103,587 research outputs found
System and method for character recognition
A character recognition system is disclosed in which each character in a retina, defining a scanning raster, is scanned with random lines uniformly distributed over the retina. For each type of character to be recognized the system stores a probability density function (PDF) of the random line intersection lengths and/or a PDF of the random line number of intersections. As an unknown character is scanned, the random line intersection lengths and/or the random line number of intersections are accumulated and based on a comparison with the prestored PDFs a classification of the unknown character is performed
Pattern recognition technique
Technique operates regardless of pattern rotation, translation or magnification and successfully detects out-of-register patterns. It improves accuracy and reduces cost of various optical character recognition devices and page readers and provides data input to computer
Real time analysis of voiced sounds
A power spectrum analysis of the harmonic content of a voiced sound signal is conducted in real time by phase-lock-loop tracking of the fundamental frequency, (f sub 0) of the signal and successive harmonics (h sub 1 through h sub n) of the fundamental frequency. The analysis also includes measuring the quadrature power and phase of each frequency tracked, differentiating the power measurements of the harmonics in adjacent pairs, and analyzing successive differentials to determine peak power points in the power spectrum for display or use in analysis of voiced sound, such as for voice recognition
Quantitative Description of by the Hubbard Model in Infinite Dimensions
We show that the analytic single-particle density of states and the optical
conductivity for the half-filled Hubbard model on the Bethe lattice in infinite
dimensions describe quantitatively the behavior of the gap and the kinetic
energy ratio of the correlated insulator . The form of the optical
conductivity shows rising and is quite similar to the
experimental data, and the density of states shows behavior near
the band edges.Comment: 9 pages, revtex, 4 figures upon reques
Global aspects of accelerating and rotating black hole space-times
The complete family of exact solutions representing accelerating and rotating
black holes with possible electromagnetic charges and a NUT parameter is known
in terms of a modified Plebanski-Demianski metric. This demonstrates the
singularity and horizon structure of the sources but not that the complete
space-time describes two causally separated black holes. To demonstrate this
property, the metric is first cast in the Weyl-Lewis-Papapetrou form. After
extending this up to the acceleration horizon, it is then transformed to the
boost-rotation-symmetric form in which the global properties of the solution
are manifest. The physical interpretation of these solutions is thus clarified.Comment: 15 pages, 1 figure. To appear in Class. Quantum Gra
Spatial flocking: Control by speed, distance, noise and delay
Fish, birds, insects and robots frequently swim or fly in groups. During
their 3 dimensional collective motion, these agents do not stop, they avoid
collisions by strong short-range repulsion, and achieve group cohesion by weak
long-range attraction. In a minimal model that is isotropic, and continuous in
both space and time, we demonstrate that (i) adjusting speed to a preferred
value, combined with (ii) radial repulsion and an (iii) effective long-range
attraction are sufficient for the stable ordering of autonomously moving agents
in space. Our results imply that beyond these three rules ordering in space
requires no further rules, for example, explicit velocity alignment, anisotropy
of the interactions or the frequent reversal of the direction of motion,
friction, elastic interactions, sticky surfaces, a viscous medium, or vertical
separation that prefers interactions within horizontal layers. Noise and delays
are inherent to the communication and decisions of all moving agents. Thus,
next we investigate their effects on ordering in the model. First, we find that
the amount of noise necessary for preventing the ordering of agents is not
sufficient for destroying order. In other words, for realistic noise amplitudes
the transition between order and disorder is rapid. Second, we demonstrate that
ordering is more sensitive to displacements caused by delayed interactions than
to uncorrelated noise (random errors). Third, we find that with changing
interaction delays the ordered state disappears at roughly the same rate,
whereas it emerges with different rates. In summary, we find that the model
discussed here is simple enough to allow a fair understanding of the modeled
phenomena, yet sufficiently detailed for the description and management of
large flocks with noisy and delayed interactions. Our code is available at
http://github.com/fij/flocComment: 12 pages, 7 figure
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