Leo Kärkkäinen

Distinguished Scientist
Helsinki NRC

Background

I received my PhD. from the University of Helsinki, Department of Theoretical Physics in 1990. For the two following years I was in the University of Bielefeld as a postdoc (rainy), which were followed by two postdoctoral years in the University of Arizona (sunny). The last postdoctoral year was in Niels Bohr institute in Copenhagen, from which I moved to Nokia Research Center, Finland in 1996.

Work

Beginning the year 2011 I am working in Nokia Research Center Media Technologies Laboratory, in a technology exploration and foresight position.

Research Interests

For my PhD. and post doc years I was involved in studying the properties of Quark Gluon Plasma at extremely high temperatures. In special, I was involved in studying the properties of the suspected phase transition in which the high temperature quark gluon plasma, where quarks are free condense to a hardron gas, where quarks are confined to protons and neutrons. My interests where broadly in the fields of high temperature quantum field theory, phase transitions, critical points, Monte Carlo simulation , large scale parallel computing.

After Posdoc years my interests shifted to acoustics, a standard classical field theory, particularily the ways of predicting the acoustic performance of sound in small cavities, using Finite Element Methods (FEM). In particular, I wanted to understand the effects beyond Helmholtz equation - using Linearized, harmonic Navier-Stokes equations, we have found the methods that are accurate enough to predict the acoustic behaviour of mobile phones. If you want to hear the difference, just try the sound of Nokia 3250 or the 3D-sound of Nokia 6270, designed with the FEM design initiated in Nokia Research Center. I have also given some courses in acoustics in the Universisty of Helsinki Physics Department http://www.physics.helsinki.fi/courses/s/akustiikka/

But, to be honest, I am a person with quite wide interests, rather requiring a reason not to be interested in something than the other way a round.

Publications

On the sound fields of infinitely long strips Tim Mellow and Leo Kärkkäinen J. Acoust. Soc. Am. 130, 153 (2011)

Electron transport in edge-disordered graphene nanoribbons. Karri Saloriutta, Y. Hanckock, Asta Kärkkäinen, Leo Kärkkäinen, Martti J. Puska, Antti-Pekka Jauho Phys. Rev. B 83, 205125 (2011)

A dipole loudspeaker with a balanced directivity pattern Tim Mellow and Leo Kärkkäinen, J. Acoust. Soc. Am. 128, 2749 (2010)

Comparison of spheroidal and eigenfunction-expansion trial functions for a membrane in an infinite baffle. Tim Mellow and Leo Kärkkäinen, J. Acoust. Soc. Am. 123, 2598 (2008)

On the sound field of a shallow spherical shell in an infinite baffle. Tim Mellow and Leo Kärkkäinen J. Acoust. Soc. Am. 121, 3527 (2007)

Simulation of the transfer function for a head-and-torso model over the entire audible frequency range. Tomi Huttunen, Eira T, Seppälä, Ole Kirkeby, Asta kärkkäinen, Leo Kärkkäinen, Journal of Computational Acoustics 15, 429, (2007)

On the sound field of an oscillating disk in a finite open and closed circular baffle. Tim Mellow and Leo Kärkkäinen, J. Acoust. Soc. Am. 118, 1311 (2005)

The Equation of state for two flavor QCD at N(t) = 6. MILC Collaboration (Claude W. Bernard et al.). Phys.Rev.D55:6861-6869,1997.

The beta function and equation of state for QCD with two flavors of quarks. T. Blum, Leo Karkkainen, D. Toussaint (Arizona U.) , Steven A. Gottlieb (Indiana U.). Phys.Rev.D51:5153-5164,1995.

Interface tension in quenched QCD.Y. Iwasaki, K. Kanaya (Tsukuba U.) , Leo Karkkainen (Arizona U.) , K. Rummukainen (CERN) , T. Yoshie (Tsukuba U.) Phys.Rev.D49:3540-3545,1994.

Tension of the interface between two ordered phases in lattice SU(3) gauge theory. K. Kajantie (Helsinki U.) , Leo Karkkainen (Helsinki U. & Bielefeld U.) , K. Rummukainen (Helsinki U.) Nucl.Phys.B357:693-712,1991.

Interface Tension In Qcd Matter. K. Kajantie, Leo Karkkainen, K. Rummukainen (Helsinki U.) Nucl.Phys.B333:100,1990.