首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 187 毫秒
1.
The water supply system with pump-head tank joint water supply is a mature technology widely used in high-rise buildings. In recent years, with widespread of new type pipe material and decoration of buildings, there is insufficient pressure head of water supplied at top floors in high-rise buildings. In this paper from the experience in engineering practice the reason for this problem and its countermeasures are investigated, then some suggestions are given.  相似文献   

2.
王卫锋  杨晓青  张岁岐  山仑 《作物学报》2013,39(8):1462-1468
剪去小麦部分根系能瞬间打破其水分平衡,研究根系导水特性对剪根的响应有助于解释静水压对作物根系吸水的调节机制。通过对苗期小麦(Triticum aestivum)剪根与水分胁迫处理,用压力探针技术测定单根和细胞两种尺度上的根导水特性变化,以及根中TaPIP1;2和TaPIP2;5的转录调节变化。结果显示,剪根处理或水分胁迫处理使叶片蒸腾速率和气孔导度均显著低于对照,而单根导水率和细胞导水率均与对照无显著差异。剪根处理的叶片蒸腾速率、气孔导度、叶水势、单根导水率和细胞导水率均显著高于水分胁迫处理,而剪根且水分胁迫处理的各参数均显著低于其他处理。各处理的单根导水率与细胞导水率显著正相关。各处理根中TaPIP1;2和TaPIP2;5相对mRNA含量的变化规律与单根和细胞导水率的变化规律相似。剪根处理显著上调了TaPIP1;2和TaPIP2;5转录,水分胁迫处理显著下调了其转录,但TaPIP1;2和TaPIP2;5在剪根且水分胁迫处理中的转录水平最低。这些结果表明,小麦的根导水特性在单根尺度和细胞尺度上具有一致性;剪根短期内能够增加小麦幼苗的水分敏感性。推测TaPIP1;2和TaPIP2;5参与了静水压对小麦根导水特性的调节过程。  相似文献   

3.
The schemes of domestic water supply for a residential quarter of high-rise building are introduced.The energy consumptions of water supply schemes selected are compared and analyzed.The energy saving of the water supply schemes with water tank and variable velocity variable frequency pump are obtained.And demonstrated the domestic water supply system of combination the roof water tank and variable velocity variable frequency pump is good at energy saving.Furthermore,by the comparison of the investment and cost of these schemes in their lives,the best choice of domestic water supply system is gained.  相似文献   

4.
Energy consumption of water intake is one of the key factors for energy saving in the application of the open loop surface water heat pump system. An energy efficiency ratio coupling model for open loop surface water source heat pump systems was established on the basis of the energy consumption model for the water intake and the heat pump units. According to energy saving rate and regulation of energy consumption of water intake, dynamic temperature limits of water intake in different water supply temperature of cooling tower and different pump head were proposed so as to find a calculation method of temperature limits of water intake of open loop surface water heat pumps. Moreover, the energy saving rate of surface water source heat pump systems compared with traditional air conditioning systems under various condition was also calculated.  相似文献   

5.
针对节水微灌技术发展,研发出一种新型的负压渗灌系统。新系统将常规的环形管输水改造为直路单向输水,通过控制计量水箱结构和调压器实现了植物对水分连续自动获取,改变了传统的间歇灌溉理念,提高了灌溉精准和自动化程度,同时显著提高了水分利用效率,实现了作物自身需水情况与土壤水分平衡精准供水,促进了水分高效精准利用。负压自动补给灌溉具备节水、节能和保护农业生态环境、保护土地等农业自然资源等优点,从而实现土壤水分的精确和持续控制,使省工、省力、规模化、高效率和高科技的现代农业技术成为现实,彻底颠覆了传统滴灌方式的灌水理念,由人为机械供水改为由土壤水势实时平衡自动、实时、科学调控灌水量,具有广泛的开发前景。  相似文献   

6.
This paper introduces the metod of optimal design of municipal water distribution,The main points are the theory,mathematical model,program frame figure and example in practice of the optimal method of hydraulics.The program is applicable to the design and calculation of the pipe network in a city. It gives a simple and convenient calculation method for multiple-scheme design and scheme cmparison of water supply system.  相似文献   

7.
农业节水灌溉经济效益的分析和计算   总被引:7,自引:1,他引:6  
干旱缺水是制约农业生产发展的主要因素之一,而农业节水灌溉就是用尽可能少的水投入,取得尽可能多农作物产品的一种农业高效用水模式;对农业节水灌溉经济效益的分析和计算从理论上进行了系统的阐述,供相关人员参考。新疆生产建设兵团各垦区是荒漠、半荒漠人工垦荒绿洲灌溉农业区,缺水问题尤显突出。要使垦区农业经济健康持续稳定的发展,必须发展节水农业,提高灌溉水的利用率,提高单方水的生产效率,节水扩灌,改善农业生产技术措施,提高粮、棉、果、牧的产量和品质;只有通过农业节水才能满足“生态维护用水”的需求,防止生态脆弱区生存环境的进一步恶化,降低各种自然灾害(大风、沙尘暴、浮尘等)发生的频率,减少农田沙化的进度。  相似文献   

