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2003


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Cluster expansion technique: An efficient tool to search for ground-state configurations of adatoms on plane surfaces

Drautz, R., Singer, R., Fähnle, M.

{Physical Review B}, 67, 2003 (article)

mms

[BibTex]

2003



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Hydrogen strorage in carbon nanotubes

Becher, M., Haluska, M., Hirscher, M., Quintel, A., Skakalova, V., Dettlaff-Weglikovska, U., Chen, X., Hulman, M., Choi, Y., Roth, S., Meregalli, V., Parrinello, M., Ströbel, R., Jörissen, L., Kappes, M., Fink, J., Züttel, A., Stepanek, I., Bernier, P.

{Comptes Rendus Physique}, 4, pages: 1055-1062, 2003 (article)

mms

[BibTex]

[BibTex]


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Grain boundary faceting phase transition and thermal grooving in Cu

Straumal, B. B., Polyakov, S. A., Bischoff, E., Mittemeijer, E. J., Gust, W.

In Proceedings of the International Conference on Diffusion, Segregation and Stresses in Materials, 216/217, pages: 93-100, Diffusion and Defect Data, Pt. A, Defect and Diffusion Forum, Scitec Publ., Moscow, 2003 (inproceedings)

mms

[BibTex]

[BibTex]


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Thermal desorption spectroscopy as a quantitative tool to determine the hydrogen content in solids

von Zeppelin, F., Haluska, M., Hirscher, M.

{Thermochimica Acta}, 404, pages: 251-258, 2003 (article)

mms

[BibTex]

[BibTex]


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Surface adsorbed atoms suppressing hydrogen permeation of Pd membranes

Yamakawa, K., Ege, M., Ludescher, B., Hirscher, M.

{Journal of Alloys and Compounds}, 352, pages: 57-59, 2003 (article)

mms

[BibTex]

[BibTex]


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Experiment with a crystal-assisted positron source using 6 and 10 GeV electrons

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

{Nuclear Instruments and Methods in Physics Research B}, 201, pages: 243-252, 2003 (article)

mms

[BibTex]

[BibTex]


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Surface patterning of SrTiO3 by 30 keV ion irradiation

Albrecht, J., Leonhardt, S., Spolenak, R., Täffner, U., Habermeier, H. U., Schütz, G.

{Surface Science Letters}, 547, pages: L847-L852, 2003 (article)

mms

[BibTex]

[BibTex]


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Evolution of Fault-tolerant Self-replicating Structures

Righetti, L., Shokur, S., Capcarre, M.

In Advances in Artificial Life, pages: 278-288, Lecture Notes in Computer Science, Springer Berlin Heidelberg, 2003 (inproceedings)

Abstract
Designed and evolved self-replicating structures in cellular automata have been extensively studied in the past as models of Artificial Life. However, CAs, unlike their biological counterpart, are very brittle: any faulty cell usually leads to the complete destruction of any emerging structures, let alone self-replicating structures. A way to design fault-tolerant structures based on error-correcting-code has been presented recently [1], but it required a cumbersome work to be put into practice. In this paper, we get back to the original inspiration for these works, nature, and propose a way to evolve self-replicating structures, faults here being only an idiosyncracy of the environment.

mg

link (url) DOI [BibTex]

link (url) DOI [BibTex]


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Learning from demonstration and adaptation of biped locomotion with dynamical movement primitives

Nakanishi, J., Morimoto, J., Endo, G., Schaal, S., Kawato, M.

In Workshop on Robot Learning by Demonstration, IEEE International Conference on Intelligent Robots and Systems (IROS 2003), Las Vegas, NV, Oct. 27-31, 2003, clmc (inproceedings)

Abstract
In this paper, we report on our research for learning biped locomotion from human demonstration. Our ultimate goal is to establish a design principle of a controller in order to achieve natural human-like locomotion. We suggest dynamical movement primitives as a CPG of a biped robot, an approach we have previously proposed for learning and encoding complex human movements. Demonstrated trajectories are learned through the movement primitives by locally weighted regression, and the frequency of the learned trajectories is adjusted automatically by a novel frequency adaptation algorithm based on phase resetting and entrainment of oscillators. Numerical simulations demonstrate the effectiveness of the proposed locomotion controller.

am

link (url) [BibTex]

link (url) [BibTex]


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Movement planning and imitation by shaping nonlinear attractors

Schaal, S.

