We fabricate three surface patterning zinc oxide（ZnO） ordered arrays on glass substrates by using nanosphere lithography technique and dc magnetron sputtering technique. The crescent, tube and honeycomb surface morp...We fabricate three surface patterning zinc oxide（ZnO） ordered arrays on glass substrates by using nanosphere lithography technique and dc magnetron sputtering technique. The crescent, tube and honeycomb surface morphologies of the samples are observed by scanning electron microscopy. The transmittance, fluorescence and confocal Raman spectra of the sample are measured. Obviously, when the angle between the plume and the substrate is 90°, the honeycomb arrays have a better transmission. Additionally, the PL intensity of honeycomb arrays is superior. With the increasing of the angle between the substrate and the sputtering plume, the fluorescence peak shows blue shift. The Raman peak located at438 cm^-1belongs to ZnO E2（high） mode, which corresponds to the characteristic band of the hexagonal wurtzite phase.The tube arrays have the best Raman spectrum intensity.展开更多
New methods of synthetizing nonequidistant sparse antenna arrays based on the properties of magic squares are studied.The methods of construction and algorithms of synthesis of two-dimensional antennas based on them p...New methods of synthetizing nonequidistant sparse antenna arrays based on the properties of magic squares are studied.The methods of construction and algorithms of synthesis of two-dimensional antennas based on them providing a high degreeof dilution and sufficiently small side radiation are proposed.The methods for construction of such antennas and their maincharacteristics are considered.展开更多
On the basis of the second order solution of two-dimensional random gravity waves in finite uniform depth,which is rederived by a perturbation expansion method,the analytical expression of the second order spectrum is...On the basis of the second order solution of two-dimensional random gravity waves in finite uniform depth,which is rederived by a perturbation expansion method,the analytical expression of the second order spectrum is strictly deduced, and for infinite depth, the correct form of the kernel function is given for each octant do main.In fact,the present study improves and corrects the generally accepted results obtained by Tick展开更多
A two-dimensional nonlinear sloshing problem is analyzed by means of the fully nonlinear theory and time domain second order theory of water waves. Liquid sloshing in a rectangular container Subjected to a horizontal ...A two-dimensional nonlinear sloshing problem is analyzed by means of the fully nonlinear theory and time domain second order theory of water waves. Liquid sloshing in a rectangular container Subjected to a horizontal excitation is simulated by the finite element method. Comparisons between the two theories are made based on their numerical results. It is found that good agreement is obtained for the case of small amplitude oscillation and obvious differences occur for large amplitude excitation. Even though, the second order solution can still exhibit typical nonlinear features of nonlinear wave and can be used instead of the fully nonlinear theory.展开更多
The highly ordered silver-coated colloidal crystals arrays and macroporous silver films were derived through an electrostatics-induced adsorption effect using polystyrene(PS) as templates. Carboxyl-modified PS microsp...The highly ordered silver-coated colloidal crystals arrays and macroporous silver films were derived through an electrostatics-induced adsorption effect using polystyrene(PS) as templates. Carboxyl-modified PS microspheres were prepared by emulsifier-free emulsion polymerization using methacrylic acid(MAA) as the functional monomer. PS microspheres were self-assembled into close packing colloidal crystals of facecentered cubic arrays to the substrate with vertical deposition method. These colloidal crystals were modified using dopamine(DA) to form poly-dopamine(PDA) during its oxidative polymerization. Through electrostatic interaction, the silver nanoparticles were deposited and adsorbed onto the surfaces of colloidal crystals templates by exposing [Ag(NH_3)_2]^+solution to infrared irradiation. Removal of the polymeric template by etching with methylbenzene solvent resulted in 3D ordered macroporous silver films. The structural and properties of the ordered silver-coated arrays and macroporous silver films were characterized by field emission scanning electron microscopy(FE-SEM), X-ray diffraction(XRD), UV-vis spectroscopy and surface-enhanced Raman spectroscopy(SERS). The results indicate that the prepared silver-coated arrays and macroporous silver films possess the features of ordered multilayer arrangement, uniformity and repeatability as well as an ideal SERS effect.展开更多
