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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.
121

Transit oriented development and neighborhood change along the light rail system : the social equity impact of the Metro Blue line in Los Angeles

Sung, Seyoung 06 October 2014 (has links)
This report examines how the neighborhoods along the Metro Blue line have changed over the past two decades, and reflects on the current emerging issue in Transit oriented development (TOD), which is promoting equitable transit neighborhoods. The primary study area includes the route of the Metro Blue line through Los Angeles County where the most economically disadvantaged and marginalized communities are located in the county. In order to investigate the impact of the rail line effectively, the concept of Walksheds are used as the units of analysis, which is defined as the area within a half-mile walking distance from the transit station. Focusing on social equity impact of the transit system operation, the comparison analysis between Los Angeles County and the twenty-two Walksheds of each station in the line evaluates the changes in the close-by neighborhoods while also looking at various social demographic indicators that can reflect demographic shifts using decennial Census data of 1990, 2000, and 2010. While looking at the change through time series data analysis vertically, the performance of each station area is examined horizontally. Therefore, comparative analysis is conducted in four stages to figure out the extent to which the neighborhoods have changed, how rapidly the change occurred and whether the neighborhood change occurred in a positive way or not. The result from the four comparative analyses indicates that the Metro Blue line did not work as a catalyst for promoting economic opportunity in the region in spite of the initial expectations of its advocates. In the beginning of the rail operation of 1990, the neighborhoods along the rail line were excluded and poverty was widespread in the region. However, even after two decades, the twenty-two Walksheds along the Metro Blue Line still remain as undesirable places to live and marginalized as compared to the rest of the county. Moreover, the neighborhood change in the twenty-two Walksheds is negatively linked to the Walksheds based on the result of the comparative analysis. / text
122

Ground borne vibrations from high speed trains

Connolly, David January 2013 (has links)
A consequence of high speed rail transportation is the generation of elevated ground borne vibrations. This thesis presents several original contributions towards the prediction of these vibrations. Firstly, a new three dimensional finite element model capable of vibration prediction was developed. Its main feature was its ability to model complex track geometries while doing so through a fully coupled vehicle-tracksoil system. Model output was compared to experimental results obtained during this thesis and also to independent data sets. It was shown to predict velocity time histories, vibration frequency spectrums and international vibration descriptors with high accuracy. An appraisal of the suitability of a finite difference time domain modelling approach for railway vibration prediction was also undertaken. This resulted in the development of a new ‘higher order’ perfectly matched layers absorbing boundary condition. This condition was found to offer higher performance in comparison to current alternative absorbing boundary conditions. Field work was then undertaken on high speed lines with varying embankment conditions in Belgium and England. Vibration data was recorded up to 100m from each track and geophysical investigations were performed to determine the underlying soil properties. The results were used for numerical model validation and also to provide new insights into the effect of various embankment conditions on vibration propagation. It was found that embankments generate higher frequency excitation in comparison to nonembankment cases and that cuttings generate higher vibration levels than noncuttings. Once validated the finite element model was used to provide new insights into the effect of train speed, embankment constituent materials and railway track type on vibration levels. It was found that the shape and magnitude of ground vibration increased rapidly as the train’s speed approached the Rayleigh wave speed of the underlying soil. It was also found that ballast, slab and metal tracks produced similar levels of vibration and that stiffer embankments reduced vibration levels at distances near and far from the track. Two vibration mitigation techniques were also explored through numerical simulation. Firstly, an analysis was undertaken to determine the ability of a new modified ballast material to actively isolate vibration within the track structure. Secondly, wave barrier geometries were investigated to optimise their performance whilst minimising cost. It was found that barrier depth was the most influential parameter, whereas width had little effect. Additionally, geometry optimisation was found to result in a 95% cost saving in comparison to a base case. Using a vast array of results generated using the previously developed finite element model, a new empirical prediction model was also developed, capable of quickly assessing vibration levels across large sections of track. Unlike currently available empirical models, it was able to account for soil properties in its calculation and could predict a variety of international vibration metrics. It was shown to offer increased prediction performance in comparison to an alternative empirical model.
123

Economics of railway safety rules

Tsai, Ming-Chih January 1998 (has links)
No description available.
124

Srovnání vnitrostátních a mezinárodních železničních tarifů / Comparison of national and international rail tariffs

Bolech, Filip January 2010 (has links)
The basis of this work is a description of the different tariff systems in both national and international rail transport. The section devoted to national tariffs compares the differences in fares between the periods 2006/2007, 2007/2008 and 2009/2010. The emphasis on ordinary fare is devoted to the transition from more than one kilometre zones to one kilometre zones. The conditions necessary to make the CD business offers convenient to purchase are also analyzed. International fares are compared by the price per tariff kilometre. Most discounts are available only if the return journey. The main product is the eTiket. Travelers from Czech Republic to the border regions of Germany and Poland can use several types of international ticket networks.
125

