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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.
71

In Vitro Binding and Transport Regulation by Endothelial Cells: Preliminary Studies looking at FIX and IGF-I

Sutton, Amanda 13 April 2005 (has links)
Endothelial cells separate the bloodstream from the underlying tissue and play a crucial role in vascular homeostasis. They also form an important barrier for vascular drug delivery. This thesis contains preliminary studies targeted at understanding the mechanisms of binding and transport across endothelial cells cultured in vitro. Specifically, the first study investigates how the recombinant source of Factor IX (FIX), a blood coagulant protein used in the treatment of Hemophilia B, impacts surface ligand binding (FIX to its specific receptors) to bovine aortic endothelial cells (BAECs). Competitive binding experiments between 125I-FIX and FIX were undertaken to quantify the interaction of recombinant and transgenic FIX with BAECs and human collagen IV and determine if there was a measurable difference in binding affinity. Results indicate limited specific binding of 125I-FIX to BAECs and no binding to human collagen IV. Concrete conclusions were not drawn from this data due to technical issues during the experimental process. The second study investigates insulin-like growth factor-I (IGF-I) transport across both BAEC and MAC-T cells, a mammary epithelial cell line, cultured on tissue culture inserts. IGF-I is a circulatory growth factor implicated in the regulation of cell division and tissue proliferation. Competitive binding experiments between 125I-IGF-I and unlabeled protein (IGF-I, Y60L-IGF-I, a mutant of IGF-I, and IGF Binding Protein-3 (IGFBP-3)) were undertaken to quantify the binding and transport of IGF-I under various experimental conditions. Results confirmed earlier work from the Williams' laboratory indicating that 125I-IGF-I transport was enhanced by incubation with its non-receptor-binding analog, Y60L-IGF-I, but cell surface associated 125I-IGF-I was decreased by its presence. Other studies were undertaken but conclusive results could not be drawn. / Master of Science
72

The Mississippi River Delta Basin and Why We are Failing to Save its Wetlands

Boudreaux, Lon, Jr. 08 August 2007 (has links)
Every thousand years or so, when the Mississippi River's sediment load lengthened and blocked the River’s route to the Gulf of Mexico, the mother stream changed course completely, finding a shorter route to the sea. Then, it built a new delta, thus spreading the gift of land creation along a wide coastline and creating the bayou region of Louisiana. However, this ancient, natural process was gradually halted by the arrival of man who settled across the River's natural floodplain (delta) and constructed levees and other structures to control the great Mississippi River. Since the 1930s, the Mississippi River Delta Basin and the coast of Louisiana have been literally losing ground. The decline of this environment is now affecting, and will continue to affect, our nation's economy, infrastructure, culture, and safety. Moreover, efforts to fix this problem are not working. My research and this thesis will address the issue of how plans without action have appeased Louisianans while the nation looses vital wetlands daily.
73

Logística de distribuição com restrições de reabastecimento : um estudo de caso em uma empresa de laticínios

