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2,511 results on '"Li, Yajun"'

1. Polarization Perspectives on Hercules X-1: Further Constraining the Geometry

Author

Zhao, Qingchang, Li, Hancheng, Tao, Lian, Feng, Hua, Zhang, Shuangnan, Walter, Roland, Ge, Mingyu, Tong, Hao, Ji, Long, Zhang, Liang, Qu, Jinlu, Huang, Yue, Ma, Xiang, Zhang, Shu, Yin, Qianqing, Yin, Hongxing, Ma, Ruican, Zhao, Shujie, Li, Panping, Yang, Zixu, Liu, Hexin, Yu, Wei, Huang, Yiming, Li, Zexi, Li, Yajun, Xiao, Jingyu, and Zhao, Kang

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

We conduct a comprehensive analysis of the accreting X-ray pulsar, Hercules X-1, utilizing data from IXPE and NuSTAR. IXPE performed five observations of Her X-1, consisting of three in the Main-on state and two in the Short-on state. Our time-resolved analysis uncovers the linear correlations between the flux and polarization degree as well as the pulse fraction and polarization degree. Geometry parameters are rigorously constrained by fitting the phase-resolved modulations of Cyclotron Resonance Scattering Feature and polarization angle with a simple dipole model and Rotating Vector Model respectively, yielding roughly consistent results. The changes of $\chi_{\rm p}$ (the position angle of the pulsar's spin axis on the plane of the sky) between different Main-on observations suggest the possible forced precession of the neutron star crust. Furthermore, a linear association between the energy of Cyclotron Resonance Scattering Feature and polarization angle implies the prevalence of a dominant dipole magnetic field, and their phase-resolved modulations likely arise from viewing angle effects., Comment: Accepted for MNRAS

Published
2024

2. Simulation Studies for the First Pathfinder of the CATCH Space Mission

Author

Huang, Yiming, Zhang, Juan, Tao, Lian, Li, Zhengwei, Zhao, Donghua, Yin, Qian-Qing, Wen, Xiangyang, Xiao, Jingyu, Zhang, Chen, Zhang, Shuang-Nan, Xiong, Shaolin, Bu, Qingcui, Cang, Jirong, Cao, Dezhi, Chen, Wen, Ding, Siran, Gao, Min, Gao, Yang, Hou, Shujin, Jia, Liping, Jin, Ge, Li, Dalin, Li, Jinsong, Li, Panping, Li, Yajun, Liu, Xiaojing, Ma, Ruican, Pan, Xingyu, Qi, Liqiang, Rao, Jinhui, Sun, Xianfei, Tang, Qingwen, Tang, Ruijing, Wang, Yusa, Xu, Yibo, Yang, Sheng, Yang, Yanji, Yang, Yong, Zhang, Xuan, Zhang, Yueting, Zhou, Heng, Zhao, Kang, Zhao, Qingchang, Zhao, Shujie, and Zhao, Zijian

Subjects
Astrophysics - Instrumentation and Methods for Astrophysics
Abstract

The Chasing All Transients Constellation Hunters (CATCH) space mission is an intelligent constellation consisting of 126 micro-satellites in three types (A, B, and C), designed for X-ray observation with the objective of studying the dynamic universe. Currently, we are actively developing the first Pathfinder (CATCH-1) for the CATCH mission, specifically for type-A satellites. CATCH-1 is equipped with Micro Pore Optics (MPO) and a 4-pixel Silicon Drift Detector (SDD) array. To assess its scientific performance, including the effective area of the optical system, on-orbit background, and telescope sensitivity, we employ the Monte Carlo software Geant4 for simulation in this study. The MPO optics exhibit an effective area of $41$ cm$^2$ at the focal spot for 1 keV X-rays, while the entire telescope system achieves an effective area of $29$ cm$^2$ at 1 keV when taking into account the SDD detector's detection efficiency. The primary contribution to the background is found to be from the Cosmic X-ray Background. Assuming a 625 km orbit with an inclination of $29^\circ$, the total background for CATCH-1 is estimated to be $8.13\times10^{-2}$ counts s$^{-1}$ in the energy range of 0.5--4 keV. Based on the background within the central detector and assuming a Crab-like source spectrum, the estimated ideal sensitivity could achieve $1.9\times10^{-12}$ erg cm$^{-2}$ s$^{-1}$ for an exposure of 10$^4$ s in the energy band of 0.5--4 keV. Furthermore, after simulating the background caused by low-energy charged particles near the geomagnetic equator, we have determined that there is no need to install a magnetic deflector.

