Modern Physics Letters B最新文献

This research explores the dual-mode manifestation within the nonlinear Schrödinger equation, elucidating the amplification or absorption of paired waves. This study delves into the simultaneous generation of two distinct waves associated with the dual-mode phenomenon with three crucial parameters: phase velocity, nonlinearity and dispersive factor. The resulting wave phenomena from these solutions have implications across various fields, including fluid dynamics, water wave mechanics, ocean engineering and scientific inquiry. The study employs the modified Sardar sub-equation method to obtain the optical soliton solutions, encompassing various types such as dark, bright, singular, combo dark–singular, periodic singular and dark–bright solitons. The obtained results highlight the reliability and simplicity of the modified Sardar sub-equation method. Additionally, the paper delves into the parametric conditions crucial for shaping and sustaining these solitons. The research explores the interaction of dual waves and the variation in wave speed. Furthermore, dynamic phenomena are illustrated, and the physical implications of the solutions are interpreted using 3D and 2D plots with different parameter values.

Hydrogen sulfide (H₂S) detection with novel sensing properties such as higher response and minimum detection limit at room temperature is essential to ensure the safety of humans and the environment. A hydrothermal method was utilized to synthesize NiO–ZnCo₂O₄ heterostructures. The purpose of these materials was to fabricate gas sensors and detect different hazardous gases. The intrinsic properties of synthesized products were studied to check the microstructure and morphological properties of the heterostructures. Different gas sensors performed gas sensing properties, and the significant properties such as high response (ratio of response in gas and response in air $R_g∕R_a=290$) towards 20$$ppm H₂S, short response/recovery time (32/20 s), a low detection limit (0.5 ppm), and great selectivity were detected based on the gas sensor of NZCO-5 (5% NiO–ZnCo₂O₄) compared with other sensors NiO, NZCO-0 (0% NiO–ZnCo₂O₄) and NZCO-10 (10% NiO–ZnCo₂O₄). The significant H₂S gas sensing improvement in this study could be a potential route for saving human lives.

This study presents an astrophysics-inspired transit search optimization (TSO) algorithm based on exoplanet search divided into five phases: galaxy phase, star phase, transit phase, neighbor phase and exploitation phase for effective parameter estimation of fractional Hammerstein control autoregressive (Fr-HCAR) systems. Various physical phenomena and real processes can be modeled with Fr-HCAR systems and estimating the Fr-HCAR parameters becomes a vital task. The mean-square error (MSE)-based criterion function is developed, and efficacy of the TSO for Fr-HCAR identification is deeply analyzed for different fractional orders, disturbance levels and degrees of freedom. The TSO remained accurate, convergent, robust and stable for all variations in Fr-HCAR but the accuracy level degrades a little bit for high disturbance and increased degrees of freedom. The reliability and trustworthiness of the TSO for Fr-HCAR identification are endorsed through statistical analyses conducted on sufficient autonomous executions of the scheme.

Considering the development of ultra-wideband detection technology, the effective attenuation performance of conventional electromagnetic absorbing materials prepared by component-morphology method is still affected by narrowband, which hinders its application. An effective strategy is to develop nanomagnetic metal absorbent that can effectively overcome skin effect through fine control based on nanotechnology. Mulberry-like Fe nanoparticles based on the self-assembly of spheroid blocks were synthesized in a simple chemical reduction process supplemented by a magnetic field. In view of synergistic loss of magnetic metal Fe, and unique physical properties of nanoparticles, the mulberry-like Fe nanoparticles exhibited attractive wave-absorbing properties. At a thickness of 3$$mm, the minimum reflection loss (RL) reaches −29.57$$dB, and the bandwidth less than −10$$dB reaches 8.38$$GHz, which covers the entire X-band, most of the C-band and part of the Ku-band. This will make it possible for electromagnetic protection and electromagnetic stealth. A possible growth mechanism was proposed to provide theoretical guidance for the subsequent preparation of nanomagnetic metal absorbent.

