Visual inspection control of pitting defects on the manifold lugs cut out of the gas collection header was performed. This has made it possible to compare and determine the measurement accuracy of previously performed in-line inspections of gas pipelines operated in the presence of the corrosive CO2 in the transported gas. It is determined that the presence of ferromagnetic products of corrosion in local defects negatively affects the measurement of the pipe wall thickness—the local defect depth is 20–30% lower than the real value. After removing corrosion products, it was found that many defects are clusters of corrosion pits combined with each other.

Methods of testing the elasticity of walls of human veins and arteries are considered. The problems that arise when using them are noted. The necessity of developing nondestructive methods for testing the elasticity of the walls of human veins and arteries is substantiated. A technique for monitoring changes in their elasticity using noninvasive methods of pulse wave recording is proposed. The results of comparing data on changes in the elasticity of the walls of veins and arteries obtained using various methods of pulse wave recording and invasive methods are presented. The advantages and disadvantages of the proposed technique using various pulse waves are noted.

Determination and knowledge of the stress-strain state of critical structures and machine parts allows one to take preventive actions. A new approach is proposed to using the laser interferometry method designed to assess residual welding stresses in metal structures. The distinctive feature of this approach is the use of two lasers with different wavelengths simultaneously allowing one to increase the accuracy of the information received. This results in a reduction in the measurement error due to the discreteness of the measurement of residual stresses when counting interference fringes. Improving the measurement accuracy is especially important for cases where the level of residual stresses has relatively small values, for example, post-welding stresses of “light” alloys, shot blasting, and laser surface hardening.

A mathematical model of distortion of the initial radiometric signal by a scintillation detector is proposed for the case of recording continuous X-ray radiation during the formation of digital radiographic images. The model takes into account the distribution of the initial signal over time, the time of radiation registration, the bit depth of the ADC, and the time and amplitude parameters of the fast and slow components of the flashing process in the scintillation detector. An algorithm has been developed for signal reconstruction after a scintillator based on preliminary information about the parameters of a scintillation detector for continuous X-ray radiation. Algorithms for estimating the amplitude and time parameters of the fast and slow components of the flashing process in a scintillation detector for X-ray sources are proposed. A series of computational experiments was carried out and, based on the analysis of its results, the effectiveness of the developed algorithms was demonstrated.

Typical Incremental permeability (IP) requires a high power supply to generate a bias magnetic field that periodically magnetizes the testing samples, making it difficult to apply to occasions where high power supply is short. To solve this problem, this paper presents a low power NDT method based on IP, which is characterized in that the permanent magnets are used to form a bias magnetic field, and the sample is magnetized aperiodically by moving the permanent magnet in one direction. Finite element simulation is used to compare the magnetic fields formed by permanent magnets with different number of blocks and distance between them, as well as the hysteresis curves under magnetic excitation, and a finite element simulation method (FEM) of IP is given. Our experiments used the new method to estimate the yield strength of steels, demonstrating that the proposed method can obtain an approximately accurate result, and its power consumption is less than 2 W.

A new method of fault feature extraction based on the fractional fourier transform variational mode decomposition (FRFT-VMD) method is proposed. First, the core idea of this method is to perform the optimal fractional fourier transform (FRFT) on the original signal. And then the transformed signal is subjected to variational mode decomposition (VMD). Aiming at the problem that the order of FRFT is difficult to determine, a fourth-order central moment (FOCM) method is proposed to determine the optimal order. And use the kurtosis standard deviation criterion (KSDC) to optimize the parameters of VMD. So that FRFT-VMD can be optimized. Finally calculating the kurtosis and impulse factor of the decomposed signal, so as to realize the extraction of fault characteristics. The research results of experimental data show that the signals extracted by this method contain more and more obvious fault characteristic frequencies, which greatly improves the accuracy of fault diagnosis in different states of the bearing normal state, inner ring fault, ball body fault, outer ring fault, etc.

The experimental dependences $$U(t)$$ of electric voltage across a magnetic field transducer on time $$t$$ are presented. The transducer scanned a discrete magnetic field sensor (DMFS) with records of pulsed magnetic fields that passed through aluminum plates with thicknesses of 0.015, 0.05, 0.055, 0.07, 0.09, 0.12, 0.165, 0.225, and 0.26 mm. The DMFS with plates was affected by the magnetic field pulses of a linear complex shaped inductor formed by varying the parameters of the elements of the electric circuit of the source and using delay lines. Hysteresis interference of a pulsed magnetic field in a transmitted wave is obtained for single plates and for plates as part of a massive object making it possible to increase the sensitivity of object thickness gauging by several times compared to hysteresis-free methods and to test objects in narrow gaps between them.

We consider a direct problem of magnetostatics, i.e., calculation of the strength of the resulting magnetic field inside and outside a homogeneous magnet in the form of an arbitrary ellipsoid placed in the region of uniformity of an external magnetic field. The final formulas are given for calculating the indicated strength containing elementary functions or incomplete elliptic integrals. Based on these formulas, formulas for the intensity are obtained for the “limit” cases of a magnet of the indicated shape—a finite thickness plate, an infinite circular cylinder and a cylinder with an elliptical cross section, a ball. A comparison is made with a number of known formulas for these cases.

The impact-echo method, which is a method of free vibrations, is used for testing building structures made of concrete that have the measured thickness H at least six times smaller than the other dimensions and is not used to test compact products in which the thickness H is comparable to the other dimensions. The problem with testing compact objects is that it is impossible to unambiguously determine the required resonant frequency {{f}_{0}}sim {text{1/}}H determined by the product thickness H on the spectrum of the compact product against the background of closely spaced numerous resonances determined by other test object dimensions. Another reason is that due to a strong influence of the geometric dispersion of the sound speed in compact products, it is necessary to calculate a correction factor beta for each new compact test object. The article proposes a solution to the problem of testing compact concrete building structures using a multiplicative impact echo method that allows one to determine the desired resonant frequency, as well as using various versions of the correlation impact echo method that allow one to measure the speed of sound in compact products for the subsequent determination of concrete strength both in the process of cement solidification and during the operation of building structures in order to predict the trouble-free service life of buildings and structures.

Ultrasonic tomographic methods of nondestructive testing of objects have been developed in order to determine the geometry of a weld and to estimate the velocity field in it. A solution to the inverse coefficient problem for the echo signal recording scheme in the shadow-mirror mode is proposed. Numerical simulations have been carried out for various tomographic schemes on samples with acoustic parameters and a geometry corresponding to a real experiment using an antenna array with an operating frequency of 2.25 MHz. Optimization of tomographic schemes for various applied problems is carried out by numerical methods. It is shown that with the help of the developed tomographic schemes it is possible not only to detect the boundaries of a welded joint, but also to determine the velocity field inside the test object.