O problema de particionamento balanceado de grafos consiste em encontrar uma partição de tamanho k dos vértices de um grafo, minimizando o número de arestas que participam do corte tal que o tamanho de nenhuma parte exceda [en~k], para algum e e > [1, k). Essa dissertação estuda esse problema, apresentando uma revisão recente de heurísticas construtivas, heurísticas de refinamento e técnicas multinível. Também propomos um novo algoritmo híbrido para resolver esse problema de particionamento. Nós mostramos como diversas estratégias para construir e aprimorar partições, assim como algumas novas propostas, podem ser integradas para formar um GRASP com path-relinking. Reportamos experimentos computacionais que mostram que essa abordagem obtém soluções competitivas com particionadores no estado-da-arte. Em particular, o algoritmo híbrido é capaz de encontrar novos melhores valores conhecidos em algumas das menores instâncias, indicando que tem uma contribuição qualitativa comparado aos métodos existentes. / The balanced graph partitioning problem asks to find a k-partition of the vertex set of an undirected graph, which minimizes the total cut size and such that the size of no part exceeds en/k , for some ee > [1, k]. This dissertation studies this problem, providing a recent review of constructive heuristics, refinement heuristics and multilevel techniques. We also propose a new hybrid algorithm for solving this partitioning problem. We show how several good existing strategies for constructing and improving partitions, as well as some newly proposed ones, can be integrated to form a GRASP with path-relinking. We report computational experiments that show that this approach obtains solutions competitive with state-of-the-art partitioners. In particular, the hybrid algorithm is able to find new best known values in some of the smaller instances, indicating that it can make a qualitative contribution compared to existing methods.

Em uma cadeia produtiva de minério, as operações de pátio de estocagem, principalmente as de recuperação de pilhas de minério, exercem um papel fundamental por vincularem os processos de beneficiamento e de transporte. Com esta finalidade, esta dissertação propõe o sequenciamento das pilhas de minério a serem recuperadas através da adaptação de heurísticas trazidas pela literatura. Primeiramente, propõe-se uma heurística de sequenciamento para a retomada de pilhas de minério (entendidas como tarefas a serem sequenciadas) nos seus respectivos pátios através da aplicação de um índice de priorização de pilhas (IP). Tal índice apoia-se em fatores relevantes para as operações de pátios de estocagem, como capacidade das recuperadoras, qualidade e tempo de residência do minério e tempo de deslocamento entre pilhas (setup). A segunda heurística proposta, ATCSM (Apparent Tardiness Cost with Setups for mineral recovery), modifica a regra de despacho ATCS (Apparent Tardiness Cost with Setups) com vistas à sua aplicação na retomada de pilhas de minério em pátios de recuperação. O ATCSM apoia-se em fatores tidos como relevantes para as operações de pátios de estocagem, como tempo disponível para o empilhamento de um produto e data de entrega de uma pilha, entre outros. Os métodos propostos foram aplicados em um sistema de recuperação de minério composto por dois pátios, duas máquinas recuperadoras e doze pilhas. As sequências de recuperação geradas pelas heurísticas propostas foram consideradas coerentes por especialistas de pátio de estocagem de uma empresa mineradora. / In the supply chain of ore operations, stockyard operations, mainly the recovery of ore piles, play a fundamental role between beneficiation and transport processes. This thesis proposes new scheduling heuristics for sequencing ore piles recovering order. The first heuristics proposes a pile prioritization index (IP) that relies on relevant factors for stockyards operations, including machines capability, ore quality and residence time, and travel time between piles (setup). With similar purposes, the second heuristics modifies the dispatching rule ATCS (Apparent Tardiness Cost with Setups), yielding the ATCSM (Apparent Tardiness Cost with Setups for mineral recovery). The proposed ATCSM also relies on factors regarded as relevant to stockyard operations, as time available for stacking of a product and piles due date, among others. The proposed methods were applied to an ore recovery system composed of two stockyards, two recovery machines and twelve piles. The recovery sequences generated by both heuristics were considered consistent by experts from a mining company.

