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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.
21

Redefining car-bus interchange to reduce traffic

Meek, Stuart January 2010 (has links)
Bus-based Park and Ride (P&R) schemes have become increasingly popular over the past 40 years in the UK, as a result of them being considered a positive traffic reduction policy by many, not least local authorities. There have nevertheless been concerns over the true effects of P&R. For instance, surveys of P&R users have long since revealed that up to a third transfer from conventional public transport. This induces car travel for the access portion of the P&R trip, which is generally large compared to the bus portion, owing to the edge-of-town location of P&R sites. Combined with the mileage effects of high-frequency bus services, evidence has suggested that P&R may thus result in an increase, compared to alternative travel behaviour, in the mean vehicle miles travelled (VMT) of its users. This thesis aims to investigate how UK bus-based P&R may be developed to reduce users VMT. As such, it applies to P&R the Characteristics Approach to Consumer Demand and delineates the attributes of interchange from which users derive utility. The research also develops this approach to consider the characteristics that affect the traffic impacts of P&R. The characteristics of P&R are adjusted to provide alternative concepts of interchange that aim to reduce VMT. These concepts are then examined to understand the level of utility that they are likely to provide. Local authorities perceptions of utility are examined initially, through a national survey which also looks at general attitudes towards P&R, its effects and its future. The city of Cambridge (UK) is selected as a case study in which an in-depth document analysis and interview survey of local stakeholders is carried out to understand the role of P&R in local policy and the implications of the implementation of alternative concepts of interchange. In this context, a survey of P&R users is also undertaken which considers the VMT effects of the current and alternative concepts of P&R as well as the change in the level of utility that would be derived from using them. It is concluded that local authorities generally consider P&R to be an effective policy in reducing car use whilst also playing important roles in the local economy and political arena. Yet the evidence on the Cambridge P&R scheme suggests that VMT is increased to a higher degree than previously proven. Alternative concepts of interchange are shown to offer some potentially significant benefits by reducing the VMT of users. Furthermore, some of the alternative concepts are also shown to offer benefits in terms of the utility that they may provide to the user, and the perceptions on this by local authorities. The VMT and utility results are combined to suggest that future implementation of interchange should consider operating feeder bus services into interchange sites (an intermediate solution offering some VMT benefits with relatively small resource requirements) or, operating a series of small interchange sites along main access routes to host cities (likely to require more resources but providing significant VMT benefits).
22

Original Short Stories

Horany, Sarah B. (Sarah Beth) 12 1900 (has links)
This thesis consists of three original short stories: "August Morning," "Weekend Idyll," and "Free Ride." In addition, an appendix has been added which contains "Hamilton House Roundabout," the original version of "Weekend Idyll." It is included to illustrate the dramatic changes that can occur in the writing process. "August Morning" focuses on a young man's struggle to gain his freedom from his family, particularly his overbearing father. Whether or not he succeeds is ultimately up to the reader. "Weekend Idyll" follows a young woman as she tries to live a dream she has long believed in. Ultimately, her vision is shattered. The final story, "Free Ride," centers on a hapless teenager who finds happiness only in the exhiliaration of racing. Ultimately, it kills him. I wrote stories rather than an analysis primarily for practical reasons. As a teacher I found an exercise in writing more readily transferrable to my classroom.
23

Contribuição à análise de especificações de componentes de rodovias e melhoria de qualidade de viagens / Contribution to the analysis of highways components specifications and ride quality improvement

Padula, Flávio Renato de Góes 11 January 2002 (has links)
Esta tese relata e discute informações obtidas em ações para tentar mostrar que o uso de conceitos sobre auditoria de qualidade e análise de correlação canônica pode contribuir para identificar itens que facilitem classificar tópicos para verificação de conformidade de especificações para construção ou controle de componentes de rodovias. O nível para qualidade de viagens pode ser analisado através da busca de uma expressão de necessidades e expectativas de motoristas e passageiros. Estudos sobre especificações de componentes de rodovias deveriam conter recomendações que contribuam para a qualidade de viagem, por entrosar conseqüências de uso de determinações técnicas com ações para atender às expectativas e necessidades dos que julgam a viagem. O uso da técnica e dos conceitos sobre auditoria, em conjunto com a análise de correlação canônica pode contribuir para classificar medidas ou contagens sobre variáveis que descrevem características físicas de rodovias do ponto de vista de melhoria de conforto e segurança a motoristas e passageiros. / This thesis reports and discusses information obtained from actions trying to show that the use of concepts on quality auditing and canonical correlation analysis can contribute to identify items to facilitate the classification of topics for verification on specifications conformity for the construction or the control of highways components. The level for ride quality can be analyzed through the search of an expression of needs and expectations of drivers and passengers. Studies about highway components specifications should contain recommendations to contribute for improving the ride quality, for gearing consequences of using technical determinations with actions to assist the expectations and needs of the ride judgers. The use of the auditing technique and concepts, together with the canonical correlation analysis can contribute to classify measures on variables that describe physical characteristics of highways on the point of view of comfort and safety improvement to drivers and passengers.
24

