Honeycomb phononic crystal can obtain wider band gaps in the low frequency based on local resonance theory. Its band structure can be adjustable if we change the height of the cores, which means different kinds of honeycomb phononic crystal can be selected on the basis of different damping demands. Meanwhile, the point defects and line defects affect the localized modes of sound waves and propagation characteristics, the dispersion relations and the displacement fields of the eigenmodes are calculated in the defected systems, as well as the propagation behaviors in the frequency ranges of the band structure, which are also discussed in detail. We constructed the model based on the periodic boundary condition and calculated the band structure according to Bloch theory, and also performed a series of simulation through the COMSOL software, showing that honeycomb has excellent features in reducing noise and vibration, which has a far-reaching influence in designing the new type of acoustic wave devices.

There has been a number of initiatives launched in the field of lubrication as potentialsources of improvements in energy efficiency in a wide range of engineering products,plant and processes. Attention is being focussed on bearings to improve both performanceand efficiency in fields such as automotive, machine tools, industrial and powergeneration plant. This paper reviews some of the background to these drives andillustrates how a novel design of adjustable fluid film hydrodynamic journal type bearingshows promise to both improve performance and save energy. Theoretical modelling andpractical tests have demonstrated clear improvements over conventional fluid filmbearings, along with a number of other characteristics offering benefits that may be ofinterest to designers and users of such bearings.