Improving Operation of Pressurized Irrigation Systems by an Off-grid Control Devices Network

Water demand in irrigation is expected to increase in the near future, and it will be seriously impacted by climate change, specifically in semi-arid areas. The increase of water demand, along with the reduction of water availability, can seriously intensify the frequency and magnitude of pressure deficits in pressurized irrigation networks, with dangerous consequences on the healthy crop growth and on the crop production. In this framework, the present paper investigates the contribution of a network of smart control valves, named GreenValve System (GVS, patented by the Politecnico di Milano), to improve the management of a pressurized irrigation system. The GVS is able to recover energy for its operation from the flow, to be remotely commanded and to introduce management logics based on real-time data in order to create a stand-alone real-time monitoring and control network. In the paper, specifically, a three-step general and replicable methodological approach for the definition of installation and operating conditions for these valves is proposed. The effectiveness of a specific management logic, allowed by the use of the GVS, to limit pressure deficit and failure occurrence in the network is discussed. Reference is made to a case study on a critical on-demand irrigation network. The results showed that the introduction of simple management rules can reduce and even avoid the occurrence of hydrant failure, creating the conditions for more effective use of the resources.

     

Downstream Ecological Impacts of Controlled Sediment Flushing in an Alpine Valley River: A Case Study

Sediment flushing may be effective to tackle the loss of reservoir storage as a result of siltation. When operationally possible, the impact of this practice on the downstream aquatic environment can be mitigated by limiting the sediment concentration of the discharged waters (controlled sediment flushing). However, this topic is poorly documented, and concerns arise when limits are discussed. We present the results of a 3‐year field investigation concerning the controlled sediment flushing of a small reservoir on the Adda River, the main tributary of Lake Como—Italy. Two limits for suspended solid concentration (SSC) were adopted: 1.5 g L^?1, as average value throughout the whole working day, and 3.0 g L^?1, as alert threshold to adjust the ongoing activity. These constraints were essentially fulfilled in the course of the documented operations. The first year sediment flushing was more significant than the following year: 25 000 tons of fines below 2 mm in diameter were flushed in six non‐consecutive days in summer 2010, while, one year earlier, 75 000 tons were flushed in 16 non‐consecutive days. In the third year of investigation (2011), no sediment evacuation took place. The benthic macroinvertebrate and the fish communities were surveyed a short distance below the reservoir, that is, in the potentially more affected river reach. Clear pieces of evidence of environmental quality degradation were not detected; the adopted strategies can therefore be considered to be appropriate when planning sediment flushing management in comparable contexts. Copyright © 2014 John Wiley & Sons, Ltd.     

Rational Pricing of Water as an Instrument of Improving Water Use Efficiency in the Agricultural Sector: A Case Study in Gujarat,India

The agricultural sector in India accounts for over 85% of the total water used for various purposes in the country. However, the efficiency of water use in agriculture is very low, approximately 40% for surface irrigation and 60% for groundwater irrigation. Part of the reason for the low efficiency is the highly subsidized price of irrigation water that encourages the excessive application of water to crops. This paper is based on a case study conducted in the command area of a public irrigation canal in the state of Gujarat, India. It attempts to explore the role of the rational pricing of canal irrigation water in motivating farmers to use water judiciously and thereby enhance the water use efficiency in irrigated agriculture. The paper contends that farmers are sensitive to an increase in irrigation water charges, but unless the administered price is increased to the level that would prevail in a free market, it will not have its intended effect on irrigators.     