Published
2024
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8. In-orbit background simulation of a type-B CATCH satellite

Author

Xiao, Jingyu, Qi, Liqiang, Zhang, Shuang-Nan, Tao, Lian, Li, Zhengwei, Zhang, Juan, Wen, Xiangyang, Yin, Qian-Qing, Yang, Yanji, Bu, Qingcui, Yang, Sheng, Liu, Xiaojing, Huang, Yiming, Chen, Wen, Yang, Yong, Liu, Huaqiu, Xu, Yibo, Zhao, Shujie, Zhang, Xuan, Li, Panping, Zhao, Kang, Ma, Ruican, Zhao, Qingchang, Tang, Ruijing, Rao, Jinhui, and Li, Yajun

Subjects
Astrophysics - Instrumentation and Methods for Astrophysics, High Energy Physics - Experiment
Abstract

The Chasing All Transients Constellation Hunters (CATCH) space mission plans to launch three types of micro-satellites (A, B, and C). The type-B CATCH satellites are dedicated to locating transients and detecting their time-dependent energy spectra. A type-B satellite is equipped with lightweight Wolter-I X-ray optics and an array of position-sensitive multi-pixel Silicon Drift Detectors. To optimize the scientific payloads for operating properly in orbit and performing the observations with high sensitivities, this work performs an in-orbit background simulation of a type-B CATCH satellite using the Geant4 toolkit. It shows that the persistent background is dominated by the cosmic X-ray diffuse background and the cosmic-ray protons. The dynamic background is also estimated considering trapped charged particles in the radiation belts and low-energy charged particles near the geomagnetic equator, which is dominated by the incident electrons outside the aperture. The simulated persistent background within the focal spot is used to estimate the observation sensitivity, i.e. 4.22$\times$10$^{-13}$ erg cm$^{-2}$ s$^{-1}$ with an exposure of 10$^{4}$ s and a Crab-like source spectrum, which can be utilized further to optimize the shielding design. The simulated in-orbit background also suggests that the magnetic diverter just underneath the optics may be unnecessary in this kind of micro-satellites, because the dynamic background induced by charged particles outside the aperture is around 3 orders of magnitude larger than that inside the aperture., Comment: 24 pages, 13 figures, 7 tables, accepted for publication in Experimental Astronomy

Published
2023
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9. Lightweight Multimodal Fusion for Autonomous Navigation via Deep Reinforcement Learning

Author

Li, Yajun, Wei, Changyun, Xia, Yu, Angrisani, Leopoldo, Series Editor, Arteaga, Marco, Series Editor, Chakraborty, Samarjit, Series Editor, Chen, Jiming, Series Editor, Chen, Shanben, Series Editor, Chen, Tan Kay, Series Editor, Dillmann, Rüdiger, Series Editor, Duan, Haibin, Series Editor, Ferrari, Gianluigi, Series Editor, Ferre, Manuel, Series Editor, Jabbari, Faryar, Series Editor, Jia, Limin, Series Editor, Kacprzyk, Janusz, Series Editor, Khamis, Alaa, Series Editor, Kroeger, Torsten, Series Editor, Li, Yong, Series Editor, Liang, Qilian, Series Editor, Martín, Ferran, Series Editor, Ming, Tan Cher, Series Editor, Minker, Wolfgang, Series Editor, Misra, Pradeep, Series Editor, Mukhopadhyay, Subhas, Series Editor, Ning, Cun-Zheng, Series Editor, Nishida, Toyoaki, Series Editor, Oneto, Luca, Series Editor, Panigrahi, Bijaya Ketan, Series Editor, Pascucci, Federica, Series Editor, Qin, Yong, Series Editor, Seng, Gan Woon, Series Editor, Speidel, Joachim, Series Editor, Veiga, Germano, Series Editor, Wu, Haitao, Series Editor, Zamboni, Walter, Series Editor, Tan, Kay Chen, Series Editor, Qu, Yi, editor, Gu, Mancang, editor, Niu, Yifeng, editor, and Fu, Wenxing, editor

