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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.
321

Produção e avaliação do desempenho de compósitos à base de madeira a partir de insumos alternativos / Production and performance evaluation of wood-based composites from alternative inputs

Amós Magalhães de Souza 11 November 2016 (has links)
A utilização de produtos provenientes de fontes renováveis e livres de substâncias tóxicas é tendência global, prova disso é o constante aumento da demanda por produtos à base de madeira. Segundo o Forest Products Statistics (2015), a produção mundial de painéis de madeira reconstituída, em 2014, foi de 388 milhões de m³, um aumento de 5,5% em comparação com o ano anterior e um aumento de 34% quando comparado com 2010. No entanto, o setor industrial de painéis de madeira há décadas enfrenta um grande desafio com relação às emissões tóxicas vindas dos adesivos convencionais. Diante destes problemas, a proposta do presente trabalho foi testar a viabilidade da produção de painéis aglomerados e painéis OSB, com significativa redução da emissão de formaldeído, a partir de resíduos de madeira de Pinus sp. e Tectona grandis (Teca). Neste sentido, buscou-se contribuir para o aumento do conhecimento científico sobre a utilização do polímero natural polihidroxibutirato (PHB) e do resíduo de tinta à base de resina epóxi como adesivos alternativos. Os painéis foram fabricados variando-se os parâmetros de produção para obtenção de melhores condições de processo, sendo estes: densidade baixa, média e alta; teor de adesivo de 20, 30 e 40%; adição de partículas de Teca nas proporções de 0, 25, 50, 75, 100%. O desempenho físico-mecânico dos painéis foi avaliado com base nas normas ABNT NBR 14810 (2013) e ANSI A208.1 (2009). Realizou-se análise de variância (ANOVA) para testar a influência dos fatores individuais (densidade, percentual de adesivo e fração de Teca), além das interações entre tais fatores nas propriedades físico-mecânicas dos painéis. Os resultados apontaram para excelentes propriedades físicas e mecânicas dos painéis aglomerados de média e alta densidade, tendo resíduo de tinta, principalmente, nas proporções de 30 e 40%. Na maioria dos casos as propriedades de tais painéis foram superiores aos requisitos estipulados pela norma brasileira e pelas internacionais. Assim, ficou confirmada a viabilidade de produção dos aglomerados com pelo menos um dos insumos estudados bem como seu potencial de emprego para as finalidades compatíveis com produtos desta natureza. / The use of products from renewable sources and free of toxic substances is a global trend, the proof is the steady increase in demand for wood-based products. According to the Forest Products Statistics (2015), world production of reconstituted wood panels in 2014 was 388 million cubic meters, an increase of 5.5% compared to the previous year and an increase of 34% compared to 2010. However, the industrial sector of wood panels for decades faces a major challenge with regard to toxic emissions coming from conventional adhesives. Faced with these problems, the purpose of this study was to test the feasibility of production of panels and OSB panels, with significant reduction of formaldehyde emissions from wood waste Pinus sp. and teak (Teak). In this sense, we sought to contribute to the increase of scientific knowledge on the use of natural polymer polyhydroxybutyrate (PHB) and residual ink resin-based epoxy as alternative adhesives. The panels were manufactured by varying the production parameters to obtain the best processing conditions, namely: low density, medium and high; resin content of 20, 30 and 40%; adding particles of Teak in proportions of 0, 25, 50, 75, 100%. The physical-mechanical performance of the panels was evaluated based on the standards NBR 14810 (2013) and ANSI A208.1 (2009). Held analysis of variance (ANOVA) to test the influence of individual factors (density, adhesive percentage and fraction Teak), and the interactions among these factors in the physical-mechanical properties of the panels. The results showed excellent physical and mechanical properties of the panels average clusters and high density, and ink residue, mainly in the proportions of 30 and 40%. In most cases the properties of these boards were superior to the requirements set by the Brazilian and international standards. Thus, it was confirmed production of agglomerates with at least one viability of inputs studied as well as their potential for employment for purposes compatible with products of this nature.
322

