Morphological behavior of model poly(ethylene‐alt‐propylene)‐b‐polylactide diblock copolymers

A set of well‐defined poly(ethylene‐alt‐propylene)‐b‐polylactide (PEP‐PLA) diblock copolymers containing volume fractions of PLA (f_PLA) ranging between 0.08 and 0.91 were synthesized by a combination of living anionic polymerization, catalytic hydrogenation, and controlled coordination‐insertion ring‐opening polymerization. The morphological behavior of these relatively low‐molecular‐weight PEP‐PLA diblock copolymers was investigated with a combination of rheology, small‐angle X‐ray scattering, and differential scanning calorimetry. The ordered microstructures observed were lamellae (L), hexagonally packed cylinders (C), spheres (S), and gyroid (G), a bicontinous cubic morphology having Ia3 d space group symmetry. The G morphology existed in only a small region between the L‐C morphologies in close proximity to the order–disorder transition (ODT). Transformations from L to G were observed upon heating in several samples. The efficacy of the reverse G to L transition in one sample was cooling rate dependent. The PEP‐PLA Flory–Huggins interaction parameter as a function of temperature χ_PEP‐PLA(T) was estimated from T_ODT's by mean‐field theory and subsequently used in the construction of the experimental PEP‐PLA morphology diagram (χN versus f_PLA). The resultant morphology diagram was symmetric there were the well‐defined L‐C morphology boundaries. The low molecular weight of the materials imparted no significant deviation from previously documented diblock systems. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 2364–2376, 2002     

Stochastic differential game model of a common property fishery

The paper presents a stochastic differential game model of a common-property commercial fishery and determines a feedback Nash equilibrium of the game. Closed-form expressions for the value functions, the equilibrium harvesting strategies, and stationary distributions of the fish stock are derived. Sensitivity analyses with respect tot he model parameters are carried out. The paper also considers equilibrium outcomes under joint maximization and surplus maximization. In the latter case, an optimal market size (i.e., number of firms) is identified.The research of the first author was supported in part by Grant 5.20.31.02 from the Danish Research Council for the Social Sciences. The research of the second author was supported in part by the CRGC Fund of the University of Hong Kong. The authors would like to thank the editor for constructive comments.     

PCB废水处理回用率应有个逐步提高的过程

文章概述了PCB工业废水和环境污染方面的情况。中国PCB工业要得到发展与进步,必须坚决走废水处理—循环应用的道路。我国PCB废水处理回用比率需要有个逐步提高的过程。     

A fuzzy inexact two-phase programming approach to solving optimal allocation problems in water resources management

Inappropriate agricultural activities are the main reasons of water shortage and environmental pollution in many rural areas. How to generate preferred decision schemes for agricultural activities is a critical issue for decision makers. In this study, a two-phase programming approach is advanced for regional water resources allocation in a rural region of China. The approach shows applicability when the uncertain inputs are provided as intervals and such uncertainty is desired to be delivered to the corresponding solutions. Multiple control variables are introduced both in the objective function and constraints of the programming model, which make it possible for the constraints being relaxed under respective levels. A more satisfactory objective value can thus be expected as well as the impact of each constraint on the modeling outputs can be clarified effectively. The decision variables are useful for decision makers to justify and/or adjust the decision schemes for agricultural activities through incorporation of their implicit knowledge on water allocation management.     

求解多目标资源分配问题的改进蚁群优化算法

多目标资源分配问题就是将有限资源分配到不同事件来获得预期目标.建立了多目标资源分配问题的数学模型,提出了一种有效求解该问题的改进蚁群优化算法：设计了一种多目标资源分配问题的可行方案构建机制,定义了蚁群优化算法中的信息素形式及其更新方式,提出了一种新的概率选择形式;通过以上改进有效地提高了蚁群优化方法的效率.为了验证此方法的有效性,将蚁群优化方法与混合遗传算法的实验结果进行了对比分析,证明此方法优于混合遗传算法.     

基于高端SAN存储系统虚拟整合技术研究

随着计算机存储技术的飞速发展,高端SAN存储系统越来越多应用于高性能运算领域.通过存储网络整合、zoning整合、逻辑卷映射整合、外挂存储整合等技术,基于高端SAN存储系统,整合中低端系统,使其共享I/O通道带宽和缓存资源,实现多套SAN存储资源共享,提高存储系统整体性能.对保护设备投资,最大限度地发挥存储效率有着重要作用.     

一个人力资源管理系统的实现

随着计算机应用领域的飞速发展,人们开始利用计算机解决一些实际问题.本文的人力资源管理系统,以C/S模式实现了人力资源管理的各项功能,包括档案管理、出勤管理、工资管理、用人申请、业绩考核、人员调动等功能.系统运行后,满足了人力资源管理的需要,提升了管理效率.     

熵权法在水资源可持续利用评价中的应用

介绍了熵权基本理论,将熵权评价法应用于山西省11个市水资源可持续利用中,并对山西省11个市的水资源可持续利用情况进行了排序.实例研究表明,熵权法在确定评价指标方面克服了人为主观性对评价过程的干扰,提高了评价的科学性.     

基于极大熵投影寻踪组合法的水资源预警评价模型

利用基于极大熵准则赋权和基于实数加速遗传算法的投影寻踪方法相结合的组合附权法确定了各预警指标的权重;采用层次分析法计算水资源可持续利用复合系统中各子系统所占权重;利用综合评价模型计算出哈尔滨市水资源可持续发展指数;最终得到哈尔滨市水资源可持续利用预警结果.     

资源富集区煤炭资源开发与电力生产——基于国家能化基地榆林市的实证分析

基于热点经济区国家能化基地榆林市1990-2012年的实际数据,采用协整分析、误差修正模型和Granger因果关系检验,对资源富集区煤炭资源开发与电力生产关系进行了统计实证研究.结果显示:榆林市煤炭资源开发与电力生产之间存在长期稳定的均衡关系,且二者间存在由前者到后者的单向格兰杰因果关系;榆林市煤炭资源的开发、利用极大地促进了当地的电力生产与供应,但煤向电能转化的效率偏低.建议煤、电联合、建设大型煤电基地、提高煤电转化效率和促进电力生产多元化是榆林煤电产业的发展方向.