Publications | Max Planck Institute for Intelligent Systems

2009

mms Honolka, J., Lee, T. Y., Kuhnke, K., Repetto, D., Sessi, V., Wahl, P., Buchsbaum, A., Varga, P., Gardonio, S., Carbone, C., Krishnakumar, S. R., Gambardella, P., Komelj, M., Singer, R., Fähnle, M., Fauth, K., Schütz, G., Enders, A., Kern, K. Complex magnetic phase in submonolayer Fe stripes on Pt(977) {Physical Review B}, 79, 2009 (article)

Local and nonlocal atomic contributions to unit-cell damping in near-adiabatic collinear magnetization dynamics

Seib, J., Steiauf, D., Fähnle, M.

{Physical Review B}, 79, 2009 (article)

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mms Seib, J., Steiauf, D., Fähnle, M. Local and nonlocal atomic contributions to unit-cell damping in near-adiabatic collinear magnetization dynamics {Physical Review B}, 79, 2009 (article)

Temperature-dependent critical currents in superconducting YBa2Cu3O7-δand ferromagnetic La2/3Ca1/3MnO3 hybrid structures

Djupmyr, M., Soltan, S., Habermeier, H.-U., Albrecht, J.

{Physical Review B}, 80, 2009 (article)

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mms Djupmyr, M., Soltan, S., Habermeier, H.-U., Albrecht, J. Temperature-dependent critical currents in superconducting YBa2Cu3O7-δand ferromagnetic La2/3Ca1/3MnO3 hybrid structures {Physical Review B}, 80, 2009 (article)

High surface area polyHIPEs with hierarchical pore system

Schwab, M. G., Senkovska, I., Rose, M., Klein, N., Koch, M., Pahnke, J., Jonschker, G., Schmitz, B., Hirscher, M., Kaskel, S.

{Soft Matter}, 5, pages: 1055-1059, 2009 (article)

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mms Schwab, M. G., Senkovska, I., Rose, M., Klein, N., Koch, M., Pahnke, J., Jonschker, G., Schmitz, B., Hirscher, M., Kaskel, S. High surface area polyHIPEs with hierarchical pore system {Soft Matter}, 5, pages: 1055-1059, 2009 (article)

Grain boundary wetting phase transformations in the Zn-Sn and Zn-In systems

Gornakova, A. S., Straumal, B. B., Tsurekawa, S., Chang, L.-S., Nekrasov, A. N.

{Reviews on Advanced Materials Science}, 21(1):18-26, 2009 (article)

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mms Gornakova, A. S., Straumal, B. B., Tsurekawa, S., Chang, L.-S., Nekrasov, A. N. Grain boundary wetting phase transformations in the Zn-Sn and Zn-In systems {Reviews on Advanced Materials Science}, 21(1):18-26, 2009 (article)

Magnetization study of nanograined pure and Mn-doped ZnO films: formation of a ferromagnetic grain-boundary foam

Straumal, B. B., Mazilkin, A. A., Protasova, S. G., Myatiev, A. A., Straumal, P. B., Schütz, G., van Aken, P. A., Goering, E., Baretzky, B.

{Physical Review B}, 79, 2009 (article)

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mms Straumal, B. B., Mazilkin, A. A., Protasova, S. G., Myatiev, A. A., Straumal, P. B., Schütz, G., van Aken, P. A., Goering, E., Baretzky, B. Magnetization study of nanograined pure and Mn-doped ZnO films: formation of a ferromagnetic grain-boundary foam {Physical Review B}, 79, 2009 (article)

In situ synthesis and hydrogen storage properties of PdNi alloy nanoparticles in an ordered mesoporous carbon template

Campesi, R., Cuevas, F., Leroy, E., Hirscher, M., Gadiou, R., Vix-Guterl, C., Latroche, M.

{Microporous and Mesoporous Materials}, 117, pages: 511-514, 2009 (article)

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mms Campesi, R., Cuevas, F., Leroy, E., Hirscher, M., Gadiou, R., Vix-Guterl, C., Latroche, M. In situ synthesis and hydrogen storage properties of PdNi alloy nanoparticles in an ordered mesoporous carbon template {Microporous and Mesoporous Materials}, 117, pages: 511-514, 2009 (article)

On-line learning and modulation of periodic movements with nonlinear dynamical systems

Gams, A., Ijspeert, A., Schaal, S., Lenarčič, J.

