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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
191

Re-scheduling the Railway Traffic using Parallel Simulated Annealing and Tabu Search : A comparative study

Gerdovci, Petrit, Boman, Sebastian January 2015 (has links)
Context: This study has been conducted in the area of train rescheduling. One of the most common types of disturbance scenarios are trains which have deviated from their originally planned arrival or departure times. This type of disturbance is of today handled manually by the train dispatcher, which in some cases can be cumbersome and overwhelmingly complex to solve. Therefore, there is an essential need for a train re-scheduling decision support system. Objectives: The aim of the study is to determine if parallel adaptations of simulated annealing(SA), and tabu search(TS) are able to find high quality solutions for the train re-scheduling problem. The study also aims to compare the two proposed meta-heuristics in order to determine the more adequate algorithm for the given problem. Methods: To answer the research question sequential and parallel versions of the algorithms were implemented. Further the research methodology of choice was experiment, were the meta-heuristics are evaluated based on 10 disturbance scenarios. Results: Parallel simulated annealing(PSA) is overall the better performing algorithm, as it is able to reduce the total delay by 585 seconds more than parallel tabu search(PTS) for the 10 disturbance scenarios. However, PTS is able to solve more conflicts per millisecond than PTS, when compared to their sequential versions. Conclusions: We conclude that both the parallel versions perform better than their sequential versions. Further, PSA is clearly able to outperform PTS in terms of minimizing the accumulated delay. One observation is that the parallel versions are not reaching their max efficiency per thread, this is assumed to be caused by the RAM. For future work we propose further investigation of why we are not reaching the max efficiency per thread, and further improvement of algorithm settings.
192

Algorithm for inserting a single train in an existing timetable

Ljunggren, Fredrik, Persson, Kristian January 2017 (has links)
The purpose with this report is to develop a network based insertion algorithm and evaluate it on a real-case timetable. The aim of the algorithm is to minimize the effect that that train implementation cause on the other, already scheduled traffic. We meet this purpose by choosing an objective function that maximizes the minimum distance to a conflicting train path. This ensures that the inserted train receives the best possible bottleneck robustness. We construct a graph problem, which solve with a modified version of Dijkstra’s algorithm. The complexity of the algorithm is Ο(s^2 t log⁡(s^2 t). We applied the algorithm on a Swedish timetable, containing 76 stations. The algorithm performs well and manage to obtain the optimal solution for a range of scenarios, which we have evaluated in various experiments. Increased congestion seemed to reduce the problem size. The case also show that a solution’s robustness decreases with increasing total number of departures. One disadvantage with the algorithm is that it cannot detect the best solution among those using the same bottleneck. We propose a solution to this that we hope can be implemented in further studies.
193

Transforming public space : re-generating Rissik station

Le Roux, J.C. (Johannes Calvyn) 24 November 2008 (has links)
The proposed project aims to transform the selected site and buildings at Rissik Station to new uses, along with the restoration and reuse of historical buildings. This amounts to a recycling and improved use of existing resources. / Dissertation (MArch(Prof))--University of Pretoria, 2009. / Architecture / unrestricted
194

Vysokorychlostní železniční přeprava ve Španělsku / High-Speed Railways in Spain

Přibylová, Veronika January 2008 (has links)
This thesis describes high-speed railway system in Spain. At the first part it concerns on the history of high-speed rails in the world, its legislation and the contribution of EU. The second part concentrates on the evolution in Spain, high speed infrastructure and trains. Mainly it analyzes the price policy.
195

Vlaková doprava v integrovaných dopravních systémech / Role of trains in integrated transport systems

Vrbík, Ivo January 2010 (has links)
The objective of this work is focused on trains and their role in integrated transport systems. The functionality of public train transport is shown on 2 most developped integrated systems in Czech republic. My work include comparison of these 2 systems and the role of trains in both of them.
196

