Header logo is


2004


no image
Grain boundary wetting by a solid phase; microstructural development in a Zn-5 wt\textpercent Al alloy

Lopez, G. A., Mittemeijer, E. J., Straumal, B. B.

{Acta Materialia}, 52(15):4537-4545, 2004 (article)

mms

[BibTex]

2004


[BibTex]


no image
Electronic correlations, magnetism, and structure of Fe-Al subsystems: An LDA+U study

Lechermann, F., Fähnle, M., Meyer, B., Elsässer, C.

{Physical Review B}, 69, 2004 (article)

mms

[BibTex]

[BibTex]


no image
Interaction of hydrogen isotopes with carbon nanostructures

Haluska, M., Hirscher, M., Becher, M., Dettlaff-Weglikowska, U., Chen, X., Roth, S.

{Materials Science and Engineering B}, 108, pages: 130-133, 2004 (article)

mms

[BibTex]

[BibTex]


no image
Formation of nanograined structure and decomposition of supersaturated solid solution during high pressure torsion of Al-Zn and Al-Mg alloys

Straumal, B. B., Baretzky, B., Mazilkin, A. A., Phillipp, F., Kogtenkova, O. A., Volkov, M. N., Valiev, R. Z.

{Acta Materialia}, 52, pages: 4469-4478, 2004 (article)

mms

[BibTex]

[BibTex]


no image
Ab-initio modeling of nonlinear magnetoelastic coupling in epitaxial films

Komelj, M., Fähnle, M.

{Journal of Magnetism and Magnetic Materials}, 272-276, pages: e1587-e1588, 2004 (article)

mms

[BibTex]

[BibTex]


no image
Atomic force microscope probe based controlled pushing for nanotribological characterization

Sitti, M.

IEEE/ASME Transactions on mechatronics, 9(2):343-349, IEEE, 2004 (article)

pi

[BibTex]

[BibTex]


no image
Effective exchange interaction in a quasi-two-dimensional self-assembled nanoparticle array

Wiedwald, U., Cerchez, M., Farle, M., Fauth, K., Schütz, G., Zürn, K., Boyen, H., Ziemann, P.

{Physical Review B}, 70, 2004 (article)

mms

DOI [BibTex]

DOI [BibTex]


no image
How well does total electron yield measure x-ray absorption in nanoparticles?

Fauth, K.

{Applied Physics Letters}, 85(15):3271-3273, 2004 (article)

mms

DOI [BibTex]

DOI [BibTex]


no image
Ordering and magnetism in Fe-Co: Dense sequence of ground-state structures

Drautz, R., Diaz-Ortiz, A., Fähnle, M., Dosch, H.

{Physical Review Letters}, 93(6), 2004 (article)

mms

[BibTex]

[BibTex]


no image
Thermal reversal of elongated ferromagnetic particles misoriented to the applied field

Goll, D., Bertram, H. N.

{IEEE Transactions on Magnetics}, 40(4):2416-2418, 2004 (article)

mms

[BibTex]

[BibTex]


no image
Anisotropy of the orbital moments and the magnetic dipole term Tz in CrO2: An ab-initio study

Komelj, M., Ederer, C., Fähnle, M.

{Physical Review B}, 69, 2004 (article)

mms

[BibTex]

[BibTex]


no image
Core-shell iron-iron oxide nanoparticles: magnetic properties and interactions

Theil-Kuhn, L., Bojesen, A., Timmermann, L., Fauth, K., Goering, E. J., Johnson, E., Meedom Nielsen, M., Morup, S.

{Journal of Magnetism and Magnetic Materials}, 272-276, pages: 1485-1486, 2004 (article)

mms

[BibTex]

[BibTex]


no image
Measurement of very low bulk concentrations (below 1 atppm) of hydrogen using ERDA

Tripathi, A., Kruse, O., Carstanjen, H. D.

{Nuclear Instruments and Methods B}, 219-220, pages: 435-439, 2004 (article)

mms

[BibTex]

[BibTex]


no image
Unusual doublet structure in proton magnetic-resonance spectra of yttrium and lutetium trihydrides

Majer, G., Telfah, A., Grinberg, F., Barnes, R. G.

