6,446 research outputs found
Solid state switch provides high input-to-output isolation
Switch uses a combination of N-channel and P-channel Metal Oxide Semiconductor Field Effect Transistors /MOSFET/ to obtain a normally open switch with no power applied. Series-shunt-series MOSFET switching achieves high input-output isolation
Allocating Awards Across Noncomparable Categories
Suppose an agency awards a …xed number of prizes to applicants in different categories such that the applicant-to-winner ratio is constant by category. It is demonstrated in a simple theoretical model that the number of awards in a category will typically be positively related to the degree of applicant uncertainty. The theoretical …ndings are related to awards data from the Social Sciences and Humanities Research Council of Canada doctoral fellowship competition.
Wind tunnel test on a 1/4.622 Froude scale, hingeless rotor, tilt rotor model, volume 1
Wing tunnel test data on a 1/4.622 Froude scale, hingeless rotor, tilt rotor mode are reported for all potential flight conditions through hover and a wide envelope of transitions. A mathematical model was used to describe the rotor system in real time simulation by means of regression analyses. Details of the model, test program and data system are provided together with four data files for hover and transition
The investigation of flame spreading over the surface of igniting solid propellants Final summary report
Flame spreading over surface of igniting solid propellants in different gas mixtures at various pressure
Conceptual design studies of 1985 commercial VTOL transports that utilized rotors, Volume 2
Results of conceptual design studies of tilt rotor and tandem helicopter aircraft for a 200 nautical mile commercial short haul transport mission are presented. The trade study data used in selecting the design point aircraft and technology details necessary to support the design conclusions are included
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Epeiric Depositional Models for the Lower Cretaceous Washita Group North-Central Texas
UT Librarie
Adhesive coating eliminated in new honeycomb-core fabrication process
Technique eliminates use of silicone-based adhesive material as bonding medium. Adhesive requires precise time-temperature cure. Prepreg resin is used as bonding medium, and each layer is laminated together to form honeycomb billet. Process can be used in any application where nonmetallic honeycomb core is being fabricated
Swashplate feedback control for tilt-rotor aircraft
Changes in angle of attack in system were sensed indirectly by gages which responded to strains induced in wing structure. Output signals were amplified, filtered, and used to activate swashplate actuators. System provided significant reduction in blade loads and desirable changes in hub forces and moments
Detecting the signatures of helium in type Iax supernovae
Recent studies have argued that the progenitor system of type Iax supernovae
must consist of a carbon-oxygen white dwarf accreting from a helium star
companion. Based on existing explosion models invoking the pure deflagration of
carbon-oxygen white dwarfs, we investigate the likelihood of producing spectral
features due to helium in type Iax supernovae. From this scenario, we select
those explosion models producing ejecta and Ni masses that are broadly
consistent with those estimated for type Iax supernovae (0.014 -
0.478~ and - 0.183~, respectively). To this
end, we present a series of models of varying luminosities (~mag) with helium abundances accounting for up to
36\% of the ejecta mass, and covering a range of epochs beginning a few
days before Bband maximum to approximately two weeks after maximum. We find
that the best opportunity for detecting \ion{He}{i} features is at
near-infrared wavelengths, and in the post-maximum spectra of the fainter
members of this class. We show that the optical spectrum of SN~2007J is
potentially consistent with a large helium content (a few 10),
but argue that current models of accretion and material stripping from a
companion struggle to produce compatible scenarios. We also investigate the
presence of helium in all objects with near-infrared spectra. We show that
SNe~2005hk, 2012Z, and 2015H contain either no helium or their helium
abundances are constrained to much lower values
(10). Our results demonstrate the differences in
helium content among type Iax supernovae, perhaps pointing to different
progenitor channels. Either SN~2007J is an outlier in terms of its progenitor
system, or it is not a true member of the type Iax supernova class.Comment: 15 pages, 12 figures, 2 tables. Accepted for publication in Astronomy
and Astrophysic
Fluent temporal logic for discrete-time event-based models
Fluent model checking is an automated technique for verifying that an event-based operational model satisfies some state-based declarative properties. The link between the event-based and state-based formalisms is defined through fluents which are state predicates whose value are determined by the occurrences of initiating and terminating events that make the fluents values become true or false, respectively. The existing fluent temporal logic is convenient for reasoning about untimed event-based models but difficult to use for timed models. The paper extends fluent temporal logic with temporal operators for modelling timed properties of discrete-time event-based models. It presents two approaches that differ on whether the properties model the system state after the occurrence of each event or at a fixed time rate. Model checking of timed properties is made possible by translating them into the existing untimed framework. Copyright 2005 ACM
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