8.
In multistoried or the high-rise civil constructions the full-time machinery hot water circulation supply system design,whether the design parameters for the flow and the lift of circulating pump are appropriate or not,will be related to continuously,safe,stably running of the hot water supply system.This paper introduces parameter selections of hot water circulating pump both at home and abroad.Based on the difference of these selection means it analyzes the calculating means of the flow and the lift of circulating pump.Whether the circulator flow should join the additional circulating flow or not is the focal point in the argument.In China's present "Code for design of building water supply and drainage" the additional circulating flow is considered not flowing through the circulating pump,so in calculation the additional circulating flow does not contain the circulator flow.By analysis of the water distribution operating mode and various ring circuits difference,as well as considering that for the very small circulator flow it is more difficult to use the valve regulation and to achieve balance between various ring circuits resistance loss,inaccessible absolute circulation in the same regulation,short circuit and so on,the circulator flow should be the sum of circulating flow and additional circulating flow.To calculate lift head the additional circulating flow should be considered through the calculating loop.  相似文献   

9.
Chemical regulation using plant growth regulators has proved to be potentially beneficial in water‐saving agriculture. This experiment was conducted with winter wheat (Triticum aestivum L. cv. ‘Jingdong 6’) to study the effect of chemical regulation on alleviation of water deficit stress during the grain filling stage. Uniconazole, a plant growth regulator, was foliar sprayed at 85 % (adequate irrigation) and 60 % (deficit irrigation) field capacity. Results showed that the distribution of 3H‐H2O in roots and flag leaf, characteristics of vascular bundle in primary roots and internode below spike, roots activity, transpiration rate and stomatal conductance of flag leaf were negatively affected by deficit irrigation after flowering. Foliar spraying at the early jointing stage with 13.5 gha?1 uniconazole was able to relieve and compensate for the harmful effects of deficit irrigation. Both the area of vascular bundle in primary roots and internode below the ear were increased by uniconazole, while root viability and their ability to absorb and transport water were increased. In the flag leaf, stomatal conductance was reduced to maintain the transpiration rate and water use efficiency (WUE) measured for a single wheat plant was higher. Uniconazole increased WUE by 25.0 % under adequate and 22 % under deficit irrigations. Under adequate irrigations, the 14C‐assimilates export rate from flag leaf in 12 h (E12h) was increased by 65 % and 36 % in early and late filling stages, while under deficit irrigations, the E12h of uniconazole‐treated plants exceeded that of control plants by 5 % and 34 % respectively. Physiological damages caused by water deficiency during the grain filling stage of wheat was alleviated by foliar spraying with uniconazole.  相似文献   

10.
循环水养殖系统为当前水产养殖先进生产力的发展方向,其具养殖水环境高度可控、产品质量安全可靠、节水、节地等特点,符合国家转变经济增长方式,节能减排的战略需求。循环水养殖水净化装备是循环水养殖系统核心组成。其为循环水养殖生产中的水产养殖对象提供良好水生态环境,提高水产养殖品产量及质量,提升资源利用率。本文以循环水养殖系统水净化典型工艺为主线,对其主要环节包括悬浮物去除、溶解性有机物降解、杀菌消毒、增氧、调温等所涉及的装备技术进行探讨及总结,并提出发展建议,以期为精准、高效、节能循环水养殖系统构建,推进其进一步应用提供支持。  相似文献   

11.
The high elevated water tank of high rise building is an important part in thedesign of water supply system and fire water system in highrise buildings .The discussionsare presented in this paper about the necessity of high elevated water tank installation,thevolume of the tank and its installation height.  相似文献   

12.
密云水源地水环境承载力系统动力学模拟与预测   总被引:3,自引:1,他引:2  
水环境承载力作为人类活动与水环境系统的联系界面,是判断社会经济与水环境系统是否协调的尺度。针对密云地水环境承载力系统的复杂性,利用系统动力学的动态分析优势和政策实验室功能,建立水环境承载力系统动力学模型,构建指标体系,并结合层次分析法和水环境承载力量化方法,对2008-2020年水环境承载力进行模拟与预测,分析不同优化策略下水环境承载力变化特征。结果表明:(1)现状延续策略下,2008-2020年水环境承载力呈逐年略微下降的趋势;(2)开源、节流和治污、减排2种优化策略均能有效提高的水环境承载力,并且前者的提高幅度大于后者,而区域外调水措施则不能从根本上改善水环境承载力;(3)本地开源、节流措施与治污、减排措施结合后,可以大幅提高水环境承载力,是实现经济活动与水环境协调发展的最佳策略,进一步提出了该区域生态经济协调发展的策略和措施。  相似文献   

