Damage Evaluation of Reinforced Concrete Columns by Hypervelocity Impact

AbstractTo evaluate local damages of RC columns by the impacts of a high velocity projectile, impact experiments using a gun method were performed for the 1/10 scale RC columns as test specimens. Effects of an amount of main bar and spacing between hoops were examined. Also, scaling effects were evaluated by comparing with the 1/5 and 1/20 scale models, to ensure the effectiveness of the computer simulations. The crater depth and the residual weight of the specimens after the impact were correlated with the kinetic energy of the projectile although an amount of the reinforcement was not affected to the crater depth. The reinforcement by the hoop was effective to suppress the crack propagation to the back surface, but a threshold might exist in the coverage ratio of the hoop. A scaling effect is not observed for the damage of the RC column

First Data Release of the Hyper Suprime-Cam Subaru Strategic Program

The Hyper Suprime-Cam Subaru Strategic Program (HSC-SSP) is a three-layered imaging survey aimed at addressing some of the most outstanding questions in astronomy today, including the nature of dark matter and dark energy. The survey has been awarded 300 nights of observing time at the Subaru Telescope and it started in March 2014. This paper presents the first public data release of HSC-SSP. This release includes data taken in the first 1.7 years of observations (61.5 nights) and each of the Wide, Deep, and UltraDeep layers covers about 108, 26, and 4 square degrees down to depths of i~26.4, ~26.5, and ~27.0 mag, respectively (5sigma for point sources). All the layers are observed in five broad bands (grizy), and the Deep and UltraDeep layers are observed in narrow bands as well. We achieve an impressive image quality of 0.6 arcsec in the i-band in the Wide layer. We show that we achieve 1-2 per cent PSF photometry (rms) both internally and externally (against Pan-STARRS1), and ~10 mas and 40 mas internal and external astrometric accuracy, respectively. Both the calibrated images and catalogs are made available to the community through dedicated user interfaces and database servers. In addition to the pipeline products, we also provide value-added products such as photometric redshifts and a collection of public spectroscopic redshifts. Detailed descriptions of all the data can be found online. The data release website is https://hsc-release.mtk.nao.ac.jp/.Comment: 34 pages, 20 figures, 7 tables, moderate revision, accepted for publication in PAS

The Hyper Suprime-Cam SSP survey: Overview and survey design

Hyper Suprime-Cam (HSC) is a wide-field imaging camera on the prime focus of the 8.2-m Subaru telescope on the summit of Mauna Kea in Hawaii. A team of scientists from Japan, Taiwan, and Princeton University is using HSC to carry out a 300-night multi-band imaging survey of the high-latitude sky. The survey includes three layers: the Wide layer will cover 1400 deg2 in five broad bands (grizy), with a 5 σ point-source depth of r ≈ 26. The Deep layer covers a total of 26 deg2 in four fields, going roughly a magnitude fainter, while the UltraDeep layer goes almost a magnitude fainter still in two pointings of HSC (a total of 3.5 deg2). Here we describe the instrument, the science goals of the survey, and the survey strategy and data processing. This paper serves as an introduction to a special issue of the Publications of the Astronomical Society of Japan, which includes a large number of technical and scientific papers describing results from the early phases of this survey

Fundamental Study for the Relationship between Melt Flow and Spatter in High-Power Laser Welding of Pure Titanium

The objectives of this study is to clarify the rerationship between melt flow and spatters ejected from a molten pool during 10 kW laser welding of a pure titanium plate. Three-dimensional X-ray transmission in-situobservation of the weld molten pool with tungsten carbide tracers revealed that the melt flowed mainly along the bottom of the molten pool from the keyhole tip to the rear part and then from the rear to the front near the surface of the molten pool, while the melt in front of a keyhole flowed upwards along the keyhole wall at a velocity of less than 0.6m/s and then was accelerated to 2.1m/s at the height of about 2 mm above the keyhole inlet. One-way upward melt flows were continuously piled up at the tip of the elongated melt, resulting in spattering as droplets from the molten pool. Moreover, about 80% of spatters were generated from 50-100mm/s to 300 mm/s, the ratio and the size of spatters occurring from the rear part of a keyhole increased from 20% to 80% and became smaller than 1 mm