Integrated decision making for reservoir,irrigation, and crop management

An integrated approach to reservoir, irrigation, and cropping management which links four different models—a hydrologic model (PRMS), a crop growth simulation model (EPIC), an economic model based on linear programming, and a dynamic programming model—is developed and demonstrated. The demonstration is based on an irrigation district located in a subhumid climate with an irrigation reservoir large enough for over-year storage. The model is used to make repeated simulations for various planning horizons. Two different types of results are presented. The first provides the probability that each of the various farm plans (land/crop/water allocation) will be chosen as the optimum in the first year of the planning horizon. The second approach provides probability distributions of accumulated revenues over a chosen length of planning horizon. Each distribution is associated with an initial reservoir level and a particular farm plan in the first year of the planning horizon. The consequence of selecting certain farm plans at the beginning of a specified planning horizon is therefore quantified in a probabilistic way. Based on families of probability–revenue curves, an irrigation manager can simultaneously evaluate crop, irrigation, and reservoir management options.     

吉林大学地面机械仿生技术教育部重点实验室

吉林大学地面机械仿生技术教育部重点实验室是在机械工业部1992年批准建立的地面机械仿生技术部门开放研究实验室基础上,由教育部于2000年8月批准建立的,是国内唯一从事仿生学研究的教育部重点实验室.实验室1993年开始对外开放,是吉林大学农业机械化工程国家重点学科的依托单位.     

浅谈沼气、水煤气、液化石油气三种气源掺混联供在南阳市管道燃气中的应用

沼气、液化石油气、水煤气三种燃气均为优质燃料，都可以单独作为气源使用，但要把三种气源有机地结合起来掺混综合利用，难度很大，本文重点介绍了三种气源的合理掺混比例，使用效果，共同行参考。     

Leaching requirement for salinity control III. Barley,cowpea, and celery

Leaching requirement, the smallest steady-state leaching fraction which prevents any loss in crop yield, was determined for barley, cowpea, and celery in field plots at the U.S. Salinity Laboratory. Six replicated leaching-fraction treatments were irrigated many times each day with small quantities of water having an electrical conductivity of 2.3 dS/m. The crops were grown in succession between January 1979 and September 1981.The leaching requirement (L_r) was 0.10 for barley grain and 0.13 for barley forage. For cowpea seed, L_r was 0.16; 0.17 for cowpea forage. L_r for celery was 0.14. These experimentally determined values for barley and cowpea seed are higher by about 0.05 than those predicted by a leaching-requirement model based on an exponential crop water-uptake pattern. The experimental values for celery and cowpea forage are lower than predicted values by 0.06. These differences are not considered significant, however, when considered in terms of the small differences in water applications (about 25 mm) to cause these changes in L_r. Evapotranspiration during each crop's growing season coincident with L_r was 410, 630, and 460 mm for barley, cowpea, and celery, respectively.     

Changing systems for supporting farmers' decisions: problems,paradigms, and prospects

All correct reasoning is a grand system of tautologies, but only God can make direct use of that fact. The rest of us must painstakingly and fallibly tease out the consequences of our assumptions. (Herbert Simon in ‘The Sciences of the Artificial’, p.15)

Decision support systems (DSS), like other information systems (IS) before them, were designed to serve functions deemed by ‘management scientists’ to be potentially useful to managers. But the unwelcome fact is that the use of agricultural DSSs by managers of farms has been low. This paper probes possible reasons for this through interpretation of agricultural DSS case histories and several strands of relevant social theory. From nine cases of DSS development effort and 14 products interpreted comparatively, a number of generalisations are made that serve as reference points in the following search for explanation in theory.First, the nature of management practice of family farms is explored and differences between the internal structure governing personal action and the scientific approach to practice are contrasted. Next, the interaction between the nature of the particular action/practice and the nature of the DSS is explored. A DSS designed to provide integrated, optimal recommendations for management typifies the DSS as a proxy for a manager's decision process. Examples of elaborate expert systems that simply were not used dramatically illustrate the resistance of family farmers to have their decision processes by-passed. On the other hand, the DSS designed to serve as a tool in a modified decision process is shown to have experienced higher use, by deriving and exploiting ‘deep,’ abstract information about the system, by introducing a powerful ‘logic,’ or a combination of both.A number of the referenced case stories demonstrate the resurgence of the decision support mode whereby the simulator is in the hands of an expert intermediary as an alternative to easy-to-use software in the hands of a farmer. This is the mode of operational research/management science, which preceded the DSS.In comparison with hierarchical organizations, available options for overcoming the persistent ‘problem of implementation’ of the DSS in family farms are inherently weak. This focuses attention on the importance of the relationship between the DSS developer and the potential user. Drawing on a classic typology of possible configurations of ‘understanding’ between the scientist and the manager, four approaches to intervention are discussed. Three entail a degree of engagement that qualifies them as ‘participative.’ But one of these constitutes a departure from the DSS and broader IS traditions that places it in another paradigm. In this ‘mutual understanding’ relationship, intervention intent shifts from educating and persuading to recognition of and respect for other ways of viewing the world. This opens up the opportunities for co-creating information systems that utilise the comparative advantages of both practical and scientific knowledge. Intervention emphasis shifts from prescribing action to facilitating learning in actions.Although the DSS has fallen far short of expectations in its influence on farm management, the experience has been instructive in multiple ways to both farmers and professionals in agriculture. In many cases, farmers learned from the DSS and could then jettison it without loss. From disappointments scientists have sometimes learned what was needed to achieve a better outcome. From collated DSS experiences, important lessons for the future can be drawn.The paper concludes by conjecturing that the future of the DSS and related ISs, while more limited than once imagined, holds promise in four directions: a ‘small’ tool for aiding farmers' tactical decisions; a versatile simulator as a consultant's tool; a versatile simulator as the core of a facilitated ‘learning laboratory,’ and a formal framework that supports regulatory objectives in constraining and documenting farming practice.     

