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Showing papers by "K. Ramesh published in 1987"


Proceedings ArticleDOI
17 Feb 1987
TL;DR: In this article, a survey is given of the direct and indirect methods used to determine the three characteristic parameters and then a new indirect method to determine these parameters is presented, which is verified experimentally and compared with theoretically determined characteristic parameters using Jones calculus.
Abstract: In the process of determining the complete state of stress at a general point in a three dimensional photoelastic model (in a non-destructive or a semi-destructive manner), the concept of optically equivalent model plays a very important role. There are three parameters that define an optically equivalent model and these are termed as characteristic parameters. In this paper, first a survey is given of the direct and indirect methods used to determine the three characteristic parameters and then a new indirect method to deter-mine these parameters is presented. An algorithm has also been developed to determine the characteristic parameters unambiguously by the new method. The new method is verified experimentally and compared with theoretically determined characteristic parameters using Jones calculus.

3 citations


Journal ArticleDOI
TL;DR: In this article, the authors studied electron trapping due to mobile sodium ions in silicon dioxide near the Si-SiO2 interface using MOS capacitors and found that the number of trapped electrons, as measured by shifts in flatband voltage of high frequency C-V curves, is proportional to the sodium ion density.
Abstract: We have studied electron trapping due to mobile sodium ions in silicon dioxide near the Si-SiO2 interface using MOS capacitors. After doing a bias-temperature stress, hot electrons were injected into SiO2 by avalanche injection. The number of trapped electrons, as measured by shifts in flat-band voltage of high frequency C-V curves, is proportional to the sodium ion density. The depth of these electron traps was found by a thermal detrapping experiment to be about 1.2 eV. A possible model for the origin of the mobile sodium-related electron trap is presented.