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Mishra V.D.,Snow and Avalanche Study Establishment SASE | Sharma J.K.,Rayat Institute of Engineering and Information Technology | Khanna R.,Thapar University
Annals of Glaciology | Year: 2010

The topographic effects of differential terrain illumination in optical satellite imagery of rugged mountainous regions have serious consequences for qualitative and quantitative analysis for various snow applications. Therefore, effective removal or minimization of topographic effects is necessary in satellite image data of mountainous regions. Different methods for topographic corrections, including C-correction, Minnaert corrections (including slope) and slope-matching method, are analysed in the context of snow reflectance. Combination of dark-object subtraction models DOS1 and DOS3 is used for image-based atmospheric corrections while considering the effect of Rayleigh scattering on the transmissivity in different spectral bands of AWiFS and MODIS image data. The performance of different models is evaluated using (1) visual analysis, (2) change in snow reflectance on sunny and shady slopes after the corrections, (3) validation with in situ observations and (4) graphical analysis. The results show that the slope-matching technique could eliminate most of the shadowing effects in Himalayan rugged terrain and correctly estimate snow reflectance from AWiFS and MODIS imagery. The validation of results with in situ observations for both types of imagery suggests that all other methods significantly underestimate reflectance values after the corrections.


Verma R.,Rayat Institute of Engineering and Information Technology
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2013

The phenomenology of the most general lepton mass matrices obtained through weak basis transformations has been discussed. Using a hierarchical parametrization of these mass matrices, the exact relations for lepton mixing angles have been obtained assuming normal neutrino mass hierarchy and natural structures of lepton mass matrices. The recent three neutrino oscillation data together with the condition of naturalness on the Dirac lepton mass matrices provide a lower bound on the lightest neutrino mass of mv1>3 meV along with a nonvanishing Dirac CP violating phase. © 2013 American Physical Society.


Verma R.,Rayat Institute of Engineering and Information Technology
Journal of Physics G: Nuclear and Particle Physics | Year: 2013

The phenomenology of the most general quark mass matrices with a minimum of three texture zeros obtained through weak basis (WB) transformations has been discussed within the framework of the standard model. The relationship between the textures, naturalness and WB transformations has also been studied. Adopting a 'hierarchical' parameterization for the quark mass matrix, we have detailed exact relations for the various elements of the quark mixing matrix along with the CP asymmetry angle β, illustrating the explicit relationship between the observed hierarchies among the WB quark mass matrices and the quark mixing matrix. Besides exploring the complete parameter space available to the (M q)11, (q = u, d) elements in these mass matrices, their implications for quark mixing data and CP violation asymmetries have also been explored. © 2013 IOP Publishing Ltd.


Verma R.,Rayat Institute of Engineering and Information Technology | Ahuja G.,Panjab University | Mahajan N.,Panjab University | Randhawa M.,Panjab University | Gupta M.,Panjab University
Journal of Physics G: Nuclear and Particle Physics | Year: 2010

We have attempted to extend the parameter space of the elements of the texture four-zero Hermitian quark mass matrices, to include the case of 'weak hierarchy' amongst them along with the usually considered 'strong hierarchy' case. This has been carried out by giving wide variation to the hierarchy defining parameters DU and DD, having implications for the structural features of the mass matrices. We find that not only are the weakly hierarchical mass matrices able to reproduce the strongly hierarchical mixing angles but also both the phases, having their origin in the mass matrices, have to be non-zero to achieve compatibility of these matrices with recent quark mixing data. Further noting the difference between the exclusive and inclusive values of Vub, we have carried out separate analyses corresponding to these. © 2010 IOP Publishing Ltd.


Verma R.,Rayat Institute of Engineering and Information Technology
International Journal of Modern Physics A | Year: 2010

A detailed investigation of all possible textures of Fritzsch-like and non-Fritzsch-like, 144 for texture 6 zero and 432 for texture 5 zero mass matrices, have been carried out to ascertain their compatibility with the existing quark mixing data. It seems that all the texture 6 zero possibilities are completely ruled out whereas in the case of texture 5 zero mass matrices the only viable possibility looks to be that of Fritzsch-like. © 2010 World Scientific Publishing Company.

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