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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.
161

Implicações da estratégia modular no processo de capacitação e na transferência de atividades de desenvolvimento de produto entre os fornecedores de nível 1 e 2 da cadeia automotiva. / The modular strategy implications in the capability process and in the transfer of product development activities among the first and second tier suppliers of the automotive chain.

Prieto, Evandro 14 August 2007 (has links)
O desenvolvimento de novos produtos no contexto da estratégia modular implica em uma redistribuição das atividades inerentes a este processo, devido à decomposição das tarefas de desenvolvimento do projeto entre as montadoras e seus fornecedores. Neste contexto, o presente trabalho investiga as implicações da estratégia modular no processo de capacitação e na transferência de atividades de Desenvolvimento de Produto (DP) entre os fornecedores de nível 1 e 2 da cadeia automotiva de suprimentos. A pesquisa se desenvolve por meio da abordagem de estudo de casos múltiplos, realizado em quatro empresas do setor automotivo. O modelo de progressividade de competências modulares foi aplicado nas empresas selecionadas e permitiu identificar graus distintos de maturidade modular. O grau de maturidade nas competências modulares apresentadas nestas empresas determina, ao mesmo tempo, o processo de transferência de atividades e a intensidade do envolvimento nas práticas de desenvolvimento de produtos com seus clientes. A pesquisa constatou que quanto maior o grau de maturidade modular, maior a tendência dos fornecedores da cadeia automotiva de participar em projetos de DP das montadoras em sistema de parceria e mediante investimentos de risco. A pesquisa constatou que quanto maior o grau de maturidade modular, maior a tendência dos fornecedores da cadeia automotiva de participar em projetos de DP das montadoras em sistema de parceria e mediante o compartilhamento do risco nos investimentos. / The new product development in the context of the modular strategy implies in a redistribution of the inherent activities of this process, being based on the decomposition and division of the project tasks developed among the assemblers and theirs suppliers. In accordance to this context, the present work investigate the implications of the modular strategy in the transference processes related to the Product Development (PD) activities that happens between the 1rst and 2nd tier of the automotive chain. The research is developed by the approach of multiple case studies, carried through in four companies of the automotive sector. The maturity level of modular competences on these suppliers in such a way determines, at the same time, the processes of transference of activities and the supplier\'s involvement in the product development activities. In accordance with the analysis of this work was possible identify that the modular strategy is promoting the improvement in the relationship among the OEM (Original Equipment Manufacturers) and the suppliers positioned in the modular stages of development and maturity. The research identified that the modular maturity level implies in the involvement level in PD projects of the OEM with the system of partnership and with the sharing of investment risks.
162

Buzz or Beep? How Mode of Alert Influences Driver Takeover Following Automation Failure

January 2018 (has links)
abstract: Highly automated vehicles require drivers to remain aware enough to takeover during critical events. Driver distraction is a key factor that prevents drivers from reacting adequately, and thus there is need for an alert to help drivers regain situational awareness and be able to act quickly and successfully should a critical event arise. This study examines two aspects of alerts that could help facilitate driver takeover: mode (auditory and tactile) and direction (towards and away). Auditory alerts appear to be somewhat more effective than tactile alerts, though both modes produce significantly faster reaction times than no alert. Alerts moving towards the driver also appear to be more effective than alerts moving away from the driver. Future research should examine how multimodal alerts differ from single mode, and see if higher fidelity alerts influence takeover times. / Dissertation/Thesis / Masters Thesis Human Systems Engineering 2018
163

Dimensionamento e avaliação do ciclo de refrigeração de sistema de climatização automotivo. / Sizing and evaluation of an automotive climate system refrigeration cycle.

