基于在线学习的水轮发电机组智能控制系统研究

针对水轮机调节系统非线性、结构参数变化范围较大的特点，提出了一种能够在线学习的智 能控制系统。它以模糊神经网络为学习器，以模糊推理和智能处理机构为控制器，将两者结 合起来共同完成水轮发电机组的调节任务，并详细讨论了学习器的建立和学习方法及智能控 制系统的运行方式。仿真研究表明，其有较强的学习能力、良好的实时控制性能，能适应水 轮机调节系统结构、参数变化较大情况下的控制要求。     

水轮机调节系统自适应滑模控制策略

水轮机系统惯性参数是影响水轮机调节系统动态特性的重要参数，传统控制方法大都是基于水轮机及其引水系统近似简化模型，很难改善水轮机调节系统动态特性。应用径向基函数神经网络逼近水轮机及其引水系统非线性特性，利用李雅普诺夫稳定性理论设计并证明水轮机系统惯性参数自适应估计律，设计了一种基于水轮机系统非线性特性和惯性参数估计的滑模鲁棒控制器，并完成仿真实验。仿真结果表明，该滑模鲁棒控制水轮机调节系统具有较高的跟踪精度、控制器输出抖振较小等优点，为水轮机调节系统高精度转速跟踪提供有效参考。     

基于遗传算法的水轮机模糊自适应PID调节系统控制规则

针对水轮机调节系统常规PID控制参数不能根据系统的动态过程自动调整控制参数的问题，结合遗传算法与模糊PID控制，用遗传算法优化模糊自适应PID控制的模糊规则，利用模糊推理的方法求解PID参数的变化量，对PID参数进行自动整定。同时针对遗传算法寻优生成的模糊规则存在跳变和规则曲面粗糙等缺陷，在目标函数中引入光滑因子，有效解决了模糊规则跳变现象。仿真表明，该方法是寻找水轮机调节系统模糊自适应PID控制规则的一种可行方法。     

水轮机调节系统控制策略综述

综述水轮机调节系统常规PID控制、自适应控制、智能控制和非线性控制的特点,指出模糊控制和专家控制精度较低;神经元网络控制学习速度较慢、易收敛到局部最小点;遗传算法可有效地解决参数寻优问题;非线性控制着眼于水轮机调节系统的非线性特性,控制效果较好.提出将非线性控制与其它控制策略相结合形成复合控制,将是水轮机调节系统控制策略的发展方向.     

调节对象参数和运动特性随工况变化的分析

水轮机调节对象的许多参数都是随运行工况变化的。以调节对象线性化模型为基础，从1个实例计算人手，计算了不同工况下水轮机传递系数和发电机6个参数的变化情况，进而计算这些参数变化对捌节对象特征根的影响。通过汁算表明，其水力振荡衰减速度与出力有关．而系统的其他运动特性随工况变化较小。     

在水轮机调节系统动力学分析中描述水轮机特性的一种新方法

一、问题的提出利用电子计算机分析水轮机调节系统动力学特性,通常用数据表格插值法确定水轮机特性参数。引水系统中的水击现象是水轮机调节系统的重要特性,它的本质是一个反向微分环节,构成力矩反抛现象。这表明在调节过程的起始阶段力矩变化与调节目的相反。     

智能控制技术在水轮机调节系统中的应用

概述了水轮机调节系统的特点以及智能控制技术的发展历史与现状，着重介绍了智能控制中模糊控制、神经网络控制、专家控制、遗传算法等的特点及在水轮机调节系统中的应用情况，并提出智能控制技术作为水轮机调节系统的一种新型控制技术必然朝着综合化、集成化方向发展。     

基于Matlab/Simulink的水轮机调节仿真研究

针对物理模型建造、参数改变困难的情况,在Matlab/Simulink工具箱下建立了水轮机调节系统仿真模型。考虑到水轮机特性的非线性和引水管道长的特点,水轮机模型采用了非线性模型、引水系统采用了弹性水击模型,仿真计算结果与实测结果吻合得很好。通过仿真模拟各种工况下水轮机的运行,有助于了解水轮机调节系统实际运行中的变化情况。对Simulink下的水轮机调节系统的数学模型、仿真实验结果与实测值的对比分析作了简要介绍。     

BP网络模糊PID控制在水轮机调速器中的应用

为了改善水轮发电机组的动态调节品质,对神经网络控制在水轮机调节中的应用进行理论分析,将基于BP神经网络的模糊PID控制器应用于水轮机调速系统.仿真和实验结果表明,该控制器具有良好的调节品质,其控制作用对改善水电机组的动静态特性和对参数时变的适应能力等方面均优于常规PID调节器,为神经网络控制在水轮机调节系统中的应用打下了良好的理论基础.     

