We propose a simple scheme for trapping cold polar molecules in low-field seeking states on the surface of a chip by using a grounded metal plate and two finite-length charged wires that half embanked in an insulating...We propose a simple scheme for trapping cold polar molecules in low-field seeking states on the surface of a chip by using a grounded metal plate and two finite-length charged wires that half embanked in an insulating suhstrate, calculate the electric field distributions generated by our charged-wire layout in free space and the corresponding Stark potentials for ND3 molecules, and analyze the dependence of the trapping center position on the geometric parameters. Moreover, the loading and trapping processes of cold ND3 molecules are studied by using the Monte Carlo method. Our study shows that the loading efficiency of the trap scheme can reach 11.5%, and the corresponding temperature of the trapped cold molecules is about 26.4 inK.展开更多
We propose a versatile electrostatic trap scheme using several charged spherical electrodes and a bias electric held.We hrst give the two-ball scheme and derive the analytical solution of the electric held.In order to...We propose a versatile electrostatic trap scheme using several charged spherical electrodes and a bias electric held.We hrst give the two-ball scheme and derive the analytical solution of the electric held.In order to make a comparison,we also give the numerical solution calculated by the hnite element software(Ansoft Maxwell).Considering the loading of cold polar molecules into the trap,we give the three-ball scheme.We hrst give the analytical and numerical solutions of the distribution of the electric held.Then we simulate the dynamic process of the loading and trapping cold molecules using the classical Monte Carlo method.We analyze the influence of the velocity of the incident molecular beam and the loading time on the loading efficiency.After that,we give the temperature of the trapped cold molecules.Our study shows that the loading efficiency can reach 82%,and the corresponding temperature of the trapped molecules is about 24.6 mK.At last,we show that the single well divides into two ones by increasing the bias electric held or decreasing the voltages applied to the spherical electrodes.展开更多
Metasurfaces that can realize the polarization manipulation of electromagnetic waves on the sub-wavelength scale have become an emerging research field.Here,a novel strategy of combining the metasurface and Fresnel zo...Metasurfaces that can realize the polarization manipulation of electromagnetic waves on the sub-wavelength scale have become an emerging research field.Here,a novel strategy of combining the metasurface and Fresnel zone plate to form a metasurface zone plate is proposed to realize the conversion from nearly arbitrary polarizations to a fixed polarization.Specifically,when one polarized wave is incident on adjacent ring zones constructed by different types of meta-atoms,the transmitted waves generated by odd-numbered and even-numbered ring zones converge at the same focus and superimpose to generate a fixed polarized wave.As function demonstrations,we have designed two types of metasurface zone plates:one is a focused linear polarizer,and the other can convert nearly arbitrary polarized waves into focused circularly polarized waves.The simulated and measured results are consistent with theoretical expectations,suggesting that the proposed concept is flexible and feasible.Our work provides an alternative platform for polarization manipulation and may vigorously promote the development of polarization photonic devices.展开更多
The title problem is systematically analyzed by the differential quadrature (DQ) method. Estimates of the critical buckling loads are obtained for combinations of various boundary conditions, internal and/or external ...The title problem is systematically analyzed by the differential quadrature (DQ) method. Estimates of the critical buckling loads are obtained for combinations of various boundary conditions, internal and/or external Pressures, hole sizes,and rigidity ratios. A comparison is made with existing results for certain cases. Numerical investigation has been carried out with regard to the convergence of the solutions. It is found that accurate results are obtained with only nine or eleven grid points.展开更多
