Index of content:
Volume 111, Issue 4, April 2002
- TRANSDUCTION 
111(2002); http://dx.doi.org/10.1121/1.1456927View Description Hide Description
The underwater performance of a high-power multi-resonant Tonpilz transducer with a nearly flat frequency response and a power handling capability of 2 kW (peak) is reported here. A maximum transmitting voltage response (TVR) value of 156 dB re: 1 μPa/V at 1 m has been achieved at 3 kHz with a specially designed matching coil. A maximum receiving sensitivity (RS) of −164 dB re: 1 V/μPa at 3 kHz has been measured without using a matching coil. The horizontal half-power beam width of the transducer at 4 kHz is 101 degrees with a directivity index of 4 dB. This transmitter can be used for oceanographic applications such as subbottom profiling as well as long-range underwater communication.
111(2002); http://dx.doi.org/10.1121/1.1456926View Description Hide Description
This article addresses the way in which we can generate an “acoustically bright zone” in a space. The bright zone is defined as the volume where we can have higher acoustic energy than in other space. A method is proposed to generate the bright zone by controlling multiple monopole sources. Two kinds of cost functions involved with acoustic brightness are defined. One is the ratio of the brightness of a zone to the input power, and the other expresses the “contrast” between the bright zone and the other space. Through eigenvalue analysis, the optimal volume velocity distribution of the monopoles has been obtained.