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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.
21

Wave-Associated Seabed Behaviour near Submarine Buried Pipelines

Shabani, Behnam January 2008 (has links)
Master of Engineering (Research) / Soil surrounding a submarine buried pipeline consolidates as ocean waves propagate over the seabed surface. Conventional models for the analysis of soil behaviour near the pipeline assume a two-dimensional interaction problem between waves, the seabed soil, and the structure. In other words, it is often considered that water waves travel normal to the orientation of pipeline. However, the real ocean environment is three-dimensional and waves approach the structure from various directions. It is therefore the key objective of the present research to study the seabed behaviour in the vicinity of marine pipelines from a three-dimensional point of view. A three-dimensional numerical model is developed based on the Finite Element Method to analyse the so-called momentary behaviour of soil under the wave loading. In this model, the pipeline is assumed to be rigid and anchored within a rigid impervious trench. A non-slip condition is considered to exist between the pipe and the surrounding soil. Quasi-static soil consolidation equations are then solved with the aid of the proposed FE model. In this analysis, the seabed behaviour is assumed to be linear elastic with the soil strains remaining small. The influence of wave obliquity on seabed responses, i.e. the pore pressure and soil stresses, are then studied. It is revealed that three-dimensional characteristics systematically affect the distribution of soil response around the circumference of the underwater pipeline. Numerical results suggest that the effect of wave obliquity on soil responses can be explained through the following two mechanisms: (i) geometry-based three-dimensional influences, and (ii) the formation of inversion nodes. Further, a parametric study is carried out to investigate the influence of soil, wave and pipeline properties on wave-associated pore pressure as well as principal effective and shear stresses within the porous bed, with the aid of proposed three-dimensional model. There is strong evidence in the literature that the failure of marine pipelines often stems from the instability of seabed soil close to this structure, rather than from construction deficiencies. The wave-induced seabed instability is either associated with the soil shear failure or the seabed liquefaction. Therefore, the developed three-dimensional FE model is used in this thesis to further investigate the instability of seabed soil in the presence of a pipeline. The widely-accepted criterion, which links the soil liquefaction to the wave-induced excess pressure is used herein to justify the seabed liquefaction. It should be pointed out that although the present analysis is only concerned with the momentary liquefaction of seabed soil, this study forms the basis for the three-dimensional analysis of liquefaction due to the residual mechanisms. The latter can be an important subject for future investigations. At the same time, a new concept is developed in this thesis to apply the dynamic component of soil stress angle to address the phenomenon of wave-associated soil shear failure. At this point, the influence of three-dimensionality on the potentials for seabed liquefaction and shear failure around the pipeline is investigated. Numerical simulations reveal that the wave obliquity may not notably affect the risk of liquefaction near the underwater pipeline. But, it significantly influences the potential for soil shear failure. Finally, the thesis proceeds to a parametric study on effects of wave, soil and pipeline characteristics on excess pore pressure and stress angle in the vicinity of the structure.
22

Controlled Source Radiomagnetotelluric (CSRMT) Applications in Environmental and Resource Exploration

