Submitted by Franciele Moreira (francielemoreyra@gmail.com) on 2018-04-17T15:48:39Z No. of bitstreams: 2 Tese - Joelma de Moura Ferreira - 2018.pdf: 58164875 bytes, checksum: c19d300de77be476834ac9c2e7ca8b0e (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2018-04-18T11:17:22Z (GMT) No. of bitstreams: 2 Tese - Joelma de Moura Ferreira - 2018.pdf: 58164875 bytes, checksum: c19d300de77be476834ac9c2e7ca8b0e (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2018-04-18T11:17:22Z (GMT). No. of bitstreams: 2 Tese - Joelma de Moura Ferreira - 2018.pdf: 58164875 bytes, checksum: c19d300de77be476834ac9c2e7ca8b0e (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2018-03-21 / Edge bundling is a technique to group, align, coordinate and position the depiction of edges in a graph drawing, so that sets of edges appear to be brought together into shared visual structures, i.e. bundles. The ultimate goal is to reduce clutter to improve how it conveys information. This thesis provides a general formulation for the explicity edge bundling problems, as a formal combinatorial optimization problem. This allows for the definition and comparison of edge bundling problems. In addition, we present four explicity edge bundling optimization problems that address minimizing the total number of bundles, in conjunction with other aspects, as the main goal. An evolutionary edge bundling algorithm is described. The algorithm was successfully tested by solving three related problems applied to real-world instances. The reported experimental results demonstrate the effectiveness and the applicability of the proposed evolutionary algorithm to help resolve edge bundling problems formally defined as optimization models. / A união de arestas em feixes é uma técnica para agrupar, alinhar, coordenar e posicionar a representação de arestas em um desenho de grafo, de modo que os conjuntos de arestas pareçam ser reunidos em estruturas visuais compartilhadas, ou seja, feixes. O objetivo final é reduzir a poluição visual do desenho melhorando a forma como ele transmite informações. Esta tese apresenta uma formulação geral para problemas de união explícita de arestas, como um problema formal de otimização. Essa formulação pode ser usada para definir e comparar problemas de união de arestas. Ainda, são definidos quatro problemas de otimização de união explícita de arestas, que têm por objetivo minimizar o número total de feixes, em conjunto com outros aspectos. Um algoritmo evolucionário é descrito. O algoritmo foi testado com sucesso em três dos problemas relacionados aplicados a instâncias do mundo real. Os resultados experimentais demonstram a eficácia e a aplicabilidade do algoritmo evolutivo proposto para ajudar a resolver problemas de união de arestas em feixes formalmente definidos como um modelo de otimização.

Submitted by Luciana Ferreira (lucgeral@gmail.com) on 2017-08-03T11:05:17Z No. of bitstreams: 2 Dissertação - Carlos Alexandre Xavier da Silva - 2017.pdf: 2190162 bytes, checksum: 7c5e13d2301a93a75a0e2d68e1b9a893 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2017-08-03T11:06:02Z (GMT) No. of bitstreams: 2 Dissertação - Carlos Alexandre Xavier da Silva - 2017.pdf: 2190162 bytes, checksum: 7c5e13d2301a93a75a0e2d68e1b9a893 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2017-08-03T11:06:02Z (GMT). No. of bitstreams: 2 Dissertação - Carlos Alexandre Xavier da Silva - 2017.pdf: 2190162 bytes, checksum: 7c5e13d2301a93a75a0e2d68e1b9a893 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2017-06-26 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / In one version of the Simple Assembly Line Balancing Problem (SALBP) tasks are assigned to stations along an assembly line with a fixed cycle time in order to minimise the required number of stations. It is assumed that the total work needed for each product unit has been partitioned into economically indivisible tasks. In practice, it may be that the minimal number of stations can be reduced when it is possible to further divide particular tasks in limited ways even with additional time penalty costs. Allowing task division leads to a new assembly line balancing problem, TDALBP (Task Division Assembly Line Balancing Problem) and a solution procedure for it. This work introduces a mathematical model for the TDALBP and presents promising computational results for the adaptation of some classical SALBP instances from the research literature. The results demonstrate that the TDALBP has the potential to significantly improve assembly line performance. / O balanceamento eficaz de uma linha de produção é importante para aprimorar a produtividade e reduzir custos de uma industria. O problema do balanceamento de linhas de produção (Assembly Line Balancing Problem - ALBP) envolve atribuir as tarefas necessárias para produzir cada unidade de um produto entre estações de trabalho ao longo de uma linha de produção, a fim de otimizar alguma medida de desempenho do sistema. Tradicionalmente, supõe-se que o trabalho total necessário para cada unidade de produto foi particionado em tarefas economicamente indivisíveis, de modo que uma maior divisão gera custos desnecessários. Assim, cada tarefa requerida não pode ser dividida e deve ser realizada em uma única estação. Na prática, no entanto, isso pode não ser sempre verdadeiro quando existe um objetivo orientado ao tempo, tal como a minimização do número de estações para um determinado tempo de ciclo. Neste caso, pode ser que o número mínimo das estações possa ser reduzido quando for possível continuar a dividir tarefas particulares de formas limitadas, mesmo se a divisão induzir custos adicionais de tempo. A permissão de tal divisão de tarefas nos leva a um novo problema de balanceamento de linhas de produção, o qual denotamos por TDALBP (Task Division Assembly Line Balancing Problem). Nós propomos um modelo de programação linear inteira binária para o TDALBP e procedimentos efetivos para solucioná-lo. Os procedimentos foram avaliados sobre adaptações de várias instâncias SALBP clássicas da literatura. Os resultados computacionais são promissores e mostram o potencial do TDALBP para a melhora significativa do desempenho de linhas de produção.

