Tesis sobre el tema "Mixed scheme"
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Dimagiba, Richard Raymond N. "Application of the Boundary Element Method to three-dimensional mixed-mode elastoplastic fracture mechanics". Thesis, University of Sheffield, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.310815.
Texto completoToner, Michael F. "MADBIST : a scheme for built-in self-test of mixed analog-digital integrated circuits". Thesis, McGill University, 1996. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=40451.
Texto completoHanson, Coral Lucy. "Advancing understanding of effective exercise on referral : a mixed methods evaluation of the Northumberland scheme". Thesis, Durham University, 2017. http://etheses.dur.ac.uk/12162/.
Texto completoMills, Hayley. "A mixed method investigation into the perception and measurement of success in the Healthwise Exercise Referral Scheme". Thesis, University of Gloucestershire, 2008. http://eprints.glos.ac.uk/3173/.
Texto completoOwusu-Asamoah, Kwasi. "Modelling an information management system for the National Health Insurance Scheme in Ghana". Thesis, Loughborough University, 2014. https://dspace.lboro.ac.uk/2134/16415.
Texto completoJeong, Minsoo. "Asymptotics for the maximum likelihood estimators of diffusion models". [College Station, Tex. : Texas A&M University, 2008. http://hdl.handle.net/1969.1/ETD-TAMU-2335.
Texto completoSchütz, Jochen [Verfasser]. "A hybrid mixed finite element scheme for the compressible Navier-Stokes equations and adjoint-based error control for target functionals / Jochen Schütz". Aachen : Hochschulbibliothek der Rheinisch-Westfälischen Technischen Hochschule Aachen, 2011. http://d-nb.info/1018186158/34.
Texto completoHurst, Gemma Louise. "'Walk to Beijing' : a mixed methods evaluation of a financial incentive scheme aimed at encouraging physical activity participation in Sandwell, West Midlands". Thesis, Staffordshire University, 2013. http://eprints.staffs.ac.uk/2003/.
Texto completoMalik, Muhammad Usman. "Learning multimodal interaction models in mixed societies A novel focus encoding scheme for addressee detection in multiparty interaction using machine learning algorithms". Thesis, Normandie, 2020. http://www.theses.fr/2020NORMIR18.
Texto completoHuman -Agent Interaction and Machine learning are two different research domains. Human-agent interaction refers to techniques and concepts involved in developing smart agents, such as robots or virtual agents, capable of seamless interaction with humans, to achieve a common goal. Machine learning, on the other hand, exploits statistical algorithms to learn data patterns. The proposed research work lies at the crossroad of these two research areas. Human interactions involve multiple modalities, which can be verbal such as speech and text, as well as non-verbal i.e. facial expressions, gaze, head and hand gestures, etc. To mimic real-time human-human interaction within human-agent interaction,multiple interaction modalities can be exploited. With the availability of multimodal human-human and human-agent interaction corpora, machine learning techniques can be used to develop various interrelated human-agent interaction models. In this regard, our research work proposes original models for addressee detection, turn change and next speaker prediction, and finally visual focus of attention behaviour generation, in multiparty interaction. Our addressee detection model predicts the addressee of an utterance during interaction involving more than two participants. The addressee detection problem has been tackled as a supervised multiclass machine learning problem. Various machine learning algorithms have been trained to develop addressee detection models. The results achieved show that the proposed addressee detection algorithms outperform a baseline. The second model we propose concerns the turn change and next speaker prediction in multiparty interaction. Turn change prediction is modeled as a binary classification problem whereas the next speaker prediction model is considered as a multiclass classification problem. Machine learning algorithms are trained to solve these two interrelated problems. The results depict that the proposed models outperform baselines. Finally, the third proposed model concerns the visual focus of attention (VFOA) behaviour generation problem for both speakers and listeners in multiparty interaction. This model is divided into various sub-models that are trained via machine learning as well as heuristic techniques. The results testify that our proposed systems yield better performance than the baseline models developed via random and rule-based approaches. The proposed VFOA behavior generation model is currently implemented as a series of four modules to create different interaction scenarios between multiple virtual agents. For the purpose of evaluation, recorded videos for VFOA generation models for speakers and listeners, are presented to users who evaluate the baseline, real VFOA behaviour and proposed VFOA models on the various naturalness criteria. The results show that the VFOA behaviour generated via the proposed VFOA model is perceived more natural than the baselines and as equally natural as real VFOA behaviour
Hao, Chengcheng. "Explicit Influence Analysis in Crossover Models". Doctoral thesis, Stockholms universitet, Statistiska institutionen, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-107703.
Texto completoMoore, Graham Francis. "Developing a mixed methods framework for process evaluations of complex interventions : the case of the National Exercise Referral Scheme Policy Trial in Wales". Thesis, Cardiff University, 2010. http://orca.cf.ac.uk/55051/.
Texto completoBinous, Mohamed Sabeur. "Simulations numériques d'écoulements anisothermes turbulents : application à la cavité ventilée". Thesis, Perpignan, 2017. http://www.theses.fr/2017PERP0031/document.
Texto completoThe aim of this work is about a numerical study of anisothermal incompressible flowsconfined in a cavity. We perform a modeling of heat transfer in a wall where one of its faces iscovered with a thin layer of phase change material (PCM). This modeling is based on aSignorini boundary condition. The transfer equations are solved by a specific iterativeprocedure. This procedure is then applied to a differentially heated cavity, one of the walls ofwhich is covered with a thin layer of PCM. The transfer equations are solved by a semi-implicit method with finite second order differences and the projection algorithm. We validatethe procedure by applying it to the lid-driven cavity, downward motion, flow around a squaresection bar and natural convection in a differentially heated cavity. In a second step, the studyof incompressible turbulent flows in a ventilated cavity was carried out using a parallel highprecision solver developed at LAMPS. The transfer equations are solved by a finite differencecompact scheme and the projection algorithm. It is shown in particular that the heat flowapplied to the lower wall of the cavity greatly influences the structure of the flow and the heattransfers, as well as the mean and fluctuating fields of velocity and temperature
Ramos, Reynaldo Perez. "Analysis of mixed-use schemes in regeneration areas". Thesis, Ulster University, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.675930.
Texto completoDemay, Charles. "Modélisation et simulation d'écoulements transitoires diphasiques eau-air dans les circuits hydrauliques". Thesis, Université Grenoble Alpes (ComUE), 2017. http://www.theses.fr/2017GREAM100/document.
Texto completoThe present work is dedicated to the mathematical and numerical modelling of transient air-water flows in pipes which occur in piping systems of several industrial areas such as nuclear or hydroelectric power plants or sewage pipelines. It deals more specifically with the so-called mixed flows which involve stratified regimes driven by slow gravity waves, pressurized or dry regimes (pipe full of water or air) driven by fast acoustic waves and entrapped air pockets. An accurate modelling of these flows is necessary to guarantee the operability of the related hydraulic system. While most of available models in the literature focus on the water phase neglecting the air phase, a compressible two-layer model which accounts for air-water interactions is proposed herein. The derivation process relies on a depth averaging of the isentropic Euler set of equations for both phases where the hydrostatic constraint is applied on the water pressure gradient. The resulting system is hyperbolic and satisfies an entropy inequality in addition to other significant mathematical properties, including the uniqueness of jump conditions and the positivity of heights and densities for each layer. Regarding the discrete level, the simulation of mixed flows with the compressible two-layer model raises key challenges due to the discrepancy of wave speeds characterizing each regime combined with the fast underlying relaxation processes and with phase vanishing when the flow becomes pressurized or dry. Thus, an implicit-explicit fractional step method is derived. It relies on the fast pressure relaxation in addition to a mimetic approach with the shallow water equations for the slow dynamics of the water phase. In particular, a relaxation method provides stabilization terms activated according to the flow regime. Several test cases are performed and attest the ability of the compressible two-layer model to deal with mixed flows in pipes involving air pocket entrapment
Kheriji, Walid. "Méthodes de correction de pression pour les équations de Navier-Stokes compressibles". Phd thesis, Université de Provence - Aix-Marseille I, 2011. http://tel.archives-ouvertes.fr/tel-00804116.
Texto completoShi, Chen Yang. "High order compact schemes for fractional differential equations with mixed derivatives". Thesis, University of Macau, 2017. http://umaclib3.umac.mo/record=b3691348.
Texto completoTain, Cyril. "Modelling of type II superconductors : implementation with FreeFEM". Electronic Thesis or Diss., Normandie, 2023. http://www.theses.fr/2023NORMIR40.
Texto completoIn this thesis we present four models for type II superconductors: the London model, the time dependent Ginzburg-Landau (TDGL) model, the steady state Ginzburg-Landau model and an Abelian-Higgs model. For the London model a problem with cylindrical symmetry was considered. A hydrodynamic formulation of the problem was established through the introduction of a stream function. Well-posedness of the problem was proved. The external magnetic field was computed for 2D and 3D domains. In 3D a boundary element method was implemented using a recent feature of FreeFem. For the TDGL model two codes based on two variational formulations were proposed and tested on classical benchmarks of the literature in 2D and 3D. In the steady state GL model a Sobolev gradient technique was used to find the equilibrium state. The results were compared with the ones given by the TDGL model. In the Abelian-Higgs model a 1D finite differences code written in Fortran was developed and tested with the construction of a manufactured system. The model was used to retrieve some of the properties of magnetization of superconductors
ROSSI, ELENA. "Balance Laws: Non Local Mixed Systems and IBVPs". Doctoral thesis, Università degli Studi di Milano-Bicocca, 2016. http://hdl.handle.net/10281/103090.
Texto completoCasner, Bill. "A Mixed Method Study on Schema-Based Instruction, Mathematical Problem Solving Skills, and Students with an Educational Disability". Thesis, Lindenwood University, 2016. http://pqdtopen.proquest.com/#viewpdf?dispub=10244398.
Texto completoThe purpose of this study was to determine the student outcomes of implementing schema-based instruction on students in grades 3-8 identified with an educational disability and ascertain how students’ developed mathematical problem solving skills. After special education teachers in a metropolitan school district in the Midwest administered a pre-assessment, the researcher used the results to select 21 students with an educational disability to participate in the mixed-methods study. Special education teachers implemented Asha K. Jitendra’s (2007) educational program titled, Solving Math Word Problems: Teaching Students with Learning Disabilities Using Schema-Based Instruction, during the 2013-2014 school year and taught participants using these techniques. The researcher measured student achievement by using both a pre and post-assessment and M-CAP benchmark scores on mathematical problem solving. In addition, the researcher gathered perceptions of schema-based instruction via surveys and interviews with special education teachers, general education teachers, and student participants. The analysis of quantitative data from the pre and post-assessments of students participating in the schema-based program as well as the analysis of qualitative data from student participant surveys supported a positive outcome on the use of schema-based instruction with students with an educational disability; the findings of this study reinforced the then-current literature. However, the student participants' M-CAP assessment data did not demonstrate the same amount of growth as the assessment data from the schema-based program. In addition, the analysis of survey and interview data from the two teacher groups also displayed discrepancies between special education teachers’ and general education teachers’ overall perceptions of the schema-based instructional program. Despite this, the preponderance of evidence demonstrated most students who participated in the study did learn as a result of the schema-based instruction and developed mathematical problem-solving skills. Therefore, the findings of this study corroborated the then-current literature and supported the continual use of the researched program; Solving Math Word Problems: Teaching Students with Learning Disabilities Using Schema-Based Instruction, by Jitendra (2007). The researcher concluded this program a valid research-based intervention to increase mathematical problem solving skills for students with an educational disability.
Celebi, Emre. "MODELS OF EFFICIENT CONSUMER PRICING SCHEMES IN ELECTRICITY MARKETS". Thesis, University of Waterloo, 2005. http://hdl.handle.net/10012/811.
Texto completoHeuer, Christof. "High-order compact finite difference schemes for parabolic partial differential equations with mixed derivative terms and applications in computational finance". Thesis, University of Sussex, 2014. http://sro.sussex.ac.uk/id/eprint/49800/.
Texto completoAl-Shawabkeh, Rami. "The role of sustainable urban design principles in delivering high density mixed use schemes in Jordan : using Amman as a case study". Thesis, University of Brighton, 2015. https://research.brighton.ac.uk/en/studentTheses/35e734bb-741a-4b0d-8a5c-ea72231d19e3.
Texto completoLi, Ru. "Numerical simulations of natural or mixed convection in vertical channels : comparisons of level-set numerical schemes for the modeling of immiscible incompressible fluid flows". Phd thesis, Université Paris-Est, 2012. http://tel.archives-ouvertes.fr/tel-00806510.
Texto completoRue, Robert A. ""Mixed Taste," Cosmopolitanism, and Intertextuality in Georg Philipp Telemann's Opera Orpheus". Bowling Green State University / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1483456936606681.
Texto completoAggett, Jonathan Edward. "Financial Analysis of Restoring Sustainable Forests on Appalachian Mined Lands for Wood Products, Renewable Energy, Carbon Sequestration, and Other Ecosystem Services". Thesis, Virginia Tech, 2003. http://hdl.handle.net/10919/36096.
Texto completoMixed hardwood LEVs ranged from -$2416.71/ha (low prices) to $3955.72/ha (high prices). White pine LEVs ranged from -$2330.43/ha (low prices) to $3746.65/ha (high prices). A greater percentage of white pine scenarios yielded economically feasible land-use conversions than did the mixed hardwood scenarios, and it seems that a conversion to white pine forests would, for the most part, be the more appealing option. It seems that, for both mixed hardwoods and white pine, it would be in the best interests of the landowner to invest in the highest quality sites first. For a conversion to mixed hardwood forests, a low intensity level of site preparation seems economically optimal for most scenarios. For a conversion to white pine forests, a medium intensity level of site preparation seems economically optimal for most scenarios.
