• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 314
  • 157
  • 141
  • 68
  • 54
  • 29
  • 19
  • 10
  • 9
  • 8
  • 7
  • 6
  • 6
  • 6
  • 5
  • Tagged with
  • 925
  • 121
  • 75
  • 65
  • 64
  • 57
  • 55
  • 50
  • 50
  • 49
  • 48
  • 46
  • 44
  • 42
  • 42
  • 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.
471

Seed Coat Color in Flax (Linum usitatissimum L.) Conditioned by the b1 Locus, its Linkage with Simple Sequence Repeat Markers (SSRs) and its Association with Flower Shape, Flower Color, Fatty Acid Profile and Grain Yield

2015 January 1900 (has links)
Previously seed coat color in flax has been used as a phenotypic marker for specialty quality traits and currently there is an increasing demand to use seed coat color in flax to market flax for human and animal nutrition uses. Seed coat color was studied to 1) understand the inheritance of seed coat color conditioned by the b1 locus, to 2) understand the relationship of other important flax traits with seed coat color as well as to 3) identify markers that are linked to seed coat color for future marker assisted selection of seed coat color. Spearman’s rank correlation and an allelism test was used to show the inheritance of the alleles at the b1 locus. Bulked segregant analysis (BSA) was used to identify putatively linked markers with the b1 locus, these were then screened on the CDC Bethune x M96006 recombinant inbred line population. Furthermore, the CDC Bethune x M96006 and CDC Bethune x USDA-ARS Crystal recombinant inbred line populations were used to identify any important flax traits that had a significant relationship with seed coat color. It was shown that seed coat color conditioned by the b1 locus was stably inherited and that b1vg and b1 are allelic to one another. The results of the BSA showed that there were 17 candidates for linkage but when these markers were screened on the population only the Lu456 from linkage group (LG) six was identified to have linkage (χ²=3.90; P<0.05) with the b1 locus. Additionally, it was shown that the b1 seed coat color allele of the b1 locus had a pleiotropic effect on flower color and flower shape and that seed coat color was associated with linolenic fatty acid content. None of the traits examined were found to be associated with the b1vg allele of this locus. These results show that the b1 locus is likely present on linkage group six, more marker coverage on linkage group six of markers that are polymorphic between the two seed coat color parents would increase the accuracy of detection. Lastly, this study showed that plant breeders should consider using the b1vg allele that conditions the variegated seed coat color to mark unique lines with important combinations of traits because it sorted independently for seed quality traits. Whereas, the yellow seed coat color conditioned by the b1 allele was found to be associated with higher linolenic fatty acid content and the semi-lethality of this allele would make it not suitable for use in parental lines.
472

Compactification d'espaces homogènes sphériques sur un corps quelconque

Huruguen, Mathieu 29 November 2011 (has links) (PDF)
Cette thèse porte sur les plongements d'espaces homogènes sphériques sur un corps quelconque. Dans une première partie, on aborde la classification de ces plongements, dans la lignée des travaux de Demazure et bien d'autres sur les variétés toriques, et de Luna, Vust et Knop sur les variétés sphériques. Dans une seconde partie, on généralise en caractéristique positive certains résultats obtenus par Bien et Brion portant sur les plongements complets et lisses qui sont log homogènes, c'est-à-dire dont le bord est un diviseur à croisements normaux et le fibré tangent logarithmique associé est engendré par ses sections globales. Dans une dernière partie, on construit par éclatements successifs une compactification lisse et log homogène explicite du groupe linéaire (différente de celle obtenue par Kausz). En prenant dans cette compactification les points fixes de certains automorphismes, on en déduit alors la construction de compactifications lisses et log homogènes de certains groupes semi-simples classiques.
473

