The public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information.Send comments regarding this burden estimate or any other aspect of this collection of information, including suggesstions for reducing this burden, to Washington Headquarters Services, Directorate for Information Operations and Reports, 1215 Jefferson Davis Highway, Suite 1204, Arlington VA, 22202-4302. Respondents should be aware that notwithstanding any other provision of law, no person shall be subject to any oenalty for failing to comply with a collection of information if it does not display a currently valid OMB control number. PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ADDRESS. a. REPORT DIAGNOSTICS OF 3D DYNAMIC STALL ON ROTOR BLADES ABSTRACT SECURITY CLASSIFICATION OF:This project investigated the nature of the velocity field behind the separation line in dynamic stall on rotor blades, particularly the centrifugal effects and radial velocity field. Initial experiments were performed using a single-bladed rotor in hover with transient stall induced by an inflow obstructor. A 2-bladed teetering rotor setup was then constructed in the Georgia Tech 7' x 9' tunnel. PIV measurements confirmed the finding of discrete quasi-periodic streamwise vortical structures in the radial flow behind the separation line in both experiments. Co-rotating structures suggest that the free shear layer formed at stall rolls up into discrete cells. The spanwise spacing of structures is approximately the height of the separated flow region. The presence U

Enhancement techniques are employed in two vastly divergent venues in Chicago with the purpose of removing barriers to communication. In the first case, the marine environment scaled to house Beluga whales presents its own acoustical obstacle. In the second, the presence of a microphone can be an obstacle as seen by a poet with a message to share. The Poetry Foundation implemented a voice lift system in a sonorous environment that supports the voice or light amplification, but requires assistance to extend the reach of the unamplified talker. Natural acoustic design, design of traditional public address systems, and the introduction of enhancement techniques are all outlined for these two case studies to illustrate how the roles intersect. Both environments are live in their un-enhanced state. The unusual aspect of these projects is the use of enhancement to increase intelligibility within a naturally reverberant space.

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