eprintid: 157
rev_number: 4
eprint_status: archive
userid: 6
dir: disk0/00/00/01/57
datestamp: 2008-10-07
lastmod: 2015-05-29 19:48:21
status_changed: 2009-04-08 16:54:56
type: report
metadata_visibility: show
item_issues_count: 0
creators_name: Palacios, Luz
creators_name: Aggarwala, Rita
contributors_name: Agyekum, Eric
contributors_name: Amariei, Andreea
contributors_name: Caughlin, Brenda
contributors_name: Cheng, Jie
contributors_name: Huszti, Ella
contributors_name: Jungic, Veselin
contributors_name: Ngembo, Emmanuel
contributors_name: So, Grace
contributors_name: Wiebe, Paul
title: Optimal Control for Multi-variable Problems
ispublished: pub
subjects: materials
subjects: other
studygroups: ipsw3
companyname: Chemex Laboratories
full_text_status: public
abstract: Chemex Laboratories measures concentrations of various minerals in land samples provided by their clients. The problem presented by Chemex is that they would like to be able to detect when their measurement apparatus needs re-calibration due to a shift in process parameters, so as to minimize rework.

Three very contrasting approaches to the problem were taken during the workshop. They are: considering the process as a Markov Chain; use of Bayesian Belief Networks; and Multivariate control chart implementation. Preliminary data analysis for data provided by Chemex was also performed in order to initially assess some of the models considered.
problem_statement: Analytical methods where many elements are determined simultaneously present special difficulties in quality control. The use of individual control charts for each variable (element) is generally not effective due to the combinative aspect of the variation.
date: 1999
date_type: published
pages: 11
citation:   Palacios, Luz and Aggarwala, Rita  (1999) Optimal Control for Multi-variable Problems.  [Study Group Report]     
document_url: http://miis.maths.ox.ac.uk/miis/157/1/quality_control.pdf