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Lie Point Symmetries of Differential-Difference Equations

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Communications in Theoretical Physics 2004年第5期41卷 645-648页

作者： DING Wei~1 TANG Xiao-Yan~(2,3) 1 Department of Applied Mathematics,shanghai Jiao Tong University,shanghai 200030,china2 Department of Physics,shanghai Jiao Tong University,shanghai 200030,china3 State Key Laboratory of Scientific and engineering Computing,Institute of Computational Mathematics and Scientific engineering Computing,Academy of Mathematics and system Sciences,the Chinese Academy of Sciences,P.O.Box 2719,Beijing 100080,china Department of Applied Mathematics Shanghai Jiao Tong University Shanghai 200030 China Department of Physics Shanghai Jiao Tong University Shanghai 200030 China State Key Laboratory of Scientific and engineering Computing Institute of Computational Mathematics and Scientific Engineering Computing Academy of Mathematics and System Sciences the Chinese Academy of Sciences P.O. Box 2719 Beijing 100080 China

In this paper,the classical Lie group approach is extended to find some Lie point symmetries of differential-difference *** reveals that the obtained Lie point symmetries can constitute a Kac-Moody-Virasoro algebra.

关键词： Lie point symmetry differential-difference equation Kac Moody-Virasoro algebra

Effects of Melt Thermal Treatment on A356 Alloy

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Journal of Materials Science & Technology 2003年第2期19卷 152-154页

作者： Jun WANG, Shuxian HE, Baode SUN and Yaohe ZHOUSchool of Materials Science and engineering, shanghai Jiao Tong University, shanghai 200030, china Sch. of Mat. Sci. and Eng. Shanghai Jiaotong Univ. Shanghai 200030 China

To increase the casting quality of hypoeutectic Al-Si alloys, the effects of melt thermal treatment on the solidification structure of the A356 alloy were analyzed by a factorial experiment, in which the overheated melt was mixed with the low temperature melt. Experimental results show that the elongation ratio and strength of the treated samples increase remarkably compared with the control sample. The primary dendrite size reduces dramatically and the dendrite changes from columnar to equiaxed, with a little change of the secondary dendrite arm spacing (SDAS). Combined with the measurement of the nucleation undercooling, it is concluded that the solidification structure and refining effect are dependent primarily on the low temperature melt. The refining mechanism is believed as a result of the multiplication of the nuclei in the melt thermal treatment procedure.

关键词： A356 Melt thermal treatment Solidification structure

STUDY ON SINGULAR CONFIGURATIONS AND COMPUTER SIMULATION OF 6R ROBOT

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Chinese Journal of Mechanical engineering 2004年第2期17卷 177-180页

作者： Zhang Kai Hu Dejin Liu Chengliang School of Mechanical engineering,shanghai Jiaotong University,shanghai 200030, china School of Mechanical engineering Shanghai Jiaotong University 上海 200030

When robot is at singular configuration, the limited hand velocity wouldrequire some joints with infeasible speeds so as to lead unsafely of the system. A method of solvingthe approximate velocity of joint near singular configuration point by adding damped vector isproposed and a modified algorithm is provided. With the analysis of J^(-1) the singularconfigurations of 6R robot are divided into structure boundary singularity , boundary singularity ,inner singularity and wrist singularity. The conditions of singularities of the robot have beenascertained. The computer simulations of the singularities of the robot are developed, which havemany advantages over previous description methods of the singular configurations of robot. With thehelp of boundary singularity analysis, a application in welding trajectory planning checking of therobot has been carried out and the simulation result proved visualized and useful.

