Tesi sul tema "Problème de torsion"
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1
Zoubairi, Hakima. "Homogénéisation et contrôle optimal pour des problèmes de Stokes et pour un problème de torsion élastique". Metz, 2001. http://tel.ccsd.cnrs.fr/documents/archives0/00/00/12/90/index_fr.html.
Abstract (sommario):
Cette thèse est consacrée à l'étude du contrôle optimal et de l'homogénéisation de quelques problèmes liés à l'équation de Stokes ainsi qu'au problème de torsion élastique. Pour chaque problème étudié, nous imposons un contrôle à l'équation d'état. Ce contrôle appartient à un ensemble appelé « ensemble de contrôles admissibles». On se donne une fonction coût qui dépend à la fois de l'état mais aussi du contrôle. Le contrôle optimal (unique) est la fonction dans l'ensemble de contrôles admissibles qui minimise la fonction coût pour tous les contrôles dans cet ensemble. On étudie alors le comportement limite de celui-ci. S'il admet une limite, on la caractérise si possible, comme étant le contrôle optimal associé au problème limite homogénéisé. Dans la première partie, on se propose d'étudier un problème de contrôle optimal dans un mélange de deux fluides. Ces deux fluides sont répartis périodiquement l'un par rapport à l'autre dans un domaine bi ou tridimensionnel. L'écoulement des deux fluides obéit aux équations de Stokes. Dans la deuxième partie, on s'intéresse encore à un mélange de deux fluides visqueux incompressibles séparés par une interface qui oscille rapidement. Ce problème est régit par les équations de Stockes. Dans la troisième partie, on étudie le contrôle optimal pour les équations de Stockes dans les domaines perforés. On suppose que les perforations sont de taille plus petite qu'une période donnée. Dans la dernière partie, on est amené à étudier le contrôle optimal d'un problème de torsion élastique. Dans chacune de ces parties, on caractérise la limite du contrôle optimal comme étant le contrôle optimal du problème limiteThis thesis is devoted to the study of optimal control and homogeneization for some problems associated to the Stokes equation and also for an elastic torsion problem. For each of the problems, a control act on the state equation. This control belongs to a set of admissible controls. We consider a cost function wich depends on the state and on the control. The control optimal (unique) is the function in the set of admissible controls which minimizes the cost function. Then we study its behaviour. If it admits a limit, we characterize it as an optimal control associated to the homogenized problem. In the first part, we study an optimal control problem in a mixture of two fluids. Those fluids are distributed periodically in a bi or three-dimensionnal domain. Each fluid obeys the Stokes equations. In the second part, we study also a mixture of two fluids but separated by an rapidly oscillating interface. These fluids obeys the Stoke equations. In the third part, we study an optimal control problem for the Stokes equations in perforated domains. We suppose that the size of the perforations is smaller than a given period. In the last part, we study the optimal control of an elastic torsion problem. For each of these parts, we characterize the limit of the optimal control as the optimal control of the limit problem
2
ZOUBAIRI, Hakima. "Homogénéisation et Controle Optimal pour des Problèmes de Stokes et pour un Problème de Torsion Elastique". Phd thesis, Université de Metz, 2001. http://tel.archives-ouvertes.fr/tel-00001290.
Abstract (sommario):
Cette thése est consacrée à l'étude du contrôle optimal et de l'homogénéisation de problèmes liés à l'équation de Stokes ainsi qu'au problème de torsion élastique. Pour chaque problème étudié, nous imposons un contrôle à l'équation d'état. Ce contrôle appartient à un ensemble appelé ``ensemble de contrôles admissibles". On se donne une fonction coût qui dépend à la fois de l'état mais aussi du contrôle. Le contrôle optimal (unique) est la fonction dans l'ensemble de contrôles admissibles qui minimise la fonction coût pour tous les contrôles dans cette ensemble. On étudie alors le comportement limite de celui-ci. S'il admet une limite, on la caractérise si possible, comme étant le contrôle optimal associé au problème limite homogénéisé. Dans un premier temps, on étudie un problème de contrôle optimal dans un mélange de deux fluides. Ces deux fluides sont répartis périodiquement l'un par rapport à l'autre dans un domaine bi ou tridimensionnel. L'écoulement des deux fluides obéit aux équations de Stokes. Par la suite, on s'intéresse encore à un mélange de deux fluides visqueux incompressibles séparés par une interface qui oscille rapidement. Ce problème est régit par les équations de Stokes. Ensuite, on étudie le contrôle optimal pour les équations de Stokes dans les domaines perforés. On suppose que les perforations sont de taille plus petite qu'une période donnée. En dernier lieu, on est amené à étudier le contrôle optimal d'un problème de torsion élastique. Dans chacune de ces parties, on caractérise la limite du contrôle optimal comme étant le contrôle optimal du problème limite.
3
Ait, El Amrani Asmâa. "Homogénéisation d'un problème de torsion élastique pour un arbre cylindrique de section multiconnexe et multiperiodique". Vandoeuvre-les-Nancy, INPL, 2000. http://www.theses.fr/2000INPL074N.
Abstract (sommario):
Les techniques d’homogénéisation « Périodiques », s’appuyant sur les développements asymptotiques de type « Echelle Multiples » et les méthodes variationnelles, sont classiques depuis les années 1970. Cependant, les applications présentent souvent des situations « multipériodiques ». Dans ce mémoire, nous prolongeons les travaux de LEVY – DONATO – SAINT JEAN PAULIN – ALLAIRE et BRIANE, relatifs à l’homogénéisation multipériodique ; nous considérons en fait un cas de conditions de transmission atypiques, à propose du problème de torsion élastique d’un arbre cylindrique de section multiconnexe bipériodique. Nous proposons la solution homogénéisée obtenue par une méthode originale d’échelles multiples. Nous montrons aussi comment dans ce contexte bipériodique, la méthode de l’énergie doit permettre de confirmer le résultat formel obtenu par développements asymptotiques
4
Hammedi, Hiba. "Analyse spectrale des guides d'ondes "twistés"". Thesis, Toulon, 2016. http://www.theses.fr/2016TOUL0001/document.
Abstract (sommario):
Dans cette thèse, nous étudions les propriétés spectrales des guides d'onde quantiques tridimensionnels (les tubes) perturbés. Nous considérons, principalement deux types différents de perturbation : Dans le premier type, il s’agit de la perturbation d’une déformation géométrique. Plus précisément, nous étudions l’opérateur de Laplace de Dirichlet défini dans un tube déformé à l’aide d’une torsion constante perturbée localement par une fonction de même signe (torsion répulsive).Le deuxième type de perturbation consiste à changer localement les conditions aux bords imposées sur la frontière du guide d’onde. En effet, il s’agit de l’étude du Laplacien avec des conditions aux bords mixtes.Nous imposons des conditions aux bords de Dirichlet par tout sur la frontière du guide d’onde, sauf sur une partie bornée où nous considérons des conditions aux bords de Neumann. D’une part, nous examinons les tubes droits (sans déformations géométriques) dans le but de comprendre l’effet de la perturbation des conditions aux bords. D’autre part, nous étudions les tubes torsadés afin d’établir une comparaison entre les effets opposés des deux perturbations (géométrique et des conditions aux bords)In this thesis we study the spectral properties of perturbed 3D quantum waveguides (tubes). We mainly consider two types of perturbation:The first type is a geometric perturbation. More precisely, we study the Laplace operator with Dirichlet boundary conditions defined in a twisted tube. The twist that we consider is a constant one that has been locally perturbed by a function of same sign (a repulsive twist). The second type of perturbation is done by changing locally the boundary conditions. In fact, we study the Laplacian operator with Dirichlet conditions everywhere on the boundary of the tube except on a bounded part where we consider the Neumann conditions. In one hand we study the straight tubes (with no geometric perturbations) to figure out the effect of perturbation that occurred in the boundary conditions. In the other hand we study the twisted tubes to establish a comparison between the opposite effects of these two types of perturbation (the geometric one and the change that we imposed on the boundary conditions)
5
Générau, François. "Sur une approximation variationnelle stable du cut locus, et un problème isopérimetrique non local". Thesis, Université Grenoble Alpes, 2020. http://www.theses.fr/2020GRALM014.
