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Dubreuil, Sylvain. "Superposition modale probabiliste : application au dimensionnement des structures spatiales." Thesis, Toulouse, ISAE, 2014. http://www.theses.fr/2014ESAE0047/document.
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Ces travaux de thèse s’inscrivent dans le cadre de la prise en compte des incertitudes des paramètres d’entrée d’un modèle éléments finis de structures spatiales. L’approche probabiliste a été utilisée pour quantifier l’influence de l’aléa sur les fonctions de transfert.Nous avons proposé une adaptation de la méthode de superposition modale au cadre probabiliste, basée sur l’identification de la loi de probabilité des variables des fonctions de transfert. Le verrou technologique que constitue la construction de lois de probabilité de grande dimension a été levé par l’utilisation de la théorie des copules. Finalement, la méthodologie proposée a été validée sur un exemple industriel et les perspectives offertes par l’étude des structures de dépendances entre variables d’une fonction de transfert sont prometteuses<br>This PhD thesis aims at take into account input parameters uncertainty of space structures finite element models. To achieve this goal probabilistic approach is used to quantify the influence of randomness on transfer functions. An adaptation of modal superposition method to the probabilistic framework is proposed. This original approach is based on the identification of the probability distribution of transfer function variables. The main difficultyconcerns the construction of a large dimension probability distribution. This pointis tackled by the use of copula theory. Finally, the proposed methodology is validated onan industrial example. Moreover, the analysis of the dependence structures between the transfer function variables offers a lot of perspectives
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Gugel, Denis. "Ordnungsreduktion in der Mikrosystemtechnik." Doctoral thesis, Universitätsbibliothek Chemnitz, 2010. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-201001091.
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Die vorliegende Arbeit befasst sich mit der Methode der modalen Superposition als Ordnungsreduktionsverfahren in der Mikrosystemtechnik. Typische Anwendungsgebiete sind Inertialsensoren und dabei im Besonderen Drehratensensoren, für die die Simulation von zeitabhängigen Phänomenen von entscheidender Bedeutung ist.
Im Rahmen der Weiterentwicklung der Ordnungsreduktion nach der Methode der modalen Superposition ist es gelungen für typische lineare Kräfte eine auf analytischen Gleichungen basierende Beschreibung im reduzierten Raum zu finden. Für die Beschreibung von nichtlinearen Kräften ist im Rahmen dieser Arbeit ein Verfahren entwickelt worden, das es erlaubt, bestehende Modelle im Finite-Elemente-Raum in der modalen
Beschreibung zu nutzen.
In dieser Arbeit werden die theoretischen Grundlagen zur Berücksichtigung von Einflüssen der Aufbau- und Verbindungstechnik in ordnungsreduzierten Modellen dargestellt. Neben der Einkopplung äußerer Kräfte und der Veränderung der mechanischen Randbedingungen wird auch der Einfluss der Aufbau- und Verbindungstechnik auf die elektrostatischen Eigenschaften untersucht.
Die Parametrisierung des Verfahrens der modalen Superposition über Fit- und Interpolationsverfahren erlaubt es, parametrisierte ordnungsreduzierte Modelle für die zeitabhängige Systemsimulation zu generieren. Damit wird die Durchführung von Designoptimierung und die Berücksichtigung von Fertigungs- und Prozessschwankungen in ordnungsreduzierten Modellen auf Systemebene möglich.
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Gugel, Denis. "Ordnungsreduktion in der Mikrosystemtechnik." Doctoral thesis, Der Andere Verlag, Tönning, 2008. https://monarch.qucosa.de/id/qucosa%3A19359.
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Die vorliegende Arbeit befasst sich mit der Methode der modalen Superposition als Ordnungsreduktionsverfahren in der Mikrosystemtechnik. Typische Anwendungsgebiete sind Inertialsensoren und dabei im Besonderen Drehratensensoren, für die die Simulation von zeitabhängigen Phänomenen von entscheidender Bedeutung ist.
Im Rahmen der Weiterentwicklung der Ordnungsreduktion nach der Methode der modalen Superposition ist es gelungen für typische lineare Kräfte eine auf analytischen Gleichungen basierende Beschreibung im reduzierten Raum zu finden. Für die Beschreibung von nichtlinearen Kräften ist im Rahmen dieser Arbeit ein Verfahren entwickelt worden, das es erlaubt, bestehende Modelle im Finite-Elemente-Raum in der modalen
Beschreibung zu nutzen.
In dieser Arbeit werden die theoretischen Grundlagen zur Berücksichtigung von Einflüssen der Aufbau- und Verbindungstechnik in ordnungsreduzierten Modellen dargestellt. Neben der Einkopplung äußerer Kräfte und der Veränderung der mechanischen Randbedingungen wird auch der Einfluss der Aufbau- und Verbindungstechnik auf die elektrostatischen Eigenschaften untersucht.
Die Parametrisierung des Verfahrens der modalen Superposition über Fit- und Interpolationsverfahren erlaubt es, parametrisierte ordnungsreduzierte Modelle für die zeitabhängige Systemsimulation zu generieren. Damit wird die Durchführung von Designoptimierung und die Berücksichtigung von Fertigungs- und Prozessschwankungen in ordnungsreduzierten Modellen auf Systemebene möglich.
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Moussu, Florent. "Développement d'une méthode de détermination des constantes élastiques d'un matériau orthotrope." Vandoeuvre-les-Nancy, INPL, 1995. http://www.theses.fr/1995INPL033N.
