给水管网状态估计的优化方法

从给水管网运行工况的实时模拟角度出发 ,提出了管网状态估计的数学模型 ,并讨论了模型的解以及采用简约梯度法求解模型的关键步骤 ,用算例对模型进行了验证。仿真计算结果表明 ,该模型是正确可行的 ,采用的求解方法具有很好的稳定性和较快的收敛速度     

用广义简约梯度法求管网经济管径

本文针对提水灌溉管网设计中，管段流量分配对经济管径的影响，采用了非线性优化中的广义简约梯度法，构造了一个无需假定流量分配的管径优化设计算法。本文算例表明这一算法具有良好的收敛性，并且在管径优化的同时，作为从属状态的管段流量也达到了最佳的分配形式。该算法通过求解线性规划模型最终得出经济规格的管径，获得了较满意的效果。     

用广义简约梯度法求管网经济管径

本文针对提水灌溉管网设计中，管段流量分配对经济管径的影响，采用了非线性优化中的广义简约梯度法，构造了一个无需假定流量分配的管径优化设计算法．本文算例表明这一算法具有良好的收敛性，并且在管径优化的同时，作为从属状态的管段流量也达到了最佳的分配形式．该算法通过求解线性规划模型最终得出经济规格的管径，获得了较满意的效果     

自压式树状管网神经网络优化设计

应用Hopfield神经网络模型的优化计算原理与方法, 建立了自压式树状管网神经网络优化设计模型, 并用计算机软件模拟方法求解. 研究表明: 人工神经网络法是快速求解自压式树状管网非线性规划模型的一种新方法, 结合两级优化算法可以实现树状管网全局最优设计.     

Excel规划求解的环状给水管网平差

Excel规划求解环状给水管网平差,以管段流量为变量,各环闭合差的绝对值之和取得最小值为目标函数进行规划求解,通过设置节点连续性方程为约束条件,节点流量无需手工计算而自动平衡.采用Excel的公式与函数成批运算,便于选择管径取得经济流速,是一种环状给水管网优化设计和水力计算的新方法.同等环状给水管网的算例计算表明,与Hardy.Cross法相比,规划求解法过程简单快捷,求解精度高,4个环闭合差的绝对值之和为2.64×10-5(kPa)     

基于高维多目标优化的给水管网设计方法——以意大利Fossolo小镇管网为例

给水管网优化设计是一个多变量、非线性的多目标组合优化问题。对优化方案的选择会直接影响工程的投资。因此,在决策阶段有效平衡各个优化目标之间的内在关系,以实现综合效益最优尤为重要。基于高维多目标优化模型提出一种给水管网设计的新方法。首先,将多个工程设计需求作为模型中的优化目标,建立给水管网设计的高维多目标模型;然后,使用高维多目标进化算法Borg求解上述模型得到Pareto最优解;最后,利用双基点法(TOPSIS)对Pareto最优解进行排序得到综合效益最优的设计方案。基于意大利Fossolo小镇的管网设计问题,通过比较高维多目标模型与传统的多目标模型(仅考虑成本和管网系统可靠性指标)获得的最优方案,证明了基于高维多目标优化的设计方法能为决策阶段提供更多综合效益占优的备选方案,从而提高给水管网设计的合理性。     

河流水质灰色非线性规划的理论与应用

本文探讨了含灰参数的河流水质非线性规划理论与求解方法。通过引入灰数的概念，建立了描述河流水质模及规划中广义不确定性的灰凸集，灰凸规划的初步理论，然后，针对河流水质灰色非线性规划模型求解问题，提出了基于拓广了的Ｋｕｈｎ－Ｔｕｃｋｅｒ定理直接解法，其特点是将原灰色非线性规划模型分解成等价的两个确定性边界模型直接求解，这不仅为处理灰色水质规划提供了有效手段，而且建立了确定性规划与非确定性规划的联系，通过     

