Дисертації з теми "Continuous casting Mathematical models"
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Bradbury, Philip. "A mathematical model for the twin roll casting process." Thesis, University of Oxford, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.296919.
Повний текст джерелаBouhouche, Salah. "Contribution to quality and process optimisation in continuous casting using mathematical modelling." Doctoral thesis, Technische Universitaet Bergakademie Freiberg Universitaetsbibliothek "Georgius Agricola", 2009. http://nbn-resolving.de/urn:nbn:de:swb:105-6900128.
Повний текст джерелаBouhouche, Salah. "Contribution to quality and process optimisation in continuous casting using mathematical modelling." Doctoral thesis, [S.l. : s.n.], 2002. http://deposit.ddb.de/cgi-bin/dokserv?idn=966041208.
Повний текст джерелаSpinelli, Jose Eduardo. "Simulação do lingotamento continuo de tiras finas de aços." [s.n.], 2000. http://repositorio.unicamp.br/jspui/handle/REPOSIP/264701.
Повний текст джерелаDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica
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Resumo: Entende-se por modelagem de processo, o desenvolvimento de uma representação quantitativa ou qualitativa dos fenômenos físicos associados ao processo. Neste trabalho são realizadas simulações do processo twin roll de lingotamento contínuo de tiras de aços, utilizando como referência tecnológica o equipamento piloto instalado nas dependências do Instituto de Pesquisas Tecnológicas do Estado de São Paulo. São construídos dois simuladores para o processo: um simulador da solidificação unidirecional, com molde refrigerado de aço e paredes laterais de material refratário, utilizando-se o aço inoxidável 304 como material de simulação; e variando-se as temperaturas de vazamento; e outro simulador a frio, com componentes feitos de acrílico, água como fluido de simulação e permanganato de potássio como corante. Um modelo matemático previamente desenvolvido é utilizado para confrontar perfis térmicos teóricos com perfis experimentais, para a determinação do coeficiente de transferência de calor metal/molde. O levantamento de valores de espaçamento dendrítico secundário é realizado nas amostras, além da observação simultânea das estruturas de solidificação, o que comprovou a eficiência do simulador em caracterizar o processo de solidificação do equipamento piloto. O uso do modelo frio permitiu a caracterização do posicionamento de barreira a 15 cm ou a 20 cm da lateral esquerda do distribuidor como a melhor configuração
Abstract: It can be understood by process modeling the development of a quantitative or qualitative representation of the physical phenomena associated to the process. In this work, simulations concerning the twin roll continuous caster of steels process at IPT (Instituto de Pesquisas Tecnológicas do Estado de São Paulo) are performed. Two simulators were developed: (i) a simulator of unidirectional solidification with cooled steel mold and refractory lateral walls, by using a stainless steel as the reference metal (AISI 304), and varying superheat temperatures; (ii) a physical model, with components made of acrylic, water as the simulation fluid and potassium permanganate as a pigment. A previously developed mathematical model has been used to determine the metal/mold heat transfer coefficient by a method that compares experimenta1ltheoretical temperature curves. Measurement of secondary dendrite arm spacings is performed by microestructural examination of the samples, confirming the simulator efficiency in characterizing the solidification process in the pilot equipment. The use of the physical model has permitted to attain the best configuration for the tundish, by positioning the dam 15 cm or 20 cm from the left side of tundish
Mestrado
Materiais e Processos de Fabricação
Mestre em Engenharia Mecânica
De, Wet Gideon Jacobus. "CFD modelling and mathematical optimisation of a continuous caster submerge entry nozzle." Pretoria : [s.n.], 2005. http://upetd.up.ac.za/thesis/available/etd-01312006-141026.
Повний текст джерелаDasci, Abdullah. "Discrete and continuous models for production-distribution systems." Thesis, McGill University, 2001. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=37625.
Повний текст джерелаThe models proposed in this thesis are based on two fundamentally different but equally central approaches. The first approach builds on traditionally popular integer programming formulation in facility location theory, in which two such models presented in this thesis. The first one assumes that there are a number of dedicated production technologies for each product whereas, the second one assumes that a set of flexible technologies is also present. Analytical properties of the models are described, which lead to the development of exact and heuristic solution procedures. Results of several sets of computational experiments are also reported. The second approach is based on continuous approximation (also known as continuum mechanics), which has not been used to its potential in the literature. The third model in this thesis is proposed for a system with single product. It is based on the use of continuous functions in representing spatial distribution of cost parameters and decision variables. In this model, the focus is to compute the service regions leaving the precise plant locations to a subsequent analysis. This model lends itself to closed form solutions and allows derivation of a number of insights on the impact of several cost factors on facility design decisions. Then, it is utilized in an analytical framework to analyze several plant focus decisions of firms in a multi-product environment. The closed form solution is used to analyze several product and market focus strategies, which have provided several insights into more sophisticated plant focus decisions and into the impact of different production technologies on these decisions.
Uribe, Guillermo. "On the relationship between continuous and discrete models for size-structured population dynamics." Diss., The University of Arizona, 1993. http://hdl.handle.net/10150/186197.
Повний текст джерелаParra, Rojas César. "Intrinsic fluctuations in discrete and continuous time models." Thesis, University of Manchester, 2017. https://www.research.manchester.ac.uk/portal/en/theses/intrinsic-fluctuations-in-discrete-and-continuous-time-models(d7006a2b-1496-44f2-8423-1f2fa72be1a5).html.
Повний текст джерелаLi, Chao. "Option pricing with generalized continuous time random walk models." Thesis, Queen Mary, University of London, 2016. http://qmro.qmul.ac.uk/xmlui/handle/123456789/23202.
