Table of contents

15 August 2001, Volume 10 Issue 8 Previous issue    Next issue

GENERAL

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MASSIVE SCALAR PARTICLE IN THE GRAVITATIONAL FIELD OF A MICROCOSMIC BLACK HOLE Wang Yong-jiu (王永久), Tang Zhi-ming (唐智明) Chinese Physics, 2001, 10 (8):  679-682.  DOI: 10.1088/1009-1963/10/8/301 Abstract ( 1531 )   PDF (210KB) ( 495 )   The finite motion of a massive scalar particle in the gravitational field of a microcosmic black hole with weak relativistic approximation is discussed. In the Schwarzschild field, using the condition for balance $\sigma=0$, we obtain the relation between the produced and captured amplitudes for particles. In the Kerr field we show that the attenuation depends on the moment of the black hole and the attenuation process becomes an exciting one when $\omega< md_h$.

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SIMILARITY REDUCTIONS OF THE (2+1)-DIMENSIONAL BURGERS SYSTEM Liu Dang-bo (刘当波), Chu Kai-qin (储开芹) Chinese Physics, 2001, 10 (8):  683-688.  DOI: 10.1088/1009-1963/10/8/302 Abstract ( 1156 )   PDF (228KB) ( 440 )   In this paper, using the direct method of the (2+1)-dimensional multi-component Burgers system, some types of similarity reductions are obtained. The corresponding group explanations of the reductions, Virasoro integrability and soliton solutions of Burgers system are also discussed.

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MOVING NONLINEAR LOCALIZED MODES FOR ONE-DIMENSIONAL KLEIN－GORDON DIATOMIC LATTICE Zhou Guang-hui (周光辉), Pan Liu-xian (潘留仙), Yan Jia-ren (颜家壬) Chinese Physics, 2001, 10 (8):  689-693.  DOI: 10.1088/1009-1963/10/8/303 Abstract ( 1020 )   PDF (221KB) ( 717 )   We study analytically the moving nonlinear localized vibrational modes (discrete breathers) for a one-dimensional Klein－Gordon diatomic lattice in the whole $\omega(q)$ plane of the system by means of a semi- discrete approximation, in which the carrier wave of the modes is treated explicitly while the envelope is described in the continuum approximation. We find that both pulse and kink envelope moving modes for this lattice system can occur with certain carrier wave vectors and vibrational frequencies in separate regions of the $\omega(q)$ plane. However, the kink envelope moving modes have not been reported previously for this lattice system.

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NEW EXPLICIT AND EXACT TRAVELLING WAVE SOLUTIONS FOR A COMPOUND KdV－BURGERS EQUATION Xia Tie-cheng (夏铁成), Zhang Hong-qing (张鸿庆), Yan Zhen-ya (闫振亚) Chinese Physics, 2001, 10 (8):  694-697.  DOI: 10.1088/1009-1963/10/8/304 Abstract ( 1147 )   PDF (196KB) ( 701 )   In this paper, new explicit and exact travelling wave solutions for a compound KdV－Burgers equation are obtained by using the hyperbola function method and the Wu elimination method, which include new solitary wave solutions and periodic solutions. Particularly important cases of the equation, such as the compound KdV, mKdV－Burgers and mKdV equations can be solved by this method. The method can also solve other nonlinear partial differential equations.

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STATISTICAL ENTROPIES OF THE TAUB－NUT/BOLT AdS SPACES FROM THE HORIZON CONFORMAL FIELD THEORY Jing Ji-liang (荆继良), Zhou San-qing (周三庆), Huang Yi-bin (黄亦斌) Chinese Physics, 2001, 10 (8):  698-702.  DOI: 10.1088/1009-1963/10/8/305 Abstract ( 1130 )   PDF (182KB) ( 517 )   The covariant phase technique is used to compute the constraint algebra of the four-dimensional space-times which are asymptotic to anti-de Sitter (AdS), such as the planar Taub－NUT AdS and Taub－bolt AdS spaces, and the hyperbolic Taub－bolt AdS space. The standard Virasoro subalgebrae with corresponding central charges for these objects are constructed and the resulting densities of states yield the expected Bekenstein－Hawking entropies.