Mixed hardwoods lump sum payments, made at the time of planting, ranged from $0/ha to $2416.71/ha (low prices). White pine lump sum payments, made at the time of planting, ranged from $0/ha to $2330.53/ha (low prices). Mixed hardwoods benefits based on an increase in revenue at harvest, ranged from $0/ha to $784449.52/ha (low prices). White pine benefits based on an increase in revenue at harvest ranged from $0/ha to $7011.48/ha (high prices). Annual mixed hardwood benefits, based on total stand carbon volume present at the end of a given year, ranged from $0/ton of carbon to $5.26/ton carbon (low prices). White pine benefits based on carbon volume ranged from $0/ton of carbon to $18.61/ton of carbon (high prices). It appears that, for white pine scenarios, there is not much difference between incentive values for lump sum payments at planting, revenue incentives at harvest, and total carbon payments over a rotation. For mixed hardwoods, however, it appears that the carbon payment incentive is by far the cheapest option of encouraging landowners to convert land.
Master of Science
Souza, Grazione de. "Modelagem computacional de escoamentos com duas e três fases em reservatórios petrolíferos heterogêneos". Universidade do Estado do Rio de Janeiro, 2008. http://www.bdtd.uerj.br/tde_busca/arquivo.php?codArquivo=711.
Texto completoConsidera-se neste trabalho um modelo matemático para escoamentos com duas e três fases em reservatórios petrolíferos e a modelagem computacional do sistema de equações governantes para a sua solução numérica. Os fluidos são imiscíveis e incompressíveis e as heterogeneidades da rocha reservatório são modeladas estocasticamente. Além disso, é modelado o fenômeno de histerese para a fase óleo via funções de permeabilidades relativas. No caso de escoamentos trifásicos água-óleo-gás a escolha de expressões gerais para as funções de permeabilidades relativas pode levar à perda de hiperbolicidade estrita e, desta maneira, à existência de uma região elíptica ou de pontos umbílicos para o sistema não linear de leis de conservação hiperbólicas que descreve o transporte convectivo das fases fluidas. Como conseqüência, a perda de hiperbolicidade estrita pode levar à existência de choques não clássicos (também chamados de choques transicionais ou choques subcompressivos) nas soluções de escoamentos trifásicos, de difícil simulação numérica. Indica-se um método numérico com passo de tempo fracionário, baseado em uma técnica de decomposição de operadores, para a solução numérica do sistema governante de equações diferenciais parciais que modela o escoamento bifásico água-óleo imiscível em reservatórios de petróleo heterogêneos. Um simulador numérico bifásico água-óleo eficiente desenvolvido pelo grupo de pesquisa no qual o autor está inserido foi modificado com sucesso para incorporar a histerese sob as hipóteses consideradas. Os resultados numéricos obtidos para este caso indicam fortes evidências que o método proposto pode ser estendido para o caso trifásico água-óleo-gás. A técnica de decomposição de operadores em dois níveis permite o uso de passos de tempo distintos para os quatro problemas definidos pelo procedimento de decomposição: convecção, difusão, pressão-velocidade e relaxação para histerese. O problema de transporte convectivo (hiperbólico) das fases fluidas é aproximado por um esquema central de diferenças finitas explícito, conservativo, não oscilatório e de segunda ordem. Este esquema é combinado com elementos finitos mistos, localmente conservativos, para a aproximação dos problemas de transporte difusivo (parabólico) e de pressão-velocidade (elíptico). O operador temporal associado ao problema parabólico de difusão é resolvido fazendo-se uso de uma estratégia implícita de solução (Backward Euler). Uma equação diferencial ordinária é resolvida (analiticamente) para a relaxação relacionada à histerese. Resultados numéricos para o problema bifásico água-óleo em uma dimensão espacial em concordância com resultados semi-analíticos disponíveis na literatura foram reproduzidos e novos resultados em meios heterogêneos, em duas dimensões espaciais, são apresentados e a extensão desta técnica para o caso de problemas trifásicos água-óleo-gás é proposta.
We consider in this work a mathematical model for two- and three-phase flow problems in petroleum reservoirs and the computational modeling of the governing equations for its numerical solution. We consider two- (water-oil) and three-phase (water-gas-oil) incompressible, immiscible flow problems and the reservoir rock is considered to be heterogeneous. In our model, we also take into account the hysteresis effects in the oil relative permeability functions. In the case of three-phase flow, the choice of general expressions for the relative permeability functions may lead to the loss of strict hyperbolicity and, therefore, to the existence of an elliptic region or umbilic points for the system of nonlinear hyperbolic conservation laws describing the convective transport of the fluid phases. As a consequence, the loss of hyperbolicity may lead to the existence of nonclassical shocks (also called transitional shocks or undercompressive shocks) in three-phase flow solutions. We present a new, accurate fractional time-step method based on an operator splitting technique for the numerical solution of a system of partial differential equations modeling two-phase, immiscible water-oil flow problems in heterogeneous petroleum reservoirs. An efficient two-phase water-oil numerical simulator developed by our research group was sucessfuly extended to take into account hysteresis effects under the hypotesis previously annouced. The numerical results obtained by the procedure proposed indicate numerical evidence the method at hand can be extended for the case of related three-phase water-gas-oil flow problems. A two-level operator splitting technique allows for the use of distinct time steps for the four problems defined by the splitting procedure: convection, diffusion, pressure-velocity and relaxation for hysteresis. The convective transport (hyperbolic) of the fluid phases is approximated by a high resolution, nonoscillatory, second-order, conservative central difference scheme in the convection step. This scheme is combined with locally conservative mixed finite elements for the numerical solution of the diffusive transport (parabolic) and the pressure-velocity (elliptic) problems. The time discretization of the parabolic problem is performed by means of the implicit Backward Euler method. An ordinary diferential equation is solved (analytically) for the relaxation related to hysteresis. Two-phase water-oil numerical results in one space dimensional, in which are in a very good agreement with semi-analitycal results available in the literature, were computationaly reproduced and new numerical results in two dimensional heterogeneous media are also presented and the extension of this technique to the case of three-phase water-oil-gas flows problems is proposed.
Mint, brahim Maimouna. "Méthodes d'éléments finis pour le problème de changement de phase en milieux composites". Thesis, Bordeaux, 2016. http://www.theses.fr/2016BORD0157/document.