Lima, Rayra Brandão de 14 December 2015 (has links)
Submitted by Caroline Periotto (carol@ufscar.br) on 2016-09-19T18:29:26Z No. of bitstreams: 1 DissRBL.pdf: 2233937 bytes, checksum: 7a73fb1e4ba8f340cb8d4bdf4e8153d4 (MD5) / Approved for entry into archive by Marina Freitas (marinapf@ufscar.br) on 2016-09-20T18:01:34Z (GMT) No. of bitstreams: 1 DissRBL.pdf: 2233937 bytes, checksum: 7a73fb1e4ba8f340cb8d4bdf4e8153d4 (MD5) / Approved for entry into archive by Marina Freitas (marinapf@ufscar.br) on 2016-09-20T18:05:15Z (GMT) No. of bitstreams: 1 DissRBL.pdf: 2233937 bytes, checksum: 7a73fb1e4ba8f340cb8d4bdf4e8153d4 (MD5) / Made available in DSpace on 2016-09-20T18:05:28Z (GMT). No. of bitstreams: 1 DissRBL.pdf: 2233937 bytes, checksum: 7a73fb1e4ba8f340cb8d4bdf4e8153d4 (MD5) Previous issue date: 2015-12-14 / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / The Brazilian market for dairy products is highly competitive and is still dominated by multinationals. Thus, it's essential that the national companies to invest in operational efficiency in order to compete successfully. Therefore, this research focuses in a small dairy company of the state of Pará, whose distribution system requires periodic stops for battery recharging. Moreover, the system is characterized by multiple periods and multiple time windows. To our knowledge, so far the literature hasn't presented a directly applicable methodology for the treatmeant of the application with similar characteristics. Therefore, aiming to provide more effective solutions than the ones in practice, a mixed integer linear model was developed to describe (and solve) the problem as a vehicle routing problem with time window constraints, multi-period and periodic stops for recharging. The results showed that the model adequately describes the distribution of the company, and the obtained solutions are better than those currently practiced. Furthermore, the model shows good performance within 3600 seconds of computational time for instances of 40 customers, 1 vehicle and 1 and 2 recharging stations. Aiming to tackle with larger examples, we developed a mathematical programming heuristic Relax-and-Fix to solve the model. It was also tested adapting a similar model present in the literature in order to analyze if the relaxation of some restrictions have a positive impact on the quality of the solutions. Finally, we propose a location-distribution model for recharging stations in order to examine whether the addition of new stations produce significant improvements in the solutions. / O mercado brasileiro de laticínios é altamente competitivo, sendo ainda dominado por multinacionais. Desta forma, é indispensável que as empresas nacionais invistam na eficiência operacional de forma a concorrer satisfatoriamente neste mercado. À vista disso, o foco desta pesquisa é uma pequena empresa de laticínios do Estado do Pará, cujo o sistema de distribuição a pontos de venda possui a particularidade de necessitar de paradas periódicas para recarga da bateria. Ainda, esse sistema tem como característica múltiplos períodos e múltiplas janelas de tempo. Nota-se que o levantamento bibliográfico realizado não apontou nenhuma metodologia diretamente aplicável para solução da aplicação real tratada. Portanto, objetivando provar soluções mais efetivas que as correntemente aplicadas na prática, foi desenvolvido um modelo linear inteiro misto para descrever (e resolver) o problema como um problema de roteamento de veículos com restrições janela de tempo, multi-períodos e paradas periódicas para recarga. Os resultados mostraram que o modelo proposto descreve adequadamente o processo distribuição da empresa, e as soluções obtidas são melhores que as praticadas atualmente. Além disso, verificou-se que o modelo tem um desempenho satisfatório em até 3600 segundos de processamento para instâncias de até 40 clientes, 1 veículo e até 2 postos de recarga. Com vistas ao tratamento de problemas de maior porte, foi desenvolvida uma heurística de programação matemática do tipo Relax-and-Fix para resolução do modelo. Também foi testada a adaptação de um modelo similar presente na literatura, visando analisar se a relaxação de algumas restrições impacta positivamente na qualidade das soluções. Finalmente, é proposto um modelo de localização-distribuição de postos de recarga, de forma a se examinar se a inclusão de novos postos produz melhorias significativas nas soluções atuais. / FAPESP: 14/10330-0
74

Strukturální logiky transformující městské nábřeží v Bratislavě objasnění dynamiky rozhodování o městském rozvoji / Logics transforming the urban waterfront in Bratislava unravelling the decision-making dynamics behind urban development

