19,674 research outputs found
A theoretical approach to sound propagation and radiation for ducts with suppressors
The several phenomena involved in theoretical prediction of the far-field sound radiation attenuation from an acoustically lined duct were studied. These include absorption by the suppressor, termination reflections, and far-field radiation. Extensive parametric studies show that the suppressor absorption performance can be correlated with mode cut-off ratio or angle of propagation. The other phenomena can be shown to depend explicitly upon mode cut-off ratio. A complete system can thus be generated which can be used to evaluate aircraft sound suppressors and which can be related to the sound source through the cut-off ratio-acoustic power distribution. Although the method is most fully developed for inlet suppressors, several aft radiated noise phenomena are also discussed. This simplified suppressor design and evaluation method is summarized, the recent improvements in the technique are presented, and areas where further refinement is necessary are discussed. Noise suppressor data from engine experiments are compared with the theoretical calculations
Research Study for Determination of Liquid Surface Profile in a Cryogenic Tank During Gas Injection Annual Report, 18 Jun. 1967 - 17 Jun. 1968
Determining entrainment of entrapped liquid as function of air flow, and viscosit
Research Study for Determination of Liquid Surface Profile in a Cryogenic Tank During Gas Injection Quarterly Report, 18 Dec. 1967 - 17 Mar. 1968
Correlation equation on entrainment-viscosity behavior in cryogenic tank during gas injectio
Umklapp scattering as the origin of -linear resistivity in the normal state of high- cuprate superconductors
The high-temperature normal state of the unconventional cuprate
superconductors has resistivity linear in temperature , which persists to
values well beyond the Mott-Ioffe-Regel upper bound. At low-temperature, within
the pseudogap phase, the resistivity is instead quadratic in , as would be
expected from Fermi liquid theory. Developing an understanding of these normal
phases of the cuprates is crucial to explain the unconventional
superconductivity. We present a simple explanation for this behavior, in terms
of umklapp scattering of electrons. This fits within the general picture
emerging from functional renormalization group calculations that spurred the
Yang-Rice-Zhang ansatz: umklapp scattering is at the heart of the behavior in
the normal phase.Comment: v1 6+1 pages, 4 figures; v2 6+2 pages, 4 figures; v3 6 + 2.5 pages, 5
figure
T.J. Rice responds to negative reactions
T.J. Rice responds to negative reactions to his comments, stating that there were misunderstandings which he seeks to clarify. Dated December 1, 1975
Magnetic Response in the Underdoped Cuprates
We examine the dynamical magnetic response of the underdoped cuprates by
employing a phenomenological theory of a doped resonant valence bond state
where the Fermi surface is truncated into four pockets. This theory predicts a
resonant spin response which with increasing energy (0 to 100meV) appears as an
hourglass. The very low energy spin response is found at (pi,pi +- delta) and
(pi +- delta,pi) and is determined by scattering from the pockets' frontside to
the tips of opposite pockets where a van Hove singularity resides. At energies
beyond 100 meV, strong scattering is seen from (pi,0) to (pi,pi). This theory
thus provides a semi-quantitative description of the spin response seen in both
INS and RIXS experiments at all relevant energy scales
The Magnetic Topology of the Weak-Lined T Tauri Star V410 - A Simultaneous Temperature and Magnetic Field Inversion
We present a detailed temperature and magnetic investigation of the T Tauri
star V410 Tau by means of a simultaneous Doppler- and Zeeman-Doppler Imaging.
Moreover we introduce a new line profile reconstruction method based on a
singular value decomposition (SVD) to extract the weak polarized line profiles.
One of the key features of the line profile reconstruction is that the SVD line
profiles are amenable to radiative transfer modeling within our Zeeman-Doppler
Imaging code iMap. The code also utilizes a new iterative regularization scheme
which is independent of any additional surface constraints. To provide more
stability a vital part of our inversion strategy is the inversion of both
Stokes I and Stokes V profiles to simultaneously reconstruct the temperature
and magnetic field surface distribution of V410 Tau. A new image-shear analysis
is also implemented to allow the search for image and line profile distortions
induced by a differential rotation of the star. The magnetic field structure we
obtain for V410 Tau shows a good spatial correlation with the surface
temperature and is dominated by a strong field within the cool polar spot. The
Zeeman-Doppler maps exhibit a large-scale organization of both polarities
around the polar cap in the form of a twisted bipolar structure. The magnetic
field reaches a value of almost 2 kG within the polar region but smaller fields
are also present down to lower latitudes. The pronounced non-axisymmetric field
structure and the non-detection of a differential rotation for V410 Tau
supports the idea of an underlying -type dynamo, which is predicted
for weak-lined T Tauri stars.Comment: Accepted for A&A, 18 pages, 10 figure
APPLICATION OF THE MODULARIZATION CONCEPT TO SATELLITE TAPE RECORDERS
Application of the modularization concept to satellite tape recorder
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