Autonomous Robots, 27(1):3-23, 2009, clmc (article)

Abstract

Abstract The paper presents a two-layered system for (1) learning and encoding a periodic signal without any knowledge on its frequency and waveform, and (2) modulating the learned periodic trajectory in response to external events. The system is used to learn periodic tasks on a humanoid HOAP-2 robot. The first layer of the system is a dynamical system responsible for extracting the fundamental frequency of the input signal, based on adaptive frequency oscillators. The second layer is a dynamical system responsible for learning of the waveform based on a built-in learning algorithm. By combining the two dynamical systems into one system we can rapidly teach new trajectories to robots without any knowledge of the frequency of the demonstration signal. The system extracts and learns only one period of the demonstration signal. Furthermore, the trajectories are robust to perturbations and can be modulated to cope with a dynamic environment. The system is computationally inexpensive, works on-line for any periodic signal, requires no additional signal processing to determine the frequency of the input signal and can be applied in parallel to multiple dimensions. Additionally, it can adapt to changes in frequency and shape, e.g. to non-stationary signals, such as hand-generated signals and human demonstrations.

am Gams, A., Ijspeert, A., Schaal, S., Lenarčič, J. On-line learning and modulation of periodic movements with nonlinear dynamical systems Autonomous Robots, 27(1):3-23, 2009, clmc (article)

Local dimensionality reduction for non-parametric regression

Hoffman, H., Schaal, S., Vijayakumar, S.

Neural Processing Letters, 2009, clmc (article)

Abstract

Locally-weighted regression is a computationally-efficient technique for non-linear regression. However, for high-dimensional data, this technique becomes numerically brittle and computationally too expensive if many local models need to be maintained simultaneously. Thus, local linear dimensionality reduction combined with locally-weighted regression seems to be a promising solution. In this context, we review linear dimensionality-reduction methods, compare their performance on nonparametric locally-linear regression, and discuss their ability to extend to incremental learning. The considered methods belong to the following three groups: (1) reducing dimensionality only on the input data, (2) modeling the joint input-output data distribution, and (3) optimizing the correlation between projection directions and output data. Group 1 contains principal component regression (PCR); group 2 contains principal component analysis (PCA) in joint input and output space, factor analysis, and probabilistic PCA; and group 3 contains reduced rank regression (RRR) and partial least squares (PLS) regression. Among the tested methods, only group 3 managed to achieve robust performance even for a non-optimal number of components (factors or projection directions). In contrast, group 1 and 2 failed for fewer components since these methods rely on the correct estimate of the true intrinsic dimensionality. In group 3, PLS is the only method for which a computationally-efficient incremental implementation exists. Thus, PLS appears to be ideally suited as a building block for a locally-weighted regressor in which projection directions are incrementally added on the fly.

am Hoffman, H., Schaal, S., Vijayakumar, S. Local dimensionality reduction for non-parametric regression Neural Processing Letters, 2009, clmc (article)

Enhanced adhesion by gecko-inspired hierarchical fibrillar adhesives

Murphy, M. P., Kim, S., Sitti, M.

ACS applied materials \& interfaces, 1(4):849-855, American Chemical Society, 2009 (article)

pi Murphy, M. P., Kim, S., Sitti, M. Enhanced adhesion by gecko-inspired hierarchical fibrillar adhesives ACS applied materials \& interfaces, 1(4):849-855, American Chemical Society, 2009 (article)

Miniature devices: Voyage of the microrobots

Sitti, M.

Nature, 458(7242):1121-1122, Nature Publishing Group, 2009 (article)

pi Sitti, M. Miniature devices: Voyage of the microrobots Nature, 458(7242):1121-1122, Nature Publishing Group, 2009 (article)

Dry spinning based spinneret based tunable engineered parameters (STEP) technique for controlled and aligned deposition of polymeric nanofibers

Nain, A. S., Sitti, M., Jacobson, A., Kowalewski, T., Amon, C.

Macromolecular rapid communications, 30(16):1406-1412, WILEY-VCH Verlag, 2009 (article)

pi Nain, A. S., Sitti, M., Jacobson, A., Kowalewski, T., Amon, C. Dry spinning based spinneret based tunable engineered parameters (STEP) technique for controlled and aligned deposition of polymeric nanofibers Macromolecular rapid communications, 30(16):1406-1412, WILEY-VCH Verlag, 2009 (article)

Two-dimensional contact and noncontact micromanipulation in liquid using an untethered mobile magnetic microrobot

Floyd, S., Pawashe, C., Sitti, M.

