Scipedia: Documents published in 2013

Effects of altitude on the soot emission and fuel consumption of a light-duty diesel engine

Scipedia content — Tue, 23 Mar 2021 06:13:34 +0100

four-cylinder, direct-injection (DI) diesel engine was used to study the effects of altitude on the variations of the exhaust soot emission and engine performance. The experiments were conducted in Mashhad, Iran, at an altitude of 975 m above sea level. A three-lobe rotary blower of Roots type was employed in order to simulate the altitudes down to 350 m by increasing the inlet manifold pressure of the engine. The tests were performed based on the ECE-R49 test cycle, and for each testing point, the experiments were repeated for five boosting pressures which correspond to five different altitudes. Results indicate that with increasing the altitude from 350 m to 975 m, the soot emission increases about 40%. This increase is due to the relatively lower the air density introduced into the cylinders in higher altitudes that leads to the increase of autoignition delay time which could shorten the late combustion phase; hence, the soot burnout process deteriorates. Also it was found that at low engine loads, the Brake-Specific Fuel Consumption (BSFC) increases about 20% with raising the altitude from 350 m to 975 m. At higher loads, the raising rate of fuel consumption is insignificant. The effects of altitude on the other engine parameters such as induced air mass flow rate, volumetric efficiency, equivalence ratio, and exhaust temperature were investigated as well. In addition, a sensitivity analysis was conducted and the results revealed that among the engine parameters, the soot emission alteration has the most sensitivity to the change of the altitude. First Published Online: 16 Jul 2013

Document type: Article

Private household demand for vehicles on alternative fuels and drive trains: a review

Scipedia content — Tue, 23 Mar 2021 06:03:33 +0100

ny attempt of the government to encourage the purchase of vehicles on alternative fuels and drive trains will depend on the acceptance of the end-users on the demand side. This paper offers an in-depth understanding of the consumers’ attitudes and preferences towards AFVs which can guide the government to establish effective policy measures. A comprehensive review of research is performed under different conceptual frameworks and research methodologies: attitudinal, experimental, preference valuation studies and others. Research findings are reported with the general objective to (1) uncover the attitudes and preferences towards AFVs and (2) examine whether the environmental benefits of AFVs play a role in the car purchase decision. Overall, there exists a strong environmental concern, and positive attitudes towards AFVs. However, environmental benefits are of little importance in the car purchase decision, which is principally driven by price characteristics, performance and convenience attributes. Limited knowledge levels also seem to prevent building up awareness of AFVs, which is the key to their adoption. The adoption of AFVs is likely to be limited without significant governmental incentives and regulations. Based on the key findings, it can be recommended that a combination of educational campaigns (e.g., information tools), pricing measures (e.g., differentiated vehicle taxation), supply-sided measures and large-scale demonstrations is required to support the adoption of AFVs.

Document type: Article

Mitigation Techniques to Reduce the Impact of Wind Turbines on Radar Services

Scipedia content — Tue, 23 Mar 2021 03:57:51 +0100

Radar services are occasionally affected by wind farms. This paper presents a comprehensive description of the effects that a wind farm may cause on the different radar services, and it compiles a review of the recent research results regarding the mitigation techniques to minimize this impact. Mitigation techniques to be applied at the wind farm and on the radar systems are described. The development of thorough impact studies before the wind farm is installed is presented as the best way to analyze in advance the potential for interference, and subsequently identify the possible solutions to allow the coexistence of wind farms and radar services.

Document type: Article

OpenFab: A programmable pipeline for multi-material fabrication

Scipedia content — Tue, 23 Mar 2021 02:41:32 +0100

3D printing hardware is rapidly scaling up to output continuous mixtures of multiple materials at increasing resolution over ever larger print volumes. This poses an enormous computational challenge: large high-resolution prints comprise trillions of voxels and petabytes of data and simply modeling and describing the input with spatially varying material mixtures at this scale is challenging. Existing 3D printing software is insufficient; in particular, most software is designed to support only a few million primitives, with discrete material choices per object. We present OpenFab, a programmable pipeline for synthesis of multi-material 3D printed objects that is inspired by RenderMan and modern GPU pipelines. The pipeline supports procedural evaluation of geometric detail and material composition, using shader-like fablets, allowing models to be specified easily and efficiently. We describe a streaming architecture for OpenFab; only a small fraction of the final volume is stored in memory and output is fed to the printer with little startup delay. We demonstrate it on a variety of multi-material objects.

National Science Foundation (U.S.) (Grant CCF-1138967)

National Science Foundation (U.S.) (Grant IIS-1116296)

United States. Defense Advanced Research Projects Agency (Grant N66001-12-1-4242)

National Science Foundation (U.S.). Graduate Research Fellowship

Massachusetts Institute of Technology. Undergraduate Research Opportunities Program

Document type: Article

Dynamic user equilibrium in public transport networks with passenger congestion and hyperpaths

Scipedia content — Tue, 23 Mar 2021 02:39:41 +0100

This paper presents a dynamic user equilibrium for bus networks where recurrent overcrowding results in queues at stops. The route-choice model embedded in the dynamic assignment explicitly considers common lines and strategies with alternative routes. As such, the shortest hyperpath problem is extended to a dynamic scenario with capacity constraints where the diversion probabilities depend on the time at which the stop is reached and on the expected congestion level at that time. In order to reproduce congestion for all the lines sharing a stop, the Bottleneck Queue Model with time-varying exit capacity, introduced in Meschini et al. (2007), is extended. The above is applied to separate queues for each line in order to satisfy the First-In-First-Out principle within every attractive set, while allowing overtaking among passengers with different attractive sets but queuing single file. The application of the proposed model to a small example network clearly reproduces the formation and dispersion of passenger queues due to capacity constraints and thus motivates the implementation of the methodology on a real-size network case as the next step for future research.

Document type: Article

Issues of eLogistics applications for varying stakeholders: findings from an online survey

Scipedia content — Mon, 22 Mar 2021 22:23:25 +0100

The current paper aims to: a) propose and verify definition of eLogistics: ‘a set of activities based on using ICT systems and tools, as well as the Internet, as the main communication medium in order to maintain logistics processes’ and explore its acceptance; b) provide a synthesis of trend and possibilities of eLogistics systems and c) obtain a comprehensive picture of available eLogistics applications, sources, functionality and use by different type of companies. A qualitative research approach was adopted applying the Bristol Online Survey (BOS) tool. A brief literature review (of limited online sources and books) resulted in the online survey questionnaire. The survey questions had the options of: agree or disagree; or yes or no on a particular statement or issue. Also to solicit the opinion of the survey participants, a free text area/box was provided against an issue or statement. The study suggests that open source, open standards and standardised system interfaces will support increased supply chain efficiency through integration and access to SMEs as well as larger players. The development and running of an eLogistics platform is costly for SMEs. The authors recommend that such platform be developed through funding by national governments and/or the European Commission. The running and maintenance of such platform can be done by an association relevant to SMEs or a third party with a small contribution (or fee) by the participating SMEs.

Document type: Article

Multiobjective Optimization Model of Residential Spatial Distribution

Scipedia content — Mon, 22 Mar 2021 21:26:21 +0100

The concept of jobs-housing balance has been adopted as an effective way to alleviate the traffic congestion, especially in metropolis. A multiobjective model of residential spatial distribution (MOOMRSD) is developed in this paper to address the problem of how to locate the housing in a reasonable way when the workplace location is given. Three objectives are integrated into the MOOMRSD and they are (1) minimizing the average commute cost from residence to workplace; (2) minimizing the total travel time of citizens; and (3) maximizing the aggregate utility and social benefit. In addition, a multiobjective genetic algorithm (MOGA) is proposed to figure out a satisfactory solution to the MOOMRSD. Finally, Both MOOMRSD and MOGA are applied into two cases.

Document type: Article

Uncovering Spatio-Temporal Cluster Patterns Using Massive Floating Car Data

Scipedia content — Mon, 22 Mar 2021 21:00:58 +0100

In this paper, we explore spatio-temporal clusters using massive floating car data from a complex network perspective. We analyzed over 85 million taxicab GPS points (floating car data) collected in Wuhan, Hubei, China. Low-speed and stop points were selected to generate spatio-temporal clusters, which indicated the typical stop-and-go movement pattern in real-world traffic congestion. We found that the sizes of spatio-temporal clusters exhibited a power law distribution. This implies the presence of a scaling property

i.e., they can be naturally divided into a strong hierarchical structure: long time-duration ones (a low percentage) whose values lie above the mean value and short ones (a high percentage) whose values lie below. The spatio-temporal clusters at different levels represented the degree of traffic congestions, for example the higher the level, the worse the traffic congestions. Moreover, the distribution of traffic congestions varied spatio-temporally and demonstrated a multinuclear structure in urban road networks, which suggested there is a correlation to the corresponding internal mobile regularities of an urban system.

Document type: Article

Port activity evolution: the initial impact of economic crisis on major Greek ports

Scipedia content — Mon, 22 Mar 2021 20:43:53 +0100

The objective of this study is the quantitative analysis of recent developments in transport activity of the main Greek ports (Piraeus, Thessaloniki, Patra), in order to establish clusters of various transport load and time groups of growth and decline of the transport activity, regarding the period 2002–2010. From this latter approach, the investigation of any impact of the economic crisis in the evolution of transport activity can be explored. The methodology used is based on forming clusters, to identify growth-recession periods, and groups of determining transport categories. Methods used are: Principal Component Analysis, Factor Analysis and Cluster Analysis. The results show that the major port of Piraeus activity’s evolution can be represented by two distinct periods. A growth period (2002–2004) which is related to the Olympic Games of 2004 and an instability period of the transport activity’s evolution, which follows. The last 3 years a decrease for most of the transport activities has been encountered, due to the economic crisis. Considering the three main ports of the country, as a unit we realize a slightly differentiated picture, since, despite a distinct last period of decline, we cannot certainly shape the claim that during the previous years there is a strong positive influence in the other two ports by a developmental event like the Olympic Games. These findings could mean that the spatial developmental impact of the Olympic Games limited at the regional level. However the main findings for the Piraeus’ port, mentioned beforehand, are still valid. A general conclusion, regarding the prerequisites of the increased competitiveness and efficiency of ports, refers to the investments in modern infrastructure, services and systems administration, the transport management in Greek ports and the development of a combined transport system.

Document type: Article

The Reflective Cracking in Flexible Pavements

Scipedia content — Mon, 22 Mar 2021 20:37:03 +0100

Reflective cracking is a major concern for engineers facing the problem of road maintenance and rehabilitation. The problem appears due to the presence of cracks in the old pavement layers that propagate into the pavement overlay layer when traffic load passes over the cracks and due to the temperature variation. The stress concentration in the overlay just above the existing cracks is responsible for the appearance and crack propagation throughout the overlay. The analysis of the reflective cracking phenomenon is usually made by numerical modeling simulating the presence of cracks in the existing pavement and the stress concentration in the crack tip is assessed to predict either the cracking propagation rate or the expected fatigue life of the overlay. Numerical modeling to study reflective cracking is made by simulating one crack in the existing pavement and the loading is usually applied considering the shear mode of crack opening. Sometimes the simulation considers the mode I of crack opening, mainly when temperature effects are predominant.

Document type: Article

The connectivity of South Asian cities in infrastructure networks

Scipedia content — Mon, 22 Mar 2021 20:13:01 +0100

This map summarizes information on the connectivity of 67 important South Asian cities concerning infrastructure networks. The map combines four information layers to reveal a city's overall stature in the region's infrastructure networks, i.e. rail, road, air, and information technology networks. Three dimensions of connectivity are shown: edge thickness reflecting tie strength between pairs of cities; node size reflecting a city's betweenness centrality; and node color reflecting the dominant geographical orientation of a city's connections. A threshold is used for the edges to ensure the map does not appear clogged. The map shows that major connections tend to be within-country linkages between large cities. There are five communities in South Asia's urban infrastructure networks, which largely follow national borders. Delhi, Mumbai, Lahore, Karachi, Chennai, Colombo and Dhaka are shown to be important nodes for the infrastructural integration of South Asia, as these cities mediate flows between relatively unconnected communities and cities.

