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.     

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 ...     

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     

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.     

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。     

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.