Improving crop water productivity is necessary for ensuring food security. To quantify the water utilization in grain production from multiple perspectives, gross inflow water productivity(WPg), generalized agricultur...Improving crop water productivity is necessary for ensuring food security. To quantify the water utilization in grain production from multiple perspectives, gross inflow water productivity(WPg), generalized agricultural water productivity(WPa), evapotranspiration water productivity(WPET) and irrigation water productivity(WPI) were examined in this study. This paper calculated and analyzed the temporal and spatial variation in these water productivity(WP) indices in the irrigated land of Heilongjiang Province. The results showed that almost all of the municipal WP indices increased from 2007 to 2015. The four indices showed large differences in scientific connotation and numerical performance, and their degrees of spatial variation were ranked as WPI>WPa>WPg>WPET. The spatial patterns of WP indices in different years were similar; the central and southern regions on the Songnen Plain and the eastern region had high WP values, while those of the northern region were low. Each WP index was used to evaluate the relationship between the input of water resources and the output of grain between different regions. Most cities had the potential to improve WP by reducing the input of irrigation water. Furthermore, the results provided recommendations to decision makers to plan for efficient use of water resources in different cities.展开更多
Frequency-invariant beamformer （FIB） design is a key issue in wideband array signal processing. To use commonly wideband linear array with tapped delay line （TDL） structure and complex weights, the FIB design is p...Frequency-invariant beamformer （FIB） design is a key issue in wideband array signal processing. To use commonly wideband linear array with tapped delay line （TDL） structure and complex weights, the FIB design is provided according to the rule of minimizing the sidelobe level of the beampattern at the reference frequency while keeping the distortionless response constraint in the mainlobe direction at the reference frequency, the norm constraint of the weight vector and the amplitude constraint of the averaged spatial response variation （SRV）. This kind of beamformer design problem can be solved with the interior-point method after being converted to the form of standard second order cone programming （SOCP）. The computer simulations are presented which illustrate the effectiveness of our FIB design method for the wideband linear array with TDL structure and complex weights.展开更多
基金Supported by National Natural Science Foundation of China(51479032)National Key R&D Plan(2017YFC0406002)
文摘Improving crop water productivity is necessary for ensuring food security. To quantify the water utilization in grain production from multiple perspectives, gross inflow water productivity(WPg), generalized agricultural water productivity(WPa), evapotranspiration water productivity(WPET) and irrigation water productivity(WPI) were examined in this study. This paper calculated and analyzed the temporal and spatial variation in these water productivity(WP) indices in the irrigated land of Heilongjiang Province. The results showed that almost all of the municipal WP indices increased from 2007 to 2015. The four indices showed large differences in scientific connotation and numerical performance, and their degrees of spatial variation were ranked as WPI>WPa>WPg>WPET. The spatial patterns of WP indices in different years were similar; the central and southern regions on the Songnen Plain and the eastern region had high WP values, while those of the northern region were low. Each WP index was used to evaluate the relationship between the input of water resources and the output of grain between different regions. Most cities had the potential to improve WP by reducing the input of irrigation water. Furthermore, the results provided recommendations to decision makers to plan for efficient use of water resources in different cities.
基金supported by the President Award of Chinese Academy of Sciences (O729031511)
文摘Frequency-invariant beamformer （FIB） design is a key issue in wideband array signal processing. To use commonly wideband linear array with tapped delay line （TDL） structure and complex weights, the FIB design is provided according to the rule of minimizing the sidelobe level of the beampattern at the reference frequency while keeping the distortionless response constraint in the mainlobe direction at the reference frequency, the norm constraint of the weight vector and the amplitude constraint of the averaged spatial response variation （SRV）. This kind of beamformer design problem can be solved with the interior-point method after being converted to the form of standard second order cone programming （SOCP）. The computer simulations are presented which illustrate the effectiveness of our FIB design method for the wideband linear array with TDL structure and complex weights.
