A5008189598- Solar and Space Plasma Dynamics
- Fluid Dynamics and Thin Films
- X-ray Diffraction in Crystallography
- Crystallization and Solubility Studies
- Photorefractive and Nonlinear Optics
- Solar Radiation and Photovoltaics
- Fractional Differential Equations Solutions
- Nuclear physics research studies
- Geophysics and Gravity Measurements
- Vibration and Dynamic Analysis
- Stellar, planetary, and galactic studies
- Cosmology and Gravitation Theories
- Acoustic Wave Resonator Technologies
- Numerical methods in engineering
- Black Holes and Theoretical Physics
- Composite Structure Analysis and Optimization
- Ionosphere and magnetosphere dynamics
- Solidification and crystal growth phenomena
- Ferroelectric and Piezoelectric Materials
- Bladed Disk Vibration Dynamics
- History and advancements in chemistry
- Nonlinear Photonic Systems
- Solid-state spectroscopy and crystallography
- Relativity and Gravitational Theory
- Advanced Fiber Laser Technologies
Saha Institute of Nuclear Physics
2014-2025
University of Calcutta
1927-2022
Homi Bhabha National Institute
2020
Government of West Bengal
2008-2011
Govt. Dental College & Hospital
2009
Indian Statistical Institute
1990-2003
Indian Association for the Cultivation of Science
1957
Abstract We perform a study of cosmic evolution with an equation state parameter by selecting phenomenological Λ model the form, . This simple proposition explains both linearly expanding and inflationary universes single set equation. note that inflation leads to scaling in parameter, ω(t), hence state. In this approach, one its two parameters has been pin pointed other delineated. It possible show connection between dark energy Higgs–Boson.
In this paper, the data of sunspot areas recorded at US Air Force National Oceanic and Atmospheric Administration during solar Cycles 22 23 (1986 September 1 to 2007 August 31) have been analysed investigate midterm periodicities. Power spectral analysis has performed separately for whole disc, northern southern hemispheres Sun, which provides evidence a multitude quasi-periodic oscillations. During Cycle 22, in high-frequency range, covers rotation periods, shows prominent 27–41 d periods...
A relation between certain irreducible character values of the hyperoctahedral group $B_n$ ($\mathbb{Z}/2\mathbb{Z} \wr S_n$) and symmetric $S_{2n}$ was proved by F. L\"ubeck D. Prasad in 2021. Their proof is algebraic nature uses Lie theory. Using combinatorial methods, R. Adin Y. Roichman a similar $G\wr S_n$ $S_{rn}$, where $G$ an abelian order $r$ (generalizing result L\"ubeck-Prasad). their result, we prove yet another $r$.
In this paper we study the isotropic cases of static charged fluid spheres in general relativity. For purpose consider two different specialization and under these solve Einstein-Maxwell field equations coordinates. The analytical solutions thus obtained are matched to exterior Reissner-Nordstr\"om which concern with values for metric coefficients $e^{\nu}$ $e^{\mu}$. We derive pressure, density, pressure-to-density ratio at centre sphere boundary $R$ star. Our conclusion is that provide a...
Ferroelectric materials such as lithium niobate and tantalate show a non-linear hysteresis behaviour, which may be explained by dynamical system analysis. The behaviour of these ferroelectrics is usually domains domain wall movements. So, the spatial variation was studied previously in order to see its effect on width context Landau–Ginzburg functional. In present work, both temporal variations polarization are considered, using Euler–Lagrange equation motion, Klein–Gordon derived taking...
Gradual formation of a thin liquid film on hot/cold rotating disc under the action thermocapillary force is studied analytically. It found that acting free surface enhances thinning rate for cooling disc.
The data of energetic solar electron fluences measured in two ranges energy values (E > 0.6 and 2 MeV) by the IMP-8 spacecraft NASA, cycles 21, 22 a major part current cycle 23, have been analysed for first time three different methods to detect periodicities accurately. Power spectral analysis flux shows periodicity ∼152 d ∼330 ∼604 ∼176 23. respective are found be independent as other kinds activity reported earlier researchers, thus indicating intimate relationship emission with activity.
A model of a ferroelectric crystal in terms one-dimensional array slab domains is treated theoretically for the dynamics ``array domains.'' Two approaches are considered. In first, system within continuum limit which space and time evolution polarization described by nonlinear Klein-Gordon equation. multiple-time-scale analysis used to determine linear parts frequencies extended modes oscillation array. An application also made study these presence impurities inhomogeneous materials such as...
ABSTRACT The sunspot cycle waxes and wanes over a period of about 11 years modulates ‘space weather’. Therefore, predicting the maximum amplitude solar is an important goal for both physics space weather. It clear nowadays that cyclic variations Sun are non-linear processes, thus above-mentioned difficult to reach with accuracy, albeit several methods currently exist forecast long-term short-term variations. Solar 25 has recently started knowing strength timing this in advance essential. In...
The Kodaikanal Observatory has made synoptic observations of the Sun in white light since 1904, and these images are sketched on Stonyhurst grids called sun charts. These continuous hand-drawn data sets used for long-term studies Sun. This article investigates temporal periodic variations monthly hemispheric sunspot number group area 1905--2016, covering solar cycles 14 to 24. We find that different each hemisphere peak at times cycle opposite hemisphere. For both sets, Cycle 19 shows...
The nonlinear hysteresis behavior in ferroelectric materials, such as lithium tantalate and niobate, may be explained by dynamical systems analysis. In a previous work, the polarization “domain wall width” was studied terms of only spatial variation eventually critical values were determined to derive stability zone context Landau-Ginzburg free energy functional. present temporal dynamics domains themselves are considered taking time through Euler-Lagrange equation motion, which gives rise...