Texture et comportement des matériaux granulaires à grande polydispersité

Voivret, Charles 25 November 2008 (has links) (PDF)
Ce travail de thèse est consacré à la modélisation et à l'étude numérique de la texture et du comportement mécanique des matériaux granulaires à grande polydispersité. La polydispersité est considérée en termes d'étalement et de courbure de la distribution de tailles. Afin d'aboutir à des distributions de tailles représentatives, une méthode de génération ainsi qu'un modèle de courbe granulométrique sont présentés. La mise en place de grands échantillons denses par une méthode géométrique a permis de réaliser une étude systématique de l'influence de la polydispersité sur la texture. Le comportement mécanique est étudié par simulations numériques discrètes sur la base de la méthode de Dynamique des Contacts. Les échantillons sont successivement soumis à une relaxation uniaxiale et à un cisaillement simple avec des conditions aux limites périodiques afin d'atteindre respectivement l'état d'équilibre statique et l'état stationnaire après un cisaillement long. Nos résultats montrent que la distribution uniforme par fraction volumique conduit à la compacité la plus élevée. Dans l'état stationnaire, la résistance au cisaillement est indépendante de la polydispersité. Une analyse systématique de la texture permet de montrer que cette propriété résulte, d'une part, de la compensation mutuelle entre les anisotropies des directions de contact et des longueurs des vecteurs branches et, d'autre part, du fait que les forces fortes sont essentiellement transmise à travers les plus grosses particules. Enfin, en présence de forces d'adhésion, la cohésion de Coulomb augmente avec l'étalement granulométrique.
474

Voltage Dependent Ion Transport by Bolaamphilphilic Oligoester Ion Channels

Zong, Ye 17 April 2014 (has links)
Based on preliminary reports, an extended series of bolamphiphilic oligoester compounds with structural symmetry were synthesized and then tested using a planar bilayer experiment with the voltage-clamp technique. The main structures of these compounds are identical, consisting of a mono or tri-aromatic core, two octamethylene chains and two benzoyl headgroups which are all connected through ester linkages. The structural variance was provided by the four differently functionalized benzoyl headgroups. The synthetic methods of three to five steps were mainly adapted from the previously reported method.1 The methods successfully produced eight compounds with overall yields of 20 to 30%. The voltage-clamp data suggested voltage-dependent behaviors occur at low concentrations while Ohmic behaviors require at high concentrations. The activity at low potentials showed relatively erratic behavior but the channels frequently switched between opening and closing states. The activity at high potential lasted longer as the channel maintained a longer state of opening. The exponential voltage-dependent behaviors were observed at higher potential while the voltage-independent Ohmic behaviors occur at low potential. These channel behaviors are highly time-dependent as there is no control over the stability and the aggregation level for the compounds forming active channels in the membrane. In some cases the current-voltage responses appear to be asymmetrical between the positive and the negative potentials. Mechanisms consistent with the observations are proposed. / Graduate / 0485 / 0490 / yzong@uvic.ca
475

Voltage Dependent Ion Transport by Bolaamphilphilic Oligoester Ion Channels

Zong, Ye 17 April 2014 (has links)
Based on preliminary reports, an extended series of bolamphiphilic oligoester compounds with structural symmetry were synthesized and then tested using a planar bilayer experiment with the voltage-clamp technique. The main structures of these compounds are identical, consisting of a mono or tri-aromatic core, two octamethylene chains and two benzoyl headgroups which are all connected through ester linkages. The structural variance was provided by the four differently functionalized benzoyl headgroups. The synthetic methods of three to five steps were mainly adapted from the previously reported method.1 The methods successfully produced eight compounds with overall yields of 20 to 30%. The voltage-clamp data suggested voltage-dependent behaviors occur at low concentrations while Ohmic behaviors require at high concentrations. The activity at low potentials showed relatively erratic behavior but the channels frequently switched between opening and closing states. The activity at high potential lasted longer as the channel maintained a longer state of opening. The exponential voltage-dependent behaviors were observed at higher potential while the voltage-independent Ohmic behaviors occur at low potential. These channel behaviors are highly time-dependent as there is no control over the stability and the aggregation level for the compounds forming active channels in the membrane. In some cases the current-voltage responses appear to be asymmetrical between the positive and the negative potentials. Mechanisms consistent with the observations are proposed. / Graduate / 0485 / 0490 / yzong@uvic.ca
476

