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Hydrodynamical simulations of the triggering of nuclear activities by minor mergers of galaxies

Research in Astronomy and Astrophysics 2019年第12期19卷 245-256页

作者： Chao Yang jun-Qiang Ge you-jun Lu National Astronomical Observatories Chinese Academy of SciencesBeijing 100101China School of Astronomy and Space Sciences University of Chinese Academy of SciencesBeijing 100049China CAS Key Laboratory for Computational Astrophysics National Astronomical ObservatoriesChinese Academy of SciencesBeijing 100101China

Major mergers of galaxies are considered to be an efficient way to trigger Active Galactic Nuclei and are thought to be responsible for the phenomenon of quasars. This has however recently been challenged by observations of a large number of low luminosity Active Galactic Nuclei at low redshift(z■1) without obvious major merger signatures. Minor mergers are frequently proposed to explain the existence of these Active Galactic Nuclei. In this paper, we perform nine high resolution hydrodynamical simulations of minor galaxy mergers, and investigate whether nuclear activities can be efficiently triggered by minor mergers, by setting various properties for the progenitor galaxies of those mergers. We find that minor galaxy mergers can activate the massive black hole in the primary galaxy with an Eddington ratio of f Edd > 0.01 and> 0.05(or a bolometric luminosity > 10^43 and > 10^44 erg s^-1) with a duration of 2.71 and 0.49 Gyr(or 2.69 and 0.19 Gyr), respectively. The nuclear activity of the primary galaxy strongly depends on the nucleus separation, such that the nucleus is more active as the two nuclei approach each other. Dual Active Galactic Nuclei systems can still possibly be formed by minor mergers of galaxies, though the time duration for dual Active Galactic Nuclei is only ~ 0.011 Gyr and ~ 0.017 Gyr with Eddington ratio of f Edd > 0.05 and bolometric luminosity > 10^44 erg s^-1. This time period is typically shorter than that of dual Active Galactic Nuclei induced by major galaxy mergers.

关键词： galaxies:binary quasars:general methods:n-body simulations

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Investigating the co-evolution of massive black holes in dual active galactic nuclei and their host galaxies via galaxy merger simulations

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Science China(Physics,Mechanics & Astronomy) 2019年第12期62卷 96-109页

作者： Chao Yang junQiang Ge you jun Lu National Astronomical Observatories Chinese Academy of SciencesBeijing 100012China School of Astronomy and Space Sciences University of Chinese Academy of SciencesBeijing 100049China CAS Key Laboratory for Computational Astrophysics National Astronomical ObservatoriesChinese Academy of SciencesBeijing 100012China

Major galaxy mergers can trigger nuclear activities and are responsible for high-luminosity quasi-stellar objects/active galactic nuclei(QSOs/AGNs). In certain circumstances, such mergers may cause dual active galactic nuclei(dAGN) phenomenon. This study investigates dAGN triggering and evolution of massive black holes(MBHs) during the merging processes using hydrodynamic code GADGET-2 to simulate several gas-rich major mergers at redshift z = 2 and 3, respectively. Results reveal that gas-rich major mergers can trigger significant nuclear activities after the second and third pericentric passages and the formation of dAGN with significant time duration(~10-390 Myr). During the merging processes, galactic bulge evolves with time because of the rapid star formation in each(or both) galactic centers and initial mixing of stars in galactic disks due to violent *** grow substantially due to accretion and finally merge into a bigger black hole. The growth of galactic bulges and corresponding increases of its velocity dispersions predate the growth of MBHs in the d AGN stages. The MBHs in these stages deviate below the relation between MBH mass and bulge mass(or velocity dispersion), and they revert to the relation after the final mergers due to the significant accretion that occurs mostly at a separation less than a few kpc. Then, the two MBHs merge with each other.

关键词： galaxies quasars black hole numerical simulations

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Existence of Sign-Changing Solutions for the p-Laplacian Equation from Linking Type Theorem

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Acta Mathematica Sinica,English Series 2010年第7期26卷 1355-1368页

作者： you jun WANG Yao Tian SHEN Department of Mathematics South China University of Technology Guangzhou 510640 P. R. China

In this paper, the existence of sign-changing solutions for p-Laplacian equation is obtained via a new linking theorem.

