Summary: A series of 7 homogeneous ethylene‐propylene copolymers is modeled by a Bernoullian, a terminal, a penultimate and a third order Markov model and it is found that the penultimate model describes this series best. The Bernoullian and terminal model prove to be insufficient and the third order Markov model is statistically not justified. Based on these results, a criterion to select the optimal Markovian order of homogeneous, single site catalyst produced copolymers is developed.
Schematic of the [(3‐MePh)(4‐MePh)C(2,7‐di‐tert‐BuFlu)(Cp)]ZrCl2 metallocene copolymerizing ethene and propene. 相似文献
Due to the practical importance of stochastic project networks (PERT-networks), many methods have been developed over the past decades in order to obtain information about the random project completion time. Of particular interest are methods that provide (lower and upper) bounds for its distribution, since these aim at balancing efficiency of calculation with accuracy of the obtained information.We provide a thorough computational evaluation of the most promising of these bounding algorithms with the aim to test their suitability for practical applications both in terms of efficiency and quality. To this end, we have implemented these algorithms and compare their behavior on a basis of nearly 2000 instances with up to 1200 activities of different test-sets. These implementations are based on a suitable numerical representation of distributions which is the basis for excellent computational results. Particularly a distribution-free heuristic based on the Central Limit Theorem provides an excellent tool to evaluate stochastic project networks. 相似文献