摘要:

The phase distortion of a sonar pulse reflected at the interface of two fluid media is determined theoretically, and curves of the reflected pulse are presented for a number of phase shifts. The incident pulse is one cycle of a sine wave. There is no distortion for phase shifts of 0, π, and π/2, although in the latter case the pulse is inverted. For intermediate phase shifts, the pulse is distorted and shows both a “precursor” and “tail.”

ISSN:0001-4966    

DOI:10.1121/1.1918939

出版商:Acoustical Society of America    

年代:1964

数据来源: AIP

摘要:

Shots of 1000, 2000, and 3000 lb of TNT, detonated on the bottom of the 150‐f (fathom) Northeast Trough of the Gulf of Maine, were monitored at deep hydrophone locations on the continental slope off the United States of America, Bermuda, and the Antilles. Four types of arrivals were received from these shots: (1) ground arrivals, which were received at distances up to 250 miles from the shot; (2) direct arrivals that traveled along great circle, all‐water paths to receivers up to 1800 miles away; (3) indirect arrivals that traveled down the Northeast Trough and thence to the receivers; and (4) reflections from seamounts that lie off the mouth of the Northeast Trough.

ISSN:0001-4966    

DOI:10.1121/1.1918940

出版商:Acoustical Society of America    

年代:1964

数据来源: AIP

摘要:

An approximate wave equationux+(a/x) u − (β/c02)uut′ = 0, wheret′ =t − x/c0, is derived for progressive plane (a= 0), spherical (a= 1), and cylindrical(a = 12)waves of finite amplitude in a lossless fluid. In the case of spherical and cylindrical waves, it is required that the spatial coordinatexbe large. Solutions of the equation satisfying an arbitrary but given boundary condition are obtained. When the source excitation is sinusoidal, generalized Bessel‐Fubini solutions may be found. Another set of exact solutions is found that corresponds to a sawtooth wave. From these solutions, amplitude‐decay formulas are derived that agree with results obtained previously by Mendousse, Rudnick, Westervelt, and Naugol'nykli.

ISSN:0001-4966    

DOI:10.1121/1.1918941

出版商:Acoustical Society of America    

年代:1964

数据来源: AIP