Computational tools such as finite element analysis and simulation are commonly used for system performance analysis and validation. It is often impractical to rely exclusively on the high-fidelity simulation model for design activities because of high computational costs. Mathematical models are typically constructed to approximate the simulation model to help with the design activities. Such models are referred to as “metamodel.” The process of constructing a metamodel is called “metamodeling.” Metamodeling, however, faces eminent challenges that arise from high-dimensionality of underlying problems, in addition to the high computational costs and unknown function properties (that is black-box functions) of analysis/simulation. The combination of these three challenges defines the so-called high-dimensional, computationally-expensive, and black-box (HEB) problems. Currently there is a lack of practical methods to deal with HEB problems. This dissertation, by means of surveying existing techniques, has found that the major deficiency of the current metamodeling approaches lies in the separation of the metamodeling from the properties of underlying functions. The survey has also identified two promising approaches - mapping and decomposition - for solving HEB problems. A new analytic methodology, radial basis function–high-dimensional model representation (RBF-HDMR), has been proposed to model the HEB problems. The RBF-HDMR decomposes the effects of variables or variable sets on system outputs. The RBF-HDMR, as compared with other metamodels, has three distinct advantages: 1) fundamentally reduces the number of calls to the expensive simulation in order to build a metamodel, thus breaks/alleviates exponentially-increasing computational difficulty; 2) reveals the functional form of the black-box function; and 3) discloses the intrinsic characteristics (for instance, linearity/nonlinearity) of the black-box function. The RBF-HDMR has been intensively tested with mathematical and practical problems chosen from the literature. This methodology has also successfully applied to the power transfer capability analysis of Manitoba-Ontario Electrical Interconnections with 50 variables. The test results demonstrate that the RBF-HDMR is a powerful tool to model large-scale simulation-based engineering problems. The RBF-HDMR model and its constructing approach, therefore, represent a breakthrough in modeling HEB problems and make it possible to optimize high-dimensional simulation-based design problems.

Made available in DSpace on 2016-06-02T19:06:19Z (GMT). No. of bitstreams: 1 6441.pdf: 3762020 bytes, checksum: cf0babba26cd55b52382a3a068029d68 (MD5) Previous issue date: 2014-10-13 / Universidade Federal de Sao Carlos / Maintaining legacy systems is a complex and expensive activity for many companies. An alternative to this problem is the Architecture-Driven Modernization (ADM), proposed by the OMG (Object Management Group). ADM is a set of principles that support the modernization of systems using models. The Knowledge Discovery Metamodel (KDM) is the main ADM metamodel and it is able to represent various characteristics of a system, such as source code, configuration files and GUI. Through a reverse engineering process supported by tools is possible to extract knowledge from legacy source code and store it in KDM metamodel instances. Another metamodel that is important to this project is the Structured Metrics Metamodel (SMM) that allows the specification of metrics and also the representation of the measurements results performed on KDM models. When we decide to modernize a legacy system, an alternative that aims to improve concerns modularization of a system is the Aspect-Oriented Programming. Considering this alternative, the main goal of this project is to present an approach to defining and computing concern metrics in instances of KDM metamodel. This kind of measurement needs a prior concern mining that make notes on system components indicating concerns which it implements. To achieve the project objective, a complete approach to measure concerns using ADM models was developed, this approached is composed by an extension of KDM metamodel for representing Aspect- Oriented Software (AO-KDM), a concern metrics library in SMM format (CCML) developed in order to be parameterized by the Modernization Engineer. Therefore, the metrics defined in this project can be reused in other projects. Furthermore, we have developed a tool (CMEE) capable of handling parameterization annotations (notes about concerns made by the mining tools) that allows that models annotated by different mining tools could be measured by SMM metrics. / Manter sistemas legados é uma atividade complexa e cara para muitas empresas. Uma alternativa para este problema é a Modernização Dirigida à Arquitetura (Architecture- Driven Modernization - ADM), proposta pelo OMG (Object Management Group). A ADM consiste em um conjunto de princípios que apoiam a modernização de sistemas utilizando modelos. O Knowledge Discovery Metamodel (KDM) é o principal metamodelo da ADM e é capaz de representar diversas características de um sistema, como código-fonte, arquivos de configuração e de interface gráfica. Por meio de um processo de engenharia reversa apoiado por ferramentas é possível extrair conhecimento do código-fonte legado e armazená-lo em instâncias do metamodelo KDM. Outro metamodelo da ADM pertinente a este projeto é o Structured Metrics Metamodel (SMM) que torna possível a especificação de métricas e também a representação dos resultados de medições realizadas em modelos KDM. Quando decide-se modernizar um sistema legado, uma alternativa que procura