Повний текст джерелаBouraoui, Faycal. "Development of a continuous, physically-based distributed parameter, nonpoint source model." Diss., This resource online, 1994. http://scholar.lib.vt.edu/theses/available/etd-10192006-115604/.
Повний текст джерелаKleinow, Torsten. "Testing continuous time models in financial markets." Doctoral thesis, [S.l. : s.n.], 2002. http://deposit.ddb.de/cgi-bin/dokserv?idn=965412091.
Повний текст джерелаShek, Cheuk-man Edmond, and 石焯文. "The continuous and discrete extended Korteweg-de Vries equations and their applications in hydrodynamics and lattice dynamics." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2006. http://hub.hku.hk/bib/B36925585.
Повний текст джерелаCasas, Villalba Isabel. "Statistical inference in continuous-time models with short-range and/or long-range dependence." University of Western Australia. School of Mathematics and Statistics, 2006. http://theses.library.uwa.edu.au/adt-WU2006.0133.
Повний текст джерелаSwallow, Ben. "Bayesian multi-species modelling of non-negative continuous ecological data with a discrete mass at zero." Thesis, University of St Andrews, 2015. http://hdl.handle.net/10023/9626.
Повний текст джерелаMousavizadeh, Mohammad Hassan. "Integration of a geographic information system and a continuous nonpoint source pollution model to evaluate the hydrologic response of an agricultural watershed." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape11/PQDD_0015/NQ44524.pdf.
Повний текст джерелаKholmatov, Shavkat. "On some positive effects of swirling flow for the continuous cast mould billets." Licentiate thesis, Stockholm : Division of Applied Process Metallurgy, School of Industrial Engineering and Management, Royal Institute of Technology, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4453.
Повний текст джерелаStrandberg, Per Erik. "Mathematical models of bacteria population growth in bioreactors: formulation, phase space pictures, optimisation and control." Thesis, Linköping University, Department of Mathematics, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-2337.
Повний текст джерелаThere are many types of bioreactors used for producing bacteria populations in commercial, medical and research applications.
This report presents a systematic discussion of some of the most important models corresponding to the well known reproduction kinetics such as the Michaelis-Menten kinetics, competitive substrate inhibition and competitive product inhibition. We propose a modification of a known model, analyze it in the same manner as known models and discuss the most popular types of bioreactors and ways of controlling them.
This work summarises much of the known results and may serve as an aid in attempts to design new models.
Lee, Jinpyo. "A method for distribution network design and models for option-contracting strategy with buyers' learning." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/29620.
Повний текст джерелаCommittee Chair: Kleywegt, Anton J.; Committee Member: Ayhan, Hayriye; Committee Member: Dai, Jim; Committee Member: Erera, Alan; Committee Member: Ward, Amy R. Part of the SMARTech Electronic Thesis and Dissertation Collection.
Wang, Ni. "Statistical Learning in Logistics and Manufacturing Systems." Diss., Georgia Institute of Technology, 2006. http://hdl.handle.net/1853/11457.
Повний текст джерелаNascimento, Renato Rosa do. "Controle não linear aplicado a processos de lingotamento contínuo de tiras." Universidade de São Paulo, 2002. http://www.teses.usp.br/teses/disponiveis/18/18133/tde-05062017-090446/.
Повний текст джерелаThe aim of this work is to explore the use of advanced control techniques in the metallurgical industry. A control strategy to regulate the molten steellevel of a strip-casting process is proposed. The process produces a solidified strip of constant thickness given by the roll gap under a constant roll separation force. Along with the molten steel level the rool separation force are the most criticaI process variables. The molten steel level may be controlled using the tundish output flow or the casting speed. However, the casting speed is usually used to control the roll force separation. In the control strategy proposed it is incorporated an intermediary tundish submerse into the pool between the rotating rolls to improve the strip thickness uniformity. The molten steel level is thus controlled by the intermediary tundish output flow. Conventional PI, feedback linearizing plus a fuzzy control term and a fuzzy controller in a cascade configuration are considered. Simulation results are presented considering the real system parameters of a plant installed at the Instituto de Pesquisa Tecnológica (IPT) de São Paulo, Divisão de Metalurgia (DIMET).
Mezzomo, Meire. "AVALIAÇÃO DA QUALIDADE DO PROCESSO DE LINGOTAMENTO CONTÍNUO NA PRESENÇA DE CORRELAÇÃO CRUZADA." Universidade Federal de Santa Maria, 2013. http://repositorio.ufsm.br/handle/1/8290.
Повний текст джерелаIn the current competitive market, a great part of companies has as the main goal the search for continuous improvement of their products and services. Therefore, the application of statistical methods has great relevance in the quality evaluation, helping in the understanding and monitoring of the processes. In such context, the present study concerns to the use of multivariate control charts in the evaluation of the productive processes in the presence of cross-correlation, which the objective is to verify the continuous casting process stability in the production of still billets by means of Hotelling's T2 multivariate control charts applied in the estimated residual mathematical linear models. Initially, the existence of data autocorrelation was verified, it is necessary the ARIMA modeling, because when it happens, it is necessary to determine the residues and apply multivariate control charts to the residues and not on the original variables. The existence of correlation showed to be meaningful among the variables, being one of the assumptions for the statistical application T2. When the T2 chart instability is verified, it was necessary to identify the variable or the set of variables of steel temperatures in the distributor and in the distributor weight, which are responsible for the instability. Later, the estimated residues were decomposed into principal components, and with the help of the correlation of the original variables and the principal components, the variables which most contributed to the formation of each component were identified. Therefore, it was possible to detect the variables which caused the system instability, once for the steel temperature in the distributor were the T4 and T5, followed by T6, T3, T7 and T2 and for the weight of the distributor, PD4, PD5, PD3, PD6 and PD2, respectively. This way, the estimated residues from the mathematical models, the use of multivariate chart control Hotelling's T2 and the decomposition into principal components which were able to represent the productive process. This methodology allowed the understanding of the behavior of the variables and helped the monitoring of this process, as well as, in the determination of the possible variables which caused the instability in the continuous casting process.
