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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.
221

Desenvolvimento de um algoritmo de escalonamento para rede Foundation Fieldbus / Desenvolvimento de um algoritmo de escalonamento para rede Foundation Fieldbus

Cicillini, Daniele Aparecida 11 October 2007 (has links)
Este trabalho apresenta e implementa um algoritmo de escalonamento para a tecnologia Foundation Fieldbus. O algoritmo denominado FFSMART escalona as mensagens de comunicação cíclica ou periódica entre os dispositivos de campo que estão no barramento fieldbus. Trata-se de um algoritmo de escalonamento pré-run-time, que permite atender às restrições de precedência dos blocos funcionais, personalizando e otimizando o uso dos recursos do sistema. O algoritmo foi implementado na linguagem de programação Visual Basic e sua validação ocorreu em um ambiente real de aplicação através de estratégias de configuração, cujos resultados foram satisfatórios. / This dissertation presents and implements a scheduling algorithm for the Foundation Fieldbus technology. The algorithm named FFSMART schedules cyclic or periodic communication messages among field devices connected to a fieldbus. The FFSMART is a pre-runtime scheduling algorithm, which allows meeting the restrictions of precedence from function blocks, customizing and optimizing the use of the system resources. The algorithm was implemented using the Visual Basic programming language and validated in a real application environment using configuration strategies, and the results were satisfactory.
222

Diseño de propuestas de solución y evaluación técnico-económica para la cimentación de tres edificios de concreto armado de sistema de muros de 4, 6 y 8 pisos situados en un suelo de capacidad portante de 1.01kg/cm2 / Design of solution alternatives and technical-economic evaluation for the foundations of three reinforced concrete buildings with walls system of 4, 6 and 8 floors located in a soil with bearing capacity of 1.01kg/cm2

Li Davelouis, Julio Raúl, Zegarra Chávez, Juan Segundo 16 July 2019 (has links)
Se retirará este documento a solicitud del Sandra Rodriguez Dionisio, Coordinador de carrera de Ingeniería Civil. Fecha de solicitud mediante correo electrónuico 19-09-2019 / La investigación consiste en la evaluación técnico-económica de tres alternativas de cimentación, las cuales son platea de cimentación, sistema de zapatas y micropilotes, estudiadas en tres proyectos situados en un suelo de baja capacidad portante igual a 1.01kg/cm2. Esto con el objetivo de determinar la alternativa de solución más óptima en función a los criterios técnico y económico, teniendo en cuenta que la opción de platea de cimentación es comúnmente la más empleada. En cuanto a los proyectos, estos corresponden a edificios multifamiliares de 4, 6 y 8 pisos, de material de concreto armado, de sistema estructural a base de muros y sin sótanos. Estos ese encuentran situados en un suelo arenoso (SP-SM), sin presencia del nivel freático ni fallas geológicas, perteneciente al distrito de Ica, provincia de Ica, departamento de Ica, Perú. Respecto al diseño de las alternativas de cimentación, estas se rigen bajo las exigencias de las normas de diseño vigentes en el Perú, correspondientes al Reglamento Nacional de Edificaciones (RNE). Asimismo, se utilizaron programas de software como ETABS y SAP2000, para complementar el análisis estructural de los edificios y diseño de las alternativas de cimentación. Posterior al diseño, se realizó la evaluación técnico-económica, proponiendo un plan de ejecución (cronograma) acorde con las características y contexto del proyecto, como también un presupuesto económico para cada caso. Finalmente, mediante un análisis comparativo que contrasta ambos criterios, se concluye la alternativa de cimentación más óptima para cada caso de estudio. / The investigation consists in technical and economic evaluation of foundation alternatives, which are foundation plate, shoe system and micropiles, for three projects located in a low bearing capacity soil of to 1.01kg/cm2. The study objective is determine the best foundation alternative according to technical and economic criteria, taking into account that foundation plate is commonly the most used. Corresponding to the projects, these are multifamily buildings of 4, 6 and 8 floors, of reinforced concrete material, structural system based on walls and without basements. In the same way, these projects are located in a sandy soil (SP-SM), without freatic level presence neither geological fails, located in Ica district, Ica province, Ica department, Peru. On the other hand, according to the foundation alternatives design, these are supported by the requirements of the peruvian design rules “Reglamento Nacional de Edificicaciones” (RNE). In the same way, software programs such as ETABS and SAP2000 were used to complement the study of buildings structural performance and foundation alternatives. After design, the technical-economic evaluation was carried out, proposing an execution plan (schedule) according to the characteristics and context of the projects, and an economic budget for each case. Finally, through a comparative analysis that contrats both criteria, the best foundation alternative por each case is concluded. / Tesis
223

