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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
41

[en] ACCELERATING BENDERS STOCHASTIC DECOMPOSITION FOR THE OPTIMIZATION OF PARTIAL BACKORDER CONTROL FOR PERIODIC REVIEW (R, S) INVENTORY SYSTEM WITH UNCERTAIN DEMAND / [pt] ACELERANDO A DECOMPOSIÇÃO DE BENDERS ESTOCÁSTICA PARA OTIMIZAÇÃO DE UM MODELO DE GESTÃO DE ESTOQUE DE REVISÃO PERIÓDICA (R, S) COM BACKORDER PARCIAL E DEMANDA INCERTA

FELIPE SILVA PLACIDO DOS SANTOS 05 September 2017 (has links)
[pt] Este trabalho apresenta uma proposta de aceleração da decomposição de Benders aplicada a uma versão mais geral e compacta (menos restrições e variáveis) do modelo de gestão de estoques, otimizado via programação estocástica de dois estágios que considera uma camada, um item, demanda incerta e política de controle (R, S). De maneira a ser possível considerar problemas de grande porte, foram aplicados os métodos L-Shaped tradicional com corte único e a sua forma estendida com múltiplos cortes. Resultados computacionais preliminares mostraram um substancial melhor desempenho computacional do método L-Shaped tradicional em relação à sua forma multi-cut L-Shaped, mesmo o primeiro necessitando de mais iterações para convergir na solução ótima. Tal observação motivou o desenvolvimento de uma nova técnica de aceleração da decomposição de Benders e de um conjunto de desigualdades válidas. Experimentos numéricos mostram que a abordagem proposta de combinar a técnica de aceleração elaborada com as desigualdades válidas desenvolvidas provê significativa redução do tempo computacional necessário para a solução de instâncias de grande porte. / [en] This dissertation presents a speed up proposal for the Benders decomposition applied to a more general and compact version (less constraints and variables) of inventory management model, optimized via two-stage stochastic programming, which considers one layer, one item, uncertain demand and control policy (R, S). In order to be possible to consider large scale problems, the L-Shaped traditional method with single cuts and its extended form with multiple cuts were applied. Preliminary computational results showed a substantially better computational performance of the traditional L-Shaped method in comparison to the multi-cut L-Shaped method, even with the first requiring more iterations to converge on optimum solutions. This observation led to the development of a new technique to accelerate the decomposition of Benders and a set of valid inequalities. Numerical experiments show that the proposed approach of combining the elaborate acceleration technique with the developed valid inequalities, provide significant reduction in the computational time required to solve large scale instances.
42

Design optimal des réseaux Fiber To The Home / Optimal design of Fiber To The Home networks

Angilella, Vincent 16 June 2018 (has links)
Pour les opérateurs, les réseaux FTTH représentent à la fois la solution de référence pour répondre à la demande croissante de trafic fixe, et un investissement considérable dû à leur mise en place. Le but de ces travaux est d'assurer le déploiement de réseaux de qualité à moindre coût. Nous commençons à présenter les différents aspects de la planification de ces réseaux qui en font un problème complexe. La littérature concernée est abordée afin d'exhiber les nouveaux défis que nous relevons. Puis nous élaborons des stratégies permettant de trouver la meilleure solution dans différents contextes. Plusieurs politiques de maintenance ou d'utilisation du génie civil sont ainsi explorées. Les problèmes rencontrés sont analysés à la lumière de divers outils d'optimisation (programmation entière, inégalités valides, programmation dynamique, approximations, complexités, inapproximabilité...) que nous utilisons et développons selon nos besoins. Les solutions proposées ont été testées et validées sur des instances réelles, et ont pour but d'être utilisées par Orange / For operators, FTTH networks are the most widespread solution to the increasing traffic demand. Their layout requires a huge investment. The aim of this work is to ensure a cost effective deployment of quality networks. We start by presenting aspects of this network design problem which make it a complex problem. The related literature is reviewed to highlight the novel issues that we solve. Then, we elaborate strategies to find the best solution in different contexts. Several policies regarding maintenance or civil engineering use will be investigated. The problems encountered are tackled using several combinatorial optimization tools (integer programming, valid inequalities, dynamic programming, approximations, complexity theory, inapproximability…) which will be developed according to our needs. The proposed solutions were tested and validated on real-life instances, and are meant to be implemented in a network planning tool from Orange
43