Machala, Branislav January 2019 (has links)
Extended Abstract This thesis addresses the globalizing urban waterfront in Bratislava. It aims to unravel the key logics driving the decision-making processes behind waterfront re- development in the Slovak capital. I investigate the infiltration of the capitalist logics into a transforming institutional environment unfolding from the post-socialist transition. This is being done through a distinction between the capitalist and the territorial logics of power (Jessop, 1999; Harvey, 2005). Across the globe, waterfront re-development has become the urban response to inner-city decline, and the increasing inter-urban competitiveness in today's neoliberal capitalism. The origins of waterfront transformations are here framed as an urban manifestation of geographically uneven logics of capital put into motion by the crisis of Atlantic Fordism (Smith, 1990; Jessop, 2000). The capital switching into the build-up environment (Harvey, 1978; 2005), is temporarily fixed on urban waterfronts through decisions made on multiple scales (Brenner, 2001). Various types of 'extraverted' strategies such as the Ecosystem approach (Laidley, 2007), a construction of megaprojects & an organisation of mega-events (Orueta & Fainstein 2009), or localization of transnational circulations of stararchitects (Alaily-Mattar et.al. 2018),...
75

從兩岸入世論臺灣承銷商的發展契機 / The opportunity of the underwriting corporation in Taiwan after attending WTO

陳慶洪, Chen, Ching-Hung Unknown Date (has links)
學年度:90 學期:2 校院:國立政治大學 系所:經營管理碩士學程 論文名稱:從兩岸入世論臺灣承銷商的發展契機 學位類別:碩士 研究生:陳慶洪 指導教授:杜化宇 關鍵詞:中國大陸、證券承銷、證券承銷商、發行人、配售方式、詢價圈購、公開申購、競價拍賣、世界貿易組織 中文摘要: 隨著中國大陸經濟的蓬勃發展,股票市場也在這個變動的社會中應運而生。股票市場做為溝通資金供需雙方的重要渠道,是傳統資本主義社會的重要表徵,最早發軔於西歐,臺灣和中國大陸也陸續引進這種商業型態的制度。隨著兩岸分別加入世界貿易組織,股票市場也必須積極地邁向國際化。當歐、美、日等國的投資銀行均已積極地進駐中國大陸,以搶佔其金融市場之際,國內業者受制於兩岸的政治氛圍卻顯得步履蹣跚。然而太晚進入大陸市場,將使國內證券承銷商處於不利的競爭地位。 在WTO的架構下,金融服務業必須受到服務貿易總協定的規範,兩岸都將適用最惠國待遇和多邊諮商原則,所以臺灣對中國大陸以及中國大陸對臺灣的經貿與金融政策都必須作大幅度的調整。臺灣地區的證券承銷商如何掌握此一發展趨勢,以開創華人世紀的新紀元,在在考驗著臺灣政府與業者的智慧。 摘要 回顧八零年代後期,中國大陸在鄧小平的主導下,踏上改革開放的試點工作,低廉的要素成本和政府的政策支持,吸引著外資源源不斷地注入,臺商得文化、地利之便,藉著轉移生產基地以延續產業生命並擴展生產規模。二十餘年來,西進的臺商從勞力密集,逐漸提升到資本密集與技術密集,對國內的經濟發展帶來相當大的衝擊。當臺商在異地逐漸站穩腳步,並於境外獲得資金供給的來源,對國內資本市場的依存度自然降低許多。做為資金供需雙方媒介的國內證券承銷商,遂因而陷入市場萎縮的困境。當兩岸次第加入世貿組織以後,國內承銷商是否有機會跟隨臺商腳步,將市場拓展至中國大陸,以延續生機並再創高峰,的確是一件值得深思的問題。 本研究的第二章、第三章分別介紹中國大陸和臺灣的承銷制度,依序分從 「證券商之分類及其業務範疇」、「承銷時機」、「承銷方式與資格」、「承銷作業程序」和「承銷價格訂定與配售方式」等五個面向加以探討,第四章則從比較制度的觀點,分析兩地承銷制度的異同。