7,449 research outputs found
Effect of bow-type initial imperfection on the buckling load and mass of graphite-epoxy blade-stiffened panels
A structural synthesis computer code which accounts for first order effects of an initial bow and which can be used for sizing stiffened composite panels having an arbitrary cross section is used to study graphite blade-stiffened panels. The effect of a small initial bow on both the load carrying ability of panels and on the mass of panels designed to carry a specified load is examined. Large reductions in the buckling load caused by a small initial bow emphasize the need for considering a bow when a panel is designed
Vibration and Instability of Plate-Assemblies including Shear and Anisotropy (VIPASA) user's guide, addendum
Extensions developed at Langley Research Center to the VIPASA computer program are described including a procedure for simple thermal stress analysis and options for graphical display of output. Input requirements for operation of the modified program are given in detail
Wavelength- and material-dependent absorption in GaAs and AlGaAs microcavities
The quality factors of modes in nearly identical GaAs and
Al_{0.18}Ga_{0.82}As microdisks are tracked over three wavelength ranges
centered at 980 nm, 1460 nm, and 1600 nm, with quality factors measured as high
as 6.62x10^5 in the 1600-nm band. After accounting for surface scattering, the
remaining loss is due to sub-bandgap absorption in the bulk and on the
surfaces. We observe the absorption is, on average, 80 percent greater in
AlGaAs than in GaAs and in both materials is 540 percent higher at 980 nm than
at 1600nm.Comment: 4 pages, 2 figures, 1 table, minor changes to disucssion of Qrad and
Urbach tai
A Calculus of Bounded Capacities
Resource control has attracted increasing interest in foundational research on distributed systems. This paper focuses on space control and develops an analysis of space usage in the context of an ambient-like calculus with bounded capacities and weighed processes, where migration and activation require space. A type system complements the dynamics of the calculus by providing static guarantees that the intended capacity bounds are preserved throughout the computation
PASCO: Structural panel analysis and sizing code: Users manual - Revised
A computer code denoted PASCO is described for analyzing and sizing uniaxially stiffened composite panels. Buckling and vibration analyses are carried out with a linked plate analysis computer code denoted VIPASA, which is included in PASCO. Sizing is based on nonlinear mathematical programming techniques and employs a computer code denoted CONMIN, also included in PASCO. Design requirements considered are initial buckling, material strength, stiffness and vibration frequency. A user's manual for PASCO is presented
Thrombolysis for acute graft occlusion during elective endovascular aortic aneurysm repair.
A 65-year-old man developed acute arterial thrombosis with stent graft occlusion, during elective endovascular aneurysm repair, with bilateral acute lower limb ischaemia. We describe successful endovascular and pharmacological management using a combination of mechanical disruption of the thrombus (using the access sheaths) followed by intra-arterial thrombolysis (Actilyse) infusion. Within 4-h the endograft had completely re-canalized. The patient made an uncomplicated recovery and was discharged on the second post-operative day
SU(3) Predictions of Decays in the Standard Model
With SU(3) symmetry one only needs 13 hadronic parameters to describe decays in the Standard Model. When annihilation contributions are
neglected, only 7 hadronic parameters are needed. These parameters can be
determined from existing experimental data and some unmeasured branching ratios
and CP asymmetries of the type can be predicted. In this talk we
present SU(3) predictions of branching ratios and CP asymmetries for
decays in the Standard Model.Comment: 4 pages, no figure. Talk present at the 5th International Conference
on Hyperons, Charm and Beauty Hadrons, Vancouver, June 200
Heavy Quarkonia - A Review of the Experimental Status
A review of the present status of the spectroscopy of heavy quarkonia
(b-bbar, c-cbar) is presented.Comment: 6 pages, 4 figures, Presented at the 11th International Conference In
Quantum ChromoDynamics (QCD 04), Montpellier, France, 5-9 July 200
Towards hardware acceleration of neuroevolution for multimedia processing applications on mobile devices
This paper addresses the problem of accelerating large artificial neural networks (ANN), whose topology and weights can evolve via the use of a genetic algorithm. The proposed digital hardware architecture is capable of processing any evolved network topology, whilst at the same time providing a good trade off between throughput, area and power consumption. The latter is vital for a longer battery life on mobile devices. The architecture uses multiple parallel arithmetic units in each processing element (PE). Memory partitioning and data caching are used to minimise the effects of PE pipeline stalling. A first order minimax polynomial approximation scheme, tuned via a genetic algorithm, is used for the activation function generator. Efficient arithmetic circuitry, which leverages modified Booth recoding, column compressors and carry save adders, is adopted throughout the design
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