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The rough model is used along with feature knowledge to drive a coordinate measuring machine so that data can be refined . PARCA began in 1993 with the primary goal of measuring and understanding the mass balance of the Greenland Ice Sheet . For example , if you had people take a test measuring their reaction times and you were interested in looking at the differences between people who had fast reaction times and those with slow reaction times , you could call the first group the " fast reaction time group " and the second the " slow reaction time group . A so-called torsion balance , which depends on the twisting of a wire or thread , is employed for weighing , but the term is commonly used to indicate a device for measuring minute electrical and magnetic forces . After planting , a seasonal ground water testing program began that monitored the progress of remediation by measuring the concentration of the 10 predominant PAHs in the contaminant plume : naphthalene , acenaphthylene , acenaphthene , fluorene , phenanthrene , anthracene , fluoranthene , pyrene , chrysene , and benzo ( b ) fluoranthene .