PSO for PSBRC 中，決策變數是不是用優先權值來排序的?!
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阿蒙
Jun 22, 2007, 9:06:56 AM6/22/07
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請參照如下的第4頁(262頁)部份內容。我感覺還是以隨機的優先權值來決定工項的順序。而的確它的優先權值是以1小時作單位的，但是只拿一段時間的第一個小格來作排序。如 A3 工項的第一小時如果是 0 的話，那麼它會先拿來排，排定後，就會扣掉 Tw 的格數，如 8 格，那麼下一次排序時，就是拿 A3 第9格的優先權值來作排序。
所以它的方式還是以隨機產生次序後，邊算邊看它是否符合限制式的要求，如果沒有就跳下一個。
Solution-Representation of GA Approach for Solving RCPS
In general, two representation schemes for the RCPS solution are considered when applying GA, such as the permutation-based representation and priority-based (or random key) representation, which have been reviewed by Bean (1994); Chan et al. (1996); and Hartmann (1998). In the permutation-based representation, the location of an activity in the chromosome-represented permutation means the order or sequence this activity is to be scheduled to start. In the priority-based representation, each location or element in the chromosome fixedly represents an activity and the corresponding value of each element means the priority an activity is scheduled to start. Therefore the GA solution scheme for the RCPS is to search for an optimal combination of the priority values for all activities (Lee and Kim 1996).
Solution-Representation of PSO for Solving PSBRC
In this study, the priority-based representation for the GA approach will be adopted to develop the solution-representation for the PSBRC through the particle so as to bridge between the PSBRC and PSO. A preemptive activity ai with duration Di should be assigned Di priority values for the Di units even though not all the Di priority values will be used; the priority value for the first duration unit will be absolutely used to decide the order to start activity ai, while other priority values will be used only when activity ai resumes from the corresponding duration unit after it is interrupted in off-working time. As a non-preemptive activity ai, however, only one priority value is required to decide its scheduling order because the activity duration is not split into multiple duration units. A set of priority values can decide the order to start the activities (including the preemptive and the nonpreemptive activities) or restart the interrupted activities ( i.e., preemptive activities). The constrained resources are also allocated to the competing activities based on the priority values, so that the starting or restarting times of the activities are determined. Therefore a set of priority values actually corresponds to a possible solution to the PSBRC. During the working period, only the priority values of the first duration units for the preemptive activities are compared with the priority values of the non-preemptive activities. When a new working period begins after the break, however, the priority values of the duration units from which the interrupted activities will resume are compared with the priority values for the first duration units of other preemptive activities and the priority values of the nonpreemptive activities.
所以它的方式還是以隨機產生次序後，邊算邊看它是否符合限制式的要求，如果沒有就跳下一個。
Solution-Representation of GA Approach for Solving RCPS
In general, two representation schemes for the RCPS solution are considered when applying GA, such as the permutation-based representation and priority-based (or random key) representation, which have been reviewed by Bean (1994); Chan et al. (1996); and Hartmann (1998). In the permutation-based representation, the location of an activity in the chromosome-represented permutation means the order or sequence this activity is to be scheduled to start. In the priority-based representation, each location or element in the chromosome fixedly represents an activity and the corresponding value of each element means the priority an activity is scheduled to start. Therefore the GA solution scheme for the RCPS is to search for an optimal combination of the priority values for all activities (Lee and Kim 1996).
Solution-Representation of PSO for Solving PSBRC
In this study, the priority-based representation for the GA approach will be adopted to develop the solution-representation for the PSBRC through the particle so as to bridge between the PSBRC and PSO. A preemptive activity ai with duration Di should be assigned Di priority values for the Di units even though not all the Di priority values will be used; the priority value for the first duration unit will be absolutely used to decide the order to start activity ai, while other priority values will be used only when activity ai resumes from the corresponding duration unit after it is interrupted in off-working time. As a non-preemptive activity ai, however, only one priority value is required to decide its scheduling order because the activity duration is not split into multiple duration units. A set of priority values can decide the order to start the activities (including the preemptive and the nonpreemptive activities) or restart the interrupted activities ( i.e., preemptive activities). The constrained resources are also allocated to the competing activities based on the priority values, so that the starting or restarting times of the activities are determined. Therefore a set of priority values actually corresponds to a possible solution to the PSBRC. During the working period, only the priority values of the first duration units for the preemptive activities are compared with the priority values of the non-preemptive activities. When a new working period begins after the break, however, the priority values of the duration units from which the interrupted activities will resume are compared with the priority values for the first duration units of other preemptive activities and the priority values of the nonpreemptive activities.
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