Pramana最新文献

Modifying electrical and optical properties in two-carbon materials is essential for electronic devices, energy storage and biosensor applications. We report a comparative study of the effect of systematically intercalated strontium atoms in AA- and AB-stacked bilayer graphene (BG) in the framework of density functional theory (DFT). The electronic band structures, the total and partial electronic density of states and the dielectric function are studied. We show that the intercalation of atoms can influence both electronic properties. Our results show that the Dirac cones, a signature of graphene, are translated into the conduction band. This property may be useful in band-gap tuning applications of nanodevices. The optical properties were calculated parallel and perpendicular to the graphene sheet under polarised electric fields. The calculated optical properties show that the intercalation of Sr in the AA- and AB-stacked BGs promotes IR absorption. The findings provide a basis for developing graphene intercalary compounds, which can be used in optoelectronics to control the absorption of light wavelengths and specifically in biosensor applications.

Oxygen packing factor (OPF) and atomic-level structure characteristics of the germania system at high temperature and pressure were investigated based on molecular dynamics (MD) simulation. Data analytic techniques, including Monte Carlo method, machine learning and data mining, were used to gain insights from the simulation data. We focus on elucidating the correlation between structure and OPF under high pressure. The research results have established the relationship of the network structure, polyamorphism, liquid–liquid phase transformations and microphase separation with OPF. The research findings revealed promising possibilities in developing novel materials and their applications.

The impact of magnetic field on the peristaltic motion of alumina/water ((mathrm Al_2O_3/H_2O)) and alumina/ethylene glycol ((mathrm Al_2O_3/C_2H_6O_2)) nanofluids in a vertical asymmetrical channel with mass/heat transfer was examined in this study. Unsteady governing equations were derived for the present problem. The Galilean transformation was used to transform the unsteady governing equations into steady ones. Reducing partial differential equations yields ordinary differential equations with the implementation of the long wavelength and low Reynolds number approximations. Coupled nonlinear differential equations (concentration and temperature equations) were solved analytically using the perturbation technique. In a similar fashion, the exact solution to the stream function is computed. MATLAB software was used to plot temperature, pressure rise, velocity and concentration, while MATHEMATICA software was used for generating streamlines. The findings suggest that, in comparison to the (mathrm Al_2O_3/H_2O) nanoliquid, the velocity profile for the (mathrm Al_2O_3/C_2H_6O_2) nanoliquid shows significantly larger magnitudes.

This study explores the chiral magnetic effect (CME) in ultra-relativistic heavy-ion collisions. The CME, observed as back-to-back charge separation along the magnetic field axis, is investigated using the newly developed sliding dumbbell method (SDM) applied to Au(+)Au events at a centre-of-mass energy (sqrt{s}_{text {NN}}=) 200 GeV generated by the AMPT model with string melting configuration. The CME-like signal is externally injected in the events by flipping charges of pairs of particles perpendicular to the reaction plane. The study reports a significant enhancement of the CME-sensitive 3-particle (gamma ) correlator in events with high back-to-back charge separation, in a given collision centrality. Additionally, a linear relationship is observed between the (sqrt{|gamma |}) correlator for the same-sign charge pairs and positive charge asymmetry ((langle A^{+}rangle )) across the dumbbell in CME-enriched sub-samples. Furthermore, the fraction of CME in (Delta gamma ) (difference between the opposite and same sign (gamma ) correlators) is presented across different collision centralities having different percentages of externally injected CME-like signal. Overall, the research aims to understand and detect the CME through innovative experimental method and detailed analysis of the event structure.

The present work deals with warm inflationary scenario from the viewpoint of non-equilibrium thermodynamics. Due to the interacting two-fluid system, the dissipative mechanism in warm inflation can be considered as effective bulk viscous pressure in second-order non-equilibrium description of thermodynamics. It is found that the interaction term is proportional to the enthalpy density of the formed particles. The warm inflation has been analysed using slow-roll approximation and an expression for the interaction term has been obtained. The formulation of warm inflation in the non-equilibrium thermodynamical prescription has been presented as a lemma. Lemma 2 shows the inter-relation between slow-roll approximation and quasistable radiation bath using the Friedmann equations. Finally, warm inflation has been examined from the point of view of swampland conjectures.

