The theory of high-gain observers has been developed for about twenty years. This paper is a brief introduction to high-gain observers in nonlinear feedback control, with emphasis on the peaking phenomenon and the role of control saturation in dealing with it. The paper surveys recent results on the nonlinear separation principle, conditional servo compensators, extended high-gain observers, performance in the presence of measurement noise, sampled-data control, and experimental testbeds.

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Polyester matrix composites reinforced using nonwoven coir or oil palm empty fruit bunch fiber mats were manufactured. Fibers were used unmodified, chemically modified by acetylation, or treated with silane or titanate coupling agents. Composite test pieces were exposed to decay fungi in unsterile soil for up to 12 months, along with samples made of unreinforced, or glass fiber reinforced, resin. Water exposure tests were also performed. The effect of such exposure on the mass loss, tensile and flexural properties of the samples was evaluated. Mechanical properties deteriorated as a result of exposure. However, acetylation of fibers, or treatment with silane coupling agent was found to afford a significant degree of protection. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 1322–1330, 2000