IEEE Transactions on Robotics, 25(6):1332-1342, IEEE, 2009 (article)

pi Floyd, S., Pawashe, C., Sitti, M. Two-dimensional contact and noncontact micromanipulation in liquid using an untethered mobile magnetic microrobot IEEE Transactions on Robotics, 25(6):1332-1342, IEEE, 2009 (article)

Mit Röntgenblitzen zu neuen Erkenntnissen

Hedderich, R., Weigand, M., Baretzky, B.

{Nanotechnik - Molek\"ule Materialien Mikrosysteme}, (6 (Beilage zu Photonik 41. 2009)), 2009 (article)

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mms Hedderich, R., Weigand, M., Baretzky, B. Mit Röntgenblitzen zu neuen Erkenntnissen {Nanotechnik - Molek\"ule Materialien Mikrosysteme}, (6 (Beilage zu Photonik 41. 2009)), 2009 (article)

Second-order faceting-roughening of the tilt grain boundary in zinc

Straumal, B. B., Gornakova, A. S., Sursaeva, V. G., Yashnikov, V. P.

{International Journal of Materials Research}, 100(4):525-529, 2009 (article)

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mms Straumal, B. B., Gornakova, A. S., Sursaeva, V. G., Yashnikov, V. P. Second-order faceting-roughening of the tilt grain boundary in zinc {International Journal of Materials Research}, 100(4):525-529, 2009 (article)

Improvement of interface structure and magnetic properties of Co on Si (100) by surfactant (Sb) mediated growth

Dash, S. P., Goll, D., Carstanjen, H. D.

{Applied Physics A}, 97(3):651-656, 2009 (article)

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mms Dash, S. P., Goll, D., Carstanjen, H. D. Improvement of interface structure and magnetic properties of Co on Si (100) by surfactant (Sb) mediated growth {Applied Physics A}, 97(3):651-656, 2009 (article)

Effect of severe plastic deformation on the coercivity of Co-Cu alloys

Straumal, B. B., Protasova, S. G., Mazilkin, A. A., Baretzky, B., Goll, D., Gunderov, D. V., Valiev, R. Z.

{Philosophical Magazine Letters}, 89(10):649-654, 2009 (article)

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mms Straumal, B. B., Protasova, S. G., Mazilkin, A. A., Baretzky, B., Goll, D., Gunderov, D. V., Valiev, R. Z. Effect of severe plastic deformation on the coercivity of Co-Cu alloys {Philosophical Magazine Letters}, 89(10):649-654, 2009 (article)

Magnetic properties of cobalt-covered MgB2 films

Treiber, S., Stuhlhofer, B., Habermeier, H.-U., Albrecht, J.

{Superconductor Science and Technology}, 22, 2009 (article)

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mms Treiber, S., Stuhlhofer, B., Habermeier, H.-U., Albrecht, J. Magnetic properties of cobalt-covered MgB2 films {Superconductor Science and Technology}, 22, 2009 (article)

Reconstruction of historic alloys for pipe organs brings true Baroque music back to life

Baretzky, B., Friesel, M., Straumal, B.

{Japan Organist}, 36, pages: 29-38, 2009 (article)

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mms Baretzky, B., Friesel, M., Straumal, B. Reconstruction of historic alloys for pipe organs brings true Baroque music back to life {Japan Organist}, 36, pages: 29-38, 2009 (article)

Exchange-coupled L10-FePt/Fe composite patterns with perpendicular magnetization

Breitling, A., Bublat, T., Goll, D.

{Physica Status Solidi - Rapid Research Letters}, 3(5):130-132, 2009 (article)

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mms Breitling, A., Bublat, T., Goll, D. Exchange-coupled L10-FePt/Fe composite patterns with perpendicular magnetization {Physica Status Solidi - Rapid Research Letters}, 3(5):130-132, 2009 (article)

Proton NMR studies of the NaAlH4 structure

Valiente-Banuet, L. E., Majer, G., Müller, K.