No atual mercado competitivo, grande parte das empresas tem como principal objetivo a busca da melhoria contínua dos seus produtos e serviços. Assim, a aplicação de métodos estatísticos apresenta grande relevância na avaliação da qualidade, auxiliando na compreensão e monitoramento de processos. Nesse contexto, o presente estudo aborda a utilização de gráficos de controle multivariados na avaliação do processo produtivo na presença de correlação cruzada, cujo objetivo é verificar a estabilidade do processo de lingotamento contínuo na fabricação de tarugos de aço por meio do gráfico de controle multivariado T2 de Hotelling aplicado nos resíduos estimados de modelos matemáticos lineares. Inicialmente, foi verificada a existência de autocorrelação nos dados, sendo necessária a utilização da modelagem ARIMA, pois quando isso ocorre, deve-se proceder à determinação dos resíduos e aplicar os gráficos de controle multivariados aos resíduos e não nas variáveis originais. A existência de correlação cruzada mostrou-se significativa entre as variáveis, sendo um dos pressupostos para a aplicação da estatística T2. Verificada a instabilidade no gráfico T2, buscaram-se identificar a variável ou conjunto de variáveis das temperaturas do aço no distribuidor e peso do distribuidor, responsáveis pela instabilidade. Posteriormente, os resíduos estimados foram decompostos em componentes principais, e com o auxílio da correlação entre as variáveis originais e as componentes principais, identificou-se as variáveis que mais contribuíram para a formação de cada componente. Assim, foi possível detectar as variáveis causadoras da instabilidade do sistema, sendo que para às temperaturas do aço no distribuidor foram às temperaturas T4 e T5, seguidas de T6, T3, T7 e T2 e para o peso do distribuidor, PD4, PD5, PD3, PD6 e PD2, respectivamente. Deste modo, os resíduos estimados oriundos dos modelos matemáticos, a aplicação dos gráficos de controle multivariados T2 de Hotelling e a decomposição em componentes principais foram capazes de representar o processo produtivo. Esta metodologia possibilitou a compreensão do comportamento das variáveis e auxiliou no monitoramento do processo, bem como, na determinação das possíveis variáveis causadoras da instabilidade no processo de lingotamento contínuo.
Zhu, Shousheng. "Modeling, identifiability analysis and parameter estimation of a spatial-transmission model of chikungunya in a spatially continuous domain." Thesis, Compiègne, 2017. http://www.theses.fr/2017COMP2341/document.
Повний текст джерелаIn different fields of research, modeling has become an effective tool for studying and predicting the possible evolution of a system, particularly in epidemiology. Due to the globalization and the genetic mutation of certain diseases or transmission vectors, several epidemics have appeared in regions not yet concerned in the last years. In this thesis, a model describing the transmission of the chikungunya epidemic to the human population is studied. As a novelty, this model incorporates the spatial mobility of humans. Indeed, it is an interesting factor that has influenced the re-emergence of several epidemic diseases. The displacement of mosquitoes is omitted since it is limited to a few meters. The complete model (ODEs-PDEs model) is then composed of a reaction-diffusion system (taken the form of semi-linear parabolic partial differential equations (PDEs)) coupled with ordinary differential equations (ODEs). We prove the existence, uniqueness, positivity and boundedness of a global solution of this model at first and then give some numerical simulations. In such a model, some parameters are not directly accessible from experiments and have to be estimated numerically. However, before searching for their values, it is essential to verify the identifiability of parameters in order to assess whether the set of unknown parameters can be uniquely determined from the data. This study will insure that numerical procedures can be successful. If the identifiability is not ensured, some supplementary data have to be added. In fact, a first identifiability study had been done for the ODEs model by considering that the number of eggs can be easily counted. However, after discussing with epidemiologist searchers, it appears that it is the number of larvae which can be estimated weeks by weeks. Thus, we will do an identifiability study for the novel ODEs-PDEs model with this assumption. Thanks to an integration of one of the model equations, some easier equations linking the inputs, outputs and parameters are obtained which really simplify the study of identifiability. From the identifiability study, a method and numerical procedure are proposed for estimating the parameters without any knowledge of them
Reis, Martina Costa 1986. "Constitutive modeling of electrochemical systems via the Müller-Liu entropy principle = Modelagem constitutiva de sistemas eletroquímicos através do princípio de entropia Müller-Liu." [s.n.], 2014. http://repositorio.unicamp.br/jspui/handle/REPOSIP/249906.
