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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.
151

Um modelo hierárquico para sistemas de tipos de arquivos implementado como um middleware / A hierarchical model for file type systems implemented as a middleware

Testa, Henrique Gregianin January 2007 (has links)
Com a finalidade de facilitar a manipulação de documentos pelos usuários e aplicações, foram desenvolvidas no decorrer do tempo diversas formas para classificar e organizar esses documentos, incluindo a criação de diferentes mecanismos pertinentes a formatos de arquivos, os chamados sistemas de tipos de arquivos. É possível perceber nesse esforço uma crescente preocupação com a correta identificação dos arquivos e com a obtenção de maiores informações sobre seu conteúdo. Afinal, com esse conhecimento as aplicações e ambientes gráficos dos sistemas operacionais podem adicionar novas funcionalidades na manipulação de documentos e arquivos em geral. Neste trabalho se propõe um novo modelo e arquitetura para sistemas de tipos de arquivos. O modelo se baseia em um grafo de tipos representando relações hierárquicas e um índice de metadados de arquivos, usados em conjunto por funcionalidades que são disponibilizadas através de uma API. A construção do grafo de tipos, que desempenha papel central no modelo proposto, envolveu o estudo dos tipos de arquivos registrados nos principais sistemas operacionais, os tipos definidos pelo IANA (Internet Assigned Numbers Authority) e outros tipos comumente utilizados, com a finalidade de selecionálos e interrelacioná-los em uma hierarquia. A arquitetura proposta para o sistema de tipos é um middleware que oferece os serviços abstraindo operações de baixo nível específicos do sistema operacional. O modelo e arquitetura apresentados neste trabalho beneficia principalmente softwares que trabalham intensamente com arquivos, como IDEs (Integrated Development Environment) e ambientes gráficos. / Several strategies to classify and organize documents by users and applications has being developed in order to facilitate its manipulation, including creation of different mechanisms related to file formats, known as file type systems. It is possible to notice in these works an increasing concern about file identification correctness and obtaining further information regarding its contents as well. This knowledge allow application and graphical environments of operating systems adding new functionalities on manipulation of documents and files. The present work proposes a new model and architecture to file type systems. The model is based on a file type graph representing hierarchical relationships and an index of file metadata. Both are used by functionalities provided through an API. To build the graph of file types, central piece on the proposed model, it was necessary to study file types registered on the most imporant operating systems, types defined by IANA and other types commonly used. The goal is to collect file types and interlink them in a hierarchy. The proposed architecture for the file type system is a middleware which provides services hiding native operating systems low level operations. The model and architecture presented in this work is specially useful to softwares that handle files intensely, like IDEs (Integrated Development Environment) and graphical environments.
152

Um modelo hierárquico para sistemas de tipos de arquivos implementado como um middleware / A hierarchical model for file type systems implemented as a middleware

