Dissertations / Theses on the topic 'LMS ALGORITHMS'
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Johansson, Sven. "Active Control of Propeller-Induced Noise in Aircraft : Algorithms & Methods." Doctoral thesis, Karlskrona, Ronneby : Blekinge Institute of Technology, 2000. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-00171.
Full textBuller i vår dagliga miljö kan ha en negativ inverkan på vår hälsa. I många sammanhang, i tex bilar, båtar och flygplan, förekommer lågfrekvent buller. Lågfrekvent buller är oftast inte skadligt för hörseln, men kan vara tröttande och försvåra konversationen mellan personer som vistas i en utsatt miljö. En dämpning av bullernivån medför en förbättrad taluppfattbarhet samt en komfortökning. Att dämpa lågfrekvent buller med traditionella passiva metoder, tex absorbenter och reflektorer, är oftast ineffektivt. Det krävs stora, skrymmande absorbenter för att dämpa denna typ av buller samt tunga skiljeväggar för att förhindra att bullret transmitteras vidare från ett utrymme till ett annat. Metoder som är mera lämpade vid dämpning av lågfrekvent buller är de aktiva. De aktiva metoderna baseras på att en vågrörelse som ligger i motfas med en annan överlagras och de släcker ut varandra. Bullerdämpningen erhålls genom att ett ljudfält genereras som är lika starkt som bullret men i motfas med detta. De aktiva bullerdämpningsmetoderna medför en effektiv dämpning av lågfrekvent buller samtidigt som volymen, tex hos bilkupen eller båt/flygplanskabinen ej påverkas nämnvärt. Dessutom kan fordonets/farkostens vikt reduceras vilket är tacksamt för bränsleförbrukningen. I de flesta tillämpningar varierar bullrets karaktär, dvs styrka och frekvensinnehåll. För att följa dessa variationer krävs ett adaptivt (självinställande) reglersystem som styr genereringen av motljudet. I propellerflygplan är de dominerande frekvenserna i kabinbullret relaterat till propellrarnas varvtal, man känner alltså till frekvenserna som skall dämpas. Man utnyttjar en varvtalssignal för att generera signaler, så kallade referenssignaler, med de frekvenser som skall dämpas. Dessa bearbetas av ett reglersystem som generar signaler till högtalarna som i sin tur generar motljudet. För att ställa in högtalarsignalerna så att en effektiv dämpning erhålls, används mikrofoner utplacerade i kabinen som mäter bullret. För att åstadkomma en effektiv bullerdämpning i ett rum, tex i en flygplanskabin, behövs flera högtalare och mikrofoner, vilket kräver ett avancerat reglersystem. I doktorsavhandlingen ''Active Control of Propeller-Induced Noise in Aircraft'' behandlas olika metoder för att reducera kabinbuller härrörande från propellrarna. Här presenteras olika strukturer på reglersystem samt beräkningsalgoritmer för att ställa in systemet. För stora system där många högtalare och mikrofoner används, samt flera frekvenser skall dämpas, är det viktigt att systemet inte behöver för stor beräkningskapacitet för att generera motljudet. Metoderna som behandlas ger en effektiv dämpning till låg beräkningskostnad. Delar av materialet som presenteras i avhandlingen har ingått i ett EU-projekt med inriktning mot bullerundertryckning i propellerflygplan. I projektet har flera europeiska flygplanstillverkare deltagit. Avhandlingen behandlar även aktiv bullerdämpning i headset, som används av helikopterpiloter. I denna tillämpning har aktiv bullerdämpning används för att öka taluppfattbarheten.
Callahan, Michael J. "Estimating Channel Identification Quality in Passive Radar Using LMS Algorithms." Wright State University / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=wright1503508289044109.
Full textDabeer, Onkar. "Convergence analysis of the LMS and the constant modulus algorithms /." Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2002. http://wwwlib.umi.com/cr/ucsd/fullcit?p3055781.
Full textDuan, Jie. "Active Control of Vehicle Powertrain Noise Applying Frequency Domain Filtered-x LMS Algorithm." University of Cincinnati / OhioLINK, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1243614246.
Full textSigrist, Zoé. "Contribution à l'identification de systèmes non-linéaires en milieu bruité pour la modélisation de structures mécaniques soumises à des excitations vibratoires." Thesis, Bordeaux 1, 2012. http://www.theses.fr/2012BOR14655/document.
Full textThis PhD deals with the caracterisation of mechanical structures, by its structural parameters, when only noisy observations disturbed by additive measurement noises, assumed to be zero-mean white and Gaussian, are available. For this purpose, we suggest using discrete-time models with distinct linear and nonlinear parts. The first one allows the structural parameters to be retrieved whereas the second one gives information on the nonlinearity. When dealing with non-recursive Volterra series, we propose an errors-in-variables (EIV) method to jointly estimate the noise variances and the Volterra kernels. We also suggest a modified unbiased LMS algorithm to estimate the model parameters provided that the input-noise variance is known. When dealing with recursive polynomial model, we propose two methods using evolutionary algorithms. The first includes a stop protocol that takes into account the output-noise variance. In the second one, the fitness functions are based on correlation criteria in which the noise influence is removed or compensated
Ting, L. K. "Algorithms and FPGA implementation of adaptive LMS-based predictors for radar pulse identification." Thesis, Queen's University Belfast, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.395207.
Full textNguyen, Ngoc Hung, Majid Dowlatnia, and Azhar Sarfraz. "Implementation of the LMS and NLMS algorithms for Acoustic Echo Cancellationin teleconference systemusing MATLAB." Thesis, Växjö University, School of Mathematics and Systems Engineering, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:vxu:diva-6368.
Full textIn hands-free telephony and in teleconference systems, the main aim is to provide agood free voice quality when two or more people communicate from different places.The problem often arises during the conversation is the creation of acoustic echo. Thisproblem will cause the bad quality of voice signal and thus talkers could not hearclearly the content of the conversation, even thought lost the important information.This acoustic echo is actually the noise which is created by the reflection of soundwaves by the wall of the room and the other things exist in the room. The mainobjective for engineers is the cancellation of this acoustic echo and provides an echofree environment for speakers during conversation. For this purpose, scientists designdifferent adaptive filter algorithms. Our thesis is also to study and simulate theacoustics echo cancellation by using different adaptive algorithms.
Lo, Ming Jengis. "Performance investigation of adaptive filter algorithms and their implementation for MIMO systems." Thesis, University of Canterbury. Electrical and Computer Engineering, 2005. http://hdl.handle.net/10092/1136.
Full textCastelo, Branco César Augusto Santana. "Algoritmos adaptativos LMS normalizados proporcionais: proposta de novos algoritmos para identificação de plantas esparsas." Universidade Federal do Maranhão, 2016. http://tedebc.ufma.br:8080/jspui/handle/tede/1688.
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPQ)
This work proposes new methodologies to optimize the choice of the parameters of the proportionate normalized least-mean-square (PNLMS) adaptive algorithms. The proposed approaches use procedures based on two optimization methods, namely, the golden section and tabu search methods. Such procedures are applied to determine the optimal parameters in each iteration of the adaptation process of the PNLMS and improved PNLMS (IPNLMS) algorithms. The objective function for the proposed procedures is based on the a posteriori estimation error. Performance studies carried out to evaluate the impact of the PNLMS and IPNLMS parameters in the behavior of these algorithms shows that, with the aid of optimization techniques to choose properly such parameters, the performance of these algorithms may be improved in terms of convergence speed for the identification of plants with high sparseness degree. The main goal of the proposed methodologies is to improve the distribution of the adaptation energy between the coefficients of the PNLMS and IPNLMS algorithms, using parameter values that lead to the minimal estimation error of each iteration of the adaptation process. Numerical tests performed (considering various scenarios in which the plant impulse response is sparse) show that the proposed methodologies achieve convergence speeds faster than the PNLMS and IPNLMS algorithms, and other algorithms of the PNLMS class, such as the sparseness controlled IPNLMS (SC-IPNLMS) algorithm.
Neste trabalho, novas metodologias para otimizar a escolha dos parâmetros dos algoritmos adaptativos LMS normalizados proporcionais (PNLMS) são propostas. As abordagens propostas usam procedimentos baseados em dois métodos de otimização, a saber, os métodos da razão áurea e da busca tabu. Tais procedimentos são empregados para determinar os parâmetros ótimos em cada iteração do processo de adaptação dos algoritmos PNLMS e PNLMS melhorado (IPNLMS). A função objetivo adotada pelos procedimentos propostos é baseada no erro de estimação a posteriori. O estudo de desempenho realizado para avaliar o impacto dos parâmetros dos algoritmos PNLMS e IPNLMS no comportamento dos mesmos mostram que, com o auxílio de técnicas de otimização para escolher adequadamente tais parâmetros, o desempenho destes algoritmos pode ser melhorado, em termos de velocidade de convergência, para a identificação de plantas com elevado grau de esparsidade. O principal objetivo das metodologias propostas é melhorar a distribuição da energia de ativação entre os coeficientes dos algoritmos PNLMS e IPNLMS, usando valores de parâmetros que levam ao erro de estimação mínimo em cada iteração do processo de adaptação. Testes numéricos realizados (considerando diversos cenários nos quais a resposta impulsiva da planta é esparsa) mostram que as metodologias propostas alcançam velocidades de convergência superiores às dos algoritmos PNLMS e IPNLMS, além de outros algoritmos da classe PNLMS, tais como o algoritmo IPNLMS com controle de esparsidade (SCIPNLMS).
Hua, Fei. "Adaptation et apprentissage sur des réseaux et des graphiques multitâches." Thesis, Université Côte d'Azur, 2020. http://www.theses.fr/2020COAZ4037.
Full textMultitask learning has received considerable attention in signal processing and machine learning communities. It aims at simultaneously learning several related tasks other than the traditional single-task problems. There also have witnessed a wide spectrum of data processing problems that are network- or graph-structured and require adaptation ability to streaming data and time-varying dynamics. Distributed adaptive learning strategies over networks enable a collection of interconnected agents to accomplish a certain task, such as parameter estimation, collaboratively through local computation and cooperation among neighboring agents. Further, they endow the agents with continuous adaptation and learning ability to track possible drifts in the underlying model. Despite the heterogeneous nature and the fact that each agent may solve a different task in multitask network, it could still benefit from a collaboration between agents to improve the estimation accuracy by leveraging the relations and capitalizing on inductive transfer between them. The objective of this thesis is to devise and analyze multitask adaptive learning strategies over networks and graphs. First, we consider multitask estimation problems where each agent is interested in estimating its own parameter vector and where the parameter vectors at neighboring agents are related linearly according to a set of constraints. Based on the penalty method, an unconstrained optimization problem is reformulated and a distributed algorithm is derived. The behavior of the algorithm in the mean and in the mean-square-error sense is analyzed. Next, we relax the local constraints assumption and consider the multitask problem with non-local constraints. We devise the distributed algorithm by employing a multi-hop relay protocol across the agents. We prove that the algorithm will continue to converge and provide theoretical performance analysis. In the third part, we extend the distributed learning strategies to the emerging graph signal processing applications where the signal itself is network-structured. Several graph diffusion LMS strategies are proposed to cope with streaming graph signals. We also extend the multitask model to graph filters and propose an on-line clustering mechanism. Last, we consider the problem of modeling graph signals by using a combination of multiple graph filters. An efficient algorithm is proposed to simultaneously learn coefficients of multiple graph filters and perform model selection. Simulation and numerical results are provided to illustrate the effectiveness of all proposed algorithms and validate the theoretical analyses
Deyneka, Alexander. "Metody ekvalizace v digitálních komunikačních systémech." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2011. http://www.nusl.cz/ntk/nusl-218963.
Full textSobral, Sónia Rolland. "B-Learning em disciplinas introdutórias de programação." Doctoral thesis, https://repositorium.sdum.uminho.pt/bitstream/1822/9054/1/CapitulosFinal030408vf.pdf, 2008. https://repositorium.sdum.uminho.pt/bitstream/1822/9054/1/CapitulosFinal030408vf.pdf.
Full textAs Tecnologias de Informação e Comunicação já são parte integrante da vida dos cidadãos e dos lares portugueses. A nova era da sociedade do conhecimento conjuga-se na escola com as mudanças do aluno e do seu perfil e o processo de Bolonha. O ensino a distância mediado pela Web e a sua generalização, em particular a aprendizagem mista, b-learning, pelas suas características intrínsecas como o auto-estudo a qualquer hora e em qualquer lugar, o seu carácter motivador, o crescente número de plataformas de suporte, como o MOODLE, e as expectativas de uma aprendizagem colaborativa construtivista, são uma realidade que as nstituições de Ensino Superior têm que tomar em conta. O ensino introdutório de programação nos primeiros anos das Licenciaturas da área da nformática tem uma elevada taxa de reprovações. É um insucesso muitas vezes causador de abandono escolar ou de desmotivação. Porém, pelo seu aspecto propedêutico é uma matéria curricular chave determinante na formação dos alunos e onde o seu desempenho influirá decisivamente no êxito do resto dos estudos da Licenciatura. O b-learning num ambiente construtivista “à Bolonha” aparece como uma possibilidade de solução para este grave problema de insucesso. A questão fundamental que se põe, particularmente com Bolonha é: esta possibilidade de solução resulta? Diminui o insucesso? Para responder a esta questão realizou-se esta nvestigação que usou a plataforma MOODLE, decorreu em dois anos lectivos sucessivos e teve como base a unidade curricular semestral de Algoritmia comum ao primeiro ano das Licenciaturas em Informática ministradas na Universidade Portucalense. No primeiro ano de nvestigação o uso do MOODLE estava acessível aos vinte e quatro alunos de uma das turmas práticas, sendo de noventa e dois o total de alunos inscritos. No segundo ano permitiu-se a nscrição na e-unidade curricular a todos os noventa e três alunos inscritos, tendo sido usada por setenta e cinco deles, e já se realizou no paradigma de Bolonha com a consequente mudança traduzida na nova aproximação ao ensino centrado no aluno e no desenvolvimento das suas competências. Retiraram-se várias lições para alunos, docentes e instituições e concluiu-se que a utilização da aprendizagem mista foi muito eficaz quer objectivamente em relação ao nsucesso quer subjectivamente em relação ao nível de satisfação por parte dos alunos envolvidos.Information and Communication Technologies (ICT) are part of everyday life. Computers and Internet connections have already one place at the Portuguese homes. A new knowledge society era combines with the changes in the school of the student and his profile in the Bologna process. The teaching at distance mediated by the Web, in particular b-learning, by its inherent characteristics such as self-study, use of information technology, anytime, anywhere, its induced motivation, a strong interaction with the teacher and the expectations of a collaborative learning, is by now a reality that institutions of higher education have to consider to choose the best way to improve and enhance the teaching-learning process. The disciplines of “introduction to programming” from the first years in Computer Science degrees have a traditional high rate of failure. This is often a future cause of abandonment and lack of motivation. Its appearance in the beginning makes them key curriculum units, which are crucial in the student’s formation. The student performance decisively influences the success of the reminder of their studies of graduation. B-learning in a constructive environment "for Bologna" emerges as a possible solution to this problem. The key question, particularly with Bologna is: this window of opportunity arises? Reduces the failure? To answer that question this research uses the platform MOODLE and is based on the semester discipline or curriculum unit, in the first year, Algoritmia, common to the courses in Computer Science taught at Universidade Portucalense. In the first year of research MOODLE was available to twenty four students in one class out of ninety two students enrolled in the discipline. In the second year studied, all ninety three students enrolled were allowed to use MOODLE and seventy five students did it. This discipline was already included in the Bologna paradigm, with the new approach to education centered on the student and the development of his skills. With many lessons for students, faculty and institutions and it is concluded that the use of an e-discipline has been very successful, either objectively measured by the rates of approval obtained or subjectively by the level of satisfaction of the students involved.
Orientação: Prof.º Doutor Pedro Cravo Pimenta
Kostrygin, Anatolii. "Precise Analysis of Epidemic Algorithms." Thesis, Université Paris-Saclay (ComUE), 2017. http://www.theses.fr/2017SACLX042/document.
Full textEpidemic algorithms are distributed algorithms in which the agents in thenetwork involve peers similarly to the spread of epidemics. In this work, we focus on randomized rumor spreading -- a class of epidemic algorithms based on the paradigm that nodes call random neighbors and exchange information with these contacts. Randomized rumor spreading has found numerous applications from the consistency maintenance of replicated databases to newsspreading in social networks. Numerous mathematical analyses of different rumor spreading algorithms can be found in the literature. Some of them provide extremely sharp estimates for the performance of such processes, but most of them are based on the inherent properties of concrete algorithms.We develop new simple and generic method to analyze randomized rumor spreading processes in fully connected networks. In contrast to all previous works, which heavily exploit the precise definition of the process under investigation, we only need to understand the probability and the covariance of the events that uninformed nodes become informed. This universality allows us to easily analyze the classic push, pull, and push-pull protocols both in their pure version and in several variations such as when messages fail with constant probability or when nodes call a random number of others each round. Some dynamic models can be analyzed as well, e.g., when the network is a random graph sampled independently each round [Clementi et al. (ESA 2013)]. Despite this generality, our method determines the expected rumor spreading time precisely apart from additive constants, which is more precise than almost all previous works. We also prove tail bounds showing that a deviation from the expectation by more than an additive number of r rounds occurs with probability at most exp(−Ω(r)).We further use our method to discuss the common assumption that nodes can answer any number of incoming calls. We observe that the restriction that only one call can be answered leads to a significant increase of the runtime of the push-pull protocol. In particular, the double logarithmic end phase of the process now takes logarithmic time. This also increases the message complexity from the asymptotically optimal Θ(n log log n) [Karp, Shenker, Schindelhauer, Vöcking (FOCS 2000)] to Θ(n log n). We propose a simple variation of the push-pull protocol that reverts back to the double logarithmic end phase and thus to the Θ(n log log n) message complexity
Silva, Wilander Testone Pereira da. "Modelagem Estocástica: Teoria, Formulação e Aplicações do Algoritmo LMS." Universidade Federal do Maranhão, 2016. http://tedebc.ufma.br:8080/jspui/handle/tede/301.
Full textCoordenação de Aperfeiçoamento de Pessoal de Nível Superior
In this dissertation we present a research in aspects of stochastic modeling, convergence and applications of least mean square (LMS) algorithm, normalized least mean square (NLMS) algorithm and proportionate normalized least mean square (PNLMS) algorithm. Specifically, the aim is to address the LMS algorithm in your extension, defining his concepts, demonstrations of properties, algorithms and analysis of convergence, Learning Curve and Misadjustment of the algorithm in question. Within of the context of sensor networks and spatial filtering is evaluated the performance of the algorithms by the learning curve of the referred algorithms for arrangements of adaptive antennas. In the intrinsic context of the application in electrical engineering, in area of telecommunications that seek the best alternative and aims to optimize the process of transmission/reception to eliminate interference, and the least amount of elements in adaptive antenna arrays, which they are known as smart antenna, which aims to reach a signal noise ratio for small value, with appropriate number of elements. The performance of the LMS algorithm is evaluated in sensor networks that is characterized by an antenna array. Results of computer simulations for different scenarios of operation show that the algorithms have good numerical results of convergence to a suitable choice of the parameters related with the rate of learning that are associated with their average curves and the beamforming of the smart antenna array.
Nesta dissertação de mestrado apresenta-se uma investigação em aspectos de modelagem estocástica, convergência e aplicações dos algoritmos de mínimos quadrados médio (LMS), mínimos quadrados médio normalizado (NLMS) e mínimos quadrados médio normalizado proporcional (PNLMS). Particularmente, aborda-se o Algoritmo LMS em sua extensão, definindo conceitos, demonstrações de propriedades, algoritmos e análise de convergência, Curva de Aprendizagem e Desajuste do referido algoritmo. Dentro do contexto de redes de sensores e filtragem espacial avalia-se o desempenho dos algoritmos por meio da curva de aprendizagem dos referidos algoritmos para os arranjos de antenas adaptativas. No contexto intrínseco da aplicação em engenharia elétrica, isto é, na área de telecomunicações procura-se a melhor alternativa e almeja-se a otimização do processo de transmissão/recepção para eliminar interferências e a menor quantidade de elementos em arranjos de antenas adaptativas, que são conhecidas como antenas inteligentes, e que tem como objetivo atingir uma relação Sinal Ruído para valor pequeno, com número adequado de elementos. O desempenho do algoritmo LMS é avaliado em redes de sensores que é caracterizada por um arranjo de antenas. Resultados de simulações computacionais para diferentes cenários de operação mostram que os algoritmos apresentam bons resultados numéricos de convergência para uma escolha adequada dos parâmetros relacionados com a taxa de aprendizagem que são associadas com suas curvas médias e com a conformação de feixes do arranjo em antenas inteligentes.
Renaud, Yoan. "Quelques aspects algorithmiques sur les systèmes de fermeture." Phd thesis, Université Blaise Pascal - Clermont-Ferrand II, 2008. http://tel.archives-ouvertes.fr/tel-00731341.
Full textCavalcanti, Bruno Jácome. "Análise de modelos de predição de perdas de propagação em redes de comunicações LTE e LTE-Advanced usando técnicas de inteligência artificial." PROGRAMA DE PÓS-GRADUAÇÃO EM ENGENHARIA ELÉTRICA E DE COMPUTAÇÃO, 2017. https://repositorio.ufrn.br/jspui/handle/123456789/25061.
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A perfeita funcionalidade dos sistemas de comunicações de 3ª. e 4ª. gerações requerem, entre outras coisas, do conhecimento dos valores numéricos da predição das perdas de propagação dos sinais propagantes nos ambientes urbano, suburbano e rural. Portanto, o estudo das condições de propagação em um ambiente qualquer sempre será uma preocupação dos engenheiros projetistas. A análise e desenvolvimento de modelos robustos de predição de perdas de propagação em redes de comunicações Long Term Evolution (LTE) e Long Term Evolution Advanced (LTE-A) usando técnicas de Inteligência Artificial são realizadas neste trabalho. Os procedimentos metodológicos empregados foram aplicados no melhoramento da predição dos modelos de perda de propagação empíricos SUI, ECC-33, Ericsson 9999, TR 36.942 e o modelo do Espaço Livre, aplicados em redes LTE e LTE-A nas frequências de 800 MHz, 1800 MHz e 2600 MHz, para ambientes suburbanos em cidades de porte médio do nordeste do Brasil. Assim, nesta tese propõem-se dois modelos de Redes Neurais Artificiais (RNA): (i) o modelo de rede neural com entradas baseadas em erro (RNBE), utilizando como principal alimentador da rede o erro entre dados medidos e simulados, e, (ii) o modelo de rede neural com entradas baseadas no terreno (RNBT). O desempenho desses modelos foram comparados com os modelos de propagação considerados no trabalho e também as versões otimizadas utilizando Algoritmos Genéticos (AG) e o Método dos Mínimos Quadrados (LMS). Também foram realizadas comparações com valores medidos, obtidos a partir de uma campanha de medição realizada na cidade de Natal, Estado do Rio Grande do Norte. Os resultados finais obtidos através de simulações e medições apresentaram boas concordâncias métricas, com destaque para a performance do modelo RNBE. A principal contribuição dessa tese é que, ao utilizar essas técnicas que fazem uso de maneira mais eficiente dos modelos de propagação empíricos, pode-se estimar sinais propagantes realistas, evitando erros no planejamento e implementações de redes sem fio LTE e LTE-A em áreas suburbanas.
The perfect functionality of the 3rd and 4th generation of wireless systems requires, among other parameters, knowledge of the numerical values of the prediction of loss of propagation of propagation signals in urban, suburban and rural environments. Therefore, the study of propagation conditions in any environment will always be a concern of design engineers. The analysis and development of robust propagation loss prediction models in Long Term Evolution (LTE) and Long Term Evolution Advanced (LTE-A) communications networks using Artificial Intelligence techniques is performed in this work. The methodologies used were applied to improve the prediction of loss of empirical propagation SUI, ECC-33, Ericsson 9999, TR 36.942 models and the Free Space model applied in LTE and LTE-A networks in the frequencies of 800 MHz, 1800 MHz and 2600 MHz, for suburban environments in mid-sized cities in northeastern Brazil. Thus, in these thesis two models of Artificial Neural Networks (RNA) are proposed: (i) the neural network model with inputs based on error (RNBE) using as main feeder of the network the error between measured and simulated data, and (ii) the neural network model with land-based inputs (RNBT). The performance of these models was compared with the models of propagation considered in the work and also the versions optimized using Genetic Algorithms (AG) and the Least Square Method (LMS). Comparisons were also made with measured values, obtained from a measurement campaign carried out in the city of Natal, state of Rio Grande do Norte. The final results obtained through simulations and measurements presented good metric concordances, with emphasis on the performance of the RNBE model. Thus, the main contribution of this thesis is that, by using these techniques that make more efficient use of empirical propagation models, we can estimate realistic propagation signals, avoiding errors in the planning and implementations of LTE and LTE- A wireless networks in suburban areas.
Couturier, Jean-François. "Algorithmes exacts et exponentiels sur les graphes : énumération, comptage et optimisation." Thesis, Université de Lorraine, 2012. http://www.theses.fr/2012LORR0325/document.
Full textThe assumption that many problems do not admit algorithm (exact and deterministic) polynomial ate of the advent of the theory of NP-completeness in the 70s. Since many theories and algorithmic techniques have been developed to solve these problems difficult as efficiently as possible. In this thesis, we focus on exact algorithms weakly exponential. The objective is to obtain algorithms complexity 0 * (c ^ n) where n is the size of the data and one constant c as small as possible
Šmíd, Karel. "Adaptivní filtrace biologických signálů." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2008. http://www.nusl.cz/ntk/nusl-217457.
Full textCochet-Terrasson, Jean. "Algorithmes d'itération sur les politiques pour les applications monotones contractantes." Paris, ENMP, 2001. http://www.theses.fr/2001ENMP1012.
Full textCreusefond, Jean. "Caractériser et détecter les communautés dans les réseaux sociaux." Thesis, Normandie, 2017. http://www.theses.fr/2017NORMC203/document.
Full textN this thesis, I first present a new way of characterising communities from a network of timestamped messages. I show that its structure is linked with communities : communication structures are over-represented inside communities while diffusion structures appear mainly on the boundaries.Then, I propose to evaluate communities with a new quality function, compacity, that measures the propagation speed of communications in communities. I also present the Lex-Clustering, a new community detection algorithm based on the LexDFS graph traversal that features some characteristics of information diffusion.Finally, I present a methodology that I used to link quality functions and ground-truths. I introduce the concept of contexts, sets of ground-truths that are similar in some way. I implemented this methodology in a software called CoDACom (Community Detection Algorithm Comparator, codacom.greyc.fr) that also provides many community detection tools
Yang, Bo. "Analyses bioinformatiques et classements consensus pour les données biologiques à haut débit." Thesis, Paris 11, 2014. http://www.theses.fr/2014PA112250/document.
Full textIt is thought to be more and more important to solve biological questions using Bioinformatics approaches in the post-genomic era. This thesis focuses on two problems related to high troughput data: bioinformatics analysis at a large scale, and development of algorithms of consensus ranking. In molecular biology and genetics, RNA splicing is a modification of the nascent pre-messenger RNA (pre-mRNA) transcript in which introns are removed and exons are joined. The U2AF heterodimer has been well studied for its role in defining functional 3’ splice sites in pre-mRNA splicing, but multiple critical problems are still outstanding, including the functional impact of their cancer-associated mutations. Through genome-wide analysis of U2AF-RNA interactions, we report that U2AF has the capacity to define ~88% of functional 3’ splice sites in the human genome. Numerous U2AF binding events also occur in other genomic locations, and metagene and minigene analysis suggests that upstream intronic binding events interfere with the immediate downstream 3’ splice site associated with either the alternative exon to cause exon skipping or competing constitutive exon to induce inclusion of the alternative exon. We further build up a U2AF65 scoring scheme for predicting its target sites based on the high throughput sequencing data using a Maximum Entropy machine learning method, and the scores on the up and down regulated cases are consistent with our regulation model. These findings reveal the genomic function and regulatory mechanism of U2AF, which facilitates us understanding those associated diseases.Ranking biological data is a crucial need. Instead of developing new ranking methods, Cohen-Boulakia and her colleagues proposed to generate a consensus ranking to highlight the common points of a set of rankings while minimizing their disagreements to combat the noise and error for biological data. However, it is a NP-hard questioneven for only four rankings based on the Kendall-tau distance. In this thesis, we propose a new variant of pivot algorithms named as Consistent-Pivot. It uses a new strategy of pivot selection and other elements assignment, which performs better both on computation time and accuracy than previous pivot algorithms
Viadé, Julià Jordi. "Relación de los territorios vasculares a nivel plantar del antepie con las zonas de más incidencia de úlceras en pacientes diabéticos." Doctoral thesis, Universitat Autònoma de Barcelona, 2020. http://hdl.handle.net/10803/671384.
Full textLa diabetes mellitus, constituye una de las principales causas de mortalidad en los países desarrollados, observándose un incremento progresivo, de proporciones epidémicas, en países en vías de desarrollo. La aparición de una úlcera en el pie representa uno de los problemas de salud más importantes para los pacientes diabéticos, siendo una de las complicaciones más frecuentes, complejas y de alto coste. Debido a la relevancia de la circulación sanguínea en el pie de pacientes afectos de DM, se consideró valorar si la existencia de factores anatómicos que pudieran condicionar la vascularización arterial. Los objetivos de este estudio fueron: evaluar la clínica y la evolución de estos pacientes, así como ampliar un algoritmo existente para que permitiera un correcto manejo de estos pacientes. Por otra parte, estudiar la vascularización arterial del antepie y la importancia de las anastomosis en esta región, y si el concepto de ‘angiosoma de Taylor y Palmer’ era aplicable a la zona plantar del antepie. Estudio con 75 pacientes diabéticos, con ulcera plantar, a nivel de las cabezas metatarsales, por ser esta un área donde se concentran altas presiones durante la deambulación. Para ello se ha realizado un estudio clínico que contribuya a un mejor conocimiento sobre el manejo y el tratamiento de las úlceras ubicadas en la región plantar del antepie en pacientes diabéticos y un estudio anatómico con 10 extremidades inferiores, donde se realizó la disección anatómica convencional para la identificación de las arterias de la pierna y del pie y se evaluó la vascularización arterial de esta zona. El tratamiento se ha realizado según el algoritmo, de evaluación, diagnóstico y tratamiento, también objeto de estudio, así como la aplicación de los diferentes tipos de descargas y/o pequeños gestos quirúrgicos, con el objetivo fundamental de minimizar el número de amputaciones y sus consecuencias. En la serie objeto de estudio, sólo en un 5,3% se tuvo que realizar una amputación menor. El nuevo algoritmo, vinculado a siete algoritmos específicos, permite seguir paso a paso todos los detalles, por este motivo lo hemos llamado ‘algoritmo de algoritmos’ que incluye el cribaje neuroisquémico, pautas para la obtención de muestras de cultivo microbiológico, diagnostico de osteomielitis, tratamiento antibiótico, aplicación de descargas, cura tópica y técnicas quirúrgicas. Si bien no podemos concluir con una aplicabilidad del concepto angiosoma en este estudio, consideramos de gran relevancia las anastomosis entre las diferentes arterias que irrigan el pie. La irrigación arterial del pie tiene importancia tanto para el diagnóstico como para los diferentes tratamientos que se puedan realizar. Las arterias metatarsianas plantares tienen anastomosis con las metatarsianas dorsales, cuyo flujo sanguíneo procede de la arteria dorsal del pie (pedia). Estas anastomosis son habitualmente en número de dos para cada conexión. Además, se deben tener en cuenta otras anastomosis entre las arterias plantares y la dorsal del pie, como es el arco plantar profundo. Todas estas anastomosis justifican la posibilidad de flujos sanguíneos alternantes. La irrigación de la cabeza de los metatarsianos depende fundamentalmente de ramas de las arterias metatarsianas plantares.
Diabetes mellitus is one of the main causes of mortality in developed countries, observing a progressive increase, of epidemic proportions, in developing countries. The appearance of a foot ulcer represents one of the most important health problems for diabetic patients, being one of the most frequent, complex and high-cost complications. Due to the relevance of blood circulation in the foot of patients affected by DM, it was considered to assess whether the existence of anatomical factors that could condition arterial vascularization. The objectives of this study were to evaluate the clinic and the evolution of these patients, as well as to enlarge an existing algorithm so that it allowed a correct management of these patients. On the other hand, to study the arterial vascularization of the forefoot and the importance of anastomoses in this region, and if the concept of ‘Taylor and Palmer angiosome’ was applicable to the plantar area of the forefoot. Study with 75 diabetic patients, with plantar ulcer, at the level of the metatarsal heads, as this is an area where high pressures are concentrated during ambulation. For this, a clinical study has been carried out that contributes to a better knowledge of the management and treatment of ulcers located in the plantar region of the forefoot in diabetic patients and an anatomical study with 10 lower extremities, where conventional anatomical dissection was performed to the identification of the leg and foot arteries and the arterial vascularization of this area was evaluated. The treatment has been carried out according to the algorithm, evaluation, diagnosis and treatment, also the object of study, as well as the application of the different types of discharges and / or small surgical gestures, with the fundamental objective of minimizing the number of amputations and their consequences. In the series under study, only 5.3% had to undergo a minor amputation. The new algorithm, linked to seven specific algorithms, allows us to follow all the details step by step, for this reason we have called it ‘algorithm algorithm’ that includes neuroischemic screening, guidelines for obtaining samples of microbiological culture, diagnosis of osteomyelitis, antibiotic treatment, application of discharges, topical cure and surgical techniques. Although we cannot conclude with an applicability of the angiosome concept in this study, we consider anastomoses of different arteries supplying the foot of great relevance. The arterial irrigation of the foot is important for the diagnosis and for the different treatments that can be carried out. The plantar metatarsal arteries have anastomoses with the dorsal metatarsals whose blood flow comes from the dorsal artery of the foot (pedia). These anastomoses are usually two in number for each connection. In addition, other anastomoses between the plantar and dorsal arteries of the foot must be taken into account, such as the deep plantar arch. All of these anastomoses justify the possibility of alternating blood flows. The irrigation of the metatarsal head depends mainly on branches of the plantar metatarsal arteries.
Lo, Moustapha. "Application des architectures many core dans les systèmes embarqués temps réel." Thesis, Université Grenoble Alpes (ComUE), 2019. http://www.theses.fr/2019GREAM002/document.
Full textTraditional single-cores are no longer sufficient to meet the growing needs of performance in avionics domain. Multi-core and many-core processors have emerged in the recent years in order to integrate several functions thanks to the resource sharing. In contrast, all multi-core and many-core processorsdo not necessarily satisfy the avionic constraints. We prefer to have more determinism than computing power because the certification of such processors depends on mastering the determinism.The aim of this thesis is to evaluate the many-core processor (MPPA-256) from Kalray in avionic context. We choose the maintenance function HMS (Health Monitoring System) which requires an important bandwidth and a response time guarantee. In addition, this function has also parallelism properties. It computes data from sensors that are functionally independent and, therefore their processing can be parallelized in several cores. This study focuses on deploying the existing sequential HMS on a many-core processor from the data acquisition to the computation of the health indicators with a strongemphasis on the input flow.Our research led to five main contributions:• Transformation of the global existing algorithms into a real-time ones which can process data as soon as they are available.• Management of the input flow of vibration samples from the sensors to the computation of the health indicators, the availability of raw vibration data in the internal cluster, when they are consumed and finally the workload estimation.• Implementing a lightweight Timing measurements directly on the MPPA-256 by adding timestamps in the data flow.• Software architecture that respects real-time constraints even in the worst cases. The software architecture is based on three pipeline stages.• Illustration of the limits of the existing function: our experiments have shown that the contextual parameters of the helicopter such as the rotor speed must be correlated with the health indicators to reduce false alarms
Bonichon, Nicolas. "Quelques algorithmes entre le monde des graphes et les nuages de points." Habilitation à diriger des recherches, Université Sciences et Technologies - Bordeaux I, 2013. http://tel.archives-ouvertes.fr/tel-00922501.
Full textAyed, Hedi. "Approches de résolution multiobjective séquentielle et parallèle pour les réseaux de transports multimodaux." Thesis, Metz, 2011. http://www.theses.fr/2011METZ029S/document.
Full textThe focus of this thesis is about multi-modal, multi-objective and time-dependent in passengers transport networks. We propose itineraries processing solutions that satisfy the user needs, as much as possible. The first part of our contributions begins with the definition of the transfer-graph model that is consistent with the distributed nature of multi-modal transport networks. Based on this model, we propose several itineraries processing algorithms. We have been interested, in a second part of this thesis, in developing multi-objective solutions to satisfy more constraints at the same time. We first experimented the time-dependent version of an exact algorithm based on Martins. We then proposed a solution based on a genetic algorithm. Both of these approaches are limited because of either excessive time response or memory space limit. The hybrid algorithm which combines the speed of meta-heuristics and completeness of exact methods, provide better results
Ben, Aboud Hafssa. "Algorithmes pour de meilleures performances de TCP sur les liens satellites." Dijon, 2004. http://www.theses.fr/2004DIJOS010.
Full textZaghdoud, Radhia. "Hybridation d’algorithme génétique pour les problèmes des véhicules intelligents autonomes : applications aux infrastructures portuaires de moyenne taille." Thesis, Ecole centrale de Lille, 2015. http://www.theses.fr/2015ECLI0023/document.
Full textThe objective of our work is to develop a container assignment system for intelligent autonomous vehicles (AIVS) in a container terminal. Given the complexity of this problem, it was proposed to decompose it into three problems: The problem of dispatching containers to AIVS, the AIVS routing problem and the problem of scheduling containers to queues of AIVS. To achieve this goal, we developed in the first phase, a static system for multi-objective problem to optimize the total duration of the containers transportation, the waiting time of vehicles at loading points and the equilibrium of working time between vehicles. The approach used was the genetic algorithm (GA). This approach was applied to optimize only the assignment operation without influence on the choice of the path traveled by each AIV. An extension of this work was then made to improve the results found. For this purpose, a comparative study was carried out between three approaches: The first approach is the AG, the second approach is the GA and the Dijkstra algorithm (DIJK) that was used to find the shortest path for each vehicle and the third approach is the AG and DIJK and heuristic (HEUR) which was proposed to choose the nearest vehicle of each container. The numerical study showed the best performance of the AG & DJK & HEUR approach over the other two approaches. In the second phase of our project, the robustness of our system in a dynamic environment has been studied. A delay of the arrival of a ship at the port or malfunction of one of any equipment of the port can cause a delay of one of the operations of loading or unloading process. This will affect the container assignment operation. The idea was to add new containers to vehicles that are already unavailable. The traffic can also cause a delay in arrival of the vehicle at the position of the container or the unavailability of one of the paths crossing point. These cases were investigated experimentally, numerical results showed the robustness of our approach to dynamic case
Yahiaoui, Said. "Algorithmes et applications pour la coloration et les alliances dans les graphes." Thesis, Lyon 1, 2013. http://www.theses.fr/2013LYO10274.
Full textThis thesis investigates the algorithmic aspects and applications of two graph problems, namely, colorings and alliances. In the first part, we focus on two variants of the proper vertex coloring, the Grundy coloring and the strict strong coloring. We start by the study of Grundy number for regular graphs. We give a sufficient condition for d-regular graphs with sufficiently large girth to have Grundy number equals d + 1. Then, using graph homomorphism, we obtain a necessary and sufficient condition for d-regular graphs to have Grundy number at least k. Moreover, we characterize cubic graphs (3-regular) for which the Grundy number is d + 1, and present a linear-time algorithm to determine the Grundy number of any arbitrary cubic graph. Subsequently, based on the strict strong coloring, we present an approach for the problem of matching labeled trees. Using this coloring, we propose a new algorithm to deterministically decompose a tree into small components. This leads to an efficient algorithm to measure an accurate distance between unrooted unordered labeled trees. The second part is devoted to the alliances in graphs. We first propose a linear-time self-stabilizing algorithm for the minimal global offensive alliance set problem, under the synchronous distributed scheduler. Then, we give the first self-stabilizing algorithm for the minimal global powerful alliance set problem in arbitrary graphs. Moreover, we show how this algorithm can be adapted to find the minimal global powerful k-alliance and the minimal weighted global powerful alliance sets. We prove that all these algorithms converge in polynomial-time under the unfair distributed scheduler. Finally, based on the structural properties of the offensive alliance, we propose a solution to decentralize the signaling protocol SIP. This enables SIP applications in mobile ad hoc networks
Letsios, Dimitrios. "Politiques de gestion d'énergie et de température dans les systèmes informatiques." Thesis, Evry-Val d'Essonne, 2013. http://www.theses.fr/2013EVRY0016/document.
Full textNowadays, the enegy consumption and the heat dissipation of computing environments have emerged as crucial issues. Indeed, large data centers consume as muse electricity as a city while modern processors attain high temperatures degrading their performance and decreasing their reliability.. In this thesis, we study various energy and temperature aware scheduling problems and we focus on their complexity and approximability. A dominant technique for saving energy is by prosper scheduling of the jobs through the operating system combined with appropriate scaling of the processor's speed. This technique is referred to as speed scaling in the literature and its theoretical study was initiated by Yao, Demers and Shenker (FOCS'1995). In order to manage the thermal behavior of a computing device, we adaopt the approach of Chrobak, Dürr, Hurand and Robert (AAIM'2008). The main assumption is that some jobs are more CPU intensive than others and more heat is generated during their execution. Moreover, the cooling of a computing device occurs by introducing appropriate idle periods
Le, Berre Matthieu. "Optimisation de déploiement et localisation de cible dans les réseaux de capteurs." Thesis, Troyes, 2014. http://www.theses.fr/2014TROY0021/document.
Full textIn this thesis, a joint approach for deployment optimization and target tracking in sensor networks is developed. First, we have proposed a linear model to minimize the number of deployed sensors and maximize the accuracy of the localization. We have also implemented several multi-objective methods and proposed hybridization for some of them.We have also proposed a modification of the previous model, taking into account the indoor localization constraints. Two methods of the previous problem have been used, and a specific heuristic has been developed.Finally, two linear models taking into account coverage and connectivity have been proposed. A Branch and Bound algorithm has also been developed, considering a geometric lower bound and two properties to reduce the number of fathomed nodes
Deau, Raphaël. "Optimisation des séquences de pistes et des mouvements au sol sur les grands aéroports." Thesis, Toulouse, INPT, 2010. http://www.theses.fr/2010INPT0060/document.
Full textIn the last few years, many studies concerning air traffic delays have focused on ground traffic management at busy airports. However, the link between the aircraft taxiing stage and runway scheduling optimisation is still rarely considered. Performing optimal aircraft sequences on runways should allow us to enhance the taxiing stage, while applying calculated take-off slots and reducing globally the aircraft mean delay. In this thesis, an algorithm is first defined to compute optimal aircraft schedules on runways. It is then integrated into the ground traffic management process, modeled as a conflict resolution problem between aircraft. A deterministic method (using a branch and bound algorithm) and a stochastic method (using a genetic algorithm) are both used to try and solve this problem. Each of these methods can work with and without the consideration of optimal runway scheduling. The simulations carried out show that the anticipation of the optimal runway schedules can yield a significant delay reduction for airport ground traffic. The stochastic method provides the best solutions, especially for arriving aircraft, while the deterministic method remains a considerable option because of its very fast running time
Mouloua, Zerouk. "Ordonnancements coopératifs pour les chaînes logistiques." Phd thesis, Institut National Polytechnique de Lorraine - INPL, 2007. http://tel.archives-ouvertes.fr/tel-00606329.
Full textFoucaud, Florent. "Aspects combinatoires et algorithmiques des codes identifiants dans les graphes." Phd thesis, Université Sciences et Technologies - Bordeaux I, 2012. http://tel.archives-ouvertes.fr/tel-00766138.
Full textBrito, Deusdete de Sousa. "Cálculo da Frequência Instantânea Cardíaca Utilizando o Algoritmo LMS e uma Interface de Aquisição de Dados." Universidade Federal do Maranhão, 2002. http://tedebc.ufma.br:8080/jspui/handle/tede/318.
Full textConselho Nacional de Desenvolvimento Científico e Tecnológico
In this work we consider the calculation of the heart instantaneous frequency from the estimate of the weights, gotten through LMS algorithm, (Least Mean Squares) when functioning as spectrum analyzer. It is known that the electrocardiogram (ECG) is a signal that is characterized for a repetitive regularity, which can be called quasi-periodicity. We explore this characteristic to extract the instantaneous frequency of the referred signal. For this, we use the LMS as a spectral analyzer. We use as reference inputs pairs of sines and cosines, inside the frequency band where if it finds the frequency of the desired signal, namely, the heart frequency. The algorithm estimates the frequency desired in real time, with the signal acquired through a data acquisition interface Intel 80C31. The results obtained show that the algorithm can be recommended for this purpose, as besides being easily implemented and generating small computational load it estimates the heart instantaneous frequency with a relative mean error of 0.025 which represent a difference of 18.89% between the two methods.
Neste trabalho propomos o cálculo da frequência instantânea cardíaca a partir da estimativa do espectrograma dos pesos sinápticos, obtidos através do algoritmo LMS, (Least Mean Square) quando funcionando como analisador de espectro. Sabe-se que o eletrocardiograma (ECG) é um sinal que se caracteriza por uma regularidade repetitiva, que se pode chamar quasiperiodicidade. Exploramos aqui essa característica para extrair a frequência instantânea do referido sinal. Para isso, utilizamos o LMS como analisador de espectro. Utilizamos como entradas de referència pares de senos e cossenos, dentro da faixa de frequência em que se encontra a frequência do sinal desejado, no caso, a frequência cardíaca. O algoritmo estima a frequência desejada em tempo real, com obtenção do sinal através de uma interface de aquisição de dados Intel 80C31. Os resultados obtidos mostraram que o algoritmo pode ser recomendado pra esta finalidade, pois além de ser facilmente implementável e por gerar pequena carga computacional ele estimou a frequência instantânea cardíaca com um erro relativo médio de 0.025 que representa uma diferença de 18.89% entre os dois métodos.
Leroux, Louis. "Algorithmes pour les polynômes lacunaires." Phd thesis, Université de Caen, 2011. http://tel.archives-ouvertes.fr/tel-00580656.
Full textHouissa, Asma. "Les algorithmes d’apprentissage pour l’aide au stationnement urbain." Thesis, Université Paris-Saclay (ComUE), 2018. http://www.theses.fr/2018SACLV001.
Full textThe objective of this thesis is to develop, to integrate and to test a new algorithmic approach to help parking in urban centers.Given the different types of deployed infrastructure : from input-output detection of vehicles to time variation of the number of available places within each street segment, we propose an efficient method to determine an itinerary that minimize the time expectation to find an available place and also to predict the availability of the parking places.We have chosen an urban area and we have considered it as a set of parking resources called street segments. More exactly, this urban area is considered as a graph where the vertexes represent the crossroads and the arcs represent the street segments. The essential parameters of our urban area model are the parking capacity and the time crossing of each street segment. The originality and the innovation of our approach are based on two principles.The first one is the guidance as a resource, i.e., it means that the proposed itinerary is not the one that lead to an available parking place but rather the one that minimized the time expectation to find an available parking place. In order to achieve that we determine, in a an area centered on a given destination, the itinerary to follow by the vehicle in order minimize its time expectation to find an available parking place as quickly aspossible.We have designed and realized a reinforcement learning algorithm based on the LRI method (Linear Reward Inaction) and a Monte Carlo method to minimize the time expectation to find an available parking place in the urban area. We have compared this algorithm to a global approach based on tree evaluation with bounded depth. The second principle is based on the prediction of the parking places by homogeneous time period where we are not interestedon a parking place in real time but rather on the parking places byarea. In other terms, the system predict the potential available parkingplaces by resource for the next time periods. Thus, we don’t aim to predict the availability of each parking place, i.e., each resource is considered as stock area and its availability is assessed in major part in function of the street segment input-output flow. For this principle, we have determined by a learning algorithm the probability that there is at least one available parking place in a street segment within a given time. The major data needed to compute this probability are the time series of input-output of each vehicle in street intersections, and the variation of the available parking places through the time.We have evaluated the performance of this approach by simulation based on random generated data and on real data of a district in Versailles
Flouvat, Frédéric. "Vers des solutions adaptatives et génériques pour l'extraction de motifs intéressants dans les données." Phd thesis, Université Blaise Pascal - Clermont-Ferrand II, 2006. http://tel.archives-ouvertes.fr/tel-00844480.
Full textCaruso, Sandrine. "Algorithmes et généricité dans les groupes de tresses." Phd thesis, Université Rennes 1, 2013. http://tel.archives-ouvertes.fr/tel-00881511.
Full textSouza, Francisco das Chagas de. "Algoritmos adaptativos LMS normalizados proporcionais." Florianópolis, 2012. http://repositorio.ufsc.br/xmlui/handle/123456789/96392.
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Neste trabalho, um novo algoritmo LMS normalizado proporcional (PNLMS) é proposto. Tal algoritmo usa fatores de ativação individuais para cada coeficiente do filtro adaptativo, em vez de um fator de ativação global como no algoritmo PNLMS padrão. Os fatores de ativação individuais do algoritmo proposto são atualizados recursivamente a partir dos correspondentes coeficientes do filtro adaptativo. Essa abordagem conduz a uma melhor distribuição da energia de adaptação entre os coeficientes do filtro. Dessa forma, para respostas ao impulso com elevada esparsidade, o algoritmo proposto, denominado algoritmo PNLMS com fatores de ativação individuais (IAF PNLMS), atinge maior velocidade de convergência do que os algoritmos PNLMS padrão e PNLMS melhorado (IPNLMS). Também, uma metodologia de modelagem estocástica dos algoritmos da classe PNLMS é apresentada. Usando essa metodologia, obtém-se um modelo estocástico que prediz satisfatoriamente o comportamento do algoritmo IAF PNLMS tanto na fase transitória quanto na estacionária. Através de simulações numéricas, a eficácia do modelo proposto é verificada. Adicionalmente, uma versão melhorada do algoritmo IAF PNLMS, denominada EIAF PNLMS, é proposta neste trabalho, a qual usa uma estratégia de redistribuição de ganhos durante o processo de aprendizagem, visando aumentar os ganhos atribuídos aos coeficientes inativos quando os ativos aproximam-se da convergência. Resultados de simulação mostram que tal estratégia de redistribuição melhora significativamente as características de convergência do algoritmo
Do, Viet Phuong. "Développement et applications de méthodes bioinformatiques pour l'identification des répétitions en tandem dans les structures des protéines." Thesis, Montpellier, 2016. http://www.theses.fr/2016MONTT072.
