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Productivity and health of indigenous sheep breeds and crossbreds in the central Ethiopian highlands /Tibbo, Markos, January 2006 (has links) (PDF)
Diss. (sammanfattning) Uppsala : Sveriges lantbruksuniviversitet, 2006. / Härtill 7 uppsatser.
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Determining when time response curves differ in the presence of censorship /Lazar, Ann A. January 2008 (has links)
Thesis (Ph.D. in Biostatistics) -- University of Colorado Denver, 2008. / Typescript. Includes bibliographical references (leaves 53-56). Online version available via ProQuest Digital Dissertations.
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Applying goodness-of-fit techniques in testing time series Gaussianity and linearityJahan, Nusrat, January 2006 (has links)
Thesis (Ph.D.)--Mississippi State University. Department of Mathematics and Statistics. / Title from title screen. Includes bibliographical references.
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Statistical analyses of artificial waterpoints : their effect on the herbaceous and woody structure composition within the Kruger National Park /Goodall, Victoria Lucy. January 2006 (has links)
Thesis (M.Sc. (Statistics)) - Rhodes University, 2007. / A thesis submitted in partial fulfilment of the requirements for the degree of Master of Science.
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Semiconductor Yield Modeling Using Generalized Linear ModelsJanuary 2011 (has links)
abstract: Yield is a key process performance characteristic in the capital-intensive semiconductor fabrication process. In an industry where machines cost millions of dollars and cycle times are a number of months, predicting and optimizing yield are critical to process improvement, customer satisfaction, and financial success. Semiconductor yield modeling is essential to identifying processing issues, improving quality, and meeting customer demand in the industry. However, the complicated fabrication process, the massive amount of data collected, and the number of models available make yield modeling a complex and challenging task. This work presents modeling strategies to forecast yield using generalized linear models (GLMs) based on defect metrology data. The research is divided into three main parts. First, the data integration and aggregation necessary for model building are described, and GLMs are constructed for yield forecasting. This technique yields results at both the die and the wafer levels, outperforms existing models found in the literature based on prediction errors, and identifies significant factors that can drive process improvement. This method also allows the nested structure of the process to be considered in the model, improving predictive capabilities and violating fewer assumptions. To account for the random sampling typically used in fabrication, the work is extended by using generalized linear mixed models (GLMMs) and a larger dataset to show the differences between batch-specific and population-averaged models in this application and how they compare to GLMs. These results show some additional improvements in forecasting abilities under certain conditions and show the differences between the significant effects identified in the GLM and GLMM models. The effects of link functions and sample size are also examined at the die and wafer levels. The third part of this research describes a methodology for integrating classification and regression trees (CART) with GLMs. This technique uses the terminal nodes identified in the classification tree to add predictors to a GLM. This method enables the model to consider important interaction terms in a simpler way than with the GLM alone, and provides valuable insight into the fabrication process through the combination of the tree structure and the statistical analysis of the GLM. / Dissertation/Thesis / Ph.D. Industrial Engineering 2011
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Comportement mécanique de planchers diaphragmes en bois : semi-rigidité et résistance pour une situation sismique / Mechanical behavior of timber floor diaphragms : stiffness and strength under seismic situationFuentes, Sebastian 19 June 2013 (has links)
Pour les structures en bois comme pour les autres techniques de construction, les planchers jouent un rôle important dans le comportement global d’un bâtiment soumis à une sollicitation sismique. En plus de la reprise des efforts verticaux, ces planchers assurent le transfert des efforts horizontaux vers les murs de contreventement (fonction diaphragme). Pour cette fonction, le plancher peut être assimilé à une poutre courte disposée horizontalement et supportée par plusieurs appuis semi-rigides (murs de contreventement). En conséquence, la distribution des efforts sur les murs de contreventement est directement liée au rapport entre leurs raideurs et celle du plancher dans son plan.Les planchers en bois traditionnels sont généralement composés par une poutraison (des solives, des entretoises et des poutres de chaînage) et une surface plane composée d’une juxtaposition de panneaux. La connexion panneaux-poutraison est généralement réalisée par des clous. Le dimensionnement de ces planchers est souvent piloté par les charges verticales et les caractéristiques mécaniques dans le plan sont rarement contrôlées.Le comportement mécanique des planchers diaphragmes en bois est peu étudié dans la littérature. La présente thèse aborde ce comportement en s’appuyant sur trois approches : analytique, numérique (M.E.F.) et expérimentale. L’approche