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Sûreté temporelle pour les systèmes temps réel multiprocesseurs / Temporal safety for real-time multiprocessor systemsFauberteau, Frédéric 12 December 2011 (has links)
Les systèmes temps réel à contraintes temporelles strictes sont caractérisés par des ensembles de tâches pour lesquelles sont connus l'échéance, le modèle d'arrivée (fréquence) et la durée d'exécution pire cas (WCET). Nous nous intéressons à l'ordonnancement de ces systèmes sur plate-forme multiprocesseur. Garantir le respect des échéances pour un algorithme d'ordonnancement est l'une des problématiques majeures de cette thématique. Nous allons plus loin en nous intéressant à la sûreté temporelle, que nous caractérisons par les propriétés (i) de robustesse et (ii) de viabilité. La robustesse consiste à proposer un intervalle sur les augmentations(i-a) de WCET et (i-b) de fréquence tel que les échéances soient respectées. La viabilité consiste cette fois à garantir le respect des échéances lors du relâchement des contraintes (ii-a) de WCET (réduction), (ii-b) de fréquence (réduction) et (ii-c) d'échéance(augmentation). La robustesse revient alors à tolérer l'imprévu, tandis que la viabilité est la garantie que l'algorithme d'ordonnancement n'est pas sujet à des anomalies suite à un relâchement de contraintes. Nous considérons l'ordonnancement en priorités fixes, où chaque occurrence d'une tâche est ordonnancée avec la même priorité. Dans un premier temps, nous étudions la propriété de robustesse dans les approches d'ordonnancement hors-ligne et sans migration (partitionnement). Nous traitons le cas des tâches avec ou sans partage de ressources. Dans un second temps, nous étudions la propriété de viabilité d'une approche d'ordonnancement en ligne avec migrations restreintes et sans partage de ressources / The hard real-time systems are characterized by sets of tasks for which are known the deadline, the arrival model (frequency) and the Worst-Case Execution Time (WCET). We focus on the scheduling of these systems on multiprocessor platforms. One of the main issues of this topic is to ensure that all deadlines are met. We go further by focusing on the temporal safety which we characterized by the properties of (i) robustness and (ii) sustainability. The robustness consists in providing an interval on the increases of (i-a) WCET and (i-b) frequency in such a way that the deadlines are met. The sustainability consists in ensuring that no deadline is missed when the following constraints are relaxed : (ii-a) WCET (decreasing), (ii-b) frequency (decreasing) and (ii-c) deadline (increasing). The robustness amounts to tolerate unexpected behaviors while the sustainability is the guarantee that the scheduling algorithm does not suffer from anomalies because of a relaxation of constraints. We consider fixed-priority scheduling for which any job of a task is scheduled with the same priority. Firstly, we study the property of robustness in off-line scheduling approaches without migration (partitioning). We deal with the case of tasks with or without shared resources. Secondly, we study the property of sustainability of an online restricted-migration scheduling approach without shared resources
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A simulation study of the robustness of prediction intervals for an independent observation obtained from a random sample from an assumed location-scale family of distributionsMakarova, Natalya January 1900 (has links)
Master of Science / Department of Statistics / Paul I. Nelson / Suppose that based on data consisting of independent repetitions of an experiment a researcher wants to predict the outcome of the next independent outcome of the experiment. The researcher models the data as being realizations of independent, identically distributed random variables { Xi, i=1,2,..n} having density f() and the next outcome as the value of an independent random variable Y , also having density f() . We assume that the density f() lies in one of three location-scale families: standard normal (symmetric); Cauchy (symmetric, heavy-tailed); extreme value (asymmetric.). The researcher does not know the values of the location and scale parameters. For f() = f0() lying in one of these families, an exact prediction interval for Y can be constructed using equivariant estimators of the location and scale parameters to form a pivotal quantity based on { Xi, i=1,2,..n} and Y. This report investigates via a simulation study the performance of these prediction intervals in terms of coverage rate and length when the assumption that f() = f0() is correct and when it is not.
