Compactação do solo e intervalo hídrico ótimo no crescimento da parte aérea e produtividade da cultura do milho

The aim of this work was to evaluate the effect of soil compaction caused by tractor wheel traffic on the limiting water range (LLWR), shoot growth and levels of compaction and four replications in a completely randomized experimental design. Soil samples with preserved structure were collected in the layers: 0.02-0.05; 0.08-0.11; 0.15-0.18 and 0.22-0.25m to determine macroporosity, microporosity, total porosity, bulk density, resistance to penetration and LLWR. The evaluated corn parameters were: plant and first spike height, steam diameter, number of spikes per plant, plant dry matter, dry matter of 1000 seeds and seed productivity. The soil compaction restricted all corn parameters except the number of spikes per plant and dry matter of 1000 seeds. The LLWR was reduced by the soil resistance to penetration, even in the tilled soil with bulk density of 1.12 Mg m-3. Only the treatment with 11 Mg tractor, repeated four times on the area, demonstrated bulk density above critical bulk density in the LLWR that was 1.37 Mg m-3, where the seed productivity was significantly smaller.

A resolução do problema de despacho ótimo de reativos pelo método da função Lagrangiana-barreira relaxada

This work presents the application of the relaxed barrier-Lagrangian function method to the optimal reactive dispatch problem, which is a nonlinear nonconvex and large problem. In this approach the inequality constraints are treated by the association of modified barrier and primal-dual logarithmic barrier method. Those constraints are transformed in equalities through positive auxiliary variables and are perturbed by the barrier parameter. A Lagrangian function is associated to the modified problem. The first-order necessary conditions are applied generating a non-linear system which is solved by Newton's method. The auxiliary variables perturbation result in an expansion of the feasible set of the original problem, allowing the limits of the inequality constraints to be reach. Numeric tests with the systems CESP 53 buses and the south-southeast Brazilian and the comparative test with the primal-dual logarithmic barrier method indicate that presented method is efficient in the resolution of optimal reactive dispatch problem.

Estudio económico de América Latina 1970 = Economic survey of Latin America 1970

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Estudio económico de América Latina 1977 = Economic survey of Latin America 1977

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Estudio económico de América Latina 1980 = Economic survey of Latin America 1980

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Estudio económico de América Latina 1981 = Economic survey of Latin America 1981

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Estudio económico de América Latina y el Caribe 1982 = Economic survey of Latin America and the Caribbean 1982

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Estudio económico de América Latina y el Caribe 1983 = Economic survey of Latin America and the Caribbean 1983

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Estudio económico de América Latina y el Caribe 1984 = Economic survey of Latin America and the Caribbean 1984

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Estudio económico de América Latina y el Caribe 1985 = Economic survey of Latin America and the Caribbean 1985

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Estudio económico de América Latina 1948 = Economic survey of Latin America 1948

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Estudio económico de América Latina 1949 = Economic survey of Latin America 1949

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Estudio económico de América Latina 1950 = Economic survey of Latin America 1950 = Etude economique de l'Amerique Latine pour 1950

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Estudio económico de América Latina 1979 = Economic survey of Latin America 1979

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Estudio económico de América Latina 1951-1952 = Economic survey of Latin America 1951-1952

Estudio presentado en forma preliminar al Quinto Período de Sesiones de CEPAL, Río de Janeiro, 1953