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Ion Channeling in Quasicrystals

Plachke, D., Carstanjen, H. D.

In Quasicrystals. An Introduction to Structure, Physical Properties and Applications, 55, pages: 280-304, Springer Series in Materials Science, Springer, Berlin [et al.], 2002 (incollection)

mms

[BibTex]

[BibTex]


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Movement imitation with nonlinear dynamical systems in humanoid robots

Ijspeert, J. A., Nakanishi, J., Schaal, S.

In International Conference on Robotics and Automation (ICRA2002), Washinton, May 11-15 2002, 2002, clmc (inproceedings)

Abstract
Locally weighted learning (LWL) is a class of statistical learning techniques that provides useful representations and training algorithms for learning about complex phenomena during autonomous adaptive control of robotic systems. This paper introduces several LWL algorithms that have been tested successfully in real-time learning of complex robot tasks. We discuss two major classes of LWL, memory-based LWL and purely incremental LWL that does not need to remember any data explicitly. In contrast to the traditional beliefs that LWL methods cannot work well in high-dimensional spaces, we provide new algorithms that have been tested in up to 50 dimensional learning problems. The applicability of our LWL algorithms is demonstrated in various robot learning examples, including the learning of devil-sticking, pole-balancing of a humanoid robot arm, and inverse-dynamics learning for a seven degree-of-freedom robot.

am

link (url) [BibTex]

link (url) [BibTex]


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A locally weighted learning composite adaptive controller with structure adaptation

Nakanishi, J., Farrell, J. A., Schaal, S.

In IEEE International Conference on Intelligent Robots and Systems (IROS 2002), Lausanne, Sept.30-Oct.4 2002, 2002, clmc (inproceedings)

Abstract
This paper introduces a provably stable adaptive learning controller which employs nonlinear function approximation with automatic growth of the learning network according to the nonlinearities and the working domain of the control system. The unknown function in the dynamical system is approximated by piecewise linear models using a nonparametric regression technique. Local models are allocated as necessary and their parameters are optimized on-line. Inspired by composite adaptive control methods, the pro-posed learning adaptive control algorithm uses both the tracking error and the estimation error to up-date the parameters. We provide Lyapunov analyses that demonstrate the stability properties of the learning controller. Numerical simulations illustrate rapid convergence of the tracking error and the automatic structure adaptation capability of the function approximator. This paper introduces a provably stable adaptive learning controller which employs nonlinear function approximation with automatic growth of the learning network according to the nonlinearities and the working domain of the control system. The unknown function in the dynamical system is approximated by piecewise linear models using a nonparametric regression technique. Local models are allocated as necessary and their parameters are optimized on-line. Inspired by composite adaptive control methods, the pro-posed learning adaptive control algorithm uses both the tracking error and the estimation error to up-date the parameters. We provide Lyapunov analyses that demonstrate the stability properties of the learning controller. Numerical simulations illustrate rapid convergence of the tracking error and the automatic structure adaptation capability of the function approximator

am

link (url) [BibTex]

link (url) [BibTex]


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Nanomolding based fabrication of synthetic gecko foot-hairs

Sitti, M., Fearing, R. S.

In Nanotechnology, 2002. IEEE-NANO 2002. Proceedings of the 2002 2nd IEEE Conference on, pages: 137-140, 2002 (inproceedings)

pi

Project Page [BibTex]

Project Page [BibTex]


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Evidence for van der Waals adhesion in gecko setae

Autumn, K., Sitti, M., Liang, Y. A., Peattie, A. M., Hansen, W. R., Sponberg, S., Kenny, T. W., Fearing, R., Israelachvili, J. N., Full, R. J.

Proceedings of the National Academy of Sciences, 99(19):12252-12256, National Acad Sciences, 2002 (article)

pi

Project Page [BibTex]

Project Page [BibTex]


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Vacancies in thermal equilibrium and ferromagnetism near the Curie temperature

Seeger, A., Fähnle, M.

{Zeitschrift f\"ur Metallkunde}, 93(10):1030-1042, 2002 (article)

mms

[BibTex]

[BibTex]


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Magnetic imaging with soft X-ray microscopy

Fischer, P., Denbeaux, G., Eimüller, T., Goll, D., Schütz, G.

