29,285 research outputs found
Flight evaluation of a hydromechanical backup control for the digital electronic engine control system in an F100 engine
The backup control (BUC) features, the operation of the BUC system, the BUC control logic, and the BUC flight test results are described. The flight test results include: (1) transfers to the BUC at military and maximum power settings; (2) a military power acceleration showing comparisons bvetween flight and simulation for BUC and primary modes; (3) steady-state idle power showing idle compressor speeds at different flight conditions; and (4) idle-to-military power BUC transients showing where cpmpressor stalls occurred for different ramp rates and idle speeds. All the BUC transfers which occur during the DEEC flight program are initiated by the pilot. Automatic transfers to the BUC do not occur
Vapor condensation process produces slurry of magnesium particles in liquid hydrocarbons
Vapor condensation apparatus produces a physically stable, homogeneous slurry of finely divided magnesium and liquid hydrocarbons. The magnesium is vaporized and the resultant vapor is cooled rapidly with a liquid hydrocarbon spray, which also serves as the dispersing medium for the condensed magnesium particles
Apparatus for making a metal slurry product Patent
Apparatus for producing hydrocarbon slurry containing small particles of magnesium for use as jet aircraft fue
Using HINODE/Extreme-Ultraviolet Imaging Spectrometer to confirm a seismologically inferred coronal temperature
The Extreme-Ultraviolet Imaging Spectrometer on board the HINODE satellite is used to examine the loop system described in Marsh et al. (2009) by applying spectroscopic diagnostic methods. A simple isothermal mapping algorithm is applied to determine where the assumption of isothermal plasma may be valid, and the emission measure locii technique is used to determine the temperature profile along the base of the loop system. It is found that, along the base, the loop has a uniform temperature profile with a mean temperature of 0.89 +- 0.09 MK which is in agreement with the temperature determined seismologically in Marsh et al. (2009), using observations interpreted as the slow magnetoacoustic mode. The results further strengthen the slow mode interpretation, propagation at a uniform sound speed, and the analysis method applied in Marsh et al. (2009). It is found that it is not possible to discriminate between the slow mode phase speed and the sound speed within the precision of the present observations
Factorization and Resummation for Dijet Invariant Mass Spectra
Multijet cross sections at the LHC and Tevatron are sensitive to several
distinct kinematic energy scales. When measuring the dijet invariant mass m_jj
between two signal jets produced in association with other jets or weak bosons,
m_jj will typically be much smaller than the total partonic center-of-mass
energy Q, but larger than the individual jet masses m, such that there can be a
hierarchy of scales m << m_jj << Q. This situation arises in many new-physics
analyses at the LHC, where the invariant mass between jets is used to gain
access to the masses of new-physics particles in a decay chain. At present, the
logarithms arising from such a hierarchy of kinematic scales can only be summed
at the leading-logarithmic level provided by parton-shower programs. We
construct an effective field theory, SCET+, which is an extension of
soft-collinear effective theory that applies to this situation of hierarchical
jets. It allows for a rigorous separation of different scales in a multiscale
soft function and for a systematic resummation of logarithms of both m_jj/Q and
m/Q. As an explicit example, we consider the invariant mass spectrum of the two
closest jets in e+e- -> 3 jets. We also give the generalization to pp -> N jets
plus leptons relevant for the LHC.Comment: 37 pages, 6 figures; v2: journal versio
The time resolved measurement of ultrashort THz-band electric fields without an ultrashort probe
The time-resolved detection of ultrashort pulsed THz-band electric field
temporal profiles without an ultrashort laser probe is demonstrated. A
non-linear interaction between a narrow-bandwidth optical probe and the THz
pulse transposes the THz spectral intensity and phase information to the
optical region, thereby generating an optical pulse whose temporal electric
field envelope replicates the temporal profile of the real THz electric field.
This optical envelope is characterised via an autocorrelation based FROG
measurement, hence revealing the THz temporal profile. The combination of a
narrow-bandwidth, long duration, optical probe and self-referenced FROG makes
the technique inherently immune to timing jitter between the optical probe and
THz pulse, and may find particular application where the THz field is not
initially generated via ultrashort laser methods, such as the measurement of
longitudinal electron bunch profiles in particle accelerators.Comment: 7 pages, 3 figures, submitted to AP
Jet p_T Resummation in Higgs Production at NNLL'+NNLO
We present predictions for Higgs production via gluon fusion with a p_T veto
on jets and with the resummation of jet-veto logarithms at NNLL'+$NNLO order.
These results incorporate explicit O(alphas^2) calculations of soft and beam
functions, which include the dominant dependence on the jet radius R. In
particular the NNLL' order accounts for the correct boundary conditions for the
N3LL resummation, for which the only unknown ingredients are higher-order
anomalous dimensions. We use scale variations in a factorization theorem in
both rapidity and virtuality space to estimate the perturbative uncertainties,
accounting for both higher fixed-order corrections as well as higher-order
towers of jet-p_T logarithms. This formalism also predicts the correlations in
the theory uncertainty between the exclusive 0-jet and inclusive 1-jet bins. At
the values of R used experimentally, there are important corrections due to jet
algorithm clustering that include logarithms of R. Although we do not sum
logarithms of R, we do include an explicit contribution in our uncertainty
estimate to account for higher-order jet clustering logarithms. Precision
predictions for this H+0-jet cross section and its theoretical uncertainty are
an integral part of Higgs analyses that employ jet binning.Comment: 24 pages, 11 figure
Instrumentation for measurement of cosmic noise at 750, 1225, and 2000 kHz from a rocket Final technical report
Design and performance characteristics of rocketborne instrumentation system to measure radio frequency noise energ
Drell-Yan Production at NNLL'+NNLO Matched to Parton Showers
We present results for Drell-Yan production from the GENEVA Monte-Carlo
framework. We combine the fully-differential NNLO calculation with higher-order
resummation in the 0-jettiness resolution variable. The resulting parton-level
events are further combined with parton showering and hadronization provided by
PYTHIA8. The 0-jettiness resummation is carried out to NNLL', which
consistently incorporates all singular virtual and real NNLO corrections. It
thus provides a natural perturbative connection between the NNLO calculation
and the parton shower regime, including a systematic assessment of perturbative
uncertainties. In this way, inclusive observables are correct to NNLO, up to
small power corrections in the resolution cutoff. Furthermore, the perturbative
accuracy of 0-jet-like resummation variables is significantly improved beyond
the parton shower approximation. We provide comparisons with LHC measurements
of Drell-Yan production at 7 TeV from ATLAS, CMS, and LHCb. As already observed
in collisions, for resummation-sensitive observables, the agreement
with data is noticeably improved by using a lower value of .Comment: 26 pages, 20 figure
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