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Search Results: 1 - 10 of 383879 matches for " Lúcia Valéria Ramos de;Neves-Jr "
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Um modelo híbrido (CLP-MILP) para scheduling de opera??es em polidutos
Magat?o, Leandro;Arruda, Lúcia Valéria Ramos de;Neves-Jr, Flávio;
Pesquisa Operacional , 2008, DOI: 10.1590/S0101-74382008000300007
Abstract: this work is motivated by the need of optimization in the pipeline-oil distribution scenario. the considered problem involves the short-term scheduling of activities in a specific pipeline. the pipeline is 93.5 km in length, and it connects refinery and harbor tankfarms, conveying different types of commodities (gasoline, diesel, kerosene, etc). an optimization model was developed to determine the pipeline scheduling with improved efficiency. such model combines constraint logic programming (clp) and mixed integer linear programming (milp) in an integrated clp-milp framework. the proposed model uses decomposition strategies, continuous time representation, and intervals that represent time constraints (time windows). real cases were solved in a reduced computational time (order of seconds). the computational results have demonstrated that the model is able to define new operational points to the pipeline, providing significant cost saving. indeed the clp-milp model is an efficient tool to aid the operational decision-making within this real-world pipeline scenario.
Um método evolucionário para sintonia de controladores PI/PID em processos multivariáveis
Arruda, Lúcia Valéria R. de;Swiech, Maria Cristina Szpak;Neves-Jr, Flávio;Delgado, Myriam Regattieri;
Sba: Controle & Automa??o Sociedade Brasileira de Automatica , 2008, DOI: 10.1590/S0103-17592008000100001
Abstract: nonlinear multiple-input multiple-output (mimo) processes which are common in industrial plants are characterized by significant interactions and nonlinearities among their variables. thus, the tuning of several controllers in complex industrial plants is a challenge for process engineers and operators. this paper addresses the problem of simultaneously tuning n proportional-integral-derivative (pi/pid) controllers in a coupled multivariable process as a multi-criteria optimization problem. a multi objective genetic algorithm modified by a niching technique with castes formation is proposed to solve this problem. the optimization is carried out in two levels. in the first level a local function that considers both the integral time squared error (itse) and the minimum variance criteria is computed to separately evaluate the performance of each closed loop. thereafter, a global cost function that considers all the loops is used to compute a set of solutions (a set of pi/pid parameters) to the optimization problem. the proposed system was applied to the control of a fluid catalytic cracking (fcc) unit, and its performance was compared to dynamic matrix control (dmc). the results show the applicability and effectiveness of the proposed method.
Um modelo de otimiza??o da opera??o de terminais petrolíferos usando a teoria das restri??es como pré-processamento
Boschetto, Suelen Neves;Lüders, Ricardo;Neves Jr., Flávio;Arruda, Lúcia Valéria Ramos de;
Pesquisa Operacional , 2009, DOI: 10.1590/S0101-74382009000100001
Abstract: in the scheduling of oil transfer operations for harbor plants containing ships, piers, tanks and pipelines, an optimization model is frequently used. however, due to the complexity involved, computational time is a real concern. in this paper, a mixed integer linear programming model (milp) found in the literature is studied and a preprocessing procedure is proposed. this procedure is based on the theory of constraints (toc), which is used to reduce the model compilation time. since the problem bottleneck is identified, the corresponding constraints are not considered in the preprocessing step. an analysis based on lp dual price is also carried out to verify actions taken in the preprocessing step. although optimality cannot be assured, the results obtained show a minor deviation from the optimal solution but with a significant computational time gain.
A multiagent simulator for supporting logistic decisions of unloading petroleum ships in habors
Brito, Robison Cris;Tacla, Cesar Augusto;Arruda, Lúcia Valéria Ramos de;
Pesquisa Operacional , 2010, DOI: 10.1590/S0101-74382010000300012
Abstract: this work presents and evaluates the performance of a simulation model based on multiagent system technology in order to support logistic decisions in a harbor from oil supply chain. the main decisions are concerned to pier allocation, oil discharge, storage tanks management and refinery supply by a pipeline. the real elements as ships, piers, pipelines, and refineries are modeled as agents, and they negotiate by auctions to move oil in this system. the simulation results are compared with results obtained with an optimization mathematical model based on mixed integer linear programming (milp). both models are able to find optimal solutions or close to the optimal solution depending on the problem size. in problems with several elements, the multiagent model can find solutions in seconds, while the milp model presents very high computational time to find the optimal solution. in some situations, the milp model results in out of memory error. test scenarios demonstrate the usefulness of the multiagent based simulator in supporting decision taken concerning the logistic in harbors.
Redes dinamicas cognitivas aplicadas no controle supervisório de um fermentador
Mendon?a, Márcio;Arruda, L. V. R.;Neves-Jr, Flávio;
Sba: Controle & Automa??o Sociedade Brasileira de Automatica , 2011, DOI: 10.1590/S0103-17592011000400003
Abstract: this paper uses dynamic cognitive networks (dcn) as an intelligent tool for supervisory control. the dcns are an evolution of fuzzy cognitive maps (fcm). intelligent systems and tools use expert knowledge to build models with inference and / or decision taking abilities. a supervisory control architecture for an alcoholic fermentation process is developed from the acquisition of empirical knowledge from an expert. the objective of the supervisor is to operate the process in normal and critical situations. for this, we propose the use of a dcn model with new types of concepts and relationships that not only represent cause-effect as in fcm models. simulation results are presented to validate the architecture developed.
