Q2. How many buffers/gaps are there between consecutive tasks?
When the λ values are low the objective is mainly focused on minimizing energy, so makespan is higher and therefore, there exists many455buffers/gaps between consecutive tasks.
Q3. What is the reason why the energy reduction is considered a special case?
when λ = 1, it is considered an special case because the makespan in only taken into consideration in the objective function, so many tasks that are not involved in the critical path can be executed at lower speed without worsening the makespan.
Q4. What is the reason why the on/off control framework is not applicable?
For some manufacturing systems, however, it is not possible to turn off machines completely during each of the idle intervals, either because restarting the machines requires a large amount of energy or because frequent on and off switches may damage to the machine com-70ponents.
Q5. How can the authors see the rescheduling process?
it can be observed that the involved machines in the rescheduling process have been accelerated, so the obtained reschedule is not an energy efficient solution.
Q6. What is the main objective of the research on energy-efficient scheduling?
Mouzon et al. (2007) developed several algorithms and a multiple-objective mathematical programming model60to investigate the problem of scheduling jobs on a single CNC machine in order to reduce energy consumption and total completion time.