Nonlinear MHD Kelvin-Helmholtz instability in a pipe

Nonlinear MHD Kelvin-Helmholtz (K-H) instability in a pipe is treated with the derivative expansion method in the present paper. The linear stability problem was discussed in the past by Chandrasekhar (1961)^[1] and Xu et al. (1981).^[6]Nagano (1979)^[3] discussed the nonlinear MHD K-H instability with infinite depth. He used the singular perturbation method and extrapolated the obtained second order modifier of amplitude vs. frequency to seek the nonlinear effect on the instability growth rate γ. However, in our view, such an extrapolation is inappropriate. Because when the instability sets in, the growth rates of higher order terms on the right hand side of equations will exceed the corresponding secular producing terms, so the expansion will still become meaningless even if the secular producing terms are eliminated. Mathematically speaking, it's impossible to derive formula (39) when γ ₀ ² is negative in Nagano's paper.^[3]Moreover, even as early as γ ₀ ² → O⁺, the expansion becomes invalid because the 2nd order modifier γ₂ (in his formula (56)) tends to infinity. This weakness is removed in this paper, and the result is extended to the case of a pipe with finite depth. Theproject is supported by the National Natural Science Foundation of China.     

磁场中正柱非线性理论的自洽解

本文讨论磁场中中等低气压弧光放电与辉光放电的正柱理论。文献[1]是给定放电中间参数后,假定中性气体运动,研究放电现象.本文仍假定中性气体运动,但给出初始放电参数,补充两个积分关系,建立了初始放电参数与中间参数的关系。给出这个问题完整的数学提法。用数值方法求解。文献[1]相当于第一次迭代。结果表明,这种改进是必要的.     

Electronic structure and optical property of boron doped semiconducting graphene nanoribbons

We present a system study on the electronic structure and optical property of boron doped semiconducting graphene nanoribbons using the density functional theory. Energy band structure, density of states, deformation density, Mulliken popular and optical spectra are considered to show the special electronic structure of boron doped semiconducting graphene nanoribbons. The C—B bond form is discussed in detail. From our analysis it is concluded that the Fermi energy of boron doped semiconducting graphene nano...     

Distribution threshold values of CaCl_2 onto the 10X-zeolite and macro-pore silica gel

The calcium chloride used for adsorption separation of ammonia is promising for its large adsorptive capacity and lower desorption temperature,but difficult to develop because of the liable expansion,lump and chip in the adsorption/desorption process.Composite adsorbents made by monolayer dis-persion of calcium chloride onto carriers with high surface areas exhibit better adsorptive capacity and stability.Several models were developed to confirm the maximum monolayer dispersion capacity of calcium chloride ...     

A self-consistent solution for nonlinear theory of the positive column in a magnetic field

Only the electron and ion gases were taken into account in all previous theories of the positive column of intermediately-low-pressure arc discharge with or without the longitudinal magnetic field, while the motion of neutral gas was neglected. In 1982, the authors^[1] presented a nonlinear theory of a positive column which indicated that the rotating velocities of neutral gas and ion gas were nearly equal, and the motion of neutral gas could not be ignored. They further discussed the problem of validity of Bohm's criterion. However, some of the parameters with which the computation was worked out in Ref. [1] were not correlated to the initial discharge parameters. In the present paper, two integral relations are supplemented, so that a complete mathematical formation of the problem is given. A convergent numerical solution is obtained by iteration and the solution of Ref. [1] turns out to be the first iteration approximation. It is shown that both functions and parameters obtained by self-consistent solution differ significantly from those obtained in the first iteration approximation. According to this paper the computation can be conducted when the initial discharge parameters are given, so this method could have certain practical applications.     

大气层外核爆炸X射线辐射场特性研究

X射线被认为是大气层外反导栏截武器的主要破坏因素。在航天器结构材料的辐射损伤计算中,需要核爆炸X射线辐射场的数学模式。从Planck黑体谱出发,提出按温度梯度分层的归一化黑体谱组合模式,给出X射线的释放能量及辐射脉冲,从而建立了大气层外核栏截X射线辐射场特性的数学模式。     

The development of a chemical engineering data base

The organization of a scientific data-base system and a management system is outlined. The chemical engineering data base includes seven separate data bases. Examples of applications of the inorganic thermochemistry data base are given for the production of phase diagrams and simulation of the QSL method for lead smelting. Interfacing of the various units is discussed.     

无机热化学数据库中卤化物高温熵的计算机预报

在W. M. Latimer估算化合物标准熵的方法的基础上,建立了卤化物高温熵的计算机预报方法。作为试验,未参加训练的18个卤化物高温熵的预报值与实验值作了对照,其偏差均小于20焦耳/度·摩尔,即与若干卤化物标准熵的实验误差相近。     

电流分布对直圆柱等离子体不稳定性发展率的影响

本文的结果是:在直圆柱等离子体的情形,提高βp并未使扭曲模不稳定性变得更坏。对m=1的扰动,趋中心的轴向电流分布比起较平坦的分布来说不稳定性发展率要大,即稳定性反而变坏。当m=2时,情况正相反,这和文献[1,8]的结果一致。计算结果表明,角向电流的不同分布对不稳定性发展率的影响不大。