Method for determining the gas-dynamic characteristics of a nonequilibrium hypersonic flow of nitrogen based on experimental data on the stagnation parameters

A method is developed for determining the pressure, temperature, density, velocity head, Mach number, and other gas-dynamic parameters of a nonequilibrium flow of nitrogen in a hypersonic nozzle. The method is based on experimental data on the stagnation parameters T₀, p₀ and p₀' and the gas-kinetic model adopted for nitrogen.The indices 0 and^* refer to stagnation parameters and the conditions in the minimal cross section of the nozzle, respectively.Translated from Inzhenerno-Fizicheskii Ztarnal, Vol. 56, No. 1, pp. 74–80, January, 1989.     

Testing of models used in the theory of mixtures and applied to calculations of the permittivity of moist wood tissue in the microwave range

The calculated complex permittivity of wood tissue calculated from formulas of the mixture theory at microwave frequencies is analyzed. The permittivity is calculated as a function of temperature, moisture content, density, orientation of fibers with respect to the electric-field vector, and wood type. The experimental data for the dielectric properties of tap water with a determined chemical composition that are measured at a frequency of 915 MHz and high temperatures are presented.     

Analysis of electromagnetic characteristics exhibited by high-power traveling-wave tubes based on a chain of coupled resonators beyond the boundary of the passband of the slow-wave system

The electrodynamic characteristics of a traveling-wave tube (TWT) are numerically and experimentally analyzed beyond the boundary of the transparency band. A high-power three-section TWT with a slow-wave system in the form of a chain of coupled resonators is used as an example to show that, at the low-frequency edge of the operating band, the loaded Q factor of the resonance corresponding to the π-mode oscillations is reduced and that the frequency characteristics do not shift into the low-frequency region.     

Unit for automatic calibration of gas flow rate controllers

A unit is described for automatic calibration of gas flow controllers, within which there is a reference flowmeter device ERU-0.5, making it possible to measure gas working medium flow rates of 0.01–0.5 cm³/sec with a total error of ± (0.3–0.7)%. The operating principle of the construction, a procedure for determining gas mass flow rate, the main parameters of the flow rate device, and measurement errors are considered.     

Scattering characteristics of metal circular wire gratings in microwave and terahertz ranges

Journal of Computational Electronics - This paper presents the results of numerical analysis by the finite element method of metal circular wire gratings illuminated by plane electromagnetic waves...