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Search Results: 1 - 10 of 336604 matches for " Sílvio;Neves-Jr. "
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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.
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.
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.
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.
Crescimento e sintomas visuais de deficências de micronutrientes em umbuzeiros
Neves, Orlando Sílvio Caires;Sá, José Roberto de;Carvalho, Janice Guedes de;
Revista Brasileira de Fruticultura , 2004, DOI: 10.1590/S0100-29452004000200030
Abstract: the effect of micronutrient omission on growth and nutritional deficiency symptoms in umbuzeiro seedlings cultivated in nutrient solution was evaluated in this work. the experimental design was completely randomized with four replication and seven treatments, being them: complete (all the nutrients), with individual omission of b, cu, fe, mn and zn and simultaneous omission of zn and cu. the absence of b, cu, fe, mn and zn in the nutrient solution implicated on the reduction plants development inducing morphologic alterations with characteristic symptoms of nutritional deficiency of each nutrient. the umbuzeiro was shown more demanding in b, fe and zn in the initial phase of growth than mn and cu. the reduction in the total dry matter of the umbuzeiro seedlings was influenced in the following order: fe > b > zn > zn+cu > cu > mn.
Crescimento, nutri??o mineral e nível crítico foliar de P em mudas de umbuzeiro, em fun??o da aduba??o fosfatada
Neves, Orlando Sílvio Caíres;Carvalho, Janice Guedes de;Oliveira, Eric Victor de;Neves, Vanessa Brito Fernandes;
Revista Brasileira de Fruticultura , 2008, DOI: 10.1590/S0100-29452008000300040
Abstract: this work was accomplished in order to evaluate the growth, the mineral nutrition and the foliar critical level of p in 'umbuzeiro' seedlings, grown in pots containing distroferric red latosol, in function of phosphorus fertilization. the experimental design was randomized blocks with four replications and six doses of p (0, 30, 60, 120, 240 and 480 mg dm-3). the phosphorus fertilization was done in just one application, before the transplant of the seedlings. the dose of 281 mg dm-3 of p provided the highest production of dry matter of the 'umbuzeiro' seedlings. even when well nourished with p, the 'umbuzeiro' accumulated more organic matter in the root than shoot. the level critical of p in the leaves of the umbuzeiro seedlings range from 1.52 to 1.91 g kg-1.
Crescimento e nutri??o mineral de mudas de umbuzeiro (Spondias tuberosa Arr. Cam.) submetidas a níveis de salinidade em solu??o nutritiva
Neves, Orlando Sílvio Caires;Carvalho, Janice Guedes de;Rodrigues, Carlos Ribeiro;
Ciência e Agrotecnologia , 2004, DOI: 10.1590/S1413-70542004000500005
Abstract: to evaluate the growth and the mineral nutrition of umbuzeiro seedlings, under salt stress, an experiment in nutrient solution was conducted, under greenhouse conditions in the soil science department of the federal university of lavras, brazil. the experimental design was randomized blocs, with four replications and six doses of nacl (0, 20, 40, 60, 80, and 100 mmol l-1). the seedlings were adapted in the hoagland solution to 25, 33 and 50% of ionic forces, staying for fifteen days in each concentration. after this period the seedlings were conduced for 60 days in nutrient solution with 100% of the ionic force and the treatments with nacl. the change of the solutions was made biweekly. the nacl in the nutrient solution affected negatively the growth of the umbuzeiro seedlings. the umbuzeiro was classified as moderately tolerant to salinity when cultivated below 31 mmol l-1 of nacl. the roots compartmentalization is the possible mechanism of tolerance to salt in umbuzeiro seedlings. the order of macronutrient accumulation was: n > k > ca > p > s > mg and n > ca > k > p > s > mg, in the absence and with 100 mmol l-1, respectively and the micronutrient accumulation, except cl, was: fe > b > mn > zn > cu, independent of the concentration of nacl in the solution.
Deficiência nutricional em mudas de umbuzeiro decorrente da omiss?o de macronutrientes
Gon?alves, Francisco César;Neves, Orlando Sílvio Caires;Carvalho, Janice Guedes de;
Pesquisa Agropecuária Brasileira , 2006, DOI: 10.1590/S0100-204X2006000600023
Abstract: the objective of this work was to evaluate the growth and the visual symptoms of macronutrients deficiency in "umbuzeiro" seedlings (spondias tuberosa) cultivated on complete nutritive solution and on solution with individual omission of n, p, k, ca, mg and s. the absences of ca, n, mg and k caused a reduction in seedling growth. the omission of individual macronutrients conducted to morphological disorders related to the nutritional deficiency. a higher requirement of n, k, ca and mg is observed during the initial phase of the growth, and the reduction in total dry matter follows the order: ca > n > k > mg > s > p.
Síntese e caracteriza??o de novos compostos de coordena??o de cobre (II) com ligantes n?o-simétricos N,O-doadores: contribui??es para o sítio ativo da galactose oxidase
Romanowski, Stela Maris de Moraes;Mangrich, Antonio Sálvio;Neves, Ademir;
Química Nova , 2001, DOI: 10.1590/S0100-40422001000500004
Abstract: the reactions of four new unsymmetrical n,o-donor ligands, {h2bbpeten= [n-(2-hydroxybenzyl) - n,n' - bis(2 methylpyridyl) -n'-(hydroxyethyl) ethylenodiamine], h3bpeten=[n,n'- bis(2-hydroxybenzyl) -n- (2-methylpyridyl) -n'- (hydroxyethyl) ethylenodiamine], htpeten=[n,n,n'- tris(2-methylpyridyl) -n'- (hydroxyethyl) ethylenodiamine] and h3bimeten=[n,n'-(2-hydroxybenzyl)-n-(1-methylimidazol-2-il-methyl)-n'- (hydroxyethyl)ethylenodiamine]}, with cu(ii) salts afforded the following mononuclear compounds: [cuii(hbbpeten)]clo4, [cuii(h2bpeten)]clo4 , [cuii(htpeten)](pf6)2 and [cuii(h2bimeten)]clo4 . all were characterized by epr, electronic spectroscopy and electrochemistry. the four copper (ii) compounds showed interesting electrochemistry properties. all presented an anodic wave that can be attributed to the cu (i) oxide formation at the electrode surface, or to a cu0 sediment at the same surface or yet, to cu(i) ? cu(ii) oxidation process with coupled chemistry reaction, due to their irreversibility. two of the complexes are described as interesting synthetic models for the active site of the metalloenzyme galactose oxidase.
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