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Le développement de nouveaux matériaux pose le problème de la connaissance de leurs constantes élastiques. Les méthodes de mesure des constantes élastiques sont nombreuses, mais ne permettent que très rarement de déterminer simultanément et de façon non destructive un grand nombre des composantes du tenseur des rigidités élastiques. Grâce l'essor des outils de calcul numérique et de traitement du signal, une nouvelle méthode est développée, basée sur l'analyse du comportement dynamique d'une plaque rectangulaire complètement libre à orthotropie spéciale. Deux modèles théoriques sont décrits selon que la plaque est mince ou épaisse conduisant aux équations aux dérivées partielles du mouvement et à l'expression des conditions aux limites. La résolution en terme de fréquences propres et modes propres de ces équations n'est pas simple, et par souci d'économie de temps calcul, une méthode semi-analytique originale est développée: il s'agit de la méthode dite de superposition qui permet de décomposer un problème qui n'admet pas de solution analytique, en deux sous problèmes dont la solution peut être décrite grâce à des développements en séries trigonométriques. Par ailleurs, un dispositif expérimental est mis au point, permettant, grâce à une bonne simulation des conditions aux limites complètement libres et à l'utilisation d'une métrologie sans contact, de déterminer avec précision les fréquences propres et modes propres d'une plaque. Sachant calculer théoriquement et mesurer expérimentalement les fréquences propres de la plaque, un algorithme est développé afin de déterminer les quatre ou six constantes élastiques (selon qu'elle est mince ou épaisse) régissant au mieux au sens des moindres carrés son comportement dynamique. Finalement, des résultats expérimentaux valident la méthodologie proposée et montrent sa précision et sa sensibilité
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Bennini, Fouad. "Ordnungsreduktion von elektrostatisch-mechanischen Finite Elemente Modellen für die Mikrosystemtechnik." Doctoral thesis, Universitätsbibliothek Chemnitz, 2005. http://nbn-resolving.de/urn:nbn:de:swb:ch1-200501368.
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In der vorliegenden Arbeit wird eine Prozedur zur Ordnungsreduktion von Finite Elemente
Modellen mikromechanischer Struktur mit elektrostatischem Wirkprinzip entwickelt und
analysiert. Hintergrund der Ordnungsreduktion ist eine Koordinatentransformation von
lokalen Finite Elemente Koordinaten in globale Koordinaten. Die globalen Koordinaten des
reduzierten Modells werden durch einige wenige Formfunktionen beschrieben. Damit wird
das Makromodell nicht mehr durch lokale Knotenverschiebungen beschrieben, sondern durch
globale Formfunktionen, welche die gesamte Deformation der Struktur beeinflussen. Es wird
gezeigt, dass Eigenvektoren der linearisierten mechanischen Struktur einfache und effiziente
Formfunktionen darstellen. Weiterhin kann diese Methode für bestimmte Nichtlinearitäten
und für verschiedene in Mikrosystemen auftretende Lasten angewendet werden. Das Ergebnis
sind Makromodelle, die über Klemmen in Systemsimulatoren eingebunden werden können,
die Genauigkeiten einer Finite Elemente Analyse erreichen und für Systemsimulationen
typische Laufzeitverhalten besitzen.
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Jakel, Roland. "Linear Dynamic System Analyses with Creo Simulate – Theory & Application Examples, Capabilities, Limitations –." Universitätsbibliothek Chemnitz, 2017. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-qucosa-225992.
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1. Einführung in die Theorie dynamischer Analysen mit Creo Simulate 2. Modalanalysen (Standard und mit Vorspannung) 3. Dynamische Analysen einschließlich Klassifizierung der Analysen; einige einfache Beispiele für eigene Studien (eine Welle unter Unwuchtanregung und ein Ein-Massen-Schwinger) sowie etliche Beispiele größerer dynamischer Systemmodelle aus unterschiedlichsten Anwendungsbereichen 4. Feedback an den Softwareentwickler PTC (Verbesserungsvorschläge und Softwarefehler) 5. Referenzen<br>1. Introduction to dynamic analysis theory in Creo Simulate 2. Modal analysis (standard and with prestress) 3. Dynamic analysis, including analysis classification, some simple examples for own self-studies (shaft under unbalance excitation and a one-mass-oscillator) and several real-world examples of bigger dynamic systems 4. Feedback to the software developer PTC (enhancement requests and code issues) 5. References
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Jakel, Roland. "Berechnung von Schockspektren und praktische Anwendung der dynamischen Stoßanalyse in Creo Elements / Pro Mechanica." Universitätsbibliothek Chemnitz, 2011. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-qucosa-68407.
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Der Vortrag stellt Idee und Grundlagen der Berechnung von Schockantwortspektren dar. Er zeigt, wie man exemplarisch für einen Halbsinusstoß das Schockantwortspektrum in der PTC FEM-Software Creo Elements / Pro Mechanica berechnen kann. Die Schockantworten eines Ein- und Zweimassenschwingers werden sowohl zeitaufgelöst als auch über die dynamische Stoßanalyse berechnet. Die modalen Superpositionsmethoden "Absolute Summe" und "SRSS" (Square Root of the Sum of the Squares - geometrischer Mittelwert) werden vorgestellt. Als reales Beispiel werden Schockanalysen für verschiedene Halbsinusimpulse mit einem Wärmebildgerät der Firma Carl Zeiss Optronics GmbH durchgeführt und mit einer zeitaufgelösten Analyse verglichen. Abschließend wird auf die Erzeugung von Antwortspektren für die Substrukturauslegung eingegangen<br>The presentation explains idea and fundamentals of shock response spectra analysis. With help of the PTC FEM-software Creo Elements / Pro Mechanica the shock response spectra (SRS) for an exemplary half sine shock is calculated. The shock response of a one-mass and a two-mass oscillator are analyzed per dynamic time as well as per dynamic shock analysis. The modal superposition methods "absolute sum" and "SRSS" (Square Root of the Sum of the Squares) are explained. The method is applied for different half sine shocks on a realistic example: A thermal imaging system of the company Carl Zeiss Optronics GmbH. Finally, the creation of response spectra for global-local analysis is explained
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Johansson, Jonas. "Investigation of Mode Superposition as Modelling Approach for Crankshaft Torsion." Thesis, Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-69453.
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With tougher emission standards for heavy duty trucks, good control of the engine is of importance. By taking into consideration the torsional vibrations occurring in the crankshaft, the engine control can be improved. This could be done by implementing a torsion model that would give feedback to the engine control unit to reduce the cycle-to-cycle variations in the cylinders, which is partly due to the torsion in the crankshaft. It is therefore of interest to determine if a torsion model can be developed with a reduced computational complexity and still have sufficient accuracy. In this thesis a model was developed in Matlab for estimation of torsion in the crankshaft of an inline 6 cylinder diesel engine. By applying Newtons second law, the equations of motion that describe the torsional vibrations in the crankshaft were set up. The equations of motion were transformed using modal analysis and with the use of mode superposition it was investigated how reducing the number of vibrational modes in the model, affected the models accuracy in its estimation of torsion. Two model reductions were evaluated where the first three and four vibrational modes were used to calculate the torsional displacement between the flywheel and the cylinders. Using measured pressure curves for a number of operating points of the engineas input to the model, results were produced for different crank angle intervalsshowing deviations between the developed torsion models and a reference models estimation of torsion. Due to the damping approximation used in the model, high initial deviations could be found at certain operating points beforereducing the number of vibrational modes. These initial deviations weregreatest for the first two cylinders. Results from the model reductions showed that using the first three vibrational modes in the torsion model, is sufficient for estimating the torsional displacement between the flywheel and all cylinderswith an accuracy of within 0.1 degrees, with the exception of the first two cylinders for the early and late combustion interval.
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Robbins, Donald H. "Hierarchical modeling of laminated composite plates using variable kinematic finite elements and mesh superposition." Diss., Virginia Tech, 1993. http://hdl.handle.net/10919/40117.
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Bond, Brian H. "Development of tension and compression creep models for wood using the time-temperature superposition principle." Thesis, This resource online, 1993. http://scholar.lib.vt.edu/theses/available/etd-10312009-020305/.
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AGUIAR, PAULO ROBERTO ROCHA. "DYNAMIC RESPONSE OF LINEAR STRUCTURES DISCRETIZED BY THE FINITE ELEMENT METHOD USING MODAL SUPERPOSITION: THE LANCZOS METHOD." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 1997. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=24832@1.
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Neste trabalho desenvolve-se a técnica da superposição modal para a solução temporal das equações do equilíbrio dinâmico, resultantes da discretização espacial de estruturas pelo método de elementos finitos. Para esta solução numérica são empregados os auto-pares solução do problema de autovalor generalizado, obtido das características de vibração sem amortecimento das estruturas discretizadas. É proposto um algorítmo em que a auto-solução é obtida combinando-se os métodos de Lanczos e QR. Esta solução é utilizada através de uma transformação da base de solução, desacoplando as equações de equilíbrio dinâmico através da técnica da superposição modal. A análise é desenvolvida considerando-se sistemas sem característica de amortecimento porém, também são apresentadas soluções analíticas para sistemas amortecidos. O algoritmo foi implementado em computador e alguns resultados numéricos são comparados com outras soluções analíticas e/ou numéricas verificando-se o desempenho computacional e a aplicabilidade do método proposto na solução de sistemas dinâmicos.<br>This work deals with the modal superposition technique developed to obtain the solution of the dinamic equilibrium equations resulting from the finite element space discretization method. For that numerical solution the eigenpair solution associated to the eigenvector problem arisen from the vibration characteristics of undamped discretized structures. It is proposed an algorithm where the eigensolution is obtained combining the Lanczos and the QR methods. This solution, through base of definition transformation, is used to decouple the dinamic equilibrium equations with the modal superposition method. The analises presented in this work were developed considering systems without damping. However, analytical solution for systems with damping are also presented. The algorithm was implemented in the computer and some numerical results are compared to the other analytical and/or numerical solution to identify its performance and applicability in the solution of dynamic systems.
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Jakel, Roland. "Lineare und nichtlineare Analyse hochdynamischer Einschlagvorgänge mit Creo Simulate und Abaqus/Explicit." Universitätsbibliothek Chemnitz, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-qucosa-171812.
