Papers by Author: Genki Yagawa

Abstract: Almost all the phenomena occurring around us are the coupled phenomena. In the field of numerical analysis, it is difficult to perform coupled analysis. Because, there are a lot of problems and these problems make coupled analysis difficult, so we have to resolve these problems to perform analyses with considering the coupling effect. At present, as the popularity of numerical analysis rising along advancement in computer performance, demand of numerical analyses with incorporating coupling effects will further increase. In this research, we propose a new fluid-structure coupled analysis method using SUPG/PSPG stabilized FEM and Enriched Free Mesh Method to eliminate a lot of problems occurring in the process of coupled analysis. As the feature of our proposed method, linear triangular elements are only used in the analysis.

Abstract: The Enriched Free Mesh Method (EFMM) is a Mixed Method using the Hellinger-Reissner principle. A highly accurate stiffness matrix is computed for each local cluster. As a result, the EFMM can compute the high performance structural problem of low-order mode without an increase in the number of DOF. In this research, a large eigen frequency analysis of discrete model of the EFMM is performed using the Lanczos method on a PC cluster environment.

Abstract: We demonstrate how algorithms to compute hierarchical triangular meshes. We can generate the hierarchical triangular meshes using level-of-detail for the mesh data structure. We perform hierarchical regional partitions using Ward's method with hierarchical data structure to achieve the level-of-detail. The meshes using this data structure can be hierarchically compressed and be unpacked at a faster pace. Additionally, we introduce the adaptive mesh generation algorithms for the parameters of computational mechanics by setting some kind of metrics in the level-of-detail.

Abstract: As an application of probabilistic fracture mechanics (PFM) and a financial method, a risk-benefit model was developed for the purpose of optimizing maintenance activities of steam generator (SG) tubes used in pressurized water reactors (PWRs). To justify whether or not it is worth while implementing the selected maintenance strategy in terms of an economic point of view, net present value (NPV) was calculated as an index which is one of the most fundamental financial indices for decision-making based on the discounted cash flow (DCF) method.