Water hammer protection for diversion systems in front of pumps in long-distance water supply projects

For a water supply system with long-distance diversion pipelines, in addition to the water hammer problems that occur beyond pumps, the safety of the water diversion pipeline in front of pumps also deserves attention. In this study, a water hammer protection scheme combined with an overflow surge tank and a regulating valve was developed. A mathematical model of the overflow surge tank was developed, and an analytical formula for the height of the overflow surge tank was derived. Furthermore, a practical water supply project was used to evaluate the feasibility of the combined protection scheme and analyze the sensitivity of valve regulation rules. The results showed that the combined protection scheme effectively reduced the height of the surge tank, lessened the difficulties related to construction, and reduced the necessary financial investment for the project. The two-stage closing rule articulated as fast first and then slow could minimize the overflow volume of the surge tank when the power failure occurred, while the two-stage opening rule articulated as slow first and then fast could be more conducive to the safety of the water supply system when the pump started up.

Study on the Technology of Supplying Water Safely by Long-Distance Pipeline

The extensively built long-distance water transmission pipelines have become the main water sources for urban areas. To ensure the reliability and safety of the water supply, from the viewpoint of overall management, it would be necessary to establish a system of information management for the pipeline. The monitoring, calculating and analyzing functions of the system serve to give controlling instructions and safe operating rules to the automatic equipment and technician, making sure the resistance coefficient distribution along the pipeline is reasonable; the hydraulic state transition is smooth when operating conditions change or water supply accidents occur, avoiding the damage of water hammer. This paper covered the composition structures of the information management system of long-distance water transmission pipelines and the functions of the subsystems, and finally elaborated on the approaches and steps of building a mathematics model for the analysis of dynamic hydraulic status.

Dynamical variations in groundwater chemistry influenced by intermittent water delivery at the lower reaches of the Tarim River

The water of Bosten Lake was released to lower reaches of the Tarim River for 5 times from 2000 to 2002. The changes of total dissolved solid (TDS) and the major ions (SO2-4, Cl-, Na+, Ca2+, Mg2+ and HCO-3) were analyzed during this period. It was found out that TDS and the concentrations of the major ions initially and quickly increased and then decreased, but finally increased again. These changes were different at different distances from the river, which indicated that the groundwater changes relied on the distance from the river. In addition, the salt in groundwater was only diluted but not removed by the water. It was suggested that ecological measures should be sought to really promote the quality of the groundwater at the lower reaches of the Tarim River.

Urban Services Delivery in Limbo： A Provisional Assessment of Gweru＇s Water Supply System

This study sought to assess Gweru＇s water supply system from the source to the consumer to find out whether the water is safe for domestic purposes, mainly consumption. Water samples were taken from Gwenoro dam （raw water）, Gwenoro treatment plant （treated water） as well as from GIS-generated random points of residential areas closest to Gwenoro and furthest from both the dam and the treatment plant. These were taken for laboratory testing where parameters like pH, hardness, turbidity and DO （dissolved oxygen） were tested. Questionnaires were used to solicit the views of the consumers on water quality and water service delivery from eight randomly selected residential suburbs. Interviews were also administered to Gwenoro Water Treatment Plant superintendent and deputy to get insight into the day to day challenges that they have to grapple with. Results generally show that treated water from Gwenoro treatment plant is relatively safe to drink for those who have access to it. However, some consumer points like Mkoba 13 and Mkoba 18 receive water whose DO is out of the recommended range. Suburbs which lie on higher ground like Mkoba 19 and Mkoba 14 however rarely receive water from Gwenoro with some residents of Mkoba 19 having had no water from their taps for more than three years now. The study recommends that new equipment be bought for the treatment plant so that treated water reaches all parts of the city. Newly resettled farmers in the Upper Runde Catchment must be resettled elsewhere while urban stream bank cultivation must be banned to reduce water pollution as well as possible sedimentation of Gwenoro dam.

Evaluation of Water Delivery Performance of Nkhafi Irrigation Scheme in Dowa District, Malawi, Africa

This study evaluated the water delivery performance of Nkhafi irrigation scheme based on adequacy, water delivery efficiency, equity, dependability and irrigation efficiency. Primary data were collected from field measurements, scheduled interviews, group discussions and use of a structured questionnaire. CROPWAT 8.0 computer model was used to determine crop water requirements and irrigation requirements. The results revealed that adequacy, water delivery efficiency, equity, dependability and overall water delivery performance were (0.74;0.82), (0.70;0.80), (0.15;0.20), (0.11;0.21) and (0.80;0.80) for 2017 and 2018 seasons respectively. The scheme overall irrigation efficiencies were 20% and 25% for 2017 and 2018 respectively. These findings revealed that scheme users failed to deliver adequate and dependable water in an effective manner in both growing seasons. This occurred due to insufficient water supply, poor irrigation scheduling, lack of adequate knowledge and skills in operating and rehabilitating hydraulic structures, siltation and water losses through seepage in canals. Therefore, it is recommended that major maintenance works need to be done along the whole canal network in order to achieve good overall water delivery performance. Furthermore, farmers need to be trained in water management, sustainable agricultural production practices, operation and maintenance of irrigation structures. The study has provided an insight on the status of the scheme hence encouraging scheme users to improve water delivery performance.

