7,716 research outputs found
Digital electronic engine control fault detection and accommodation flight evaluation
The capabilities and performance of various fault detection and accommodation (FDA) schemes in existing and projected engine control systems were investigated. Flight tests of the digital electronic engine control (DEEC) in an F-15 aircraft show discrepancies between flight results and predictions based on simulation and altitude testing. The FDA methodology and logic in the DEEC system, and the results of the flight failures which occurred to date are described
Early search for supersymmetric dark matter models at the LHC without missing energy
We investigate early discovery signals for supersymmetry at the Large Hadron
Collider without using information about missing transverse energy. Instead we
use cuts on the number of jets and isolated leptons (electrons and/or muons).
We work with minimal supersymmetric extensions of the standard model, and focus
on phenomenological models that give a relic density of dark matter compatible
with the WMAP measurements. An important model property for early discovery is
the presence of light sleptons, and we find that for an integrated luminosity
of only 200--300 pb at a center-of-mass energy of 10 TeV models with
gluino masses up to GeV can be tested.Comment: 28 pages, 12 figures; published versio
Probing Neutralino Resonance Annihilation via Indirect Detection of Dark Matter
The lightest neutralino of R-parity conserving supersymmetric models serves
as a compelling candidate to account for the presence of cold dark matter in
the universe. In the minimal supergravity (mSUGRA) model, a relic density can
be found in accord with recent WMAP data for large values of the parameter
, where neutralino annihilation in the early universe occurs via the
broad s-channel resonance of the pseudoscalar Higgs boson . We map out rates
for indirect detection of neutralinos via 1. detection of neutrinos arising
from neutralino annihilation in the core of the earth or sun and 2. detection
of gamma rays, antiprotons and positrons arising from neutralino annihilation
in the galactic halo. If indeed -resonance annihilation is the main sink for
neutralinos in the early universe, then signals may occur in the gamma ray,
antiproton and positron channels, while a signal in the neutrino channel would
likely be absent. This is in contrast to the hyperbolic branch/focus point
(HB/FP) region where {\it all} indirect detection signals are likely to occur,
and also in contrast to the stau co-annihilation region, where {\it none} of
the indirect signals are likely to occur.Comment: 12 pages including 4 eps figure
Highly integrated digital electronic control: Digital flight control, aircraft model identification, and adaptive engine control
The highly integrated digital electronic control (HIDEC) program at NASA Ames Research Center, Dryden Flight Research Facility is a multiphase flight research program to quantify the benefits of promising integrated control systems. McDonnell Aircraft Company is the prime contractor, with United Technologies Pratt and Whitney Aircraft, and Lear Siegler Incorporated as major subcontractors. The NASA F-15A testbed aircraft was modified by the HIDEC program by installing a digital electronic flight control system (DEFCS) and replacing the standard F100 (Arab 3) engines with F100 engine model derivative (EMD) engines equipped with digital electronic engine controls (DEEC), and integrating the DEEC's and DEFCS. The modified aircraft provides the capability for testing many integrated control modes involving the flight controls, engine controls, and inlet controls. This paper focuses on the first two phases of the HIDEC program, which are the digital flight control system/aircraft model identification (DEFCS/AMI) phase and the adaptive engine control system (ADECS) phase
Probing Slepton Mass Non-Universality at e^+e^- Linear Colliders
There are many models with non-universal soft SUSY breaking sfermion mass
parameters at the grand unification scale. Even in the mSUGRA model scalar mass
unification might occur at a scale closer to M_Planck, and renormalization
effects would cause a mass splitting at M_GUT. We identify an experimentally
measurable quantity Delta that correlates strongly with delta m^2 =
m^2_{selectron_R}(M_GUT) - m^2_{selectron_L}(M_GUT), and which can be measured
at electron-positron colliders provided both selectrons and the chargino are
kinematically accessible. We show that if these sparticle masses can be
measured with a precision of 1% at a 500 GeV linear collider, the resulting
precision in the determination of Delta may allow experiments to distinguish
between scalar mass unification at the GUT scale from the corresponding
unification at Q ~ M_Planck. Experimental determination of Delta would also
provide a distinction between the mSUGRA model and the recently proposed
gaugino-mediation model. Moreover, a measurement of Delta (or a related
quantity Delta') would allow for a direct determination of delta m^2.Comment: 15 pages, RevTeX, 4 postscript figure
Impact of Muon Anomalous Magnetic Moment on Supersymmetric Models
The recent measurement of a_\mu =\frac{g_\mu -2}{2} by the E821 Collaboration
at Brookhaven deviates from the quoted Standard Model (SM) central value
prediction by 2.6\sigma. The difference between SM theory and experiment may be
easily accounted for in a variety of particle physics models employing weak
scale supersymmetry (SUSY). Other supersymmetric models are distinctly