O problema de dimensionamento de lotes, objeto desse estudo, considera um ambiente composto por múltiplas plantas independentes, múltiplos itens e múltiplos períodos. O ambiente de produção tem capacidade limitada e as plantas podem produzir os mesmos itens. Cada planta tem uma demanda própria e é permitida a transferência de lotes entre as plantas, o que envolve um certo custo. Este problema tem como caso particular o de dimensionamento de lotes com máquinas paralelas. O objetivo desta dissertação é propor uma heurística baseada na meta-heurística GRASP (Greedy Randomized Adaptive Search Procedures). Além disso, uma estratégia path relinking foi incorporada ao GRASP como uma fase de melhoria do algoritmo. Para verificar a eficiência da heurística proposta, os seus resultados são comparados aos da literatura tanto no caso de máquinas paralelas quanto no de múltiplas plantas. Como resultado, o problema de múltiplas plantas obteve melhores resultados quando comparado aos da heurística da literatura. Com relação ao problema de máquinas paralelas, a heurística proposta se mostrou competitiva / The lot sizing problem, which is the aim of this study, considers an environment consisting of multiple independent plants, multiple items and multiple periods. The production environment has limited capacity and the plants can produce the same items. Each plant has its own demand and the lot transfers between the plants are permitted, which involves a certain cost. This problem has as a particular case the parallel machines lot sizing problem. The objective of this dissertation is to propose a heuristic based on the GRASP (Greedy Randomized Adaptive Search Procedures). Furthermore, a path relinking phase is embedded in the GRASP to obtain better performance. To verify the efficiency of the proposed heuristic, its results were compared with the literature as for the multi-plant as for parallel machines problem. Computational tests showed that the proposed heuristic performed better than other literature heuristic concerning the multiplant problem. Concerning the parallel machines, the heuristic is competitive

The decline of Moore's law has catalyzed a significant effort to identify beyond-CMOS devices and architectures for the coming decades. A multitude of classical and quantum systems have been proposed to address this challenge, and spintronics has emerged as a promising approach for these post-Moore systems. Many of these architectures are tailored specifically for applications in combinatorial optimization and machine learning. Here we propose the use of spintronics for such applications by exploring two distinct but related computing paradigms. First, the use of spin-currents to manipulate and control quantum information is investigated with demonstrated high-fidelity gate operation. This control is accomplished through repeated entanglement and measurement of a stationary qubit with a flying-spin through spin-torque like effects. Secondly, by transitioning from single-spin quantum bits to larger spin ensembles, we then explore the use of stochastic nanomagnets to realize a probabilistic system that is intrinsically governed by Boltzmann statistics. The nanomagnets explore the search space at rapid speeds and can be used in a wide-range of applications including optimization and quantum emulation by encoding the solution to a given problem as the ground state of the equivalent Boltzmann machine. These applications are demonstrated through hardware emulation using an all-digital autonomous probabilistic circuit.

The study of networks has seen a tremendous breed of researches due to the explosive spectrum of practical problems that involve networks as the access point. Those problems widely range from detecting functionally correlated proteins in biology to finding people to give discounts and gain maximum popularity of a product in economics. Thus, understanding and further being able to manipulate/control the development and evolution of the networks become critical tasks for network scientists. Despite the vast research effort putting towards these studies, the present state-of-the-arts largely either lack of high quality solutions or require excessive amount of time in real-world `Big Data' requirement. This research aims at affirmatively boosting the modern algorithmic efficiency to approach practical requirements. That is developing a ground-breaking class of algorithms that provide simultaneously both provably good solution qualities and low time and space complexities. Specifically, I target the important yet challenging problems in the three main areas: Information Diffusion: Analyzing and maximizing the influence in networks and extending results for different variations of the problems. Community Detection: Finding communities from multiple sources of information. Security and Privacy: Assessing organization vulnerability under targeted-cyber attacks via social networks.