Agency Through Adaptation: Explaining The Rockefeller and Gates Foundation???s Influence in the Governance of Global Health and Agricultural Development

Stevenson, Michael January 2014 (has links)
The central argument that I advance in this dissertation is that the influence of the Rockefeller Foundation (RF) and the Bill and Melinda Gates Foundation (BMGF) in the governance of global health and agricultural development has been derived from their ability to advance knowledge structures crafted to accommodate the preferences of the dominant states operating within the contexts where they have sought to catalyze change. Consequently, this dissertation provides a new way of conceptualizing knowledge power broadly conceived as well as private governance as it relates to the provision of public goods. In the first half of the twentieth-century, RF funds drove scientific research that produced tangible solutions, such as vaccines and high-yielding seed varieties, to longstanding problems undermining the health and wealth of developing countries emerging from the clutches of colonialism. At the country-level, the Foundation provided advanced training to a generation of agricultural scientists and health practitioners, and RF expertise was also pivotal to the creation of specialized International Organizations (IOs) for health (e.g. the League of Nations Health Organization) and agriculture (e.g. the Consultative Group on International Agricultural Research) as well as many informal international networks of experts working to solve common problems. Finally in the neo-liberal era, RF effectively demonstrated how the public-private partnership paradigm could provide public goods in the face of externally imposed austerity constraining public sector capacity and the failure of the free-market to meet the needs of populations with limited purchasing power. Since its inception, the BMGF has demonstrated a similar commitment to underwriting innovation through science oriented towards reducing global health disparities and increasing agricultural productivity in poor countries, and has greatly expanded the application of the Public-Private Partnership (PPP) approach in both health and agriculture. Unlike its intellectual forebear, BMGF has been far more focused on end-points and silver bullets than investing directly in the training of human resources. Moreover whereas RF has for most of its history decentralized its staff, those of BMGF have been concentrated mainly at its headquarters in Seattle. With no operational programs of its own, BMGF has instead relied heavily on external consultants to inform its programs and remains dependent on intermediary organizations to implement its grants. Despite these and other differences, both RF and BMGF have exhibited a common capacity to catalyse institutional innovation that has benefited historically marginalized populations in the absence of structural changes to the dominant global power structure. A preference for compromise over contestation, coupled with a capacity for enabling innovation in science and governance, has resulted in broad acceptance for RF and BMGF knowledge structures within both state and international policy arenas. This acceptance has translated into both Foundations having direct influence over (i) how major challenges related to disease and agriculture facing the global south are understood (i.e. the determinants and viable solutions); (ii) what types of knowledge matters for solving said problems (i.e. who leads); and (iii) how collective action focused on addressing these problems is structured (i.e. the institutional frameworks).
224

An Improved Finite Grid Solution For Plates On Generalized Foundations

Karasin, Abdulhalim 01 January 2004 (has links) (PDF)
In many engineering structures transmission of vertical or horizontal forces to the foundation is a major challenge. As a first approach to model it may be assumed that the foundation behaves elastically. For generalized foundations the model assumes that at the point of contact between plate and foundation there is not only pressure but also moments caused by interaction between the springs. In this study, the exact stiffness, geometric stiffness and consistent mass matrices of the beam element on two-parameter elastic foundation are extended to solve plate problems. Some examples of circular and rectangular plates on two-parameter elastic foundation including bending, buckling and free vibration problems were solved by the finite grid solution. Comparison with known analytical solutions and other numerical solutions yields accurate results.
225

The Rockefeller Foundation and modern medical education in China, 1915-1951 /

Ma, Qiusha. January 1995 (has links)
Thesis (Ph. D.)--Case Western Reserve University, 1995. / Includes bibliographical references (leaves 318-337). Also issued online.
226

Serviceability and safety in the design of rigid inclusions and combined pile-raft foundations / Calcul des déplacements et sécurité dans le dimensionnement des fondations mixtes et inclusions rigides

