
Ryuji Tokunaga
Professor, Department of computer science, University of Tsukuba
[Biography  Research Interests  Papers  Proceedings  Books]
Biography
Ryuji Tokunaga received the B.E., M. and Dr.eng. degree all in electrical engineering from Waseda University. He was with the Department of Elecrtical Engineering and Computer Sciences, University of California, Berkeley as a Visiting Scholar. And He was an Assistant Researcher at Waseda University. Presently, he is an Assistant Professor at the Department of Computer Sciences, University of Tsukuba.
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Research Interests
Chaos, fractals and bifurcation theory. Computer amusement oriented elementary technologies.
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Papers (in English only)
 M.Kawamura, R.Tokunaga and M.Okada,
"Bifurcation analysis in an associative memory model",
Physical Review E 70, no.41, 046210, pp.19, (2004)
 I. Tokuda, R.Tokunaga and K.Aihara,
"Back Propagation Learning of InfiniteDimensonal Dynamical Systems",
Neural Networks 16, pp.11791193 (2003)
 M.Kawamura, R.Tokunaga and M.Okada,
"Lowdimensional chaos induced by frustration in a nonmonotonic system",
Europhysics Letters, 62 (5), pp.657663 (2003)
 I. Tokuda, R. Tokunaga and T. Matsumoto
"Detecting Switching Dynamics in Chaotic TimeWaveform using a Parameterized Family of
Nonlinear Predictor",
Physica D , Physica D, vol. 135, pp.6378 (2000)
 R. Tokunaga and T. Matsumoto,
``A Nonlinear Prediction Technique for Parameterized Family of Chaotic Dynamics,''
International Journal of Intelligent Systems, vol.12, no.4, pp.291309 (1997).
 I. Tokuda, R. Tokunaga and K. Aihara,
``A Simple Geometrical Structure underlying Speech Signals of The Japanese Vowel /a/,''
International Journal of Bifurcation and Chaos, World Scientific, vol.6, no.1, January, pp.149160 (1996).
 I. Tokuda, S. Kajiwara, R. Tokunaga and T. Matsumoto,
``Recognizing Chaotic TimeWaveforms in Terms of A Parameterized Family of Nonlinear Predicotors,''
Physica D, vol. 95, pp.380395 (1996).
 R. Tokunaga, S. Kajiwara and T. Matsumoto,
``Reconstracting Bifurcation Diagrams only from TimeWaveforms,''
Physica 79D, pp.348360 (1994).
 R. Tokunaga, T. Matsumoto and Y. Abe,
``Observing A CodimensionTwo Heteroclinic Bifurcation,''
AIP, CHAOS, vol.3, no.1, pp.6372 (1993).
 M. Komuro, R. Tokunaga, T. Matsumoto, L. O. Chua and A. Hotta,
``Global Bifurcation Analysis of The Double Scroll Circuit,''
International Journal of Bifurcation and Chaos, World Scientific, vol.1, no.1, pp.139182, March (1991).
 R. Fujimoto, M. Komuro, R. Tokunaga and T. Matsumoto,
``A Hierarchical Structure in Homoclinic Bifurcations,''
The Transactions of the IEICE, vol.E73, no.6, pp.809816, June (1990).
 R. Tokunaga, T. Matsumoto, L. O. Chua and S. Miyama,
``The PiecewiseLinear Lorenz Circuit is Chaotic in the sense of Shilnikov,''
IEEE, Transactions on Circuits and Systems, vol.37, no.6, pp.766786, June (1990).
 R. Tokunaga, M. Komuro, T. Matumoto and L. O. Chua,
```Lorenz attractor' from an Electrical Circuit with Uncoupled PiecewiseLinear Resistors,''
International Journal of Circuit Theory and Applications, vol.17, no.1, pp.7185, January (1989).
 R. Tokunaga, L. O. Chua and T. Matumoto,
``Bifurcation Analysis of a CuspConstrained PiecewiseLinear Circuit,''
International Journal of Circuit Theory and Applications, vol.17, no.3, pp.283346, July (1989).
 T. Matumoto, L. O. Chua and R. Tokunaga,
``Chaos via Torus Breakdown,''
IEEE, Transactions on Circuits and Systems, vol.CAS34, no.3, pp.240253, March (1987).
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Proceedings
R. Tokunaga
``Image data processing based on contractive mapping and its inverse dynamics,''
Proceedings of the fourth asian fuzzy systems symposium, vol. 2/2, pp. 942945, 2000.
I. Tokudaa, R. Tokunaga and K. Aihara
``Adaptive Learning for Chaotic Optimization,''
Proceedings of the fourth asian fuzzy systems symposium, vol. 2/2, pp. 926932, 2000.
T. Takahashi and R. Tokunaga,
``Nonlinear Dimensionality Reduction by Multi Layer Perceptron Using Superposed Energy''
Proceedings of 1999 International Symposium on Nonlinear Theory and its Applications(NOLTA99),
vol. 2, pp. 863866, 1999.
