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J.C. Li B.F. Wang J.Z. Cui 《金属学报(英文版)》2007,20(3):157-166
With the aid of ANSYS software, the effect of different mould external part materials on magnetic flux density in the aluminum melt and magnetic field interaction of four coils applied with same currents were investigated. Calculating results showed that magnetic flux density in the aluminum melt was greatly improved and the magnetic field interaction among different coils was decreased when external part of mould is made of soft magnetic material. Based on the finding, a four-strand low-frequency electromagnetic casting 6063 aluminum alloy experiment was carried out in the laboratory. The experiment showed that the surface of the billet was smooth and had no exudations and cold shuts, the as-cast microstructures were fine, uniform, equiaxed, net-globular or globular under low-frequency electromagnetic field. The microstructure becomes finer with increased current value. 相似文献
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AbstractThe RA research reactor is located at the Vin?a Institute of Nuclear Sciences near Belgrade, Serbia. The reactor is a 6·5 MW, tank-type, heavy water moderated and cooled reactor of Russian design which commenced operation in 1959. After being temporarily shut down in 1984 for refurbishment, a final shutdown decision was made in 2002. Operations are underway to safely remove and repatriate the spent nuclear fuel (SNF) to the Russian Federation (RF), as well as to improve waste management throughout the Vin?a site and prepare a plan for reactor decommissioning. As a major activity within the Vin?a Institute Nuclear Decommissioning (VIND) Programme, the repatriation of over 8000 SNF elements containing 2·5 tons of uranium metal will significantly reduce nuclear proliferation and environmental safety risks confronting the current facility. Poor water quality in the SNF storage basins and degraded fuel integrity significantly challenge efforts to repackage and transport the SNF. This paper will focus on the activities related to SNF repackaging and shipment, report on progress, detail significant challenges and provide an overview of the fully integrated VIND project. 相似文献
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Successful psychotherapy with adolescent delinquent boys revealed significant improvement in the perception of interpersonal relationships on thematic stories to pictures selected to measure 3 areas of personality functioning (self-image, control of aggression, and attitude toward authority). People in the stories were seen as having more highly differentiated roles and relationships. These changes were highly correlated with improved academic performance (revealed on achievement tests) and improvement in overt behavior (reduction in antisocial behavior and better employment history). The results are consistent with many views regarding the nature of personality change in psychotherapy and strongly indicate that improvement in the perception of interpersonal relationships is associated with higher levels of overall performance and integration. Exactly how these changes are brought about during psychotherapy still remains to be explored. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
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HU Xiaodong ZHOU Yiqi FANG Jianhua School of Mechanical Engineering Shandong University Jinan China MAN Xiliang Shandong Construction Machinery Group Co.Ltd Jinan China ZHAO Zhengxu School of Computing Derby University Derby DE GB UK 《机械工程学报(英文版)》2007,20(2):88-93
The pressure loss of cross-flow perforated muffler has been computed with the procedure of physical modeling,simulation and data processing. Three-dimensional computational fluid dynam-ics (CFD) has been used to investigate the relations of porosities,flow velocity and diameter of the holes with the pressure loss. Accordingly,some preliminary results have been obtained that pressure loss increases with porosity descent as nearly a hyperbolic trend,rising flow velocity of the input makes the pressure loss increasing with parabola trend,diameter of holes affects little about pressure loss of the muffler. Otherwise,the holes on the perforated pipes make the air flow gently and meanly,which decreases the air impact to the wall and pipes in the muffler. A practical perforated muffler is used to illustrate the available of this method for pressure loss computation,and the comparison shows that the computation results with the method of CFD has reference value for muffler design. 相似文献
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EXPERIMENTAL RESEARCH AND DESIGN ON HEAT TRANSFER OF EVAPORATOR USED IN THE LARGE QUICK FREEZE PLANT
ZHENG Chuanxiang ZHUO Chuanmin 《机械工程学报(英文版)》2007,20(6):18-23
The evaporator is the main part of a quick-freeze equipment. There are many factors influencing the heat transfer coefficient of an evaporator. The most important factors among them are the fin shape, tube diameter, distance of fin space, frost, and velocity of air flow etc. They mainly influence the thermal efficiency of an evaporator, and therefore its thermal efficiency has direct relationship with the whole efficiency of the quick freeze plant. Evaporators with different structural types have different heat transfer efficiency. In order to obtain high efficiency structure of evaporator, 8 evaporator models with different fin shape, tube diameter and tube arrangement are analyzed and compared. The calculation results show that the integral waved fins, equilateral-triangle arranged small diameter tubes and varying fin-spacing has the highest heat transfer coefficient. The experimental result also shows that the evaporator with this type of structure has better thermal efficiency. The experimental result is in good agreement with the calculation result. It can instruct engineering design for usual designer. A real quick-freeze equipment is designed and put into production. The result shows that, compared with traditional domestic quick-freeze equipments, this equipment decreases by 40% in size and by 20% in energy consumption. 相似文献
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EXPERIMENTAL AND NUMERICAL RESEARCH ON BULLDOZER WORKING PROCESS 总被引:1,自引:0,他引:1
A simulative analysis coupled with experiment on behaviors of a soil bed cut by a model bulldozer blade is carried out using the finite element/distinct element method(FE/DEM) facility built in the ELFEN package. Before simulation,the soil specimens are examined through uniaxial tensile/compression,triaxial compression and direct shear tests to obtain model characteristics and relevant parameters,then soil cutting experiments are carried out via a mini-soil bin system with a soil bed of 60/120 mm in width and 10 mm in depth cut by a 1/9 scale model bulldozer blade moving with the velocity of 10 mm/s. The soil constitutive model includes the tensile elastic model for tensile breakage and the compressive elastoplastic relationship with Mohr-Coulomb criterion. The cutting length in simulation is set as 1/4 of that in the experiment divided into 1 869 triangular elements. The comparison between the simulated results and experimental ones shows that the used model is capable of analyzing soil dynamic behaviors qualitatively,and the predicted fracturing profiles in general conform to the experiment. Hence the feasibility for analyzing soil fracturing behaviors in tillage or other similar processes is validated. 相似文献