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| 1 | Pulse phase and doppler frequency estimation of X-ray pulsars under conditions of spacecraft and binary motion and its application in navigation显示文摘The pulse phase and doppler frequency estimation of X-ray pulsars in dynamic situations and its application in navigation is a problem that has not been fully investigated. In this paper, solutions are proposed to solve this problem under conditions of spacecraft and binary motion. A high-precision doppler frequency (velocity) measurement model as well as a phase (range) measurement model is established. The averaged maximum-likelihood estimator is developed for the dynamic pulse phase estimation. The pulse phase tracking technique is used in the doppler frequency determination. The tracking filter is redesigned and compared with the existing algorithms. The comparison verifies the advantage of the filter algorithm presented in this pa- per. Unlike traditional views, it is found that in dynamic situations, shorter observation interval lengths will result in higher-accuracy phase and frequency estimates as the tracking filter outputs. A photon-level integrated numerical simulation is performed. Simulation results testify to the validity of the proposed phase and doppler frequency estimation scheme, and show that incorporation of velocity measurements as well as the range ones into the navigation estimator will improve the navigation steady-state performance. | HUANG LiangWei LIANG Bin ZHANG Tao | 2013 | Science China(Physics,Mechanics & Astronomy)2013，56，4： | 11 |
| 2 | Leaf choice in black-and-white snub-nosed monkeys Rhinopithecus bieti is related to the physical and chemical properties of leaves显示文摘To understand the effects of the chemical and physical properties of plant leaves on food choice in Rhinopithecus bieti,we collected mature leaves of nine food and five non-food plant species at the southernmost part of the species's range.Chemical properties such as fat, ash, crude protein (CP), total phenolics (TP), and fiber content including neutral detergent fiber(NDF), acid detergent fiber (ADF), lignin, celluloses and hemicelluloses, and physical toughness were measured. R. bieti tendedto choose leaves with lower fiber content, higher ash, a higher ratio of CP/ADF, and lower toughness. No difference was foundfor fat, crude protein, total phenolics, hemicelluloses and lignin between food and non-food leaves. Even though the ratio ofCP/ADF is generally regarded as a good indicator for colobine food choice, the difference in the ratio of CP/ADF between foodand non-food leaves was only the result of differences in ADF. Since positive correlations were found between ADF and toughnessfrom all leaves (both food and non-food species), and toughness of leaves was likely easier for R. bieti to sense than fibercontent via mastication, the toughness of leaves may function as a predictor of food choice in this species. | Zhipang HUANG Sheng HUO Shuguo YANG Liangwei CUI Wen XIAO | 2010 | Current Zoology2010，56，6： | 6 |
| 3 | Navigation using binary pulsars显示文摘The issue of navigation using binary pulsars is investigated in this paper.We show how the effect of the binary motion is incorporated in the navigation measurement equation.Necessary reference systems and time scales are introduced and the transformation between different time scales is derived.Based mainly on Damour and Deruelle's binary model and the TEMPO2 software,the timing model resolving the time delay from emission to arrival is established with the solar system,interstellar and binary system delays included,which retains all the terms exceeding 1 ns.The navigation measurement equation is thus built and the parameters needed are listed.A comparison is made between Sheikh's measurement equation and that in this paper.It is found that it is not necessary to introduce a fictitious SSB arrival time as Sheikh does.Near-Earth navigation for the Keplerian orbit in the case of observing one pulsar is investigated.The uncertainties of the orbit parameters are derived using the least square fitting method,which reveals that observing one pulsar enables one to navigate near-Earth spacecraft. | HUANG LiangWei LIANG Bin ZHANG Tao ZHANG CaiHong | 2012 | Science China(Physics,Mechanics & Astronomy)2012，55，3： | 3 |
| 4 | Long-term variations of X-ray pulse profiles for the Crab pulsar:data analysis and modeling显示文摘The pulse profiles of the Crab pulsar(as well as some other pulsars)vary with time.They can lead to a major source of intrinsic timing noise,which lacks a detailed physical model.The phase separation?between the first left peak(P1)and the second right peak(P2)is a key parameter that shows the variations of pulse profiles for the Crab pulsar.It was found that the evolution of?has a tendency with increasing rates of 0.82?±0.25?,0.80?±0.54?,and 0.77?±0.28?per century for the 2-6,6-15,and15-60 ke V bands,respectively.Furthermore,the flux ratios(P2/P1)of X-ray pulse profiles in the three bands were calculated,and the derived flux ratios were consistent with the radio and X-ray measurements of the Insight-HXMT.In addition to discovering the physical origin of the pulse changes,the high-SNR X-ray pulse profiles were simulated in the annular gap model,and two model parameters(e.g.,the maximum emission heights of the two peaks)were observed to slightly affect the variations of peak separation.We fitted the long-term variations of emission heights of the two peaks and discovered that the emission heights showed increasing tendencies with time.Variations of these emission heights induced a characteristic period derivative,and a complete formula for both the magnetic dipole radiation and wind-particle-induced variations of the moment of inertia was used for the pulsar’s spin-down to obtain the variation rate˙αof the magnetic inclination angle,which was-1.60?per century.Intrinsic timing noise is observed to be mainly induced by the variations of pulse profiles,which might correlate with a characteristic spin period derivative arising from the fluctuations of the emission regions.This work will lay a foundation for understanding the origin of intrinsic timing noise and making high-precision timing models in the future. | LunHua Shang YuanJie Du XiangQun Cui ShiJun Dang JiGuang Lu JunTao Bai QiJun Zhi YouLi Tuo LinLi Yan LiangWei Huang XinYuan Zhang XiaoMin Bei QingQing Lin GuoJun Qiao Hua Shen RiHong Zhu | 2020 | Science China(Physics,Mechanics & Astronomy)2020，63，10： | 2 |
| 5 | A thioredoxin reductase and/or thioredoxin system-based mechanism for antioxidant effects of ambroxol显示文摘 | Jin Huang Jianying Xu Lin Tian Liangwei Zhong | 2014 | Biochimie2014，，： | 1 |
| 6 | Numerical Study of Convective and Radiation Heat Transfer Characteristics in an Upward-Facing Cylindrical Cavity under Back-Side Windy Condition显示文摘Under the back-side windy condition,the convection and radiation heat transfer characteristics in an iso-flux upward-facing cylindrical cavity were studied by three-dimensional numerical simulation.The impacts of cavity tilt angle,wind incident angle and wind speed on convection and radiation heat transfer Nusselt number Nuc and Nur were analyzed,and the possible explanations for their impacts were presented.Results show that due to the disturbance of wind,the influence of cavity tilt angle becomes more complicated and is related to wind incident angle and wind speed.The variation of Nuc or Nur with wind incident angle is different for different cavity tilt angles.Despite of the changes of cavity tilt angle or wind incident angle,the Nuc increases with the wind speed while the Nur presents a declination with the increasing of wind speed.Hence,compared with cavity tilt angle and wind incident angle,wind speed may be the dominant factor affecting or controlling the convective and radiation heat transfer of cavity. | WANG Zehui WU Kefeng WANG Ti XIA Liangwei YU Qiang HUANG Ying SUN Hao WEI Guohua GUAN Jingyu YAN Yanfei | 2021 | Journal of Thermal Science2021，30，1： | 0 |
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