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2000


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Dynamics of a bouncing ball in human performance

Sternad, D., Duarte, M., Katsumata, H., Schaal, S.

Physical Review E, 63(011902):1-8, 2000, clmc (article)

Abstract
On the basis of a modified bouncing-ball model, we investigated whether human movements utilize principles of dynamic stability in their performance of a similar movement task. Stability analyses of the model provided predictions about conditions indicative of a dynamically stable period-one regime. In a series of experiments, human subjects bounced a ball rhythmically on a racket and displayed these conditions supporting that they attuned to and exploited the dynamic stability properties of the task.

am

link (url) [BibTex]

2000


link (url) [BibTex]


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Macro to Nano Tele-Manipulation Towards Nanoelectromec hanical Systems

Sitti, M., Hashimoto, H.

Journal of Robotics and Mechatronics, 12(3):209-217, FUJI TECHNOLOGY PRESS LTD., 2000 (article)

pi

[BibTex]

[BibTex]


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Influcence of vortex-vortex interaction on critical currents across low-angle grain boundaries in YBa2Cu3O7-δ

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

{Physical Review B}, 63, 2000 (article)

mms

[BibTex]

[BibTex]


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Symmetrical Tilt Grain boundaries in body-centred cubic transition metals: An ab-initio local-density-functional study

Ochs, T., Beck, O., Elsässer, C., Meyer, B.

{Philosophical Magazine A}, 80, pages: 351-372, 2000 (article)

mms

[BibTex]

[BibTex]


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The liquid ferromagnet Co80Pd20 and its critical exponent γ

Bührer, C., Beckmann, M., Fähnle, M., Maier, K.

{Journal of Magnetism and Magnetic Materials}, 212, pages: 211-224, 2000 (article)

mms

[BibTex]

[BibTex]


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Irreversible magnetization processes in a soft magnetic platelet

Hertel, R., Kronmüller, H.

{Physica B}, 275, pages: 1-4, 2000 (article)

mms

[BibTex]

[BibTex]


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Measurement of the Zener relaxation in high-purity FeCr single crystals

Hirscher, M., Brossmann, U., Henes, R.

{Materials Transactions, JIM}, 41, pages: 82-86, 2000 (article)

mms

[BibTex]

[BibTex]


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Ab-initio statistical mechanics for alloy phase diagrams and ordering phenomena including the effect of vacancies

Lechermann, F., Fähnle, M.

{Physical Review B}, 63, 2000 (article)

mms

[BibTex]


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Reactions in TiO2/Ti3Al and TiO2/TiAl bilayers: Application of target-factor analysis in auger electron spectroscopy

van Lier, J., Baretzky, B., Zalar, A., Mittemeijer, E. J.

{Surface and Interface Analysis}, 30, pages: 124-129, 2000 (article)

mms

[BibTex]

[BibTex]


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Ab-initio treatment of noncollinear spin systems within the atomic-sphere approximation and beyond

Grotheer, O., Ederer, C., Fähnle, M.

{Physical Review B}, 62, pages: 5601-5608, 2000 (article)

mms

[BibTex]

[BibTex]


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Is d-Al-Cu-Co a random tiling?

Zeger, G., Plachke, D., Carstanjen, H. D., Trebin, H. R.

{Materials Science and Engineering A}, 294, pages: 291-294, 2000 (article)

mms

[BibTex]

[BibTex]


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Nonlinear magnetoelastic coupling coefficients in Fe from an ab-initio calculation

Komelj, M., Fähnle, M.

{Journal of Magnetism and Magnetic Materials}, 220, pages: L 7-L 12, 2000 (article)

mms

[BibTex]

[BibTex]


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Current densities in low-angle grain boundaries of YBCO

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

{Physica C}, 341-348, pages: 1459-1460, 2000 (article)

mms

[BibTex]

[BibTex]


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The hydrogen desorption kinetics of Pd-coated LaNi5-type films

Cuevas, F., Hirscher, M.

{Journal of Alloys and Compounds}, 313, pages: 269-275, 2000 (article)

mms

[BibTex]

[BibTex]


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The structure of the trihydride GdH3

Ellner, M., Reule, H., Mittemeijer, E. J.

{Journal of Alloys and Compounds}, 309, pages: 127-131, 2000 (article)

mms

[BibTex]

[BibTex]


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Corrosion resistance of the vacuum arc deposited Ti, TiN and TiO2 coatings on large area glass substrates

Vershinin, N., Filonov, K., Straumal, B., Gust, W., Dimitriou, R., Kovalev, A., Camacho, J.

{Surface and Coatings Technology}, 125, pages: 223-228, 2000 (article)

mms

[BibTex]

[BibTex]


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Is the insulator-metal transition in perovskites associated with the bulk magnetic phase transition?

Baszynski, J., Walz, F., Tolinski, T.

{Sensors and Actuators}, 81, pages: 37-39, 2000 (article)

mms

[BibTex]

[BibTex]


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Correlated molecular-field theory of amorphous ferromagnets and the Gibbs free energy

Fähnle, M.

