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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
71

Sezónní variabilita aktivity a promořenosti patogenem v populacích raka pruhovaného / Seasonal variation of activity and pathogen prevalence in populations of the spiny-cheek crayfish

Matasová, Klára January 2011 (has links)
The most widespread of invasive crayfish in the Czech Republic is the spiny-cheek crayfish (Orconectes limosus). It is a major disease carrier of crayfish plague, caused by the pathogen Aphanomyces astaci. The infection is lethal to European native species of crayfish. Transmission of this disease is usually associated with the spread of crayfish, which is dependent on their movement. The main aim of this work was to evaluate the differences in crayfish migratory activity in the Pšovka brook among seasons, and assess the factors that may affect it, by the use of radiotelemetry and trapping. We tested the hypothesis that crayfish use brook in the period from spring to autumn and then return back into a pond to overwinter. Furthermore, we evaluated how far from the pond crayfish migrate, and whether there is any relationship between migration and the season or water temperature. The results demonstrate that the activity varies among seasons (being strongly affected by breeding season) but in most studied periods did not significantly depend on water temperature. According to our monitoring, the spiny-cheek crayfish does not spread substantially to upstream parts of the Pšovka. Seasonal migration between the pond and the brook was monitored using two-way flow-through traps installed at the mouth of...
72

Approximations de rang faible et modèles d'ordre réduit appliqués à quelques problèmes de la mécanique des fluides / Low rank approximation techniques and reduced order modeling applied to some fluid dynamics problems

