The concept of the SPT diagram for ceramics is introduced as an essential aid to the design engineer when using engineering ceramics. For given conditions of stress state and distribution, environment, temperature and component size, the diagram enables estimates of a safe working stress to be made for specific component lifetimes and survival probabilities. The theory underlying the SPT diagram is reviewed. This involves the merging of the concepts of statistical variations in strength, with sub-critical crack growth which leads to delayed fracture. It is shown how the SPT diagram can be generated by simple measurements of the strain rate dependence of fracture strength. Data for the delayed fracture of alumina are used to demonstrate the reliability of SPT diagram.

A large number of model probability density functions (PDFs) are used to analyze atmospheric scintillation statistics. We have analyzed scintillation data from two different experimental setups covering a range of scintillation strengths to determine which candidate model PDFs best describe the experimental data. The PDFs were fitted to the experimental data using the method of least squares. The root-mean-squared fitting error was used to monitor the goodness of fit. The results of the fitting were found to depend strongly on the scintillation strength. We find that the log normally modulated Rician and the log normal PDFs are the best fit to the experimental data over the range of scintillation strengths encountered.

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