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111.
Noriyuki Matsunaga † Takahiro Kawadu Shogo Nishiyama † Takahiro Nagayama Hirofumi Hatano † Motohide Tamura Ian S. Glass Tetsuya Nagata 《Monthly notices of the Royal Astronomical Society》2009,399(4):1709-1729
We report the results of a near-infrared survey for long-period variables in a field of view of 20× 30 arcmin2 towards the Galactic Centre (GC). We have detected 1364 variables, of which 348 are identified with those reported in Glass et al. We present a catalogue and photometric measurements for the detected variables and discuss their nature. We also establish a method for the simultaneous estimation of distances and extinctions using the period–luminosity relations for the JHK s bands. Our method is applicable to Miras with periods in the range 100–350 d and mean magnitudes available in two or more filter bands. While J band means are often unavailable for our objects because of the large extinction, we estimated distances and extinctions for 143 Miras whose H - and K s -band mean magnitudes are obtained. We find that most are located at the same distance to within our accuracy. Assuming that the barycentre of these Miras corresponds to the GC, we estimate its distance modulus to be 14.58 ± 0.02 (stat.) ± 0.11 (syst.) mag , corresponding to 8.24 ± 0.08 (stat.) ± 0.42 (syst.) kpc . We have assumed the distance modulus to the Large Magellanic Cloud to be 18.45 mag, and the uncertainty in this quantity is included in the above systematic error. We also discuss the large and highly variable extinction. Its value ranges from 1.5 mag to larger than 4 mag in except towards the thicker dark nebulae and it varies in a complicated way with the line of sight. We have identified mid-infrared counterparts in the Spitzer /IRAC catalogue of Ramírez et al. for most of our variables and find that they follow rather narrow period–luminosity relations in the 3.6–8.0 μm wavelength range. 相似文献
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介绍了简单而又新颖的公式,使用微震的二分量,即圆形台阵记录的水平运动直接推断勒夫波相速度(cL)时,这些公式具有帮助作用。我们的公式与一般用于推断瑞雷波相速度(cR)的微震探测技术的空间自相关(SPAC)方法的公式类似。虽然SPAC方法现有的理论确实提供了估计cL的可能性,但这只能通过求解非线性的方程组才能实现,而其中待求解的未知数也包括cR以及瑞雷波?勒夫波的幂分配比。相反,在我们公式中cL是出现的唯一未知数。基于我们推荐公式——我们称为SPAC+L、SPAC-L和CCA-L(其中CCA表示无中心圆形台阵)法——的cL估算法的现场适用范围通过2个测试点的分析结果说明。在所提出的3种技术中,SPAC+L法由于表现最佳而出名。3种方法的有效波长范围下限是台阵半径r的2~5倍区域,上限是10~25r的区域。近年来,提出了类似的仅涉及cL的圆形台阵微震技术,但与它们相比,我们在此给出的方法,不是在数理计算上繁冗更少,就是在数学上更为简单。 相似文献
115.
Tetsuya?KomabayashiEmail author Kei?Hirose Yasuo?Ohishi 《Physics and Chemistry of Minerals》2012,39(4):329-338
The phase transition boundary between the face-centered cubic (fcc) structure and hexagonal close-packed (hcp) structure in an Fe–Ni alloy was determined at pressures from 25 to 107 GPa by using an internally resistive-heated diamond
anvil cell (DAC), combined with in situ synchrotron X-ray diffraction measurements. The fcc–hcp phase transition boundary in Fe–9.7 wt% Ni is located at slightly lower temperatures than that in pure Fe, confirming the
previous understanding that the addition of Ni expands the stability field of the fcc phase. The dP/dT slope of the boundary was determined to be 0.0426 GPa/K, which is slightly larger than that of pure Fe. The pressure interval
of the two-phase region is about 6 GPa at a constant temperature, implying that the previous estimates by laser-heated DAC
experiments of 10–20 GPa were overestimated. The two-phase region of fcc + hcp would be limited to a pressure of about 120 GPa even in Fe–15 wt%Ni, excluding the possibility of the existence of the fcc phase in the inner core if the simple linear extrapolation of the two-phase region is applied. The pressure and temperature
dependences of the c/a axial ratio of the hcp phase in Fe–9.7 wt% Ni are generally consistent with those in pure Fe, suggesting that Ni has minor effects on the c/a ratio. 相似文献
116.
A hybrid analytical and FEM is proposed to investigate the nonlinear sloshing in a floating‐roofed oil storage tank under long‐period seismic ground motion. The tank is composed of a rigid cylindrical wall and a flat bottom, whereas the floating roof is treated as an elastic plate undergoing large deflection. The contained liquid is assumed to be inviscid and incompressible, and the flow is assumed to be irrotational. The method of analysis is based on representation of the liquid motion by superposing the analytical modes that satisfy the Laplace equation and the rigid wall and bottom boundary conditions. The FEM is then applied to solve the remaining kinematic and dynamic boundary conditions at the moving liquid surface coupled with the nonlinear equation of motion of the floating roof. This requires only the discretization of the liquid surface and the floating roof into finite elements, thus leading to a computationally efficient and accurate method compared with full numerical analysis. As numerical examples to illustrate the applicability of the proposed method, two oil storage tanks with single‐deck type floating roofs damaged during the 2003 Tokachioki earthquake are studied. It is shown that the nonlinear oscillation modes with the circumferential wave numbers 0, 2 and 3 caused by the finite liquid surface elevation as well as the membrane action due to large deflection of the deck produce excessively large stresses in the pontoon, which may cause the catastrophic failure of pontoon followed by the submergence of the roof. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
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Hiroshi A. Takahashi Eiichi Konohira Tetsuya Hiyama Masayo Minami Toshio Nakamura Naohiro Yoshida 《Tellus. Series B, Chemical and physical meteorology》2002,54(2):97-109
Diurnal variation in the atmospheric CO2 concentration and the carbon isotopic composition (Δ14 C and δ13 C) was measured in a forest in an urban area on 9 February 1999. The carbon isotope approach used in the present study differentiated between the quantitative contributions from anthropogenic and biogenic CO2 sources in the urban atmosphere. The anthropogenic (fossil fuel) and biogenic (soil respiration) contributions was estimated, and they ranged from 1 to 16% and from 2 to 8% of the total atmospheric CO2 . The diurnal variation of the anthropogenic CO2 was the major cause of the total atmospheric CO2 variation, while the biogenic CO2 remained relatively constant throughout the day. Estimating the contribution of soil respired CO2 provided the mean residence time of soil respired CO2 within the forest atmosphere. 相似文献
119.
The uneven frost heave of frost-susceptible subgrade soil causes track irregularity, which highly enhances train vibration and affects the comfort and safety of railway transportation. This paper presents a coupled thermo-hydro-mechanical (THM) analysis for the freezing behavior of railway located above a box culvert. The vertical acceleration of the vehicle, an indicator of riding comfort, is predicted through a vehicle dynamic model. The results reveal that the existence of a box culvert changes the subgrade thermal pattern, leading to a deeper frost penetration depth. The frost heave amount above the box culvert is larger than the adjacent section, resulting in uneven track structure upheave and track irregularity. This frost-induced track irregularity highly affects train vibration. 相似文献
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