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A proliferação do comércio electrónico nas últimas décadas veio abrir portas a novas oportunidades de negócio que permitiram a algumas empresas atingir um novo patamar de produtividade, alcançando diferentes públicos e novos clientes. O envio de publicidade por correio electrónico (email marketing) é uma forma que diversas empresas encontraram de divulgar os seus produtos e serviços na Internet, atingindo desta forma um enorme número de potenciais clientes a um custo provavelmente mais reduzido. Com o aparecimento destas novas formas de negócio online foram criadas empresas direccionadas apenas para a publicidade na Internet (web-marketing). Com este estudo pretendemos obter um modelo que identifique satisfatoriamente os utilizadores de email marketing. Para este efeito analisaram-se dados relativos a listas de subscritores recolhidas ...
Este relatório resulta de um projeto desenvolvido numa Empresa muito jovem de Web Marketing sediada no Porto mas que se encontra representada um pouco por todo o mundo. Foi-nos proposto identificar, através de ferramentas da Estatística, os factores facilitadores do consumo de email marketing. Depressa nos apercebemos da ambição de tal projeto. Depressa nos apercebemos que não seríamos capazes de dar a resposta a este problema. Tentamos aproximações às soluções do problema. As soluções, apresentadas neste trabalho de síntese, passam pelo entendimento do problema no contexto em que este se insere, marketing/email marketing, pela seleção das variáveis disponíveis na base de dados da Empresa e pela sua análise. Aplicamos técnicas descritivas, univariadas e multivariadas e técnicas inferenciais. Usamos técnicas paramétricas, muito poucas, ...
Nesta dissertação, as duas abordagens evolucionárias mais conhecidas e frequentemente aplicadas a problemas de optimização são consideradas: as Estratégias Evolutivas e os Algoritmos Genéticos. Estas abordagens apresentam como principal desvantagem tempos de computação elevados mas, por outro lado, exibem uma grande flexibilidade na modulação de problemas de engenharia. As vantagens e os inconvenientes de cada uma das abordagens para diferentes tipos de problemas de optimização foram investigadas, nomeadamente ao nível da representação do espaço das soluções e no tratamento das restrições. Usualmente, em engenharia, os problemas são formulados com um único objectivo, em geral, o custo. Contudo, podem existir outros objectivos que, quando considerados, transformam o problema em optimização multi-objectivo. Nesta classe de problemas, em ...
Several evolutionary approaches have been applied to unconstrained global optimization problems with significant success. These algorithms mimic the natural evolution of the species in biological systems and do not require any continuity or convexity properties of the problem being solved. Moreover, unlike conventional algorithms, only information regarding the objective function is required to perform the search. Evolution strategies proved to be one of the most efficient evolutionary approach to global optimization. However, these algorithms have several parameters which the setting is not simple. Thus, it is crucial to investigate how to set dynamically these parameters during the search. In this paper, a new parameter-less evolution strategy, which has only one single parameter to set, is proposed. The influence of this parameter i...
The start of operation of several large-aperture telescopes has motivated several groups around the world to conduct deep large imaging surveys, complementing other wide-area but shallower surveys. A special class of imaging surveys are the public ones such as those being conducted by the ESO Imaging Survey (EIS) project established with the primary objective of providing to the ESO community large datasets from which samples can be drawn for VLT programs. To date several surveys have been carried out providing multi-passband optical data over relatively large areas to moderate depth, deep optical/infrared surveys of smaller fields as well as observations of a large number of selected stellar fields. These surveys have produced a large amount of well-defined datasets with known limits from which a variety of data products have been e...
Solving multiobjective engineering problems is, in general, a difficult task. In spite of the success of many approaches, elitism has emerged has an effective way of improving the performance of algorithms. In this paper, a new elitist scheme, by which it is possible to control the size of the elite population, as well as the concentration of points in the approximation to the Pareto-optimal set, is introduced. This new scheme is tested on several multiobjective problems and, it proves to lead to a good compromise between computational time and size of the elite population.
The problem of tuning nonlinear dynamical systems parameters, such that the attained results are considered good ones, is a relevant one. This article describes the development of a gait optimization system that allows a fast but stable robot quadruped crawl gait. We combine bio-inspired Central Patterns Generators (CPGs) and Genetic Algorithms (GA). CPGs are modelled as autonomous differential equations, that generate the necessar y limb movement to perform the required walking gait. The GA finds parameterizations of the CPGs parameters which attain good gaits in terms of speed, vibration and stability. Moreover, two constraint handling techniques based on tournament selection and repairing mechanism are embedded in the GA to solve the proposed constrained optimization problem and make the search more efficient. The experimental resul...
An initial understanding of the application of an evolutionary approach to baker’s yeast fermentation parameters estimation is described. This problem has a nonlinear and multimodal nature. Thus, a global optimization technique, such the evolution strategies, must be used as an approximation to the global optimum. The process is modelled by a set of differential-algebraic equations to obtain the six state variables concentration profiles, in a well-mixed reactor. The state variables profiles are obtained using parameters usually referred in literature: seven kinetic parameters and nine yield coefficients. A new problem of optimization can be formulated with the objective of minimizing the overall sum of the squared residuals that adjust the simulation results to the experimental data. With the evolutionary approach not only the paramet...
There is a general consensus that the rational use of available resources is, nowadays, an important task, since project managers are interested in the maximization of profit and the minimization of risk. In this work, it is proposed a multi-objective model to optimize the use of resources in a stochastic environment. In this multi-objective formulation the aim is to minimize the project duration and the total project cost at the same time. In the future, we intend to solve this problem using multi-objective evolutionary algorithms.
This paper presents a gait multi-objective optimization system that combines bio-inspired Central Patterns Generators (CPGs) and a multi-objective evolutionary algorithm. CPGs are modeled as autonomous differential equations, that generate the necessary limb movement to perform the required walking gait. In order to optimize the walking gait, four conflicting objectives are considered, simultaneously: minimize the body vibration, maximize the velocity, maximize the wide stability margin and maximize the behavioral diversity. The results of NSGA-II for this multi-objective problem are discussed. The effect of the inclusion of a behavioral diversity objective in the system is also studied in terms of the walking gait achieved. The experimental results show the effectiveness of this multi-objective approach. The several walking gait solut...
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