{Journal of Magnetism and Magnetic Materials}, 210, pages: L 1-L 4, 2000 (article)

mms

[BibTex]

[BibTex]


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Pinning mechanism of vortices at antiphase boundaries in YBa2Cu3O7-δ

Jooss, C., Warthmann, R., Kronmüller, H.

{Physical Review B}, 61, pages: 12433-12446, 2000 (article)

mms

[BibTex]

[BibTex]


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Spectral distribution of activation energies in YBa2Cu3O7-δthin films

Warthmann, R., Albrecht, J., Kronmüller, H., Joos, C.

{Physical Review B}, 62, pages: 15226-15229, 2000 (article)

mms

[BibTex]

[BibTex]


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Ab-initio calculation of the formation and migration energies for Monovacancies in Mg

Krimmel, H., Fähnle, M.

{Physical Review B}, 62, pages: 5489-5491, 2000 (article)

mms

[BibTex]

[BibTex]


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Controlled pushing of nanoparticles: modeling and experiments

Sitti, M., Hashimoto, H.

IEEE/ASME transactions on mechatronics, 5(2):199-211, IEEE, 2000 (article)

pi

[BibTex]

[BibTex]


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Investigation of strain softening of icosahedral AlPdMn single quasicrystals

Brunner, D., Plachke, D., Carstanjen, H. D.

{Physica Status Solidi (A)}, 177, pages: 203-217, 2000 (article)

mms

[BibTex]

[BibTex]


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Formation and evolution of the transverse anisotropy with nanocrystallization in amorphous Fe73.5CuNb3Si13.5B9 ribbons

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

{Physical Review}, 62, pages: 5760-5764, 2000 (article)

mms

[BibTex]

[BibTex]


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Deflection of 32.8 TeV/c fully stripped Pb ions by means of a bent Si crystal

Biino, C., Clement, M., Doble, N., Elsener, K., Gatignon, L., Grafström, P., Herr, W., Keppler, P., Major, J., Mikkelsen, U., Taratin, A., Velasco, M.

{Nuclear Instruments and Methods in Physics Research B}, 160, pages: 536-543, 2000 (article)

mms

[BibTex]

[BibTex]


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Replacing muons by protons: polarized beam NMR

Schüth, J., Eversheim, P.-D., Herzog, P., Maier, K., Majer, G., Meyer, P., Roduner, E.

{Physica B}, 289-290, pages: 672-675, 2000 (article)

mms

[BibTex]

[BibTex]


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Charge transport mechanisms in single crystalline yttrium iron garnet as resolved by magnetic relaxation

Walz, F., Torres, L., Iñiguez, J., Kronmüller, H.

{Physica Status Solidi (A)}, 180, pages: 507-522, 2000 (article)

mms

[BibTex]

[BibTex]


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Theory of self-diffusion in alkali metals I. Results for monovacancies in Li, Na, and K

Schott, V., Fähnle, M., Madden, P. A.

{Journal of Physics: Condensed Matter}, 12, pages: 1171-1194, 2000 (article)

mms

[BibTex]

[BibTex]


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Theory of self-diffusion in alkali metals II. The influence of divacancies in Li

Schott, V., Fähnle, M., Madden, P. A.

{Journal of Physics: Condensed Matter}, 12, pages: 1195-1198, 2000 (article)

mms

[BibTex]

[BibTex]


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Decay kinetics of nonequilibrium Al-Si solid solutions

Sluchanko, N. E., Glushkov, V. V., Demishev, S. V., Kondrin, M. V., Ischenko, T. V., Gust, W., Brazhkin, V. V., Straumal, B. B., Bruynseraede, Y., Moshchalkov, V. V.

{Physical Review B}, 61, pages: 6019-6027, 2000 (article)

mms

[BibTex]

[BibTex]


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Vacuum arc deposition of Ti coatings

Straumal, B., Gust, W., Vershinin, N., Dimitriou, R., Rabkin, E.

{Surface and Coatings Technology}, 125, pages: 157-160, 2000 (article)

mms

[BibTex]

[BibTex]


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Internal friction in Ni-rich B2-NiAl

Brossmann, U., Hirscher, M., Schaible, D., Kronmüller, H.

{Scripta Materialia}, 42, pages: 1193-1197, 2000 (article)

mms

[BibTex]

[BibTex]


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Spectral distribution of activation energies in YBa2Cu3O7-δthin films

Warthmann, R., Albrecht, J., Kronmüller, H., Joos, C.

{Physical Review B}, 62, pages: 15226-15229, 2000 (article)

mms

[BibTex]

[BibTex]


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Pre-treatment of large area strips with the aid of a high power hall current accelerator

Vershinin, N., Dimitriou, R., Benmalek, M., Straumal, B., Gust, W., Vivas, J., Shulga, J.

{Surface and Coatings Technology}, 125, pages: 35-39, 2000 (article)

mms

[BibTex]

[BibTex]

1999


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< 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]


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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]


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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]


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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]


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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]


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Teleoperated nano scale object manipulation

Sitti, M., Hashimoto, H.

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

pi

[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)

pi

[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]