Texto completoIn this thesis we aim to develop a numerical tool that allow to solve the unsteady heatconduction problem in a composite media with a graphite foam matrix infiltrated witha phase change material such as salt, in the framework of latent heat thermal energystorage.In chapter 1, we start by explaining the model that we are studying which is separated in three sub-parts : a heat conduction problem in the foam, a phase change problem in the pores of the foam which are filled with salt and a contact resistance condition at the interface between both materials which results in a jump in the temperature field.In chapter 2, we study the steady heat conduction problem in a composite media withcontact resistance. This allow to focus on the main difficulty here which is the treatment of the thermal contact resistance at the interface between the carbon foam and the salt. Two Finite element methods are proposed in order to solve this problem : a finite element method based on Lagrange P1 and a hybrid dual finite element method using the lowest order Raviart-Thomas elements for the heat flux and P0 for the temperature. The numerical analysis of both methods is conducted and numerical examples are given to assert the analytic results. The work presented in this chapter has been published in the Journal of Scientific Computing [10].The phase change materials that we study here are mainly pure materials and as a consequence the change in phase occurs at a single point, the melting temperature. This introduces a jump in the liquid fraction and consequently in the enthalpy. This discontinuity represents an additional numerical difficulty that we propose to overcome by introducing a smoothing interval around the melting temperature. This is explained in chapter 3 where an analytical and numerical study shows that the error on the temperature behaves like " outside of the mushy zone, where _ is the width of the smoothing interval. However, inside the error behaves like p " and we prove that this estimation is optimal due to the energy trapped in the mushy zone. This chapter has been published in Communications in Mathematical Sciences [58].The next step is to determine a suitable time discretization scheme that allow to handle the non-linearity introduced by the phase change. For this purpose we present in chapter 4 four of the most used numerical schemes to solve the non-linear phase change problem : the update source method, the enthalpy linearization method, the apparent heat capacity method and the Chernoff method. Various numerical tests are conducted in order to test and compare these methods for various types of problems. Results show that the enthalpy linearization is the most accurate at each time step while the apparent heat capacity gives better results after a given time. This indicates that if we are interestedin the transitory states the first scheme is the best choice. However, if we are interested in the asymptotic thermal behavior of the material the second scheme is better. Results also show that the Chernoff scheme is the fastest in term of calculation time and gives comparable results to the one given by the first two methods.Finally, in chapter 5 we use the Chernoff method combined with the hybrid-dual finiteelement method with P0 and the lowest order Raviart-Thomas elements to solve thenon-linear heat conduction problem in a realistic composite media with a phase change material. Numerical simulations are realised using 2D-cuts of X-ray images of two real graphite matrix foams infiltrated with a salt. The aim of these simulations is to determine if the studied composite materials could be assimilated to an equivalent homogeneous phase change material with equivalent thermo-physical properties. For all simulationsconducted in this work we used the free finite element software FreeFem++ [41]
Abreu, Eduardo Cardoso de. "Modelagem e simulação computacional de escoamentos trifásicos em reservatórios de petróleo heterogêneos". Universidade do Estado do Rio de Janeiro, 2007. http://www.bdtd.uerj.br/tde_busca/arquivo.php?codArquivo=765.
Texto completoNeste trabalho é apresentado um novo método acurado com passo de tempo fracionário, baseado em uma técnica de decomposição de operadores, para a solução numérica de um sistema governante de equações diferenciais parciais que modela escoamento trifásico água-gás-óleo imiscível em reservatórios de petróleo heterogêneos no qual os efeitos de compressibilidade do gás não foram levados em conta. A técnica de decomposição de operadores em dois níveis permite o uso de passos de tempo distintos para os três problemas definidos pelo procedimento de decomposição: convecção, difusão e pressão-velocidade. Um sistema hiperbólico de leis de conservação que modela o transporte convectivo das fases fluidas é aproximado por um esquema central de diferenças finitas explícito, conservativo, não oscilatório e de segunda ordem. Este esquema é combinado com elementos finitos mistos, localmente conservativos, para a aproximação numérica dos sistemas de equações parabólico e elíptico associados aos problemas de transporte difusivo e de pressão-velocidade, respectivamente. O operador temporal associado ao sistema parabólico é resolvido fazendo-se uso de uma estratégia implícita de solução (Backward Euler). O modelo matemático para escoamento trifásico considerado neste trabalho leva em conta as forças de capilaridade e expressões gerais para as funções de permeabilidade relativa, campos variáveis de porosidade e de permeabilidade e os efeitos da gravidade. A escolha de expressões gerais para as funções de permeabilidade relativa pode levar à perda de hiperbolicidade escrita e, desta maneira, à existência de uma região elíptica ou de pontos umbílicos para o sistema não linear de leis de conservação hiperbólicas que descreve o transporte convectivo das fases fluidas. Como consequência, a perda de hiperbolicidade pode levar à existência de choques não clássicos (também chamados de choques transicionais ou choques subcompressivos) nas soluções de escoamentos trifásicos. O novo procedimento numérico foi usado para investigar a existência e a estabilidade de choques não clássicos, com respeito ao fenômeno de fingering viscoso, em problemas de escoamentos trifásicos bidimensionais em reservatórios heterogêneos, estendendo deste modo resultados disponíveis na literatura para problemas de escoamentos trifásicos unidimensionais. Experimentos numéricos, incluindo o estudo de estratégias de injeção alternada de água e gás (Water-Alternating-Gas (WAG)), indicam que o novo procedimento numérico proposto conduz com eficiência computacional a resultados numéricos com precisão. Perspectivas para trabalhos de pesquisa futuros são também discutidas, tomando como base os desenvolvimentos reportados nesta tese.
We present a new, accurate fractional time-step method based on an operator splitting technique for the numerical solution of a system of partial differential equations modeling three-phase immiscible water-gas-oil flow problems in heterogeneous petroleum reservoirs in which the compressibility effects of the gas was not take into account. A two-level operator splitting technique allows for the use of distinct time steps for the three problems defined by the splitting procedure: convection, diffusion and pressure-velocity. A system of hyperbolic conservation laws modelling the convective transport of the fluid phases is approximated by a high resolution, nonoscillatory, second-order, conservative central difference scheme in the convection step. This scheme is combined with locally conservative mixed finite elements for the numerical solution of the parabolic and elliptic problems associated with the diffusive transport of fluid phases and the pressure-velocity problem, respectively. The time discretization of the parabolic problem is performed by means of the implicit backward Euler method. The mathematical model for the three-phase flow considered in this work takes into account capillary forces and general expressions for the relative permeability functions, variable porosity and permeability fields, and the effect of gravity. The choice of general expressions for the relative permeability functions may lead to the loss of strict hyperbolicity and, therefore, to the existence of an elliptic region of umbilic points for the systems of nonlinear hyperbolic conservation laws describing the convective transport of the fluid phases. As a consequence, the loss of hyperbolicity may lead to the existence of nonclassical shocks (also called transitional shocks or undercompressive shocks) in three-phase flow solutions. The numerical procedure was used in an investigation of the existence and stability of nonclassical shocks with respect to viscous fingering in heterogeneous two-dimensional flows, thereby extending previous results for one-dimensional three-phase flow available in the literature. Numerical experiments, including the study of Water-Alternating-Gas (WAG) injection strategies, indicate that the proposed new numerical procedure leads to computational efficiency and accurate numerical results. Directions for further research are also discussed, based on the developments reported in this thesis.
