Sensor Placement Strategy for Pipeline Condition Assessment Using Inverse Transient Analysis

Water Resources Management - Inverse transient analysis (ITA) has been recognized as a useful technique for pipeline condition assessment, such as leak detection and pipe wall thickness estimation....     

Optimal Localization of Pressure Reducing Valves in Water Distribution Systems by a Reformulation Approach

Leakage reduction represents one of the most challenging tasks in managing water distribution systems (WDSs). An effective way to leakage reduction is to carry out network operational pressure management through optimizing locations and regulations for pressure reducing valves (PRVs) and system pressures. This leads to a mixed-integer nonlinear program (MINLP) with a large number of binary variables which make it difficult to solve by an available software package. In this study, instead of directly solving the MINLP problem, we reformulate it to a mathematical program with complementarity constraints which can be efficiently solved by available NLP algorithms. The binary variables are replaced by continuous ones with complementarity constraints to be satisfied by a penalization scheme. To improve the quality of the solution and also to accelerate the convergence, in each relaxed NLP the results of the binary variables are rounded to binary values with which the NLP problem is solved again to achieve a MINLP solution. The final solution will be determined by the best one among the MINLP solutions. The results from two case studies reveal new and better combinations of PRVs as compared with those given in the literature.     

基于多尺度卷积神经网络的管道泄漏检测模型研究

如何有效检测管道泄漏是节水型社会建设迫切需要解决的关键和热点问题之一。近年来基于深度学习的管道泄漏检测方法发展迅速,本文针对传统单尺度卷积神经网络对泄漏特征提取不充分的问题,提出一种基于多尺度一维卷积神经网络(MS1DCNN)的管道系统泄漏检测模型。该方法利用多个不同卷积尺度的卷积通路并行提取管道泄漏的特征并进行泄漏信息的分类预测。基于经典的管道系统布置,利用瞬变流模型生成管道泄漏工况下的三个水压数据集对模型进行验证,三个数据集分别用于预测管道的泄漏位置、泄漏量和非恒定摩阻系数,对应样本数为39601、3980、4900,并将预测结果与其他深度学习方法和传统的机器学习方法进行对比分析。结果表明：MS1DCNN模型对数据集样本下泄漏位置、泄漏量、非恒定摩阻系数的分类准确率达到99.96%、98.48%、100%,三者平均预测精度比传统一维卷积神经网络(1DCNN)、BP神经网络、支持向量机(SVM)和k近邻算法(KNN)提高0.31%、2%、1.27%、22.8%;MS1DCNN在信噪比为-4～12 dB的噪声环境下各数据集的平均F₁分数分别为99.2%、97.02...     

管道系统泄漏检测的全频域法

针对长距离管道输水系统的特点,建立了适合各种边界条件的管道水击频域数学模型,并应用拉氏变换原理导出了实测离散函数的频域数学模型。在此基础上,提出完全在频域中检测管道泄漏的新方法,即管道泄漏检测的全频域法。全频域法与之前频域法的差别有两点:一是边界条件不受限制,二是泄漏检测完全在频域中完成,无需求解任何一点的傅里叶逆变换时域函数。最后通过数字算例检验了管道泄漏检测全频域法的可行性。     

应用非参数的MK和ITA方法分析地下水水质参数变化特征——以新三矿含水层为例

矿区地下水水质变化是影响矿区生态环境和矿井安全生产的制约因素之一,正确认识水质变化趋势是首要任务。根据以往实测水质参数pH、COD、Na~++K~+、Ca~(2+)、Mg~(2+)、Cl~-、SO_4~(2-)和HCO_3~-的数据,采用Mann-Kendall检验法(MK)和Innovative Trend Analysis(ITA)探讨新三矿由上而下6个不同含水层水质参数随时间的演变规律,并且针对不同的数值变化范围选用不同的ITA指数。通过比较,两种方法结果有很好的一致性,结论认为:相比MK检测法,定量的ITA法拥有更多的优点,可以图形化地表示分析结果,可以通过将水质参数值分为低、中、高水平更好地分析水质参数的趋势和次要趋势;8种水质参数中,Ca~(2+)和Mg~(2+)相较其他离子能表现出更显著的变化趋势;6种含水层中,大青灰岩含水层中Cl~-浓度的低、中值下降而高值上升,煤层顶板山西组砂岩含水层和底板奥陶系灰岩含水层大部分水质参数显著下降,矿化度逐渐降低。     