{Journal of Magnetic Resonance}, 200, pages: 280-284, 2009 (article)

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mms Valiente-Banuet, L. E., Majer, G., Müller, K. Proton NMR studies of the NaAlH4 structure {Journal of Magnetic Resonance}, 200, pages: 280-284, 2009 (article)

A scaled bilateral control system for experimental one-dimensional teleoperated nanomanipulation

Onal, C. D., Sitti, M.

The International Journal of Robotics Research, 28(4):484-497, Sage Publications, 2009 (article)

pi Onal, C. D., Sitti, M. A scaled bilateral control system for experimental one-dimensional teleoperated nanomanipulation The International Journal of Robotics Research, 28(4):484-497, Sage Publications, 2009 (article)

A Swallowable Tethered Capsule Endoscope for Diagnosing Barrett’s Esophagus

Glass, P., Sitti, M., Pennathur, A., Appasamy, R.

Gastrointestinal Endoscopy, 69(5):AB106, Mosby, 2009 (article)

pi Glass, P., Sitti, M., Pennathur, A., Appasamy, R. A Swallowable Tethered Capsule Endoscope for Diagnosing Barrett’s Esophagus Gastrointestinal Endoscopy, 69(5):AB106, Mosby, 2009 (article)

Adhesion of biologically inspired polymer microfibers on soft surfaces

Cheung, E., Sitti, M.

Langmuir, 25(12):6613-6616, ACS Publications, 2009 (article)

pi Cheung, E., Sitti, M. Adhesion of biologically inspired polymer microfibers on soft surfaces Langmuir, 25(12):6613-6616, ACS Publications, 2009 (article)

Dangling chain elastomers as repeatable fibrillar adhesives

Sitti, M., Cusick, B., Aksak, B., Nese, A., Lee, H., Dong, H., Kowalewski, T., Matyjaszewski, K.

ACS applied materials \& interfaces, 1(10):2277-2287, American Chemical Society, 2009 (article)

pi Sitti, M., Cusick, B., Aksak, B., Nese, A., Lee, H., Dong, H., Kowalewski, T., Matyjaszewski, K. Dangling chain elastomers as repeatable fibrillar adhesives ACS applied materials \& interfaces, 1(10):2277-2287, American Chemical Society, 2009 (article)

A Sensor-Based Learning Algorithm for the Self-Organization of Robot Behavior

Hesse, F., Martius, G., Der, R., Herrmann, J. M.

Algorithms, 2(1):398-409, 2009 (article)

Abstract

Ideally, sensory information forms the only source of information to a robot. We consider an algorithm for the self-organization of a controller. At short timescales the controller is merely reactive but the parameter dynamics and the acquisition of knowledge by an internal model lead to seemingly purposeful behavior on longer timescales. As a paradigmatic example, we study the simulation of an underactuated snake-like robot. By interacting with the real physical system formed by the robotic hardware and the environment, the controller achieves a sensitive and body-specific actuation of the robot.

al Hesse, F., Martius, G., Der, R., Herrmann, J. M. A Sensor-Based Learning Algorithm for the Self-Organization of Robot Behavior Algorithms, 2(1):398-409, 2009 (article)

Magnetism of FePt surface alloys

Honolka, J., Lee, T. Y., Kuhnke, K., Enders, A., Skomski, R., Bornemann, S., Mankovsky, S., Minár, J., Staunton, J., Ebert, H., Hessler, M., Fauth, K., Schütz, G., Buchsbaum, A., Schmid, M., Varga, P., Kern, K.

{Physical Review Letters}, 102(6), 2009 (article)

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mms Honolka, J., Lee, T. Y., Kuhnke, K., Enders, A., Skomski, R., Bornemann, S., Mankovsky, S., Minár, J., Staunton, J., Ebert, H., Hessler, M., Fauth, K., Schütz, G., Buchsbaum, A., Schmid, M., Varga, P., Kern, K. Magnetism of FePt surface alloys {Physical Review Letters}, 102(6), 2009 (article)

Enhanced 95Zr diffusion in grain boundaries of nano-crystalline ZrO2 \mbox⋅ 9.5 mol\textpercent Y2O3

Drings, H., Brossmann, U., Carstanjen, H. D., Szökefalvi-Nagy, A., Noll, C., Schaefer, H.-E.