Santos, Eduardo Oliveira dos 02 September 2005 (has links)
O ser humano consome grandes quantidades de energia para satisfazer as suas necessidades de conforto. Dentro do setor automotivo, depois da energia consumida com a mobilidade em si, o ar condicionado é o maior consumidor. O sistema de climatização para aplicações automotivas tem características particulares, diferentes de sistemas de climatização para outros ambientes. Em uma aplicação automotiva a variação de condições é bastante significativa, como por exemplo, a carga solar que é imposta, a velocidade do veículo, umidade do ar, as temperaturas interna e externa, variação do número e da posição dos ocupantes no interior do veículo, diferentes regimes de rotação e carga do motor, etc. O sistema deve, portanto, ser projetado para funcionar sob todas estas condições e propiciar condições de conforto térmico com o menor consumo de energia. No presente trabalho o objetivo é o projeto e a simulação de um ciclo de refrigeração que atenda aos requerimentos de carga térmica para um automóvel compacto em um ensaio específico realizado em túnel de vento. A partir da carga térmica, o ciclo de refrigeração é dimensionado seguindo-se o procedimento de projeto, que engloba o dimensionamento dos componentes principais como compressor, condensador, evaporador e o dispositivo de expansão. Os resultados dos cálculos teóricos são comparados com o dimensionamento do veículo real, permitindo se chegar a conclusões sobre o projeto. A avaliação do desempenho do sistema projetado é realizada por meio de um procedimento de simulação proposto, e os resultados comparados com os do veículo testado. O objeto de estudo é o sistema de refrigeração de um veículo compacto de quatro portas de fabricação nacional, submetido a um teste de desempenho do ciclo em um túnel de vento. O procedimento de dimensionamento pode ser usado para o projeto básico do sistema de refrigeração. Os resultados obtidos com o modelo de simulação proposto são bastante razoáveis. O modelo pode ser utilizado para prever o resultado de modificações no ciclo de refrigeração, como a troca de componentes, ou mesmo para prever o funcionamento do sistema sob outras condições de operação. A utilização do modelo fica restrita aos limites da validade dos modelos semi-empíricos dos componentes, não sendo recomendada a utilização fora desses limites. Ainda assim, a faixa de aplicação é grande o suficiente para simular a maioria das condições de trabalho encontradas na climatização veicular. / Human being spends a large amount of energy to satisfy its comfort needs. In the automotive applications, air conditioning is the second larger energy consumption system, after the mobility system itself. The refrigeration system for automotive application has peculiar characteristics, which are different from other refrigeration systems (e.g. buildings, food refrigeration, etc). In an automotive application, variation of several conditions are highly significant, such as the sun load, ambient temperature and humidity, the number and position of the occupants inside the vehicle, different engine loads and speeds and so on. The system must, therefore, be designed to operate satisfactorily under all these conditions and to provide thermal comfort with smallest possible energy consumption. The objective of this work is to present the project and simulation of a refrigeration cycle for a compact size vehicle in order to meet thermal load requirements of a specific wind tunnel test. From the thermal load, the refrigeration cycle is designed according to a design procedure, which includes the sizing of main components such as compressor, condenser, evaporator and expansion device. The results of the calculations are compared with the actual vehicle design. The performance evaluation is achieved by using a proposed simulation procedure, and the simulation results are compared with the actual vehicle test results. The study is conducted on the refrigerating system of a 4-door compact size vehicle locally manufactured, which was submitted to a refrigeration cycle performance test in a wind tunnel. The design procedure can be used for sizing a baseline refrigeration cycle. The results achieved with the proposed simulation model are acceptable. The model can be used to predict the impact of a modification in refrigeration cycle such as a component change, or even to predict the system balance point under different operating conditions. The application of the model is restricted to the range of validation of the component semiempirical models, so that the use beyond these limits is not recommended. The range of application, however, is wide enough to accommodate most of the operating conditions found in the vehicular refrigeration applications.
164

