Table of contents

15 February 2001, Volume 10 Issue 2 Previous issue    Next issue

GENERAL

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HIGHER DIMENSIONAL PAINLEVé INTEGRABLE MODELS FROM THE REAL NONLINEAR EVOLUTION EQUATIONS Ruan Hang-yu (阮航宇), Chen Yi-xin (陈一新) Chinese Physics, 2001, 10 (2):  87-96.  DOI: 10.1088/1009-1963/10/2/301 Abstract ( 968 )   PDF (269KB) ( 456 )   A conformal invariant asymptotic expansion approach to solve any nonlinear integrable and nonintegrable models with any dimension is proposed. Many new Painlevé integrable models with the same dimension can be obtained at the same time. Taking the (2+1)-dimensional KdV-Burgers (KdVB) equation, (3+1)-dimensional Zabolotskaya-Khokhlov and Kudomtsev-Petviashvili (ZKKP) equation as concrete examples, we obtain some new higher dimensional conformal invariant models with Painlevé property and the approximate solutions of these models. In certain special cases, some of the approximate solutions become exact.

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ADAPTIVE NONLINEAR FEEDBACK CONTROL OF CHAOTIC SYSTEMS BASED ON REDUCED PARAMETER QUADRATIC PREDICTORS Zhang Jia-shu (张家树), Wan Ji-hong (万继宏), Xiao Xian-ci (肖先赐) Chinese Physics, 2001, 10 (2):  97-102.  DOI: 10.1088/1009-1963/10/2/302 Abstract ( 1143 )   PDF (239KB) ( 826 )   An adaptive nonlinear feedback-control method is proposed to control continuous-time chaotic dynamical systems, where the adaptive nonlinear controller acts on only one-dimensional error signal between the desired state and the observed chaotic state of a system. The reduced parameter adaptive quadratic predictor used in adaptive feedback cancellation of the nonlinear terms can control the system to any desired state. Computer simulation results on the Lorenz system are shown to demonstrate the effectiveness of this feedback-control method.

THE PHYSICS OF ELEMENTARY PARTICLES AND FIELDS

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SUPERSYMMETRIC SU(1|2) GAUDIN MODEL Cao Jun-peng (曹俊鹏), Hou Bo-yu (侯伯宇), Yue Rui-hong (岳瑞宏) Chinese Physics, 2001, 10 (2):  103-108.  DOI: 10.1088/1009-1963/10/2/303 Abstract ( 1011 )   PDF (259KB) ( 454 )   In this paper, we propose a supersymmetric SU(1|2) Gaudin model and have derived its eigenvalues. We also present the well-defined eigenstates through the quasi-classical limit of the eigenstates in the supersymmetric t-J model.

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BETHE ANSATZ FOR SUPERSYMMETRIC MODEL WITH Uq[osp(1|2)] SYMMETRY Yang Wen-li (杨文力) Chinese Physics, 2001, 10 (2):  109-112.  DOI: 10.1088/1009-1963/10/2/304 Abstract ( 1040 )   PDF (200KB) ( 519 )   Using the algebraic Bethe ansatz method, we obtain the eigenvalues of the transfer matrix of the supersymmetric model with Uq[osp(1|2)] symmetry under periodic boundary and twisted boundary condition.

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EXACT SOLUTION FOR EXTENDED ESSLER--KOREPIN--SCHOUTENS MODEL WITH OPEN BOUNDARY CONDITIONS Li Guang-liang (李广良), Yue Rui-hong (岳瑞宏), Shi Kang-jie (石康杰), Hou Bo-yu (侯伯宇) Chinese Physics, 2001, 10 (2):  113-116.  DOI: 10.1088/1009-1963/10/2/305 Abstract ( 960 )   PDF (212KB) ( 388 )   The eigenvalue of the transfer matrix is obtained for the extended Essler-Korepin-Schoutens model with open boundary conditions. The energy of the system and the Bethe equations of the model are given also.

NUCLEAR PHYSICS

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LEVEL DENSITY AND FINITE-TEMPERATURE SPECIFIC HEAT OF NUCLEUS 104Pd UNDER MICROSCOPIC IBM Shi Zhu-yi (石筑一), Liu Yong (刘庸), Sang Jian-ping (桑建平) Chinese Physics, 2001, 10 (2):  117-120.  DOI: 10.1088/1009-1963/10/2/306 Abstract ( 1416 )   PDF (208KB) ( 600 )   By using the microscopic sdgIBM-Fmax approach, procedure of canonical ensemble average and saddle point approximation, thermodynamics of nucleus is established under microscopic IBM. Calculations of spectrum, level density and finite-temperature specific heat for the nucleus 104Pd are carried out. The calculated values are coincident with the experimental data reported recently. The results predict that the shape phase transition in ground state band appears at about T≈0.230MeV and the phase transition of thermal excitation mode takes place at T≈0.630MeV for nucleus 104Pd.

