This paper discussed the scheduling problem of outpatients in a radiology center with an emphasis on priority. To more compatibility to real-world conditions, we assume that the elapsed times in different stages to be uncertain that follow from the specific distribution function. The objective is to minimize outpatients’ total spent time in a radiology center. The problem is formulated as a fle...

Flexible job shop scheduling problem, is an extension of the classical job shop scheduling problem. In Flexible job shop scheduling problem, there are more than one machine with the same features for the same purpose. The problem can be defined as appointing the jobs to the machines (assignment) and ordering the jobs at each machine (sequencing) to serve the desired purpose. Multi-objective fle...

this paper presents a new mathematical model for a bi-objective job shop scheduling problem with sequence-dependent setup times that minimizes the weighted mean completion time and the weighted mean tardiness time. for solving this multi-objective model, we develop a fuzzy multi-objective linear programming (fmolp) model. in this problem, a proposed fmolp method is applied with respect to the o...

This paper considers a scheduling problem in which a single operator completes a set of n jobs requiring operations on two machines. The operator can perform only one operation at a time, so when one machine is in use the other is idle. After developing general properties of optimal schedules, the paper develops e cient algorithms for minimizing maximum lateness. The algorithm has time complexi...

Uncertainty plays a significant role in modeling and optimization of real world systems. Among uncertain approaches, fuzziness describes impreciseness while for ambiguity another definition is required. Vagueness is a probabilistic model of uncertainty being helpful to include ambiguity into modeling different processes especially in industrial systems. In this paper, a vague set based on dista...

In the stochastic online scheduling environment, jobs with unknown release times and weights arrive over time. Upon arrival, the information on the weight of the job is revealed but the processing requirement remains unknown until the job is finished. With the objective of minimizing the total weighted completion time, various asymptotically optimal algorithms have been proposed for the online ...

We investigate the multiprocessor multi stage open shop scheduling problem In this variant of the open shop model there are s stages each consisting of a number of parallel identical machines Each job consists of s operations one for each stage that can be executed in any order The goal is to nd a non preemptive schedule that minimizes the makespan We derive two approximation results for this N...

The two machine routing open shop being a generalization of the metric TSP and two machine open shop scheduling problem is considered. It is known to be NP-hard even for the simplest case when the transportation network consists of two nodes only. For that simplest case it is known that the optimal makespan for any instance belongs to interval [R̄, 6 5 R̄], there R̄ is the standard lower bound. We...

In this paper, we consider the problem of scheduling n jobs on m machines in an open shop environment so that the sum of completion times or mean flow time becomes minimal. For this strongly NP-hard problem, we develop and discuss different constructive heuristic algorithms. Extensive computational results are presented for problems with up to 50 jobs and 50 machines, respectively. The quality ...