Читать книгу Statistics and Probability with Applications for Engineers and Scientists Using MINITAB, R and JMP - Bhisham C. Gupta, Irwin Guttman - Страница 19

In this initial phase, an experiment was run in which the roles of three variables were studied: collar screen mesh size (fine, coarse), horizontal screen mesh size (fine, coarse), and flow rate (gpm). At this stage,

1 The experimenters were encouraged by the generally high values achieved for y.

2 Highest values for y were apparently achieved by using a horizontal screen with a coarse mesh and a collar screen with fine mesh.

3 Contrary to expectation, flow rate did not show up as an important variable affecting y.

4 Most important, the experiment was unexpectedly dominated by the values, which measure the flow retreated. These were uniformly very low, with about 0.01% of the flow being returned to the treatment plant and 99.9% leaving the screen for discharge into the river. Although it was desirable that the retreated flow be small, the values were embarrassingly low. As the experimenters remarked, “[T]he horizontal screen produced a solid concentratedry enough to shovel. This represented a waste of effort of concentrating because the concentrated solids were intended to flow from the units.”