A abertura do mercado brasileiro e o fenômeno da globalização observado nos últimos anos, influenciaram em que as quatro tradicionais empresas do setor automobilístico (VW, Ford, FIAT e GM) passassem a dividir a participação de mercado brasileiro com os concorrentes estrangeiros. Devido a este fato, a demanda por qualidade e confiabilidade nos produtos oferecidos cresceu continuamente. Nenhuma empresa gosta de gastar com garantia, isto significa que algo saiu errado, um cliente está insatisfeito e isto custará à montadora. Deste modo as empresas automotivas necessitam desenvolver veículos com qualidade superior e com menores custos e para isso utilizam diversas ferramentas de engenharia. Atingir a satisfação dos clientes, melhorar a qualidade de seus produtos, reduzir custo de garantia tem sido a missão de todas as empresas no mercado brasileiro e em especial nas empresas do setor automobilístico, já que os principais fatores na decisão de compra de um veículo tem sido preço e confiabilidade, torna-se necessário oferecer cada vez mais opções de escolha para os clientes e acredita-se que a extensão da garantia oferecida pela empresa automotiva pode ser um fator decisivo de compra. Portanto o objetivo deste estudo é desenvolver um modelo para descrever o comportamento de um produto e predizer sua confiabilidade no campo. O modelo considera a utilização dos dados de reclamações de garantia, incluindo a consideração da existência de veículos que não apresentaram falhas ao final deste período. De posse da estimativa da confiabilidade do veículo ou subsistema e considerando os recursos gastos com falhas no período de garantia, propõe-se um modelo de análise baseado nos conceitos da Teoria da Decisão, que permite avaliar o efeito da extensão da garantia sobre o valor monetário economizado do total reservado para os gastos com garantia. Esta análise subsidia unicamente a tomada de decisão estratégica a respeito da viabilidade da extensão da garantia de um veículo. O modelo ora proposto é aplicado no intuito da extensão da garantia do conjunto motor e transmissão de um veículo popular. / As the Brazilian market opened to foreigner automakers and the phenomenon of globalization started some years ago, the four traditional automakers began to share its market with many others competitors. As a result, demand for quality and reliability on products offered to the customers grew continuously and it is more perceptive on the automobile business. Nobody likes warranty expenses; it is a universally recognized evil. It means that something went wrong, a customer is not satisfied and it probably will cost to the manufacturer. As it happens, automakers need to develop vehicles with superior quality, less manufacturing costs and better processes, shorten development process and to accomplish this goal it is necessary to use engineering tools available as much as possible. Many companies are setting as their goal: customer satisfaction, quality improvement, warranty cost reduction and it happens more often on the automobile market that is because reliability and warranty became one of the key points when making decisions of purchasing a vehicle. Today it is necessary to offer more options to the customers so they can decide which one is the best deal for them. It is believed that warranty extension already offered by some companies in this market can be a significant differential on the moment of a purchase decision in buying a vehicle. Therefore, the main objective of this study is to develop a model to describe the behavior of a product and predict its reliability in the field. The model considers the use of warranty claims and also the use of a number of vehicles which did not have any warranty claim in the subsystem under analysis. As one have the subsystem predicted reliability and the expenses on warranty failures occurred during their warranty period, it is possible to draw a model based on the concept of Decision Theory which allows the analysis of warranty extention effects over the warranty accrual. This analysis only helps on the decision making strategy regarding the warranty extention feseability. The model proposed on this study is applied for warranty extention of the subsystems engine and transmission.

