40,562 research outputs found
The refractive characteristics and intraocular tensions of colony chimpanzees Technical report, Aug. 1965
Refraction and intraocular pressure tests of colony chimpanzees - age relationshi
Time-fixed rendezvous by impulse factoring with an intermediate timing constraint
A method is presented for factoring a two-impulse orbital transfer into a three- or four-impulse transfer which solves the rendezvous problem and satisfies an intermediate timing constraint. Both the time of rendezvous and the intermediate time of a alinement are formulated as any element of a finite sequence of times. These times are integer multiples of a constant plus an additive constant. The rendezvous condition is an equality constraint, whereas the intermediate alinement is an inequality constraint. The two timing constraints are satisfied by factoring the impulses into collinear parts that vectorially sum to the original impulse and by varying the resultant period differences and the number of revolutions in each orbit. Five different types of solutions arise by considering factoring either or both of the two impulses into two or three parts with a limit for four total impulses. The impulse-factoring technique may be applied to any two-impulse transfer which has distinct orbital periods
Ultrasound and phakometry measurements of the primate eye Technical report, Aug. 1965
Ultrasonic testing and phakometry measurements of primate ey
Feasibility study of the ultraviolet spectral analysis of the lunar surface
Ultraviolet spectral analysis of granite, gabbro, and serpentinite samples to determine feasibility of mapping surface composition of moo
Modification of an impulse-factoring orbital transfer technique to account for orbit determination and maneuver execution errors
A method has previously been developed to satisfy terminal rendezvous and intermediate timing constraints for planetary missions involving orbital operations. The method uses impulse factoring in which a two-impulse transfer is divided into three or four impulses which add one or two intermediate orbits. The periods of the intermediate orbits and the number of revolutions in each orbit are varied to satisfy timing constraints. Techniques are developed to retarget the orbital transfer in the presence of orbit-determination and maneuver-execution errors. Sample results indicate that the nominal transfer can be retargeted with little change in either the magnitude (Delta V) or location of the individual impulses. Additonally, the total Delta V required for the retargeted transfer is little different from that required for the nominal transfer. A digital computer program developed to implement the techniques is described
Blind Normalization of Speech From Different Channels
We show how to construct a channel-independent representation of speech that
has propagated through a noisy reverberant channel. This is done by blindly
rescaling the cepstral time series by a non-linear function, with the form of
this scale function being determined by previously encountered cepstra from
that channel. The rescaled form of the time series is an invariant property of
it in the following sense: it is unaffected if the time series is transformed
by any time-independent invertible distortion. Because a linear channel with
stationary noise and impulse response transforms cepstra in this way, the new
technique can be used to remove the channel dependence of a cepstral time
series. In experiments, the method achieved greater channel-independence than
cepstral mean normalization, and it was comparable to the combination of
cepstral mean normalization and spectral subtraction, despite the fact that no
measurements of channel noise or reverberations were required (unlike spectral
subtraction).Comment: 25 pages, 7 figure
Structure and magnetism in nanocrystalline Ca(La)B films
Nanocrystalline films of La-doped CaB have been fabricated by using a
rf-magnetron sputtering. Lattice expansion of up to 6% with respect to the bulk
value was observed along the direction perpendicular to the film plane, which
arises from the trapping of Ar gas into the film. Large ferromagnetic moment of
3 ~ 4 Bohr magneton per La has been observed in some La-doped films only when
the lattice expansion rate is larger than 2.5%.Comment: 2 pages, 2 figures, to appear in J. Magn. Magn. Mate
Chiral extrapolation beyond the power-counting regime
Chiral effective field theory can provide valuable insight into the chiral
physics of hadrons when used in conjunction with non-perturbative schemes such
as lattice QCD. In this discourse, the attention is focused on extrapolating
the mass of the rho meson to the physical pion mass in quenched QCD (QQCD).
With the absence of a known experimental value, this serves to demonstrate the
ability of the extrapolation scheme to make predictions without prior bias. By
using extended effective field theory developed previously, an extrapolation is
performed using quenched lattice QCD data that extends outside the chiral
power-counting regime (PCR). The method involves an analysis of the
renormalization flow curves of the low energy coefficients in a finite-range
regularized effective field theory. The analysis identifies an optimal
regulator, which is embedded in the lattice QCD data themselves. This optimal
regulator is the regulator value at which the renormalization of the low energy
coefficients is approximately independent of the range of quark masses
considered. By using recent precision, quenched lattice results, the
extrapolation is tested directly by truncating the analysis to a set of points
above 380 MeV, while being blinded of the results probing deeply into the
chiral regime. The result is a successful extrapolation to the chiral regime.Comment: 8 pages, 18 figure
Behavior of the Escape Rate Function in Hyperbolic Dynamical Systems
For a fixed initial reference measure, we study the dependence of the escape
rate on the hole for a smooth or piecewise smooth hyperbolic map. First, we
prove the existence and Holder continuity of the escape rate for systems with
small holes admitting Young towers. Then we consider general holes for Anosov
diffeomorphisms, without size or Markovian restrictions. We prove bounds on the
upper and lower escape rates using the notion of pressure on the survivor set
and show that a variational principle holds under generic conditions. However,
we also show that the escape rate function forms a devil's staircase with jumps
along sequences of regular holes and present examples to elucidate some of the
difficulties involved in formulating a general theory.Comment: 21 pages. v2 differs from v1 only by additions to the acknowledgment
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