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2007


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Separating convolutive mixtures by pairwise mutual information minimization", IEEE Signal Processing Letters

Zhang, K., Chan, L.

IEEE Signal Processing Letters, 14(12):992-995, 2007 (article)

Abstract
Blind separation of convolutive mixtures by minimizing the mutual information between output sequences can avoid the side effect of temporally whitening the outputs, but it involves the score function difference, whose estimation may be problematic when the data dimension is greater than two. This greatly limits the application of this method. Fortunately, for separating convolutive mixtures, pairwise independence of outputs leads to their mutual independence. As an implementation of this idea, we propose a way to separate convolutive mixtures by enforcing pairwise independence. This approach can be applied to separate convolutive mixtures of a moderate number of sources.

ei

Web [BibTex]


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Frequency-domain displacement sensing with a fiber ring-resonator containing a variable gap

Vollmer, F., Fischer, P.

SENSORS AND ACTUATORS A-PHYSICAL, 134(2):410-413, 2007 (article)

Abstract
Ring-resonators are in general not amenable to strain-free (non-contact) displacement measurements. We show that this limitation may be overcome if the ring-resonator, here a fiber-loop, is designed to contain a gap, such that the light traverses a free-space part between two aligned waveguide ends. Displacements are determined with nanometer sensitivity by measuring the associated changes in the resonance frequencies. Miniaturization should increase the sensitivity of the ring-resonator interferometer. Ring geometries that contain an optical circulator can be used to profile reflective samples. (c) 2006 Elsevier B.V. All rights reserved.

pf

DOI [BibTex]

DOI [BibTex]


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Relative Entropy Policy Search

Peters, J.

CLMC Technical Report: TR-CLMC-2007-2, Computational Learning and Motor Control Lab, Los Angeles, CA, 2007, clmc (techreport)

Abstract
This technical report describes a cute idea of how to create new policy search approaches. It directly relates to the Natural Actor-Critic methods but allows the derivation of one shot solutions. Future work may include the application to interesting problems.

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PDF link (url) [BibTex]

PDF link (url) [BibTex]


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Observation of the Faraday effect via beam deflection in a longitudinal magnetic field

Ghosh, A., Hill, W., Fischer, P.

PHYSICAL REVIEW A, 76(5), 2007 (article)

Abstract
We show that magnetic-field-induced circular differential deflection of light can be observed in reflection or refraction at a single interface. The difference in the reflection or refraction angles between the two circular polarization components is a function of the magnetic-field strength and the Verdet constant, and permits the observation of the Faraday effect not via polarization rotation in transmission, but via changes in the propagation direction. Deflection measurements do not suffer from n-pi ambiguities and are shown to be another means to map magnetic fields with high axial resolution, or to determine the sign and magnitude of magnetic-field pulses in a single measurement.

pf

DOI [BibTex]


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Circular differential double diffraction in chiral media

Ghosh, A., Fazal, F. M., Fischer, P.

OPTICS LETTERS, 32(13):1836-1838, 2007 (article)

Abstract
In an optically active liquid the diffraction angle depends on the circular polarization state of the incident light beam. We report the observation of circular differential diffraction in an isotropic chiral medium, and we demonstrate that double diffraction is an alternate means to determine the handedness (enantiomeric excess) of a solution. (c) 2007 Optical Society of America.

pf

DOI [BibTex]

DOI [BibTex]


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Bacterial flagella-based propulsion and on/off motion control of microscale objects

Behkam, B., Sitti, M.

Applied Physics Letters, 90(2):023902, AIP, 2007 (article)

pi

[BibTex]

[BibTex]


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Friction of partially embedded vertically aligned carbon nanofibers inside elastomers

Aksak, B., Sitti, M., Cassell, A., Li, J., Meyyappan, M., Callen, P.

Applied Physics Letters, 91(6):061906, AIP, 2007 (article)

pi

[BibTex]

[BibTex]


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Enhanced friction of elastomer microfiber adhesives with spatulate tips

Kim, S., Aksak, B., Sitti, M.

Applied Physics Letters, 91(22):221913, AIP, 2007 (article)

pi

Project Page [BibTex]

Project Page [BibTex]


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The new robotics - towards human-centered machines

Schaal, S.

HFSP Journal Frontiers of Interdisciplinary Research in the Life Sciences, 1(2):115-126, 2007, clmc (article)

Abstract
Research in robotics has moved away from its primary focus on industrial applications. The New Robotics is a vision that has been developed in past years by our own university and many other national and international research instiutions and addresses how increasingly more human-like robots can live among us and take over tasks where our current society has shortcomings. Elder care, physical therapy, child education, search and rescue, and general assistance in daily life situations are some of the examples that will benefit from the New Robotics in the near future. With these goals in mind, research for the New Robotics has to embrace a broad interdisciplinary approach, ranging from traditional mathematical issues of robotics to novel issues in psychology, neuroscience, and ethics. This paper outlines some of the important research problems that will need to be resolved to make the New Robotics a reality.

