International Journal of Modern Physics B

A systematic experimental investigation was conducted to study the effect of oxygen environment of different pressure on the fretting wear behavior of Ti6Al4V titanium alloy. In order to well probe the real tribo-chemical state, in this work, an in-situ X-ray photoelectron spectroscopy (XPS) analysis test developed by a self-designed high precision fretting wear tester integrated with an XPS equipment was used. The tribo-oxidation formed at the different oxygen pressure and its effect on the fretting wear mechanism and the resulting fretting wear volume in the different fretting run regime were discussed. Results show that the oxygen environment of different pressure has significant influence on the wear resistance of titanium alloy depending on the fretting run regime. In the partial slip regime (PSR), different oxygen pressure plays a little influence on fretting wear behavior, while a significant influence for the mixed fretting regime (MFR) and slip regime (SR). The tribo-oxidations produced at the oxygen environment of different pressure for the different fretting run regimes are found to correlate well with the resulting fretting wear mechanism and the fretting wear resistance.

The A, B and C atoms with spin-1/2, spin-3/2 and spin-5/2 are joined together sequentially on the Bethe lattice in the form of ABCABC$\dots$ to simulate a molecule as a triple mixed-spin system. The spins are assumed to be interacting with only their nearest-neighbors via bilinear exchange interaction parameter in addition to crystal and external magnetic fields. The order-parameters are obtained in terms of exact recursion relations, then from the study of their thermal variations, the phase diagrams are calculated on the possible planes of our system. It is found that the model gives only second-order phase transitions in addition to the compensation temperatures.

Main objective of this paper is to investigate comparative analysis of Copper-water and Copper Oxide-Water nanofluids flow due to a stretchable plate. Magnetic field is applied in transverse direction. Energy equation contains impacts of viscous dissipation and Joule heating. Appropriate dimensionless variables are used to transform the nonlinear PDEs system into dimensionless form. The dimensionless PDEs system is solved numerically by FDM (Finite difference method). Impacts of flow variables including Reynolds number, nanoparticles fraction, Hartmann number and Eckert number on velocity, surface drag force, Nusselt number and temperature are analyzed. Obtained outcomes show that velocity increases through Reynolds number and time while it decreases with Hartmann number. Temperature enhances with Eckert number while it decays with time. Skin friction increases for both Hartmann number and Reynolds number. Nusselt number decreases through nanopartical fraction. Comparative analysis of Copper-water and Copper Oxide-Water nanofluids shows that velocity and temperature are higher in Copper-water when compared with Copper Oxide-Water. For higher nanopartical fraction, the velocity and temperature decrease.

This paper examines nonlinear thermal radiative stagnation point flow of Walter-B nanofluid. The characteristics of nanofluid are explored using Brownian motion and thermophoresis effects. In the presence of uniform magnetic field, fluid is conducting electrically. Furthermore, phenomena of mass and heat transfer are studied by implementing the effects of chemical reaction, Joule heating and activation energy. Outcomes of distinct variables such as induced magnetic parameter, Eckert number, thermal radiation parameter, Weissenberg number, ratio of rate constant, heat capacity ratio, thermal Biot number, solutal Biot number, Prandtl number, heat generation parameter, Schmidt number on concentration, temperature and velocity distributions are explored. The numerical method is implemented to solve the governing flow expression. Further, Sherwood number, Nusselt number and skin friction coefficient are analyzed and discussed in tables. Weissenberg number have opposite behavior on velocity field while it increases for larger values of mixed convection parameter. Temperature of the fluid rises for higher values of thermal Biot number, thermophoresis diffusion coefficient, heat generation parameter and Eckert number Activation energy parameter and Weissenberg number have direct relation with concentration field.

