135,210 research outputs found
Pattern Synthesis of Dual-band Shared Aperture Interleaved Linear Antenna Arrays
This paper presents an approach to improve the efficiency of an array aperture by interleaving two different arrays in the same aperture area. Two sub-arrays working at different frequencies are interleaved in the same linear aperture area. The available aperture area is efficiently used. The element positions of antenna array are optimized by using Invasive Weed Optimization (IWO) to reduce the peak side lobe level (PSLL) of the radiation pattern. To overcome the shortness of traditional methods which can only fulfill the design of shared aperture antenna array working at the same frequency, this method can achieve the design of dual-band antenna array with wide working frequency range. Simulation results show that the proposed method is feasible and efficient in the synthesis of dual-band shared aperture antenna array
Pi pi scattering lengths at O(p^6) revisited
This article completes a former work where part of the O(p^6) low-energy
constants entering in the pi pi scattering were estimated. Some resonance
contributions were missed in former calculations and slight differences
appeared with respect to our outcome. Here, we provide the full results for all
the contributing O(p^6) couplings. We also perform a reanalysis of the hadronic
inputs used for the estimation (resonance masses, widths...). Their reliability
was checked together with the impact of the input uncertainties on the
determinations of the chiral couplings and the scattering lengths a^I_J. Our
outcome is found in agreement with former works though with slightly larger
errors. However, the effect in the final values of the a^I_J is negligible
after combining them with the other uncertainties. Based on this consistency,
we conclude that the previous scattering length determinations seem to be
rather solid and reliable, with the cO(p^6) low-energy constants quite under
control. Nevertheless, the uncertainties found in the present work point out
the limitation on further improvements unless the precision of the O(p^6)
couplings is properly increased.Comment: 19 pages. Improved treatment of the a0 decay width and update of the
numerical outcomes. Final version published in Phys. Rev. D
(10.1103/PhysRevD.79.096006
Some new -congruences for truncated basic hypergeometric series
We provide several new -congruences for truncated basic hypergeometric
series, mostly of arbitrary order. Our results include congruences modulo the
square or the cube of a cyclotomic polynomial, and in some instances,
parametric generalizations thereof. These are established by a variety of
techniques including polynomial argument, creative microscoping (a method
recently introduced by the first author in collaboration with Zudilin),
Andrews' multiseries generalization of the Watson transformation, and
induction. We also give a number of related conjectures including congruences
modulo the fourth power of a cyclotomic polynomial.Comment: 14 pages, more background and references adde
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