{Physical Review B}, 70(13), 2004 (article)

mms

[BibTex]

[BibTex]


no image
Kinetics of primary nanocrystallization in Al-rich metallic glass with quenched-in nuclei

Wang, J. Q., Zhang, H. W., Gu, X. J., Lu, K., Sommer, F., Mittemeijer, E.

{Materials Science and Engineering A}, 375-377, pages: 980-984, 2004 (article)

mms

[BibTex]

[BibTex]


no image
3-dimensional Wulff diagrams for \Sigma3 grain boundaries in Cu

Straumal, B., Kucherinenko, Y., Baretzky, B.

{Reviews on Advanced Materials Science}, 7(1):23-31, 2004 (article)

mms

[BibTex]

[BibTex]


no image
First-principles study of the interplay between magnetism and phase equilibria in Fe-Co systems

Diaz-Ortiz, A., Drautz, R., Fähnle, M., Dosch, H.

{Journal of Magnetism and Magnetic Materials}, 272-276, pages: 780-782, 2004 (article)

mms

[BibTex]

[BibTex]


no image
Magnetic field optimization of permanent magnet unulators for arbitrary polarization

Bahrdt, J., Frentrup, W., Gaupp, A., Scheer, M., Englisch, U.

{Nuclear Instruments and Methods in Physics Research A}, 516, pages: 575-585, 2004 (article)

mms

[BibTex]

[BibTex]


no image
High-resolution imaging of fast magnetization dynamics in magnetic nanostructures

Stoll, H., Puzic, A., Van Waeyenberge, B., Fischer, P., Raabe, J., Buess, M., Haug, T., Höllinger, R., Back, C., Weiss, D., Denbeaux, G.

{Applied Physics Letters}, 84, pages: 3328-3330, 2004 (article)

mms

[BibTex]

[BibTex]


no image
Comparison of low-temperature magnetic relaxations in two systems GdAl2Dx (C15 Laves phase) and Fe3O4 (Inverse spinel)

Walz, F., Reule, H., Hirscher, M., Kronmüller, H.

{Physica Status Solidi B}, 241(2):389-400, 2004 (article)

mms

[BibTex]

[BibTex]


no image
General relations between many-body potentials and cluster expansions in multi-component systems

Drautz, R., Fähnle, M., Sanchez, J.M.

{Journal of Physics: Condensed Matter}, 16, pages: 3843-3852, 2004 (article)

mms

[BibTex]

[BibTex]


no image
Counting individual atom layers in graphite - high-resolution RBS experiments on HOPG (highly ordered pyrolytic graphite)

Srivastava, S. K., Plachke, D., Szökefalvi-Nagy, A., Major, J., Carstanjen, H. D.

{Nuclear Instruments and Methods B}, 219-220, pages: 364-368, 2004 (article)

Abstract
{The paper reports about recent experiments on HOPG (highly oriented pyrolytic graphite) by high-resolution RBS (Rutherford backscattering spectroscopy). By using an ion beam of 1 MeV N+ up to 7 individual monolayers could be identified in the RBS spectrum from such a sample. This is about twice as much as observed by other groups up to now. Since close to the surface the RBS peaks from the individual carbon layers are well separated, various quantities important for the ion-solid interaction can be determined with high precision, such as the stopping power of 1 MeV N ions in graphite and their energy straggling. Close to the surface the RBS peaks are asymmetric which is well explained in the framework of the Landau theory of energy straggling.}

mms

[BibTex]

[BibTex]


no image
Feedback error learning and nonlinear adaptive control

Nakanishi, J., Schaal, S.