{IEEE Transactions on Magnetics}, 38(5):2427-2431, 2002 (article)

mms

[BibTex]

[BibTex]


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Theory of induced magnetic moments and x-ray magnetic circular dichroism in Co-Pt multilayers

Ederer, C., Komelj, M., Fähnle, M., Schütz, G.

{Physical Review B}, 66(9), 2002 (article)

mms

[BibTex]

[BibTex]


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Determination of the complete set of second-order magnetoelastic coupling constants on epitaxial films

Komelj, M., Fähnle, M.

{Physical Review B}, 65(21), 2002 (article)

mms

[BibTex]

[BibTex]


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Undulation instabilities in laterally structured magnetic multilayers

Eimüller, T., Scholz, M., Guttmann, P., Köhler, M., Bayreuther, G., Schmahl, G., Fischer, P., Schütz, G.

{Journal of Applied Physics}, 91(10):7334-7336, 2002 (article)

mms

[BibTex]

[BibTex]


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Initial oxidation of AlPdMn quasicrystals - A study by high-resolution RBS and ERDA

Plachke, D., Khellaf, A., Carstanjen, H. D.

{Nuclear Instruments \& Methods in Physics Research B}, 190, pages: 646-651, 2002 (article)

mms

[BibTex]

[BibTex]


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The Verwey transition - a topical review

Walz, F.

{Journal of Physics-Condensed Matter}, 14(12):R285-R340, 2002 (article)

mms

[BibTex]

[BibTex]


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Composition dependence of the Zener relaxation in high-purity FeCr single crystals

Hirscher, M., Ege, M.

{Materials \textquotesingleTransactions JIM}, 43(2):182-185, 2002 (article)

mms

[BibTex]

[BibTex]


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Hydrogen storage in carbon nanostructures

Hirscher, M., Becher, M., Haluska, M., Quintel, A., Skakalova, V., Choi, Y. M., Dettlaff-Weglikowska, U., Roth, S., Stepanek, I., Bernier, P., Leonhardt, A., Fink, J.

{Journal of Alloys and Compounds}, 330, pages: 654-658, 2002 (article)

mms

[BibTex]

[BibTex]


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Micromagnetism and the microstructure of the cell walls in Sm2Co17 based permanent magnets

Goll, D., Hadjipanayis, G. C., Kronmüller, H.

In Proceedings of the 17th International Workshop on Rare-Earth Magnets and their Applications, pages: 696-703, Rinton Press, Newark, Delaware, USA, 2002 (inproceedings)

mms

[BibTex]

[BibTex]


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Micromagnetic investigation of sub-100-nm magnetic domains in atomically stacked Fe(001)/Au(001) multilayers

Köhler, M., Zweck, J., Bayreuther, G., Fischer, P., Schütz, G., Denbeaux, G., Attwood, D.

{Journal of Magnetism and Magnetic Materials}, 240, pages: 79-82, 2002 (article)

mms

DOI [BibTex]

DOI [BibTex]


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Experimental Study of a Crystal Positron Source

Chehab, R., Cizeron, R., Sylvia, C., Baier, V., Beloborodov, K., Bukin, A., Burdin, S., Dimova, T., Drozdetsky, A., Druzhinin, V., Dubrovin, M., Golubev, V., Serednyakov, S., Shary, V., Strakhovenko, V., Artru, X., Chevallier, M., Dauvergne, D., Kirsch, R., Lautesse, P., Poizat, J. C., Remillieux, J., Jejcic, A., Keppler, P., Major, J., Gatignon, L., Bochek, G., Kulibaba, V., Maslov, N., Bogdanov, A., Potylitsin, A., Vnukov, I.

{Physics Letters B}, 525, pages: 41-48, 2002 (article)

mms

[BibTex]

[BibTex]


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Ab-initio study of the influence of epitaxial strain on magnetoelastic properties

Komelj, M., Fähnle, M.

In Atomistic Aspects of Epitaxial Growth, pages: 439-447, NATO Science series: Series 2, Mathematics, Physics, and Chemistry, Kluwer Academic Publishers, Dassia, Corfu [Greece], 2002 (inproceedings)

mms

[BibTex]

[BibTex]

1993


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Learning passive motor control strategies with genetic algorithms

Schaal, S., Sternad, D.

