This paper reviews the performances of some newly developed reluctance machines with different winding configurations,excitation methods,stator and rotor structures,and slot/pole number combinations.Both the double la...This paper reviews the performances of some newly developed reluctance machines with different winding configurations,excitation methods,stator and rotor structures,and slot/pole number combinations.Both the double layer conventional(DLC-),double layer mutually-coupled(DLMC),single layer conventional(SLC-),and single layer mutually-coupled(SLMC-),as well as fully-pitched(FP)winding configurations have been considered for both rectangular wave and sinewave excitations.Different conduction angles such as unipolar120°elec.,unipolar/bipolar180°elec.,bipolar240°elec.and bipolar360°elec.have been adopted and the most appropriate conduction angles have been obtained for the SRMs with different winding configurations.In addition,with appropriate conduction angles,the 12-slot/14-pole SRMs with modular stator structure is found to produce similar average torque,but lower torque ripple and iron loss when compared to non-modular 12-slot/8-pole SRMs.With sinewave excitation,the doubly salient synchronous reluctance machines with the DLMC winding can produce the highest average torque at high currents and achieve the highest peak efficiency as well.In order to compare with the conventional synchronous reluctance machines(SynRMs)having flux barriers inside the rotor,the appropriate rotor topologies to obtain the maximum average torque have been investigated for different winding configurations and slot/pole number combinations.Furthermore,some prototypes have been built with different winding configurations,stator structures,and slot/pole combinations to validate the predictions.展开更多
The investigations on the dynamies of the PBL have been developed in recent years. Some authors emphasized macro-dynamics and others emphasized micro-structure of the PBL. In this paper, we study and review some main ...The investigations on the dynamies of the PBL have been developed in recent years. Some authors emphasized macro-dynamics and others emphasized micro-structure of the PBL. In this paper, we study and review some main characteristics of the wind field in the PBL from the view point connecting the macro-dynamics and micro-stucture of the PBL, thus providing the physical basis for the further research of the dynamics and the parameterization of the PBL.展开更多
This paper proposed an analytical model which can calculate the effective thermal conductivity (ETC) of a spiral-wound Lithium-ion battery (Li-ion battery). It bases on a two-dimensional energy balance with both radia...This paper proposed an analytical model which can calculate the effective thermal conductivity (ETC) of a spiral-wound Lithium-ion battery (Li-ion battery). It bases on a two-dimensional energy balance with both radial and spiral heat transfer, as well as internal thermal contact resistance (TCR) considered simultaneously and studies the influence of winding layers and winding tension on the ETC. Results show that the analytical data are in good agreement with the numerical results. With the winding layers decreased and the winding tension enhanced, the ETC of Li-ion battery increases gradually. The radial temperature in Li-ion battery is also investigated which demonstrates a relatively higher temperature when considering the internal TCR.展开更多
This study investigates the variation in the stratospheric quasi-zero wind layer(QZWL)over Dunhuang,Gansu Province,China,on 9 August 2020 using sounding observations from the Dunhuang national reference station and th...This study investigates the variation in the stratospheric quasi-zero wind layer(QZWL)over Dunhuang,Gansu Province,China,on 9 August 2020 using sounding observations from the Dunhuang national reference station and the fifth generation of ECMWF atmospheric reanalysis data(ERA5).The QZWL over Dunhuang was located between 18.6 and 20.4 km on 9 August 2020.The South Asian high(SAH)and subtropical westerly jet jointly affected the QZWL.As the SAH retreated westward,the upper-level westerly jet over Dunhuang strengthened,and the jet axis height increased.As a result,the zonal westerly wind was lifted to a higher altitude,and the wind speed of 100–70 hPa increased,raising the QZWL.In addition,the east–west oscillation of the SAH occurred earlier than the adjustment of the QZWL altitude,which can be used as a forecasting indicator for the QZWL.To further explore the mechanism responsible for the QZWL adjustment,the forcing terms in the equations for zonal wind,kinetic energy,and vertical wind shear were analyzed.The results showed that the upper-level geopotential gradient was the basic physical factor forcing the local change in zonal wind and kinetic energy.The change in zonal wind and kinetic energy led to the uplift of the QZWL.The results revealed that the vertical shear of horizontal wind could adequately indicate the stratospheric QZWL location.展开更多
The vertical transport of mass at the top of the boundary layer is considered as a link between the boundary layer and free atmosphere.The adjustment of the wind and pressure fields in the boundary layer is studied un...The vertical transport of mass at the top of the boundary layer is considered as a link between the boundary layer and free atmosphere.The adjustment of the wind and pressure fields in the boundary layer is studied under the consideration of the interaction between the boundary layer and free atmosphere.The vertical motion at the top of the boundary layer is evaluated.The results show that the distinguished differ- ences of the present results from classical Ekman layer do exist and they are discussed in the paper.展开更多
In this paper,under the assumption of neutral and barotropic atmosphere,by means of the analytic solution of motion equation of PBL,the influences of nonstationary process on the internal parameters u_*/A(A is the win...In this paper,under the assumption of neutral and barotropic atmosphere,by means of the analytic solution of motion equation of PBL,the influences of nonstationary process on the internal parameters u_*/A(A is the wind speed at the top of PBL)and ■(the angle between winds near the surface and at the top of PBL)of PBL are investigated in which the wind direction at the top of PBL is a periodic function of time but the wind speed at the top of PBL does not change.The u_*/A increases and ■ decreases when the wind direction at the top of PBL rotates anticlockwise and vice versa.Hence the parameterization of PBL in the large-scale models derived under the stationary condition should be corrected by accounting for the nonstationary process.The similar results are obtained in the numerical solution of the motion equation of PBL.The influences of this nonstationary process on the profiles of the wind in PBL are also analyzed.展开更多
文摘This paper reviews the performances of some newly developed reluctance machines with different winding configurations,excitation methods,stator and rotor structures,and slot/pole number combinations.Both the double layer conventional(DLC-),double layer mutually-coupled(DLMC),single layer conventional(SLC-),and single layer mutually-coupled(SLMC-),as well as fully-pitched(FP)winding configurations have been considered for both rectangular wave and sinewave excitations.Different conduction angles such as unipolar120°elec.,unipolar/bipolar180°elec.,bipolar240°elec.and bipolar360°elec.have been adopted and the most appropriate conduction angles have been obtained for the SRMs with different winding configurations.In addition,with appropriate conduction angles,the 12-slot/14-pole SRMs with modular stator structure is found to produce similar average torque,but lower torque ripple and iron loss when compared to non-modular 12-slot/8-pole SRMs.With sinewave excitation,the doubly salient synchronous reluctance machines with the DLMC winding can produce the highest average torque at high currents and achieve the highest peak efficiency as well.In order to compare with the conventional synchronous reluctance machines(SynRMs)having flux barriers inside the rotor,the appropriate rotor topologies to obtain the maximum average torque have been investigated for different winding configurations and slot/pole number combinations.Furthermore,some prototypes have been built with different winding configurations,stator structures,and slot/pole combinations to validate the predictions.
文摘The investigations on the dynamies of the PBL have been developed in recent years. Some authors emphasized macro-dynamics and others emphasized micro-structure of the PBL. In this paper, we study and review some main characteristics of the wind field in the PBL from the view point connecting the macro-dynamics and micro-stucture of the PBL, thus providing the physical basis for the further research of the dynamics and the parameterization of the PBL.
基金supported by National Key Basic Research Program of China (No: 2014CB239603)National Natural Science Foundation of China (Grants No 51506085)Natural Science Foundation of Jiangsu Province (Grants No BK20150742)
文摘This paper proposed an analytical model which can calculate the effective thermal conductivity (ETC) of a spiral-wound Lithium-ion battery (Li-ion battery). It bases on a two-dimensional energy balance with both radial and spiral heat transfer, as well as internal thermal contact resistance (TCR) considered simultaneously and studies the influence of winding layers and winding tension on the ETC. Results show that the analytical data are in good agreement with the numerical results. With the winding layers decreased and the winding tension enhanced, the ETC of Li-ion battery increases gradually. The radial temperature in Li-ion battery is also investigated which demonstrates a relatively higher temperature when considering the internal TCR.
基金Supported by the Strategic Priority Research Program of the Chinese Academy of Sciences(XDA17010105)Science and Technology Development Plan Project of Jilin Province(20180201035SF)+1 种基金Flexible Talents Introducing Project of Xinjiang(2019)National Key Scientific and Technological Infrastructure Project“Earth System Numerical Simulation Facility”(EarthLab).
文摘This study investigates the variation in the stratospheric quasi-zero wind layer(QZWL)over Dunhuang,Gansu Province,China,on 9 August 2020 using sounding observations from the Dunhuang national reference station and the fifth generation of ECMWF atmospheric reanalysis data(ERA5).The QZWL over Dunhuang was located between 18.6 and 20.4 km on 9 August 2020.The South Asian high(SAH)and subtropical westerly jet jointly affected the QZWL.As the SAH retreated westward,the upper-level westerly jet over Dunhuang strengthened,and the jet axis height increased.As a result,the zonal westerly wind was lifted to a higher altitude,and the wind speed of 100–70 hPa increased,raising the QZWL.In addition,the east–west oscillation of the SAH occurred earlier than the adjustment of the QZWL altitude,which can be used as a forecasting indicator for the QZWL.To further explore the mechanism responsible for the QZWL adjustment,the forcing terms in the equations for zonal wind,kinetic energy,and vertical wind shear were analyzed.The results showed that the upper-level geopotential gradient was the basic physical factor forcing the local change in zonal wind and kinetic energy.The change in zonal wind and kinetic energy led to the uplift of the QZWL.The results revealed that the vertical shear of horizontal wind could adequately indicate the stratospheric QZWL location.
文摘The vertical transport of mass at the top of the boundary layer is considered as a link between the boundary layer and free atmosphere.The adjustment of the wind and pressure fields in the boundary layer is studied under the consideration of the interaction between the boundary layer and free atmosphere.The vertical motion at the top of the boundary layer is evaluated.The results show that the distinguished differ- ences of the present results from classical Ekman layer do exist and they are discussed in the paper.
文摘In this paper,under the assumption of neutral and barotropic atmosphere,by means of the analytic solution of motion equation of PBL,the influences of nonstationary process on the internal parameters u_*/A(A is the wind speed at the top of PBL)and ■(the angle between winds near the surface and at the top of PBL)of PBL are investigated in which the wind direction at the top of PBL is a periodic function of time but the wind speed at the top of PBL does not change.The u_*/A increases and ■ decreases when the wind direction at the top of PBL rotates anticlockwise and vice versa.Hence the parameterization of PBL in the large-scale models derived under the stationary condition should be corrected by accounting for the nonstationary process.The similar results are obtained in the numerical solution of the motion equation of PBL.The influences of this nonstationary process on the profiles of the wind in PBL are also analyzed.
