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991.
In order to improve operation for shortening tap to tap time and saving electrical energy, on the base of no-linear reactance model, the electrical characteristics of the 50 t UHP-EAF in Fushun Special Steel Co. Ltd. were analyzed. Considering steelmaking process conditions, the optimum power-input diagrams were investigated, which can save energy, lower consumption, and raise productivity. This has been verified by production contrast tests. Application of the optimum curve in 50 t UHP-EAF indicates that research method is correct, the 50 t UHP-EAF runs smoothly with lowering electrical energy by 29.35 kW.h/t and shortening power on time by 3 rain. The general steps of making optimum power-input specification is also given. 相似文献
992.
JIANGHong-yi LONGHai-shan ZHANGLian-meng 《武汉理工大学学报(材料科学英文版)》2004,19(2):55-56
The Mg2 Si-matrix thermoelectric material was stnthesized by low temperature solid-state renc-tion.This paper studies the effects of holding time and reaction temperatare on the particle size and the properties of the material, and also studies effects of doping elemental Sb, Te and their doping seqence on the properties of the materiol. The result shows that excessirely high temperature and elongated holding time of solid-state reaction are harmful, there is a range of partiele size to ensure optimum properties and the doping sequence of Sb or Te without influencing the properties. 相似文献
993.
高校学生公寓是学生学习、生活的重要场所,引导学生养成良好的行为习惯有助于学生公寓管理工作的顺利开展。文章从维护高校稳定、增强大学生的法律意识和法制观念、促进大学生自我发展、实现学生公寓“管理”、“育人”职能等方面论述学生行为习惯养成的重要性,并从制度建设、环境教育、文化熏陶、组织保障等方面提出具体对策措施。 相似文献
994.
We consider the parallel machine scheduling problem of minimizing the sum of quadratic job completion times. We first prove that the problem is strongly NP-hard. We then demonstrate by probabilistic analysis that the shortest processing time rule solves the problem asymptotically. The relative error of the rule converges in probability to zero under the assumption that the job processing times are independent random variables uniformly distributed in (0, 1). We finally provide some computational results, which show that the rule is effective in solving the problem in practice. 相似文献
995.
Zhihua Xu Yongxiang Li Zhifu Liu Zhi Xiong 《Materials Science and Engineering: B》2004,110(3):302-306
The synthesis of trivalent terbium doped ZnGa2O4 nanosized new phosphors by the Pechini method was reported. Well-crystallized ZnGa2O4:Tb3+ phosphors were obtained at low-temperature about 550 °C. The phosphors formed porous agglomerates which consist of spherical nanocrystallites with a uniform size at about 30 nm. The photoluminescence of the phosphors included both the luminescence of ZnGa2O4 host and characteristic emission of Tb3+, and the excitation spectra showed an energy transfer from the host lattice to the activator. The Tb3+ emission from the phosphors prepared by the Pechini process was more intensive than that of phosphors by solid-state reaction process. 相似文献
996.
Continuous cast (CC) AA5182 Al alloy with the precipitation of Mg2Al3 and of MnAl6 was cold rolled to 70% reduction and then isothermally annealed in a salt bath at three temperatures (316, 343, and 371 °C) for different times. Texture evolution during recrystallization was investigated. It was found that the recrystallization textures of the material with intense Mg2Al3 precipitation along the grain boundaries exhibited weaker Cube, Goss and R/β fiber components than those of the material with the more uniform fine MnAl6 precipitates. The opposite was true in the cold rolled condition, i.e. the material with MnAl6 precipitation had weaker Cube, Goss, and R/β fiber components in the cold rolled condition than the material with intense Mg2Al3 precipitation. Thus, recrystallization textures of material with Mg2Al3 precipitation were weaker than material with MnAl6 precipitation. This is due to the fact that large Mg2Al3 particles favor the nucleation of randomly oriented grains. When subjected to formability tests, the material with prior Mg2Al3 precipitation displayed a lower anisotropy in tensile yield strength, ultimate tensile strength, elongation, and strain hardening exponent than material with prior MnAl6 precipitation. This is in accord with the texture results which indicated that the recrystallization textures of material with an initial Mg2Al3 precipitation were closer to those of a perfectly random sample than those of material with an initial MnAl6 precipitation. On the other hand, the elongation and Olsen values were lower and the surface quality after bending tests was worse for material with Mg2Al3 precipitation. This is due to the non-uniform distribution of Mg2Al3 particles which precipitated primarily along the grain boundaries and caused an earlier formation and coalescence of the microvoids around the grain boundary precipitates. The forming limit diagrams (FLD) correlated well with the tensile, Olsen and bending results. 相似文献
997.
998.
B. V. Alekhin A. E. Dubinov V. S. Zhdanov V. G Kornilov K. E. Mikheev V. D. Selemir N. V. Stepanov V. I. Chelpanov O. A. Shamro 《High Temperature》2004,42(6):851-857
A method of producing compact long-lived plasma formations (plasmoids) is described. The method is based on the effect of capture of a high-current relativistic electron beam under conditions of significant overcompensation of space charge of the beam by positive background ions. Requirements are formulated which are placed on the parameters of a plasma-beam system for the realization of this method, and numerical estimates are given of the overall electric charge and energy content of the electron component of a plasmoid. The dynamics of forming a plasmoid are investigated experimentally.Translated from Teplofizika Vysokikh Temperatur, Vol. 42, No. 6, 2004, pp. 843–849.Original Russian Text Copyright © 2004 by B. V. Alekhin, A. E. Dubinov, V. S. Zhdanov, V. G Kornilov, K. E. Mikheev, V. D. Selemir, N. V. Stepanov, V. I. Chelpanov, and O. A. Shamro. 相似文献
999.
Rajib Kumar Bhattacharjya 《Sadhana》2004,29(5):499-508
A nonlinear optimization model is developed to transmute a unit hydrograph into a probability distribution function (PDF).
The objective function is to minimize the sum of the square of the deviation between predicted and actual direct runoff hydrograph
of a watershed. The predicted runoff hydrograph is estimated by using a PDF. In a unit hydrograph, the depth of rainfall excess
must be unity and the ordinates must be positive. Incorporation of a PDF ensures that the depth of rainfall excess for the
unit hydrograph is unity, and the ordinates are also positive. Unit hydrograph ordinates are in terms of intensity of rainfall
excess on a discharge per unit catchment area basis, the unit area thus representing the unit rainfall excess. The proposed
method does not have any constraint. The nonlinear optimization formulation is solved using binary-coded genetic algorithms.
The number of variables to be estimated by optimization is the same as the number of probability distribution parameters;
gamma and log-normal probability distributions are used. The existing nonlinear programming model for obtaining optimal unit
hydrograph has also been solved using genetic algorithms, where the constrained nonlinear optimization problem is converted
to an unconstrained problem using penalty parameter approach. The results obtained are compared with those obtained by the
earlier LP model and are fairly similar. 相似文献
1000.