The effect of Pasternak foundation and non-homogenity on the axisymmetric vibrations of polar orthotropic parabolically varying tapered circular plates has been analyzed on the basis of classical plate theory. Ritz me...The effect of Pasternak foundation and non-homogenity on the axisymmetric vibrations of polar orthotropic parabolically varying tapered circular plates has been analyzed on the basis of classical plate theory. Ritz method has been used to find the numerical solution of the specified problem. The efficiency of the Ritz method depends on the choice of basis function based upon deflection of polar orthotropic plates. The effects of different plate parameters viz. elastic foundation, non-homogeneity, taper parameter and that of orthotropy on fundamental, second and third mode of vibration have been studied for clamped and simply-supported boundary conditions. Mode shapes for specified plates have been drawn for both the boundary conditions. Convergence and comparison studies have been carried out for specified plates.展开更多
Ships and other mobile pollution sources emitted massive ultrafine and low-resistivity particles containing black carbon(BC),which were harmful to human health and were difficult to capture by conventional electrostat...Ships and other mobile pollution sources emitted massive ultrafine and low-resistivity particles containing black carbon(BC),which were harmful to human health and were difficult to capture by conventional electrostatic precipitators(ESPs).In this study,nanoscale carbon black was adopted as simulated particles(SP)with similar physicochemical properties for black carbon emitted from ships(SP-BC)to investigate the feasibility of using an ESP with square-grooved collecting plates for the removal of SP-BC at low backpressures.The increased applied voltage significantly improved the total collection of SP-BC whereas may also promote the conversion of relatively larger particle size SP-BC into nano-size below 20nm.The outlet number concentration of SP-BC under 27 kV at 130℃was three times that of the inlet.While the reduction of the flow rate could strengthen the capture of SP-BC below20 nm,and under the combined action of low flow rate and maximum applied voltage,the collection efficiency of 20-100 nm SP-BC could exceed 90%.In addition,the escape and capture characteristics of SP-BC under long-term rapping were revealed.The square-grooved collecting plate could effectively restrain the re-entrainment of collected SP-BC generated by rapping,and the nanoscale SP-BC was trapped in the grooves after rapping.The results could provide insights into the profound removal of massive nanoscale black carbon emissions from mobile sources.展开更多
A foil–microchannel plate(MCP)detector,which uses electrostatic lenses and possesses both good position and timing resolutions,has been designed and simulated for beam diagnostics and mass measurements at the next-ge...A foil–microchannel plate(MCP)detector,which uses electrostatic lenses and possesses both good position and timing resolutions,has been designed and simulated for beam diagnostics and mass measurements at the next-generation heavy-ion-beam facility HIAF in China.Characterized by low energy loss and good performances of timing and position measurements,it would be located at focal planes in fragment separator HFRS for position monitoring,beam turning,Bq measurement,and trajectory reconstruction.Moreover,it will benefit the building-up of a magnetic-rigidity–energy-loss–time-offlight(BqDETOF)method at HFRS for high-precision in-flight particle identification of radioactive isotope beams on an event-by-event basis.Most importantly,the detector can be utilized for in-ring TOF and position measurements,beam-line TOF measurements at two achromatic foci,and position measurements at a dispersive focus of HFRS,thus making it possible to use two complementary mass measurement methods[isochronous mass spectrometry at the storage ring SRing and magnetic-rigidity–time-of-flight(BqTOF)at the beam-line HFRS]in one single experimental run.展开更多
The lithium(Li) metal anode is an integral component in an emerging high-energy-density rechargeable battery.A composite Li anode with a three-dimensional(3 D) host exhibits unique advantages in suppressing Li dendrit...The lithium(Li) metal anode is an integral component in an emerging high-energy-density rechargeable battery.A composite Li anode with a three-dimensional(3 D) host exhibits unique advantages in suppressing Li dendrites and maintaining dimensional stability.However,the fundamental understanding and regulation of solid electrolyte interphase(SEI),which directly dictates the behavior of Li plating/stripping,are rarely researched in composite Li metal anodes.Herein,the interaction between a polar polymer host and solvent molecules was proposed as an emerging but effective strategy to enable a stable SEI and a uniform Li deposition in a working battery.Fluoroethylene carbonate molecules in electrolytes are enriched in the vicinity of a polar polyacrylonitrile(PAN) host due to a strong dipole-dipole interaction,resulting in a LiF-rich SEI on Li metal to improve the uniformity of Li deposition.A composite Li anode with a PAN host delivers 145 cycles compared with 90 cycles when a non-polar host is employed.Moreover,60 cycles are demonstrated in a 1:0 Ah pouch cell without external pressure.This work provides a fresh guidance for designing practical composite Li anodes by unraveling the vital role of the synergy between a 3 D host and solvent molecules for regulating a robust SEI.展开更多
