Approaches for Different Process Types

The number of parameters in the fuzzy sub-models is quite large. One rule of the fuzzy model for the net growth rate, for example, contains about 10 parameters, depending on the type of membership function that is used. Owing to the curse of dimensionahty the number of parameters increases exponentially for systems with higher dimensions. Therefore, only the consequence parameters have been optimized. 

Although it is possible to optimize the fuzzy models for // and r sequentially, it is interesting to see how the large-scale algorithm deals with optimization of a large set of parameters in a hybrid model. Therefore, all the parameters of the two fuzzy models will be optimized simultaneously. The result is that a set of 66 parameters will be optimized 48 premise part parameters and 18 consequence part parameters. The premise part parameters are constrained the bounds are set at the initial values 10%. No constraints were placed on the consequence part parameters. The results of the optimization are shown in Fig. 30.11. (for clarity, only some of the measurements are shown). The anomalous behavior has been removed and model offset has been reduced to acceptable levels. 

The next step is to analyze the hybrid model to determine whether the quality requirements are met. The hybrid model will be analyzed with respect to static performance, dynamic performance, complexity, interpretability and process independence. The complexity of the fuzzy models is mainly determined by the number of rales and the rale base. The clustering algorithm in combination with structure optimization provides a way to minimize fuzzy model complexity, which yielded acceptable results. 

For the polymer reactor the required irqruts of the fuzzy sub-models are obtained through a sensitivity analysis. The effect of lumping and data reduction on the accuracy of the model will be examined. 

For the digester the different sections of the process are assiuned to be lumped. It appeared that the simulation results improved owing to optimization of the entire integrated model. The extrapolation capabilities of the model are also tested. 

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In the early 1920s, a need was felt to have a unified approach for different disciphnes of chemical engineering, and thus, the concept of unit operations (Walker et al. 1923) was inuoduced. Subsequently, the concept of unit processes (Groggins 1958), which allowed ueatment of individual reaction types on a unified basis, was... 

Figure 30-lC is distinctly different from the first two in the type of SO2 control processes used and the sequence of the particulate matter and SOj controls. It is a promising approach for up to 90% SO2 control of western United States coal, and there is a single waste product. Other features include the collection of particulate matter at temperatures below 90°C and the possibility for spray dryer cooling tower water integration. This. system may or may not include a catalytic NO unit. 

In general, the optimum conditions cannot be precisely attained in real reactors. Therefore, the selection of the reactor type is made to approximate the optimum conditions as closely as possible. For this purpose, mathematical models of the process in several different types of reactors are derived. The optimum condition for selected parameters (e.g., temperature profile) is then compared with those obtained from the mathematical expressions for different reactors. Consequently, selection is based on the reactor type that most closely approaches the optimum. 

A database of the hazards associated with different types of equipment and unit operations including the applicability of inherently safer technology in each. As innovative solutions to hazards in equipment and process operations are discovered these could be included in this database for use by others in reducing risk in similar equipment and processes. A summary of design approaches for a number of common types of chemical process equipment will be published in CCPS (1997). This summary may be a starting point for the development of this database. 

An influential classification of the different types of information processing involved in industrial tasks was developed by J. Rasmussen of the Rise Laboratory in Denmark. This scheme provides a useful framework for identifying the types of error likely to occur in different operational situations, or within different aspects of the same task where different types of information processing demands on the individual may occur. The classification system, known as the skill-, rule-, knowledge-based (SRK) approach is described in a... 

An alternative approach for injection molding is the use of a rotary table injection machine. This type of machine uses the multistation concept, each station having a single cavity mold generally using a point gating/ injection point as previously mentioned. Consider a rotary table machine with eight stations, station one would be the injection station and station seven would be the unload and load metal insert station. This type of process has been successfully used for different types of lip type rotary shaft seals where more expensive elastomers are used and waste needs to be kept to a minimum. 

Sampling studies can be classified Into two types - enumeratlve, or descriptive, and analytic (j ). The classification Is Important because the applicable statistical methods and approaches are different for these two types. The objective of either type of study Is to provide a basis for action. In an enumeratlve study the action Is directed to the population from which the samples were taken. How or why the population was formed Is not of primary Interest. In an analytic study, the primary Interest Is the causal system or process which created the conditions observed In the study. Action taken Is directed toward this process rather than the population sampled. 

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