melhorar o nível de modularização dos interesses de um sistema é a orientação a aspetos. Considerando essa alternativa, o objetivo deste projeto é apresentar uma abordagem para definição e aplicação de métricas de interesse em instâncias do metamodelo KDM. Esse tipo de medição precisa de uma mineração de interesses prévia, que realiza anotações nos componentes do sistema indicando qual interesse ele implementa. Para alcançar o objetivo do projeto, foi desenvolvida uma abordagem completa de medição de interesses utilizando modelos da ADM, composta por uma extensão do KDM para a representação de software orientado a aspectos (AO-KDM), uma biblioteca de métricas de interesses no formato SMM (CCML) desenvolvida com o intuito de ser parametrizável pelo Engenheiro de Modernização. Portanto, as métricas definidas neste projeto podem ser reusadas em outros projetos. Além disso, foi desenvolvida uma ferramenta de apoio computacional (CMEE) capaz de lidar com parametrização de anotações (anotações de interesses realizadas por ferramentas de mineração) que permite que modelos anotados com diferentes ferramentas de mineração possam ser medidos por métricas SMM.

Made available in DSpace on 2016-06-02T19:06:20Z (GMT). No. of bitstreams: 1 6500.pdf: 5345644 bytes, checksum: e886844b4ba61e58d704a8babf113721 (MD5) Previous issue date: 2014-10-21 / Maintaining legacy systems is a complex and expensive activity for many companies. A recently proposal to solve this problem is Architecture-Driven Modernization (ADM), proposed by Object Management Group (OMG). The ADM consists of a set of concepts and standard metamodels that support systems modernization using models. The Knowledge Discovery Metamodel (KDM) is the main metamodel of ADM, it can represent many artifacts of a legacy system, such as source code, architecture, user interface, configuration files and business process. In general, legacy systems have crosscutting concerns, it can show source code problems like tangling and scattering, and it raises the maintenance costs. The aspect orientation is an alternative to improve crosscutting concerns modularization. Thus, in this dissertation is presented the term Aspect Oriented Modernization that uses the aspect oriented concepts in the ADM context. This modernization process consists in modularize legacy systems with aspects represented in model level. To achieve this goal, in this work were performed a lightweight and a heavyweight extension in the KDM metamodel, to analyze which one would present a better performance if used by Modernization Engineers. The evaluation of these extensions was performed by a case study that considered the modernization with aspects of a small-sized system. To evaluate the case study in both extensions, a set of comparison criteria were created to support the software engineers in choosing the best extension mechanism, according to their needs. In the context of this dissertation an experimental study were developed that aimed reproducing the scenarios that the modernization engineers had to perform maintenances and developing new refactorings in a aspect oriented KDM model. The experiment data considered the development time of the activities and the found number of errors. Finally, it was noticed that the extension mechanism to be choose will depend on the context that it will be applied, however, considering the approach studied here the best extension mechanism is the heavyweight one. / Manter sistemas legados é uma atividade complexa e onerosa para muitas empresas. Uma proposta recente para esse problema é a Modernização Dirigida à Arquitetura (Architecture-Driven Modernization - ADM), proposta pela OMG (Object Management Group). A ADM consiste em um conjunto de princípios e metamodelos padrões que apoiam a modernização de sistemas utilizando modelos. O Knowledge Discovery Metamodel (KDM) é o principal metamodelo da ADM, podendo representar diversos artefatos de um sistema, como código-fonte, arquitetura, interface de usuário, arquivos de configuração e processos de negócio. Em geral, sistemas legados possuem interesses transversais, apresentando problemas de entrelaçamento e espalhamento de código, o que eleva os custos de manutenção. A orientação a aspectos é uma alternativa para melhorar a modularização de interesses transversais. Mediante isso, neste trabalho é apresentado o termo Modernização Orientada a Aspectos que utiliza os conceitos da orientação a aspectos na ADM. Essa modernização consiste em remodularizar sistemas legados utilizando aspectos representados em nível de modelo. Para atingir esse objetivo, foi realizada uma extensão leve e outra pesada do metamodelo KDM, para analisar em qual das duas o desempenho dos engenheiros de modernização seria melhor. Para fazer a avaliação das extensões, foi realizado um estudo de caso levando em consideração a modernização com aspectos em um sistema de pequeno porte. Com o objetivo de avaliar o estudo de caso usando as duas extensões, foram desenvolvidos critérios de comparação que auxiliassem os engenheiros de software a escolher qual dos dois mecanismos de extensão utilizar em seu projeto. Foi feito também um estudo experimental que buscou reproduzir os cenários em que engenheiros de modernização tivessem que realizar manutenções e desenvolver novas refatorações em um modelo KDM orientado a aspectos. Os dados do experimento foram avaliados em relação ao tempo de desenvolvimento das atividades e quantidade de erros encontrados. Por fim, percebeu-se que o mecanismo de extensão a ser utilizado vai depender do contexto em que ele será aplicado, mas, para o domínio aqui estudado a extensão que melhor atendeu aos requisitos foi a pesada.

