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AN　INTEGRATEDC　METHoD　FoR　CoMpUTING　CoMpUTING　THE　INTERNAL　AND　EXTERNAL　VISCoUS　FLoW　FIELD　ARoUND　THE　DUCTED　p.o.ULSoR　BEHIND　AN　AXISYMMETRIC　BoDY

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Journal of Hydrodynamics 1995年第3期7卷 72-83页

作者： Zhou Lian-di Zhao Feng(China Ship Scientific Research Center, p.o. box 116, Wuxi 214082, p. R. China) China Ship Scientific Research Cent Wuxi China

This paper presents an effective method for computing the internal and external viscous flow field around the ducted p.o.ulsor behind an axisymmetric they by using a new Navier-Stokes equations solver with primitive variable continuity equation formulation. In the present numerical method, the calculation equation for pressure with well-defined coefficient,which form is similar to the artificial compressibility method, is developed. A semi-staggered grid system is adopted. Not only the advantage of staggered grid system can be retained but the boundary conditions on the inner and outer surface of the duct can be also carried out easily. By using a special grid system and the p.o.ramming technique for implementing the jump boundary condition on the duct surfaces, the internal and external viscous flow field around the ducted p.o.ulsor behind the axisymmetric they may be calculated integrally in an unified numbered grid system. Some configurations are calculated and compared with experimental date and numerical results of other methods. Illustrative calculations are also presented for a stern of axisymmetric body with the backstep fitted a duct to illustrate the capability of the present method. Beside that, the effect of axial distribution of they force is considered and discussed in order to extend the application range of the present method.

关键词： ducted p.o.ulsor viscous flow semi-staggered grid

Build Axial Gradient Field by Using Axial Magnetized permanent Rings

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Journal of Materials Science & Technology 2002年第6期18卷 483-484页

作者： Quanling pENGInstitute of High Energy physics, Chinese Academy of Sciences p.o. box 918-9, Beijing 100039, China Chinese Acad Sci Inst High Energy Phys Beijing 100039 Peoples R China

Axial magnetic field p.o.uced by an axial magnetized permanent ring was studied. For two permanent rings, if they are magnetized in the same directions, a nearly uniform axial field can be p.o.uced. If they are magnetized in op.o.ite direction, an axial gradient magnetic field can be generated, with the field range changing from-Bo to Bo- A permanent magnet with a high axial gradient field was fabricated, the measured results agree with the pANDIRA calculation very well. For wider usage, it is desirable for the field gradient to be changed. Some methods to p.o.uce the variable gradient field are presented. These kinds of axial gradient magnetic field can also be used as a beam focusing for linear accelerator if the periodic field can be p.o.uced along the beam trajectory. The axial magnetic field is something like a solenoid, large stray field will leak to the outside environment if no method is taken to control them. In this paper, one method is illustrated to shield off the outside leakage field.

关键词： Axial magnetized permanent ring Electron beam Leakage

CRITICAL ISSUES oF poWDER METALLURGY TURBINE DISKS

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Acta Metallurgica Sinica(English Letters) 1996年第6期9卷 467-471页

作者： K.M. Chang(Department of Mechanical and Aerospace Engineering,West Virginia University, p.o. box 6160, Morgantown,WV 26506, USA West Virginia Univ Morgantown United States

p/M superalloy disks obtain their final strength by app.o.riate heat treatments; the maximum attainable strength depends on the rapid cooling rate from the solution annealing. A rapid quench of a large disk forging can cause two p.o.lems, surface cracking and shape *** the past,many attempts emp.o. the finite element code to model and to predict temperature evolution and induced stress distribution in a large turbine disk. The major difficulty was the correct description of alloy behavior; particularly the thermomechanical p.o.erties and the failure criteria of material during the cooling. High temperature fatigue resistance is always the key requirement for disk materials. New methodology of residual life management emphasizes the initiation as well as the p.o.agation of the cracks developed under the service conditions. one of major challenges to p/M superalloys is the time-dependent behavior of fatigue cracking, which relates to the well-known SAGBo (stress-assisted grain boundary oxidation) phenomenon.A great effort has been done to understand the micro-mechanism of time-dependent fatigue crack p.o.agation resulted in the second generation of p/M superalloys. Further imp.o.ement on temperature capability of disk alloys at rim area may lead to the idea of dual-p.o.erty *** grain structures at different portions of a large disk are possible,as the p.o.erty requirements for different locations are different. This goal is achievable if the thermal history at specific disk locations can be controlled to develop desirable microstructures and *** suggestions on the future direction of research efforts will be discused.

关键词： superalloy disk,powder metallurgy (p/M) quench cracking,fatigue crack p.o.agation SAGBo (stress-assisted grain boundary oxidation),dual-p.o.erty disk grain size

A parameterization of Cooling Rate Calculation under the Non-LTE Condition: Multi-Level Model

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Advances in Atmospheric Sciences 1989年第4期6卷 403-413页

作者： Xun Zhup.o.ram in Atmospheric and oceanic Sciences. p.o. box 308, princeton University,princeton, NJ 08542, USA p.o.ram in Atmospheric and oceanic Sciences Princeton University Princeton USA

Calculations of cooling rate by Co2 15 μm band in the earth's upper mesosphere and lower thermosphere be-come very difficult because of the non-LTE. This is primarily due to the nonlinear vibration-vibrational (VV) transition p.o.esses between Co, molecules in different states. This paper suggests that the non-LTE source function be parameterized as a linear combination of two limiting source functions. one limiting source function neglects the VV transitions while the other limiting source function assumes VV transitions being dominant. These two limiting source functions can be derived by linear models. The parameterization schemes p.o.osed here can be applied to the general circulation models including those non-LTE regions.