Abstract (sommario):
Cette thèse comporte deux parties. Dans la première partie, nous étudions une généralisation du problème variationnel de torsion élastique-plastique à des variétés. Nous montrons que dans le cas des variétés, le problème n'est pas équivalent à un problème d'obstacle, contrairement au cas euclidien, mais nous établissons l'équivalence lorsque le paramètre du problème tend vers l'infini. Nous montrons, comme dans le cas euclidien, que l'ensemble de non contact contient le cut locus de la variété, et converge vers ce dernier au sens de Hausforff. Nous montrons de plus que les miniseurs du problème sont uniformément semiconcaves. Nous en déduisons une approximation stable de cut locus, dans l'esprit du lambda axe médian de Chazal et Lieutier. Nous utilisons ensuite ce résultat pour calculer numériquement le cut locus de surfaces de géométries variées.Dans la seconde partie, nous étudions une extension d'un problème isopérimétrique non local. Précisément, on adjoint un potentiel de confinement au modèle de goutte liquide du noyau de Gamow. Nous étudions alors les minimiseurs de grand volume. Nous montrons que pour certains jeux de paramètres, les minimiseurs de grand volume convergent vers des boules, voire sont exactement des boules. Nous développons ensuite une méthode numérique pour ce problème variationnel. Cela permet de confirmer numériquement une conjecture de Choksi et Peletier en dimension 2 : dans ce cas les minimiseurs du modèle de Gamow semble être des boules si ils existentThis thesis is composed of two parts. In the first part, we study a generalization of the variational problem of elastic-plastic torsion problem to manifolds. We show that in the case of manifolds, the problem is not equivalent to an obstacle type problem, contrary to the euclidean case, but we establish the equivalence when the parameter of the problem goes to infinity. We show, as in the euclidean case, that the non contact set contains the cut locus of the manifold, and converges to the latter in the Hausdorff sense. What is more, we show that the minimizers of the problem are uniformly semiconcave. We deduce a stable approximation of the cut locus, in the spirit of the lambda medial axis of Chazal and Lieutier. We then use this result to compute numerically the cut locus of some surfaces of varied geometries.In the second part, we study an extension of a nonlocal isoperimetric problem. More precisely, we add a confinement potential to Gamow's liquid drop model for the nucleus. We then study large volume minimizers. We show that for certain sets of parameters, large volume minimizers converge to the ball, or may even exactly be the ball. Moreover, we develop a numerical method for this variational problem. Our results confirm numerically a conjecture of Choksi and Peletier, in dimension 2: it seems that minimizers of Gamow'sliquid drop model are balls as long as they exist
6
Perin, Chloé. "Plongements élémentaires dans un groupe hyperbolique sans torsion". Phd thesis, Université de Caen, 2008. http://tel.archives-ouvertes.fr/tel-00460330.
Abstract (sommario):
L'objet de cette thèse est d'obtenir une description des plongements élémentaires (au sens de la logique du premier ordre) dans un groupe hyperbolique sans torsion. Le résultat principal décrit ces plongements en terme d'une structure définie par Sela dans sa solution au problème de Tarski: la structure de tour hyperbolique. Ainsi, si H est plongé élementairement dans un groupe hyperbolique sans torsion G, on peut obtenir G en amalgamant successivement des groupes de surfaces à bord à un produit libre de H avec des groupes libres et des groupes de surfaces sans bord. Ceci permet en corollaire de montrer qu'un sous-groupe plongé élémentairement dans un groupe libre de type fini est un facteur libre. Les techniques utilisées pour obtenir cette description sont essentiellement géométriques: actions sur des arbres réels ou simpliciaux, existence de décompositions JSJ. On s'appuie également sur des résultats d'existence d'ensembles de factorisation qui affirment que pour certains groupes A de type fini, étant donné un groupe hyperbolique sans torsion G, il existe un ensemble fini de quotients de A tel que tout morphisme non injectif de A vers G se factorise par l'un de ces quotients après précomposition par un automorphisme de A. On expose une preuve de ces résultats, y compris une version complète et détaillée du shortening argument de Rips et Sela. Le shortening argument montre, grâce à l'analyse de Rips des actions sur des arbres réels, que si une suite d'action d'un groupe A sur des espaces hyperboliques converge vers un A-arbre réel d'un certain type, alors une infinité de ces actions peuvent être raccourcies.
7
Graff, Emmanuel. ""Link-homotopy" in low dimensional topology". Electronic Thesis or Diss., Normandie, 2023. http://www.theses.fr/2023NORMC244.
Abstract (sommario):
Ce mémoire explore la topologie de basse dimension, en mettant l'accent sur la théorie des nœuds. Une théorie consacrée à l'étude des nœuds tels qu'ils sont communément compris : des morceaux de ficelle enroulés dans l'espace ou, de manière plus générale, des entrelacs formés en prenant plusieurs bouts de ficelle. Les nœuds et les entrelacs sont étudiés à déformation près, par exemple, à isotopie près, ce qui implique des manipulations sans couper ni faire passer la ficelle à travers elle-même. Cette thèse explore la link-homotopie, une relation d'équivalence plus souple où des composantes distinctes demeurent séparées, mais où une composante donnée peut s'auto-intersecter. La théorie des claspers, des puissants outils de chirurgie, est développée à link-homotopie près. Leur utilisation permet une démonstration géométrique de la classification des entrelacs avec 4 composantes ou moins à link-homotopie près. Une attention particulière est ensuite accordée aux tresses, des objets mathématiques apparentés aux nœuds et aux entrelacs. Il est montré que le groupe de tresses homotopiques est linéaire, c'est-à-dire isomorphe à un sous-groupe de matrices. De nouvelles présentations de ce groupe sont également proposées. Enfin, il est établi que le groupe de tresse homotopique est sans torsion, quel que soit le nombre de composantes. Ce dernier résultat s'appuie sur le contexte plus large de la théorie des nœuds soudésThis thesis explores low-dimensional topology, with a focus on knot theory. Knot theory is dedicated to the study of knots as commonly understood: a piece of string tied in space or, more generally, links formed by taking several pieces of string. Knots and links are studied up to deformation, for example, up to isotopy, which involves manipulations that do not require cutting or passing the string through itself. This thesis explores link-homotopy, a more flexible equivalence relation where distinct components remain disjoint, but a single component can self-intersect. The theory of claspers, powerful tools of surgery, is developed up to link-homotopy. Their use allows for a geometric proof of the classification of links with 4 components or less up to link-homotopy. Special attention is then given to braids, mathematical objects related to knots and links. It is shown that the homotopy braid group is linear, meaning it is faithfully represented by a subgroup of matrices. New group presentations are also proposed. Finally, it is established that the homotopy braid group is torsion-free for any number of components. This last result draws upon the broader context of welded knot theory
8
Finski, Siarhei. "On some problems of holomorphic analytic torsion". Thesis, Sorbonne Paris Cité, 2019. https://theses.md.univ-paris-diderot.fr/FINSKI_Siarhei_va.pdf.
