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2001


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Magnetic viscosity and demagnetization behaviour in isotropic nanocrystalline Pr12Fe82B6 ribbons

Zhang, H. W., Zhang, S. Y., Shen, B. G., Goll, D., Kronmüller, H.

{Chinese Physics}, 10(12):1169-1171, 2001 (article)

mms

[BibTex]

2001


[BibTex]


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Strain relaxation and internal friction in the range of the glass transition

Ege, M., Ulfert, W., Kronmüller, H.

{Zeitschrift f\"ur Metallkunde}, 92(7):690-694, 2001 (article)

mms

[BibTex]

[BibTex]


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Hardness-depth profiling on nanometer scale

Kunert, M., Baretzky, B., Baker, S. P., Mittemeijer, E. J.

{Metallurgical and Materials Transactions A-Physical Metallurgy and Materials Science}, 32(5):1201-1209, 2001 (article)

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[BibTex]

[BibTex]


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Compound formation and abrasion resistance of ion-implanted Ti6Al4V

Schmidt, H., Schminke, A., Schmiedgen, M., Baretzky, B.

{Acta Materialia}, 49(3):487-495, 2001 (article)

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[BibTex]

[BibTex]


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Influence of vortex-vortex interaction on critical currents across low-angle grain boundaries in YBa2Cu3O7-δthin films

Albrecht, J., Leonhardt, S., Kronmüller, H.

{Physical Review B}, 63, 2001 (article)

mms

[BibTex]

[BibTex]


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Structure of superconducting [BaCuOx]2/[CaCuO2]n superlattices on SrTiO3(001) investigated by x-ray scattering

Aruta, C., Zegenhagen, J., Cowie, B., Balestrino, G., Pasquini, G., Medaglia, P. G., Ricci, F., Luebbert, D., Baumbach, T., Riedo, E., Ortega, L., Kremer, R., Albrecht, J.

{Physica Status Solidi (A)}, 183, pages: 353-364, 2001 (article)

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[BibTex]

[BibTex]


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Transmission X-ray microscopy using X-MCD

Eimüller, T., Fischer, P., Köhler, M., Scholz, M., Guttmann, P., Denbeaux, G., Glück, S., Bayreuther, G., Schmahl, G., Attwood, D., Schütz, G.

{Applied Physics A}, 73, pages: 697-701, 2001 (article)

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[BibTex]

[BibTex]


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Soft X-ray microscopy to 25 nm with applications to biology and magnetic materials

Denbeaux, G., Anderson, E., Chao, W., Eimüller, T., Johnson, L., Köhler, M., Larabell, C., Legros, M., Fischer, P., Pearson, A., Schütz, G., Yager, D., Attwood, D.

{Nuclear Instruments and Methods in Physics Research A}, 467-468, pages: 841-844, 2001 (article)

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[BibTex]

[BibTex]


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Study of in-plane magnetic domains with magnetic transmission X-ray microscopy

Fischer, P., Eimüller, T., Schütz, G., Köhler, M., Bayreuther, G., Denbeaux, G., Attwood, D.

{Journal of Applied Physics}, 89, pages: 7159-7161, 2001 (article)

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[BibTex]

[BibTex]


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Influence of vortex-vortex interaction on critical currents across low-angle grain boundaries in YBa2Cu3O7-δthin films

Albrecht, J., Leonhardt, S., Kronmüller, H.

{Physical Review B}, 63, 2001 (article)

mms

[BibTex]

[BibTex]


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Non-symmetric influences in the total electron yield X-ray magnetic circular dichroism signal in applied magnetic fields

Goering, E., Gold, S., Bayer, A., Schütz, G.

{Journal of Synchrotron Radiation}, 8, pages: 434-436, 2001 (article)

mms

DOI [BibTex]

DOI [BibTex]


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Effect of Ga substitution on the magnetocrystalline anisotropy of arc-melted Sm2Co17-xGax (x\textequals5,6) compounds

Liang, B., Kleinschroth, I., Kronmüller, H.

