An electric circuit model describing an inductive sensor of cardiac mechanical activity in its working condition has been developed. The sensor comprises a single-turn coil which is fed by 7.7 MHz constant current and induces probing eddy currents in the body. The inductor is considered to be attached to the thoracic surface of a normal human male, in front of the heart. A simple axial-symmetric model of the thorax, formed of tightly packed circular current tubes, has been used to calculate the resistances, self-inductances and mutual inductances within the human body. Then the inductor and the eddy currents in the body were reduced to a system of two inductively coupled coils; estimates of the parameters and frequency response of the system have been found; the active and reactive contributions of the human body to the resulting impedance of the inductor were calculated.
The objective of this paper is to study a novel method for molten metal circulation in an electric arc furnace. That involves research of operating principles, calculation methods and practical test with a pioneer prototype of the furnace. Construction of the electric arc furnace and new methods for mixing the melting metal in this furnace are described. Principles of constructing arc furnaces are specified. Calculation methods, needed for understanding the operation of the furnace are presented. Emphasis is put on the magnetic field and circulation force density calculation. Modelling of the arc furnace and of the involved processes is carried out. Testing of the pioneer prototype is described and the test results are presented. Evaluation of theoretical calculation methods is done by comparing the results with the practical data.
Abstract. A quasi-analytical method for the solution of direct eddy current testing problems for the case of cylindrical volumetric flaws is presented in the paper. The method is based on a simple physical assumption that the electromagnetic field induced by a coil carrying alternating current is exactly equal to zero at a sufficiently large radial distance from the coil. The axis of the coil concides with the axis of a cylindrical flaw. The method of truncated eigenfunction expansions is used to compute the change in impedance of the coil. Complex eigenvalues are computed numerically using the method which does not require initial approximation for the eigenvalue. Computations are presented for different values of the parameters of the problem. Calculated change in impedance is compared with numerical results obtained by means of Comsol Multiphysics software. Good agreement between quasi-analytical method and numerical solution is found.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.