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McCaine, Gina. "Halo orbit design and optimization." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2004. http://library.nps.navy.mil/uhtbin/hyperion/04Mar%5FMcCaine.pdf.
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Thesis (M.S. in Astronautical Engineering)--Naval Postgraduate School, March 2004.<br>Thesis advisor(s): I. Michael Ross, Don Danielson. Includes bibliographical references (p. 39-40). Also available online.
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Tolbert, Douglas Robert. "Spacecraft formation flight at sun-earth/moon libration points." Diss., Rolla, Mo. : Missouri University of Science and Technology, 2009. http://scholarsmine.mst.edu/thesis/pdf/Tolbert_09007dcc8069e8b8.pdf.
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Thesis (Ph. D.)--Missouri University of Science and Technology, 2009.<br>Vita. The entire thesis text is included in file. Title from title screen of thesis/dissertation PDF file (viewed August 14, 2009) Includes bibliographical references (p. 68-71).
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Lizy-Destrez, Stéphanie. "Operational scenarios optimization for resupply of crew and cargo of an International gateway Station located near the Earth-Moon-Lagrangian point-2." Thesis, Toulouse, ISAE, 2015. http://www.theses.fr/2015ESAE0034/document.
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Ce projet se place dans le contexte des futures missions habitées d’exploration du système solaire (avec un horizon de 2025), en respect de la feuille de route proposée par l’ISECG (International Space Exploration Coordination Group) [1]. Une nouvelle avancée serait de maintenir, à un des points de Lagrange du système Terre-Lune, en avant-poste, une station spatiale qui faciliterait l’accès vers les destinations telles que la Lune, Mars et les astéroïdes et permettrait de tester certaines technologies, notamment avant de les employer pour des missions plus lointaines. Un des principaux défis sera de maintenir en permanence et de garantir à bord la santé de l’équipage, à l’aide d’un centre médical (SMC) autonome arrimé à cette station. Se pose alors la problématique de la servitude d’une telle station, pendant la phase de déploiement (assemblage des différents modules constitutifs du centre médical) et la phase opérationnelle. Les enjeux résident, d’un point de vue global, dans la construction des scénarios opérationnels et, d’un point de vue local, la sélection de trajectoires, cherchant notamment à minimiser les incréments de vitesse (la dépense énergétique) et les temps de transport (sauvegarde des équipages). Quelles recommandations pourrait-on apporter en terme d’optimisation de trajectoire, satisfaisant des critères de dépense énergétique, durée de transport et sécurité ? Quels sont les verrous technologiques à lever pour permettre la réalisation d’une telle station spatiale? Quelles seraient les performances à viser pour les sous-systèmes critiques impliqués? Les résultats d’une telle étude permettraient d’ouvrir des perspectives de recherche et développement dans le domaine des vols habités, notamment dans le domaine du transport mais également dans l’optique d’une occupation de longue durée<br>In the context of future human space exploration missions in the solar system (with an horizon of 2025) and according to the roadmap proposed by ISECG (International Space Exploration Coordination Group) [1], a new step could be to maintain as an outpost, at one of the libration points of the Earth-Moon system, a space station. This would ease access to far destinations as Moon, Mars and asteroids and would allow to test some innovative technologies, before employing them for far distant human missions. One of the main challenges will be to maintain permanently, and ensure on board crew health thanks to an autonomous space medical center docked to the proposed space station, as a Space haven. Then the main problem to solve is to manage the station servitude, during deployment (modules integration) and operational phase. Challenges lie, on a global point of view, in the design of the operational scenarios and, on a local point of view, in trajectories selection, so as to minimize velocity increments (energy consumption) and transportation duration (crew safety). Which recommendations could be found out as far as trajectories optimization is concerned, that would fulfill energy consumption, transportation duration and safety criterion? What would technological hurdles be to rise for the building of such Space haven? What would be performances to aim at for critical sub-systems? Expected results of this study could point out research and development perspectives for human spaceflight missions and above all, in transportation field for long lasting missions.Thus, the thesis project, presented here, aims at from global system life-cycle decomposition, to identify by phase operational scenario and optimize resupply vehicle mission. The main steps of this project consist in:- Bibliographical survey, that covers all involved disciplines like mission analysis (Astrodynamics, Orbital mechanics, Orthography, N-Body Problem, Rendezvous…), Applied Mathematics, Optimization, Systems Engineering….- Entire system life-cycle analysis, so as to establish the entire set of scenarios for deployment and operations (nominal cases, degraded cases, contingencies…) and for all trajectories legs (Low Earth Orbit, Transfer, Rendezvous, re-entry…)- Trade-off analysis for Space Station architecture- Modeling of the mission legs trajectories- Trajectories optimizationThree main scenarios have been selected from the results of the preliminary design of the Space Station, named THOR: the Space Station deployment, the resupply cargo missions and the crew transportation. The deep analysis of those three main steps sorted out the criticality of the rendezvous strategies in the vicinity of Lagrangian points. A special effort has been set on those approach maneuvers. The optimization of those rendezvous trajectories led to consolidate performances (in term of energy and duration) of the global transfer from the Earth to the Lagrangian point neighborhood and return. Finally, recommendations have been deduced that support the Lagrangian points importance for next steps of Human Spaceflight exploration of the Solar system
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Salazar, Francisco Javier Tipán. "Deployment and maintenance of a satellite formation flight around L4 and L5 Lagrangian points in the earth-moon system based on low cost strategies." Instituto Nacional de Pesquisas Espaciais (INPE), 2012. http://urlib.net/sid.inpe.br/mtc-m19/2012/11.22.12.22.