{Journal of Applied Physics}, 89(1):488-491, 2001 (article)

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[BibTex]

[BibTex]


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Biomimetic oculomotor control

Shibata, T., Vijayakumar, S., Conradt, J., Schaal, S.

Adaptive Behavior, 9(3/4):189-207, 2001, clmc (article)

Abstract
Oculomotor control in a humanoid robot faces similar problems as biological oculomotor systems, i.e., capturing targets accurately on a very narrow fovea, dealing with large delays in the control system, the stabilization of gaze in face of unknown perturbations of the body, selective attention, and the complexity of stereo vision. In this paper, we suggest control circuits to realize three of the most basic oculomotor behaviors and their integration - the vestibulo-ocular and optokinetic reflex (VOR-OKR) for gaze stabilization, smooth pursuit for tracking moving objects, and saccades for overt visual attention. Each of these behaviors and the mechanism for their integration was derived with inspiration from computational theories as well as behavioral and physiological data in neuroscience. Our implementations on a humanoid robot demonstrate good performance of the oculomotor behaviors, which proves to be a viable strategy to explore novel control mechanisms for humanoid robotics. Conversely, insights gained from our models have been able to directly influence views and provide new directions for computational neuroscience research.

am

link (url) [BibTex]

link (url) [BibTex]


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Irradiation-induced electron tunnelling and small-polaron hopping in single-crystalline YIG

Walz, F., Brabers, J. H. V. J., Torres, L., Kronmüller, H.

{Physica Status Solidi B-Basic Research}, 228(3):717-730, 2001 (article)

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[BibTex]

[BibTex]


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Hexagonally ordered 100 nm period nickel nanowire arrays

Nielsch, K., Wehrspohn, R. B., Barthel, J., Kirschner, J., Gösele, U., Fischer, S. F., Kronmüller, H.

{Applied Physics Letters}, 79(9):1360-1362, 2001 (article)

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[BibTex]

[BibTex]


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Magnetization processes in isotropic and textured Nd2Fe14B- films

Melsheimer, A., Kronmüller, H.

{Physica B}, 299(3-4):251-259, 2001 (article)

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[BibTex]

[BibTex]


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Critical magnetic properties of disordered Cr-rich FeCr alloys

Fischer, S. F., Kaul, S. N., Kronmüller, H.

{Journal of Magnetism and Magnetic Materials}, 226(Sp. Iss. SI):540-541, 2001 (article)

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[BibTex]

[BibTex]


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Fast ab initio methods for the calculation of adiabatic spin wave spectra in complex systems

Grotheer, O., Ederer, C., Fähnle, M.

{Physical Review B}, 63(10):100401-100401, 2001 (article)

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[BibTex]

[BibTex]


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Hydrogen storage in sonicated carbon materials

Hirscher, M., Becher, M., Haluska, M., Dettlaff-Weglikowska, U., Quintel, A., Duesberg, G. S., Choi, Y. M., Downes, P., Hulman, M., Roth, S., Stepanek, I., Bernier, P.

{Applied Physics A-Materials Science \& Processing}, 72(2):129-132, 2001 (article)

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[BibTex]

[BibTex]


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Co(NH3)2Cl2 and Co(ND3)2Cl2: Order-Disorder Behaviour of N(H,D)3 and Antiferromagnetic Structure

Leineweber, A., Jacobs, H., E\ssmann, P., Allenspach, F., Fauth, F., Fischer, P.

{Zeitschrift f\"ur Anorganische und Allgemeine Chemie}, 627, pages: 2063-2069, 2001 (article)

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[BibTex]

[BibTex]


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Critical magnetic properties of disordered polycrystalline Fe75Fe25 and Cr70Fe30 alloys

Fischer, S. F., Kaul, S. N., Kronmüller, H.

{Physical Review B}, 65, 2001 (article)

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[BibTex]

[BibTex]


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Diffusion of 23Na and 35K in the eutectic melt Na0.32K0.69

Feinauer, A., Majer, G.

{Physical Review B}, 64, 2001 (article)

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[BibTex]

[BibTex]


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Influence of nanocrystallization on the evolution of domain patterns and the magnetoimpedance effect in amorphous Fe73.5Cu1Nb3Si13.5B9 ribbons

Guo, H. Q., Kronmüller, H., Dragon, T., Cheng, Z. H., Shen, B. G.

