透析3G在中国面临的重重困局(1)--牌照与标准选择

探讨了中国3G牌照何时发放、发放数量、牌照与标准是否捆绑、3G产业链如何搭建、频率如何分配、市场容量和终端等问题，并对此提出了建设性的意见。     

Influence of third monomer on the crystal phase transition behavior of ethylene-tetrafluoroethylene copolymer

Crystal phase transition between the low- and high-temperature phases has been investigated for ethylene (E)-tetrafluoroethylene (TFE) alternating copolymer (ETFE) containing the third monomeric species by the temperature dependent measurements of wide-angle X-ray diffraction (WAXD) and small-angle X-ray scattering (SAXS) and differential scanning calorimetry. Nonafluoro-1-hexene (NFH) and hexafluoropropylene (HFP) were chosen as the third monomers, where they are different in the side-branch length, -(CF₂)₃CF₃ and -CF₃, respectively. In the case of E/TFE/NFH copolymer (ET-C4F9), the crystal phase transition temperature of the original ETFE two-components copolymer was not very much affected by the existence of NFH in the range of NFH content from 0.7 to 3 mol%. Contrarily, the crystal phase transition temperature of E/TFE/HFP copolymer (ET-CF3) was found to decrease drastically with increasing HFP content. The melting temperature and the higher-order structure were also affected sensitively depending on the HFP content. This difference in phase transition behavior between ET-C4F9 and ET-CF3 copolymers is reasonably interpreted as follows: the short side groups (-CF₃) of HFP monomeric unit are included in the crystal lattice of E/TFE chains and the unit cell is expanded gradually with an increment of the HFP content, resulting in the decrease in phase transition point because of easier thermal motion of the chains. On the other hand, the long side groups [-(CF₂)₃CF₃] of NFH monomeric units are excluded out of the crystal lattice and located on the lamellar surfaces or in the amorphous region and do not affect very much the phase transition temperature even when the NFH content is increased. In association with such a change in crystal structure, the long period of stacked lamellar structure was found to decrease remarkably in the case of NFH, whereas it does not change very much for HFP, consistent with the interpretation of the above-mentioned WAXD data.     

面向多商户的第三方电子券系统设计与实现

电子券正成为商家促销的一种新技术手段.在一个已有的定制化电子券系统的基础上,针对服务于多商户的应用背景,对系统的需求进行了重新梳理和流程优化,给出了改造后的系统架构.同时,还对新系统的权限管理与访问控制问题进行了重点分析和设计,引入基于角色的访问控制模型,使之能支持面向多商户的管理.     

试谈铁路运输企业发展第三方物流的对策

从物流及第三方物流的概念着手,主要分析了物流与铁路运输的本质区别,并就铁路运输开展第三方物流优势及存在问题进行了详细分析,重点论述了铁路运输业开展第三方物流的可行性及有关对策。     

不同物流和回收状态下的供应链决策分析

基于第三方物流服务商在供应链管理中的重要性,构造了以第三方物流服务商为主导企业的供应链模型.运用博弈论思想,对制造商回收和零售商回收的两类闭环供应链模型进行求解比较,提出了制造商实施物流外包和废旧品回收的临界条件.最后通过数值算例,分析了动态时域上服务成本和回收成本与制造商决策的关系.     

On the qualitative behaviors of solutions of third order nonlinear differential equations

We present some new results about oscillation and asymptotic behavior of solutions of third order nonlinear differential equations of the form

(r₂(t)(r₁(t)y^′)^′)^′+p(t)y^′+q(t)f(y(g(t)))=0.     

具有可信第三方的认证协议的安全性

讨论了面向通过可信第三方完成对等双方的身份认证并建立一个安全的会话密钥需求的一类认证协议。分析了这类协议的设计目标,将协议的安全性归纳为对协议中所建立会话密钥的四点需求：保密性、真实性、新鲜性和一致性, 并进一步通过实例说明了不满足这些需求的协议可能遭受到的攻击。最后给出对于设计这类协议的一些建议原则,并分析了一个设计较好的协议范例。     

Efficient solution of the 3G network planning problem

The 3G universal mobile telecommunications system (UMTS) planning problem is combinatorially explosive and difficult to solve optimally, though solution methods exist for its three main subproblems (cell, access network, and core network planning). We previously formulated the entire problem as a single integrated mixed-integer linear program (MIP) and showed that only small instances of this global planning problem can be solved to optimality by a commercial MIP solver within a reasonable amount of time ( St-Hilaire, Chamberland, & Pierre, 2006). Heuristic methods are needed for larger instances. This paper provides the first complete formulation for the heuristic sequential method ( St-Hilaire, Chamberland, & Pierre, 2005) that re-partitions the global formulation into the three conventional subproblems and solves them in sequence using a MIP solver. This greatly improves the solution time, but at the expense of solution quality. We also develop a new hybrid heuristic that uses the results of the sequential method to generate constraints that provide tighter bounds for the global planning problem with the goal of reaching the provable optimum solution much more quickly. We empirically evaluate the speed and solution accuracy of four solution methods: (i) the direct MIP solution of the global planning problem, (ii) a local search heuristic applied to the global planning problem, (iii) the sequential method and (iv) the new hybrid method. The results show that the sequential method provides very good results in a fraction of the time needed for the direct MIP solution of the global problem, and that optimum results can be provided by the hybrid heuristic in greatly reduced time.     

Culture,politics and ergonomics

The beginning of a new century is an appropriate moment to consider the role of ergonomics in relation to the problems facing society. To help solve these serious global problems, ergonomics needs to be open to new disciplines, particularly those in the social sciences. Also, it may be difficult to generalize research on human-centred sociotechnical design without taking into account national characteristics, economics and political constraints. Currently there is more interest than ever in what ergonomics has to offer, but to deliver its promise requires a much broader approach than is usual. By adopting such new approaches one may help solve both the problems of the overdeveloped post-industrial societies and those of the societies of the Third World, where a new approach to work and economics may provide an improved chance for development given the recent changes in global economic policy.     

基于.NET平台和B/S结构的第三方客户端物流管理系统的设计

本文采用．NET平台和B／S架构对企业第三方客户端物流管理系统进行设计，对其中的问题提出改进方案，设计思路为：将企业产品放入第三方物流公司的就近库区，使企业把主要精力放在新产品的设计开发上，免除公司配备大量的仓储设施及运输车队所带来的费用和管理问题。