為了瞭解WTO入會架構將對兩岸承銷商帶來何等影響,本研究第五章首先介紹世界貿易組織的功能、理念與規範重點,其次則試圖探討兩岸入會後可能面臨的衝擊與因應之道。第六章則以建華金控為例,探討年前國內通過金融業者得以純粹控股公司形式跨業兼營的法令,將對證券承銷業者進軍中國大陸的努力帶來何等影響與可能的限制。 從制度面來看,由於臺海兩岸均係繼受歐美國家的先進體制,只是導入時期先後有別,除因政策性考量產生些許出入外,可說是大同小異。其次,兩岸分別在2001年11月間的卡達會議中獲准加入世界貿易組織,臺灣地區雖以已開發國家身份入世,因入世前長達九年的複邊磋商過程已陸續將相關要求內化,入世後應不致帶來太大的衝擊。而中國大陸係以開發中國家身份爭取入世,因此在國內市場的開放上有較多的調適時間,不過從其最近出台的《外資參股證券公司設立規則》來看,除了對於境外股東的持股比例,依其入世時承諾的進度設定限制外,可說是全面開放證券承銷市場;且該規則亦適用於香港、澳門及臺灣地區的業者。受限於兩岸政權迄今仍處於對立狀態,短期內恐無法假前述規則簽署證券監管合作諒解備忘錄,勢將嚴重斷喪臺灣承銷商西進的發展契機,徒將崛起的商機拱手讓與外資,國內政府誠應審慎考慮此一嚴肅課題,進而積極協助業者排除政治上的障礙,以延續並擴展臺灣業者的生存命脈。 / Academic year: 2001 Session:2 School: National Chengchi University Department: Executive MBA of Finance Title of Thesis: The Opportunity of The Underwriting Corporation in Taiwan After Attending WTO Degree: Master Author: Ching-Hung Chen Advisor: Professor Anthony Tu Keywords: Mainland China, securities underwriting, underwriter, issuer, offering method, book-building, fix-price, auction, WTO Abstract: As the economy of Mainland China is glooming, the stock market arises in the changing society. The stock market is an important channel to link the supply and demand, as well as a symbol of the traditional capitalist society. It has taken a long time for western countries to develop their stock systems. However, similar systems emerged in Taiwan and Mainland China. After Taiwan and Mainland China attending WTO, stock markets must be aggressively facing the globalization. When Europe, the United States, and Japan are going to compete to dominate the Mainland's financial market. Taiwan is moving at a slower pace and facing many restrictions. The late entry of Taiwan's underwriting corporations into the Mainland market will undermine their competitiveness. Under the WTO framework, the basic principles on the financial services sector are governed by the General Agreement on Trade in Services (GATS). Once Taiwan and the Mainland become WTO members, they must both accept all WTO regulations, including those on MFN treatment and multilateral negotiations. In light of these requirements, both Taiwan and the Mainland must make large adjustments in their cross-strait and financial policies toward each other. The underwriting corporations in Taiwan are willing to create a new era. How to grasp the developing tendency is a critical trial to the enterprises and government in Taiwan.
76

