• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 7
  • 2
  • 1
  • 1
  • 1
  • Tagged with
  • 12
  • 12
  • 3
  • 3
  • 3
  • 3
  • 3
  • 3
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 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.
1

Introducing a New Quantitative Measure of Railway Timetable Robustness Based on Critical Points

Andersson, Emma, Peterson, Anders, Törnquist Krasemann, Johanna January 2013 (has links)
The growing demand for railway capacity has led to high capacity consumption at times and a delay-sensitive network with insufficient robustness. The fundamental challenge is therefore to decide how to increase the robustness. To do so there is a need for accurate measures that return whether the timetable is robust or not and indicate where improvements should be made. Previously presented measures are useful when comparing different timetable candidates with respect to robustness, but less useful to decide where and how robustness should be inserted. In this paper, we focus on points where trains enter a line, or where trains are being overtaken, since we have observed that these points are critical for the robustness. The concept of critical points can be used in the practical timetabling process to identify weaknesses in a timetable and to provide suggestions for improvements. In order to quantitatively assess how crucial a critical point may be, we have defined the measure RCP (Robustness in Critical Points). A high RCP value is preferred, and it reflects a situation at which train dispatchers will have higher prospects of handling a conflict effectively. The number of critical points, the location pattern and the RCP values constitute an absolute value for the robustness of a certain train slot, as well as of a complete timetable. The concept of critical points and RCP can be seen as a contribution to the already defined robustness measures which combined can be used as guidelines for timetable constructors.
2

Konvolucije eksternih faktora u oceni rizika vanrednih događaja na železnici / Convolution of external factors in the assessment of risk of accidents in railway system

Aleksić Dejan 08 December 2016 (has links)
<p>Istraživanje faktora koji utiču na nastanak vanrednih događaja na železnici se uobičajeno zasnivaju na analizi internih faktora, dominantno ljudskih faktora.<br />Eksterni faktori koji mogu imati značajan uticaj na povećanje rizika od nastanka vanrednog događaja u dosada&scaron;njoj praksi nisu ustanovljeni i kvantifikovani sa stanovi&scaron;ta uticaja na realizatore transpornog procesa.<br />Regularno ustanovljavanje eksternih faktora i njihova metrika zbog toga predstavlja osnovni protokol za procenu rizika od nastanka i prevenciju vanrednih događaja.</p> / <p>The study of factors that influence the occurrence of railway accidents are usually based on an analysis of internal factors, the dominant human factors.<br />External factors that can have a significant impact on increasing the risk of railway accidents in current practice are not established and quantified from the point of impact on the implementers exchange transport processes.<br />Regular establishment of external factors and their metrics is therefore a basic protocol for assessing the risk of railway accidents and prevention of extraordinary events.</p>
3

Vliv železničního hluku na cenu bydlení v Praze: studie hedonické ceny / The effect of the train noise on prices od properties in Prague:hedonic pricing method

Šebková, Veronika January 2010 (has links)
The aim of this diploma thesis is to determine what is the effect of the train noise on prices of properties in Prague. This influence is investigated by using the method of hedonic price. The theoretical part is devoted not only to the problematic of the train noise and its physical properties but also to its impact on humans and the prices of apartments. Then the train noise is specified as well as its issuers and the ways in which it is possible to defend from the negative effects of the impact of the train noise. The thesis also explains the various stages of the method of hedonic price together with the theoretical part of Foreign Studies which have been engaged in using the method of hedonic price and the train noise. In the empirical part are used the knowledge from search, the selected variables are discussed and are submitted to descriptive analysis and the hypothesis are given. Then the model works through a regression analysis of function of the method of hedonic price and the various results are discussed. This thesis finishes by calculating the implicit prices and elasticities for the individual variables in the selected models. At the very end recommendations and the benefits resulting from the analysis are drawn.
4

Optimering av takttidtabell för järnvägstrafik på en regional nivå : En fallstudie av fyra Mälarstäder / Optimisation of cyclic timetable for railway traffic on a regional level : A case study of "fyra Mälarstäder"