disfavored. We evaluate a_\mu for various supersymmetric models, including
minimal supergravity (mSUGRA), Yukawa unified SO(10) SUSY GUTs, models with
inverted mass hierarchies (IMH), models with non-universal gaugino masses,
gauge mediated SUSY breaking models (GMSB), anomaly-mediated SUSY breaking
models (AMSB) and models with gaugino mediated SUSY breaking (inoMSB). Models
with Yukawa coupling unification or multi-TeV first and second generation
scalars are disfavored by the a_\mu measurement.Comment: 25 page REVTEX file with 10 PS figures. Minor rewording, typos
corrected, references adde
Fault detection and accommodation testing on an F100 engine in an F-15 airplane
The fault detection and accommodation (FDA) methodology for digital engine-control systems may range from simple comparisons of redundant parameters to the more complex and sophisticated observer models of the entire engine system. Evaluations of the various FDA schemes are done using analytical methods, simulation, and limited-altitude-facility testing. Flight testing of the FDA logic has been minimal because of the difficulty of inducing realistic faults in flight. A flight program was conducted to evaluate the fault detection and accommodation capability of a digital electronic engine control in an F-15 aircraft. The objective of the flight program was to induce selected faults and evaluate the resulting actions of the digital engine controller. Comparisons were made between the flight results and predictions. Several anomalies were found in flight and during the ground test. Simulation results showed that the inducement of dual pressure failures was not feasible since the FDA logic was not designed to accommodate these types of failures
Trilepton Signature of Minimal Supergravity at the Upgraded Tevatron
The prospects for detecting trilepton events ( or ) from
chargino-neutralino () associated production are
investigated for the upgraded Fermilab Tevatron Collider in the context of the
minimal supergravity model (mSUGRA). In some regions of parameter space,
and decay dominantly into final states with
leptons and the contributions from leptonic decays enhance the trilepton
signal substantially when soft cuts on lepton transverse momenta are used.
Additional sources of the mSUGRA trilepton signal and dominant irreducible
backgrounds are discussed. The dilepton () invariant mass
distribution near the endpoint is considered as a test of mSUGRA mass
relations. Discovery contours for at 2 TeV with an
integrated luminosity of 2 fb to 30 fb are presented in the
mSUGRA parameter space of for several choices of .Comment: Version to appear in Physical Review
Prospects for Supersymmetry at LEP2
Working within the framework of the minimal supergravity model with gauge
coupling unification and radiative electroweak symmetry breaking (SUGRA), we
map out regions of parameter space explorable by experiments at LEP2, for
center of mass energy options of , and 205 GeV. We
compute signals from all accessible SUSY pair production
processes using the ISAJET simulation program, and devise cuts that enhance the
signal relative to Standard Model backgrounds, and which also serve to
differentiate various supersymmetric processes from one another. We delineate
regions of SUGRA parameter space where production of neutralino pairs, chargino
pairs, slepton pairs and the production of the light Higgs scalar of SUSY is
detectable above Standard Model backgrounds and distinguishable from other SUSY
processes. In addition, we find small regions of SUGRA parameter space where
\te\te, \tz_2\tz_2 and \tnu_L\tnu_L production yields spectacular events
with up to four isolated leptons. The combined regions of parameter space
explorable by LEP2 are compared with the reach of Tevatron Main Injector era
experiments. Finally, we comment on how the reach via the neutralino pair
channel is altered when the radiative electroweak symmetry breaking constraint
is relaxed.Comment: 22 page REVTEX file + 9 uuencoded figures; a uuencoded PS file with
PS figures is available via anonymous ftp at
ftp://hep.fsu.edu/preprints/baer/FSUHEP950501.u
SIGNALS FOR MINIMAL SUPERGRAVITY AT THE CERN LARGE HADRON COLLIDER: MULTI-JET PLUS MISSING ENERGY CHANNEL,
We use ISAJET to perform a detailed study of the missing transverse energy
\eslt plus multi-jet signal expected from superparticle production at the
CERN LHC. Our analysis is performed within the framework of the minimal
supergravity model with gauge coupling unification and radiative electroweak
symmetry breaking. We delineate the region of parameter space where the \eslt
supersymmetry signal should be observable at the LHC and compare it to the
regions explorable via searches for sleptons and for chargino/neutralino
production. We confirm that, given a data sample of 10~\fb^{-1}, GeV can be explored if m_{\tq}\gg m_{\tg}, while GeV
can be probed if m_{\tq}\simeq m_{\tg}. We further examine what information
can be gleaned from scrutinizing this event sample. For instance, the multi-jet
multiplicity yields information on whether squark production makes a
significant contribution to the observed \eslt sample. Furthermore,
reconstructing hemispheric masses may yield a measure of to . Finally, for favourable ranges of parameters, by reconstructing
masses of tagged jet pairs, it may be possible to detect Higgs
bosons produced via sparticle cascade decay chains.Comment: 22 pages (REVTEX); a PS text file (etmiss.ps) and 12 figures
(etlhc.uu or etlhc.ps) can be obtained via anonymous ftp at
ftp://hep.fsu.edu/anonymous.bae
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