Efstratios Nikolaidis

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This paper compares probabilistic and possibility-based methods for design under uncertainty. It studies the effect of the amount of data about uncertainty on the effectiveness of each method. Only systems whose failure is catastrophic are considered, where catastrophic means that the boundary between success and failure is sharp. First, the paper examines(More)
This paper compares Evidence Theory (ET) and Bayesian Theory (BT) for uncertainty modeling and decision under uncertainty, when the evidence about uncertainty is imprecise. The basic concepts of ET and BT are introduced and the ways these theories model uncertainties, propagate them through systems and assess the safety of these systems are presented. ET(More)
The objective of this paper is to compare probabilistic models and fuzzy set models for design against uncertainty when there is limited information about the statistics of the uncertainty or modeling error. First, we compare the axioms of probabilistic and fuzzy set methods and the rules governing the arithmetic operations that these methods use. Then, we(More)
Thin walled stiffened composite panels, which are among the most utilized structural elements in engineering, possess the unfortunate property of being highly sensitive to geometrical imperfections. Existing analysis codes can predict the buckling load of a structure with specified initial imperfections. However, it is impossible to determine the amplitude(More)
Methods for designing targeted tests for reliability validation of structures obtained from reliability-based design are presented. These methods optimize the test parameters to minimize the variance in the estimated reliability (or equivalently the failure probability) estimated from the tests. The tests are designed using information from analytical(More)
In reliability design, often, there is scarce data for constructing probabilistic models. It is particularly challenging to model uncertainty in variables when the type of their probability distributions is unknown. Moreover, it is expensive to estimate the upper and lower bounds of the reliability of a system involving such variables. A method for modeling(More)
An approximate, closed-form expression for the value of the integral encountered inthe calculation ofthe probability density function (PDF) of the envelope of a partially saturated ocean acoustic process i obtained. Furthermore, an expression of this PDF as a series of modified Bessel functions i presented. The results may also be directly applied to the(More)
The aim of this study was to determine the effect(s) of dietary omega-3 polyunsaturated fatty acids (ω-3 PUFA) on rabbit semen. Adult rabbit bucks were assigned to two groups that were given two diets, a standard diet (control) and a diet supplemented with ω-3 PUFA. Sperm samples were collected from all bucks with the use of an artificial vagina in 20-day(More)
We present in this paper a library to compute with Taylor models, a technique extending interval arithmetic to reduce decorrelation and to solve differential equations. Numerical software usually produces only numerical results. Our library can be used to produce both results and proofs. As seen during the development of Fermat’s last theorem reported by(More)