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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

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

AN INVESTIGATION OF TURBULENT HEAT TRANSFER IN CHANNEL FLOWS BY LARGE EDDY SIMULATION

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Journal of Hydrodynamics 2002年第2期14卷 29-35页

作者： Dong Yu-hong, Zhong Feng-quan, Lu Xi-yun, Zhuang Li-xian Department of Mechanics and mechanical engineering, university of science and technology of china, Hefei 230026, china Dept. of Mech. and Mech. and Eng. Univ. of Sci. and Technol. of China Hefei 230026 China

Large Eddy Simulation (LES) of fully developed turbulent channel flow with heat transfer was performed to investigate the effects of the Reynolds number on the turbulence behavior. In the present study, the bottom wall of the channel was cooled and the top wall was heated. The Reynolds numbers, based on the central mean-velocity and the half-width of the channel, were chosen as 4000, 6000, 10 4 and 2×10 4, and the Prandtl number as 1.0. To validate our calculations, the present results were compared with available data obtained by Direct Numerical Simulation (DNS), which proves to be in good agreement with each other. To reveal the effects of the Reynolds number, some typical quantities, including the velocity fluctuations, temperature fluctuation, heat fluxes and turbulent Prandtl number, were studied.

关键词： Large Eddy Simulation (LES) turbulent channel flow Subgrid Scale (SGS) model heat transfer stratified turbulence

LEVEL SET METHOD FOR TOPOLOGICAL OPTIMIZATION APPLYING TO STRUCTURE, MECHANISM AND MATERIAL DESIGNS

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Chinese Journal of mechanical engineering 2004年第2期17卷 200-209页

作者： Mei Yulin Wang Xiaoming Department of mechanical engineering,Dalian university of technology,Dalian 116024,china Department of mechanical engineering Dalian University of Technology Dalian 116024

Based on a level set model, a topology optimization method has been suggestedrecently. It uses a level set to express the moving structural boundary, which can flexibly handlecomplex topological changes. By combining vector level set models with gradient projectiontechnology, the level set method for topological optimization is extended to a topologicaloptimization problem with multi-constraints, multi-materials and multi-load cases. Meanwhile, anappropriate nonlinear speed, mapping is established in the tangential space of the activeconstraints for a fast convergence. Then the method is applied to structure designs, mechanism andmaterial designs by a number of benchmark examples. Finally, in order to further improvecomputational efficiency and overcome the difficulty that the level set method cannot generate newmaterial interfaces during the optimization process, the topological derivative analysis isincorporated into the level set method for topological optimization, and a topological derivativeand level set algorithm for topological optimization is proposed.

关键词： Level set method Topology optimization Mean curvature flow Materialdesign Mechanism design Topological derivative

Corrosion Fatigue Behavior of Duplex Stainless Steel in 3.5% Sodium Chloride Solution

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Journal of university of science and technology Beijing 2001年第2期8卷 133-136页

作者： S. H Abubakir, Yinshun Wu, Baofeng Ding, Jiuqing Li Bei Cao (Material science and engineering school, university of science and technology Beijing, Beijing 100083, china) Material Sci. and engineering school University of Science and Technology Beijing 100083 China

The corrosion fatigue behavior of duplex stainless steel (DSS) was studied at different cyclic stress levels in 3.5%NaCl (mass fraction, so as the follows) solution (pH=7) at 50 degreesC. The results showed that DSS was susceptible to pitting corrosion and corrosion fatigue. Both intergranluar corrosion cracking and transgranlular corrosion cracking initiated at the bottom of pitting holes. Furthermore, the corrosion fatigue properties of DSS in 3.5%NaCl solution may be relatived to complex electrochemical and mechanical coupling effects between the three phases (austenite, ferrite and martensite), where martensite and ferrite were anodic in the corrosion cell and could be prone to cracking under certain condition.

关键词： corrosion fatigue duplex stainless steel sodium chloride solution

Nonholonomic mapping theory of autoparallel motions in Riemann-Cartan space

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science china(Physics,Mechanics & Astronomy) 2010年第9期53卷 1707-1715页

作者： GUO YongXin1,LIU Chang2,WANG Yong3,LIU ShiXing1 & CHANG Peng2 1 College of Physics,liaoning university,Shenyang 110036,china 2 school of Aerospace engineering,Beijing Institute of technology,Beijing 110081,china 3.school of Basic Medical science,Guangdong Medical College,Dongguan 523808,china College of Physics Liaoning University Shenyang China school of Aerospace engineering Beijing Institute of Technology Beijing China school of Basic Medical science Guangdong Medical College Dongguan China

The method of nonholonomic mapping is utilized to construct a Riemann-Cartan space embedded into a known Riemann-Cartan space,which includes two special cases that a Weitzenbck space and a Riemann-Cartan space are respectively embedded into a Euclidean space and a Riemann *** means of this mapping theory,the nonholonomic corresponding relation between the autoparallels of two Riemman-Cartan spaces is *** particular,an autoparallel in a Riemann-Cartan space can be mapped into a geodesic line in a Riemann space and an autoparallel in Weitzenbck space be mapped into a geodesic line in Euclidean *** on the Lagrange-d'Alembert principle,the equations of motion for dynamical systems in Riemman-Cartan space should be autoparallel equations of the *** applications,the problem of autoparallel motion of spinless particles,Chaplygin's nonholonomic systems and a rigid body rotating with a fixed point are investigated in space with torsion.