An?lise dos gases da exaust?o em um motor diesel com inje??o Common Rail alimentado com diesel, biodiesel e suas misturas

Costa, Joel de Oliveira 31 October 2017 (has links)
Submitted by PPG Engenharia e Tecnologia de Materiais (engenharia.pg.materiais@pucrs.br) on 2017-12-26T10:44:28Z No. of bitstreams: 1 Joel_de_Oliveira_Santos_DIS.pdf: 2391365 bytes, checksum: 494fe700a3624e9b996ee073b4bc0283 (MD5) / Approved for entry into archive by Caroline Xavier (caroline.xavier@pucrs.br) on 2017-12-26T19:01:58Z (GMT) No. of bitstreams: 1 Joel_de_Oliveira_Santos_DIS.pdf: 2391365 bytes, checksum: 494fe700a3624e9b996ee073b4bc0283 (MD5) / Made available in DSpace on 2017-12-26T19:06:12Z (GMT). No. of bitstreams: 1 Joel_de_Oliveira_Santos_DIS.pdf: 2391365 bytes, checksum: 494fe700a3624e9b996ee073b4bc0283 (MD5) Previous issue date: 2017-10-31 / The presente work aims to evaluate exhaust gas emissions and particulate matters in a diesel cycle engine. A Cummins ISB Maxi Power (EURO III) Ford F250 pickup truck with electronic commom rail fuel injection system was used to identify which blend achieves the best environmental performance without compromising power and torque. The exhaust gases (CO, NOx, SO2) and particulate matters in different engine operating regimes were analyzed using commercial diesel oil B7 (diesel oil with 7% biodiesel volume) and additions of biodiesel up to B100. The procedures used in the tests were based on the ESC (European Stationary Cycle) test of engines in chassis dynamometer. The dynamometer used was the BOSCH model FLA 203, in conjunction with a TESTO model 350 gas analyzer, a NAPRO model NA 9000 opacimeter, and a 24-channel Pro Model FUEL TECH Datalogger. The results showed that the carbon monoxide (CO) had a significant reduction of 57.22% with the engine running with B100 at 750 rpm and 84.39% at 2600 rpm in a regime of 75% of the maximum power compared to B7. Nitrogen oxide (NOx) had an increase of 145.43% with B100 at 2600 rpm. Sulfur dioxide (SO2) produced by the combustion of diesel S10, represents low values, reaching 0 ppm in any of the engine operating regimes operating with the blends. The power and torque of the engine had an increase of 2.85% and 2.81% with the B15 mixture compared to the B7 fuel, even with the B15 we can verify that the carbon monoxide (CO) had a reduction of 35.78%, nitrogen oxides (NOx) had an increase of 40.71% and opacity a reduction of 1.9%. / O presente trabalho tem como objetivo avaliar as emiss?es de gases de exaust?o e materiais particulados em um motor ciclo diesel. Foi utilizado um ve?culo caminhonete Ford, modelo F250, com motor Diesel Cummins ISB Maxi Power (EURO III), com gerenciamento eletr?nico de inje??o de combust?vel Commom Rail, buscando identificar qual mistura obt?m o melhor desempenho ambiental sem comprometer pot?ncia e torque. Foram analisados os gases de exaust?o CO, NOx, SO2 e material particulado em diferentes regimes de funcionamento do motor, utilizando o ?leo diesel comercial (B7 - ?leo diesel com 7% em volume de biodiesel) e percentuais de biodiesel at? B100. Os procedimentos utilizados nos testes foram baseados na norma ESC (European Stationary Cycle) de teste de motores em dinam?metro de chassi. O dinam?metro usado foi da marca BOSCH, modelo FLA 203, em conjunto com analisador de gases da marca TESTO, modelo 350, opac?metro da marca NAPRO, modelo NA 9000, e Datalogger da marca FUEL TECH, 24 canais, modelo Pro. Os resultados mostraram que o mon?xido de carbono (CO) teve uma redu??o de 57,22% com o motor operando com B100 em marcha lenta (750 rpm) e 84,39% na rota??o de 2600 rpm, comparado com B7. Os ?xidos de nitrog?nio (NOx) tiveram aumentos de 145,43% com B100 a 2600 rpm. O di?xido de enxofre (SO2) apresentou valores pr?ximos a 0 ppm em qualquer um dos regimes do motor. A pot?ncia e torque tiveram aumentos de 2,85% e 2,81% com B15 comparado com B7, e com B15 o mon?xido de carbono (CO) teve redu??o de 35,78%, os ?xidos de nitrog?nio (NOx) tiveram aumentos de 40,71% e a opacidade redu??o de 1,9%.
126