Lestandi, Lucas 16 October 2018 (has links)
Les dernières décennies ont donné lieux à d'énormes progrès dans la simulation numérique des phénomènes physiques. D'une part grâce au raffinement des méthodes de discrétisation des équations aux dérivées partielles. Et d'autre part grâce à l'explosion de la puissance de calcul disponible. Pourtant, de nombreux problèmes soulevés en ingénierie tels que les simulations multi-physiques, les problèmes d'optimisation et de contrôle restent souvent hors de portée. Le dénominateur commun de ces problèmes est le fléau des dimensions. Un simple problème tridimensionnel requiert des centaines de millions de points de discrétisation auxquels il faut souvent ajouter des milliers de pas de temps pour capturer des dynamiques complexes. L'avènement des supercalculateurs permet de générer des simulations de plus en plus fines au prix de données gigantesques qui sont régulièrement de l'ordre du pétaoctet. Malgré tout, cela n'autorise pas une résolution ``exacte'' des problèmes requérant l'utilisation de plusieurs paramètres. L'une des voies envisagées pour résoudre ces difficultés est de proposer des représentations ne souffrant plus du fléau de la dimension. Ces représentations que l'on appelle séparées sont en fait un changement de paradigme. Elles vont convertir des objets tensoriels dont la croissance est exponentielle $n^d$ en fonction du nombre de dimensions $d$ en une représentation approchée dont la taille est linéaire en $d$. Pour le traitement des données tensorielles, une vaste littérature a émergé ces dernières années dans le domaine des mathématiques appliquées.Afin de faciliter leurs utilisations dans la communauté des mécaniciens et en particulier pour la simulation en mécanique des fluides, ce manuscrit présente dans un vocabulaire rigoureux mais accessible les formats de représentation des tenseurs et propose une étude détaillée des algorithmes de décomposition de données qui y sont associées. L'accent est porté sur l'utilisation de ces méthodes, aussi la bibliothèque de calcul texttt{pydecomp} développée est utilisée pour comparer l'efficacité de ces méthodes sur un ensemble de cas qui se veut représentatif. La seconde partie de ce manuscrit met en avant l'étude de l'écoulement dans une cavité entraînée à haut nombre de Reynolds. Cet écoulement propose une physique très riche (séquence de bifurcation de Hopf) qui doit être étudiée en amont de la construction de modèle réduit. Cette étude est enrichie par l'utilisation de la décomposition orthogonale aux valeurs propres (POD). Enfin une approche de construction ``physique'', qui diffère notablement des développements récents pour les modèles d'ordre réduit, est proposée. La connaissance détaillée de l'écoulement permet de construire un modèle réduit simple basé sur la mise à l'échelle des fréquences d'oscillation (time-scaling) et des techniques d'interpolation classiques (Lagrange,..). / Numerical simulation has experienced tremendous improvements in the last decadesdriven by massive growth of computing power. Exascale computing has beenachieved this year and will allow solving ever more complex problems. But suchlarge systems produce colossal amounts of data which leads to its own difficulties.Moreover, many engineering problems such as multiphysics or optimisation andcontrol, require far more power that any computer architecture could achievewithin the current scientific computing paradigm. In this thesis, we proposeto shift the paradigm in order to break the curse of dimensionality byintroducing decomposition and building reduced order models (ROM) for complexfluid flows.This manuscript is organized into two parts. The first one proposes an extendedreview of data reduction techniques and intends to bridge between appliedmathematics community and the computational mechanics one. Thus, foundingbivariate separation is studied, including discussions on the equivalence ofproper orthogonal decomposition (POD, continuous framework) and singular valuedecomposition (SVD, discrete matrices). Then a wide review of tensor formats andtheir approximation is proposed. Such work has already been provided in theliterature