In the job shop scheduling problem (JSP), a set of N jobs = {J1, J2, . . . , JN} is to be processed on a set of m machines M = {1, 2, . . . ,m}. Each job requires a sequence of operations that must be accomplished according to its manufacturing process Ji = {Oi1, Oi2, . . . , Oim}. Operation Oij requires a processing time of pij time units on machine Mij ∈ M . Each machine can perform at most o...

Hybrid algorithm based on Particle Swarm Optimization (PSO) and Simulated annealing (SA) is proposed, to solve Flexible Job Shop Scheduling with five objectives to be minimized simultaneously: makespan, maximal machine workload, total workload, machine idle time & total tardiness. Rescheduling strategy used to shuffle workload once the machine breakdown takes place in proposed algorithm. The hy...

We consider the ordinary NP-hard two-machine flow shop problem with the objective of determining simultaneously a minimal common due date and the minimal number of tardy jobs. In [S. S. Panwalkar, C. Koulamas, An O(n) algorithm for the variable common due date, minimal tardy jobs bicriteria two-machine flow shop problem with ordered machines, European Journal of Operational Research 221 (2012),...

This paper describes an order release and loading technique, which considers the routing as well as the machine flexibility of a modern job shop production. The workload control approach involves three steps. In a first step 'lead orders', i.e. urgent production orders that are either processed on a known bottleneck or are of high value, are identified. Afterwards transfer batches of the lead p...

In the first part of this paper we show that the Shortest Common Superstring problem is NP-complete even if all strings are of the simple form 10plOq, p,q E N. This result closes the gap left between the polynomial cases where all strings are of the form Op104 or all strings are of the form lop1 and NP-complete cases when strings have a more complicated structure. In the second part of the pape...