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Este trabalho está focado em métodos de transferência a partir de uma órbita circular ao redor da Terra até órbitas periódicas ao redor dos pontos Lagrangianos \textit{L}$_{4}$ e \textit{L}$_{5}$ no sistema Terra-Lua, com aplicações para colocar vários satélites em vôo de formação. Os pontos Lagrangianos \textit{L}$_{4}$ e \textit{L}$_{5}$ estão localizados a 60 graus acima e embaixo da linha que conecta a Terra com a Lua e formam com estes dois corpos um triângulo equilátero. Estes pontos Lagrangianos são estáveis pela relação de massa entre a Terra e a Lua. Devido à sua distância, radiações eletromagnéticas que proveem da Terra e chegam até eles são substancialmente atenuadas. Dessa maneira, estes pontos Lagrangianos representam posições extraordinárias para colocar observatórios astronômicos. Inspirados nos recentes resultados em manobras assistidas por gravidade, os métodos de transferência implementados neste trabalho usam o campo gravitacional da Lua para atingir os pontos Lagrangianos. Nós aplicamos três diferentes técnicas para intersectar a esfera de influência da Lua: Transferências de Mínima Energia, Trajetórias G e Órbitas Caóticas, e mostramos que existem novas trajetórias alternativas para chegar até nosso objetivo. Nós encontramos vantagens em relação à Transferência de Hohmann tais como gasto menor de combustível e a possibilidade de usar o mesmo lançador para enviar os satélites até os pontos \textit{L}$_{4}$ e \textit{L}$_{5}$. O trabalho também apresenta um estudo das geometrias ao redor das órbitas periódicas centradas em \textit{L}$_{4}$ com boas propriedades para vôos em formação. Nós consideramos a possibilidade da existência de regiões com aceleração radial relativa zero com respeito à trajetória nominal. As simulações numéricas mostram que para evitar grandes variações das distâncias mutuas entre os satélites, a formação tem que estar localizada não ao longo da direção de aceleração radial relativa nula senão ao longo da direção de aceleração radial relativa mínima. Este trabalho está feito utilizando o modelo Circular Restrito de Três Corpos, considerando só o movimento no plano da órbita dos sistema Terra-Lua.<br>This thesis focuses on transfer methods from a circular parking orbit around the Earth to periodic orbits around the Lagrangian points \textit{L}$_{4}$ and \textit{L}$_{5}$ in the Earth-Moon system, with applications to place multiple satellites in formation flying. Lagrangian points \textit{L}$_{4}$ and \textit{L}$_{5}$ lie at 60 degrees ahead of and behind Moon in its orbit with respect to the Earth and form an equilateral triangle with the base of the line defined by those two bodies. These Lagrangian points are stable for the Earth-Moon mass ratio. Because of their distance, electromagnetic radiations from the Earth arrive on them substantially attenuated. As so, these Lagrangian points represent remarkable positions to host astronomical observatories. Inspired by the recent results in gravity assist maneuvers, the transfer methods implemented in this work use the gravita-tional field of the Moon to reach the Lagrangian points. We apply three different techniques to intersect the lunar sphere of influence: Minimum Energy Transfers, Trajectories G and Chaotic Orbits, and prove that there exist new alternative trajectories to reach our target. We find advantages over the Hohmann transfer such as less fuel spent and the possibility using only one rocket launcher to deliver spacecrafts to \textit{L}$_{4}$ and \textit{L}$_{5}$. The thesis also presents a study of geometries around periodic orbits centered at \textit{L}$_{4}$ with good properties for formation flying. We consider the possible existence of regions of zero relative radial acceleration with respect to the nominal trajectory. Numerical simulations show that to avoid large variations of the mutual distances between the spacecrafts, the formation flying must be arranged not along the direction of zero relative radial acceleration but along the direction of minimum relative radial acceleration. This work is done in the force model defined by the Circular Restricted Three Body Problem, considering only the motion on the plane of the orbit of the Earth-Moon system.
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Belati, Edmarcio Antonio. "Sensibilidade em fluxo de potência ótimo." Universidade de São Paulo, 2003. http://www.teses.usp.br/teses/disponiveis/18/18133/tde-07102015-154129/.
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Neste trabalho propomos uma abordagem para a resolução do problema de Fluxo de Potência Ótimo (FPO) perturbado. A metodologia consiste na obtenção da solução ótima para o problema inicial via um programa de FPO, e na utilização de sensibilidade para estimar novas soluções depois de ocorridas algumas perturbações no problema. Essas perturbações são variações de carga em uma ou mais barras do sistema. A técnica de sensibilidade está baseada nas informações de segunda ordem e nas condições de otimalidade. A obtenção da solução após ocorrerem perturbações no sistema é direta e não necessita de parâmetros iniciais e de correção, como penalidade e barreira, utilizados nos programas de FPO convencionais. Os resultados numéricos apresentados evidenciam o potencial desta metodologia para resolução do problema de FPO perturbado.<br>An approach to solve the perturbated Optimal Power Flow (OPF) problem is proposed in this study. The methodology consists in obtaining the optimal solution for the initial problem via a program of OPF, and using sensitivity to estimate new solutions after the occurrence of some perturbations in the problem. These perturbations consist in load variations in some buses of the system. The sensitivity technique is based on both the information of second order and otimality conditions. The computation of the solutions after the occurrence of perturbations in the system does not depend of initial and correction parameters such as penalty and barrier used in the conventional OPF programs. The numerical results demonstrate the potential of this methodology for the solution of the perturbated OPF problem.
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Mitra, Subhadeep. "Particle filtering with Lagrangian data in a point vortex model." Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/72873.
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Thesis (S.M.)--Massachusetts Institute of Technology, Computation for Design and Optimization Program, 2012.<br>Cataloged from PDF version of thesis.<br>Includes bibliographical references (p. 131-138).<br>Particle filtering is a technique used for state estimation from noisy measurements. In fluid dynamics, a popular problem called Lagrangian data assimilation (LaDA) uses Lagrangian measurements in the form of tracer positions to learn about the changing flow field. Particle filtering can be applied to LaDA to track the flow field over a period of time. As opposed to techniques like Extended Kalman Filter (EKF) and Ensemble Kalman Filter (EnKF), particle filtering does not rely on linearization of the forward model and can provide very accurate estimates of the state, as it represents the true Bayesian posterior distribution using a large number of weighted particles. In this work, we study the performance of various particle filters for LaDA using a two-dimensional point vortex model; this is a simplified fluid dynamics model wherein the positions of vortex singularities (point vortices) define the state. We consider various parameters associated with algorithm and examine their effect on filtering performance under several vortex configurations. Further, we study the effect of different tracer release positions on filtering performance. Finally, we relate the problem of optimal tracer deployment to the Lagrangian coherent structures (LCS) of point vortex system.<br>by Subhadeep Mitra.<br>S.M.
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Arnaud, Marie-Claude. "Points périodiques et tores lagrangiens invariants des difféomorphismes symplectiques." Paris 7, 1990. http://www.theses.fr/1990PA077111.
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On montre que les dimensions elliptiques des points fixes des diffeomorphismes exacts symplectiques generiques du fibre cotangent du tore de dimension n qui sont proches de diffeomorphismes completement integrables a torsion non degeneree verifient un analogue des inegalites de morse, mais que ce n'est pas le cas pour les dimensions hyperboliques. A l'aide du theoreme de birkhoff-lewis, on applique ces resultats pour decrire les points periodiques qui s'accumulent sur les points fixes elliptiques de diffeomorphismes symplectiques generiques et au moins quatre fois differentiables. Ensuite, on montre le theoreme suivant: soit f un diffeomorphisme symplectique infiniment differentiable et generique d'une variete symplectique et compacte de dimension quatre. Alors, f n'a pas de tore invariant lagrangien de classe infinie contenant un point periodique. Pour cela, on applique des resultats dus a f. Oliveira et d. Pixton concernant les intersections heteroclines
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Liot, Olivier. "Approches innovantes en convection thermique turbulente. Influence des rugosités et étude Lagrangienne." Thesis, Lyon, École normale supérieure, 2015. http://www.theses.fr/2015ENSL1054/document.
