3,327 research outputs found
Precision pointing compensation for DSN antennas with optical distance measuring sensors
The pointing control loops of Deep Space Network (DSN) antennas do not account for unmodeled deflections of the primary and secondary reflectors. As a result, structural distortions due to unpredictable environmental loads can result in uncompensated boresight shifts which degrade pointing accuracy. The design proposed here can provide real-time bias commands to the pointing control system to compensate for environmental effects on pointing performance. The bias commands can be computed in real time from optically measured deflections at a number of points on the primary and secondary reflectors. Computer simulations with a reduced-order finite-element model of a DSN antenna validate the concept and lead to a proposed design by which a ten-to-one reduction in pointing uncertainty can be achieved under nominal uncertainty conditions
Dynamical nucleus-nucleus potential at short distances
The dynamical nucleus-nucleus potentials for fusion reactions 40Ca+40Ca,
48Ca+208Pb and 126Sn+130Te are studied with the improved quantum molecular
dynamics (ImQMD) model together with the extended Thomas-Fermi approximation
for the kinetic energies of nuclei. The obtained fusion barrier for 40Ca+40Ca
is in good agreement with the extracted fusion barrier from the measured fusion
excitation function, and the depth of the fusion pockets are close to the
results of time-dependent Hartree-Fock calculations. The energy dependence of
fusion barrier is also investigated. For heavy fusion system, the fusion pocket
becomes shallow and almost disappears for symmetric systems and the obtained
potential at short distances is higher than the adiabatic potential.Comment: 6 figures, accepted for publication in Phys. Rev.
Pesquisas em reprodução fomentam mudanças tecnológicas na suinocultura.
Projeto: 11.11.11.111
Cyclic mutually unbiased bases, Fibonacci polynomials and Wiedemann's conjecture
We relate the construction of a complete set of cyclic mutually unbiased
bases, i. e., mutually unbiased bases generated by a single unitary operator,
in power-of-two dimensions to the problem of finding a symmetric matrix over
F_2 with an irreducible characteristic polynomial that has a given Fibonacci
index. For dimensions of the form 2^(2^k) we present a solution that shows an
analogy to an open conjecture of Wiedemann in finite field theory. Finally, we
discuss the equivalence of mutually unbiased bases.Comment: 11 pages, added chapter on equivalenc
Aumento do peso e redução da idade a puberdade de leitoas através dos cruzamentos.
bitstream/item/58795/1/CUsersPiazzonDocuments151.pd
Fêmeas cruzadas ou F1 recomendadas para a produção de suínos para o abate.
bitstream/item/58663/1/CUsersPiazzonDocuments184.pd
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