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2005


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First-principles investigation of the Ni-Fe-Al system

Lechermann, F., Fähnle, M., Sanchez, J. M.

{Intermetallics}, 13((10)):1096-1109, 2005 (article)

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[BibTex]

2005


[BibTex]


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GdN thin films: Bulk and local electronic and magnetic properties

Leuenberger, F., Parge, A., Felsch, W., Fauth, K., He\ssler, M.

{Physical Review B}, 72(1), 2005 (article)

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[BibTex]

[BibTex]


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Hydrogen permeation through Pd/Fe and Pd/Ni multilayer systems

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

{Journal of Alloys and Compounds}, 393(1-2):5-10, 2005 (article)

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[BibTex]

[BibTex]


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Parametrization of the magnetic energy at the atomic level

Drautz, R., Fähnle, M.

{Physical Review B}, 72, 2005 (article)

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[BibTex]

[BibTex]


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Time-scales of electronic processes in Fe3O4 - An attempt to resolve a recently accentuated controversy

Fähnle, M., Kronmüller, H., Walz, F.

{Physica B}, 369, pages: 177-180, 2005 (article)

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[BibTex]


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Interlayer contraction in MgB2 upon replacement of Mg by Al: Effect of the covalent bond energy

Bester, G., Fähnle, M.

{Physical Review B}, 72, 2005 (article)

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[BibTex]

[BibTex]


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First-principles atomistic modeling of ordering phenomena and phase diagrams

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

{TMS Letters}, 2(1):7-8, 2005 (article)

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[BibTex]

[BibTex]


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Constrained spin-density functional theory for excited magnetic configurations in an adiabatic approximation

Singer, R., Fähnle, M., Bihlmayer, G.

{Physical Review B}, 71, 2005 (article)

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[BibTex]

[BibTex]


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The influence of magnetism on atomic defects and diffusion: model calculations and ab initio electron theory

Fähnle, M., Schimmele, L.

{Defect and Diffusion Forum}, 237-240, pages: 19-29, 2005 (article)

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[BibTex]

[BibTex]


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X-ray magnetic circular dichroism sum rule correction for the light transition metals

Goering, E.

{Philosophical Magazine}, 85, pages: 2895-2911, 2005 (article)

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[BibTex]

[BibTex]


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Temperature dependence of the magnetocrystalline anisotropy energy and projected microscopic magnetic moments in epitaxial CrO2 films

Gold, S., Goering, E., König, C., Rüdiger, U., Güntherodt, G., Schütz, G.

{Physical Review B}, 71(22), 2005 (article)

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On the imaging of the flux-line lattice of a type-II superconductor by soft X-ray absorption spectroscopy

Fähnle, M., Albrecht, J., Eimüller, T., Fisher, P., Goering, E., Steiauf, D., Schütz, G.

{Journal of Synchrotron Radiation}, 12, pages: 251-253, 2005 (article)

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[BibTex]

[BibTex]


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Grain-boundary melting phase transition in the Cu-Bi system

Divinski, S., Lohmann, M., Herzig, C., Straumal, B., Baretzky, B., Gust, W.

{Physical Review B}, 71, 2005 (article)

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[BibTex]

[BibTex]


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A fast ab initio approach to the simulation of spin dynamics

Fähnle, M., Drautz, R., Singer, R., Steiauf, D., Berkov, D. V.

{Computational Materials Science}, 32, pages: 118-122, 2005 (article)

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[BibTex]


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Hydrogen adsorption in different carbon nanostructures

Panella, B., Hirscher, M., Roth, S.

{Carbon}, 43, pages: 2209-2214, 2005 (article)

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[BibTex]

[BibTex]


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Synthesis of the nanocrystalline MgS and its interaction with hydrogen

Goo, N. H., Hirscher, M.

{Journal of Alloys and Compounds}, 404, pages: 503-506, 2005 (article)

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[BibTex]

[BibTex]


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Time-scales of electronic processes in Fe3O4 - An attempt to resolve a recently accentuated controversy

Fähnle, M., Kronmüller, H., Walz, F.

{Physica B}, 369, pages: 177-180, 2005 (article)

mms

[BibTex]

[BibTex]


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Bending of magnetic avalanches in MgB2 thin films

Albrecht, J., Matveev, A., Djupmyr, M., Schütz, G., Stuhlhofer, B., Habermeier, H.

{Applied Physics Letters}, 87, 2005 (article)

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[BibTex]

[BibTex]


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Magnetic pinning of flux lines in heterostructures of cuprates and manganites

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

{Physical Review B}, 72, 2005 (article)

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[BibTex]


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On the pair-potential modelling of alloy surfaces

Drautz, R., Fähnle, M.

