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The paper concentrates on the study of reflection characteristics of acoustodiffusive waves from the surface of a semiconductor halfspace which is subjected to stress free, isoconcentrated and stress free, impermeable conditions. The effect of life and relaxation times of charge carriers (electron or holes) fields on the wave characteristics is also investigated. The amplitude ratios (reflection coefficients) of reflected waves to that of incident wave are obtained for incident quasilongitudinal (qP), quasitransverse (qSV), and electron-(N) and hole (P) wave cases. The special cases of normal and grazing incidence are also derived and discussed. Finally, the numerical computations of reflection coefficients are carried out with the help of Gauss elimination method by using MATLAB programming software. The computer simulated results in respect of stress free conditions have been plotted graphically for silicon (Si) and presented in tabular form in case of germanium (Ge) semiconductors. The study may be useful in semiconductors and surface acoustic wave devices in addition to geophysical applications.

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The mechanical properties of the particulate reinforced composites are profoundly affected by two significant factors, fraction of reinforcement in the matrix and the distribution of the reinforced particles in the matrix. In this paper, a novel approach is adopted where a newly developed distribution index and area fraction of the composites are quantitatively determined through microstructural image analysis method, and the process parameters are optimised for maximum area fraction and minimum distribution index. The distribution index (Dindex) is calculated by estimating the free-path spacing within particles. The stir casting process parameters (stirrer rpm, time of stirring, furnace temperature and preheat temperatures) are optimised by Box-Behnken design of response surface methodology. The quantitatively assessed responses provide an authentic base for optimisation of process parameters. The experimental responses corresponding to the optimised parameters are within the range of the responses estimated by the confirmation test of optimisation with a 95 % confidence level.

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