Scipedia content — Tue, 26 Jan 2021 16:54:57 +0100

Resumen: Este trabajo se enfoca en dar solución a un problema real de planificación de transportes o ruteo de vehículos, definido gracias al aporte de una empresa colombiana del sector de servicios de transporte por carretera. El problema consiste en realizar la programación de operaciones de transporte internacional entre dos países, Colombia y Venezuela, para un horizonte de tiempo con múltiples variantes; entre ellas podemos resaltar: una flota heterogénea de vehículos y tráileres, múltiples depots (clientes), restricciones de ventanas de tiempo en los depots, diversas modalidades de servicio, entre otras. El objetivo es obtener una programación de recursos (vehículos y tráileres) para la atención de la demanda de solicitudes de servicios de transportes en un horizonte de tiempo, minimizando la distancia recorrida en estado vacío de los vehículos para el periodo. La solución se realizó a través de la implementación de la metaheurística Recocido Simulado (SA, Simulated Annealing), la cual se probó iniciando con soluciones factibles generadas por dos algoritmos heurísticos; el primero se basa en la heurística clásica conocida como el vecino más cercano y el segundo genera soluciones de forma aleatoria. Los resultados del Recocido Simulado usando las soluciones generadas con el primer algoritmo, no mostraron una mejora frente a dicha solución inicial, contrario a lo hallado con el uso de las soluciones del segundo método, donde se alcanzó hasta cerca de un 50% de mejora Abstract: This work focuses on finding a solution to a real problem of transport planning or vehicle routing, which has been defined with the collaboration of a Colombian company from the road transport service industry. The problem consists of scheduling the international transport operations between two countries, Colombia and Venezuela, over a time horizon, with multiple variants; such as: a heterogeneous fleet of vehicles and trailers, multiple depots (customers), time windows constraints in the depots, various service modalities, among others. The goal is to schedule the resources (vehicles and trailers) in order to meet the demand for transport service requests on a given time horizon, minimizing the distance traveled by the vehicles while empty. A solution to the problem is given by a Simulated Annealing (SA) Metaheuristic, which was tested by using two types of heuristics to generate the initial feasible solution; the first one is based on the classic “Nearest Neighbor” heuristic, while the second one generates random feasible solutions. The results of the Simulated Annealing using the first algorithm to generate the initial solution did not show any improvement over it, contrary to what was found by using the second method, which obtained up to around 50% of improvemen

Development of Performance Assessment Guidelines for Virginia's Work Zone Transportation Management Plans

Scipedia content — Tue, 26 Jan 2021 16:54:05 +0100

America’s roadways are becoming more congested and more in need of maintenance and repair, management of traffic through work zones is a major issue for state departments of transportation. To aid this, in 2004, the Federal Highway Administration (FHWA) published its Final Rule on Work Zone Safety and Mobility, which mandated that state DOTs develop transportation management plans (TMPs) for all federally-funded roadway construction projects. The Virginia Department of Transportation (VDOT) now requires TMPs for all projects, regardless of funding source. Part of federal and Virginia TMP requirements are to monitor and assess traffic impacts, including a post-construction evaluation of the TMP. Currently, TMPs are not being assessed following individual construction projects, and VDOT does not yet have a formally established process to assess TMP performance throughout its districts and regions. This project developed a set of guidelines to assist VDOT’s work zone personnel and contractors with evaluating TMP performance. The research examines existing literature on work zone evaluation strategies. Thirty state DOTs, as well as personnel within VDOT, were surveyed to explore TMP assessment practices. Finally, two work zone case studies from within the Commonwealth of Virginia were examined. The results of this research effort were used to develop Guidelines for TMP Performance Assessment, with aid and review from a VDOT TMP Performance Assessment Task Group. While these new requirements may add up-front costs to project engineering, VDOT will benefit by having a methodology in place to identify and measure successful strategies to manage safety and mobility impacts from work zones.

Move! Bringing Urban Public Transportation towards Sustainability

Scipedia content — Tue, 26 Jan 2021 16:38:44 +0100

Today’s societal development is not sustainable. The transportation sector has the potential role to be a tremendous lever for sustainability due to its central position in the societal structure as well as for the current unsustainable trends that occur in this system. Recommendations to public transportation providers were made by highlighting the main existing gaps between the current transportation system and an envisioned future transportation system that could exist in a sustainable society. To highlight these gaps, multiple perspectives were considered. These perspectives were enabled by e.g. User Journey Maps at the individual level and a holistic perspective over the broader urban transport system. The premise is that in order to increase use rates of public transportation, there is a need to better assess and address urban travellers' needs when commuting. For providers to have a strategic, stepwise approach and to be able to bring the public transportation system towards sustainability, the authors recommended that public transportation providers prioritize and implement future actions aligned with the three prioritization questions presented at the strategic level of the Framework for Strategic Sustainable Development and by defining a criterion that would emphasize that the users’ needs of importance highlighted in the study are fulfilled.

Kent İçi Çevreyollarında Dinamik Akım Kontrol Yaklaşımlarının Mikro Ölçekli Simülasyonu

Scipedia content — Tue, 26 Jan 2021 16:22:24 +0100

Tez (Yüksek Lisans) -- İstanbul Teknik Üniversitesi, Fen Bilimleri Enstitüsü, 2013

Thesis (M.Sc.) -- İstanbul Technical University, Institute of Science and Technology, 2013

Bu çalışmada, ilk olarak simülasyon ve kontrol stratejilerinin temelini oluşturan trafik akım teorileri makro ölçekli olarak anlatılmıştır. Ardından hidrolik modellerden türetilen trafik değişkenleri tanıtılmış ve bunların aralarındaki ilişkiler gösterilmiştir. Trafik sıkışıklığının ana sebebi olan şok dalgaları analitik olarak incelenmiştir. Daha sonra, bu modellere yapılan ana eleştiriler ve bu modele yapılan iyileştirmeler özetlenmiştir. Çalışmanın üçüncü kısmında makro-mikro-mezo ölçekli simülasyon modelleri anlatılmış ve ardından dördüncü bölümde trafik kontrol yaklaşımları anlatılmıştır. Çalışmanın uygulama kısmında, çalışma sahası tanıtılmıştır. RTMS ten (Remote Traffic Microwave Sensor-Uzaktan Trafik Mikrodalga Algılayıcısı) veri toplama yöntemi anlatılmış ve veri metodolojisi anlatılmıştır. Bununla birlikte, mikro ölçekli simülasyon programı PTV VISSIM tanıtılarak bu programın uzunlamasına ve yanal hareket modelleri anlatılmıştır. Kalibrasyon yöntemi anlatılarak simülasyonun geçerliliği sınanmıştır. Dinamik katılım konreol yaklaşımlarında ALINEA algoritmasının özel iki durumu sınanmış ve değişken hız yönetimi yaklaşımı için dört durum önerilmiştir. Katılım kontrolü için yeşil süre değişimleri, değişken hız yönetimi uygulamaları için hız limitlerinin değişimi ve yoğunluk profilleri çizdirilmiştir. Son olarak toplam seyahat süresi, taşıt başına ortalama gecikme süreleri, taşıt başına ortalama dur kalk sayıları gibi değişik performans ölçütleri için sonuçlar değerlendirilmiştir.

In this thesis, Firstly traffic flow theories are mainly introduced in macroscale which forms the basis of the most of the simulation studies and control strategies. Then relationship between the traffic variables are demonstrated and the flow theories based on the hyraulic model are analyzed and the shockwaves which are the main reason of the traffic congestion shown analytically. Thereafter, main critisism about these models are discussed and improvements are summarized. In the third section of this study macro-micro-mesoscopic simulation models are described and later in the fourth section traffic control approaches are explained. In the application part of this study, the study field is introduced. Data collection methods from RTMS (Remote Traffic Microwave Sensor) are briefly explained and the data methodology is expressed. Moreover, the microsimulation program PTV VISSIM is described and longitudinal and lateral movement models are described. Calibration method is described which demonstrates the validation of the simulation. For dynamic ramp metering approach two cases of ALINEA algorithm are proposed and for VSL approaches four cases are proposed. The fluctuations of the green time for ramp metering and the speed limits for VSL is plotted. Also density profiles for each approach is selected. At the end, results are discussed for various performance indicators such as total travel time, average delay time per vehicle, average number of stops per vehicle, etc.

Yüksek Lisans

M.Sc.

Life Cycle Assessment : of Solelia Greentech’s Photovoltaic BasedCharging Station for Electric Vehicles

Scipedia content — Tue, 26 Jan 2021 16:11:46 +0100

The Swedish company Solelia Greentech AB has developed a charging station forelectric vehicles based on photovoltaic electricity. This report aims to examine theenvironmental impacts of the charging station in terms of greenhouse gas emissionsand energy flows. This has been done by performing a life cycle assessment. Theresults were further investigated through a sensitivity analysis considering recyclingand production site. From these results, the charging station’s greenhouse gas andenergy payback times have been calculated.The report concludes that the charging station has an energy payback time of 3.5years. The greenhouse gas payback time varies from 4 to 117 years depending onassumptions about the electricity in the national electricity grid, which the electricityproduced by the charging station is calculated to substitute. The total energy infusionto the system is 9.4 MWh and the greenhouse gas emissions per delivered kWh fromone charging station during its lifetime are calculated to 0.078 kg CO2eq.

On the Synergies Between an Electronic Waybill and Intelligent Transport Systems Services

Scipedia content — Tue, 26 Jan 2021 16:09:27 +0100

The main purpose of this thesis is to investigate potential synergies between an electronic waybill (e-Waybill) and other Intelligent Transport System (ITS) services. An e-Waybill service, as presented in this thesis, should be able to perform the functions of a paper waybill (which is an important transport document and contains essential information about a consignment) and it should contain at least the information specified in a paper waybill. To investigate synergies between the e-Waybill solutions and ITS services, we present 5 conceptual e-Waybill solutions that differ in where the e-Waybill information is stored, read, and written. These solutions are further investigated for functional and technical requirements (non-functional requirements), which can potentially impose constraints on a potential system that should implement the e-Waybill service. A set of 20 ITS services are considered for synergy analysis in this thesis. These services are mainly for road transport, however most of them are relevant to be considered for utilization in other modes of transport as well. For information synergy analysis, the e-Waybill solutions are assessed based on their synergies with ITS services. For different ITS services, the required input information entities are identified; and if at least one information entity can be provided by an e-Waybill at the right location we regard it to be a synergy. The result from our synergy analysis may support the choice of practical e-Waybill systems, which has the possibility to provide high synergy with ITS services. This may lead to a higher utilization of ITS services and more sustainable transport, e.g., in terms of reduced congestion and emissions. Additionally, a service design method has been proposed for supporting the process of designing new ITS services, which primarily utilizes on functional synergies with already existing ITS services. In order to illustrate the usage of the suggested method, we have applied it for designing a new ITS service, i.e., the Liability Intelligent Transport System (LITS) service. The purpose of the LITS service is to support the process of identifying when, where, and by whom a consignment has been damaged and who was responsible when the consignment was damaged.

Cross-Layer optimization in a satellite communication network

Scipedia content — Tue, 26 Jan 2021 15:57:38 +0100

This thesis aims to improve a satellite communication network which carries both data streams and Voice over IP (VoIP) communication sessions with resource reservation. The resource reservations are made using the standard protocols for Traffic Engineering: MPLS-TE and RSVP-TE. The goal of this thesis project is to optimize the number of concurrent VoIP calls that can be made, in order to use the available bandwidth while maintaining a guaranteed Quality of Service (QoS) level, which is not possible in the existing system. This thesis proposes and evaluates a solution to this optimization problem in the specific context of a satellite modem system that was developed by Thales Communications. This optimization improves the system's ability to carry VoIP communications through better use of the available transmission resources. A solution to this problem would also increase the exibility in bandwidth allocation within the modem system, and could provide a framework for future development. The proposed solution allows all of the reservable bandwidth to be used. The amount of reservable bandwidth must be at least a little lower than the channel's available bandwidth in order to avoid congestion. Some areas of future work are proposed. Detta projekt har försökt förbättra ett datornätverk bestående av satelliter som används till både data och Voice over IP (VoIP) kommunikation. VoIP använder sig av resursreservation som bestäms av standardprotokollen för Traffic Engineering, MPLS-TE och RSVP-TE. Målet är att optimera antalet samtidiga VoIP samtal så att det mesta av den befintliga bandbredden kan utnyttjas samtidigt som Quality of Service (QoS) kan garanteras. Detta är omöjligt i det befintliga systemet. Projektet föreslår en lösning för problemet med modemet som utvecklas av Thales Communications och utvärderar därefter lösningen. Dessa optimeringar förbättrar systemets förmåga att driva VoIP kommunikationer genom att bättre använda de befintliga resurserna. En lösning för det här problemet skulle höja systemets flexibilitet och kunna användas som underlag för kommande utvecklingar. Tack vare lösningen kan hela utsedda bandbredden reserveras. Antalet bandbredd som kan reserveras måsta vara minst lite lågre än total befintling bandbredd för att undvika överbelastning. även några möjliga ideer för vidare undersökning föreslås. Ce projet a pour but d'améliorer un réseau de communication par satellite utilisé pour transporter des flux de données ainsi que des sessions de communication Voix sur IP (VoIP) avec réservation de ressources. Les réservations sont prises en charge par les protocoles standard de Traffic Engineering que sont MPLS-TE et RSVP-TE. L'objectif de ce projet est d'optimiser le nombre d'appels VoIP pouvant être passés en parallèle afin d'utiliser autant de bande passante que possible tout en offrant un niveau de Qualité de Service (QoS) garanti, chose impossible dans le système actuel. Ce rapport propose et évalue une solution à ce problème d'optimisation dans le contexte spécifique du modem satellite développé par Thales Communications. Ces optimisations amélioreraient la capacité du système à transporter des communications VoIP grâce à une meilleure utilisation des ressources disponibles pour la transmission. Une solution à ce problème rendrait aussi l'allocation de ressources plus flexible au sein du système, et pourrait fournir une base à de futurs développements. La solution proposée permet l'utilisation de toute la bande passante réservable. La quantité réservable doit être un peu inférieure à la bande passante totale disponible afin d'éviter la congestion. Les résultats de ces évaluations sont exposés. Enfin, ce rapport propose de futurs développements possibles.

