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Nonlinear dynamic analysis of a rotor/bearing/seal system

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2011年第1期12卷 46-55页

作者： Wei LI Yi YANG De-ren sheng jian-hong chen Yong-qiang CHE Department of Energy Engineering Zhejiang University Hangzhou 310027 China

In this study a new dynamic model of a rotor system is established based on the Hamilton principle and the finite element method (FEM). We analyze the dynamic behavior of the rotor system with the coupled effects of the nonlinear oil film force, the nonlinear seal force, and the mass eccentricity of the disk. The equations of the motion are solved effectively using the fourth order Runge-Kutta method in MATLAB. The dynamic behavior of the system is illustrated by bifurcation diagrams, largest Lyapunov exponents, phase trajectory diagrams, and Poincaré maps. The numerical results show that the rotational speed of the rotor, the pressure drop in the seal, the seal length, the seal clearance, and the mass eccentricity of the disk are the key parameters that significantly affect the dynamic characteristics of the rotor system. The motion of the rotor system exhibits complex types of periodic, quasi-periodic, double-periodic, multi-periodic, and chaotic vibrations. This analysis can be used to guide the design of seal parameters and to diagnose the vibration of rotor/bearing/seal systems.

关键词： Nonlinear Rotor system Hamilton principle Dynamic Finite element method (FEM)

Experimental study on piping in sandy gravel foundations considering effect of overlying clay

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Water Science and Engineering 2016年第2期9卷 165-171页

作者： Shuang Wang jian-sheng chen Hai-qing He Wen-zheng He College of Civil and Transportation Engineering Hohai University College of Earth Sciences and Engineering Hohai University

The influence of the overlying clay on the progression of piping in the sandy gravel foundation of water-retaining structures is often neglected. In order to study this influence, an experimental investigation was conducted on a laboratory-scale model. It was discovered that the critical hydraulic gradient and the area of the piping tunnel increase when the overlying clay thickens. With a thicker clay layer, erosion of the sandy gravel below the clay layer occurs later, but, once the erosion starts, the erosion rate is very high and the average velocity of water seeping through the cross-section of the sandy gravel increases rapidly due to the low deformability of the thick clay layer. Furthermore, it was found that the progression of piping is a complicated and iterative process involving erosion of fine particles, clogging of pores, and flushing of the clogged pores. Two types of erosion have been identified in the progression of piping: one causes the tunnel to advance upstream, and the other increases the depth of the tunnel. The results show that the overlying clay is an important factor when evaluating piping in sandy gravel foundations of water-retaining structures.

关键词： Piping Experimental model Sandy gravel foundation Overlying clay Clog Erosion rate

Mathematical model of burden distribution in bell-less top blast furnace

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Journal of Iron and Steel Research International 2023年第2期30卷 216-226页

作者： jian-sheng chen Hai-bin Zuo Jing-xiu Wang Qing-guo Xue Jing-song Wang State Key Laboratory of Advanced Metallurgy University of Science and Technology BeijingBeijing100083China

The burden distribution in the shaft of blast furnace is known to affect the gas distribution,heat transfer,and chemical reactions inside the ***,the internal layer structure of burden in the shaft cannot be directly ***,a mathematical model for evaluating burden profile and layer structure was established.A sensitivity analysis based on the model was implemented to elucidate the effect of some factors on the burden distribution,including the stockline height and the mass of central *** results show that the width of funnel zone widens with the increase in stockline height,and the mass percentage of ore to coke in this zone slightly ***,the mass of central coke shows a significant influence on the width of coke channel,and 2%of batch mass of coke is recommended to implement central coke charging *** model has been indirectly verified by the gas temperature in operating blast furnace and successfully applied to online evaluate burden distribution.

关键词： Blast furnace Burden distribution Mathematical model Stockline height Central coke

Estimating the Metallicity of Old Star Clusters in M33

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Chinese Journal of Astronomy and Astrophysics 2002年第2期2卷 127-132页

作者： Jun Ma Xu Zhou Hong Wu jian-sheng chen Zhao-Ji jiang Sui-jian Xue Jin Zhu National Astronomical Observatories Chinese Academy of SciencesBeijing 100012

Based on the method proposed by Kong et al. and on the multi-color spectrophotometry by Ma et al., we estimate the metallicities of 16 old star clusters in the nearby spiral galaxy M33, ten of which are halo globular clusters. These old clusters are all metal poor, the range of metallicity ([Fe/H]) is from-0.14 to-2.12. In general, our results are consistent with those derived by other methods, such as integrated spectra and photometry, and our study confirms the reliability of the method of Kong et al.

