Abstract: This study investigates the unsteady free-convective flow of an electrically conducting Casson fluid through a porous medium under the combined influences of Hall current, radiation absorption, Dufour effect, thermal radiation, Joule heating, viscous dissipation, and a homogeneous chemical reaction. The fluid motion is subjected to a uniform transverse magnetic field with variable permeability and oscillatory suction. The governing nonlinear partial differential equations for momentum, energy, and concentration are formulated and transformed into dimensionless form using appropriate similarity transformations. Closed-form analytical solutions are obtained through a perturbation method applied for small fluctuations in permeability. The analysis highlights the roles of key parameters—including the Hall parameter (m), magnetic parameter (M), Dufour number (Du), Prandtl number (Pr), Schmidt number (Sc), thermal and solutal Grashof numbers (Gr, Gm), chemical reaction rate (Kc), radiation parameter (Q 1 ), Joule heating parameter, viscous dissipation parameter, and rotation parameter (R)—on velocity, temperature, and concentration distributions. Engineering quantities such as skin friction, Nusselt number, and Sherwood number are also evaluated. The results show that Hall current enhances secondary flow but increases skin friction, while Dufour effect, radiation absorption, Joule heating, and viscous dissipation significantly elevate fluid temperature. Chemical reaction accelerates mass transfer, and rotation reduces magnetic damping, lowering frictional resistance. These findings provide valuable insights for optimizing heat and mass transfer in MHD energy systems, thermal processing operations, and chemically reactive porous-media environments.

Abstract: In this work, a sixth-order compact finite difference method (CFDM6) is investigated to obtain the numerical solution of Benjamin–Bona–Mahony–Burgers equation (BBMBE). The compact finite-difference technique is used to approximate spatial derivatives at internal points and at the additional nodes. The time derivative is analyzed by a strong stability-preserving Runge–Kutta method of four stages and third order. The stability analysis of the proposed method is conducted to validate its stability. To validate the effectiveness and precision of the proposed method, the error norms L2 and L∞ are calculated for different illustrations. The analytical and numerical solutions from the literature are compared and presented in tables and graphs. The comparison shows that the computed values, are in good agreement, with the exact solution. This justifies the proficiency, precision, and computational implementation of the proposed method.

Abstract: The magnetocaloric effect (MCE) of Ni50Mn35Sn15 is investigated via phenomenological model (PM) at temperatures, ranging from around 5 K–400 K, validating both inversely and conventionally MCEs, corresponding to two magnetic transitions. Magnetic entropy change (ΔSM) is maximized at the antiferromagnetic transition in martensitic state with 14.5 J/kg.K, which is similar to prior work, demonstrating that PM is a good model for studying giant inverse MCE. However, |ΔSM| is maximized with 2.5 J/kg.K at the FM transition in the austenitic state. Consequently, PM is a particularly intriguing model in which both inverse MCE and conventional MCE for a single material at different temperatures can be examined. Ni50Mn35Sn15 is an efficient material for MR technology throughout widely temperature range, particularly ambient temperature and some temperature ranges that are near ambient temperature.

Abstract: A Conformal single layer ultra-thin dual band stop and bandpass Frequency Selective Surface (FSS) for microwave applications is proposed and experimentally evaluated in this letter. The proposed FSS uniquely combines dual passband functionality allowing the lower and upper WLAN spectra—with dual stopband performance that delivers wideband, wide-angle, and polarization-independent shielding for TE and TM polarizations. The proposed FSS consists of two Concentric Square Rings (CCSR) and two Convoluted Square Rings (CVSR) on a Rogers 3010 substrate of relative permittivity 10.2 and thickness 0.25 mm. The dimension of the unit cell is 0.1123 λo ×0.1123 λo, λo is the lowest resonant frequency. Planar and conformal FSS structures were systematically analyzed, fabricated, and characterized in an anechoic chamber to evaluate their passband performance and shielding effectiveness. The proposed FSS exhibits dual wide stopband characteristics ranging from 1.05 – 1.75GHz, 3.4 – 4.6 GHz with shield effectiveness of 51dB and 45 dB at 1.4 GHz, 4.06GHz respectively. It also exhibits dual pass band response from 2.2 – 2.5GHz and 5.4 – 5.9GHz within band with insertion loss of 0.8dB and 0.5dB respectively. It also exhibits outstanding angular and polarization stability up to 80 degrees. The close correlation between simulated and measured transmission responses validates the design’s effectiveness in shielding the L band and 5G NR spectrum while maintaining high transmission in the lower and upper WLAN frequency bands.

