This study investigates the relationship between void size and insulation lifetime due to partial discharges (PDs) in internal voids. Experimental results clearly show that the larger the void size, the shorter the insulation lifetime, which decreases the lifetime nvalue index of the voltage-time characteristics. The results also show a clear relationship between the insulation lifetime of a solid insulator having void defects and the PD energy generated in the void, which is related to the cumulative PD energy density per cycle. Therefore, we propose estimating the insulation lifetime of an insulator with voids by calculating the cumulative PD energy density per cycle.

No abstract

A structural analysis model including the temporomandibular joint (TMJ), external auditory canal, tympanic membrane, auditory ossicles and cochlea was made. Loads through the TMJ were applied to this model in three-dimensional finite element analysis. It became clear that stress concentration occurred at the lower portion of the external auditory canal, superior tympanic portion (attic), incus long crus, stapes crus and inlet of cochlea. The lower portion of the external auditory canal and attic are favourite sites of cholesteatoma (pearl tumour). Incus long crus and stapes crus are favourite sites of auditory ossicular defects, which are the cause of otitis media. Damage of the cochlea entrance causes high-frequency hearing loss which is age-related.

No abstract

No abstract