不同类型滴灌带灌水均匀度的田间测试分析

以4种不同类型滴灌带为材料,在田间测定不同压力条件下滴灌带管末压力损耗变化和单孔出水量变化,不同压力、滴孔间距和管壁厚度对滴灌带灌水均匀度的影响。结果表明:随管入口压力增强,滴灌带压力损耗均增大,以D型滴灌带损耗最大;单孔流量随压力增强也增大,在相同压力条件下D型滴灌带单孔流量明显高于其他3种滴灌带;灌水均匀度随入口压力增强而升高,随滴孔间距增大先升高后降低,随管壁厚度增加而升高。4种滴灌带灌水均匀度以C型最高(Eu98%),受入口压力变化影响小;B型居中,A型和D型较低;在生产实际中应根据田间实际情况,确定适宜的滴灌系统工作压力,选择适宜滴孔间距和管壁厚度的滴灌带,提高灌水均匀度,降低运行成本。     

干旱区农田滴灌带"一带两用"灌水均匀度和堵塞率研究

开展不同水氮梯度对滴灌带灌水均匀度和堵塞率等水力性能研究,对干旱区滴灌"水肥一体化"技术的应用推广具有重要意义.以南疆阿克苏地区冬小麦、复播玉米生育期内的滴灌带为研究对象,应用滴灌带水力性能综合测定平台对滴灌带进行检测,探究不同水氮处理下滴灌带长期使用(12个月)后灌水均匀度及堵塞率的变化规律.结果表明:相同滴灌水量,灌水均匀度随施氮量的增加而减小,高肥水平的灌水均匀度均最小,氮肥施用量是造成滴灌带堵塞的一个重要因素.建立灌水均匀度回归预测模型,可知灌水均匀度随平均流量偏差的增大而减小,平均流量偏差Δ---q对灌水均匀度Cu影响较大.高水低肥和中水中肥处理下的灌水均匀度均达到80％以上,说明滴灌带"一带两用"在适宜的水肥配比下可以满足作物的水肥需求,该技术可节约滴灌带使用量,减少亩投资,为滴灌"水肥一体化"技术的推广应用提供技术支持.     

2种滴灌带灌水均匀度对铺设长度和进水压力的响应

【目的】探究滴灌带进水压力和铺设长度对灌水均匀度的影响。【方法】以内嵌式滴灌带和薄壁式滴灌带为研究对象,比较了4种滴灌带铺设长度和4种进水压力交互作用下的灌水均匀度。【结果】内嵌式滴灌带的灌水均匀度较薄壁式滴灌带表现更好,且更适合于较长距离铺设使用。建立了2种滴灌带灌水均匀度与滴灌带铺设长度和进水压力的数学回归模型,并利用回归方程寻优发现内嵌式滴灌带滴灌均匀度达到0.95以上的优化铺设长度和进水压力的组合为:铺设长度60.02~109.94 m,进水压力0.09~0.2 MPa;薄壁式滴灌带的优化铺设长度和进水压力的组合为:铺设长度60.05~92.67 m,进水压力0.05~0.2 MPa。【结论】在设计田间滴灌系统时2种滴灌带的铺设长度和进水压力应在上述范围内选取,以保证灌水均匀度满足要求。     

单翼迷宫式滴灌带的关键参数与灌水均匀度的响应关系

为探究单翼迷宫式滴灌带坡度、进水压力和铺设长度对灌水均匀度的影响,以3种单翼迷宫式滴灌带为研究对象,以灌水均匀度作为评价指标,采用UL₉(3⁴)均匀正交设计试验,比较了3种不同流量的单翼迷宫滴灌带在进水压力、铺设长度和坡度作用下的灌水均匀度的变化规律。经直观分析、方差分析和多重比较进行综合评价,再由SPSS和PPR对试验数据进行数学建模。结果显示,3种单翼迷宫式滴灌带灌水均匀度的外界因素排序均为压力>坡度>长度,相比于SPSS、PPR所建立的模型具有更高的精度。研究成果不仅为灌水均匀度计算与预测提供了理论依据,还对各学科试验优化设计、高维数据建模分析提供了有效的解决方案。     

不同类型滴灌带灌水均匀度田间试验分析

"十二五"规划中指出发展节水灌溉的同时保证低能耗,为此,低压低能耗的微灌技术将成为未来节水灌溉发展的核心。实验选取了自治区节水灌溉重点县自动化滴灌示范基地中使用较多的两种不同类型滴灌带作为研究对象,分析了不同铺设坡度、铺设长度、入口压力等对滴管带灌水均匀度的影响。结果表明,该自动化滴灌示范基地中采用的两种滴灌带均能满足设计的灌水要求,均匀度良好。从试验结果中还发现A型滴灌带在低压条件下进行灌水均匀度良好,综合分析且在耗能上较B型滴灌带低,能够达到低压低能耗微灌技术的要求。     