大麻二酚递送体系的研究进展

大麻二酚因其在治疗疼痛、焦虑、神经及运动障碍等方面的作用而备受关注。但大麻二酚存在水溶性低、首过代谢效应及全身生物利用度较低的缺点,极大限制了它的应用。构建递送体系可改善大麻二酚的药代动力学特征和生物利用度。综述了近年来用于提高大麻二酚溶解性及生物利用度的递送体系,分析了聚合物颗粒、脂质体、醇质体及环糊精递送体系的优势与局限性,展望了大麻二酚递送载体的发展方向,为开发新的大麻二酚纳米制剂提供参考。

杏北油田掺水系统全流程能量优化方法的研究与应用

油田含水率的上升和产液规模的不断增大,导致集输能耗逐年增加,如何保持开发效益,降低集输能耗,成为高含水开发阶段面临的一大难题。随着节能工作不断深入,潜力已得到很大程度的挖掘,常规技术节能空间小,能耗管控压力大。因此开展能量系统优化技术研究,该方法转变原来区域优化的方式,统筹采油井、计量间、转油站、脱水站四个环节,通过确定末端能耗需求,逐级推导前端各环节能供给的方式,指导集输系统精细化、低能耗生产运行。杏北油田自2017年应用能量优化运行技术,由点及面逐步扩大规模,已实现水驱转油站全覆盖,截至目前累计节气5 621×10^(4)m^(3),节电3 275×10^(4)kWh,为油田集输系统降本增效提供了指导依据。

有压输水系统水锤防护方案探讨

水锤是有压输水系统中一种极为常见的现象,而长距离、高扬程和大流量输水项目的水锤防护,对工程运行安全显得尤为重要。通过对水锤现象的探讨,分析产生水锤的基本因素,梳理常见的水锤防护措施,提出针对不同情况应采取相应的水锤防护方案;对流速、管线布置、管材、管长和管道最大工作压力等设计参数分析,通过工程案例选取调流调压阀、两阶段缓闭阀、空气阀、空气罐、超压泄压阀、调压塔及增加机组转动惯量等其中适合工程实际的水锤防护措施,使系统水锤危害得到有效缓解,可为类似工程提供经验和借鉴。

早期饮水疗法联合集束化护理对无痛分娩产妇产后尿潴留及排尿效果与舒适度的影响

目的:分析早期饮水疗法联合集束化护理对无痛分娩产妇产后尿潴留及排尿效果与舒适度的影响。方法:选取2022年1月至2023年1月拟于徐州市妇幼保健院产科行无痛分娩的68例产妇,利用掷硬币法分为两组各34例。对照组采取传统产后护理,观察组采取早期饮水疗法联合集束化护理。统计并比较两组产后尿潴留总发生率、排尿效果(排尿时间、排尿次数、单次尿量、残余尿量)、舒适度评分(生理、心理、精神、社会文化和环境)差异。结果:观察组的产后尿潴留总发生率低于对照组(P<0.05),排尿效果优于对照组(P<0.05),护理后的舒适度评分高于对照组(P<0.05)。结论:早期饮水疗法联合集束化护理可以降低无痛分娩产妇产后尿潴留发生风险、强化排尿效果并提升舒适度。

泵站-水库原水调水系统经济运行方式优化

为提高泵站-水库原水调水系统中泵站的运行效益,最大限度降低输水系统的运行成本.通过分析该类输水系统特性以及供水方式,基于遗传算法构建泵站机组流量分配模型,优化分配泵站运行流量.在此基础上,考虑泵站时间维度上的运行方式,结合亳州加压泵站的工程状况和区域分时电价,以单位提水费用最小为优化目标,构建经济运行模型.将该方法应用于亳州供水工程,结果表明模型效果显著,并对历史运行区间内周期输水量进行离散计算,拟合得出周期内单位提水费用最低工况,进而对拟合结果进行分析.结果表明:所构建经济运行模型具有较好的适用性,可降低工程运行费用,为工程优化调度提供指导;受到泵站运行效率和分时电价的影响,泵站单位提水费用随调水量增加先降低后升高.

