Sharif Digital Repository

Switched reluctance machines (SRMs) suffer from ultra-low-frequency torque ripple in single pulse mode. This ripple is the result of an imbalance in phase currents, when multiphase excitation occurs. This paper investigates the origin of this imbalance and identifies the imbalanced phase. Excitation shifting strategy, which delays excitation of the imbalanced phase, is then proposed. The delay angle adjusts current amplitude in the imbalanced phase to attain a perfect balance between all phases. The excitation shifting strategy is a general solution, which is applicable to both three-phase and four-phase machines. In addition, the proposed method can be implemented by a much simpler drive... 

Using a simple nonlinear model based on rate equations, and by employing a harmonic balance method, we develop a theory of optimal mixing in directly modulated semiconductor laser diodes. We perform a consistent numerical solution to the mixing in laser diodes to the arbitrary accuracy and intermodulation index (m, n). Through numerical computations we demonstrate that there is an optimal bias in mixing, corresponding to a relaxation frequency, fr, coinciding with the subcarrier frequency, f1, at which the mixing power is maximized nearly simultaneously for all intermodulation products, fmn. In terms of increasing the signal's current amplitude, it will be shown that it would result in a... 

Introduction: Some tinnitus subjects habituate to their tinnitus but some others do not and complain of its annoyance tremendously. Normal sensory memory and change detection processes are needed for detecting the tinnitus signal as a prediction error and habituation to tinnitus. The purpose of this study was to compare auditory mismatch negativity as the index of sensory memory and change detection among the studied groups to search for the factors involving in the perception of tinnitus and preventing habituation in decompensated tinnitus subjects. Methods: Electroencephalography was recorded from scalp electrodes in compensated tinnitus, decompensated tinnitus, and no tinnitus control...