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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

Novel Approaches to Cell Isolation in Simple Inertial Microfluidic Devices

Zhou, Jian 30 October 2012 (has links)
No description available.
72

Sistema supervis?rio para po?os de petr?leo baseados no m?todo de eleva??o artificial Plunger Lift

Soares, Lennedy Campos 22 March 2010 (has links)
Made available in DSpace on 2014-12-17T14:08:46Z (GMT). No. of bitstreams: 1 LennedyCS_DISSERT.pdf: 3653783 bytes, checksum: 8a237d13a56a26f3a6ff1bf8c63bdede (MD5) Previous issue date: 2010-03-22 / The several existing methods for oil artificial lifting and the variety of automation equipment for these methods many times lead the supervisory systems to be dedicated to a unique method and/or to a unique manufacturer. To avoid this problem, it has been developed the supervisory system named SISAL, conceived to supervise wells with different lifting methods and different automation equipments. The SISAL system is working in several Brazilian states but, nowadays, it is only supervising rod pump-based wells. The objective of this work is the development of a supervision module to the plunger lift artificial lift method. The module will have the same characteristics of working with automation hardware of many manufacturers. The module will be integrated to the SISAL system, incorporating the capacity to supervise the plunger lift artificial lift method. / Os v?rios m?todos de eleva??o artificial de petr?leo e os diferentes equipamentos de automa??o existentes muitas vezes levam a que os sistemas supervis?rios sejam dedicados a um ?nico m?todo e/ou a um ?nico fabricante de equipamentos. Para contornar este problema, foi desenvolvido o sistema SISAL, capaz de supervisionar po?os com diferentes m?todos de eleva??o e equipamentos de automa??o. Atualmente, o SISAL est? em opera??o em diversos po?os em v?rios estados do Brasil, supervisionando po?os de bombeio mec?nico. O objetivo deste trabalho ? desenvolver um m?dulo de supervis?o para o m?todo de eleva??o artificial plunger lift, com as mesmas caracter?sticas de poder trabalhar com hardwares de automa??o de diferentes fabricantes. O m?dulo desenvolvido ser? integrado ao SISAL, de forma a incorporar ao sistema a capacidade de supervisionar este novo m?todo de eleva??o.
73

Simulador computacional do comportamento em regime de po?os de petr?leo equipados com gas-lift cont?nuo / Simulador computacional do comportamento em regime de po?os de petr?leo equipados com gas-lift cont?nuo / Simulador computacional do comportamento em regime de po?os de petr?leo equipados com gas-lift cont?nuo / Simulador computacional do comportamento em regime de po?os de petr?leo equipados com gas-lift cont?nuo

