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Diffusive and stochastic analysis of Lokta-Volterra model with bifurcation
C.V. Pavan Kumar,G. Ranjith Kumar,Kalyan Das,K. Shiva Reddy,Md. Haider Ali Biswas 한국전산응용수학회 2023 Journal of applied mathematics & informatics Vol.41 No.1
The paper presents a critical analysis of selected topics related to the modeling of interacting species in which prey has nonlinear reproduction, which is in competition with predator. The mathematical model's stochastic stability is investigated. The method of designing appropriate Lyapunov functions is used to identify permanence conditions among the parameters of the model and conditions for the structure to no longer be extinct. The system's two-dimensional diffusive stability is regarded and studied. The system experiences the process of saddle-node bifurcation by varying the death rate of predator parameter. Further effects of parameters that undergo inherent oscillations are numerically investigated, revealing that as the intensity of predation parameter b is increased, the device encounters non-periodic and damped oscillations.
Sujatha Pavan Narayanam,Amit Kumar,Usha Pujala,Subramanian V.,Srinivas C.V.,Venkatesan R.,Athmalingam S.,Venkatraman B. 한국원자력학회 2022 Nuclear Engineering and Technology Vol.54 No.6
In the unlikely event of core disruptive accident in sodium cooled fast reactors, the reactor containmentbuilding would be bottled up with sodium and fission product aerosols. The behavior of these aerosols iscrucial to estimate the in-containment source term as a part of nuclear reactor safety analysis. In thiswork, the evolution of sodium aerosol characteristics (mass concentration and size) is simulated usingHAARM-S code. The code is based on the method of moments to solve the integro-differential equation. The code is updated to FORTRAN-77 and run in Microsoft FORTRAN PowerStation 4.0 (on Desktop). Thesodium aerosol characteristics simulated by HAARM-S code are compared with the measured values atAerosol Test Facility. The maximum deviation between measured and simulated mass concentrations is30% at initial period (up to 60 min) and around 50% in the later period. In addition, the influence ofhumidity on aerosol size growth for two different aerosol mass concentrations is studied. The measuredand simulated growth factors of aerosol size (ratio of saturated size to initial size) are found to bematched at reasonable extent. Since sodium is highly reactive with atmospheric constituents, the aerosolgrowth factor depends on the hygroscopic growth, chemical transformation and density variations besides coagulation. Further, there is a scope for the improvement of the code to estimate the aerosoldynamics in confined environment
Kim, H.J.,Kim, J.H.,Pavan Kumar, CH.S.S.,Punnoose, D.,Kim, S.K.,Gopi, C.V.V.M.,Srinivasa Rao, S. Elsevier Sequoia 2015 Journal of Electroanalytical Chemistry Vol.739 No.-
In this paper, highly efficient nano peas like structure CuS film has been successfully employed in quantum dot sensitized solar cells (QDSSCs) for its highest catalytic activity at minimal cost. The CuS thin film electrode was deposited on fluorine-doped tin oxide (FTO) substrate by chemical bath deposition technique using urea at low deposition temperatures. This electrode elevated the short circuit current and fill factor in comparison to the frequently used Pt electrode. Moreover, electrochemical measurement data disclosed higher electrocatalytic activity toward polysulfide reduction. The CuS film exhibited an average particle size of 180-270nm and film thickness of 825nm. It also revealed superior J<SUB>sc</SUB> (13.87mA/cm<SUP>2</SUP>) and conversion efficiency of 4.01% which is remarkably higher than that of the Pt-based cell (1.07%). In addition, stability test conducted for both CuS and Pt-based cells for about 900min at working conditions affirmed that the long-term stability of the CuS film decreased by 16.66% (4.02-3.35%), while that of the Pt based cell got elevated by 24.29% until 700min, and consequently diminished by 8.27% from 700 to 900min.