The Weibull distribution is widely employed in several areas of engineering because it is an extremely flexible distribution with different shapes. Moreover, it can include characteristics of several other distributions. However, successful usage of Weibull distribution depends on estimation accuracy for three parameters of scale, shape and location. This issue shifts the attentions to the requ...

The Weibull function is frequently chosen to define psychometric functions. Tyler and Chen (Vis. Res. 40 (2000) 3121) criticised the high-threshold postulate implied by the Weibull function and argued that this function implies the assumption of multiplicative noise. It will be shown in this paper that in fact the Weibull function is compatible with the assumption of additive noise, and that th...

A three-parameter Weibull distribution model was developed and verified to simulate the underlying frequency distributions of observations with missing values through the entire range of observations or near and below detection limit of the monitoring equipment. The corresponding Weibull pseudo-random generator then can be used to estimate and replace the missing observations so that the origin...

A new stochastic fading channel model called cascaded Weibull fading is introduced and the associated capacity is derived in closed form. This model is generated by the product of independent, but not necessarily identically distributed, Weibull random variables (RVs). By quantifying the convergence rate of the central limit theorem as pertaining to the multiplication of Weibull distributed RVs...

In this paper the log-exponentiated-Weibull regression model is modified to allow the possibility that long term survivors are present in the data. The modification leads to a log-exponentiated-Weibull regression model with cure rate, encompassing as special cases the log-exponencial regression and log-Weibull regression models with cure rate typically used to model such data. The models attemp...

the hydrothermal time models have been widely applied to describe the germination responses of seeds to temperature and water potential. in this study, three hydrothermal time models developed on the basis of different statistical distributions (normal, weibull and gumbel) were compared to describe the phalaris minor seed germination. results showed that gumbel (aicc=-762.8) and weibull (aicc=-...

Wind speed is the most important parameter in the design and study of the environmental impact assessment. The wind speed determines the concentration of any toxic pollutant released from any chemical industry. As the wind speed increases the concentration of the toxic pollutant at any location in the environment at any instant of time decreases. It is also known that as the wind speed increase...

Spores of Geobacillus stearothermophilus at two inoculum levels (3 and 6 log colony forming units per gram, cfu/g) were challenged with superheated steam (SS) at a velocity of 0.35 m/s and temperature of 130, 145, 160, and 175C. Tailing was observed in the survivor curves (plots of survival ratios, log( o N N ) against treatment time) as a monotonic upward concavity. Therefore, a non-linear reg...

This study compared seven growth models using body weight measurements from 300 progeny obtained from unselected random bred parents. The study which lasted for 20 weeks was carried out at the University of Maiduguri Livestock Teaching and Research farm. R 2 values for the Asymptote regression, Exponential, Gompertz, Logistic, Monomolecular, Richards and Weibull models were 0.994, 0.935, 0.997,...

BACKGROUND Researchers in the medical sciences prefer employing Cox model for survival analysis. In some cases, however, parametric methods can provide more accurate estimates. In this study, we used Weibull model to analyze the prognostic factors in patients with gastric cancer and compared with Cox. METHODS We retrospectively studied 1715 patients with gastric cancer. Age at diagnosis, gend...