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Study of Laser Lap Welding of SUS301L Austenitic Stainless Steel Using Optimal Design Method

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稀有金属材料与工程 2011年第S4期40卷 63-67页

作者： Liu Jia,Shi Yan,Zhang Hong school of Electromechanical engineering,changchun university of science and technology,changchun 130022,china changchun Univ Sci & Technol Sch Electromech Engn Changchun 130022 Peoples R China

This paper presents an experimental design approach to process parameter optimization for the laser lap welding of SUS301L austenitic stainless steels using Nd:YAG laser in order to reduce the welding deformations of the back of the welding seams while ensuring mechanical properties of welding *** determine the optimal laser-welding parameters,a set of mathematical models were developed relating welding parameters to each of the weld *** were validated both statistically and *** order to reduce experimental error and the number of specimens,the part of orthogonal experiments were used in this *** quality criteria set for the weld to determine optimal parameters were the maximization of weld width and the minimization of weld *** power,welding speed,the laser irradiation angle,the focused distance and shield gas of 3.5kW,7.0m/min,70°,0mm and N2 with the flow of 30L/min,respectively,with a fiber diameter of 600μm were identified as the optimal set of process parameters.

关键词： laser lap welding sus301l austenitic stainless steel welding deformation orthogonal experiments

A New Genetic Algorithm Based on Niche Technique and Local Search Method

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Journal of university of science and technology Beijing 2001年第1期8卷 63-68页

作者： Jinwu Xu, Jiwen Liu mechanical engineering school, university of science and technology Beijing, Beijing 100083, china Univ Sci & Technol Beijing Sch Mech Engn Beijing 100083 Peoples R China

The genetic algorithm has been widely used in many fields as an easy robust global search and optimization method. In this paper, a new generic algorithm based on niche technique and local search method is presented under the consideration of inadequacies of the simple genetic algorithm. In order to prove the adaptability and validity of the improved genetic algorithm, optimization problems of multimodal functions with equal peaks, unequal peaks and complicated peak distribution are discussed. The simulation results show that compared to other niching methods, this improved genetic algorithm has obvious potential on many respects, such as convergence speed, solution accuracy, ability of global optimization, etc.

关键词： genetic algorithm (GA) niche technique local search method

Prediction and Control of both Wrinkle Limit and Fracture Limiton Cylindrical Cup Deep-drawing(Ⅱ)

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International Journal of Minerals,Metallurgy and Materials 1999年第3期13卷 201-204页

作者： Junxiang Lei Yonglin Kang(Department of mechanical engineering, Yantai university, Yantai 264005, china)(Material science and engineering school, university of science and technology Beijing, Beijing 100083, china) Department of mechanical engineering Yantai University Yantai 264005 China Material science and engineering school University of Science and Technology Beijing Beijing 100083 China

The prediction and control criterion of both the wrinkle limit and fracture limit on the cylindrical cup deep-drawing are given, and the prediction and control diagram of both the wrinkle limit and fracture limit are also given. The results show that it is suitable for no-flange cylindrical cup deep-drawing, narrow-flange cylindrical cup deep-drawing, wide-flange cylindrical cup deep-drawing/expanding compound forming and rigid punch expanding forming.

关键词： cylindrical cup wrinkle limit fracture limit deep-drawing expanding forming compound forming

Change Laws of Flake's Temperature during Making a Diamond Film by DC-PJ

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International Journal of Minerals,Metallurgy and Materials 1999年第2期13卷 97-102页

作者： Xuhong Chen Lihe Zhao Fanxiu Lu(mechanical engineering school, university of science and technology Beijing, Beijing 100083, china) mechanical engineering school University of Science and Technology Beijing Beijing 100083 China

When making a diamond film by direct current plasma jet, a kind piece of flake is used as a base body Which the film can beattached to. The flake's temperature is unstable. Therefore, some experiments and constructed mathematical models, which were solvedby computer, were done. The results show that the flake's temperature is influenced by many factors and the mains are plasma jet powerand vacuum pressure. Through adjusting the two parameters, the flake's temperature can be accurately controlled, furthermore, diamondfilms' quality would be improved. Lowering sediment platform's temperature has a little effect to the flake's temperature at present technology conditions.

关键词： CVD (Chemical Vapor Deposition) plasma, impact heat transfer

Large-eddy simulations and vortex structures of turbulent jets in crossflow

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science china(Physics,Mechanics & Astronomy) 2007年第1期50卷 118-132页

作者： GUAN Hui1,2 & WU ChuiJie2 1 school of mechanical and Power engineering,East china university of science and technology,Shanghai 200237,china 2 Research Center for Fluid Dynamics,PLA university of science and technology,Nanjing 211101,china 1. school of mechanical and Power engineering East China University of Science and Technology Shanghai 200237 China 2. Research Center for Fluid Dynamics PLA University of Science and Technology Nanjing 211101 China

Using the method of large-eddy simulation, the 3-dimensional turbulent jets in crossflow with stream-wise and transverse arrangements of nozzle are simulated, emphasizing on the dynamical process of generation and evolution of vortex structures in these flows. The results show that the basic vortex structures in literatures, such as the counter-rotating vortex pair, leading-edge vortices, lee-side vortices, hanging vortices, kidney vortices and anti-kidney vortices, are not independent physical substances, but local structures of the basic vortex structure of turbulent jets in crossflow-the 3-D stretching vortex rings originating from the orifice of the nozzle, which is discovered in this study. Therefore, the most important large-scale structures of turbulent jets in crossflow are unified to the 3-D vortex rings which stretch and twist in stream-wise and swing in transverse directions. We also found that the shedding frequencies of vortex rings are much lower than the one corresponding to the appearance of leading-edge and lee-side vortices in the turbulent jets.

