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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.
61

Numerical and analytical modeling of sanding onset prediction

Yi, Xianjie 30 September 2004 (has links)
To provide technical support for sand control decision-making, it is necessary to predict the production condition at which sand production occurs. Sanding onset prediction involves simulating the stress state on the surface of an oil/gas producing cavity (e.g. borehole, perforation tunnel) and applying appropriate sand production criterion to predict the fluid pressure or pressure gradient at which sand production occurs. In this work, we present numerical and analytical poroelastoplastic stress models describing stress around producing cavity and verify those models against each other. Using those models, we evaluate the stress state on the cavity surface and derive sanding onset prediction models in terms of fluid pressure or pressure gradient based on the given sand production criterion. We then run field case studies and validate the sanding onset prediction models. Rock strength criterion plays important roles in sanding onset prediction. We investigate how the sanding onset prediction results vary with the selection of one or another rock strength criterion. In this work, we present four commonly used rock strength criteria in sanding onset prediction and wellbore stability studies: Mohr-Coulomb, Hoek-Brown, Drucker-Prager, and Modified Lade criteria. In each of the criterion, there are two or more parameters involved. In the literature, a two-step procedure is applied to determine the parameters in the rock strength criterion. First, the Mohr-Coulomb parameters like cohesion So and internal friction angle ff are regressed from the laboratory test data. Then, the parameters in other criteria are calculated using the regressed Mohr-Coulomb parameters. We propose that the best way to evaluate the parameters in a specific rock strength criterion is to perform direct regression of the laboratory test data using that criterion. Using this methodology, we demonstrate that the effect of various rock strength criteria on sanding onset prediction is less dramatic than using the commonly used method. With this methodology, the uncertainties of the effect of rock strength criterion on sanding onset prediction are also reduced.
62

Feature Selection for Gene Expression Data Based on Hilbert-Schmidt Independence Criterion

Zarkoob, Hadi 21 May 2010 (has links)
DNA microarrays are capable of measuring expression levels of thousands of genes, even the whole genome, in a single experiment. Based on this, they have been widely used to extend the studies of cancerous tissues to a genomic level. One of the main goals in DNA microarray experiments is to identify a set of relevant genes such that the desired outputs of the experiment mostly depend on this set, to the exclusion of the rest of the genes. This is motivated by the fact that the biological process in cell typically involves only a subset of genes, and not the whole genome. The task of selecting a subset of relevant genes is called feature (gene) selection. Herein, we propose a feature selection algorithm for gene expression data. It is based on the Hilbert-Schmidt independence criterion, and partly motivated by Rank-One Downdate (R1D) and the Singular Value Decomposition (SVD). The algorithm is computationally very fast and scalable to large data sets, and can be applied to response variables of arbitrary type (categorical and continuous). Experimental results of the proposed technique are presented on some synthetic and well-known microarray data sets. Later, we discuss the capability of HSIC in providing a general framework which encapsulates many widely used techniques for dimensionality reduction, clustering and metric learning. We will use this framework to explain two metric learning algorithms, namely the Fisher discriminant analysis (FDA) and closed form metric learning (CFML). As a result of this framework, we are able to propose a new metric learning method. The proposed technique uses the concepts from normalized cut spectral clustering and is associated with an underlying convex optimization problem.
63

Design Issues in Nonregular and Follow-Up Split-Plot Designs

Tichon, Jenna Gaylene 10 September 2010 (has links)
In industrial experimentation, time and material costs are often at a premium. In designing an experiment, one needs to balance the desire for sufficient experimental runs to provide adequate data analysis, with the need to conduct a cost-effective experiment. A common compromise is the use of fractional factorial (FF) designs, in which only a fraction of the total possible runs is utilized. After discussing the basic concepts of FF designs, we introduce the fractional factorial split-plot (FFSP) design. Such designs occur frequently, because certain factors are often harder to vary than others, thus imposing randomization restric- tions. This thesis examines two techniques aimed at reducing run size that have not been greatly explored in the FFSP setting — nonregular designs and semifoldover designs. We show that these designs offer competitive alternatives to the more standard regular and full foldover designs and we produce tables of optimal designs in both scenarios.
64

Feed Intake and Feeding Behavior Associations with Performance and Feed Efficiency of Feedlot Cattle Fed a Corn-based Diet

