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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.
1

The behaviour of thin walled pipes in trenches

Bueno, Benedito de Souza January 1987 (has links)
No description available.
2

Evaluation des courbes de vulnerabilité sismique d'un réseau de conduites enterrées / Assessment of seismic vulnerability curves for burried pipelines

Halfaya, Fatma Zohra 16 December 2013 (has links)
Les travaux effectués dans le cadre de cette thèse portent sur l’analyse de la vulnérabilité sismique des canalisations enterrés d’un réseau d’alimentation en eau potable (AEP). Ceci afin de disposer d’outils fiables permettant le diagnostique et le ciblage des interventions à même de réduire le risque de perte dans ce réseau en cas de tremblement de terre. Un exemple d’application des concepts développés dans cette étude porte sur la ville de Blida qui possède une infrastructure économique importante et dont le réseau constitue un échantillon représentatif des réseaux d’AEP des villes Algériennes. Ce réseau a été mis sous Système d’Information Géographique (SIG) afin de permettre une lecture aisée des différents résultats. Deux approches ont été utilisées pour appréhender ce problème de vulnérabilité, une approche statistique et une approche numérique. L’approche statistique utilise le retour d’expérience sismique comme base et a permis de d’identifier les paramètres ayant une influence sur le comportement sismique d’un tronçon de canalisation. Des coefficients de pondération ont été déterminés à partir d’analyse de données post sismique ce qui a conduit à la définition d’un indice de vulnérabilité. Ce dernier permet une classification des canalisations enterrées en fonction de leur vulnérabilité. Des courbes de vulnérabilité sont également proposées. L’approche numérique utilise le concept de macroéléments pour modéliser le comportement d’une canalisation enterrée sous sollicitation sismique en considérant l’interaction sol-conduite. Les champs proches et lointains sont considérés à travers un macroélément, de même que le comportement du joint entre deux tronçons. Une stratégie de calcul a été élaborée et testée sur un exemple de conduite. Les résultats obtenus décrivent le comportement réel des tuyauteries lors d’un tremblement de terre. Ils permettent d’affiner les coefficients de l’approche statistique et les calculs pourront être utilisés pour construire les courbes de vulnérabilité / Within this work, seismic vulnerability of buried pipelines is investigated. This is to provide reliable tools allowing the diagnosis and the targeting of interventions that can reduce the risk of loss in the water network in case of an earthquake. A case study focused on the city of Blida is analyzed in order to apply the developed concepts herein. Blida has a large economic infrastructure and its water network is a representative sample of the water supply systems of Algerian cities. This network was put under a Geographic Information System (GIS) to allow easy interpretation of the different results. Two approaches were used to study this vulnerability problem, a statistical method and a numerical method. Thestatistical approach uses the seismic feedback experiences as a basis to identify the parameters that have an influence on the seismic behavior of a pipe. Weighting factors are determined too, allowing the definition of a vulnerability index. This one enables the classification of buried pipelines according their vulnerability. Vulnerability curves are also proposed. The numerical approach uses the concept of macro element to model the behavior of a buried pipeline under seismic solicitation taking into account the soil structure interaction. Far field and near field are considered through the use of a maco element, another macoelement is developed for the joint between two pipes. A computational strategy is developed and tested on a sample. The results describe the behavior of pipes during an earthquake. They allow a refinement of the statistical approach coefficients and the methodology can be used to build vulnerability curves.
3