{Surface Science}, 585, pages: 108-112, 2005 (article)

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[BibTex]


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Crystal field parameters at the (0001) surface of rare-earth metals: an ab initio study

Welsch, F., Fähnle, M., Jensen, P. J.

{Journal of Physics: Condensed Matter}, 17, pages: 2061-2072, 2005 (article)

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[BibTex]


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Spatially resolved ferromagnetic resonance: Imaging of ferromagnetic eigenmodes

Puzic, A., Van Waeyenberge, B., Chou, K. W., Fischer, P., Stoll, H., Schütz, G., Tyliszczak, T., Rott, K., Brückl, H., Reiss, G., Neudecker, I., Haug, T., Buess, M., Back, C. H.

{Journal of Applied Physics}, 97, 2005 (article)

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DOI [BibTex]

DOI [BibTex]


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Proton magnetic resonance spectra of YH3 and LuH3

Brady, S. K., Conradi, M. S., Majer, G., Barnes, R. G.

{Physical Review B}, 72, 2005 (article)

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[BibTex]

[BibTex]


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Hydrogen storage in spherical nanoporous carbons

Terres, E., Panella, B., Hayashi, T., Kim, Y. A., Endo, M., Dominguez, J. M., Hirscher, M., Terrones, H., Terrones, H.

{Chemical Physics Letters}, 403(4-6):363-366, 2005 (article)

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Faceting and migration of twin grain boundaries in zinc

Straumal, B. B., Rabkin, E., Sursaeva, V. G., Goruakova, A. S.

{Zeitschrift f\"ur Metallkunde}, 96(2):161-166, 2005 (article)

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Nanostructures with high surface area for hydrogen storage

Hirscher, M., Panella, B.

{Journal of Alloys and Compounds}, 404, pages: 399-401, 2005 (article)

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[BibTex]

[BibTex]


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Timescale settling and nature of electron transport in magnetite - General considerations in view of new magnetic after-effect results on dilutely Ti4+-doped Fe3O4

Walz, F., Brabers, V. A. M., Brabers, J. H. V. J., Kronmüller, H.

{Journal of Physics: Condensed Matter}, 17(42):6763-6781, 2005 (article)

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[BibTex]

[BibTex]


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Topological k-space refinement of the configurational energy of alloys

Shchyglo, O., Bugaev, V. N., Drautz, R., Udyansky, A., Reichert, H., Dosch, H.

{Physical Review B}, 72(14), 2005 (article)

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[BibTex]


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Large surface area nanostructures for hydrogen storage

Hirscher, M., Panella, B.

{Annales de Chimie}, 30(5):519-529, 2005 (article)

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[BibTex]

[BibTex]


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Electronic and magnetic properties of ligand-free FePt nanoparticles

Boyen, H., Fauth, K., Stahl, B., Ziemann, P., Kästle, G., Weigl, F., Banhart, F., He\ssler, M., Schütz, G., Gajbhiye, N. S., Ellrich, J., Hahn, H., Büttner, M., Garnier, M. G., Oelhafen, P.

{Advanced Materials}, 17(5):574-578, 2005 (article)

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DOI [BibTex]

DOI [BibTex]


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Identification of extrinsic Mn contributions in Ga1-xMnxAs by field-dependent magnetic circular X-ray dichroism

Rader, O., Fauth, K., Gould, C., Rüster, C., Schott, G. M., Schmidt, G., Brunner, K., Molenkamp, L. W., Schütz, G., Kronast, F., Dürr, H. A., Eberhardt, W., Gudat, W.

{Journal of Electron Spectroscopy and Related Phenomena}, 144(Sp. issue):789-792, 2005 (article)

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DOI [BibTex]

DOI [BibTex]


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Fundamentals of interface phenomena in advanced bulk nanoscale materials

Baretzky, B., Baró, M. D., Grabovetskaya, G. P., Gubicza, J., Ivanov, M. B., Kolobov, Y. R., Langdon, T. G., Lendvai, J., Lipnitskii, A. G., Mazilkin, A. A., Nazarov, A. A., Nogués, J., Ovidko, I. A., Protasova, S. G., Raab, G. I., Révész, Á., Skiba, N. V., Sort, J., Starink, M. J., Straumal, B. B., Suriñach, S., Ungár, T., Zhilyaev, A. P.

{Reviews on Advanced Materials Science}, 9(1):45-108, 2005 (article)

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Formation of nanostructure during high-pressure torsion of Al-Zn, Al-Mg and Al-Zn-Mg alloys

Mazilkin, A. A., Kogtenkova, O. A., Straumal, B. B., Ruslan, Z, Valiev, Z., Baretzky, B.

{Defect and Diffusion Forum}, 237-240, pages: 739-744, 2005 (article)

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[BibTex]

[BibTex]


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Micromagnetic simulation as a bridge between magnetic-force and magnetic-transmission X-ray microscopy

Bolte, M., Eiselt, R., Eimüller, T.

