Browsing by Author "Kumar, J"

Now showing 1 - 6 of 6
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    Asymmetric double-image encryption using twin decomposition in fractional Hartley domain
    (2022) Kumar, J; Singh, P; Yadav, AK
    Twin decomposition, consisting of equal and random modulus decompositions, not only makes a cryptosystem asymmetric but also resists special attack. A new double-image asymmetric crypto system using twin decomposition in fractional Hartley domain is proposed. An input grayscale image, bonded with another grayscale image as its phase mask, is transformed via fractional Hartley transform. Equal modulus decomposition is applied on the resulting image, giving us two inter mediate images. One of them is subjected to another fractional Hartley transform followed by ran dom modulus decomposition, whereas the other serves as the first private key. The application of random modulus decomposition also results in two images: encrypted image and the second private key. During the process of decryption, firstly the encrypted image is combined with second private key and thereafter it is subjected to inverse fractional Hartley transform. The resulting image is then combined with the first private key, and followed by another inverse fractional Hartley trans form, thus recovering the two original images. The proposed cryptosystem is validated for pairs of grayscale images.
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    A comparative study of wormhole geometries under two different modified gravity formalism
    (2024-03) Kiroriwal, S; Kumar, J; Maurya, S.K.; Chaudhary, S
    In the current article, we discuss the wormhole geometries in two different gravity theories, namely F(Q, T) gravity and F(R, T) gravity. In these theories, Q is called a non-metricity scalar, R stands for the Ricci scalar, and T denotes the trace of the energy–momentum tensor (EMT). The main goal of this study is to comprehensively compare the properties of wormhole solutions within these two modi fied gravity frameworks by taking a particular shape function. The conducted analysis shows that the energy density is con sistently positive for wormhole models in both gravity theo ries, while the radial pressure is positive for F(Q, T) gravity and negative in F(R, T) gravity. Furthermore, the tangential pressure shows reverse behavior in comparison to the radial pressure. By using the Tolman-Oppenheimer-Volkov (TOV) equation, the equilibrium aspect is also described, which indi cates that hydrostatic force dominates anisotropic force in the case of F(Q, T) gravity theory, while the reverse situation occurs in F(R, T) gravity, i.e., anisotropic force dominates hydrostatic force. Moreover, using the concept of the exotic ity parameter, we observed the presence of exotic matter at or near the throat in the case of F(Q, T) gravity while mat ter distribution is exotic near the throat but normal matter far from the throat in F(R, T) gravity case. In conclusion, precise wormhole models can be created with a potential NEC and DEC violation at the throat of both wormholes while having a positive energy density, i.e., ρ > 0.
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    MEASURING URBAN EXPANSION AND LAND USE/LAND COVER CHANGES USING REMOTE SENSING AND LANDSCAPE METRICS: A CASE OF REWARI CITY, INDIA
    (2024-05) Kanav, A; Kumar, S; Sharma, R; Kumar, J
    The industrial and economic development has initiated the rapid growth of small and medium-sized towns in India. Rewari City, a part of the National Capital Region of India, is undergoing rapid urban expansion. This study analyzes the process of urban expansion in Rewari city, its effect on land use & land cover dynamics and landscape spatial patterns. The methodology of the study is reliant on open-source Landsat satellite data, GIS-based unsupervised classification, and spatial metrics analysis. The city expansion has been analyzed for a period of 31 years, from 1989 to 2020, and population growth has been studied since 1901. Within the study period, built-up area increased by 704%, with an annual expansion rate of 12.8 %. The other land cover classes, such as agriculture land, vegetation, barren land, and water bodies shrank in size over the years. Between 1989 and 2020, 69.4 % of the increase in built up area came at the expense of vegetation and agricultural land. It was also found that per capita land consumption rate increased significantly from 0.0024 to 0.0084, hinting towards dispersed and low-density development. Built-up land had a growth rate nearly 5 times higher than population, indicating urban sprawl. An evaluation of different landscape metrics revealed that the landscape of Rewari has lost land use diversity. The findings of this study offer information about the present state of urban growth. It also serves as a valuable resource for formulating comprehensive planning and development policies, ensuring the promotion of sustainable urban development.
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    Relativistic modeling of stellar objects in a Schwarzschild’s coordinates with embedded class one spacetime
    (2023-06) Prasad, AK; Kumar, M; Kumar, J
    In this study, we investigate a new relativistic anisotropic Einstein field equations solution for compact stars under embedding class 1 conditions. In order to do this, we apply the Karmarkar condition and the embedding class one technique. By taking Buchdahl type metric poten tial grr into consideration, the precise analytical solution has been investigated. We have studied physical characteristics of various compactstarusingthisanalytical solution. Central singularities are absent from the solution. We have explored thermodynamic observables inside the stellar models, such as radial and tangential pressures, matter density, anisotropic factor, energy conditions, TOV, red-shift, and the speed of sound, etc., after establishing this space-time geometry for the stellar models. From the graphical representation of vari ousphysicalcharacteristics,itisdemonstratedthatourmodel meets all the specification for ultra-high density compact bodies.
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    Relativistic modeling of stellar objects in a Schwarzschild’s coordinates with embedded class one spacetime
    (2023-06) Prasad, A; Kumar, M; Kumar, J
    In this study, we investigate a new relativistic anisotropic Einstein field equations solution for compact stars under embedding class 1 conditions. In order to do this, we apply the Karmarkar condition and the embedding class one technique. By taking Buchdahl type metric poten tial grr into consideration, the precise analytical solution has been investigated. We have studied physical characteristics of various compact star using this analytical solution. Central singularities are absent from the solution. We have explored thermodynamic observables inside the stellar models, such as radial and tangential pressures, matter density, anisotropic factor, energy conditions, TOV, red-shift, and the speed of sound, etc., after establishing this space-time geometry for the stellar models. From the graphical representation of vari ous physical characteristics, it is demonstrated that our model meets all the specification for ultra-high density compact bodies.
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    Remediation of toluidine blue O dye from aqueous solution using surface functionalized magnetite nanoparticles
    (2024) Jangra, A; Kumar, R; Singh, D; Kumar, H; Kumar, J; Kumar, P; Kumar, S
    In the current study, tannic acid-functionalized iron oxide nanoparticles have been synthesized using a cost-effective co-pre cipitation method and subsequently characterized using various instrumentation techniques such as Fourier transform infrared spectroscopy, X-ray diffractometer, field emission scanning electron microscopy, and thermal gravimetric analysis. Further, these surface-modified magnetite nanoparticles have been used for the adsorption of toluidine dye from an aqueous solution. The adsorption process was accompanied using batch procedure, and influences of several factors such as adsorbent dose, contact time, pH, temperature, and initial concentration of adsorbate were inspected concurrently. The maximum adsorp tion capacity of tannic acid-functionalized magnetite nanoparticles was found to be 50.68 mg/g. The adsorption process was observed to follow the Temkin isotherm model, whereas the kinetic study was well described by pseudo-second order. The thermodynamic study revealed the adsorption process to be endothermic and spontaneous in nature with a high degree of freedom between adsorbent and adsorbate. Therefore, the study indicated that the tannic acid-functionalized magnetite nano particles have promising adsorption capability and can be used as an excellent adsorbent for the removal of toluidine blue O dye from the aqueous solution.