Impacts and Detection of Design Smells

Maiga, Abdou 08 1900 (has links)
Les changements sont faits de façon continue dans le code source des logiciels pour prendre en compte les besoins des clients et corriger les fautes. Les changements continus peuvent conduire aux défauts de code et de conception. Les défauts de conception sont des mauvaises solutions à des problèmes récurrents de conception ou d’implémentation, généralement dans le développement orienté objet. Au cours des activités de compréhension et de changement et en raison du temps d’accès au marché, du manque de compréhension, et de leur expérience, les développeurs ne peuvent pas toujours suivre les normes de conception et les techniques de codage comme les patrons de conception. Par conséquent, ils introduisent des défauts de conception dans leurs systèmes. Dans la littérature, plusieurs auteurs ont fait valoir que les défauts de conception rendent les systèmes orientés objet plus difficile à comprendre, plus sujets aux fautes, et plus difficiles à changer que les systèmes sans les défauts de conception. Pourtant, seulement quelques-uns de ces auteurs ont fait une étude empirique sur l’impact des défauts de conception sur la compréhension et aucun d’entre eux n’a étudié l’impact des défauts de conception sur l’effort des développeurs pour corriger les fautes. Dans cette thèse, nous proposons trois principales contributions. La première contribution est une étude empirique pour apporter des preuves de l’impact des défauts de conception sur la compréhension et le changement. Nous concevons et effectuons deux expériences avec 59 sujets, afin d’évaluer l’impact de la composition de deux occurrences de Blob ou deux occurrences de spaghetti code sur la performance des développeurs effectuant des tâches de compréhension et de changement. Nous mesurons la performance des développeurs en utilisant: (1) l’indice de charge de travail de la NASA pour leurs efforts, (2) le temps qu’ils ont passé dans l’accomplissement de leurs tâches, et (3) les pourcentages de bonnes réponses. Les résultats des deux expériences ont montré que deux occurrences de Blob ou de spaghetti code sont un obstacle significatif pour la performance des développeurs lors de tâches de compréhension et de changement. Les résultats obtenus justifient les recherches antérieures sur la spécification et la détection des défauts de conception. Les équipes de développement de logiciels doivent mettre en garde les développeurs contre le nombre élevé d’occurrences de défauts de conception et recommander des refactorisations à chaque étape du processus de développement pour supprimer ces défauts de conception quand c’est possible. Dans la deuxième contribution, nous étudions la relation entre les défauts de conception et les fautes. Nous étudions l’impact de la présence des défauts de conception sur l’effort nécessaire pour corriger les fautes. Nous mesurons l’effort pour corriger les fautes à l’aide de trois indicateurs: (1) la durée de la période de correction, (2) le nombre de champs et méthodes touchés par la correction des fautes et (3) l’entropie des corrections de fautes dans le code-source. Nous menons une étude empirique avec 12 défauts de conception détectés dans 54 versions de quatre systèmes: ArgoUML, Eclipse, Mylyn, et Rhino. Nos résultats ont montré que la durée de la période de correction est plus longue pour les fautes impliquant des classes avec des défauts de conception. En outre, la correction des fautes dans les classes avec des défauts de conception fait changer plus de fichiers, plus les champs et des méthodes. Nous avons également observé que, après la correction d’une faute, le nombre d’occurrences de défauts de conception dans les classes impliquées dans la correction de la faute diminue. Comprendre l’impact des défauts de conception sur l’effort des développeurs pour corriger les fautes est important afin d’aider les équipes de développement pour mieux évaluer et prévoir l’impact de leurs décisions de conception et donc canaliser leurs efforts pour améliorer la qualité de leurs systèmes. Les équipes de développement doivent contrôler et supprimer les défauts de conception de leurs systèmes car ils sont susceptibles d’augmenter les efforts de changement. La troisième contribution concerne la détection des défauts de conception. Pendant les activités de maintenance, il est important de disposer d’un outil capable de détecter les défauts de conception de façon incrémentale et itérative. Ce processus de détection incrémentale et itérative pourrait réduire les coûts, les efforts et les ressources en permettant aux praticiens d’identifier et de prendre en compte les occurrences de défauts de conception comme ils les trouvent lors de la compréhension et des changements. Les chercheurs ont proposé des approches pour détecter les occurrences de défauts de conception, mais ces approches ont actuellement quatre limites: (1) elles nécessitent une connaissance approfondie des défauts de conception, (2) elles ont une précision et un rappel limités, (3) elles ne sont pas itératives et incrémentales et (4) elles ne peuvent pas être appliquées sur des sous-ensembles de systèmes. Pour surmonter ces limitations, nous introduisons SMURF, une nouvelle approche pour détecter les défauts de conception, basé sur une technique d’apprentissage