Polarization feature is one of the important features of radar targets,which has been used in many fields.In this paper,the grid models of some typical foreign moving targets are constructed on the simulation platform...Polarization feature is one of the important features of radar targets,which has been used in many fields.In this paper,the grid models of some typical foreign moving targets are constructed on the simulation platform,such as glider,cruiser,fixed wing aircraft,and rotorcraft.The electromagnetic scattering characteristics of the moving platforms under the incidence of circular polarization waves are calculated.The typical polarization characteristics which the orthogonal and in-phase components have in the echoes are analyzed and proved.Based on the polarization scattering matrix(PSM)theory,from the point of view of the physical reproduction,the technical status quo that the existing technical approaches are difficult to realize the passive simulation of polarization characteristic of the target is summarized.To solve this problem,combined with the vector synthesis law,the realization mechanism of controllable polarization characteristic of target echoes is proposed,the analytical expressions of polarization control matrix and polarization ratio are deduced,and the controllability of polarization ratio feature in the case of circular polarization is verified by simulation calculation.展开更多
Load behavior is one of the most critical factors affecting mills＇ energy consumption and grinding efficiency, and is greatly affected by the liner profiles. Generally, as liner profiles vary, the ball mill performan...Load behavior is one of the most critical factors affecting mills＇ energy consumption and grinding efficiency, and is greatly affected by the liner profiles. Generally, as liner profiles vary, the ball mill performances are extremely different. In order to study the performance of the ball mill with regular polygon angle-spiral liners（RPASLs）, experimental and numerical studies on three types of RPASLs, including regular quadrilateral, pentagonal and hexagonal, are carried out. For the fine product of desired size, two critical parameters are analyzed： the energy input to the mill per unit mass of the fine product, E＊, and the rate of production of the fine product, F＊. Results show that the optimal structure of RPASLs is Quadrilateral ASL with an assembled angle of 50°. Under this condition, the specific energy consumption E＊ has the minimum value of 303 J per fine product and the production rate F＊ has the maximum value of 0.323. The production rate F＊ in the experimental result is consistent with the specific collision energy intensity to total collision energy intensity ratio Es/Et in the simulation. The relations between the production rate F＊ and the specific energy consumption E＊ with collision energy intensity Es and Et are obtained. The simulation result reveals the essential reason for the experimental phenomenon and correlates the mill performance parameter to the collision energy between balls, which could guide the practical application for Quadrilateral ASL.展开更多
The photonic crystal structure has attracted much attention due to its ability to confine light.In this paper,we present our study on an improved Smith-Purcell radiation from a simple metal photonic crystal excited by...The photonic crystal structure has attracted much attention due to its ability to confine light.In this paper,we present our study on an improved Smith-Purcell radiation from a simple metal photonic crystal excited by moving electrons.Different from the wide-band Smith-Purcell radiation from a single metal grating,the results show that the injected electrons could induce more dipole oscillations inside the multi-grating structure,and it leads to the enhancement of the radiation intensity.In addition,there are strong resonances in metal multi-grating structure,and the resonance characteristics may narrow the radiation band,which leads to a radiation with an obvious peak in the spectrum.Therefore,the multi-grating structure has the ability to enhance the radiation intensity and shape the radiation frequency band.By optimizing the structure parameters,coherent and tunable Smith-Purcell radiation can be realized,and it provides a potential way to develop band-controllable light or THz radiation source.展开更多
Methcathinone(MCAT)belongs to the designer drugs called synthetic cathinones,which are abused worldwide for recreational purposes.It has strong stimulant effects,including enhanced euphoria,sensation,alertness,and emp...Methcathinone(MCAT)belongs to the designer drugs called synthetic cathinones,which are abused worldwide for recreational purposes.It has strong stimulant effects,including enhanced euphoria,sensation,alertness,and empathy.However,little is known about how MCAT modulates neuronal activity in vivo.Here,we evaluated the effect of MCAT on neuronal activity with a series of functional approaches.C-Fos immunostaining showed that MCAT increased the number of activated neurons by 6-fold,especially in sensory and motor cortices,striatum,and midbrain motor nuclei.In vivo single-unit recording and two-photon Ca^(2+) imaging revealed that a large proportion of neurons increased spiking activity upon MCAT administration.Notably,MCAT induced a strong de-correlation of population activity and increased trial-to-trial reliability,specifically during a natural movie stimulus.It improved the information-processing efficiency by enhancing the single-neuron coding capacity,suggesting a cortical network mechanism of the enhanced perception produced by psychoactive stimulants.展开更多
基金supported by the National Natural Science Foundation of China(11927803A020414).
