Indian Journal of Physics最新文献

This work examines the unstable nonlinear Schrödinger equation, which characterizes the temporal evolution of disturbances in marginally stable or unstable media. The ((frac{G'}{G},frac{1}{G}))-expansion method is employed to derive new exact soliton solutions, explicitly represented through exponential, trigonometric, and rational functions. These exact solutions are then compared with results obtained from the Levenberg–Marquardt artificial neural network and the split-step Fourier numerical method. Statistical analyses, presented through tables and graphs, show strong agreement between the exact solutions and those obtained using these methods. Furthermore, 2-D, contour, and 3-D plots are utilized to visually represent and validate the behavior of the solutions. The results demonstrate that the combination of the ((frac{G'}{G},frac{1}{G}))-expansion method, the Levenberg–Marquardt artificial neural network, and the split-step Fourier numerical method provides a robust and complementary framework for solving and analyzing the unstable nonlinear Schrödinger equation, offering reliable insights into its dynamic behavior.

The CaO-Na₂O-Al₂O₃-B₂O₃-Ho₂O₃ glasses (0 ≤ x ≤ 2 mol%) were fabricated via melt quenching technique. Comprehensive characterization revealed an increase in density, molar volume, and refractive index with rising Ho³⁺ ion concentration. Optical absorption spectra analysis yielded Judd–Ofelt parameters: Ω₂ = 6.4268 × 10⁻²⁰ cm², Ω₄ = 2.7468 × 10⁻²⁰ cm², and Ω₆ = 2.5888 × 10⁻²⁰ cm². These results indicate promising optical properties for CaNaAlB glass doped with 0.1 mol% Ho₂O₃. Experimental and calculated branching ratios for ⁵F₄ → ⁵I₈ transition is recorded to be 0.64 and 0.82 respectively. The stimulated emission cross-section for NaCaAlB glasses was 4434 s⁻¹, while the total radiative transition probability was 5294.48 s⁻¹. Chromaticity coordinates for NaCaAlB glasses doped with Ho³⁺ ions were calculated, confirming their potential for green lighting and eye safe laser applications.

This study investigates critical aspects of tsunami wave dynamics, highlighting their potential threat to coastal infrastructure. The model studied is a complex system governed by non-linear partial differential equations, forming the foundational structure for our exploration. The study delves into the impact of fractional orders on the shallow water wave equation associated with tsunami waves. The temporal variable is discretized using the finite difference method to solve the mathematical model, while the spatial variable undergoes discretization through radial basis functions (RBFs). The reliability of the computational code is confirmed by comparing it against a known analytical solution to an integer-order model. We explore the influence of time- and space-fractional orders, coast slope, and sea depth on tsunami wave velocity and run-up height. The results are presented through graphical representations, and tabular data support the findings. This comprehensive exploration contributes valuable insights into the intricate dynamics of tsunami waves, providing a deeper understanding of their behaviour under the influence of fractional orders and various environmental factors.

This study focuses on optical properties of Sm³⁺ doped two different lithium borate glasses. These optical glasses were prepared exploiting the conservative melt-quenching technique. Thermal stability and annealing temperatures were studied for all the glass samples. X-ray diffraction technique is used to examine the amorphous behaviour of glasses. The Fourier Transform Infrared approach enables the observation of the vibrational band locations exhibited by the host material. The chemical composition of these materials has been ascertained by using Energy-Dispersive X-ray Spectroscopy. Optical absorption and emission measurements were employed in optical research. The evaluation process involves determining various spectroscopic parameters from the absorption spectra, Judd–Ofelt (J–O) parameters (Ω₂, Ω₄, Ω₆), the nephelauxetic parameters (β) along with bonding parameters (δ). The calculation of radiative parameters, such as radiative transition probabilities (A_T), branching ratios (β_cal, β_exp), and stimulated emission cross sections (σ_p), were performed via J–O theory. The elevated stimulated emission cross sections (σ_p × 10^–22(cm²)) and optical gains ((σ_p × τ_rad) × 10⁻²⁵cm²s) suggest that 0.5 mol% of Sm³⁺ doped lithium carbonate mixed borate glass composition could serve as a promising gain medium for solid-state lasers. The visible luminescence spectra of all the glasses were used to determine CIE coordinates, CCT, and colour purity.