automatique — machines à vecteur de support — et prenant en compte les retours des praticiens. Grâce à une étude empirique portant sur trois systèmes et quatre défauts de conception, nous avons montré que la précision et le rappel de SMURF sont supérieurs à ceux de DETEX et BDTEX lors de la détection des occurrences de défauts de conception. Nous avons également montré que SMURF peut être appliqué à la fois dans les configurations intra-système et inter-système. Enfin, nous avons montré que la précision et le rappel de SMURF sont améliorés quand on prend en compte les retours des praticiens. / Changes are continuously made in the source code to take into account the needs of the customers and fix the faults. Continuous change can lead to antipatterns and code smells, collectively called “design smells” to occur in the source code. Design smells are poor solutions to recurring design or implementation problems, typically in object-oriented development. During comprehension and changes activities and due to the time-to-market, lack of understanding, and the developers’ experience, developers cannot always follow standard designing and coding techniques, i.e., design patterns. Consequently, they introduce design smells in their systems. In the literature, several authors claimed that design smells make object-oriented software systems more difficult to understand, more fault-prone, and harder to change than systems without such design smells. Yet, few of these authors empirically investigate the impact of design smells on software understandability and none of them authors studied the impact of design smells on developers’ effort. In this thesis, we propose three principal contributions. The first contribution is an empirical study to bring evidence of the impact of design smells on comprehension and change. We design and conduct two experiments with 59 subjects, to assess the impact of the composition of two Blob or two Spaghetti Code on the performance of developers performing comprehension and change tasks. We measure developers’ performance using: (1) the NASA task load index for their effort; (2) the time that they spent performing their tasks; and, (3) their percentages of correct answers. The results of the two experiments showed that two occurrences of Blob or Spaghetti Code design smells impedes significantly developers performance during comprehension and change tasks. The obtained results justify a posteriori previous researches on the specification and detection of design smells. Software development teams should warn developers against high number of occurrences of design smells and recommend refactorings at each step of the development to remove them when possible. In the second contribution, we investigate the relation between design smells and faults in classes from the point of view of developers who must fix faults. We study the impact of the presence of design smells on the effort required to fix faults, which we measure using three metrics: (1) the duration of the fixing period; (2) the number of fields and methods impacted by fault-fixes; and, (3) the entropy of the fault-fixes in the source code. We conduct an empirical study with 12 design smells detected in 54 releases of four systems: ArgoUML, Eclipse, Mylyn, and Rhino. Our results showed that the duration of the fixing period is longer for faults involving classes with design smells. Also, fixing faults in classes with design smells impacts more files, more fields, and more methods. We also observed that after a fault is fixed, the number of occurrences of design smells in the classes involved in the fault decreases. Understanding the impact of design smells on development effort is important to help development teams better assess and forecast the impact of their design decisions and therefore lead their effort to improve the quality of their software systems. Development teams should monitor and remove design smells from their software systems because they are likely to increase the change efforts. The third contribution concerns design smells detection. During maintenance and evolution tasks, it is important to have a tool able to detect design smells incrementally and iteratively. This incremental and iterative detection process could reduce costs, effort, and resources by allowing practitioners to identify and take into account occurrences of design smells as they find them during comprehension and change. Researchers have proposed approaches to detect occurrences of design smells but these approaches have currently four limitations: (1) they require extensive knowledge of design smells; (2) they have limited precision and recall; (3) they are not incremental; and (4) they cannot be applied on subsets of systems. To overcome these limitations, we introduce SMURF, a novel approach to detect design smells, based on a machine learning technique—support vector machines—and taking into account practitioners’ feedback. Through an empirical study involving three systems and four design smells, we showed that the accuracy of SMURF is greater than that of DETEX and BDTEX when detecting design smells occurrences. We also showed that SMURF can be applied in both intra-system and inter-system configurations. Finally, we reported that SMURF accuracy improves when using practitioners’ feedback.
77

