风沙运动的研究进展和发展趋势

对风沙运动的研究给出较为全面、系统的总结和介绍，对现有的各种理论模型进行对比和评介，并提出了自己的观点。最后，对风沙运动研究的发展趋势作了展望和预测。

红外光子牵引探测仪中P型锗元件最佳参数的研究

本文对红外(10.6μm)光子牵引探测仪中P型锗的吸收系数与电阻率的关系进行了讨论。导出了P型锗对10.6μm光的吸收系数的简便公式。进而根据理论分析,给出了光子牵引探测仪锗棒的电阻率、长度及截面等最佳参数的选取原则和结果。利用文章中的公式可以很方便地计算锗元件参数和响应率。本文对光子牵引探测仪的制作有一定的指导意义。

Influence of liquid bridge volume on the onset of oscillation in floating-zone convection .2. Numerical-simulation

The onset of oscillation in the floating zone convection driven by the gradient of surface tension was studied numerically for an unsteady and two-dimensional model, and studies were concentrated on the influence of liquid bridge volume on the onset of oscillation in comparison with the experimental results in the Paper I. The numerical results agree with the experimental ones presented in the previous paper, in which the distributions of critical applied temperature difference depending on the volume of liquid bridge and a gap range of liquid volume in marginal stability curve were obtained.

Steady axi-symmetrical thermocapillary motion of a short melting column

This paper deals with the steady axi-symmetric thermo-capillary motion in a short meltingcolumn.with the assumptions that the Marangoni number M<<1, the Reynolds number Re<<1 andthe capillary number C<<1, at the leading order, the solutions of the problem are obtained inthe form of series. For two kinds of typical cases, symmetric and anti-symmetric distributionof air temperature, the numerical calculations are made. The results describe the effect ofendwalls on thermo-capillary flow.

The piston model of coronal transients

In the present paper, the piston model of the coronal transient (see Hu. 1983a, b is discssed in detail, and the quantitative results of unsteady gasdynamics are applied to the coronal transient processes. The piston model explains the major features of the transient observations, such as the density profile, the geometric configuration, the kinetic process and the classifications of the coronal transient. Based on the idea of piston model, the bright feature and the dark feature of the transient are the gasdynamical response of the dense plasma ejecting into the corona, and associate with the compressed and rarefied flows, respectively. The quantitative results show that the density increment in the compressed region and the density decrement in the rarefied region are one order of magnitude larger and smaller, respectively, to the density in the quiet corona, it agrees quantitatively with the observations, and both the bright feature and dark feature are explained at the same time.

The non-axisymmetrical configuration of a large-scale solar and stellar magnetic field

in the corona, consisting of an eruptive prominence and/or a magnetic flux region (loop or arcade, or blob) in front of the prominence. Ahead of the piston, there is a compressed flow, which produces a shock front. This high-density region corresponds to the bright feature of the transient. Behind the piston, there is a rarefaction region, which corresponds to the dark feature of the transient. Therefore, both the bright and dark features of the transient may be explained at the same time by the dynamical process of the moving piston.

Influences Of Precursor Constitution And Processing Speed On Microstructure And Wear Behavior During Laser Clad Composite Coatings On Gamma-Tial Intermetallic Alloy

The effects of constitution of precursor mixed powders and scan speed on microstructure and wear properties were designed and investigated during laser clad gamma/Cr7C3/TiC composite coatings on gamma-TiAl intermetallic alloy substrates with NiCr-Cr3C2 precursor mixed powders. The results indicate that both the constitution of the precursor mixed powders and the beam scan rate have remarkable influence on microstructure and attendant hardness as well as wear resistance of the formed composite coatings. The wear mechanisms of the original TiAl alloy and laser clad composite coatings were investigated. The composite coating with an optimum compromise between constitution of NiCr-Cr3C2 precursor mixed powders as well as being processed under moderate scan speed exhibits the best wear resistance under dry sliding wear test conditions. (C) 2008 Elsevier Ltd. All rights reserved.

