Sayuri Murakami

Acoustic Analysis of Adhesive Surface in Granular Inhomogeneous Structural Material using Neural Network

Difficulty in quality assessment of adhesive interface between granular inhomogeneous materials and a disk plate has been pointed out in nondestructive ultrasonic inspection because of the effect of multiple-reflection at the contact point of each granular particle. A simulation technique is presented in this paper for estimating the adhesion quality of a CBN grinding wheel at the interface between the granular material and the disk plate. The grinding wheel was transposed to one dimensional serial model consisted of each segment of particle with random acoustic impedances at the interface. The propagation of incident ultrasonic waves in the grinding wheel was calculated and echoes from adhesive interface were analyzed. The domestic echo waveform from the adhesive interface was specified and learned by a neural network corresponding adhesion quality and the characteristic of the echo waveform. The effect of the grinding wheel structure to the accuracy of presumption was investigated by using the network. It was revealed that the neural network is effective to assess the adhesive quality of such inhomogeneous structural materials.

Dynamic Response to Mechanical Stimulation in Myobrasts.

Experiment of mechanical stimulus was carried out with myoblast cultured on collagen coated silicone sheet subjected to tension for 6 hours to investigate morphological response of the cell. Pictures of its morphological change were taken in computer by CCD camera in every 10 minutes for 8 hours. Both shape index (SI) and cumulative migration for a lot of cells were measured in every 1 hour. SI was increased after tension exposure. In contrast, migration velocity was decreased after tension exposure. Fluid force acts on cytoskeleton during tension exposure as the shape of cell changes. Actin filament as a cytoskeleton and cytosol were modeled to an elastic cylinder and viscous fluid, respectively, to calculate the stress of filament by the fluid-structure interaction analysis. As a result, the maximum stress was 20 Pa, which is consistent with strain velocity provided by the experiment. Taking into account of its Youngs Modulus, the rupture of filaments does not cause to increase SI of myoblasts.