Non Linear And Dynamic System Analysis

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Even though it is not a fundamental limitation of functional units based on a unit amount of service, it can be observed that they typically lead to static and linear models which lack the capacity to investigate the non-linear or dynamic properties that are present in the reverse supply chains they model and evaluate (McLaren et al. 2000). There are at least two different approaches that are more conducive to non-linear and dynamic system analysis. The first uses a functional unit based on total amount of service instead of unit amount of service. The resulting reference flow denotes the total amount of products Q required to deliver the service. This approach is commonplace in the microeconomic theory of supply (Begg et al. 2003, Varian,…show more content…
The introduction of time as a system variable also makes it necessary to define temporal system boundaries. In this study, the functional unit has been chosen under assumption that study will be used internally only, in which case the engineers and operators are concerned with assessing and improving the reverse supply chain performance on the basis of its actual operation. Therefore, interest here lies in analysing the effect of marginal changes around an existing state of the supply chain. Hence, the functional unit has been defined as “operation of the reverse supply chain for a certain period of time. 3.2.3 System Boundary As in other life cycle studies, it is useful to use the concepts of “foreground” and “background” systems (e.g. Clift et al., 1999, 2000). This helps to distinguish between reverse supply chain of direct interest in the study, and other operations with which they exchange materials and energy. The forground systems may be defined as the endogenous part of the supply chain, which includes the set of processes whose selection or model of operation is affected directly by the decision of study. The background denotes the exogeneous parts of the supply chain, compromising all other processes that interact directly with the foreground system, usually by supplying material or energy to the foreground or receiving material and energy from it. This concept is illustrated in Figure 3.2. Figure 3.2
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