Trend Analysis of Maximum Hydrologic Drought Variables Using Mann–Kendall and Şen's Innovative Trend Method

Droughts as destructive climatic extreme events affect natural environment of an area. Identifying droughts has a vital importance in the planning and management of water resource systems of a river basin. This study investigates the trends of maximum hydrologic drought variables, annual maximum duration (AMD), and annual maximum severity (AMS), by using Mann–Kendall, modified Mann–Kendall, and recently developed ?en's innovative trend analysis (ITA) methods. These methods are applied to the AMD and AMS of nine different stations located in Coruh River Basin, Turkey, in which numerous highly critical power plants have recently been constructed, under construction, or planned. Basic Mann–Kendall test indicated no trend in the investigated stations while the modified Mann–Kendall gave significantly decreasing trend for AMS series of station 2304 and for AMD series of station 2321 at 10% significance level. Modified Mann–Kendall and ITA approaches indicate that the AMS of station 2304 show significantly decreasing trend. According to the ITA method, the peak AMS values of the stations 2315 and 2322 have also significantly decreasing trend after 1986. Both modified MK and ITA methods provide increasing trends in drought severities of the stations 2316 and 2323. It should be noted that some droughts or water stress may be occurred in these stations in the future. Modified Mann–Kendall test provides no significant trend for the seven stations while ITA results indicated some positive or negative trends at these stations. The primary points of interest of ?en's ITA method are that it is not subject to any assumption such as serial relationship, non‐normality, sample size, and trends of low, medium, and high data can be seen by this method easily. The study indicates that the ITA method could be simply and successfully used by hydrologist or water resources decision makers or in identifying droughts to prepare efficient management plans. Copyright © 2016 John Wiley & Sons, Ltd.     

混凝土面板坝ITA固坡技术试验与施工技术

ITA固坡技术目前在国内已广泛采用,通过对ITA固坡施工技术及盘石头水库ITA固坡技术的试验研究成果的分析,阐述了ITA固坡技术的原理、优点、施工方法.     

ANALYSIS OF FIRST TRANSIENT PRESSURE OSCILLATION FOR LEAK DETECTION IN A SINGLE PIPELINE

The leak detection is of great importance in the reliable operation and management of a pipeline system. Recently,attention is shifted to the use of the time domain or frequency domain methods based on the transient analysis. These methodssometimes require accurate pressure signals obtained during the transient period or by creating ideal conditions in testing. This paperproposes a method that does not require transient simulations over the whole or an extended period of time, but uses the first transientpressure oscillation to detect leaks. The method considers the propagation of the pressure oscillation wave created from a fast valveclosure and the reflected damp wave from the leak. A leak in the pipe gives rise to reflected waves which in turn creatediscontinuities in the observed signal at the measurement section. The timing of the reflected damp wave and the magnituderepresent the location and the size of the leak, respectively. An analytical expression is derived based on the Method OfCharacteristic (MOC) for the relationship between the leakage and the reflected magnitude. The leak detection procedure based onthe method is also given. Then the reliability of the method is tested on numerically simulated pressure signals and experimentalpressure signals with calibrated leak parameters, and the results indicate a successful application and the promising features of themethod.     

BP 网络日径流序列预测的NLP 适用条件研究

对非线性预处理在人工神经网络日径流预测中的适应过程进行了仿真和模拟．提出了非线性预处理（NLP）适用条件的解算思路，通过实测数据和模拟数据，研究了NLP的适用条件。推导出NLP在神经网络SISO系统中适合于日径流预测，不适用于周平均流量序列、旬平均流量序列和月平均流量序列的预测，提出了判断NLP神经网络SISO系统进行日径流预测的有效性标准——多年日径流拐点14百分位．并通过广西平乐水文站和四川宝珠寺水文站1973～2001年的日径流量进行对比预测，验证了该标准是合理的。     

A Multiscale Approach to Leak Detection and Localization in Water Pipeline Network

Leak detection and localization in water pipeline networks is of paramount importance to industry, especially in regions where water is scarce. In this paper, we present a novel multi-modal and multi-scale approach for leak detection and localization in water pipeline networks, in which pressure measurements at various points on the network are used to localize the pipe segment in which the leak is occurring, and then the vibration sensors are used to localize the leak within this segment. In some situations where the complete pipeline model is not available, pressure data alone may not be effective in localizing the leak. However, in such a situation, by supplementing pressure data with vibration data, the leak can be localized, as these additional data are easier to acquire at arbitrary points, since vibration sensors are non-invasive. In order to validate the effectiveness of the approach that needs both pressure and vibration data, we simulate the pipeline model using EPANET that includes models for flow and pressure at various points on the pipeline, then integrate the vibration model with it in MATLAB, since EPNAET does not include models for vibration measurements. A case study of a pipeline network is considered, and the proposed scheme is used to detect and localize the leak. Extensive simulation results show the effectiveness of the proposed scheme in providing accurate leak detection and localization.     

