Vol. 26, No. 5 (1977)
1977, 26 (5): 187-192. doi: 10.7498/aps.26.187
The Gd-Co films reported here were prepared by radio frequency sputtering and have been proved to have uniaxial anisotropy perpendicular to the film plane. Electron diffraction results show that these films are amorphous. Also, electron probe analyses show that these films are of uniform composition. Magnetic domains have been observed and hysteresis loops measured, using Kerr's apparatus. It was found that with suitable sputtering conditions, at remanence such films exhibit stripe domains, which, when acted on by a suitable external field perpendicular to the film plane, can transform into bubble domains.
1977, 26 (5): 193-198. doi: 10.7498/aps.26.193
In this article a method incorporating the information yielded by high resolution electron micrographs and the corresponding electron diffraction patterns is proposed for the determination of crystal structures. Using this method it is possible to solve the problem of extracting structure amplitude moduli from electron diffraction data and also to solve the phase problem that commonly occurs in diffraction analysis. The resolution of the structure image so obtained may be higher than that of the original electron micrographs and may approach the diffraction limit.
1977, 26 (5): 199-207. doi: 10.7498/aps.26.199
The phase transitions of LiIO3 crystals have been investigated by the methods of DTA, heat-treatment at constant temperatures, and high-temperature X-ray diffraction. Our experimental results show that the γ phase of the crystal appears as an intermediate metastable phase such that α←→γ→β, and it can exist only in the temperature range 230-300℃ within a period of several hours to a few days. Upon crystallization from the melt, a new phase or rather a group of new phases never mentioned previously in the literature has been revealed by X ray diffraction studies. We designate them as δ-LiIO3. The difference in their structures is probably related to the cooling condition. After subsequent cooling to 200-180℃, the δ phases transform into the α phase. However, if the temperature is raised again before δ→α takes place, then δ directly transforms into β after reaching the γ→β temperature range. The results of our investigation may be summarized in the following diagram:
1977, 26 (5): 208-214. doi: 10.7498/aps.26.208
A search for heavy particles of positive single charge in hydrogen and deuterium samples has been carried out, with an electromagnetic separator, by measuring the charge mass ratio of the particles. The impurity background was rejected by the absorption methed. A specially designed proportional counter with very thin windows was used to detect and measure the energy of the particles. The mass region studied was 65-220 Mp (Mp is the mass of the proton). Results show that in natural water the upper limits of concentration for heavy particles of positive single charge with masses of 65-148 Mp and 148-220 Mp are less than 2×10-17 particles/H atom and 5×10-17 particles /H atom respectively.
1977, 26 (5): 215-224. doi: 10.7498/aps.26.215
In this paper Cohn's theory on directly coupled resonator filters is extended to one-quarter-wavelength coupled filters, thus theoretically unifying the two different types of microwave filters. The frequency response transformation from a lowpass to a band pass filter is given, the change of the filter susceptance with frequency being taken into account. Experimental results show that, using formulas derived in this paper for filter designing, the expected bandwidth and stop-band attenuation are in better agreement with practice. Finally, a method for eliminating asymmetry in frequency characteristics is discussed.
1977, 26 (5): 225-231. doi: 10.7498/aps.26.225
The normal modes which can arrive at a receiver are summed according to energy, and an expression for the averaged intensity is then obtained by averaging over the source and receiver depth. The space structure of the averaged sound intensity is discussed with this expression.
1977, 26 (5): 232-242. doi: 10.7498/aps.26.232
A new method used for analysis of infrasound signals recorded on paper in the as a function of time is presented. The principle and technique of this method are described, and some spectrograms processed by computer are presented. The DGC-FORTRAN-IV program used for this method is also given.
1977, 26 (5): 243-249. doi: 10.7498/aps.26.243
The formulae for calculating nuclear moments of inertia with the particle-numbes-conserving method for treating pairing forces are presented. Taking 170Yb and 169Yb as typical examples, the even-odd difference of the moments of inertia and the dif-ference in moment of inertia between excited bands and the ground band are treated with this method, which automatically takes the blocking effect into account. The calculated results agree relatively well with the experiments.
1977, 26 (5): 250-258. doi: 10.7498/aps.26.250
By assuming the weak lens focal length expression to be the first term in a power series, a simple and accurate formula can be derived for the objective focal length of a magnetic electron lens. This extended weak lens formula remains accurate even at strong excitations. This technique has also been applied to some of the other optical parameters. Where this approach was not practical, purely empirical formulae were derived. The constants in the for mulae were determined using data published by previous authors. The accuracies of the formulae are sufficient for most engineering design purposes.
