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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

Effects Of Different Bed Roughnesses On The Characteristics Of Hydraulic Jumps

Velioglu, Deniz 01 February 2012 (has links) (PDF)
In practice, baffle blocks and sills are commonly being used to stabilize the location of a hydraulic jump and shorten the length of a stilling basin. On the other hand, gravels, corrugations and rectangular prismatic roughnesses which cover the entire length of the basin or placed in a staggered manner may be an alternative. The objective of this study is to determine the effects of these roughness elements on the characteristics of hydraulic jumps such as conjugate depth, jump length and energy dissipation using experimental data collected from the previous studies. The investigations show that the roughness elements have positive effects on the characteristics of hydraulic jumps. The tailwater depth reduction compared to classical jump is 2-10%. The length of the jump is reduced about by 30-50% by prismatic roughness elements, 40% by corrugations, and 30% by gravels. The roughness elements induce 3-15% more energy dissipation than that of classical jump. Therefore, these types of bed roughness elements should be considered as an effective alternative of accessory devices such as baffle blocks and sills.
12

The Effect Of Prismatic Roughness Elemnts On Hydraulic Jump

Evcimen, Taylan Ulas 01 January 2005 (has links) (PDF)
The objective of this study is to determine the effect of different roughness types and arrangements on hydraulic jump characteristics in a rectangular channel. Three different types of roughness were used along experiments. All of them had rectangular prism shapes and that were placed normal to the flow direction. To avoid cavitation, height of roughness elements were arranged according to level of the channel inlet, so that the crests of roughness elements would not be protruding into the flow. The effects of roughness type and arrangement on hydraulic jump properties, i.e. energy dissipation, length of the jump and tail water depth were investigated. These properties were compared with the available data in literature and with the properties of hydraulic jump occurred on smooth bed.
13

Estudo de silos metálicos prismáticos para fábricas de ração / Study steel prismatic silos for ration industry

José Wallace Barbosa do Nascimento 14 August 1996 (has links)
Esta pesquisa foi desenvolvida com o objetivo de fornecer subsídios técnicos para projetos de silos prismáticos metálicos para uso industrial, mais especificamente para fábricas de ração, como também contribuir para o desenvolvimento da futura norma brasileira específica para projeto de ações e fluxo em silos. Apresenta-se uma análise da evolução técnica das fábricas de ração no mundo até os dias de hoje com a concepção atual, atendendo às exigências de mercado que, a cada dia, torna-se mais competitivo e necessita do controle de qualidade total para preencher os pré-requisitos das normas nacionais e internacionais, já que o país está abrindo o mercado ao capital externo. Determinou-se as propriedades físicas de dois tipos de ração e de seus ingredientes, que são utilizados na maioria das rações fabricadas no país. Estas são as primeiras propriedades determinadas no país, com a máquina TSG70-140 conhecida em nível mundial como \"Jenike Shear Cell\' e recomendada pela maioria das normas de ações em silos existentes no mundo, com a finalidade da adoção dos parâmetros necessários para o cálculo das ações e fluxo de produtos armazenados. Foram estudados os painéis de construção de silos prismáticos para fábrica de ração com conformação ziguezague na horizontal e inclinação de 20° com o plano vertical, para aumentar a inércia das paredes e não acumular ração, que provocaria deterioração e/ou infestação de fungos e bactérias os quais contaminariam as rações, provocando danos econômicos aos fabricantes e aos criadores de animais. Foram feitos ensaios para determinar a rigidez e a resistência dos painéis conformados em ziguezague, em escala natural, que formaram as paredes dos silos prismáticos para a construção modular. Os resultados experimentais foram comparados com os obtidos com as teorias simplificadas propostas para o cálculo estrutural de silos e com o software estrutural LUSAS, que utiliza o métodos dos elementos finitos. A comparação dos resultados teóricos com os obtidos experimentalmente mostram que a teoria de TROITSKY (1988) apresenta boa correlação, portanto é adequada para o dimensionamento dos painéis. / This research was developed purposing to generate technical hints for the design of steel prismatic silos for industrial use, especially in the powder industry, as well as to contribute for the set up latter on of a Brazilian standard specifically for the design of actions and flow in silos. The world powder industry technological evolution up to now was evaluated, trying to take care of the trade demand, that always becomes more competitive, and thus requiring a total quality control to match the national and international standards, mostly because the Brazilian trade getting so much attractive to the foreign capital. It was determined the physical properties of the ingredients of two kinds of powder, which are used in most of the powder made in Brazil. These are the first properties evaluated in Brazil with the TSG70-140 machine, that is known over the world as \"Jenike Shear Cell\", and is recommend by most of the silo action standard existing in the word, with the purpose of adopting the necessary parameters to calculation of action and flow of materials storage. It was studied construction panels of prismatic silo for powder industry, with zigzag conformation and a slope of 20° from the vertical plan to increase the wall inertia and do not accumulate powder, that it would cause deterioration and/or infestation of fungus and bacterias that would contaminate the powder resulting economical damage to manufacture and animal criator. lt was done tests in to determine the rigidity and strength of the panels in full scale, that will make up the formed prismatic silo wall for modular construction. The experimental results were compared to simplified theories proposed to structural calculations of silos, and to the results given by the LUSA software which utilities finites elements. These comparations showed that the theory of TROITSKY (1988) presents a good correlation, and so it is suitable for the panel design.
14

