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Chinese Physics B 2019年第2期28卷 241-246页

作者： Li Jiang Ren-Gang Wan Department of Physics Changchun University of Science and Technology School of Physics and Information Technology Shaanxi Normal University

The absorption–dispersion properties of a microwave-driven five-level atom embedded in an isotropic photonic bandgap(PBG) have been studied. Due to the singular density of modes(DOM) in the isotropic PBG and the dynamically coherence induced by the coupling fields, modified reservoir-induced transparency and quantum interference-induced transparency emerge simultaneously. Their interaction leads to ultra-narrow spectral structure. As a result of closed-loop configuration, these features can be manipulated by the amplitudes and relative phase of the coherently driven fields. The position and width of PBG also have an influence on the spectra. The theoretical studies can provide us with more efficient methods to control the atomic absorption–dispersion properties, which have applications in optical switching and slow light.

关键词： isotropic photonic bandgap absorption–dispersion spectra phase and amplitude control ultranarrow spectral structure

amplitude of climatic changes in Qinghai-Tibetan Plateau

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Chinese Science Bulletin 2000年第13期45卷 1236-1243页

作者： YAO Tandong LIU Xiaodong WANG Ninglian SHI Yafeng Lanzhou Institute of Glaciology and Geocryology Chinese Academy of SciencesLanzhou 730000China Lanzhou Institute of Atmospheric Physics Over Highlands Chinese Academy of SciencesLanzhou 73000China

On the basis of ice core and meteorological data from the Qinghai-Tibetan (Q-l) Plateau, this article focuses on the discussion of the problems related to the sensitivity of temporal and spatial changes of the climate in high-altitude regions, particularly in the Q-T Plateau. The features of abrupt climatic changes of the past 100 ka, 2 000 a and recent years indicate that the amplitude of these changes in the Q-T Plateau was obviously larger than that in low-altitude regions. The scope of temperature change above 6 000 m in the Q-T Plateau between glacial and interglacial stages could reach over 10C℃, but only about 4℃ in low-elevation regions close to sea level. During the last 2 000 a, the amplitude of temperature changes at Guliya (over 6 000 m a.s.l.) in the Q-T Plateau reached 7℃, in comparison with 2℃ in eastern China at low altitude. In the present age, apparent differences of climatic warming have been observed in the Q-T Plateau, indicating that the warming in high-elevation regions is

关键词： Qinghai-Tibetan Plateau high elevation region abrupt climatic change amplitude of climatic change climatic sensitivity.

Propagation and amplitude Decay Mechanisms of Internal Solitary Waves

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China Ocean Engineering 2016年第6期30卷 979-991页

作者：王玲玲王春凌唐洪武陈红 State Key Laboratory of Hydrology- Water Resources and Hydraulic Engineering Nanjing 210008 China College of Water Conservancy and Hydropower Engineering Hohai University Nanjing 210029 China

In this paper, a modified dynamic coherent eddy model （DCEM） of large eddy simulation is applied to study internal solitary waves in a numerical flume. The model was verified by physical experiment and applied to investigate the potential influence factors on internal wave amplitude. In addition, we discussed the energy loss of internal solitary wave as well as hydrodynamics in the propagation. The results of our study show that （1） Step-depth is the most sensitive factor on wave amplitude for the ＂step-pool＂ internal wave generation method and the wave amplitudes obey a linear increase with step depth, and the increase rate is about 0.4. （2） Wave energy loss obeys a linear decrease with the propagation distance and its loss rate of large amplitude waves is smaller than that of small amplitude waves. （3） Loss of kinetic energy in wave valley is larger than that near the interface due to relative high fluctuating frequency. （4） Discovered boundary jet-flow can intensify the bottom shear, which might be one of the mechanisms of substance transportation, and the boundary layers of jet flows are easily influenced by the adjacent waves.

关键词： numerical wave flume internal solitary wave amplitude energy loss

Optimized analysis of ionospheric amplitude modulated heating parameters for excitation of very/extremely low frequency radiations

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Plasma Science and Technology 2019年第7期21卷 106-113页

作者： Jutao YANG Jianguo WANG Qingliang LI Haiqin CHE Shuji HAO School of Electronic and Information Engineering Xi’an Jiaotong UniversityXi’an 710049People’s Republic of China National Key Laboratory of Electromagnetic Environment China Research Institute of Radiowave PropagationQingdao 266107People’s Republic of China Northwest Institute of Nuclear Technology Xi’an 710024People’s Republic of China