Conception sûre et optimale de systèmes dynamiques critiques auto-adaptatifs soumis à des événements redoutés probabilistes / Safe and optimal design of dynamical, critical self-adaptive systems subject to probabilistic undesirable events

Sprauel, Jonathan 19 February 2016 (has links)
Cette étude s’inscrit dans le domaine de l’intelligence artificielle, plus précisément au croisement des deux domaines que sont la planification autonome en environnement probabiliste et la vérification formelle probabiliste. Dans ce contexte, elle pose la question de la maîtrise de la complexité face à l’intégration de nouvelles technologies dans les systèmes critiques : comment garantir que l’ajout d’une intelligence à un système, sous la forme d’une autonomie, ne se fasse pas au détriment de la sécurité ? Pour répondre à cette problématique, cette étude a pour enjeu de développer un processus outillé, permettant de concevoir des systèmes auto-adaptatifs critiques, ce qui met en œuvre à la fois des méthodes de modélisation formelle des connaissances d’ingénierie, ainsi que des algorithmes de planification sûre et optimale des décisions du système. / This study takes place in the broad field of Artificial Intelligence, specifically at the intersection of two domains : Automated Planning and Formal Verification in probabilistic environment. In this context, it raises the question of the integration of new technologies in critical systems, and the complexity it entails : How to ensure that adding intelligence to a system, in the form of autonomy, is not done at the expense of safety ? To address this issue, this study aims to develop a tool-supported process for designing critical, self-adaptive systems. Throughout this document, innovations are therefore proposed in methods of formal modeling and in algorithms for safe and optimal planning.
44

New authentication mechanism using certificates for big data analytic tools

Velthuis, Paul January 2017 (has links)
Companies analyse large amounts of sensitive data on clusters of machines, using a framework such as Apache Hadoop to handle inter-process communication, and big data analytic tools such as Apache Spark and Apache Flink to analyse the growing amounts of data. Big data analytic tools are mainly tested on performance and reliability. Security and authentication have not been enough considered and they lack behind. The goal of this research is to improve the authentication and security for data analytic tools.Currently, the aforementioned big data analytic tools are using Kerberos for authentication. Kerberos has difficulties in providing multi factor authentication. Attacks on Kerberos can abuse the authentication. To improve the authentication, an analysis of the authentication in Hadoop and the data analytic tools is performed. The research describes the characteristics to gain an overview of the security of Hadoop and the data analytic tools. One characteristic is that the usage of the transport layer security (TLS) for the security of data transportation. TLS usually establishes connections with certificates. Recently, certificates with a short time to live can be automatically handed out.This thesis develops new authentication mechanism using certificates for data analytic tools on clusters of machines, providing advantages over Kerberos. To evaluate the possibility to replace Kerberos, the mechanism is implemented in Spark. As a result, the new implementation provides several improvements. The certificates used for authentication are made valid with a short time to live and are thus less vulnerable to abuse. Further, the authentication mechanism solves new requirements coming from businesses, such as providing multi-factor authenticationand scalability.In this research a new authentication mechanism is developed, implemented and evaluated, giving better data protection by providing improved authentication.
45

Specialized models for the long-term transmission network expansion planning problem /