呼图壁河渠首工程水库泄空冲沙研究

对于多沙河流上水库的排沙方法,前人已有较多研究,但通过模型试验来模拟水库高淤积后的排沙研究较少。通过水工动床模型试验,对呼图壁河渠首拟建水库高淤积状态下的泄空冲沙进行了研究,根据冲淤前后的断面变化情况,对泄空冲沙过程中的溯源冲刷和沿程冲刷进行了分析,找出了泄空冲沙的规律及运用原则。通过对泥沙冲淤的数值分析,建立了溯源冲沙的概化图形,推导出了一套适合该水库的泄空冲沙公式。经验证,建立的泄空冲沙公式可以用于呼图壁河渠首工程水库排沙形态预测及排沙量的估算。     

灌区多孔质生态河床的改良及净污效果试验研究

将多孔质生态河床技术引入生态型灌区受损水体修复中．在冬季低温条件下，通过室内试验，延续了前期研究，采用仿生植物填料丝改良了块石多孔质生态河床，并与碎石多孔质生态河床对比，分析了两种河床模型对污染水体的净化效果．结果表明：采用仿生植物填料丝改良的块石多孔质生态河床是修复受损水体较理想的方法，它可以有效地降低由于水力条件的改变对河床的扰动，减轻由于底质污染物向上覆水体的再释放而导致的二次污染程度，还有利于增加河床的比表面积，增加微生物的数量和种类，提高河流的自净能力．此外，对比分析了两种河床模型对TP，TN、NH4^＋-N和CoDMn去除机制．     

耐蚀抗裂剂对提高混凝土耐久性的试验研究

处于海洋环境中的混凝土结构易受硫酸盐、氯离子等多种侵蚀介质侵入,产生物理和化学反应而逐渐破坏。通过对混凝土耐蚀抗裂剂混凝土的工作性能、力学性能及耐久性与同级配的普通硅酸盐水泥混凝土的性能进行对比分析,分析混凝土耐蚀抗裂剂对混凝土耐久性的影响。     

花岗岩沥青混合料水稳定性能改善试验研究

花岗岩是一种酸性石料,它具有强度高,耐磨性等优点.但是由于花岗岩和沥青的粘附性不好,往往因为达不到相应的设计要求而影响到花岗岩沥青混合料的运用.本文通过对掺加消石灰、水泥、改性剂、消石灰水代替矿粉等处理方法进行对比试验研究,探索改进花岗岩沥青混合水稳定性的最优方法,以期为工程实践提供借鉴.     

提高冷却循环水功效浅见

工业生产对冷却循环水提出了较高的要求，为了提高冷却循环水水效，文中提出了五个方面的改进建议，并做了较具体的阐述。     

基于MICP技术改良的膨胀土膨胀特性试验研究

为了探究微生物诱导碳酸钙沉淀(MICP)技术改良膨胀土膨胀特性的效果和作用机理,利用产脲酶菌CGMCC 1.368 7,开展了MICP拌和法处理膨胀土的膨胀特性试验。通过正交试验研究了反应液配比和Ca²⁺浓度对MICP拌和法处理膨胀土自由膨胀率、无荷膨胀率、CaCO₃百分生成量的影响及其变化规律,揭示了MICP改良膨胀土的微观机理。结果表明:经MICP拌和法处理后,膨胀土的膨胀特性得到显著改善;当反应液配比为1∶1、Ca²⁺浓度为2.0 mol/L时,膨胀土自由膨胀率最大降低了44.4%;当反应液配比为1∶3、Ca²⁺浓度为2.0 mol/L时,体膨胀率减小了92.2%,膨胀含水率降低了24.9%。MICP技术通过胶结土颗粒、充填土体孔隙和离子置换作用,降低膨胀土颗粒的亲水性,减小土颗粒间的排斥作用,减弱膨胀土的膨胀势。研究成果验证了基于MICP技术拌和法改良膨胀土膨胀特性的可行性。     

宽级配砾质土击实性能改良试验研究

伴随着宽级配砾质土作为心墙防渗料在土石坝工程中的广泛应用,对其工程特性的研究已成为水利工程研究的热点问题。通过室内试验,研究了添加减水剂对宽级配砾质土击实性能改良的影响。通过轻型和重型两种击实方案,对比研究了未添加减水剂与添加减水剂下两种宽级配砾质土试样的压实特性,研究表明:添加减水剂的土样可以在较小的击实功下得到较大的干密度,并在一定程度上降低最优含水率。更多还原     

温州市区河道纳潮冲污试验分析

温州市区温瑞塘河污染已经影响到两岸居民的正常生活，为此对温瑞塘河进行引瓯江潮水冲污以改善其水环境的试验。3次试验结果表明，引潮冲污可以短时间内改善区域水环境，对河道水生动植物没有产生不利影响，但是泥沙淤积突出。     

