published_or_final_version / Urban Planning / Master / Master of Science in Urban Planning

This dissertation deals with the development of a model-based diagnostic system for air brake systems that are widely used in commercial vehicles, such as trucks, tractor-trailers, buses, etc. The performance of these brake systems is sensitive to maintenance and hence they require frequent inspections. Current inspection techniques require an inspector to go underneath a vehicle to check the brake system for possible faults, such as leaks, worn brake pads, out-of-adjustment of push rods, etc. Such inspections are time consuming, labor intensive and difficult to perform on vehicles with a low ground clearance. In this context, the development of an onboard/ handheld diagnostic tool for air brakes would be of significant value. Such a tool would automate the brake inspection process, thereby reducing the inspection time and improving the safety of operation of commercial vehicles. In this dissertation, diagnostic schemes are developed to automatically detect two important and prevalent faults that can occur in air brake systems – leaks and out-of-adjustment of push rods. These diagnostic schemes are developed based on a nonlinear model for the pneumatic subsystem of the air brake system that correlates the pressure transients in the brake chamber with the supply pressure to the treadle valve and the displacement of the treadle valve plunger. These diagnostic schemes have been corroborated with data obtained from the experimental facility at Texas A&M University and the results are presented. The response of the pneumatic subsystem of the air brake system is such that it can be classified as what is known as a “Sequential Hybrid System”. In this dissertation, the term “hybrid systems” is used to denote those systems whose mathematical representation involves a finite set of governing ordinary differential equations corresponding to a finite set of modes of operation. The problem of estimating the push rod stroke is posed as a parameter estimation problem and a transition detection problem involving the hybrid model of the pneumatic subsystem of the air brake system. Also, parameter estimation schemes for a class of sequential hybrid systems are developed. The efficacy of these schemes is illustrated with some examples.

The purpose of this research is to provide a theoretical framework for future commercial vehicle user-charging using real-time vehicle weight and configuration information collected using weigh-in-motion (WIM) systems. This work provides an extensive review of both mechanisms and technologies employed for commercial and passenger vehicle user-charging worldwide. Existing commercial vehicle-user charging structures use only broad vehicle classifications to distinguish between vehicles for the pricing of user-fees. The methodology proposed in this study employs highway cost allocation methods for development of an “Axle-Load” toll structure. A theoretical case study, based on information from Texas State Highway 130, is performed to explore the equity improvements that could be achieved through implementation of this proposed structure. Some sensitivity analysis is also performed to examine the potential revenue impacts due to uncertainties in different data inputs under existing and proposed structures. / text

Thesis (M.S.)--Brigham Young University. Dept. of Civil and Environmental Engineering, 2006. / Includes bibliographical references (p. 125-129).

Thesis (M.S.)--University of California, Davis, 2004. / Text document in PDF format. Title from PDF title page (viewed on September 15, 2009). "Received by ITS-Davis: June 2004"--Publication detail webpage. Includes bibliographical references (p. 115-122 and p. 175).

Made available in DSpace on 2014-06-11T19:35:40Z (GMT). No. of bitstreams: 0 Previous issue date: 2009-03-06Bitstream added on 2014-06-13T20:08:34Z : No. of bitstreams: 1 kubo_pyy_dr_guara.pdf: 854634 bytes, checksum: c91e3063ee56f2acff6f33e070c95dd7 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / O objetivo principal desta Tese é analisar prospectivamente as tendências sobre as estratégias mundiais de desenvolvimento dos veículos comerciais frente aos cenários nacional e internacional atuais. Para tanto, foi realizada uma pesquisa usando o método Delphi, que consiste em regular, sistematicamente, a apresentação de perguntas acerca de um determinado problema a um grupo de especialistas. Para um levantamento mais abrangente optou-se por aplicar os questionários a três grupos distintos: Acadêmicos, Executivos das montadoras de veículos comerciais e Executivos das indústrias de autopeças. É possível concluir, após a análise dos resultados, que o Brasil possui atualmente uma posição confortável na comercialização de caminhões e ônibus, além de certa autonomia no desenvolvimento desses veículos em relação às empresas matrizes. Adicionalmente destaca-se que poucos foram os argumentos que justificariam mudanças desse cenário até o ano de 2018, porém há claras deficiências – como ausência de profissionais (engenheiros) qualificados no mercado e necessidade de maior intercâmbio entre empresas e Universidades - que devem ser analisadas e superadas de modo a garantir ao Brasil a sustentabilidade no desenvolvimento deste tipo de produto. / The main objective of this Thesis is to present a prospective analysis about the tendencies of the world wide strategies of commercial vehicles’ development, in relation to the current local and international scenery. It has been done a research by using the Delphi method, which consists to regulate, systematically, the presentation of questions about a specific problem to a group of specialists. In order to guarantee more representative data, it has been adopted three distinct groups: Academics, OEMs Managers and OEM´s suppliers Managers. It is noticeable, after the data’s analysis, that Brazil has nowadays a comfortable status on the commercial vehicles’ market and also a good autonomy on product development. The specialists presented few arguments that could justify the modification of this scenery up to 2018, although there are clear evidences – like lack of qualified engineers on Brazilian market and the necessity of a better exchange of knowledge between the OEMs and Universities – that must be analyzed and suppressed, in order to guarantee the Brazilian product development sustainability in this segment.

