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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.
91

Mathematical modeling and methods for rescheduling trains under disrupted operations / Modélisation mathématique et méthodes de résolution pour le problème de réordonnancement de plan de circulation ferroviaire en cas d'incidents

Acuña-Agost, Rodrigo 15 September 2009 (has links)
En raison de problèmes opérationnels et d’autres événements inattendus, un grand nombre d’incidents se produisent quotidiennement dans les systèmes de transport ferroviaire. Certains d’entre eux ont un impact local, mais quelques fois, essentiellement dans les réseaux ferroviaires plus saturés, des petits incidents peuvent se propager à travers tout le réseau et perturber de manière significative les horaires des trains. Dans cette thèse doctorale, nous présentons le problème de réordonnancement de plan de circulation ferroviaire en cas d’incident comme la problématique de créer un plan de circulation provisoire de manière à minimiser les effets de la propagation des incidents. Ce travail est issu du projet MAGES (Module d’Aide à la Gestion des Sillons) qui développe des systèmes de régulation pour le trafic ferroviaire. Nous présentons deux modèles différents qui permettent de trouver des solutions à ce problème : Programmation Linéaire en Nombres Entiers (PLNE) et Programmation Par Contraintes (PPC). Du fait de la nature fortement combinatoire du problème et de la nécessité de répondre rapidement aux incidents, il ne paraît pas raisonnable d’envisager une résolution exacte. Les méthodes correctives proposées consistent donc à explorer un voisinage restreint des solutions : right-shift rescheduling; une méthode basée sur des coupes de proximité; une méthode d’analyse statistique de la propagation des incidents (SAPI) et un méthode basée sur la PPC. Additionnellement, certaines de ces méthodes ont été adaptées sous forme d’algorithmes itératifs avec l’objectif d’améliorer progressivement la solution quand le temps d’exécution le permet. SAPI est une des principales contributions de cette thèse. SAPI intègre les concepts de right-shift rescheduling avec les coupes de proximité. Du fait de la taille des réseaux en jeu et du nombre de circulations, les phénomènes complexes de propagation d’un incident font qu’il est très difficile de connaitre de manière précise les événements qui seront affectés. Toutefois, il est tout de même envisageable d’évaluer la probabilité qu’un événement soit affecté. Pour calculer cette probabilité, un modèle de régression logistique est utilisé avec des variables explicatives dérivées du réseau et des circulations. Diverses variantes de ces méthodes sont évaluées et comparées en utilisant deux réseaux ferroviaires localisés en France et au Chili. À partir des résultats obtenus, il est possible de conclure que SAPI est meilleure que les autres méthodes en terme de vitesse de convergence vers l’optimum pour les instances de petite taille et moyenne alors qu’une méthode coopérative PNLE/PPC est capable de trouver des solutions pour les instances de plus grande taille. La difficulté de comparer SAPI avec d’autres méthodes présentées dans la littérature nous a encouragés à appliquer la méthode à un autre problème. Ainsi, cette méthodologie a été également adaptée au problème de réordonnancement de passagers, vols et appareils (avions) en cas de perturbations, problème originalement proposé dans le contexte du Challenge ROADEF 2009. Les résultats montrent que SAPI est efficace pour résoudre ce problème avec des solutions au-dessus de la moyenne des équipes finalistes en obtenant la troisième place du challenge / For operational and unpredictable reasons, many small incidents occur day after day in rail transportation systems. Most of them have a local impact; but, in some cases, minimal disruptions can spread out through the whole network and affect significantly the train schedules. In this Thesis, we present the Railway Rescheduling Problem (RRP) as the problem of finding a new schedule of trains after one or several incidents by minimizing some measure of the effect, e.g., the total delay. This Thesis has been developed in the context of the MAGES project that builds mathematical models and algorithms for optimizing railway operations. Two complementary formulations are proposed to model this problem: Mixed-Integer Programming (MIP) and Constraint Programming (CP). Because of the impossibility of solving real-world instances by using standard solvers, we propose several solutions methods: right-shift rescheduling; a MIP-based local search method; Statistical Analysis of Propagation of Incidents (SAPI); and a CP-based approach. Some methods are presented in different versions by extending them to iterative approaches. Among them; SAPI is one of the major contributions of this Thesis. It integrates the concepts of right-shift rescheduling and the MIP-based local search method by fixing integer variables and adding linear inequalities (cuts). SAPI assumes that the effects of disruptions can be propagated to other upcoming events. Nevertheless, this propagation is not uniform to all events and could be forecasted by a statistical analysis. Different versions of the methods are compared in two different networks located in France and Chile. From the results, it is possible to conclude that SAPI finds good solutions faster than the other methods, while a cooperative CP/MIP approach that takes advantage of both formulations seems to be appropriate for large instances. Because of the difficulty to compare SAPI to other methods presented in the literature due to lack of public benchmarks, we applied it to another problem where public instances are available. Hence, the methodology was adapted and applied to the problem of rescheduling passengers, flights, and aircraft under disrupted operations in the context of the ROADEF challenge 2009. SAPI took the third position on this competition, showing that the method seems to be effective solving such type of problems efficiently
92

