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1994年, 第3卷, 第9期　刊出日期：1994-09-20 上一期    下一期

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A NEW DIRECT METHOD FOR HEAT KERNEL EXPANSION IN CURVED SPACE AND THE RESUMMED FORM OF NONDERIVATIVE TERM 许殿彦 1994 (9):  641-652.  doi: 10.1088/1004-423X/3/9/001 摘要 ( 1199 )   PDF(217KB) ( 361 )   A new method is proposed for heat kernel expansion in curved space, without using the recursion relation. The existence of the resummed form of nonderivative terms arising out of X from the operator A =-□+ X is proved. The De Witt-Seeley-Gilkey coefficients E2(x) and E4(x) are derived. 相关文章 | 计量指标

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THE UNIVERSAL TRANSITION OF PLATEAU STRUCTURE OF LYAPUNOV EXPONENTS 汪秉宏, 陈国义, 顾国庆 1994 (9):  653-666.  doi: 10.1088/1004-423X/3/9/002 摘要 ( 1218 )   PDF(285KB) ( 467 )   The universal transition of Lyapunov exponents between conservative limit and dissipa-tire limit of nonlinear dynamical system is studied. It is discovered numerically and proved analytically that for homogeneous dissipative two-dimensional maps, along the equal dissi-pation line in parameter space, the Lyapunov exponents of attractor orbits possess a plateau structure and strict symmetry about its plateau value, The ratios between the plateau width and the stable window width of period 1-4 orbits for Henon map are calculated. The result shows that the plateau structure of Lyapunov exponents remains invariant for the attractor orbits belonging to a period doubling bifurcation sequence. This fact reveals a new universal transition behavior between order and chaos when the dissipation of the dynamical system is weakened to zero. 相关文章 | 计量指标

GENERAL

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INHOMOGENEOUS FLUCTUATION DISTRIBUTION IN THE OUTPUT OF STOCHASTIC RESONANCE SYSTEMS AND ITS APPLICATION 温孝东, 胡岗, 杨春元, 李蓉, 龚德纯, 王辅忠 1994 (9):  667-675.  doi: 10.1088/1004-423X/3/9/003 摘要 ( 1375 )   PDF(235KB) ( 648 )   Inputting a periodic signal mixed with white noise into a bistable system, we find that the fluctuation distribution in the time series of the output is strongly inhomogeneous. In certain phase part fluctuation is very low under the stochastic resonance condition, and consequently, the signal-to-noise ratio (SNR) there is much higher than that of the input. This mechanism can be used to design a nonlinear receiver to extract the signed from noise with SNR three times higher than the largest SNR obtained so far by the optimal linear filter. 相关文章 | 计量指标

CLASSICAL AREAS OF PHENOMENOLOGY

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LIGHT-INDUCED ABSORPTION ENHANCEMENT IN C60 TOLUENE SOLUTION 赵江, 张占祥, 叶佩弦, 解思深, 张泽勃, 郑幼风 1994 (9):  676-681.  doi: 10.1088/1004-423X/3/9/004 摘要 ( 1252 )   PDF(171KB) ( 340 )   Absorption enhancement induced by a pump beam of 532 nm in C60 toluene solution has been observed and studied from 560nm to 63Onm, and the absorption cross section of its lowest triplet state has been determined in this wavelength range according to our theoretical model. 相关文章 | 计量指标

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INVESTIGATION ON THE COMPOSITION AND STRUCTURE OF SILICON NITRIDE FILM PREPARED BY ECR-PECVD 陈俊芳, 程绍玉, 任兆杏, 张束清, 宁兆元, 吴雪梅 1994 (9):  682-689.  doi: 10.1088/1004-423X/3/9/005 摘要 ( 1289 )   PDF(238KB) ( 438 )   In this paper, the effect of temperature on the composition and structure of the Si3N4 thin film is investigated. X-ray diffraction pattern and transmission electron microscope (TEM) analyses show that the Si3N4 film undergoes the transition from amorphous to crystalline phase with increasing deposition temperature. Infra-red qualitative analysis shows that the content of hydrogen decreases with increasing deposition temperature.The stoichiometric of Si3N4 is investigated by X-ray photoelectron spectroscopy or electron spectroscopy for chemical analysis. 相关文章 | 计量指标