Lugvaartskedulering met behulp van intelligente agente.

Scipedia content — Tue, 26 Jan 2021 14:27:55 +0100

M.Sc. This thesis investigates how intelligent agents can be used to solve airline scheduling problems. It is divided into three parts. The first states what airline scheduling consists of; the second discusses the results of a literature study; and the third consists of solutions to the problem. Airline scheduling consists of three major activities viz. market-driven flight generation, crew assignment and operational problem management. The market schedulers first create a flight set based on a forecast of passenger numbers and passenger preferences. The crew schedulers attempt to crew the flights generated by the market schedulers (subject to safety and rest regulations). The operational schedulers maintain the flights from seven days prior to the day of operation to one day after the end of the flight. Finding a global solution to this three-phase operation is the airline scheduling problem. An agent-based solution to the airline scheduling problem was the focus of this thesis. Agents encapsulate many useful artificial intelligence solution strategies. For the proposed solution to the market driven scheduling problem a distributed negotiation scheme using agents was used. A routing and an assignment agent were defined to assist the crew scheduler. Finally an operational scheduling agent was defined to solve the operational scheduling problem. The routing and assignment agents make use of FIFOqueues and genetic algorithms. The operational scheduling agent makes use of a traditional expert system combined with a learning algorithm to give it more flexibility. A prototype, developed in Java, was used to demonstrate how agents could solve the market driven scheduling problem. This distributed negotiation scheme was implemented on Sun SPARC workstations running the Solaris operating system. A prototype developed in Delphi was also developed to show how learning algorithms could be applied to the scheduling environment.

Estudi de les prestacions dels protocols d'encaminament geogràfics i topològics per a Vehicular ad-hoc Networks

Scipedia content — Tue, 26 Jan 2021 14:15:47 +0100

Estudi i avaluació de les característiques i les prestacions de les xarxes de vehicles (VANETs) en entorns urbans.

Remote Tower Centre - Configuration and Planning of the Remote Tower Modules

Scipedia content — Tue, 26 Jan 2021 14:13:23 +0100

Today, many small aerodromes have a hard time surviving economically, and amongst the largest cost is air traffic control. Airlines are cutting costs where they can, and many times this affects the aerodromes as well, e.g. when airlines decide to park remotely instead of at the gate. The project called Remotely Operated Towers, initiated by SESAR and run by Saab and LFV, is aiming to address this problem. The project revolves around remotely providing ATS to aerodromes where it is deemed suitable. A big challenge in this project is how to assign aerodromes to remote tower modules in the remote control centre. There are many ways to do this, but there is only a few ways to do it to achieve the least amount of modules. This thesis aims to find an optimal solution to the challenge mentioned above. The thesis resulted in a model where the user can provide the input of choice, i.e. aerodromes with associated ATS operating hours and movements, for a specific period – and receive the assignment schedule for the modules, saying exactly which aerodrome are to be controlled by which module at what time.

Integration of Design for Environment in the vehicle manufacturing industry in Sweden : Focus on practices and tools

Scipedia content — Tue, 26 Jan 2021 13:55:25 +0100

Design for Environment (DfE) promotes the systematic consideration of environmental aspects during product design and development. Despite the maturity of concepts and tools in literature, efficient implementation in industries is reported to be low. A need to bridge this gap is identified with studies that look on DfE practices as well as the use and potential of DfE tools. This thesis is part of a research project that investigates DfE practices and the use of tools during vehicle design and development. The aim is to investigate the ways that environmental constraints can be efficiently integrated into product development processes thus assist in improving the environmental performance of products from a life cycle perspective. The scope of the study includes four vehicle manufacturing companies in Sweden. The development and utilization of tools has been also investigated aiming to increase the opportunities for effective use within this product category. Case study methodology, research interviews and literature reviews constitute the research strategy followed in this work. The empirical results presented in this thesis indicated that vehicle manufacturing companies in Sweden are continually working to improve the environmental performance of their products and meet legal and costumer demands. Despite similarities regarding the type of environmental requirements considered, the companies studied have adopted different ways to identify and integrate environmental requirements into their product development process and use DfE tools to different extents. Such variations reflect differences in the success and maturity levels of the DfE practices adopted. A need for increased and more systematic use of tools is identified for all studied companies and especially for analytical tools. Results from the literature review showed that a variety of tools are available that have the potential to support vehicle design processes. However, only a few cover a broad set of aspects identified to be relevant from a vehicle design perspective. For DfE tools to become effective and be used during product development, they need to cover aspects that are relevant for the company and product designers. A need towards the development of tools that assist vehicle or product designers in general, to make informed and comprehensive choices based on a variety of requirements associated to the product, is identified. Coupling Materials Environmental Analysis - Environmental Effec

Methodology of propulsion system design of electric vehicles.

Scipedia content — Tue, 26 Jan 2021 13:40:29 +0100

O interesse por veículos elétricos voltou a crescer nos últimos anos, principalmente, devido às questões ambientais e de eficiência energética. Aliado ao desenvolvimento de fontes e acumuladores de energia com densidades de energia e potência maiores que viabilizam a utilização de veículos elétricos em substituição parcial dos veículos com motores a combustão interna, já surgem comercialmente no mercado alguns modelos de veículos elétricos. Neste contexto, também cresce a necessidade de recursos humanos capacitados e ferramentas auxiliares para o dimensionamento dos componentes dessa nova geração de veículos automotores. Este trabalho apresenta uma metodologia simples e direta de dimensionamento do sistema de tração para veículos elétricos autônomos, bem como os resultados de uma aplicação prática da utilização desta metodologia no desenvolvimento de veículos elétricos fora de estrada para transporte de pessoas e de material. A comparação entre os resultados práticos obtidos com os cálculos realizados mostra que a metodologia, com o equacionamento completo e abrangente apresentado, fornece resultados com excelente exatidão. The interest in electric vehicles is growing again in recent years, mainly due to environmental concerns and energy efficiency issues. Combined with the development of energy storage devices with higher power and energy densities that enable the use of electric vehicles, some models already appear commercially in the market replacing vehicles with internal combustion engines in specific applications. In this context, it also increases the need for trained human resources and auxiliary tools for designing the components of this new vehicles generation. This dissertation presents a simple and direct methodology of propulsion system design for autonomous electric vehicles as well as the results of a practical application of using this methodology in the development of off-road electric vehicles for people and material transport. The comparison between the practical results obtained with the calculations shows that the methodology, with the complete and comprehensive equations presented, provides results with excellent accuracy.

Sustainable Transport Development for Accra: Critiquing Ideologies and Unraveling Priorities

Scipedia content — Tue, 26 Jan 2021 13:39:46 +0100

It is questionable whether decentralization or economic liberalization policies form good foundations for good governance in a developing country. Ghana’s first National Transport Policy was drafted in 2008. A prominent theme in this policy document is ensuring sustainable development of urban public transportation, through, among other things, good governance. The document, however, is built within the contextual frameworks of Ghana’s Poverty Strategy Papers, which espouse decentralization and economic liberalization policies. It is argued that these policies are incompatible with the transport policy agenda for sustainable development as they are not fertile ground for breeding good governance. However they are conducive to ensuring the premier priority within Accra’s public transportation system is met – which is maintaining employment and thus upholding livelihoods.

Study of Personnel Attrition and Revocation within U.S. Marine Corps Air Traffic Control Specialties

Scipedia content — Tue, 26 Jan 2021 13:33:03 +0100

This thesis evaluates U.S. Marine Corps Air Traffic Control (MATC) military occupational specialties (MOSs) to determine methods of reducing personnel attrition from the MATC Basic Course and revocation from operational forces. The author analyzes Marine Corps personnel data obtained from the Total Force Data Warehouse and Headquarters Marine Corps. The range of the data analyzed covers a period from fiscal years 1999 through 2008, including 965 MATC Marines. Multivariate regression models are estimated to determine the effects of AFQT score, ASVAB composite scores, demographics, and other measures of performance on the likelihood of personnel attrition and revocation. Results indicate that changing selection criteria for AFQT score or ASVAB composite scores is not warranted. It is recommended that current selection criteria be augmented with improved medical screening at Military Entrance Processing Stations (MEPS) and recruit depots, to include non-cognitive testing, such as Navy Computer Adaptive Personality Scales (NCAPS), during recruitment. It is also recommended that an economic analysis be conducted comparing the cost of personnel losses during training with the cost of losses due to revocation. http://archive.org/details/studyofpersonnel109456830 Major, United States Marine Cor

QoS-Constrained Traffic Engineering for Interference-affected Wireless Mesh Networks with Network Coding

Scipedia content — Tue, 26 Jan 2021 13:23:46 +0100

This thesis focuses on the QoS-constrained Traffic Engineering (TE) of Wireless Mesh Networks (WMNs) affected by Multiple Access Interference (MAI). The goal is to develop a tool for the optimization of network/physical resource allocation that enable to design WMNs supporting multicast multimedia sessions with different Quality of Service (QoS) requirements when intra-session Network Coding (NC), besides routing, can be performed at the network nodes. A wide-applicability integrated framework is proposed, that allows to jointly optimize session utilities, flow control, QoS differentiation, intra-session network coding, Media Access Control (MAC) design and power control. To cope with the nonconvex nature of the resulting cross-layer optimization problem, this thesis proposes a two-level decomposition that provides the means to attain the optimal solution through suitably designed convex subproblems. Sufficient conditions for the feasibility of the primary (nonconvex) problem and for the equivalence to its related (convex) version are derived. Furthermore, a general procedure to devise simple polyhedral outer-bounds of the capacity region, which will be shown to have a key role in the decomposition, has been developed. Algorithmic implementation of the two-level decomposition is discussed in both centralized and distributed approaches. Moreover, the asynchronous, iterative Distributed Resource Allocation Algorithm (DRAA), that quickly self-adapts to network time-evolutions (e.g., node failures and/or fading fluctuations), is developed. Numerical results that delve into the potential of both the proposed solution and the resource allocation algorithm, are provided. In detail, the two-level decomposition will be tested in unicast, multicast and multisource scenarios so as to show the performance gain achievable by the joint optimization with respect to the conventional solutions.

Investigation of Runway Incursion

Scipedia content — Tue, 26 Jan 2021 13:19:51 +0100

Runway incursions (RWYI) are a daily phenomenon in the world and is a threat to safety. The severity of a RWYI can be high and it is a problem that is subject to improvements. The purpose of this report is to present the findings after an investigation of RWYI in general and what is being done to prevent it in Sweden. The main focus is to present the problem from an air traffic controller (ATCO) and pilot perspective. However, we are also presenting all the different stakeholders involved in the problem followed with associated risks and means to prevent a RWYI from happening. We also present technical aids and working methodology used today in air traffic control towers in Sweden and in addition some technology implemented abroad. Some suggested improvements that the stakeholders can take into consideration when developing their work to reduce the risk for a RWYI is also presented. The method used during the investigation has mainly been literature studies, interviews with different stakeholders and study visits to Bromma tower, Arlanda tower and SAAB/Linköping tower. We have found that the pilots and vehicle drivers are the most contributing stakeholders to a RWYI in Sweden. The investigation also shows that ATCOs and pilots share some opinions regarding risks but also improvements. Both ATCOs and pilots agree that weather with bad visibility, as well as darkness, is increasing the risk for an incident or accident to happen. Furthermore, complacency, fatigue and tiredness are also risks that are shared between ATCOs and pilots. We have also found that airports have different means to prevent a RWYI. At Arlanda, the ATC system is well developed with electronic equipment and stop bars at the taxiways, which is not the case for either Bromma or SAAB/Linköping airport. Even pilots in different airlines operate differently when about to enter a runway and there is no standard operating procedure (SOP) developed in all companies. Some of the suggested improvements are to implement stop-bars on every airport and that it should be mandatory to equip vehicles operating on the maneuvering area with maps.