关键词： Robot Singular configuration Computer simulation

Six-frame Algorithm Insensitive to the Linear Reference Phase and Detector Nonlinearity Errors for Phase-stepping Interferometry

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Chinese Journal of Lasers 1997年第2期B6卷 117-121页

作者： WEI Chunlong(Department of Electronic engineering, shanghai University Jiading Campus,shanghai 201800, china)CHEN Mingyi DING Zheng(Department of Mechanic engineering, shanghai University Jiading Campus),shanghai 201800, china)WANG Zhijiang(shanghai Inst shanghai Univ Shanghai China

A new six-frame algorithm based on Hariharan' s five-frame algorithmis derived. Although six-frame interferograms are needed, the new algorithm is immune to the effect of reference phase error or the second order detector nonlinearity ***, if they exist simultaneously, the new algorithm is insensitive to both of the errors. It is better than B. Zhao and Y. Surrel's six-frame algorithm to some extent.

关键词： interferometry phase-stepping algorithm

NEAR WAKE OF A MODEL HORIZONTAL-AXIS WIND TURBINE

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Journal of Hydrodynamics 2009年第2期21卷 285-291页

作者： HU Dan-mei DU Zhao-hui School of Power and Enviromental engineering Shanghai University of Electric Power Shanghai 200090 China School of Mechanical engineering Shanghai Jiao Tong University Shanghai 200240 China

An experimental investigation on the properties of the near wake behind the rotor of a Horizontal-Axis Wind Turbine （HAWT） was carried out at model scale. Measurements were made with a stationary slanted hot-wire anemometer using the technique of phase-locked averaging. The primary aim is to study the formation and development of the three-dimensional wake. Five axial locations were chosen within four chord lengths of the blades over a range of tip speed ratios. The results show that during the downstream developmerit of the wake, the wake centre traces a helical curve with its rotation direction opposite to that of the rotor. The distribution of mean velocity behind the HAWT rotor reveals an expansion and a decay of the three-dimensional wake. The shapes of the mean velocity distribution are similar along the blades span at the same downstream axial location. It is shown that the turbulence levels in the wake are higher than those in the non-wake region. The circumferential component and the radial component of the turbulence intensity are higher than the axial component. Our study offers some food of thought for better understanding of the physical features of the flow field as well as the performance of HAWT.

关键词： horizontal-axis wind turbine wake flow hot-wire anemometry experimental

Research on Vibration Properties of the Drill-punch Mechanism for Taphole Drill

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Journal of University of Science and Technology Beijing 2001年第4期8卷 311-313页

作者： Jianping Liu, Yongfang Liao 1) Mechanical engineering School, University of Science and Technology Beijing. Beijing 100083, china 2) shanghai Baoshan Iron & Steel Corporation. shanghai 201914, china Mechanical engineering School University of Science and Technology Beijing Beijing 100083 China shanghai Baoshan Iron and Steel Corporation Shanghai 201914 China

A new type taphole drill was designed. The vibration properties of them drill-punch mechanism for the new type taphole drill were researched, the laws of its inherent characteristics were found. The measures to add punch amplitude and to reduce traverse vibration were put forward. The result showed that decreasing the frequency of vibration motors or increasing the stiffness of springs, and increasing excitation force can improve the vibration properties of the properties of the drill-punch mechanism.

关键词： taphole drill equipment in the cast house vibrating machinery

Identification and classification of all potential hemolysin encoding genes and their products from Leptospira interrogans serogroup Icterohaemorrhagiae serovar Lai

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Acta Pharmacologica Sinica 2005年第4期26卷 453-461页

作者： Yi-xuan ZHANG~(2,3,4,5) Yan GENG(2,3,4,5) Bo BI~(2,4) Jian-yong HE~4 Chun-fu WU~4 Xiao-kui GUO~3 Guo-ping ZHAO~(2,4,6,7) 2 Research Center of Biotechnology,shanghai Institutes for Biological Sciences,Chinese Academy of Sciences,shanghai 200233,china 3 Department of Microbiology and Parasitology,shanghai Second Medical University,shanghai 200025,china 4 The School of Pharmaceutical engineering,Shenyang Pharmaceutical University,Shenyang 110016,china 6 Chinese National Human Genome Center at shanghai,ZhangJiang High Tech Park,shanghai 201203,china Research Center of Biotechnology Shanghai Institutes for Biological Sciences Chinese Academy of Sciences Shanghai China Department of Microbiology and Parasitology Shanghai Second Medical University Shanghai China The School of Pharmaceutical engineering Shenyang Pharmaceutical University Shenyang China Chinese National Human Genome Center at shanghai ZhangJiang High Tech Park Shanghai China

