SPRINKMOD – pressure and discharge simulation model for pressurized irrigation systems. 1. Model development and description

A computer model was developed to simulate pressure and flow rate distribution along pipes and laterals of pressurized irrigation systems in operation. The software runs in a Windows environment and is capable of simulating irrigation systems having multiple pump stations combined in series and/or in parallel, booster pump stations, parallel pipes and looping pipes. Hand-move, wheel line and center pivot laterals with pressure regulators, one or two drop pipes per outlet and booster pump can be simulated. Leakage can be included in the main pipe network or along the laterals. Lateral inlet pressure can be set to an upper limit to simulate valve closure. Practically any type of nozzle and pump can be simulated since cubic spline functions are used to interpolate values from head-flow rate sets of data. To accomplish these capabilities, algorithms were developed and adapted to convert laterals into a set of head-flow rate data so that a simplified algorithm could be adapted to solve the entire pipe network. A user-friendly interface was designed to allow data for pumps, nozzle and pressure regulators to be interactively entered, edited and analyzed prior to the simulation run. The layout of the irrigation system can be drawn on screen using the mouse. Data can be independently entered and edited for each irrigation system component already drawn in the screen, at any time and in any order. Data for the entire irrigation system are verified at many levels before the simulation is run, to make the model less susceptible to crash. The model proved to be a practical tool for upgrading and designing pressurized irrigation systems. Received: 20 November 1997     

SPRINKMOD – pressure and discharge simulation model for pressurized irrigation systems. 3. Sensitivity to lateral hydraulic parameters and leakage

A computer model, SPRINKMOD, was tested with field data collected from a simple sprinkler irrigation system in operation. The original data for laterals and the amount and way leakage is considered were modified to evaluate the model sensitivity. The model predicted the pump station flow rate within 2% and the pump station pressure head within 5% with the original data collected. For this irrigation system, no practical effect was observed in the system operating point by changing the lateral pipe characteristics, lateral leakage amount and distribution, lateral pipe roughness and lateral local loss coefficient for flow past a riser outlet. The amount of leakage had more effect on the model simulation of pressure heads than the way leakage was considered, localized or distributed along the laterals. The use of a variable local loss coefficient, K _r, along the 350-m hand-move laterals had a negligible effect on both system operating point and distribution of pressure heads along the laterals. Received: 14 February 1998     

SPRINKMOD – pressure and discharge simulation model for pressurized irrigation systems. 2. Case study

A computer model, SPRINKMOD, was tested with field data collected from a complex sprinkler irrigation system in operation. The original data collected were adjusted in order to calibrate the model for the irrigation system. Five modifications were made in the original data so that the model sensitivity could be evaluated. The model predicted the system operating point with less than 1% error, after some adjustments in the data. The relative mean standard error was 4.1% for the upstream pressure heads and 2.1% for the downstream pressure heads of all laterals analyzed together. Measurement of pressure and discharge at pump stations along with a reasonable estimate of leakage appears to be essential for simulation of old systems. Adjustments made to pipe wall thickness and pipe roughness were not as important as the adjustments made to the lateral valves closure in getting SPRINKMOD to simulate pressure heads that were close to the measured values. For long laterals, like center pivot laterals, a variable local loss coefficient for flow past a riser outlet worked better than a fixed value of 0.3. Received: 24 November 1997     

沼气.畜牧业.农业

沼气是一种可再生的生物质能源,可以就地生产,就地使用,成本低,见效快,是理想的廉价的优质气体燃料。各地实践证明,办沼气是利国利民、一举多得的好事。当前,农村柴油、电力和煤碳供应比较紧缺,发展沼气尤其必要。沼气可供烧水、煮     

草儿.父亲.电网

正草儿的父亲年轻时高大、俊朗、乐善,穿着深蓝色工作服,工作在大山外面,是个十分优秀的青年。那时虽清贫,但他们一家却过得很幸福,唯一让草儿感到遗憾的就是父亲经常十天半月的不着家,农活全部落在母亲的身上。每当看到隔壁三叔背着虎子去赶集,草儿的心里就极不是滋味儿。有一次她问父亲:"你啥时候带着我去赶集呢?"父亲便承诺说等到过年的时候。于是草儿就盼呀盼呀,可过了一年又一年,父亲的许诺总是     

G.W.S.人造上的研究

介绍了作者开发的一种人造土。这种人造土由聚醋酸乙烯(P.V.A.)胶(G)、水(W)和硅砂(S)按一定比例混合而成,称为G.W.S.人造土,用以模拟田间土壤供小型土槽用。通过大量的样本试验及试验数据的处理,给出了G.W.S.人造土的成分比例、干燥方式、干燥时间与强度的关系曲线及回归方程,使用者可以根据需要选择使用。     

Response of grapevine cv. ‘Tempranillo’ to timing and amount of irrigation: water relations, vine growth, yield and berry and wine composition

The effects of several moderate irrigation regimes on vine water status, yield, and must and wine composition, were investigated during five seasons in a vineyard planted with Vitis vinifera cv. Tempranillo. Treatments consisted of non-irrigated vines and six differentially irrigated treatments with contrasting watering regimes during the pre-veraison and post-veraison periods. There were large differences in yield and grape and wine quality responses to irrigation among seasons, probably as consequence of the different environmental conditions and crop levels. It was, however, clear that vines benefit more of the irrigation supplied in years of high yield levels. Across seasons, yield increased in proportion to the amount of water applied mostly due to the larger berries of irrigated vines, and there was no clear response to the timing of irrigation supplied. In addition, there were no carry over effects due to irrigation on bud fertility. The post-veraison water application was necessary to increase must sugar level and wine alcohol content. However, water restrictions during the pre-veraison period lead to more concentrated berries in terms of total phenolic and anthocyanins. The only noticeable detrimental effect of irrigation, regardless of the timing of its application, on wine composition was an increase in wine pH.     

农机配件商品质量监督抽样.检验.判定

农机配件商品质量监督、抽样、检验、判定江苏省农业机械试验鉴定站蔡国芳目前，农机零配件商品质量监督检验缺乏统一的抽样标准和做法，一般依据国家标准、行业标准或企业标准抽样检验判定。根据抽样检验标准体系理论，上述标准属验收性标准，用于监督抽查型检验不尽合理...