Proceedings of IIAE Annual Conference

Mullite (Al₄+2xSi₂-2xO₁₀-x) is a ceramic material with excellent heat resistance and mechanical properties, but its performance can be further enhanced by controlling its crystal orientation. In this study, we focus on the electric field during spark plasma sintering (SPS). Mullite powder (Al₂O₃:SiO₂ = 2:1) was sintered under two conditions: 1400°C (vacuum, 50 MPa) and 1850°C (N₂, 1 MPa, held for 5 min.) X-ray diffraction (XRD) results show that the (001) peak intensity is significantly increased for samples exposed to electric fields, suggesting that dipole The dipole interaction and the local electric field promoted the crystal orientation. These results emphasize the possibility of electric field-assisted orientation of mullite, and future research will focus on optimizing sintering conditions that promote orientation and suppress secondary phases.

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The authors have proposed a child monitoring system capable of estimating four risk conditions during a child’s outing—lingering in dangerous locations, deviating from designated school zones, abduction by vehicle, and immobility in arbitrary places—and notifying the guardian’s device of such conditions. The novelty of the proposed system lies in its foundation on the Crime Opportunity Theory and its ability to quantify the degree of danger at any given location. This enables more flexible condition assessment compared to conventional system. In an experiment conducted using a prototype within an actual school district, the simulated child device successfully inferred all four risk conditions and transmitted the corresponding notifications to the simulated guardian device.

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We developed and prototyped an autonomous underwater vehicle (AUV) designed to stir and aerate residual matter on the seafloor in benthic aquaculture operations. A receiver was mounted on a surface float, enabling remote control via an R/C system. Field tests confirmed that the float successfully tracked the AUV’s movements, allowing stable and flexible navigation at a constant depth.

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Damping materials are essential for achieving precise and stable motion in high-speed robotics. In this study, a magnesium-based composite reinforced with 10 vol% of silicone powder (KMP-602) was developed to improve viscoelastic damping performance. The loss tangent (tanδ), an index representing the ratio of loss stiffness to storage stiffness, was measured using the nanoDMA function of a nanoindenter. The results revealed that tanδ exhibited frequency-dependent behavior. In particular, tanδ showed relatively higher values in the 60–80 Hz range, indicating enhanced energy dissipation within this frequency band. However, the measurements also showed notable variation at the same frequency, with differences reaching up to three to four times across different test points. Several factors likely contributed to this variability. These include incomplete mirror polishing of the sintered specimen surfaces, non-uniform dispersion of KMP-602 particles, and a mismatch between the nanoindenter’s shallow indentation depth (~1 μm) and the relatively large powder sizes used (180 μm for Mg, 30 μm for KMP-602). As a result, the local microstructure had a significant effect on the measurements. Future work will focus on either employing evaluation methods better suited for heterogeneous microstructures or developing composite materials with finer, more uniform structures. These improvements are expected to reduce data variation and lead to a more accurate understanding of the composite’s damping properties.

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