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2004


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Nanoscale Materials for Energy Storage
{Materials Science \& Engineering B}, 108, pages: 292, Elsevier, 2004 (misc)

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[BibTex]

2004


[BibTex]


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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]


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Learning from demonstration and adaptation of biped locomotion

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

Robotics and Autonomous Systems, 47(2-3):79-91, 2004, clmc (article)

Abstract
In this paper, we introduce a framework for learning biped locomotion using dynamical movement primitives based on non-linear oscillators. 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 central pattern generator (CPG) of a biped robot, an approach we have previously proposed for learning and encoding complex human movements. Demonstrated trajectories are learned through movement primitives by locally weighted regression, and the frequency of the learned trajectories is adjusted automatically by a novel frequency adaptation algorithmbased on phase resetting and entrainment of coupled oscillators. Numerical simulations and experimental implementation on a physical robot demonstrate the effectiveness of the proposed locomotioncontroller.

am

link (url) [BibTex]

link (url) [BibTex]


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Critical sizes for ferromagnetic spherical hollow nanoparticles

Goll, D., Berkowitz, A. E., Bertram, H. N.

{Physical Review B}, 70(18), 2004 (article)

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[BibTex]

[BibTex]


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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)

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[BibTex]

[BibTex]


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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)

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[BibTex]

[BibTex]


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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)

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[BibTex]

[BibTex]


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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)

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[BibTex]

[BibTex]


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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)

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[BibTex]

[BibTex]


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Atomic force microscope probe based controlled pushing for nanotribological characterization

Sitti, M.

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

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[BibTex]

[BibTex]


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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)

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DOI [BibTex]

DOI [BibTex]


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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]


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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)

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[BibTex]

[BibTex]


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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]


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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]


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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)

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[BibTex]

[BibTex]


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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]


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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]


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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]


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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]


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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)

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[BibTex]

[BibTex]


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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)

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[BibTex]

[BibTex]


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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]


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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]


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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]


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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.}

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[BibTex]

[BibTex]


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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]


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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]


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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]


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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]


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\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]


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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]


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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]


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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)

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[BibTex]

[BibTex]


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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]


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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]


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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]

2002


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Optimized Support Vector Machines for Nonstationary Signal Classification

Davy, M., Gretton, A., Doucet, A., Rayner, P.

IEEE Signal Processing Letters, 9(12):442-445, December 2002 (article)

Abstract
This letter describes an efficient method to perform nonstationary signal classification. A support vector machine (SVM) algorithm is introduced and its parameters optimised in a principled way. Simulations demonstrate that our low complexity method outperforms state-of-the-art nonstationary signal classification techniques.

ei

PostScript Web DOI [BibTex]

2002


PostScript Web DOI [BibTex]


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A New Discriminative Kernel from Probabilistic Models

Tsuda, K., Kawanabe, M., Rätsch, G., Sonnenburg, S., Müller, K.

Neural Computation, 14(10):2397-2414, October 2002 (article)

ei

PDF [BibTex]

PDF [BibTex]


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Functional Genomics of Osteoarthritis

Aigner, T., Bartnik, E., Zien, A., Zimmer, R.

Pharmacogenomics, 3(5):635-650, September 2002 (article)

ei

Web [BibTex]

Web [BibTex]


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Constructing Boosting algorithms from SVMs: an application to one-class classification.

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

IEEE Transactions on Pattern Analysis and Machine Intelligence, 24(9):1184-1199, September 2002 (article)

Abstract
We show via an equivalence of mathematical programs that a support vector (SV) algorithm can be translated into an equivalent boosting-like algorithm and vice versa. We exemplify this translation procedure for a new algorithm—one-class leveraging—starting from the one-class support vector machine (1-SVM). This is a first step toward unsupervised learning in a boosting framework. Building on so-called barrier methods known from the theory of constrained optimization, it returns a function, written as a convex combination of base hypotheses, that characterizes whether a given test point is likely to have been generated from the distribution underlying the training data. Simulations on one-class classification problems demonstrate the usefulness of our approach.

ei

DOI [BibTex]

DOI [BibTex]


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Forward models in visuomotor control

Mehta, B., Schaal, S.

