International Journal of Modern Physics B最新文献

Recently, the research on the propagation of hot events has received widespread attention. By analyzing the data of hot events and the data of the common events in the same period on the network, we found that hot events usually break out quickly and opinion leaders and cluster behaviors exist in their propagation process. At the same time, the media public opinion fields of reporting hot events overlap and promote each other. Based on the common factors that drive an event to become a hot event, we used the heat calculation formula and entropy method to put forward the propagation model of hot events based on information coupling and information energy interaction. In the model, the coupling values of different event information are quantified based on the information fragment coupling effect. The heat calculation formula is used to dynamically adjust the propagation probability of different individuals in the propagation process of hot event, and the sensational effect threshold is introduced based on the overall energy value of the event. Finally, we used the real social relationship networks to simulate the evolution propagation process of the hot events, and compared it with the crawling real propagation curve of the events. The proposed model provides a good supplement for the study of the hot events.

The spin-5/2 Blume–Capel model was studied using the mean-field approximation and the Migdal–Kadanoff renormalization group method for two- and three-dimensional systems. We determined the phase diagrams in the (crystal field, temperature) plane where the system exhibited first- and second-order phase transitions as well as isolated critical, bicritical and triple points. In order to show first-order transitions at low temperature, we presented the total magnetization per site and the derivative of the free energy as a function of the crystal field. Moreover, the critical exponents of the system were calculated by linearizing the renormalization transformation at the vicinity of the second-order fixed points.

In this paper, the investigation centered on examining a Maxwell fluid’s convective double diffusive flow carefully considers factors such as chemical reactions, radiation, and the presence of a permeable moving flat plate. Additionally, the study encompassed the effects of heat generation and magnetohydrodynamics (MHD). The governing equations, initially expressed as partial differential equations, were converted into ordinary differential equations using a similarity transformation technique to facilitate the analysis. The computational power of MATLAB’s BVP4C software was harnessed to solve this resultant system of ODEs efficiently. The outcomes of this investigation were presented in the form of graphical representations that vividly depicted the behavior of the flow field, energy conservation, and concentration profiles under various parameter combinations. The research findings were thoughtfully summarized in a table, offering a comprehensive overview of temperature, velocity, and mass profiles across various parameters. These parameters included the Deborah number, chemical reaction rate, Eckert number, Lewis number, Prandtl number, porosity parameter, and MHD parameter. A notable discovery emerging from this study was the inverse relationship observed between nondimensional concentration contours and the magnitude of the chemical reaction rate. Simultaneously, it was observed that higher values of the Maxwell fluid led to a rise in the thickness of the temperature boundary layer. These findings offer valuable insights into the intricate interplay of physical and chemical phenomena in convective flows involving complex fluid properties and boundary conditions. The temperature outline diminishes as the heat generation rate increases, while the concentration profile declines with an elevation in the chemical reaction rate.

We construct a class of nonlinear coherent states (NLCSs) by introducing a more general nonlinear function and study their nonclassical properties, specifically the second-order correlation function $g^{(2)}(0)$, Mandel parameter Q, squeezing, amplitude-squared squeezing and Wigner function of the optical field. The results indicate that the nonclassical properties of the new types of even and odd NLCSs crucially depend on the nonlinear functions. More concretely, we find that the new even NLCSs could exhibit the photon-bunching effect, whereas the new odd NLCSs could show the photon-antibunching effect. The degree of squeezing is also significantly affected by the parameter selection of these NLCSs. By employing various forms of nonlinear functions, it becomes possible to construct the NLCSs with diverse properties, thereby providing a theoretical foundation for the corresponding experimental investigations.

In this paper, we explore the application of nonlocal theory to analyze the phenomenon of coupled thermoelastic wave reflection in a semiconducting diffusive medium, considering its temperature rate dependence. The governing equations are deconstructed using the Helmholtz vector rule, allowing us to delve into the behavior of the system. By calculating the dispersion relation in terms of propagation speed, we investigate four coupled longitudinal waves alongside an independent nondispersive transverse wave within the local medium. The cut-off frequencies for each wave are discussed, shedding light on their characteristics. Furthermore, we delve into the phenomenon of coupled longitudinal displacement waves at the medium’s boundary. Analytical derivations of amplitude ratios are presented, accompanied by graphical representations of their behavior, focusing on a semiconductor material such as copper. We examine the effects of physical parameters, including the nonlocal and diffusive parameters, on the obtained results. It is important to note that the existing literature primarily lacks consideration of diffusivity and plasma transportation. Lastly, we validate our findings by investigating the conservation of energy within the system.