It is now well known that amplitude modulated(AM) high frequency(HF) radio wave transmissions into the ionosphere can be used to generate very/extremely low frequency(VLF/ELF) radio waves using the so-called ‘electrojet antenna’. Duty cycle and heating frequency are analyzed and discussed with the lower-ionosphere modulated heating model, so as to improve the radiation efficiency of VLF/ELF waves in AM ionospheric heating experiments. Based on numerical simulation, the ranges of parametric selectivity in optimal duty cycle and heating frequency( fHF) are derived. The International Reference Ionosphere 2015(IRI-2015) model and two-parameter model are used to predict background electron density profiles, and optimized ranges of duty cycle for different density profiles are analyzed and compared. The influences of wave polarizations on optimal duty cycle are also discussed. It is shown that intensity of the VLF/ELF equivalent radiation source(M) firstly rises and then falls with the increase of duty cycle. When using the IRI model, M peaks at a duty cycle of 50%, optimally ranging from 40%-70%. For the two-parameter model case, an optimal duty cycle is 40% and the optimized ranges vary from 30%-60%. Heating with an X-mode polarization is more efficient than with the O-mode case in VLF/ELF wave generation. Nevertheless, an optimal duty cycle is almost independent of HF wave polarizations. To obtain better VLF/ELF generation, optional fHFmay be 0.8-0.9 times of foE for the O-mode heating and 0.75-0.85 times for the X-mode polarization case. Finally, the variations of these two parameters in different latitudes are discussed.

关键词： amplitude modulated heating parameter optimization duty cycle heating frequency

Wigner function for squeezed negative binomial state and evolution of density operator for amplitude decay

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Chinese Physics B 2019年第9期28卷 93-99页

作者： Heng-Yun Lv Ji-Suo Wang Xiao-Yan Zhang Meng-Yan Wu Bao-Long Liang Xiang-Guo Meng Shandong Provincial Key Laboratory of Optical Communication Science and Technology School of Physical Science and Information EngineeringLiaocheng UniversityLiaocheng 252059China Shandong Provincial Key Laboratory of Laser Polarization and Information Technology College of Physics and EngineeringQufu Normal UniversityQufu 273165China

Using the thermal-entangled state representation and the operator-ordering method, we investigate Wigner function(WF) for the squeezed negative binomial state(SNBS) and the analytical evolution law of density operator in the amplitude decay *** results show that the analytical WF is related to the square of the module of single-variable Hermite polynomials, which leads to a new two-variable special function and its generating function, and the parameters s and γplay opposite roles in the WF ***, after undergoing this channel, the initial pure SNBS evolves into a new mixed state related to two operator Hermite polynomials within normal ordering, and fully loses its nonclassicality and decays to vacuum at long decay time.

关键词： squeezed negative binomial state operator ordering Wigner function density-operator evolution amplitude decay

Entrainment range affected by the heterogeneity in the amplitude relaxation rate of suprachiasmatic nucleus neurons

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Chinese Physics B 2019年第1期28卷 663-668页

作者： Chang-Gui Gu Ping Wang Hui-Jie Yang Business School University of Shanghai for Science and Technology

Adaption of circadian rhythms in behavioral and physiological activities to the external light–dark cycle is achieved through the main clock, i.e., the suprachiasmatic nucleus(SCN) of the brain in mammals. It has been found that the SCN neurons differ in the amplitude relaxation rate, which represents the rigidity of the neurons to the external amplitude disturbance. Thus far, the appearance of that difference has not been explained. In the present study, an alternative explanation based on the Poincare′ model is given which takes into account the effect of the difference in the entrainment range of the SCN. Both our simulation results and theoretical analyses show that the largest entrainment range is obtained with suitable difference in the case that only a part of SCN neurons are sensitive to the light information. Our findings may give an alternative explanation for the appearance of that difference(heterogeneity) and shed light on the effects of the heterogeneity in the neuronal properties on the collective behaviors of the SCN neurons.

关键词： amplitude relaxation rate entrainment range heterogeneity

A time-sharing multi-channel pulse amplitude analyzer

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Nuclear Science and Techniques 2017年第4期28卷 91-96页

作者： Lian-Jun Jiang Xiang Zhou Tong-Yu Wu Ze-Jie Yin State Key Laboratory of Particle Detection and Electronics University of Science and Technology of China Department of Modern Physics University of Science and Technology of China

A conventional multi-channel pulse amplitude analyzer acquires single energy spectrum,but provides no information on its tendency with *** address the limitation,we propose a scheme of time-sharing multichannel pulse amplitude analyzer(TSMCA).A dual-port random access memory is divided into two storage spaces,one for current energy spectrum data acquisition and another for previous energy spectrum data *** two tasks can be performed simultaneously,and the time-related variation tendency of energy spectrum can be obtained.A prototype system of TSMCA is *** performs nicely,with maximum channel number of 4096 in capacity of 2^(32)/Ch,minimal time-sharing slice of 25 ms,the differential nonlinearity of <1.5%,and the integral nonlinearity of <0.3%.

