Showing papers by "Indian Institute of Technology Guwahati published in 1999"

Closed form expression for mutual partial inductance between two skewed linear current segments

Abstract: A closed form expression is presented for mutual partial inductance between two current segments which may be non-parallel and may be located on different planes. This expression for a pair of skewed lines can be used for computation of the inductances for three dimensional packages and interconnect.

Optical and Thermal Diffusivity Measurement of Ge-Se-Te Glasses by Photoacoustic Technique

Abstract: The composition dependence of optical energy gap $(E_g)$ and thermal diffusivity (\alpha) in three sets of Ge-Se-Te glasses, namely, ${Ge}_x{Se}_{80-x}{Te}_{20}$ 5\leq x \leq40 ${Ge}_x{Se}_{75-x}{Te}_{25}$ 5\leq x \leq40 and ${Ge}_x{Se}_{65-x}{Te}_{35}$ 5\leq x \leq37.5 have been studied using photoacoustic technique. The variation of \alpha with an average coordination number (r) shows a change in the slope at (r) 2:4 and 2.67. ${E_g}$ shows a local maximum at (r) 2:67. The results are discussed on the basis of the topological and chemical threshold exhibited by covalent network glasses. The relative sensitivity of \alpha and ${E_g}$ to these phenomena is discussed.

A VLSI architecture for cellular automata based Reed-Solomon decoder

Abstract: The design of cellular automata (CA)-based SbEC-DbED (single-byte error correcting, double-byte error detecting) code, which is analogous to the extended Reed-Solomon (RS) code, was proposed by D.R. Chowdhury et al. (1994). This code has the same restriction on error correction capability as that of the extended RS code. In this paper, a new scheme has been proposed for pipeline implementation of CA-based tbEC-tbED (t-byte error correcting, t-byte error detecting) codes that are analogous to the conventional RS code. The encoder and decoder of this code can both be implemented in a pipeline with a CA array. The proposed decoder provides a simple, modular and cost-effective design that is ideally suited for VLSI implementation.

Interferometric array illuminator with analysis of nonobservable fringes

Abstract: Interferometric methods for array generation offer various advantages over diffractive methods. Use of polarizing elements in an interferometric array illuminator results in interesting properties in addition to improving the efficiency considerably from low levels. The array pattern appears as nonobservable fringes that can be observed only with a polarizer, and the interferometer is insensitive to one of the tilt components. A thorough analysis of such an interferometric array illuminator is presented in this paper. Several possible applications of such an interferometer in addition to use as an array illuminator are proposed.

Performance of a coherent BPSK receiver in an impulsive noise environment

Abstract: The performance of a digital communication system in the ELF/VLF range operating in situations like a mine environment is strongly affected by atmospheric noise which has an impulsive component on a white Gaussian background. We analyze the bit-error-rate performance of a coherent BPSK receiver subject to such noise.

Molecules in a Thin Bubble Membrane

Abstract: A simple method for generation of a stable bubble membrane from an aqueous solution of sodium dodecyl sulfate (SDS) is reported. The method involves repeated boiling of an aqueous solution of SDS with addition of fresh SDS in the end. An air bubble is blown over a small inverted beaker containing a portion of the solution. With time the bubble loses water and other components and results in a thin membrane. The membrane thus obtained is stable for minutes. Time-dependent UV−vis spectroscopic measurements are used to ascertain the change in thickness of the bubble with time. FTIR spectroscopic measurements have been utilized to follow the change in chemical composition of the bubble. The bubbles containing Rhodamine B and Rhodamine 6G dyes reveal that these dyes remain in the bubbles even if they become very thin. The visible absorption spectra of these dyes indicate that these dyes are possibly in the aqueous layer which may be present in the thin bubble membrane.

Graphical approach to correlations in high‐spin systems

Abstract: We present a graphical technique for generating and indexing spin monomials of high-spin systems. The procedure consists of developing a graph with at most n line segments from each node in a given row to the one immediately lower, where n is the multiplicity of single-particle spin function. The paths lead to monomials with definite M values at each node. This technique has been used to generate and diagonalize the model spin Hamiltonian. ©1999 John Wiley & Sons, Inc. Int J Quant Chem 73: 389–393, 1999

Parallel vertex colouring of interval graphs

Abstract: Evidence is given to suggest that minimally vertex colouring an interval graph may not be in NC1. This is done by showing that 3-colouring a linked list is NC1-reducible to minimally colouring an interval graph. However, it is shown that an interval graph with a known interval representation and an O(1) chromatic number can be minimally coloured in NC1. For the CRCW PRAM model, an o(log n) time, polynomial processors algorithm is obtained for minimally colouring an interval graph with o(log n) chromatic number and a known interval representation. In particular, when the chromatic number is O((log n)1-e), 0

An Environmentally Benign Synthesis of Organic Ammonium Tribromides (OATB) and Bromination of Selected Organic Substrates by Tetrabutylammonium Tribromide (TBATB).

Abstract: Stable crystalline organic ammonium tribromides (OATB), like Me4NBr3, Et4NBr3, Bu4NBr3, cetyltrimethylammonium tribromide, PyHBr3, can be readily synthesised from the reaction of the corresponding bromides with V2O5 and aqueous H2O2. Typically, TBATB, Bu4NBr3, brominates a variety of organic substrates rather easily under mild conditions. An activated aromatic ring is selectively brominated in the presence of an olefinic double bond.