Impacts and Detection of Design Smells

Maiga, Abdou 08 1900 (has links)
No description available.
78

Simulação Numérica de Escoamento Bifásico em reservatório de Petróleo Heterogêneos e Anisotrópicos utilizando um Método de Volumes Finitos “Verdadeiramente” Multidimensional com Aproximação de Alta Ordem

SOUZA, Márcio Rodrigo de Araújo 22 September 2015 (has links)
Submitted by Fabio Sobreira Campos da Costa (fabio.sobreira@ufpe.br) on 2016-07-01T15:05:14Z No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Souza_Tese_2015_09_22.pdf: 8187999 bytes, checksum: 664629aed28d692dce410fefbfe793dc (MD5) / Made available in DSpace on 2016-07-01T15:05:14Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Souza_Tese_2015_09_22.pdf: 8187999 bytes, checksum: 664629aed28d692dce410fefbfe793dc (MD5) Previous issue date: 2015-09-22 / Anp / Sob certas hipóteses simplificadoras, o modelo matemático que descreve o escoamento de água e óleo em reservatórios de petróleo pode ser representado por um sistema não linear de Equações Diferenciais Parciais composto por uma equação elíptica de pressão (fluxo) e uma equação hiperbólica de saturação (transporte). Devido a complexidades na modelagem de ambientes deposicionais, nos quais são incluídos camadas inclinadas, canais, falhas e poços inclinados, há uma dificuldade de se construir um modelo que represente adequadamente certas características dos reservatórios, especialmente quando malhas estruturadas são usadas (cartesianas ou corner point). Além disso, a modelagem do escoamento multifásico nessas estruturas geológicas incluem descontinuidades na variável e instabilidades no escoamento, associadas à elevadas razões de mobilidade e efeitos de orientação de malha. Isso representa um grande desafio do ponto de vista numérico. No presente trabalho, uma formulação fundamentada no Método de Volumes Finitos é estudada e proposta para discretizar as equações elíptica de pressão e hiperbólica de saturação. Para resolver a equação de pressão três formulações robustas, com aproximação dos fluxos por múltiplos pontos são estudadas. Essas formulações são abeis para lidar com tensores de permeabilidade completos e malhas poligonais arbitrárias, sendo portanto uma generalização de métodos mais tradicionais com aproximação do fluxo por apenas dois pontos. A discretização da equação de saturação é feita com duas abordagens com característica multidimensional. Em uma abordagem mais convencional, os fluxos numéricos são extrapolados diretamente nas superfícies de controle por uma aproximação de alta resolução no espaço (2ª a 4ª ordem) usando uma estratégia do tipo MUSCL. Uma estratégia baseada na Técnica de Mínimos Quadrados é usada para a reconstrução polinomial. Em uma segunda abordagem, uma variação de uma esquema numérico Verdadeiramente Multidimensional é proposto. Esse esquema diminui o efeito de orientação de malha, especialmente para malhas ortogonais, mesmo embora alguma falta de robustez possa ser observada pra malhas excessivamente distorcidas. Nesse tipo de formulação, os fluxos numéricos são calculados de uma forma multidimensional. Consiste em uma combinação convexa de valores de saturação ou fluxo fracionário, seguindo a orientação do escoamento através do domínio computacional. No entanto, a maioria dos esquemas numéricos achados na literatura tem aproximação apenas de primeira ordem no espaço e requer uma solução implícita de sistemas algébricos locais. Adicionalmente, no presente texto, uma forma modificada desses esquemas “Verdadeiramente” Multidimensionais é proposta em um contexto centrado na célula. Nesse caso, os fluxos numéricos multidimensionais são calculados explicitamente usando aproximações de alta ordem no espaço. Para o esquema proposto, a robustez e o caráter multidimensional também leva em conta a distorção da malha por meio de uma ponderação adaptativa. Essa ponderação regula a característica multidimensional da formulação de acordo com a distorção da malha. Claramente, os efeitos de orientação de malha são reduzidos. A supressão de oscilações espúrias, típicas de aproximações de alta ordem, são obtidas usando, pela primeira vez no contexto de simulação de reservatórios, uma estratégia de limitação multidimensional ou Multidimensional Limiting Process (MLP). Essa estratégia garante soluções monótonas e podem ser usadas em qualquer malha poligonal, sendo naturalmente aplicada em aproximações de ordem arbitrária. Por fim, de modo a garantir soluções convergentes, mesmo para problemas tipicamente não convexos, associados ao modelo de Buckley-Leverett, uma estratégia robusta de correção de entropia é empregada. O desempenho dessas formulações é verificado com a solução de problemas relevantes achados na literatura. / Under certain simplifying assumptions, the problem that describes the fluid flow of oil and water in heterogeneous and anisotropic petroleum reservoir can be described by a system of non-linear partial differential equations that comprises an elliptic pressure equation (flow) and a hyperbolic saturation equation (transport). Due to the modeling of complex depositional environments, including inclined laminated layers, channels, fractures, faults and the