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Mathematical modeling of dynamical operations of induction motor with external circuits

Syanov A. M., Kosuhina E. S., Polyakov R. M.

Journal of New Technologies in Environmental Science

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2018

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Vol. 2, nr 2

90--97

EN

The development of computers and new numerical mathematical methods greatly expanded the possibility of solving differential equations and the study of electromagnetic and mechanical transients in electromechanical transducers. At same time, new possibilities for solving problems of high complexity and accuracy have appeared. High-speed calculation on a computer allows using field models in mathematical environments with nonlinear and periodic coefficients. Most modern models of solid rotor induction motor (SRIM) are built in nonlinear field environment [1], but without accounting external circuits. In this paper, a mathematical model of the SRIM in the field environment was developed with taking into account external circuits and rotor rotation. This approach enables to control the operating conditions of the induction motor (IM) with the given physical parameters of the external circuitry and thus examine the transients in the IM during the reverse, the failure of one of phases or the change in the frequency of the supply voltage. The field mathematical model of SRIM with external circuits has been developed in the paper. The mathematical model provides to consider the connection of the stator windings. This makes it possible to simulate asymmetric operating modes of the induction motor for incorrect connection of windings and phase failure. Additional resistance connected to the external circuit allows to take into account the resistance of the supply line and its effect on the starting characteristics of the induction motor. The application of switches in the mathematical model enables to research non-simultaneous switching of keys and the effect of the duration of starting break time and reverse of the induction motor.

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Application of instruments of nuclear physics to the calculation of theoretical dose distributions in various organs of the human body for beams used in hadrontherapy

Maliszewska W., Sękowski P., Skwira-Chalot I.

Nukleonika

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2016

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Vol. 61, No. 1

19--22

EN

The area of interests of nuclear physics are studies of reactions, wherein atomic nuclei of projectile collide with target nuclei. An amount of energy lost by projectile nucleus during its passing through the target is a major issue – it is important to know how charged particles interact with matter. It is possible to afford this knowledge by using theoretical programs that calculate energy loss applying the Bethe-Bloch equation. Hadrontherapy, which is a field of still growing interest, is based on the interactions of charged particles with matter. Therefore, there exists a need of creating a simple model that could be used to the calculation of dose distributions in biological matter. Two programs (SRIM, Xeloss), used to the calculation of energy loss by nuclear physicist, have been adapted to determine the dose distributions in analogues of human tissues. Results of the calculations with those programs for beams used in hadrontherapy (e.g. 1H, 12C) will be compared with experimental data available in references.

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Incrustation of alpha-particle emitters in the source backing: influence on activity measurements

Jurado-Vargas M., Fernández-Timón A.

Nukleonika

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2012

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Vol. 57, No. 4

569-573

EN

Alpha particles emitted from radioactive sources are often measured using a 2pi counting geometry in order to determine the activity with a low deviation. The ratio C2pi/A (counting rate/activity) can, however, deviate from the theoretical value of 0.5 because of backscattering in the backing material, scattering and absorption of alpha particles in the source. The experimental counting rates are, therefore, corrected for these effects (backscattering for all sources, plus self-absorption for sources of non-negligible thickness) to determine the real source activity. However, the corrections needed for situations corresponding to alpha-particle sources in which the radionuclides are not deposited but incrusted in the backing material have not been considered. The aim of the present work was therefore to study the influence that incrustation in the backing can have on the total detection efficiency, and hence on the activity estimated for the source. To this end, we used the Monte Carlo computer code SRIM to model the behaviour of the alpha particles in the backing material.