Published
2024
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22. Routh-Hurwitz criterion of stability and robust stability for fractional-order systems with order {\alpha}{\in}[1,2)

Author

Yang, Jing, Hou, Xiaorong, and Li, Yajun

Subjects
Mathematics - Dynamical Systems
Abstract

Based on the generalized Routh-Hurwitz criterion, we propose a sufficient and necessary criterion for testing the stability of fractional-order linear systems with order {\alpha}{\in}[1,2), called the fractional-order Routh-Hurwitz criterion. Compared with the existing criterion, our one involves fewer and simpler expressions, which is significant for analyzing robust stability of fractional-order uncertain systems. All these expressions are explicit ones about the coefficients of the characteristic polynomial of system matrix, so the stable parameter region of fractional-order uncertain systems can be described directly. Some examples show the effectiveness of our method.

Published
2022

40. China Anti-Cancer Association (CACA) guidelines for holistic integrative management of lymphoma (version 2022)

Author

Zhang, Qingyuan, Feng, Jifeng, Wang, Huaqing, Huang, Huiqiang, Zhang, Huilai, Li, Xiaoqiu, Gao, Yuhuan, Song, Yongping, Li, Zhiming, Bai, Ou, Cao, Junning, Zhou, Hui, Gu, Kangsheng, Zhao, Shu, Zhao, Wenhui, Qin, Yan, Li, Yajun, Ma, Guangyu, Wen, Shujuan, Wang, Yu, Zhao, Peiqi, Guo, Wei, Lv, Fangfang, Tian, Yuyang, Chen, Xinrui, Xie, Zucheng, and Shi, Yuankai

Published
2023
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45. Multiple Angle Impact Guidance Law Design for Hypersonic Guided Rockets

Author

Li, Jinping, Mao, Zhaoyong, Li, Yajun, Chang, Guannan, Angrisani, Leopoldo, Series Editor, Arteaga, Marco, Series Editor, Panigrahi, Bijaya Ketan, Series Editor, Chakraborty, Samarjit, Series Editor, Chen, Jiming, Series Editor, Chen, Shanben, Series Editor, Chen, Tan Kay, Series Editor, Dillmann, Rüdiger, Series Editor, Duan, Haibin, Series Editor, Ferrari, Gianluigi, Series Editor, Ferre, Manuel, Series Editor, Hirche, Sandra, Series Editor, Jabbari, Faryar, Series Editor, Jia, Limin, Series Editor, Kacprzyk, Janusz, Series Editor, Khamis, Alaa, Series Editor, Kroeger, Torsten, Series Editor, Li, Yong, Series Editor, Liang, Qilian, Series Editor, Martín, Ferran, Series Editor, Ming, Tan Cher, Series Editor, Minker, Wolfgang, Series Editor, Misra, Pradeep, Series Editor, Möller, Sebastian, Series Editor, Mukhopadhyay, Subhas, Series Editor, Ning, Cun-Zheng, Series Editor, Nishida, Toyoaki, Series Editor, Oneto, Luca, Series Editor, Pascucci, Federica, Series Editor, Qin, Yong, Series Editor, Seng, Gan Woon, Series Editor, Speidel, Joachim, Series Editor, Veiga, Germano, Series Editor, Wu, Haitao, Series Editor, Zamboni, Walter, Series Editor, Zhang, Junjie James, Series Editor, Fu, Wenxing, editor, Gu, Mancang, editor, and Niu, Yifeng, editor

Published
2023
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46. Method of Locating the Strike Point on Pest for Laser Control Based on Mask R-CNN

