Finite element analysis of tube drawing process with diameter expansion

This paper presents a tube drawing process with diameter expansion for producing a thin-walled tube effectively. In this proposed process, the tube was flared by a plug pushing into the tube, and then the tube was expanded by drawing the plug in the tube axial direction with chucking the flared tube edge. Optimum plug shape, such as the plug half angle and the corner radius, was investigated by a series of analyses using the finite element method (FEM) for improving the forming limit and the dimension accuracy. At first, a friction coefficient was determined to 0.3 by a comparison of the flaring limit between the analysis and the experiment of the tube flaring. As a result of the analyses in the drawing with the diameter expansion, the forming limit was high when the plug half angle was set to 18~30°. The thickness reduction ratio increased with an increase in the expansion ratio and the plug half angle. In addition, the overshoot, which is a difference between the plug diameter and the tube inner diameter after the drawing, was prevented by using the plug with the corner radius of 20 mm

J1406+0102: Dust Obscured Galaxy Hiding Super Eddington Accretion System with Bright Radio Emission

Recent high-$z$ quasar observations strongly indicate that super-Eddington accretion is a crucial phase to describe the existence of supermassive black holes (SMBHs) with $M_\mathrm{BH} \gtrsim 10^9 M_\odot$ at $z \gtrsim 7$. Motivated by the theoretical suggestion that the super-Eddington phase efficiently produces outflows and jets bright in radio bands, we search and find a super-Eddington radio-loud dust-obscured galaxy (DOG) J1406+0102 at $z=0.236$, through cross-matching of the infrared-bright DOGs of Noboriguchi et al. (2019) with the VLA/FIRST 1.4 GHz radio and the SDSS optical spectral catalog. DOG J1406+0102 shows broad components in the Balmer lines. Assuming those lines are from the broad line region, it gives BH mass estimation of $\log\ (M_\mathrm{BH}/M_\odot)=7.30 \pm 0.25$, and AGN luminosity of $\log (L_\mathrm{bol,[OIII]}/\mathrm{erg}~\mathrm{s}^{-1}) = 45.91\pm0.38$ estimated from the intrinsic [OIII] luminosity, resulting in super-Eddington accretion of $\lambda_\mathrm{Edd}\simeq 3$. We show that 1) DOG J1406+0102 is operating strong AGN feedback: the [OIII] outflow velocity exceeds the escape velocity of the host galaxy halo and the kinetic efficiency is obtained as $\approx$ 8% that can be sufficient to quench the host galaxy, 2) the expected future growth pathway of DOG J1406+0102 would join an over-massive BH trajectory and 3) radio-loud DOGs can provide a significant contribution to the high-energy ($\gtrsim$ 100 TeV) cosmic neutrino background if we assume DOG J1406+0102 as a representative of radio-loud DOGs.Comment: 10 pages, 5 figures, submitted to ApJ

Diel vertical migration of squid in the warm core ring and cold water masses in the transition region of the western North Pacific

We examined the diel vertical migration of squid (dorsal mantle length 21 to 490 mm) in warm core ring (WCR) and cold water mass (CW) areas in the transition region of the western North Pacific. A total of 28 squid species belonging to 23 genera, 2 octopus species from 2 genera, and 1 vampyrmorph Vampyroteuthis infernalis were captured from depths of 20 to 700 m by day and night sampling using a commercial otter trawl. Three patterns of diel vertical migration were recognized for 11 of the squid species. (1) Migrant, in which day and night habitats are clearly separated with peak abundance deeper than 300 m during the day and shallower than 300 m at night: Gonatopsis borealis, Gonatus berryi, Gonatus onyx, Eucleoteuthis luminosa, Onychoteuthis banksii, Enoploteuthis chunii, and Watasenia scintillans. (2) Semi-migrant, in which part of the population migrates to the upper 100 m at night from its daytime habitat of 500 to 600 m, while the remainder of the population mainly remains in the daytime habitat: O. borealijaponica. (3) Non-migrant, in which the habitat is consistently distributed below 400 m: Histioteuthis dofleini, Belonella borealis, and H. inermis. Horizontally, E. luminosa, E. chunii, and H. inermis were restricted to the WCR, while other species were distributed in both the WCR and CW areas in the transition region. Among the vertically migratory and semi-migratory species, nighttime distribution depth was similar between WCR and CW for O. banksii, but was deepened by upper layers of warm subtropical waters in the WCR for G. borealis, G. berryi, W. scintillans, and O. borealijaponica. We also examined day–night habitat temperature ranges for these 11 species

Finite element analysis of tube drawing process with diameter expansion

This paper presents a tube drawing process with diameter expansion for producing a thin-walled tube effectively. In this proposed process, the tube was flared by a plug pushing into the tube, and then the tube was expanded by drawing the plug in the tube axial direction with chucking the flared tube edge. Optimum plug shape, such as the plug half angle and the corner radius, was investigated by a series of analyses using the finite element method (FEM) for improving the forming limit and the dimension accuracy. At first, a friction coefficient was determined to 0.3 by a comparison of the flaring limit between the analysis and the experiment of the tube flaring. As a result of the analyses in the drawing with the diameter expansion, the forming limit was high when the plug half angle was set to 18~30°. The thickness reduction ratio increased with an increase in the expansion ratio and the plug half angle. In addition, the overshoot, which is a difference between the plug diameter and the tube inner diameter after the drawing, was prevented by using the plug with the corner radius of 20 mm

Tube Drawing Process with Diameter Expansion for Effectively Reducing Thickness

The present paper describes a tube drawing method with diameter expansion, which is herein referred to as “expansion drawing”, for effectively producing thin-walled tube. In the proposed method, the tube end is flared by pushing a plug into the tube, and the tube is then expanded by drawing the plug in the axial direction while the flared end is chucked. The forming characteristics and effectiveness of the proposed method were investigated through a series of finite element method (FEM) analyses and experiments. As a result of FEM analysis, the expansion drawing effectively reduced the tube thickness with a smaller axial load when compared with the conventional method. According to the experimental results, the thin-walled tube was produced successfully by the expansion drawing. Maximum thickness reduction ratios for a carbon steel (STKM13C) and an aluminum alloy (AA1070) were 0.15 and 0.29 when the maximum expansion ratios were 0.23 and 0.31, respectively. The above results suggest that the proposed expansion drawing method is effective for producing thin-walled tubes