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This work explores an adaptive second-order sliding mode control strategy to maximize the energy production of a wind energy conversion system (WECS) simultaneously reducing the mechanical stress on the shaft. Such strategy successfully deals with the random nature of wind speed, the intrinsic nonlinear behavior of the WECS, and the presence of model uncertainties and external perturbations acting on the system. The synthesized adaptive controller is designed from a modified version of the super-twisting (ST) algorithm with variable gains. The suitability of the proposed strategy is proved by extensive computer-aided simulations employing a comprehensive model of the system emulating realistic conditions of operation, i.e., considering variations in the parameters and including external disturbances. Additionally, a second controller based on the traditional ST algorithm is also designed and simulated. Results are presented and discussed in order to establish a comparison framework. [ABSTRACT FROM PUBLISHER]

Synchronous generators have a natural different time scale dynamics. That is why, for modelling and control design in such systems, the methods of singular perturbations are widely used. In this paper the possibilities of sliding mode control design for synchronous generators are analysed. With this aim the concept of singular perturbation is revised in order to use it for relay control systems. The obtained results are used for sliding mode control of synchronous generator. [ABSTRACT FROM AUTHOR]

Shows that slow periodic solutions of singularly perturbed bang-bang systems (SPBBS) have interior boundary layers appearing in the transition from a neighborhood of one leaf of the integral manifold into a neighborhood of another. Application of the boundary function method; Existence of periodic solutions and of slow periodic motions; Uniqueness of slow periodic motions and their stability; Algorithm for the construction of the asymptotics of a periodic solution.

This work will familiarize the teacher with contemporary Soviet psychology's progress to date in the study and shaping of the motivation to learn. [1] [ABSTRACT FROM AUTHOR]

Of the basic tasks that the Soviet school, and every teacher in it, faces at the present time, none is more important-nor, for that matter, more complex-than that of shaping in pupils a positive and stable motivation toward learning activity, a motivation that will stimulate them to persevering and systematic performance in school. It is, after all, obvious that in the absence of such motivation, pupil activity in the teaching and learning process will be ineffectual. [ABSTRACT FROM AUTHOR]

This article reviews current developments in Soviet mathematical psychology and relates them to the very extensive extant literature in the United States. Programmatic articles of this kind are frequent in Soviet journals. They serve the dual purpose of highlighting current areas of concern and pointing to probable future areas of growth. Mathematics in large doses is now a standard part of the Soviet psychologist's education, and can be counted on to be an important feature of future psychological research. [ABSTRACT FROM AUTHOR]