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link (url) [BibTex]

link (url) [BibTex]


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On the spatial statistics of optical flow

Roth, S., Black, M. J.

International Journal of Computer Vision, 74(1):33-50, 2007 (article)

Abstract
We present an analysis of the spatial and temporal statistics of "natural" optical flow fields and a novel flow algorithm that exploits their spatial statistics. Training flow fields are constructed using range images of natural scenes and 3D camera motions recovered from hand-held and car-mounted video sequences. A detailed analysis of optical flow statistics in natural scenes is presented and machine learning methods are developed to learn a Markov random field model of optical flow. The prior probability of a flow field is formulated as a Field-of-Experts model that captures the spatial statistics in overlapping patches and is trained using contrastive divergence. This new optical flow prior is compared with previous robust priors and is incorporated into a recent, accurate algorithm for dense optical flow computation. Experiments with natural and synthetic sequences illustrate how the learned optical flow prior quantitatively improves flow accuracy and how it captures the rich spatial structure found in natural scene motion.

ps

pdf preprint pdf from publisher [BibTex]

pdf preprint pdf from publisher [BibTex]


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Hydrogen storage in metal-organic frameworks

Hirscher, M., Panella, B.

{Scripta Materialia}, 56, pages: 809-812, 2007 (article)

mms

[BibTex]

[BibTex]


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Substrate-induced current anisotropy in YBa2Cu3O7-δthin films

Djupmyr, M., Albrecht, J.

{Physica C}, 460-462, pages: 1190-1191, 2007 (article)

mms

DOI [BibTex]

DOI [BibTex]


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A micellar approach to magnetic ultrahigh-density data-storage media: extending the limits of current colloidal methods

Ethirajan, A., Wiedwald, U., Boyen, H.-G., Kern, B., Han, L., Klimmer, A., Weigl, F., Kästle, G., Ziemann, P., Fauth, K., Cai, J., Behm, J., Romanyuk, A., Oelhafen, P., Walther, P., Biskupek, J., Kaiser, U.

{Advanced Materials}, 19, pages: 406-410, 2007 (article)

mms

[BibTex]

[BibTex]


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Size dependence in the magnetization reversal of Fe/Gd multilayers on self-assembled arrays of nanospheres

Amaladass, E., Ludescher, B., Schütz, G., Tyliszczak, T., Eimüller, T.

{Applied Physics Letters}, 91, 2007 (article)

mms

DOI [BibTex]

DOI [BibTex]


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Ma\ssgeschneiderte Wasserstoffspeicher

Hirscher, M., Panella, B.

{Nachrichten aus der Gdch-Energieinitiative}, (Sonderheft April 2007):12-13, 2007 (article)

mms

[BibTex]

[BibTex]


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Reconstruction of historical alloys for pipe organs brings true Baroque music back to life.

Baretzky, B., Friesel, M., Straumal, B.

{MRS Bulletin}, 32, pages: 249-255, 2007 (article)

mms

[BibTex]

[BibTex]


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Analysis of results from X-ray magnetic reflectometry for magnetic multilayer systems

Fähnle, M., Steiauf, D., Martosiswoyo, L., Goering, E., Brück, S., Schütz, G.

{Physical Review B}, 75, 2007 (article)

mms

[BibTex]

[BibTex]


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Dramatic role of critical current anisotropy on flux avalanches in MgB2 films

Albrecht, J., Matveev, A. T., Strempfer, J., Habermeier, H.-U., Shantsev, D. V., Galperin, Y. M., Johansen, T. H.

{Physical Review Letters}, 98, 2007 (article)

mms

[BibTex]

[BibTex]


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Transport properties of LCMO/YBCO hybrid structures

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

{Materials Science and Engineering B}, 144, pages: 15-18, 2007 (article)

mms

DOI [BibTex]

DOI [BibTex]


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Microscale and nanoscale robotics systems [grand challenges of robotics]

Sitti, M.

IEEE Robotics \& Automation Magazine, 14(1):53-60, IEEE, 2007 (article)

pi

[BibTex]

[BibTex]


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A new biomimetic adhesive for therapeutic capsule endoscope applications in the gastrointestinal tract

Glass, P., Sitti, M., Appasamy, R.

Gastrointestinal Endoscopy, 65(5):AB91, Mosby, 2007 (article)

pi

[BibTex]

[BibTex]


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Visual servoing-based autonomous 2-D manipulation of microparticles using a nanoprobe

Onal, C. D., Sitti, M.

