Green Scheduling of Jobs and Flexible Periods of Maintenance in a Two-Machine Flowshop to Minimize Makespan, a Measure of Service Level and Total Energy Consumption
Table 1
The notation used to formulate the problem.
Indices
Indices of jobs
Index of machines
Index of processing speeds
Parametres
Number of jobs
Processing speed factor; s = 1, 2, 3 for fast, normal, and slow speeds, respectively
Sequence-dependent setup time for changing from job i to job i′ on machine j (for i = i′, sti,i,jdenotes the setup time for job I if it is the first job in the sequence)
Time required to perform preventive maintenance (PM) on machine j
Conversion factor for processing speed s
Conversion factor for idle time on machine j
Power of machine j
The common power, which is consumed by auxiliaries equipment and facilities
A very large number (set to 1,000,000)
Decision variables
Completion time of job i on machine j
Setup off set for job i on the second machine (in case i is the first job in the sequence)
Idle time on machine j
The makespan, the completion time of the last job on the last machine