Leaching requirement for salinity control I. Wheat,sorghum, and lettuce

Crop productivity and water use efficiency when saline irrigation water is used are highest when efficient irrigation systems are managed to meet the crop's leaching requirement. The objective of this experiment was to establish the leaching requirement. The objective of this experiment was to establish the leaching requirements for frequently irrigated wheat, grain sorghum, and head lettuce. The 4-year study in field plots consisted of six replicated leaching fraction treatments. The plots were pulse-irrigated daily with water having a total dissolved salts concentration of 1350 mg/l.The leaching requirements are 0.08 for wheat and sorghum, and 0.26 for lettuce. The respective evapotranspiration during each crop's growing season coincident with the leaching requirements was 440, 550, and 245 mm. A pan factor of 0.7 was consistent among these three crops at their respective leaching requirements. With daily irrigation, 90% of the crop's water uptake occurred above a soil depth of 0.6 m, independent of leaching fraction.     

中国节水灌溉装备发展现状、问题、趋势与建议

节水灌溉装备在提高农业用水效率、农民增产增收及生态环境建设等方面发挥着重要作用,对于缓解水资源短缺矛盾、保证国家粮食安全、推动农村经济可持续发展具有重要的战略地位。经过近60 a 的发展,节水灌溉装备在理论研究、技术水平等方面取得了长足进步,生产规模基本能满足中国节水灌溉发展的需要,但自主研发能力较弱,在产品质量、技术性能、可靠性等方面还有待于进一步提高。加强基础理论研究,提高自主创新能力,研发多功能、低能耗、低成本、智能化、精准化、绿色化的节水灌溉装备,是今后的发展趋势。建议开展丘陵山区节水灌溉综合配套技术与装备的研究,研制多功能、智能化精确喷灌机组,开发低成本高效水肥药协同精准灌溉技术与装备,研究清洁能源节水灌溉装备与技术,促进我国节水灌溉装备行业的健康全面发展。     

Correcting soil water balance calculations for dew, fog, and light rainfall

In Mediterranean climates, adoption and use of the ET-based scheduling method is limited to regions characterized by considerable contributions to evapotranspiration from fog interception, dew, and light rainfall. While the crop evapotranspiration is often accurately estimated, the water balance is frequently in error because a considerable portion of the energy expended is used to vaporize water from the plant surfaces rather from inside the leaves (i.e., transpiration). Growers in regions with considerable fog, dew, and light rainfall are hesitant to use ET-based scheduling because the cumulative crop evapotranspiration between irrigations is often considerably higher than the soil water depletion. A correction for these surface contributions is clearly needed to improve the water balance calculations and to enhance adoption of the ET-based scheduling method. In this paper, we present a simple, practical method to estimate the contribution of fog interception, dew, and light rainfall to daily crop evapotranspiration, and we show how to use the method to improve water balance calculations.     

Evaluation of irrigation schemes for sugarcane in Sindh,Pakistan, using SWAP93

A computer simulation model, SWAP93, was used to simulate the soil water balance of sugarcane (Saccharum officinarum L.) over a period of 6 years, in order to develop an efficient irrigation scheduling scheme for Sindh, Pakistan. Given the limitations and inflexibility of the existing warabandi irrigation system, which does not allow on-demand irrigation, only irrigation depth and irrigation interval were varied in order to assess the best irrigation depth/interval combination for sugarcane production. Twelve irrigation treatments were simulated. These treatments were four irrigation amounts (900, 1200, 1650 and 1800 mm) and three irrigation frequencies (7, 10 and 15 days). Three seasons with rainfall totaling less than 20 mm were compared with three seasons of over 200 mm rainfall. Two approaches were used in assessing the irrigation schemes: yield parameters and water management response indicators. Treatment parameters (e.g. irrigation amounts, weather conditions, soil characteristics, etc.) served as input for SWAP93, actual transpiration was calculated and then used in a crop water production function to predict yield and water use efficiency. Additionally, water management response indicators were derived from model outputs, and used to assess the impact of the schemes on soil salinity and water logging. Both these indicators and the yield and water use efficiency indicated that a seasonal total of 1650 mm, applied at a 15-day interval was the best irrigation scheme for the region.     