{Physica Status Solidi (A)}, 206(1):54-58, 2009 (article)

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mms Drings, H., Brossmann, U., Carstanjen, H. D., Szökefalvi-Nagy, A., Noll, C., Schaefer, H.-E. Enhanced 95Zr diffusion in grain boundaries of nano-crystalline ZrO2 \mbox⋅ 9.5 mol\textpercent Y2O3 {Physica Status Solidi (A)}, 206(1):54-58, 2009 (article)

Magnetism of nanostructured materials for advanced magnetic recording

Goll, D.

{International Journal of Materials Research}, 100, pages: 652-662, 2009 (article)

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mms Goll, D. Magnetism of nanostructured materials for advanced magnetic recording {International Journal of Materials Research}, 100, pages: 652-662, 2009 (article)

Vortex core switching by coherent excitation with single in-plane magnetic field pulses

Weigand, M., van Waeyenberge, B., Vansteenkiste, A., Curcic, M., Sackmann, V., Stoll, H., Tyliszczak, T., Kaznatcheev, K., Bertwistle, D., Woltersdorf, G., Back, C. H., Schütz, G.

{Physical Review Letters}, 102, 2009 (article)

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mms Weigand, M., van Waeyenberge, B., Vansteenkiste, A., Curcic, M., Sackmann, V., Stoll, H., Tyliszczak, T., Kaznatcheev, K., Bertwistle, D., Woltersdorf, G., Back, C. H., Schütz, G. Vortex core switching by coherent excitation with single in-plane magnetic field pulses {Physical Review Letters}, 102, 2009 (article)

Increase of Mn solubility with decreasing grain size in ZnO

Straumal, B., Baretzky, B., Mazilkin, A., Protasova, S., Myatiev, A., Straumal, P.

{Journal of the European Ceramic Society}, 29(10):1963-1970, 2009 (article)

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mms Straumal, B., Baretzky, B., Mazilkin, A., Protasova, S., Myatiev, A., Straumal, P. Increase of Mn solubility with decreasing grain size in ZnO {Journal of the European Ceramic Society}, 29(10):1963-1970, 2009 (article)

Fe-C nanograined alloys obtained by high-pressure torsion: Structure and magnetic properties

Straumal, B. B., Mazilkin, A. A., Protasova, S. G., Dobatkin, S. V., Rodin, A. O., Baretzky, B., Goll, D., Schütz, G.

{Materials Science and Engineering A}, 503, pages: 185-189, 2009 (article)

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mms Straumal, B. B., Mazilkin, A. A., Protasova, S. G., Dobatkin, S. V., Rodin, A. O., Baretzky, B., Goll, D., Schütz, G. Fe-C nanograined alloys obtained by high-pressure torsion: Structure and magnetic properties {Materials Science and Engineering A}, 503, pages: 185-189, 2009 (article)

Chiral symmetry breaking of magnetic vortices by sample roughness

Vansteenkiste, A., Weigand, M., Curcic, M., Stoll, H., Schütz, G., Van Waeyenberge, B.

{New Journal of Physics}, 11, 2009 (article)

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mms Vansteenkiste, A., Weigand, M., Curcic, M., Stoll, H., Schütz, G., Van Waeyenberge, B. Chiral symmetry breaking of magnetic vortices by sample roughness {New Journal of Physics}, 11, 2009 (article)

Extended s-d model for magnetization dynamics of strongly noncollinear configurations

De Angeli, L., Steiauf, D., Singer, R., Köberle, I., Dietermann, F., Fähnle, M.

{Physical Review B}, 79, 2009 (article)

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mms De Angeli, L., Steiauf, D., Singer, R., Köberle, I., Dietermann, F., Fähnle, M. Extended s-d model for magnetization dynamics of strongly noncollinear configurations {Physical Review B}, 79, 2009 (article)

Incorporating Muscle Activation-Contraction dynamics to an optimal control framework for finger movements

Theodorou, Evangelos A., Valero-Cuevas, Francisco J.