Document type: Article

Ship Trajectory Control Optimization in Anti-collision Maneuvering

Scipedia content — Mon, 22 Mar 2021 19:52:31 +0100

lot of attentions are being paid to ship's intelligent anti-collision by researchers. Several solutions have been introduced to find an optimum trajectory for ship, such as Game Theory, Genetic or Evolutionary Algorithms and so on. However, ship's maneuverability should be taken into consideration before their real applications. This paper focuses on ship's trajectory control problem in anti-collision maneuvering. At first, a simple linear ship maneuverability model is introduced to simulate its movement under different speed and rudder angle. After that, ship's trajectory control is studied by considering the duration of rudder, operation distance to turning points, and maximum angular velocity. The details for algorithm design are also introduced. By giving some restrictions according to the requirements from COLREGs, the intervals for rudder angle in different circumstances can be determined by the curves. The results can give very meaningful guidance for seafarers when making decisions. Distributed under the terms of the Creative Commons Attribution License (CC BY-NC), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. For licence details please see http://creativecommons.org/licenses/by-nc/3.0

Document type: Article

Salários e empregos na indústria do transporte aéreo portuguesa

Scipedia content — Mon, 22 Mar 2021 19:46:23 +0100

Using a large matched employer-employee data set with information at both the worker and the company level we characterise the Portuguese airlines' employment structure and, by comparing it with the general structure of the Portuguese labour force, we stress the particularities of the sector. Based on the Heckman selection model, we develop an analysis of the variables that influence wages in this sector and which contribute to its differentiation from the general labour market. Particular attention is paid to the disparity among different types of jobs in the air transportation sector, namely amongst flight crews and land personnel. We also analyse the differences between regular and non-regular sub-sectors. Our main findings indicate that the aviation sector labour force is clearly specific regarding gender distribution and human capital accumulated by its workers. Moreover, some professions, pilots in particular, have important specificities compared to other jobs even within the sector. We also find that wages are strongly influenced by levels of education, tenure and experience as well as professional categories, which appears as an important specificity of this sector. Usando uma grande base de dados com correspondência empregador-empregado com informações tanto ao nível do trabalhador quanto da empresa, caracterizamos a estrutura de emprego das companhias aéreas portuguesas e, por meio de comparação com a estrutura geral da força de trabalho portuguesa, destacamos as particularidades do setor. Com base no modelo de seleção de Heckman, desenvolvemos uma análise das variáveis que influenciam os salários neste setor e que contribuem para a sua diferenciação do mercado de trabalho em geral. É dada atençao especial para a disparidade entre os diferentes tipos de empregos no setor de transporte aéreo, ou seja, entre os tripulantes e o pessoal de terra. Analisamos também as diferenças entre os subsetores de aviação regular e não-regular. Nossos principais resultados indicam que a força de trabalho no setor de aviação é claramente específica quanto à distribuição de gênero e de capital humano acumulado por seus trabalhadores. Além disso, algumas profissões, pilotos em particular, têm especificidades importantes em comparação com outros tipos de trabalhos, mesmo dentro do setor. Também apontamos para evidências de que os salários são fortemente influenciados pelos níveis de escolaridade, senioridade e experiência bem como pelas categorias profissionais, que aparecem como uma especificidade importante deste setor.

Document type: Article

Transferability of driver speed and lateral deviation measurable performance from semi-dynamic driving simulator to real traffic conditions

Scipedia content — Mon, 22 Mar 2021 19:42:23 +0100

Purpose This manuscript presents the experimental plan and results of driver trials conducted with a semi-dynamic driving simulator and an equipped research vehicle in real traffic conditions.

Document type: Article

Towards an Authoritative OpenStreetMap: Conflating OSM and OS OpenData National Maps’ Road Network

Scipedia content — Mon, 22 Mar 2021 19:15:49 +0100

The quality aspects of OpenStreetMap (OSM), as the global representation of crowd-sourced mapping, have always been of priomary concern to academics. While the methodologies for checking its quality against the national maps have been implemented by a number of studies, there are minimal works on how to practically improve the quality of OSM towards being an authoritative map source. This paper presents a method for conflating road attributes, namely the name and reference code, of OSM with the Open Data provided by Ordnance Survey (the British national mapping agency). The added values in the proposed methodology include the daily updates and serving of the conflated maps via open Web Services. More importantly, the OSM crowd correction is facilitated by frequently highlighting and web-serving the individual differences. There are currently over 5,800 differences in matching road names and references between the two datasets. In addition to describing the conflation methodology, the different geographic distribution patterns of the identified differences are discussed. A negative effect of the road density on the ratio of the mismatched features between the two datasets is observable, evidenced by their different geographical distribution over the map. It is shown that the best correspondence between attributes exists in the very dense areas, followed by the very low density areas, and lastly in the middle to large sized cities.

Document type: Article

Real-time monitoring of railway traffic using slope-assisted Brillouin distributed sensors

Scipedia content — Tue, 16 Feb 2021 13:21:28 +0100

The application of a Brillouin distributed sensor for the monitoring of railway traffic is presented in this work. The field test is performed on the Italian regional line San Severo–Peschici, operated by Ferrovie del Gargano. A single-mode optical fiber sensor was attached along a rail length of about 60 m. The strain associated with train passage was acquired along the monitored rail length at 31 Hz acquisition rate and 1 m spatial resolution. The data acquired by the sensor demonstrates its capability of retrieving useful information in railway traffic monitoring, such as train identification, axle counting, speed detection, and dynamic load calculation.

Energy saving in sliding vane rotary compressors using pressure swirl oil atomizers

Scipedia content — Tue, 16 Feb 2021 13:21:15 +0100

In industrial contexts, electrical energy for compressed air represents an important share of the global electricity consumption: this figure accounts for 4–5% of the total. Among the existing compressor technologies, rotary volumetric machines proved to be more suitable than other types (dynamic, reciprocating, etc.) in terms of pressure and flow rate delivered. Even though not as widespread as screw machines, but thanks to the technological improvements made in the last two decades, sliding vane rotary compressors are characterized by premium specific energy consumptions and demonstrate an unforeseen potential in terms of energy saving due to some intrinsic features specifically related to these machines. The current research focuses on an innovative oil injection technology that is not only able to fulfill the sealing and lubrication requirements but also to cool the air during the compression phase. A comparison between the mathematical model of the new oil injection technology and the experimental p-V diagrams measured through a set of piezoelectric transducers is shown. The compression work reduction, predicted in the model and further measured at the shaft and observed in the indicator diagrams, gives a strong consistency to the injection technology. The work has been done under the FP7 project ‘‘Complete Vehicle Energy-saving – CONVENIENT’’ funded by the European Commission.

ITETRIS: A modular simulation platform for the large scale evaluation of cooperative ITS applications

Scipedia content — Tue, 16 Feb 2021 13:19:47 +0100

Cooperative ITS systems are expected to improve road traffic safety and efficiency, and provide infotainment services on the move, through the dynamic exchange of messages between vehicles, and between vehicles and infrastructure nodes. The complexity of cooperative ITS systems and the interrelation between its components requires their extensive testing before deployment. The lack of simulation platforms capable to test, with high modelling accuracy, cooperative ITS systems and applications in large scale scenarios triggered the implementation of the EU-funded iTETRIS simulation platform. iTETRIS is a unique open source simulation platform characterized by a modular architecture that allows integrating two widely adopted traffic and wireless simulators, while supporting the implementation of cooperative ITS applications in a language-agnostic fashion. This paper presents in detail the iTETRIS simulation platform, and describes its architecture, standard compliant implementation, operation and new functionalities. Finally, the paper demonstrates iTETRIS large scale cooperative ITS evaluation capabilities through the implementation and evaluation of cooperative traffic congestion detection and bus lane management applications. The detailed description and implemented examples provide valuable information on how to use and exploit iTETRIS simulation potential.

Island accessibility challenges: Rural transport in the Finnish archipelago

Scipedia content — Tue, 16 Feb 2021 13:16:56 +0100

global trend in declining island populations is causing severe accessibility challenges for rural archipelago residents. Since waterways often provide the only viable connection between islands, the planning of ferry routes and capacities relative to prevailing population patterns is critical. In this paper, we present a case study of Pargas, a rural archipelago region in Southwestern Finland, which in many ways provides a typical example of current depopulation trends in archipelago regions. Owing to high maintenance costs, changing population patterns and transportation needs, the ferry network of Pargas has recently attracted attention in terms of planning and a perceived need to reduce costs. Still, compared to in-land transportation, few academic studies have explored this issue. Using methods adapted from urban and land-based transport studies and diverse datasets, we aim at identifying spatial discrepancies between population patterns and transport options in the peripheral archipelago and at determining how well the ferry network meets the needs of the permanent and seasonal population of the islands. Our results show that although the existing ferry network in general functions relatively well in relation to the population, spatial mismatches between transport opportunities and population patterns in some of the prominent islands are nevertheless evident. Because the economic vitality of the region depends on a well-functioning transportation network, this study offers suggestions for improving transportation services in the study area.

Concepts and techniques for integration, analysis and visualization of massive 3D point clouds

Scipedia content — Tue, 16 Feb 2021 13:16:03 +0100

Remote sensing methods, such as LiDAR and image-based photogrammetry, are established approaches for capturing the physical world. Professional and low-cost scanning devices are capable of generating dense 3D point clouds. Typically, these 3D point clouds are preprocessed by GIS and are then used as input data in a variety of applications such as urban planning, environmental monitoring, disaster management, and simulation. The availability of area-wide 3D point clouds will drastically increase in the future due to the availability of novel capturing methods (e.g., driver assistance systems) and low-cost scanning devices. Applications, systems, and workflows will therefore face large collections of redundant, up-to-date 3D point clouds and have to cope with massive amounts of data. Hence, approaches are required that will efficiently integrate, update, manage, analyze, and visualize 3D point clouds. In this paper, we define requirements for a system infrastructure that enables the integration of 3D point clouds from heterogeneous capturing devices and different timestamps. Change detection and update strategies for 3D point clouds are presented that reduce storage requirements and offer new insights for analysis purposes. We also present an approach that attributes 3D point clouds with semantic information (e.g., object class category information), which enables more effective data processing, analysis, and visualization. Out-of-core real-time rendering techniques then allow for an interactive exploration of the entire 3D point cloud and the corresponding analysis results. Web-based visualization services are utilized to make 3D point clouds available to a large community. The proposed concepts and techniques are designed to establish 3D point clouds as base datasets, as well as rendering primitives for analysis and visualization tasks, which allow operations to be performed directly on the point data. Finally, we evaluate the presented system, report on its applications, and discuss further research challenges.

Model-driven risk analysis of evolving critical infrastructures

Scipedia content — Tue, 16 Feb 2021 13:11:15 +0100

The protection and security of critical infrastructures are important parts of Homeland Defense. Adequate means for analyzing the security risks of such infrastructures is a prerequisite for properly understanding the security needs and for maintaining appropriate incident preparedness. Risk management is coordinated activities to direct and control an organization with regard to risk, and includes the identification, analysis and mitigation of unacceptable risks. For critical infrastructures consisting of interdependent systems, risk analysis and mitigation is challenging because the overall risk picture may be strongly affected by changes in only a few of the systems. In order to continuously manage risks and maintain an adequate level of protection, there is a need to continuously maintain the validity of risk models while systems change and evolve. This paper addresses these challenges by presenting an approach to model-driven security risk analysis of changing and evolving systems. The approach is a tool-supported method with techniques and modeling support for traceability of system changes to risk models, as well as the explicit modeling of the impact of changes on the current risk picture. The presented artifacts are exemplified and validated in the domain of air traffic management.

Design of Efficient Air-Conditioning Systems for Electric Vehicles

Scipedia content — Tue, 16 Feb 2021 13:10:39 +0100

[EN] Among all the auxiliary components in conventional and electric vehicles, air-conditioning (AC) systems present the highest energy consumption. In fully electrical vehicles (FEVs), the heating of the cabin becomes an additional challenge as there is less waste heat available. Therefore, a careful design of the air-conditioning system and of the operation strategies is necessary to reach a reasonable FEV autonomy without compromising the thermal comfort. This paper presents a tool for the design, analysis and optimization of an efficient air-conditioning system for an electric minibus. It consists of dynamic models of each component of the system that have been developed and fully validated individually. Finally, they have been coupled together to simulate the overall vehicle performance of the vehicle in MATLAB-SIMULINK. The core of the system is a water-to-water reversible heat pump with a variable speed compressor. The internal water loop connects the heat pump to the air-coolers inside the cabin while the external water loop is integrated within the heat rejection system of the power electronics. An automatic control system regulates the speed of the compressor, the blowers and the circulation pumps to reach thermal comfort. The power consumption has been analysed under different working conditions and control settings using the overall vehicle model. The latter is a powerful tool not only to design and select MAC equipment, but also to find the most efficient operation strategies. This work has been supported by the European Commission under the 7th European Community framework program as part of the ICE project “MagnetoCaloric Refrigeration for Efficient Electric Air-Conditioning”, Grant Agreement no. 265434.B. Torregrosa-Jaime acknowledges the Spanish Science and Innovation Ministry (Ministerio de Ciencia e Innovación) for receiving the Research Fellowship FPU ref. AP2010-2160. Torregrosa-Jaime, B.; Payá Herreo, J.; Corberán, JM. (2013). Design of Efficient Air-Conditioning Systems for Electric Vehicles. SAE International Journal of Alternative Powertrains. 2(2):291-303. https://doi.org/10.4271/2013-01-0864 S 291 303 2 2

Eye Metrics for Task-Dependent Automation

Scipedia content — Tue, 16 Feb 2021 13:07:13 +0100

Future air traffic is expected to grow increasingly, opening up a gap for task dependent automation and adaptive interfaces, helping the Air Traffic Controller to cope with fluctuating workloads. One of the challenging factors in the application of such intelligent systems concerns the question what the operator is doing in order to optimize support and minimize automation surprises. This study questions whether eye metrics are able to determine what task the operator is engages in. We therefore examined A) if the eye-path would differ for three different ATC tasks and B) whether this effect can be quantified with six eye-metrics. In an experiment, the six eye-metrics were calculated and used as a dependent variable. The results show that some tasks can be inferred by eye movement metrics and other metrics infer workload, although none inferred by both task and workload. Copyright 2014 ACM.

