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Search Results: 1 - 10 of 487964 matches for " Francisco A.;Gomes "
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 Computational & Applied Mathematics , 2007, DOI: 10.1590/S0101-82052007000300003 Abstract: a sequential quadratic programming algorithm for solving nonlinear programming problems is presented. the new feature of the algorithm is related to the definition of the merit function. instead of using one penalty parameter per iteration and increasing it as the algorithm progresses, we suggest that a new point is to be accepted if it stays sufficiently below the piecewise linear function defined by some previous iterates on the (f,||c||22)-space. therefore, the penalty parameter is allowed to decrease between successive iterations. besides, one need not to decide how to update the penalty parameter. this approach resembles the filter method introduced by fletcher and leyffer [math. program., 91 (2001), pp. 239-269], but it is less tolerant since a merit function is still used. numerical comparison with standard methods shows that this strategy is promising.
 Francisco A.M. Gomes Computational and Applied Mathematics , 2007, Abstract: A sequential quadratic programming algorithm for solving nonlinear programming problems is presented. The new feature of the algorithm is related to the definition of the merit function. Instead of using one penalty parameter per iteration and increasing it as the algorithm progresses, we suggest that a new point is to be accepted if it stays sufficiently below the piecewise linear function defined by some previous iterates on the (f,||C||22)-space. Therefore, the penalty parameter is allowed to decrease between successive iterations. Besides, one need not to decide how to update the penalty parameter. This approach resembles the filter method introduced by Fletcher and Leyffer [Math. Program., 91 (2001), pp. 239-269], but it is less tolerant since a merit function is still used. Numerical comparison with standard methods shows that this strategy is promising.
 Computational & Applied Mathematics , 2011, DOI: 10.1590/S1807-03022011000100004 Abstract: we introduce a globally convergent sequential linear programming method for nonlinear programming. the algorithm is applied to the solution of classic topology optimization problems, as well as to the design of compliantmechanisms. the numerical results suggest that the new algorithm is faster than the globally convergent version of the method of moving asymptotes, a popular method for mechanical engineering applications proposed by svanberg.
 Computational & Applied Mathematics , 2011, DOI: 10.1590/S1807-03022011000100006 Abstract: we formulate a truss topology optimization problem as a bilevel programming problem and solve it by means of a line search type inexact restoration algorithm. we discuss details of the implementation and show results of numerical experiments.
 Anais da Escola Superior de Agricultura Luiz de Queiroz , 1987, DOI: 10.1590/S0071-12761987000200011 Abstract: thirty one experiments, using the corn plants microplot biological techinique, were conducted to study the fertility status of soils representative for the production of coconuts in the state of sergipe. the results obtained allowed for the following conclusions: 1. nitrogen and phosphorus were the nost limiting factors for the growth of the plants. 2. the responses to omiting potassium, calcium, magnesium, sulfur and micronutrients showed great variation in the different areas studied, indicating the need for greater studies. is is likewise indicated the need to study the effect of dolomitic limestone in the equilibrium between cations in order to better characterize the defficiencies of some nutrients.
 Arquivos Brasileiros de Cardiologia , 2007, DOI: 10.1590/S0066-782X2007000400024 Abstract: the anomalous origin of the circumflex artery (cx) is uncommon and presents course variations that might make the coronary artery bypass surgery (cabg) difficult. two patients presenting unstable angina were submitted to coronary angiography that disclosed tri-vessel disease and presence of cx with an anomalous origin and retroaortic course with severe stenosis. both patients underwent cabg with use of bilateral internal thoracic artery (ita) grafts. therefore, cabg with bilateral ita use is feasible in cases of an anomalous origin of the cx artery. however, this finding may constitute an additional technical setback.
 Arquivos Brasileiros de Cardiologia , 2008, DOI: 10.1590/S0066-782X2008000100004 Abstract: background: advances in surgical myocardial revascularization (mr) have introduced additional benefits with the off-pump (op) technique and the use of bilateral internal thoracic artery (ita) grafting. off-pump surgical mr has been associated with improved immediate outcomes and reduced incidence of perioperative complications, and the use of bilateral ita grafts provides increased survival and decreased cardiovascular events in the long term. objective: to present the initial experience with the combined use of these advances in surgical mr. methods: a total of 35 consecutive patients undergoing off-pump mr with bilateral ita grafting were studied; the left ita was directed toward the anterior descending artery and the right ita was anastomosed to the circumflex artery branches. the predominant comorbidities were previous myocardial infarction in 71.4% of the patients, diabetes mellitus in 34.2%, and renal failure in 14.2%. results no patients presented electrocardiographic changes or enzyme elevation in the postoperative period. the number of bypasses per patient ranged from two to four (median of three bypasses/patient). postoperative hospital stay ranged from three to 12 days (mean of 4.7 + 1.7 days). no cases of sternal dehiscence or infection were observed, but one patient suffered a stroke on the fourth postoperative day and died. late follow-up lasted from four to 48 months. no late deaths occurred, 31 patients are asymptomatic, and three have residual angina. conclusion: the combination of these technical advances in surgical myocardial revascularization proved efficient and able to contribute to improved benefits in the long term.
 Revista Brasileira de Engenharia Agrícola e Ambiental , 2011, DOI: 10.1590/S1415-43662011000400006 Abstract: the objective of this work was to evaluate the effect of interaction between salinity and plant spacing on maize (zea mays l.) hybrid ag 1051. a randomized block in a 3 x 2 factorial was used, with three row spacings (0.5, 0.7 and 0.9 m) and two levels of salinity of irrigation water (0.8 and 5.0 ds m-1), with five replications. the variables analyzed were: photosynthesis (a), photosynthetically active radiation (par), plant height, shoot dry mass (sdm), leaf area index (lai), leaf area (la), content of carbohydrate, soluble n-amines, na+ and k+. the rates of net photosynthesis did not differ significantly neither as a result of plant spacings nor the salinity of irrigation water. the par intercepted by the basal leaves of maize was higher in the spacing of 0.9 m, but no difference between stressed and unstressed plants in relation to the radiation intercepted by leaves and photosynthetic rates was observed. although salinity affected the levels of carbohydrates and sodium in leaves, the greatest differences were related to plant spacing and leaf age evaluated. in general, the densification of maize cultivation did not minimize the deleterious effects of salinity on plant growth.