IEEE Transactions on control systems technology, 15(5):842-852, IEEE, 2007 (article)

pi

[BibTex]

[BibTex]


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Assistive technology and robotic control using MI ensemble-based neural interface systems in humans with tetraplegia

Donoghue, J. P., Nurmikko, A., Black, M. J., Hochberg, L.

Journal of Physiology, Special Issue on Brain Computer Interfaces, 579, pages: 603-611, 2007 (article)

Abstract
This review describes the rationale, early stage development, and initial human application of neural interface systems (NISs) for humans with paralysis. NISs are emerging medical devices designed to allowpersonswith paralysis to operate assistive technologies or to reanimatemuscles based upon a command signal that is obtained directly fromthe brain. Such systems require the development of sensors to detect brain signals, decoders to transformneural activity signals into a useful command, and an interface for the user.We review initial pilot trial results of an NIS that is based on an intracortical microelectrode sensor that derives control signals from the motor cortex.We review recent findings showing, first, that neurons engaged by movement intentions persist in motor cortex years after injury or disease to the motor system, and second, that signals derived from motor cortex can be used by persons with paralysis to operate a range of devices. We suggest that, with further development, this form of NIS holds promise as a useful new neurotechnology for those with limited motor function or communication.We also discuss the additional potential for neural sensors to be used in the diagnosis and management of various neurological conditions and as a new way to learn about human brain function.

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pdf preprint pdf from publisher DOI [BibTex]

pdf preprint pdf from publisher DOI [BibTex]


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Cluster expansions in multicomponent systems: precise expansions from noisy databases

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

{Journal of Physics: Condensed Matter}, 19, 2007 (article)

mms

DOI [BibTex]

DOI [BibTex]


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Unusual propagation of magnetic avalanches in gold covered MgB2

Albrecht, J., Matveev, A. T., Habermeier, H.-U.

{Physica C}, 460-462, pages: 1245-1246, 2007 (article)

mms

DOI [BibTex]

DOI [BibTex]


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Lowering of the L10 ordering temperature of FePt nanoparticles by He+ ion irradiation

Wiedwald, U., Klimmer, A., Kern, B., Han, L., Boyen, H.-G., Ziemann, P., Fauth, K.

{Applied Physics Letters}, 90, 2007 (article)

mms

[BibTex]

[BibTex]


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Magnetic core shell nanoparticles characterized by X-ray absorption and magnetic circular dichroism

Fauth, K.

{Modern Physics Letters B}, 21(18):1179-1187, 2007 (article)

mms

[BibTex]

[BibTex]


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Magnetic moment of Fe in oxide-free FePt nanoparticles

Dmitrieva, O., Spasova, M., Antoniak, C., Acet, M., Dumpich, G., Kästner, J., Farle, M., Fauth, K., Wiedwald, U., Boyen, H.-G., Ziemann, P.

{Physical Review B}, 76, 2007 (article)

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[BibTex]

[BibTex]


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The effect of bismuth segregation on the faceting of \Sigma3 and \Sigma9 coincidence boundaries in copper bicrystals

Straumal, B. B., Polyakov, S. A., Chang, L.-S., Mittemeijer, E. J.

{International Journal of Materials Research}, 98, pages: 451-456, 2007 (article)

mms

[BibTex]

[BibTex]


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Hot isostatic pressing of Cu-Bi polycrystals with liquid-like grain boundary layers

Chang, L.-S., Straumal, B., Rabkin, E., Lojkowski, W., Gust, W.

{Acta Materialia}, 55, pages: 335-343, 2007 (article)

mms

[BibTex]

[BibTex]


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Spatially resolved magnetic response in core shell nanoparticles

Fauth, K., Goering, E., Theil Kuhn, L.

{Modern Physics Letters B}, 21(18):1197-1200, 2007 (article)

mms

[BibTex]

[BibTex]


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Interfaces in semiconductor/metal radial superlattices

Deneke, C., Sigle, W., Eigenthaler, U., van Aken, P. A., Schütz, G., Schmidt, O. G.

{Applied Physics Letters}, 90, 2007 (article)

mms

[BibTex]

[BibTex]


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Live cell adhesion assay with attenuated total reflection infrared spectroscopy

Schmidt, M., Wolfram, T., Rumpler, M., Tripp, C. P., Grunze, M.

{Biointerphases}, 2(1):1-5, 2007 (article)

mms

[BibTex]

[BibTex]


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Unusual Co moment reduction in the NiCoO/Co exchange bias system

Brück, S., Goering, E., Tang, Y. J., Schütz, G., Berkowitz, A. E.

