42,697 research outputs found
Dynamic analysis using superelements for a large helicopter model
Using superelements (substructures), modal and frequency response analysis was performed for a large model of the Advanced Attack Helicopter developed for the U.S. Army. Whiffletree concept was employed so that the residual structure along with the various superelements could be represented as beam-like structures for economical and accurate dynamic analysis. A very large DMAP alter to the rigid format was developed so that the modal analysis, the frequency response, and the strain energy in each component could be computed in the same run
Fault Testing for Reversible Circuits
Applications of reversible circuits can be found in the fields of low-power
computation, cryptography, communications, digital signal processing, and the
emerging field of quantum computation. Furthermore, prototype circuits for
low-power applications are already being fabricated in CMOS. Regardless of the
eventual technology adopted, testing is sure to be an important component in
any robust implementation.
We consider the test set generation problem. Reversibility affects the
testing problem in fundamental ways, making it significantly simpler than for
the irreversible case. For example, we show that any test set that detects all
single stuck-at faults in a reversible circuit also detects all multiple
stuck-at faults. We present efficient test set constructions for the standard
stuck-at fault model as well as the usually intractable cell-fault model. We
also give a practical test set generation algorithm, based on an integer linear
programming formulation, that yields test sets approximately half the size of
those produced by conventional ATPG.Comment: 30 pages, 8 figures. to appear in IEEE Trans. on CA
Same storm, different boats: can the UK recapture improving life expectancy trends?
The COVID-19 pandemic has led to devastating loss of life and livelihood across the world. It has resulted in falls in life expectancy, a widely used summary measure of contemporary age-specific mortality rates, in most European countries.1 In England and Wales, life expectancy has fallen by 0.9 and 1.2 years for women and men, respectively, when compared to 2019.2 These falls are, however, part of a longer-term trend that began long before the COVID-19 pandemic. For the past decade, life expectancy in the UK has been stalling, and falling in some regions and social groups, and inequality in age at death has been rising.3 In this piece, we consider the health of the UK population before the pandemic, compare this to the health of the populations in the USA and Japan, as investigated in a recent paper,3 and ask if it is possible to recapture previous improving life expectancy trajectories
Symptomatic adrenal insufficiency during inhaled corticosteroid treatment
Symptomatic adrenal insufficiency, presenting
as hypoglycaemia or poor weight
gain, may occur on withdrawal of corticosteroid
treatment but has not previously
been reported during inhaled corticosteroid
treatment. This case series illustrates
the occurence of clinically
significant adrenal insufficiency in asthmatic
children while patients were on
inhaled corticosteroid treatment and the
unexpected modes of presentation. General
practitioners and paediatricians need
to be aware that this unusual but acute
serious complication may occur in patients
treated
The Circumstellar Structure and Excitation Effects around the Massive Protostar Cepheus A HW 2
We report SMA 335 GHz continuum observations with angular resolution of
~0.''3, together with VLA ammonia observations with ~1'' resolution toward Cep
A HW 2. We find that the flattened disk structure of the dust emission observed
by Patel et al. is preserved at the 0.''3 scale, showing an elongated structure
of ~$0.''6 size (450 AU) peaking on HW 2. In addition, two ammonia cores are
observed, one associated with a hot-core previously reported, and an elongated
core with a double peak separated by ~1.''3 and with signs of heating at the
inner edges of the gas facing HW 2. The double-peaked ammonia structure, as
well as the double-peaked CH3CN structure reported previously (and proposed to
be two independent hot-cores), surround both the dust emission as well as the
double-peaked SO2 disk structure found by Jimenez-Serra et al. All these
results argue against the interpretation of the elongated dust-gas structure as
due to a chance-superposition of different cores; instead, they imply that it
is physically related to the central massive object within a disk-protostar-jet
system.Comment: 12 pages, 3 figures; accepted for publication in the Astrophysical
Journa
Thermally Activated Reversible Threshold Shifts in Yba\u3csub\u3e2\u3c/sub\u3eCu\u3csub\u3e3\u3c/sub\u3eO\u3csub\u3e7-δ\u3c/sub\u3e/Yttria-Stabilized Zirconia/Si Capacitors
Yba2Cu3O7-δ/yttria‐stabilized zirconia (YSZ)/silicon superconductor–insulator–semiconductor capacitors are characterized with capacitance‐voltage (C‐V) measurements at different gate‐voltage sweep rates and under bias‐temperature cycling. It is shown that ionic conduction in YSZ causes both hysteresis and stretch‐out in room‐temperature C‐V curves. A thermally activated process with an activation energy of about 39 meV in YSZ and/or at YSZ/Si interface is attributed to trapping/detrapping mechanisms in the SiOx interfacial layer between YSZ and Si. The negative mobile ions in YSZ can be moved by an applied electric field at room temperature and then ‘‘frozen’’ with decreasing temperature, giving rise to adjustable threshold voltages at low temperatures
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