analytique s’inspire de celle utilisée par les codes de calcul sismique nord-américains. La modélisation numérique prend en compte la configuration géométrique réelle des diaphragmes ainsi que les effets non-linéaires matériels et géométriques. Deux types de modèles numériques sont proposés : « détaillé » et « simplifié ». Le modèle détaillé, utilisant des éléments de poutres et de coques, permet d’étudier la distribution des contraintes internes au sein du plancher. Le modèle simplifié, moins coûteux, s’appuie sur des éléments poutres et barres. Il permet de réaliser des analyses de sensibilité et il peut être utilisé dans des analyses de structures avec géométries complexes.Une campagne expérimentale est conduite sur des planchers en bois. Deux planchers (2,4x7,2m2), avec et sans entretoises, sont testés en flexion dans leur plan. Une instrumentation riche composée de capteurs de déplacement, d’inclinomètres et d’un système de mesure sans contact, sont utilisés pour suivre le comportement de ces planchers aux niveaux global et local. Les observations expérimentales montrent un comportement fortement non-linéaire avec une influence importante des entretoises sur la raideur et la résistance. La rupture des panneaux est due à la flexion à mi portée ou à la compression près des angles en contact. La comparaison avec les résultats expérimentaux a permis de valider les modèles numériques développés. Ces modèles révèlent une forte participation de la connexion panneaux-poutraison aux comportements mécaniques des planchers aux niveaux global et local.Le modèle numérique simplifié est utilisé pour mener une étude de sensibilité des planchers avec trémies. Ainsi, treize configurations de planchers sont analysées en vue d’identifier les positionnements les plus défavorables des trémies. Par ailleurs, l’application du modèle analytique montre qu’il représente correctement la phase linéaire du comportement des planchers qui est un paramètre utilisable dans les analyses à l’état limite de service. Les résultats numériques et expérimentaux obtenus constituent une bonne base pour étendre le domaine d’application du modèle analytique. / In timber structures as other, floors play an important role in the overall behaviour of a building subjected to seismic loading. In addition to the vertical forces, these floors transfer horizontal forces to the shear walls (diaphragm function). For this function, the floor can be considered as a short beam placed horizontally and supported by semi-rigid supports (shear walls). Therefore, the force distribution on the shear walls is directly related to the in-plane stiffness ratio between floors and shear walls.Traditional wooden floors are usually composed by joists framing (joist, struts, chords beams) and a surface made by juxtaposed panels. The panel-joist framing connection is usually made by nails. Size of the floors elements is often driven by the vertical loads, thus mechanical properties in the plane are rarely checked.The in-plane behaviour of timber floor is poorly studied in the literature. This thesis studies this behaviour using three approaches: analytical, numerical (FEM) and experimental. The analytical approach is based on that used in North American codes of seismic design. Numerical models take into account the actual geometry of the timber diaphragms and nonlinear effects (material and geometric). Two types of numerical models are proposed: "detailed" and "simplified". The detailed model, based on beams and shell elements, allows studying the distribution of internal stresses in the floor. The simplified model uses beams and bar elements. It allows carrying out sensitivity analysis and can be used to study complex geometries of floors.An experimental campaign is conducted on timber floors. Two floors (2,4 x7,2m2), in blocked or unblocked configuration, are tested in bending in their plane. Displacement transducers, inclinometers and a camera measuring system are used for monitoring the behaviour of floors at global and local levels. The experimental observations show a highly nonlinear behaviour with a significant influence of struts on the stiffness and strength. Panels failure due to bending and compression in the corners were observed. The comparison between experimental and numerical results allows validating the numerical models. These models show a significant participation of the panels-joist framing connection on the global and local mechanical behaviour of floors.The simplified model is used to conduct a sensitivity analysis of floors with hoppers. Thirteen floors configurations are analyzed to identify the most unfavourable configurations of hoppers position. Furthermore, the analytical model represents well the linear phase of floors behaviour. The numerical and experimental results obtained provide a good basis to expand the scope of the analytical model. / Tanto en las estructuras de madera como en otras técnicas de construcción, las losas juegan un importante rol en el comportamiento global de un edificio sometido a una solicitación sísmica. Además de las cargas verticales, las losas deben transmitir las cargas horizontales hacia los muros de corte (función diafragma). En esta función, la losa puede ser tratada como una viga corta puesta horizontalmente y apoyada sobre soportes semi-rígidos (muros de corte). En consecuencia, la distribución de fuerzas entre los distintos muros de corte es determinada por la relación de rigidez entre estos muros y la losa.Las losas tradicionales de madera son generalmente compuestas por un envigado (vigas transversales, canes o separadores, vigas