but either on separate papers or into a purely applied mathematicsframework. Here, we offer to the data enthusiast scientist a comparison ofCanonical, Tucker, Hierarchical and Tensor train formats including theirapproximation algorithms. Their relative benefits are studied both theoreticallyand numerically thanks to the python library texttt{pydecomp} that wasdeveloped during this thesis. A careful analysis of the link between continuousand discrete methods is performed. Finally, we conclude that for mostapplications ST-HOSVD is best when the number of dimensions $d$ lower than fourand TT-SVD (or their POD equivalent) when $d$ grows larger.The second part is centered on a complex fluid dynamics flow, in particular thesingular lid driven cavity at high Reynolds number. This flow exhibits a seriesof Hopf bifurcation which are known to be hard to capture accurately which iswhy a detailed analysis was performed both with classical tools and POD. Oncethis flow has been characterized, emph{time-scaling}, a new ``physics based''interpolation ROM is presented on internal and external flows. This methodsgives encouraging results while excluding recent advanced developments in thearea such as EIM or Grassmann manifold interpolation.
73

Controle eletrônico das etapas do processo de planejamento de pacientes em radioterapia / Electronic control of the steps of the planning process of patients in radiotherapy

Brito, Carlos de 20 October 2017 (has links)
Em diversos serviços de radioterapia brasileiros há a premente necessidade de sistematização de processos que ainda hoje, mesmo com acesso à tecnologia da informação, é realizada manualmente. Este fato acontece com o controle dos pacientes em planejamento radioterápico onde os dados de todas as etapas do processo são inseridos em um quadro físico conforme executadas. Esses dados consistem desde o agendamento da tomografia de planejamento até a liberação do mesmo para o tratamento. O objetivo deste estudo é o desenvolvimento de um software para controle eletrônico de pacientes em processo de planejamento radioterápico, substituindo o quadro físico utilizado atualmente. Foi utilizado para este estudo a técnica de elicitação de requisitos, que resulta em um documento de requisitos que serve de base para a modelagem do sistema através de diagramas UML e modelagem conceitual do banco de dados MySql e posteriormente a utilização da técnica de mapeamento objeto relacional (MOR). A consistência nos dados permite acesso seguro e confiável à esses dados, facilita a obtenção de dados estatísticos e agiliza o processo de planejamento, já que de posse de estatísticas consistentes é possível a identificação de gargalos no processo e sua resolução com maior rapidez. O resultado deste estudo é um software e banco de dados que integra todas as informações do processo de planejamento radioterápico. / In Brazilian radiotherapy departments there is a pressing need for systematization of processes, that even today with the access of information technology is performed manually. The control of the patients in radiotherapy planning with the data of all the steps of the process are inserted in a physical board as they are executed. These data consist of scheduling since the planning tomography until the release of the patient for the treatment. The objective of this study is the development of a software for electronic control of patients in radiotherapy planning process, replacing the physical board currently used. The requirements for the elicitation technique was used for this study, which results in a requirements document that serves as the basis for modeling the system through UML diagrams and conceptual modeling of the MySql database and after using the relational object mapping technique (MOR). The data consistency allows secure and reliable access to these data, facilitates the collection of statistical data and streamlines the planning process, this consistent statistics allow the identification of limitation in the process and faster resolution. The result of this study is a software and database that integrates all the information of the radiotherapy planning process.
74

