基于SOA的水轮机调速系统PID参数优化

针对现有优化方法复杂、易陷入局部最优等问题,为水轮机调速系统提出了一种基于人群搜索算法的比例-积分-微分控制参数优化方法.为验证该算法的可行性,建立了水轮机调速系统非线性模型,选取水轮发电机组转速偏差的积分时间绝对误差指标作为目标函数进行优化.为验证优化结果的有效性,将人群搜索算法的控制效果与参考文献中粒子群算法的控制...     

基于改进混合遗传算法的微型水轮机电子调速器的优化设计

针对微型水电站中水轮机组频率波动较大且运行不稳的问题,本文采用了一种单纯形法与遗传算法相结合的混合遗传算法对其PI调速器进行了优化设计,根据工程实际完成了调速系统的数学建模,并应用MATLAB6.5软件对遗传算法和传统PI算法的控制效果进行了仿真分析和比较,实践证明应用该方法能够有效的解决此问题。     

基于分数阶模糊PID控制的水轮机调节系统研究

针对水轮机调节系统中传统PID控制规律存在适应性不足的问题,设计了一种新型的分数阶模糊PID控制器(FOFPID),该控制器在模糊PID控制器(FPID)的基础上将微分及积分阶次进行从整数阶到非整数阶的拓展,并利用改进Oustaloup滤波算法对该控制器中的分数阶微积分进行数字实现.提出了一种基于Rechenberg五分之一法则的动态适应量子粒子群算法(DAQPSO),对水轮机调节系统控制器参数进行优化.仿真试验表明:FOFPID控制器在水轮机调节系统扰动幅度及运行工况变化时具有较强的适应性,并在水轮机调节系统参数发生变化时具有更好的鲁棒性;与QPSO,RLQPSO及MLQPSO相比,DAQPSO算法具有较好的计算精度,能为水轮机调节系统控制器提供更优的参数候选方案.     

基于分数阶模糊PID控制的水轮机调节系统

针对水轮机调节系统中传统PID控制规律存在适应性不足的问题,设计了一种新型的分数阶模糊PID控制器(FOFPID),该控制器在模糊PID控制器(FPID)的基础上将微分及积分阶次进行从整数阶到非整数阶的拓展,并利用改进Oustaloup滤波算法对该控制器中的分数阶微积分进行数字实现.提出了一种基于Rechenberg五分之一法则的动态适应量子粒子群算法(DAQPSO),对水轮机调节系统控制器参数进行优化.仿真试验表明:FOFPID控制器在水轮机调节系统扰动幅度及运行工况变化时具有较强的适应性,并在水轮机调节系统参数发生变化时具有更好的鲁棒性;与QPSO,RLQPSO及MLQPSO相比,DAQPSO算法具有较好的计算精度,能为水轮机调节系统控制器提供更优的参数候选方案.     

水轮机泥沙磨损两相湍流场数值模拟

为研究水轮机内部泥沙磨损的固液两相流动特性,应用基于计算多相流动力学理论中欧拉-欧拉方法的代数滑移混合多相流模型,采用多面体网格技术、标准k-ε湍流模型和压力速度耦合的SIMPLEC算法,转动区域应用多重参考系模型,对混流式水轮机全流道进行了三维定常泥沙磨损两相湍流场的数值模拟.利用商业CFD求解器ANSYS Fluent,获得了小开度工况下水轮机泥沙磨损发生的部位与程度,分析水轮机流道内泥沙磨损的特征规律,其中叶片上泥沙颗粒分布模拟结果与真机转轮实际磨损情况相符,表明该方法可以准确预测水轮机各过流部件的泥沙磨损情况,对揭示泥沙颗粒与水相互作用的固液两相湍流场诱发水轮机振动的影响机理及解决工程实际问题具有重要的意义,而且具有较高的工程应用价值.     

小型水电站水轮机改造研究与实践

小型水轮机由于存在设计不合理、技术手段落后、机电设备陈旧老化和效率低等问题,具有改造的必要性.从小型水电站水轮机存在的主要问题出发,提出了水轮机改造的措施、改造的技术途径,以及在改造中应注意的问题.并由此指导工程实际,得到了满意的结果.     

基于逆向设计理论的水泵水轮机设计与数值模拟

针对水泵水轮机效率普遍较低这一问题,借鉴低比转数混流式水轮机的叶片设计理论,对一给定参数的水泵水轮应用水轮机逆向设计理论对水泵水轮机进行水力设计、三维造型和ICEM网格划分;通过建立相对坐标系下的时均连续方程及N-S时均方程等控制方程组,利用标准k-ε湍流模型来封闭方程组,采用有限元体积法进行离散,离散方程的压力-速度耦合处理采用压力耦合方程组的半隐式(SIMPLEC)算法对水泵水轮机进行数值计算,得到其内流场流动特性,与试验的水泵和水轮机工况下压力分布对比分析,预测了水泵水轮机在设计工况下的转轮效率.数值模拟结果表明,基于逆向设计理论设计的水泵水轮机工况的最优效率可以达到91%,水泵工况的最优效率达到82%,充分说明应用逆向理论设计方法对水泵水轮机的设计,可以兼顾水泵工况和水轮机工况在较优的情况下运行.     

