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。     

以太网供电技术及受电端电路设计

为解决具有以太网接口的小型功率设备供电不便的问题,在分别分析IEEE 802.3af标准中的以太网供电系统构成、以太网供电传输方式、以太网供电过程及其他电气特性的基础上,提出了一种通过以太网获取电源的解决方案,并给出了详细的电路设计原理图。该方案可同时支持以太网供电输入和其他辅助电源输入,并可以同时输出3.3 V和5 V这2种电压供系统使用。测试结果表明,该设计方案具有较低的成本和较高的效率,能够很好地解决小型功率设备供电不便的问题。     

An MIP model to optimize a Colombian cash supply chain

Financial institutions operate a supply chain where only one product is moved across the network. Although the cash is kept in several nodes to service the demand of final customers, availability causes opportunity cost related with its investment options. When planning the inventory of cash that should be maintained across the network, transportation decisions are also expected to be made. Cash transportation has a high cost, associated with the high risk of theft. Increasing the inventory can reduce the need for transportation, but the opportunity cost can be very high. Moreover, the inventory is also related with the service level perceived for final customers; therefore because of low inventory some people are not able to make some transactions. The aim of this work is to find optimal decisions related with cash inventory and transportation across the network, trying to balance the cost of the service and the quality perceived for final users.     

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。     

石墨化炉的供电特点及发展趋势

通过对石墨化炉的特点及其供电方面的有关问题的分析，论述了石墨化炉供电的特点及其发展的趋势，并对石墨化炉在交、直流电源供电方面提出了看法，以不断提高石墨化炉供电的设计水平．     

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     

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.     

城市污水回用于电站锅炉补给水的动态模拟试验研究

用经深度处理后再经二级除盐系统处理的城市污水作为试验水源，动态模拟电站锅炉的运行工况，考查其在高温高压条件下水汽品质的变化情况。结果．表明：虽然经二级除盐处理后的再生污水，其水质指标完全满足锅炉补充水的水质标准，但在高温高压工况下仍有低分子有机酸等分解产物出现，故认为利用城市污水作为锅炉补给水水源仍需谨慎。