森兰系列变频在循环投切恒压供水系统中的应用

多泵变频恒压供水常用的两种方案，比较了两种方案的优劣。重点介绍多泵变频恒压供水循环投切的控制过程，以实例说明循环投切方案的可行性。     

应用森兰变频器的自来水厂恒压供水系统解决方案

当前变频技术已广泛应用于自来水厂的恒压供水系统中,对于多泵配置,通常有两种不同的控制方案,即”顺序控制”方案和”循环投切”方案。本文着重介绍后者,描述了”循环投切”的工作过程和对变频器和电机的影响,最后给出了应用实例。     

由PLC控制的新型全自动变频恒压供水系统

介绍了一种已投入使用的基于PLC的恒压供水系统的构成和工作原理。系统采用变频调速方式自动调节水泵电机转速或加、减泵。改变以往“先切先投”方法,实现无冲击切泵,使水压过渡平稳。变频器故障时仍能自动运行,保证不间断供水。同时,故障消除后自启动,为“无人值守”全自动运行创造了条件。     

高层住宅变频调速恒压供水系统设计

结合一工程实例,介绍了PLC控制的变频调速恒压供水系统的工作原理及其特点;探讨了主副泵切换的阀值流量、阀值频率;并时住宅建筑变频调速恒压供水系统存在主泵不能自动切换为副泵工作的问题,提出了引入流量控制元的改进方法。实际运行表明:该变频调速恒压供水系统可进行主副泵切换,运行可靠且节能。     

基于水泵轴功率的变频恒压供水系统泵组控制研究

变频恒压供水系统能够根据水负荷变化自动调节水泵转速或切换水泵运行的台数,有效节约了电能,同时实现了水泵的软启动。通过分析变频恒压供水系统特点,提出基于水泵轴功率的变频恒压供水系统泵组控制方式,设计了一套以可编程逻辑控制器PLC为控制核心,结合变频调速技术和PID调节等技术的自动恒压变频供水系统。该供水系统能够有效地避免人为操作的复杂性且控制简单可靠。     

变频调速恒压供水系统新方法

针对当前多数恒压供水系统水泵运行状态单一、不能自动完成多台水泵循环工作,影响水泵使用寿命且使其它水泵长期停歇造成资源浪费的问题。提出了采用支持图形化逻辑电路编程的LOGO!可编程控制器,依据增泵条件和减泵条件,实现了变频恒压供水系统多泵自动循环工作和定时自动切换的控制功能。实际运行结果表明,该方法控制有效,系统运行稳定可靠、功能完善。     

一拖二变频调速恒压供水在中频炉冷却系统中的应用

详述了一种基于DP通信的一拖二变频调速恒压供水在中频炉冷却系统中的实现。该系统根据管网压力信号变频器动态调泵的运行状况,实现变频无极调速。通过plc与变频器的通信数据,控制工作泵数量的增减,真正做到用水和供水的动态平衡。     

恒压供水模糊控制应用

针对传统PID控制变频恒压供水系统稳定性差、参数调解困难的情况,利用DB-2000控制器的模糊控制功能,改进变频恒压供水系统。运行结果表明,改进的控制系统响应快、泵切换时管网冲击小,水压稳定,且系统可靠,节能效果显著。     

煤矿乳化液泵变频/工频切换控制

针对煤矿乳化液泵站采用变频器"一拖多"的多泵联动方案时存在冲击电流大的问题,提出了乳化液泵变频/工频异步切换和同步切换控制方案。现场试验结果表明,变频/工频同步切换控制能更有效地避免冲击电流,真正实现乳化液泵变频至工频的无扰切换。     

工作面泵站变频恒压控制系统

<正>由天地(常州)自动化股份有限公司研制推出的工作面泵站变频恒压控制系统主要针对工作面的乳化液泵、喷雾泵进行控制,实现乳化液泵的变频软启动、按需恒压供液、智能轮换调度、自动配比乳化液、自动补水补液,并控制喷雾泵与采煤机进行联动,实现整个工作面泵站控制系统的远程监控。该系统功能特点:1根据支架用液量,自动调节乳化液泵转速;2除可人工就地启停单台泵外,还可根据工作面是否用液自动启停     

Water resources

Abstract

Water, which was taken for granted and assumed to exist in abundance, has become one of our most precious natural resources. Hence hydrological and water management problems represent key areas of applied science in the current worldwide economic and ecological situations. Satellite remote sensing technologies have been used more and more to satisfy urgent requirements for information relating to water resources. Many efforts have been undertaken in Europe to develop appropriate methods and to advance these systems to an operational level. Main emphasis is given to processes in which land surfaces and inland waters are involved, dealing with the estimation of precipitation, the assessment of soil moisture, surface runoff and the forecasting of runoff, be it from rainfall or from snowmelt. Remote sensing methods are of fundamental importance for soil moisture monitoring on a global and on a regional scale. Experimental research has demonstrated that if, in principle, observations in the visible and thermal infrared regions of the electromagnetic spectrum are able to detect the surface moisture of bare soils, microwave sensors are the most promising tools for quantitative estimates of this parameter. A valuable amount of research on this subject has been performed in Europe and is reviewed within the framework of the most advanced international research. Within Europe regional or local aspects and problems dominate. Therefore the efforts and achievements concerned with these areas and applications, and the progress towards operational use, will be focused on primarily. The most advanced and most promising operational applications exist in the field of snow hydrology to improve power production.     