This study investigates the nonlinear dynamics of the glucose-insulin regulatory system using advanced fractional-order modeling that addresses the limitations of traditional integer-order models. Through the Caputo fractional derivative, the model captures long-term dependencies that are critical to understanding complex biological interactions. Two numerical methods are used to solve fractional differential equations: Adams-Bashforth-Moulton and Laplace-Adomian-Padé Method. This study compares these methods. With its predictor-corrector structure, the Adams-Bashforth-Moulton method offers superior accuracy, stability, and efficiency when handling chaotic and highly nonlinear dynamics. In contrast to Laplace-Adomian-Padé Method, Adams-Bashforth-Moulton has low residual errors and enhanced stability, whereas Laplace-Adomian-Padé Method is computationally efficient but has limitations in chaotic regimes. Furthermore, bifurcation analysis and Lyapunov exponents confirm chaotic oscillations, emphasizing the system’s sensitivity to parameter changes. Moreover, the researchers propose chaotic control strategies crucial for managing diabetes based on fractional-order modeling in biomedical systems.

The COVID 19 pandemic is still causing a huge global hit and every year it hits millions of individuals. In response to this, we have created a comprehensive mathematical model in order to explore how the virus can develop and implemented a number of scenarios of vaccination. Our consideration of COVID-19 distribution pattern has been made especially using strict mathematical tools, such as Laplace Adomian Decomposition Method (LADM) and Caputo-type fractional-order derivative operator. Critical interrelationship between levels of transmission and strategies of vaccination is highlighted in our simulations. The enhancement of the rates of vaccination becomes an extremely powerful tool to reduce and stabilize the outbreaks of infections, and the enhancement of vaccine efficiency accelerates the process of containment of the virus. More importantly, the effectiveness of integer-order vaccinations in curbing transmission deserves mentioning, and the value of fractional calculus in optimizing the use of vaccines globally is beyond doubt. In essence, our results demonstrate the need to take measures to help reduce the rates of infections and recovery rates of the partially or un-vaccinated individuals. It requires strict complying with the regimens of booster doses, the continuous observation of protective prevention methods, and comprehensive educational efforts dedicated to popularizing the importance of booster vaccination among patients after treatment. The information presented in our analysis is beneficial to the health authorities when it comes to predicting the future of developments and the creation of effective eradication plans based on the current struggle against COVID-19 in Lagos, Nigeria.

The objective of this research is to develop models of anisotropic and spatially homogeneous Bianchi type-V Renyi holographic dark energy utilizing the Brans-Dicke theory. To achieve this goal, we consider both the Hubble and Granda-Oliveros horizons to be the cutoff for IR. The metric potentials are postulated to exhibit a correlation that results in an exponential solution and rapid expansion, so achieving a definitive solution for the field equations of the models. To analyze the physical properties of our DE models, we determine cosmological parameters including Hubble, deceleration, statefinder parameters and a (omega _{de} -omega '_{de}) plane. In addition, we conducted an analysis of the squared speed of sound to investigate the stability of DE models.

