With the increasing precision of guidance,the impact of autopilot dynamic characteristics and target maneuvering abilities on precision guidance is becoming more and more significant.In order to reduce or even elimina...With the increasing precision of guidance,the impact of autopilot dynamic characteristics and target maneuvering abilities on precision guidance is becoming more and more significant.In order to reduce or even eliminate the autopilot dynamic operation and the target maneuvering influence,this paper suggests a guidance system model involving a novel integral sliding mode guidance law(ISMGL).The method utilizes the dynamic characteristics and the impact angle,combined with a sliding mode surface scheme that includes the desired line-ofsight angle,line-of-sight angular rate,and second-order differential of the angular line-of-sight.At the same time,the evaluation scenario considere the target maneuvering in the system as the external disturbance,and the non-homogeneous disturbance observer estimate the target maneuvering as a compensation of the guidance command.The proposed system’s stability is proven based on the Lyapunov stability criterion.The simulations reveale that ISMGL effectively intercepted large maneuvering targets and present a smaller miss-distance compared with traditional linear sliding mode guidance laws and trajectory shaping guidance laws.Furthermore,ISMGL has a more accurate impact angle and fast convergence speed.展开更多
Nitrogen(N)is unevenly distributed throughout the soil and plant roots proliferate in N-rich soil patches.However,the relationship between the root response to localized N supply and maize N uptake efficiency among di...Nitrogen(N)is unevenly distributed throughout the soil and plant roots proliferate in N-rich soil patches.However,the relationship between the root response to localized N supply and maize N uptake efficiency among different genotypes is unclear.In this study,four maize varieties were evaluated to explore genotypic differences in the root response to local N application in relation to N uptake.A split-root system was established for hydroponically-grown plants and two methods of local N application(local banding and local dotting)were examined in the field.Genotypic differences in the root length response to N were highly correlated between the hydroponic and field conditions(r>0.99).Genotypes showing high response to N,ZD958,XY335 and XF32D22,showed 50‒63%longer lateral root length and 36‒53%greater root biomass in N-rich regions under hydroponic conditions,while the LY13 genotype did not respond to N.Under field conditions,the root length of the high-response genotypes was found to increase by 66‒75%at 40‒60 cm soil depth,while LY13 showed smaller changes in root length.In addition,local N application increased N uptake at the post-silking stage by 16‒88%in the high-response genotypes and increased the grain yield of ZD958 by 10‒12%.Moreover,yield was positively correlated with root length at 40‒60 cm soil depth(r=0.39).We conclude that local fertilization should be used for high-response genotypes,which can be rapidly identified at the seedling stage,and selection for“local-N responsive roots”can be a promising trait in maize breeding for high nitrogen uptake efficiency.展开更多
文摘With the increasing precision of guidance,the impact of autopilot dynamic characteristics and target maneuvering abilities on precision guidance is becoming more and more significant.In order to reduce or even eliminate the autopilot dynamic operation and the target maneuvering influence,this paper suggests a guidance system model involving a novel integral sliding mode guidance law(ISMGL).The method utilizes the dynamic characteristics and the impact angle,combined with a sliding mode surface scheme that includes the desired line-ofsight angle,line-of-sight angular rate,and second-order differential of the angular line-of-sight.At the same time,the evaluation scenario considere the target maneuvering in the system as the external disturbance,and the non-homogeneous disturbance observer estimate the target maneuvering as a compensation of the guidance command.The proposed system’s stability is proven based on the Lyapunov stability criterion.The simulations reveale that ISMGL effectively intercepted large maneuvering targets and present a smaller miss-distance compared with traditional linear sliding mode guidance laws and trajectory shaping guidance laws.Furthermore,ISMGL has a more accurate impact angle and fast convergence speed.
基金supported by the Hainan Provincial Natural Science Foundation of China(321CXTD443)the National Natural Science Foundation of China(31972485 and 31971948).
文摘Nitrogen(N)is unevenly distributed throughout the soil and plant roots proliferate in N-rich soil patches.However,the relationship between the root response to localized N supply and maize N uptake efficiency among different genotypes is unclear.In this study,four maize varieties were evaluated to explore genotypic differences in the root response to local N application in relation to N uptake.A split-root system was established for hydroponically-grown plants and two methods of local N application(local banding and local dotting)were examined in the field.Genotypic differences in the root length response to N were highly correlated between the hydroponic and field conditions(r>0.99).Genotypes showing high response to N,ZD958,XY335 and XF32D22,showed 50‒63%longer lateral root length and 36‒53%greater root biomass in N-rich regions under hydroponic conditions,while the LY13 genotype did not respond to N.Under field conditions,the root length of the high-response genotypes was found to increase by 66‒75%at 40‒60 cm soil depth,while LY13 showed smaller changes in root length.In addition,local N application increased N uptake at the post-silking stage by 16‒88%in the high-response genotypes and increased the grain yield of ZD958 by 10‒12%.Moreover,yield was positively correlated with root length at 40‒60 cm soil depth(r=0.39).We conclude that local fertilization should be used for high-response genotypes,which can be rapidly identified at the seedling stage,and selection for“local-N responsive roots”can be a promising trait in maize breeding for high nitrogen uptake efficiency.