Neural Networks, 17(10):1453-1465, 2004, clmc (article)

Abstract
In this paper, we present our theoretical investigations of the technique of feedback error learning (FEL) from the viewpoint of adaptive control. We first discuss the relationship between FEL and nonlinear adaptive control with adaptive feedback linearization, and show that FEL can be interpreted as a form of nonlinear adaptive control. Second, we present a Lyapunov analysis suggesting that the condition of strictly positive realness (SPR) associated with the tracking error dynamics is a sufficient condition for asymptotic stability of the closed-loop dynamics. Specifically, for a class of second order SISO systems, we show that this condition reduces to KD^2 > KP; where KP and KD are positive position and velocity feedback gains, respectively. Moreover, we provide a ÔpassivityÕ-based stability analysis which suggests that SPR of the tracking error dynamics is a necessary and sufficient condition for asymptotic hyperstability. Thus, the condition KD^2>KP mentioned above is not only a sufficient but also necessary condition to guarantee asymptotic hyperstability of FEL, i.e. the tracking error is bounded and asymptotically converges to zero. As a further point, we explore the adaptive control and FEL framework for feedforward control formulations, and derive an additional sufficient condition for asymptotic stability in the sense of Lyapunov. Finally, we present numerical simulations to illustrate the stability properties of FEL obtained from our mathematical analysis.

am

link (url) [BibTex]

link (url) [BibTex]


no image
Micromagnetism and the microstructure of high-temperature permanent magnets

Goll, D., Kronmüller, H., Stadelmaier, H. H.

{Journal of Applied Physics}, 96(11):6534-6545, 2004 (article)

mms

[BibTex]

[BibTex]


no image
Atomic defects and diffusion in intermetallic compounds with DO3 structure: An ab-initio study

Fähnle, M., Schimmele, L.

{Zeitschrift f\"ur Metallkunde}, 95, pages: 864-869, 2004 (article)

mms

[BibTex]

[BibTex]


no image
Cluster surface interactions: Small Fe clusters driven nonmagnetic on graphite

Fauth, K., Gold, S., He\ssler, M., Schütz, G.

{Chemical Physics Letters}, 392(4-6):498-502, 2004 (article)

mms

DOI [BibTex]

DOI [BibTex]


no image
\textquotesingleWetting by solid state’grain boundary phase transition in Zn-Al alloys

Straumal, B. B., Khruzhcheva, A. S., Lopez, G. A.

{Reviews on Advanced Materials Science}, 7(1):13-22, 2004 (article)

mms

[BibTex]

[BibTex]


no image
Two prototypes of metal adatom configurations on Mo(112): an ab initio study for Li and Co

Singer, R., Drautz, R., Fähnle, M.

{Surface Science}, 559, pages: 241-248, 2004 (article)

mms

[BibTex]

[BibTex]


no image
Grain boundary phase transitions and their influence on properties of polycrystals

Straumal, B., Baretzky, B.

{Interface Science}, 12(2-3):147-155, 2004 (article)

mms

[BibTex]

[BibTex]


no image
Swift heavy ion induced modification of Si/C60 multilayers

Srivastava, S. K., Kabiraj, D., Schattat, B., Carstanjen, H. D., Avasthi, D. K.

{Nuclear Instruments and Methods in Physics Research B}, 219 - 220, pages: 815-819, 2004 (article)

mms

[BibTex]

[BibTex]


no image
Static displacements of Pd in the solid solution PdBy (0\textlessy\textless0.2) as determined by neutron diffraction

Berger, T. G., Leineweber, A., Mittemeijer, E. J., Fischer, P.

{Physica Status Solidi (A)}, 201, pages: 1484-1492, 2004 (article)

mms

[BibTex]

[BibTex]


no image
X-MCD magnetometry of CMR perovskites La0.67-yREyCa0.33MnO3

Sikora, M., Kapusta, C., Zajac, D., Tokarz, W., Oates, C. J., Borowiec, M., Rybicki, D., Goering, E. J., Fischer, P., Schütz, G., De Teresa, J. M., Ibarra, M. R.

{Journal of Magnetism and Magnetic Materials}, 272-276, pages: 2148-2150, 2004 (article)

mms

[BibTex]

[BibTex]


no image
Critical thicknesses of domain formations in cubic particles and thin films

Kronmüller, H., Goll, D., Hertel, R., Schütz, G.