Heuristic methods for solving two discrete optimization problems

Cabezas García, José Xavier January 2018 (has links)
In this thesis we study two discrete optimization problems: Traffic Light Synchronization and Location with Customers Orderings. A widely used approach to solve the synchronization of traffic lights on transport networks is the maximization of the time during which cars start at one end of a street and can go to the other without stopping for a red light (bandwidth maximization). The mixed integer linear model found in the literature, named MAXBAND, can be solved by optimization solvers only for small instances. In this manuscript we review in detail all the constraints of the original linear model, including those that describe all the cyclic routes in the graph, and we generalize some bounds for integer variables which so far had been presented only for problems that do not consider cycles. Furthermore, we summarized the first systematic algorithm to solve a simpler version of the problem on a single street. We also propose a solution algorithm that uses Tabu Search and Variable Neighbourhood Search and we carry out a computational study. In addition we propose a linear formulation for the shortest path problem with traffic lights constraints (SPTL). On the other hand, the simple plant location problem with order (SPLPO) is a variant of the simple plant location problem (SPLP) where the customers have preferences on the facilities which will serve them. In particular, customers define their preferences by ranking each of the potential facilities. Even though the SPLP has been widely studied in the literature, the SPLPO has been studied much less and the size of the instances that can be solved is very limited. In this manuscript, we propose a heuristic that uses a Lagrangean relaxation output as a starting point of a semi-Lagrangean relaxation algorithm to find good feasible solutions (often the optimal solution). We also carry out a computational study to illustrate the good performance of our method. Last, we introduce the partial and stochastic versions of SPLPO and apply the Lagrangean algorithm proposed for the deterministic case to then show examples and results.
477

A framework to manage uncertainties in cloud manufacturing environment

Yadekar, Yaser January 2016 (has links)
This research project aims to develop a framework to manage uncertainty in cloud manufacturing for small and medium enterprises (SMEs). The framework includes a cloud manufacturing taxonomy; guidance to deal with uncertainty in cloud manufacturing, by providing a process to identify uncertainties; a detailed step-by-step approach to managing the uncertainties; a list of uncertainties; and response strategies to security and privacy uncertainties in cloud manufacturing. Additionally, an online assessment tool has been developed to implement the uncertainty management framework into a real life context. To fulfil the aim and objectives of the research, a comprehensive literature review was performed in order to understand the research aspects. Next, an uncertainty management technique was applied to identify, assess, and control uncertainties in cloud manufacturing. Two well-known approaches were used in the evaluation of the uncertainties in this research: Simple Multi-Attribute Rating Technique (SMART) to prioritise uncertainties; and a fuzzy rule-based system to quantify security and privacy uncertainties. Finally, the framework was embedded into an online assessment tool and validated through expert opinion and case studies. Results from this research are useful for both academia and industry in understanding aspects of cloud manufacturing. The main contribution is a framework that offers new insights for decisions makers on how to deal with uncertainty at adoption and implementation stages of cloud manufacturing. The research also introduced a novel cloud manufacturing taxonomy, a list of uncertainty factors, an assessment process to prioritise uncertainties and quantify security and privacy related uncertainties, and a knowledge base for providing recommendations and solutions.
478

Uma solução baseada em SNMP para gerenciamento de dispositivos de rede com suporte à virtualização