Повний текст джерелаTese (doutorado) - Universidade Estadual de Campinas, Instituto de Química
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Resumo: Este trabalho descreve a termodinâmica de sistemas eletroquímicos. Explorando os princípios da teoria constitutiva, algumas hipóteses ad hoc e, em especial, o princípio de entropia Müller-Liu, modelos termo-eletroquímicos são propostos para soluções eletrolíticas e para as regiões de bulk e dupla camada de um sistema eletroquímico. A influência das interações íon-íon e íon-solvente sobre a dinâmica da mistura é considerada através da termodinâmica de contínuos polares e as equações de balanço são apropriadamente postuladas. Além disso, equações fenomenológicas são apresentadas para uma solução eletrolítica diluída e isotrópica e as condições para o equilíbrio termodinâmico local do bulk e da dupla camada são investigadas. Comparando-se as desigualdades residuais de entropia obtidas para cada região, foi demonstrado que alguns processos, tais como os fenômenos de difusão térmica, termoeletricidade e eletroforese, desenvolvem-se somente na dupla camada. Consequentemente, o estado de equilíbrio termodinâmico local na dupla camada requer condições termodinâmicas mais severas do que no bulk. Apesar das equações constitutivas serem as mais simples possíveis, os modelos constitutivos propostos para as regiões de dupla camada e bulk são fisicamente consistentes e mais abrangentes do que os modelos eletroquímicos usuais, visto que as equações e relações termodinâmicas obtidas não se limitam às condições limites e nem de equilíbrio. Portanto, a descrição termodinâmica mostrada neste trabalho pode estimular químicos e engenheiros químicos a usar a abordagem contínua no estudo da mobilidade iônica em meios bio e geológicos, fluxos de íons e de outras espécies químicas através de membranas e processos cujas transferências de calor e massa são intensificadas por campos eletromagnéticos
Abstract: This work concerns the thermodynamics of electrochemical systems. Exploiting the principles of constitutive theory, few expedient assumptions, and, in special, the Müller-Liu entropy principle, a thermo-electrochemical continuum model is proposed for electrolyte solutions as well as for the bulk and double layer regions of an electrochemical system. The influence of ion-ion and ion-solvent interactions on the mixture dynamics is taken into account through the thermodynamics of polar materials and balance laws for an electrochemical system are accordingly stated. In addition, phenomenological equations are schemed for a dilute and isotropic electrolyte solution, and the conditions for local thermodynamic equilibrium of bulk and double layer regions are investigated. Comparing the residual entropy inequalities obtained for each region of an electrochemical system, it is shown that some mechanisms develop only in the double layer, such as the thermal diffusion, thermoelectricity and electrophoresis phenomena. As a consequence, the local thermodynamic equilibrium state in the double layer requires stricter conditions than in the bulk. Although the constitutive equations are the simplest possible, the constitutive models proposed for the double layer and bulk regions are physically consistent and more comprehensive than the usual models since the emerging equations do not constrain themselves to equilibrium neither limiting conditions. Therefore, the thermodynamic description provided in this work may stimulate chemists and chemical engineers to take advantage of it to study the flow of ions and other chemical species across cell membranes, ionic mobility in bio and geological media, and processes whose heat and mass transfers are enhanced by electromagnetic fields
Doutorado
Físico-Química
Doutora em Ciências
Woodward, Heather Kathleen. "A performance based, multi-process cost model for solid oxide fuel cells." Link to electronic thesis, 2003. http://www.wpi.edu/Pubs/ETD/Available/etd-0428103-235205.
Повний текст джерелаKeywords: Solid oxide fuel cell; SOFC; cost model; sputtering; tape casting; screen printing; performance model; process yield model. Includes bibliographical references (p. 93).
Radoszycki, Julia. "Résolution de processus décisionnels de Markov à espace d'état et d'action factorisés - Application en agroécologie." Thesis, Toulouse, INSA, 2015. http://www.theses.fr/2015ISAT0022/document.
Повний текст джерелаThis PhD thesis focuses on the resolution of problems of sequential decision makingunder uncertainty, modelled as Markov decision processes (MDP) whose state and actionspaces are both of high dimension. Resolution of these problems with a good compromisebetween quality of approximation and scaling is still a challenge. Algorithms for solvingthis type of problems are rare when the dimension of both spaces exceed 30, and imposecertain limits on the nature of the problems that can be represented.We proposed a new framework, called F3MDP, as well as associated approximateresolution algorithms. A F3MDP is a Markov decision process with factored state andaction spaces (FA-FMDP) whose solution policies are constrained to be in a certainfactored form, and can be stochastic. The algorithms we proposed belong to the familyof approximate policy iteration algorithms and make use of continuous optimisationtechniques, and inference methods for graphical models.These policy iteration algorithms have been validated on a large number of numericalexperiments. For small F3MDPs, for which the optimal global policy is available, theyprovide policy solutions that are close to the optimal global policy. For larger problemsfrom the graph-based Markov decision processes (GMDP) subclass, they are competitivewith state-of-the-art algorithms in terms of quality. We also show that our algorithmsallow to deal with F3MDPs of very large size outside the GMDP subclass, on toy problemsinspired by real problems in agronomy or ecology. The state and action spaces arethen both of dimension 100, and of size 2100. In this case, we compare the quality of thereturned policies with the one of expert policies. In the second part of the thesis, we applied the framework and the proposed algorithms to determine ecosystem services management strategies in an agricultural landscape.Weed species, ie wild plants of agricultural environments, have antagonistic functions,being at the same time in competition with the crop for resources and keystonespecies in trophic networks of agroecosystems. We seek to explore which organizationsof the landscape (here composed of oilseed rape, wheat and pasture) in space and timeallow to provide at the same time production services (production of cereals, fodder andhoney), regulation services (regulation of weed populations and wild pollinators) andcultural services (conservation of weed species and wild pollinators). We developed amodel for weeds and pollinators dynamics and for reward functions modelling differentobjectives (production, conservation of biodiversity or trade-off between services). Thestate space of this F3MDP is of size 32100, and the action space of size 3100, which meansthis F3MDP has substantial size. By solving this F3MDP, we identified various landscapeorganizations that allow to provide different sets of ecosystem services which differ inthe magnitude of each of the three classes of ecosystem services
Fan, Chih-Ming, and 范志銘. "Application of Mathematical Model and Physical Model in Ladle Refining and Continuous Casting Processes of Steel." Thesis, 2002. http://ndltd.ncl.edu.tw/handle/96636553685563930792.
