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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.
31

On the statistical analysis of functional data arising from designed experiments

Sirski, Monica 10 April 2012 (has links)
We investigate various methods for testing whether two groups of curves are statistically significantly different, with the motivation to apply the techniques to the analysis of data arising from designed experiments. We propose a set of tests based on pairwise differences between individual curves. Our objective is to compare the power and robustness of a variety of tests, including a collection of permutation tests, a test based on the functional principal components scores, the adaptive Neyman test and the functional F test. We illustrate the application of these tests in the context of a designed 2^4 factorial experiment with a case study using data provided by NASA. We apply the methods for comparing curves to this factorial data by dividing the data into two groups by each effect (A, B, . . . , ABCD) in turn. We carry out a large simulation study investigating the power of the tests in detecting contamination, location, and shift effects on unimodal and monotone curves. We conclude that the permutation test using the mean of the pairwise differences in L1 norm has the best overall power performance and is a robust test statistic applicable in a wide variety of situations. The advantage of using a permutation test is that it is an exact, distribution-free test that performs well overall when applied to functional data. This test may be extended to more than two groups by constructing test statistics based on averages of pairwise differences between curves from the different groups and, as such, is an important building-block for larger experiments and more complex designs.
32

BIODIESEL PRODUCTION USING SUPPORTED 12-TUNGSTOPHOSPHORIC ACID AS SOLID ACID CATALYSTS

2014 December 1900 (has links)
Biodiesel has achieved worldwide recognition for many years due to its renewability, lubricating property, and environmental benefits. The abstract represents a summary of all the chapters of the thesis. The research chapters are defined as research phases in the abstract. The thesis starts with an introduction followed by literature review. In the literature review, all the necessary data were collected reviewing the literature. Then an artificial neural network model (ANN) was built based on the published research data to capture the general trends or to make predictions. Both catalyst properties and reaction conditions were trended and predicted using the network model. The review study revealed that esterification and transesterification required catalysts with slightly different properties. In the first phase of the study, biodiesel production using 12-Tungstophosphric acid (TPA) supported on SBA-15 as a solid acid catalyst was studied. In this phase of the study, a large number of 0-35% TPA on SBA-15 catalysts were synthesized by impregnation method and the effects of various operating conditions such as–catalyst wt.% and methanol to oil molar ratio on the transesterification of model feedstock Triolein were studied. A 25% TPA loading was found to be the optimum. A 4.15 wt.% catalysts (based on Triolein) and 39:1 methanol to Triolein molar ratio was found to be the optimum reaction parameter combination, when the reaction temperature was kept fixed at 200C, stirring speed of 600 rpm and 10 h reaction time. The biodiesel yield obtained using this condition was 97.2%. In the second phase of the study, a 12-Tungstophosphoric acid (TPA) was supported by using organic functional group (i.e. 3-aminopropyltriethoxysilane (APTES)) and was incorporated into the SBA-15 structure. A 45 wt.% TPA incorporated SBA-15 produced an ester with biodiesel yield of 97.3 wt.%, when 3 wt.% catalyst (based on the green seed canola (GSC) oil) and 25.8:1 methanol GSC oil molar ratio were used at 2000C for reaction time of 6.2 h. In the third phase, process sustainability (i.e. process economics, process safety, energy efficiency, environmental impact assessment) studies were conducted based on the results obtained in phase three. Based on the study, it was concluded that heterogeneous acid catalyzed process had higher profitability as compared to the homogeneous acid catalyzed process. Additionally, it was obtained that heterogeneous acid catalyzed process was safe, more energy efficient and more environment friendly than homogenous process. In the fourth phase, the catalytic activity of Tungsten oxide (WO3) and TPA supported (by impregnation) on H-Y, H-β and H-ZSM-5 zeolite catalysts were tested for biodiesel production from Green Seed Canola (GSC) oil. In this phase of the study, TPA/H-Y and TPA/H- zeolite were proved to be effective catalysts for esterification and transesterification, respectively. A 55% TPA/H- showed balanced catalytic activity for both esterification and transesterification. It yielded 99.3 wt.% ester, when 3.3 wt.% catalyst (based on GSC oil) and 21.3:1 methanol to GSC oil molar ratio were used at 200C, reaction pressure of 4.14 MPa and reaction time of 6.5 h. Additionally, this catalyst (55% TPA/H-) was experimented for etherification of pure glycerol, and maximum conversion of glycerol (100%) was achieved in 5 h at 120C, 1 MPa, 1:5 molar ratio (glycerol: (tert-butanol) TBA), 2.5% (w/v) catalyst loading. Later, these conditions were used to produce glycerol ether successfully from the glycerol derived after transesterification of green seed canola oil. A mixture of GSC derived biodiesel, and glycerol ether was defined as biofuels. In the fifth phase, catalytic activity of H-Y supported TPA (using different impregnation methods) was studied in details further for esterification of free fatty acid (FFA) of GSC oil. From the optimization study, 97.2% FFA (present in the GSC oil) conversion was achieved using 13.3 wt.% catalyst, 26:1 methanol to FFA molar ratio at 120°C reaction temperature and 7.5 h of reaction time.In the sixth- and final phase, techno-economic and ecological impacts were compared between biodiesel and combined biofuel production processes based on the results obtained in phase four. Based on the study, it was concluded that, biodiesel production process had higher profitability as compared to that for combined biofuel production process. Additionally, biodiesel production process was more energy efficient than combined biofuel production process. However, combined biofuel production process was more environment-friendly as compared to that for biodiesel production process.
33