Abstract (sommario):
Le but de cette thèse est d'étudier la torsion analytique dans deux contextes différents. Dans le premier contexte, on étudie l'asymptotique de la torsion analytique, quand un fibré vectoriel holomorphe hermitien est tordué par une puissance croissant du fibré en droites positif. Dans le deuxième contexte, on généralise la théorie de la torsion analytique pour des surfaces de Riemann avec des pointes hyperboliques. Motivé par des singularités de la métrique complète de courbure scalaire constante -1 sur des surfaces de Riemann stables épointées, on demande que la métrique sur la surface de Riemann soit lisse seulement en dehors d'un nombre fini des points au voisinage auxquelles elle peut avoir des singularités comme la métrique de Poincaré sur un disque épointé. On fixe un fibré vectoriel holomorphe hermitien qui peut avoir au pire des singularités logarithmiques au voisinage des points marqués. Pour ces données, en renormalisant la trace de l'opérateur de la chaleur, on construit la torsion analytique et on étudie ces propriétésIn the first context, we study the asymptotics of the analytic torsion, when a Hermitian holomorphic vector bundle is twisted by an increasing power of a positive line bundle. In the second context, we generalize the theory of analytic torsion for surfaces with hyperbolic cusps. Motivated by singularities appearing in complete metrics of constant scalar curvature -1 on stable Riemann surfaces, we suppose that the metric on the surface is smooth outside a finite number points in the neighborhood of which it can to have singularities like Poincaré metric has on a punctured disc. We fix a Hermitian holomorphic vector bundle which has at worst logarithmic singularities in the neighborhood of the marked points. For these data, by renormalizing the trace of the heat operator, we construct the analytic torsion and study its properties. Then we study the properties of the analytic torsion in family setting: we prove the curvature theorem, we study the behavior of the analytic torsion when the cusps are created by degeneration and we give some applications to the moduli spaces of pointed curves
9
Bury, A. S. "Torsional vibration problems in reciprocating machinery". Thesis, Сумський державний університет, 2014. http://essuir.sumdu.edu.ua/handle/123456789/34851.
Abstract (sommario):
Torsional vibration can be broadly described as the angular vibration of any object as a result of applied torque. Torsional vibration involves the twisting of shafts while the machinery is rotating.
When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/34851
10
Zoubairi, Hakima Alabau Fatiha. "Homogénéisation et contrôle optimal pour des problèmes de stokes et pour un problème de torsion élastique". [S.l.] : [s.n.], 2001. http://tel.ccsd.cnrs.fr/documents/archives0/00/00/12/90/index_fr.html.
11
Zine, Abidine Ouazzani Ali. "Prise en compte de cavites dans des problemes aux limites elliptiques : application a la torsion elastique". Paris 6, 1986. http://www.theses.fr/1986PA066584.
Abstract (sommario):
On etudie dans ce travail la structure des solutions de problemes aux limites dans des domaines comportant une cavite asymptotiquement petite. Pour cela, on utilise des methodes asymptotiques qui nous permettent de faire une etude a deux echelles (un echelle macroscopique et une echelle microscopique) des effets de ce type de singularite. Enfin, les resultats obtenus seront appliques au probleme de la torsion d'arbres perces
12
Martinez, Metzmeier César. "Two problems in arithmetic geometry. Explicit Manin-Mumford, and arithmetic Bernstein-Kusnirenko". Thesis, Normandie, 2017. http://www.theses.fr/2017NORMC224/document.
Abstract (sommario):
Dans la première partie de cette thèse, on présente des bornes supérieures fines pour le nombre de sous-variétés irréductibles de torsion maximales dans une sous-variété du tore complexe algébrique $(\mathbb{C}^{\times})^n$ et d'une variété abélienne. Dans les deux cas, on donne une borne explicite en termes du degré des polynômes définissants et la variété ambiante. De plus, la dépendance en le degré des polynômes est optimale. Dans le cas du tore complexe, on donne aussi une borne explicite en termes du degré torique de la sous-variété. En conséquence de ce dernier résultat, on démontre les conjectures de Ruppert, et Aliev et Smyth pour le nombre de points de torsion isolés dans une hypersurface. Ces conjectures bornent ce nombre en terme, respectivement, du multi-degré et du volume du polytope de Newton d'un polynôme définissant l'hypersurface.Dans la deuxième partie de cette thèse, on présente une borne supérieure pour la hauteur des zéros isolés, dans le tore, d'un système de polynômes de Laurent sur un corps adélique qui satisfait la formule du produit. Cette borne s'exprime en termes des intégrales mixtes des fonctions toit locales associées à la hauteur choisie et le système des polynômes de Laurent. On montre aussi que cette borne est presque optimale dans quelques familles d'exemples. Ce résultat est un analogue arithmétique du théorème de Bern\v{s}tein-Ku\v{s}nirenkoIn the first part of this thesis we present sharp bounds on the number of maximal torsion cosets in a subvariety of a complex algebraic torus $(\mathbb{C}^{\times})^n$ and of an Abelian variety. In both cases, we give an explicit bound in terms of the degree of the defining polynomials and the ambient variety. Moreover, the dependence on the degree of the polynomials is sharp. In the case of the complex torus, we also give an effective bound in terms of the toric degree of the subvariety. As a consequence of the latter result, we prove the conjectures of Ruppert, and Aliev and Smyth on the number of isolated torsion points of a hypersurface. These conjectures bound this number in terms of the multidegree and the volume of the Newton polytope of a polynomial defining the hypersurface, respectively.In the second part of the thesis, we present an upper bound for the height of isolated zeros, in the torus, of a system of Laurent polynomials over an adelic field satisfying the product formula. This upper bound is expressed in terms of the mixed integrals of the local roof functions associated to the chosen height function and to the system of Laurent polynomials. We also show that this bound is close to optimal in some families of examples. This result is an arithmetic analogue of the classical Bern\v{s}tein-Ku\v{s}nirenko theorem
13
Heffernan, Rhys. "Addressing One-Dimensional Protein Structure Prediction Problems with Machine Learning Techniques". Thesis, Griffith University, 2018. http://hdl.handle.net/10072/381401.
Abstract (sommario):
In this thesis we tackle the protein structure prediction subproblems listed previously, by
applying state of the art deep learning techniques.
The work in chapter 2 presents the method SPIDER. In this method, state of the art
deep learning is applied iteratively to the task of predicting backbone torsion angles and
, and dihedral angles and , by applying evolutionary-derived sequence pro les and
physio-chemical properties of amino acid residues. This work is the fi rst method for the
sequence based prediction of and angles.