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FRUSTRATION EFFECT ON SYNCHRONIZATION AND CHAOS IN COUPLED OSCILLATORS Zheng Zhi-gang (郑志刚) Chinese Physics, 2001, 10 (8):  703-707.  DOI: 10.1088/1009-1963/10/8/306 Abstract ( 1125 )   PDF (207KB) ( 533 )   Synchronization dynamics in an array of coupled periodic oscillators with quenched natural frequencies are discussed in the presence of homogeneous phase shifts (frustrations). Frustration-induced desynchronization and chaos are found. The torus-doubling route to chaos, toroidal chaos and torus crisis are investigated.

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A NEW SLIDING MODE CONTROL FOR A CLASS OF UNCERTAIN TIME-DELAY CHAOTIC SYSTEMS Li Li-xiang (李丽香), Peng Hai-peng (彭海朋), Guan Bao-zhu (管保柱), Xu Jin-ming (徐进明) Chinese Physics, 2001, 10 (8):  708-710.  DOI: 10.1088/1009-1963/10/8/307 Abstract ( 1305 )   PDF (101KB) ( 539 )   We propose a new sliding mode control scheme for a class of uncertain time-delay chaotic systems. It is shown that a linear time invariant system with the desired system dynamics is used as a reference model for the output of a time-delay chaotic system to track. A sliding mode controller is then designed to drive the output of the time-delay chaotic system to track the desired linear system. On the sliding mode, the output of the controlled time-delay chaotic system can behave like the desired linear system. A simulation example is given in support of the proposed control scheme.

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INVERSE SYNCHRONIZATION OF CHAOTIC SYSTEMS IN AN ERBIUM-DOPED FIBRE DUAL-RING LASER USING THE MUTUAL COUPLING METHOD Wang Rong (王荣), Shen Ke (沈柯) Chinese Physics, 2001, 10 (8):  711-715.  DOI: 10.1088/1009-1963/10/8/308 Abstract ( 1144 )   PDF (149KB) ( 996 )   Inverse synchronization of chaos is a type of synchronization in which the dynamical variables of two chaotic systems are inversely equal. In this paper, we present a scheme for inverse synchronization of two chaotic systems in an erbium-doped fibre dual-ring laser using the mutual coupling method. For realistic values of the systems, we demonstrate two kinds of results, as follows. (1) Two independent identical chaotic systems can go into inversely synchronized chaotic oscillation for coupling greater than 0.03. (2) When some parameter of one system varies, the state of the coupled systems could go into some periodic states directly or by inverse bifurcation. Simultaneously, they will lose the synchronization as the parameter changes.

ATOMIC AND MOLECULAR PHYSICS

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PRECISE MEASUREMENT OF DENSITY-DEPENDENT SHIFT BY WAVELENGTH MODULATION REFLECTION SPECTROSCOPY Xiao Lian-tuan (肖连团), Zhao Jian-ming (赵建明), Li Chang-yong (李昌勇), Jia Suo-tang (贾锁堂), Zhou Guo-sheng (周国生) Chinese Physics, 2001, 10 (8):  716-719.  DOI: 10.1088/1009-1963/10/8/309 Abstract ( 1226 )   PDF (119KB) ( 432 )   The density dependence of the line shift of the cesium D2 line is studied with sub-Doppler selective reflection spectroscopy. By use of wavelength modulation and sixth-harmonics detection we observed the coefficient of the pressure-induced shift of the 6S1/2(F=4)→6P3/2(F'=3) hyperfine transition of the cesium D2 line $\Delta \delta/\rho$ = -0.9(5)×10-8cm3. In the limit $\rho=0$ a frequency shift about -3MHz remains, which may be attributed to long-range atom－surface interactions. The experimental results can be used in measurements of the local field-induced frequency shift at high atomic densities with sufficient accuracy.