Controle eletrônico das etapas do processo de planejamento de pacientes em radioterapia / Electronic control of the steps of the planning process of patients in radiotherapy

Carlos de Brito 20 October 2017 (has links)
Em diversos serviços de radioterapia brasileiros há a premente necessidade de sistematização de processos que ainda hoje, mesmo com acesso à tecnologia da informação, é realizada manualmente. Este fato acontece com o controle dos pacientes em planejamento radioterápico onde os dados de todas as etapas do processo são inseridos em um quadro físico conforme executadas. Esses dados consistem desde o agendamento da tomografia de planejamento até a liberação do mesmo para o tratamento. O objetivo deste estudo é o desenvolvimento de um software para controle eletrônico de pacientes em processo de planejamento radioterápico, substituindo o quadro físico utilizado atualmente. Foi utilizado para este estudo a técnica de elicitação de requisitos, que resulta em um documento de requisitos que serve de base para a modelagem do sistema através de diagramas UML e modelagem conceitual do banco de dados MySql e posteriormente a utilização da técnica de mapeamento objeto relacional (MOR). A consistência nos dados permite acesso seguro e confiável à esses dados, facilita a obtenção de dados estatísticos e agiliza o processo de planejamento, já que de posse de estatísticas consistentes é possível a identificação de gargalos no processo e sua resolução com maior rapidez. O resultado deste estudo é um software e banco de dados que integra todas as informações do processo de planejamento radioterápico. / In Brazilian radiotherapy departments there is a pressing need for systematization of processes, that even today with the access of information technology is performed manually. The control of the patients in radiotherapy planning with the data of all the steps of the process are inserted in a physical board as they are executed. These data consist of scheduling since the planning tomography until the release of the patient for the treatment. The objective of this study is the development of a software for electronic control of patients in radiotherapy planning process, replacing the physical board currently used. The requirements for the elicitation technique was used for this study, which results in a requirements document that serves as the basis for modeling the system through UML diagrams and conceptual modeling of the MySql database and after using the relational object mapping technique (MOR). The data consistency allows secure and reliable access to these data, facilitates the collection of statistical data and streamlines the planning process, this consistent statistics allow the identification of limitation in the process and faster resolution. The result of this study is a software and database that integrates all the information of the radiotherapy planning process.
75

Curral de reses, Curral de almas: urbanização do sertão nordestino entre os séculos XVII e XIX / Cattle Corral, Soul\'s Corral: Urbanization of the Brazilian Northeasterner Hinterland between the 17th and 19th Centuries

