Processing times, activation index

At the end of the simulation of the full model, the time response of the output variables in (2.3) is available for the activity analysis. Given these output variables, the element power is calculated. Then, the activity metric is calculated using (2.2). Finally, the activity index in (2.5) of each element is calculated. The activity indices are then sorted in descending order to identify the elements with high activity, considered more important, and low activity, considered less important. The result of the sorting process is the ranking of the element importance and it is represented with the vector r as shown in (2.17). The first element of this vector points to... 

As shown in Table 5.1, different modification times have different effects on whiskers. The activation index of calcium carbonate whiskers approach a maximum of 93.4% when the processing time is 50 minutes. With an increase of processing time, more modifier molecules are adsorbed on the surface of the whiskers, and the effect of the modification increases gradually. When the processing time is up to 50 minutes, the modification agent can make sufficient contact with the whiskers and fully coat their surface to the maximum activation index. When the modification time extends further, the already adsorbed modification agent on the material surface desorbs, and the modification effect deteriorates. 

Table 5.1 Relationship between Different Processing Times and the Activation Index...

A number of indices relate metal activity to hydrogen and coke production. (These indices predate the use of metal passivation in the FCC process but are still reliable). The most commonly used index is 4 X Nickel + Vanadium. This indicates that nickel is four times as actiw as vanadium in producing hydrogen. Other indices [9] used are ... 

The time to reach a certain PV may be used as an index of oxidative stability for food lipids. The effects of antioxidants and food processing on fats are often monitored in this way. Thus, a longer time period to reach a certain PV is generally indicative of a better antioxidant activity for the additive under examination. However, a low PV represents either early or advanced oxidation the breakdown of peroxides to secondary oxidation products will result in a decrease in PVs during the storage period. For determination in foodstuff, a major disadvantage to the classical iodometric PV assay is that a 5-g test portion is required it is sometimes difficult to obtain sufficient quantities of lipid from foods low in fat. Despite its drawbacks, PV determination is one of the most common tests employed to monitor lipid oxidation. 

This effect is related with the Stimulated Raman scattering process. A strong beam (pump) incident on a Raman active medium induces a change of the refractive index, which in turn influences the propagation of a weaker beam (probe). A typical value for Raman susceptibility is Re(x 5 ) 10 esu, with a time response 10 s. 

FIGURE 127 In R R activation, longer hold times result in polymer of higher melt index because the dehydroxylation step in CO is a time-dependent process. 

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