Dokumentace Zadního paláce na hradě Veveří / Geodetic Survey of the Rear Palace of the Veveří Castle

Gabrlík, Marek January 2018 (has links)
The purpose of my diploma thesis is geodetic survey and creation of the drawing documentation of the first two above-ground floors of the rear palace, four above-ground floors of the adjacent prismatic tower and the facades of the two assigned objects accessible from the courtyard. The geodetic survey was made in connection with the previous measurements of the neighboring English tract by the combination of the polar and the standard measures. The calculation of the obtained data was done in Groma and the required drawings were made in Microstation. The result of my thesis is the drawing documentation consists of four plans, longitudinal section, cross section and two views.
15

Crystalline Condition for Ainf-cohomology and Ramification Bounds

Pavel Coupek (12464991) 27 April 2022 (has links)
<p>For a prime p>2 and a smooth proper p-adic formal scheme X over O<sub>K</sub> where K is a p-adic field of absolute ramification degree e, we study a series of conditions (Cr<sub>s</sub>), s>=0 that partially control the G<sub>K</sub>-action on the image of the associated Breuil-Kisin prismatic cohomology RΓ<sub>Δ</sub>(X/S) inside the A<sub>inf</sub>-prismatic cohomology RΓ<sub>Δ</sub>(X<sub>Ainf</sub>/A<sub>inf</sub>). The condition (Cr<sub>0</sub>) is a criterion for a Breuil-Kisin-Fargues G<sub>K</sub>-module to induce a crystalline representation used by Gee and Liu, and thus leads to a proof of crystallinity of H<sup>i</sup><sub>et</sub>(X<sub>CK</sub>, Q<sub>p</sub>) that avoids the crystalline comparison. The higher conditions (Cr<sub>s</sub>) are used in an adaptation of a ramification bounds strategy of Caruso and Liu. As a result, we establish ramification bounds for the mod p representations H<sup>i</sup><sub>et</sub>(X<sub>CK</sub>, Z/pZ) for arbitrary e and i, which extend or improve existing bounds in various situations.</p>
16

Fragilisation des aciers de cuve irradiés : analyse numérique des mécanismes de plasticité à l’aide de simulations de dynamique des dislocations / Dose-dependent embrittlement in nuclear reactor pressure vessel steel : dislocation-mediated plasticity mechanisms analyzed by means of 3D dislocation dynamics simulations

