An analysis of the self-excited torsional vibration of high-speed train drive system

Kun Xu,Jing Zeng,Lai Wei 대한기계학회 2019 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.33 No.3

In this paper, a simplified torsional vibration model of drive system with three degrees of freedom is established, and the elasticity of wheelset is considered. In addition to the same wheel-rail adhesion condition for the two wheels, the different wheel-rail adhesion conditions for the two wheels have been considered for the first time, and the mechanism of the vibration forms is explained from the viewpoint of energy. The nonlinear system is linearized at the origin (equilibrium position), and the critical stability curve of the linearized system is drawn according to the eigenvalues of the linearized system in the state space. The results show that the vibration forms of the system are mainly determined by the relationships between the average creep rate and the critical creep rate of the wheel driven directly by motors. When the resistance moments do positive work on the system, they input energy to the system, and the responses do not tend to the origin and produce self-excited vibration. When the resistance moments do negative work on the system, they dissipate energy to system, and the responses tend to the origin. For the linearized system at the origin, the system is more stable at the origin when following factors occur, a gentler negative slope of the adhesion curve, a faster speed, a lighter wheel load, and a larger the moment of inertia of wheels.

An Iris Localization Algorithm based on Morphological Processing

Kun Yu,Zeyu Xu,Lixin Xu 보안공학연구지원센터 2015 International Journal of Security and Its Applicat Vol.9 No.3

To improve the speed of iris localization, an iris localization algorithm based on the morphological processing is proposed with fast speed. Firstly, pupil area is segmented from eye image by thresholding, to remove eyelash noise and other noises from binaryzation pupil area by morphological open operation. Then, a series of structure element of radius increasing is used to make morphological erode operation on pupil area to localize roughly the inner boundary of the iris. Finally, calculus operator is employed to accurately localize the inner and outer iris boundary. 108 iris images from CASIA (Version 1.0) iris database are used to do iris localization experiments. The localization accurate rate of the proposed algorithm, calculus operator and hough transform is 97.2%, 90.3% and 92.1% respectively. Experiment results have showed that the proposed algorithm has a high performance on speed and precision with strong robustness to the different quality iris images.

Diversity-Multiplexing Tradeoff Analysis of Wireless Multiple-Antenna Cooperative Systems in General Fading Channels

( Kun Xu ),( Yuanyuan Gao ),( Xiaoxin Yi ),( Yajun Zhang ) 한국인터넷정보학회 2012 KSII Transactions on Internet and Information Syst Vol.6 No.11

In this paper, diversity-multiplexing tradeoff (DMT) of three-user wireless multiple-antenna cooperative systems is investigated in general fading channels when half-duplex and decode-and-forward relay is employed. Three protocols, i.e., adaptive protocol, receive diversity protocol, and dual-hop relaying protocol, are considered. The general fading channels may include transmit and/or receive correlation and nonzero channel means, and are extensions of independent and identically distributed Rayleigh or Rician fading channels. Firstly, simple DMT expressions are derived for general fading channels with zero channel means and no correlation when users employ arbitrary number of antennas. Explicit DMT expressions are also obtained when all users employ the same number of antennas and the channels between any two users are of the same fading statistics. Finally, the impact of nonzero channel means and/or correlation on DMT is evaluated. It is revealed theoretically that the DMTs depend on the number of antennas at each user, channel means (except for Rayleigh and Rician fading statistics), transmit and/or receive correlation, and the polynomial behavior near zero of the channel gain probability density function. Examples are also provided to illustrate the analysis and results.

Effects of Mulching with Straw on the Photosynthetic Characteristics of Ginger

Kun Xu,Lei Wang 한국원예학회 2006 한국원예학회 기타간행물 Vol.- No.-

Multiple Temperature Model for Near Continuum Flows

Kun Xu,Hongwei Liu,Jianzheng Jiang 대한기계학회 2007 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.21 No.9

Novel Determination of Wheel-Rail Adhesion Stability for Electric Locomotives

Kun Xu,Guoqing Xu,Chunhua Zheng 한국정밀공학회 2015 International Journal of Precision Engineering and Vol. No.

Monitoring the wheel-rail adhesion state and maintaining the stability are the key issues to ensure the safety of locomotives withincreasing running speed nowadays. In this paper, a novel methodology is proposed to determine the wheel-rail adhesion stability. It is proved that when the adhesion state is in the unstable region, the transmitting factor which is defined as the ratio of the adhesionforce in the wheel drive force is negative. Based on this principle, we propose a novel adhesion stability detector via measuring thewheel drive torque and the wheel rotational speed. It is free from measuring or determining the chassis speed, creep ratio, and optimalcreep ratio, which are usually difficult to obtain in practical applications. In addition, the proposed methodology can evaluate theadhesion state dynamically regardless of the specific wheel-rail conditions. Numerical simulations are carried out to validate itseffectiveness.

