A general formula for determinating the proportions of different unit-cells in a projection lattice is given. It is found that there exist certain relations between the occurrence frequency of a specified unit-cell in the aperiodic lattice and the projection (in a special subspace E^2') of the corresponding facets of the hyper-unit-cell of the n-dimensional periodic lattice. Based upon these, some special cases are discussed.

The Faddeev-Jackiw quantization procedure is applied to the gauge invariant version of the linear self-dual constrained theory. The equivalence of the gauge invariant and the gauge noninvariant versions is discussed.

The one- and two-particle states in the sinh-Gordon and sine-Gordon models in (1+1) dimensions are investigated by using the gaussian wave-functional approach. We find that (i) the renormalized mass parameter is just the variational one particle mass, and (ii) there are no two-particle bound states in the sinh-Gordon model, but in the sine-Gordon model, there exist two-particle bound states.

The differential cross sections for e^--Ar and e⁺-Ar elastic scattering are calculated by relativistic partial wave expansion method. In the processes an incident particle (electron or positron) is treated as moving relativistically in an effective central potential. For electron-atom scattering, the effective potential is calculated by relativistic self-consistent-field (SCF) method with the Slater local exchange approximation. For the positron scattering, the effective potential is the electrostatic potential determined by the ground-state electron charge density calculated by the SCF method. For atomic target polarization due to the incident charge particle(e1ectron or pwitron), the effect is treated approximately by adding a static polarization potential to the SCF potentials. The calculated results show that the polarization effect is very important for the low energy positron-atom scattering.

A pinhole structure has been adopted to serve as the exit window in efficient generation of tunable vacuum ultraviolet (VUV) radiation (115.0-119.0nm) by nonresonant four-wave sum-mixing in Xe. The generated VUV intensity is greatly enhanced when Xe is matched with Ar. Calculations have been done to analyse the roles of phase-matching and to predict the optimum pressure ratio of Xe to Ar.

Concentration of Si-H₂ bond in porous silicon layer (PSL) affects its photolu-minescence (PL) intensity and peak wavelength PL emission characters of PSL associate with not only its micro-structure, but also the Si-H₂ band. So a stabilization of the emission intensity and the peak wavelength can be achieved by proper photochemical processing. A stable effective PL emission at wavelength as short as 570nm can be observed on PSL made by anodization method.

The particle and energy reflection coefficients of fusion α-particles which leak out from the plasma boundary in a fusion device and bombard the first wall with various incident directions are calculated by the newly-improved bipartition model for light ion transport. The influence of surface barrier upon the reflection of α-particles with low energy is investigated as well. The validity of bipartition model can be shown by the comparison of computational results with relevant experimental data.

Numerical calculations are used to study the initial temporal evolution of the wake-field produced by a short laser pulse. Results are compared to the previous quasi-static solutions. The usually adopted quasi-static approximation is found not appropriate for describing the wake-field generation at initial stages.

This paper reports the growth of pqre and Na, K modified lead barium niobate crystals and the measurement of their dielectric and structure properties. Exprimental results show that both pure and Na, K modified lead barium niobate crystals have growth striations. All the crystals belong to 4mm point group of
tetragonal system at room temperature. Their Curie temperature are 379°C, 389°C and 473°C, respectively.

Striation-free LiBa₂Nb₅O₁₅ (LBN) single crystal of good optical quality has been grown by Czochralski method. The crystal growth and dielectric, structural, spectral properties of LBN were measured. Experimental results show that LBN single crystal belongs to tetragonal tungsten bronze structure at room temperature. Experiments carried out with LBN powder samples have shown that this crystal has good second harmonic generation effect. At room temperature, the dielectric constant ₃₃ is about 87 and Curie temperature T_c, is about 586°C. A very ideal uniaxial conoscope image can be observed in LBN single crystal under polarizing microscope. In the range of 600 to 2600nm, the transmission of single crystal is about 75%.

The study of positron annihilation on amorphous 0.60AgI-O.25Ag₂O-0.15P₂O₅ has been carried out in the temperature range from 100 to 350K. The temperature dependence of average lifetime shows anomalous peaks at 208, 228, 325, 338 K indicating possible structure relaxation. Especially the last two peaks reflect the structural changes during pre-crystallization process of the amorphous ionic conductor. These results are consistent with that of ultrasonic attenuation and ionic conductivity experiments on the same samples.

The changes of electronic structure with the concentration x in BI structure NbC_x, are calculated by means of the LDF-LMTO-ASA supercell statistical method. It is shown that the trend of total density of states on the fermi Surface(E_F)changing with x is consistent with the results of experiments on the whole.

The effect of slow neutron irradiation at a low Auence of about 10⁸n/cm² on the microstructures of Bi-2223 polycrystalline samples was observed by transmission electron microscopy. By comparative study of the defect structures in a given area in one sample, we get evidence for the flux pinning enhancement by low Auence slow neutron irradiation.

A new series of 1222-type thallium-indium layered cuprate compounds (Tl, In)Sr₂(Nd, Ce)₂Cu₂O_z have been successfully synthesized in the pure or nearly pure form and identified by powder x-ray diffraction analyses. The structure of the compounds is directly related to that of Nb-1222 NbSr₂(Nd, Ce)₂Cu₂O_z, with a tetragonal body-center lattice. The lattice parameters are a=3.85Å, c=29.56Å for (Tl_0.7ln_0.3)Srz(Nd_0.5Ce_0.5)₂Cu₂O_z, and a=3.85Å, c=29.28Å for lnSr₂(Nd_0.75Ce_0.25)₂Cu₂O_z. Resistance measurements showed that (T1_1-xIn_x)Sr₂(Nd_0.75Ce_0.25)₂Cu₂O_z(x ≤ 0.8) are superconducting with Tc(onset)=30-40K .

The effect of annealing process in flowing nitrogen on the formation of super-conducting phases in Nd_1.85Ce_0.15CuO_4-y has been investigated. Two super-conductingphases with onset temperature T_cons of about 15 and 25K might be formed when the samples were annealed at various temperatures ranging from
850°C to 870°C and from 880°C to 920°C, respectively. The dependence of T_cons on the annealing temperature was reported.

A new method in the parabolic equation modeling of microwave propagation is developed to cope with the problem of radiowave propagation over irregular terrain in the presence of atmospheric refraction effects.

The photogravitationally restricted three-body problem in which the mass reduction factors of two primaries q₁, q₂ ∈ (-∞,1] is studied and the calculating formula of the location of coplanar libration points is given in this paper. As an application, the motion of cometary dust in the solar system and dust grain in binary AR Cas is also discussed.