Li, Yang 27 September 2019 (has links)
Ce travail est une contribution à l’étude de la dégradation des propriétés mécaniques des matériaux métalliques irradiés, dans le contexte de la production d’énergie nucléaire. Cette thèse porte en particulier sur l’étude du comportement des dislocations dans les matériaux ferritiques irradiés, à l’aide de simulations de dynamique des dislocations (DD).L’évolution de la microstructure des défauts d’irradiation est tout d’abord analysée à l'aide d’un code nodal (code NUMODIS). Le Chapitre 2 traite en particulier de la diffusion et l’interaction de boucles prismatiques, en utilisant la dynamique des dislocations dite «stochastique». Ces calculs reproduisent les forces d’interaction élastiques boucle/boucle et les forces stochastiques associées aux fluctuations thermiques ambiantes. Il est ainsi montré que la réorientation des boucles (tilt) a un fort effet sur leur dynamique, en ce qui concerne notamment le taux d’évolution du confinement élastique boucle/boucle.L'effet du glissement dévié sur l’interaction entre dislocation/boucle est ensuite examiné au Chapitre 3. Cette étude fait appel à une configuration initiale spécifique, associée à un changement du plan de glissement d'une source de dislocation vis. De cette manière, il est montré que le glissement dévié réduit considérablement la résistance des défauts/obstacles. Cet effet confirme le rôle critique du glissement dévié durant la déformation plastique post-irradiation.La déformation plastique post-irradiation est étudiée à l’échelle du grain, au Chapitre 4, à l’aide de simulations DD à base de segments (code TRIDIS). Ces simulations traitent les mécanismes de glissement dévié et de glissement thermiquement activé (vis). Chaque condition d’irradiation simulée peut être caractérisée par un «décalage de la température apparente induite par des défauts d’irradiation» (ΔDIAT). Cette quantité est proportionnelle aux évolutions statistiques de la mobilité effective des dislocations. Le ΔDIAT calculé est pratiquement équivalent au décalage de la température de transition fragile à ductile (ΔDBTT) obtenu expérimentalement, pour une taille et densité de défauts d’irradiation donnée. Cette corrélation ΔDIAT/ΔDBTT peut être interprétée à partir de mécanismes de déformation plastique élémentaires, faisant appel à la théorie des dislocations. / The interplay between radiation-generated defects and dislocation networks leads to a variety of changes in mechanical properties and results in a detrimental effect on the structural reactor component lifetime. The present PhD work focuses on studying elementary and collective dislocation mechanisms in irradiated iron-based materials, by means of dislocation dynamics (DD) simulations.Evolutions of the radiation-induced defect microstructure are studied first. Namely, the 1D diffusion of interacting prismatic loops is analyzed using the stochastic dislocation dynamics approach, accounting for the elastic forces acting between the loops and the stochastic forces associated with ambient thermal fluctuations. It is found that the interplay between stochastic forces and internal degrees of freedom of loops, in particular the loop reorientation, strongly influences the observed loop dynamics, especially the reaction rates resulting in the elastic confinement of loops.The cross-slip effect on the dislocation/loop interactions is then examined using a specific initial configuration associated with the glide plane change of a screw dislocation source, due to a single and well defined cross-slip event. It is shown that cross-slip significantly affects the effective strength of dislocation/defect interactions and therefore, post-irradiation plastic strain spreading.Lastly, post-irradiation plastic strain spreading is investigated at the grain scale using segment-based dislocation dynamics simulations, accounting for the thermally activated (screw) dislocation slip and cross-slip mechanisms. It is shown that each simulated irradiation condition can be characterized by a specific “Defect-Induced Apparent Straining Temperature shift” (ΔDIAT) level, reflecting the statistical evolutions of the effective dislocation mobility. It is found that the calculated ΔDIAT level closely matches the ductile to brittle transition temperature shift (ΔDBTT) associated with the corresponding, experimentally-observed defect size and number density. This ΔDIAT/ΔDBTT correlation can be explained based on plastic strain spreading arguments.
17