Identifica??o genética de modelos por pólos e zeros baseada no compromisso entre os erros de polariza??o e variancia
Arruda, L.V.R.;Fávaro, Sílvio;Neves-Jr., F.;
Sba: Controle & Automa??o Sociedade Brasileira de Automatica , 2003, DOI: 10.1590/S0103-17592003000200001
Abstract: this work proposes a genetic algorithm (ga) to solve process estimation problems when the real process presents high orders polynomials (complexity model) or non-linearities, non-minimum phase behavior, etc. the algorithm finds the best linear model in the pole and zero form to represent the real plant using its input and output signals. a new chromosome representation was introduced and a new ''fitness'' function based on the tradeoff bias x variance was developed. to validate this genetic estimator, simulations studies were done and the ga performance was compared with one obtained by use of the traditional least square estimation method.
Identifica o genética de modelos por pólos e zeros baseada no compromisso entre os erros de polariza o e variancia
Arruda L.V.R.,Fávaro Sílvio,Neves-Jr. F.
Sba: Controle & Automa??o Sociedade Brasileira de Automatica , 2003,
Abstract: Este trabalho prop em um algoritmo genético aplicado ao problema de identifica o de plantas n o-lineares, de fase n o-mínima ou plantas lineares de ordem superior. O algoritmo proposto tem como objetivo encontrar um modelo linear na forma de pólos e zeros e de ordem reduzida, que melhor represente a planta real, a partir dos sinais de entrada e saída. Uma proposta inovadora para a representa o dos indivíduos e fun o de ''fitness'' foi desenvolvida neste trabalho. Esta fun o de fitness representa o compromisso entre os erros de polariza o e variancia do modelo estimado. Já a representa o proposta divide o espa o de busca em dois subespa os: um destinado à busca de pólos e zeros de natureza real e outro com a finalidade de se encontrar os pólos e zeros complexos. Resultados de simula o s o utilizados para ilustrar o desempenho do estimador genético desenvolvido.
Inova??o na fabrica??o de cervejas especiais na regi?o de Belo Horizonte
Ferreira, Rubens Hermógenes;Vasconcelos, Maria Celeste R Lobo;Judice, Valéria Maria Martins;Neves, Jorge Tadeu de Ramos;
Perspectivas em Ciência da Informa??o , 2011, DOI: 10.1590/S1413-99362011000400011
Abstract: this article aims to identify the innovation in special beers brewery in belo horizonte's region. in order to do that, concepts as special beers, innovation, entrepreneurship and knowledge sharing have been used. the literature review focused on the evolution of the brewery industry, the innovation process and the different typology used by the traditional authors who are experts on the subject. authors as schumpeter and tidd, bessant & pavitt (2008) have helped with the definition of innovation that was used in this paper. the data was gathered through interviews with special beers manufacturers, observation in sectorial panels, round tables in events and documental research. the researched individuals were the ones involved with special beer as: micro-brewers, homebrewers and consultants. it is concluded that the innovation has been important for those who work with this kind of beer either due to the product differentiation, the need to follow the market demands or due to the incipient participation in social networks in order to share the knowledge. the results of the research show that innovation has been applied in the handmade brewery sector especially in the incremental ones.
Biometria de frutos e sementes e germina??o de Plathymenia reticulata benth. e Plathymenia foliolosa benth. (Fabaceae - mimosoideae)
Lopes, Renata de Melo Ferreira;Freitas, Valéria Lúcia de Oliveira;Lemos Filho, José Pires de;
Revista árvore , 2010, DOI: 10.1590/S0100-67622010000500005
Abstract: this study aimed to compare the biometry of fruits and seeds, as well as the effect of different scarification, temperature and light conditions on the germination of plathymenia reticulata benth. and plathymenia foliolosa benth. we measured the length, width, thickness, and fresh mass of fruits (n= 100) and seeds (n= 100) of each specie. the different treatments were mechanic and acid scarification, temperatures (photoperiod/nictoperiod) of 20, 30 and 35/15 °c (12/12 and 0/24) and 25 and 35 °c (12/12). p. foliolosa fruits were wider, thickener and heavier. its seeds are longer and thicker than those of p. reticulata. seeds of both species were not photosensitive. acid scarification did not increase significantly the percentage of seed germination of both species, but mechanic scarification increased significantly the percentage of seed germination for p. foliolosa. the percentage of germination at 25 °c of intact seeds of p. reticulata, scarified with acid and with sandpaper was, respectively, 55%, 60% and 89%. for seeds of p. foliolosa values obtained were, respectively, 48%, 37.5% and 83%. these results indicate limitations of germination of p. foliolosa imposed by the tegument but the effect of tegument restringing the germination of intact seeds decrease with the increase of temperature.
Caso para diagnóstico
Silveira, Kleber de Sousa;Zac, Renata Indelicato;Oliveira, Patrícia Jannuzzi Vieira e;Neves, Daniela Rezende;Barbosa, Valéria Gomes;Café, Maria Ester Massara;
Anais Brasileiros de Dermatologia , 2009, DOI: 10.1590/S0365-05962009000600018
Abstract: the case of a 9-year-old girl with a history of blistering lesions restricted to the right side of her body is described. several family members are also affected in a symmetrical fashion. histological examination showed acantholysis similar to a "dilapidated brick wall", corresponding to a rare presentation of mosaicism in hailey-hailey disease.
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