Identification des paramètres d’un modèle TGV

Scipedia content — Tue, 26 Jan 2021 13:15:41 +0100

This work investigates the applicability of identification methods to the suspension parameters of a TGV multi-body model. The aim is to adjust the model to the real system by estimating the suspension parameters from measured vehicle response data. Due to the nonlinear behavior of the system the time-domain based model updating has been chosen. It requires the definition and minimization of a misfit function in the time domain describing the distance between model and measurement. The fastest convergence is obtained by the use of gradient methods requiring the calculation of the derivatives of the misfit function relative to every parameter. Since the calculation from finite differences is time consuming and less accurate the gradients are calculated from the adjoint method. The application to a simplified bogie model with known mathematical description allows the identification of its suspension parameters. The presence of local minima in the misfit function of the TGV model requires the use of global optimization methods. The simulated annealing and the genetic algorithm method give important reductions of the misfit function and improved parameter estimations. In following work this information could be used for further applications like the condition monitoring.; Ce travail étudie l’applicabilité des méthodes d’identification aux paramètres de la suspension d’un modèle multi-corps du TGV. L’objectif est de caler le modèle par rapport au système réel par une estimation des paramètres de la suspension en utilisant la réponse du véhicule mesuré. A cause du comportement nonlinéaire du système la méthode temporelle de recalage a été choisie. Elle nécessite la définition et minimisation d’une fonction coût qui décrit la distance entre le modèle et la mesure. La convergence la plus rapide est obtenue avec des méthodes gradient qui demandent le calcul des dérivés de la fonction coût par rapport á chaque paramètre de la suspension. Comme le calcul par des différences finis est coûteux et moins précis la méthode adjoint a été implémentée. L’application à un modèle simplifié d’un bogie avec une description mathématique connue permet d’identifier les paramètres de la suspension. La présence des minima locaux dans la fonction coût du modèle TGV nécessite l’utilisation des méthodes globales. Le recuit simulé et l’algorithme génétique donnent des réductions importantes de la fonction coût et des estimations pour les paramètres du modèle TGV. Dans des travaux ultérieurs, ces informations pourraient être utilisées pour d’autre application comme le « condition monitoring ».

Impacts of ship-induced waves on benthic macroinvertebrates

Scipedia content — Tue, 26 Jan 2021 13:10:02 +0100

Schifffahrt stellt weltweit eine der wichtigsten Nutzungen der Flüsse und Seen dar, die zukünftig weiter zu nimmt. Sie schädigt Ufer durch Wellenschlag erheblich. Die Effekte von Schiffswellen auf benthische Wirbellose sind aber bisher kaum bekannt, obwohl diese eine zentrale Rolle im litoralen Nahrungsnetz spielen. Daher untersuchte ich 1) die direkten Effekte von Schiffswellen auf benthische Wirbellose, 2) die resultierenden Auswirkungen auf trophische Interaktionen und 3) das Wachstum und die Fitness von Wirbellosen, sowie 4) die langfristigen Änderungen der litoralen Wirbellosenzönosen. Labor- und Feldversuche zeigten, dass mit zunehmender wellengenerierter Sohlschubspannung mehr Individuen verdriftet wurden. Die Verdriftung wurde jedoch durch eine hohe strukturelle Habitatkomplexität gemindert, da diese die Wellenenergie stärker dissipierte und den Wirbellosen bessere Festhaltemöglichkeiten bot. Die Verdriftung der Wirbellosen bewirkte ein höheres Prädationsrisiko durch spindelförmige Fische, während hochrückige Fische die Ingestion bei Wellenexposition reduzierten. Wellenschlag verringerte auch das Wachstum und die Fitness nativer Wirbellosenarten, indem die Ingestion verringert oder der Energieverbrauch erhöht wurde, wohingegen Neozoen nicht beeinträchtigt wurden. Der kumulative Effekt von Schiffswellen veränderte die Artenzusammensetzung benthischer Zönosen sehr. Die Abundanz nativer Wirbelloser und die Artenzahl waren an exponierten Ufern geringer, während die Abundanz invasiver Arten zunahm. Folglich beeinträchtigen Schiffswellen benthische Wirbellose auf der Ebene der Individuen, Arten, Zönosen, sowie tropischer Interaktionen, und können so die ökologische Struktur und Funktion des gesamten Litorals beeinflussen. Durch Schutz komplexer Habitate wie Wurzeln und dichte Schilfbestände, sowie durch Wellenschlagsreduzierung durch größere Mindestabstände zum Ufer und angepasste Fahrtgeschwindigkeit, können die Auswirkungen von Schiffswellen gemindert werden. Inland navigation is a major human use of rivers and lakes worldwide which is expected to increase in the future. It significantly affects shore habitats by ship-induced waves. In contrast to the importance of such pressures, the effects of these hydrodynamic disturbances on benthic invertebrates in the littoral zones are poorly understood, even that invertebrates are a central element of littoral food webs. Hence, I investigated 1) the direct and immediate effects of ship-waves on benthic invertebrates, 2) their subsequent effects on trophic interactions and 3) on the growth and fitness of invertebrates, and finally 4) the long-term effects on the community composition. Laboratory and field experiments showed increasing detachment of invertebrates with higher wave-induced shear stress. Detachment was significantly mitigated by higher structural complexity of the habitats, as complex habitats dissipate wave energy and provide better fixing possibilities. Moreover dislodgement of invertebrates led to a higher risk of being preyed upon by fusiform fish, while deep bodied fish reduced feeding under waves. Waves also reduced growth and fitness of native invertebrates via reduced feeding or increased energy costs, while non-native invertebrates were not affected. The cumulative impact of ship-waves alters the community composition of benthic invertebrates. The abundance of native invertebrates and total species richness was lower at exposed sites, while non-native invertebrates increased in abundance. Thus, ship-waves affect benthic invertebrates on the individual, species, and community levels, as well as the interaction of trophic levels, and hence will alter the ecological structure and function of whole littoral zones. Adverse effects of ship-waves may be mitigated by protecting structural complex habitats such as tree roots and dense reed belts, and by minimizing wave generation by increasing minimum sailing distance to shore or by adjusting vessel speed.

Model optimalnega portfelja projektov izgradnje železniške infrastruktur na V. in X. koridorju

Scipedia content — Mon, 25 Jan 2021 20:20:40 +0100

The construction of railway infrastructure should be dealt with as a national strategic developmental programme, which due to technical, geographical, logistical, and other requirements is carried out through a number of projects and represents a complex multiple project operation for investors, contractors, and other influential players. The national strategic developmental programme for the construction of the railway infrastructure is connected through programmes in neighbouring countries and EU member states to Trans-European Networks (TEN) that strategically regulate construction within the community. In the Republic of Slovenia, the construction of railway infrastructure within TEN programmes is carried out on the pan-European traffic corridors V and X within individual projects for the construction of sections and a number of supporting projects. Technical requirements, deadlines, and other TEN requirements as well as national strategic requirements and financial possibilities of the state represent basic criteria that should be taken into consideration in setting up a strategic project plan, with optimal project classification achieved through the implementation project portfolio. The current article utilised the method of multiple-criteria decision analysis to prepare the portfolio, taking into account macroeconomic and infrastructural criteria. Consequently, the results represent the basis for the preparation of an optimal financial plan with regard to financing possibilities of the Republic of Slovenia and the European Union. The article also summarised the research results regarding the formation of the project implementation process of the TEN-T network construction in the Republic of Slovenia. Izgradnjo železniške infrastrukture je potrebno obravnavati kot nacionalni strateški razvojni program, ki se zaradi tehničnih, geografskih, logističnih in drugih zahtev izvaja z več projekti in pomeni za investitorje, izvajalce in druge vplivne dejavnike kompleksno multiprojektno poslovanje. Nacionalni strateški razvojni program izgradnje železniške infrastrukture se navezuje na programe sosednjih držav in v primeru držav, ki so članice EU, na Trans-evropsko transportno omrežje (TEN), ki strateško ureja to izgradnjo v okviru te skupnosti. V R Sloveniji se izgradnja železniške infrastrukture v okviru TEN izvaja na V. in X. pan-evropskima prometnima koridorjema s posameznimi projekti izgradnje odsekov in vrsto podpirajočih projektov. Tehnične, rokovne in druge zahteve TEN, nacionalne strateške zahteve ter finančne možnosti države so osrednji kriteriji, ki se morajo upoštevati pri pripravi strateškega projektnega plana z optimalnim razvrščanjem projektov, kar daje izvedbeni protfelj projektov. Za oblikovanje portfelja je bila uporabljena metoda večkriterijskega razvrščanja, kjer so bili upoštevani makroekonomski in infrastrukturni kriteriji, hkrati pa je osnova za izdelavo finančnega plana, ki je optimalen glede na možnosti financiranja s strani R Slovenije in EU. Članek podaja tudi izsledke raziskave oblikovanja procesa projektnega izvajanja izgradnje TEN-T omrežja v R Sloveniji.

Distribution Integrity Management Plant (DIMP)

Scipedia content — Mon, 25 Jan 2021 20:18:11 +0100

This document is the distribution integrity management plan (Plan) for the Los Alamos National Laboratory (LANL) Natural Gas Distribution System. This Plan meets the requirements of 49 CFR Part 192, Subpart P Distribution Integrity Management Programs (DIMP) for the LANL Natural Gas Distribution System. This Plan was developed by reviewing records and interviewing LANL personnel. The records consist of the design, construction, operation and maintenance for the LANL Natural Gas Distribution System. The records system for the LANL Natural Gas Distribution System is limited, so the majority of information is based on the judgment of LANL employees; the maintenance crew, the Corrosion Specialist and the Utilities and Infrastructure (UI) Civil Team Leader. The records used in this report are: Pipeline and Hazardous Materials Safety Administration (PHMSA) 7100.1-1, Report of Main and Service Line Inspection, Natural Gas Leak Survey, Gas Leak Response Report, Gas Leak and Repair Report, and Pipe-to-Soil Recordings. The specific elements of knowledge of the infrastructure used to evaluate each threat and prioritize risks are listed in Sections 6 and 7, Threat Evaluation and Risk Prioritization respectively. This Plan addresses additional information needed and a method for gaining that data over time through normal activities. The processes usedmore » for the initial assessment of Threat Evaluation and Risk Prioritization are the methods found in the Simple, Handy Risk-based Integrity Management Plan (SHRIMP{trademark}) software package developed by the American Pipeline and Gas Agency (APGA) Security and Integrity Foundation (SIF). SHRIMP{trademark} uses an index model developed by the consultants and advisors of the SIF. Threat assessment is performed using questions developed by the Gas Piping Technology Company (GPTC) as modified and added to by the SHRIMP{trademark} advisors. This Plan is required to be reviewed every 5 years to be continually refined and improved. Records for all piping system installed after the effective date of this Plan will be captured and retained in the UI records documentation system. Primary Utility Asbuilts are maintained by Utilities Mapping (UMAP) and additional records are maintained on the N drive. Engineering Change Notices (ECNs) are stored on the N drive under configuration management and kept up by Utilities and Infrastructure Division Office (UI-DO). Records include, at a minimum, the location where new piping and appurtenances are installed and the material of which they are constructed.« le

Model trajnostne rasti in razvoja žičniškega prometnega sistema v Sloveniji

Scipedia content — Mon, 25 Jan 2021 20:00:14 +0100

The cableway transport system is very important for the Slovenian tourist economy. Within the Slovene transport system, the cableway transport subsystem has a specific role because it allows and ensures access to regions which are difficult to access or completely inaccessible by other transport subsystems owing to the configuration of the area. The quality and development of transport services are directly linked to the introduction of new cableways. New technical achievements, which are nowadays used in cableways, all provide greater capacity and higher speed of cableways, which, however, results in their higher maintenance and exploitation costs. The cableway transport system is being developed in Slovenia, but not on principles of sustainable development. This paper presents a model of sustainable growth and development of the cableway transport system in Slovenia based on which it is possible to determine assumptions for future growth so that the Slovene cableway transport system would approach standards of such highly developed systems. The new model includes ten essential elements of this system for which growth rates were calculated. Žičniški prometni sistem ima v slovenskem turističnem gospodarstvu važno vlogo. V okviru prometnega sistema ima kot prometni podsistem specifično vlogo, saj nudi dostopnosti do krajev, ki so zaradi geografskih značilnosti težko dostopni ali nedostopni z drugimi prometnimi podsistemi. Novi tehnični dosežki, ki se uporabljajo na žičniških napravah omogočajo vse večje hitrosti in kapacitete žičniških naprav, vendar je zaradi vedno več potrebno vlagat v vzdrževanje in obratovanje žičniških naprav Žičniški prometni sistem se v Sloveniji razvija, ampak na načelih trajnostnega razvoja. V tem članku je predstavljen model trajnostne rasti in razvoja žičniškega prometnega sistema v Sloveniji, na osnovi katerega je mogoče določiti predpostavke za bodoči trajnostni razvoj, da bi se slovenski žičniški promet približal standardom visoko razvitih žičniških sistemov. Novi model zajema 10 bistvenih elementov tega sistema, znotraj katerih so podane direktne in indirektne stopnje rasti razvoja.

Simulation of crossroad traffic

Scipedia content — Mon, 25 Jan 2021 19:59:54 +0100

It is difficult to find the right tool for making traffic regime models because so many different situations are involved. Simulink has proved to be one of the best. The paper shows the design and the use of components and models in the program Matlab/SIMULINK. It presents the simulation results for the model of a traffic light controlled crossroad and indicates the possibilities for the study of traffic optimisation in junctions. Izjemna množica različnih situacij v prometu posledično povzroča tudi probleme pri iskanju primernega orodja za simuliranje različnih prometnih režimov. Izkazalo se je, da je SIMULINK eden od najboljših orodij za izvajanje tovrstnih simulacij. Članek prikazuje, kako oblikovati in uporabljati posamezne komponente in modele v programu Matlab/SIMULINK. Predstavljeni so rezultati izvedene simulacije na primeru semaforiziranega križanja prometnih tokov. Ob tem so zaznane posamezne možnosti za nadaljnjo optimizacijo semaforskih nastavitev.

