To assure the complete long-term stability and safe operation of the large number of Tainter gates used worldwide, the dynamic stability of these gate must be assessed for all operating water levels. The effect of the upstream submergence (upstream water level) on the natural vibration mode of the gate must be carefully examined. When the upstream water level changes, the in-water natural vibration characteristics will change due to the water added mass effect. The natural vibration mode of the skinplate, however, is determined as an inherent vibration characteristic of the gate structure, and the water in contact with the skinplate has the effect of only lowering the natural frequency due to the added mass effect. To assure the accuracy of the stability analysis, the assumption of unchanging vibration mode with changes in the upstream water level must be validated. To do so, this paper presents the test results for a 3-dimensional model gates and for a full-scale operational gate to examine the effect of the upstream water level on the natural vibration mode.

In this study, the equivalent conditions of strength for single lap joint (SLJ) and double lap joint (DLJ) are investigated in terms of the intensity of singular stress field (ISSF) appearing at the interface end. Previous studies showed that the adhesive strength can be expressed as a constant value of critical ISSF independent of the adhesive length and adhesive thickness. In the study, first, the ISSF is investigated under the same load with varying adherend thickness. The minimum ISSF of SLJ can be obtained when the adherend thickness t₁ is large enough. Then, the equivalent conditions of strength for SLJ and DLJ is investigated by changing specimen geometry. The results show that the same strength of the DLJ in JIS (t₁ =1.5mm) can be obtained by using the SLJ with adherend thickness t₁=7mm. Since the deformation of SLJ is large, it is necessary to use the specimen with thicker adherend thickness. When the adherend thickness t₁=25mm, the strength of SLJ is nearly equal to that of DLJ.

Generally speaking, a rotating spindle is supported by at least two rolling bearings. Though the fixing error of the rolling bearing is strictly controlled, it can’t be zero due to the form errors of the elements of a rolling bearing, the difference of dynamic accuracy for the individual rolling bearing, and so on. Therefore, in manufacturing process of a spindle, the rotating accuracy of the spindle is measured with changing the fixing phase of the rolling bearing which supports the spindle. In this process, human intuition and experience have a very important role. When the run-out of the rotating spindle becomes minimum, the attitude of the rolling bearings is fixed. In such a practical technique, the spindle is assembled. In this research, the practical technique, which is not reported in the past, is studied. Consequently, the influence of the fixing phase and the inclination error of the rolling bearing to the non-repetitive run-out (NRRO) of the spindle was clarified quantitatively.