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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.
11

Reconciliation of a Rayleigh-Ritz beam model with experimental data

Lindholm, Brian Eric 10 June 2009 (has links)
In order to perform structural optimization and/or modification on a structure, an analytical model which sufficiently describes the behavior of the structure must be developed. Analytical models can be generated for almost any structure, but such a model will generally not effectively predict the behavior of the structure unless the model is somehow reconciled with experimental data taken from the structure. Additionally, the model must also be complete, i.e., it must not only model the structure but also model any suspension system used to support the structure. If the suspension is not included in the model, any attempt to reconcile the model with experimental data will result in a incorrect model. Using this incorrect model to perform structural modification cannot be expected to give correct results. In this thesis, an approach for estimating the effects of a suspension system on the flexural vibration of a structure is developed. These effects are treated mathematically as variations in boundary conditions. Topics discussed include formulation of an analytical model that includes suspension effects, experimental methods for acquiring mode shapes which exhibit these effects, and reconciliation techniques for matching analytical mode shapes to experimental mode shapes to determine the effective boundary conditions. / Master of Science
12

Vers une optimisation de la chaine logistique : proposition de modèles conceptuels basés sur le PLM (Product Lifecycle Management) / Towards supply chain optimization : proposition of conceptual models based on PLM (Product Lifecycle Management)

Bouhaddou, Imane 27 February 2015 (has links)
Consciente que l’unité de compétitivité n’est plus l’entreprise mais toute la chaîne logistique contribuant à la réalisation du produit, les efforts consentis par l’entreprise se matérialisent, d’une part, par la volonté de maîtriser au mieux les activités de conception des produits et d’autre part, par la construction de collaborations entre tous les acteurs de la chaîne logistique participant au cycle de vie du produit. Cela a conduit à l’émergence d’une gestion collaborative du cycle de vie du produit appelée communément PLM. L’objet de cette thèse consiste à définir une démarche méthodologique pour répondre à la problématique suivante : Comment le PLM pourra t-il participer à l’optimisation de la chaîne logistique ? Nous adoptons, dans cette thèse, une approche hybride combinant PLM et modèles mathématiques pour optimiser les décisions de conception simultanée du produit et de sa chaîne logistique. Nous proposons des modèles conceptuels pour résoudre de manière formelle le compromis entre PLM et modèles mathématiques pour une optimisation de la chaîne logistique. Contrairement aux approches classiques centralisées utilisées pour traiter le problème intégré de conception du produit et de sa chaîne logistique et qui engendrent des modèles mathématiques compliqués, nous adoptons une démarche couplant des décisions centralisées quand il s’agit d’intégrer les contraintes des différents maillons de la chaîne logistique et une approche décentralisée quand il s’agit d’optimiser localement chaque maillon de la chaîne. Le mode décentralisé réduit la complexité de résolution des modèles mathématiques et permet à la chaîne logistique de répondre rapidement à l’évolution des conditions locales de chaque maillon. Le PLM joue le rôle d’intégrateur. En effet, le regroupement centralisé des informations par le PLM permet de prendre en considération la dépendance entre les maillons améliorant ainsi les résultats obtenus par optimisation locale. / AIt is recognized that competition is shifting from “firm versus firm” perspective to “supply chain versus supply chain” perspective. Therefore, the ability to optimize the supply chain is becoming the critical issue for companies to win the competitive advantage. Furthermore, all members of a given supply chain must work together to respond to the changes of market demand rapidly. In the actual context, enterprises not only must enhance their relationships with each others, but also need to integrate their business processes through product life cycle activities. This has led to the emergence of a collaborative product lifecycle management commonly known as PLM. The objective of this thesis is to define a methodological approach which answers to the following problematic: How can PLM contribute to supply chain optimization ? We adopt, in this thesis, a hybrid approach combining PLM and mathematical models to optimize decisions for simultaneous design of the product and its supply chain. We propose conceptual models to solve formally the compromise between PLM and mathematical models for supply chain optimization. Unlike traditional centralized approaches used to treat the problem of integrated design of the product and its supply chain which generate complex mathematical models, we adopt an approach combining centralized decisions while integrating the constraints of the different supply chain partners during the product design and decentralized decisions when it comes to locally optimize each supply chain partner. The decentralized approach reduces the complexity of solving mathematical models and allows the supply chain to respond quickly to the evolution of local conditions of each partner. PLM will assure the integration of the different supply chain partners. Indeed, the information centralization by the PLM enables to take into consideration the dependence between these partners, improving therefore local optimization results.
13