Dahlin, Niklas January 2018 (has links)
Effective commuting is an important part of regional development and attractiveness, where railway traffic is a favourable mode of transportation owing to it being energy efficient and environmentally friendly. Attaining more people to choose the train to commute is therefore desirable. A concept aiming to increase the use of railway traffic is cyclic timetable. At present the concept is most frequently used on a national level but there are possibilities to implement the ideas on a more regional level. The purpose of this thesis is to study if and how a cyclic timetable for railway traffic can be constructed and optimised for a region, more specifically the region “Fyra Mälarstäder”. Challenges and opportunities to implement this type of timetable on a regional level are also discussed. In order to construct a timetable for railway traffic several infrastructural limitations must be taken into account. An example that extensively limits railway capacity is single tracks. Hence, to be able to construct and optimise the timetable these limitations were formulated, together with a number of other criteria, mathematically as constraints for an optimisation problem. For the optimisation setup the objective function consisted of a sum of weighted trip times within the system, which in turn was minimised. Results conclude that a cyclic timetable could successfully be used for “Fyra Mälarstäder”. However, some aspects remain to be investigated, including train line continuation beyond the system boundaries of the study. As for the optimisation, it appears that the weighting of the objective function plays a considerable role to obtain a satisfying timetable. Varying and adjusting certain parameters may also be favourable to achieve a timetable as beneficial as possible. / Allt fler arbetspendlar i Sverige och Trafikverkets prognoser visar att ökningen kommer att fortsätta. För att pendlingen ska vara hållbar behöver allt fler resor göras kollektivt, och tåget som transportmedel är på många sätt ett bra alternativ. Tåget är snabbt och effektivt, samtidigt som det är ett mer miljövänligt trafikslag. Att få ännu fler att välja tåget, framför exempelvis bil, är därför önskvärt. Pendling sker idag både över kommun- och länsgränser, vilket innebär att regionala samarbeten kan underlätta för att åstadkomma så goda pendlingsmöjligheter som möjligt. Ett exempel på en sådant samarbete är Fyra Mälarstäder i samverkan (Eskilstuna, Västerås, Enköping, Strängnäs), vars förhoppning är att kunna utveckla regionen bland annat genom att förbättra kollektivtrafiken mellan städerna. Ett sätt att förbättra pendlingsmöjligheterna är att försöka åstadkomma en så gynnsam tidtabell som möjligt. Takttidtabell är ett intressant koncept, utvecklat för tågtrafiken i Schweiz, vilket kortfattat innebär att tåg avgår samma minut varje timme, och med jämna intervall. Konceptet innebär ofta också att låta tåg mötas vid knutpunkter i järnvägsnätet för att underlätta för byten till andra tåglinjer för fortsatt resa, vilket därmed knyter ihop tågtrafiken i ett större system. Syftet med denna studie är att undersöka om och hur en takttidtabell kan konstrueras och optimeras för en region som Fyra Mälarstäder. Optimeringen spelar en central roll för att få till en tidtabell som är så bra som möjligt. Därtill diskuteras även vilka utmaningar, men också vilka möjligheter det finns med att applicera takttidskonceptet på en regional nivå, eftersom det idag allt som oftast tillämpas nationellt. För att konstruera en tidtabell för järnvägstrafik måste flera begränsningar på järnvägen tas i hänsyn. Ett exempel som i hög grad begränsar kapaciteten är enkelspår, vilket följaktligen gör att tåg inte kan mötas på vissa sträckor. För att kunna konstruera takttidtabellen genom optimering formulerades dessa begränsningar, tillsammans med en rad andra kriterier, matematiskt som bivillkor till ett optimeringsproblem. För optimeringsuppställningen bestod målfunktionen av summan av viktade restider inom systemet, vilken i sin tur minimerades. Optimeringsproblemet implementerades i MATLAB som användes för att lösa problemet. Resultaten visar att takttidtabell med de kriterier som ställts upp i studien kan konstrueras, och möjligheter finns för att implementera denna för järnvägstrafiken mellan fyra Mälarstäder. Vissa aspekter återstår dock att utreda, däribland tåglinjers fortsatta sträckning utanför studiens systemgränser. Vad gäller optimeringsuppställningen framgår det att en viktning av målfunktionen spelar en ansenlig roll. Att variera och justera parametrar kan också vara en god idé för att få till en så tillfredsställande tidtabell som möjligt.
5

Železniční doprava po vstupu do EU. / Railway service after the entrance to the EU.