In Proceedings of the 12th Yale Workshop on Adaptive and Learning Systems, Yale University, New Haven, CT, 2003, clmc (inproceedings)

Abstract
Given the continuous stream of movements that biological systems exhibit in their daily activities, an account for such versatility and creativity has to assume that movement sequences consist of segments, executed either in sequence or with partial or complete overlap. Therefore, a fundamental question that has pervaded research in motor control both in artificial and biological systems revolves around identifying movement primitives (a.k.a. units of actions, basis behaviors, motor schemas, etc.). What are the fundamental building blocks that are strung together, adapted to, and created for ever new behaviors? This paper summarizes results that led to the hypothesis of Dynamic Movement Primitives (DMP). DMPs are units of action that are formalized as stable nonlinear attractor systems. They are useful for autonomous robotics as they are highly flexible in creating complex rhythmic (e.g., locomotion) and discrete (e.g., a tennis swing) behaviors that can quickly be adapted to the inevitable perturbations of a dy-namically changing, stochastic environment. Moreover, DMPs provide a formal framework that also lends itself to investigations in computational neuroscience. A recent finding that allows creating DMPs with the help of well-understood statistical learning methods has elevated DMPs from a more heuristic to a principled modeling approach, and, moreover, created a new foundation for imitation learning. Theoretical insights, evaluations on a humanoid robot, and behavioral and brain imaging data will serve to outline the framework of DMPs for a general approach to motor control and imitation in robotics and biology.

am

link (url) [BibTex]

link (url) [BibTex]


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Computational approaches to motor learning by imitation

Schaal, S., Ijspeert, A., Billard, A.

Philosophical Transaction of the Royal Society of London: Series B, Biological Sciences, 358(1431):537-547, 2003, clmc (article)

Abstract
Movement imitation requires a complex set of mechanisms that map an observed movement of a teacher onto one's own movement apparatus. Relevant problems include movement recognition, pose estimation, pose tracking, body correspondence, coordinate transformation from external to egocentric space, matching of observed against previously learned movement, resolution of redundant degrees-of-freedom that are unconstrained by the observation, suitable movement representations for imitation, modularization of motor control, etc. All of these topics by themselves are active research problems in computational and neurobiological sciences, such that their combination into a complete imitation system remains a daunting undertaking - indeed, one could argue that we need to understand the complete perception-action loop. As a strategy to untangle the complexity of imitation, this paper will examine imitation purely from a computational point of view, i.e. we will review statistical and mathematical approaches that have been suggested for tackling parts of the imitation problem, and discuss their merits, disadvantages and underlying principles. Given the focus on action recognition of other contributions in this special issue, this paper will primarily emphasize the motor side of imitation, assuming that a perceptual system has already identified important features of a demonstrated movement and created their corresponding spatial information. Based on the formalization of motor control in terms of control policies and their associated performance criteria, useful taxonomies of imitation learning can be generated that clarify different approaches and future research directions.

am

link (url) [BibTex]

link (url) [BibTex]


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Efficient charge recovery method for driving piezoelectric actuators with quasi-square waves

Campolo, D., Sitti, M., Fearing, R. S.

IEEE transactions on ultrasonics, ferroelectrics, and frequency control, 50(3):237-244, IEEE, 2003 (article)

pi

[BibTex]

[BibTex]


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Synthetic gecko foot-hair micro/nano-structures for future wall-climbing robots

Sitti, M., Fearing, R. S.

In Robotics and Automation, 2003. Proceedings. ICRA’03. IEEE International Conference on, 1, pages: 1164-1170, 2003 (inproceedings)

pi

[BibTex]

[BibTex]


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Magnetization reversal study of CoCrPt alloy thin films on a nanogranular-length scale using magnetic transmission soft x-ray microscopy

Im, M. Y., Fischer, P., Eimüller, T., Denbeaux, G., Shin, S. C.

{Applied Physics Letters}, 83(22):4589-4591, 2003 (article)

mms

[BibTex]

[BibTex]


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XANES und MEXAFS an magnetischen Übergangsmetalloxiden: Entwicklung eines digitalen Lock-In XMCD Experimentes mit Phasenschieber

Weigand, F.

Bayerische Julius-Maximilians-Universität Würzburg, Würzburg, 2003 (phdthesis)

mms

[BibTex]

[BibTex]


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Temperature-dependent pinning of vortices in low-angle grain boundaries in YBa2Cu3O7-δ

Albrecht, J.

{Physical Review B}, 68, 2003 (article)

mms

[BibTex]


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Magnetic soft X-ray transmission microscopy

Fischer, P.

{Current Opinion in Solid State \& Materials Science}, 7(2):173-179, 2003 (article)

mms

[BibTex]

[BibTex]


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The magnetic transmission X-ray microscopy project at BESSY II

Eimüller, T., Niemann, B., Guttmann, P., Fischer, P., Englisch, U., Vatter, R., Wolter, C., Seiffert, S., Schmahl, G., Schütz, G.

