摘要：
The stability of the sonic point in isothermal disc accretion is examined for the case in which the viscous stress has a diffusive form, rather than the form of the conventional Shakura-Sunyaev-type alpha-model. The results show that the sonic point is always a saddle and always stable against small-amplitude perturbations, in contrast to the case of the alpha-model. The results suggest that the topological type of the sonic point and the stability of the point against small-amplitude perturbations are related for a wide range of problems: a saddle-type sonic point is stable, while a nodal one is unstable.
摘要：
In this paper, we have investigated the influence of the counter-rotating terms on the squeezing of light in the two-photon Jaynes-Cummings model by means of the nonrelativistic QED. We verified that the effect of the virtual-photon field increases the squeezing. The relations between the degree of squeezing and the frequency of field, the mean photon number, and the atom-field coupling constant have also been analyzed.
作者机构：
[XU, C] Institute of Particle Physics, Huazhong Normal University, Wuhan 430070, China
通讯机构：
[XU, C] H;HUAZHONG NORMAL UNIV, INST PARTICLE PHYS, WUHAN 430070, PEOPLES R CHINA.
摘要：
In this paper we will describe a new nuclear emulsion technique, a digital controlled method, for making fast and accurate measurement and three-dimensional reconstruction of charged particle tracks in a special nuclear emulsion chamber, which is used as detector with target foil of silver, gold or lead nuclei by the CERN/EMU01 experiment and has the best resolution in the investigation of very high multiplicity in ultra-relativistic heavy ion collisions.
作者机构：
CHINESE CTR ADV SCI & TECHNOL,WORLD LAB,BEIJING 100080,PEOPLES R CHINA.;HUAZHONG NORMAL UNIV,DEPT PHYS,WUHAN 430070,PEOPLES R CHINA.;UNIV SCI & TECHNOL CHINA,DEPT PHYS,HEFEI 230026,PEOPLES R CHINA.;[YANG, JL] UNIV SCI & TECHNOL CHINA,CTR FUNDAMENTAL PHYS,HEFEI 230026,PEOPLES R CHINA.
通讯机构：
[YANG, JL] U;UNIV SCI & TECHNOL CHINA,CTR FUNDAMENTAL PHYS,HEFEI 230026,PEOPLES R CHINA.
摘要：
The stability, electronic and magnetic properties, and reactivity of icosahedral M Co12 clusters are studied using the discrete variational local-spin-density-functional method, where M=Ti, V, Cr, Mn, Fe, Co, and Ni. By means of the binding-energy calculation, we obtained the M-Co bond length of the clusters and compared their relative stability. We calculated the electronic structure of the clusters in their equilibrium configurations. The calculated results show that all the clusters have metallic character, and that the clusters with M being Ti, Mn, or Co have closed electronic shells while the others have open electronic shells and are expected to distort further. The results also indicate that the cluster moment is reduced by the substitution of the central Co atom with an M atom, and that the average moment per atom of all clusters is larger than that of the bulk Co. Based on the results of electronic structures, we further analyzed the reactivity of the clusters toward H2, N2, and CO molecules and found a strong dependence on the central M atom. Our results compare well with the available experimental results.
作者机构：
[PENG, JS; LI, GX] HUAZHONG NORMAL UNIV,DEPT PHYS,WUHAN 430070,PEOPLES R CHINA.;[PENG, JS] HARVARD SMITHSONIAN CTR ASTROPHYS,INST THEORET ATOM & MOLEC PHYS,CAMBRIDGE,MA 02138, USA.
通讯机构：
[PENG, JS] H;HARVARD SMITHSONIAN CTR ASTROPHYS,INST THEORET ATOM & MOLEC PHYS,CAMBRIDGE,MA 02138, USA.
摘要：
We investigate the effect of the dipole-dipole interaction on the dynamic properties and the atomic coherent trapping of a two-identical-atom system in the presence of a laser field by means of quantum-electrodynamics theory. The influence of the dipole-dipole interaction on the collapses and revivals of the atomic population is revealed. The conditions of the atomic coherent trapping are given. A way to measure optically the coupling strength between the atoms is pointed out. We also show that the effect of the dipole-dipole interaction may be screened due to the coherent field in certain atomic superposition states.