滨江山地城镇给水管网优化方法研究与工程实例

研究了滨江山地城镇给水管网的分区优化模型,得出了适用于研究对象的优化目标函数数学表达式,并进行分区优化。由于滨江山地城镇给水管网组成多而分散,管网结构复杂,相应的优化问题属于大型混合离散变量优化问题,模型最优解求解难度大。故提出分步分级优化思想的分层协调算法求解管网优化。首先将管网优化问题分解成管网分区布局优化和各区管网运行参数优化两个优化阶段,逐层寻优,从而求解管网最优化。根据某实例的优化结果可知,该模型及求解方法合理有效,可适用于滨江城镇管网优化。     

给水管网优化设计的新方法—广义简约梯度法

本文讨论了城市给水管网设计中管段流量分配对经济管径的影响,采用非线性优化中普遍认为是行之有效的广义简约梯度法(GRG)构造了一个无需假定流量分配的管径优化设计算法。本文算例表明这一算法具有良好的收敛性,并且在管径优化的同时,作为从属状态的管段流量也达到了最佳的分配形式。该算法通过求解线性规划模型最终绘出标准规格的管径。     

用遗传算法求解给水管网系统优化改扩建模型

针对给水管网系统所面临的改扩建问题 ,建立了给水管网系统实用优化改扩建模型。采用遗传算法求解 ,一次性解决了求解管径标准化的难题 ,同时计算得到水源最优分配流量。在不影响水力模型计算精度的前提下 ,引入管网简化 ,对非改扩建区域的管网实现任意程度的简化 ,大大提高了计算速度 ,并用实例进行了验证     

Model for real-time optimal flood control operation of a reservoir system

A methodology and model have been developed for the real-time optimal flood operation of river-reservoir systems. This methodology is based upon combining a nonlinear programming model with a flood-routing simulation model within an optimal control framework. The generalized reduced gradient code GRG2 is used to perform the nonlinear optimization and the simulator is the U.S. National Wheather Service DWOPER code. Application of the model is illustrated through a case study of Lake Travis on the Lower Colorado River in Texas.     

INVESTIGATION OF THE FLOW IN FRACTAL RESERVOIR INCLUDING THE EFFECTS OF QUADRATIC GRADIENT TERM

According to the assumption of slightly compressible fluid, the quadratic gradient term in the nonlinear partial differential equations for the traditional well-test model is usually neglected. The linear partial differential equation is thus established. It is known that neglecting the quadratic gradient term results in errors for long-time well tests. A nonlinear flow model for fractal medium is constructed and the quadratic gradient term is considered. The exact solutions of the fractal reservoir models are obtained by Laplace transform and Weber transform in a constant-rate and constant-pressure production for an infinitely large system. This paper addresses the variation of pressure with fluid compressibility coefficient and fractal reservoir parameters. The plots of the typical pressure curves are constructed, and the results can be applied to well-test analysis.     

The influence of nonlinear shear stress on partially averaged Navier-Stokes(PANS) method

In most of partially averaged Navier-Stokes(PANS)methods,the Reynolds stress is solved by a linear hypothesis isotropic model.They could not capture all kinds of vortexes in tubomachineries.In this paper,a PANS model is modified from the RNG k-?turbulence model and is used to investigate the influence of the nonlinear shear stress on the simulation of the high pressure gradient flows and the large curvature flows.Comparisons are made between the result obtained by using the PANS model modified from the RNG k-?model and that obtained by using the nonlinear PANS methods.The flow past a curved rectangular duct is calculated by using the PANS methods.The obtained nonlinear shear stress agrees well with the experimental results,especially in the high pressure gradient region.The calculation results show that the nonlinear PANS methods are more reliable than the linear PANS methods for the high pressure gradient flows,the large curvature flows,and they can be used to capture complex vortexes in a turbomachinary.     

