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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.
11

Dynamic condensation, decomposition and optical properties of Cr2O3-dissolved TiO2 with rutile/post-rutile structures

Chen, Chun-han 15 July 2010 (has links)
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12

Systematic Structure Synthesis of Distillation-Based Separation Processes / 蒸留を基軸とした分離プロセスの系統的構造合成手法

Takase, Hiroshi 26 March 2018 (has links)
京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第21130号 / 工博第4494号 / 新制||工||1698(附属図書館) / 京都大学大学院工学研究科化学工学専攻 / (主査)教授 長谷部 伸治, 教授 大嶋 正裕, 教授 佐野 紀彰 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM
13

Heterotopia: Loose Space For an Edge City

Babii, Volodymyr 26 January 2017 (has links)
In the beginning of my research I focused on transformations of the urban leftover and void space found in between buildings, street networks, parks or other institutionalized public spaces into urban places of character. By studying the spatial qualities of different places and their relation to human activities in those places I came up with the main question of my thesis: Can a space be designed loose and/or can it be loosened by design? The concept of “heterotopia”, as described by Michel Foucault in his essay “Of Other Spaces: Utopias and Heterotopias”, is a place functioning in nonhegemonic conditions, the place of “otherness” that has more layers of meaning than meet the eye. That concept proved to be the best description and the bounding frame of the design part of my research. / Master of Science / This Urban Design thesis explores questions of complexity and layering in the structure of the city. The places that lack social and structural richness are often perceived as dull and absent of character. My questions are mainly focused on how this character can be introduced and what makes space a place. The main body of this study is conceptual graphical research on how, when and where the imaginary place can approximate and meet reality creating a type of city very different from the traditional image. This concept was intended to explore how the city can be made radically different without being a utopia or dystopia in its essence.
14

Comparative study of different methods for superstructure-foundation interactions

Sharma, Prakriti 04 January 2022 (has links)
Bridge failures in the past decade due to structural deficiencies demonstrated the clear need for a review of the current bridge analysis approaches. This study focuses on pile-supported bridges under predominantly static loading. A critical review of the current analysis approaches was performed. It was concluded that in the absence of an onerous iteration process, the current approaches often produce inaccurate and, in many cases, unsafe results since the interactions between superstructure and foundation are not fully considered. To address the inherent limitations of the current approaches, a computer program [Soil Spring Module (SSM) 2.0] was developed as a part of the study. SSM 2.0 can be used in conjunction with a frame analysis program to capture nonlinear load transfer from foundation elements to soil in different directions simultaneously. STAAD.Pro was selected for demonstration in this study. Using SSM 2.0 and STAAD.Pro, this study proposes a new analysis approach using the Integrated Analysis Process (IAP). The same methodology can be applied in other frame analysis programs. Kansas Bridge 45 was selected as a case study. Using the IAP approach, a series of integrated analyses including all superstructure elements (e.g., deck, girders and piers) and all foundation elements (e.g., pile caps and piles) were performed on Kansas Bridge 45 for different soil types and properties. Different from the conventional approaches, the full interactions between superstructure and foundation were considered simultaneously in a single analysis using the IAP approach. The analysis results from the IAP approach and the conventional approaches were examined. The advantages of the IAP approach were identified. Comparing to the conventional approaches in current practice, the proposed IAP approach does not involve crude assumptions or intensive iterations. Using the IAP approach, design engineers can complete structural and foundation analysis of pile-supported bridges with good accuracy in a timely manner. The same methodology can potentially be applied to other structure types. / Graduate / 2022-12-15
15

Conception and optimization of supercritical CO2 Brayton cycles for coal-fired power plant application / Conception et optimisation du cycle de Brayton au CO2 supercritique dans l’application des centrales à charbon

