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991.
Frequency-sensitive stochastic resonance in periodically forced and globally coupled systems 总被引:1,自引:0,他引:1
J. Xiao G. Hu H. Liu Y. Zhang 《The European Physical Journal B - Condensed Matter and Complex Systems》1998,5(1):133-138
A model of globally coupled bistable systems consisting of two kinds of sites, subject to periodic driving and spatially uncorrelated
stochastic force, is investigated. The extended system models the competing process of activators and suppressers. Analytical
computations for linear response of the system to the external periodic forcing is carried out. Noise-induced Hopf bifurcation
is revealed, and stochastic resonance, sensitively depending on the frequency of the external forcing, is predicted under
the Hopf bifurcation condition. Numerical simulations agree with the analytical predictions satisfactorily.
Received: 5 September 1997 / Revised: 13 May 1998 /
Accepted: 18 May 1998 相似文献
992.
Jun Zhang Fangwei Wang Panlin Zhang Xiangdong Sun Qiwei Yan 《Journal of magnetism and magnetic materials》1998,190(3):1085
Magnetic and electric properties of layered perovskites Nd2−2xSr1+2xMn2O7 (x=0.3, 0.4 and 0.5) are sensitive to the doping content x. The sample with x=0.5 is antiferromagnetic (AFM) and insulating. On decreasing x, the AFM ordering is suppressed and a canted AFM or weak ferromagnetic (FM) ordering appears, and the resistivity decreases. The sample with x=0.4 still shows insulating behavior, but a metal–insulator transition is observed for x=0.3. By suggesting the presence of a competition between AFM super-exchange interaction and FM double-exchange interaction, the doping dependence of magnetic and electric properties can be understood. 相似文献
993.
994.
WANG Zhaobing LIAO Yanbiao 《Chinese Journal of Lasers》1998,7(6):485-490
1IntroductionInthelastfewyears,curentandvoltagemeasurementsystemsbasedonopticaldeviceshavebeendeveloped.Anumberofquitediferen... 相似文献
995.
S. Abboudy A. Al-Hajri A. A. Al-Shahrani M. S. Al-Assiri L. Abulnasr A. Sweyllam A. W. Brinkman 《Il Nuovo Cimento D》1998,20(12):1881-1890
Summary A series of zinc stannate (Zn2 SnO4) thin films were prepared at four different substrate temperatures; namely, room-temperature (25°C), 50°C, 100°C and 200°C.
Direct-current resistivity measurements were performed on these samples in the temperature range from room temperature (∼290
K) up to about 500 K. A phase transition (of positive temperature coefficient (PTC) of resistance) was observed in the thin
film grown at room temperature at about 385 K. Other investigated samples showed a semiconducting behaviour of three distinct
conduction mechanisms extending from intrinsic to thermal freeze-out conduction. The width of the band gapE
g
was found to depend on the substrate temperature and was discussed in terms of a formation of a band tailing. Thermal freeze-out
was dominant at the lower temperature region.
On leave from Department of Physics, Faculty of Science, Alexandria University, Alexandria, Egypt. 相似文献
996.
On phase-coherence in rescattering in multiphoton ionization and in higher-order harmonic generation
Summary The recently discovered plateau and rings in high-order multiphoton ionization apparently have their origin in rescattering.
Similarly, rescattering is involved in higher-order harmonic generation. Using a simple one-dimensional model, it is shown
that the phase-coherence in this rescattering process is of considerable importance.
The authors of this paper have agreed to not receive the proofs for correction.
This work has been supported by the East-West Program of the Austrian Academy of Sciences and by the Austrian Ministry of
Science and Transportation under project no. 45.372/2-IV/6/97. One of us (JZK) acknowledges the support of the Polish Committee
of Scientific Research (grant KBN 2 P03B 007 13). 相似文献
997.
首次合成了Ce^3+和Eu^2+共激活氯硅酸镁钙Ca8Mg(SiO4)4Cl2:Ce^3+,Eu^2+高效绿色荧光粉,报道了它们的漫反射光谱、激发和发射光,观察到氯硅酸镁钙中Ce^3+ Eu^2+ 相似文献
998.
999.
1000.
B.C. Gou 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1999,5(1):39-45
Seven low-lying triply exited states of lithium-like oxygen and neon are calculated with the multichannel saddle-point and
saddle-point complex-rotation methods. The term energies are given for these excited states, along with level shifts and partial
Auger widths from dominant decay channels. The mass polarization effect and relativistic corrections are included. The radiative
transition rates are also calculated. These results are compared with other theoretical data in the literature.
Received: 25 May 1998 / Revised: 28 July 1998 / Accepted: 25 August 1998 相似文献