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OUTLINE

OUTLINE. Questions? Did you hear or notice anything since last class that has to do something with this class? New Homework Scheduling General Job Shops Quiz on Wednesday. More definitions. Technological Constraint = Routing= Process Plan=

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OUTLINE

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  1. OUTLINE • Questions? • Did you hear or notice anything since last class that has to do something with this class? • New Homework • Scheduling General Job Shops • Quiz on Wednesday

  2. More definitions • Technological Constraint = Routing= Process Plan= • The order in which a job must be processed through machines (servers, agents, etc.) • General Job Shop – Any facility through which jobs are processed and all jobs do not have the same Technological Constraint • Operation – the processing of a job on one of the machines on which it has to be processed • Time Tabling – creating a schedule by placing the operations of a job into a Gantt chart

  3. Time Tabling Example

  4. Kinds of scheduling • Semiactive - process each job as soon as it can be (slide to the left on the Gantt chart) • Active - No operation can be started earlier without delaying some other operation • Non-delay - no machine is kept idle • Non-feasible - does not meet Technological Constraints • Number of possible schedules (including non-feasible ones) = (n!)m • Where n = number of jobs, m= number of machines

  5. Optimality • Since for any given problem there are a countable number of possible schedules (as long as we do not allow preemption or unnecessary delays) there must be an optimum (or optima) because we can (theoretically) compare all possible schedules and select the best one • If we look at the space that contains our schedules and attempt to locate the optimum we find that:

  6. Optimality (continued) • Optimal all possible feasible Active semi active non - delay

  7. Equivalent measures • Two measures are equivalent if a schedule optimal with respect to one is also optimal with respect to the other and vice versa. • Cbar, Fbar, Lbar are equivalent • Note that a schedule optimal to Lmax is optimal with Tmax, but not vice versa • The choice of measure depends on the circumstances

  8. General Job Shop Example

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