Pramana最新文献

Photovoltaic materials are highly effective for solar cells, offering high efficiency and stability. Quantum theoretical analysis of phosphides [Sr₃Sn₂P₄]: Eu³⁺ for their potential in photovoltaic applications is reported here for the first time. Quantum computations for Sr₃Sn₂P₄ optoelectronics, mechanical and transport properties were performed using the all-electron method. The calculations were performed using the generalised gradient approximation plus Hubbard potential U (GGA + U) method for the doped materials. Our research indicates that the Sr₃Sn₂P₄ band gap can be lowered from 1.65 to 1.0 eV by doping Eu³⁺. According to first-principles calculations, bands at the Fermi level are hybridised with Sr-d, Sn-p and P-p orbitals. Eu³⁺ doping enables fine-tuning of the material’s band gap, structure and optoelectronic properties of novel phosphides by expanding the material’s potential applications in the semiconductor industry. Furthermore, calculations of the transport properties using semi-classical Boltzmann theory reveal a consistent pattern of thermopower throughout the 100–800 K range, which opens the door to the potential use of these compounds as low-temperature thermoelectric materials. ZT calculations show that both materials have reasonably strong thermoelectric performance, with just a slight fluctuation (0.18) in the results throughout a wide temperature range. Additionally, a thorough examination of the transport properties indicates that the current series of materials is p-type semiconducting. Computational studies of optoelectronic and transport properties of energy-renewable devices allow experimentalists to explore novel uses for quick and atomic-level accuracy prediction of photovoltaic materials with diverse crystal structures.

This study provides a comprehensive analytical and graphical exploration of the solitary wave solutions to the (3(+)1)-dimensional Mikhailov–Novikov–Wang integrable (MNWI) equation. We thoroughly examine the solitary wave solutions, emphasising their nonlinear wave propagation, invariant shape and constant velocity. The MNWI equation is used to derive various analytical solutions, including soliton, periodic and rational wave solutions. Additionally, we obtain a heuristic solution for the ((3+1))-dimensional MNWI equation using the Hirota bilinear method, focussing on soliton wave dynamics. The analysis highlights both the mathematical framework and the physical implications of the solutions. By defining bounds on the system’s variables, we assess the overall stability through the Lyapunov function. Nonlinear wave propagation is shown to maintain stability, shape and velocity under bounded conditions. These findings confirm the essential properties and dynamics of solitons. Furthermore, the study reveals complex hybrid solutions through which wave interactions are studied. The outcomes of this work hold significant potential for modelling various physical and environmental phenomena, such as floods, tsunamis and large-scale fluid flows.

This paper explores the matrix modified Korteweg–de Vries (mKdV) integrable models using similarity transformations. The study employs the Lax pair formulation as a foundation, proposing pairs of similarity transformations to reduce the Lax pairs of the Ablowitz–Kaup–Newell–Segur matrix spectral problems, thereby deriving integrable matrix mKdV models. Four illustrative scenarios are discussed to present specific examples of these reduced integrable models.

This paper investigates the soliton dynamics of the geophysical Korteweg–de Vries (GKdV) equation, focussing specifically on different types of soliton solutions that emerge within its framework: trigonometric, hyperbolic and rational solutions. Specifically, the study aims to examine elementary tsunami patterns such as rough waves, singular solitonic waves, periodic waves, sinusoidal waves and kink patterns. The coastal regions have experienced extensive urbanisation and rapid population growth, driven by the advancements of global economy. Consequently, this region is particularly susceptible to severe damages from a range of natural disasters, with tsunamis posing a significant threat. This vulnerability is evident by the occurrence of several devastating tsunami events in the 21st century, which have highlighted the exposure of certain regions to such catastrophic events. In this study, both the first integral method and the sub-ODE method are thoroughly discussed and applied to the GKdV equation. These techniques are employed to derive and analyse exact solutions, providing a deeper understanding of the behaviour and dynamics of the equation in geophysical contexts. The obtained results will enrich the understanding of the dynamics of tsunami models and provide deep insights into the propagation of nonlinear tsunami waves. The Coriolis parameter and the velocity of the travelling wave are considered to have a significant impact on tsunami waves. This study further enhances the understanding of nonlinear wave properties in a geophysical context by integrating phase portrait analysis, waveform characteristics and stability evaluations.

We perform a Lie point symmetry analysis of a time-fractional potential Korteweg–de Vries (FP-KdV) equation with the Riemann–Liouville derivative. By transforming the dependent variable, we map the time-fractional FP-KdV equation to a nonlinear ordinary differential equation (ODE) of fractional order using underlying symmetry generators. We obtain the derivative in the Erdélyi–Kober operator. We then construct the solution of the reduced fractional ODE by applying the power series method. The conservation laws (CLs) for the time-fractional FP-KdV equation are determined via Ibragimov’s non-local conservation method to time-fractional partial differential equations (FPDEs). Solutions for FPDEs via CLs have yet to be explored. Additionally, we present graphical representations of the results obtained using the power series solution method.