Synthesis Techniques for Coupler-Driven Planar and Spherical Single Degree of Freedom Mechanisms

Perkins, David A. 08 November 2011 (has links)
No description available.
18

Modified ParaDex: Theory and hardware implementation of a 6-prismatic-spherical-universal parallel manipulator

Hopkins, Brian January 2001 (has links)
No description available.
19

Industrialization of Lithium-Ion Prismatic Battery Cell for the Automotive Industry

Liiv, Oliver January 2020 (has links)
Energy systems in every part of the world are experiencing accelerated shifts towards more sustainable solutions which will bring far-reaching changes to our daily lives. These rapid transitions will bring impactful and vital changes to the way we fuel our cars, heat our homes and power our industries in the approaching decades. [1] The automotive sector is in high pace to electrify their cars. The number of electric passengercar sales is expected to increase by more than a factor of 60 between 2018 to 2050. Which means by that time there could be approximately 2 billion EVs on the roads and they all need batteries to run on. [1] ManyEuropean electric vehicle manufacturers have started marketing their future models globally, but automotiveli.-ion battery manufacturing capacity in Europe is merely 2.1% of the total global automotive li-ion batteryproduction. [2] Increase in sales of EV-s and energy storage systems drives the demand for li-ion batteries. This research is conducted in collaboration with Northvolt, one of the newcomers to the li-ion batterymanufacturing market in Europe. Northvolt is a Swedish-founded company in 2016, and despite its young age, Northvolt has prominent partners including BMW Group, Epiroc, Scania and the Volkswagen Group. Northvolt is with global ambition to produce the world's greenest battery cell with minimal possible carbon footprint in its Gigafactory in Sweden with 32GWh annual manufacturing capacity. Also, together with Volkswagen a 50/50 joint venture has been established to produce batteries in a 16GWh factory in Germany. After entering in different supplier agreements, Northvolt has sold a considerable amount of its first Gigafactory NV Ett production capacity to its key customers with a united equivalent of over $13billion until 2030. [3]Setting up lithium-ion battery factories for the automotive industry is a challenging task. It requires high speed and flexibility to keep up with the growing demand in a short time and still meeting all the stakeholder's requirements while keeping the highest environmental standards in place during production. To keep up with the growing demand and customer requirements a state-of.the-art industrialization project management strategy is developed. Therefore, state-of.the-art automotive project management, new product industrialization and development practices are investigated together with the best practices from the wider industry. Furthermore, Northvolt's current industrialization project management strategies are examined, and improvement proposals and tools are developed to ramp-up the current and future factories with shorter time, less cost and highest possible quality. The main aim of the thesis is to develop a project management solutions to lead industrialization of li-ionbattery Giga-factories successfully and help Northvolt fuel our cars, heat our homes, and power our industries more sustainably and innovatively. The expected outcome of the thesis is five tools developed that support the industrialization of LIB production facilities in Europe to increase the EU LIB manufacturing capacity. / Energisystem genomgår en snabb omväxling till allt mer hållbara lösningar, vilket kommer påverka våra liv markant. Dessa snabba omväxlingar kommer påverka samt främja sättet hur vi driver våra bilar, värmer våra hus och försörjer våra industrier, flera år framåt. [1] Bilsektorn som har skiftat sitt fokus till elektrifiering av sina bilar, där antalet sålda elbilar förväntas att öka sextifaldigt mellan 2018 och 2050. Detta kommer att leda till att cirka 2 miljarder elbilar kommer att åka på vägarna globalt och alla dessabilar kommer behöva framförallt litiumjonbatterier. [1] Majoriteten