CHARACTERIZATION OF ROTARY BELL ATOMIZERS THROUGH IMAGE ANALYSIS TECHNIQUES

Wilson, Jacob E. 01 January 2018 (has links)
Three methods were developed to better understand and characterize the near-field dynamic processes of rotary bell atomization. The methods were developed with the goal of possible integration into industry to identify equipment changes through changes in the primary atomization of the bell. The first technique utilized high-speed imaging to capture qualitative ligament breakup and, in combination with a developed image processing technique and PIV software, was able to gain statistical size and velocity information about both ligaments and droplets in the image data. A second technique, using an Nd:YAG laser with an optical filter, was used to capture size statistics at even higher rotational speeds than the first technique, and was utilized to find differences between serrated and unserrated bell ligament and droplet data. The final technique was incorporating proper orthogonal decomposition (POD) into image data of a side-profile view of a damaged and undamaged bell during operation. This was done to capture differences between the data sets to come up with a characterization for identifying if a bell is damaged or not for future industrial integration.
165

AN ANALYSIS OF RESISTANCE SPOT WELD QUALITY BASED ON ACOUSTIC AND ELECTRICAL SIGNATURES

Butler, Ivan Charles 01 January 2019 (has links)
The union of a set of materials by way of Resistance Spot Welding is designed so that once fused together, a substantial amount of intentional, external force must be applied to separate the contents. Therefore, Resistance Spot Welding is often the preferred fusion method in high-volume manufacturing processes. The result of Resistance Spot Welding however is the formation of a weld nugget which is not visible to the naked eye. Destructive and/or ultrasonic methods applied off-line must be used to determine the quality of each weld; both inefficient and expensive processes. The following research analyzes the data fed back during resistance spot weld sequences in-line and establishes a correlation between emitted characteristics and the final quality of a spot weld. The two characteristics researched to segregate weld quality are: the electrical sin wave signature and the acoustic sin wave signature produced during the welding sequence. Both features were discovered to have a direct correlation to the final quality of a weld once cured. By measuring and comparing these characteristics at the source, an opportunity is presented to decrease time and potential defects by confirming the quality of each weld in-process and at the source.
166

Cooling Strategy for Effective Automotive Power Trains: 3D Thermal Modeling and Multi-Faceted Approach for Integrating Thermoelectric Modules into Proton Exchange Membrane Fuel Cell Stack

January 2014 (has links)
abstract: Current hybrid vehicle and/or Fuel Cell Vehicle (FCV) use both FC and an electric system. The sequence of the electric power train with the FC system is intended to achieve both better fuel economies than the conventional vehicles and higher performance. Current hybrids use regenerative braking technology, which converts the vehicles kinetic energy into electric energy instead of wasting it. A hybrid vehicle is much more fuel efficient than conventional Internal Combustion (IC) engine and has less environmental impact The new hybrid vehicle technology with it's advanced with configurations (i.e. Mechanical intricacy, advanced driving modes etc) inflict an intrusion with the existing Thermal Management System (TMS) of the conventional vehicles. This leaves for the opportunity for now thermal management issues which needed to be addressed. Till date, there has not been complete literature on thermal management issued of FC vehicles. The primary focus of this dissertation is on providing better cooling strategy for the advanced power trains. One of the cooling strategies discussed here is the thermo-electric modules. The 3D Thermal modeling of the FC stack utilizes a Finite Differencing heat approach method augmented with empirical boundary conditions is employed to develop 3D thermal model for the integration of thermoelectric modules with Proton Exchange Membrane fuel cell stack. Hardware-in-Loop was designed under pre-defined drive cycle to obtain fuel cell performance parameters along with anode and cathode gas flow-rates and surface temperatures. The FC model, combined experimental and finite differencing nodal net work simulation modeling approach which implemented heat generation across the stack to depict the chemical composition process. The structural and temporal temperature contours obtained from this model are in compliance with the actual recordings obtained from the infrared detector and thermocouples. The Thermography detectors were set-up through dual band thermography to neutralize the emissivity and to give several dynamic ranges to achieve accurate temperature measurements. The thermocouples network was installed to provide a reference signal. The model is harmonized with thermo-electric modules with a modeling strategy, which enables optimize better temporal profile across the stack. This study presents the improvement of a 3D thermal model for proton exchange membrane fuel cell stack along with the interfaced thermo-electric module. The model provided a virtual environment using a model-based design approach to assist the design engineers to manipulate the design correction earlier in the process and eliminate the need for costly and time consuming prototypes. / Dissertation/Thesis / Masters Thesis Technology 2014
167

