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Vol. 29, No. 2 (1980)

1980-01-20
CONTENT
THE STOCHASTIC MODELS FOR NON-EQUILIBRIUM SYSTEMS AND FORMULATION OF MASTER EQUATIONS
YAN SHI-JIAN, LI ZHAN-BING
1980, 173 (2): 139-152. doi: 10.7498/aps.29.139
Abstract +
In this paper we present clearly a set of postulates on probabilities which are the basis of the nonlinear master equations and multivariate linear master equations appeared in non-equilibibrium statistical physics. By using the methods of probability theory, we deduced these master equations from our general postulates. We further discussed the conditions under which the master equations are consistent with the macroscopic kinetic equations. Finally, we discussed the fluctuation in Brusselator model using multivariate linear master equation approach and made a preliminary explanation on the appearance of dissipative structure through fluctuation.
UNITARY TRANSFORMATION AND GENERAL LINEAR TRANSFORMATION BY THE OPTICAL METHOD (Ⅳ)——THE PATTERN RECOGNITION AND PROJECTION OPERATOR
HUO YU-PING
1980, 173 (2): 153-160. doi: 10.7498/aps.29.153
Abstract +
In this article, it has been pointed out that the pattern recognition is the representation transformation in pattern space. As it is well known, in Hilbert space, the representation transformation is realized by the unitary operator, so it is more suitable to use the optical method for pattern recognition. Further more, we have discussed the method with which one can construct the optical system only from the characteristic patterns, In reality, this problem is to realize the projector by optical method. We also have advanced the optimization method in [3].
DETERMINATION OF THE SIZE DISTRIBUTION OF ATMOSPHERIC AEROSOLS BY MEANS OF MEASUREMENT OF OPTICAL ATTENUATION
TAO RONG-JIA
1980, 173 (2): 161-172. doi: 10.7498/aps.29.161
Abstract +
In this article we made a theoretical investigation on determination of size distribution of atmospheric aerosoils by means of measurement of optical attenuation. We showed that the Predholm integral equation of the first kind has only one solution when attenuation cross-section is given by Van de Hulst approximate equation. We thus proved that remote sensing of atmospheric aerosoils by variation of optical wave lengths is possible. We also studied the problems of inversion computation, analyses of errors, effective information and selection of the optimal optical wave lengths associated with this remote sensing process.
PECULIARITIES EXHIBITED BY ALUMINIUM-SILVER ALLOY IN THE PROCESS OF FATIGUE LOADING
WANG ZHONG-GUANG, XIA YUE-BO, HUANG YUAN-SHI, GE TING-SUI
1980, 173 (2): 173-181. doi: 10.7498/aps.29.173
Abstract +
Torsional fatigue experiments were performed with Al-7.27% Ag alloy in the quenched state. The △E-N curves were determined under various torsion strains and metallographie observations were made on the specimen surface after various numbers of stress cycles.Experimental results showed that, when the torsion strain is small, △E was found to decrease with the increase of stress cycle N. The change of the △E-N curves is similar to those previously reported for Al-Cu and Al-Mg alloys under lower torsion strains. However, when the torsion strain is large, AE decreases slightly at the beginning, increases subsequently to some higher value, and drops again until the specimen is fractured. The shape of the △E-N curves is very different from those of Al-Cu and Al-Mg alloys at same strains. The metallographie change of the specimen surface during cyclic deformation was found to be divided into two distinct stages. In the initial period of fatigue loading, fine straight slip lines are homogeneously distributed within certain grains. However, some of them suddenly become highly concentrated and prominent after a certain number of cycles. With increasing fatigue cycles, newly generated localized slip bands occur successively between the existing ones. This observation is markedly different from that observed on pure aluminiun and the quenched Al-Mg alloys, where only the existing slip regions appeared to become broader with the increase of cyclic straning. In addition, fatigue cracks were frequently observed to initiate and propagate along grain boundaries.The results obtained was discussed in terms of the electrical interaction of silver atoms with dislocation and the cutting effect of the to-and-fro moving dislocations though spherical clusters of silver solute atoms.
