都江堰灌区水情数据库存在的问题及解决方案

为了适应都江堰灌区信息化的发展,根据都江堰灌区自身的特点和国家有关标准,对都江堰灌区现有水情数据库表结构以及字段标识符进行了标准化建设。在此过程中遇到了一些问题,文章对这些问题进行了分析,并提出了相应的解决方案,使灌区水情数据库的信息和数据得到更好的维护、存储、共享。     

Experimental investigations of polypropylene and poly(vinyl chloride) composites filled with plerospheres

Plerospheres, defined here as superfine spherical particles (0.5–5 μm) separated from fly ash (rather than as other solid spherical particles, as some have used the term), are separated from coal fly ash but are dramatically different from it. Plerospheres can be used as polymer fillers to improve the properties of composites. With plerospheres used as fillers for polypropylene (PP) and unplasticized poly(vinyl chloride) (UPVC), the effects of the filler content, the particle sizes of the plerospheres, and the coupling agent on the composite properties were studied. The particle sizes of the plerospheres were 2 and 5 μm. The results suggested that the notched impact properties both at a normal temperature and a low temperature and the tensile and flexural properties of plerosphere/PP increased significantly when the content was increased from 0 to 30 wt % and further increased with the addition of a coupling agent. Differential scanning calorimetry indicated that the thermal properties of the plerosphere/PP composite improved. The surface characteristics and morphology of the impact fracture surface were examined in detail with scanning electron microscopy. The rheological performance of plerosphere/UPVC pipe composites obviously improved; the plasticizing time was shortened, and the maximum torque was reduced. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 126–131, 2004     

宁夏河套灌区节水目标与发展潜力

河套灌区发展节水灌溉要因地制宜,总体目标的实现应该分阶段进行。用灰色理论进行河套灌区的水资源供需分析,预测2010年节水潜力为10.30亿m3,2020年为13.81亿m3。灌区节水潜力有:采取工程措施、调整作物种植结构、开采浅层地下水、改进地面灌溉方式、发展灌水技术、提高灌区节水灌溉管理水平等。     

冠醚/PVC+TPB固态膜对溶液中Li+输送特性的研究

研制了苯并１２－冠－４（Ｂ１２－Ｃ－４）＋聚氯乙烯（ＰＶＣ）＋磷酸三丁酯（ＴＢＰ）固态膜实验考查了各种因素对Ｌｉ＋膜输送特性的影响结果表明，增加膜上冠醚含量，提高内相溶液Ｌｉ＋浓度和渗析温度，降低离子溶剂化作用等可加快离子输送速率，但选择性将受到影响论文对离子膜输送机理进行了讨论Ｌｉ＋与冠醚化合物形成配合物后经膜相扩散输送，阴离子以离子对形式相随输送及Ｈ＋的反相渗析以保持体系的电中性     

不同坡度下压力对滴灌毛管均匀度的影响试验

以内镶式滴灌带和薄壁滴灌带为研究对象,测定了平坡、±0.5%坡度和±1%坡度时,不同入口压力下滴头沿毛管的流量分布和水力损失,并结合滴头的制造偏差,计算得出不同坡度和压力条件下滴灌毛管的均匀度。试验结果表明,将毛管铺设成恰当的顺流下坡坡度或提高入口压力均可提高毛管的滴灌均匀度。     

A Neural Networks Approach for Deriving Irrigation Reservoir Operating Rules

A neural networks approach is applied to the derivation of the operating rules of an irrigation supply reservoir. Operating rules are determined as a two step process: first, a dynamic programming technique, which determines the optimal releases byminimizing the sum of squared deficits, assumed as objective function, subject to various constraints is applied. Then, theresulting releases from the reservoir are expressed as a functionof significant variables by neural networks. Neural networks aretrained on a long period, including severe drought events, andthe operation rules so determined are validated on a differentshorter period. The behaviour of different operating rules is assessed by simulating reservoir operation and by computing several performance indices of the reservoir and crop yield through a soil water balance model. Results show that operating rules based on an optimization with constraints resembling real system operation criteria lead to a good performance both in normal and in drought periods, reducing maximum deficits and water spills.     

Ecological perspectives on regulation and water allocation for the Ord River,Western Australia

Water management agencies throughout Australia are attempting to find a balance between the water requirements of ecological and socio‐economic environments as part of a holistic approach to managing flow‐dependent river ecosystems. Environmental water provisions are under consideration for the Ord River in far northern Western Australia. This river has been regulated for irrigation and there are plans for substantial expansion. Like other semi‐arid and tropical rivers, however, the hydrology of the Ord River is highly variable and unpredictable, and therefore, proportionate water release strategies for the environment that are based on average monthly flows are unsuitable. Regulation continues to produce pronounced ecological changes throughout the river system as the impacts of flow regime are negated. There is a dichotomy in optimal flow regimes for the contrasting management aspirations of ecological restoration based on low seasonal flows, and the dilution flows required for the drainage of agricultural effluent. Whilst current agricultural land and water management practices continue, the two cannot coincide, and consequently, a decision should be made regarding which environmental water allocation holds the primary value. Such a decision would guide the appropriate dry season flow regime on the lower Ord River. Copyright © 2002 John Wiley & Sons, Ltd.     

Synthesis of Thick Tl-Based High-Tc Oxide Layer Through a Diffusion Process

Tl-based high-T _c oxide layers have been synthesized through the reaction between Tl-free substrate and coating layer containing Tl. The coating layer with the eutectic composition in V₂O₅-Tl₂O₃ system much enhances the formation of Tl-2223 phase without degrading its superconducting properties. The TIF substitution for T1₂O₃ in the coating layer promotes the formation of Tl-1223 phase, which significantly improves the I _c-B performance at higher temperatures. The behavior of F during the reaction has been studied. Thick Tl-1223 layer is formed on Ni tape with good bonding through the diffusion reaction.     

农村电力排灌站电动机在低电压下运行的情况分析及解决办法

根据三相异步电动机的工作原理和基本公式，对三相异步电动机带动水泵在低电压下运行的情况进行分析，并相应地提出一些解决办法．     

适于渠系的波涌流自动灌溉设备的研究与应用

波涌流灌溉是一种新型的地面节水灌溉技术,根据目前的灌区现状,研制开发出一种适于在渠系输水条件下,能够节水、节能、投资省、造价低、性能稳定、群众易于接受的以渠道内灌溉水本身为动力的波涌流自动灌溉设备,并且可利用浑水进行灌溉,不需要净水处理,具有灌水均匀、推进速度快、无污染等优点,是一种很适合我国国情的灌水设备。