An ongoing experiment is described to demonstrate the principle of multi-pulse laser wakefield acceleration, in which a plasma wakefield is resonantly excited by a train of laser pulses, spaced by the plasma wavelength. Particle-in-cell simulations of the initial single-pulse experimental setup are presented, in order to calculate the expected signal. Preliminary results are presented and future plans, based on work done so far, are discussed. Part of this work involves the implementation of a single-shot wakefield diagnostic - frequency-domain holography, which records the phase shift caused by passage of a probe pulse through the plasma. This implementation is described in detail, along with the associated analysis procedure. Practical difficulties encountered while implementing the diagnostic are discussed, along with possible ways of mitigating them in the future. A method is presented by which the noise level in the resulting phase measurements can be predicted, much more accurately than any previously published method for this technique. Methods of generating pulse trains for use in future multi-pulse laser wakefield acceleration experiments are presented. These include techniques proposed for use in this demonstration experiment, as well as one intended for use in a dedicated high-efficiency, high repetition-rate, multi-pulse driver laser. This last method, based on programmable pulse shaping using a spatial light modulator, requires a suitable mask to be computed based on the parameters of the required pulse train; an algorithm is described to perform this computation.

Florida, the fourth largest and sunshine state, is growing at the rate of 800 new residents daily.!! By the year 2000 the population is estimated to be 16 Million, and the annual tourists at 80 Million, generating 40 Million trips. The proposed High Speed Rail will connect Miami and West Palm Beach to Orlando and Tampa. This 325-mile corridor represents 70 % of all the "Socio-Economic Resources" of the whole of Florida and the trend will continue well into the next century. The Miami-Orlando ride will reduce to 2 hours speeding at up to 150 mph. It will be operational by 1995 and the system is estimated to cost 4.6 Billion Dollars. One of the major problems encountered by the new High Speed Rail (HSR) is the "RIDERSHIP FORECASTING," In the United States there is a lack of current information about the Total Volume of Intercity Trips and the Specific Characteristics of the Trips that determines a willingness to use HSR. The Quality, Comprehensiveness, and Acceptability, by the forecasts must be sufficient to generate Public Support, Confidence, and Response for the Implementation of HSR. The THESIS discusses the various Ridership Forecasting Techniques and chooses the “Most Suitable Model” applicable to conditions in South and Central Florida. A “Model Choice Based Model” is selected called, “THE LOGIT FUNCTION”, which takes into account, the Floridian Choice of available Travel Modes, and the Factors Affecting the Manner of the “Decision making Process”, in Favour of a Particular Mode. Evaluating Business and Non-Business Travel for the Internal Trips, (including the Induced Demand and the Short Trips) and the External Trips. The External and Short Trips were Not considered by Previous Studies. The standard guidelines for “Revenue and Ridership Forecasting,” by High Speed Rail Association are closely followed in this Study. Due consideration is also given to Socio-Economic data involving population, wealth, average per capita income, number of families, size of labor force, number of hotel / motel rooms and college enrollment. A Survey was carried out, to collect the data and to test the Sensitivity, under given set of conditions and scenarios. The studies conclude that HSR is a Feasible Project and by the year 2000, the Ridership will be 3.8 Million Annual Trips. The future studies will continue to improve the results, as an individual’s attitude and response towards HSR Travel becomes better known and recorded in Florida

