An Analytical Look at Spam
I am writing this manifesto mainly because I’m angry, but also because I like to solve problems. Since June 20, 2001, I have been unfortunate enough to receive 402 spam messages (stat date: July 17, 2001). This is ridiculous. Hopefully, my efforts to bring an engineering prospective to the spam problem will one day result in the end of spam’s chokehold on humanity!
Read more...PM2.5 Design Concentrations in High Background Regions
Fine particulate matter is frequently becoming the permit limiting air pollutant in modeling compliance demonstrations. High background concentrations of particulate matter less than 2.5 microns in aerodynamic diameter (PM2.5) in many parts of the country present air quality permit modeling challenges for National Ambient Air Quality Standards (NAAQS) compliance demonstrations. An examination of PM2.5 24-hour average background concentrations and AERMOD model predicted concentrations for a proposed facility was conducted to investigate the meteorological events underlying the concentration distributions. Regional transport rather than local sources appeared to dominate the observed fine particulate concentrations. Predicted concentrations from the proposed source were strongly influenced by the complex terrain setting of the facility. High predicted concentrations did not temporally correspond to high observed concentrations; however, it is not fully protective of NAAQS to evaluate only high predicted concentration events. High observed concentration events played a more significant role in establishing the design concentration. Further, EPA’s “Guideline on Air Quality Models” approach for determining background concentrations may not be adequately protective of the NAAQS. For this reason, it was necessary to develop an alternative compliance demonstration approach and obtain regulatory agency buy-in on the technique.
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