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Der Vortrag beschreibt wie sich mittels der unterschiedlichen Berechnungsverfahren zur Lösung dynamischer Strukturpobleme der Einschlag eines idealisierten Bruchstücks in eine Schutzwand berechnen lässt. Dies wird mittels zweier kommerzieller FEM-Programme beschrieben: a.) Creo Simulate nutzt zur Lösung die Methode der modalen Superposition, d.h., es können nur lineare dynamische Systeme mit rein modaler Dämpfung berechnet werden. Kontakt zwischen zwei Bauteilen lässt sich damit nicht erfassen. Die unbekannte Kraft-Zeit-Funktion des Einschlagvorganges muss also geeignet abgeschätzt und als äußere Last auf die Schutzwand aufgebracht werden. Je dynamischer der Einschlagvorgang, desto eher wird der Gültigkeitsbereich des zugrunde liegenden linearen Modells verlassen. b.) Abaqus/Explicit nutzt ein direktes Zeitintegrationsverfahren zur schrittweisen Lösung der zugrunde liegenden Differentialgleichung, die keine tangentiale Steifigkeitsmatrix benötigt. Damit können sowohl Materialnichtlinearitäten als auch Kontakt geeignet erfasst und damit die Kraft-Zeit-Funktion des Einschlages ermittelt werden. Auch bei extrem hochdynamischen Vorgängen liefert diese Methode ein gutes Ergebnis. Es müssen dafür jedoch weit mehr Werkstoffdaten bekannt sein, um das nichtlineare elasto-plastische Materialverhalten mit Schädigungseffekten korrekt zu beschreiben. Die Schwierigkeiten der Werkstoffdatenbestimmung werden in den Grundlagen erläutert<br>The presentation describes how to analyze the impact of an idealized fragment into a stell protective panel with different dynamic analysis methods. Two different commercial Finite Element codes are used for this: a.) Creo Simulate: This code uses the method of modal superposition for analyzing the dynamic response of linear dynamic systems. Therefore, only modal damping and no contact can be used. The unknown force-vs.-time curve of the impact event cannot be computed, but must be assumed and applied as external force to the steel protective panel. As more dynamic the impact, as sooner the range of validity of the underlying linear model is left. b.) Abaqus/Explicit: This code uses a direct integration method for an incremental (step by step) solution of the underlying differential equation, which does not need a tangential stiffness matrix. In this way, matieral nonlinearities as well as contact can be obtained as one result of the FEM analysis. Even for extremely high-dynamic impacts, good results can be obtained. But, the nonlinear elasto-plastic material behavior with damage initiation and damage evolution must be characterized with a lot of effort. The principal difficulties of the material characterization are described
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Holm, Bleicke. "SFC, un modèle de superposition de contours multiparamétriques pour la génération automatique de la prosodie : apprentissage automatique et application à l'énonciation de formules mathématiques." Grenoble INPG, 2003. http://www.theses.fr/2003INPG0045.
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Cette thèse traite de la génération automatique de la prosodie en vue de la synthèse de la parole à partir de texte. Nous partons de l'hypothèse que la prosodie encode dans le signal acoustique les instances de fonctions (para-)linguistiques (hiérarchisation, segmentation, attitudes etc. ) par des contours multiparamétriques dont l'étendue égale la portée des fonctions. Ces contours interagissent par superposition additive. Nous proposons un modèle, le SFC "Superposition of Functional Contours", qui réalise la factorisation de réalisations prosodiques en contours à l'aide d'une analyse par la synthèse. La décomposition obtenue est optimale par rapport à un ensemble de données (corpus) au sens où la forme des contours relève uniquement des besoins statistiques sous les contraintes fonctionnelles que nous imposons. Le SFC a été appliqué à des corpora d'oralisation de formules mathématiques et de phrases isolées en français. Il a été également appliqué à l'allemand et au galicien.
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Gatti, Anderson Carlos. "Analise dinamica linear de porticos planos pelo metodo dos elementos finitos." [s.n.], 2006. http://repositorio.unicamp.br/jspui/handle/REPOSIP/257864.
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Orientador: Aloisio Ernesto Assan<br>Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Civil, Arquitetura e Urbanismo<br>Made available in DSpace on 2018-08-07T10:17:54Z (GMT). No. of bitstreams: 1
Gatti_AndersonCarlos_M.pdf: 1799347 bytes, checksum: c5db751be8130693e5a2966d279bc22e (MD5)
Previous issue date: 2006<br>Resumo: Neste trabalho estuda-se o comportamento de pórticos planos submetidos a ações dinâmicas. Apresenta-se, inicialmente, a Equação de Movimento de Lagrange através das variações das energias cinética, potencial mais o trabalho das forças não conservativas. Em seguida, pelo emprego do Método dos Elementos Finitos são desenvolvidas as matrizes de rigidez, massa e amortecimento para o elemento de pórtico plano. O amortecimento introduzido é o de Rayleigh. Estudam-se dois métodos para a realização da análise dinâmica: o método de Newmark e o Método da Superposição Modal, também sendo realizado um estudo do problema de autovalor e autovetor pelo emprego do Método das Potências e o Método da Deflação de Wielandt. Os autovalores e autovetores fornecerão as freqüências naturais e os modos de vibração da estrutura. Finalmente, são mostrados exemplos numéricos para a análise do comportamento dos pórticos planos<br>Abstract: In this work, it is studied the behavior of plane frames submitted to dynamic loads. First of all Lagrange¿s Equations of Motion is presented by the kinetic and potential energy variation plus the work of the nonconservative forces. Next, the stiffness, mass and damping matrices for the plane frame element are developed with the use of the Finite Element Method. Damping is introduced from the Rayleigh damping. Both Newmark Method and Modal Superposition Method are studied to carry out the dynamic analysis. It is also carried out a study of the eigenvalue problem by Power Method and Wielandt Deflation Method. Eigenvalues and eigenvectors will provide the natural frequencies and normal modes of the structure, respectively. Finally, numerical examples are related to the analysis of the plane frameworks behavior<br>Mestrado<br>Estruturas<br>Mestre em Engenharia Civil
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Chitikireddy, Ravi. "Laser generated thermoelastic waves in finite and infinite transversely isotropic cylinders." Taylor & Francis Group, LLC, 2010. http://hdl.handle.net/1993/8445.
