full factorial experimental design (23) for the evaluation of slurry ethylene polymerization in the presence of an industrial ticl4/mgcl2 ziegler-natta catalyst was employed. the following parameters were used as independentvariables: al/ti molar ratio, reaction temperature and hydrogen partial pressure. the total polymerization pressure was 9 bar. catalyst activity, mfi (melt flow index) and m...

The Ziegler Reservoir fossil site near Snowmass Village, Colorado, provides a rare opportunity to examine environmental conditions in the Rocky Mountains during marine isotope stage (MIS) 4 (71–57 ...

In this paper, a fractional order flight controller design scheme for the altitude control of vertical take-off and landing (VTOL) UAV is presented. The altitude control system can be decoupled and identified as a simple first order plus time delay model under some constraints. Based on this identified model, the traditional modified Ziegler-Nichols PI controller can be designed. Meanwhile, the...

Proportional-integral-derivative (PID) controllers are widely used in industrial control systems because of the reduced number of parameters to be tuned. The most popular design technique is the Ziegler–Nichols method, which relies solely on parameters obtained from the plant step response. However, besides being suitable only for systems with monotonic step response, the compensated systems wh...

a linear low density polyethylene (lldpe) production process, including two- fuidized bed reactors in series (fbrs) and other process equipment, was completely simulated by aspen polymer plus software. fluidized bed reactors were considered as continuous stirred tank reactors (cstr consisted of polymer and gas phases). poly-srk and nrtl-rk equations of state were used to describe polymer and no...

in this article, a complete model for the mixed flow slurry reactor for polymerization of ethylene to high density polyethylene in the presence of ziegler-natta catalyst is presented. in addition to the effects of the multiple active sites, the effect of other important parameters such as the catalyst concentration, co-catalyst, hydrogen, monomer, impurities and pressure on the mass-average and...