Drainage of ascites in cirrhosis

For cirrhotic refractory ascites,diuretics combined with albumin and vasoactive drugs are the first-line choice for ascites management.However,their therapeutic effects are limited,and most refractory ascites do not respond to medication treat-ment,necessitating consideration of drainage or surgical interventions.Con-sequently,numerous drainage methods for cirrhotic ascites have emerged,including large-volume paracentesis,transjugular intrahepatic portosystemic shunt,peritoneovenous shunt,automated low-flow ascites pump,cell-free and concentrated ascites reinfusion therapy,and peritoneal catheter drainage.This review introduces the advantages and disadvantages of these methods in different aspects,as well as indications and contraindications for this disease.

Theoretical Analysis and Experimental Verification on Flow Field of Piezoelectric Pump with Unsymmetrical Slopes Element

Regular valveless piezoelectric pumps have rectifying elements outside their chambers to produce net flow. These rectifying elements outside the chamber will increase the overall volume of the pump and prevent its minimization. Valveless piezoelectric pump with unsymmetrical slopes elements（USE）, proposed in this paper, differs from other valveless pumps in that it is easy to be minimized by developing the chamber bottom as such a rectifying element. In this research, the working principle of the proposed pump was analyzed first. Numerical models were thereby established and numerical simulation was conducted to the chamber flow field with the method of time-dependent velocity. The effects of the USEs on the flow field in the chamber were shown clearly in simulation. And the particular feature of flow field in the chamber was discovered. It behaves a complex flow field, in which strong turbulent occurs companying a lot of vortexes in different directions and different sizes. This feature is just opposite to what regular piezoelectric pumps expect： a moderate flow field. The turbulent flow could be used to have different liquids stirred and well mixed in the chamber to produce homogeneous solution, emulsion or turbid liquid. Meanwhile, numerical simulation also presents the effect of the angles difference of the two slopes upon the flow field, and upon the flow rate of the pump, which fits to the theoretical analysis. Experiments with the proposed pump were also conducted to verify the numerical results. In these experiments, six USEs with different slope angles were used for efficiency tests, which proved the validity and reliability of the numerical analysis. The data obtained from numerical analysis agree well with that from the experiments. The errors ranged from 4.4% to 14.8% with their weighted average error being 9.7%.

Analysis on Flow Field of the Valveless Piezoelectric Pump with Two Inlets and One Outlet and a Rotating Unsymmetrical Slopes Element

Typically,liquid pump and liquids mixer are two separate devices.The invention of piezoelectric pump makes it possible to integrate the two devices.Hower,the existing piezoelectric mixing-pumps are larger because the need the space outside the chamber,and another shortcome of them is that they cannot adjust the mixing ratio of two liquids.In this paper,a new piezoelectric pump being capable of integrating mixer and pump is presented,based on the theory of the piezoelectric pump with the unsymmetrical slopes element（USE）.Besides the features of two inlets and one outlet,the piezoelectric pump has a rotatable unsymmetrical slopes element（RUSE）.When the pump works,two fluids flow into the inlet channels respectively.Then the RUSE controls the ratio of the two flows by adjusting the flow resistances of the two inlet channels.The fluids form a net flow due to the USE principle,while they are mixed into a homogeneous solution due to strong turbulence flow field and complex vortices generated by RUSE in the chamber.And then the solution flows through the outlet.Firstly,the theoretical analysis on this pump is performed.Meanwhile,the flow field in the chamber is calculated and simulated.And then,the relationship between the flows of the two channels and the rotating angle of the RUSE is set up and analyzed.Finally,experiment with the proposed pump is carried out to verify the numerical results.A RUSE with 20° slope angle is used in the experiment.Four sets of data are tested with the RUSE at the rotating angles of 0°,6°,11°,and 16°,respectively,corresponding to the numerical models.The experimental results show that the empirical data and the theoretical data share the same trend.The maximum error between the theoretical flow and the experimental flow is 11.14%,and the maximum error between the theoretical flow ratio of the two inlets and the experimental one is 2.5%.The experiment verified the theoretical analysis.The proposed research provides a new idea for integration of micro liquids mixer and micro liquids pump.

