This paper presents an algorithm based on &nematic oscillator which is used to control four wheel skidsteering mobile robot (4 WD SSMR). This proposition is an extension of original kinematic controller proposed by Dixon and others 141 and it allows to ensure practical stabilization (see works done by Morin and Samson 171) for non-admissible tmjectories. In order to improve robustness of control law dynamical model of SSMR are included by using backstepping technique and Lyapunou analysis. Theoretical results are verified by numerical simulations perfanned in Matlab/Simulink environment.

The critical dose above which a decrease in toughness of Western Red Cedar and Peroba wood, extracted with benzene-alcohol is noted, was determined to be approximately 0.5 • 106 rad lower than that for the same non-extracted species. Investigations have shown that the presence of benzene-Mcohol extractives in wood raises its radiation stability. This conclusion is supported by the fact that the toughness curve which generally falls with increasing doses of absorbed irradiation shows a steeper decrease for extracted than for nonextracted wood.

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