In order to improve a vibrational power generator using a magnetostrictive material, i.e., Iron-gallium alloy, and flow-induced vibration of a cantilevered cylinder, a fixed splitter plate was installed behind a cantilevered circular cylinder. Effects of a gap between a splitter plate and a circular cylinder on the performance of the response amplitude, the power of the flow-induced vibrational power generator and the vortex shedding frequency were investigated through wind tunnel experiments. Flow visualizations around a circular cylinder were also conducted by a smoke-wire method using a high-speed camera. The test models had a span length L of 200 mm, 300 mm and 400 mm. The diameter of a circular cylinder D of 40 mm. A splitter plate with a length of 400 mm and a thickness of 2 mm was installed behind the center of the model with a gap G varied from 8 to 104 mm. For a small gap ratio of G/D ≤ 0.6, galloping vibration occurred. From the smoke wire visualization, it was related that the upstream flow to the cylinder went along a side surface of the cylinder and the inner circulatory flow was generated near the gap. As a result, the accelerated gap-flow occurred and the negative pressure was generated periodically on the upper or lower side wall of the cylinder. For a large gap ratio of G/D ≥ 1.2, galloping vibration did not occur, and the response amplitude became similar to the circular cylinder without a splitter plate. The power generation of a circular cylinder having L = 200 mm with G/D = 0.2 was largest. However, the onset wind velocity of vibration was larger than that of the other cylinders and gaps.

The stress propagation for a three-dimensional elastic sphere under a diametric loading condition in the framework of the linear elastodynamics is revisited. By describing displacements in terms of scalar and vector potentials using the Helmholtz theorem, the Navier-Cauchy equation, the time evolution equation for displacements, is converted to the wave equation. The wave equation is Laplace transformed and further solved in spherical coordinates to develop the tabular expressions for displacement and stress in terms of modified spherical Bessel functions, and the coefficients are determined to satisfy the initial and boundary conditions. The obtained solutions are given in the form of an inverse Laplace transform. For the steady solution, the long-time limit of the obtained solutions is derived by using the final value theorem of the Laplace transform. The unsteady solutions are obtained by applying the residue theorem of complex analysis by adding a path with zero contribution in the complex plane. The obtained solution includes longitudinal and transverse waves, and also Rayleigh waves propagating on the surface. The origin of the von Schmidt wave is discussed as a reflected wave produced by the longitudinal wave travelling on the surface. It is also discussed that the wave is bent, unlike in the case of semi-infinite systems.

Since the optimization results obtained by topology optimization depend on the size of the design domain, it is desirable to optimize the design domain as well during topology optimization. In this study, we propose a method to optimize the structural topology for solid structures by topology optimization based on the SIMP (Solid Isotropic Material with Penalization) method, while optimizing the design domain by shape optimization. In other words, we develop a simultaneous optimization method of shape and topology for structures. Under the constraints of volume and equilibrium equations, the compliance as the objective function is minimized. After formulating this design optimization problem, a sensitivity function is derived using the Lagrange multiplier method and adjoint method, which is applied to the H¹ gradient method to determine the optimal shape and topology. The introduction of the H¹ gradient method allows to optimize the shape and topology while simultaneously smoothing the outer shape and obtaining the topology without gray scale and checker board issues and also decreasing the objective function. The effectiveness of the method for topology optimization with the optimized design domain by shape optimization, or the simultaneous design optimization of solid structures is confirmed using numerical examples.

Dry storage of adsorbent reactors after contaminated water treatment in decommissioning contributes to reducing the risk of contamination spread. In general, the drying process of wet particles involves the simultaneous heat and mass transfers in the particle bed, and the thermal flow becomes complicated. In this study, a simulation model considering the physis involved in the bed, such as the structure of the vessel, the distribution of the initial moisture content, and the resistance of heat and mass transfer, was presented. Predictive calculations of the temperature and moisture content in the drying bed in full-diameter vessel were then performed. In addition, the reproductions of the temperature and the amount of evaporation were confirmed by comparison with the actual measurement results. This model was useful for examining heating methods and predicting drying time. Approximately 100 hours after the start of heating, the adsorbent in contact with the inner surface and bottom of the steel container was dried, and it was thought that it is possible to prevent moisture from coming into contact with the container even during long-time storage. Furthermore, by appropriately setting thermal boundary conditions on the top surface of the packed bed, it was able to improve the prediction accuracy of local moisture content.