O objetivo deste estudo foi de analisar a confiabilidade teste reteste do posicionamento dos eletrodos na aquisição do sinal eletromiográfico dos músculos do antebraço na tarefa de preensão palmar, por meio de dois posicionamentos. O primeiro posicionamento proposto por Cram; Durie e o segundo proposto por Mogk; Keir. Foram recrutados 30 voluntários sendo divididos em 2 grupos com 15 indivíduos cada. O primeiro grupo era formado por indivíduos saudáveis, isto é, que não apresentavam qualquer patologia, trauma ou dor no membro superior. Este grupo era composto por 13 mulheres e 2 homens com idade média de 23,4 anos, sendo 13 destros e 2 canhotos. O segundo grupo era formado por indivíduos que apresentavam algum trauma no antebraço, punho ou mão, recrutados no centro de reabilitação e no ambulatório de cirurgia do membro superior do Hospital das Clínicas da Faculdade de Medicina de Ribeirão Preto da Universidade de São Paulo. A amostra era composta por 13 homens e 2 mulheres com idade média de 34,6 anos, sendo 14 destros e 1 canhoto. Todos os participantes assinaram o Termo de Consentimento Livre e Esclarecido. O procedimento foi realizado em dois dias com diferença de 24h entre as avaliações. A avaliação consistia em realizar a tarefa de preensão palmar com o dinamômetro analógico da marca Jamar® , realizando a máxima contração voluntária pelo período de 10 segundos com repouso de 3 minutos entre cada preensão, sendo coletados o sinal eletromiográfico de sete canais dos músculos do antebraço volar e dorsal, segundo cada método. Foi analisada a confiabilidade pelo índice de ICC e o SEM (Standard Error of Measurement). Os resultados obtidos mostram excelente correlação entre os dois posicionamentos em ambos os grupos. Quando verificado o valor de ICC do grupo de saudáveis verificou valores acima de 0.75 em todos os canais, o que demonstrou uma alta correlação entre as medidas em ambos os posicionamentos, com pequeno SEM. No grupo pacientes foi observado que nos músculos FUC, FSD e ERC uma correlação moderada para o posicionamento Mogk; Keir e somente no músculo FRC apresentou correlação moderada no posicionamento Cram; Durie. Os gráficos de Bland e Altman mostraram alta concordância entre as medidas, visto que, em ambos os posicionamentos, os valores ficaram entre o intervalo de confiança de 95% e próximos da linha média. Como conclusão pode-se inferir que ambos os posicionamentos apresentaram alta confiabilidade e alta correlação quando avaliado por meio do teste e re-teste, podendo ser utilizados para medida eletromiográfica dos músculos do antebraço / The objective of this study was to analyze test retest reliability of the electrodes placement in the acquisition of electromyography forearm muscles during a isometric hand grip task, through two different methods. The first method was proposed by Cram; Durie and the second by Mogk; Keir. We recruited 30 volunteers divided into 2 groups with 15 subjects each. The first group consisted of healthy subjects, who did not show any pathology, trauma or pain in the upper extremity. This group consisted of 13 women and 2 men with a mean age of 23.4 years, and 13 right-handed and 2 left-handed. The second group consisted of individuals who had previous trauma on the forearm, wrist or hand. They were recruited from the rehabilitation center and upper limb surgery clinic of the Medical School of Ribeirão Preto Clinical Hospital. The sample consisted of 13 men and 2 women with a mean age of 34.6 years, 14 right-handed and left-handed one. All participants signed the consent form. The procedure was performed in two days with 24 hours difference between assessments. The evaluation was to carry by a isometric handgrip task with a analog dynamometer Jamar®, with maximum voluntary contraction for 10 seconds with 3 minutes of rest and analised by CCI and SEM (Standard Error of Measurement) . The results obtained have a high correlation between the two methods in both groups. Analyzing the ICC value of the healthy group value noted above 0.75 in all channels, demonstrating a excelent correlation between the measurements in both positions and low SEM. Checking in group patients realize that the FUC, FSD and ERC muscles has a moderate correlation for Mogk; Keir positioning and only on FRC showed moderate correlation in Cram; Durie electrode placement method. Analyzing Bland and Altman method a high concordance was found between the measures, since in both positions, the values were between the confidence interval of 95% and close to the midline. Through this we can infer that both positions have high reliability and high correlation when measured by the test and retest

