Asymmetric dilation of multiwavelength cross-connect switches forlow-crosstalk WDM optical networks

We predict that, for wavelength division multiplexing optical-network applications, an asymmetrically dilated configuration of a 2×2 cross-connect is significantly better in terms of overall crosstalk when the levels of the bar-port crosstalk and the cross-port crosstalk are significantly different from each other, as is the case with optical-frequency filters which utilize grating-assisted coupling. As a verification, we present a simulation study with 2×2 polarization-diversified acousto-optic tunable filters. We present a recursive method to extend the principle of asymmetric dilation to larger-size cross-connect switches, and make a recommendation for an asymmetrically dilated 4×4 cross-connect configuration     

具有透明波导的量子阱半导体激光器及其光集成技术

本文论述了具有透明波导结构的量子阱半导体激光器及其光集成技术的其本原理及主要优点。尤其在实现高功率窄光束输出的光集成器件方面更显出其独特的优点。     

A model for evaluation and administration of security inobject-oriented databases

The integration of object-oriented programming concepts with databases is one of the most significant advances in the evolution of database systems. Many aspects of such a combination have been studied, but there are few models to provide security for this richly structured information. We develop an authorization model for object-oriented databases. This model consists of a set of policies, a structure for authorization rules, and algorithms to evaluate access requests against the authorization rules. User access policies are based on the concept of inherited authorization applied along the class structure hierarchy. We propose also a set of administrative policies that allow the control of user access and its decentralization. Finally, we study the effect of class structuring changes on authorization     

锂铁氧体纳米晶的磁性能研究

我们用ＰＥＧ凝胶法合成出的ＬｉＦｅ＿５Ｏ＿３纳米晶，用ＸＲＤ和ＴＥＭ观测其粒径和形貌。用振动样品磁强计考察其比饱和磁化强度σ＿ｓ，随粒径口变化，得到样品的σ＿ｓ随Ｄ的减小而下降。     

Acetylcholinesterase enhances neurite growth and synapse development through alternative contributions of its hydrolytic capacity, core protein, and variable C termini

Accumulated indirect evidence suggests nerve growth-promoting activities for acetylcholinesterase (AChE). To determine unequivocally whether such activities exist, whether they are related to the capacities of this enzyme to hydrolyze acetylcholine and enhance synapse development, and whether they are associated with alternative splicing variants of AChEmRNA, we used four recombinant human AChEDNA vectors. When Xenopus laevis embryos were injected with a vector expressing the synapse-characteristic human AChE-E6, which contains the exon 6-encoded C terminus, cultured spinal neurons expressing this enzyme grew threefold faster than co-cultured control neurons. Similar enhancement occurred in neurons expressing an insertion-inactivated human AChE-E6-IN protein, containing the same C terminus, and displaying indistinguishable immunochemical and electrophoretic migration properties from AChE-E6, but incapable of hydrolyzing acetylcholine. In contrast, the nonsynaptic secretory human AChE-I4, which contains the pseudointron 4-derived C terminus, did not affect neurite growth. Moreover, no growth promotion occurred in neurons expressing the catalytically active C-terminally truncated human AChE-E4, demonstrating a dominant role for the E6-derived C terminus in neurite extension. Also, AChE-E6 was the only active enzyme variant to be associated with Xenopus membranes. However, postsynaptic length measurements demonstrated that both AChE-E6 and AChE-E4 enhanced the development of neuromuscular junctions in vivo, unlike the catalytically inert AChE-E6-IN and the nonsynaptic AChE-I4. These findings demonstrate an evolutionarily conserved synaptogenic activity for AChE that depends on its hydrolytic capacity but not on its membrane association. Moreover, this synaptogenic effect differs from the growth-promoting activity of AChE, which is unrelated to its hydrolytic capacity yet depends on its exon 6-mediated membrane association.     

18Ni（350）马氏体时效钢的磁滞特性

采用双时效处理工艺研究了热轧１８Ｎｉ（３５０）马氏体时效钢的磁滞特性。结果表明，８２０℃·　ｈＡＣ＋（５９－６１０）·。ｈＡＣ＋５１０℃·。ｈＡＣ和８２０℃·　ｈＡＣ＋（６９０－７１０℃）·３ｈＡＣ＋１５０℃·３ｈＡＣ处理具有较高的磁滞性能，在对大量数据进行二元线性回归的基础上得出了１８Ｎｉ（３５０）马氏体时效钢磁滞特性的分段关系式。     

广东省伴生放射性矿资源利用过程辐射水平调查

为加强伴生放射性矿物资源开发利过程中放射性环境管理 ,防治放射性污染 ,对广东省几个大型伴生矿(包括稀土矿、钽铌矿和铅锌矿 )资源利用 (开采、冶炼、加工 )过程中天然放射性核素的污染现状进行了调查。调查结果表明 :稀土矿中独居石 ,天然放射性核素含量最高 ,2 3 8U、2 3 2 Th、2 2 6Ra的含量分别为 3.5 1× 1 0 4、1 .74× 1 0 5、4 .8×1 0 4Bq/kg,其冶炼废渣中核素的含量分别为 5 .1 0× 1 0 5、6 .38× 1 0 6、1 .5 2× 1 0 6Bq/kg。稀土选冶厂周围陆地环境 γ射线的空气吸收剂量率比一般地区的高。     

连续小波变换在多元函数空问中的应用

使用连续小波变换讨论了某些偏微分方程和相应的积分方程之间的关系．使用连续小波变换能够将这些偏微分方程变换成相应的积分方程，这些偏微分方程与相应的积分方程不仅在弱收敛意义下是等价的，而且在范数收敛意义下也是等价的．     

纺丝组件漏浆原因分析

通过对纺丝组件工艺对比调试,分析了纺丝组件消耗材料对纺丝组件漏浆的影响,指出了纺丝组件漏浆的主要影响因素。     

纳米TiO_2半导体催化活性的研究进展

纳米TiO2半导体催化技术具有广阔的应用前景,近年来半导体光催化已成为功能陶瓷材料、光化学、环境保护、生物技术等领域的研究热点之一。本文简要介绍了近年来国内外纳米TiO2半导体光催化剂的研究进展,主要包括纳米TiO2光催化剂的作用机理及结构的影响;提高催化活性的方法,指出了表面贵金属沉积、复合半导体、金属离子掺杂和表面光敏化是提高催化活性和催化效率的有效途径。