Modelagem simultânea de média e dispersão e aplicações na pesquisa agronômica / Joint modeling of mean and dispersion and applications to agricultural research

Afrânio Márcio Corrêa Vieira 10 February 2009 (has links)
Diversos delineamentos experimentais que são aplicados correntemente tomam como base experimentos agronômicos. Esses dados experimentais são, geralmente, analisados usando-se modelos que consideram uma variância residual constante (ou homogênea), como pressuposto inicial. Entretanto, esta pressuposição mostra-se relativamente forte quando se está diante de situações para as quais fatores ambientais ou externos exercem considerável influência nas medidas experimentais. Neste trabalho, são estudados modelos para a média e a variância, simultaneamente, com a variância estruturada de duas formas: (i) por meio de um preditor linear, que permite incorporar variáveis externas e fatores de ruído e (ii) por meio de efeitos aleatórios, que permitem acomodar tanto o efeito longitudinal quanto o efeito de superdispersão, no caso de medidas binárias repetidas no tempo. A classe de modelos lineares generalizados duplos (MLGD) foi aplicada a um estudo observacional que consistiu em medir a mortalidade de frangos de corte no fim da condição de espera pré-abate. Nesse problema, é forte a evidência de que alguns fatores influenciam a variabilidade, e consequentemente, diminuem a precisão das análises inferenciais. Outro problema agronômico relevante, associado à horticultura, são os experimentos de cultura de tecidos vegetais, em que o número de explantes que regeneram são contados. Como esse tipo de experimento apresenta um grande número de parâmetros a serem estimados, comparado ao tamanho da amostra, os modelos existente podem gerar estimativas questionáveis ou até levar a conclusões erroneas, uma vez esse que são baseados em grandes amostras para se fazer inferência estatística. Foi proposto um modelo linear generalizados duplo, para os dados de proporções, de uma perspectiva Bayesiana, visando a análise estatística sob pequenas amostras e a incorporação do conhecimento especialista no processo de estimação dos parâmetros. Um problema clínico, que envolve dados binários medidos repetidamente no tempo é apresentado e são propostos dois modelos que acomodam o efeito da superdispersão e a dependência longitudinal das medidas, utilizandos-se efeitos aleatórios. Foram obtidos resultados satisfatórios nos três problemas estudados. Os MLGD permitiram identificar os fatores associados à mortalidade das aves de corte, o que permitirá minimizar perdas e habilitar os processos de manejo, transporte e abate aos critérios de bem-estar animal e exigências da comunidade européia. O MLGD Bayesiano permitiu identificar o genótipo associado ao efeito de superdispersão, aumentando a precisão da inferência de seleção de variedades. Dois modelos combinados foram propostos logit-normal-Bernoulli-beta e o probit-normal-Bernoulli-beta, que acomodaram satisfatoriamente a superdispersão e a dependência longitudinal das medidas binárias. Esses resultados reforçam a importância de se modelar a média e a variância conjuntamente, o que aumenta a precisão na pesquisa agronômica, tanto em estudos experimentais quanto em estudos observacionais. / Several experimental designs that are currently applied are based on agricultural experiments. These experimental data are, usually, analised with statistical models that assume constant residual variance (or homogeneous), as basic assumption. However, this assumption shows hard to stand for, when environmental or external factors exert strong influence over the measurements. In this work, we study the joint modelling for the mean and the variance, the latter being structured on two ways: (i) through a linear predictor, which allows the incorporation of external variables and/or noise factors and (ii) by the use of random effects, that accommodate jointly the possible overdispersion effect and the dependence of longitudinal data in the case of binary measusurements taken over time. The class of double generalized linear models (DGLM) was applied to an observational study where the poultry mortality was measured in the preslaughter operations. With this situation, it can be observed that there is a strong influence from some environmental factors over the variability observed, and consequently, this reduces the precision of the inferential analysis. Another relevant agricultural problem, related to horticulture, is the tissue culture experiments, where the number of regenerated explants is counted. Usually, this kind of experiment use a large number of parameters to be estimated, when compared with the sample size. The current frequentist models are based on large samples for statistical inference and, under this experimental condition, can generate unreliable estimates or even lead to erroneous conclusions. A double generalized linear model was proposed to analyse proportion data, under the Bayesian perspective, which can be applied to small samples and can incorporate expert knowledge into the parameter estimation process. One clinical research, that measured binary data repeatedly through the time is presented and two models are proposed to fit the overdispersion effect and the dependence of longitudinal measurements, using random effects. It was obtained satisfactory results under these three problems studied. the DGLM allowed to identify factors associated with the poultry mortality, that will allow to minimize loss and improve the process, since the catching until lairage on slaughterhouse, agreeing with animal welfare criteria and the European community rules. The Bayesian DGLM allowed to identify the genotype associated with the overdispersion effect, increasing the precision on the inference about varieties selection. Two combined models were proposed, a logit-normal- Bernoulli-beta and a probit-normal-Bernoulli-beta, which have both addressed the overdispersion effect and the longitudinal dependence of the binary measurements. These results reinforce the importance to modelling mean and dispersion jointly, as a way to increase the precision of agricultural experimentation, be it on experimental studies or observational studies.
323