periféricas) y una superficie construida con paneles yuxtapuestos. La conexión entre los paneles y el envigado es generalmente realizada con clavos. El dimensionamiento de estos elementos es habitualmente determinado por las cargas verticales, de esta manera las propiedades mecánicas en el plano de estas losas, son raramente controladas.El comportamiento mecánico de los diafragmas de madera ha sido poco estudiado en la literatura. Esta tesis aborda este comportamiento a partir de tres enfoques: analítico, numérico (Elementos Finitos) y experimental. El método analítico considerado se basa en las ecuaciones propuestas por los códigos de diseño sísmico norteamericanos. La modelización numérica tiene en cuenta la configuración geométrica real de las losas y los efectos no-lineares de origen material y geométrico. Dos tipos de modelos numéricos son propuestos: "detallado" y "simplificado". El modelo detallado, es construido a partir de elementos finitos de tipo vigas y planos. Este modelo es utilizado principalmente para estudiar la distribución de esfuerzos internos en las losas. El modelo simplificado, construido a partir de elementos de vigas y barras, es utilizado para conducir análisis de sensibilidad.Un estudio experimental sobre losas de madera es presentado. Dos losas (2,4 x7, 2m2) con y sin separadores son testeadas en flexión en su plano. Un sistema de instrumentación compuesto por transductores de desplazamiento, inclinómetros y videocámaras, fueron utilizados para monitorear el comportamiento global y local de las losas. Las observaciones experimentales muestran un comportamiento altamente no-lineal con una fuerte influencia de los separadores sobre la rigidez y resistencia de la estructura. Los modos de ruptura observados corresponden a la ruptura de paneles en flexión y a la compresión local debido a transmisión de esfuerzos por contacto. La comparación de resultados experimentales y numéricos permite validar los modelos propuestos. Estos modelos muestran una fuerte participación de la conexión paneles-envigado sobre el comportamiento mecánico global y local de las losas.El modelo numérico simplificado es utilizado para llevar a cabo un análisis de sensibilidad de losas con aberturas de escalera. Trece configuraciones de losas son analizadas para identificar la posición de abertura más desfavorable. Por otra parte, el modelo analítico representa correctamente el comportamiento de las losas en fase lineal. Los resultados numéricos y experimentales obtenidos proporcionan una buena base para ampliar el dominio de aplicación de este modelo analítico.
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Otimização de processos com respostas múltiplas e categóricasLucas, Cícero de Melo January 2007 (has links)
A presente dissertação aborda a otimização de processos industriais através da utilização de projeto de experimentos. Em experimentos planejados, variáveis de respostas são usualmente consideradas como normalmente distribuídas. No entanto, em algumas situações, tal suposição é violada; por exemplo, quando respostas expressam contagens, podendo assumir somente valores inteiros e não-negativos. Nesses casos, é mais provável que as respostas sigam uma distribuição de Poisson e, em sua modelagem, deve-se utilizar os modelos lineares generalizados (MLG), adequados para respostas da chamada família exponencial, à qual pertence a distribuição de Poisson. Se ainda persiste a dúvida quanto ao comportamento das respostas, o modelo de quase-verossimilhança também é uma alternativa possível. Esta dissertação apresenta a reanálise de um experimento, apresentado em Arriba (2005), onde algumas respostas são categóricas. Na análise original do experimento, respostas categóricas foram modeladas através de regressão dos mínimos quadrados ordinários, desconsiderando a violação do pressuposto de normalidade das respostas. Na reanálise aqui apresentada, as variáveis são corretamente abordadas usando-se os modelos lineares generalizados. Como o objetivo do trabalho de Arriba (2005) era a otimização de um processo descrito por múltiplas respostas, comparam-se os resultados da otimização mediante as duas estratégias de modelagem das respostas, além de se propor um método alternativo, mais simplificado, de otimização experimental. / This dissertation deals with the optimization of industrial processes using Design of Experiments. In designed experiments, response variables are often considered as normally distributed. However, in some situations, such assumption is violated; for example, when responses express counts, and only non-negative integers numbers may come up as outcomes. In these cases, it is likely that responses follow a Poisson distribution which is then modeled by generalized linear models (GLM), since such distribution is a member of the exponential family. If a question still holds on the responses behavior, their modeling through the quasi-likelihood method is another option that should be considered. This dissertation analyses an experiment performed by Arriba (2005), where some responses are of categorical nature. In the original analysis presented by Arriba (2005), categorical responses were modeled using ordinary least squares regression, violating the normality assumption associated with that method. In the analysis presented here, variables are appropriately modeled using GLM. Since the objective in Arriba (2005) was optimizing a multiresponse process, results from the two optimization processes are compared. In addition, an alternative experimental optimization method, simpler than the one in Arriba (2005), is also presented.
