The formation maintenance of multiple unmanned aerial vehicles(UAVs)based on proximity behavior is explored in this study.Individual decision-making is conducted according to the expected UAV formation structure and t...The formation maintenance of multiple unmanned aerial vehicles(UAVs)based on proximity behavior is explored in this study.Individual decision-making is conducted according to the expected UAV formation structure and the position,velocity,and attitude information of other UAVs in the azimuth area.This resolves problems wherein nodes are necessarily strongly connected and communication is strictly consistent under the traditional distributed formation control method.An adaptive distributed formation flight strategy is established for multiple UAVs by exploiting proximity behavior observations,which remedies the poor flexibility in distributed formation.This technique ensures consistent position and attitude among UAVs.In the proposed method,the azimuth area relative to the UAV itself is established to capture the state information of proximal UAVs.The dependency degree factor is introduced to state update equation based on proximity behavior.Finally,the formation position,speed,and attitude errors are used to form an adaptive dynamic adjustment strategy.Simulations are conducted to demonstrate the effectiveness and robustness of the theoretical results,thus validating the effectiveness of the proposed method.展开更多
A barotropic channel model in β-plane is used to study the effect of topographic forcing on the formation and maintenance of blocking. The approximate analytical solution of potential vorticity equation can show the ...A barotropic channel model in β-plane is used to study the effect of topographic forcing on the formation and maintenance of blocking. The approximate analytical solution of potential vorticity equation can show the main property of the whole process of blocking. It is indicated that the topographic forcing is one of the main factors causing the blocking process. The results suggest that the nonlinear interaction plays a very important role in the stable 'Ω' situation of blocking. The atmospheric circulation with periodic and low-frequency oscillation, perhaps, is partly caused by topographic forcing.展开更多
Maintenance of high performance formation control is important for low Earth orbit(LEO)formation missions of small spacecraft.In this paper,a model of nonlinear relative motion dynamics is built,and then nonlinear and...Maintenance of high performance formation control is important for low Earth orbit(LEO)formation missions of small spacecraft.In this paper,a model of nonlinear relative motion dynamics is built,and then nonlinear and important perturbations affecting the formation configuration,such as J 2 and atmospheric drag,are analyzed as disturbances.Global navigation satellite system based relative positioning with nonlinear filtering is adopted to provide state information associated with the perturbations.By combining disturbance observer based control with H∞state feedback,a composite disturbance attenuation controller is proposed for maintenance of continuous and accurate formation.With consideration of precise control relying on micro thrusters,a composite disturbance attenuation based saturated controller is designed and its stability is proved.Finally,through numerical simulations,we demonstrate that control accuracy is improved after effectively avoiding perturbations and that stabilization can be satisfied using this method.展开更多
Proper social behaviors are essential for survival and success,and deficits in these behaviors are associated with many brain disorders.However,the mechanisms underlying the formation and maintenance of social memory ...Proper social behaviors are essential for survival and success,and deficits in these behaviors are associated with many brain disorders.However,the mechanisms underlying the formation and maintenance of social memory remain poorly understood.In this study,we demonstrate that social interaction with unfamiliar mouse inducesα-andγ-secretase-dependent proteolysis of Neuroligin 1(NLG1)in the ventral hippocampus(vHPC).The intracellular hydrolysate fragment,NLG1-CTD,regulates synaptic plasticity,spine strengthening,and the maintenance of social memory through its PDZ binding domain(PBD)and the cofilin signaling pathway.Bothγ-secretase inhibition and deletion of the secretase recognition site on NLG1 prevent cofilin phosphorylation and impair the maintenance of social memory by inhibiting the production of NLG1-CTD.Injection of the Tat-PBD peptide into the vHPC inhibits cofilin activity and rescues deficits in social memory maintenance in mouse models.Additionally,our findings indicate that deficits in maintaining memory for sequentially presented social objects within a short temporal interval may be associated with insufficient levels of NLG1-CTD.Supplementation of Tat-PBD into the vHPC promotes maturation of dendritic spines and restores the maintenance of memory for the second social object.We also discovered that NLG1-CTD/PBD may play a role in maintaining novel object recognition memory.In summary,this work uncovers a novel mechanism that links extracellular and intracellular signal transduction processes to synaptic remodeling during learning and memory maintenance,providing a systematic perspective that connects memory formation,maintenance,and synaptic structural and functional plasticity.展开更多
文摘The formation maintenance of multiple unmanned aerial vehicles(UAVs)based on proximity behavior is explored in this study.Individual decision-making is conducted according to the expected UAV formation structure and the position,velocity,and attitude information of other UAVs in the azimuth area.This resolves problems wherein nodes are necessarily strongly connected and communication is strictly consistent under the traditional distributed formation control method.An adaptive distributed formation flight strategy is established for multiple UAVs by exploiting proximity behavior observations,which remedies the poor flexibility in distributed formation.This technique ensures consistent position and attitude among UAVs.In the proposed method,the azimuth area relative to the UAV itself is established to capture the state information of proximal UAVs.The dependency degree factor is introduced to state update equation based on proximity behavior.Finally,the formation position,speed,and attitude errors are used to form an adaptive dynamic adjustment strategy.Simulations are conducted to demonstrate the effectiveness and robustness of the theoretical results,thus validating the effectiveness of the proposed method.