O problema de escalonamento num flow shop (ou flow shop scheduling problem, FSSP) é um modelo de sistemas de produção muito comum que é bem estudado na literatura. No entanto, quase toda a literatura foca-se em escalonamentos permutacionais, desconsiderando soluções ótimas e quase ótimas que são escalonamentos não-permutacionais. Além disso, a prática comum padroniza os tempos de processamento de cada operação, mesmo que estes tempos variem dependendo das diferentes capacidades dos operadores das máquinas, cuja diversidade deve ser considerada no processo de escalonamento quando seja significativa, e.g., em centros de emprego para deficientes (CEDs). Nesta tese, propomos métodos para resolver o FSSP não-permutacional, usando o mesmo tempo e esforço que os métodos do estado da arte usam para o FSSP permutacional, e produzindo escalonamentos não-permutacionais com melhor qualidade do que escalonamentos permutacionais e não-permutacionais produzidos por métodos do estado da arte. Também propomos métodos para resolver o problema combinado de designação de trabalhadores heterogêneos e escalonamento de tarefas num flow shop (ou heterogeneous workforce assignment and flow shop scheduling problem, Het-FSSP), produzindo soluções que compensam as diferentes capacidades e deficiências dos trabalhadores com pequenas perdas nos objetivos da produção. Além do mais, a designação de trabalhadores heterogêneos pode ser integrada em outros problemas de escalonamento, como fizemos com o problema combinado de designação de trabalhadores heterogêneos e escalonamento de tarefas num job shop (ou heterogeneous workforce assignment and job shop scheduling problem, Het-JSSP). / The flow shop scheduling problem (or FSSP) is a very common model of production systems that is well studied in the literature. However, almost all the literature focuses on the permutation FSSP, disregarding optimal and near optimal solutions that are non-permutation schedules. Besides, common practice standardizes the processing times of each operation, even when those times may vary depending on different capabilities of the machine operators, whose diversity must be considered in the scheduling process when it is significant, e.g., in Sheltered Work centers for Disabled (SWDs). In this thesis, we propose methods to solve the non-permutation FSSP, using the same time and effort as state-of-the-art methods for the permutation FSSP, and producing non-permutation schedules with better quality than permutation and non-permutation schedules produced by state-of-the-art methods. We also propose methods to solve the combined heterogeneous workforce assignment and flow shop scheduling problem (or Het-FSSP), producing solutions that compensate the different capabilities and disabilities of the workers with minor or null losses in the productivity objectives. Moreover, the heterogeneous workforce assignment may be integrated into other shop scheduling models, as we did with the heterogeneous workforce assignment and job shop scheduling problem (or Het-JSSP) with similar results.

O problema de escalonamento num flow shop (ou flow shop scheduling problem, FSSP) é um modelo de sistemas de produção muito comum que é bem estudado na literatura. No entanto, quase toda a literatura foca-se em escalonamentos permutacionais, desconsiderando soluções ótimas e quase ótimas que são escalonamentos não-permutacionais. Além disso, a prática comum padroniza os tempos de processamento de cada operação, mesmo que estes tempos variem dependendo das diferentes capacidades dos operadores das máquinas, cuja diversidade deve ser considerada no processo de escalonamento quando seja significativa, e.g., em centros de emprego para deficientes (CEDs). Nesta tese, propomos métodos para resolver o FSSP não-permutacional, usando o mesmo tempo e esforço que os métodos do estado da arte usam para o FSSP permutacional, e produzindo escalonamentos não-permutacionais com melhor qualidade do que escalonamentos permutacionais e não-permutacionais produzidos por métodos do estado da arte. Também propomos métodos para resolver o problema combinado de designação de trabalhadores heterogêneos e escalonamento de tarefas num flow shop (ou heterogeneous workforce assignment and flow shop scheduling problem, Het-FSSP), produzindo soluções que compensam as diferentes capacidades e deficiências dos trabalhadores com pequenas perdas nos objetivos da produção. Além do mais, a designação de trabalhadores heterogêneos pode ser integrada em outros problemas de escalonamento, como fizemos com o problema combinado de designação de trabalhadores heterogêneos e escalonamento de tarefas num job shop (ou heterogeneous workforce assignment and job shop scheduling problem, Het-JSSP). / The flow shop scheduling problem (or FSSP) is a very common model of production systems that is well studied in the literature. However, almost all the literature focuses on the permutation FSSP, disregarding optimal and near optimal solutions that are non-permutation schedules. Besides, common practice standardizes the processing times of each operation, even when those times may vary depending on different capabilities of the machine operators, whose diversity must be considered in the scheduling process when it is significant, e.g., in Sheltered Work centers for Disabled (SWDs). In this thesis, we propose methods to solve the non-permutation FSSP, using the same time and effort as state-of-the-art methods for the permutation FSSP, and producing non-permutation schedules with better quality than permutation and non-permutation schedules produced by state-of-the-art methods. We also propose methods to solve the combined heterogeneous workforce assignment and flow shop scheduling problem (or Het-FSSP), producing solutions that compensate the different capabilities and disabilities of the workers with minor or null losses in the productivity objectives. Moreover, the heterogeneous workforce assignment may be integrated into other shop scheduling models, as we did with the heterogeneous workforce assignment and job shop scheduling problem (or Het-JSSP) with similar results.