geometrical modeling of deviated wells, it is difficult to properly build and handle the Reservoir Characterization Process (RCM), particularly by using structured meshes (cartesian or corner point), which is the current standard in petroleum reservoir simulators. Besides, the multiphase flow in such geological structures includes the proper modeling of water saturation shocks and flow instabilities associated to high mobility ratios and Grid Orientation Effects (GOE), posing a great challenge from a numerical point of view. In this work, a Full Finite Volume Formulation is studied and proposed to discretize both, the elliptic pressure and the hyperbolic saturation equations. To solve the pressure equation, we study and use three robust Multipoint Flux Approximation Methods (MPFA) that are able to deal with full permeability tensors and arbitrary polygonal meshes, making it relatively easy to handle complex geological structures, inclined wells and mesh adaptivity in a natural way. To discretize the saturation equation, two different multidimensional approaches are employed. In a more conventional approach, the numerical fluxes are extrapolated directly on the control surfaces for a higher resolution approximation in space (2nd to 4th order) by a MUSCL (Monotone Upstream Centered Scheme for Conservation Laws) procedure. A least squares based strategy is employed for the polynomial reconstruction. In a second approach, a variation of a “Truly” Multidimensional Finite Volume method is proposed. This scheme diminishes GOE, especially for orthogonal grids, even though some lack of robustness can be observed for extremely distorted meshes. In this type of scheme, the numerical flux is computed in each control surface in a multidimensional way, by a convex combination of the saturation or the fractional flow values, following the approximate wave orientation throughout the computational domain. However, the majority of the schemes found in literature is only first order accurate in space and demand the implicit solution of local conservation problems. In the present text, a Modified Truly Multidimensional Finite Volume Method (MTM-FVM) is proposed in a cell centered context. The truly multidimensional numerical fluxes are explicitly computed using higher order accuracy in space. For the proposed scheme, the robustness and the multidimensional character of the aforementioned MTM-FVM explicitly takes into account the angular distortion of the computational mesh by means of an adaptive weight, that tunes the multidimensional character of the formulation according to the grid distortion, clearly diminishing GOE. The suppression of the spurious oscillations, typical from higher order schemes, is achieved by using for the first time in the context of reservoir simulation a Multidimensional Limiting Process (MLP). The MLP strategy formally guarantees monotone solutions and can be used with any polygonal mesh and arbitrary orders of approximation. Finally, in order to guarantee physically meaningful solutions, a robust “entropy fix” strategy is employed. This produces convergent solutions even for the typical non-convex flux functions that are associated to the Buckley-Leverett problem. The performance of the proposed full finite volume formulation is verified by solving some relevant benchmark problems.
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Řízení dynamických systémů v reálném čase / Real Time Dynamic System Control

Veigend, Petr January 2014 (has links)
This thesis deals with the real time dynamic system control and it uses similar computation methods as earlier bachelor thesis. In the beginning of the thesis, some basics from the field of control and regulation are explained. Systems in this thesis are mostly described by differential equations. Because of this, thesis contains a section about solving differential equations. In this section, multiple approaches are covered and compared. The Modern Taylor series method is introduced, which is used by implemented applications. For system simulation, existing software was upgraded and multiple additional utilities were also implemented. The approximation of the transport delay is also mentioned.
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Implementace obecného assembleru / Implementation of General Assembler

Husár, Adam January 2007 (has links)
This thesis describes the design of the universal assembler that represents a part of the Lissom project. You will be provided with the description of the assembler architectures and their usual tasks. Special attention is paid to GNU assembler. Designed assembler consists of the fixed and the generated part. The generated part is created automatically from the description of instruction set, that is defined using architecture and instructions set description language ISAC. Using this approach, it is possible to change assembler target architecture automatically. The second part of thesis describes the Parserlib2 library implementation that is a part of the Lissom project and provides the information about the target instruction set for an assembler generator.

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