Contribuição à análise de especificações de componentes de rodovias e melhoria de qualidade de viagens / Contribution to the analysis of highways components specifications and ride quality improvement

Flávio Renato de Góes Padula 11 January 2002 (has links)
Esta tese relata e discute informações obtidas em ações para tentar mostrar que o uso de conceitos sobre auditoria de qualidade e análise de correlação canônica pode contribuir para identificar itens que facilitem classificar tópicos para verificação de conformidade de especificações para construção ou controle de componentes de rodovias. O nível para qualidade de viagens pode ser analisado através da busca de uma expressão de necessidades e expectativas de motoristas e passageiros. Estudos sobre especificações de componentes de rodovias deveriam conter recomendações que contribuam para a qualidade de viagem, por entrosar conseqüências de uso de determinações técnicas com ações para atender às expectativas e necessidades dos que julgam a viagem. O uso da técnica e dos conceitos sobre auditoria, em conjunto com a análise de correlação canônica pode contribuir para classificar medidas ou contagens sobre variáveis que descrevem características físicas de rodovias do ponto de vista de melhoria de conforto e segurança a motoristas e passageiros. / This thesis reports and discusses information obtained from actions trying to show that the use of concepts on quality auditing and canonical correlation analysis can contribute to identify items to facilitate the classification of topics for verification on specifications conformity for the construction or the control of highways components. The level for ride quality can be analyzed through the search of an expression of needs and expectations of drivers and passengers. Studies about highway components specifications should contain recommendations to contribute for improving the ride quality, for gearing consequences of using technical determinations with actions to assist the expectations and needs of the ride judgers. The use of the auditing technique and concepts, together with the canonical correlation analysis can contribute to classify measures on variables that describe physical characteristics of highways on the point of view of comfort and safety improvement to drivers and passengers.
25

Carbody and Passengers in Rail Vehicle Dynamics

Carlbom, Pelle January 2000 (has links)
The carbody plays an important role in rail vehicle dynamics.This thesis aims atdeveloping validated modelling methods tostudy its dynamics, how it is excited on trackand how itinteracts with the passengers. The primary interest is ridecomfort,considering vibrations up to 20 Hz. In this frequencyrange, the structural flexibility ofthe carbody is of majorconcern. The models are intended for use intime-domainsimulation, calling for small-sized models to reducecomputational time and costs. Keyparameters are proposed toselect carbody eigenmodes for inclusion in a flexiblemultibodymodel, and to quantify the interaction between passengers andcarbody. Extensive comparisons between measurements and correspondingsimulations arecarried out in a case study. On-track measurementsare performed to obtain operatingdeflection shapes and powerspectral densities of the accelerations in the carbody.Thecomplete vehicle is modelled using the pieces of softwareGENSYS (flexible multibodymodel) and ANSYS (finite element modelof the carbody). Actual, measured trackirregularities are used asinput. In order to investigate the influence of passengerload,experimental modal analysis of the carbody is performed withand without passengers.Also, amplitude dependence is examined.Simple models, based on human-body modelsfrom literature, of thepassenger-carbody system are proposed and validated.Verticalseating dynamics is considered. The models areimplemented and tested in the casestudy. Finally, ideas on modelreduction and approximation are presented and applied. The main conclusions drawn from the study are that     the structural flexibility of the carbody must be takeninto account when predictingvertical vibration comfort. It ispossible to predict which carbody modes that willcontributemost to the vibrations.     the carbody dynamical properties depend on the excitationamplitude.     passengers and carbody interact significantly.- theproposed models describe the interaction quite well. Theproposed passenger-carbodymodel gives an upper boundary on theinteraction.     the proposed passenger-seat-carbody model can be used tostudy the influence of theseat parameters on the interaction.This merits to be investigated further, however. <b>Keywords</b>: Carbody, Experimental modal analysis, Human-bodydynamics, Modelreduction, Multibody dynamics, Operatingdeflection shapes, Rail-vehicle dynamics,Ride comfort, Seatingdynamics, Structural dynamics.
26

