Simplified and complex modeling of self-sustained discharge-pumped,Ne-buffered XeCl laser kinetics

Two simple kinetic models of a Ne-buffered XeCl laser discharge are presented based on different simplifications of the chemical kinetics of a complex model that recently appeared in the literature. When applied to the study of a small-volume XeCl laser, the results of both simple and complex models are in satisfactory agreement with the experiments. Shifting to a larger-volume laser, both models show problems due to loss of stability of the discharge. A one-dimensional modelling is performed, and it is found that different assumptions on the kinetics of the NeXe⁺ ion in the discharge lead to completely different results as regards the effect of a preionization-triggered instability.     

等离子体中的迁移系数

从等离子体动力学方程出发,采用玻尔兹曼碰撞项,在粒子分布函数偏离麦克斯韦分布甚小的情况下,作三级矩近似得到了等离子体迁移方程组。迁移方程组中忽略时间微分项后,得出了电子-离子等离子体的张量形式迁移系数,以及与磁场方向成平行(∥)、垂直(⊥)和交叉方向的迁移系数。导出的结果和文献[1]采用朗道碰撞项得出的结果进行了比较。结果表明,迁移系数和等离子体参数的依赖关系是一致的,但对磁场B和离子电荷Z_i值取定时,个别迁移系数要差一倍。此外,导出的迁移系数形式比文献[1]的要简单些。     

Some New Results on Key Distribution Patterns and Broadcast Encryption

This paper concerns methods by which a trusted authority can distribute keys and/or broadcast a message over a network, so that each member of a privileged subset of users can compute a specified key or decrypt the broadcast message. Moreover, this is done in such a way that no coalition is able to recover any information on a key or broadcast message they are not supposed to know. The problems are studied using the tools of information theory, so the security provided is unconditional (i.e., not based on any computational assumption).In a recent paper st95a, Stinson described a method of constructing key predistribution schemes by combining Mitchell-Piper key distribution patterns with resilient functions; and also presented a construction method for broadcast encryption schemes that combines Fiat-Naor key predistribution schemes with ideal secret sharing schemes. In this paper, we further pursue these two themes, providing several nice applications of these techniques by using combinatorial structures such as orthogonal arrays, perpendicular arrays, Steiner systems and universal hash families.     

GaAs／AlGaAs发光二极管列阵场分布特性的电光测量

应用一种新颖的无损伤测量技术－连续波电光检测法（ＣＷＥＯＰ）对ＧａＡｓ／ＧａＡｌＡｓ单异质结发光管列阵电场分布进行了扫描测量。实验结果反映了器件内电流注入的方向和载流子扩展情况；通过比较各单元电场分布，反映器件发光均匀性。文中详细介绍了测量原理、实验装置和实验结果及讨论，最后用计算机对电场分布作了模拟计算并与实验结果进行了对照。     

一般非均匀凸介质迁移算子本征值的分布

本文讨论一般非均匀凸介质所确定的迁移算子的本征值的分布问题，利用Ｈｉｌｂｅｒｔ空间的Ｈ算子理论，完整地解决了一般非均匀凸介质中迁移算子本征值的分布问题，若｛λｎ｝ｎ＝１＾∞是迁移算子本征值的一种计数，我们证明了Σ↓ｎ＝１↑∞ｅ＾６Ｒｅλｎτ〈＋∞，其中τ是粒子的最大逃逸时间，并对本征值的发散程度以及本征值的个数函数作了相应的讨论。     

指数型寿命数据中异常值的检验

本文讨论了在指数型寿命数据中,对同时存在的异常大数据和异常小数据的检验方法,给出了一个明确的判别标准,并以一例说明其应用。     

Number albedo measurements from stratified layers of iron,concrete and aluminium

A layer of stratified combination composed of selected radiation shielding materials acquires better shielding property. Albedo is used in such measurements as an integral measure ofγ-ray scattering. The stratified slabs of alternating heterogeneous layers have been found to have a virtual homogeneous property with a definite effective atomic number. The angular distribution of back-scattered photons as well as the total number albedo values for iron, aluminium and concrete in stratified combination for 662 keV and 1250 keV photons are reported.     

Interpolatory integration rules and orthogonal polynomials with varying weights

We investigate which types of asymptotic distributions can be generated by the knots of convergent sequences of interpolatory integration rules. It will turn out that the class of all possible distributions can be described exactly, and it will be shown that the zeros of polynomials that are orthogonal with respect to varying weight functions are good candidates for knots of integration rules with a prescribed asymptotic distribution.Research supported by the Deutsche Forschungsgemeinschaft (AZ: Sta 299/4-2).     

氢化丁苯共聚物结构的核磁共振波谱表征Ⅰ.13C谱带的归属

本文分别用JEOL FX-90Q和Bruker AM-300波谱仪测定了氢化聚丁二烯和氢化丁苯共聚物的¹H,¹³C-NMR谱,得到了分辨率较高的谱图和新的结构信息。借助DEPT技术确定了各谱带的CH或CH₂类型。利用Grant-Paul和Lindeman-Adams介绍的化学位移经验计算公式,考虑苯基对α、β和γ碳原子的影响,计算了各种三单元序列中有关碳原子的化学位移。对脂肪碳部分的28组谱带重新进行了归属。化学位移计算值与实测值基本相符,并得到了不同组成的模型聚合物¹³C-NMR谱的各谱带强度变化规律的验证。