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This thesis presents a theoretical study of thermoelastic guided waves in cylinders in the context of Lord-Shulman generalized theory of thermoelasticity. Two different methods were formulated to study dispersion relations in infinite cylinders. One of them is a Semi Analytical Finite Element (SAFE) method and the other is an analytical method. In the SAFE method, the dispersion equation has been formulated as a generalized eigenvalue problem by treating radial displacement and temperature with a one dimensional finite element model through the thickness of the cylinder. In the analytical method, displacement potentials are introduced to obtain the dispersion relations of guided wave modes. This method is applicable to isotropic cylinders and has been developed primarily to cross check the SAFE formulation. Frequency spectra obtained by both methods for an isotropic cylinder have shown excellent agreement with each other. Since the SAFE method can be used for an anisotropic composite cylinder, guided wave modes for anisotropic and composite cylinders are presented.
Transient analysis of ultrasonic guided waves generated by concentrated heating of the outer surface of an infinite anisotropic cylinder has also been studied. The SAFE method is employed to model the response of a cylinder due to a pulsed laser focused on its surface. Green’s functions were constructed numerically by superposition of guided wave modes in frequency and wave number domains. Time histories of the propagating modes are then calculated by applying an inverse Fourier transformation in the time domain. Transient radial displacements of longitudinal and flexural modes of a silicon nitride cylinder are presented.
Propagation of thermoelastic waves in finite length circular cylinders have also been investigated. The SAFE method is used to simulate the guided wave modes in the cylinder. Frequency spectra obtained by the SAFE formulation, for a finite length transversely isotropic cylinder, are validated by comparing the numerical results with relevant publications. Frequency spectra for axisymmetric and asymmetric modes in a silicon nitride finite cylinder with both ends insulated and restrained by frictionless rigid walls are presented. The plain strain problem of circumferential guided waves is also studied and the results are validated for an isothermal case.
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Jurina, Marek. "Aerodynamická analýza poddajného křídla kluzáku." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2018. http://www.nusl.cz/ntk/nusl-377517.
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This thesis deals with determination of effect of wing flexibility on load distribution. FSI analysis using modal superposition was used for determination of effect of wing flexibility. Analysis was verified by analytic calculation. Differences of load distribution, between rigid and flexible wing, was determined for the selected flight regimes. Change of the bending moment was up to 3,9 %. Thesis shows importance of including effect of wing flexibility for sailplane design.
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Gonzalez, Ines M. "THEORETICAL STUDY OF THE STRUCTURES AND ENERGETICS OF AROMATIC CLUSTERS: DEVELOPMENT OF RELIABLE AND PRACTICAL THEORETICAL MODELS FOR INTERMOLECULAR POTENTIALS." University of Akron / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=akron1164652307.
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Blanpain-Avet, Pascal. "Étude des paramètres gouvernant l’effet du backpulse et de la superposition de pulsations de débit et de pression lors de la microfiltration du jus de pomme sur membranes minérales." Compiègne, 1991. http://www.theses.fr/1991COMPD360.
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Ce travail concerne l'étude de l'effet des paramètres gouvernant deux techniques hydrodynamiques, le backpulse (ou contre-lavage) et le débit pulsé, qui permettent de lutter contre le colmatage des membranes. Ces deux techniques ont été appliquées à la microfiltration tangentielle du jus de pomme sur membranes minérales. Nous avons, dans une première partie, cherché les principaux paramètres responsables de l'efficacité du backpulse. Un modèle, basé sur un flux de soluté en rétro-transport induit hydrodynamiquement, est proposé afin de décrire la reformation d'une couche de dépôt entre deux rétrofiltrations. Dans une deuxième partie, nous avons cherché à optimiser l'efficacité de la technique de débit pulsé en batch monotube en terme de flux de filtration. Un signal de débit et de pression présentant une faible consommation énergétique additionnelle nous a permis d'atteindre une augmentation de flux de 55%. La dernière partie a concerné la mise en œuvre du débit pulsé appliqué cette fois à l'échelle pilote sur un banc muni d'une boucle de recirculation.
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Kolchuzhin, Vladimir. "Methods and Tools for Parametric Modeling and Simulation of Microsystems based on Finite Element Methods and Order Reduction Technologies." Doctoral thesis, Universitätsbibliothek Chemnitz, 2010. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-201000550.