Bohn, Cécilia 30 September 2015 (has links)
Les inclusions rigides sont un concept récent développé dans le prolongement des fondations mixtes, avec un matelas de transfert de charges entre les colonnes et la structure. Des méthodes de calculs et des concepts de sécurité existent pour ces systèmes combinés, notamment en France où le module pressiométrique mesuré et les recommandations ASIRI (IREX 2012) pour les inclusions rigides sont utilisés. Le dimensionnement classique des pieux basé sur une simple vérification de la portance des colonnes isolées ne peut pas être appliqué à ces systèmes combinés. Les tassements peuvent être plus importants du fait de la part significative de charge reprise par le sol. Le présent travail est une contribution au développement des méthodes de calcul et de dimensionnement en déplacement (préconisé par l'Eurocode 7, EN 1997-1 2004) pour les systèmes combinés sous charge verticale, en particulier au niveau international où des mesures in situ de module de sol ne sont généralement pas disponibles. Les éventuelles particularités de ces systèmes, notamment la sensibilité de colonnes non renforcées de petit diamètre, devaient également être examinées. La méthode de transfert de charge (“load transfer method”, LTM) est identifiée comme un outil d'ingénieur particulièrement adapté au calcul des systèmes combinés présentant une géométrie relativement simple. L'interaction sol-colonne en frottement et en pointe est définie par des courbes de transfert de charge (ou courbes “t-z” et “q-z”). Les méthodes en milieu continu comme la méthode des éléments finis sont à réserver en général aux cas complexes. Le comportement non-linéaire des semelles est examiné sur la base de mesures obtenues dans la littérature. Cette étude aboutit à la proposition d'une courbe charge-tassement hyperbolique pour les semelles. Cette courbe de mobilisation est définie de sorte qu'il y ait concordance avec la méthode linéaire habituelle pour un tiers de la charge ultime de la semelle. Le comportement de pieux isolés est étudié avec de nombreux essais de chargement instrumentés et non-instrumentés pour différents types de pieux et de sol. Une alternative aux courbes de transfert de charge selon Frank et Zhao (1982), basées sur le module pressiométrique, est recherchée. Des courbes de transfert de charge de type racine cubique et hyperbolique sont proposées pour tous types de pieux et de sol. La raideur des courbes proposées dépend d'une bonne estimation des valeurs ultimes de frottement et de résistance de pointe. Au contraire, la raideur initiale des courbes de Frank et Zhao est entièrement définie par le module pressiométrique, ce qui permet d'éviter des erreurs en termes de raideur. Les courbes de mobilisation proposées pour les fondations superficielles et pour les pieux sont combinées et étendues au cas des systèmes combinés. Cette méthode est implémentée comme option LTM dans le programme KID (Keller company 2015). Les prévisions avec le modèle proposé sont en très bonne adéquation avec les mesures effectuées sur 3 sites documentés dans la littérature. Une étude paramétrique montre une transition continue entre la fondation mixte et les inclusions rigides et une possibilité d'optimisation avec une diminution significative des efforts dans les colonnes et dans la fondation superficielle si un matelas est utilisé. En complément, une comparaison avec des calculs en éléments finis en 3D dans un cas théorique de semelle sur colonnes confirme que la méthode de transfert de charge développée est très performante pour des géométries simples. Une analyse de sensibilité est effectuée avec des modèles éléments finis axisymmétriques et 3D avec Plaxis (2013, 2014). Les imperfections géométriques ont principalement une incidence sur l'intégrité structurelle des colonnes non-armées de faible diamètre. Cependant, ces effets sont atténués dans les systèmes combinés en comparaison avec la colonne isolée du fait des possibilités de redistribution des charges dans le système / Rigid inclusions represent a further development of combined pile-raft foundations, comprising a load transfer platform between the columns and the structure. Calculation methods and design concepts are available for such combined systems in particular in France, based on measured pressuremeter modulus values and on the French recommendations ASIRI for rigid inclusions (IREX 2012). The conventional pile design consisting only of a bearing capacity check for the individual column cannot be applied to such combined systems. The expected settlements may be larger due to a significant load proportion supported by the soil. The present work contributes to the development of displacement-based calculation methods (advocated by the Eurocode 7, EN 1997-1 2004) and design methods for combined systems under vertical loads, in particular on an international level where in general no in situ soil modulus values are measured. Possible particularities of such systems, like the sensitivity of unreinforced small-diameter columns, also had to be investigated. The load transfer method (LTM) is identified as a straightforward engineering tool for the calculation of combined systems with relatively simple geometries. The soil-column interaction in terms of skin friction and tip resistance is described by deformation-dependent load transfer curves (or “t-z” and “q-z” curves). Continuum methods like the finite element method should be preferred only for complex cases in general. The non-linear load-settlement behaviour of single footings up to failure is analysed based on measurements given in the literature. This yields the proposal of a hyperbolic load-settlement curve for footings. This mobilization curve is defined in a way to match the linear usual method for one third of the footing ultimate load. The behaviour of single piles is investigated based on numerous available instrumented and non-instrumented pile load tests with different pile and soil types. A reliable alternative to the load transfer curves after Frank and Zhao (1982), which are based on the pressuremeter modulus, is sought. Cubic root and hyperbolic axial load transfer curves are proposed for all pile and ground types. The stiffness accuracy of the proposed curves depends on an accurate estimation of the ultimate skin friction and tip resistance values. On the contrary, the initial stiffness of the Frank and Zhao curves is fully described by the pressuremeter modulus, avoiding thus errors in the stiffness. The proposed mobilization curves for the shallow and pile foundation behaviours are combined and extended for all combined systems. The proposed method is implemented as the LTM option into the software KID (Keller company 2015). The prediction with the developed model matches very well the measurements made for 3 different cases from the literature. A parametric study shows a smooth transition between the combined pile-raft foundation case and the rigid inclusion case and a potential for optimisation with a significant reduction of the internal forces in the columns and in the rigid slab when a load transfer platform is used. In addition, a comparison with 3D finite element calculations for a theoretical footing case with columns confirms that the developed load transfer method is very reliable for simple geometries. Sensitivity investigations using the axisymmetric and 3D finite element method with Plaxis (2013, 2014) are performed. Geometrical imperfections impact mainly the structural integrity of small-diameter unreinforced columns. However, these effects are reduced in combined systems compared to the single column case due to the possibility of redistribution of the loads within the system
227

