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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.
291

Méthodes efficaces de capture de front de pareto en conception mécanique multicritère : applications industrielles

Benki, Aalae 28 January 2014 (has links) (PDF)
Dans le domaine d'optimisation de forme de structures, la réduction des coûts et l'amélioration des produits sont des défis permanents à relever. Pour ce faire, le procédé de mise en forme doit être optimisé. Optimiser le procédé revient alors à résoudre un problème d'optimisation. Généralement ce problème est un problème d'optimisation multicritère très coûteux en terme de temps de calcul, où on cherche à minimiser plusieurs fonctions coût en présence d'un certain nombre de contraintes. Pour résoudre ce type de problème, on a développé un algorithme robuste, efficace et fiable. Cet algorithme, consiste à coupler un algorithme de capture de front de Pareto (NBI ou NNCM) avec un métamodèle (RBF), c'est-à-dire des approximations des résultats des simulations coûteuses. D'après l'ensemble des résultats obtenus par cette approche, il est intéressant de souligner que la capture de front de Pareto génère un ensemble des solutions non dominées. Pour savoir lesquelles choisir, le cas échéant, il est nécessaire de faire appel à des algorithmes de sélection, comme par exemple Nash et Kalai-Smorodinsky. Ces deux approches, issues de la théorie des jeux, ont été utilisées pour notre travail. L'ensemble des algorithmes sont validés sur deux cas industriels proposés par notre partenaire industriel. Le premier concerne un modèle 2D du fond de la canette (elasto-plasticité) et le second est un modèle 3D de la traverse (élasticité linéaire). Les résultats obtenus confirment l'efficacité de nos algorithmes développés.
292

Mobility management for the information centric future internet

Saleem, Muhammad Shoaib 19 November 2012 (has links) (PDF)
The contemporary Internet ecosystem today has gone through series of evolutionary changes during the last forty or fifty years. Though it was designed as a network with fixed nodes, it has scaled well enough with the development of new technologies both in fixed and wireless networks. Initially, the communication model of the Internet was based on the telephone network (and can be considered as the 1st Generation Internet). Later, its transition as a client-server model made it a network where communication systems exchange data over dedicated links. This 2nd Generation Internet, over the years, has been challenged by many problems and issues such as network congestion, path failure, DOS attacks, mobility issues for wireless networks, etc. The Internet users always look for some information, irrespectively where it is located or stored. This approach is the basic building block for a network architecture where information is considered as the premier entity. Such networks, in general, are termed as Information Centric Network (ICN), where information takes centric position superseding the node centric approach like in the current Internet. The problems faced by the current Internet architecture, mentioned above, can be handled with a unifying approach by putting the information at the centre of the network architecture. On a global scale, this network architecture design is termed as the Future Information Centric Internet. Similarly, Mobile Internet usage has increased overwhelmingly in the last decade. There has been an estimated 1.2 billion mobile broad-band subscriptions for 2.4 billion Internet users in 2011. Because of the increased spectrum efficiency and ubiquitous availability of cellular connectivity, the seamless mobility and connectivity is now considered as daily life commodity. However, in the case of the Internet, IP based mobility solutions cannot catch up in performance with the fast evolution of cellular networks. Therefore, one of the primary goals for the Future Internet is the design of mobility management schemes that overcome the issues in wireless networks such as handover and location management, multihoming, security, etc. In this thesis, we have proposed a mobility management solution in wireless networks in the context of ICN in general and in the context of Network of Information (NetInf) in particular. NetInf is ICN-based Future Internet architecture. We propose a NetInf Mobile Node (NetInf MN) architecture which is backward compatible with the current Internet architecture as well. This cross architecture design for mobility support works closely with Central Control Unit (CCU) (network entity) for improved performance in case of handover management in wireless networks. The Virtual Node Layer (VNL) algorithm explains how different modules of NetInf MN and CCU units work together. The game theoretical and Reinforcement Learning (CODIPAS-RL) scheme based mathematical model shows how handover management and data relaying in the wireless networks can increase the network coverage through cooperative diversity. Simulation results show that the proposed model achieves both Nash and Stackelberg equilibria where as the selected CODIPAS-RL scheme reaches global optimum. Finally, as a use case example of NetInf architecture, we propose the NetInf Email service that does not require dedicated servers or dedicated port unlike the current email service. The use of asymmetric keys as user's ID is the unique feature proposed for this service. The NetInf email service architecture framework presented, explains how different architectural components work together. We discuss different challenges and requirements related to this service. The prototype developed for the Network of Information will be used for the implementation of this service
293