Zhao, Qiao 15 May 2018 (has links)
L'amélioration des systèmes énergétiques est considérée comme un levier technologique pour répondre aux défis liés à la croissance de la demande d’électricité et des émissions des gaz à effet de serre. Les futures centrales devraient présenter une intégration thermique plus flexible et des sources de chaleur mixtes possibles. Une des solutions fiables consiste à utiliser un cycle de Brayton au CO2 supercritique (CO2-SC), un tel cycle à haut rendement est théoriquement prometteur pour les applications nucléaires, fossiles et solaires thermiques. Un des principaux obstacles au déploiement du cycle de Brayton au CO2-SC est de justifier sa faisabilité, sa viabilité et son potentiel à l’échelle industrielle. Dans ce contexte deux axes de recherche ont été identifiées : • Une sélection rigoureuse de l’équation d’état qui permet de représenter les propriétés d’intérêt du CO2-SC. • Une nouvelle méthodologie pour l’optimisation des centrales électriques, permettant de sélectionner automatiquement le procédé optimal parmi une grande quantité de configurations possibles (dénomme superstructure). Les résultats de la première partie de cette thèse mettent en lumière que l’équation de SW est pertinente pour limiter l’impact de l’imprécision de l’équation d’état sur le dimensionnement du procédé. Dans cette thèse, un simulateur de procédé commercial, ProSimPlus a été combiné avec un solveur type évolutionnaire (MIDACO) afin d’effectuer des optimisations superstructure. Premièrement, le critère d’optimisation est de maximiser le rendement énergétique du procédé. Dans un deuxième temps, on cherche simultanément à minimiser les coûts du procédé. Pour ce faire, des fonctions de coût internes à EDF ont été utilisées afin de permettre l’estimation des coûts d'investissement (CAPEX), des dépenses opérationnelles (OPEX) et du coût actualisé de l'électricité (LCOE) / Efficiency enhancement in power plant can be seen as a key lever in front of increasing energy demand. Nowadays, both the attention and the emphasis are directed to reliable alternatives, i.e., enhancing the energy conversion systems. The supercritical CO2 (SC-CO2) Brayton cycle has recently emerged as a promising solution for high efficiency power production in nuclear, fossil-thermal and solar-thermal applications. Currently, studies on such a thermodynamic power cycle are directed towards the demonstration of its reliability and viability before the possible building of an industrial-scale unit. The objectives of this PhD can be divided in two main parts: • A rigorous selection procedure of an equation of state (EoS) for SC-CO2 which permits to assess influences of thermodynamic model on the performance and design of a SC-CO2 Brayton cycle. • A framework of optimization-based synthesis of energy systems which enables optimizing both system structure and the process parameters. The performed investigations demonstrate that the Span-Wagner EoS is recommended for evaluating the performances of a SC-CO2 Brayton cycle in order to avoid inaccurate predictions in terms of equipment sizing and optimization. By combining a commercial process simulator and an evolutionary algorithm (MIDACO), this dissertation has identified a global feasible optimum design –or at least competitive solutions– for a given process superstructure under different industrial constraints. The carried out optimization firstly base on cycle energy aspects, but the decision making for practical systems necessitates techno-economic optimizations. The establishment of associated techno-economic cost functions in the last part of this dissertation enables to assess the levelized cost of electricity (LCOE). The carried out multi-objective optimization reflects the trade-off between economic and energy criteria, but also reveal the potential of this technology in economic performance.
16

Analyse thermo-économique d'un système de dessalement par thermocompression de vapeur et conception de l'éjecteur

