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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.
511

Método de formulação de argamassas de revestimento baseado em distribuição granulométrica e comportamento reológico. / Formulation method for rendering mortars based on particle size distribution and rheological behavior.

Cardoso, Fábio Alonso 11 September 2009 (has links)
O desempenho final das argamassas depende das matérias-primas e de suas proporções na formulação, pois estas determinam o comportamento do material na etapa de aplicação e a microestrutura final do material endurecido. Entre as patologias de revestimentos, a falha de aderência é um dos fenômenos mais freqüentes, sendo originada pela incompatibilidade entre o comportamento reológico da argamassa e a energia de lançamento utilizada, resultando em defeitos na interface argamassa substrato. A adequação das características reológicas das argamassas às solicitações envolvidas na aplicação fornece condições de processamento mais favoráveis para a obtenção das máximas propriedades finais do revestimento. Assim, o objetivo do trabalho é desenvolver critérios de formulação, baseados nas características das matérias-primas, nos modelos de empacotamento de partículas e nos comportamentos reológicos, de modo a obter um método de formulação de argamassas. O método de squeeze-flow foi desenvolvido com sucesso para avaliação reológica de argamassas, sendo as principais variáveis experimentais foram estudadas, assim como o efeito do tipo de mistura no comportamento reológico. Procedimento para quantificação da segregação pasta-agregado foi criado, tendo em vista o intenso efeito que este fenômeno exerce sobre o comportamento reológico em squeeze-flow, especialmente em baixas velocidades. Foi ainda comprovado que o squeeze-flow tem boa relação com a percepção do pedreiro, principalmente, nas etapas de lançamento e aperto. Diversas argamassas nacionais e européias foram caracterizadas, resultando em um mapeamento das características de formulação, do comportamento reológico e das propriedades no estado endurecido. Através da aplicação de conceitos de empacotamento e distância de separação de partículas, foi verificado que a otimização do empacotamento de agregados permite um melhor aproveitamento da pasta para promover argamassas com comportamento reológico mais adequado à aplicação ou com menor consumo de finos e água. As correlações estabelecidas entre as características no estado fluido e as propriedades no estado endurecido permitem prever o comportamento das propriedades no estado endurecido com boa confiabilidade. Por fim, são descritas diretrizes sistemáticas para a formulação de argamassas considerando requisitos de desempenho tanto no estado fresco quanto no endurecido. / The in-use performance of rendering mortars depends on the raw materials features and their content in the formulation, since they have major influence on the material behavior during emplacement, as well as, on its final properties. Adherence failure is one of the most frequent problems of this class of building materials, caused by the incompatibility between rheological behavior and the application process, generating mortar/substrate interface flaws. A rheological behavior more suitable to the application demands, provides appropriate conditions to obtain maximum final rendering properties. Therefore, the main goal of this work is to develop mix-design parameters based on raw materials features, particle packing models and rheological behavior, in order to create a mix-design method for mortars. Squeeze-flow technique was successfully adapted for the rheological evaluation of rendering mortars, and the most important experimental parameters were studied. The method is sensitive enough to measure rheological changes as a function of the mixing process applied. Considering that phase segregation plays an important role on the rheological behavior of concentrated suspensions especially at low speeds, a method was developed to measure paste-aggregate segregation. It was also established that the squeeze-flow agrees well with the workers perception during manual emplacement. Several Brazilian and European products were evaluated, and significant differences were determined on the formulation features, rheological behavior and hardened properties. Using models of particle packing and particle distance, it was verified that optimized packing of aggregates enhances rheological behavior and can also allow the reduction of water and fine particles consumption. The experimental relationships established between fresh characteristics, rheological behavior and final properties can be used to predict hardened features and properties with fair confidence. Lastly, mix-design suggestions are made considering both fresh and hardened performance.
512

Is the Family Size of Parents and Children Still Related? Revisiting the Cross-Generational Relationship Over the Last Century

