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Establishment of Process of Manufacture of Ti-6Al-4V Alloy Sintering Body by MIM
Otsuka A.,Suzuki K.,Achikita M. 한국분말야금학회 2006 한국분말야금학회 학술대회논문집 Vol.2006 No.1
Ti-6Al-4V has low specific gravity, high corrosion resistance and superior mechanical properties but it is very difficult to control oxygen content in MIM process. It is necessary to use powders with coarse particle size to decrease oxygen content of powders, so feedstocks with poor fluidity and sintered bodies with lower density are obtained in such cases. Fine titanium hydride-dehydride powders were blended with atomized powders to accomplish higher fluidity and sintered density. Sintered bodies had higher sintered density and mechanical properties equivalent to those of wrought materials by controlling oxygen content less than 0.35mass%.
Otsuka I.,Wada K.,Watanabe A.,Kadomura T.,Yagi M. 한국분말야금학회 2006 한국분말야금학회 학술대회논문집 Vol.2006 No.1
Co-based amorphous powder was produced by a new atomization process “Spinning Water Atomization Process (SWAP)”, having rapid super-cooling rate. The composition of the alloys was ((Co0.95Fe0.05)1-xCrx)75Si15B10 (x=0, 0.025, 0.05, 0.075). The powders became the amorphous state even if particle size was up to about 500 μm. The coercive force of powders was about 0.35 - 0.7 Oe. Furthermore, Co-based amorphous powder cores with glass binders were made by cold-pressing and sintering methods. The initial permeability of the core in the frequency range up to 100 kHz was about 110, and the core loss at 100 kHz for Bm = 0.1 T was 350 kW/m3.
Otsuka, Masaaki,Hyung, Siek,Tajitsu, Akito IOP Publishing 2015 The Astrophysical journal Supplement series Vol.217 No.2
<P>We report on an investigation of the extremely metal-poor and C-rich planetary nebula (PN) K648 in M15 using the UV to far-infrared data obtained using Subaru, the Hubble Space Telescope, the Far Ultraviolet Spectroscopic Explorer, Spitzer, and Herschel. We determined the nebular abundances of 10 elements. The enhancement of F ([F/H] = +0.96) is comparable to that of the halo PN BoBn1. The central stellar abundances of seven elements are determined. The stellar C/O ratio is similar to the nebular C/O ratios from recombination lines and from collisionally excited lines (CELs) within error, and the stellar Ne/O ratio is also close to the nebular CEL Ne/O ratio. We found evidence of carbonaceous dust grains and molecules including Class B 6-9 and 11.3 mu m polycyclic aromatic hydrocarbons and the broad 11 mu m feature. The profiles of these bands are similar to those of the C-rich halo PNe H4-1 and BoBn1. Based on the theoretical model, we determined the physical conditions of the gas and dust and their masses, i.e., 0.048 and 4.95 X 10(-7) M-circle dot, respectively. The observed chemical abundances and gas mass are in good agreement with an asymptotic giant branch nucleosynthesis model prediction for stars with an initial 1.25 M-circle dot plus a 2.0 X 10(-3) M-circle dot partial mixing zone (PMZ) and stars with an initial mass of 1.5 M-circle dot without a PMZ. The core mass of the central star is approximately 0.61-0.63 M-circle dot. K648 is therefore likely to have evolved from a progenitor that experienced coalescence or tidal disruption during the early stages of evolution, and became a similar to 1.25-1.5 M-circle dot blue straggler.</P>
DUST AND CHEMICAL ABUNDANCES OF THE SAGITTARIUS DWARF GALAXY PLANETARY NEBULA Hen2-436
Otsuka, Masaaki,Meixner, Margaret,Riebel, David,Hyung, Siek,Tajitsu, Akito,Izumiura, Hideyuki IOP Publishing 2011 The Astrophysical journal Vol.729 No.1
<P>We have estimated elemental abundances of the planetary nebula (PN) Hen2-436 in the Sagittarius (Sgr) spheroidal dwarf galaxy using ESO/VLT FORS2, Magellan/MMIRS, and Spitzer/IRS spectra. We have detected candidates of fluorine [F II] lambda 4790, krypton [Kr III] lambda 6826, and phosphorus [P II] lambda 7875 lines and successfully estimated the abundances of these elements ([F/H] = +1.23, [Kr/H] = +0.26, [P/H] = +0.26) for the first time. These elements are known to be synthesized by the neutron capture process in the He-rich intershell during the thermally pulsing asymptotic giant branch (AGB) phase. We present a relation between C, F, P, and Kr abundances among PNe and C-rich stars. The detections of these elements in Hen2-436 support the idea that F, P, Kr together with C are synthesized in the same layer and brought to the surface by the third dredge-up. We have detected N II and O II optical recombination