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Dive into the research topics where Richard Zimmerman is active.

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Featured researches published by Richard Zimmerman.


Journal of the Acoustical Society of America | 2005

Underwater acoustic measurements with the Liberdade/X‐Ray flying wing glider

Gerald L. D’Spain; Scott A. Jenkins; Richard Zimmerman; James C. Luby; Aaron Thode

An underwater glider based on a flying wing design (Jenkins et al., 2003) presently is under development by the Marine Physical Laboratory, Scripps Institution of Oceanography and the Applied Physics Laboratory, University of Washington. This design maximizes the horizontal distance between changes in buoyancy to minimize mechanical power consumed in horizontal transport. The prototype wing has a 6.1 m wing span and is 20 times larger by volume than existing gliders. Initial at‐sea tests indicate that the lift‐to‐drag ratio is 17/1 at a horizontal speed of about 1.8 m/s for a 38‐liter buoyancy engine. Beamforming results using recordings of the radiated noise from the deployment ship by two hydrophones mounted on the wing verify aspects of the prototype wing flight characteristics. The payload on the new glider will include a low‐power, 32‐element hydrophone array placed along the leading edge of the wing for large physical aperture at midfrequencies (above 1 kHz) and a 4‐component vector sensor. Data pre...


Journal of the Acoustical Society of America | 2007

Underwater acoustic measurements with a flying wing glider

Gerald L. D’Spain; Richard Zimmerman; Scott A. Jenkins; James C. Luby; Peter Brodsky

Liberdade, a new class of underwater glider based on a flying wing design, has been under development for the past 3 years in a joint project between the Marine Physical Laboratory, Scripps Institution of Oceanography and the Applied Physics Laboratory, University of Washington. This hydrodynamically efficient design maximizes the horizontal distance traveled between changes in buoyancy, thereby minimizing average power consumed in horizontal transport to achieve ‘‘persistence.’’ The first fully autonomous glider of this class, ‘‘XRay,’’ was deployed and operated successfully in the Monterey Bay 2006 experiment. Communications, including real‐time glider status reports, were accomplished using an underwater acoustic modem as well as with an Iridium satellite system while on the surface. The payload included hydrophone array, with 10 kHz per channel bandwidth, located in a sonar dome along the leading edge of the 6.1‐m‐span wing. Narrowband tones from 3.0 to 8.5 kHz were transmitted from a ship‐deployed controlled underwater source. During the glider’s flight, lift‐to‐drag ratios (equal to the inverse of the glide slope) exceeded 10/1. However, specific flight behaviors that deviated from this efficient horizontal transport mode allowed for improved detection and localization by the hydrophone array. [Work sponsored by the Office of Naval Research.]


Journal of the Acoustical Society of America | 1997

The MPL sound velocimeter: An instrument for in situ sound velocity measurements in the deep ocean

Aaron D. Sweeney; Fred N. Spiess; Dwight E. Boegeman; David M. Jabson; Richard Zimmerman

A sound velocimeter designed to measure sound speed to a precision of 1 part in 105 has recently been tested at sea. The device was used in conjunction with a CTD to check agreement with sound speeds computed from popular empirical equations [C.‐T. Chen and F. J. Millero, J. Acoust. Soc. Am. 62, 1129–1135 (1977); V. A. DelGrosso, J. Acoust. Soc. Am. 56, 1084–1091 (1974)]. Disagreements will be discussed. High‐precision travel‐time measurement is achieved through use of a phase‐comparison technique. For this purpose, the device determines the number of cycles of the acoustic signal between the transmitted pulse and received echo, adjusting the frequency until the echo and transmitted pulse are in phase. The travel time is the product of the signal period and the number of cycles between the outgoing and incoming pulses. The velocimeter’s capability of measuring travel time at several different frequencies near 4 MHz serves as a check on the timing consistency, since the travel time should be independent of...


Journal of the Acoustical Society of America | 2014

Decreasing the radiated acoustic and vibration noise of both prop-driven and buoyancy-driven autonomous underwater vehicles

Richard Zimmerman; Gerald L. D'Spain; Peter Brodsky; Mark Stevenson; Mark A. Zumberge; John A. Orcutt

Our previously published results from decreasing the radiated acoustic and vibration noise of a mid-size, prop-driven autonomous underwater vehicle (AUV) show self noise levels recorded at sea by an AUV-mounted hydrophone array that are at, or below, typical background ocean noise levels across the frequency band above 200 Hz. The remaining noise below 200 Hz is primarily vibration induced. The modifications required to achieve this 20–50 dB reduction in propulsion and steering system noise levels will be reviewed in this talk. In addition, at-sea measurements of the acoustic noise radiated by the large (30 L) buoyancy engine on a 20-ft wing span flying wing autonomous underwater glider are presented. Whereas a prop-driven system operates continuously, the buoyancy-driven propulsion system has a very low duty cycle of a few percent; it is on only for about 3 min during each dive cycle. Onboard self noise from the gliders internal fluid-based roll control system far exceeds that from an aileron-based syst...


Journal of the Acoustical Society of America | 2010

Decreasing the radiated acoustic and vibration noise of a mid‐size, prop‐driven, autonomous underwater vehicle.

