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Thèses sur le sujet « Gradient problem of C »

Auteur : Grafiati

Publié le 4 juin 2021

Mis à jour le 5 février 2022

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1

Dagher, Issam J. « Gradient based fuzzy c-means algorithm ». FIU Digital Commons, 1994. http://digitalcommons.fiu.edu/etd/2652.

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A clustering algorithm based on the Fuzzy c-means algorithm (FCM) and the gradient descent method is presented. In the FCM, the minimization process of the objective function is proceeded by solving two equations alternatively in an iterative fashion. Each iteration requires the use of all the data at once. In our proposed approach one datum is presented at a time to the network and the minimization is proceeded using the gradient descent method. Compared to FCM, the experimental results show that our algorithm is very competitive in terms of speed and stability of convergence for large number of data.

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2

Li, Futong. « Global Optimization Techniques Based on Swarm-intelligent and Gradient-free Algorithms ». Thesis, Université d'Ottawa / University of Ottawa, 2021. http://hdl.handle.net/10393/42307.

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The need for solving nonlinear optimization problems is pervasive in many fields. Particle swarm optimization, advantageous with the simple underlying implementation logic, and simultaneous perturbation stochastic approximation, which is famous for its saving in the computational power with the gradient-free attribute, are two solutions that deserve attention. Many researchers have exploited their merits in widely challenging applications. However, there is a known fact that both of them suffer from a severe drawback, non- effectively converging to the global best solution, because of the local “traps” spreading on the searching space. In this article, we propose two approaches to remedy this issue by combined their advantages. In the first algorithm, the gradient information helps optimize half of the particles at the initialization stage and then further updates the global best position. If the global best position is located in one of the local optima, the searching surface’s additional gradient estimation can help it jump out. The second algorithm expands the implementation of the gradient information to all the particles in the swarm to obtain the optimized personal best position. Both have to obey the rule created for updating the particle(s); that is, the solution found after employing the gradient information to the particle(s) has to perform more optimally. In this work, the experiments include five cases. The three previous methods with a similar theoretical basis and the two basic algorithms take participants in all five. The experimental results prove that the proposed two algorithms effectively improved the basic algorithms and even outperformed the previously designed three algorithms in some scenarios.

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3

Eklund, Per-Olof. « Psykosociala problem vid hepatit C ». Thesis, Malmö högskola, Fakulteten för hälsa och samhälle (HS), 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:mau:diva-26624.

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Vissa sjukdomar för konsekvenser med sig utöver den somatiska bördan. Hepatit C är en av dessa. Detta virus påverkar den drabbades liv på ett sätt som står över den patologiska beskrivningen. Varje år anmäls 2000 fall av hepatit C i Sverige. Syftet med denna litteraturstudie var att få kunskap om omfattningen av psykosociala problem hos hepatit C-smittade. Litteraturstudien grundar sig på sju vetenskapliga artiklar. Forskningsprocessen inspirerades av Goodmans sju olika steg. Som teoretisk referensram har använts Carnevalis modell för ett funktionellt hälsotillstånd i dagligt liv. Resultatet presenteras genom fyra olika teman som identifierades under artikelgranskningen: (1) Stigmatisering av individer med hepatit C, (2) rädsla förknippad med hepatit C, (3) Depressiva symtom förknippade med hepatit C och (4) Bristande socialt stöd vid hepatit. Resultatet pekar på att hepatit C-smittade i stor omfattning upplever psykosociala problem. Detta medför att den smittades livssituation påverkas negativt och därmed minskar dennes möjlighet till att uppleva hälsa.
Certain diseases carry consequences beyond the somatic burden. Hepatitis C is one of them. This virus influences the infected beyond its pathological description. Every year 2000 cases of Hepatitis C are reported in Sweden. The aim of this study was to illuminate the extent and character of psychosocial problems in patients with the diagnosis hepatitis C. The study is based on seven scientific articles. The seven steps for a literature study presented by Goodman inspired the research process. As a theoretical frame of reference Carnevali´s model for a functional and healthy daily life has been used. The analysis resulted in four themes: (1) Stigmatization, (2) fear associated with hepatitis C, (3) depressive symptoms connected with the diagnosis and (4) lack of social support The results indicate that patients with the diagnosis hepatitis C experience psychosocial problems to a larger extent. This also means that these patients are negatively influenced leading to a decreased opportunity to experience health.

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4

Matthes, H. « Parallel Preconditioners for Plate Problem ». Universitätsbibliothek Chemnitz, 1998. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-199800826.

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This paper concerns the solution of plate bending problems in domains composed of rectangles. Domain decomposition (DD) is the basic tool used for both the parallelization of the conjugate gradient method and the construction of efficient parallel preconditioners. A so-called Dirich- let DD preconditioner for systems of linear equations arising from the fi- nite element approximation by non-conforming Adini elements is derived. It is based on the non-overlapping DD, a multilevel preconditioner for the Schur-complement and a fast, almost direct solution method for the Dirichlet problem in rectangular domains based on fast Fourier transform. Making use of Xu's theory of the auxiliary space method we construct an optimal preconditioner for plate problems discretized by conforming Bogner-Fox-Schmidt rectangles. Results of numerical experiments carried out on a multiprocessor sys- tem are given. For the test problems considered the number of iterations is bounded independent of the mesh sizes and independent of the number of subdomains. The resulting parallel preconditioned conjugate gradient method requiresO(h^-2 ln h^-1 ln epsilon^-11) arithmetical operations per processor in order to solve the finite element equations with the relative accuracy epsilon.

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5

Scipolo, Vittorio. « Scattered neutron tomography based on a neutron transport problem ». Texas A&M University, 2004. http://hdl.handle.net/1969.1/2791.

