**Preface**

Electric machines are key components for both power generation and industrial propulsion. Electric machines include not only rotating motors/generators, but also all kinds of electric energy conversion/transformation machines (power transformers, linear motors, etc.). The development tendency of current electric machines is moving towards a larger capacity, higher power density, lower mass, and better strength. This tendency places stricter demands for the stable and reliable operation of the components in electric machines.

Since the unexpected breakdown of electric machines leads to considerable economic loss and even disaster, the condition monitoring and failure prevention of electric machines is pretty significant. With the rapid development of computer science and intelligent technologies, more and more novel monitoring and diagnosis approaches/methods are being developed. To provide a qualified gathering for readers/researchers on this topic, this reprint contains 11 recent studies. The authors are from China, Russia, USA, and Mexico. We believe these 11 recent studies will offer a good reference for scholars and technicians working in the field of electric machine monitoring and failure prevention.

Last but not least, we appreciate the contributors of the 11 articles for their excellent work. Also, we wish to make the following acknowledgements:

National Natural Science Foundation of China (52177042);

The Chinese Fundamental Research Funds for the Central Universities (2023MS128);

The Top Youth Talent Support Program of Hebei Province ([2018]-27);

The Hebei Provincial High-Level Talent Funding Project (B20231006);

The Suzhou Social Developing Innovation Project of Science and Technology (SS202134).

### **Yuling He, David Gerada, Conggan Ma, and Haisen Zhao** *Editors*