CLASSICAL AREAS OF PHENOMENOLOGY

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SQUEEZING PROPERTIES OF A TRAPPED ION IN THE STANDING-WAVE LASER Fang Mao-fa (方卯发), Liu Xiang (刘翔) Chinese Physics, 2001, 10 (8):  720-724.  DOI: 10.1088/1009-1963/10/8/310 Abstract ( 1237 )   PDF (141KB) ( 551 )   We investigate the squeezing properties of a trapped ion in a standing-wave laser. Our results show that the squeezing of a trapped ion in the standing-wave laser is dependent on its position in the latter, the detuning parameter and the initial average phonon number.

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PUMP-TUNING KTP OPTICAL PARAMETRIC OSCILLATOR WITH CONTINUOUS OUTPUT WAVELENGTH PUMPED BY A PULSED TUNABLE Ti:SAPPHIRE LASER Ding Xin (丁欣), Yao Jian-quan (姚建铨), Yu Yi-zhong (于意仲), Yu Xuan-yi (禹宣伊), Xu Jing-jun (许京军), Zhang Guang-yin (张光寅) Chinese Physics, 2001, 10 (8):  725-729.  DOI: 10.1088/1009-1963/10/8/311 Abstract ( 1153 )   PDF (138KB) ( 467 )   We report on the implementation of a KTP optical parametric oscillator pumped by a pulsed tunable Ti:sapphire laser. Two major improvements were achieved, including the connection of the signal and idler tuning ranges and the high-output conversion efficiency through the signal and idler tuning ranges. Both in the signal and idler, the continuous output wavelength from 1.261 to 2.532μm was obtained by varying the pump wavelength from 0.7 to 0.98μm. The maximum output pulse energy was 27.2mJ and the maximum conversion efficiency was 35.7% at 1.311μm (signal).

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A SENSITIVE AND STABLE CONFOCAL FABRY－PéROT INTERFEROMETER FOR SURFACE ULTRASONIC VIBRATION DETECTION Ding Hong-sheng (丁红胜), Tong Li-ge (童莉葛), Chen Geng-hua (陈赓华) Chinese Physics, 2001, 10 (8):  730-734.  DOI: 10.1088/1009-1963/10/8/312 Abstract ( 1437 )   PDF (528KB) ( 589 )   A new confocal Fabry－Pérot interferometer (CFPI) has been constructed. By using both of the conjugate rays, the sensitivity of the system was doubled. Moreover, the negative feedback control loop of a single-chip microcomputer (MCS-51) was applied to stabilize the working point at an optimum position. The system has been used in detecting the piezoelectric ultrasonic vibration on the surface of an aluminium sample.

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DYNAMICS OF IONIZATION-ENHANCED SPECTRAL EXPANSION IN WATER INDUCED BY AN INTENSE FEMTOSECOND LASER BEAM Wang Shu-feng (王树峰), Qin Yuan-dong (秦元东), Yang Hong (杨宏), Wang Dan-ling (王丹翎), Zhu Chang-jun (朱长军), Gong Qi-huang (龚旗煌) Chinese Physics, 2001, 10 (8):  735-738.  DOI: 10.1088/1009-1963/10/8/313 Abstract ( 1158 )   PDF (119KB) ( 338 )   The dynamic process of white-continuum generation in water was investigated by the pump－probe technique with a femtosecond intense laser at 805nm. The spectrum width of the probe beam was broadened at the blue side and varied with different delay times. This blueshift was attributed to the ionization-enhanced optical nonlinearity, in which both the multi-photon ionization and avalanche ionization had an effect.