J Neurophysiol, 88(2):942-53, August 2002, clmc (article)

Abstract
In recent years, an increasing number of research projects investigated whether the central nervous system employs internal models in motor control. While inverse models in the control loop can be identified more readily in both motor behavior and the firing of single neurons, providing direct evidence for the existence of forward models is more complicated. In this paper, we will discuss such an identification of forward models in the context of the visuomotor control of an unstable dynamic system, the balancing of a pole on a finger. Pole balancing imposes stringent constraints on the biological controller, as it needs to cope with the large delays of visual information processing while keeping the pole at an unstable equilibrium. We hypothesize various model-based and non-model-based control schemes of how visuomotor control can be accomplished in this task, including Smith Predictors, predictors with Kalman filters, tapped-delay line control, and delay-uncompensated control. Behavioral experiments with human participants allow exclusion of most of the hypothesized control schemes. In the end, our data support the existence of a forward model in the sensory preprocessing loop of control. As an important part of our research, we will provide a discussion of when and how forward models can be identified and also the possible pitfalls in the search for forward models in control.

am

link (url) [BibTex]

link (url) [BibTex]


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Co-Clustering of Biological Networks and Gene Expression Data

Hanisch, D., Zien, A., Zimmer, R., Lengauer, T.

Bioinformatics, (Suppl 1):145S-154S, 18, July 2002 (article)

Abstract
Motivation: Large scale gene expression data are often analysed by clustering genes based on gene expression data alone, though a priori knowledge in the form of biological networks is available. The use of this additional information promises to improve exploratory analysis considerably. Results: We propose constructing a distance function which combines information from expression data and biological networks. Based on this function, we compute a joint clustering of genes and vertices of the network. This general approach is elaborated for metabolic networks. We define a graph distance function on such networks and combine it with a correlation-based distance function for gene expression measurements. A hierarchical clustering and an associated statistical measure is computed to arrive at a reasonable number of clusters. Our method is validated using expression data of the yeast diauxic shift. The resulting clusters are easily interpretable in terms of the biochemical network and the gene expression data and suggest that our method is able to automatically identify processes that are relevant under the measured conditions.

ei

Web [BibTex]

Web [BibTex]


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Confidence measures for protein fold recognition

Sommer, I., Zien, A., von Ohsen, N., Zimmer, R., Lengauer, T.

Bioinformatics, 18(6):802-812, June 2002 (article)

ei

[BibTex]

[BibTex]


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The contributions of color to recognition memory for natural scenes

Wichmann, F., Sharpe, L., Gegenfurtner, K.

Journal of Experimental Psychology: Learning, Memory and Cognition, 28(3):509-520, May 2002 (article)

Abstract
The authors used a recognition memory paradigm to assess the influence of color information on visual memory for images of natural scenes. Subjects performed 5-10% better for colored than for black-and-white images independent of exposure duration. Experiment 2 indicated little influence of contrast once the images were suprathreshold, and Experiment 3 revealed that performance worsened when images were presented in color and tested in black and white, or vice versa, leading to the conclusion that the surface property color is part of the memory representation. Experiments 4 and 5 exclude the possibility that the superior recognition memory for colored images results solely from attentional factors or saliency. Finally, the recognition memory advantage disappears for falsely colored images of natural scenes: The improvement in recognition memory depends on the color congruence of presented images with learned knowledge about the color gamut found within natural scenes. The results can be accounted for within a multiple memory systems framework.

ei

PDF Web DOI [BibTex]

PDF Web DOI [BibTex]


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Training invariant support vector machines

DeCoste, D., Schölkopf, B.

Machine Learning, 46(1-3):161-190, January 2002 (article)

Abstract
Practical experience has shown that in order to obtain the best possible performance, prior knowledge about invariances of a classification problem at hand ought to be incorporated into the training procedure. We describe and review all known methods for doing so in support vector machines, provide experimental results, and discuss their respective merits. One of the significant new results reported in this work is our recent achievement of the lowest reported test error on the well-known MNIST digit recognition benchmark task, with SVM training times that are also significantly faster than previous SVM methods.

ei

PDF DOI [BibTex]

PDF DOI [BibTex]


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Model Selection for Small Sample Regression

Chapelle, O., Vapnik, V., Bengio, Y.

Machine Learning, 48(1-3):9-23, 2002 (article)

Abstract
Model selection is an important ingredient of many machine learning algorithms, in particular when the sample size in small, in order to strike the right trade-off between overfitting and underfitting. Previous classical results for linear regression are based on an asymptotic analysis. We present a new penalization method for performing model selection for regression that is appropriate even for small samples. Our penalization is based on an accurate estimator of the ratio of the expected training error and the expected generalization error, in terms of the expected eigenvalues of the input covariance matrix.

ei

PostScript [BibTex]

PostScript [BibTex]