Перегляд за автором "Meshkov, S."

Зараз показано 1 - 2 з 2
  • Зображення мініатюри
    Публікація
    Application of Thermography to Detect Areas of Water Infiltration in the Dam Concrete Foundation
    (2024) Miahkyi, O.; Meshkov, S.; Orel, R.; Storozhenko, V.
    This paper introduces a methodology devised for thermographic inspection of concrete technical condition inside concrete dams. Water infiltration into a dam accelerates the processes of concrete degradation, so temperature fields provide important information about the dynamics of these processes. As a result of the thermal imaging survey of the observation gallery at a historic hydraulic structure, a formalized pattern of the temperature field inside the dam was acquired and the locations of temperature anomalies associated with infiltration were identified. At the leakage points, the water temperature differed from the concrete temperature by 1.0–2.9 °C, indicating different rates of water flow through the water wall and the gallery ceiling. The temperature of the gallery areas with increased infiltration was 1–2 °C higher than the 12.7 °C selected as the reference temperature. When recording the temperature fields, the optical axis of the thermal imager was directed along the gallery, and not perpendicular to the surfaces under study, as in construction thermography. To this end, a methodological approach was devised to eliminate distortions of the resulting thermograms caused by the curvature of the gallery and other factors. To remove images of extraneous thermal radiation sources from the thermograms and accurately identify the area under study, a method of shielding a part of the image using special masks was used. The comparative thermography method made it possible to eliminate difficulties in determining the emissivity of the gallery concrete surface. The proposed method of comparative thermography made it possible to compare the intensity of filtration processes in the dam body and to link the current state of the hydraulic structure with the history of its restoration. In general, the thermographic method makes it possible to supplement existing primary natural control with a formalized pattern of temperature field inside the dam.
  • Зображення мініатюри
    Публікація
    Reducing the level of interference considering the morphological characteristics of object in thermal nondestructive testing
    (2023) Miahkyi, O.; Storozhenko, V.; Orel, R.; Meshkov, S.
    The interferences characteristic of thermal non-destructive testing that reduces the reliability of the obtained results are described. A methodology for their reduction is proposed, consisting of two interdependent stages. The first stage consists in calculating and analysing the nature and level of the expected signal according to the developed thermophysical model against the background of the experimentally obtained level of interference. According to the results of the analysis of the calculations based on the thermophysical model for the selected samples, the most influential interference was the heterogeneity of the emissivity of the sample surface. The second stage of data processing is devoted to reducing this interference. The second stage consists of processing the thermograms of temperature fields and includes morphological analysis of the surface condition, filtering, and reduction of characteristic interference. It is divided into four practical procedures. Analysis of the visual image and obtaining a map of zones with the different emissivity of the sample surface, analysis of the thermogram with an assessment of the level of discreteness of the thermogram and the position of the reference points on the image, smoothing of the thermographic image and selection of zones with the different emissivity of the surface of the object under control on the thermogram, followed by noise filtering. Since the results of thermal control are strongly influenced by the shape of the object, the capabilities and effectiveness of the proposed methodology are illustrated on a cylindrical object. The experiment confirmed the validity and correctness of the theoretical statements and allowed us to determine the internal structure of the object under study (different wall thicknesses) and reduce the level of structural interference by 3.6 ˚C. The research shows that the processing of experimental data, which was carried out taking into account the specifics of the thermal and structural characteristics of the objects under control, gives a significant positive result and is an important step towards automating thermal non-destructive testing procedures on the way to implementation in current production