1,721,116 research outputs found
Strumenti di supporto alle decisioni per la tecnologia e l'ambiente: analisi multicriteriale deterministica applicata al progetto dei veicoli elettrici
No full text
Analisi di affidabilità in presenza di covariate aleatorie. Metodi probabilistici applicati alla manutenzione di dispositivi elettrici
No full textTesi di Dottorato. Depositata ai sensi di legge presso le Biblioteche Nazionali di Roma e Firenze
Bayes Availability Estimation of the “k-out-of-n” Partially Redundant System by Lognormal Prior Distributions
No full textThe “k-out-of-n” partially redundant reliability
architecture is a flexible and economic configuration for many
engineering systems, such as motor drive applications, in
various industrial, aerospace and naval systems. The present
study is aimed to develop a Bayesian statistical inference
approach for the steady state availability estimation of such
systems. The proposed approach is based upon Lognormal prior
distributions for both hazard and repair rates. The Lognormal
model appears indeed not only very flexible, but also
particularly tailored for electronic devices, as motivated in the
paper. A set of numerical applications with typical parameter
values is illustrated in the study, showing - by means of a large
sets of Monte Carlo simulations - that the proposed Bayesian
statistical inference approach is very efficient, accurate and
robust for the above availability estimation, particularly in the
case of data scarcity, which is a key feature of such high
reliability devices in view of parameter estimation. Beyond point
estimation, the study also develops an efficient method to obtain
the interval estimation of system availability by means of a
suitable Beta distribution approximation. Also a robustness
analysis of the above Lognormal model has been successfully
developed
Analisi di affidabilità in presenza di covariate aleatorie. Metodi probabilistici applicati alla manutenzione di dispositivi elettrici
No full textTesi di Dottorato. Depositata ai sensi di legge presso le Biblioteche Nazionali di Roma e Firenze
International Conference on Electrical Systems for Aircraft, Railway and Ship Propulsion (ESARS 2012)
No full textThe Burr XII Model and its Bayes Estimation for Wind Power Production Assessment
No full textThe probabilistic Burr XII model for the characterization and estimation of the wind-speed distribution is analyzed in the paper, in view of wind power production evaluation. Most of the existing methods for such evaluation are based upon the popular Weibull distribution for wind speed statistics. However, recent studies have pointed out some inadequacies in the Weibull distribution. The analysis of many field data show indeed significant “heavy tails” in the probability distribution of wind speed for large values of speed. This constitutes a critical aspect when the Weibull model is adopted, not only for its consequences on wind speed estimation, but especially on wind power estimation. The Burr model is here justified on theoretical grounds, being based on a proper "mixture" of Weibull probability distributions. After illustrating such derivation, a suitable Bayes approach for the estimation of the Burr model is proposed. The method is based upon the Negative Log-Gamma distribution for the assessment of prior information in a novel way which should be easily feasible for the system engineer. The method appears indeed to be very practical, since it only requires some prior information on the probability distribution of the wind speed. The results of a large set of numerical simulation are reported to illustrate the simplicity and efficiency of the proposed method
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