No Wait Pattern

Intent

When a number of jobs are to be processed on a set of machines, the No Wait pattern forces that jobs are not allowed to wait between operations.

Motivation

Sometimes it is desirable to ensure that jobs do not wait on buffers between machines and instead move on directly to the next machine. For example, if a job is being heated on one machine to then be worked on at the next machine, the job must move directly on to the next machine for processing while it is still sufficiently hot.

Applicability

Necessary conditions: Flexible Flow Shop Pattern or Job Shop Pattern
Sufficient conditions: The necessary conditions and for every job there is no waiting time between two consecutive operations in the job operations sequence, so for any $j\in J_E$ and any $i \in \{2,\dots, |ops^p(j)|\}$ : $\texttt{\#}_{\mbox{end}}(op^p_{i-1}(j)) = \texttt{\#}_{\mbox{start}}(op^p_{i}(j)).$

Participants

A set of jobs consisting of operations, and a set of machines.

Collaborations

For any job, the finish time of an operation on a machine must be equal to the start time of the next operation of the job.

Diagram

Gantt chart showing two jobs displaying the no wait pattern:

Consequences

This pattern implies the Permutation Pattern.

Modelling variants

Note: As the Permutation Pattern (for (Flexible) Flow Shop) is implied by the modelling variants of the No Wait Pattern, there is no need to also include the Permutation Pattern modelling variant in the model
(1) OPL for Cplex CP with Job Shop Pattern Cplex modelling variant Download
(2) OPL for Cplex CP with Flexible Flow Shop Pattern Cplex modelling variant Download
(3) OPL for Cplex CP with Flow Shop Pattern Cplex modelling variant Download
(4) MiniZinc with Job Shop Pattern MiniZinc modelling variant Download
(5) MiniZinc with Flexible Flow Shop Pattern MiniZinc modelling variant
Download
(6) MiniZinc with Flow Shop Pattern MiniZinc modelling variant
Download

Forces

Scheduing Problem Pattern, Permutation Pattern

Enables

Compatible with

Machine Setup Pattern, Distinguishable Resources Pattern, Indistinguishable Resources Pattern