Chin. Phys. B

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HIGHER DIMENSIONAL PAINLEVé INTEGRABLE MODELS FROM THE REAL NONLINEAR EVOLUTION EQUATIONS

Ruan Hang-yu, Chen Yi-xin

Chin. Phys., 2001, 10 (2): 87-96 doi: 10.1088/1009-1963/10/2/001
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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, Wan Ji-hong, Xiao Xian-ci

Chin. Phys., 2001, 10 (2): 97-102 doi: 10.1088/1009-1963/10/2/002
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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.

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LEVEL DENSITY AND FINITE-TEMPERATURE SPECIFIC HEAT OF NUCLEUS ¹⁰⁴Pd UNDER MICROSCOPIC IBM

Shi Zhu-yi, Liu Yong, Sang Jian-ping

Chin. Phys., 2001, 10 (2): 117-120 doi: 10.1088/1009-1963/10/2/006
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By using the microscopic sdgIBM-F_max 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.

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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, Li Chun-yong, Zhang Yan-feng, Huang Qi, Fu Pan-ming, Zhang Zhi-guo, Lü Lan-bin, Chen Hong-zhi, Qu Chang-zhi, Tang Jun-xiong

Chin. Phys., 2001, 10 (2): 121-123 doi: 10.1088/1009-1963/10/2/007
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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, Huang De-xiu, Sun Jun-qiang, Liu De-ming

Chin. Phys., 2001, 10 (2): 124-127 doi: 10.1088/1009-1963/10/2/008
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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, Yao Kai-lun

Chin. Phys., 2001, 10 (2): 128-133 doi: 10.1088/1009-1963/10/2/009
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Viscous fingering (VF) in random Sierpinski carpet is investigated by means of 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→∞ (M is the viscosity ratio and equals to η₂/η₁ where η₁ and η₂ 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≥10, 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 1f(α) sites have velocites scaling as L^-α; and the scaling function f(α) is measured and its variation with M is found.

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SUPERSYMMETRIC SU(1|2) GAUDIN MODEL

Cao Jun-peng, Hou Bo-yu, Yue Rui-hong

Chin. Phys., 2001, 10 (2): 103-108 doi: 10.1088/1009-1963/10/2/003
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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 U_q[osp(1|2)] SYMMETRY

Yang Wen-li

Chin. Phys., 2001, 10 (2): 109-112 doi: 10.1088/1009-1963/10/2/004
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Using the algebraic Bethe ansatz method, we obtain the eigenvalues of the transfer matrix of the supersymmetric model with U_q[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, Yue Rui-hong, Shi Kang-jie, Hou Bo-yu

Chin. Phys., 2001, 10 (2): 113-116 doi: 10.1088/1009-1963/10/2/005
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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.

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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, Wan Bao-nian, Ling Bi-li, Ding Bo-jiang

Chin. Phys., 2001, 10 (2): 134-138 doi: 10.1088/1009-1963/10/2/010
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A seven-channel NaI(Tl) detector array installed on an HT-7 superconducting tokamak has been used to detect the hard X-ray (E_hν>20keV) 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, Yu Chang-xuan, Wen Yi-zhi, Xu Yu-hong, Ling Bi-li, Gong Xian-zu, Liu Bao-hua, Wan Bao-nian

Chin. Phys., 2001, 10 (2): 139-144 doi: 10.1088/1009-1963/10/2/011
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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}_r×{\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).

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POSITRON ANNIHILATION STUDY ON SURFACE STRUCTURE OF BIOLOGICAL SAMPLES IMPLANTED BY IONS WITH LOW ENERGY

Lu Ting, Yu Wei-zhong, Zhou Hong-yu, Zhu Guang-hua, Wang Xin-fu, Wang Chao

Chin. Phys., 2001, 10 (2): 145-147 doi: 10.1088/1009-1963/10/2/012
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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 τ₃ 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, Wu Yu-cheng, Zhang Li-de

Chin. Phys., 2001, 10 (2): 148-151 doi: 10.1088/1009-1963/10/2/013
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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.