Sleep, Sleepiness, and Neurobehavioral Performance While on Watch in a Simulated 4 Hours on/8 Hours off Maritime Watch System

Scipedia content — Tue, 16 Feb 2021 13:04:31 +0100

Seafarer sleepiness jeopardizes safety at sea and has been documented as a direct or contributing factor in many maritime accidents. This study investigates sleep, sleepiness, and neurobehavioral performance in a simulated 4 h on/8 h off watch system as well as the effects of a single free watch disturbance, simulating a condition of overtime work, resulting in 16 h of work in a row and a missed sleep opportunity. Thirty bridge officers (age 30 +/- 6 yrs; 29 men) participated in bridge simulator trials on an identical 1-wk voyage in the North Sea and English Channel. The three watch teams started respectively with the 00-04, the 04-08, and the 08-12 watches. Participants rated their sleepiness every hour (Karolinska Sleepiness Scale [KSS]) and carried out a 5-min psychomotor vigilance test (PVT) test at the start and end of every watch. Polysomnography (PSG) was recorded during 6 watches in the first and the second half of the week. KSS was higher during the first (mean +/- SD: 4.0 +/- 0.2) compared with the second (3.3 +/- 0.2) watch of the day (p

An Algorithm for Managing Aircraft Movement on an Airport Surface

Scipedia content — Tue, 16 Feb 2021 12:58:55 +0100

The present paper focuses on the development of an algorithm for safely and optimally managing the routing of aircraft on an airport surface in future airport operations. This tool is intended to support air traffic controllersâ€™ decision-making in selecting the paths of all aircraft and the engine startup approval time for departing ones. Optimal routes are sought for minimizing the time both arriving and departing aircraft spend on an airport surface with engines on, with benefits in terms of safety, efficiency and costs. The proposed algorithm first computes a standalone, shortest path solution from runway to apron or vice versa, depending on the aircraft being inbound or outbound, respectively. For taking into account the constraints due to other traffic on an airport surface, this solution is amended by a conflict detection and resolution task that attempts to reduce and possibly nullify the number of conflicts generated in the first phase. An example application on a simple Italian airport exemplifies how the algorithm can be applied to true-world applications. Emphasis is given on how to model an airport surface as a weighted and directed graph with non-negative weights, as required for the input to the algorithm.

Document type: Article

Modelling three-phase releases of carbon dioxide from high-pressure pipelines

Scipedia content — Tue, 16 Feb 2021 12:53:44 +0100

This paper describes the development and experimental validation of a three-phase flow model for predicting the transient outflow following the failure of pressurised CO2 pipelines and vessels. The choked flow parameters at the rupture plane, spanning the dense-phase and saturated conditions to below the triple point, are modelled by maximisation of the mass flowrate with respect to pressure and solids mass fraction at the triple point. The pertinent solid/vapour/liquid phase equilibrium data are predicted using an extended Peng–Robinson equation of state. The proposed outflow model is successfully validated against experimental data obtained from high-pressure CO2 releases performed as part of the FP7 CO2PipeHaz project (www.co2pipehaz.eu). The formation of solid phase CO2 at the triple point is marked by a stabilisation in pressure as confirmed by both theory and experimental observation. For a fixed diameter hypothetical pipeline at 100 bar and 20 °C, the flow model is used to determine the impact of the pipeline length on the time taken to commence solid CO2 discharge following its rupture.

Globalization and sustainable development: Case study on international transport and sustainable development

Scipedia content — Tue, 16 Feb 2021 12:50:23 +0100

This article assesses the potential contribution for international shipping and long-haul aviation to contribute to sustainable development (SD). The trade literature shows that newly industrializing countries are benefitting from international trade for export-led growth. However, the least developed countries with limited access to international trade networks do not participate in the new global production networks. The World Trade Organization/General Agreement on Tariffs and Trade and Intergovernmental Panel on Climate Change regimes do not have the development of more sustainable transport systems as a priority. In this sense, international transport remains on the fringes of the environment and development policy fields. Three transition pathways to SD have been developed: (a) information and telecommunications technologies leading to participation of least developed countries in global production networks, (b) changes in social preferences toward a high priority for the environment, leading to an extensive growth in fair-trade networks and sustainable production and consumption, and (c) SD from economic growth in newly industrializing countries, with an increased priority placed on solving environmental problems.

Oblique impact of a smooth body on a thin layer of inviscid liquid

Scipedia content — Tue, 16 Feb 2021 12:50:06 +0100

The two-dimensional motion of a rigid body with a smooth surface is studied during its oblique impact on a liquid layer. The problem is coupled: the three degrees of freedom of the moving body are determined together with the liquid flow and the hydrodynamic pressure along the wetted part of the body surface. The impact process is divided into two temporal stages. During the first stage, the wetted region expands at a high speed with jetting flows at both ends of the wetted region. In the second stage, the free surface of the liquid is allowed to separate from the body surface. The position of the separation point is determined with the help of the Brillouin–Villat condition. Calculations are performed for elliptic cylinders of different masses and with different orientations and speeds before the impact. The horizontal and vertical displacements of the body, as well as its angle of rotation and corresponding speeds are investigated. The model developed remains valid until the body either touches the bottom of the liquid or rebounds from the liquid.

0-1 integer programming model for procedural separation of aircraft by ground holding in ATFM

Scipedia content — Tue, 16 Feb 2021 12:48:27 +0100

WOS: 000334486400001

This study presents a 0-1 integer programming model for air traffic flow management. The model is used for determining optimum departure times of aircraft so as to avoid aircraft conflicts and to balance capacity and demand on the airports. Standard air traffic control procedural separation minimas were set as conflict criteria, which has never been done before, and this makes it convenient for use in planning of flows in airspace sectors especially without surveillance system. The model was tested on an imaginary scenario, including an airspace sector, airport capacities and flight plans, and solved by a mathematical modelling and optimization software. Considering conflicts before takeoff, as in this study, might prevent riskier and costlier air traffic control measures such as heading, speed and flight level changes. The great need for these measures can be easily inferred from the solution results that presents delay times due to conflict related constraints. Utilizing both standard conflict criteria based on procedural separation minimas used in air traffic control and standard Air Traffic Flow Management strategy based on ground holding of aircraft in planning of flows, makes it easier to adapt the model to the current Air Traffic Flow Management system

Early warning and mass evacuation in coastal cities

Scipedia content — Tue, 16 Feb 2021 12:47:31 +0100

The FP7 Theseus research project (2009–2013) aims to develop and assess innovative technologies and methodologies for coastal protection against erosion, flooding and environmental damages. While protection structures may help to reduce the level of hazard and the expected degree of loss, some danger of technical failures or human errors will always remain. For extreme events, the implementation of non-structural measures as early warning systems and disaster management practices is required to ensure the protection of population. During Theseus, a methodology for helping the local authorities to prepare an action plan in case of coastal flooding was developed and tested on the estuary of Gironde in France. The methodology builds over the return of experience from past events and tries to clearly identify all the stages of an evacuation and the thinking process that can lead to a robust evacuation plan. It relies on a conceptual framework – SADT – which helps to understand how data should be processed from its collection to its use in the plan. The risk scenarios were calculated for current and future conditions of the XXIst century, taking into account the effects of climate change. The methodology is supported by the OSIRIS software, prototyped during the FP5 eponymous project and later distributed by CETMEF and the French basin authorities of Loire and Meuse. The methodology for the preparation of evacuation plans was applied on a pilot city of Theseus, Bordeaux on the estuary of Gironde (France), and the software used to calculate evacuation times was tried out on Cesenatico near the Adriatic coast (Italy). This comparison verified the replicability of methodological guidelines in two different European contexts. The cultural and organizational differences and the different number of people involved underlined strong questions to be addressed when applying them. In order to assess the efficiency of an evacuation strategy and to compute the number of people successfully evacuated over time, a macroscopic model (not representing each individual vehicle but only flows of vehicles in congestion points) for the simulation of traffic congestion was used, based on the work of the University of Twente, Rijkswaterstaat and INFRAM. This model will be integrated in the Theseus decision support system for helping coastal managers to select their strategy for risk mitigation.

Take-off aided by magnetic levitation technology

Scipedia content — Tue, 16 Feb 2021 12:44:49 +0100

Purpose – The purpose of the paper is to analyze changes in the selected characteristics of an aircraft aided by a ground-based system using magnetic levitation (MAGLEV) to support safe take-off. Design/methodology/approach – The analysis of the mass characteristics of the main aircraft units with conventional constructing solutions was carried out in this paper. It allowed determining the mass of these units and verifying the obtained results on the basis of the known examples. Thanks to such an approach it was possible to determine the mass of the aircraft modified for the requirements of the ground and on-board system for support of the aircraft safe take-off and landing (GABRIEL) system taking into account the change in the weights of the modified units (fuselage, wings, power unit, landing gear, etc.). The weight of the aircraft in its basic version was determined on the basis of the common knowledge and methods described in the scientific literature which are based on the statistical analysis. The w...

Reducing the risk of suicide or trespass on railways: developing better interventions through understanding behaviours of people

Scipedia content — Tue, 16 Feb 2021 12:44:04 +0100

Suicide and trespass are major problems for railway operators in Great Britain, leading to around 250–300 fatalities per year, as well as associated major disruption to the rail network. The Europe...

On multi-criteria sustainability assessment: Spider-gram surface and dependence biases

Scipedia content — Tue, 16 Feb 2021 12:43:04 +0100

Multi-criteria evaluation methods are often used for sustainability assessment. One such method is the Multi-criteria Spider-gram Cumulative Surface Area (MCSA score) recently used for this purpose (Nzila et al., Multi-criteria sustainability assessment of biogas production in Kenya. Applied Energy 93:496-506, 2012). This paper presents results illustrating that the MCSA method results and rankings might be biased by the arbitrary order of the criteria. This paper also addresses the way the comparison of two alternatives can be biased by the presence of a third (possibly irrelevant) alternative. Such dependence bias is due to the use of an internal normalization operation, a problem shared by some multi-criteria analysis methods. The paper concludes with a few suggestions to avoid such biases. © 2013 Elsevier Ltd.

A Panel Data Approach to Evaluate the Passenger Satisfaction of a Public Transport Service

Scipedia content — Tue, 16 Feb 2021 12:40:33 +0100

In the present work we analyze the passenger satisfaction of a public transport service by means of a panel data approach. Improving the quality and efficiency of public transport is important if we are to change the daily transport habits of the public. The congestion in urban areas and its immediate and wider consequences on the climate are pushing central and local governments to instigate sustainable transport policies. These policies require an ever more personalised attention to the desires of the customer, to know and quantify the most influential variables on their decision to travel in public transport. The quality of a public transport system is covered by many factors, such as considerations relative to comfort and safety within the vehicle, the time taken to cover the routes and the convenience and existence of any supporting infrastructure. The techniques that we have used to analyse the panel data are: fixed effects and random effects.

ITS-based Cooperative Services development framework for improving safety of vulnerable road users

Scipedia content — Tue, 16 Feb 2021 12:37:48 +0100

Innovative advanced systems have been proposed for improving the safety and efficiency in the mobility of road users in Europe. Particularly for road transport, new ITS-based Cooperative Services for preventing accidents in critical points and situations are emerging where road users, vehicles and a sensorised integrative infrastructure are the main actors. With this motivation, and taking into account the road infrastructure's capability to incorporate new Cooperative Systems technology, this study aims to provide a first set of guidelines for speeding up the convergence process among a broad set of multi-heterogeneous sensor data fusion, high level situation understanding and assessment, and communications capabilities, all of them necessary for the development of advanced ITS safety-related services previously mentioned. Analysis is focused on vulnerable road users (VRUs) and on how this kind of services will contribute to provide more intelligent and safer urban traffic environments. A typical scenario involving VRU is studied as a preliminary analysis of the impact that these systems have on the safety of a specific group of road users. Some of the underlying principles of the proposed architecture will be validated in a field operational test FP7 European project.

Leak detection of CO2 pipelines with simple atmospheric CO2 sensors for carbon capture and storage

Scipedia content — Tue, 16 Feb 2021 12:36:29 +0100

This paper presents a field test performed with five relatively simple CO2 sensors (Vaisala Carbocap GMP343) that were placed for more than one year in a field in Ten Post, Groningen, The Netherlands. Aim was to investigate their potential use in monitoring pipelines transporting CO2 for carbon capture and storage. All sensors react differently on temperature changes which decreased signal to noise ratio for this application. The detection limit for leak detection was improved by a factor of 2.5 (the standard deviation of the average difference between two sensors decreased from 10 ppm to 4 ppm) with either laboratory or field data correction. Using laboratory calibration, the sensor drift requires that temperature response and calibration have to be re-established about every three to six months. Using field data for calibration is less expensive and labor-intensive, but has also several drawbacks, like the requirement of sufficient variability of the atmospheric parameters during the calibration period and the risk of "correcting" an actual leak during cross calibration. A release test of CO2 showed that a leak of "3 g/s would be easily detectable with sensors placed in a 70 m grid. (C) 2013 Elsevier Ltd. All rights reserved.

An exploratory analysis of the effects of modal split obligations in terminal concession contracts

Scipedia content — Tue, 16 Feb 2021 12:36:05 +0100

The port authority of Rotterdam has been the first to incorporate modal split obligations in concession contracts for container terminals. Given the increasing focus of port authorities on sustainable hinterland connectivity, other port authorities may also move in this direction. A reduced share of road transport in the modal split can increase competitiveness in the hinterland, secure better levels of road accessibility and reduce the carbon footprint of hinterland transport. Through in-depth interviews with the three major terminal operating companies in Rotterdam, this paper explores the effects of modal split obligations. The impact of modal split obligations in concession contracts ranges from an impact solely on terminal design to an effect on the business model that terminal operating companies apply in a specific port.