Aim:To identify and classify all potential hemolysin candidates of Leptospirainterrogans serogroup Icterohaemorrhagiae serovar ***:All of thepotential hemolysin encoding genes were characterized in *** geneswere cloned and expressed in Escherichia *** hemolytic activities of theexpressed proteins were assayed observing the hemolysis on sheep blood *** activities of the hemolysin candidates were measuredby thin-layer chromatography(TLC)and HPLC for *** and secretion of the hemolysins in L interrogans were studied byreverse transcription polymerase chain reaction,Western blot,and enzyme-linkedimmunosorbent *** and Conclusion:The hemolytic activities ofhemolysin candidates(LA0327,LA0378,LA1027,LA1029,LAI650,LA3050,LA3937,LA4004)from L interrogans strain Lai were *** were furtherdivided into two groups,sphingomyelinase hemolysins and non-sphingomyelinasehemolysins,based on their ability to hydrolyze *** of thesehemolysins were actually expressed in living L interrogans and some of themwere secreted into the *** study establishes an essential findcomplete basis for further studying the contribution of hemolysins to the patho-genesis of L interrogans.

关键词： hemolysin Leptospira interrogans sphingo myelinase

Central simple Poisson algebras

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Science china Mathematics 2004年第2期47卷 245-263页

作者： SU Yucai & XU XiaopingDepartment of Mathematics, shanghai Jiaotong University, shanghai 200030, china Institute of Mathematics, Academy of Mathematics and system Sciences, Chinese Academy of Sciences, Beijing 100080, china Department of Mathematics Shanghai Jiaotong University Shanghai China Institute of Mathematics Academy of Mathematics and System Sciences Chinese Academy of Sciences Beijing China

Poisson algebras are fundamental algebraic structures in physics and symplectic geometry. However, the structure theory of Poisson algebras has not been well developed. In this paper, we determine the structure of the central simple Poisson algebras related to locally finite derivations, over an algebraically closed field of characteristic *** Lie algebra structures of these Poisson algebras are in general not finitely-graded.

关键词： Poisson algebra, locally-finite operator, derivation, finitely-graded, isomorphism class.

A THREE-DIMENSIONAL DESINGULARIZED HIGH ORDER PANEL METHOD BASED ON NURBS

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Journal of Hydrodynamics 2008年第2期20卷 137-146页

作者： GAO Zhi-liang ZOU Zao-jian State Key Laboratory of Ocean engineering Shanghai Jiaotong University Shanghai 200030 China School of Naval Architecture Ocean and Civil Engineering Shanghai Jiaotong University Shanghai 200030 China

A desingularized high order panel method based on Non-Uniform Rational B-Spline （NURBS） was developed to deal with three-dimensional potential flow problems. A NURBS surface was used to precisely represent the body geometry. Velocity potential on the body surface was described by the B-spline after the source density distribution on the body surface had been solved. The collocation approach was employed to satisfy the Neurnann boundary condition and Gaussian quadrature points were chosen as both the collocation points and the source points. The singularity was removed by a combined method, so the process of the numerical computation was non-singular. In order to verify the method proposed, the unbounded flow problems of sphere and ellipsoid, the wave-making problem of a submerged ellipsoid were chosen as computational examples. It is shown that the numerical results are in good agreement with analytical solutions and other numerical results in all cases, and sufficient accuracy of numerical solution can be reached with a small number of panels.

关键词： potential flow high order panel method Non-Uniform Rational B-Spline (NURBS) desingularization