Maximum perishability

The idea of the new approach is to, first, define only one model that includes all constraints - be it shift models, personnel, batch sizes, maximum perishabilities or soft constraints such as costs and values, characteristic numbers or feasibility and optimum of the plan. The case studies will show that the model follows an intuitive representation of the relevant items. Second, the operator based approach makes the overall solution procedure extensible. If one operator gets stuck in a local optimum another operator may help out and could be added at any time. Third, the whole approach works on understandable objects such that at any time during the solution procedure an easy check can be made what happens. 

Often products in the chemical production have a maximum perishability. This has two consequences. The process may not be interrupted longer than the maximum perishability. For example the weekend may cause a long break and as a consequence the quant must start the next week instead of the current week. 

A more complex constraint to meet is the maximum perishability as the maximum time frame within the material produced by a process must be processed by the successor processes. This maximum perishability may even be dependent of the successor process and the predecessor process. Using different storage or tanks the perishability may change dependent on the chosen storage location. 

The band gap figures in Table 5.3 signify the temperature sensitivity of the materials and the practical ways in which these materials can be used as detectors. Just as Ge transistors have much lower maximum operating temperatures than Si devices, so do Ge detectors. As a practical matter both Ge and Si photon detectors must be cooled in order to reduce the thermal charge carrier generation (noise) to an acceptable level. This requirement is quite aside from the lithium precipitation problem which made the old Ge(Li), and to some degree Si(Li) detectors, perishable at room temperature. 

Today, the food customer has a wide selection, almost year round. In order to secure maximum nutritive qualities, it is important that perishable foods be as fresh as possible. The produce manager can usually tell from whence most of his fresh foods come and from this, he can judge how much time has elapsed between picking and marketing. 

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