各种扰动源产生孤立子波的研究

本文就四种不同形式的扰动在浅水中生成孤立子波的问题进行了研究。这里采用的理论基础是Boussinesq型非线性色散长波模型。非线性偏微分方程组按初-边值问题用有限差分法数值求解,这里包括对开边界条件的近似处理。 数值计算实例给出了四种不同扰动源生成孤立子波的条件和规律。由对计算结果的分析比较,可以发现当外界与流体间有一定方式的质量、动量或能量(动能、位能)交换时,只要满足一定的条件均能生成孤立子波。     

供水管网水力计算与优化调度

本文用图论理论和稀疏矩阵技术进行城市供水非线性管网的水力分析，以减少存贮量和计算时间，对仅有泵站水源的管网，用两级递阶优化法进行优化调度，用正交试验法解决一般管网改建或扩建问题，计算机仿真结果表明，管网系统优化调度有效好的效果效益。     

水布垭面板堆石坝渗流场分析和分区材料允许比降设计指标研究

 采用饱和非饱和非稳定渗流模型对水布垭面板堆石坝在正常运行、面板局部缺损和面板失效等工况下的渗流场进行了较全面的模拟计算,分析了大坝各分区的水头和比降的分布,确定了垫层、过渡区和主堆石区可能出现的最大比降。这种最大比降对坝体渗透稳定性具有控制意义。据此提出了分区材料允许比降设计指标的建议值,为评价面板堆石坝分区之间水力过渡合理性和渗透稳定性提供了依据。     

改进的广义Bingham岩石蠕变模型

基于岩石全自动流变伺服仪上得到的绿片岩三轴流变试验数据，分析蠕变曲线的特征，构造出能够表现岩石衰减蠕变和加速蠕变阶段特征的非线性函数，引入到广义Bingham的蠕变本构方程中，得到一个新的非线性蠕变模型，该模型的材料参数较少。通过绿片岩流变数据对新的非线性蠕变模型的参数进行辩识，得到了蠕变模型的材料参数。对蠕变模型计算结果和试验结果的比较表明，该模型能够很好的描述蠕变曲线中的初始衰减蠕变阶段、稳态蠕变阶段和加速蠕变阶段，证明了该模型的正确性和合理性。     

考虑相速弥散影响的单频波变形数学模型

本文提出了逼近Hedges(1987)的考虑位相弥散影响的非线性弥散关系的显式表达式，该显式表达式与Hedges的非线性弥散关系吻合较好。用文中显式非线性弥散关系，结合含弱非线性效应的缓坡方程，得到考虑相速弥散影响的单频波变形数学模型。对该数学模型进行了数值验证，验证结果表明，考虑相速弥散影响的单频波变形数学模型更为精确、合理。     

BOUSSINESQ MODELLING OF NEARSHORE WAVES UNDER BODY FITTED COORDINATE

A set of nonlinear Boussinesq equations with fully nonlinearity property is solved numerically in generalized coordinates,to develop a Boussinesq-type wave model in dealing with irregular computation boundaries in complex nearshore regions and to facilitate the grid refinements in simulations.The governing equations expressed in contravariant components of velocity vectors under curvilinear coordinates are derived and a high order finite difference scheme on a staggered grid is employed for the numerical implementation.The developed model is used to simulate nearshore wave propagations under curvilinear coordinates,the numerical results are compared against analytical or experimental data with a good agreement.     

Seepage simulation of high concrete-faced rockfill dams based on generalized equivalent continuum model

This research focused on the three-dimensional (3D) seepage field simulation of a high concrete-faced rockfill dam (CFRD) under complex hydraulic conditions. A generalized equivalent continuum model of fractured rock mass was used for equivalent continuous seepage field analysis based on the improved node virtual flow method. Using a high CFRD as an example, the generalized equivalent continuum range was determined, and a finite element model was established based on the terrain and geological conditions, as well as structural face characteristics of the dam area. The equivalent seepage coefficients of different material zones or positions in the dam foundation were calculated with the Snow model or inverse analysis. Then, the 3D seepage field in the dam area was calculated under the normal water storage conditions, and the corresponding water head distribution, seepage flow, seepage gradient, and seepage characteristics in the dam area were analyzed. The results show that the generalized equivalent continuum model can effectively simulate overall seepage patterns of the CFRD under complex hydraulic conditions and provide a reference for seepage analysis of similar CFRDs.