JANOUŠKOVÁ, Alena January 2008 (has links)
The aim of this thesis is to analyze the management, the marketing of products and conducting of the marketing questionnaire, by the help of it I want to evaluate the situation of this company. The partial aim is to find out a history, present progression, the behaviour of customers and workers and the service of railway traffic. At the end I want to propose my innovation.
6

Modélisation et optimisation d’un plan de transport ferroviaire en zone dense du point de vue des voyageurs / Passenger-oriented modelling and optimization of the railway transportation plan in a mass transit system

Brethomé, Lucile Isabelle 20 November 2018 (has links)
La conception d’un plan de transport d’un service ferroviaire est un processus qui se réalise entre deux ans et six mois avant la mise en service de celui-ci. Les principales phases de la conception sont la définition des dessertes, le calcul de la grille horaire et enfin l’organisation des roulements de rames et des conducteurs. La manière dont le plan de transport est conçu peut avoir de nombreuses conséquences sur la qualité de service : fréquence en gare insuffisante qui peut entrainer une perte de clients, robustesse de la grille horaire face à de petits incidents... En zone dense, tous ces éléments sont à prendre en compte, dès la conception de la grille horaire.Aujourd’hui, SNCF Transilien conçoit ses plans de transport en prenant d’abord en compte l’optimisation des ressources de production (sillons, rames et agents de conduite). Toutefois, l’augmentation des ressources mises en œuvre n’améliore plus l’adéquation du plan de transport à la demande des voyageurs. Ce mode de conception ne permet donc plus de faire face à l’augmentation de la demande de mobilité. C’est pourquoi il faut repenser la conception du plan de transport en intégrant immédiatement la dimension voyageuse.Nos travaux se concentrent sur les problématiques de conception de dessertes et de grille horaire, en prenant en compte le point de vue des voyageurs. Nous présentons un modèle multiobjectif de conception de dessertes, puis nous présentons un modèle de conception de grille horaire intégrant le choix d’itinéraire des voyageurs. Ensuite, nous présentons une méthode cherchant à intégrer ces deux modèles. Enfin, nous présentons une évaluation de nos résultats grâce à des indicateurs de fiabilité / The design of a railway transportation plan is a process achieved between two years and six months before it is put into service. The main phases in the design of a transportation plan are the line planning, the timetabling, the rolling stock and the crew scheduling.The design of the transportation plan can have many consequences on the quality of service: an inadequate frequency in station can cause a loss of passengers, sufficient number of seated places, robustness of the timetable in the face of small incidents... In dense area, as in the Ile-de-France region, all these elements must be taken into account as the transportation plan is designed.Today, SNCF Transilien designs its transportation plans by first taking into account the optimization of production resources (train paths, rolling stock units and drivers). However, today, the increase in resources implemented no longer improves the adequacy of the transportation plan to passengers’ demand. This design method no longer makes it possible to cope with the increase in the demand for mobility (+3% each year since 2000). This is why we must rethink the design of the transport plan by immediately integrating the passenger dimension. Our work focuses on issues of line planning and timetabling in a passenger-oriented approach. First, we present a multi-objective model for line planning. Then, we present a model of timetabling incorporating passenger route choice. Then, we initiate a method to integrate these two models. Finally, we present an evaluation of our results thanks to reliability indicators from the literature and a macroscopic simulation of the timetables
7

The GMOC Model : Supporting Development of Systems for Human Control

Tschirner, Simon January 2015 (has links)
Train traffic control is a complex task in a dynamic environment. Different actors have to cooperate to meet strong requirements regarding safety, punctuality, capacity utilization, energy consumption, and more. The GMOC model has been developed and utilized in a number of studies in several different areas. This thesis describes GMOC and uses train traffic control as the application area for evaluating its utility. The GMOC model has its origin in control theory and relates to concepts of dynamic decision making. Human operators in complex, dynamic control environments must have clear goals, reflecting states to reach or to keep a system in. Mental models contain the operator’s knowledge about the task, the process, and the control environment. Systems have to provide observability, means for the operator to observe the system’s states and dynamics, and controllability, allowing the operators to influence the system’s states. GMOC allows us to constructively describe complex environments, focusing on all relevant parts. It can be utilized in user-centred system design to analyse existing systems, and design and evaluate future control systems. Our application of GMOC shows that automation providing clear observability and sufficient controllability is seen as transparent and most helpful. GMOC also helps us to argue for visualization that rather displays the whole complexity of a process than tries to hide it. Our studies in train traffic control show that GMOC is useful to analyse complex work situations. We identified the need to introduce a new control strategy improving the traffic plan by supporting planning ahead. Using GMOC, we designed STEG, an interface implementing this strategy. Improvements that have been done to observability helped the operators to develop more adequate mental models, reducing use of cognitive capacity but increasing precision of the operative traffic plans. In order to improve the traffic controllers’ controllability, one needs to introduce and share a real-time traffic plan, and provide the train drivers with up-to-date information on the surrounding traffic. Our studies indicate that driver advisory systems, including such information, reduce the need for traffic re-planning, improve energy consumption, and increase quality and capacity of train traffic. / KAJT / FTTS
8