O problema de particionamento balanceado de grafos consiste em encontrar uma partição de tamanho k dos vértices de um grafo, minimizando o número de arestas que participam do corte tal que o tamanho de nenhuma parte exceda [en~k], para algum e e > [1, k). Essa dissertação estuda esse problema, apresentando uma revisão recente de heurísticas construtivas, heurísticas de refinamento e técnicas multinível. Também propomos um novo algoritmo híbrido para resolver esse problema de particionamento. Nós mostramos como diversas estratégias para construir e aprimorar partições, assim como algumas novas propostas, podem ser integradas para formar um GRASP com path-relinking. Reportamos experimentos computacionais que mostram que essa abordagem obtém soluções competitivas com particionadores no estado-da-arte. Em particular, o algoritmo híbrido é capaz de encontrar novos melhores valores conhecidos em algumas das menores instâncias, indicando que tem uma contribuição qualitativa comparado aos métodos existentes. / The balanced graph partitioning problem asks to find a k-partition of the vertex set of an undirected graph, which minimizes the total cut size and such that the size of no part exceeds en/k , for some ee > [1, k]. This dissertation studies this problem, providing a recent review of constructive heuristics, refinement heuristics and multilevel techniques. We also propose a new hybrid algorithm for solving this partitioning problem. We show how several good existing strategies for constructing and improving partitions, as well as some newly proposed ones, can be integrated to form a GRASP with path-relinking. We report computational experiments that show that this approach obtains solutions competitive with state-of-the-art partitioners. In particular, the hybrid algorithm is able to find new best known values in some of the smaller instances, indicating that it can make a qualitative contribution compared to existing methods.

Orientador: Fernando José Von Zuben / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Elétrica e de Computação / Made available in DSpace on 2018-08-16T05:45:11Z (GMT). No. of bitstreams: 1 Mello_AlanGodoySouza_M.pdf: 2308252 bytes, checksum: f9e7cf4b923ecf59d07a767543b8a7c4 (MD5) Previous issue date: 2010 / Resumo: Este trabalho propõe uma variante de otimização por enxame de partículas, na qual as influências entre as partículas são definidas através de uma rede complexa dinâmica. O objetivo principal é melhorar a capacidade de exploração do mecanismo de busca, particularmente junto a problemas multimodais. Com a vizinhança entre as partículas sendo definida de forma dinâmica e apresentando propriedades típicas de redes complexas, pretende-se: (i) promover uma rápida difusão de informação pela rede; (ii) viabilizar a formação de comunidades; e (iii) permitir que a influência das partículas ao longo da busca seja ajustável. Para validar o algoritmo proposto, foi feita uma análise sobre qual sua sensibilidade à variação de características da topologia. Em seguida, o seu desempenho foi comparado ao de outras propostas de otimização por enxame de partículas, presentes na literatura, utilizando para isso sete funções de teste com alta dimensionalidade e diferentes graus de dificuldade. Os resultados obtidos mostraram-se competitivos, indicando que topologias dinâmicas e complexas conduzem a mecanismos de busca eficazes e flexíveis, capazes de lidar com diferentes cenários de otimização / Abstract: This work proposes a variant of particle swarm optimization, in which the influences among particles are defined by a dynamic complex network. The main purpose of this work is to improve the exploration capability of the search mechanism, particularly in multimodal problems. With the neighborhood of the particles being defined in a dynamic way and presenting typical properties of complex networks, the intention is: (i) to promote a rapid diffusion of information throughout the network; (ii) to enable the formation of communities; and (iii) to allow an adjustable influence of the particles along the search. To validate the proposed algorithm, an analysis of its sensitivity to alternative characteristics of the topology was performed. Further, its performance was compared to other particle swarm optimization proposals, available in the literature, on seven high-dimensional benchmark functions presenting distinct difficulty levels. The obtained results were competitive, indicating that dynamic complex topologies guide to effective and flexible search mechanisms, capable of dealing with distinct optimization scenarios / Mestrado / Engenharia de Computação / Mestre em Engenharia Elétrica