Escobar Vargas, Laura Mónica January 2018 (has links)
Orientador: Rubén Augusto Romero Lázaro / Resumo: A análise de sistemas altamente complexos quando e analizado o problema de planejamento de expansão de redes de transmissão de longo prazo, é o foco principal deste trabalho. Os modelos e metodos propostos são aplicados ao problema de planejamento estático tradicional, que é um problema de otimização matemática classificado como NP-completo, não-linear inteiro misto. O qual envolve no investimento, variáveis operacionais contínuas e variáveis inteiras. O comportamento normal de cada sistema pode conter informação essencial para a criação de novos métodos, como os planos de corte baseados em cortes de diferença de ângulos para problemas de grande escala, o que é a base é o ponto de partida deste trabalho, derivando em desigualdades válidas é ciclos críticos. Os cortes angulares básicos reduzem o espaço de busca do problema e o tempo total de cálculo deste problema, enquanto ao método de inequações válidas que pode ser usado para fornecer limites inferiores sólidos no investimento ótimo do planejamento de transmissão, já que a diferença entre o modelo DC (modelo exato) e o modelo de transporte (modelo mais relaxado) são as restrições angulares. Os ciclos críticos têm sido desenvolvidos para melhoraralguns dos modelos tradicionais do problemas de planejamento da expansão da rede de transmissão de longo prazo. A razão por trás disso é a ausência da segunda lei de Kirchhoff, que completa a representação do sistema, mas aumenta a complexidade. Para resolver os problemas resultantes... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The analysis of highly complex systems when solving the long-term transmission network expansion planning problem is the main focus of this work. The proposed improved models and methodology are applied to the traditionalstatic planning problem, which is a mathematical optimization problem classified as NP-complete and mixed-integer nonlinear problem. It involves continuousoperating variables and integer investment variables. The normal behavior of each system can be shown essential information to the creation of new methods, as the cutting-planes based in bus-angle difference cuts for large-scale problems which were the starting point of this work, deriving in valid inequalities and critic cycles. The angular cuts aim to reduce the search space of the problem and the total computation time of this NP-hard problem as for the valid inequalities methodthat can be used to provide strong lower bounds on the optimal investment of the transmissionplanning, since the difference between the DC model (exact model) and the transport model (more relaxed model) are the angular constraints. Critic cycles has been develop in order to improve some of the traditional long-term transmission network expansion planning problem models. The reason behind it is the absence of second Kirchhoff’s law which completes the representationof the system, but increase the complexity. In order to solve the resulting problems, this work uses the modeling language AMPL with the solver CPLEX. In test systems w... (Complete abstract click electronic access below) / Doutor
46

Gregory research beliefs scale psychometric properties /

Gregory, Virgil L. January 2009 (has links)
Thesis (Ph.D.)--Indiana University, 2009. / Title from screen (viewed on August 27, 2009). School of Social Work, Indiana University-Purdue University Indianapolis (IUPUI). Advisor(s): Cathy Pike, Hea-Won Kim, Margaret Adamek, Drew Appleby. Includes vita. Includes bibliographical references (leaves 317-330).
47

Negativní jevy na ZŠ a současná legislativa / Negative influence on primary schools and legislative

HOMMER, Roman January 2016 (has links)
The diploma thesis deals with the theme of negative effects (forms of risk behaviour) at elementary schools pupils in Český Krumlov and mentions valid legilslation in the field of the risk behaviour primary prevention at school-compulsory choldren and youngsters. The theoretical part describes chosen socially-pathologic effects, the system of primary prevention and MŠMT legislation and other ministries as well in the field of risk behaviour prevention, as well as preventive aktivity of the institutions and organizations in the area of the city of Český Krumlov according to valid laws. The diploma thesis in the practical part includes empirical research performed at chosen elementary schools in Český Krumlov among teachers mapping their experience with the most frequent risk behaviour forms of pupils and further their knowledge and valid legislation usage inthe field of preventation both at schools and duringafter-school activities.
48

Flow-shop with time delays, linear modeling and exact solution approaches / Flow-shop avec temps de transport, modélisation linéaire et approches de résolution exacte

