A relaxation oscillator can be described by two maps: one circle and one inverse circle. The order of map depends on the function form of the modulation signal . Supercritical behaviors of the oscillator were studied experimentally and numerically. Two scaling laws S( f) ∝ f^-δ and τ ∝ |f – f_c|^-γ were verified. Both the scaling exponents δ and γ₂ increase when the order is getting larger.

A new description of the hexadecapole degree of freedom in the medium and heavy mass region in the framework of the fermion dynamical symmetry model is proposed. In this letter, the k-active case is discussed in detail, in which the pairing and multipole operators generate Sp₁₀ group. The energy spectra are derived for two limiting cases. The results show that these limits and those in the s. d. g ZBM have one to one correspondence when N₁ (=N boson number in the s. d. g IBM)≤ Ω₁/5.

Experiments have been conducted on the circular Couette system, established recently in our laboratory. By using an optical-electronic modulation feedback Laser Doppler Velocimetry technique, the velocity time series data with higher signal-noise ratio, power spectra, phase ort traits and Poincare sections were obtained. Two scenarios to chaos were observed. One is the Ruelle-Takens scenario, while the other (when both cylinders of the Couette system are counter-rotating) is quite different from it. A tremendous variety of flow regimes and a new state were observed. A tentative explanation is made for the new state.

We report here our recent studies of ultrastrong Langmuir tubulence by numerical simulation in two-fluid plasma. Many nonlinear phenomena, such as the formation and collapse of solitons, the onset of wavebreaking, the burnout and reborn of cavitons and so on, are observed in the simulation. Very intense cavitons ( |E|²/2ε₀T_e3 and δ_n/n₀ 0.3 ) caused by relative weak pump ( (|E₀|²/2ε₀T_e 0.05 ) and fluctuations ( δ_n/n₀ 0.003 ) can exist in the system which are beyond the approximation of the Zakhorov model.

The dissociation of CO on oxygen contaminated Ni{00l}c(2x2)-A1 surface at room temperature has been observed by electron energy loss spectroscopy. The CO dissociation rate is proportional to the oxygen contamination on the surface.

We have used ab initio pseudopotential method to generate basis wavefunctions and eigen energies to carry out first principle calculations of the static macroscopic dielectric constant for GaAs and Gap. The resulted converged random phase approximation (RPA) value is 12.55 and 10.71, in excellent agreement to the experimental value of 12.4 and 10.86, respectively. The inclusion of the exchange correlation contribution makes the calculated result slightly worsen. A convergence test with respect to the number of k points in Brillouin zone (BZ) integration was carried out. Sixty irreducible BZ k points were wed to achieve the converged results. Integration with only 10 special k points increased the RPA value by 15%.

A recently developed embedded cluster scheme is applied to study the coverage dependence of charge transfer between Cs and the (001) surface of all 5d transition metals, which agrees with the jellium-slab model calculation given by the first principle band method. The correlation between the initial drop of work function during cesiation caused by this charge transfer and the unfilled d band of the substrates is revealed

It is shown that there exists the anisortropic nature of pressure dependence for the superconducting transition temperature and resistivity in Bi₂Sr₂CaCu₂O_y single crystals. The maximum superconducting critical temperature and the minimum resistance along a-b plane under about 8kbar have been observed, no obvious structure phase transition was observed at room temperature under pressure, and there is not the same behaviour along the c axis up to 13kbar. A slight difference between the rates dT_c/dP along a-b plane and c axis was also found. This anisotropy may have close relation to the coupling between layers.

The influence of Nd:MgO:LiNbO₃ composition on the optical quality and resistance to photorefraction has been studied. Nd:MgO:LiNbO₃ (1mol% Nd₂O₃, 7.5 mol% MgO) crystal has been found to have enhanced resitance to photore-fraction, lower phase matching temperature and good optical quality. This crystal is promising material for self-frequency-doubled and self-Q-switched laser devices.

The sintered samples of Y-Ba-Cu-O were quenched in air at different temperatures from 950 to 300℃ and their room-temperature far-infrared reflectance spectra were obtained. The spectra were studied by using the Drude model and Lorentzian phonon. From the curve of carrier density us quench temperature, an orthorhombic-tetragonal phase change is indicated. The phonon oscillation strength changes were explained by the abnormal sensibility in the reflectance spectra.

Time-resolved fluorescence decays were first performed on hematoporphyrin derivative laser No.3 in buffer at different micelles concentration. The fluorescence lifetime constants, measured with a time-correlated single photon counting system, could be fitted by two or three exponential components with different relative peak amplitudes depending on the observation wavelength, thus indicating the presence of different emitting molecular species and/or of molecular species in different aggregational states.

The dynamic Monte Carlo program including a bombardment-induced Gibbsian segregation process was used to calculate angular distributions of individual elements from sputtered Cu_0.5Pt_0.5 alloy in the Ar ion energy range between 0.2 and 1.5keV. Calculated results show that for each investigated incident energy, the angular distribution of the Pt clement is more forward-pointed than that of the Cu one; the reason may be that different percentage of sputtered atoms (37~45% of Pt and 12~19% of Cu) come from beneath the topmost layer.

We present the novel results of excitation intensity dependent photoluminescence (PL) in a-C:H and a-C thin films. Sublinear and superlinear phenomena of PL have been observed for a-C:H films. There are two PL bands in a-C films under lower excitation intensity. These results are qualitatively explained in the light of band tail state saturation and the contribution of gap states.

In this paper we constructed the formula of the third quantization of a solvable model in quantum cosmology based on the Brans-Dicke theory and got an abnormal distribution.