文摘A barotropic channel model in β-plane is used to study the effect of topographic forcing on the formation and maintenance of blocking. The approximate analytical solution of potential vorticity equation can show the main property of the whole process of blocking. It is indicated that the topographic forcing is one of the main factors causing the blocking process. The results suggest that the nonlinear interaction plays a very important role in the stable 'Ω' situation of blocking. The atmospheric circulation with periodic and low-frequency oscillation, perhaps, is partly caused by topographic forcing.
基金supported by the National High-Tech R&D Program(863)of China(No.2008AA12A216)the National Basic Research Program(973)of China(No.2009CB72400101C)
文摘Maintenance of high performance formation control is important for low Earth orbit(LEO)formation missions of small spacecraft.In this paper,a model of nonlinear relative motion dynamics is built,and then nonlinear and important perturbations affecting the formation configuration,such as J 2 and atmospheric drag,are analyzed as disturbances.Global navigation satellite system based relative positioning with nonlinear filtering is adopted to provide state information associated with the perturbations.By combining disturbance observer based control with H∞state feedback,a composite disturbance attenuation controller is proposed for maintenance of continuous and accurate formation.With consideration of precise control relying on micro thrusters,a composite disturbance attenuation based saturated controller is designed and its stability is proved.Finally,through numerical simulations,we demonstrate that control accuracy is improved after effectively avoiding perturbations and that stabilization can be satisfied using this method.
基金supported by grants from STI2030-Major Projects(2022ZD0205900,A.L.,2021ZD0204000,W.X.and A.L.)Natural Science Foundation of Jiangsu Province(BK20211561,A.L.)Natural Science Foundation of China(NSFC 32571220,A.L.)。
文摘Proper social behaviors are essential for survival and success,and deficits in these behaviors are associated with many brain disorders.However,the mechanisms underlying the formation and maintenance of social memory remain poorly understood.In this study,we demonstrate that social interaction with unfamiliar mouse inducesα-andγ-secretase-dependent proteolysis of Neuroligin 1(NLG1)in the ventral hippocampus(vHPC).The intracellular hydrolysate fragment,NLG1-CTD,regulates synaptic plasticity,spine strengthening,and the maintenance of social memory through its PDZ binding domain(PBD)and the cofilin signaling pathway.Bothγ-secretase inhibition and deletion of the secretase recognition site on NLG1 prevent cofilin phosphorylation and impair the maintenance of social memory by inhibiting the production of NLG1-CTD.Injection of the Tat-PBD peptide into the vHPC inhibits cofilin activity and rescues deficits in social memory maintenance in mouse models.Additionally,our findings indicate that deficits in maintaining memory for sequentially presented social objects within a short temporal interval may be associated with insufficient levels of NLG1-CTD.Supplementation of Tat-PBD into the vHPC promotes maturation of dendritic spines and restores the maintenance of memory for the second social object.We also discovered that NLG1-CTD/PBD may play a role in maintaining novel object recognition memory.In summary,this work uncovers a novel mechanism that links extracellular and intracellular signal transduction processes to synaptic remodeling during learning and memory maintenance,providing a systematic perspective that connects memory formation,maintenance,and synaptic structural and functional plasticity.