Chapter 3 presents the method SPIDER2. This method takes the state of the art
iterative deep learning applied in SPIDER, and extends it to the prediction of three-state
secondary structure, solvent accessible surface area, and ; ; , and angles, and achieves
the best reported prediction accuracies for all of them (at the date of publication).
Chapter 4 further builds on the work done in the previous chapters, and now adds
the prediction of half sphere exposure (both C and C based) and contact numbers to
SPIDER2, in a method called SPIDER2-HSE.
In Chapter 5, Long Short-Term Memory Bidirectional Recurrent Neural Networks were
applied to the prediction of three-state secondary structure, solvent accessible surface area,
; ; , and angles, as well as half sphere exposure and contact numbers. Previously
methods used for these predictions (including SPIDER2) were typically window based.
That is to say that the input data made available to the model for a given residue, is
comprised of information for only that residue and a number of residues on either side in the sequence (in the range of 10-20 residues on each side). The use of LSTM-BRNNs in
this method allows SPIDER3 to better learn both long and short term interactions within
proteins. This advancement again lead to the best reported accuracies for all predicted
structural properties.
In Chapter 6, the LSTM-BRNN model used in SPIDER3 is applied to the prediction
of the same structural property predictions, plus the prediction of eight-state secondary
structure, using only single-sequence inputs. That is, structural properties were predicted
without using any evolutionary information. This provides a method that provides not
only the best reported single-sequence secondary structure and solvent accessible surface
area predictions, but the fi rst reported method for the single-sequence based prediction of
half sphere exposure, contact numbers, and ; ; , and angles. This study is important
as most proteins have few homologous sequences and their evolutionary profi les are inac-
curate and time-consuming to calculate. This single-sequence-based technique allows for
fast genome-scale screening analysis of protein one-dimensional structural properties.Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
School of Eng & Built Env
Science, Environment, Engineering and Technology
Full Text
14
Kleiss, Torsten [Verfasser], e Hans Wilhelm [Akademischer Betreuer] Alfen. "Institutional Arrangements for Municipal Solid Waste Combustion Projects / Torsten Kleiss ; Betreuer: Hans Wilhelm Alfen". Weimar : Professur Betriebswirtschaftslehre im Bauwesen, 2008. http://d-nb.info/1116609460/34.
15
Czekajski, Casimir. "Application de la méthode des équations intégrales sur la frontière à certains types de problèmes rencontrés en mécanique des structures". Toulouse, ENSAE, 1985. http://www.theses.fr/1985ESAE0008.
16
Speer, Arne Verfasser], Tanja [Akademischer Betreuer] [Kessel e Torsten [Akademischer Betreuer] Böger. "Entwicklung von Key Performance Indikatoren auf dem Weg vom Erhaltungsmanagement zum Asset Management für Bundesautobahnen / Arne Speer ; Tanja Kessel, Torsten Böger". Braunschweig : Technische Universität Braunschweig, 2019. http://d-nb.info/1181946158/34.
17
Speer, Arne [Verfasser], Tanja [Akademischer Betreuer] Kessel e Torsten [Akademischer Betreuer] Böger. "Entwicklung von Key Performance Indikatoren auf dem Weg vom Erhaltungsmanagement zum Asset Management für Bundesautobahnen / Arne Speer ; Tanja Kessel, Torsten Böger". Braunschweig : Technische Universität Braunschweig, 2019. http://d-nb.info/1181946158/34.
18
Tomanek, Dagmar P. [Verfasser], e Torsten [Akademischer Betreuer] Eymann. "Möglichkeiten und Grenzen der Wertschöpfungsoptimierung von medizinischen Dienstleistungen mithilfe der Wertstromorientierung am Beispiel von klinischen Prozessen. / Dagmar P. Tomanek ; Betreuer: Torsten Eymann". Bayreuth : Universität Bayreuth, 2018. http://d-nb.info/1159632898/34.
19
Kushnarov, Andriy. "Numerical Method For Conform Reflection". Master's thesis, METU, 2010. http://etd.lib.metu.edu.tr/upload/2/12611426/index.pdf.
Abstract (sommario):
Conformal map has application in a lot of areas of science, e.g., fluid flow, heat conduction,
solidification, electromagnetic, etc. Especially conformal map applied to elasticity theory can
provide most simple and useful solution. But finding of conformal map for custom domain
is not trivial problem. We used a numerical method for building a conformal map to solve
torsion problem. In addition it was considered an infinite system method to solve the same
problem. Results are compared.
20
Ziebertz, Torsten [Verfasser], Christine [Akademischer Betreuer] Schwarzer e Eckard [Akademischer Betreuer] König. "Theoretische Annahmen personzentrierter Beraterinnen und Berater, die mit Familien arbeiten : eine qualitative Studie / Torsten Ziebertz. Gutachter: Christine Schwarzer ; Eckard König". Düsseldorf : Universitäts- und Landesbibliothek der Heinrich-Heine-Universität Düsseldorf, 2011. http://d-nb.info/1015363261/34.
21
Silva, Henrique Furia. "Formulação do problema da torção uniforme em barras de seção transversal maciça". Universidade de São Paulo, 2005. http://www.teses.usp.br/teses/disponiveis/3/3144/tde-20022006-150915/.
Abstract (sommario):
O escopo do trabalho é estudar o problema da torção uniforme em barras de seção maciça e resolvê-lo analiticamente para obter o momento de inércia à torção da seção transversal e os deslocamentos ao longo de toda a barra. Este trabalho foi desenvolvido no contexto da Teoria da Elasticidade, utilizando o método semi-inverso para determinar as equações de Saint-Venant para a torção uniforme. As seções em forma de elipse e triângulo eqüilátero foram resolvidas utilizando a função de tensão de Prandtl, a função empenamento e a sua conjugada harmônica. A seção retangular foi resolvida utilizando as funções empenamento e de Prandtl desenvolvidas em séries infinitas. Foi desenvolvida uma formulação matricial utilizando o Método de Galerkin para resolver problemas que não possuem solução fechada.The main purpose of this essay is to present the issue of the uniform torsion in solid section bars and to solve it analytically to achieve the moment of inertia to the torsion of the transversal section and the displacements throughout the whole bar. This essay was developed in the Elasticity Theory context, using the semi-inverse method to determine the Saint-Venant equations to the uniform torsion. The sections in ellipse and equilateral triangle were solved using the Prandtl stress function, the warping function and its harmonic conjugate. The rectangular section was solved using the warping and the Prandtl functions developed in infinite series. A formulation based on matrixes was developed using the Galerkin method to solve problems that do not have closed solution.
22
Alles, Torsten [Verfasser]. "Anforderungsorientierte Rehabilitation zur Förderung der Teilhabe am Arbeitsleben durch Einsatz von Assessment : eine kontrollierte Interventionsstudie im Rahmen der stationären Rehabilitation von Rückenleiden / Torsten Alles". Köln : Zentralbibliothek der Deutschen Sporthochschule, 2007. http://d-nb.info/1103050230/34.
23
Yamamoto, Taira. "Nonlinear finite element analysis of transverse shear and torsional problems in reinforced concrete shells". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0002/MQ45940.pdf.
24
Rioux, Myriam. "Numerical Computations of Action Potentials for the Heart-torso Coupling Problem". Thèse, Université d'Ottawa / University of Ottawa, 2012. http://hdl.handle.net/10393/20533.
