Spin-1 and spin-2 fields

Massive and massless spin-1 and spin-2 fields, their field equations and propagators are studied. The connection between local gauge symmetry and the coupling to a conserved current is derived in the massless case. The dynamical stress tensor is defined as source of gravity, and its local conservation is shown. The basic ideas of large extra dimensions is outlined in an appendix.

Research on Vibration Responses of Railway Steel Bridge Considering Welding Residual Stress

Vibration responses of railway steel bridge considering welding residual stress have been researched. Based on the reasonable heat source model matching the electrical arc welding, the welding residual stress in welding joints of steel bridge has been simulated. Meanwhile, it has been superimposing with the gravity stress and the actual measured dynamical stress of railway steel bridge. Then, acting all actions to the accurate finite element model, the vibration responses of railway steel bridge considering welding residual stress can be analyzed, and the conclusion that the residual stress has a significant contribution to the vibration dynamical stress in welding joints district of railway steel bridge has been obtained.

Theoretical Analysis and Experimental Study on Acoustic Emission Wave Propagation in Perforated Thin-Walled Plate

Through complex variables function, wave propagation of perforated thin-walled plates is deduced. And it is found out that the dynamical stress concentrates where the concentration parameter vertical to incident orientation is about 1.5, and with the increase of incident wave frequency, holes have less influence on the dynamical stress concentration during wave propagation. With the help of acoustic emission technique, holes do not have much effect on nondestructive test of acoustic emission.