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The Dissymmetry of Friction Stir Welding Joints and Va-riable Polarity Plasma Arc Welding Joints Study

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稀有金属材料与工程 2011年第S4期40卷 84-89页

作者： Chen Shujun,Wang Long,Yu Yang Beijing University of Technology Mechanical Engineering,Beijing100022,China Beijing Univ Technol Mech Engn Beijing 100022 Peoples R China

2219 aluminum alloys welding joints were prepared by Friction stir welding (FSW) and Variable polarity plasma arc welding (VPPAW).The microstructure of joints was characterized by means of OM,SEM,and *** measurements was performed to differentiate the joint zones and to evaluate the symmetry level of the joints with the help of nano-indentation *** dissymmetry of microstructure and mechanical properties was found both in FSW joint and VPPAW *** dissymmetry in FSW joint can not be suppressed due to the nature of the mixing head,but the symmetry and satisfactory welding joint can be obtained by changing the working pattern of VPPAW.

关键词： FSW VPPAW nano-indentation experiment "Half-leaf" zone dissymmetry

A note on spline wavelets

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Chinese Science Bulletin 1997年第15期42卷 1250-1253页

作者： LIU YoumingDepartment of Applied Mathematics, Beijing Polytechnic University, Beijing 100022, China Department of Applied Mathematics Beijing Polytechnic University Beijing China

THE B-spline wavelets Nm （x） play an important role in the approximation theory sincethey are piecewise polynomials so that they may be used to fit a function and its derivatives atthe integers. However, except for m=1, 2, they do not have the interpolating property (i.e. Nm（n） ≠δn0. In this work, we shall construct a family of scaling functions of fatherwavelets which have the interpolating property and whose Fourier transforms are spline func-tions. As usual, these functions can be orthogonalized by Meyer’s technique and the corre-sponding mother wavelets ψ may be found by the

关键词： wavelets scaling function cardinality.

A　Surface　Heat　Disturbance　Method　for　Measuring　Local　Tissue　Blood　Perfusion　Rate

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Journal of Thermal Science 1996年第1期5卷 28-33页

作者： Peng Jianshu Tian Yongquan(Beijing Polytechnic University,BeiJing 100022,China) Beijing Polytechnic University Beijing China

A non-damage method for measuring local tissue blood perfusion rate by surface heat disturbance and its two special embodiments for realizing this measurement are presented in this *** the derivation of mathematical model,the Pennes equation is used, and two parameters which are very difficult to be known-the arterial blood temperature Tαand the metabolic heat generation rate qm,have been *** it has provided a feasible basis for *** this paper,the performance and the adaptable condition of the measurement method and its structure peculiarities are discussed over a wide variety of ***,the effectiveness of the measurement method has been demonstrated by means of the quantitative measurement of tissue in vitro,the comparative measurement of animal under artificial perfusion and the dependence measurement in human body.

关键词： blood perfusion rate tissue heat disturbance method.

Effects of Surface-Active Elements Sulfur on Flow Patterns of Welding Pool

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Journal of Materials Science & Technology 2005年第3期21卷 408-414页

作者： Yuzhen ZHAO, Yongping LEI and Yaowu SHI School of Materials Science and Engineering, Beijing University of Technology, Beijing 100022, China School of Materials Science and Engineering Beijing University of Technology Beijing 100022 China

A 3D mathematical model is developed to calculate the temperature and velocity distributions in a moving gas tungsten arc (GTA) welding pool with different sulfur concentrations. It has been shown that, the weld penetration increases sharply with increasing sulfur content. When sulfur content increases beyond 80 × 10-6, the increase in sulfur content does not have an appreciable difference on the welding pool size and shape, and the depth/width remains constant. Sulfur changes the temperature dependence of surface tension coefficient from a negative value to a positive value and causes significant changes on flow patterns. The increase in soluble sulfur content and the decrease at free surface temperature can extend the region of positive surface tension coefficient. As sulfur content exceeds 125×10-6, the sign of surface tension coefficient is positive. Depending upon the sulfur concentrations, three, one or two vortexes that have different positions, strength and directions may be found in the welding pool. The contrary vortexes can efficiently transfer the thermal energy from the arc, creating a deep welding pool. An optimum range of sulfur content is 20-150×10-6.