Este trabalho utiliza uma metodologia simplificada de análise dinâmica para o estudo das vibrações em pontes ferroviárias, produzidas pela passagem de um trem de alta velocidade, associadas à presença de irregularidades nos trilhos. Iniciou-se o estudo a partir de um modelo do veículo composto por quinze graus de liberdade, referentes aos deslocamentos verticais e horizontais transversais, e rotações em torno dos eixos longitudinal, transversal e vertical. Os modelos dinâmicos do trem e da ponte foram tratados de forma desacoplada, sendo conectados pelas forças de interação trem-ponte. Desta forma, foram calculados os carregamentos provenientes da modelação dinâmica do trem, adotando-se inicialmente a hipótese de tabuleiro rígido e indeslocável e, ainda, considerando-se a presença de irregularidades geométricas nos trilhos no plano vertical. Neste trabalho, foi considerado um estudo de caso utilizando-se o modelo veicular Alfa Pendular, avaliando-se a resposta dinâmica do trem e da estrutura, considerando o efeito das irregularidades geométricas nos trilhos, bem como a presença do lastro. As forças de interação obtidas da modelagem do veículo foram aplicadas em um modelo estrutural de alta hierarquia da ponte, dividido em elementos finitos de casca, sendo que em cada nó do modelo da ponte foram especificados os esforços obtidos da análise dinâmica do veículo. Para representar a passagem do comboio sobre a ponte, foram utilizadas funções que descrevem as forças de interação trem-ponte em cada nó do modelo da ponte, em cada intervalo de tempo, até que todo o trem tenha percorrido o comprimento da ponte. A consideração de tabuleiro rígido indeslocável foi corrigida por meio de um processo iterativo, de forma que os deslocamentos do tabuleiro obtidos para a primeira determinação dos esforços de interação foram somados às irregularidades do trilho (excitação de suporte aplicada nas rodas do trem). Com isso, foi possível identificar a resposta dinâmica proveniente da carga em movimento e das irregularidades geométricas nos trilhos, avaliando o conforto dos passageiros no interior do vagão. Por fim, realizou-se uma análise de distribuição estatística para avaliar a probabilidade de se ultrapassar os limites estabelecidos pelo Eurocode. / This thesis resorts to a simplified methodology of dynamic analysis for the study of vibrations in railway bridges, produced by the passage of a high speed train, associated to the presence of irregularities in the rails. The study started from a vehicle model composed of fifteen degrees of freedom, namely, vertical and lateral displacements, and rotations about the longitudinal, lateral and vertical axes. The dynamic models of the train and the bridge were treated as uncoupled, yet being bound by the interaction train-bridge forces. Thus, the loads from the dynamic model of the train were calculated, adopting initially the hypothesis of rigid and fixed deck and also, considering the presence of geometric irregularities in the vertical track plane. In this work, we considered a case study using the Alfa Pendular vehicle model, evaluating the dynamic response of the train and the structure, considering the effect of the geometric irregularities at the tracks, as well as the presence of the ballast. The interaction forces obtained from the model of the vehicle were applied in a high hierarchy structural model of the bridge, divided into shell finite elements, specifying the forces obtained from the dynamic analysis of the vehicle at each node of the bridge model. To represent the train passage on the bridge, functions were used to describe the bridge-train interaction forces at each node of the bridge model at each time interval, until the entire train had travelled the bridge length. The consideration of rigid and fixed deck was corrected by means of an iterative process, so that the deck displacements obtained for a first determination of the interaction forces were added to the rail irregularities (excitation applied to the train wheels). Thus, it was possible to identify the dynamic response caused both by the moving loading and the geometrical irregularities of the tracks, evaluating the comfort of the passengers inside the wagon. Finally, a reliability study was carried out to evaluate the probability of exceeding the limits established by Eurocode.

