Stephen D. Schery
Professor Emeritus
Physics Department, NMIMT
B. S.,
Mathematics, 1967, The
M. S.,
Physics, 1970,
Ph. D.,
Nuclear Physics, 1973, The
|
Recent
Activities and Interests: Since January 2008 I have been a visitor at the NASA/Ames Experimental Aerophysics Branch. I am helping with a number of projects related to fluid flow dynamics and wind tunnel testing. One major project involves designing and testing a new anemometer system for ships that avoids protruding vanes or cups by monitoring the dynamic pressure at a number of small pressure ports about the circumference of the ship. Unraveling the influence of pascal-scale pressure variations at these ports, unrelated to wind speed and direction, is one of many interesting challenges. In the earth sciences direction, a continued interest of mine is a study of the area of the earth's land surface as a function of scale. My interest was prompted by the following question. Suppose one wants to make a global estimate of an exchange process at the air-land interface which is to be calculated by multiplying an average flux density (specified in the form "physical quantity of interest" per unit area per unit time) by the area of the earth's land surface. If the flux density has associated with it a certain length scale for which it is applicable (for example, a diffusion length), what area should be used for the earth's land surface? Another way of looking at this question is the following. Suppose one wishes to cover the earth's land surface with a coating that has a specified thickness (perhaps many meters thickness for the purposes of this Gedanken exercise!). What area should be used with the specified thickness to calculate the volume of the coating material needed? Thin coatings will have to go up and down with the bumps and roughness elements of the surface whereas thicker coatings can straddle many uneven features. This subject is a two-dimensional analog of the well-known fractal mathematics problem of what is the length of the coastline of Great Britain (or any island). The answer depends on the length of the measuring rods used to make the measurement. Shorter rods laid end to end pick up smaller variations in the coastline and give a larger number. Using digital elevation data and some modeling tricks, I have been estimating an average global ratio for the surface land area at a given scale length to the corresponding area for a pure horizontal surface. So far, the smallest scale for which I have a result is a scale length of about 10 m. The estimated ratio in this case is 1.0153 +/- 0.0036. I am really interested in smaller scale lengths,but obtaining global estimates for them is quite challenging. There is a sparsity of suitable global elevation data available at finer grid spacing. Extrapolating results using an approximate fractal dimension is dangerous since, particularly in geophysical applications, the apparent fractal dimension can be different at different scale ranges. Other 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 and the World Meteorological Organization. I chaired the session on "Radon Exhalation: Measurements and Modelling" and am currently helping with preparation of the report, which hopefully will be completed in 2010. In July 2009 I received a Certificate of Appreciation and award from NASA/Ames for design 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, which previously had been required. In cooperation with the Albuquerque Soaring Club, I have 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 am trying to analyze factors controlling tension excursions and resonances. These studies are aimed at better understanding stresses developed during the towing process. They might aid in the development of improved tow ropes and safer operating protocols. I have written a book on radioactive aerosols and continue to follow research in aerosol science. I also try to stay abreast of developments related to mapping the flux of radon and thoron from the soil and oceans.
Selected
Publications: S. D. Schery, S. Whittlestone, K. P. Hart, and S. E. Hill, The Flux of Radon and Thoron from Australian Soils, Journal of Geophysical Research, 94, 1989, 8567-8576. 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, S. Huang, S. D. Schery, R. E. Alcantara, J. C. Rodgers, and P. T. Wasiolek, Influence of Dust Loading on the Alpha-Particle Energy Resolution of Continuous Air Monitors for Thin Deposits of Radioactive Aerosols, Health Physics, 83, 2002, 884 - 891. 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) |
|
|
Nasa phone: 650-604-0741,
Last Revised: