Given that the strength of statistics lies in modelling,we are motivated to do a comparative statistical study between two types of ragas,one being aesthetically known to be restful and the other restless in nature.We...Given that the strength of statistics lies in modelling,we are motivated to do a comparative statistical study between two types of ragas,one being aesthetically known to be restful and the other restless in nature.We first try to distinguish these two types through statistical modeling.To substantiate our findings,two more sta-tistical features are considered in the paper to separate the two categories of ragas,namely the rate of change of pitch and inter-onset interval.The experimental results are encouraging.展开更多
Switched reluctance motor(SRM)usually adopts Direct Instantaneous Torque Control(DITC)to suppress torque ripple.However,due to the fixed turn-on angle and the control mode of the two-phase exchange region,the conventi...Switched reluctance motor(SRM)usually adopts Direct Instantaneous Torque Control(DITC)to suppress torque ripple.However,due to the fixed turn-on angle and the control mode of the two-phase exchange region,the conventional DITC control method has low adaptability in different working conditions,which will lead to large torque ripple.For this problem,an improved DITC control method based on turn-on angle optimization is proposed in this paper.Firstly,the improved BP neural network is used to construct a nonlinear torque model,so that the torque can be accurately fed back in real time.Secondly,the turn-on angle optimization algorithm based on improved GRNN neural network is established,so that the turn-on angle can be adjusted adaptively online.Then,according to the magnitude of inductance change rate,the two-phase exchange region is divided into two regions,and the phase with larger inductance change rate and current is selected to provide torque in the sub-regions.Finally,taking a 3-phase 6/20 SRM as example,simulation and experimental verification are carried out to verify the effectiveness of this method.展开更多
The heat transfer efficiency of a thermal energy storage unit(TESU)can be improved by the addition of novel longitudinal fins.A series of TESUs are analyzed using the finite volume method(FVM)to determine the effect o...The heat transfer efficiency of a thermal energy storage unit(TESU)can be improved by the addition of novel longitudinal fins.A series of TESUs are analyzed using the finite volume method(FVM)to determine the effect of fin angle on the heat transfer performance.As the fin angle increases,the TES rate first increases,then decreases,reaching a maximum rate at 60°,where the melting time is less by 30.9%,28.58%,21.99%,9.02%,and 18.1%than at 0°,15°,30°,45°,and 80°,respectively.In addition,it is found that the melting time of the phase change material is significantly greater at the bottom of the TESU.The time percentage of this stage decreases as the fin angle increases through these percentages by 7%,14%,23%,33%,and 20%,respectively.Further,the response surface methodology(RSM)is applied to optimize the longitudinal fin by minimizing the total melting time.The analysis concludes that a fin angle of 58.68°reduces the complete melting time of the stearic acid by 44%below the time at 0°.These findings fill a gap in knowledge of the effect on melting performance of the design angle of longitudinal fins and provide a reference for the design of horizontally placed longitudinal finned thermal energy storage units.展开更多
文摘Given that the strength of statistics lies in modelling,we are motivated to do a comparative statistical study between two types of ragas,one being aesthetically known to be restful and the other restless in nature.We first try to distinguish these two types through statistical modeling.To substantiate our findings,two more sta-tistical features are considered in the paper to separate the two categories of ragas,namely the rate of change of pitch and inter-onset interval.The experimental results are encouraging.
基金supported by National Natural Science Foundation of China under Grant 52167005Science and Technology Research Project of Jiangxi Provincial Department of Education under Grant GJJ200826。
文摘Switched reluctance motor(SRM)usually adopts Direct Instantaneous Torque Control(DITC)to suppress torque ripple.However,due to the fixed turn-on angle and the control mode of the two-phase exchange region,the conventional DITC control method has low adaptability in different working conditions,which will lead to large torque ripple.For this problem,an improved DITC control method based on turn-on angle optimization is proposed in this paper.Firstly,the improved BP neural network is used to construct a nonlinear torque model,so that the torque can be accurately fed back in real time.Secondly,the turn-on angle optimization algorithm based on improved GRNN neural network is established,so that the turn-on angle can be adjusted adaptively online.Then,according to the magnitude of inductance change rate,the two-phase exchange region is divided into two regions,and the phase with larger inductance change rate and current is selected to provide torque in the sub-regions.Finally,taking a 3-phase 6/20 SRM as example,simulation and experimental verification are carried out to verify the effectiveness of this method.
基金supported by the National Natural Science Foundation of China(No.51766012)the Inner Mongolia Science and Technology Major Project(No.2020ZD0017)+1 种基金the Science and Technology Research Project of Inner Mongolia Autonomous Region(No.2021GG0252)the Basic research business fund projects for Universities directly under the Inner Mongolia Autonomous Region(No.JY20220107)。
文摘The heat transfer efficiency of a thermal energy storage unit(TESU)can be improved by the addition of novel longitudinal fins.A series of TESUs are analyzed using the finite volume method(FVM)to determine the effect of fin angle on the heat transfer performance.As the fin angle increases,the TES rate first increases,then decreases,reaching a maximum rate at 60°,where the melting time is less by 30.9%,28.58%,21.99%,9.02%,and 18.1%than at 0°,15°,30°,45°,and 80°,respectively.In addition,it is found that the melting time of the phase change material is significantly greater at the bottom of the TESU.The time percentage of this stage decreases as the fin angle increases through these percentages by 7%,14%,23%,33%,and 20%,respectively.Further,the response surface methodology(RSM)is applied to optimize the longitudinal fin by minimizing the total melting time.The analysis concludes that a fin angle of 58.68°reduces the complete melting time of the stearic acid by 44%below the time at 0°.These findings fill a gap in knowledge of the effect on melting performance of the design angle of longitudinal fins and provide a reference for the design of horizontally placed longitudinal finned thermal energy storage units.
