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Sensitivity analysis study of the source parameter uncertainty factors for predicting near-field strong ground motion

Li Z., Gao M., Jiang H., Chen X., Li T., Zhao X.

Acta Geophysica

2018

Vol. 66, no. 4

523--540

Uncertainty factors have substantial influences on the numerical simulations of earthquakes. However, most simulation methods are deterministic and do not sufficiently consider those uncertainty factors. A good approach for predicting future destructive earthquakes that is also applied to probabilistic hazard analysis is studying those uncertainty factors, which is very significant for improving the reliability and accuracy of ground-motion predictions. In this paper, we investigated several uncertainty factors, namely the initial rupture point, stress drop, and number of sub-faults, all of which display substantial influences on ground-motion predictions, via sensitivity analysis. The associated uncertainties are derived by considering the uncertainties in the parameter values, as those uncertainties are associated with the ground motion itself. A sensitivity analysis confirms which uncertainty factors have large influences on ground motion predictions, based upon which we can allocate appropriate weights to those uncertainty factors during the prediction process. We employ the empirical Green function method as a numerical simulation tool. The effectiveness of this method has been previously validated, especially in areas with sufficient earthquake record data such as Japan, Southwest China, and Taiwan, China. Accordingly, we analyse the sensitivities of the uncertainty factors during a prediction of strong ground motion using the empirical Green function method. We consequently draw the following conclusions. (1) The stress drop has the largest influence on ground-motion predictions. The discrepancy between the maximum and minimum PGA among three different stations is very large. In addition, the PGV and PGD also change drastically. The Arias intensity increases exponentially with an increase in the stress drop ratio of two earthquakes. (2) The number of sub-faults also has a large influence on various ground-motion parameters but a small influence on the Fourier spectrum and response spectrum. (3) The initial rupture point largely influences the PGA and Arias intensity. We will accordingly pay additional attention to these uncertainty factors when we conduct ground-motion predictions in the future.

Definiowanie czynników niepewności i nieprecyzyjności na potrzeby wspomagania diagnozy medycznej

Straszecka E., Straszecka J., Marcisz Cz.

Zeszyty Naukowe. Elektronika / Politechnika Śląska

2000

z. 12

31-48

W pracy zaproponowano modelowanie czynników niepewności i nieprecyzyjności reguły typu "jeżeli... to ..." w przypadku jej zastosowania do wspomagania diagnozy medycznej. Omówiono sposoby opisu nieprecyzyjnej przesłanki za pomocą zbioru rozmytego i skali. Zastosowano jednolitą interpretację nieprecyzyjnej przesłanki, niezależnie od sposobu jej określenia (zbiór rozmyty, skala, wartość O lub 1). Z pomocą teorii Dempstera-Shafera zdefiniowano pewność diagnozy (konkluzji). Podano przykład wnioskowania we wspomaganiu diagnostyki chorób tarczycy.

Uncertainty and imprecision factors modelling for IF-THEN rules used in medical diagnosis support is proposed in the paper. A method of interpretation of an imprecise predicate using fuzzy sets or a scale is described. A unified representation of the imprecise predicate, independently from the manner of its formulation (a fuzzy set, a scale, 0 or 1 values) is suggested. Certainty of a diagnosis (conclusion) is defined on Depster-Shafer theory. An example of reasoning in thyroid gland diagnosis support is provided.