关键词： sign-changing solutions p-Laplacian (w-PS) condition linking

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A Modified Landweber Iteration for General Sideways Parabolic Equations

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Acta Mathematicae Applicatae Sinica 2011年第4期27卷 727-738页

作者： Jin-bo LIU you-jun DENG Department of Mathematics Changsha University of Science and Technology Changsha 410076 China School of Mathematical Sciences and Computing Technology Central South University Changsha Hunan 410075China

Abstract In this paper, we introduce a modified Landweber iteration to solve the sideways parabolic equation, which is an inverse heat conduction problem （IHCP） in the quarter plane and is severely ill-posed. We shall show that our method is of optimal order under both a priori and a posteriori stopping rule. Furthermore, if we use the discrepancy principle we can avoid the selection of the a priori bound. Numerical examples show that the computation effect is satisfactory.

关键词： inverse heat conduction problem sideways parabolic equation Landweber iteration,discrepancy principle

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减氮及有机肥替代对旱地冬小麦干物质积累、转运、分配和产量的影响

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作物学报 2025年第1期51卷 207-220页

作者：张军胡川周起晖任开明董誓言刘傲寒吴金芝黄明李友军河南科技大学农学院河南洛阳471023 商洛学院生物医药与食品工程学院陕西商洛726000

探究减氮及有机肥替代对旱地冬小麦产量形成和经济效益的影响,为实施化肥减量和有机肥替代提供理论和技术依据。2021-2023年度,基于2019年开始设置在黄土高原和黄淮海平原交汇处典型旱地冬小麦产区(河南洛宁和河南孟津)的定位试验,研究... 详细信息

探究减氮及有机肥替代对旱地冬小麦产量形成和经济效益的影响,为实施化肥减量和有机肥替代提供理论和技术依据。2021-2023年度,基于2019年开始设置在黄土高原和黄淮海平原交汇处典型旱地冬小麦产区(河南洛宁和河南孟津)的定位试验,研究了冬小麦干物质积累转运分配特性、氮肥干物质生产效率、产量及其构成要素和经济效益。试验设置不施氮肥(NN)、农户施氮(FN)、基于FN减氮20%(RN)和RN基础上20%氮肥用有机肥替代(OSN)4个处理。结果表明:(1)与FN相比,RN处理降低了小麦拔节期、开花期和成熟期的干物质积累量、花前干物质转运量以及成熟期茎鞘、穂轴+颖壳和籽粒的干物质分配量,但对籽粒产量无显著影响。(2)与FN和RN相比, OSN处理提高了各生育阶段的氮肥干物质生产效率,从而增加了拔节期、开花期、成熟期的干物质积累量,而且提高了花前干物质转运量、花后干物质积累量、花后干物质积累量对籽粒的贡献率,进而使成熟期地上部各器官的干物质分配量均得到显著提高,最终使籽粒产量分别显著增加15.03%和17.12%,经济效益增加3.84%和4.23%。(3)小麦产量与花前干物质转运量、花后干物质积累量和花后干物质积累量对籽粒的贡献率呈极显著正相关,与花前干物质转运量对籽粒的贡献率呈极显著负相关。综上,在雨养条件下,小麦季施氮量为172kghm^(–2) (夏休闲-冬小麦)和192kg hm^(–2) (夏玉米-冬小麦)的基础上,OSN处理提高了氮肥干物质生产效率,增加各生育时期的干物质积累量,其花前干物质转运量和花后干物质积累量的协同增加使其获得了最高产量,实现增产增收,适宜在产量水平为5000kghm^(–2)的雨养旱地冬小麦高产栽培中应用。

关键词：旱地冬小麦减氮有机肥替代干物质积累转运产量经济效益

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Effect of Cu toxicity at different salinity on selective group of juvenile pompano Trachinotus ovatus

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热带海洋学报 2014年第4期33卷 26-32页

作者： OU you-jun South China Sea Fisheries Research Institute Chinese Academy of Fishery Sciences Key Laboratory of South China Sea FisheryResources Exploitation & Utilization Ministry of Agriculture Guangzhou 510300 China

