A Study Using Power Cycling on the Affective Responses of a Low-Volume High-Intensity Interval Training to Male Subjects with Type 2 Diabetes in Different Physical Activity Status

High-intensity interval training (HIIT) has been shown in studies to enhance glucose management and cardiovascular well-being in patients with type 2 diabetes. In this study, we used power cycling to assess the physical activity levels of men with type 2 diabetes during a single low-volume HIIT session. First, fifty-six men with type 2 diabetes volunteered to take part in the study, and they were split into two groups based on the International Physical Activity Scale Short Form (IPA). To the first 1–4 labor bouts, both the sufficiently physically active and insufficiently physically active groups exhibited equal positive emotional reactions ( p > 0.05 ). However, over time (about 5–10 times), both of them showed reduced emotional reactions, with a significant difference ( p < 0.01 ). The insufficiently physically active group had lower mean emotional response, lowest effective response, and maximum effective response values than the sufficiently physically active group ( p < 0.001 ), while the difference in RPE between the two groups was not statistically significant ( p > 0.05 ). From the standpoint of emotional response, the proposed model shows that HIIT or reduced volume HIIT exercise prescriptions should be utilized with caution in physical activity programs for novices and less active and chronically sick persons. The frequency, intensity, and effects of low-volume HIIT on individuals’ emotional reactions and health conditions in the T2DM group are also investigated. Furthermore, this low-volume HIIT program can be successfully applied in the real-world setting of people who are not physically active enough or who are chronically unwell.

Degradation mechanisms analysis for SiC power MOSFETs under repetitive power cycling stress

In this work, investigation on the degradation behavior of the 1.2-kV/52-A silicon carbide (SiC) power MOSFETs subjected to repetitive slow power cycling stress have been performed. Electric characteristics have been characterized periodically over the stress and the respective degradation mechanisms also have been analysed. A comprehensive degradation analysis is further conducted after the aging test by virtue of the X-ray inspection system, Scanning Acoustic Microscope (SAM), Scanning Electron Microscope (SEM) and emission microscope (EMMI), etc. Experimental results reveal that both the degradation of gate oxide on chip-level and the degradation of the bond wire and solder layer on package-level have emerged over the cyclic stress. Specifically, growths of threshold voltage (Vth) and gate leakage current (Igss) are thought to be relevant with the degradation of gate oxide by SiC/SiO2 interface states trapping/de-trapping electron on chip-level, while the appearances of the fatigue of bond wire and the delamination of solder layer imply the degradation on package-level. This work may provide some practical guidelines for the assessments towards the reliability of SiC power MOSFETs in power conversion system.

Cold Gas Spray of Copper on Aluminum Nitride as Substrate for Power Electronics

Ceramic substrates for electronic packaging of high-power applications are growing in demand due to their robustness as power and thermal requirements increase. Aluminum nitride (AlN) has excellent thermal and electrical properties with copper currently being bonded to AlN via a direct bond copper (DBC) technique. However, substrates fabricated by DBC are subjected to thermo-mechanical fatigue during fabrication processes and power cycling. DBC substrate’s reliability is negatively affected by the large mismatch in coefficient of thermal expansion that hinders the possibility of thicker substrates, therefore limiting its use for applications above 20 kV. This work employed cold gas spraying (CGS) to mechanically bond Cu on AlN. CGS is a low-temperature additive manufacturing method that accelerates powder particles at near-supersonic velocities to impact a surface causing plastic deformation and mechanical bonding. On ceramic-metal systems CGS has not been widely studied owing to ceramics’ inability to deform plastically, therefore, surface functionalization was performed to enhance the mechanical interlocking mechanism. A factorial design of experiments (DOE) was used to assess the effect of factors: temperature, pressure, stand-off distance, angle of deposition, and travel speed on various substrate surfaces in the CGS fabrication process. These experiments resulted in a successful deposition of copper on AlN.