in the current work, ethylene polymerization was investigated from a mathematical modeling point of view. the initiation (activation), propagation, termination, and deactivation reactions were taken into account and the relevant equations used in the modeling were obtained from the elementary reactions. some assumptions including neglecting the transfer and deactivation reactions were considere...

supported catalysts synthesized via the interaction of mg(oet)2 with ticl4 in the presence or absence of an internal stereoregulating donor (di-n-butyl phthalate), with different solvents (chlorobenzene, n-undecane, n-heptane) at different titanation temperatures have been studied by a set of physicochemical methods. data on the chemical composition, x-ray structure and pore structure of these ...

In this paper, the gravitational search algorithm (GSA) is proposed as a method for controlling opening and closing of airplane wing tires. The GSA used to find optimum proportional-integral-derivative (PID) controller, which controls tires during take-off landing. addition, suggested an approach overcoming absence transfer function, usually required design PID. use expected improve system. Two...

After five decades of largely serendipitous (albeit formidable) progress, catalyst design in Ziegler-Natta olefin polymerization, i.e., the rational implementation of new active species to target predetermined polyolefin architectures, has ultimately become a realistic ambition, thanks to a much deeper fundamental understanding and major advances in the tools of computational chemistry. In this...

Ziegler-Natta catalysis is a very important industrial process for the production of polyolefins. However, the catalysts are not well-understood at the molecular level. Yet, atomic-scale structural information is of pivotal importance for rational catalyst development. We applied a solid-state NMR/density functional theory tandem approach to gain detailed insight into the interactions between t...

In a typical lexical decision task, participants are asked to categorize visually presented letter strings as either existing words or as “nonwords”. The most straightforward findings in lexical decision studies are (1) that high frequency words (“house”, “girl”) and nonwords which are not similar to existing words (“yebe”) are responded to more accurately than low frequency words (“chute”, “li...

Let fn−1(P ) denote the number of facets of a polytope P in R . We show that there exist 0/1 polytopes P with fn−1(P ) ≥ ( cn log n )n/2 where c > 0 is an absolute constant. This improves earlier work of Bárány and Pór on a question of Fukuda and Ziegler.

We describe the Ziegler spectrum of a Bézout domain B = D + XQ[X] where D is a principal ideal domain and Q is its field of fractions; in particular we compute the Cantor–Bendixson rank of this space. Using this, we prove the decidability of the theory of B-modules when D is “sufficiently” recursive.

Department of Animal Biology, University of Illinois, 505 S Goodwin Avenue, Urbana, IL 61801, USA (LLG) Department of Wildlife Ecology and Conservation, 110 Newins-Ziegler Hall, University of Florida, Gainesville, FL 32611, USA (MKO) Illinois Natural History Survey, 607 E Peabody Drive, Champaign, IL 81820, USA (JEH) Department of Ecology and Evolutionary Biology, Corson Hall, Cornell Universit...

In the model theory of modules the Ziegler spectrum, the space of indecomposable pure-injective modules, has played a key role. We investigate the possibility of defining a similar space in the context of G-sets where G is a group.