Unit operations, control production scheduling

Because of the batchwise nature of electronic materials processing and the long process sequences, a supervisory system is essential. This system collects information on the state of the system gives status of work in progress schedules work based on process priorities, product requirement, equipment readiness, and materials availability and controls product and raw material inventories. Materials handling concerns the physical movement of wafers through the fabrication line via various mechanical means [32] and is therefore primarily a mechanical engineering problem. The control of the individual unit operations and the incorporation of local control functions in... 

The Mizushima Oil Refinery of Japan Energy Corporation first implemented a high conversion operation of vacuum residue, versus a constant desulfurization operation, in the commercial residue hydrodesulfurization unit equipped with fixed-bed reactors, to produce more middle distillates as well as fuel oil with lower viscosity. The catalysts will be replaced when the sulfur content in the product oil reaches the allowable limit. Since we have believed that an increase in the residue conversion decreases the catalyst activity by coke deposition, we have been interested in controlling the coke deactivation to maximize the residue conversion during a scheduled operating period. 

Performance analysis Provide up-to-the-minute reporting of actual manufacturing operations results, along with comparisons to past history and expected results. Performance results include such measurements as resource utilization, resource availability, product unit cycle time, conformance to schedule, and performance to standards. Performance analysis may include SPC/ SQC analysis, and may draw from information gathered by different control functions that measure operating parameters. 

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