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Use of Machine Learning Algorithms to Propose a New Methodology to Conduct, Critique and Validate Urban Scale Building Energy ModelingJanuary 2017 (has links)
abstract: City administrators and real-estate developers have been setting up rather aggressive energy efficiency targets. This, in turn, has led the building science research groups across the globe to focus on urban scale building performance studies and level of abstraction associated with the simulations of the same. The increasing maturity of the stakeholders towards energy efficiency and creating comfortable working environment has led researchers to develop methodologies and tools for addressing the policy driven interventions whether it’s urban level energy systems, buildings’ operational optimization or retrofit guidelines. Typically, these large-scale simulations are carried out by grouping buildings based on their design similarities i.e. standardization of the buildings. Such an approach does not necessarily lead to potential working inputs which can make decision-making effective. To address this, a novel approach is proposed in the present study.
The principle objective of this study is to propose, to define and evaluate the methodology to utilize machine learning algorithms in defining representative building archetypes for the Stock-level Building Energy Modeling (SBEM) which are based on operational parameter database. The study uses “Phoenix- climate” based CBECS-2012 survey microdata for analysis and validation.
Using the database, parameter correlations are studied to understand the relation between input parameters and the energy performance. Contrary to precedence, the study establishes that the energy performance is better explained by the non-linear models.
The non-linear behavior is explained by advanced learning algorithms. Based on these algorithms, the buildings at study are grouped into meaningful clusters. The cluster “mediod” (statistically the centroid, meaning building that can be represented as the centroid of the cluster) are established statistically to identify the level of abstraction that is acceptable for the whole building energy simulations and post that the retrofit decision-making. Further, the methodology is validated by conducting Monte-Carlo simulations on 13 key input simulation parameters. The sensitivity analysis of these 13 parameters is utilized to identify the optimum retrofits.
From the sample analysis, the envelope parameters are found to be more sensitive towards the EUI of the building and thus retrofit packages should also be directed to maximize the energy usage reduction. / Dissertation/Thesis / Masters Thesis Architecture 2017
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Estudo de modelos ARIMA com variáveis angulares para utilização na perfuração de poços petrolíferos. / Study of ARIMA models with angular variables for use in the drilling of oil wells.SILVA, Areli Mesquita da. 16 July 2018 (has links)
Submitted by Johnny Rodrigues (johnnyrodrigues@ufcg.edu.br) on 2018-07-16T19:54:29Z
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ARELI MESQUITA DA SILVA - DISSERTAÇÃO PPGMAT 2007..pdf: 701919 bytes, checksum: 78ea7b65513f1fe6d83acdb4f3030b43 (MD5)
Previous issue date: 2007-07 / Séries temporais envolvendo dados angulares aparecem nas mais diversas áreas
do conhecimento. Por exemplo, na perfuração de um poço petrolífero direcional, o
deslocamento da broca de perfuração, ao longo da trajetória do poço, pode ser considerado uma realização de uma série temporal de dados angulares. Um dos interesses, neste contexto, consiste em realizar previsões de posicionamentos futuros da broca de perfuração, as quais darão mais apoio ao engenheiro de petróleo na tomada de decisão de quando e como interferir na trajetória de um poço, de modo que este siga o
curso planejado. Neste trabalho, estudamos algumas classes de modelos que podem
ser utilizados para a modelagem desse tipo de série. / Time series involving angular data appear in many diverse areas of scientific
knowledge. For example, in the drilling of a directional oil well, the displacement of
the drill, along the path of the well, can be considered as an angular data time series.
