Control for a production line that queues work-in-process (WIP) prior to a re-entrant bottleneck processing node, such as a photolithography device in a semi-conductor fabrication line. For each WIP, a determination is made as to whether a cleared trajectory is available through all processing nodes...http://www.google.com.hk/patents/US6714830?utm_source=gb-gplus-share專利 US6714830 - Push-type scheduling for semiconductor fabrication