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Lors de cette thèse nous avons étudié le phénomène de convection thermique turbulente. La compréhension des mécanismes du flux thermique induit est encore un défi. Dans cette optique, deux approches innovantes ont été utilisées. La première a consisté en une approche Lagrangienne. Dans un premier temps, nous avons immergé une particule instrumentée munie de capteurs de température. Sa vitesse a été mesurée simultanément afin de calculer le flux thermique local transporté. En comparant les mesures effectuées à des simulations numériques et à des mesures Eulériennes, la pertinence de cette méthode a été révélée. Nous avons ensuite ensemencé l'écoulement avec des particules de diamètre inférieur à l'échelle dissipative du système. Nous avons alors pu effectuer les suivre en 3D et nous intéresser aux statistiques turbulentes, ainsi qu'à la dispersion de paires. Nous avons ensuite étudié une configuration où la plaque du bas comporte des rugosités contrôlées. Il est reconnu que cela amène une augmentation du transfert thermique supérieure à celle reliée à l'augmentation de surface. Nous avons mis en évidence des mécanismes possibles qui expliquent ce phénomène. Des mesures thermométriques dans une cellule remplie d'eau ainsi que des mesures vélocimétriques dans une cellule six fois plus grande remplie d'air ont permis d'observer un changement radical de la structure des couches limites au voisinage des rugosités, notamment l'apparition d'une couche limite turbulente. Ces mesures ont été accompagnées de mesures de vitesse de l'écoulement global qui ont révélé une augmentation drastique des fluctuations de vitesse ainsi que l'apparition d'un nouveau régime de turbulence<br>In this work, turbulent thermal convection is studied. Undestanding the mechanisms of induced thermal flux is still a challenge. In this context we used two innovative approaches.The first one consists in a Lagrangian approach. An instrumented particle, designed for temperature measurements, is immersed in the flow. The simultaneous measurement of the temperature view from the particle and its velocity allowsto obtain local Lagrangian heat flux. By comparing these measurements with numerical simulation and Eulerian investigations we can assert the relevance of this method. Then we seeded the flow with particles whose diameter is smaller than the dissipative scale of the system. We performed 3D tracking to access to turbulent statistics and pair dipersion.On the other hand we study a configuration with controlled roughness on the bottom plate. It is well-known that it leads to thermal flux enhancement higher than the one linked to the surface increasing. We bring out possible mechanisms to explain this phenomenon. Thermometric measurements in water-filled cell and anemometric measurements in a six-time larger air-filled cell point out a dramatic change of the boundary layers structure close to roughness. Particularly a turbulent viscous boundary layer appears. Theses investigations are supplemented by velocity measurements of the global flow and reveal a large increase of velocity fluctuations and the appearance of a new turbulence regime
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Oberti, Pascal. "Satellites lagrangiens de Téthys et Dioné : réduction d'observations et théorie du mouvement." Observatoire de Paris, 1988. https://hal.archives-ouvertes.fr/tel-02095280.
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Découverts pendant le passage de la Terre dans le plan des anneaux de saturne, en 1980, ces satellites faibles se trouvent près des points de Lagrange équilatéraux de Téthys et Dioné. Quelques années d'observations ont fourni la base de l'étude de leur mouvement, donnant des positions précises sur lesquelles il est possible d'ajuster des simulations numériques. Celles-ci ont, à leur tour, aidé à calibrer un modèle analytique du mouvement permettant une bonne prédiction des positions de ces satellites.
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Wong, Brian 1978. "Dynamics of a multi-tethered satellite system near the sun-earth Lagrangian point." Thesis, McGill University, 2003. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=80151.
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This paper examines the dynamics of a tether connected multi-spacecraft system, arranged in a wheel-spoke configuration, in the vicinity of the L 2 Lagrangian point of the Sun-Earth system. First, the equations of motion of a N-body system are obtained and equilibrium configurations of the system are determined and small motions about one of these configurations are analyzed. Then, a numerical analysis of the free tether libration is carried out for a three-mass case when the system is near L2 and the parent mass is assumed to be in a halo orbit of different sizes. Finally, a set of control goals are defined and a time domain state feedback control system is integrated into the numerical model. The performance of the control system is tested under different conditions.
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García, de Herreros Miciano María. "Feasibility study of the implementation of a space sunshade near the first Lagrangian point." Thesis, KTH, Rymdteknik, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-280140.
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The lack of strong measures to avoid the possible fatal consequences of global warming is pushing researchers to look for other alternatives such as geoengineering.Within geoengineering, this study focuses on the space based solar radiation management methods. More precisely, the project evaluates the feasibilityof implementing a space sun shade near the first Lagrangian point in the Sun-Earth system within a thirty year period time from now. The study isstructured in three main blocks: spacecraft configuration, trajectory definition and launch. An analysis looking at the minimum cost system was carried out,starting with the definition of the mass and size of spacecraft. Furthermore, an optimization of the trajectory was developed in order to minimize the traveltime to the vicinity of the Lagrangian point. The shades will be formed by swarms of 10 000m2 solar sails that will cover an area of 6:3 x 1012 m2 witha total mass of around 5:7 x 1010 kg. The sails will be injected into a LEO and will start a trajectory to the vicinity of the first Lagrangian point that willtake around 2.3 years. The total cost of the project is approximated to be 10 trillion dollars. The mission appears to be feasible from a technological pointof view, with some development needed in the attitude control subsystem. The main challenge will be the launch of all the spacecraft. A space mission of thisdimensions has never been attempted before so it will require a big advance from the launch vehicle industry.<br>Bristen på åtgärder för att undvika de konsekvenser som den globala uppvärmingen leder till, har drivit forskare att leta efter alternativa lösningar, varav geoengineering är en av dem. Denna studie fokuserar på rymdbaserade strålhanteringsmetoder, mer specifikt på hur huruvida implementationer av solparasoller nära Lagrangepunkten L1 i sol-jord-systemet är möjlig eller ej. Studien är strukturerad i tre huvudsakliga block: rymdskeppskonfiguration, banadefinition och uppskjutning. Med målet att minimera kostnaderna, definierades rymdskeppets utforming, massa och storlek. Vidare så, optimerades vägen till närheten av L1 med avseende på att minimera tiden. Solparasollerna kommer vara placerade i svärmar med en area på 10 000m2 vardera, totalt kommer solparasollerna att täcka en yta av 6:3 x 1012 m2 med en total massa på 5:7 x 1010 kg. Solparasollerna kommer skjutas upp till LEO och därefter starta sin resa till närheten av L1, vilket kommer ta cirka 2.3 år. Totala kostanden för projektet uppskattas till 10 billioner dollar. Efter genomförd studie visades projektet vara genomförbart sett från en teknisk synvinkel, men vidare studier behövs göras för att utveckla och fastställa styrsystemet. Huvudutmaningen kommer att vara uppskjutningen av rymdskeppen, då det kräver stora framsteg och utveckling inom rymdindustrin.
