Nonlinear Pulse-Time Conversion in Radioisotope Devices: Analysis and Application Possibilities

The paper considers the operation of radioisotope measuring devices under dynamic conditions, when the Poisson pulse flux at the output of the radiation detector becomes unsteady and the nonlinearity of the calibration curve of the device, the stochasticity of the radiation signal and the inertia of the meter significantly complicate the task of estimating the measured physical parameter. of the device and analysis of the possibility of its application for linearization of the characteristics of the device, increasing the speed of the devices and solving the measuring problem in real time.

The process of nonlinear transformation of the radiation signal in the system is analyzed on the basis of the assumption about the exponential distribution of the intervals between the pulses of the information flow at the output of the radiation detector. A generalized algorithm for the synthesis of a given transformation function of a time-pulse computing device of a radioisotope device has been developed according to its mathematical description. To describe the transformation function given by a set of points, it is proposed to use its approximation by a power series.

The proposed calculation formulas are verified by modeling in the Scilab program on a specific example of linearization of the curve of a radioisotope altimeter with a given tabular calibration characteristic. The results obtained confirm the expediency of using time-pulse computing devices for linearizing the conversion curve of radioisotope devices in real time.

Carrying out calculations according to the proposed algorithms by means of modern microelectronics opens up new possibilities for expanding the field of application of radioisotope devices in dynamic problems of industrial flaw detection, measuring the parameters of object movement, thickness of rolled products and coatings, in devices for continuous monitoring of liquid media.

1. Basova E.V., Chasovskikh V.P. Ispol'zovanie radioizotopnykh tolshchinomerov dlya opredeleniya tolshchiny pristenochnykh otlozhenii na vnutrennikh stenkakh tsiklona [Use of radio isotope devices for defining the thickness of adjournment on internal walls of the cyclone]. Fundamental'nye issledovaniya [Fundamental research], 2011, no. 12–4, pp. 760–765.

2. Kuzelev N.R., Egolin Ya.G. Datchiki FGUP «VNIITFA» dlya system kontrolya i upravleniya tekhnologicheskimi protsessami [Fsue "VNIITFA" sensors for monitoringandcontrol systems of technological processes]. Voprosy atomnoi nauki itekhniki. Seriya: Tekhnicheskaya fizika i avtomatizatsiya [Questions of atomic science and technology. Series: Technical Physicsand Automation], Moscow, Nauchno-issledovatel'skii institutetekhnicheskoi fiziki i avtomatizatsii Publ., 2005, pp. 6–11 (in Russian).

3. Bochenin V.I. Radioisotope method for monitoring the level of wear for protective coatings made from chromium and aluminum on gas turbine blades. Measurement Techniques, 2006, vol. 49, no. 10, pp. 1007– 1010. DOI: 10.1007/s11018-006-0227-0

4. Beigzadeh A., Vaziri R., Afaride H. Measurement of temperature dependence of water density using the tool designed gamma densitometer. Iranian Journal of Physics Research, 2019, vol. 19, no. 3, pp. 529–535.

5. Yermakovich O.L., Lisovskiy G.A., Kuchinskiy P.V., Titovitskiy I.A. Povysheniye tochnosti izmereniy radioizotopnogo plotnomera [Increasing the accuracy of radio isotope measurements density]. Pribory i metody izmerenii [Devices and Methods of Measurements], 2015, vol. 1, no. 10, pp. 70–75 (in Russian).

6. Vodovozov A.M. Linearization of the static characteristics of a radioisotope density meter. Measurement Techniques, 2018, vol. 61, pp. 950–954. DOI: 10.1007/s11018-018-1531-1

7. Vodovozov A.M. Digital processing of measurement information in radioisotope devices. Measurement Techniques, 2018, vol. 61, pp. 177–181. DOI: 10.1007/s11018-018-1406-5

8. Sobolev V.I. On the correspondence between dynamic and static errors in data measurement systems. Measurement Techniques, 2014, vol. 57, pp. 247–254. DOI: 10.1007/S11018-014-0440-1

9. Troshchenkov A.I. Teorema Kotel'nikova–Shennona i prakticheskoye ispol'zovaniye tselykh funktsiy dlya predstavleniya signala na priyemnoy storone [Kotelnikov– Shannon theorem and practical use of entire functions for signal representation on the receiving side]. Raketnokosmicheskoye priborostroyeniye i informatsionnyye sistemy [Rocket and Space Instrument Engineering and Information Systems], 2018, vol. 5, iss. 1, pp. 81–85. DOI: 10.30894/issn2409-0239.2018.5.1.81.85

10. Vodovozov А.М. Nonlinear real-time problems in stochastic system with Poisson component. Journal of Instrument Engineering, 2020, vol. 63, no. 6, pp. 501–506 (in Russian).

11. Kingman D. Poisson Processes. Moscow, MTsNMO, 2007.

12. Shynk J.J. Mathematical Foundations for Linear Circuits and Systems in Engineering. Santa Barbara, University of California, 2016.

13. Malykhina G.F., Kislitsyna I.A. Izmerenie parametrov dvizheniya s ispol'zovaniem neironnykh setei [Measurement of motion parameters using neural networks]. Nauchno-tekhnicheskie vedomosti SanktPeterburgskogo gosudarstvennogo politekhnicheskogo universiteta. Informatika. Telekommunikatsii. Upravlenie [Scientific and technical bulletins of the St. Petersburg State Polytechnic University. Informatics. Telecommunications. Control], 2015, no. 5 (229), pp. 59–68. DOI: 10.5862/JCSTCS.229.6

14. Alekseev E.R., Chesnokova O.V., Rudchenko E.A. Scilab: Reshenie inzhenernykh i matematicheskikh zadach [Scilab: Solution of engineering and mathematical problems], Moscow, ALTLinux; BINOM. Laboratoriya znanii, 2008.