Erosion characteristic of slope sandstone soaking in acid mine drainage

Acid mine drainage（AMD） is one of the main reasons of slope instability in chemical mines with high sulfide. The pH values of the solution inside the mining pit decrease with the increasing of distance from ore body and vary from 1.2 to 4.6, according to the results of the water environmental investigation and the composition test of the slope sandstone in Xinqiao Pyrite Mine. Comparative experiments between original sandstone and AMD eroded sandstone samples show that after AMD erosion the uniaxial compressive strength and elastic modulus decrease by 30%-50% and 25%-45%, respectively, the cohesion and internal friction angle decrease obviously, and the Poisson ratio fluctuates between 0.20-0.29. The greater joints development, the higher residual stress after peak value, and the longer time to damage. Besides above, the reaction mechanism analysis of AMD eroded sandstone shows that the fillings in joints and fissures of sandstone are frequently decomposed and polyreacted, resulting in changes of interior molecule structure and fi＇amework composition, and decreases of cohesion and angle of internal friction between rock structure interfaces.

Effects of 946-nm thermal shift and broadening on Nd^(3+):YAG laser performance

Spectroscopic properties of flashlamp pumped Nd^3＋：YAG laser are studied as a function of temperature in a range from-30℃ to 60℃. The spectral width and shift of quasi three-level 946.0-nm inter-Stark emission within the respective intermanifold transitions of ^4F3/2→^4I9/2are investigated. The 946.0-nm line shifts toward the shorter wavelength and broadens. In addition, the threshold power and slope efficiency of the 946.0-nm laser line are quantified with temperature.The lower the temperature, the lower the threshold power is and the higher the slope efficiency of the 946.0-nm laser line is,thus the higher the laser output is. This phenomenon is attributed to the ion-phonon interaction and the thermal population in the ground state.

Experimental Study of the Pressure Fluctuations in a Pump Turbine at Large Partial Flow Conditions

Frequent shifts of output and operating mode require a pump turbine with excellent stability. Current researches show that large partial flow conditions in pump mode experience positive-slope phenomena with a large head drop. The pressure fluctuation at the positive slope is crucial to the pump turbine unit safety. The operating instabilities at large partial flow conditions for a pump turbine are analyzed. The hydraulic performance of a model pump turbine is tested with the pressure fluctuations measured at unstable operating points near a positive slope in the performance curve. The hydraulic performance tests show that there are two separated positive-slope regions for the pump turbine, with the flow discharge for the first positive slope from 0.85 to 0.91 times that at the maximum efficiency point. The amplitudes of the pressure fluctuations at these unstable large partial flow conditions near the first positive slope are much larger than those at stable operating condtions. A dominant frequency is measured at 0.2 times the impeller rotational frequency in the flow passage near the impeller exit, which is believed to be induced by the rotating stall in the flow passage of the wicket gates. The test results also show hysteresis with pressure fluctuations when the pump turbine is operated near the first positive slope. The hysteresis creates different pressure fluctuations for those operation points even though their flow rates and heads are similar respectively. The pressure fluctuation characteristics at large partial flow conditions obtained by the present study will be helpful for the safe operation of pumped storage units.

合理确定排涝泵站规模的感潮河道模型试验研究

合理确定泵站规模一直是感潮河道排涝工程设计中的关键问题。通过建立物理模型,在选定的水文边界条件和相应工程运行要求下,对某感潮水系两座涌口泵站规模进行试验研究。试验发现,受限于河涌过流能力,泵站规模存在临界值,超过该值后,即使再进一步增加泵站规模,水位也不会继续下降;泵站抽排对某位置水位的降低效应与泵站和该位置之间的距离密切相关,距离越近,水位降低越明显。基于上述认识,通过试验确定了满足水位管控要求的两座泵站规模的合理组合:距离相对较远的温涌泵站为80 m3/s,较近的金紫涌泵站为130 m~3/s。试验方法和主要成果可为工程方案比选及优化提供重要依据,对类似河涌整治工程也具有一定的借鉴意义。

