Stephen D. Schery
Physics Department, NMIMT
Mathematics, 1967, The
Nuclear Physics, 1973, The
Recent Activities and Interests:
Since August 2013 I have been a principal scientist (part time) with AerospaceComputing, Inc. assigned to work for NASA at the NASA/Ames Experimental Aerophysics Branch, Moffett Field, CA. Previously I had been an Ames Associate with this same branch. I continue to help with a number of projects related to fluid dynamics and wind tunnel testing.
I helped with the instrumentation for the turbine propulsion simulators (TPS) that will be used with new models of blended-wing aircraft designs to be tested at Langley, Virginia. This is part of NASA's Environmentally Responsible Aviation research program. Our engineering group won a NASA award for tests conducted at the Ames 40 ft by 80 ft wind tunnel.(blend).
Before the TPS project I helped aerospace engineer Jay Panda put together and test a laser system to study high-frequency density fluctuations, temperature, and air velocity (through the Doppler shift) generated by shock waves and supersonic jets using molecular Rayleigh scattering from air. There are many technological hurdles to overcome, such as reducing the interference of non-Rayleigh scattering from aerosol particles in wind tunnel air, but we made good progress. Some early results were reported in Panda and Schery, 2014. If this testing approach can be perfected, it would help with measurements in wind tunnels under extreme conditions (supersonic wind, shock waves, etc.) where it is difficult to make measurements with in-situ mechanical sensors.
I continue to work with projects involving measurement of acoustic emissions from aerodynamic shapes subject to air flow. Tests typically involve a phased array of microphones to take acoustic "pictures" of aircraft models in wind tunnels. These "pictures" can be used to identify sources of external noise from aircraft with an objective of reducing the noise through revised designs or operating procedures. Our larger arrays can have diameters greater than three meters and can contain more than 80 microphones. For signal processing the microphones must be carefully mapped in situ in three dimensions, a task difficult to accomplish with standard laboratory hardware over such large dimensions. As an alternative, I have been working on inexpensive and convenient photogrammetric techniques and software to accomplish the mapping using standard camera images taken from several angles. Initial results are encouraging.
Our acoustic arrays and controlling software are first tested in a laboratory, non-wind-tunnel environment. One common diagnostic product is a video file in which optical and acoustic images are superimposed. The interpretation of the acoustic part of such files can involve consideration of such things as reflection and sidelobe artifacts (related data-processing issues arise when processing radio telescope images from antenna arrays). Examples of such video files can be seen in the following clips: (wmv1) and (wmv2). I am a co-author of a conference paper describing use of this type of equipment to characterize the acoustic background of one of NASA/Ames's wind tunnels. (AIAA)
In June 2009 I attended a technical meeting on "Sources and Measurements of Radon and Radon Progeny Applied to Climate and Air Quality Studies" at Vienna, Austria, sponsored by the International Atomic Energy Agency (IAEA) and the World Meteorological Organization (WMO). I chaired the session on "Radon Exhalation: Measurements and Modelling" and helped with preparation of the report, which became available in 2012 (IAEA 2012).
In September 2010 I gave a paper "Variation of natural radon flux over the earth's surface: a 2010 update" at the 6th International Conference on Protection against Radon at Home and at Work, Prague, Czech Republic. I also co-chaired the session on "Radon: Information Carrier, Radonometry, and Tracer Gas."
In April 2010 I received a 2010 NASA Ames Sustainability Award for design and construction of a filtration system for the Fluid Dynamics Lab's water channel facility. This filtration system removes tracer dye from the channel after it passes over an object of study and circumvents frequent changes of the entire water reservoir. An estimated 30,000 gallons of water per year is saved.
In cooperation with the Albuquerque Soaring Club, I designed and built a sensor that measures tow rope tension when a glider is towed aloft by a tow plane. I have logged tension data (1 and 2) and have analyzed factors controlling tension excursions and resonances. Also on the glider front, an article of mine dealing with strategies for minimizing cross-country flight time in the presence of a prevailing wind was published in Soaring Magazine in 2012 (Schery 2012). My current glider activities center on flying a Carat A motor glider which I keep in California.
I have written a book on radioactive aerosols, which is now available (Kluwer Academic Publishing, now Springer) in both printed and electronic versions. I continue to follow research in aerosol science.
In my interaction with younger scientists, and work as a reviewer, I sometimes find that older papers not readily available in electronic versions are being missed in literature reviews. This situation can lead to researchers unnecessarily "re-inventing the wheel." Some of my own work on environmental thoron and transpiration of radon from vegetation sometimes seems to fall in this category. These observations prompt me in this web page to provide a list of all my publications, for those who may be interested, starting with the very earliest. (pubs)
Selected Publications and Presentations:
S. D. Schery and M. A. Wasiolek, Modeling Radon
Flux from the Earth's Surface, in RADON AND THORON IN THE HUMAN ENVIRONMENT,
World Scientific Publishing,
S. D. Schery, P. T. Wasiolek, B. M. Nemetz, F. D. Yarger, and S. Whittlestone, Relaxed Eddy Accumulator for Flux Measurement of Nanometer-Size Particles, Aerosol Science and Technology, 28, 1998, 159-172.
S. D. Schery, UNDERSTANDING RADIOACTIVE AEROSOLS AND THEIR MEASUREMENT, Kluwer Academic Publishers (now Springer), Dordrecht, 2001.
S. D. Schery and
S. D. Schery and S. Huang, Progress in Estimating the Area of the Earth's Land Surface as a Function of Scale, Eos. Trans. AGU, 87(52), 2006, Fall Meet. Suppl., Abstract NG43D-1771. (poster)
S. D. Schery, Variation of Natural Radon Flux over the Earth's Surface: a 2010 Update, 6th International Conference of Protection against Radon at Home and at Work, Prague, Czech Republic , 13-17, September 2010. (power point)
B. T. Costanza, W. C. Horne, S. D. Schery, and A. T. Babb, Aeroacoutic Characterization of the NASA Ames Experimental Aero-Physics Branch 32- by 48- Inch Subsonic Wind Tunnel with a 24-Element Phased Microphone Array, 17th AIAA/CEAS Aeroacoustics Conference, Portland, Oregon, 2011. (AIAA 2011)
S. D. Schery, Round Trip Travel Time in a Cross Wind, Soaring Magazine, 76, January, 2012, 40-42.
IAEA, Sources and Measurements of Radon and Radon Progeny applied to Climate and Air Quality Studies, STI/PUB/1541, IAEA, Vienna, 2012, ISBN 92-0-123610-4, http://www.iaea.org/books.
J. Panda and S. Schery, Molecular Rayleigh Scattering to Measure Fluctuations in Density and Temperature in Low Speed Heated wind Tunnel Flows, AIAA 2014-2529, 30th AIAA Aerodynamic Measurement Technology and Ground Testing Conference, Atlanta, Georgia, 2014 (arc.aiaa.org/doi/ abs/10.2514/6.2014-2529).
NASA phone: 650-604-0741