In this paper, the spectral statistics of all the observed (3_1^ - ) levels in the odd–odd nuclei have been analysed in the framework of random matrix theory. Also, the possible effects of the shell model configurations, mass regions, theoretical quadrupole deformation, experimental half-lives and major decay modes on the statistical situations related to negative parity states have been studied. In order to prepare different sequences, we have used the latest available empirical data on the (10 le A le 250) mass region for 216 nuclei. Using the maximum likelihood estimation technique, the parameter of the Berry–Robnik distribution function in different sequences has been extracted and the statistical situation of these sequences in comparison with regular and chaotic limits is described. Our results show the maximum chaoticity for these odd–odd nuclei in (100< A < 150) mass region, short-lived nuclei. These odd–odd nuclei have the maximum theoretical quadrupole deformations. Also, there are some suggestions on the effect of shell model configuration and decay modes on the statistical situation of these negative parity states in odd–odd nuclei.

This paper examines the effects of nonlinear radiation, heat sources, binary chemical reactions, Soret number, Dufour number and Arrhenius activation energy on Williamson fluid, as well as the transport of heat and mass via a circular porous radially stretched sheet using magnetohydrodynamics (MHD). It also applies a changing magnetic field to the circular, porous, stretched sheet. The similarity transformation transforms the nonlinear controlling boundary layer partial differential equations (PDEs) of momentum, temperature and concentration into a set of nonlinear ordinary differential equations (ODEs). The MATLAB bvp4c method then numerically solves the ODEs. We use graphs to illustrate the variations in flow, heat and concentration profiles resulting from various problem-related parameters, such as the Weissenberg number, magnetic parameter, Prandtl number, heat source, Eckert number, Soret number, Dufour number, radiation, temperature ratio, activation energy and chemical reaction parameters. We showed the effects on the skin friction coefficient, heat and mass transfer rate using tables for various values. When the porosity parameter, magnetic parameter and Weissenberg number increase, the fluid velocity drops. The temperature of the fluid increases as the Weissenberg number rises. As the activation energy parameter increases, the concentration profile increases. When compared to previous studies, the new results are considered quite good. Additionally, this work offers an intuitive explanation of the nonlinear radiation events in the Williamson fluid. With the ability to increase thermo-fluid flow system efficiency, the Williamson fluid has several applications in food industry, biomedicine and engineering appliances.

Researchers have investigated the suppression and survival of bottomonium in relativistic Heavy-Ion Collisions (HIC) to understand Quark-Gluon Plasma (QGP) characteristics better. The interplay between dissociation and recombination in QGP is typically explored using the Boltzmann transport equation, with a particular focus on the dissociation rates of newly formed bound states. This study considers the cumulative effects of gluon-induced dissociation, colour screening and recombination on bottomonium production in HIC. The model uses parameters of Xenon-Xenon (XeXe) collisions at (sqrt{s_{text {NN}}} = 5.44) TeV from the Large Hadron Collider (LHC). By employing the Bateman solution method to calculate recombination rates, this research provides a detailed analysis of the recombination and dissociation dynamics of the QGP and how they impact the bottomonium states in medium-sized collision systems like XeXe. The model successfully explains the observed suppression of (Upsilon (nS)) states in such a system.

Advancements in network science research have enriched our understanding of the mechanisms shaping the topological properties of networks over the past two decades. However, the existing models still grapple with limitations in fully capturing the diverse structures and behaviours observed in real-world networks. This paper addresses these limitations by examining network growth in networks characterised by a distinct in-degree distribution, exhibiting expected new edges in the head and an extended exponential or power-law behaviour in the tail. To overcome these complexities, we propose a comprehensive model encompassing non-constant edge establishment driven by mixed attachment and reciprocal mechanisms. This extension offers a more accurate representation of real-world networks. Utilising various discrete probability distributions, including Poisson, binomial, zeta and log-series, our model accommodates variations in the number of new edges, providing a realistic depiction of network evolution. Analytical expressions for the limit in- and out-degree distributions and evolving dynamics of cumulative complementary in- and out-degree distributions are derived. These findings enable a detailed assessment of each mechanism’s contribution to the head and tail of the in- and out-degree distributions. Furthermore, we validate the practical relevance of our model by fitting it to real-world networks, emphasising the impact of the number of new edges and reciprocity.

We investigate various nonlinear wave structures of the coupled Boussinesq system (CBS) using two efficient techniques: the auto-Bäcklund transformation and the Hirota bilinear method (HBM). Various travelling wave solutions, including kink waves, solitary waves with lump excitation and multi-shock waves, are obtained for the CBS using the auto-Bäcklund transformation. We also obtain the interaction between two-soliton solutions utilising this technique. Initially, we have shown that the CBS passes the Painlevé test for integrability. Then, we derive the auto-Bäcklund transformation for CBS through the truncated Painlevé expansion. Next, we observe the interaction and propagation behaviours of multi-soliton solutions for CBS using the HBM. The existence of multi-soliton solutions establishes that the CBS is also integrable in the Hirota sense. Interestingly, we observe that the HBM offers a more comprehensive framework for exploring diverse interactions between bright solitons and dark solitons, compared to the auto-Bäcklund approach. The multi-solitons and solitary waves with lump excitation obtained in this study can be used to describe surface water waves, while the kink wave and multi-shock waves represent topological changes in the water surface modelled by the CBS. Our findings on nonlinear structures for the CBS, provide valuable insights into the behaviour of nonlinear waves in water dynamics and are important for analysing various phenomena, such as ocean waves and waves in coastal areas.