Повний текст джерела國立成功大學
材料科學及工程學系碩博士班
91
The purpose of this study is to develop two mathematical models, which are based on a computational fluid dynamics technique, named SOLA, and the k-ε two-equation turbulence model, to analyze the fluid flow phenomena of molten steel in the ladle during the secondary refining process and the tundish operation in the continuous casting process of steel. The first mathematical model is used to analyze the fluid flow phenomena and the corresponding diffusion of the injected Ca-Si under various design and operating conditions to find the optimal Ca-Si injection position. The second mathematical model is used to analyze fluid flow phenomena and design the optimal flow control device during initial casting operation, steady state operation and ladle-interchange operation. Several physical models are also constructed in this study. Water model experiments are conducted to verify the accuracy and reliability of the mathematical models. Good agreements are observed between the simulations and measurements. As the mathematical model is verified to be a trustworthy tool, it is then applied to the actual operation to simulate the fluid flow; heat transfer and mass transfer phenomena of the secondary refining and continuous casting processes. The flow pattern of two-phase flow in the stirred ladle for the secondary refining is simulated. The results show that the injection position of D, which has the coordinate of , has the shortest mixing time. The simulated results for the actual ladle operation show the similar trend to the water model. For the injection positions on the tuyere/circle center plane, the additives prematurely float to the top as the injection positions are near the plume zone. It helps the additives to transport to the bottom as the injection positions are away from the plume zone. The simulated results for the actual ladle operation show that the optimal positions for injection are located on the tuyere/circle-center plane, opposite side of the tuyere, and 0.5-0.8 r away from the circle center. For these injection positions, the mixing time is shorter and the flow pattern favors the transport of the additive to the bottom of the ladle. The fluid flow and heat transfer phenomena of the molten steel in the tundish during its filling stage and subsequent initial casting operation are studied. The results show that the temperature field in LP-ND operation is not uniform Inclusion distribution and the extents of inclusion contamination among the outlets of the various strands in the tundish are also analyzed. The left half of tundish, inclusion contamination in the #2 strand is significantly more severe then that in the #1 strand. This is confirmed by the actual experience on the shop floor of that particular billet caster that the #2 strand experiences more difficulty in clogging problem during the initial casting operation than the #1 strand does. The LP-SD has no eddy near outlet strand and has more uniform temperature field. It shows that LP-SD lowers nozzle clogging and makes distribution of steel more uniform. The fluid flow and mass transfer phenomena of the molten steel in the three different tundish caster during steady state are studied. Three tundish caster include A-shaped four strands billet tundish, twin strand billet tundish, and single strands slab tundish. In A-shaped four strands billet tundish, HP-SB reduces the difference of residence times between two strands, and makes distribution of steel more uniform. In twin strands billet tundish, the billet tundish with the HLPP design has the longest min-RT and it can inhibit turbulence as well as guide flow upward along slag/metal interface in the tundish. It is thus considered that HLPP arrangement is the optimal SEFCD design for twin strands billet tundish. In the single strand slab tundish, the result shows that the plain tundish has short circuit and the lowest inclusion removal ratio. The tundish with PP can reduce short circuit and has the highest inclusion removal ratio, even for inclusions, which is smaller than 50 μm. PP is the optimal SEFCD design for the single strand slab tundish. The fluid flow and mass transfer phenomena of the molten steel in the tundish caster during ladle-change period are also studied. The results show that the weir and slanting dam reduce the velocity of steel and lower the chance for slag particles to flow into the outlet. WSLD40-F120 has the smallest number of slag particles to flow into the outlet and is considered the optimal flow control design in the T-shaped single strand slab tundish caster.
De, Wet Gideon Jacobus. "CFD Modelling and Mathematical Optimisation of a Continuous Caster Submerged Entry Nozzle." Diss., 2005. http://hdl.handle.net/2263/26212.
Повний текст джерелаDissertation (MEng (Mechanical Engineering))--University of Pretoria, 2007.
Mechanical and Aeronautical Engineering
unrestricted
Yeh, Jiunn-Lin, and 葉俊麟. "The Development of A Mathematical Model and Its Application in the Design/Operation of Tundishes for the Continuous Casting of Steel Slab." Thesis, 1993. http://ndltd.ncl.edu.tw/handle/19515081379711814706.
Повний текст джерелаYOU, MING-LONG, and 尤明隆. "Mathematical simulation of the macrosegregation in the continuous casting process." Thesis, 1989. http://ndltd.ncl.edu.tw/handle/25864880007034232188.
Повний текст джерела"Continuous-time portfolio optimization." 2004. http://library.cuhk.edu.hk/record=b6073673.
Повний текст джерела"July 2004."
Thesis (Ph.D.)--Chinese University of Hong Kong, 2004.
Includes bibliographical references (p. 133-139).
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Electronic reproduction. Ann Arbor, MI : ProQuest dissertations and theses, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web.
Mode of access: World Wide Web.
Abstracts in English and Chinese.
De, Kock Daniel Johannes. "Optimal Tundish design methodology in a continuous casting process." Thesis, 2005. http://hdl.handle.net/2263/28496.
Повний текст джерелаThesis (PhD (Mechanical Engineering))--University of Pretoria, 2006.
Mechanical and Aeronautical Engineering
unrestricted
Wong, Mungchen. "Is source memory continuous or discrete? : an Roc analysis." 2003. https://scholarworks.umass.edu/theses/2411.
Повний текст джерела"Continuous-time capital asset pricing model." Thesis, 2003. http://library.cuhk.edu.hk/record=b6073946.
Повний текст джерелаChiu Chun Hung.
"December 2003."
Adviser: Xun Yu Zhou.