Testa, Henrique Gregianin January 2007 (has links)
Com a finalidade de facilitar a manipulação de documentos pelos usuários e aplicações, foram desenvolvidas no decorrer do tempo diversas formas para classificar e organizar esses documentos, incluindo a criação de diferentes mecanismos pertinentes a formatos de arquivos, os chamados sistemas de tipos de arquivos. É possível perceber nesse esforço uma crescente preocupação com a correta identificação dos arquivos e com a obtenção de maiores informações sobre seu conteúdo. Afinal, com esse conhecimento as aplicações e ambientes gráficos dos sistemas operacionais podem adicionar novas funcionalidades na manipulação de documentos e arquivos em geral. Neste trabalho se propõe um novo modelo e arquitetura para sistemas de tipos de arquivos. O modelo se baseia em um grafo de tipos representando relações hierárquicas e um índice de metadados de arquivos, usados em conjunto por funcionalidades que são disponibilizadas através de uma API. A construção do grafo de tipos, que desempenha papel central no modelo proposto, envolveu o estudo dos tipos de arquivos registrados nos principais sistemas operacionais, os tipos definidos pelo IANA (Internet Assigned Numbers Authority) e outros tipos comumente utilizados, com a finalidade de selecionálos e interrelacioná-los em uma hierarquia. A arquitetura proposta para o sistema de tipos é um middleware que oferece os serviços abstraindo operações de baixo nível específicos do sistema operacional. O modelo e arquitetura apresentados neste trabalho beneficia principalmente softwares que trabalham intensamente com arquivos, como IDEs (Integrated Development Environment) e ambientes gráficos. / Several strategies to classify and organize documents by users and applications has being developed in order to facilitate its manipulation, including creation of different mechanisms related to file formats, known as file type systems. It is possible to notice in these works an increasing concern about file identification correctness and obtaining further information regarding its contents as well. This knowledge allow application and graphical environments of operating systems adding new functionalities on manipulation of documents and files. The present work proposes a new model and architecture to file type systems. The model is based on a file type graph representing hierarchical relationships and an index of file metadata. Both are used by functionalities provided through an API. To build the graph of file types, central piece on the proposed model, it was necessary to study file types registered on the most imporant operating systems, types defined by IANA and other types commonly used. The goal is to collect file types and interlink them in a hierarchy. The proposed architecture for the file type system is a middleware which provides services hiding native operating systems low level operations. The model and architecture presented in this work is specially useful to softwares that handle files intensely, like IDEs (Integrated Development Environment) and graphical environments.
153

Multilevel multiple imputation: An examination of competing methods

January 2015 (has links)
abstract: Missing data are common in psychology research and can lead to bias and reduced power if not properly handled. Multiple imputation is a state-of-the-art missing data method recommended by methodologists. Multiple imputation methods can generally be divided into two broad categories: joint model (JM) imputation and fully conditional specification (FCS) imputation. JM draws missing values simultaneously for all incomplete variables using a multivariate distribution (e.g., multivariate normal). FCS, on the other hand, imputes variables one at a time, drawing missing values from a series of univariate distributions. In the single-level context, these two approaches have been shown to be equivalent with multivariate normal data. However, less is known about the similarities and differences of these two approaches with multilevel data, and the methodological literature provides no insight into the situations under which the approaches would produce identical results. This document examined five multilevel multiple imputation approaches (three JM methods and two FCS methods) that have been proposed in the literature. An analytic section shows that only two of the methods (one JM method and one FCS method) used imputation models equivalent to a two-level joint population model that contained random intercepts and different associations across levels. The other three methods employed imputation models that differed from the population model primarily in their ability to preserve distinct level-1 and level-2 covariances. I verified the analytic work with computer simulations, and the simulation results also showed that imputation models that failed to preserve level-specific covariances produced biased estimates. The studies also highlighted conditions that exacerbated the amount of bias produced (e.g., bias was greater for conditions with small cluster sizes). The analytic work and simulations lead to a number of practical recommendations for researchers. / Dissertation/Thesis / Doctoral Dissertation Psychology 2015
154

Three Essays on Correlated Binary Outcomes: Detection and Appropriate Models

January 2018 (has links)
abstract: Correlation is common in many types of data, including those collected through longitudinal studies or in a hierarchical structure. In the case of clustering, or repeated measurements, there is inherent correlation between observations within the same group, or between observations obtained on the same subject. Longitudinal studies also introduce association between the covariates and the outcomes across time. When multiple outcomes are of interest, association may exist between the various models. These correlations can lead to issues in model fitting and inference if not properly accounted for. This dissertation presents three papers discussing appropriate methods to properly consider different types of association. The first paper introduces an ANOVA based measure of intraclass correlation for three level hierarchical data with binary outcomes, and corresponding properties. This measure is useful for evaluating when the correlation due to clustering warrants a more complex model. This measure is used to investigate AIDS knowledge in a clustered study conducted in Bangladesh. The second paper develops the Partitioned generalized method of moments (Partitioned GMM) model for longitudinal studies. This model utilizes valid moment conditions to separately estimate the varying effects of each time-dependent covariate on the outcome over time using multiple coefficients. The model is fit to data from the National Longitudinal Study of Adolescent to Adult Health (Add Health) to investigate risk factors of childhood obesity. In the third paper, the Partitioned GMM model is extended to jointly estimate regression models for multiple outcomes of interest. Thus, this approach takes into account both the correlation between the multivariate outcomes, as well as the correlation due to time-dependency in longitudinal studies. The model utilizes an expanded weight matrix and objective function composed of valid moment conditions to simultaneously estimate optimal regression coefficients. This approach is applied to Add Health data to simultaneously study drivers of outcomes including smoking, social alcohol usage, and obesity in children. / Dissertation/Thesis / Doctoral Dissertation Statistics 2018
155

