I am a professor of acoustic imaging and signal processing at the University of Oslo and an elected member of the Norwegian Academy of Technological Sciences. Jointly with the Digital Signal Processing and Image Analysis group we are part of "Centre for Innovative Ultrasound Solutions (CIUS)" - a centre for research-based innovation.
My main interest is to understand the physics of wave propagation in complex media like biological tissue. Cosmologist and astrophysicist Martin Rees says:
We can expect huge advances on three frontiers: the very small, the very large, and the very complex
More specifically I want to understand why wave propagation in complex media in medical ultrasound and elastography often results in power law frequency characteristics (attenuation and dispersion), and to uncover the physical basis for non-integer (fractional) derivative descriptions of waves - if indeed there is one.
From time to time I am on the panel of the popular national radio show NRK P2, "Tower of Abel" answering questions on acoustics in a wide sense and sometimes commenting on the history/philosophy of science. I have blogged since 2010, mainly in Norwegian, and some in English.
Apart from that I probably have too many interests. That includes history and philosophy of science, loudspeakers/audio coding, and amateur radio.
“In my opinion it is well written and it is highly readable with technical details under control. I have highly appreciated the idea of integrating several ideas from physical acoustics with those from linear viscoelasticity." G. Saccomandi, Math Rev, Nov 2019
YouTube channel with lectures on the Physics of Fractional (Non-integer) Derivatives.
"The imagined conflict: On science and God", Oct. 2021, in Norwegian.
Blog: Den innbilte konflikten. Try the translation menu in the upper right-hand corner. It works surprisingly well!
Invited presentations at Acoust. Soc. America Conf, SIAM Am. Inst. Ultrasound in Med etc in recent years
Member of editorial board of Fractional Calculus and Applied Analysis and Progress in Fractional Differentiation and Applications
- Member of Scientific Committee of the Indoor Positioning and Indoor Navigation Conference 2012-2017. In 2012 and 2013 I also lead industry panel debates at the IPIN conferences
Presentations for download
- Lecture notes: From Diffraction to the Fourier Transform, 2021
- Differential arrays (IN5450) - from cardioid microphones to Yagi antennas (2020)
- Abel’s 1823 Paper on Fractional Derivatives, 27 Feb 2020
- Second harmonic imaging in active sonar (2016)
- Fractional derivatives (2016)
- Fascinating wave phenomena: Where Newton and Hooke fall short (2016)
- Processing the data twice: Minimum variance as an alternative to geometry-based beamforming (2016)
- Long delayed radio echoes – the illusive secret of the ionosphere (2021) first heard in Oslo in 1927.
- Youtube presentation at HamSci 2021.
- See also these pages which Wikipedia refers to:
- The Art of Writing a Scientific Paper (2015).
- See also blog with same title.
- Experience with sparse arrays (2007)
- Limited diffraction beams and a new decomposition of arbitrary annular beams (2002)
Demos and Software
- The best demonstration of a fractional derivative physical device is capacitor soakage or dielectric absorption: YouTube video.
- Some videos showing the fractional derivative of functions developed by former PhD student Vikash Pandey.
- Interactive program, Ultrasim, a Matlab toolbox for ultrasound field simulation.
- Magnitude squared coherence analysis software (Climate data).
The publication list from the database Cristin is not always so useful as it seems to be unable to distinguish between publications from several persons with the same name as me. Therefore it may be better to use my own list, Google Scholar, or ORCID.