AFRIKAANS: 'n Basiese toets spesifikasie, vir die toets van bak-kappies van ligte kommersieële voertuie word voorgestel. Die toets spesifikasie is 'n eerste stap na die kwalifikasie van die sterkte van bakkie-kappies tydens ongelukke. Die toets is ontwerp spesifiek met die omrol scenario in gedagte. Verskillende toets metodes is geëvalueer vir toepaslikheid, gemak van implementasie en finansiele beperkings gedurende die navorsingsfase. Die massa-, en geometriese-eienskappe van drie verskillende I ton bakkies is eksperimenteel gevind om as basis vir energie berekeninge te dien. Die energie wat elkeen van hierdie voertuie besit net voor dit omrol is bereken en as voorlopige toets kriterium gebruik. 'n Pendulum impak toets-prosedure sowel as 'n Eindige Element Analise (EEA) prosedure is in die voorlopige toets kriterium ingesluit. Die voorlopige toets kriterium is gedurende 'n volskaal impak toets op 'n bakkie-kappie toegepas. 'n Detail eindige element analise van die kappie struktuur is ook volgens die kriterium gedoen. Daar is bewys dat beide hierdie metodes lewensvatbaar is vir implementasie en dat dit gebruik kan word vir die verifieëring van die sterkte van bakkie-kappies. Die resultate gevind gedurende hierdie toetse is gebruik om die voorlopige toets kriterium aan te pas om 'n basiese toets-spesifikasie te verkry waarmee bakkie-kappies deur toets owerhede geevalueer kan word. ENGLISH: In this thesis a basic test specification for a canopy that covers the load¬bed-area of a light commercial vehicle (LCY) is proposed. The test specification is a first step towards the qualification of the strength of a canopy during an accident. The test is designed specifically with the rollover scenario in mind. Different testing methods were evaluated for applicability, ease of use and financial constraints during the research phase. The mass and geometric characteristics of three different 1 ton LCY's were found experimentally in order to set a basis for the energy calculations. The energy each of these vehicles possesses just prior to roll over was calculated and used to create preliminary testing criteria. A pendulum impact testing procedure as well as a Finite Element Analysis (FEA) procedure were incorporated into the preliminary testing criteria. The preliminary testing criteria were applied during a full scale pendulum impact test on a canopy and were also applied during a detailed finite element analysis of the canopy structure. It was shown that both of these test methods are viable and that they can be used as a canopy strength qualifying means. Finally the results found during the tests were used to adjust the preliminary testing criteria to form a basic test specification that can be used by testing and qualification facilities. / Dissertation (M Eng (Mechanical Engineering))--University of Pretoria, 2006. / Mechanical and Aeronautical Engineering / unrestricted

A human factors experiment was conducted to assess the intelligibility of synthesized speech under a variety of noise conditions for both hearing-impaired and normal-hearing subjects. Modified Rhyme Test stimuli were used to determine intelligibility in four speech-to-noise (S/N) ratios (0, 5, 10, and 15 dB), and three noise types, consisting of flat-by-octaves (pink) noise, interior noise of a currently produced heavy truck, and truck cab noise with added background speech. A quiet condition was also investigated. During recording of the truck noise for the experiment, in-cab noise measurements were obtained. According to OSHA standards, these data indicated that drivers of the sampled trucks have a minimal risk for noise-induced hearing loss due to in-cab noise exposure when driving at freeway speeds because noise levels were below 80 dBA. In the intelligibility experiment, subjects with hearing loss had significantly lower intelligibility than normal-hearing subjects, both in quiet and in noise, but no interaction with noise type or S/N ratio was found. Intelligibility was significantly lower for the noise with background speech than the other noises, but the truck noise produced intelligibility equal to the pink noise. An analytical prediction of intelligibility using Articulation Index calculations exhibited a high positive correlation with the empirically obtained intelligibility data for both groups of subjects. / Master of Science

