52,165 research outputs found
Inverter ratio failure detector
A failure detector which detects the failure of a dc to ac inverter is disclosed. The inverter under failureless conditions is characterized by a known linear relationship of its input and output voltages and by a known linear relationship of its input and output currents. The detector includes circuitry which is responsive to the detector's input and output voltages and which provides a failure-indicating signal only when the monitored output voltage is less by a selected factor, than the expected output voltage for the monitored input voltage, based on the known voltages' relationship. Similarly, the detector includes circuitry which is responsive to the input and output currents and provides a failure-indicating signal only when the input current exceeds by a selected factor the expected input current for the monitored output current based on the known currents' relationship
Advanced gearbox technology
An advanced 13,000 HP, counterrotating (CR) gearbox was designed and successfully tested to provide a technology base for future designs of geared propfan propulsion systems for both commercial and military aircraft. The advanced technology CR gearbox was designed for high efficiency, low weight, long life, and improved maintainability. The differential planetary CR gearbox features double helical gears, double row cylindrical roller bearings integral with planet gears, tapered roller prop support bearings, and a flexible ring gear and diaphragm to provide load sharing. A new Allison propfan back-to-back gearbox test facility was constructed. Extensive rotating and stationary instrumentation was used to measure temperature, strain, vibration, deflection and efficiency under representative flight operating conditions. The tests verified smooth, efficient gearbox operation. The highly-instrumented advanced CR gearbox was successfully tested to design speed and power (13,000 HP), and to a 115 percent overspeed condition. Measured CR gearbox efficiency was 99.3 percent at the design point based on heat loss to the oil. Tests demonstrated low vibration characteristics of double helical gearing, proper gear tooth load sharing, low stress levels, and the high load capacity of the prop tapered roller bearings. Applied external prop loads did not significantly affect gearbox temperature, vibration, or stress levels. Gearbox hardware was in excellent condition after the tests with no indication of distress
SUSY-Breaking Parameters from RG Invariants at the LHC
We study Renormalization Group invariant (RGI) quantities in the Minimal
Supersymmetric Standard Model and show that they are a powerful and simple
instrument for testing high scale models of supersymmetry (SUSY)-breaking. For
illustration, we analyze the frameworks of minimal and general gauge mediated
(MGM and GGM) SUSY-breaking, with additional arbitrary soft Higgs mass
parameters at the messenger scale. We show that if a gaugino and two first
generation sfermion soft masses are determined at the LHC, the RGIs lead to MGM
sum rules that yield accurate predictions for the other gaugino and first
generation soft masses. RGIs can also be used to reconstruct the fundamental
MGM parameters (including the messenger scale), calculate the hypercharge
D-term, and find relationships among the third generation and Higgs soft
masses. We then study the extent to which measurements of the full first
generation spectrum at the LHC may distinguish different SUSY-breaking
scenarios. In the case of MGM, although most deviations violate the sum rules
by more than estimated experimental errors, we find a 1-parameter family of GGM
models that satisfy the constraints and produce the same first generation
spectrum. The GGM-MGM degeneracy is lifted by differences in the third
generation masses and the messenger scales.Comment: (v1) 30 pages; (v2) mislabeling in figs 2 and 3 corrected, version
accepted for publication in Phys. Rev.
Determining the Structure of Supersymmetry-Breaking with Renormalization Group Invariants
If collider experiments demonstrate that the Minimal Supersymmetric Standard
Model (MSSM) is a good description of nature at the weak scale, the
experimental priority will be the precise determination of superpartner masses.
These masses are governed by the weak scale values of the soft supersymmetry
(SUSY)-breaking parameters, which are in turn highly dependent on the
SUSY-breaking scheme present at high scales. It is therefore of great interest
to find patterns in the soft parameters that can distinguish different high
scale SUSY-breaking structures, identify the scale at which the breaking is
communicated to the visible sector, and determine the soft breaking parameters
at that scale. In this work, we demonstrate that 1-loop Renormalization
Group~(RG) invariant quantities present in the MSSM may be used to answer each
of these questions. We apply our method first to generic flavor-blind models of
SUSY-breaking, and then examine in detail the subset of these models described
by General Gauge Mediation and the constrained MSSM with non-universal Higgs
masses. As RG invariance generally does not hold beyond leading-log order, we
investigate the magnitude and direction of the 2-loop corrections. We find that
with superpartners at the TeV scale, these 2-loop effects are either
negligible, or they are of the order of optimistic experimental uncertainties
and have definite signs, which allows them to be easily accounted for in the
overall uncertainty.Comment: v2 -- references added, version to be published in PRD; 40 page
Gravity model improvement using GEOS-3 (GEM 9 and 10)
The use of collocation permitted GEM 9 to be a larger field than previous derived satellite models, GEM 9 having harmonics complete to 20 x 20 with selected higher degree terms. The satellite data set has approximately 840,000 observations, of which 200,000 are laser ranges taken on 9 satellites equipped with retroreflectors. GEM 10 is complete to 22 x 22 with selected higher degree terms out to degree and order 30 amounting to a total of 592 coefficients. Comparisons with surface gravity and altimeter data indicate a substantial improvement in GEM 9 over previous satellite solutions; GEM 9 is in even closer agreement with surface data than the previously published GEM 6 solution which contained surface gravity. In particular the free air gravity anomalies calculated from GEM 9 and a surface gravity solution are in excellent agreement for the high degree terms
The future of Earth observation in hydrology