Ismail, Nazli January 2009 (has links)
An integrated use of radio magnetotelluric (RMT) and controlled source tensor magnetotelluric (CSTMT) measurements, the so-called CSRMT method, has been employed in environmental and resource exploration studies. A number of case histories, including a groundwater investigation in glacial deposits, a study of fracture zones for geotechnical purposes and a mining exploration study of a copper deposit, are presented in this thesis in order to illustrate the usefulness and capability of the CSRMT method. The resolutions of the estimated models using various types of data are studied. Magnetotelluric transfer functions are used to analyze the dimensionality, the near surface resistivity distortions and the near field effects in the case of CSTMT data analysis. The near field effects in CSTMT data have also been identified by performing 2½D forward modelling. Data analysis, dimensionality tests and forward modelling show that at the lowest frequencies used the CSTMT transfer functions are generally distorted by source effects, except when the source-receiver distances are sufficient large compared with the penetration depth. Regarding CSTMT transfer functions, apparent resistivities are generally less distorted than phases. TM mode transfer functions are more affected by the sources than TE mode, while tipper vectors generally contain source signatures at all frequencies. Based on the analysis of dimensionality and source effects 2D inverse modelling of CSTMT and RMT data, as well as their combination, have been performed under the plane wave assumption. The RMT method proved to be a powerful tool for imaging the upper 50 m near-surface, but their penetration depth reduces as a conductive layer structures cover the targets at depth. The penetration depth can be increased by including the CSTMT data in the modelling if the measurements are in the far field range. The resolution of the deeper parts of the models may be improved by performing a joint inversion of TE and TM modes, if the strike direction is well-defined. Alternatively, inversion of determinant data can be performed, since the determinant data are less affected by 3D structures and source effects. However the resolution of the determinant models is somewhat degraded compared to the models inverted from combined TE and TM modes.
23

Wave-Associated Seabed Behaviour near Submarine Buried Pipelines

Shabani, Behnam January 2008 (has links)
Master of Engineering (Research) / Soil surrounding a submarine buried pipeline consolidates as ocean waves propagate over the seabed surface. Conventional models for the analysis of soil behaviour near the pipeline assume a two-dimensional interaction problem between waves, the seabed soil, and the structure. In other words, it is often considered that water waves travel normal to the orientation of pipeline. However, the real ocean environment is three-dimensional and waves approach the structure from various directions. It is therefore the key objective of the present research to study the seabed behaviour in the vicinity of marine pipelines from a three-dimensional point of view. A three-dimensional numerical model is developed based on the Finite Element Method to analyse the so-called momentary behaviour of soil under the wave loading. In this model, the pipeline is assumed to be rigid and anchored within a rigid impervious trench. A non-slip condition is considered to exist between the pipe and the surrounding soil. Quasi-static soil consolidation equations are then solved with the aid of the proposed FE model. In this analysis, the seabed behaviour is assumed to be linear elastic with the soil strains remaining small. The influence of wave obliquity on seabed responses, i.e. the pore pressure and soil stresses, are then studied. It is revealed that three-dimensional characteristics systematically affect the distribution of soil response around the circumference of the underwater pipeline. Numerical results suggest that the effect of wave obliquity on soil responses can be explained through the following two mechanisms: (i) geometry-based three-dimensional influences, and (ii) the formation of inversion nodes. Further, a parametric study is carried out to investigate the influence of soil, wave and pipeline properties on wave-associated pore pressure as well as principal effective and shear stresses within the porous bed, with the aid of proposed three-dimensional model. There is strong evidence in the literature that the failure of marine pipelines often stems from the instability of seabed soil close to this structure, rather than from construction deficiencies. The wave-induced seabed instability is either associated with the soil shear failure or the seabed liquefaction. Therefore, the developed three-dimensional FE model is used in this thesis to further investigate the instability of seabed soil in the presence of a pipeline. The widely-accepted criterion, which links the soil liquefaction to the wave-induced excess pressure is used herein to justify the seabed liquefaction. It should be pointed out that although the present analysis is only concerned with the momentary liquefaction of seabed soil, this study forms the basis for the three-dimensional analysis of liquefaction due to the residual mechanisms. The latter can be an important subject for future investigations. At the same time, a new concept is developed in this thesis to apply the dynamic component of soil stress angle to address the phenomenon of wave-associated soil shear failure. At this point, the influence of three-dimensionality on the potentials for seabed liquefaction and shear failure around the pipeline is investigated. Numerical simulations reveal that the wave obliquity may not notably affect the risk of liquefaction near the underwater pipeline. But, it significantly influences the potential for soil shear failure. Finally, the thesis proceeds to a parametric study on effects of wave, soil and pipeline characteristics on excess pore pressure and stress angle in the vicinity of the structure.
24

