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。     

‘I’m worried about the correctness’: undergraduate students as producers of screencasts of mathematical explanations for their peers – lecturer and student perceptions

Undergraduate mathematics is traditionally designed and taught by content experts with little contribution from students. Indeed, there are signs that there is resistance from mathematics lecturers to involve students in the creation of material to support their peers – notwithstanding the fact that students have been successfully engaged as co-creators of material in other disciplines. There appears to be little research into what issues may lead to reservations to using student-created content in mathematics learning. This paper takes a case study approach to investigate the reasons for lecturers’ resistance to undergraduate student contributions to learning material, in particular with a view to the production of screencasts of mathematical explanations. It also investigates the views of students producing mathematical screencasts. This study is part of a larger research project investigating undergraduate involvement in mathematics module design. Four second-year students, who were producing mathematics screencasts as part of an internship, and five academics, were interviewed to gain an understanding of their views of the value of student screencasts. The interviews focused on the particular contributions students make to screencasts, outcomes for the students and level of lecturer acceptance of these resources. We argue that students benefit from creating screencasts for their peers by gaining deeper mathematical understanding, improved technological skills and developing other generic skills required of today's graduates. In contrast, we confirm lecturer resistance to using student-generated screencasts in their teaching materials. Lecturer reservations pertain to students’ lack of mathematical maturity and concerns over the mathematical integrity of the content that students produce. We conclude that close collaboration between students and lecturers during the design and production phases of screencasts may help lecturers overcome reservations, whilst preserving the benefits for students. In addition, we provide evidence that the process is a valuable professional development opportunity for the lecturers themselves.     

集对分析多元模糊评价法在水资源可再生能力评价中应用

水资源可再生能力受多种因素影响,因素间关系错综复杂,水资源可再生能力综合评价是一项复杂的系统工程.以集对分析理论为基础,用新定元准则、主同、超同和同化度等新概念发展集对分析,建立了一种新的流域水资源可再生能力评价模型—集对分析多元模糊评价模型(MFSPAFM).应用该模型对黄河流域及其上、中、下游典型省份的水资源可再生能力进行了综合评价,并与常规集对分析模型和可变模糊等模型评价结果进行了比较.实例应用显示该模型能够真实地反映水资源可再生能力状况,评价结果更符合客观实际.研究表明,集对分析多元模糊评价模型结构简单,计算简洁,可行有效,适用于水资源可再生能力综合评价.     

基于GA-SVM的水资源可持续利用评价

把水资源可持续利用评价问题看成是一个分类问题,利用支持向量机良好的鲁棒性和分类精确性进行评价,并用遗传算法优化了SVM的参数,使其分类精确度更高.对黑龙江省十三个地区进行了实例应用,与人工神经网络和GD-IIM法的结果进行了比较,结果表明,支持向量机模型简单、通用、精度高,可在水资源可持续利用实际评价中推广应用.     

Inexact joint-probabilistic chance-constrained programming with left-hand-side randomness: An application to solid waste management

In practical waste management systems, amounts of waste transported and treated are not always equal on a daily basis. To distinguish between these two kinds of amounts and reflect their random relationships effectively, an inexact joint-probabilistic left-hand-side chance-constrained programming (IJLCP) method was developed and applied to a municipal solid waste management problem under dual uncertainties. Dual uncertainties are defined as two kinds of uncertainties existing in the same programming model. Improving upon conventional right-hand-side chance-constrained programming, the IJLCP can not only reflect uncertainties presented in terms of interval parameters (unit transportation/treatment costs, capacities of waste treatment facilities, waste generation rates, waste transportation/treatment amounts and so on) and left-hand-side random variables (the relationship between waste transportation and treatment amounts), but also examine the reliability of satisfying (or risk of violating) the entire system constraints. A non-equivalent but sufficient linearization form of IJLCP for solving this type of problem was proposed and proved in a straightforward manner. The performance of IJLCP was analyzed under scenarios at joint and individual probabilities and compared with the corresponding internal-parameter programming model. The results indicated that the net system costs would both decrease with increasing joint probability levels and decrease slightly at different individual probabilities with the same joint probabilities. The two types of dual uncertainties were discussed as well.     

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.     

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.     

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.     

Criticality of metal resources for functional materials used in electronics and microelectronics

In microelectronic devices a multitude of essential, indispensable metals is functionalized. Many of these metals are scarce and rather often only mined as by‐products of base metals. For the industry but also for the development of new technologies this situation can evoke serious restrictions. In order to foresee, validate and minimize such risks a criticality concept is described. In this concept quantitative and qualitative criteria like scarcity, geo‐political restrictions, economic availability, efficiency, recyclability, potential dissipation, social and cultural factors, ecologic impacts, etc. are considered in order to define a reliable, sustainable and responsible implementation of strategic functional metals and materials into technical systems. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)