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Tomography refers to the cross-sectional imaging of an object from either transmission or reflection data collected by illuminating the object from many different directions. Classical tomography fails to reconstruct the optical properties of thick scattering objects because it does not adequately account for the scattering component of the neutron beam intensity exiting the sample. We proposed a new method of computed tomography which employs an inverse problem analysis of both the transmitted and scattered images generated from a beam passing through an optically thick object. This inverse problem makes use of a computationally efficient, two-dimensional forward problem based on neutron transport theory that effectively calculates the detector readings around the edges of an object. The forward problem solution uses a Step-Characteristic (SC) code with known uncollided source per cell, zero boundary flux condition and Sn discretization for the angular dependence. The calculation of the uncollided sources is performed by using an accurate discretization scheme given properties and position of the incoming beam and beam collimator. The detector predictions are obtained considering both the collided and uncollided components of the incoming radiation. The inverse problem is referred as an optimization problem. The function to be minimized, called an objective function, is calculated as the normalized-squared error between predicted and measured data. The predicted data are calculated by assuming a uniform distribution for the optical properties of the object. The objective function depends directly on the optical properties of the object; therefore, by minimizing it, the correct property distribution can be found. The minimization of this multidimensional function is performed with the Polack Ribiere conjugate-gradient technique that makes use of the gradient of the function with respect to the cross sections of the internal cells of the domain. The forward and inverse models have been successfully tested against numerical results obtained with MCNP (Monte Carlo Neutral Particles) showing excellent agreements. The reconstructions of several objects were successful. In the case of a single intrusion, TNTs (Tomography Neutron Transport using Scattering) was always able to detect the intrusion. In the case of the double body object, TNTs was able to reconstruct partially the optical distribution. The most important defect, in terms of gradient, was correctly located and reconstructed. Difficulties were discovered in the location and reconstruction of the second defect. Nevertheless, the results are exceptional considering they were obtained by lightening the object from only one side. The use of multiple beams around the object will significantly improve the capability of TNTs since it increases the number of constraints for the minimization problem.

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6

Hua, Xiaoqin. « Studies on block coordinate gradient methods for nonlinear optimization problems with separable structure ». 京都大学 (Kyoto University), 2015. http://hdl.handle.net/2433/199447.

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7

Stevenson, George Stuart Michael. « The Women's Liberation Movement and the intractable problem of class, c.1968 - c.1979 ». Thesis, Durham University, 2016. http://etheses.dur.ac.uk/11430/.

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This thesis focuses on the voices, activism and experiences of working-class women engaged with the Women’s Movement between 1968 and 1979. It explores their interactions with feminism and class politics and places particular emphasis on their role in the Women’s Liberation Movement and the productive and reproductive class struggles in the period. This approach defines the WLM as a part of the wider Women’s Movement, alongside women’s industrial and community conflicts. It argues that contemporary accounts seeking to recover the significance of ‘sisterhood’ or prioritise alternative identities in the movement often do so at the expense of its working-class participants and underplay the significance of ‘class’ in the political identities of middle-class liberationists. It asserts therefore that that the integration of working-class women and class politics into the story of the 1970s Women’s Movement requires a reconsideration of the existing narratives of the WLM. In developing this perspective, it extricates the tension between the foundational and ideological importance of class and class politics at individual, regional and national levels of the WLM in Britain on the one hand and the intractable problems that class posed within and around the movement on the other. In so doing, it illustrates how both structural and cultural forms of class analysis can offer complementary insights into women’s identity construction and political consciousness, with particular validity not only for social and political movements but also for the post-war period more widely.

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8

Marschner, David Emmanuel [Verfasser], et C. [Akademischer Betreuer] Barner-Kowollik. « Wavelength-Orthogonal Approaches Enabling Reprogrammable Gradient Materials / David Emmanuel Marschner ; Betreuer : C. Barner-Kowollik ». Karlsruhe : KIT-Bibliothek, 2019. http://d-nb.info/1196208670/34.

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9

Marschner, David [Verfasser], et C. [Akademischer Betreuer] Barner-Kowollik. « Wavelength-Orthogonal Approaches Enabling Reprogrammable Gradient Materials / David Emmanuel Marschner ; Betreuer : C. Barner-Kowollik ». Karlsruhe : KIT-Bibliothek, 2019. http://d-nb.info/1196208670/34.

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10

Skoglund, Ingegerd. « Algorithms for a Partially Regularized Least Squares Problem ». Licentiate thesis, Linköping : Linköpings universitet, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-8784.

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11

Bormann, Stefanie [Verfasser], et A. C. B. [Akademischer Betreuer] Cato. « Anterior Gradient 2 Genprodukte als Marker und Regulatoren der Prostatakrebsprogression / Stefanie Bormann. Betreuer : A. C. B. Cato ». Karlsruhe : KIT-Bibliothek, 2012. http://d-nb.info/102308175X/34.

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12

Xin, Jiping [Verfasser], et C. [Akademischer Betreuer] Wieners. « Boundary Element Approximation for Maxwell's Eigenvalue Problem / Jiping Xin. Betreuer : C. Wieners ». Karlsruhe : KIT-Bibliothek, 2011. http://d-nb.info/1015557899/34.

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13

Thomson, Mathew P. « The problem of mental deficiency in England and Wales, c. 1913-1946 ». Thesis, University of Oxford, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.316833.

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14

Kelly, J. G. « The problem of anti-slavery in the 'age of capital', c. 1830-1888 ». Thesis, University of Liverpool, 2017. http://livrepository.liverpool.ac.uk/3019963/.

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This thesis explores the relationship between Britain and transatlantic slavery in the post-emancipation period. Following West Indian emancipation various types of British capitalists continued to profit from both the slave trade and slave-ownership. These economic connections had to be rationalised within a Britain politically and ideologically committed to anti-slavery. I propose that the British government, abolitionists, and capitalists were faced with the problem of anti-slavery, namely the question of whether it was possible to operate morally in an Atlantic economy built upon chattel slavery. I explore a number of controversies relating to both British slave-ownership and involvement in the transatlantic slave trade. I argue that these debates must be considered as part of a longer tradition of slavery apologism that stretched back to the struggles over slave trade abolition and West Indian emancipation. In doing so I complicate our understanding of Britain as anti-slavery nation. Debates over British involvement of in transatlantic slavery blended economic and moral arguments. As such my thesis stresses the historically contingent nature of appeals to economic rationality, a key strategy of British capitalists justifying profiting from slavery. By examining business records, private correspondence, and government papers I establish the material basis of British involvement with transatlantic slavery. I also analyse debates that took place in newspapers, journals, and parliament to explore the arguments advanced about Britain, commerce, and slavery. I demonstrate how British capitalists justified profiting from transatlantic slavery through a construction of Britons as more civilized than foreign slave owners, slave traders, and enslaved people. That this imagined geography provided a solution the problem of anti-slavery speaks to the heterogeneous nature of anti-slavery ideology in Victorian Britain.