Beaujouan, Eva, Solaz, Anne 04 1900 (has links) (PDF)
In most developed countries, the fertility levels of parents and children are positively correlated. This article analyzes the strength of the intergenerational transmission of family size over the last century, including a focus on this reproduction in large and small families. Using the large-scale French Family Survey (2011), we show a weak but significant correlation of approximately 0.12-0.15, which is comparable with levels in other Western countries. It is stronger for women than men, with a gender convergence across cohorts. A decrease in intergenerational transmission is observed across birth cohorts regardless of whether socioeconomic factors are controlled, supporting the idea that the family of origin has lost implicit and explicit influence on fertility choices. As parents were adopting the two-child family norm, the number of siblings lost its importance for having two children, but it continues to explain lower parity and, above all, three-child families. This suggests that the third child has increasingly become an "extra child" (beyond the norm) favored by people from large families.
513

Estudo morfológico do rim correlacionado com alguns parâmetros da carcaça em bovinos Nelore (Bos indicus) / Morphologic study of kidney correlated with some parameters of the carcass in bovine Nelore

Mesquita, José Ricardo de Carvalho 09 May 2003 (has links)
Foram realizadas mensurações dos rins direito e esquerdo, bem como, de carcaças de bovinos Nelore, inteiros e castrados. As médias gerais dos grupos e os respectivos desvio padrão para as mensurações renais foram: comprimento do rim direito 16,85 &plusmn; 1,10 cm; comprimento do rim esquerdo 16,20 &plusmn; 1,15 cm. As larguras dos rins direito e esquerdo apresentaram médias e desvio padrão iguais a 9,20 &plusmn; 0,80 cm e 9,35 &plusmn; 0,90 cm, respectivamente. Para a variável peso dos rins direito e esquerdo, as médias e desvio padrão foram, respectivamente, de 347,90 Kg &plusmn; 32,55 Kg e 343,25 Kg &plusmn; 32,20 Kg. O número de lobos observados nos rins direito e esquerdo obtiveram médias e desvio padrão de 16,30 &plusmn; 4,50 e 15,90 &plusmn; 3,90, respectivamente. Para as variáveis de carcaça dos grupos envolvidos as médias e respectivos desvios padrão foram: para peso das hemicarcaças direita e esquerda 137,00 &plusmn; 8,00 e 141,10 &plusmn; 8,00 Kg; peso total da carcaça 278,10 &plusmn; 15,90 Kg; rendimento de carcaça 55,80 &plusmn; 1,30%; espessura de gordura 6,30 &plusmn; 2,6 cm; comprimento de carcaça 1,28 &plusmn; 0,03 m. Para comparação das diferentes mensurações, os animais foram divididos em dois grupos (inteiros e castrados). Diferenças significativas (P < 0,01) foram observadas para quase todas as variáveis de carcaça exceto para comprimento da mesma. Para as variáveis de rim, resultados significativos foram observados para largura de rim direito (P < 0,01), peso de rim direito, peso de rim esquerdo e peso total dos rins (P < 0,05). As estimativas de correlações entre todas as características foram de baixa magnitude, indicando ausência de associação entre as diferentes medidas. / Measurement of the right and left kidneys were accomplished, non castrated and castrated carcasses of bovine Nelore. The averages managed of the groups and the respective deviation pattern for the renal measurement were: length of the right kidney 16.85 ± 1.10 cm, respectively; length of the left kidney 16.20 ± 1.15 cm. The widths of the kidneys right and left presented averages and standard deviation to 9.20 ± 0.80 cm and 9.35 ± 0.90 cm, respectively. For the variable weight of the kidneys right and left, the averages and standard deviation were, respectively, of 347.90 Kg ± 32.55 Kg and 343.25 Kg ± 32.20 Kg. The number of lobes observed in the kidneys right and left obtained averages and standard deviation of 16.30 ± 4.50 and 15.90 ± 3.90, respectively. The averages and respective deviation pattern of variables of the involved groups for carcass were: for weight of right and left hemicarcass 137.00 ± 8.00 and 141.10 ± 8.00 Kg total weight of the carcass 278.10 ± 15.90 Kg; carcass exploitation 55.80 ± 1.30%; fat thickness 6.30 ± 2.6 cm, carcass length 1.28 ± 0.03 m. For comparison of the different measurement, the animals were divided in two groups (non castrated and castrated). Significant differences (P <0,01) were observed for almost all the carcass variables except for length. For kidney variables, significant results were observed for width of right kidney (P <0,01), weight of right kidney, weight of left kidney and total weight of kidneys (P <0,05). The estimates of correlations among all the characteristics were of low magnitude, indicating association absence among the different measures.
514

"Os trilhos nas áreas urbanas: conflitos, desafios e oportunidades em dez cidades paulistas" / Railways in urbanized areas: challenging conflicts and opportunities for ten cities in São Paulo state.