Combinaison de méthodes formelles pour la spécification de systèmes industriels / Coupling of formal methods for industriel systems specification

Fayolle, Thomas 27 June 2017 (has links)
La spécification d’un système industriel nécessite la collaboration d’un ingénieur connaissant le système à modéliser et d’un ingénieur connaissant le langage de modélisation. L'utilisation d'un langage de spécification graphique, tel que les ASTD (Algebraic State Transition Diagram), permet de faciliter cette collaboration. Dans cette thèse, nous définissons une méthode de spécification graphique et formelle qui combine les ASTD avec les langages Event-B et B. L’ordonnancement des actions de la spécification est décrit par les ASTD et le modèle de données est décrit dans la spécification Event-B. La spécification B permet de vérifier la cohérence du modèle : les événements Event-B doivent pouvoir être exécutés lorsque les transitions associées doivent l’être. Un raffinement combiné des ASTD et d’Event-B permet la spécification incrémental du système. Afin de valider son apport, la méthode de spécification a été utilisée pour la spécification de cas d’études / Specifying industrial systems requires collaboration between an engineer that knows how the system works and an engineer that know the specification language. Graphical specification languages can help this collaboration. In this PhD Thesis a method is defined that combines ASTD (Algebraic State Transition Diagram), a formal graphical notation, with B and Event-B langagues. The ordering of actions is specified using ASTD and the data model is specified using Event-B. B specification is used to verify the consistency of the model : Event-B events have to be executed when the corresponding transitions have to be executed. A combined refinement allows to incrementaly design the system
93

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.
94

Ekonomické aspekty akcesibility s využitím osobní železniční dopravy / The Economic Aspects of Accessibility with Use of Public Railway Traffic

Plencnerová, Zuzana January 2009 (has links)
This thesis deals with the evaluation of the investment efficiency to the traffic buildings. Theoretical part describes the history of the traffic sector and the railway traffic, the ownership and financing of the railway infrastructure. Next section describes the characteristic of railway corridors, basic principles of their modernization and optimizations and methods for the evaluation of investment efficiency. In practical part is focused on design of an own methodology for the evaluation of investment efficiency to the traffic building according to savings of passengers' time. The investment efficiency to the railway corridors is assessed using proposed methodology.
95

Rozvoj vysokorychlostní železniční dopravy ve Španělsku / Development of high-speed rail transport in Spain

Fujdlová, Simona January 2011 (has links)
This thesis describes the position of rail transport in Spain and focuses mainly on the current development of high-speed rail transport. Attention is paid to the AVE system, which is operated by the newly built infrastructure, but also to the other high-speed trains to run on conventional lines with Iberian gauge. The aim is to highlight the progress achieved in this area, capture a network built and planned high-speed lines, the transition to neighboring states and the process of integration of Spain into the Trans-European transport networks. In analyzing the tariff policy, the paper deals with basic and preferential tariffs applied by Renfe Operadora in the sphere of high-speed long-distance passenger trains.
96

Se eles são livres ou escravos : escravidão e trabalho livre nos Canteiros da Estrada de São Francisco: Bahia, 1858-1863 / If they are free or slaves : slavery and free labor in the San Francisco Railway: Bahia, 1858-1863