Abstract (sommario):
The work developed in this thesis focusses on the electrical activity of the heart, from the modeling of the action potential originating from cardiac cells and propagating through the heart, as well as its electrical manifestation at the body surface. The study is divided in two main parts: modeling the action potential, and numerical simulations.
For modeling the action potential a dimensional and asymptotic analysis is done. The key advance in this part of the work is that this analysis gives the steps to reliably control the action potential. It allows predicting the time/space scales and speed of any action potential that is to say the shape of the action potential and its propagation. This can be done as the explicit relations on all the physiological constants are defined precisely. This method facilitates the integrative modeling of a complete human heart with tissue-specific ionic models. It even proves that using a single model for the cardiac action potential is enough in many situations.
For efficient numerical simulations, a numerical method for solving the heart-torso coupling problem is explored according to a level set description of the domains. This is done in the perspective of using directly medical images for building computational domains. A finite element method is then developed to manage meshes not adapted to internal interfaces. Finally, an anisotropic adaptive remeshing methods for unstructured finite element meshes is used to efficiently capture propagating action potentials within complex, realistic two dimensional geometries.
25
Diesel, Torsten [Verfasser], Marin [Akademischer Betreuer] Trenk, Marin [Gutachter] Trenk e Iris [Gutachter] Gareis. ""7 people and a mayor": westernized communities, social change and violence among the Inuit of Nunavut : volumes 1 and 2 / Torsten Diesel ; Gutachter: Marin Trenk, Iris Gareis ; Betreuer: Marin Trenk". Frankfurt am Main : Universitätsbibliothek Johann Christian Senckenberg, 2019. http://d-nb.info/1195601581/34.
26
Krüger, Torsten [Verfasser]. "Die Auswirkungen des Waldsterbens und der Einfluß weiterer Faktoren auf die Populationsschwankungen des Birkhuhnes (Tetrao tetrix L.) im sächsischen Erzgebirge auf Grundlage einer Luftbildanalyse / Torsten Krüger". Aachen : Shaker, 2004. http://d-nb.info/1170531407/34.
27
Pollok, Patrick [Verfasser], Frank Thomas [Akademischer Betreuer] Piller e Torsten Oliver [Akademischer Betreuer] Salge. "Three Essays on Crowdsourcing for Technical Problem Solving / Patrick Pollok ; Frank Thomas Piller, Torsten Oliver Salge". Aachen : Universitätsbibliothek der RWTH Aachen, 2017. http://d-nb.info/116794478X/34.
28
Bohonak, Noni McCullough. "Finding a Fitness Function to be Used with Genetic Algorithms to Solve a Protein Folding Problem: The ab initio Prediction of a Protein Using Torsion Angles". NSUWorks, 2000. http://nsuworks.nova.edu/gscis_etd/418.
Abstract (sommario):
This dissertation shows that the ab initio prediction of a protein using torsion angles will work using the correct fitness function. It shows that work can be done on a high-end workstation using a small model of a protein. It was based on the previous work of Dr. Steffen Schulze-Kremer who received limited success with a faculty fitness function and a massively parallel system. The purpose of this work was to not only find the solution but to demonstrate how our rapidly advancing technology will permit this type of research to be moved from the costly parallel systems, nuclear magnetic resonance, and x-ray crystallography to a less costly microcomputer system. In order to accomplish this, the code was run with Microsoft's Visual C++ (version 6) on Intel systems running at 220 MHz, 550 MHz, and 700 MHz with 40 MB, 512 MB, and 256 MB of memory. The results of this work will pave the way for further research in this area on less costly hardware.
29
Pešek, Ondřej. "Stabilitní problémy prutů z vrstveného konstrukčního skla". Doctoral thesis, Vysoké učení technické v Brně. Fakulta stavební, 2018. http://www.nusl.cz/ntk/nusl-390277.
Abstract (sommario):
Transparent and subtle structures are features of modern architecture. Structural glass is constructional material that provides to realize architect's visions and ideas. Glass as a constructional material is more often used as a material for primary load-bearing structures. Realization of safe, reliable and economic glass structure is real challenge for structural engineers because of absence of standards for designing of glass members and elements. Compressed members (columns), bended members (beams) and members loaded by compression and bending (beam-columns) were analysed in the frame of the doctoral thesis whereby the emphasis is being placed on the lack of stability – flexural buckling, lateral-torsional buckling and flexural-lateral-torsional buckling. Measuring of shape and amplitude of initial geometrical imperfections is a part of doctoral thesis. The theoretical analysis describes the behaviour of the member by means of solving the differential equations. The solution according to the second order theory developed for metal members is applied on structural laminated glass members with use of effective cross-sectional characteristics. Numerical analysis is focused on the use of commonly available software based on finite element method in order to predict the load-bearing resistance of laminated glass members. Actual behaviour of laminated and monolithic structural glass members was found within experimental program. The correctness of FEM model and analytical solutions were evaluated by comparing with test results. The goal of the doctoral thesis was determine of buckling curves for calculation of flexural buckling and lateral-torsional buckling resistances by the same calculation procedure as for metal members. Because of small number of experimentally tested specimens the Monte Carlo simulation was performed.
30
Valeš, Jan. "Citlivostní analýza stabilitních problémů ocelových konstrukcí". Doctoral thesis, Vysoké učení technické v Brně. Fakulta stavební, 2018. http://www.nusl.cz/ntk/nusl-390286.
Abstract (sommario):
The doctoral thesis is focused on evaluation of global sensitivity analysis of load-carrying capacity of steel hot-rolled beams. These beams are subjected to lateral-torsional buckling, weak axis buckling and strong axis buckling. Very comprehensive computational models which were both geometrically and materially nonlinear were created in Ansys software using solid finite elements to calculate the load-carrying capacity. The computational models allowed modelling of random initial imperfections such as initial curvature, deviations of cross-section dimensions and steel properties. Sensitivity analysis quantified their influence on the load-carrying capacity. Simulation runs of random imperfections were generated using the Latin Hypercube Sampling method. Since the evaluation of sensitivity analysis of load-carrying capacity of all finite element models would cost an extreme amount of computer time, the thesis aimed at developing a meta-model (also known as surrogate model) based on approximation of FEM model. The approximation polynomial then facilitated the evaluation of sensitivity indices using a high number of simulation runs. At the end, the relationships between the slenderness and the first and second-order sensitivity indices are plotted in graphs. Those random input imperfections that influence the variability of load-carrying capacity the most are pointed out.
31
Hecher, Markus [Verfasser], Stefan [Akademischer Betreuer] Woltran, Torsten [Akademischer Betreuer] Schaub, Mirosław [Gutachter] Truszczynski e Heribert [Gutachter] Vollmer. "Advanced tools and methods for treewidth-based problem solving / Markus Hecher ; Gutachter: Mirosław Truszczynski, Heribert Vollmer ; Stefan Woltran, Torsten Schaub". Potsdam : Universität Potsdam, 2021. http://d-nb.info/1238686745/34.
32
BEZZICCHERI, MATTEO. "Problems in measurement of mechanical loads in wind turbines: bending/torsional moments by strain gage bridges and torque by optical transducer". Doctoral thesis, Università Politecnica delle Marche, 2018. http://hdl.handle.net/11566/252847.