Sistema hierárquico de classificação para mapeamento da cobertura da terra nas escalas regional e urbana

Prado, Fernanda de Almeida [UNESP] 16 February 2009 (has links) (PDF)
Made available in DSpace on 2014-06-11T19:22:25Z (GMT). No. of bitstreams: 0 Previous issue date: 2009-02-16Bitstream added on 2014-06-13T18:49:03Z : No. of bitstreams: 1 prado_fa_me_prud.pdf: 2522184 bytes, checksum: a4acb46054fde8c9233bacf1d5c21128 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Os mapeamentos da cobertura da terra apresentam o relevante papel de permitir avaliar as alterações na paisagem provocadas pela ação antrópica e fornecer importantes informações para o manejo eficiente dos recursos naturais constituindo-se, assim, em ferramentas essenciais para o planejamento regional e urbano. Entretanto, os atuais mapeamentos atendem a propósitos muito específicos e, conseqüentemente, são limitados na sua capacidade de definir a ampla variedade de tipos existentes de cobertura da terra. Nesse contexto, a proposta central desta pesquisa é desenvolver um sistema hierárquico de classificação, amplo e abrangente, partindo de um nível generalizado de definição de classes de cobertura da terra, para mapeamentos em escala regional, e especializando essas classes para ambientes urbanos. Para cada escala de mapeamento é proposta a nomenclatura das classes e os critérios usados para defini-las. Um estudo de caso é desenvolvido para testar o sistema hierárquico em dois níveis de detalhamento distintos, nas escalas regional e urbana, e são utilizadas diferentes abordagens de classificação multiespectral para extrair as informações temáticas de interesse a cada nível de aplicação... / Land cover mappings present the relevant role of allowing to evaluate the changes in the landscape caused by the man's action and to supply important information for the efficient handling of the natural resources. Thus, those are essential tools for the regional and urban planning. However, current mappings are related to very specific purposes and, consequently, they are limited in their capacity to define the wide variety of existent types of land cover. In that context, the main proposal of this research is to develop a wide and including hierarchical classification system, starting from a generalized level of definition of land cover classes for mappings in regional scale and specializing those classes for urban environment. It is proposed the nomenclature of the classes and the criteria used to define them for each scale of mapping. A study case is developed to test the hierarchical system in two detailing levels, in the regional and urban scales, and different approaches of multispectral classification are used to extract the thematic information of interest to each application level... (Complete abstract click electronic access below)
156

Granja Viana: a produção (ideo)lógica do espaço / Granja Viana: (ideo)logical production of space