Unidimensional and Evolution Methods for Optimal Transportation

Bonnotte, Nicolas 16 December 2013 (has links) (PDF)
In dimension one, optimal transportation is rather straightforward. The easiness with which a solution can be obtained in that setting has recently been used to tackle more general situations, each time thanks to the same method. First, disintegrate your problem to go back to the unidimensional case, and apply the available 1D methods to get a first result; then, improve it gradually using some evolution process.This dissertation explores that direction more thoroughly. Looking back at two problems only partially solved this way, I show how this viewpoint in fact allows to go even further.The first of these two problems concerns the computation of Yann Brenier's optimal map. Guillaume Carlier, Alfred Galichon, and Filippo Santambrogio found a new way to obtain it, thanks to an differential equation for which an initial condition is given by the Knothe--Rosenblatt rearrangement. (The latter is precisely defined by a series of unidimensional transformations.) However, they only dealt with discrete target measures; I~generalize their approach to a continuous setting. By differentiation, the Monge--Ampère equation readily gives a PDE satisfied by the Kantorovich potential; but to get a proper initial condition, it is necessary to use the Nash--Moser version of the implicit function theorem.The basics of optimal transport are recalled in the first chapter, and the Nash--Moser theory is exposed in chapter 2. My results are presented in chapter 3, and numerical experiments in chapter 4.The last chapter deals with the IDT algorithm, devised by François Pitié, Anil C. Kokaram, and Rozenn Dahyot. It builds a transport map that seems close enough to the optimal map for most applications. A complete mathematical understanding of the procedure is, however, still lacking. An interpretation as a gradient flow in the space of probability measures is proposed, with the sliced Wasserstein distance as the functional. I also prove the equivalence between the sliced and usual Wasserstein distances.
294

Kontingenzformen : Realisierungsweisen des fiktionalen Erzählens bei Nashe, Sterne und Byron /

Erchinger, Philipp, January 2009 (has links)
Zugl.: Frankfurt am Main, Univ., Diss., 2007.
295

Game-Theoretic Relay Selection and Power Control in Fading Wireless Body Area Networks

2015 December 1900 (has links)
The trend towards personalized ubiquitous computing has led to the advent of a new generation of wireless technologies, namely wireless body area networks (WBANs), which connect the wearable devices into the Internet-of-Things. This thesis considers the problems of relay selection and power control in fading WBANs with energy-efficiency and security considerations. The main body of the thesis is formed by two papers. Ideas from probability theory are used, in the first paper, to construct a performance measure signifying the energy efficiency of transmission, while in the second paper, information-theoretic principles are leveraged to characterize the transmission secrecy at the wireless physical layer (PHY). The hypothesis is that exploiting spatial diversity through multi-hop relaying is an effective strategy in a WBAN to combat fading and enhance communication throughput. In order to analytically explore the problems of optimal relay selection and power control, proper tools from game theory are employed. In particular, non-cooperative game-theoretic frameworks are developed to model and analyze the strategic interactions among sensor nodes in a WBAN when seeking to optimize their transmissions in the uplink. Quality-of-service requirements are also incorporated into the game frameworks, in terms of upper bounds on the end-to-end delay and jitter incurred by multi-hop transmission, by borrowing relevant tools from queuing theory. The proposed game frameworks are proved to admit Nash equilibria, and distributed algorithms are devised that converge to stable Nash solutions. The frameworks are then evaluated using numerical simulations in conditions approximating actual deployment of WBANs. Performance behavior trade-offs are investigated in an IEEE 802.15.6-based ultra wideband WBAN considering various scenarios. The frameworks show remarkable promise in improving the energy efficiency and PHY secrecy of transmission, at the expense of an admissible increase in the end-to-end latency.
296

Essays on household taxation and competition between heterogeneous firms

Oliveira, Érica Diniz January 2014 (has links)
Submitted by Érica Diniz (ericadiniz@gmail.com) on 2015-01-12T19:03:28Z No. of bitstreams: 1 versaodigital_tesedoutorado_EricaDiniz.pdf: 3599824 bytes, checksum: b9f58b1c27e6f83606dfd16d6c2e165d (MD5) / Approved for entry into archive by BRUNA BARROS (bruna.barros@fgv.br) on 2015-01-15T11:48:49Z (GMT) No. of bitstreams: 1 versaodigital_tesedoutorado_EricaDiniz.pdf: 3599824 bytes, checksum: b9f58b1c27e6f83606dfd16d6c2e165d (MD5) / Approved for entry into archive by Marcia Bacha (marcia.bacha@fgv.br) on 2015-02-05T12:01:45Z (GMT) No. of bitstreams: 1 versaodigital_tesedoutorado_EricaDiniz.pdf: 3599824 bytes, checksum: b9f58b1c27e6f83606dfd16d6c2e165d (MD5) / Made available in DSpace on 2015-02-05T12:02:06Z (GMT). No. of bitstreams: 1 versaodigital_tesedoutorado_EricaDiniz.pdf: 3599824 bytes, checksum: b9f58b1c27e6f83606dfd16d6c2e165d (MD5) Previous issue date: 2013-10-28 / Essa tese é constituída por três artigos: 'Tax Filing Choices for the Household', 'Optimal Tax for the Household: Collective and Unitary Approaches' e 'Vertical Differentiation and Heterogeneous Firms'.
297