Abstract (sommario):
Il lavoro tratta la complessità di misurare carichi meccanici su grandi turbine eoliche; parametri cruciali per la certificazione e il monitoraggio delle condizioni di funzionamento.
I carichi meccanici di maggior rilievo su una turbina eolica sono i momenti flettenti e torcenti che, in accordo con la normativa IEC 61400‐13, è consigliabile misurare attraverso ponti estensimetrici interi.
Questa tesi discute le linee guida per la progettazione della catena di misura estensimetrica e confronta le diverse possibili procedure di calibrazione: analitica, carichi esterni e squilibri propri. Il lavoro propone modelli di calibrazione che sfruttano squilibri di massa propri, commenta gli intervalli di calibrazione raggiungibili e presenta un’analisi di incertezza del processo di calibrazione.
La calibrazione dovrebbe avvenire in condizione isotermiche ma nella pratica questo requisito potrebbe non essere sempre verificato. Pertanto, la tesi esamina l’influenza del fenomeno termico sulla misura estensimetrica e le soluzioni tecniche adottabili per limitare il fenomeno.
Tra le misure estensimetriche, quella della coppia sull’albero è la più incerta. Tuttavia, studi dimostrano che il segnale di coppia fornisce informazioni sullo stato di salute della macchina quindi è necessario usare soluzioni più precise, come i torsiometri in linea, che risultano però essere invasive e inadeguate. L’alternativa viene proposta nella seconda parte della tesi, ovvero una tecnica di misura della coppia innovativa e senza contatto costituita da due nastri zebrati montati sull’albero e da due sonde ottiche su un supporto rigido non rotante.
Le prestazioni del sistema sono state analizzate in un banco prova. I risultati mostrano una buona corrispondenza con le misure di riferimento eseguite attraverso un torsiometro in linea con una incertezza del ± 0,3%. Infine, la tesi presenta un’analisi di fattibilità per due soluzioni reali di turbine eoliche e mostra come la tecnica di misura è meno incerta quando applicata su alberi lunghi e lenti.This thesis discusses the complexity of measuring mechanical loads on large wind turbines; parameters that play a crucial role in the certification and monitoring of wind turbines. The most important mechanical loads on a wind turbine are bending and torsional moments that are usually measured through full strain gage bridges, as recommended by the standard IEC 61400-13. This thesis discusses the guidelines to design the strain gage measurement chain and a comparison among the different calibration procedures: analytical, external loads and gravity. This work proposes static-dynamic models for a gravity calibration, comments on the attainable range of calibration and presents an uncertainty analysis of the calibration process. Even if measurement should take place in isothermal condition, this is not always the case in real world practice. Therefore, the thesis puts into evidence its influence on calibration and signal uncertainty and the technical solutions that can be adopted to limit the phenomenon. Among the strain gage measurements, the torque measurement on the shaft is the most uncertain. However, many studies have shown that an accurate torque measurement can provide much information about the WT’s health. Available solutions more accurate, like inline torque sensor, are invasive and inappropriate. This thesis, in its second part, analyses a novel, contactless torque measurement system consisting of two shaft-mounted zebra tapes and two optical sensors mounted on stationary rigid supports. The performance of the system has been analysed experimentally on a test bench. The results show good agreement with reference measurements from an in-line, invasive torque transducer with an uncertainty of ±0.3%. Finally, a feasibility analysis and a system scale-up design for two typical WTs with different shaft configurations has been performed and shows that the measurement technique is less uncertain when performed on long and slow shafts.
33
Luna, Collazos Juan Arturo. "Análisis sísmico y diseño estructural de un edificio de concreto armado en esquina de cuatro pisos y un semisótano con problema torsional". Bachelor's thesis, Universidad Peruana de Ciencias Aplicadas (UPC), 2020. http://hdl.handle.net/10757/648681.
Abstract (sommario):
En la presente tesis se analiza el problema torsional extremo de un edificio en esquina de cuatro pisos y un semisótano. Los edificios en esquinas comúnmente presentan un diseño arquitectónico comercial, que aprovecha el perímetro colindante con la calle para poner ventanas y mamparas. Sin embargo, este diseño arquitectónico no toma en cuenta irregularidades estructurales. Una de las irregularidades es la torsional. La torsión es consecuencia de las excentricidades entre el Centro de Masa (CM) y el Centro de Rigidez (CR) en ambos ejes. Para la presente tesis se plantea la siguiente hipótesis: “El caso en estudio presenta irregularidad torsional extrema dada su arquitectura y su ubicación en esquina. Esta irregularidad no está permitida según Norma en Edificaciones categoría “C” y con zonificación 4, por lo que se deberá aumentar la rigidez en zonas críticas. Esta rigidez no depende del incremento de gran longitud de placas sino de su espesor y su ubicación dentro de la estructuración, para su demostración se proponen cinco modelos que se analizan sísmicamente empleando la Norma Técnica E030-2016 teniendo como punto de partida, los planos de arquitectura y una estructuración base; para luego escoger uno de los cinco modelos y realizar el correspondiente diseño estructural de todos los elementos de la edificación”. Además, la tesis tiene como valor añadido el análisis torsional bajo tres normas técnicas de Sismoresistencia de los años 2003, 2016 y 2018, con el objetivo de encontrar diferencias sustanciales entre ellas. Además, se plantea realizar el respectivo análisis Tiempo-Historia del modelo solución.In this thesis the extreme torsional problem of a four-story corner building and a basement is analyzed. The buildings in controlled corners have a commercial architectural design, which takes advantage of the perimeter adjacent to the street to put windows and screens. However, this architectural design does not take into account structural irregularities. One of the irregularities is the torsional one. The torsion is a consequence of the eccentricities between the Mass Center (CM) and the Rigidity Center (CR) in both axes. For the present thesis, the following hypothesis is proposed: “The case under study presents extreme torsional irregularity given its architecture and its corner location. This irregularity is not allowed according to Standard in Buildings category "C" and with zoning 4, so the rigidity in critical areas will be increased. This rigidity does not depend on the increase of large length of plates but on its thickness and its location within the structuring For its demonstration, five models are proposed, which are analyzed seismically using Technical Standard E030-2016, taking as a starting point the architectural plans and a basic structuring; then choose one of the five models and make the corresponding structural design of all the elements of the building”. In addition, the thesis has as an added value the torsional analysis under three technical standards of earthquake resistance of the years 2003, 2016 and 2018, with the objective of finding substantial differences between them. In addition, it is proposed to perform the respectful Time-History analysis of the solution model.
Tesis
34
Garami, Boris. "Dynamický model harmonické převodovky". Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2016. http://www.nusl.cz/ntk/nusl-254390.
Abstract (sommario):
This thesis deals with the design of a dynamic model of a harmonic drive. It includes a theoretical study aimed at the analysis of the harmonic drive gearing principle and its nonlinear properties. The first part of the practical section deals with the analytical calculation of the nondeformed geometry of the Flexspline. Based on these results, several simulations in ANSYS are created to identify torsional characteristics of a harmonic drive. These simulation models are further enhanced by the analysis of clearance, backlash and inaccuracies and their impact on torsional properties. By using MATLAB /Simulink, several dynamic submodels are created representing the individual characteristics of nonlinearities in harmonic drives. Furthermore, a comprehensive dynamic model is created of the mechatronic system which is describing all nonlinearities and kinematic error of the transmission. The dynamic model is also experimentally verified based on its damping properties.
