W.R. Mead 1915–2014

Long - term photometry of the Wolf - Rayet stars WR 137 , WR 140 , WR 148 , and WR 153 ⋆

In 1991, a long term UBV -photometry campaign of four Wolf-Rayet stars was started using the 60 cm telescope of the National Astronomical Observatory Rozhen, Bulgaria. Here we report on our observational results and discuss the light variations. The star WR137 was observed during 1991 1998. No indications of eclipses were found, though random light variations with small amplitudes exist, which ...

Stellar wind bubbles around WR and [WR] stars

We study the dynamics of stellar wind bubbles around hydrogen-deficient stars using numerical simulations with timeand ion dependent cooling. We consider two types of hydrogen-deficient stars, massive WR stars, producing Ring Nebulae, and low mass [WR] stars, producing Planetary Nebulae. We show that for the Planetary Nebulae, the different cooling properties of the hydrogen-deficient wind lead...

MEAD Documentation v3.10

Grid Restrained Nelder-Mead Algorithm

Probably the most popular algorithm for unconstrained minimization for problems of moderate dimension is the Nelder-Mead algorithm published in 1965. Despite its age only limited convergence results exist. Several counterexamples can be found in the literature for which the algorithm performs badly or even fails. A convergent variant derived from the original Nelder-Mead algorithm is presented....

Klug 5 Rxwh Wr

In this paper, I present a solution to the Doomsday argument (DA, for short) based on a third type of solution, by contrast to on the one hand, the Carter-Leslie view and on the other hand, the EckhardtSowers-Sober analysis. The present line of thought is based on the fact that both aforementioned analyses are based on an inaccurate analogy. After discussing the imperfections of both models, I ...