Smart Grids and Electric Vehicles

Scipedia content — Mon, 25 Jan 2021 19:56:54 +0100

Electric vehicles (EVs) could play a central role in decarbonising road transport. But this new type of electricity load will need careful management. Although electricity needs for EVs are likely to remain small relative to overall load in most regions for many years to come, they could have a much bigger impact on peak load as motorists seek to recharge their batteries during the evening. Electricity suppliers will need to anticipate the long-term investments that will be needed to respond to this emerging trend. (...)

Reducing Greenhouse Gas Emissions in a Cost Effective Way in Switzerland

Scipedia content — Mon, 25 Jan 2021 19:54:33 +0100

Switzerland has low greenhouse gas emissions per capita as compared to other countries, which reflects the strong reliance on energy sources emitting few greenhouse gas emissions, especially in electricity generation, and little heavy industry. Greenhouse gas emissions have remained almost the same since 1990, as emission reductions in the residential and industrial sector were offset by increases from the transport sector. It is estimated that, in aggregate, marginal abatement costs are relatively high in Switzerland and meeting the 2020 target of a 20% emission reduction below the 1990 level will necessitate more cost effective policies. In particular, more needs to be done in the road transport sector, the domestic sector with the largest potential for emission reductions at relatively low cost. The incentive for energy saving renovations in rented dwellings could be raised by a better design of existing policies. And the policies in the industrial sector could be made more effective with the transition towards linking the Swiss and the EU emission trading systems. Reduire les emissions de gaz a effet de serre pour un cout raisonnable en Suisse Comparee a d’autres pays, la Suisse emet peu de gaz a effet de serre par habitant, car elle recourt en grande partie a des sources d’energie qui n’en produisent pas beaucoup, notamment dans le secteur de l’electricite, et son industrie lourde est modeste. Ces emissions sont a peu pres stables depuis 1990, leur diminution dans les secteurs residentiel et industriel ayant ete compensee par une hausse dans celui des transports. D’apres les estimations, les couts marginaux de la reduction des emissions sont dans l’ensemble relativement eleves en Suisse et des mesures plus efficaces par rapport a leur cout seront necessaires pour atteindre l’objectif fixe d’ici 2020, a savoir un retour a 20 % en dessous du niveau de 1990. Il faut en particulier accentuer l’effort dans le secteur des transports routiers, lequel presente le potentiel le plus eleve de reduction des emissions a un cout relativement bas. L’incitation en faveur des travaux d’economie d’energie dans les logements en location pourrait etre renforcee moyennant une meilleure conception des mesures existantes. L’action menee dans le secteur industriel pourrait gagner en efficacite moyennant le couplage progressif des systemes suisse et communautaire d’echanges de credits d’emission.

Machinist Pipeline Program

Scipedia content — Mon, 25 Jan 2021 19:48:06 +0100

Road Freight in Central America : Five Explanations to High Costs of Service Provision

Scipedia content — Mon, 25 Jan 2021 19:46:19 +0100

n efficient system to transport goods domestically and internationally is a key element of the logistics chain. Road freight transport has a direct impact on poverty as it employs millions of people and generates a significant portion of Gross Domestic Product, or GDP, especially in low and middle-income countries. Trucking is the primary form of transportation for domestic, trans-border, and international cargo, in Central America. Road freight transport is now vital to production, distribution, and mobilization, driving economic, social, and environmental progress. In short, trucking is the backbone of economies around the world. In the past 20 years, the industry has advanced as technology has improved communication, management, productivity, including vehicle efficiency. Their objective in doing so is to expand markets, generate wealth on the basis of efficient specialization, introduce competition, and lower costs for production, distribution, services, and research and development. When road freight transport services are efficient, they support these objectives; when they are not they act as nontariff barriers to trade, creating delays, raising costs, worsening congestion and pollution. Such barriers prolong and destabilize delivery schedules, hinder 'just in time' inventory management and industrial processes, and impede the efficient combination of factors of production.

Kolaborativno vedenje kot spodbujevalni dejavnik integracije logistične in marketinške funkcije

Scipedia content — Mon, 25 Jan 2021 19:37:37 +0100

Collaborative behaviour and various aspects of comparing collaboration with coordination and cooperation present the basis for more detailed assumptions concerning the importance of integrating logistic function with the marketing function. The collaborative behaviour dimension of inter-functional integration presents a system of mutual visions, decision-making and collective responsibility to provide results, services or a product. Logisticians often define integration within the framework of the supply chain, yet they neglect the internal integration or the integration between individual departments or functions in a company. Defining internal integration and its level as well as the connection with the level of collaborative behaviour is the basis of the research part of this paper. The quantitative research part studies whether and to what extent collaborative behaviour influences the level of internal integration between logistic and marketing functions. The research is based on a quantitative analysis of results of the survey that was conducted in Slovene retail companies. Kolaborativno vedenje kot osnova tega pojava in različni vidiki vzporejanja kolaboracije s koordinacijo in kooperacijo predstavljajo osnovo za ožje ugotovitve v povezavi s pomenom integracije logistične funkcije z marketinško funkcijo. Kolaborativno vedenjska dimenzija med-funkcijske integracije predstavlja sistem skupnih vizij, skupnega odločanja in kolektivno odgovornost za končni izid, storitev ali proizvod. Logisti pogosto opredeljujejo integracijo v okviru oskrbne verige, pozabijo pa na notranjo integracijo oz. integracijo med posameznimi oddelki oz. funkcijami v podjetju. Opredelitev notranje integracije in njenega nivoja ter povezava z nivojem kolaborativnega vedenja je osnova raziskovalnemu delu tega članka. V kvantitativnem raziskovalnem delu se preučuje ali in kako nivo kolaborativnega vedenja vpliva na nivo notranje integracije med logistično in marketinško funkcijo. Raziskovanje temelji na kvantitativni analizi rezultatov vprašalnika, ki je bil izveden v slovenskih trgovskih podjetjih.

Improving city transport with the objective to reduce CO2 emissions

Scipedia content — Mon, 25 Jan 2021 19:32:34 +0100

In the past few years traffic volume is increasing. As a consequence, negative external traffic effects are increasing too, in particular CO2 emissions, which result in global warming and climate changes. CO2 emissions, a by-product of vehicles are much higher in cities due to traffic density. According to European standards, Celje is not a large city however its traffic poses a great problem that the city authorities will soon be confronted with. This paper focuses on the city centre of Celje, where traffic flow was measured and CO2 emissions calculated. Using alternative solutions the aim was to present impacts on the environment in the municipality of Celje in an event of changed traffic regimes. In order to reach the guidelines of sustainable transport development in the municipality of Celje, in the future, different measures for reducing negative external effects of city transport will have to be put into force, for only this way the quality of city life can be improved and compatibility of environmental, economic and social objectives provided. В последние несколько лет объем перевозок увеличивается. Следствие этого является возрастание негативных внешних эффектов обусловленных трафиком, и в частности, выбросы CO2, которые приводят к глобальному потеплению и изменению климата. Выбросы CO2, как побочный продукт использования транспортных средств гораздо выше в городах вследствие интенсивности движения. В соответствии с европейскими стандартами, Целье не является большим городом, однако его транспорт создает большую проблему, с чем городские власти в скором времени будут сталкиваться. Данная статья посвящена городскому центру Целье, где транспортные потоки были измерены и рассчитаны выбросы CO2. Целью работы было использование альтернативных решений с тем, чтобы представить воздействие на окружающую среду в городе Целье в случае изменения режимов движения. С тем чтобы обеспечить устойчивое развитие транспорта в городе Целье в будущем, различные меры по снижению негативных внешних эффектов городского транспорта должны быть введены в действие, ибо только таким образом качество городской жизни может быть улучшено и обеспечена совместимость экологических, экономических и социальных целей.

Document type: Article

Pipeline Transport and Blending Energy Requirements for F-T Jet Fuel

Scipedia content — Mon, 25 Jan 2021 19:11:01 +0100

Monte Carlo simulacijski pristop pri določanju lokacij optimalnih avtobusnih postaj v občini Laško

Scipedia content — Mon, 25 Jan 2021 18:41:57 +0100

The paper addresses the problem of optimal bus stop allocation. The aim is to achieve reduction of costs on account of appropriate re-design of the process of obligatory transportation of children from their homes to the corresponding schools in the Laško municipality. The proposed algorithm relies on optimization based on the Monte Carlo simulation procedure. The number of calculated bus stops is required to be minimal possible, which can still assure maximal service area within the prescribed radius, while keeping the minimal walking distances pupils have to go across from their homes to the nearest bus stop and vice versa. The main issues of the proposed algorithm are emphasised and the working mechanism is explained. The presentation of calculated results is given and comparison with some other existing algorithms is provided. The positions of the calculated bus stops are going to be used for the purpose of physical bus stops implementation in order to decrease the current transportation costs. V prispevku je predstavljen problem določanja lokacij optimalnih avtobusnih postaj za potrebe zmanjševanja stroškov, nastalih zaradi prevoza otrok v občini Laško. Te je potrebno na osnovi zakonskih predpisov vsak dan razvoziti na pripadajoče šole ter jim zagotoviti vrnitev domov. Algoritem temelji na optimizaciji s pomočjo Monte Carlo simulacijske metode, pri čemer se izračunajo lokacije optimalnih avtobusnih postaj. Algoritem je sposoben izračunati najmanjše možno število avtobusnih postaj, ki pa bodo vseeno zagotavljale največje možno pokritje učencev v okviru predpisanega največjega radija pešačenja. Pri tem bo učencem potrebno prehoditi kar najkrajšo možno pot od doma do najbližje postaje in obratno. V prispevku so opisane glavne značilnosti delovanja mehanizma predlaganega algoritma. Prav tako je podan tudi prikaz vseh pomembnih izračunanih rezultatov in primerjava z nekaterimi drugimi obstoječimi algoritmi. Pozicije izračunanih avtobusnih postaj se bodo uporabile pri njihovi kasnejši fizični implementaciji z namenom kar največjega možnega zmanjšanja transportnih stroškov.

Recovery Act: 'Carbonsheds' as a Framework for Optimizing United States Carbon Capture and Storage (CCS) Pipeline Transport on a Regional to National Scale

Scipedia content — Mon, 25 Jan 2021 18:33:24 +0100

Carbonsheds are regions in which the estimated cost of transporting CO{sub 2} from any (plant) location in the region to the storage site it encompasses is cheaper than piping the CO{sub 2} to a storage site outside the region. We use carbonsheds to analyze the cost of transport and storage of CO{sub 2} in deploying CCS on land and offshore of the continental U.S. We find that onshore the average cost of transport and storage within carbonsheds is roughly $10/t when sources cooperate to reduce transport costs, with the costs increasing as storage options are depleted over time. Offshore transport and storage costs by comparison are found to be roughly twice as expensive but t may still be attractive because of easier access to property rights for sub-seafloor storage as well as a simpler regulatory system, and possibly lower MMV requirements, at least in the deep-ocean where pressures and temperatures would keep the CO{sub 2} negatively buoyant. Agent-based modeling of CCS deployment within carbonsheds under various policy scenarios suggests that the most cost-effective strategy at this point in time is to focus detailed geology characterization of storage potential on only the largest onshore reservoirs where the potential for mitigating emissions is greatest and the cost of storage appears that it will be among the cheapest.

Reduction of the roundabout capacity due to a strong stream of pedestrians and/or cyclists

Scipedia content — Mon, 25 Jan 2021 18:15:30 +0100

Single-lane roundabouts may face the problems of getting crowded and empty in their circulatory roadway due to a strong stream of pedestrians and/or cyclists. Vehicles at the roundabout entries or exits have to provide the right of way over pedestrians and/or cyclists. Therefore, it comes to disturbances and traffic jams. If there are jams at the entry carriageway, vehicles are unable to get into roundabouts. If there are jams at the exit carriageway, vehicles are not able to leave the roundabout. When the length of vehicle platoon at the exits so long that it reaches the preceding entry, the roundabouts suffer from getting fully overcrowded. The paper presents the methodology of calculating the reduction of the roundabout capacity due to the pedestrian or cyclist stream. The method of calculating the reduction of the roundabout capacity with the disturbed streams may be used for roundabouts in urban environments, where the strength of the cyclist or pedestrian streams is not negligible. V krožnih križiščih z enim voznim pasom v krožnem toku lahko, zaradi močnega toka pešcev in/ali kolesarjev, nastopajo problemi polnjenja in praznjenja krožnega križišča. Vozila na vhodih/izhodih v krožno križišče morajo pešcem/kolesarjem odstopiti prednost. Vsled tega prihaja do oviranosti tokov in zastojev. V primeru, da do zastojev prihaja na vhodu, vozila ne morejo uvažati v krožno križišče. V primeru, da do zastojev prihaja na izhodu, vozila ne morejo zapuščati krožnega križišča. V primeru, ko je dolžina vozil v koloni tako dolga, da doseže predhodni vhod, prihaja do problemov s polnjenjem krožnega križišča. V prispevku je prikazana metodologija izračuna zmanjšanja kapacitete krožnega križišča zaradi tokov kolesarjev in pešcev. Metodologija izračuna zmanjšanja kapacitete krožnega križišča s pomočjo oviranih tokov je uporabna pri krožnih križiščih v urbanih sredinah, kjer so jakosti prometnih tokov kolesarjev in pešcev nezanemarljive.

Sustainable Transportation Program 2011 Annual Report

Scipedia content — Mon, 25 Jan 2021 18:05:57 +0100

Highlights of selected research and development efforts at Oak Ridge National Laboratory funded by the Vehicle Technologies Program, Biomass Program, and Hydrogen and Fuel Cells Program of the Department of Energy, Office of Energy Efficiency and Renewable Energy; and the Department of Transportation.