Análise da deslocabilidade lateral de edifícios de múltiplos andares com modelos tridimensionais de barra / Analysis of lateral displaceability of multi-storey building with bar tridimensional models

Avilla, Marcella Caon 31 August 2016 (has links)
Submitted by Aelson Maciera (aelsoncm@terra.com.br) on 2017-03-29T18:21:36Z No. of bitstreams: 1 DissMCAad.pdf: 6301246 bytes, checksum: 1a4544ba506998d2e95d6d0e3106cbc2 (MD5) / Approved for entry into archive by Ronildo Prado (ronisp@ufscar.br) on 2017-04-03T20:08:32Z (GMT) No. of bitstreams: 1 DissMCAad.pdf: 6301246 bytes, checksum: 1a4544ba506998d2e95d6d0e3106cbc2 (MD5) / Approved for entry into archive by Ronildo Prado (ronisp@ufscar.br) on 2017-04-03T20:08:41Z (GMT) No. of bitstreams: 1 DissMCAad.pdf: 6301246 bytes, checksum: 1a4544ba506998d2e95d6d0e3106cbc2 (MD5) / Made available in DSpace on 2017-04-03T20:13:28Z (GMT). No. of bitstreams: 1 DissMCAad.pdf: 6301246 bytes, checksum: 1a4544ba506998d2e95d6d0e3106cbc2 (MD5) Previous issue date: 2016-08-31 / Não recebi financiamento / The structural modeling of mult-storey buildings using the simplified model in which the slabs is calculated in isolation and their efforts transferred to a three-dimensional frames is now overcome by the state of the art computational analysis. Currently even with structures formed by bar elements (three-dimensional frames) it is possible to make the analysis considering the effect monolithic of concrete structures or operating as a whole. For certain cases, it is essential to consider all the structural elements participating in the bracing to the structure is presented stable in the horizontal actions combined with vertical actions, such as the flat slabs systems.Through of analysis examples of structures of buildings with multiple floors in reinforced concrete are presented advantages in performing three-dimensional modeling, comparing the results obtained with the simplified models. It shows the importance of considering the slab stiffness in flat slabs systems and how the distribution of efforts to change the three-dimensional model. Analyses are done using commercial software tool allowing verify quantitative variation of structural materials. Finally an analysis is made of the examples made showing the main differences in the new models. / A modelagem estrutural de edifícios de múltiplos andares usando o modelo simplificado no qual o pavimento é calculado de forma isolada e seus esforços transferidos para um pórtico tridimensional hoje está superada pelo estado da arte da análise computacional. Atualmente mesmo com estruturas constituídas por elementos de barras (pórticos tridimensionais) já é possível fazer a análise considerando o efeito monolítico das estruturas de concreto, ou seja, funcionando com um todo. Para determinados casos, é fundamental a consideração de todos os elementos estruturais participando do contraventamento para que a estrutura se apresente estável frente às ações horizontais combinadas com as ações verticais, como, por exemplo, os sistemas de lajes lisas. Por meio das análises de alguns exemplos de estruturas de edifícios de múltiplos pavimentos de concreto armado são apresentadas as vantagens em se realizar a modelagem tridimensional, comparando-se os resultados obtidos com os dos modelos simplificados. Mostra-se a importância da consideração da rigidez da laje em sistemas de lajes lisas e como a distribuição de esforços se altera no modelo tridimensional. As análises são feitas através de ferramenta computacional comercial permitindo assim verificar a variação de quantitativo de materiais estruturais. Por fim é feita uma análise dos exemplos realizados mostrando as principais diferenças encontradas nos novos modelos.
25

Desenvolvimento de modelo numerico tridimensional e eliptico para o estudo de escoamentos no interior de dutos cilindricos / Development of three-dimensional and elliptical numerical model for the study of fluid flow in cylindrical ducts

