4,225 research outputs found

    Light Powered Keyboard Charging for Full-screen Devices

    Get PDF
    This disclosure describes a detachable keyboard for use with foldable computing devices. The keyboard can be charged via illumination from the display of the foldable device. Photovoltaic cells are provided on the bottom surface of the keyboard and generate electrical power from display illumination when the keyboard is placed on the display such as an organic light emitting diode (OLED) display. The illumination intensity of the pixels located directly beneath the keyboard can be adjusted to its maximum level to enable faster charging

    Position-Based Multi-Agent Dynamics for Real-Time Crowd Simulation (MiG paper)

    Full text link
    Exploiting the efficiency and stability of Position-Based Dynamics (PBD), we introduce a novel crowd simulation method that runs at interactive rates for hundreds of thousands of agents. Our method enables the detailed modeling of per-agent behavior in a Lagrangian formulation. We model short-range and long-range collision avoidance to simulate both sparse and dense crowds. On the particles representing agents, we formulate a set of positional constraints that can be readily integrated into a standard PBD solver. We augment the tentative particle motions with planning velocities to determine the preferred velocities of agents, and project the positions onto the constraint manifold to eliminate colliding configurations. The local short-range interaction is represented with collision and frictional contact between agents, as in the discrete simulation of granular materials. We incorporate a cohesion model for modeling collective behaviors and propose a new constraint for dealing with potential future collisions. Our new method is suitable for use in interactive games.Comment: 9 page

    Radioactive Scandium in the Youngest Galactic Supernova Remnant G1.9+0.3

    Full text link
    We report the discovery of thermal X-ray emission from the youngest Galactic supernova remnant G1.9+0.3, from a 237-ks Chandra observation. We detect strong K-shell lines of Si, S, Ar, Ca, and Fe. In addition, we detect a 4.1 keV line with 99.971% confidence which we attribute to 44Sc, produced by electron capture from 44Ti. Combining the data with our earlier Chandra observation allows us to detect the line in two regions independently. For a remnant age of 100 yr, our measured total line strength indicates synthesis of (1−7)×10−5(1 - 7) \times 10^{-5} solar masses of 44Ti, in the range predicted for both Type Ia and core-collapse supernovae, but somewhat smaller than the 2×10−42 \times 10^{-4} solar masses reported for Cas A. The line spectrum indicates supersolar abundances. The Fe emission has a width of about 28,000 km/s, consistent with an age of about 100 yr and with the inferred mean shock velocity of 14,000 km/s deduced assuming a distance of 8.5 kpc. Most thermal emission comes from regions of lower X-ray but higher radio surface brightness. Deeper observations should allow more detailed spatial mapping of scandium, with significant implications for models of nucleosynthesis in Type Ia supernovae.Comment: 5 pages, 3 figures, accepted for publication in ApJ

    Nonuniform Expansion of the Youngest Galactic Supernova Remnant G1.9+0.3

    Get PDF
    We report measurements of X-ray expansion of the youngest Galactic supernova remnant, G1.9+0.3, using Chandra observations in 2007, 2009, and 2011. The measured rates strongly deviate from uniform expansion, decreasing radially by about 60% along the X-ray bright SE-NW axis from 0.84% +/- 0.06% per yr to 0.52% +/- 0.03% per yr. This corresponds to undecelerated ages of 120-190 yr, confirming the young age of G1.9+0.3, and implying a significant deceleration of the blast wave. The synchrotron-dominated X-ray emission brightens at a rate of 1.9% +/- 0.4% per yr. We identify bright outer and inner rims with the blast wave and reverse shock, respectively. Sharp density gradients in either ejecta or ambient medium are required to produce the sudden deceleration of the reverse shock or the blast wave implied by the large spread in expansion ages. The blast wave could have been decelerated recently by an encounter with a modest density discontinuity in the ambient medium, such as found at a wind termination shock, requiring strong mass loss in the progenitor. Alternatively, the reverse shock might have encountered an order-of-magnitude density discontinuity within the ejecta, such as found in pulsating delayed-detonation Type Ia models. We demonstrate that the blast wave is much more decelerated than the reverse shock in these models for remnants at ages similar to G1.9+0.3. Similar effects may also be produced by dense shells possibly associated with high-velocity features in Type Ia spectra. Accounting for the asymmetry of G1.9+0.3 will require more realistic 3D Type Ia models.Comment: 6 pages, 4 figures, accepted for publication in ApJ Letters, minor revision

    The Youngest Galactic Supernova Remnant: G1.9+0.3

    Full text link
    Our 50 ks Chandra observation of the small radio supernova remnant (SNR) G1.9+0.3 shows a complete shell structure with strong bilateral symmetry, about 100′′100'' in diameter. The radio morphology is also shell-like, but only about 84′′84'' in diameter, based on observations made in 1985. We attribute the size difference to expansion between 1985 and our Chandra observations of 2007. Expansion is confirmed in comparing radio images from 1985 and 2008. We deduce that G1.9+0.3 is of order 100 years old -- the youngest supernova remnant in the Galaxy. Based on a very high absorbing column density of 5.5×10225.5 \times 10^{22} cm−2^{-2}, we place G1.9+0.3 near the Galactic Center, at a distance of about 8.5 kpc, where the mean remnant radius would be about 2 pc, and the required expansion speed about 14,00014,000 km s−1^{-1}. The X-ray spectrum is featureless and well-described by the exponentially cut off synchrotron model {\tt srcut}. With the radio flux at 1 GHz fixed at 0.9 Jy, we find a spectral index of 0.65 and a rolloff frequency of 1.4×10181.4 \times 10^{18} Hz. The implied characteristic rolloff electron energy of about 94(B/10μG)−1/294 (B/10 \mu{\rm G})^{-1/2} TeV is the highest ever reported for a shell supernova remnant. It can easily be reached by standard diffusive shock acceleration, given the very high shock velocities; it can be well described by either age-limited or synchrotron-loss-limited acceleration. Not only is G1.9+0.3 the youngest known Galactic remnant, it is also only the fourth Galactic X-ray synchrotron-dominated shell supernova remnant.Comment: 4 pages, 5 figures; revised to include new radio data and accepted for ApJ
    • …
    corecore