How best to schedule
production work against the likelihood of a machine breakdown is
being studied at The Hong Kong Polytechnic University.
of so-called preemptive-repeat work loss is in metal refining, said
Principal Investigator Dr Zhou Xian. The raw material must
reach a specified temperature to obtain desired purity. If the process
is interrupted by a power outage, the material cools rapidly, work
done prior to the breakdown is lost and the process must start again.
Zhou and his researchers are tackling the problem theoretically
as well as numerically, to determine optimum scheduling of different
jobs under various criteria against the uncertainties of random
know it makes sense to schedule the shortest jobs first, he
said. This way we can reduce the waiting time for subsequent
jobs and therefore reduce proportional costs for items like inventory
costs and factors such as penalties due to late delivery of work
are also built into the formulas.
Dr Zhou: We havent limited the research to a particular
process but were coming up with analytical solutions for certain
situations and algorithms to work out optimal schedules.
breakdowns are more difficult to analyse than preemptive-resume
models where work is not lost because more factors are involved,
said Dr Zhou.
Dr Zhou Xian : firstname.lastname@example.org