基于模拟退火算法的水轮机导叶分段关闭规律优化

为了解决水电站过渡过程中输水系统水锤压力和机组转速上升难以协调控制的问题,保证电站安全运行,建立了一种水轮机导叶关闭规律非线性优化模型,该优化模型可以调整各控制参数的重要程度并应用于多工况优化.基于水力瞬变计算的特征线法,应用模拟退火算法对该优化模型进行计算,寻找满足调节保证计算要求的较优关闭规律.结合工程实例,针对蜗壳末端最大压力和机组转速最大上升率2种控制工况,比较导叶一段直线关闭和二段折线关闭的数值计算结果,并应用模拟退火算法对折线关闭规律进行优化.使用优化后的关闭规律进行过渡过程计算,蜗壳末端最大压力、机组最大转速上升率和尾水管进口最小压力均满足调保计算要求,且安全裕量较大.结果表明,模拟退火算法可以快速优化导叶关闭规律,且算法稳定性较好,安全裕量分配合理,为类似工程的导叶关闭规律优化提供了新方法.     

考虑水轮机特性项的尾水调压室临界稳定断面公式研究

为了进一步研究水轮机特性对于调压室临界稳定断面的影响,结合调压室及水道局部模型、发电机及负荷局部模型、调速器局部模型,利用传递函数的思想,推导出了包含水轮机特性项的尾水调压室稳定断面直接表达公式,其中水轮机特性项可直接采用经验公式进行估算;实际工程案例分析表明,与规范公式相比,该公式计算结果与数值分析结果更为一致,安全性更高,因此采用推导的考虑水轮机特性的尾水调压室稳定断面公式有利于保障实际工程的安全。     

基于CFD的主轴密封泵板装置结构优化设计

为研究混流式水轮机主轴密封泵板装置内泄漏水流动特性,应用计算流体动力学软件,针对新疆红山嘴一级电站4号水轮机,将不同泵板装置作为研究对象,研究提高其水力效率的可行性以及对主轴密封降压的效果.在模型准确基础上对泵叶角度和泵盖高度分别改进,对两者联合结构共计22种改进模型进行数值模拟.研究结果表明:泵叶斜置45°且泵盖高度比为0.081 5的联合改进结构对主轴密封真空度提高率可达60.9%;泵盖高度比比泵叶角度改变对该装置水力效率提高更有利;泵盖存在“最不利高度比”,泵盖位置的确定需避免最不利高度比0.135 9.该研究结果将模型结构参数化使得结论的普适性有一定提高,为工程实际主轴密封设计改造提供了一定的理论依据.     

Overland water and salt flows in a set of rice paddies

Cultivation of paddy rice in semiarid areas of the world faces problems related to water scarcity. This paper aims at characterizing water use in a set of paddies located in the central Ebro basin of Spain using experimentation and computer simulation. A commercial field with six interconnected paddies, with a total area of 5.31 ha, was instrumented to measure discharge and water quality at the inflow and at the runoff outlet. The soil was classified as a Typic Calcixerept, and was characterized by a mild salinity (2.5 dS m⁻¹) and an infiltration rate of 5.8 mm day⁻¹. The evolution of flow depth at all paddies was recorded. Data from the 2002 rice-growing season was elaborated using a mass balance approach to estimate the infiltration rate and the evolution of discharge between paddies. Seasonal crop evapotranspiration, estimated with the surface renewal method, was 731 mm (5.1 mm day⁻¹), very similar to that of other summer cereals grown in the area, like corn. The irrigation input was 1874 mm, deep percolation was 830 mm and surface runoff was 372 mm. Irrigation efficiency was estimated as 41%. The quality of surface runoff water was slightly degraded due to evapoconcentration and to the contact with the soil. During the period 2001–2003, the electrical conductivity of surface runoff water was 54% higher than that of irrigation water. However, the runoff water was suitable for irrigation. A mechanistic mass balance model of inter-paddy water flow permitted to conclude that improvements in irrigation efficiency cannot be easily obtained in the experimental conditions. Since deep percolation losses more than double surface runoff losses, a reduction in irrigation discharge would not have much room for efficiency improvement. Simulations also showed that rice irrigation performance was not negatively affected by the fluctuating inflow hydrograph. These hydrographs are typical of turnouts located at the tail end of tertiary irrigation ditches. In fact, these are the sites where rice has been historically cultivated in the study area, since local soils are often saline-sodic and can only grow paddy rice taking advantage of the low salinity of the irrigation water. The low infiltration rate characteristic of these saline-sodic soils (an experimental value of 3.2 mm day⁻¹ was obtained) combined with a reduced irrigation discharge resulted in a simulated irrigation efficiency of 60%. Paddy rice irrigation efficiency can attain reasonable values in the local saline-sodic soils, where the infiltration rate is clearly smaller than the average daily rice evapotranspiration.     

