The article discusses a method for detecting defects in extended products. To find defects, scanning the product along its entire length is used. The result is a two-dimensional data stream that needs to be analyzed. The problem of detecting a defect is one of the tasks of detecting a “useful” signal against a background of “noise”. The most reliable method is to use a set of statistical criteria. To compare the mean values, the Student's test and two Wilcoxon–Mann–Whitney tests were used; to compare the scattering values, the Fisher test and the Ansari–Bradley test were used. The effectiveness of the algorithm was confirmed using a computer model simulating a two-dimensional homogeneous data stream.

Keywords: defects, extended products, computer model, simulation, statistical criterion

The article presents studies of a computer simulation statistical model between the characteristics of flows in terms of linear density and the proportion of components in a mixed flow. The results of evaluating the effect of the filling fraction of the component on the average and standard deviation of the fraction of the 1st component in the mixture are presented, the type of autocorrelation functions of the linear density of the mixed stream and the fraction of the 1st component in the mixed stream are determined, estimates of the spectral density of dispersion for the linear density of the mixed stream and the fraction of the 1st component in the mixed stream are shown.

Keywords: fiber mixing, linear density, component fraction, autocorrelation function, spectral density of dispersion, standard deviation

The article discusses a method for detecting local areas with hidden defects in products whose length is several orders of magnitude greater than other dimensions, when processing information from non-destructive testing of the product. To obtain the necessary information, various means of introscopy and radiation of different nature are used. Processing of information obtained using scanning control should detect areas with defects and determine their nature. To compare different processing methods and select the optimal method for processing information, a computer modeling method was used, with the help of which the process of obtaining information and processing it was simulated, which simplifies the selection of the most suitable method for detecting a defect. The article describes typical models of the received signal and presents the simulation results.

Keywords: defects, non-destructive testing, extended products, simulation model, moving averaging, time series

The article considers the process of relaxation of fibrous material after the action of the load on it is completed. A simple model of the relaxation process is constructed in the form of an exponential function, which describes this process quite accurately. It is determined that the relaxation time estimates are robust with respect to the parameter distributions. The constructed relaxation models make it possible to estimate the magnitude of the residual relative strain corresponding to the plastic strain of the material.

Keywords: relaxation, deformation, fibrous material, robustness, Monte Carlo method, exponential model, regression