Numeric Modelling of Water Hammer Effects in Penstocks

Bernard, Dominic 08 May 2013 (has links)
Water hammer represents a complex hydraulic phenomenon with significant consequences on the proper functioning and safety of operation for pipe and conduit systems. The complexity and intricate physics of water hammer translated into significant difficulties associated firstly, with finding a proper solution for understanding the mechanism of its occurrence and, secondly, relating to proposing technically and economically viable design methods and devices that would help reduce and mitigate water hammer effects. In this context, the present thesis deals with the numerical modeling of the transient behaviour of water pipe segments. Following an extensive literature review of the state-of-the-art on the water hammer mechanisms and past work on experimental, analytical and numerical analysis of this phenomenon, a three dimensional numerical model of the water hammer in a pipe which considers the fluid-structure interaction (FSI) is developed using a Finite Element Method – Finite Volume Method (FEM-FVM) technique. Structural and fluid computational results based on rapid and slow gate closure scenarios are compared with existing closed-form solutions of the water hammer. A parametric study is also performed on a simply supported pipe segment to determine the influence of various design parameter. A systematic sensitivity analysis was conducted and a ranking mechanism was established for the importance of each parameter on the fluid fields and structural response. A first comparative analysis is conducted on horizontally and vertically bent elevated pipe segments to quantify the influence of the bend angle on the results. A second comparative analysis is performed on a horizontally bent segment buried in soil to determine the influence of the pipe interaction with the soil on the response. It is observed that the thickness, span, initial velocity and bend angle had a significant impact on the pressure and structural response. The presence of soil was observed to have a significant benefit in decreasing the von-Mises stresses.
4

Numeric Modelling of Water Hammer Effects in Penstocks

Bernard, Dominic January 2013 (has links)
Water hammer represents a complex hydraulic phenomenon with significant consequences on the proper functioning and safety of operation for pipe and conduit systems. The complexity and intricate physics of water hammer translated into significant difficulties associated firstly, with finding a proper solution for understanding the mechanism of its occurrence and, secondly, relating to proposing technically and economically viable design methods and devices that would help reduce and mitigate water hammer effects. In this context, the present thesis deals with the numerical modeling of the transient behaviour of water pipe segments. Following an extensive literature review of the state-of-the-art on the water hammer mechanisms and past work on experimental, analytical and numerical analysis of this phenomenon, a three dimensional numerical model of the water hammer in a pipe which considers the fluid-structure interaction (FSI) is developed using a Finite Element Method – Finite Volume Method (FEM-FVM) technique. Structural and fluid computational results based on rapid and slow gate closure scenarios are compared with existing closed-form solutions of the water hammer. A parametric study is also performed on a simply supported pipe segment to determine the influence of various design parameter. A systematic sensitivity analysis was conducted and a ranking mechanism was established for the importance of each parameter on the fluid fields and structural response. A first comparative analysis is conducted on horizontally and vertically bent elevated pipe segments to quantify the influence of the bend angle on the results. A second comparative analysis is performed on a horizontally bent segment buried in soil to determine the influence of the pipe interaction with the soil on the response. It is observed that the thickness, span, initial velocity and bend angle had a significant impact on the pressure and structural response. The presence of soil was observed to have a significant benefit in decreasing the von-Mises stresses.
5

<<經法>>等佚書之思想研究

林素珍, LIN, SU-ZHEN Unknown Date (has links)
中國自古即有以書籍做為陪葬品的風俗.這些殉葬的書籍若被後世挖掘出來,除了可 據此對傳世古籍進行校對、勘誤外,更有助於學術思想的研究.由此,民國六十二年 湖南長沙馬王堆三號漢墓出土的《經法》、《十六經》、《稱》、《道原》等四篇古 佚書,自然具有珍貴的學術價值. 檢諸四篇佚書的思想,融合了儒、道、墨、法、名、陰陽等各家學說為一體.它們的 出現,不但對先秦至漢代學術的轉關提供了重要線索,更是研究漢初黃老治術的主要 參考文獻,因此對其思想作一整體性的研究,自有其必要性.然而,學界前輩或因研 究重點不同,而少有這方面的探討文字,故初作嘗試,期能對學者鮮為從事的範疇略 作補白. 本文之撰寫,以出土之文獻資料為主,並援引正史載記、參考諸子典籍、廣納學者各 方面的研究結果,從事論證、分析、歸納、比較等方式之研究.此外,亦採取學術流 變及歷史考證的觀點行文,力求說理立論之合乎邏輯,以存說備考,就教學界. 至於其章次內容,除第一章與第十章之緒論、結論之外,則分述如下: 第二章《經法》等佚書之簡介 第三章《經法》等佚書之時代背景 第四章《經法》等佚書之思想淵源 第五章《經法》等佚書之思想本質 第六章《經法》等佚書之思想體系 第七章《經法》等佚書之黃老學 第八章《經法》等佚書之影響 第九章《經法》等佚書之亡佚原因

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