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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.

Location-scale bivariate Weibull distributions for bivariate lifetime modeling

Han, Yi, Carpenter, Mark. January 2005 (has links) (PDF)
Thesis (M.S.)--Auburn University, 2005. / Abstract. Vita. Includes bibliographic references (p.75-77).

Weibull diameter distribution models for managed stands of Douglas-fir in Washington and Oregon /

Eng, Helge. January 1985 (has links)
Thesis (M.S.)--Oregon State University, 1986. / Typescript (photocopy). Includes bibliographical references (leaves 28-31). Also available on the World Wide Web.

Statistics of Met-Ocean Conditions Between West and Central Gulf of Mexico Based on Field Measurements

Su, Lin 2012 May 1900 (has links)
Statistics of met-ocean conditions including wind, current and wave at the location between west and central Gulf of Mexico (GOM) are derived based on about three year of field measurements. Two-parameter Weibull distribution has been employed to fit wind speed at 10m over sea level and current speed in various depth. The joint probability contour was derived based on First-Order Reliability Method. In addition, the joint distribution of wind speed and direction was visualized by wind-rose diagram. The results provided in this study may provide essential information to the probability distribution of met-ocean condition in the particular location and can be used as a reference in the future designs.

Mixed Weibull distributions in reliability engineering: Statistical models for the lifetime of units with multiple modes of failure.

Jiang, Siyuan. January 1991 (has links)
The finite mixed Weibull distribution is an appropriate distribution in modeling the lifetime of the units having more than one possible failure cause. Due to the lack of a systematic statistical procedure of fitting the distribution to a data set, it has not been widely used in lifetime data analyses. Many areas on this subject have been studied in this research. The following are the findings and contributions. Through a change of variable, 5 parameters in a two Weibull mixture can be reduced to 3. A parameter'vector (p₁, η, β) defines a family of two-Weibull mixtures which have common characteristics. Numerous probability plots are investigated on Weibull probability paper (WPP). For a given p₁ the η-β plane is partitioned into seven regions which are labeled by A through F and S. The Region S represents the two Weibull mixtures whose cdf curves are very close to a straight line. The Regions A through F represent six typical shapes of the cdf curves on WPP, respectively. The two-Weibull mixtures in one region have similar characteristics. Three important features of the two-Weibull mixture with well separated subpopulations are proved. Two existing methods for the graphical estimation of the parameters are discussed, and one is recommended over the other. The EM algorithm is successfully applied to solve the MLE for mixed Weibull distributions when m, the number of subpopulations in a mixture is known. The algorithms for complete, censored, grouped and suspended samples with non-postmortem and postmortem failures are developed accordingly. The developed algorithms are powerful, efficient and they are insensitive to the initial guesses. Extensive Monte Carlo simulations are performed. The distributions of the MLE of the parameters and of the reliability of a two Weibull mixture are studied. The MLEs of the parameters are sensitive to the degree of separation of the two subpopulation pdfs, but the MLE of the reliability is not. The generalized likelihood ratio (GLR) test is used to determine m. Under H₀: m=1 and H₁: m=m₁>1, ζ, the GLR is independent of the parameters in the distribution of H₀. The distributions of ζ or -21n(ζ) with n=50, 100 and 150 are obtained through Monte Carlo simulations. Compared with the chi-square distribution, they fall in between x²(4) and x²(6), and they are very close to x²(5). A FORTRAN computer program is developed to conduct simulation of the GLR test for 1 ≤ m₀ < m₁ ≤ 5.

The Tensile behaviour of non-uniform fibres and fibrous composites.

Zhang, Yuping, mikewood@deakin.edu.au January 2001 (has links)
This work investigates the tensile behaviour of non-uniform fibres and fibrous composites. Wool fibres are used as an example of non-uniform fibres because they're physical, morphological and geometrical properties vary greatly not only between fibres but also within a fibre. The focus of this work is on the effect of both between-fibre and within-fibre diameter variations on fibre tensile behaviour. In addition, fit to the Weibull distribution by the non-brittle and non-uniform visco-elastic wool fibres is examined, and the Weibull model is developed further for non-uniform fibres with diameter variation along the fibre length. A novel model fibre composite is introduced to facilitate the investigation into the tensile behaviour of fibre-reinforced composites. This work first confirms that for processed wool, its coefficient of variation in break force can be predicted from that of minimum fibre diameters, and the prediction is better for longer fibres. This implies that even for processed wool, fibre breakage is closely associated with the occurrence of thin sections along a fibre, and damage to fibres during processing is not the main cause of fibre breakage. The effect of along-fibre diameter variation on fibre tensile behaviour of scoured wool and mohair is examined next. Only wet wool samples were examined in the past. The extensions of individual segments of single non-uniform fibres are measured at different strain levels. An important finding is the maximum extension (%) (Normally at the thinnest section) equals the average fibre extension (%) plus the diameter variation (CV %) among the fibre segments. This relationship has not been reported before. During a tensile test, it is only the average fibre extension that is measured. The third part of this work is on the applicability of Weibull distribution to the strength of non-uniform visco-elastic wool fibres. Little work has been done for wool fibres in this area, even though the Weibull model has been widely applied to many brittle fibres. An improved Weibull model incorporating within-fibre diameter variations has been developed for non-uniform fibres. This model predicts the gauge length effect more accurately than the conventional Weibull model. In studies of fibre-reinforced composites, ideal composite specimens are usually prepared and used in the experiments. Sample preparation has been a tedious process. A novel fibre reinforced composite is developed and used in this work to investigate the tensile behaviour of fibre-reinforced composites. The results obtained from the novel composite specimen are consistent with that obtained from the normal specimens.

Optimization of the sample size for Weibull sequential test plan

Vujanović, Nikola Mihajilo, 1946- January 1975 (has links)
No description available.

On the Weibull distribution

Sommers, Dan J. January 1976 (has links)
This work involves the comparisons of various estimates of the parameters of the Weibull distribution. These estimates have been obtained by using various statistical techniques, such as the method of maximum likelihood estimation, the method of moments, etc. The importance, history, practical applications, and characteristics of the Weibull distribution have also been discussed.Computer programs have been developed and included to compare the various estimates. These computer programs were run on an IBM System 360.

Third order likelihood based inference for the log-normal and the Weibull models /

Tarng, Chwu-Shiun. January 2006 (has links)
Thesis (Ph.D.)--York University, 2006. Graduate Programme in Economics. / Typescript. Includes bibliographical references (leaves 137-141). Also available on the Internet. MODE OF ACCESS via web browser by entering the following URL: http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pqdiss&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:NR19821

A simulation study of the error induced in one-shine reliability confidence bounds for the Weiball distribution using a small sample size with heavily censored data /

Hartley, Michael A. January 2004 (has links) (PDF)
Thesis (M.S. in Applied Science)--Naval Postgraduate School, Dec. 2004. / Thesis Advisor(s): David H. Olwell. Includes bibliographical references (p. 57). Also available online.

Generalized reliability methodology applied to brittle anisotropic single crystals /

Salem, J. A. January 1999 (has links)
Thesis (Ph. D.)--University of Washington, 1999. / Vita. Includes bibliographical references (leaves 153-163).

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