A Fourier transform speckle method to determine the change in angle of illumination

It is analytically shown that the position of the Fourier transform of the speckle pattern produced by a coherently illuminated, diffusely reflecting surface depends upon its angle of illumination. A method is proposed to measure small changes in this angle by doubly exposing the photographic plate with the original and laterally displaced Fourier transforms of the object speckle. The method is well suited for accurate measurements of the wedge angle and tilt of optical surfaces and to determine variations in refractive index or temperature of axially symmetric phase objects.     

Effect of Lead Time on Inventory — A Working Result

A relationship between standard deviation of demand during lead time (normally distributed) and economic order quantity on the basis of (Q, R) inventory model with variable lead time has been developed.     

Reliability Education in India?Present and Future

This paper surveys the present status and efforts in formal and informal reliability education in India. Survey of important research activities as indicated by the published research papers in this Transactions for the last five years is also included. A three phase programme for future training in reliability for developing countries like India is suggested. Phase one consists of immediate introduction of an elective course for all disciplines of engineering at undergraduate level which should be gradually converted into a compulsory course. Phase two consists of introducing a specialized 2-year postgraduate programe in reliability engineering. Brief course details for both these phases are given. Phase three is the establishment of a National Reliability Research Centre to coordinate, direct, and advance research activities.     

Thermal degradation of poly(vinyl chloride). I. Structural effects in the initiation and decomposition chain lengths

Four poly(vinyl chloride) samples containing different structural irregularities were thermally decomposed. The rates of HCl evolution were compared to the rates of radical generation in the samples. Orders of stabilities related to the structural entities for the initiation of decomposition and for the chain lengths of HCl evolution were established.     

Angular forces in the lattice dynamics of diamond crystal lattices

The lattice dynamics of the diamond lattice has been investigated using a model in which the interatomic forces include, in addition to central forces, the angular forces of the type employed by de Launay and Clark, Gazis and Wallis. The 2 models have been applied to silicon and germanium to investigate the phonon dispersion curves in the three symmetry directions of the Brillioun zone. The results are found to be qualitatively in good agreement with experiments.     

Effect of Receiver Bandwidth on Waveforms and Time Characteristics of Atmospheric Radio Noise Bursts

Several investigators have presented the results of their experimental investigations and theoretical expectations on the effect of receiver bandwidth on the time characteristics and waveforms of atmospheric radio noise bursts. The experimental and theoretical findings do not appear to agree with each other. This communication offers a possible explanation for this "discrepancy" with support from experimental evidence, drawn from a large number of references included in this communication.     

On profit evaluation in a two-unit maintained redundant system

A two-unit redundant system is considered and analytic expression for total expected profit earned in a given time is obtained after writing basic cost equations governing the behaviour of the system.A procedure is suggested to obtain optimal failure and repair rates so that expected steady state profit is maximum.     

Evidence of incipient bond-stretching isomerism in Sr2.04(1)Ca0.96(1)Sn5 from variable-temperature structural studies

The title compound was found to crystallize in the Pu3Pd5 structure type (SG Cmcm) with cell dimensions of a = 10.5179(9) A, b = 8.4789(8) A, and c = 10.7623(10) A. The structure consists of isolated Sn5(6-) square-pyramidal units surrounded by cations that seem to play a crucial role in stabilizing the Zintl polyanions. The square pyramids contract at low temperatures (100 K) leading to the shortening of the basal intracluster Sn-Sn bond (2.74 A), while the intercluster bonds become very large, indicating features of bond stretching isomerism as is known for Ba3Ge4. A study of different crystals shows a slight variation in the lattice parameters, suggesting the presence of a definite phase width which was substantiated by the successful synthesis of monophasic samples of Sr(3-x)CaxSn5 (0.5 相似文献