Trapping molecules in strong-field-seeking states is particularly attractive to scientists in the field of molecular optics. If the external field is strong enough, all molecules are strong-field seekers. Contrary to the weak-field-seeking states, molecules trapping in strong-field-seeking states can avoid the loss caused by the inelastic collision which is a stumbling block for evaporative and sympathetic cooling. Unfortunately, the formation of a magnetostatic maximum in free space is forbidden according to Maxwell’s equations and Earnshaw’s theory. In this paper, a dynamic magnetic trap consisting of three pairs of Helmholtz coils is proposed. The time-sequence control is given together with the distribution of the magnetic field in space. The influence of the switching frequency and electric current flowing through the wires on the number of trapped molecules is investigated. We obtain the changes in the locations and the phase-space distribution within a switching cycle by trajectory simulation. Finally, the influence of the time during which the field is off on the performance of our trap is studied.

In a Doppler-broadened ladder-type Rubidium atomic system $5S_{1/2}$–$5P_{3/2}$–$5D_{5/2}$, three-photon electromagnetically induced absorption (EIA) and transparency (EIT) in two schemes of two coupling lasers with different propagation directions are comprehensively studied. Two coupling fields are entangled tightly with each other and induce constructive interference such that we observe EIA as two coupling fields are counter-propagating. Two coupling fields are independent and cause destructive interference such that only enhanced EIT occurs when two coupling fields are co-propagating, although all of the Doppler-broadened atoms satisfy the condition for three-photon resonance. The experimental results are coincided with the numerically calculated spectra using the dressed perturbation method. The mechanisms of EIT and EIA could also be understood by the dressed-state pictures.

This study focuses on examining the hydrodynamic stability of an incompressible fluid flowing through a bidisperse porous medium. Specifically, the impact of slip boundary conditions on instability is investigated. The study looks at a scenario in which the Darcy theory is used for micropores and the Brinkman theory is used for macropores. An incompressible fluid is located within an unbound channel with a constant pressure gradient along its length in the system under investigation. The fluid flows laminarly along the pressure gradient, resulting in a stable parabolic velocity distribution that does not alter over time. Based on our observations, it appears that increasing the values of the slip parameter, permeability ratio, porous parameter, interaction parameter and Darcy Reynolds number leads to an improvement in the stability of the system. The spectrum behavior of eigenvalues in the Orr–Sommerfeld problem for Poiseuille flow exhibits significant sensitivity and is influenced by multiple factors, encompassing both the mathematical attributes of the problem and the specific numerical techniques utilized for approximation.

This study investigates the contemporary thermoelasticity theories in a photothermal semiconducting medium with voids influenced by the electromagnetic field. Boundary conditions of the phenomenon were based on the equations that regulate it concerning the stresses, carrier density, change in volume fraction field and temperature on the surface space. The equations were solved in normal mode technique, and the results are displayed by graphs. A comparison has been made with the findings of the literature when neglecting the new external parameters. The findings show that the presence or absence of electromagnetic field and carrier density significantly impacts on the phenomenon. From the results obtained, it is clear that the effects of electromagnetic field, carrier density, volume fraction and thermal relaxation times are very pronounced and applicable in diverse fields including geophysics, astronomy, engineering, biology, etc.

The spin information of Majorana zero mode (MZM) has important application value in distinguishing MZM from other zero energy states. We study the spin direction of the Majorana zero mode (MZM) localized in a vortex state in a topological superconductor. We find that the topological number of the magnetic structure of the MZM is zero. However, with an increase in the vortex radius, the magnetic structure of the electron oscillates between the antiskyrmion and skyrmion (starting with the antiskyrmion), while that of the hole oscillates between the skyrmion and antiskyrmion (starting with the skyrmion). The total magnetic structure of the electron is a antiskyrmion (the topological number is −1) while that of the hole is a skyrmion (the topological number is 1). We hope these new features provide more characters for detection and regulation of MZM.