Alternating current electroluminescence(ACEL)shows great potential in lighting,display and intelligent skin.Herein,the ACEL properties of Pr3þ-doped Ba0$85Ca0$15Ti0$90Zr0$10O3 ceramic and its PDMS-based composite...Alternating current electroluminescence(ACEL)shows great potential in lighting,display and intelligent skin.Herein,the ACEL properties of Pr3þ-doped Ba0$85Ca0$15Ti0$90Zr0$10O3 ceramic and its PDMS-based composite have been investigated.Intense red EL emission was obtained in the ceramic sample whereas blue EL emission of Pr3þwas observed for the first time in the composite counterpart.The red EL emission should be attributed to the impact of hot electrons driven by the large piezoelectric electric field.Owing to the cross-relaxations through the 4f5d levels and Pr-to-metal charge transfer state,the 3 PJ emissions were completely quenched,and thus leading to an enhancement in red emission.However,external E field induced a large local piezoelectric deformation of the ceramic particles embedded in the PDMS matrix,which in turn caused a bending of CB and then a downwards shift of the 4f5d levels from the CB.Hence the cross-relaxations were hindered,and the blue EL emission was observed in the composites.The results would attract attention of functional materials studies and expand our understanding of such facile structure and oxide EL devices to facilitate their use in integral part of flexible device systems.展开更多
In this work, we investigate the tracking control problem of asymmetrical underactuated surface vessels with parameter uncertainties. The tracking error model is first derived via appropriate coordinate transformation...In this work, we investigate the tracking control problem of asymmetrical underactuated surface vessels with parameter uncertainties. The tracking error model is first derived via appropriate coordinate transformations, and is considered as a cascade structure composed of two subsystems. The Lyapunov redesign approach is employed to construct the control laws separately to stabilize the two subsystems with unknown model parameters. The cascade system theory is applied to prove the global uniform asymptotic convergence of the state trajectory to the reference one provided the desired yaw velocity is not vanishing. The effectiveness of the proposed control laws is verified by simulation examples.展开更多
基金funded by Research Grant Council of Hong Kong Special Administrative Region(PolyU 152236/17E)Program for Chang Jiang Scholars and Innovative Research Teams in Universities(No.IRT_17R40)+2 种基金Science and Technology Program of Guangzhou(No.201904020007)China Postdoctoral Science Foundation(2020M672667)funded by Guangdong Provincial Key Laboratory of Optical Information Materials and Technology(2017B030301007).
文摘Alternating current electroluminescence(ACEL)shows great potential in lighting,display and intelligent skin.Herein,the ACEL properties of Pr3þ-doped Ba0$85Ca0$15Ti0$90Zr0$10O3 ceramic and its PDMS-based composite have been investigated.Intense red EL emission was obtained in the ceramic sample whereas blue EL emission of Pr3þwas observed for the first time in the composite counterpart.The red EL emission should be attributed to the impact of hot electrons driven by the large piezoelectric electric field.Owing to the cross-relaxations through the 4f5d levels and Pr-to-metal charge transfer state,the 3 PJ emissions were completely quenched,and thus leading to an enhancement in red emission.However,external E field induced a large local piezoelectric deformation of the ceramic particles embedded in the PDMS matrix,which in turn caused a bending of CB and then a downwards shift of the 4f5d levels from the CB.Hence the cross-relaxations were hindered,and the blue EL emission was observed in the composites.The results would attract attention of functional materials studies and expand our understanding of such facile structure and oxide EL devices to facilitate their use in integral part of flexible device systems.
基金supported by National Science and Technology Major Project(No.2012CB821202)the Beijing Natural Science Foundation(Nos.4122043,4112034)the National Natural Science Foundation of China(Nos.60874012,61174057)
文摘In this work, we investigate the tracking control problem of asymmetrical underactuated surface vessels with parameter uncertainties. The tracking error model is first derived via appropriate coordinate transformations, and is considered as a cascade structure composed of two subsystems. The Lyapunov redesign approach is employed to construct the control laws separately to stabilize the two subsystems with unknown model parameters. The cascade system theory is applied to prove the global uniform asymptotic convergence of the state trajectory to the reference one provided the desired yaw velocity is not vanishing. The effectiveness of the proposed control laws is verified by simulation examples.