Moura, Ewerton Alexandre Pinheiro de 17 November 2004 (has links)
Made available in DSpace on 2014-12-17T14:56:04Z (GMT). No. of bitstreams: 1 EwertonAPM.pdf: 3120304 bytes, checksum: ff33c0c9ca20630c0130f326f67a029e (MD5) Previous issue date: 2004-11-17 / Amongst the results of the AutPoc Project - Automation of Wells, established between UFRN and Petrobras with the support of the CNPq, FINEP, CTPETRO, FUNPEC, was developed a simulator for equipped wells of oil with the method of rise for continuous gas-lift. The gas-lift is a method of rise sufficiently used in production offshore (sea production), and its basic concept is to inject gas in the deep one of the producing well of oil transform it less dense in order to facilitate its displacement since the reservoir until the surface. Based in the use of tables and equations that condense the biggest number of information on characteristics of the reservoir, the well and the valves of gas injection, it is allowed, through successive interpolations, to simulate representative curves of the physical behavior of the existing characteristic variable. With a simulator that approaches a computer of real the physical conditions of an oil well is possible to analyze peculiar behaviors with very bigger speeds, since the constants of time of the system in question well are raised e, moreover, to optimize costs with assays in field. The simulator presents great versatility, with prominance the analysis of the influence of parameters, as the static pressure, relation gas-liquid, pressure in the head of the well, BSW (Relation Basic Sediments and Water) in curves of request in deep of the well and the attainment of the curve of performance of the well where it can be simulated rules of control and otimization. In moving the rules of control, the simulator allows the use in two ways of simulation: the application of the control saw software simulated enclosed in the proper simulator, as well as the use of external controllers. This implies that the simulator can be used as tool of validation of control algorithms. Through the potentialities above cited, of course one another powerful application for the simulator appears: the didactic use of the tool. It will be possible to use it in formation courses and recycling of engineers / Dentre os resultados do Projeto AutPoc – Automa??o de Po?os, estabelecido entre UFRN e Petrobras com o apoio do CNPq, FINEP, CTPETRO, FUNPEC, foi desenvolvido um simulador para po?os de petr?leo equipados com o m?todo de eleva??o por gas-lift cont?nuo. O gas-lift ? um m?todo de eleva??o bastante utilizado em produ??o offshore (produ??o marinha), e seu conceito fundamental ? injetar g?s no fundo do po?o produtor de petr?leo tornando-o menos denso de modo a facilitar seu deslocamento desde o reservat?rio at? a superf?cie. Baseado na utiliza??o de tabelas e equa??es que condensam o maior n?mero de informa??es sobre caracter?sticas do reservat?rio, do po?o e das v?lvulas de inje??o de g?s, ? permitido, atrav?s de sucessivas interpola??es, simular curvas representativas do comportamento f?sico das vari?veis caracter?sticas existentes. Com um simulador que aproxime um computador das condi??es f?sicas reais de um po?o de petr?leo ? poss?vel analisar comportamentos peculiares com velocidades muito maiores, visto que as constantes de tempo do sistema em quest?o s?o bem elevadas e, al?m disso, otimizar custos com ensaios em campo. O simulador apresenta grande versatilidade, destacadamente a an?lise da influ?ncia de par?metros, como a press?o est?tica, raz?o g?s-l?quido, press?o na cabe?a do po?o, BSW (Basic Sediments and Water) em curvas de solicita??o no fundo do po?o e a obten??o da curva de desempenho do po?o onde pode-se simular regras de controle e otimiza??o. No tocante as regras de controle, o simulador permite a utiliza??o em dois modos de simula??o: a aplica??o do controle via software simulado inclu?do no pr?prio simulador, bem como a utiliza??o de controladores externos. Isto implica que o simulador pode ser utilizado como ferramenta de valida??o de algoritmos de controle. Atrav?s das potencialidades acima citadas, naturalmente surge uma outra poderosa aplica??o para o simulador: a utiliza??o did?tica da ferramenta. Ser? poss?vel utiliz?-lo em cursos de forma??o e reciclagem de engenheiros
74

Modelagem din?mica do escoamento de um sistema de eleva??o por plunger lift

Assmann, Felipe Pinheiro Mota 18 April 2012 (has links)
Made available in DSpace on 2014-12-17T14:58:17Z (GMT). No. of bitstreams: 1 FelipePMA_DISSERT.pdf: 3715487 bytes, checksum: 630bbbaabad6ec787270701f99c61fb0 (MD5) Previous issue date: 2012-04-18 / A critical problem in mature gas wells is the liquid loading. As the reservoir pressure decreases, gas superficial velocities decreases and the drag exerted on the liquid phase may become insufficient to bring all the liquid to the surface. Liquid starts to drain downward, flooding the well and increasing the backpressure which decreases the gas superficial velocity and so on. A popular method to remedy this problem is the Plunger Lift. This method consists of dropping the "plunger"to the bottom of the tubing well with the main production valve closed. When the plunger reaches the well bottom the production valve is opened and the plunger carry the liquid to the surface. However, models presented in literature for predicting the behavior in plunger lift are simplistic, in many cases static (not considering the transient effects). Therefore work presents the development and validation of a numerical algorithm to solve one-dimensional compressible in gas wells using the Finite Volume Method and PRIME techniques for treating coupling of pressure and velocity fields. The code will be then used to develop a dynamic model for the plunger lift which includes the transient compressible flow within the well / Um problema cr?tico em po?os maduros de g?s ? a carga l?quida. Quando a press?o do reservat?rio diminui, a velocidade superficial diminui e o arrasto exercido na fase l?quida pode se tornar insuficiente para trazer todo o l?quido para a superf?cie. O l?quido come?a a drenar para baixo, afogando o po?o e aumentando a contrapress?o, a qual diminui a velocidade superficial, e assim por diante. Um m?todo popular para remediar esse problema ? o plunger lift. Esse m?todo consiste em derrubar um plunger na fundo coluna de produ??o com a v?lvula principal fechada. Quando o plunger alcan?a o fundo do po?o a v?lvula de produ??o ? aberta e o plunger carrega o l?quido para a superf?cie. Atualmente, os modelos presentes na literatura para prever o comportamento do plunger s?o simplistas, em muitos casos est?ticos (n?o consideram efeitos transientes). Assim, esse trabalho apresenta e valida um algor?timo num?rico para resolver escoamentos em po?os de g?s usando o M?todo dos Volumes Finitos e a t?cnica PRIME para tratar o acoplamento da press?o e velocidade. Esse modelo ser? usado para desenvolver modelos din?micos para plunger lift que incluem efeitos transientes e compress?veis nos escoamentos em po?os
75