Eco-routing and scheduling of Connected and Autonomous Vehicles

Houshmand, Arian 19 May 2020 (has links)
Connected and Autonomous Vehicles (CAVs) benefit from both connectivity between vehicles and city infrastructures and automation of vehicles. In this respect, CAVs can improve safety and reduce traffic congestion and environmental impacts of daily commutes through making collaborative decisions. This dissertation studies how to reduce the energy consumption of vehicles and traffic congestion by making high-level routing decisions of CAVs. The first half of this dissertation considers the problem of eco-routing (finding the energy-optimal route) for Plug-In Hybrid Electric Vehicles (PHEVs) to minimize the overall energy consumption cost. Several algorithms are proposed that can simultaneously calculate an energy-optimal route (eco-route) for a PHEV and an optimal power-train control strategy over this route. The results show significant energy savings for PHEVs with a near real-time execution time for the algorithms. The second half of this dissertation tackles the problem of routing for fleets of CAVs in the presence of mixed traffic (coexistence of regular vehicles and CAVs). In this setting, all CAVs belong to the same fleet and can be routed using a centralized controller. The routing objective is to minimize a given overall fleet traveling cost (travel time or energy consumption). It is assumed that regular vehicles (non-CAVs) choose their routing decisions selfishly to minimize their traveling time. A framework is proposed that deals with the routing interaction between CAVs and regular uncontrolled vehicles under different penetration rates (fractions) of CAVs. The results suggest collaborative routing decisions of CAVs improve not only the cost of CAVs but also that of the non-CAVs. This framework is further extended to consider congestion-aware route-planning policies for Autonomous Mobility-on-Demand (AMoD) systems, whereby a fleet of autonomous vehicles provides on-demand mobility under mixed traffic conditions. A network flow model is devised to optimize the AMoD routing and rebalancing strategies in a congestion-aware fashion by accounting for the endogenous impact of AMoD flows on travel time. The results suggest that for high levels of demand, pure AMoD travel can be detrimental due to the additional traffic stemming from its rebalancing flows, while the combination of AMoD with walking or micromobility options can significantly improve the overall system performance.
197

[en] DECISION SUPPORT SYSTEM FOR THE OPERATIONAL CONTROL CENTER IN THE RAILROAD TRAFFIC MANAGEMENT / [pt] SISTEMA DE APOIO À DECISÃO AO CENTRO DE CONTROLE OPERACIONAL NO GERENCIAMENTO DO TRÁFEGO FERROVIÁRIO

LUCIANA SILVEIRA NETTO NUNES 26 May 2004 (has links)
[pt] Esta pesquisa tem por objetivo conceber um sistema de apoio à decisão ao centro de controle operacional no gerenciamento do tráfego ferroviário. O sistema consiste na resolução de conflitos entre trens. Esta pesquisa justifica- se devido à deficiência encontrada pelos controladores de tráfego na tomada de decisões. Atualmente, as prioridades dos trens são pré-estabelecidas e, a partir da análise de um gráfico feito à medida que os eventos ocorrem, o planejamento do despacho de trens é realizado. As prioridades podem ser modificadas ao longo do dia, a partir de alguma ordem superior. Assim, existe a necessidade do desenvolvimento de um novo sistema que auxilie os controladores de tráfego na determinação da melhor solução para os conflitos entre trens. Inicialmente, foram realizados os levantamentos bibliográficos e de dados. Na revisão bibliográfica, foram analisados o sequenciamento de trens, condições de ultrapassagem e de cruzamentos e modelos de programação de trens. Em seguida, foi aplicada uma heurística proposta por Leal (2003) desenvolvida a partir da formulação de Szpigel (1972) e implementada em um programa de computador, na linguagem delphi. Esta heurística apresenta uma solução para os conflitos entre trens. A aplicação foi baseada nos dados fornecidos pela empresa MRS logística, situada em Juiz de Fora (MG). A partir da solução gerada por Leal (2003), foi desenvolvido um gráfico no Excel, utilizando a linguagem visual basic, onde são analisadas as programações dos trens com a solução dos conflitos. O objetivo final desta pesquisa é sugerir uma ferramenta de auxílio para o gerenciamento do tráfego ferroviário, contribuindo para a evolução e eficiência das ferrovias no Brasil. / [en] The objective of this research is to conceive a decision support system for the operational control center in the railroad traffic management. The system consists of the resolution of conflict between trains. The justification of this research is due to the deficiency founded by controllers of traffic in the decisions making. Currently, the trains priorities are previously established and, through the analysis of a done graph to the measure that the events go happening, these priorities can be modified. Thus, there is the necessity of the development of a new system which helps the controllers in the determination of the best alternative. Initially, the bibliographical surveys and the data-collectings had been made. In the bibliographic revision, the sequenciament of trains, ultraticket and crossing conditions, and trains programming models had been analyzed. The next step was the application of an heuristic developed by Leal (2003), based in the formularization of Szpigel (1972), and implemented in a computer program, in the Delphi language, showing the solution of conflicts between trains. The application was based in the data of MRS logistic company, situated in Juiz De Fora (MG). From the solution generated for Leal (2003), a graph in the excel was developed, using visual basic language, and shows the programmings of the trains with conflits solution. The final objective is to suggest a tool for helping the railroad traffic management, contributing for the evolution and efficiency of the railroads in Brazil.
198