Petroleum, Pipeline, Transport

Scipedia content — Mon, 25 Jan 2021 17:37:47 +0100

Outsourcing of Logistics Activities in Manufacturing Industry

Scipedia content — Mon, 25 Jan 2021 17:32:14 +0100

The external supply of logistics services is part of a trend toward outsourcing non-core logistics activities. The scope of third-party logistics may range from a relatively limited combination of activities (e.g. transportation and warehousing) to a comprehensive set of logistics services. The authors first discuss the characteristics of business logistics in manufactoring industry, to be taken into account in logistics outsourcing. They particularly point out the motivations for logistics outsourcing, the possibilities of outsourcing, as well as supplier selection. Finally they analyze the outsourcing in the reverse logistics. Vanjska opskrba (outsourcing) logističkih usluga predstavlja dio opće sklonosti tvrtki da prenesu pojedine aktivnosti na za to specijalizirane tvrtke, koje mogu te aktivnosti izvesti na visokoj razini. Ovo područje naziva se trećim dijelom logistike, a kreće se od relativno ograničene kombinacije aktivnosti (primjerice transporta i skladištenja), pa sve do sustavnog pristupa brojnim logističkim i inim aktivnostima. Autori u ovoj raspravi najprije posvećuju pozornost značajkama poslovne logistike u industrijskim proizvodnim tvrtkama, koje zavrjeđuju da budu uzete u razmatranje glede vanjske opskrbe logističkim uslugama (outsourcing). Posebice se prikazuju mogućnosti i motivi za odabir vanjskih opskrbljivača logističkim uslugama, kao i način selekcioniranja ponuđača. Na kraju se analiziraju osobitosti outsourcinga povratne logistike.

Kazakhstan : Taking Advantage of Trade and Openness for Development

Scipedia content — Mon, 25 Jan 2021 17:31:06 +0100

This report is structured as follows. Chapter one analyzes the performance of Kazakhstan s trade. Chapter two presents an overview of recent developments in Kazakhstan regional and international trade integration. Chapter three examines in detail key issues related to market access, focusing on non-tariff measures and trade facilitation and logistics. Chapter four examines the services sector and offers a roadmap for actions to enhance its competitiveness. Chapter five addresses building institutional capacity for the trade and competitiveness agenda. The report s recommendations are summarized in the following table. In order of the four main messages of the report, they cover balancing regional and international integration efforts, measures to improve access to inputs and export markets by reducing non-tariff barriers and through trade facilitation measures, raising the quality and efficiency of the services sector, and strengthening institutional capacity to implement an effective trade policy and competitiveness agenda.

NIST Workshop on Materials Test Procedures for Hydrogen Pipelines

Scipedia content — Mon, 25 Jan 2021 17:28:42 +0100

Nov pristop k določevanju dolžine preglednosti pasivno zaščitenih nivojskih železniških prehodov

Scipedia content — Mon, 25 Jan 2021 17:26:13 +0100

The paper is based on the question whether the existing (legislation determined) method for determining the visibility length on passive protected level railroad crossings insures the relevant level of traffic safety. It has been recognised that using of such method does not provide stopping of road driver vehicles in front of railroad crossing in all conditions. Based on such conclusion a new approach to determining visibility length on passive protected level railroad crossing is proposed. The new approach is based on the assumption that it is necessary, primarily on level railroad crossings with local roads to recognize the worst possible and expected road and weather conditions. The testing of the proposed method in the real environment has shown that at lower speeds of road vehicles there is almost no difference, and that important benefits are recognised for the speeds of 30 and 50km/h where longer stopping distances of road vehicles have been detected (road vehicle can stop safely in front of a rail crossing) with almost the same visibility lengths. The use of the proposed method could have important impact on the increase of traffic safety on passive protected level railroad crossings. Pričujoči prispevek temelji na vprašanju, če obstoječa zakonsko določena metoda za določevanje dolžine preglednosti na pasivno zaščitenih železniških prehodih zagotavlja ustrezni nivo prometne varnosti. Ugotovljeno je, da uporaba obstoječe metode ne omogoča vozniku motornega vozila zaustavitve vozila v vseh pogojih. Na osnovi takšne ugotovitve je predlagan nov pristop k določevanju dolžine preglednosti na pasivno zaščitenih nivojskih železniških prehodih. Nov pristop temelji na predpostavki, da je nujno, predvsem na nivojskih železniških prehodih lokalnih cest, upoštevati najslabše možne in pričakovane cestne in vremenske pogoje. Preizkus predlagane metode v realnem prometnem okolju je pokazal, da pri nižjih hitrosti cestnih vozil skoraj ni razlike, pomembnejše prednosti se pokažejo pri hitrostih 30 in 50 km/h, kjer so ugotovljene večje dolžine zaustavljanja cestnega vozila (cestno vozila se lahko varno zaustavi pred nivojskim železniškim prehodom) pri skoraj enakih dolžinah preglednega polja. Uporaba predlagane metode lahko pomembno prispeva k povečanju prometne varnosti na nivojskih železniških prehodih zaščitenimi samo z Andrejevim križem.

Botswana Development Policy Review : An Agenda for Competitiveness and Diversification

Scipedia content — Mon, 25 Jan 2021 17:26:04 +0100

Botswana has been one of the most successful countries in the developing world over the last 40 years by many measures. Incomes have grown at a sustained pace, poverty has fallen, and the citizenry has become more educated. To be sure, poverty and income inequalities remain a problem, but rising standards of living have meant a better life for this generation of Batswana than any before it. The question facing the country leadership is whether this commendable performance can be sustained into the next generation. There are clouds on the horizon that cannot be ignored. Diamond earnings, the life blood of decades of prosperity, have flattened out. In per capita terms they are falling. Moreover, because revenues from diamonds going to the public sector have been falling for more than a decade, a growth model predicated upon an ever expanding state presence is not viable. Diamond earnings accruing to the state for subsequent redistribution have peaked. Employment and wages in the public sector have reached their natural limits as a share of Gross Domestic Product (GDP); recycling revenues from mining into the private sector, either directly or through the financial sector, has been inefficient with low social returns; and redistributive mechanisms to support social safety nets are also likely be approaching their limits. The country confronts the challenge of looking for new sources of growth outside of government.

Radar-cross-section reduction of wind turbines. part 1.

Scipedia content — Mon, 25 Jan 2021 17:14:58 +0100

In recent years, increasing deployment of large wind-turbine farms has become an issue of growing concern for the radar community. The large radar cross section (RCS) presented by wind turbines interferes with radar operation, and the Doppler shift caused by blade rotation causes problems identifying and tracking moving targets. Each new wind-turbine farm installation must be carefully evaluated for potential disruption of radar operation for air defense, air traffic control, weather sensing, and other applications. Several approaches currently exist to minimize conflict between wind-turbine farms and radar installations, including procedural adjustments, radar upgrades, and proper choice of low-impact wind-farm sites, but each has problems with limited effectiveness or prohibitive cost. An alternative approach, heretofore not technically feasible, is to reduce the RCS of wind turbines to the extent that they can be installed near existing radar installations. This report summarizes efforts to reduce wind-turbine RCS, with a particular emphasis on the blades. The report begins with a survey of the wind-turbine RCS-reduction literature to establish a baseline for comparison. The following topics are then addressed: electromagnetic model development and validation, novel material development, integration into wind-turbine fabrication processes, integrated-absorber design, and wind-turbine RCS modeling. Related topics of interest, including alternative mitigation techniques (procedural, at-the-radar, etc.), an introduction to RCS and electromagnetic scattering, and RCS-reduction modeling techniques, can be found in a previous report.

Management of traffic congestion in urban areas

Scipedia content — Mon, 25 Jan 2021 17:14:31 +0100

The use of road vehicles is increasing, the benefits they afford have been progressively diminished by external costs. Whereas traffic increases as we approach the centre, the road and open space decreases. The greater specialisation allows the city growth in size and in traffic attraction. In this way urban growth feeds itself. Inter-urban transport facilities also become more extensive. Growth in size of the city generates greater amounts of traffic and can eventually give rise to agglomeration diseconomies. Higher transport costs, offices and shops, attracted by the accessibility of central locations, gradually replace residential uses, people being forced to seek housing in the suburbs. As the urban area expands and offices in the city centre are built denser and higher, traffic congestion increases. This may result in the fall in central land values, since accessibility diminishes with the saturation of transport network. Increased pollution takes various forms as noise, smoke and overcrowded housing in the centre, urban decay in the transitional zone as commercial development is anticipated. Uporaba cestnih vozil narašča, korist, ki so jih vozila prinesla pa se pospešeno zmanjšuje zaradi eksternih stroškov, povzročenih s stroški. Kjer promet narašča, predvsem v mestnih središčih, se zmanjšuje prostor na cestah in na javnih površinah. Večja specializacija mestnih središč omogoča njihova rase po obsegu in prometni privlačnosti. Na ta način hrani urbana rast sama sebe. Notranje urbana transportne naprave postajajo man) uporabne. Rast mesta po velikosti generira obseg in število vozil, s tem prometne zgostitve, kar vodi k ekonomskim težavam.. Visoki transportni stroški, obseg poslovnih prostorov in trgovin, ki se veča s privlačnostjo zaradi dostopnosti centralnih območij, postopoma zamenjujejo stanovanjsko gradnjo v središčih mest, in ljudje so prisiljeni iskati bivališča v primestnih predelih. Zaradi tega se mestna središča še bolj gosto in visoko pozidujejo, narašča pa prometna zgostitev. Vse to prispeva postopoma k manjši vrednosti stavbnih zemljišč v središčnih območjih, saj je dostopnost središč vse manjša zaradi vse večje obremenitve prometnic. Veča se onesnaževanje vseh vrst hrupa, emisij vseh vrst, veča se prenaseljenost središč, s tem je urbani razkroj območij poslovnih dejavnosti zagotovljen.

Real capacity of ropeway transportation subsystem

Scipedia content — Mon, 25 Jan 2021 17:12:44 +0100

The ropeway transportation system plays a major role in mountain resorts. In order to provide a sustainable development of the entire mountain resort system, the real capacity of the ropeway transportation system was set. The real capacity of the ropeway transportation system is one of the indicators of the development harmonisation level of single system elements. The research into this field was carried out at the Road Traffic Centre of the Faculty of Civil Engineering, University of Maribor. The paper deals with the basic points of the topic and the methods used. The know-how transfer of experiences into the Slovenian environment is presented together with the obtained results. V sistemu gorskih športno turističnih centrov ima izjemno pomembno vlogo žičniški prometni podsistem. Zanj je značilna izjemna prepletenost medsebojnih vplivov posameznih elementov sistema. S ciljem zagotavljanja trajnostno usklajenega razvoja celotnega sistema gorsko turističnih centrov je bila v okviru raziskav s tega področja v Centru za ceste in cestni promet na Oddelku za promet, Fakultete za gradbeništvo Univerze v Mariboru določena realna kapaciteta žičniškega prometnega sistema. Izkazalo se je, da je izjemno uporabna kot pokazatelj stopnje usklajenosti razvoja posameznih elementov obravnavanega sistema. V članku so prikazana temeljna izhodišča, metoda in rezultati raziskovanja tega področja ter rezultati prenosa novih znanj v slovensko okolje.

Russian Economic Report, No. 28, Autumn 2012 : Reinvigorating the Economy

Scipedia content — Mon, 25 Jan 2021 17:10:45 +0100

Early in the year, as the global economy was slowing and the euro area entered a recession, Russia's economy held steady. But now, as 2012 is entering its final quarter, growth is slowing. Just at a time when Russia's output levels have exceeded the pre-crisis peak, the economy is settling onto a lower trajectory, even though oil prices have stayed high. But let us start with the strong points. The economy had a good first half of the year. While growth was stalling in Europe and slowing in other emerging economies, it remained steady in Russia. Key economic indicators were near or at record levels: the current account surplus stayed high and the Central Bank of Russia added to its reserves, helping to bolster market confidence. Capital outflows, long regarded as one of the soft spots of Russia's economy, declined in the second and third quarters of 2012 from the peaks in the previous two quarters. Whereas many countries in Europe are struggling with large public debt and high fiscal deficits, Russia's federal government public debt is close to single digit and the fiscal balance is in surplus. Inflation and unemployment rates declined to their lowest level in two decades. As people's purchasing power improved and more people had jobs, fewer people were in poverty than at any time since the beginning of the economic transition. A challenging external environment and worsening sentiments among businesses and consumers translate into weak growth prospects. Excluding the crisis years of 1998 and 2009, growth in 2012 is set to decline to its lowest rate in a decade and a half. And 2013 is unlikely to look much better. The weak outlook means that strong, three-pronged policy action is essential to reinvigorate the economy. First, economic policies have to ensure stability. The recent tightening in monetary policy was an important step in this direction. Second, Russia has to build buffers against the external volatility. This means replenishing the reserve fund, moving towards inflation targeting and strengthening banking supervision. Finally, the government has to lift the growth potential of the economy. This means raising productivity and competitiveness, diversifying the economy, and improving transport connectivity, as discussed in the last section of this report, in line with its longer-term economic policy goals. Making headway on this agenda will enable Russia to lift growth above 4 percent and more.

