17,217 research outputs found
An information-theoretic approach to the gravitational-wave burst detection problem
The observational era of gravitational-wave astronomy began in the Fall of
2015 with the detection of GW150914. One potential type of detectable
gravitational wave is short-duration gravitational-wave bursts, whose waveforms
can be difficult to predict. We present the framework for a new detection
algorithm for such burst events -- \textit{oLIB} -- that can be used in
low-latency to identify gravitational-wave transients independently of other
search algorithms. This algorithm consists of 1) an excess-power event
generator based on the Q-transform -- \textit{Omicron} --, 2) coincidence of
these events across a detector network, and 3) an analysis of the coincident
events using a Markov chain Monte Carlo Bayesian evidence calculator --
\textit{LALInferenceBurst}. These steps compress the full data streams into a
set of Bayes factors for each event; through this process, we use elements from
information theory to minimize the amount of information regarding the
signal-versus-noise hypothesis that is lost. We optimally extract this
information using a likelihood-ratio test to estimate a detection significance
for each event. Using representative archival LIGO data, we show that the
algorithm can detect gravitational-wave burst events of astrophysical strength
in realistic instrumental noise across different burst waveform morphologies.
We also demonstrate that the combination of Bayes factors by means of a
likelihood-ratio test can improve the detection efficiency of a
gravitational-wave burst search. Finally, we show that oLIB's performance is
robust against the choice of gravitational-wave populations used to model the
likelihood-ratio test likelihoods
Finish Them!: Pricing Algorithms for Human Computation
Given a batch of human computation tasks, a commonly ignored aspect is how
the price (i.e., the reward paid to human workers) of these tasks must be set
or varied in order to meet latency or cost constraints. Often, the price is set
up-front and not modified, leading to either a much higher monetary cost than
needed (if the price is set too high), or to a much larger latency than
expected (if the price is set too low). Leveraging a pricing model from prior
work, we develop algorithms to optimally set and then vary price over time in
order to meet a (a) user-specified deadline while minimizing total monetary
cost (b) user-specified monetary budget constraint while minimizing total
elapsed time. We leverage techniques from decision theory (specifically, Markov
Decision Processes) for both these problems, and demonstrate that our
techniques lead to upto 30\% reduction in cost over schemes proposed in prior
work. Furthermore, we develop techniques to speed-up the computation, enabling
users to leverage the price setting algorithms on-the-fly
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