Stochastic order relations among parallel systems from Weibull   distributions
  In this article, we focus on stochastic orders to compare the magnitudes of two parallel systems from Weibull distributions when one set of scale parameters majorizes the other. The new results obtained here extend some of those proved by Dykstra et al. (1997) and Joo and Mi (2010) from exponential to Weibull distributions. Also, we present some results for parallel systems from multiple-outlier Weibull models. 
Nuria Torrado and Subhash C. Kochar
math.ST stat.TH