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Obituary | Leif Bjørnø | 1937-2015
Leif Bjørnø, a Fellow of the Acoustical Society of America and a Life Fellow of the Institute of Electrical and Electronics En- gineers, was born on March 30, 1937, in Svendborg, Denmark, and passed away on October 24, 2015, following a distinguished career that combined academic research and industry. He was a Professor of Industrial Acoustics
in the Department of Industrial Acoustics at the Technical University of Denmark for 22 years and chairman of boards of directors for several companies, including Reson Akties- elskab.
In a career of over fifty years, Leif contributed over 400 pub- lications, covering many aspects of acoustics, invariably with practical applications. For example, his work on ultrasonics included industrial cleaning, suspended sediment transport, non-destructive evaluation of surface coating adhesion, and high intensity-focused fields. Some of his research had med- ical applications, notably the effect of acoustically induced shear stresses on gaseous microbubbles in biological tissue.
Some of Leif’s research encompassed naturally overlap- ping topics, notably wave propagation and scattering, and underwater acoustic modeling. The theoretical and model- ing approach was supported by experiments and, in some cases, system design and sea trials. On the propagation and scattering theme, examples of his work include studies of the acoustic non-linearity of inhomogeneous media, scatter- ing by water-loaded spherical metal shells (both filled and empty), and scattering by air bubbles near the sea surface. A loosely related theme was the generation of underwater noise due to rainfall.
On the modeling theme, Leif worked on the simulated per- formance of an acoustic modem operating with phase-mod- ulated signals propagating in a time-varying, shallow-water channel and on pressure fields created by the dynamic scat-
tering of high-frequency signals from a moving sea surface. Further modeling studies were on the nature of water-satu- rated marine sediments, ray tracing in shallow-water chan- nels, and the design of broadband tonpilz underwater acous- tic transducers based on multi-mode optimization.
The main connecting thread of Leif’s contributions across these topics was seabed sediment characterization. His work in later years, following the non-linear acoustics theme, fo- cused on the design and trials of a parametric sonar for char- acterizing subsea layers, with applications such as surveying for pipelines, searching for lost cargo, and detecting buried mines. This was carried out in collaboration with multi-na- tional partners in European Commission “framework” proj- ects.
For Leif’s full CV, see https://goo.gl/kGO6Qz. In many publi- cations he took his mother’s maiden name, calling himself Leif Bjørnø Jensen. He published many papers with his wife, Irina Bjørnø, to whom we offer our sincere condolences.
Articles by Leif Bjørnø
Bjerrum-Niese, C., and Jensen, L. B. (1994). Influence of statistical surface models on dynamic scattering of high-frequency signals from the ocean surface (A). Journal of the Acoustical Society of America 96, 3232.
Lewin, P. A., and Jensen, L. B. (1982). Acoustically induced shear stresses in the vicinity of microbubbles in tissue. Journal of the Acoustical Society of America 71, 728-734.
Pumphrey, H. C., Crum, L. A., and Jensen, L. B. (1989). Underwater sound produced by individual drop impacts and rainfall. Journal of the Acoustical Society of America 85, 1518-1526.
Überall, H., Ahyi, A. C., Raju, P. K., Bjørnø, I., and Jensen, L. B. (2002). Cir- cumferential-wave phase velocities for empty, fluid-immersed spheri- cal metal shells. Journal of the Acoustical Society of America 112, 2713- 2720.
Written by:
Bryan Woodward, Email: bryanwoodward1@gmail.com Emeritus Professor of Underwater Acoustics Loughborough University, Leicestershire, LE11 3TU UK
Spring 2016 | Acoustics Today | 57