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15

Duminy, James. « Scarcity, government, population : The problem of food in colonial Kenya, c. 1900-1952 ». Doctoral thesis, University of Cape Town, 2018. http://hdl.handle.net/11427/27837.

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Food security in Africa is a foremost development challenge. Dominant approaches to addressing food security concentrate on availability and increasing production. This 'productionist' focus arguably limits the capacity of government policies to address contemporary food problems. It does so by obscuring both the specific food insecurity dynamics linked to the continent's ongoing urban transitions, as well as the potential for more systemic food strategies. Yet existing research provides an inadequate historical understanding of how a production and supply-oriented bias has emerged and become established in the African context. This undermines the capacity of scholars and policymakers to critique and reform food security thought and practice. The thesis addresses this gap in knowledge by critically and historically examining the emergence of food scarcity as a specific problem of government in a particular African context: colonial Kenya. Understanding how colonial officials and other actors conceived of and responded to food scarcities in Kenya is the primary question addressed. The specific roles and duties of the state in relation to this problem are also investigated. The thesis employs a Foucauldian-inspired approach to the historical analysis of government and problematizations. Primary data were gathered from archives in the United Kingdom. The argument is that food scarcity, as a problem of government, shifted from an uncertain and localized rural issue to a risk encompassing the balance between market supply and demand at a territorial scale. The role of the state shifted from a last-resort provider of relief to a regulator of maize production and demand, with a focus on ensuring adequate supply for territorial self-sufficiency. Accordingly, anti-scarcity techniques became increasingly economic and calculative in nature, and longer term in focus. This mode of conceiving and addressing food scarcity existed in Kenya by the end of the Second World War, and was stabilized in the immediate post-war period. Elements of this system are recognizable in contemporary food security policies in Kenya and elsewhere in Africa. The thesis contributes to historical knowledge of African food insecurity and colonial government. It moves beyond previous work by focusing on Kenya, and by examining food scarcity as a distinct problem of colonial government. It enhances knowledge of the conditions under which contemporary modes of food governance have come into existence.

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Feron, Pierre. « Schémas gradients appliqués à des problèmes elliptiques et paraboliques, linéaires et non-linéaires ». Thesis, Paris Est, 2015. http://www.theses.fr/2015PESC1119/document.

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La notion de schémas gradients, conçue pour les équations elliptiques et paraboliques, linéaires et non-linéaires a l'avantage de fournir des résultats de convergence et d'estimations d'erreur valables pour de nombreuses familles de méthodes numériques (éléments finis conformes et non-conformes, éléments finis mixtes, différences finies ...). Vérifier un ensemble restreint de propriétés suffit pour prouver qu'une méthode numérique donnée rentre dans le cadre de travail des schémas gradients et donc qu'elle sera convergente sur les différents problèmes traités. L'étude du problème de Stefan, celle du problème de Stokes incompressible, ainsi que celle des équations de Navier-Stokes incompressibles sont présentées dans cette thèse, chacune présentant un théorème de convergence établi à l'aide des schémas gradients. Pour Stokes et Navier-Stokes, nous donnerons une preuve de convergence pour les cas stationnaires et transitoires en modifiant certaines hypothèses ce qui aura comme effet de trouver des résultats de convergence différents. Finalement, nous présentons également quatre méthodes (Taylor-Hood, Crouzeix-Raviart, Marker-and-Cell, Hybrid Mixed Mimetic) pour ces deux problèmes et nous vérifions qu'elles rentrent bien dans le cadre des schémas gradients
The notion of gradient schemes, designed for linear and nonlinear elliptic and parabolic problems has the benefit of providing common convergence and error estimates results, which hold for a wide variety of numerical methods (finite element methods, nonconforming and mixed finite element methods, hybrid and mixed mimetic finite difference methods ...). Checking a minimal set of properties for a given numerical method suffices to prove that it belongs to the gradient schemes framework, and therefore that it is convergent on the different problems studied here. The study of the Stefan problem, the incompressible Stokes one and also the incompressible Navier-Stokes equations are presented in this thesis, where each one gets a convergence theorem set up with the gradient schemes framework. For Stokes and Navier-Stokes, we both provide the proof for the steady and the transient case dealing with some variational hypotheses which bring different convergence results. Finally, we also present four methods (Taylor-Hood, Crouzeix-Raviart, Marker-and-Cell, Hybrid Mixed Mimetic) for these two problems and we check that they enter in the gradient schemes framework

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17

Carlsson, Fredrik. « Utilizing Problem Structure in Optimization of Radiation Therapy ». Doctoral thesis, Stockholm : Matematik, Kungliga Tekniska högskolan, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4689.

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18

Barshinger, David. « Pain in C.S. Lewis an evaluation of The problem of pain and A grief observed / ». Theological Research Exchange Network (TREN), 2006. http://www.tren.com/search.cfm?p001-1078.

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19

Carpentier, Arnaud. « Production de virus de l'hépatite C infectieux en culture primaire d'hépatocytes humains adultes ». Paris 6, 2009. http://www.theses.fr/2009PA066375.