关键词： Surface-active elements Sulfur Plow patterns Depth/width

Estimation of Temperature Fields in Local Tissues During Intracavitary Hyperthermia

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Journal of Thermal Science 1999年第1期8卷 38-43页

作者： Nan Qun Hu Zhengjun Peng Jianshu(Beijing Polytechnic University, Beijing 100022, China) Beijing Polytechnic University Beijing China

This paper presents a heat transfer model for the hyperthermia treatment of cervix cancer using a intracavitary microwave applicator and based on which the 3-D finite element simulation of the temperature fields have done. Before then the specific absorption rate (SAR) distribution for the transvaginal probe have been measured in a phantom. The variations of the parameters have been investigated, too, for optimization. At last, the results of simulation are compared to that measured in the phantom and some instructive conclusions are presented for critical application.

关键词： hyperthermia treatment prediction of temperature fields 3-D finite element simulation.

Anisotropic Scattering in BaTiO3: Ce Single Crystal

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Chinese Journal of Lasers 1997年第1期B6卷 15-20页

作者： WANG Rongping ZHOU Jinfeng ZENG Lingzhi(Department of Applied Physics,Beijing Polytechnic University,beijing 100022) Beijing Polytechnic Univ Beijing China

A kind of anisotropic scattering in BaTO3:Ce is reported for the perpendicularly and obliquely extraordinary polarized incident beam. The scattering angle is determined by the phase-matching conditions. The experimental results agree well with the theoretical analysis. On the other hand, a new kind of near 90° scattering is presented, a possible mixing mechanism of the light climbing and the photovoltaic effect in BaTiO3:Ce is also pointed out.

关键词： anisotropy scattering light climbing effect photovoltaic effect BaTiO3: Ce crystal

MNDO research on alkylation of DNA bases by the non-α-position metabolite of 3, 5-dimethyl-N-nitrosopeperazine

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Chinese Science Bulletin 1997年第8期42卷 698-700页

作者： ZHONG Rugang and DAI QianhuanCenter for Cancer Chemistry and Bioengineering, Beijing Polytechnic University, Beijing 100022. China Center for Cancer Chemistry and Bioengineering Beijing Polytechnic IJniversity Beijing China

IT is a commonly accepted concept that having formed alkyldiazonium ions after α-hydroxyla-tion,the metabolites of N-nitroso compounds(NNCs)combine with DNA and initiate *** the complex relationship between carcinoge... 详细信息

关键词： nitrosopeperazine di-region theory alkylation of DNA MNDO.

Quantal conserved charge in non-Abelian Chern-Simons theories

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Chinese Science Bulletin 1999年第3期44卷 207-210页

作者： LI ZipingCCAST( World Laboratory), Beijing 100080, China Department of Applied Physics, Beijing Polytechnic University, Beijing 100022, China CCAST(World Laboratory) Beijing China Department of Applied Physics Beijing Polytechnic University Beijing China

Based on the global canonical symmetry of the path integral in phase space, the quantal conserved angular momentum and BRS charge for non-Abelian Chern-Simons (CS) theories have been derived. The possibility of the oc... 详细信息

关键词： path integral conservation laws Chern-Simons theory fractional spin BRS-invariance.

On the Auslander-Reiten Quiver with OrientedCyclesof Representation-finite Algebras

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Chinese Quarterly Journal of Mathematics 1998年第3期13卷 43-47,页

作者： Yao Hailou (Department of Mathematics,Beijing Polytechnic University,Beijing,100022)

Let A be a basic,connected finite dimensional algebra over an algebraically closed field with finite representation type, α(A) be the maximum of set consisting of numbers of indecomposable summands in the middle term of Auslander Reiten sequences in mod A. In this paper we show that if α(A)=1, then Γ A contains oriented cycles if and only if Γ A contains DT r periodic modules. When α(A)2 we give counterexamples to the assertion.

关键词： Auslander Reiten quiver Auslander Reiten sequences oriented cycles DT r periodic molules