4,073 research outputs found

    Shelf and cycle life evaluation of silver-zinc cells

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    Silver-zinc cells having a separator system of cross-linked high-density polyethylene with a methacrylic acid graft withstand corrosion when subjected to thermal sterilization treatments

    Three-dimensional formation flying using bifurcating potential fields

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    This paper describes the design of a three-dimensional formation flying guidance and control algorithm for a swarm of autonomous Unmanned Aerial Vehicles (UAVs), using the new approach of bifurcating artificial potential fields. We consider a decentralized control methodology that can create verifiable swarming patterns, which guarantee obstacle and vehicle collision avoidance. Based on a steering and repulsive potential field the algorithm supports flight that can transition between different formation patterns by way of a simple parameter change. The algorithm is applied to linear longitudinal and lateral models of a UAV. An experimental system to demonstrate formation flying is also developed to verify the validity of the proposed control system

    Ab initio study of reflectance anisotropy spectra of a sub-monolayer oxidized Si(100) surface

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    The effects of oxygen adsorption on the reflectance anisotropy spectrum (RAS) of reconstructed Si(100):O surfaces at sub-monolayer coverage (first stages of oxidation) have been studied by an ab initio DFT-LDA scheme within a plane-wave, norm-conserving pseudopotential approach. Dangling bonds and the main features of the characteristic RAS of the clean Si(100) surface are mostly preserved after oxidation of 50% of the surface dimers, with some visible changes: a small red shift of the first peak, and the appearance of a distinct spectral structure at about 1.5 eV. The electronic transitions involved in the latter have been analyzed through state-by-state and layer-by-layer decompositions of the RAS. We suggest that new interplay between present theoretical results and reflectance anisotropy spectroscopy experiments could lead to further clarification of structural and kinetic details of the Si(100) oxidation process in the sub-monolayer range.Comment: 21 pages, 8 figures. To be published in Physical Rev.

    The Timing Counter of the MEG experiment: calibration and performance

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    The MEG detector is designed to test Lepton Flavor Violation in the μ+e+γ\mu^+\rightarrow e^+\gamma decay down to a Branching Ratio of a few 101310^{-13}. The decay topology consists in the coincident emission of a monochromatic photon in direction opposite to a monochromatic positron. A precise measurement of the relative time te+γt_{e^+\gamma} is crucial to suppress the background. The Timing Counter (TC) is designed to precisely measure the time of arrival of the e+e^+ and to provide information to the trigger system. It consists of two sectors up and down stream the decay target, each consisting of two layers. The outer one made of scintillating bars and the inner one of scintillating fibers. Their design criteria and performances are described.Comment: Presented at the 12th Topical Seminar on Innovative Particle and Radiation Detectors (IPRD10) 7 - 10 June 2010, Siena. Accepted by Nuclear Physics B (Proceedings Supplements) (2011)tal

    Topological-charge anomalies in supersymmetric theories with domain walls

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    Domain walls in 1+2 dimensions are studied to clarify some general features of topological-charge anomalies in supersymmetric theories, by extensive use of a superfield supercurrent. For domain walls quantum modifications of the supercharge algebra arise not only from the short-distance anomaly but also from another source of long-distance origin, induced spin in the domain-wall background, and the latter dominates in the sum. A close look into the supersymmetric trace identity, which naturally accommodates the central-charge anomaly and its superpartners, shows an interesting consequence of the improvement of the supercurrent: Via an improvement the anomaly in the central charge can be transferred from induced spin in the fermion sector to an induced potential in the boson sector. This fact reveals a dual character, both fermionic and bosonic, of the central-charge anomaly, which reflects the underlying supersymmetry. The one-loop superfield effective action is also constructed to verify the anomaly and BPS saturation of the domain-wall spectrum.Comment: 8 pages, Revte

    Transformation in Lotus Corniculatus: Towards Low-Lignin Pasture Through Antisense RNA

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    We have developed a rapid and reproducible transformation system for bird’s-foot trefoil (Lotus corniculatus L.) by using Agrobacterium-mediated T-DNA transfer and the incorporation of the antisense gene for cinnamyl alcohol dehydrogenase (CAD) from Aralia cordata into Lotus for lignin reduction. The presence of the transferred antisense gene in regenerated plants has been confirmed by PCR analysis
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