A HYBRID MODEL FOR THE MERGING OF JETS IN A COFLOWING AMBIENT FLUID

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Operational Diagnostics of Hydraulic Units

An example of detecting a breakage of a coupler of a guiding apparatus blade of a hydraulic unit using a database and tools of a vibration measuring comple     

关于交通流无量纲参数的识别

本文在两个无量纲交通流动力学模型的基础上指出模型的无量纲参数不再是一组单一值，而是一个集合，同时提出利用合理参数集来识别模型的无量纲参数的方法。通过一个实例说明了合理参数集的存在性和无量纲参数识别方法的应用过程，该方法在参数识别中具有一般意义。     

不完全井渗流近似计算及其应用

本文介绍一种近似计算的解题途径:将定厚土层中的平面渗流看成是轴对称渗流的特例,用等效椭球井代替不完全井,把半无限透水土层渗流看成是定厚土层渗流的特例,结合数值计算和电拟实验成果返推逼近,得出适用于小贯入度的任意井径的轴对称不完全井渗流近似计算表达式。此外,本文将长列不完全井依次分成等阻抗长列完全井和单个轴对称不完全井两部分分别计算,列出长列不完全井的近似计算表达式。针对三维渗流计算和试验中不完全井列的处理以及渗流参数反求等问题,推荐了几种处理方法。     

Firms’ willingness to invest in a water fund to improve water-related ecosystem services in the Lake Naivasha basin,Kenya

A valuation scenario was designed using a contingent-valuation approach and presented to decision makers in business firms in Kenya’s Lake Naivasha basin to test how applicable a water fund might be as a potential financing mechanism for a payment for water-related ecosystem services scheme. The findings indicate that measuring a firm’s willingness to invest in ecosystem services could help determine whether a firm would invest and engage with other stakeholders to pool their investments in ecosystem services. Linking the institutional decision-making behaviour of a firm and its willingness to invest in a water fund is the novelty of this article.     

Numerical analysis of rapid drawdown:Applications in real cases

In this study, rapid drawdown scenarios were analyzed by means of numerical examples as well as modeling of real cases with in situ measurements. The aim of the study was to evaluate different approaches available for calculating pore water pressure distributions during and after a drawdown. To do that, a single slope subjected to a drawdown was first analyzed under different calculation alternatives, and numerical results were discussed. Simple methods, such as undrained analysis and pure flow analysis, implicitly assuming a rigid soil skeleton, lead to significant errors in pore water pressure distributions when compared with coupled flow-deformation analysis. A similar analysis was performed for the upstream slope of the Glen Shira Dam, Scotland, and numerical results were compared with field measurements during a controlled drawdown. Field records indicate that classical undrained calculations are conservative but unrealistic. Then, a recent case of a major landslide triggered by a rapid drawdown in a reservoir was interpreted. A key aspect of the case was the correct characterization of permeability of a representative soil profile. This was achieved by combining laboratory test results and a back analysis of pore water pressure time records during a period of reservoir water level fluctuations. The results highlight the difficulty of predicting whether the pore water pressure is overestimated or underestimated when using simplified approaches, and it is concluded that predicting the pore water pressure distribution in a slope after a rapid drawdown requires a coupled flow-deformation analysis in saturated and unsaturated porous media.     

Removal of mercaptans from a gas stream using continuous adsorption-regeneration

The removal of the mercaptan, 1-methyl-1-propanethiol, from aqueous solutions using a non-porous, electrically conducting carbon-based adsorbent (Nyex 1000) was investigated. The adsorption process was found to be rapid (equilibrium capacity achieved within 5 minutes) with low adsorptive capacity (of the order of 0.4 mg g(-1)) when compared with activated carbon. Electrochemical regeneration of the Nyex 1000 in a simple divided electrochemical cell within a sequential batch treatment unit restored 100% of the adsorbent's adsorptive capacity using treatment times as low as 20 minutes by passing a current of 0.5 A. The sorptive characteristics of a Nyex-water slurry were also modelled and investigated both in a bubble column and in a continuous adsorption-regeneration treatment system. It was demonstrated that the continuous removal-destruction system could achieve a step reduction in challenge gas concentration of approximately 75% for a period of 35 minutes with a current of 5 Amps. This was attributed to mass transfer enhanced by a combination of adsorption and chemical reaction with free chlorine species generated in the electrochemical process.     