Experimental investigation of the effect of 90° standard elbow on horizontal gas–liquid stratified and annular flow characteristics using dual wire-mesh sensors

Scipedia content — Tue, 16 Feb 2021 12:29:49 +0100

Fluid flowing through pipelines often encounters fittings such as elbows. Although it is true that two-phase flow patterns observed in elbows are qualitatively the same as those seen in straight pipes, the presence of a pipe elbow can modify relative positions and local velocities of the two phases as they are subjected to forces in addition to those encountered in a straight pipe. That redistribution can affect pressure drop values, chemical inhibitor concentration and distribution to the top of the pipe, as well as the erosion pattern occurring from solid particles such as sand that is entrained in oil and gas transportation pipelines. In this work, a wire-mesh sensor technique based on conductance measurements of void fraction was applied to investigate two-phase pipe flow through a standard elbow. The horizontal flow test section, consisting of a 76.2 mm ID, 18 m long pipe, was employed to generate stratified-wavy and annular flow conditions. Two 16 × 16 wire-mesh configuration sensors were positioned either 0.9 m upstream or 0.6 m downstream of the bend. The experiments were conducted at superficial liquid velocities equal to 0.03 m/s and 0.2 m/s and superficial gas velocities that ranged from 9 m/s to 34 m/s. The effects of liquid viscosity on the measured parameters are also investigated using two different viscosities of 1 and 10 cP. Stratified–slug transition, stratified wavy and annular flow patterns were observed visually in the clear section placed upstream of the wire-mesh sensors. Analysis of time series void fraction data from the dual wire-mesh sensors allows the determination of mean void fraction, local time average void fraction distribution, liquid phase distribution around the tube periphery, interfacial structure velocities, as well as probability density function characteristic signatures within the cross-section of pipe before and after the elbow. The results indicate that the distribution of gas and liquid phases and interfacial velocities are significantly altered even 20 diameters downstream of the elbow.

Ecodriving acceptance : an experimental study on anticipation behavior of truck drivers

Scipedia content — Tue, 16 Feb 2021 12:27:29 +0100

In this paper, it is researched to what extend truck drivers are willing to improve their anticipation behavior. For the purpose of this research, anticipation behavior is characterized by anticipation distance: the distance to a stopping point (e.g. roundabout), at which the accelerator pedal is released. A larger anticipation distance yields a lower fuel consumption. The goal of this research was to reveal the potential anticipation improvement without exceeding driver’s acceptance. Therefore, the driver’s natural anticipation distance, and the acceptance of prescribed distance was measured. The effects of this improved behavior, in terms of saved fuel and additional trip time, are analyzed. The analysis suggested that improved anticipation behavior can save up to 98 grams of fuel per deceleration event. Finally, natural driving behavior on public roads was measured as a baseline. By projecting the potential anticipation improvements on this baseline measurement, a potential fuel consumption reduction of 9.5% at the cost of 4.6% additional trip time was found. Overall, the current research suggested that truck drivers are willing to improve their anticipation behavior, and that this improvement can lead to substantial fuel consumption reduction. Furthermore, it was found that the potential fuel savings are often limited by visibility. This suggests a potential for GPS-based driver support systems which can help the driver to enhance their anticipation behavior even further.

Long-haul specialization patterns in European multihub airline networks: An exploratory analysis

Scipedia content — Tue, 16 Feb 2021 12:21:41 +0100

Multihub airline networks are an important phenomenon in today's air transport market. An important question is to what extent different factors play a role in the specialization between hubs that are part of the same multihub network. This paper shows that total European market size to a certain long-haul destination and the ratio between the origin-destination market at the primary and the secondary hub are important variables for the role hubs play in the long-haul network of European multihub systems. Large long-haul markets are generally served from both the primary and secondary hub. Multihub carriers serve smaller long-haul markets uniquely from a single hub, depending on the relative advantage in the local origin-destination market. Looking at actual specialization patterns within European multihub networks, we distinguish between complementary multihub systems (such as Amsterdamâ€“Paris CDG), overflow systems (such as Frankfurtâ€“Munich) and regional systems (such as Paris CDGâ€“Lyon).

Impact of inland shipping emissions on elemental carbon concentrations near waterways in The Netherlands

Scipedia content — Tue, 16 Feb 2021 12:18:19 +0100

This study aims to quantify the impact of black carbon from inland shipping on air quality, expressed as elemental carbon (EC) near inland waterways in The Netherlands. Downwind measurements of particle numbers and EC were used to establish emission factors for EC from inland shipping using inverse modelling. These emission factors were combined with data on energy consumption to derive annual average emissions rates for all Dutch waterways. A line source model was applied to compute the contribution of inland shipping to annual average EC concentrations for around 140,000 people living within 200m of busy waterways in The Netherlands. The results showed that they are exposed to additional EC concentrations of up to 0.5μgEC per m3 depending on the shipping volume and distance from the waterway. In view of the envisaged growth in water transport, this underlines the need to reduce combustion emissions from inland shipping. Targeting "gross" polluters may be the most effective approach since 30% of ships cause more than 80% of the total emissions. © 2014 Elsevier Ltd.

Optimizing itineraries in public transportation with walks between rides

Scipedia content — Tue, 16 Feb 2021 12:17:16 +0100

We study the problem of finding an optimal itinerary to travel from a starting location to a destination location using public transport, where we allow travelers to alternate rides with (short) walks. The main difference with previous research is that we take all possible walks that a traveler can make into consideration. This large number of possible walks poses a potential computational difficulty. However, in this paper we derive theorems for identifying a small subset of walks that only need to be considered. These results are embedded in a solution algorithm, which is tested in a real-life setting for bus transportation in a medium sized city. An extensive numerical study leads to encouraging results. First, only 1% of all possible walks needs to be considered, so that the optimal itinerary can be determined very efficiently. Second, allowing walks has considerable benefits; reducing the travel time in about 6% of all randomly generated examples by more than 10% on average. (C) 2013 Elsevier Ltd. All rights reserved.

Air Flows in Gravity Sewers - Determination of Wastewater Drag Coefficient

Scipedia content — Tue, 16 Feb 2021 12:15:02 +0100

Several experiments have been conducted in order to improve the understanding of the wastewater drag and the wall frictional force acting on the headspace air in gravity sewers. The aim of the study is to improve the data basis for a numerical model of natural sewer ventilation. The results of the study shows that by integrating the top/side wall shear stresses the log-law models for the air velocity distribution along the unwetted perimeter resulted in a good agreement with the friction forces calculated by use of the Colebrook-White formula for hydraulic smooth pipes. Secondly, the water surface drags were found by log-law models of the velocity distribution in turbulent flows to fit velocity profiles measured from the water surface and by integrating the water surface drags along the wetted perimeter, mean water surface drags were found and a measure of the water surface drag coefficient was found.

Visual Traffic Jam Analysis Based on Trajectory Data

Scipedia content — Tue, 16 Feb 2021 12:13:15 +0100

In this work, we present an interactive system for visual analysis of urban traffic congestion based on GPS trajectories. For these trajectories we develop strategies to extract and derive traffic jam information. After cleaning the trajectories, they are matched to a road network. Subsequently, traffic speed on each road segment is computed and traffic jam events are automatically detected. Spatially and temporally related events are concatenated in, so-called, traffic jam propagation graphs. These graphs form a high-level description of a traffic jam and its propagation in time and space. Our system provides multiple views for visually exploring and analyzing the traffic condition of a large city as a whole, on the level of propagation graphs, and on road segment level. Case studies with 24 days of taxi GPS trajectories collected in Beijing demonstrate the effectiveness of our system.

A linearized model of water exit

Scipedia content — Tue, 16 Feb 2021 12:12:47 +0100

A model of hydrodynamic loads acting on a rigid floating body during the lifting of the body from the liquid surface is presented. The liquid is of infinite depth, inviscid and incompressible. Initially the liquid is at rest. The body suddenly starts to move upwards from the liquid at a constant acceleration. Boundary conditions on the liquid surface are linearized and imposed on the equilibrium position of the liquid surface. The resulting boundary problem is solved by the methods of analytical functions. Negative pressures are allowed and the pressure is assumed continuous at the periphery of the wetted area. The unknown size of the wetted area is determined by the condition that the speed of the contact points is proportional to the local velocity of the flow. This condition provides a nonlinear Abel-type integral equation which is solved explicitly. Both two-dimensional and axisymmetric configurations are considered. Predicted hydrodynamic forces are compared with the computational fluid dynamics results by Piro & Maki ("jats:italic"11th International Conference on Fast Sea Transport. Honolulu, Hawaii, USA"/jats:italic", 2011) for both a rigid wedge and circular cylinder, which initially enter the water and then exit from it.

Modelling delay propagation within an airport network

Scipedia content — Tue, 16 Feb 2021 12:08:28 +0100

We describe an analytical queuing and network decomposition model developed to study the complex phenomenon of the propagation of delays within a large network of major airports. The Approximate Network Delays (AND) model computes the delays due to local congestion at individual airports and captures the " ripple effect" that leads to the propagation of these delays. The model operates by iterating between its two main components: a queuing engine (QE) that computes delays at individual airports and a delay propagation algorithm (DPA) that updates flight schedules and demand rates at all the airports in the model in response to the local delays computed by the QE. The QE is a stochastic and dynamic queuing model that treats each airport in the network as a M(t)/. Ek(t)/1 queuing system. The AND model is very fast computationally, thus making possible the exploration at a macroscopic level of the impacts of a large number of scenarios and policy alternatives on system-wide delays. It has been applied to a network consisting of the 34 busiest airports in the continental United States and provides insights into the interactions through which delays propagate through the network and the often-counterintuitive consequences. Delay propagation tends to " smoothen" daily airport demand profiles and push more demands into late evening hours. Such phenomena are especially evident at hub airports, where some flights may benefit considerably (by experiencing reduced delays) from the changes that occur in the scheduled demand profile as a result of delays and delay propagation. © 2011 Elsevier Ltd.

Detection of distributed deterioration in single pipes using transient reflections

Scipedia content — Tue, 16 Feb 2021 12:07:55 +0100

number of different methods that use signal processing of fluid transients (water hammer waves) for fault detection in pipes have been proposed in the last two decades. However, most of them focus solely on the detection of discrete deterioration, such as leaks or discrete blockages. Few studies have been conducted on the detection of distributed deterioration, such as extended sections of corrosion and extended blockages. This is despite the fact that they commonly exist and can have a severe negative impact on the operation of pipelines. The research reported here proposes a method of detecting distributed deterioration by investigating the time-domain water hammer response trace from a single pipe with a deteriorated section. Through wave analysis using a step pressure input, a theoretical square-shaped perturbation is found to exist in the transient pressure trace as a result of distributed deterioration. The hydraulic impedance of this section can be derived from the magnitude of the reflected pressure perturbation, while the location and length of the corresponding deteriorated section can be determined by using the arrival time and duration of the perturbation. The proposed method has been validated by analyzing experimental data measured from a pipe with a section of wall thickness change. Keywords: Pipelines, Fluid transients, Water distribution systems, Distributed deterioration, Extended blockages, Corrosion, Time-domain reflectometry

A simulation-based dynamic traffic assignment model with combined modes

Scipedia content — Tue, 16 Feb 2021 12:07:06 +0100

This paper presents a dynamic traffic assignment (DTA) model for urban multi-modal transportation network by constructing a mesoscopic simulation model. Several traffic means such as private car, subway, bus and bicycle are considered in the network. The mesoscopic simulator consists of a mesoscopic supply simulator based on MesoTS model and a time-dependent demand simulator. The mode choice is simultaneously considered with the route choice based on the improved C-Logit model. The traffic assignment procedure is implemented by a time-dependent shortest path (TDSP) algorithm in which travellers choose their modes and routes based on a range of choice criteria. The model is particularly suited for appraising a variety of transportation management measures, especially for the application of Intelligent Transport Systems (ITS). Five example cases including OD demand level, bus frequency, parking fee, information supply and car ownership rate are designed to test the proposed simulation model through a medium-scale case study in Beijing Chaoyang District in China. Computational results illustrate excellent performance and the application of the model to analysis of urban multi-modal transportation networks."/p" "p""strong" "/strong

Towards an urban planners’ perspective on Smart City

Scipedia content — Tue, 16 Feb 2021 12:06:53 +0100

The concept of “Smart City”, providing a solution for making cities more efficient and sustainable, has been quite popular in recent years, encouraging reflections, ideas, researches and projects for a “smart” urban development. A smart city is generally meant as a city capable of joining “competitiveness” and “sustainability”, by integrating different dimensions of development and addressing infrastructural investments able to support economic growth as well as the quality of life of communities, a more careful management of natural resources, a greater transparency and participation to decision-making processes. Based on those assumptions, this contribution tackle the controversial subject of Smart City, starting from the review of the scientific Italian and international literature that, from the Eighties to the Nineties, has been largely focused on ICTs and their impacts on urban development. Then, the focus shifts on the large debate on smart cities that has been developing from the beginning of 2000s and on the numerous institutional initiatives up to now implemented by the European Union for building up the Smart City. Finally, the article highlights how, despite these efforts, a shared definition of the term is still missing and current approaches to the issue are still very heterogeneous; it emphasizes, on the opposite, the key-role that urban planning, grounding on a holistic approach to cities’ development, should play in coordinating and integrating urban policies addressed to building up a Smart City.

