Informatics Publishing Limited

K. Kavya ¹, G. Sateesh Kumar ¹, D. V. L. N. Sastry ¹

Affiliations
1 Department of E.C.E. Aditya Institute of Technology and Management, Tekkali, Andhra Pradesh, IN

Abstract

The digital data on the internet is not secure, because the digital data is easily modified and copied. So that one system is need to prevent this unauthorized access of digital data for owner authentication. There are many systems available in the literature and one popular system is image signature. The DWT-based image signature algorithms have multi-resolution description characteristics are achieving imperceptibility. The SVD based image signature algorithms add the signature information to the singular values of the diagonal matrix achieving robustness requirements. An approach to a robust multiple-image signature method based on Discrete Wavelet Transform and Singular Value Decomposition in YCbCr color space is proposed to get good imperceptibility and robustness. The cover image is a signature with multiple images to meet better security from unauthorized persons. The proposed algorithm provides good robustness against various attacks.

Keywords

DWT, Imperceptibility, SVD, Robustness, Watermark Embedding and Watermark Extraction.

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U. K. Pandey ¹, D. V. L. N. Sastry ¹, B. K. Pandey ¹, Madhuparna Roy ², T. P. S. Rawat ², Rajeeva Ranjan ³, V. K. Shrivastava ³

Affiliations
1 Atomic Mineral Directorate for Exploration and Research, Geochronology Lab., Begumpet, Hyderabad - 500 016, IN
2 Atomic Mineral Directorate for Exploration and Research, Northern region, New Delhi - 110 066, IN
3 Atomic Mineral Directorate for Exploration and Research, Central Region, Nagpur - 440 001, IN

Abstract

The Dargawan gabbros intrusive into the Moli Subgroup of Bijawar Group, yielded Rb-Sr whole rock isochron age of 1967 ± 140 Ma. Based on the oldest age from overlying Lower Vindhyan (1.6Ga) and the underlying youngest basement ages (2.2 Ga), the time range of Bijawar sedimentation may be assigned as 2.1-1.6 Ga (Paleoproterozoic). Sm-Nd Model ages (T_DM), obtained, for Dargawan gabbros, is c. 2876 - 3145 Ma. High initial ⁸⁷Sr/ ⁸⁶Sr ratio of 0.70451 (higher than the contemporary mantle) and negative ε_Ndi (at 1.9 Ga) value of -1.5 to -4.5, indicate assimilation of Archaean lower crustal component by the enriched mantle source magma at the time of gabbroic intrusion. The dolerite, from Damdama area, which is intrusive into the basement and overlying sediments of Chandrapur Group in the central Indian craton, yielded Rb-Sr internal isochron age of 1641 ± 120 Ma. The high initial ⁸⁷Sr/⁸⁶Sr ratio of 0.7098 and ε^Ndi value of -3.5 to -3.7 (at 1.6 Ga) is due to contamination of the mantle source magma with the overlying sediments. These dolerites have younger Sm-Nd Model ages (T_DM) than Dargawan gabbros as c. 2462 - 2675 Ma, which is similar to the age of the Sambalpur granite, from which probably sediments to this part of Chattisgarh basin are derived. Hence mixing of sediments with the Damdama dyke during its emplacement, gives rise to high initial ⁸⁷Sr/⁸⁶Sr and low initial ¹⁴³Nd/¹⁴⁴ ratios for these dykes. The c. 1600 Ma age indicates minimum age of onset of the sedimentation in the Chandrapur Group of Chattisgarh basin. Both the above mafic intrusions might have taken place in an intracratonic rift related (anorogenic) tectonic setting. This study is the first reliable age report on the onset of sedimentation in the Chandrapur Group. The total minimum time span of Chandrapur and Raipur Group may be 1.6 Ga to 1.0 Ga (Mesoproterozoic). The unconformably underlying Shingora Group of rocks of Chhattisgarh Supergroup thus indicates Paleoproterozoic age (older than 1.6 Ga). Most part of the recently classified Chattisgarh Supergroup and Bijawar- Vindhyan sequence are of Mesoproterozoic-Paleoproterozoic age and not of Neoproterozoic-Mesoproterozoic age as considered earlier. Petrographic study of basic dykes from Damdama area (eastern margin of Chattisgarh Supergroup) indicated presence of primary uranium mineral brannerite associated with goethite. This is the evidence of mafic intrusive providing geotherm and helping in scavenging the uranium from the surrounding and later alterations causing remobilisation and reconcentration of pre-existing uranium in host rocks as well as in mafic dyke itself otherwise mafic rocks are poor source of uranium and can not have primary uranium minerals initially. It can be concluded that mafic dykes have role in uranium mineralisation although indirectly.

Keywords

Geochronology, Age of Sedimentation, Uranium Mineralisation, Northern and Central Indian Cratons.

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