Determinação da influência de parâmetros de processo de forjamento a quente utilizando DOE (projeto de experimentos)

Farias, Marcelo Fernandes January 2017 (has links)
Atualmente o Projeto de Experimentos (DOE) vem sendo largamente utilizado para determinar os fatores de projetos e processos mais significativos afetando uma variável resposta e para estabelecer modelos empíricos entre os fatores, entretanto este método ainda é pouco utilizado e processo de forjamento a quente. O presente trabalho analisa a influência individual e cumulativa de alguns parâmetros controláveis de um processo de forjamento a quente em matriz fechada na força de prensagem necessária para sua realização. Esta análise foi realizada utilizando a técnica de Projeto de Experimentos (DOE). Para a determinação da influência dos parâmetros de processo selecionados na variável resposta do Projeto de Experimentos (DOE), uma série de ensaios variando o lubrificante utilizado, o diâmetro da geratriz e a temperatura de forjamento foram realizados. A variável resposta para o experimento foi definida como a força de prensagem exigida do equipamento para a realização do forjamento. Para este trabalho foi utilizado o material ABNT 4140 fornecido em barras trefiladas de 28,6mm (1.1/8″) posteriormente forjado a quente em matriz fechada. Os resultados mostraram que o fator que mais influencia na força de prensagem para a situação ensaiada é o lubrificante. Os demais fatores, mesmo combinados, não apresentaram uma influência significativa na variável resposta. O presente estudo demonstra que é possível a utilização de técnicas de ajuste e definição de parâmetros de processo de forjamento a quente de maneira confiável e sem a necesside da aplicação dos complexos programas de simulação computacional e os métodos de tentativa e erro ainda presentes na indústria. Finalmente este trabalho reforça a versatilidade do Projeto de Experimentos (DOE) ainda pouco aplicado em processos de forjamento. / Nowadays the Design of Experiments (DOE) has been widely used to determine the most significant project and process factors affecting a response variable and to establish empirical models among the factors, although this method is still little used and the process of hot forging. This work analyzes the individual and cumulative influence of some controllable parameters in a closed die hot forging process in the pressing force required for its realization. This analysis was performed using a Design of Experiments (DOE) method. To determine the influence of variable factors selected in response Design of Experiments (DOE), a several tests varying the lubricant, the diameter of the billet and the forging temperature was performed. The response variable for the experiment was defined as pressing force. For this study, it was used the ABNT 4140 steel provided in drawn bars of 28,6mm (1 1/8 ″). The fator that had more influence over the pressing force was the lubricant. Other factors, whether or not combined, did not show a significant influence on the response variable. This study demonstrates that it is possible use techniques to set hot forging process parameters reliably and without necesside the application of complex computer simulation programs or the trial and error system. Finally, this work reinforces the versatility of Design of Experiments (DOE) wich is still little used in forging processes.
34

Análise do efeito interativo de falhas em processos de manufatura através de projeto de experimentos simulados

