• 1–2.4 μm Near-IR Spectrum of the Giant Planet β Pictoris b Obtained with the Gemini Planet Imager

      Chilcote, Jeffrey; Pueyo, Laurent; De Rosa, Robert J.; Vargas, Jeffrey; Macintosh, Bruce; Bailey, Vanessa P.; Barman, Travis S.; Bauman, Brian; Bruzzone, Sebastian; Bulger, Joanna; et al. (IOP PUBLISHING LTD, 2017-03-28)
      Using the Gemini Planet Imager located at Gemini South, we measured the near-infrared (1.0-2.4 mu m) spectrum of the planetary companion to the nearby, young star beta. Pictoris. We compare the spectrum obtained with currently published model grids and with known substellar objects and present the best matching models as well as the best matching observed objects. Comparing the empirical measurement of the bolometric luminosity to evolutionary models, we find a mass of 12.9. +/- 0.2. M-Jup, an effective temperature of 1724. +/- 15 K, a radius of 1.46. +/- 0.01. R-Jup, and a surface gravity of log g = 4.18. 0.01 [dex] (cgs). The stated uncertainties are statistical errors only, and do not incorporate any uncertainty on the evolutionary models. Using atmospheric models, we find an effective temperature of 1700-1800 K and a surface gravity of log g = 3.5-4.0 [dex] depending upon the model. These values agree well with other publications and with "hot-start" predictions from planetary evolution models. Further, we find that the spectrum of beta Pic. b best matches a low surface gravity L2. +/- 1 brown dwarf. Finally, comparing the spectrum to field brown dwarfs, we find the the spectrum best matches 2MASS J04062677- 381210 and 2MASS J03552337 + 1133437.
    • 2-D LDPC Codes and Joint Detection and Decoding for Two-Dimensional Magnetic Recording

      Matcha, Chaitanya Kumar; Roy, Shounak; Bahrami, Mohsen; Vasic, Bane; Srinivasa, Shayan Garani; Univ Arizona, Dept Elect & Comp Engn (IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 2018-02)
      Two-dimensional magnetic recording (TDMR) is a promising technology for boosting areal densities (ADs) using sophisticated signal processing algorithms within a systems framework. The read/write channel architectures have to effectively tackle 2-D inter-symbol interference (ISI), 2-D synchronization errors, media and electronic noise sources, as well as thermal asperities resulting in burst erasures. The 1-D low-density parity check (LDPC) codes are well studied to correct large 1-D burst errors/erasures. However, such 1-D LDPC codes are not suitable for correcting 2-D burst errors/erasures due to the 2-D span of errors. In this paper, we propose construction of a native 2-D LDPC code to effectively correct 2-D burst erasures. We also propose a joint detection and decoding engine based on the generalized belief propagation algorithm to simultaneously handle 2-D ISI, as well as correct bit/burst errors for TDMR channels. This paper is novel in two aspects: 1) we propose the construction of native 2-D LDPC codes to correct large 2-D burst erasures and 2) we develop a 2-D joint signal detection-decoder engine that incorporates 2-D ISI constraints, and modulation code constrains along with LDPC decoding. The native 2-D LDPC code can correct >20% more burst erasures compared with the 1-D LDPC code over a 128 x 256 2-D page of detected bits. Also, the proposed algorithm is observed to achieve a signal-to-noise ratio gain of >0.5 dB in bit error rate performance (translating to 10% increase in ADs around the 1.8 Tb/in(2) regime with grain sizes of 9 nm) as compared with a decoupled detector-decoder system configuration over a small 2-D LDPC code of size 16 x 16. The efficacy of our proposed algorithm and system architecture is evaluated by assessing AD gains via simulations for a TDMR configuration comprising of a 2-D generalized partial response over the Voronoi media model assuming perfect 2-D synchronization.
    • 2001: UA Orthophotos (0.5' Resolution), Section A

      DTM Mapping; University of Arizona - Campus and Facilities Planning; University of Arizona (2001)
    • 2001: UA Orthophotos (0.5' Resolution), Section B

      DTM Mapping; University of Arizona -- Campus and Facilities Planning; University of Arizona (2001)
    • 2001: UA Orthophotos (0.5' Resolution), Section C

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    • 2001: UA Orthophotos (0.5' Resolution), Section D

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    • 2001: UA Orthophotos (2' Resolution), Sheets 1-14

      DTM Mapping; University of Arizona - Campus and Facilities Planning; University of Arizona (2001)