9,074 research outputs found
Global-Scale Resource Survey and Performance Monitoring of Public OGC Web Map Services
One of the most widely-implemented service standards provided by the Open
Geospatial Consortium (OGC) to the user community is the Web Map Service (WMS).
WMS is widely employed globally, but there is limited knowledge of the global
distribution, adoption status or the service quality of these online WMS
resources. To fill this void, we investigated global WMSs resources and
performed distributed performance monitoring of these services. This paper
explicates a distributed monitoring framework that was used to monitor 46,296
WMSs continuously for over one year and a crawling method to discover these
WMSs. We analyzed server locations, provider types, themes, the spatiotemporal
coverage of map layers and the service versions for 41,703 valid WMSs.
Furthermore, we appraised the stability and performance of basic operations for
1210 selected WMSs (i.e., GetCapabilities and GetMap). We discuss the major
reasons for request errors and performance issues, as well as the relationship
between service response times and the spatiotemporal distribution of client
monitoring sites. This paper will help service providers, end users and
developers of standards to grasp the status of global WMS resources, as well as
to understand the adoption status of OGC standards. The conclusions drawn in
this paper can benefit geospatial resource discovery, service performance
evaluation and guide service performance improvements.Comment: 24 pages; 15 figure
IceCube: physics, status, and future
The IceCube observatory is the first cubic kilometre scale instrument in the
field of high-energy neutrino astronomy and cosmic rays. In 2009, following
five successful deployment seasons, IceCube consisted of 59 strings of optical
modules in the South Pole ice, together with 118 air shower detectors in the
IceTop surface array. The range of physics topics includes neutrino signals
from astrophysical sources, dark matter, exotic particle physics, cosmic rays,
and atmospheric neutrinos. The current IceCube status and selected results are
described. Anticipated future developments are also discussed, in particular
the Deep Core low energy subarray which was recently deployed.Comment: Presentation at the 4th International Workshop on Very Large Volume
Neutrino Telescope
Dynamics of midlatitude light ion trough and plasmatails
Light ion trough measurements near midnight made by the RF ion mass spectrometer on OGO-4 operating in the high resolution mode in Feb. 1968 reveal the existence of irregular structure on the low latitude side of the midlatitude trough. Using two different relations between the equatorial convection electric field, assumed spatially invariant and directed from dawn to dusk, and Kp (one based on plasmapause measurements, the other on polar cap E field measurements) a model development was made of the outer plasmasphere. The model calculations produced multiple plasmatail extensions of the plasmasphere which compare favorably with the observed irregularities. Due to magnetic local time differences between the Northern and Southern Hemisphere along OGO's orbit, the time dependent irregularity structure observed is not symmetrical about the equator. The model development produces an outer plasmasphere boundary location which varies similarly to the observed minimum density point of the light ion trough. However the measurements are not extensive enough to yield conclusive proof that one of the electric field models is better than the other
On Level One Cuspidal Bianchi Modular Forms
In this paper, we present the outcome of vast computer calculations, locating
several of the very rare instances of level one cuspidal Bianchi modular forms
that are not lifts of elliptic modular forms.Comment: final versio
Digital overlaying of the universal transverse Mercator grid with LANDSAT data derived products
Picture elements of data from the LANDSAT multispectral scanner are correlated with the universal tranverse Mercator grid. In the procedure, a series of computer modules was used to make approximations of universal transverse Mercator grid locations for all picture elements from the grid locations of a limited number of known control points and to provide display and digital storage of the data. The software has been written in FORTRAN 4 language for a Varian 70-series computer
Semiannual Status Report, 1 July 1975 Through 31 December 1975
No abstract availabl
Jets from Massive Unstable Particles: Top-Mass Determination
We construct jet observables for energetic top quarks that can be used to
determine a short distance top quark mass from reconstruction in e+ e-
collisions with accuracy better than Lambda_{QCD}. Using a sequence of
effective field theories we connect the production energy, mass, and top width
scales, Q>> m>> Gamma, for the top jet cross section, and derive a QCD
factorization theorem for the top invariant mass spectrum. Our analysis
accounts for: alpha_s corrections from the production and mass scales,
corrections due to constraints in defining invariant masses, non-perturbative
corrections from the cross-talk between the jets, and alpha_s corrections to
the Breit-Wigner line-shape. This paper mainly focuses on deriving the
factorization theorem for hemisphere invariant mass distributions and other
event shapes in e+e- collisions applicable at a future Linear Collider. We show
that the invariant mass distribution is not a simple Breit-Wigner involving the
top width. Even at leading order it is shifted and broadened by
non-perturbative soft QCD effects. We predict that the invariant mass peak
position increases linearly with Q/m due to these non-perturbative effects.
They are encoded in terms of a universal soft function that also describes soft
effects for massless dijet events. In a future paper we compute alpha_s
corrections to the jet invariant mass spectrum, including a summation of large
logarithms between the scales Q, m and Gamma.Comment: 54 pages, 10 figures, typos corrected, figures update
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