Návrh nákladního výtahu / Project of service lift

Nguyen, Huy Long Unknown Date (has links)
Task of this diploma thesis is to design service lift which is driven by unordinary mechanism using thrust chain. Main parts of this diploma are design and description of main construction parts, strength analysis and drive design.
76

Estudo do comportamento dinâmico de válvula de gas-lift de fole carregado e operada por pressão utilizando a fluidodinâmica computacional / STUDY OF THE DYNAMIC OF GAS VALVE LIFT-BORN OF BELLOWS AND OPERATED PRESSURE USING A COMPUTATIONAL FLUID DYNAMICS.

Valadares, Enaldo Cezar Santana 30 March 2010 (has links)
This work presents the result achieved through investigation of RH-2 gas-lift valve dynamic performance. It is an unbalanced gas-lift valve injection pressure operated, for high injection pressure applications. First, a CFD model was developed in order to obtain the valve orifice flow pattern performance curve. The CFD curve was compared with the curve experimentally obtained, conceiving very promising results. A test bench, and the necessary test devices, have been projected and built looking forward to determine the bellows load rate. Second, a CFD mesh deformation model was developed, which allowed the determination of dynamic performance curves on orifice, transition and throttling flow patterns for a given bellows pressure. The accuracy of the mesh deformation model was verified comparing the obtained curve with experimental results. The results of numerous CFD model simulations allowed to correlate data and to find a transition pressure, the production pressure for the maximum gas throughput and the product of the discharge coefficient by the expansion factor. The mathematical model developed allows predicting the gas throughput capacity of the gas-lift valve using injection pressure, production pressure and bellows pressure, for a defined load rate and a defined port diameter. / Nos primeiros estágios de produção, um poço de petróleo apresenta um fluxo natural, sendo a energia necessária para elevação dos fluidos até a superfície fornecida pelo próprio reservatório. Neste caso, diz-se que o poço é surgente. Entretanto, na medida em que as reservas são produzidas, a pressão do reservatório diminui e surge a necessidade de complementar artificialmente a energia requerida para a elevação. Diz-se, então, que o poço produz por elevação artificial. De todos os métodos de elevação artificial, o gas lift é o mais amplamente utilizado, e para a sua implementação são requeridas as chamadas válvulas de gas lift. O conhecimento do comportamento dinâmico da válvula de gas lift é fundamental na etapa de projeto e no estabelecimento de estratégias operacionais eficientes. Este trabalho apresenta os resultados obtidos no estudo do desempenho dinâmico da válvula de gas-lift RH-2, a qual consiste em uma válvula de gas lift não balanceada operada por pressão e de alta pressão de carregamento no fole, fabricada pela Weatherford, e que não dispõe de um modelo para o levantamento de suas curvas de desempenho dinâmico. Inicialmente, foi desenvolvido um modelo fluidodinâmico utilizando-se Dinâmica de Fluidos Computacional (CFD) para a obtenção da curva de desempenho no regime de orifício e este foi comparado com dados obtidos experimentalmente, produzindo resultados muito promissores. Uma bancada de testes com os dispositivos necessários foi projetada e construída para o levantamento da taxa de carga do fole. A seguir, foi desenvolvido um modelo fluidodinâmico da válvula no aplicativo CFX, utilizando uma malha deformável, que permitiu a geração das curvas de desempenho nos regimes de orifício, transição e estrangulamento para uma dada pressão de carregamento do fole. A precisão da malha deformável foi verificada comparando a curva obtida para diversas posições da haste com resultados experimentais. Os resultados das várias simulações do modelo fluidodinâmico permitiram correlacionar dados e calcular a pressão de transição, a pressão de produção onde ocorre a vazão máxima e o produto do coeficiente de descarga pelo fator de expansão. O modelo matemático desenvolvido permite predizer a vazão de gás que escoa pela válvula de gas lift a partir da pressão de injeção, da pressão de produção e da pressão de carregamento no fole, para uma taxa de carga do fole e um diâmetro de porta definidos.
77

Řízení modelu výtahu s průmyslovou sběrnicí AS-Interface / Control of lift model with the fieldbus AS-Interface

