Vol. 27, No. 5 (1978)
1978-03-05
CONTENT
1978, 27 (5): 487-495.
doi: 10.7498/aps.27.487
Abstract +
The possibility of using the optimization methods in realizing a given linear transformation of patterns by optical system is discussed. Furthermore, we have developed a method for characteristic expansion with discrete spectrum and also analyzed some problems pelated to concrete calculations.
1978, 27 (5): 496-507.
doi: 10.7498/aps.27.496
Abstract +
The phase compensated far field distribution of laser modes TEMm0 and TEM0l is analyzed. It is shown that the characteristics of the far field distribution is substantially improved.
1978, 27 (5): 508-515.
doi: 10.7498/aps.27.508
Abstract +
In this paper a universal real-time speech recognition system-RTSRS(01) is described. On the basis of the previous work[1], the parameters of a spoken command are normalized in the time domain. Using the binary spectrum as the final recognition parameters, which can largely reduce the amount of memory necessary for each reference command, and adapting a new method for calculating the separation between two spoken commands to be compared, it is possible to make the system RTSRS(01) capable of identifying single entities in a vocabulary of 200 items in real-time. The results of recognition for a specific speaker are as follows: 10 spoken Chinese digits-99.7%; 20 sentences (7 syllables for each)-99.7%; 100 phrases (4 syllables for each)-99.5%; 150 phrases (4 syllables for each)-99.3%; 200 phrases (4 syllables for each)-98.8%; 400 phrases (4 syllables for each)-97.7%. It has been shown by informal experiments that the system RTSRS(01) can be used to identify the vocabularies which include items with different numbes of syllables; furthermore, for the first 20 English digits and the names of BASIC statements, the correct recognition rate is also high.
1978, 27 (5): 516-523.
doi: 10.7498/aps.27.516
Abstract +
In this paper, a new method is proposed for the measurements of sound insulation of light structures using small samples. The sound source is placed in a reverberation room, and the receiving room is a small anechoic box. The arrangement of the measurement is described in betail. Several samples are measured and the results agree well with the mass law. The method does provide a useful alternative where the measurements for the samples of small dimensions with high transmission loss are required. Limitations of the equipment and evaluation of accuracy are also discussed.
1978, 27 (5): 524-532.
doi: 10.7498/aps.27.524
Abstract +
An approximate solution for the equivalent phase center of antenna on a plane ground and several related results have been given in this paper.
1978, 27 (5): 533-546.
doi: 10.7498/aps.27.533
Abstract +
In the present paper, a method of calculating scattering field by a spherical mirror is introduced. Three coordinate surfaces of the spherical coordinate system are used to surround the mirror and separate the space into three regions, in each of which the general solution have been worked out, respectively. Then by making use of the boundary-condition, we obtain a group of equations, by which the coefficients are determined. This equations are used for calculating the radiating field of spherical antennas. The analytic solutions are obtained.
1978, 27 (5): 547-553.
doi: 10.7498/aps.27.547
Abstract +
1. After transforming the zone axis [uvw] of a FCC crystal into [utvtwt] of its twin or [u′v′w′] of the HCP phase formed in it, it is possible to recognize immediately from these indices whether the electron diffraction pattern of the latter is distinct from that of the former.2. The qpndition for the twin to have a non-distinct pattern is: u(t2)+v(t2)+w(t2)>u2+v2+w2. 3. The condition for the HCP phase to have a non-distinct pattern is: u′,v′≠3n, u′+v′=3n. 4. As far as the low zone indices (u, v, w≤4) electron diffraction patterns of a FCC crystal are concerned, approximately 80% of the twin or HCP phase are not discernible by electron diffraction analysis.
1978, 27 (5): 554-558.
doi: 10.7498/aps.27.554
Abstract +
Superstructures are often observed in inorganic crystals, including many minerals and certain important solid state materials. In diffraction patterns of such crystals, superstructure reflections, which carry information of the structure details, are generally very weak. The common practice in structure determination is, therefore, to ignore the superstructure reflections at first, making use only of the strong pseudos-tructure reflections to find a pseudostructure to account for the essential structural features. The precise superstructure is then derived on its basis. However, this approach is complicated in consequence of the impossibility to derive the latter directly from the former by means of ordinary techniques of structure refinement. To overcome this difficulty, it is proposed in this paper that the phases of superstructure reflections can be derived directly from those of the pseudostructure reflections. This considerably simplifies the procedure of superstructure determination. Applications to practical structures confirmed the effectiveness of the method.
1978, 27 (5): 559-568.
doi: 10.7498/aps.27.559
Abstract +
In the presence of external sources, a superconducting weak link can be represented by a simplified model, consisting of a resistively shunted Josephson junction driven by a current source. We give in this paper, an analytical solution of the problem, in the case that the source current has both d. c. and a. c. components. As preliminary applications of our solution, we have also discussed square law detection and current steps of zero average voltage on the I-V characteristic, as the dimensionless a. c. component is small.
1978, 27 (5): 569-575.
doi: 10.7498/aps.27.569
Abstract +
This paper uses the Numbu method in Matsubara representation to extend the Eliashberg strong-coupling superconductivity theory for the case of spatial variance. The shell model solution for small particles is given.
1978, 27 (5): 576-582.
doi: 10.7498/aps.27.576
Abstract +
The structure of the high magnetic permeability Pe-Si-Al alloy containing about 10 percent Al and 5 percent Si has been investigated. By using the foil specimen technique of electron microscope, the structure of matrix was found as ordered fcc Fe3(Al, Si) phase, its lattice parameter being 5.70±0.03?. This value lies between the values of the lattice parameter of Fe3Si and Fe3Al. This explains that a proportion of the silicon atoms is replaced by the aluminium atoms. Three sets of electron diffraction patterns of the matrix combined with the precipitated phase were obtained and their orientation relationships determined.The carbon replica of the extracted precipitated phase in selected regions is diffracted by contrast in the electron microscope. The Fe3(Al, Sl) Cx phase is a cubie structure. It might be suggested that the Fe atoms occupy the positions of face centres, Al(Si) atoms occupy the cube corners, and the carbon atoms occupy the body centres.