Luz, Luciano Ferreira da 24 July 2006 (has links)
O destaque alcançado por um grupo significativo de cidades do interior do estado de São Paulo, que nas últimas décadas só foi mais reforçado pelo dinamismo econômico, evidenciou os aspectos que as projetam como pólos regionais. Nesse grupo de cidades ressalta-se a extrema urbanização, em muitas delas uma avançada conurbação com as vizinhas. Surgem aglomerações, que vão de 500 mil a mais de dois milhões de habitantes, formando uma rede de cidades que lideram o segundo maior mercado consumidor brasileiro. A atividade industrial crescente, a geração de empregos, o conseqüente crescimento demográfico e o espraiamento urbano, deram a essas cidades características de organização espacial muito própria e um sistema viário que não acompanhou esse crescimento, mais expressivo do que os das grandes capitais. Contudo, um elemento está presente em todas essas cidades e constitui um rico patrimônio histórico e, talvez, estratégico em seus futuros: a ferrovia. Nas dez maiores cidades do interior paulista, a presença marcante da velha estação e da linha férrea, que as cruzam e as dividem, são as heranças do processo de desmantelamento e total abandono da função ferroviária de transporte de passageiros de longo percurso. Quase sempre relegadas a funções acessórias no planejamento urbano, a ferrovia também esteve distante, encerrada entre seus muros, mantendo o diálogo com as cidades embaraçado ao longo do tempo. Essa pesquisa se propôs a fazer um levantamento geral desses patrimônios ferroviários, identificar suas interfaces atuais com o meio urbano, os novos agentes envolvidos na sua exploração e, principalmente, a visão e os usos pretendidos pelos municípios para as faixas ferroviárias e suas áreas lindeiras. Buscando amparo nas evoluções históricas, na análise de influências recíprocas e nas relações entre transporte e urbanismo, questiona-se a presença dos trilhos nessas áreas intensamente urbanizadas e são expostas as relações institucionais que devem ser consideradas para planejar e viabilizar o seu aproveitamento, seja pela implantação de novos equipamentos urbanos, pelo uso compartilhado de transportes ou mesmo pela sua erradicação. / A large number of relevant cities in the countryside of São Paulo state has recently faced a remarkable distinction brought by a high economical dinamism in these regional poles during the last decades. These cities already have extreme urbanization rates and they are getting aglomerated, creating new metropolitan areas, with a huge population that is responsible for Brazil´s second largest consuming market. The increasing industrial activity and the offers of new jobs have both stimulated the spreading of its urbanized areas that are not always followed by enough new transportation infra structures. However, one element is very present in any of these cities and it stands for rich historical assets: the old railway. Inside any medium size São Paulo´s city in, the prominent station and the rail tracks still divide the urban center, instersecting its streets and being source of many conflicts and accidents. Nowadays, those abandoned structures are the inheritahe of passenger rail transportation, which was completely dismantled after freight rail transports privatizations. Specially inside the cities, not only the railways were continualy limited to secondary functions in all urban planning process, but the urban transportation was never taken as a priority for rail administration either. This research aimed to build a general view of railway equipments and structures of ten cities, identify possible interfaces with their urban areas, identify the agents envolved in its exploitation and mainly identify what the local expectations to the railways are. The analysis was done based on historical evolution of railways and cities, by the influence of transportation infra structure on territories. Urbanism and public transport organization notions were considered as well, in order to identify the needs and ways on what kind of railway would contribute or would be more profitable in new urban functions.
515

Improved optimality conditions for the Wagner-Whitin algorithm.

January 1988 (has links)
by Ha Yiu Cheung, Albert. / Thesis (M.B.A.)--Chinese University of Hong Kong, 1988. / Bibliography: leaves 90-94.
516

On the single level capacitated lot sizing problem.

