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The characteristics of arc beam shaping in hybrid plasma and laser deposition manufacturing

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Science china(Technological Sciences) 2006年第2期49卷 238-247页

作者： ZHANG Hai’ou1, QIAN Yingping1,3, WANG Guilan1 & ZHENG Qiguang2 1. school of Material Science and technology, huazhong university of Science and technology, wuhan 430074, china 2. Institute of Laser technology and Engineering, huazhong university of Science and technology, wuhan 430074, china 3. Mechanical Engineering College, hubei university of technology, wuhan 430068, china 1. school of Material Science and technology Huazhong University of Science and Technology Wuhan 430074 China 3. Mechanical Engineering College Hubei University of Technology Wuhan 430068 China 2. Institute of Laser technology and Engineering Huazhong University of Science and Technology Wuhan 430074 China

As a new direct metal prototyping technology,the hybrid plasma and laser deposition manufacturing (PLDM) is proposed in this paper. In order to figure out the characteristics of plasma arc beam and mould in the PLDM process of high temperature alloy, the high speed CCD camera is used to obtain the picture around the plasma arc. Afterwards the sketch of picture is clearly obtained. And the effect of laser parameter, such as average power, pulse width, pulse repetition frequency and the angle between laser beam and plasma arc beam on the plasma arc appearance, is studied experimentally. The results show that the modality of plasma arc beam is markedly influenced by laser beam. And the improvements of shape precision and surface state of the layer deposited by PLDM are confirmed.

关键词： plasma hybrid laser, direct deposition, plasma arc beam, molding character, high-temperature alloy.

Quasi-physical global optimization method for solving the equal circle packing problem

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Science china(Information Sciences) 2011年第7期54卷 1333-1339页

作者： HUANG WenQi & YE Tao school of Computer Science and technology,huazhong university of Science and technology,wuhan 430074,china 1. school of Computer Science and technology Huazhong University of Science and Technology Wuhan 430074 China

The equal circle packing problem is a well-known challenge in *** is also a natural,clear and fair test system for global *** paper presents a quasi-physical global optimization algorithm for solving the equal circle packing *** algorithm simulates two kinds of movements of N elastic disks: smooth movement driven by elastic pressures and violent movement driven by strong repulsive forces and attractive *** smooth movement makes the disks reach a locally optimal configuration,while the violent movement makes them jump out of the local optimum trap and reach a more promising *** algorithm is tested on the widely studied instances of N = 1,2,...,*** find better packings than the reported best-known ones on 37 instances and reproduce the best-known results on the remaining 113 instances.

关键词： equal circle packing global optimization quasi-physical method heuristic

A quasi-human algorithm for solving the three-dimensional rectangular packing problem

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Science china(Information Sciences) 2010年第12期53卷 2389-2398页

作者： HE Kun & HUANG WenQi school of Computer Science and technology, huazhong university of Science and technology, wuhan 430074, china 1. school of Computer Science and technology Huazhong University of Science and Technology Wuhan 430074 China

Based on the concept of maximal rectangular space that can be filled at current time and the siege warfare tactics, we make several critical improvements on the quasi-human caving-degree approach to get a stronger algorithm ICDA for a classical NP hard problem: the three-dimensional rectangular packing problem. Within similar computing time, the new algorithm gained an average volume utilization of 90.92% on the natural and difficult 100 benchmarks, called BR15, where items to be packed are almost different in size. Compared with current best record just reported in the literature in 2010, our result makes an improvement by 0.54%.

关键词： NP hard three-dimensional packing quasi-human action space caving degree

AGGLOMERATION AND RADIATION EFFECT OF THE PULL OF URBANIZATION

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Chinese Geographical Science 2003年第3期13卷 224-227页

作者： QI Jin-li (school of Economics, huazhong university of Science and technology, wuhan 430074, P. R. china) school of Economics Huazhong University of Science and Technology Wuhan 430074 P. R. China

In order to explore the train of thought for china’s urbanizing development and coordinated rural economic development, and to find good ways of solving rural problems through urbanization, this paper absorbs the push-and-pull forces theory and the systematic dynamic theory in the traditional population migration theories, views urbanization as a dynamic system, makes research on the push-and-pull mechanism of urbanization. The pulling power of urbanization is analyzed according to two aspects, the agglomeration effect and the radiation effect of cities. The agglomeration effect provides continuous propelling force for urbanization, and the radiation effect further accelerates the urbanization process by pushing forward the development of rural economy. Of course, the slow development of urbanization can result in the hindrance to rural economic development.

关键词： agglomeration effect radiation effect pull of urbanization

METHOD TO SOLVE ELASTIC CONJUGATE SURFACES IN MULTI-TEETH MESHING

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Chinese Journal of Mechanical Engineering 2002年第4期15卷 348-352页

作者： Yi Chuanyunschool of Mechanical Science and Engineering, huazhong university of Science and technology,wuhan 430074, china school of Mechanical Science and Engineering Huazhong University of Science and Technology Wuhan 430074

A method to solve the elastic conjugate surfaces in multi-teeth meshing ispresented. In mechanical manufacturing and design, there exist a lot of problems relating toconjugate surfaces, such as three-dimensional engagement, steel rolling and workpiece machining,which cause great effects on the quality of machining and performances of transmission. This methoddescribes relation between conjugate motion and elastic deformation in the process of mesh-in andmesh-out, and can be used to determine the profile of gear tooth by a certain given load sharing.

