Almost all living organisms exhibit autonomic oscillatory activities,which are primarily generated by the rhythmic activities of their neural systems.Several nonlinear oscillator models have been proposed to elucidate...Almost all living organisms exhibit autonomic oscillatory activities,which are primarily generated by the rhythmic activities of their neural systems.Several nonlinear oscillator models have been proposed to elucidate these neural behaviors and subsequently applied to the domain of robot control.However,the oscillation patterns generated by these models are often unpredictable and need to be obtained through parameter search.This study introduces a mathematical model that can be used to analyze multiple neurons connected through fast inhibitory synapses.The characteristic of this oscillator is that its stationary point is stable,but the location of the stationary point changes with the system state.Only through reasonable topology and threshold parameter selection can the oscillation be sustained.This study analyzed the conditions for stable oscillation in two-neuron networks and three-neuron networks,and obtained the basic rules of the phase relationship of the oscillator network established by this model.In addition,this study also introduces synchronization mechanisms into the model to enable it to be synchronized with the sensing pulse.Finally,this study used these theories to establish a robot single leg joint angle generation system.The experimental results showed that the simulated robot could achieve synchronization with human motion,and had better control effects compared to traditional oscillators.展开更多
We present an efficient approach to solve multi-dimensional time-dependent Schr?dinger equation(TDSE)in an intense laser field.In this approach,each spatial degree of freedom is treated as a distinguishable quasi-part...We present an efficient approach to solve multi-dimensional time-dependent Schr?dinger equation(TDSE)in an intense laser field.In this approach,each spatial degree of freedom is treated as a distinguishable quasi-particle.The non-separable Coulomb potential is regarded as a two-body operator between different quasi-particles.The time-dependent variational principle is used to derive the equations of motion.Then the high-order multi-dimensional problem is broken down into several lower-order coupled equations,which can be efficiently solved.As a demonstration,we apply this method to solve the two-dimensional TDSE.The accuracy is tested by comparing the direct solutions of TDSE using several examples such as the strong-field ionization and the high harmonic generation.The results show that the present method is much more computationally efficient than the conventional one without sacrificing accuracy.The present method can be straightforwardly extended to three-dimensional problems.Our study provides a flexible method to investigate the laser-atom interaction in the nonperturbative regime.展开更多
In DEM generation using interferometric synthetic aperture radar(InSAR),the ground control points(GCPs)for refinement and reflattening are usually selected by manual selection,field surveying,GPS points and existing b...In DEM generation using interferometric synthetic aperture radar(InSAR),the ground control points(GCPs)for refinement and reflattening are usually selected by manual selection,field surveying,GPS points and existing basemaps,which may not be completely suitable for consequent processes.We proposed a new method(auto-PS-GCP)of GCP selection based on permanent scatterers,which automatically defines the thresholds for the coherence,amplitude,and amplitude dispersion index to select permanent scatterer as the GCPs.The GCP thinning(auto-PS-GCP-Thin)was further conducted considering the point density,distances among points and terrain conditions.We used a three-stage assessment that includes:(1)phase stability and intensity of the GCPs,(2)RMSEs of the elevations between GCPs and homonymous points in the reference DEM,and(3)generated DEM accuracy.Three areas respectively in the plain,hilly and mountainous regions were selected to verify the proposed methods.The assessment using both SRTM DEM andICESat-2 points shows that the DEM accuracy of auto-PS-GCP-Thin was improved by 20%∼30%for different areas compared to the manual,where the best DEM accuracy of 4.71 m was found in the plain area.It is concluded that the proposed methods are effective and reliable in various areas with different terrain conditions.展开更多