Souza, Roberio Santos, 1978- 22 August 2018 (has links)
Orientador: Silvia Hunold Lara / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Filosofia e Ciências Humanas / Made available in DSpace on 2018-08-22T10:19:08Z (GMT). No. of bitstreams: 1 Souza_RoberioSantos_D.pdf: 2979635 bytes, checksum: 7e864f5ab8942b61da96d67123db4380 (MD5) Previous issue date: 2013 / Resumo: A tese trata dos trabalhadores das obras de construção da ferrovia que ligava Salvador a Alagoinhas, pela Bahia and San Francisco Railway Company, no período entre 1858-1863 na Província da Bahia. De um modo geral, a sua estrutura está organizada em cinco capítulos que correspondem à análise da atuação dos empresários ingleses, das formas de recrutamento da mão-de-obra, da constituição formal das relações de trabalho e das várias experiências compartilhadas pela multidão de homens imigrantes e nacionais, livres, libertos e escravos engajados nas obras da ferrovia baiana. Foram utilizadas, principalmente, fontes administrativas da companhia inglesa responsável pelas obras, completadas pela correspondência entre os engenheiros e as autoridades provinciais bem como documentos policiais e iconográficos. A historiografia brasileira geralmente caracteriza as últimas décadas do século XIX como um período de "transição do trabalho escravo para o trabalho livre e assalariado". Esta análise normalmente concebe a escravidão como oposta à experiência da liberdade ou enfatiza o trabalho escravo como antagônico ao trabalho livre e assalariado no século XIX. De modo diverso, esta tese ressalta que as fronteiras entre a escravidão e a liberdade podiam ser muitas vezes tênues na sociedade escravista oitocentista, tornando as experiências de trabalhadores escravos, libertos e livres pobres ambíguas, indeterminadas e precárias. Apesar de considerar as diferenças de condição entre esses trabalhadores, a tese argumenta que as experiências comuns de exploração bem como as ambiguidades e a precariedade da vida em liberdade forjaram, naquele contexto, uma identidade social entre os livres e os escravizados / Abstract: This thesis examines the laborers who took part in the construction of the railroad that connected Salvador to Alagoinhas, by the Bahia and San Francisco Railway Company, in the period from 1858-1863 in the province of Bahia. Overall, its structure is organized into five chapters that correspond to an analysis of the actions of the English businessmen, the forms of recruitment of manpower, the formal establishment of the working relationships, and the various shared experiences of the multitude of immigrant and national men -- free, freed, and slaves -- involved in the works of the Bahian railroad. We use primarily administrative records of the English company responsible for the works, supplemented by the correspondence between the engineers and the provincial authorities, as well as police documents and iconographic records. The Brazilian historiography generally characterizes the last decades of the 19th century as a period of "transition from slave labor to free and salaried labor". This analysis normally conceives of slavery as the opposite of the experience of liberty or emphasizes slave labor as antagonistic to free and salaried labor in the 19th century. In contrast, this thesis stresses that the frontiers between slavery and freedom could often be tenuous in the slaveholding society of the 1800s, making the experiences of slave laborers, freed laborers, and poor free laborers ambiguous, indeterminate and precarious. Despite considering the differences in condition between these workers, the thesis argues that the common experiences of exploitation, as well as the ambiguities and the precariousness of life in freedom, forged, in that context, a social identity between the free and the enslaved / Doutorado / Historia Social / Doutor em História
97

AN EMPIRICAL STUDY TO REVIEW BUSINESS MODEL THEORY IN THE DANISH RAILWAY SECTOR

Roldsgaard, Kasper Vilstrup 07 July 2014 (has links)
PURPOSE:! The! purpose! is! to! explore! the! basic! assumptions! for! innovating! the! Danish! railway! operator¿s! historic! business!model!in! an! unprecedented! institutional!crisis.!! METHOD:! A! management! survey! collects! 22,729! responses! from! 368! managers! (80%!of!the!managers!in!the!Danish!railways!with!average!seniority!of!15! years)! to! explore! these! basic! assumptions! to! specify! the! areas! of! leadership! that! have! a! significant! impact! on! facilitating! innovation! of! business!models!in!times!of!crisis.! RESULTS:! Successful!leadership!in!a!crisis!depends!on! the!articulation!of! the!basic! assumptions!and!challenges!for!the!development!of!the!current!business! model.! It! is! not! enough! to! make! goals! for! the! future,! as! the! related! challenges! should! also! be! articulated.! A! core! task! for! strengthening! the! development! in! the! railway! sector! is! to! prioritize! new! infrastructure! projects! to! innovate! the! existing! railway! operations! gradually,! rather! than!starting!new!business!ventures.! ORIGINALITY/VALUE:! Management!studies!in! times!of!crisis!are!rare.!Furthermore,! the!causes! of!the!institutional!crisis!in!the!Danish!railway!sector!have!until!now!not! been! studied! from! a! management! perspective! based! on! the! managers¿! understanding! of! the! factors! affecting! the! innovation! management! of! a! business! model! in! crisis.! The! doctoral! thesis! identifies! some! emerging! areas! of! cognitive! leadership! that! have! not! yet! received! sufficient! attention! in! the! literature! on! business! models,! but! nonetheless! the! company!managers!believe! that! the!areas!of!cognitive!leadership!have!a! significant! impact! on! the! survival! of! the! organization! and! its! future! success.! / Roldsgaard, KV. (2014). AN EMPIRICAL STUDY TO REVIEW BUSINESS MODEL THEORY IN THE DANISH RAILWAY SECTOR [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/38615 / TESIS
98