The simulation results indicate that prediction intervals based on the assumption of normality perform quite well with normal and extreme value data and reasonably well with Cauchy data when the sample sizes are large. The heavy tailed Cauchy assumption only leads to prediction intervals that perform well with Cauchy data and is not robust when the data are normal and extreme value. Similarly, the asymmetric extreme value model leads to prediction intervals that only perform well with extreme value data. Overall, this study indicates robustness with respect to a mismatch between the assumed and actual distributions in some cases and a lack of robustness in others.
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Multiscale Change-point Segmentation: Beyond Step FunctionsGuo, Qinghai 03 February 2017 (has links)
No description available.
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Optimisation des correcteurs par les métaheuristiques. Application à la stabilisation inertielle de ligne de visée. / Controllers optimization with metaheuristics – Application to the ligne of sight stabilization problem.Feyel, Philippe 16 June 2015 (has links)
Dans l’industrie, l’automaticien doit concevoir une loi de commande unique qu’il valide sur un prototype unique, ayant un degré de robustesse suffisant pour satisfaire un cahier des charges complexe sur un grand nombre de systèmes. Pour cela, la méthodologie de développement qu’il emploie consiste en un processus itératif expérimental (phase d’essai-erreur), qui fait grandement appel à l’expérience de l’ingénieur. Dans cette thèse, on tente de rendre la méthodologie de synthèse des correcteurs des asservissements plus efficace car plus directe et donc moins couteuse en temps de développement en calculant un correcteur final (structuré) par une attaque directe de la spécification système haut niveau. La complexité des spécifications systèmes haut-niveau nous pousse à l’emploi des métaheuristiques : ces techniques d’optimisation ne nécessitent pas la formulation du gradient, la seule contrainte étant la possibilité d’évaluer la spécification. Ainsi avons-nous proposé dans ce travail de reformuler les problèmes de commande robuste pour l’optimisation stochastique : on montre dans ce travail comment on peut synthétiser des correcteurs structurés à partir de problématiques de type H ou -synthèse et on montre que l’intérêt de l’approche formulée réside dans sa flexibilité et la prise en compte de contraintes « exotiques » complexes ; les algorithmes évolutionnaires s’avérant très performants et compétitifs, nous avons finalement développé sur cette base une méthode originale de synthèse de correcteurs structurés et robustes vis-à-vis de critères d’optimisation de forme quelconque. La validation de ces travaux a été réalisée sur des exemples industriels de viseurs. / In the industrial framework, the control engineer must design a unique control law that valid on a single prototype, with a sufficient degree of robustness to satisfy a complex specification on many systems. For that purpose, his development methodology consists of an experimental iterative process (trial and error phase), which relies heavily on the experience of the engineer. In this thesis, we try to make the methodology for computing controllers more efficient and more direct with a less costly development time by calculating a final structured controller by a direct optimization on the high level specification.The complexity of high-level specifications pushes us to the use of metaheuristics: these optimization techniques do not require the formulation of the gradient, the only constraint being the possibility of evaluating the specification. Thus we proposed in this work to reformulate robust control problems for stochastic optimization: we show in this work how to synthesize structured controllers for control problems such H synthesis or -synthesis and show that the interest of the formulated approach lies in its flexibility and the consideration of exotic complex constraints. Evolutionary algorithms proving very effective and competitive, we finally developed on this basis a new method for synthesizing robust and structured controllers with respect to any form of optimization criteria. The validation of this work was carried out on the industrial example of the line of sight stabilization problem.
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Organizational resilience and the humanitarioan sector : Exploring Organizational Resilience in Policy and Practice within the United NationsÅslund, Robin January 2019 (has links)
The notion of ‘organizational resilience’ has risen exponentially in recent years; it is the ability of an organization to ‘bounce back’ and continue key functions during disruptive events. The rise follows the will to better face the unforeseen and complex adversity that modern times throws at organizations. This study, following a single-case exploratory research design, aims to establish knowledge regarding organizational resilience in the humanitarian sector; by exploring the policy and practice of the United Nations. The author builds an Analytical Framework based on the leading research in the field of organizational resilience, in order to grasp an understanding of the organization's different beliefs, capabilities, and proficiencies necessary to establish and maintain a resilient organization. Concluding with the statement that while there are areas of challenges, the humanitarian sector provides a case not only to scrutinize, but also to learn from.