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Pereira, Aguinaldo Aparecido. "O método da função Lagrangiana barreira modificada/penalidade." Universidade de São Paulo, 2007. http://www.teses.usp.br/teses/disponiveis/18/18154/tde-14032008-155744/.
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Neste trabalho propomos uma abordagem que utiliza o método de barreira modificada/penalidade para a resolução de problemas restritos gerais de otimização. Para isso, foram obtidos dados teóricos, a partir de um levantamento bibliográfico, que explicitaram os métodos primal-dual barreira logarítmica e método de barreira modificada. Nesta abordagem, as restrições de desigualdade canalizadas são tratadas pela função barreira de Frisch modificada, ou por uma extrapolação quadrática e as restrições de igualdade do problema através da função Lagrangiana. A implementação consiste num duplo estágio de aproximação: um ciclo externo, onde o problema restrito é convertido em um problema irrestrito, usando a função Lagrangiana barreira modificada/penalidade; e um ciclo interno, onde o método de Newton é utilizado para a atualização das variáveis primais e duais. É apresentada também uma função barreira clássica extrapolada para a inicialização dos multiplicadores de Lagrange. A eficiência do método foi verificada utilizando um problema teste e em problemas de fluxo de potência ótimo (FPO).<br>In this paper, we propose an approach that utilizes the penalty/modified barrier method to solve the general constrained problems. On this purpose, theoretical data were obtained, from a bibliographical review, which enlightened the logarithmic barrier primal-dual method and modified barrier method. In this approach, the bound constraints are handled by the modified log-barrier function, or by quadratic extrapolation and the equality constraints of the problem through Lagrangian function. The method, as implemented, consists of a two-stage approach: an outer cycle, where the constrained problem is transformed into unconstrained problem, using penalty/modified barrier Lagrangian function; and an inner cycle, where the Newton\'s method is used for update the primal and dual variables. Also, it is presented a classical barrier extrapolated function for initialization of Lagrange multipliers. The effectiveness of the proposed approach has been examined by solving a test problem and optimal power flow problems (OPF).
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Corro, Caio. "Lagrangian Based Approaches for Lexicalized Tree Adjoining Grammar Parsing." Thesis, Sorbonne Paris Cité, 2018. http://www.theses.fr/2018USPCD051.
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Ces dernières années, des méthodes issues de l'optimisation combinatoire ont été appliquées avec succès pour résoudre des problèmes algorithmiques difficiles en Traitement Automatique des Langues (TAL). Nous suivons cette méthodologie dans le cadre de l'analyse syntaxique avec des Grammaires d'Arbres Adjoints Lexicalisés; Plus précisément, un problème d'analyse est d'abord réduit à un problème de sélection de sous-graphe. Ensuite nous formulons ce dernier sous forme de Programme Linéaire en Nombres Entiers. Beaucoup d'algorithmes ont été proposés pour ces formulations. Nous nous concentrons sur la Relaxation Lagrangienne qui a reçu beaucoup d'attention de la part de la communauté du TAL. La particularité de notre méthode réside dans le fait que nos algorithmes résolvent des problèmes généraux et peuvent donc être testés sur différentes données<br>In linguistics and Natural Language Processing (NLP), syntax is the studyof the structure of sentences in a given language. Two approaches have mainlybeen considered to describe them: dependency structures and phrase-structures.A dependency links a pair of words together with its relation type whereas aphrase-structure describe a sentence by means of a hierarchy of word sets calledconstituents. In this thesis, we focus on phrase-structure parsing, that is thecomputation of the constituency structure of a given sentence. Context-FreeGrammars (CFGs) have been widely adopted by the NLP community due totheir simplicity and the low complexity of their parsing algorithms. However,CFGs are too limited in order to describe all phenomena observed in naturallanguage structures. Therefore, Lexicalized Tree Adjoining Grammars (LTAGs)have been widely studied as a plausible alternative, among others. They aremore expressive than CFGs but can also be parsed in polynomial time. Unfortunately,the best known algorithm has a O(n7) time complexity with n thelength of the input sentence. Thus, in practice most algorithms are based ongreedy methods which require fairly strong independence assumptions. Themain approach in the literature, called supertagging, lters the search space ina pre-processing step while ignoring long distance relationships, one of the mainmotivation for LTAGs.In the past years, combinatorial optimization techniques have been successfullyapplied to computationally challenging NLP tasks. We follow this line ofwork in the case of LTAG parsing. More precisely, in our setting, a given NLPproblem is reduced to a subgraph selection problem. As such, it has a genericform which may interest other research communities. Then we formulate thegeneric graph problem as an Integer Linear Program. Integer Linear Programinghas been widely studied and many optimization methods exist. We focus onLagrangian relaxation which previously received much attention from the NLPcommunity. Interestingly, the proposed algorithms can be parametrized to Et arange of different data without impacting eciency.Our erst contribution is a novel pipeline for LTAG parsing. Contrary tothe supertagging approach, we propose a pre-processing step which takes intoaccount relationships between words: well-nested dependency parsing with 2-bounded block degree. An algorithm with a O(n7) time complexity has beenproposed for this problem in the literature, which is similar to the standardLTAG parser complexity. In order to tackle the complexity challenge, we showthat it can be reduced to a subgraph selection problem which can be expressed23via a generic ILP. With our algorithm, the well-nested constraint can easily betoggled o and the block degree bound can be changed. Thus, as an example,it can be used for parsing problems related to other lexicalized grammars. Weexperiment on several problems showing the emciency and usefulness of ourmethod.Our second contribution is a novel approach for discontinuous constituentparsing. We introduce a variant of LTAG for this task. Parsing is then equivalentto the joint tagging and non-projective dependency parsing problem. Weshow that it can be reduced to the Generalized Maximum Spanning Arborescenceproblem which has been previously studied in the combinatorial optimizationliterature. A novel resolution algorithm based on Lagrangian relaxation isproposed. We experiment on two standard discontinuous constituent datasetsand obtain state-of-the-art results alongside competitive decoding speed
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Hosein, Falahaty. "Enhanced fully-Lagrangian particle methods for non-linear interaction between incompressible fluid and structure." Kyoto University, 2018. http://hdl.handle.net/2433/235070.
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Ramirez, Viviana Analia 1976. "Sistemas ponto de sela com uma aplicação a aceleração do Lagrangiano Aumentado." [s.n.], 2008. http://repositorio.unicamp.br/jspui/handle/REPOSIP/306439.