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In der vorliegenden Arbeit wird die Entwicklung eines effizienten Verfahrens zur parametrischen Finite Elemente Simulation von Mikrosystemen und zum Export dieser Modelle in Elektronik- und Systemsimulationswerkzeuge vorgestellt. Parametrische FE-Modelle beschreiben den Einfluss von geometrischen Abmessungen, Schwankungen von Materialeigenschaften und veränderten Umgebungsbedingungen auf das Funktionsverhalten von Sensoren und Aktuatoren. Parametrische FE-Modelle werden für die Auswahl geeigneter Formelemente und deren Dimensionierung während des Entwurfsprozesses in der Mikrosystemtechnik benötigt. Weiterhin ermöglichen parametrische Modelle Sensitivitätsanalysen zur Bewertung des Einflusses von Toleranzen und Prozessschwankungen auf die Qualität von Fertigungsprozessen. In Gegensatz zu üblichen Sample- und Fitverfahren wird in dieser Arbeit eine Methode entwickelt, welche die Taylorkoeffizienten höherer Ordnung zur Beschreibung des Einflusses von Designparametern direkt aus der Finite-Elemente- Formulierung, durch Ableitungen der Systemmatrizen, ermittelt. Durch Ordnungsreduktionsverfahren werden die parametrischen FE-Modelle in verschiedene Beschreibungssprachen für einen nachfolgenden Elektronik- und Schaltungsentwurf überführt. Dadurch wird es möglich, neben dem Sensor- und Aktuatorentwurf auch das Zusammenwirken von Mikrosystemen mit elektronischen Schaltungen in einer einheitlichen Simulationsumgebung zu analysieren und zu optimieren<br>The thesis deals with advanced parametric modeling technologies based on differentiation of the finite element equations which account for parameter variations in a single FE run. The key idea of the new approach is to compute not only the governing system matrices of the FE problem but also high order partial derivatives with regard to design parameters by means of automatic differentiation. As result, Taylor vectors of the system’s response can be expanded in the vicinity of the initial position capturing dimensions and physical parameter. A novel approaches for the parametric MEMS simulation have been investigated for mechanical, electrostatic and fluidic domains in order to improve the computational efficiency. Objective of reduced order modeling is to construct a simplified model which approximates the original system with reasonable accuracy for system level design of MEMS. The modal superposition technique is most suitable for system with flexible mechanical components because the deformation state of any flexible system can be accurately described by a linear combination of its lowest eigenvectors. The developed simulation approach using parametric FE analyses to extract basis functions have been applied for parametric reduced order modeling. The successful implementation of a derivatives based technique for parameterization of macromodel by the example of microbeam and for exporting this macromodel into MATLAB/Similink to simulate dynamical behavior has been reported
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Hakl, Petr. "Vytvoření hydrologického modelu pro odvození maximálních odtoků z malých povodí." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2020. http://www.nusl.cz/ntk/nusl-409727.
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The aim of the thesis is to set a hydrology model based on existed methodology DesQ-MaxQ, which comes from "Designing flows from a very small catchments" established in 1989. The model is able to set a nearest meteorology station and his 24-hours rainfall depths for periods of repetition 2,5,10,20,50 and 100 years. Substitute rainfall depths are set by "reduction of 24-hours rainfall depths" methodology. According to hydraulic and hydrology conditions of catchment, duration of the critical rains for each period of repetition are set also peak flow rates and total runoffs from the catchment. Application can work in two modes - "one slope" and "two slopes". The second option also includes calculation of design duration for the model catchment and superposition of hydrograph. Application RainRunoff was develop in C# programming language with graphic user interface and option to exports hydrographs.
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Maruyama, Fábio Massatoshi. "Análise estrutural dinâmica de um vaso de pressão (reator PWR) utilizando o método DDAM." Universidade de São Paulo, 2012. http://www.teses.usp.br/teses/disponiveis/3/3135/tde-26072013-144247/.
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O objetivo deste trabalho é verificar a aplicação do Dynamic Design Analysis Method DDAM na análise de estruturas submetidas a carregamentos de choque. Esse método foi desenvolvido pela Marinha Norte Americana e se propõe a estimar esforços inercias provenientes das respostas de equipamentos de bordo, sejam de navios ou submarinos, a cargas impulsivas, mais precisamente, ondas de choque submarinas. Para a compreensão plena dessa metodologia, foi necessário um estudo sobre vibrações e espectros de resposta, tópicos teóricos que fundamentam esse procedimento. Devido à escassez de informações divulgadas por se tratar de conteúdo militar, foi realizado um estudo de caso para uma estrutura simples, uma viga engastada e seus resultados foram comparados com um prévio trabalho publicado. Com isso, foi possível a aplicação do DDAM em uma estrutura mais complexa como o vaso do reator nuclear do tipo PWR de um submarino, ainda que em um modelo simplificado desse equipamento. No entanto, os resultados mostraram a validade do uso do DDAM na análise estrutural dinâmica de equipamentos de uma maneira qualitativa.<br>The main purpose of this dissertation is to verify the use of the Dynamic Design Analysis Method DDAM in the study of structures subjected to shock loadings. This method was developed by the U.S. Navy and is intended to estimate inertial forces resultant from the response of shipboard equipment, from surface ships or submarines, due to impulsive loads or, more precisely, underwater pressure shock waves. To fully comprehend this method, it was necessary to acknowledge fundamentals of dynamics of structures like free vibrations, response spectrum analysis correlated topics. And due to lack of public information since it is a military technology, a case study of a cantilever beam was done with its results compared to a previous published paper. Then, the DDAM was applied to a more complex structure a PWR nuclear reactor vase simplified model, in order to show the effectiveness of the method in dynamic structural analysis.
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Garafolo, Nicholas Gordon. "AN EXPERIMENTAL INVESTIGATION OF MULTIPLE MODE EXCITATION OF AN INTEGRALLY BLADED DISK." University of Akron / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=akron1164047919.
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Deverge, Mickael. "Propriétés mécaniques et rhéologiques des mousses de polymères réticulés." Phd thesis, Université du Maine, 2006. http://tel.archives-ouvertes.fr/tel-00133963.
