Performance assessment basic suitability

Those performance standards associated with establishing initial suitability may be different from those used to assess ongoing suitability throughout the operational life of the safety-critical element. Some companies prefer to merge both requirements in to one (i.e., initial and ongoing suitability), or some prefer to develop separate performance standards. Regardless of the approach, the basic objective is to ensure that the requirements set in the performance standards assure that the safety-critical element can fulfill its function. 

Many methods have been developed that are suitable for assessing risks associated with the operation of facilities involving chemical reactivity hazards. The more commonly used methods are summarized in Table 4.9. They differ in their applicability, level of effort, and how systematic they are in identifying accident scenarios. All of the methods except layer of protection analysis (LOPA) may be applied qualitatively, and all except checklist reviews may be performed in at least a semiquantitative manner. CCPS (1992a) is a basic source of information on each of these methods. 

An alternative approach is to assess a service application in terms of the relative importance of basic wear mechanisms (abrasion, fatigue, adhesion, impact/slide, erosion etc) and the geometry and motion. Small scale tests are then carried out in the laboratory to simulate these mechanisms and parameters in order to produce relevant wear data. The performance data for each material with reference to each of these tests will therefore grade the suitability of that material to the proposed application. 

The most suitable method for the quantitative evaluation of the positive inotropic effect of a cardioactive steroid is at present the assessment of its influence on the isometric contraction curve, measiured in isolated papillary muscles. However, to obtain reliable data for the comparison of the inotropic potency of the various cardioactive steroids, it is important to perform the experiments under identical conditions [16]. Because of the variety of test conditions used, it is not easy or it is even impossible to compare the data reported in the literature [17,18]. A comprehensive survey of the structure-activity relationships found in guinea-pig left atria under identical conditions has recently been presented by R. Thomas and coworkers [19]. Therefore, this aspect will be mentioned here only with regard to the two basic risks for misinterpretation of pharmacological data from animal model systems. 

The basic estimation work has been performed by Gauss in early 1800s who tried to fit the most suitable curve through the scatter of points by having the least squares technique as a criterion which constitutes without exception the basis of any uncertainty event assessment in statistics and stochastic processes modeling. The successful application of the least squares technique for almost two centuries is due to the following factors. 

To overcome present problems associated with the life prediction of seals, a collaborative research project was initiated at British Hydraulics Research Group. The scope of the research included the determination of basic parameters using test specimens development of a computer program to apply these results to actual seals and performance tests on 500 seals under controlled conditions. In addition, a Seal Life Prediction Methodology is being compiled for a predictive tool for use in the assessment of the suitability of elastomers for particular applications. Details are given. 

Prediction of earthquake-induced collapse requires the identification of all possible modes of collapse, appropriate structural modeling of building components under cyclic loading, and suitable representation of earthquake excitation including the consideraticm of epistemic and aleatory uncertainties. Krawinkler et al. (2009), Haselton et al. (2009), and Baradaran Shoraka (2013) provide insights into the phenomenon of dynamic collapse of earthquake-excited structures. For basic concepts in prediction of collapse and its implementation to performance-based earthquake engineering, the reader is referred to Zareian et al. (2010). VUlaverde (2007) presents a comprehensive literature that provides a path through which seismic collapse assessment has evolved in the last decades. 

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