Common cost model

To put every scenario on a common basis, CGR Management Consultants and SFI developed a common cost model. Its purpose was to eliminate these differences when evaluating the underlying changes in location. The model, called SITELINK, used a structure that is adaptable for supply chain network optimization modeling. Figure 44.1 is a simplified stmcture of the SITELINK model. 

In Section IV we considered a categorical performance metric y. Although that represents a common practice, especially when y defines the quality of a product or process operation, there are many instances where system performance is measured by a continuous variable. Even when y is quality-related, it is becoming increasingly clear that explicit continuous quality cost models should be adopted and replace evaluations of performance based on categorical variables. 

Density functional theory (DFT) is based on the Hohenberg-Kohn theorem, which states that there is a functional which gives the exact ground-state energy for the exact electron density. DFT models have become very popular because they are not more costly than Hartree-Fock models. The reason is that in the HF, Cl and MP models, a wavefunction for an N-electron system depends on 3N coordinates, whereas in the DFT approach, the electron density depends on only three coordinates, irrespective of the number of electrons. The problem is that the exact functional would be the Schrodinger equation itself Several approximate functionals have been developed by many authors (Becke, Parr, Perdew, and others) and different forms of the functional can yield slightly different results. Some of the most common DFT models are ... 

The generic permselectivity of a membrane can be described by the retention coefficient for liquid phase or the separation factor for gas phase. Separation factor will be defined and discussed in Chapter 7. In the case of liquid-phase membrane separation, the retention coefficient of the membrane can be characterized by some commonly used model molecules such as polyethylene glycol (PEG) polymers which have linear chains and arc more flexible or dextians which arc slightly branched. The choice of these model molecules is due to their relatively low cost. They are quite deviated from the generally... 

Another extremely important factor is process economics. We are always interested in finding the most economical solution. Often it means the survival of the company. Process economics means the cost efficiency of the processes. For mass production, a very detailed economic analysis is necessary before a specific processing method can be selected. However, for the usual small to medium batch production, it is not practical to conduct a very detailed study. The savings cannot justify the amount of effort spent. Some rough estimation or just common sense should be used to select a better process. Whenever there are more than two candidate processes, both technologically suitable for the task, it is time to compare their relative costs. A process cost model can be stated as ... 

Analytical models Mathematical models in this category are ranging firom simple to very complex models, and they are considered as the most commonly used cost models. 

Table 1 presents the available LCC tools which are used in practice (Gluch and Baumann 2004). These tools are often classified into a generic and a specific cost model. The specific cost model is the modified generic model which is developed with the system boundary of LCC. A generic model is often developed as a summation of the common cost elements that are related to the product life cycle (Table 1). 

These issues can likely be represented in a mathematically straightforward way, but as always the challenge is tractability of analysis. We note that existing multi-channel models have inherited many of the cost-related simplifications that are common in models of a single channel or even a single firm. 

Structural theory facilitates the evaluation of exergy cost and incorporation of thermoeconomics functional analysis (Erlach et al., 1999). It is a common formulation for the various thermoeconomic methods providing the costing equations from a set of modeling equations for the components of a system. The structural theory needs a productive structure displaying how the resource... 

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