The European Physical Journal Plus最新文献

Double-layer coated optical fibers provide vital protection against signal attenuation and mechanical damage, necessitating coatings that offer comprehensive surface coverage to meet stringent mechanical, chemical, and electrical standards. In the current study, a pressure-type die is utilized to coat double-layer optical fibers along with molten polymer, conforming to the Oldroyd 8-constant fluid model. The presented investigation analyzes the influence of magnetohydrodynamic effects during the coating process by leveraging a novel design of intelligent Bayesian regularization scheme (IBRS) to effectively investigate several important physical aspects. Adams numerical solver is employed to solve the associated differential systems, generating reference datasets for a double-layer optical fiber-coated model under various scenarios by variation of wall magnetic parameter, dilatant constant, pseudoplastic constant, and pressure gradient. These parameters play a vital role in enhancing the thickness of coated optical fibers, thereby implying their potential use as controlling parameters for thickness regulation. An intelligent solution strategy is implemented by using supervised artificial neural networks with IBRS. This approach enables immediate numerical approximation outcomes through simulations conducted on training, testing, and validation samples derived from reference datasets of complex geometry. The reliability of the IBRS networks is confirmed through convergence plots depicting mean squared errors (MSEs), effective outputs indicating adaptive control parameters of the optimization algorithm, and histograms based on errors and regression statistics derived from comprehensive simulation studies across several scenarios.

The conceptual design of an epithermal and fast neutron target–moderator–reflector (TMR) unit for the High Brilliance Neutron Source (HBS) project is presented. A total of 450 simulations with the Monte Carlo code PHITS were analyzed to explore different combinations and thicknesses of pre-moderator and moderator materials. For each case, the highest epithermal outgoing neutron current at the end of an extraction channel was obtained. Analysis of the outgoing current density showed that the neutron spectra are independent of the proton pulse width, while the integral outgoing current is proportional to the pulse width, indicating a trade-off between the time resolution obtained and the neutron flux per pulse expected at the sample position. The neutron time distribution analysis showed that (hbox {D}_2)O as pre-moderator, combined with (hbox {D}_2)O, ⁷LiF or graphite as moderators, will provide a competitive epithermal neutron current. The averaged epithermal and fast values obtained for the 96 Hz station and 167 (upmu )s proton pulse width are (9 times 10^{9},hbox {cm}^{-2},hbox {s}^{-1}) and (2 times 10^{10},hbox {cm}^{-2},hbox {s}^{-1}) for the epithermal and fast neutron extraction channels, respectively, with reductions expected for short proton pulses in burst-mode operation.

This paper proposes an innovative potential model, based on factorization with a screening term. The latter potential offers a rich and versatile framework that encompasses various classical potentials such as Coulomb, Kratzer, Yukawa, Hellmann and screened Kratzer potentials. This generalization makes our model particularly suitable for comprehensive studies of nuclear structure. After the exact separation of the Bohr Hamiltonian equation into its variables, the parametric Nikiforov–Uvarov (NU) method is employed, involving Greene–Aldrich approximation, to calculate the energy eigenvalues and wave functions. The results of the calculations are used to estimate the normalized energies of the low-lying states and the B(E2) transition rates of (^{192,194,196})Pt and (^{128,130,132})Xe isotopes. To assess the reliability of our model on the investigated isotopes, the numerical values of energy spectra and electric quadrupole transition rates are compared to experimental data and other relevant theoretical works. As evidenced by the values of the root mean square, our findings show excellent agreement with experimental data, underscoring the robustness and accuracy of our approach and the significance of the newly introduced potential.

A PT-symmetric model of three unidirectional coupled waveguides with Kerr-type nonlinearity and balanced gain and loss in edge waveguides is considered. During evolution, quasi-periodic breathers of two types with zero background may form in such a system. The modulation period for temporary breather oscillations strongly depends on the initial parameters of the incident wave. One type of breathers can interact quasi-elastically with each other, acquiring small changes in the amplitudes and velocities of incoming waves after a collision. The model can be useful in creating purely optical processing devices, for example, as an analog-to-digital converter.

In this study, calcite crystals within 42 lapis lazuli reference rocks coming from four distinct mining regions (in present-day Afghanistan, Tajikistan, Siberia and Myanmar) were characterised in terms of their compositional and luminescence properties in order to identify potential provenance markers. A non-destructive approach based on Ion Beam Analysis was employed, in particular using μ-Particle Induced X-rays Emission (μ-PIXE) and μ-Ion Beam Induced Luminescence (μ-IBIL). The results indicate that calcite crystals in Afghan rocks are characterised by the highest quantity of Mg and Mn; whereas, Siberian calcite exhibit the highest Sr content. The application of Principal Component Analysis also enhanced the possibility of discriminating between the Myanmar and Tajik rocks, as well as between the four provenances in general, by exploiting the compositional variability of Mg, Mn, Sr and Y elements. Regarding the luminescence properties, notable differences in the intensity ratio between the 360 nm and the 620 nm luminescence bands were detected among the provenances. In the second part of this study, the new results were employed to infer the origin of the raw material of certain archaeological findings discovered in two different historical sites: four lapis lazuli fragments from Shahr-i Sokhta (Iran, 3rd millennium BCE) and a lapis lazuli tessera from the city of Tanis (Egypt, 1050–700 BCE). The results of the analysis indicate that, among the four provenances considered in the reference rocks database, the best compatibility of the data from both case studies is found with the Afghan dataset. This suggests that the area of Afghanistan is the most probable source for the raw materials of the investigated findings.