O objetivo deste estudo foi avaliar a confiabilidade intradia e interdias dos valores de amplitude da eletromiografia de superfície, dos músculos da cintura escapular e membro superior, durante a realização de 3 exercícios isométrico com a extremidade distal do segmento fixa em uma superfície estável e outra superfície instável, com descarga de peso axial controlada para o membro superior. Para tanto, 20 adultos saudáveis realizaram os exercícios push-up, bench-press e wall-press em diferentes níveis de carga (80 e 100% da carga máxima). Os valores de carga produzida por cada um dos exercícios foram registrados de maneira simultânea à eletromiografia. Os sujeitos realizaram três contrações voluntárias máximas (CVM) na posição de prova de função muscular de cada músculo, para obtenção do valor de referência para normalização dos valores de root mean square (RMS) e da integral do envoltório linear (?env). Os sujeitos foram instruídos, a realizarem de forma aleatória, 3 séries de contrações isométricas por 6 segundos em cada exercício, com intervalo de 2 minutos entre as séries e exercícios.Os sinais eletromiográficos dos músculos deltóide porção anterior e posterior, trapézio fibras superiores, serrátil anterior, peitoral maior porção clavicular, bíceps braquial porção longa e tríceps braquial porção longa foram captados por eletrodos de superfície ativos simples diferenciais, realizados em dois testes com intervalo de sete dias. Os dados foram coletados com freqüência de amostragem de 4000Hz e aplicados filtros digitais de passa baixa de 500Hz e passa alta de 20Hz. Os valores de RMS e ?env foram normalizados pelo valor máximo da amplitude eletromiográfica obtida em 1 das 3 CVM do músculo correspondente. As confiabilidades intradia e interdias foram calculadas através do coeficiente de correlação intraclasse (ICC), erro padrão da medida (SEM) e coeficiente de variação (CV). Os resultados indicaram excelente confiabilidade intradia dos valores de amplitude eletromiográfica (ICC ?0,75). A confiabilidade interdias dos valores normalizados de RMS apresentou valores variando entre bom e excelente (ICC 0,52-0,98), já os valores normalizados de ?env apresentaram valores pobres a excelente de confiabilidade (ICC 0,06-0,93). Os valores de carga produzidos durante os exercícios apresentaram excelente confiabilidade intradia e interdias (ICC ?0,97). Por fim, os resultados do presente estudo sugerem que a confiabilidade dos valores normalizados de amplitude eletromiográfica dos músculos analisados apresentam valores mais confiáveis durante os exercícios realizados com superfície estável. Já os níveis de carga empregados (80 e 100%) durante os exercícios parecem não ter influenciado nos níveis de variabilidade, talvez por serem cargas muito próximas. / The objective of the present study was to evaluate the intra and interday reliability of surface electromyography amplitude values of the scapular girdle muscles and upper limbs during the performance of 3 isometric exercises of closed kinetic chain regarding the upper limbs with the fix distal segment extremity on one stable surface and the other one on one unstable surface. In this regard, 20 healthy adults realized the exercises push-up, bench-press and wall-press with different load levels (80 and 100% maximal load). The load values produced for each exercise were recorded simultaneously to the electromyography. The individuals performed three maximal voluntary contractions (MVC) in the muscular testing position of each muscle for the obtainment of the reference value for the root mean square (RMS) normalization values and for the integrated of the linear envelope (?env). The individuals were instructed to realize at random, 3 isometric contraction series taking each exercise 6 seconds with a rest of 2 minutes between the series and the exercises. The electromyographic signals of the anterior and posterior deltoid, upper trapezius, anterior serratus, pectoralis major, biceps and triceps brachial muscle were captured by simple active differential surface electrodes, in two tests with a 7-day interval. Data were collected with a sampling frequency of 4000Hz and 500Hz low and 20Hz high passage digital filters. The RMS and ?env values were normalized by the maximal electromyographic amplitude value obtained in 1 of the 3 MVC of the corresponding muscle. The intra and interday reliabilities were calculated through the intraclass correlation coefficient (ICC), standard error measure (SEM) and coefficient of variation (CV). The results indicated an excellent intraday reliability of the electromyographic amplitude values (ICC ?0.75). The interday reliability of the RMS normalized values presented values varying between good and excellent (ICC 0.52-0.98), whereas the ?env normalized values presented poor to excellent reliability values (ICC 0.06-0.93). The load values produced during the exercises presented excellent intra and interdays reliability. Finally, the results of the present study suggest that the reliability of the electromyographic amplitude normalized values of the analyzed muscles present better values during the performance of the exercises with stable surface. However the load levels utilized during the exercises do not seem to have influenced the variability levels, eventually in view of being very close levels

