Dans un monde industriel marqué par un contexte économique difficile, les entreprises se doivent d’étudier toutes les possibilités de réduction de coûts et d’optimisation de leur chaîne logistique. Un des champs récents d’optimisation développé dans la littérature concerne le concept de logistique inverse. Cette logistique représente la gestion des flux traversant une chaîne logistique dans le sens inverse des flux traditionnels. On y retrouve des activités liées au recyclage, à la réparation ou encore à la réutilisation de produits. Au sein de la Chaire Supply Chain, nous nous sommes donc intéressés à l’optimisation de la gestion de ces flux de retours, avec les contenants réutilisables comme objet d’étude intéressant pour nos différents partenaires. Dans ce sens, après avoir passé en revue la littérature sur le concept général de la logistique inverse, nous développons un ensemble de modèles recouvrant les combinaisons mono ou multi niveaux, mono ou multi périodes et mono ou multi contenants afin d’optimiser ces retours au sein de chaînes logistiques déjà définies. Ces modèles sont par la suite appliqués, soit fictivement pour un des modèles mono-période résolu grâce à une heuristique de décomposition développée pour des réseaux logistiques de grande taille, soit réellement chez nos partenaires pour les modèles multi-périodes résolus de façon exacte. Le but de ces applications étant d’utiliser ces modèles théoriques dans un contexte réel d’entreprise et d’en dégager les possibles bénéfices économiques mais également environnementaux grâce à la prise en compte des émissions liées au transport et au cycle de vie de ces contenants. / In an industrial world touched by a complicated economic environment, companies need to explore all opportunities for cost reduction and supply chain optimization. A recent optimization field developed in the literature concerns the concept of reverse logistics. This concept deals with the flows management through a supply chain in the opposite direction to the traditional one. It includes activities related to recycling, repair or products reuse. In partnership with the industrial of the “Chaire Supply Chain”, we are interested in optimizing these reverse flows by focusing more particularly on reusable containers. For that, we propose a literature review on the general concept of reverse logistics and develop a set of models covering combinations between single and multi-levels, single and multi-periods and single and multi-containers problems in order to optimize this type of returns within already defined supply chains. These models are then applied, either in a fictive way for a single-period one solved by a decomposition heuristic proposed for large logistics networks, or in a real way for multi-period models solved exactly and applied to our partners problematic. The purpose of these applications is to use these theoretical models in a real business in order to identify economic benefits but also environmental ones by taking into account emissions from these containers transportation and manufacturing.

Este trabalho inicia descrevendo as principais teorias de laminação que têm sido empregadas nos últimos anos na determinação das condições ideais para operação de laminadores a frio. Estas condições ideais estão ligadas a um conjunto de referências dos controladores do sistema, visando a máxima produtividade do laminador e a melhor qualidade da chapa laminada. As principais contribuições desta tese são: (i) proposta de um novo procedimento não iterativo para a determinação inicial de referências para redução em cada cadeira de um laminador de tiras a frio, originado do algoritmo iterativo do fator beta, introduzido por R. M. Guo; (ii) em seguida, é feito uso do modelo de Bland e Ford para cálculo de força e torque de laminação, utilizando o esquema de reduções sugerido pelo algoritmo de inicialização. A partir deste ponto, emprega-se o algoritmo de otimização de Nelder e Mead. A contribuição da tese para esta fase de otimização consiste na proposta da função objetivo a ser minimizada. Esta função objetivo leva em conta os principais atributos de qualidade e produtividade do laminador, ou seja, espessura, planicidade e utilização de toda a potência disponível, igualmente distribuída por todas as cadeiras; (iii) finalmente, visando garantir máxima precisão para as previsões do modelo, é proposto um algoritmo de otimização para ser utilizado em um esquema de adaptação, tendo em vista as dificuldades de se estimar duas importantes variáveis do processo de laminação: o coeficiente de atrito e o limite de escoamento. São também apresentados resultados obtidos à partir de um laminador tandem de 4 cadeiras, industrial, no qual foram implantados alguns dos métodos propostos. / This work begins describing the main rolling theories which have been employed during the recent years, in order to achieve the ideal conditions for the operation of tandem cold rolling mills. These optimum conditions are connected to a set of references used by the main systems regulators, aiming at getting the best quality of the strip and the maximum productivity of the mill. The main contributions of this thesis are: (i) proposal of a new non-iterative procedure to initial reduction calculation for each stand of a tandem cold mill, based on the iterative beta factor algorithm introduced by R.M. Guo; (ii) Use of Bland and Ford model for roll force and roll torque calculation, starting from the initial reduction schedule proposed by the non-iterative initialization algorithm and optimized by the Nelder and Mead method. The contribution of this thesis for this optimization phase consists in its proposal for an objective function to be minimized. This objective function takes into consideration the main product quality and process productivity attributes, i.e., thickness, flatness and the use of maximum available power, evenly distributed among all stands; (iii) finally, aiming at ensuring maximum precision for the model predictions, it is proposed an optimization algorithm to be used by an adaptation strategy, considering the difficulties to estimates two main rolling mill process variables: friction and yield stress coeficientes. Results extracted from an industrial four stand tandem cold mill, on which some of the proposal theories were implemented, are presented and discussed.