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L'utilisation des matériaux cellulaires à base de polymères type mousse gagne de plus en plus de terrain, notamment pour l'absorption acoustique. L'objectif de ce travail est de présenter de nouvelles approches pour la caractérisation de ces matériaux.<br /> Diverses méthodes ont été développées afin de caractériser ces matériaux, en particulier leur domaine linéaire, zone privilégiée pour l'absorption acoustique et la détermination des paramètres mécaniques courants. Cependant ces caractérisations restent souvent limitées à une faible plage fréquentielle. Une première étude présente ici le comportement linéaire sur une large gamme de fréquences grâce à l'application du principe de Superposition Temps-Température (TTS). L'utilisation du TTS sur une famille de mousses obtenues avec le même polymère, de même densité, mais dont la taille des pores est différente, met en évidence deux aspects importants: seulement 3 % du squelette solide participe à la transmission de la contrainte, et le module élastique à fréquence nulle décroît avec la taille des pores.<br /> Les mousses de polymères sont certes souvent utilisées dans leur domaine linéaire, mais leur comportement mécanique diffère à de plus forts niveaux de déformation. Les courbes en contrainte-déformation présentent un comportement en hystérésis, avec trois zones de comportement distinctes (linéaire, flambement et densification). Il existe d'autres phénomènes en hystérésis qui ont été plus simplement modélisés, par exemple à l'aide de la théorie de Preisach-Krasnoselskii-Mayergoyz (PKM) issue du magnétisme. Une seconde partie de ce travail présente une nouvelle extension de cette théorie PKM aux mousses de polymères réticulés à cellules ouvertes, soumises à de grandes déformations: nous pouvons ainsi modéliser l'hystérésis observée expérimentalement, à partir d'une distribution d'hysterons microscopiques contenus dans un espace de Preisach-Mayergoyz.<br /> Dans une troisième partie, l'influence de l'histoire passée des contraintes sur la mesure des paramètres mécaniques d'une mousse est étudiée, et plus particulièrement la rhéologie de ces mousses dans le cadre de la relaxation de compression, en distinguant deux mécanismes, l'un en zone linéaire de chargement et l'autre en dehors. Liée à l'histoire des contraintes passées, ce second mécanisme de relaxation permet la réduction des contraintes par réarrangement topologique des poutres de la mousse.
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Kreis, Eri Sato. "ANA-PSp: um sistema computacional para análise aeroelástica de pontes suspensas por modelos matemáticos reduzidos." Universidade de São Paulo, 2007. http://www.teses.usp.br/teses/disponiveis/3/3144/tde-31032008-151227/.
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As características arquitetônicas e o desempenho estrutural de pontes suspensas, estaiadas ou pênseis, têm determinado a sua crescente utilização em obras de arte destinadas a vencer grandes vãos. Essa utilização crescente que ocorreu no mundo nas últimas décadas se repete agora nos últimos anos no país. Várias dessas obras estão em execução e em projeto. Um dos aspectos relevantes na análise estrutural das pontes suspensas é o de seu comportamento quando submetidas à ação do vento. Apresenta-se o sistema computacional ANA-PSp desenvolvido especialmente para o estudo do movimento de tabuleiros de pontes suspensas sujeitas a esforços aeroelásticos e aerodinâmicos. Esse sistema computacional formado por um conjunto de subsistemas, é elaborado para a análise aeroelástica de pontes suspensas sob a ação de vento e permite análises paramétricas extensas dos fenômenos de drapejamento (flutter) e de martelamento (buffeting). A discretização da estrutura é efetuada pelo método dos elementos finitos e a redução dos graus de liberdade é realizada por superposição modal com modos selecionados que melhor descrevem os movimentos do tabuleiro. Utiliza-se modelo matemático reduzido para a análise multimodal no domínio do tempo e da freqüência. A velocidade crítica ou velocidade de drapejamento é determinada por procedimento de autovalores complexos com a obtenção de freqüências e taxas de amortecimentos modais para várias velocidades do vento. Adicionalmente, o fenômeno do drapejamento é estudado por séries temporais de respostas de coordenadas generalizadas e de deslocamentos selecionados e por análise espectral dessas séries temporais, que permitem a verificação das características de vibração do tabuleiro da ponte no domínio da freqüência. O estudo do fenômeno de martelamento considera esforços aeroelásticos determinísticos e esforços aerodinâmicos estocásticos e apresentam-se resultados em espectros de potência de deslocamentos e em desvios padrão de deslocamentos ao longo do tabuleiro. Para validar o sistema ANA-PSp, apresentam-se estudos de caso para a ponte estaiada da Normandia, para a ponte pênsil colapsada de Tacoma Narrows e para a ponte estaiada projetada, mas não executada, sobre o Rio Tietê e localizada na extremidade do complexo viário Jacu-Pêssego.<br>The architectonic characteristics and the structural performance of suspension bridges and cable-stayed bridges have determined their growing use on large span bridges. This growing usage, which has occurred world-wide during the last decades, is now being repeated in Brazil during the last few years. Several such bridges are presently either undergoing construction or being designed. One of the outstanding aspects in the structural analysis of suspension bridges is their behavior under wind action. This paper presents the computer system ANA-PSp, specially developed for studying the movement of suspended bridge decks under aeroelastic and aerodynamic forces. This computer system is formed by a group of subsystems and is created for aeroelastic analysis of suspended bridges under wind action. It allows extended parametric analyses of the flutter and the buffeting phenomena. Structural discretization is done by the finite element method and the reduction of degrees of freedom is obtained by modal superposition of the selected modes which best describe the deck movements. A reduced mathematical model is used for the multimodal analysis in the time and frequency domains. Critical velocity or flutter velocity is determined by a procedure of complex eigenvalues which obtains frequencies and damping ratios for different wind speeds. Additionally, the flutter phenomenon is studied by temporal series of answers to generalized coordinate responses and of selected displacements by spectral analysis of such temporal series, which allow us to verify the characteristics of the vibrations of the bridge deck in the frequency domain. The study of the buffeting phenomenon considers deterministic aeroelastic and stochastic aerodynamic forces. The paper presents results in displacement power spectra and in the standard deviation of displacements along the deck. In order to validate system ANA-PSp, case studies are presented for the cable-stayed Ponte de Normandie in Le Havre (France), for the collapsed suspension bridge on Tacoma Narrows and for the cable-stayed bridge, already designed but not built, on Tietê River, located at one end of the highway complex Jacu-Pêssego (São Paulo, SP, Brazil).
