小水电站塑料压力管试验研究

河北省赞皇县黑龙潭水电站使用硬质聚氯乙烯管来代替水电站中常用的压力钢管。为推广应用聚氯乙烯管,了解其在小水电站中应用的一些主要力学性能,本文对该管进行了室内静载试验和现场动态观测分析,以研究在小水电站压力管道中用聚氯乙烯管代替钢管的可行性问题。     

埋藏式压力钢管加劲环抗外压稳定

埋藏式压力钢管加劲环的抗外压稳定分析有不同的计算理论和方法。运用ANSYS有限元软件对矩形和T形两种截面形式的加劲环进行了三维非线性有限元分析,得到了加劲环抗外压的临界外压值。计算结果表明,根据水电站压力钢管设计规范DL/T 5141-2001计算的临界外压值偏于保守;T形截面加劲环嵌固在回填混凝土中,利用回填混凝土承载,能够显著提高加劲环的临界外压值。本文对今后埋藏式压力钢管加劲环的结构优化设计具有一定的参考价值。     

埋藏式压力钢管加劲环抗外压稳定设计的改进研究

埋藏式压力钢管加劲环的抗外压稳定分析有不同的计算理论和方法.运用ANSYS有限元软件对矩形和T形两种截面形式的加劲环进行了三维非线性有限元分析,得到了加劲环抗外压的临界外压值.计算结果表明,根据水电站压力钢管设计规范DL/T 5141-2001计算的临界外压值偏于保守;T形截面加劲环嵌固在回填混凝土中,利用回填混凝土承载,能够显著提高加劲环的临界外压值.研究成果对今后埋藏式压力钢管加劲环的结构优化设计具有一定的参考价值.     

月牙肋岔管体形优化与设计

针对目前月牙肋岔管得到广泛应用的情况，根据新的《水电站压力钢管设计规范》DL/T 5141-2001，编制了内加强月牙肋岔管的体形优化设计程序。通过工程实例计算，表明该程序不仅有效地减小了工作量，提高了设计工作效率，而且大大提高了计算精度，可以为其它工程岔管的设计提供参考。     

对数正态分布随机变量在设计基准期内的最大值分布

对现行SD144－85《水电站压力钢管设计规范》中明管的可靠度进行校准分析时，由于有的荷载服从对数正态分布，且不知其在设计基准期内最大分布，以前采用某一时点的荷载分布通过一次二阶矩法求明管的可靠度，不够安全，而采用当随机变量服从对数正态分布时在设计基准期内最大值分布求明管的可靠度要安全得多。     

玻璃纤维增强树脂管在河东水电站的应用

针对水电站管道配置中钢筋混凝土管与钢管造价高且受压不能满足工程要求的问题，河东水电站首次将玻璃纤维增强树脂管──ＨＯＢＡＳ管应用在压力管道上。实践证明，将ＨＯＢＡＳ管应用在水电工程上，不但现场施工非常方便，而且管道的综合费用也大为降低，其优越性是很明显的     

喷灌用固定管道及其接头

在固定式喷灌系统中的干管和支管以及半固定式喷灌系统中的干管都是固定不动,多数是埋在地下,也有在灌溉季节铺设在地面上,灌溉季节过后立即折除,这都是固定管道,对这些管道只要求其在一定压力下(3-10公斤/厘米~2)通过一定的流量,经济耐用,重量大一些都不要紧。目前常用的固定管道有:铸铁管、钢管、予应力或自应力钢筋混凝土管、塑料管、石棉水泥管、玻璃管陶瓷压力管及石管等,管径一般为50-300毫米左右。     

小水电站使用球形岔管的实例

球形岔管是水电站压力管路中一种较新形式的岔管，其制造工艺较为复杂。文章介绍了广东省水利电力学校江湾实习水电站设计期间，从工程总体布置、水力计算、经济分析等方面对采用球形合管进行论证的情况，以及设计和制造的过程。对这种形式岔管的推广、应用，有参考借鉴价值。     

设置软垫层坝后背管结构非线性分

坝下游面钢衬钢筋混凝土管道是近30年来应用最广的压力管道型式之一,其工作机理是允许外包混凝土开裂，但要限制裂缝宽度。以三峡水电站坝后背管为例，借助有限元软件ANSYS建立了设置软垫层坝后背管有限元模型，计算分析了设置软垫层坝后背管结构应力状态，并与结构模型试验对比。结果表明：坝后背管设置垫层能有效减小钢管向外围混凝土传递的内水压力，降低混凝土拉应力峰值，改善外围混凝土结构的应力状态，提高钢管的承载比。随着垫层弹模的降低、厚度的增大，这种效应更加明显。对设置软垫层的范围提出了优化建议。     

焊接接头在里港水电站压力钢管安装中的应用

焊接接头在里港水电站压力钢管安装中的应用胡国节（安徽省潜山县水电局２４６００３）里港水电站是本地区第一座采用焊接接头作为压力钢管安装管道连接的电站。通过二年多运行的实践证明，管道安装采用焊接接头连接价格低，投资省，施工方便、安全，安装速度快、整体性好...     

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。