This paper extends the winding function theory for nonuniform air gap in rotating electric machinery. It shows that the winding function differs from that used in the symmetrical case, although several papers employ the uniform air-gap winding function to study electric motor performance under fault conditions. The extended theory will be particularly helpful in the study of squirrel-cage induction motors with a nonuniform air gap such as that caused by eccentricity of the rotor and stator.

This paper presents a more precise model for computation of three-phase squirrel cage induction machine inductances under different eccentric conditions. Generally, available techniques are based on the winding function theory and simplification and geometrical approximation of unsymmetrical models of the motor under mixed eccentricities. This paper determines a precise geometrical model under the mixed eccentricity conditions and evaluates the inductances. Meanwhile, the evaluated inductances are compared to those calculated using different approximate geometrical models and the best approximation is recommended for a geometrical modeling of induction motor under eccentricity conditions.

Implementation of adaptive active noise control (ANC) systems requires an estimate model of the secondary path to be uploaded onto digital control hardware. In practice, this model is not necessarily perfect; however, to avoid mathematical difficulties, theoretical analysis of these systems is usually conducted for a perfect secondary path model. This paper conducts a stochastic analysis on performance of Filtered-x LMS (FxLMS)-based ANC systems when the actual secondary path and its model are not identical. This analysis results in a number of mathematical expressions, describing effects of a general secondary path model on stability, steady-state performance and convergence speed of FxLMS-based ANC systems. As a surprising result, it is found that intentional misadjustment of secondary path models can enhance performance of ANC systems in practice. Theoretical results are found to be in a good agreement with the results obtained from numerical analysis. Also, experimental results confirm the validity and accuracy of the theoretical results.

RF fingerprinting aims to develop a unique RF fingerprint for a wireless device that can be used as an identity, in the same way a biological fingerprint operates, to improve the security and privacy of wireless communication. This is in contrast to the traditional bit-level algorithmic approaches to securing transmissions. In this work, we present a comprehensive overview of challenges in the deployment of RF fingerprinting in low-cost portable mobile devices including: the preliminary results showing the effect of channel impairments on RF fingerprinting accuracy and open research challenges associated with the deployment of RF fingerprinting.