Ferramenta de simulação para projeto, avaliação e ensino de redes Fieldbus / Simulation tool for project, evaluation and teaching of Fieldbus systems

Dennis Brandão 06 July 2005 (has links)
Ferramentas de simulação de barramentos de comunicação de chão de fábrica (fieldbuses) têm aplicação industrial durante a fase de projeto de malhas de controle, pois permitem a prévia avaliação do desempenho de tais malhas bem como o treinamento de operadores do sistema de controle. Este trabalho descreve uma ferramenta de simulação de fieldbus com foco na camada de aplicação de blocos funcionais Foundation Fieldbus que preenche os requisitos acima citados em uma plataforma única e autônoma em relação a fabricantes do sistema de controle e, para além disso, tem aplicação no ambiente industrial por usuários de fieldbus como uma ferramenta no desenvolvimento de blocos funcionais \"customizados\", bem como no ambiente acadêmico como ferramenta didática para ensino de sistemas de controle distribuídos. / Fieldbus simulation tools are used in the industry during the planning stages of control network implementations since they allow for a pre-evaluation of the network\'s performance as well as providing a training environment for the control systems operators. This thesis describes a fieldbus simulation tool focused on the Foundation Fieldbus functional blocks application layer that meets the requirements mentioned above within a single vendor independent platform. Additionally, the tool can be used by industrial fieldbus users developing custom functional blocks and, in an academic environment, as an application for teaching distributed control systems.
228

Laboratório remoto para ensino a distância de sistemas de controle distribuído / Web laboratory to networked control systems distance learning

Eduardo André Mossin 26 February 2007 (has links)
Frente a abrangente presença da internet no ambiente acadêmico e residencial, a literatura relata, na última década, um número crescente de experiências de ensino a distância na área de automação e controle industrial, nas quais desde procedimentos teóricos até aulas práticas podem ser realizados através de acesso remoto. Neste contexto, este trabalho apresenta o estado da arte sobre as experiências acadêmicas no emprego de laboratórios on-line relacionados à teoria de controle e introduz uma nova proposta de arquitetura de acesso remoto, que será aplicada ao ensino de sistemas de controle distribuídos via rede de campo no protocolo FOUNDATION Fieldbus em ambiente simulado. / Due to the increasing presence of the internet in the academic and residential environment, the literature shows an increasing number of experiences of distance learning in the automation and industrial control area in the last decade, in which theoretical procedures as well as practical lessons can be carried out through remote access. In this context, this dissertation presents a brief survey on the academic experiences in the application of on-line laboratories and introduces a new proposal of remote access architecture that will be applied on a distance learning experience in the networked control systems area based on the FOUNDATION Fieldbus protocol using a simulated environment.
229