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Orientador: Roberto Andreani<br>Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Matematica, Estatistica e Computação Cientifica<br>Made available in DSpace on 2018-08-10T22:54:25Z (GMT). No. of bitstreams: 1
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Previous issue date: 2008<br>Resumo: Os sistemas ponto de sela surgem em uma grande quantidade de áreas de investiga¸c¿ao, como física, química, engenharia, reconstrução de imagens, etc. Portanto, s¿ao objeto de pesquisa, tanto as propriedades presentes neles como os métodos utilizados para a sua resolução. Diversos métodos foram desenvolvidos dependendo das características do sistema, alguns deles com a propriedade de preservar a estrutura da matriz do sistema. Neste trabalho utilizamos umo destes métodos para melhorar a precisão obtida pelo método ALGENCAN (Lagrangiano Aumentado usando GENCAN) em problemas de Programação Não Linear (PNL). Este método é muito robusto, ele obtém uma boa aproximação da solução com poucas iterações, mas perto da solução não consegue obter uma precisão muito exigente. Para melhorar esta precisão, aplicamos o método de Newton a um sistema KKT reduzido no ponto obtido por ALGENCAN, gerando um sistema ponto de sela. Para esta implementação utilizamos o método conhecido como fatoração LDLT , escolhido por sua propriedade de preservar a estrutura esparsa do sistema<br>Abstract: Saddle point systems arise in wide areas of research fields like physics, chemistry and engineering and images reconstructions, etc. Then, the properties of these systems and solving methods have been subjects of intense study in the last years. Depending upon the system properties, several methods were developed; some of these, exhibit the property of preserving the matrix structure system, like the sparsity. In this work, we have used one of these methods to improve the accuracy by using ALGECAN (Augmented Lagrangian using GENCAN) applied to Non-linear Programming (NLP) problems. This is a robust method which helps to get a good approximation to the solution. However, in several cases, it is not possible to get the desired accuracy. In order to improve the precision, we have applied Newton¿s method in a reduced KKT system, starting from a point given by ALGENCAN, which is a saddle point. We employ the so called LDLT factorization in order to implement Newton¿s method, which give us better accuracy<br>Mestrado<br>Otimização<br>Mestre em Matemática Aplicada
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Dufour, Frédéric. "Développements de la méthode des éléments finis avec des points d'intégration Lagrangiens : applications à la géomécanique." Phd thesis, Ecole centrale de nantes - ECN, 2002. http://tel.archives-ouvertes.fr/tel-00334013.
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Beaucoup de modélisations numériques dans les domaines de la géophysique, du génie civil et du génie mécanique nécessitent la prise en compte de grandes transformations sur des matériaux avec des comportements allant du fluide visqueux au solide élastique, avec ou sans microstructure granulaire ou stratifiée, en passant par des matériaux bi-phasiques. Une nouvelle méthode numérique, intitulée méthode des éléments finis avec des points d'intégration Lagrangiens (MEFPIL), a été développée pour répondre à ce cahier des charges. Elle est basée sur une grille Eulérienne d'éléments finis dont les points intégrations sont des particules Lagrangiennes qui transportent dans leur mouvement les propriétés matériaux et les variables de temps. Ainsi, les limites vers les grandes transformations sont abolies, tout en transportant l'historique de la matière. Le suivi implicite des interfaces matériaux permet aussi de modéliser les interactions fluide-solide en attribuant des propriétés rhéologiques contrastées aux particules en différents points de l'espace. Ce travail a démontré que des contraintes sur le nombre et le poids numérique des points d'intégration, sont nécessaires pour obtenir de bons résultats dans des cas tests. A cause du traitement des grandes transformations sous forme incrémentale, cette méthode impose une attention particulière lors du développement et de l'implantation de nouvelles lois de comportement. Lors de ce travail, la théorie de Cosserat, la viscoélasticité, des modèles non linéaires et l'anisotropie, éventuellement couplée avec la théorie de Cosserat, ont été implantés pour répondre à des besoins précis lors de la modélisation de phénomènes géophysiques et des procédés de mise en forme de matériaux. La MEFPIL a démontré sa capacité dans la modélisation des écoulements de matériaux divers en grandes transformations et laisse entrevoir un grand potentiel pour de futures applications.
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Silva, Alysson Alexander Naves. "Simulação numérica de escoamentos bidimensionais com superfícies livres e linhas de contato dinâmicas." Universidade de São Paulo, 2010. http://www.teses.usp.br/teses/disponiveis/55/55134/tde-22062010-145307/.
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Um método lagrangeano-euleriano arbitrário para a resolução de escoamentos dominados por tensão superficial é apresentado neste trabalho. Tais escoamentos são importantes em muitas aplicações, especialmente em canais capilares que frequentemente aparecem em escoamentos em microescala. A resolução deste tipo de escoamento apresenta vários desafios que são abordados neste trabalho. O escoamento é resolvido somente para a fase líquida, com condições de contorno apropriadas para a superfície livre que delimita o líquido e o gás, que é representada por arestas e vértices da malha computacional. Esta se move e se deforma, sendo que sua qualidade é mantida sob controle para não degradar a solução numérica. As equações de Navier-Stokes são discretizadas pelo método de elementos finitos em um referencial arbitrário. O método de incorporação dos efeitos de tensão superficial e linha de contato é explicado em detalhes. Validações comprovam a precisão do método proposto, com comparações através de soluções pseudo-analíticas para casos simples. Finalmente alguns resultados sobre escoamentos em capilares são apresentados<br>An arbitrary lagrangian-eulerian finite element method to solve surface tension dominated flows is presented. Such flows are important in many applications, particularly in capillary channels, that appear in microscale flows. The resolution of such flows presents several challenges that are addressed in this work. The flow is solved only in the liquid phase, and proper boundary conditions are applied on the free-surface, bounding the liquid and gas, which is explicitly represented by vertices and edges of the computational mesh. The mesh is moved and deformed, but its quality is kept under control in order to control errors in the numerical solution. The Navier-Stokes equations are discretized by standard Galerkin finite element method in an arbitrary reference. Details of the computation of surface tension and contact line effects are presented. The methodology is validated for a number of simple test cases against known pseudo-analytical solutions, and numerical results are presented, showing the robustness and accuracy of the methodology. Finally, some results about surface-tension-driven flows in capillaries are presented
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Kuhlmann, Renke [Verfasser], Christof [Akademischer Betreuer] Büskens, Christof [Gutachter] Büskens, and Philip E. [Gutachter] Gill. "A Primal-Dual Augmented Lagrangian Penalty-Interior-Point Algorithm for Nonlinear Programming / Renke Kuhlmann ; Gutachter: Christof Büskens, Philip E. Gill ; Betreuer: Christof Büskens." Bremen : Staats- und Universitätsbibliothek Bremen, 2018. http://d-nb.info/1174669705/34.