Lopes, Gabriela Cantarelli 27 June 2008 (has links)
Orientador: Jose Roberto Nunhez / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Quimica / Made available in DSpace on 2018-08-11T08:15:27Z (GMT). No. of bitstreams: 1 Lopes_GabrielaCantarelli_M.pdf: 1710566 bytes, checksum: efab0c6308734536b15c2ef91d4d8337 (MD5) Previous issue date: 2008 / Resumo: Processos que envolvem escoamentos de fluidos no interior de dutos estão presentes em muitas aplicações industriais. Na indústria petroquímica um desses processos que vem se tornando cada vez mais importante é o craqueamento catalítico de frações pesadas do petróleo, já que as converte em frações leves e mais nobres. Por causa da crescente demanda mundial por gasolina e GLP e à sua alta rentabilidade para uma refinaria de petróleo, unidades de craqueamento catalítico em leito fluidizado (FCC) estão presentes em todo o mundo. Testes experimentais costumam ser usados no estudo dos fenômenos envolvidos nesse processo. Porém esse tipo de análise possui alto custo, que pode ser reduzido com o uso de simulações computacionais em seu estudo inicial. Assim, o objetivo deste trabalho foi desenvolver um modelo tridimensional e elíptico, em linguagem Fortran, capaz de fornecer dados para a análise preliminar de escoamentos no interior de reatores de FCC. Na modelagem desses problemas são usadas equações diferenciais parciais, e essas não possuem solução analítica conhecida, sendo necessário o emprego de métodos numéricos para esse fim. Neste trabalho foi usado o Método dos Volumes Finitos, que tem a função de substituir as equações diferenciais parciais por equações algébricas aplicadas a pequenos volumes de controle finitos pertencentes ao domínio. Uma das maiores dificuldades encontradas no tratamento numérico de escoamentos incompressíveis é a determinação de um campo de pressão que satisfaça a Equação da Continuidade. Esse problema foi resolvido fazendo-se uso da abordagem acoplp.da de solução. Para análise do modelo foram obtidos perfis numéricos de velocidade e pressão para fluidos escoando em regimes laminar e turbulento, que foram validados usando-se os dados obtidos com a solução analítica das equações, por correlações (semi-) empíricas ou por dados experimentais, conforme cada um dos casos. Notou-se que o modelo representa muito bem casos laminares, e gue 11.oS casos turbulentos foi necessário um maior refino da malha próximo a parede do tubo. Também foram feitas simulações para que se pudessem observar as características tridimensionais, elípticas e transientes da modelagem do escoamento. De maneira geral o modelo se mostrou bastante rápido, convergindo em poucas iterações. Palavras-Chave: Fluidodinâmica computacional; dutos cilíndricos; modelo tridimensional e elíptico; método dos Volumes Finitos; solução acoplada; turbulência / Abstract: Processes involving fluid flow in tubes are present in many industrial applications. In petrochemical industry one of these processes that are becoming more and more important is the fluid catalytic cracking of heavy petroleum fractions. This fact is due to the process capacity to convert heavy fractions in light and valuable ones. Because of the increasingly worldwide demand for gasoline and LPG and its high yield for a petroleum refinery, fluid catalytic cracking (FCC) units are present in the whole world. Experimental tests are used in the study of the phenomena involved in this processo However this kind of analysis has high cost which can be reduced by using computational simulations in its initial study. Thus, the aim of this work was the development of a three-dimensional and elliptical mo dei in Fortran language in order to provide data for fluid flow preliminary analysis in FCC reactors. Partial differential equations were used in the modeling of these problems. These equations do not have known analytical solution, being necessary therefore the use of numerical methods. In this work the Finite Volume Method were applied with this purpose. This method has as a role to substitute the partial differential equations of the mo dei for algebric equations applied to small finite control volumes of the domain. One of the biggest difficulties found in the numerical treatment of incompressible fluid flows is the determination of apressure field that satisfies the Continuity Equation. This problem was solved using the coupled solution approach. For model analysis, numerical velocity and pressure proJ:iles for laminar and turbulent flows were obtained, that had been validated using the data obtained through the analytical solution of the equations, by empirical correlations or by experimental data, according to each one of the cases. The model represented well laminar cases, and in the turbulent ones the mesh had to be more refined near the tube wall. Other simulations were performed, in aQalyzing the three-dimensional, elliptical and transient model characteristics. In general, the mo dei was very fast, converging in a few interations. Keywords: Computational fluid dyn~mic; cylindrical ducts; three-dimensional and elliptical model; Finite Volume Method; coupled solution; turbulence / Mestrado / Desenvolvimento de Processos Químicos / Mestre em Engenharia Química
26

