16,504 research outputs found
Experiments with an Airfoil Model on which the Boundary Layers are Controlled Without the Use of Supplementary Equipment
This report describes test made in the Variable Density Wind Tunnel of the NACA to determine the possibility of controlling the boundary layer on the upper surface of an airfoil by use of the low pressure existing near the leading edge. The low pressure was used to induce flow through slots in the upper surface of the wing. The tests showed that the angle of attack for maximum lift was increased at the expense of a reduction in the maximum lift coefficient and an increase in the drag coefficient
Independent axiom systems for nearlattices
A nearlattice is a join semilattice such that every principal filter is a
lattice with respect to the induced order. Hickman and later Chajda et al
independently showed that nearlattices can be treated as varieties of algebras
with a ternary operation satisfying certain axioms. Our main result is that the
variety of nearlattices is 2-based, and we exhibit an explicit axiom system of
two independent identities. We also show that the original axiom systems of
Hickman and of Chajda et al are, respectively, dependent.Comment: 16 pages in 12pt; v2: minor changes suggested by referee, to appear
in Czechoslovak Math.
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Spatial attention shifting and phonological processing in adults with dyslexia
According to Hari and Renvall’s (2001) sluggish attentional shifting (SAS) hypothesis people with dyslexia have a central deficit in attention shifting. Here we assessed whether a group of adults with dyslexia showed impaired performance on shifting visual spatial attention. Twelve adults with dyslexia and 12 control adult participants took part in a Posner style focused attention orientation task and a shift attention orientation task. The participants also completed standardized measures of single word reading, spelling, IQ, phonological processing, speed of processing and non-word reading. Overall, the dyslexic participants showed the same pattern of performance as the control participants on the attention-orienting task, but completed the tasks at a consistently slower pace. Specifically, participants in both groups found short target presentation intervals more difficult than longer target presentation intervals, and participants in both groups were more impaired when cue-to-target information was invalid 20% of the time (shift task) than when it was valid all of the time (focused task). However, the group with dyslexia was significantly more impaired across the board
Shock induced boundary layer over a semi-infinite flat plate. Part 1: Flow in the immediate vicinity of the shock wave
Laminar, two dimensional boundary layer generated in immediate vicinity of plane shock wave moving over flat plate into gas initially at res
Shock induced boundary layer over a semi-infinite flat plate. Part 2: Complete problem
Numerical analysis of shock induced boundary layer flow on semi-infinite flat plate - Part
The Prediction of Mass of Z'-Boson from Mixing
B_q^0-B_^0 bar mixing offers a profound probe into the effects of new
physics beyond the Standard Model. In this paper, and
mass differences are considered taking the effect of both
Z-and Z' -mediated flavour-changing neutral currents in the
mixing (q = d, s). Our estimated mass of Z' boson is accessible at the
experiments LHC and B-factories in near future.Comment: 11 pages, 02 Figure
Trident pair production in strong laser pulses
We calculate the trident pair production amplitude in a strong laser
background. We allow for finite pulse duration, while still treating the laser
fields nonperturbatively in strong-field QED. Our approach reveals explicitly
the individual contributions of the one-step and two-step processes. We also
expose the role gauge invariance plays in the amplitudes and discuss the
relation between our results and the optical theorem.Comment: 4 pages, 1 .eps figure. Version 2: reference added, published versio
An evaluation of the NASA Tech House, including live-in test results, volume 1
The NASA Tech House was designed and constructed at the NASA Langley Research Center, Hampton, Virginia, to demonstrate and evaluate new technology potentially applicable for conservation of energy and resources and for improvements in safety and security in a single-family residence. All technology items, including solar-energy systems and a waste-water-reuse system, were evaluated under actual living conditions for a 1 year period with a family of four living in the house in their normal lifestyle. Results are presented which show overall savings in energy and resources compared with requirements for a defined similar conventional house under the same conditions. General operational experience and performance data are also included for all the various items and systems of technology incorporated into the house design
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