Le Cloud est devenu une plate-forme très répandue pour le déploiement d'applications distribuées. Beaucoup d'entreprises peuvent sous-traiter leurs infrastructures d'hébergement et, ainsi, éviter des dépenses provenant d'investissements initiaux en infrastructure et de maintenance.Des petites et moyennes entreprises, en particulier, attirés par le modèle de coûts sur demande du Cloud, ont désormais accès à des fonctionnalités comme le passage à l'échelle, la disponibilité et la fiabilité, qui avant le Cloud étaient presque réservées à de grandes entreprises.Les services du Cloud peuvent être offerts aux utilisateurs de plusieurs façons. Dans cette thèse, nous nous concentrons sur le modèle d'Infrastructure sous Forme de Service. Ce modèle permet aux utilisateurs d’accéder à des ressources de calcul virtualisés sous forme de machine virtuelles (MVs).Pour installer une application distribuée, un client du Cloud doit d'abord définir l'association entre son application et l'infrastructure. Il est nécessaire de prendre en considération des contraintesde coût, de ressource et de communication pour pouvoir choisir un ensemble de MVs provenant d'opérateurs de Cloud publiques et privés le plus adaptés. Cependant, étant donné la quantité exponentiel de configurations, la définition manuelle de l'association entre application et infrastructure peut être un challenge dans des scénarios à large échelle ou ayant des contraintes importantes de temps. En effet, ce problème est une généralisation du problème de calcul de homomorphisme de graphes, qui est NP-complet.Dans cette thèse, nous adressons le problème de calculer des placements initiaux et de reconfiguration pour des applications distribuées sur potentiellement de multiples Clouds. L'objectif est de minimiser les coûts de location et de migration en satisfaisant des contraintes de ressources et communications. Pour cela, nous proposons des heuristiques performantes capables de calculer des placements de bonne qualité très rapidement pour des scénarios à petite et large échelles. Ces heuristiques, qui sont basées sur des algorithmes de partition de graphes et de vector packing, ont été évaluées en les comparant avec des approches de l'état de l'art comme des solveurs exactes et des méta-heuristiques. Nous montrons en utilisant des simulations que les heuristiques proposées arrivent à calculer des solutions de bonne qualité en quelques secondes tandis que des autres approches prennent des heures ou jours pour les calculer. / The Cloud has become a very popular platform for deploying distributed applications. Today, virtually any credit card holder can have access to Cloud services. There are many different ways of offering Cloud services to customers. In this thesis we especially focus on theInfrastructure as a Service (IaaS), a model that, usually, proposes virtualized computing resources to costumers in the form of virtual machines (VMs). Thanks to its attractive pay-as-you-use cost model, it is easier for customers, specially small and medium companies, to outsource hosting infrastructures and benefit of savings related to upfront investments and maintenance costs. Also, customers can have access to features such as scalability, availability, and reliability, which previously were almost exclusive for large companies. To deploy a distributed application, a Cloud customer must first consider the mapping between her application (or its parts) to the target infrastructure. She needs to take into consideration cost, resource, and communication constraints to select the most suitable set of VMs, from private and public Cloud providers. However, defining a mapping manually may be a challenge in large-scale or time constrained scenarios since the number of possible configuration explodes. Furthermore, when automating this process, scalability issues must be taken into account given that this mapping problem is a generalization of the graph homomorphism problem, which is NP-complete.In this thesis we address the problem of calculating initial and reconfiguration placements for distributed applications over possibly multiple Clouds. Our objective is to minimize renting and migration costs while satisfying applications' resource and communication constraints. We concentrate on the mapping between applications and Cloud infrastructure. Using an incremental approach, we split the problem into three different parts and propose efficient heuristics that can compute good quality placements very quickly for small and large scenarios. These heuristics are based on graph partition and vector packing heuristics and have been extensively evaluated against state of the art approaches such as MIP solvers and meta-heuristics. We show through simulations that the proposed heuristics manage to compute solutions in a few seconds that would take many hours or days for other approaches to compute.

