Quasi-2D perovskites have attracted tremendous interest for application as lightemission layers in light-emitting diodes(LEDs).However,the heterogeneous n phase and non-uniform distribution still severely limit the fu...Quasi-2D perovskites have attracted tremendous interest for application as lightemission layers in light-emitting diodes(LEDs).However,the heterogeneous n phase and non-uniform distribution still severely limit the further development of quasi-2D perovskite LEDs(Pero-LEDs).Meanwhile,the increased defect density caused by the reduced dimension and grain size induces non-radiative recombination and further deteriorates the device performance.Here,we found that a series of molecules containing phosphoryl chloride functional groups have noticeable enhancement effects on the device performance of quasi-2D Pero-LEDs.Then,we studied the modification mechanism by focusing on the bis(2-oxo-3-oxazolidinyl)phosphinic chloride(BOPCl).It is concluded that the BOPCl can not only regulate the phase distribution by decreasing the crystallization rate but also remain in the grain boundaries and passivate the defects.As a result,the corresponding quasi-2D Pero-LEDs obtained a maximum external quantum efficiency(EQE_(max))of 20.82%and an average EQE(EQE_(ave))of around 20%on the optimal 50 devices,proving excellent reproducibility.Our work provides a new selection of molecular types for regulating the crystallization and passivating the defects of quasi-2D perovskite films.展开更多
Based on the 2D horizontal plane numerical model, a quasi-3D numerical model is established for coastal regions of shallow water. The characteristics of this model are that the velocity profiles;can be obtained at the...Based on the 2D horizontal plane numerical model, a quasi-3D numerical model is established for coastal regions of shallow water. The characteristics of this model are that the velocity profiles;can be obtained at the same time when the equations of the value of difference between the horizontal current velocity and its depth-averaged velocity in the vertical direction are solved and the results obtained are consistent with the results of the 2D, model. The circulating flow in the rectangular area induced by wind is simulated and applied to the tidal flow field of the radial sandbanks in the South Yellow Sea. The computational results from this quasi-3D model are in good agreement with analytical results and observed data. The solution of the finite difference equations has been found to be stable, and the model is simple, effective and practical.展开更多
This paper presents the field oriented vector control scheme for synchronous reluctance motor (SRM) drives, where current controller followed by hysteresis comparator is used. The test motor has a star-connected wound...This paper presents the field oriented vector control scheme for synchronous reluctance motor (SRM) drives, where current controller followed by hysteresis comparator is used. The test motor has a star-connected wound stator and a segmental rotor of the multiple barrier type with an external incremental encoder to sense rotor position. The magnetic characteristics of this motor are described using 2D finite element method, which is used firstly for rotor design of SRM. The field oriented vector control, that regulates the speed of the SRM, is provided by a quadrature axis current command developed by the speed controller. The simulation includes all realistic components of the system. This enables the calculation of currents and voltages in different parts of the voltage source inverter (VSI) and motor under transient and steady state conditions. Implementation has been done in MATLAB/Simulink. A study of hysteresis control scheme associated with current controllers has been made. Experimental results of the SRM control using TMS320F24X DSP board are presented. The speed of the SRM is successfully controlled in the constant torque region. Experimental results of closed loop speed control of the SRM are given to verify the proposed scheme.展开更多
基金supported by the National Natural Science Foundation of China(U21A2078)Natural Science Foundation of Fujian Province(2020J06021,2019J01057,and 2020J01064)Scientific Research Funds of Huaqiao University.
文摘Quasi-2D perovskites have attracted tremendous interest for application as lightemission layers in light-emitting diodes(LEDs).However,the heterogeneous n phase and non-uniform distribution still severely limit the further development of quasi-2D perovskite LEDs(Pero-LEDs).Meanwhile,the increased defect density caused by the reduced dimension and grain size induces non-radiative recombination and further deteriorates the device performance.Here,we found that a series of molecules containing phosphoryl chloride functional groups have noticeable enhancement effects on the device performance of quasi-2D Pero-LEDs.Then,we studied the modification mechanism by focusing on the bis(2-oxo-3-oxazolidinyl)phosphinic chloride(BOPCl).It is concluded that the BOPCl can not only regulate the phase distribution by decreasing the crystallization rate but also remain in the grain boundaries and passivate the defects.As a result,the corresponding quasi-2D Pero-LEDs obtained a maximum external quantum efficiency(EQE_(max))of 20.82%and an average EQE(EQE_(ave))of around 20%on the optimal 50 devices,proving excellent reproducibility.Our work provides a new selection of molecular types for regulating the crystallization and passivating the defects of quasi-2D perovskite films.
基金National Natural Science Foundation of China(Grant No.49236120)
文摘Based on the 2D horizontal plane numerical model, a quasi-3D numerical model is established for coastal regions of shallow water. The characteristics of this model are that the velocity profiles;can be obtained at the same time when the equations of the value of difference between the horizontal current velocity and its depth-averaged velocity in the vertical direction are solved and the results obtained are consistent with the results of the 2D, model. The circulating flow in the rectangular area induced by wind is simulated and applied to the tidal flow field of the radial sandbanks in the South Yellow Sea. The computational results from this quasi-3D model are in good agreement with analytical results and observed data. The solution of the finite difference equations has been found to be stable, and the model is simple, effective and practical.
文摘This paper presents the field oriented vector control scheme for synchronous reluctance motor (SRM) drives, where current controller followed by hysteresis comparator is used. The test motor has a star-connected wound stator and a segmental rotor of the multiple barrier type with an external incremental encoder to sense rotor position. The magnetic characteristics of this motor are described using 2D finite element method, which is used firstly for rotor design of SRM. The field oriented vector control, that regulates the speed of the SRM, is provided by a quadrature axis current command developed by the speed controller. The simulation includes all realistic components of the system. This enables the calculation of currents and voltages in different parts of the voltage source inverter (VSI) and motor under transient and steady state conditions. Implementation has been done in MATLAB/Simulink. A study of hysteresis control scheme associated with current controllers has been made. Experimental results of the SRM control using TMS320F24X DSP board are presented. The speed of the SRM is successfully controlled in the constant torque region. Experimental results of closed loop speed control of the SRM are given to verify the proposed scheme.
