899 research outputs found
Study of bonding between glass and plastic in glass-reinforced plastics - Extended work Quarterly progress report, 1 Jan. - 31 Mar. 1967
Procedures for fluorination and alkylation of glass fabric for subsequent use in production of laminate
RDF Querying
Reactive Web systems, Web services, and Web-based publish/
subscribe systems communicate events as XML messages, and in
many cases require composite event detection: it is not sufficient to react
to single event messages, but events have to be considered in relation to
other events that are received over time.
Emphasizing language design and formal semantics, we describe the
rule-based query language XChangeEQ for detecting composite events.
XChangeEQ is designed to completely cover and integrate the four complementary
querying dimensions: event data, event composition, temporal
relationships, and event accumulation. Semantics are provided as
model and fixpoint theories; while this is an established approach for rule
languages, it has not been applied for event queries before
Universal Power Law in the Noise from a Crumpled Elastic Sheet
Using high-resolution digital recordings, we study the crackling sound
emitted from crumpled sheets of mylar as they are strained. These sheets
possess many of the qualitative features of traditional disordered systems
including frustration and discrete memory. The sound can be resolved into
discrete clicks, emitted during rapid changes in the rough conformation of the
sheet. Observed click energies range over six orders of magnitude. The measured
energy autocorrelation function for the sound is consistent with a stretched
exponential C(t) ~ exp(-(t/T)^{b}) with b = .35. The probability distribution
of click energies has a power law regime p(E) ~ E^{-a} where a = 1. We find the
same power law for a variety of sheet sizes and materials, suggesting that this
p(E) is universal.Comment: 5 pages (revtex), 10 uuencoded postscript figures appended, html
version at http://rainbow.uchicago.edu/~krame
Edge electron states for quasi-one-dimensional organic conductors in the magnetic-field-induced spin-density-wave phases
We develop a microscopic picture of the electron states localized at the
edges perpendicular to the chains in the Bechgaard salts in the quantum Hall
regime. In a magnetic-field-induced spin-density-wave state (FISDW)
characterized by an integer N, there exist N branches of chiral gapless edge
excitations. Localization length is much longer and velocity much lower for
these states than for the edge states parallel to the chains. We calculate the
contribution of these states to the specific heat and propose a time-of-flight
experiment to probe the propagating edge modes directly.Comment: 4 pages, 2 figures. V.2: Minor changes to the final version published
in PR
The Mission Accessibility of Near-Earth Asteroids
The population of near-Earth asteroids (NEAs) that may be accessible for human space flight missions is defined by the Near-Earth Object Human Space Flight Accessible Targets Study (NHATS). The NHATS is an automated system designed to monitor the accessibility of, and particular mission opportunities offered by, the NEA population. This is analogous to systems that automatically monitor the impact risk posed to Earth by the NEA population. The NHATS system identifies NEAs that are potentially accessible for future round-trip human space flight missions and provides rapid notification to asteroid observers so that crucial follow-up observations can be obtained following discovery of accessible NEAs. The NHATS was developed in 2010 and was automated by early 2012. NHATS data are provided via an interactive web-site, and daily NHATS notification emails are transmitted to a mailing list; both resources are available to the public
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