Biomedical subjects

Daniel A Stone

Publications and source records attributed to Daniel A Stone.

3 recordsLinked to original sources

PubMed2006

Validation of the digital opacity compliance system under regulatory enforcement conditions.

U.S. Environmental Protection Agency (EPA) Emission Measurement Center in conjunction with EPA Regions VI and VIII, the state of Utah, and the U.S. Department of Defense have conducted a series of long-term pilot and field tests to determine the accuracy and reliability of a visible opacity monitoring system consisting of a conventional digital camera and a separate computer software application for plume opacity determination. This technology, known as the Digital Opacity Compliance System (DOCS), has been successfully demonstrated at EPA-sponsored Method-9 "smoke schools", as well as at a number of government and commercially operated industrial facilities. Results from the current DOCS regulatory pilot study demonstrated that, under regulatory enforcement conditions, the average difference in opacity measurement between the DOCS technology and EPA Reference Method 9 (Method 9) was 1.12%. This opacity difference, which was computed from the evaluation of 241 regulated air sources, was found to be statistically significant at the 99% confidence level. In evaluating only those sources for which a nonzero visible opacity level was recorded, the

Air Pollutants↗

PubMed2004

Measuring visual opacity using digital imaging technology.

The U.S. Environmental Protection Agency (EPA) Reference Method 9 (Method 9) is the preferred enforcement approach for verifying facility compliance with federal visible opacity standards. Supporters of Method 9 have cited its flexibility and low cost as important technological and economic advantages of the methodology. The Digital Opacity Compliance System (DOCS), an innovative technology that employs digital imaging technology for quantifying visible opacity, has been proposed as a technically defensible and economically competitive alternative to Method 9. Results from the field application of the DOCS at EPA-approved Method 9 smoke schools located in Ogden, UT, Augusta, GA, and Columbus, OH, demonstrated that, under clear sky conditions, the DOCS consistently met the opacity error rate established under Method 9. Application of hypothesis testing on the smoke school data set confirmed that the DOCS was equivalent to Method 9 under clear sky conditions. Under overcast sky conditions, human observers seemed to be more accurate than the DOCS in measuring opacity. However, within the smoke school environment, human observers routinely employ backgrounds other than sky (e.g., trees, telephone poles, billboards) to quantify opacity on overcast days. Under conditions that compel the use of sky as plume background (e.g., emission stacks having heights above the tree line), the DOCS appears to be a more accurate methodology for quantifying opacity than are human observers.

Air Pollutants↗

PubMed2003

Evaluation of the digital opacity compliance system in high mountain desert environments.

The digital opacity compliance system (DOCS) has been proposed as an alternative to the U.S. Environmental Protection Agency Reference Method 9 (Visual Determination of the Opacity of Emissions for Stationary Sources). The DOCS, which employs standard digital photography to estimate the opacity of visible emissions, was evaluated in a high mountain desert environment located in Weber County, UT. The DOCS recorded an average opacity deviation of 5.28% when applied to black smoke plumes having true opacities in the range of 0-100%, an error rate that was found to be significantly less than 7.5% (allowable error rate for attaining certification under Method 9). In contrast, results from estimating the opacity of white smoke plumes indicated that the accuracy of the DOCS was less than the Method 9 error rate only in the opacity range of 0-60%, over which the DOCS average opacity deviation was determined to be 6.7%. For the 0-40% opacity range, the DOCS recorded an average opacity deviation of 5.44% and 5.9% for black and white plumes, respectively. Results from the present study suggest that the DOCS has the potential to quantify visible opacity with an error rate that is significantly less than the Method 9 permissible error rate. Although encouraging, it is unclear to what extent the DOCS is affected by climatic conditions other than those encountered in a dry desert environment. Future studies should focus on evaluating the performance of the DOCS under variable weather conditions.

Algorithms↗