Avaliação dos efeitos de terapias com células de medula óssea em modelo experimental de diabetes mellitus tipo 2 / Avaliação dos efeitos de terapias com células de medula óssea em modelo experimental dediabetes mellitus tipo 2

Souza, Siane Campos de January 2010 (has links)
Submitted by Ana Maria Fiscina Sampaio (fiscina@bahia.fiocruz.br) on 2012-08-29T20:39:47Z No. of bitstreams: 1 Siane Campos. Avaliação dos efeitos de terapias com celulas de medula óssea modelo experimental de diabetes mellitus tipo 2.pdf: 7027812 bytes, checksum: 4b12aa1315741fb327aacac8f55889a7 (MD5) / Made available in DSpace on 2012-08-29T20:39:47Z (GMT). No. of bitstreams: 1 Siane Campos. Avaliação dos efeitos de terapias com celulas de medula óssea modelo experimental de diabetes mellitus tipo 2.pdf: 7027812 bytes, checksum: 4b12aa1315741fb327aacac8f55889a7 (MD5) Previous issue date: 2010 / Fundação Oswaldo Cruz. Centro de Pesquisas Gonçalo Moniz. Salvador, Bahia, Brasil / O diabetes mellitus tipo 2 (DM2) é uma disfunção metabólica que afeta milhões de pessoas em números crescentes em todo o mundo. É caracterizado pela resistência dos tecidosalvo à insulina e/ou defeitos na sua secreção, acarretando uma hiperglicemia crônica, que pode gerar danos no sistema cardiovascular, nervoso, olhos, rins e fígado e representam um ônus para os sistemas de saúde. Doença de etiologia múltipla, o DM2 resulta da interação entre predisposição genética e fatores ambientais, destacando-se a obesidade. O tratamento do DM2 geralmente envolve mudanças de hábito e drogas anti-hiperglicemiantes ou hipoglicemiantes que podem acarretar efeitos colaterais. As recentes descobertas sobre a plasticidade e o potencial terapêutico das células-tronco de medula óssea indicam uma possível aplicação destas no tratamento do DM2 e suas complicações. Para investigar esse potencial, foi estabelecido um modelo de diabetes em camundongos C57Bl/6 através da administração de dieta hipergordurosa. Após o período de indução, os animais apresentavam obesidade, hiperglicemia, intolerância à glicose, proteinúria e esteato-hepatite não-alcoólica. Camundongos C57Bl/6 fêmeas não desenvolvem obesidade, hiperglicemia e DM2 quando submetidas à mesma dieta que os machos. Apenas os machos foram então tratados com células mononucleares de medula óssea e acompanhados durante seis meses. A terapia com células mononucleares de medula óssea não reduz o peso corpóreo dos animais obesos e diabéticos. Três e seis meses após a terapia, não foi observada redução da glicemia de jejum dos animais.Três meses após a terapia, observou-se redução da intolerância a glicose nos animais alimentados com dieta high-fat.Houve uma redução da fibrose perissinusoidal no fígado após 3 meses de terapia e esta diferença se manteve até 6 meses após a terapia. / Type 2 diabetes mellitus (T2DM) is a metabolic disorder that affects millions of people and grows worldwide. It is characterized by insulin resistance in peripheral tissues and/or impaired insulin secretion, leading to chronic hyperglycemia associated with long-term consequences that include damage and dysfunction of the cardiovascular system, eyes, kidneys and nerves. T2DM is a multifactorial disease determined by genetic and environmental factors, especially obesity. The usual treatment involves antihyperglycemic and hypoglycemic drugs that can provoke undesirable side effects. Recent findings on hematopoietic stem cell plasticity and therapeutic potential suggest their use as an alternative treatment for T2DM and its consequences. In order to investigate this potential, a model of diabetes was induced in C57Bl/6 mice through administration of a high-fat diet. Animals developed obesity, hyperglycemia, glucose intolerance, proteinuria and nonalcoholic steato-hepatitis. Female C57Bl/6 mice do not developed obesity, hyperglycemia and T2DM when submitted the male’s diet. After the induction period, only the male mice were treated with bone marrow mononuclear cells and observed during 6 months. Cell mononuclear from bone marrow therapy do not reduced body weight from obesity and diabetes animals. Three and six months after the therapy, we do not observed reduction from glycemia. Three months after the therapy, observed reduction glucose intolerance in mice high-fat fed. Reduction in fibrosis perisinusoidal liver after thee months from therapy and this difference still until six months after therapy.
298