小浪底工程进水塔4000kN门机设计特点

小浪底工程进水塔４０００ｋＮ门机起升吨位大、扬程高、跨度大、控制设备多、控制要求高、担负的作业繁重，因而设计难度大。文章重点介绍了采用折线卷筒多层缠绕技术解决大吨位、高扬程启闭机设计时应注意的问题，采用偏轨小车代替回转吊的优越性和超长偏轨梁与主梁的连接方式及上拱设计时应注意的问题，门机及自动抓梁和清污机的电器控制要求、安全保护措施，主、副司机室的控制分工和大车供电等方面的设计特点。     

Combined effects of coastal forest and sea embankment on reducing the washout region of houses in the Great East Japan tsunami

Coastal vegetation is widely recognized for its ability to reduce tsunami damage; however, coastal forests in large areas of the Tohoku and Kanto districts of Japan were destroyed by the Great East Japan tsunami on 11 March 2011. To elucidate the tsunami-mitigating effect of a coastal forest during a destructive tsunami, the combined effects of sea embankment and coastal forest were analyzed using post-tsunami survey data of the damage and a nonlinear long wave equation model that includes the breaking or washout condition of trees. The numerical simulations estimated that a 600-m-long coastal forest reduced the washout region of houses due to a 10-m-high tsunami at the coast by approximately 100 m, and the reduction achieved by a sea wall of approximately 5.4–6.4 m in height was approximately 560–1520 m. The height of a sea embankment or wall with sand dunes greatly affects the breaking condition of trees behind it by changing the tsunami flux overflowing the sea wall and the sand dune. For the combination of a sea embankment and a coastal forest during a destructive tsunami, the tsunami mitigation function of the coastal forest has an optimum value when the fluid force on the trees is strong but not strong enough to break the trees under the condition at which the tsunami overflows the sea embankment. At the investigated site, the effect of the coastal forest was larger than that of the sea embankment under optimal conditions. Thus, a coastal forest on a sand dune should be designed as a mitigation measure behind a sea embankment and optimally designed to protect the houses that are not protected from a tsunami by the sea embankment alone.     

THE OPTIMAL DESIGN BASED ON RELIABILITY OF WATER DISTRIBUTION SYSTEM BY LINEAR MODEL

In this paper, a new technique are developed for optimal design of water distribution system besed on reliability. It applies a linear programming algorithm to the optimal design based on reliability. Within a small optimal search step range,the objective function and constraints can be expressed in the first order Taylor-expanding form,and three sub-models (a steady-state simulation model, a reliability model and a linear optimization model) are linked each in optimal searches. Thus, a traditional non linear problem can be solved by a linear model, the computing burden is significantly decreased. Therefore, the linear optimal model developed by the paper has more practical significance.     

跨流域调水工程突发事件及应急调度措施研究

 跨流域调水工程规模大线路长,沿线可能存在多种复杂地质条件,地理环境和气象条件差异较大。当发生自然灾害、交通事故及其它突发事件时,要求紧急截断水流或短期内大幅度改变流量,及时控制突发事件造成的危害,通过有效的应急调度,保证工程安全、平稳和连续的输水运行。针对正常供水过程中可能出现的突发事件进行归纳分类,分别从水质安全、渠道及建筑物结构安全、设备故障和社会安全等4个方面提出相应的闸门应急调度措施。同时,提出应急调度的目标原则和技术思路,可为下一阶段深入研究提供技术铺垫     

