6,384 research outputs found
Loads Due to Controls at Transonic and Low Supersonic Speeds
Some results of recent experimental investigations at supersonic and transonic speeds are presented to show the present status in the estimation of load distributions on controls and adjacent wing surfaces resulting from the deflection of flap controls and spoiler controls. The results indicate that the development of methods for predicting loads associated with controls has not kept pace with the acquisition of experimental data. At low supersonic speeds sweeping the hinge line induces strong three-dimensional-flow characteristics which cannot be treated by the simplified methods previously developed for controls without sweep. At transonic speeds the estimation of loads associated with controls must usually be dependent upon experimental information inasmuch as the latest attempts to predict chordwise and spanwise loadings have met with only limited success
Strongly Enhanced Hole-Phonon Coupling in the Metallic State of the Dilute Two-Dimensional Hole Gas
We have studied the temperature dependent phonon emission rate () of a
strongly interacting (22) dilute 2D GaAs hole system using a standard
carrier heating technique. In the still poorly understood metallic state, we
observe that () changes from () to ()
above 100mK, indicating a crossover from screened piezoelectric(PZ) coupling to
screened deformation potential(DP) coupling for hole-phonon scattering.
Quantitative comparison with theory shows that the long range PZ coupling
between holes and phonons has the expected magnitude; however, in the metallic
state, the short range DP coupling between holes and phonons is {\it almost
twenty times stronger} than expected from theory. The density dependence of
() shows that it is {\it easier} to cool low density 2D holes in GaAs
than higher density 2D hole systems.Comment: To appear in Phys. Rev. Let
Generalized BF Theory in Superspace as Underlying Theory of 11D Supergravity
We construct a generalized BF theory in superspace that can embed
eleven-dimensional supergravity theory. Our topological BF theory can
accommodate all the necessary Bianchi identities for teleparallel superspace
supergravity in eleven-dimensions, as the simplest but nontrivial solutions to
superfield equations for our superspace action. This indicates that our theory
may have solutions other than eleven-dimensional supergravity, accommodating
generalized theories of eleven-dimensional supergravity. Therefore our
topological theory can be a good candidate for the low energy limit of
M-theory, as an underlying fundamental theory providing a `missing link'
between eleven-dimensional supergravity and M-theory.Comment: 16 pages, latex, two new paragraphs in section 4 and in Concluding
Remarks with two new reference
Suppression of weak localization effects in low-density metallic 2D holes
We have measured the conductivity in a gated high-mobility GaAs two
dimensional hole sample with densities in the range (7-17)x10^9 cm^-2 and at
hole temperatures down to 5x10^-3 E_F. We measure the weak localization
corrections to the conductivity g=G/(e^2/h) as a function of magnetic field
(Delta g=0.019 +/- 0.006 at g=1.5 and T=9 mK) and temperature (d ln g/dT<0.0058
and 0.0084 at g=1.56 and 2.8). These values are less than a few percent of the
value 1/pi predicted by standard weak localization theory for a disordered 2D
Fermi liqui
Renormalizations in softly broken N=1 theories: Slavnov-Taylor identities
Slavnov-Taylor identities have been applied to perform explicitly the
renormalization procedure for the softly broken N=1 SYM. The result is in
accordance with the previous results obtained at the level of supergraph
technique.Comment: Latex, 17 pages, one statement about soft gauge beta function has
been change
Optimally combining dynamical decoupling and quantum error correction
We show how dynamical decoupling (DD) and quantum error correction (QEC) can
be optimally combined in the setting of fault tolerant quantum computing. To
this end we identify the optimal generator set of DD sequences designed to
protect quantum information encoded into stabilizer subspace or subsystem
codes. This generator set, comprising the stabilizers and logical operators of
the code, minimizes a natural cost function associated with the length of DD
sequences. We prove that with the optimal generator set the restrictive
local-bath assumption used in earlier work on hybrid DD-QEC schemes, can be
significantly relaxed, thus bringing hybrid DD-QEC schemes, and their
potentially considerable advantages, closer to realization.Comment: 6 pages, 1 figur
Pole Term and Gauge Invariance in Deep Inelastic Scattering
In this paper we reconcile two contradictory statements about deep inelastic
scattering (DIS) in manifestly covariant theories: (i) the scattering must be
gauge invariant, even in the deep inelastic limit, and (ii) the pole term
(which is not gauge invariant in a covariant theory) dominates the scattering
amplitude in the deep inelastic limit. An ``intermediate'' answer is found to
be true. We show that, at all energies, the gauge dependent part of the pole
term cancels the gauge dependent part of the rescattering term, so that both
the pole and rescattering terms can be separately redefined in a gauge
invariant fashion. The resulting, redefined pole term is then shown to dominate
the scattering in the deep inelastic limit. Details are worked out for a simple
example in 1+1 dimensions.Comment: 10 figure
Two-loop Gell-Mann-Low function of N=1 supersymmetric Yang-Mills theory, regularized by higher covariant derivatives
Two-loop Gell-Mann-Low function is calculated for N=1 supersymmetric
Yang-Mills theory, regularized by higher covariant derivatives. The integrals,
which define it, are shown to be reduced to total derivatives and can be easily
calculated analytically.Comment: 17 pages, 3 eps figure
- …