THE CRYSTAL STRUCTURE OF (Ni, Co)3Al4 IN THE Al-Ni-Co TERNARY SYSTEM——A NEW VACANCY CONTROLLED ALLOY PHASE
LU XUE-SHAN, LI FANG-HUA
1980, 173 (2): 182-198. doi: 10.7498/aps.29.182
Abstract +
(Ni, Co)3Al4 is a ternary phase in the Al-Ni-Co system, the homogeneous range at room temperature being 55-58.5 A/0 Al, 26-35 A/0 Ni, and 10-15.5 A/0 Co. It belongs to the cubic system with space group Oh10-Ia3d. There are 112 atoms per unit cell, the lattice spacing at room temperature being α = 11.3962?.This structure may be considered as a superlattice built up by stacking together 64 CsCl type fundamental structural units. Among these structural units, there are 16 ‘Centre' positions left vacant in order. They occupy the 16(b) equivalent positions forming 16 octahedral voids. The ‘Corner' positions 16(α) and 48(f) are all occupied by Al atoms, while the ‘Centre' positions 48(g) are occupied at random by Ni and Co. Due to the existence of the voids, the positions originally at cube corners and centres are displaced somewhat, the parameters being xf = 0.010, xg = 0.369.Prom the homogeneous range of this alloy phase and the distribution of the various atoms in the structure, the ideal stoichiometric formula of this alloy phase may be written as (Ni, Co)3Al4. There are 16 formula weights per unit cell.
ELECTRON DIFFRACTION INVESTIGATION OF AMORPHOUS Gd-Co ALLOY FILMS
GAO JUN-JIE, LI FANG-HUA, WANG YIN-JUN, TENG CHEN-MING, CHANG LONG-CUN
1980, 173 (2): 199-204. doi: 10.7498/aps.29.199
Abstract +
Electron diffraction technique was used to study the structure of various amorphous films of Gd-Co alloy and Lorentz electron microscopy was used to observe the related magnetic structure. Seven halos could be seen clearly in all the electron diffraction patterns obtained and the two smallest halos were located in the range s-1 (s = (2sinθ)/λ). Magnetic bubbles or in-plane domain structures wereobserved in these amorphous films. For amorphous alloys of this type consisting of two elements, such as rare-earth and transition metals with a large difference in atomic radius, we showed how to derive directly and qualitatively the relative co-ordination number of nearest neighbours between rare-earth metal atoms, - between transition metal atoms, and between rare-earth and transition metal atoms, merely from the diffraction intensity profiles in the range s-1. The influence of phase separation in the film on the magnetic anisotropy was also discussed.
AN ELECTRON TRANSPORT THEORY OF THE CAVITY IONIZATION
LOU ZHENG-MING
1980, 173 (2): 205-213. doi: 10.7498/aps.29.205
Abstract +
In the present paper, the electron transport equation has been applied to study the phenomena of cavity ionization. It has been shown that the effect of the cavity on the energy spectrum of electron inside it can be attributed to an equivalent electron source uniformly distributed in the cavity. A formula for the energy spectrum of the equivalent electron source is obtained. The deposited energy of the equivalent electron source in the cavity of a plate chamber has been calculated. As compared with the Spencer-Attix theory, the present theory is shown to be in better agreement with experiment for describing phenomena of the cavity ionization.
ON THE LOW FREQUENCY DRIFT WAVE AND THE PSEUDOCLASSICAL DIFFUSION
ZHANG CHENG-FU
1980, 173 (2): 214-224. doi: 10.7498/aps.29.214
Abstract +
In this paper, the relationship between the low frequency drift wave and the empirical law of anomalous transport in Tokamak the pseudo-classical diffusion is discussed. We show that, it is the collisionless drift wave, rather than the dissipative one, which corresponds to the pseudoelassical diffusion. If the linear unstable collision-less drift wave is saturated mainly by the quasi-linear relaxation process, it can lead to a diffusion of the pseudo-classical type. The estimated diffusion coefficient agrees with experiment within an order of magnitude. The range of the parameters in which the above mentioned mechanism may be effective is discussed.
THE LONGITUDINAL RESISTIVITY OF A MAGNETIZED PLASMA
WU JING-SHENG, CAI SHI-DONG
1980, 173 (2): 225-232. doi: 10.7498/aps.29.225
Abstract +
Longitudinal electric resistivities of magnetized and unmagnetized plasmas are discussed based on appropriate kinetic equations. It is found that (1) for an isotropic plasma the resistivity calculated based on the kinetic equation including magnetization is about 1.5 time greater than that obtained in the theory without including magnetization, and (2) for an anisotropic plasma, the magnetized resisitivity is proportional to Te⊥Te‖-5/2 whereas the unmagnetized resistivity is proportional to Te⊥-1Te‖-1/2. The discrepancy is mainly due to the effect of the ambient magnetic field on the electron trajectory. It is also argued that the effect of dynamic shielding can be neglected in comparison with static shielding. A qualitative explanataion is given.
