For applications with high torque demand, gearboxes are commonly used to convert torque and speed in order to receive higher specific values for torque and power. This causes additional losses, cost, inaccuracies, effort, and noise. Eliminating the need of a mechanical gear and the associated disadvantages, Transverse Flux Machines with their high torque density are a very promising alternative. Despite a high torque density and a high efficiency, these types of machines are not commonly used. Due to the complex structure, challenges with mechanical design, and modeling of the machine behavior arise. Additionally, there are high requirements for the inverter due to the low power factor. This paper provides an overview of the state of the art including the potentials and advantages but also the problems and hindrances of these types of machines. Relating to linear and rotary machines from research and industry, the machine is introduced with its history, application and classification. Further, the general technical aspects, the influence of materials for flux guidance, the methods of modeling, methods for a minimization of torque ripples, as well as methods for power factor improvement are presented.

This article focuses on increasing the computational efficiency of 3D multi-static magnetic finite element analysis (FEA) for electrical machines (EMs), which have a magnetic field evolving in 3D space. Although 3D FEA is crucial for analyzing these machines and their operational behavior, it is computationally expensive. A novel approach is proposed in order to solve the magnetic field equations by exclusively using the magnetic scalar potential. For this purpose, virtual variable permanent magnets (vPMs) are introduced to model the impact of the machine’s coils. The effect on which this approach is based is derived from and explained by Maxwell’s equations. To validate the new approach, an axial flux machine (AFM) is simulated using both 2D and 3D FEA with the magnetic vector potential and current-carrying coils as a reference. The results demonstrate a high level of agreement between the new approach and the reference simulations as well as an acceleration of the computation by a factor of 15 or even more. Additionally, the research provides valuable insights into meshing techniques and torque calculation for EMs in FEA.

Goal: Skeletal muscle mechanics can be assessed in vivo using shear wave elastography. However, the impact of pennation angle on shear wave velocity (SWV) remains unclear. This study aims to quantify the effect by automatically aligning the ultrasound probe with muscle fiber orientation. Methods: We propose an automatic ultrasound probe alignment system and compare it to manual and no alignment. SWV of the gastrocnemius medialis muscle of ten volunteers was measured during rest and isometric contractions. Results: The SWV was different between the conditions ( $p~=~0.008$ ). The highest SWV was obtained during the automatic alignment and differences between the conditions were most pronounced during high-level contractions. The automatic system yielded more accurate alignment compared to a manual operator ( $p~=~0.05$ ). Conclusions : The present study indicates that pennation angle affects SWV, hence muscle fiber orientation must be considered to reliably interpret SWV. Using automatic alignment systems allows for more accurate alignment, improving the methodology of ultrasound elastography in skeletal muscles.

Magnetocaloric cooling is a refrigerant-free alternative to vapor-compression systems, but rotating-magnet demonstrators are typically limited to about 15 Hz. Prior electro-permanent-magnet (EPM) studies demonstrated efficient high-frequency field sources, but did not determine whether this field-source advantage remains at cooler-system level when the magnetocaloric material, useful cooling power, Carnot work, hysteresis losses, cycle losses, electromagnetic losses, and finite heat extraction are evaluated in one coefficient of performance (COP) framework. This purely simulation-based study addresses that gap for a LaFeSi-based magnetocaloric device by coupling a 2D COMSOL electromagnetic model with post-processing for the first-order thermal low-pass response of the magnetocaloric elements. This avoids full coupled thermo-fluid simulation while retaining the thermal cut-off frequency that limits heat extraction. The model yields losses and useful cooling energy across 1–50 Hz for a field change of at least about 1 T, and the relative COP is evaluated for cut-off frequencies from 4 to 40 Hz while varying sample length and winding area. The maximum relative COP reaches 53.22% at 40 Hz cut-off with a 177.85 cm 2 winding area as a model-based upper-bound estimate, and efficiencies above 50% are achieved at 16 Hz system frequency. Efficiency first increases with frequency, then an optimal operating point emerges; beyond that point the thermal time constant limits heat transfer and the COP declines. These results show that EPM magnetocaloric systems can reach efficiencies comparable to conventional heat pumps only when the magnetic field source and magnetocaloric heat-extraction limits are optimized together.