Hsu, Cheng-Tien y 許政天. "A Global Optimization Scheme for Mixed-Integer Nonlinear Programming Problems". Thesis, 2005. http://ndltd.ncl.edu.tw/handle/23216204565902734184.
Texto completo逢甲大學
化學工程學所
93
This thesis aims at the development of a global optimization algorithm for the solution of mixed-integer nonlinear programming (MINLP) problems. A novel two-stage global optimization scheme is proposed. In the first stage, the modified Simulated Annealing (SA) algorithm is used to allocate the exact values of the discrete variables, while in the second stage the global optimal solution is obtained through making use of the information theory, a chaotic algorithm and a feasible point strategy. The applicability and effectiveness of the proposed global optimization scheme have been tested with some typical MINLP problems and extensive comparisons with existing SA and/or information theory-based algorithms have also performed in this work. Simulation results reveal that, due to the advantages of the chaotic algorithm and the two-stage solution approach, the proposed global optimization scheme is more efficient and outperforms the conventional SA and/or information theory-based algorithms. To extend the proposed global optimization scheme to the solution of the dynamic MINLP problems, we introduce the orthogonal collocation strategy for converting the original dynamic problem into a conventional MINLP problem. With this conversion, each of the dynamical constraint is reformulated into a set of equivalent discrete constraint forms with decision variables being at the pre-specified collocations points. This effort leads the proposed two-stage global optimization scheme directly applicable to the solution of dynamic MINLP problem and makes the solution procedure quite easy. For demonstration, we applied the solution scheme to solve several optimal control problems of dynamic chemical processes having simultaneously the continuous and discrete variables. Extensive simulation results corroborate again the effectiveness and advantage of the proposed global optimization schemes for the solution of MINLP problems.
ZHAN, ZHI-JANG y 詹志堅. "NUMERICAL INVESTIGATION OF SUPERSONIC MIXED-COMPRESSIONINLET USING A ROBUST UPWIND SCHEME". Thesis, 1990. http://ndltd.ncl.edu.tw/handle/72683206588831123740.
Texto completo國立成功大學
航空太空工程研究所
79
The problem of a typical supersonic mixed compression inlet that is characterized by multiple oblique shocks reflected in the supersonic diffusser and a terminating normal shock standing in the subsonic diffuser downstream of the throat is difficult to study. The complexities in this knid of intake system of a high-speed vehicle are numerically investigated. The interaction between shocks and the boundary layer plays an important role in the development of the boundary layer which in turn influences the performance of the inlet. The repid increase in the boundary layer thickness due to a large adverse pressure gradient across the shocks may cause flow separation, which can be eliminated by a careful design of the inlet contour and the incorporation of a bleed system. For the inlet studied here, the static pressure ratio through the inlet passage is as high as 31 for a designed flight Mach number 3.0. An improved scheme based on the second-order implicit upwind scheme of Coakley''s is presented. The scheme is a finite volume form, solving the Navier-Stokes equations. Several test cases are carried out to show the accuracy and efficiency of the present method. Calculations of an inviscid, one-dimensional, transonic nozzle flow and of a two-dimensional transoic channel flow show better shock-capturing capability of the scheme than a conventional central differencing scheme, or a flux vector splitting upwind scheme, and are comparable to the TVD scheme. Further verifications of the scheme both on the static pressure distribution and the skin friction distribution along the wall in the shock/laminar flat plate boundary layer interaction problem reveal that the present scheme is accurate and stable. The flowfields of an oblique shock impinging on a convex surface for different types of flow (i.e.,laminar, transitional, and trubulent) and different bleed amounts and locations are investigated for a better understanding of the effects of bleeding for boundary layer control. The objective of simulating a realistic mixed-compression supersonic inlet is finally accomplished. Problems encountered in the simulations, such as inlet unstart and overspeed analysis, are preseted and discussed in detail. The detailed flowfields, surface pressure distributions, the effect f bleed, simulation of a vortex generator (by enhancing a large eddy viscosity can prevent the flow reversal at engine face) and inlet performace parameters such as the total pressure recovery and the flow distortion are presented. The predictions are good in comparing the results with experimental data. It is believed and recommended that the present method, due to its accuracy and robustness, can be used as a good tool for the design of a supersonic intake system. 對於一具有多重斜震波反射於超音速擴散器及正震波形成於喉部區後次音速擴散器內 的超音速進氣道流場的分析是一件困難的工作。本文利用數值方法,藉以研究此類進 氣道系統的複雜流場。由於震波與邊界層之間的交互作用對邊界層的成長構成主要的 影響因素,因此,也進而影響到進氣道的性能。當邊界層承受由震波所引起之較大的 反向壓力梯度時,邊界層極容易流離物體表面,而此種現象可以以改進的內部外形設 計及有效利用吸氣裝置予以消除。針對本文所計算的設計點馬赫數為3.0 的進氣道而 言,出口與入口的靜壓比可以高達31.5,因此可見送向壓力梯度的重要性。 本文根據Clakley 所發展的二階準確隱式上游數值法,針對其缺點提出改良的方法, 並採用有限體積法之技巧以解可壓縮的Navier-Stokes 方程式。為了顯示本法的效率 及其準確性,測試相關的問題。對於非黏性一維及二維穿音速管流的問題,展現出本 法對於解析震波之能力,優於傳統之中央差分法及通向量分叉上游法,並且可以與先 進之TVD 法比擬。進一步的黏性流模擬於震波與平板層流邊界層交互作用之問題,更 顯現本法之準確性及穩定性。 最後本文完成了模擬一實際混合壓縮進氣道的流場及其分析。詳細的流場分析,壓力 在壁表面的分佈,吸流對於控制邊界層及正震波之穩定性的影響,渦流產生器的數學 模型模擬以及各種進氣道性能的參數指標,如全壓回復及流體扭曲都有詳盡的研究。 結果與實驗值所量測比較都相當吻合。我們相信並推薦本法,由於它本身的準確性及 穩定性,實可作為研究超音速進氣道系統之一有效分析工具。
Hong, Jing-neng y 洪敬能. "A Novel PWM/PAM Mixed Laser Modulation Scheme for Laser Scanning Projection System". Thesis, 2010. http://ndltd.ncl.edu.tw/handle/89628896222360097524.
