On the basis of the existing research results, after a systematic research of the wavelet neural network model, we found that the slow convergence and easily get into local optimal solutions. To solve this problem, using artificial firefly optimization method to optimize the parameters in wavelet neural network, and Artificial Firefly Wavelet neural network model is established. Apply this model to the Shandong coal demand forecast achieve better results, proved that establishing artificial Firefly Wavelet neural network model is scientific and feasible.

The bracket cracked and ground cable broken have occur to axle box many times on certain line metro vehicle. In view of this kind of accident, vibration test, vibration analysis, modal analysis as well as structure optimization are carried out for the axle box bracket of the subway. The test results show that the first transverse bending mode of the bracket is excited by the line vibration, so, it breaks due to vibration fatigue in the resonant state. The simulation results show that the modal frequency can be increased by thickening the bracket and optimizing its structure, so that avoiding resonance phenomenon and increasing its fatigue life. Finally, experiments are carried out to further verify the conclusion, and the structure that performs best can be chosen among multiple optimizations.

To predict the resonance characteristics of hydraulic machinery, it is necessary to accurately calculate the natural modes of the runners in the operating environment. However, in the existing research, the boundary conditions of the numerical modal analysis of the runner were not unified. In this paper, numerical modal analysis of a prototype Francis pump turbine runner was carried out using the acoustic–structure coupling method. The results of three different constraints were compared. The influence of the energy loss on the chamber wall on the natural modes of the runner was studied by the absorption boundary. The results show that the constraint condition (especially the rotating shaft) has significant impacts on the torsional mode, the radial mode, the 1 nodal-diameter mode, and the 0 nodal-circle mode, and the maximum differences in the natural frequencies under different conditions are 69.3%, 56.4%, 35.1%, and 9.4%, respectively. The change of the natural frequencies is closely related to the modal shapes. On the other hand, the energy loss on the wall mainly affects the nodal-circle modes, and the influence on other modes is negligible. The results can provide references for the design and resonance characteristics analysis of hydraulic machinery runners.

According to the chatter phenomenon of 3rd stand of a steelworks six-roller tandem cold mill (TCM), vertical vibration of tandem cold mill was simplified to eight degrees of asymmetric freedom mass-spring system. Virtual prototype model on vertical vibration of tandem cold mill was established and natural frequencies and main vibration mode of mill were solved by using automatic dynamic analysis of mechanical systems in software ADAMS. The modal coordinates of main vibration mode of the mill were referred firstly and obtained; the maximal mode of vibration system was found and finally discovered the fifth-octave-mode chatter was the probable vibration of the mill.

The quality of high speed machining is directly related to dynamic characteristics of spindle-toolholder interface. The paper established normal and tangential interactions of BT spindle-toolholder interface based on finite element contact theory, and analysed free modal in Abaqus/Standard. Then the result was compared with the experimental modal analysis. It shows that the finite element model is effective and could be applied in the future dynamic study of high-speed spindle system.