Full textIn general, protein structures can be divided into: repetitive and aperiodic structures. Most of the aperiodic structures are globular proteins. The repetitive proteins contain arrays of repeats that are adjacent to each other, called Tandem Repeats (TRs). Proteins containing TRs are abundant and have fundamental functional importance. Numerous studies demonstrated the involvement of such TR-containing proteins in human diseases. Furthermore, genetic instability of these regions can lead to emerging infection threats. Additionally, TR-containing structures have generated significant interest with respect to protein design as they can make excellent scaffolds for specific recognition of target molecules. Therefore, the discovery of these domains, understanding of their sequence–structure–function relationship promises to be a fertile direction for research.The growth of structural genomics initiatives, in combination with improvements in crystallographic and NMR techniques aimed at non-globular proteins, has resulted in an increase in structurally elucidated TR proteins. This has necessitated the development of classification schemes. Structural repeats were broadly divided into five classes mainly based on repeat length; Class I – crystalline aggregates; Class II – fibrous structures such as collagen; Class III – elongated structures where the repetitive units require each other for structural stability such as solenoid proteins; Class IV – closed repetitive structures, such as TIM-barrels and Class V – bead on a string structures such as tandems of Ig-fold domains. Despite this progress, the majority of bioinformatics approaches have focused on non-repetitive globular proteins.In recent years, efforts have been made to develop bioinformatics tools for the detection and analysis of repetitive elements in protein structures (3D TRs). Depending on the size and character of the repeats, some methods perform better than others, but currently no best approach exists to cover the whole range of repeats. This served as a motivation for the development of our method called the TAndem PrOtein detector (TAPO). TAPO exploits, periodicities of atomic coordinates and other types of structural representation, including strings generated by conformational alphabets, residue contact maps, and arrangements of vectors of secondary structure elements. Currently, seven feature based scores produced by TAPO are combined using a Support Vector Machine, producing a score to enable the differentiation between proteins with and without 3D TRs. TAPO shows an improved performance over other cutting edge methods, achieving 94% sensitivity and 97% specificity on the current benchmark. The development of TAPO provided new opportunities for large scale analysis of proteins with 3D TRs. In accordance with our analysis of PDB using TAPO, 19% of proteins contain 3D TRs. The large scale analysis of the 3D TR structures in PDB also allows us to discover several new types of TR structures that were absent in the existing classification. Some of them are described in the thesis manuscript. This suggests that TAPO can be used to regularly update the collection and classification of existing repetitive structures. In particular, a comprehensive analysis of 3D TRs related to Rossmann Fold (RF) was undertaken. Our special interest in RFs was based on the observation that many proteins with RFs represent borderline cases between repetitive and non-repetitive structures. In principle, α-helix-β-strand units of RFs should have a strong potential to stack one over the other, forming repetitive structures. To probe the question of how frequently RFs form long arrays of stacked repeats, we selected by using TAPO known RF-containing structures and classified them. Our analysis shows that typical RFs cannot be clearly defined as repetitive, rather they are part of globular structures with up to 3 αβ-repeats. We provide some explanations for this surprising observation
Delaroque, Aurélie. "Élaboration d’un outil numérique pour la réduction et l’optimisation des mécanismes cinétiques pour les systèmes de combustion." Thesis, Sorbonne université, 2018. http://www.theses.fr/2018SORUS417.
Full textIn the modeling of a combustion process, obtention of global data such as flame speed can, under certain circumstances, be achieved through extremely reduced mechanisms. On the contrary, prediction of detailed data such as polluant species requires the use of detailed kinetic mechanisms involving many chemical species. Due to the size and to the presence of many differents time scales, the integration of those models to complex numerical simulations is a non trivial task. A reduction tool based on Directed Relation Graph and sensitivity analysis methods is proposed to tackle this issue. Reduced mechanisms fitting user defined tolerances for quantities of interest such as global (flame speed, ignition delay, etc) and detailed data (concentration profiles) are automatically generated. The reduction process is paired up with an optimisation of reaction rates through a genetic algorithm to make up for the error induced by the loss of information. This process can use both numerical and experimental reference entries. The complete numerical tool has been tested on several canonical configurations for several fuels (methane, ethane and n-heptane) and reduction rates up to 90% have been observed
Bonnefoy, Antoine. "Elimination dynamique : accélération des algorithmes d'optimisation convexe pour les régressions parcimonieuses." Thesis, Aix-Marseille, 2016. http://www.theses.fr/2016AIXM4011/document.
Full textApplications in signal processing and machine learning make frequent use of sparse regressions. Resulting convex problems, such as the LASSO, can be efficiently solved thanks to first-order algorithms, which are general, and have good convergence properties. However those algorithms suffer from the dimension of the problem, which impose the complexity of their iterations. In this thesis we study approaches, based on screening tests, aimed at reducing the computational cost at the iteration level. Such approaches build upon the idea that it is worth dedicating some small computational effort to locate inactive atoms and remove them from the dictionary in a preprocessing stage so that the regression algorithm working with a smaller dictionary will then converge faster to the solution of the initial problem. We believe that there is an even more efficient way to screen the dictionary and obtain a greater acceleration: inside each iteration of the regression algorithm, one may take advantage of the algorithm computations to obtain a new screening test for free with increasing screening effects along the iterations. The dictionary is henceforth dynamically screened instead of being screened statically, once and for all, before the first iteration. Our first contribution is the formalisation of this principle and its application to first-order algorithms, for the resolution of the LASSO and Group-LASSO. In a second contribution, this general principle is combined to active-set methods, whose goal is also to accelerate the resolution of sparse regressions. Applying the two complementary methods on first-order algorithms, leads to great acceleration performances
Abbas, Boushra. "Méthode de Newton régularisée pour les inclusions monotones structurées : étude des dynamiques et algorithmes associés." Thesis, Montpellier, 2015. http://www.theses.fr/2015MONTS250/document.
Full textThis thesis is devoted to finding zeroes of structured maximal monotone operators, by using discrete and continuous dissipative dynamical systems. The solutions are obtained as the limits of trajectories when the time t tends towards infinity.We pay special attention to the dynamics that are obtained by Levenberg-Marquardt regularization of Newton's method. We also revisit the approaches based on some related dynamical systems.In a Hilbert framework, we are interested in finding zeroes of a structured maximal monotone operator M = A + B, where A is a general maximal monotone operator, and B is monotone and locally Lipschitz continuous. We introduce discrete and continuous dynamical systems which are linked to Newton's method. They involve separately B and the resolvents of A, and are designed to splitting methods. Based on the Minty representation of A as a Lipschitz manifold, we show that these dynamics can be formulated as differential systems, which are relevant to the Cauchy-Lipschitz theorem. We focus on the particular case where A is the subdifferential of a convex lower semicontinuous proper function, and B is the gradient of a convex, continuously differentiable function. We study the asymptotic behavior of trajectories. When the regularization parameter does not tend to zero too rapidly, and by using Lyapunov asymptotic analysis, we show the convergence of trajectories. Besides, we show the Lipschitz continuous dependence of the solution with respect to the regularization term.Then we extend our study by considering various classes of dynamical systems which aim at solving inclusions governed by structured monotone operators M = $partialPhi$+ B, where $partialPhi$ is the subdifferential of a convex lower semicontinuous function, and B is a monotone cocoercive operator. By a Lyapunov analysis, we show the convergence properties of the orbits of these systems. The time discretization of these dynamics gives various forward-backward splittingmethods (some new).Finally, we focus on the study of the asymptotic behavior of trajectories of the regularized Newton dynamics, in which we introduce an additional vanishing Tikhonov-like viscosity term.We thus obtain the asymptotic selection of the solution of minimal norm
Jin, Yinfu. "Identification Les paramètres des sols et sélection de modèles de comportement en utilisant des algorithmes génétiques." Thesis, Ecole centrale de Nantes, 2016. http://www.theses.fr/2016ECDN0017.
Full textThe subject of this thesis is the identification of soil parameters and the selection of constitutive models using genetic algorithms. First, various optimization methods for identifying soil parameters are studied. Then, a real - coded genetic algorithm (RCGA) has been developed to improve the performance of genetic algorithms (GA) for identifying soil parameters. Subsequently, the RCG A is employed to construct a formula for predicting the compressibility of remolded clays by using an evolutionary polynomial regression ( EPR ) based on the initial void ratio e 0 , the liquid limit w L and the plastic index I P . Then, an efficient procedure fo r identifying the necessary parameters of soft structured clay s is propose d by employing the enhanced RCGA coupled with an advanced anisotropic elasto - viscoplastic model. This approach is then validated and several applications are developed to demonstrate that the procedure can be used with a reduction of the testing cost . F inally , an appropriate model of sand with the necessary features based on conventional tests and with an easy way of identifying parameters for geotechnical applications by employ ing th e RCGA and different sand models is selected. A discussion on nonlinear plastic stress - strain hardening , the incorporation of the critical state concept with interlocking effect , test types and numbers , and necessary strain level for the selection and use of sand models concludes the thesis
Lambein, Patrick. "Consensus de moyenne dans les réseaux dynamiques anonymes : Une approche algorithmique." Thesis, Institut polytechnique de Paris, 2020. http://www.theses.fr/2020IPPAX103.