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A Search-Based Approach for Robustness Testing of Web ApplicationsGurram, Karthik, Chappidi, Maheshwar Reddy January 2019 (has links)
Context: This thesis deals with the robustness testing of web applications on a different web browser using a Selenium WebDriver to automate the browser. To increase the efficiency of this automation testing, we are using a robustness method. Robustness method is a process of testing the behaviour of a system implementation under exceptional execution conditions to check if it still fulfils some robustness requirements. These robustness tests often apply random algorithms to select the actions to be executed on web applications. The search-based technique was used to automatically generate effective test cases, consisting of initial conditions and fault sequences. The success criteria in most cases: "if it does not crash or hang application, then it is robust". Problem: Software testing consumes a lot of time, labour-intensive to write test cases and expensive in a software development life cycle. There was always a need for software testing to decrease the testing time. Manual testing requires a lot of effort and hard work if we measure in terms of person per month [1]. To overcome this problem, we are using a search-based approach for robustness testing of web applications which can dramatically reduce the human effort, time and the costs related to testing. Objective: The purpose of this thesis is to develop an automated approach to carry out robustness testing of web applications focusing on revealing defects related to a sequence of events triggered by a web system. To do so, we will employ search-based techniques (e.g., NSGA-II algorithm [1]). The main focus is on Ericsson Digital BSS systems, with a special focus on robustness testing. The main purpose of this master thesis is to investigate how automated robustness testing can be done so that the effort of keeping the tests up to date is minimized when the functionality of the application changes. This kind of automation testing is well depended on the structure of the product being tested. In this thesis, the test object was structured in a way, which made the testing method simple for fault revelation and less time-consuming. Method: For this approach, a meta-heuristic search-based genetic algorithm is used to make efficiency for robustness testing of the web application. In order to evaluate the effectiveness of this proposed approach, the experimental procedure is adapted. For this, an experimental testbed is set up. The effectiveness of the proposed approach is measured by two objectives: Fault revelation, Test sequence length. The effectiveness is also measured by evaluating the feasible cost-effective output test cases. i Results:The results we collected from our approach shows that by reducing the test sequence length we can reduce the time consuming and by using the NSGA-2 algorithm we found as many faults as we can when we tested on web applications in Ericsson. Conclusion: The attempt of testing of web applications, was partly succeeded. This kind of robustness testing in our approach was strongly depended on the algorithm we are using. We can conclude that by using these two objectives, we can reduce the cost of testing and time consuming.
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Contrôle actif des vibrations en fraisage. / Control for vibration Phenomena in Mechanical Machining.Kochtbene, Feriel 21 December 2017 (has links)
Cette thèse commence avec un état de l’art des domaines d’études importants pour notre objectif (différentes techniques usuelles de réduction des vibrations en usinage, méthodes de contrôle actif) avant de valider le principe de contrôle actif du fraisage en se plaçant en repère fixe. On a alors développé un modèle d’état d’une poutre d’Euler Bernoulli perturbée en un point et corrigée en un autre via un actionneur piézoélectrique. Ce modèle a permis d’obtenir plusieurs compensateurs, suivant différentes stratégies de commande. Nous avons par la suite procédé, d’un point de vue expérimental, à l’étude sur un dispositif similaire à notre besoin d’un point de vue de l’actionnement et des ordres de grandeurs (amplification mécanique, gamme de fréquences etc.). Les stratégies de commande robustes que nous avons développé pour pouvoir atténuer les déplacements vibratoires de cette poutre ont conduit à des résultats concluants présentés dans le même chapitre, d’abord en simulation (qui nous a permis une étude comparative), avec ou sans la présence du processus d’usinage, puis expérimentalement. La robustesse de ces stratégies de commande a été étudiée (en simulation) en ajoutant des incertitudes au modèle étudié de différentes manières. Ensuite, nous avons identifié le modèle du système étudié, déterminé les correcteurs correspondants et testé ces derniers sur notre banc d’essai pour valider le bon fonctionnement des différentes stratégies de contrôle utilisées tout le long de cette thèse. Enfin, pour préparer un déploiement de ces stratégies en repère tournant (porte-outil de contrôle actif), nous avons modélisé et implémenté les mêmes démarches pour le cas où l’actionnement se situe en repère tournant et concerne deux axes simultanément, situés dans le plan XY du porte-outil. Nous avons d’abord étudié les vibrations transversales d’une poutre en rotation dans le cas général avant de négliger les phénomènes d’inertie et gyroscopique. En effet, on s’intéresse au contrôle actif du fraisage particulièrement dans les applications de finition, là où on utilise des outils longs de faibles diamètres. Les nouvelles expressions des deux fonctions de transfert de notre système usinant ont été déterminées pour obtenir sa représentation d’état, clé du contrôle actif. La projection du processus de coupe sur le repère tournant est indispensable pour effectuer les simulations du fraisage via le porte outil actif. Ce dernier chapitre met en relief les perspectives de cette thèse, à savoir le contrôle actif du fraisage quelque soit le type de l’opération ou du diamètre de l’outil avec un porte outil mécatronique destiné pour ce genre d’opérations. / This thesis deals with the fields of study which are important for our objective (different usual vibration reduction techniques in machining, active control methods) before validating the principle of active control of milling in a fixed reference. We then developed a state space model of an Euler Bernoulli beam excited at one point and corrected in another one by a piezoelectric actuator. This model allowed us to obtain several compensators, according to different control strategies. We then proceeded from an experimental point of view to study a device similar to our need from an actuating point of view and levels of magnitude (mechanical amplification, frequency range, etc.). ). The robust control strategies that we have developed to attenuate the vibratory displacements of this beam have led to conclusive results presented in the same chapter, first in simulation (which allowed us a comparative study), with and without the cutting process and then experimentally. The robustness of these control strategies was studied (in simulation) by adding uncertainties to the model in different ways. Then we have identified the model of the system, calculated the corresponding compensators and tested them on the test bench in order to validate the good functioning of the different control strategies used in this thesis. Finally, in order to use these strategies in rotating reference (active control tool holder), we have modeled and implemented the same steps for the case where the actuation is located in rotating reference and concerns two axes simultaneously, located in the XY plane of the tool holder. We first studied the transverse vibrations of a rotating beam in the general case before neglecting the inertia and gyroscopic phenomena. Actually, we are interested in the active control of milling, particularly in finishing applications, where long tools of small diameters are used. The new expressions of the two transfer functions of the system have been determined to obtain its state space representation, key of the active control. Projection of the cutting process on the rotating reference is essential to perform milling simulations with the active tool holder. This last chapter highlights the prospects of this thesis,that is the active control of the milling for all kinds of milling operations as well as for different tools with a mechatronic tool holder aimed for this kind of operation.
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Projeto robusto e análise de incertezas em dispositivos ressonantes para coleta de energia / Robust design and uncertainty analysis in resonant energy harvesting devicesMartins, Paulo Henrique 22 February 2018 (has links)
