In the past, we have demonstrated how fuzzy concepts can easily be used in the Johnson algorithm to manage uncertain scheduling on two-machine flow shops. This paper extends application to fuzzy flow shops with more than two machines. A new fuzzy heuristic flow-shop scheduling algorithm (the fuzzy Palmer algorithm) is then designed since optimal solutions seem unnecessary for uncertain environm...

This paper studies no-wait flowshop scheduling problems to minimize total tardiness. This paper mathematically formulates the problem as an effective mixed integer linear programming model. Moreover, this paper proposes solution methods based on variable neighborhood search and simulated annealing algorithms. Besides, some well-known heuristics of classical flow shops are adapted to the case of...

This paper considers a two-stage flexible flowshop scheduling problem with no waiting time between two sequential operations of a job and no idle time between two consecutive processed jobs on machines of the second stage. We show its complexity and present a heuristic algorithm with asymptotically tight error bounds. © 2004 Elsevier B.V. All rights reserved.

In this paper we study polynomial time approximation schemes (PTASes) for the no-wait job shop scheduling problem with the makespan objective function. It is known that the problem is MaxSNP-hard in the case when each job is allowed to have three operations or more. We show that if each job has at most two operations, the problem admits a PTAS if the number of machines is a constant (i.e., not ...

Predicting how changes to the urban environment will affect town centre vitality, mediated as pedestrian flows, is important for environmental, social and economic sustainability. This study is a longitudinal investigation of before and after urban environmental change in a town centre and its association with vitality. The case study baseline is Cardiff town centre in 2007, prior and after maj...