Crisis, New Imperialisms, and Accumulation by Dispossession: The Case of the Pakistan Railways

Khan, Sher Ali 08 1900 (has links)
My research examines the three interrelated concepts of crisis; new imperialisms, spatial-temporal fix and accumulation by dispossession (ABD) stemming from the work of David Harvey as a way to understand the contested history of the Pakistan Railways. For the first thirty odd years after Pakistan's inception in 1947, the railways, a state-owned institution, was the primary mode of transport for the public, cargo, and workers. Alongside basic infrastructure, the railways had a vast network of hospitals, schools, workers' colonies and an array of physical infrastructure connected to production, operations and other aspects of the economy. The systematic ransack and decline of the Pakistan Railways reached its peak in 2010. Despite several attempts throughout the 1990s by successive democratic and military-led governments backed by the IMF/World Bank in 2015, it was announced that Pakistan railways would be revived under the banner of the 46 billion dollar China Pakistan Economic Corridor (CPEC) as part of the changing geopolitical context of growing regional connectivity and new Chinese imperialism. By examining the processes that underlie ABD, such as spatial-temporal fix, the following research shows that these processes not only reflect a shift of resources away from the public domain, but in Pakistan also entailed the transformation of the railways from a utilitarian welfare organization to an entity that facilitates looting, unbundling, and dispossession of shared resources and infrastructure.
99

Planification robuste des roulements d’engins dans le domaine ferroviaire / Robust railway rolling-stock planning

Tréfond, Sabine 17 March 2014 (has links)
Cette thèse est consacrée à la planification robuste du matériel roulant ferroviaire dans un contexte de transport de voyageurs régional. Il s'agit de déterminer pour chaque engin une suite de trajets à réaliser sur une période donnée de façon à résister au mieux aux aléas pouvant apparaître en opérationnel. Dans ce but, nous proposons une définition et une caractérisation de la robustesse par des indicateurs propres au contexte d'étude. Nous abordons le problème par une approche structurelle différente des approches robustes classiques qui permet d'agir sur la structure d'une solution en fonction des indicateurs définis. Trois méthodes sont alors mises en œuvre dans le cadre de ce travail. Une résolution approchée par une heuristique gloutonne et une recherche locale permet d'obtenir des solutions rapidement. Une méthode de résolution approchée par génération de colonnes a été développée afin de prendre en compte plus de contraintes de façon intégrée. Une méthode basée sur un programme linéaire en nombres entiers résolu exactement traite un problème plus général. Afin de limiter le coût de la robustesse, ces méthodes sont basées sur un existant à SNCF répondant au problème de planification des ressources matérielles à coûts de production minimaux. Un outil de simulation du comportement des solutions en situation perturbée permet de comparer les solutions entre elles par évaluation des indicateurs de robustesse. Des expérimentations sur des instances réelles ont prouvé la pertinence des approches et ont mené à l'industrialisation d'un prototype. / This thesis deals with robust rolling-stock planning problems for passenger regional trains. It consists in building robust rolling-stock schedules to operate trains under technical constraints while anticipating operational disturbances that can occur. First of all, we define indicators to characterize robustness in context. We use these indicators to have an effect on solutions that we build. This structural approach is unusual compared to classical robust optimization approaches. We have implemented three methods to solve the problem. A sequential heuristic method enhanced by a local search gives solutions quickly. A column-generation method calculates approximate solutions.An integer linear program is solved exactly to obtain solutions to a global problem. These methods are based on an existing tool at SNCF that optimizes the rolling-stock planning problem to assure optimal production costs. A simulation tool evaluates robustness indicators to compare solutions. Tests on real instances have proved the relevance of the approaches and have lead to the use of a prototype in production
100

Obnova zaniklých cest- tratí mezi Moravou a Dolním Rakouskem / Restoration of vanished roads and railways connetcting Moravia to Lower Austria

Chlupová, Jana January 2017 (has links)
The project deals with the restoration of the railway connecting Hevlin and Laa an der Thaya. The renovation of the railway station in Hevlin is divided into individual stages. The first stage consists of conversion of the Art Nouveau expedition building in the museum. In the next stage a platform will be built and adjacent sites will be re-arranged. An important step at this phase is the roof construction for the future expedition building. The roofing will serve for summer cultural events or markets. This new utilization will benefit from free flat space of the platform. The last step is completion of perimeter walls and the building will serve as a railway station. After construction of bridge the railway connection between Hevlin and Laa an der Thaya will be reopened. Another railway between Brno and Vienna will be created as well. The aim of the study is to strengthen relation of neiborougs from South Moravia and LowerAustria.

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