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当前,按照可持续发展的要求,完善科学的水资源管理体制,明确规范水资源使用程序,运用计划经济的合理模式和市场经济的有效手段,开发好、管好、用好水资源已成为历史的必然. 相似文献
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Zhou Bo Liao Renkuan Li Yunkai Gu Tao Yang Peiling Feng Ji Xing Weimin Zou Zhichao 《应用聚合物科学杂志》2012,126(2):423-435
Adding inorganic materials in SAPs to synthesize organic–inorganic composite superabsorbent polymers (OICSAPs) can effectively improve salt‐tolerance, gel strength, thermal stability, and water retention. However, most researches mainly focus on synthesizing process optimization and new multifunctional products, lacking reports on how ions affected water‐absorption characteristics and mechanism of OICSAPs and its influence on summer maize root growth. On the basis of these, we set up laboratory experiments and field cultivation experiment, using environmental scanning electron microscopy (ESEM) and fractal theory to study the questions above. Results show that OICSAPs have better salt‐tolerance, while cations and concentration affected its water‐absorption characteristics significantly. With higher cation valence, larger ionic radius, and concentration, its water‐absorption rate reduced remarkably as Na+ < K+ < Mg2+ < Ca2+ < Fe2+ < Fe3+ < Al3+ < Cu2+, while the effects of anions could be neglected. The OICSAPs presented typical honeycomb membrane‐like 3D crosslinked network structure, but Ca2+, Mg2+, Fe2+, Fe3+, Al3+, and Cu2+ would damage the structure (Cu2+ with the most significant effect) in local microdomain, and changed the complexity of pores. In the experiment, higher concentration could reduce water‐absorption rate without changing micromorphological characteristics. Applying OICSAPs will reduce total length, surface area, and volume of summer maize root, while promoting absorbing and transmitting ability by larger root diameter and the proportion of root <0.5 cm. All these results will provide a theoretical basis on application, marketing, and product development of OICSAPs. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012 相似文献
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The 0-1 knapsack problem is a classic combinational optimization problem. However, many exiting algorithms have low precision and easily fall into local optimal solutions to solve the 0-1 knapsack problem. In order to overcome these problems, this paper proposes a binary version of the monkey algorithm where the greedy algorithm is used to strengthen the local search ability, the somersault process is modified to avoid falling into local optimal solutions, and the cooperation process is adopted to speed up the convergence rate of the algorithm. To validate the efficiency of the proposed algorithm, experiments are carried out with various data instances of 0-1 knapsack problems and the results are compared with those of five metaheuristic algorithms. 相似文献
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The catch can method is traditionally used for evaluating performance of drip systems. Two variations of this method are commonly applied in laboratory testing of drippers: the sequential and the simultaneous method. This study compared uniformity and measurement uncertainty of the two methods, with the overall aim of improving irrigation water management. The simultaneous method was found to have a lower coefficient of variation (Cv) and measurement uncertainty, indicating that it is more accurate than the sequential method. In all the tests, however, the Cv was determined to be <5%, which is acceptable as per the current reference standard. 相似文献
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多机系统调速侧电力系统稳定器GPSS的设计 总被引:1,自引:1,他引:0
低频振荡是一种不利于电力系统安全和稳定运行的现象,而电力系统稳定器(PSS)可以有效抑制低频振荡。由于励磁系统和电力系统运行方式及工况之间的密切关系,致使电力系统中PSS的协调设计和安装地点的选择成了PSS能否用于电力系统的关键。作者设计了一种调速侧电力系统稳定器,其设计原理和传统的PSS一样简单,且具有较好的鲁棒性,同时还具有多机解耦特性,给本机带来阻尼的同时不会给其它机组带来负阻尼,避免了参数协调和安装地点的选择。最后利用算例仿真验证了调速侧电力系统稳定器不仅可以抑制低频振荡,还可以提高电力系统暂态稳定性。 相似文献
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针对各种新型墙材在使用过程中出现的质量问题,采用前期配制的低成本FA-GBS干粉砂浆进行改性.通过掺入低粘度的羟丙基甲基纤维素后,砂浆的施工和易性能得到了极大的改善,可以较好地克服新型墙材出现的墙体裂缝等问题. 相似文献
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《Computers & chemistry》1988,12(4):301-304
A versatile and accurate electronic thermometer is devised for interfacing to an Apple II+ microcomputer. Hardware and software details are presented and discussed. An application of the temperature data acquisition system is also given. 相似文献
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