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Vol. 13, No. 6 (1957)

1957-03-20
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CONTENT
AN APPROXIMATE METHOD FOR DETERMINING THE PLANE STRESS OF ORTHOTROPIC MATERIAL
HAO TUNG-SHENG
1957, 39 (6): 452-462. doi: 10.7498/aps.13.452
Abstract +
In this paper, an approximate expression for solving plane stress problem of orthotropic material is worked out based upon the procedures of Lecknitzky's work. For the purpose of applications, three simple examples are given, namely: (1) The bending of beam with circular hole, ( 2 ) circular hole in a plate under simple tension, ( 3 ) elliptic hole in an infinite plane with uniformly distributed pressure acting on the edge of hole.
AN INVESTIGATION OF Ag-Au-Zn ALLOYS WITH 50 AT. % Zn
LIU YI-HUAN, HSU CHEK-CHIA
1957, 39 (6): 463-482. doi: 10.7498/aps.13.463
Abstract +
A β″ superlattice structure, with the ideal stoichiometrical formula AgAuZn2 and isoinorphous with that of Heusler alloys, has been found existing over a quite wide range of composition. It is, in fact, a superstructure of the β′ ordered structure. Its formation is accompanied by a sudden lattice contraction. The effect of gradual substitution of Ag by An on the atomic distribution has been stndied systematically. It is shown that the Au atoms introduced simply replace the Ag atoms more or less in a random manner, the positions of Zn atoms not being affected. Tho decrease of the degree of order as deviating from the stoichiometrical formula is not merely due to the deviation from the ideal chemical composition; some disordering among the Ag and Au atoms also occurs. High temperature investigation of Ag-rieh alloys shows that the temperature of β′-β transformation increases with Au content and that the β-phase structure exists only at high temperatures. The presence of even a minute amount of Au stablizes the β′ structure obtained by quenching very remarkably. On the other hand, the β′ structure of Au-rich alloys persists from room temperature probably to the melting point.
THE ELECTRIC MULTIPOLE INTERNAL CONVERSION INDUCED BY NEUTRON TRANSITION
TZU HUNG-YUAN
1957, 39 (6): 483-499. doi: 10.7498/aps.13.483
Abstract +
The effect of the anomalous magnetic moment of the nucleon on the value of the internal conversion coefficient is investigated.The parts played by the sealer and tho longitudinal photons in the process of the internal conversion are first discussed. The retarded interaction between the charged particles with anomalous magnetic moment is derived by the correspondence method. The results obtained is then verified by the quantum electrodynamical treatment. The retarded interaction thus obtained is then applied to the calculation of the internal conversion coefficient. It turns out, that the anomalous magnetic moment of the nucleon has negligible influence upon the coefficient of the magnetic conversion and the coefficient of the electric conversion induced by the proton transition. However, the anomalous magnetic moment of the nucleon does cause considerable modification of the coefficient of the electric conversion induced by tho neutron transition, contrary io the conclusion arrived a,t by various authors. The problem of the gauge transformation is discussed and the errors contained in the treatment given by these authors are pointed out.
ON THE TRIGGERING PROCESSES OF SCHMITT CIRCUIT AND THE ACCURACY OF SUCH CIRCUITS IN MEASURING THE AMPLITUDE OF SHORT PULSES
HSIX HSIEN-CHIEH
1957, 39 (6): 500-514. doi: 10.7498/aps.13.500
Abstract +
The triggering processes of some types of Schmitt circuit, have been investigated. Their switching speeds have been calculated and checked by experiments. The main results are as following:(l)The switching speed of an ordinary d. e. coupled Schmitt circuit is rather slow.(2)The use of break-away diode in the Schrnitt circuit) shortens the triggering process considerably.(8)With other conditions unchanged, the switching spaed of an a. c. coupled Schmitt circuit is 3 times faster than a d. c. coupled Schmitt circuit. Combined use of (2) and (3) will greatly increase the switching speed of the circuit,hence this circuit is particularly suited for fast counting work.The accuracy of these circuits in measuring the amplitude of short pulses is also discussed in the paper.
FREE ENERGY OF A SOLID SOLUTION ON A FACE-CENTRED CUBIC LATTICE
TIN HOU-CIIAKG, TSIAO TUNG-KIANG, CHANG TSUNG-SUI
1957, 39 (6): 515-524. doi: 10.7498/aps.13.515
Abstract +
This paper applies Kirkwood's method for calculating the configurational free energy E of a solid solution to a solid solution AB3 inhabiting a face-centred cubic lattice. In this method, the free energy F is expressed as a series in (kT)A-1, and our calculation goes as far as the coefficient of (kT)-4. If the order of the solid solution is denoted by S and the free energy on neglecting 0(kT)-n by Fn, the relation between Fn and S are found to depend on n in a marked manner. In particular, F3 and F5, have always a minimum at S=0, implying no superlattice may exist. The foregoing is actually nothing but an indication of the slow convergence for the expansion of F in (kT)-1. On expressing F as a series in η≡exp{-(VAA+VBB-2VAB)/kT}-1 where VAA, VBB and VAB are interaction energies between AA, BB and AB pairs of nearest neighbours and denoting by Fn′ the free energy on neglecting O(ηn) , we find that F2′ and F3′ do not give us any superlattice, but F4′, F5′ do. In fact, from F4′, F5′, we get a sudden change of S accompanied by a latent heat, just as in the earlier theories. F4′, F5′ behave similarly, so we may hope they approximate the actual free energy.
CONFIGURATIONAL PARTITION FUNCTION OF BINARY SOLID SOLUTIONS
WANG TEH-MOU, HSU HOU-GHANG, CHANG TSUNG-SUI
1957, 39 (6): 525-542. doi: 10.7498/aps.13.525
Abstract +
The present paper continues an earlier investigation of the application of Meyer's theory of a gas mixture of two components to a solid solution AB inhabiting a lattice of the type AB by considering the A. atoms inhabiting the two different sublattices as forming two different components. It is proved that the different irreducible cluster integrals are linear functions (and hence the free energy of the solid solution) of coordination numbers of the type ∑λabλa′b′λ……, where a, a′,…, b,b′… are different sites on the two sublattices (say a and β sublattices) and λab is a neighbour matrix defined by λab=1 when a, b are nearest neighbours =0 if otherwise,the product in (1) is irreducible with respect to the suffices (i. e. not divisible into parts with one or no suffice in common) and the summation is taken over all positions of a, a′,…,b b′,…, (a, a′, a",… as well as b, b′… being always different). Galling such coordination numbers as z1,z2,…and writing the free energy F of the solid solution as f0+z1f1, z2f2+…,(2) we point out that these Fi may be calculated from the free energies of the same solution, but now with the sites falling into groups each of which contains a small number of sites and does not contain sites which are neighbours of sites belonging to a different group. Since F of these solid solutions may be found easily (without approximations), we succeed in getting the required free energy F. Of course, this is an approximate method of calculating F, since we can not find the various Fi at one stroke.It is finally pointed out that such a method allows extension to lattices of different structure, to components more than two, to include interactions between next nearest neighbours, etc.
ON THE REFLECTION ON TRANSPARENT PHOTOCATHODES
ZS. NARAY, M. TOTH
1957, 39 (6): 543-546. doi: 10.7498/aps.13.543
Abstract +
For the investigation of the reflection on transparent photocathodes we worked out a comparative method. By this method the absolute values of the common reflection coefficient of photocathode and glass envelope could be determined. Investigating a generally used type of photomultiplier (type RCA-5819) we found it to show a comparatively high reflection-50 per cent-in the maximum of sensitivity.