Goryl, Stanislav January 2014 (has links)
The aim of the master thesis is to create and verify the control algorithm of a personal lift. First part of the thesis focuses on a literature review investigating the requirements for personal lifts. Based on the information found in the review, selected measures were implemented in the model so that it would be the most suitable to the requirements for personal lifts. A brief introduction of the lift and its norms is followed by a description of the programme and control algorithm, including the description of the used add-on instructions. Last part describes the visualization which is used to control the lift model. In addition to controlling, the visualization provides statistical data, the current status of the programme and information about the set parameters, inputs, outputs and faults.
78

Development and analysis of turbulence models for flows with strong curvature and rotation

Grundestam, Olof January 2004 (has links)
<p>An explicit algebraic Reynolds stress model (EARSM) based ona pressure strain rate model including terms tensoriallynonlinear in the mean velocity gradients is developed in orderto improve predictions for .ows with strong curvature and/orrotation. This work has been carried out in the context of acollaborative international project on high-lift aerodynamics.For 2D mean .ows the nonlinear terms can easily be accountedfor in the model formulation. This is not the case for 3D mean.ows and approximations making the 2D and 3D mean .owformulations consistent are suggested. The proposed EARSM, theparent-EARSM and the corresponding di.erential Reynolds stressmodels (DRSM) are tested for spanwise rotating channel .ow andaxially rotating pipe .ow. The model predictions are comparedto experimental and DNS data. The nonlinear extensions areshown to have a signi.cant e.ect on the .ow predictions,somewhat less pronounced for the DRSM though. The turbulentdi.usion modelling in the EARSM computations is important forthe rotating pipe. It is shown that by using a Daly and Harlowdi.usion model, turbulence levels in good agreement withexperiments and DRSM can be achieved. However, by using asimpler e.ective eddy viscosity based di.usion model theturbulence kinetic energy levels are drastically overpredicted.Finally the proposed EARSM is tested on a standard high-liftcon.guration. The EARSM predictions are compared withexperiments and the predictions made by the standard K - ωtwo-equation model.</p><p><b>Descriptors:</b>Turbulence model, nonlinear modelling,streamline curvature, high-lift aerodynamics.</p>
79

A truncation error injection approach to viscous-inviscid interaction.

Goble, Brian Dean. January 1988 (has links)
A numerical procedure is presented which uses the truncation error injection methodology to efficiently achieve accurate approximations to complex problems having disparate length scales in the context of solving viscous, transonic flow over an airfoil. The truncation error distribution is estimated using the solution on a coarse grid. Local fine grids are formed which improve the resolution in regions of large truncation error. A fast fourth-order accurate scheme is presented for interpolating and relating the solutions between the generalized curvilinear coordinate systems of the local and global grids. It is shown that accurate solutions can be obtained on a global coarse grid with correction information obtained on local fine grids, which may or may not be topologically similar to the global grid as long as they are capable of resolving the local length scale. Dirichlet boundary conditions for the local grid yield the best results. The scheme also serves as the basis of a local refinement technique wherein a grid local to the nose of an airfoil is used to resolve a supersonic zone terminated by a shock and its interaction with a turbulent boundary layer. The solution on the local grid reveals details of the shock structure and a jet-like flow emanating from the root of the normal shock in the shock boundary layer interaction zone.
80

Pedestrian Protection System : Hood lift study / Fotgängarskydd : Konceptstudie för huvlyft

Abdallah, Kristian January 2015 (has links)
Every year approximately 400 000 pedestrians are killed worldwide in road related injuries where children and elderly are the most exposed age groups. The design of the front-end of a vehicle and the structural stiffness have a significant influence on the kinematics and injury risks of the pedestrian body. To create a clearance between the rigid hood structure and the hood, the hood is lifted. A lifted hood does however not provide protection over the cowl, windscreen and A-pillar areas. This study is performed at Autoliv Sverige AB and the purpose is to examine how fast the hood can be lifted 100 mm using a pedestrian protection airbag. The airbag give an extended protection while covering the cowl, windscreen and A-pillar areas. A concept generation session was performed where modifications of the current pedestrian protection airbag, for a faster hood lift, were proposed. The generated concepts proceeded to a concept screening session where the Autoliv evaluation matrix was used. The selected concepts went further to static testing where the performance of each concept was tested. The performance include the lift time of 100 mm for the most rearward section of the hood, positioning of the cushion and pressure distribution. The tests were carried out in a room temperature environment. To conclude the thesis work, one winning concept could not be obtained. Two concepts excelled themselves from all the concepts and a difference in the performances between these two concepts could not be found. In this thesis no calculations on costs such as material costs and manufacturing costs has been made. This can be the major aspect on choosing one winning concept but due to the fact that there is no time for a cost analysis in this thesis, the PPA development team will take over.

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