672 research outputs found

    Monadicity of the Bousfield-Kuhn functor

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    We consider the localization of the ∞\infty-category of spaces at the vnv_n-periodic equivalences, the case n=0n=0 being rational homotopy theory. We prove that this localization is for n≥1n\geq 1 equivalent to algebras over a certain monad on the ∞\infty-category of T(n)T(n)-local spectra. This monad is built from the Bousfield--Kuhn functor

    Laser pulse analysis

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    Methods are presented for locating threshold points by using laser pulse analysis. It was found that there are errors involved in the determination of each of these quantities, and an attempt was made to separate their effects on the overall range correction. Several series of corrected range measurements for fixed reflectors and satellites were obtained. Residuals were computed by fitting the range measurements to either fixed-reflector distances or short arcs of satellite orbits. Root mean square values of these residuals are presented

    The Phoenix Pluto Probe

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    A design proposal for an unmanned probe to Pluto is presented. The topics covered include: (1) scientific instrumentation; (2) mission management, planning, and costing; (3) power and propulsion system; (4) structural subsystem; (5) command, control, and communication; and (6) attitude and articulation control

    Improvement of normalization methods for eigenvector derivatives

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    Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/76868/1/AIAA-11108-459.pd

    Letters from Chas. Eldered Shelton, John L. Tilton, George Clammer, and Wallace R. Lane

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    Letters concerning A. G. Reid, an applicant for position in athletic department at Utah Agricultural College

    Simulating 50 kev x-ray photon detection in silicon with a down-conversion layer

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    Simulation results are presented that explore an innovative, new design for X-ray detection in the 20–50 keV range that is an alternative to traditional direct and indirect detection methods. Typical indirect detection using a scintillator must trade-off between absorption efficiency and spatial resolution. With a high-Z layer that down-converts incident photons on top of a silicon detector, this design has increased absorption efficiency without sacrificing spatial resolution. Simulation results elucidate the relationship between the thickness of each layer and the number of photoelectrons generated. Further, the physics behind the production of electron-hole pairs in the silicon layer is studied via a second model to shed more light on the detector’s functionality. Together, the two models provide a greater understanding of this detector and reveal the potential of this novel form of X-ray detection

    Flexible structure control laboratory development and technology demonstration

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    An experimental structure is described which was constructed to demonstrate and validate recent emerging technologies in the active control and identification of large flexible space structures. The configuration consists of a large, 20 foot diameter antenna-like flexible structure in the horizontal plane with a gimballed central hub, a flexible feed-boom assembly hanging from the hub, and 12 flexible ribs radiating outward. Fourteen electrodynamic force actuators mounted to the hub and to the individual ribs provide the means to excite the structure and exert control forces. Thirty permanently mounted sensors, including optical encoders and analog induction devices provide measurements of structural response at widely distributed points. An experimental remote optical sensor provides sixteen additional sensing channels. A computer samples the sensors, computes the control updates and sends commands to the actuators in real time, while simultaneously displaying selected outputs on a graphics terminal and saving them in memory. Several control experiments were conducted thus far and are documented. These include implementation of distributed parameter system control, model reference adaptive control, and static shape control. These experiments have demonstrated the successful implementation of state-of-the-art control approaches using actual hardware

    Dysfunction of Mitral Ball Valve Prosthesis

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    Three case histories of patients with malfunctions of Smeloff-Cutter mitral ball valve prostheses are presented here - one underwent successful replacement. The clinical diagnosis was made by observing a marked variation in the A2OC interval and intermittent absence of the opening click. Phonocardiograms were diagnostic in all three cases. while echocardiograms and even angiograms did not uniformly diagnose prosthetic valve dysfunction. Periodic phonocardiographic evaluations may be helpful in early detection of the prosthetic valve dysfunction. Once the diagnosis is established, immediate surgical treatment is imperative to prevent sudden death

    Electron Cloud Measurements in Fermilab Booster

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    Fermilab Booster synchrotron requires an intensity upgrade from 4.5x1012 to 6.5x1012 protons per pulse as a part of Fermilab's Proton Improvement Plan-II (PIP-II). One of the factors which may limit the high-intensity performance is the fast transverse instabilities caused by electron cloud effects. According to the experience in the Recycler, the electron cloud gradually builds up over multiple turns inside the combined function magnets and can reach final intensities orders of magnitude greater than in a pure dipole. Since the Booster synchrotron also incorporates combined function magnets, it is important to measure the presence of electron cloud. The presence or apparent absence of the electron cloud was investigated using two different methods: measuring bunch-by-bunch tune shift by changing the bunch train structure at different intensities and propagating a microwave carrier signal through the beampipe and analyzing the phase modulation of the signal. This paper presents the results of the two methods and corresponding simulation results conducted using PyECLOUD software.Comment: International Particle Accelerator Conference 202
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