Análise de observabilidade baseada em variâncias de medidas estimadas = Observability analysis based estimated measures variances / Observability analysis based estimated measures variances

Oliveira, Wilson Aparecido de 21 August 2018 (has links)
Orientador: Madson Cortes de Almeida / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Elétrica e de Computação / Made available in DSpace on 2018-08-21T03:49:32Z (GMT). No. of bitstreams: 1 Oliveira_WilsonAparecidode_M.pdf: 547322 bytes, checksum: ef149ef455996cf448b79577cdb88728 (MD5) Previous issue date: 2012 / Resumo: Este trabalho apresenta uma metodologia completa para analise de observabilidade de sistemas de energia eletrica. A observabilidade da rede e determinada a partir do traco da matriz de covariancia das medidas estimadas, as variancias dos fluxos estimados permitem a identificacao das ilhas observaveis e a restauracao da observabilidade e realizada a partir das variancias das medidas estimadas. As variancias necessarias sao obtidas da matriz de ganho linearizada regularizada. Alem das medidas disponiveis, na formacao da matriz de ganho regularizada admite-se a existencia de pseudomedidas de angulo em todas as barras da rede. O estimador de estado linearizado regularizado e a metodologia de identificacao de ramos observaveis a partir das variancias dos fluxos estimados foram apresentados em [Almeida, Garcia e Asada, 2011]. As novas contribuicoes deste trabalho sao o mecanismo de verificacao da observabilidade, baseado no traco da matriz de covariancia das medidas estimadas, o mecanismo de restauracao da observabilidade, desenvolvido a partir da analise das variancias das medidas, e a inclusao de medicao fasorial sincronizada na formulacao matematica utilizada / Abstract: The purpose of this work is to present a complete methodology for observability analysis of electric power systems. The observability of the network is determined from the trace of the covariance matrix of the measurement estimate, the variance of the estimated power flow allow the identification of observable islands and the restoration of observability is performed from the variance of the measurement estimate. The variances required are obtained from the regularized linearized gain matrix. Besides the measurements available, in the formation of regularized gain matrix allows the existence of voltage angle pseudomeasurements on all buses of the network. The regularized least squares power system state estimation and the methodology of analysis of the variance of the estimated power flow is based in [Almeida, Garcia e Asada, 2011]. The new contributions of this work are the observability checking mechanism, based on the trace of the covariance matrix of the measurement estimate, the mechanism of restoration of observability, developed from the analysis of variance of the measurement and the inclusion of synchronized phasor measurement in the mathematical formulation utilized / Mestrado / Energia Eletrica / Mestre em Engenharia Elétrica
324

Contributions à l'estimation pour petits domaines

Stefan, Marius 26 August 2005 (has links)
Dans la thèse nous nous occupons de l'estimation de la moyenne d'un petit domaine sous un modèle one-fold et utilisant MINQUE pour estimer les composantes de la variance, sous un modèle two-fold avec variances aléatoires, sous des plans noninformatifs et informatifs. / Doctorat en sciences, Orientation statistique / info:eu-repo/semantics/nonPublished
325

