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Search Results: 1 - 10 of 414981 matches for " J. H. Fan "
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Infrared Variation of Blazars
J. H. Fan
Physics , 1999,
Abstract: In this paper, the historical infrared (JHK) data compiled from the published literature are presented here for 30 blazars. Maximum near-IR variations are found and compared with the optical ones. For the color-magnitude relation, some objects show that the color index increases with magnitude while 1253-055 shows complex behaviour, which perhaps suggests that the emission mechanism consists of, at least, two parts. The spectral indexes are in the range of $\alpha_{IR}$ = 0.77 to 2.37.
Long-term Variability Properties and Periodicity Analysis for Blazars
J. H. Fan
Physics , 2000,
Abstract: In this paper, the compiled long-term optical and infrared measurements of some blazars are used to analyze the variation properties and the optical data are used to search for periodicity evidence in the lightcurve by means of the Jurkevich technique and the discrete correlation function (DCF) method. Following periods are found: 4.52-year for 3C 66A; 1.56 and 2.95 years for AO 0235+164; 14.4, 18.6 years for PKS 0735+178; 17.85 and 24.7 years for PKS 0754+100; 5.53 and 11.75 for OJ 287. 4.45, and 6.89 years for PKS 1215; 9 and 14.84 years for PKS 1219+285; 2.0, 13.5 and 22.5 for 3C273; 7.1 year for 3C279; 6.07 for PKS 1308+326; 3.0 and 16.5 years for PKS 1418+546; 2.0 and 9.35 years for PKS 1514-241; 18.18 for PKS 1807+698; 4.16 and 7.0 for 2155-304; 14 and 20 years for BL Lacertae. Some explanations have been discussed.
BL Lac Objects and Relativistic Beaming Model
J. H. Fan
Physics , 1998,
Abstract: In this paper: 1. The assumption of the dependence of Doppler factor on the emission frequency (Fan et al. 1993) is used to explain the observational differences between the radio-selected BL Lac objects(RBLs) and the X-Ray-Selected BL Lac objects (XBLs): a) Hubble relation; b) different multiwavelength correlations; c) different regions in the effective spectral index diagram; d) different polarization. The results suggest that RBLs and XBLs are the same. 2. From the analysis of the relation between infrared magnitude and redshift, it is proposed that the parent population of BL Lac objects should be FRI radio galaxies and FRII(G) radio galaxies showing the optical spectra of a galaxy. 3. From the superluminal motion, the assumption (Fan et al. 1993) is confirmed. 4. Based on the relation between polarization and Doppler factor (Fan et al. 1997, A&A, 327, 947), it is proposed that the ratio of the beamed luminosity to the unbeamed luminosity in the source frame of OVVs/HPQs is smaller than that of BL Lac objects.
Relation between $γ$-rays and emission lines for the $γ$-ray loud blazars
J. H. Fan
Physics , 2000,
Abstract: The relation between the $\gamma$-ray and the emission line luminosities for a sample of 36 $\gamma$-ray loud blazars is investigated; an apparent correlation between them, $L_{\gamma} \propto L_{Line}^{0.69\pm0.11}$, with a correlation coefficient $r=0.741$ and a chance probability of $p = 1.9\times10^{-6}$, is found. It is found, however, that there is no intrinsic correlation between them: the apparent correlation is due to the redshift dependence in a flux-limited sample. Thus no evidence is found to support the argument that the up-scattered soft photons are from the broad emission lines. Our analysis does not conflict with the SSC model. The disk-jet symbiosis and radio/$\gamma$-ray correlation found in the literature are also discussed. The radio/$\gamma$-ray correlation may be an apparent correlation caused by the boosting effect since both bands are strongly beamed.
Long-term infrared variation of 3C 279 and 4C 29.45
J. H. Fan
Physics , 1999,
Abstract: In this paper, the historical infrared (JHK) data compiled from 22 publications are presented for 3C279 and 4C29.45. Relation between color index and magnitude and between color-color indices are discussed. (J-K) is found closely correlated with (J-H) while (J-H) is almost not correlated with (H-K), which is perhaps due to two facts of (1) (J-K) shows wider distribution than (J-H) and (H-K) and (2) the spectrum deviates from the power law. For color-magnitude relation, there is a correlation of color index increasing with magnitude for 3C279 suggesting that the spectrum flattens when the source brightens. But an opposite tendency is also noted between (H-K) and J when I is fainter than 14 magnitude, which suggests that the near-IR spectrum of 3C279 consists of, at least, two components. No similar result is found for 4C29.45. The largest amplitude infrared variation is smaller than but comparable with the largest amplitude variation for the two objects.
