Search results for "Weibull distribution"
showing 10 items of 42 documents
Influence of the MgO barrier thickness on the lifetime characteristics of magnetic tunnelling junctions for sensors
2016
Magnetic tunnelling junctions increasingly enter the market for magnetic sensor applications. Thus, technological parameters such as the lifetime characteristics become more and more important. Here, an analysis of the lifetime characteristics of magnetic tunnelling junctions using the Weibull statistical distribution for CoFeB/MgO/CoFeB junctions is presented. The Weibull distribution is governed by two parameters, the characteristic lifetime η of the population and the shape parameter β, which gives information about the presence of an infant mortality. The suitability of the Weibull distribution is demonstrated for the description of dielectric breakdown processes in MgO-based tunnelling…
Interfacial shear strength of flax fibers in thermoset resins evaluated via tensile tests of UD composites
2012
Abstract A method of interfacial shear strength evaluation, based on the length distribution of fibers pulled out from the tensile fracture surface of an oriented flax-reinforced composite, is applied to composites with vinyl ester and acrylated epoxidized soy oil resin matrices. Two approaches for characterizing the strength of fibers with modified Weibull distribution, fiber fragmentation tests and fiber tension tests, are compared in the analysis of pull-out data. Interfacial shear strength is found to increase by a few percent when loading rate is increased from 1.33% to 8%/min.
Improved model based on the Weibull distribution to describe the combined effect of pH and temperature on the heat resistance of Bacillus cereus in c…
2003
The effect of pH and temperature on the thermal inactivation of different strains of Bacillus cereus was modeled. Inactivation tests were carried out in carrot broth, following a full factorial design at four levels for temperature (from 90 to 105 degrees C, depending on the strain) and pH (6.2, 5.8, 5.2, and 4.7). Individual inactivation curves were analyzed by applying the Weibull model function (with percent discrepancy close to 20% for most cases), and the effects of pH and temperature on the scale parameter (designated D(beta)) and the shape parameter (beta) were also studied. Temperature and pH did not have a significant effect on the shape parameter (beta). The effect of temperature …
The Effect of Taper and Apical Diameter on the Cyclic Fatigue Resistance of Rotary Endodontic Files Using an Experimental Electronic Device
2021
The aim of this study was to analyze the effect of the taper and apical diameter of nickel&ndash
New Lignocellulosic Aristida adscensionis Fibers as Novel Reinforcement for Composite Materials: Extraction, Characterization and Weibull Distributio…
2019
In this research, the Aristida adscensionis fibers (AAFs) were taken out from the plants and its fundamental properties anlayzed for the first time. The AAFs were characterized and compared with other natural fibers by the use of physico-chemical analysis and various characterization techniques such as FT-IR, XRD, NMR, TGA, SEM and AFM. Chemical analysis showed that A. adscensionis fibers have a high cellulose content of 70.78% whereas the contents of lignin and wax are equal to 8.91% and 2.26%, respectively. The FT-IR, XRD and NMR analysis confirmed that AAFs are rich in cellulose content with CI and CS equal to 58.9% and 11.5 nm, respectively. Pycnometer analysis allowed to estimate a den…
Partial Discharges analysis and parameters identification by continuous Ant Colony Optimization
2008
The technique of ant colony optimization has been employed in this paper to efficiently deal with the problem of parameters identification in partial discharge, PD, analysis. The latter is a continuous optimization problem. From the technical point of view the identification of these parameters allows the modeling of the phenomenon of Partial Discharges in dielectrics. In this way it is possible the early diagnosis of defects in Medium Voltage cable lines and components and thus it is possible to prevent possible outages and service interruptions. Analytically, the problem consists of finding the Weibull parameters of the Pulse Amplitude Distribution (PAD) distributions allowing the identif…
Influence of the Pecking Motion Frequency on the Cyclic Fatigue Resistance of Endodontic Rotary Files
2019
This article belongs to the Special Issue Innovations in Endodontic Dentistry.
Weibull Model for Dynamic Pricing in e-Business
2011
As is the case with traditional markets, the sellers on the Internet do not usually know the demand functions of their customers. However, in such a digital environment, a seller can experiment different prices in order to maximize his profits. In this paper, we develop a dynamic pricing model to solve the pricing problem of a Web-store, where seller sets a fixed price and buyer either accepts or doesn’t buy. Frequent price changes occur due to current market conditions. The model is based on the two-parameter Weibull distribution (indexed by scale and shape parameters), which is used as the underlying distribution of a random variable X representing the amount of revenue received in the sp…
A family of weakest link models for fiber strength distribution
2007
It is well known that the most widely used distribution function for fiber tensile strength, the two-parameter Weibull distribution, does not always adequately describe the experimentally observed fiber strength scatter and the strength dependence on fiber length. To remedy this discrepancy, modifications of the Weibull distribution have been proposed that, while providing a good empirical fit to the strength data, sometimes lack the theoretical appeal of the weakest link models. We derive a family of weakest link models based on the assumption of a two-stage failure process incorporating explicitly the probabilities of flaw initiation and the fiber fracture due to the largest flaw (i.e. th…
Generalized feed-forward based method for wind energy prediction
2013
Abstract Even though a number of new mathematical functions have been proposed for modeling wind speed probability density distributions, still the Weibull function continues to be the most commonly used model in the literature. Therefore, the parameters of this function are still widely used to obtain typical wind probability density distributions for finding the wind energy potential by researchers, engineers and designers. Once long-term average of Weibull function’s parameters are known, then the probability density distributions can easily be obtained. Artificial neural network (ANN) can be used as alternative to analytical approach as ANN offers advantages such as no required knowledg…