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Introduction on Repair of Composites
Published in Mohamed Thariq Hameed Sultan, Murugan Rajesh, Kandasamy Jayakrishna, Repair of Advanced Composites for Aerospace Applications, 2022
M Natesh, A Soundhar, Anita Jessie, V Lakshmi Narayanan
Digital shearography (DISH) is an optical full-field, laser-based and non-destructive method for finding damages in composites. DISH needs a laser source to light the specimen so that a fleck pattern is produced. The fleck pattern is captured through a video image-shearing camera, which concurrently mixes it with a similar but laterally displaced form of itself. The captured images before and after the loading of the application are refined in a computer and a rectification of the images results in a border or edge pattern. The edge or border pattern will comprise of the displacement derivatives of the exterior of specimen (Groves et al. 2007). The fundamental principles of DISH are shown in Figure 6.6. DISH is a contactless method to analyse the flaws in honeycomb sandwich composites for the applications of automobiles (Francis et al. 2010). The merits of the DISH method are rapid detection rate and a simpler device which doesn’t need any additional scanning devices. However, the flaw detection accuracy is based on the depth of the flaw and its size. One disadvantage is that DISH is not appropriate to find the depth of flaw (Hung 1999).
On the Specification of the Information Available for the Perception and Description of the Natural Terrain
Published in Peter Hancock, John Flach, Jeff Caird, Kim Vicente, Local Applications of the Ecological Approach to Human-Machine Systems, 2018
Robert R. Hoffman, Richard J. Pike
The field of remote sensing draws on many specialties and applications to extract information from pictures taken above the Earth’s surface. These include analysis of multispectral satellite images to address issues in environmental science, the study of visible-light aerial photos for civil engineering, and automated cartography and geographic information systems to manipulate spatially based data (Lillesand & Kiefer, 1979). The digital pictures (“images”) that are the common currency of such work usually are analyzed, in part, by machine methods. These computer-generated pictures comprise square-grid matrices of (essentially) context-free atoms called picture elements or pixels. Based on the analysis of pixels, the digital techniques of raster image processing (RIP) can readily distinguish among some types of terrain: water surfaces versus vegetated land, urban, suburban, and rural areas. But despite the many tools—image rectification, spatial filtering, convolution, merging, region segmentation, edge enhancement, Gaussian maximum-likelihood classification, and so on—machine methods of image analysis still find it difficult to consistently distinguish such common features as roads. RIP has indeed met with much success in its efforts to “increase the visual distinctiveness between features in a scene in order to increase the amount of information that can be visually interpreted from the data” (Quattrochi & Pelletier, 1991, p. 10). However, to date, the digital information processing systems cannot outperform the human expert when it comes to perceiving.
Noncontact Dimensional and Profile Metrology by Video Measurement
Published in Toru Yoshizawa, Handbook of Optical Metrology, 2015
Hiroo Tsumuraya, Shuichi Sakai
Image processing technologies have been widely adopted for industrial inspection and measurement applications with the evolution of semiconductor devices since the late 1980s. In the early stage, the image processor units were external hardware processor units and/or frame grabbers for workstations/PCs. Nowadays, thanks to improvement of CPU performance including digital signal processor, camera data transfer protocols, and so on, it is possible to handle the image processing on the application programs running on personal computers. The image processing technologies of the video measuring machines can be classified into the following categories: Edge point detection: input measuring pointsImage rectification: enhancement of edges for easier and stable detectionPattern matching: part alignment, measurement target searchVision AF: AF by image processing
Thermal-Hydraulic Analysis of the LBE Spallation Target Head in JAEA
Published in Nuclear Technology, 2019
As the first step, the stagnant flow regions in the inner tube are expected to be reduced by the target head design. In the original target design, there is only one flow slit beside each edge of the rectification lattice to flow the LBE to cool the irradiation sample holders. However, it is obvious that this configuration leads to the formation of large stagnant flow regions in the inner tube. As a result, the inner tube region cannot be cooled effectively, which leads to the temperature in the stagnant flow regions being over 500°C, which exceeds the criterion of the target design.3 Actually, a recirculation region is formed at the corner area of the inner tube. Because the LBE flow path suddenly expands after the LBE flows from the narrow slits into the inner tube region with a much greater space, the pressure suddenly changes, and flow separation occurs. The large recirculation flow in the inner tube region might impose unstable vibration on the structure, and FAC might occur.