Journal and Proceedings of
The Royal Society of New South Wales
Volume 115 Parts 3 and 4 [Issued February, 1983]
CONTENTS
| AUTHORS & TITLES | PAGES |
| McMinn, A., Late Permian Acritarchs from the Northern Sydney Basin | 79-86 |
| Pollack, John, K., The Ethical Problems of the Modern Scientist | 89-90 |
| Orme, W.J., Privacy and Modern Science and Technology | 91-94 |
| Warren, B.A., Understanding the Cancer Process: Some Aspects of the Spread of Cancer in Man and Experimental Animals [Presidential Address, 1982] | 95-100 |
| Thesis Abstracts | |
| Barry, J.M., Multi-dimensional Neutron Diffusion | 101 |
| Trigg, M.B., Stabilities of compounds and Reaction Mechanisms in the Ti-Si-O-N System | 102 |
Vol 115 parts 3-4 pp.79-86
Late Permian Acritarchs from the Northern Sydney Basin
A. McMinn
Abstract. Five species of spinose acritarchs were encountered in the Late Permian coal measure sequences of the northern Sydney Basin. They occur both in those units previously thought to be marine, such as the Denman Formation, and occasionally in those directly associated with coal seams, e.g. the Middle River Coal. Mehlisphaeridium sp. cf. M. fibratum Segroves 1967 has a restricted stratigraphic range and is useful in correlating coal bores throughout the basin; the other species are either uncommon or range throughout the Late Permian sequence. Ulanisphaeridium is described as a new genus and U. berryense is described as a new species.
Vol 115 parts 3-4 pp.89-90
The Ethical Problems of the Modern Scientist
John K. Pollack
[Address presented to the Symposium on "Ethical Problems of Modern Science and Technology, conducted by the Royal Society of New South Wales, 4th November, 1981]
[No Abstract]
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Vol 115 parts 3-4 pp.95-100
Privacy and Modern Science and Technology
W.J. Orme
[Address presented to the Symposium on "Ethical Problems of Modern Science and Technology, conducted by the Royal Society of New South Wales, 4th November, 1981]
[No Abstract]
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Vol 115 parts 3-4 pp.95-100
Understanding the Cancer Process: Some Aspects of the Spread of Cancer in Man and Experimental Animals
B. A. Warren
[Presidential Address delivered to The Royal Society of New south Wales at Science Centre, Sydney, April 7, 1982]
Abstract. The course of the illness in an untreated patient with cancer depends upon the cell of origin of the cancer and the organ in which the cancer arose. Although there are certain general principles concerning spread, malignant tumours comprise a large number of separate diseases rather than a single entity. Removal of the primary tumour (i.e. the tumour in the organ where it first appeared) can usually be achieved and it is the secondary deposits that prove resistant to removal by surgery or treatment by other means. The way these secondary deposits develop is therefore basic to the understanding of the cancer process as a whole and is needed for a rational approach to therapy. Many malignant tumours spread via the blood stream by way of the release of tumour cells into the circulation and the primary malignant tumour must reach a certain stage in development and size before tumour cells are released in significant quantities.
Vol 115 parts 3-4 p.101
Multi-dimensional Neutron Diffusion
J.M. Barry
[Abstract of Thesis submitted for the Degree of Doctor of Philosophy at the University of Wollongong]
The numerical solution of time dependent neutron diffusion approximation to the transport equation is of vital interest to those concerned with reactor design and safety. The growth of modern computing power has increased the scale with which computations may be undertaken. To exploit these electronic advances fully, however, it is necessary to review existing numerical approaches and substitute more efficient techniques wherever appropriate.
This work first summarises an approach typical of the conventional method of solution. It subsequently concentrates on the heart of the method, namely the solution of very large sparse systems of linear equations. A new numerical approach for their solution is formulated. This essentially seeks a splitting for the iteration matrix which makes the iterative process more implicit. The role that 'experimental mathematics' and computer graphics played in its evolution is discussed. The method has three other possible applications. Two of these are pursued here. Of these secondary applications, the acceleration of convergence in energy has tremendous potential for thermal reactor studies.
Various aspects concerning the behaviour of the new iterative approach are observed. The method is tested extensively on a number of reactor configurations which demonstrate several aspects of design and modelling techniques. The implicit approach is contrasted and compared with relaxation and conjugate gradient methods. Considerable attention is devoted to the efficient implementation of the three iterative schemes on computers with virtual memory.
Traditionally, a secondary acceleration of the iterative technique is achieved with a variational approach. Several modern variations of this, with linear approximating functions instead of constant rescaling factors.are considered. The scheme requires the solution of a reduced system of linear equations. Matrix properties of the reduced system are considered, and methods of their solution discussed.
Justification for the secondary acceleration is analysed with a Fourier approach. The applicability of each scheme to the three basic iterative methods is considered by analysing the reduction of frequency components of error in the solution estimate. Predictions from theory are then compared with results on several reactor geometries, with and without the secondary acceleration.
Vol 115 parts 3-4 p.102
Stabilities of Compounds and Reaction Mechanisms in the Ti-Si-0-N System
Mark Brian Trigg
[Abstract of Thesis submitted for the Degree of Doctor of Philosophy at the University of New South Wales, Kensington, N.S.W.]
Silicon nitride had been known as a chemical compound for a number of years. In 1960 the Admiralty Materials Laboratory, in the United Kingdom, developed methods for its fabrication into functional shapes. Since then a great deal of effort has been directed to the use of silicon nitride and related materials in diesel engines for pre-ignition chambers, pistons, combustion chamber liners, nozzle guide vanes, blades, heat exchangers and thermal and acoustic insulation. In spite of these successes, there have been problems in the fabrication of nitrogen ceramics because of the low sintering rates of covalently bonded materials.
An important development in the field of nitrogen ceramics was the finding that in the structure of silicon nitride, part of the silicon content could be replaced by aluminium and part of the nitrogen by oxygen. This gave rise to the sialons. The aim of the present research was to study the effect of titanium in the Si-O-N system, that is to examine the system Ti-Si-O-N. Attention was concentrated firstly on reaction mechanisms and the stability of the compounds formed. Techniques employed included X-ray diffraction, scanning electron microscopy, energy dispersive X-ray analysis and optical microscopy.
Thermodynamic calculations provided an analysis of the energy relations in the system. Particular attention was devoted to the effects of the gas phase. The results of the calculations provided further insight into reaction mechanisms.