遗传算法在水资源与水环境研究中的应用综述

论述了遗传算法在水污染控制规划、水资源优化配置、水库(群)优化调度、地下水系统的模拟与优化、水环境模型参数估计等水资源领域中的应用,并对遗传算法在该领域的应用进行了展望。     

水沙条件改变后河流水环境及其改善措施探讨

河流水资源的开发利用改变了河流原有的水沙条件,甚至破坏了水环境与河流系统之间的平衡关系;认识新水沙条件下河流水环境的变化特点,探索有效的水环境改善措施,对实现河流可持续开发、维护河流健康有重要意义。以水沙与污染物间的作用规律为基础,结合水库修建前后河流的水沙和河床边界条件变化,讨论了水沙条件变化后河流水环境的特点,并就改善河流水环境的水库调度措施进行初步探讨。     

干旱区内陆盆地水资源的合理配置——以甘肃省高台县为例

通过对高台县水资源现状分析,指出了在水资源开发利用过程中存在的问题,提出三种水资源利用配置方案:①开发地表水为主的水资源配置方案;②开发地下水为主的水资源配置方案;③地表水、地下水兼顾的水资源配置方案。进行对比分析后得出,地表水、地下水兼顾的水资源配置方案既兼顾了高台县工农业生产的可持续发展,又保证了黑河正义峡下泄流量,因而是目前较为合理的水资源配置方案。     

Design and demonstration of policy-based management in a multi-hop ad hoc network

In this paper, we propose a policy-based framework for the management of wireless ad hoc networks and briefly describe a characteristics-based taxonomy that provides a platform to analyze and compare different architectural choices. We develop a solution suite that helps achieve our goal of a self-organizing, robust and efficient management system. One of the main contributions of this work is the prototype implementation and testing of the mechanisms and protocols comprising our framework in a multi-hop ad hoc network environment. Experiments are conducted using both an emulated ad hoc network testbed and a true wireless testbed. Degradation in management system performance is observed as the number of hops between a policy server and client increases. Our proposed k-hop clustering algorithm alleviates this problem by limiting the number of hops between a server and client. We demonstrate the operation of our prototype implementation, illustrating QoS management in a multi-domain ad hoc network environment using the proposed cluster management, redirection, and policy negotiation mechanisms.     

ERP中集成订单实现系统的开发

在知识经济时代，实施ERP是中国企业的发展趋势。集成订单实现系统是实施ERP的基础部分。本文针对北台烧结厂的实际情况，设计开发了集成订单实现系统的流程，为烧结厂的电子化管理探索出了一条新路。     

一种支持多用户SLA的EPON上行带宽分配算法设计

在接入网服务等级协定的基础上,分析了以IPACT和CyclicDBA为代表的EPON上行动态带宽分配算法,讨论了其对EPON上多用户SLA支持所存在的固有缺陷。提出了适合SLA应用的EPON控制帧结构:授权帧和请求帧。根据这两种控制帧,设计了一种新型的支持多用户SLA的EPON上行信道带宽分配算法,等级轮询固定周期算法。通过理论分析和计算机仿真测试表明该算法针对EPON不同类型的接入用户均达到了较理想的性能指标,高优先级业务良好的时延和时延抖动特性,各种业务队列的尺度平稳,同时HPFCT还解决了传统轮询算法中低负载时下行带宽浪费明显的问题。     

Ichthyoplankton abundance and variance in a large river system concerns for long-term monitoring

System-wide spatial patterns of ichthyoplankton abundance and variability were assessed in the upper Mississippi and lower Illinois rivers to address the experimental design and statistical confidence in density estimates. Ichthyoplankton was sampled from June to August 1989 in primary milieus (vegetated and non-vegated backwaters and impounded areas, main channels and main channel borders) in three navigation pools (8, 13 and 26) of the upper Mississippi River and in a downstream reach of the Illinois River. Ichthyoplankton densities varied among stations of similar aquatic landscapes (milieus) more than among subsamples within a station. An analysis of sampling effort indicated that the collection of single samples at many stations in a given milieu type is statistically and economically preferable to the collection of multiple subsamples at fewer stations. Cluster analyses also revealed that stations only generally grouped by their preassigned milieu types. Pilot studies such as this can define station groupings and sources of variation beyond an a priori habitat classification. Thus the minimum intensity of sampling required to achieve a desired statistical confidence can be identified before implementing monitoring efforts.     

Time constraints set by prime contractors for their sub-contractors

The concept of pacing is described in an articulate manner which will enable readers to discuss the views put forwards. The nine major activities are divided into two types and are discussed in detail together with the methods used by the prime contractors to allocate time windows and the underlying logic employed.     

Real-time applications in a CRMA network: a performance analysis

This paper analyses bandwidth allocation schemes for managing real-time applications (Variable Bit Rate video and voice) in a CRMA network. A methodology to compute the Quality of Service (QoS) experienced by variable bit rate (VBR) video and voice sources is proposed. As VBR video applications only tolerate extremely low packet loss rates (< 10⁻⁸), we need a computational approach to estimate very low tail probabilities. Studying the QoS with a simulation technique is not feasible, because computational costs make it almost impossible to estimate tail distribution probabilities lower than 10⁻²−10⁻³. Therefore, to achieve this target, we propose a model which represents a CRMA network's worst case behaviour (i.e. a scenario with maximum network congestion), and which can be solved analytically. By solving this model for different bandwidth allocation schemes, we can obtain the corresponding bounds on the QoS experienced by VBR video users. Finally, for those bandwidth allocation schemes which provide an acceptable QoS for VBR video traffic, we also estimate (via a trace-driven simulation) the QoS achieved by voice users.     

分布并行系统的并行程序设计环境

分布式并行计算机系统中，由于没有共享内存以支持处理机间的数据交换，因而需采用ｍｅｓｓａｇｅｐａｓｓｉｎｇ的方式实现并行计算中处理机间的数据通讯，并行程序设计环境作为程序员使用并行计算机系统工具，对于并行处理技术以及并行计算机系统的发展与推广应用都有重要的作用，本文将分布基于ｍｅｓｓａｇｅｐａｓｓｉｎｇ的并行计算机系统中的并行程序设计环境的基本问题，并介绍几种典型的并行程序设计环境。