Daitx, Fábio Fabian January 2011 (has links)
A virtualização de rede surgiu como uma alternativa para contornar as limitações no uso compartilhado da infraestrutura atual da Internet. Com a virtualização, sob uma mesma estrutura física, ou substrato, é possível a construção de múltiplas redes virtuais, cada uma das quais empregando seus próprios protocolos, mecanismos de endereçamento e políticas de forma independente e isolada. Essas redes são formadas por roteadores, interfaces e enlaces virtuais mapeados sobre componentes reais. Por serem desacopláveis, os elementos virtuais trazem uma grande flexibilidade, sendo possível a construção de múltiplas redes sobrepostas para usuários com demandas distintas, por exemplo. Roteadores virtuais podem migrar de um roteador físico para outro, conforme necessidades de manutenção ou balanceamento de carga. Além disso, a possibilidade de se conduzir experimentos de rede em uma estrutura real, sujeita as condições de utilização e de tráfego que normalmente serão encontradas na prática, sem que se precise interromper a operação da rede, traz a possibilidade de se instalar poderosos e sofisticados ambientes de teste (testbeds ). Nesse ambiente, contudo, existem desafios de pesquisa a serem tratados e questões em aberto, em especial com relação ao gerenciamento de dispositivos. Em uma rede com suporte a virtualização, os roteadores físicos precisam ser gerenciados para que roteadores virtuais possam ser criados, modificados, duplicados, destruídos e movimentados. As interfaces de gerenciamento atuais, porém, não suportam tais ações de forma efetiva, obrigando o administrador dos dispositivos a realizar intervenções manuais através de interfaces de linha de comandos (CLIs) não padronizadas. Existe, assim, a necessidade de se definir uma interface de gerenciamento adequada para roteadores físicos que abrigam roteadores virtuais. Tendo como objetivo abordar estas questões, este trabalho consiste na investigação de uma solução para gerenciar roteadores virtuais. Para isto foram levantadas e definidas as principais ações de gerenciamento necessárias aos dispositivos, de forma integrada, visando a definição de uma interface padronizada de gerencia- mento para cenários heterogêneos de utilização. / Network virtualization emerged as an alternative to overcome limitations on use of the shared infrastructure of current Internet. With virtualization, over the same physical structure, or substrate, it is possible to build multiple virtual networks, each of them employing its own protocols, addressing mechanisms and policies, on an isolated and independent way. These networks are formed by virtual routers, interfaces and links mapped to real components. Because they are detachable, the virtual elements bring a great flexibility, being possible constructing many overlaid networks for users with different demands, for example. Virtual routers can migrate from one physical router to another as needed form maintenance or load balancing. Besides, the possibily of running network experiments in a real structure, subject to the conditions of use and traffic that will normally be encountered in practice, without interrupting network operation, make it possible to install powerfull and sofisticated testbeds. In such environment, however, there are research challenges to be managed and open questions, specially related to devices management. In a network with virtu- alization support, physicall routers must be managed so that virtual routers can be created, modified, copied, removed and moved. Nevertheless, current management interfaces do not support such action in an effictive way, compelling the devices manager to make manual interventions through non standardized command line interfaces (CLIs). So, there exist the need to define an adequate management interface for physicall routers that host virtual routers. Having as an objective to address these questions, this work consist in investi- gating a solution to manage virtual routers. For this, were raised and defined the main management actions required for devices, through an integrated way, aiming to define a standardized management interface for heterogeneous use scenarios.
479

Comportamento de hidratação e resposta cisalhante cíclica de resíduo de mineração cimentado reforçado com fibras

