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Application of Visible-near Infrared Spectral Imaging for Monitoring Biological Materials
摘要： N ear infrared (NIR) spectroscopy is a powerful tool for the non-destructive evaluation of biological materials due to its generally weak absorption bands. Biological materials such as wood and plant leaves have a complicated structure in which the distribution of chemical composition and surface structure is non-uniform. Therefore, an imaging technique which combines high spatial resolution with the ability to acquire signal from a wider sample area is required. Three-dimensional image data such as hyperspectral imagery or a movie file has plenty of both spectral and spatial information. However, the visible-near infrared (vis-NIR) spectrum and the time profile of a single pixel normally display strong multicollinearity, thus requiring multivariate analysis for effective extraction of valuable information from three-dimensional image data. This article introduces two examples of image analysis for the non-destructive monitoring of biological materials.
关键词： spectroscopy,multivariate analysis,NIR,imaging,biological materials,hyperspectral,non-destructive evaluation,infrared
更新于2025-09-23 15:23:52
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Enhanced image processing and archiving capabilities of magneto-optical imaging for non-destructive evaluation
摘要： In its current state, the wide acceptance of the Magneto-Optical Imaging (MOI) technique is hindered due to noise, lack of recordable results, and impossibility of data post-processing. This paper presents some add-ons made to a commercial MOI system to ease the image interpretation, archiving and reporting of the results. In addition, a few image processing techniques are also employed in an attempt to perform automatic flaw detection. The recording capability of the MOI instrument output images was addressed by digitizing the video signal in video or image files. To help with the identification of the damage location and distance between images, a rotary quadrature encoder was mounted onto the MOI scan head. The use of the encoder allowed the identification of the inspection location with respect to a reference position, such as the beginning of the scan. Moreover, it allowed saving images at fixed intervals, which were then stitched into a single image, thus simplifying the post inspection analysis process. Both live and post-inspection image processing capabilities were made available. Implemented image processing included background subtraction, de-noising, contrast adjustment and morphological operation, among others. Contrast stretching transform and background subtractions were found to be among the most powerful techniques that could be used in simplifying the image interpretation.
关键词： non-destructive evaluation,Magneto-optical imaging,image processing
更新于2025-09-23 15:23:52
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Non-destructive defect evaluation of polymer composites via thermographic data analysis: A manifold learning method
摘要： Recently, various thermographic data analysis methods have been utilized in the field of non-destructive evaluation (NDE) to process thermal images and enhance the visibility of defects. However, most of them extract only linear features, leading to cumbersome results. In this work, manifold learning is introduced into the thermographic data analysis field. As a nonlinear dimensionality reduction technique, manifold learning can identify an intrinsically low-dimensional manifold in a high-dimensional data space. Specifically, an isometric feature mapping (ISOMAP) based manifold learning thermography (MLT) method is proposed to analyze the thermographic data, which can effectively distinguish the uneven background, noise, and defect characteristics contained in thermal images and make the defect detection easier. The feasibility of MLT is illustrated using a carbon fiber-reinforced polymer (CFRP) specimen. The results show that, comparing to the conventional linear methods, the present method can better determine the defect information, including the positions, sizes, and shapes.
关键词： Thermographic data analysis,Non-destructive evaluation,Manifold learning,Active infrared thermography,Carbon fiber-reinforced polymer
更新于2025-09-23 15:22:29
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Laser-Induced Thermography for Quantitative Detection of Cracks in Building Materials
摘要： Laser-induced thermography is a an active technique using a laser source to heat a very small area on a side of a crack in a building material. The presence of a crack is easily detected as a sharp change in the temperature due to its insulating nature, but no information about its depth is directly available from the thermal image. The method described in this paper uses a heuristic form of the temperature on the surface of the heated specimen, which is transformed to a two-dimensional distribution. Then, a relation is used (called β-tool) between the thermal gap across the crack and the unknown depth of the damage. The purpose is that of making it possible to distinguish between shallow and deep fractures (more than 15mm deep).