Green Corridor East Africa. Horticultural supply chain Kenya – Europe

Scipedia content — Mon, 25 Jan 2021 17:07:51 +0100

The goal of this project is to gain insight into the current / existing horticultural supply chain (= flower) from Kenya to the Netherlands (Schiphol) and / or Germany (Frankfurt) with inland transport services to the country of destination (= Poland / Warsaw) with a focus on CO2-emission. And also showing the consequences and give recommendations, focussing on CO2-emission, related to possible changes.

Greenhouse Gas Emissions and Price Elasticities of Transport Fuel Demand in Belgium

Scipedia content — Mon, 25 Jan 2021 16:49:13 +0100

Since 1990, Belgium has managed to bring down greenhouse gas emissions in most domains of economic activity. Road transport, as in many other countries, is a notable exception to this pattern: emissions have steadily increased, driven by an ever higher consumption of petrol and diesel. Even though the current overall performance will probably be sufficient to reach the reduction objectives of the Kyoto protocol, transport emissions thus need to be targeted in the future. One possible measure aimed at reducing them, an increase in fuel taxes, is examined in detail in this paper. The success of such a policy depends on the price elasticity of fuel demand, and therefore, the latter is estimated for Belgium and other European countries. The elasticities obtained are relatively small: in Belgium, for instance, a 10% increase in prices would cause consumption to fall by around 1.8% in the short-run and 2.3% in the medium run. Tax increases alone will thus certainly be insufficient for cutting emissions at this time horizon. Nevertheless, as a supporting measure in a more general reduction strategy, they could still yield substantial advantages. This Working Paper relates to the 2011 OECD Economic Review of Belgium (www.oecd.org/eco/surveys/Belgium). Emissions de gaz a effet de serre et elasticites-prix de la demande de carburants en Belgique Depuis 1990, la Belgique a reussi a reduire ses emissions de gaz a effet de serre (GES) dans la plupart des domaines d'activite economique. Comme dans de nombreux autres pays, le transport routier constitue a cet egard une exception notable : ses emissions ont regulierement augmente, sous l'effet d'une consommation toujours croissante d'essence et de gazole. Meme si les performances globales actuelles seront sans doute suffisantes pour atteindre les objectifs de reduction des emissions de GES du Protocole de Kyoto, un objectif doit donc etre defini pour les futures emissions des transports. Une des mesures envisageables pour les faire diminuer, une hausse des taxes sur les carburants, est examinee de maniere approfondie dans ce document. La reussite d'une telle mesure depend de l'elasticite-prix de la demande de carburants, ce qui nous amene a estimer celle-ci pour la Belgique et d'autres pays europeens. Les elasticites obtenues sont relativement modestes : en Belgique, par exemple, une hausse des prix de 10 % entrainerait un recul de la consommation de l'ordre de 1.8 % a court terme, et de 2.3 % a moyen terme. De simples augmentations des taxes seront donc certainement insuffisantes pour reduire les emissions a cet horizon. Neanmoins, en tant que mesures d'accompagnement s'inscrivant dans le cadre d'une strategie plus generale de reduction des emissions de GES, elles pourraient avoir des retombees positives substantielles. Ce Document de travail se rapporte a l’Etude economique de l’OCDE de la Belgique 2011 (www.oecd.org/eco/etudes/Belgique).

Solid Oxide Fuel Cell Systems PVL Line

Scipedia content — Mon, 25 Jan 2021 16:43:46 +0100

In July 2010, Stark State College (SSC), received Grant DE-EE0003229 from the U.S. Department of Energy (DOE), Golden Field Office, for the development of the electrical and control systems, and mechanical commissioning of a unique 20kW scale high-pressure, high temperature, natural gas fueled Stack Block Test System (SBTS). SSC worked closely with subcontractor, Rolls-Royce Fuel Cell Systems (US) Inc. (RRFCS) over a 13 month period to successfully complete the project activities. This system will be utilized by RRFCS for pre-commercial technology development and training of SSC student interns. In the longer term, when RRFCS is producing commercial products, SSC will utilize the equipment for workforce training. In addition to DOE Hydrogen, Fuel Cells, and Infrastructure Technologies program funding, RRFCS internal funds, funds from the state of Ohio, and funding from the DOE Solid State Energy Conversion Alliance (SECA) program have been utilized to design, develop and commission this equipment. Construction of the SBTS (mechanical components) was performed under a Grant from the State of Ohio through Ohio's Third Frontier program (Grant TECH 08-053). This Ohio program supported development of a system that uses natural gas as a fuel. Funding was provided under the Department of Energy (DOE) Solid-state Energy Conversion more » Alliance (SECA) program for modifications required to test on coal synthesis gas. The subject DOE program provided funding for the electrical build, control system development and mechanical commissioning. Performance testing, which includes electrical commissioning, was subsequently performed under the DOE SECA program. Rolls-Royce Fuel Cell Systems is developing a megawatt-scale solid oxide fuel cell (SOFC) stationary power generation system. This system, based on RRFCS proprietary technology, is fueled with natural gas, and operates at elevated pressure. A critical success factor for development of the full scale system is the capability to test fuel cell components at a scale and under conditions that can be accurately extrapolated to full system performance. This requires specially designed equipment that replicates the pressure (up to 6.5 bara), temperature (about 910 C), anode and cathode gas compositions, flows and power generation density of the full scale design. The SBTS fuel cell anode gas is produced through the reaction of pipeline natural gas with a mixture of steam, CO2, and O2 in a catalytic partial oxidation (CPOX) reactor. Production of the fuel cell anode gas in this manner provides the capability to test a fuel cell with varying anode gas compositions ranging from traditional reformed natural gas to a coal-syngas surrogate fuel. Stark State College and RRFCS have a history of collaboration. This is based upon SSCAs commitment to provide students with skills for advanced energy industries, and RRFCS need for a workforce that is skilled in high temperature fuel cell development and testing. A key to this approach is the access of students to unique SOFC test and evaluation equipment. This equipment is designed and developed by RRFCS, with the participation of SSC interns. In the near-term, the equipment will be used by RRFCS for technology development. When this stage is completed, and RRFCS has moved to commercial products, SSC will utilize this equipment for workforce training. The RRFCS fuel cell design is based upon a unique ceramic substrate architecture in which a porous, flat substrate (tube) provides the support structure for a network of solid oxide fuel cells that are electrically connected in series. These tubes are grouped into a {approx}350-tube repeat configuration, called a stack/block. Stack/block testing, performed at system conditions, provides data that can be confidently scaled to full scale performance. This is the basis for the specially designed and developed test equipment that is required for advancing and accelerating the RRFCS SOFC power system development program. All contract DE-EE0003229 objectives were achieved and deliverables completed during the period from March 1, 2010 through March 31, 2011. As a result of program completion, the Stack Block Test System was ready to support installation and electrical operation of a RRFCS solid oxide fuel cell (SOFC) stack block in the second quarter of 2011. « le

Cameroon Economic Update, July 2012 : Stepping Out into the World

Scipedia content — Mon, 25 Jan 2021 16:41:26 +0100

With this Cameroon economic update, the World Bank is pursuing a program of short, crisp and frequent country economic reports. These economic updates provide an analysis of the trends and constraints in Cameroon's economic development. Each issue, produced bi-annually, provides an update of recent economic developments, as well as a special focus on a topical issue. The economic updates aim to share knowledge and stimulate debate among those interested in improving the economic management of Cameroon and unleashing its enormous potential. This fourth issue of the Cameroon economic update is entitled 'stepping out into the world a special focus on trade facilitation'. It reviews the challenges and opportunities related to trade facilitation in Cameroon. The coverage is not meant to be exhaustive, but puts an emphasis on particular areas that would require the country's sustained attention: a transformative trade facilitation agenda around which all stakeholders could be mobilized.

Agribusiness Indicators : Tanzania

Scipedia content — Mon, 25 Jan 2021 16:33:48 +0100

griculture in Tanzania accounts for 28 percent of the country's Gross Domestic Product (GDP) and employs 80 percent of its labor force. The sector is also an important source of export revenues. The data and findings presented in this report provide a summary of the performance of the agriculture sector in Tanzania using a set of indicators covering six areas. These are: 1) access to and availability of certified seed; 2) availability of and access to fertilizer; 3) access to farm machinery, particularly tractor hire services for land preparation; 4) access to agricultural and agro-enterprise finance; 5) the cost and efficiency of transporting agricultural commodities; and 6) measures of policy certainty and uncertainty as perceived by private investors and the effects these have on the enabling environment for producers and agribusinesses. The Agribusiness Indicators (ABI) team conducted interviews with Government agencies, private firms (fertilizer importers, seed companies, tractor importers and distributors, transporters), commercial banks, farmer-based organizations, donors, and Non Governmental Organizations (NGOs). The ABI program is pilot testing an initial set of indicators on the ease (or difficulty) of operating agribusinesses in African countries. The indicators are used to assess whether the countries have an enabling environment that is conducive to agribusiness investment, competitiveness, and ultimately agriculture-led growth.

Uklajevanje razvoja žičniške in turistične infrastrukture gorskih športno turističnih centrov

Scipedia content — Mon, 25 Jan 2021 15:05:48 +0100

Operation efficiency of mountain resort systems depends largely on harmonious operation of the most important and therefore most influential elements of ropeway transportation and tourist subsystems. Within the framework of a tourist subsystem, the extent and quality of tourist offer for long-staying guests plays an essential role. Harmonised development of the above-mentioned elements ensures major utilisation and better economic management of the entire system so that it may offer quality services. First of all, the system enables permanent and environmentally friendly development of the systems that are as a rule in an absolutely sensitive alpine region. The article deals with some results of in-depth research on the ropeway transportation system and the results of know-how transfer into the actual environment of the Slovenian mountain resorts. UÄinkovitost delovanja sistema gorskih Å¡portno turistiÄnih centrov je v najveÄji meri odvisna od usklajenosti delovanja najpomembnejÅ¡ih ter s tem najvplivnejÅ¡ih elementov - Å¾iÄniÅ¡kega prometnega ter turistiÄnega podsistema. V okviru turistiÄnega podsistema ima najpomembnejÅ¡o vlogo obseg in kvaliteta stacionarne turistiÄne ponudbe. Usklajen razvoj omenjenih elementov zagotavlja veÄjo izkoriÅ¡Äenost ter kvaliteto storitev sistema, predvsem pa zagotavlja trajnosten in z zahtevami okolja usklajen razvoj sistemov, ki se praviloma nahajajo v okoljsko izjemno obÄutljivem alpskem podroÄju. V Älanku so predstavljeni nekateri rezultati poglobljenih raziskav iz omenjenega podroÄja ter rezultati prenosa teh znanj v realno okolje slovenskih gorskih Å¡portno turistiÄnih centrov.

Assessing the Impact of Prices Fluctuation on Demand Distortion Within a Multi-echelon Supply Chain

Scipedia content — Mon, 25 Jan 2021 14:57:51 +0100

Price fluctuation is a practice commonly used by companies to stimulate demand and a main cause of the Bullwhip effect. Assuming a staggered step demand pattern that responds elastically to retailerâs price fluctuation, and by using a supply chain management dynamic model, we will analyse the impact of these fluctuations on the variability of the orders placed along a traditional multilevel supply chain. Subsequently, the results obtained will serve to propose a forecasting model enabling to calculate the potential variability of orders placed by each echelon on the basis of the price pattern used. Finally, under the hypothesis of an environment of collaboration between the different members of the chain, we propose a predictive model that makes it possible to quantify the distortion of the orders generated by each level. En este artÃculo se analiza la influencia de la fluctuacion de los precios en la variabilidad de las Ã³rdenes generadas a lo largo de una cadena de suministro tradicional multinivel. Para ello, se utiliza un modelo dinÃ¡mico de gestiÃ³n de ca- dena de suministro en el que se introduce un patrÃ³n de de- manda tipo escalÃ³n, que responde elÃ¡sticamente a la fluc- tuaciÃ³n de los precios ofrecidos por el minorista al cliente final. Posteriormente, utilizando los resultados obtenidos, se propone un modelo de previsiÃ³n para calcular esa posible variaciÃ³n de las Ã³rdenes generadas en cada nivel, a partir del patrÃ³n de precios utilizado.

Tajikistan Economic Report, 2012 : Sustaining Post-Crisis Recovery, Investment and Growth

Scipedia content — Mon, 25 Jan 2021 14:51:47 +0100

Tajikistan is one of the world's most remittance-dependent economies, receiving net remittance inflows equivalent to approximately 40 percent of Gross Domestic Product (GDP). Falling remittance inflows was one of the main transmission channels through which the 2008-09 global economic crisis adversely impacted the economy. Conversely, the pickup in growth since 2009 can also be traced to the rebound in remittance inflows (primarily from Russia, where more than 90 percent of Tajik migrants work), which reached 42 percent of GDP in 2010 and an estimated 40 percent of GDP in 2011. As the World Bank's 2011 country economic memorandum has argued, future growth in Tajikistan will depend crucially on increasing efficiency and raising private investment rates. Remittances are likely to grow more slowly than the earlier trend over the last 5-6 years, but could nonetheless be a major contributor to future growth if more go into private investment than in the past.