{Journal of Magnetism and Magnetic Materials}, 290, pages: 723-726, 2005 (article)

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[BibTex]

[BibTex]


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Grain-boundary melting phase transition in the Cu-Bi system

Divinski, S., Lohmann, M., Herzig, C., Straumal, B., Baretzky, B., Gust, W.

{Physical Review B}, 71, 2005 (article)

mms

[BibTex]

[BibTex]

1998


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SVMs — a practical consequence of learning theory

Schölkopf, B.

IEEE Intelligent Systems and their Applications, 13(4):18-21, July 1998 (article)

Abstract
My first exposure to Support Vector Machines came this spring when heard Sue Dumais present impressive results on text categorization using this analysis technique. This issue's collection of essays should help familiarize our readers with this interesting new racehorse in the Machine Learning stable. Bernhard Scholkopf, in an introductory overview, points out that a particular advantage of SVMs over other learning algorithms is that it can be analyzed theoretically using concepts from computational learning theory, and at the same time can achieve good performance when applied to real problems. Examples of these real-world applications are provided by Sue Dumais, who describes the aforementioned text-categorization problem, yielding the best results to date on the Reuters collection, and Edgar Osuna, who presents strong results on application to face detection. Our fourth author, John Platt, gives us a practical guide and a new technique for implementing the algorithm efficiently.

ei

PDF Web DOI [BibTex]

1998


PDF Web DOI [BibTex]


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Learning view graphs for robot navigation

Franz, M., Schölkopf, B., Mallot, H., Bülthoff, H.

Autonomous Robots, 5(1):111-125, March 1998 (article)

Abstract
We present a purely vision-based scheme for learning a topological representation of an open environment. The system represents selected places by local views of the surrounding scene, and finds traversable paths between them. The set of recorded views and their connections are combined into a graph model of the environment. To navigate between views connected in the graph, we employ a homing strategy inspired by findings of insect ethology. In robot experiments, we demonstrate that complex visual exploration and navigation tasks can thus be performed without using metric information.

ei

PDF PDF DOI [BibTex]

PDF PDF DOI [BibTex]


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Surface second-order nonlinear optical activity

Fischer, P., Buckingham, A.

JOURNAL OF THE OPTICAL SOCIETY OF AMERICA B-OPTICAL PHYSICS, 15(12):2951-2957, 1998 (article)

Abstract
Following the recent observation of a large second-harmonic intensity difference from a monolayer of chiral molecules with left and right circularly polarized light, the scattering theory is generalized and extended to predict linear and circular intensity differences for the more Versatile sum-frequency spectroscopy. Estimates indicate that intensity differences should be detectable for a typical experimental arrangement. The second-order nonlinear surface susceptibility tensor is given for different surface point groups in the electric dipole approximation; it is shown that nonlinear optical activity phenomena unambiguously probe molecular chirality only for molecular monolayers that are symmetric about the normal. Other surface symmetries can give rise to intensity differences from monolayers composed of achiral molecules. A water surface is predicted to show Linear and nonlinear optical activity in the presence of an electric field parallel to the surface. (C) 1998 Optical Society of America {[}S0740-3224(98)01311-3] OCIS codes: 190.0190, 190.4350, 240.6490.

pf

DOI [BibTex]

DOI [BibTex]


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Linear electro-optic effect in optically active liquids

Buckingham, A., Fischer, P.

CHEMICAL PHYSICS LETTERS, 297(3-4):239-246, 1998 (article)

Abstract
A linear effect of an electrostatic field F on the intensity of sum- and difference-frequency generation in a chiral liquid is predicted. It arises in the electric dipole approximation. The effect changes sign with the enantiomer and on reversing the direction of the electrostatic field. The sum-frequency generator chi(alpha beta gamma)((2)) (-omega(3);omega(1),omega(2)), where omega(3) = omega(1) + omega(2), and the electric field-induced sum-frequency generator chi(alpha beta gamma delta)((3))(-omega(3);omega(1),omega(2),0)F-delta interfere and their contributions to the scattering power can be distinguished. Encouraging predictions are given for a typical experimental arrangement. (C) 1998 Elsevier Science B.V. All rights reserved.

pf

DOI [BibTex]

DOI [BibTex]


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Monolayers of hexadecyltrimethylammonium p-tosylate at the air-water interface. 1. Sum-frequency spectroscopy

Bell, G., Li, Z., Bain, C., Fischer, P., Duffy, D.

