Polymer grade transition control using advanced real-time optimization software

This paper describes the application of an industrial real-time optimization package (ROMeo¹) to the nonlinear model predictive control (NLMPC) of a simulated polymer grade transition. The NLMPC algorithm is formulated using orthogonal collocation to integrate the model equations, and sequential quadratic programming to solve the resulting nonlinear programming problem. A receding horizon estimation scheme and, separately, a Luenberger observer are designed to reconstruct unmeasured states. The resulting algorithm is demonstrated on two simulated polymerization case studies: (i) continuous methyl methacrylate and (ii) gas-phase polyethylene.     

Electrocerebral recovery during the intracarotid amobarbital procedure: influence of interval between injections

PURPOSE AND METHODS: During the intracarotid amobarbital procedure (IAP) at the University of Michigan, continuous scalp EEG monitoring guides the timing for presentation of memory items and postinjection testing. Most of our patients have undergone bilateral injections. The interval between injections varied from 22 to 60 min, depending on the test and recovery time, as well as the time to catheterize the second side. After noting a trend toward prolonged electrographic recovery following the second injection, we tested our clinical impression that recovery of the second hemisphere may be influenced by (a) the time between injections and (b) which hemisphere is injected first (epileptogenic or nonepileptogenic). To study these questions, we analyzed EEG recovery data from 48 consecutive IAPs. Approximately half the patients had the epileptogenic side injected first. RESULTS: We found that (a) electrographic recovery after the second injection is prolonged if the interval between bilateral injections is less than 40 minutes and (b) electrographic recovery is more rapid after injection of the epileptogenic hemisphere. CONCLUSIONS: We now recommend waiting at least 45 min between injections. The pathophysiology of more prolonged amobarbital effect on the nonepileptogenic hemisphere than on the epileptogenic hemisphere remains unclear.     

DSS approach for heterogeneous parallel machines scheduling considering proximate supply chain constraints

This paper describes the basis of a Decision Support System (DSS) designed to schedule fertiliser production orders to be delivered within time windows, in plants made up of multiple heterogeneous parallel processors (production lines), considering that fertiliser production rates and nomenclatures depend on lines, that setup times depend on sequence and lines, and taking into account downtime constraints (preventive maintenance?…). A mixed linear programming model is encapsulated in the DSS which considers the schedule’s impacts, immediately upstream and downstream of plants in the supply chain. These side-effects may make the proposed solution unfeasible and the DSS helps redefining the problem to avoid them.