粮食生产水足迹动态演变及分解效应

基于水足迹方法构建粮食生产水资源匹配指数,从用水总量、来源结构和粮水匹配关系三个方面分析粮食生产用水的动态演变特征,并采用LMDI模型将粮食生产用水变动分解为9类效应,研究结果表明:粮食生产水足迹变动经历小幅下降——快速回升——企稳上升三个阶段,粮水匹配度较差且矛盾趋于激化。从分解效应看,三产结构调整和节水技术进步是减少粮食生产用水的主要因素,但种植结构调整以及用水效率改善未发挥预期节水效果,粮水匹配关系恶化、水土资源贫乏及二者匹配度较差均不利于缓解农业用水压力。     

拙政园小沧浪水院空间分析

拙政园是中国传统私家园林的代表作品之一。小沧浪水院位于拙政园西部,院落虽小,但曲折有致,空间变化丰富。小沧浪水院在整个园林的景域组织中属于幽深屈曲,深邃回合的景物空间,是利用建筑和水体创造奥如景域的典型,在水院空间的处理中很有特色。本文分析了小沧浪水院视觉莫穷、往复无尽的空间特征,从空间深度、空间形态、建筑形式、流线组织等方面分析了小沧浪水院空间处理的特点和方法。     

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.     

李家坝煤矿斜井开拓局部冻结关键技术研究

斜井冻结技术尚处于摸索研究阶段，国内无统一的施工规范。在李家坝煤矿斜井冻结工程实践的基础上开展应用性研究，详细阐述了斜井局部冻结的设计原则、施工关键技术，尤其是快速造孔施工及冻结管保温层施工工艺，提出了冻结管保温接头处理方式，成功应用了斜井冻结步进式投入法，解决了斜井局部冻结关键技术，为类似局部冻结工程提供了借鉴和参考。