Author

Li, Yajun, Xiang, Yang, Feng, Qingchun, Angrisani, Leopoldo, Series Editor, Arteaga, Marco, Series Editor, Panigrahi, Bijaya Ketan, Series Editor, Chakraborty, Samarjit, Series Editor, Chen, Jiming, Series Editor, Chen, Shanben, Series Editor, Chen, Tan Kay, Series Editor, Dillmann, Rüdiger, Series Editor, Duan, Haibin, Series Editor, Ferrari, Gianluigi, Series Editor, Ferre, Manuel, Series Editor, Hirche, Sandra, Series Editor, Jabbari, Faryar, Series Editor, Jia, Limin, Series Editor, Kacprzyk, Janusz, Series Editor, Khamis, Alaa, Series Editor, Kroeger, Torsten, Series Editor, Li, Yong, Series Editor, Liang, Qilian, Series Editor, Martín, Ferran, Series Editor, Ming, Tan Cher, Series Editor, Minker, Wolfgang, Series Editor, Misra, Pradeep, Series Editor, Möller, Sebastian, Series Editor, Mukhopadhyay, Subhas, Series Editor, Ning, Cun-Zheng, Series Editor, Nishida, Toyoaki, Series Editor, Oneto, Luca, Series Editor, Pascucci, Federica, Series Editor, Qin, Yong, Series Editor, Seng, Gan Woon, Series Editor, Speidel, Joachim, Series Editor, Veiga, Germano, Series Editor, Wu, Haitao, Series Editor, Zamboni, Walter, Series Editor, Zhang, Junjie James, Series Editor, Yan, Liang, editor, and Deng, Yimin, editor

Published
2023
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47. Input-Constrained Fuzzy Adaptive Control for Hypersonic Flight Vehicles Using System Extension Approach

Author

Li, Yajun, Li, Jinping, Chang, Jiang, Wang, Gen, Miao, Haochun, Angrisani, Leopoldo, Series Editor, Arteaga, Marco, Series Editor, Panigrahi, Bijaya Ketan, Series Editor, Chakraborty, Samarjit, Series Editor, Chen, Jiming, Series Editor, Chen, Shanben, Series Editor, Chen, Tan Kay, Series Editor, Dillmann, Rüdiger, Series Editor, Duan, Haibin, Series Editor, Ferrari, Gianluigi, Series Editor, Ferre, Manuel, Series Editor, Hirche, Sandra, Series Editor, Jabbari, Faryar, Series Editor, Jia, Limin, Series Editor, Kacprzyk, Janusz, Series Editor, Khamis, Alaa, Series Editor, Kroeger, Torsten, Series Editor, Li, Yong, Series Editor, Liang, Qilian, Series Editor, Martín, Ferran, Series Editor, Ming, Tan Cher, Series Editor, Minker, Wolfgang, Series Editor, Misra, Pradeep, Series Editor, Möller, Sebastian, Series Editor, Mukhopadhyay, Subhas, Series Editor, Ning, Cun-Zheng, Series Editor, Nishida, Toyoaki, Series Editor, Oneto, Luca, Series Editor, Pascucci, Federica, Series Editor, Qin, Yong, Series Editor, Seng, Gan Woon, Series Editor, Speidel, Joachim, Series Editor, Veiga, Germano, Series Editor, Wu, Haitao, Series Editor, Zamboni, Walter, Series Editor, Zhang, Junjie James, Series Editor, Yan, Liang, editor, and Deng, Yimin, editor

Published
2023
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48. Strategy of Chinese Medicine Animation in TCM Culture Communication

Author

Xue, Jingying, Li, Yajun, Striełkowski, Wadim, Editor-in-Chief, Black, Jessica M., Series Editor, Butterfield, Stephen A., Series Editor, Chang, Chi-Cheng, Series Editor, Cheng, Jiuqing, Series Editor, Dumanig, Francisco Perlas, Series Editor, Al-Mabuk, Radhi, Series Editor, Scheper-Hughes, Nancy, Series Editor, Urban, Mathias, Series Editor, Webb, Stephen, Series Editor, Chen, Youbin, editor, Anthony, Marcus T., editor, and Ke, Yan, editor

Published
2023
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