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Search Results: 1 - 10 of 36992 matches for " Marcos Roberto;Silveira "
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Problema H2/H: solu??es aproximadas por meio de expans?o em bases
Ades, Roberto;Silveira, Marcos Azevedo da;
Sba: Controle & Automa??o Sociedade Brasileira de Automatica , 2002, DOI: 10.1590/S0103-17592002000300001
Abstract: this paper presents a tutorial on the mixed h2/h¥ control problem. it is formulated from the usual problems in the control theory and servomechanisms, showing the existence, uniqueness and regularity conditions of its solutions. besides, a direct method for approach its solution is showed with a certain detail, based on expansions of redundant generating sets and with the support of a dual method existent in the literature. the finite dimension resultant optimization problems are convex, demanding a subgradient associated to the h¥ restriction. it seems non affect the numeric efficiency of the proposed algorithm, as it can be seen in some examples.
Problema H2/H¥: solu es aproximadas por meio de expans o em bases
Ades Roberto,Silveira Marcos Azevedo da
Sba: Controle & Automa??o Sociedade Brasileira de Automatica , 2002,
Abstract: Neste artigo apresenta-se um tutorial sobre o Problema de Controle ótimo H2/H¥, formulando-o a partir dos problemas usuais da Teoria de Controle e Servomecanismos, mostrando as condi es de existência, unicidade e regularidade de suas solu es. Apresenta-se também, com certo detalhe, um método direto para a aproxima o de sua solu o, baseado em expans es de conjuntos geradores redundantes e em um método dual já existente na literatura. Os problemas de otimiza o aproximantes, convexos e de dimens o finita, exigem o uso de um subgradiente associado à restri o H¥, o que parece n o afetar a eficiência numérica do algoritmo proposto, como é mostrado em alguns exemplos de sua aplica o.
Yield and performance of sugarcane in on-farm interface with rubber in Brazil
Pinto, Luís Fernando Guedes;Bernardes, Marcos Silveira;Pereira, Ant?nio Roberto;
Pesquisa Agropecuária Brasileira , 2006, DOI: 10.1590/S0100-204X2006000200009
Abstract: agroforestry systems are indicated as an alternative for sugarcane (saccharum officinarum) cultivation in piracicaba, sp, brazil, however there are not many field experiments on plant performance under these conditions in the world. the objective of this work was to assess crop yield and partitioning in a sugarcane-rubber (hevea brasiliensis) interface in on-farm conditions. the availability of irradiance for the crop along the interface was simulated and its effe ct over sugarcane dry matter production was tested. crop yield was negatively affected by distance of the trees, but development and sucrose were not affected. above ground dry matter increased from 16.6 to 51.5 t ha-1 from trees. partitioning did not have a defined standard, as harvest index increased from 0.85 to 0.93, but specific leaf area was not significant along the transect, ranging from 13.48 to 15.73 m2 kg-1. light is the main factor of competition between the trees and the crop, but the relative importance of below ground interactions increases closer to the trees. feasibility of the system depends on maturity of the trees and management strategies.
ADUBA??O NPK E PRODU??O DE BORRACHA SECA PELA SERINGUEIRA (Hevea brasiliensis)
Murbach, Marcos Roberto;Boaretto, Antonio Enedi;Muraoka, Takashi;Silveira, Ronaldo Ivan;Boaretto, Rodrigo Marcel;
Scientia Agricola , 1999, DOI: 10.1590/S0103-90161999000100011
Abstract: an experiment was carried out to study the effects of nitrogen, phosphorus and potassium fertilizations on dry rubber yield of hevea brasiliensis muell arg., clone pb 235 growing on a dark red-yellow latosol, in gar?a-sp, brazil. the experiment consisted of a (1/4)43 fractional factorial of randomized block design, with 16 treatments and 4 replicates, utilizing 4 levels of n (0, 80, 160 and 320 kg ha-1), 4 of p2o5 (0, 40, 80 and 160 kg ha-1) and 4 of k (0, 80, 160 and 320 kg ha-1). the rubber yield was evaluated monthly from october 1995 to june 1996. results showed that potassium fertilization increased dry rubber yield, which was not affected by nitrogen and phosphate fertilizations.
Privatiza??o dos servi?os de extens?o rural: uma discuss?o (des)necessária?
Diesel, Vivien;Froehlich, José Marcos;Neumann, Pedro Selvino;Silveira, Paulo Roberto Cardoso da;
Revista de Economia e Sociologia Rural , 2008, DOI: 10.1590/S0103-20032008000400010
Abstract: the article analyzes and discusses the privatization of the rural extension services according to international literature. to start with, the subject is set in the horizon of the debate of the so called state reform, which determined the agenda for the development since the 1980's. next, we show how the subject has been treated so far having the economic theory as background and we examine experiments of privatization at international level. the analysis of such experiments reveals that the early agenda for the privatization took for granted that the rural extension services - which were a responsibility of the state - would be held completely by the private sectors. however, a series of obstacles appeared and arguments for models of privatization in which the state has a main role spread over. therefore, the exam of international experiments of privatization led to the conclusion that they followed different orientations. one set of experiments was oriented by the notion of the "minimum state" while the other had for reference the state as a supporter for private action. the privatization is a current and relevant process and, therefore, the discussion about it is considered necessary.
