Vol. 49, No. 1 (2000)

Properties of the Kink Pair in the Presence of External Force and Dam ping in Hydrogen Bonded Molecular Systems
Cao Wan-Qiang, Cheng Yuan-Fa
2000, 49 (1): 1-4. doi: 10.7498/aps.49.1
Abstract +
Using vibrator model of the two-component soliton  we investigate the motion of a kink pair consisting of kinks in different sublattices in the presence of exte rnal force and damping in hydrogen bonded molecular systems. The influence on th e mobility of the kink pair due to the motion of heavy ion and the nucleation ra te of the kink pair are discussed. We give the mobility and mean nucleation rate of a kink pair.
Indecomposable and Irreducible Representations of the SPL(2,1) Superal gebra
Chen Yong-qing
2000, 49 (1): 5-10. doi: 10.7498/aps.49.5
Abstract +
Using inhomogeneous boson-ferimon realization the indecomposable and irreducibl e representations of the SPL(2 1) are studied on subspace and quotient spaces of the universal enveloping algebra of Heisenberg-weyl superalgebra.All the finit e dimensional irreducible representations of the SPL(2 1) are given.
Time Evolution and Berry Phases of a Time-Dependent Oscillator in Fin ite-Dimensional Hilbert Space
Li Zhi-jian, Cheng Jian-gang, Liang Jiu-qing
2000, 49 (1): 11-16. doi: 10.7498/aps.49.11
Abstract +
In this paper we investigate the time evolution of a time-dependent oscillator in finite-dimensional Hilbert space. By performing appropriate time-dependent gauge transformation closed formulas for the time evolution of quantum states an d Berry phases are obtained. Finally we discuss the influence of the driving te rm in the Hamiltonian on the squeezed feature of coherent states.
Matrix Elements of Arbitrary Exponential Quadratic Operator in Multi- Dimensional Phase Space
Xu Xiu-wei, Zhao Ji-de, Ren Ting-Qi
2000, 49 (1): 17-19. doi: 10.7498/aps.49.17
Abstract +
Utilizing the normal and antinomal product representative of exponential quadrat ic operator in multi-dimensional phase space we give the exact expressions of matrix element for arbitrary exponential quadratic operator. Thus we derive the partition function and wave function of the system of quadratic Hamiltonian with out the knowledge of energy spectrum and eigenfunctions.
The Synchronization of Strange Nonchaotic Systems Based on Contraction Maps
Liu Jian-bo, Ye Chun-fei, Zhang Shu-jing
2000, 49 (1): 20-23. doi: 10.7498/aps.49.20
Abstract +
In this paper a new method of synchronization of strange nonchaotic systems is proposed. Strange nonchaotic attractors are obtained from a chaotic system.driven by another chao tic system. Because the Lyapunov exponent of the strange nonchaotic attractor is negative it can sup presses the sensitive dependence on initial conditions of the chaotic system. In order to synchronize the strange nonchaotic system-contraction map is used to synchronize the chaotic driving system. Simul ations indicate that this method can synchronize fast be robust to nose-easily be implemented and c an be used in the field of chaotic secure communication. 
The Largest Lyapunov Exponent of Coupled Map Lattice Systems   
Shi Peng-liang, Hu Gang, Xu Li-mei
2000, 49 (1): 24-29. doi: 10.7498/aps.49.24
Abstract +
Based on the investigation of the largest Lyapunov exponent of coupled map latti ce systems  it is found that in the parameter region of chaos  if the system is large enough and the coupling coefficient is neither too small nor too large  th e largest Lyapunov exponent of the system has a plateau which does not vary wit h the size and the coupling coefficient. The physical meaning of this flat pla teau is discussed.
