Browsing by Subject "X-rays -- Industrial applications"
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Item Assessment of trash content of cotton using 2D x-ray imagery(Texas Tech University, 2004-08) Dogan, Mehmet SerdarTrash content of raw cotton is a critical quality attribute. Therefore, its assessment is crucial for evaluating its processing and market value. Current technologies, including gravimetric and surface scanning methods, suffer from various limitations. Furthermore, worldwide, the most commonly used method still is human grading. Thus, the need for implementing new technologies is growing. One of the best alternatives to aforementioned approaches is x-ray imaging since it allows a thorough analysis of contaminants in a very precise and quick manner. In other work, we have successfully used x-ray tomographic imaging in the detection and classification of cotton contaminants. In this work, we choose to use x-ray radiographic imaging because of its real-time applicability. The segmentation of trash particles in 2D transmission images is difficult since the background cotton is not uniform. In addition, there is considerable overlap between the gray levels of subtle trash types and dense cotton. We dealt with this problem by characterizing and identifying the background cotton via scale-space filtering followed by a "background normalization" process that removes the background cotton successfully, while leaving the trash particles intact. Furthermore, we have successfully employed stereo x-ray vision for recovering the depth information of the piled trash in controlled samples. While adding to the accuracy with which the trash is counted, this method is much faster than the tomographic approach, as it requires only two projections. We tested our technique on 280 cotton radiographs—graded from 1 to 7 according to its trash content by expert graders—and compared the results with the existing systems of cotton trash evaluation. Results obtained with the proposed method were highly correlated with those obtained using the current systems. Given that the approach described here provides the trash mass in real-time, when realized, it will have a wide-spread usage in the cotton industry.Item Experimental and finite study of armature dynamics in helical magnetic flux compression generators(Texas Tech University, 2002-12) Le, XiaobinArmatures arc the key mechanical component and have significant influence on the performance of helical Magnetic Flux Compression Generators (MFCGs). However, the detailed understanding of the expansion and interaction behavior of armatures with other key mechanical components has neither been well researched nor systematically investigated. The ultimate objective of this dissertation was to systematically investigate the detailed behavior of armatures in helical MFCGs by means of Finite Element Analysis and experimental verification Metallurgical observations on armature samples showed that the microstructural evolution of the material during the armature's expansion process is mainly caused by the rapid circumferential plastic deformation of the material leading lo formation of axial cracks, which first initiate on the expanding armature. The chosen material's constitutive model and equation of state, for input into the finite element models, were verified via explosive experiments. Material models were extensively used to explore the expansion and interaction behavior of armatures in helical MFCGs. The following main conclusions were obtained: 1. There is a serious detonation end effect or "barreling," which might cause an additional magnetic flux loss in an improperly designed helical MFCGs. 2. The expansion angle of the armature in helical MFCGs varies with post-detonation time and with axial positions along the armature. If the armature expansion angle is assumed to be constant, its value should be the average expansion angle measured along the main axis of the armature. 3. There is no scaling effect on the expansion angle of the armature. The expansion angle is only a function of the densities of the armature and the explosive, and the armature's wall thickness ratio. 4 The requirements for armature's expansion behavior are larger expansion angle, small length of detonation end effect and high impact velocity. Based on these requirements, aluminum 6061-T6 armature is the best choice followed by a tri-layer cu-polymer-al design among the five possible armature structures under research. 5. The crowbar's interaction with the armature has a significant local effect on armature, resulting in a larger inward spike on the armature surface and accentuation of the detonation end effect. 6. During the armature's impact with the helical wires/insulators, most of the insulator material is squeezed out of the contact zone. However, some fragments of insulator material can be trapped within the contact zone. 7. The axial shift of the core of the helical wire is not significant and will not result in contact with the core of its adjacent turn. 8. The "turn-skipping" phenomenon is mainly governed by the eccentricity of the armature with the stator, the armature's wall thickness tolerance, the pitch of the helical coils and the armature's expansion angle. The criteria for prevention of "turn-skipping" are presented.Item X-ray microtomographic image analysis for identification of cotton contaminants(Texas Tech University, 2002-08) Pai, Ajay STechnologies currently used for cotton contaminant assessment suffer from some fundamental limitations. These limitations severely restrict the ability of existing technologies to accurately detect and classify contaminants in cotton. Such inaccuracies result in the misassessment of the cotton quality, and have a serious impact on its economic value. The fundamental limitations of existing methods include the inability to detect contaminants under the surface of cotton, the inability to accurately measure shapes and sizes, sample preparation requirements, and poor spatial resolution. These limitations may be easily overcome by the use of x-ray tomographic imaging, which allows for highly accurate imaging of the internal features of an object in a non-destructive fashion. This thesis describes in detail the design of a GUI based interactive cotton contaminant analysis tool. Through the use of an x-ray microtomographic scanner and image processing algorithms, it is shown that x-ray tomographic imaging can provide very accurate information regarding shape, size, and density of cotton contaminants. This information has been analyzed using a fuzzy-logic-based classification scheme to create a highly accurate contaminant analysis tool. Despite its obvious advantages, x-ray imaging does have some drawbacks, principle among which pertains to the time taken to perform the procedure. These drawbacks, along with possible solutions have also been discussed in this thesis. It is our firm belief, however, that if realized in real-time, this procedure will have a definite impact on the cotton cleaning process, and indeed on the economic value of cotton.