This thesis focuses on the development of a novel polymer based housing for power thyristor devices typically used in long distance high voltage direct current (HVDC) transmission. Power thyristor devices used in HVDC power conversion stations are typically packaged in a hermetically sealed ceramic housing and have demonstrated an excellent history of reliability and performance. However, to avoid increasing the number of thyristors in future higher powered HVDC schemes thyristors having higher power ratings at 8.5 kV and sizes at 125 mm and 150 mm diameters are sought for implementation to achieve higher transmission ratings of, for example, 4000 A at +/- 800 kV. The main disadvantages of such large ceramic-based packages are higher processing cost and weight whilst robustness is also a concern. To overcome these issues, replacing the current ceramic housing with a polymeric material has been investigated in this project. The advantages it is anticipated such packages will provide include lower cost, less weight, robustness, recyclability, etc. However, some challenges it will also offer are: non-hermeticity i.e. polymers are moisture and gas permeable, potentially more complex manufacturing routes, and different electrical, mechanical and thermal properties compared to ceramic materials. The work presented in this thesis was part of a larger project where these challenges have been addressed by developing and testing a prototype polymeric thyristor housing. The prototype is aimed at demonstrating that polymer packages can deliver performance and reliability comparable to, if not better than, current ceramic packages. In this thesis, it is the package development and reliability related studies that are discussed. Because the housings will experience severe electrical stresses and various thermal excursions during their service life, the electrical and thermo-mechanical behaviour of the polymer housing was studied using finite element analysis to gain an understanding of the effects of various design variables and materials properties on performance and the tradeoffs between performance and manufacturability. From these modelling studies, design guidelines have been established for the future development of polymer housings. On the other hand, to identify the physics-of-failure of the prototype that was manufactured as part of the project, accelerated life tests were performed to study its reliability. The knowledge gained from the polymer prototype development was then applied to the design of a larger 125 mm diameter housing using the Taguchi method of experimental design.

The use and application of 4 Dimensional Computer Aided Design (4D CAD) is growing within the construction industry. 4D approaches have been the focus of many research efforts within the last decade and several commercial tools now exist for the creation of construction simulations using 4D approaches. However, there are several key limitations to the current approaches. For example, 4D models are normally developed after the initial planning of a project has taken place using more traditional techniques such as Critical Path Method (CPM). Furthermore, mainstream methodologies for planning are based on individual facets of the construction process developed by discrete contractors or sub-contractors. Any 4D models generated from these data are often used to verify work flows and identify problems that may arise, either in terms of work methods or sequencing issues. Subsequently, it is perceived that current 4D CAD approaches provide a planning review mechanism rather than a platform for a novel integrated approach to construction planning. The work undertaken in this study seeks to address these issues through the application of a distributed virtual reality (VR) environment for collaborative 4D based construction planning. The key advances lie in catering for geographically dispersed planning by discrete construction teams. By leveraging networked 4D-VR based technologies, multidisciplinary planners, in different places, can be connected to collaboratively perform planning and create an integrated and robust construction schedule leading to a complete 4D CAD simulation. Establishing such a complex environment faces both technological and social challenges. Technological challenges arise from the integration of traditional and recent 4D approaches for construction planning with an ad hoc application platform of VR linked through networked computing. Social challenges arise from social dynamics and human behaviours when utilizing VR-based applications for collaborative work. An appropriate 4D-based planning method in a networked VR based environment is the key to gaining a technical advancement and this approach to distributed collaborative planning tends to promote computer-supported collaborative work (CSCW). Subsequently, probing suitable CSCW design and user interface/interaction (UI) design are imperative for solutions to achieve successful applicability. Based on the foregoing, this study developed a novel robust 4D planning approach for networked construction planning. The new method of interactive definition was devised through theoretical analysis of human-computer interaction (HCI) studies, a comparison of existing 4D CAD creation, and 3D model based construction planning. It was created to support not only individual planners’ work but multidisciplinary planners’ collaboration, and lead to interactive and dynamic development of a 4D simulation. From a social perspective, the method clarified and highlighted relevant CSCW design to enhance collaboration. Applying this rationale, the study specified and implemented a distributed groupware solution for collaborative 4D construction planning. Based on a developed system architecture, application mode and dataflow, as well as a real-time data exchange protocol, a prototype system entitled ‘4DX’ was implemented which provides a platform for distributed multidisciplinary planners to perform real-time collaborative 4D construction planning. The implemented toolkit targeted a semi-immersive VR platform for enhanced usability with compatibility of desktop VR. For the purpose of obtaining optimal UI design of this kind of VR solution, the research implemented a new user-centred design (UCD) framework of Taguchi-Compliant User-Centred Design (TC-UCD) by adapting and adopting the Taguchi philosophy and current UCD framework. As a result, a series of UIs of the VR-based solution for multifactor usability evaluation and optimization were developed leading to a VR-based solution with optimal UIs. The final distributed VR solution was validated in a truly geographically dispersed condition. Findings from the verification testing, the validation, and the feedback from construction professionals proved positive in addition to providing constructive suggestions to further reinforce the applicability of the approach in the future.

