Effect of polycarboxylate-type superplasticizer on the paste fluidity based on the water film thickness of flocs

The excess water film theory and the properties of flocs are integrated to examine the effect of the polycarboxylate-type superplasticizer on the paste fluidity.The theory states that excess water can surround the flocs rather than the particles and that the cell consists of a floc and a superficial water film.Experiments on limestone powder pastes were conducted to verify the theory.The superplasticizer dosage(sp%)and the water–powder ratio by volume(Vw/Vp)were systematically varied.A sedimentation balance method was used to measure the size distribution of the flocs in the limestone powder pastes.The water film thickness(WFT)of flocs was then calculated and shown to determine the paste fluidity.Based on this WFT of flocs,the effect of the sp on the paste fluidity was determined and then compared with the effect of water.     

滦河流域水资源可持续利用对策分析

随着人口增长和经济社会的快速发展,对资源需求量急剧增加,水资源短缺已成为严重制约滦河流域经济发展的重要因素。文中简要分析了滦河水资源开发利用中存在的问题,并从提高水的利用效率、调整产业结构、加强水利工程建设、完善水资源管理体系等方面提出了实现水资源可持续利用的对策。     

活性炭对原水中有机污染物去除效果的研究

文中针对原水水质特点,利用常规+活性炭吸附工艺对原水进行处理,着重分析了活性炭对有机物的去除效果。     

基于PLC和GPRS的供水管网监测系统

针对具体工程实例,分析了在供水管网监测系统中采用传统的无线电台等传输方式存在的缺点以及GPRS技术的优点,选用GPRS DTU作为无线监测设备,通过与单片机系统比较,选用西门子PLC S7-200作为现场数据采集设备。介绍了该系统的结构,硬件的选择,通信的实现,以及主要的监控功能,并说明实际运行三年来所显明的优越性。     

蒸发结晶操作中传热温差的选择

蒸发结晶是化工生产中常见的单元操作，在其加热过程中，较高的传热温差对于强化传热效率、提高设备能力极为有利。但是，传热温差过高会引起蒸发结晶操作的不稳定，甚至造成生产装置停车，使所追求的高效率适得其反。因此，必须合理选择传热温差，以保证生产装置在高效、稳定的状况下运行。     

氮磷钾高浓度烤烟专用肥

介绍硝酸铵－磷酸－铵－硫酸钾系高浓度烤烟专用复合肥的开发应用，三年的试验推广的实践证明，其肥效可与进口肥相媲美，配方合理，但价格比进口肥每吨低４００元左右。     

电去离子(EDI)技术在热电厂水处理中的应用

电去离子 (Electrodeionization简称EDI) ,是一种将膜分离技术与离子交换技术有机结合起来去除水中离子获得低电导率产品水的新型水处理技术 ,在电力、电子、医药、化工、冶金、机械、化妆品、电镀电解、食品饮料、纺织印染等多个领域具有广泛的应用空间 ,本文简要介绍了这种新型水处理技术的原理、特点及在热电厂化学水处理中的成功应用情况     

Theoretical comparisons of search strategies in branch-and-bound algorithms

Four known search strategies used in branch-and-bound algorithms-heuristic search, depth-first search, best-bound search, and breadth-first search-are theoretically compared from the viewpoint of the performance of the resulting algorithms. Heuristic search includes the other three as special cases. Since heuristic search is determined by a heuristic functionh, we first investigate how the performance of the resulting algorithms depends onh. In particular, we show that heuristic search is stable in the sense that a slight change inh causes only a slight change in its performance. The best and the worst heurstic functions are clarified, and also discussed is how the heuristic functionh should be modified to obtain a branch-and-bound algorithm with an improved performance. Finally, properties and limitations of depth-first search, best-bound search, and breadth-first search viewed as special cases of heuristic search are considered. In particular, it is shown that the stability observed for heuristic search no longer holds for depth-first search.     

FBG传感器在水下结构工程中的应用

近年来,光纤光栅传感技术在我国发展很快,已经在桥梁、土建等多个领域中得到了应用,但在水工领域的应用还很少.本文结合白鹤梁工程实例,探索该项技术在这一领域应用的可行性.开展的光纤光栅应变、温度传感器在水下工程领域中较大规模的应用研究结果表明：FBG具有很好的防水性能,测试精度高,长期稳定性好,信号传输距离远,为水下结构的长期监测提供了一种可靠有效的手段.