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Manas Kumar Roy

Publications and source records attributed to Manas Kumar Roy.

3 recordsLinked to original sources

Dynamics of Chemical Orders in Formation of Striped Patterns in Metamorphic Rocks

The striped patterns in rocks, characterized by thin dark bands and thick light bands, are a result of the natural processes that have shaped the rocks through in situ metamorphism. Notably, the dark and light bands are composed of similar minerals, with the dark bands containing additional trapped materials such as fluid pockets or extra mineral grains. Here we employed the Gray-Scott Reaction Diffusion model to investigate the interaction between two sets of virtual chemicals, denoted as 'u' and 'v'. The differing diffusion and reaction rates of 'u' and 'v' chemical orders lead to the formation of 180 degree out-of-phase chemical domains, resulting in striped patterns. Utilizing the Gray-Scott model in this manner, we gain valuable insights into the early microscopic stages of these geologically significant striped patterns in metamorphic rocks.

cond-mat.mtrl-sci

Formation of vortex and antivortex polarization states in ferroelectric films

An effort based on the kinetic model allowed by Landau-Ginzburg-Devonshire theory is presented here. The formation of vortex, antivortex states in ferroelectric films are reported and theoretically explained. Phase transition in toroidal moment is observed. Vortex-antivortex-vortex (V-AV-V) triplet is generated by applying inhomogeneous transverse static localized fields in x-y plane. A specific boundary condition is used to keep the spirit of vortex state i.e. the net polarization across the boundary is always zero. %This is neither a periodic nor an open circuit electric boundary condition.

cond-mat.mtrl-sci

Sound beam through a circular aperture and the far-field nonparaxial regime

Propagation of sound beam diffracted from a circular aperture in far-field region has been studied in this paper by the method of angular spectrum representation and stationary phase method. This nonparaxial theory is useful when beam angle is not very small and the wavelength $λ$ is comparable to aperture diameter $a$ unlike the situation in paraxial approximation. Here we have studied two cases, one for a Gaussian source and other for a plane piston source.

physics.class-ph