Submitted by Marlucy Farias Medeiros (marlucy.farias@unipampa.edu.br) on 2018-05-11T18:52:52Z No. of bitstreams: 1 Daniel_Lemes - 2018.pdf: 18189235 bytes, checksum: 1ee5df4451f15272b5fcd3e07ef614e8 (MD5) / Approved for entry into archive by Dayse Pestana (dayse.pestana@unipampa.edu.br) on 2018-05-14T12:00:34Z (GMT) No. of bitstreams: 1 Daniel_Lemes - 2018.pdf: 18189235 bytes, checksum: 1ee5df4451f15272b5fcd3e07ef614e8 (MD5) / Made available in DSpace on 2018-05-14T12:00:34Z (GMT). No. of bitstreams: 1 Daniel_Lemes - 2018.pdf: 18189235 bytes, checksum: 1ee5df4451f15272b5fcd3e07ef614e8 (MD5) Previous issue date: 2018-04-05 / The main goal of this work was to develop a MATLAB-based co de capable of finding the optimum values for amplitudes, phases and spacings of a non-uniformly spaced linear antenna array for a specified purpose. This tool allowed investigating the influence of the relative spacings between the elements of an antenna array in its radiation pattern. Two optimization methods were implemented: PSO (Particle swarm optimization), which is an evolutionary heuristic based on the social interaction and movement of swarms, and Taguchi’s method, which is based on orthogonal arrays to reduce the number of experiments needed to find the optimum value of a given variable. Different optimization goals were investigated, so that a comparison between these techniques has been done. The developed co de was applied to solve two practical problems. In the first one, a dual-band antenna array for base stations of mobile communication systems was modeled and its amplitudes, phases and spacings were optimized. By doing so, it was possible to mitigate the granting lobes that app eared in the pattern in the higher band, because the relative spacings between the elements could not be smaller than λ0. The pattern of this array was also shaped following a squared cosecant contour, in order to illuminate a pico-cell with uniform power. The results of the optimizations in both bands were validated using the commercial software Ansys HFSS and a study about the influence of the mutual coupling in the pattern was done. The second practical problem was to design an antenna array with beamshaping. By using the proposed code, it was possible to reduce the number of array elements from seven to four comparing to an uniformly spaced array. The optimization was split into two parts in order to mitigate the influence of the mutual coupling. A passive feeder for the optimized array was designed and a prototype was manufactured. The results were validated using HFSS and by measurements. The complete development of the array and of the feeder are detailed in this work. Finally, the design of a transmitter for adaptive beamshaping is described. The architecture nis capable to change the phase and power level of the signal, hence allowing to deliver the weights optimized by the proposed code to the antenna array. A modular concept was chosen in order to increase the flexibility of the transmitter. The device translates the input frequency from 500 MHz to 7 GHz, in order to deliver the weights to the antenna array. Eight transmitters were assembled and they were coupled to the antenna array in order to test their functionality. The patterns were measured in an anechoic chamber. All measured results of the transmitter are presented. / O principal objetivo deste trabalho foi desenvolver uma ferramenta computacional em MATLAB capaz de otimizar as fases, as amplitudes e os espaçamentos de uma rede de antenas, a fim de satisfazer um determinado objetivo. De posse dessa ferramenta, foi possível analisar a influência do espaçamento relativo entre os elementos de uma rede no diagrama da mesma. Dois métodos de otimização foram implementados: PSO (Particle Swarm Opmitization), baseado na interação social e no movimento de um enxame, e o método de Taguchi, que utiliza matrizes ortogonais para diminuir o número de testes necessários para otimizar uma variável. Diferentes cenários foram analisados de forma a permitir uma comparação entre os dois métodos. O código desenvolvido foi aplicado a dois problemas práticos. No primeiro deles, uma rede de antenas dupla-faixa para emprego em estações rádio base de sistemas de comunicações móveis foi modelada e suas amplitudes, fases e espaçamentos foram otimizados. Como na banda mais alta o espaçamento entre os elementos não podia ser menor que λ0., fez-se necessário otimizar os espaçamentos para controle dos grating lobes. O diagrama dessa rede foi também conformado seguindo um contorno em cossecante ao quadrado, para iluminar uma certa região com potência uniforme. Os resultados de todas as otimizações em ambas bandas foram validados usando o software Ansys HFSS e um estudo sobre a influência do acoplamento mútuo foi feito. O segundo caso consistiu na otimização de uma rede de antenas com conformação de feixe. Foi possível diminuir o número de elementos de sete para quatro em comparação a uma rede com elementos uniformemente espaçados. A otimização foi dividida em duas partes para compensar o efeito do acoplamento mútuo. Para a rede otimizada, um sistema alimentador passivo foi desenvolvido e um protótipo foi fabricado. Os resultados foram validados com simulações no software comercial Ansys HFSS e, também, por medições. Todo o projeto da rede e do alimentador é detalhado neste trabalho. Finalmente, o desenvolvimento de um circuito transmissor para beamshaping adaptativo ´e detalhado. Tal sistema é composto por um defasador e um amplificador de ganho variável, com os quais é possível inserir as amplitudes e fases, otimizadas pelo código proposto, em uma rede de antenas. Desenvolveu-se um transmissor modular, a fim de aumentar a flexibilidade do sistema. A frequência de entrada do transmissor é de 500 MHz, que é transladada para 7 GHz antes de ser entregue à rede de antenas. Foram fabricados oito transmissores, os quais foram acoplados a uma rede de antenas para testar suas funcionalidades. Os diagramas de irradiação foram medidos em câmera anecóica. Todo o desenvolvimento e medições de cada componente do transmissor são também mostrados neste trabalho.

