Papers by Keyword: Image Analysis

Abstract: Radiation is essential in medical diagnostics but poses health risks, necessitating effective shielding to minimize exposure. This research evaluates cassava starch-based bioplastic-lead as an alternative radiation shielding material in femur radiography using Anteroposterior (AP) and Lateral projections with portrait and diagonal detector positions. Bioplastic samples with a 45:55 ratio of cassava starch and lead acetate were tested on a preserved human femur with and without shielding. Image processing using the Gaussian High Pass Filter (GHPF) method and analysis with Contrast to Noise Ratio (CNR) and Peak Signal to Noise Ratio (PSNR) were conducted to assess image quality. Results showed that lead bioplastics achieved 49.4% radiation absorption, with optimal anatomical visualization at cut-off frequencies of 5 and 10, while higher frequencies led to image distortions resembling osteoporosis. The best CNR and PSNR values confirmed improved image contrast while maintaining diagnostic accuracy. This research demonstrates that lead bioplastic effectively reduces radiation dose while preserving image quality, making it a promising alternative shielding material for medical imaging applications

Abstract: The lubricant thickness in cold forging was estimated by machine learning of the in situ captured images of the die–workpiece contact interface. The images were in situ captured by a high-speed camera from the backside of the transparent glass die during forging of commercially pure aluminum workpiece. On the other hand, the images of the lubricated workpiece were individually captured as training images for random forest with classification. The classification accuracy of the lubricant thickness was confirmed to be approximately 75% (classification ability: 5–10 μm in lubricant thickness) in the training images with 22,500 px (50 px/mm). The in situ captured images of the die–workpiece contact interface during forging were classified by random forest using the training images. The estimated lubricant thickness of the in situ captured image almost agreed with the lubricant thickness estimated from the mean brightness value of the in situ captured image.

Abstract: Interfacial thermal resistances of Al-Si alloys were evaluated by comparing the measured thermal conductivities and the simulated thermal conductivities. Al-7%Si, Al-18%Si and Al-18%Si held in the solid-liquid coexistence temperature for 90 minutes were fabricated by gravity casting. Thermal conductivities were measured with the steady state thermal conductivity measuring device. Thermal conductivities were also simulated by using optical microscope images. Comparing the measured thermal conductivities and the simulated thermal conductivities, interfacial thermal resistances in Al-Si interfaces were evaluated as about 2.5-4.8×10^-9 m²K/W.

Abstract: The observation, description, and ultimate prediction of causal connections between processing and resulting macroscopic properties stand at the heart of Materials Science and Engineering. To that end, the microstructure is the subject of intense examination, as it is ultimately responsible for the observed emergent behavior. As a result, many of the scientific or technical questions that we strive to answer boil down to quantitatively studying the—sometimes subtle—effects of processing on the microstructure in terms of known or hypothesized thermodynamic and kinetic phenomena. This statement is naturally also true in the case of hot isostatically pressed powder metallurgy tool steels. In the 50 years since the process' popularization, many parameters have been identified as relevant to microstructure formation during consolidation. Among these process variables, the powder solidification structure distribution is probably the last to join the list. Dendritic solidification during the atomization of relatively massive particles produces slightly elongated carbides. On the other hand, cellular solidification in smaller powder particles is responsible for smaller and more angular carbides. Characterizing powder solidification structure as a function of particle size presents two main challenges: First, the assessment relies on examining cross-sections of the powder particles, which are most likely non-diametric. And, second, the manual identification exercise is tedious and highly subjective. In this work, we show how we achieve fast and reliable powder structure solidification distributions using deep learning combined with state-of-the-art stereology reconstruction techniques.

Abstract: X-ray topography (XRT) presents itself as an attractive non-destructive method to replace industry-standard destructive KOH etching used to measure dislocation density. However, a production-line-compatible XRT has to employ a low scan speed in order to work well with automated image analysis, which makes it impractical for a high-volume manufacturing to scan an entire wafer. We introduce the “radial band” approach to sampling the entire wafer’s area with a single-pass 16 mm tall scan band. Such a band spans the entire range of radii and thus captures the typically strong radial dependence of dislocation density over the entire range, while mostly ignoring the typically weak angular dependence of dislocation density and averaging the inevitable noise over the 16 mm band height. The XRT scan time savings for this approach are roughly 15-fold and 20-fold for 150mm and 200mm wafers respectively.

