Problem type-aspects of scheduling , Mechanical Engineering

Problem Type

Aforementioned illustration relates to the class of non-cyclic scheduling problems characterized via the subsequent features.

(a) The Flexible Manufacturing System consists of M stations (workplaces, machines) all of that can process at mainly one operation at a time,

(b) The inventory that may change at some time contains N jobs along with termed earliest possible beginning times and due dates,

(c) A job is a sequence of operations along with precedence constraints that is most operations can only be begun if one or some preceding operations have been finished.

                            Table no.2 (b): Due Dates Distributions for Situation E-H

Situation A : Case 2, 30% late jobs under the FIFO scheduling rule

Demanded Throuhput Time       %          of

Parts

 

240                            5

 

480                            5

 

720                            5

 

960                            35

 

1200                          50

 

Average Throughput Time: 1008 min

 

Demanded/achieved flow factor: 1.20

 

Situation A : Case 2, 50% late jobs under the FIFO scheduling rule

Demanded Throughput Time     %          of

Parts

 

240                            5

 

480                            10

 

720                            35

 

960                            27

 

1200                          23

 

Average Throughput Time: 847 min

 

Demanded/achieved flow factor: 1.00

 

Situation A : Case 2, 70% late jobs under the FIFO scheduling rule

Demanded Throuhput Time       %          of

Parts

 

240                            19

 

480                            25

 

720                            31

 

960                            15

 

1200                          10

 

Average Throughput Time: 653 min

 

Demanded/achieved flow factor: 0.78

 

Situation A : Case 2, 85% late jobs under the FIFO scheduling rule

Demanded Throuhput Time       %          of

Parts

 

240                            30

 

480                            45

 

720                            15

 

960                            5

 

1200                          5

 

Average Throughput Time: 504 min

 

Demanded/achieved flow factor: 0.60

 

(d) For all operation, this is identify that on which stations (one or more) this can be represented and how long this acquires (containing transportation times); these durations  are  supposed  to  be  independent of  the  scheduling deterministic and policy  ,

(e) Operations which have been begun but cannot be interrupted (non-preemptive scheduling), and

(f) The idle times among the operations are not limited, neither are the buffers opposite the stations or at the output.

Consequently the major restriction is the capability of the stations. Another limitation is assumed to be of secondary significance. They may be shown via the earliest possible starting times of the operations or contained in the operation times, for instants: via adding a constant average transportation delay. Obviously, the transportation system can be integrated via adding transport operations to the work plans and explaining one or more resources that provide transport and have to be assigned as well. The only limit implied through the  assumptions made  is  that  the  resource  uses  times  are  independent of  the processing sequences.

In the test difficulty, the options on which station an operation is presented are only amongst identical stations.  Hence,  for  each  operation  there  is  merely  one  value  for  its (nominal)  net  operation  time.  However, this assumption is not essential for the algorithms discussed afterward.

Posted Date: 3/5/2013 7:23:25 AM | Location : United States







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