We present the recent new developments of time-dependent Schrödinger equation and time-dependent density-functional theory for accurate and efficient treatment of the electronic structure and time-dependent quant...We present the recent new developments of time-dependent Schrödinger equation and time-dependent density-functional theory for accurate and efficient treatment of the electronic structure and time-dependent quantum dynamics of many-electron atomic and molecular systems in intense laser fields.We extend time-dependent generalized pseudospectral(TDGPS)numerical method developed for time-dependent wave equations in multielectron systems.The TDGPS method allows us to obtain highly accurate time-dependent wave functions with the use of only a modest number of spatial grid point for complex quantum dynamical calculations.The usefulness of these procedures is illustrated by a few case studies of atomic and molecular processes of current interests in intense laser fields,including multiphoton ionization,above-threshold ionization,high-order harmonic generation,attosecond pulse generation,and quantum dynamical processes related to multielectron effects.We conclude this paper with some open questions and perspectives of multiphoton quantum dynamics of many-electron atomic and molecular systems in intense laser fields.展开更多
Monochromatization of high-harmonic sources has opened fascinating perspectives regarding time-resolved photoemission from all phases of matter.Such studies have invariably involved the use of spectral filters or spec...Monochromatization of high-harmonic sources has opened fascinating perspectives regarding time-resolved photoemission from all phases of matter.Such studies have invariably involved the use of spectral filters or spectrally dispersive optical components that are inherently lossy and technically complex.Here we present a new technique for the spectral selection of near-threshold harmonics and their spatial separation from the driving beams without any optical elements.We discover the existence of a narrow phase-matching gate resulting from the combination of the non-collinear generation geometry in an extended medium,atomic resonances and absorption.Our technique offers a filter contrast of up to 104 for the selected harmonics against the adjacent ones and offers multiple temporally synchronized beamlets in a single unified scheme.We demonstrate the selective generation of 133,80 or 56 nm femtosecond pulses from a 400-nm driver,which is specific to the target gas.These results open new pathways towards phase-sensitive multi-pulse spectroscopy in the vacuum-and extreme-ultraviolet,and frequencyselective output coupling from enhancement cavities.展开更多
We present an experimental study on low-threshold broadband spectrum generation mainly due to the amplirfication of the cascaded stimulated Raman scattering （SRS） effect in a four-stage fiber master oscillator power...We present an experimental study on low-threshold broadband spectrum generation mainly due to the amplirfication of the cascaded stimulated Raman scattering （SRS） effect in a four-stage fiber master oscillator power amplifier system. The cascaded SRS is achieved by using a long passive fiber pumped by a pulsed fiber laser cen： tered at wavelength 1064 nm. The amplified spontaneous emission during the amplification process is efficiently suppressed by cutting the length of the passive fiber and by using a double-clad ytterbium-doped fiber amplifier. The generated broadband spectrum spans from 960nm to 1700nm with maximum average output 13.6 W and average spectral power density approximately 17. 7 mW/nm.展开更多
The article deals with the methodology of pseudorandom data analysis. As a mathematical tool for carrying out the research the extreme value theory was used that creates one of the directions in mathematical statistic...The article deals with the methodology of pseudorandom data analysis. As a mathematical tool for carrying out the research the extreme value theory was used that creates one of the directions in mathematical statistics, and is related to investigating the extreme deviations from the median values in probability distributions. Also, the methods for estimating unknown parameters and algorithm of random-number generation are discussed. The models of treatment the extreme values are constructed which are based on machine generated sample and approach is proposed for their future application for constructing forecasting models.展开更多
经实验测定,草地螟(Loxostege sticticalis L. )各虫态的发育起点温度:卵为14.3℃、幼虫为12.7℃、蛹为11.6℃、成虫为11.0℃;有效积温:卵为30.5日度、幼虫为190.7日度、蛹为158.3日度、成虫为96.7日度。全世代的发育起点温度为10.5℃,...经实验测定,草地螟(Loxostege sticticalis L. )各虫态的发育起点温度:卵为14.3℃、幼虫为12.7℃、蛹为11.6℃、成虫为11.0℃;有效积温:卵为30.5日度、幼虫为190.7日度、蛹为158.3日度、成虫为96.7日度。全世代的发育起点温度为10.5℃,有效积温为531.2日度。虽然草地螟各虫态的理论发育起点温度和实测值尚有一定差异,但根据上述结果推算的发生世代数目和实际发生世代数目基本一致。根据对草地螟发生地区的有效积温计算和实际观察记载,草地螟在我国的发生世代数目表现为由南到北递减的趋势。在年等温线0℃以北地区每年发生1代,年等温线0—8℃地区年生2—3代,年等温线8—12℃地区年生3—4代。草地螟在我国的主要为害区是2—3代区,主要为害世代是第一代。展开更多
基金supported in part by the National Nature Science Foudation under Grant 62333023in part by the Key Research and Development Program of Zhejiang Province under Grant 2021C03050in part by the Scientific Research Project of Agriculture and Social Development of Hangzhou under Grant 20212013B11.