January 1998 (has links)
Yip Ka-yun. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1998. / Includes bibliographical references (leaves 107-113). / Abstract also in Chinese. / Chapter Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Overview --- p.1 / Chapter 1.2 --- Our Contributions --- p.2 / Chapter 1.3 --- Organization of the Thesis --- p.4 / Chapter Chapter 2 --- Literature Review --- p.5 / Chapter 2.1 --- Overview --- p.5 / Chapter 2.2 --- Research in Capacitated Lot Sizing Problem without significant setup times --- p.5 / Chapter 2.3 --- Research in Capacitated Lot Sizing Problem with setup time consideration --- p.12 / Chapter 2.4 --- Summary --- p.15 / Chapter Chapter 3 --- Capacitated Lot Sizing Problem with Setup Times --- p.16 / Chapter 3.1 --- Overview --- p.16 / Chapter 3.2 --- Problem Description and Formulation --- p.20 / Chapter 3.2.1 --- Our problem formulation / Chapter 3.2.2 --- Comparison between our problem formulation and traditional problem formulation / Chapter 3.3 --- Description of the Algorithm --- p.26 / Chapter 3.3.1 --- Wagner-Whitin algorithm / Chapter 3.3.2 --- Transportation problem / Chapter 3.3.3 --- Consistence test / Chapter 3.3.4 --- Subgradient optimization / Chapter 3.3.5 --- Computation of lower bound / Chapter 3.4 --- Design of Experiment --- p.43 / Chapter 3.4.1 --- Product demands / Chapter 3.4.2 --- Setup costs / Chapter 3.4.3 --- Setup times / Chapter 3.4.4 --- Capacity costs / Chapter 3.4.5 --- Inventory holding costs / Chapter 3.4.6 --- Quantity of capacity available for production / Chapter 3.4.7 --- Capacity absorption rate / Chapter 3.4.8 --- Generation of larger problems / Chapter 3.4.9 --- Initialization of Lagrangean multipliers / Chapter 3.4.10 --- Close test / Chapter 3.5 --- Open test --- p.58 / Chapter 3.6 --- Managerial Implications --- p.61 / Chapter 3.7 --- Summary --- p.61 / Chapter Chapter 4 --- Capacitated Lot Sizing Problem without Setup Times --- p.63 / Chapter 4.1 --- Overview --- p.63 / Chapter 4.2 --- Problem Description and Formulation --- p.64 / Chapter 4.3 --- Description of the Algorithm --- p.67 / Chapter 4.3.1 --- Decomposition scheme / Chapter 4.3.2 --- Wagner-Whitin algorithm / Chapter 4.3.3 --- Transportation problem / Chapter 4.3.4 --- Subgradient optimization / Chapter 4.3.5 --- Computation of lower bound / Chapter 4.4 --- Design of Experiment --- p.80 / Chapter 4.4.1 --- Product demands / Chapter 4.4.2 --- Setup costs / Chapter 4.4.3 --- Capacity costs / Chapter 4.4.4 --- Inventory holding costs / Chapter 4.4.5 --- Quantity of capacity available for production / Chapter 4.4.6 --- Capacity absorption rate / Chapter 4.4.7 --- Generation of larger problems / Chapter 4.4.8 --- Initialization of Lagrangean multipliers / Chapter 4.4.9 --- Selection of the extent of geometrical reduction and exponential smoothing / Chapter 4.4.10 --- Close test / Chapter 4.5 --- Open test --- p.92 / Chapter 4.6 --- Managerial Implications --- p.95 / Chapter 4.7 --- Comparison with other approaches --- p.96 / Chapter 4.7.1 --- Gilbert and Madan's approach / Chapter 4.7.2 --- Our algorithm for CLS problem with setup time consideration / Chapter 4.8 --- Summary --- p.102 / Chapter Chapter 5 --- Conclusion --- p.104 / Appendix A Vogel's approximation method --- p.106 / Bibliography --- p.107
517

Synthesis Effects on Grain Size and Phase Content in the Anatase-Rutile TiO2 System