Festugato, Lucas January 2011 (has links)
As propriedades do solo cotidianamente podem não ser adequadas às características e às necessidades de projeto. É apresentada, como alternativa, a técnica de reforço com inclusão de elementos fibrosos à matriz de solo cimentado e não cimentado. Ainda, embora comuns, o comportamento do solo frente a solicitações cíclicas não é completamente conhecido. Nesse sentido, o estudo do comportamento de hidratação e da resposta cisalhante cíclica de um resíduo de mineração cimentado reforçado com fibras é objetivado. Para tanto, medidas de retração química, medidas de rigidez ao longo da hidratação e ensaios simple shear monotônicos e cíclicos foram realizados com resíduo de mineração cimentado e não cimentado, reforçado com fibras e não reforçado. O resíduo, oriundo da mineração de ouro, um silte arenoso com traços de argila, foi cimentado com diferentes teores de cimento Portland, entre 0% e 10% em relação à massa de solo seco, e reforçado com 0% e 0,5%, em relação à massa de sólidos secos, de fibras de polipropileno de 50mm de comprimento e 0,1mm de espessura, equivalentes a um índice aspecto de 500. Os resultados demonstraram que as fibras não afetaram o processo de hidratação das misturas de resíduo de mineração cimentadas, que apresentam tendência de atenuação logarítmica da retração química com o tempo. Quanto maiores as relações água/cimento, maior o nível de retração química. A inclusão de fibras a misturas de resíduo de mineração cimentadas, da mesma forma, não afetou a evolução dos valores de rigidez inicial, que crescem com tendência logarítmica em função do tempo e aumentam com o acréscimo do nível de cimentação. Sob condições monotônicas de cisalhamento, a adição de fibras conferiu ao material cimentado e não cimentado comportamento de endurecimento. Sob condições cíclicas de deformação cisalhante controlada, as fibras não afetaram a resposta cisalhante das amostras não cimentadas e provocaram aumento dos valores da tensão cisalhante das amostras cimentadas após sucessivos ciclos de esforços. Sob condições cíclicas de tensão cisalhante controlada, a adição de fibras às misturas não cimentadas proporcionou o aumento da resistência aos ciclos de esforços e às misturas cimentadas provocou aumento dos níveis de deformação cisalhante. A concordância das mesmas envoltórias de resistência tanto às trajetórias de tensões dos ensaios monotonônicos quanto às trajetórias dos ensaios cíclicos sob diferentes condições de carregamento possibilitou a obtenção dos mesmos parâmetros de resistência das misturas analisadas sob diferentes condições de carregamento. / The soil properties commonly may not suit the project characteristics and requirements. It is presented, as alternative, the improvement technique of fibrous elements inclusion to the cemented and uncemented soil matrix. Moreover, although common, the behaviour of soil under cyclic loads is not completely known. In this sense, the study of the hydration behaviour and the cyclic shear response of fibre reinforced cemented mine tailings is the main objective of this research. Therefore, chemical shrinkage measurements, stiffness measurements during hydration and monotonic and cyclic simple shear tests were conducted on fibre reinforced and unreinforced cemented and uncemented mine tailings. The tailings, produced from gold mining, are classified as a sandy silt with traces of clay and were cemented with different amounts of Portland cement, ranging from 0% to 10% by dry weigh of soil, and reinforced with 0% and 0.5% by dry weigh of solids of polypropylene fibers 50mm long and 0.1mm thick, equivalent to an aspect ratio of 500. The results showed fibres did not affect the hydration process of cemented mine tailings mixtures, which presents logarithmic attenuation of chemical shrinkage over time. The greater the water / cement ratio, the higher the level of chemical shrinkage. The inclusion of fibers to cemented mine tailings, likewise, did not affect the evolution of initial stiffness values, that raise logarithmic over time and increase with the increase of the cementation level. Under monotonic shear conditions, the addition of fibers confers hardening behaviour to the uncemented and cemented materials. Under shear strain controlled cyclic conditions, fibres did not affect the shear response of uncemented samples and increased shear stress values of cemented samples after successive load cycles. Under shear stress controlled cyclic conditions, the fibres addition to the uncemented mixtures increased the resistance to load cycles and to the cemented mixtures increased levels of shearing strain. The agreement of the same strength envelopes to both monotonic and cyclic stress paths, under different cyclic loading conditions, allows the use of the same strength parameters of mixtures analyzed under different loading conditions.
480

A influência da retomada e da distância sintática no processamento de pronomes plenos e nulos em português brasileiro / The influence of the resumption and syntactic distance in processing of overt and null pronouns in brazilian portuguese