考虑土拱效应的挡土墙被动土压力分析

基于库伦土压力理论,假定被动极限状态下挡土墙后大主应力拱迹线为抛物线,考虑土拱效应,推导了被动土压力系数的理论公式,并将其用于水平微分单元法,分析土体处于被动极限平衡状态时的应力状态,得到平动模式下被动土压力强度、合力及合力作用点的计算公式;在此基础上,分析了内摩擦角及墙面摩擦角对被动土压力系数、土压力强度及合力作用点的影响,并与库伦土压力理论等已有方法和模型试验数据进行了对比分析,验证了该计算方法的合理性。     

挡土墙背摩擦角为负的被动土压力研究

目前大多数被动土压力问题研究的是挡土墙背摩擦角为正的情况(墙身相对土体向下移动)，而挡土墙背摩擦角为负(墙身相对土体向上移动)的被动土压力问题则研究的较少。在平面滑裂面假设的基础上，利用散粒体Kötter方程通过极限平衡分析得到了挡土墙背摩擦角为负时的被动土压力系数、被动土压力合力和被动土压力合力作用点高度的理论公式。分析了挡土墙倾角、填土内摩擦角、填土坡角和墙背摩擦角对被动土压力系数、土压力合力作用点高度的影响。与挡土墙背摩擦角为正不同的是，墙背摩擦角为负时随摩擦角的增加，被动土压力系数减小。用图形和表格的形式给出了相应的结果，可为锚、输电线路基础受上拔荷载时设计所采用。     

Leak Detection in a Branched System by Inverse Transient Analysis with the Admittance Matrix Method

The diagnosis of water distribution systems by means of the inverse transient analysis requires efficient and reliable numerical models. In the network admittance matrix method (NAMM) the 1-D waterhammer governing equations are integrated in the frequency domain and organized in a laplacian matrix form. The NAMM is particularly suitable for complex systems because of this structure and can be used for the system diagnosis, including leak sizing and location. In this paper a damaged branched system is considered and the diagnosis is performed by means of the NAMM using experimental data from laboratory transient tests. Two different boundary conditions are used in the implementation of the NAMM and the leak is located and sized with a reasonable approximation. An extended numerical investigation is also presented and allows confirmation of the results for different leak locations. The use of the NAMM for the leak detection and the validation using experimental data on a branched system are the main original contributions of this work. The successful diagnosis indicates promising results for applications in more complex systems.     

掺气减蚀设施后二维空腔流动计算

本文发展了文献[4]中提出的求解自由面重力流的h2类边值问题理论。运用解析函数的Riemann-Hilbert混合边值问题的h3类边值问题理论，导出了计算有重力作用情况下双自由表面二维空腔势流流动的边界程分方程，提出了确定空腔区水舌下自由表面的计算格式，并在物理平面上进行了数值求解。表明，该数值方法具有收敛速度快、边界适应能力强、计算量小、计算精度高和对初值要求不高等特点。计算结果与实测资料对比分析表明，来流佛氏数Fr<7情况下，无需考虑阻力影响，采用势流模型即可获得与实测值相符合的结果；而在来流佛氏数Fr>7情况下，由于射流掺气加剧，需引入阻力修正。     

输水管道泄漏的探地雷达检测原理和现象机理分析

基于探地雷达检测输水管道泄漏是近年发展起来的一种很有前景、实用性很高的无损检测技术,国内在这方面的研究处于起步阶段,尚缺乏仪器设备研发和对漏水的现象、机理与反馈图像的比对研究。本文搭建了输水管道漏损雷达检测试验平台,开展了输水钢管漏水试验和检测试验,对比研究了无泄漏、有泄漏以及泄漏后、泄漏时等工况下典型测线雷达回波图像的异同,并反演了漏水工况的泄漏范围。结果表明:当管道泄漏后,泄漏水引起管道周围土壤介电常数显著变化,湿沙状态下平行管道测线雷达回波下移,呈明显的"V"型,垂直方向测线的回波双曲线形态更加陡峭,斜率更大,该畸变规律有利于锁定大致泄漏范围。"箭形回波"和"孔下回波"是区分管道泄漏时和泄漏后的雷达回波关键典型特征,尤其较为清晰的孔下回波亮斑是正在发生小泄漏的典型回波图像特征,且具有规律性。对于管道不停水泄漏的检测,如能辨识出箭形回波和孔下回波,即可实现泄漏的快速定位。试验验证了利用探地雷达检测输水管道泄漏的有效性,并为漏损探地雷达检测设备和软件的研发提供支撑。     