Orientador: Fernando Antonio Campos Gomide / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Eletrica e de Computação / Made available in DSpace on 2018-08-10T00:48:57Z (GMT). No. of bitstreams: 1 Tazoniero_Alexandre_M.pdf: 2202986 bytes, checksum: eac2bab1d27c5baaf56ef296663e1cef (MD5) Previous issue date: 2007 / Resumo: O transporte ferroviário tem grande participação no transporte de cargas e passageiros em todo o mundo. No Brasil a malha ferroviária sofreu um processo de abandono e deterioração no período de 1960 a 1990. A partir de 1990 a privatização da rede ferroviária nacional iniciou uma retomada de investimentos e nos últimos anos à demanda por transporte ferroviário vem crescendo significativamente. É necessário, então, que os recursos da ferrovia sejam utilizados de maneira eficiente para atender a crescente demanda, o que exige planejamento estratégico, táctico e operacional. No nível operacional uma das principais etapas e também umas das mais carentes de ferramentas computacionais é o Planejamento de Circulação de trens. O processo operacional de uma ferrovia é dinâmico, sujeito a inúmeras interferências imprevisíveis e uma ferramenta computacional para o apoio ao planejamento de circulação de trens deve fornecer soluções com tempo de processamento compatível com essa realidade. Este trabalho propõe algoritmos para o planejamento de circulação de trens em tempo real, utilizando metodologias de inteligência computacional e conjuntos nebulosos. Um algoritmo objetiva decidir localmente a preferência entre trens concorrendo pelo uso de um segmento de linha singela de modo a seguir uma referência de percurso fornecida por algum algoritmo de otimização ou por um especialista. Outro algoritmo decide, além da preferência entre trens, a velocidade de percurso dos trens para mantê-los o mais próximo possível de suas referências. O terceiro algoritmo usa elementos de busca em árvore para obter uma solução para o planejamento de circulação de trens. É feito um estudo comparativo dos algoritmos aqui propostos e de algoritmos existentes na literatura. O estudo comparativo é feito a pm1ir de instâncias pequenas de problema de planejamento de circulação e uma instância que considera dados reais de uma ferrovia brasileira. Os resultados mostram que os algoritmos propostos obtêm soluções próximas às ótimas para as instâncias pequenas e soluções satisfatórias para o caso real / Abstract: Railways plays a major role in freight and passenger transportation in the whole world. The Brazilian railway system has suffered a process of abandon and deterioration from 1960 to 1990. Since 1990 the privatization of the national railways brought new investments and in the last years the demand for railway transportation has increased significantly. Railway resources must be efficiently managed to match the increasingly transportation demand. This requires efficient strategic, tactical and operational planning. One of the main tasks at the operational planning level concerns train circulation and associated tools. Railway operation is a very dynamic process because trains are subject to many unexpected interferences. Computational tools to help trains circulation planning must provide solutions in a time range consistent with real-time needs. This work suggests algorithms for real-time train movement planning, using computational intelligence and fuzzy set theory methodology. One of the algorithms decides the preference between trains competing for a single line track at the same moment. The aim is to drive train circulation as dose as possible to reference trajectories supplied by human experts, global optimization algorithms or both. Other algorithm decides preference between trains and chose the velocity with which trains must travel to remain as dose as possible to its references. The third algorithm uses depth search algorithm to obtain a solution for train circulation problems. A comparative study considering the algorithms proposed herein and algorithms suggested in the literature. The comparative study is done using small railway system instances. Data of a major Brazilian railway is adopted to illustrate how the algorithms behave to solve larger instances. Results show that the algorithms here proposed obtain near optimal solutions for small instances and satisfactory solutions for the real case / Mestrado / Automação / Mestre em Engenharia Elétrica