Mkadem, Mohamed Amine 07 December 2017 (has links)
Dans le cadre de cette thèse, nous traitons le problème de flow-shop à deux machines avec temps de transport où l’objectif consiste à minimiser le temps de complétion maximal. Dans un premier temps, nous nous sommes intéressés à la modélisation de ce problème. Nous avons proposé plusieurs programmes linéaires en nombres entiers. En particulier, nous avons introduit une formulation linéaire basée sur une généralisation non triviale du modèle d’affectation pour le cas où les durées des opérations sur une même machine sont identiques. Dans un deuxième temps, nous avons élargi la portée de ces formulations mathématiques pour développer plusieurs bornes inférieures et un algorithme exact basé sur la méthode de coupe et branchement (Branch-and-Cut). En effet, un ensemble d’inégalités valides a été considéré afin d’améliorer la relaxation linéaire de ces programmes et d’accélérer leur convergence. Ces inégalités sont basées sur la proposition de nouvelles règles de dominance et l’identification de sous-instances faciles à résoudre. L’identification de ces sous-instances revient à déterminer les cliques maximales dans un graphe d’intervalles. En plus des inégalités valides, la méthode exacte proposée inclut la considération d’une méthode heuristique et d’une procédure visant à élaguer les nœuds. Enfin, nous avons proposé un algorithme par séparation et évaluation (Branch-and-Bound) pour lequel, nous avons introduit des règles de dominance et une méthode heuristique basée sur la recherche locale. Nos expérimentations montrent l’efficacité de nos approches qui dominent celles de la littérature. Ces expérimentations ont été conduites sur plusieurs classes d’instances qui incluent celles de la littérature, ainsi que des nouvelles classes d’instances où les algorithmes de la littérature se sont montrés peu efficaces. / In this thesis, we study the two-machine flow-shop problem with time delays in order to minimize the makespan. First, we propose a set of Mixed Integer Programming (MIP) formulations for the problem. In particular, we introduce a new compact mathematical formulation for the case where operations are identical per machine. The proposed mathematical formulations are then used to develop lower bounds and a branch-and-cut method. A set of valid inequalities is proposed in order to improve the linear relaxation of the MIPs. These inequalities are based on proposing new dominance rules and computing optimal solutions of polynomial-time-solvable sub-instances. These sub-instances are extracted by computing all maximal cliques on a particular Interval graph. In addition to the valid inequalities, the branch-and-cut method includes the consideration of a heuristic method and a node pruning procedure. Finally, we propose a branch-and-bound method. For which, we introduce a local search-based heuristic and dominance rules. Experiments were conducted on a variety of classes of instances including both literature and new proposed ones. These experiments show the efficiency of our approaches that outperform the leading methods published in the research literature.
49

A High Performance Advanced Encryption Standard (AES) Encrypted On-Chip Bus Architecture for Internet-of-Things (IoT) System-on-Chips (SoC)

Yang, Xiaokun 25 March 2016 (has links)
With industry expectations of billions of Internet-connected things, commonly referred to as the IoT, we see a growing demand for high-performance on-chip bus architectures with the following attributes: small scale, low energy, high security, and highly configurable structures for integration, verification, and performance estimation. Our research thus mainly focuses on addressing these key problems and finding the balance among all these requirements that often work against each other. First of all, we proposed a low-cost and low-power System-on-Chips (SoCs) architecture (IBUS) that can frame data transfers differently. The IBUS protocol provides two novel transfer modes – the block and state modes, and is also backward compatible with the conventional linear mode. In order to evaluate the bus performance automatically and accurately, we also proposed an evaluation methodology based on the standard circuit design flow. Experimental results show that the IBUS based design uses the least hardware resource and reduces energy consumption to a half of an AMBA Advanced High-Performance Bus (AHB) and Advanced eXensible Interface (AXI). Additionally, the valid bandwidth of the IBUS based design is 2.3 and 1.6 times, respectively, compared with the AHB and AXI based implementations. As IoT advances, privacy and security issues become top tier concerns in addition to the high performance requirement of embedded chips. To leverage limited resources for tiny size chips and overhead cost for complex security mechanisms, we further proposed an advanced IBUS architecture to provide a structural support for the block-based AES algorithm. Our results show that the IBUS based AES-encrypted design costs less in terms of hardware resource and dynamic energy (60.2%), and achieves higher throughput (x1.6) compared with AXI. Effectively dealing with the automation in design and verification for mixed-signal integrated circuits is a critical problem, particularly when the bus architecture is new. Therefore, we further proposed a configurable and synthesizable IBUS design methodology. The flexible structure, together with bus wrappers, direct memory access (DMA), AES engine, memory controller, several mixed-signal verification intellectual properties (VIPs), and bus performance models (BPMs), forms the basic for integrated circuit design, allowing engineers to integrate application-specific modules and other peripherals to create complex SoCs.
50

Analýza vlivu polohy a technického stavu na obvyklou cenu vybraných rodinných domů ve Valašském Meziříčí a okolí / Analysis of the Location Impact and the Technical State on the Market Value of Selected Houses in and around Valašské Meziříčí

Horák, Vít January 2014 (has links)
This diploma thesis is describing extent of impact of location on real estate placed in town Valašské Meziříčí and comparing it with other real estates located near town Valašské Meziříčí. This diploma thesis is also solving question if is area of town Valašské Meziříčí so much significant that can balance better technical conditions or other positive technical distinctions of compared real estates. For solving this question will be evaluated five real estates. For the evaluations will be used these ways of evaluation: evaluation based on costs, comparing of real estates based on valid price regulation and direct comparing.

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