关键词： multi-teeth meshing elastic conjugate surfaces

NOVEL FORMULATION OF STATIC STABILITY FOR A WALKING QUADRUPED ROBOT

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Chinese Journal of Mechanical Engineering 2003年第2期16卷 120-122页

作者： Chen Xuedongschool of Mechanical Scienceand Engineering,huazhong university of Scienceand technology,wuhan 430074, china school of Mechanical Science and Engineering Huazhong University of Science and Technology Wuhan 430074 China

By defining the static stable area for foot placement, a new approach toanalysis of quadruped robot stability is presented. Unlike conventionally, the method avoids solvingcomplicated direct kinematics of quadruped robot and shows the information on the robot stabilityand the selection of swing leg. Especially, the proposed algorithm can be used as real-timeoperation for on-line gait generation and control for quadruped robots. The effectiveness of theproposed approach is shown through a practical crawling experiment of the quadruped robotTITAN-VIII.

关键词： quadruped robot static stability gait generation

YIELD CRITERION IN PLASTIC-DAMAGE MODELS FOR CONCRETE

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Acta Mechanica Solida Sinica 2010年第3期23卷 220-230页

作者： Ji Zhang Zhongxian Zhang~★Chuanyao Chen (school of Civil Engineering and Mechanics,huazhong university of Science and technology, wuhan 430074,china) [a] school of Civil Engineering Mechanics Huazhong University of Science technology Wuhan 430074 China

A class of plastic-damage models for concrete require an unambiguous definition of cohesion in the yield criteria. For this reason, the Lubliner yield criterion has been adopted by many investigators and the commercial FE program Abaqus. As is well known, this criterion has achieved great success especially in plane stress states. In this paper, we are trying to extend it to triaxial compression stress states. First, a major limitation of the Lubliner criterion is analyzed. Then, a revised version of the Lubliner criterion is proposed, which shows appropriate properties over a wide range of stress states often encountered in engineering structures, and the predicted failure envelopes fit well with experimental data. For the concrete damaged plasticity model in Abaqus, a calibration strategy is suggested for uniformly confined concrete.

关键词： plastic-damage model Lubliner yield criterion triaxial compression concrete damaged plasticity

Computationally efficient channel estimation and inter-carrier interference suppression for OFDM communication systems

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The Journal of china Universities of Posts and Telecommunications 2009年第6期16卷 17-23页

作者： CAI Meng,ZHANG Ke-feng,ZOU Xue-cheng,LIU Hao school of Electronics of Science and technology,huazhong university of Science and technology,wuhan 430074,china [a] school of Electronics of Science and technology huazhong university of Science and technology wuhan 430074 china

This article puts forward a novel channel estimation and inter-carrier interference（ICI） suppression method for time-varying orthogonal frequency division multiplexing（OFDM） *** proposed adaptive finite impulse response（FIR） filter utilizes the time domain correlation of the *** on the one order auto-regressive（AR） model,a modified Kalman filter is exploited to track the channel *** solving the Yule-Walker equation,the coefficient of the AR process can be obtained from zero order Bessel ***,when the channel is assumed not perfectly known,the above criterion will lead to an impractical *** deal with it,the coefficient of the AR process is taken as a *** a new state space model is deduced and *** results show that the proposed method can work effectively at the speed of 144 km/h with a phase noise of -85 dBc/Hz at 100 kHz *** proposed method yields an improvement bit error rate（BER） compared with three of the existing algorithms with much lower complexity.

关键词： channel estimation OFDM ICI phase noise Kalman filter

Numerical simulations and experimental investigations on transverse effects of two-wave mixing in a photovoltaic photorefractive crystal

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Science china(Physics,Mechanics & Astronomy) 2010年第5期53卷 856-863页

作者： CAI Xin1,2,LIU JinSong1 & WANG ShengLie1 1 wuhan National Laboratory for Optoelectronics,school of Optoelectronic Science and Engineering,huazhong university of Science and technology,wuhan 430074,china 2 school of Science,wuhan university of technology,wuhan 430070,china 1. wuhan National Laboratory for Optoelectronics School of Optoelectronic Science and Engineering Huazhong University of Science and Technology Wuhan 430074 China2. School of Science Wuhan University of Technology Wuhan 430070 China

The transverse effects of two Gauss waves mixing in a photovoltaic photorefractive crystal,i.e.,the dynamical evolutions of signal beam with different parameters,are traced numerically and *** the one-dimensional numerical simulations and two-dimensional experimental investigations show that the self-focusing effect of signal beam becomes more obvious as the intensity of pump beam and the angle between the signal and pump beams *** accordance with these results,the state of two Gaussian waves mixing is controllable.

关键词： numerical simulation experimental investigation two-wave mixing transverse effects Gaussian distribution