O estudo das vibrações é importante para prevenir danos em equipamentos ou mesmo evitar catástrofes de grande natureza. Nesse sentido, aproveitar a energia que seria dissipada na vibração e contribuir no controle do sistema representa um grande avanço tecnológico. O termo Energy Harvesting (Colheita de Energia) está relacionado ao contexto do aproveitamento energético, utilizando sistema de conversão para transformação da energia em eletricidade. Através de um dispositivo com viga engastada e massa inercial na extremidade, é possível realizar o estudo de vibração e coleta de energia, ao se considerar uma estrutura piezelétrica acoplada na viga e conectada a um circuito elétrico com resistor. Estruturas inteligentes que atuam na conversão de energia mecânica em elétrica, ou vice-versa, são fundamentais para esse estudo, o que motiva a inclusão dos sensores piezelétricos no projeto de dispositivos estudados e sujeitos a vibrações. Por outro lado, otimizar parâmetros de projeto é fundamental para aumentar a amplitude de vibração e tornar o processo com maior desempenho, tendo em vista maior captação de energia. Ainda, parâmetros otimizados podem estar sujeitos a incertezas do projeto e variações, devido a flutuações ambientais, como temperatura, pressão, propriedades dos materiais, geometria, etc. Por isso, técnicas robustas que tornem os projetos menos sensíveis a variações são interessantes para serem abordadas. Embora métodos de projetos robustos sejam eficientes, poucas pesquisas têm sido feitas na área da dinâmica de vibrações e alguns processos podem demandar tempo computacional dependendo do estudo ou projeto. Este trabalho tem como propósito abordar um método específico de projeto robusto focado em uma metodologia com matrizes chamadas ortogonais. Além disso, o método determinístico via algoritmo de Programação Sequencial Quadrático (SQP) é utilizado. O trabalho consiste numa abordagem para coleta de energia em um modelo de viga engastada, otimizando parâmetros e inserindo incertezas no sistema para análise de robustez e verificação de comprimentos adequados de vigas para os dispositivos. Os resultados mostram um aumento da energia coletada, analisando funções de resposta em frequências para saída de potência, diante de uma entrada de deslocamento no engaste do dispositivo, projetado via otimização determinística, além de aumento de robustez de acordo com certos critérios considerando circuito elétrico com resistência corretamente selecionada. / The study of vibrations is important to prevent damage to equipment or even prevent major catastrophes. In this sense harvesting the energy that would otherwise be dissipated in vibration and contributing to the control of the system represents a great technological advance. The term Energy Harvesting is related to the context of energy use, using a conversion system to transform energy into electricity. Through a device with clamped beam and inertial mass at the end, it is possible to study the vibration and energy harvesting, considering a piezoelectric structure coupled to the beam and connected to a resistance electric circuit. Smart structures that act in the conversion of mechanical energy to electrical energy, or vice versa, are fundamental for this study, which motivates the inclusion of piezoelectric sensors in the design of studied devices and subject to vibrations. On the other hand, optimizing design parameters is fundamental to increase the amplitude of vibration and increase process performance, in view of greater power uptake. Furthermore, optimized parameters may be subject to design uncertainties and variations due to environmental fluctuations such as temperature, pressure, material properties, geometry, etc. Therefore, robust techniques that make designs less sensitive to variations are interesting to be addressed. Although robust design methods are efficient, few researches have been done in the area of vibration dynamics and some processes may require computational time depending on the study or project. This work aims to address a specific method of robust design focused on a methodology with matrices called orthogonal. In addition, the deterministic method using Sequential Quadratic Programming (SQP) algorithm is used. The work consists of an approach to harvest energy in a clamped beam model, optimizing parameters and inserting uncertainties in the system for robustness analysis and verification of adequate beam lengths for the devices. The results show an increase in the harvested energy, analyzing frequency response functions for power output, in the face of a displacement input in the device clamp, designed through deterministic optimization,besides increasing robustness according to certain criteria considering electric circuit with correctly selected resistance.
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Robustez de concretos com baixo consumo de cimento Portland: desvios no proporcionamento e variabilidade granulométrica e morfológica dos agregados. / Robustness of concrete with low Portland cement consumption: deviations in proportioning and particle size and morphological variability of the aggregates.Rebmann, Markus Samuel 06 October 2016 (has links)