作者机构：
ACAD SINICA, INST HIGH ENERGY PHYS, BEIJING 100039, PEOPLES R CHINA.;CCAST, WORLD LAB, BEIJING 100080, PEOPLES R CHINA.;HUA ZHONG NORMAL UNIV, INST PARTICLE PHYS, WUHAN 430070, PEOPLES R CHINA.;[ZHUANG, PF] CCAST (World Laboratory), PO Box 8730, Beijing 100080, China<&wdkj&>Institute of Particle Physics, Hua-Zhong Normal University, Wuhan 430070, China;[CHAO, WQ] CCAST (World Laboratory), PO Box 8730, Beijing 100080, China<&wdkj&>Institute of High Energy Physics, Academia Sinica, Beijing 100039, China
通讯机构：
[Chao Weiqin] C;CCAST (World Laboratory), PO Box 8730, Beijing 100080, China<&wdkj&>Institute of High Energy Physics, Academia Sinica, Beijing 100039, China
摘要：
The relation between the formation time and the intranuclear cascading in high-energy hA collisions is discussed. By comparing the final-state rapidity distribution obtained from a simple model with the experimental data, the appropriate formation time is estimated as about 1 fm.
作者机构：
[WU, YF; LIU, LS] Institute of Particle Physics, Hua-Zhong Normal Univeristy, Wuhan 430 070, People’s Republic of China
通讯机构：
[WU, YF] H;HUA ZHONG NORMAL UNIV,INST PARTICLE PHYS,WUHAN 430070,PEOPLES R CHINA.
摘要：
It is argued that, accounting for the anisotropy of phase space, the local fluctuations of multiplicity in high energy multiparticle production are self-affine rather than self-similar. Evidence is given confirming self-affinity in phase-space distributions. A method is proposed to extract the characteristic parameter of self-affinity, the Hurst exponent, from the experimental data iteratively.
期刊：
JOURNAL OF PHYSICS-CONDENSED MATTER,1993年5(36):6653-6662 ISSN：0953-8984
通讯作者：
YANG, JL
作者机构：
CHINA CTR ADV SCI & TECHNOL,WORLD LAB,BEIJING 100080,PEOPLES R CHINA.;ACAD SINICA,INT CTR MAT PHYS,SHENYANG 110015,PEOPLES R CHINA.;HUAZHONG NORMAL UNIV,DEPT PHYS,HUBEI 430070,PEOPLES R CHINA.;UNIV SCI & TECHNOL CHINA,DEPT PHYS,HEFEI 230026,PEOPLES R CHINA.;[YANG, JL] UNIV SCI & TECHNOL CHINA,CTR FUNDAMENTAL PHYS,HEFEI 230026,PEOPLES R CHINA.
通讯机构：
[YANG, JL] U;UNIV SCI & TECHNOL CHINA,CTR FUNDAMENTAL PHYS,HEFEI 230026,PEOPLES R CHINA.
摘要：
A general method is suggested to determine the site preference of alloying additions in intermetallic compounds with either stoichiometric or non-stoichiometric compositions, by first-principles binding-energy calculations using cluster models. The relationships of the site preference of alloying additions, with the compositions of the host elements and with the concentrations of the additions themselves in the host are established. The validity and reliability fo the method are tested by applying it to the site preference study of some ternary additions (Sc, Ti, V, Fe, Co, Cu, Nb, Mo and Pd) in gamma '-Ni3Al. The results obtained are in complete agreement with the experimental data, which proves that the method is successful.
作者机构：
HUAZHONG NORMAL UNIV, DEPT PHYS, WUHAN 430070, PEOPLES R CHINA.;UNIV SCI & TECHNOL CHINA, DEPT PHYS, HEFEI 230026, PEOPLES R CHINA.;UNIV SCI & TECHNOL CHINA, CTR FUNDAMENTAL PHYS, HEFEI 230026, PEOPLES R CHINA.;[YANG, JL] CHINESE CTR ADV SCI & TECHNOL, WORLD LAB, POB 8730, BEIJING 100080, PEOPLES R CHINA.
