Saibal Chatterjee

Wavelet analysis of optical signal extracted from a non-contact fibre-optic vibration sensor using an extrinsic Fabry–Perot interferometer

Interferometric optical fibre sensors have proved to be many orders of magnitude more sensitive than their electrical counterparts, but they suffer from limitations in signal demodulation caused by phase ambiguity and complex fringe counting when the output phase difference exceeds one fringe period and for multiple fringes. This paper presents a novel signal decoding technique based on the wavelet transform of optical data extracted from a non-contact vibration sensor using an extrinsic Fabry-Perot interferometer (EFPI) implemented using single-mode fibre. The EFPI cavity has been used to generate an optical interference signal between two parallel, highly reflective surfaces separated by a variable distance. Firstly, a few recorded experimental results of the interference fringe formation due to vibration are presented in this paper. Then the wavelet transform is used for decoding the vibration signature for three major purposes of the data analyses, namely elimination of noise from the optical signals collected in real time, identification of the frequency breakdown points of the signal efficiently and automatic counting of the interference fringes. In turn, the wavelet transform is successfully employed to decode the vibration signature from the non-stationary output signal of an EFPI sensor.

C-Field Cosmology in Higher Dimensions

Hoyle and Narlikars

Singularity structure of a self-similar Tolman type model in a higher-dimensional spacetime

C

Time-frequency analysis of multiple fringe and nonsinusoidal signals obtained from a fiber-optic vibration sensor using an extrinsic Fabry-Pe/spl acute/rot interferometer

-field cosmology is extended in the framework of higher dimensional spacetime and a class of exact solutions is obtained. Adjusting the arbitrary constants of integration one can show that our model is amenable to the desirable property of dimensional reduction so that the universe ends up in an effective 4D one.Further with matter creation from the

Surge Modelling of Transformer Using Matlab-Simulink

C

Massive strings in higher-dimensional inhomogeneous spacetime

-field the mass density steadies with time and the usual bigbang singularity is avoided. An alternative mechanism is also suggested which seems to provide matter creation in the 4D spacetime although total matter in the 5D world remains conserved. Quintessence phenomenon and energy conditions are also discussed and it is found that in line with the physical requirements our model admits a solution with a decelerating phase in the early era followed by an accelerated expansion later. Moreover, as the contribution from the

Extended inflation in higher-dimensional spacetime with a Brans-Dicke scalar field

C

Analysis of the effect of electric field due to High Voltage Transmission lines on humans

-field is made negligible a class of our solutions reduces to the previously known higher dimensional models in the framework of Einsteins theory.

Evolution of Kaluza–Klein inhomogeneous model with a cosmological constant

A Tolman-Bondi type inhomogeneous, spherically symmetric metric is obtained in an (n+2)-dimensional spacetime withn≥2. The metric form admits the familiar shell focusing singularity which, depending on the inhomogeneity parameter, may become naked. Moreover, for the particular case of a marginally bound collapsing model one may also obtain strong-curvature singularities, which provides yet another counterexample to the cosmic censorship hypothesis. It is interesting to point out that it is the assumption of self similarity rather than spherical symmetry which determines the nature of the singularity. This, however, extends an earlier observation of Lake and Zannias in four-dimensional spacetime.

A literature review on use of Bewley's lattice diagram

In the case of multiple fringes and complex frequency measurements, the frequency of the output signal changes rapidly when the vibration changes and frequency breakdown takes place at the turning point. For a particular vibration signature containing many frequency components at different time intervals, it is often difficult to trace the direction of the vibration as well as individual frequency peaks. In such cases, advanced signal-processing scheme is necessary to decode the vibration signature. This paper investigates the data interrogation technique for multifrequency and complex signals of surface vibration obtained from an extrinsic Fabry-Pe/spl acute/rot interferometric sensor. In this paper, wavelet transform (WT)-based signal processing methodology has been employed to count of optical fringes with special reference to signals having subfringes. A WT-based tool has also been developed for unambiguous identification of frequency components from a nonsinusoidal vibration. The results of such WT-based analyses are presented, and merits as well as demerits of the proposed methods are discussed.