低压滴灌灌水均匀性研究

灌水均匀度是衡量滴灌系统灌水质量和水力设计的重要指标,为探究低压条件下提高灌水均匀度的方法,试验以压力补偿内镶式滴灌带和压力补偿圆柱式滴灌管为材料,测定不同毛管入口压力、敷设长度、灌水器间距的滴头流量分布及灌水均匀度。结果表明,在低压条件下,滴灌灌水均匀度随毛管入口压力的增大及敷设长度的减小而提高,随灌水器间距的增大而缓慢降低,其中毛管敷设长度影响最大,毛管类型次之,灌水器间距最小,当两种滴灌毛管入口压力在2~5 m时,灌水均匀度均高于85%,且随入口压力的减小而缓慢降低,入口压力在0.5~2 m时,灌水均匀度显著降低,压力补偿内镶式滴灌带灌水均匀度低于80%,但压力补偿圆柱式滴灌管灌水均匀度仍高于80%;当两种滴灌毛管敷设长度在40~70 m时,灌水均匀度均高于85%,且随敷设长度的增大而缓慢降低,敷设长度在70~90 m时,灌水均匀度显著降低,当压力补偿内镶式滴灌带和压力补偿圆柱式滴灌管的敷设长度分别大于75、85 m时,灌水均匀度均低于80%。因此,为满足工程设计对滴灌灌水均匀度不低于80%的要求,压力补偿内镶式滴灌带入口压力不低于2 m、敷设长度控制在75 m以内,压力补偿圆柱式滴灌管入口压力不低于0.5 m、敷设长度控制在85 m以内;为有效降低工程投资,工程设计可适当增大滴灌毛管灌水器间距。     

无机吸附剂处理黄河水滴灌抗堵塞试验研究

为了解决黄河水滴灌中泥沙处理的问题,利用黄河泥沙配置出高、中、低3种含沙量水质的试验组,采用“水梦”无机吸附剂泥沙分离装置过滤3种水质进行滴灌堵塞模拟试验,监测水质变化情况并进行滴灌的抗堵性试验;观测2种滴灌带沿程流量变化规律、滴灌系统均匀度以及系统相对平均流量变化规律.结果表明:经“水梦”无机吸附剂泥沙分离装置处理后,不同含沙量下水体中的浊度及各类污染物指标得到明显降低,其中总氮、总磷、COD,BOD、浊度平均降低了23.9%,40.3%,47.0%,38.3%,97.8%.模拟大田滴灌进行8次灌水试验,依据2种滴灌带试验过程中灌水均匀度及灌水相对平均流量的变化情况可知,在实际使用过程中应采用流量更大、滴头类型为内镶贴片式的滴灌带.     

基于灌水小区的射流三通灌水均匀度试验研究

为探究支、毛管射流三通组合的水力特性,用支管射流三通、普通支管三通与毛管射流三通、普通毛管三通组成了4组灌水小区,对不同总进口压力水头(9.5、12、14、15.5 m水头)和不同滴灌带长度(60、70、80 m)下的射流三通组合进行水力性能研究。试验结果表明:总进口压力相同时,连接射流三通的滴灌灌水器的平均流量要小于普通三通;进口压力和滴灌带长度相同时,Ⅰ号灌水小区灌水均匀度最高,Ⅳ号灌水小区灌水均匀度最低,且Ⅰ号灌水小区灌水均匀系数比Ⅳ号提高了2.56%～3.32%,流量偏差率降低了5.06%～8.20%;滴灌带长度相同时,4种灌水小区灌水均匀系数随进口压力的增大整体呈上升趋势;进口压力相同时,灌水均匀系数随滴灌带长度的增加而减小。该研究结果为新型灌水小区的开发与应用提供理论基础。     

低压滴灌条件下提高系统灌水均匀度的途径探讨

低压滴灌是一种高效节能型灌水技术,采用低压滴灌不仅可以减少灌溉系统建设成本,而且可以降低系统运行成本,因此低压滴灌将是今后滴灌技术发展的一个重要方向。然而在灌水器工作压力小于5 m的低压条件下,采用现有的滴灌设备将会由于水力环境的变化引起毛管输水量和滴灌管(带)的有效铺设长度减小,降低滴灌系统的灌水均匀度和灌水质量等问题,为了不以牺牲灌水质量换取成本降低,通过分析低压滴灌的工作特点,提出了改进和提高低压滴灌灌水均匀度的方法和途径。     

