Beam Reach

Thanks to Lindsay Delp (081) who just sent me a Discovery Channel article about the fluid mechanical efficiency of cetacean fins and flukes. It turns out (ha!) that wind turbines can be made more efficient by roughening the leading edge of the blades. The idea was inspired by studying the bumpy fins of humpback whales.

Seems like a nice next step (alluded to in the article) would be for the Beam Reach boats to substitute robotic flukes for the propellers! I’ll bet the resultant propulsion would be not only more efficient, but also more quiet underwater. Perhaps some day the whole whale watching fleet will be using different flukes, optimized for making Zodiacs porpoise and deep-keeled boats thrust silently along at 5 knots?

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Beam Reach has made quite a contribution at the Paris 2008 Acoustics Conference.  Jason’s report on his elephant footfalls was well received on Monday with his work on new census techniques fitting in well with the many talks on marine acoustics survey techniques.  My talk on documenting ‘communication’ between a calf and its mom/brother elicited some good questions and much conversation on just what is conversation anyway afterwards in the halls and at lunch.  And Kenna brought Zipf’s slope to the attention of the marine mammal community and she did an excellent job of both presenting and answering the large number of questions that her talk elicited.  People came up to me afterwards and said “is she really an undergraduate?

I have talked about Beam Reach with many acousticians here and the 100 or so people in attendance of the marine mammal sessions certainly have seen Beam Reach returning research results to the community.  I know that this will enhance the program and I hope that the word about what Beam Reach can accomplish spreads to draw in excited and qualified applicants in tthe future.

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I’ve been spending a large part of my time doing analysis trying to localize calls in Ishmael. Since I never had a situation where the entire group was social. I have to localize the calls from each social period to see if they came from the social group or not. The way you do that is by opening the file in a program called Ishmael, imputing your hydrophone data, selecting a call, and pressing localize. When you do that Ishmael looks at the four channels that were recorded and calculates the difference in time it took for the sound to reach the four hydrophones. It can then use this to calculate the location of the call.

Unfortunately Ishmael is not perfect and neither are our recording conditions. Since the ocean is a noisy environment with lots of background noise there are times that it can’t distinguish above the background noise and will give you some strange answer that sometimes invloves the animal being millions of miles away. Also, if a call is made directly in front or behind the array it can’t localize well because the sound waves are coming straight on. Because of this I have a lot calls which can’t be localized well if at all.

All in all this is doing nothing to make the frantic last week of analysis and paper writing easier. That said, it is slowly bit by bit getting done and I feel good that I will be able to pull everything together and be able to have a good presentation ready come Saturday morning.

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