28,458 research outputs found
IR-transmission glasses formed from oxides of bismuth and tellurium
Bismuth trioxide-tellurium dioxide glasses have improved infrared transmission characteristics
High dielectric thick films for screened circuit capacitors
Techniques and materials have recently been developed to obtain high dielectric films /K of 300 to 800/. High dielectric barium titanate particles are mixed in a barium titanate glass
Aircraft-crash-locating transmitter features design improvements
Crash locater is automatically ejected from aircraft at time of crash and begins transmitting at emergency radio frequencies monitored by all airports and airport control towers. Advantages are smaller size, simpler design and installation, extended transmitting range and life, greater deployment reliability and increased crash resistance
Planar leaky light-guides and couplers
A quantitative theory of light propagation in a dielectric slab guide with general cladding media is presented. It is based on a plane wave which bounces in a zigzag fashion along the guide as a result of total or partial reflections at the two surfaces of the film. Two mechanisms are considered which contribute to the attenuation of the guide: losses due to absorption in the slab and cladding materials, and radiation losses if the guide is a leaky one. We point out the significance of the Goos-Hänchen effect for all questions relating to the power flow in the slab guide. The theory is illustrated by discussing dispersion and attenuation of guides with various low-index and high-index claddings, operating above and below cutoff. The low-index leaky guide is considered particularly in detail. Its high attenuation by leakage can be reduced to practically acceptable values (<1d B/cm) by increasing the film thickness to ≳ 40λ. One application of this guide is in the leaky wave coupler. This coupler may be viewed as a prism-film coupler simplified by omission of the gap. It offers a new approach to the problem of broad-band coupling to thin-film light guides
An analysis of the variation in wear life of hot pressed molybdenum disulfide-silver electrical contact brushes in vacuum
Wear life analysis of hot pressed molybdenum disulfide-silver electrical contact brushes in vacuu
Socle degrees, Resolutions, and Frobenius powers
We first describe a situation in which every graded Betti number in the tail
of the resolution of may be read from the socle degrees of . Then we apply the above result to the ideals and ; and
thereby describe a situation in which the graded Betti numbers in the tail of
the resolution of are equal to the graded Betti numbers in the tail
of a shift of the resolution of .Comment: 19 page
Geosynchrotron radio emission from CORSIKA-simulated air showers
Simulations of radio emission from extensive air showers we have published so
far were performed with a Monte Carlo code using analytical parametrisations to
describe the spatial, temporal, energy and angular particle distributions in
the air shower. A new version of our simulation code, which replaces these
parametrisations with precise, multi-dimensional histograms derived from
per-shower CORSIKA simulations, is now available. The new code allows an
independent selection between parametrisation and histogram for each of the
relevant distributions, enabling us to study the changes arising from using a
more realistic air shower model in detail. We describe the new simulation
strategy, present some initial results and discuss the new possibilities.Comment: 6 pages, Proceedings of the ARENA2006 workshop, Newcastle, England;
to be published in Journal of Physics: Conference Series (JPCS
An inverse of the evaluation functional for typed Lambda-calculus
In any model of typed λ-calculus conianing some basic
arithmetic, a functional p - * (procedure—* expression)
will be defined which inverts the evaluation functional
for typed X-terms, Combined with the evaluation
functional, p-e yields an efficient normalization algorithm.
The method is extended to X-calculi with constants
and is used to normalize (the X-representations
of) natural deduction proofs of (higher order) arithmetic.
A consequence of theoretical interest is a strong
completeness theorem for βη-reduction, generalizing
results of Friedman [1] and Statman [31: If two Xterms
have the same value in some model containing
representations of the primitive recursive functions
(of level 1) then they are provably equal in the βη-
calculus
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