The ground-state physical properties of compounds ${\mathrm{\text{NaInY}}}_2$ $(\mathrm{\text{Y=S, Se, Te}})$ are investigated using all electron full potential linearized augmented plane wave plus local orbital (FP-LAPW+lo) method. These properties include thermoelectric, optical, electronic and structural properties. The generalized gradient approximation (GGA) due to Wu Cohen (WC) exchange potential for the exchange correlation (XC) effects was used. The modified Becke–Johnson (mBJ) approximation has also been exploited for the precise measurement of XC energy. The stability of crystal structures in tetragonal chalcopyrite phase was determined by calculating the enthalpies of formation. The electronic properties have been studied by plotting the total density of states (TDOS) and partial density of states (PDOS) as well as band structures. These properties show that all compounds have direct band gaps. By exploiting the imaginary part of the dielectric function ${𝜀}_2(\omega )$, optical properties such as energy loss spectrum $(L)$, reflectivity $(R)$, extinction coefficient $(k)$, refractive index $(n)$, optical conductivity $\sigma (\omega )$ and absorption coefficient $(\alpha )$ were calculated. It can be seen that threshold absorption for all compounds occurs in the lower energy regions of solar spectrum. Thermoelectric properties like figure of merit (ZT), power factor (PF), electrical conductivity $(\rho )$, thermal conductivity $(k)$ and Seebeck coefficient $(S)$, were also calculated by employing Boltz Trap code. While studying transport properties, ${\mathrm{\text{NaInTe}}}_2$ was found to be comparatively more efficient than ${\mathrm{\text{NaInY}}}_2$ $(\mathrm{\text{Y=S, Se}})$ having maximum value of ZT. Therefore, first principle study of these chalcopyrite compounds revels that they are promising materials for photovoltaics in the infrared and visible part of solar energy.

In this study, we report, for the first time, on synthesis of lanthanum oxide ${\mathrm{\text{La}}}_2{\mathrm{\text{O}}}_3$ nanoparticles NPs by laser ablation in water without using surfactant. The effect of laser wavelength on the optical and structural properties of ${\mathrm{\text{La}}}_2{\mathrm{\text{O}}}_3$ NPs was investigated. X-ray diffraction studies show formation of polycrystalline lanthanum oxide with pure cubic phase and the crystallinity of the nanoparticles synthesized with $\lambda =532$ nm was better than that prepared with $\lambda =1064$ nm. The optical absorption investigations reveal that a strong absorption peak at 234 nm was observed for ${\mathrm{\text{La}}}_2{\mathrm{\text{O}}}_3$ NPs prepared at 532 nm laser wavelength. The optical energy gap of ${\mathrm{\text{La}}}_2{\mathrm{\text{O}}}_3$ NPs synthesized with 532 and 1064 nm laser wavelengths were 5 and 4.5 eV, respectively. Scanning electron microscope (SEM) investigation indicated the formation of nanoparticles with average particle size of 35 nm for ${\mathrm{\text{La}}}_2{\mathrm{\text{O}}}_3$ prepared with 532 nm and was 75 nm for ${\mathrm{\text{La}}}_2{\mathrm{\text{O}}}_3$ prepared with 1064 nm laser wavelength. The effect of laser wavelength on the optoelectronic properties of hybrid In/p-${\mathrm{\text{La}}}_2{\mathrm{\text{O}}}_3$/n-Si photodetector was studied. The responsivity studies of the photodetectors show the presence of two response peaks at 250 and 750 nm.

We investigate transmission and reflection properties of a broadband pulse with normal incidence on silicon-metal-silicon (SMS) for the first time, to the best of our knowledge. The results show that in lower frequency range, the transmission is close to zero, and the reflection and loss are in the range 0.50–0.90, 0.10 to 0.50, respectively. In higher frequency range, the transmission spectrum has two peaks, with transmittance 0.69, 0.90, and at same frequencies as the transmission peaks, the reflection spectrum has two troughs with reflectance 0.00, 0.02 and corresponding losses are 0.10, 0.29, respectively. This simple waveguide structure may have potential applications in silicon photonics, such as filters and laser oscillation cavities.

Thin plate-type acoustic metamaterials have the advantages of lightweight, high rigidity and adjustable parameters, showing great practical application values in sound wave control. In this paper, a type of perforated bi-layer plate-type acoustic metamaterials (PBPAM) is designed for low-frequency noise control. The sound insulation peaks can be increased by combining the perforated plate and synergetic masses, making the sound insulation performance close to the mass law at the resonant frequency. Compared to the results predicted by the mass law, a better performance of sound insulation is achieved based on the PBPAM. The effects of the structural parameters are investigated in this study. Based on the impedance tube experiments, the measured results have a good agreement with the simulated ones. This work can provide a reference for low-frequency and broadband sound insulation based on plate-type acoustic metamaterials in practical engineering.