Concretos com baixo consumo de cimento Portland se justificam por motivos técnicos (menor calor de hidratação, retração e fissuração) e de sustentabilidade (menores consumos de energia e matérias-primas, emissão de CO2 e demanda por transporte). A variabilidade nas matérias-primas, nas condições ambientais e no processo de confecção de um concreto resultam em variabilidade de diversas propriedades no estado fresco e endurecido. A viabilidade da aplicação de concretos com baixo consumo de cimento, em escala no campo, depende da sensibilidade que estes apresentam diante das variabilidades presentes. Concretos com robustez adequada, ou seja, suficientemente tolerantes às variações, são desejáveis. Esta pesquisa teve como objetivo avaliar a robustez de concretos com baixo consumo de cimento, com foco principal em desvios no proporcionamento e variabilidade granulométrica e morfológica dos agregados. Aplicando conceitos de empacotamento e dispersão de partículas, uso de fílers calcários, escolha adequada dos materiais e aplicação de métodos reológicos para desenvolvimento da composição, desenvolveu-se um concreto com efetivo baixo consumo de ligantes (3,66 kg/m3/MPa). Os resultados obtidos indicam que as mudanças granulométricas são as mais impactantes, em especial devido à variabilidade no teor de pó fino nos agregados britados. Mudanças morfológicas, em especial na fração de tamanho que mais impacta no empacotamento (fração dominante), também são relevantes. O cenário de desvios de pesagem proporcionou o menor impacto dentre os três avaliados. Estas conclusões são específicas do concreto analisado e das particularidades dos cenários de variabilidade considerados. Por este motivo esta pesquisa buscou explicar de modo mais geral a influência das diversas variáveis. A distância que separa as partículas (IPS e MPT), a área específica dos materiais granulares e as concentrações de sólidos são alguns dos parâmetros que se correlacionam com o comportamento reológico nos diversos cenários avaliados. Com base no processo experimental e de análise dos resultados aplicados, propôs-se uma metodologia para avaliação de robustez e um índice numérico para avaliação quantitativa da robustez. Foram ainda propostas algumas ferramentas que visam atribuir mecanismos robustos ao processo de produção de concreto: sistema computacional para previsão de propriedades baseado em caracterização fundamental dos constituintes, uso de reômetro de concreto como instrumento de controle de qualidade e medida no campo da robustez e instrumentação de misturador como mecanismo de detecção de mudanças na etapa de mistura. / The use of concretes with low Portland cement content is justified by technical reasons (lower hydration heat, shrinkage and cracking) and sustainability (lower energy and raw materials consumptions, CO2 emissions and demand for transport). Variability in raw materials, environmental conditions and production process result in variability of various concrete properties in the fresh and hardened states. The feasibility of applying low cement concretes in large production scale depends on the sensitivity that these concretes show, given the existing variability. Concretes with adequate robustness, that is, sufficiently tolerant to variations are desirable. This research evaluated the robustness of concretes with low cement consumption, with focus on deviations in proportioning and particle size and morphological variability of the aggregates. Applying particle packing and dispersion concepts, rheological control, use of limestone fillers and appropriate of material choice a concrete with effective low binder consumption (3.66 kg/m3/MPa) was developed. The obtained results indicate that among the considered scenarios, the particle size changes are the most impactful, especially due to the presence of fine dust in the crushed aggregates. Morphological changes, especially in the size fraction that most impacts the packing (dominant fraction), are also relevant. Weighing deviations provided the smallest impact among the three evaluated scenarios. These findings, however, are specific to the analyzed concrete and the considered variability scenarios. For this reason, this research aimed to explain more generally the influence of several variables. The distance between the particles (IPS and MPT), the specific area of the granular material and the solids concentrations are some of the parameters that explain the rheological behavior. Based on the experimental process and the analysis of the applied results, a methodology was proposed for robustness evaluation and a numerical index for the quantitative evaluation of the robustness. Some additional tools to confer robust mechanisms to the concrete production process were proposed: a computer system for forecasting concrete properties, based on fundamental characterization of the constituents, use of a mobile rheometer as a quality control instrument and mixer instrumentation as change detection mechanism during the mixing process.