Novi tip krožnega križišča: krožno križišče s ”pritisnjenimi” pasovi za desne zavijalce – ”flower roundabout”

Scipedia content — Mon, 25 Jan 2021 14:44:17 +0100

Recently, many of the foreign traffic-safety analyses point out the low level of traffic safety in multi-lane roundabouts. This problem is resolved in several ways in different countries however, the solution, whereby the number of conflict points is diminished (e.g. turbo roundabout) has proven to be the most successful. However, the turbo roundabout also has its deficiencies: it has conflict crossing points and larger reconstruction of the existing two-lane roundabout is needed when the turbo roundabout is to be implemented instead of the existing one. In the paper a new type of roundabout has been introduced the roundabout with âdepressedâ lanes for right turning (âthe flower-roundaboutâ). Financially speaking, the main advantage of the new type of roundabout is that it can be implemented within the dimensions of the already existing ânormalâ two-lane roundabout. From the traffic-safety point of view, the main advantage of the new type of roundabout is that it has no crossing conflict points. V zadnjem Äasu mnoge tuje prometno-varnostne analize kaÅ¾ejo na nizko raven prometne varnosti veÄpasovnih kroÅ¾nih kriÅ¾iÅ¡Ä. Ta problem v razliÄnih drÅ¾avah reÅ¡ujejo na razliÄne naÄine, kot najuspeÅ¡nejÅ¡i pa se je pokazal naÄin z zmanjÅ¡evanjem Å¡tevila konfliktnih toÄk (npr. turbo kroÅ¾no kriÅ¾iÅ¡Äe). Vendar ima tudi turbo kroÅ¾no kriÅ¾iÅ¡Äe svoje pomankljivosti: ima konfliktne toÄke kriÅ¾anja ter v primeru, da Å¾elimo izvesti turbo kroÅ¾no kriÅ¾iÅ¡Äe namesto obstojeÄega dvopasovnega kriÅ¾iÅ¡Äa, je potrebna veÄja rekonstrukcija kriÅ¾iÅ¡Äa. V prispevku je predstavljen novi tip kroÅ¾nega kriÅ¾iÅ¡Äa - kroÅ¾no kriÅ¾iÅ¡Äe s "pritisnjenimi" pasovi za desno zavijanje. Glavna prednost takÅ¡nega tipa kroÅ¾nega kriÅ¾iÅ¡Äa je, da ga je moÅ¾no izvesti znotraj meja obstojeÄega dvopasovnega kroÅ¾iÅ¡Äa. S staliÅ¡Äa prometne varnosti ta tip kroÅ¾nega kriÅ¾iÅ¡Äa nima konfliktnih toÄk kriÅ¾anja.

Natural Gas Hydrates

Scipedia content — Mon, 25 Jan 2021 12:43:23 +0100

Sir Humphry Davy witnessed the first chlorine hydrate crystallizing in 1811. Couple of century later his discovery, natural gas hydrates has begun to play an important role in energy business. From being a mere chemical curiosity, they have proven to be a nuisance for the natural gas industry. The problem of hydrate induced blockage in âwet gasâ flow systems has been widely reported and became a major flow assurance issue in the energy sector[1]. The importance of pipeline blockage increased in the 70âs when plugging of even the largest diameter pipelines from offshore, arctic fields or the wells from high-pressure underground storage facilities were reported. Studies over the past two decades showed that large gas hydrate plugs form most often after shut-in pipelines or wells begin to flow[2]. When a pipeline is shut-in, the fluid separates into the gas water and hydrocarbons as the temperature decreases[3].

Optical Burst-Switched Networks Exploiting Traffic Engineering in the Wavelength Domain

Scipedia content — Mon, 25 Jan 2021 12:43:04 +0100

In order to simplify the design and operation of telecommunications networks, it is common to describe them in a layered structure constituted by a service network layer on top of a transport network layer. The service network layer provides services to its users, whereas the transport network layer comprises the infrastructure required to support the service networks. Hence, transport networks should be designed to be as independent as possible from the services supported, while providing functions such as transmission, multiplexing, routing, capacity provisioning, protection, and management. Typically, a transport network includes multiple network domains, such as access, aggregation, metropolitan and core, ordered by decreasing proximity to the end-users, increasing geographical coverage, and growing level of traffic aggregation.

A CO2 Emission Trading Scheme for German Road Transport

Scipedia content — Mon, 25 Jan 2021 12:41:11 +0100

Deploying Wireless Sensor Devices in Intelligent Transportation System Applications

Scipedia content — Mon, 25 Jan 2021 12:32:36 +0100

As future intelligent infrastructure will bring together and connect individuals, vehicles and infrastructure through wireless communications, it is critical that robust communication technologies are developed. Mobile wireless sensor networks are self-organising mobile networks where nodes exchange data without the need for an underlying infrastructure. In the road transport domain, schemes which are fully infrastructure-less and those which use a combination of fixed (infrastructure) devices and mobile devices fitted to vehicles and other moving objects are of significant interest to the ITS community as they have the potential to deliver a âconnected environmentâ where individuals, vehicles and infrastructure can co-exist and cooperate, thus delivering more knowledge about the transport environment, the state of the network and who indeed is travelling or wishes to travel. This may offer benefits in terms of real-time management, optimisation of transportation systems, intelligent design and the use of such systems for innovative road charging and possibly carbon trading schemes as well as through the CVHS (Cooperative Vehicle and Highway Systems) for safety and control applications. As the wireless sensor networks technology is still relatively new and very little is known about its real application in the transport domain. Our involvement in the transport-related projects provides us with an opportunity to carry out research and development of wireless sensor network applications in transport systems. This chapter outlines our experience in the ASTRA (ASTRA, 2005), TRACKSS (TRACKSS, 2007) and EMMA (EMMA, 2007) projects and provides an illustration of the important role that the wireless sensor technology can play in future ITS. This chapter also presents encouraging results obtained from the experiments in investigating the feasibility of utilising wireless sensor networks in vehicle and vehicle to infrastructure communication in real ITS applications.

Active Traffic Management as a Tool for Addressing Traffic Congestion

Scipedia content — Mon, 25 Jan 2021 12:31:49 +0100

Recurrent and non-recurrent congestion in urban areas continues to be a major concern due to its adverse impacts on delays, fuel consumption and pollution, driver frustration, and traffic safety. In the U.S., limited public funding for roadway expansion and improvement projects, coupled with continued growth in travel along congested urban freeway corridors, creates a pressing need for innovative congestion management approaches.

Corrosion Control in Industry

Scipedia content — Mon, 25 Jan 2021 12:30:14 +0100

The economic development of any region, state or country, depends not only on its natural reâ sources and productive activities, but also on the infrastructure that account for the exploitaâ tion, processing and marketing of goods. Irrigation systems, roads, bridges, airports, maritime, land and air transport, school buildings, offices and housing, industrial installations are affectâ ed by corrosion and therefore susceptible to deterioration and degradation processes.

Deconvolution of X-Ray Backscatter Diffraction Data for NDE of Corrosion

Scipedia content — Mon, 25 Jan 2021 12:26:44 +0100

The problem of corrosion of steel surfaces under thermal insulation is one that plagues the petroleum, petrochemical, chemical and pipeline industries [1,2]. Often internal surfaces, as well, are subject to attack by moisture, acids or other corrosive influences. Thermal insulation renders traditional NDE methods mostly ineffective but is essentially transparent to x-rays in the energy ranges commonly used for industrial radiography. Since transmission radiography is severely hampered by the need for access to âboth sidesâ of the object being tested, the use of NDE methods employing Compton backscattered x-rays is strongly suggested [3,4]. Through appropriate collimation of incident and backscattered x- rays, depth as well as transverse information concerning the object under examination can be resolved. Access is required only to one side of the object, making the method potentially useful for examination of large vessels as well as pipelines.

Smart Agri-Food Logistics: Requirements for the Future Internet

Scipedia content — Mon, 25 Jan 2021 12:20:38 +0100

The food and agribusiness is an important sector in European logistics with a share in the EU road transport of about 20 %. One of the main logistic challenges in this sector is to deal with the high dynamics and uncertainty in supply and demand. This paper defines requirements on Future Internet (FI) technologies that have to be met to accomplish the specific challenges of agri-food logistics. It identifies a set of generic technical enablers as input for the realisation of a FI core platform. This technology foundation is to be developed and tested in a Future Internet publicâprivate partnership (FI-PPP) environment of over 150 organisations.

How to Manage Failures in Air Traffic Control Software Systems

Scipedia content — Mon, 25 Jan 2021 12:16:28 +0100

Air Traffic Control (ATC) systems are large and complex systems supervising the aircraft trajectories from departure to destination. Such systems have hard reliability and dependability requirements. Having an effective failure management in such kind of critical systems is a must for safety and security reasons. Two main approaches have been developed in the literature to implement these failure management system

Fluid Stochastic Petri Nets: From Fluid Atoms in ILP Processor Pipelines to Fluid Atoms in P2P Streaming Networks

Scipedia content — Mon, 25 Jan 2021 12:14:06 +0100

Â© 2012 Mitrevski and Kotevski, licensee InTech. This is an open access chapter distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Fluid Stochastic Petri Nets: From Fluid Atoms in ILP Processor Pipelines to Fluid Atoms in P2P Streaming Network

Upstream Multiphase Flow Assurance Monitoring Using Acoustic Emission

Scipedia content — Mon, 25 Jan 2021 12:09:31 +0100

An offshore or subsea production facility consists of several satellite wells. The contents of each well are combined and passed onshore via a common pipeline. Each satellite well produces variable quantities of oil, water and gas during its lifetime. However, if different companies own these wells, their flowrates and compositions in pipelines must be monitored and control before any mixing takes place

Modelling, Simulation Methods for Intelligent Transportation Systems

Scipedia content — Mon, 25 Jan 2021 12:08:16 +0100

Effective transportation systems lead to the efficient movement of goods and people, which significantly contribute to the quality of life in every society. In the heart of every economic and social development, there is always a transportation system. Meanwhile, traffic congestion has been increasing worldwide because of increased motorization, urbanization, population growth, and changes in population density. This threatens the social and economic prosperity of communities all over the world. Congestion reduces utilization of the transportation infrastructure and increases travel time, air pollution, and fuel consumption. Therefore, managing and controlling transportation systems becomes a high priority task for every community, as it constitutes a matter of survival and prosperity for humanity.

Health Impacts of Noise Pollution Around Airports: Economic Valuation and Transferability

Scipedia content — Mon, 25 Jan 2021 12:04:39 +0100

Air transportation generates numerous economic and social welfare benefits. Airports and their expansions are associated with direct, indirect, induced effects as well as catalytic impacts on regional and national economies (Arndt et al., 2009; Braun et al., 2010). Mobility and accessibility are important factors determining competitiveness of (regional and national) economies in an increasingly globalised world. On the other hand there are numerous environmental and health impacts related to the growing demand for air transport. Since the projected annual growth rates of numbers of passengers are about 5% in the next 20 to 25 years (Mahashabde et al., 2011), the continuing growth of the aviation sector has raised questions of appropriate valuation and treatment of external costs (e.g. human and environmental health). In the context of transport markets, a distinction of externalities into positive (external benefits) and negative (external costs) is appropriate. Large infrastructure projects like airports cause various external effects, associated especially with the provision of transport services and facilities, the need of constructing transport infrastructure as well as related production of vehicles or raw materials (Schipper et al. 2001). Air traffic and associated ground side traffic contribute to local and global noise and air pollution.

Availability of Training in Visual Inspection for the AIR Transport Industry

Scipedia content — Mon, 25 Jan 2021 11:49:30 +0100

Traditionally nondestructive testing (NDT) has focused on the NDT areas of penetrants, magnetic particle, eddy current, ultrasound, radiographic, and other related areas of NDT. These areas are all well developed with much training available and also full levels of inspector certification(1).

Present and Future Role of Battery Electrical Vehicles in Private and Public Urban Transport

Scipedia content — Mon, 25 Jan 2021 11:42:11 +0100

The OECD estimates that more than 70% of the developed world population lives in urban environments2, which explains a larger concentration of vehicles there. In the EU-27, there were about 230 million passenger vehicles in 2007 and the new vehicle sales were nearly 16 million vehicles in that year. Notwithstanding the improvements in regulated air pollutants from road transport, the urban population remains at higher risk levels by directly suffering the impact of conventional vehicles because of their closeness to the pollutant source. On one hand urbanization means that people when travelling in their urban environment will typically travel less than 100 km a day. And on the other, that a large percentage of all transâ port and delivery of goods will take place in urban areas. Acceleration and deceleration freâ quency, traffic jams, thus energy efficiency and pollution per km are worst within urban traffic. Many business cases exist for urban electrified road transport because these offer a lower Total Cost of Ownership (TCO) than conventional means already today. The above

Routing On Demand: Toward the Energy-Aware Traffic Engineering with OSPF

Scipedia content — Mon, 25 Jan 2021 11:37:33 +0100

Energy consumption has already become a major challenge to the current Internet. Most researches aim at lowering energy consumption under certain fixed performance constraints. Since trade-offs exist between network performance and energy saving, Internet Service Providers (ISPs) may desire to achieve different Traffic Engineering (TE) goals corresponding to changeable requirements. The major contributions of this paper are twofold: 1) we present an OSPF-based routing mechanism, Routing On Demand (ROD), that considers both performance and energy saving, and 2) we theoretically prove that a set of link weights always exists for each trade-off variant of the TE objective, under which solutions (i.e., routes) derived from ROD can be converted into shortest paths and realized through OSPF. Extensive evaluation results show that ROD can achieve various trade-offs between energy saving and performance in terms of Maximum Link Utilization, while maintaining better packet delay than that of the energy-agnostic TE. Â© 2012 IFIP International Federation for Information Processing.

