Situation-action rules

SCOPE and LIMITATIONS comprise the main body of the transform. They are situation-action rules which explore the context of the reaction site and alter the PRIORITY or other values to reflect the influence certain structural features have on the plausibility of this reaction. PRIORITY is one of eight vaiables 

ACS Symposium Series American Chemical Society Washington, DC, 1977. 

The ALCHEM transforms are gathered together in unordered sequential source files. These source files are compiled by SYNCOM into efficient binary direct access CHM files complete 

A transform is not viewed as a program, but rather as a statement of facts. It does not contain GO TO s, LOOPS, SUBROUTINE calls, and does not reference any other transform. Each transform is independent of any other transform. Further a transform contains no strategies or heuristics about when its 

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If the nature of the problem is not readily apparent, then it might be necessary to go to the rule-based level. In this case a diagnostic rule will be applied to identify the state of the plant and an action rule used to select an appropriate response. Control will revert to the skill-based level to actually execute the required actions. More abstract functions such as situation evaluation and planning will only be required at the knowledge-based level if the problem cannot not be resolved at the rule-based level. 

If the pattern does not fit into an immediately identifiable pattern, the process worker may then consciously apply more explicit "if-then" rules to link the various symptoms with likely causes. Three alternative outcomes are possible from this process. If the diagnosis and the required actions are very closely linked (because this situation arises frequently) then a branch to the Execute Actions box will occur. If the required action is less obvious, then the branch to the Select/Formulate Actions box will be likely, where specific action rules of the form "if situation is X then do Y" will be applied. A third possibility is that the operating team are unable or imwilling to respond immediately to the situation because they are uncertain about its implications for safety and/or production. They will then move to the Implications of plant state box. 

The output of stage 2 must finally be integrated into the existing theory. At the outset, this will, of course, be zero. But as soon as two structural essences and two process sets exist, it must be determined whether the second is just a corollary of the first, or vice versa, or whether they are disjoint situations with their associated actions. The theory will then take the form of these so-called situation-action rules The situations are the structural essences and the actions are the process sets. 

Because the activation of knowledge-based actions depends on the information perceived by the operator, information filtering, distortion, or biases may impact when action rules are activated. This could lead to hmnan error events such as the execution of a knowledge-based rule during an inappropriate situation (Reason, 1990). 

Figure 9.3 (b) bottom half). Simulation would be conducted in various situations so that condition action rules are determined (Figure 9.3 (c)). The last module of (c), the controller with condition action rules is necessary for real-time... 

Rule-based errors are a consequence of if this, then that action rules. Errors of this type may occur when there is insufficient training or currency with the operating environment. The mle may be inappropriately applied to the given situation. 

Policies enable managers to control events in advance. Before the action begins, people know the rules and so are more likely to produce the right results first time. Without policies, one is forced to control events in arrears, after something has happened to cause dissatisfaction. Alternatively, one has to be on the scene of the event to respond as soon as the situation approaches the limits. This is a costly use of managers time. 

This aspect of the model is illustrated in Figure 1.5. The error tendencies circle represents the intrinsic characteristics of people that predispose them to error. These tendencies include a finite capability to process information, a reliance on rules (which may not be appropriate) to handle commonly occurring situations, and variability in performing unfamiliar actions. These error tendencies are discussed in detail in Chapter 2. 

With regard to mistakes, two separate mechanisms operate. In the rule-based mode, an error of intention can arise if an incorrect diagnostic rule is used. For example, a worker who has considerable experience in operating a batch reactor may have learned diagnostic rules that are inappropriate for continuous process operations. If he or she attempts to apply these rules to evaluate the cause of a continuous process disturbance, a misdiagnosis could result, which could then lead to an inappropriate action. In other situations, there is a tendency to overuse diagnostic rules that have been successful in the past. 

As an example of suspected endocrine disruptors (EDs), studies of the estrogenic action of bisphenol A (BPA) have been in progress in medical, physiological, and biological fields. In this situation, physicochemical approaches are required to get the structural information of BPA trapped in biomembranes. Most recently, we have determined the site and the orientation of BPA trapped in phospholipid vesicles by NMR, using the HCS rule [47]. In particular, we have succeeded in monitoring the NMR spectral changes of phospholipid vesicles, which are induced by the BPA delivery. 

A more difficult situation arises when we need to model a system in which the users may decide, while the system is running, that they need essentially new classes of items, with new attributes, business rules, and actions. 

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