Abstract: This study presents an analytical investigation of oscillatory magnetohydrodynamic (MHD) flow of an electrically conducting second-grade fluid through a porous medium, incorporating the combined influences of velocity slip, thermal radiation, and a first-order chemical reaction. The governing momentum, energy, and concentration equations are formulated using the Boussinesq approximation and Darcy’s law, assuming laminar, incompressible, and time-dependent flow. Through appropriate similarity transformations, the system is reduced to a set of ordinary differential equations, for which exact solutions for velocity, temperature, and concentration are derived. The results reveal that magnetic field strength and buoyancy forces significantly suppress fluid velocity due to enhanced Lorentz and thermal resistance effects, whereas thermal radiation elevates temperature throughout the channel. Increasing the Schmidt number and reaction rate reduces solute concentration, indicating diminished mass diffusivity. Heat and mass transfer characteristics, quantified through Nusselt and Sherwood numbers, show that higher Prandtl numbers enhance thermal transport, while stronger chemical reactions lower mass transfer rates. The main novelty of this work lies in obtaining closed-form solutions for oscillatory second-grade fluid flow in a porous medium under the simultaneous effects of slip, radiation, and chemical reaction, offering benchmark results and valuable physical insights for applications in heat exchangers, catalytic reactors, polymer processing, and biomedical flow control systems.

Abstract: This manuscript theoretically investigates the stability of polaron in semiconductor quantum dot (SCQD) under the influence of the coupling coefficient of dimer parity-time (PT) symmetric. We have analytically solved the problem of two coupled lasers to calculate the eigenvalues and eigenvectors of different lasers and the intensities of the radiations emitted by each of them. Using the Lee-Low-Pines-Huybrecht (LLPH) method, we derive the ground and first excited state energies of polaron in different SCQD of our choice including Gallium Arsenide (GaAs), Cadmium Selenide (CdSe), Titanium Chloride (TiCl) and potassium bromide (KBr). Doing so, we chose to perform our study within three principal regimes of lasers: i.e. the PT symmetric domains ( γ = 1 ), close to the transition zone ( γ = 1.8 ) and above the transition zone ( γ = 3 ). The superposition of these two energy states forms a two levels system (TLS) which is considered as a quantum bit, allowing us to evaluate the probability density. Our results indicate that under threshold value ( γ t h r = 2 Ω ) , the system is PT symmetry and both KBr and GaAs are more relevant SCQD materials. Nearest the threshold, TiCl is especially relevant. Finally, beyond the critical point of coefficient gain-loss, CdSe is quite indicated when investigating the interaction of a PT symmetry coupled lasers. In addition to the above observation, we found coherent population transfer from the first excited state to the ground state and scattering phenomenon, showing that the polaron state can be controlled with PT symmetry coupled laser. These findings indicate that the coupling coefficient of dimer PT symmetric provides a means to manipulate the dynamics of polarons under laser radiation, offering potential applications in optoelectronics and quantum technologies. • The stability of polaron in semiconductor quantum dot is investigated. • The ground and first excited state energies of polaron in different SCQD is derived with the help of LLPH method. • When investigating the interaction of a PTS lasers, GaAs and KBr are more relevant SCQD materials under the threshold value ( γ t h r = 2 Ω ) • PT symmetric coupled lasers can be used to control the state of polaron in a system. • Coupling coefficient of dimer PT symmetric influences the dynamics of polarons under laser radiation.