{Journal of Magnetism and Magnetic Materials}, 310, pages: 2316-2318, 2007 (article)

mms

[BibTex]

[BibTex]


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Adhesion of biologically inspired vertical and angled polymer microfiber arrays

Aksak, B., Murphy, M. P., Sitti, M.

Langmuir, 23(6):3322-3332, ACS Publications, 2007 (article)

pi

Project Page [BibTex]

Project Page [BibTex]


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Waalbot: An agile small-scale wall-climbing robot utilizing dry elastomer adhesives

Murphy, M. P., Sitti, M.

IEEE/ASME transactions on Mechatronics, 12(3):330-338, IEEE, 2007 (article)

pi

[BibTex]

[BibTex]


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Denoising archival films using a learned Bayesian model

Moldovan, T. M., Roth, S., Black, M. J.

(CS-07-03), Brown University, Department of Computer Science, 2007 (techreport)

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pdf [BibTex]

pdf [BibTex]


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Ab initio calculations of adiabatic magnon spectra using the atomic-sphere aproximation for the spin direction

Singer, R., Dietermann, F., Steiauf, D., Fähnle, M.

{Physical Review B}, 76, 2007 (article)

mms

DOI [BibTex]

DOI [BibTex]


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Low-temperature thermal-desorption mass spectroscopy applied to investigate the hydrogen adsorption on porous materials

Panella, B., Hirscher, M., Ludescher, B.

{Microporous and Mesoporous Materials}, 103, pages: 230-234, 2007 (article)

mms

[BibTex]


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Dependence of the critical temperature of YBCO thin films on spinpolarized quasiparticle injection

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

{International Journal of Modern Physics B}, 21(18 \& 19):3303-3306, 2007 (article)

mms

[BibTex]

[BibTex]


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Copper alloys for the restoration of reed pipes in historic organs

Straumal, B. B., Baretzky, B., Kalnins, J., Aslund, A., Friesel, M.

{Journal of Functional Materials}, 1, pages: 4-10, 2007 (article)

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[BibTex]

[BibTex]


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Inhomogeneous vortex distribution and magnetic coupling in oxide superconductor-ferromagnet hybrids

Albrecht, J., Djupmyr, M., Soltan, S., Habermeier, H.-U., Connolly, M. R., Bending, S. J.

{New Journal of Physics}, 9, 2007 (article)

mms

DOI [BibTex]

DOI [BibTex]


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Metal hydride materials for solid hydrogen storage: a review

Sakintuna, B., Lamari-Darkrim, F., Hirscher, M.

{International Journal of Hydrogen Energy}, 32, pages: 1121-1140, 2007 (article)

mms

[BibTex]

[BibTex]


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Thermal reversal of exchange spring composite media in magnetic fields

Goll, D., Macke, S., Bertram, H. N.

{Applied Physics Letters}, 90, 2007 (article)

mms

[BibTex]

[BibTex]


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Magnetism of Co-doped ZnO thin films

Gacic, M., Jakob, G., Herbort, C., Adrian, H., Tietze, T., Brück, S., Goering, E.

{Physical Review B}, 75, 2007 (article)

mms

DOI [BibTex]

DOI [BibTex]


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iCub - The Design and Realization of an Open Humanoid Platform for Cognitive and Neuroscience Research

Tsagarakis, N., Metta, G., Sandini, G., Vernon, D., Beira, R., Becchi, F., Righetti, L., Santos-Victor, J., Ijspeert, A., Carrozza, M., Caldwell, D.

Advanced Robotics, 21(10):1151-1175, 2007 (article)

Abstract
The development of robotic cognition and the advancement of understanding of human cognition form two of the current greatest challenges in robotics and neuroscience, respectively. The RobotCub project aims to develop an embodied robotic child (iCub) with the physical (height 90 cm and mass less than 23 kg) and ultimately cognitive abilities of a 2.5-year-old human child. The iCub will be a freely available open system which can be used by scientists in all cognate disciplines from developmental psychology to epigenetic robotics to enhance understanding of cognitive systems through the study of cognitive development. The iCub will be open both in software, but more importantly in all aspects of the hardware and mechanical design. In this paper the design of the mechanisms and structures forming the basic 'body' of the iCub are described. The papers considers kinematic structures dynamic design criteria, actuator specification and selection, and detailed mechanical and electronic design. The paper concludes with tests of the performance of sample joints, and comparison of these results with the design requirements and simulation projects.

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link (url) DOI [BibTex]

link (url) DOI [BibTex]


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Subfeature patterning of organic and inorganic materials using robotic assembly

Tafazzoli, A., Cheng, C., Pawashe, C., Sabo, E. K., Trofin, L., Sitti, M., LeDuc, P. R.

Journal of materials research, 22(06):1601-1608, Cambridge University Press, 2007 (article)

pi

[BibTex]

[BibTex]