关键词： galaxies individual(M33)-galaxies evolution-galaxies star clusters

Effect of quaternary basicity on softening-melting behavior of primary slag based on magnesium flux pellet

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Journal of Iron and Steel Research International 2022年第8期29卷 1185-1193页

作者： Kai-kai Bai Hai-bin Zuo Wen-guo Liu Jing-song Wang jian-sheng chen Qing-guo Xue State Key Laboratory of Advanced Metallurgy University of Science and Technology BeijingBeijing 100083China

It is generally accepted that the softening-melting properties of ferrous burden play a vital role in optimizing the shape and position of cohesive *** effect of quaternary basicity and atmosphere on softening,melting and permeation temperatures of primary slag based on magnesium flux pellet was investigated by visualization *** mechanisms were analyzed utilizing thermodynamic calculation,X-ray diffraction analysis and electron probe *** results indicated that the softening and melting temperatures of oxide samples increased by approximately 120℃with increasing quaternary basicity from 0.3 to 1.2 owing to the formation of slag phases with high melting point and solid ***,the difference between softening and melting temperatures decreased from 21 to 11℃.The permeation temperature was not affected by the quaternary basicity and fluctuated around a level of 1250 C,given that the permeation temperature depends on the wettability between slag and coke *** the other hand,as the ratios of CO/CO_(2) varied from 3/7 to 7/3,there were no significant differences in either the softening or melting temperatures,whereas the permeation temperature was increased from 1239 to 1271℃ since the reduction of FeO-bearing phases to solid Fe could decrease the wettability between slag and coke bed.

关键词： Magnesium flux pellet Primary slag Quaternary basicity CO/CO_(2)ratio Cohesive zone Softening-melting Behavior

Improving mathematical model of burden distribution and correcting chute angle to cope with fluctuation of stock line

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Journal of Iron and Steel Research International 2024年第2期31卷 342-356页

作者： jian-sheng chen Wen-guo Liu Hao Guo Wang Ding Qing-guo Xue Jing-song Wang Hai-bin Zuo State Key Laboratory of Advanced Metallurgy University of Science and Technology BeijingBeijing100083China MCC Capital Engineering&Research Incorporation Limited Beijing100176China Hunan Valin Xiangtan Iron and Steel Co. Ltd.Xiangtan411101HunanChina

Accurate evaluations of the burden distribution are of critical importance to stabilize the operation of blast *** mathematical model and discrete element method(DEM)are two attractive methods for predicting burden *** on DEM,the initial velocities of the pellet,sinter,and coke were calculated,and the velocity attenuations of the above three particles between the burden and the chute were *** initial velocity and velocity attenuation were applied to a mathematical model for improving the ***,based on the improved model,a scheme for rectifying the chute angles was proposed to address the fluctuation of the stock line and maintain a stable burden *** validity of the scheme was confirmed via a stable burden distribution under different stock *** mathematical model has been successfully applied to evaluate the online burden distribution and cope with the fluctuation of the stock line.

关键词： Burden distribution Mathematical model Discrete element method Velocity attenuation Stock line fluctuation

Positions and Spectral Energy Distributions of 41 Star Clusters in M33

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Chinese Journal of Astronomy and Astrophysics 2002年第3期2卷 197-206页

作者： Jun Ma, Xu Zhou, jian-sheng chen, Hong Wu, Zhao-Ji jiang, Sui-jian Xue and Jin ZhuNational Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012 National Astronomical Observatories Chinese Academy of Sciences Beijing 100012

We present accurate positions and multi-color photometry for 41 star clusters detected by Melnick & D'odorico in the nearby spiral galaxy M33 as a part of the BATC Color Survey of the sky in 13 intermediate-band filters from 3800 to 10 000 A. The coordinates of the clusters are found from the HST Guide Star Catalog. By aperture photometry, we obtain the spectral energy distributions of the clusters. Using the relations between the BATC intermediate-band system and UBVRI broadband system, we derive their V magnitudes and B - V colors and find that most of them are blue, which is consistent with previous findings.