Este modelo contempla o cenário em que a sequência de frações não-conformes no decorrer de um ciclo do processo de produção aumenta gradativamente (situação comum, por exemplo, quando o desgaste de um equipamento é gradual), diferentemente dos modelos de Taguchi, Nayebpour e Woodall e Nandi e Sreehari (1997), que acomodam sequências de frações não-conformes assumindo no máximo três valores, e de Nandi e Sreehari (1999) e Trindade, Ho e Quinino (2007) que contemplam funções de degradação mais simples. O desenvolvimento é baseado nos trabalhos de Ferguson e Antoniak para o cálculo da distribuição a posteriori de uma medida P desconhecida, associada a uma função de distribuição F desconhecida que representa a sequência de frações não-conformes ao longo de um ciclo, supondo, a priori, mistura de Processos Dirichlet. A aplicação consiste na estimação da função de distribuição F e as estimativas de Bayes são analisadas através de alguns casos particulares / In this work, we propose an alternative model for Taguchi´s On-Line Quality-Monitoring Procedure for Attributes under a Bayesian nonparametric framework. This model may be applied to production processes the sequences of defective fractions during a cycle of which increase gradually (for example, when an equipment deteriorates little by little), differently from either Taguchi\'s, Nayebpour and Woodall\'s and Nandi and Sreehari\'s models that allow at most three values for the defective fraction or Nandi and Sreehari\'s and Trindade, Ho and Quinino\'s which take into account simple deterioration functions. The development is based on Ferguson\'s and Antoniak\'s papers to obtain a posteriori distribution for an unknown measure P, associated with an unknown distribution function F that represents the sequence of defective fractions, considering a prior mixture of Dirichlet Processes. The results are applied to the estimation of the distribution function F and the Bayes estimates are analised through some particular cases.