A novel tunable comb filter composed of a single-mode/multimode/polarization-maintaining-fiber-based Sagnac fiber loop is proposed and experimentally demonstrated.The filter tunability is achieved by rotating the pola...A novel tunable comb filter composed of a single-mode/multimode/polarization-maintaining-fiber-based Sagnac fiber loop is proposed and experimentally demonstrated.The filter tunability is achieved by rotating the polarization controller.The spectral shift is dependent on rotation direction and the position of the polarization controller.In addition,the adjustable range achieved by rotating the half-wave-plate polarization controller is twice higher than that of the quarter-wave-plate one.展开更多
In this paper, we present a two-dimensional(2D) fully analytical model with consideration of polarization effect for the channel potential and electric field distributions of the gate field-plated high electron mobili...In this paper, we present a two-dimensional(2D) fully analytical model with consideration of polarization effect for the channel potential and electric field distributions of the gate field-plated high electron mobility transistor(FP-HEMT)on the basis of 2D Poisson's solution. The dependences of the channel potential and electric field distributions on drain bias, polarization charge density, FP structure parameters, AlGaN/GaN material parameters, etc. are investigated. A simple and convenient approach to designing high breakdown voltage FP-HEMTs is also proposed. The validity of this model is demonstrated by comparison with the numerical simulations with Silvaco–Atlas. The method in this paper can be extended to the development of other analytical models for different device structures, such as MIS-HEMTs, multiple-FP HETMs,slant-FP HEMTs, etc.展开更多
基金Project supported by the National Natural Science Foundation of China （Grant Nos. 10674047, 10804031, 10904037, 10974055, 11034002, and 11274114）, the National Basic Research Program of China （Grant Nos. 2006CB921604 and 2011 CB921602）, the Basic Key Program of Shanghai Municipality of China （Grant No. 07JCI4017）, and the Leading Academic Discipline Project of Shanghai Municipality of China （Grant No. 8408）.
文摘We propose a simple scheme for trapping cold polar molecules in low-field seeking states on the surface of a chip by using a grounded metal plate and two finite-length charged wires that half embanked in an insulating suhstrate, calculate the electric field distributions generated by our charged-wire layout in free space and the corresponding Stark potentials for ND3 molecules, and analyze the dependence of the trapping center position on the geometric parameters. Moreover, the loading and trapping processes of cold ND3 molecules are studied by using the Monte Carlo method. Our study shows that the loading efficiency of the trap scheme can reach 11.5%, and the corresponding temperature of the trapped cold molecules is about 26.4 inK.
基金Project supported by the National Nature Science Foundation of China(Grant No.11504318)
文摘We propose a versatile electrostatic trap scheme using several charged spherical electrodes and a bias electric held.We hrst give the two-ball scheme and derive the analytical solution of the electric held.In order to make a comparison,we also give the numerical solution calculated by the hnite element software(Ansoft Maxwell).Considering the loading of cold polar molecules into the trap,we give the three-ball scheme.We hrst give the analytical and numerical solutions of the distribution of the electric held.Then we simulate the dynamic process of the loading and trapping cold molecules using the classical Monte Carlo method.We analyze the influence of the velocity of the incident molecular beam and the loading time on the loading efficiency.After that,we give the temperature of the trapped cold molecules.Our study shows that the loading efficiency can reach 82%,and the corresponding temperature of the trapped molecules is about 24.6 mK.At last,we show that the single well divides into two ones by increasing the bias electric held or decreasing the voltages applied to the spherical electrodes.