Marine propellers operate under severe service conditions and experience various corrosion forms. Electrochemical, mechanical, and biological corrosion are the three main common types of corrosion that occur on marine propellers. Electrolysis (electrolytic corrosion), being one of the electrochemical corrosion forms, has been extensively observed on marine propellers. It is the forced introduction of an external current in metals when submerged in seawater. However, it has rarely been studied for marine propellers, mostly on underground pipelines. This paper investigates the effect of electrolysis on a chromium-containing coating on copper substrate by studying the surface and cross-sectional microstructure of the substrate. It is likely that cathodic disbondment caused by high alkalinity and hydrogen evolution at the defect location were the primary reasons contributing to the failure of the coating, and the silver-colored layer deposition around the delaminated area is the corrosion product of copper–chromium oxide. The purpose of this study is to understand the electrolysis corrosion mechanism on Cu substrate and to develop a highly effective anticorrosion coating for marine propellers.

Variational Integrator (VI) is a numerical technique, in which the Lagrangian of the system is used as the action integral. It is a special type of numerical solution that preserves the energy and momentum of the system. In this paper, we retrieve numerical solutions for heat and wave equation with the help of all possible combinations of finite difference scheme like forward–forward, forward–backward, forward–centered, backward–forward, backward–backward, backward–centered, centered–forward, centered–backward, centered–centered. We also use Lagrangian approach along with the projection technique to obtain approximate solutions of these linear models. This approach provides the best approximate solutions as well as preserves the energy of the system while the finite difference scheme gives only the numerical solutions. We also draw a comparison of existing exact solution with all approximate solutions for both models and provide graphical representation of these solutions.

The electrical and magnetic properties of strongly correlated manganese oxides originate from and depend on the coupling of spin, orbital, lattice and other degrees of freedom, and can also be controlled by external stimuli (such as a magnetic field). Here, the films have been prepared using spin-coating method to determine the role of Jahn–Teller (JT) distortion and double exchange (DE) interaction in electronic transport and magnetoresistance (MR) by magnetic field in La${}_{0.7-x}$Sm_xCa${}_{0.3}$MnO₃/SrTiO₃(001). The Sm-induced lattice distortion suppresses the metal-insulator transition temperature and increases the films’ resistivity, which is due to the weakening of the DE interaction between Mn${}^{3+}$–O${}^{2-}$–Mn${}^{4+}$ ions and the enhancement of the single electron bandwidth. Moreover, the MR can be increased to 96.5% and the AMR can be increased to 66.6% under 1 T magnetic field. These findings indicate the importance of JT distortion in multi-field control of hole-doped perovskite manganites.

The balance of nonlinearity and dispersion in optical fiber medium gives rise to a constantly propagating pulse. Such distortion less waves have attracted potential interest. The dynamics of optical solitons are governed by the nonlinear Schrödinger’s equation (NLSE). A modified form of NLSE which incorporates group velocity dispersion (GVD) and the Kerr law nonlinearity is recently adopted for the study of such waves. Here, we investigate the nonlinear Schrödinger–Hirota’s equation (NLSHE) using the Sardar subequation approach. Some novel solutions to the NLSHE corresponding to the bright, dark, kink, and cusp solitons have been reported. Additionally, the spatial and temporal dynamics of these solitons provide deep insight into the behavior of these solutions. The stability study is carried out via modulation instability (MI) concept. Our work might have benefits in the propagation of these pulses in the optical fiber for communication.

In this paper, we obtain normal dispersive ${𝒩}{ℒ}{\mathscr{H}}{𝒮}$ shock waves for $\varphi ({{𝒥}}_1),\varphi ({{𝒥}}_2),\varphi ({{𝒥}}_3)$ dam-break intensity by the nonlinear heat system. Then, we obtain super-fluid normal dispersive ${𝒩}{ℒ}{\mathscr{H}}{𝒮}$ shock waves for $\varphi ({{𝒥}}_1),\varphi ({{𝒥}}_2),\varphi ({{𝒥}}_3)$ dam-break microfluidics. Finally, we illustrate thermonormal ${𝒩}{ℒ}{\mathscr{H}}{𝒮}$ pressure of $\varphi ({{𝒥}}_1),\varphi ({{𝒥}}_2),\varphi ({{𝒥}}_3)$ wave energy with normal dam-break in shallow water.