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...

An attitude control strategy based on Ziegler-Nichols rules for tuning PD (proportional-derivative) parameters of quadrotor helicopters is presented to solve the problem that quadrotor tends to be instable. This problem is caused by the narrow definition domain of attitude angles of quadrotor helicopters. The proposed controller is nonlinear and consists of a linear part and a nonlinear part. T...

Objective(s): Peptide Receptor Radionuclide Therapy (PRRT) with yttrium-90 (90Y) and lutetium-177 (177Lu)-labelled SST analogues are now therapy option for patients who have failed to respond to conventional medical therapy. In-house production with automated PRRT synthesis systems have clear advantages over manual methods resulting in increasing use in hospital-based radiopharmacies. We report...

In Ziegler (2002), the second author presented a lower bound for the chromatic numbers of hypergraphs KG sS, “generalized r-uniform Kneser hypergraphs with intersection multiplicities s.” It generalized previous lower bounds by Kř́ıž (1992/2000) for the case s = (1, . . . , 1) without intersection multiplicities, and by Sarkaria (1990) for S = ([n] k ) . Here we discuss subtleties and difficulti...