大跨度主双曲钢管桁架天面结构安装实践

简要介绍了香港顺利村公园的主要支撑跨度为42m的大距度主双曲钢管桁架的施工安装的方法，通过预先的方案对比分析，找出了最佳的施工方法组合，使工程节了大量资金及时间，为类似的工程在施工方法的选择方面提供了有益的借鉴。     

提高泵站装置效率的方法与途径

泵站装置效率是反映抽水设备及泵站各部分效率的综合指标,阐述了提高泵站装置效率的一般方法与途径,同时结合在引滦入津工程大张庄泵站实际应用进行了分析总结。提高泵站装置效率分别从以下几个方面展开:提高水泵效率、动力机效率、传动效率、管路系统效率和进水池效率。     

利用废旧胶粉改善红黏土工程性质试验研究

随着废旧轮胎的日益剧增,回收利用率较低带来了严重的环保问题。利用废旧轮胎胶粉对红黏土进行改良,形成混合土。通过标准轻型击实试验、等效击实试验、直剪试验以及渗透试验,研究了不同胶粉掺量(0%,3%,8%,15%,25%)和不同含水量对混合土的击实特性、抗剪强度特性以及渗透性的影响。研究结果表明:①混合土的最大干密度比原状红黏土低,且胶粉的掺量越大,最大干密度越小;②胶粉掺量增大,标准击实试验的最优含水率增大,等效击实试验的最优含水率有减小趋势;③胶粉掺量不超过15%时,随着胶粉掺量增大,混合土的抗剪强度增大,内摩擦角增大,且出现应变硬化现象:④标准击实下,胶粉掺量为8%时,混合土的渗透速率变化不明显;但胶粉掺量增加到15%时,混合土的渗透速率显著提高,提升幅度达到97.3%。研究成果可为贵州地区今后废旧胶粉的循环利用和胶粉改良红黏土的工程运用提供参考。     

水库补偿效益分配问题研究

水库补偿效益分配的步骤:一是确定水库补偿效益的施益方和受益方;二是计算水库补偿效益值;三是选择科学合理并能使各方较满意的分配方法.在分析水库补偿效益不确定性、可变性和博弈性的基础上,探讨了梯级水库串联式发电和并联式水库发电补偿效益影响因子的识别方法.水库补偿效益的分配方法主要有多目标综合分析法、模糊综合评判法、熵权法、离差平方法等,但都存在不足,需要进一步研究完善.     

Improving the Performance Efficiency of the Power Units of Thermal Power Plants

The importance of improving the performance efficiency of the thermal power plants is ever-increasing. This is caused by a number of factors. One of the mo     

双库连通水库调洪演算的方法研究

该文以合肥市杜集水库为例,分析和研究双库连通水库受下游河道影响的调洪演算的理论方法,通过建立双库连通水库计算模型进行调洪演算;计算结果表明,该方法理论合理,操作性强,成果可靠,可应用于双库连通水库的防洪调度和调洪演算。     

掺粉煤灰(FA)和复合外加剂(CSP-2)改善水工混凝土性能的试验研究

1　概述我单位组织有关技术人员 ,在专家、教授的指导下 ,历时两年 ,对“掺粉煤灰和复合外加剂改善水工砼性能”进行试验研究。研究成果已应用于中山市东河水利枢纽工程。实践证明 ,采用此法可以明显改善水工砼的性能 ,且对水工大体积砼的温控和经济性有积极意义。2　掺粉煤灰对水工砼性能的影响2 .1　掺粉媒灰可以明显改善砼的工作性粉媒灰致所以能改善砼的工作性是因为 :①优质Ⅰ、Ⅱ级粉煤灰其外形呈玻璃球状 ,在砼内起滚珠轴承作用 ,减小水泥颗粒之间的摩阻力 ,提高砼的工作性。②粉煤灰表观密度约为水泥的 0 .7倍 ,若实行等质量替代 ,…