Control of Chaotic Lorenz System to Approach any Desired Targets With Feedback Functions
Tang Guo-ning, Luo Xiao-shu, Kon g Ling-jiang
2000, 49 (1): 30-32. doi: 10.7498/aps.49.30
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This paper investigates the methods for controlling chaos in the Lorenz system with nonlinear feedback functions. Feedback functions and results of controlling-chaos are presented through theoretical analysis. The results of theory and num erical calculations indicate that the trajectories of a chaotic system can be co ntrolled to approach the target periodic orbits or points by feedback functions.
Impulsive Synchronization of Nonautonomous Chaotic Systems 
Yang Lin-bao, Yang Tao
2000, 49 (1): 33-37. doi: 10.7498/aps.49.33
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In this paper-the practical stability of impulsive synchronization between two-nonautonomous chaotic systems is studied. This practical stability is equivalent to that of the origin of the synchronization error system. We present the crite ria for the practical stability of the origin of the synchronization error syste m based on the theory of impulsive differential equation. We also provide the theoretical results on the range of synchronization errors. Numerical experimental-results are given to compare with theoretical results.
Phase-Induced Biaxiality in Cholesteric Liquid Crystals
Yang Guo-chen, Han Bing
2000, 49 (1): 38-44. doi: 10.7498/aps.49.38
Abstract +
The liquid cell theory can be successfully applied to cholesteric liquid crystals. Using the statistical methods and defining an order parameter tensor  we ded uce the distribution function and the Helmholtz free energy  which is the functi on of the order parameter tensor and its derivatives. The expression of the free e nergy we obtain has the same form with of the Landau theory. In a local coordina te system the long-range orientational parameter Sand the phase-induced biaxiality order parameter are defined. By minimizing the Hemholtz free energy  we numerically calculate the temperature dependence of Sand .The r esults agree with the experiment.
Study on Microstructure Evolution and Liquid-Solid Correlation of Pur e Aluminum Melts 
Wang Li, Li Hui, Bian Xiu-fang, Sun Min-hua, Liu Xiang-fa, Liu Hong-bo, Chen Kui-ying
2000, 49 (1): 45-48. doi: 10.7498/aps.49.45
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The molecular dynamics simulations have been performed on microstructure and tra n sfer mechanism of liquid Al. The pair distributed function has been attained at different temperatures and cooling rates by means of tight-binding potential. T he proportions of small atom groups of different types have been analyzed by ado pting bond pair index method. The result indicates that if the cooling rate is l ow  crystals will be formed otherwise amorphism will occur under relatively hi gh cooling rate. When the liquid Al forms crystal the bond pairs 1421 1422 play an important role  while the pairs 1551 1541 have the close connection with the formation of amorphism.
On Stochastic Bifurcation Behavior of the Atom Movement at the Tip of a Crack in Fatigue Damage System
Xiong Jun-jiang, Gao Zhen-tong, Liu Xian-bin, Sun Xun-fang
2000, 49 (1): 49-53. doi: 10.7498/aps.49.49
Abstract +
By virtue of the stochastic bifurcation theory the transition of the atom moveme nt at a crack tip in fatigue damage system is investigated.Using the singular po int theory of one-dimensional diffusion process and the stochastic averaging ap proach of energy envelope a micro-model to describe the atom movement at the cr ack tip in homoclinic bifurcation fatigue damage system which is in the presence of stochastic perturbation is established.After the study on the characteristic of the diffusion exponent the drift exponent and the character exponent of the fatigue damage diffusion process on singular boundary the bifurcation behavior o f a homoclinic bifurcation fatigue damage system which is in the presence of par ametric white noise is examined.
Discussion of the Boundary Condition For Electromagnetic Scattering b y Spheroidal Particles
Han Yi-ping, Wu Zhen-sen
2000, 49 (1): 57-60. doi: 10.7498/aps.49.57
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Theoretical expression of the boundary condition for electromagnetic scattering by spheroidal particles is given by virtue of the method presented by Shoji Asan o and Giichi Yamamoto.The incorrect coefficients of expansions given by Shojis has been corrected.