Možnosti veřejné politiky ve zvyšování politické informovanosti dospělých občanů v České republice / Public Policy Options in Increasing Political Sophistication of Adult Citizens in the Czech Republic

Černá, Lucie January 2015 (has links)
This thesis presents the theme of low political awareness of adult citizens in the Czech Republic from the perspective of public policy. Low level of political awareness is conceived as a major reason that voters are not able to vote according to their real interests. The focus is on whether the problem is a topic that public policy should pursue and whether it is possible to find a public policy tools to deal with it. It is mainly based on the three-dimensional model of political sophistication, Evert Vedung's concept of public policy instruments, the concept of the correct voting and ideas of participatory democracy. Despite the fact that the given issue bears the hallmarks of an ideal problem for public policy and we can find some tools that could improve the current situation, there are broader factors that hinder their operations. These include the impact of previous undemocratic regime or the behavior of politicians. Such barriers are closely related to the way of human thinking and can be removed only with difficulty.
27

Utvecklingsmöjligheter inom ledarskapet : En kvalitativ studie som undersöker en ledare genom tre-dimensionsmodellen och en 360-graders utvärdering för att skapa förutsättningar för utveckling / Development opportunities within the leadership role : A qualitative study that examines a leader through the three-dimensional model and a 360-degree appraisal feedback process in order to create conditions for development

Emanuelsson, Jesper, Lidén, Theodor, Pontén, Karl January 2023 (has links)
Bakgrund Bakgrunden till arbetet grundar sig i att ledarskap är ett komplext ämne som kan definieras på flera olika sätt. I det här arbetet bryter vi ner definitionen av ledarskap och utgår från tre ledarskapsstilar. Ledarskap är ett relevant och viktigt fenomen att studera då det återfinns överallt i samhället och kan skapa en känsla av sammanhang. Det finns också risker med ledarskap som kan leda till minskad arbetstillfredsställelse, fel beslut eller att organisationen tappar konkurrensfördelar. Syfte I denna studie undersöks ledarskapet genom tre-dimensionsmodellen som omfattas av relationsorienterat, uppgiftsorienterat samt förändrings- och utvecklingsorienterat ledarskap. Syftet med studien är att undersöka samt analysera ledarskapet genom både tre-dimensionsmodellen och en 360 graders utvärdering för att därigenom belysa aspekter av ledarskapet samt skapa förutsättningar till utveckling inom ledarskapet. Detta genom attkombinera tre-dimensionsmodellen med en 360 graders utvärdering som innebär att den aktuella ledaren får återkoppling både horisontellt och vertikalt. Metod Arbetet bygger på kvalitativ metod i form av semi-strukturerade intervjuer. Det genomfördes totalt nio intervjuer. De nio intervjupersoner som deltog i studien var den aktuella ledare, ledarens chef, två kollegor och fem medarbetare. Slutsats Studien undersöker en ledare inom en organisation i syfte att belysa delar som appliceras inom ledarskapet. Men även för att fånga upp och lyfta fram utvecklingsmöjligheter för organisationen och den aktuella ledaren. Studien kan användas som vägledning för att öka kompetensen kring ledarskap. Studien visar att en 360 graders utvärdering kan skapa förutsättningar för utveckling inom ledarskapet. Genom en 360 graders utvärdering etablerasen bild av ledaren från flera perspektiv vilket bidar till att skapa en bild och lägga ett pussel som visar ledarens egenskaper utifrån fler perspektiv i syfte att lyfta fram utvecklingsmöjligheter hos den aktuella ledaren. / Background Leadership is a complex subject that requires several definitions. In this study, we will break down the definition of leadership into three different styles. The subject of leadership is a relevant and important topic to study due to its prevalence in society, and its ability to create a context. There are also risks surrounding the leadership role which may lead to a decreased satisfaction at work, making wrong decisions, or loosing competitive advantages. Purpose In this study, the subject of leadership is examined through the three-dimensional model, which consists of relationship-oriented, task-oriented, and change- and development-oriented leadership. The purpose of this study is to examine and analyze leadership through the three-dimensional model and a 360-degree appraisal feedback process and highlight the leadership aspect, in order to create conditions for leadership development. By combining the two methods, the leader will receive feedback both horizontally and vertically. Method This study is based on a qualitative method in the shape of semi-structured interviews. A total of nine interviews were conducted. The people who were interviewed were: a leader, the boss of a leader, two colleagues of a leader as well as five employees of a leader.  Conclusion This study examines the role of a leader within an organization with the aim of highlighting leadership applications and to highlight opportunities for development, both for the organization and the leader. This study can be used as a guide in order to increase knowledge around the subject of leadership. The study shows that the application of a 360-degree appraisal feedback process can create conditions for development within leadership. By using this survey, we will look at the role of the leader from several perspectives in order to highlight development opportunities within the leadership.
28