Samaké, Oumar January 2016 (has links)
L’objectif de cette thèse est de présenter les travaux d’une analyse thermo-économique d’un système de dessalement par distillation dans l’optique de revaloriser les pertes thermiques industrielles. Les rejets en question sont ceux d’un moteur Diesel utilisé dans une centrale de production d’électricité. Premièrement, une étude préliminaire est faite en utilisant un modèle boite noire. L’optimisation des fonctions objectives de ce modèle a permis de déterminer les paramètres de conception. Ensuite un nouveau modèle d’éjecteur distinct des deux modèles classiques utilisés en thermodynamique (à pression et à section constante) est développé. Les performances des procédés de détente et de compression dans cet éjecteur sont calculées en appliquant un rendement polytropique comme dans les turbomachines. La méthode développée a permis de déterminer toutes les dimensions de l’éjecteur ainsi que la position de l’onde de choc. Enfin une analyse détaillée du système de dessalement est faite pour déterminer le nombre d’effets ou cellules et les conditions qui permettent de satisfaire les conditions optimales obtenues lors de l’analyse préliminaire. L’analyse thermodynamique se base sur un tout nouveau modèle mathématique qui permet de simuler à la fois les deux configurations les plus utilisées en dessalement. De plus, une analyse thermo-économique basée sur l’exergo-économie a permis de calculer le coût de production et les investissements nécessaires.
17

Síntese ótima de processos não isotérmicos de tratamento de efluentes. / Optimal synthesis of non-isothermal wastewater treatment processes.

Graciano, José Eduardo Alves 24 February 2012 (has links)
As metodologias para a síntese de processos, baseadas em otimização de superestruturas, mostram-se mais poderosas do que as baseadas no projeto em heuríticas, já que levam em consideração as inúmeras possibilidades de construção do processo. É pratica comum a utilização de modelos simplificados (como modelos de rendimento), na representação dos equipamentos dentro destas superestruturas, uma vez que a utilização de modelos fenomenológicos tornar-se-ia inviável, devido aos tempos computacionais e à dificuldade técnica de se programar os módulos e propriedades termodinâmicas de um simulador comercial, dentro de uma plataforma de otimização como o GAMS. Modelos com alta precisão, que não requerem grandes tempos computacionais, reduzidos ou de superfície de resposta, aproximam modelos fenomenológicos e podem ser introduzidos em problemas de síntese, obtendo soluções mais precisas. Neste trabalho, foram construídos modelos reduzidos para dois processos comumente encontrados em sistemas de tratamento de efluentes de refinarias de petróleo: uma torre de resfriamento e um stripper de vapor. Os dados utilizados para a correlação dos modelos reduzidos foram gerados, através da simulação de modelos semi-fenomenológicos ou fenomenológicos destes equipamentos. É proposta uma metodologia original para gerar modelos reduzidos, que diferentemente dos trabalhos anteriores em que se utilizam modelos reduzidos tipo caixa preta, emprega-se um modelo reduzido tipo caixa cinza para a representação da coluna de stripper, o que aumenta a capacidade de correlação do modelo ao conjunto de dados, resultando em menores erros de predição. Dois tipos clássicos de modelos reduzidos foram utilizados dentro dos modelos caixa-cinza: um modelo baseado em redes neurais e um modelo polinomial. Ambos mostraram-se capazes de representar o modelo fenomenológico com pequenos erros e permitindo resolver o problema de síntese em um tempo computacional razoável (da ordem de 10 segundos). Nota-se também que são obtidas várias soluções ótimas locais que diferem ligeiramente de acordo com a abordagem utilizada, mas que qualitativamente correspondem a um mesmo conjunto de soluções. / The superstructure optimization-based methodologies for process synthesis can be more powerful than the heuristic based methodologies, because they cope the many possibilities in order to design the process. It is common practice to use simplified models (efficiency-based models), in the representation of equipment in the superstructures, because the use of phenomenological models would be unfeasible due the high computational time and the technical difficulties in order to program module and thermodynamics properties packages of commercial simulators, into an optimization platform as GAMS. High accuracy models, which do not require large computational time, can be obtained using different types of surrogate or response surface, approximate phenomenological models of the system and can be introduced into the synthesis problems, leading to more precise solutions. In this work, surrogate models were built for two processes usually found in water treatment networks in petroleum refineries: a cooling tower and a steam stripper. The data sets used for fitting the surrogate model were generated by the semi-phenomenological or the first principles model of those equipment. An original methodology for generating surrogate model is proposed that differently of previous works (which make use of black box surrogate models) uses gray box models to represents de stripper column. This approach improves the correlation capacity of the surrogate model to the set data and reduces the prediction errors. Finally, two classic surrogate models were used inside the gray-box models: a neural network based model and a polynomial model. The results showed that both are able to represent the phenomenological model with small errors to solve the synthesis problem in a short computational time (which not exceed in a magnitude of 10 seconds). It is noticed also that many local solutions are obtained, these differ slightly depending on the approach used, but qualitatively represent the same set of solutions.
18