lines (ORLs) and derived the N2+ and O2+ abundances. The discrepancy between the abundance derived from the oxygen ORL and that derived from the collisionally excited line is > 1 dex. To investigate the status of the central star of the PN, nebula condition, and dust properties, we construct a theoretical spectral energy distribution (SED) model to match the observed SED with Cloudy. By comparing the derived luminosity and temperature of the central star with theoretical evolutionary tracks, we conclude that the initial mass of the progenitor is likely to be similar to 1.5-2.0M(circle dot) and the age is similar to 3000 yr after the AGB phase. The observed elemental abundances of Hen2-436 can be explained by a theoretical nucleosynthesis model with a star of initial mass 2.25 M-circle dot, Z = 0.008, and LMC compositions. We have estimated the dust mass to be 2.9x10(-4) M-circle dot (amorphous carbon only) or 4.0x10(-4) M-circle dot (amorphous carbon and polycyclic aromatic hydrocarbon). Based on the assumption that most of the observed dust is formed during the last two thermal pulses and the dust-to-gas mass ratio is 5.58 x 10(-3), the dust mass-loss rate and the total mass-loss rate are < 3.1x10(-8) M-circle dot yr(-1) and < 5.5x10(-6) M-circle dot yr(-1), respectively. Our estimated dust mass-loss rate is comparable to a Sgr dwarf galaxy AGB star with similar metallicity and luminosity.</P>
Numerical Analysis of Flow in Radial Turbine (Effects of Nozzle Vane Angle on Internal Flow)
OTSUKA, Kenta,KOMATSU, Tomoya,TSUJITA, Hoshio,YAMAGUCHI, Satoshi,YAMAGATA, Akihiro Korean Society for Fluid machinery 2016 International journal of fluid machinery and syste Vol.9 No.2
Variable Geometry System (VGS) is widely applied to the nozzle vane for the radial inflow turbine constituting automotive turbochargers for the purpose of optimizing the power output at each operating condition. In order to improve the performance of radial turbines with VGS, it is necessary to clarify the influences of the setting angle of nozzle vane on the internal flow of radial turbine. However, the experimental measurements are considered to be difficult for the flow in radial turbines because of the small size and the high rotational speed. In the present study, the numerical calculations were carried out for the flow in the radial turbine at three operating conditions by applying the corresponding nozzle vane exit angles, which were set up in the experimental study, as the inlet boundary condition. The numerical results revealed the characteristic flow behaviors at each operating condition.
Atsushi Otsuka,Takahisa Suzuki,Yuto Matsushita,Hiromitsu Watanabe,Keita Tamura,Daisuke Motoyama,Toshiki Ito,Takayuki Sugiyama,Hideaki Miyake 대한배뇨장애요실금학회 2019 International Neurourology Journal Vol.23 No.4
Purpose: To evaluate whether hydrodistention with fulguration of Hunner lesions (HD/FUL) plus maintenance dimethyl sulfoxide (DMSO) therapy prolongs the recurrence-free time in patients with Hunner type interstitial cystitis (IC). Methods: The study enrolled patients with Hunner type IC who required repeat HD/FUL due to recurrence of IC symptoms after the first HD/FUL at our institution. All patients received a second HD/FUL plus maintenance DMSO therapy. The maintenance DMSO therapy was performed every 2 weeks for a total of 8 instillations, and then once every 4 weeks thereafter. The recurrencefree time from HD/FUL to therapeutic failure was estimated using the Kaplan-Meier method. The recurrence-free time between the first HD/FUL and second HD/FUL plus maintenance DMSO therapy was statistically compared using the log-rank test. Results: A total of 21 patients (mean age, 66.3±10.8 years) with Hunner type IC were evaluated. The recurrence-free time for the second HD/FUL plus maintenance DMSO therapy was significantly longer than that for the first HD/FUL (P<0.0001). The median recurrence-free time for the first HD/FUL was 10.1 months, while that for the second HD/FUL plus maintenance DMSO therapy has yet to be reached. The recurrence-free rate for the first HD/FUL was 81.0% at 6 months, 38.1% at 1 year, 9.5% at 2 years, and 4.8% at 3 years. In contrast, the rate for the second HD/FUL plus maintenance DMSO therapy was 100% at 6 months, 94.7% at 1 year, 82.6% at 2 years, and 82.6% at 3 years. There were no significant differences in efficacy between the first and second HD/FUL. Conclusions: HD/FUL plus maintenance DMSO therapy clearly prolongs the recurrence-free time compared with HD/FUL alone in Hunner type IC.