In this paper, a theoretical study of the interaction of hadrons at high energies is carried out within the eikonal approach using a relativistic quasipotential in the Yukawa form. The application of the of two-particle unitarity conditions and analytical continuity in the high-energy region allows for an effective consideration of the structure of the scattering amplitude in the impact parameter plane. The dependence of the cross section and the ratio A(t)—the of the real part of the forward scattering amplitude to its imaginary part, on the momentum t are discussed. The slope of diffraction at a given energy depends slightly on t. In more peripheral interactions, the nature of the potential does not affect the value of A(t) to the same extent as the momentum transfer. In the Oriar region, with increasing energy, the slope of the diffraction peak increases, indicateing that particles with small transverse moment become easier to scatter. By using the total angular momentum as a relativistic dynamic variable and taking into account the minimum value of this moment, beyond which partial waves contribute negligibly to the amplitude, an expression is derived for the effective interaction radius in the relativistic case. It is shown that the interaction radius cannot increase significantly with increasing energy, since this would lead toan unrealistic swelling of the particles. The physical interpretation of the results indicates that the qualitative scattering picture is valid for a broader class of strong potentials that decay rapidly at infinity. The obtained results are applied to elastic (p,p) scattering.

In this paper, a novel multi-band Ge₂₀Sb₁₅Se₆₅ glass-based dual-core photonic crystal fiber polarization beam splitter (DC-PCF PBS) with filled liquid crystal has been proposed. Based on the DC mode coupling theory and the full vector finite element method, the characteristics of the proposed DC-PCF PBS are calculated and analyzed, and the cores A and B have three different splitting bandwidths (SBs), respectively. When the splitting length (SL) is 7687 μm, the SBs of the cores A and B are 21 nm (1.415–1.436 μm), 23 nm (1.574–1.597 μm), and 13 nm (1.707–1.720 μm), and 29 nm (1.354–1.383 μm), 16 nm (1.577–1.593 μm), and 15 nm (1.733–1.748 μm), respectively. The total SBs of the cores A and B can reach 57 nm and 60 nm, respectively. The maximum insertion losses (ILs) of the X-pol and Y-pol in the different SBs are 1.31 and 0.88 dB, respectively. By introducing the fabrication process of the proposed DC-PCF PBS, the limitations and requirements of the current fiber testing process on the actual SL are analyzed and discussed. The structural characteristics, splitting bandwidth, max IL and other performance are compared with the results reported in recent years. Finally, a novel DC-PCF PBS with simple structure, multi-band polarization splitting, wide total SB, low IL, and more suitable SL for practical testing techniques is obtained. It not only works in the second near-infrared (NIR-II) window (900–1900 nm) but also has the advantages of simple fabrication, a wide application range, abundant bandwidth resources, high practicality, and easy integration with all fiber networks. This DC-PCF PBS may play a key role in fields such as single polarization fiber lasers, polarization sensitive optical coherence tomography (OCT), and fiber optic biosensors. In addition, it has the potential to play an indirect role in biophotonics fields such as OCT based animal neuron activity monitoring.

Graphene platelets (GPLs) and carbon nanotubes (CNTs) are ideal fillers to develop new-generation advanced nanocomposite materials with excellent performance due to their exceptional thermal and mechanical properties. However, investigations on the transient thermoelastic behaviors of nanocomposite structures remain scarce at present. This study extends on this field by analyzing the thermoelastic wave propagation characteristic of a beam reinforced simultaneously by GPLs and CNTs based on the Timoshenko beam theory and Lord-Shulman (L-S) generalized thermoelastic theory. According to the distribution patterns of GPLs/CNTs along the thickness direction, the nanocomposite beam is functionally graded (FG). The effective elastic modulus is assessed using the Halpin–Tsai micromechanics model, while the other properties are calculated using the mixture law. The dispersion relation for thermoelastic wave is obtained via the eigenvalue method. The results show that the FG-A reinforcement configuration yields superior frequency performance compared to the other distributions (UD, FG-O and FG-X). As the volume fraction gradient index of the reinforcement phase increases, the frequency for (i) FG-A rises, and (ii) FG-O and FG-X decreases. Increasing the GPL mass fraction further enhances the beam frequency, while it weakens for higher initial temperatures and thermal relaxation times. Moreover, for a beam length-to-thickness ratio in the range of 5–15, the dispersion relations for the different distributions exhibit clear variations. These results provide new perspectives for the design and optimization of high-quality nanocomposite beam structures.