Décomposition de Benders pour la gestion opérationnelle du trafic ferroviaire / Benders decomposition for the real-time Railway Traffic Management Problem

Keita, Kaba 04 December 2017 (has links)
Dans plusieurs pays européens, la capacité de l’infrastructure est complètement exploitée aux heures de pointe et aux points critiques : une grande quantité de trains traversent ces points critiques dans un laps de temps très réduit. Dans cette situation le retard d’un train provoqué par un conflit de circulation peut se propager dans tout le réseau. Le problème de la gestion opérationnelle du trafic ferroviaire consiste à trouver les modifications des itinéraires et des ordonnancements des trains qui minimisent la propagation des retards. Dans cette thèse, nous proposons une approche de décomposition de Benders pour la formulation linéaire en nombres entiers à variables mixtes utilisée dans l’algorithme RECIFE-MILP. Après avoir constaté que l’approche de décomposition standard de Benders ne permet pas de trouver rapidement une solution de bonne qualité pour certaines instances du problème, nous étudions trois approches alternatives afin d’améliorer la performance de notre algorithme. Nous proposons d’abord une approche que nous appelons la reformulation réduite de Benders. Ensuite, nous introduisons des inégalités dans la formulation du problème maître de Benders. Finalement, nous scindons le processus de résolution en trois étapes au lieu de deux comme dans la décomposition standard de Benders. L'analyse expérimentale montre que la combinaison de la première et dernière approche surpasse l’algorithme original RECIFE-MILP dans la résolution de grandes instances sous certaines conditions. / In railway systems, during congested traffic situations, the infrastructure capacity is completely exploited for trains circulation. In these situations, when traffic is perturbed some trains must be stopped or slowed down for ensuring safety, and delays occur. The real-time Railway Traffic Management Problem (rtRTMP) is the problem of modifying trains route and schedule to limit delay propagation. In this thesis, we propose a Benders decomposition of a MILP-based algorithm for this problem, named RECIFE-MILP. After observing that the standard Benders decomposition (BD) does not allow the effective solution of rtRTMP instances, we study three possible approaches to improve the performance. Specifically, we first propose a modification of the problem reformulation which is typical of BD, obtaining what we call reduced BD. Then, we introduce some inequalities to the Benders master problem. Finally, we split the solution process in three steps rather than two as in the standard BD. As we show in a thorough experimental analysis, the combination of the first and last approaches outperforms the original RECIFE-MILP algorithm when tackling large instances with some specific features.
9

The Nordic Prediction Method For Railway Traffic Noise : Improvements of the current corrections forrailway bridges, switches and crossings