The pattern transition of target waves in Hindmarsh–Rose neuron network exposed to fixed and periodic electromagnetic radiation is reported in this paper. Our numerical results confirm that local periodical excitation can induce stable propagating target waves from the network. It is found that fixed electromagnetic radiation has great effect on the propagating target waves, and that these target waves can be obviously blocked by increasing the intensity of fixed electromagnetic radiation. We find that the periodic electromagnetic radiation with appropriate amplitude and frequency can break the target waves and induce spatiotemporal turbulence and spiral waves from the broken target waves. Our numerical simulations show that the influence of periodic electromagnetic radiation on the dynamics of target waves is complex, and that although both increasing the amplitude and decreasing the frequency can break the target waves and induce spiral waves and chaos from the network, extensive numerical results find that lower frequency is more easy to terminate the target waves and generate spiral waves and spatiotemporal chaos. The numerical simulations also show that fixed and periodic electromagnetic radiation have influence on the pattern transition of the target waves in the network, but periodic electromagnetic radiation is more helpful to develop spiral waves and turbulence from the network.

The electronic structure, energy barrier and charge redistribution of cyclo[18]carbon and cyclocarbon oxides $({\mathrm{\text{C}}}_{20}{\mathrm{\text{O}}}_2$, ${\mathrm{\text{C}}}_{22}{\mathrm{\text{O}}}_4$, ${\mathrm{\text{C}}}_{24}{\mathrm{\text{O}}}_6)$ on NaCl(001) surface were computationally studied by using MOPAC. The HOMO electronics are mainly distributed at the inner and outer circumferential half circle of the cyclo[18]carbon along triple C–C bonds. However, the LUMO electronics are distributed at above and below surfaces of the cyclo[18]carbon circle along single C–C bonds. The energy barrier is different along different direction. The energy barrier of cyclo[18]carbon on the NaCl surface is the smallest (0.23 eV/per atom). When the cyclo[18]carbon and cyclo[18]carbon oxides molecular are put on the NaCl surface, they show different amounts of positive charge, no longer neutral.

The propagation of soliton through optical fibers has been studied by using nonlinear Schrödinger’s equation (NLSE). There are different types of NLSEs that study this physical phenomenon such as (GRKLE) generalized Radhakrishnan–Kundu–Lakshmanan equation. The generalized nonlinear RKL dynamical equation, which presents description of the dynamical of light pulses, has been studied. We used two formulas of the modified simple equation method to construct the optical soliton solutions of this model. The obtained solutions can be represented as bistable bright, dark, periodic solitary wave solutions.

The network structure acquires great influence on the traffic capacity for complex network. Since the nodes with high degree usually bear large load in the process of packet transmission, we propose a new multilayer network model which can balance the load of low-speed and high-speed layers. The simulation results show that compared with the randomly select nodes multilayer network model, the new network model makes the multilayer network load more balanced, thereby enhancing traffic capacity of the network and reducing the possibility of congestion. This network model gives full play to the transmission advantages of the high-speed layer of the multilayer network, and can reduce the consumption of resources while achieving the same transmission effect, which is of guiding significance for the planning of network lines.

The flow of viscous fluid between two parallel plates is investigated. The applications of the magnetic field effect have been considered in the vertical direction to the plates. Velocity has been presented in the presence of suction and injection. The temperature equation is assisted with the Joule heating effect. One of the numerical techniques, that is, finite difference approach has been used to tackle the given partial differential system. This method results in a system of simple algebraic equations. The unknown function is analyzed inside the domain. In this technique of solution, a system is subdivided into many smaller parts called finite elements. The obtained simpler algebraic equations are then assembled to form a system of equation which governs the original problem. The variational method is used to get an approximate solution by reducing the error function. The effects of pertinent variables on temperature and velocity are shown graphically in the discussion section. The obtained results show that the velocity decreases with magnetic and porosity parameters. Temperature increases for larger values of Hartmann and Eckert numbers.

In this paper, a new method is proposed to manipulate seismic Rayleigh waves using phase-gradient metasurfaces. This highly compact artificial structure enables the anomalous refraction of Rayleigh waves according to the generalized Snell’s law (GSL). The soil-embedded metasurface is composed of only one column of commercial rubber blocks, which can provide an accurate phase shift to the Rayleigh wave. To verify the flexibility of this method, several metasurfaces are designed. Numerical results demonstrate that the Rayleigh waves can be focused, split, or converted into evanescent waves by using specific phase gradient configurations. The investigation also suggests the strong potential of metasurface as a smart device for shielding of seismic surface waves.