Efeito da superestrutura sobre a resistência longitudinal de embarcações de pequeno porte: aplicação e análise estrutural para um navio militar da Marinha Colombiana. / Effect of the superstructure on the longitudinal resistance of the small vessel: application and structural analysis for Colombian Naval vessel.

Mojica Valero, Carlos Alberto 19 June 2008 (has links)
O propósito do presente trabalho é desenvolver a avaliação estrutural de um navio \"Nodriza\" de pequeno porte de aplicação militar e cujo projeto inicial foi orientado à navegação em águas abrigadas com restrições de calado. Porém, requisitos e necessidades afetando a concepção inicial do projeto obrigam este a efetuar percursos em águas profundas com possibilidade de experimentar ciclos de onda. A avaliação estrutural pretende determinar o nível de influência da superestrutura sobre a resistência longitudinal do navio considerando-o submetido a esforços solicitantes próprios de águas não abrigadas. As limitações geradas pelas formas e proporções do navio Nodriza, que não permitem implementar de forma direta as regras de Sociedades Classificadoras para a avaliação estrutural em águas profundas, obriga ao uso de cálculos diretos para sua aprovação. Uma análise mediante o uso de elementos finitos, modelando o navio com e sem participação da superestrutura, permite determinar como esta representa uma significativa influência sobre a resistência longitudinal e tensões finais dos membros principais e membros de suporte, quando é considerada dentro da análise estrutural. Igualmente, implementam-se procedimentos determinísticos propostos pelas regras de sociedades classificadoras para navios convencionais, na procura de estabelecer a conveniência ou não da sua aplicação como método de aproximação para uma avaliação estrutural desta classe de navio militar, cujas características tornam dele um caso particular de análise. / The objective of the present work is to conduct a structural evaluation of the small size, military vessel Nodriza which has been designed for navigation in sheltered waters with draft restrictions. However, new requirements and changes in the operation of this vessel forced deep water navigation with the possible action of wave loading. The structural evaluation seeks to determine the effects of the superstructure on the longitudinal structural resistance for the vessel. Since the geometry and overall dimensions of the ship are not covered by the structural rules of the Classification Societies, a numerical analyses based on the finite element method is conducted for a full model of the vessel. The numerical analyses demonstrate the strong effect of the superstructure on the longitudinal resistance which yields reduced stress levels in primary structural members. The work provides a compelling support to use more refined procedures in the structural design of non-conventional small-sized vessels.
19

Polyfázový strukturní vývoj rozhraní suprastruktury a infrastruktury v orogenních zónách / Polyphase structural evolution of superstructure and infrastructure in orogenic zones

Peřestý, Vít January 2012 (has links)
Polyphase structural evolution of superstructure and infrastructure in orogenic zones Proterozoic basement rocks of the Teplá-Barrandian Unit (TBU) are affected by two main tectono-metamorphic events. The central and SW part of the TBU is a well-preserved relict of Cadomian episode. On the other hand, the western margin of the TBU shows superposition of polyphase early-varicsan deformation and metamorphism onto the pre- variscan fabric. The Střela river profile in the northern part of Teplá Crystalline Complex (TCC) exposes a continuous crustal section through western margin of the TBU from the low-grade phyllites (near biotite izograd) in the east to the high-grade rocks of kyanite zone at the contact with high-pressure Mariánské-Lázně Complex (MLC). Three main deformation events were distinguished in the studied area and the cross-section is interpreted as a fossil (devonian) suprastructure-infrastructure transition zone preserved in the carboniferous TBU superstructure. The oldest pre-variscan D1 phase produced flat-lying metamorphic foliation showing normal metamorphic zonation from the very low-grade in the upper part to at least garnet zone in the structurally lower part. Large scale upright folding of prevariscan foliation S1 occurred during early-variscan D2 event. Tight F2 folds were...
20

Síntese ótima de processos não isotérmicos de tratamento de efluentes. / Optimal synthesis of non-isothermal wastewater treatment processes.

