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Vol 52, No 3 (2016)
- Year: 2016
- Articles: 9
- URL: https://journal-vniispk.ru/1061-8309/issue/view/11281
Acoustic Methods
Ultrasonic location of inner crack defects in a compound elastic cylinder using an artificial neural-network apparatus
Abstract
The identification of inner defects was performed using ultrasonic control methods and an artificial neural network device. Models of a pipe cross section with an inner ring pad and the propagation of an ultrasonic wave were developed. The influence of different geometric parameters of the studied objects on the indicators of neural-network learning was studied. The optimal structure of a neural network and the form of training vectors for some ultrasonic control methods and their combinations were established.
119-124
Best wavelet basis for wavelet transforms in acoustic emission signals of concrete damage process
Abstract
It is critical to select the best wavelet basis for implementing wavelet algorithms. Firstly, the mathematical characteristics of the eight kinds of wavelet basis commonly used in the field of engineering are summarized and compared based on the analysis of the features of acoustic emission signals from concrete damage process. Secondly, wavelet basis suitable for acoustic emission signals in concrete damage are given by the theoretical analysis. Finally, the best wavelet basis for wavelet transforms in acoustic emission signals of concrete damage process are obtained by calculating the energy entropy. The results show that the energy entropy can be used to select the wavelet basis for acoustic emission signals during the process of concrete damage. Among them, the wavelets of Symlets can be used as the optimum wavelet basis.
125-133
Leak Hunting
On locating a vacuum leak with the indicator fiber particle method
Abstract
A mathematical model is presented for the interaction of a fiber indicator particle with a free molecular gas flow. An inverse problem for locating a leak is formulated and solved using particular trajectories and kinematic characteristics of the indicator’s motion. Diagnostic signs that are sufficient for locating the leak are revealed.
134-140
Radiography
A method for increasing the objectivity of the interpretation of weld radiographs
Abstract
Current radiography-based acceptance criteria do not always guarantee consistency in opinion among experts who are involved in interpretation of radiographs. To improve this consistency, which to a large extent determines the objectivity of the technique, the authors propose classification of radiographic images by shape and appearance in order to simplify weld-defect identification. The acceptance criteria of the RD-25.160.10 KTN-016-15 regulatory document for weld joints in Category 2 oil trunk lines are referred to as an example. The criteria that were developed on the basis of the image classification were used in a statistical experiment that involved six experts. The experiment showed that the number of cases of a substantial degree of consistency of the expert opinions increased by 2.2 times compared to the criteria that are currently in use.
141-145
Hardware for new methods of radiation control
Abstract
Designs of the prototypes of two dosimetry systems that are widely used in the modern international practice of the dosimetry of ionizing radiation, in one of which the ability for real-time measurements of radiation field parameters exists, are presented. The nature of optically stimulated luminescence (OSL) and radioluminescence (RL), on which the operation of the systems is based, is described. The results of tests of prototypes of OSL and RL dosimetry systems are given. Key specifications and advantages over traditional thermoluminescent systems are identified for the Korund-101-OSL OSL system prototype.
146-154
Magnetic and Electromagnetic Methods
A comparative analysis of the active and residual magnetization methods in the nondestructive testing of rails
Abstract
The comparison of residual Magnetic Flux Leakage (MFL) with traditional MFL method was carried out as applied to rail nondestructive testing. The mechanisms for the residual magnetization of rails are considered. It is concluded that the traditional Magnetic Flux Leakage method is more effective as compared with one based on а rail remanence.
155-160
An analytical magnetization model of a layered medium by point poles
Abstract
The case of the magnetization of ferro- and paramagnetic media by point magnetic charges (local poles) is considered. A mathematical model, which can be useful in experimental evaluation of magnetic parameters of layered articles, was obtained.
161-165
Computer-assisted methods for finding pulsed magnetic-field distributions near current-conducting objects
Abstract
Time dependences are given for an electric voltage U(t) that is recorded across an inductive magnetic head when scanning a discontinuous magnetic carrier that has been subjected to pulsed magnetic fields of a linear inductor. The value of U(t) at each point of the carrier is determined by the amplitude of each pulse, the pulse direction, and the sequence of exposures. If a current-conducting object is present, this value also depends on the field pulse rise time. The phenomenon of hysteretic interference of a pulsed magnetic field (HI) is used. Digital images of pulsed magnetic fields, as well as computer-assisted methods for measuring these fields, finding their distributions, and processing observation results are presented.
166-174
Defects detection of gas pipeline near the welds based on self quotient image and discrete cosine transform
Abstract
The magnetic flux leakage (MFL) inspection has been widely used in the inline inspection for the evaluation of steel pipelines and plates. In this paper, a defect detection algorithm based on the MFL inspection is proposed for detecting defects near the welds. The defect in this paper means some deformations and deterioration of steel pipes because of corrosions and cracks by humidity and pressure after gas pipes were buried and it doesn’t mean bad welding. The MFL signal of the defects near the welds is worse than that of the far-away from the welds and has low signal-to-noise ratio (SNR). In this paper, the MFL signal of the defects near the welds is enhanced by using the Self Quotient Image (SQI) in this paper and the position of the defects is detected after applying the Discrete Cosine Transform (DCT). Experiments are conducted to demonstrate the accuracy of the proposed defect detection algorithm for the artificial defects carved on the pipes at the pipeline simulation facility (PSF) and the results show that the proposed algorithm can successfully detect the position of the defects on the pipes near the welds.
175-183