Hulthen势与谱生成代数

本文将Hulthen势场中的S波径向方程作适当的变量变换、使其可用so(2.1)李代数求解;进而通过倾斜变换引入附加参数ω以改善解的收敛性,并给出了迭代求解的全部计算公式。     

Beyond Einstein's radiation theory

Einstein's radiation mechanism is generalized to account for the possibility of population inversion by placing a nonlinear bound on the growth of an unstable perturbation. The nonstationary linear mechanism of relaxation to blackbody radiation below threshold is studied. The nonstationary photon distribution is the negative binomial distribution, and casting it as a law of error, for which the most probable value is the mean value, gives the expression for the statistical entropy. The second law yields a nonequilibrium generalization of Planck's radiation law. The nonlinear mechanism leading to the transformation from the negative binomial probability distribution, for chaotic light, to a Poisson probability distribution, for coherent light, is then analyzed. A criterion for lasing is given in terms of the chemical potential of radiation which is compared to the inequality for the transition from quantum to classical statistics.     

Nonlinear optical properties in a quantum well with the hyperbolic confinement potential

We have performed theoretical calculation of the nonlinear optical properties in a quantum well (QW) with the hyperbolic confinement potential. Calculation results reveal that the transition energy, oscillator strength, second-order nonlinear optical rectification (OR), geometric factor and nonlinear optical absorption (OA) are strongly affected by the parameters (α,σ) of the hyperbolic confinement potential. And an increment of the parameter α reduces all these physical quantities, while an increment of the parameter σ enhances them, but not for geometric factor. In addition, it is found that one can control the optical properties of QW by tuning these parameters.     

气体扩散方程解析解及在测定分子间势能的应用

设计了一新颖的分子动理论实验装置,根据求解在约束条件下的气体扩散方程的解析解和气体分子在升华时会对容器底部产生作用力的特点,设计了一种新颖简单的实验器材来测量分子间相互作用的势能,其实验曲线符合理论数据,误差分析后的补偿曲线所得结果可较为精确地与理论结果吻合。本实验常温下即可进行,且精度较高,适合快速材料性质测定及大学物理教学,以解决大学物理演示实验课关于学气体动理论的实验数量较少,且往往只涉及对热学微观过程的宏观模拟,而很少涉及气体动理论的实验,导致学生学习不够深入的问题。有利于学生对分子运动学问题的深入探索。     

Relationship between the 2-body Parameters of the Biswas-Hamann and the Bauer-Maysenholder-Seeger Potential Functions

A theoretical relation between the Bauer-Maysenholder-Seeger (BMS) and the Biswas-Hamann (BH) potential function has been developed herein for the case of 2-body interaction. By equating derivatives of these two potential functions for the 2-body part, a loose form of BMS is expressed in terms of BH parameters with a scaling factor. The validity of the developed parametric relationships has been graphically demonstrated, and the suitability discussed with reference to the extent and direction of bond distortion.     

Thickness and local field effects on energy transfer rate in coupled quantum wells system: Linear regime

We investigate theoretically the dependence of energy transfer rate in Double-Quantum-Well system on the well thickness by using the balance equation formalism. Also, by including the local field correction in our calculations through the zero- and finite-temperature Hubbard approximations, we study the effect of the short-range interactions on the energy transfer phenomenon. Calculations consider both the static and dynamic screening approximations. Our numerical results predict that the energy transfer rate increases considerably by increasing the layers' thicknesses and by taking into account the short-range interactions, as well.     

First-principles study of the (0 0 1) surface of cubic SrZrO3

Density functional calculations have been used to investigate the (0 0 1) surface of cubic SrZrO₃ with both SrO and ZrO₂ termination. Surface structure and electronic structure have been obtained. The SrO surface is found to be similar to its counterpart in SrTiO₃, while there are marked differences between the ZrO₂ and TiO₂ terminations in SrZrO₃ and SrTiO₃, respectively, concerning surface relaxation and rumpling. For the ZrO₂-terminated surface of SrZrO₃, the covalency of the interaction between the outmost Zr and the O beneath is enhanced as a result of their bond contraction. The band gap reduction and the presence of the surface states are also discussed in relation with the behavior of the electrostatic potential.     

Dilatonic Dark Energy Model with Late Time de Sitter Attractor

Based on Weyl-scaled induced gravitational theory, we regard dilaton field in this theory as a candidate of dark energy. We construct a dilatonic dark energy model and its phantom model, that admit late time de Sitter attractor solution. When we take the potential of dilaton field as the form which has been studied in supergravity model and the famous Mexican hat potential , we show mathematically that these attractor solutions correspond to an equation of state ω = −1 and a cosmic density parameter Ω_σ = 1, which are important features for a dark energy model that can meet the current observations.     

Ultrasonic technology for enhanced oil recovery from failing oil wells and the equipment for its implemention

A new method for the ultrasonic enhancement of oil recovery from failing wells is described. The technology involves lowering a source of power ultrasound to the bottom of the well either for a short treatment before removal or as a permanent placement for intermittent use. In wells where the permeability is above 20 mD and the porosity is greater than 15% ultrasonic treatment can increase oil production by up to 50% and in some cases even more. For wells of lower permeability and porosity ultrasonic treatment alone is less successful but high production rates can be achieved when ultrasound is applied in conjunction with chemicals. An average productivity increase of nearly 3 fold can be achieved for this type of production well using the combined ultrasound with chemical treatment technology.