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L’infection par le Virus de l’Hépatite C (VHC) représente un grave problème de santé publique à travers le monde. Bien que la production de virus en culture cellulaire (VHCcc) ait été rendue possible en utilisant des sous clones de la lignée Huh7 issue d’un hépatocarcinome humain, les recherches basiques et appliquées sur le virus restent pénalisées par l’absence d’un modèle de culture cellulaire capable de reproduire le cycle viral complet dans les cellules hôtes naturelles du VHC, c'est-à-dire les hépatocytes humains primaires, cellules normales, quiescentes et hautement différenciées. Ici nous avons développé un système permettant de cultiver le VHC en culture primaire d’hépatocytes humains adultes. Tout en maintenant l’expression de leurs marqueurs de différenciation, les hépatocytes humains primaires inoculés avec des particules virales VHCcc permettaient une réplication intracellulaire forte du génome viral. Surtout, ces hépatocytes normaux produisaient de nouveaux virions infectieux (appelés VHCpc, pour virus produits en culture primaire) avec des titres comparables à ceux obtenus avec les cellules transformées Huh7. Cependant, les VHCpc présentaient une meilleure infectiosité spécifique et une densité plus faible que les VHCcc, reproduisant plus précisément les caractéristiques des complexes virus/lipoprotéines produits durant l’infection in vivo. Ces deux propriétés étaient perdues après re-culture en cellules Huh7, suggérant que les virions authentiques ne peuvent être produits qu’en culture d’hépatocytes normaux. En conclusion, nous avons établi un système de culture cellulaire simple mais robuste permettant de reproduire le cycle viral complet du VHC dans des hépatocytes humains hautement différenciés, constituant ainsi un modèle in vitro plus pertinent pour l’étude des interactions du VHC avec sa cellule hôte naturelle et permettant la validation de traitements antiviraux candidats dans le contexte d’une physiologie hépatocytaire authentique.

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Croyle, Laura D. « Solutions to the L^p Mixed Boundary Value Problem in C^1,1 Domains ». UKnowledge, 2016. http://uknowledge.uky.edu/math_etds/38.

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We look at the mixed boundary value problem for elliptic operators in a bounded C1,1(ℝn) domain. The boundary is decomposed into disjoint parts, D and N, with Dirichlet and Neumann data, respectively. Expanding on work done by Ott and Brown, we find a larger range of values of p, 1 < p < n/(n-1), for which the Lp mixed problem has a unique solution with the non-tangential maximal function of the gradient in Lp(∂Ω).

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21

Root, Gerald Richard. « C. S. Lewis and a problem of evil : an investigation of a pervasive theme ». Thesis, Open University, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.412861.

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Gratien, Jean-Marc. « A DSEL in C++ for lowest-order methods for diffusive problem on general meshes ». Thesis, Grenoble, 2013. http://www.theses.fr/2013GRENM018/document.

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Les simulateurs industriels deviennent de plus en plus complexes car ils doivent intégrer de façon performante des modèles physiques complets et des méthodes de discrétisation évoluées. Leur mise au point nécessite de gérer de manière efficace la complexité des modèles physiques sous-jacents, la complexité des méthodes numériques utilisées, la complexité des services numériques de bas niveau nécessaires pour tirer parti des architectures matérielle modernes et la complexité liée aux langages informatiques. Une réponse partielle au problème est aujourd'hui fournie par des plate-formes qui proposent des outils avancés pour gérer de façon transparente la complexité liée au parallélisme. Cependant elles ne gèrent que la complexité du matériel et les services numériques de bas niveau comme l'algèbre linéaire. Dans le contexte des méthodes Éléments Finis (EF), l'existence d'un cadre mathématique unifié a permis d'envisager des outils qui permettent d'aborder aussi la complexité issue des méthodes numériques et celle liée aux problèmes physiques, citons, par exemple, les projets Freefem++, Getdp, Getfem++, Sundance, Feel++ et Fenics. Le travail de thèse a consisté à étendre cette approche aux méthodes d'ordre bas pour des systèmes d'EDPs, méthodes qui souffraient jusqu'à maintenant d'une absence d'un cadre suffisamment général permettant son extension à des problèmes différents. Des travaux récents ont résolue cette difficulté, par l'introduction d'une nouvelle classe de méthodes d'ordre bas inspirée par les éléments finis non conformes. Cette formulation permet d'exprimer dans un cadre unifié les schémas VF multi-points et les méthodes DFM/VFMH. Ce nouveau cadre a permis la mise au point d'un langage spécifique DSEL en C++ qui permet de développer des applications avec un haut niveau d'abstraction, cachant la complexité des méthodes numériques et des services bas niveau garanties de haute performances. La syntaxe et les techniques utilisées sont inspirée par celles de Feel++. Le DSEL a été développé à partir de la plate-forme Arcane, et embarqué dans le C++. Les techniques de DSEL permettent de représenter un problème et sa méthode de résolution avec une expression, parsée à la compilation pour générer un programme, et évaluée à l'exécution pour construire un système linéaire que l'on peut résoudre pour trouver la solution du problème. Nous avons mis au point notre DSEL à l'aide d'outils standard issus de la bibliothèque Boost puis l'avons validé sur divers problèmes académiques non triviaux tels que des problèmes de diffusion hétérogène et le problème de Stokes. Dans un deuxième temps, dans le cadre du projet ANR HAMM (Hybrid Architecture and Multiscale Methods), nous avons validé notre approche en complexifiant le type de méthodes abordées et le type d'architecture matérielle cible pour nos programmes. Nous avons étendu le formalisme mathématique sur lequel nous nous basons pour pouvoir écrire des méthodes multi-échelle puis nous avons enrichi notre DSEL pour pouvoir implémenter de telles méthodes. Afin de pouvoir tirer partie de façon transparente des performances de ressources issues d'architectures hybrides proposant des cartes graphiques de type GPGPU, nous avons mis au point une couche abstraite proposant un modèle de programmation unifié qui permet d'accéder à différents niveaux de parallélisme plus ou moins fin en fonction des spécificités de l'architecture matérielle cible. Nous avons validé cette approche en évaluant les performances de cas tests utilisant des méthodes multi-échelle sur des configurations variés de machines hétérogènes. Pour finir nous avons implémenté des applications variées de type diffusion-advection-réaction, de Navier-Stokes incompressible et de type réservoir. Nous avons validé la flexibilité de notre approche et la capacité qu'elle offre à appréhender des problèmes variés puis avons étudié les performances des diverses implémentations
Industrial simulation software has to manage : the complexity of the underlying physical models, usually expressed in terms of a PDE system completed with algebraic closure laws, the complexity of numerical methods used to solve the PDE systems, and finally the complexity of the low level computer science services required to have efficient software on modern hardware. Nowadays, this complexity management becomes a key issue for the development of scientific software. Some frameworks already offer a number of advanced tools to deal with the complexity related to parallelism in a transparent way. However, all these frameworks often provide only partial answers to the problem as they only deal with hardware complexity and low level numerical complexity like linear algebra. High level complexity related to discretization methods and physical models lack tools to help physicists to develop complex applications. New paradigms for scientific software must be developed to help them to seamlessly handle the different levels of complexity so that they can focus on their specific domain. Generative programming, component engineering and domain-specific languages (either DSL or DSEL) are key technologies to make the development of complex applications easier to physicists, hiding the complexity of numerical methods and low level computer science services. These paradigms allow to write code with a high level expressive language and take advantage of the efficiency of generated code for low level services close to hardware specificities. In the domain of numerical algorithms to solve partial differential equations, their application has been up to now limited to Finite Element (FE) methods, for which a unified mathematical framework has been existing for a long time. Such kinds of DSL have been developed for finite element or Galerkin methods in projects like Freefem++, Getdp, Getfem++, Sundance, Feel++ and Fenics. A new consistent unified mathematical frame has recently emerged and allows a unified description of a large family of lowest-order methods. This framework allows then, as in FE methods, the design of a high level language inspired from the mathematical notation, that could help physicists to implement their application writing the mathematical formulation at a high level. We propose to develop a language based on that frame, embedded in the C++ language. Our work relies on a mathematical framework that enables us to describe a wide family of lowest order methods including multiscale methods based on lowest order methods. We propose a DSEL developed on top of Arcane platform, based on the concepts presented in the unified mathematical frame and on the Feel++ DSEL. The DSEL is implemented with the Boost.Proto library by Niebler, a powerful framework to build a DSEL in C++. We have proposed an extension of the computational framework to multiscale methods and focus on the capability of our approach to handle complex methods.Our approach is extended to the runtime system layer providing an abstract layer that enable our DSEL to generate efficient code for heterogeneous architectures. We validate the design of this layer by benchmarking multiscale methods. This method provides a great amount of independent computations and is therefore the kind of algorithms that can take advantage efficiently of new hybrid hardware technology. Finally we benchmark various complex applications and study the performance results of their implementations with our DSEL