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Sousa, Vanusa Alves de. "Resolução do problema de fluxo de potência ótimo reativo via método da função lagrangiana barreira modificada." Universidade de São Paulo, 2006. http://www.teses.usp.br/teses/disponiveis/18/18133/tde-18082006-115009/.
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Este trabalho propõe uma abordagem que utiliza uma associação dos métodos de barreira modificada e de pontos interiores primal-dual para a resolução do problema de fluxo de potência ótimo (FPO) reativo. Para isso, foi realizado um levantamento bibliográfico que explicitou os conceitos de otimização aplicados ao sistema estático de energia elétrica e os métodos dual-Lagrangiano, Newton-Lagrangiano, primal-dual barreira logarítmica e de barreira modificada. Na abordagem proposta, as restrições canalizadas são desmembradas em duas desigualdades. Estas são transformadas em igualdades a partir do acréscimo de variáveis de folga ou de excesso, as quais são relaxadas e tratadas pela função barreira modificada. Associa-se a esse problema uma função Lagrangiana. O sistema de equações resultantes das condições de estacionaridade da função Lagrangiana foi resolvido pelo método de Newton. Na implementação computacional foram usadas técnicas de esparsidade. Os sistemas elétricos de potência utilizados para verificar a eficiência da abordagem proposta na solução do problema de FPO reativo em três tipos de testes foram o de 3 barras, os do IEEE 14, 30, 118, 162 e 300 barras, o equivalente CESP 440 kV com 53 barras e o equivalente brasileiro sul-sudeste com 787 barras<br>This work proposes an approach that uses an association of the methods of modified barrier and primal-dual interior points for the resolution of the reactive optimal power flow (OPF) problem. On this purpose, a bibliographical review was accomplished, which enlightened the optimization concepts applied to the static system of electrical energy and the methods dual-Lagrangian, Newton-Lagrangian, primal-dual logarithmic barrier and modified barrier. In this approach, the bounded constraints are transformed in equalities by adding the non-negative slack variables. Those slack variables are relaxed and handled by the modified barrier function. A Lagrangian function is associated to this problem. The equation sets generated by the first-order necessary conditions of the Lagrangian function, were solved by Newton's method. In the computational implementation, sparsity techniques were used. The electric systems used to verify the efficiency of the approach proposed in the solution of the reative OPF problem in three types of tests were of the 3, IEEE 14, 30, 118, 162 and 300 buses, equivalent CESP 440 kV with 53 buses and the equivalent brazilian south-southeast with 787 buses
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Fernandes, Camila de Freitas. "NFDNA - um algoritmo para otimização não convexa e não diferenciável." Universidade Federal de Juiz de Fora, 2016. https://repositorio.ufjf.br/jspui/handle/ufjf/1837.
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Previous issue date: 2016-04-08<br>CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior<br>Neste trabalho estudamos um algoritmo para solução de problemas de otimização irrestrita
com funções não necessariamente convexas ou diferenciáveis, denominado Nonsmooth
Feasible Direction Nonconvex Algorithm - NFDNA, e fazemos uma aplicação deste algoritmo
que consistiu em utilizá-lo como subrotina de um outro algoritmo chamado Interior
Epigraph Direction (IED) method. O IED, desenvolvido para resolver problemas de otimização
não convexa, não diferenciável mas com restrições, utiliza Dualidade Lagrangeana
que requer a minimização da função Lagrangeana. A eficiência do IED depende fortemente
de tal minimização. Como aplicação, substituímos a rotina fminsearch do Matlab, utilizada
originalmente pelo IED, pelo NFDNA. Mostramos através da solução de problemas teste
que a performance do IED foi mais eficiente com a utilização do NFDNA.<br>In this work we study an algorithm for solving unsconstrained, not necessarily convex
or differentiable optimization problems called Nonsmooth Feasible Direction Nonconvex
Algorithm - NFDNA. We also employ this algorithm as a subroutine of the Interior
Epigraph Directions (IED) method. The IED method, devised for solving constrained,
nonconvex and nonsmooth optimization problems uses Lagrangean Duality which requires
the minimization of the Lagrangean function. The effectiveness of the IED depends
strongly on the Lagrangean function minimization. As an application, we replace the
Matlab routine fminsearch, originally used by IED, with NFDNA. We show through the
solution of test problems that the IED performance is more efficient by employing NFDNA.
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Nicholson, John Corbett. "Design of a large-scale constrained optimization algorithm and its application to digital human simulation." Diss., University of Iowa, 2017. https://ir.uiowa.edu/etd/5583.
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A new optimization algorithm, which can efficiently solve large-scale constrained non-linear optimization problems and leverage parallel computing, is designed and studied. The new algorithm, referred to herein as LASO or LArge Scale Optimizer, combines the best features of various algorithms to create a computationally efficient algorithm with strong convergence properties. Numerous algorithms were implemented and tested in its creation. Bound-constrained, step-size, and constrained algorithms have been designed that push the state-of-the-art. Along the way, five novel discoveries have been made: (1) a more efficient and robust method for obtaining second order Lagrange multiplier updates in Augmented Lagrangian algorithms, (2) a method for directly identifying the active constraint set at each iteration, (3) a simplified formulation of the penalty parameter sub-problem, (4) an efficient backtracking line-search procedure, (5) a novel hybrid line-search trust-region step-size calculation method. The broader impact of these contributions is that, for the first time, an Augmented Lagrangian algorithm is made to be competitive with state-of-the-art Sequential Quadratic Programming and Interior Point algorithms.
The present work concludes by showing the applicability of the LASO algorithm to simulate one step of digital human walking and to accelerate the optimization process using parallel computing.
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Lizy-Destrez, Stéphanie [Verfasser], and Ernst [Akademischer Betreuer] Messerschmid. "Operational scenarios optimization for resupply of crew and cargo of an International gateway Station located near the Earth-Moon-Lagrangian point-2 / Stéphanie Lizy-Destrez ; Betreuer: Ernst Messerschmid." Stuttgart : Universitätsbibliothek der Universität Stuttgart, 2016. http://d-nb.info/111850772X/34.
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Hussein, Ahmed Abd Elmonem Ahmed. "Dynamical System Representation and Analysis of Unsteady Flow and Fluid-Structure Interactions." Diss., Virginia Tech, 2018. http://hdl.handle.net/10919/85626.