In the present investigation, we investigated the chemically reactive, laminar flow of a micropolar fluid over a stretching sheet in the presence of a transverse magnetic field, thermal radiation and the mutual effect of Soret–Dufour and viscous dissipation. The governing partial differential equations are converted into a system of nonlinear ordinary differential equations for finding the mathematical solutions and the transformed system is solved using the bvp4c algorithm in the MATLAB environment. Effects of different physical factors on dimensionless velocity, microrotation, temperature and concentration profiles are addressed and illustrated graphically. When the Schmidt number is low, it indicates that the momentum diffusivity dominates over the mass diffusivity.

The study aims at different families of analytical solutions and their dynamics for the ((2+1))-dimensional extended Boiti–Leon–Manna–Pempinelli (eBLMP) problem, which is widely used in the fields of physics such as non-linear optics, fluid dynamics, mathematical physics, plasma physics and quantum mechanics. The paper utilises two recently developed efficient mathematical methods: the generalised exponential rational function (GERF) method and the generalised Kudryashov (gK) method. These two methods are versatile, simply applicable to enlighten the new non-linear waveforms. Consequently, these discoveries enhance our understanding of complex systems like ((2+1))-dimensional eBLMP in the realm of non-linear science.

The multiple-relaxation-time (MRT) lattice Boltzmann method (LBM) is used in a suddenly expanded channel to demonstrate the flow of viscoplastic Bingham nanofluid with Al(_2)O(_3) nanoparticles. The geometry has two sections namely, inlet and outlet, and the corresponding heights are denoted by h and H, respectively. The length of the entire channel is 20H, and the expanded channel has a height of 16H. The purpose of the MRT-LBM simulation is to investigate the impact of changing the Bingham number (( 0 le Bn le 200)), keeping the Reynolds number (Re) fixed for different volume fractions ((phi =) 0.00 and 0.04). In addition, the consequences of variations in the Reynolds number (( 50 le Re le 1000 )) at constant Bingham number (Bn) are also studied for those two different volume fractions. The results demonstrate that with fixed (Bn=2), (Re=400) is the point where the flow pattern and recirculation regions are exactly the same for both volume fractions. An increase in Re causes the recirculation regions to grow for a fixed Bn for both volume fractions as Re’s rise increases the velocity and decreases the viscous force. Bn’s increment with Re and volume fraction unchanged lowers the recirculation region’s size due to a rise in viscous force. Higher Re and lower Bn cause the more significant recirculation regions to break down into smaller areas. Incrementing the volume fraction lowers size of the recirculation region. An unstable flow was observed for higher Bn (e.g., (Bn ge 100)) and lower Bn (e.g., (0 le Bn le 10)) when (Re ge 500) for both volume fractions in maximum cases. Unstable flow for lower Bn makes the recirculation regions asymmetric, and when Re is high, the recirculation regions break down for the base fluid ((phi =0.00)). When (Re=300) and (Bn=2), the length of the recirculation region of the upper wall decreases by (28.58%), and the length of the lower wall falls a bit less by (26.37%) when (phi ) is increased from 0.00 to 0.04. For (x/h=2), the nanoparticle mixed fluid’s velocity ((phi =0.04)) never gets a negative magnitude till the final position for (Re=700). In most situations, an increased volume fraction increases the skin-friction effect on both walls.

This paper explores the effectiveness of the Lie derivative discretisation scheme applied to two particular types of nonlinear dynamical equations, both of which have the characteristic of time variables in the denominator position. The discrete structure of non-autonomous systems is established. In particular, we exclude time variables as state variables to prevent non-autonomous systems from becoming autonomous systems. Using this method, we compute the numerical solution of the system above and compare it with the precise solution and the numerical findings of Runge–Kutta, demonstrating the broad applicability of the Lie derivative numerical algorithm. Finally, we determine the CPU consumption time of two numerical algorithms, thus providing evidence of the high efficiency of the Lie derivative numerical algorithm.

The interaction between a Riemann wave propagating along the y-axis and a long wave along the x-axis results in a generalised breaking soliton (gBS) equation. Lie symmetries of the equation are generated in this article to derive some rarely available classes of invariant solutions. The presence of arbitrary functions in each solution opens up a broad class of solution profiles. 3D profiles are used to explore more properties of the solutions to the gBS equation. The profiles describe doubly solitons, annihilation of parabolic, periodic solitons, line solitons and solitons on curved surface types. Solution profiles are useful in optical fibre, acoustic waves in a crystal lattice, long waves in stratified oceans, long-distance transmission and shallow water waves. The Lie symmetry approach has future scope to provide more variety in solutions due to the capability of solutions to include functions and arbitrary constants. This research effectively demonstrates the uniqueness of the solutions when compared with the previously published result. Moreover, the adjoint equation and conserved vectors are determined using Noether’s theorem.