7,819 research outputs found
Effect of parallactic refraction correction on station height determination
The effect of omitting the parallactic refraction correction for satellite optical observations in the determination of station coordinates is analyzed for a large satellite data distribution. A significant error effect is seen in station heights. A geodetic satellite data distribution of 23 close earth satellites, containing 30,000 optical observations obtained by 13 principal Baker-Nunn camera sites, is employed. This distribution was used in a preliminary Goddard Earth Model (GEM 1) for the determination of the gravity field of the earth and geocentric tracking station locations. The parallactic refraction correction is modeled as an error on the above satellite data and a least squares adjustment for station locations is obtained for each of the 13 Baker-Nunn sites. Results show an average station height shift of +8 meters with a dispersion of plus or minus 0.7 meters for individual sites. Station latitude and longitude shifts amounted to less than a meter. Similar results are obtained from a theoretical method employing a probability distribution for the satellite optical observations
The Theory and Principles of War
My theme this morning is stated to be The Theory and Principles of War. I am going to try to consider just a little bit here something of the nature, the types, and the theory of war; something of the interrelationships between the use of force and policy in applying these theories; something as to how these apply to strategic considerations
A Comparison of Predictions for SM Higgs Boson Production at the LHC
This paper describes a comparison of most of the available predictions for
the cross section and transverse momentum distribution for a 125 GeV mass Higgs
at the LHC, including those from the PYTHIA and HERWIG parton shower Monte
Carlos and from four resummation calculations.Comment: 7 pages, submitted to proceedings of the Workshop on Physics at TeV
Colliders, Les Houches 200
Data base management system analysis and performance testing with respect to NASA requirements
Several candidate Data Base Management Systems (DBM's) that could support the NASA End-to-End Data System's Integrated Data Base Management System (IDBMS) Project, later rescoped and renamed the Packet Management System (PMS) were evaluated. The candidate DBMS systems which had to run on the Digital Equipment Corporation VAX 11/780 computer system were ORACLE, SEED and RIM. Oracle and RIM are both based on the relational data base model while SEED employs a CODASYL network approach. A single data base application which managed stratospheric temperature profiles was studied. The primary reasons for using this application were an insufficient volume of available PMS-like data, a mandate to use actual rather than simulated data, and the abundance of available temperature profile data
On Compact Routing for the Internet
While there exist compact routing schemes designed for grids, trees, and
Internet-like topologies that offer routing tables of sizes that scale
logarithmically with the network size, we demonstrate in this paper that in
view of recent results in compact routing research, such logarithmic scaling on
Internet-like topologies is fundamentally impossible in the presence of
topology dynamics or topology-independent (flat) addressing. We use analytic
arguments to show that the number of routing control messages per topology
change cannot scale better than linearly on Internet-like topologies. We also
employ simulations to confirm that logarithmic routing table size scaling gets
broken by topology-independent addressing, a cornerstone of popular
locator-identifier split proposals aiming at improving routing scaling in the
presence of network topology dynamics or host mobility. These pessimistic
findings lead us to the conclusion that a fundamental re-examination of
assumptions behind routing models and abstractions is needed in order to find a
routing architecture that would be able to scale ``indefinitely.''Comment: This is a significantly revised, journal version of cs/050802
Propeller Slipstream Effects As Determined From Wing Pressure Distribution Of A Large-Scale Six-Propeller VTOL Model At Static Thrust
Propeller slipstream effects as determined from wing pressure distribution of a large-scale six-propeller vtol model at static thrus
The high pressure phase transformation behavior of silicon nanowires
Si nanowires of 80–150 nm and 200–250 nm diameter are pressurized up to 22 GPa using a
diamond anvil cell. Raman and x-ray diffraction data were collected during both compression and
decompression. Electron microscopy images reveal that the nanowires retain a nanowire-like morphology
(after high pressure treatment). On compression, dc-Si was observed to persist at pressures
up to 19 GPa compared to 11 GPa for bulk-Si. On decompression, the metallic b-Sn phase was
found to be more stable for Si nanowires compared with bulk-Si when lowering the pressure and
was observed as low as 6 GPa. For the smallest nanowires studied (80–150 nm), predominately a-Si
was obtained on decompression, whereas for larger nanowires (200–250 nm), clear evidence for
the r8/bc8-Si phase was obtained. We suggest that the small volume of the individual Si nanowires
compared with bulk-Si inhibits the nucleation of the r8-Si phase on decompression. This study
shows that there is a size dependence in the high pressure behavior of Si nanowires during both
compression and decompressionL.Q.H. acknowledges her support from an Australian
Government Research Training Program Scholarship. J.E.B.
would like to acknowledge funding from the ARC Future
Fellowship Scheme. A.L. acknowledges financial support
from the Austrian Science Fund (FWF): Project No. P28175-
N27 and e-beam lithography support by Manfred Reiche
from the Max Planck Institute of Microstructure Physics,
Halle, German
kt Effects in Direct-Photon Production
We discuss the phenomenology of initial-state parton-kt broadening in
direct-photon production and related processes in hadron collisions. After a
brief summary of the theoretical basis for a Gaussian-smearing approach, we
present a systematic study of recent results on fixed-target and collider
direct-photon production, using complementary data on diphoton and pion
production to provide empirical guidance on the required amount of kt
broadening. This approach provides a consistent description of the observed
pattern of deviation of next-to-leading order QCD calculations relative to the
direct-photon data, and accounts for the shape and normalization difference
between fixed-order perturbative calculations and the data. We also discuss the
uncertainties in this phenomenological approach, the implications of these
results on the extraction of the gluon distribution of the nucleon, and the
comparison of our findings to recent related work.Comment: LaTeX, uses revtex and epsf, 37 pages, 15 figure
Locations of adenovirus genes required for the replication of adenovirus-associated virus.
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