Chinese Journal of Physics最新文献

The nuclear ground state properties of ${}^{67-80}$As nuclei have been investigated within the framework of relativistic mean field (RMF) approach. The RMF model with density-dependent (DD-ME2) interaction is utilized for the calculation of potential energy curves and the nuclear ground-state deformation parameters (${\beta }_2$) of selected As isotopes. Later, the $\beta$-decay properties of As isotopes were studied using the proton–neutron quasi particle random phase approximation (pn-QRPA) model. These include Gamow Tellar (GT) strength distributions, log $\mathrm{ft}$ values, $\beta$-decay half-lives, stellar ${\beta }^{\pm }$ decays and stellar electron/positron capture rates. The ${\beta }_2$ values computed from RMF model were employed in the pn-QRPA model as an input parameter for the calculations of $\beta$-decay properties for ${}^{67-80}$As. The calculated log $\mathrm{ft}$ values were in decent agreement with the measured data. The predicted $\beta$-decay half-lives matched the experimental values within a factor of 10. The stellar rates were compared with the shell model results. Only at high temperature and density values, the sum of ${\beta }^{+}$ and electron capture rates had a finite contribution. On the other hand, the sum of ${\beta }^{-}$ and positron capture rates were sizeable only at low density and high temperature values. For all such cases, the pn-QRPA rates were found to be bigger than the shell model rates up to a factor of 33 or more. The findings reported in the current investigation could prove valuable for simulating the late-stage stellar evolution of massive stars.

Traveling wave solutions of fractional partial differential equations have great importance in the literature. The diversity of solutions plays an important role in understanding the physical structure of the model it represents. For this reason, two important differential equations with the fractional order, which have a significant role in applied sciences and can model real-life problems most accurately, have been solved by the generalized $\left(\frac{G^{\prime }}{G}\right)$-expansion method in this study. This method is a generalization of the classical $\left(\frac{G^{\prime }}{G}\right)$-expansion method. With this developed method, the non-linear fractional Schmael Korteweg–De Vries equation and fractional modified Liouville differential equations are discussed to find their exact solutions. In this way, new exact solutions of these equations that were not previously included in the literature have been found. The presented method has been applied to these two equations for the first time, and various new traveling wave solutions have been obtained. Thus, the study goes beyond other studies. To understand the physical behavior of these new exact solutions, three-dimensional graphs have been drawn according to different parameter values.

Based on a one-to-one mapping and Darboux method, 3D partially nonlocal dark-bright vector ring-like Peregrine structure solutions are derived. From these solutions, colorful excitations of dark-bright vector ring-like Peregrine structures in two kinds of diffraction control systems are studied. In the periodical system, periodically recurred fully excitations and inhibited excitations of ring-like dark-bright Peregrine structures are discussed. In the exponential system, inhibited excitations, peak-maintenance excitations and full excitations of ring-like dark-bright Peregrine structures are analyzed. The influence of diffraction parameter, radius parameter and thickness parameter of ring, and Hermite parameter on the formation of these excitations for dark-bright Peregrine structures are investigated. These results will deepen the comprehension of the partially nonlocal nonlinear wave in the fields of optical communication, cold atom and other domains.

The paper investigates the collapse of the generalized emergent Vaidya spacetime in the setting of $f(\bar{R},\bar{T})$ gravity, specifically in K-essence theory. In this study, the Dirac–Born–Infeld type non-standard Lagrangian is used to calculate the emergent metric ${\bar{G}}_{\mu \nu }$, which is not conformally equivalent to the conventional gravitational metric. We use the function $f(\bar{R},\bar{T})$ to reflect the additive nature of the emergent Ricci scalar ($\bar{R}$) and the trace of the emergent energy–momentum tensor ($\bar{T}$). Our study demonstrates that certain choices of $f(\bar{R},\bar{T})$ may result in the existence of a naked singularity caused by gravitational collapse. The alternative $f(\bar{R},\bar{T})$ values resulted in an accelerating universe dominated by dark energy. Moreover, the investigation showed the presence of both positive and negative masses, which might suggest the coexistence of dark matter and dark energy. In addition, when a certain amount of kinetic energy is present in the K-essence scalar field, mass is entirely converted into energy, indicating that spacetime is Minkowskian. The K-essence theory may also be employed as a dark energy framework and a basic gravitational theory, making it possible for researchers to investigate a wide ranges of cosmic phenomena.