瓦房店市水果生产标准化发展研究

瓦房店市是我国重要的水果生产基地,在国内水果生产领域占有重要地位。随着水果市场化的不断深入,如何满足和适应国内外市场需求成为瓦房店市水果生产的关键问题。从瓦房店市水果生产实际出发,阐述了实施水果生产标准化的必要性,提出了发展水果生产标准化的具体措施。     

金谷子耐旱TG118引种试种及推广应用

对引进的谷子新品种金谷子耐旱TG118进行品种比较试验和多点试种。结果表明：该品种抗旱、耐瘠、适应性强,稳产、高产、抗病抗风抗倒伏强,品质优良,粮草兼用,种植简单,省工易管;一般产量在6000kg/hm2以上,比当地主栽品种增产20%以上。最高产量达9450kg/hm2,适于在辽西北地区推广应用。     

对《种子法》存在问题的探讨

《种子法》是我国种植业第一部法律。自实施以来,为依法加强种子管理提供了有力的法律支撑,促进我国种子产业发生翻天覆地的变化。但随着依法管理工作的深入和种子产业的快速发展,《种子法》及配套规章的一些问题逐步显现出来。对《种子法》及配套规章存在的问题进行深入分析,对需要进一步补充的章节以及需要调整的内容进行深入探讨,以求更加完善和明确。     

Review of the Egyptian experience in implementing land drainage projects

About 30 years have passed since the Government of Egypt embarked on implementing a series of large scale drainage projects. At present, about 3.8 million acres have been provided with drainage systems on the basis of systematic pre-drainage investigations and designs. The target is to provide drains in approximately 6.4 million acres in the Nile Valley and Delta.The implementation of the subsurface drainage system is carried out by the public sector and private contractors under direct supervision of governmental regional departments. The implementation process depends on many factors related to the drainage material, machinery, manpower, site requirements, farmers and organizations involved. Problems and constraints are sometimes challenging, however, the annual rate of implementation has gradually increased to 170,000 acre/year.This paper discusses the different aspects involved in the implementation process of drainage systems. The development in materials, machinery and construction technologies will be reviewed. Institutional and management factors are going to be also considered.     

和谐社会理论建设的几点哲学思考

在新世纪,面对机遇和挑战,党的十六大把“社会更加和谐”作为全面建设更高水平的小康社会的一个重要目标。中国人素有社会和谐的理想;西方人自古也向往社会和谐;借鉴东西方两种和谐社会思想的经验、教训,构建社会主义和谐社会理论。     

A European irrigation map for spatially distributed agricultural modelling

We present a pan-European irrigation map based on regional European statistics, a European land use map and a global irrigation map. The map provides spatial information on the distribution of irrigated areas per crop type which allows determining irrigated areas at the level of spatial modelling units. The map is a requirement for a European scale assessment of the impacts of irrigated agriculture on water resources based on spatially distributed modelling of crop growth and water balance. The irrigation map was compiled in a two step procedure. First, irrigated areas were distributed to potentially irrigated crops at a regional level (European statistical regions NUTS3), combining Farm Structure Survey (FSS) data on irrigated area, crop-specific irrigated area for crops whenever available, and total crop area. Second, crop-specific irrigated area was distributed within each statistical region based on the crop distribution given in our land use map. A global map of irrigated areas with a 5′ resolution was used to further constrain the distribution within each NUTS3 based on the density of irrigated areas. The constrained distribution of irrigated areas as taken from statistics to a high resolution dataset enables us to estimate irrigated areas for various spatial entities, including administrative, natural and artificial units, providing a reasonable input scenario for large-scale distributed modelling applications. The dataset bridges a gap between global datasets and detailed regional data on the distribution of irrigated areas and provides information for various assessments and modelling applications.     

粉质仪和拉伸仪在面粉生产中的应用

在介绍粉质仪和拉伸仪结构和原理的基础上,探讨了粉质曲线中吸水率、形成时间、稳定时间、弱化度和评价值等指标与面粉品质的关系,以及如何根据拉伸曲线中面团最大拉伸阻力、延伸度和拉伸曲线面积等指标来评价面团品质,并结合生产实际,概述了粉质仪和拉伸仪在面粉生产中的作用。     

农村信息化服务的现状及建设措施

分析当前我国农村信息化服务的现状,提出加强农村信息化服务的新举措。     

车辆ABS控制算法的研究及探讨

对现代汽车的ABS控制算法作了一些简单的介绍,同时指出了它们的一些缺陷,相应地提出了几种对ABS的其它控制方法并加以探讨,其中着重论述了ABS门限值控制算法中参考车速的确定方法和基于附着系数的控制算法。