水轮机调节系统的MATLAB仿真模型

介绍了水轮机调节系统建模及其分析方法.仿真模型是基于MATLAB Simulink建立的,能实现水轮机调节系统空载运行、甩100%额定负荷、接力器不动时间、孤立电网运行和一次调频等动态过程的仿真.仿真结果有助于加深对水轮机调节系统基本原理的理解,也有助于了解被控制系统参数(调节对象)和水轮机控制系统(调速器)参数对水轮机调节系统动态特性的影响.     

Call for Papers

正As the eldest and most distributed professional journal of water industry,Water Wastewater Engineering(W WE)gained very wide acceptance from the colleagues working in this field in this country since start publication in 1964.Now it is administrated by the Ministry of Construction of the People’s Republic of China and sponsored by the China Civil Engineering Society etc.     

SPATIAL AND TEMPORAL WATER QUALITY VARIABILITY IN AQUATIC HABITATS OF A CULTIVATED FLOODPLAIN

The floodplains of lowland rivers contain diverse aquatic habitats that provide valuable ecosystem services but are perturbed when intensively cultivated. Hydrologic, water chemistry and biological (fish) conditions in five aquatic habitats along the Coldwater River, Mississippi, were measured for more than 4 years: the river, two severed meanders that functioned as backwaters, a managed wetland and an ephemeral channel draining cultivated fields. Off‐channel habitats were connected to downstream regions 0.10% to 32% of the dry season and 24% to 67% of the wet season. The median temperatures for the five monitored sites ranged from 18°C to 23°C, the median total solids concentration for all sites was 135 mg L^?1, the median total phosphorus was 0.29 mg L^?1 and the median total nitrogen was 1.56 mg L^?1. Chemical and physical water quality displayed strong seasonal differences between the wet winter/spring and the dry summer/fall periods so that temporal variation consisted of gradual seasonal trends superimposed on strong diurnal variations. All off‐channel habitats exhibited periods of hypoxia and temperatures >30°C during the dry season. Between‐site gradients of water and habitat quality were strongly coupled to water depth and runoff loading. The rehabilitation of one backwater by increasing water depth and diverting agricultural runoff was associated with improved water quality and fish species richness relative to an adjacent untreated backwater. The diversion of polluted runoff and the use of water control structures to maintain greater water depth were observed to be effective management tools, but the former reduces the water supply to habitats that tend to dry up and the latter reduces connectivity. Published in 2011 by John Wiley & Sons, Ltd.     

Spatio‐temporal variation of gross CO2 and CH4 diffusive emissions from Australian reservoirs and natural aquatic ecosystems,and estimation of net reservoir emissions

Carbon dioxide (CO₂) and methane (CH₄) diffusive emissions were measured during two field surveys in Queensland and Tasmania, Australia, using the floating chamber method. Bubbling and degassing emissions in 2010 were estimated in Koombooloomba Dam reservoir using only inverted funnels and gas concentrations, respectively. A total of 14 reservoirs and 16 rivers and lakes were sampled from 2006 to 2010. Spatial variation was substantial within each water body, as well as between them. The main drivers of diffusive emission variation were physiographic region and climate, with a clear demarcation being observed between diffusive emissions from tropical Queensland and temperate Tasmania, and between the humid West Coast Range (Tasmania) and dry Central Plateau (Tasmania). Higher CO₂ and CH₄ diffusive emissions were observed during the dry season, when long water residence times would promote organic matter degradation. Estimated total gross emissions, including diffusive, bubbling and degassing emissions, for Koombooloomba Dam reservoir were about 1.5 × 10⁶ t CO₂eq km² per year, or 24 × 10⁶ t CO₂eq per year. This corresponds to a plant emission factor of 3.18 kg CO₂eq MWh^?1. Using an estimate of terrestrial emissions derived from literature data for the Tully River catchment area, rough estimated net emissions from the catchment area are about 44 kt CO₂eq per year, or 5.83 kg CO₂eq MWh^?1, which is in the lower range of the studied reservoirs.     