The synchronization of neural networks is crucial for neural information processing and represents a key feature of various functional brain diseases. Memristors are ideal electronic components for mimicking biological synapses, among which discrete memristors have the advantage of fast computing speed and are often used in memristor-based neural networks. For these reasons, this paper proposes a novel discrete memristor-coupled Scale-Free neural network (DMSNN). Phase diagrams and time series of membrane potential are employed to analyze the firing pattern coexistence of individual neurons in the network. Furthermore, Spatiotemporal patterns, heat maps of the Spearman correlation coefficient matrix and the values of neuron membrane potential at a particular time point are adopted to declare the spatio-temporal dynamics of the complex neural network, encompassing asynchronization, chimeric state, synchronization and synchronization transition. The study also identifies the phenomenon of topology-induced coexistence and elucidates the underlying reasons for the emergence of chimeric states in the DMSNN as the coupling strength increases. Finally, a hardware implementation platform is constructed using a highly integrated SSD202 processor to validate the accuracy of the DMSNN. The results are consistent with the numerical simulations.

In this numerical study, we investigate the effect of aspect ratio (AR) on the natural convection (NC) flow and entropy generation (S_gen) in a stratified fluid confined inside a trapezoidal enclosure with thermally stratified side walls. The bottom of the enclosure is heated, and top of the enclosure is cooled. We use the Finite Volume Method (FVM) for simulating unsteady flows. We consider a Prandtl number (Pr = 0.71 for air) and explore AR of 0.2, 0.5, and 1.0, covering a wide range of Grashof numbers (Gr) from 10 to 10⁸. The outcomes are presented for Grashof numbers and the effect of the AR on fluid flow, rates of heat transfer (HT), and S_gen inside the enclosure. Critical Grashof numbers are identified, marking the shift in flow behavior from being influenced by baroclinic to Rayleigh–Bénard instability, and from a steady to an unsteady state for various AR. In the context of this transition to chaotic flow, several supercritical bifurcations are observed, including a Pitchfork bifurcation from symmetric to asymmetric states and a Hopf bifurcation from a steady state to an unsteady state. Additionally, we analyze the discrepancies in average entropy generation (S_avg) and average Bejan number (Be_avg) across the entire enclosure, considering various AR and Gr values. It is observed that for enclosures with Gr ≥ 10⁵, S_avg increases as AR decreases, indicating an enhancement in HT rate with decreasing AR. Furthermore, a quantitative relationship between S_avg, HT, AR, and Gr is presented. The study concludes that, as AR increases, the ecological coefficient of performance (ECOP) decreases, signifying a reduction in thermodynamics efficiency.

A hybrid differential evolution algorithm is used in this work to study the rotating transport of Falkner-Skan flow. The problem is modeled as an equivalent optimization problem by using Padé rational approximation functions. The primary model of the governing partial differential equations is imposed to subjugate the error between profiles. A hybrid evolutionary algorithm based on differential evolution and a convergent version of Nelder-Mead direct search algorithm is employed to perform global exploratory search along with an enhanced exploitation to improve the accuracy of the proposed solution scheme. The resulting scheme is named as evolutionary Padé approximation (EPA) scheme. The performance of the proposed EPA scheme on the Falkner-Skan boundary value problem is investigated by considering various values of the rotation parameters. The developed optimizer in EPA scheme was able to minimize the residuals up to${10}^{-10}$. Results are displayed graphically in order to study the effect of various types of parameters. EPA scheme determined that angular velocity increases or decreases accordingly as fluid parameter $\left(\beta \right)$ and the rotation parameter $\left(\lambda \right)$ but shows inverse behavior with respect to power law index$\left(n\right)$. Similarly, the response of velocity profile along $y-axis$ was decreasing function of $\beta$ as well as $n$ but increasing function of λ. The performance of the proposed EPA scheme has been demonstrated by comparing results with a hybrid neural network scheme and found in excellent agreement.

The study of bioconvection within porous medium saturated with a suspension of phototactic microorganisms is a research area of substantial importance, with wide-ranging implications in scientific and engineering disciplines. Understanding bioconvection in such systems is crucial for optimizing light distribution and reduces reliance on mechanical mixing. Hence, we examine the light-induced bioconvection in a suspension of phototactic microorganisms in an isotropic porous medium illuminated by collimated irradiation from above. The main objective of this study is to investigate the effects of key parameters such as the Darcy number, critical light intensity, and cell swimming speed on the initiation of bioconvection. The findings via linear stability analysis reveal that an increase in these parameters stimulates bioconvection, which leads to enhanced nutrient distribution within the medium. Additionally, the study reveals that the bioconvective solution transits from stationary and oscillatory types and vice-versa as the Darcy number increases. These results may help to optimize biofuel production and enhance industrial filtration processes.

We model the massive pulsar J0740+6620 and the light HESS J1731-347 compact object assuming (i) quark matter and (ii) dark energy stars. Within Einstein’s General Relativity, and assuming objects made of isotropic matter, we adopt analytic equations-of-state for both matter contents. Although the inner composition of the objects is very different in each case, both equations-of-state imply qualitatively very similar mass-to-radius relationships. We compute the spectra of radial equations for all four cases and the corresponding wave functions as well as the large frequency separations. A comparison between the different matter contents is made as well.