Carbody and Passengers in Rail Vehicle Dynamics

Carlbom, Pelle January 2000 (has links)
<p>The carbody plays an important role in rail vehicle dynamics.This thesis aims atdeveloping validated modelling methods tostudy its dynamics, how it is excited on trackand how itinteracts with the passengers. The primary interest is ridecomfort,considering vibrations up to 20 Hz. In this frequencyrange, the structural flexibility ofthe carbody is of majorconcern. The models are intended for use intime-domainsimulation, calling for small-sized models to reducecomputational time and costs. Keyparameters are proposed toselect carbody eigenmodes for inclusion in a flexiblemultibodymodel, and to quantify the interaction between passengers andcarbody.</p><p>Extensive comparisons between measurements and correspondingsimulations arecarried out in a case study. On-track measurementsare performed to obtain operatingdeflection shapes and powerspectral densities of the accelerations in the carbody.Thecomplete vehicle is modelled using the pieces of softwareGENSYS (flexible multibodymodel) and ANSYS (finite element modelof the carbody). Actual, measured trackirregularities are used asinput. In order to investigate the influence of passengerload,experimental modal analysis of the carbody is performed withand without passengers.Also, amplitude dependence is examined.Simple models, based on human-body modelsfrom literature, of thepassenger-carbody system are proposed and validated.Verticalseating dynamics is considered. The models areimplemented and tested in the casestudy. Finally, ideas on modelreduction and approximation are presented and applied.</p><p>The main conclusions drawn from the study are that</p><p>    the structural flexibility of the carbody must be takeninto account when predictingvertical vibration comfort. It ispossible to predict which carbody modes that willcontributemost to the vibrations.</p><p>    the carbody dynamical properties depend on the excitationamplitude.</p><p>    passengers and carbody interact significantly.- theproposed models describe the interaction quite well. Theproposed passenger-carbodymodel gives an upper boundary on theinteraction.</p><p>    the proposed passenger-seat-carbody model can be used tostudy the influence of theseat parameters on the interaction.This merits to be investigated further, however.</p><p><b>Keywords</b>: Carbody, Experimental modal analysis, Human-bodydynamics, Modelreduction, Multibody dynamics, Operatingdeflection shapes, Rail-vehicle dynamics,Ride comfort, Seatingdynamics, Structural dynamics.</p>
27

On Objective Measures for Ride Comfort Evaluation

Strandemar, Katrin January 2005 (has links)
<p>An essential tool in the truck development process is the ability to quantify and grade vehicle dynamic behavior. Today this is performed either through subjective or objective tests. Subjective tests have the disadvantage that numerous factors influence test drivers’ opinions while objective measures have the advantage of repeatability. However, objective methods of today are often only able to provide a rough grading of vehicles. The main objective with this thesis is to develop more sensitive objective methods for ride comfort evaluation.</p><p>An effective test procedure to measure driver perception sensitivity to small differences in vehicle ride is suggested and utilized. The driver sensitivity is tested on dynamic behavior that is typically graded in vehicle development. Cab motions from a truck are first measured and then recreated in a simulator where a test driver is seated. The perception threshold for small changes in typical vehicle motion is established in this way for each test person.</p><p>The perception sensitivity tests indicate that humans are quite sensitive to transients in vehicle motion. One problem with many common vehicle ride measures is that the impact of transient behavior is small due to the averaging used to condense the measurement data into scalar measures. A new evaluation method for ride comfort, with influences from the well known handling diagram, is suggested. This method has four main advantages: it is fairly simple to interpret, it shows the absolute vibration level, it considers transient events separately and it shows changes in vehicle character with increasing excitation. Promising results from both measurements and simulations are derived.</p><p>New technology has made it possible to vary vehicle suspension parameters during vehicle ride. In order to prescribe different damping for different vehicle modes, modal motion estimates are needed. A system identification approach is suggested. It yields improved estimates of vehicle modal motion compared to previous work.</p>
28

Fault Ride-Through Capability of Doubly-Fed Induction Generators Based Wind Turbines

ABOBKR, ABOBKR 14 March 2013 (has links)
Due to growing concerns over climate change, more and more countries are looking to renewable energy sources to generate electricity. Therefore, wind turbines are increasing in popularity, along with doubly-fed induction machines (DFIGs) used in generation mode. Current grids codes require DFIGs to provide voltage support during a grid fault. The fault ride-through (FRT) capability of DFIGs is the focus of this thesis, in which modifications to the DFIG controller have been proposed to improve the FRT capability. The static synchronous compensator (STATCOM) controller has been applied with proposed method to study its influence on the voltage at the point of common coupling (PCC). The proposed method was also compared with other FRT capability improvement methods, including the conventional crowbar method. The simulation of the dynamic behaviour of DFIG-based wind turbines during grid fault is simulated using MATLAB/Simulink. The results obtained clearly demonstrate the efficacy of the proposed method.
29