In 1992 Lectures in complex systems, pages: 913-918, (Editors: Nadel, L.;Stein, D.), Addison-Wesley, Redwood City, CA, 1993, clmc (inbook)

Abstract
This study investigates learning passive motor control strategies. Passive control is understood as control without active error correction; the movement is stabilized by particular properties of the controlling dynamics. We analyze the task of juggling a ball on a racket. An approximation to the optimal solution of the task is derived by means of optimization theory. In order to model the learning process, the problem is coded for a genetic algorithm in representations without sensory or with sensory information. For all representations the genetic algorithm is able to find passive control strategies, but learning speed and the quality of the outcome are significantly different. A comparison with data from human subjects shows that humans seem to apply yet different movement strategies to the ones proposed. For the feedback representation some implications arise for learning from demonstration.

am

link (url) [BibTex]

1993


link (url) [BibTex]


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A genetic algorithm for evolution from an ecological perspective

Sternad, D., Schaal, S.

In 1992 Lectures in Complex Systems, pages: 223-231, (Editors: Nadel, L.;Stein, D.), Addison-Wesley, Redwood City, CA, 1993, clmc (inbook)

Abstract
In the population model presented, an evolutionary dynamic is explored which is based on the operator characteristics of genetic algorithms. An essential modification in the genetic algorithms is the inclusion of a constraint in the mixing of the gene pool. The pairing for the crossover is governed by a selection principle based on a complementarity criterion derived from the theoretical tenet of perception-action (P-A) mutuality of ecological psychology. According to Swenson and Turvey [37] P-A mutuality underlies evolution and is an integral part of its thermodynamics. The present simulation tested the contribution of P-A-cycles in evolutionary dynamics. A numerical experiment compares the population's evolution with and without this intentional component. The effect is measured in the difference of the rate of energy dissipation, as well as in three operationalized aspects of complexity. The results support the predicted increase in the rate of energy dissipation, paralleled by an increase in the average heterogeneity of the population. Furthermore, the spatio-temporal evolution of the system is tested for the characteristic power-law relations of a nonlinear system poised in a critical state. The frequency distribution of consecutive increases in population size shows a significantly different exponent in functional relationship.

am

[BibTex]

[BibTex]


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Roles for memory-based learning in robotics

Atkeson, C. G., Schaal, S.

In Proceedings of the Sixth International Symposium on Robotics Research, pages: 503-521, Hidden Valley, PA, 1993, clmc (inproceedings)

am

[BibTex]

[BibTex]


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Design concurrent calculation: A CAD- and data-integrated approach

Schaal, S., Ehrlenspiel, K.

Journal of Engineering Design, 4, pages: 71-85, 1993, clmc (article)

Abstract
Besides functional regards, product design demands increasingly more for further reaching considerations. Quality alone cannot suffice anymore to compete in the market; design for manufacturability, for assembly, for recycling, etc., are well-known keywords. Those can largely be reduced to the necessity of design for costs. This paper focuses on a CAD-based approach to design concurrent calculation. It will discuss how, in the meantime well-established, tools like feature technology, knowledge-based systems, and relational databases can be blended into one coherent concept to achieve an entirely CAD- and data-integrated cost information tool. This system is able to extract data from the CAD-system, combine it with data about the company specific manufacturing environment, and subsequently autonomously evaluate manufacturability aspects and costs of the given CAD-model. Within minutes the designer gets quantitative in-formation about the major cost sources of his/her design. Additionally, some alternative methods for approximating manu-facturing times from empirical data, namely neural networks and local weighted regression, are introduced.

am

[BibTex]

[BibTex]


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Open loop stable control strategies for robot juggling

Schaal, S., Atkeson, C. G.

In IEEE International Conference on Robotics and Automation, 3, pages: 913-918, Piscataway, NJ: IEEE, Georgia, Atlanta, May 2-6, 1993, clmc (inproceedings)

Abstract
In a series of case studies out of the field of dynamic manipulation (Mason, 1992), different principles for open loop stable control are introduced and analyzed. This investigation may provide some insight into how open loop control can serve as a useful foundation for closed loop control and, particularly, what to focus on in learning control. 

am

link (url) [BibTex]

link (url) [BibTex]