通讯机构：
[YANG, JL] C;CHINESE CTR ADV SCI & TECHNOL, WORLD LAB, POB 8730, BEIJING 100080, PEOPLES R CHINA.
摘要：
The site preference of ternary additions Mg, V, Cr, Mn, Ga, and Mo in γ-TiAl intermetallic compounds is studied using the discrete-variational local-density-functional method with cluster models. The relations of the site preference of ternary additions with the compositions of the host elements and with the concentrations of the additions themselves in the host are obtained. The results explain satisfactorily the experimental observations and are discussed with the effects of ternary additions in improving the ductility of γ-TiAl.
期刊：
EUROPEAN PHYSICAL JOURNAL C,1992年53(2):273-275 ISSN：1434-6044
通讯作者：
WU, YF
作者机构：
[WU, YF; LIU, LS] Institute of Particle Physics, Hua-Zhong Normal University, Wuhan, People's Republic of China
通讯机构：
[WU, YF] H;HUA ZHONG NORMAL UNIV,INST PARTICLE PHYS,WUHAN 490070,PEOPLES R CHINA.
关键词：
Field Theory;Opposite Direction;Elementary Particle;Quantum Field Theory;Transverse Momentum
摘要：
The dependences of intermittency degree on moment-order, multiplicity and transverse momentum are discussed. The different dependences of intermittency degree on moment order at different energies are utilized to show that the dependences of intermittency degree on multiplicity are in opposite directions in low and high energy regimes. It is argued that these different trends imply that intermittency degree depends on other more basic quantity, such as transverse momentum.
摘要：
By calculating the effective potential of the nontopological soliton model at finite temperature and density, the temperature and the chemical potential dependence of the bag constant is obtained. The feature of deconfinement phase transition is analyzed. It turns out that, in this model, the deconfinement phase transition is of first order; the analysis of the phase transition feature suggests the coexistence of a deconfinement phase and a confinement phase.
通讯机构：
[CHEN, LH] C;CENT CHINA NORMAL UNIV,DEPT PHYS,WUHAN 430070,PEOPLES R CHINA.
关键词：
联合概率分布;噪声;方程
摘要：
We obtain the equation for the steady state joint probability distribution of the system driven by external and internal noises simultaneously, where external noise is the dichotomous noise and internal noise is the Gaussian white noise. As to the application of our equation, we discuss two examples for which the correlation functions and associated relaxation times are calculated. We find the coupling effect of the external and the internal noises for the relaxation time.
摘要：
The influence of the atomic coherence on the collapses and revivals of the atomic inversion is some generalized Jaynes-Cummings models is examined. It is shown that the collapse and revival times are independent of the initial state of the atom, while the amplitude of the revivals is sensitive to this coherence and the phase of the field. Under certain conditions, the amplitude of the revivals can be decreased and the revivals can become the doublet structure.
作者机构：
[SHEN, K; QIU, ZP] Institute of Particle Physics, Hua-Zhong Normal University, Wuhan 430070, China
通讯机构：
[SHEN, K] H;HUA ZHONG NORMAL UNIV,INST PARTICLE PHYS,WUHAN 430070,PEOPLES R CHINA.
摘要：
Based on chiral Ward-Takahashi identities with composite fields, we develop a method to investigate fermion mass generation and bound-state spectra in the (2+1)-dimensional chiral Gross-Neveu model.
摘要：
In this paper, we have investigated the time evolution of the phase operator of the radiation field in the Jaynes-Cummings model with and without the rotating-wave approximation, making use of the phase formalism of Barnett and Pegg [J. Mod. Opt. 36, 7 (1989); Phys. Rev. A 39, 1665 (1989)]. We verify by an analytical method that the atomic Rabi oscillation leads to phase dissipation of the radiation field, and also that the effect of the virtual-photon field can exhibit quantum fluctuations in the atom-field-coupling system and lead to a frequency shift of the radiation field.
摘要：
We have studied the time evolution of the phase operators of the radiation field in the system containing a ssV-type three-level atom interacting with the bimodal field by means of the phase formalism given by Pegg and Barnett [J. Mod. Opt. 36, 7 (1989); Phys. Rev. A 39, 1665 (1989)]. That the atomic coherent trapping will happen in an appropriate initial state of the system has also been verified.
