THE INSTABILITIES OF ACCRETION DISKS WITH RADIAL ADVECTION

WU XUE-BING The Korean Astronomical Society 1996 Journal of The Korean Astronomical Society Vol.29 No.suppl1

The local instabilities of accretion disks were extensively studied, with the considerations of radial advection, thermal diffusion and different disk geometry, dominated pressure and optical depth. Two inertial-acoustic modes in a geometrically thin, radiative cooling dominated disk depart from each other if very little advection is included. A geometrically slim, advection-dominated disk is found to be always stable if it is optically thin. However, if it is optically thick, the thermal diffusion has no effect on the stable viscous mode but has a significant contribution to enhance the thermal instability.

Black Hole Mass and Accretion Rate of Active Galactic Nuclei

Xue-Bing Wu,F.K. Liu,J.L. Han,M.Z. Kong,R. Wang 한국물리학회 2006 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.49 No.4

The determination of the central black hole mass is crucial to the understanding of active galactic nuclei physics. In this paper, we brie°y review some methods that are currently used to estimate the black hole mass of AGNs. Particularly, we demonstrate the importance of two correlations: one between the black hole mass and the stellar velocity dispersion and the other one between the broad line region (BLR) size and the optical continuum luminosity. Besides applying these relations in deriving the black hole masses of various types of AGNs, we also employ the fundamental plane of elliptical galaxies to estimate the central velocity dispersions of AGN host galaxies, and then the black hole masses of AGNs, including BL Lac objects. In addition, we derive another empirical relation between the BLR size and the H. emission line luminosity from AGNs with the BLR size measured by reverberation mapping studies, and we argue that more accurate black hole masses of extremely radio-loud AGNs can be obtained with it than by using the usual R ¡ L 5100ºA relation because of the jet contribution to the optical continuum. Finally, we point out that black hole mass estimation is very much helpful in determining the accretion rate and in understanding the accretion process in AGNs.

Experimental study on creep behavior of fly ash concrete filled steel tube circular arches

Wu T. Yan,Bing Han,Jin Q. Zhang,Hui B. Xie,Li Zhu,Zhong J. Xue 국제구조공학회 2018 Steel and Composite Structures, An International J Vol.27 No.2

Fly ash can significantly improve concrete workability and performance, and recycling fly ash in concrete can contribute to a cleaner environment. Since fly ash influences pozzolanic reactions in concrete, mechanical behaviors of concrete containing fly ash differ from traditional concrete. Creep behaviors of fly ash concrete filled steel tube arch were experimentally investigated for 10% and 30% fly ash replacement. The axes of two arches are designed as circular arc with 2.1 m computed span, 0.24 m arch rise, and their cross-sections are all in circular section. Time dependent deflection and strain of loading and mid-span steel tube were measured, and long term deflection of the model arch with 10% fly ash replacement was significantly larger than with 30% replacement. Considering the steel tube strain, compressive zone height, cross section curvature, and internal force borne by the steel tube, the compressive zone height and structural internal forces increased gradually over time due to concrete creep. Increased fly ash content resulted in more significant neutral axis shift. Mechanisms for internal force effects on neutral axis height were analyzed and verified experimentally.

Inward and Outward Starburst Feedbacks and Growth of Supermassive Black Holes

Bing-Xiao Xu,Xue-Bing Wu 한국물리학회 2006 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.49 No.4

Based on the major merger scenario we propose a simple model to investigate the relation between the starburst and the central active galactic nuclei (AGN). We argue that the momentum feedback from the starburst rather than from the central black hole (BH) plays the most important role in the main growth stage of both the BH and the bulge. We suggest that for small scale, the momentum feedback from the starburst may exist in two directions. The outward starburst feedback can blow some gas away to halt the star formation activity, and the growth of the BH is regulated by the inward starburst feedback. The final BH mass is directly related to the maximum star formation rate based on this scenario, and such a relation can be used to derive the MBH. and MBH.Mbulge relations, which are consistent with recent observations and simulations. Our result suggests that the BH undergoes its main growth in an obscured environment, which may be just the “pre-quasar” phase, as some authors previously argued.

