Volume 77, Issue 12

A system of dusty plasma, containing negatively charged dust particles, Boltzmann distributed electrons and ions, is considered in a cylindrical set up and electrostatic wave modes have been studied in the presence of an external magnetic field. The dust particles are of two different sizes such that small grains are present in significant amount. Using Fourier transformation along temporal and azimuthal directions, linear dispersion relation is derived, which indicates the existence of two distinct wave modes for the stable case. Among the breathing and rotation modes, density profiles have been observed numerically for the rotation mode corresponding to the stable case. The density fluctuation of small grains is noticed to be more prominent than that of the big grains. In the presence of external magnetic field, large grains contribute very negligible magnitude of dust number density in those regions, where voids are generated by the small grains only. The effect of mode number on the dust density fluctuation as well as on the structure of density profile is observed. The magnetic field effect on dust void formation is also studied.

The present work reports results of spectral parameters of Zn-like, Ga-like, and Ge-like Re ions using the multiconfiguration Dirac–Hartree–Fock method. Energy levels, transition probabilities, weighted oscillator strengths, line strengths, and wavelengths are given for Zn-like, Ga-like, and Ge-like Re ions. Breit interactions and quantum electrodynamics corrections are taken into consider. Comparisons are performed between the calculated energy levels and wavelengths with other available values, which show that the calculated results are in good agreement with each other for Zn-like Re ions. And the spectral parameters of Ga-like Re and Ge-like Re are also calculated which are new and unpublished previously.

The propagation of nonlinear electrostatic ion-acoustic (IA) shock waves in presence of external magnetic field having Cairns–Tsallis distributed electrons and ion kinematic viscosity is investigated. In the linear regime, the dispersion relation of the ion acoustic shock wave is found to be modified by the external magnetic field. Adopting reductive perturbation approach, it is shown that the dynamics of shocks is modeled by a hybrid Ostrovsky–Burgers’ equation. The influence of relevant physical parameters such as nonthermality and nonextensivity of electrons, magnetic field strength, and ion kinematic viscosity on the time evolution of the shock structure is numerically examined. It is observed the present plasma system supports both compressive and rarefactive shock waves. Furthermore, the analysis is performed through dynamical system approach to elucidate the various aspects of the phase-space shock dynamics.

This paper provides a numerical solution for the free vibration of a rotating sandwich beam using FG-CNTRC as the face sheet in a thermal environment. The artificial spring technique is used to imitate classical and nonclassical boundary conditions (BCs) of the rotating sandwich beam. All materials of core and face sheets are considered temperature dependent. Employing the first-order shear deformation theory (FSDT) and Hamilton’s principle, the vibration equation of the beam is derived. Using the differential quadrature method (DQM), the discrete forms of vibration equations and numerical results of the current problem are presented. Then, the applicability of the proposed solution is verified by comparing the corresponding results available in the existing literature. The effects of the distribution of CNTs, thermal effect, rotation, core to face thickness, and geometric parameters on the free vibration of the beam are discussed. More significantly, the different types of FG-CNTRC face sheets produce unusual stiffness enhancement effects on the beam and lead to different stability domains of the beam. The advantage of the proposed method is that the solution for free vibration of the beam with various BCs can be calculated only by changing the stiffness of the artificial spring without re-substituting the BCs in the solution matrix.

In this paper, a nonlinear Josephson junction (JJ) based-Wien bridge circuit is analyzed and coupled in order to obtain synchronization through passive components. The electrical equations governing the operation of our circuit are obtained using the laws of electrical circuit analysis. Chaotic phenomenon is demonstrated in the proposed circuit using relevant indicators such as the phase portraits, bifurcation and the corresponding Lyapunov diagram. Several coupling topologies are considered to achieve the phase synchronization that provides a better understanding of the distribution of energy in the overall system. Additionally, the effect of the noise is considered which considerably brings an added value to the dynamic of the phase synchronization between oscillators. Full synchronization is observed when the resistor is connected in parallel with the inductor or capacitor while different results are obtained when the resistor is connected in series with the capacitor or inductor. Finally, fine-tuning and selection of coupling coefficients reflects a migration toward synchronization between two Josephson junction based-Wien circuits that imply the self-adaptation of the synapse when two types of synapses are active simultaneously.

We propose a straightforward generalization of axion-electrodynamics (AED) for the case in which a lepton Dirac field is present in the U 1 EM ${\left(1\right)}_{\text{EM}}$ gauge-invariant Lagrangian of the closed system. In the associated differential equations of motion we find that variations in the axion field give rise to modifications in the electric current and in the divergence of the axial current. In light of this, we interpret some possible Dark Matter (DM) phenomena. In particular, we discuss on general grounds (i) AED and DM, and (ii) DM axions interacting with leptons in a nonlinear electrodynamics background. We briefly comment on the conceivable application of this model beyond the subject of DM axions realized in condensed-matter physics.

The tuning of a defect mode in a photonic crystal (PC) is of high significance for filter and sensor applications. We here investigate the tuning of the defect mode of a defective ternary PC with a semiconductor and high critical-temperature superconductor layers. A ternary photonic crystal with the heterostructure (semiconductor/superconductor/dielectric) is assumed. The transfer matrix method is employed to investigate the transmission of transverse electric waves. The refractive indices of the semiconductor and superconductor layers can be tuned by changing the operating temperature and the hydrostatic pressure. The defect mode and transmission properties can be controlled by using the hydrostatic pressure, operating temperature, frequency and thicknesses of the heterostructure layers. The analysis is performed in the frequency range of 20–65 THz. The proposed structure can be utilized as a biosensor and a narrowband transmission peaks filter.

A cadmium ion (Cd 2+ ) sensor based on polyvinyl alcohol (PVA)/tetraethyl orthosilicate (TEOS)/3-aminopropyl triethoxysilane (APTES) film integrated Mach–Zehnder interferometer was fabricated and evaluated. The three core fiber (TCF) is spliced with two single mode fibers (SMFs), one end of TCF and SMF are spliced with enlarged taper, and the other end of TCF is directly spliced with another SMF. PVA/TEOS/APTES composite film is coated on the surface of TCF. When the Cd 2+ is adsorbed by the sensing film, the relative refractive index of TCF cladding changes, the output interference trough wavelength shifts. By monitoring the wavelength shift information of the interference trough, the concentration of Cd 2+ will be obtained. In the concentration range of 0–0.4 μM, with the increase of Cd 2+ concentration, the interference trough shows a red shift. The sensitivity and the detection limit of the sensor are 7 nm/μM and 0.0143 μM (1.6 ppb), respectively. The sensor has excellent selectivity and good pH stability. It has the advantages of easy preparation, simple structure, and has potential application for the detection of trace Cd 2+ .