Ana Cristina Trivelato 27 October 2006 (has links)
O trabalho aqui proposto perseguiu a compreensão e a explicação da constituição da produção espacial num dado fragmento da grande metrópole paulistana, a região da Granja Viana pertencente ao município de Cotia. Os espaços foram sendo privatizados e produzidos de forma hierarquizada e os meios que influenciaram e ainda influenciam na constituição e manutenção de lugares nobres e periféricos dentro de uma mesma região estão estritamente ligados a uma estratégia de (re)produção do capital por meio do mercado imobiliário. A Granja Viana \"vendida\" carrega consigo um ideal de qualidade de vida associado ao requinte e segurança que estabelece uma identidade aos empreendimentos oferecidos. Porém existe algo a mais no espaço e que nem sempre é aparente: trata-se da diversidade e dos conflitos. Nesta região o velho e o novo, assim como a abundância e a raridade se mantêm num permanente fazer e refazer de um espaço que não é homogêneo. / This work attempted to make understandable and to explain how a production of space is established in a small portion of a big city. The object of this study is Granja Viana area located in Cotia city, near São Paulo. This area has been privatized and developed in a hierarchical way, and the means that influenced and still influence the building up and the maintenance of noble places and peripheries in a same region are strictly related to a capital grow strategy thru the real estate market. The \"sold\" Granja Viana carries an ideal of quality life associated to refinement and security, which creates an identity to the offered enterprises. But there is something else in this space, which is not always evident that is diversities and conflicts. Old and new in this region as well as abundance and scarcity, maintain an invariable make and remake of a heterogeneous space.
157

Evaluation of Hierarchical Temporal Memory in algorithmic trading

Åslin, Fredrik January 2010 (has links)
This thesis looks into how one could use Hierarchal Temporal Memory (HTM) networks to generate models that could be used as trading algorithms. The thesis begins with a brief introduction to algorithmic trading and commonly used concepts when developing trading algorithms. The thesis then proceeds to explain what an HTM is and how it works. To explore whether an HTM could be used to generate models that could be used as trading algorithms, the thesis conducts a series of experiments. The goal of the experiments is to iteratively optimize the settings for an HTM and try to generate a model that when used as a trading algorithm would have more profitable trades than losing trades. The setup of the experiments is to train an HTM to predict if it is a good time to buy some shares in a security and hold them for a fixed time before selling them again. A fair amount of the models generated during the experiments was profitable on data the model have never seen before, therefore the author concludes that it is possible to train an HTM so it can be used as a profitable trading algorithm.
158

Adapting Mode-Switches into the hierarchical scheduling

VILLALBA, DANIEL SANCHEZ January 2013 (has links)
Mode switches are used to partition the system’s behavior into different modes to reduce the complexity of large embedded systems. Such systems is said to operate in multiple modes where each mode corresponds to a specific application scenario, are called Multi-Mode Systems (MMS). Normally, a different piece of software is executed for each mode. At a specific time, the system can be in one of the predefined modes and is switched from one mode to another upon some condition. A mode switch mechanism (or mode change protocol) is used to transform the system from one mode to another at run-time.In this thesis we have used a hierarchical scheduling framework to implement a multi-mode system, called Multi-Mode Hierarchical Scheduling Framework (MMHSF). A two-level Hierarchical Scheduling Framework (HSF) has already been implemented in an open source real-time operating system, FreeRTOS, to support temporal isolation among real-time components. The main contribution in this thesis is the extension of the HSF with the multi-mode feature with the emphasis of doing minimal changes in the underlying operating system FreeRTOS and its HSF implementation. Our implementation uses fixed-priority preemptive scheduling at both local and global scheduling levels and idling periodic servers. The implementation now supports different modes of the system which can be switched at run-time Each subsystem and task exhibit different timing attributes for different modes, and upon a Mode Change Request (MCR) the task-set and timing interfaces of the whole system (including subsystems and tasks) are changed. A Mode Change Protocol specifies the way to change the system-mode. An application may not only need to change a mode but also a different mode change protocol semantic. For example, the mode change from normal to shutdown can allow all the tasks to be completed before the mode is changed. While changing a mode from normal to emergency may require aborting all the tasks instantly. In our work, both the system mode and the mode change protocol can be changed at run-time. We have implemented three different mode change protocols to switch from one mode to another: the Suspend/resume protocol, Abort protocol and Complete protocol. These protocols increase the flexibility of the system, letting the users to select the way they want to switch to the new mode.The implementation of MMHSF is tested and evaluated on an AVR-based 32 bit board EVK1100 with an AVR32UC3A0512 micro-controller. We have tested the behavior of each mode of the system and for each mode change protocol. We also provide the results for the performance measures of all mode change protocols in the thesis.
159