地下滴灌应用试验研究

将孔口式、发丝管式和内镶式滴灌带等三种常用的灌水器应用于地下滴灌系统,并进行田间试验,分析其流量变化规律、灌水均匀度及对堵塞的敏感性,探讨地下滴灌技术的适用性。结果表明,地下滴灌技术在实践中是可以运用的,但仍需对灌水器选择及系统布置等方面开展研究     

Water and nitrate distributions as affected by layered-textural soil and buried dripline depth under subsurface drip fertigation

Laboratory experiments were conducted to investigate the distributions of water and nitrate from a buried dripline discharging an ammonium nitrate solution in uniform and layered-textural soils. Two layered soils, a sandy-over-loam soil (SL) and a loam-sandy-loam soil (LSL), and two uniform soils of sandy (S) and loam (L) were tested. The experimental results demonstrated that dripline depth and layered-textural soil greatly affected water and nitrate distribution. Wetted depth increased with dripline depth and initial soil water content for both uniform and layered soils. The distribution pattern of water in the layered soils was controlled by the layering sequence and the dripline position relative to the interface between two soil layers. Water accumulation occurred in the fine-textural layer of soil for the layered soils. For the sandy-over-loam soil (SL), positioning the dripline below the interface led to much water (89%) moving to the sublayer of loam soil than positioning the dripline above the interface (73%). For the loam-sandy-loam soil (LSL), positioning the dripline in the top layer of loam soil resulted in 77% of water applied distributed in the top layer, while positioning the dripline in the bottom layer of loam soil resulted in 93% of water applied distributed in the bottom layer. Measurements of nitrate distribution showed that nitrate concentration in the proximity of the dripline and of the water accumulation zone approximated the input concentration while nitrate accumulated at the boundary of the wetted volume for both uniform and layered soils tested. The results from this study suggest that the dripline depth should be carefully selected in the design of subsurface drip irrigation systems for layered soils to obtain a target distribution of water and nitrate.     

Distribution of rainfall and soil moisture content in the soil profile under citrus tree canopy and at the dripline

The plant canopy intercepts rain and thus can alter the distribution of water under the canopy as compared to that along the dripline. The effects of a citrus (Citrus sinensis L. Osbeck) tree (25-year-old, Valencia orange) canopy on the distribution of rainfall and soil moisture content within the soil profile either along the dripline (D) or under the canopy near the trunk (inner side; I), and midway between I and Dripline (M) were evaluated, on the east and west sides of trees planted along north-south rows. Results of eleven storm events in 1995 (mean of east and west sides) revealed that the amounts of precipitation at the D, M, and I positions were 97–140, 47–94, and 52–79% of the incident rainfall, respectively. Thus, canopy interception of incident rainfall was quite appreciable. The soil moisture content was greater along the dripline compared to that at the M and I positions, particularly in the deeper (≥60 cm) soil profile. The water flux was significantly greater at the dripline than under the canopy indicating a greater leaching potential of soil-applied fertilizers and other chemicals when placed along the dripline. A substantial reduction in the rainfall and water flux under the canopy as a result of canopy interception suggests that application of fertilizer and chemicals under the canopy could minimize leaching losses. Received: 10 November 1997     

Effect of flushing frequency on emitter clogging in microirrigation with effluents

Flushing is an important maintenance task that removes accumulated particles in microirrigation laterals that can help to reduce clogging problems. The effect of three dripline flushing frequency treatments (no flushing, one flushing at the end of each irrigation period, and a monthly flushing during the irrigation period) was studied in surface and subsurface drip irrigation systems that operated using a wastewater treatment plant effluent for three irrigation periods of 540 h each. The irrigation systems had two different emitters, one pressure compensating and the other not, both molded and welded onto the interior dripline wall, placed in laterals 87 m long. Dripline flow of the pressure compensating emitter increased 8% over time, while in the nonpressure compensating emitter, dripline flow increased 25% in the surface driplines and decreased 3% in the subsurface driplines by the emitter clogging. Emitter clogging was affected primarily by the interactions between emitter location, emitter type, and flushing frequency treatment. The number of completely clogged emitters was affected by the interaction between irrigation system and emitter type. There was an average of 3.7% less totally clogged emitters in flushed surface driplines with the pressure compensating emitter as compared to flushed subsurface laterals with the nonpressure compensating emitter.     

