Solvothermal Synthesis and Crystal Structure of a Layered Thioantimonate(Ⅲ) [C4H9NH3]2Sb4S7

An inorganic-organic hybrid thioantimonate(Ⅲ) [CH3(CH2)3NH3]2Sb4S7 1 with layered structure was synthesized by solvothermal method.1 crystallizes in the triclinic system, space group P with a = 7.0124(11), b = 11.919(2), c = 14.879(3) (A), α = 108.791(3), β = 102.441(3), γ = 92.846(2)o, V = 1140.1(3) (A)3, Mr = 859.71, Z = 2, Dc = 2.504 g/cm3, μ= 5.324 mm-1, F(000) = 804, S = 1.013, the final R = 0.0297 and wR = 0.0618 for 3534 observed reflections with I＞2σ(I). 1 consists of [C4H9NH3] cations and two-dimensional [Sb4S7]n2n-anion which is composed of three SbS3 trigonal pyramids and one SbS4 unit joined by sharing common corners. The anionic layers are stacked perpendicularly to the c axis of the unit cell forming two-dimensional channels between the layers. The [C4H9NH3] cations interdigitate in a bilayer and reside in the 2D channels leading to a sandwich-like arrangement of the anion and cations.     

我国科普资源共享发展战略研究

我国科普资源共享在我国科普工作中具有基础性、牵动性的地位。本文在深入调研基础上,分析了公共科普资源共享的发展现状、工作难点和存在问题,探讨提出了科普资源共享工作下一步发展的指导思想、战略目标及工作原则,并有针对性地提出了下一步工作的若干建议。     

大学化学课程的混合式教学实施与探索

为更好地建设精品资源共享课,提高人才培养质量,结合哈尔滨工业大学"大学化学国家精品课程"现有改革成果,初步尝试了面授加视频的混合式教学,探讨了在实践过程中取得效果和反映出的问题,并为混合式教学的推广实施提出了建议。旨在促进未来大学化学课程的在线教育发展,提高教学效果。     

基于Shibboleth的校际跨域认证研究与实现

分析比较跨域认证相关技术,基于Shibboleth的跨域认证系统最适合用于校际间的身份认证,实现资源和服务的单点登录和共享,因此通过对Shibboleth认证机制的改进,实现校际间的LDAP认证方式、关系型数据库认证方式和SAML2认证方式的认证集成.最后,在跨校认证基础上构建资源共享应用和全局服务应用.     

没有SDC的(t，n)门限秘密共享方案

利用椭圆曲线离散问题对数问题的难解性,给出了基于椭圆曲线密码体制的(t,n)门限秘密共享方案。基于门限秘密共享方案一般分为需要SDC和不需要SDC两类,在分布式环境下,一个被所有成员信任的SDC并不存在,不需要SDC的门限秘密共享方案的安全性得到很大的提高,该方案中由组成员共同生成群公钥和私有密钥。并给出了当新成员加入时,无SDC下的周期密钥分片的更新方案。还给出了一个本方案数据实例,最后对本方案的安全性进行了分析。     

基于非最大纠缠的五粒子Cluster态的高效量子态共享方案

本文提出了一个新的未知量子态共享方案,使用一个非最大纠缠的五粒子Cluster态作为量子通道来实现任意两粒子未知量子态的共享. 即就是发送方（Alice）,接收方（Bob）和控制方（Charlie）共享一个非最大纠缠的五粒子Cluster态. 与以前传统方案不同,在本方案中发送方引入一个辅助粒子,并对其手中的粒子进行正交完备基测量,而接收方不需要引入辅助粒子,只需要执行适当的幺正操作,即可以方便的完成信息的顺利接收. 控制方通过对自己手中的粒子做单粒子投影测量来控制和协助通信双方,使得任意两粒子的未知量子态共享方案得以成功实现. 关键词： 量子态共享 五粒子Cluster态 正交完备基测量 单粒子投影测量     

On results of G. Brosch and T.C. Alzahary

We prove a uniqueness theorem for two non-constant meromorphic functions sharing three values which improves a recent result of T.C. Alzahary. As a consequence of our main result we also improve a theorem of G. Brosch.     

美国线路共享政策的实施与现状

线路共享指的是，用户除了从自己归属的本地电话公司（ILEC）以外还能选择从其它运营公司（主要指CLEC）为自己提供数据业务，并且不必安装第二条电话线。线路共享为现有电话线路上开展数据业务竞争铺平了道路，它在美国被视作能否成功开放DSL市场的关键因素。本文对美国针对DSL发展问题出台线路共享政策以及线路共享政策出台后的实施状况加以报道。对于我国制定线路共享政策和实施管理提供参考。     

On the Contrast in Visual Cryptography Schemes

A visual cryptography scheme is a method to encode a secret image SI into shadow images called shares such that certain qualified subsets of shares enable the ``visual' recovery of the secret image. The ``visual' recovery consists of xeroxing the shares onto transparencies, and then stacking them. The shares of a qualified set will reveal the secret image without any cryptographic computation. In this paper we analyze the contrast of the reconstructed image in k out of n visual cryptography schemes. (In such a scheme any k shares will reveal the image, but no set of k-1 shares gives any information about the image.) In the case of 2 out of n threshold schemes we give a complete characterization of schemes having optimal contrast and minimum pixel expansion in terms of certain balanced incomplete block designs. In the case of k out of n threshold schemes with we obtain upper and lower bounds on the optimal contrast. Received 27 September 1996 and revised 13 February 1998     

Batch processor sharing with hyper-exponential service time

We study the Processor Sharing queueing model with a hyper-exponential service time distribution and Poisson batch arrival process. In the case of the hyper-exponential service time distribution we find an analytical expression for the expected conditional response time function and obtain an alternative proof of its concavity with respect to the service time.