HELGADÓTTIR, KRISTÍN, BJÖRNSDÓTTIR, RAGNHEIÐUR January 2019 (has links)
Railway noise is a very important and growing health hazard in today´s society.Railway systems pass through towns and cities and create noise. When trainsride through or over railway bridges, switches and crossings the noise increasessubstantially, causing great annoyance to the residents in the area.At the present time, acoustic regulations exist in most countries and are set to achievea good environmental quality in residential areas, schools, hospitals, offices andhotels.A few calculation models exist for railway traffic noise, such as The NPM 1996,NORD2000 and Cnossos-EU. The NPM 1996 is currently used in Sweden to calculatenoise propagation from railway traffic. To uphold the regulations set, it is importantthat the method used is as precise as possible. All of these calculation modelsare based on several correction factors. Today, the current corrections for trackconditions, that is railway bridges, switches and crossings, are not very accurate andneed to be reconsidered.The aim of this project was to investigate and quantify the error of the NPM correctionfactors and give some indication of how they should be adjusted. This is done to makethe noise prediction from railway traffic more accurate and thus protect the residentsfrom these health risks.The specific objective was to perform significant amount of field measurements ofnoise from trains on different steel bridges, switches and crossings, as well as on afew concrete bridge according to the measurement standard Nordtest NT 098. Thefield work was carried out over the period March to May, when weather conditionsmet the criteria for field measurements, in and around the Stockholm area.The results obtained revealed that the correction factors for steel bridges andcrossings are considerably lower in the NPM than measured in this project. However,the correction factors for switches and concrete bridges are similar to the ones inthe NPM. In this thesis, a part of the correction factors have only been invalidatedto a degree. It has been shown that each bridge is unique and perhaps there is apossibility of finding similarities between some type of bridges. However, much moreiv |measurements are needed to see any correlation between each bridge type. Thus,further and more comprehensive measurements have to be carried out in order toestablish new accurate correction factors for track conditions in the Nordic PredictionMethod.
10

Méthodologie de réorganisation du trafic ferroviaire par analyse de sensibilité régionale : application à un incident sur infrastructure électrique / Railway traffic reorganization methodology by regional sensitivity analysis : application to an incident on electrical infrastructure

Saad, Soha 09 October 2019 (has links)
La qualité d'alimentation électrique d'un réseau ferroviaire peut être fortement affectée par l'indisponibilité d'un équipement électrique, que ce soit suite à un incident technique ou une opération de maintenance. Il est alors nécessaire de réduire le trafic prévu en ajustant les grilles horaires et les profils de vitesse, tout en conservant des performances d'exploitation optimales. Le but du travail présenté dans ce mémoire est de développer un outil d'aide à la décision pour assister les agents en charge de la réorganisation du trafic lors d'un incident sur infrastructure électrique. Le système étudié est complexe et son analyse repose sur des simulations coûteuses. Nous avons donc proposé une démarche en deux phases. Dans un premier temps, une analyse de sensibilité permet de détecter de manière efficace les variables d’ajustement du trafic les plus influentes. Après une analyse comparative entre différentes techniques, nous avons retenu l’analyse de sensibilité régionale par filtrage de Monte Carlo et test de KS, car cela permet de prendre en compte les contraintes opérationnelles, comme les niveaux de tension en ligne. La deuxième phase consiste à optimiser la solution en travaillant dans un espace de recherche de dimension réduite. Un ensemble de solutions Pareto optimales sont générées afin d’évaluer le meilleur compromis entre le critère principal qui est la densité de trafic et d’autres critères tels que les pertes ou les échauffements. Les techniques mises en œuvre ont abouti à la réalisation d’un prototype. Cet outil permet à l’ingénieur de définir les variables d’ajustement et les critères de performance du trafic. Il analyse ensuite l’influence des différentes variables d’ajustement et optimise le trafic par rapport aux critères définis. L’outil a été testé sur quatre cas d’étude correspondant à des portions de réseaux et à des trafics ferroviaires réels. / The power supply quality of a railway network can be strongly affected by the unavailability of electrical equipment, whether due to a technical incident or a maintenance operation. It is then necessary to reduce the expected traffic by adjusting the time schedules and speed profiles, while maintaining optimal operating performance. The purpose of the work presented in this thesis is to develop a decision support tool to assist the agents in charge of the reorganization of traffic during an incident on electrical infrastructure. The studied system is complex and its analysis is based on costly simulations. We therefore proposed a two-phase approach. As a first step, a sensitivity analysis can effectively detect the most influential traffic adjustment variables. After a comparative analysis between different techniques, we selected the regional sensitivity analysis by Monte Carlo filtering and KS test, because it allows us to take into account the operational constraints, like the tension levels in line. The second phase consists in optimizing the solution by working in a small research area. A set of Pareto-Optimal solutions are generated to evaluate the best trade-off between the main criterion "traffic density" and other criteria such as losses or overheating. The techniques implemented led to the production of a prototype. The tool allows the engineer to define traffic adjustment variables and traffic performance criteria. Then it analyzes the influence of the various adjustment variables and optimizes the traffic according to the defined criteria. The tool was tested on four case studies proposed by SNCF Réseau and corresponding to network segments and actual rail traffic.

Page generated in 0.0615 seconds