I am a professor of signal processing and acoustical imaging at the University of Oslo and a member of the Norwegian Academy of Technological Sciences. Our group is part of "Centre for Innovative Ultrasound Solutions (CIUS)" - a centre for research-based innovation.
My main research interest is to understand complexity, more specifically to understand wave propagation in complex media like human tissue for medical ultrasound and elastography. A special focus is on understanding why this often results in power law characteristics (attenuation and dispersion), and to uncover the physical basis for non-integer (fractional) derivative descriptions of waves in these media. Combination of linear viscoelasticity and acoustic/elastic wave theories seems to be particularly useful.
Apart from that I probably have too many interestes. In addition to compressional and shear waves propagation, that includes indoor positioning with ultrasound, history and philosophy of science, data analysis for climate, audio/HiFi/audio coding, and ham radio.
Invited presentation "Thermodynamically viable wave equations for power law attenuation in viscoelastic media," in session on "Impact of soft tissue inhomogeneities and bone/air on ultrasound propagation in the body,” Acoustics '17, Boston, June 2017
Invited minisymposium presentation, “Thermodynamically viable fractional wave equations for power law attenuation in viscoelastic media,” in session on “Data-Driven Fractional Modeling, Simulation and Prediction,” SIAM Conference on Computational Science, Atlanta, GA, 27 Feb-3 March 2017
Invited presentation, Am. Inst. Ultrasound in Med., "Processing the data twice: Minimum variance as an alternative to geometry-based beamforming", New York, NY, 17-21 March 2016.
Invited keynote, IEEE/OES China Ocean Acoustic Symposium, "Wave propagation in marine sediments expressed by fractional wave and diffusion equations," 9.-11. Jan 2016, Harbin, China.
Member of editorial board of "Progress in Fractional Differentiation and Applications", 2015
- Member of the Scientific Committee of the Indoor Positioning and Indoor Navigation Conference 2012-. In 2012 and 2013 I also lead industry panel debates at the IPIN conferences.
The image above, with Peter Näsholm, is from the article "New cancer detection method right around the corner", February 2013 - also on Science Daily (c).
Demos and Software from the DSB Group
- Acoustic radiation force visualization. Notice how the force can both push as well as pull. (YouTube video by Fabrice Prieur)
- Here are some videos showing the fractional derivative of functions like the exponential function, the power function, and the sine function. They were developed by Vikash Pandey.
- The best demonstration of a fractional derivative physical device is capacitor soakage or dielectric absorption. Here's a YouTube video I made showing this effect.
- Real-time GPU simulator for ultrasound fields, "Huygens on Speed" (YouTube video by Jon Petter Åsen)
- Theremin controlled by ultrasound rangefinder (YouTube video by Eirik Renton)
- Ultrasound-based thermometer (YouTube video by Martin A. Brinkmann)
- Touch sensitive blackboard (YouTube video)
- Try our applet for optimization of a sparse array's layout. Can you make it to the hi-score list?
- You may download our interactive program, Ultrasim, a Matlab toolbox for ultrasound field simulation.
- Climate data analysis software.
Videos from spin-off and collaborating companies
- Elliptic Labs: Ultrasound proximity technology in Xiaomi phones, Touchless Gesture
- Squarehead Technology:
- Sonitor Technologies: Real Time Location Systems