3,999 research outputs found
On the eigenvalues of some nonhermitian oscillators
We consider a class of one-dimensional nonhermitian oscillators and discuss
the relationship between the real eigenvalues of PT-symmetric oscillators and
the resonances obtained by different authors. We also show the relationship
between the strong-coupling expansions for the eigenvalues of those
oscillators. Comparison of the results of the complex rotation and the
Riccati-Pad\'{e} methods reveals that the optimal rotation angle converts the
oscillator into either a PT-symmetric or an Hermitian one. In addition to the
real positive eigenvalues the PT-symmetric oscillators exhibit real positive
resonances under different boundary conditions. They can be calculated by means
of the straightforward diagonalization method. The Riccati-Pad\'e method yields
not only the resonances of the nonhermitian oscillators but also the
eigenvalues of the PT-symmetric ones
Specific-to-General Learning for Temporal Events with Application to Learning Event Definitions from Video
We develop, analyze, and evaluate a novel, supervised, specific-to-general
learner for a simple temporal logic and use the resulting algorithm to learn
visual event definitions from video sequences. First, we introduce a simple,
propositional, temporal, event-description language called AMA that is
sufficiently expressive to represent many events yet sufficiently restrictive
to support learning. We then give algorithms, along with lower and upper
complexity bounds, for the subsumption and generalization problems for AMA
formulas. We present a positive-examples--only specific-to-general learning
method based on these algorithms. We also present a polynomial-time--computable
``syntactic'' subsumption test that implies semantic subsumption without being
equivalent to it. A generalization algorithm based on syntactic subsumption can
be used in place of semantic generalization to improve the asymptotic
complexity of the resulting learning algorithm. Finally, we apply this
algorithm to the task of learning relational event definitions from video and
show that it yields definitions that are competitive with hand-coded ones
Evaluation of thermally stable phosphor screens for application in laser diode excited high brightness white light modules
A study on the preparation of thermally stable phosphor targets based on yttrium aluminum garnet doped with cerium (YAG:Ce) when excited by a high power laser diode is described. The luminous flux, chromaticity and radial spectral flux of the targets along with their thermal stability have been determined when exposed to laser powers of up to 5000 mW. This report presents successful high brightness light sources with adjustable emission properties achieved by utilizing thermally stable phosphor targets excited by high power laser diodes.Brunel University London, No. EP/K504208/
The Power of Mercy in \u3cem\u3eThe Hobbit\u3c/em\u3e and \u3cem\u3eThe Lord of the Rings\u3c/em\u3e
Alien Registration- Smith, Fern M. (Houlton, Aroostook County)
https://digitalmaine.com/alien_docs/34853/thumbnail.jp
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