文摘Polarization feature is one of the important features of radar targets,which has been used in many fields.In this paper,the grid models of some typical foreign moving targets are constructed on the simulation platform,such as glider,cruiser,fixed wing aircraft,and rotorcraft.The electromagnetic scattering characteristics of the moving platforms under the incidence of circular polarization waves are calculated.The typical polarization characteristics which the orthogonal and in-phase components have in the echoes are analyzed and proved.Based on the polarization scattering matrix(PSM)theory,from the point of view of the physical reproduction,the technical status quo that the existing technical approaches are difficult to realize the passive simulation of polarization characteristic of the target is summarized.To solve this problem,combined with the vector synthesis law,the realization mechanism of controllable polarization characteristic of target echoes is proposed,the analytical expressions of polarization control matrix and polarization ratio are deduced,and the controllability of polarization ratio feature in the case of circular polarization is verified by simulation calculation.
基金Supported by National Natural Science Foundation of China(Grant Nos.51675484,51275474,51505424)Zhejiang Provincial Natural Science Foundation of China(Grant Nos.LZ12E05002,LY15E050019)
文摘Load behavior is one of the most critical factors affecting mills＇ energy consumption and grinding efficiency, and is greatly affected by the liner profiles. Generally, as liner profiles vary, the ball mill performances are extremely different. In order to study the performance of the ball mill with regular polygon angle-spiral liners（RPASLs）, experimental and numerical studies on three types of RPASLs, including regular quadrilateral, pentagonal and hexagonal, are carried out. For the fine product of desired size, two critical parameters are analyzed： the energy input to the mill per unit mass of the fine product, E＊, and the rate of production of the fine product, F＊. Results show that the optimal structure of RPASLs is Quadrilateral ASL with an assembled angle of 50°. Under this condition, the specific energy consumption E＊ has the minimum value of 303 J per fine product and the production rate F＊ has the maximum value of 0.323. The production rate F＊ in the experimental result is consistent with the specific collision energy intensity to total collision energy intensity ratio Es/Et in the simulation. The relations between the production rate F＊ and the specific energy consumption E＊ with collision energy intensity Es and Et are obtained. The simulation result reveals the essential reason for the experimental phenomenon and correlates the mill performance parameter to the collision energy between balls, which could guide the practical application for Quadrilateral ASL.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61921002,62171098,and 92163204)。
文摘The photonic crystal structure has attracted much attention due to its ability to confine light.In this paper,we present our study on an improved Smith-Purcell radiation from a simple metal photonic crystal excited by moving electrons.Different from the wide-band Smith-Purcell radiation from a single metal grating,the results show that the injected electrons could induce more dipole oscillations inside the multi-grating structure,and it leads to the enhancement of the radiation intensity.In addition,there are strong resonances in metal multi-grating structure,and the resonance characteristics may narrow the radiation band,which leads to a radiation with an obvious peak in the spectrum.Therefore,the multi-grating structure has the ability to enhance the radiation intensity and shape the radiation frequency band.By optimizing the structure parameters,coherent and tunable Smith-Purcell radiation can be realized,and it provides a potential way to develop band-controllable light or THz radiation source.
基金supported by the National Natural Science Foundation of China(31871089 and 31871028)Junior Thousand Talents Program of China,Fundamental Research Funds for the Central Universities(HUST:2172019kfyXKJC077 and HUST:2172019kfyRCPY064)Key Laboratory of Forensic Toxicology,Ministry of Public Security of China(Beijing Municipal Public Security Bureau:2020FTDWFX02 and 2019FTDWFX06).
文摘Methcathinone(MCAT)belongs to the designer drugs called synthetic cathinones,which are abused worldwide for recreational purposes.It has strong stimulant effects,including enhanced euphoria,sensation,alertness,and empathy.However,little is known about how MCAT modulates neuronal activity in vivo.Here,we evaluated the effect of MCAT on neuronal activity with a series of functional approaches.C-Fos immunostaining showed that MCAT increased the number of activated neurons by 6-fold,especially in sensory and motor cortices,striatum,and midbrain motor nuclei.In vivo single-unit recording and two-photon Ca^(2+) imaging revealed that a large proportion of neurons increased spiking activity upon MCAT administration.Notably,MCAT induced a strong de-correlation of population activity and increased trial-to-trial reliability,specifically during a natural movie stimulus.It improved the information-processing efficiency by enhancing the single-neuron coding capacity,suggesting a cortical network mechanism of the enhanced perception produced by psychoactive stimulants.
