Bulletin Number Four 1985

Electr. Engrs., No. 165 and No. 167; Shannon, C.E.: ‘A Symbolic Analysis o f Relay and Switching Circuits', AIEE Trans., Vol. 57.) However, it was demonstrated that the most efficient radix for a computer is not the number 2 but e (= 2.71828) which is close to 3, and thus ternary system was suggested as an alternative to the binary. (Harvard Computation Laboratory: ‘Synthesis o f Electronic Computing and Control Circuits', Ann. Harvard Univ. Computation Lab., Vol. 27, p. 50, 1952; Morris, D.J . & Alexander ， W.: 'An Introduction to the Ternary Code Number System', Electronic Engineering, Vol. 32, p. 554 ， 1 960.) One disadvantage o f ternary circuits is that it requires more active elements than the binary one because o f the greater number o f compositions. During the performance o f decimal calculation, no matter it is in radix 2 or in radix 3, a code-to-code conversion is necessary. In order to remove this kind o f conversion, a denary logic is studied in the Physics Department. As VLSI is being developed rapidly, it becomes apparent that 10-valued logic system would be the most attractive alternative to binary system. From an engineering point o f view, one o f the most promising features o f denary logic system is the potential for the reduction o f the wiring complexity, at least it cuts down the interface for code conversion. We have already demonstrated how to use a single core which is conventionally operated 0 or 1 to memorize 0 to 10 instead o f using 4 cores in binary. (Ho, H.H.: 'Direct Storage o f Decimal Numbers by a Square Loop Core ’ ， Int. J. Electronics, Vol. 39 ， pp. 497-507, 1975.) Also, the arithmetic operation is more or less based on the idea as the paper and pencil manipulation o f decimal numbers. (Ho, H.H.: 'Denary System Arithmetic Operation', Int. J. Electronics, Vol. 54 ， pp. 625-641,1983.) Such an idea has already been demonstrated by experiments and it shows a good possibility o f using denary logic as another alternative to binary logic. (Ho, H.H. and Tsun ， T.O.: 'Denary Logic Arithmetic Processor' ， Int. J. Elec tronics, Vol. 57 ， pp. 307-331, 1984.) Therefore, we reckon that a challenging opportunity may be open in this area. Research on Musical Acoustics - S .Y .F en g Research on Pi-Pa acoustics started about five years ago in the Physics Department. This research has its origin in the laser optics research carried out at this University in the late 60's by Mr. L.K. Su and Professor B. Hsu, who started their nonlinear optics research at New Asia College on Farm Road. Later, in the early 70's, the centralization o f the three Colleges brought all the Physics staff under the same roof at the Science Centre and L.K. Su and S.Y. Feng collaborated on holographic spectroscopy. After the retirement o f Su, Feng concentrated on laser interferometry, which provided a new technique for the measurement o f very small vibration or de formation not observable by conventional methods. Feng chose musical instruments as the vibrating objects. When the object was excited, by an electro magnetic device, into a steady and periodic vibration, a laser hologram was taken. After darkroom pro cessing, the hologram was illuminated w ith a laser beam to reconstruct an image o f the original musical instrument. Superimposed on this image was a fringe pattern representing the 'mode' o f the vibration. During the past few years, a series o f measurements was performed on Pi-Pa and Cheng. The accumulated data showed a very interesting result. The sound waves produced by a Pi-Pa contain higher harmonics components which are much stronger than the funda­ mental. This is quite different from the behaviour o f western musical instruments. Whether this feature is common to most Chinese musical instruments requires continuous and more extensive research. Researchers on musical instrument acoustics can join hands w ith instrument makers in producing, hopefully, ideal and perfect instruments for the performers. No doubt, this w ill be a long and d ifficu lt journey. Nuclear Sciences and Cosmic-ray Physics - L.S. Chuang Nuclear Sciences (1) In 1973 the International Atomic Energy Agency (IAEA) donated a 14 MeV neutron generator and a complete set o f Ge(Li ) gamma-ray spectrometer to the Physics Department. They have been used largely for the following research: Elemental analysis: We have analyzed, by means o f neutron activation, more than two hundred Chinese medicines for the elemental contents o f protein, phosphorus, potassium and magnesium, and also the elemental contents o f ancient Chinese bronze seals. Through these studies, first-hand scientific information on the elemental constituents o f the Chinese medicines was gained and a further under standing o f the ancient Chinese bronze was made possible. Elemental analysis by means o f neutron inelastic scattering in bulk material is now in progress. Neutron spectrometry and dosimetry: We have developed a unique method for neutron spectrometry. We are now studying the neutron dosimetry, using large-area plastic scintillators. Nondestructive testing o f material defects and evaluation o f precious stones: We have developed a method o f detecting the scatterer material defects, using the 14 MeV neutrons and a pulse-shape analyzer 28 RECENT DEVELOPMENTS