Full textCompact and cheap electronic components announce the near-future development of applications in which networked systems of autonomous agents are made to carry over complex tasks. These, in turn, depend on a small number of coordination primitives, which need to be programmatically implemented into potentially low-powered, and computationally limited, agents.Such applications include for example the coordination of the collective motion of mobile and vehicular networks, the distributed aggregation and processing of data measured locally in sensor networks, and the on-line repartition of processing load in the computer farms powering wide-scale services. As they address constraints that are not specific to the digital nature of the network such primitives also serve to model complex behavior of natural systems, such as flocks and neural networks.This monograph focuses on providing distributed algorithms that asymptotically compute the average of initial values, initially present at each agent of a networked system with time-varying communication links and in the absence of centralized control. Additionally, we consider the weaker problem of getting the agents to asymptotically agree on any value within the initial bounds. We focus on locally implementable algorithms, which leverage no information beyond what the agents can acquire by themselves, and which need no bootstrapping mechanism like a global start signal or a leader agent.We provide distributed average consensus algorithms that operate over dynamic networks given different local assumptions. These algorithms are computationally simple and operate in polynomial time in the number of agents.For bidirectional communications, we give a deterministic algorithm which asymptotically computes the average as long as the network never becomes permanently disconnected. For the general case of asymmetric communications, we provide a stabilizing Monte Carlo algorithm that is efficient in bandwidth and memory and operates in linear time, along with an extension by which the algorithm can be made to uniformly terminate over any connected network in which agents may start asynchronously.This contrasts with a plethora of results and techniques in which agents are provided external information – the size of the system, a bound over their degree, – helped with exogenous symmetry breaking – a leader agent, unique identifiers, – or where the network is expected to conform to a specific shape – a ring, a a complete network, a regular graph. Indeed, because very different networks may look alike to the agents, they are limited in what they can learn locally, and many functions are impossible to compute in a fully distributed manner without assuming some structure in the network or additional symmetry-breaking device. Given these stringent constraints, our contribution is to offer algorithms whose validity depends uniquely on local and instantaneous conditions. In the bidirectional model, we show that anonymous deterministic agents can asymptotically compute the average in polynomial time. For the general model of directed interactions, we allow agents to consult random oracles. Under those conditions, full information protocols are capable of solving any problem, and so we focus on the spatial complexity and tolerance to a lack of initial coordination in the agents, while offering stronger termination guarantees than in the bidirectional case. Beyond the fact that locally implementable algorithms are eminently desirable, our study contributes to mapping the limits that local interactions impose on networks
Maniu, Silviu. "Gestion des données dans les réseaux sociaux." Thesis, Paris, ENST, 2012. http://www.theses.fr/2012ENST0053/document.
Full textWe address in this thesis some of the issues raised by the emergence of social applications on the Web, focusing on two important directions: efficient social search inonline applications and the inference of signed social links from interactions between users in collaborative Web applications. We start by considering social search in tagging (or bookmarking) applications. This problem requires a significant departure from existing, socially agnostic techniques. In a network-aware context, one can (and should) exploit the social links, which can indicate how users relate to the seeker and how much weight their tagging actions should have in the result build-up. We propose an algorithm that has the potential to scale to current applications, and validate it via extensive experiments. As social search applications can be thought of as part of a wider class of context-aware applications, we consider context-aware query optimization based on views, focusing on two important sub-problems. First, handling the possible differences in context between the various views and an input query leads to view results having uncertain scores, i.e., score ranges valid for the new context. As a consequence, current top-k algorithms are no longer directly applicable and need to be adapted to handle such uncertainty in object scores. Second, adapted view selection techniques are needed, which can leverage both the descriptions of queries and statistics over their results. Finally, we present an approach for inferring a signed network (a "web of trust")from user-generated content in Wikipedia. We investigate mechanisms by which relationships between Wikipedia contributors - in the form of signed directed links - can be inferred based their interactions. Our study sheds light into principles underlying a signed network that is captured by social interaction. We investigate whether this network over Wikipedia contributors represents indeed a plausible configuration of link signs, by studying its global and local network properties, and at an application level, by assessing its impact in the classification of Wikipedia articles.javascript:nouvelleZone('abstract');_ajtAbstract('abstract')
Maziere, Florian. "Modèles de parallélisme pour les métaheuristiques multi-objectifs." Thesis, Reims, 2019. http://www.theses.fr/2019REIMS002/document.
Full text.Many academic and industrial optimization problems are multi-objective and have been of particular interest to researchers in recent years. These problems usually do not have a single optimal solution but a set of best trade-off solutions which form the so-called Pareto front in the objective space. In order to approximate the Pareto front, multi-objective evolutionary algorithms (MOEAs) have been largely investigated in the fields of continuous and combinatorial optimization. Contrary to some classical algorithms, MOEAs have the ability to provide a number of solutions in one single run and are less sensitive to the shape of the Pareto front.As they often require a high amount of computing resources to explore large portions of the search space and handle complex real-life constraints, MOEAs could greatly benefit from today's high-performance computing architectures. Although significant progress has been made in recent years in the design and improvement of parallel models for evolutionary algorithms, most of these models have limited scalability and ability to solve various problems. In fact, solving multi-objective combinatorial optimization problems efficiently on a large number of processors remains a challenge today.This thesis aims to propose an island model which is based on objective space division. The main features of the proposed model are the following (i) An organizer has a global view of the current search via a global archive (ii) Asynchronous cooperation between islands, especially for the exchange of local archives with the organizer to limit model overheads (iii)Control islands to guide the exploration of the search space and improve diversity (iv) A periodic use of a specific local search procedure to improve convergence. Extensive experiments have been conducted to evaluate the performance of the approach and more particularly of each component in the resolution of two classical combinatorial problems, the travelling salesman problem and quadratic assignment problem. Extensibility and quality of the solutions are analyzed compared to state-of-the-art parallel models
Ouattara, Yacouba. "Gestion de l'énergie et de la connectivité dans les réseaux de capteurs sans fil statiques et mobiles." Thesis, Besançon, 2015. http://www.theses.fr/2015BESA2046/document.
Full textA number of works based on wireless sensor networks are interested in the energy management of these sensors. This energy is in fact a critical factor in the operation of these networks. Proper construction of sensor clusters is a great way to minimize the consumption of this energy. The problems related to these networks and often lies in their lifetime but also in the need to maintain connectivity between all transducers. These two aspects are closely linked. In this thesis, we focused on these two aspects in the context of static sensor networks but also of mobile sensors.We propose, as a _rst step, a hybrid algorithm for setting up clusters and the management of theseclusters. The uniqueness of this solution lies in the establishment of geographic areas for designation fcluster heads but also in transmission, in the exchanged messages, the amount of remaining energy on the sensors. Thus, the sensor data will designate the cluster heads and their successors will determine the thresholds for other sensors and for their operation. The algorithm is tested through many simulations. The second part of the work is to adapt our _rst algorithm for mobile sensor networks. We a_ect the trajectory of sensors to maintain connectivity and reduce energy consumption. For this, we are guided echo-location practiced by bats. We're interested in changing and dynamic topology in sensor networks. We analyzed the loss of energy as a function of the distance and the power transmission between the nodes and the head cluster. We also evaluate our algorithm on sensors that have a random move. We apply these algorithms to a _eet of surveillance drones simulation
Yakoubi, Zied. "Détection et évaluation des communautés dans les réseaux complexes." Thesis, Paris 13, 2014. http://www.theses.fr/2014PA132045/document.
Full textIn this thesis we focus, on one hand, on community detection in complex networks, and on the other hand, on the evaluation of community detection algorithms. In the first axis, we are particularly interested in Leaders driven community detection algorithms. First, we propose an enrichment of LICOD : a framework for building different leaders-driven algorithms. We instantiate different implementations of the provided hotspots. Second, we propose an extension of LICOD, we call it-LICOD. This extension introduces a self-validation step of all identified leaders. Experimental results of it-LICOD on real and artificial networks show that it outperform the initial LICOD approach. Obtained results are also competitive with those of other state-of-the art methods. Thirdly, we propose a semi-local centrality measure, called TopoCent, that address the problem of the irrelevance of local measures and high computational complexity of globalmeasures. We experimentally show that LICOD is often more efficient with TopoCent than with the other classical centrality measures. In the second axis, we propose two task-based community evaluation methods : CLE and PLE. We examine he hypothesis that the quality of community detection algorithms can be estimated by comparing obtained results in the context of other relevent tasks. The CLE approach, we use a data clustering task as a reference. The PLE method apply a link prediction task. We show that the experimentation of CLE and PLE methods gives new insights into the performance of community detection algorithms
Vernhes, Simon. "Décomposition des problèmes de planification de tâches basée sur les landmarks." Thesis, Toulouse, ISAE, 2014. http://www.theses.fr/2014ESAE0050/document.
Full textThe algorithms allowing on-the-fly computation of efficient strategies solving aheterogeneous set of problems has always been one of the greatest challengesfaced by research in Artificial Intelligence. To this end, classical planningprovides to a system reasoning capacities, in order to help it to interact with itsenvironment autonomously. Given a description of the world current state, theactions the system is able to perform, and the goal it is supposed to reach, a plannercan compute an action sequence yielding a state satisfying the predefined goal. Theplanning problem is usually intractable (PSPACE-hard), however some propertiesof the problems can be automatically extracted allowing the design of efficientsolvers.Firstly, we have developed the Landmark-based Meta Best-First Search (LMBFS)algorithm. Unlike state-of-the-art planners, usually based on state-space heuristicsearch, LMBFS reenacts landmark-based planning problem decomposition. Alandmark is a fluent appearing in each and every solution plan. The LMBFSalgorithm splits the global problem in a set of subproblems and tries to find aglobal solution using the solutions found for these subproblems. Secondly, wehave adapted classical planning techniques to enhance the performance of ourbase algorithm, making LMBFS a competitive planner. Finally, we have tested andcompared these methods