Arraes, Damiao Esdras Araujo 29 March 2012 (has links)
Esta dissertação estuda a urbanização do sertão nordestino entre os séculos XVII e XIX, vinculada ao diálogo que chamamos de curral de reses e curral de almas. Curral de reses tece as questões do fenômeno urbano no interior do Nordeste açucareiro, no que dizia respeito ao papel exercido pela pecuária extensiva no povoamento, na posse da terra e no desenvolvimento de aglomerados urbanos criados ao longo dos caminhos elaborados pelo gado. As reses tangidas do litoral devassaram o hinterland nordestino, criando aqui, ali e além caminhos, desmistificando o desconhecido. Posteriormente, essas trilhas foram usadas pelas autoridades coloniais e clericais para erguer aldeamentos missioneiros - currais de almas -, visando o bem material e espiritual da Igreja e da Ordem de Cristo e a conversão dos nativos. Curral de almas busca esclarecer a ação da Igreja Católica, unida ao Estado português, no que cerce a fixação e congregação tanto do índio tapuia como dos sertanejos nômades (que \"vadiavam\" pelo território), primeiramente em aldeamentos missioneiros, depois em núcleos urbanos estrategicamente locados no território. Focalizamos o trabalho missionário dos jesuítas, capuchinhos e oratorianos na elaboração de reduções religiosas principiadas a partir da segunda metade do século XVII. Selecionamos a cidade pombalina de Oeiras (PI) e as vilas de índios Monte - Mor o Novo da América (CE) e Crato (CE) como estudos de caso, no intuito de analisar a influência da pecuária, dos caminhos do gado, das determinações provenientes de Lisboa e do papel eclesiástico da igreja em seus traçados intraurbanos. / This dissertation analyzes the urbanization process in the Brazilian northeastern hinterland between the 17th and the 18th centuries as connected to the so called Curral de Reses (Cattle Corral) and Curral de Almas (Souls\' Corral). Curral de Reses (Cattle Corral) investigates the several aspects of urbanization in the sugar-producing Northeast, relating it to the role of extensive cattle ranges in the process of population growth, to the land ownership and to the development of hamlets alongside the herding trails. The herds pushed from the coast, broke through the Brazilian northeasterner hinterland, creating hither, thither and yonder new pathways, therefore demystifying the unknown. Later in time, these trails were used by colonial and clerical authorities to start missionary settlements - \"Currais de Almas\" (Souls\' Corrals)- that aimed at the material and spiritual welfare of the Church and the Order of Christ and the conversion of the native peoples. \"Curral de Almas\" investigates the activity of the Catholic Church associated to the portuguese government as the \"Tapuia \" native people and the itinerant cowboys (who \"bummed\" around the land) settled and congregated at first in missions and later in strategically located urban centers. Another focal point has been the investigation of the missionary work of Jesuit and Capuchin friars as well as \"The Congragation of the Oratory\" in the construction of religious settlements as early as the second half of the 17th century. The town of \"Oeiras\" (PI) -created by the Marquis of Pombal- and the Indian villages \"Monte-Mor o Novo da América\" (CE) and \"Crato\"(CE) were selected as case studies, attempting to analyze the influence of cattle industry, herding trails, determinations from Lisbon and the church in the planning of the urban center.
76

Männen i Moa Martinsons Kvinnor och äppelträd

Eng, Tord January 2012 (has links)
Uppsatsen syftar till att undersöka om en nära läsning av Moa Martinsons Kvinnor och äppelträd med fokus på de manliga karaktärerna förmår öppna texten för tolkning på något nytt sätt, huvudsakligen i ett självbiografiskt perspektiv. Även den omtvistade frågan om Kvinnor och äppelträds strukturella uppbyggnad behandlas i uppsatsen.       Skildringarna av männen - Förskinnsbonden, Gamlingen, Liter-Olle med sin hund och Videbonden – visar sig leda mot en undertext, som inte frilagts i tidigare analyser. Martinsons sorg efter sina två drunknade söner tränger oupphörligt fram. Hennes kamp för att komma undan sina minnen och gå vidare avspeglas i romanen. Den svåra och kvardröjande sorgen och andra traumatiska, undanträngda händelser från det första äktenskapet kan vara en anledning till att Martinson ständigt återkom till självbiografiska skildringar i sitt författarskap. Inte mindre än nio av hennes romaner är självbiografiska.      En jämförelse av hur mor Sofi och Sally i boken behandlar de män som kommer till deras innersta rum visar sig kasta ljus över diskussionen om romanens struktur - om denna är litterärt, medvetet uppbyggd eller om de ingående berättelserna är sammanfogade mindre planmässigt, mer fristående gentemot varandra. Den figura som Ebba Witt-Brattström ser som en bekräftelse på romanens stränga, medvetna uppbyggnad, att mor Sofi förebådar sin ättling Sallys öde genom sin moderlighet ställd mot Sallys revolutionära inställning, vänds i uppsatsens perspektiv till sin motsats. Mor Sofi och hennes väninna Fredrika vänder upproriskt upp och ner på hela världen då Förskinnsbonden vågar sig fram till badstugans dörr. I motsvarande situation kapitulerar Sally och gifter sig med inkräktaren, Videbonden. Innebörden är rimligen att Witt-Brattströms tolkning av figuran faller och därmed inte kan användas som argument för något planerat samband mellan det inledande kapitlet om Sofi och de senare berättelserna om Ellen och Sally.
77