Modeling and Measuring Cognitive Load to Reduce Driver Distraction in Smart Cars

January 2015 (has links)
abstract: Driver distraction research has a long history spanning nearly 50 years, intensifying in the last decade. The focus has always been on identifying the distractive tasks and measuring the respective harm level. As in-vehicle technology advances, the list of distractive activities grows along with crash risk. Additionally, the distractive activities become more common and complicated, especially with regard to In-Car Interactive System. This work's main focus is on driver distraction caused by the in-car interactive System. There have been many User Interaction Designs (Buttons, Speech, Visual) for Human-Car communication, in the past and currently present. And, all related studies suggest that driver distraction level is still high and there is a need for a better design. Multimodal Interaction is a design approach, which relies on using multiple modes for humans to interact with the car & hence reducing driver distraction by allowing the driver to choose the most suitable mode with minimum distraction. Additionally, combining multiple modes simultaneously provides more natural interaction, which could lead to less distraction. The main goal of MMI is to enable the driver to be more attentive to driving tasks and spend less time fiddling with distractive tasks. Engineering based method is used to measure driver distraction. This method uses metrics like Reaction time, Acceleration, Lane Departure obtained from test cases. / Dissertation/Thesis / presentation / REACTION TIMES / DRIVING DATA RESULTS / Masters Thesis Computer Science 2015
168

Implicações da estratégia modular no processo de capacitação e na transferência de atividades de desenvolvimento de produto entre os fornecedores de nível 1 e 2 da cadeia automotiva. / The modular strategy implications in the capability process and in the transfer of product development activities among the first and second tier suppliers of the automotive chain.

Evandro Prieto 14 August 2007 (has links)
O desenvolvimento de novos produtos no contexto da estratégia modular implica em uma redistribuição das atividades inerentes a este processo, devido à decomposição das tarefas de desenvolvimento do projeto entre as montadoras e seus fornecedores. Neste contexto, o presente trabalho investiga as implicações da estratégia modular no processo de capacitação e na transferência de atividades de Desenvolvimento de Produto (DP) entre os fornecedores de nível 1 e 2 da cadeia automotiva de suprimentos. A pesquisa se desenvolve por meio da abordagem de estudo de casos múltiplos, realizado em quatro empresas do setor automotivo. O modelo de progressividade de competências modulares foi aplicado nas empresas selecionadas e permitiu identificar graus distintos de maturidade modular. O grau de maturidade nas competências modulares apresentadas nestas empresas determina, ao mesmo tempo, o processo de transferência de atividades e a intensidade do envolvimento nas práticas de desenvolvimento de produtos com seus clientes. A pesquisa constatou que quanto maior o grau de maturidade modular, maior a tendência dos fornecedores da cadeia automotiva de participar em projetos de DP das montadoras em sistema de parceria e mediante investimentos de risco. A pesquisa constatou que quanto maior o grau de maturidade modular, maior a tendência dos fornecedores da cadeia automotiva de participar em projetos de DP das montadoras em sistema de parceria e mediante o compartilhamento do risco nos investimentos. / The new product development in the context of the modular strategy implies in a redistribution of the inherent activities of this process, being based on the decomposition and division of the project tasks developed among the assemblers and theirs suppliers. In accordance to this context, the present work investigate the implications of the modular strategy in the transference processes related to the Product Development (PD) activities that happens between the 1rst and 2nd tier of the automotive chain. The research is developed by the approach of multiple case studies, carried through in four companies of the automotive sector. The maturity level of modular competences on these suppliers in such a way determines, at the same time, the processes of transference of activities and the supplier\'s involvement in the product development activities. In accordance with the analysis of this work was possible identify that the modular strategy is promoting the improvement in the relationship among the OEM (Original Equipment Manufacturers) and the suppliers positioned in the modular stages of development and maturity. The research identified that the modular maturity level implies in the involvement level in PD projects of the OEM with the system of partnership and with the sharing of investment risks.
169

