Katsuhisa Shibukawa

A Refined Theory of Anisotropic Thick Plates

For the deformation of anisotropic plates with arbitrary thickness, a refined theory is proposed to derive approximate equations with any desired accuracy, and general two-dimensional equations in the n-th order approximation are presented. The approximate equations presented are solved for a graphite/epoxy composite plate subjected to a sinusoidally distributed load at the upper surface, and the solutions are compared with the exact one and with those of several other approximate theories by numerical calculation. The results obtained are as follows: (1) The accuracy of solutions of equations in any given order of approximation decreases with increase in the strength of anisotropic property as well as in the plate-thickness. (2) As the order of approximation is increased, the accuracy of solutions is improved and the solutions approach the exact one asymptotically. (3) When the accuracy of solution is appointed for a plate with any thickness and elastic properties, the order of approximation of equations to be used can be determined by preliminary calculation as shown in this paper.

3D Measurement of Shape Using Differential Stereo Vision Alborithm. Enlargement of Depth Range and Improvement of Measurement Accuracy.

In usual 3D measurement of shape by using stereo image, it is necesary to solve a correspondence problem which requires rather complicated image processing and high computational cost. Recently Ando developed the differential stereo vision system in which depth information can be derived from brightness values of image without solving the exact correspondence problem. However, this method has a weak point of narrow depth range in measurement. In this paper, we propose a method to solve a narrow depth range problem and to improve the accuracy of measurement for this method. Several examples of measurement are presented to demonstrate the effectiveness of the proposed method.

Fundamental study on automatic detection and discrimination of surface defects in wood.

There are many types of defects in wood, some of which reduce strength of structure parts or spoil the appearance of furniture parts. To make efficient use of valuable wood free from such defects, it is desired to develop an automated inspection system which is able to locate the position and extent of each defect present and to identify the type of defect at each location. In this paper, we propose an automatic inspection method to detect and discriminate surface defects in wood. The essential points of the method are as follows : Input gray level image of testing wood is divided into a number of regions and several tonal property measures are extracted from image of each region, and fuzzy clustering technique is adopted for detection and discrimination of surface defects. Applying the proposed method to inspection tests of actual lumbers, we obtained the following results : (1) Defect detection can be achieved almost completely. (2) Discrimination rate ranges from 25 to 82% depending on the type of defect, and this indicates that more research is needed.