José Eduardo Alves Graciano 24 February 2012 (has links)
As metodologias para a síntese de processos, baseadas em otimização de superestruturas, mostram-se mais poderosas do que as baseadas no projeto em heuríticas, já que levam em consideração as inúmeras possibilidades de construção do processo. É pratica comum a utilização de modelos simplificados (como modelos de rendimento), na representação dos equipamentos dentro destas superestruturas, uma vez que a utilização de modelos fenomenológicos tornar-se-ia inviável, devido aos tempos computacionais e à dificuldade técnica de se programar os módulos e propriedades termodinâmicas de um simulador comercial, dentro de uma plataforma de otimização como o GAMS. Modelos com alta precisão, que não requerem grandes tempos computacionais, reduzidos ou de superfície de resposta, aproximam modelos fenomenológicos e podem ser introduzidos em problemas de síntese, obtendo soluções mais precisas. Neste trabalho, foram construídos modelos reduzidos para dois processos comumente encontrados em sistemas de tratamento de efluentes de refinarias de petróleo: uma torre de resfriamento e um stripper de vapor. Os dados utilizados para a correlação dos modelos reduzidos foram gerados, através da simulação de modelos semi-fenomenológicos ou fenomenológicos destes equipamentos. É proposta uma metodologia original para gerar modelos reduzidos, que diferentemente dos trabalhos anteriores em que se utilizam modelos reduzidos tipo caixa preta, emprega-se um modelo reduzido tipo caixa cinza para a representação da coluna de stripper, o que aumenta a capacidade de correlação do modelo ao conjunto de dados, resultando em menores erros de predição. Dois tipos clássicos de modelos reduzidos foram utilizados dentro dos modelos caixa-cinza: um modelo baseado em redes neurais e um modelo polinomial. Ambos mostraram-se capazes de representar o modelo fenomenológico com pequenos erros e permitindo resolver o problema de síntese em um tempo computacional razoável (da ordem de 10 segundos). Nota-se também que são obtidas várias soluções ótimas locais que diferem ligeiramente de acordo com a abordagem utilizada, mas que qualitativamente correspondem a um mesmo conjunto de soluções. / The superstructure optimization-based methodologies for process synthesis can be more powerful than the heuristic based methodologies, because they cope the many possibilities in order to design the process. It is common practice to use simplified models (efficiency-based models), in the representation of equipment in the superstructures, because the use of phenomenological models would be unfeasible due the high computational time and the technical difficulties in order to program module and thermodynamics properties packages of commercial simulators, into an optimization platform as GAMS. High accuracy models, which do not require large computational time, can be obtained using different types of surrogate or response surface, approximate phenomenological models of the system and can be introduced into the synthesis problems, leading to more precise solutions. In this work, surrogate models were built for two processes usually found in water treatment networks in petroleum refineries: a cooling tower and a steam stripper. The data sets used for fitting the surrogate model were generated by the semi-phenomenological or the first principles model of those equipment. An original methodology for generating surrogate model is proposed that differently of previous works (which make use of black box surrogate models) uses gray box models to represents de stripper column. This approach improves the correlation capacity of the surrogate model to the set data and reduces the prediction errors. Finally, two classic surrogate models were used inside the gray-box models: a neural network based model and a polynomial model. The results showed that both are able to represent the phenomenological model with small errors to solve the synthesis problem in a short computational time (which not exceed in a magnitude of 10 seconds). It is noticed also that many local solutions are obtained, these differ slightly depending on the approach used, but qualitatively represent the same set of solutions.

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