Nagasaki Institute of Applied Science Institutional Repository (NiAS)
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Research on User Analysis Methods in the Design of Elderly Assistive Products
Get PDF長崎総合科学大学博士（工学）2025doctoral thesi
PDCA in an arithmetic(mathematics) workshop for elementary and junior high school students―Aiming to improve academic ability in a metaverse environment―
Get PDFAssuming an annual arithmetic (mathematics) workshop for elementary and junior high school students in a metaverse environment, this report represents the initial step of the PDCA cycle for the workshop. The purpose of the workshop is to increase interest in arithmetic (mathematics) and develop logical thinking skills while having fun. To do this, we use arithmetic puzzles called "Mushi-Kui-Zan". As a result, it is expected that students' academic ability in arithmetic (mathematics) will improve.departmental bulletin pape
A Study on Fracture Toughness at Bonded Interface of Stainless-clad Steel Plates for Chemical Takers
Get PDFA few years ago, duplex stainless clad steel plates have been developed and released. They have recently been applied to the cargo tank of chemical tanker, in combination with the duplex stainless clad steel plate (SUS329J3L-clad) and the duplex stainless steel plate (SUS329J3L). For chemical tanker, the cruciform welded joints between the transverse bulkhead and the double bottom in the cargo tank require utmost attention to prevent fatigue crack formation. Therefore, we have conducted various kinds of fracture toughness tests on these duplex stainless clad steel plates (SUS329J3L-clad) as well as the austenitic stainless clad steel plates (SUS316L-clad and SUS317L-clad) to evaluate their fracture toughness at the bonded interface in terms of the safety and reliability.
In this study, we comprehensively organized and evaluated these fracture toughness test results. For the valid Kc value at bonded interface of each stainless clad steel plate, we have obtained the following knowledge points ; it is considered that the valid Kc value is 1.25×103 N/mm3/2 for the austenitic stainless clad steel plates (SUS316L-clad) and it is 1.37×103 N/mm3/2 for the duplex stainless clad steel plates (SUS329J3L-clad), and the duplex stainless clad steel plates (SUS329J3L-clad) showed better fracture toughness than the austenitic stainless clad steel plates (SUS316L-clad and SUS317L-clad).departmental bulletin pape
Proof that the Center of Buoyancy is Equal to the Center of Hydrostatic Pressure ─ Part 3 : Submerged Circular Cylinder and Arbitrary Shaped Submerged Body ─
Get PDFWe recently proved that “ the center of buoyancy is equal to the center of hydrostatic pressure ” for floating bodies. This subject was an unsolved problem in physics and naval architecture, even though the buoyancy taught by Archimedes' principle can be obtained clearly by the surface integral of hydrostatic pressure. Then we thought that the reason why the vertical position of the center of pressure could not be determined was that the horizontal force would be zero due to equilibrium in the upright state.
As a breakthrough, we dared to create the left - right asymmetric pressure field by inclining the floating body with heel angle θ. In that state, the forces and moments due to hydrostatic pressure were calculated correctly with respect to the tilted coordinate system fixed to the body. By doing so, we succeeded in determining the center of pressure. Then, by setting the heel angle θ to zero in order to make it upright state, it could be proved that the center of hydrostatic pressure is equal to the well-known center of buoyancy, i.e., the centroid of the cross - sectional area under the water surface.
As mentioned above, we have already proved this problem for rectangular and arbitrarily shaped cross-sections, and published them on this bulletin of our university in English. Following that, in the 2nd report, separate proofs for a semi - submerged circular cylinder and a triangular prism were also published here. Thus, we have completed the proof for floating bodies, so in this 3rd report, we aim to prove for submerged bodies. We first prove for a submerged circular cylinder, and then apply Gauss's integral theorem to prove it clearly for an arbitrarily shaped submerged body.departmental bulletin pape
Study on the Influence of Amplitude Dependence of SEA parameters for a Single Flat Plate
Get PDFIn this paper, in order to assist in quantitative evaluation when constructing an experimental SEA model, we first conduct the FEM calculations in numerical experiments to determine the large and small damping characteristics of a single flat steel plate structure. Then, using FEM and real experiments, we show the degree of variation in the FRF results and the SEA parameter results at five levels of input force from 1 N to 5 N. As a result, in the case of structure with large damping, it cannot be seen the influence of amplitude dependence of the FRF results. However, the results of the subsystem vibration energy normalized by the input power, which is a SEA parameter, showed the influence of amplitude dependence at relatively small input force. In the case of structures with small damping, the influence of amplitude dependence can be seen in the FRF results. The results of the subsystem vibration energy normalized by the input power showed that the results were more likely to vary due to the spatial averaging process of the number of input and response.departmental bulletin pape