[pt] ESTRATÉGIAS E TÁTICAS NOS TRENS DA SUPERVIA / [en] STRATEGIES AND TATICS AT SUPERVIA S RAIL

05 October 2012 (has links)
[pt] O presente trabalho discute o uso dos trens no Rio de Janeiro e, com o recurso da etnografia, enfoca alguns fenômenos que caracterizam a relação do usuário com o sistema de transporte ferroviário. Este, como todo espaço público, possui um conjunto de regras implícitas e explícitas que permeiam sua relação com o usuário. A partir das teorias de Michel Foucault e Michel de Certeau, são discutidas as tensões entre as normas disciplinadoras da empresa Supervia (a concessionária deste serviço) e as táticas empreendidas pelos usuários para enfrentá-las. / [en] The following work discuss about the use of the train commuters in Rio de Janeiro, and by ethnografy resources focuses some phenomenons wich caracterise the relationship of the users to this transport. As every public space, it has oficial and unoficial rules wich permeal the relationship with the users. From Michel Foucaut and Michel de Certeau theories, are discussed the stratch between the disciplinary rules of Supervia Company (concessionary of that service) and the tactics used by the users to go aganist it.
199

Nonlinear Seismic Responses of High-Speed Railway System considering Train-Bridge Interaction / 列車-橋梁連成系を考慮した高速鉄道システムの地震時非線形応答解析

Lu, Xuzhao 23 March 2020 (has links)
京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第22418号 / 工博第4679号 / 新制||工||1730(附属図書館) / 京都大学大学院工学研究科社会基盤工学専攻 / (主査)教授 KIM Chul-Woo, 教授 清野 純史, 教授 杉浦 邦征 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM
200

Computer-based decision support for handling uncertainty in railway traffic and transportation / Datorbaserat beslutstöd för hantering av osäkerhet i järnvägstrafik- och transporter

Törnquist, Johanna January 2004 (has links)
Railway transportation has great potential, but interdependencies in the railway traffic make trains very sensitive to disturbances, which can bedifficult to handle. Using railway in an intermodal transport chain may complicate the interconnections with other modes if there is large uncertainty in the performance of the railway. A study based on interviews with several customers of the Swedish National Railway Administration shows that the customers lack information regarding occurrences of disturbances and the consequences for their trains, i.e. the new estimated time of arrival. This information is necessary when taking actions within the customers’ organisation to minimise the negative impacts. Predicting the consequences of a disturbance and the effects of counter measures taken by the Swedish train traffic managers is today an overwhelming task considering there is no computational decision support available. However, provided that the traffic and decision-making could be simulated, the effects from disturbances and actions taken could be computed. Requirements regarding computational time for a simulation are obviously significant and affect the usefulness in a real-time environment. For strategic purposes, a simulator could also serve as an analytical tool for evaluating strategies for handling certain types of disturbances. An approach to model the different layers of such a simulator, taken into account the infrastructure, the traffic flow and the influence of the traffic management decisions and transport operators, is presented. The part that covers the interaction between train traffic and infrastructure has been implemented as a small-scale discrete-event simulator. The simulator is extended by an optimisation approach, attempting to act as decision support for the train traffic managers when handling disturbances by generating effective counter measures. It is composed by a linear model specifying the timetable of a sub-network and solved by optimisation software. Iteratively, a heuristic is applied to modify the timetable by changing meets and overtakes and generate a new updated linear model to be solved. In addition to consider the train traffic system as an explicit part of a transport chain, it can be seen as a black box where some relations between input and output are known. We have investigated how uncertainty in the reliability related to one or several transport links can be handled when combining several links into a transport chain. A simulation-based approach is proposed.

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