The low-frequency vibration of the bucket wheel excavator has an important impact on the fatigue life of the structures. For conventional vibration testing methods, it is difficult and expensive to excite the overall low-frequency vibration of the whole machine. Hence, in this paper, the excitation method that uses the belt-supporting rollers on the boom as an exciter is tried to excite the low-frequency vibration, so that the low natural frequencies can be identified by Fourier transforming the free decay signals caused by the sudden power off. By this method, the first five natural frequencies are obtained, and the results are verified through corresponding computational numerical model of the bucket wheel excavator. It can be concluded that the proposed testing method can achieve the same accuracy but is much more convenient and costs less than existing methods.

The circular polarization of Lyman-a photons resulting from beam-tilted-foil excited H(2p) was measured at energies between 9 and 20 keV with foil tilt angles up to 60". Various interaction models are used to fit the data, and their physical significance is discussed.