甲烷团簇纯库仑爆炸的离子平均动能

利用一简单的经典静电模型研究了甲烷团簇纯库仑爆炸情况下产生的离子平均动能。研究表明，甲烷团簇爆炸后离子获得的平均动能和离子的初始平均静电势能的比值，与团簇的尺寸大小无关。这意味着在甲烷团簇纯库仑爆炸近似下，不必使用分子动力学模拟，离子获得的动能可以通过这一比值以及离子的初始静电势能进行估算。给出了不同碳离子价态下的离子平均动能和其初始平均静电势能的比值。

发射和接收光束同时开关的激光测距法

采用同一电光器件对发射和接收光束同时开关的原理，提出了一种新颖的激光测距方法。光源发出的连续激光被待测目标反射后，往返两次通过光源端的电光晶体，在晶体上施加边沿急速变化的电压，利用其高速响应的开关特性，同时对往返光线产生影响，截取出一段包含激光往返待测距离所需时间信息的光强变化曲线。实验中利用雪崩管电路实现了纳秒级的高压上升沿，并利用单轴晶体的双折射和全内双反射性质，用特殊结构的单块LiNbO3晶体实现了该方法的测距装置。示波器分析的实验结果验证了该方法的可行性，从而为激光测距开拓了一种新的思路。

中国古代玻璃的起源--中国最早的古代玻璃研究

研究了西汉（公元前200年）以前不同地区的最早的中国古代玻璃．古玻璃样品出土于新疆维吾尔自治区、湖北省、湖南省、四川省、云南省、广东省和贵州省等地．用质子激发X光荧光技术、能量分散X光荧光技术和电感耦合等离子发射光谱等方法测定了玻璃的化学成分．这些古玻璃样品的化学成分属于以下玻璃系统：Na2O（K2O）-CaO—SiO2（K2O：Na2O〈1），K2O（Na2O）-CaO—SiO2（K2O：Na2O〉1），K2O—SiO2和BaO—PbO—SiO2．从考古和历史学观点讨论了这些最早的中国古代玻璃的起源，指

Output beam quality of edge pumped planar waveguide lasers with confocal unstable resonators

Output beam quality of edge pumped planar waveguide lasers with confocal unstable resonators is investigated by diffraction methods, taking into account gain saturation, asymmetric pumping, and beam interaction. The influences of pumping uniformity, doping concentration, cavity length and effective Fresnel number are analyzed with respect to output beam quality and pumping efficiency. It is found that good beam quality and high efficiency can be obtained with asymmetric pumping and optimized negative branch confocal unstable resonators. (c) 2005 The Optical Society of Japan.

Structure and thermal stability of novel fluorophosphate glasses

A systematic investigation on glass formation in the PbF2-InF3-BaHPO4 ternary system has been carried out. These glasses have characterized by IR spectra, Raman spectra and differential thermal analysis. The results show that the structure of these glasses is mainly affected by BaHPO4 and InF3 contents. With decreasing BaHPO4 content, the glass structure gradually transforms from metaphosphate to polyphosphate. When InF3 content is low, it mainly acts as network modifier, when its content is high; it enters glass matrix and forms In(O,F)(6) groups connecting the polymerized phosphorus oxygen species. PbF2 mainly acts as network modifier in this system. Systematic variations of the glass transition temperature and the thermal stability index agree well with these results. The most stable glass with Delta T = 230 degrees C and S = 21.79 K is obtained. (c) 2004 Elsevier B.V. All rights reserved.

Physical and thermal properties of P2O5-Al2O3-BaO-La2O3 glasses

The physical and thermal properties Of P2O5-Al2O3-BaO-La2O3 glasses were investigated. The effects of glass compositions on the transition temperature, thermal expansion coefficient, density, hardness and refractive index of glasses were studied. The highest hardness of the glasses is 4143.891 MPa and the lowest thermal expansion coefficient of the glasses is 71.770 x 10(-7)/&DEG; C. A phosphate glass with high mechanical strength and good thermal characteristic is obtained.