Quantitative Study of Improvements of the Imaging Contrast and Imaging Range by the Polarization Technique
Cao Nian-wen, Liu Wen-qing, Zhang Yu-jun
2000, 49 (1): 61-66. doi: 10.7498/aps.49.61
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The relation between the polarization technique and the enhance for the image contrast and the imaging range has been reported in this paper.The equati on expressing the image contrast and the imaging range is calculated and the exp erimental data is acquired.The experimental data agree with the calculated resu lt.It is shown quantitatively that the polarization technique improves the image contrast and imaging range greatly.
Dynamics of Two-Mode SU(2) Coherent States Interacting With Two C onpled Atoms
Peng Jin-sheng, Tian Yong-hong
2000, 49 (1): 67-73. doi: 10.7498/aps.49.67
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The dynamic behavior of atoms and nonclassical properties of the two-mode field in the system of nondegenerate two-photon interacting of SU(2) coherents tates with two atoms are studied. Influences of the total photon number the par tition parameter and the dipole-dipole interaction on the atomic dynamic behav ior and the quantum statistics properties of the two-mode field are discussed.
Displaced Excited Squeezed Vacuum States and Their Propertities
Sun Zhi-hu, Fan Hong-yi
2000, 49 (1): 74-79. doi: 10.7498/aps.49.74
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We introduce the states D(z)a\+\{+\+m\}S(r)|0〉 and examine their properties . Such states are checked to be complete vectors via the IWOP (Integration W ithin an Ordered Product of operators) technique. We find larger-scale macrosco pic oscillations of photon distribution after the squeezed vacuum states being e xcited and displaced. On contrary to the bunching photons of the squeezed vacuum states  as the displacing parameter |z| and the excitation number m are both small  photons coherence can exhibit antibunching effect. The quasi-proba bility distribution functions (Husimi Q(  醆+*) function and Wigner W(q  p) function) are derived and their dependences on the three parameters (z m  r) are discussed. The Wigner function obviously displays their nonclassical fe ature.
Experimental Research on Generation of Intensity Squeezed Light at 532 ?nm by SHG
Zhang Kuan-shou, Zhang Jing, Xie Chang-de, Peng Kun-chi
2000, 49 (1): 80-84. doi: 10.7498/aps.49.80
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Considering the noise characteristics of the pump source the noise spectra of ou tput harmonic field from the singly resonant frequency doubler is derived by mea ns of the motion equations for SHG.The intensity noise squeezing of 20% has been measured from the stable SH wave output.(It is in accordence with the squeezing of 30% if the efficiency of detection system is taken into account).The maximum squeezing measured experimentally is in agreement with the theoretical predicti ons.
Theoretic and Experimental Study on Large-Frequency-Difference Side -Mode Injection Locking of High Power Semiconductor Lasers for Laser Cooling 
Wang Xiao-hui, Chen Xu-zong, Hou Ji-dong, Yang Dong-hai, Wang Yi-qiu
2000, 49 (1): 85-93. doi: 10.7498/aps.49.85
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The high power semiconductor lasers were side-mode injection locked with freque ncy difference 1300?GHz with respect to its free working frequency using inject ion locking technique.The transfer of coherent characteristic between the master laser and slave laser was studied experimentally in detail by using saturated a bsorption spectra and optical heterodyne technique.The relation of locking bandw idth versus the ratio of injection power and the mode building process of inject ion locking were measured and the experimental locking bandwidth agreed with the side-mode locking bandwidth obtained by multi-mode rate equation followed by injection term.The threshold injection light power for realizing side-mode inje ction locking was calculated theortically and tested by experiment.
Measurement and Analysis on Shock Wave Driven by X-ray Radiation
Jiang Shao-en, Zheng Zhi-jian, Li Wen-hong, Ding Yao-nan, Sun Ke-xu, Liu Yong-gang, Jiang Xiao-hua
2000, 49 (1): 94-97. doi: 10.7498/aps.49.94
Abstract +
CH foam material is filled in the cavities in order to improve planar degree of shock wave driven by X-ray radiation.Wedge-shaped aluminum samples are used to measure time-space streaking images of optical signals from the shock wave.And then the velocity and pressure of the shock wave is obtained.The radiation temp erature is obtained by using the scaled relations between veloctiy of shock wave and radiation temperature.