[pt] Desde a sua origem, as abordagens a problemas de Otimização Combinatória polarizam-se entre métodos exatos e heurísticos. Recentemente, porém, estratégias que combinam ambos os métodos têm sido propostas para os mais variados problemas, apresentando resultados promissores. Nesse contexto, destacam-se os conceitos de vizinhaças de bola e elipsoidal, que realizam buscas em relação a uma ou mais soluções de referência. Este trabalho estuda a aplicação de tais vizinhanças para o Problema de Roteamento de Veículos com Restrição de Capacidade (CVRP), sobre o algoritmo de Branch-and-Cut-and-Price Robusto. Experimentos foram realizados e seus resultados analisados. / [en] Since its inception, approaches to Combinatorial Optimization were polarized between exact and heuristic methods. Recently, however, strategies that combine both methods have been proposed for various problems, showing promising results. In this context, the concepts of ball and ellipsoidal neighborhood appear, which perform a search regarding one or more reference solutions. This work studies the application of such neighborhoods for the Capacitated Vehicle Routing Problem (CVRP), using the Robust Branchand- Cut-and-Price algorithm. Experiments were made and its results were analyzed.

<p>Games on graphs have become an indispensable tool in modern computer science. They provide powerful and expressive models for numerous phenomena and are extensively used in computer- aided verification, automata theory, logic, complexity theory, computational biology, etc.</p><p>The infinite games on finite graphs we study in this thesis have their primary applications in verification, but are also of fundamental importance from the complexity-theoretic point of view. They include parity, mean payoff, and simple stochastic games.</p><p>We focus on solving graph games by using iterative strategy improvement and methods from linear programming and combinatorial optimization. To this end we consider old strategy evaluation functions, construct new ones, and show how all of them, due to their structural similarities, fit into a unifying combinatorial framework. This allows us to employ randomized optimization methods from combinatorial linear programming to solve the games in expected subexponential time.</p><p>We introduce and study the concept of a controlled optimization problem, capturing the essential features of many graph games, and provide sufficent conditions for solvability of such problems in expected subexponential time.</p><p>The discrete strategy evaluation function for mean payoff games we derive from the new controlled longest-shortest path problem, leads to improvement algorithms that are considerably more efficient than the previously known ones, and also improves the efficiency of algorithms for parity games.</p><p>We also define the controlled linear programming problem, and show how the games are translated into this setting. Subclasses of the problem, more general than the games considered, are shown to belong to NP intersection coNP, or even to be solvable by subexponential algorithms.</p><p>Finally, we take the first steps in investigating the fixed-parameter complexity of parity, Rabin, Streett, and Muller games.</p>

No description available.

Nos travaux portent sur la modelisation et la resolution de problemes d'optimisation combinatoire emergeant dans le cadre de la planification de missions spatiales. Ces problemes de grande taille presentent des caracteristiques communes en termes de types de donnees, de contraintes et de criteres a optimiser. Nous nous focalisons sur l'apport de la programmation lineaire pour ces problemes, associee a des methodes de simplification de l'espace de recherche, par decomposition ou grace a des techniques de propagation de contraintes. Nous avons plus particulierement etudie deux problemes. Le premier concerne la planification de communications sonde/satellite et d'experiences dans un projet d'exploration martienne. Une decomposition de ce probleme permet de le formuler comme deux problemes independants : un probleme de planification des communications que nous modelisons et resolvons par programmation lineaire en nombres entiers, et un probleme d'aide a la decision pour la planification des experiences, pour lequel nous etablissons des courbes d'evaluation de la charge des ressources deduites de l'application de techniques de propagation de contraintes basees sur un raisonnement energetique. Le second probleme etudie est celui de la planification de prises de vue d'un satellite d'observation de la Terre. Nous proposons un modele lineaire en variables mixtes et nous developpons une approche de resolution par generation de colonnes, qui est une adaptation de la programmation lineaire au traitement de problemes de grande taille, faisant appel a certaines techniques de decomposition des modeles.

The rapid developments in the field of DNA computing reflects two substantial questions: 1. Which models for DNA based computation are really universal? 2. Which model fulfills the requirements to a universal lab-practicable programmable DNA computer that is based on one of these models? This paper introduces the functional model DNA-HASKELL focussing its lab-practicability. This aim could be reached by specifying the DNA based operations in accordiance to an analysis of molecular biological processes. The specification is determined by an abstraction level that includes nucleotides and strand end labels like 5'-phosphate. Our model is able to describe DNA algorithms for any NP-complete problem - here exemplified by the knapsacik problem - as well as it is able to simulate some established mathematical models for computation. We point out the splicing operation as an example. The computational completeness of DNA-HASKELL can be supposed. This paper is based on discussions about the potenzial and limits of DNA computing, in particular the practicability of a universal DNA computer.