文摘Almost all living organisms exhibit autonomic oscillatory activities,which are primarily generated by the rhythmic activities of their neural systems.Several nonlinear oscillator models have been proposed to elucidate these neural behaviors and subsequently applied to the domain of robot control.However,the oscillation patterns generated by these models are often unpredictable and need to be obtained through parameter search.This study introduces a mathematical model that can be used to analyze multiple neurons connected through fast inhibitory synapses.The characteristic of this oscillator is that its stationary point is stable,but the location of the stationary point changes with the system state.Only through reasonable topology and threshold parameter selection can the oscillation be sustained.This study analyzed the conditions for stable oscillation in two-neuron networks and three-neuron networks,and obtained the basic rules of the phase relationship of the oscillator network established by this model.In addition,this study also introduces synchronization mechanisms into the model to enable it to be synchronized with the sensing pulse.Finally,this study used these theories to establish a robot single leg joint angle generation system.The experimental results showed that the simulated robot could achieve synchronization with human motion,and had better control effects compared to traditional oscillators.
基金Project supported by the National Natural Science Foundation of China (Grant Nos.12204545 and 12274294)the Program for NUE independent research and development。
文摘We present an efficient approach to solve multi-dimensional time-dependent Schr?dinger equation(TDSE)in an intense laser field.In this approach,each spatial degree of freedom is treated as a distinguishable quasi-particle.The non-separable Coulomb potential is regarded as a two-body operator between different quasi-particles.The time-dependent variational principle is used to derive the equations of motion.Then the high-order multi-dimensional problem is broken down into several lower-order coupled equations,which can be efficiently solved.As a demonstration,we apply this method to solve the two-dimensional TDSE.The accuracy is tested by comparing the direct solutions of TDSE using several examples such as the strong-field ionization and the high harmonic generation.The results show that the present method is much more computationally efficient than the conventional one without sacrificing accuracy.The present method can be straightforwardly extended to three-dimensional problems.Our study provides a flexible method to investigate the laser-atom interaction in the nonperturbative regime.
基金Supported by the National Key R&D Program of China(2021YFB3900105-2)the National Natural Science Foundation of China(42071371).
文摘In DEM generation using interferometric synthetic aperture radar(InSAR),the ground control points(GCPs)for refinement and reflattening are usually selected by manual selection,field surveying,GPS points and existing basemaps,which may not be completely suitable for consequent processes.We proposed a new method(auto-PS-GCP)of GCP selection based on permanent scatterers,which automatically defines the thresholds for the coherence,amplitude,and amplitude dispersion index to select permanent scatterer as the GCPs.The GCP thinning(auto-PS-GCP-Thin)was further conducted considering the point density,distances among points and terrain conditions.We used a three-stage assessment that includes:(1)phase stability and intensity of the GCPs,(2)RMSEs of the elevations between GCPs and homonymous points in the reference DEM,and(3)generated DEM accuracy.Three areas respectively in the plain,hilly and mountainous regions were selected to verify the proposed methods.The assessment using both SRTM DEM andICESat-2 points shows that the DEM accuracy of auto-PS-GCP-Thin was improved by 20%∼30%for different areas compared to the manual,where the best DEM accuracy of 4.71 m was found in the plain area.It is concluded that the proposed methods are effective and reliable in various areas with different terrain conditions.
基金the National Natural Science Foundation of China(Grant Nos.11674268 and 11764038)the Natural Science Foundation of Guangdong Province,China(Grant No.2020A1515010927)Department of Education of Guangdong Province,China(Grant Nos.2018KCXTD011 and 2019KTSCX037).
