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2 results on '"Zeng, Lujun"'

1. Investigating the Potential of LS 5039 as a Triple System Using Fermi-LAT Data

Author

Zeng, Lujun, Zhang, Mengqing, Ren, Chongyang, Zhang, Pengfei, and Yan, Jingzhi

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

LS 5039 is one of a handful of $\gamma$-ray binary systems in the Milky Way, comprising a pulsar and a massive O-type companion star with an orbital period of 3.9 day. Recently, we conducted a data analysis using approximately 16 year of Fermi-LAT observations, spanning from 2008 August 4 to 2024 July 8. In our timing analysis, we discovered two new periodic signals with frequencies higher and lower than the known orbital period. The higher-frequency signal has a period of 3.63819 day with a 7.1$\sigma$ confidence level, while the lower-frequency signal has a period of 4.21654 day with a 6.3$\sigma$ confidence level. Additionally, in data from the High Energy Stereoscopic System of Cherenkov Telescopes, two potential signals with periods similar to the two newly discovered ones. Considering that these two signals fall within the same frequency interval as the orbital period, we suggest the possibility of a third body orbiting the barycenter of the LS 5039 binary system, with the new periodic signals arising from specific frequency combinations of the two orbital periods., Comment: 7 pages, 5 figures, accepted for publication in ApJ

Published
2024

2. Development and Road Performance Verification of Aggregate Gradation for Large Stone Asphalt Mixture.

Author

Bi, Yufeng, Mu, Minghao, Zeng, Lujun, Ding, Tingting, Qian, Chengduo, Yu, Deshui, and Jiang, Yingjun

Abstract

The pavement base and subbase are the main load-bearing structures of asphalt pavement, and their materials need to have sufficient bearing capacity. Therefore, in the development of LSAM-50 mixtures with higher bearing capacity, after significant research and engineering practice, conventional particle size asphalt mixtures have formed their own excellent mineral gradation and have been incorporated into relevant specifications, while LSAM-50 mixtures, including mineral gradation, have not been involved in related research and engineering applications. According to the strength composition mechanism of asphalt mixtures, under the same circumstances of asphalt, due to the large nominal maximum particle size of LSAM-50 and the small amount of asphalt used, the strength of mineral grading is more important than that of asphalt, which is one of the key issues to be solved in the research of LSAM-50 mixtures. This study aims to enhance the road performance of asphalt mixtures with a maximum nominal particle size of 50 mm (LSAM-50). The variation of void ratios in coarse aggregate skeletons was investigated when aggregates of 37.5–53 mm (designated as D1), 19–37.5 mm (designated as D2), and 9.5–19 mm (designated as D3) were mixed in different proportions. Meanwhile, the effects of fine aggregate gradation on the strength of asphalt mortar and the influence of the ratio of coarse to fine aggregates on the mechanical strength of LSAM-50 were examined. A densely graded structure with strong interlocking for LSAM-50 was proposed, and its road performance was verified. The results indicate that when the ratio of D1, D2, and D3 is 5:2:3, the void ratio of the mixed coarse aggregate is minimized. When the decrement factor i is 0.75, the compressive strength and splitting strength of asphalt mortar reach their maxima. Compared with the densely graded asphalt-stabilized aggregate mixture (ATB-30) with a maximum nominal particle size of 37.5 mm, the dynamic stability of LSAM-50 with the proposed gradation is increased by 400%, the low-temperature bending strain by 3%, the SCB bending strength by 47%, and the residual SCB strength by 90%. [ABSTRACT FROM AUTHOR]

Published
2024
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