Řízení zásobní funkce nádrže s využitím metod umělé inteligence / Management of water reservoir storage function using methods of artificial intelligence

Urbanec, Patrik January 2020 (has links)
The subject of this thesis is to control the storage function of the reservoir using artificial intelligence methods, including the construction of the appropriate control algorithm. The thesis is divided into the theoretical part and the part of the application of reservoir storage function control. The theoretical part describes the control algorithm and the prediction model. The following are basic optimization methods and artificial intelligence methods. The second part presents the historical data used for the prediction model. The following is a description of calibration and validation of the control module and evaluation of the application results. Finally, there is a comparison and summary of individual results, control algorithm and prediction model. According to the results, the control algorithm can be recommended for further investigation.
14

Efficient and robust aircraft landing trajectory optimization

Zhao, Yiming 18 January 2012 (has links)
This thesis addresses the challenges in the efficient and robust generation and optimization of three-dimensional landing trajectories for fixed-wing aircraft subject to prescribed boundary conditions and constraints on maneuverability and collision avoidance. In particular, this thesis focuses on the airliner emergency landing scenario and the minimization of landing time. The main contribution of the thesis is two-fold. First, it provides a hierarchical scheme for integrating the complementary strength of a variety of methods in path planning and trajectory optimization for the improvement in efficiency and robustness of the overall landing trajectory optimization algorithm. The second contribution is the development of new techniques and results in mesh refinement for numerical optimal control, optimal path tracking, and smooth path generation, which are all integrated in a hierarchical scheme and applied to the landing trajectory optimization problem. A density function based grid generation method is developed for the mesh refinement process during numerical optimal control. A numerical algorithm is developed based on this technique for solving general optimal control problems, and is used for optimizing aircraft landing trajectories. A path smoothing technique is proposed for recovering feasibility of the path and improving the tracking performance by modifying the path geometry. The optimal aircraft path tracking problem is studied and analytical results are presented for both the minimum-time, and minimum-energy tracking with fixed time of arrival. The path smoothing and optimal path tracking methods work together with the geometric path planner to provide a set of feasible initial guess to the numerical optimal control algorithm. The trajectory optimization algorithm in this thesis was tested by simulation experiments using flight data from two previous airliner accidents under emergency landing scenarios.The real-time application of the landing trajectory optimization algorithm as part of the aircraft on-board automation avionics system has the potential to provide effective guidelines to the pilots for improving the fuel consumption during normal landing process, and help enhancing flight safety under emergency landing scenarios. The proposed algorithms can also help design optimal take-off and landing trajectories and procedures for airports.
15

Optimalizace investičních strategií pomocí genetických algoritmů / Optimization of Investment Strategy Using Genetic Algorithms

Novák, Tomáš January 2015 (has links)
This thesis is focused on the design and optimization of automated trading system, which will be traded in FOREX. The aim is to create a business strategy that is relatively safe, stable and profitable. Optimization and testing on historical data are a prerequisite for the deployment into real trading.
16

Návrh automatického obchodního systému na devizových trzích s využitím fraktální geometrie / Automatic Trading System on the Foreign Exchange Market Based on a Fractal Geometry

Babič, Vojtěch January 2016 (has links)
The main focus of the thesis are approaches to technical analysis, trading systems and it summarizes interesting findings, according to which a FOREX automated trading system was designed and implemented. Optimization and testing were a prerequisite for a real-world deployment, so the automated trading system was tested on historical data and some of its input parameters were optimized for maximum stability and profit.
17

