The reduction of structural vibrations on the example of two pedestrian bridges (in Poznań and Wrocław) with using of tuned mass dampers (TMD) has been presented in the paper. The results of theoretical and experimental studies of pedestrian bridge vibrations has been described and discussed. Basing on the results of calculations and measurements, tuned mass dampers (TMD) has been designed and mounted in the structure of the bridges. The measurements after the assembly of TMD show a high efficiency of vibration damping.
The paper shows the new method for noise reduction in external gear pumps based on the analysis of the pressure in inter teeth volumes. The simulation model and measurement results of pressure changes in the inter teeth volume has been presented. Based on simulation results an additional volume has been obtained, which is connected to the inter teeth volume (decompression filter volume). Due this additional volume the build down processes in the pump are longer and the pressure overdue in the inter teeth volumes are smaller. This leads to the reduction of the dynamical excitation forces inside the pump and noise, especially in the higher frequency rangeI.