Report of tests of a compressor configuration of DCA blading.

Results of an experimental program to measure the performance of a compressor stator cascade consisting of 20 DCA blades of chord 5.01 inches, aspect ratio 2.0 and solidity 1.67 under conditions of varying incidence angle and Reynolds number are reported. Flow quality and blade performance data were obtained using pneumatic probe surveys and surface pressure measurements. Changes in Reynolds number in the range of 500,000 to 770,000 did not measurably effect either flow quality or blade performance. Changes in incidence angle over the range -15 to 10 degrees produced generally well behaved blade performance parameters.http://archive.org/details/reportoftestsofc00himeNALieutenant Commander, United States NavyApproved for public release; distribution is unlimited

Proxima Centauri b is not a transiting exoplanet

We report Spitzer Space Telescope observations during predicted transits of the exoplanet Proxima Centauri b. As the nearest terrestrial habitable-zone planet we will ever discover, any potential transit of Proxima b would place strong constraints on its radius, bulk density, and atmosphere. Subsequent transmission spectroscopy and secondary-eclipse measurements could then probe the atmospheric chemistry, physical processes, and orbit, including a search for biosignatures. However, our photometric results rule out planetary transits at the 200~ppm level at 4.5$~{\mu}m$, yielding a 3$\sigma$ upper radius limit of 0.4~R_\rm{\oplus} (Earth radii). Previous claims of possible transits from optical ground- and space-based photometry were likely correlated noise in the data from Proxima Centauri's frequent flaring. Follow-up observations should focus on planetary radio emission, phase curves, and direct imaging. Our study indicates dramatically reduced stellar activity at near-to-mid infrared wavelengths, compared to the optical. Proxima b is an ideal target for space-based infrared telescopes, if their instruments can be configured to handle Proxima's brightness.Comment: 8 pages, 3 figures, 2 tables, accepted for publication in MNRA