CLASSICAL AREAS OF PHENOMENOLOGY

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STUDY OF THE FOUR-WAVE MIXING DIFFRACTION EFFICIENCY OF LONGITUDINAL-FIELD MULTIPLE-QUANTUM-WELL PHOTOREFRACTIVE DEVICE GROWN AT LOW TEMPERATURE Lu Yuan (陆沅), Li Chun-yong (李春勇), Zhang Yan-feng (张燕峰), Huang Qi (黄绮), Fu Pan-ming (傅盘铭), Zhang Zhi-guo (张治国), Lü Lan-bin (吕兰斌), Chen Hong-zhi (陈宏智), Qu Chang-zhi (曲昌智), Tang Jun-xiong (汤俊雄) Chinese Physics, 2001, 10 (2):  121-123.  DOI: 10.1088/1009-1963/10/2/307 Abstract ( 996 )   PDF (199KB) ( 326 )   We investigate the relationship between the beam intensity and the four-wave mixing diffraction efficiency of longitudinal-field multiple-quantum-well(LMQW) photorefractive device grown at low temperature. The optimum beam intensity is found. We also explain the different mechanisms of the effect of beam intensity on the diffraction efficiency of the LMQW device and the transverse-field MQW device. Some advice on how to improve the diffraction efficiency is given.

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A NOVEL SCHEME FOR XGM WAVELENGTH CONVERSION BASED ON SINGLE-PORT-COUPLED SOA Zhang Xin-liang (张新亮), Huang De-xiu (黄德修), Sun Jun-qiang (孙军强), Liu De-ming (刘德明) Chinese Physics, 2001, 10 (2):  124-127.  DOI: 10.1088/1009-1963/10/2/308 Abstract ( 1453 )   PDF (251KB) ( 745 )   A novel scheme for wavelength conversion based on cross-gain modulation (XGM) in single-port-coupled semiconductor optical amplifier (SOA), in which the input and output share one port, is brought forward. Experimental results and theoretical analysis show that this scheme can be achieved with simple implementation, high output extinction ratio and large input dynamic range. Based on this novel scheme, 2.5 Gbit/s wavelength up conversion with 12.8 nm span has been demonstrated with the output extinction ratio as high as 15 dB.

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FRACTAL VISCOUS FINGERING AND ITS SCALING STRUCTURE IN RANDOM SIERPINSKI CARPET Tian Ju-ping (田巨平), Yao Kai-lun (姚凯伦) Chinese Physics, 2001, 10 (2):  128-133.  DOI: 10.1088/1009-1963/10/2/309 Abstract ( 1027 )   PDF (309KB) ( 922 )   Viscous fingering (VF)in the random Sierpinski carpet is investigated by means of the successive over-relaxation technique and under the assumption that bond radii are of Rayleigh distribution. In the random Sierpinski network, the VF pattern of porous media in the limit $M\to \infty$ ($M$ is the viscosity ratio and equals $\eta_2$/$\eta_1$ where $\eta_1$ and $\eta_2$ are the viscosities of the injected and displaced fluids, respectively) is found to be similar to the diffusion-limited aggregation (DLA) pattern. The interior of the cluster of the displacing fluid is compact on long length scales when $M=1$, and the pores in the interior of the cluster have been completely swept by the displacing fluid. For finite values of $M$, such as $M\geq10$,the pores in the interior of the cluster have been only partly swept by the displacing fluid on short length scales. But for values of $M$ in $1<M \leq5$, the pores in the interior of the cluster have been completely swept by the displacing fluid on short length scales. The symmetry of the growth of VF is broken by randomizing the positions of the holes. The fractal dimension for VF in fractal space is calculated. However,the sweep efficiency of the displacement processes mainly depends upon the length of the network system and also on the viscosity ratio $M$. The fractal dimension $D$ can be reasonably regarded as a useful parameter to evaluate the sweep efficiencies. The topology and geometry of the porous media have a strong effect on the structure of VF and the displacement process. The distribution of velocities normal to the interface has been studied by means of multifractal theory.Results show that the distribution is consistent with the hypothesis that, for a system of size $L$, $L^{f(\alpha)}$ sites have velocities scaling as $L^{-\alpha}$; and the scaling function $f(\alpha)$ is measured and its variation with $M$ is found.