Submitted by Luciana Ferreira (lucgeral@gmail.com) on 2016-04-18T14:16:18Z No. of bitstreams: 2 Dissertação - Marcos Alves Vieira - 2016.pdf: 4271419 bytes, checksum: 4b956a9d65582e1f1e1685988c493f7c (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) / Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2016-04-18T14:17:45Z (GMT) No. of bitstreams: 2 Dissertação - Marcos Alves Vieira - 2016.pdf: 4271419 bytes, checksum: 4b956a9d65582e1f1e1685988c493f7c (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) / Made available in DSpace on 2016-04-18T14:17:45Z (GMT). No. of bitstreams: 2 Dissertação - Marcos Alves Vieira - 2016.pdf: 4271419 bytes, checksum: 4b956a9d65582e1f1e1685988c493f7c (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) Previous issue date: 2016-02-26 / Fundação de Amparo à Pesquisa do Estado de Goiás - FAPEG / Advances in electronics allow the creation of everyday devices with computing capabilities, called smart objects. Smart objects assist people in carrying out a variety of tasks and compose smart spaces. When smart spaces are confined to a certain area, they can be referred to as fixed smart spaces. In complement of these, personal smart spaces are composed by the smart objects a user carries with himself, hence with boundaries moving along with his owner. However, user mobility and the increasing number of smart spaces, fostered also by the Internet of Things (IoT) and the Web of Things (WoT), can lead to smart spaces overlap, where a certain smart object is configured in different smart spaces, whether fixed or personal. In addition, smart spaces are complex and difficult to model and maintain, as, among other factors, they have to deal with different smart objects. This thesis proposes the use of Model-Driven Engineering to enable modeling of ubiquitous computing scenarios, considering the coexistence between fixed and personal smart spaces. Its contributions include a metamodel for modeling scenarios composed by personal smart spaces and fixed smart spaces, together with a language and an algorithm, aiming at determining the access order to the resources of a ubiquitous computing scenario. The validation of the proposal was carried out based on the results of a Systematic Literature Review, conducted in order to identify metamodel validation methods most commonly used by researchers within the field. Thus, scenarios were modeled with the aid of modeling tools, which were constructed to produce models, conforming to the proposed metamodels. An implementation in Java enabled to validate the access policy language as well as its processing algorithm. / Os avanços em eletrônica estão possibilitando a criação de dispositivos do cotidiano com capacidades computacionais, chamados de objetos inteligentes. Os objetos inteligentes auxiliam as pessoas na realização de suas tarefas e compõem os espaços inteligentes. Quando os espaços inteligentes são restritos a uma determinada área, eles são denominados espaços inteligentes fixos. Em complementação a estes, os espaços inteligentes pessoais são formados pelos objetos inteligentes que um usuário carrega consigo e seus limites se movem juntamente com seu “dono”. No entanto, a mobilidade dos usuários e o crescente número de espaços inteligentes, fomentados também pela Internet das Coisas e Web das Coisas, podem levar à sobreposição de espaços inteligentes, onde um determinado objeto inteligente pode ser utilizado em diferentes espaços inteligentes, sejam estes fixos ou pessoais. Além disso, espaços inteligentes são complexos e difíceis de modelar e manter, pois, entre outros fatores, precisam lidar com diferentes objetos inteligentes. Este trabalho propõe o uso de técnicas de Engenharia Dirigida por Modelos para possibilitar a modelagem de cenários de computação ubíqua, considerando a coexistência entre espaços inteligentes fixos e pessoais. As contribuições deste trabalho incluem: um metamodelo para modelagem de cenários compostos por espaços inteligentes pessoais e espaços inteligentes fixos; e uma linguagem e um algoritmo, com objetivo de permitir determinar a ordem de acesso aos recursos de um cenário de computação ubíqua. A validação da proposta se deu com base nos resultados de uma Revisão Sistemática da Literatura, que foi conduzida com objetivo de identificar as formas de validação e avaliação de metamodelos mais utilizadas pelos pesquisadores da área. Dessa forma, cenários foram modelados com o auxílio de ferramentas de modelagem construídas para produzir modelos em conformidade com os metamodelos propostos. Uma implementação em linguagem Java permitiu validar tanto a linguagem de políticas de acesso quanto seu algoritmo de processamento.