文摘Metasurfaces that can realize the polarization manipulation of electromagnetic waves on the sub-wavelength scale have become an emerging research field.Here,a novel strategy of combining the metasurface and Fresnel zone plate to form a metasurface zone plate is proposed to realize the conversion from nearly arbitrary polarizations to a fixed polarization.Specifically,when one polarized wave is incident on adjacent ring zones constructed by different types of meta-atoms,the transmitted waves generated by odd-numbered and even-numbered ring zones converge at the same focus and superimpose to generate a fixed polarized wave.As function demonstrations,we have designed two types of metasurface zone plates:one is a focused linear polarizer,and the other can convert nearly arbitrary polarized waves into focused circularly polarized waves.The simulated and measured results are consistent with theoretical expectations,suggesting that the proposed concept is flexible and feasible.Our work provides an alternative platform for polarization manipulation and may vigorously promote the development of polarization photonic devices.
文摘The title problem is systematically analyzed by the differential quadrature (DQ) method. Estimates of the critical buckling loads are obtained for combinations of various boundary conditions, internal and/or external Pressures, hole sizes,and rigidity ratios. A comparison is made with existing results for certain cases. Numerical investigation has been carried out with regard to the convergence of the solutions. It is found that accurate results are obtained with only nine or eleven grid points.
文摘The effect of Pasternak foundation and non-homogenity on the axisymmetric vibrations of polar orthotropic parabolically varying tapered circular plates has been analyzed on the basis of classical plate theory. Ritz method has been used to find the numerical solution of the specified problem. The efficiency of the Ritz method depends on the choice of basis function based upon deflection of polar orthotropic plates. The effects of different plate parameters viz. elastic foundation, non-homogeneity, taper parameter and that of orthotropy on fundamental, second and third mode of vibration have been studied for clamped and simply-supported boundary conditions. Mode shapes for specified plates have been drawn for both the boundary conditions. Convergence and comparison studies have been carried out for specified plates.
基金Project supported by the National Natural Science Foundation of China （Grant Nos 10174050, 10374029, 10434060 and 10674047）, the National Basic Research Program of China （Grant No 2006CB921604）, the Science and Technology Commission of Shanghai Municipality （Grant No 04DZ14009）, Shanghai Priority Academic Discipline, the 211 Foundation of the Ministry of Education, China.
基金Project supported by the National Natural Science Foundation of China （Grant Nos 10174050, 10374029, 10434046 and 10674047） and the Science and Technology Commission of Shanghai Municipality, China （Grant No 04DZ14009）, Shanghai Priority Academic Discipline and the 211 Foundation of the Educational Ministry of China.
基金supported by the National Natural Science Foundation (No.52076191)Key Research&Development Plan of Shandong Province (No.2020CXGC011401)。
文摘Ships and other mobile pollution sources emitted massive ultrafine and low-resistivity particles containing black carbon(BC),which were harmful to human health and were difficult to capture by conventional electrostatic precipitators(ESPs).In this study,nanoscale carbon black was adopted as simulated particles(SP)with similar physicochemical properties for black carbon emitted from ships(SP-BC)to investigate the feasibility of using an ESP with square-grooved collecting plates for the removal of SP-BC at low backpressures.The increased applied voltage significantly improved the total collection of SP-BC whereas may also promote the conversion of relatively larger particle size SP-BC into nano-size below 20nm.The outlet number concentration of SP-BC under 27 kV at 130℃was three times that of the inlet.While the reduction of the flow rate could strengthen the capture of SP-BC below20 nm,and under the combined action of low flow rate and maximum applied voltage,the collection efficiency of 20-100 nm SP-BC could exceed 90%.In addition,the escape and capture characteristics of SP-BC under long-term rapping were revealed.The square-grooved collecting plate could effectively restrain the re-entrainment of collected SP-BC generated by rapping,and the nanoscale SP-BC was trapped in the grooves after rapping.The results could provide insights into the profound removal of massive nanoscale black carbon emissions from mobile sources.
基金supported by the National Natural Science Foundation of China(Nos.11605248,11605249,11605267,and 11805032.)
