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High-power Test of Annular-ring Coupled Structures for the J-PARC Linac Energy Upgrade
Jun Tamura,Hiroyuki Ao,Yasuo Nemoto,Hiroyuki Asano,Takahiro Suzuki 한국물리학회 2015 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.66 No.3
Annular-ring coupled structures (ACSs) will increase the beam energy of the Japan proton acceleratorresearch complex (J-PARC) linac from 181 to 400 MeV to achieve a beam power of 1MW for a materials and life science experimental facility. The mass production of the ACS cavitiescommenced in March 2009. Before the installation, all cavities require power testing. High-powertesting is essential not only for confirming the cavity’s design performance but also for preventingdelays in cavity conditioning schedule. However, the 2011 Tohoku earthquake damaged J-PARCfacilities, including the ACS power-test area, and cavity conditioning was interrupted for two years. After the facility’s restoration, two ACS cavities (M01 and M11) were conditioned. They performed15 − 20% above the designed accelerating field of 4.2 MV/m. As M01 was initially conditioned sixyears ago, the most recent conditioning time required for M01 was drastically reduced. From thisresult, we confirmed that long-term stored ACS cavities purged with nitrogen gas do not producecritical cavity performance issues. During high-power operation of M11, which is a unique cavityequipped with a capacitive iris in a waveguide, no significant increases in the temperature and thedischarge rate around the capacitive iris were observed. Even considering beam loss due to residualgas scattering, the vacuum pressure was sufficiently low (4 × 10−6 Pa). More stable operation canbe expected following a month-long conditioning process before the beam is commissioned. M11’sconditioning successfully demonstrated an auto-conditioning program, and we established the conditioningscheme using this auto-conditioning program for all ACS cavities in a limited time andwith limited manpower.
Inada, Hiromi,Hirayama, Yoichi,Tamura, Keiji,Terauchi, Daisuke,Namekawa, Ryoji,Shichiji, Takeharu,Sato, Takahiro,Suzuki, Yuya,Ohtsu, Yoshihiro,Watanabe, Keitaro,Konno, Mitsuru,Tanaka, Hiroyuki,Saito, Korean Society of Microscopy 2015 Applied microscopy Vol.45 No.1
We have developed a new HD-2700 (Hitachi High-Technologies Corp., Japan) scanning transmission electron microscope (STEM) that includes an automatic aberration correction function, and a large-solid-angle energy-dispersive X-ray spectroscopy detector that enables high-resolution and sensitive analysis. For observation with atomic resolution, using spherical-aberration-corrected STEM, in order that satisfactory performance of the device can be achieved readily, and within a short time, irrespective of the operator's skill level, a spherical-aberration-correction device with an automatic aberration-correction function was developed. This automatic aberration-correction function carries out the entire correction-related process (aberration measurement, selection and correction) automatically, with automatic selection of the aberrations that require correction, and automatic measurement of the appropriate corrections.
Behavior of R/C cylindrical shell under lateral load
Hara, Takashi,Shigematsu, Tsunemi,Tamura, Takahiro Techno-Press 2003 Structural Engineering and Mechanics, An Int'l Jou Vol.16 No.3
In this paper, the structural behavior of R/C cylindrical panel is analyzed by experimental results. To avoid the geometric imperfection, R/C shell specimens are made by use of a stiff steel mold. From experimental results, the load carrying behavior of R/C cylindrical panel is presented under an external lateral pressure. Even if R/C shell does not posses geometric imperfections, the inaccuracy of the reinforcement position strongly affects to the ultimate strength and the failure patterns of such shells. To explain these effects, FEM nonlinear analyses are done under the same conditions as those of experiments. The behavior of R/C cylindrical shells are well simulated under the consideration of both the geometric imperfection and several inaccuracies.
Nakamae Toshio,Kamei Naosuke,Fujimoto Yoshinori,Yamada Kiyotaka,Tamura Takayuki,Tsuchikawa Yuji,Morisako Taiki,Harada Takahiro,Maruyama Toshiaki,Adachi Nobuo 대한척추외과학회 2022 Asian Spine Journal Vol.16 No.2
Study Design: Cross-sectional study. Purpose: We aimed to quantitatively assess bone marrow edema (BME) on magnetic resonance imaging (MRI) for patients with degenerative lumbar diseases. Overview of Literature: BME adjacent to a sclerotic endplate of the lumbar spine, detected using T2-weighted fat-saturated MRI, is closely associated with low back pain in patients with degenerative lumbar diseases. However, currently, there no quantitative evaluation methods for BME adjacent to the vertebral endplate. Methods: Patients with degenerative lumbar diseases, whose MRIs detected BME, were enrolled. On a T2-weighted fat-saturated MRI, BME appeared as a high-intensity region adjacent to the vertebral endplate. We calculated the contrast ratios (CRs) of BME and normal bone marrow using the signal intensities of BME, normal bone marrow, and the spinal cord. On computed tomography, we calculated Hounsfield unit (HU) values in the same area as BME, the sclerotic endplate, and normal bone marrow to assess bone density. Results: There were 16 men and 14 women, with an average age of 73.5 years. The mean CRs of BME and normal bone marrow were −0.015±0.056 and −0.407±0.023, respectively. BME’s CR was significantly higher than that of normal bone marrow (p<0.01). The HU values in the same area as BME, the sclerotic endplate, and normal bone marrow were 251.9±24.6, 828.3±35.6, and 98.1±9.3, respectively; these values were significantly different from each other (p<0.01). Conclusions: The CR on MRI is a useful quantitative assessment tool for BME in patients with degenerative lumbar diseases.