http://elar.nung.edu.ua/handle/123456789/49 The scientific journal 2026-04-05T15:36:30Z http://elar.nung.edu.ua/handle/123456789/115 Title: Pipeline mechanical properties determination using non-destructive method with consideration of microstructural changes Authors: Karpash, M. O.; Dotsenko, Ye. R.; Karpash, O. M. Abstract: Existing pipeline networks used for transportation of oil and gas are being exposed for operation for decades resulting in serious material degradation process occurs in such cases. In this research results of experimental investigation aimed at determination of the electrical resistivity of structural steels used in gas transmission pipelines with the help of the developed experimental unit that implements the four-point method was studied. Multi-parameter approach was utilized in the study while neural networks were used for non-linear approximation of yield strength of pipelines as a function of hardness and electrical resistivity. Samples with special heat-treatment for microstructure distinguishing as well as a number of samples taken from the long-term used pipelines were selected. Destructive tensile testing was performed for all samples under investigation and results were used as references in the study. It was shown that the four-point method can be used to overall metal structures, since the measured value of electrical resistivity does not affect the whole width of the object of control, but only so-called conditional effective width. Under the conditional effective width of the sample should be understood that part of the sample, in which the density of direct current passing through the object, is the largest and which actually affects the measured value of electrical resistivity. Combined measurement of the hardness together with electrical resistivity after neural network processing showed to achieve 26 MPa accuracy for yield strength determination at real-life pipelines. 2014-01-01T00:00:00Z http://elar.nung.edu.ua/handle/123456789/113 Title: Computer system of monitoring and forecasting of water level in rivers Authors: Horbiychuk, M.; Shufnarovych, M. Abstract: Floods and overflow forecasting is a live issue in Ukraine today. There is offered the system of monitoring and forecasting of water levels in rivers to solve this issue. The computer system enables automated acquisition of information about weather conditions and forecasts a future river level. The computer system is based on the method of mathematical models making using genetic algorithms. The use of genetic algorithms ideas for making mathematical models enables us both to choose the optimal structure for an adequate model and to reduce significantly the number of calculations when the models are iterated. The system is implemented for monitoring and forecasting of water levels in rivers of the Precarpathian region. Implementation of an automated system will reduce flood damage and improve efficiency of flood situations management. 2014-01-01T00:00:00Z http://elar.nung.edu.ua/handle/123456789/112 Title: Eguation uncertainty adjustment of the gas flow measurement results flowmeters with standard orifice plates Authors: Lesovoi, L. V.; Fedynets, V. O.; Kuzyk, V. A. Abstract: The analysis of the relative uncertainty of the measurement result equation of gas flowrate. using differential pressure flowmeters with standard orifice plates, defined in GOST 8.586.5-2005 and DSTU COST 8.586.5:2009. is presented. It has been found out that this equation is presented in a simplified form by introducing simplified equations for calculation of relative influence coefficients of input variables upon mass gas flow rate and relative uncertainty of gas expansion factor. New analyticaldependencies for estimation of relative coefficients of influence of differential pressure on orificeplate, of orificeplate hole diameter and measuring pipeline inner diameter on mass gas flow rate. The equation, used to calculate relative uncertainty of gas.expansion factor has been specified. The new equations, used to determine relative influence coefficients of absolute pressure and gas isentropic exponent coefficient on gas expansion factor have been obtained. It has been found out that relative influence coefficients of input variables on mass flow rate of gas and gas expansion factor accept lower values than coefficients of equations, given in Standards. Values of relative influence coefficients obtained from the authors' equations are in good agreement with the results of the calculation of the equations presented in differential form and given in ISO 5168:2005. The analytical dependence reduces relative uncertainty of gas flow rate measurement result. 2014-01-01T00:00:00Z http://elar.nung.edu.ua/handle/123456789/110 Title: The research of gas leak from the pipeline Authors: Grudz, V. Ya.; Grudz, Ya. V.; Drin, N. Ya.; Stasiuk, R. B. Abstract: There are presented the research results of gas leak from the pipeline under pressure through a small hole in a thin wall. The analysis of equations of gas flow energy in the process of gas leak allows making under certain assumptions a formula for the mass flow of gas through a small hole in a wall. However, the experience shows that the assumptions significantly distort the actual state of physical process that ultimately leads to uncertainty in the obtained results. In this regard, there are made a number of analytical and experimental studies to assess the adequacy of theoretical statements with restrictions and the actual results of experiments. The result of the research is an adjustment for the theoretical dependence for the mass flow rate of gas. which Hows through a small hole from the tank. There is also showed the dependence of the adjustment on the pressure and temperature of gas in the tank. 2014-01-01T00:00:00Z