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When we did traditional research of DBR, we assumed that Identical Parallel Machines Environment was used to do analysis. Currently the constrain of assets and development of technology, the different machines produce same product will get the different results of work time and precision. The condition is that different machines will be used in one work station to meet the needs of different processes and products.
For example, the different machines are used in same test operation doing different products testing criteria to meet the different customers'' quality needs which exists in the Semiconduction Testing Factory. The condition was named Non-identical Parallel Machines Environment. We face two problems in this environment: (1)varieties of customers and products make us hard to predict combinations of machine set in CCR. If we consider all combinations, the system will be huge. (2)In case of same machine is used in many different machine groups to produce different products, this machine capacity will be over loaded and induce different products, this machine capacity will be over loaded and induce unbalance in production flow. Now schedule programs cannot solve these two problems in Nonidentical Parallel Machines. This research mentions both Drum in Non-identical Parallel Machines with reentrant and without reentrant to consider the drum processes reentrant under the Non-identical Parallel Machines Environment in order to extend the adaptability of the DBR.
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