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A dynamical system approach is utilized to reduce the representation order of unsteady fluid flows and fluid-structure interaction systems. This approach allows for significant reduction in the computational cost of their numerical simulations, implementation of optimization and control methodologies and assessment of their dynamic stability. In the first chapter, I present a new Lagrangian function to derive the equations of motion of unsteady point vortices. This representation is a reconciliation between Newtonian and Lagrangian mechanics yielding a new approach to model the dynamics of these vortices. In the second chapter, I investigate the flutter of a helicopter rotor blade using finite-state time approximation of the unsteady aerodynamics. The analysis showed a new stability region that could not be determined under the assumption of a quasi-steady flow. In the third chapter, I implement the unsteady vortex lattice method to quantify the effects of tail flexibility on the propulsive efficiency of a fish. I determine that flexibility enhances the propulsion. In the fourth chapter, I consider the stability of a flapping micro air vehicle and use different approaches to design the transition from hovering to forward flight. I determine that first order averaging is not suitable and that time periodic dynamics are required for the controller to achieve this transition. In the fifth chapter, I derive a mathematical model for the free motion of a two-body planar system representing a fish under the action of coupled dynamics and hydrodynamics loads. I conclude that the psicform fish family are inherently stable under certain conditions that depend on the location of the center of mass.<br>Ph. D.<br>We present modeling approaches of the interaction between flying or swimming bodies and the surrounding fluids. We consider their stability as they perform special maneuvers. The approaches are applied to rotating blades of helicopters, fish-like robots, and micro-air vehicles. We develop and validate a new mathematical representation for the flow generated by moving or deforming elements. We also assess the effects of fast variations in the flow on the stability of a rotating helicopter blade. The results point to a new stable regime for their operation. In other words, the fast flow variations could stabilize the rotating blades. These results can also be applied to the analysis of stability of rotating blades of wind turbines. We consider the effects of flexing a tail on the propulsive force of fish-like robots. The results show that adding flexibility enhances the efficiency of the fish propulsion. Inspired by the ability of some birds and insects to transition from hovering to forward motion, we thoroughly investigate different approaches to model and realize this transition. We determine that no simplification should be applied to the rigorous model representing the flapping flight in order to model transition phenomena correctly. Finally, we model the forward-swim dynamics of psciform and determine the condition on the center of mass for which a robotic fish can maintain its stability. This condition could help in designing fish-like robots that perform stable underwater maneuvers.
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FERRACHAT, SYLVAINE. "Melange par convection tridimensionnel et survivance des heterogeneites geochimiques dans le manteau." Université Joseph Fourier (Grenoble), 2000. http://www.theses.fr/2000GRE10148.
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La signature geochimique des basaltes de rides ou de points chauds nous renseigne sur la dynamique du manteau terrestre. Le manteau superficiel, echantillonne dans les basaltes de rides, nous apparait essentiellement homogene. A l'oppose, le manteau profond, echantillonne dans les basaltes de points chauds, se revele tres heterogene. Ceci semble contredire la plupart des observations et contraintes issues de la geophysique : la convection du manteau est tres efficace, et elle genere vraisemblablement des flux de matiere importants entre parties superieure et inferieure. Comment, dans ces conditions, preserver des zones geochimiquement tres differentes ? dans cette these, nous etudions les proprietes de melange d'ecoulements simples simulant la convection du manteau pour tenter de donner un sens a la signature geochimique des basaltes. Nous montrons tout d'abord que la geometrie et la vitesse des plaques lithospheriques sont cruciales pour l'efficacite du melange de l'ecoulement mantellique. Avec des conditions aux limites tridimensionnelles relativement realistes, on peut preserver des zones heterogenes dans un systeme globalement homogene. Ensuite, nous mettons en evidence le fait que la stratification visqueuse du manteau ne peut etre invoquee pour expliquer les differences geochimiques entre parties superficielle et profonde. Nous montrons par contre qu'envisager l'existence d'un reservoir de croute oceanique ancienne dans la couche d peut permettre d'expliquer la signature des basaltes. Enfin, nous presentons une etude comparative des resultats de simulations de convection et de modeles de boites geochimiques concernant la dynamique du manteau. Il apparait que les seconds devraient utiliser environ 15 boites pour que
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Tran, Ngoc Nguyen. "Infeasibility detection and regularization strategies in nonlinear optimization." Thesis, Limoges, 2018. http://www.theses.fr/2018LIMO0059/document.
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Dans cette thèse, nous nous étudions des algorithmes d’optimisation non linéaire. D’une part nous proposons des techniques de détection rapide de la non-réalisabilité d’un problème à résoudre. D’autre part, nous analysons le comportement local des algorithmes pour la résolution de problèmes singuliers. Dans la première partie, nous présentons une modification d’un algorithme de lagrangien augmenté pour l’optimisation avec contraintes d’égalité. La convergence quadratique du nouvel algorithme dans le cas non-réalisable est démontrée théoriquement et numériquement. La seconde partie est dédiée à l’extension du résultat précédent aux problèmes d’optimisation non linéaire généraux avec contraintes d’égalité et d’inégalité. Nous proposons une modification d’un algorithme de pénalisation mixte basé sur un lagrangien augmenté et une barrière logarithmique. Les résultats théoriques de l’analyse de convergence et quelques tests numériques montrent l’avantage du nouvel algorithme dans la détection de la non-réalisabilité. La troisième partie est consacrée à étudier le comportement local d’un algorithme primal-dual de points intérieurs pour l’optimisation sous contraintes de borne. L’analyse locale est effectuée sans l’hypothèse classique des conditions suffisantes d’optimalité de second ordre. Celle-ci est remplacée par une hypothèse plus faible basée sur la notion de borne d’erreur locale. Nous proposons une technique de régularisation de la jacobienne du système d’optimalité à résoudre. Nous démontrons ensuite des propriétés de bornitude de l’inverse de ces matrices régularisées, ce qui nous permet de montrer la convergence superlinéaire de l’algorithme. La dernière partie est consacrée à l’analyse de convergence locale de l’algorithme primal-dual qui est utilisé dans les deux premières parties de la thèse. En pratique, il a été observé que cet algorithme converge rapidement même dans le cas où les contraintes ne vérifient l’hypothèse de qualification de Mangasarian-Fromovitz. Nous démontrons la convergence superlinéaire et quadratique de cet algorithme, sans hypothèse de qualification des contraintes<br>This thesis is devoted to the study of numerical algorithms for nonlinear optimization. On the one hand, we propose new strategies for the rapid infeasibility detection. On the other hand, we analyze the local behavior of primal-dual algorithms for the solution of singular problems. In the first part, we present a modification of an augmented Lagrangian algorithm for equality constrained optimization. The quadratic convergence of the new algorithm in the infeasible case is theoretically and numerically demonstrated. The second part is dedicated to extending the previous result to the solution of general nonlinear optimization problems with equality and inequality constraints. We propose a modification of a mixed logarithmic barrier-augmented Lagrangian algorithm. The theoretical convergence results and the numerical experiments show the advantage of the new algorithm for the infeasibility detection. In the third part, we study the local behavior of a primal-dual interior point algorithm for bound constrained optimization. The local analysis is done without the standard assumption of the second-order sufficient optimality conditions. These conditions are replaced by a weaker assumption based on a local error bound condition. We propose a regularization technique of the Jacobian matrix of the optimality system. We then demonstrate some boundedness properties of the inverse of these regularized matrices, which allow us to prove the superlinear convergence of our algorithm. The last part is devoted to the local convergence analysis of the primal-dual algorithm used in the first two parts of this thesis. In practice, it has been observed that this algorithm converges rapidly even in the case where the constraints do not satisfy the Mangasarian-Fromovitz constraint qualification. We demonstrate the superlinear and quadratic convergence of this algorithm without any assumption of constraint qualification
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Munoz, Jean-Philippe. "Sun-perturbed dynamics of a particle in the vicinity of the Earth-Moon triangular libration points." 2008. http://hdl.handle.net/2152/17944.