Solar thermal energy harvesting is a promising solution to offset the electricity demands of a growing population. The use of the technology is however still limited and this can most likely be attributed to the capital cost and also the intermittent nature of solar energy which requires incorporation of a storage system. To make the technology more attractive and effective, cheap means of harvesting solar energy and the development of efficient and inexpensive thermal energy storage devices will improve the performance of solar energy systems and the widespread use of solar energy. Heat storage in a packed-bed rock with air as the working fluid presents an attractive and simple solution for storing solar thermal energy and it is recommended for solar air heaters. A packed-bed rock storage system consists of rocks of good heat capacity packed in a storage tank. The working fluid (air) flows through the bed to transfer its energy. The major concern of the design for a packed-bed rock thermal storage system is to maximize the heat transfer and minimise the pressure drop across the storage tank and hence the pumping power. The time duration the stored energy can be preserved and the air flow wall effect through the bed are the common complications encountered in this system. This study presents an experimental and analytical analysis of a vacuum storage tank with the use of expanded perlite for high temperature thermal energy storage in a packed-bed of rocks. Dolerite rocks are used as the storage medium due to their high heat capacity and as they are locally available. To minimise the pressure drop across the tank, moderate rock sizes are used. The tank contains baffles, allowing an even spread of air to rock contact through the entire tank, therefore improving heat transfer. There is a good correlation between the predicted and the actual results (4 percent) which implies that the baffles incorporated inside the vacuum tank forces the air through the entire tank, thereby resulting in an even lateral temperature distribution across the tank. The investigation of heat loss showed that a vacuum with expanded perlite is a viable solution to high temperature heat storage for an extended period. The research also focuses on the investigation of a proposed low cost parabolic trough solar collector for an air heating system as shown in Figure (1.3). The use of a standard solar geyser evacuated tube (@R130 each) has cost benefits over the industry standard solar tubes normally used in concentrating solar power systems. A mathematical was developed to predict the thermal performance of proposed PTC and it was found that the measured results compared well with the predictions. The solar energy conversion efficiency of this collector is up to 70 percent. This research could impact positively on remote rural communities by providing a source of clean energy, especially for off-grid applications for schools, clinics and communication equipment. It could lead to a significant improvement in the cost performance, ease of installation and technical performance of storage systems for solar heating applications.

Hydrogen fuel cells have the potential to dramatically reduce emissions from the energy sector, particularly when integrated into an automotive application. However, there are three main hurdles to the commercialisation of this promising technology; one of which is reliability. Cur- rent standards require an automotive fuel cell to last around 5000 h of operation (equivalent to around 150,000 miles), which has proven difficult to achieve to date. This hurdle can be overcome through in-depth reliability analysis including techniques such as Failure Mode and Effect Analysis (FMEA), Fault Tree Analysis (FTA) and Petri-net simulation. This research has found that the reliability field regarding hydrogen fuel cells is still in its infancy, and needs development, if the current standards are to be achieved. In this research, a detailed reliability study of a Polymer Electrolyte Membrane Fuel Cell (PEMFC) is undertaken. The results of which are a qualitative and quantitative analysis of a PEMFC. The FMEA and FTA are the most up to date assessments of failure in fuel cells developed using a comprehensive literature review and expert opinion. Advanced modelling of fuel cell degradation logic was developed using Petri-net modelling techniques. 20 failure modules were identfied that represented the interactions of all failure modes and operational parameters in a PEMFC. Petri-net simulation was used to overcome key pitfalls observed in FTA to provide a verfied degradation model of a PEMFC in an automotive application, undergoing a specific drive cycle, however any drive cycle can be input to this model. Overall results show that the modeled fuel cell's lifetime would reach 34 hours before falling below the industry standard degradation rate of more than 5%. The degradation model has the capability to simulate fuel cell degradation under any drive cycle and with any operating parameters. A fuel cell test rig was also developed that was used to verify the simulated degradation. The rig is capable of testing single cells or stacks from 0-470W power. The results from the verification experimentation agreed strongly with the degradation model, giving confidence in the accuracy of the developed Petri-net degradation model. This research contributes greatly to the field of reliability of PEMFCs through the most up-to-date and comprehensive FMEA and FTA presented. Additionally, a degradation model based upon Petri-nets is the first degradation model to encompass a 1D performance model to predict fuel cell life time under specific drive cycles.

No description available.