Abstracts of Neural Control of Movement Conference (NCM 2009), 2009, clmc (article)

Abstract

Recent experimental and theoretical work [1] investigated the neural control of contact transition between motion and force during tapping with the index finger as a nonlinear optimization problem. Such transitions from motion to well-directed contact force are a fundamental part of dexterous manipulation. There are 3 alternative hypotheses of how this transition could be accomplished by the nervous system as a function of changes in direction and magnitude of the torque vector controlling the finger. These hypotheses are 1) an initial change in direction with a subsequent change in magnitude of the torque vector; 2) an initial change in magnitude with a subsequent directional change of the torque vector; and 3) a simultaneous and proportionally equal change of both direction and magnitude of the torque vector. Experimental work in [2] shows that the nervous system selects the first strategy, and in [1] we suggest that this may in fact be the optimal strategy. In [4] the framework of Iterative Linear Quadratic Optimal Regulator (ILQR) was extended to incorporate motion and force control. However, our prior simulation work assumed direct and instantaneous control of joint torques, which ignores the known delays and filtering properties of skeletal muscle. In this study, we implement an ILQR controller for a more biologically plausible biomechanical model of the index finger than [4], and add activation-contraction dynamics to the system to simulate muscle function. The planar biomechanical model includes the kinematics of the 3 joints while the applied torques are driven by activation?contraction dynamics with biologically plausible time constants [3]. In agreement with our experimental work [2], the task is to, within 500 ms, move the finger from a given resting configuration to target configuration with a desired terminal velocity. ILQR does not only stabilize the finger dynamics according to the objective function, but it also generates smooth joint space trajectories with minimal tuning and without an a-priori initial control policy (which is difficult to find for highly dimensional biomechanical systems). Furthemore, the use of this optimal control framework and the addition of activation-contraction dynamics considers the full nonlinear dynamics of the index finger and produces a sequence of postures which are compatible with experimental motion data [2]. These simulations combined with prior experimental results suggest that optimal control is a strong candidate for the generation of finger movements prior to abrupt motion-to-force transitions. This work is funded in part by grants NIH R01 0505520 and NSF EFRI-0836042 to Dr. Francisco J. Valero- Cuevas 1 Venkadesan M, Valero-Cuevas FJ.  Effects of neuromuscular lags on controlling contact transitions.  Philosophical Transactions of the Royal Society A: 2008. 2 Venkadesan M, Valero-Cuevas FJ.  Neural Control of Motion-to-Force Transitions with the Fingertip.  J. Neurosci., Feb 2008; 28: 1366 - 1373; 3 Zajac. Muscle and tendon: properties, models, scaling, and application to biomechanics and motor control. Crit Rev Biomed Eng, 17 4. Weiwei Li., Francisco Valero Cuevas: ?Linear Quadratic Optimal Control of Contact Transition with Fingertip ? ACC 2009

PDF [BibTex]

am Theodorou, Evangelos A., Valero-Cuevas, Francisco J. Incorporating Muscle Activation-Contraction dynamics to an optimal control framework for finger movements Abstracts of Neural Control of Movement Conference (NCM 2009), 2009, clmc (article)

PDF [BibTex]

On-line learning and modulation of periodic movements with nonlinear dynamical systems

Gams, A., Ijspeert, A., Schaal, S., Lenarčič, J.

Autonomous Robots, 27(1):3-23, 2009, clmc (article)

Abstract

am Gams, A., Ijspeert, A., Schaal, S., Lenarčič, J. On-line learning and modulation of periodic movements with nonlinear dynamical systems Autonomous Robots, 27(1):3-23, 2009, clmc (article)

Reversible dry micro-fibrillar adhesives with thermally controllable adhesion

Kim, S., Sitti, M., Xie, T., Xiao, X.

Soft Matter, 5(19):3689-3693, Royal Society of Chemistry, 2009 (article)

pi Kim, S., Sitti, M., Xie, T., Xiao, X. Reversible dry micro-fibrillar adhesives with thermally controllable adhesion Soft Matter, 5(19):3689-3693, Royal Society of Chemistry, 2009 (article)

Enhanced reversible adhesion of dopamine methacrylamide-coated elastomer microfibrillar structures under wet conditions

Glass, P., Chung, H., Washburn, N. R., Sitti, M.

Langmuir, 25(12):6607-6612, ACS Publications, 2009 (article)

pi Glass, P., Chung, H., Washburn, N. R., Sitti, M. Enhanced reversible adhesion of dopamine methacrylamide-coated elastomer microfibrillar structures under wet conditions Langmuir, 25(12):6607-6612, ACS Publications, 2009 (article)

Superconducting phase formation in random neck syntheses: a study of the Y-Ba-Cu-O system by magneto-optics and magnetometry

Willems, J. B., Albrecht, J., Landau, I. L., Hulliger, J.

