http://hdl.handle.net/11605/125 2018-9 2026-03-06T14:58:58Z http://hdl.handle.net/11605/127 Title: 一段階溶融塩法による板状NaNbO3 結晶粒の作製 Authors: 石井, 啓介 Abstract: In order to improve the sinterability of textured (K,Na)NbO3 system ceramics, the fabrication method for platelike NaNbO3 single-crystal particles partially substituted with K or Li atoms for Na atoms was studied. The platelike NaNbO3 single-crystal particles obtained by single–step molten salt synthesis in conventional NaCl salt were post-annealed in potassium, lithium, or their mixed salts. The direct synthesis of the single-crystal particles in the mixed salts was also employed without post-annealing. Using the platelike NaNbO3 single-crystal particles partially substituted with K as the templates in reactive template grain growth method, firing period for sintering the textured ceramics was successfully reduced to one sixth. Keywords: Lead-free piezoelectric ceramics, Template grain growth, Single-step molten salt synthesis 2018-08-31T15:00:00Z http://hdl.handle.net/11605/126 Title: 沖縄本島横断時に楕円形へと変形した台風Saomai の眼の解析 Authors: 板野, 稔久 Abstract: The eye of Typhoon Saomai (T0014), distorted into an elliptical shape during its passage over Okinawa Island on 12 Sep. 2000, is analyzed. The typhoon formed double concentric eyewall structure over this period, and it was the inner eye which deformed elliptical. After the deformation, it rotated almost three times with the fixed period of 3 hours from 15:30 JST to 23:30 JST. Then the typhoon lost such a distinctive structure after the entire eye and eyewall entered in the East China Sea. The time-space conversion of the surface meteorological data reveals essentially the same characteristics as what were seen in the other typhoons with elliptical eyes: i.e. the constant rotation rate, the negative pressure anomalies and enhanced rainfall at the longer axis side of the ellipse, etc. Meanwhile, a linear stability analysis based on the asymmetric balance model in log-pressure coordinates shows the wavenumber-2 instability, which theoretically supports the formation of the elliptical eye of typhoon Saomai. Keywords: Typhoon, Tropical cyclone, Elliptical eye, Elliptical eyewall, Asymmetric balance model 2018-08-31T15:00:00Z