Abstract: Cracking is a typical problem that deteriorates the strength and longevity of a pavement structure. Waste plastic in pavement construction is cost-effective and environmentally friendly. The use of waste plastic has been growing in recent years. Adding waste plastics to the asphalt mixture would improve its physical and mechanical characteristics. As a result, it is a sustainable and long-term solution that helps to reduce plastic waste and preserve the environment. This research aims to develop the image analysis and assess the characteristic of modifying bitumen with different percentages of plastic wastes (0%, 4%, 6%, and 8%). Using blending processes, modified bitumen was prepared. The binder used in this study is penetration grade PEN 60/70. Marshall Test, Indirect Tensile Strength, Resilient Modulus and Dynamic Creep Modulus test were carried out to determine the optimum percentage of waste plastic in asphalt mixture. The modified binders can be used in high-performance asphalt mixtures, as well as to use a well-developed image analysis technique using ImageJ software to characterize asphalt pavement surfaces. The result shows that the modified asphalt mixture is more efficient than the conventional asphalt mixture. Addition of the waste plastic proved sufficient to increase the performance of the asphalt pavement as modified asphalt mixture performance is more stable than conventional mixture.

Abstract: Examination of vascular endothelial function can help infer atherosclerosis progression. This study investigated whether vascular visualization by near-infrared (NIR) light can detect vasodilatation after cuff pressure release of the upper arm and what the correlation is between the brightness decrease ratio (R1) corresponding to vasodilation and the reactive hyperemia index (RHI). We obtained finger vascular images of 53 male subjects by photographing NIR light (wavelength 850 nm) transmitted through the middle phalanx of the middle finger with a charge-coupled device camera. The upper arm was compressed for 10 min using a cuff (200 mmHg), and vascular images before and after cuff compression release were obtained. We analyzed the finger vascular images by NIR light and digital pulse volume using endothelial peripheral arterial tonometry (Endo-PAT). We also calculated the average brightness of each vascular image. Using only the data of the ischemic finger, R1 was defined using the average brightness just before cuff release and the minimum average brightness after cuff release. The brightness of vascular images of the ischemic finger decreased after cuff release probably because of vasodilation. We found significant correlation between R1 and the RHI (r = 0.52; P < 0.001). R1 in the lowest RHI quartile was significantly smaller compared to the highest and second-highest RHI quartiles (P < 0.05). Vascular visualization by NIR light can detect vasodilation after cuff release. This is significantly correlated with the RHI on Endo-PAT.

Abstract: To gain better understanding of rheological transitions from suspension flow to granular deformation and shear cracking, this research conducted shear-deformation on globular semi-solid Al-Cu alloys to study the rheological behavior of semi-solid as a function of solid fraction (38% - 85%) and shear rate (10^-4 – 10^-1 s^-1) under real-time synchrotron radiography observation. By analyzing 17 X-ray imaging datasets, we define three rheological transitions: (i) the critical solid fraction from a suspension to a loosely percolating assembly; (ii) from the net contraction of a loose assembly to the net dilation of a densely packed assembly, and (iii) to shear cracking at high solid fraction and shear rate. Inspired by in-situ observations of semi-solid deformation showing a disordered assembly of percolating crystals in partially-cohesive contact with liquid flow, we reproduced a two-phase sample using the coupled lattice Boltzmann method-discrete element method (LBM-DEM) simulation approach for granular micromechanical modeling. In DEM, each globular Al grain is represented by a discrete element, and the flow of interstitial liquid is solved by LBM. The LBM-DEM simulations show quantitative agreement of semi-solid strain localization with the experiments and are used to explore the components involved in the shear rate dependence of the transitions, and the role of liquid pressure on the initiation of shear cracking.

Abstract: Interfacial thermal resistance of Al-AlN composites was evaluated by comparing the measured thermal conductivity and the simulated thermal conductivity. Al-10vol.%AlN and Al-20vol.%AlN composites were fabricated by spark plasma sintering. Effective thermal conductivity was measured with the steady state thermal conductivity measuring device. Effective thermal conductivity was also simulated by using FE-SEM image and the measured relative density. Comparing the measured thermal conductivity and the simulated thermal conductivity, interfacial thermal resistance in Al-AlN composites was evaluated as about 1.27-6.2510^-9 m²K/W.

Abstract: We have determined different phase fractions from microscopy images using semi-automated image analysis fitting technique, and in addition we have classified each phase according to its hardness. The distribution of grayscale pixels of different phases is first characterised separately for each phase, which are sampled from the microscope image. After this the distributions of the separate phases are fitted to give the corresponding distribution of the whole image. The microhardness measurement provides reliability on the classification of the different phases to ferrite, bainite or martensite. In addition to describing the applied techniques in detail, we present the results obtained from the analysis for one steel subjected to isothermal holding experiments at different temperatures.