Cortisol Awakening Response Is Linked to Disease Course and Progression in Multiple Sclerosis

Kern, Simone, Krause, Ivonne, Horntrich, Antje, Thomas, Katja, Aderhold, Julia, Ziemssen, Tjalf 22 January 2014 (has links)
Objectives: Dysregulation of the hypothalamus-pituitary-adrenal (HPA) axis has frequently been reported in multiple sclerosis (MS). So far, HPA axis function in MS has predominantly been studied under pharmacological stimulation which is associated with a series of methodological caveats. Knowledge of circadian cortisol patterns and cortisol awakening response (CAR) is still limited. Methods: A total of 77 MS patients (55 relapsing-remitting MS (RRMS)/22 secondary-progressive MS (SPMS)) as well as 34 healthy control (HC) subjects were enrolled. Diurnal cortisol release was assessed by repeated salivary cortisol sampling. Neurological disability was rated by the Kurtzke’s Expanded Disability Status Scale (EDSS). Depressive symptoms and perceived stress were assessed by self-report measures. Results: RRMS but not SPMS patients differed in circadian cortisol release from HC subjects. Differences in cortisol release were restricted to CAR. Treated and treatment naïve RRMS patients did not differ in CAR. In a RRMS follow-up cohort (nine months follow-up), RRMS patients with EDSS progression (≥0.5) expressed a significantly greater CAR compared to HC subjects. RRMS patients with a stable EDSS did not differ from HC subjects. Neither depressive symptoms nor perceived stress ratings were associated with CAR in RRMS patients. In a step-wise regression analysis, EDSS at baseline and CAR were predictive of EDSS at follow-up (R2 = 67%) for RRMS patients. Conclusions: Circadian cortisol release, in particular CAR, shows a course specific pattern with most pronounced release in RRMS. There is also some evidence for greater CAR in RRMS patients with EDSS progression. As a consequence, CAR might be of predictive value in terms of neurological disability in RRMS patients. The possible role of neuroendocrine-immune interactions in MS pathogenesis is further discussed.
326

Využití controllingu v podniku / Application of Management Control System in a Company

Zemánek, Zdeněk January 2014 (has links)
The aim of this thesis is to evaluate management control system in a company and pro-pose measures for better use of management control system as a subsystem of manage-ment of the company supporting the achievement of business objectives of the owners in the changing market environment. Thesis consists three main parts. The first theoretical part contains information about management control system. Analysis of the current state of management control system describes state of the management control system in a company and in the last section are suggestions for possible improvements of man-agement control system.
327

Statistické zhodnocení dat / Statistical data evaluation

Fadrný, Tomáš January 2009 (has links)
This diploma thesis evaluates and processes data from final device checks. All the devices are similar types of thermal overcurrent relays by the ABB company. For appropriate statistical data processing, the Minitab 14 statistical software was used and various statistical methods were applied. Results are always listed for each device type and each method used. The diploma thesis is divided into two parts. The first one analyzes the methods used and the second part states the method results. There is also an overall evaluation of the processed data.
328

Multiresolution variance-based image fusion

Ragozzino, Matthew 05 1900 (has links)
Indiana University-Purdue University Indianapolis (IUPUI) / Multiresolution image fusion is an emerging area of research for use in military and commercial applications. While many methods for image fusion have been developed, improvements can still be made. In many cases, image fusion methods are tailored to specific applications and are limited as a result. In order to make improvements to general image fusion, novel methods have been developed based on the wavelet transform and empirical variance. One particular novelty is the use of directional filtering in conjunction with wavelet transforms. Instead of treating the vertical, horizontal, and diagonal sub-bands of a wavelet transform the same, each sub-band is handled independently by applying custom filter windows. Results of the new methods exhibit better performance across a wide range of images highlighting different situations.
329

Statistical Evaluation of Correlated Measurement Data in Longitudinal Setting Based on Bilateral Corneal Cross-Linking