Improvements to the weak-post W-beam guardrail

Engstrand, Klas E 23 June 2000 (has links)
"Recent full-scale crash tests of the weak-post W-beam guardrail system have resulted in unsatisfactory collision performance as evaluated by the National Cooperative Highway Research Program (NCHRP) Report 350. Since acceptable crash test performance is required in order to use a guardrail on a Federal-Aid Highway in the United States, the poor performance of the weak-post W-beam guardrail is a significant problem to those states that use it. The goal of this project was to improve the impact performance of the weak-post W-beam guardrail system so that it satisfies the requirements of NCHRP Report 350 at test level three."
127

Improving the performance of railway track-switching through the introduction of fault tolerance

Bemment, Samuel D. January 2018 (has links)
In the future, the performance of the railway system must be improved to accommodate increasing passenger volumes and service quality demands. Track switches are a vital part of the rail infrastructure, enabling traffic to take different routes. All modern switch designs have evolved from a design first patented in 1832. However, switches present single points of failure, require frequent and costly maintenance interventions, and restrict network capacity. Fault tolerance is the practice of preventing subsystem faults propagating to whole-system failures. Existing switches are not considered fault tolerant. This thesis describes the development and potential performance of fault-tolerant railway track switching solutions. The work first presents a requirements definition and evaluation framework which can be used to select candidate designs from a range of novel switching solutions. A candidate design with the potential to exceed the performance of existing designs is selected. This design is then modelled to ascertain its practical feasibility alongside potential reliability, availability, maintainability and capacity performance. The design and construction of a laboratory scale demonstrator of the design is described. The modelling results show that the performance of the fault tolerant design may exceed that of traditional switches. Reliability and availability performance increases significantly, whilst capacity gains are present but more marginal without the associated relaxation of rules regarding junction control. However, the work also identifies significant areas of future work before such an approach could be adopted in practice.
128

eCO_URBANism Restitching Clearwater's Urban Fabric Through Transit and Nature

Uebler, Daniel P 03 November 2008 (has links)
Downtown Clearwater has grown to be disconnected from its surroundings due to an adjacent buffer area and the lack of a transit system to bring people into the city. The downtown core is also separated from its neighboring residential areas by an area of vacant land that holds in it the potential to become a gateway into the city. On a macro scale the city has grown to be separated from the Tampa Bay area due to the lack of a mass transit system. The goal of this project is to create a new "new urbanism" in which transit and natural ecology are introduced in order to link a city with its surrounding neighborhoods and with the rest of its context. The new development will provide the area with a centralized place of commerce and social interaction, while reducing the reliance on the automobile. Utilizing a light rail station and a central bus terminal, the transit oriented development or TOD will bring people into Clearwater's downtown core, bringing economic, social and environmental benefits to the area. Introduction of a natural ecosystem into the downtown fabric will attribute to the development's sustainability. The natural greenway will run through the urban fabric and also use the Pinellas Trail as an ecological corridor linking the different greenspaces of Pinellas County. New York City's High Line project provides a prime example of the introduction of a natural greenway into an urban core. The High Line brought a new life to an area that once served only the purpose of industry. Ian McHarg and Richard T. T. Forman provide examples and guidelines of how to bring the natural and built environments together as a cohesive whole. The design will look at Peter Calthorpe's ideas of transit-oriented development. Calthorpe's The Next American Metropolis will provide a set of guidelines for the design of the development. The project will create an opportunity for downtown Clearwater to be linked within its surrounding context. Transit oriented development has been proven successful throughout the country and Clearwater will benefit from its implementation.
129

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.
130

The Gold Line: Exploring the Resurgence of Public Rail Transport in Los Angeles

Dugal, Simrat L. 03 May 2010 (has links)
Mass transit in the form of light rail is, in many ways, a new and revolutionary idea for the Greater Los Angeles Area. Although mass light rail transit did exist in Los Angeles in the form of the Pacific Electric Railways red car system, an extensive network of metro rail lines has never existed in Los Angeles County since Pacific Electric was dismantled and shut down in 1950. Because of this, the popular mode of transport in LA County has traditionally been cars, and public transport has consisted mostly of bus routes. This has all changed in the last few decades. Since the 1980s, LA County has conducted several studies and, as a result of those studies, has proposed to build an extensive network of light rail lines to connect the county. In more recent years, many of these project plans have been approved, and the MTA has overseen the construction and functioning of new railway lines that are connecting far-flung regions of LA County with Union Station in downtown LA. Currently, the MTA operates 5 light rail lines within LA county-the Blue Line, the Red Line, the Purple Line, the Green Line and the Gold Line-that extend north, south and east of downtown LA. Each of these lines has been functional for a varying amount of time, but current weekday ridership on this system of lines has crossed the 280,000 mark as off September 2009.

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