关键词： Multi-channel pulse amplitude analyzer MCA Time-sharing ADC Dual-port RAM

Optimal estimation of the amplitude of signal with known frequency in the presence of thermal noise

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Chinese Physics B 2019年第10期28卷 274-281页

作者： Jie Luo Jun Ke Yi-Chuan Liu Xiang-Li Zhang Wei-Ming Yin Cheng-Gang Shao School of Mechanical Engineering and Electronic Information China University of GeosciencesWuhan 430074China MOE Key Laboratory of Fundamental Physical Quantities Measurement School of PhysicsHuazhong University of Science and Technology (HUST)Wuhan 430074China

In the torsion pendulum experiments, the thermal noise sets the most fundamental limit to the accurate estimation of the amplitude of the signal with known frequency. The variance of the conventional method can meet the limit only when the measurement time is much longer than the relaxation time of the pendulum. By using the maximum likelihood estimation and the equation-of-motion filter operator, we propose an optimal(minimum variance, unbiased) amplitude estimation method without limitation of the measurement time, where thermal fluctuation is the leading noise. While processing the experimental data tests of the Newtonian gravitational inverse square law, the variance of our method has been improved than before and the measurement time of determining the amplitude with this method has been reduced about half than before for the same uncertainty. These results are significant for the torsion experiment when the measurement time is limited.

关键词： optimal amplitude estimation thermal noise torsion pendulum measurement time

Prediction for Potential Landslide Zones Using Seismic amplitude in Liwan Gas Field, Northern South China Sea

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Journal of Ocean University of China 2017年第6期16卷 1035-1042页

作者： LI Xishuang LIU Baohua LIU Lejun ZHENG Jiewen ZHOU Songwang ZHOU Qingjie First Institute of Oceanography State Oceanic Administrator Qingdao 266061 P. R. China Laboratory for Marine Mineral Resources Qingdao National Laboratory for Marine Science and TechnologyQingdao 266071 P. R. China National Deep Sea Center Qingdao 266237 P. R. China Survey Center of China Oilfield Services Limited Tianjin 300451 P. R. China

The Liwan(Lw) gas field located in the northern slope of the South China Sea(SCS) is extremely complex for its seafloor topograghy, which is a huge challenge for the safety of subsea facilities. It is economically impractical to obtain parameters for risk assessment of slope stability through a large amount of sampling over the whole field. The linkage between soil shear strength and seabed peak amplitude derived from 2D/3D seismic data is helpful for understanding the regional slope-instability risk. In this paper, the relationships among seabed peak, acoustic impedance and shear strength of shallow soil in the study area were discussed based on statistical analysis results. We obtained a similar relationship to that obtained in other deep-water areas. There is a positive correlation between seabed peak amplitude and acoustic impedance and an exponential relationship between acoustic impedance and shear strength of sediment. The acoustic impedance is the key factor linking the seismic amplitude and shear strength. Infinite slope stability analysis results indicate the areas have a high potential of shallow landslide on slopes exceeding 15? when the thickness of loose sediments exceeds 8 m in the Lw gas field. Our prediction shows that they are mainly located in the heads and walls of submarine canyons.

关键词： seismic amplitude acoustic impedance shear strength slope stability analysis northern South China Sea

Adaptive Backstepping Control for Hypersonic Vehicles with Actuator amplitude and Rate Saturation

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Transactions of Nanjing University of Aeronautics and Astronautics 2019年第2期36卷 242-252页

作者： XIANG Kai DU Yanli ZHANG Peng LIN Haibing College of Astronautics Nanjing University of Aeronautics and Astronautics

This paper presents a constrained control strategy for the hypersonic vehicle with actuator amplitude,rate constraints and aerodynamic ***,a vehicle-actuator control model is derived in consideration of actuator dynamics properties ***,a nonlinear disturbance observer is designed to estimate the aerodynamic uncertainties,and then an adaptive backstepping control technique is adopted with a modified first-order-filter to eliminate the“explosion of terms”***,for handling the actuator amplitude and rate constraints,a novel auxiliary compensation system is constructed to generate quickly compensating signals to ensure tracking performance of command *** the Lyapunov stability proof,the proposed control scheme can enssure that the tracking errors converge to an arbitrarily small neighborhood around zero when the actuator constraints and aerodynamic uncertainties ***,numerical simulations are implemented to illustrate the effectiveness of the proposed control method.

关键词： hypersonic vehicle amplitude and rate saturation adaptive backstepping aerodynamic uncertainty