The performance of Multilevel Structural Equation Modeling (MSEM) in comparison to Multilevel Modeling (MLM) in multilevel mediation analysis with non-normal data

Pham, Thanh Vinh 17 November 2017 (has links)
The mediation analysis has been used to test if the effect of one variable on another variable is mediated by the third variable. The mediation analysis answers a question of how a predictor influences an outcome variable. Such information helps to gain understanding of mechanism underlying the variation of the outcome. When the mediation analysis is conducted on hierarchical data, the structure of data needs to be taken into account. Krull and MacKinnon (1999) recommended using Multilevel Modeling (MLM) with nested data and showed that the MLM approach has more power and flexibility over the standard Ordinary Least Squares (OLS) approach in multilevel data. However the MLM mediation model still has some limitations such as incapability of analyzing outcome variables measured at the upper level. Preacher, Zyphur, and Zhang (2010) proposed that the Multilevel Structural Equation Modeling (MSEM) will overcome the limitation of MLM approach in multilevel mediation analysis. The purpose of this study was to examine the performance of the MSEM approach on non-normal hierarchical data. This study also aimed to compare the MSEM method with the MLM method proposed by MacKinnon (2008) and Zhang, Zyphur, and Preacher (2009). The study focused on the null hypothesis testing which were presented by Type I error, statistical power, and convergence rate. Using Monte Carlo method, this study systematically investigates the effect of several factors on the performance of the MSEM and MLM methods. Designed factors considered were: the magnitude of the population indirect effect, the population distribution shape, sample size at level 1 and level 2, and the intra-class correlation (ICC) level. The results of this study showed no significant effect of the degree of non-normality on any performance criteria of either MSEM or MLM models. While the Type I error rates of the MLM model reached the expected alpha level as the group number was 300 or higher, the MSEM model showed very conservative performance in term of controlling for the Type I error with the rejection rates of null conditions were zero or closed to zero across all conditions. It was evident that the MLM model outperformed the MSEM model in term of power for most simulated conditions. Among the simulation factors examined in this dissertation, the mediation effect size emerged as the most important one since it is highly associated with each of the considered performance criteria. This study also supported the finding of previous studies (Preacher, Zhang, & Zyphur, 2011; Zhang, 2005) about the relationship between sample size, especially the number of group, and the performance of either the MLM or MSEM models. The accuracy and precision of the MLM and MSEM methods were also investigated partially in this study in term of relative bias and confidence interval (CI) width. The MSEM model outperformed the MLM model in term of relative bias while the MLM model had better CI width than the MSEM model. Sample size, effect size, and ICC value were the factors that significantly associate with the performance of these methods in term of relative bias and CI width.
160

Attentional Window and Global/Local Processing

Schultz, Steven Peter 16 June 2016 (has links)
How does the focus of attention influence the encoding of information? Research has shown that size and allocation of the attentional window has an influence on what information is attended to or missed. The size-scale of features also effects processing of visual information. Previous research involving hierarchical stimuli suggests precedence for global features. In the present experiment, I investigated the influence of attentional window size on accuracy of encoding hierarchical stimuli at the global and local level. Here I introduce a new method for manipulating the size of the attentional window and for collecting unconstrained responses. At the start of each trial, observers tracked a dashed-line rectangular box, which either broadened or narrowed in size after onset. This sequence was immediately followed by a brief presentation of two hierarchical letters presented simultaneously on the left and right sides of the screen. The box preceding the hierarchical letters either broadened to a size large enough to include both letters at the global level, or narrowed to a size small enough to include a maximum of two letters at the local level at either side of the screen. Observers reported all letters they were able to identify. Results from two experiments indicate an overall precedence of global letters. However, a narrow attentional window reduced global precedence, as would be expected with more focused attention. The narrow windows also produced more same-side identifications of both global and local letters. The second experiment also showed that reducing the processing time decreased the global advantage.

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