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This paper presents an improved magnetic equivalent circuit (MEC) method for modeling linear permanent-magnet synchronous motors (LPMSMs) with adjustable accuracy. The performance of machine with different dimensions, poles and slot numbers can be studied by the proposed flexible MEC, where the core nonlinearity is fitted on the material B–H curve. End effect is modeled by considering two virtual zones with desired accuracy at both entrance and exit ends of the primary. A new structure based on magnets segmentation is also proposed to investigate its effect on the motor performance. Finally, the results of the proposed method are compared with 3D-FEM to show the effectiveness of the presented model. The results show improvement in processing time with good accuracy compared to previous classic methods. In general, introducing a new model based on an improved MEC approach for modeling LPMSMs considering slot effect, iron core saturation and segmented PMs with flexible accuracy by adjusting the number of flux tubes is the paper novelty which is studied in this work. [ABSTRACT FROM AUTHOR]

Light is confined transversely and delivered axially in a waveguide. However, waveguides are lossy static structures whose modal characteristics are fundamentally determined by their boundary conditions. Here we show that unpatterned planar waveguides can provide low-loss two-dimensional waveguiding by using space-time wave packets, which are unique one-dimensional propagation-invariant pulsed optical beams. We observe hybrid guided space-time modes that are index-guided in one transverse dimension and localized along the unbounded dimension. We confirm that these fields enable overriding the boundary conditions by varying post-fabrication the group index of the fundamental mode in a 2-μm-thick, 25-mm-long silica film, achieved by modifying the field's spatio-temporal structure. Tunability of the group index over an unprecedented range from 1.26 to 1.77 is verified while maintaining a spectrally flat zero-dispersion profile. Our work paves the way to utilizing space-time wave packets in on-chip platforms, and enable phase-matching strategies that circumvent restrictions due to intrinsic material properties. Waveguides typically function by using boundary conditions to contain light. Here, the authors show that by using space-time wavepackets, light can be guided in an unpatterned planar waveguide as the field remains localized along the unbounded dimension. [ABSTRACT FROM AUTHOR]

The insulation hot spot temperature (HST) represents the most important limiting factor of a transformer insulation life. Ambient temperature involved in the HST computations in all transformer thermal models affects insulation life-time directly or indirectly. Regarding the importance of the ambient temperature in transformer's insulation life, in this paper a new thermal model for the estimation of HST in transformers has been proposed and using this thermal model, the effect of the ambient temperature on HST and transformer insulation life is investigated. The proposed model has been validated using real data gathered from a 180 MVA transformer. [ABSTRACT FROM AUTHOR]