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91.
92.
灌区存在大量过流能力0.1m3/s以下的小型取水口,往往由于闸门设施简陋、管理粗放、缺少监控而产生严重的水资源浪费。农业水价综合改革要求计量用水到户,传统的小型取水口闸难以满足这一要求。本文基于江西锦北灌区小型取水口的管理现状和问题,讨论分析国内外现代化自动控制闸的适用性,提出自主研发阀式远程自动控制闸的方案。该闸型技术功能强而成本低、易于量产,可集成自动量水、远程控制与视频监控的一体化自动监控系统,便于安装与维护,运行管理效率高,在小型取水口大面积自动化改造方面优势明显,具有推广价值。 相似文献
93.
Luz‐Stella Artajo Maria‐Paz Romero Maria‐Jesús Tovar Maria‐Jos Motilva 《European Journal of Lipid Science and Technology》2006,108(1):19-27
The main objective of this research was to determine the extent to which irrigation practices affect the partitioning of phenolic compounds between olive paste, pomace, olive oil and wastewater. The current paper also aimed to study the effect of technological natural micro‐talc (NMT) addition during the oil extraction process on the partitioning of the phenolic compounds between solid and liquid phases. The results obtained in this study showed that irrigation applied to olive trees let to a considerable decrease in the phenol content of the olive paste. The water status of the trees affected the phenol synthesis in the olive fruit, and consequently the phenol content of the olive paste, more than the partitioning of the phenolic compounds during the olive oil extraction process. The most remarkable point of the phenol partitioning was related to the simple phenols. While in the samples from non‐irrigated trees the greater proportion of these phenols partitioned into the pomace, in samples from irrigated trees most of them were lost in the wastewater. After comparison of the results obtained from the experiments with and without NMT addition, it was concluded that the use of that co‐adjuvant did not significantly alter either the phenolic profile of the oil phase obtained or the content of the individual phenolic compounds. 相似文献
94.
Morteza N. Orang J. Scott Matyac Richard L. Snyder 《Canadian Metallurgical Quarterly》2008,134(1):96-100
Reliable information on irrigation methods is important for determining agricultural water demand trends. Therefore, a study was conducted during 2002 to collect information on irrigation methods that were used by growers to irrigate their crops in 2001. The results were compared to earlier surveys to assess trends in cropping and irrigation methods. A one-page questionnaire was developed to collect information on irrigated land by crop and irrigation methods. The questionnaire was mailed to 10,000 growers in California that were randomly selected from a list of 58,000 growers by the California Department of Food and Agriculture, excluding rice, dry-land, and livestock producers. From 1972 to 2002, the area planted has increased from 15 to 31% for orchards and from 6 to 16% for vineyards. The area planted to vegetables has remained relatively static, while that planted to field crops has declined from 67 to 42% of the irrigated area. The land irrigated by low-volume (drip and microsprinkler) irrigation has increased by about 33%, while the amount of land irrigated by surface methods has decreased by about 31%. Sprinkler usage has decreased in orchards and vineyards, but it has increased in vegetable crops. 相似文献
95.
Optimal Design of Pressurized Irrigation Subunit 总被引:1,自引:0,他引:1
Ravindra V. Kale Rajesh P. Singh Pooran S. Mahar 《Canadian Metallurgical Quarterly》2008,134(2):137-146
A linear programming (LP) model is presented for optimal design of the pressurized irrigation system subunit. The objective function of the LP is to minimize the equivalent annual fixed cost of pipe network of the irrigation system and its annual operating energy cost. The hydraulic characteristics in the irrigation subunit are ensured by using the length, energy conservation, and pressure head constraints. The input data are the system layout, segment-wise cost and hydraulic gradients in all the alternative pipe diameters, and energy cost per unit head of pumping water through the pipeline network. The output data are: segment-wise lengths of different diameters, operating inlet pressure head, and equivalent annual cost of the pipeline network. The explicit optimal design is demonstrated with design examples on lateral and submain or manifold of pressurized irrigation systems. The effect of the equations for friction head loss calculation on optimization procedure is investigated through the design example for microirrigation manifold. The performance evaluation of the proposed model in comparison with the analytical methods, graphical methods, numerical solutions, and dynamic programming optimization model reveals the good performance of the proposed model. The verification of operating inlet pressure head obtained by the proposed model with accurate numerical step-by-step method suggested that it is mostly accurate. 相似文献
96.