Mortality Characteristic and Prediction of Nasopharyngeal Carcinoma in China from 1991 to 2013

Xu, Zhen-Xi,Lin, Zhi-Xiong,Fang, Jia-Ying,Wu, Ku-Sheng,Du, Pei-Ling,Zeng, Yang,Tang, Wen-Rui,Xu, Xiao-Ling,Lin, Kun Asian Pacific Journal of Cancer Prevention 2015 Asian Pacific journal of cancer prevention Vol.16 No.15

Background: To analyze the mortality distribution of nasopharyngeal carcinoma in China from 1991 to 2013, to predict the mortality in the ensuing five years, and to provide evidence for prevention and treatment of nasopharyngeal carcinoma. Materials and Methods: Mortality data for Nasopharyngeal Carcinoma in China from 1991 to 2013 were used to describe its epidemiological characteristics, such as the change of the standardized mortality rate, sex and age differences, urban-rural differences. Trend-surface analysis was used to study the geographical distribution of the mortality. Curve estimation, time series, gray modeling, and joinpoint regression were used to predict the mortality for the ensuing five years in the future. Results: In China, the standardized mortality rate of Nasopharyngeal Carcinoma increased with time from 1996, reaching the peak values of $1.45/10^5$ at the year of 2002, and decreased gradually afterwards. With males being 1.51 times higher than females, and the city had a higher rate than the rural during the past two decades. The mortality rate increased from age 40. Geographical analysis showed the mortality rate increased from middle to southern China. Conclusions: The standardized mortality rate of Nasopharyngeal Carcinoma is falling. The regional disease control for Nasopharyngeal Carcinoma should be focused on Guangdong province of China, and the key targets for prevention and treatment are rural men, especially after the age of 40. The mortality of Nasopharyngeal Carcinoma will decrease in the next five years.

The Changes of Carbon and Nitrogen Nutrition during Growth of Ginger

Kun Xu,Hua Su 한국원예학회 2006 한국원예학회 기타간행물 Vol.- No.-

Studies on the Photosynthetic Characteristics of Chinese Mahogany

Kun Xu 한국원예학회 2006 한국원예학회 기타간행물 Vol.- No.-

Effects of Fermented Rapeseed Meal on Growth Performance and Serum Parameters in Ducks

Fazhi, Xu,Lvmu, Li,Jiaping, Xu,Kun, Qian,Zhide, Zhang,Zhangyi, Liang Asian Australasian Association of Animal Productio 2011 Animal Bioscience Vol.24 No.5

A trial was performed to study the effects of feeding a diet containing solid-state fermentation rapeseed meal (FRSM) replaced soybean meal (SBM) on growth performance and serum biochemistry parameters of ducks and then to determine the appropriate proportion of soybean meal replacement. The 75% rapeseed meal and 25% blood meal were mixed and inoculated with the Lactobacillus plantarum and Bacillus subtilis. Over the 21-day fermentation, isothiocyanates were reduced from 72.7 to 14.1 mmol/kg. A total of 1,280 fifteen-day-old Cherry Valley ducks were randomly allocated into 4 dietary treatments, 4 replicate groups of 80 ducks each for a 30-day feeding trial. In four treatment groups, fermentation rapeseed meal replaced soybean meal at 0, 33, 67 or 100%, respectively. Results showed that feed intake of ducks fed 100% FRSM was greater (p<0.05) than SBM and partial FRSM in both the finishing period (31-45 d) and entire feeding period (15-45 d). Daily gain increased gradually in the three treatment groups with augmenting FRSM over in the whole study period. In the growing period (15-30 d), compared with the SBM group, phosphorus and calcium content in serum from the FRSM group was improved (p<0.05). Total protein concentration was lower in ducks fed 100% FRSM than SBM and 33% FRSM (p<0.05). Concentrations of IgM were dramatically higher for animals fed 100% FRSM than in the SBM, 33% FRSM and 67% FRSM groups. In the finishing trail stage (31-45 d), only serum IgG content in 100% FRSM group was improved (p<0.05). Therefore, rapeseed meal fermented with Lactobacillus plantarum and Bacillus subtilis is a promising alternative protein source and fermented rapeseed meal can completely replace soybean meal in duck diet and potentially reduce the cost of duck production.