关键词： laser-spot thermography,non-destructive evaluation,cracks
更新于2025-09-11 14:15:04
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Local sparseness and image fusion for defect inspection in eddy current pulsed thermography
摘要： Defect feature extraction and analysis based on eddy current pulsed thermography (ECPT) technique is a research focus in non-destructive testing area. In this paper, a new feature extraction method based on thermography is proposed to enhance quantitative defect information. The proposed method included entropy-based image selection, local (element-wise) sparse and low rank decomposition (LSLD) and image fusion can increase the contrast of defect area and background and extract more useful defect features than other two common feature extraction algorithms in ECPT. The experiments including comparison results are provided to demonstrate the capabilities and benefits of the proposed algorithm. More meaningful defect information of the experimental specimens is reserved from raw ECPT data and background is suppressed severely compared with other feature extraction algorithms.
关键词： local sparse,eddy current,image fusion,non-destructive evaluation,thermography
更新于2025-09-11 14:15:04
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Detection of scales and its thickness determination in industrial pipes using Compton backscattering system
摘要： The ability to detect and quantify scales in pipes has been an important yardstick for efficient transfer of fluids in domestic as well as in application related industries. Knowledge of different kinds of scales formed has become a precondition for trouble-shooting in operational lines. In this paper, collimated Compton backscattered gamma rays from a radioactive source have been used to inspect the scales by automatic scanning in steps along the axial direction of different pipes. The methodology has been extended for the quantification of scales that prevails in the real functionality of extensive usage of fluids. To aid for descaling processes, the desideratum is the density determination of scales and this parameter is quantified non-destructively and is also validated with the standard density. The described non-intrusive gamma ray densitometry is quite promising, efficient and has highly reliable results for scale detection with the squared correlation coefficient of 0.98. The proposed technique shows a better linearity than the gammatography technique.
关键词： Compton backscattering,non-destructive evaluation,scale detection,industrial pipes,gamma ray densitometry
更新于2025-09-10 09:29:36
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Quantitative lock-in thermography imaging of thermal-wave spatial profiles and thermophysical property measurements in solids with inner corner geometries using thermal-wave field theory
摘要： In this study, we established a theoretical photothermal model and its experimental validation for an infinitely long solid with an inner corner of arbitrary opening angle, with the solid being irradiated photothermally by a modulated laser beam of arbitrary spatial intensity distribution directed to the corner. The thermal-wave field distribution on the flat surfaces of the solid centered at the corner was obtained using the Green function method. Experimental results based on quantitative thermographic imaging were obtained and used to validate the theoretical model in which thermal diffusivity of an inner cornered stainless steel was measured. The thermal-wave theory based lock-in thermography imaging technique provides a quantitative tool for thermal property measurement and/or non-destructive evaluation of non-flat structures. It also generates valuable physical insights into the spatial distribution of the thermal-wave field in the neighborhood of geometric discontinuities such as inner corners in solids.
关键词： lock-in thermography,thermal-wave field,photothermal model,thermal diffusivity,non-destructive evaluation
更新于2025-09-09 09:28:46
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[IEEE 2018 24th International Conference on Pattern Recognition (ICPR) - Beijing, China (2018.8.20-2018.8.24)] 2018 24th International Conference on Pattern Recognition (ICPR) - Automatic Inspection of Aerospace Welds Using X-Ray Images
摘要： The non-destructive testing (NDT) of components is very important to the aerospace industry. Welds in these components may contain porosities and other defects. These reduce the fatigue life of components and may result in catastrophic accidents if they end up in the aircraft. Currently such welds are inspected by humans studying radiographs of the welds. We describe an automatic system for detecting defects in welds, with the aim of creating a triage system to reduce the workload on human inspectors. Given an X-ray image of the aerospace weld, the system locates the weld line, then analyses the region around the line to identify abnormalities. Our results show that the weld can be precisely extracted from X-ray images and the defect detection operation can identify 83% of defects with fewer than 3 false positives per image, and thus may be useful for prompting human inspectors to reduce their workload.
关键词： weld,NDT,random forests,NDE,defect detection,Non-destructive evaluation/testing
更新于2025-09-04 15:30:14