Effects of copper toxicity and salinity shock on selective group of juvenile pompano Trachinotus ovatus were *** fish were exposed to different Cu2+ concentrations of 0(blank),0.02(C1),0.05(C2),0.10(C3),and 0.15 mg·L–1(C4)at a salinity of 10‰ or 40‰ for 96 h,with the salinity of 29‰ as the *** results showed that the effects of the acute salinity stimulation to survival rates of pompano between control(29‰)and lower or higher salinity for 96 h were not significant(p>0.05).However,the survival rates in each treatment were decreased with the increase of Cu2+ *** dominant factor influencing body moisture of the fish was salinity,and there was no sign that body moisture was correlated with exposure to Cu2+.The gill lamellas in high level of Cu2+ concentration(C4 treatments)were abnormal under the salinity of 40‰ and extremely curly under the salinity of 10‰.Hemorrhage in gill was observed in the two C4 *** transmission electron microscope,pillar cells in gill lamellas appeared deformed and ruptured in some areas of the epithelia in the higher concentration of Cu2+,resulting in the death of the fish due to the destruction of gill tissue,elevation of the arithmetic mean distance from water to blood,the decrease of oxygen diffusion capacity,and other physiological *** findings indicate that the pompano might suffer much more pressure when encountered with Cu2+ pollution and low salinity.

关键词： Trachinotus ovatus juvenile selective group Cu2+ toxicity salinity shock

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Variations of broad emission lines from periodicity QSOs under the interpretation of supermassive binary black holes with misaligned circumbinary broad line regions

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Research in Astronomy and Astrophysics 2021年第9期21卷 63-74页

作者： Xiang Ji jun-Qiang Ge you-jun Lu Chang-Shuo Yan CAS Key Laboratory for Computational Astrophysics National Astronomical ObservatoriesChinese Academy of SciencesBeijing 100101China School of Astronomy and Space Science University of Chinese Academy of SciencesBeijing 100049China

Quasars with periodic light curves are considered as candidates of supermassive binary black hole(BBH)*** way for further confirmations may be searching for other characteristic signatures,such as those in their broad emission lines(BELs),if any,which require a thorough understanding on the response of BELs to the BBH *** Ji et al.(2021),we have investigated the response of circumbinary broad line region(BLR)to the central active secondary black hole under the relativistic Doppler boosting(BBH-DB)and intrinsic variation(BBH-IntDB)dominant mechanisms for continuum variation by assuming the middle plane of the BLR aligned with the BBH orbital *** this paper,we explore how the BEL profiles vary when the BLR is misaligned from the BBH orbital plane with different offset angles under both the BBH-DB and BBH-IntDB *** a fixed inclination angle of the BBH orbital plane viewed in edge-on and similar continuum light curves produced by the two scenarios,increasing offset angles make the initial opening angle of the circumbinary BLR enlarged due to orbital precession caused by the BBH system,especially for clouds in the inner region,which result in Lorentzlike BEL profiles for the BBH-DB model but still Gaussion-like profiles for the BBH-IntDB model at the vertical BLR *** amplitude of profile variations decreases with increasing offset angles for the BBHDB scenario,while keeps nearly constant for the BBH-IntDB scenario,since the Doppler boosting effect is motion direction preferred but the intrinsic variation is radiated *** the circumbinary BLR is composed of a coplanar and a vertical components with their number of clouds following the mass ratio of the BBHs,then the bi-BLR features are more significant for the BBH-IntDB model that requires larger mass ratio to generate similar continuum variation than the BBH-DB model.

关键词： black hole physics quasars supermassive black holes emission lines profiles

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Characteristics of biomarker in source rocks of Linxi Formation in Taohaiyingzi region, Zhalute basin

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Chinese Journal Of Geochemistry 2015年第3期34卷 338-345页

作者： Li Liu you-jun Tang Xing-chao Jiang Key Laboratory of Exploration Technologies for Oil and Gas Resources Ministry of Education School of Earth Environment and Water Resources Yangtze University