Model Order Reduction in Structural Mechanics / Coupling the Rigid and Elastic Multi Body Dynamics

Koutsovasilis, Panagiotis 06 October 2009 (has links) (PDF)
Gegenstand dieser Arbeit ist die Forschungsdisziplin, welche in der Strukturmechanik als Modellordnungsreduktion bekannt ist. Im Mittelpunkt stehen Kopplungsprozesse von starren und elastischen Mehrkörpersystemen - sowohl in theoretischer Hinsicht als auch bezüglich der praktischen Realisation im Rahmen des Finite-Elemente-Programms ANSYS und des Mehrkörpersimulationsprogramms SIMPACK. Eine Vielfalt von strukturerhaltendenMOR-Methoden wurde zum Zwecke des Überblicks dargestellt. Darüber hinaus findet sich eine Kategorisierungsmethodik in Hinsicht auf den später beschriebenen FEM-MKS-Kopplungsprozess. Die Effizienz der MOR-Methoden wird sowohl hinsichtlich der Qualität der ROM als auch bezogen auf die hierfür benötigte Rechenzeit bemessen. Aus diesem Grunde wurden etliche MOR Schemata dargelegt, mit dem Ziel, den Effizienzfaktor während der Berechnung eines ROMs zu maximieren, das heißt maximale Qualität und minimale Rechenzeit zu erzielen. Die Validierung der dynamischen ROM-Eigenschaften basiert auf der Anwendung der sogenannten Modellkorrelationskriterien. Dies wurde an vier Anwendungsbeispielen aus dem Feld der Strukturmechanik getestet: der 3D-Balkenstruktur, der UIC60-Schiene, dem Pleuel und der Kurbelwelle. Die Anwendung der diagonal perturbation-Methodik verbessert die Kondition der Steifigkeitsmatrix eines Modells, von beiden Arten von Lösungsprozeduren, d.h. direkte und iterative Verfahren, betroffen sind. Die dynamische Bewegung mechanischer MKS wird als ein Index-3-DAE-Systemformuliert und die Information über die elastischen Körper wird in Form der sogenannten Standard Input Datei in einen MKS-Code transferriert. Die Einführung des Back-projection-Ansatzes ermöglicht die weitere Verwendung bestimmter ROM-Typen, derren assoziierten physikalische Eigenschaften unangemessen definiert wurden. Zum Abschluss werden die theoretischen, modellierenden und numerischen Fortschritte der Arbeit resümiert und kombiniert im Sinne der Model Order Reduction Package Toolbox (MORPACK). Die Matlab-basierte MORPACK-Toolbox ermöglicht den FEM-MKS-Kopplungsprozess für die Verwendung von ANSYS und SIMPACK. Hierin sind ein Großteil der zuvor erläuterten Erweiterungen eingeschlossen. Mit Hilfe der zwei integrierten inneren MOR- und SID-Schnittstellen als auch der vier Anwendungsebenen wird der Import von freien oder eingespannten ROM in SIMPACK ermöglicht. / The research discipline referred to as the Model Order Reduction in structural mechanics is the topic of this Thesis. Special emphasis is given to the coupling process of rigid and elastic Multi Body Dynamics in terms of both the theoretical aspects and the practical realization within the environment of the commercial Finite Element and the Multi Body Systems software packages, ANSYS and SIMPACK respectively. In this regard, a variety of structure preserving Model Order Reduction methods is presented and a categorization methodology is provided in view of the later FEM-MBS coupling process. The algorithmic scheme of several of the MOR methods indicates the capability of generating qualitatively better Reduced Order Models than the standardized Guyan and Component Mode Synthesis approaches. The efficiency of a MOR method is measured in terms of both the quality of the ROM and the associated time required for the .computation Based on the application of the, so called, Model Correlation Criteria the efficiency of the MOR schemes is tested on four application examples originating from the area of structural mechanics, i.e. the 3D elastic solid bar structure, the UIC60 elastic rail, the elastic piston rod, and the elastic crankshaft model. Herewith, the superiority of alternative MOR schemes in comparison to Guyan or CMS methods is demonstrated in terms of the ROM?s quality and the computation time by the use of either the one-step or the two-step MOR algorithms. Numerous of the FE discretized structures suffer from the, so called, ill-conditioned properties regarding the associated stiffness matrix. On one hand, the direct solution of a MOR method might produce erroneous ROMs due to the associated truncation phenomenon and on the other hand, any kind of iterative approach suffers from vast computation times. The application of the diagonal perturbation methodology improves the condition properties of the model?s stiffness matrix and thus, both kinds of the aforementioned solution procedures are affected. The back-projection approach is introduced, which projects the ROM belonging to the Non physical subspace reduction-expansion methods category back onto the physical configuration space and thus, enabling its further usage in a MBS code, e.g. SIMPACK. Finally, the theoretical, modelling, and numerical advancements are combined in terms of the Model Order Reduction Package. The Matlab-based MORPACK toolbox enables the FEM-MBS coupling process for the ANSYS-SIMPACK utilization and herewith, several of the aforementioned enhancements are included. With the help of the two integrated inner interfaces, i.e. MOR and SID, as well as four application levels, the import into SIMPACK of alternatively free or fixed ROMs is enabled. The functionality of MORPACK is demonstrated based on two application examples, namely, the 3D elastic solid bar and the UIC60 elastic rail, the dynamic properties of which are validated prior to their import into SIMPACK.
78