库水波动下库岸边坡地下水浸润线解析解及误差分析

解析法是库岸边坡地下水浸润线计算中便于实际应用的方法,但该方法须基于若干假定并对潜水运动基本方程线性化后才能求解。针对各假定和线性化过程建立不同的地下水渗流数学模型,用解析法和有限元法解答上述数学模型,分析各误差大小及其规律。结果表明：库岸垂直处理带来的误差要小于方程线性化处理和不考虑非饱和渗流带来的误差,而且它们都随渗透系数变大而减小;在三峡库区库水调度情况下,假定库水位等速变化带来的误差对大多岸坡而言可以忽略;计算库岸边坡地下水浸润线时,解析法只适用于水位变化幅度相比含水层厚度较小,且几何边界规则、岩土结构简单、岩土体渗透性较好时的情况。     

Changes in Summer Irrigated Crop Area and Water Use in Southeastern Turkey from 1993 to 2002: Implications for Current and Future Water Resources

Changes in summer irrigated cropland acreage and related water use are estimated from satellite remote sensing and ancillary data in semi-arid Southeastern Turkey where traditionally dry agricultural lands are being rapidly transformed into irrigated fields with the help of water from the Euphrates-Tigris Rivers. An image classification methodology based on thresholding of Landsat NDVI images from the peak summer period reveals that the total area of summer irrigated crops has increased three-fold (from 35,000 ha to over 100,000) in the Harran Plain between 1993 and 2002. Coupled analysis of annual irrigated crop area from remote sensing and potential evapotranspiration based estimates of irrigation water requirements for cotton indicate a corresponding increase in agricultural water use from about 370 million cubic meters to over one billion cubic meters, a volume in accordance with the state estimates. These estimates have important implications for understanding the rapid changes in current agricultural withdrawals in Southeastern Turkey and form a quantitative basis for exploring the changes in future water demands in the region. For example, expansion of irrigated lands have led to a steady decrease in potential evaporation due to increased roughness and decreased humidity deficit in the Harran Plain. Assuming that the changes in future evaporation conditions will be of similar nature, water use for irrigation is expected to decrease over 40 percent in future irrigation sites. Incorporating this decrease in overall planning of the irrigation projects currently under construction should lead to improved management, and by extension, sustainability of water resources in the region.     

Serial discontinuities in a Rocky mountain river. II. Distribution and abundance of trichoptera

River regulation in the headwaters and middle reaches of the Gunnison River, Colorado, significantly altered distributions and abundances of Trichoptera fauna. Twenty-five species were collected from mainstream samples, with the greatest species richness occurring at an unregulated, rhithron segment above the central reach dams. At sites immediately below the three hypolimnial-release dams and a reregulation dam, species richness was reduced 35–90 per cent and abundance > 95 per cent. Net-spinning caddisflies were the dominant trichopterans at unregulated sites; Arctopsyche grandis in the upper reaches (218 organisms, 586 mg dry mass m^?2) and Hydropsyche cockerelli, H. occidentalis and Cheumatopsyche pettiti in the lower river (9041 total organisms, 6621 mg m^?2), downstream from the last dam. The observed distributional pattern of low trichopteran densities in dam tailwaters and high hydropsychid densities at sites 60–80 km below the central reach dams is a classic expression of continuum resets and adjustments in response to stream regulation as predicted by the Serial Discontinuity Concept.     

Surveying for Water Resources

Abstract

A professional Land Surveyor (Geomatician) describes the Hydrogeologists' survey requirements of a major water resources assessment for the government of The Sultanate of Oman (1992 to 1996). The need for objective specifications is stated. Specialist terms like geoid, spheroid, Mean Sea Level are explained and how to relate spheroidal levels to the geoid. Methods like traditional survey, satellite survey, and photogrammetry are introduced. The paper encourages coordinated working for the benefit of water resource assessment and recommends employment of the professional land surveyor for major studies.     

浅谈优化Vray渲染在制作三维场景的应用研究

用Vray三维渲染引擎来渲染三维场景,其质量和速度是由一些影响因素和参数设置决定的,不同的参数和因素,可以得出不同的三维渲染效果.因此,分析、优化三维渲染质量和速度的影响因素,正确、合理的选择参数对提高Vray最后渲染阶段的质量和速度非常重要.     

固结、渗流和沉积控制方程研究

本文从两相流体动力学的守恒方程出发，考虑固相、液相的相对运动，推导了可以考虑场的不均匀性和流体压缩性的统一形式的控制方程，并对方程所基于的物理概念和相互联系进行了必要的分析。通过对方程适当形式的表达，可导出用于大、小变形固结、渗流和沉积的简化方程，显示了在不同领域的三个理论存在一定的统一性。方程推导过程并未对本构关系加以限制，适用范围较广。依据实际问题的要求，作了不同形式的简化。     

四川省及重庆市中型水电站效益分析

该文分析了四川省及重庆市几座中型水电站的调查材料表明：四川省及重庆市中型水电站不仅在川渝主网和地方电网中起着很大的作用，并具有巨大的社会效益，同时还有综合利用效益，说明修建中型水电站的优越性．