Fabricating interfacial layers with high lithiophilicity and rapid Li+transfer functionality is critical for dendrite-free lithium deposition in lithium-metal batteries(LMBs).Herein,a two-dimensional coordination netw...Fabricating interfacial layers with high lithiophilicity and rapid Li+transfer functionality is critical for dendrite-free lithium deposition in lithium-metal batteries(LMBs).Herein,a two-dimensional coordination network,NKU-2000,with ordered lithiophilic crown ether sites is applied as an interfacial layer to protect lithium metal anode.The Li||Li symmetrical cells with NKU-2000-based interfacial layer exhibit an ultralong cycle of 8500 h at 1 mA cm^(-2),and can stably cycle for 1700 h under a severe state of 10 mA cm^(-2)and 10 mAh cm^(-2).The corresponding LiFePO_(4)full cell achieves a long lifespan of 2000 cycles at 1 C with a capacity retention rate of 81.8%.A molecular-level mechanism study reveals that the lithiophilic crown ether sites reduce the Li+desolvation energy barrier,and the crown ether-based channels promote Li^(+)transfer kinetics.This work provides a facile coordination assembly approach of arranging uniformly distributed lithiophilic sites in efficient Li^(+)transfer channels of an interfacial layer for achieving dendrite-free lithium deposition in high-performance LMBs.展开更多
Lithium-oxygen batteries have attracted considerable interest in the past a few years, because they have higher theoretical specific energy than Li-ion batteries. However, the available en ergy den sities of the Li-O2...Lithium-oxygen batteries have attracted considerable interest in the past a few years, because they have higher theoretical specific energy than Li-ion batteries. However, the available en ergy den sities of the Li-O2 batteries are much less than expected. It is particularly urgent to find catalyst with high activity. Herein, a series of Co3O4 with differe nt morphologies (ordered two-dimensio nal porous nano sheets, flowerlike and cuboidlike) were successfully prepared through facile hydrothermal and calcinatio n methods. Ordered two-dime nsional Co3O4 nano sheets show the best cycling stability. Detailed experimental results reveal that the superiority of the unique two-dimensional uniform porous structures is vital for Li-O2 batteries cathode catalysts. Due to the ordered structures with high surface areas and active sites, the catalysts indicate a high specific discharge capacity of about 10,417 mAh/g at a current density of 200 mA/g, and steadily cycle for more than 50 times with a limited capacity of 1,000 mAh/g.展开更多
Surface plasmon resonance of noble metal nanoparticles leads to the optical absorption enhancement effects,which have great potential applications in solar cell.By using the general numerical method of discrete dipole...Surface plasmon resonance of noble metal nanoparticles leads to the optical absorption enhancement effects,which have great potential applications in solar cell.By using the general numerical method of discrete dipole approximation （DDA）,we study the absorption and scattering properties of two-dimensional square silver nanodisks （2D SSN） arrays on the single crystal silicon solar cell.Based on the effective reflective index model of the single crystal silicon solar cell,we investigate the optical enhancement absorption of light energy by varying the light incident direction,particle size,aspect ratio,and interparticle spacing of the silver nanodisks.The peak values and position of the optical extinction spectra of the 2D square arrays of noble metal nanodisks are obtained with the different array structures.展开更多
Adaptive broadband beamforraing is a key issue in array applications. The adaptive broadband beamformer with tapped delay line （TDL） structure for nonuniform linear array （NLA） is designed according to the rule of...Adaptive broadband beamforraing is a key issue in array applications. The adaptive broadband beamformer with tapped delay line （TDL） structure for nonuniform linear array （NLA） is designed according to the rule of minimizing the beamformer＇s output power while keeping the distortionless response （DR） in the direction of desired signal and keeping the constant beamwidth （CB） with the prescribed sidelobe level over the whole operating band. This kind of beamforming problem can be solved with the interior-point method after being converted to the form of standard second order cone programming （SOCP）. The computer simulations are presented which illustrate the effectiveness of our beamformer.展开更多
