tailieunhanh - The Design of Manufacturing Systems Part 6

Tham khảo tài liệu 'the design of manufacturing systems part 6', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | the coverability of the safe space Ss by the policy-admissible subspace S P . More formally consider the polynomial-kernel policy defined by property H and let 5 H s G 5 H s is TRUE that is the policy admissible subspace. Then a viable policy efficiency measure is provided by the ratio Ỉ qyr Psi where IP denotes the cardinality number of set S. Because of the typically large size of the S H and Ss subspaces their explicit enumeration will not be possible and therefore we must resolve simulation and statistical sampling techniques. Such a technique known as the co-space simulation technique is developed in Reference 62 . Briefly this approach recognizes that the set of safe states of a given SU-RAS Q corresponds to the reachability set of a co-system Q which is defined from the original RAS Q by reversing its job routes. Hence the operation of the cosystem Q is simulated until a sufficiently large sample of states is obtained. According to the previous remark this sample set consists of safe states of the original system. In continuation the condition H defining the evaluated DAP is applied on the extracted sample set and the portion of the sample states admitted by the policy is determined. This portion expresses the policy coverability of the extracted sample set and constitutes a point estimate for index I. Application of this technique to the polynomial-kernel DAPs of Section and experimental evaluation results can be found in References 58 59 and 62 . In the rest of this section we discuss some properties of polynomial-kernel DAPs which can be used to enhance the operational flexibility of these policies when implemented on any given FMS configuration. Policy Disjunctions and Essential Difference The first way to improve the efficiency of an FMS structural controller employing polynomial-kernel DAPs with respect to the metric of Eq. is based on the following proposition. Proposition Given two conditions H1 and H2 defining correct .