Abstract The rapid growth in the wireless communications markets together with the emerging need for high-bit-rate (≫ 100 Mb/s) multimedia/data services are pushing the usage of radio spectrum resources below 10 GHz to the uttermost limit. The lack of bandwidth has led to an extensive development of mobile/fixed BWA systems for the higher microwave and millimetre-wave regions up to the V-band frequencies (50–75 GHz). In order for these systems to have mass deployment and to meet cost-sensitive consumer markets’ requirements, their cost and size must be reduced from current levels. One of the most viable packaging approaches to satisfy these demands is the low-temperature co-fired ceramic (LTCC) based system-in-package (SiP) module technology combined with fully automated surface-mount assembly techniques. However, one of the main challenges of this approach has been previously associated with the broadband radio frequency (RF) and reliability performance constraints of the board-level solder joints in LTCC/PCB assemblies. In this thesis the primary focus is to tackle these limitations and significantly extend the feasibility of the LTCC module technology to various wireless/mixed-signal packaging applications. The thesis is divided into three main parts. In the first part, design, modelling and implementation of vertical package transitions (BGA, flip-chip, substrate via) over a very wide frequency range are presented. In the second part, the emphasis is on the improvement of the thermal fatigue endurance of the board-level solder joints in the LTCC/PCB assemblies. In the last part, the results are merged to realize a high-performance LTCC module platform for use in a wide variety of SiP products in the telecommunication sector. The flip-chip, substrate-via and BGA transition structures exhibited excellent signal transmission properties up to the V-band frequencies. The developed equivalent circuit models of the transitions matched well with the measurements. Cascading the transitions together allows the building of different combinations of vertical interconnection paths in SiP modules. To demonstrate this, a surface-mountable LTCC filter package for K-band radio link frequencies was implemented. The developed composite BGA solder joint structure with plastic-core solder balls significantly enhanced the thermal fatigue life in LTCC/PCB assemblies in different thermal cycling conditions, indicating adequate board-level reliability for many practical LTCC-BGA packaging applications. Moreover, electromagnetic analysis showed that the use of the plastic-core solder ball has no detrimental impact on the RF performance of the solder joint. Finally, based on the obtained results a reliable lead-free LTCC-BGA module platform was developed for broadband packaging applications. The BGA module platform with a size of 15 mm × 15 mm included 38 low-frequency and two wideband RF input/output connections up to the K-band frequencies. The module structure also allowed plenty of space to mount discrete SMD/bare-die components on the surface and/or to embed passive components in the 1.2 mm thick substrate. Preliminary thermal cycling results of the soldered LTCC/PCB assemblies demonstrated sufficient reliability for telecommunication applications. Therefore, the presented module platform can serve as a physical building block for various wireless/mixed-signal SiP products, and hence significantly reduce their development time and associated costs.

Abstract Good postural stability is needed during most activities in daily life. Balance can be improved with specific training programmes in physiotherapy. The goals of treatment differ, depending on the subject's age and disorders. In clinical practice, postural stability is commonly evaluated by scaled functional tests or by recording body sway on a platform. On the basis of therapeutic modalities, information of separate movements of body segments would be important. The data might be useful in developing balance evaluation and training programmes in physiotherapy. The aim of this project was to present one method and to estimate its reliability and validity in studying the movements of separate body segments in postural control. In addition, the association between age, gender and anthropometric factors and the movements of separate body segments during quiet stance with the eyes open and closed were studied in a group of healthy subjects. A method was developed to measure the body movements during standing with a motion analysis system, and the reliability of body movement measurements was evaluated. The validity of the motion analysis measurements was evaluated to compare the balancing body measurements during stance on two legs and on one leg obtained with a motion analysis system and a platform. In cross-sectional studies, 100 healthy randomly selected subjects were stratified into ten groups (by age and gender). The body movements of all subjects standing on two legs with the eyes open and closed were measured using a motion analysis system and calculated as maximal and total movements. The movement velocities and accelerations were analysed and compared between the eyes open and eyes closed conditions. The associations between movement values and age and gender were analysed. In addition, the body anthropometrics of the subjects were measured and the relations between the body characteristics and the body balancing movements were calculated using regression analysis. The results showed that motion analysis can be used in measuring body movements in postural stability. Better reproducible balance measurement results are obtained with the total movement values than with the maximal amplitude values. In a comparison of the parameters used in a validity study, motion analysis and platform seemed to reflect the same aspect of balance, although the views of measurement were different. During standing on two legs with the eyes open, there was a statistically significant difference in the maximal anterior-posterior head movement and in the vertical navel movement between the age groups, but the results did not show other statistically significant differences between the balancing movements of separate body segments of the groups or between the balance measurement values of men and women in standing on two legs with the eyes open and closed. It seems that healthy female and male subjects control their stance with quite similar ranges of body adjustment. Body characteristics had slight but considerable effects on the variations of body balancing movements in standing on two legs with the eyes open, but almost none in the eyes-closed conditions. There were differences in the results between the male and female groups. In standing on two legs with the eyes closed, all the measured body parts except the ankles had significantly higher maximal velocity and acceleration values than in standing with the eyes open. The effect of visual information on balancing the body seems to be essential. The results indicated that the motion analysis system is also a useful tool in further balance studies, but the methods of analysis need to be developed. Postural stability should be evaluated and practised even in more demanding balance performances. Movement speed and the special role of each body part in maintaining balance should be paid attention.