Machining Surface Quality Analysis of Aluminum Alloy Thin-Walled Parts in Aerospace

Dai Bing,Yu Guang-bin,Guan Yan-qi,Shao Jun-peng,Guan Yan-qi,Wu Xue-mei,Liu Yu-xin 보안공학연구지원센터 2015 International Journal of Security and Its Applicat Vol.9 No.11

There are many key parts in the field of aerospace with aluminum alloy thin-walled parts, the problem of breaking the low efficiency in production that’s also followed. There will be a lot of deformation in processing because of its poor rigidity, poor process, which will lead to low processing efficiency. It is of great significance to improve the machining efficiency of the aluminum alloy thin-walled parts, and a series of analysis of the surface quality of aluminum alloy thin-walled parts there are carried out clamping, cutting tools, take the knife route so on, and the problems of low machining efficiency and poor surface quality are solved.

Incidence of the Rice Root-Knot Nematode, Meloidogyne graminicola, in Guangxi, China

Man Luo,Bing Xue Li,Han Yan Wu 한국식물병리학회 2020 Plant Pathology Journal Vol.36 No.3

Root-knot nematodes (Meloidogyne spp.) are the most destructive group of plant-parasitic nematodes. Plants infected by Meloidogyne spp. develop above-ground symptoms, stunting, yellowing, nutrient deficiencies, and gall formations with typical hook-shaped root tips. Infected plants experience yield losses. During 2018-2019 survey, leaf chlorosis rice plants were found in 206 fields of 67 counties in Guangxi, China, around 30 days after transplanting. Galls and hooked tips on the roots and pear-shaped females were observed. About 32.04% of fields were infested with the nematode. The nematodes were identified as Meloidogyne graminicola base on morphological and molecular analysis. To the best of our knowledge, this is the first report of M. graminicola on rice plants in Guangxi, China. The results of this study urge the discovery of resistant cultivars and the development of management strategies.

AN ULTRA-LUMINOUS QUASAR AT <i>z</i> = 5.363 WITH A TEN BILLION SOLAR MASS BLACK HOLE AND A METAL-RICH DLA AT <i>z</i> ∼ 5

Wang, Feige,Wu, Xue-Bing,Fan, Xiaohui,Yang, Jinyi,Cai, Zheng,Yi, Weimin,Zuo, Wenwen,Wang, Ran,McGreer, Ian D.,Ho, Luis C.,Kim, Minjin,Yang, Qian,Bian, Fuyan,Jiang, Linhua IOP Publishing 2015 ASTROPHYSICAL JOURNAL LETTERS - Vol.807 No.1

<P>We report the discovery of an ultra-luminous quasar J030642.51+185315.8 (hereafter J0306+1853) at redshift 5.363, which hosts a supermassive black hole with M-BH = (1.07 +/- 0.27) x 10(10) M-circle dot. With an absolute magnitude M-1450 = -28.92 and a bolometric luminosity L-bol similar to 3.4 x 10(14) L-circle dot, J0306+1853 is one of the most luminous objects in the early universe. It is not likely to be a beamed source based on its small flux variability, low radio loudness, and normal broad emission lines. In addition, a z = 4.986 damped Ly alpha system (DLA) with [M/H] = -1.3 +/- 0.1, among the most metal-rich DLAs at z greater than or similar to 5, is detected in the absorption spectrum of this quasar. This ultra-luminous quasar puts strong constraints on the bright end of the quasar luminosity function and massive end of the black hole mass function. It will provide a unique laboratory for the study of BH growth and the co-evolution between a BH and the host galaxy with multi-wavelength follow-up observations. The future high-resolution spectra will give more insight into the DLA and other absorption systems along the line of sight of J0306+1853.</P>

Vibration Isolation of Extended Ultra-high Acceleration Macro-micro Motion Platform Considering Floating Stator Stage

Lufan Zhang,Xue-li Li,Jiwen Fang,Yunhao Lv,Bing Ma,Jun Wu,Hu Li 한국정밀공학회 2019 International Journal of Precision Engineering and Vol.20 No.8

