Graph model building

Ferenczy, G. G. and Morris, G. M. (1989) The active site of cytochrome P-450 nifedipine oxidase a model-building study. J. Mol. Graph. 7, 206-11. 

It is generally hard to let graphs like the ones in Figure 7.13 guide the covariate model building process. The problem lies in the fact that covariates tend to be correlated. This is to some extent illustrated in Figure 7.13. The parameter values... 

Figure 7.14 is based on a model in which creatinine clearance was included. The axis limits are the same as in Figure 7.13 and it is clear that the unexplained variability has decreased. At the same time it appears as if the sex relation is not as important anymore. On the other hand, had sex been included in the model instead of creatinine clearance then the picture would perhaps have looked the same. Again, this is the problem with using graphs to guide covariate model building. Clearly some other techniques are necessary (see other chapters in this book). 

Measurements from the real system are overloaded with noise. In order to be able to clearly identify the set of ARRs with residuals close to zero, measured data should undergo appropriate filtering before it is used in the evaluation of ARRs. Moreover, some of the sensors providing measured values may operate in a faulty mode due to external disturbances caused by changes in the ambient or by internal parametric faults. If details of the internal build-up of a sensor are not fully known so that abond graph model cannot be developed, then for small changes, its dynamic behaviour may be approximately captured by a transfer function that, at least, accounts for the sensor s delay and its gain. 

Huggins Molecular Models.—In a series of, so far, 14 papers, Huggins has developed an approach to solution thermodynamics that essentially builds on lattice-graph models, removing phenomenological parameters by re-expressing them in terms of molecular quantities obtained, as far as is possible, by independent experimental means. Thus far the theory has been applied mainly to non-polymer systems. The most recent part considers benzene solutions of n-alkanes as model oligomers for polyethylene. 

The bond graph method defines the structure and constitutive equations of the system. Standard bond graph elements are used to build a model of the structure of the system. Suitable computer programs are available to generate the governing equations, and alternative methods have also been developed for deriving equivalent block diagrams, which can represent nonlinear systems. 

The topic of the present section is a formulation of an alternative graph-theoretical model of synthons [16,24]. Such an approach makes it possible to build-up all concepts and notions of synthon theory [18-22] in a very transparent and easily understandable level. 

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