Leal, Fabiano [UNESP] 19 December 2008 (has links) (PDF)
Made available in DSpace on 2014-06-11T19:35:40Z (GMT). No. of bitstreams: 0 Previous issue date: 2008-12-19Bitstream added on 2014-06-13T19:25:04Z : No. of bitstreams: 1 leal_f_dr_guara.pdf: 1508454 bytes, checksum: 6fb895a4a4112ad5c2402cf1919b9b45 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Em vários problemas relacionados à análise de falhas em processos de manufatura, os efeitos das falhas são analisados de forma independente. Porém, em alguns sistemas, as falhas podem apresentar um efeito de interação. Se este efeito interativo for ignorado, o risco da falha também será subestimado. Deste modo, este trabalho objetivou analisar o efeito interativo de falhas em processos através de projeto de experimentos simulados. Para esta análise, realizou-se uma modelagem conceitual do processo e das falhas, através da técnica desenvolvida e nomeada de IDEF-SIM. Os experimentos simulados foram delineados, a fim de se verificar os efeitos principais dos modos de falha e de suas interações. Dois objetos de estudo do setor de autopeças foram escolhidos para esta pesquisa. Concluiu-se o trabalho com a hierarquização dos modos de falha e interações de acordo com o impacto na produção. Esta hierarquização foi apresentada segundo os efeitos locais e globais do modo de falha, através da apresentação de seis cenários. Desta forma, definem-se como principais aspectos originais deste trabalho: a determinação do efeito interativo de falhas em processos através do projeto de experimentos simulados e a modelagem conceitual de processos e falhas para a simulação, através de uma técnica proposta, o IDEF-SIM. / In several problems related to failures analysis in manufacturing processes, their effects are analyzed in an independent way. Even so, in some systems, the failures can present an interactive effect. If this interactive effect is ignored, the risk of the failure will also be underestimated. In this way, this work aims to analyze the failures interactive effect in processes through design of simulated experiments. For this analysis, a conceptual modeling was used to model processes and failures, through a proposed technique named IDEF-SIM. The simulated experiments were designed in order to verify the main effects of the failures modes and their interactions. Two studies from the automotive industry were chosen for this research. This work was concluded by ranking the failures modes and interactions, in accordance with the production impact. This hierarchization was presented according to the local and global effects of the failures modes by means of six sceneries. In this manner, the main original aspects of this work is defined as the determination of failures interactive effect in processes through the design of simulated experiments and the conceptual modeling for simulation of processes and failures through the proposed IDEF-SIM technique.
35

Determinação da influência de parâmetros de processo de forjamento a quente utilizando DOE (projeto de experimentos)

Farias, Marcelo Fernandes January 2017 (has links)
Atualmente o Projeto de Experimentos (DOE) vem sendo largamente utilizado para determinar os fatores de projetos e processos mais significativos afetando uma variável resposta e para estabelecer modelos empíricos entre os fatores, entretanto este método ainda é pouco utilizado e processo de forjamento a quente. O presente trabalho analisa a influência individual e cumulativa de alguns parâmetros controláveis de um processo de forjamento a quente em matriz fechada na força de prensagem necessária para sua realização. Esta análise foi realizada utilizando a técnica de Projeto de Experimentos (DOE). Para a determinação da influência dos parâmetros de processo selecionados na variável resposta do Projeto de Experimentos (DOE), uma série de ensaios variando o lubrificante utilizado, o diâmetro da geratriz e a temperatura de forjamento foram realizados. A variável resposta para o experimento foi definida como a força de prensagem exigida do equipamento para a realização do forjamento. Para este trabalho foi utilizado o material ABNT 4140 fornecido em barras trefiladas de 28,6mm (1.1/8″) posteriormente forjado a quente em matriz fechada. Os resultados mostraram que o fator que mais influencia na força de prensagem para a situação ensaiada é o lubrificante. Os demais fatores, mesmo combinados, não apresentaram uma influência significativa na variável resposta. O presente estudo demonstra que é possível a utilização de técnicas de ajuste e definição de parâmetros de processo de forjamento a quente de maneira confiável e sem a necesside da aplicação dos complexos programas de simulação computacional e os métodos de tentativa e erro ainda presentes na indústria. Finalmente este trabalho reforça a versatilidade do Projeto de Experimentos (DOE) ainda pouco aplicado em processos de forjamento. / Nowadays the Design of Experiments (DOE) has been widely used to determine the most significant project and process factors affecting a response variable and to establish empirical models among the factors, although this method is still little used and the process of hot forging. This work analyzes the individual and cumulative influence of some controllable parameters in a closed die hot forging process in the pressing force required for its realization. This analysis was performed using a Design of Experiments (DOE) method. To determine the influence of variable factors selected in response Design of Experiments (DOE), a several tests varying the lubricant, the diameter of the billet and the forging temperature was performed. The response variable for the experiment was defined as pressing force. For this study, it was used the ABNT 4140 steel provided in drawn bars of 28,6mm (1 1/8 ″). The fator that had more influence over the pressing force was the lubricant. Other factors, whether or not combined, did not show a significant influence on the response variable. This study demonstrates that it is possible use techniques to set hot forging process parameters reliably and without necesside the application of complex computer simulation programs or the trial and error system. Finally, this work reinforces the versatility of Design of Experiments (DOE) wich is still little used in forging processes.
36