农田排水沟除草护坡及生态净化研究综述

对农田排水沟除草护坡及生态净化等方面的研究进行了综述,并对目前主要使用的除草技术,生态护坡技术,以及发展前沿的生态净化技术等方面的国内外相关成果进行总结归纳。然而这些方法都存在技术单一、影响环境等缺点,在对各影响因素的协同作用进行综合系统分析的基础上,提出新的解决思路。对沟道运行面临的问题与需解决的科学问题进行了探讨,旨在为现代农业灌溉排水区域建设提供参考。

基坑提前排水围堰渗流稳定及排水策略研究

围堰渗流及边坡稳定关系到围堰自身稳定以及基坑能否及时形成干地施工条件,极大影响到主体建筑物的工期。依托于澜沧江TB水电站围堰施工与基坑排水工作,对围堰防渗墙各施工阶段基坑水位骤降条件下的堰体渗流稳定与边坡稳定性进行了研究。结果表明:随着防渗墙的施工逐步完成,围堰体浸润线的再次稳定用时逐步减小,且基坑内外水位差更大的条件下浸润线稳定用时更长;在围堰防渗墙处于一期槽施工完成二期槽泥浆固壁条件下,若能控制基坑单次水位骤降不超过0.9 m,则堰体边坡能保持稳定,此时可允许基坑提前排水。在此基础上,对TB水电站基坑提前排水策略及方案进行了研究。研究结果可为类似工程提供参考。

“8”字形盘密封螺旋泵排液特性

圆盘密封螺旋泵具有排量大、磨损小、介质适应性强等优点,但其使用过程中存在振动大、不能实现完全的自驱动等问题。针对这些问题,提出“8”字形盘密封螺旋泵,基于其工作原理构建泵送过程的几何模型,建立“8”字形密封螺旋泵排液体积的数学模型,分析啮合副型面参数对排液过程工作特性的影响机制。结果表明:单个转动周期内螺杆增压段螺槽被密封盘分为两个腔室,“8”字形盘密封螺旋泵排液体积较同半径下的圆盘密封螺旋泵提高了约55.7%;排液体积随密封盘大圆半径、密封盘过渡圆弧半径、螺杆半径变化均呈近似正比例线性关系。

基于Java的排涝泵站站内优化调度软件开发

【目的】针对安装全调节轴(混)流泵的排涝泵站开发计算软件确定运行中的最优开机台数组合和各机组的叶片角度,以获得最高装置效率或最大流量。【方法】根据实测的扬程和电动机输入功率等运行参数,结合水泵性能曲线推算水泵流量和流道阻力参数,研究装置效率随叶片角度变化规律。以平均装置效率最高或总流量最大为目标函数,建立动态规划模型进行站内运行优化调度,获得最优的开机组合和运行机组的叶片角度。在集成环境IntelliJ IDEA下,采用Java开发了通用的可视化的计算软件。【结果】对某排涝泵站,通过软件获得并分析了装置效率随叶片角度(或流量)的变化曲线,给出了在Hsy=5.3 m条件下不同需要流量下的优化运行方案。当需要流量为32 m^(3)/s时,与各机组均以+1.0°叶片角度的简单决策方案相比,软件给出的优化方案装置效率提高了0.76%。【结论】实际工程应用表明所开发的软件性能稳定,计算精确,实用性强。

基于GIS和SWMM的西安市北郊片区排涝模拟与排水系统优化

为解决西安市北郊河道超载风险问题,通过SWMM和GIS技术构建管网-泵站-河道耦合模型,在不同设计降雨重现期(1、2、5、10、20、50年)下对该区域排水系统进行模拟,进而分析下游河道水位变化规律并提出雨水分流调配与调整泵站调度的协同优化措施。结果显示:在5、10、20和50年降雨重现期下,随着降雨峰值的到达,整个系统88%的排口都存在顶托现象,最长持续时间160min。在重现期为1、2、5和10年降雨条件下,协同优化的措施使得河道峰值流量分别下降了17.6%、4.9%、3.7%和2.6%,河道水位平均下降了35cm,排水系统的超载节点分别减少了16.7%、31.4%、34.2%和27.5%,超载管段的数量分别减少了25.0%、28.6%、30.8%和25.3%。