This paper gives a MUSIC signal DOA estimation algorithm based on the modified high-order cumulant matrix which is constructed by the recieved data and their conjugate rearrangements. When the snapshot number is limit...This paper gives a MUSIC signal DOA estimation algorithm based on the modified high-order cumulant matrix which is constructed by the recieved data and their conjugate rearrangements. When the snapshot number is limited, this algorithm can improve the signal DOA estimation performances obviously, and its computational complexity scarcely increases. Finally, some simulation results to verify the theoretical analyses are presented.展开更多
随着电影对极致沉浸式视听体验的发展需求,沉浸式声场记录和重放技术日显重要。本文围绕电影音频制作技术中的声场记录和重放问题,介绍了基于球麦克风阵列的高阶高保真立体声(Higher Order Ambisonics,HOA)分析技术,并针对球麦克风阵列...随着电影对极致沉浸式视听体验的发展需求,沉浸式声场记录和重放技术日显重要。本文围绕电影音频制作技术中的声场记录和重放问题,介绍了基于球麦克风阵列的高阶高保真立体声(Higher Order Ambisonics,HOA)分析技术,并针对球麦克风阵列球谐分解中的低频噪声与高频混叠问题,以及双耳重放技术中的阶数受限问题,给出了相应解决方案,研究表明所提方案可为观众提供更真实、更具沉浸感的声场重放效果,提升了观影体验,在电影音频制作中具有广阔的应用前景。展开更多
A polarization-independent nonmechanical laser beam steering scheme is proposed to realize continuous two-dimensional（2 D） scanning with high efficiency, where the core components are two polarization-dependent devi...A polarization-independent nonmechanical laser beam steering scheme is proposed to realize continuous two-dimensional（2 D） scanning with high efficiency, where the core components are two polarization-dependent devices, which are called liquid crystal optical phased arrays（LC-OPAs）. These two one-dimensional（1D） devices are orthogonally cascaded to work on the state of azimuthal and elevation steering, respectively. Properties of polarization independence as well as 2D beam steering are mathematically and experimentally verified with a good agreement. Based on the experimental setup, linearly polarized beams with different polarization angles are steered with high accuracy. The measured angular deviations are less than 5 μrad, which is on the same order of the accuracy of the measurement system. This polarization-independent 2 D laser beam steering scheme has potential application for nonmechanical laser communication, lidar, and other LC-based systems.展开更多
In this paper, we report the growth and characteristics of titania nanotube arrays prepared by anodic oxidation and then annealed in an oxygen atmosphere at 500℃. The titania nanotube arrays presented high sensitivit...In this paper, we report the growth and characteristics of titania nanotube arrays prepared by anodic oxidation and then annealed in an oxygen atmosphere at 500℃. The titania nanotube arrays presented high sensitivity to hydrogen gas. The crystalline phase of the samples was checked by X-ray diffraction (XRD). The differences in the nanotubes morphology attributed to the etched samples due to anodiza- tion potential, reaction time and the electrolyte concentration were analyzed by scanning electron mi- croscopy (SEM). The gas sensitive parameters of the samples were obtained from resistance, the re- sponse time and the recovery time at different temperatures.展开更多
文摘We fabricate three surface patterning zinc oxide（ZnO） ordered arrays on glass substrates by using nanosphere lithography technique and dc magnetron sputtering technique. The crescent, tube and honeycomb surface morphologies of the samples are observed by scanning electron microscopy. The transmittance, fluorescence and confocal Raman spectra of the sample are measured. Obviously, when the angle between the plume and the substrate is 90°, the honeycomb arrays have a better transmission. Additionally, the PL intensity of honeycomb arrays is superior. With the increasing of the angle between the substrate and the sputtering plume, the fluorescence peak shows blue shift. The Raman peak located at438 cm^-1belongs to ZnO E2（high） mode, which corresponds to the characteristic band of the hexagonal wurtzite phase.The tube arrays have the best Raman spectrum intensity.
文摘New methods of synthetizing nonequidistant sparse antenna arrays based on the properties of magic squares are studied.The methods of construction and algorithms of synthesis of two-dimensional antennas based on them providing a high degreeof dilution and sufficiently small side radiation are proposed.The methods for construction of such antennas and their maincharacteristics are considered.