The physical properties of polymer quench bath directly affect the cooling rate of a quenched part. These properties include the type of quenchant, its temperature, concentration, and agitation level. These parameters must be controlled to optimize the quenching process in terms of alloy microstructure, properties and performance. Statistically designed experiments have been performed to investigate the effects of the process parameters (i.e. polymer concentration and agitation) on the heat transfer behavior of cast aluminum alloy A356 in aqueous solution of Aqua-Quench 260 using the CHTE quenching-agitation system. The experiments were designed using Taguchi technique and the experimental results were analyzed with Analysis of Variance (ANOVA) based on the average cooling rate. It is found that average cooling rate dramatically decreases with the increase in polymer concentration. Agitation only enhances the average cooling rate at low and medium concentration levels. From ANOVA analysis, the process parameter that affects the variation of average cooling rate most is the polymer concentration, its percentage contribution is 97%. The effects from agitation and the interaction between polymer concentration and tank agitation are insignificant. The mechanical properties of age-hardenable Al-Si-Mg alloys depend on the rate at which the alloy is cooled after the solutionizing heat treatment. A model based on the transformation kinetics is needed for the design engineer to quantify the effects of quenching rates on the as-aged properties. Quench Factor analysis was developed by Staley to describe the relationship between the cooling rate and the mechanical properties of an age-hardenable alloy. This method has been previously used to successfully predict yield strength, hardness of wrought aluminum alloys. However, the Quench Factor data for aluminum castings are still rare in the literature. In this study, the Jominy End Quench method was used to experimentally collect the time-temperature and hardness data as the inputs for Quench Factor modeling. Multiple linear regression analysis was performed on the experimental data to estimate the kinetic parameters during quenching. Time-Temperature-Property curves of cast aluminum alloy A356 were generated using the estimated kinetic parameters. Experimental verification was performed on a L5 lost foam cast engine head. The predicted hardness agreed well with that experimentally measured.

Este modelo contempla o cenário em que a sequência de frações não-conformes no decorrer de um ciclo do processo de produção aumenta gradativamente (situação comum, por exemplo, quando o desgaste de um equipamento é gradual), diferentemente dos modelos de Taguchi, Nayebpour e Woodall e Nandi e Sreehari (1997), que acomodam sequências de frações não-conformes assumindo no máximo três valores, e de Nandi e Sreehari (1999) e Trindade, Ho e Quinino (2007) que contemplam funções de degradação mais simples. O desenvolvimento é baseado nos trabalhos de Ferguson e Antoniak para o cálculo da distribuição a posteriori de uma medida P desconhecida, associada a uma função de distribuição F desconhecida que representa a sequência de frações não-conformes ao longo de um ciclo, supondo, a priori, mistura de Processos Dirichlet. A aplicação consiste na estimação da função de distribuição F e as estimativas de Bayes são analisadas através de alguns casos particulares / In this work, we propose an alternative model for Taguchi´s On-Line Quality-Monitoring Procedure for Attributes under a Bayesian nonparametric framework. This model may be applied to production processes the sequences of defective fractions during a cycle of which increase gradually (for example, when an equipment deteriorates little by little), differently from either Taguchi\'s, Nayebpour and Woodall\'s and Nandi and Sreehari\'s models that allow at most three values for the defective fraction or Nandi and Sreehari\'s and Trindade, Ho and Quinino\'s which take into account simple deterioration functions. The development is based on Ferguson\'s and Antoniak\'s papers to obtain a posteriori distribution for an unknown measure P, associated with an unknown distribution function F that represents the sequence of defective fractions, considering a prior mixture of Dirichlet Processes. The results are applied to the estimation of the distribution function F and the Bayes estimates are analised through some particular cases.