窄缝式挑坎强化消能与体型问题研究

窄缝式挑流鼻坎是适用于狭谷高坝大流量泄洪的新型消能工。本文在总结窄缝式挑流消能工应用现状和消能特性的基础上，对窄缝式挑坎的体型进行了初步研究。就满足窄缝流态、消能效果好且经济合理的体型，提出了设计计算的初步方法。     

Analysis of the development of damage in a welded junction in the hot intermediate superheat steam duct of 800-MW generator units

Data from a metallographic study of a damaged weld junction in a hot intermediate superheat steam duct and a computational model for crack development (in the damaged zone) by a creep mechanism are described. Anumerical calculation confirms the possibility of crack development to the known final size over a time of approximately 15,000 h, which corresponds to the operating time for the steam duct from the last time it was inspected until the time of a through fault, under conditions such that a 2.5-mm-deep surface crack (with a length of ∼50 mm along the surface) had been overlooked during this last inspection. Translated from élektricheskie Stantsii, No. 10, October 2008, pp. 29–35.     

云南洛甸河径流量的时间特征分析

利用经验模态分解(Empirical Mode Deposition,简称EMD)及Pettit突变检验方法,分析了昭通地区洛甸河水文站1961~2014年的年均径流量、年最大径流量、年最小径流量序列变化的周期、趋势、突变规律。结果表明:洛甸河水文站年均径流量经过EMD得到3个IMF分量和一个趋势项,各IMF分量反映的周期为3,6.5a及17 a,趋势项表明年均径流量在1961~1980年存在上升趋势,1980年后存在下降趋势。最大、最小径流量分解得到4个IMF分量和一个趋势项,各IMF分量反映的小尺度周期信息为3,6.5 a及12~17 a,大周期尺度为27 a及45 a,趋势项RES反映序列呈现出明显的下降趋势,在1980年后下降趋势较明显。Pettit突变检验结果表明洛甸河年均径流量及年降水量在1986年存在一个不明显的突变点,最大、最小径流量的突变点可能发生在1991年附近。     

大通河流域径流变化及特征分析

根据大通河流域尕大滩和享堂两个水文站1952-2014年的逐月径流量资料,用不均匀性分析了径流量的年内分配情况,使用Mann-Kendall检验方法和Morlet小波变换对径流量突变和周期性分别进行了分析。结果表明:大通河流域的汛期主要为5-10月,尕大滩站和享堂站汛期径流量分别占全年的87. 81%和81. 9%。越向下游,大通河径流年内分配越均匀; 1991年之前,大通河上游和下游径流变化都呈下降趋势,1994年之后,上游尕大滩站径流量呈微弱的增加趋势,下游享堂站径流量呈快速下降趋势;上游尕大滩站径流量存在4、8、21a左右的周期震荡,下游的享堂站径流量则存在着3、6、31a左右的周期震荡; 1994年之前径流主要受气温和降水等气象的影响,之后人类活动占主导地位。     

Impedance Method for Abnormality Detection of a Branched Pipeline System

In this paper, an integrated detection scheme is developed to simultaneously address a leakage, a partial blockage and unknown branched pipeline elements. Expressions for the pressure head and discharge for a branched pipeline system having both a leakage and a blockage are derived in frequency domain. Boundary conditions for a reservoir and a branched dead-end allow the development of impedance formulations. The condition for a pipeline junction can be addressed using either a common condition for the pressure head combined with a continuity condition of discharge or a connectivity condition for impedance. In order to consider the unsteady friction’s impact, the impedance development process studied both the impact resulting from velocity profiles with two-dimensional distributions and the impact resulting from local and convective accelerations. Impedance expressions are derived for two distinct branched pipeline systems at different abnormality conditions. Based on drived formulations describing these systems, response functions were derived in the frequency domain and their corresponding time domain representations were integrated into a meta-heuristic calibration scheme for inverse transient analysis. Using an objective function for minimization of root-mean-square-errors between the observed and computed pressures, the calibration based one impulse response can simultaneously predict locations and magnitudes of abnormalities as well as parameters for a branched pipeline. The strength of the impedance-based approach for inverse transient analysis arises mainly from its feasibility to address different conservation conditions for pressure and discharge and for combining these conditions into a unified impedance connectivity condition.     