Based on gas chromatography and gas chromatography mass spectrometry techniques, the authors researched biomarker characteristics of the Linxi Formation source rocks in the area of Taohaiyingzi, and analyzed the information and petroleum geological significance that were indicated by source of organic matter, sedimentary environment, maturity and so on. Gas chromatography peak of saturated hydrocarbons from Linxi Formation source rocks showed ‘‘the former peak'' of the single peak distribution and the C23-dominant main peak. This indicates that the main source of organic matter was mixed organic matter; Pr/Ph ratios ranged from 0.3 to 0.6, indicating a strongly reducing sedimentary *** fossil assemblages in Linxi Formation source rocks were abundant in tricyclic terpane with long side chains, had high level of gammacerane, and showed dominant distribution of C27 steranes. Gammacerane ratios range from 0.15 to 0.29, with an average of 0.19, implying that Linxi Formation hydrocarbon source rocks were formed in the environment of micro-saltwater water to half-saltwater water. The hopanes/steranes ratios are mainly between 0.6 and 1.0, with an average of 0.84, implying that bacteria and algae had almost the samecontribution to organic matter. C27 steranes abundance is high and the ratio of C27steranes/C29 steranes is 1.13,showing that algae is the main source of hydrocarbon precursors.

关键词：生物标志物烃源岩特征比值范围盆地石油地质意义气相色谱沉积环境

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Modeling rock failure using the numerical manifold method followed bythe discontinuous deformation analysis

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Acta Mechanica Sinica 2012年第3期28卷 760-773页

作者： you-jun Ning Xin-Mei An Qing Lu Guo-Wei Ma School of Manufacturing Science and Engineering Southwest University of Science and Technology621010 Mianyang China School of Civil and Environmental Engineering Nanyang Technological University639798 Singapore Singapore College of Civil Engineering and Architecture Zhejiang University 310058 Hangzhou China School of Civil and Resource Engineering University of Western Australia35 Stirling Highway Crawley WA 6009 Australia

A complete rock failure process usually involves opening/sliding of preexisting discontinuities as well as frac- turing in intact rock bridges to form persistent failure sur- faces and subsequent motions of the generated rock blocks. The recently developed numerical manifold method （NMM） has potential for modelling such a complete failure process. However, the NMM suffers one limitation, i.e., unexpected material domain area change occurs in rotation modelling. This problem can not be easily solved because the rigid body rotation is not represented explicitly in the NMM. The discontinuous deformation analysis （DDA） is specially de- veloped for modelling discrete block systems. The rotation- induced material area change in the DDA modelling can be avoided conveniently because the rigid body rotation is represented in an explicit form. In this paper, a transition technique is proposed and implemented to convert a NMMmodelling to a DDA modelling so as to simulate a complete rock failure process entirely by means of the two methods, in which the NMM is adopted to model the early fracturing as well as the transition from continua to discontinua, while the DDA is adopted to model the subsequent motion of the generated rock blocks. Such a numerical approach also im- proves the simulation efficiency greatly as compared with a complete NMM modelling approach. The fracturing of a rock slab with pre-existing non-persistent joints located on a slope crest and the induced rockfall process are simulated. The validity of the modelling transition from the NMM to the DDA is verified and the applicability of the proposed nu- merical approach is investigated.

关键词： Rock fracturing. Non-persistent joint. Rockfall Numerical manifold method Discontinuous deformationanalysis

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Syntheses of DL-threo-Thiamphenicol via Green Oxidation

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Chemical Research in Chinese Universities 2006年第5期22卷 602-605页

作者： LIU Kai Robert Franzén YU Xiao-jing ZHANG jun XU you-jun School of Pharmaceutical Engineering Shenyang Pharmaceutical University Shenyang 110016 P. R. China Institute of Materials Chemistry Tampere University of Technology Korkeakoulunkatu 8 FIN-33720 Tampere Finland

Four methyl aryl thioethers related to thiamphenicol syntheses and methyl phenyl sulfide were cleanly oxidized into methyl sulfones in high to excellent yields via catalytic green oxidation with aqueous hydrogen peroxide in combination with sodium tungstate. When the same reactions were similarly performed in the absence of the catalyst, the corresponding sulfoxides could be obtained. This viable synthetic approach for the synthesis of DL-threo-thiamphenicol is a simple procedure, which has an economic advantage in view of its application for the large-scale synthesis because it can be carried out under mild conditions.

关键词： Green oxidation Hydrogen peroxide Sodium tungstate Thiamphenicol

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