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INVESTIGATION OF PHOTOREFRACTIVE TWO-WAVE COUPLING IN Cr-DOPED STRONTIUM BARIUM NIOBATE CRYSTAL Zhao Jian-lin (赵建林), Wang Bin (王彬), Wu Jian-jun (吴建军), Yang De-xing (杨德兴), S. Kapphan, R. Pankrath Chinese Physics, 2001, 10 (8):  739-742.  DOI: 10.1088/1009-1963/10/8/314 Abstract ( 1176 )   PDF (129KB) ( 494 )   We present here the experimental results of photorefractive two-wave coupling in the congruent strontium barium niobate (SBN:61) crystal doped with 1000ppm Cr. Employing a He－Ne laser (632.8nm), we observed the coupling characteristics under different conditions. The crystal shows excellent photorefractive properties, with a high coupling coefficient nearly 6cm-1 as the beam intensity ratio m is less than 100. The saturated coupling coefficient of SBN:61:Cr shows a maximum at a certain external beam crossing angle 2$\theta$peak, which varies with different m, showing a nearly linear dependence on m. The saturated coupling response time $\tau$ is measured to be less than 0.8 s. The response time decreased with increasing beam crossing angles no matter how large m is. We also observed the behaviour of the probe beam in reversed experimental procedures. We found that the probe beam shows a bistable state in both procedures.

CONDENSED MATTER: STRUCTURAL, MECHANICAL, AND THERMAL PROPERTIES

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PLANE ELASTICITY PROBLEM OF TWO-DIMENSIONAL OCTAGONAL QUASICRYSTALS AND CRACK PROBLEM Zhou Wang-min (周旺民), Fan Tian-you (范天佑) Chinese Physics, 2001, 10 (8):  743-747.  DOI: 10.1088/1009-1963/10/8/315 Abstract ( 1464 )   PDF (108KB) ( 556 )   The plane elasticity theory of two-dimensional octagonal quasicrystals is developed in this paper. The plane elasticity problem of quasicrystals is reduced to a single higher-order partial differential equation by introducing a displacement function. As an example, the exact analytic solution of a Mode I Griffith crack in the material is obtained by using the Fourier transform and dual integral equations theory, then the displacement and stress fields, stress intensity factor and strain energy release rate can be calculated. The physical significance of the results relative to the phason and the difference between the mechanical behaviours of the crack problem in crystals and quasicrystals are figured out. These provide important information for studying the deformation and fracture of the new solid phase.

CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES

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TRANSPORT PROPERTIES OF $\mu$c-Si:H FILMS PREPARED BY VERY HIGH HYDROGEN-DILUTED SILANE PLASMA Shi Jian-jun (石建军), Huang Shao-yun (黄少云), Chen Kun-ji (陈坤基), Huang Xin-fan (黄信凡), Xu Jun (徐骏) Chinese Physics, 2001, 10 (8):  748-750.  DOI: 10.1088/1009-1963/10/8/316 Abstract ( 968 )   PDF (111KB) ( 477 )   Highly hydrogen-diluted silane plasma is used to fabricate microcrystalline silicon films in a plasma-enhanced chemical vapour deposition system. X-ray diffraction and micro-Raman scattering spectroscopy are utilized to characterize their microstructure properties. Dark conductivity and drift mobility are measured by the travelling wave method. With the decreasing gas flow ratio of silane-to-hydrogen from 2% to 0.2%, the crystalline volume fraction and the drift mobility increase at room temperature. Meanwhile, the dark conductivity increases initially and then decreases. The relationship between the microstructures and transport properties is discussed.

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CURRENT-DEPENDENT POSITIVE MAGNETORESISTANCE IN Ga-DOPED La0.5Ca0.5MnO3 Chen Xin (陈新), Wang Zhi-hong (王志宏), Li Run-wei (李润伟), Shen Bao-gen (沈保根), Zhao Hong-wu (赵宏武), Zhan Wen-shan (詹文山), Chen Jin-song (陈金松), Zhang Xi-xiang (张西祥) Chinese Physics, 2001, 10 (8):  751-755.  DOI: 10.1088/1009-1963/10/8/317 Abstract ( 1069 )   PDF (165KB) ( 479 )   The magnetic and transport properties of the Ga-doped charge-ordering state La0.5Ca0.5MnO3 have been studied. A current-dependent large positive magnetoresistance (1080%) at 5 K was observed. These observations are interpreted in terms of the spin-dependent tunnelling process between ferromagnetic clusters embedded in an antiferromagnetic matrix.