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Appiah, Kwadwo Ampofo. « Microstructural and microanalytical characterization of laminated (C-SiC) matrix composites fabricated by forced-flow thermal-gradient chemical vapor infiltration (FCVI) ». Diss., Georgia Institute of Technology, 2000. http://hdl.handle.net/1853/14910.

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Konečný, Jakub. « Stochastic, distributed and federated optimization for machine learning ». Thesis, University of Edinburgh, 2017. http://hdl.handle.net/1842/31478.

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We study optimization algorithms for the finite sum problems frequently arising in machine learning applications. First, we propose novel variants of stochastic gradient descent with a variance reduction property that enables linear convergence for strongly convex objectives. Second, we study distributed setting, in which the data describing the optimization problem does not fit into a single computing node. In this case, traditional methods are inefficient, as the communication costs inherent in distributed optimization become the bottleneck. We propose a communication-efficient framework which iteratively forms local subproblems that can be solved with arbitrary local optimization algorithms. Finally, we introduce the concept of Federated Optimization/Learning, where we try to solve the machine learning problems without having data stored in any centralized manner. The main motivation comes from industry when handling user-generated data. The current prevalent practice is that companies collect vast amounts of user data and store them in datacenters. An alternative we propose is not to collect the data in first place, and instead occasionally use the computational power of users' devices to solve the very same optimization problems, while alleviating privacy concerns at the same time. In such setting, minimization of communication rounds is the primary goal, and we demonstrate that solving the optimization problems in such circumstances is conceptually tractable.

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Bolognini, Stéphane. « Propriétés mécaniques à haute température de cermets Ti(C,N)-WC-Mo-Co à gradient de composition pour outils de coupe / ». [S.l.] : [s.n.], 2000. http://library.epfl.ch/theses/?display=detail&nr=2161.

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Autzen, Gyde [Verfasser]. « Das globale C*(G,T)-Problem in endlichen Gruppen der lokalen Charakteristik p / Gyde Autzen ». Kiel : Universitätsbibliothek Kiel, 2009. http://d-nb.info/101986754X/34.

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AZEGAMI, Hideyuki, Takahiro IWAI, 秀幸畔上 et 孝広岩井. « 大変形を考慮した接触する弾性体の形状同定 ». 一般社団法人日本機械学会, 2008. http://hdl.handle.net/2237/21119.

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Ramirez, Ivan. « Mathematical Modeling of Immune Responses to Hepatitis C Virus Infection ». Digital Commons @ East Tennessee State University, 2014. https://dc.etsu.edu/etd/2425.

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An existing mathematical model of ordinary differential equations was studied to better understand the interactions between hepatitis C virus (HCV) and the immune system cells in the human body. Three possible qualitative scenarios were explored: dominant CTL response, dominant antibody response, and coexistence. Additionally, a sensitivity analysis was carried out to rank model parameters for each of these scenarios. Therapy was addressed as an optimal control problem. Numerical solutions of optimal controls were computed using a forward-backward sweep scheme for each scenario. Model parameters were estimated using ordinary least squares fitting from longitudinal data (serum HCV RNA measurements) given in reported literature.

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Diefenbach, Maximilian [Verfasser], Dimitrios C. [Akademischer Betreuer] Karampinos, Frederik B. [Gutachter] Laun, Dimitrios C. [Gutachter] Karampinos et Axel [Gutachter] Haase. « Gradient-Echo-Based Multi-Parametric Mapping in Magnetic Resonance Imaging for Measuring Trabecular Bone Density in Osteoporosis / Maximilian Diefenbach ; Gutachter : Frederik B. Laun, Dimitrios C. Karampinos, Axel Haase ; Betreuer : Dimitrios C. Karampinos ». München : Universitätsbibliothek der TU München, 2020. http://d-nb.info/1216626332/34.

