小型天然气液化装置在我国天然气工业中的应用前景分析

天然气是一种洁净的能源,在国家环保安全和能源保障方面具有重要意义。液化天然气是天然气推广应用的重要形式。文中分析了小型天然气液化装置在我国天然气工业上游的零散气田和边远气田天然气、油田伴生气以及煤层气等领域和下游的液化天然气汽车和城市燃气调峰等领域的应用前景,指出小型天然气液化装置的应用将推动我国天然气工业的发展,为我国的能源结构调整和可持续发展发挥作用。     

二级轻气炮发射过程中前冲气体的初步研究

 在二级轻气炮发射过程中,靶室内的残存气体和绕行到弹丸前方的推进气体都有可能对实验结果造成影响。利用石英传感器测量并得到了二级轻气炮高速弹丸发射时前冲气体的压力信号,并计算得到了相应的压力。实验结果表明：二级轻气炮发射时确实存在前冲气体现象,但其压力幅值较小,约为10^-2 GPa量级,不会对高压物理实验的结果造成明显的影响。     

测量喷气Z箍缩负载的气流马赫数

 利用双压力传感器的方法测量了喷气Z箍缩负载的气流马赫数。测量得到的气流马赫数最高可达到4.25，它和定常计算的结果4.8很接近，这表明可以用定常计算来估算喷气Z箍缩中超声速喷嘴产生的气流马赫数。     

二维拉格朗日坐标系下气粒混合双向耦合对激波流场影响的计算

喷射颗粒与气体混合是内爆压缩领域的热点和难点. 针对喷射混合中的气粒双向耦合问题, 开展了理论建模、离散算法以及颗粒反馈对激波流场的影响研究. 建立了拉格朗日计算框架下的数学模型; 给出了耦合源项的离散算法; 开展了平面及汇聚构型条件下, 气粒双向耦合的数值模拟研究; 发现了颗粒反馈导致气体激波提速现象以及气区流场物理量分布形态的改变, 初步获得了量化分析结果. 本文建立的数学模型、计算方法和获得的新的物理认识, 为深入理解喷射混合现象、解决相关工程应用问题提供了重要理论支撑.     

Magnetic Flux Quantization of the Landau Problem

Landau problem has a very important application in modern physics, in which two-dimensional electron gas system and quantum Hall effect are outstanding. In this paper, first we review the solution of the Pauli equation, then using the single electron wave function, we calculate moving area expectations of the ideal 2-dimensional electron gas system and the per unit area’s degeneracy of the electron gas system. As a result, how to calculate the magnetic flux of the electron gas system is given. It shows that the magnetic flux of 2-dimensional electron gas system in magnetic field is quantized, and magnetic flux quantization results from the quantization of the moving area expectations of electron gas system.     

On the Stability of Ballooning Modes in the Boundary Layers of a Gas Insulated Plasma

In order to fulfill power density requirements in future steady-state fusion reactors the ion density in central parts must be of the order 10²⁰–10²¹–m^?3. In such systems high density neutral gas may surround the hot plasma, whether introduced on purpose or not, provided the neutral gas flux from the plasma is not continuously removed by external means. In gas insulated plasmas large density and pressure gradients will arise close to the boundaries on account of plasma neutral gas interaction effects. In this paper the stability of gravity driven ballooning modes in the boundary region is investigated. In particular, the coupling between plasma and neutral gas investigated in previous stability analysis is reconsidered. Also effects previously neglected for example the Nernst effect is taken into account.     

气相下材料真空放气性能的理论研究

气相下,材料表面气体分子的脱附速率会大大增加。文中对这方面的研究进行了总结,并应用分子动力学理论,从气相空间分子间的碰撞、气相空间分子与材料表面的碰撞、气相空间分子与材料表面的相互作用、材料表面气体分子的徙动、材料表面气体分子的脱附几个方面,从理论上研究气相下材料的真空放气性能。     

On the hypothesis of gas rotation in the magnetomechanical effect

This study continues a cycle of works published in Optika i Spektroskopiya (Optics and Spectroscopy) on the magnetomechanical effect in a gas discharge. It is devoted to the hypothesis of the appearance of a torque acting on an object placed in a gas discharge in a magnetic field and arising due to the momentum transfer from the rotating neutral gas. The velocities of gas rotation required for the formation of the observed moment of forces are estimated. Measurements of the velocities performed using laser Doppler anemometry are analyzed. The method of observing dust structures in a magnetic field to reveal gas rotation is justified. Corresponding experiments with the use of the method of optical visualization for the observation of plasma-dust structures are conducted. The experimental dependence ω(r) obtained for a liquidlike structure is not consistent with the hypothesis of the transfer of rotation from the gas. Additional observations of dust plasma upon tilting of the discharge tube in the gravitational field are conducted. It is found that, in this case, the structure shifts from the central region of the stratum to the periphery and the rotation ceases. Neither the analysis nor the experiments performed in this study are consistent with the hypothesis of gas rotation in the magnetomechanical effect. The results of the experiments with dust structures are of independent interest for the physics of dust plasma.     

Construction of the mass velocity profile for a rarefied molecular gas entrained by a rotating sphere taking into account thermophysical parameters of the gas

The problem of a sphere rotating in a molecular gas is solved in the isothermal approximation. The expression for the velocity of a rarefied molecular gas entrained by a sphere rotating in it is derived for sliding flow conditions taking into account the second-order correction in the Knudsen number. A generalization of the Boltzmann kinetic equation in the BGK model to the case of rotational degrees of freedom of gas molecules is used as the basic equation. The diffusive reflection model is employed as the microscopic boundary condition on the surface of the sphere. It is shown that this approach makes it possible to take into account the dependence of the gas velocity on the Prandtl number and gas temperature.     