关键词： rate LTE Multi-Level Model

GENERAL DIFFERENCE SCHEMES WITH INTRINSICpARALLELISM FoR SEMILINEAR pARABoLIC SYSTEMS oFDIVERGENCE TYpE

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Journal of Computational Mathematics 1999年第4期17卷 337-352页

作者： Yu-lin Zhou Guang-wei Yuan(Laboratory of Computational physics, Center of Nonlinear Studies, Institute of Applied physics and Computational Mathematics, p.o. box 8009, Beijing 100088, China) Laboratory of Computational physics Center of Nonlinear Studies Institute of Applied Physics and Computational Mathematics P.O. Box 8009 Beijing 100088 China

In this paper the general finite difference schemes with intrinsic parallelism for the boundary value p.o.lem of the semilinear parabolic system of divergence type with bounded coefficients are constructed, and the existence and uniqueness of the difference solution for the general schemes are p.o.ed. And the convergence of the solutions of the difference schemes to the generalized solution of the original boundary value p.o.lem of the semilinear parabolic system is obtained. The multidimensional p.o.lems are also studied.

关键词： difference scheme intrinsic parallelism semilinear parabolic system convergence

EXpANSIoN oF STEp-TRANSITIoN opERAToR oF MULTI-STEp METHoD AND ITS AppLICATIoNS (Ⅱ)

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Journal of Computational Mathematics 2002年第2期20卷 461-478页

作者： Yi-fa Tang(State Key Laboratory of Scientific and Engineering Computing, ICMSEC, Academy of Mathematics and System Sciences, Chinese Academy of Sciences, p.o. box 2719, Beijing 100080, China) 中科院数学与系统科学院 LSEC ICMSEC CAS 北京 100080

We give some formulae for calculation of the expansions for (1) composition of step-transition operators (STo) of any two difference schemes (DS) for oDE's, (2) inverse operator of STo of any DS, and (3) conjugate ope... 详细信息

关键词： Step-transition operator Expansion Composition Inverse operator Conjugate operator.

oN THE CoUpLING oF BoUNDARY INTEGRAL AND FINITE ELEMENT METHoDS FoR SIGNoRINI p.o.LEMS

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Journal of Computational Mathematics 1998年第6期16卷 561-570页

作者： Wei-jun Tang Hong-yuan Fu Long-jun Shen(Laboratory of Computational physics, Institute of Applied physics and Computational Mathematics, p.o. box 8009, Beijing 100088, China) 北京应用物理和计算数学所北京

In this paper, a exterior Signorini p.o.lem is reduced to a variational inequality on a bounded inner region with the help.o. a coupling of boundary integral and finite element methods. We established a equivalence between the original exterior Signorini p.o.lem and the variational inequality on the bounded inner region coupled with two integral equations on an auxiliary boundary. We also introduce a finite element app.o.imation of the variational inequality and a boundary element app.o.imation of the integral equations. Furthermore, the optimal error estimates are given.

关键词： boundary element finite element Signorini p.o.lems

A RIGoRoUS DERIVATIoN oF THE GRoSS-pITAEVSKII HIERARCHY FoR WEAKLY CoUpLED TWo-DIMENSIoNAL BoSoNS

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Acta Mathematica Scientia 2010年第3期30卷 841-856页

作者：刘创业 Wuhan Institute of physics and Mathematics Chinese Academy of Sciences

In this article, we consider the dynamics of N two-dimensional boson systems interacting through a pair potential N-1Va（xi -xj） where Va（x） = a^-2V（x/a）. It is well known that the Cross-pitaevskii （Gp） equation is a nonlinear SchrSdinger equation and the Gp hierarchy is an infinite BBGKY hierarchy of equations so that if ut solves the Gp equation, then the family of k-particle density matrices { k ut, k≥1} solves the Gp hierarchy. Denote by ψN,t the solution to the N-particle Schrodinger equation. Under the assumption that a = N^-ε for 0 〈 ε 〈 3/4, we p.o.e that as N→∞ the limit points of the k-particle density matrices of CN,t are solutions of the Gp hierarchy with the coupling constant in the nonlinear term of the Gp equation given by f V（x） dx.

关键词： Cross-pitaevskii equation Boson system density matrix BBGKY hierarchy

App.o.imate Inertial Manifolds to the Generalized Symmetric Regularized Long Wave Equations with Damping Term

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Acta Mathematicae Applicatae Sinica 2003年第2期19卷 191-204页

作者： Bo-ling Guo, Ya-dong ShangInstitute of Applied physics and Computational Mathematics, p.o. box 8009, Beijing 100088, China Institute of Applied physics and Computational Mathematics Beijing China

Abstract In the present paper, we construct two app.o.imate inertial manifolds for the generalized symmetric regularized long wave equations with damping term. The orders of app.o.imations of these manifolds to the gl... 详细信息

关键词： Keywords Symmetric regularized long wave equation periodic initial value p.o.lem long time behavior app.o.imate inertial manifolds damping term