Production Network Optimization Phase

As each alternative network configuration already possesses an optimum objective function value based on the scenarios/restrictions underlying the calculation, evaluation of the alternatives has to focus on aspects other than financial optimization. 

One aspect becoming increasingly important is the robustness of the network configuration (cf. Goetschalckx and Fleischmann 2005, p. 118). One way of establishing a robust solution is to perform sensitivity or scenario analyses on major influencing factors such as demand expectations 

Once the alternatives have been evaluated, management has to chose the preferred network design and approve an implementation project. Alternatively, the planning process has to be repeated to develop further alternatives. 

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In the following chapters the individual phases of the planning process and the major activities taking place in each phase are outlined. The decision support tools proposed for the production network optimization phase and the site selection phase will be developed in Chapters 3 and 4 respectively. 

The need to evaluate production sites can arise in different situations. Most obviously, a network optimization project resulting in the decision to establish new production capacity may require a site selection phase in one or more countries (cf. Chap. 2.4.4). Depending on the status quo, the task either is to identify and evaluate potential production sites or to choose the most suitable one from a set of existing sites. Conversely, if capacity is to be reduced potential closure candidates might have to be assessed to identify the one least suitable for future use. Additionally, as pointed out in Chapter 2.4.5, a regular evaluation of all production sites is also required in the context of site controlling. Here the objective is to rank a company s entire portfolio of existing sites to identify action needs. 

Emulsion stability is required in many dairy applications, but not all. In products like whipped cream and ice cream, the emulsion must be stable in the liquid form but must partially coalesce readily upon foaming and the application of shear. The structure and physical properties of whipped cream and ice cream depend on the establishment of a fat-globule network. In cream whipped to maximum stability, partially coalesced fat covers the air interface. In ice cream, partially coalesced fat exists both in the serum phase and at the air interface also, there is more globular fat at the air interface with increasing fat destabilization. Partial coalescence occurs due to the collisions in a shear field of partially crystalline fat-emulsion droplets with sufficiently-weak steric stabilization (low level of surface adsoiption of amphiphilic material to the interface per unit area). To achieve optimal fat crystallinity, the process is very dependent on the composition of the triglycerides and the temperature. It is also possible to manipulate the adsorbed layer to reduce steric stabilization to an optimal level for emulsion stability and rapid partial coalescence upon the application of shear. This can be done either by addition of a small-molecule surfactant to a protein-stabilized emulsion or by a reduction of protein adsorption to a minimal level through selective homogenization. 

DMH is an intermediate in peroxide chemistry and could be used for synthesis in the field of lubricant or polyester. So far research has mainly focused on the development of different catalysts and the comparison of their performance [1]. Despite intensive optimization of catalysts and reaction conditions, selectivity to DMH is still low, because molecular oxygen in the gas-phase causes deep oxidation. Beside the development of catalysts and the optimization of reaction conditions, the mode of gas-solid contact and the reactor configurations are important issues as well. As in any parallel-series network with valuable intermediate products, the design of the reactor has a strong influence on the selectivity towards DMH. In principle, modes of contact which maintain a low oxygen concentration in the reactor favour the desired reaction and thus improve selectivity. Obviously, the requirement of a low oxygen concentration in the gas phase can be met by using a redox-type operation in which a... 

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