WKB近似下的Fourier衍射成象方法

对于介质目标微波衍射成象，本文引入了ＷＫＢ近似来模拟目标内部总场。基于这种近似，我们导出了Ｆｏｕｒｉｅｒ衍射公式，并采用了广义滤波逆传播方法由目标空间谱实现目标特性的重建。计算机模拟结果表明采用ＷＫＢ近似重建目标特性较Ｂｏｒｎ近似有明显改善。     

Effective electromagnetic and chiral parameters of chiral composite material

The effective parameters of chiral composite are studied using a simple model, that is, randomly oriented non-interacting wire helices embedded in a nonchiral host medium. It is found that both the effective permittivity ? and permeability μ are independent on the handedness of the chiral objects while the effective chirality admittance ξ is dependent. It is also found that when the ratio of the radius of the chiral helix to its pitch is about 0.23, maximum chirality admittance is achieved. The effective parameters of equichiral sample are also discussed.     

低温粉碎系统中旋风分离器设计

旋风分离器是一种应用离心力进行粉体分离的设备。低温粉碎系统应用它分离粉体并起集粉作用。它的效率决定了物质回收率。本文从离心加速度与重力加速度的比值，筒体的高低，筒体直径，进口速度叙述对分离器效率的影响。着重叙述筒体直径确定方法，以及我们设计造长筒形旋风分离器的具体结构和令人满意的试验结果。     

Alkali-metal Na Adsorption and Promoted Oxidation on Si(100)2×1 Surface

The alkali-metal Na adsorption on Si(100)2×1 surface and its promoted oxidation and Si oxidegrowth have been investigated by means of thermal desorption,work function,Auger electronspectroscopy and photoemission electron spectroscopy.The experimental data showed that therewas a new state,interface electron state,near the Fermi level after the deposition of Na atoms.It wasfound that the presence of Na always caused an increase of the oxygen initial uptake whereas thepromotion of Si oxide growth was observed only at the coverage of Na greater than 0.5 ML.A newmechanism of Na-promoted Si oxide growth is suggested in this paper.     

Electrical properties and positron annihilation study of (Ba<Subscript>1−<Emphasis Type="Italic">x</Emphasis></Subscript>Ho<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>)TiO<Subscript>3</Subscript> ceramics

DC resistivity, dielectric constant, dielectric loss and positron annihilation spectra of (Ba_1−x Ho _x )TiO₃ ceramics have been measured as a function of holmium concentration x. It has been found that the DC resistivity of (Ba_1−x Ho _x )TiO₃ is strongly dependent on the Ho content: it decreases three orders of magnitude and reaches a minimum at x = 0.4%. Doping with 0.6% holmium increases the permittivity of BaTiO₃ by approximately three times (from ∼1,300 to ∼4,000), with only a slight increase in the corresponding dielectric loss. The local electron density and defect concentration estimated using positron annihilation technique conforms well to the features found in the dielectric and resistivity measurements. The results have been discussed in terms of a mixed compensation model.     

基于数字运算的PSD调理电路设计

介绍了基于数字运算的PSD调理电路思想及具体线路构造,该电路避免了模拟运算的缺陷,提高了精度和可靠性.     

光声耦合与光子Cooper对

文中研究了光声耦合所导致的光子Cooper对的形成机制，计算了光子Cooper对的能隙（0.01eV）和尺度（10^-5m)以及内禀角动量（奇数），并简要讨论了几十开低温下介质中光的超流效应的可能性。由于在低温下， 光子Cooper对不容易受到热运动的激发，因此有可能存在光的超流现象。     

一种改进的基于OOC的MWOOC

从理论上分析了一种基于光正交码（OOC）的多波长光正交码（MWOOC）的性能。给出了一种改进的基于OOC的MWOOC，并且蛤体分析了它的性能。与原MWOOC比较，改进的MWOOC的误码率性能基本相同，但码字数增加很多。     

纳米超晶格热电材料的研究进展

随着热电材料制备技术和性能研究的发展，纳米超晶格热电薄膜已受到人们的关注，简要介绍了有关纳米超晶格热电材料的结构、热电机理及制作技术，并指出了存在的问题和可能的发展方向。