Measurment of Soft X-ray Spectrum by Filter Difference Method
Sun Ke-xu, Jiang Shao-en, Huang Tian-xuan, Yi Rong- qing, Cui Yan-li, Wang Hong-bin, Chen Jiu-sen, Yu Rui-zhen, Ding Yao-nan, Ding Yong-kun, Tang Dao-yuan, Wen Shu-huai
2000, 49 (1): 98-101. doi: 10.7498/aps.49.98
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The method of filter difference which is used to measure X-ray spectrum radiate d from laser-produced plasma has been studied in this paper.The basic principle of the method of filter difference is introduced and the calculated and measure d results of filter difference pair are given.The absolute soft X-ray spectra f rom laser plasma have been measured.Finally the errors of measured spectrum inte nsity are analysed and estimated.
Studies on Many-Body Interactions and Molecular Dynamics Simulations for the Hugoniot Curves of Liquid Argon
Yang Chuan-lu, Wang Fan- hou, Li Xi-jun, Jing Fu-qian
2000, 49 (1): 114-118. doi: 10.7498/aps.49.114
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Because of the fundamental nature of condensed rare gases their potentials and e quations of state have been studied extensively in recent years.In the present w ork based on ab initio calculations on many-body interactions the MSVⅢ potenti al proposed by Parson et al.for argon system has been modified and the molec ula r dynamics method is employed to calculate the Hugoniot curve for liquid argon s ystem.Comparisons are performed between theoretical Hugoniot curve and the exper imental measurements.This demonstrates that the coincidence degree between the t heoretical and the experimental results is significantly improved.
Magnetoresistance Relaxation Effect for La2/3Ca1/3Mn1- xCuxO3(x=0.15) System in Liquid-Helium Temperature Regime
Yuan Song-liu, Li Guang, Jiang Yong, Sun Xia, Tang Pang, Huang Zhen, Wang Sheng
2000, 49 (1): 124-127. doi: 10.7498/aps.49.124
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The time dependence of resistance under certain magnetic fields in liquid-heliu m temperature regime for single-phase polycrystalline La2/3Ca1/3Mn1-xCuxO-3(x=0.15) have been experimentally studied.It was found that the behavior does not observe the logarithm lawR∝ln t but p resents an exponent-decaying dependence instead.A possible origin for this expo nent-decaying resistance relaxation was discussed in the paper.It was pointed out that the behavior is related to magnetic impurities that are introduced into the system by Cu-doping on Mn sites.
Neural Networks Models on Threshold Electric Field of Field Emission
Yu Li-juan, Zhu Chang-chun
2000, 49 (1): 170-173. doi: 10.7498/aps.49.170
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This article uses the model of BP neural networks proposes the forecasting model of neural networks in combination with the characteristics of field emission co ld cathode and applies the data of threshold electric field of diamond thin film to test.The results show that the relative error of the model is within 6\^6% a nd the model possesses good forecast characteristics through simulation and imi tation.
Effect of High-Temperature Treatment on the Crystallization of CNx Thin Films
Xiao Xing-cheng, Jiang Wei-hui, Tian Jing-fen, Song Li-xing, Hu Xing-fang
2000, 49 (1): 173-176. doi: 10.7498/aps.49.173
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The amorphous carbon nitride films were prepared by dc magnetron sputtering first and then were heat-treated at high temperature.DTA XRD Auger spectroscopy wer e used to study the difference of composition structure before and after heat-t reatment.The results showed that crystallization occurred at 1186℃.Heat-treatm ent can induce the crystallization of carbon nitride and the diffraction peaks a ppeared in the XRD pattern.The results of Auger spectroscopy also showed that th ere existed SiCN-riched area and the content of N decreased.