O presente trabalho apresenta uma proposta de desenvolvimento e aplicação de um programa de simulação computacional usando o software MatLab/Simulink 6.0 como ferramenta de Engenharia Automotiva, aplicando-a para o estudo do desempenho de veículos comerciais rodoviários (caminhonetes, caminhões e ônibus) em movimentos acelerados e em regime permanente. O programa de simulação considera o motor mapeado em torque e consumo específico e o sistema de transmissão do eixo do motor às rodas motrizes e se conecta a outro programa de simulação existente e desenvolvido no Laboratório de Computação Veicular da EESC-USP. Para as simulações foram utilizados os dados de um veículo comercial característico submetido a várias situações de movimento acelerado em pista horizontal e inclinada, quando foram obtidos dados importantes como consumo médio e instantâneo do veículo para cada um dos cenários previstos. Outros dados como os espaços percorridos, as velocidades, as acelerações, as rotações do eixo do motor, o escorregamento parcial dos pneumáticos e outros são apresentados neste trabalho. Adicionalmente, o programa de simulação mostra potencial de uso nas fases de projeto, desenvolvimento e otimização dos veículos comerciais, podendo reduzir custos com a diminuição dos prazos e testes necessários para a avaliação do desempenho do veículo em pista de provas. Apresenta também potencial de aplicação na melhor especificação do veículo a ser comprado pelo frotista considerando as condições específicas do seu uso. / This work presents a development and application proposal of a simulation program using the software Matlab/Simulink 6.0 as an Automotive Enginnering tool, applying it for the study of the commercial vehicles performance in accelerated and uniform movement. The simulation program considers the engine maps of specific fuel consumption and torque curves and also the transmission system between the engine and the tractive wheels. The simulation program connects itself with another simulation program developed in the EESC-USP Vehicle Computation Laboratory. For the simulations were used the data of a characteristic commercial vehicle submited to various situations on horizontal and inclinated roads, when were taken relevant data like average and instant fuel consumption for each predicted scene. This work also presents vehicle operational data as engine speed, covered spaces, longitudinal velocities and accelerations, adherence and relative slip of the wheels and others. The simulation program shows a hugh potential use in the optimization, development and project phases of commercial vehicles, allowing saving of time and financial resources. The simulation program shows also a potential application in the best vehicle specification to be bought by the client considering the specific conditions of its use.

A evolução dos sistemas de transporte no modal rodoviário tem criado novas demandas operacionais devido à crescente concorrência e aumento da pressão para a redução de custos. Em face dessas novas demandas, muitas delas advindas da globalização, geraram uma mudança no perfil da frota de veículos comerciais pesados no mercado brasileiro. Frotas que anteriormente eram compostas por veículos comerciais pesados 4x2 (4 pontos de apoio no solo com tração em 2 pontos) operando com carretas de três eixos com capacidade de transporte de 45 toneladas, passaram a ser gradativamente substituídas por aquelas compostas por veículos comerciais pesados 6x2 (6 pontos de apoio no solo com tração em 2 pontos) com carretas do tipo bi-trem e rodo-trem com capacidade de transporte de 57 e 74 toneladas respectivamente. Esta mudança foi acompanhada pelo aumento da pressão do custo de aquisição dos veículos comerciais pesados, com isso, verificou-se que os principais frotistas brasileiros passaram a adaptar eixos de apoio nos veículos 4x2, aumentando assim as solicitações mecânicas impostas ao sistema de embreagem. Neste trabalho desenvolve-se, portanto, um estudo sobre as falhas ocorridas no sistema de acionamento de embreagem por cilindro escravo concêntrico no mercado brasileiro, avaliando-se a seleção de materiais empregados na construção do sistema através de ensaios químico-laboratoriais e testes de funcionalidade através de ensaios em condições reais de operação com veículos comerciais pesados devidamente instrumentados, mantendo o foco nos novos parâmetros operacionais impostos pelo novo perfil da composição tratora. Como resultado, apontam-se duas alternativas para a solução das falhas encontradas no mercado brasileiro: 1. Proposição de nova solução técnica construtiva para o sistema de acionamento da embreagem a fim de aumentar a robustez do componente de maior suscetibilidade às falhas. 2. Proposição de um modelo matemático para a predição do intervalo mínimo de manutenção para o sistema de acionamento da embreagem por cilindro escravo concêntrico. / The evolution of highway transportation of goods in the brazilian market has created new operation requirements due to the increased competition allied to the cost reduction demands. This new demands, most of them coming from globalization, have generated a significant change on the profile of heavy commercial vehicles. Fleets that were mainly composed of 4x2 tractors coupled to three wheeled semi-trailers with towing capacity of 45 tons, were in small steps exchanged by new compositions of tractors 6x2 coupled to bi-trains and road-trains with total towing capacity of 57 and 74 tons, respectively. This change have been followed by the new purchasing demands from fleet owners by lowering acquisition costs of new heavy commercial vehicles, as a consequence, most of 4x2 trucks have been adapted with tag-axles in order to increase towing capacity, which means increasing the stresses over the clutch system. On this research, a case study is developed about failures on clutch systems actuators by the concentric slave cylinder concept in the brazilian market. The research is developed by the evaluation of types of materials selected to the system components through chemical test and functionality tests carried on actual operation conditions on instrumented vehicles, keeping always the focus on the new operational demands imposed by the new profile of vehicle compositions (bi-trains and road-trains). As a final result, two alternatives are appointed to solve the failures in the brazilian market: 1. By the determination of the most failure susceptible component, it is possible to propose a mathematical and theoretical model to determine the minimum maintenance interval to the clutch actuation system by concentric slave cylinder concept. 2. Proposition of a new technical construction to the system in order to increase the robustness of the component most susceptible to the failures.