Identification of significant pressures and impacts upon receiving waters.

This study gives a review on the process of identification of significant pressures and impacts, which is an important part of river basin planning and in particular for implementing the EU Water Framework Directive (WFD) (2000/60/EC). The questions: what is a "significant pressure" in terms of the WFD? which sources and driving forces have to be regarded? which data can be used? which pressure on a water body is significant? and which implications and requirements result from the identification process?--should be considered. The European Commission requires reporting from all Member States about the status of the water bodies within a river basin district and about the risk of failing the environmental objectives by the end of 2004. Therefore, a number of prevailing projects across Europe aim to develop a guideline on a common understanding of the most effective approach towards the identification of significant anthropogenic pressures, and the analysis of potential impacts including the identification of appropriate tools and models. In such a guideline suitable and intelligent criteria have to be developed in order to enable a uniform assessment of the anthropogenic pressures within a river basin district.     

几种常见截面形式的水锤波速及其影响因素的分析

研究水电站引水系统的水锤现象。无论对引水道的设计还是运行都具有重要意义。前人对水锤波传播理论的研究推导出了圆形管道截面及方（矩）形薄壁管的波速表达式，但随着有压引水道多种截面型式的出现，这些表达式就远远不能满足要求。目前，对非圆形截面，一般都参照圆形截面的水锤波速，进行分析计算，这必然影响水锤压力及水力共振计算结果的准确性。因此，本文采用结构力学方法及有限元方法，绘制出一组波速曲线；并在分析各种影响因素的基础上，绘出了常见引水道截面型式的波速范围。     

近100多年来香港和澳门气温时序变化特征及其与ENSO的关联性

基于近 100 多年来的均一化气温数据,从趋势变化、季节差异、突变特征、周期振荡方面诊断香港和澳门的气温变化特征。结果表明: ( 1) 港澳年平均气温和不同季节气温在近 100 多年来均呈显著增加趋势,其中春冬季节增加速率较大,夏秋季节增加速率较小。除秋冬季节外,其它时间上的香港气温增加趋势均大于澳门。港澳夏冬季节气温差异均呈减少趋势。( 2) 香港和澳门年平均气温分别于 1963 年和 1991 年发生突变。在季节上,港澳地区的气温突变均在秋季发生年份最晚,冬季次之,夏季再次之,春季最早。( 3) 香港年平均气温分别存在 3 a、7 a、15 a 和 30 a、60 a 和 120 a 的周期振荡特征。澳门年平均气温存在 3 a、6 a、12 a、24 a 和 48 a 左右的周期振荡特征。( 4) ENSO 与香港年平均气温在 4 a 以下尺度以同位相或提前 1 a 位相变化关系为主,在 4 a 以上尺度以同位相变化关系为主。ENSO 与澳门年平均气温在不同时频域均以同位相变化关系为主。     

Sludge storage for countering nitrogen shock loads and toxicity incidents

Spare nitrification capacity is usually needed for a nitrifying activated sludge plant to counter nitrogen shock loads and/or toxicity incidents. The traditional way to provide this capacity is to apply a sludge retention time which is much longer than what needed to obtain a stable nitrification, resulting in over designed plants. Another approach, which is investigated in this paper, is to store the spare biomass in a separate sludge storage tank and return it to the main stream process when a shock nitrogen load or a toxicity incident occurs. Model based analysis reveals the unique feature of the scheme: different particulate components in the sludge have a different retention time, and more specifically, active biomass stays longer in the plant than inert solids. This results in that a plant with a storage tank can have the same amount of active biomass as a traditional plant but less sludge, opening the potential of reducing the volume of the plant. Analysis shows that a plant with a sludge storage tank can be about twenty percent smaller than a traditional plant that has the same treatment capability. Analysis is verified by simulation studies.