Process trends generalization

Fig. 17. Generalization of process trends for three distinct records (a) raw data (b)-(gl scaled signals (h) stable trends.

Fig, 23. (a) The raw data of three distinct records and (b) their corresponding syntactic generalizations. (Reprinted from Bakshi and Stephanopoulos, Representation of Process Trends, Part IV, Computers and Chemical Engineering, 18(4), p. 303, Copyright (1994), with kind permission from Elsevier Science Ltd., The Boulevard, Langford Lane, Kidlington 0X5 1GB. UK). 

Table II. General process trends for W CMP for ViPRR type wafer carrier. Up arrows mean that the parameter increases as a function of an increase in the process variable.

Tc, is increased the temperature of peak L is found to increase in direct proportion while that of peak H increases only slightly. As Tc is further increased, the L endotherm Increases in size while the H endotherm diminishes and eventually disappears. These trends generally confirm those reported previously (2 ). and suggest that the multiple peaks are most likely the result of lamellar thickening processes, perhaps requiring melting and recrystallization (23). 

The data set of metal corrosion provides a valuable insight as to which parameters dominate the corrosion process. The general meteorological features are well established in North America (although micrometeorological factors may dominate at any single exposure site). The pollutant related questions may be simply stated (1) what are the magnitudes of marine and industrial corrosion rates compared to the rural values (2) what are the relative rates in the rural eastern United States compared to the western rural values (3) what are the broad trends in corrosion rate over the years ... 

The number of KPIs in use should be small but they should provide a credible measurement as to trends. Generally they wiU be normalized. For example, rather than simply reporting the number of process safety incidents (PSls), it is more useful to report the number of incidents per employee. Doing so facilitates comparisons between different sites and organizations. 

The technological evolution occurring over the last 60 years of industrial history has also had an impact on chemical processes in general, and on the adipic acid production process in particular. This analysis offers us an opportunity to retrace over time the many difficult issues encountered in the development of a complex chemical process, such as the one at hand, and allows us to appreciate the importance of the history of the contributions made and the motivations underl5dng the changes introduced. Learning about this history will help us to avoid repeating the same mistakes and to move forward on a trend of constant improvement. 

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