Texto completo國立臺灣科技大學
光電工程研究所
98
Owing to the advancement of projection technology, the micro-projector is becoming more popular. Now, the main technology applied to projection display areDigital Light Processing(DLP), Liquid Crystal on Silicon(LCoS), and MEMS Mirror Scanning. The MEMS Mirror Scanning technology gets some advantages over others, such as lower energy consumption, more compact volume, and lower cost. The previous laser modulation technology applied to MEMS Mirror Scanning is mainly amplitude modulation(AM/PAM). This modulation type will cause the variation of color and brightness because the laser output power depends on the environment temperature. Our thesis proposes an novel method of laser modulation for the purpose of improving the previous defects and it can also enhancement the uniformity of display. We try to design a new laser driver circuits and builds up the digital video pattern conversion system. At last, we use this experimental platform to verify the innovative theory of laser modulation and prove that the innovative technology is better than amplitude modulation(AM/PAM) while environment temperature changing.
Alzahrani, Hasnaa H. "Mixed, Nonsplit, Extended Stability, Stiff Integration of Reaction Diffusion Equations". Thesis, 2016. http://hdl.handle.net/10754/617606.
Texto completoHsieh, Chih-Chiang y 謝智強. "Design of A Mixed Mode Code Acquisition Scheme for Direct-Sequence Spread Spectrum CDMA Systems". Thesis, 2001. http://ndltd.ncl.edu.tw/handle/57978520366371765475.
Texto completo國立臺灣科技大學
電機工程系
89
Matched filters are widely used by receiver design of a direct-sequence spread spectrum (DS-SS) system to achieve despreader of pseudo noise (PN) code. Among various types of Matched filter, serial-parallel architecture yields better trade off in between acquisition speed and circuit complexity. The main purpose of this thesis is to design a fast PN code acquisition detector to rapidly achieve initial synchronization between locally generated PN code and received PN code in a DS-SS system. There are two methods commonly employed in serial search technique: single dwell search and double dwell search. The double dwell search method is superior to single dwell search method in acquisition performance when input SNR is relatively good. While single dwell search method outperforms double dwell search method in acquisition when input SNR is poor. Since input SNR is closely related to the number of users accessing or noise interference the DS-SS system, and it is always pursued fast acquisition in a DS-SS system, it is therefore desired to have a code synchronizer that can achieve rapid code acquisition in both peak and non-peak hours. To this end, the other object of this thesis proposes a mixed mode code synchronizer employing both single and double dwell search methods in which single dwell search is adopted when input SNR is poor while double dwell search is applied when input SNR is relatively good. This thesis also presents the SNR estimation circuit to determine the timing to employ single dwell search or double dwell search.
Chang, Chih-Chien y 張志健. "A Mixed-Signal Calibration Scheme for the Fully Differential Successive Approximation Analog-to-Digital Converter". Thesis, 2011. http://ndltd.ncl.edu.tw/handle/36862163230714711690.
Texto completo國立交通大學
電控工程研究所
99
It is the mismatched capacitors due to process variation that limit the resolution of a conventional capacitive SAR ADC. To address this issue, this thesis proposes a mixed-signal calibration scheme for the fully differential SAR ADC. The proposed calibration scheme first estimates the ratio errors of the capacitors under calibration in the binary weighted capacitor array. Then, the errors will be digitized and stored. When the SAR ADC operates in the normal conversion, the calibration scheme will compensate the errors caused by the DAC in an analog way. The calibration scheme proposed in this thesis is able to calibrate the ratio errors of the capacitors, no matter the ratio error is positive or negative. With the proposed calibration scheme, the effective number of bits of the SAR ADC can be enhanced. Simulation results show that the INL values are improved from -11~+11 LSB to -0.9~+0.9 LSB after calibration, and the SNDR and ENOB values are enhanced from 51.7dB and 8.3bits to 71.6dB and 11.6bits after calibration. The results show that the ADC’s performance can be significantly improved with the proposed calibration scheme. We implemented a 12-bit 1.8V SAR ADC with the proposed calibration scheme in TSMC 0.18µm 1P6M CMOS process. Measurement results show that the SAR ADC achieves SNDR of 53.3dB and ENOB of 8.6 bits at 10 MS/s before calibration. The ADC consumes 5.94mW at 1.8-V. The measurement results show this calibration method can be improved. The main issue is the mismatch between the main DAC and the sub DAC in the segmented structure. It is our future work to address this issue.
Zhang, Ming Hua y 張明化. "The coexistance analysis of CDMA and TDMA scheme with overlaid/underlaid mixed macrocell/microcell cellular structures". Thesis, 1996. http://ndltd.ncl.edu.tw/handle/92530178896708832622.
Texto completoJhong, Ren-Kai y 鍾仁凱. "Study on Mixed Supercritical and Subcritical Flows Using Explicit Finite Analytic Method and MacCormack Hybrid Scheme". Thesis, 2009. http://ndltd.ncl.edu.tw/handle/67690760628981645748.
Texto completo國立交通大學
土木工程系所
97
This study extends Hsu and Yeh’s (1996) one-dimensional explicit finite analytic model (EFA) for simulating supercritical and mixed supercritical and subcritical flows. The essence of the EFA is the adoption of the concept of method of characteristics to the momentum equation for solving the local analytic solution of the dependent variables (i.e., discharge and cross-section area of flow). To ensure stability of the scheme, Courant condition should be obeyed. The dependent variables at the upstream and downstream boundaries are obtained through the method of characteristics. For the interior boundary condition at mixed supercritical and subcritical flows, the locations of the occurrences of hydraulic jumps are determined according to the values of Froude numbers. And water depths for supercritical regime at downstream boundaries were calculated. This was done through the method of MacCormack scheme and method of characteristics, by utilizing the water surface elevations of the interior neighboring computational points. The mixed supercritical and subcritical flow fields in laboratory flumes and natural rivers will be simulated and evaluated by the proposed model.
簡勁舟. "Run-to-run control scheme for a mixed-run process with single tool and multiple products". Thesis, 2011. http://ndltd.ncl.edu.tw/handle/94620779000262420122.
Texto completo國立清華大學
統計學研究所
99
Exponentially weighted moving average (EWMA) controller has been widely used in semiconductor manufacturing processes. In the literatures, several papers addressed the efforts of long-term stability and short-term performance of EWMA control scheme. However, all the existing models are only valid when focusing on single-product and single-tool production style. In practical applications, multiple-product and multiple-tool production style is common for the practical implementation of run to run (R2R) control scheme. Recently, product-based approach and tool-based approach have been proposed to handle this mixed-run production problem. Although these control schemes will eventually bring the process output to the desired targets; they may suffer from a larger rework rate (RR) due to larger process variations. To overcome this difficulty, we propose a modified single EWMA controller to tackle this problem. We first address the stability conditions of the proposed controller. The result demonstrates that the stability conditions of the proposed controller will be held under some specific assumptions. Furthermore, we also use simulation study to investigate the performance of the proposed controller via total mean square error (TMSE) and RR criterion. The results demonstrate proposed controller outperforms existing models.
