Представлены результаты разработки прибора и бесконтактных электромагнитно-акустических преобразователей, с высокой точностью обеспечивающих измерение скорости и амплитуды стержневой волны в тонких проволоках. Преимуществом прибора является возможность оперативной регулировки коэффициента усиления, центральной частоты амплитудно-частотной характеристики, добротности в широком диапазоне, что необходимо при исследовании сигналов с использованием экспериментальных преобразователей.
ANNOTATIONThe article is about development of 3 mm wave range pulse radar designed for short-range navigation and collision avoidance. The basic technical specifications of the radar are given, and the functional scheme and construction features are described.Belorussian State University of Informatics and Radioelectronics has worked out the 3 mm wave range pulse radar system for short-range navigation and collision avoidance tackling safety problems for small height flights of helicopters and light planes in mountain areas, in urban and industrial building areas, over agriculture lands having high voltage transmission lines; and also solving the problem of highly precise short-range navigation to guide Author's Current Address: V.V. Muravieu. A V . Rubanic and Y.P. Vorobiev, Belorussia" State University Of Informatics and Radioelectronics, 6, P. Brovka Str., Minsk, 220027 Republic of Belarus;, Y.M. Choban and P.V. Fedosuk, Lvov Scientific ResearchRadioengineering Institute, 7, Nauchnaya str., Lvov. 290060 Ukraine. Manuscript
The paper presents noncontact methods for testing the density of thermally expanded graphite (TEG) sheets: acoustic shadow method, based on the evaluation of the transmission coefficient of the acoustic wave in high frequency range, and eddy current method, based on the evaluation of the complex resistance of parametric surface-mounted eddy-current transducer. Rresults of investigation of the sensitivity curves for the sheets and mats of TEG in a wide range of their density variations. According to the results of the experiment, there is a decrease in the amplitude parameter U in the implementation of the acoustic shadow method with an increase in the density of TEG sheets. Increasing the density of TEG sheets also leads to a linear decrease in the complex resistance of eddy current transducer.
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