Kazufumi Uda

Damage produced in laminated plastic plates by small ball collision with the velocity of 50-140 m/s

The sizes of crater and radial cracks produced by small ball collision in specimens prepared by lamination of thin plastic plates were investigated. The sizes increased with increasing ball velocity. The crater depth increased under static-bending stress. A light-mass ball produced a deeper crater than a heavy-mass ball for the same kinetic energy. In the case of static press of a ball on a plate, the circumferential strain around the contact site was changed from compression to tension and a long crack and a few very small cracks were ultimately produced, with increasing pressure. On the other hand, several radial cracks were produced by a collision. Specimen geometry influenced the crack length distribution. The influence of lamination on crack production was investigated for several combinations of laminations using various plate thicknesses. Crack length produced in a specimen supported only at both ends was slightly longer than that in a specimen with complete support.

Prediction and Active Control of Surge Inception in Centrifugal Compressor System without Plenum

Compression systems can be damaged by surges. The maximum efficiency of centrifugal compressors is often achieved at the operating point close to the surge line. Therefore, suppressing surges is essential for industrial applications. We developed a method of predicting and actively controlling surges in compression systems that have an exit plenum, and confirmed its effectiveness experimentally. In this paper, we also describe an early surge prediction and active control method in centrifugal compressor systems without an exit plenum. Our results verified the method’s effectiveness and surge suppression from the initial stage of their occurrence.

Project based learning using natural energy powered small electric vehicle for sustainable technology education

A sustainable education system using electric vehicles is proposed in this paper. University students are able to learn how to use ecological energy sources and the how to design ecological vehicles in step-by-step processes. Three energy sources are considered; sunlight, hydrogen produced from water extracted using sunlight and electrolysis, and bio fuel squeezed from plant seeds. We will explain the three levels of the program to apply to varying skill levels. Students will begin to learn from a basic level.