av biltillverkare i Europa har börjatutveckla framtida elektrifierade bilmodeller. Tillverkningen av litiumjonbatterier för elbilar i Europa utgörendast 2.1 % av den globala tillverkningen totalt. [2] En ökad försäljning av elbilar och även av produkterför energilagring, ökar efterfrågan på litiumjonbatterier. Den här undersökningen har tagits fram i samarbete med Northvolt som är en av nykomlingarna inomtillverkningen av litiumjonbatterier i Europa. Northvolt är ett svenskt bolag som startades 2016 och trotsdess tidiga fas, har de lyckats samverka med prominenta samarbetspartners som BMW group, Epiroc, Scania och Volkswagen group. Northvolts ambition är att skapa världens grönaste batteri med ett minimalt klimatavtryck. Denna produkt utvecklas i deras så kallade Gigafactory som ligger i Skellefteå och vars årliga produktion uppnår 32 Gwh. Utöver det har Northvolt i samarbete med Volkswagen fått i uppdrag att bygga upp en batterifabrik i Tyskland, vars tillverkningskapacitet kommer att uppnå till 16Gwh årligen. Efter att ha ingått i flera leverantörsavtal har Northvolt sålt en avsevärd mängd av sin produktionskapacitet för den planerade fabriken Gigafactory NV Ett till sina nyckelkunder. Detta motsvarar en investering på 13 miljarder dollar fram till 2030. [3]Att etablera en fabrik som tillverkar litiumjonbatterier för bilindustrin är en utmanande uppgift. Det kräversnabba beslut och flexibilitet för att hålla jämna steg med den växande efterfrågan på batterier av denna typ. Batterierna ska hålla måttet för de krav som kunderna har, och även ska de uppfylla alla internationella standarder för ett miljövänligt batteri.För att kunna upprätthålla den växande efterfrågan och kundkraven utvecklas nya metoder inom projektledning för att effektivisera produktionen. Det allra senaste praxis i projektledning, produktion och produkttillverkning inom bilindustrin analyseras. Dessutom beaktas senaste metoderna och praxis från andra industrier. Vidare kartläggs northvolts nuvarande strategi för deras hantering av produktionsfasen för att föreslå förbättringar och verktyg, som kan effektivisera uppbyggnaden och driften av framtida fabriker. Huvudsyftet med denna avhandling är att utveckla nya metoder inom projektledning för att kunnautveckla produktionsfasen för framtida fabriker som tillverkar litiumjonbatterier. Detta kommer leda tillatt Northvolt kommer vara en del av våra framtida liv genom att hjälpa oss att driva våra fordon, värma våra hem och driva våra fabriker på ett hållbart och effektivt sätt. Det förväntade resultatet i denna avhandling är fem utvecklade verktyg som stödjer utbyggnaden av Litiumjonbatteri fabriker i Europa föratt öka dess totala årliga produktion.
20

Unstructured mesh methods for stratified turbulent flows

Zhang, Zhao January 2015 (has links)
Developments are reported of unstructured-mesh methods for simulating stratified, turbulent and shear flows. The numerical model employs nonoscillatory forward in-time integrators for anelastic and incompressible flow PDEs, built on Multidimensional Positive Definite Advection Transport Algorithm (MPDATA) and a preconditioned conjugate residual elliptic solver. Finite-volume spatial discretisation adopts an edge-based data structure. Tetrahedral-based and hybrid-based median-dual options for unstructured meshes are developed, enabling flexible spatial resolution. Viscous laminar and detached eddy simulation (DES) flow solvers are developed based on the edge-based NFT MPDATA scheme. The built-in implicit large eddy simulation (ILES) capability of the NFT scheme is also employed and extended to fully unstructured tetrahedral and hybrid meshes. Challenging atmospheric and engineering problems are solved numerically to validate the model and to demonstrate its applications. The numerical problems include simulations of stratified, turbulent and shear flows past obstacles involving complex gravity-wave phenomena in the lee, critical-level laminar-turbulence transitioning and various vortex structures in the wake. Qualitative flow patterns and quantitative data analysis are both presented in the current study.

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