{Journal de Physique IV}, 104, pages: 91-94, 2003 (article)

mms

[BibTex]

[BibTex]


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Ab-initio statistical mechanics for ordered compounds: single-defect theory vs. cluster-expansion techniques

Drautz, R., Schultz, I., Lechermann, F., Fähnle, M.

{Physica Status Solidi B}, 240(1):37-44, 2003 (article)

mms

[BibTex]

[BibTex]


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Magnetic imaging with soft x-ray microscopies

Fischer, P., Denbeaux, G., Stoll, H., Puzic, A., Raabe, J., Nolting, F., Eimüller, T., Schütz, G.

{Journal de Physique IV}, 104, pages: 471-476, 2003 (article)

mms

[BibTex]

[BibTex]


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Hydrogen storage in carbon nanotubes

Hirscher, M., Becher, M.

{Journal of Nanoscience and Nanotechnology}, 3(1/2):3-17, 2003 (article)

mms

[BibTex]

[BibTex]


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Grain boundary faceting phase transition and thermal grooving in Cu

Straumal, B. B., Polyakov, S. A., Bischoff, E., Mittemeijer, E. J., Gust, W.

In Proceedings of the International Conference on Diffusion, Segregation and Stresses in Materials, 216/217, pages: 93-100, Diffusion and Defect Data, Pt. A, Defect and Diffusion Forum, Scitec Publ., Moscow, 2003 (inproceedings)

mms

[BibTex]

[BibTex]


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AMOC in positron and positronium chemistry

Stoll, H., Castellaz, P., Siegle, A.

In Principles and Applications of Positron and Positronium Chemistry, pages: 344-366, World Scientific Publishers, Singapore, 2003 (incollection)

mms

[BibTex]

[BibTex]


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Strong influence on the electronic structure of Pt adatoms and clusters on graphite

Fauth, K., He\ssler, M., Batchelor, D., Schütz, G.

{Surface Science}, 529(3):397-402, 2003 (article)

mms

[BibTex]

[BibTex]


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NMR studies of hydrogen diffusion in the dihydrides of hafnium

Gottwald, J., Majer, G., Peterson, D. T., Barnes, R. G.

{Journal of Alloys and Compounds}, 356-357, pages: 274-278, 2003 (article)

mms

[BibTex]

[BibTex]


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The +/-45 degrees correlation interferometer as a means to measure phase noise of parametric origin

Rubiola, E., Giordano, V., Stoll, H.

{IEEE Transactions on Instrumentation and Measurement}, 52, pages: 182-188, 2003 (article)

mms

[BibTex]

[BibTex]


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Piezoelectrically actuated four-bar mechanism with two flexible links for micromechanical flying insect thorax

Sitti, M.

IEEE/ASME transactions on mechatronics, 8(1):26-36, IEEE, 2003 (article)

pi

[BibTex]


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Biomimetic propulsion for a swimming surgical micro-robot

Edd, J., Payen, S., Rubinsky, B., Stoller, M. L., Sitti, M.

In Intelligent Robots and Systems, 2003.(IROS 2003). Proceedings. 2003 IEEE/RSJ International Conference on, 3, pages: 2583-2588, 2003 (inproceedings)

pi

Project Page [BibTex]

Project Page [BibTex]


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Slow removal of vacancies in B2-Ni52Al48 upon long-term low-temperature annealing

Zhang, X. Y., Sprengel, W., Reichle, K. J., Blaurock, K., Henes, R., Schaefer, H. E.

{Physical Review B}, 68(22), 2003 (article)

mms

[BibTex]

[BibTex]


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Magnetic domain structure in SmCo 2 : 17 permanent magnets

Zhang, Y., Tang, W., Hadjipanayis, G. C., Chen, C. H., Goll, D., Kronmüller, H.

{IEEE Transactions on Magnetics}, 39(5):2905-2907, 2003 (article)

mms

[BibTex]

[BibTex]


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Energy loss and charge state dependency of swift Nq+ ions scattered off a Pt(110)(1 x 2) surface

Robin, A., Hatke, N., Jensen, J., Plachke, D., Carstanjen, H. D., Heiland, W.

{Nuclear Instruments \& Methods in Physics Research B-Beam Interactions with Materials and Atoms}, 209, pages: 259-264, 2003 (article)

mms

[BibTex]

[BibTex]


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Preparation and properties of [NdFeBx/Nbz]n multi-layer films

Tsai, J. L., Chin, T. S., Yao, Y. D., Melsheimer, A., Fischer, S. F., Dragon, T., Kelsch, M., Kronmüller, H.

