6,777 research outputs found
Reduction of magnetostatic interactions in self-organized arrays of nickel nanowires using atomic layer deposition
Ordered arrays of magnetic nanowires are commonly synthesized by
electrodeposition in nanoporous alumina templates. Due to their dense packing,
strong magnetostatic interactions prevent the manipulation of wires
individually. Using atomic layer deposition we reduce the diameter of the pores
prior to electrodeposition. This reduces magnetostatic interactions, yielding
fully remanent hysteresis loops. This is a first step towards the use of such
arrays for magnetic racetrack memories
Design exploration and performance strategies towards power-efficient FPGA-based achitectures for sound source localization
Many applications rely on MEMS microphone arrays for locating sound sources prior to their execution. Those applications not only are executed under real-time constraints but also are often embedded on low-power devices. These environments become challenging when increasing the number of microphones or requiring dynamic responses. Field-Programmable Gate Arrays (FPGAs) are usually chosen due to their flexibility and computational power. This work intends to guide the design of reconfigurable acoustic beamforming architectures, which are not only able to accurately determine the sound Direction-Of-Arrival (DoA) but also capable to satisfy the most demanding applications in terms of power efficiency. Design considerations of the required operations performing the sound location are discussed and analysed in order to facilitate the elaboration of reconfigurable acoustic beamforming architectures. Performance strategies are proposed and evaluated based on the characteristics of the presented architecture. This power-efficient architecture is compared to a different architecture prioritizing performance in order to reveal the unavoidable design trade-offs
Central production via photon-photon fusion in proton-proton collisions with proton dissociation
We present a formalism which uses fluxes of equivalent photons including
transverse momenta of the intermediate photons. The formalism reminds the
familiar -factorization approach used, e.g., to study the two-photon
production of or pairs. The results of the new method are
compared with those obtained using the code LPAIR, and a good agreement is
obtained. The inclusion of the photon transverse momenta is necessary in
studies of correlation observables. We present distributions for the dimuon
invariant mass, transverse momentum of the muon pair and relative azimuthal
angle between muons separately for elastic-elastic, elastic-inelastic,
inelastic-elastic and inelastic-inelastic mechanisms. For typical experimental
cuts all mechanisms give similar contributions. The results are shown for
different sets of cuts relevant for the LHC experiments. The cross sections in
different regions of phase space depend on structure function in
different regions of and . A comment on is made.Comment: 24 pages, 36 figures, 2 table
SoundCompass: a distributed MEMS microphone array-based sensor for sound source localization
Sound source localization is a well-researched subject with applications ranging from localizing sniper fire in urban battlefields to cataloging wildlife in rural areas. One critical application is the localization of noise pollution sources in urban environments, due to an increasing body of evidence linking noise pollution to adverse effects on human health. Current noise mapping techniques often fail to accurately identify noise pollution sources, because they rely on the interpolation of a limited number of scattered sound sensors. Aiming to produce accurate noise pollution maps, we developed the SoundCompass, a low-cost sound sensor capable of measuring local noise levels and sound field directionality. Our first prototype is composed of a sensor array of 52 Microelectromechanical systems (MEMS) microphones, an inertial measuring unit and a low-power field-programmable gate array (FPGA). This article presents the SoundCompass's hardware and firmware design together with a data fusion technique that exploits the sensing capabilities of the SoundCompass in a wireless sensor network to localize noise pollution sources. Live tests produced a sound source localization accuracy of a few centimeters in a 25-m2 anechoic chamber, while simulation results accurately located up to five broadband sound sources in a 10,000-m2 open field
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