Upgrading urban traffic flow by a demand-responsive fuzzy-based traffic lights model

Scipedia content — Tue, 16 Feb 2021 12:05:54 +0100

fuzzy model is proposed here to speed up traffic flows and reduce delay at road-signalized intersections by using real-time measures and traffic lights adaptation. The proposed demand-responsive control approach combines fixed-duration cycle and fuzzy calculus to reduce the overall delay without giving too much penalty to traffic streams. The traffic lights signal modification is based on the concept of “intersection saturation degree” that identifies the intersection performances. The numerical results of the proposed fuzzy approach confirm its better performances with respect to the other traditional control approaches.

The origin of ambient particulate matter concentrations in the Netherlands

Scipedia content — Tue, 16 Feb 2021 12:02:51 +0100

Particulate matter poses a significant threat to human health. To be able to develop effective mitigation strategies, the origin of particulate matter needs to be established. The regional air quality model LOTOS-EUROS, equipped with a newly developed labeling routine, was used to establish the origin of PM10 and PM2.5 in the Netherlands for 2007-2009 at the source sector level, distinguishing between national and foreign sources. The results suggest that 70-80% of modeled PM10 and 80-95% of PM2.5 in the Netherlands is of anthropogenic origin. About 1/3 of anthropogenic PM10 is of Dutch origin and 2/3 originates in foreign countries. Agriculture and transport are the Dutch sectors with the largest contribution to PM10 mass in the Netherlands, whereas the foreign contribution is more equally apportioned to road transport, other transport, industry, power generation and agriculture. For the PM2.5 fraction, a larger share is apportioned to foreign and anthropogenic origin than for PM10, but the same source sectors are dominant. The national contribution to PM levels is significantly higher in the densely populated Randstad area than for the country on average and areas close to the borders. In general, the Dutch contribution to the concentration of primary aerosol is larger than for secondary species. The sectoral origin varies per component and is location and time dependent. During peak episodes, natural sources are less important than under normal conditions, whereas especially road transport and agriculture become more important. © 2012 Elsevier Ltd.

A model of inbound air traffic : the application to Heathrow airport

Scipedia content — Tue, 16 Feb 2021 12:01:18 +0100

We present a model to describe the inbound air traffic over a congested hub and we show that this model gives a very accurate description of the traffic by comparing our theoretical distribution of the queue with the actual distribution observed at Heathrow airport. We also discuss the robustness of our model.

Effects of cooperative adaptive cruise control on traffic flow stability

Scipedia content — Tue, 16 Feb 2021 12:00:36 +0100

The effects of Cooperative Adaptive Cruise Control (CACC) on traffic flow is an important issue as traffic flow stability, capacity and safety are concerned. In contrast to most research we focus on traffic flow stability. We use the Intelligent Driver Model and CACC algorithms to assess the effects. A recently field-tested and CACC-based advisory system is also evaluated as an intermediate solution. It is found that CACC can quickly damp shockwaves at lower penetration rates (50%) and that shockwaves move faster. ©2010 IEEE.

Time-Domain Parameter Extraction Method for Thévenin-Equivalent Circuit Battery Models

Scipedia content — Tue, 16 Feb 2021 11:56:55 +0100

A transport carbon footprint methodology to assess airport carbon emissions

Scipedia content — Tue, 16 Feb 2021 11:56:42 +0100

orts are important nodes in the air transport system, but also local sources of environmental impacts. Emissions of CO2 are among the most relevant ones because of their potential greenhouse effects. Many policies and guidelines have been identified at national and world level to reduce such kind of impacts. In this paper, a Transport Carbon Footprint methodology has been set to identify Unit Carbon Footprints (UCFs) linked to some identified emission macro-sources – i.e., land vehicles, on-ground aircraft, airport handling and terminal equipment – to compute the contribution of the single macro-source to the total amount of CO2. Particularly, UCFs due to transport activities have been defined according to some relevant transport variables. The computation of UCF values for a given airport allows computing both the contribution of each macro-source and also evaluating the effectiveness of transport-related actions aiming at reducing the carbon impact. The methodology has been applied to the airport of Bologna, in Northern Italy, and its UCF values for the identified macro-sources have been computed.

Pushing CDN-ISP collaboration to the limit

Scipedia content — Tue, 16 Feb 2021 11:55:04 +0100

Today a spectrum of solutions are available for istributing content over the Internet, ranging from commercial CDNs to ISP-operated CDNs to content-provider-operated CDNs to peer-to-peer CDNs. Some deploy servers in just a few large data centers while others deploy in thousands of locations or even on millions of desktops. Recently, major CDNs have formed strategic alliances with large ISPs to provide content delivery network solutions. Such alliances show the natural evolution of content delivery today driven by the need to address scalability issues and to take advantage of new technology and business opportunities. In this paper we revisit the design and operating space of CDN-ISP collaboration in light of recent ISP and CDN alliances. We identify two key enablers for supporting collaboration and improving content delivery performance: informed end-user to server assignment and in-network server allocation. We report on the design and evaluation of a prototype system, NetPaaS, that materializes them. Relying on traces from the largest commercial CDN and a large tier-1 ISP, we show that NetPaaS is able to increase CDN capacity on-demand, enable coordination, reduce download time, and achieve multiple traffic engineering goals leading to a win-win situation for both ISP and CDN.

The potential of green gas in the Dutch transport sector

Scipedia content — Tue, 16 Feb 2021 11:48:04 +0100

In theory, green gas has the potential to become an attractive alternative for fossil fuels so as to contribute to the transport sector becoming more sustainable and environment-friendly. However, the large-scale implementation of green gas is hampered by many uncertainties. In this paper these uncertainties are assessed through on a series of SWOT analyses based on a study of the existing literature and inputs from stakeholders. The results of the SWOT analyses show that there are good prospects for the implementation of green gas in the longer run. The amount of green gas needed to replace the current fuel use of cars driving on diesel or petrol is huge, but it can be produced in an economically feasible way. For several specific markets, notably private cars, buses and trucks, it is found that green gas produced from landfill gas is profitable at least for private cars and may lead to relatively lower costs for the other two uses.

CO2 Transport Systems Development: Status of Three Large European CCS Demonstration Projects with EEPR Funding

Scipedia content — Tue, 16 Feb 2021 11:44:25 +0100

This paper addresses technical and operational aspects pertaining to the transport of CO2. It deals with lessons learnt from the development of three large CCS demonstration projects: the UK-based Don Valley project, the Dutch ROAD project, and the Spanish Compostilla project. These projects were all selected by the European Commission in 2009 to receive funding under the European Energy Programme for Recovery (EEPR). The purpose of the demonstration projects is to verify feasible capture techniques (i.e. gasification, flue-gas cleaning, and oxy-coal combustion in circulating fluidised bed, respectively), and to demonstrate geological storage options, off-shore and on-shore. As the distance and elevation of the CO2 transport system are inherently given by the project, the transport conditions for the CO2 will generally differ from one project to another.The demonstration projects have shown that the thermophysical nature of CO2 is prone to complicate certain operational procedures mainly due to phenomena like phase change, hydrate formation and Joule-Thomson cooling. The front-end engineering design studies suggest, however, that the handling of CO2 is quite feasible during normal operation, although customised solutions may be required to handle transients like emergency shut-down and pipeline re-pressurisation. This implies that CO2 transport is not seen as an insuperable hurdle to the design and operation of large CCS systems.

Continuous traffic flow modeling of driver support systems in multiclass traffic with inter-vehicle communication and drivers in the loop

Scipedia content — Tue, 16 Feb 2021 11:43:50 +0100

This paper presents a continuous traffic-flow model for the explorative analysis of advanced driver-assistance systems (ADASs). Such systems use technology (sensors and intervehicle communication) to support the task of the driver, who retains full control over the vehicle. Based on a review of different traffic-flow modeling approaches and their suitability for exploring traffic-flow patterns in the presence of ADASs, kinetic traffic-flow models are selected because of their good representation on both the aggregate level (congestion dynamics) and the level of the individual vehicle (vehicular interactions either directly or through intervehicle communication). The human-kinetic modeling approach is presented. It is a multiclass variant of kinetic traffic-flow models that is strongly based on individual driver behavior, i.e., on fully continuous acceleration/deceleration behavior and explicit modeling of the activation level of the driver. The strength of this modeling approach is illustrated by application to a driver-assistance system that uses intervehicle communication. It warns drivers when approaching sharp decelerations in a queue tail. The explorative analysis shows that the system results in safer and smoother transition from free-flowing to congested traffic. It also avoids compression of the queue tail, thus preventing the emergence of stop-and-go congestion patterns.

On analytical models of vertical water entry of a symmetric body with separation and cavity initiation

Scipedia content — Tue, 16 Feb 2021 11:42:55 +0100

Two-dimensional water entry with separation is investigated through different analytical models. This study focuses on the transient force acting on the body when the jet root detaches from the body surface and a cavity starts to develop behind the body. Logvinovich (1972) suggested a separation model in order to estimate the transient force acting on a finite wedge entering water. This model is revisited, developed further and assessed through comparison with more recent works on flow separation. The concept of Fictitious Body Continuation combined with the Modified Logvinovich Model is also investigated to estimate the transient drag during the initial stage of cavity formation. This model accounts for the variation in speed of the body during the separation stage. Several case studies are presented in order to show the relevance of this model. These include separation from chines and separation from smooth bodies.

Back and forward to the future : an explorative study of public responses to urban groundwater contaminations

Scipedia content — Tue, 16 Feb 2021 11:40:07 +0100

The objective of this case study is to explore responses by residents confronted with groundwater contamination in their community. Using a mail-survey design, self-administered questionnaires were collected (N = 170) that included questions about risk perceptions, site-specific concerns and perceived neighbourhood problems. The results show that concerns about chemical risks (i.e. chlorinated solvents) are rather limited in comparison to the potential impacts of site-redevelopment and other neighbourhood problems. Accordingly, the results of logistic regression analyses indicate that place detachment is not significantly related to risk perception but rather to site-specific concerns such as a perceived decrease in property values on the one hand, and wider environmental stressors such as traffic congestion on the other. In turn, the latter chronic environmental conditions are closely intertwined with residents views on the redevelopment of the contaminated site.

Water entry of a flat elastic plate at high horizontal speed

Scipedia content — Tue, 16 Feb 2021 11:35:12 +0100

The two-dimensional problem of an elastic-plate impact onto an undisturbed surface of water of infinite depth is analysed. The plate is forced to move with a constant horizontal velocity component which is much larger than the vertical velocity component of penetration. The small angle of attack of the plate and its vertical velocity vary in time, and are determined as part of the solution, together with the elastic deflection of the plate and the hydrodynamic loads within the potential flow theory. The boundary conditions on the free surface and on the wetted part of the plate are linearized and imposed on the initial equilibrium position of the liquid surface. The wetted part of the plate depends on the plate motion and its elastic deflection. To determine the length of the wetted part we assume that the spray jet in front of the advancing plate is negligible. A smooth separation of the free-surface flow from the trailing edge is imposed. The wake behind the moving body is included in the model. The plate deflection is governed by Euler’s beam equation, subject to free–free boundary conditions. Four different regimes of plate motion are distinguished depending on the impact conditions: ("jats:italic"a"/jats:italic") the plate becomes fully wetted; ("jats:italic"b"/jats:italic") the leading edge of the plate touches the water surface and traps an air cavity; ("jats:italic"c"/jats:italic") the free surface at the forward contact point starts to separate from the plate; ("jats:italic"d"/jats:italic") the plate exits the water. We could not detect any impact conditions which lead to steady planing of the free plate after the impact. It is shown that a large part of the total energy in the fluid–plate interaction leaves the main bulk of the liquid with the spray jet. It is demonstrated that the flexibility of the plate may increase the hydrodynamic loads acting on it. The impact loads can cause large bending stresses, which may exceed the yield stress of the plate material. The elastic vibrations of the plate are shown to have a significant effect on the fluid flow in the wake.

A cooperative systems based variable speed limit control algorithm against jam waves - an extension of the SPECIALIST algorithm

Scipedia content — Tue, 16 Feb 2021 11:32:10 +0100

The SPECIALIST algorithm can resolve jam waves on freeways using roadside technology: detector loops and speed limit gantries. In this paper we extend the algorithm, enabling the integration with cooperative system technologies and other road side detectors, such as in-car detection and actuation, and video-based monitoring (VBM). Integrating these cooperative elements can provide faster and more accurate jam detection, which leads to a better performance of the SPECIALIST algorithm. For the fusion of the various data sources (loops, VBM, floating car data) an extension of the Adaptive Smoothing Method is used. The data fusion method is also adapted to comply with the input requirements of the SPECIALIST algorithm. The resulting system is suitable for a mixed roadside/in-car detection and actuation environment. The performance of the resulting system is evaluated using the microscopic simulator VISSIM. The results show that floating car data and VBM can considerably improve the jam detection times and the accuracy of the detected jam location, which lead to more efficient speed limit schemes.