文摘A foil–microchannel plate(MCP)detector,which uses electrostatic lenses and possesses both good position and timing resolutions,has been designed and simulated for beam diagnostics and mass measurements at the next-generation heavy-ion-beam facility HIAF in China.Characterized by low energy loss and good performances of timing and position measurements,it would be located at focal planes in fragment separator HFRS for position monitoring,beam turning,Bq measurement,and trajectory reconstruction.Moreover,it will benefit the building-up of a magnetic-rigidity–energy-loss–time-offlight(BqDETOF)method at HFRS for high-precision in-flight particle identification of radioactive isotope beams on an event-by-event basis.Most importantly,the detector can be utilized for in-ring TOF and position measurements,beam-line TOF measurements at two achromatic foci,and position measurements at a dispersive focus of HFRS,thus making it possible to use two complementary mass measurement methods[isochronous mass spectrometry at the storage ring SRing and magnetic-rigidity–time-of-flight(BqTOF)at the beam-line HFRS]in one single experimental run.
基金supported by the National Natural Science Foundation of China (21825501 and U1932220)the National Key Research and Development Program (2016YFA0202500)+2 种基金the Seed Fund of Shanxi Research Institute for Clean Energy (SXKYJF015)the Scientific and technological Key Project of Shanxi Province (20191102003)the Tsinghua University Initiative Scientific Research Program.
文摘The lithium(Li) metal anode is an integral component in an emerging high-energy-density rechargeable battery.A composite Li anode with a three-dimensional(3 D) host exhibits unique advantages in suppressing Li dendrites and maintaining dimensional stability.However,the fundamental understanding and regulation of solid electrolyte interphase(SEI),which directly dictates the behavior of Li plating/stripping,are rarely researched in composite Li metal anodes.Herein,the interaction between a polar polymer host and solvent molecules was proposed as an emerging but effective strategy to enable a stable SEI and a uniform Li deposition in a working battery.Fluoroethylene carbonate molecules in electrolytes are enriched in the vicinity of a polar polyacrylonitrile(PAN) host due to a strong dipole-dipole interaction,resulting in a LiF-rich SEI on Li metal to improve the uniformity of Li deposition.A composite Li anode with a PAN host delivers 145 cycles compared with 90 cycles when a non-polar host is employed.Moreover,60 cycles are demonstrated in a 1:0 Ah pouch cell without external pressure.This work provides a fresh guidance for designing practical composite Li anodes by unraveling the vital role of the synergy between a 3 D host and solvent molecules for regulating a robust SEI.
基金supported by the National Natural Science Foundation of China (Grant Nos. 11274181,10974100,and 10674075)the Tianjin Key Program of Application Foundations and Future Technology Research Project,China (Grant No. 10JCZDJC24300)the Specialized Research Fund for the Doctoral Program of Higher Education of China (Grant No. 20120031110033)
文摘A novel tunable comb filter composed of a single-mode/multimode/polarization-maintaining-fiber-based Sagnac fiber loop is proposed and experimentally demonstrated.The filter tunability is achieved by rotating the polarization controller.The spectral shift is dependent on rotation direction and the position of the polarization controller.In addition,the adjustable range achieved by rotating the half-wave-plate polarization controller is twice higher than that of the quarter-wave-plate one.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61204085 and 61334002)the Fundamental Research Funds for the Central Universities,China(Grant No.K5051225013)
文摘In this paper, we present a two-dimensional(2D) fully analytical model with consideration of polarization effect for the channel potential and electric field distributions of the gate field-plated high electron mobility transistor(FP-HEMT)on the basis of 2D Poisson's solution. The dependences of the channel potential and electric field distributions on drain bias, polarization charge density, FP structure parameters, AlGaN/GaN material parameters, etc. are investigated. A simple and convenient approach to designing high breakdown voltage FP-HEMTs is also proposed. The validity of this model is demonstrated by comparison with the numerical simulations with Silvaco–Atlas. The method in this paper can be extended to the development of other analytical models for different device structures, such as MIS-HEMTs, multiple-FP HETMs,slant-FP HEMTs, etc.