A ride in stereovision / A ride in stereovision

Persson, Mattias, Laszlo, Johan January 2005 (has links)
Vårt magisterarbete är en 3D-animation som ska simulera en bergochdalbana. Vår uppgift har varit att ta reda på hur man genom illusioner kan lura människans hjärna att se djup även då bilden är helt platt. Vårt främsta verktyg vi använt oss av är glasögon med röd- och cyanfärgade filter. Till vår produktion har vi anlitat andra studenter för att komponera musik och mixa 5.1-ljud. Allt för att öka upplevelsen ännu mer. / Detta är en reflektionsdel till en digital medieproduktion. Mattias e-mail: mape78@gmail.com, Johan e-mail: atra@telia.com
30

Problèmes de transport à la demande avec prise en compte de la qualité de service / Dial-a-Ride problems which take into account the quality of service

Chassaing, Maxime 04 December 2015 (has links)
Cette thèse porte sur la modélisation et la résolution de différents problèmes de tournées de véhicules et plus particulièrement sur des problèmes de transport de personnes. Ces problèmes, demandent, entre autre, de respecter une qualité de service minimale pour les solutions proposées. Pour résoudre ces problèmes, plusieurs méthodes d'optimisation de type métaheuristique sont proposées pour obtenir des solutions de bonne qualité dans des temps raisonnables. Trois problèmes sont traités successivement : le DARP, le TDVRP, le SDARP. Le premier est un problème de transport à la demande (DARP - Dial-A-Ride Problem) qui est le problème de transport de personnes le plus connu de la littérature. Il est proposé dans ce chapitre une méthode de type ELS qui a été comparée aux meilleures méthodes publiées. Les tests montrent que la méthode ELS est compétitive en termes de temps de calcul et de qualité des résultats. Le deuxième problème est une extension du problème de tournées de véhicules (VRP - Vehicle Routing Problem) dans lequel les temps de trajet entre les sommets varient au cours de la journée (TDVRP - Time Dependent Vehicle Routing Problem). Dans ce problème, une distinction existe entre les temps de conduite et les temps de travail des chauffeurs. La différence entre les deux correspond aux temps de pause. Ils sont utilisés ici durant les tournées pour éviter aux chauffeurs de conduire durant les périodes à fort ralentissement du trafic. La méthode proposée permet entre autre de positionner stratégiquement ces pauses afin de réduire le temps de conduite et de proposer de nouvelles solutions. Le dernier problème traité concerne la résolution d'un DARP stochastique. Dans ce problème, les temps de trajet entre les clients ne sont plus déterministes, et ils sont modélisés par une loi de probabilité. L'objectif est de déterminer des solutions robustes aux fluctuations des temps de trajets sur les arcs. Une première approche a permis de calculer des solutions robustes qui ont une probabilité importante d'être réalisables, une seconde approche a permis de générer un ensemble de solutions offrant un équilibre entre la robustesse et le coût. / In this thesis, we are interested in modeling and solving various vehicle routing problems (VRP), especially passenger transportation problems. These problems aim at finding solutions which guarantee a required quality of service. Several metaheuristics are proposed to obtain high quality solutions within reasonable time. Three problems are addressed: the Dial-A-Ride Problem (DARP), the Time-Dependent Vehicle Routing Problem (TDVRP) and the Stochastic DARP (SDARP). The DARP is a well-known on-demand transportation problem. We propose an Evolutionary Local Search (ELS) method. It relies on a new randomized constructive heuristic and on adaptive probabilities for selecting neighborhood structures. This approach is compared with existing methods on classical instances. Results show the interest of the proposed method. The TDVRP is an extension of VRP in which the transportation time varies throughout the day. The driving time is separated from the drivers working time and the difference corresponds to the resting time. The resting time is used to avoid driving during highly congested periods. The proposed method set these resting times in order to reduce the driving time. Hence new solutions avoiding congestion as much as possible are proposed. In the SDARP, the travel time between clients is stochastic and thus follows a probability distribution. The objective is to compute robust solutions, i.e. solutions which handle variations of the transportation time. Two approaches are proposed for this problem. The first one produces robust solutions that have a significant probability of staying feasible. The second one generates a set of compromise solutions, balancing the robustness and the cost.

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