我国跨行政区流域生态补偿机制研究 ——以淮河流域、太湖流域为例

流域生态补偿是利用经济手段对流域生态的外部性进行矫正的一种手段。政府强干预型与市场主导型的流域生态补偿机制都各有优缺点。当前,我国流域生态补偿存在法律机制尚不完善,水资源的产权模糊,补偿主体不明确,补偿方式单一,公民参与渠道不畅等困境。为构建高效的跨行政区流域生态补偿机制,必须制定专门性的流域生态补偿法律,充分发挥地方立法的自主性,健全流域生态补偿的法律体系;既要在近期充分发挥政府在流域生态补偿中的主导作用,又要在远期着眼于建立市场手段为主的流域生态补偿机制;拓宽公众参与途径,建立信息公开机制以及公众参与的经济激励机制,以提升流域生态补偿的制度认可度与制度效用。     

输送黏性介质时叶轮出口角对泵性能的影响

为了研究离心泵在输送黏性介质时,叶轮出口角对泵性能的影响,采用FLUENT软件,对2种不同叶轮出口角的 离心泵,分别在清水和5种不同黏性的油性介质下,进行数值模拟分析,预测离心泵在各工况下的水力性能。结果表明： 输送介质为清水时,增大出口角能提高扬程但会降低水力效率;介质运动黏度介于10. 80~ 65. 00 mm2／s时,增加叶轮出 口角能同时提高扬程和效率;介质运动黏度≥65. 00 1111112/S时,增加出口角不能改善其水力性能。文章研究结果能改善 离心泵的水力设计方法,确保泵的高效运行。     

双螺杆泵Ω形对称型螺杆流场数值分析

由于螺杆泵几何结构及流体流动状态较为复杂,其压力分布和速度等特性很难用数学解析法来分析计算。本文利用参数化设计模块建立双螺杆泵Q形对称型螺杆三维模型,构建双螺杆流道的流场分析模型,运用有限元分析方法得出了双螺杆泵流道内压力场和速度场分布规律。结果表明：流体在流道中的流速分布具有规律性,整个流道的流场速度高低交替变化,在螺杆与衬套间隙处的流动为层流,螺旋面接触区内的流动为复杂的湍流,离螺杆啮合区近的螺旋槽内易发生涡流。本研究结果对于了解双螺杆泵螺杆工况下的性能情况具有重要的参考价值。     

公平合理利用原则在国际水法中的适用局限及其反思

作为国际水法的基本原则,公平合理利用原则具有条约法及习惯法的规范基础,并且可指导跨界水道的利用及水资源分配,但是其抽象性及模糊性降低了适用的确定性。公平合理利用原则适用的局限性主要表现为理论基础不成熟,概念难以统一明确,非排他性考虑因素多元但无优先次序等方面。对公平合理利用原则的反思要求充分尊重跨界水道的自然特性,遵从不造成重大损害原则及国际合作原则,厘清相关考虑因素的优先次序,推动建立水道国家的利益共识,从而实现流域国家对跨界水道的公平合理利用。      

太湖流域的治水传统与水生态文明的承传

通过对太湖地区传统水利生态的一些基本规律的认识,诸如太湖与三江一体化,活水周流等,分析了水生态文明结构的长期稳定性,及其水文生态结构的长期承传性。新时代下基本生态水文结构所形成的水环境问题,仍可以从古代的水利生态结构中寻求解决之路。许多现代水利工程所产生的问题,仍可以从古代的经验中得到解决。水污染的解决,景观水面的增加,古代的活水周流经验可以直接应用。传统文人所重视的水文景观,需要在现代社会承传并推广。     

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.