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An explanation for the peculiar periphery of supernova remnant G309.2–0.6

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Research in Astronomy and Astrophysics 2018年第9期18卷 133-140页

作者： Huan Yu jun fang Department of Physical Science and Technology Kunming University Department of Astronomy Key Laboratory of Astroparticle Physics of Yunnan Province Yunnan University

Supernova remnant（SNR） G309.2–0.6 has a peculiar radio morphology with two bright ears to the southwest and northeast, although the main shell outside the ears is roughly circular. Based on an earlier proposal that the supernova ejecta has a jet component with extra energy, the dynamical evolution of the remnant is solved using 3 D hydrodynamical（HD） simulation to investigate the formation of the periphery of the remnant. Assuming the ejecta with a kinetic energy of 10^51 erg and a mass of 3 M⊙evolved in a uniform ambient medium for a time of-4000 yr and the jet component has cylindrical symmetry with a half open angle of 10°, the result indicates that the energy contained in the jet is about10%–15% of the kinetic energy of the entire ejecta to reproduce the detected profile. This study supports that the remnant originated from a jet-driven core-collapse supernova.

关键词： hydrodynamics(HD) - methods numerical - ISM supernova remnants

Plastic deformation analysis and forming quality prediction of tube N C bending

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Chinese Journal of Aeronautics 2016年第5期29卷 1436-1444页

作者： Lu Shiqiang fang jun Wang Kelu National Defense Key Disciplines Laboratory of Light Alloy Processing Science and Technology School of Aeronautical Manufacturing Engineering Nanchang Hangkong University Nanchang 330063 China Jiangxi Key Laboratory of Surface Engineering Jiangxi Science and Technology Normal University Nanchang 330013 China

Plane strain assumption and exponent hardening law are used to investigate the plastic deformation in tube bending. Some theoretical formulae including stress, curvature radius of neutral layer, angle of neutral layer deviation, bending moment, wall thickness variation and crosssection distortion, are developed to explain the phenomena in tube bending and their magnitudes are also determined. During unloading process, the springback angle is deduced using the virtual work principle, and springback radius is also given according to the length of the neutral layer which remains unchanged before and after springback. The theoretical formulae are validated by the experimental results or the validated simulation results in literature, which can be used to auicklv predict the forming aualitv of tube numerical control （NC） bending.

关键词： Forming quality Plane strain Tube NC bending Theoretical analysis Virtual work principle

Studying the Fermi GeV light curve of Vela with the two-pole caustic model

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Research in Astronomy and Astrophysics 2009年第12期9卷 1324-1330页

作者： Huan Yu jun fang Ze-jun Jiang Department of Physics Yunnan University Kunming 650091 China

An observation of the Vela pulsar with the Fermi Large Area Telescope has been recently reported and the GeV light curve shows two main peaks with a phase separation of ～0.43. We study the GeV light curve using the two-pole caustic model in which the peaks of the light curves of the pulsar result from caustic effects. The results show that the two-pole caustic model can reproduce the observed emission pattern of the two peaks and the bridge emission between them well, but overestimates the flux outside the two peaks. After taking account of the pair production effect on the azimuthal angle, we find that the resulting light curve is more consistent with the observation. We excluded the emissions from the field lines for which the distance from the null charge surface, where the pairs can be significantly produced, is larger than the radius of the light cylinder.

关键词： gamma rays: theory -- pulsars: individual (PSR B0833-45)

Hadronic Scenarios for Gamma-Ray Emission from Three Supernova Remnants Interacting with Molecular Clouds

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Chinese Physics Letters 2014年第4期31卷 206-209页

作者： YU Huan fang jun ZHANG Li Department of Physics Yunnan University Kunming 650091 Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Kunming 650011

GeV γ-rays detected with the large area telescope on board the Fermi Gamma-ray space telescope in the direc- tion of HB21, MSH 17-39 and G337.0-0.1 have been recently reported. The three supernova remnants （SNRs） show interactions with molecular clouds, and they are effective gamma-ray emitters as the relativistic protons accelerated by the SNR shocks inelastically colliding with the dense gas in the clouds. The origin of the observed γ-rays for the three remnants is investigated in the scenario of the diffusive shock acceleration. In the model, a part of the SNR shock transmits into the nearby molecular clouds, and the shock velocity is greatly reduced. As a result, a shock with a relatively low Alfven Mach number is generated, and the spectra of the accelerated protons and thee＇γ-ray photons produced via proton-proton interaction can be obtained. The results show that the observed γ-ray spectra for the three SNRs interacting with the molecular clouds can be reproduced. It can be concluded that the hadronic origin of the γ-rays for the three SNRs is approved, and the ability of SNR shocks to accelerate protons is also supported.