Experimental and Analytical Collapse Evaluation of an Existing Building

Akah, Ebiji Anthony 15 October 2015 (has links)
No description available.
29

Micromoulding: extreme process monitoring and in-line product assessment.

Whiteside, Benjamin R., Howell, Ken B., Martyn, Michael T., Spares, Robert 08 June 2009 (has links)
No / Advances in micromoulding technology are now allowing mass production of complex, three-dimensional functional products having sub-milligram masses and carefully tailored surface finishes. In order to create a viable manufacturing process for these components, accurate process monitoring and product evaluation are essential in order to highlight process problems and production of substandard parts. The present study describes work implementing a suite of sensors on a commercial micromoulding machine for detailed process interrogation. Evaluation of demoulded products is performed with a single camera based system combined with custom software to allow for three-dimensional characterisation of products during the process.
30

Разработка методических рекомендаций для проверки цифровой информационной модели в ГАУ СО «Управление государственной экспертизы» : магистерская диссертация / Development of methodological recommendations for checking the digital information model in the State Autonomous Institution SO “Office of State Expertise”

Литуева, Ю. Д., Litueva, Yu. D. January 2024 (has links)
Цель работы − разработка методических рекомендаций по проведению проверки цифровой информационной модели раздела АР, КР и ПБ формата ifc для ГАУ СО «Управление государственной экспертизы». Для достижения поставленной цели были поставлены следующие задачи: построить модель и наполнить ее требуемой информацией, используя возможности ПО Revit; выделить основные принципы подготовки ЦИМ к экспертизе; проверить информацию из модели в формате IFC с помощью ПО Tangl Control. Сформировать проверки валидации и верификации; сформировать методические рекомендации, описывающие проведение проверки ЦИМ АР и КР в ПО Tangl Control экспертизой. / The purpose of the work is to develop methodological recommendations for checking the digital information model of the section AR, KR and PB in the ifc format for the State Autonomous Institution SO “Office of State Expertise”. To achieve this goal, the following tasks were set: build a model and fill it with the required information using the capabilities of Revit software; highlight the basic principles of preparing CIM for examination; check the information from the model in IFC format using Tangl Control software. Create validation and verification checks; create methodological recommendations describing the verification of CIM AR and KR in Tangl Control software by expert examination.

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