Indian Journal of Physics最新文献

In this work, we have thoroughly investigated the bulk properties such as binding energy, neutron separation energy, nuclear radii and deformation parameter etc., along with the decay half-lives of various decay modes such as alpha decay and cluster decay of even-even ^238−338Rf isotopes. For that we have calculated the decay Q values using the calculated binding energy values which have been accessed by using two force parameters NL3* and NLSH in Relativistic Mean Field (RMF) Model. For the calculation of decay half-lives we have used Viola Seaberg, M. Royer, the Universal Decay Laws-1 and 2, Santhosh's semi-empirical formula, and the Unified formulae. From our investigation, we found possible shell or sub-shell closures at N = 136, 154/156, 162, 178, 184, 192, 218, 220, 222. With a comparison to alpha decay, we found the likelihood of occurrence of cluster radioactivity is significantly lower. The present analysis is informative for the near future experimental synthesis.

Half-Heusler compounds have garnered significant attention as versatile materials for an array of practical applications, including photoconductive devices, optoelectronic and spintronics. Current study aims to investigate the structural, electronic, phononic, optoelectronic and physio-mechanical properties of LiZnZ half-Heusler compounds. The density functional theory (DFT) based VASP and WIEN2k packages have been utilized. To treat the semi-conducting features three potential schemes (GGA, WC, TB-mBJ) have been incorporated. The computed elastic constants and phonon band structures of fully relaxed unit cell substantiate the mechanical and dynamically stability of compounds. Electronic attributes reflects that the variation in band gaps of LiZnSb compound has been observed with GGA (0.540 eV), WC (0.439 eV) and mBJ (1.417 eV) potential schemes while no effect of distinct potentials has been noticed on the behavior of LiZnBi compound. Moreover, the effect of pressure on the electronic and mechanical properties has been elaborated. The computed site effective charges via Mulliken and Loewdin schemes along with the crystal orbital Hamilton population analysis have been elucidated. The valence electronic charge density distribution has been analyzed by computing isosurface plots of electron localization function at valence band maxima and conduction band minima. The computed optical properties have been discussed with substantial details.

The predator–prey model is described by logistic differential equations, which capture the evolutionary dynamics of species. Incorporating multiple factors into predator–prey dynamics remains a critical and unresolved challenge in ecological modeling. In this paper, we propose a fractional-order predator–prey model based on prey logistic growth, incorporating the fear effect on prey, immigration factors, and cannibalism among predators. To account for memory effects, we apply two distinct fractional differential operators: the Caputo fractional derivative characterized by a power-law kernel, and the Atangana–Baleanu fractional derivative in the Caputo sense (ABC) characterized by a Mittag–Leffler kernel. We analyze the existence and uniqueness of solutions for the corresponding models under the Caputo sense and the ABC sense. For the model with the Caputo sense, we further examine the local and global stability of relevant equilibrium points and establish the conditions for the existence of Hopf bifurcations. Our results demonstrate that the Atangana–Baleanu derivative in Caputo (ABC) sense exhibits greater convergence of solutions compared to the Caputo fractional order. Numerical simulations reveal that the fear effect plays a stabilizing role in this model, while an increase in immigration factors tends to heighten instability. Additionally, the phenomenon of cannibalism can facilitate the persistence of species that are otherwise destined for extinction.

In this study, we investigate the ground state phase diagrams and magnetic properties of a two-dimensional ferrimagnet system characterized by alternating spins of values (sigma)= 3/2, and S = 3 on a square lattice, using Monte Carlo (MC) simulation. We examine the effect of exchange interactions, crystal field, and external magnetic field on magnetization, magnetic susceptibility, critical and compensation temperatures, and hysteresis behavior. We analyze the phase diagrams, specifically (T^{prime } - J_{2}^{prime }), (T^{prime} - J_{3} ^{prime}), (T^{prime} - D_{sigma } ^{prime}), (T ^{prime} - D_{s} ^{prime}), and (T ^{prime} - {h}^{prime}) under various values of the exchange couplings, crystal field, and external magnetic field. Our findings reveal that the compensation temperature starts to evolve significantly for (J_{2} ^{prime}) > 0.2 and (D_{s} ^{prime}) > − 3 of the spin-3 assembly. In contrast, the exchange interaction (J_{3} ^{prime}) and the crystal field (D_{sigma }^{prime}) do not exhibit threshold values, resulting in a nearly constant compensation temperature. We observe the N-, Q- and P-type compensation behaviors in the system. Moreover, our results indicate that all phase transitions observed are second-order, with no evidence of a tricritical point.

Thermophotovoltaic (TPV) systems have attracted considerable interest because of their ability to efficiently convert thermal radiation into electrical energy, with significant implications for waste heat recovery, portable energy generation, and renewable energy applications. Enhancing the performance of TPV systems necessitates the development of selective and efficient thermal emitters that align with the spectral responses of photovoltaic cells. This study explores novel tungsten-aluminum nitride (W-AlN) selective thermal emitters, which are characterized by high hemispherical emittance within the targeted spectral range. Using numerical simulations, we propose two distinct architectural configurations: a planar multifaceted stack and a grating structure. Both designs undergo optimization through a genetic algorithm, incorporating a carefully designed fitness function, alongside detailed simulations utilizing the finite element method (FEM) to assess the thermal emittance accurately. These findings indicate that the proposed emitters achieve exceptionally high hemispherical thermal emittance, closely matching the optical response of InGaSb photovoltaic cells while exhibiting minimal directional dependence. Additionally, a thorough analysis of the TPV cell output power and conversion efficiency as functions of the emitter temperature revealed substantial performance improvements facilitated by these advanced structures. The innovation in this research lies in the unique emitter designs and optimization strategies, which collectively enhance the efficiency and scalability of TPV systems. These results highlight the significant potential of W-AlN-based emitters in advancing energy conversion technologies.

