Renhe Zhang Yi He Baixian Zhu Dinghua Guan
State Key Lab. of Acoust., Chinese Acad. of Sci., Beijing 100080, People's Republic of China
The ambient noise in shallow water is more complicated than that in the deep sea, and it has greater geographical and seasonal variations since there is a strong bottom interaction. A theoretical model of ambient sea noise including surface-noise sources and a stratified medium ocean is discussed. The noise sources are assumed to be statistically independent directional point sources distributed over the sea surface. The effects of the surface--source feature, velocity profile, and bottom property on ambient noise are studied. In general, the ray theory is suitable for calculating the contribution of near-field sources, whereas the normal-mode theory is appropriate for far-field sources. In this paper, a ray-mode theory suitable for near- and far-field sources is developed. The concise formulas for calculating the intensities, spatial correlation, and vertical directivity of ambient noise are present and some numerical simulations are given. Standards Committee S2 on Mechanical Vibration and Shock. Working group chairs will present reports of their recent progress on writing and processing various shock and vibration standards. There will be a report on the interface of S2 activities with those of ISO/TC 108 (the Technical Advisory Group for ISO/TC 108 consists of members of S2, S3, and other persons not necessarily members of those committees) including a report on the current activities of ISO/TC 108, and plans for the next meeting. SCOPE OF S2: Standards, specifications, methods of measurement and test, and terminology in the fields of mechanical vibration and shock, and condition monitoring and diagnostics of machines, but excluding those aspects which pertain to biological safety, tolerance, and comfort.