Digitally focused array ultrasonic testing technique for carbon fiber composite structures
Composite fiber reinforced polymers are highly promising structures. At present, they are widely used in different areas such as aeronautics and nuclear industries. There is a great number of advantages of composite structures such as design flexibility, low cost per cubic inch, resistance to corrosion, lower material costs, lighter weight and improved productivity. However, composites degradation may be caused by different mechanisms such as overload, impact, overheating, creep and fatigue. Comparing to inspection of other materials some unique consideration is required for testing and analysis. Ultrasound testing is the most common method for inspection of composite structures. Digitally Focused Array Technology is considered as novel approach which enables fast and effective quantitative automatic testing. In this study new methodology of quality assurance of composite structure components based on DFA is performed.
Ethological communication permits the exchange of context-specific information among mammals. In recent literature, many investigations have been performed on behavioral responses but little is known about neurophysiological pattern activation. In this study we investigated neuron patterns in response to ultrasound vocalizations, mapping the auditory cortex in order to find the specific activation area which best fits with perceived vocalization in rats. Receptive fields were directly reached through implanted electrodes in order to record the ultrasound information into the auditory system, bypassing sense organs. Techniques based on Principal Component Analysis and statistical analysis were used to investigate the tonotopic organization exploiting local field-potential classifications. The results, according to the sensitivity index, identified two tonotopic fields with a gradient from high-to-low best frequency using unsupervised classification algorithm.