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Gratien, Jean-Marc. « A Domain Specific Embedded Language in C++ for lowest-order methods for diffusive problem on general meshes ». Phd thesis, Université de Grenoble, 2013. http://tel.archives-ouvertes.fr/tel-00926232.

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La spécificité des logiciels scientifiques développés par IFP Energies nouvelles tient avant tout à l'originalité des modèles représentant les situations physiques exprimés sous forme de systèmes d'EDPs assortis de lois de fermeture complexes. Le développement de ces logiciels, conçus pour être exécutés sur les super calculateurs parallèles modernes, nécessite de combiner des méthodes volumes finis robustes et efficaces avec des technologies informatiques qui permettent de tirer au mieux parti de ces calculateurs (parallélisme, gestion de la mémoire, réseaux d'interconnexion, etc). Ces technologies de plus en plus sophistiquées ne peuvent plus être maîtrisées dans leur ensemble par les chercheurs métiers chargés d'implémenter des nouveaux modèles. Dans ce rapport nous proposons un langage spécifique aux méthodes de discrétisation Volumes Finis permettant le prototypage rapide de codes industriels ou de recherche. Nous décrivons le cadre mathématique sur lequel nous nous basons ainsi que la mise au point du nouveau langage. Les travaux out été validés sur des problèmes académiques puis par le prototypage d'une application industrielle dans le cadre de l'axe ''CO2 maîtrisé''.

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Sundström, Joakim. « Clostridium difficile – ett växande problem : Om sjuksköterskans arbete för att förebygga spridning av C. difficile i slutenvården ». Thesis, Mittuniversitetet, Avdelningen för omvårdnad, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:miun:diva-20170.

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Aoyama, Taiki, Shota Fukumoto et Hideyuki Azegami. « Shape optimization of continua using NURBS as basis functions ». Springer, 2013. http://hdl.handle.net/2237/21124.

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Rhine, Douglas K. « Theistic perspectives of the mind-brain problem in the writings of John C. Eccles and Donald M. MacKay ». Theological Research Exchange Network (TREN), 1990. http://www.tren.com.

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Lê, Ngoc C. [Verfasser], Ingo [Akademischer Betreuer] Schiermeyer, Ingo [Gutachter] Schiermeyer et Jochen [Gutachter] Harant. « Algorithms for the Maximum Independent Set Problem / Ngoc C. Lê ; Gutachter : Ingo Schiermeyer, Jochen Harant ; Betreuer : Ingo Schiermeyer ». Freiberg : Technische Universitaet Bergakademie Freiberg Universitaetsbibliothek "Georgius Agricola", 2015. http://d-nb.info/1220837970/34.

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Kawagoe, Daisuke. « Regularity of solutions to the stationary transport equation with the incoming boundary data ». Kyoto University, 2018. http://hdl.handle.net/2433/232413.

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Grodzevich, Oleg. « Regularization Using a Parameterized Trust Region Subproblem ». Thesis, University of Waterloo, 2004. http://hdl.handle.net/10012/1159.

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We present a new method for regularization of ill-conditioned problems that extends the traditional trust-region approach. Ill-conditioned problems arise, for example, in image restoration or mathematical processing of medical data, and involve matrices that are very ill-conditioned. The method makes use of the L-curve and L-curve maximum curvature criterion as a strategy recently proposed to find a good regularization parameter. We describe the method and show its application to an image restoration problem. We also provide a MATLAB code for the algorithm. Finally, a comparison to the CGLS approach is given and analyzed, and future research directions are proposed.

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Marko, Kostić. « Konvolucione i distribucione s-polugrupe ». Phd thesis, Univerzitet u Novom Sadu, Prirodno-matematički fakultet u Novom Sadu, 2004. https://www.cris.uns.ac.rs/record.jsf?recordId=73369&source=NDLTD&language=en.

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Ova disertacija se bavi analizom slabo postavljenih apstraktnih Cauchyjevih problema. U prvoj glavi su proučavane konvolucione, ultradistribucione i hiper funkcione polugrupe, njihove medjusobne veze kao i veze sa lokalno integrisanim C-polugrupama. U drugoj glavi su date strukturne osobine C-distribucionih polugrupa, dok su u trećoj glavi dati rezultati vezani za klasu [r]-polugrupa i njihovih primena u teoriji funkcionalnih računa.
U sledećoj glavi je sistematski izložena teorija distribucionih kosinus funkcija, dok se peta glava bavi analizom analitičkih integrisanih polugrupa. Šesta glava je posvećena analizi konvolucionih C-polugrupa i konvolucionih C-kosinus funkcija, dok su u sedmoj glavi prezntovani rezultati vezani za analitičke konvolucione polugrupe, konvolucione kosinus funkcije i njihove veze sa ultradistribucionim i hiperfunkcionim sinusima.

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Mohi, El Din Hatem. « Comparative Analysis of Ant Colony Optimization and Genetic Algorithm in Solving the Traveling Salesman Problem ». Thesis, Blekinge Tekniska Högskola, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-21520.

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Metaheuristics is a term for optimization procedures/algorithms that can be applied to a wide range of problems. These problems for which metaheuristics are used usually fall in the NP-hard category, meaning that they cannot be solved in polynomial time. This means that as the input dataset gets larger the time to solve increases exponentially. One such problem is the traveling salesman problem (TSP) which is and has been widely used as a benchmark problem to test optimization algorithms. This study focused on two such algorithms called ant colony optimization (ACO) and genetic algorithm (GA) respectively. Development of such optimization algorithms can have huge implications in several areas of business and industry. They can for example be used by delivery companies to optimize routing of delivery vehicles as well as in material science/industry where they can be used to calculate the most optimal mix of ingredients to produce materials with the desired characteristics. The approach taken in this study was to compare the performance of the two algorithms in three different programming languages (python, javascript and C#). Previous studies comparing the two algorithms have reported conflicting results where some studies found that ACO yielded better results but was slower than GA, while others found that GA yielded better results than ACO. Results of this study suggested that both ACO and GA could find the benchmark solution, but ACO did so much more consistently. Furthermore javascript was found to be the most efficient language with which to run the algorithms in the setup used in this study.