关键词： HADRONIC atoms GAMMA-ray absorption SUPERNOVA remnants PROTON-proton interactions PLASMA Alfven waves

Effects of retained dry material on the impact,overflow and landing dynamics

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Journal of Rock Mechanics and Geotechnical Engineering 2024年第9期16卷 3629-3640页

作者： jun fang Yifei Cui Haiming Liu State Key Laboratory of Hydroscience and Engineering Tsinghua UniversityBeijingChina Department of Civil and Environmental Engineering The Hong Kong University of Science and TechnologyHong KongChina

During long-term operation,the performance of obstacles would be changed due to the material accumulating upslope the ***,the effects of retained material on impact,overflow and landing dynamics of granular flow have not yet been *** address this gap,physical flume tests and discrete element simulations are conducted considering a range of normalized deposition height h0/H from 0 to 1,where h0 and H represent the deposition height and obstacle height,*** analytical model is modified to evaluate the flow velocity and flow depth after interacting with the retained materials,which further serve to calculate the peak impact force on the ***,the computed impact forces successfully predict the experimental results when a≥25°.In addition,the results indicate that a higher h0/H leads to a lower dynamic impact force,a greater landing distance L,and a larger landing coefficient Cr,where Cr is the ratio of slope-parallel component of landing velocity to flow velocity just before *** to the existing overflow model,the measured landing distance L is underestimated by up to 30%,and therefore it is insufficient for obstacle design when there is retained ***,the recommended Cr in current design practice is found to be nonconservative for estimating the landing velocity of geophysical *** study provides insightful scientific basis for designing obstacles with deposition.

关键词： Granular flow Obstacle deposition Impact Overflow Landing

Relationship between Acute Organophosphorus Pesticide Poisoning and Damages Induced by Free Radicals

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Biomedical and Environmental Sciences 2002年第2期15卷 177-186页

作者： ZHOU jun-FU XU GEN-BO fang WEI-jun SecondAffiliatedHospitalofCollegeofMedicine ZhejiangUniversity88JiefangRoadHangzhou310009ZhejiangProvinceChina

OBJECTIVE: To study the relationship between abnormal reactions of free radicals in bodies of patients with acute organophosphorus pesticide poisoning (AOPP) and damages induced by free radicals. METHODS: 58 AOPP patients and 58 healthy adult volunteers (HAV) were enrolled in an independent samples control design, in which spectrophotometric methods were used to determine the concentrations of nitric oxide (NO) and lipoperoxides (LPO) in plasma, and LPO in erythrocytes, vitamin C (VC), vitamin E (VE) and beta-carotene (beta-CAR) in plasma as well as activities of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px) and acetylcholinesterase (AChE) in erythrocytes. RESULTS: Compared with the average values of every biochemical parameter in the HAV group, the average values of LPO in plasma and in erythrocytes, and NO in plasma in the AOPP group were significantly increased (P = 0.000001), while the average values of VC, VE, beta-CAR in plasma as well as SOD, CAT, GSH-Px and AChE in erythrocytes in the AOPP group were significantly decreased (P = 0.000001). The findings of Pearson product-moment correlation analysis between the value of AChE in erythrocytes and the values of above biochemical parameters for 58 AOPP patients showed that there was a significant linear negative correlation between AChE in erythrocytes and LPO, NO in plasma, and LPO in erythrocytes (P = 0.000001-0.001319), while there was a significant linear positive correlation between AChE in erythrocytes and VC, VE, beta-CAR in plasma as well as SOD, CAT, GSH-Px in erythrocytes (P = 0.000013-0.000824). The results of discriminant analysis of above chemical parameters for 58 AOPP patients and 58 HAV suggested that the correct rates of discriminant analysis were increased to 100% when the values of AChE and LPO in plasma and in erythrocytes, or AChE and others, were jointly used for the discriminant analysis. CONCLUSION: The findings of the present study suggest that a series of fr