Capacity and delay analysis for airport manoeuvring areas using simulation

Scipedia content — Tue, 16 Feb 2021 11:31:02 +0100

WOS: 000330151300007

Purpose - The aim of this study is to identify the nodes where congestion occurs in the manoeuvring area of a large-scale airport and to provide appropriate suggestions for improvement. Design/methodology/approach - To investigate the air traffic flow in a highly complex system such as an airport manoeuvring area, a two-stage method based on fast- and real-time simulation techniques is applied. The first stage involves the analysis with fast- and real-time simulations of a baseline model created to determine the congestion points. Based on the analysis, improvements to be performed in the layout of the manoeuvring area are proposed. In the second stage, alternative scenarios implementing these improvements are generated and evaluated in a fast-time simulation environment. Based on the results of simulations of different runway configurations, the main areas of congestion in the baseline airport model are determined. Congestion nodes are identified in the departure queue points and in the taxiway system. To mitigate congestion at these points, three alternative models comprising taxiway and fast-exit taxiway reconfigurations are tested using the fast-time simulation technique. The alternative solution found to be the best in these tests is selected for further testing in real-time simulations. Findings - It is shown that the solution would result in an increase in the number of hourly operations and a significant decrease in total ground delays. When conducting the studies needed to identify congestion and design improvements, simulation techniques save both expense and time. Although fast-time simulations are usually adequate for identifying solutions, when critical configurations for the airport are considered, it is shown that it is necessary to also test the results of the fast-time simulations in real-time simulations. Research limitations/implications - The effects of meteorological events, such as rain, fog and snow, etc. are ignored in the simulations. Ground movements in manoeuvring areas are significantly affected by the runways used. Consequently, to enable a comprehensive evaluation in the study, three alternative runway use scenarios are examined. Originality/value - This study utilizes a combination of fast- and real-time simulation techniques to identify the points where congestion occurs in the manoeuvring areas of large-scale airports and to find solutions to minimize the congestion. This approach attempts to combine advantages of both techniques while reducing their shortcomings. No study is found in the literature using both of these techniques together for the capacity analysis of airport manoeuvring areas.

Anadolu University Scientific Research Projects Committee [BAP-1001F37]

This study is supported by Anadolu University Scientific Research Projects Committee (BAP-1001F37).

Analytic hierarchy process application in selecting the mode of transport for a logistics company

Scipedia content — Tue, 16 Feb 2021 11:15:29 +0100

SUMMARY As a multi-criteria decision-making (MCDM) method, the analytic hierarchy process (AHP) has been used considerably to solve hierarchical or network-based decision problems in socio-economic fields. Following an in-depth explanation of the transport function in logistics and an overview of the MCDM methods, the AHP model is employed in the paper for a logistics company in selecting the most suitable way of transportation between two given locations in Turkey. The criteria used in the selection of transportation modes are identified as the cost, speed, safety, accessibility, reliability, environmental friendliness, and flexibility. Several cost parameters (transportation, storage, handling, bosphorus crossover) are incorporated into the decision-making process. The application is carried out in instructional character. The results of the study indicate that the railway transportation, which is not widely used in Turkey, is also an alternative and suitable means of transportation. Copyright © 2013 John Wiley & Sons, Ltd.

Estimation of the Acid Dissociation Constant of Perfluoroalkyl Carboxylic Acids through an Experimental Investigation of their Water-to-Air Transport

Scipedia content — Tue, 16 Feb 2021 11:11:51 +0100

The acid dissociation constants (pKas) of perfluoroalkyl carboxylic acids (PFCAs) have been the subject of discussion in the literature; for example, values from -0.2 to 3.8 have been suggested for perfluorooctanoic acid (PFOA). The dissociated anionic conjugate bases of PFCAs have negligible air-water partition coefficients (KAWs) and do not volatilize from water. The neutral acids, however, have relatively high KAWs and volatilization from water has been demonstrated. The extent of volatilization of PFCAs in the environment will depend on the water pH and their pKa. Knowledge of the pKas of PFCAs is therefore vital for understanding their environmental transport and fate. We investigated the water-to-air transfer of PFCAs in a novel experimental setup. We used ∼1 μg L(-1) of PFCAs in water (above environmental background concentrations but below the concentration at which self-association occurs) at different water pH (pH 0.3 to pH 6.9) and sampled the PFCAs volatilized from water during a 2-day experiment. Our results suggest that the pKas of C4-11 PFCAs are "1.6. For PFOA, we derived a pKa of 0.5 from fitting the experimental measurements with a volatilization model. Perfluoroalkane sulfonic acids were not volatilized, suggesting that their pKas are below the investigated pH range (pKa "0.3).

The User Costs of Air Travel Delay Variability

Scipedia content — Tue, 16 Feb 2021 11:08:30 +0100

We derive the expected user costs of U.S. domestic air travel delay variability taking into account scheduling behavior of travelers. Travelers do not only consider mean arrival delays but also face scheduling costs because they arrive too early or too late at their destination. The model allows travelers to anticipate arrival delay variability by choosing an earlier flight. We show that the expected user costs of U.S. air traffic delays are almost doubled if expected schedule delay of travelers is accounted for, whereas the benefits of improvements in mean delay are underestimated by 16% if arrival delay variability is ignored.

EVs and post 2020 CO2 targets for passenger cars

Scipedia content — Tue, 16 Feb 2021 11:06:53 +0100

This paper analyses what post 2020 targets may be necessary for the European CO2 legislation for passenger cars in order to reach the overall sectoral goal of 60% reduction of transport's greenhouse gas emissions by 2050 relative to 1990, as defined in the European Commission's White Paper. The required target levels are found to depend strongly on the contribution that passenger cars need to make to reaching the overall target, on the assumed growth of passenger car mobility, and on the extent to which biofuels could be available for fuelling passenger cars. To what extent electric vehicles and other low emission vehicles such as plug-in hybrids and fuel cell electric vehicles are needed to meet the post-2020 targets depends on the target level and on the minimum CO2 emissions that can be reached in conventional vehicles. Almost all assessed scenarios, require significant amounts of low emission vehicles to be sold from 2030 or 2035 onwards. Electric and plug-in vehicles are in the early stage of market introduction now, but developments are fragile could end up in a 'valley of death'. Defining a sufficiently low passenger car CO2 target for 2025 may be an effective instrument to motivate manufacturers to continue their efforts in the marketing and further development of these vehicles. This is important for maintaining the momentum of the transition towards large-scale application of low CO2 emitting vehicles.

Document type: Article

Modeling the Polycentric Transition of Cities

Scipedia content — Tue, 16 Feb 2021 11:03:32 +0100

Empirical evidence suggest that most urban systems experience a transition from a monocentric to a polycentric organisation as they grow and expand. We propose here a stochastic, out-of-equilibrium model of the city which explains the appearance of subcenters as an effect of traffic congestion. We show that congestion triggers the unstability of the monocentric regime, and that the number of subcenters and the total commuting distance within a city scale sublinearly with its population, predictions which are in agreement with data gathered for around 9000 US cities between 1994 and 2010.

Comment: 11 pages, 12 figure

Traffic congestion detection in large-scale scenarios using vehicle-to-vehicle communications

Scipedia content — Tue, 16 Feb 2021 10:59:59 +0100

Cooperative vehicular systems are currently being investigated to design innovative ITS (Intelligent Transportation Systems) solutions for road traffic management and safety. Through the wireless exchange of information between vehicles, and between vehicles and infrastructure nodes, cooperative systems can support novel decentralized strategies for ubiquitous and more cost-attractive traffic monitoring. In this context, this paper presents and evaluates CoTEC (COperative Traffic congestion detECtion), a novel cooperative technique based on Vehicle-to-Vehicle (V2V) communications designed to detect road traffic congestion. CoTEC is evaluated under large-scale highway scenarios using iTETRIS, a unique open source simulation platform created to investigate the impact of cooperative vehicular systems. The obtained results demonstrate CoTEC’s capability to accurately detect and characterize road traffic congestion conditions under different traffic scenarios and V2V penetration rates. In particular, CoTEC results in congestion detection probabilities higher than 90%. These results are obtained without overloading the cooperative communications channel. In fact, CoTEC reduces the communications overhead needed to detect road traffic congestions compared to related techniques by 88%.

A feasibility study of fast charging infrastructure for EVs on highways

Scipedia content — Tue, 16 Feb 2021 10:57:37 +0100

A Prototype of Ship Routing Decision Support System for an Operational Oceanographic Service.

Scipedia content — Tue, 16 Feb 2021 10:51:12 +0100

prototype for an operational ship routing Decision Support System using time-dependent meteo-oceanographic fields is presented. The control variable is ship course, which is modified using a directional resolution of less than 27 degrees. The shortest path is recovered using a modified Dijkstra’s algorithm. Safety restrictions for avoiding surfriding and parametric rolling according to the guidelines of the International Maritime Organization (IMO) are implemented. Numerical experiments tailored on a medium-size vessel are presented and perspectives of development of the system are outlined.

The potential of alternative rail freight transport corridors between central europe and china

Scipedia content — Tue, 16 Feb 2021 10:48:16 +0100

The paper examines the potential of three rail corridors: Trans-Sib, Central and TRACECA for freight transport between Central Europe and China. The paper applies a qualitative research method including a review of current literature and interviews. The research examines the technical, operational and bureaucratic conditions of the corridors. The research finds that the unreliable transit time, higher cost and damage and theft of cargo are the most pressing barriers to towards offering an efficient and integrated logistics and supply chain service along the corridors. This is due to, amongst others, problematic, multiple border-crossings and the lack of visible cooperation among the countries. The technical and operational barriers include a change of gauge, differing power supply and signalling systems and non-automated and fragmented information systems. The research also finds that the Trans-Sib is the most attractive corridor currently running and shows promise with the active contribution from the Russian government and relevant direct stakeholders such as Russian Railway (RZD). The TRACECA route is the most problematic option due to, among others, numerous border-crossings, infrastructure and rolling stock constraints and other associated problems.

Leakage monitoring using percolation sensors for revealing structural damage in engineering structures

Scipedia content — Tue, 16 Feb 2021 10:47:05 +0100

SUMMARY There is a continuous need for the monitoring of engineering structures, especially when scheduled inspections are difficult to perform or if they are too expensive. The present paper gives some results on the performance of sensors on the basis of percolation thresholds that are able to detect leakage of diverse harmful liquids, such as water, hydraulic liquids, kerosene and jet engine oils. The focus here lies on sensor systems that give semi-quantitative, fuse-like information on the presence of harmful liquids, which indirectly gives evidence on the presence of structural damage. The common underlying principle is the interruption of percolation conductivity when the respective sensing material is exposed to harmful liquids; that is, the electrical conductivity is essentially lost by sorption and swelling of a dedicated matrix material. The temperature dependence and response times give valuable information on the usability of the sensor in the respective environments. The sensor can be manufactured as a cord sensor or as self-adhesive patches where the functional layer is deposited by screen printing. Copyright © 2013 John Wiley & Sons, Ltd.

The emergence and evolution of OpenStreetMap: a cellular automata approach

Scipedia content — Tue, 16 Feb 2021 10:46:34 +0100

Collaborative mapping projects, such as OpenStreetMap (OSM), have received tremendous amounts of contributed data from voluntary participants over time. So far, most research efforts deal with data quality issues, but the OSM evolution across space and over time has not been noted. Therefore, this study is dedicated to the evolution of the contributed information in order to understand an emergent phenomenon of so-called collaborative contributing. The main objective of this paper is to monitor the evolutional pattern of OSM and predict potential future states through a cellular automata (CA) model. This is exceedingly relevant for numerous OSM-based applications. Descriptive spatiotemporal analysis of the contributions for the time period 2007–2012, using the city of Heidelberg (Germany) as a case study, reveals that early contributions are given three years after the launching of OSM, while after nearly six years, most of the areas are discovered. The simulation results for the validated CA model, predicting OSM states for 2014, provide clear evidence that most of the areas have been explored three years after people began mapping until 2010, and thereafter, the densification process has begun and will cover most parts of the city although the amount of contribution depends on the land use types.

A New Traffic Congestion Prediction Model for Advanced Traveler Information and Management Systems

Scipedia content — Tue, 16 Feb 2021 10:44:18 +0100

The increase of wasted time and pollution due to vehicular traffic has paved the way to many different countermeasures, ranging from the enforcement of congestion tolls to the commercialization of vehicles powered by low-emission hybrid engines. Advanced traveler information systems (ATISs), which are capable of supplying updated traffic information to all those citizens that are driving through city roads, represent a prominent approach to combat vehicular congestion. In brief, ATISs are concerned with collecting, processing, and disseminating traffic information, providing data that can be profitably exploited by an on-board navigation system to compute the most convenient route to a given destination. Indeed, their role becomes progressively more relevant as their accuracy and reliability increases, thus encouraging more and more people to utilize them while driving. With this in mind, we devised a new congestion detection model that accurately estimates and forecasts the short-term congestion state of a road without requiring any prior knowledge regarding any of its parameters. Such model can be easily integrated within an ATIS and usefully applied to any given road. The efficacy of our model is here proved through the results of several experiments, which witness the validity of our approach. Copyright © 2012 John Wiley & Sons, Ltd.

Multi-scale analysis of the European airspace using network community detection

Scipedia content — Tue, 16 Feb 2021 10:42:48 +0100

We show that the European airspace can be represented as a multi-scale traffic network whose nodes are airports, sectors, or navigation points and links are defined and weighted according to the traffic of flights between the nodes. By using a unique database of the air traffic in the European airspace, we investigate the architecture of these networks with a special emphasis on their community structure. We propose that unsupervised network community detection algorithms can be used to monitor the current use of the airspaces and improve it by guiding the design of new ones. Specifically, we compare the performance of three community detection algorithms, also by using a null model which takes into account the spatial distance between nodes, and we discuss their ability to find communities that could be used to define new control units of the airspace.