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Jewanski, Jörg. « Ist C = Rot : eine Kultur-und Wissenschaftsgeschichte zum Problem der wechselseitigen Beziehung zwischen Ton und Farbe von Aristoteles bis Goethe / ». Sinzig : Studio, 1999. http://catalogue.bnf.fr/ark:/12148/cb39996121q.

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Mohebbi, Farzad. « Optimal shape design based on body-fitted grid generation ». Thesis, University of Canterbury. Mechanical Engineering, 2014. http://hdl.handle.net/10092/9427.

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Shape optimization is an important step in many design processes. With the growing use of Computer Aided Engineering in the design chain, it has become very important to develop robust and efficient shape optimization algorithms. The field of Computer Aided Optimal Shape Design has grown substantially over the recent past. In the early days of its development, the method based on small shape perturbation to probe the parameter space and identify an optimal shape was routinely used. This method is nothing but an educated trial and error method. A key development in the pursuit of good shape optimization algorithms has been the advent of the adjoint method to compute the shape sensitivities more formally and efficiently. While undoubtedly, very attractive, this method relies on very sophisticated and advanced mathematical tools which are an impediment to its wider use in the engineering community. It that spirit, it is the purpose of this thesis to propose a new shape optimization algorithm based on more intuitive engineering principles and numerical procedures. In this thesis, the new shape optimization procedure which is proposed is based on the generation of a body-fitted mesh. This process maps the physical domain into a regular computational domain. Based on simple arguments relating to the use of the chain rule in the mapped domain, it is shown that an explicit expression for the shape sensitivity can be derived. This enables the computation of the shape sensitivity in one single solve, a performance analogous to the adjoint method, the current state-of-the art. The discretization is based on the Finite Difference method, a method chosen for its simplicity and ease of implementation. This algorithm is applied to the Laplace equation in the context of heat transfer problems and potential flows. The applicability of the proposed algorithm is demonstrated on a number of benchmark problems which clearly confirm the validity of the sensitivity analysis, the most important aspect of any shape optimization problem. This thesis also explores the relative merits of different minimization algorithms and proposes a technique to “fix” meshes when inverted element arises as part of the optimization process. While the problems treated are still elementary when compared to complex multiphysics engineering problems, the new methodology presented in this thesis could apply in principle to arbitrary Partial Differential Equations.

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Daly, John Louis Jr. « On Comparison of Indentation Models ». Scholar Commons, 2007. http://scholarcommons.usf.edu/etd/3899.

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Thin films that are functionally gradient improve the mechanical properties of film-substrate layered materials. Mechanical properties of such materials are found by using indentation tests. In this study, finite element models are developed to simulate the indentation test. The models are based on an axisymmetric half space of a specimen subjected to spherical indentation. The film layer through the thickness is modeled to have either homogeneous material properties or nonhomogeneous material properties that vary linearly. Maximum indenter displacement, and maximum normal and shear stresses at the interface are compared between the homogeneous model and the nonhomogeneous model for pragmatic contact length to film thickness ratios of 0.2 to 0.4, and film to substrate moduli ratios of 1 to 200 to 1. Additionally, a coefficient is derived from regression of the stress data produced by these models and compared to that used to define the pressure field in the axisymmetric Hertzian contact model. The results of this study suggest that a displacement boundary condition to an indenter produces the same results as a pressure distribution boundary condition. The critical normal stresses that occur between modeling a film as a nonhomogeneous and as a homogeneous material vary from 19% for a modulus ratio of 2.5:1 to as high as 66% for a modulus ratio of 200:1 indicating that the modeling techniques produced very different maximum normal stresses. The difference in the maximum shear stress between the nonhomogeneous and the homogeneous models varied from 19% for a 2.5:1 modulus ratio to 57% for the 200:1 modulus ratio but reached values as low as 6% for the 50:1 modulus ratio. The maximum contact depth between the nonhomogeneous and the homogeneous models varied from 14% for the 2.5:1 case to as much as 75% in the 200:1 case. The results from the reapplication of the pressure field derived from the regression coefficients and the R2 values from these regression models indicate the correctness of the regression model used as well as its ability to replicate the normal stresses in the contact area and maximum indenter displacements in a FEA model for both the homogeneous and the nonhomogeneous models for modulus ratios ranging from 2.5:1 to 200:1. The agreement between the regression based coefficients and the force based coefficients suggests the validity for the use of the theoretical axisymmetric Hertzian contact model for defining the pressure field in the contact area and displacements for both the homogeneous case and the nonhomogeneous case for the considered film to substrate moduli ratios and contact length to film thickness ratios.

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Muna, Izza Hasanul. « Modely a metody pro svozové problému v logistice ». Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2019. http://www.nusl.cz/ntk/nusl-401586.

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The thesis focuses on how to optimize vehicle routes for distributing logistics. This vehicle route optimization is known as a vehicle routing problem (VRP). The VRP has been extended in numerous directions for instance by some variations that can be combined. One of the extension forms of VRP is a capacitated VRP with stochastics demands (CVRPSD), where the vehicle capacity limit has a non-zero probability of being violated on any route. So, a failure to satisfy the amount of demand can appear. A strategy is required for updating the routes in case of such an event. This strategy is called as recourse action in the thesis. The main objective of the research is how to design the model of CVRPSD and find the optimal solution. The EEV (Expected Effective Value) and FCM (Fuzzy C-Means) – TSP (Travelling Salesman Problem) approaches are described and used to solve CVRPSD. Results have confirmed that the EEV approach has given a better performance than FCM-TSP for solving CVRPSD in small instances. But EEV has disadvantage, that the EEV is not capable to solve big instances in an acceptable running time because of complexity of the problem. In the real situation, the FCM –TSP approach is more suitable for implementations than the EEV because the FCM – TSP can find the solution in a shorter time. The disadvantage of this algorithm is that the computational time depends on the number of customers in a cluster.