关键词： Organophosphorus pesticide poisoning Free radicals Lipoperoxides Nitric oxide Antioxidants Antioxidases

Longitudinal Vibration Analysis of Marine Riser During Installation and Hangoff in Ultra Deepwater

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Computer Modeling in Engineering & Sciences 2016年第4期111卷 357-373页

作者： Yanbin Wang Deli Gao jun fang MOE Key Laboratory of Petroleum Engineering China University of PetroleumBeijing102249China

This paper is concerned with the problem of longitudinal vibration of a 3,000 m long disconnected drilling riser during installation and hangoff *** natural frequency,amplitude of vibration displacement and vibration force of longitudinal vibration have been determined with consideration of the damping effect of the sea *** show the natural frequency of riser under these two situations are both decrease with the increase of water *** natural frequency of riser in installation operation is bigger than that in hangoff *** vibration displacement in hangoff configuration is bigger than that in installation while the vibration force in hangoff configuration is smaller than that in installation *** the condition of resonance,the vibration displacement increase along riser from top end to the bottom end while the vibration force increase along riser from riser bottom end to the top end.

关键词： Marine riser Installation Hangoff Longitudinal vibration

Narrow-Bandwidth Diode-Laser-Based Ultraviolet Light Source

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Chinese Physics Letters 2011年第10期28卷 103-105页

作者： PENG Yu fang Zhan-jun ZANG Er-jun Division of Electricity and Quantum Metrology National Institute of MetrologyBeijing 100013 Department of Precision Instruments and Mechanology Tsinghua UniversityBeijing 100084

A compact,tunable and narrow-bandwidth laser source for ultraviolet radiation is presented.A grating stabilized diode laser at 1064 nm is frequency-stabilized to below 10 kHz by using a ultra low expansion(ULE)*** light of the diode laser into a tapered amplifier yields a power of 290 *** a first frequency-doubling stage,about 47 mW of green light at 532 nm is generated by using a periodically poled KTP *** second-harmonic generation employing a BBO crystal leads to about 30µW of ultraviolet light at 266 nm.

关键词： amplifier tunable ultraviolet

A Pulsar Wind Nebula Origin of the Ultra-high-energy Source 1LHAASO J1929+1846

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Research in Astronomy and Astrophysics 2023年第10期23卷 218-223页

作者： Qi Xia Lian-Cheng Zhou jun fang Department of Astronomy Yunnan UniversityKunming 650091China

1LHAASO J1929+1846 is one of the ultra-high-energy(UHE,E>0.1 PeV)sources in the first catalog ofγ-ray sources detected by the Large High Altitude Air Shower *** has been detected fluxes at 3 TeV for2.48±0.11×10^(-13)TeV^(-1)cm^(-2)s^(-1)with the Water Cherenkov Detector Array and at 50 TeV for0.64±0.06×10^(-16)TeV^(-1)cm^(-2)s^(-1)with the Kilometer Squared Array,but the origin of its UHE emission remains *** pulsar wind nebula(PWN)G54.1+0.3,which is powered by the pulsar PSR 1930+1852with a period of 136 ms and it is detected within a 0°.29 region around the centroid of 1LHAASO J1929+*** explore whether G54.1+0.3 is capable of producing the UHE radiation of 1LHAASO J1929+***,the data with Fermi Large Area Telescope for the PWN is analyzed to obtain the GeV ***,the multiband nonthermal fluxes for the nebula are investigated based on a one-zone time-dependent *** the model,we assume the spin-down energy of the pulsar is persistently injected into particles(electrons and positrons)and magnetic field in the PWN,and these high-energy particles produce multiband non-thermal radiation from radio toγ-rays via synchrotron radiation and inverse Compton *** reproduce the spectral energy distribution of PWN G54.1+0.3 with reasonable *** result indicates that the UHEγ-ray source 1LHAASO J1929+1846possibly originates from PWN G54.1+0.3.

关键词： radiation mechanisms:non-thermal ISM:supernova remnants gamma-rays:stars