“数字孪生”灌排泵站的建设与思考

目前大中型灌排泵站基本建设了自动化控制系统,实现工程在线监管和自动化控制,但在信息感知、科学决策及智能化运行方面,管理水平还比较低。为适应国家信息化发展战略总体要求和水利改革的发展目标,大中型灌排泵站应基于日常管理需求,积极搭建数字孪生泵站管理平台,实现“四预”功能。本文结合某大型灌排泵站的信息化建设实践,介绍了数字孪生技术在泵站设计、应用和实践,为相关泵站管理单位信息化建设提供参考。

煤层气L型水平井电潜螺杆泵井清防砂工艺技术创新及应用

套管完井压裂投产的煤层气L型水平井出砂严重,倒置式电潜螺杆泵举升工艺受压裂砂影响故障频繁,影响了连续稳定排采,因此确定了倒置式电潜螺杆泵排采过程中由于压裂砂导致的故障点,并针对性创新应用了井筒内、导流罩及泵内清砂工艺技术,同时优化防砂管柱设计,确保了连续稳定排采。

某钼(铜)多金属矿排土场边坡稳定性分析

为了研究排土场边坡稳定性,以西藏天仁矿业有限公司邦铺矿区钼(铜)多金属矿排土场为研究对象。通过工程地质条件调研,并考虑自然工况、降雨工况、地震工况三种工况,最后采用极限平衡分析法中的简化Bishop法、Spencer法与Morgenstern-Prince法对该矿排土场边坡稳定性进行分析。结果表明:排土场1-1’剖面在自然工况、降雨工况及地震工况下以极限平衡法计算所得到的安全系数均大于规范值,据此排土场边坡处于稳定状态。研究结果对该矿其他排土场边坡稳定性分析提供一定的参考依据。

建筑给排水系统中减振降噪设计的优化及实施分析

为保证建筑给排水系统运行时的稳定性,降低给排水系统的噪声,文章对建筑给水泵房和排水系统中的减振降噪设计进行了深入探讨。首先,分析给水泵组和排水系统的噪声机理,指出给水泵组和排水系统在运行时产生的噪声来源及传播途径;其次,提出了给水泵机组和排水系统减振降噪的设计方案优化措施。为验证设计方案的有效性,以某住宅小区实际建筑为案例,对给水泵房及室内排水的减振降噪优化方案进行了实测分析。实测结果表明,优化方案可以有效降低给排水系统的噪声水平,具有较高的实践价值。

安徽省关闭煤矿资源调查及其综合利用研究

【目的】在煤炭资源持续高强度开发与能源供给侧结构性改革的背景下,安徽省关闭了一批资源枯竭、产能落后的煤矿,而关闭煤矿仍赋存有地下空间、遗煤、瓦斯、矿井水、土地与基础设施设备等资源,开展关闭煤矿资源再利用具有现实的工程价值和经济效益。【方法】统计自2013年以来安徽省59座关闭煤矿基础信息和再利用现状,分析关闭煤矿分布特征、遗留资源与再利用潜力;构建安徽省关闭煤矿数据库与WebGIS云平台,实现关闭煤矿信息查询分析与可视化;以潘一矿与石台煤矿为例,分别介绍遗留瓦斯抽采与半地下抽水蓄能的关闭煤矿再利用方案。【结果和结论】结果表明:安徽省关闭煤矿主要集中分布在两淮矿区,部分关闭煤矿关闭时间较短、遗留资源丰富、产权隶属清晰,再利用潜力较大;潘一关闭煤矿综合使用封闭墙压管抽采、原抽采钻孔抽采和地面钻井抽采的立体化遗留瓦斯抽采技术,实施关闭煤矿采空区“排水-抽采-利用”的一体化工程,3年内累计抽采瓦斯量4 840万m^(3)、发电8 590万kW·h、直接经济效益5 120万元,同时保障了相邻矿井的安全生产;石台关闭煤矿拟建设半地下抽水蓄能电站,地下空间可提供有效库容30万m^(3)、装机容量35 MW。案例分析表明安徽省部分关闭煤矿资源再利用在技术经济上具有合理性,但仍需开展进一步深入研究。

