What are basic scheduling problems?
The basic form of the problem of scheduling jobs with multiple (M) operations, over M machines, such that all of the first operations must be done on the first machine, all of the second operations on the second, etc., and a single job cannot be performed in parallel, is known as the flow-shop scheduling problem.
What are the assumptions in flow shop scheduling?
In order to get closer to the actual conditions of the problem, some realistic assumptions including non-permutation scheduling, learning effect, multiple availability constraints, and release times are considered.
What is Flexible Job Shop Scheduling?
The flexible job shop scheduling problem (FJSP) is a generalization of the classical job shop scheduling problem that allows to process operations on one machine out of a set of alternative machines. The FJSP is an NP-hard problem consisting of two sub-problems, which are the assignment and the scheduling problems.
What is flow shop scheduling with example?
Flow shop scheduling is a special case of job scheduling where there is strict order of all operations to be performed on all jobs. Solution methods of Flow shop scheduling are Branch and Bound, Dynamic programming, Heuristic algorithm and Meta-heuristics.
What is the objective of flow shop scheduling?
The primary concern of flow shop scheduling is to obtain the best sequence, which minimizes the makespan, flow time, idle time, tardiness, etc. In this work, makespan and total flow time of the jobs are considered for minimization.
Which is an objective function of job shop scheduling?
Objective function can be to minimize the makespan, the Lp norm, tardiness, maximum lateness etc. It can also be multi-objective optimization problem. Jobs may have constraints, for example a job i needs to finish before job j can be started (see workflow ).
What is the disjunctive graph for job shop scheduling?
The disjunctive graph is one of the popular models used for describing the job shop scheduling problem instances. A mathematical statement of the problem can be made as follows: be two finite sets. On account of the industrial origins of the problem, the are called jobs .
Are there any variations of the flexible job shop problem?
Many variations of the problem exist, including the following: Machines can have duplicates (flexible job shop with duplicate machines) or belong to groups of identical machines (flexible job shop). Machines can require a certain gap between jobs or no idle-time.
How is scheduling efficiency defined for a schedule?
Scheduling efficiency can be defined for a schedule through the ratio of total machine idle time to the total processing time as below: is the number of machines. Notice that with the above definition, scheduling efficiency is simply the makespan normalized to the number of machines and the total processing time.