Richard Zimmerman; Gerald L. D’Spain; John A. Orcutt

Previously published efforts at decreasing the radiated acoustic and vibration noise of the propulsion system of an Odyssey IIb autonomous underwater vehicle (AUV) manufactured by Bluefin Robotics, Inc. resulted in noise levels recorded by an AUV‐mounted hydrophone array that were at or below typical background ocean noise levels across much of the frequency band from 300 Hz to 10 kHz [IEEE J. Ocean. Eng. 30, 179–187]. The modifications required to achieve this 20–50‐dB reduction in propulsion noise levels will be reviewed in this talk. Recently, these modifications have been incorporated into the Bluefin 21 AUV at the Scripps Institution of Oceanography. In addition, the stepper motors in the linear actuators used to steer this AUV’s vectored‐thrust tail cone in depth and heading have been replaced. At‐sea measurements show that the high‐level, broadband transients that previously occurred every 2–3 s due to these actuators are no longer visible in the hydrophone data. Eliminating these sources of self‐n...


Journal of the Acoustical Society of America | 2007

High‐resolution repeat bathymetric mapping using a mid‐size autonomous underwater vehicle

Gerald L. D’Spain; Richard Zimmerman; C. David Chadwell; Mark A. Zumberge; John Blum; John A. Orcutt; Neal W. Driscoll; Jeff Dingler; Graham M. Kent; Hugh H. Banon; Graham Openshaw; Philippe Jeanjean

Shipborne bathymetric surveys south of Santa Barbara, CA indicate that massive slope failures have occurred along the northern flank of the Santa Barbara Basin. This region is seismically active and has the highest sedimentation rates along the California coast due to rapid erosion of the Transverse Ranges. A set of geodetic monitoring systems is being developed to study the character and deformation of the ocean bottom in this region, particularly that of a prominent east‐west trending crack aligned with the head scarp of one of the underwater landslides. One component is a high‐resolution repeat bathymetric mapping system composed of a multibeam sonar mounted inside a Bluefin 21 AUV. Navigation to the decimeter level is provided by an inertial navigation system and accurate depth sensor, and by a long baseline (LBL) acoustic transponder system previously developed to monitor tectonic plate motions. The quality of the data, particularly that from the high‐precision LBL system, is enhanced significantly b...


Journal of the Acoustical Society of America | 2004

Passive acoustic localization with an AUV‐mounted hydrophone array

Gerald L. D’Spain; Eric Terrill; C. David Chadwell; Jerome A. Smith; Richard Zimmerman

A mid‐size Odyssey IIb autonomous underwater vehicle (AUV) was retrofitted with the advanced vectored‐thrust system presently installed on AUVs manufactured by Bluefin Robotics, Inc. Subsequent modifications to this thrust system decreased the radiated acoustic and vibration noise levels recorded by an eight‐element hydrophone array mounted on the AUV’s inner shroud by 20 to 50 dB across the 20 Hz to 10 kHz band. This reduction in self‐noise levels to near, or at, background ocean noise levels permits the use of the vehicle‐mounted hydrophone array in passive ocean acoustic studies. One example is the application of passive synthetic aperture processing techniques to provide greater spatial resolution estimates of the direction of low frequency sources. Doppler spreading caused by medium motion is a limiting factor in array gain. At mid frequencies (1–10 kHz), the complexity of the received acoustic field created by scattering off the AUV body is partly captured in the array processing by the use of repli...


Journal of the Acoustical Society of America | 2002

An AUV underwater acoustic array

Gerald L. D’Spain; Paul A. Lepper; Richard Zimmerman

An eight‐element hydrophone array has been installed within the shroud of an Odyssey IIb AUV. Each array channel is digitized and recorded with 10‐kHz bandwidth by an autonomous, PC‐104+ data acquisition system. To determine the effects of the AUV body itself on the acoustic field measured by the array, tones at low (200–800 Hz) and mid‐ (2–8 kHz) frequencies were transmitted in a large water tank to the AUV by a source continuously varying in azimuth but fixed range. Bartlett beamforming for source azimuth using both plane wave replicas and replicas calculated using a 2‐D time domain, finite‐difference code that accounts for the scattering from the two glass spheres in the AUV shows that (1) not accounting for scattering results in 2‐ to 6‐dB signal gain degradation, but (2) scattering moves the ambiguity surface sidelobes closer to the main lobe location, thus improving localization capability. The effect of scattering from the AUV on an azimuthally isotropic noise field, estimated by averaging over pin...


Archive | 1998

Broadband borehole seismic system integration tests : report of the system integration tests at MPL/SIO

Robert G. Goldsborough; Gary Austin; S. Thompson Bolmer; David M. Jabson; Patrick Jonke; Matthew R. Gould; John A. Hildebrand; C. B. Hollinshead; G. Offield; John A. Orcutt; Kenneth R. Peal; Fred N. Spiess; Ralph A. Stephen; Frank L. Vernon; David F. Willoughby; Richard Zimmerman

This work is sponsored by the National Science Foundation Grant Nos. OCE 9522114and OCE 9523541 with additional support from Scripps Institute of Oceanography and Woods Hole Oceanographic Institution


Archive | 2009

Autonomous Underwater Vehicle Borne Gravity Meter

Mark A. Zumberge; Glenn S. Sasagawa; Richard Zimmerman; Jeff Ridgway

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John A. Orcutt

University of California

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Fred N. Spiess

Scripps Institution of Oceanography

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James C. Luby

University of Washington

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