A VARIATIONAL PRINCIPLE FOR THE EQUILIBRIUM OF A FREE-BOUNDARY PLASMA
WANG DE-YU
1980, 173 (2): 233-240. doi: 10.7498/aps.29.233
Abstract +
In the free-boundary case, the extremum of the potential functional is found from the variational principle. Thereby the equation and boundary conditions required for plasma equilibrium are derived. The Euler equation of the relevant functional is the magnetic surface function equation with the condition of free boundary. A variational functional suitable for numerical computation is given. This functional corresponds to a boundary value problem with an equal-value surface boundary condition. For the case of a conducting wall of simple geometry (i.e., a rectangular wall), numerical computation has been carried out by using the Ritz method.
FORMATION OF HARD BUBBLES UNDER BIAS PULSE FIELD
NIE XIANG-FU, LIU YING-LIE, HAN BAO-SHAN
1980, 173 (2): 241-246. doi: 10.7498/aps.29.241
Abstract +
The conditions under which hard bubbles form in the process of gererating bubbles by a low frequency pulse field were experimentally studied. It was found that the percentage P of hard bubbles decreases quickly with increasing amplitude Hp of the bias pulse field. There was evidence for the existence of a critical value Hpo, such that when Hp≥Hpo, all bubbles generated were soft ones.
BRIEF REPORT
DETERMINATION OF X-RAY POWDER DIFFRACTION DATA FOR SODIUM STRONTIUM BARIUM NIOBATE SYSTEM
GUO CHANG-LIN
1980, 173 (2): 247-251. doi: 10.7498/aps.29.247
Abstract +
The X-ray powder diffraction patterns of various compounds of sodium strontium barium niobate system were obtained with a counter diffractometer and a Guinier focusing camera using CuKα radiation. The detail indexed powder diffraction data for Ba2NaNb5O15, SrBaNaNb5O15 and Sr2.05Na0.90Nb5O15 were given. These data may replace those presented in the JCPDS X-Ray Powder Diffraction Standards Data Pile (Cards No. 23-654, 27-1408, 27-1409, 27-787).
AN INVESTIGATION OF DIVALENT IODATES AND THEIR COMPLEX SALTS
LIANG JING-KUI, YU YU-DE, DING SHI-LING
1980, 173 (2): 252-256. doi: 10.7498/aps.29.252
Abstract +
The phase transitions, thermal stabilities and crystal structures of strontium iodate, barium iodate, calcium iodate, zinc iodate and cadmium iodate have been investigated by means of X-ray powder diffraction and thermal analyses. The possibilities of formation of complex compound between divalent iodates have been studied. The stability of hydrated divalent iodates is expected to be related to the electronegativity of the corresponding cations.
THERMAL NEUTRON INELASTIC SCATTERING OF PALLADIUM HYDRIDES (PdHx)
WU XIAN-NAN, CHEN GUI-YING, CHENG ZHI-XU, RUAN JING-HUI
1980, 173 (2): 257-259. doi: 10.7498/aps.29.257
Abstract +
The local modes (or optical branches) of the PdHx samples for x = 0.17 and 0.67 have been measured respectively with the Beryllium Filter Detector Spectrometer. It was observed that the position of the peak for the PdH0.67 is about 5 meV lower than that of the PdH0.17. The relation between the softening of local modes and the supercodue-tivity has been discussed qualitatively.
THEORY OF HIGHER ORDER CHROMATIC ABERRATIONS
XUE MING-QIU, LIN DA-JIAN
1980, 173 (2): 260-264. doi: 10.7498/aps.29.260
Abstract +
In this article, we discuss the changes of the coordinates of the pupil and the object plane caused by the Seidel aberrations of the front groups in the optical system, and also the effect of these changes on the chromatic aberrations of the back groups, i.e., the theory of derivative higher order chromatic aberrations.
DEFECTS ETCHING PITS OBSERVATIONS AND ANALYSES ON EPITAXIAL SILICON CLEAVAGE SURFACE
CAI TIAN-HAI
1980, 173 (2): 265-269. doi: 10.7498/aps.29.265
Abstract +
In this paper results of observation using the Wright etchent on epitaxial silicon (111) cleavage surface are described. On silicon cleavage surface the etehent reveals stacking faults, dislocations, S-pits and other etch pits. Some of the buried stacking faults are also observed.
AN EMPIRICAL EQUATION FOR OPTICAL ORIENTATING CRYSTALS WITH LARGE OPTICAL AXIS ANGLES
XIAO CHAO-LIANG
1980, 173 (2): 270-272. doi: 10.7498/aps.29.270
Abstract +
In this note, the isogyres width of the interfuence figure in a convergent polarizing microscope is considered. Due to the occurence of this width, the angle through which the isogyres is brought from the black cross to the position just beyond the view field of a polarizing microscope would be increased. By taking into account this effect, the pricision of optical. Orientating trick crystal with large optical axis angle and high refraction index can be enhanced substantially.