Herber, Robert, Graehlert, Xina, Raiskup, Frederik, Veselá, Martina, Pillunat, Lutz E., Spoerl, Eberhard 13 April 2023 (has links)
Purpose In ophthalmology, data from both eyes of a person are frequently included in the statistical evaluation. This violates the requirement of data independence for classical statistical tests (e.g. t-Test or analysis of variance (ANOVA)) because it is correlated data. Linear mixed models (LMM) were used as a possibility to include the data of both eyes in the statistical evaluation. Methods The LMM is available for a variety of statistical software such as SPSS or R. The application was applied to a retrospective longitudinal analysis of an accelerated corneal cross-linking (ACXL (9*10)) treatment in progressive keratoconus (KC) with a follow-up period of 36 months. Forty eyes of 20 patients were included, whereas sequential bilateral CXL treatment was performed within 12 months. LMM and ANOVA for repeated measurements were used for statistical evaluation of topographical and tomographical data measured by Pentacam (Oculus, Wetzlar, Germany). Results Both eyes were classified into a worse and better eye concerning corneal topography. Visual acuity, keratometric values and minimal corneal thickness were statistically significant between them at baseline (p < 0.05). A significant correlation between worse and better eye was shown (p < 0.05). Therefore, analyzing the data at each follow-up visit using ANOVA partially led to an overestimation of the statistical effect that could be avoided by using LMM. After 36 months, ACXL has significantly improved BCVA and flattened the cornea. Conclusion The evaluation of data of both eyes without considering their correlation using classical statistical tests leads to an overestimation of the statistical effect, which can be avoided by using the LMM.
330

Injector Waveform Monitoring of a Diesel Engine in Real-Time on a Hardware in the Loop Bench

Farooqi, Quazi Mohammed Rushaed 12 1900 (has links)
Indiana University-Purdue University Indianapolis (IUPUI) / This thesis presents the development, experimentation and validation of a reliable and robust system to monitor the injector pulse generated by an Engine Control Module (ECM) and send the corresponding fueling quantity to the real-time computer in a closed loop Hardware In the Loop (HIL) bench. The system can be easily calibrated for different engine platforms as well. The fueling quantity that is being injected by the injectors is a crucial variable to run closed loop HIL simulation to carry out the performance testing of engine, aftertreatment and other components of the vehicle. This research utilized Field Programmable Gate Arrays (FPGA) and Direct Memory Access (DMA) transfer capability offered by National Instruments (NI) Compact Reconfigurable Input-Output (cRIO) to achieve high speed data acquisition and delivery. The research was conducted in three stages. The first stage was to develop the HIL bench for the research. The second stage was to determine the performance of the system with different threshold methods and different sampling speeds necessary to satisfy the required accuracy of the fueling quantity being monitored. The third stage was to study the error and its variability involved in the injected fueling quantity from pulse to pulse, from injector to injector, between real injector stators and cheaper inductor load cells emulating the injectors, over different operating conditions with full factorial design of experimentation and mixed model Analysis Of Variance (ANOVA). Different thresholds were experimented to find out the best thresholds, the Start of Injection (SOI) threshold and the End of Injection (EOI) threshold that captured the injector “ontime” with best reliability and accuracy. Experimentation has been carried out at various data acquisition rates to find out the optimum speed of data sampling rate, trading off the accuracy of fueling quantity. The experimentation found out the expected error with a system with cheaper solution as well, so that, if a test application is not sensitive to error in fueling quantity, a cheaper solution with lower sampling rate and inductors as load cells can be used. The statistical analysis was carried out at highest available sampling rate on both injectors and inductors with the best threshold method found in previous studies. The result clearly shows the factors that affect the error and the variability in the standard deviations in error; it also shows the relation with the fixed and random factors. The real-time application developed for the HIL bench is capable of monitoring the injector waveform, using any fueling ontime table corresponding to the platform being tested, and delivering the fueling quantity in real-time. The test bench made for this research is also capable of studying injectors of different types with the automated test sequence, without occupying the resource of fully capable closed loop test benches for testing the ECM unctionality.

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