Scheduling module

The constraints considered in the mathematical formulation are divided into two modules. The first deals with the mass balance constraints and the second with the sequencing and scheduling constraints. The mass balance constraints for the case where there is no central storage are slightly different to those for the case where there is. The mass balances for each are described in the mass balance module below. The sequencing and scheduling module will be described, for both cases, in a subsequent section. The nomenclature for all the sets, variables and parameters can be found in the nomenclature list. 

As with the multiple contaminant wastewater minimisation model, the mathematical model for multiple storage vessels comprises of two modules, namely, a mass balance module and a scheduling module. The constraints that comprise the mass balance module are described first. 

The constraints presented above complete the constraints necessary for the mass balances. Due to the discontinuous nature of the operation under consideration, constraints also have to be derived that capture the essence of time. These are presented in the scheduling module below. 

The constraints that comprise the scheduling module of the model are divided into four groups, namely, task scheduling, direct recycle/reuse scheduling, storage scheduling and time horizon constraints. 

The constraints given above complete the scheduling module of the model. The final part of the model that needs consideration is the objective function. 

The simulation of a production run of a pipeless plant is realized by a 2-level algorithm which incorporates a scheduling module, a routing module and a simulation module. 

On the upper level, the scheduling module allocates the equipment which is required for processing the next batch. In these decisions, the current equipment allocation, the equipment properties and a cost-function are taken into account. The allocation is performed in a sequence according to increasing starting times of the batches. 

The routing module and the discrete event process simulator are triggered by the scheduling module. 

The scheduling module maintains a master list of all batches and control-recipes and sorts the basic operations of the chronologically next control-recipe by their position in the recipe. In the case of identical starting times a priority which can be specified on the batch level determines the sorting. During the sorting procedure parallel steps in the recipe with all associated basic operations are regarded as one unit. 

The routing module which is called by the scheduling-module calculates the fastest conflict-free path of a transportation job between two positions of the plant. 

The simulation module simulates the basic operation(s) which are processed by a combination of a vessel and a station using a discrete event simulator. All necessary data (basic operation(s), equipment parameters, recipe scaling percentage, etc.) is provided by the scheduling-module. The simulator calculates the processing times and the state changes of the contents of the vessels (mass, temperature, concentrations, etc.) that are relevant for logistic considerations. 

The short-term planning process is dealt with in the Production Planning and Detailed Scheduling module within SAP APO. PP/DS considers a horizon of two to three months. In contrast to SNP planning, there is no cross-location planning in PP/DS. 

A sample scheduling module that automatically logs in the sample, prints bar-coded labels and assigns analyses for routine projects. 

The Schedule module is used by physician to schedule meetings with patients, interventions and other events. This module contains a reminder for upcoming and important events. 

Overview of transformations, allocation, scheduling, module generation, and layout synUiesis. 

In order to limit the damage that has already occurred (delayed deadlines and high capital tie-up) in conventional material requirements planning systems and ERP systems, an extremely complex EDP module, the so-called capacity scheduling module, is activated (Fig. 29). 

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