文摘On the basis of the second order solution of two-dimensional random gravity waves in finite uniform depth,which is rederived by a perturbation expansion method,the analytical expression of the second order spectrum is strictly deduced, and for infinite depth, the correct form of the kernel function is given for each octant do main.In fact,the present study improves and corrects the generally accepted results obtained by Tick
文摘A two-dimensional nonlinear sloshing problem is analyzed by means of the fully nonlinear theory and time domain second order theory of water waves. Liquid sloshing in a rectangular container Subjected to a horizontal excitation is simulated by the finite element method. Comparisons between the two theories are made based on their numerical results. It is found that good agreement is obtained for the case of small amplitude oscillation and obvious differences occur for large amplitude excitation. Even though, the second order solution can still exhibit typical nonlinear features of nonlinear wave and can be used instead of the fully nonlinear theory.
基金supported by the National Natural Science Foundation of China (Grant Nos. 50873085 and 21375116)a project funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD)
文摘The highly ordered silver-coated colloidal crystals arrays and macroporous silver films were derived through an electrostatics-induced adsorption effect using polystyrene(PS) as templates. Carboxyl-modified PS microspheres were prepared by emulsifier-free emulsion polymerization using methacrylic acid(MAA) as the functional monomer. PS microspheres were self-assembled into close packing colloidal crystals of facecentered cubic arrays to the substrate with vertical deposition method. These colloidal crystals were modified using dopamine(DA) to form poly-dopamine(PDA) during its oxidative polymerization. Through electrostatic interaction, the silver nanoparticles were deposited and adsorbed onto the surfaces of colloidal crystals templates by exposing [Ag(NH_3)_2]^+solution to infrared irradiation. Removal of the polymeric template by etching with methylbenzene solvent resulted in 3D ordered macroporous silver films. The structural and properties of the ordered silver-coated arrays and macroporous silver films were characterized by field emission scanning electron microscopy(FE-SEM), X-ray diffraction(XRD), UV-vis spectroscopy and surface-enhanced Raman spectroscopy(SERS). The results indicate that the prepared silver-coated arrays and macroporous silver films possess the features of ordered multilayer arrangement, uniformity and repeatability as well as an ideal SERS effect.
基金supported by the Natural Science Foundation of Tianjin(Grant No.24ZXZSSS00390)National Natural Science Foundation of China(Grant Nos.22121005,22071115 and 22401091),and grant from Frontiers Science Center for New Organic Matter.
文摘Fabricating interfacial layers with high lithiophilicity and rapid Li+transfer functionality is critical for dendrite-free lithium deposition in lithium-metal batteries(LMBs).Herein,a two-dimensional coordination network,NKU-2000,with ordered lithiophilic crown ether sites is applied as an interfacial layer to protect lithium metal anode.The Li||Li symmetrical cells with NKU-2000-based interfacial layer exhibit an ultralong cycle of 8500 h at 1 mA cm^(-2),and can stably cycle for 1700 h under a severe state of 10 mA cm^(-2)and 10 mAh cm^(-2).The corresponding LiFePO_(4)full cell achieves a long lifespan of 2000 cycles at 1 C with a capacity retention rate of 81.8%.A molecular-level mechanism study reveals that the lithiophilic crown ether sites reduce the Li+desolvation energy barrier,and the crown ether-based channels promote Li^(+)transfer kinetics.This work provides a facile coordination assembly approach of arranging uniformly distributed lithiophilic sites in efficient Li^(+)transfer channels of an interfacial layer for achieving dendrite-free lithium deposition in high-performance LMBs.
基金the National Natural Science Foundation of China (No. 21606021)Youth Scholars Program of Beijing Normal University (No. 2014NT07).
文摘Lithium-oxygen batteries have attracted considerable interest in the past a few years, because they have higher theoretical specific energy than Li-ion batteries. However, the available en ergy den sities of the Li-O2 batteries are much less than expected. It is particularly urgent to find catalyst with high activity. Herein, a series of Co3O4 with differe nt morphologies (ordered two-dimensio nal porous nano sheets, flowerlike and cuboidlike) were successfully prepared through facile hydrothermal and calcinatio n methods. Ordered two-dime nsional Co3O4 nano sheets show the best cycling stability. Detailed experimental results reveal that the superiority of the unique two-dimensional uniform porous structures is vital for Li-O2 batteries cathode catalysts. Due to the ordered structures with high surface areas and active sites, the catalysts indicate a high specific discharge capacity of about 10,417 mAh/g at a current density of 200 mA/g, and steadily cycle for more than 50 times with a limited capacity of 1,000 mAh/g.
