A Two-Stage Layered Mixture Experiment Design for a Nuclear Waste Glass Application (Part 2)

• Activity Number: 23
• Type: Contributed
• Date/Time: Sunday, August 3, 2003 : 2:00 PM to 3:50 PM
• Sponsor: Section on Physical and Engineering Sciences
• Author(s): Scott K. Cooley*+ and Gregory F. Piepel and Hao Gan and Ian Pegg and Wing Kot
• Companies: Battelle-Pacific Northwest Division and Battelle, PNNL and Catholic University of America and Catholic University of America and Catholic University of America
• Keywords: layered design ; mixture experiment ; optimal experimental design ; nuclear waste glass

Abstract

Part 1 describes the first stage of a two-stage experimental design to support waste glass property-composition modeling. Each stage used a layered design having an outer layer, an inner layer, a center point, and some replicates. However, the design variables and constraints defining the layers were defined differently for the second stage than for the first. The first stage involved 15 components, all treated as mixture variables. The second stage involved 19 components, with 14 treated as mixture variables and 5 treated as nonmixture variables. For each second-stage layer, vertices were generated, and optimal design software was used to select alternative subsets of vertices and calculate design optimality measures. A model containing 29 partial quadratic mixture terms plus 5 linear terms for the non-mixture variables was the basis for the optimal design calculations. Predicted property values were plotted for the alternative subsets of second-stage vertices and the first-stage design points. Based on the optimality measures and the predicted property distributions, a "best" subset of vertices was selected for each layer of the second-stage to augment the first-stage design.