Bailey, Jayton 2011 December 1900 (has links)
The objective of the first study was to determine which combination of bimodal (2-population) distribution models best fit non-feeding interval data to distinguish intervals within (1st population) and between (2nd population) meals in beef cattle fed a corn-based diet. Feeding behavior traits were measured in 119 heifers fed a corn-based diet using a GrowSafe system. Bimodal distribution models were fitted to the log10-transformed interval lengths between bunk visit (BV) events for each animal using Gaussian (G); Weibull (W); Log-Normal; Gamma and Gumbel statistical functions. Criterion (AIC) and likelihood probability estimates. Objectives of the second study were to quantify individual meal criterion and examine the associations between feeding behavior traits, performance, and feed efficiency traits in heifers fed a corn-based diet. Results from study one indicate that the G-W bimodal distribution model is a statistically better fitting and likely a more appropriate model to define meal criterion compared to the standard G-G model used in previous literature. Results from the second study suggest that the meal criterion for heifers fed a corn-based diet is 11.48 min when applying the G-W bimodal model to log-transformed interval lengths between BV events. Moderate phenotypic correlations between feed efficiency (residual feed intake- RFI) and several feeding behavior traits were found. Inclusion of these feeding behavior traits to the base model for RFI accounted for an additional 25% of the variation in DMI not explained by ADG or mid-test BW0.75. Significant (P < 0.05) differences in 11 observed feeding behavior traits between RFI classification groups were also found suggesting that differences in feeding behaviors may contribute to the variation in RFI due to differences in energetic costs related to feeding activities.
65

Design Issues in Nonregular and Follow-Up Split-Plot Designs

Tichon, Jenna Gaylene 10 September 2010 (has links)
In industrial experimentation, time and material costs are often at a premium. In designing an experiment, one needs to balance the desire for sufficient experimental runs to provide adequate data analysis, with the need to conduct a cost-effective experiment. A common compromise is the use of fractional factorial (FF) designs, in which only a fraction of the total possible runs is utilized. After discussing the basic concepts of FF designs, we introduce the fractional factorial split-plot (FFSP) design. Such designs occur frequently, because certain factors are often harder to vary than others, thus imposing randomization restric- tions. This thesis examines two techniques aimed at reducing run size that have not been greatly explored in the FFSP setting — nonregular designs and semifoldover designs. We show that these designs offer competitive alternatives to the more standard regular and full foldover designs and we produce tables of optimal designs in both scenarios.
66

Perspectivismo e relativismo em Nietzsche / Perspectivism and relativism in Nietzsche

Eder Ricardo Corbanezi 06 November 2013 (has links)
Esta dissertação investiga, por meio de uma leitura imanente da filosofia de Nietzsche, a relação problemática entre perspectivismo e relativismo em sua obra. Inscrito na efetividade, concebida como vontades de potência que se exercem de modo perspectivístico e interpretante, o perspectivismo propõe a ideia de que não existem fatos, mas apenas interpretações perspectivísticas. Cumpre então perguntar se tal perspectivismo incorreria num relativismo radical, segundo o qual todas as interpretações seriam equivalentes. Procuraremos mostrar que não é possível responder a esse problema de modo unilateral, com um simples e taxativo sim ou não. Por um lado, o exame de seus escritos indica que Nietzsche não pretenderia assumir a posição de um relativista radical na medida em que hierarquiza as interpretações e reivindica a superioridade de sua própria interpretação de mundo. Mais do que isso, sua filosofia aponta até mesmo para a inviabilização daquele relativismo: ao associar os conceitos de perspectiva e interpretação ao de valor, indica que toda perspectiva e toda interpretação avaliam e hierarquizam, de modo que inexistiriam perspectivas e interpretações que efetivamente considerassem as demais como dotadas de mesmo valor. Por outro lado, se admitida a concepção de uma efetividade perspectivística e interpretativa, então todo e qualquer critério estabelecido para hierarquizar as interpretações teria de ser relativo a uma perspectiva e a uma interpretação determinadas, não consistindo num critério incondicionado e objetivo. Assim, uma vez considerada a relatividade de todo critério, ressurge o problema do relativismo. / This dissertation researches, through an immanent reading of Nietzsches philosophy, the problematic relationship between perspectivism and relativism in his work. Intrinsic in the reality, conceived as wills to power that express themselves in a perspectivist and interpretive way, the perspectivism argues that there are no facts, but only perspectivist interpretations. So it is necessary to ask whether such a perspectivism incur a radical relativism, according to which all interpretations would be equivalent. We shall try to show that it is not possible to answer this problem unilaterally, with a simple yes or no. On the one hand, the examination of his writings indicates that Nietzsche would not intend to take the position of a radical relativist, for he ranks the interpretations and claims the superiority of his own interpretation of the world. More than that, his philosophy would point to the impossibility of that relativism: since Nietzsche associates the concepts of perspective and interpretation with the concept of value, he indicates that every perspective and every interpretation evaluate and rank, so that there would not be perspectives and interpretations that effectively could consider the others as equivalent. On the other hand, if we accept the conception of a perspectivist and interpretive reality, so any criterion fixed in order to rank the interpretations would depend on a certain perspective and interpretation, and thus it would not be an unconditional and objective one. Hence, since we consider that any criterion is relative, the problem concerning relativism resurfaces.
67