基金supported by the National Natural Science Foundation of China under Grant No. G050104011004024the Specialized Research Fund for the Doctoral Program of Higher Education of China under Grant No. A0901040110018512026
文摘Surface plasmon resonance of noble metal nanoparticles leads to the optical absorption enhancement effects,which have great potential applications in solar cell.By using the general numerical method of discrete dipole approximation （DDA）,we study the absorption and scattering properties of two-dimensional square silver nanodisks （2D SSN） arrays on the single crystal silicon solar cell.Based on the effective reflective index model of the single crystal silicon solar cell,we investigate the optical enhancement absorption of light energy by varying the light incident direction,particle size,aspect ratio,and interparticle spacing of the silver nanodisks.The peak values and position of the optical extinction spectra of the 2D square arrays of noble metal nanodisks are obtained with the different array structures.
基金supported by the National Nature Science Foundation of China (60472101)President Award of ChineseAcademy of Sciences(O729031511).
文摘Adaptive broadband beamforraing is a key issue in array applications. The adaptive broadband beamformer with tapped delay line （TDL） structure for nonuniform linear array （NLA） is designed according to the rule of minimizing the beamformer＇s output power while keeping the distortionless response （DR） in the direction of desired signal and keeping the constant beamwidth （CB） with the prescribed sidelobe level over the whole operating band. This kind of beamforming problem can be solved with the interior-point method after being converted to the form of standard second order cone programming （SOCP）. The computer simulations are presented which illustrate the effectiveness of our beamformer.
文摘This paper gives a MUSIC signal DOA estimation algorithm based on the modified high-order cumulant matrix which is constructed by the recieved data and their conjugate rearrangements. When the snapshot number is limited, this algorithm can improve the signal DOA estimation performances obviously, and its computational complexity scarcely increases. Finally, some simulation results to verify the theoretical analyses are presented.
文摘随着电影对极致沉浸式视听体验的发展需求,沉浸式声场记录和重放技术日显重要。本文围绕电影音频制作技术中的声场记录和重放问题,介绍了基于球麦克风阵列的高阶高保真立体声(Higher Order Ambisonics,HOA)分析技术,并针对球麦克风阵列球谐分解中的低频噪声与高频混叠问题,以及双耳重放技术中的阶数受限问题,给出了相应解决方案,研究表明所提方案可为观众提供更真实、更具沉浸感的声场重放效果,提升了观影体验,在电影音频制作中具有广阔的应用前景。
基金supported by the National Science Foundation of China(NSFC)(Nos.61405029,91438108,and61231012)the Shanghai Aerospace Science and Technology(SAST)(No.2015087)
文摘A polarization-independent nonmechanical laser beam steering scheme is proposed to realize continuous two-dimensional（2 D） scanning with high efficiency, where the core components are two polarization-dependent devices, which are called liquid crystal optical phased arrays（LC-OPAs）. These two one-dimensional（1D） devices are orthogonally cascaded to work on the state of azimuthal and elevation steering, respectively. Properties of polarization independence as well as 2D beam steering are mathematically and experimentally verified with a good agreement. Based on the experimental setup, linearly polarized beams with different polarization angles are steered with high accuracy. The measured angular deviations are less than 5 μrad, which is on the same order of the accuracy of the measurement system. This polarization-independent 2 D laser beam steering scheme has potential application for nonmechanical laser communication, lidar, and other LC-based systems.
文摘In this paper, we report the growth and characteristics of titania nanotube arrays prepared by anodic oxidation and then annealed in an oxygen atmosphere at 500℃. The titania nanotube arrays presented high sensitivity to hydrogen gas. The crystalline phase of the samples was checked by X-ray diffraction (XRD). The differences in the nanotubes morphology attributed to the etched samples due to anodiza- tion potential, reaction time and the electrolyte concentration were analyzed by scanning electron mi- croscopy (SEM). The gas sensitive parameters of the samples were obtained from resistance, the re- sponse time and the recovery time at different temperatures.
