【正文】 on 193, 295–305 (1996) [3] Harrison, ., Thompson, ., Jones, .: The calculation of noise from railway viaducts and bridges. Proc. Institution Mechanical Engineers, Part F (Journal of rail and rapid transit) 214, 125–134 (2021) [4] Thompson, ., Hemsworth, B., Vincent, N.: Experimental validation of the TWINS prediction program for rolling noise, part 1: Description of the model and method. Journal of Sound and Vibration 193, 123–135 (1996) [5] Thompson, ., Jones, .: A review of the modelling of wheel/rail noise method. Journal of Sound and Vibration 231(3), 519–536 (2021) [6] Bewes, O., Thompson, ., Jones, .: Calculation of noise from railway bridges: The mobility of beams at high frequencies. Structural dynamics: Recent advances. In: Proceedings of the 8th International conference, Institute of Sound and Vibration Research, Southampton, (paper 64 on CD ROM) July 14–16 (2021) [7] Jones, ., Thompson, .: Acoustic analysis of Burgdorf bridge, ISVR contract report no 06/03, University of Southampton (2021) [8] Jones, ., Thompson, ., Diehl, .: The use of decay rates to analyse the performance of railway track in rolling noise generation. Journal of Sound and Vibration 293(3–5), 485–495 (2021) [9] Janssens, ., Dittrich, ., de Beer, ., Jones, .: Railway noise 畢業(yè)設(shè)計(jì)外文文獻(xiàn)及譯文 12 measurement method for passby noise, total effective roughness, transfer functions and track spatial decay. Journal of Sound and Vibration 293(35), 1007–1028 (2021) [10] Bouvet, P., Vincent, N., Coblenz, A., Demilly, F.: Optimisation of resilient wheels for rolling noise control. Journal of Sound and Vibration 231(3), 765–777 (2021) [11] Muff, W., Grolimund amp。 , after, (a) north track。, measured after, ──, predicted before。?, measured before。 (b) south track ( to the side, above the rail head and 25m to the side, 2m above the rail head. These were all in a plane 6m from one end of the bridge. An additional measurement was made in the position adjacent to the track at grade. The details of the measurements can be found in a report [11] for Swiss Railways. Both freight and passenger trains were measured. Only freight trains fully equipped with cast iron brakes are included. All passenger trains were either equipped with positeblock or disc brakes. All passenger trains stopped at the nearby station of Burgdorf resulting in a large range of velocities and some changes of velocity (up to20% in some cases) during measurement. 畢業(yè)設(shè)計(jì)外文文獻(xiàn)及譯文 8 4 Results and Discussion Fig. 4 presents the measurements and predictions for the freight trains for the north and south tracks before and after the installation of the resilient baseplates. Fig. 5 presents the corresponding measurement results for the passenger trains. No predictions were made for the passenger trains. The measurements are the average of freight trains travelling between 66 and 72km/hr in each case. The predictions are the nearest available at 80km/hr. It can be seen that both baseplate types perform similarly resulting in 5 to 10dB reduction of noise in the 80Hz to 400Hz onethird octave frequency bands. However, around the peak of the noise spectrum near 500Hz, smaller reductions are achieved. It is at this frequency and above that the rail noise dominates over the bridgestructure radiated noise. At and above the wheel is the dominant noise source and there is very little variation before and after the change was made to the track. Additionally, Fig. 4(a) shows the mean of measurements on the track atgrade. These were made at the slightly lower average speed of 60 km/hr. The noise from the wooden sleepers, which was identified by Twins modelling [7] to dominate below 800Hz, is in this case ‘baffled’ by the ballast and the ground reflection is expected to be fairly absorbing. This is in contrast to the open bridge structure and the reflectio n of the water surface. Additionally there is no control of the rail roughness accounted for in the parison. Despite these differences, it can be observed that the bridge noise has been lowered to levels similar to those of the atgrade track in the frequency bands up to 250Hz. The rail noise ponent is clearly much lower from the atgrade track than from the bridge (800Hz to ). 畢業(yè)設(shè)計(jì)外文文獻(xiàn)及譯文 9 Fig. 4. Comparison of predictions with measurements of average of freight trains。 , calculated from the slower freight trains , SF/ST project bined roughness for tread braked and (lower) for disc braked wheel。 plates in bending. It has been found sufficient to use a simplified version of SEA which assumes equipartition of energy. In this assumption the energy is dist