{Physica B-Condensed Matter}, 327(2-4):283-286, 2003 (article)

mms

[BibTex]

[BibTex]


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Multilayered magnetic nanostrips studied by transmission X-ray microscopy

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

{Journal de Physique IV}, 104, pages: 483-486, 2003 (article)

mms

[BibTex]

[BibTex]


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Imaging magnetic domain structures with soft X-ray microscopy

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

{Structural Chemistry}, 14(1):39-47, 2003 (article)

mms

[BibTex]

[BibTex]


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Hydrogen solubility and diffusivity in amorphous La14Ni86 films

Cuevas, F., Hirscher, M.

{Acta Materialia}, 51, pages: 701-712, 2003 (article)

mms

[BibTex]

[BibTex]


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Coercivity mechanism in nanocrystalline and bonded magnets

Goll, D., Kronmüller, H.

In Bonded Magnets. Proceedings of the NATO Advanced Research Workshop on Science and Technology of Bonded Magnets, 118, pages: 115-127, NATO Science Series: Series 2, Mathematics, Physics and Chemistry, Kluwer Acad. Publ., Newark, USA, 2003 (inproceedings)

mms

[BibTex]

[BibTex]


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Hydrogen interaction with carbon nanostructures - current situation and future prospects

Orimo, S., Züttel, A., Schlapbach, L., Majer, G., Fukunaga, T., Fujii, H.

{Journal of Alloys and Compounds}, 356-357, pages: 716-719, 2003 (article)

mms

[BibTex]

[BibTex]


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Desorption of hydrogen from blowing agents used for foaming metals

von Zeppelin, F., Hirscher, M., Stanzick, H., Banhart, J.

{Composites Science and Technology}, 63, pages: 2293-2300, 2003 (article)

mms

[BibTex]

[BibTex]


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Investigation of Electromigration in Copper Interconnects by Noise Measurements

Emelianov, V., Ganesan, G., Puzic, A., Schulz, S., Eizenberg, M., Habermeier, H., Stoll, H.

In Noise as a Tool for Studying Materials, pages: 271-281, Proceedings of SPIE, Santa Fe, New Mexico, 2003 (inproceedings)

mms

[BibTex]

[BibTex]


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Entropic wetting of a colloidal rod-sphere mixture

Roth, R., Brader, J. M., Schmidt, M.

{Europhysics Letters}, 63(4):549-555, 2003 (article)

mms

[BibTex]

[BibTex]

2000


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Reciprocal excitation between biological and robotic research

Schaal, S., Sternad, D., Dean, W., Kotoska, S., Osu, R., Kawato, M.

In Sensor Fusion and Decentralized Control in Robotic Systems III, Proceedings of SPIE, 4196, pages: 30-40, Boston, MA, Nov.5-8, 2000, November 2000, clmc (inproceedings)

Abstract
While biological principles have inspired researchers in computational and engineering research for a long time, there is still rather limited knowledge flow back from computational to biological domains. This paper presents examples of our work where research on anthropomorphic robots lead us to new insights into explaining biological movement phenomena, starting from behavioral studies up to brain imaging studies. Our research over the past years has focused on principles of trajectory formation with nonlinear dynamical systems, on learning internal models for nonlinear control, and on advanced topics like imitation learning. The formal and empirical analyses of the kinematics and dynamics of movements systems and the tasks that they need to perform lead us to suggest principles of motor control that later on we found surprisingly related to human behavior and even brain activity.

am

link (url) [BibTex]

2000


link (url) [BibTex]


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Advances in Large Margin Classifiers

Smola, A., Bartlett, P., Schölkopf, B., Schuurmans, D.

pages: 422, Neural Information Processing, MIT Press, Cambridge, MA, USA, October 2000 (book)

Abstract
The concept of large margins is a unifying principle for the analysis of many different approaches to the classification of data from examples, including boosting, mathematical programming, neural networks, and support vector machines. The fact that it is the margin, or confidence level, of a classification--that is, a scale parameter--rather than a raw training error that matters has become a key tool for dealing with classifiers. This book shows how this idea applies to both the theoretical analysis and the design of algorithms. The book provides an overview of recent developments in large margin classifiers, examines connections with other methods (e.g., Bayesian inference), and identifies strengths and weaknesses of the method, as well as directions for future research. Among the contributors are Manfred Opper, Vladimir Vapnik, and Grace Wahba.

ei

Web [BibTex]

Web [BibTex]


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Nonlinear dynamical systems as movement primitives

Schaal, S., Kotosaka, S., Sternad, D.