Gravity quantization is regarded as a great challenge and being of fundamental importance in the modern physics. Recently, it has been found that entanglement induced by gravity can be generated in interferometric setups which may be used to examine the quantumness of gravity. In addition to entanglement, there are various diverse resources to manifest the quantumness of gravity. Herein, we investigate gravitationally induced uncertainty, coherence and complete complementarity relation (CCR) between two masses. The result shows that the gravitationally induced entropy-based uncertainty is highly insensitive to the reflectivity of beam splitter (BS). Importantly, we suggest the uncertainty relation can be used to entanglement witness in the current framework. Besides, we reveal that the relative entropy of coherence can approach to maximum in certain reflectivity of BS. Furthermore, the von Neumann entropy-based CCR is proved under quantum gravity, offering a powerful means for characterizing quantum correlations in bipartite systems. Thereby, we argue the current investigation offers insight into quantumness of gravity, and helps us better understand quantum gravity.

We explore analytically and numerically the dual role played by the next-next-nearest neighbor (NNNN) hopping coupling on the modulation instability (MI) and on the dynamics of breathers in 2D quantum ultracold atoms loaded in optical lattices. Via the linear stability analysis, it is shown that the dispersion relation formed exhibits intriguing forms. It is found that the emergence of MI regions and the growth rate may be significantly affected by the NNNN hopping coupling strength. To support the analytical studies, direct numerical simulations of MI are carried out to show the generation of a train of short waves exhibiting periodic W-shaped and V-shaped solitons with decreasing amplitude as time evolves. The appearance of breathers in the regions where the MI manifests is predicted to be influenced by the NNNN hopping coupling strength. By making use of Rayleigh-Ritz variational approach and in agreement with the MI analysis, the analytical results reveal the existence of the radial modes and discrete vortex solitons in called this framework, the dynamics of breathers. The accuracy of the outcomes is checked by numerical calculations which show a good agreement with the theoretical analysis.

In a previous study, it was shown that the generalized uncertainty principle can be derived from non-extensive entropies, particularly those depending only on the probability, denoted as (S_pm) in the literature. This finding reveals an intriguing connection between non-extensive statistics and quantum gravity. In the present work, we extend our previous result and derive a generalized energy-time uncertainty relation based on a measure of non-extensive entropies. Consequently, the dispersion relation undergoes modifications consistent with those obtained in other approaches to quantum gravity. We interpret these modifications as evidence of the non-extensive behavior of spacetime fluctuations at scales close to the Planck scale. While these effects are significant in this regime, they become negligible in the classical one, i.e., at low energies where the spacetime is smooth. As a consequence of the non-extensive behavior exhibited by spacetime at very small scales, the black hole radiation temperature undergoes quantum-level corrections, increasing in the case of (S_{-}) and decreasing for the case of (S_{+}). Moreover, the modified uncertainty relation derived here predicts a maximum uncertainty in energy, of the order of Planck energy, and a minimum time interval, of the order of the Planck time, offering new insights into the fundamental structure of spacetime in the quantum regime.

This study examines the effects of an external gravitational field on highly rarefied gases in the transitional-flow regime near the free-molecular-flow regime. In our theoretical study, we rederive the classical kinetic theory for an ideal gas in terms of the kinetics of the constituent particles to account for the effect of particle acceleration by an external gravitational field. Subsequently, we derive an extended expression for the virial pressure equation as a generic description of the dynamics under an external gravitational field. We employ the soft-sphere model for the following reasons: In highly rarefied gases, short-range and instantaneous collisional interactions are dominant. Thus, by expanding the asymmetric two-body potential in the virial pressure equation and retaining only the contribution of the short-range interaction, we can obtain a soft-sphere model that represents the interaction in the collision direction as a harmonic oscillation. In the absence of dissipation, the soft-sphere model has been confirmed to reproduce fully elastic collisions. In our collision simulations, we define two parameters. The first parameter represents the collision probability between each pair of approaching particles, and the second represents the ratio of the magnitude of the external potential energy to the total kinetic energy of the particles. The behavior of the system is analyzed by varying the values of these two parameters. Our analysis shows that if the external potential energy is sufficiently small (1%–5%) compared with the total kinetic energy, then a pressure difference emerges between the walls. However, the system retains the properties of equilibrium statistical mechanics, as indicated by the Maxwell–Boltzmann (MB) distribution. In conclusion, highly rarefied gases obey the MB distribution even when placed under weak gravitational fields.