低位水囊引产联合硬膜外分娩镇痛提高产妇经阴道分娩率的效果

目的探讨低位水囊引产联合硬膜外分娩镇痛提高产妇经阴道分娩率的效果。方法选取本院56例足月分娩产妇为研究对象,随机分为两组,各28例。对照组采用硬膜外分娩镇痛,试验组采用低位水囊引产联合硬膜外分娩镇痛,比较两组的产程用时、产后出血量、母婴不良结局及分娩情况。结果试验组第一产程、总产程用时短于对照组,产后24h出血量少于对照组,差异有统计学意义(P<0.05);试验组母婴不良结局发生率为3.57%,低于对照组的21.43%,差异有统计学意义(P<0.05);试验组经阴道分娩率为75.00%,高于对照组的57.14%,差异有统计学意义(P<0.05)。结论联合应用低位水囊引产与硬膜外分娩镇痛可以有效缩短产程,降低产后出血和母婴不良结局风险,提高经阴道分娩率。

汪清抽水蓄能电站输水发电系统渗控效果数值模拟研究

抽水蓄能电站输水发电系统埋深较大,受排水廊道、隧洞充水、复杂地质条件、天然地下水等多种因素影响,常形成复杂渗流场。依托汪清抽水蓄能电站工程,基于FEFLOW建立包含输水隧洞、地下厂房、排水廊道、围岩、断层的三维渗流稳态模型,分析了沿输水发电系统纵剖面的渗流场分布特征,并对各部位的渗流量进行预测。根据模拟结果对初始方案进行优化,修改方案取消了不必要的中平段排水廊道,并抬升下平段排水廊道使其以自流方式排出渗水,厂房区排水廊道和洞室群渗流量合计8048.16 m^(3)/d,为地下厂房排水泵选型提供了较大富裕度。修改方案取得较好的防渗排水效果,对类似工程的渗控措施优化具有指导意义。

百里香酚单向输水抑菌垫制备及其对冷鲜马肉保鲜研究

为解决冷鲜马肉在贮藏过程中发生汁液流失,导致冷鲜马肉发生腐败变质的问题,该研究通过静电纺丝技术,制备出单向输水抑菌垫并应用于冷鲜马肉的保鲜实验中。通过扫描电镜、傅里叶红外光谱、缓释性能、单向输水性能和抗菌性能评价该抑菌垫对冷鲜马肉的保鲜效果。结果表明,百里香酚被成功包埋于上层纤维膜中并且具有缓释作用,对大肠埃希氏菌、金黄色葡萄球菌具有明显的抑菌效果[抑菌圈直径为(24.32±0.72)mm],水可以自发地从疏水层到达亲水层并且被吸收。将该抑菌垫应用于冷鲜马肉的贮藏实验中,单向输水抑菌垫对于马肉中菌落总数值、挥发性盐基氮(total volatile basic nitrogen,TVB-N)值的上升均具有明显地延缓作用,并且可以将马肉货架期延长6 d。该抑菌垫可以控制微生物生长繁殖所需水分并抑制微生物繁殖,因此,该抑菌垫可以有效延长冷鲜肉的货架期,为冷鲜肉的贮藏保鲜提供了一种新的方向。

自张式膨胀管技术的研究与应用

孔内膨胀管钻探技术是保障复杂地层孔壁稳定的有效技术之一。本文针对易出现缩径、坍塌、掉块的强水敏性地层,提出了一种自张式膨胀管护壁方法,并根据该方法的护壁原理研制了相适配的新型扩孔钻具、膨胀管及膨胀管投送装置,在不改变钻孔结构的情况下,对复杂孔段进行局部扩孔,投送膨胀管借助自身张力自然弹开而固定在相应的扩孔段,实现钻进时护壁。通过室内及现场试验对机具进行了优化,最终取得了良好的应用效果。试验证明:该方法操作简单可靠、易于定位,相较于水泥浆护壁具有处理速度快、停待时间短、减少重复处理等优势,适用于岩心钻探领域多孔段复杂地层的固壁与护壁,有利于降低孔内事故处理的成本、提高钻进效率,具有较好的推广应用价值。