{Superconductor Science and Technology}, 22, 2009 (article)

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mms Willems, J. B., Albrecht, J., Landau, I. L., Hulliger, J. Superconducting phase formation in random neck syntheses: a study of the Y-Ba-Cu-O system by magneto-optics and magnetometry {Superconductor Science and Technology}, 22, 2009 (article)

Determination of spin moments from magnetic EXAFS

Popescu, V., Gü\ssmann, M., Fähnle, M., Schütz, G.

{Physical Review B}, 79, 2009 (article)

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mms Popescu, V., Gü\ssmann, M., Fähnle, M., Schütz, G. Determination of spin moments from magnetic EXAFS {Physical Review B}, 79, 2009 (article)

Linewidth of ferromagnetic resonance for systems with anisotropic damping

Seib, J., Steiauf, D., Fähnle, M.

{Physical Review B}, 79, 2009 (article)

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mms Seib, J., Steiauf, D., Fähnle, M. Linewidth of ferromagnetic resonance for systems with anisotropic damping {Physical Review B}, 79, 2009 (article)

Structural and magnetic deconvolution of FePt/FeOx-nanoparticles using x-ray magnetic circular dichroism

Nolle, D., Goering, E., Tietze, T., Schütz, G., Figuerola, A., Manna, L.

{New Journal of Physics}, 11, 2009 (article)

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mms Nolle, D., Goering, E., Tietze, T., Schütz, G., Figuerola, A., Manna, L. Structural and magnetic deconvolution of FePt/FeOx-nanoparticles using x-ray magnetic circular dichroism {New Journal of Physics}, 11, 2009 (article)

Magnetic imaging with femtosecond temporal resolution

Li, J., Lee, M.-S., He, W., Redeker, B., Remhof, A., Amaladass, E., Hassel, C., Eimüller, T.

{Review of Scientific Instruments}, 80(7), 2009 (article)

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mms Li, J., Lee, M.-S., He, W., Redeker, B., Remhof, A., Amaladass, E., Hassel, C., Eimüller, T. Magnetic imaging with femtosecond temporal resolution {Review of Scientific Instruments}, 80(7), 2009 (article)

Elliott-Yafet mechanism and the discussion of femtosecond magnetization dynamics

Steiauf, D., Fähnle, M.

{Physical Review B}, 79, 2009 (article)

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mms Steiauf, D., Fähnle, M. Elliott-Yafet mechanism and the discussion of femtosecond magnetization dynamics {Physical Review B}, 79, 2009 (article)

Investigation of the stability of Mn12 single molecule magnets

Voss, S., Fonin, M., Burova, L., Burgert, M., Dedkov, Y. S., Preobrajenski, A. B., Goering, E., Groth, U., Kaul, A. R., Ruediger, U.

{Applied Physics A}, 94(3):491-495, 2009 (article)

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mms Voss, S., Fonin, M., Burova, L., Burgert, M., Dedkov, Y. S., Preobrajenski, A. B., Goering, E., Groth, U., Kaul, A. R., Ruediger, U. Investigation of the stability of Mn12 single molecule magnets {Applied Physics A}, 94(3):491-495, 2009 (article)

2008

Modelling contrast discrimination data suggest both the pedestal effect and stochastic resonance to be caused by the same mechanism

Goris, R., Wagemans, J., Wichmann, F.

Journal of Vision, 8(15):1-21, November 2008 (article)

Abstract

Computational models of spatial vision typically make use of a (rectified) linear filter, a nonlinearity and dominant late noise to account for human contrast discrimination data. Linear–nonlinear cascade models predict an improvement in observers' contrast detection performance when low, subthreshold levels of external noise are added (i.e., stochastic resonance). Here, we address the issue whether a single contrast gain-control model of early spatial vision can account for both the pedestal effect, i.e., the improved detectability of a grating in the presence of a low-contrast masking grating, and stochastic resonance. We measured contrast discrimination performance without noise and in both weak and moderate levels of noise. Making use of a full quantitative description of our data with few parameters combined with comprehensive model selection assessments, we show the pedestal effect to be more reduced in the presence of weak noise than in moderate noise. This reduction rules out independent, additive sources of performance improvement and, together with a simulation study, supports the parsimonious explanation that a single mechanism underlies the pedestal effect and stochastic resonance in contrast perception.

