Robust Adaptive LCMV Beamformer Based On An Iterative Suboptimal Solution

The main drawback of closed-form solution of linearly constrained minimum variance (CF-LCMV) beamformer is the dilemma of acquiring long observation time for stable covariance matrix estimates and short observation time to track dynamic behavior of targets, leading to poor performance including low signal-noise-ratio (SNR), low jammer-to-noise ratios (JNRs) and small number of snapshots. Additionally, CF-LCMV suffers from heavy computational burden which mainly comes from two matrix inverse operations for computing the optimal weight vector. In this paper, we derive a low-complexity Robust Adaptive LCMV beamformer based on an Iterative Suboptimal solution (RAIS-LCMV) using conjugate gradient (CG) optimization method. The merit of our proposed method is threefold. Firstly, RAIS-LCMV beamformer can reduce the complexity of CF-LCMV remarkably. Secondly, RAIS-LCMV beamformer can adjust output adaptively based on measurement and its convergence speed is comparable. Finally, RAIS-LCMV algorithm has robust performance against low SNR, JNRs, and small number of snapshots. Simulation results demonstrate the superiority of our proposed algorithms

Mass segregation in the outer halo globular cluster Palomar 14

We present evidence for mass segregation in the outer-halo globular cluster Palomar 14, which is intuitively unexpected since its present-day two-body relaxation time significantly exceeds the Hubble time. Based on archival Hubble Space Telescope imaging, we analyze the radial dependence of the stellar mass function in the cluster's inner 39.2 pc in the mass range of 0.53-0.80 M_sun, ranging from the main-sequence turn-off down to a V-band magnitude of 27.1 mag. The mass function at different radii is well approximated by a power law and rises from a shallow slope of 0.6+/-0.2 in the cluster's core to a slope of 1.6+/-0.3 beyond 18.6 pc. This is seemingly in conflict with the finding by Beccari et al. (2011), who interpret the cluster's non-segregated population of (more massive) blue straggler stars, compared to (less massive) red giants and horizontal branch stars, as evidence that the cluster has not experienced dynamical segregation yet. We discuss how both results can be reconciled. Our findings indicate that the cluster was either primordially mass-segregated and/or used to be significantly more compact in the past. For the latter case, we propose tidal shocks as the mechanism driving the cluster's expansion, which would imply that Palomar 14 is on a highly eccentric orbit. Conversely, if the cluster formed already extended and with primordial mass segregation, this could support an accretion origin of the cluster.Comment: 14 pages, 8 figures, accepted for publication in MNRA

Landslide Denied: Exit Polls vs. Vote Count 2006

There was an unprecedented level of concern approaching the 2006 Election ("E2006") about the vulnerability of the vote counting process to manipulation. With questions about the integrity of the 2000, 2002 and 2004 elections remaining unresolved, with e-voting having proliferated nationwide, and with incidents occurring with regularity through 2005 and 2006, the alarm spread from computer experts to the media and the public at large. It would be fair to say that America approached E2006 with held breath.For many observers, the results on Election Day permitted a great sigh of relief -- not because control of Congress shifted from Republicans to Democrats, but because it appeared that the public will had been translated more or less accurately into electoral results, not thwarted as some had feared. There was a relieved rush to conclude that the vote counting process had been fair and the concerns of election integrity proponents overblown.Unfortunately the evidence forces us to a very different and disturbing conclusion: there was gross vote count manipulation and it had a great impact on the results of E2006, significantly decreasing the magnitude of what would have been, accurately tabulated, a landslide of epic proportions. Because much of this manipulation appears to have been computer-based, and therefore invisible to the legions of at-the-poll observers, the public was informed of the usual "isolated incidents and glitches" but remains unaware of the far greater story: The electoral machinery and vote counting systems of the United States did not honestly and accurately translate the public will and certainly can not be counted on to do so in the future

Development of acceptance criteria for batches of silane primer for external tank thermal protection system bonding applications

Concluding tests for the thermogravimetric and FTIR analyses of DC 1200 silane primers are discussed as well as methods for HPLC and GC analyses and for determining titanium and silicon by atomic absorption spectroscopy. Tables summarizes results obtained for residue, ash, titanium, silicone, Si/Ti ratio, OH-absorption, the lap-shear test, and the GC headspace for alcohols