Modern Physics Letters B

A comparative study on the optical, morphological and laser-induced damage characteristics of rubbed polyimide, SiO₂ thin films by glancing angle deposition, and the corresponding liquid crystal (LC) retarders, is presented in this paper. SiO₂ inorganic thin films were prepared with a deposition angle of 45${}^{\circ }$, and traditional polyimide (PI) films were prepared by spin coating and rubbing. The experimental results indicate that the SiO₂ thin films have a good transmittance and resistance to laser damage. The transmittance of the SiO₂ thin films was above 92% in the wavelength range 400–1200 nm, and that of the corresponding LC retarder was approximately 90% in the wavelength range 800–1200 nm. The laser-induced damage threshold of the SiO₂ thin films reached 32.6 J/cm², and that of the corresponding LC retarder was 1.84 J/cm². These results are better than those of the PI alignment films. SiO₂ thin films have potential for use in the LC optical devices for laser applications.

Different from the conventional logistics service network design problem, we design a fast logistics service network based on high-speed railway. An integrative optimization model which is applicable for solving practical problems is established. This paper simultaneously considers three subproblems: Train timetabling, freight flow assignment and electrical multiple units (EMU) routing plan, in which the objectives are simultaneous to minimize the total train travel time, the operation cost and transportation cost of freight transport, the number of freight EMU and the number of maintenance tasks. The constraints imposed in the model include space-time path resource assignment restriction, node operation capability, train safety interval time, train connection time restriction, freight service time window, train loading capacity restriction and EMU routing restriction. Based on the thoughts of divide and conquer, the original problem is decomposed by using the decomposition mechanism of the Lagrange relaxation algorithm to solve the integrated optimization model. To verify the feasibility and effectiveness of the model and algorithm proposed in this paper, a case study is conducted based on Harbin Dalian high-speed railway.

In the research of porous media and the interior of microelectronic devices, fluids frequently shuttle among pores and wall cracks, therefore it is of great significance to explore the influence of media wall on fluid flow and heat transfer. In this paper, CFD-DSMC coupled iterative algorithm is first used in the research of the flow and heat transfer of gas near the wall in the porous media, which simplified into the flow and heat transfer in micron-scale tube with smooth and rough wall conditions. It is found that compared with the pure CFD method, the velocity field obtained by the coupled method is quite different in the region close to the wall, and this will affect the flow field in the mainstream region, that is, with the higher roughness of the wall, the velocity in the central region will be smaller. There is no significant difference in the temperature distribution in the microtube before and after coupling, but the temperature in the mainstream decreases with the increase of the roughness of the wall. In addition, the temperature jump was found from some of the coupling results close to the wall. The results will contribute to a deeper understanding of the influence of rough surfaces on gas flow and heat transfer near the wall, and provide guidance for the regulation of flow and heat transfer in porous media.

A structured carambola-like CoWO₄ was fast prepared by a microwave-assisted hydrothermal method with the help of urea and NH₄F. Physical characterization indicated that the as-obtained CoWO₄ displayed a large specific surface area, high dispersion and self-selected orientation of crystal growth. Further electrochemical tests presented a high specific capacity of 492.0 C⋅g${}^{-1}$ at 1 A⋅g${}^{-1}$, low internal resistance and excellent cycle stability as 137.3% capacity maintenance after 8000 cycles at 20 A⋅g${}^{-1}$. These excellent electrochemical properties for the as-obtained material indicate that CoWO₄ has great potential as hybrid supercapacitor electrode materials. This work also provides a new and effective solution for regulating the morphology of CoWO₄-based hybrid supercapacitor materials to further improve the electrochemical performance.

In this study, we will derive many new diverse performances for the solitary wave solutions to the DNA Peyrard–Bishop Model with Beta-Derivative (DNAPBM) via three distinctive techniques. The first one has profile name: The ($G^{\prime }$/$G)$-expansion method, while the second one has the profile name: the extended direct algebraic method (EDAM) and the third one has the profile name: the Paul-Painlevé approach method (PPAM). The three techniques are implemented in the same vein and are parallel. The agreement between the achieved solitary wave solutions by these suggested three techniques has been shown. The novelty of our results will appear when the comparison is implemented between our obtained solutions and that achieved previously by other authors who applied another technique.

The effects of vacancy defects and torsion on the optoelectronic properties of single-layered 1$T$-TaS₂, including the band structure, electron density difference, defect formation energy and complex dielectric function, are systematically investigated using the first-principles method based on density functional theory (DFT). The results show that vacancy defects cause relaxation of surrounding atoms leading to local distortions in the structure and changes in bond length, and the formation energy of the V${}_S$ system is significantly lower than theV${}_{2S}$ system, which is easier to achieve the single sulfur-atom vacancy in the experiment. The vacancies system successfully opens a narrow bandgap under torsion, where the V${}_S$ system shows a decreasing trend in the range of 2–8${}^{\circ }$, increasing after 10${}^{\circ }$, while V${}_{2S}$ systems keep increasing. Meanwhile, we found that the optical properties of 1$T$-TaS₂ monolayer are closely related to defects and torsion. The results show that the static dielectric constant, the maximum of the imaginary part, initial absorption coefficient and reflectivity of 1$T$-TaS₂ monolayer gradually increases with torsion. The spectra of vacancy systems are all elevated in the low-frequency band, indicating that the vacancy defects have improved the properties of the visible region. The significant decrease after 5 eV indicates that the torsion substantially affects the properties in the UV region.

In this paper, we investigate the nonlinear longitudinal wave equation (LWE) which involves mathematical physics in a magneto-electro-elastic (MEE) circular rod. By three different methods, we found that various forms for exact traveling wave solutions of longitudinal bud equation among an MEE round rod. These new exact and solitary wave solutions are derived in the form of rational, single periodic function, double periodic Jacobian elliptic functions (JEF), especially about Weierstrass elliptic function (WEF). Additionally, certain interesting (3D), (2D) figures represent the LWE provides the corporal information to explain the physically phenomena. By choosing different suitable values of the free parameters, we made some charts and we analyzed these charts to get a lot of valuable information to understand the MEE circular rod. Our work describes the dynamics of the MEE circular rod. Finally, we conclude with some perspectives for our future research work.

Using ab initio first-principles calculations, we investigate the structural, electronic, optical, and vibrational properties of Silver Sulphide Ag₃S and Selenide Ag₃Se with nonlocal hybrids exchange-correlation functional. With our computational predictions, we manage to classify the material to be Fermi-Dirac semi-metal, rather than Weyl metal. Our calculated results show that the electronic band in between the Fermi-Dirac cone shifts downward when we replace the element Sulphide S with Selenide Se. The obtained optical results such as absorption coefficients and dielectric functions (conductivity, reflectivity, etc.) are similar for both Ag₃S and Ag₃Se. A high absorption coefficient of $2\times 10^5$ cm${}^{-1}$ has been reported, and about 50% of light is reflected. In Raman spectra, the A${}_{\mathrm{\text{g}}}^{\mathrm{\text{X}}\text{-}\mathrm{\text{X}}}$ managed to shift downward when replacing the element X, sulphide S with selenide Se, while the A${}_{\mathrm{\text{g}}}^{\mathrm{\text{rigid}}}$ shifts upward (to higher wavelength). The rotation and vibration of the bonding between atoms have also been explained. The calculated results of Silver-VI compounds provide useful information in the exploitation of more complicated structures.