Angiopatia amilóide cerebral simulando tumor cerebral: relato de caso
Andrade Gustavo Cardoso de,Silveira Roberto Leal,Pinheiro Jr. Nilson,Rocha Eckstanio Marcos Melo
Arquivos de Neuro-Psiquiatria , 2006,
Abstract: Descrevemos o raro caso de um paciente de 45 anos portador de les o expansiva intracraniana por angiopatia amilóide cerebral com características clínicas e de imagem compatíveis com um glioma de baixo grau. A biópsia revelou angiopatia amilóide cerebral. Os achados clínicos, radiológicos e histopatológicos s o discutidos e analisados juntamente à literatura disponível.
ADUBA O NPK E PRODU O DE BORRACHA SECA PELA SERINGUEIRA (Hevea brasiliensis)
Murbach Marcos Roberto,Boaretto Antonio Enedi,Muraoka Takashi,Silveira Ronaldo Ivan
Scientia Agricola , 1999,
Abstract: Instalou-se um experimento, na regi o de Gar a, SP, em um solo Latossolo Vermelho escuro, A moderado, textura arenosa, com o objetivo de se avaliar a influência da aduba o NPK sobre a produtividade de borracha seca da seringueira (Hevea brasiliensis) clone "PB 235", com 13 anos de idade. O experimento foi instalado em blocos ao acaso, em esquema fatorial fracionário (1/4)43, totalizando 16 tratamentos e 4 repeti es, onde se utilizaram 4 níveis de N (0, 80, 160, 320 kg ha-1), 4 de K2O (0, 80, 160, 320 kg ha-1) e 4 de P2O5 (0, 40, 80, 160 kg ha-1). A produ o foi avaliada entre os mêses de outubro de 1995 a junho de 1996. Conclui-se que a aduba o potássica aumentou a produtividade de borracha seca, o mesmo n o ocorrendo com a aduba o nitrogenada e fosfatada.
APORTE DE NUTRIENTES E BIOMASSA VIA SERRAPILHEIRA EM SISTEMAS AGROFLORESTAIS EM PARATY (RJ)
Nina Duarte Silveira,Marcos Gervasio Pereira,José Carlos Polidoro,Sílvio Roberto de Lucena Tavares
Ciência Florestal , 2007,
Abstract: O objetivo deste trabalho foi avaliar a sustentabilidade ambiental de Sistemas Agroflorestais Regenerativos e Análogos (Safra), utilizando-se como indicadores de sustentabilidade ambiental o aporte de biomassa e nutrientes via serrapilheira de espécies arbóreas plantadas. Este trabalho faz parte das a es do PRODETAB – projeto 039 e foi desenvolvido na Fazenda Goura Vrindávna, Paraty, RJ. Foram plantadas 28 espécies arbóreas de múltiplos usos em três tratamentos agroflorestais, Safra Mínimo (sistema simplificado de enriquecimento de bananal), Safra Absoluto (sistema adensado e diversificado) e Safra Modificado (mesma composi o do anterior e com aduba o do solo). Para a avalia o do aporte de nutrientes via serrapilheira; foram coletadas amostras nos três tratamentos Safras e em dois tratamentos testemunhas (Bananal e Capoeira) por meio de coletores de 625 cm2, 15 meses após o plantio. Nas amostras, foram feitas as determina es dos teores e conteúdos de micro e macronutrientes. O Safra Mínimo foi o sistema que depositou maior peso de serrapilheira (32,4 Mg ha-1) e aportou maiores conteúdos de micro e macronutrientes. Com exce o do C e H, o N foi o que apresentou os maiores conteúdos nos cinco tratamentos, e em rela o aos micronutrientes, o Fe foi o elemento de maior aporte. A poda da vegeta o nos Safras favoreceu a ciclagem de nutrientes e contribuiu para eleva o dos conteúdos destes na serrapilheira. Os Safras, sob o aspecto do aporte de nutrientes via serrapilheira, foram os sistemas mais promissores na recomposi o dessas fun es ecológicas, quando comparados à Capoeira e monocultura de banana.
Angiopatia amilóide cerebral simulando tumor cerebral: relato de caso
Andrade, Gustavo Cardoso de;Silveira, Roberto Leal;Pinheiro Jr., Nilson;Rocha, Eckstanio Marcos Melo;Pittella, José Eymard Homem;
Arquivos de Neuro-Psiquiatria , 2006, DOI: 10.1590/S0004-282X2006000100034
Abstract: we describe the unusual case of a 45-year-old male patient harboring an intracranial mass due to cerebral amyloid angiopathy whose clinical and radiological features were those of a low grade glioma. biopsy revealed cerebral amyloid angiopathy. the clinical, radiological and pathological findings are discussed as we review the available literature.
Laminoplastia expansiva: uma alternativa no tratamento da mielopatia espondilótica cervical
Andrade, Gustavo Cardoso de;Silveira, Roberto Leal da;Arantes Jr, Aluízio Augusto;Pinheiro Jr, Nilson;Melo Rocha, Eckstanio Marcos;
Arquivos de Neuro-Psiquiatria , 2005, DOI: 10.1590/S0004-282X2005000600018
Abstract: we describe the surgical technique of expansive cervical laminoplasty and analyse the results in 28 patients treated by this method for cervical spondylotic myelopathy with a minimum follow-up of six months. twenty-four patients (86%) had clinical improvement according to the nurick scale while three (10%) had no improvement and one patient died on the first days post-operatively. the good results achieved demonstrate that this technique is simple, effective and has few complications on the treatment of spondylotic myelopathy.
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