Submitted by Franciele Moreira (francielemoreyra@gmail.com) on 2018-02-01T11:58:08Z No. of bitstreams: 2 Dissertação - Weider Alves Barbosa - 2017.pdf: 3232518 bytes, checksum: 2a1f899f2cf8bf0f76707049183a9888 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2018-02-02T09:42:07Z (GMT) No. of bitstreams: 2 Dissertação - Weider Alves Barbosa - 2017.pdf: 3232518 bytes, checksum: 2a1f899f2cf8bf0f76707049183a9888 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2018-02-02T09:42:07Z (GMT). No. of bitstreams: 2 Dissertação - Weider Alves Barbosa - 2017.pdf: 3232518 bytes, checksum: 2a1f899f2cf8bf0f76707049183a9888 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2017-10-30 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / This thesis presents an approach to construct model execution machines based on the concept of Domain Specific Virtual Machines (DSVMs), focusing on the control middleware layer that is responsible for the control of model execution. In order to build this layer, we used techniques derived from model-driven engineering (MDE), in order to take advantage of the fact that DSVMs can both interpret models directly and be constructed using models. Another concept used in the proposed approach is the Separation of Concerns, separating the execution model from the knowledge of the application domain. In this sense, the main objective of this work is to propose an approach that unifies the MDE techniques and separation of concerns for the construction of DSVMs, thus allowing to express both the structure and operational semantics of the middleware. As a result, an instance of the control layer of a DSVM for the user-centric communication domain is displayed. We also present the results of a performance evaluation that was carried out to analyze the impact of proposed approach on the execution time. / Esta dissertação apresenta uma abordagem para construção de máquinas de execução de modelos baseadas no conceito de Domain Specific Virtual Machines (DSVMs), com foco na camada de middleware de controle, que é responsável pelo controle de execução de modelos. Para construir essa camada, foram utilizadas técnicas provenientes da engenharia dirigida por modelos (MDE), visando aproveitar o fato de que DSVMs podem tanto interpretar modelos diretamente, quanto ser construída por meio de modelos. Outro conceito utilizado na abordagem proposta é a separação de interesses (Separation of Concerns), separando o modelo de execução do conhecimento de domínio de aplicação. Neste sentido, o objetivo principal deste trabalho é propor uma abordagem que faça a união das técnicas MDE e separação de interesses para construção de DSVMs, permitindo assim expressar tanto a estrutura quanto a semântica operacional do middleware. Como resultado, é apresentada uma instância da camada de controle de uma DSVM para o domínio de comunicação centrada no usuário. Também são apresentados os resultados de uma avaliação de desempenho realizada para analisar a abordagem proposta sobre o tempo de execução.

