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Ch41-I044963.fm Page 197 Tuesday, August 1, 2006 3:54 PM
1, 2006
3:54 PM
Page 197
Tuesday, August
Ch41-I044963.fm
197
197
TABLE 1
OBJECTIVE FUNCTIONS OF HOLONS
Objective fimctions Objective function values
Efficiency S Machining Time / Total Time
Resource
Machining S (Machining Accuracy of Resources -
Holon
Accuracy Required Machining Accuracy of Jobs)
Job Flow Time I (Machining Time + Waiting Time)
Holon Machining Cost S (Machining Cost of Resources)
The following procedures are provided for the job holons to evaluate the objective ftinctions. Let us consider ajob
give the total time after the job holon / is inputted to the HMS and
holon i at time t. It is assumed that JTj., and JQ. t
the machining cost, respectively. If the job holon i selects a candidate resource holon/ (= Rfh,,) for carrying out the
machining process M&, the flow time JTj. M(J) and the machining costs JQ.i+\(j) are estimated by the following
equations.

0)
JCi, +lQ)=JG,+MCO ikl- (2)
As regards the resource holons, the following equations are applied to evaluate the efficiency MEj.,+\(i) and the
machining accuracy MAj.i+\(i), for the case where a resource holon j (= Rn m) selects a candidate job holon / for
carrying out the machining process M&.
(i)= -(ME/. tTTj. t+ T i •T V+W) (3)
MAj., H(i)=MA H+ (4)

where, 77}.,, ME}.,, and MAj. t show the total time after the resource holon/ starts its operations, the efficiency, and
the evaluated value of machining accuracy of the resource holon , j respectively. Eqn. 3 contains the minus sign in
order to evaluate the efficiency as the minimization problem.

The holons may select to wait in the next time period without executing any machining processes. In this case, the
objective ftinctions of the individual holons are evaluated by the following equation.
./WO) = max {JTi.md)} (5)
j=\.—.r
JQ. w(0)=max {JC, M(f)} (6)
J i r
(7)
(8)

where, /and S are the number of candidate resource holons for the job holon /, and the number of candidate job
holons for the resource holon , j respectively. Eqn. 5 to 8 mean that these objective function values are defined by
the worst values of all the candidate resource holons, if they select waiting.

COORDINATION AMONG HOLONS BASED ON MULTI-OBJECTIVE OPTIMIZATION PROBLEM

Pareto Optimal Combination of Holons
After the individual holons evaluate the objective ftinctions, the coordination holon generates all pareto optimal
combinations of the job holons and the resource holons, which carry out the next machining processes. The