Kang, Jun Won 1975. "A mixed unsplit-field PML-based scheme for full waveform inversion in the time-domain using scalar waves". Thesis, 2010. http://hdl.handle.net/2152/ETD-UT-2010-05-1263.
Texto completotext
Su, Jiun-Jang y 蘇俊彰. "Design and Performance Analysis of A Mixed Mode Code Acquisition Scheme for Direct-Sequence Spread Spectrum CDMA Systems". Thesis, 2001. http://ndltd.ncl.edu.tw/handle/04463634739109821463.
Texto completo國立臺灣科技大學
電機工程系
89
The purpose of this thesis is to design a fast PN code acquisition detector to rapidly achieve initial synchronization between locally generated PN code and the received PN code in a direct-sequence spread-spectrum (DS-SS) code division multiple access (CDMA) system. There are two methods commonly employed in serial search technique: single dwell and multiple dwell (mostly double dwell). The double dwell search method is superior to single dwell search method in acquisition performance when input SNR is relatively good. While single dwell search method outperforms double dwell search method in acquisition when input SNR is poor. Since input SNR is closely related to the number of users accessing the CDMA system, and it is always pursued fast acquisition in a DS-SS CDMA system, it is therefore desired to have a code synchronizer that can achieve rapid code acquisition in both peak and non-peak hours. To this end, this research proposes a mixed mode code synchronizer employing both single and double dwell search methods in which single dwell search is adopted when input SNR is poor while double dwell search is applied when input SNR is relatively good. This thesis will analyze the acquisition performance of the proposed code acquisition scheme in terms of SNR, detection probability and false alarm rate.
Yan, Shiang-Kun y 顏翔崑. "Large Eddy Simulations of Turbulent Mixed Convection in a Vertical Plane Channel Using a New Fully-Conservative Scheme". Thesis, 2002. http://ndltd.ncl.edu.tw/handle/k3d46b.
Texto completo國立成功大學
航空太空工程學系碩博士班
90
A central difference (dissipation-free) scheme has to conserve kinetic energy to avoid numerical instability when a long-term time integration for incompressible flow such as large eddy simulation or direct numerical simulation is performed. A scheme is called fully conservative if it can simultaneously conserve mass, momentum, and kinetic energy in the discrete sense. A theoretical analysis is performed to extend the fully conservative schemes to non-uniform grid systems without sacrificing any conservative properties. The main step is to design a convective scheme which conserves momentum and kinetic energy simultaneously. An analysis is made for the second-order accurate scheme of Harlow and Welsh for staggered grid systems and it is found that the flux velocities need to be viewed as mass fluxes across control surfaces to conserve kinetic energy. To extend the analysis to higher order schemes, it is necessary to work in computational space. The contravariant-Cartensian velocity formulation for the convection term in computational space has the similar structure for the proposed fully conservative second-order scheme in physical space. Using the velocity formulation, the higher order convective schemes of Morinishi are extended to non-uniform staggered grid systems for the advective, divergence and skew-symmetric forms. The higher order schemes for scalar variables which conserve the square of the scalar variables are also derived. Several numerical tests are used to validate the conservative properties, accuracy and performance of the proposed higher order schemes. A series of LESs of turbulent heat transfer in channel flow to study the contributions of SGS motions and the influences of grid number on turbulent statistics. Large eddy simulations are performed to study fully developed turbulent mixed convection in a vertical plane channel, Re_b = 5600 and Pr = 0.71, with uniform heating or cooling from both walls. The main features of turbulent mixed convection are produced. For aiding flow, a transition Gr_q number, Gr_q = 1.40x10^8, exists. Before the transition number, the turbulence is generated mostly by the shear force driven by the pressure gradient. The turbulent statistics are similar in shape to those for forced convection while the magnitudes reduce slightly in the near-wall region for all turbulent statistics and the friction coefficient and the Nusselt number also decrease gradually. The buoyancy production term in the budget of turbulent kinetic energy remain small and negative over the whole channel. Around the transition Gr_q number, the regeneration process of near-wall structures are destroyed mostly. Second order statistics show the severest deterioration in the near-wall region and the turbulence generated by buoyancy becomes apparent on turbulent statistics away from the wall. The friction coefficient and the Nusselt number decline to 85% and 45%, respectively, of that at Gr_q=0. The point of the maximum mean velocity begins to shift away from the channel center and the Reynolds shear stress and streamwise turbulent heat flux change sign nearly at the location of the maximum mean velocity. The buoyancy production term changes sign, and thus the term becomes a main producing term while y is larger than the zero point. The similarity between u' and theta' begins to deteriorate. After the transition Gr_q number, turbulence generated by buoyancy gradually increases its influence on turbulent statistics. The magnitudes increase gradually in the near-wall region for all turbulent statistics, the friction coefficient and the Nusselt number with increasing Gr_q number. The dissimilarity between u' and theta' increases gradually and the thermal plumes become the main structures at highest simulated Gr_q. For opposing flow, the contributions of the buoyant force and Reynolds shear stress are in the opposite direction, and thus the turbulence intensity increases as the buoyant force increases. The turbulent statistics are similar in shape to those for forced convection while the magnitudes increase in the near-wall region for all turbulent statistics except for the mean streamwise velocity and the friction coefficient, and the Nusselt number also increases gradually with increasing Gr_q number. The near-wall streaky structures are similar to those of Gr_q = 0, but the dissimilarity between u' and theta' is observed at the highest simulated Gr_q.
Shih, Wun-Cai y 施文財. "Digital Signal Processing Scheme for Wearable Devices-Using Mixed Fixed-Point and IEEE-754 Floating-Point Digital Filter Implementations". Thesis, 2016. http://ndltd.ncl.edu.tw/handle/40791590197410585385.
Texto completo亞洲大學
光電與通訊學系碩士在職專班
104
This thesis presents the hybrid architecture of floating-point and fixed-point com-putations using normal-form transformation for finite-precision infinite impulse response (IIR) digital filter state-space implementations. The proposed method pro-vides for well compromise between operational speed and output performance. To obtain higher operational speed, the state equation of a digital filter is implemented by fixed-point format. In contrary, to reduce the distortion occurred from underflow effect, floating-point format is implemented in the output equation. The developed digital filter implementation method is suitable for the use in narrow band imple-mentations, such as the narrow stop band IIR digital filter for eliminating power line interferences, or an extremely low pass band filter to reject the baseline wander in a wearable mini-ECG. We have found that the underflow effect is associated with the bandwidth and the sampling frequency in digital filter implementations. Some nu-merical examples illustrate the effectiveness of our proposed approach.
Shobiye, Hezekiah Olayinka. "The determinants of insurance participation: a mixed-methods study exploring the benefits, challenges and expectations among healthcare providers in Lagos, Nigeria". Thesis, 2018. https://hdl.handle.net/2144/32684.
Texto completoGau, Chi-Yuan y 高啟元. "Impulse, Gaussian, and Mixed Noise Suppression Schemes for Digital Images". Thesis, 2001. http://ndltd.ncl.edu.tw/handle/22696020259766744626.
Texto completo國立交通大學
電機與控制工程系
89
The noise is commonly observed in many practical system, and the system’s output is greatly affected by the existence of the noise. Therefore, it is necessary and important to remove the noise. The thesis introduces several schemes for the image noise removal: the noise discussed here contains the impulse and Gaussian noise distribution, and both. First filters were designed to process some single noise type. Observe that the noise usually appears in mixed mode in a practical system. When the noise appears in mixed mode, the filters for single noise type mentioned above can not facilitate an effective filter action. Different from the design of filters above, we propose a method that can remove the noise mixed with impulse and Gaussian noise from an image. First, we detect the image pixel to check whether the image pixel is impulse noise contaminated or not. If the pixel is corrupted by the impulse noise, a new median filtering is applied to replace the noisy pixel, which will prevent to distract the original image pixel. Then the processed image is filtered by the use of the fuzzy rule-based filter to remove the remaining noise, whose noise contains Gaussian type mostly. The fuzzy rule-based filter’s output is a weighted-average sum. It is based on the three parameters: the gray level difference between pixels, the spatial distance and direction between pixels, and the variance in the local window. Using the LMS algorithm we can determine the membership function for the filter. From the simulation results, our proposal scheme has demonstrated the effectiveness and robustness, in comparison with other filters in image noise removal.
Dalmia, Kamal. "Built-in jitter test schemes for mixed-signal integrated circuits". Thesis, 1996. http://hdl.handle.net/2429/7771.
Texto completoKnight, Emma. "Improved iterative schemes for REML estimation of variance parameters in linear mixed models". 2008. http://hdl.handle.net/2440/49425.
Texto completoThesis (Ph.D.) - University of Adelaide, School of Agriculture, Food and Wine, 2008
Knight, Emma Jane. "Improved iterative schemes for REML estimation of variance parameters in linear mixed models". 2008. http://digital.library.adelaide.edu.au/dspace/handle/2440/49425.
Texto completo"Redefining Situation Schema Under Chronic Stress: A Mixed Methods Construct Validation of Positive Cognitive Shift". Doctoral diss., 2018. http://hdl.handle.net/2286/R.I.50113.
Texto completoDissertation/Thesis
Doctoral Dissertation Psychology 2018
Wu, Lingyi y 吳玲儀. "A simulation Study of Various Run-to-Run Control Schemes for a Mixed-Run Production System". Thesis, 2013. http://ndltd.ncl.edu.tw/handle/95057108326736547055.
Texto completo靜宜大學
財務與計算數學系
101
Exponentially weighted moving average (EWMA) is commonly used in Run-to-run (R2R) control of the semiconductor manufacturing process. The EWMA feedback controller is a popular model-based controller which primarily uses data from past process run to adjust the input recipe for the next run. In the literatures, several papers addressed the efforts of long-term stability and short-term performance of EWMA control scheme. However, in practical applications, multiple-tool and multiple- product production style is common for the practical implementation of R2R control scheme. A single EWMAcontroller can not be directly used to monitor the production process. Thus, for a such mixing production style, product-based controller, tool-based controller, MTB controller, modified sing EWMA controller and DREWMA controller have been proposed. Therefore, in this paper, we adopt the Distrubance retuned EWMA (DREWMA) controller to discuss the improvement of total means square error (TMSE), to explore different combinations of process disturbances under various controllers and its relative efficiency and to make comparison and analysis of the merits and drawbacks so as to efficiently use the existing controller to significantly reduce TMSE.
Lu, Ting-Yuan y 陸庭元. "The Coexistance Analysis of FH/DS Schemes in Overlaid/Underlaid Architectures with Mixed Macrocell/Microcell Cellular Structure". Thesis, 1996. http://ndltd.ncl.edu.tw/handle/86926369931472780966.
Texto completoLiaw, Cai-Pin y 廖采頻. "The Null-Field Methods and Conservative schemes of Laplace’s Equation for Dirichlet and Mixed Types Boundary Conditions". Thesis, 2011. http://ndltd.ncl.edu.tw/handle/13133549896617901995.
Texto completo國立中山大學
應用數學系研究所
99
In this thesis, the boundary errors are defined for the NFM to explore the convergence rates, and the condition numbers are derived for simple cases to explore numerical stability. The optimal convergence (or exponential) rates are discovered numerically. This thesis is also devoted to seek better choice of locations for the field nodes of the FS expansions. It is found that the location of field nodes Q does not affect much on convergence rates, but do have influence on stability. Let δ denote the distance of Q to ∂S. The larger δ is chosen, the worse the instability of the NFM occurs. As a result, δ = 0 (i.e., Q ∈ ∂S) is the best for stability. However, when δ > 0, the errors are slightly smaller. Therefore, small δ is a favorable choice for both high accuracy and good stability. This new discovery enhances the proper application of the NFM. However, even for the Dirichlet problem of Laplace’s equation, when the logarithmic capacity (transfinite diameter) C_Γ = 1, the solutions may not exist, or not unique if existing, to cause a singularity of the discrete algebraic equations. The problem with C_Γ = 1 in the BEM is called the degenerate scale problems. The original explicit algebraic equations do not satisfy the conservative law, and may fall into the degenerate scale problem discussed in Chen et al. [15, 14, 16], Christiansen [35] and Tomlinson [42]. An analysis is explored in this thesis for the degenerate scale problem of the NFM. In this thesis, the new conservative schemes are derived, where an equation between two unknown variables must satisfy, so that one of them is removed from the unknowns, to yield the conservative schemes. The conservative schemes always bypasses the degenerate scale problem; but it causes a severe instability. To restore the good stability, the overdetermined system and truncated singular value decomposition (TSVD) are proposed. Moreover, the overdetermined system is more advantageous due to simpler algorithms and the slightly better performance in error and stability. More importantly, such numerical techniques can also be used, to deal with the degenerate scale problems of the original NFM in [15, 14, 16]. For the boundary integral equation (BIE) of the first kind, the trigonometric functions are used in Arnold [3], and error analysis is made for infinite smooth solutions, to derive the exponential convergence rates. In Cheng’s Ph. Dissertation [18], for BIE of the first kind the source nodes are located outside of the solution domain, the linear combination of fundamental solutions are used, error analysis is made only for circular domains. So far it seems to exist no error analysis for the new NFM of Chen, which is one of the goal of this thesis. First, the solution of the NFM is equivalent to that of the Galerkin method involving the trapezoidal rule, and the renovated analysis can be found from the finite element theory. In this thesis, the error boundary are derived for the Dirichlet, the Neumann problems and its mixed types. For certain regularity of the solutions, the optimal convergence rates are derived under certain circumstances. Numerical experiments are carried out, to support the error made.