NETWORK MODEL FOR DECISIONSUPPORT IN MUNICIPAL RAW WATER SUPPLY1

ABSTRACT: A water supply network optimization model called MODSIM3 is presented as a decision-support tool for aiding city staff in determining how best to utilize and exchange existing and potential water supplies with other users in a river basin. The model is applied to the City of Fort Collins, Colorado, water supply system as a means of determining optimum ways the City can utilize direct flow rights, storage rights, and exchangeable waters from various sources. Results clearly confirm both the benefits of the use of exchanges and the value of MODSIM3 as a water supply planning and management tool.     

THE IMPACTS OF WATERWAY USER FEES ON GRAIN TRANSPORTATION ON THE SNAKE-COLUMBIA RIVER1

ABSTRACT: Grain transportation is a major economic activity on the multiple use Snake-Columbia River System. Congress is currently considering increased transportation user fees aimed at recapturing federal expenditures for waterway operations and maintenance. Three types of fee structure and four levels of cost recovery are evaluated using a network program model. In each case traffic is diverted away from the river to other Puget Sound ports via truck and rail transport modes. Grain shippers in the region will be adversely affected by a higher transport bill. The Lower Columbia River port economic activities will be negatively affected; however, competitive uses of the river, recreation, and hydroelectric generation will likely benefit modestly.     

On the horizontal homogeneity of mass-related aerosol properties

We studied the mass-related aerosol properties, simultaneously attwo sites at the urban roof top level in the same city. Nosystematic influence of the wind vector on the difference in theaerosol concentrations between the two locations could be found.These results are compared with results from a second, similarexperiment over a larger distance including one urban and onerural site. Surprisingly, we could not detect a tendency whichwould indicate that sampling air at distance in the order of 1 kmwould be less affected by the heterogeneity than samplingdistanced in the order of 10 km apart. On the contrary, theresults suggest that mass-related properties at two sites in thesame city are not necessarily more similar than at an urban and arural site outside the city. These results stress the limitedhorizontal homogeneity of urban atmospheric aerosol. As aconclusion it is suggested that single-site measurements of mass-related aerosol properties should be considered to berepresentative for an area smaller than 1 km² on size.     

基于自回归GA-BP神经网络的AQI预测

基于徐州市2013年12月—2018年11月的空气质量指数日均值,建立了时间序列自回归输入的GA-BP神经网络模型用于空气质量指数预测。结果表明,所建立的网络模型能够准确预测徐州市空气质量指数的变化趋势,其中夏季预测相对误差18. 23%,仿真均方根误差(RMSE)为14. 59;冬季预测相对误差9. 14%,仿真RMSE为11. 47。     

A Screening Procedure for Identifying Acid-Sensitive Lakes from Catchment Characteristics

Monitoring of Wilderness lakes for potential acidification requires information on lake sensitivity to acidification. Catchment properties can be used to estimate the acid neutralizing capacity (ANC) of lakes. Conceptual and general linear models were developed to predict the ANC of lakes in high-elevation (2170 m) Wilderness Areas in Californias Sierra Nevada mountains. Catchment-to-lake area ratio, lake perimeter-to-area ratio, bedrock lithology, vegetation cover, and lake headwater location are significant variables explaining ANC. The general linear models were validated against independently collected water chemistry data and were used as part of a first stage screen to identify Wilderness lakes with low ANC. Expanded monitoring of atmospheric deposition is essential for improving the predictability of lake ANC.     

论组建三级环境监测网的必要性和重要性

论述了组建三级环境监测网的必要性和重要性及在环境监测中的作用,组建三级环境监测网是环境监测工作不断拓展和深化发展的需要。     

延安市近年来大气环境质量的变化分析

介绍了延安市市区大气环境中主要污染物二氧化硫、氮氧化物、总悬浮颗粒物近年来的变化特征,并对其进行了原因分析,从而找出了影响市区大气环境质量的一些主要因素。在此基础上进行了探讨,提出了进一步改善延安市大气环境质量的建议与对策。     

交通事故发生规律与城市道路系统的规划设计研究

笔者分析了城市交通事故发生率与道路等级、道路断面形式、路网密度、交叉口形式、道路车速的关系及交通事故人群的分布规律,认为道路宽而稀、支路缺乏、街道功能不清是我国城市道路网与用地微观布局的基本特点。大量数据分析表明,这种路网体系与我国的城市交通事故率偏高有着密切关系。路网规划是城市路网建设的基本依据,笔者认为,应当将降低城市交通事故率作为路网规划的考虑内容之一,同时指出,应在路网规划中合理选择道路断面形式、交叉口形式,建议适度加密路网、健全支路体系、理清街道功能,并考虑城市道路的车速控制与驾驶心态调整。     

城市基础设施安全系统的结构与和谐发展

城市基础设施安全关系到人民生命财产的安全,也制约着城市经济、社会、环境的协调发展。整个安全系统由7个安全子系统组成,它们相对独立,协调运转,共同影响城市经济、社会和环境的效益。笔者运用ANP法(网络分析法)剖析了城市基础设施安全系统的结构及其内在规律;应用科学发展观,整合城市基础设施安全系统和经济系统、社会系统、环境系统之间相辅相成的发展关系,提出一体化的可持续发展模式;同时指出,可持续发展的动力、资源和条件都受到城市内外经济、社会、环境因素的制约,为满足整个安全系统和谐发展的要求,必须科学规划和管理城市基础设施,保证其安全运行。     

移动Ad hoc网络路由协议的安全性分析与对策

移动Ad hoc网络是一种自组织、多跳的无线网络,由于其独特性能使移动Adhoc网络面临着比现有网络具有更大的安全挑战,其中路由安全对该网络的安全性起着关键性的作用。在介绍移动Ad hoc网络主要路由协议及其特点的基础上,笔者深入研究了移动Ad hoc网络路由协议中存在的黑洞、拒绝服务等安全漏洞;详细分析了几种主要的Ad hoc路由协议的安全性增强方案;根据不同路由协议的特点,分别提出了利用单向散列链改进距离矢量路由协议安全性的两种方案;分析了一种用于改善源路由协议安全性的方案的可行性。最后,指出了移动Ad hoc网络路由协议安全性问题的进一步改进和研究方向。