As unidades industriais de produção de poliolefinas operam de maneira contínua, mas precisam produzir diferentes tipos de grades poliméricos (polímeros com diferentes especificações, para diferentes aplicações). As condições de operação do reator são mantidas por um certo período de tempo para produzir um determinado grade, e periodicamente as condições são alteradas para produzir lotes de outros grades. Estas transições permitem produzir diferentes grades usando o mesmo reator, mas exige mudanças nas condições operacionais e, como consequência, o polímero produzido durante uma transição fica fora da especificação. Assim, é desejável que as transições sejam realizadas no menor tempo possível, de maneira a produzir a menor quantidade de polímero fora da especificação. Estratégias mais eficientes de operar a transição podem ser obtidas através da solução de um problema de otimização dinâmica. Neste trabalho uma função objetivo integral quadrática foi minimizada, utilizando técnicas sequenciais dinâmicas para resolução da otimização. Os resultados foram primeiramente simulados e depois otimizados para a homopolimerização e copolimerização. No caso da homopolimerização, as otimizações mostraram que para aumentar o MI é preciso aumentar a concentração de hidrogênio na alimentação. Já na copolimerização, para aumentar o MI foi preciso diminuir a concentração de hidrogênio na alimentação e aumentar a vazão de comonômero; e para diminuir a densidade foi preciso aumentar a vazão de comonômero. Observou-se que as propriedades instantâneas têm dinâmica mais rápida e agressiva que as cumulativas. Os resultados mostraram que quando a parametrização não era adequada a solução se afastava do ótimo. Foi possível notar que atuar durante 2 tempos de residência já traz uma redução significativa do tempo para o término da transição e da massa de produto fora da especificação. O perfil das propriedades da transição no sentido grade 1 - grade 2 se mostrou diferente do grade 2 - grade 1, concluindo que o perfil de uma transição depende fortemente da direção da mudança nas propriedades. / Polyolefin plants operate under continuous production, but they need to supply many types of polymer grades (polymer with different specification, used in different applications). The operating conditions are maintained constant during the production of a certain grade and need to change periodically to produce another grade. Grade transitions allow the production of different polymer grades in a single reactor, but as they require changes in the operating conditions, there is a large production of off-specification polymer. Therefore, a desired transition drives the polymer properties to the new grade in a short period of time, producing a small amount of off-specification polymer. Efficient strategies to operate the transition can be obtained by solving a problem of dynamic optimization. In this work, a quadratic integral objective function was minimized by using dynamic sequential techniques for solving optimization. The results were first simulated and then optimized for the homopolymerization and copolymerization. In the case of homopolymerization, optimizations showed that to increase the MI is necessary to increase the hydrogen concentration in the feed. In the copolymerization, to increase the MI was necessary to reduce the concentration of hydrogen in the feed and increase the comonomer flow rate; and to decrease the density was necessary to increase the comonomer flow rate. It was observed that the instantaneous properties have faster and aggressive dynamics compared to the cumulative properties. The results showed that when the parameterization was not adequate the solution moves away from the optimum. It was observed that to act for 2 residence times makes a significant reduction in the transition time completion and in the mass of product out of specification. The trajectories of the transition properties towards grade 1 - grade 2 showed different behavior compared to grade 2 - grade 1 transition, concluding that the profile of a transition depends strongly on the direction of change in the properties.