Submitted by Marlene Santos (marlene.bc.ufg@gmail.com) on 2016-09-16T17:35:04Z No. of bitstreams: 2 Dissertação - Flayson Potenciano e Silva - 2016.pdf: 6563517 bytes, checksum: 7f7a3d166741057427f2d333473af546 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2016-09-19T11:17:33Z (GMT) No. of bitstreams: 2 Dissertação - Flayson Potenciano e Silva - 2016.pdf: 6563517 bytes, checksum: 7f7a3d166741057427f2d333473af546 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2016-09-19T11:17:33Z (GMT). No. of bitstreams: 2 Dissertação - Flayson Potenciano e Silva - 2016.pdf: 6563517 bytes, checksum: 7f7a3d166741057427f2d333473af546 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2016-09-06 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / This dissertation presents a requirement representation approach for Dynamic Software Product Lines (DSPLs). DSPLs are oriented towards the designing of adaptive applications and each requirement is represented as a feature. Traditionally, features are represented in a Software Product Line (SPL) by a Feature Model (FM). Nonetheless, such a model does not originally support dynamic features representation. This dissertation proposes an extension to FM by adding a representation for dynamic feature to it so that the model can have a higher expressivity regarding the context change conditions and the application itself. Therefore, a metamodel based on Ecore meta-metamodel has been developed to enable the definition of both Dynamic Feature Models (proposed extension to FM) and Dynamic Feature Configurations (DFC), the latter used to describe the possible configuration of products at-runtime. In addition to a representation for dynamic features and the metamodel, this dissertation provides a tool that interprets the proposed model and allows Dynamic Feature Models design. Simulations involving dynamic feature state changes have been carried out, considering scenarios of a ubiquitous monitoring application for homecare patients. / Esta dissertação apresenta uma abordagem de representação de requisitos para Linhas de Produto de Software Dinâmicas (LPSD). LPSDs são voltadas para a produção de aplicações adaptativas e cada requisito é representado como uma característica. Tradicionalmente, características são representadas em uma Linha de Produto de Software (LPS) por meio de um Modelo de Características (MC). Tal modelo, no entanto, não possui, originalmente, suporte para a representação de características dinâmicas. Esta dissertação propõe uma extensão ao MC, incorporando uma representação para as características dinâmicas, de forma que o modelo tenha maior expressividade quanto às condições de mudanças de contexto e da própria aplicação. Para isso, um metamodelo baseado no meta-metamodelo Ecore foi desenvolvido, para possibilitar a definição tanto de Modelos de Características Dinâmicas (extensão do MC proposta) quanto também de Modelos de Configuração de Características Dinâmicas (MCC-D), estes utilizados para descrever as possíveis configurações dos produtos em tempo de execução. Além de uma representação para características dinâmicas e do metamodelo, essa dissertação traz como contribuição uma ferramenta que interpreta o metamodelo proposto e permite a construção de Modelos de Características Dinâmicas. Simulações envolvendo mudanças de estado das configurações de características dinâmicas foram realizadas, considerando cenários de uma aplicação ubíqua de monitoramento de pacientes domiciliares.

Dans le domaine d’optimisation de forme de structures, la réduction des coûts et l’amélioration des produits sont des défis permanents à relever. Pour ce faire, le procédé de mise en forme doit être optimisé. Optimiser le procédé revient alors à résoudre un problème d’optimisation. Généralement ce problème est un problème d’optimisation multicritère très coûteux en terme de temps de calcul, où on cherche à minimiser plusieurs fonctions coût en présence d’un certain nombre de contraintes. Pour résoudre ce type de problème, on a développé un algorithme robuste, efficace et fiable. Cet algorithme, consiste à coupler un algorithme de capture de front de Pareto (NBI ou NNCM) avec un métamodèle (RBF), c’est-à-dire des approximations des résultats des simulations coûteuses. D’après l’ensemble des résultats obtenus par cette approche, il est intéressant de souligner que la capture de front de Pareto génère un ensemble des solutions non dominées. Pour savoir lesquelles choisir, le cas échéant, il est nécessaire de faire appel à des algorithmes de sélection, comme par exemple Nash et Kalai-Smorodinsky. Ces deux approches, issues de la théorie des jeux, ont été utilisées pour notre travail. L’ensemble des algorithmes sont validés sur deux cas industriels proposés par notre partenaire industriel. Le premier concerne un modèle 2D du fond de la canette (elasto-plasticité) et le second est un modèle 3D de la traverse (élasticité linéaire). Les résultats obtenus confirment l’efficacité de nos algorithmes développés. / One of the current challenges in the domain of the multiobjective shape optimization is to reduce the calculation time required by conventional methods. The high computational cost is due to the high number of simulation or function calls required by these methods. Recently, several studies have been led to overcome this problem by integratinga metamodel in the overall optimization loop. In this thesis, we perform a coupling between the Normal Boundary Intersection -NBI- algorithm and The Normalized Normal constraint Method -NNCM- algorithm with Radial Basis Function -RBF- metamodel in order to have asimple tool with a reasonable calculation time to solve multicriteria optimization problems. First, we apply our approach to academic test cases. Then, we validate our method against two industrial cases, namely, shape optimization of the bottom of a can undergoing nonlinear elasto-plastic deformation and an optimization of an automotive twist beam. Then, in order to select solutions among the Pareto efficient ones, we use the same surrogate approach to implement a method to compute Nash and Kalai-Smorodinsky equilibria.