Web DOI [BibTex]

2008

ei Goris, R., Wagemans, J., Wichmann, F. Modelling contrast discrimination data suggest both the pedestal effect and stochastic resonance to be caused by the same mechanism Journal of Vision, 8(15):1-21, November 2008 (article)

Web DOI [BibTex]

gBoost: A Mathematical Programming Approach to Graph Classification and Regression

Saigo, H., Nowozin, S., Kadowaki, T., Kudo, T., Tsuda, K.

Machine Learning, 75(1):69-89, November 2008 (article)

Abstract

Graph mining methods enumerate frequently appearing subgraph patterns, which can be used as features for subsequent classification or regression. However, frequent patterns are not necessarily informative for the given learning problem. We propose a mathematical programming boosting method (gBoost) that progressively collects informative patterns. Compared to AdaBoost, gBoost can build the prediction rule with fewer iterations. To apply the boosting method to graph data, a branch-and-bound pattern search algorithm is developed based on the DFS code tree. The constructed search space is reused in later iterations to minimize the computation time. Our method can learn more efficiently than the simpler method based on frequent substructure mining, because the output labels are used as an extra information source for pruning the search space. Furthermore, by engineering the mathematical program, a wide range of machine learning problems can be solved without modifying the pattern search algorithm.

ei Saigo, H., Nowozin, S., Kadowaki, T., Kudo, T., Tsuda, K. gBoost: A Mathematical Programming Approach to Graph Classification and Regression Machine Learning, 75(1):69-89, November 2008 (article)

Steinke, F., Schölkopf, B.

Variational Bayesian Model Selection in Linear Gaussian State-Space based Models

Chiappa, S.

International Workshop on Flexible Modelling: Smoothing and Robustness (FMSR 2008), 2008, pages: 1, November 2008 (poster)

Web [BibTex]

ei Chiappa, S. Variational Bayesian Model Selection in Linear Gaussian State-Space based Models International Workshop on Flexible Modelling: Smoothing and Robustness (FMSR 2008), 2008, pages: 1, November 2008 (poster)

Web [BibTex]

Machine Learning for Motor Skills in Robotics

Peters, J.

K{\"u}nstliche Intelligenz, 2008(4):41-43, November 2008 (article)

Abstract

Autonomous robots that can adapt to novel situations has been a long standing vision of robotics, artificial intelligence, and the cognitive sciences. Early approaches to this goal during the heydays of artificial intelligence research in the late 1980s, however, made it clear that an approach purely based on reasoning or human insights would not be able to model all the perceptuomotor tasks of future robots. Instead, new hope was put in the growing wake of machine learning that promised fully adaptive control algorithms which learn both by observation and trial-and-error. However, to date, learning techniques have yet to fulfill this promise as only few methods manage to scale into the high-dimensional domains of manipulator and humanoid robotics and usually scaling was only achieved in precisely pre-structured domains. We have investigated the ingredients for a general approach to motor skill learning in order to get one step closer towards human-like performance. For doing so, we study two major components for such an approach, i.e., firstly, a theoretically well-founded general approach to representing the required control structures for task representation and execution and, secondly, appropriate learning algorithms which can be applied in this setting.

PDF Web [BibTex]

ei Peters, J. Machine Learning for Motor Skills in Robotics K{\"u}nstliche Intelligenz, 2008(4):41-43, November 2008 (article)

PDF Web [BibTex]

Kernels, Regularization and Differential Equations

Pattern Recognition, 41(11):3271-3286, November 2008 (article)

Abstract

Many common machine learning methods such as Support Vector Machines or Gaussian process inference make use of positive definite kernels, reproducing kernel Hilbert spaces, Gaussian processes, and regularization operators. In this work these objects are presented in a general, unifying framework, and interrelations are highlighted. With this in mind we then show how linear stochastic differential equation models can be incorporated naturally into the kernel framework. And vice versa, many kernel machines can be interpreted in terms of differential equations. We focus especially on ordinary differential equations, also known as dynamical systems, and it is shown that standard kernel inference algorithms are equivalent to Kalman filter methods based on such models. In order not to cloud qualitative insights with heavy mathematical machinery, we restrict ourselves to finite domains, implying that differential equations are treated via their corresponding finite difference equations.

ei Steinke, F., Schölkopf, B. Kernels, Regularization and Differential Equations Pattern Recognition, 41(11):3271-3286, November 2008 (article)