4,114 research outputs found
Copeland Dueling Bandits
A version of the dueling bandit problem is addressed in which a Condorcet
winner may not exist. Two algorithms are proposed that instead seek to minimize
regret with respect to the Copeland winner, which, unlike the Condorcet winner,
is guaranteed to exist. The first, Copeland Confidence Bound (CCB), is designed
for small numbers of arms, while the second, Scalable Copeland Bandits (SCB),
works better for large-scale problems. We provide theoretical results bounding
the regret accumulated by CCB and SCB, both substantially improving existing
results. Such existing results either offer bounds of the form
but require restrictive assumptions, or offer bounds of the form without requiring such assumptions. Our results offer the best of both
worlds: bounds without restrictive assumptions.Comment: 33 pages, 8 figure
Search for Gamma Ray Bursts with the Argo-YBJ Detector in Scaler Mode
We report on the search for Gamma Ray Bursts (GRBs) in the energy range 1-100
GeV in coincidence with the prompt emission detected by satellites using the
Astrophysical Radiation with Ground-based Observatory at YangBaJing (ARGO-YBJ)
air shower detector. Thanks to its mountain location (Yangbajing, Tibet, P.R.
China, 4300 m a.s.l.), active surface (about 6700 m**2 of Resistive Plate
Chambers), and large field of view (about 2 sr, limited only by the atmospheric
absorption), the ARGO-YBJ air shower detector is particularly suitable for the
detection of unpredictable and short duration events such as GRBs. The search
is carried out using the "single particle technique", i.e. counting all the
particles hitting the detector without measurement of the energy and arrival
direction of the primary gamma rays.
Between 2004 December 17 and 2009 April 7, 81 GRBs detected by satellites
occurred within the field of view of ARGO-YBJ (zenith angle < 45 deg). It was
possible to examine 62 of these for >1 GeV counterpart in the ARGO-YBJ data
finding no statistically significant emission. With a lack of detected spectra
in this energy range fluence upper limits are profitable, especially when the
redshift is known and the correction for the extragalactic absorption can be
considered. The obtained fluence upper limits reach values as low as 10**{-5}
erg cm**{-2} in the 1-100 GeV energy region.
Besides this individual search for a higher energy counterpart, a statistical
study of the stack of all the GRBs both in time and in phase was made, looking
for a common feature in the GRB high energy emission. No significant signal has
been detected.Comment: accepted for publication in Ap
Real-time digital video multiplexer synchronisation implementation with CPLD
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A Compact Apparatus for Muon Lifetime Measurement and Time Dilation Demonstration in the Undergraduate Laboratory
We describe a compact apparatus that automatically measures the charge
averaged lifetime of atmospheric muons in plastic scintillator using low-cost,
low-power electronics and that measures the stopping rate of atmospheric muons
as a function of altitude to demonstrate relativistic time dilation. The
apparatus is designed for the advanced undergraduate physics laboratory and is
suitable for field measurements.Comment: 5 pages, 2 figure
Design of an embedded iris recognition system for use with a multi-factor authentication system.
This paper describes in detail the design, manufacturing and testing of an embedded iris scanner for use with a multifactor authentication system. The design process for this project included hardware design from part selection to board design to populating. Additionally, this process included the entirety of the software development, though the iris recognition process was largely based on other works. The functional requirements for the overall multi-factor authentication system were to have three authentication methods with a thirty second window to complete all three. The system acceptance accuracy was required to be greater than 75%. Those requirements therefore dictate that the iris scanner module must also have an acceptance accuracy higher than 75% and perform iris recognition in a few seconds so that the user can gain admittance in the allotted window of time. While the hardware has been verified and tested, further development and testing is necessary on the software and image processing. This work is funded by the Department of Energy’s Kansas City National Security Campus, operated by Honeywell Federal Manufacturing & Technologies, LLC under contract number DE-NA0002839
A 5 Meps $100 USB2.0 Address-Event Monitor-Sequencer Interface
This paper describes a high-speed USB2.0 Address-
Event Representation (AER) interface that allows simultaneous
monitoring and sequencing of precisely timed AER data. This
low-cost (<$100), two chip, bus powered interface can achieve
sustained AER event rates of 5 megaevents per second (Meps).
Several boards can be electrically synchronized, allowing simultaneous
synchronized capture from multiple devices. It has three
AER ports, one for sequencing, one for monitoring and one for
passing through the monitored events. This paper also describes
the host software infrastructure that makes the board usable for a
heterogeneous mixture of AER devices and that allows recording
and playback of recorded data
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