The gas puff z-pinch device is used to investigate the dynamics of injected plasma by neutral particles; during the injection of the plasma by the neutral particles, the temperature is lowered and the plasma density is increased. The snowplow model is used to simulate the gas puff z-pinch device and estimate the gas puff pinch parameters. The model takes into account the radial compression, the reflected shock wave, and the expansion phases. The electric circuit and momentum equations are used and solved numerically by the model. Furthermore, the relationship between the kinetic pressure and the β factor, which ranges from 0 to 0.9, is studied in the model. The model demonstrates how increasing the β factor and injected neutral gas reduces temperature and velocity. The pinching time is increased with increasing the β factor and reduced with increasing the injection time.

The structural, elastic, electronic, phonon, thermo-physical, and optical properties of hexagonal-type X₂N (X = Mn, Tc, and Re) compounds were studied within the framework of density functional theory using the generalized gradient approximation (GGA). The obtained lattice parameter values were in good agreement with the literature. To investigate the mechanical stability of the studied compounds, the elastic constant values of the three compounds were calculated and from these values, some stiffness constant values such as Bulk (317.49 GPa, 339.29 GPa, and 401.57 GPa for Mn₂N, Tc₂N, and Re₂N, respectively), Young’s (443.14 GPa, 438.11 GPa, and 542.84 GPa for Mn₂N, Tc₂N, and Re₂N, respectively), Shear modulus (174.83 GPa, 170.50 GPa, and 212.93 GPa for Mn₂N, Tc₂N, and Re₂N, respectively) values, and Poisson's ratio (0.27, 0.28, and 0.27 for Mn₂N, Tc₂N, and Re₂N, respectively), were also obtained. According to the calculated elastic constant values, all compounds are mechanically stable and ductile. In addition, the atoms are interconnected by ionic bonding. Electronic band structure calculation was performed to reveal the types of materials. All compounds were found to have metallic character due to the absence of a band gap. Phonon calculation was also performed, which gives information about the dynamic stability of the materials. X₂N (X = Mn, Tc, and Re) compounds were found to be dynamically stable since they have no negative branches. Thermophysical analyses revealed that Mn₂N has the highest Debye temperature of 760 K, thus indicating strong chemical bonding and high thermal conductivity. Finally, in optical investigations, the reflectivity, absorption, and optical conductivity properties of X₂N compounds were evaluated in detail, and it was found that these compounds have high absorption properties in the ultraviolet region.

Based on the extended Huygens-Fresnel principle and the second-order moments of the Wigner distribution function (WDF), we have derived the evolution expressions for the propagation factor (M²-factor and angular width) and the effective radius of curvature (ERC) of higher-order Laguerre–Gaussian correlated Schell-model (L_plGCSM) beams in non-Kolmogorov turbulence. The effects of the initial beam parameters and the parameters of turbulence on the propagation factor and ERC of the standard and elegant L_plGCSM beams have been thoroughly examined by a set of numerical examples. It has been found that, mainly because of the high-order Laguerre coherent factor, both standard and elegant L_plGCSM beams are superior to Gaussian Schell-model (GSM) beams and Laguerre-Gaussian correlated Schell-model (LGCSM) beams in reducing the negative impacts of turbulence. Additionally, the standard L_plGCSM beams exhibit less sensitivity to turbulence than the elegant L_plGCSM beams.

We employ a novel technique, the Daftardar-Gejji and Jafari method with predictor–corrector (DGJMPC) that combines the Daftardar-Gejji and Jafari Method (DGJM) with the fractional trapezoidal method to solve the fractional Bloch model. We examined the convergence and stability analysis of the proposed technique using the Lipschitz condition and Gronwall’s inequality. We compare our results with the existing method and the exact solution. The numerical results for various fractional order derivatives are presented through figures and tables with the help of MATLAB software.

Nowadays, achieving clean energy is one of the most important challenges in the world. Nuclear fusion, utilizing fusion fuels such as DT, D³He, and P¹¹B through heavy ion fusion, represents a promising clean energy source. This article presents the authors’ novel investigation into a six-layer fuel system, which incorporates a foam layer, subjected for the first time to irradiation from two heavy ions, Bismuth (Bi) and Cesium (Cs), at an energy level of 10 GeV. We calculated the energies produced from various physical interactions between these beams and the chosen fusion fuels. Moreover, we determined the deposited energies due to the Bi and Cs heavy ion beams with Bragg peaks by GEANT4 code. A significant challenge in energy deposition within the fusion fuel is the non-uniformity of beam radiation; thus, we employed a foam layer to mitigate these inconsistencies within the six-layer fuel structure. Furthermore, we examined the relationship between non-uniformity and the displacement of the fuel pellet. One of the basic issues in inertial fusion would be a spherically uniform target compression, which would be degraded by a non-uniform implosion to evaluate the non-uniformity of illumination on the target; we use the mean square root uniformity of the target. We found that the tolerable displacement of the target illuminated by the wobbling ion beams is approximately 77–87 (upmu m) in a fusion reactor.