分类： 天文学 >> 恒星和银河系 提交时间： 2022-04-20
摘要： We report the discovery of a massive protostar M17~MIR embedded in a hot molecular core in M17. The multiwavelength data obtained during 1993--2019 show significant mid-IR (MIR) variations, which can be split into three stages: the decreasing phase during 1993.03--mid-2004, the quiescent phase from mid-2004 to mid-2010, and the rebrightening phase from mid-2010 until now. The variation of the 22\,GHz H2O maser emission, together with the MIR variation, indicates an enhanced disk accretion rate onto M17~MIR during the decreasing and rebrightening phases. Radiative transfer modeling of the spectral energy distributions of M17~MIR in the 2005 epoch (quiescent) and 2017 epoch (accretion outburst) constrains the basic stellar parameters of M17~MIR, which is an intermediate-mass protostar (M~5.4 Msun) with accretion rate ~1.1x10^-5 Msun in the 2005 epoch and ~1.7x10^-3 Msun/yr in the 2017 epoch. The enhanced accretion rate during outburst induces the luminosity outburst L7600Lsun. In the accretion outburst, a larger stellar radius is required to produce accretion rate consistent with the value estimated from the kinematics of water masers. M17 MIR shows two accretion outbursts (t920 yr) with outburst magnitudes of 2 mag, separated by a 6 yr quiescent phase. The accretion outbusrt occupies 83\% of the time over 26 yr. The accretion rate in outburst is variable with amplitude much lower than the contrast between quiescent and outburst phases. The extreme youth of M17 MIR suggests that minor accretion bursts are frequent in the earliest stages of massive star formation.
分类： 信息科学与系统科学 >> 控制科学与技术 分类： 计算机科学 >> 计算机应用技术 提交时间： 2022-04-20
摘要： Process industry is the pillar industry of national economy, particularly, the process of producing magnesia by fused magnesia furnace system is a typical category of process industry. Due to the complex smelting mechanism and changing production factors, abnormal working conditions often occur in fused magnesia furnace. The semi-molten condition is the most typical and harmful abnormal condition. In this paper, an adaptive pretraining-inference-dynamic training-validation semantic segmentation method based on industrial video is proposed for dynamic prediction of semi-molten condition of multiple fused magnesium furnaces. The experimental results show that compared with the prediction model without adaptive learning, the prediction performance of the adaptive learning model in this paper for multiple fused magnesium melting processes is significantly improved.
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