Comment: 22 pages, 14 figure

Document type: Article

Coordinated Charging of Electric Vehicles for Congestion Prevention in the Distribution Grid

Scipedia content — Tue, 16 Feb 2021 10:39:26 +0100

Distributed energy resources (DERs), like electric vehicles (EVs), can offer valuable services to power systems, such as enabling renewable energy to the electricity producer and providing ancillary services to the system operator. However, these new DERs may challenge the distribution grid due to insufficient capacity in peak hours. This paper aims to coordinate the valuable services and operation constraints of three actors: the EV owner, the Fleet operator (FO) and the Distribution system operator (DSO), considering the individual EV owner’s driving requirement, the charging cost of EV and thermal limits of cables and transformers in a distribution grid capacity market framework. Firstly, a theoretical market framework is described. Within this framework, FOs who represent their customer’s (EV owners) interests will centrally guarantee the EV owners’ driving requirements and procure the energy for their vehicles with lower cost. The congestion problem will be solved by a coordination between DSO and FOs through a distribution grid capacity market scheme. Then, a mathematical formulation of the market scheme is presented. Further, some case studies are shown to illustrate the effectiveness of the proposed solutions.

Monocular Road Terrain Detection by Combining Visual and Spatial Information

Scipedia content — Tue, 16 Feb 2021 10:39:11 +0100

For future driver assistance systems and autonomous vehicles, the road course, i.e., the width and shape of the driving path, is an important source of information. In this paper, we introduce a new hierarchical two-stage approach for learning the spatial layout of road scenes. In the first stage, base classifiers analyze the local visual properties of patches extracted from monocular camera images and provide metric confidence maps. We use classifiers for road appearance, boundary appearance, and lane-marking appearance. The core of the proposed approach is the computation of SPatial RAY (SPRAY) features from each metric confidence map in the second stage. A boosting classifier selecting discriminative SPRAY features can be trained for different types of road terrain and allows capturing the local visual properties together with their spatial layout in the scene. In this paper, the extraction of road area and ego-lane on inner-city video streams is demonstrated. In particular, the detection of the ego-lane is a challenging semantic segmentation task showing the power of SPRAY features, because on a local appearance level, the ego-lane is not distinguishable from other lanes. We have evaluated our approach operating at 20 Hz on a graphics processing unit on a publicly available data set, demonstrating the performance on a variety of road types and weather conditions.

Effectiveness of smart charging of electric vehicles under power limitations

Scipedia content — Tue, 16 Feb 2021 10:34:55 +0100

SUMMARY This article investigates charging strategies for plug-in hybrid electric vehicles (PHEV) as part of the energy system. The objective was to increase the combined all-electric mileage (total distance driven using only the traction batteries in each PHEV) when the total charging power at each workplace is subject to severe limitations imposed by the energy system. In order to allocate this power optimally, different input variables, such as state-of-charge, battery size, travel distance, and parking time, were considered. The required vehicle mobility was generated using a novel agent-based model that describes the spatiotemporal movement of individual PHEVs. The results show that, in the case of Helsinki (Finland), smart control strategies could lead to an increase of over 5% in the all-electric mileage compared to a no-control strategy. With a high prediction error, or with a particularly small or large battery, the benefits of smart charging fade off. Smart PHEV charging strategies, when applied to the optimal allocation of limited charging power between the cars of a vehicle fleet, seem counterintuitively to provide only a modest increase in the all-electric mileage. A simple charging strategy based on allocating power to PHEVs equally could thus perform sufficiently well. This finding may be important for the future planning of smart grids as limiting the charging power of larger PHEV fleets will sometimes be necessary as a result of grid restrictions. Copyright © 2013 John Wiley & Sons, Ltd.

Sustainable transportation in Argentina: Values, beliefs, norms and car use reduction

Scipedia content — Tue, 16 Feb 2021 10:31:30 +0100

Most Latin American countries face important environmental and societal problems associated with an increase in car traffic, and only recently, transport policies aimed at reducing these harmful consequences of car use have begun to be discussed and put on the public agenda of these countries. Surprisingly, little is known about the factors influencing the acceptability of transport policies and intentions to reduce car use in Latin America, as studies on acceptability of transport policies have typically been conducted in Europe. Previous evidence from European samples - where reducing car used had been widely discussed - showed that the Value-Belief-Norm (VBN) theory of environmentalism was an adequate theoretical framework to predict the acceptability of a transport pricing policy, as well as the intention to reduce car use when this policy would be implemented. But can these results be generalised to non-European samples? In this paper, we report results of a questionnaire study among 160 participants from Buenos Aires, Argentina, aimed to test the VBN theory. We found that the VBN theory was indeed also successful in explaining policy acceptability and intention to reduce car use in Argentina. In addition, we found support for the causal structure of the variables in VBN theory. Interestingly, biospheric and hedonic values were also directly and significantly related to feelings of moral obligation when intermediate variables were controlled for. These results suggest that normative considerations, activated by values, indeed predict policy acceptability and the intention to reduce car use in Argentina and that these considerations should be taken into account to increase the acceptability of policies aimed at reducing car use. (C) 2013 Elsevier Ltd. All rights reserved.

Towards guidelines for transition of control

Scipedia content — Tue, 16 Feb 2021 10:30:38 +0100

There is a trend in Advanced Driver Assistance systems towards increased automation. Current systems and near-future systems will not yet be able to deal with all different situations that can be encountered and therefore need to share control of the vehicle with the driver. To safely and comfortably share control, a method for the transition of control (from manual to automated driving and vice versa) needs to be developed. This involves answering research questions like ‘how should the system take over’, ‘how can the driver take back control’, ‘can the driver be regarded as a backup if the system fails’, etc. This paper concentrates on finding different parameters and settings that may influence the transition of control for a ‘virtual tow bar’ system that is being developed at TNO . This serves as a first step to finding more general guidelines for transition of control and to develop necessary procedures, models and tools to evaluate these guidelines. Results of a first simulator experiment are presented and discussed.

Efficiency and Robustness in a Support Platform for Intelligent Airport Ground Handling

Scipedia content — Tue, 16 Feb 2021 10:29:19 +0100

One of the effects of the development of air traffic during recent years is the increase of congestion on major airports and their aprons, where ground handling operations take place. Efficiency and safety issues become important on the aprons. The “Integrated Airport Apron Safety Fleet Management – AAS” project aims at setting a decision support system for an efficient and safe management of apron traffic, taking advantage of information gathered by “intelligent” vehicles equipped with on-board positioning and monitoring systems. In this project, we optimize the assignment of vehicles to apron operations. We present a mathematical formulation of the problem and sketch a fast sequential heuristic, which provides efficient assignments based on real-time data on position and status of vehicles and operations. We then discuss how the procedure can reach good trade-offs between efficiency and robustness against unpredicted, but frequent, delays occurring in real-time at airports. The proposed approach has been applied to a major European airport (Berlin’s Tegel), leading to efficiency improvements and reduction of expected delays due to handling operations.

Airport apron capacity: estimation, representation, and flexibility

Scipedia content — Tue, 16 Feb 2021 10:23:10 +0100

SUMMARY This paper addresses some important issues related to airport apron capacity planning and management. An overview of existing apron models for supporting planning studies and for optimizing available resources utilization is given, with an emphasis on analytical models for apron capacity estimation. Constraints on apron usage, physical and operational with respect to different users, are discussed in detail, together with their impact on apron capacity. Simple extension of existing apron capacity estimation models is suggested accounting for constraints both on aircraft types and dominant users. Further on, instead of expressing apron capacity through a single number, an apron capacity envelope is used to illustrate capacity changes, that is, an apron's ability to accept various mixes of dominant users in demand. The apron capacity envelope provides information on capacity for one apron configuration (with respect to stand size and policy of usage) and a given fleet mix, for different shares of dominant users in demand. Finally, apron capacity flexibility is discussed with respect to its role in apron capacity planning and management. It is suggested how to express and interpret apron capacity flexibility. Copyright © 2013 John Wiley & Sons, Ltd.

A state-of-the-art review of techno-economic models predicting the costs of CO2 pipeline transport

Scipedia content — Tue, 16 Feb 2021 10:22:15 +0100

This study aims to provide a systematic overview and comparison of capital and O&M costs models for CO2 pipelines and booster stations currently available in literature. Our findings indicate significantly large cost ranges for the results provided by the different cost models. Two main types of capital cost models for pipeline transport were found in literature, models relating diameter to costs and models relating mass flow to costs. For the nine diameter based models examined, a capital cost range is found of, for instance, 0.8–5.5 M€2010/km for a pipeline diameter of 0.8 m and a length of 25 km. For the five mass flow based cost models evaluated in this study, a cost range is found of, for instance, 0.9–2.1 M€2010/km for a mass flow of 750 kg/s over 25 km (TRUNK-25). An important additional factor is that all capital costs models for CO2 pipeline transport, directly or indirectly, depend on the diameter. Therefore, a systematic overview is made of the various equations and parameter used to calculate the diameter. By applying these equations and parameters to a common mass flow, height difference and length result in diameters between 0.59 and 0.91 m for TRUNK-25. The main reason for this range was different assumptions about specific pressure drop and velocity. Combining the range for diameter, mass flow and diameter based cost models gives a capital and levelized cost range which varied by a factor 10 for a given mass flow and length. The levelized cost range will further increase if the discrepancy in O&M costs is added, for which estimations vary between 4.5 and 75 €/m/year for a pipeline diameter of 0.8 m. On top of this, most cost models underestimate the capital costs of CO2 pipelines. Only two cost models (namely the models who relate the costs to the weight of the pipeline) take into account the higher material requirements which are typically required for CO2 pipelines. The other sources use existing onshore natural gas pipelines as the basis for their cost estimations, and thereby underestimating the material costs for CO2 pipelines. Additionally, most cost models are based on relatively old pipelines constructed in the United States in the 1990s and early 2000s and do not consider the large increase in material prices in the last several years. Furthermore, key model characteristics are identified for a general cost comparison of CCS with other technologies and a system analysis over time. For a general cost comparison of CCS with other technologies, pipeline cost models with parameters which have physical or economic meaning are the preferred option. These are easy to interpret and can be adjusted to new conditions. A linear cost model is an example of such an model. For a system analysis over time, it is advised to adapt a pipeline cost model related to the weight of the pipeline, which is the only cost model that specifically models thickness of the pipeline and include material prices, to incorporate the effect of impurities and pipeline technology development. For modeling booster station costs, a relation between capacity and costs including some economies of scale seems to be the most appropriate. However, the cost range found in literature is very large, for instance, 3.1–3.6 M€2010 for a booster station with a capacity of 1.25 MWe. Therefore, validation of the booster station cost is required before such models are applied in further research.

Determinants of completed railway suicides by psychiatric in-patients: case-control study

Scipedia content — Tue, 16 Feb 2021 10:21:58 +0100

Background"/jats:title""jats:p"Suicide prediction during psychiatric in-patient treatment remains an unresolved challenge."/jats:p""/jats:sec""jats:sec""jats:title"Aims"/jats:title""jats:p"To identify determinants of railway suicides in individuals receiving in-patient psychiatric treatment."/jats:p""/jats:sec""jats:sec""jats:title"Method"/jats:title""jats:p"The study population was drawn from patients admitted to six psychiatric hospitals in Germany during a 10-year period (1997–2006). Data from 101 railway suicide cases were compared with a control group of 101 discharged patients matched for age, gender and diagnosis."/jats:p""/jats:sec""jats:sec""jats:title"Results"/jats:title""jats:p"Predictors of suicide were change of therapist (OR = 22.86, "jats:italic"P"/jats:italic" = 0.004), suicidal ideation (OR = 7.92, "jats:italic"P"/jats:italic"

Re-fueling road transport for better air quality in India

Scipedia content — Tue, 16 Feb 2021 10:17:13 +0100

Road transport in India plays a vital role in our growing economy. Given an aggressive vehicle sales outlook through 2030, in order to maintain a balance between the energy demand, growing on-road emissions, and overall air quality in the cities, there is a need to implement and enforce Bharat-5 standards (equivalent of Euro-V) nationwide by 2015. Any delay in its implementation or even staggered implementation of the standards will result in a delayed response for improving air quality in the Indian cities.

A Fast Heuristic for Airport Ground-Service Equipment–and–Staff Allocation

Scipedia content — Tue, 16 Feb 2021 10:14:48 +0100

With the recent increase of air traffic, major airports become more and more congested: sensible delays may be caused by ground operations, and problems related to the efficiency and the safety of the apron area assume more and more importance. In this paper, we consider the problem of determining an efficient allocation of ground service equipment and staff to aircraft standing on the apron, as emerged in the framework of the European sponsored project “Integrated Airport Apron Safety Fleet Management – AAS”. After providing a mathematical formulation for the problem, we suggest a fast sequential heuristic to be integrated in the real time dispatching decision support systems normally adopted in modern airports. The procedure has been applied in the AAS context, showing to be able to improve efficiency of handling operations.

