水质预报系统的MPI+OpenMP并行优化研究

OpenMP(Open Multi-Processing)能够在共享存储环境中获得理想的并行性能,MPI＋OpenMP混合并行编程模型更贴近于多核心集群的体系结构。在多核心集群上进行实验,混合模型相对串行程序可缩短95%的运算时间,加速比超过20。实验结果表明,该混合模型比纯MPI并行的系统具有更优的加速比和扩展性,是对纯MPI并行系统的一种改进。     

Many Faces of Security: Discursive Framing in Cross-border Natural Resource Governance in the Mekong River Commission

Abstract

In the past decade, security has emerged as a new discourse in water governance beyond transboundary conflicts and cooperation. This paper will examine how security is framed in the context of international river basin organizations (RBOs), key regional organizations in transboundary water governance operating in many international river basins around the world. As an example of cross-border governance, RBOs can promote joint cooperation and information sharing, and serve as a form to bring together diverse stakeholders. This paper focuses on the discursive construction of ‘security’ in a particular context of cross-border river basin governance in the Mekong River Basin. We ask: How is security framed in the discourse of RBOs? We examine how diverse actors frame security in the context of RBOs and at various scales and around certain management actions in a case study of the Mekong River Commission, a well-established RBO. Attention will be paid to the links between water security, food security, and energy security in the broader water and development discourse. We analyze what the findings mean for cross-border governance more broadly.     

自然资源经济学的难解之题——水资源价格与节约的冲突

日益短缺的水资源面临的价格与节约的冲突,成为自然资源经济学的一个难解之题：水资源严重短缺的趋势,需要通过价格调整其分配与消费,而作为公用事业产品的生活用水,价格的长期粘性不利于水资源节约。提出这个问题,意在提示人们共同探讨破解这一难题的方法。     

The Relative Weights of Direct and Indirect Experiences in the Formation of Environmental Risk Beliefs

Direct experiences, we find, influence environmental risk beliefs more than the indirect experiences derived from outcomes to others. This disparity could have a rational basis. Or it could be based on behavioral proclivities in accord with the well‐established availability heuristic or the vested‐interest heuristic, which we introduce in this article. Using original data from a large, nationally representative sample, this article examines the perception of, and responses to, morbidity risks from tap water. Direct experiences have a stronger and more consistent effect on different measures of risk belief. Direct experiences also boost the precautionary response of drinking bottled water and drinking filtered water, while indirect experiences do not. These results are consistent with the hypothesized neglect of indirect experiences in other risk contexts, such as climate change.     

Water Adherence Factors for Human Skin

On incidental dermal exposure to chemicals in water, a key exposure factor is the amount of water adhering to skin. Although soil adherence factors have been developed for risk assessment, measurements of water adherence on human skin have not been described. In the Environmental Protection Agency's (EPA's) dermal risk assessment guidance, dermal dose from environmental exposures is based upon the flux rate across the skin, which assumes that an unlimited amount of chemical is available for absorption. This assumption is applicable to certain exposure scenarios such as swimming and bathing. However, exposures to contaminated water frequently involve scenarios where the available chemical is limited by the amount of water adhering to the skin, for example, during accidental splashes. We conducted studies in human volunteers to investigate water adherence per unit area of skin after brief contact with water. In two sets of experiments, either water was applied with a micropipette to 10‐cm² areas of the lower leg, foot, and hand, or the foot and hand were briefly immersed in water. In males, using a micropipette, water adherence ranged from 1.93 (foot) to 7.13 μL/cm² (lower leg). In females, it ranged from 1.10 (lower leg) to 4.83 μL/cm² (hand). Hand and foot immersion resulted in relatively higher values of 6.89 and 5.17 μL/cm², respectively, in males, and 5.40 and 6.39 μL/cm² in females. Water adherence was affected by amount of body hair and type of exposure. Water adherence factors can be used to calculate the applied dose per unit area for exposures involving intermittent water contact.     

基于单片机AT89C51的全自动变频恒压供水系统

介绍了一种新型的变频恒压供水系统.该系统根据供水管网的用水情况,调整水泵投入台数及转速,实行全自动恒压供水,达到高效节能的目的;其水泵用变频器软启动,对电网无冲击,能延长水泵的使用寿命.     

“水资源利用与保护”课程新型案例教学模式探讨

社会对环境类人才的能力要求越来越高，教师需要着力培养学生的创新能力，强化训练学生的实践能力。在深入研究案例教学的理论基础上，根据“水资源利用与保护”课程的知识结构、课程特点及教学目标，结合教学对象的学习需求，紧扣世界水环境急剧变化给水资源利用与保护提出的新挑战，面向西部的水资源特性及城市水环境现状，设计教学案例，制定实施案例教学流程，对“水资源利用与保护”课程的新型案例教学模式进行了探讨。     

晚唐五代时期金河黑河水系变迁与环境演变

汉代黑河(删丹河,或名张掖河,又名弱水)与北大河(金河,又名呼蚕水)交汇入注居延海,汉代以后直到唐代之前都没有记载.<元和郡县图志>记载两水分流,金河流注白亭海,张掖河流注居延海.敦煌文献记载晚唐时金河与张掖河交汇流注居延海,使居延海湖面出现一个恢复期.此外,金河和黑河流域地区居民结构变化、农业人口和用水量减少、黑河径流量增加也是居延海湖面增加的原因.     

致用与会通——薛凤祚水利思想蠡测

薛凤祚治学方法的特点,即＂致用＂与＂会通＂。其中,会通包含古今的会通与中西的会通。由《两河清汇》解读薛凤祚的水利思想,比较突出的是其治河和海运的思想。《两河清汇》从体例上言,可谓＂编述之体＂,薛凤祚不仅继承发扬了儒家圣贤的一些学说,也吸收了其前代潘季驯、邱濬等人的观点。观其采择去取,无不以＂致用＂为宗。而其热心译介当时西方的水利器械,可以看作他在中西会通中所作的努力。虽然如此,对于薛凤祚《两河清汇》及其水利思想不可刻意拔高。     

Agent‐Based Modeling to Simulate Contamination Events and Evaluate Threat Management Strategies in Water Distribution Systems

In the event of contamination of a water distribution system, decisions must be made to mitigate the impact of the contamination and to protect public health. Making threat management decisions while a contaminant spreads through the network is a dynamic and interactive process. Response actions taken by the utility managers and water consumption choices made by the consumers will affect the hydraulics, and thus the spread of the contaminant plume, in the network. A modeling framework that allows the simulation of a contamination event under the effects of actions taken by utility managers and consumers will be a useful tool for the analysis of alternative threat mitigation and management strategies. This article presents a multiagent modeling framework that combines agent‐based, mechanistic, and dynamic methods. Agents select actions based on a set of rules that represent an individual's autonomy, goal‐based desires, and reaction to the environment and the actions of other agents. Consumer behaviors including ingestion, mobility, reduction of water demands, and word‐of‐mouth communication are simulated. Management strategies are evaluated, including opening hydrants to flush the contaminant and broadcasts. As actions taken by consumer agents and utility operators affect demands and flows in the system, the mechanistic model is updated. Management strategies are evaluated based on the exposure of the population to the contaminant. The framework is designed to consider the typical issues involved in water distribution threat management and provides valuable analysis of threat containment strategies for water distribution system contamination events.