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Mathematical Sciences
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William Siegmann
Department of Mathematical Sciences Faculty:

Kristin Bennett
Mohamed Boudjelkha
Margaret Cheney
Donald Drew
Joseph Ecker
Joseph E. Flaherty
Isom Herron
Mark Holmes
David Isaacson
Ashwani Kapila
Maya Kiehl
Gregor Kovacic
Peter Kramer
Fengyan Li
Chjan Lim
Yuri Lvov
Harry McLaughlin
Joyce McLaughlin
John Mitchell
Clifford Nolan
Bruce Piper
Victor Roytburd
Lester Rubenfeld
David Schmidt
Donald Schwendeman
William Siegmann
Michael Zuker

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Mathematical Sciences Faculty
William Siegmann

Associate Dean of Science for Graduate Education and Research; Professor of Mathematical Sciences; Member, Faculty of Information Technology

Education:

Ph.D., Massachusetts Institute of Technology

Research Areas:

Advances in asymptotic methods, computing power, and numerical algorithms have invigorated research in the analysis of wave propagation. Professor Bill Siegmann and a group of doctoral and masters' students work actively together on variety of propagation problems. The principal applications involve acoustic transmission in the ocean, and others have been directed toward both electromagnetic and acoustic waves in the atmosphere.

New parabolic wave equations and new solution methods are under development, in order to account for dominant variations of the propagation medium. These methods, like their predecessors constructed in recent decades, are based on accurate asymptotic approximations to scalar and vector wave equations. The continued success and appeal of parabolic approximations result from the very efficient computational marching algorithms that are available for their solution. Applications of our new results include sound transmission through shallow-water regions (especially with substantial changes in the propagation direction, including interactions with beaches and islands), improved procedures for ocean acoustic tomography (in which ocean properties are estimated using acoustic signals), and sound propagation that penetrates the ocean bottom (incorporating effects of the elasticity or pro-elasticity of sediment layers). Increasing the computational efficiencies of high-order parabolic approximations is also under investigation.

Other problems concern the prediction of the propagation of pulse signals in complex ocean channels. New methods are being constructed for describing the nonlinear effects of relatively strong pulse sources. Computationally accurate and efficient approximations of parabolic type are providing new capabilities for solutions of these problems. Representing random ocean variablities in novel and efficient ways for estimation of propagation statistics is also under active study.

Selected Publications:

“Beach Acoustics,” J. Acoust. Soc. Am. 97, 2767-2770, 1995 (with M.D. Collins and R.A. Coury).

“Jovian Acoustics and Comet Shoemaker - Levy 9,” J. Acoust. Soc. Am, 97, 2147-2158, 1995 (with M.D. Collins, B.E. McDonald, and W. A. Kuperman).

“Convergence Zone Feature Dependence on Ocean Temperature Structure,” J. Acoust. Soc. Am. 100, 3033-3041, 1996 (with K.P. Bongiovanni and D.S. Ko).

“Effects of a Sediment Scattering Layer in Underwater-Acoustics Studies of Intensity Sensitivity and Data Modeling,” J. Acoust. Soc. Am. 100, 1971-1980, 1996 (with K.J. Howell, M.J. Jacobson, and W.M. Carey).

“Wave Propagation in Poro-Acoustic Media,” Wave Motion, 25, 265-270, 1997 (with M.D. Collins and J.F. Lingevitch).

“Nonlinear Wide-Angle Paraxial Acoustic Propagation in Shallow-Water Channels,” J. Acoust. Soc. Am. 102, 224-232, 1997 (with R.S. Kulkarni and M.D. Collins).

Contact Information:

William Siegmann
(518) 276-6905
siegmw@rpi.edu

More Info:

http://eaton.math.rpi.edu/faculty/Siegmann/bsieg.html

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