Document type: Part of book or chapter of book

Anomalous Models of Defect Interactions in Electromagnetic Testing

Scipedia content — Mon, 25 Jan 2021 11:35:43 +0100

Stress corrosion cracking (SCC) is a major concern in oil and gas transmission lines. Small external, axially aligned cracks are difficult to detect and size using present boreside inspection techniques. Remote field eddy current (RFEC) testing is an inspection technique for tubes currently in use for the inspection from well casings to small diameter heat exchange tubes. An advantage of this technique over conventional eddy current testing is its ability to detect both external and internal defects in ferromagnetic materials with approximately equal sensitivity. Because of RFECâs proven sensitivity to external defects and the fact that eddy currents are induced in the circumferential direction, there is currently great interest in the technique for the inspection of pipelines.

Gas-Coupled, Pulse-Echo Ultrasonic Crack Detection and Thickness Gaging

Scipedia content — Mon, 25 Jan 2021 11:29:55 +0100

Ultrasonic inspection is a standard method to assess the integrity of large-diameter oil pipelines. However, similar methods applied to natural-gas pipelines present a considerably greater challenge; gas is a poor coupling agent for the probing ultrasonic signals between the transducer and the pipe wall. Natural gas exhibits a very low specific acoustic impedance (300 Rayls for methane at atmospheric pressure) compared to oil (1.5 MRayls and higher). Consequently, large ultrasonic-signal transmission losses occur at the transducer/gas and pipe-wall/gas interfaces. To circumvent this obstacle, past exploratory developments included the use of a liquid-filled wheel [1], electromagnetic-acoustic-transducer (EMAT) [2], and liquid-slug technologies [3]. While prototypes of high-speed, in-line inspection systems employing such principles do exist, all exhibit serious operational shortcomings that prevent widespread commercial exploitation.

Petri nets models for analysis and control of public bicycle-sharing systems

Scipedia content — Mon, 25 Jan 2021 11:28:47 +0100

Public Bicycle-Sharing Systems (PBSS), also known as self-service public bicycle systems, are available in numerous big cities in the world (Velib' in Paris, Bicing in Barcelona, Call-aBicycle in Munich, OyBicycle in London, etc.). Since its inception, Bicycle-sharing programs have grown worldwide. There are now programs in Europe, North America, South America, Asia, and Australia. A still growing list of cities which provides such green public transportation mode can be found at the Bicycle-sharing world map (http://Bikesharing.blogspot.com) as shown in Figure 1. As a good complementary to other urban transportation modes, bicycle use entails a number of benefits including environmental, mobility and economic benefits. The public bicycle sharing systems are especially useful for short-distance city transport trips and to face many public transport problems, including growing traffic congestion, pollution, greater car dependency, buses caught in city congestion, and ageing transport infrastructure.

The Slug Flow Problem in Oil Industry and Pi Level Control

Scipedia content — Mon, 25 Jan 2021 11:26:45 +0100

The slug is a multiphase flow pattern that occurs in pipelines which connect the wells in seabed to production platforms in the surface in oil industry. It is characterized by irregular flows and surges from the accumulation of gas and liquid in any cross-section of a pipeline. In this work will be addressed the riser slugging, that combined or initiated by terrain slugging is the most serious case of instability in oil/water-dominated systems [5, 15, 21].

Barcelona electric mobility tour

Scipedia content — Mon, 25 Jan 2021 11:16:57 +0100

Artificial Intelligence Techniques Applied to Electromagnetic Interference Problems Between Power Lines and Metal Pipelines

Scipedia content — Mon, 25 Jan 2021 11:16:00 +0100

European ecological regulations meant to protect nature and wild life along with construction cost reduction policies generated a set of government regulations that limit the access to new transmission and distribution corridors. As a result, gas, water or oil supply pipelines are forced to share the same distribution corridors with Electrical Power Lines (EPL), AC Railway Systems or Telecommunication Lines (figure 1).

Comprehensive Perspectives in Bioremediation of Crude Oil Contaminated Environments

Scipedia content — Mon, 25 Jan 2021 11:09:31 +0100

Diverse components of crude oil and petroleum such as polycyclic aromatic hydrocarbons (PAHs) have been found in waterways as a result of pollution from industrial effluents and petrochemical products (Beckles, et al., 1998). Petroleum hydrocarbon pollution of the environment may arise from oil well drilling production operations, transportation and storage in the upstream industry, and refining, transportation, and marketing in the downstream industry. Petroleum hydrocarbon pollution could also be from anthropogenic sources (Oberdorster and Cheek, 2000). Some non combusted hydrocarbons escape into the environment during the process of gas flaring. Until recently, the bulk of the associated gas produced during drilling in Nigeria, was flared. Sources of petroleum and its products in the environment will also include accidental spills and from ruptured oil pipelines. Today the international oil and gas-pipelines span several million kilometers and this is growing yearly due to inter-regional trade in petroleum products. Just like any other technical appliance, pipelines are subject to ââtear and wearââ, thus can fail with time (Beller, et al., 1996). Spilled petroleum hydrocarbons in the environment are usually drawn into the soil due to gravity until an impervious horizon is met, for example bedrock, watertight clay or an aquifer.

Telematics in the Transport Environment

Scipedia content — Mon, 25 Jan 2021 11:06:24 +0100

Awareness of an efficient and sustainable vessel traffic management is a result of raised traffic congestion as well as of increased waiting times at locks and inland ports. The established vessel traffic management systems will have to be modified by 2025, to challenge the expected increase in the transport demand on navigable European inland waterways. Substantial benefits to traffic flow optimization are anticipated by the dissemination of an accurate information regarding the waterway and the management of the locks in the waterway network. Positive effects resulting from a harmonised implementation of traffic management systems optimize also the use of waterway infrastructure by means of reducing dredging activities and lock utilization. The outcomes of this paper will give a concise assessment of the benefits of an integrated traffic management implementation to private and public stakeholders of inland navigation.

Addressing Uncertainty about Future Airport Activity Levels in Airport Decision Making

Scipedia content — Mon, 25 Jan 2021 11:02:39 +0100

This report provides a guidebook on how to develop air traffic forecasts in the face of a broad range of uncertainties. It is targeted at airport operators, planners, designers, and other stakeholders involved in planning, managing, and financing of airports, and it provides a systems analysis methodology that augments standard master planning and strategic planning approaches. This methodology includes a set of tools for improving the understanding and application of risk and uncertainty in air traffic forecasts as well as for increasing overall effectiveness of airport planning and decision making. In developing the guidebook, the research team studied existing methods used in traditional master planning as well as methods that directly address risk and uncertainty, and based on that fundamental research, they created a straightforward and transparent systems analysis methodology for expanding and improving traditional planning practices, applicable through a wide range of airport sizes. The methods presented were tested through a series of case study applications that also helped to identify additional opportunities for future research and long-term enhancements.

Open Initiatives: Offenheit in der digitalen Welt und Wissenschaft

Scipedia content — Mon, 25 Jan 2021 10:54:16 +0100

Abstract in English language: Initiatives that are calling for transparency, open and easy access to information (of academic, administrative or any other origin) are gaining momentum and are beginning to differentiate more and more. The claims range from Free Access to information to Open Access according to the principles of the Open Source community. Some initiatives focus more on transparency rather than on openness, such as the whistleblower platform Wikileaks, while others (e.g. Open Government and Open Access to Research Data) combine the demands for transparency and openness or focus on the provision of non-proprietary information (like the geodata project OpenStreetMap or Open Metrics concepts in the scientific area). Twelve authors from different Open Data projects and from the context of Open Access to scientific information, Open Science, journalism and law analyze the Open Initiatives and discuss their common limitations as well as radical concepts of Openness such as WikiLeaks and Anonymous. Abstract in German language: Initiativen, die Transparenz, offenen und mÃ¶glichst einfachen Zugang zu Informationen, etwa in Wissenschaft und Verwaltung fordern und herstellen, gewinnen rasant an Bedeutung und beginnen sich immer weiter zu differenzieren. Die Forderungen reichen von freiem (im Sinne von kostenlosem) Zugang zu Informationen bis hin zu offenem Zugang analog den Prinzipien der Open Source Community. Manche Initiativen und PhÃ¤nomene fokussieren stÃ¤rker auf Transparenz als auf Offenheit, wie z.B. die Whistleblower-Plattform Wikileaks, wÃ¤hrend wiederum andere (z.B. Open Government oder Open Access zu Forschungsdaten) die Forderungen nach Transparenz und Offenheit kombinieren oder sich an der Bereitstellung nicht-proprietÃ¤rer Informationen versuchen (wie das Geodaten-Projekt OpenStreetMap oder die Open Metrics Konzepte im Wissenschaftskontext). ZwÃ¶lf Autorinnen und Autoren aus Open Data Projekten und aus den Bereichen Open Access, Open Science, Journalismus und Recht beschreiben und analysieren die besagten und andere Open Initiatives, diskutieren deren Gemeinsamkeiten und Grenzen sowie radikale Offenheitskonzepte wie WikiLeaks und Anonymous.

A Multi-Agent Approach for Designing Next Generation of Air Traffic Systems

Scipedia content — Mon, 25 Jan 2021 10:48:06 +0100

Current implementation of new technologies for Communication, Navigation, Surveillance and Air Traffic Management (CNS/ATM systems) along with computational improvements on airborne and ground systems developed in the last two decades, point out the need for more strategic navigation and air-traffic control procedures based on four-dimensional (position plus time) trajectories. Moreover, the CNS/ATM infrastructure will help to achieve more shared real-time information among aircraft, airlines and air-traffic services providers (i.e. Air Traffic Control âATCproviders, meteorological information providers and air space resources information providers). Then, general requirements for a next-generation of Air Traffic Management (ATM) system is that entities must share real-time information about aircraft state and intentions, air-space state and resources, meteorological conditions and forecast, etc. From this information coordinated and strategic actions should be carried out by them in order to achieve efficient and free of conflict 4D trajectories.

Laser Beam Welding of Austenitic Stainless Steels – Similar Butt and Dissimilar Lap Joints

Scipedia content — Mon, 25 Jan 2021 10:43:58 +0100

Because of its inherent corrosion resistance, austenitic stainless steels, known as 300 series, have become cost-effective, staple materials for long-term applications in many industrial sectors including gas, petroleum, petrochemicals, fertilizers, food processing, and pulp industries as well as power generating plants. They have found also widespread use for manufacturing of chemical installations including stationary pressure tanks and tanks for transport of liquid and compressed gases, pipelines of high diameter in water power plants, for manufacturing of ships for transport of chemicals and installations of drilling rigs, etc. Thick-section stainless steels are widely used in the components and structures for nuclear power plants.

Simulation of Team Cooperation Processes in En-Route Air Traffic Control

Scipedia content — Mon, 25 Jan 2021 10:43:16 +0100

Recent increase in air traffic demands makes the role of Air Traffic Control (ATC), which supports safety and efficiency of aviation, more important than ever. As aviation technologies have progressed, automation and computer supports are being introduced in cockpits, but ATC still heavily relies on human expertise of Air Traffic Control Officers (ATCOs). It is therefore necessary to understand ATC tasks from a viewpoint of ATCOsâ cognitive behaviour in order to assess and improve task schemes and training programs for ATC.

Experience with Restoration of Asia Pacific Network Failures from Taiwan Earthquake

Scipedia content — Mon, 25 Jan 2021 10:37:02 +0100

We explain how network failures were caused by a natural disaster, describe the restoration steps that were taken, and present lessons learned from the recovery. At 21:26 on December 26th (UTC+9), 2006, there was a serious undersea earthquake off the coast of Taiwan, which measured 7.1 on the Richter scale. This earthquake caused significant damage to submarine cable systems. The resulting fiber cable failures shut down communications in several countries in the Asia Pacific networks. In the first post-earthquake recovery step, BGP routers detoured traffic along redundant backup paths, which provided poor quality connection. Subsequently, operators engineered traffic to improve the quality of recovered communication. To avoid filling narrow-bandwidth links with detoured traffic, the operators had to change the BGP routing policy. Despite the routing-level first aid, a few institutions could not be directly connected to the R&E network community because they had only a single link to the network. For these single-link networks, the commodity link was temporarily used for connectivity. Then, cable connection configurations at the switches were changed to provide high bandwidth and next-generation Internet service. From the whole restoration procedure, we learned that redundant BGP routing information is useful for recovering connectivity but not for providing available bandwidth for the re-routed traffic load and that collaboration between operators is valuable in solving traffic engineering issues such as poor-quality re-routing and lost connections of single-link networks.

Gridifying Neuroscientific Pipelines

Scipedia content — Mon, 25 Jan 2021 10:22:20 +0100

In recent times, innovative new e-Infrastructures have materialized all around the globe to address the compelling and unavoidably increasing demand on computing power and storage capacity. All fields of science have entered an era of digital explosion and thus need to face it with appropriate and scalable instruments. Amongst centuryâs cutting-edge technologies, the grid has become a tangible candidate which several initiatives have harnessed and demonstrated the added value of. Turning the concept into a concrete solution for Neurosciences, the neuGRID project aims to establish a grid-based e-Infrastructure providing neuroscientists with a powerful tool to address the challenge of developing and testing new markers of neurodegenerative diseases. In order to optimize the resulting grid and to deliver a user-friendly environment, neuGRID has engaged the process of migrating existing imaging and data mining toolkits to the grid, the so-called gridification, while developing a surrounding service oriented architecture of agnostic biomedical utilities. This chapter reports on a preliminary analysis of the issues faced in the gridification of neuroimaging pipelines and attempts to sketch an integration model able to cope with the several and heterogeneous applications used by neuroscientists.