It is a limitation for rapid development of microelectronics manufacturing industry to hardly overcome the acceleration limitation of macro–micro motion platform. The paper presents an extended ultra-high acceleration macro–micro motion platform to investigate breakthrough of acceleration limitation with driving modes “macro + micro + macro” (MMM). In the proposed platform, the number of the pair of VCMs was defined as n. Under ultra-high acceleration, floating stator stage is suggested to isolate the vibration and obtain superior performance of the platform. Its theoretical analyses including natural frequency analysis, transient response analysis and frequency response analysis are performed to verify vibration isolation of floating stator stage applied in the extended ultra-high acceleration macro–micro motion platform. The change trends and sensitivities of related objective functions incorporating vibration transmissibility, settling time and the maximum stroke of stator’s motion are explored with their related parameters, and their multi-objective optimization designs are carried out to achieve superior performances of different extended platforms. Moreover, one case is performed when n = 1. Its theoretical analyses, change trends and sensitivities are investigated. The superior performance of the platform is obtained to realize vibration isolation by multi-objective optimization. And its experiment of vibration isolation is also testified finally. The results provide a theoretical and technical basis on microelectronics manufacturing equipment upgrading and manufacturing rapid development.

Optimization design research of air flow distribution in vertical radial flow adsorbers

Yao Li,Haiqing Si,Bing Wang,Lu Xue,Xiaojun Wu 한국화학공학회 2018 Korean Journal of Chemical Engineering Vol.35 No.4

Non-uniform flow distribution usually exists in a vertical radial flow adsorber, which significantly decreases the utilization of adsorbents. We adopted numerical simulation methods based on the ANSYS Fluent 15.0 software to study the flow pattern in vertical radial flow adsorber, where programs of user-defined functions (UDF) were set up to interpret component equation, momentum equation and energy equation. To solve the problem of non-uniform air distribution, the relationship between the radial pressure drop across the bed and the ratio of cross-sectional area of the central pipe to that of the annular channel was studied, and optimization design of the distributor inserted in the central channel was given by parametric method at the same time. Through comparative analysis in the given experimental condition, the uniformity reached about 99.1% and the breakthrough time extended from 564 s to 1,175 s under the present optimized design method.

Pretreatment Thrombocytosis as a Prognostic Factor in Women with Gynecologic Malignancies: a Meta-analysis

Yu, Min,Liu, Lei,Zhang, Bing-Lan,Chen, Qi,Ma, Xue-Lei,Wu, Yu-Ke,Liang, Chun-Shui,Niu, Zhi-Min,Qin, Xin,Niu, Ting Asian Pacific Journal of Cancer Prevention 2012 Asian Pacific journal of cancer prevention Vol.13 No.12

Background: This study was performed to analyze the prognostic implications of pretreatment or preoperative thrombocytosis in women with gynecologic malignancies. Material and Methods: We surveyed 2 medical databases, PubMed and EMBASE, to identified all relevant studies. A total of 14 (n=3,490) that evaluated the link between thrombocytosis and 5-year survival were included. REVMAN version 5.1 was used for our analysis and publication bias was evaluated using the Begg's funnel plot and tested by STATA 11.0. Risk ratios (RRs) with 95% confidence intervals (CIs) generated by the random effect model were used to assess the strength of any association. Results: 709(20.3%) of the 3,490 patients exhibited thrombocytosis (platelet counts > $400{\times}10^9/L$) at primary diagnosis, and their mortality was 1.62-fold higher compared with the others (RR=1.62, 95%CI=[1.28-2.05], p<0.0001). Thrombocytosis failed to have a stronger effect on the survival of advanced patients of stages III to IV in our study (n=478, RR=1.29, 95% CI=[1.13-1.48], p=0.0003), nor in women with cervical cancer in stage IB (n=1371, RR=1.73, 95% CI=[1.71-2.58], p=0.007). In addition, when adjusted for different carcinoma, it was associated with worse prognosis for all except the ones with vulvar cancer (n=201, RR=0.43, 95% CI=[0.14-1.29], p=0.13). Conclusions: This meta-analysis indicated that thrombocytosis might be associated with a worse prognosis for patients with gynecologic malignancies but without specificity or sensitivity for the ones in advanced stage. When adjusted for different gynecologic malignancies, it showed a significant effect on survival of all except vulvar cancers.