Journal of Experimental and Theoretical Physics最新文献

We suggest a system of heterogeneous limit-cycle oscillators with a nonlinear global coupling that is equivalent to the Kuramoto phase model in its long-term dynamics. The continuum limit of our system yields directly the well-known equation for the Ott-Antonsen ansatz in a consistent way, confirming implicitly the validity of the ansatz assumption. For a Lorentzian frequency distribution of the individual oscillators, in particular, the nonlinear evolution of the order parameter is determined simply by a low-dimensional dynamical system, without assuming the Ott-Antonsen ansatz, and we present a complete spectrum analysis for the linear stability. For arbitrary frequency distributions, we derive the characteristic equations for the discrete spectrum as well as the continuous spectrum for the partially synchronized state. Possible extensions to variants of the Kuramoto model and linearly coupled oscillators are discussed.

This paper theoretically investigated the thermodynamic properties of nitrogen diatomic molecule using pseudo harmonic plus Kratzer potential (PKP). For this goal, the Schrödinger equation (SE) have solved with the combined potentials applying the series expansion formalism and have obtained energy eigenvalues for the N₂. Using determined eigenvalues, the partition function and thermodynamic properties such as mean energy, specific heat, Gibbs free energy and enthalpy have obtained and the calculated results have compared with experimental data. The comparisons reveal that there is a good agreement between them. Also, average deviations of the determined results and experimental data have obtained.

This study is devoted to theoretical investigation of the atomic and electronic structure of defect complexes formed by nickel atoms and oxygen vacancies in HfO₂ using the density functional theory. We consider Ni in the interstitial position as well in the Hf substitution position. It is shown that Ni facilitates the formation of oxygen vacancies and their clusterization. The localization of charge carriers occurs predominantly at oxygen vacancies, while nickel produces an indirect effect on the charge transport. Complexes of nickel and oxygen vacancies do not form shallow traps. It is shown that filamentary structures in the form of continuous chains in HfO₂ do not exhibit metal-type conductivity.

This research paper explores the dynamics of a cascaded optical klystron with betatron oscillations in free-electron lasers theoretically. By integrating multiple optical klystron stages in sequence, energy extraction efficiency and electron bunching are improved. An analytical treatment has been employed to evaluate spectral properties of the free electron lasers. The results demonstrate that the proposed configuration significantly enhances free-electron laser gain and intensity compared to the conventional single-stage optical klystron setup. The Liénard–Wiechert potentials and generalized Bessel functions have been introduced in the analysis. This study reveals that the cascaded optical klystron configuration serves as a highly effective method for improving gain efficiency and enhancing stability in free-electron lasers, even in the presence of the adverse effects of betatron oscillations.

The equation of motion of the director under torsional deformation of a nematic with a negative diamagnetic susceptibility is investigated by the stability analysis method. The case of an arbitrary orientation of the director relative to the magnetic field strength vector is considered. An expression is obtained for the turn-on time of the torsional deformation, which coincides with the expression for the turn-on time of the Fredericksz transition with an accuracy of up to the cosine of the angle between the magnetic field strength vector and the director. The studies conducted in a lyotropic nematic with negative anisotropy of the diamagnetic susceptibility in the disulfoindanthrone dye–water system show that the experimental results are consistent with the results of analysis.

One-loop electromagnetic corrections to the masses of the pseudoscalar (pi ), (K), (eta ), and (eta ') mesons have been calculated. For this purpose, the effective mesonic Lagrangian is used, the vertices of which are classified from the powers of momenta, masses of current quarks, and (1{text{/}}{{N}_{c}}). It is shown that the electromagnetic interactions lead to mixing of singlet–octet states. As a result, due to (U{{(1)}_{A}}) axial anomaly admixture, the contribution of virtual photons in elements (M_{{08}}^{2}) and (M_{{03}}^{2}) of the mesonic mass matrix is enhanced, which substantially suppresses the effect of isospin symmetry breaking in the whole. This mechanism is important in precision calculations with the participation of the ({{pi }^{0}}), (eta ), and (eta ') mesons.

In this study, cadmium zinc bismuth phosphate (CdBiZnP) glasses were synthesized using the melt quenching method, incorporating varying concentrations (0.1 to 1 mol %) of dysprosium (Dy³⁺) ions. The glasses were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, photoluminescence, and decay measurements. X-ray diffraction results confirmed the amorphous nature of the glasses. FTIR spectra revealed distinct vibrational peaks within the 500–2000 cm^–1 range. From emission data, chromaticity coordinates, correlated color temperature (CCT), and color purity were determined, indicating that all samples emit within the white light region on the CIE 1931 diagram, making them suitable for white light-emitting applications.

The high-temperature superconducting material Bi₂Sr₂CaCuO₈, (Bi-2212) holds major potential for advanced electronic and superconducting technological applications. The present study investigates the complete set of structural, electronic, and magnetic characteristics in Bi-2212 while focusing on interface and heterostructure features with Oxygen doping. The dominance of Cu orbital in the undoped system has been observed over the other orbitals. However, the oxygen contribution variation has been observed in the doped system with a tetragonal structure. Higher magnetic moments in the doped system resulted in the spin density modulation. The stripe order phases of Bi-2212 exhibit different local magnetic moments for Cu sites with a magnitude of ±0.58 μB alternating in the upper and lower layers. The decrease in Cu occupancy is due to the hole buildup. The band structure shows a maximum near k ≈ 0.2 and a minimum around k ≈ 0.8, indicating the electronic states’ energy variations. The local Cu–O bond length changed due to planar oxygen position alterations along the αalpha-axis. The role of different kinds of defects in the doped system is well analyzed. The presence of oxygen interstitials enhances the critical temperature and improves conductivity by adding more carriers to the material. The Bi-2212/Bi₃Se₃ exhibits the highest T_c, showing exceptionally strong effects through their critical temperature (96 K), resulting in a high electrical conductivity (5900 S/cm). The optical conductivity maintains a gradual upward trend, as it implies that improved carrier response occurs at elevated frequencies. Interactions between heterojunction materials lead to advancements that allow better superconducting electronics, quantum devices, and energy-efficient technologies.

This study investigates the performance of a newly designed high-porosity perforated-plate flow conditioner (HPPP) in improving flow measurement accuracy using orifice plates across a range of diameter ratios (β = 0.3–0.75). Experimental measurements were conducted to assess discharge coefficient deviations and axial velocity profiles downstream of the flow conditioners, with comparisons made against a standard Zanker conditioner and unconditioned flow. Results show that the HPPP conditioner consistently maintains discharge coefficient errors within the ±0.5% ISO 5167-2 tolerance for all tested β values, outperforming the Zanker design, particularly at low β where flow separation and sensitivity to disturbances are more pronounced. Velocity profile measurements further demonstrate the HPPP conditioner’s superior capability to restore flow symmetry and achieve a fully developed profile within a short downstream distance (x/D ≈ 9), as opposed to x/D ≈ 13.5 for the Zanker. These findings confirm the HPPP conditioner as an efficient solution for enhancing orifice flow metering accuracy across a broad range of flow conditions.