Lima, Alisson Hudson Veras January 2015 (has links)
LIMA, Alisson Hudson Veras. A influência da retomada e da distância sintática no processamento de pronomes plenos e nulos em português brasileiro. 2015. 125f. – Dissertação (Mestrado) – Universidade Federal do Ceará, Departamento de Letras Vernáculas, Programa de Pós-graduação em Linguística, Fortaleza (CE), 2015. / Submitted by Márcia Araújo (marcia_m_bezerra@yahoo.com.br) on 2015-12-16T11:00:52Z No. of bitstreams: 1 2015_dis_ahvlima.pdf: 1504481 bytes, checksum: 7b0ae6c958059522afa390017a5f66a0 (MD5) / Approved for entry into archive by Márcia Araújo(marcia_m_bezerra@yahoo.com.br) on 2015-12-16T11:02:39Z (GMT) No. of bitstreams: 1 2015_dis_ahvlima.pdf: 1504481 bytes, checksum: 7b0ae6c958059522afa390017a5f66a0 (MD5) / Made available in DSpace on 2015-12-16T11:02:39Z (GMT). No. of bitstreams: 1 2015_dis_ahvlima.pdf: 1504481 bytes, checksum: 7b0ae6c958059522afa390017a5f66a0 (MD5) Previous issue date: 2015 / In this dissertation we investigated how repeated names, overt pronouns and null pronouns are corefentially processed in Brazilian Portuguese (PB). Gordon, Grosz & Gilliom (1993) have shown that repeated names are more difficult to be processed compared to the overt pronouns vying for the subject anaphoric position of an entity previously introduced in discourse, creating an effect that it has appointed of "repeated name penalty "(RNP). In turn, Gerlimini-Lezama (2008) tested the same type coreference to expand the theory for the use of the null pronoun in Spanish, which is a pro-drop language, unlike English, and in turn, has shown that, at least this language, null pronouns are more easily processed than repeated names, creating the effect that he named "overt pronoun penalty" (OPP). In PB, RNP has been the subject of discussion among many scholars and quite reaffirmed by Leitão (2005) and colloboraters (Queiroz & Leitão, 2008; Leitão & Simões, 2011, inter alia). Taken together, these studies have corroborated acceptance of the effect of RNP in PB not only in the subject position, but also the object position. However, Maia & Cunha Lima (2011, 2012) presented evidence contradictory to previous studies on the RNP in PB, indicating the occorence of OPP in PB. We work with the hypotheses that the distance has a significant role during processing, giving the name repeated the status of reference expression at the expense of overt and/or null pronouns for both simple subject and composed subjects. The analysis of the experimental results suggest that (i) at the critical region the null pronouns are processed more easily than overt pronouns and repeated names, and (ii) the distance between the antecedent and its referring expression plays no significant role in the coreferential processing. / Nesta dissertação, investigamos como nomes repetidos, pronomes plenos e pronomes nulos são processados quando exercem a função de expressões correferentes em português brasileiro (PB). Gordon, Grosz & Gilliom (1993) comprovaram que os nomes repetidos são mais difíceis de serem processados quando comparados aos pronomes plenos que disputam a posição de sujeito anafórico de uma entidade previamente introduzida no discurso, gerando um efeito por eles nomeado de “Repeated Name Penalty” (RNP). Por sua vez, Gerlomini-Lezama (2008) testou o mesmo tipo de correferência expandindo a teoria para o uso do pronome nulo em espanhol, que é uma língua pro-drop, diferentemente do inglês e, por sua vez, comprovou que, ao menos nesta língua, os pronomes nulos são mais facilmente processados do que nomes repetidos, gerando o efeito por ele nomeado de “Overt Pronoun Penalty” (OPP). Em PB, a RNP tem sido objeto de discussão entre muitos estudiosos e bastante reafirmada por Leitão (2005) e colaboradores (QUEIROZ & LEITÃO, 2008; LEITÃO & SIMÕES, 2011, inter alia). Tomados em conjunto, todos esses estudos têm corroborado a aceitação do efeito da RNP em PB não somente na posição de sujeito, mas também na posição de objeto, sem distanciar o antecedente de sua retomada anafórica. Entretanto, Maia e Cunha-Lima (2011, 2012) encontraram evidências contrárias aos estudos prévios sobre a RNP em PB, indicando a ocorrência da OPP em PB. Trabalhamos com a hipótese de que a distância exerce papel significativo durante o processamento, atribuindo ao nome repetido o status de expressão referencial em detrimento dos pronomes pleno e/ou nulos, tanto para sujeito simples quanto para sujeitos. A análise conjunta dos resultados do experimento sugere que (i) na região crítica, os pronomes nulos são processados mais facilmente do que pronomes plenos e nomes repetidos, e (ii) que a distância entre o antecedente e sua expressão referencial não desempenha papel significativo durante o processamento correferencial.

Page generated in 0.0269 seconds