Source: Dissertation Abstracts International, Volume: 64-11, Section: A, page: 4147.
Thesis (Ph.D.)--Chinese University of Hong Kong, 2003.
Includes bibliographical references (p. 185-187).
Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web.
Electronic reproduction. Ann Arbor, MI : ProQuest dissertations and theses, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web.
Electronic reproduction. Ann Arbor, MI : ProQuest Information and Learning Company, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web.
Abstracts in English and Chinese.
School code: 1307.
Chen, Yiming. "Modeling and simulation of a continuous fluidized-bed dryer." 1986. http://hdl.handle.net/2097/27603.
Повний текст джерелаPatil, Rohit A. "Novel application of quantitative risk assessment modelling to a continuous fermenter." Thesis, 2006. http://hdl.handle.net/2440/69737.
Повний текст джерелаThesis (M.Eng.Sc.) -- University of Adelaide, School of Chemical Engineering, 2006
Wang, Yan. "Mathematical modeling of heat transfer in the meniscus region of the continuous slab casting mould." Thesis, 1994. http://hdl.handle.net/2429/5012.
Повний текст джерелаBouhouche, Salah [Verfasser]. "Contribution to quality and process optimisation in continuous casting using mathematical modelling / vorgelegt von Salah Bouhouche." 2002. http://d-nb.info/966041208/34.
Повний текст джерела"Theoretical and numerical study on continuous-time mean-variance optimal strategies." 2006. http://library.cuhk.edu.hk/record=b5896528.
Повний текст джерелаThesis (M.Phil.)--Chinese University of Hong Kong, 2006.
Includes bibliographical references (leaves 87-88).
Abstracts in English and Chinese.
Chapter 1 --- Introduction --- p.1
Chapter 2 --- Literature Review --- p.8
Chapter 2.1 --- Markowitz´ةs Single-Period Mean-Variance Model --- p.9
Chapter 2.2 --- Discrete-Time Mean-Variance Problem --- p.10
Chapter 2.2.1 --- Optimal Buy-and-Hold Policy --- p.11
Chapter 2.2.2 --- Optimal Rolling Markowitz Policy --- p.12
Chapter 2.2.3 --- Multi-Period Mean-Variance Optimal Policy --- p.12
Chapter 2.3 --- Continuous-Time Market --- p.13
Chapter 2.3.1 --- Optimal Unconstrained Policy --- p.15
Chapter 2.3.2 --- Bankruptcy Prohibited Optimal Policy --- p.16
Chapter 2.3.3 --- No-Shorting Optimal Policy --- p.17
Chapter 2.4 --- Continuously Rebalancing Optimal Policy --- p.18
Chapter 3 --- Discretized Continuous-Time Optimal Policies --- p.20
Chapter 3.1 --- Problem Setup --- p.21
Chapter 3.2 --- Unconstrained Problem --- p.25
Chapter 3.3 --- Problem with No-shorting Constraint --- p.31
Chapter 3.4 --- Problem with No-Bankruptcy Constraint --- p.34
Chapter 3.4.1 --- Quasi No-Bankruptcy Problem --- p.36
Chapter 3.5 --- Stability of the Simulation --- p.38
Chapter 3.6 --- Concluding Remarks --- p.41
Chapter 4 --- Performance of Continuous-Time M-V Optimal Policies --- p.43
Chapter 4.1 --- Measures of the Performance by Probabilities --- p.45
Chapter 4.2 --- Performance of the Optimal Mean-Variance Portfolio --- p.51
Chapter 4.2.1 --- Target-Hitting Probability --- p.51
Chapter 4.2.2 --- Cut-Off Probability --- p.53
Chapter 4.2.3 --- Target-Hitting-before-Cut-Off Probability --- p.58
Chapter 4.3 --- Numerical Evaluations of Probabilities for Discrete-Time Market --- p.63
Chapter 4.3.1 --- Simulation on Target-Hitting Probability --- p.64
Chapter 4.3.2 --- Simulation on Zero-Hitting Probability --- p.66
Chapter 4.3.3 --- Simulation on Target-Hitting-before-Bankruptcy Probability --- p.67
Chapter 4.4 --- Policy Comparison --- p.68
Chapter 4.4.1 --- Profile of the Probabilities --- p.70
Chapter 4.4.2 --- Impact of z on the Probabilities --- p.72
Chapter 4.5 --- Concluding Remarks --- p.74
Chapter 5 --- Empirical Analysis --- p.75
Chapter 5.1 --- Experiment Description and Parameter Estimation --- p.76
Chapter 5.1.1 --- Introduction of the Data --- p.76
Chapter 5.1.2 --- Experiment Description --- p.77
Chapter 5.1.3 --- Parameter Estimation --- p.79
Chapter 5.2 --- Empirical Results and Analysis --- p.80
Chapter 5.2.1 --- Performance Indicator --- p.80
Chapter 5.2.2 --- Experimental Results and Analysis --- p.81
Chapter 5.3 --- Concluding Remarks --- p.83
Chapter 6 --- Summary --- p.84
Bibliography --- p.87
"Bidding strategies in agent based continuous double auctions." Thesis, 2006. http://library.cuhk.edu.hk/record=b6074300.