Dans le contexte actuel de globalisation des marchés, le processus classique de conception par essais et erreurs n'est plus capable de répondre aux exigences de plus en plus accrues en termes de délais très courts, réduction des coûts de production, etc. L'outil d'optimisation propose une réponse à ces questions, en accompagnant les ingénieurs dans la tâche de conception optimale.L'objectif de cette thèse est centré sur la conception optimale des systèmes complexes. Deux approches sont abordées dans ce travail: l'optimisation par modèles de substitution et la conception optimale basée sur la décomposition des systèmes complexes.L'utilisation de la conception assistée par ordinateur (CAO) est devenue une pratique régulière dans l’industrie. La démarche d'optimisation basée sur modèles de substitution est destinée à répondre à l'optimisation des dispositifs bénéficiant d’une telle modélisation précise, mais couteuse en temps de calcul.Les chaînes de traction ferroviaire sont trop complexes pour être traités comme un tout. La décomposition de ces systèmes s’impose en vue de simplifier le problème et de repartir la charge de calcul. Des stratégies appropries à la résolution de telles structures ont été analysées dans ce travail. Ces approches permettent à chaque équipe de spécialistes de travailler de façon autonome à l'objet de leur expertise.Les approches d'optimisation développées au sein de ce travail ont été appliquées pour résoudre plusieurs problèmes d'optimisation électromagnétiques, ainsi que la conception optimale d’un système de traction ferroviaire de la Société Alstom / Within a globalized market context, the classical trial-and-error design process is no longer capable of answering to the ever-growing demands in terms of short deadlines, reduced production costs, etc. The optimization tool presents itself as an answer to these issues, accompanying the engineers in the optimal design task.The focus of this thesis is centered on the optimal design of complex systems. Two main optimization approaches are addressed within this work: the metamodel-based design optimization and the decomposition-based complex systems optimal design.The use of computer-aided design/engineering (CAD/CAE) software has become a regular practice in the engineering design process. The metamodel-based optimization approach is intended to address the optimization of devices represented by such accurate but computationally expensive simulation models, as the finite element analysis (FEA) in electromagnetics.Engineering systems such as railway traction systems are too complex to be addressed as a whole. The decomposition-based optimization strategies are intended to address the optimal design of such systems. The decomposition of such systems is required in order to simplify the problem and to distribute the computational burden across the decomposed structure. Appropriate multi-level strategies have been identified and analyzed within this work. Such approaches allow each team of specialists to work independently at the object of their expertise.The optimization approaches developed within this work are applied for solving several electromagnetic optimization problems and a railway traction system optimal design problem of the Alstom Company

Multidisciplinary design optimization (MDO) can be used in computer aided engineering (CAE) to efficiently improve and balance performance of automotive structures. However, large-scale MDO is not yet generally integrated within automotive product development due to several challenges, of which excessive computing times is the most important one. In this thesis, a metamodel-based MDO process that fits normal company organizations and CAE-based development processes is presented. The introduction of global metamodels offers means to increase computational efficiency and distribute work without implementing complicated multi-level MDO methods. The presented MDO process is proven to be efficient for thickness optimization studies with the objective to minimize mass. It can also be used for spot weld optimization if the models are prepared correctly. A comparison of different methods reveals that topology optimization, which requires less model preparation and computational effort, is an alternative if load cases involving simulations of linear systems are judged to be of major importance. A technical challenge when performing metamodel-based design optimization is lack of accuracy for metamodels representing complex responses including discontinuities, which are common in for example crashworthiness applications. The decision boundary from a support vector machine (SVM) can be used to identify the border between different types of deformation behaviour. In this thesis, this information is used to improve the accuracy of feedforward neural network metamodels. Three different approaches are tested; to split the design space and fit separate metamodels for the different regions, to add estimated guiding samples to the fitting set along the boundary before a global metamodel is fitted, and to use a special SVM-based sequential sampling method. Substantial improvements in accuracy are observed, and it is found that implementing SVM-based sequential sampling and estimated guiding samples can result in successful optimization studies for cases where more conventional methods fail.

Diploma thesis is focused on advanced reliability analysis of structures solved by non--linear finite element analysis. Specifically, semi--probabilistic methods for determination of design value of resistance, sensitivity analysis and surrogate model created by polynomial chaos expansion are described in the diploma thesis. Described methods are applied on prestressed reinforced concrete roof girder.