Controle hierárquico para a equação do calor via estratégia Stackelberg-Nash

Albuquerque., Islanita Cecília Alcantara de 29 September 2011 (has links)
Made available in DSpace on 2015-05-15T11:46:05Z (GMT). No. of bitstreams: 1 arquivototal.pdf: 674722 bytes, checksum: eb17d5816a0fce98d1def5be593711f1 (MD5) Previous issue date: 2011-09-29 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / We have as main issue in this work the Hierarchical Control, which consists in a leader-followers system. We studied in special the heat equation approximate controllability under Stackelberg-Nash’s strategy, which is directed in controlling every system from local controls choices with the minimum possible costs. / Temos como principal tema neste trabalho o Controle Hierárquico, que consiste em um sistema de líder e seguidores. Estudamos em especial a controlabilidade aproximada da equação do Calor sob a estratégia de Stackelberg-Nash, estratégia esta direcionada em controlar todo sistema a partir de escolhas de controles locais com o mínimo de custos possíveis.
299

Řešení koncovek ve velkých hrách s neúplnou informací jako je např. Poker / Solving Endgames in Large Imperfect-Information Games such as Poker

Ha, Karel January 2016 (has links)
Title: Solving Endgames in Large Imperfect-Information Games such as Poker Author: Bc. Karel Ha Department: Department of Applied Mathematics Supervisor: doc. Mgr. Milan Hladík, Ph.D., Department of Applied Mathematics Abstract: Endgames have a distinctive role for players. At the late stage of games, many aspects are finally clearly defined, deeming exhaustive analysis tractable. Specialised endgame handling is rewarding for games with perfect information (e.g., Chess databases pre-computed for entire classes of endings, or dividing Go board into separate independent subgames). An appealing idea would be to extend this approach to imperfect-information games such as the famous Poker: play the early parts of the game, and once the subgame becomes feasible, calculate an ending solution. However, the problem is much more complex for imperfect information. Subgames need to be generalized to account for information sets. Unfortunately, such a generalization cannot be solved straightaway, as it does not generally preserve optimality. As a consequence, we may end up with a far more exploitable strategy. There are currently three techniques to deal with this challenge: (a) disregard the problem entirely; (b) use a decomposition technique, which sadly retains only the same quality; (c) or formalize improvements of...
300

Distributed Algorithms for Power Allocation Games on Gaussian Interference Channels

Krishnachaitanya, A January 2016 (has links) (PDF)
We consider a wireless communication system in which there are N transmitter-receiver pairs and each transmitter wants to communicate with its corresponding receiver. This is modelled as an interference channel. We propose power allocation algorithms for increasing the sum rate of two and three user interference channels. The channels experience fast fading and there is an average power constraint on each transmitter. In this case receivers use successive decoding under strong interference, instead of treating interference as noise all the time. Next, we u se game theoretic approach for power allocation where each receiver treats interference as noise. Each transmitter-receiver pair aims to maximize its long-term average transmission rate subject to an average power constraint. We formulate a stochastic game for this system in three different scenarios. First, we assume that each user knows all direct and crosslink channel gains. Next, we assume that each user knows channel gains of only the links that are incident on its receiver. Finally, we assume that each use r knows only its own direct link channel gain. In all cases, we formulate the problem of finding the Nash equilibrium(NE) as a variational in equality problem. For the game with complete channel knowledge, we present an algorithm to solve the VI and we provide weaker sufficient conditions for uniqueness of the NE than the sufficient conditions available in the literature. Later, we present a novel heuristic for solving the VI under general channel conditions. We also provide a distributed algorithm to compute Pare to optimal solutions for the proposed games. We use Bayesian learning that guarantees convergence to an Ɛ-Nash equilibrium for the incomplete information game with direct link channel gain knowledge only, that does not require knowledge of the power policies of other users but requires feedback of the interference power values from a receiver to its corresponding transmitter. Later, we consider a more practical scenario in which each transmitter transmits data at a certain rate using a power that depends on the channel gain to its receiver. If a receiver can successfully receive the message, it sends an acknowledgement(ACK), else it sends a negative ACK(NACK). Each user aims to maximize its probability of successful transmission. We formulate this problem as a stochastic game and propose a fully distributed learning algorithm to find a correlated equilibrium(CE). In addition, we use a no regret algorithm to find a coarse correlated equilibrium(CCE) for our power allocation game. We also propose a fully distributed learning algorithm to find a Pareto optimal solution. In general Pareto points do not guarantee fairness among the users. Therefore we also propose an algorithm to compute a Nash bargaining solution which is Pareto optimal and provides fairness among the users. Finally, we extend these results when each transmitter sends data at multiple rates rather than at a fixed rate.

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