Learning control is a new approach to the problem of skill refinement for robotic systems by repetitive training. A class of simple learning control algorithms with a forgetting factor and without use of the derivative of velocity signals for motion control of robot manipulators is proposed and the convergence property is discussed. The robustness of such a learning control scheme with respect to initialization errors, disturbances, and measurement noise is studied extensively. It is proved that motion trajectories converge to a neighborhood of the desired one and eventually remain in it. In the argument the passivity of robot dynamics and displacement robot dynamics plays a fundamental role. Relations of the size of attraction neighborhoods with the magnitudes of initialization errors and other disturbances are obtained, which suggests a rule for selection of the forgetting factor in the progress of learning. Based on these results, two classes of learning control called "interval training" and "selective learning" are proposed in order to accelerate the speed of convergence.

Even though coding theory applications in fault tolerant computing started with Hamming code invention, their developments were made almost independently from those in information and communication theories after this initiation. This paper gives a brief overview on coding theory applications in fault tolerant computing. A more detailed survey was made on the most important recent developments. Since there are many items of mutual interest to engineers in both fields, mutual stimulations and cooperations between them would be highly appreciated for future mutual developments in coding theory applications.

A nonlinear dynamic circuit model is proposed to represent the differential-algebraic equations arising from the analysis of power system transient stability. By using the circuit-theoretic model, the following results are obtained. (1) Conditions are derived for the existence of Hamiltonian formulation of power systems. (2) A formula for calculating the critical reclosing time is derived using the Hamiltonian. (3) Conditions are obtained for the power system to reach synchronism asymptotically.

A trimming technique for the active RC filter is proposed. This method requires only once of the measurement of initial filter response to find the trimming resistance values. The features of this method are that the roughly selected initial element values are acceptable and the resulting trimming resistance values always increase, which is convenient for the usual laser trimming system.