Stephen D. Schery
Physics Department, NMIMT
Mathematics, 1967, The
Nuclear Physics, 1973, The
Emeritus Activities and Interests while working at NASA:
From August 2013 until April 2021 I was a principal scientist (part time) with AerospaceComputing, Inc. working for NASA at the NASA/Ames Experimental Aerophysics Branch, Moffett Field, CA.
I helped with the instrumentation for the turbine propulsion simulators (TPS) to be used with new models of blended-wing aircraft designs to be tested at Langley, Virginia. This was 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. Some initial results were reported in Panda and Schery, 2014. If this testing approach can be perfected it will 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.
More recently at NASA I worked with projects involving measurement of acoustic emissions from aerodynamic shapes subject to air flow. Tests typically involved 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. Larger arrays had diameters greater than three meters and contained more than 80 microphones. For signal processing the microphones were carefully mapped in situ in three dimensions, a task difficult to accomplish with standard laboratory hardware over such large dimensions. As an alternative, I worked on inexpensive and convenient photogrammetric techniques and software to accomplish the mapping using standard camera images taken from several angles.
The acoustic arrays and controlling software were 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) Our NASA acoustics group also published a paper on the related issue of improving the efficacy of acoustic arrays in the wind tunnel environment by the use of screens and foams to suppress unwanted background noise (Horne et al., 2021).
During this same NASA period I continued to follow research related to atmospheric radon and its decay products. In January 2021 I gave a talk to the Experimental Aerophysics Branch at NASA/Ames entitled “Transport of Radon Gas on the Surface of the Earth, Moon, and Mars.”
Earlier Emeritus Activities:
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 work was done while a visiting AMES associate. 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 in the area of glider research, 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).
I have written a book on radioactive aerosols, which is now available (Kluwer Academic Publishing, now Springer) in both printed and electronic versions, and continue to follow research in this field.
Publications and Presentations:
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 with this web page to provide a list of all my publications, for those who may be interested, starting with the very earliest. (pubs) A selection from this list of some of the more recent (after 1997) publications and presentations follows.
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).
W. Horne, N. Burnside, S. Schery, G. Podboy, C. Bahr, D. Stead, and W. Humphreys, Effects of Resistive Windscreens and Foam Inserts on the Acoustic Response of an In-Flow Phased Microphone Array, 2021, AIAA Scitech 2021 Forum, https://doi.org/10.2514/6.2021-0217