Procedimento para o desenvolvimento de tecidos de malha a partir de planejamento de experimentos / Proceeding to develop knitted frabics with design of experiments

Sanches, Regina Aparecida 31 July 2006 (has links)
Orientador: Franco Giuseppe Dedini / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica / Made available in DSpace on 2018-08-08T23:58:43Z (GMT). No. of bitstreams: 1 Sanches_ReginaAparecida_D.pdf: 6482630 bytes, checksum: 884aa0c09cfb0b504f3db72a091fa6ca (MD5) Previous issue date: 2006 / Resumo: As características que determinam a qualidade de um produto de vestuário começam com a seleção das matérias primas, fibras, fios e tecidos, passando pelas fases de criação, desenvolvimento, confecção e acabamento. O objetivo deste trabalho é propor um procedimento para a seleção de matéria prima que será utilizada na fabricação de artigos para vestuário. Foram escolhidos fios de algodão, visando à produção de artigos confortáveis e fios de poliamida e de poliéster texturados ao ar, que possibilitam a produção de artigos com aspecto e toque de fibra natural. Para cada matéria prima, foi montado um planejamento fatorial 22, com o objetivo de identificar os fatores de controle da máquina circular que irão influenciar nas características das malhas. Utilizando a programação linear foi feita a otimização dos parâmetros de controle da máquina e produzidos tecidos de malha com mesmas características. A seleção da matéria prima ideal para a produção dos artigos foi feita utilizando o AHP ¿ Método de Análise Hierárquica / Abstract: The characteristics which determine the quality of a clothing product begin with the choice of raw materials, fibers, yarns and fabrics passing through the creation, development, apparel industry and finishing. The purpose of this work is to propose a proceeding for helping the development of textile products. Cotton yarns were chosen aiming at the production of comfortable goods and polyamide and polyester air textured yarns, which enable the production of goods with natural fiber look and hand. For each raw material, it was provided a 22 factorial design, aiming at identifying the control factors of the circular machine which influence the knitted fabrics. Using the linear programming, the optimization of the machine control parameters was done and knitted fabrics, with the same characteristics, were produced. The choice of the ideal raw material for the production of the goods has been done using the AHP ¿ Analytic Hierarchy Process / Doutorado / Mecanica dos Sólidos e Projeto Mecanico / Doutor em Engenharia Mecânica
37

Impact of stiffness and damping capacity using two different rubbers on friction coefficient and noise levels of brake materials

Punna, Harshitha 01 May 2020 (has links)
Friction contact with both external and internal environments can significantly influence its efficiency, which could cause friction instabilities, vibration, and noise. Focusing on the effects that troubles brake pad, rotor, and friction-induced NVH, the main motivation for this study is to understand its drawbacks for some extent in a braking system. By proper study on applied statistics, an experimental design is planned. The design has friction tests that are performed by scaling down real test properties used in dynamometer to scaled-down properties in a subscale tester by using scaling law of physics. The test has two different types of rubbers with different humidity conditions with respect to two different brake pads in a small-scale tester, the Universal Mechanical Tester (UMT). This friction experiment helps in determining how different rubbers impact its stiffness on the coefficient of friction and noise levels, also to evaluate which scenario has the better damping capacity. The effect on the coefficient of friction and noise levels with and without rubbers is also compared. The results are subjected to the Design of Experiments analyses test know the statistical relationship between factors affecting the process and output of that process at different controllable variables namely humidity and temperature.
38