One of the objectives, in this context, consists in carrying out forecasts of the future
positions of the drill, which will give more support to the petroleum engineer in the
decision-making of when and how interfere in the path of a well, so that this follows
the planned course. In this work, we study some classes of models that can be utilized
for the modeling of that kind of series.
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Aplicação de modelos lineares para análise de expressão gênica em experimentos de microarraysHaddad, Samia Ramos [UNESP] 30 January 2007 (has links) (PDF)
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Previous issue date: 2007-01-30Bitstream added on 2014-06-13T19:35:45Z : No. of bitstreams: 1
haddad_sr_me_botfmvz.pdf: 305893 bytes, checksum: 02ff7e2de8b8a9ad8c10e7f22f207754 (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / Universidade Estadual Paulista (UNESP) / O presente trabalho objetivou comparar, utilizando dados de um experimento de Microarray com um delineamento simples, os resultados de diferentes testes estatísticos a fim de verificar suas características na detecção de diferenças no nível de expressão dos genes. Os dados foram provenientes da South Dakota State University-EUA, do Department of Biology and Microbiology, Department of Animal Science, onde toda a parte experimental foi realizada. O material biológico envolveu quatro aves infectadas e quatro não infectadas com o vírus de bronquite infecciosa (IBV). O RNA utilizado foi extraído da camada epitelial da traquéia de animais controle e infectados com o vírus da IBV e, após a transcrição reversa foi marcado com os corantes fluorescentes (Cy3 e Cy5) e hibridizados com o microarray 13k cDNA de aves (FHCRC, Seattle, WA). A análise de dados dos resultados do experimento de microarray englobou dois estágios, sendo o primeiro denominado de Normalização, em que os dados foram pré-processados utilizando o procedimento Loess. A seguir foram realizadas as análises estatísticas propriamente ditas com testes de significância. Utilizou-se um modelo simples de ANOVA e aplicaram-se diferentes metodologias de análise. A análise das imagens revelou que dos 16192 spots em cada slide, apenas 10.926 puderam ser lidos sem defeitos no primeiro slide, 11.633 no segundo slide, 12577 no terceiro e 13.154 no quarto slide. A grande maioria dos spots em branco e controles negativos apresentou defeitos que determinaram sua eliminação. Um total de 13.597 spots foi lido no conjunto dos quatro slides, mas apenas 9.853 spots estavam representados em todos os slides. Concluiu-se que os experimentos de microarray, por tratarem de um conjunto muito grande de observações a serem analisados requerem análises estatísticas específicas. O método de Cui et al. (2005) reduziu... / The aim of this research was to compare, using real data of an experiment of Microarray with a simple design, the results of different statistical tests in order to verify their characteristics in the detection of differences in the level of expression of the genes. The data were coming of South Dakota State University-EUA, of the Department of Biology and Microbiology, Department Animal of Science, where the whole experimental part was accomplished. The biological material involved four infected animals and four no infected with the virus of infectious bronchitis (IBV). Used RNA was extracted of the layer epitelial of the windpipe of animals control and infected with the virus of IBV and, after the reverse transcription it was marked with the fluorescent colors (Cy3 and Cy5) and hybridization with the microarray 13k cDNA of birds (FHCRC, Seattle, WA). The analysis of data of the results of the microarray experiment included two apprenticeships, being the first denominated of Normalization, in that the data were pre-processed using the procedure Loess. To follow the statistical analyses they were accomplished properly said through real data with significant tests. A simple model of ANOVA was used and different analysis methodologies were applied. The analysis of the images revealed that of the 16192 spots in each slide, only 10.926 could be read without defects in the first slide, 11.633 in the second slide, 12577 in the third slide and 13.154 in the fourth slide. The great majority of the spots in white and negative controls presented defects that determined it elimination. A total of 13.597 spots was read in the group of the four slides, but only 9.853 spots were represented in all of the slides. It was ended that the microarray experiments, for they treat of a very big group of observations to be analyzed request specific statistical analyses. The method of Cui et al. (2005) it reduced... (Complete abstract click electronic access below)
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