Повний текст джерелаIn this thesis, we focus on two types of CDAs. One is the CDAs with a deadline of inactive interval. Another is the CDAs with a fixed deadline. Three kinds of adaptive behaviors are proposed to enhance the performance of the widely adopted strategies in CDAs in the literature. They are adaptive softness, adaptive judgment of price acceptability, and adaptive time strategies. First, in the CDAs with a deadline of inactive interval, we design novel adaptive strategies, named Adaptive Attitude strategies, based on eagerness. Eagerness indicates the current supply and demand relationship from the agent's own point of view. To compute the value of eagerness, fuzzy sets and fuzzy logic are used to cope with the significant degrees of uncertainty in CDA markets. We define two kinds of adaptive behaviors, adaptive softness and adaptive judgment of price acceptability. Both of them resemble human traders' behaviors to compromise and set thresholds on acceptable prices in the trading process of real life markets and can enhance the performance of various strategies. Secondly, in the CDAs with a fixed deadline, time strategies are researched by us. In this market, every agent is aware of the time. Therefore adaptive time strategies are introduced to guide the agent to arrange his behavior according to time, which can enhance the performance of different strategies. Both the novel strategies and the enhanced strategies have been demonstrated to be superior in a wide range of CDA circumstances. We show that eagerness is a, practical solution for this class of application. We believe that this work represents an important step towards adapting agents in auctions.
Through the work in this thesis, Adaptive Attitude (AA) strategies have been demonstrated to be superior in a wide range of CDA scenarios. Moreover, three kinds of adaptive behaviors have been shown to greatly enhance the performance of the widely adopted strategies in CDAs.
Ma Huiye.
"August 2006."
Adviser: Ho Fung Leung.
Source: Dissertation Abstracts International, Volume: 68-03, Section: B, page: 1731.
Thesis (Ph.D.)--Chinese University of Hong Kong, 2006.
Includes bibliographical references (p. 151-162).
Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web.
Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web.
Abstracts in English and Chinese.
School code: 1307.
Mustafa, Nizar Ahmad. "Numerical simulation of anaerobic reductive dechlorination of CAHs in continuous flow systems." Thesis, 2011. http://hdl.handle.net/1957/27539.
Повний текст джерелаGraduation date: 2012
"Continuous-time mean-variance portfolio selection with proportional transaction costs." Thesis, 2007. http://library.cuhk.edu.hk/record=b6074183.
Повний текст джерелаWe study continuous-time Markowitz's mean-variance portfolio selection problem in a market with one stock, one bond and proportional transaction costs. The presence of transaction costs makes the problem being a singular control problem in a finite time horizon, which is very hard to deal with from the point view of control theory. Using a partial differential equation approach, we formulate the problem as a double obstacle problem, and prove the smoothness of the value function. Then we give the necessary and sufficient conditions for the existence of an optimal solution and completely characterize the optimal strategy when the problem is feasible. We show three critical distinctive features of the Markowitz model under the presence of transaction costs. First, the expected return on the portfolio could be too high to achieve if the time to maturity is not long enough, while without transaction costs, any expected return can be reached in an arbitrary short time. Second, instead of keeping the investment ratio between stock and bond to be a constant, there exists time-dependent upper and lower boundaries, transaction is carried out only if the investment ratio is on the boundaries. Third, there exists a critical time, which only depends on the market parameters, such that beyond the time no more investment will be added to stock holding. Our result is closer to real investment practice where people tend not to invest on risky assets towards the end of the investment horizon.
Xu Zuoquan.
"January 2007."
Adviser: Xunyu Zhou.
Source: Dissertation Abstracts International, Volume: 68-08, Section: B, page: 5290.
Thesis (Ph.D.)--Chinese University of Hong Kong, 2007.
Includes bibliographical references (p. 118-123).
Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web.
Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web.
Abstracts in English and Chinese.
School code: 1307.
Ahmad, Maysoon. "Assessment of mathematical models for ultrafiltration of multi-solute continuous cross-flow process." Thesis, 2012. http://hdl.handle.net/10012/6658.
Повний текст джерелаReinlie, Shinta Tjahyaningtyas. "Analysis of continuous monitoring data and rapid, stochastic updating of reservoir models." Thesis, 2006. http://hdl.handle.net/2152/2625.
Повний текст джерелаChe, Xuan. "Spatial graphical models with discrete and continuous components." Thesis, 2012. http://hdl.handle.net/1957/33644.
Повний текст джерелаGraduation date: 2013
"Unsupervised model adaptation for continuous speech recognition using model-level confidence measures." 2002. http://library.cuhk.edu.hk/record=b5891033.
Повний текст джерелаThesis (M.Phil.)--Chinese University of Hong Kong, 2002.
Includes bibliographical references.
Abstracts in English and Chinese.