降雨条件下堆积体饱和-非饱和渗流场分析与稳定性演化

降雨是工程区域堆积体边坡失稳的重要诱因,如何评价降雨条件下饱和-非饱和渗流对堆积体边坡稳定性的影响,其挑战在于准确获取堆积体的非饱和渗流参数。以梅家台滑坡典型治理工程为研究对象,采用饱和-非饱和有限元分析,并基于监测资料对渗流场动态反演,准确获得了非饱和水力参数和边界水位,进而采用极限平衡法对滑坡稳定性演化分析。结果表明:坡体后缘补给水位在692.0~694.5 m内动态变化,在后缘补给和降雨入渗作用下坡体内地下水位变幅为3.0~12.0 m;排水措施实施后地下水位下降9.0 m,且变幅降为1.0~5.5 m,同时在暴雨条件下,滑坡中部堆积薄弱带暂态饱和区范围减小84.5%,坡脚饱和区也被抑制到一号公路以下,发挥了很好的排水降压作用;滑坡存在沿中部薄弱带浅层滑动、沿下部前缘浅层滑动、沿老滑带从一号公路剪出3种失稳模式,降雨入渗时稳定性明显下降,稳定系数分别降低至0.82、0.99、0.98,小于稳定安全系数1.05,综合治理措施下,稳定系数分别增加0.28、0.13、0.19,目前稳定系数分别为1.10、1.12、1.17,各个失稳模式稳定系数均大于稳定安全系数,滑坡处于稳定状态。研究成果可为类似工程治理设计和渗流稳定分析提供参考。

城市排水泵站水力特性及整流措施

为了解弧形进水箱涵城市排水泵站水力特性,探寻改善泵站内部不良流态的整流措施,采用数值模拟方法对城市排水泵站水力流态及整流措施进行研究,并通过物理模型对整流效果进行验证。研究结果表明:弧形进水箱涵城市排水泵站的前池存在主流偏斜与分离流动现象,前池主流集中在中上层,中下层出现大范围的立面环流,底层存在回流,进水池内流态紊乱并出现旋涡,导致水泵进水不够顺畅;设计优化的“方形立柱+组合横梁”的组合式整流措施能够改善前池和进水池的水力流态,前池内的偏流和分离流动消除,底层回流消失,进水池旋涡得到有效抑制,3台水泵进水流道入口流速分布均匀度分别提升了12.0%、8.7%、8.3%,入流速度加权平均角分别提升了7.08°、9.07°、11.40°。

LD端面泵浦Tm:SrF_(2)电光调Q激光器

高掺杂浓度的Tm^(3+)增益介质能通过交叉弛豫过程提高激光器的量子效率,但同时也会增加能量上转换带来的损耗,从而限制激光器效率的进一步提升。对Tm:SrF_(2)晶体的荧光特性以及激光性能展开研究。在激光二极管(LD)端面泵浦下,实现最大功率2.99 W的自由运转输出,激光器的泵浦阈值为0.89 W,中心波长1851 nm,斜效率高达82.1%。采用KTP电光调Q开关演示了Tm:SrF_(2)激光器的电光调Q输出特性。在500 Hz重复频率下,获得了1.02 mJ的最大单脉冲能量,泵浦阈值为2.01 W,最短脉冲宽度为45 ns,对应峰值功率为22.67 kW。实验结果表明,基于LD泵浦的Tm:SrF_(2)激光器具有非常高的效率,有望成为中红外光学参量振荡器(OPO)和光学参量放大器(OPA)的理想泵浦源。