Khazar University (Azerbaijani: Xəzər Universiteti, which directly translates as Caspian University) is a private university located in Baku, Azerbaijan.
Abstract This study tested accretion onto a charged scalar black hole (BH) model within a massive-gravity framework. In this context, the analysis emphasizes the detailed dynamics of infalling matter, the determination of sonic points, and the response of different test fluids under varying conditions. The background spacetime is described by a charged dilatonic BH solution, and the conservation laws for particle flux and energy-momentum are explicitly formulated to allow treatment as a dynamical system. By recasting the accretion equations into an autonomous system, the critical conditions corresponding to sonic transitions are systematically identified and analyzed. Also, many fluid models are considered, including isothermal, barotropic, and polytropic fluids, covering regimes from ultra-stiff to sub-relativistic. Each fluid model produces distinct modifications to the Hamiltonian trajectories and radial velocity profiles, thereby influencing the overall accretion pattern. The parameters of massive gravity, particularly $$c_1$$ c 1 and $$c_2$$ c 2 , shape the horizon structure, determine the positions of critical points, and potentially affect the formation and stability of accretion disks. The mass accretion rate, expressed in terms of metric function, fluid energy density, and radial inflow velocity, shows a decreasing trend with increasing $$c_1$$ c 1 and $$c_2$$ c 2 , which implies a reduction in accretion efficiency. Additionally, the radiative properties of thin disks, including emitted flux, disk temperature, radiative efficiency, and luminosity, are suppressed for higher values of these parameters. In this case, the results illustrate that massive gravity not only modifies the behavior of matter inflow but also substantially diminishes the radiative output, offering potentially observable differences that can distinguish charged scalar BHs in massive gravity from their counterparts in standard general relativity (GR). We also numerically model matter accretion via the Bondi–Hoyle–Lyttleton (BHL) mechanism in the framework of massive gravity, showing that the modified shock cone structure, mass accretion rate, and the resulting QPOs are consistent with theoretical expectations, and highlighting their observability and differences from GR.
Triboelectric nanogenerators (TENGs) are limited by poor charge retention and unstable output. This study investigates the effect of graphene oxide (GO) incorporation and environmental humidity on a nylon/polysiloxane-based TENG. Structural and chemical properties were analyzed using XRD, Raman, and FTIR, while SEM and photoluminescence (PL) were used to examine morphology and charge-trapping behavior. Electrical performance was evaluated through dielectric and TENG output measurements. An optimal GO loading of 0.05 wt
The nonlinear Schr & ouml;dinger equation and its generalizations are fundamental in soliton theory and nonlinear wave dynamics of optical systems. This paper deals with the integrable Fokas-Lenells (FL) equation, which describes the nonlinear propagation of ultrashort optical pulses in optical fibers. We obtain precise optical soliton solutions to the FL equation with the help of an extended Riccati equation mapping technique and an undetermined coefficients (UCs) method, with a systematic scheme for obtaining analytical solutions under some parameter conditions. To ensure accuracy and reliability in the analytical solutions, the differential transform method is utilized to find numerical solutions for comparison purposes. Physical aspects and behavior of the soliton solutions are also represented by visualizing two-dimensional, three-dimensional, and density plots of the impact of various parameters on the profiles of waves. The research illustrates a number of new families of traveling wave solutions, such as dark, bright, and combinations of dark and bright solitons, presenting useful insights on nonlinear wave propagation, interaction among solitons, and possibilities of their implementation in optical communications and photonic technologies. The originality of this paper is in the combination of an extended Riccati equation mapping method and the method of UCs to obtain novel exact soliton solutions of the FL equation, tested by numerical comparison and thorough visualization. This research not only enhances the theoretical basis of the FL equation but also provides new avenues for future work in nonlinear optics and mathematical physics.
Nickel manganese spinel ferrites (Ni0.3Mn0.7CexFe2−xO4, x = 0.0, 0.01, 0.02, and 0.03) with substitution of cerium (Ce) were synthesized by a hydrothermal technique and investigated to determine how the substitution of Ce affected the physical properties of the material samples. The samples were characterized by various techniques including X-ray diffraction (XRD) to observe the structure of the prepared material, scanning electron microscopy (SEM) to study the morphology, and Fourier transform infrared (FTIR) spectroscopy to determine the bands within the samples. Additionally, vibrating-sample magnetometry (VSM) was applied to investigate the magnetic characteristics including remanent magnetization (Mr), saturation magnetization (Ms), and coercivity (Hc). The material was found to have a face-centered cubic (FCC), single-phase structure, confirmed by XRD. An increase in cerium concentration resulted in an increase in the lattice constant from 8.36 Å to 8.61 Å. SEM images showed agglomeration of the nanoparticles, which varied in size. The FTIR spectrum showed that light was absorbed at wavelengths of 500–4000 cm−1. It was found that the band shifted toward a higher frequency when cerium content was added to the pure nickel manganese ferrites. As the scan rate increased, the specific capacitance decreased, and the loop area increased. The suitability of the synthesized material for use as an anode in storage devices was investigated via cyclic voltammetry (CV). The prepared samples were found to have specific capacitance of 578–892 F g−1, estimated through galvanostatic charge–discharge (GCD) and CV measurements.
This paper investigates the optical solitons to the M-truncated fractional (1+1)-dimensional nonlinear generalized Bretherton model with arbitrary constants. It is employed to forecast the movement of liquid droplets or gas bubbles in microchannels, which is crucial for drug delivery systems, biomedical diagnostics, and lab-on-a-chip technologies. We obtain optical soliton solutions using the extended hyperbolic function method (EHFM) and the modified extended tanh method (METM). Numerous solutions, such as singular, periodic-singular, bright, and dark optical solitons, are obtained from our investigation. The 2D graphical depiction of the solutions shows a variety of wave patterns that change with varied values of alpha and t. The wave's amplitude forms become more apparent as alpha and t increase. Using 2D plots, the comparison of fractional effects for the M-truncated fractional derivative is demonstrated by giving specific values to the fractional parameter.