The aim of this article was to analyze the construct validity and reliability of the Love Attitude Scale (LAS, Hendrick & Hendrick, 1986). The sample consisted of 381 undergraduate students (61.7 % of them women) between the ages of 17 and 25 years old. The LAS and the I- PANAS - SF (adapted by Gargurevich, 2010) that evaluates positive and negative affect were applied. The exploratory factor analysis resulted in six factors (Eros, Ludus, Storge, Pragma, Mania and Ágape), that explained 47.87 % of the total variance. The correlations between the score of Eros and Pragma styles and positive affect were positive and significant; while Manía and Ludus styles had positive and significant relationships with negative affect. Reliability by the method of internal consistency of the six factors found was from .62 to .85; while the stability coefficients for test- retest method were .44 to .77. These results allow concluding that the LAS and their scores are valid and reliable to measure attitudes toward love in the college population of Lima. / El objetivo de este estudio fue analizar la validez de constructo y la fiabilidad de la Escala de Actitudes sobre el Amor (Love Attitudes Scale [LAS]) de Hendrick & Hendrick (1986). La muestra estuvo compuesta por 381 estudiantes universitarios de Lima, Perú, (61.7 % mujeres) de entre 17 y 25 años de edad. Aparte del LAS, se aplicó el I-PANAS-SF adaptado por Gargurevich (2010), el cual evalúa el afecto positivo y negativo. Como resultados, el análisis factorial exploratorio del LAS arrojó una solución de seis factores (Eros, Ludus, Storge, Pragma, Manía y Ágape) que explicaron el 47.87 % de la varianza total. Las correlaciones entre las puntuaciones de los estilos Eros y Pragma y el afecto positivo fueron positivas y significativas; mientras que los estilos Manía y Ludus tuvieron correlaciones positivas y significativas con el afecto negativo. Utilizando el método de consistencia interna, la fiabilidad de los seis factores encontrados fue de .62 a .85; mientras que con el método testretest, los coeficientes de estabilidad fueron de .44 a .77. Estos resultados permiten concluir que el LAS y sus puntuaciones son una medida válida y fiable para medir las actitudes hacia el amor en la población de universitarios de Lima, Perú.

This dissertation deals with the important issue of reliability management for 3kV DC Traction Substations. A general introduction explaining the changes that took place in the railway environment is followed by a description of the system. Understanding the components of the system is important but care must be taken not to go into too much detail. The level at which the system is broken down will be sufficient for this study. Some relevant reliability theory is discussed and applied to the 3kV DC system. An analysis of the failure modes and criticality helps to identify the components that need special focus during the inspections. With a good understanding of the above aspects a process for the inspection of substations is formulated. To design a process that can be used throughout an organisation, certain test must be done. The tests include determining the influence of expertise and experience of the person carrying out the inspections. The result of this study is an inspection process for 3kV DC traction substations that can be used to obtain a good idea of the condition of the system in order to make maintenance decisions that will improve the reliability of the system. / Prof. J.H.C. Pretorius Prof. W.A. Cronje