Papers by Keyword: Transverse Wave

Abstract: In the given work, on the basis of the carried out researches at the decision of seismic surveying tasks an attempt on advancement of methods and means of excitation of elastic vibrations by the generator of seismic vibrations (GSV) is made. The geometry of the real GSV differs from the ideal axially symmetric form resulting in deviations of parameters of geometry of mass (deviations of the centre of mass, main central axes of inertia), and is a consequence of the static and dynamic disbalance.The character of forces and moments acting on the GSV, as a whole and on separate units, depends on quality of the law of change of total force of resistance of escapement and return of plunger; dynamic loads resuling in occurrence of transverse waves at excitation of seismic vibrations deterioting the accuracy of determination of well bottom position are formed.

Abstract: In order to elucidate the different characters of elastic waves caused respectively by screw and edge dislocation movement, we calculated the stain field disturbance caused by migration of dislocation by elastic theory. Through the calculation, it was found that the strain field disturbance resulted from screw dislocation migration produces a transverse wave radiation while that resulted from edge dislocation migration produces transverse wave and longitudinal wave simultaneously. The result reveals the different energy radiation characters of screw dislocations and edge dislocations and explains the reason that edge dislocation moves faster than screw dislocation in general experiment. It also provides a theoretical basis for determining microcosmic mechanism of plastic deformation of metals by monitoring the changes of elastic waves.

Abstract: Longitudinal ultrasonic wave signals, transverse ultrasonic wave signals and other ultrasonic body wave signals generated by partial discharge are analyzed emphatically in the acoustic emission method of partial discharge detection in high voltage equipment [1-. Velocity of longitudinal ultrasonic wave is often used to calculate partial discharge defects position in the location study of partial discharge. In practical applications errors are always large. And a recent study finds that a class of plate ultrasonic guided waves will be inspired when ultrasonic body waves are transmitted from the gaseous medium to the metal medium [9-1. As the attenuation coefficient is small and the transmission distance is large when the waves propagate along the metal plate, in the partial discharge detection, ultrasonic signals detected by the ultrasonic sensor attached to the equipment enclosure include ultrasonic guided waves besides the ultrasonic body waves.

Abstract: Basing on the theory of power flow, frequency response analysis was acted on in a hydropower house under dominant frequency with measured data of Three Gorges Station in spiral case and draft tube. Power flow in walls was calculated by APDL procedure and the properties were analyzed. The conclusion is that longitudinal wave is the main method in walls of the powerhouse, energy is reflected and stacked at the top of the walls. Displacement along the river changes and power flow in walls decays obviously. Intensity of vibration origin and distance between the vibration and the wall are both the influencing factors，increasing the stiffness of buttressed walls takes the role of limiting flexural wave and shear wave effect

Abstract: In this paper, a method based on the displacement-traction map is developed to calculate the bandgaps of transverse waves propagating in a 2D phononic crystal composed of nanosized circular holes in a square lattice. The Young-Laplace equation is employed to take into account of the surface effects of the nanosized holes. Detailed calculations are performed for the system with nanosized circular holes in an aluminum host with or without the surface effect. The result shows that all bands descend with the first bandgap becoming wider due to the existence of the surface effects.