Orientador: Jorge Stolfi / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Computação / Made available in DSpace on 2018-08-23T12:30:57Z (GMT). No. of bitstreams: 1 Pereira_DanilloRoberto_D.pdf: 2771811 bytes, checksum: 6d5b092c08b5c011636be5fc2661e4a0 (MD5) Previous issue date: 2013 / Resumo: Nesta tese descrevemos um algoritmo genérico (que denominamos MSFit) capaz de estimar a pose e as deformações de modelos 3D de estruturas biológicas (bactérias, células e etc.) em imagens obtidas por meio de microscópios óticos ou de varredura eletrônica. O algoritmo usa comparação multi-escala de imagens utilizando uma métrica sensível ao contorno; e um método original de otimização não-linear. Nos nossos testes com modelos de complexidade moderada (até 12 parâmetros) o algoritmo identifica corretamente os parâmetros do modelo em 60-70% dos casos com imagens reais e entre 80-90% dos casos com imagens sintéticas / Abstract: In this thesis we describe a generic algorithm (which we call MSFit) able to estimate the pose and deformations of 3D models of biological structures (bacteria, cells, etc.) with images obtained by optical and scanning electron microscopes. The algorithm uses an image comparison metric multi-scale, that is outline-sensitive, and a novel nonlinear optimization method. In our tests with models of moderate complexity (up to 12 parameters) the algorithm correctly identifies the model parameters in 60-70 % of the cases with real images and 80-90 % of the cases with synthetic images / Doutorado / Ciência da Computação / Doutor em Ciência da Computação

This report will look at optimization under parameters of uncertainties. It will describe the subject in its wider form, then two model examples will be studied, followed by an application to an ABB product. The Monte Carlo method will be described and scrutinised, with the quasi-Monte Carlo method being favoured for large problems. An example will illustrate how the choice of Monte Carlo method will affect the efficiency of the simulation when evaluating  functions of different dimensions. Then an overview of mathematical optimization is given, from its simplest form to nonlinear, nonconvex  optimization problems containing uncertainties.A Monte Carlo simulation is applied to the design process and cost function for a custom made ABB transformer, where the production process is assumed to contain some uncertainties.The result from optimizing an ABB cost formula, where the in-parameters contains some uncertainties, shows how the price can vary and is not fixed as often assumed, and how this could influence an accept/reject decision.

Availability of and access to water and energy are key ingredients for economic and social development. Predictions show that pressure on already limited water and energy resources is expected to increase in many parts of the world as a result of growing populations, rapid urbanization, increasing pollution and climate change impacts. The water and energy systems are highly interdependent and these interlinks provide important opportunities to improve resource security and prevent inefficient decisions which could exacerbate problems even further. This thesis explores the benefits to be gained from and the drawbacks of ignoring the various interlinks. A review of several existing water-energy integration modeling methodologies shows that the different physical, temporal and spatial characteristics of the water and energy systems present several hurdles in analyzing the two resources simultaneously. This thesis overcomes many of these issues by developing a fully integrated hard-linked water-energy linear optimization model. A case study from Spain is used to demonstrate the applications of the model for simultaneous analysis of water, energy and climate change adaptation strategies. An integrated approach is shown to have several benefits including lower total costs, better resource efficiency and improved robustness for a wide range of variations in several uncertain parameters. / <p>QC 20171106</p>

