Using a crop-water-salinity production function and a soil-water-salinity dynamic model, optimal irrigation scheduling was developed to maximize net return per irrigated area. Plot and field experiments were used to o...Using a crop-water-salinity production function and a soil-water-salinity dynamic model, optimal irrigation scheduling was developed to maximize net return per irrigated area. Plot and field experiments were used to obtain the crop water sensitivity index, the salinity sensitivity index, and other parameters. Using data collected during 35 years to calculate the 10-day mean precipitation and evaporation, the variation in soil salinity concentrations and in the yields of winter wheat and cotton were simulated for 49 irrigation scheduling that were combined from 7 irrigation schemes over 3 irrigation dates and 7 salinity concentrations of saline irrigation water (fresh water and 6 levels of saline water). Comparison of predicted results with irrigation data obtained from a large area of the field showed that the model was valid and reliable. Based on the analysis of the investment cost of the irrigation that employed deep tube wells or shallow tube wells, a saline water irrigation schedule and a corresponding strategy for groundwater development and utilization were proposed. For wheat or cotton, if the salinity concentration was higher than 7.0 g L-1 in groundwater, irrigation was needed with only fresh water; if about 5.0 g L-1, irrigation was required twice with fresh water and once with saline water; and if not higher than 3.0 g L-1, irrigation could be solely with saline water.展开更多
为了提高拓展移相控制的双有源桥DAB(dual active bridge)DC-DC变换器的电压动态响应性能,降低系统的电流应力,利用使电流应力最小的优化相移比与输出电压之间的关系,提出了一种将电压动态矩阵控制DMC(dynamic matrix control)算法与变...为了提高拓展移相控制的双有源桥DAB(dual active bridge)DC-DC变换器的电压动态响应性能,降低系统的电流应力,利用使电流应力最小的优化相移比与输出电压之间的关系,提出了一种将电压动态矩阵控制DMC(dynamic matrix control)算法与变换器电流应力优化方法相结合的控制算法,并从预测模型、滚动优化和反馈校正3个环节详细介绍了DAB的DMC电压预测控制的具体实现过程。最后,将所提控制方法与电压闭环PI控制的拓展移相电流应力优化算法进行了仿真比较。仿真结果表明:该方法不仅减小了电流应力,而且在变换器启动阶段、输入电压突变和负载突变时大大改善了变换器的电压动态响应性能。展开更多
基金Project supported by the National Natural Science Foundation of China (Nos. 50339030 and 90202001).
文摘Using a crop-water-salinity production function and a soil-water-salinity dynamic model, optimal irrigation scheduling was developed to maximize net return per irrigated area. Plot and field experiments were used to obtain the crop water sensitivity index, the salinity sensitivity index, and other parameters. Using data collected during 35 years to calculate the 10-day mean precipitation and evaporation, the variation in soil salinity concentrations and in the yields of winter wheat and cotton were simulated for 49 irrigation scheduling that were combined from 7 irrigation schemes over 3 irrigation dates and 7 salinity concentrations of saline irrigation water (fresh water and 6 levels of saline water). Comparison of predicted results with irrigation data obtained from a large area of the field showed that the model was valid and reliable. Based on the analysis of the investment cost of the irrigation that employed deep tube wells or shallow tube wells, a saline water irrigation schedule and a corresponding strategy for groundwater development and utilization were proposed. For wheat or cotton, if the salinity concentration was higher than 7.0 g L-1 in groundwater, irrigation was needed with only fresh water; if about 5.0 g L-1, irrigation was required twice with fresh water and once with saline water; and if not higher than 3.0 g L-1, irrigation could be solely with saline water.
文摘为了提高拓展移相控制的双有源桥DAB(dual active bridge)DC-DC变换器的电压动态响应性能,降低系统的电流应力,利用使电流应力最小的优化相移比与输出电压之间的关系,提出了一种将电压动态矩阵控制DMC(dynamic matrix control)算法与变换器电流应力优化方法相结合的控制算法,并从预测模型、滚动优化和反馈校正3个环节详细介绍了DAB的DMC电压预测控制的具体实现过程。最后,将所提控制方法与电压闭环PI控制的拓展移相电流应力优化算法进行了仿真比较。仿真结果表明:该方法不仅减小了电流应力,而且在变换器启动阶段、输入电压突变和负载突变时大大改善了变换器的电压动态响应性能。