PHYSICS OF GASES, PLASMAS, AND ELECTRIC DISCHARGES

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STUDY OF THE CORRELATION BETWEEN POWER DEPOSITION OF THE LOWER HYBRID WAVES AND THE HARD X-RAY RADIATION ON HT-7 TOKAMAK Shi Yue-jiang (石跃江), Wan Bao-nian (万宝年), Ling Bi-li (凌必利), Ding Bo-jiang (丁伯江) Chinese Physics, 2001, 10 (2):  134-138.  DOI: 10.1088/1009-1963/10/2/310 Abstract ( 1016 )   PDF (317KB) ( 534 )   A seven-channel NaI(Tl) detector array installed on an HT-7 superconducting tokamak has been used to detect the hard X-ray ($E_{h\nu}>20$keV) emitted from the plasma. The physical mechanism of the lower hybrid waves propagating and absorbed in the plasma is investigated by the measurement of hard X-ray radial profile at different discharge parameters.

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EXPERIMENTAL EVIDENCE OF THE SELF-SIMILARITY AND LONG-RANGE CORRELATIONS OF THE EDGE FLUCTUATIONS IN HT-6M TOKAMAK Wang Wen-hao (王文浩), Yu Chang-xuan (俞昌旋), Wen Yi-zhi (闻一之), Xu Yu-hong (许宇鸿), Ling Bi-li (凌必利), Gong Xian-zu (龚先祖), Liu Bao-hua (刘保华), Wan Bao-nian (万宝年) Chinese Physics, 2001, 10 (2):  139-144.  DOI: 10.1088/1009-1963/10/2/311 Abstract ( 1161 )   PDF (280KB) ( 523 )   To better understand long-time-scale transport dynamics, the rescaled range analysis techniques, the autocorrelation function (ACF) and the probability distribution function (PDF) are used to investigate long-range dependences in edge plasma fluctuations in HT-6M tokamak. The results reveal the self-similar characters of the electrostatic fluctuations with self-similarity parameters (Hurst exponent) ranging from 0.64 to 0.79, taking into consideration the  $\vec{E}_{\text{r}}\times\vec{B}$ rotation-sheared effect. Fluctuation ACFs of both the ion saturation current and the floating potential, as well as PDF of the turbulence-induced particle flux, have two distinct time scales. One corresponds to the decorrelation time scale of local fluctuations (μs) and the other lasts to the order of the confinement time (ms). All these experimental results suggest that some of the mechanisms of the underlying turbulence are consistent with plasma transport as characterized by self-organized criticality(SOC).

CONDENSED MATTER: STRUCTURAL, MECHANICAL, AND THERMAL PROPERTIES

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POSITRON ANNIHILATION STUDY ON SURFACE STRUCTURE OF BIOLOGICAL SAMPLES IMPLANTED BY IONS WITH LOW ENERGY Lu Ting (陆挺), Yu Wei-zhong (郁伟中), Zhou Hong-yu (周宏余), Zhu Guang-hua (朱光华), Wang Xin-fu (汪新福), Wang Chao (王超) Chinese Physics, 2001, 10 (2):  145-147.  DOI: 10.1088/1009-1963/10/2/312 Abstract ( 1193 )   PDF (181KB) ( 729 )   The organic materials of biological samples, such as lima bean and peanut, were implanted respectively by nitrogen ions with an energy of 100 keV and vanadium ions with an energy of 200 keV. The positron annihilation lifetime spectra of implanted and non-implanted samples were compared with each other especially in $\tau_3$ and I3. The experimental results showed that before implantation there were many small holes with diameters of 0.48 and 0.7 nm respectively in lima bean and peanut. After ion implantation, the size of holes would be changed because of organism cross linking and scission. The effective penetration range of implantation of ions with low energy into biological samples is about 200μm.

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EFFECT OF ZnFe22O4 DOPING ON THE OPTICAL PROPERTIES OF TiO2 THIN FILMS Li Guang-hai (李广海), Wu Yu-cheng (吴玉程), Zhang Li-de (张立德) Chinese Physics, 2001, 10 (2):  148-151.  DOI: 10.1088/1009-1963/10/2/313 Abstract ( 1170 )   PDF (183KB) ( 1161 )   Amorphous TiO2 thin films and ZnFe2O4 doped TiO2 composite films were deposited by radio frequency magnetron sputtering. The effect of ZnFe2O4 doping on the optical properties of TiO2 thin films was reported. Our results show that the absorption edge of TiO2 thin films and composite films exhibits a blue shift with decreasing annealing temperature. The absorption edge of composite films has moved to visible spectrum range, and a very large red shift occurs in comparison with TiO2 thin film. An enhanced photoluminescence in ZnFe2O4 doped anatase TiO2 thin film at room temperature was observed.