Practical stabilization of a class of uncertain nonlinear systems

In this paper the problem of robust control of a class of nonlinear systems with internal and input channel uncertainties is addressed. The proposed control algorithm reflects the two-level structure of the plant and guarantees the system uniform asymptotic stability with respect to an arbitrary neighbourhood of the nominal system stability point.     

Multiple inheritance systems with exceptions

This paper discusses some problems that arise in knowledge-based intelligent systems using property inheritance as the principal inference mechanism. A few methods that deal with those problems are presented here. They are divided into three groups: those that are based on different forms of non-monotonic logics, algebraic structures, and connectionist networks. Implementational issues concerning inheritance systems are considered with the special emphasis put on parallel methods of computation.     

Adhesives from epichlorohydrin elastomers III. Tertiary amine crosslinked adhesives from epichlorohydrin-ethylene oxide copolymer for bonding metals

The mechanical and dielectric properties of epichlorohydrin-ethylene oxide copolymer (EEOC) reaction products with various tertiary amines were investigated. It was found that vulcanizates could be obtained using both monofunctional and difunctional amines. Basing on the results of dielectric loss tangent, volume resistivity and mechanical damping measurements, the presence of ionic crosslinks in tertiary amine-EEOC reaction products was suggested. The adhesives were formulated based on these materials and the tensile and lap-shear strength of A1–A1 bonds were measured. It was found that tertiary amines, especially triethylenediamine, were better crosslinking agents for adhesives than commonly used 2-mercaptoimidazoline and the particular adhesive composition was selected basing on these results.     

Tunneling current and electroluminescence in InGaN: Zn,Si/AlGaN/GaN blue light emitting diodes

We investigate electrical and optical characteristics of Nichia NLPB-500 double-heterostructure blue light-emitting diodes (LEDs), measured over a wide temperature range from 10 to 300K. Current-voltage characteristics have complex character and suggest involvement of at least two different tunneling mechanisms. The peak energy of the optical emission follows the applied bias for voltages between 2.3–2.6 V and can be tuned in large spectral range from 2.3 up to 2.8 eV (yellow to blue). This behavior can be understood invoking the photon-assisted tunneling model which was previously successfully applied to highly doped GaAs LEDs. Even at the lowest temperatures, light emission still continues while the increase in the series resistance does not exceed a few tens of kΩ, which indicates absence of complete carrier freeze-out. On leave from P.N. Lebedev Physics Institute, Russian Academy of Sciences, Moscow, Russia On leave from High Pressure Research Center, Warsaw, Poland     

On-line estimation of signal and noise parameters with application to adaptive Kalman filtering

This paper presents two algorithms for on-line estimation of the optimal gain of the Kalman filter applied to sensor signals when the signal-to-noise ratio is unknown. First-order spectra of a pure signal and colored measurement noise have been assumed. The proposed adaptive Kalman filtering algorithms have been tested for various spectra of the pure signal and noise, and for various signal-to-noise ratios. The effect of the length of an adaptation step and a sampling frequency on the mean square errors of the pure signal estimation has also been examined. Although the test have been performed for stationary signals, the algorithms presented can also be used successfully for time-varying sensor signals when the signal-to-noise ratios vary very slowly in comparison with the length of the adaptation step.The results are helpful for designers who synthesize optimal linear digital filters for sensor signals with first-order spectra and colored measurement noise. The estimation error curves presented enable designers to determine the noise reduction attainable for particular applications of the adaptive Kalman filtering algorithms.     

The changes of the yield,composition and nutritive value of leaf protein extracted from vetch and cereal mixtures during three years cultivation

Three mixtures of vetch with cereals (rye, triticale and wheat) were grown during three consecutive seasons 1985/86, 1986/87 and 1987/88 and leaf protein concentrates (LPC) were prepared using the standard method. LPC were analysed for their gross composition and amino acid content. True digestibility (TD) and biological value (BV) of LPC proteins were estimated on rats using the Thomas-Mitchell balance method. There were no statistical differences in green matter and dry matter yield in the course of the whole experiment. However, in the first season (1986) the yield of vetch × rye mixture was apparently higher and that of the other two mixtures was lower than in the next two years. The protein content of LPC in 1986 was lowest, especially in the concentrates obtained from the triticale and wheat mixtures. There were only small differences in amino acid composition of proteins and these differences did not depend on the year of cultivation or species of cereal used. BV of protein extracted from the rye-containing mixtures was always lower than that of other preparations (means of three years: rye 40, triticale 46, wheat 49). Protein extracted in 1987 had the highest BV. It can be concluded that the season of cultivation affects the green and dry matter yield of legume x cereal mixtures though these differences are levelled off during long-term experiments. The LPC quality is affected both by the kind of cereal and year of cultivation.     

Effect of various dietary fats and proteins on serum cholesterol level in rats

A 60 day experiment on growing rats was performed to evaluate the effect of two protein sources (casein and soybean protein isolate) and four fats (olive oil, OO; evening primrose oil, EO; linseed oil, LO; and butter, B) on plasma lipoprotein fractions: total cholesterol (TC), high‐density lipoprotein cholesterol (HDL‐C), low‐density lipoprotein cholesterol (LDL‐C) and triacylglycerol (TAG) levels. The different protein and fat sources had no influence on body weight gain of rats. Fats had no significant effect on TC and LDL‐C. Significant differences were found only in HDL‐C. OO gave the lowest (43.3 mg dl^?1) and EO the highest (54.4 mg dl^?1) value. Proteins had a significant influence on all lipids analysed. Soybean protein caused higher TC (78.5 vs 67.9 mg dl^?1), HDL‐C and TAG levels but significantly lowered LDL‐C in the plasma of rats. These results suggest that protein has a stronger effect on cholesterol level than fat. © 2002 Society of Chemical Industry