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Meteorological Services
Published in Graham D. Lees, William G. Williamson, Handbook for Marine Radio Communication, 2020
Graham D. Lees, William G. Williamson
Coast stations broadcast gale warnings when the mean wind reaches force 8 or above, or when gusts reaching 43-51 knots are expected. The warnings stay in force until amended or cancelled; however, if gale conditions persist for more than 24 hours, the warning may be reissued. The RT transmission is made at conversational speed, then repeated at dictation speed. For the High Seas of the North Atlantic, storm warnings are issued when mean wind speeds are expected to reach or exceed 48 knots, force 10 or above, or gusts reaching 48-55 knots.
Measurements of car-body lateral vibration induced by high-speed trains negotiating complex terrain sections under strong wind conditions
Published in Vehicle System Dynamics, 2018
Dongrun Liu, Zhaijun Lu, Mu Zhong, Tianpei Cao, Dong Chen, Yupu Xiong
The wind speed in this paper obtained from the railway meteorological department refers to the wind speed measured through the gale warning system of Lanzhou–Xinjiang high-speed railway. To guarantee the safe running in strong winds, a number of base stations were established to test wind speed in the continuous wind area along the Lanzhou–Xinjiang high-speed railway. The wind towers are arranged along the railway line at intervals according to the nearby topography. Considering the influence of changes in terrain changes on the wind speed, the spacing between two wind towers should be 1500–2000 m in flat terrain, and 100–200 m in complex terrain with abrupt changes. The wind towers are located 10 m from the centreline of track outside the windbreak, and each wind tower is equipped with two sets of sensors to detect wind speed and wind direction, which are 4.5–5 m higher above the track, as shown in Figure 2. Ventus-V200A ultrasonic anemoscope made by Lufft Company is adapted as the wind force monitoring equipment. It has four ultrasonic sensors to measure in all directions. The wind speed measurement range is 0–60 m/s, the sampling rate is 250 ms, and the response threshold is 0.1 m/s, which fully meets the requirements of wind speed measurement for this test [11]. Next, all the wind speeds mentioned are the mean values within 1 s when the vehicle passes the position, truly reflecting the wind speed when the train passes.
Effect of wind speed variation on the dynamics of a high-speed train
Published in Vehicle System Dynamics, 2019
Dongrun Liu, Qianxuan Wang, Mu Zhong, Zhaijun Lu, Jiabin Wang, Tianjun Wang, Siyu Lv
Therefore, based on the above engineering requirements and studies, we established a wind speed model and studied the effects of gust parameters on the dynamic performance of a high-speed train. Furthermore, we determined a wind speed range for ensuring a safe train operation considering the wind speed variation. The effect of the wind speed variation along the line on the operational safety can be determined in a timely manner with the help of the measured wind speed of the gale warning system along the line. Thereafter, a reasonable speed regulation can be carried out.