开放的ladder型无反转激光系统的稳定性分析

利用开放的ladder型无反转激光系统的密度矩阵运动方程组的定态解和激光场运动方程分析了系统的稳定性。结果表明：如果增益大于激光腔损耗，则零解是不稳定的；如果增益小于激光腔损耗，则零解是稳定的；如果增益大于激光腔损耗，则非零解是稳定的。     

Boundary knot method for 2D and 3D Helmholtz and convection–diffusion problems under complicated geometry

The boundary knot method (BKM) of very recent origin is an inherently meshless, integration‐free, boundary‐type, radial basis function collocation technique for the numerical discretization of general partial differential equation systems. Unlike the method of fundamental solutions, the use of non‐singular general solution in the BKM avoids the unnecessary requirement of constructing a controversial artificial boundary outside the physical domain. The purpose of this paper is to extend the BKM to solve 2D Helmholtz and convection–diffusion problems under rather complicated irregular geometry. The method is also first applied to 3D problems. Numerical experiments validate that the BKM can produce highly accurate solutions using a relatively small number of knots. For inhomogeneous cases, some inner knots are found necessary to guarantee accuracy and stability. The stability and convergence of the BKM are numerically illustrated and the completeness issue is also discussed. Copyright © 2003 John Wiley & Sons, Ltd.     

激光二极管线阵光束变换研究

推导出激光二极管线阵光束通过透镜系统的光强分布表达式，分析了出射光束的传输特性，设计一种凹柱透镜的光束变换系统得到一维均匀光强分布。此外，给出扩展角宽度的计算公式。     

Solution of large deformation contact problems with friction between Blatz-Ko hyperelastic bodies

The present paper is devoted to the analysis of the contact problems with Coulomb friction and large deformation between two hyperelastic bodies. One approach to separate the material nonlinearity and contact nonlinearity is presented. The total Lagrangian formulation is adopted to describe the geometrically nonlinear behavior. Nondifferentiable contact potentials are regularized by means of the augmented Lagrangian method. Numerical examples are carried out in two cases: rigid-deformable contact and deformable-deformable contact with large slips. The numerical results prove that the proposed approach is robust and efficient concerning numerical stability.     

A new bubble-point-pressure correlation for the binary LiBr/H2O solution

In accord with the increasing concern about the global environmental issues, the absorption refrigeration heat-pump systems are currently being considered very promising and attractive. For the purpose of supporting the advanced R&D technology in this area, we have developed a novel correlation to represent the bubble-point pressures of LiBr H₂O solutions. The developed correlation covers the most extensive range of validity ever proposed: 273–483 K for temperatures, 0.05 kPa to 1.0 MPa for pressures. and 29 76 wt% LiBr for concentrations.Paper presented at the Twelfth Symposium on Thermophysical Properties, June 19–24, 1994. Boulder, Colorado, U.S.A.     

Substituted uracils as corrosion inhibitors for copper in 3% NaCl solution

Substituted uracils were tested as corrosion inhibitors of copper in 3% NaCl medium using electrochemical polarisation, impedance measurements and non-electrochemical techniques (weight loss, IR and UV-visible). This study permitted to follow the evolution of the inhibitory effect of the uracil derivatives, according to their substituents, on copper in 3% NaCl medium. Comparison of results showed that dithiouracil (DTUr) was the best inhibitor. The maximum inhibition efficiency reached 98% at 10⁻³ M. DTUr adsorbs on the copper surface according to the Frumkin isotherm model.     

具有偏差变元的Volterra型系统的周期正解

利用Mawhin重合度理论研究了一类具有偏差变元的Volterra型系统周期正解的存在性问题，得到了一个新的存在性定理。     

THE FLOW PRODUCED IN PARTICLE-SUSPENSION BY AN INFINITE ROTATING DISK:SERIES SOLUTION

To the flow produced in particle-suspension by a rotating disk of infinite extent,the asymptotic behavior at infinity is analyzed.A corresponding series solution is presented.It isshown that this approach yields widely valid solutions of high accuracy for all the cases in whichthat suction or weak injection at the disk surface exists.For the cases that strong injection or par-ticle-free band exists,the series method fails.     

聚电解质溶液分子热力学模型

<正>链状聚电解质由于是长链大分子又有很高的电荷密度,其溶液即使在极低的浓度下仍具有很强的负偏差,与Debye-Huckel理论预测的结果相去甚远。工程上使用的Manning模型认为聚离子的电荷密度有一临界值,当超过临界值时,反离子即凝聚在聚离子表面使其实际电荷密度降至临界值。Nagvekar等在该模型的基础上引入NRTL方程,以计及短程相互作用的贡献。Manning等的方法虽然有一定的物理意义,但临界值的确定缺乏可靠的根据。