Dimensionamento e avaliação do ciclo de refrigeração de sistema de climatização automotivo. / Sizing and evaluation of an automotive climate system refrigeration cycle.

Eduardo Oliveira dos Santos 02 September 2005 (has links)
O ser humano consome grandes quantidades de energia para satisfazer as suas necessidades de conforto. Dentro do setor automotivo, depois da energia consumida com a mobilidade em si, o ar condicionado é o maior consumidor. O sistema de climatização para aplicações automotivas tem características particulares, diferentes de sistemas de climatização para outros ambientes. Em uma aplicação automotiva a variação de condições é bastante significativa, como por exemplo, a carga solar que é imposta, a velocidade do veículo, umidade do ar, as temperaturas interna e externa, variação do número e da posição dos ocupantes no interior do veículo, diferentes regimes de rotação e carga do motor, etc. O sistema deve, portanto, ser projetado para funcionar sob todas estas condições e propiciar condições de conforto térmico com o menor consumo de energia. No presente trabalho o objetivo é o projeto e a simulação de um ciclo de refrigeração que atenda aos requerimentos de carga térmica para um automóvel compacto em um ensaio específico realizado em túnel de vento. A partir da carga térmica, o ciclo de refrigeração é dimensionado seguindo-se o procedimento de projeto, que engloba o dimensionamento dos componentes principais como compressor, condensador, evaporador e o dispositivo de expansão. Os resultados dos cálculos teóricos são comparados com o dimensionamento do veículo real, permitindo se chegar a conclusões sobre o projeto. A avaliação do desempenho do sistema projetado é realizada por meio de um procedimento de simulação proposto, e os resultados comparados com os do veículo testado. O objeto de estudo é o sistema de refrigeração de um veículo compacto de quatro portas de fabricação nacional, submetido a um teste de desempenho do ciclo em um túnel de vento. O procedimento de dimensionamento pode ser usado para o projeto básico do sistema de refrigeração. Os resultados obtidos com o modelo de simulação proposto são bastante razoáveis. O modelo pode ser utilizado para prever o resultado de modificações no ciclo de refrigeração, como a troca de componentes, ou mesmo para prever o funcionamento do sistema sob outras condições de operação. A utilização do modelo fica restrita aos limites da validade dos modelos semi-empíricos dos componentes, não sendo recomendada a utilização fora desses limites. Ainda assim, a faixa de aplicação é grande o suficiente para simular a maioria das condições de trabalho encontradas na climatização veicular. / Human being spends a large amount of energy to satisfy its comfort needs. In the automotive applications, air conditioning is the second larger energy consumption system, after the mobility system itself. The refrigeration system for automotive application has peculiar characteristics, which are different from other refrigeration systems (e.g. buildings, food refrigeration, etc). In an automotive application, variation of several conditions are highly significant, such as the sun load, ambient temperature and humidity, the number and position of the occupants inside the vehicle, different engine loads and speeds and so on. The system must, therefore, be designed to operate satisfactorily under all these conditions and to provide thermal comfort with smallest possible energy consumption. The objective of this work is to present the project and simulation of a refrigeration cycle for a compact size vehicle in order to meet thermal load requirements of a specific wind tunnel test. From the thermal load, the refrigeration cycle is designed according to a design procedure, which includes the sizing of main components such as compressor, condenser, evaporator and expansion device. The results of the calculations are compared with the actual vehicle design. The performance evaluation is achieved by using a proposed simulation procedure, and the simulation results are compared with the actual vehicle test results. The study is conducted on the refrigerating system of a 4-door compact size vehicle locally manufactured, which was submitted to a refrigeration cycle performance test in a wind tunnel. The design procedure can be used for sizing a baseline refrigeration cycle. The results achieved with the proposed simulation model are acceptable. The model can be used to predict the impact of a modification in refrigeration cycle such as a component change, or even to predict the system balance point under different operating conditions. The application of the model is restricted to the range of validation of the component semiempirical models, so that the use beyond these limits is not recommended. The range of application, however, is wide enough to accommodate most of the operating conditions found in the vehicular refrigeration applications.
170

