Pramana最新文献

This article carried out an investigation on the entropy optimisation and effects of Hall current followed by other key parameters on an electrically conducting rotational viscous nanofluid containing micro-organisms combined with different Biot numbers at the boundary layers. The governing mathematical model is converted into nonlinear coupled ordinary differential equations followed by boundary conditions using similarity transformation. Further, the obtained equations are numerically solved by the bivariate spectral quasi-linearisation method (BSQLM). The effect of key parameters has been analysed graphically. A decrease in the flow rate and an increase in both temperature and solute profiles are perceived, corresponding to thermal and solutal Biot numbers, respectively. Moreover, favourable outcomes are also observed for the generation of entropy for different Reynolds and Brinkman numbers.

In this article, we conduct nonlinear time series analysis and utilise machine learning (ML) techniques for predicting and forecasting daily sunspot data sets. Additionally, we review available time series and ML techniques to provide a comprehensive overview. For time series analysis, the variations in the persistence of sunspot data sets were confirmed through Hurst exponent with various time lengths. Moreover, the fast Fourier transform was performed. For the ML approach, prediction and forecasting of sunspot data sets are performed with various simple ML algorithms. Recurrent neural networks (RNN), long–short time memories (LSTM) and gated recurrent unit (GRU) algorithms were used for the prediction. A discussion of the significant outcomes of the sunspot predictions made using the aforementioned algorithms is presented. With the use of these sunspot data sets, several statistical metrics, including R-squared, mean average error (MAE), etc., are examined. Further, the sunspot data forecast was done for more than eight solar cycles with the help of different forecasting algorithms (e.g., neural basis expansion analysis for time series (N-BEATS), neural hierarchical interpolation for the time series (NHITS), etc.). A summary of the sunspot predictions using several ML techniques in an effort to determine the most effective methodology is discussed.

The nonlinear corrections to the gluon distribution are found to play an increasingly important role compared to the singlet distribution with respect to the saturation exponent at small x. The nonlinear corrections for the singlet and gluon distributions are important in a limited range of (Q^2) and are independent of the upward and downward evolutions. This allows us to single out the region where the nonlinear corrections may provide evidence for recombination. We numerically study the nonlinear terms for nuclear singlet and gluon distributions and quantify the impact of gluon recombination in a wide range of (Q^2). This analysis indicates that the nonlinear effects are most pronounced for heavy nuclei and are sizable at (2 lesssim Q^2lesssim 20~textrm{GeV}^2) for light and heavy nuclei.

The collision of a pair of shock waves in a plasma medium is described by the coupled Ramani equation,

This equation is a nonlinear evolution equation, and its travelling-wave solution in the exact form provides insight into its various physical phenomena. When evaluating the accuracy of more advanced versions of these equations when solved numerically, these precise analytical answers serve as a basis for further investigation. The improved (({G'}/{G}))-expansion approach is used to discuss travelling-wave solutions of the coupled Ramani problem in this study. In terms of rational, trigonometric and hyperboloic functions, exact solutions are found. Studying the physically important soliton solutions of the coupled Ramani problem is made possible by this analytical treatment of the equation.

In this paper, the moderately long-time behaviour of the correlation functions for two charged coupled harmonic oscillators connected to a common heat bath are analysed in the presence of a magnetic field via the quantum Langevin dynamics. Interestingly, it is seen that long-time correlation functions at (Trightarrow 0) exhibit a power-law decay with coefficients of the power laws being completely different for the two masses, affecting the overall dynamics of the coupled system. The effect of the bath-induced force on mass (m_1) mediated by the interaction of (m_2) with the common heat bath is studied and the results are highlighted in the presence of an external magnetic field. It is shown that the effect of cyclotron frequency increases the magnitudes of correlation functions at an instant of time by lowering the rate of temporal decay in the presence of a uniform magnetic field. The results in the absence of magnetic field are also presented, which are extremely important for investigating the movements of atoms in a protein molecule at low temperature.