Electromagnetic imaging is the problem of determining material properties from scattered fields measured away from the domain under investigation. Solving this inverse problem is a challenging task because (i) it is ill-posed due to the presence of (smoothing) integral operators used in the representation of scattered fields in terms of material properties, and scattered fields are obtained at a finite set of points through noisy measurements; and (ii) it is nonlinear simply due the fact that scattered fields are nonlinear functions of the material properties. The work described in this thesis tackles the ill-posedness of the electromagnetic imaging problem using sparsity-based regularization techniques, which assume that the scatterer(s) occupy only a small fraction of the investigation domain. More specifically, four novel imaging methods are formulated and implemented. (i) Sparsity-regularized Born iterative method iteratively linearizes the nonlinear inverse scattering problem and each linear problem is regularized using an improved iterative shrinkage algorithm enforcing the sparsity constraint. (ii) Sparsity-regularized nonlinear inexact Newton method calls for the solution of a linear system involving the Frechet derivative matrix of the forward scattering operator at every iteration step. For faster convergence, the solution of this matrix system is regularized under the sparsity constraint and preconditioned by leveling the matrix singular values. (iii) Sparsity-regularized nonlinear Tikhonov method directly solves the nonlinear minimization problem using Landweber iterations, where a thresholding function is applied at every iteration step to enforce the sparsity constraint. (iv) This last scheme is accelerated using a projected steepest descent method when it is applied to three-dimensional investigation domains. Projection replaces the thresholding operation and enforces the sparsity constraint. Numerical experiments, which are carried out using synthetically generated or actually measured scattered fields, show that the images recovered by these sparsity-regularized methods are sharper and more accurate than those produced by existing methods. The methods developed in this work have potential application areas ranging from oil/gas reservoir engineering to biological imaging where sparse domains naturally exist.

The diploma thesis deals with linear integer optimization in production logistics via mathematical programming. This tool is used for optimization of the time production schedule with a number of various jobs performed by a company with limited resources. The thesis solves the problem in conjunction with TOSHULIN, a.s. company, which is interested in solving the problem. As a result is the software implementation in which Gantt chart is created as its output.

Systematic conservation planning is an essential part of biodiversity preservation.

Målet har varit att öka andelen skrotanvändning i omsmältan med hjälp av linjärprogrammering som en optimering vid en aluminiumindustri, vilket uppnåddes. Det har gjorts en nulägesanalys om hur aluminium används, hur produktionen fungerar samt var det faller ut skrot. Följande har en teoretisk referensram upprättats med källor från tidigare problem som lösts med linjärprogrammering, en beskrivning av linjärprogrammering och en matematisk uppställning. Det har också beskrivits hur problemet ställts upp, vilka infallsvinklar som använts och de resultat som optimeringen gett. Det har även gjorts arbete kring den måluppfyllande optimeringen som presenterats efter resultatet, vilket följs av en diskussion och slutsats med rekommendationer för framtida arbete inom ämnet. Optimeringen är gjord både mot volym som målfunktion, vilket ger en ökad användning av skrotet, och med pris som målfunktion, som bidrar till en minskad kapitalbindning i skrotet som finns kvar. Dagslägets användning av skrot uppgår till cirka 30 % per år medan optimeringsmodellen gjord på endast 17 av 72 recept skulle kunna få i så mycket som 90 % av hela årets producerade skrot. En optimering på endast ett recept visar också på att det är möjligt att smälta om och producera gjutlegeringar bestående av hög andel enbart skrot. / The aim with this project was to increase the amount of used scrap in the remelt of aluminum alloys by using linear programming, which was successfully done. A status analysis about the average use and characteristics of aluminum has been described, as well as a mapping of the todays industry within the company. This is followed by a theoretical chapter containing references from previous work solved with linear programming, and a description of LP including the mathematical model. The attempt to solve this problem is carefully shown in the forthcoming chapters together with the different approaches that were used. The results are presented with analysis of each optimization, followed by a discussion and a conclusion including future recommendations. The model is used with two different objective functions to get perspective, volume to maximize the amount of used scrap and price to increase use of high valued alloys in order to decrease capital accumulation within the non-used scrap. The remelt process of today consumes about 30 % of the total scrap produced during one year. This model shows that it is possible, by having 17 out of 72 recipes, to use 90 % of all scrap. One optimization for a single recipe also proved that it is possible to produce an alloy consisting of basically scrap.