Combinação de Características Para Segmentação em Transcrição de Locutores

Neri, Leonardo Valeriano 21 February 2014 (has links)
Submitted by Lucelia Lucena (lucelia.lucena@ufpe.br) on 2015-03-09T19:16:26Z No. of bitstreams: 2 DISSERTAÇÃO Leonardo Valeriano Neri.pdf: 1395784 bytes, checksum: f38db7dc7191951459624c0348b93e63 (MD5) license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) / Made available in DSpace on 2015-03-09T19:16:26Z (GMT). No. of bitstreams: 2 DISSERTAÇÃO Leonardo Valeriano Neri.pdf: 1395784 bytes, checksum: f38db7dc7191951459624c0348b93e63 (MD5) license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Previous issue date: 2014-02-21 / Neste trabalho é apresentada uma abordagem de combinação de características para a etapa de segmentação de locutores em um sistema de transcrição de locutores. Esta abordagem utiliza diferentes características acústicas extraídas da fonte de áudio com o objetivo de combinar as suas capacidades de discriminação para diferentes tipos de sons, aumentando assim, a precisão da segmentação. O Critério de Informação Bayesiana (BIC - Bayesian Information Criterion) é usado como uma medida de distância para verificar a propensão de junção de dois segmentos do áudio. Uma Rede Neural Artificial (RNA) combina as respostas obtidas por cada característica após a aplicação de um algoritmo que detecta se há mudança em um trecho do áudio. Os índices de tempo obtidos são usados como entrada da rede neural que estima o ponto de mudança do locutor no trecho de áudio. Um sistema de transcrição de locutores que inclui a abordagem proposta é desenvolvido para avaliar e comparar os resultados com os do sistema de transcrição que utiliza a abordagem clássica de segmentação de locutores Window-Growing de Chen e Gopalakrishnan, aplicada às diferentes características acústicas adotadas neste trabalho. Nos experimentos com o sistema de transcrição de locutores, uma base artificial contendo amostras com vários locutores é usada. A avaliação dos resultados da etapa de segmentação do sistema mostra um aprimoramento em ambas as taxas de perda de detecção (MDR - Miss Detection Rate) e de falsos alarmes (FAR - False Alarm Rate) se comparadas à abordagem Window-Growing. A avaliação dos resultados na etapa de agrupamento dos locutores mostra uma melhora significativa na pureza dos grupos de locutores formados, calculada como o percentual de amostras de um mesmo locutor no grupo, demostrando que os mesmos são mais homogêneos.
68

Estudo de criterios de resistencia de materiais anisotropicos aplicados a madeira / Study of anisotropic material failure criteria, applied to wood

Nicolas, Elias Antonio 30 June 2006 (has links)
Orientador: Nilson Tadeu Mascia / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Civil, Arquitetura e Urbanismo / Made available in DSpace on 2018-08-07T08:37:01Z (GMT). No. of bitstreams: 1 Nicolas_EliasAntonio_D.pdf: 5212612 bytes, checksum: 6374b5ff3649878b30250be16c1a8e76 (MD5) Previous issue date: 2006 / Resumo: Esta pesquisa refere-se ao estudo de critérios de resistência de materiais anisotrópicos, especialmente o critério tensorial de resistência de TSAI- WU, com aplicações teóricas e experimentais para a madeira. Neste sentido foi realizada uma revisão teórica dos principais temas relacionados à presente pesquisa, como: critérios gerais de resistência, fórmula de hankinson, critério de TSAIWU, modos de ruptura da madeira, fatores que influenciam na resistência da madeira,equipamentos e corpos-de-prova para realização de ensaios uniaxiais e biaxiais, prescrições de cálculo das normas de estruturas de madeira. O objetivo principal deste trabalho foi determinar os parâmetros de resistência do critério tensorial de TSAI-WU, com a finalidade de definir uma superfície de ruptura, para a espécie de madeira estudada, cupiúba (Goupia glabra), e comparar os dados dos ensaios com as estimativas do critério. No estudo experimental foram realizados os seguintes ensaios: tração e compressão, uniaxiais, com ângulos das fibras inclinados em relação ao carregamento (0°, 15°, 30°, 45°, 60°, 75° e 90°); ensaios de cisalhamento paralelo às fibras e ensaios de compressão biaxial. As estimativas do critério de TSAI- WU ficaram próximas das estimativas da fórmula de Hankinson e também dos dados dos ensaios uniaxiais de tração e compressão. Por outro lado, para ensaios biaxiais, o critério de TSAI-WU sofre grande influência do coeficiente de interação.De um modo geral, o critério de TSAI-WU apresenta bons resultados, facilidade de utilização se comparado a outros critérios, devido especialmente a seu caráter tensorial, podendo ser aplicado na avaliação de resistência da madeira e de outros materiais anisotrópicos / Abstract: This research deals with the study of anisotropic material failure criteria, specifically TSAI- WU tensor failure criteria, and theoretical and experimental applications for wood. Thus it was carried out a theoretical revision of the principal themes related to this research: general failure criteria, Hankinson's formula, TSAI-WU tensor criterion, failure modes of wood, factors that affect wood strength, equipaments and specimens for development of uniaxial and biaxial tests and rules of design codes of wood structures. The main objective of this work was to determine the TSAI-WU tensor failure criterion parameters, with the purpose of defining the failure surface, for the wood specie Cupiúba (Goupia Glabra) and of comparing the test results and criterion estimates as well. In the experimental development it was performed the following axial tests: tension and compression, with inclined grain angles in related to the load (0°, 15°, 30°, 45°, 60°, 75° and 90°); shear tests and biaxial compression. The estimates of TSAI-WU criterion were close of Hankinson's formula and the tension and compression tests results too. On the other hand, for biaxial compressive test, TSAI- WU criterion influence ofthe interaction coefficient (F12). In general, TSAI- WU criterion can be applied to evaluate wood strength and other anisotropic materials too, by presenting good results and facility in utilizing especially when comparing to other criteria due to its tensor form / Doutorado / Estruturas / Doutor em Engenharia Civil
69