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Gharabaghi, Sara. « Quantitative Susceptibility Mapping (QSM) Reconstruction from MRI Phase Data ». Wright State University / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=wright1610018553822445.

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Hedin, Josephine, et Enrique Holm. « Annorlunda liv : En C-uppsats om personer med svåra psykiska problem och deras syn på livet i förhållande till utanförskap och återinträde ». Thesis, Stockholms universitet, Institutionen för socialt arbete - Socialhögskolan, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-54447.

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The aim of the essay was to see how the respondents reasoned about different themes like, isolation, integration and barriers to integration, given that they had all been diagnosed with a psychosis diagnosis. The essay takes part of secondary data that had been gathered through interviews by researchers at the department of Research and Development Psychiatric South Stockholm during a 3 year period. To work with the interview data a qualitative interview analysis method was used. The interviews were analyzed against theories of social interaction, labeling, stigma and the theory of ”role exit”. The analysis showed that to be given a psychosis diagnosis is an indicator that one will be isolated from society in terms of work, economy and social relations. A more surprising find of this essay was that even though one is viewed as isolated in terms of the points given above, it does not mean that one necessarily want to strive for a full integration again. One possible interpretation of this find is that one thinks that one is more well off in the current situation than in an integrated situation.

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Koppanooru, Sampat Kumar Reddy. « Estimating Thermal Conductivity and Volumetric Specific Heat of a Functionally Graded Material using Photothermal Radiometry ». Thesis, University of North Texas, 2017. https://digital.library.unt.edu/ark:/67531/metadc1062896/.

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Functionally graded materials (FGMs) are inhomogeneous materials in which the material properties vary with respect to space. Research has been done by scientific community in developing techniques like photothermal radiometry (PTR) to measure the thermal conductivity and volumetric heat capacity of FGMs. One of the problems involved in the technique is to solve the inverse problem, i.e., estimating the thermal properties after the frequency scan has been obtained. The present work involves finding the unknown thermal conductivity and volumetric heat capacity of the FGMs by using finite volume method. By taking the flux entering the sample as periodic and solving the discretized 1-D thermal wave field equation at a frequency domain, one can obtain the complex temperatures at the surface of the sample for each frequency. These complex temperatures when solved for a range of frequencies gives the phase vs frequency scan which can then be compared to original frequency scan obtained from the PTR experiment by using a residual function. Brute force and gradient descent optimization methods have been implemented to estimate the unknown thermal conductivity and volumetric specific heat of the FGMs through minimization of the residual function. In general, the spatial composition profile of the FGMs can be approximated by using a smooth curve. Three functional forms namely Arctangent curve, Hermite curve, and Bezier curve are used in approximating the thermal conductivity and volumetric heat capacity distributions in the FGMs. The use of Hermite and Bezier curves gives the flexibility to control the slope of the curve i.e. the thermal property distribution along the thickness of the sample. Two-layered samples with constant thermal properties and three layered samples in which one of the layer has varying thermal properties with respect to thickness are considered. The program is written in Fortran and several test runs are performed. Results obtained are close to the original thermal property values with some deviation based on the stopping criteria used in the gradient descent algorithm. Calculating the gradients at each iteration takes considerable amount of time and if these gradient values are already available, the problem can be solved at a faster rate. One of the methods is extending automatic differentiation to complex numbers and calculating the gradient values ahead; this is left for future work.

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Oriani, Mattia. « A mixed hybrid finite volumes solver for robust primal and adjoint CFD ». Thesis, Queen Mary, University of London, 2018. http://qmro.qmul.ac.uk/xmlui/handle/123456789/39760.

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In the context of gradient-based numerical optimisation, the adjoint method is an e cient way of computing the gradient of the cost function at a computational cost independent of the number of design parameters, which makes it a captivating option for industrial CFD applications involving costly primal solves. The method is however a ected by instabilities, some of which are inherited from the primal solver, notably if the latter does not fully converge. The present work is an attempt at curbing primal solver limitations with the goal of indirectly alleviating adjoint robustness issues. To that end, a novel discretisation scheme for the steady-state incompressible Navier- Stokes problem is proposed: Mixed Hybrid Finite Volumes (MHFV). The scheme draws inspiration from the family of Mimetic Finite Di erences and Mixed Virtual Elements strategies, rid of some limitations and numerical artefacts typical of classical Finite Volumes which may hinder convergence properties. Derivation of MHFV operators is illustrated and each scheme is validated via manufactured solutions: rst for pure anisotropic di usion problems, then convection-di usion-reaction and nally Navier-Stokes. Traditional and novel Navier-Stokes solution algorithms are also investigated, adapted to MHFV and compared in terms of performance. The attention is then turned to the discrete adjoint Navier-Stokes system, which is assembled in an automated way following the principles of Equational Di erentiation, i.e. the di erentiation of the primal discrete equations themselves rather than the algorithm used to solve them. Practical/computational aspects of the assembly are discussed, then the adjoint gradient is validated and a few solution algorithms for the MHFV adjoint Navier-Stokes are proposed and tested. Finally, two examples of full shape optimisation procedures on internal ow test cases (S-bend and U-bend) are reported.

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Wilmot, Timothy Allen Jr. « Intelligent Controls for a Semi-Active Hydraulic Prosthetic Knee ». Cleveland State University / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=csu1315531357.

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Moffitt, Michael Adam. « Functional Imaging of the Mammalian Spinal Cord ». Case Western Reserve University School of Graduate Studies / OhioLINK, 2004. http://rave.ohiolink.edu/etdc/view?acc_num=case1081363883.

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畔上, 秀幸, Hideyuki Azegami, 志強呉 et Zhi Chang Wu. « 線形弾性問題における領域最適化解析（力法によるアプローチ） ». 日本機械学会, 1994. http://hdl.handle.net/2237/7239.

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AZEGAMI, Hideyuki, et Zhi Chang WU. « Domain Optimization Analysis in Linear Elastic Problems (Approach Using Traction Method) ». 日本機械学会, 1996. http://hdl.handle.net/2237/12156.

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