Chapter 1. --- Introduction --- p.1
Chapter 1.1. --- Automatic Speech Recognition --- p.1
Chapter 1.2. --- Robustness of ASR Systems --- p.3
Chapter 1.3. --- Model Adaptation for Robust ASR --- p.4
Chapter 1.4. --- Thesis outline --- p.6
References --- p.8
Chapter 2. --- Fundamentals of Continuous Speech Recognition --- p.10
Chapter 2.1. --- Acoustic Front-End --- p.10
Chapter 2.2. --- Recognition Module --- p.11
Chapter 2.2.1. --- Acoustic Modeling with HMM --- p.12
Chapter 2.2.2. --- Basic Phonology of Cantonese --- p.14
Chapter 2.2.3. --- Acoustic Modeling for Cantonese --- p.15
Chapter 2.2.4. --- Language Modeling --- p.16
References --- p.17
Chapter 3. --- Unsupervised Model Adaptation --- p.18
Chapter 3.1. --- A General Review of Model Adaptation --- p.18
Chapter 3.1.1. --- Supervised and Unsupervised Adaptation --- p.20
Chapter 3.1.2. --- N-Best Adaptation --- p.22
Chapter 3.2. --- MAP --- p.23
Chapter 3.3. --- MLLR --- p.25
Chapter 3.3.1. --- Adaptation Approach --- p.26
Chapter 3.3.2. --- Estimation of MLLR regression matrices --- p.27
Chapter 3.3.3. --- Least Mean Squares Regression --- p.29
Chapter 3.3.4. --- Number of Transformations --- p.30
Chapter 3.4. --- Experiment Results --- p.32
Chapter 3.4.1. --- Standard MLLR versus LMS MLLR --- p.36
Chapter 3.4.2. --- Effect of the Number of Transformations --- p.43
Chapter 3.4.3. --- MAP Vs. MLLR --- p.46
Chapter 3.5. --- Conclusions --- p.48
Referencesxlix
Chapter 4. --- Use of Confidence Measure for MLLR based Adaptation --- p.50
Chapter 4.1. --- Introduction to Confidence Measure --- p.50
Chapter 4.2. --- Confidence Measure Based on Word Density --- p.51
Chapter 4.3. --- Model-level confidence measure --- p.53
Chapter 4.4. --- Integrating Confusion Information into Confidence Measure --- p.55
Chapter 4.5. --- Adaptation Data Distributions in Different Confidence Measures..… --- p.57
References --- p.65
Chapter 5. --- Experimental Results and Analysis --- p.66
Chapter 5.1. --- Supervised Adaptation --- p.67
Chapter 5.2. --- Cheated Confidence Measure --- p.69
Chapter 5.3. --- Confidence Measures of Different Levels --- p.71
Chapter 5.4. --- Incorporation of Confusion Matrix --- p.81
Chapter 5.5. --- Conclusions --- p.83
Chapter 6. --- Conclusions --- p.35
Chapter 6.1. --- Future Works --- p.88
Thaba, Lethabo Jane. "Modelling the short term interest with stochastic differential equation in continuous time: linear versus non-linear mode." Thesis, 2014. http://hdl.handle.net/10210/11137.
Повний текст джерелаRecently, there has been a growth in the bond market. This growth has brought with it an ever-increasing volume and range of interest rate depended derivative products known as interest rate derivatives. Amongst the variables used in pricing these derivative products is the short-term interest rate. A numbers of short-term interest rate models that are used to fit the short-term interest rate exist. Therefore, understanding the features characterised by various short-term interest rate models, and determining the best fitting models is crucial as this variable is fundamental in pricing interest rate derivatives, which further determine the decision making of economic agents. This dissertation examines various short-term interest rate models in continuous time in order to determine which model best fits the South African short-term interest rates. Both the linear and nonlinear short-term interest rate models were estimated. The methodology adopted in estimating the models was parametric approach using Quasi Maximum Likelihood Estimation (QMLE). The findings indicate that nonlinear models seem to fit the South African short-term interest rate data better than the linear models
Love, David John. "Dynamic modelling and optimal control of sugar crystallisation in a multi-compartment continuous vacuum pan." Thesis, 2002. http://hdl.handle.net/10413/610.
Повний текст джерелаThesis (Ph.D.)-University of Natal, 2002.
Van, Appel Vaughan. "Estimation of discretely sampled continuous diffusion processes with application to short-term interest rate models." Thesis, 2014. http://hdl.handle.net/10210/12372.
Повний текст джерелаStochastic Differential Equations (SDE’s) are commonly found in most of the modern finance used today. In this dissertation we use SDE’s to model a random phenomenon known as the short-term interest rate where the explanatory power of a particular short-term interest rate model is largely dependent on the description of the SDE to the real data. The challenge we face is that in most cases the transition density functions of these models are unknown and therefore, we need to find reliable and accurate alternative estimation techniques. In this dissertation, we discuss estimating techniques for discretely sampled continuous diffusion processes that do not require the true transition density function to be known. Moreover, the reader is introduced to the following techniques: (i) continuous time maximum likelihood estimation; (ii) discrete time maximum likelihood estimation; and (iii) estimating functions. We show through a Monte Carlo simulation study that the parameter estimates obtained from these techniques provide a good approximation to the estimates obtained from the true transition density. We also show that the bias in the mean reversion parameter can be reduced by implementing the jackknife bias reduction technique. Furthermore, the data analysis carried out on South-African interest rate data indicate strongly that single factor models do not explain the variability in the short-term interest rate. This may indicate the possibility of distinct jumps in the South-African interest rate market. Therefore, we leave the reader with the notion of incorporating jumps into a SDE framework.
"Improved estimation of catchment rainfall for continuous simulation modelling." Thesis, 2005. http://hdl.handle.net/10413/2685.
Повний текст джерелаThesis (M.Sc.)-University of KwaZulu-Natal, 2005.
Mashau, Shivasi Christopher. "An investigation into the manufacturing of complex, three-dimensional components using continuous fibre reinforced thermoplastic composites." Thesis, 2017. https://hdl.handle.net/10539/24191.
Повний текст джерелаThis research looks into the manufacturing process of complex geometries using continuous fibre reinforced thermoplastics (CFRTP). The purpose of this work was to develop methods that will enable the production of defect free complex components. This was achieved by investigating the key process parameters in the CFRTP manufacturing process, and optimizing them in order to improve the quality of components. The investi- gations were performed with the aid of software making use of the finite element method, and this was found to be instrumental in predicting the formability of geometries. The re- search showed that the formability of complex geometry is largely determined by the ability of the laminate to be draped into the required geometry. The forming mechanisms that take place during the draping process can be linked to the formation of defects where draping is unsuccessful. The study also showed that the quality of the drape can be influenced by blank and tool design factors. It was also shown that the blank can be manipulated using a restraint mechanism to improve the formability of geometries. The effect of processing parameters such as forming speed, forming pressure and tool temperature were also investigated. The research resulted in the formulation of guidelines to follow when manufacturing CFRTP components. The developments that were made were successfully implemented to improve the formability of a complex component that had previously been difficult to form without defects.
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