35
Kurt, Arda. "Boundary Element Method Formulation And Its Solution In Forward Problem Of Electrocardiography By Using A Realistic Torso Model". Master's thesis, METU, 2006. http://etd.lib.metu.edu.tr/upload/12607232/index.pdf.
Abstract (sommario):
The electrical currents generated in the heart propagate to the outward direction
of the body by means of conductive tissues and these currents yield a potential
distribution on the body surface. This potential distribution is recorded
and analyzed by a tool called electrocardiogram. It is not a problem, if this process
continues normallyhowever, when it is distorted by some abnormalities, the results will be fatal. Electrocardiography (ECG) is the technique dealing with the acquisition and interpretation of the electrical potentials recorded at the body surface due to the electrical activity of the heart. This can be realized by using one of the two approaches utilized in ECG namely
forward and inverse problems. The former one entails the calculation potentials on the body surface from known electrical activity of the heart and the latter one does the reverse. In this thesis, we will construct the body surface potentials in a realistic torso model starting from the epicardial potentials. In order to solve the forward problem, one needs a geometric model that includes the torso and the heart surfaces, as well as the intermediate surfaces or the intervening volume, and some assumptions about the electrical conductivity inside the enclosed volume. A realistic torso model has a complex geometry and this complexity makes it impossible to solve the forward problem analytically. In this study, Boundary Element Method (BEM) will be applied to solve the forward problem numerically. Furthermore, the effect of torso inhomogeneities such as lungs, muscles and skin to the body surface potentials will be analyzed numerically.
36
Pook, Torsten [Verfasser], Henner [Akademischer Betreuer] Simianer, Henner [Gutachter] Simianer, Timothy Mathes [Gutachter] Beissinger e Hans-Peter [Gutachter] Piepho. "Methods and software to enhance statistical analysis in large scale problems in breeding and quantitative genetics / Torsten Pook ; Gutachter: Henner Simianer, Timothy Mathes Beissinger, Hans-Peter Piepho ; Betreuer: Henner Simianer". Göttingen : Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2019. http://d-nb.info/1199608254/34.
37
Derenthal, Ulrich. "Geometry of universal torsors". Doctoral thesis, [S.l.] : [s.n.], 2006. http://webdoc.sub.gwdg.de/diss/2006/derenthal.
38
Zemzemi, Nejib. "Étude théorique et numérique de l'activité électrique du cœur: Applications aux électrocardiogrammes". Phd thesis, Université Paris Sud - Paris XI, 2009. http://tel.archives-ouvertes.fr/tel-00470375.
Abstract (sommario):
La modélisation du vivant, en particulier la modélisation de l'activité cardiaque, est devenue un défi scientifique majeur. Le but de cette thématique est de mieux comprendre les phénomènes physiologiques et donc d'apporter des solutions à des problèmes cliniques. Nous nous intéressons dans cette thèse à la modélisation et à l'étude numérique de l'activité électrique du cœur, en particulier l'étude des électrocardiogrammes (ECGs). L'onde électrique dans le cœur est gouvernée par un système d'équations de réaction-diffusion appelé modèle bidomaine ce système est couplé à une EDO représentant l'activité cellulaire. Afin simuler des ECGs, nous tenons en compte la propagation de l'onde électrique dans le thorax qui est décrite par une équation de diffusion. Nous commençons par une démonstrer l'existence d'une solution faible du système couplé cœur-thorax pour une classe de modèles ioniques phénoménologiques. Nous prouvons ensuite l'unicité de cette solution sous certaines conditions. Le plus grand apport de cette thèse est l'étude et la simulation numérique du couplage électrique cœur-thorax. Les résultats de simulations sont représentés à l'aide des ECGs. Dans une première partie, nous produisons des simulations pour un cas normal et pour des cas pathologiques (blocs de branche gauche et droit et des arhythmies). Nous étudions également l'impact de certaines hypothèses de modélisation sur les ECGs (couplage faible, utilisation du modèle monodomaine, isotropie, homogénéité cellulaire, comportement résistance-condensateur du péricarde,. . . ). Nous étudions à la fin de cette partie la sensibilité des ECGs par apport aux paramètres du modèle. En deuxième partie, nous effectuons l'analyse numérique de schémas du premier ordre en temps découplant les calculs du potentiel d'action et du potentiel extérieur. Puis, nous combinons ces schémas en temps avec un traîtement explicite du type Robin-Robin des conditions de couplage entre le cœur et le thorax. Nous proposons une analyse de stabilité de ces schémas et nous illustrons les résultats avec des simulations numériques d'ECGs. La dernière partie est consacrée à trois applications. Nous commençons par l'estimation de certains paramètres du modèle (conductivité du thorax et paramètres ioniques). Dans la deuxième application, qui est d'originie industrielle, nous utilisons des méthodes d'apprentissage statistique pour reconstruire des ECGs à partir de mesures ('électrogrammes). Enfin, nous présentons des simulations électro-mécaniques du coeur sur une géométrie réelle dans diverses situations physiologiques et pathologiques. Les indicateurs cliniques, électriques et mécaniques, calculés à partir de ces simulations sont très similaires à ceux observés en réalité.
39
Lin, Wen Tzao, e 林文藻. "Torsion Crack Problems of Thick Composite Laminates". Thesis, 1993. http://ndltd.ncl.edu.tw/handle/83863906187501025839.
40
Fili, Paul Arthur. "Orthogonal decompositions of the space of algebraic numbers modulo torsion". Thesis, 2010. http://hdl.handle.net/2152/ETD-UT-2010-05-1416.
Abstract (sommario):
We introduce decompositions determined by Galois field and degree of the space of algebraic numbers modulo torsion and the space of algebraic points on an elliptic curve over a number field. These decompositions are orthogonal with respect to the natural inner product associated to the L² Weil height recently introduced by Allcock and Vaaler in the case of algebraic numbers and the inner product naturally associated to the Néron-Tate canonical height on an elliptic curve. Using these decompositions, we then introduce vector space norms associated to the Mahler measure. For algebraic numbers, we formulate L[superscript p] Lehmer conjectures involving lower bounds on these norms and prove that these new conjectures are equivalent to their classical counterparts, specifically, the classical Lehmer conjecture in the p=1 case and the Schinzel-Zassenhaus conjecture in the p=[infinity] case.text
41
Chiu, I.-Cheng, e 邱益成. "The problems of the torsion and the conductivity for composite elliptical cylinder". Thesis, 2003. http://ndltd.ncl.edu.tw/handle/33886551507075441808.
Abstract (sommario):
碩士國立成功大學
土木工程學系碩博士班
91
This paper discused that after the composite confocal elliptical cylinder bearing torsion, the cross-section''s actions ,meat warping function of composite confocal elliptical cylinder. And, the two dimensions metrix which have the compsite confical elliptical inclusions with heat potential to find their potential and courrent''s actions. We can use continuity of boundary condition for two continuos confocial ellipical to construct the relation of the stuck of matrix to supply the methold to solve this kind of problems. Because of the conveninet. We ask the composit confocal elliptical with strong layers or weak layers for their warping functions. Except, we ask the confocal elliptiacl relations between inermost layer''s courrrent and the boundary of the potental''s order.