近年來，隨著消費意識的提升，食品業者正面臨最嚴格的考驗，品質 產 生變異，將會反應在銷售量上，嚴重影響企業的經營。而目前台灣食品 造業者，有許多廠家仍停留在經驗掛帥、老式的檢驗品質階段，對於源流 瑊z的觀念仍不甚了解，致使品質提昇的效率不盡理想。有鑑於此，本研 究B用田口玄一博士生產線外品質工程理念架構，靈活搭配各種工具（如 系統洈k、直交表），以使田口方法更臻完善。同時利用S/N比（signal- to-Noes Ratio）變異數分析兩種方法進行資料解析，提供食品製造業者 最佳生ㄡ捰X。最後，乃以本人所親自參與之食品製造業品質改善研究實 驗為例，憭什ㄟ筆嗾膋熊痕G報告外，另詳述記載寶貴的實驗經歷，可進 一步提供相鶻t商作為改善品質的借鏡。

This thesis illustrates analysis of the influence of the non-machining processes on product quality by experimental design and statistical analysis. For the analysis objective / dishwasher production in Arcelik Dishwasher plant is examined. Sheet metal forming processes of dishwasher production constitutes the greatest portion of production cost and using the Pareto analysis technique / four pieces among twenty six pieces are determined to be investigated. These four pieces are the U Sheet, L Sheet, Inner Door and Side Panel of the dishwasher. By the help of the flow diagrams production process of the determined pieces are defined. Brainstorming technique and cause&amp / effect diagrams are used to determine which non-machining process parameters can cause pieces to be scrapped. These parameters are used as control factors in experimental design. Taguchi&amp / #8217 / s L16(215) orthogonal array, Taguchi&amp / #8217 / s L16(215) orthogonal array using S/N transformation and 28-4 fractional factorial design are used on purpose. With repetitions and confirmation experiments the effective parameters are determined and optimum level of these parameters are defined for the improvements on scrap quantity and quality of production.

Classification approaches are used in many areas in order to identify or estimate classes, which different observations belong to. The classification approach, Mahalanobis Taguchi System (MTS) is analyzed and further improved for multi-class classification problems under the scope of this thesis study. MTS tries to explore significant variables and classify a new observation based on its Mahalanobis distance (MD). In this study, first, sample size problems, which are encountered mostly in small data sets, and multicollinearity problems, which constitute some limitations of MTS, are analyzed and a re-sampling approach is explored as a solution. Our re-sampling approach, which only works for data sets with two classes, is a combination of over-sampling and under-sampling. Over-sampling is based on SMOTE, which generates the synthetic observations between the nearest neighbors of observations in the minority class. In addition, MTS models are used to test the performance of several re-sampling parameters, for which the most appropriate values are sought specific to each case. In the second part, multi-class classification methods with MTS are developed. An algorithm, namely Feature Weighted Multi-class MTS-I (FWMMTS-I), is inspired by the descent feature weighted MD. It relaxes adding up of the MDs for variables equally. This provides representations of noisy variables with weights close to zero so that they do not mask the other variables. As a second multi-class classification algorithm, the original MTS method is extended to multi-class problems, which is called Multi-class MTS (MMTS). In addition, a comparable approach to that of Su and Hsiao (2009), which also considers weights of variables, is studied with a modification in MD calculation. It is named as Feature Weighted Multi-class MTS-II (FWMMTS-II). The methods are compared on eight different multi-class data sets using a 5-fold stratified cross validation approach. Results show that FWMMTS-I is as accurate as MMTS, and they are better than FWMMTS-II. Interestingly, the Mahalanobis Distance Classifier (MDC) using all the variables directly in the classification model has performed equally well on the studied data sets.

This thesis illustrates parameter optimization of compressive strength, flexural strength and impact resistance of steel fiber reinforced high strength concrete (SFRHSC) by statistical design and analysis of experiments. Among several factors affecting the compressive strength, flexural strength and impact resistance of SFRHSC, five parameters that maximize all of the responses have been chosen as the most important ones as age of testing, binder type, binder amount, curing type and steel fiber volume fraction. Taguchi and regression analysis techniques have been used to evaluate L27(313) Taguchi&amp / #65533 / s orthogonal array and 3421 full factorial experimental design results. Signal to noise ratio transformation and ANOVA have been applied to the results of experiments in Taguchi analysis. Response surface methodology has been employed to optimize the best regression model selected for all the three responses. In this study Charpy Impact Test, which is a different kind of impact test, have been applied to SFRHSC for the first time. The mean of compressive strength, flexural strength and impact resistance have been observed as around 125 MPa, 14.5 MPa and 9.5 kgf.m respectively which are very close to the desired values. Moreover, this study is unique in the sense that the derived models enable the identification of underlying primary factors and their interactions that influence the modeled responses of steel fiber reinforced high strength concrete.