A new approach to analysing the windup phenomenon and antiwindup protection

The paper provides the analytical relation between the limited and unlimited system response in the time domain under or without the presence of antiwindup protection for the general state-space controller. It is shown that, by using this analytical relation, it is possible to explain simply why the extent of windup (large overshoot and long settling time) crucially depends on the difference between the limited and unlimited process time response during which the system is saturated. The same relation also explains why some controllers experience a strong and others a weaker windup phenomenon and why a suitable antiwindup compensator can reduce the windup effect. © 2001, Taylor & Francis Group, LLC. All rights reserved.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Preparation, Characterization and Properties of Pt-Cu Co-reduced and Pt-on-Cu Skin Type Bimetallic Carbon-Supported (Vulcan XC72) Electrocatalysts

Pt/Cu salt co-reduction and, subsequent reduction of Cu(acac)2 and PtCl2 allows to generate either alloyed Pt-Cu or skin type Pt-on-Cu carbon-supported (20 wt%, Pt:Cu = 50:50 a/o on Vulcan XC72) electrocatalysts. An examination by TEM revealed that the co-reduced Pt-Cu catalyst have well dispersed bimetallic nanoparticles (av. particle size 3.6 nm). The skin type Pt-on-Cu catalyst shows tiny Pt clusters (1-2 nm) decorating the surface of larger Cu particles (6-8 nm). XRD pattern of the co-reduced Pt-Cu catalyst shows weak and broad diffraction peaks consistent with a predominantly alloyed composition (plus a few Pt crystallites). Pattern of the skin type Pt-on-Cu/C catalyst reveals larger nanoparticles and points to the formation of (surface) alloy. SEM/EDAX showed a uniform metal distribution present in both Pt-Cu systems. XPS measurements indicated that in both cases only Pto is present. In co-reduced alloy catalyst a higher amount of Cu2+ was present at the nanoparticle surface (Cuo/ Cu2+ = 0.6), while on the surface of the skin type Pt-on-Cu system Cuo and Cu2+ exist in equal amounts (Cuo/ Cu2+ = 1.0). Both types of Cu containing catalysts have higher mass specific activity in hydrogen oxidation reaction (HOR) than the industrial benchmark Pt/C catalyst. The electrocatalytic properties depend on morphological structure subtleties