An Investigation of the Basis of the Strength-Based Criterion-Shift

Olchowski, James E 29 August 2014 (has links)
In recognition memory, participants often fail to change their criterion for making a “studied” response from one trial to the next based on learning strength, even when they are given obvious cues to identify each test item as studied often (“strong”) or studied a single time (“weak”) (e.g., Stretch & Wixted, 1998). In three experiments we tested the hypothesis that participants produce robust item-by-item shifts only when responding did not involve significant response interference (Simon, Acosta, Mewaldt, & Speidel, 1976). In our three experiments, participants studied lists of words studied once (weak) or five times (strong). In Experiment 1, both strong and weak words appeared at test under the questions “Was this studied at all?” or “Was this studied five times?” Participants were randomly assigned to conditions using two keys to respond “yes” or “no”, or using four keys with one set of “yes” and “no” per question. Four-key participants were expected to shift their criteria while 2-key participants could not due to response interference, though results showed that both conditions were capable of criterion-shifting. In Experiment 2 test items appeared on either the left or the right side of the screen; only strong words appeared on the right and only weak words on the left. Participants went through one study-test cycle with four response keys, and one with two. Regardless of the testing conditions, participants did not shift their criteria in the 2-key condition while participants in the 4-key condition did shift their criteria. Finally, Experiment 3 fully crossed 2 or 4 key conditions with blocked or unblocked presentation of test items. Previous experiments have found both number of response keys and blocking of presentations to have an effect on ability to criterion-shift (Hicks & Starns, 2014; Starns & Olchowski, submitted; Verde & Rotello, 2007). Experiment 3 confirmed that number of response keys has a significant effect on criterion-shifting and that it is separate from any effect of blocking. All three experiments suggest that response interference is not the driving force behind criterion-shifting. A new explanation is proposed.
70

A Proposed Method of Student Selection Using a Biographical Inventory as an Adjunctive Predictive Criterion

Orme, Jeffrey Scott 01 May 1980 (has links)
The purpose of this paper was to investigate whether or not the use of a biographical inventory would be a feasible and viable adjunctive means of making more accurate predictions of student success in programs of upper-division and graduate study in speech pathology and audiology. During the past years, biographical inventories have been found to be predictive of creativity, performance as a military officer, performance in varied occupations, and academic performance. It was hypothesized that a biographical inventory could be developed which, when used in conjunction with the existing academic predictors of Grade Point Average and Graduate Records Examination scores, would add to the established selection instruments. As a means of identifying and distinguishing among several levels of competency of students, a student evaluation form was constructed and validated. Items cores from a 257 item biographical inventory were correlated with scores obtained from the student evaluation form and a 52 item biographical inventory for speech pathology and audiology students was developed. Admissions criteria data, student evaluation form scores and biographical inventory scores were placed in two step-wise multiple regression equations and analyzed statistically. Results indicate that biographical factors appear to be of importance to undergraduate success in programs of speech and hearing therapy. Student success in the more rigorous programs of graduate study appears to depend much more on academic ability. Disparate results indicate that the use of a biographical inventory as an adjunctive academic predictor should be approached with caution until further studies can be conducted.

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