2,246 research outputs found

    Efficient Video Indexing on the Web: A System that Leverages User Interactions with a Video Player

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    In this paper, we propose a user-based video indexing method, that automatically generates thumbnails of the most important scenes of an online video stream, by analyzing users' interactions with a web video player. As a test bench to verify our idea we have extended the YouTube video player into the VideoSkip system. In addition, VideoSkip uses a web-database (Google Application Engine) to keep a record of some important parameters, such as the timing of basic user actions (play, pause, skip). Moreover, we implemented an algorithm that selects representative thumbnails. Finally, we populated the system with data from an experiment with nine users. We found that the VideoSkip system indexes video content by leveraging implicit users interactions, such as pause and thirty seconds skip. Our early findings point toward improvements of the web video player and its thumbnail generation technique. The VideSkip system could compliment content-based algorithms, in order to achieve efficient video-indexing in difficult videos, such as lectures or sports.Comment: 9 pages, 3 figures, UCMedia 2010: 2nd International ICST Conference on User Centric Medi

    Magnetic domain structure and dynamics in interacting ferromagnetic stacks with perpendicular anisotropy

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    The time and field dependence of the magnetic domain structure at magnetization reversal were investigated by Kerr microscopy in interacting ferromagnetic Co/Pt multilayers with perpendicular anisotropy. Large local inhomogeneous magnetostatic fields favor mirroring domain structures and domain decoration by rings of opposite magnetization. The long range nature of these magnetostatic interactions gives rise to ultra-slow dynamics even in zero applied field, i.e. it affects the long time domain stability. Due to this additionnal interaction field, the magnetization reversal under short magnetic field pulses differs markedly from the well-known slow dynamic behavior. Namely, in high field, the magnetization of the coupled harder layer has been observed to reverse more rapidly by domain wall motion than the softer layer alone.Comment: 42 pages including 17 figures. submitted to JA

    Second phalanx shortening osteotomy. An innovative technique for long second toe syndrome

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    AbstractLong second-toe syndrome, although frequent and disabling, has been little described. Current surgical techniques often lead to loss of function. Based on anatomical and biomechanical observations, the present study reports a second phalanx shortening osteotomy technique. The procedure is relatively non-invasive, involving self-stabilizing segment resection osteotomy of the second phalanx. Results for the first 23 feet undergoing the procedure were analyzed retrospectively. Assessment comprised clinical examination, radiography and AOFAS and FAAM scores. Mean follow-up was 19±9.9months. Second phalanx shortening osteotomy proved reliable, respecting the biomechanics of the toe

    Thermoelectric cross-plane properties on p- and n-Ge/SixGe1-x superlattices

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    Silicon and germanium materials have demonstrated an increasing attraction for energy harvesting, due to their sustainability and integrability with complementary metal oxide semiconductor and micro-electro-mechanical-system technology. The thermoelectric efficiencies for these materials, however, are very poor at room temperature and so it is necessary to engineer them in order to compete with telluride based materials, which have demonstrated at room temperature the highest performances in literature [1]. Micro-fabricated devices consisting of mesa structures with integrated heaters, thermometers and Ohmic contacts were used to extract the cross-plane values of the Seebeck coefficient and the thermal conductivity from p- and n-Ge/SixGe1-x superlattices. A second device consisting in a modified circular transfer line method structure was used to extract the electrical conductivity of the materials. A range of p-Ge/Si0.5Ge0.5 superlattices with different doping levels was investigated in detail to determine the role of the doping density in dictating the thermoelectric properties. A second set of n-Ge/Si0.3Ge0.7 superlattices was fabricated to study the impact that quantum well thickness might have on the two thermoelectric figures of merit, and also to demonstrate a further reduction of the thermal conductivity by scattering phonons at different wavelengths. This technique has demonstrated to lower the thermal conductivity by a 25% by adding different barrier thicknesses per period

    Operation of HVDC Modular Multilevel Converters under DC pole imbalances

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    MVDC for utility scale power distribution and control

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    This poster outlines the case for converting selected network assets to medium voltage dc to increase network performance via a series of load flow studies. Technology readiness level and research requirements for the technology are also outlined

    The assembly history of the nearest S0 galaxy NGC 3115 from its kinematics out to six half-light radii

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    Using new and archival data, we study the kinematic properties of the nearest field S0 galaxy, NGC 3115, out to 6.5\sim6.5 half-light radii (ReR_\mathrm{e}) from its stars (integrated starlight), globular clusters (GCs) and planetary nebulae (PNe). We find evidence of three kinematic regions with an inner transition at 0.2 Re\sim0.2\ R_\mathrm{e} from a dispersion-dominated bulge (Vrot/σ<1V_\mathrm{rot}/\sigma <1) to a fast-rotating disk (Vrot/σ>1V_\mathrm{rot}/\sigma >1), and then an additional transition from the disk to a slowly rotating spheroid at 22.5Re\sim2-2.5\, R_\mathrm{e}, as traced by the red GCs and PNe (and possibly by the blue GCs beyond 5Re\sim5\, R_\mathrm{e}). From comparison with simulations, we propose an assembly history in which the original progenitor spiral galaxy undergoes a gas-rich minor merger that results in the embedded kinematically cold disk that we see today in NGC 3115. At a later stage, dwarf galaxies, in mini mergers (mass-ratio << 1:10), were accreted building-up the outer slowly rotating spheroid, with the central disk kinematics largely unaltered. Additionally, we report new spectroscopic observations of a sample of ultra-compact dwarfs (UCDs) around NGC 3115 with the Keck/KCWI instrument. We find that five UCDs are inconsistent with the general rotation field of the GCs, suggesting an \textit{ex-situ} origin for these objects, i.e. perhaps the remnants of tidally stripped dwarfs. A further seven UCDs follow the GC rotation pattern, suggesting an \textit{in-situ} origin and, possibly a GC-like nature.Comment: 22 pages (including 3 pages of Appendix material), 14 figures, published in MNRA
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