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Bennini, Fouad. "Ordnungsreduktion von elektrostatisch-mechanischen Finite Elemente Modellen für die Mikrosystemtechnik: Ordnungsreduktion von elektrostatisch-mechanischen FiniteElemente Modellen für die Mikrosystemtechnik." Doctoral thesis, 2004. https://monarch.qucosa.de/id/qucosa%3A18384.
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In der vorliegenden Arbeit wird eine Prozedur zur Ordnungsreduktion von Finite Elemente
Modellen mikromechanischer Struktur mit elektrostatischem Wirkprinzip entwickelt und
analysiert. Hintergrund der Ordnungsreduktion ist eine Koordinatentransformation von
lokalen Finite Elemente Koordinaten in globale Koordinaten. Die globalen Koordinaten des
reduzierten Modells werden durch einige wenige Formfunktionen beschrieben. Damit wird
das Makromodell nicht mehr durch lokale Knotenverschiebungen beschrieben, sondern durch
globale Formfunktionen, welche die gesamte Deformation der Struktur beeinflussen. Es wird
gezeigt, dass Eigenvektoren der linearisierten mechanischen Struktur einfache und effiziente
Formfunktionen darstellen. Weiterhin kann diese Methode für bestimmte Nichtlinearitäten
und für verschiedene in Mikrosystemen auftretende Lasten angewendet werden. Das Ergebnis
sind Makromodelle, die über Klemmen in Systemsimulatoren eingebunden werden können,
die Genauigkeiten einer Finite Elemente Analyse erreichen und für Systemsimulationen
typische Laufzeitverhalten besitzen.
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Chuang, Chun-Kai, and 莊淳凱. "Symplectic modal superposition method for H∞ control of earthquake-excited structures." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/39077750098503269766.
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Ma, Ruei-Fu, and 馬瑞符. "Dynamic Analysis of Cable-Stayed Bridge by Modal Superposition Method－Square Root of Sum of Squares Method（SRSS）and Complete Quadratic Combination Method（CQC）." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/95066657228312479667.
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碩士<br>中原大學<br>土木工程研究所<br>94<br>In the paper, SAP2000, a finite element software, is used to analyze the natural frequency and vibration shapes in order to investigate if the cable-stayed bridges will appear coupling from resonance under earthquake effects. Moreover, we study dynamic behaviors of cable-stayed bridges by using modal superposition method. We also do the comparison of the results from Complete Qudratic Combinatin Method and Square Root of Sum of Squares Method. Consequently, we use the acceleration spectrum of the China specification to analyze the examples in this thesis to discuss if the acceleration spectrum of Taiwan for cable-stayed bridge is too conservative.
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Forestell, Amy Dove. "Exploring the dynamics and dark halos of elliptical galaxies at large radii." 2009. http://hdl.handle.net/2152/6641.
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Dark matter is now accepted as an integral part of our universe, and galaxy dynamics have long provided the most convincing observational evidence for dark matter. Spiral galaxies have traditionally been used for these studies because of their more simple kinematics, however elliptical galaxies need to be understood as well. In this dissertation I present deep long-slit spectroscopy from the University of Texas’ Hobby-Eberly Telescope for a sample of elliptical galaxies. For a subsample of galaxies I fit axisymmetric orbit-superposition models with a range of dark halo density profiles. I find that all three galaxies modeled require a significant dark halo to explain their motions. However, the shape of the dark halo is not the expected NFW profile, but rather a profile with a flat central slope. I also discuss the galaxy masses, anisotropies, and stellar mass-to-light ratios.<br>text
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Ting, Chao-Ming. "Theoretical studies of molecule-substrate interaction at complex gold and silicon oxide surfaces using surface and cluster models." Thesis, 2020. http://hdl.handle.net/1828/12550.
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The formation and patterns of a monolayer are determined by the interplay of two fundamental interactions, adsorbate-substrate and intermolecular interactions. The binding strength between adsorbate and substrate affects the mobility of the adsorbate at the surface and the stability of the complex. The intermolecular interaction plays a significant role in the monolayer patterns on the epitaxial layer of the substrate. A monolayer can be formed either by a spontaneous self-assembly, or by fabrication via atomic-layer deposition (ALD). The physical and chemical properties of the resulting monolayer have a broad array of applications in fabricating functional materials for hydrophobic or hydrophilic surfaces, biological sensors, alternating the properties of the substrate, catalysis and forming ordered layered structures. In this dissertation, the investigation focuses primarily on the influence of the surface topology on the binding behaviour of adsorbate-surface complexes. The state of the art DFT-TS method is used to simulate the sulfur-containing amino acids at complex gold surfaces and examine the relationship between the binding strengths and the binding sites with various nearest neighbouring environments. The same method is also used to determine if a chemical reaction will take place for various catalytic silicon precursors at a silicon oxide surface.
Simulating surface chemistry using the DFT-TS method requires intensive com- puting resources, including CPU use and computing time. Another focus of this dissertation is to increase the data generating speed by reducing the size of the sim- ulated systems without altering the outcome. A relatively small gold cluster is used to study the binding behaviours of small organic molecules on the cluster. The same strategy is also used to simulate the chemical reactions between various self-catalying silicon precursors and a water molecule.<br>Graduate<br>2021-10-21