362 research outputs found

    Summability methods based on the Riemann Zeta function

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    This paper is a study of summability methods that are based on the Riemann Zeta function. A limitation theorem is proved which gives a necessary condition for a sequence x to be zeta summable. A zeta summability matrix Zt associated with a real sequence t is introduced; a necessary and sufficient condition on the sequence t such that Zt maps l1 to l1 is established. Results comparing the strength of the zeta method to that of well-known summability methods are also investigated

    Protocols for calibrating multibeam sonar

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    Development of protocols for calibrating multibeam sonar by means of the standard-target method is documented. Particular systems used in the development work included three that provide the water-column signals, namely the SIMRAD SM2000/90- and 200-kHz sonars and RESON SeaBat 8101 sonar, with operating frequency of 240 kHz. Two facilities were instrumented specifically for the work: a sea well at the Woods Hole Oceanographic Institution and a large, indoor freshwater tank at the University of New Hampshire. Methods for measuring the transfer characteristics of each sonar, with transducers attached, are described and illustrated with measurement results. The principal results, however, are the protocols themselves. These are elaborated for positioning the target, choosing the receiver gain function, quantifying the system stability, mapping the directionality in the plane of the receiving array and in the plane normal to the central axis, measuring the directionality of individual beams, and measuring the nearfield response. General preparations for calibrating multibeam sonars and a method for measuring the receiver response electronically are outlined. Advantages of multibeam sonar calibration and outstanding problems, such as that of validation of the performance of multibeam sonars as configured for use, are mentioned

    A micromachined 2D positioner with electrothermal actuation and sub-nanometer capacitive sensing

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    This paper reports on a multi-purpose two-axis micropositioner with sub-nanometer position sensing for precise feedback control. Along each axis it has an electrothermal actuator, a capacitive position sensor and a displacement amplifier that provides a gain of 3.37 for the sensor. It is fabricated from custom SOI wafers using dry etching, and each component is electrically and thermally isolated by silicon nitride. For a fabricated device of 65 ÎŒm thickness, the measured displacement sensitivity is 0.333 fF nm−1, which corresponds to 0.3 nm resolution with available laboratory instrumentation. The range is ≈19 ÎŒm along each axis for the positioner, which corresponds to 66 ÎŒm travel in the sense combs. Using an external parallel inductor, a positioning displacement of 9.6 ÎŒm offers a shift of 240 kHz in L–C resonance, corresponding to a sensitivity of 25 Hz nm−1.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/49040/2/jm3216.pd

    Focused Ion Beam Microfabrication

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    Contains an introduction, reports on seven research projects and a list of publications.Defense Advanced Research Projects Agency/U.S. Army Research Office Contract DAAL03-88-K-0108National Science Foundation Grant ECS 89-21728U.S. Army Research Office Contract DAAL03-87-K-0126U.S. Navy - Naval Research Laboratory/Micrion Agreement M08774SEMATEC

    Detection of Novel SARS-like and Other Coronaviruses in Bats from Kenya

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    Diverse coronaviruses have been identified in bats from several continents but not from Africa. We identified group 1 and 2 coronaviruses in bats in Kenya, including SARS-related coronaviruses. The sequence diversity suggests that bats are well-established reservoirs for and likely sources of coronaviruses for many species, including humans

    Focused Ion Beam Fabrication

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    Contains reports on thirteen research projects and a list of publications.Defense Advanced Research Projects Agency/U.S. Army Research Office Contract DAAL03-88-K-0108National Science Foundation Grant ECS 89-21728MIT Lincoln Laboratory Innovative Research ProgramSEMATECH Contract 90-MC-503Micrion Contract M08774U.S. Army Research Office Contract DAAL03-87-K-0126IBM Corporatio

    Prime Focus Spectrograph (PFS) for the Subaru Telescope: Overview, recent progress, and future perspectives

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    PFS (Prime Focus Spectrograph), a next generation facility instrument on the 8.2-meter Subaru Telescope, is a very wide-field, massively multiplexed, optical and near-infrared spectrograph. Exploiting the Subaru prime focus, 2394 reconfigurable fibers will be distributed over the 1.3 deg field of view. The spectrograph has been designed with 3 arms of blue, red, and near-infrared cameras to simultaneously observe spectra from 380nm to 1260nm in one exposure at a resolution of ~1.6-2.7A. An international collaboration is developing this instrument under the initiative of Kavli IPMU. The project is now going into the construction phase aiming at undertaking system integration in 2017-2018 and subsequently carrying out engineering operations in 2018-2019. This article gives an overview of the instrument, current project status and future paths forward.Comment: 17 pages, 10 figures. Proceeding of SPIE Astronomical Telescopes and Instrumentation 201
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