Hysteretic behavior in piezoceramic transducers is investigated theoretically and experimentally. The applicability of the rate-independent generalized Maxwell resistive capacitor (MRC) hysteresis model is established. Methods for MRC and inverse MRC online model identification are developed by first establishing that the MRC and its inverse are the same particular cases of the classical Preisach hysteresis model. This enables use of the extensive mathematical framework that has been developed for Preisach models. A method of incorporating the MRC model in a feed forward control scheme for hysteresis compensation is also presented. Experimental studies on a 1-3 piezoceramic composite support the theoretical developments and their applicability to piezoceramics.
The applicability of and relationship between two rate-independent hysteresis models that have been used to describe hysteresis in piezoceramic transducers are investigated. It is shown that the generalized Maxwell resistive capacitor hysteresis model is a particular case of the classical Preisach hysteresis model. The Preisach function that reduces the Preisach model to the Maxwell resistive capacitor model is derived. It is also shown that the inverse of the Maxwell model is this same particular case of the classical Preisach model. A Maxwell model identification procedure based on Preisach identification principles is formulated. The applicability of the classical Preisach and Maxwell hysteresis models for identifying and simulating piezoceramic dielectric behavior is investigated experimentally via studies on a 1-3 piezoceramic composite. Results indicate that both hysteresis models can accurately represent piezoceramic hysteresis. It is noted that the identified relationship between Preisach and Maxwell hysteresis models may prove useful in a wider range of hysteresis applications than just those involving piezoceramics.
ABSTRACT:Based on the anionic groups which appear in heparin, sulfonated poly(vinyl alcohol) (S-PVA), and carboxymethylated poly(vinyl alcohol) (C-PVA) were synthesized. Cross-linked blendmer (XSC-PVA)s were obtained by mixing two aqueous solutions of the anionic charged PYA, whose degrees of substitution were 25%, respectively, using glutaraldehyde as the cross-linking agent. These XSC-PVA membranes were prepared under various conditions in order to determine a suitable mixing ratio of S-PVA to C-PVA and concentration of cross-linking agent. Effect of amount of cross-linker on permeability and mechanical property of the membranes was also examined.KEY WORDS Sulfonated Poly(vinyl alcohol) I Carboxymethylated Poly-(vinyl alcohol) I Cross-Linked Blendmers I Dialysis Membrane IThe structure of water in membranes is very important when a diffusion takes place through membranes swollen with water. 1 A solute permeation is not taken place in the bound water region that has strong hydrogen bond but in the free water region. Factors that affect to the hydrogen bond of water to the membrane material can be defined as chemical structure of membranes, i.e., hydrogen bonding ability of functional groups.Polar groups such as -S03H, -COOH, -NH2' and -CHO make hydrogen bond with water but have tendency to combine with themselves. This effect weakens the coherence of water cluster, which cause diffusion of solute efficiently. 2 -5 of crystallinity can be controlled with the variation of cross-linking density, and thus it is supposed that owing to these variations the diffusion character of solute through the membrane could be controlled. 6 -11 Two types of modified PV A containing sulfate and carboxylic group were prepared respectively, and they were blended and cross-linked under various conditions to make membranes which can be supplied with a test of dialysis performance, because these cross-linked blendmers showed more improved anticoagulation activity.12 Poly(vinyl alcohol), that has a good membrane property, mechanical strength and easily cross-linkable hydroxy groups, has been widely used as membrane and biomedical material. Cross-linked PV A membrane also has a good hydrophilic character that causes efficiently diffusion of solutes, and the ability of hydrogen bond with water and the degree Polym.
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