10,093 research outputs found
Automatically Leveraging MapReduce Frameworks for Data-Intensive Applications
MapReduce is a popular programming paradigm for developing large-scale,
data-intensive computation. Many frameworks that implement this paradigm have
recently been developed. To leverage these frameworks, however, developers must
become familiar with their APIs and rewrite existing code. Casper is a new tool
that automatically translates sequential Java programs into the MapReduce
paradigm. Casper identifies potential code fragments to rewrite and translates
them in two steps: (1) Casper uses program synthesis to search for a program
summary (i.e., a functional specification) of each code fragment. The summary
is expressed using a high-level intermediate language resembling the MapReduce
paradigm and verified to be semantically equivalent to the original using a
theorem prover. (2) Casper generates executable code from the summary, using
either the Hadoop, Spark, or Flink API. We evaluated Casper by automatically
converting real-world, sequential Java benchmarks to MapReduce. The resulting
benchmarks perform up to 48.2x faster compared to the original.Comment: 12 pages, additional 4 pages of references and appendi
Trident: a universal tool for generating synthetic absorption spectra from astrophysical simulations
Hydrodynamical simulations are increasingly able to accurately model physical
systems on stellar, galactic, and cosmological scales, however, the utility of
these simulations is often limited by our ability to directly compare them with
the datasets produced by observers: spectra, photometry, etc. To address this
problem, we have created Trident}, a Python-based, open-source tool for
post-processing hydrodynamical simulations to produce synthetic absorption
spectra and related data. Trident} can (i) create absorption-line spectra for
any trajectory through a simulated dataset mimicking both background quasar and
down-the-barrel configurations, (ii) reproduce the spectral characteristics of
common instruments like the Cosmic Origins Spectrograph, (iii) operate across
the ultraviolet, optical and infrared using customizable absorption line lists,
(iv) trace simulated physical structures directly to spectral features, (v)
approximate the presence of ion species absent from the simulation outputs,
(vi) generate column density maps for any ion, and (vii) provide support for
all major astrophysical hydrodynamical codes. The focus of Trident's
development is for using simulated datasets to better interpret observations of
the circumgalactic medium (CGM) and intergalactic medium (IGM), but it remains
a general tool applicable in other contexts.Comment: 16 pages, 13 figures, published in ApJ, Code available at
http://trident-project.or
Advanced transport operating system software upgrade: Flight management/flight controls software description
The Flight Management/Flight Controls (FM/FC) software for the Norden 2 (PDP-11/70M) computer installed on the NASA 737 aircraft is described. The software computes the navigation position estimates, guidance commands, those commands to be issued to the control surfaces to direct the aircraft in flight based on the modes selected on the Advanced Guidance Control System (AGSC) mode panel, and the flight path selected via the Navigation Control/Display Unit (NCDU)
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