文摘We present the recent new developments of time-dependent Schrödinger equation and time-dependent density-functional theory for accurate and efficient treatment of the electronic structure and time-dependent quantum dynamics of many-electron atomic and molecular systems in intense laser fields.We extend time-dependent generalized pseudospectral(TDGPS)numerical method developed for time-dependent wave equations in multielectron systems.The TDGPS method allows us to obtain highly accurate time-dependent wave functions with the use of only a modest number of spatial grid point for complex quantum dynamical calculations.The usefulness of these procedures is illustrated by a few case studies of atomic and molecular processes of current interests in intense laser fields,including multiphoton ionization,above-threshold ionization,high-order harmonic generation,attosecond pulse generation,and quantum dynamical processes related to multielectron effects.We conclude this paper with some open questions and perspectives of multiphoton quantum dynamics of many-electron atomic and molecular systems in intense laser fields.
基金support from a starting grant(project No.307270-ATTOSCOPE)of the European Research Councilthe Swiss National Science Foundation via the National Centre of Competence in Research Molecular Ultrafast Science and Technology.
文摘Monochromatization of high-harmonic sources has opened fascinating perspectives regarding time-resolved photoemission from all phases of matter.Such studies have invariably involved the use of spectral filters or spectrally dispersive optical components that are inherently lossy and technically complex.Here we present a new technique for the spectral selection of near-threshold harmonics and their spatial separation from the driving beams without any optical elements.We discover the existence of a narrow phase-matching gate resulting from the combination of the non-collinear generation geometry in an extended medium,atomic resonances and absorption.Our technique offers a filter contrast of up to 104 for the selected harmonics against the adjacent ones and offers multiple temporally synchronized beamlets in a single unified scheme.We demonstrate the selective generation of 133,80 or 56 nm femtosecond pulses from a 400-nm driver,which is specific to the target gas.These results open new pathways towards phase-sensitive multi-pulse spectroscopy in the vacuum-and extreme-ultraviolet,and frequencyselective output coupling from enhancement cavities.
基金Supported by the National Natural Science Foundation of China under Grant No 11404404the Outstanding Youth Fund Project of Hunan Provincethe Fund of Innovation of National University of Defense Technology under Grant No B120701
文摘We present an experimental study on low-threshold broadband spectrum generation mainly due to the amplirfication of the cascaded stimulated Raman scattering （SRS） effect in a four-stage fiber master oscillator power amplifier system. The cascaded SRS is achieved by using a long passive fiber pumped by a pulsed fiber laser cen： tered at wavelength 1064 nm. The amplified spontaneous emission during the amplification process is efficiently suppressed by cutting the length of the passive fiber and by using a double-clad ytterbium-doped fiber amplifier. The generated broadband spectrum spans from 960nm to 1700nm with maximum average output 13.6 W and average spectral power density approximately 17. 7 mW/nm.
文摘The article deals with the methodology of pseudorandom data analysis. As a mathematical tool for carrying out the research the extreme value theory was used that creates one of the directions in mathematical statistics, and is related to investigating the extreme deviations from the median values in probability distributions. Also, the methods for estimating unknown parameters and algorithm of random-number generation are discussed. The models of treatment the extreme values are constructed which are based on machine generated sample and approach is proposed for their future application for constructing forecasting models.
文摘经实验测定,草地螟(Loxostege sticticalis L. )各虫态的发育起点温度:卵为14.3℃、幼虫为12.7℃、蛹为11.6℃、成虫为11.0℃;有效积温:卵为30.5日度、幼虫为190.7日度、蛹为158.3日度、成虫为96.7日度。全世代的发育起点温度为10.5℃,有效积温为531.2日度。虽然草地螟各虫态的理论发育起点温度和实测值尚有一定差异,但根据上述结果推算的发生世代数目和实际发生世代数目基本一致。根据对草地螟发生地区的有效积温计算和实际观察记载,草地螟在我国的发生世代数目表现为由南到北递减的趋势。在年等温线0℃以北地区每年发生1代,年等温线0—8℃地区年生2—3代,年等温线8—12℃地区年生3—4代。草地螟在我国的主要为害区是2—3代区,主要为害世代是第一代。