Leaching requirement for salinity control. II. Oat,tomato, and cauliflower

Leaching requirement, defined as the minimum leaching fraction that maintains full crop production, was determined in field plots at the U.S. Salinity Laboratory for three crops; oat, tomato, and cauliflower. Six replicated leaching-fraction treatments were pulse-irrigated daily with water having an electrical conductivity of 2.1 dS/m. All three crops were grown in rotation during 1977 and 1978 with a third tomato crop in 1979.The leaching requirement (L_r) was 0.10 for oat grain, 0.21 for tomato fruit, and 0.17 for cauliflower heads. For oat forage, the L_r was more than 0.17. These values agree closely with those predicted by a leaching-requirement model based on an exponential crop water-uptake pattern. Evapotranspiration during each crop's growing season coincident with the leaching requirement was 390, 850, and 230 mm for oat, tomato, and cauliflower, respectively.     

管道（压力容器）泄漏检测仪的改造与应用

1　问题的提出在现代工厂、电厂、抽水站等工程的机电安装施工及检修中 ,高压电缆的使用是普遍的。其终端头、中间接头 (下文称高压电缆头 )是高压电缆的重要部件 ,且数量多、制作工艺复杂 ,其制作质量的优劣直接影响到高压电缆及机电设备的经济、安全运行。高压电缆头的质量检测 ,通常的方法是在电缆头制作完毕后进行交流耐压试验和直流泄漏试验。二者均属破坏性试验 ,且有时电流泄漏值小于标准泄漏值 ,可判为合格。但往往投运一段时间 (特别是满负荷运行 )后 ,这些本为合格的高压电缆头 ,其泄漏部位会逐渐灼伤、老化。加之温度、湿度等环…     

基于遗传算法的柴油机自适应智能调速控制系统

介绍了利用智能控制技术和计算机控制技术设计的车用柴油机自适应智能调控控制系统，该系统将人工智能中的神经网络控制技术，模糊控制 技术和遗传算法有机地结合起来，用单片机实现对柴油机转速的自适应智能自动控制，试验表明，这种控制系统具有较高的自学习性和鲁棒性，控制精度高、速度快。     

广州南沙滨海景观带上卧式闸门结构设计

目前城市防洪排涝工程建设越来越重视景观协调性,传统平面直升闸门已无法满足广州南沙滨海景观带建设的要求,万顷沙挡潮闸推荐上卧式闸门,采用液压启闭机起吊,该类型闸门地面以上无高耸建筑,做到建闸于无形。通过受力系统简化,对面板、主梁进行了计算。将闸门简化为平面问题,采用静力学方法对不同水位组合情况下的启闭力进行计算,为启闭机容量选择提供依据。同时通过受力平衡分析,计算得到了中铰的支座反力,从而为中铰牛腿的结构计算提供荷载要求。     

Peak crop coefficient values for Shaanxi,North-west China

Lysimeter and soil water instruments were used in North-west China to determine peak crop coefficients and calibrate irrigation scheduling software developed for commercial use in Scotland. The (1963) Penman equation, previously used in Scotland, was compared with a particular formulation of the Penman–Monteith (PM) equation proposed by Allen et al. [Allen, R.G., Smith, M., Perrier, A., Pereira, L.S., 1994a. An update for the definition and calculation of reference evapotranspiration. ICID Bull. 43 (2), 1–34; Allen, R.G., Smith, M., Perrier, A., Pereira, L.S., 1994b. An update for the calculation of reference evapotranspiration. ICID Bull. 43 (2), 35–92]. Measures of soil water loss for winter wheat, maize and peaches were compared with scheduling model predictions. Predicted values of cumulative actual water use were comparable for the two ET equations when a soil water stress function was applied. However, the new PM equation provided slightly higher model efficiency, when used with a peak crop coefficient of 1.25 for maize. A peak value of 1.25 also appeared appropriate for wheat, though the evidence was less strong. Inclusion of the slow mobile water concept slightly improved agreement between measured and predicted soil water changes for the maize and peaches. For peaches, the revised PM equation provided minimum values of root mean square error (R.M.S.E.) and bias, when combined with a slow mobile water representation and using a peak crop coefficient of 0.75.     

昭苏县夏特乡达甫乎尔村发展农机合作社案例

文中介绍了昭苏县夏特乡达普尔村农机合作社发展历程,存在的问题及具体改进措施。     

旱作滴灌铺膜播种农机化技术集成与应用

为解决因水资源缺乏导致的粮食减产问题,开原市大力推广旱作滴灌铺膜播种农机化技术。详细介绍该技术的主要内容、关键环节及培训情况,并综合分析该技术的经济效益、社会效益和生态效益,为该技术在开原市推广应用提供有益借鉴。     

我国农村人畜饮水现状、问题及其对策

目前,我国农村普遍存在着人畜饮水困难,这是历史遗留下的严重问题之一。文章对农村人畜饮水困难的地区分布特点进行了阐述,并从自然、社会和人类活动等方面出发,分析了农村人畜饮水困难的原因;总结了人畜饮水工作的基本经验;指出了存在的主要问题;提出了今后10年我国农村人畜饮水工作目标和解决问题的措施。