REDUCED SPINOR FORMALISM BY MEANS OF TETRAD CALCULUS WITH APPLICATION TO YANG'S GRAVITATIONAL FIELD EQUATIONS
1977, 26 (5): 259-273. doi: 10.7498/aps.26.259
In this paper, a reduced spinor formalism for the space-time manifolds is given. In particular, we show that the Newman-Penrose equations are redundant, and six of these equations can be omitted. As an application to Yang's gravitational field equa-tions, all type O and some type N "pure spaces" have been obtained.
EXPERIMENTAL INVESTIGATION OF THE MECHANISM OF CAVITATION EMULSIFICATION EMPLOYING HIGH-SPEED PHOTOGRAPHY
1977, 26 (5): 381-388. doi: 10.7498/aps.26.381
In this work results are given for the experimental investigation of the me-chanism of cavitation emulsification by means of high-speed photography. The results show that: 1) Two fundamental types of cavitation emulsification occur simultaneously at the moment of a single cavitation bubble collapse. It thus appears that: emulsifica-tion is induced by the shock waves generated in liquids at the moment of cavitation bubble collapse; 2) In contrast with the "suction" model suggested by Nedouzhii, the process of cavitation emulsification would be better described by a "crushing" model.
1977, 26 (5): 389-396. doi: 10.7498/aps.26.389
A model for speech recognition by computer is suggested. In which a new method of pattern normalization in the time domain is presented. A program for recognizing spoken sounds has been developed on a Varian 620/L computer. Finally, a set of ex-perimental results is given, the correct recognition rate being grater then 99%. It is shown that this new method can be used in certain automatic control systems.
1977, 26 (5): 397-410. doi: 10.7498/aps.26.397
On the basis of the structural model of stratons, we discuss semi-leptonic decays of (1/2)+ baryons and elastic and quasi-elastic neutrino reactions, using the effective Ha-miltonian of weak interaction for stratons and leptons in  and the (1/2)+ baryon wave functions in  and the parameters determined by electromagnetic processes in . The theoretical results of the semi-leptonic decays are in good agreement with the experimental results. The axial-vector form factor of △S = 0 processes and the total cross-sections of νμ+n→p+μ- agree with experiments within reasonable error. The axial-vector form factor of △S = 1 processes and the total cross-sections of νμ+p→Λ+μ+ also agree with the rough experimental data available.In particular, it is of interest to point out that, in our discussion, all the parame-ters involved were determined in , no new parameter has been introduced.
1977, 26 (5): 411-416. doi: 10.7498/aps.26.411
The empirical formula j=Σn jnsin nφ for a superconducting Dayem bridge is proved using Green's function and the two-gap model of the bridge. A quantitative explanation for the observed height of the microwave induced step is presented. This paper also gives the sufficient condition for the empirical formula of a superconduc-ting bridge, and the dependence of Josephson current density on bridge length is discussed.
1977, 26 (5): 417-426. doi: 10.7498/aps.26.417
In this paper, a generalized Ohm's Law of unsteady state in partially ionized plasma is derived. Various appropriate expressions under concrete physical conditions are analysed. When plasma approaches fully ionization, the generalized Ohm's Law reduces to the form given by Spitzer; and when partially ionized plasma reaches steady state, the generalized Ohm's Law reduces to the form given by Cowling and Любимов. Finally, this Ohm's Law is applied to certain problems on plasma a. c.resistivities, dispersion relations and diffusions, etc.
PHYSICAL METHOD OF GROUP REPRESENTATION THEORY (Ⅱ)——THE QUASI-STANDARD BASES OF PERMUTATION GROUP AND THE GELFAND BASES OF UNITARY GROUP
1977, 26 (5): 427-432. doi: 10.7498/aps.26.427
This paper analyses the contradictions which would appear when one applies the traditional theory of group repesentation to gf-the permutation group on state indicies. It is pointed out that when repeated state indicies occur, the permutation operator of gf will become undefined. According to , we generalise naturally the concepts of the irreducible bases for such case and give a unambiguous definition of the so called quasi-standard bases of group gf. Futhermore we have proved that the quasi-standard bases of group gf are just the Gelfand bases of group SUn. Hence the eigenfunction methodcan also be used to calculate the Gelfand bases of group SUn.