Effect of filter, emitter and location on clogging when using effluents

The effect on emitter clogging of four filtration systems (sand, screen, disc and a combination of screen and disc filters) and six emitter types placed in laterals 87 m long, using two different effluents with low suspended solid levels from a wastewater treatment plant, was studied for 1000 h. Four of the emitters were molded and welded into dripline wall, two of them being pressure-compensated and the other two non-pressure-compensated. The other two emitters, both pressure-compensated, were inserted into thick wall. Emitter clogging was affected mainly by emitter type, location along the lateral and the interaction between these two factors. Differences among emitters with larger clogging were only observed at the end of dripline. Two molded and welded emitters showed the worst performance: one non-pressure-compensated with the lowest passage section, and the other pressure-compensated that, after 800 h working at higher dripline flow and particle load, experienced an important decrease in flow rate. Only with the effluent that had a higher number of particles, did the filter and the interaction of filter and emitter location have a significant effect. Emitters placed after screen and sand filters showed the largest flow rates at the lateral ending, even though only sand filtration significantly reduced turbidity and suspended solids. Emitters protected by a disc filter experienced the largest flow rate reductions.     

基于Windows的PC机与单片机通信程序设计

随着微机测控系统的发展，人们对测控系统的要求越来越高。用户要求所使用的系统具有良好的人机交互模式，由此利用单片机具有的实时数据采集和微机对图形处理、显示的优势，结合Windows环境下的PC机良好的操作环境，使PC机与多单片机结合的网络测控系统越来越占主导地位。如何更好地在Windows平台下实现PC机与单片机的通信设计，成为测控系统中一个关键技术问题。为此，详细阐述了两种程序设计的方法。     

不同冲洗措施下迷宫流道灌水器泥沙运行分布机理研究

评估了3种冲洗流速（0.25、0.50、0.75m/s）和5种冲洗频率（2d冲洗1次、4d冲洗1次、7d冲洗1次、10d冲洗1次和无冲洗对照组）对内嵌式齿形迷宫流道灌水器抗堵塞性能的影响,利用激光粒度仪对水源泥沙、滴头排出泥沙、滴头内滞留泥沙进行级配对比和粒径分析,并对不同冲洗处理下灌水器的相对流量和灌水均匀度进行拟合。结果表明：冲洗处理对齿形迷宫流道灌水器抗堵塞性能有显著影响,12种冲洗处理提高了内嵌式齿形迷宫流道灌水器的输沙能力,使滴头使用年限平均提高了39.58%;在冲洗作用下,泥沙凝聚沉降的机会降低,流道内小颗粒泥沙及时排出,没有形成体积较大的团聚体,滴头堵塞形成缓慢,灌水均匀度和流量系数下降缓慢;冲洗处理能有效减少毛管内泥沙堆积,降低大颗粒泥沙进入迷宫流道的机率,从而提高了齿形迷宫流道灌水器的抗堵塞性能。     

基于主成分分析与Brovey变换的ETM+影像植被信息提取

在ETM 影像全色波段和多光谱数据融合时,Brovey变换是一种较好的融合方法,但是Brovey变换所利用的波段信息量少,并且在对融合后影像分类时常将存在阴影的植被覆盖区误判为水体。因此将主成分和归一化植被指数(NDVI)作为Brovey变换融合时的波段,实验结果显示融合后的影像更利于后期植被信息提取。     

自动化温室测控系统的设计

温室测控系统是对温室环境囚素(如温度、湿度和CO2浓度等)进行相应地修正或调整，使植物生长处于最佳或相对最佳的生长环境条件中。为此，介绍了自动化温室测控系统的工作原理和系统的硬件实现方法，并说明了软件的设计及功能。     

不同天气条件下连栋温室内光照分布规律研究

温室内的光照环境对作物的生长具有重要意义.为此,主要研究了不同天气条件下华东地区连栋塑料温室中光照分布的日变化规律.研究结果表明:多云天气条件下,温室内光照分布均匀只是相对的;而晴天情况下,温室内的整体光照条件比较好,但光照分布相对不均匀,且透光率比多云天气低.实验结果为温室光环境模型的建立以及进一步的光环境调节和控制提供了参考.     

温室CO2浓度测控仪设计

介绍了一种温室CO2浓度测控仪设计方案。系统硬件采用单片机为核心,外扩适量ROM存放系统程序、人机对话接口键盘、显示器、打印机、传感器和A/D转换接口,并通过串行口连接上位机;软件采用模块化设计,分为主程序模块,数据检测分析处理模块等。