In just the past 5 years, the field of Earth observation has progressed beyond the offerings of conventional space-agency-based platforms to include a plethora of sensing opportunities afforded by CubeSats, unmanned aerial vehicles (UAVs), and smartphone technologies that are being embraced by both for-profit companies and individual researchers. Over the previous decades, space agency efforts have brought forth well-known and immensely useful satellites such as the Landsat series and the Gravity Research and Climate Experiment (GRACE) system, with costs typically of the order of 1 billion dollars per satellite and with concept-to-launch timelines of the order of 2 decades (for new missions). More recently, the proliferation of smart-phones has helped to miniaturize sensors and energy requirements, facilitating advances in the use of CubeSats that can be launched by the dozens, while providing ultra-high (3-5 m) resolution sensing of the Earth on a daily basis. Start-up companies that did not exist a decade ago now operate more satellites in orbit than any space agency, and at costs that are a mere fraction of traditional satellite missions. With these advances come new space-borne measurements, such as real-time high-definition video for tracking air pollution, storm-cell development, flood propagation, precipitation monitoring, or even for constructing digital surfaces using structure-from-motion techniques. Closer to the surface, measurements from small unmanned drones and tethered balloons have mapped snow depths, floods, and estimated evaporation at sub-metre resolutions, pushing back on spatio-temporal constraints and delivering new process insights. At ground level, precipitation has been measured using signal attenuation between antennae mounted on cell phone towers, while the proliferation of mobile devices has enabled citizen scientists to catalogue photos of environmental conditions, estimate daily average temperatures from battery state, and sense other hydrologically important variables such as channel depths using commercially available wireless devices. Global internet access is being pursued via high-altitude balloons, solar planes, and hundreds of planned satellite launches, providing a means to exploit the "internet of things" as an entirely new measurement domain. Such global access will enable real-time collection of data from billions of smartphones or from remote research platforms. This future will produce petabytes of data that can only be accessed via cloud storage and will require new analytical approaches to interpret. The extent to which today's hydrologic models can usefully ingest such massive data volumes is unclear. Nor is it clear whether this deluge of data will be usefully exploited, either because the measurements are superfluous, inconsistent, not accurate enough, or simply because we lack the capacity to process and analyse them. What is apparent is that the tools and techniques afforded by this array of novel and game-changing sensing platforms present our community with a unique opportunity to develop new insights that advance fundamental aspects of the hydrological sciences. To accomplish this will require more than just an application of the technology: in some cases, it will demand a radical rethink on how we utilize and exploit these new observing systems
Dilaton-Axion hair for slowly rotating Kerr black holes
Campbell et al. demonstrated the existence of axion ``hair'' for Kerr black
holes due to the non-trivial Lorentz Chern-Simons term and calculated it
explicitly for the case of slow rotation. Here we consider the dilaton coupling
to the axion field strength, consistent with low energy string theory and
calculate the dilaton ``hair'' arising from this specific axion source.Comment: 13 pages + 1 fi
Slip-controlled thin film dynamics
In this study, we present a novel method to assess the slip length and the
viscosity of thin films of highly viscous Newtonian liquids. We quantitatively
analyse dewetting fronts of low molecular weight polystyrene melts on
Octadecyl- (OTS) and Dodecyltrichlorosilane (DTS) polymer brushes. Using a thin
film (lubrication) model derived in the limit of large slip lengths, we can
extract slip length and viscosity. We study polymer films with thicknesses
between 50 nm and 230 nm and various temperatures above the glass transition.
We find slip lengths from 100 nm up to 1 micron on OTS and between 300 nm and
10 microns on DTS covered silicon wafers. The slip length decreases with
temperature. The obtained values for the viscosity are consistent with
independent measurements.Comment: 4 figure
The pMSSM Interpretation of LHC Results Using Rernormalization Group Invariants
The LHC has started to constrain supersymmetry-breaking parameters by setting
bounds on possible colored particles at the weak scale. Moreover, constraints
from Higgs physics, flavor physics, the anomalous magnetic moment of the muon,
as well as from searches at LEP and the Tevatron have set additional bounds on
these parameters. Renormalization Group Invariants (RGIs) provide a very useful
way of representing the allowed parameter space by making direct connection
with the values of these parameters at the messenger scale. Using a general
approach, based on the pMSSM parametrization of the soft supersymmetry-breaking
parameters, we analyze the current experimental constraints to determine the
probability distributions for the RGIs. As examples of their application, we
use these distributions to analyze the question of Gaugino Mass Unification and
to probabilistically determine the parameters of General and Minimal Gauge
Mediation with arbitrary Higgs mass parameters at the Messenger Scale.Comment: 38 pages, 10 figure
Teegi: Tangible EEG Interface
We introduce Teegi, a Tangible ElectroEncephaloGraphy (EEG) Interface that
enables novice users to get to know more about something as complex as brain
signals, in an easy, en- gaging and informative way. To this end, we have
designed a new system based on a unique combination of spatial aug- mented
reality, tangible interaction and real-time neurotech- nologies. With Teegi, a
user can visualize and analyze his or her own brain activity in real-time, on a
tangible character that can be easily manipulated, and with which it is
possible to interact. An exploration study has shown that interacting with
Teegi seems to be easy, motivating, reliable and infor- mative. Overall, this
suggests that Teegi is a promising and relevant training and mediation tool for
the general public.Comment: to appear in UIST-ACM User Interface Software and Technology
Symposium, Oct 2014, Honolulu, United State
- …