3,099 research outputs found
Studies on the interference of wings and propeller slipstreams
The small disturbance potential flow theory is applied to determine the lift of an airfoil in a nonuniform parallel stream. The given stream is replaced by an equivalent stream with a certain number of velocity discontinuities, and the influence of these discontinuities is obtained by the method of images. Next, this method is extended to the problem of an airfoil in a nonuniform stream of smooth velocity profile. This model allows perturbation velocity potential in a rotational undisturbed stream. A comparison of these results with numerical solutions of Euler equations indicates that, although approximate, the present method provides useful information about the interaction problem while avoiding the need to solve the Euler equations
Linearized potential solution for an airfoil in nonuniform parallel streams
A small perturbation potential flow theory is applied to the problem of determining the chordwise pressure distribution, lift and pitching moment of a thin airfoil in the middle of five parallel streams. This theory is then extended to the case of an undisturbed stream having a given smooth velocity profile. Two typical examples are considered and the results obtained are compared with available solutions of Euler's equations. The agreement between these two results is not quite satisfactory. Possible reasons for the differences are indicated
A modified lifting line theory for wing-propeller interference
An inviscid incompressible model for the interaction of a wing with a single propeller slipstream is presented. The model allows the perturbation quantities to be potential even though the undisturbed flow is rotational. The governing equations for the spanwise lift distribution are derived and a simple method of solving these is indicated. Spanwise lift and induced drag distribution for two cases are computed
Ergodicity from Nonergodicity in Quantum Correlations of Low-dimensional Spin Systems
Correlations between the parts of a many-body system, and its time dynamics,
lie at the heart of sciences, and they can be classical as well as quantum.
Quantum correlations are traditionally viewed as constituted out of classical
correlations and magnetizations. While that of course remains so, we show that
quantum correlations can have statistical mechanical properties like
ergodicity, which is not inherited from the corresponding classical
correlations and magnetizations, for the transverse anisotropic quantum XY
model in one-, two-, and quasi two-dimension, for suitably chosen transverse
fields and temperatures. The results have the potential for applications in
decoherence effects in realizable quantum computers.Comment: 8 pages, 6 figures, RevTeX 4.
Joint Measurability and Temporal Steering
Quintino et. al. (Phys. Rev. Lett. 113, 160402 (2014)) and Uola et. al.
(Phys. Rev. Lett. 113, 160403 (2014)) have recently established an intrinsic
relation between non-joint measurability and Einstein-Podolsky- Rosen steering.
They showed that a set of measurements is incompatible (i.e., not jointly
measurable) if and only if it can be used for the demonstration of steering. In
this paper, we prove the temporal analog of this result viz., a set of
measurements are incompatible if and only if it exhibits temporal steering.Comment: 6 pages,no figures, typos corrected, improved presentation; To appear
in JOSA B feature issue "80 years of Steering and the Einstein-Podolsky-Rosen
Paradox
Eficiência relativa de fontes de silício no controle de brusone nas folhas em arroz.
A adubação silicatada constitui uma das alternativas para diminuir o uso de fungicidas no controle da brusone em arroz. Foi realizado um experimento, durante 1999/2000 e repetido durante 2000/2001, com o objetivo de estudar a eficiência relativa de fontes de silício (Si) na redução da severidade da brusone nas folhas da cultivar Metica-1, em área de várzea
Local Invariants and Pairwise Entanglement in Symmetric Multi-qubit System
Pairwise entanglement properties of a symmetric multi-qubit system are
analyzed through a complete set of two-qubit local invariants. Collective
features of entanglement, such as spin squeezing, are expressed in terms of
invariants and a classifcation scheme for pairwise entanglement is proposed.
The invariant criteria given here are shown to be related to the recently
proposed (Phys. Rev. Lett. 95, 120502 (2005)) generalized spin squeezing
inequalities for pairwise entanglement in symmetric multi-qubit states.Comment: 9 pages, 2 figures, REVTEX, Replaced with a published versio
A Taxonomy of Deep Convolutional Neural Nets for Computer Vision
Traditional architectures for solving computer vision problems and the degree
of success they enjoyed have been heavily reliant on hand-crafted features.
However, of late, deep learning techniques have offered a compelling
alternative -- that of automatically learning problem-specific features. With
this new paradigm, every problem in computer vision is now being re-examined
from a deep learning perspective. Therefore, it has become important to
understand what kind of deep networks are suitable for a given problem.
Although general surveys of this fast-moving paradigm (i.e. deep-networks)
exist, a survey specific to computer vision is missing. We specifically
consider one form of deep networks widely used in computer vision -
convolutional neural networks (CNNs). We start with "AlexNet" as our base CNN
and then examine the broad variations proposed over time to suit different
applications. We hope that our recipe-style survey will serve as a guide,
particularly for novice practitioners intending to use deep-learning techniques
for computer vision.Comment: Published in Frontiers in Robotics and AI (http://goo.gl/6691Bm
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