Quantum discord: "discord" between the whole and its constituent
X. -J. Ren,H. Fan
Mathematics , 2011, DOI: 10.1088/1751-8113/45/42/425304
Abstract: Quantum discord, a measure of quantum correlation beyond entanglement, is initially defined as the discord between two classically equivalent while quantum discordant definitions of mutual information. In this paper, we report some new interpretations of discord which rely on the differences between measurement induced effects on the local measured system and the whole system. Specifically, with proper quantitative definitions introduced in [Buscemi, Hayashi and Horodecki, Phys. Rev. Lett. 100, 2210504 (2008)], we find that quantum discord can be interpreted as the differences of measurement induced disturbance or information gain on the local measured system and on the whole system. Combined with previous similar results based on measurement induced entanglement and decoherence, our results provide a unified view on quantum discord.
The variability analysis of PKS 2155-304
J. H. Fan,R. G. Lin
Physics , 2000,
Abstract: In this paper, the post-1977 photometric observations of PKS 2155-304 are compiled and used to discuss the variation periodicity. Largest amplitude variations ($\Delta U = 1^{m}.5$; $\Delta B = 1^{m}.65$; $\Delta V = 1^{m}.85 $; $\Delta R = 1^{m}.25$; $\Delta I = 1^{m}.14 $) and color indices ($(B-V) = 0.30\pm 0.06$; $(U-B) = -0.72\pm 0.08$; $(B-R) = 0.62\pm 0.07$; $(V-R) = 0.32\pm 0.04$) are found. The Jurkevich's method and DCF (Discrete Correlation Function) method indicate possible periods of 4.16-year and 7.0-year in the V light curve.
Infrared Variation of Radio Selected BL Lacertae Objects
J. H. Fan,R. G. Lin
Physics , 1999, DOI: 10.1086/313191
Abstract: In this paper, the historical infrared (JHK) data compiled from the published literature are presented in electronic form for 40 radio selected BL Lacertae objects (RBLs) for the first time. Largest variations are found and compared with the largest optical variation. Relations between color index and magnitude and between color-color indices are discussed individually. For the color-magnitude relation, some objects (0048-097, 0735+178, 0851+202, 1215+303, 1219+285, 1749+096, and perhaps 0219+428, 0537-441, 1514-241) show that color index increases with magnitude indicating that the spectrum flattens when the source brightens while some other objects (0754+100, 1147+245, 1418+546, and 1727+502) perhaps show an opposite behaviour, while remaining objects do not show any clear tendency; For color-color relation, it is found common that (J-K) is closely correlated with (J-H) while (J-H) is not correlated with (H-K).
Research on DC Fault of Multi-Terminal Direct Current System  [PDF]
S. Y. Fan, J. Liu, E. M. Bian, H. T. Xu, C. L. Kang
Energy and Power Engineering (EPE) , 2017, DOI: 10.4236/epe.2017.94B081
Abstract:
This paper introduces the characteristics of VSC and MMC-MTDC and discusses the effects of different kinds of faults in HVDC systems. Special attention is given to the comparison between a pole-to-pole fault and a pole-to-ground fault occurring in the middle of the line or at the terminal of a VSC. Simulations using MATLAB are provided in this article which show the difference effects clearly when faults occur in a VSC-MTDC system or in a MMC-MTDC system. Understanding of such fault characteristics and the influence of the control system on them are important prerequisites on the way to MTDC systems.
The optical microvariability and spectral changes of the BL Lacertae object S5 0716+714
H. Poon,J. H. Fan,J. N. Fu
Physics , 2009, DOI: 10.1088/0067-0049/185/2/511
Abstract: We monitored the BL Lac object S5 0716+714 in the optical band during October 2008, December 2008 and February 2009 with a best temporal resolution of about 5 minutes in the BVRI bands. Four fast flares were observed with amplitudes ranging from 0.3 to 0.75 mag. The source remained active during the whole monitoring campaign, showing microvariability in all days except for one. The overall variability amplitudes are delta B ~ 0.89 mag, delta V ~ 0.80 mag, delta R ~ 0.73 mag and delta I ~0.51 mag. Typical timescales of microvariability range from 2 to 8 hours. The overall V - R color index ranges from 0.37 to 0.59. Strong bluer- when-brighter chromatism was found on internight timescales. However, different spectral behavior was found on intranight timescales. A possible time lag of ~ 11 mins between B and I bands was found on one night. The shock-in-jet model and geometric effects can be applied to explain the source's intranight behavior.
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