The use of examples is known to be important in learning, they should be “exemplary” and function as role-models. Teaching and learning problem solving and programming in the object oriented paradigm is recognised as difficult. Object orientation is designed to handle complexity and large systems, and not with education in focus. The fact that object orientation often is used as first paradigm makes the design of examples even more difficult and important. In this thesis, a survey of the literature is made to establish a set of characteristics for object orientation in general. This set of characteristics is then applied to the educational setting of introducing novices to object oriented problem solving and programming, resulting in a number of heuristics for educational purposes, called He[d]uristics. The proposed He[d]uristics are targeted towards educators designing small-scale examples for novices, and is an attempt to provide help in designing suitable examples, not a catalogue of good ones. The He[d]uristics are discussed and exemplified and also evaluated versus the derived set of characteristics and known common problems experienced by novices.

Optimisation heuristics rely on implicit or explicit assumptions about the structure of the black-box fitness function they optimise. A review of the literature shows that understanding of structure and linkage is helpful to the design and analysis of heuristics. The aim of this thesis is to investigate the role that problem structure plays in heuristic optimisation. Many heuristics use ordinal operators; which are those that are invariant under monotonic transformations of the fitness function. In this thesis we develop a classification of pseudo-Boolean functions based on rank-invariance. This approach classifies functions which are monotonic transformations of one another as equivalent, and so partitions an infinite set of functions into a finite set of classes. Reasoning about heuristics composed of ordinal operators is, by construction, invariant over these classes. We perform a complete analysis of 2-bit and 3-bit pseudo-Boolean functions. We use Walsh analysis to define concepts of necessary, unnecessary, and conditionally necessary interactions, and of Walsh families. This helps to make precise some existing ideas in the literature such as benign interactions. Many algorithms are invariant under the classes we define, which allows us to examine the difficulty of pseudo-Boolean functions in terms of function classes. We analyse a range of ordinal selection operators for an EDA. Using a concept of directed ordinal linkage, we define precedence networks and precedence profiles to represent key algorithmic steps and their interdependency in terms of problem structure. The precedence profiles provide a measure of problem difficulty. This corresponds to problem difficulty and algorithmic steps for optimisation. This work develops insight into the relationship between function structure and problem difficulty for optimisation, which may be used to direct the development of novel algorithms. Concepts of structure are also used to construct easy and hard problems for a hill-climber.

Today, web, Internet, mobile and other ambient technologies engage in persuasive interaction with people. The technology designed to reinforce and change user’s attitude or behaviors or both through persuasion and social influence are persuasive technologies. Recently, persuasive systems and services are becoming increasingly abundant and ubiquitous. Evaluation of these systems is a challenging endeavor and typically requires a simple and efficient method. Nielsen suggests heuristic evaluation as a method for intuitive, inexpensive and easy evaluation of a user interface design. The purpose of this thesis is to examine heuristic evaluation as a method to evaluate the persuasive potential of software programs. The Heuristics used were operationalized version of Fogg’s persuasive design principles. Software programs MS Word, MS PowerPoint, Counter-Strike, The Sims, Stone and Plan Eat Smile were chosen with the goal of measuring their ability to change behavior or attitude of users. The Evaluation was performed on the software programs using three evaluators and the test results indicated that they possess significant persuasive potential. It was concluded that the set of heuristics which were developed can be used to perform summative heuristic evaluation and the method used was helpful in evaluating the persuasive potential of software programs.