Orientador: Luis Eduardo Evangelista de Araujo / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Fisica Gleb Wataghin / Made available in DSpace on 2018-08-14T22:09:31Z (GMT). No. of bitstreams: 1 Soares_AntonioAugusto_D.pdf: 11187832 bytes, checksum: 3ffb3d078fef8dd053b760fc0342ec6f (MD5) Previous issue date: 2009 / Resumo: Nesta tese apresentamos um estudo teórico da interação coerente entre trens de pulsos ultracurtos e sistemas atômicos simples de dois e três níveis, este último na configuração L. Primeiramente avaliamos a situação em que um trem de pulsos ultracurtos não só sonda um sistema de três níveis na configuração L, mas também leva o átomo à configuração do átomo vestido. Nessas condições estudamos o efeito do acúmulo coerente de excitação na transparência eletromagneticamente induzida (EIT) experimentada pelo trem de pulsos ultra-curtos. Mostramos que os parâmetros do trem de pulsos ( área do pulso, diferença de fase entre pulsos consecutivos e período de repetiçãco dos pulsos) determinam a dinâmica da formação da EIT. Em seguida estudamos os efeitos da propagação do trem de pulsos ultracurtos através de um meio atômico estendido, constituído por sistemas de dois e três níveis na configuraçãco L. Mostramos que no caso em que o meio é constituído por sistemas de dois níveis a frequência central dos pulsos é rapidamente removida devido à propagação, prejudicando o efeito de acúmulo coerente. Já para o meio constituído por sistemas de três níveis o efeito acumulativo é observado e coerência é transferida ao meio, levando a uma sobreposição linear entre os níveis fundamentais, sobreposição esta que está associada à formação da EIT. Após um número suficientemente grande de pulsos o meio se torna transparente aos pulsos subsequentes que se propagam sem sofrer alterações em seu perfil temporal e espectral. Outra situação que estudamos nesta tese é aquela onde o sistema atômico é excitado por um campo contínuo monocromático levando o átomo à configuração do "átomo vestido". Este sistema é, então, investigado por um trem de pulsos ultracurtos. Neste caso mostramos que a utilização do trem de pulsos ultracurtos permite a realização de espectroscopia de alta resolução dos estados atômicos vestidos induzidos pelo campo contínuo monocromático / Abstract: In this thesis we present a theoretical study about the coherent interaction between a train of ultrashort pulses with two- and three-level atomic systems, this last in the L configu-ration. Firstly, we investigated the situation at which a train of ultrashort pulses not only probes the three-level system in the L configuration, but also drives the atom to its dressed configura-tion. Under these conditions, we studied the effects of the coherent accumulation of excitation on the electromagnetically induced transparency (EIT) of the train of ultrashort pulses. We showed that the pulse train parameters (area, repetition period, and phase between successive pulses) play a significant role in establishing EIT. Then, we study the effects of propagation through an extended sample of two- and three-level atoms. We showed that in the two-level case, absorption of the pulse¿s resonant frequency by the atoms quickly compromises the accumulation of excitation. In the three-level case, the accumulative effect occurs, and the pulse train transfers coherence between the two lower states of the atoms, driving population into a dark superposition state. Such a superposition is related to the EIT formation and after a large enough number of pulses, the medium becomes transparent to the driving pulses. Later pulses in the train propagate through the atomic medium with both their amplitude and temporal profile preserved. Another configuration that we investigated in this thesis is that at which the atomic system is excited by a monochromatic cw laser that drives the atom to its dressed configuration. Such a system is then probed by an ultrashort pulse train. In this case, we showed that an ultrashort pulse train can be used to perform high-resolution spectroscopy of dressed atomic states / Doutorado / Física Atômica e Molecular / Doutor em Ciências

Orientador: Fausto Rodrigues Filho / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica / Made available in DSpace on 2018-07-25T03:07:16Z (GMT). No. of bitstreams: 1 Martins_SergioRoberto_M.pdf: 8034823 bytes, checksum: 3e3436c2fbc1bce2cd2db72d860250ca (MD5) Previous issue date: 1999 / Resumo: O presente trabalho apresenta um programa computacional para a simulação da frenagem de trem unitário de carga, que são trens compostos por uma grande quantidade de vagões iguais. É feita uma análise das variáveis envolvidas no processo de frenagem, com o objetivo de padronização na determinação destes valores para que haja consistência nos resultados das simulações, permitindo análise comparativa. Finalizando são feitos diversos lotes de simulações, compatíveis com situações reais das ferrovias brasileiras, e uma análise comparativa dos resultados para avaliar a influência das variáveis no processo de frenagem do trem / Abstract: This study presents a computer simulation software to analyse the unit freight train braking process. These are long trains having a great number of equal freight cars. It is made an analysis of the variables involved on the braking process with the purpose of standardization of these values to get consistency on the simulationresults to allow comparative analisis. Endly are made several simulations, according to real situations found in the Brazilian railways and a comparative analysis of the results to avaliate the influence of the variables in the train braking process / Mestrado / Mecanica dos Sólidos e Projeto Mecanico / Mestre em Engenharia Mecânica

Denna rapporten studerar effekterna i det svenska järnvägsnätet och kvaliten på de estimerade ankomsttider för tågen. Effekterna som studeras i rapporten är resultatet av hur kvaliten på ankomsttideren ändras när en positioneringsapparat introduceras i järnvägstrafiken. Rapporten studerar också hur kvaliten på uppskattningen av ankomsttidernas ändras då man reducerar antalet driftledningscentraler och centraliserar järnvägsorganisationen. Rapporten fortsätter med att rangordna dessa olika metoder och utreda vilken av de två metoderna som har störst inverkan och som är den mest fördelaktiga metoden. Ett försök görs också att sätta ett värde på hur mycket bättre varje metod, och olika kombinationer av metoderna, är i förhållande till varandra. / Denna rapporten studerar effekterna i det svenska järnvägsnätet och kvaliten på de estimerade ankomsttider för tågen. Effekterna som studeras i rapporten är resultatet av hur kvaliten på ankomsttideren ändras när en positioneringsapparat introduceras i järnvägstrafiken. Rapporten studerar också hur kvaliten på uppskattningen av ankomsttidernas ändras då man reducerar antalet driftledningscentraler och centraliserar järnvägsorganisationen. Rapporten fortsätter med att rangordna dessa olika metoder och utreda vilken av de två metoderna som har störst inverkan och som är den mest fördelaktiga metoden. Ett försök görs också att sätta ett värde på hur mycket bättre varje metod, och olika kombinationer av metoderna, är i förhållande till varandra. / Email: jo.persson@gmail.com