Heavy-ion collision simulations in intermediate energy regime using isospin quantum molecular dynamics model have been proposed as a novel means to glean information about the high density behaviour of nuclear matter. Herein, the influence of modelling the pressure gradient by changing stiffness parameter and isospin asymmetry on the dynamics of charged particles have been investigated. In this research, three different values of stiffness parameter, (gamma =) 0.66 (soft), 1 (stiff) and 2 (super-stiff), to tune the anisotropic transverse pressure gradients have been considered to explore the influence of density-dependent symmetry energy

on the electromagnetic field and energy density evolution. Stiffer symmetry energy (( gamma =) 2) leads to larger pressure gradient than softer symmetry energy (( gamma =) 0.66) that drives stronger expansion resulting in higher intensity of ((eB_{y}(0, 0, 0))_{textrm{max}}) and (langle | vec {E}cdot vec {B}|rangle _{textrm{max}}). The correlation of eccentricity, nuclear stopping, centrality with the electromagnetic field and energy density have been established for different stiffness parameters. To deepen this study, the influence of isospin asymmetry (N/Z) on the time evolution of electromagnetic field has also been explored.

For incompressible fluids, no discernible differences exist between microscale and macroscale flows. However, surface roughness has emerged as a significant factor influencing mass transport phenomena at the microscale due to the substantial increase in the surface-to-volume ratio. In this work, we establish a model of a cross-shaped micromixer with structural roughness elements using the finite-element software Comsol. A comprehensive study is conducted to assess the effects of roughness parameters on mixing performance. Our findings indicate that the roughness height can improve mixing quality compared to smooth channels, which is attributed to the extrusion of roughness on the working medium at a low Reynolds number (Re) of 1 and the increase of lateral velocity at high Re = 50. When the roughness height is increased from 2 to 20 μm, the maximum mixing quality is increased by about 7.4 and 32.8% at Re = 1 and 50, respectively. Furthermore, narrowing the roughness pitch enhances the perturbation frequency of microfluidics, thus facilitating the mixing process. When the pitch is reduced from 200 to 20 μm, the maximum mixing quality at Re = 1 and 50 increases by about 1.9 and 13.8%, respectively. This paper provides new insights into the influence of microrough structures on mixing.

Quantum tunnelling plays a role in some physical phenomena, such as electron emission from metals in the presence of an external electric field, alpha radiation from the nucleus, etc. The phenomenon of neutron emission from the surface of palladium hydride metal when palladium and platinum electrodes are electrolysed in water or heavy-water electrolyte, has been observed, which has not been given a convincing reason so far. In this article, we investigate the probability of quantum tunnelling of proton or deuteron for pass-through of the Coulomb barrier of palladium nucleus. This entry of proton or deuteron in the nucleus causes the neutron to exit from the nucleus. According to the Empire software results, just (^{105})Pd can produce neutrons by the quantum tunnelling phenomenon. The calculation results for this neutron production rate per unit of time agree with its experimental results.

This article carried out the Lax pairs and infinite conservation laws of the stochastic potential Korteweg–de Vries (spKdV) equation, which claims its integrability in the Lax pair sense. The infinite conservation laws of the spKdV equation were established using its Lax pair. The Darboux transformation was conducted and several pertinent theorems and propositions were briefly discussed for deriving especially the complexiton-type solutions. Some complicated efficient solutions, such as higher-order positon, negaton, hybrid positon-rational solution and negaton-rational solutions were explored from the spKdV equation by choosing initial trivial seed solutions.

The major objective of this study is to create solitary pattern solutions to the generalised KdV–Zakharov–Kuznetsov equation and fractional-order Triki–Biswas equation using an iterative procedure known as the residual power series method (RPSM). The efficiency of the suggested technique has been demonstrated by example considerations and the results have been graphically demonstrated. This article also discusses the numerical solution of the technique presented. The current method has been demonstrated to be reliable, highly effective and straightforward and can be used in numerous forms of fractional differential equations developed and in scientific domains.