关键词： turbulent jet in crossflow coherent structure large-eddy simulation

An improved model of Robinson equivalent circuit analytical model

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science china(Technological sciences) 2010年第7期53卷 1993-1999页

作者： MAO XiangYu & DU PingAn school of Mechatronics engineering, university of electronic science and technology of china, Chengdu 611731, china 1. school of Mechatronics engineering University of Electronic Science and Technology of China Chengdu 611731 China

The Robinson equivalent circuit analytical model can be used only in calculating shielding effectiveness of enclosure with the same multi-holes in one wall, but cannot be used in different multi-holes in two walls. According to the practical requirement, this article uses Konefal's and Farhana's characteristic impedance of apertures to improve the equivalent circuit analytical model in different multi-holes in two walls. The improved equivalent circuit analytical model is more useful than Robinson equivalent circuit analytical model. In the article, all kinds of enclosures are simulated by TLM (Transmission-Line Matrix method) to prove that this improved model is feasible in multimode.

关键词： equivalent circuit improved model apertures shielding effectiveness TLM (Transmission-Line Matrix method)

A regularization method in the electromagnetic inverse scattering problem

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Progress in Natural science:Materials International 2007年第3期17卷 346-351页

作者： XIONG Xiaoyun, ZHAO Yanwen and NIE Zaiping (school of electronic engineering, university of electronic science and technology of china, Chengdu 610054, china) [a]school of electronic engineering University of Electronic Science and Technology of China Chengdu China

Based on the normalization of measurement data equations of the inverse scattering problem, a new regularization matrix is proposed. It can eliminate the unfavorable effects caused by difference of distances between field-point or source-point and target region, reduce the loss of useful information in regularization procedure, and decrease condition numbers of the ill-posed problems. Inversion for conductivity distribution of two-dimensional axisymmetric inhomogeneous media is carried out by combing this new regularization method with distorted Born iterative method. Simulation results show that compared with the conventional method, the new regularization method is of better stability, quicker convergence, higher accuracy of inversion and higher resolution.

关键词： inverse scattering regularization distorted Born iterative method.

Nonequilibrium Thermodynamic and Dissipative Structure Mechanism of Fluidized Beds

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International Journal of Minerals,Metallurgy and Materials 1999年第2期13卷 90-93页

作者： Maozhan Qi Li Wang Xuezi Ni (mechanical engineering school, university of science and technology Beijing, Beijing 100083, china) mechanical engineering school University of Science and Technology Beijing Beijing 100083 China

Fluidized beds are nonlinear dynamic systems that exchange mass and energy with outside. They are governed not only byfluid dynamics, but by thermodynamics, especially the second law of thermodynamics as well. According to Prigogine's dissipative structure theory, the following have been concluded: (l) a fixed bed is on thermodynamic blanch, and bubbling, turbulent and fast beds areon the dissipatve structure branches. (2) Entropy in fluidized beds is divided into tWo parts: entropy production and entropy flux. The latter increases with gas velocity and decreases with pressure of the systems. That means the entropy of a system may reduce and the systemwith higher gas velocity behaves as dissipative structure characteristics. (3) For a giVen velocity, a fluidized bed operates stably on thewhole, but it is unstable to local gas-solid phases. The unstable phases are described by fluid dynamic equations, While the minimum ofsystem energy function assures whole stability of the system. (4) A transition criterion of a bubbling bed is derived from Prigogine's stability theory.

关键词： fluidized bed nonequilibrium thermodynamics dissipative structure energy extremum

TRANSMISSION MOMENTARY EFFICIENCY BASED ON THE D'ALEMBERT-LAGRANGE EQUATION FOR INVOLUTES GEARS

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Chinese Journal of mechanical engineering 2004年第2期17卷 272-275页

作者： Liang Yi Lai Changying school of mechanical engineering,Nanjing university of science and technology,Nanjing 210094, china school of mechanical engineering Nanjing University of Science and Technology Nanjing 210094 China Department of science and technology Studies University College London WC1E 6BT UK

The D'Alembert-Lagrange equation is introduced and used to derive theformulas of momentary efficiency for external gearing of standard involutes spur gears. The gearingswith correct and increased center distance are discussed. The momentary efficiency formula iscalculated and analyzed using software Matlab. The derived formula of momentary efficiency is alsocompared with the traditional formula.

关键词： D'Alembert-Lagrange equation Involutes gear Momentary efficiency