Location choice for a continuous simulation of long periods under changing conditions

Scipedia content — Tue, 16 Feb 2021 10:14:13 +0100

Relatively little attention has been paid to the relationship between commute time variances and city size. In this paper, we utilize 2009 Nationwide Highway Travel Survey data and test the relationship between area commute-time means as well as variances in metropolitan-area size. We include tests for metropolitan areas as a whole and for residents from urban, suburban, second city, and town-and-county areas. The regression analysis shows that all estimated slopes are statistically significant but not much greater than zero. Commute time means and variances are highly correlated. These relationships are also invariant with respect to the place of residence. An extensive collection of literature provides evidence for the co-location of workers and jobs hypothesis: average commute times do not rise appreciably as metropolitan population increases. We conclude that these results are additional, although indirect, evidence for the co-location hypothesis.

Branch and Price for the Time-Dependent Vehicle Routing Problem with Time Windows

Scipedia content — Tue, 16 Feb 2021 10:11:07 +0100

This paper presents a branch-and-price algorithm for the time-dependent vehicle routing problem with time windows (TDVRPTW). We capture road congestion by considering time-dependent travel times, i.e., depending on the departure time to a customer, a different travel time is incurred. We consider the variant of the TDVRPTW where the objective is to minimize total route duration and denote this variant the duration minimizing TDVRPTW (DM-TDVRPTW). Because of time dependency, vehicles' dispatch times at the depot are crucial as road congestion might be avoided. Because of its complexity, all known solution methods to the DM-TDVRPTW are based on (meta-)heuristics. The decomposition of an arc-based formulation leads to a set-partitioning problem as the master problem, and a time-dependent shortest path problem with resource constraints as the pricing problem. The master problem is solved by means of column generation, and a tailored labeling algorithm is used to solve the pricing problem. We introduce new dominance criteria that allow more label dominance. For our numerical results, we modified Solomon's data sets by adding time dependency. Our algorithm is able to solve about 63% of the instances with 25 customers, 38% of the instances with 50 customers, and 15% of the instances with 100 customers.

Travelers' preferences in multimodal networks: Design and results of a comprehensive series of choice experiments

Scipedia content — Tue, 16 Feb 2021 10:09:45 +0100

The modeling of individuals' choice behavior in integrated multimodal transport networks requires the estimation of preference parameters related to the trade-off between uni-modal trips and multimodal combinations of private and public modes as well as relevant attributes of access, main and access stages of the trip. The stated choice method is a well-established method to estimate travel choice models empirically. However, including all relevant elements in a single experiment will not only result in choice tasks that are too complex for respondents but will also lead to choice-sets that include options that are not feasible for a given trip distance. To overcome this problem, this paper develops an approach that involves the use of a series of SP experiments to estimate a single comprehensive multimodal travel choice model. In total, four experiments are designed focusing on particular multimodal (including Park-and-Ride options) and public-transport choices for trips of varying distance. A representative national sample (N = 2746) of individuals from the Netherlands participated in the experiments through an online questionnaire. The data pooled across experiments are used to estimate the model in a scaled error-component-mixed multinomial logit framework. In this way, valuations of time, costs and service-quality attributes could be estimated on a relatively high level of detail concerning modes and trip stages. Comparisons with previous research indicate that the parameter estimates have reasonable values. The estimation results offer rich information on how travelers tradeoff between travel-time, travel-costs and service-quality attributes in travel choice in multimodal networks. (C) 2013 Elsevier Ltd. All rights reserved.

Wide-angle vision for road views

Scipedia content — Tue, 16 Feb 2021 10:05:28 +0100

The field-of-view of a wide-angle image is greater than (say) 90 degrees, and so contains more information than available in a standard image. A wide field-of-view is more advantageous than standard input for understanding the geometry of 3D scenes, and for estimating the poses of panoramic sensors within such scenes. Thus, wide-angle imaging sensors and methodologies are commonly used in various road-safety, street surveillance, street virtual touring, or street 3D modelling applications. The paper reviews related wide-angle vision technologies by focusing on mathematical issues rather than on hardware.

Label switching over IEEE802.15.4e networks

Scipedia content — Tue, 16 Feb 2021 10:01:51 +0100

n open issue still to be addressed in low-power lossy networks (LLNs) is how the application requirements, the available transport services, the network layer routes, and the data link-layer resources are mapped efficiently. This can be explained by the fact that, in most LLNs, link-layer resources cannot be easily managed; this results in a best effort IP layer, and traffic engineering performed solely through flow control at the transport layer. The new IEEE802.15.4e standard defines a link-layer mechanism by which motes in the network synchronise and communicate by following a schedule. Each slot in that schedule can be seen as an atomic link-layer resource, which can be allocated to any arbitrary link in the network. The schedule can be built to match the bandwidth, latency and power requirements of each mote in the network. Managing that schedule is performed centrally in IEEE802.15.4e networks today. This paper explores a solution to achieve the same goal in a distributed manner. Specifically, we argue that this problem is very similar to traffic engineering on today's Internet. We show how multiprotocol label switching can be mapped to LLNs to manage the network's schedule. By using the completely fair distributed scheduler, we show by simulation how this novel link-layer resource allocation scheme yields a proper distribution of end-to-end delays among the motes and an average throughput that achieves the 70% of the maximum possible throughput in the worst conditions tested. Copyright © 2013 John Wiley & Sons, Ltd.

Application of Magnetocaloric Heat Pumps in Mobile Air-Conditioning

Scipedia content — Tue, 16 Feb 2021 09:59:26 +0100

[EN] Air-conditioning (AC) is an important sub-system in electric vehicles (EVs). AC is responsible for the highest energy consumption among all the auxiliary systems. As the energy is delivered by the batteries, the power consumption for airconditioning can imply a significant reduction of the vehicle autonomy. Given the actual state of the art and the temperature and power requirements, electrically driven compressors are the most feasible solution. However, vapour-compression systems are reaching their maximum efficiency. Using innovative technologies can improve the performance of standard systems and hereby increase the vehicle autonomy. This paper presents the first steps in the design of a magnetocaloric air-conditioner for an electric minibus. The system will include two reversible magnetocaloric heat pumps, one in the front part of a minibus and one on the rear. The heat rejection system of the power electronics will be coupled to the air-conditioning system. In order to assist the design of the system, a dynamic model has been developed for the cabin, the hydraulic loops and heat exchangers, and the magnetocaloric units. An integrated design of the complete system is necessary, as it will work under dynamic conditions which depend on the thermal load in the cabin. In this paper, the operation conditions of the magnetocaloric units are presented and the design of the magnetocaloric air-conditioner is discussed. This work has been developed under the frame of the European Project ICE which aims to develop an innovative mobile air-conditioning system for EVs based on a magnetocaloric heat pump. This work has been supported by the European Commission under the 7th European Community framework program as part of the ICE project “MagnetoCaloric Refrigeration for Efficient Electric Air-Conditioning”, Grant Agreement no. 265434. B. Torregrosa-Jaime acknowledges the Spanish Science and Innovation Ministry (Ministerio de Ciencia e Innovación) for receiving the Research Fellowship FPU ref. AP2010-2160. Torregrosa-Jaime, B.; Vasile-Müller, C.; Risser, M.; Muller, C.; Corberán, JM.; Payá Herrero, J. (2013). Application of Magnetocaloric Heat Pumps in Mobile Air-Conditioning. SAE International Journal of Passenger Cars. Mechanical Systems. 6(2):520-528. https://doi.org/10.4271/2013-01-0239 S 520 528 6 2

Can slow steaming lower cost impacts of sulphur directive - shippers perspective

Scipedia content — Tue, 16 Feb 2021 09:59:01 +0100

The International Maritime Organization (IMO) (2013, 2014) and the European Parliament (EP) (2005, 2012) have addressed the matter that harmful air emissions should be decreased in shipping transportation. The purpose of this empirical case study is to examine and anticipate in detail if slow steaming in freight shipping can bring any economically positive effects to shippers in the new fuel situation of 2015, where the sulphur directive is to be followed. As research data for our analysis, we used information on the cost management and transportation of a paper mill. The data was used to study how slow steaming would impact the gross margins of a large paper mill in different markets in 2015. The results of this study can be summarised as the notion that the negative economic impacts of the sulphur directive can be lowered to some extent by using slow steaming on short sea shipping routes. The positive impacts gained from slow steaming will vary largely from market to market. We determined that a case study is a relevant method to study and to reveal economic consequences produced by environmental directives as well as how much slow steaming can remove presupposed negative impacts.

A ride comfort tyre model for off-highway vehicles

Scipedia content — Tue, 16 Feb 2021 09:58:36 +0100

Tyre modelling is a major challenge when using time domain multibody simulation models to evaluate ride comfort on off-highway commercial vehicles. Further, parameters for these big tyres are difficult to obtain and thus, commercial car tyre models are difficult to apply. In this research work, a simple vertical tyre model for off-highway ride comfort evaluation is suggested. A displaced volume approach has been developed and combined with the slip theory to yield a tyre model that can be characterised by only three parameters. Full scale measurements on a dump truck have been carried out. Force responses from measurements are compared to the simulation results. Acceleration responses and the level of whole-body vibrations have also been compared.

Distributive effects of new highway infrastructure in the Netherlands : The role of network effects and spatial spillovers

Scipedia content — Tue, 16 Feb 2021 09:52:51 +0100

Network effects and spatial spillovers are intrinsic impacts of transport infrastructure. Network effects imply that an improvement in a particular link in a network generates effects in many other elements of that network, while spillover effects can be defined as those impacts occurring beyond the regions where the actual transport investment is made. These two related effects entail a redistribution of impacts among regions, and their omission from road planning is argued to cause the systematic underestimation of the profitability of transport projects and therefore the public financing they require. However, traditional transport appraisal methodologies fail to consider network and spillover effects. In this study we focus on the spillover impacts of two highway sections planned in the city region of Eindhoven, located in the Dutch province of Noord-Brabant, a region with traffic congestion problems. The new road infrastructure will be financed mainly by national government, the province and the urban region of Eindhoven (‘Stadsregio Eindhoven’), which consists of 21 municipalities. We measure the benefits of the additional links in terms of travel time savings and the accompanying monetary gains. The results show that important spillovers occur in those municipalities close to the new links. The province of Noord-Brabant will benefit the most. We also found important spillovers in the province of Limburg. This latter province will benefit from reduced travel times without contributing financially to the establishment of the analysed new road links.

JRC.J.1-Economics of Climate Change, Energy and Transpor

Developing self-adaptive automotive systems

Scipedia content — Mon, 15 Feb 2021 12:28:28 +0100

Future Driving Assistance Systems (DAS) will have to react to changes within the system at runtime. This might be the case in Car-to-X systems where the availability of communication partners changes dynamically. Another example are systems like DAS for truck and trailer combinations where a trailer might be disconnected and replaced by another one several times a day. State-of-the-art DAS are not capable of handling these runtime changes. In our approach we make usage of the principles of Service-orientation to generate self-adaptive DAS on architectural level. But this technical approach requires the definition of a development process that fits into the practices within the automotive industry. This paper introduces SOMA4DDAS, a model-based development process based on the UML profile SoaML. SOMA4DDAS describes a tri-phase procedure to transfer an idea for a DAS into a detailed specification of the application and the Services involved. These phases are integrated into the "core process for system and software development" (CPSSD), a standard process within the automotive industry. The paper illustrates the benefits of this approach by developing a truck and trailer DAS consisting of 13 different Services.

Document type: Article

Investigating an all-hydraulic hybrid system for diesel-hydraulic rail cars

Scipedia content — Mon, 15 Feb 2021 10:38:35 +0100

Purpose This paper outlines a complex simulation model for parallel-hybrid diesel railcars with hydrodynamic power transmission. It contributes to the discussion concerning whether a hydrostatic recuperation system can be an alternative to electric systems using double-layer capacitors or flywheels. The paper focusses on a hybrid system with realistic parameters concerning mass, power, and energy content that should be applicable to both existing and newly built vehicles.

Document type: Article

Estimating MFDs in Simple Networks with Route Choice.

Scipedia content — Mon, 15 Feb 2021 10:36:05 +0100

The concept of the Macroscopic Fundamental Diagram (MFD) is elegant and attractive because it provides a global view of traffic behavior and performance at a network level. However, recent research shows that the MFD shape can be influenced by local traffic heterogeneities. Notably, route choices and heterogeneous local capacities may drive uneven (in space) or inconsistent (in time) distributions of congestion and then affect the shape and the scatter of the MFD. We are far from having a global understanding of the connections between local phenomena and the resulting MFD. This paper first aims to improve existing MFD estimation method for a succession of links with traffic signals. The new method overcomes previous limitations, notably regarding to the topology and signal settings regularities, by fully utilizing the receipts of the variational theory. Then, a single network with several parallel routes is investigated. MFDs on different routes are estimated with the variational method and then aggregated in a unified MFD for stationary and dynamic conditions and different sorts of equilibria (user and system optimum). It appears that the flow distribution among routes smoothly varies with respect to the total flow either in free-flow or congestion situations. Such a distribution is much more rough for system optimum, where it presents some discontinuities and is far from equity. This means that a control strategy able to lead such a network to the perfect system optimum would be hard to tune, especially in the congested regime. However, being able to determine the MFD corresponding to the system optimum provides a valuable reference to estimate the current efficiency of the considered network. Case studies for different simple networks and insights for generalization at the city level are proposed. (C) 2013 Elsevier Ltd. All rights reserved.

Document type: Article