关键词： nonholonomic mapping Riemann-Cartan space connection torsion autoparallel

Mechanism of Breakdown in Laminar-Turbulent Transition of Incompressible Boundary Layer on a Flat Plate

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Transactions of Tianjin university 2007年第2期13卷 79-87页

作者：唐洪涛罗纪生周恒 school of mechanical engineering Tianjin University

Temporal mode direct numerical simulation was done for the process of laminar-turbulent transition in an incompressible boundary layer on a flat plate. The analysis of the results showed that during the breakdown process of laminar-turbulent transition, the modification of the mean flow profile by the disturbances led to a remarkable change in its stability characteristics, manifested in the significant enlargement of the linear unstable zone and the maximum amplification rate, and led to that many more disturbances were excited and enhanced rapidly, correspondingly the turbulent energy also increased rapidly, and the mean flow profiles evolved swiftly from laminar to turbulent. It was also found that if the oblique waves in the initial disturbances did not form symmetrical pairs, the subsequent span-wise mean velocities would, in general, be nonzero due to nonlinear interaction, which would have a great effect on the stability characteristics and also implied that the turbulence obtained by direct numerical simulation might not be fully a random process.

关键词： boundary layer transition direct numerical simulation breakdown

Study of Bake Hardenability and Strengthening Mechanism of Hot Rolled Low Carbon Steel

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Journal of Iron and Steel Research International 2011年第S1期18卷 337-341页

作者： LI Wei-juan 1,WANG Guo-dong 2 (1.school of Materials and Metallurgy,university of science and technology liaoning,anshan 114051,china 2.The State key Laboratory of Rolling and Automation,Northeastern university,Shenyang 110004,china) Univ Sci & Technol liaoning Sch Met & Mat Anshan 114051 Peoples R China Northeastern Univ State Key Lab Rolling & Automat Shenyang 110004 Peoples R China

The controlled rolling and controlled cooling,bake hardening experiments have been carried out for the test steel,mechanical property test of the sample and microstructure analysis have been made by tensile testing machine,optical microscope,TEM and X-ray *** results show that fine and uniform microstructures can achieve much higher BH and BHT values;With the increase of pre-strain there is a trend of increase first and then decrease in the BH and BHT values;bake hardening mechanism mainly consists of Cottrell atmosphere strengthening,second phase strengthening,dislocation strengthening.

关键词： bake hardening BH value BHT value

mechanical Properties and Erosive Wear Resistance of Zirconia Toughened Al_2O_3-TiC Ceramics

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International Journal of Minerals,Metallurgy and Materials 2000年第2期14卷 110-114页

作者： Lihua Xu Fang Lian Yuyan Guo Qiang Zhen Jose Maria Fonte Ferreira Fuming Wang Wenchao Li(Material science and engineering school, university of science and technology Beijing, Beijing 100083, china)(Metallurgy school, university of science and Tech Material science and engineering school University of Science and Technology Beijing Beijing 100083 China Metallurgy school University of Science and Technology Beijing Beijing 100083 China Department of Ceramic and Glass engineering University of Aveiro 3810-193 Aveiro Portugal

The effect of ZrO2, content on the fracture toughness, flexural strength and Vickers hardness as well as the erosive wear resistan properties of zirconia toughened Al2O3-TiC ceramic composites has been investigated. The results showed that the improvement in fracture toughness and flexure strength of composites with the content of zirconia less than 50% and 10% in mass fraction respectively,is primarily attributed to stress-induced transformation toughening by the analyse of X-ray diffraction. The dependance of erosion wear resistance on the attak angle and the content of ZrO2, panicles of the composites was also revealed. It is found that the erosion rate of the composites has a sharp rise at a attack angle over 65°. This phenomenon is due to a brittle response to the erosion test by microsmictural observation on eroded surface.

关键词： mechanical properties, erosion ceramic composites

MATRIX ALGEBRA ALGORITHM OF STRUCTURE RANDOM RESPONSE NUMERICAL CHARACTERISTICS

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Chinese Journal of mechanical engineering 2003年第2期16卷 149-152页

作者： Mei YulinWang XiaomingWang DelunDepartment of mechanical engineering,Dalian university of technology,Dalian 116024,china Department of mechanical engineering Dalian University of Technology Dalian 116024

A new algorithm of structure random response numerical characteristics, namedas matrix algebra algorithm of structure analysis is presented. Using the algorithm, structurerandom response numerical characteristics can easily be got by directly solving linear matrixequations rather than structure motion differential equations. Moreover, in order to solve thecorresponding linear matrix equations, the numerical integration fast algorithm is presented. Thenaccording to the results, dynamic design and life-span estimation can be done. Besides, the newalgorithm can solve non-proportion damp structure response.

关键词： matrix algebra algorithm structure random response numericalcharacteristics numerical integration fast algorithm non-proportion damp