Farrell, Kimberly A. 16 August 1999 (has links)
"The phase content and grain size of titanium dioxide often have a strong influence on properties for a variety of applications. In many cases it would be desirable to produce the stable rutile phase with an ultra-fine particle size (<10nm), but most low temperature synthesis methods produce predominantly the metastable anatase phase. The anatase-rutile transformation in TiO2 is known to be affected by dopant type and concentration, as well as the titanium precursor used in solution chemical synthesis. Recently, use of cavitation in the synthesis process has been shown to yield smaller grain size for a variety of oxides. However, the relative importance of these synthesis variables on the grain size and phase content of TiO2 is not well understood. In this study, Taguchi analysis was used to determine the relative effects of dopants (Sn), titanium precursor (butoxide, sulfate, chloride), and cavitation power on grain size and phase content. Precursor residuals were also measured by analytical chemistry. Grain size and phase content results were analyzed statistically to determine whether there is a size dependence of the anatase-rutile transformation. Results show that grain size is strongly dependent on the concentration of chlorine. Absent chlorine, a definite grain size-phase content correlation exists; rutile content increases as grain size decreases. An L-4 orthogonal Taguchi analysis shows chlorine content and tin content as the major influences on the final product. With minimum grain size and maximum rutile content being considered optimal, our best result was 100% rutile and an average grain size of 5nm, which was achieved by acoustic synthesis with 3% tin dopant and low residual chlorine. "
518

Bayesian Inference of a Finite Population under Selection Bias

Xu, Zhiqing 01 May 2014 (has links)
Length-biased sampling method gives the samples from a weighted distribution. With the underlying distribution of the population, one can estimate the attributes of the population by converting the weighted samples. In this thesis, generalized gamma distribution is considered as the underlying distribution of the population and the inference of the weighted distribution is made. Both the models with known and unknown finite population size are considered. In the modes with known finite population size, maximum likelihood estimation and bootstrapping methods are attempted to derive the distributions of the parameters and population mean. For the sake of comparison, both the models with and without the selection bias are built. The computer simulation results show the model with selection bias gives better prediction for the population mean. In the model with unknown finite population size, the distributions of the population size as well as the sample complements are derived. Bayesian analysis is performed using numerical methods. Both the Gibbs sampler and random sampling method are employed to generate the parameters from their joint posterior distribution. The fitness of the size-biased samples are checked by utilizing conditional predictive ordinate.
519

Integrating GIS approaches with geographic profiling as a novel conservation tool

Faulkner, Sally January 2018 (has links)
Geographic profiling (GP) was originally developed to solve the problem of information overload when dealing with cases of serial crime. In criminology, the model uses spatial data relating to the locations of connected crimes to prioritise the search for the criminal's anchor point (usually a home or workplace), and is extremely successful in this field. Previous work has shown how the same approach can be adapted to biological data, but to date the model has assumed a spatially homogenous landscape, and has made no attempt to integrate more complex spatial information (eg, altitude, land use). It is this issue that I address here. In addition, I show for the first time how the model can be applied to conservation data and - taking the model back to its origins in criminology - to wildlife crime. In Chapter 2, I use the Dirichlet Process Mixture (DPM) model of geographic profiling to locate sleep trees for tarsiers in dense jungle in Indonesia, using as input the locations at which calls were recorded, demonstrating how the model can be applied to locating the nests, dens or roosts of other elusive animals and potentially improving estimates of population size, with important implications for management of both species and habitats. In Chapter 3, I show how spatial information in the form of citizen science could be used to improve a study of invasive mink in the Hebrides. In Chapter 4, I turn to the issue of 'commuter crime' in a study of poaching in Savé Valley Conservancy (SVC) in Zimbabwe, in which although poaching occurs inside SVC the majority of poachers live outside, showing how the model can be adjusted to reflect a simple binary classification of the landscape (inside or outside SVC). Finally, in Chapter 5, I combine more complex land use information (estimates of farm density) with the GP model to improve predictions of human-wildlife conflict.
520

General size effect in the Hall-Petch effect and in micromechanical deformation

Li, Yuan January 2017 (has links)
This thesis is a study of the size effect. Improvements on both theoretical work and experimental design are involved in this thesis. The theoretical section focuses on the grain size effect, while the experimental section is related to the micro-foil bending test. Both classic experimental data and theories for the Hall-Petch relationship are reviewed comprehensively. The fitting of the datasets show that the inverse square-root dependence and simple inverse expressions are equally good. The fully Bayesian analysis strongly suggests that the latter is correct. Since the physical mechanism underlying the simple inverse dependence is a general size effect, the precise description of the Hall-Petch effect is that it is a manifestation of the general size effect, instead of having its own special character. Improvements on the classic Stolken and Evans' micro-foil bending experiments are also carried out in this thesis. The smart design of the new equipment eliminates the big risk of error in the classic experiment. By using the new device, precise datasets from the elastic region through the yield point and to high plastic strain area can be obtained. The initial results correspond well with the old published data.

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