{Journal of Applied Physics}, 89(1):514-520, 2001 (article)

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[BibTex]

[BibTex]


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Ab-initio statistical mechanics for the phase diagram of NiAl including the effect of vacancies

Lechermann, F., Fähnle, M.

{Physica Status Solidi (B)}, 224, pages: R4-R6, 2001 (article)

mms

[BibTex]

[BibTex]

1996


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A Kendama learning robot based on bi-directional theory

Miyamoto, H., Schaal, S., Gandolfo, F., Koike, Y., Osu, R., Nakano, E., Wada, Y., Kawato, M.

Neural Networks, 9(8):1281-1302, 1996, clmc (article)

Abstract
A general theory of movement-pattern perception based on bi-directional theory for sensory-motor integration can be used for motion capture and learning by watching in robotics. We demonstrate our methods using the game of Kendama, executed by the SARCOS Dextrous Slave Arm, which has a very similar kinematic structure to the human arm. Three ingredients have to be integrated for the successful execution of this task. The ingredients are (1) to extract via-points from a human movement trajectory using a forward-inverse relaxation model, (2) to treat via-points as a control variable while reconstructing the desired trajectory from all the via-points, and (3) to modify the via-points for successful execution. In order to test the validity of the via-point representation, we utilized a numerical model of the SARCOS arm, and examined the behavior of the system under several conditions.

am

link (url) [BibTex]

1996


link (url) [BibTex]


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One-handed juggling: A dynamical approach to a rhythmic movement task

Schaal, S., Sternad, D., Atkeson, C. G.

Journal of Motor Behavior, 28(2):165-183, 1996, clmc (article)

Abstract
The skill of rhythmic juggling a ball on a racket is investigated from the viewpoint of nonlinear dynamics. The difference equations that model the dynamical system are analyzed by means of local and non-local stability analyses. These analyses yield that the task dynamics offer an economical juggling pattern which is stable even for open-loop actuator motion. For this pattern, two types of pre dictions are extracted: (i) Stable periodic bouncing is sufficiently characterized by a negative acceleration of the racket at the moment of impact with the ball; (ii) A nonlinear scaling relation maps different juggling trajectories onto one topologically equivalent dynamical system. The relevance of these results for the human control of action was evaluated in an experiment where subjects performed a comparable task of juggling a ball on a paddle. Task manipulations involved different juggling heights and gravity conditions of the ball. The predictions were confirmed: (i) For stable rhythmic performance the paddle's acceleration at impact is negative and fluctuations of the impact acceleration follow predictions from global stability analysis; (ii) For each subject, the realizations of juggling for the different experimental conditions are related by the scaling relation. These results allow the conclusion that for the given task, humans reliably exploit the stable solutions inherent to the dynamics of the task and do not overrule these dynamics by other control mechanisms. The dynamical scaling serves as an efficient principle to generate different movement realizations from only a few parameter changes and is discussed as a dynamical formalization of the principle of motor equivalence.

am

link (url) [BibTex]

link (url) [BibTex]

1995


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Memory-based neural networks for robot learning

Atkeson, C. G., Schaal, S.

Neurocomputing, 9, pages: 1-27, 1995, clmc (article)

Abstract
This paper explores a memory-based approach to robot learning, using memory-based neural networks to learn models of the task to be performed. Steinbuch and Taylor presented neural network designs to explicitly store training data and do nearest neighbor lookup in the early 1960s. In this paper their nearest neighbor network is augmented with a local model network, which fits a local model to a set of nearest neighbors. This network design is equivalent to a statistical approach known as locally weighted regression, in which a local model is formed to answer each query, using a weighted regression in which nearby points (similar experiences) are weighted more than distant points (less relevant experiences). We illustrate this approach by describing how it has been used to enable a robot to learn a difficult juggling task. Keywords: memory-based, robot learning, locally weighted regression, nearest neighbor, local models.

am

link (url) [BibTex]

1995


link (url) [BibTex]