2,068 research outputs found
Long Duration Exposure Facility (LDEF) structural verification test report
Structural load tests on the Long Duration Exposure Facility's (LDEF) primary structure were conducted. These tests had three purposes: (1) demonstrate structural adequacy of the assembled LDEF primary structure when subjected to anticipated flight loads; (2) verify analytical models and methods used in loads and stress analysis; and (3) perform tests to comply with the Space Transportation System (STS) requirements. Test loads were based on predicted limit loads which consider all flight events. Good agreement is shown between predicted and observed load, strain, and deflection data. Test data show that the LDEF structure was subjected to 1.2 times limit load to meet the STS requirements. The structural adequacy of the LDEF is demonstrated
Monitoring cattle behavior and pasture use with GPS and GIS
Precision agriculture is already being used commercially to improve variability management in row crop agriculture. In the same way, understanding how spatial and temporal variability of animal, forage, soil and landscape features affect grazing behavior and forage utilization provides potential to modify pasture management, improve efficiency of utilization, and maximize profits. Recent advances in global positioning system (GPS) technology have allowed the development of lightweight GPS collar receivers suitable for monitoring animal position at 5-min intervals. The GPS data can be imported into a geographic information system (GIS) to assess animal behavior characteristics and pasture utilization. This paper describes application and use of GPS technology on intensively managed beef cattle, and implications for livestock behavior and management research on pasture
Monitoring cattle behavior and pasture use with GPS and GIS
Precision agriculture is already being used commercially to improve variability management in row crop agriculture. In the same way, understanding how spatial and temporal variability of animal, forage, soil and landscape features affect grazing behavior and forage utilization provides potential to modify pasture management, improve efficiency of utilization, and maximize profits. Recent advances in global positioning system (GPS) technology have allowed the development of lightweight GPS collar receivers suitable for monitoring animal position at 5-min intervals. The GPS data can be imported into a geographic information system (GIS) to assess animal behavior characteristics and pasture utilization. This paper describes application and use of GPS technology on intensively managed beef cattle, and implications for livestock behavior and management research on pasture
The evolution of bits and bottlenecks in a scientific workflow trying to keep up with technology: Accelerating 4D image segmentation applied to nasa data
In 2016, a team of earth scientists directly engaged a team of computer scientists to identify cyberinfrastructure (CI) approaches that would speed up an earth science workflow. This paper describes the evolution of that workflow as the two teams bridged CI and an image segmentation algorithm to do large scale earth science research. The Pacific Research Platform (PRP) and The Cognitive Hardware and Software Ecosystem Community Infrastructure (CHASE-CI) resources were used to significantly decreased the earth science workflow's wall-clock time from 19.5 days to 53 minutes. The improvement in wall-clock time comes from the use of network appliances, improved image segmentation, deployment of a containerized workflow, and the increase in CI experience and training for the earth scientists. This paper presents a description of the evolving innovations used to improve the workflow, bottlenecks identified within each workflow version, and improvements made within each version of the workflow, over a three-year time period
Networks of Recurrent Events, a Theory of Records, and an Application to Finding Causal Signatures in Seismicity
We propose a method to search for signs of causal structure in spatiotemporal
data making minimal a priori assumptions about the underlying dynamics. To this
end, we generalize the elementary concept of recurrence for a point process in
time to recurrent events in space and time. An event is defined to be a
recurrence of any previous event if it is closer to it in space than all the
intervening events. As such, each sequence of recurrences for a given event is
a record breaking process. This definition provides a strictly data driven
technique to search for structure. Defining events to be nodes, and linking
each event to its recurrences, generates a network of recurrent events.
Significant deviations in properties of that network compared to networks
arising from random processes allows one to infer attributes of the causal
dynamics that generate observable correlations in the patterns. We derive
analytically a number of properties for the network of recurrent events
composed by a random process. We extend the theory of records to treat not only
the variable where records happen, but also time as continuous. In this way, we
construct a fully symmetric theory of records leading to a number of new
results. Those analytic results are compared to the properties of a network
synthesized from earthquakes in Southern California. Significant disparities
from the ensemble of acausal networks that can be plausibly attributed to the
causal structure of seismicity are: (1) Invariance of network statistics with
the time span of the events considered, (2) Appearance of a fundamental length
scale for recurrences, independent of the time span of the catalog, which is
consistent with observations of the ``rupture length'', (3) Hierarchy in the
distances and times of subsequent recurrences.Comment: 19 pages, 13 figure
The study of neutron star magnetospheres with LOFT
This is a White Paper in support of the mission concept of the Large
Observatory for X-ray Timing (LOFT), proposed as a medium-sized ESA mission. We
discuss the potential of LOFT for the study of magnetospheres of isolated
neutron stars. For a summary, we refer to the paper.Comment: White Paper in Support of the Mission Concept of the Large
Observatory for X-ray Timin
Observation of an extended VHE gamma-ray emission from MSH 15-52 with CANGAROO-III
We have observed the supernova remnant MSH 15-52 (G320.4-1.2), which contains
the gamma-ray pulsar PSR B1509-58, using the CANGAROO-III imaging atmospheric
Cherenkov telescope array from April to June in 2006. We detected gamma rays
above 810 GeV at the 7 sigma level during a total effective exposure of 48.4
hours. We obtained a differential gamma-ray flux at 2.35 TeV of
(7.9+/-1.5_{stat}+/-1.7_{sys}) \times 10^{-13} cm^{-2}s^{-1}TeV^{-1} with a
photon index of 2.21+/-0.39_{stat}+/-0.40_{sys}, which is compatible with that
of the H.E.S.S. observation in 2004. The morphology shows extended emission
compared to our Point Spread Function. We consider the plausible origin of the
high energy emission based on a multi-wavelength spectral analysis and
energetics arguments.Comment: 9 pages, 9 figures, Accepted in Ap
Automated Synthesis of Tableau Calculi
This paper presents a method for synthesising sound and complete tableau
calculi. Given a specification of the formal semantics of a logic, the method
generates a set of tableau inference rules that can then be used to reason
within the logic. The method guarantees that the generated rules form a
calculus which is sound and constructively complete. If the logic can be shown
to admit finite filtration with respect to a well-defined first-order semantics
then adding a general blocking mechanism provides a terminating tableau
calculus. The process of generating tableau rules can be completely automated
and produces, together with the blocking mechanism, an automated procedure for
generating tableau decision procedures. For illustration we show the
workability of the approach for a description logic with transitive roles and
propositional intuitionistic logic.Comment: 32 page
Gamma-Ray Emissions from Pulsars: Spectra of the TEV Fluxes from Outer-Gap Accelerators
We study the gamma-ray emissions from an outer-magnetospheric potential gap
around a rotating neutron star. Migratory electrons and positrons are
accelerated by the electric field in the gap to radiate copious gamma-rays via
curvature process. Some of these gamma-rays materialize as pairs by colliding
with the X-rays in the gap, leading to a pair production cascade. Imposing the
closure condition that a single pair produces one pair in the gap on average,
we explicitly solve the strength of the acceleration field and demonstrate how
the peak energy and the luminosity of the curvature-radiated, GeV photons
depend on the strength of the surface blackbody and the power-law emissions.
Some predictions on the GeV emission from twelve rotation-powered pulsars are
presented. We further demonstrate that the expected pulsed TeV fluxes are
consistent with their observational upper limits. An implication of high-energy
pulse phase width versus pulsar age, spin, and magnetic moment is discussed.Comment: Revised to compute absolute TeV spectra (22 pages, 9 figures
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