M.Ing. / The increase in awareness of the environmental problems resulting from emissions released from vehicles have forced governments and car manufactures to invest more time in to the designing a vehicle that is an alternative to petrol driven vehicles. This dissertation aims to introduce a control strategy to manage the flow of energy of different power sources that may be found on a vehicle. Hybrid vehicles are a possible solution to reducing carbon emissions that play a part in global warming. In this dissertation, di erent hybrid vehicles are de ned and their components discussed in detail. The possibility of more than one energy source to power the vehicle introduces more exibility in terms of the drivetrain but this increases the complexity of the energy control management. The goal is to optimize the energy control management to reduce fuel consumption and therefore reduce emissions. Operating procedures for the various hybrid con gurations are discussed. Simulations of the Energy Management System of the hybrid electric vehicle are used to develop the control optimization algorithm. Various control optimization procedures are discussed. Satisfactory results from the simulations allow the implementation of the hybrid onto a platform entered into the South African Solar Challenge 2010, which covered a distance of 4000 km. The Energy Management system selected for the parallel hybrid electric vehicle demonstrated fuel savings, which meant a reduction in emissions, which is the goal of any hybrid vehicle. Further investigations include more intelligent controllers to adjust the parameters of the energy management controller to allow for adaptation to various driving conditions, e.g. urban and motorway driving.

The following dissertation is located in South Africa, Pretoria. The aim is to define the Threshold of entry from the South of Pretoria, passing the University of South Africa and via Elandspoort Road and Mears Street. An Urban Design and Centre for Media + Image form the final resolution for the proposal. Education and Display are explored in creating a facility for the University of South Africa and a public and visual venue for Pretoria. Connection and Communication are the theoretical concepts carried through into the design. This is done in order to fully integrate design within a context both locally and internationally. Visual interaction with the building in the following design is a major factor. This is due to the dynamics surrounding the site and already existing movement channels and patterns creating an Urban Environment. The work of Bill Hillier has been consulted in relation to Architecture and Movement. The design approach is one of aknowleding our place in time. This is reflected in the programme for the facility and in the environment and technologies incorporated. Tilt-Up Construction, Post-Tensioned Slabs and Steel Construction are the main building methods. Steel, Glass and Concrete make up the material palette in conjunction with technological advances such as nanotechnology and smart surfaces. Steel and Glass Louvre Systems with Nanotechnology enable Large Screen Display on external Surfaces of the Facility. Copyright 2006, University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria. Please cite as follows: Bevan, B 2006, Centre for Media + Image, MArch(Prof) dissertation, University of Pretoria, Pretoria, viewed yymmdd < http://upetd.up.ac.za/thesis/available/etd-10122006-121826/ > / Dissertation (MArch (Prof))--University of Pretoria, 2007. / Architecture / unrestricted

In the stochastic modeling of neurons, the first passage time problem arises as a natural object of study when considering the inter spike interval distribution. In this report, we study some aspects of this problem as it arises in the context of neuroscience. In the first chapter we describe the basic neurophysiology required to model the neuron. In the second, we study the Poisson model, Stein’s model, and some diffusion models, calculating or indicating methods to compute the density of the first passage time random variable or its moments. In the third and fourth chapters, we study the Fokker-Planck equation, and use it to compute the first passage time in the discrete and continuous time random walk cases. In the final chapter, we study sequences of neurons and the change in the density of the waiting time distributions, and hence in the inter spike intervals, as the output spike train from one neuron is considered as the input in the subsequent neuron.