Design of Experiments (DOE) for Product and Process Improvements: A Phenolic Syntan Case Study

Verlaan, Eric, Hendriksen, Wouter, Meulenbroek, Rob, du Prie, Devlin 26 June 2019 (has links)
Content: For sustainable developments the chemical industry is continuously looking for technical innovations with wide potential implications. The Design of Experiments (DOE) approach has been proven to be a powerful tool in determining the relationship between factors affecting certain output variables. This is done to establish a 'cause and effect' relationship and eventually realize output optimization. In order to evaluate whether DOE can be implemented for improving our products and processes, a case study, focusing on the synthesis and production of traditional phenolic syntans was carried out within our R&D department. Although we can influence properties by application, the effect a retanning agent has on leather originates to a large extent from the chemistry involved. To understand interactions and the possibilities of targeted improvements of the production process, a DOE factorial design approach was used to identify the control parameters and their interactions in our phenolic syntan recipes that influence the various properties and effects. Instead of trial-and-error or one-factor-at-a-time practices, DOE made it possible to limit the number of lab experiments to one third (1/3) of the amount needed for completing our study. As a result, a much deeper and more consistent understanding of the building blocks’ interactions and how these influence the chemical process of phenolic syntan synthesis has been gained. This includes the amount of different building blocks, their molar ratios as well as process conditions. Aiming at achieving optimal efficiency for various projects, right now we are looking at possibilities in implementing DOE within Smit & zoon. Take-Away: The Design of Experiments (DOE) approach is a powerful tool in realizing process and product improvements. DOE factorial design can be used to identify control parameters and their interactions in a wide reage of (industrial) applications. DOE has been proven to be efficient and effective in optimizing phenolic syntan recipes and production process.
39

Vývoj HPLC metody pro hodnocení čistoty a stability fesoterodinu za použití přístupu plánování experimentu / Development of HPLC method for evaluating the purity and stability of fesoterodine using a design of experiment approach

Erdeová, Karolína January 2017 (has links)
The aim of this diploma thesis was to develop and validate a high performance liquid chromatography (HPLC) method for purity and stability evaluation of fesoterodine. The HPLC method development was carried out using design of experiments (DOE), which allows to find optimal separation conditions within small number of experimental analysis. Design was done by using L18 linear model. Chromatographic system of the developed method consisted of a C8 stationary phase (SF) XBridge BEH - C8 (100 x 4.6 mm, 2.5 µm), a binary mobile phase (MF) consisting of 10mM borate buffer pH 9.2 and MeOH in various ratios according to the gradient program. Flow rate was 0.7 ml/min, column temperature 35 řC and a diode-array detector (DAD) was applied for the detection at 227 nm. Analysis time was 22 min. The optimized method was validated and the forced degradation study was performed. Studied effects were: the effect of elevated temperature (60 řC), humidity (10 and 75% relative humidity), acidic and basic conditions, oxidation and light. Peak purity of fesoterodine was evaluated for all experiments of forced degradation study. Additionally, the sensitivity of the active substance to hydrolysis was determined within the pH range of 2-10.
40

FINDING IMPORTANT FACTORS IN AN EFFECTS-BASED PLAN USING SEQUENTIAL BIFURCATION

Seyedamin, Arvand January 2012 (has links)
After the pilot phase of a simulation study, if the model contains many factors, then direct experimentation may need too much computer processing time, therefore the purpose of screening simulation experiments is to eliminate negligible or unimportant factors of a simulation model in order to concentrate the efforts upon a short list of important factors. For this matter the Sequential bifurcation procedure developed by Bettonvil and Kleijnen [3] is an efficient and effective screening method which can be used. In this study, the Sequential bifurcation screening method is used to determine the important factors of a simulation based decision support model designed by The Swedish Defense Research Agency (FOI) meant for testing operational plans. By using this simulation model, a decision maker is able to test a number of feasible plans against possible courses of events. The sequential bifurcation procedure was applied and sorted the most important factors involved in this simulation model based on their relative importance.

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