Stress dependence of the chemical potential of adsorbates

It is shown that for a gas—alkali halide adsorption system, pressure applied to the substrate changes the contribution to the dispersion force that arises from the interaction of the gas with the substrate in the infrared region. This results in a corresponding stress-dependent change in the chemical potential of the gas.     

Features of radiation of the surface Stoneley wave by a harmonic force acting at the gas-solid interface

The solution is found for the problem of radiation of the surface Stoneley wave by a point harmonic force acting normally to the interface between uniform solid and gaseous half-spaces. We consider the case where the sound velocity in the gas is less than the Rayleigh-wave velocity on the surface of the solid. Expressions for the partial powers of the Stoneley wave radiated into the solid and the gas are obtained. The dependences of these powers on the parameters of the contacting media are analyzed. It is shown that if the velocities of the compressional and shear waves in the solid are significantly greater than the sound velocity in the gas, then almost all power of the Stoneley wave is concentrated in the gas. If the velocity of the Rayleigh wave in the solid half-space is close to the sound velocity in the gas, then the Stoneley-wave power radiated into the solid can be greater than the power radiated in the gas. __________ Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 51, No. 4, pp. 304–313, April 2008.     

Inverse effects of the gas feed positioning on sonochemistry and sonoluminescence

Purging of solutions to enhance sonochemical reactions is a common practice. A fundamental study combining sonoluminescence spectroscopy and sonochemical activity is adopted to study the effects of continuous Ar gas flow in the solution and of the position of the gas inlet tube on high-frequency sonolysis of aqueous solutions. It has been observed that neither sonochemical activity nor sonoluminescence intensity is controlled by the gas solubility only. Besides, the change in position of the gas inlet tube leads to opposite effects in sonoluminescence intensity and sonochemical activity: while the former increases, the latter decreases. Such an observation has never been reported despite sonochemical reactions have been carried out under different gas environments. Sonoluminescence spectroscopy indicates that more extreme conditions are reached at collapse with the gas inlet on the side, which could be explained by a more symmetrical collapse. Finally, it is shown in certain conditions that it is possible to favor the formation of some sonochemical products simply by positioning the gas inlet at different positions, which has practical significance in designing large scale sonochemical reactors for industrial applications.     

Numerical simulation of the translational nonequilibrium zone behind a shock-wave front

The translational nonequilibrium zone in a shock wave is considered for a gas consisting of light particles and a small addition of heavy particles. The gas is taken to be two-dimensional, and long-range forces are assumed to be absent. In the framework of this approximation, a program for molecular dynamics simulation of the gas is developed. It is applied to calculate a particle distribution function in the shock wave, to analyze the time evolution of the distribution function, and to study its dependence on the gas composition.     

On the theory of slowing down gracefully

We discuss the transport of a tracer particle through the Bose?CEinstein condensate of a Bose gas. The particle interacts with the atoms in the Bose gas through two-body interactions. In the limiting regime where the particle is very heavy and the Bose gas is very dense, but very weakly interacting (??mean-field limit??), the dynamics of this system corresponds to classical Hamiltonian dynamics. We show that, in this limit, the particle is decelerated by emission of gapless modes into the condensate (Cerenkov radiation). For an ideal gas, the particle eventually comes to rest. In an interacting Bose gas, the particle is decelerated until its speed equals the propagation speed of the Goldstone modes of the condensate. This is a model of ??Hamiltonian friction??. It is also of interest in connection with the phenomenon of ??decoherence?? in quantum mechanics. This note is based on work we have carried out in collaboration with D Egli, I M Sigal and A Soffer.     

Analytical Number Theory and the Energy of Transition of Bose Gas to Fermi gas. Critical Lines as Boundaries of Noninteracting Gas (an Analog of the Bose Gas in Classical Thermodynamics)

It is proved that certain distributions in the analytic number theory coincide with the Bose–Einstein distribution. The transition of the boson branch of the decomposition of an integer (with repeated summands) into the fermion branch (without repeated summands) is described in detail near a small value of activity. Analytic formulas for the energy of transition of Bose gas to Fermi gas are obtained in the three-dimensional case and the nine-dimensional case (diatomic molecule). The radius of the Bose gas “jump” in the transition to the Fermi gas is calculated. The relationship between the constructed concepts and thermodynamics is described based on the obtained experimental values of gas characteristics on critical lines.     

氘汽液变化过程的气化热及熵变计算

计算饱和液体的气化热通常是把该温度下的饱和蒸汽视为理想气体.但是氘的饱和蒸汽在临界温度Tc＝38.34 K以下作为理想气体计算气化热,得到的结果不符合一般规律.本文采用Clapeyron方程的微分形式和氘的汽液平衡方程,考虑氘由液态转变为气态的体积变化,计算得到20 K到38 K各温度对应的气化热和熵变,最后绘制出氘的饱和曲线.这种计算方法避免了两个近似:视氘饱和蒸汽为理想气体和忽略氘汽液转变的体积变化,提高了计算的精确度.     

Spectroscopic Investigation of the Separation of A Glow Discharge in an Argon-neon Mixture

The passage of a steady state electric current in a mixture of binary gases between apair of metal electrodes has been found to result in an enrichment of the minority constituent gas near the cathode and the majority gas in the vicinity of the anode (1–7). The study of the separation of the mixture of binary gases under the influence of a discharge current is important for practical applications in gas lasers and for obtaining very pure gas samples. Although extensive studies have been reported in various gas mixtures it seems relatively few have been made in argonneon^(2,3,5) and these were restricted to either low gas pressures or low discharge currents. In the present contri-bution a preliminary study of the cataphoresis separation is reported in a low proportion of argon in neon using spectro-scopic techniques.