Estudo de otimização de um sistema limpador de para-brisa. / Windshield wiper system optimization.

Sueli Kratz 01 October 2015 (has links)
A concorrência no mercado automotivo vem aumentando nos últimos 10 anos, o que tem exigido das montadoras maior agilidade no desenvolvimento e lançamento de novos veículos, os quais devem atender aos requisitos e desejos dos clientes. Devido a isso, o uso de recursos e métodos no desenvolvimento que objetivem o atendimento aos requisitos de projeto, exigindo menos tempo para alcançar resultados satisfatórios e com menor custo desde as primeiras fases são diferenciais positivos para o novo projeto. O objeto de estudo do presente trabalho é o sistema limpador de para-brisa, e tem por objetivo propor uma metodologia computacional de otimização do sistema limpador de para-brisa a fim de obter a maximização da área de limpeza ao mesmo tempo em que encontra a configuração ótima do mecanismo considerando a sua mobilidade, o espaço disponível na carroceria para sua fixação e a qualidade do movimento oscilatório das palhetas. O desenvolvimento do modelo de otimização foi realizado em duas etapas, sendo a primeira a da otimização do posicionamento e orientação das palhetas visando a maximização da área de limpeza, e a segunda, a da otimização do mecanismo, onde buscou-se encontrar as dimensões ideais das peças do mecanismo, com o objetivo de maximizar os cursos de atuação das palhetas, limitando as amplitudes máximas das velocidades e acelerações angulares destas peças. A avaliação da metodologia foi realizada utilizando o programa MATLAB®, e como dados de entrada foram considerados sistemas limpadores de para-brisa existentes. Os resultados apresentados foram satisfatórios, pois a área de limpeza foi maximizada como também o mecanismo foi otimizado respeitando os limites impostos através de restrições. A metodologia proposta se mostrou uma potencial ferramenta de apoio no desenvolvimento de novos projetos, desde suas fases iniciais. / The competition among several existent brands of automobile industry has highly increased over the last 10 years. It leads all the companies to adopt methods to develop new models in a shorter period of time, but also focused on project requirements, quality and costs in order to satisfy the costumer. The main goal of this work is to propose a computational methodology optimization of the windshield wiper system in order to achieve the maximum wiped area by optimizing wiper blades lengths and orientations. Parallel to that, constrains make the methodology finds the optimum kinematic design for the windshield wiper linkage in terms of mobility, available area to fix the linkage on body and the maximum range of the blades oscillatory motion. The development has two stages: the first is the positioning and orientation of the blades optimization in order to maximize the cleaning area, and the second is the mechanism optimization, where it tries to find the optimum length of the mechanism`s links, also in order to maximize the cleaning area, at the same time it controls the maximum amplitudes of the angular accelerations and speeds of these links. The methodology evaluation was performed using the MATLAB® applied on an existent windshield wiper system of a domestic passenger car The results were satisfactory, since the cleaning area was maximized as well as the mechanism has been optimized within the imposed limits by constrains. The developed methodology has proved to be a potential tool in developing new projects, since the early phases of vehicle development.

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