In Humanoids2000, First IEEE-RAS International Conference on Humanoid Robots, CD-Proceedings, Cambridge, MA, September 2000, clmc (inproceedings)

Abstract
This paper explores the idea to create complex human-like movements from movement primitives based on nonlinear attractor dynamics. Each degree-of-freedom of a limb is assumed to have two independent abilities to create movement, one through a discrete dynamic system, and one through a rhythmic system. The discrete system creates point-to-point movements based on internal or external target specifications. The rhythmic system can add an additional oscillatory movement relative to the current position of the discrete system. In the present study, we develop appropriate dynamic systems that can realize the above model, motivate the particular choice of the systems from a biological and engineering point of view, and present simulation results of the performance of such movement primitives. The model was implemented for a drumming task on a humanoid robot

am

link (url) [BibTex]

link (url) [BibTex]


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Real Time Learning in Humanoids: A challenge for scalability of Online Algorithms

Vijayakumar, S., Schaal, S.

In Humanoids2000, First IEEE-RAS International Conference on Humanoid Robots, CD-Proceedings, Cambridge, MA, September 2000, clmc (inproceedings)

Abstract
While recent research in neural networks and statistical learning has focused mostly on learning from finite data sets without stringent constraints on computational efficiency, there is an increasing number of learning problems that require real-time performance from an essentially infinite stream of incrementally arriving data. This paper demonstrates how even high-dimensional learning problems of this kind can successfully be dealt with by techniques from nonparametric regression and locally weighted learning. As an example, we describe the application of one of the most advanced of such algorithms, Locally Weighted Projection Regression (LWPR), to the on-line learning of the inverse dynamics model of an actual seven degree-of-freedom anthropomorphic robot arm. LWPR's linear computational complexity in the number of input dimensions, its inherent mechanisms of local dimensionality reduction, and its sound learning rule based on incremental stochastic leave-one-out cross validation allows -- to our knowledge for the first time -- implementing inverse dynamics learning for such a complex robot with real-time performance. In our sample task, the robot acquires the local inverse dynamics model needed to trace a figure-8 in only 60 seconds of training.

am

link (url) [BibTex]

link (url) [BibTex]


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Synchronized robot drumming by neural oscillator

Kotosaka, S., Schaal, S.

In The International Symposium on Adaptive Motion of Animals and Machines, Montreal, Canada, August 2000, clmc (inproceedings)

Abstract
Sensory-motor integration is one of the key issues in robotics. In this paper, we propose an approach to rhythmic arm movement control that is synchronized with an external signal based on exploiting a simple neural oscillator network. Trajectory generation by the neural oscillator is a biologically inspired method that can allow us to generate a smooth and continuous trajectory. The parameter tuning of the oscillators is used to generate a synchronized movement with wide intervals. We adopted the method for the drumming task as an example task. By using this method, the robot can realize synchronized drumming with wide drumming intervals in real time. The paper also shows the experimental results of drumming by a humanoid robot.

am

link (url) [BibTex]

link (url) [BibTex]


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An Introduction to Kernel-Based Learning Algorithms

Müller, K., Mika, S., Rätsch, G., Tsuda, K., Schölkopf, B.

In Handbook of Neural Network Signal Processing, 4, (Editors: Yu Hen Hu and Jang-Neng Hwang), CRC Press, 2000 (inbook)

ei

[BibTex]

[BibTex]


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Choosing nu in support vector regression with different noise models — theory and experiments

Chalimourda, A., Schölkopf, B., Smola, A.

In Proceedings of the IEEE-INNS-ENNS International Joint Conference on Neural Networks, IJCNN 2000, Neural Computing: New Challenges and Perspectives for the New Millennium, IEEE, International Joint Conference on Neural Networks, 2000 (inproceedings)

ei

[BibTex]

[BibTex]


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Phenomenological damping in optical response tensors

Buckingham, A., Fischer, P.

PHYSICAL REVIEW A, 61(3), 2000 (article)

Abstract
Although perturbation theory applied to the optical response of a molecule or material system is only strictly valid far from resonances, it is often applied to ``near-resonance{''} conditions by means of complex energies incorporating damping. Inconsistent signs of the damping in optical response tensors have appeared in the recent literature, as have errors in the treatment of the perturbation by a static held. The ``equal-sign{''} convention used in a recent publication yields an unphysical material response, and Koroteev's intimation that linear electro-optical circular dichroism may exist in an optically active liquid under resonance conditions is also flawed. We show that the isotropic part of the Pockels tensor vanishes.

pf

DOI [BibTex]

DOI [BibTex]