Current Issue : July - September Volume : 2021 Issue Number : 3 Articles : 3 Articles
The paper presents the use of micro-X-ray computed tomography (CT) system and associated automatic loading device in visualizing and analyzing the propagation of penny-shaped flaw in gypsum-like 3D printing specimen. During the loading process, a micro-X-ray computed tomography (CT) system was used to scan the specimen with a resolution of 30 × 30 μm2. The volumetric images of specimen were reconstructed based on two-dimensional images. Thus, the propagation of penny-shaped flaw in gypsum-like 3D printing specimen in spatial was observed. The device can record the evolution of the internal pennyshaped flaw by X-ray CTscanning and the evolution of the surface crack by digital radiography at the same time. Fractal analysis was employed to quantify the cracking process. Two- and three-dimensional box-counting methods were applied to analyze slice images and volumetric images, respectively. Comparison between fractal dimensions calculated from two- and three-dimensional box-counting method was carried out. The results show that the fractal dimension increases with the propagation of cracks. Moreover, the common approach to obtain the 3D fractal dimension of a self-similar fractal object by adding one to its corresponding 2D fractal dimension is found to be inappropriate....
As an element content analysis technology, X-ray fluorescence spectrometry can be used for quantitative or semiquantitative analysis of the element content in the sample, which is of great significance for mineral census and spent fuel reprocessing. Due to the limitation of the inherent energy resolution of the detector itself, the accuracy of X-ray fluorescence analysis is difficult to be greatly improved. In some applications, even if the semiconductor detector with the best energy resolution is used, the characteristic peaks of different elements cannot be completely separated. ,erefore, greatly improving the energy resolution of the detection system is a hot issue in the existing research field. To solve these problems, this paper analyzes the advantages and disadvantages of the traditional MCA (multichannel analyzer) and SLA (seeds local averaging) algorithm and proposes an ISLA (improved seeds local averaging) algorithm based on mathematical statistics. In the section of theoretical derivation, the principle of ISLA algorithm is described, whose theoretical characteristics and spectral results with different parameters are derived and simulated. In the application effect evaluation, the spectrum obtained by each method is analyzed in detail. Simulation and experimental results show that the spectrum obtained by SLA algorithm has a smaller full width at half maximum than that obtained by MCA, but the seed average process in SLA algorithm also reduces its counting rate. ,e optimized ISLA algorithm can not only effectively reduce the full width at half maximum of the spectral line and sharpen the spectrum peak but also compensate for the loss of the count rate of SLA algorithm....
Asphalt binder film thickness has relation to mixing temperature and binder content in hot mix asphalt, which influences mixture’s performance. A significant variation in assessing the asphalt binder film thickness has been observed in the literature. Development of state of the art technology and Superpave specification requires the study of actual asphalt binder film thickness at micro-level. This study estimates asphalt binder film thickness at micro-level and compares results with those obtained through analytical models from the previous studies. The study utilizes different asphalt mixtures at various mixing temperatures and binder contents. The asphalt binder film thickness around the finest particles of 500nm (0.5 micron) size in asphalt mastic was detected and measured by image analysis (using scanning electron microscope) and elemental analysis (using energy dispersive X-ray spectroscopy) at magnifying power of ×30,000. The analytical estimation revealed that the asphalt binder film thickness for the aforementioned conditions varies from 9 μm to 13 μm, with a fair relationship to binder content and mixing temperature. However, results obtained from image analysis revealed that the asphalt binder film thickness varies from 0.5 μm to 2.4 μm, with no relation to binder content and mixing temperature.Theimage analysis showed that the asphalt mixtures mostly contain asphalt mortar and asphalt mastic, occurring in irregular shape. It was also found that the asphalt binder film does exist as a separate entity inside the asphalt mastic in the form of a band around the filler particles as non-absorbed binder, which fills the approximate distance of 0.5 to 2.5 microns among filler particles....
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