Trade-off index

Figure 11.12 Reactor performance-pressure drop trade-off index (Eq. (11.35)) for different structured reactors. Gas phase, physical properties air (STP, standard temperature and pressure).

As demonstrated in Figure 11.12, the trade-off index of microstructured channels is roughly five times higher compared to that of packed beds. This means that the energy dissipation for the same mass transfer performance in a packed bed is five times higher than in a microchannel. 

The performance of the foam can be evaluated based on the trade-off index defined in Eq. (11.35). In Figure 11.12, the index of foams is compared to microchannels and packed beds. Depending on the Re number, the performance approaches the performance predicted for microchannels and monoliths. Therefore, open cell foams must be considered as valuable catalyst supports for efficient PL... 

This leads to the following relation, which can be interpreted as a mass transfer effectiveness or trade-off index [56]. 

Effectiveness factor (mass transfer) or trade-off index... 

Figure 9.13. Example 2D substructure search queries with various atom and bond query features. The more features that are present, the more flexible the search becomes, but the search may also require more time to complete. There is a trade-off between putting the flexibility into the database (i.e., storing and indexing multiple forms of a structure) and putting the flexibility into the search query and the search software.

This index could be used for trading off risk and cost but such indices oversimplify a complex tradeoff. The mapping between F and risk is not direct. Some parameters may never violate their bounds, others may have a significant probability of doing so. The use of F treats all parameters as having a uniform likelihood of violating their bounds, which is not generally appropriate. 

The binormalized quadratic index was proposed, together with the binormalized centric index C, to provide information on the topological shape of trees, i.e. the trade-off between linear and star graphs. 

From the above lists, there is a natural trade-off between viscosity index and pour point, e.g. by increasing the linearity of the ester, the viscosity index improves but the pour point increases. Esters made from mixtures of normal and branched acids with the same carbon number have viscosity indices between those of the normal and branched acid esters. But their pour points are lower than those esters formed separately from either branched or normal acids. 

In Exhibits 8.14 and 8.15, we use the same data to construct two efficient frontiers of portfolios—one without index-linked gilts as an available asset choice and one where index-linked can be selected. For the first frontier below, without linkers, gold is still selected for the lowest risk portfolios because of its diversifying characteristics, in spite of its dreadful risk-return trade-off over the 21 years. Flowever, it quickly disappears from optimal portfolios along the frontier if risk tolerance is raised a tiny bit. The asset mixes of a selection of portfolios along the frontier are also detailed. 

Note that there is a multiparameter trade-off between grating-based (interferometric) evaluation of displacement and direct interferometric evaluation. Typical grating-based systems have relatively short non-common paths, resulting in reduced sensitivity to time-varying index effects. There is, however, increased sensitivity to cyclic effects in grating production and Imig-range effects of coefficient of thermal expansion. A detailed discussion of this trade-off is beyond the scope of this article. 

In laboratory studies of human behaviour error is commonly used as an index of performance. A common finding in these studies is the marked trade-off between the speed of response and number of errors made. An example of this trade-off is shown in Figure 23.3. It is interesting to note that many of these approaches have been incorporated into concepts of human error as they apply to considerations of safety. 

Only when the performance index can be expressed in the same units as cost, one can construct a true cost minimization algorithm. Before that is obtained, one needs to look at a spectrum of solutions and decide the best trade-off of performance vs. cost. In any case, the Pareto optimum space over the different objectives can be determined. 

As far as the impact assessment with the two different methods CML and SPI are concerned the results show concordant trends. The CML method addresses with its impact categories the various environmental problems in detail and is capable of highlighting the trade-offs between them. In contrast to this the Sustainable Process Index is aggregated across different impact categories and allows comparison of these effects based on natural flows and natural qualities. 

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