JOURNAL OF PHYSICAL CHEMISTRY B, 102(47):9461-9472, 1998 (article)

Abstract
Sum-frequency vibrational spectroscopy has been used to determine the structure of monolayers of the cationic surfactant, hexadecyltrimethylammonium p-tosylate (C(16)TA(+)Ts(-)), at the surface of water. Selective deuteration of the cation or the anion allowed the separate detection of sum-frequency spectra of the surfactant and of counterions that are bound to the monolayer. The p-tosylate ions an oriented with their methyl groups pointing away from the aqueous subphase and with the C-2 axis tilted, on average, by 30-40 degrees from the surface normal. The vibrational spectra of C(16)TA(+) indicate that the number of gauche defects in the monolayer does not change dramatically when bromide counterions are replaced by p-tosylate. The ends of the hydrocarbon chains of C16TA+ are, however, tilted much further from the surface normal in the presence of p-tosylate than in the presence of bromide. A quantitative analysis of the sum-frequency spectra requires a knowledge of the molecular hyperpolarizability tensor: the role of ab initio calculations and Raman spectroscopy in determining the components of this tensor is discussed.

pf

DOI [BibTex]

DOI [BibTex]


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Ultraviolet resonance Raman study of drug binding in dihydrofolate reductase, gyrase, and catechol O-methyltransferase

Couling, V., Fischer, P., Klenerman, D., Huber, W.

BIOPHYSICAL JOURNAL, 75(2):1097-1106, 1998 (article)

Abstract
This paper presents a study of the use of ultraviolet resonance Raman (UVRR) spectroscopic methods as a means of elucidating aspects of drug-protein interactions. Some of the RR vibrational bands of the aromatic amino acids tyrosine and tryptophan are sensitive to the microenvironment, and the use of UV excitation radiation allows selective enhancement of the spectral features of the aromatic amino acids, enabling observation specifically of their change in microenvironment upon drug binding. The three drug-protein systems investigated in this study are dihydrofolate reductase with its inhibitor trimethoprim, gyrase with novobiocin, and catechol O-methyltransferase with dinitrocatechol. It is demonstrated that UVRR spectroscopy has adequate sensitivity to be a useful means of detecting drug-protein interactions in those systems for which the electronic absorption of the aromatic amino acids changes because of hydrogen bonding and/or possible dipole-dipole and dipole-polarizability interactions with the ligand.

pf

DOI [BibTex]

DOI [BibTex]


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Tele-nanorobotics using an atomic force microscope as a nanorobot and sensor

Sitti, M., Hashimoto, H.

Advanced Robotics, 13(4):417-436, Taylor & Francis, 1998 (article)

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[BibTex]

[BibTex]


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Constructive incremental learning from only local information

Schaal, S., Atkeson, C. G.

Neural Computation, 10(8):2047-2084, 1998, clmc (article)

Abstract
We introduce a constructive, incremental learning system for regression problems that models data by means of spatially localized linear models. In contrast to other approaches, the size and shape of the receptive field of each locally linear model as well as the parameters of the locally linear model itself are learned independently, i.e., without the need for competition or any other kind of communication. Independent learning is accomplished by incrementally minimizing a weighted local cross validation error. As a result, we obtain a learning system that can allocate resources as needed while dealing with the bias-variance dilemma in a principled way. The spatial localization of the linear models increases robustness towards negative interference. Our learning system can be interpreted as a nonparametric adaptive bandwidth smoother, as a mixture of experts where the experts are trained in isolation, and as a learning system which profits from combining independent expert knowledge on the same problem. This paper illustrates the potential learning capabilities of purely local learning and offers an interesting and powerful approach to learning with receptive fields. 

am

link (url) [BibTex]

link (url) [BibTex]


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Local adaptive subspace regression

Vijayakumar, S., Schaal, S.

Neural Processing Letters, 7(3):139-149, 1998, clmc (article)

Abstract
Incremental learning of sensorimotor transformations in high dimensional spaces is one of the basic prerequisites for the success of autonomous robot devices as well as biological movement systems. So far, due to sparsity of data in high dimensional spaces, learning in such settings requires a significant amount of prior knowledge about the learning task, usually provided by a human expert. In this paper we suggest a partial revision of the view. Based on empirical studies, we observed that, despite being globally high dimensional and sparse, data distributions from physical movement systems are locally low dimensional and dense. Under this assumption, we derive a learning algorithm, Locally Adaptive Subspace Regression, that exploits this property by combining a dynamically growing local dimensionality reduction technique  as a preprocessing step with a nonparametric learning technique, locally weighted regression, that also learns the region of validity of the regression. The usefulness of the algorithm and the validity of its assumptions are illustrated for a synthetic data set, and for data of the inverse dynamics of human arm movements and an actual 7 degree-of-freedom anthropomorphic robot arm. 

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]

1993


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

Schaal, S., Ehrlenspiel, K.

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

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

am

[BibTex]

1993


[BibTex]