塔里木河下游生态输水对柽柳种群适应更新影响的研究进展

塔里木河是我国最大的内陆河,其流域自上游至下游形成了以水为纽带的多元自然生态,但因地处干旱区,流域内生态脆弱,曾一度随着中上游地区人口增多与耗水的增加,大幅挤占下游生态用水,导致塔里木河下游常年断流,生态环境恶化,土地沙化严重。从2000年开始,我国大力实施生态输水工程,连续20年向塔里木河下游进行了人工间歇性输水,使下游地下水位明显抬升,荒漠河岸植被和物种多样性显著提高,对塔里木河下游生态系统的恢复和可持续贡献巨大。文章综述了生态输水工程实施以来,关于塔里木河下游柽柳种群的适应性更新和生理生态响应的大量研究,紧扣柽柳幼苗生长适应的特点和下游水盐胁迫的现实情况,探讨了塔里木河下游柽柳种群幼苗发生与生态输水漫溢的关系,分析了下游柽柳种群实生更新困难的原因,并在此基础上提出“强弱交替”的输水模式建议,以期更加有效地利用输水漫溢实现塔里木河下游柽柳种群实生更新的规模化,从繁殖生态学的角度降低种群衰退的风险,从而增强荒漠河岸生态系统的稳定性。

多阀门燃料输送系统复杂工况水击特性分析

针对某多阀门燃料输送管路系统工作过程中出现的不同阀门支路水击压力相互影响过大等问题,在充分考虑了系统快响应需求、轻量化及结构紧凑等约束条件下,通过试验研究了多阀门在复杂工况下的管路水击特性,包括管路中水击压力的变化与阀门脉冲工作模式以及同时工作的阀门组合之间的关系、水击压力与阀门打开-关闭时间间隔的关系,与阀门工作控制周期的关系以及与同时工作的阀门数量的关系等.在此基础上提出了基于多阀门工作模式调整的水击抑制措施,表明在不增加系统复杂度和重量的情况下降低燃料输送管路内水击压力是可行的.

干湿循环作用下渠道膨胀土裂隙演化规律及强度特性

为探究干湿循环作用下膨胀土渠道边坡裂隙演化特征与强度衰减规律,对北疆某渠道膨胀土开展了不同压实度的干湿循环试验,利用图像处理技术提取膨胀土表面裂隙参数,利用直剪试验测得膨胀土抗剪强度,并分析黏聚力随裂隙率的变化规律。结果表明:在干湿循环作用下,黏聚力的衰减速率随着压实度的增大而增大,内摩擦角总体呈减小趋势,裂隙率的增加速率随着压实度的增加而减小;裂隙相对面积呈先增后减的变化规律。最后,拟合获得不同压实度膨胀土黏聚力与表面裂隙率之间的关系式,通过确定膨胀土表层裂隙率可计算出其黏聚力。研究成果为进一步揭示剧烈干湿变化诱发的膨胀土渠道边坡失稳破坏提供了重要依据。

闸墙长廊道侧支孔船闸阀门运行方式优化试验研究

船闸阀门开启时间对闸室通航效率、输水廊道压力和闸室停泊条件等产生影响,针对阀门运行方式优化问题,采用物理模型试验对船闸进水口水位、阀门段输水廊道压力特性、闸室和下引航道内船舶系缆力等水力特性进行分析,结果表明:闸室和下引航道内前横、后横和纵向3个方向的船舶系缆力均随阀门开启时间增大而减小,且纵向船舶系缆力大于横向船舶系缆力。随着阀门开启时间增加,充水时阀门段输水廊道压力先减小后增大,泄水时则逐渐增大。综合考虑当阀门开启时间为6 min时船闸整体运行效果较好,该成果可为实际船闸运行提供技术支撑。

大变幅流量下重力流系统末端调流阀流量特性选型研究

针对大变幅流量下重力流系统末端调流阀流量特性的选型问题,基于一维水锤理论,采用数值模拟方法,结合工程实例,从调流阀流量特性对稳态运行开度的影响、调流阀关阀水锤最不利流量工况确定、调流阀流量特性对关阀水锤的影响等3个方面,对线性型、抛物线型和等百分比型等3种流量特性进行比较研究。结果表明:①等百分比型流量特性更有利于调流阀在小流量工况的稳定运行。该工况下,等百分比型调流阀的稳态运行开度更大,可避免因开度过小导致的汽蚀和振动。②关阀水锤的最不利流量工况应考虑初始流量最小工况。该工况的调流阀前初始压力最大,关阀历时最短,阀前最大水锤压力往往最大。③等百分比型流量特性更有利于减小调流阀的关阀水锤压力。在相同的初始流量和关阀速率下,等百分比型调流阀的初始开度更大,实际关阀历时更长,在小开度区域的流量系数变化梯度更小,因而关阀水锤压力更小,更有利于管道安全。

南水北调中线输水调度预演系统研发及应用

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