流水魔法

有道是：落花有意,流水无情。如果看字面意思的话,现在要有人站出来反对了,在近期法兰克福国际卫生洁具及供暖空调博览会上,水流像瀑布一般从水管里倾泄而下并且能够随水温变化颜色,三向反射水龙头,以及另一些独特有趣的创新,都让人们大开眼界。当坐在温暖的浴池中,看着仿佛溪流、飞泉的水链从空中划过,或许真的能令人忘情都市、寄情山野。之前的话确实说得太绝对了,     

水源地供水智能调度与远程管理的研究与实现

在研究工业园水源地供水过程的基础上,提出综合应用PLC技术,计算机技术,通讯网络技术和过程控制理论,进行供水系统技术升级改造,实现供水的智能调度,远程管理,为达到供水无人值守打下基础.     

水厂供水调度辅助决策系统

本文介绍了水厂供水调度决策系统的构成及功能,详细阐述了软件的实现原理,并概述了此软件具有一定的社会经济效益。     

Water glass bonding

The author developed a low-temperature (80°C), low-external loads (electric field, magnetic field, load, etc.) bonding technology using water glass which is used in making molds (silica sand). The adhesive area ratio attained by this bonding technology was more than 95% and the bonding strength was about 290 kgf/cm². As this water glass bonding technology is applicable at comparatively low-temperatures, the residual stress of the bond is so small as to be able to bond eight 4-inch wafers together in the 3rd dimensional direction. In addition, as the thickness of a bonding layer is as small as several nanometers, the precision bonding of a tolerance of ±3 μm was also possible through alignment, and we could successfully fixed a cap with having a bonding seal of 0.32 mm wide in the vacuum. The leak rate was less than the detection limit of the He leak detector (1×10⁻¹⁰ Pa m³/s), showing excellent air-tightness. Using this bonding technology, the author made a self-package type IR microsensor on an experimental basis, and carried out an accelerated environmental test. As a result, its MTTF (mean time to failure) was estimated to be 6 years.     

水源地图

美国一家名叫“人口行动”的私立机构进行的报告显示：现在世界上有三亿三干五百万人没有足够的水,这些人主要分布在非洲或中东的28个国家。现在有些国家,例如埃及、荷兰、柬埔寨、叙利亚、苏丹和伊拉克等,60％的纯净水是从国外进口的。全世界每五个人之中就有一个人无法得到安全饮水保障。     

水上行走机器人

水上行走机器人仿生水黾,利用液体的表面张力在水面上站立和行走,是近年来机器人研究领域新出 现的研究方向．本文综合分析了水上行走机器人相关理论与技术及系统研制等方面的国内外研究现状,并对该领域 未来的研究重点、关键技术和发展方向进行了展望．     

免耕措施对土壤水分及利用效率的影响

免耕覆盖能有效地控制土壤侵蚀,抑制地表起沙,防治土壤退化,将是我国北方地区代替传统农耕的最好办法之一。针对土壤水分往往是我国北方地区农作物生长重要的限制性因子,本文选择国内外免耕措施的土壤水分试验研究进行总结,系统地分析了免耕与传统农耕的土壤水分动态变化特征,评价了免耕土壤水分利用效率。结果表明,与传统耕作相比,免耕普遍可增加土壤水2%~8%,但只有长期实施免耕和覆盖达到一定程度时,免耕的增水效果才明显,而免耕水分利用效率却因产量、降水等而不同。     

Wheat Self-Sufficiency,Water Restriction and Virtual Water Trade in Iran

Sustainable food security is one of the policy-making targets in Iran, but water scarcity has always been a challenge to its actualization. Regarding this point, offering policies to address this challenge is essential. On the other hand, wheat is the most important commodity in the food baskets of Iranians, and due to the lack of equality in the supply and demand among the regions, a large amount of wheat is displaced every year. The displacement of wheat has resulted in virtual water trade among the regions and could be a possible solution to manage the water crisis in Iran. With respect to the necessity of research, the present study investigated the effects of economic policies on virtual water trade for wheat using a spatial equilibrium model. Therefore, the aim of this study was to investigate the pattern of virtual water trade flow and welfare changes which resulted from making different economic policies in the wheat market. The results showed that the wheat self-sufficiency policy reduces the total amount of virtual water trade, and will increase pressure on the water resources of Iran. The policy of paying tax and receiving subsidies also significantly affect the flow of virtual water trade. But that happens best when tax revenues are equal to the payment of subsidies.

     

水务一体化管理在平遥城乡供水实践中的应用

在阐述了平遥县实行水务一体化管理现状的基础上,结合供水企业的发展实践,从供水与需水、市场拓宽、水资源优化和供水企业自身发展等方面进行总结和分析,得出了水务一体化是实现供需双赢、拓宽城乡供水市场、提高供水企业生机和活力的体制保证,也是县域供水行业快速发展的根本出路。