Desenvolvimento de um algoritmo de escalonamento para rede Foundation Fieldbus / Desenvolvimento de um algoritmo de escalonamento para rede Foundation Fieldbus

Daniele Aparecida Cicillini 11 October 2007 (has links)
Este trabalho apresenta e implementa um algoritmo de escalonamento para a tecnologia Foundation Fieldbus. O algoritmo denominado FFSMART escalona as mensagens de comunicação cíclica ou periódica entre os dispositivos de campo que estão no barramento fieldbus. Trata-se de um algoritmo de escalonamento pré-run-time, que permite atender às restrições de precedência dos blocos funcionais, personalizando e otimizando o uso dos recursos do sistema. O algoritmo foi implementado na linguagem de programação Visual Basic e sua validação ocorreu em um ambiente real de aplicação através de estratégias de configuração, cujos resultados foram satisfatórios. / This dissertation presents and implements a scheduling algorithm for the Foundation Fieldbus technology. The algorithm named FFSMART schedules cyclic or periodic communication messages among field devices connected to a fieldbus. The FFSMART is a pre-runtime scheduling algorithm, which allows meeting the restrictions of precedence from function blocks, customizing and optimizing the use of the system resources. The algorithm was implemented using the Visual Basic programming language and validated in a real application environment using configuration strategies, and the results were satisfactory.
230

Uma estratégia em redes Fieldbus usando controle adaptativo por modelo de referência aplicada a sistemas complexos / not available

Elenilton Teodoro Domingues 10 November 2003 (has links)
A crescente complexidade do controle dos processos industriais vem exigindo sistemas de controle cada vez mais precisos, confiáveis e versáteis. No sentido de atender a estas exigências, algoritmos diversos de controle e estimação, tais como: técnicas de controle adaptativas, preditivas, estimação paramétrica, filtros de Kalman, observação de estados, etc. têm sido desenvolvidas, simuladas e implementadas com relativa facilidade nos modernos sistemas digitais. Este trabalho propõe uma estratégia de controle em redes Fieldbus usando controle adaptativo por modelo de referência através de variáveis de estado, para resolver sistemas complexos. O algoritmo de controle proposto é composto por um observador de estados trabalhando em conjunto com um esquema de controle adaptativo por modelo de referência. As malhas de controle no Fieldbus consistem em um conjunto de blocos funcionais padrões existentes, conectados aos novos blocos funcionais propostos e desenvolvidos de acordo com as especificações da norma Fieldbus Foundation. Este algoritmo de controle realiza os cálculos de maneira distribuída entre os dispositivos da rede Fieldbus, implicando em várias vantagens, tais como: a) perda do supervisório não implica na perda do algoritmo de controle, b) menor tráfego de dados na rede, c) algoritmo de controle que não depende do tempo de processamento do computador. Os resultados dos testes obtidos são apresentados e demonstraram um alto grau de precisão, destacando-se a estabilidade e aplicabilidade do algoritmo proposto. / The rising complexity of the industrial control processes has been claiming more and more accurate, reliable and versatile control systems. Attempting to satisfy this demand, several control and estimation systems algorithms, such as adaptive and predictive techniques, parametric estimation, Kalman filtering, state observation, have been designed, simulated and implemented with relative easiness in the modern digital systems. This work proposes a new control strategy in Fieldbus networks, using adaptive control techniques through state variables, to solve complex systems. The proposed control algorithm is based on an states observer concurrently working with a reference model adaptive control scheme. The modified Fieldbus network consists of a set of standard function blocks, connected to the proposed new function blocks. These new function blocks comply with the specifications of the Fieldbus Foundation norm. This control algorithm accomplishes its calculation in a distributed way among the fieldbus devices. This operating feature results in some advantages, such as: any failure in the supervisory system does not imply in the loss of the control algorithm, b) a lower data transmission in the network, c) control algorithm that does not depend on the processing time of the computer. The obtained results corroborate with the expected advantages of the proposed algorithm, in terms of high degree of accuracy, stability and applicability.

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