T. Takahashi and R. Tokunaga,
``Energy Functions for Efficient Nonlinear Dimensionality Reduction by Multi Layer Perceptrons''
ICONIP'98 vol.1, pp.494497, 1998.
 T. Takahashi and R. Tokunaga,
``Removing the Redundancy of Perceptrons in Terms of a Simple Energy Function,''
Proceedings of the 1997 Internatinal Conference on Neural Information Processing and Intelligent Information Systems, vol.1/2, pp.271274 (1997).
 I. Tokuda, K. Aihara, R. Tokunaga, T. Nagashima,
``Learning algorithm for Chaotic Neural Networks which Solve Optimization Problems,''
Proceedings of The Symposium on Nonlinear Theory and its Applications (Hawaii) (1997) vol. 1/2 pp.617620 (1997)
 S. Kajiwara, I. Tokuda, R. Tokunaga and T. Matsumoto,
``Reconstructing Bifurcation Diagrams Only From TimeWaveforms,''
Proceedings of The 3rd International Conference on Fuzzy Logic and Neural Networks, Iizuka, pp.515517 August 17 (1994). (invited paper)
 R. Tokunaga,
``Controlling and Predicting Chaotic Dynamics,''
Proceedings of IEEE Symposium on Emerging Technologies and Factory Automation, Tokyo, pp.220224, November 610 (1994).
 I. Tokuda, R. Tokunaga and K. Aihara,
``Laryngeal vibrations: Towards understanding causes of irregularities in speech signals of vowel sounds,''
the Seventh TOYOTA Conference/Towards the Harnessing of Chaos, Mikkabi, October 31November 3 (1994).
(Proceedings : Towards the Harnessing of Chaos, Ed.by M.Yamaguchi, Elsevier, pp.413418 (1994).)
 R. Tokunaga, I. Tokuda, S. Kajiwara and T. Matsumoto,
``Reconstracting Bifurcation Diagrams only from TimeWaveforms,''
The international conference on Dynamical Syatems and Chaos, Tokyo, May 2327 (1994).
(Proceedings of the international conference on Dynamical Syatems and Chaos,
World Scientific, vol.2/2, pp.345354 (1994). (invited paper))
 T. Matsumoto, R. Tokunaga and M. Komuro,
``Global Bifurcations of the Double Scroll Circuit,''
Sumposium on Nonlinearity and Chaos in Engineering Dynamics, London, July 1923 (1993).
(Proceedings: Nonlinearity and Chaos in Engineering Dynamics, Edited by J. M. T. Thompson and S. R. Bishop, John Wiley & Sons Ltd, pp.421423 (1994). (invited paper))
 I. Tokuda, Y. Hirai and R. Tokunaga,
``Back Propagation Learning of an InfiniteDimensonal Dynamical System,''
Proceedings of International Joint Conference on Neural Networks, Nagoya,
vol.3/3, pp.22712275, October 2529 (1993).
 R. Tokunaga, T. Matsumoto and Y. Abe,
``Observing Codim2 Heteroclinic Bifurcations,''
Proceedings of Symposium on Nonlinear Theory and its Applications, Hakone, pp.107110, July 1416 (1992).
 R. Tokunaga,
``Fractal Image Coding Techniques Based on IFS,''
Proceedings of The 2nd International Conference on Fuzzy Logic and Neural Networks, Iizuka,vol.2/2, pp.951954, July 1722 (1992). (invited paper)
 M. Kawashima, R. Tokunaga and Y. Hirai,
``Contour Map Reconstruction via Multimudule Paralell Processing Computational Scheme,''
Proceedings of MVA'92, IAPR Workshop on Machine Vision Applications, Tokyo, pp.8791, December 79 (1992).
 W. Kim, T. Furukawa, Y. Hirai and R. Tokunaga,
"Extraction and Reconstraction of Road Segments by Spatial Filters,"
Proceedings of MVA'92, IAPR Workshop on Machine Vision Applications, Tokyo, pp.515518, December 79 (1992).
 R. Tokunaga, K. Miya, A. Hotta, R. Fujimoto, M. Komuro, T. Matumoto and L. O. Chua,
``Homoclinic Linkages : A New Bifurcation Mechanism,'' Proceedings of IEEE International Symposium on Circuits and Systems, Portland, vol.2, pp.826829, May 811 (1989). (invited paper)
 R. Tokunaga, M. Komuro, T. Matumoto and L. O. Chua,
```Lorenz attractor' from an Electrical Circuit with Uncoupled
PiecewiseLinear Resistors,'' Proceedings of IEEE International Symposium on Circuits and Systems, Philadelphia,vol.2/3,
pp.672675, May 47 (1987). (invited paper)
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Books (in English only)
 R.Tokunaga,``Bifurcations,'' SpringerVerlag (1993)
 R.Tokunaga,``Chaos in Circuits and Systems,'' World Scientific (2002)
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