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Análise de robustez em redes complexas / Analysis of Robustness in Complex NetworksBarbieri, André Luiz 14 February 2011 (has links)
A teoria das redes complexas é uma área relativamente nova da Ciência, inspirada por dados empíricos tais como os obtidos de interações biológicas e sociais. Esta área apresenta uma natureza altamente interdisciplinar, de modo que tem unido cientistas de diferentes áreas, tais como matemática, física, biologia, ciência computação, sociologia, epidemiologia e muitas outras. Um dos problemas fundamentais nessa área é entender como a organização de redes complexas influencia em processos dinâmicos, como sincronização, propagação de epidemias e falhas e ataques. Nessa dissertação, é apresentada uma análise da relação entre estrutura e robustez de redes complexas através da remoção de vértices. Para a aplicação deste estudo, foram adquiridas bases de dados de interações de proteínas de quatro espécies, Saccharomyces cerevisiae, Caenorhabditis elegans, Drosophila melanogaster e Homo sapiens, como também mapas das malhas de rodovias de sete países, Brasil, Portugal, Polônia, Romênia, Austrália, Índia e África do Sul. Foi estudada a robustez dessas redes através de simulação de falhas e ataques, segundo uma dinâmica de remoção de vértices. Nesse caso, a variação na estrutura das redes devido a essa remoção foi quantificada pelas medidas do tamanho da maior componente conectado, do diâmetro e da média dos comprimentos dos menores caminhos. Ademais, foram utilizadas duas medidas para quantificar a robustez, isto é, a entropia da distribuição das conexões e entropia dinâmica, baseada em cadeias de Markov. Tais medidas foram aplicadas nas redes reais onde se verificou que as espécies mais complexas, como o homem e a mosca, apresentam as redes mais robustas. Com relação aos países, Romênia, Portugal e Brasil apresentam as malhas rodoviárias mais resistentes a perturbações. A correlação entre essas medidas de entropia e as medidas topológicas permitiu identificar que a média do grau dos vizinhos e o coeficiente da lei de potência da distribuição do número de conexões são as medidas que apresentam maior correlação com as medidas de entropia. Tal resultado sugere que a presença de conexões alternativas entre os vizinhos dos vértices removidos favorece a resiliência das redes, pois tendem a minimizar as perturbações causadas pelas remoções. No caso das malhas rodoviárias, foi proposta uma nova medida de acessibilidade e esta se mostrou altamente correlacionada com a entropia dinâmica. Nesse caso, verificou-se que as cidades localizadas no litoral e nas fronteiras dos países são as que menos contribuem para robustez das redes de rodovias. Desse modo, os resultados obtidos sugerem que o planejamento do sistema de transporte de um país deve priorizar o investimento em infra-estrutura rodoviária próximo das cidades com menor acessibilidade, de forma a torná-las mais acessíveis, visando melhorar o transporte de mercadorias e pessoas. Os métodos aqui propostos permitem identificar tais cidades. Ademais, na análise de redes de proteínas, os resultados obtidos podem auxiliar no desenvolvimento de novos modelos de redes, bem como entender os mecanismos evolutivos que priorizam a robustez dos organismos. / The study of complex networks is a relatively new area of science inspired by the empirical studies of real-world networks, such as social and biological networks. This are has a highly multidisciplinary nature, which has brought together researchers from many areas including mathematics, physics, biology, computer science, sociology, epidemiology, statistics and others. One of the main problems in this area is to know how the network organization is related to dynamic process, such as synchronization, epidemic spreading and topological perturbation due to deletion of nodes and edges. In this dissertation, it is presented a study of the relationship between the structure and resilience of complex networks. This investigation was applied to the protein-protein networks of four species, namely Saccharomyces cerevisiae, Caenorhabditis elegans, Drosophila melanogaster and Homo sapiens, as well as the road networks of seven countries, i.e. Brazil, Portugal, Romania, Australia, India, and South Africa. It was studied the resilience of such networks through simulations of random fails and attacks by node deletion. The topological changes due to this simulation were quantified by measures, including the size of the largest component, the diameter and the average shortest path length. In addition, the network robustness was quantified by the entropy of the degree distribution and the dynamic entropy, related to Markov chains. This analysis in real-world networks revealed that more complex species, such as the H. sapiens and D. melanogaster are the most resilient. In addition, Romania, Brazil and Portugal have the most robust road maps. The correlation analysis between topological and dynamic measures revealed that the average neighborhood degree and the coefficient of scaling in the power law of the degree distribution quantify the proprieties that most contribute for the resilience in protein networks. Moreover, with respect to the road networks, it was introduced a new accessibility measure, which revealed to be correlated to the dynamic entropy. In fact, cities localized in the border of networks are the ones with the smallest contribution for the network resilience. Therefore, the obtained results suggest that the traffic planning should mainly connect cities near the frontiers of countries, in order to improve the resilience and accessibility. In addition, the obtained results with respect to protein networks allow improving network modeling and understanding the biological processes that reinforce the resilience of organisms.
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