Curral de reses, Curral de almas: urbanização do sertão nordestino entre os séculos XVII e XIX / Cattle Corral, Soul\'s Corral: Urbanization of the Brazilian Northeasterner Hinterland between the 17th and 19th Centuries

Damiao Esdras Araujo Arraes 29 March 2012 (has links)
Esta dissertação estuda a urbanização do sertão nordestino entre os séculos XVII e XIX, vinculada ao diálogo que chamamos de curral de reses e curral de almas. Curral de reses tece as questões do fenômeno urbano no interior do Nordeste açucareiro, no que dizia respeito ao papel exercido pela pecuária extensiva no povoamento, na posse da terra e no desenvolvimento de aglomerados urbanos criados ao longo dos caminhos elaborados pelo gado. As reses tangidas do litoral devassaram o hinterland nordestino, criando aqui, ali e além caminhos, desmistificando o desconhecido. Posteriormente, essas trilhas foram usadas pelas autoridades coloniais e clericais para erguer aldeamentos missioneiros - currais de almas -, visando o bem material e espiritual da Igreja e da Ordem de Cristo e a conversão dos nativos. Curral de almas busca esclarecer a ação da Igreja Católica, unida ao Estado português, no que cerce a fixação e congregação tanto do índio tapuia como dos sertanejos nômades (que \"vadiavam\" pelo território), primeiramente em aldeamentos missioneiros, depois em núcleos urbanos estrategicamente locados no território. Focalizamos o trabalho missionário dos jesuítas, capuchinhos e oratorianos na elaboração de reduções religiosas principiadas a partir da segunda metade do século XVII. Selecionamos a cidade pombalina de Oeiras (PI) e as vilas de índios Monte - Mor o Novo da América (CE) e Crato (CE) como estudos de caso, no intuito de analisar a influência da pecuária, dos caminhos do gado, das determinações provenientes de Lisboa e do papel eclesiástico da igreja em seus traçados intraurbanos. / This dissertation analyzes the urbanization process in the Brazilian northeastern hinterland between the 17th and the 18th centuries as connected to the so called Curral de Reses (Cattle Corral) and Curral de Almas (Souls\' Corral). Curral de Reses (Cattle Corral) investigates the several aspects of urbanization in the sugar-producing Northeast, relating it to the role of extensive cattle ranges in the process of population growth, to the land ownership and to the development of hamlets alongside the herding trails. The herds pushed from the coast, broke through the Brazilian northeasterner hinterland, creating hither, thither and yonder new pathways, therefore demystifying the unknown. Later in time, these trails were used by colonial and clerical authorities to start missionary settlements - \"Currais de Almas\" (Souls\' Corrals)- that aimed at the material and spiritual welfare of the Church and the Order of Christ and the conversion of the native peoples. \"Curral de Almas\" investigates the activity of the Catholic Church associated to the portuguese government as the \"Tapuia \" native people and the itinerant cowboys (who \"bummed\" around the land) settled and congregated at first in missions and later in strategically located urban centers. Another focal point has been the investigation of the missionary work of Jesuit and Capuchin friars as well as \"The Congragation of the Oratory\" in the construction of religious settlements as early as the second half of the 17th century. The town of \"Oeiras\" (PI) -created by the Marquis of Pombal- and the Indian villages \"Monte-Mor o Novo da América\" (CE) and \"Crato\"(CE) were selected as case studies, attempting to analyze the influence of cattle industry, herding trails, determinations from Lisbon and the church in the planning of the urban center.
79

Model Order Reduction in Structural Mechanics: Coupling the Rigid and Elastic Multi Body Dynamics

