Using the CST Microwave Studio 2023, models of plasmonic graphene antennas (PGAs) with excitation by using discrete and waveguide ports by incident TEM-waves of S- and P-polarization have been constructed. The characteristics of rectangular and square PGAs with dielectric and metallized substrate: scattering matrix elements, radiation patterns for various graphene parameters and chemical potential values have been calculated.
Computational algorithm for determining the descriptor of autonomous blocks with virtual Floquet channels (MFABs) containing magnetically functionalized carbon nanotubes (MFCNTs) with encapsulated magnetic nanoparticles is developed. The algorithm is based on solving the 3D problem of diffraction for the Maxwell’s equations together with the Landau–Lifshitz equation by applying the Galerkin projection method. Electrodynamic calculation of the complex wavenumbers of the longitudinal and transverse waves propagating in the 3D MFCNT arrays as functions of magnitude of the bias field in the millimeter and terahertz frequency ranges is carried out based on the characteristic equation by means of the developed computational algorithm for calculation of the MFAB conductivity matrix.
The replicated aluminum foam technology implies impregnation of the water-soluble filler (NaCl) with a melt. Products made of replicated aluminum foam have a porosity range of 40–70% and a rather high prime cost; hence, they cannot be commercially competitive as a structural material with an aluminum foam with its porosity of 80–95% and low prime cost. Still, replicated aluminum foam is recognized as an excellent functional material for transferring liquids and gases, and products from it are used as filters. The operational life before cleaning is an important operation parameter of a filtering element. It is determined by porosity, which can be increased using filler multifraction beds. However, to predict the filtering element characteristics, the number of fractions was limited to two, which makes it possible to increase porosity by 10–15%. The size of fine filler fractions was 200–400, 400–630, and 1000–1600 μm in the proportion 30, 50, and 70%, and the coarse fraction was 2500–4000 μm in size. Preparing the filler bed consists in mixing two fractions in a certain proportion and heating up the filler bed in a box resistance furnace with subsequent filling it into a metal mold and pouring with AlSi melt. Impregnation of the filler with the melt was ensured by vacuuming the mold. After crystallization of the casting, it was machined by cutting out a cylindrical sample from the bottom of the composite casting, and then the filler was dissolved in water. The coefficient of permeability of dual-sized replicated aluminum foam was experimentally studied by the nonstationary method. The additive dependence of the permeability coefficient on the proportions and permeability coefficients of monofractions is shown. Permeability coefficients of monofractions are calculated using the model of concentration of single resistances. A review of dual-sized bed permeability models is performed, and it is shown that the Kazemi model is most consistent with the experimental data obtained. A discrepancy with the experiment is evident only at a significant difference of fraction sizes, with a small size of the fine fraction, which is caused by the loosening effect. The obtained results make it possible to design filtering elements with a higher po-rosity.
A mathematical model of microwave heating of the deformation joint of a rigid airfield coating has been presented. The development of the temperature field has been studied numerically on the basis of calculations of the distribution of the electric field intensity generated by the radiation source. The simulation results have been compared and confirmed by experimental data obtained by direct measurements in a specially designed model microwave heating system.
Based on the known differential and integral equations of the balance of forces acting on a spring pendulum, an algorithm for calculating the amplitude of its vibrations is considered when the natural vibration frequency coincides or is close to the vibration frequency of the coerced force of a vibrating centrifugal separator. An example is given how to calculate the vibration amplitude of a vibrating centrifugal separator depending on the spring elasticity coefficient, the vibrating mass, and the resistance of the medium in which the vibrating mass is suspended.
It is assumed that an electric charge moving along a circular path, i.e., with centripetal acceleration, necessarily emits photons. The purpose of this work is to establish the conditions for the radiation of an electric charge proceeding from significant differences between its tangential and centripetal accelerations. Materials and methods. The starting point is a credible statement. A number of mathematically correct transformations are performed with it. Therefore, the result is necessarily reliable. Since electromagnetic radiation carries away energy, the energy of the radiating system changes during radiation. Associated with this is the following well-known rule: change in energy is equal to the work performed. The research results can be used in the construction of theoretical models of phenomena and processes, as well as considered in technical applications.
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