13.
In view of the different of the underground heat storage water tank of solar position arrangement, make use of the Fluent software program numerical simulation and calculation, it is concluded that under different conditions the heat storage water tank temperature field distribution of the soil around. At the same time, establishing physical model and mathematical model of underground heat storage water tank and combined with practical engineering, verify the underground storage tank for heat and energy storage, to obtain the relationship between the tank roof loss and total heat release. Calculation results show that under the same conditions, outdoor storage tank at the top of the heat dissipating capacity to reduce, so the method can be used to offset at the top of the energy required collector to reduce, so the method can be used to offset this part of the energy required collector area of the cut, improve thermal efficiency and reduce the user store hot water tank of the store.  相似文献   

14.
高产冬小麦节水栽培的叶水势特征   总被引:7,自引:1,他引:7  
马瑞昆  蹇家利 《作物学报》1995,21(4):451-457
田间和盆栽试验研究表明叶水势日变化曲线因供水和生育时期而不同,黎明前叶水势(ψ^pre)开花期低谷十分明显,与土壤水分动态变化不一致,午后叶水势表现为前期低中期高后期渐降的变化特点,不同水文年型间存在差异,生育中后期叶水势与深层土壤水分含量的相关程度增强,开花期叶水势与产量关系最为密切。前期控水式的节水栽培在一定程度上降低生育期叶水势,可通过渗透调节功能和较高膨压的维持稳定高产。  相似文献   

15.
The power consumption of frequency conversion chilled water pump of an office building regulated by constant pressure difference method with bypass valve is studied experimentally. A model of power consumption of chilled water pump is proposed. The effects of pressure difference set point of bypass valve on instantaneous and annual power consumption of chilled water pump are analyzed. The simulation results are validated experimentally, which shows that there is a maximum water flow rate which increases with the increase of the pressure difference set point of bypass valve at equilibrium state. There are three pressure operation regions of the bypass valve: under pressure region, constant pressure region and over pressure region. The power consumption of frequency conversion chilled water pump is affected by the pressure difference set point of bypass valve significantly, and it would be minimized as the pressure difference set point of bypass valve is equal to the pressure difference between supply water and return water of the farthest user.  相似文献   

16.
The one dimension mathematical model has been adopted to study the projects of the daily regulation of hydroelectric station: the implicit format of Preissmann has been adopted to solve the equation.The program of one dimension unsteady flow has been worked out.The result of calculation of the program has been verified by the result of the physical model and the coincide well.Under 4 kinds of projects of the daily regulation of Jinghong Hydroelectric Station,the unsteady flow conditions in lower reaches of the dam with the length of about 85km have been calculated by the program.The graph has been adopted to analyze the important characteristic parameters of the unstable flow conditions of 4 kinds of projects: the range of water level per day,the range of water level per hours and the range of water level per 20 minutes.Finally,the project of the daily regulation of Jinghong Hydroelectric Station which has a smallest influence on the navigable flow conditions has been obtained.  相似文献   

17.
农田深层土壤水利用现状与研究趋势   总被引:2,自引:0,他引:2  
近年来,由于水资源短缺,节水农业是华北平原的研究热点。笔者就农田深层土壤水的意义和国内外研究现状进行了综述,并提出了农田深层土壤水的研究趋势。在华北平原,应进行亏缺灌溉条件下周年农田深层土壤水利用效率的研究。  相似文献   

18.
A new type of energy efficiency control method for fan-coil unit is presented. By introducing the conception of duty ratio into electric valve control, the cooling and dehumidifying capacity of fan-coil unit is fully utilized. By means of Mamdani type fuzzy rule and the Method of Functioning-fuzzy-subset Inference, duty ratio of valve and fan speed signal are identified according to deviation and deviation change of room temperature. It is shown that presented method could achieve at least 30% energy saving than traditional control method as well as a preferable room temperature control effect.  相似文献   

19.
内源激素对作物高效用水的调控机理研究进展   总被引:2,自引:1,他引:1  
内源激素对作物高效用水有重要调控作用。此文系统论述了内源激素对作物高效用水的调控作用和机理,从水分利用效率的内涵、内源激素与作物叶片水平水分利用效率(WUEl)、内源激素与生物量水平的水分利用效率(WUEbm)、产量水平水分利用效率(WUEy)的关系等方面综述了国内外内源激素与高效用水的关系研究进展。在此基础上,提出了激素对作物高效用水调控研究中存在的问题,并探讨了今后的研究发展方向。  相似文献   

20.
高产冬小麦叶水势的变化特点与节水调控   总被引:5,自引:0,他引:5  
1986-1990四个年度研究结果显示,叶水势是变化困供水及生育时期而不同。黎明前叶水势随生育进程而变化,开花期出现明显低谷,与土壤水分动态变化不一致;午后叶水势具有规律的阶段性变化,且因不同水文年型出现间差异。叶水势与土壤含水量呈曲线关系,随生育进程,叶水势与深层土壤水分的相关性增强。开花期叶水势与产量关系最为密切。前控式节水栽培可通过渗透调节维持较高膨压而高产。提出了不同水文年型高产节水主要生  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号