关键词： galaxies: individual (M33) - galaxies: evolution - galaxies: star clusters

Variable stars in the field of open cluster NGC 2126

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Research in Astronomy and Astrophysics 2009年第7期9卷 791-802页

作者： Shun-Fang Liu Zhen-Yu Wu Xiao-Bin Zhang jiang-Hua Wu Jun Ma Zhao-Ji jiang jian-sheng chen Xu Zhou National Astronomical Observatories Chinese Academy of Sciences Beijing 100012 China Graduate University of Chinese Academy of Sciences Beijing 100049 China

We report the results of a time-series CCD photometric survey of variable stars in the field of open cluster NGC 2126. In about a one square degree field covering the cluster, a total of 21 variable candidates are detected during this survey, of which 16 are newly found. The periods, classifications and spectral types of 14 newly discovered variables are discussed, which consist of six eclipsing binary systems, three pulsating variable stars, three long period variables, one RS CVn star, and one W UMa or δ Scuff star. In addition, there are two variable candidates, the properties of which cannot be determined. By a method based on fitting observed spectral energy distributions of stars with theoretical ones, the membership probabilities and the fundamental parameters of this cluster are determined. As a result, five variables are probably members of NGC 2126. The fundamental parameters of this cluster are determined as： metallicity to be 0.008 Z, age log（t） = 8.95, distance modulus （m - M）0 = 10.34 and reddening value E（B - V） = 0.55 mag.

关键词： open clusters: individual (NGC 2126) - stars: variables (general) - bina- ties: general

Old stellar population synthesis:new age and mass estimates for Mayall II = G1

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Research in Astronomy and Astrophysics 2009年第6期9卷 641-652页

作者： Jun Ma Richard de Grijs Zhou Fan Soo-Chang Rey Zhen-Yu Wu Xu Zhou jiang-Hua Wu Zhao-Ji jiang jian-sheng chen Kyungsook Lee Sangmo Tony Sohn National Astronomical Observatories Chinese Academy of Sciences Beijing 100012 China Department of Physics ＆ Astronomy The University of Sheffield Hicks Building Hounsfield Road Sheffield S3 7RH UK Graduate University Chinese Academy of Sciences Beijing 100049 China Department of Astronomy and Space Science Chungnam National University Daejeon 305-764 Korea Center for Space Astrophysics Yonsei University Seoul 120-749 Korea California Institute of Technology MC 405-47 1200 E. California Boulevard Pasadena CA 91125

Mayall Ⅱ = G1 is one of the most luminous globular clusters （GCs） in M31. Here, we determine its age and mass by comparing multicolor photometry with theoretical stellar population synthesis models. Based on far- and near-ultraviolet GALEX photometry, broad-band UBVRI, and infrared JHKs 2MASS data, we construct the most extensive spectral energy distribution of G 1 to date, spanning the wavelength range from 1538 to 20 000A. A quantitative comparison with a variety of simple stellar population （SSP） models yields a mean age which is consistent with G1 being among the oldest building blocks of M31 and having formed within ～1.7 Gyr after the Big Bang. Irrespective of the SSP model or stellar initial mass function adopted, the resulting mass estimates （of order 10^7M⊙） indicate that GI is one of the most massive GCs in the Local Group. However, we speculate that the cluster＇s exceptionally high mass suggests that it may not be a genuine GC. Our results also suggest that G1 may contain, on average, （1.65±0.63） × 10^2L⊙ far-ultraviolet-bright, hot, extreme horizontal-branch stars, depending on the adopted SSP model. In addition, we demonstrate that extensive multi-passband photometry coupled with SSP analysis enables one to obtain age estimates for old SSPs that have similar accuracies as those from integrated spectroscopy or resolved stellar photometry, provided that some of the free parameters can be constrained independently.

关键词： galaxies individual (M31) -- galaxies star clusters -- galaxies stellar content