CONDENSED MATTER: STRUCTURAL, MECHANICAL, AND THERMAL PROPERTIES

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MONTE CARLO SIMULATION OF THE ION BEAM ENHANCED DEPOSITION OF SILICON NITRIDE FILMS 邵其鋆, 潘正瑛 1994 (9):  690-696.  doi: 10.1088/1004-423X/3/9/006 摘要 ( 1163 )   PDF(186KB) ( 413 )   In this paper, the growth process of silicon nitride films by ion beam enhanced depo-sition (IBED) is investigated by using the dynamic Monte Carlo simulation, which is based on the binary collision approximation. The effects of the incident angles, energies of the bombarded ions and the interaction potentials on the composition of the films are discussed. The successive and alternate deposition process of silicon and implantation of nitrogen ions have been applied to simulate the actual continuous and synchronous process of IBED. The relationship between the calculated composition of the films and the ion/atom arrival ratio of implanted nitrogen ions to deposited silicon atoms has been established. The composition profile obtained by computer simulation is in good agreement with the experimental results. 相关文章 | 计量指标

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THERMALLY ACTIVATED HOPPING IN Dy1-xPrxBa2Cu3O7-δ SYSTEM 曹效文 1994 (9):  697-701.  doi: 10.1088/1004-423X/3/9/007 摘要 ( 1267 )   PDF(152KB) ( 344 )   The temperature dependence of resistivity in Dy1-xPrxBa2Cu3O7-δ system with x>0.6 was measured. The experimental results show that Pr substitution leads to the localization of mobile holes and such a localization is enhanced with increasing Pr concentration. The gradually enhancing of localization induces Anderson transitions one by one in this system, including the transition from the conduction by excitation of holes to the one by thermal activation hopping between localized states, the so called Anderson transition type-I, and the transition from nearest neighbor hopping (NNH) to variable range hopping (VRH), the Anderson transition type-II, and the Anderson transition type-lI from 3D to 2D. 相关文章 | 计量指标

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THE CRYSTALLIZATION OF Bi IN THE ANNEALED a-Ge/Bi BILAYER AND ITS EFFECT ON CONDUCTIVITY 李玉芝, 李铁, 许存义, 周贵恩, 张裕恒 1994 (9):  702-707.  doi: 10.1088/1004-423X/3/9/008 摘要 ( 1213 )   PDF(140KB) ( 380 )   In this paper, the crystallization behaviors and transport properties are investigated for a-Ge/Bi bilayers annealed at different temperatures. For 200nm/100nm bilayers, it is found that the orientations of Bi in the bilayers annealed at 200℃ and 340℃ are preferred, as well as the original one. But they are random when the bilayers are annealed at tem-peratures between 240℃ and 300℃. For 200nm/50nm bilayers, the orientation of Bi are always preferred. Corresponding to the orientations mentioned above, the minimum on the R(300K)-Ta curve appears only in the case of 200nm/100 nm bilayers. 相关文章 | 计量指标

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LOW-FIELD MICROWAVE SIGNAL IN UNDOPED AND Sb-DOPED Bi-Pb-Sr-Ca-Cu-O 侯碧辉, 王梅生, 陈兆甲, 许勤论, 金通政 1994 (9):  708-711.  doi: 10.1088/1004-423X/3/9/009 摘要 ( 1076 )   PDF(129KB) ( 409 )   Non-resonant low-field microwave signal in undoped Bi-Pb-Sr-Ca-Cu-O (2223) sample inches monotonously with decreasing temperature, like that in many bulk samples of high-Tc superconductor. But the signed of a Sb-doped sample shows a peak at 103K, and declines gradually and tends to stabilize when the temperature is further reduced. A distorted 2223 phase (i.e., 130K phase) which was an intergrowth of 2223 and insulating monoclinic phases in the Sb-doped sample, was unstable, and it might change into the stable insulating monoclinic phase and lost its superconductivity at lower temperatures. 相关文章 | 计量指标