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This study focuses on the Sun's influence on the motion near the triangular libration points of the Earth-Moon system. It is known that there exists a very strong resonant perturbation near those points that produces large deviations from the libration points, with an amplitude of about 250,000 km and a period of 1,500 days. However, it has been shown that it is possible to find initial conditions that negate the effects of that perturbation, even resulting in stable, although very large, periodic orbits. Using two different models, the goal of this research is to determine the initial configurations of the Earth-Moon-Sun system that produce minimal deviations from the libration points, and to provide a better understanding of the dynamics of this highly nonlinear problem. First, the Bicircular Problem (BCP) is considered, which is an idealized model of the Earth-Moon-Sun System. The impact of the initial configuration of the Earth-Moon-Sun system is studied for various propagation times and it is found that there exist two initial configurations that produce minimal deviations from L₄ or L₅. The resulting trajectories are very sensitive to the initial configuration, as the mean deviation from the libration points can decrease by 30,000 km with less than a degree change in the initial configuration. Two critical initial configurations of the system were identified that could allow a particle to remain within 30,000 km of the libration points for as long as desired. A more realistic model, based on JPL ephemerides, is also used, and the influence of the initial epoch on the motion near the triangular points is studied. Through the year 2007, 51 epochs are found that produce apparently stable librational motion near L₄, and 60 near L₅. But the motion observed depends greatly on the initial epoch. Some epochs are even found to significantly reduce the deviation from L₄ and L₅, with the spacecraft remaining within at most 90,000 km from the triangular points for upwards of 3,000 days. Similarly to what was observed in the BCP, these trajectories are found to be extremely sensitive to the initial epoch.<br>text
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Paroda, Garcia Zeferino. "A modified augmented Lagrangian merit function, and Q-superlinear characterization results for primal-dual Quasi-Newton interior-point method for nonlinear programming." Thesis, 1997. http://hdl.handle.net/1911/19195.
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Two classes of primal-dual interior-point methods for nonlinear programming are studied. The first class corresponds to a path-following Newton method formulated in terms of the nonnegative variables rather than all primal and dual variables. The centrality condition is a relaxation of the perturbed Karush-Kuhn-Tucker condition and primarily forces feasibility in the constraints. In order to globalize the method using a linesearch strategy, a modified augmented Lagrangian merit function is defined in terms of the centrality condition. The second class is the Quasi-Newton interior-point methods. In this class the well known Boggs-Tolle-Wang characterization of Q-superlinear convergence for Quasi-Newton method for equality constrained optimization is extended. Critical issues in this extension are; the choice of the centering parameter, the choice of the steplength parameter, and the choice of the primary variables.
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Talavatifard, Habiballah. "Application of L1 Minimization Technique to Image Super-Resolution and Surface Reconstruction." Thesis, 2013. http://hdl.handle.net/1969.1/149512.
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A surface reconstruction and image enhancement non-linear finite element technique based on minimization of L1 norm of the total variation of the gradient is introduced. Since minimization in the L1 norm is computationally expensive, we seek to improve the performance of this algorithm in two fronts: first, local L1- minimization, which allows parallel implementation; second, application of the Augmented Lagrangian method to solve the minimization problem. We show that local solution of the minimization problem is feasible. Furthermore, the Augmented Lagrangian method can successfully be used to solve the L1 minimization problem. This result is expected to be useful for improving algorithms computing digital elevation maps for natural and urban terrain, fitting surfaces to point-cloud data, and image super-resolution.
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Prajapat, Ganesh Prasad. "Advanced modeling and control of DFIG based wind turbine systems." Thesis, 2018. http://localhost:8080/xmlui/handle/12345678/7602.
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Schulz, René M. "Microlocal Analysis of Tempered Distributions." Doctoral thesis, 2014. http://hdl.handle.net/11858/00-1735-0000-0022-5F76-E.
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Diese Dissertation ist dem Studium temperierter Distributionen mittels mikrolokaler Methoden gewidmet. Die fundamentale Größe der mikrolokalen Analysis, die Wellenfrontmenge, wird durch zwei analoge Konzepte ersetzt, die den pseudo-differentiellen SG- und Shubin-Kalkülen zugeordnet sind. Die Eigenschaften dieser globalen Wellenfrontmengen werden studiert und ferner werden unterschiedliche Möglichkeiten, diese globalen Singularitäten zu charakterisieren, untersucht, insbesondere mittels der FBI-Transformation.
Zahlreiche Konstruktionen, die den klassischen Wellenfrontmengenbegriff beinhalten, werden in den globalen Kontext übersetzt, insbesondere Rechenoperationen mit temperierten Distributionen wie etwa (getwistete) Produkte, Pull-backs und Paarungen, für die mikrolokale Existenzkriterien angegeben werden.
Als eine Anwendung wird eine Klasse von temperierten Oszillatorintegralen eingeführt, welche durch inhomogene Phasenfunktionen und Amplituden aus SG-Symbolklassen parametrisiert werden. Die SG-Wellenfrontmengen dieser Distributionen werden untersucht und es stellt sich heraus, dass diese durch eine Verallgemeinerung der Menge stationärer Punkte der Phasenfunktionen beschränkt werden.
In diesem Kontext wird eine Verallgemeinerung des klassischen Begriffs einer konischen Lagrange-Untermannifaltigkeit des T*R^d vorgenommen und diese Objekte werden auf ihre Parametrisierungseigenschaften untersucht. Es stellt sich heraus, dass jedes solche Objekt lokal als die Menge der stationären Punkte einer SG-Phasenfunktion realisiert werden kann.
Als weitere Anwendung werden einige Konstruktionen der axiomatischen Quantenfeldtheorie, die Distributionen beinhalten, im temperierten Kontext realisiert.