Modelagem de sistemas dinamicos não lineares utilizando sistemas fuzzy, algoritmos geneticos e funções de base ortonormal / Modeling of nonlinear dynamics systems using fuzzy systems, genetic algorithms and orthonormal basis functions

Medeiros, Anderson Vinicius de 23 January 2006 (has links)
Orientadores: Wagner Caradori do Amaral, Ricardo Jose Gabrielli Barreto Campello / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Eletrica e de Computação / Made available in DSpace on 2018-08-06T08:36:39Z (GMT). No. of bitstreams: 1 Medeiros_AndersonViniciusde_M.pdf: 896535 bytes, checksum: 48d0d75d38fcbbd0f47f7c49823806f1 (MD5) Previous issue date: 2006 / Resumo: Esta dissertação apresenta uma metodologia para a geração e otimização de modelos fuzzy Takagi-Sugeno (TS) com Funções de Base Ortonormal (FBO) para sistemas dinâmicos não lineares utilizando um algoritmo genético. Funções de base ortonormal têm sido utilizadas por proporcionarem aos modelos propriedades como ausência de recursão da saída e possibilidade de se alcançar uma razoável capacidade de representação com poucos parâmetros. Modelos fuzzy TS agregam a essas propriedades as características de interpretabilidade e facilidade de representação do conhecimento. Enfim, os algoritmos genéticos se apresentam como um método bem estabelecido na literatura na tarefa de sintonia de parâmetros de modelos fuzzy TS. Diante disso, desenvolveu-se um algoritmo genético para a otimização de duas arquiteturas, o modelo fuzzy TS FBO e sua extensão, o modelo fuzzy TS FBO Generalizado. Foram analisados modelos locais lineares e não lineares nos conseqüentes das regras fuzzy, assim como a diferença entre a estimação local e a global (utilizando o estimador de mínimos quadrados) dos parâmetros desses modelos locais. No algoritmo genético, cada arquitetura contou com uma representação cromossômica específica. Elaborou-se para ambas uma função de fitness baseada no critério de Akaike. Em relação aos operadores de reprodução, no operador de crossover aritmético foi introduzida uma alteração para a manutenção da diversidade da população e no operador de mutação gaussiana adotou-se uma distribuição variável ao longo das gerações e diferenciada para cada gene. Introduziu-se ainda um método de simplificação de soluções através de medidas de similaridade para a primeira arquitetura citada. A metodologia foi avaliada na tarefa de modelagem de dois sistemas dinâmicos não lineares: um processo de polimerização e um levitador magnético / Abstract: This work introduces a methodology for the generation and optimization of Takagi-Sugeno (TS) fuzzy models with Orthonormal Basis Functions (OBF) for nonlinear dynamic systems based on a genetic algorithm. Orthonormal basis functions have been used because they provide models with properties like absence of output feedback and the possibility to reach a reasonable approximation capability with just a few parameters. TS fuzzy models aggregate to these properties the characteristics of interpretability and easiness to knowledge representation in a linguistic manner. Genetic algorithms appear as a well-established method for tuning parameters of TS fuzzy models. In this context, it was developed a genetic algorithm for the optimization of two architectures, the OBF TS fuzzy model and its extension, the Generalized OBF TS fuzzy model. Local linear and nonlinear models in the consequent of the fuzzy rules were analyzed, as well as the difference between local and global estimation (using least squares estimation) of the parameters of these local models. Each architecture had a specific chromosome representation in the genetic algorithm. It was developed a fitness function based on the Akaike information criterion. With respect to the genetic operators, the arithmetic crossover was modified in order to maintain the population diversity and the Gaussian mutation had its distribution varied along the generations and differentiated for each gene. Besides, it was used, in the first architecture presented, a method for simplifying the solutions by using similarity measures. The whole methodology was evaluated in modeling two nonlinear dynamic systems, a polymerization process and a magnetic levitator / Mestrado / Automação / Mestre em Engenharia Elétrica

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