Optimal Long-term Operation of Reservoir-river Systems under Hydrologic Uncertainties: Application of Interval Programming

Long-term basin-wide reservoir-river operation optimization problems are usually complex and nonlinear especially when the water quality issues and hydrologic uncertainties are incorporated. It is due to non-convex functions in water quality modeling and a large number of computational iterations required by most of stochastic programming methods. The computational burden of uncertainty modeling can be reduced by a special combination of uncertainty modeling and interval programming, though the problem solution is still a challenge due to model nonlinearity. In this paper, an integrated water quantity-quality model is developed for optimal water allocation at river-basin scale. It considers water supply and quality targets as well as hydrologic, water quality and water demand uncertainties within the nonlinear interval programming (NIP) framework to minimize the slacks in water supply and quality targets during a long-term planning horizon. A fast iterative linear programming (ILP) method is developed to convert the NIP into a linear interval programming (LIP). The ILP resolves two challenges in NIP, first converting the large non-linear programming (NLP) into a linear programming (LP) with minimum approximation and second reducing the iterations needed in interval programming for NLP into just two iterations for the upper and lower limits of decision variables. This modeling approach is applied to the Zayandehrood river basin in Iran that has serious water supply and pollution problems. The results show that in this river basin at dry conditions when available surface water resources are below 85 % of normal hydrologic state and water demands are 115 % of current water demands, the total dissolved solids (TDS) concentration can be reduced by 50 % at the inlet of the Gavkhuni wetland located downstream of the river basin.     

管道泄漏检测的水力瞬变全频域数学模型

输水管道泄漏孔的存在及其位置直接影响着系统压力波形的畸变和衰减特性,通过分析有、无泄漏时任意位置处的压头频域特性可使泄漏检测成为可能.在考虑非恒定摩阻影响的基础上,提出基于水力瞬变全频域数学模型的泄漏检测反问题分析方法.用拉氏频域变换处理边界条件和实测数据,并将遗传算法用于频域反问题模型的求解,在寻优速度上比传统的瞬变时域分析的方法有了较大的改善.算例表明基于水力瞬变全频域数学模型分析的管道泄漏检测是一种有效的新方法.     

Leak Size,Detectability and Test Conditions in Pressurized Pipe Systems

The relationships between leak geometry and detectability are explored with a distinction between steady- and unsteady-state based techniques. Various criteria to evaluate the size and detectability of a leak are first discussed. These criteria can be useful for the benchmarking and the comparison of different techniques. Since the test conditions play a crucial rule in leak detectability, the proposed criteria take this effect into account. Furthermore, they show that while in steady-state conditions increases in system pressure enhance leak detectability, in transient state, by contrast, higher pressures tend to decrease detectability. This effect is also confirmed by experimental tests carried out at the Water Engineering Laboratory of the University of Perugia.     

波浪作用下砂质海床瞬时孔压特性的FLAC模拟

针对波浪荷载作用下砂质海床瞬时孔压响应问题,结合波流水槽模型试验实测结果,运用FLAC程序建立相应的流-固耦合本构模型,通过FISH函数使数值模型中的波浪加载与线性波理论相一致.并将数值模拟结果绘制成图和实测值进行比较分析,这是对FLAC渗流模块运用的拓展,以此进一步说明 FLAC有较好的模拟波浪加载下海床孔压特性的能力.     

热力管网泄漏检测数学模型

本文研究了基于恒定流动模拟的静态泄漏检测方法和基于水力瞬变模拟的瞬变泄漏检测法，分析了瞬变泄漏检测法用于热力管网的可行性，建立了瞬态泄漏检测法的数学模型，误差准则，以及泄漏位置的确定方法，并通过实际供热管网泄漏检测数值仿真作了比较，表明用瞬态泄漏检测法可显著改善热网微机监控系统泄漏检测的能力。