Photoacoustic (PA) imaging techniques have recently attracted much attention and can be used for noninvasive imaging of biological tissues. Most PA imaging systems in research laboratories use the time domain method with expensive nanosecond pulsed lasers that are not affordable for most educational laboratories. Using an intensity modulated light source to excite PA signals is an alternative technique, known as the frequency domain method, with a much lower cost. In this paper, we describe a simple frequency domain PA system and demonstrate its imaging capability. The system provides opportunities not only to observe PA signals in tissue phantoms, but also to acquire hands-on skills in PA signal detection. It also provides opportunities to explore the underlying mechanisms of the PA effect.
The extraction of regions-of-interest (ROIs) in hyperspectral images of breast cancer specimens is currently carried out manually or by visual inspection. In order to address the labor-intensive and time-consuming process of the manual extraction of ROIs in hyperspectral images, an algorithm is developed in this paper to automate the extraction process. This is achieved by using a contrast module and a homogeneity module to duplicate the same manual or visual steps that an expert goes through in order to extract ROIs. The success of the automated process is determined by comparing the classification rates of the automated approach with the manual approach in terms of the ability to separate cancer cases from normal cases.
This work shows the degree of cure achieved after traditional autoclave curing is not completed. Pre‐impregnated, prepreg, based on resin F8552 system was used in the manufacture of various L‐shaped specimens. This system contains carbon tapes as reinforcement structures. Differential scanning calorimetry (DSC) was used in order to obtain quantitative data which support the investigation about the influence of the several factors on L‐shaped composites degree of cure. Approximately 1 year interval was considered in DSC analyses for each sample configuration. The influence of degree of cure has been studied by using symmetric, balanced, and unbalanced laminates with three different thicknesses. The influence of three autoclave cooling rate cycles was also studied. A total 81 samples were used to perform the study. It is observed that the degree of spontaneous residual curing was more significant in thinner samples. The slower cooling rates produce higher degree of cure over time. Last, the degree of residual cure is more pronounced in unbalanced laminates.
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