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May 2011 Issue

REMUS 6000s Aid In Discovery of Air France Flight 447 Wreck
Hydroid Inc. (Pocasset, Massachusetts) announced in April that three of its REMUS 6000 autonomous underwater vehicles (AUVs) aided in discovering the wreckage from downed Air France Flight 447 nearly 2.5 miles below the surface of the Atlantic Ocean off the coast of Brazil.

It was the fourth search for the downed plane. The Airbus A330-200, traveling from Rio de Janeiro to Paris, crashed in June 2009 after encountering severe thunderstorms.

The search team, led by the Woods Hole Oceanographic Institution (Falmouth, Massachusetts), employed two REMUS 6000 vehicles owned by the Waitt Institute for Discovery and another owned by the Leibniz Institute of Marine Sciences.

On April 3, one week into the search, using the Hydroid REMUS 6000 vehicles equipped with EdgeTech (West Wareham, Massachusetts) dual-frequency side scan sonar and four-megapixel cameras, searchers discovered large pieces of debris, including parts of the aircraft's wings, engine, landing gear and fuselage. For more information, visit www.hydroidinc.com.

Resolve Marine Group Refloats Sunken Drydock in Shipyard
Resolve Marine Group Inc. (Fort Lauderdale, Florida) successfully raised and refloated the "machinist" drydock in March at Guam Shipyard in Apra Harbor, Guam, the company recently announced.

The 825-foot drydock sank in January during rough weather. Resolve, the successful bidder for the job, said it began the salvage January 31 and successfully refloated the drydock on March 3.

Company divers and engineers first conducted a comprehensive casualty assessment to determine the structural and watertight conditions of the drydock and to ascertain the status of drydock systems, Resolve said. A detailed engineering analysis was carried out and a salvage plan was developed and implemented, involving preparatory work both topside and underwater. Given the deep submergence of the drydock well beyond normal operating limits, the company said it worked to minimize hydrostatic pressures on tank boundaries during the refloating and to keep global hull stresses and stability within allowable limits. The U.S. Coast Guard and U.S. Navy reviewed and approved the salvage plan.

Due to the extensive maintenance being performed on the drydock prior to sinking, a large portion of its pumping system was inoperable. To overcome this, Resolve mobilized 12 high-capacity electric salvage pumps. Additionally, numerous gauging systems were established to monitor tank pressures and conditions throughout the refloat operation. For more information, visit www.resolvemarine.com.

CDL, Schilling Robotics Develop New MWSK Solution for ROVs
At the request of C-Innovation (Galliano, Louisiana), CDL (Aberdeen, Scotland) and Schilling Robotics LLC (Davis, California) engineers started work one year ago to develop an affordable and functional solution for mid-water station keeping (MWSK) by remotely operated vehicles (ROVs).

The results of that effort were demonstrated in March in the waters of the Gulf of Mexico following factory acceptance tests. The solution centers around fusing an inertial navigation system (INS), ultrashort baseline (USBL) positioning and a Doppler velocity log (DVL), and integrating those technologies with Schilling's closed-loop control system.

The companies said the heart of the solution is the CDL MiniPOS3 INS platform, which uses USBL position (and DVL when available) to produce a highly stable INS-aided solution feeding precise position, acceleration and rotation information directly to the control system on the ROV at update rates of up to 50 hertz.

During the trials carried out in March on the ultraheavy-duty ROV Chouest Holiday, C-Innovation performed an extensive set of test procedures to demonstrate the technology. The hardware-independent system can work with any USBL or long baseline system and a variety of topside software packages, the companies said. The first software package to fully support the MWSK functionality is WinFrog by Fugro Pelagos Inc. (San Diego, California), which was used during testing.

The absolute positioning accuracy of the ROV (without DVL) was noted at a standard deviation of less than 40 centimeters during MWSK, the companies said, and with a DVL lock it improved to approximately three centimeters. For more information, visit www.cdltd.net.

Divex Unscrambles Diver Voices for 'Mighty Ships' TV Episode
Divex (Aberdeen, Scotland) recently provided assistance to the Discovery Channel for a "Mighty Ships" episode, using its HeliCom technology to unscramble raw helium audio.

The "Mighty Ships" series follows various types of vessels on a journey, depicting how the ship and its crew operate.

While filming onboard the Skandi Arctic for a forthcoming episode, the Discovery Channel made a number of raw helium audio recordings of diver speech, including those of divers in saturation chambers and while diving at depth. Divex said it unscrambled the raw helium audio files at their headquarters, providing the Discovery Channel with clear audio files that can be used in the documentary.

"We tried to modulate the pitch of the diver's heliox-induced voices in our sound studio with no success," said John LaRose, a producer with the television series. "When the audio files came back from Divex after being run through their HeliCom unscrambler, all we could say was, 'How did they do that'"

The technology achieves diver helium voice communication through digital signal processing techniques. The helium speech from the pressurized divers and the chamber occupants are mixed in an audio mixer before decoding to the selected gas and environmental settings by a digital signal processing circuit, Divex said.

The technology incorporates precise modeling of the translations introduced by the heliox mixture on the human voice including both pitch and envelope distortion, Divex said.

For more information, visit www.divexglobal.com.

2012:  JAN | FEB | MARCH | APRIL | MAY | JUNE | JULY | AUG | SEPT | OCT | NOV | DEC
2011:  JAN | FEB | MARCH | APRIL | MAY | JUNE | JULY | AUG | SEPT | OCT | NOV | DEC


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