Koutsovasilis, Panagiotis 21 September 2009 (has links)
Gegenstand dieser Arbeit ist die Forschungsdisziplin, welche in der Strukturmechanik als Modellordnungsreduktion bekannt ist. Im Mittelpunkt stehen Kopplungsprozesse von starren und elastischen Mehrkörpersystemen - sowohl in theoretischer Hinsicht als auch bezüglich der praktischen Realisation im Rahmen des Finite-Elemente-Programms ANSYS und des Mehrkörpersimulationsprogramms SIMPACK. Eine Vielfalt von strukturerhaltendenMOR-Methoden wurde zum Zwecke des Überblicks dargestellt. Darüber hinaus findet sich eine Kategorisierungsmethodik in Hinsicht auf den später beschriebenen FEM-MKS-Kopplungsprozess. Die Effizienz der MOR-Methoden wird sowohl hinsichtlich der Qualität der ROM als auch bezogen auf die hierfür benötigte Rechenzeit bemessen. Aus diesem Grunde wurden etliche MOR Schemata dargelegt, mit dem Ziel, den Effizienzfaktor während der Berechnung eines ROMs zu maximieren, das heißt maximale Qualität und minimale Rechenzeit zu erzielen. Die Validierung der dynamischen ROM-Eigenschaften basiert auf der Anwendung der sogenannten Modellkorrelationskriterien. Dies wurde an vier Anwendungsbeispielen aus dem Feld der Strukturmechanik getestet: der 3D-Balkenstruktur, der UIC60-Schiene, dem Pleuel und der Kurbelwelle. Die Anwendung der diagonal perturbation-Methodik verbessert die Kondition der Steifigkeitsmatrix eines Modells, von beiden Arten von Lösungsprozeduren, d.h. direkte und iterative Verfahren, betroffen sind. Die dynamische Bewegung mechanischer MKS wird als ein Index-3-DAE-Systemformuliert und die Information über die elastischen Körper wird in Form der sogenannten Standard Input Datei in einen MKS-Code transferriert. Die Einführung des Back-projection-Ansatzes ermöglicht die weitere Verwendung bestimmter ROM-Typen, derren assoziierten physikalische Eigenschaften unangemessen definiert wurden. Zum Abschluss werden die theoretischen, modellierenden und numerischen Fortschritte der Arbeit resümiert und kombiniert im Sinne der Model Order Reduction Package Toolbox (MORPACK). Die Matlab-basierte MORPACK-Toolbox ermöglicht den FEM-MKS-Kopplungsprozess für die Verwendung von ANSYS und SIMPACK. Hierin sind ein Großteil der zuvor erläuterten Erweiterungen eingeschlossen. Mit Hilfe der zwei integrierten inneren MOR- und SID-Schnittstellen als auch der vier Anwendungsebenen wird der Import von freien oder eingespannten ROM in SIMPACK ermöglicht. / The research discipline referred to as the Model Order Reduction in structural mechanics is the topic of this Thesis. Special emphasis is given to the coupling process of rigid and elastic Multi Body Dynamics in terms of both the theoretical aspects and the practical realization within the environment of the commercial Finite Element and the Multi Body Systems software packages, ANSYS and SIMPACK respectively. In this regard, a variety of structure preserving Model Order Reduction methods is presented and a categorization methodology is provided in view of the later FEM-MBS coupling process. The algorithmic scheme of several of the MOR methods indicates the capability of generating qualitatively better Reduced Order Models than the standardized Guyan and Component Mode Synthesis approaches. The efficiency of a MOR method is measured in terms of both the quality of the ROM and the associated time required for the .computation Based on the application of the, so called, Model Correlation Criteria the efficiency of the MOR schemes is tested on four application examples originating from the area of structural mechanics, i.e. the 3D elastic solid bar structure, the UIC60 elastic rail, the elastic piston rod, and the elastic crankshaft model. Herewith, the superiority of alternative MOR schemes in comparison to Guyan or CMS methods is demonstrated in terms of the ROM?s quality and the computation time by the use of either the one-step or the two-step MOR algorithms. Numerous of the FE discretized structures suffer from the, so called, ill-conditioned properties regarding the associated stiffness matrix. On one hand, the direct solution of a MOR method might produce erroneous ROMs due to the associated truncation phenomenon and on the other hand, any kind of iterative approach suffers from vast computation times. The application of the diagonal perturbation methodology improves the condition properties of the model?s stiffness matrix and thus, both kinds of the aforementioned solution procedures are affected. The back-projection approach is introduced, which projects the ROM belonging to the Non physical subspace reduction-expansion methods category back onto the physical configuration space and thus, enabling its further usage in a MBS code, e.g. SIMPACK. Finally, the theoretical, modelling, and numerical advancements are combined in terms of the Model Order Reduction Package. The Matlab-based MORPACK toolbox enables the FEM-MBS coupling process for the ANSYS-SIMPACK utilization and herewith, several of the aforementioned enhancements are included. With the help of the two integrated inner interfaces, i.e. MOR and SID, as well as four application levels, the import into SIMPACK of alternatively free or fixed ROMs is enabled. The functionality of MORPACK is demonstrated based on two application examples, namely, the 3D elastic solid bar and the UIC60 elastic rail, the dynamic properties of which are validated prior to their import into SIMPACK.
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Process optimization of thermal modification of Chilean Eucalyptus nitens plantation wood

Wentzel, Maximilian 29 January 2019 (has links)
No description available.

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