97.
本文介绍了在研建流溪河灌区工程渠首枢纽计算机监控系统过程中开发的提高系统可靠性的几项关键技术:现场总线技术、完备冷冗余技术、故障诊断技术。 相似文献
98.
Miscanthus biomass yield can be limited by poor rhizome establishment and this is linked to rhizome age and storage conditions prior to planting. To avoid poor establishment, best practice recommends field planting directly after rhizome division. Operations avoiding rhizome storage, and utilising favourable climatic conditions at planting, may be climatologically and logistically challenging when large areas are planted at high rhizome densities. Our aim is to evaluate storage regimes to maintain rhizome viability and maximise establishment when planted under optimal conditions. To achieve this we have compared differences in site pre-planting management (level of soil cultivation) strategies, along with post-planting treatments (irrigation and soil mulching with compost), against differences in storage regime (temperature) and duration. The results from a rhizome establishment bioassay showed viability at lifting in early March was high, while cold storage of rhizomes had no negative influence on viability and growth. There were no negative impacts of storage temperature on rhizome mineral or carbohydrate concentrations. Increases in air temperature enhanced rhizome and culm final biomass and rate of establishment. Application of irrigation, or compost mulch, to field rhizome plantings improved establishment increasing soil moisture levels in early May through August. In conclusion, cold storage of rhizomes is achievable and effective in maintaining rhizome viability and can be used to extend the planting time. Soil moisture and application of supplementary irrigation was important during establishment. Also important was the avoidance of weed competition. Achieving the most appropriate conditions for optimal establishment will be critical in regions where spring/summer rainfall is restrictive. 相似文献
99.
To sustain productive irrigated agriculture with limited water resources requires a high water use efficiency. This can be achieved by the precise scheduling of deficit irrigation systems taking into account the crops’ response to water stress at different stages of plant growth. Particularly in the light of climate change with rising population numbers and increasing water scarcity, an optimal solution for this task is of paramount importance. We solve the corresponding complex multidimensional and nonlinear optimization problem, i.e., finding the ideal schedule for maximum crop yield with a given water volume by a well tailored approach which offers straightforward application facilities. A global optimization technique allows, together with physically based modeling, for the risk assessment in yield reduction considering different sources of uncertainty (e.g., climate, soil conditions, and management). A new stochastic framework for decision support is developed which aims at optimal climate change adaption strategies in irrigation. It consists of: (1) a weather generator for simulating regional impacts of climate change; (2) a tailor-made evolutionary optimization algorithm for optimal irrigation scheduling with limited water supply; and (3) mechanistic models for rigorously simulating water transport and crop growth. The result, namely, stochastic crop-water production functions, allows to assess the impact of climate variability on potential yield and thus provides a valuable tool for estimating minimum water demands for irrigation in water resources planning and management, assisting furthermore in generating maps of yield uncertainty for specific crops and specific agricultural areas. The tool is successfully applied at an experimental site in southern France. The impacts of predicted climate variability on maize are discussed. 相似文献
100.
Ali R. Vatankhah 《Canadian Metallurgical Quarterly》2011,137(9):620-623
Control of irrigation canals usually consists of control of water levels upstream from regulators or check structures. Regulators provide the necessary head to offtakes. Generally, influence factor is used to express the extension of the backwater curve effect within the controlled reach. This factor shows how a change in water depth exercised by a regulator can influence the water surface profile along an irrigation canal. No direct equation is available in the technical literature up until now for calculating this factor on the basis of the steady gradually varied flow theorem. In current research, using the steady gradually varied flow equation for a prismatic canal, an elegant algebraic equation for this factor is derived. Control of water levels upstream from regulators is an important application of this equation in irrigation networks. 相似文献