42
Amarnath, S. "Axisymmetric Contact Problems In Composite Elastic Media". Thesis, 1995. https://etd.iisc.ac.in/handle/2005/1630.
43
Amarnath, S. "Axisymmetric Contact Problems In Composite Elastic Media". Thesis, 1995. http://etd.iisc.ernet.in/handle/2005/1630.
44
He, I. L., e 何易霖. "Solving the elastic torsion problems with arbitrary bars by the meshless regularized integral equation method". Thesis, 2006. http://ndltd.ncl.edu.tw/handle/47543961361009582469.
Abstract (sommario):
碩士國立臺灣海洋大學
機械與機電工程學系
94
Abstract We treat the ill-posed system of linear equations by a regularization method to transform it to a linear stiff differential equations system. In order to overcome the difficulty of numerical instability, Liu【11】has combined the nonstandard finite difference method into the group-preserving scheme (NGPS) to obtain a stable numerical method for stiff equations. This paper applies the NGPS on the resulting differential equations obtained by adding a differential term on the left-hand side of linear equation, and proves that the new algorithms are unconditional stable. To increase the accuracy, the L-curve is used to select suitable regularization parameter. Several numerical examples are examined and compared with exact solutions revealing that the new algorithms have better computational efficiency and accuracy even for highly ill-conditioned linear equation with a large perturbation of the given data. Then, we consider using NGPS for solving following problems. The solutions of the torsion problem of uniform bars with arbitrary cross-section are presented by the first kind Fredholm integral equation along a selected circle. Then we consider the Lavrentiev regularization and Tikhonov regularization to treat the ill-posed problem. The termwise separable property of kernel function allows us to obtain a two-point boundary value solution. Numerical examples show the effectiveness of the new methods in providing excellent estimatesof the unknown data from the given boundary conditions. Keywords: Laplace equation, Arbitrary domain, Elastic torsion, Fredholm integral equation, Lavrentievregularization, Fourier series
45
Linß, Torsten [Verfasser]. "Layer adapted meshes for convection diffusion problems / Torsten Linß". 2007. http://d-nb.info/988207265/34.
46
Liao, Chia-Feng, e 廖家鋒. "Applications of New Error Estimation Technique in Torsion and Anti-plane shear Problems with Multiple Inclusions". Thesis, 2012. http://ndltd.ncl.edu.tw/handle/58186825440773168314.
Abstract (sommario):
碩士國立宜蘭大學
土木工程學系碩士班
100
In this thesis, we apply the developed new error estimation technique in boundary element (BEM) and the Trefftz method to estimate the numerical error which is formed in solving real engineering problems. Previous literatures authors, Chen (2010) and Jhong (2011) did not apply this technique in the real engineering problems. Therefore, this thesis will extend this technique to estimate the error caused by using BEM and Trefftz method for solving torsion problem and anti-plane shear problem with inclusions. The main characteristic of this technique is that the exact solution is unnecessary. By creating an auxiliary problem that the governing equation, domain shape and boundary condition type are the same as original problem, we can obtain the optimal number of elements in the BEM and the optimal number of collocation points in the Trefftz method. Finally, several real cases in literatures are taken to demonstrate the accuracy of the proposed estimation technique applied in real problem.
47
Dao-Long, Chen, e 陳道隆. "A study on mechanical problems of nanoscopic micro-structures under tension, compression and torsion by molecular dynamics theory". Thesis, 2001. http://ndltd.ncl.edu.tw/handle/30423327519791394547.
Abstract (sommario):
碩士國立成功大學
機械工程學系
89
The mechanical behaviors of nanoscopic structure of copper are studied by molecular dynamics simulation, and the results are compared with bulk material. In this study, the face center cubic structure of copper crystal is established as the experimental samples. The Gear’s fifth order predictor-corrector algorithms is adopted to calculate the positions, velocities and accelerations of atoms under displacement condition, while the interactions of atoms are dealt with Verlet’s neighbor lists and Morse’s potential. These computer simulations contain tree parts. The first part is to study what difference of stress and strain on the nanostructure and bulk structure of copper with vacancies under tensile. The second part is to study the mechanical behaviors of perfect nanostructure and bulk structure of copper under compression. And the third part is to study the mechanical behaviors of perfect nanostructure and bulk structure of copper again under torsion. These results will be compared with the behaviors in macroscopic world. After a series of computer simulations, we find: (1) the pre-stress in microscopic world shouldn’t be ignored, (2) the rate of strain should be larger than a specific value when simulating the behaviors of nanostructure and bulk structure, (3) for nanostructure with vacancies, the stresses are decreasing while the number of vacancies are increasing, and the bulk structure behaves in the same way except perfect crystal copper with crack, (4) the curves of stress-strain of bulk with periodic boundary conditions are more fluctuant than nanostructure, and different from the behavior in macroscopic world, (5) in compression test, the stress-strain curves will approach to a certain fixed curve while the strain rate is large for both nano- and bulk- structure; on the other hand, the curve of stress-strain becomes unstable while the strain rate is small, (6) in torsion test, the stresses of nanostructure will decrease while the torsion rate is increasing, but it is contrary for bulk structure. The results will help us to clarify the difference between macroscopic continuum and microscopic molecular dynamics in various tests, and gives us some new insights into the mechanical behaviors of nanostructure.
48
Sung, I.-Cheng, e 宋易澄. "Null-field integral equation approach for solving torsion problems of a circular bar with coated fibers or cracks". Thesis, 2016. http://ndltd.ncl.edu.tw/handle/03633984710584678311.
Abstract (sommario):
碩士國立臺灣海洋大學
河海工程學系
104
In this thesis, the null-field integral equation approach in conjunction with the degenerate kernel is used to solve the torsion problems of a circular bar with coated fibers or cracks. The degenerate kernel is employed to substitute the closed-form fundamental solution in the integral equations. In order to fully capture the geometry property, the boundary densities are expanding by Fourier series and eigenfunction expansion for circular boundary and elliptical boundary, respectively. For a circular bar with coated fibers, there are some difficulties on directly analyzing the bar since it has different materials in the bar. By using the technique of taking free body, the bar could be decomposed into three parts. One is a circular bar with circular holes, another is multiple individual circular-ring coatings, and the other is multiple circular fibers. After collocating points on each boundary and satisfying the continuity of displacement and equilibrium of force between interfaces, the unknown coefficients of Fourier series or eigenfunction can be determined by a linear algebraic system. For the problem of cracks in a bar, we adopt the limiting process of approaching the semi-minor axis of elliptical hole to be zero to simulate cracks. Finally, several numerical examples are employed to verify the feasibility and validity of the proposed approach. Besides, the partially and totally neutral behaviors for the composite bars are numerically analyzed.
49
Korneffel, Torsten [Verfasser]. "On combinatorial search problems which involve graphs / vorgelgt von Torsten Korneffel". 2007. http://d-nb.info/984062386/34.
50
Hein, Torsten [Verfasser]. "Analytische und numerische Studien zu inversen Problemen der Optionspreisbildung / vorgelegt von Torsten Hein". 2003. http://d-nb.info/969860986/34.