Cai Z.,Tsinghua University |
Zhao H.,Tsinghua University |
Lu A.,Tsinghua University |
Pan J.,Tsinghua University |
And 2 more authors.
Zhongguo Tiedao Kexue/China Railway Science | Year: 2011
To improve the control accuracy for the perceived level-straight quality of the welded rail joints after the heat treatment, tests were carried out to analyze the variations of the arch height and the residual stress of the welded joints with actual production technique and different supporting conditions 20 hours and 30 days respectively after welding. The results indicate that the arch height of the 2 m long welded rail joint decreases about 0.1 mm during the cooling of the rail top from 55 to 25 °C. The deformations are similar under three different supporting conditions, including no gravity effect by laying down, decreasing arch height by supporting two ends and increasing arch height by supporting the joint middle. Compared with the influence of temperature, the arch variations caused by different supporting conditions are smaller by several times, even after 30 days. The residual stresses of the rail top and bottom are in compressive states and the stress values are from -300 to -150 MPa. There is no obvious stress change under different supporting conditions after 30 days laying at room temperature. Thus, to lay the welded rail joints for 8~10 hours after the heat treatment can meet the requirements for the follow-up working procedures, such as the rectification and exact grinding in practical production.
Pang M.,Beijing Jiaotong University |
Jiang W.,Beijing Jiaotong University |
Li J.,Beijing Railway Administration
ICEIE 2010 - 2010 International Conference on Electronics and Information Engineering, Proceedings | Year: 2010
China Train Control System level 3 (CTCS-3) transmits bi-directional track-train data via Global System Mobile for Railway (GSM-R) network, and GSM-R network should provide secure wireless environment to ensure train operation safety. GSM-R network handoff will cause a brief interruption of communication. If a train control message is on transmission during this interruption time, some message data units may be erroneously transmitted during the transmission interference and must be corrected by re-transmission. These re-transmissions result in a delay. This paper analysis's the message transfer mechanism, summarizes some factors influence on the message of Movement Authority (MA) transfer delay during a handoff interference, obtains values of transfer delay of MA affected by handoff, and at last verifies that recovery period of GSM-R network required in QoS specification can meet the needs of train control data transmission. © 2010 IEEE.
Shen W.-J.,Beijing Railway Administration |
Liu C.-L.,Southwest Jiaotong University |
Liu C.-H.,Taiyuan Railway Administration |
Li X.-J.,Beijing Railway Administration
Journal of Railway Engineering Society | Year: 2013
Research purposes: The top and bottom supporting ropes of the traditional passive protection systems are connected to the steel column by binding, and its guarding effect is not perfect because the structural style and load bearing of the system are unreasonable, the system's transmission property of the impact force is poor, the stress is concentrated easily when it is impacted by the falling rock and the steel column is easily bended and deformed. The separated passive protective screen overcomes the shortcomings of the traditional passive protective system and it has good protection property against the mountain dangerous rock. Research conclusions: The calculation and test results show that the various members of the separated passive protective screen can bear the load more evenly and reasonably because the screen is separated with the steel column due to the special design of the supporting ropes connection with the steel column. When holding up the falling rocks, the steel ropes can move freely. In this way, the stress concentration can be reduced, the impact force on the steel column can be cut, the transmission property of the impact force can be enhanced, the protective property can be improved, the cost can be saved and the maintenance works can be reduced. This method can be widely used in protective works for the railway slope.
Shi H.,China Academy of Railway Sciences |
Xu X.,Beijing Railway Administration |
Guo H.,Beijing Railway Administration |
Qian J.,U.S. Center for Disease Control and Prevention |
And 5 more authors.
Zhongguo Tiedao Kexue/China Railway Science | Year: 2015
Fourteen train numbers in operation were selected from five vehicle types of Beijing-Shanghai and Wuhan-Guangzhou passenger dedicated lines. Such indexes as the interior thermal environment, air quality, transient pressure, noise, vibration and illumination during the peak passenger flow period in winter and summer were tested. Meanwhile, a questionnaire survey on ride comfort was conducted among 6210 passengers. According to passengers' feelings and the evaluation of interior environment, the technical conditions for the interior environmental of high speed EMU were studied. Results showed that the priority for the concerns of high speed EMU passengers on the influencing factors of their ride comfort were noise, transient pressure, undesirable odor, toilet facilities, temperature, vibration, seat width, air freshness, foot space and vehicle interior cleanliness. The appropriate technical conditions for the interior environment of high speed EMU are suggested as follows. The interior temperature in winter should be 22~24℃ in North China and 19~22℃ in South China, while in summer, it should be 25~27℃ in North China and 26~28℃ in South China. The air quality inside should be: CO2≤0.15%, TVOC 0.8~1 mg·m-3, HCHO≤0.1 mg·m-3, NH3≤0.2 mg·m-3, PM10≤0.15 mg·m-3, CO≤5 mg·m-3, total bacterial count≤2 500 cfu·m-3, O2≥20% and negative ion≥300 N·cm-3. The fresh air volume per person should be 30 m3·h-1 and 25 m3·h-1 for the first class and the second class cars respectively. Thus the comprehensive evaluation index of the air quality can reach level 2. The maximum change rate of the interior transient pressure in plain area should be 0.3 kPa·s-1 and 0.8 kPa·(3 s)-1, in mountainous area should be 0.2 kPa·s-1 and 0.5·(3 s)-1. The interior noise should be less than or equal to 65 dB(A) and 68 dB(A) respectively in the first class car and the second class car when the train speed is less than or equal to 250 km·h-1, while less than or equal to 68 dB(A) and 70 dB(A) respectively in the first class car and the second class car when the train speed is greater than or equal to 250 km·h-1. The interior vertical, longitudinal and lateral vibration acceleration should be less than or equal to 0.50, 0.38 and 0.38 m·s-2 respectively and the vibration acceleration vector should be less than or equal to 0.9 m·s-2. The interior illumination should be greater than or equal to 200 lx for the first class car and cushioned car, and greater than or equal to 150 lx for the second class car. ©, 2015, Chinese Academy of Railway Sciences. All right reserved.