{Physica B}, 343(1-4):229-235, 2004 (article)

mms

[BibTex]

[BibTex]

1999


no image
< 研究速報>(< 小特集> マイクロマシン)

Sitti, M., 橋本秀紀,

生産研究, 51(8):651-653, 東京大学, 1999 (article)

pi

[BibTex]

1999


[BibTex]


no image
Micro/Nano Manipulation Using Atomic Force Microscope.

Sitti, M., Hashimoto, H.

生産研究, 51(8):651-653, 東京大学生産技術研究所, 1999 (article)

pi

[BibTex]

[BibTex]


no image
Is imitation learning the route to humanoid robots?

Schaal, S.

Trends in Cognitive Sciences, 3(6):233-242, 1999, clmc (article)

Abstract
This review will focus on two recent developments in artificial intelligence and neural computation: learning from imitation and the development of humanoid robots. It will be postulated that the study of imitation learning offers a promising route to gain new insights into mechanisms of perceptual motor control that could ultimately lead to the creation of autonomous humanoid robots. This hope is justified because imitation learning channels research efforts towards three important issues: efficient motor learning, the connection between action and perception, and modular motor control in form of movement primitives. In order to make these points, first, a brief review of imitation learning will be given from the view of psychology and neuroscience. In these fields, representations and functional connections between action and perception have been explored that contribute to the understanding of motor acts of other beings. The recent discovery that some areas in the primate brain are active during both movement perception and execution provided a first idea of the possible neural basis of imitation. Secondly, computational approaches to imitation learning will be described, initially from the perspective of traditional AI and robotics, and then with a focus on neural network models and statistical learning research. Parallels and differences between biological and computational approaches to imitation will be highlighted. The review will end with an overview of current projects that actually employ imitation learning for humanoid robots.

am

link (url) [BibTex]

link (url) [BibTex]


no image
Virtual Reality-Based Teleoperation in the Micro/Nano World.

Sitti, M., Hashimoto, H.

生産研究, 51(8):654-656, 東京大学生産技術研究所, 1999 (article)

pi

[BibTex]

[BibTex]


no image
Segmentation of endpoint trajectories does not imply segmented control

Sternad, D., Schaal, D.

Experimental Brain Research, 124(1):118-136, 1999, clmc (article)

Abstract
While it is generally assumed that complex movements consist of a sequence of simpler units, the quest to define these units of action, or movement primitives, still remains an open question. In this context, two hypotheses of movement segmentation of endpoint trajectories in 3D human drawing movements are re-examined: (1) the stroke-based segmentation hypothesis based on the results that the proportionality coefficient of the 2/3 power law changes discontinuously with each new â??strokeâ?, and (2) the segmentation hypothesis inferred from the observation of piecewise planar endpoint trajectories of 3D drawing movements. In two experiments human subjects performed a set of elliptical and figure-8 patterns of different sizes and orientations using their whole arm in 3D. The kinematic characteristics of the endpoint trajectories and the seven joint angles of the arm were analyzed. While the endpoint trajectories produced similar segmentation features as reported in the literature, analyses of the joint angles show no obvious segmentation but rather continuous oscillatory patterns. By approximating the joint angle data of human subjects with sinusoidal trajectories, and by implementing this model on a 7-degree-of-freedom anthropomorphic robot arm, it is shown that such a continuous movement strategy can produce exactly the same features as observed by the above segmentation hypotheses. The origin of this apparent segmentation of endpoint trajectories is traced back to the nonlinear transformations of the forward kinematics of human arms. The presented results demonstrate that principles of discrete movement generation may not be reconciled with those of rhythmic movement as easily as has been previously suggested, while the generalization of nonlinear pattern generators to arm movements can offer an interesting alternative to approach the question of units of action.

am

link (url) [BibTex]

link (url) [BibTex]


no image
Teleoperated nano scale object manipulation

Sitti, M., Hashimoto, H.

Recent Advances on Mechatronics, pages: 322-335, Singapore: Springer-Verlag, 1999 (article)

pi

[BibTex]

[BibTex]

1996


no image
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]


no image
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]