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1. MVDC Bipolar Power Cables with Rectangular Geometry Design for Envisaged All-Electric Wide-Body Aircraft

   https://doi.org/10.1109/TPEC60005.2024.10472255  

   Saha, Anoy; Ghassemi, Mona (February 2024, 2024 IEEE Texas Power and Energy Conference (TPEC))

   Designing power cables that provide high power and low system mass is one of the major goals in achieving the future all-electric wide-body aircraft. Radiative and convective heat transfers from a cable's surface to the surrounding air determine how much current is permitted to flow through it. At a cruising altitude of 12.2 km (18.8 kPa) for wide-body aircraft, the limited heat transfer by convection poses thermal issues for the design of aircraft cables. These thermal challenges are exacerbated for bipolar electric power systems (EPS), which are usually made up of two power lines next to each other. The cable's surface area affects both convective and radiative heat transfers. Changing the shape of the cable is one technique to improve heat transfers and compensate for the reduced convective heat transfer caused by low air pressure. In comparison to cylindrical and cuboid cables, the rectangular geometry design gives a bigger contact area with the surrounding atmosphere for the same cross-section area, hence it is anticipated that the heat transfer would rise and as a result, the cable's maximum power-carrying capability will be higher. The purpose of this paper is to design ±5 kV bipolar MVDC power cables with rectangular geometry to raise the maximum current carrying capacity of the cable and analyze its performance with bipolar cylindrical and cuboid geometries. 

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2. Impact of Frequency on the Breakdown Voltage in Litz Wire Under Square Wave Excitation

   https://doi.org/10.1109/CEIDP61707.2025.11218408  

   Erina, Nurun Nahar; Saha, Anoy; Ghassemi, Mona (September 2025, IEEE)

   Wide bandgap (WBG) and ultra-wide bandgap (UWBG)-based inverters are increasingly being adopted in More Electric Aircraft (MEA) and All Electric Aircraft (AEA) due to their ability to operate at higher switching frequencies with improved efficiency and power density. However, these advantages come with drawbacks, including increased electrical stress and exacerbation of AC losses, such as the skin effect and proximity effect. Litz wire, known for its effectiveness in mitigating these losses, is becoming a preferred conductor in highvoltage, high-frequency aerospace applications. This study investigates the breakdown voltage behavior of Litz wire insulation under square wave voltage stress across different frequencies. Twisted-pair Litz wire specimens were tested using a state-of-the-art high-voltage pulse generator with fixed rise times to emulate inverter-fed conditions. The resulting breakdown voltages were statistically analyzed using the Weibull distribution to evaluate insulation strength and failure predictability. The findings offer new insights into the insulation characteristics of Litz wire under realistic high-frequency converter stress and support the development of converter-resistant insulation systems for next-generation aerospace electrical power systems (EPS). 

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3. An Examination of Geomagnetic Induction in Submarine Cables

   https://doi.org/10.1029/2023SW003687  

   Boteler, David H; Chakraborty, Shibaji; Shi, Xueling; Hartinger, Michael D; Wang, Xuan (February 2024, Space Weather)

   Abstract Submarine cables have experienced problems during extreme geomagnetic disturbances because of geomagnetically induced voltages adding or subtracting from the power feed to the repeaters. This is still a concern for modern fiber‐optic cables because they contain a copper conductor to carry power to the repeaters. This paper provides a new examination of geomagnetic induction in submarine cables and makes calculations of the voltages experienced by the TAT‐8 trans‐Atlantic submarine cable during the March 1989 magnetic storm. It is shown that the cable itself experiences an induced electromotive force (emf) and that induction in the ocean also leads to changes of potential of the land at each end of the cable. The process for calculating the electric fields induced in the sea and in the cable from knowledge of the seawater depth and conductivity and subsea conductivity is explained. The cable route is divided into 9 sections and the seafloor electric field is calculated for each section. These are combined to give the total induced emf in the cable. In addition, induction in the seawater and leakage of induced currents through the underlying resistive layers are modeled using a transmission line model of the ocean and underlying layers to determine the change in Earth potentials at the cable ends. The induced emf in the cable and the end potentials are then combined to give the total voltage change experienced by the cable power feed equipment. This gives results very close to those recorded on the TAT‐8 cable in March 1989. 

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4. Abrasion Effect on Heating Performance of Carbon Nanotube/Epoxy Composites

   https://doi.org/10.3390/nano15050337  

   Kim, Byung-Wook; Lee, Seung-Jun; Jang, Sung-Hwan; Yin, Huiming (March 2025, Nanomaterials)

   The effects of abrasion on the heating performance of carbon nanotube (CNT)/epoxy composites were investigated in terms of Joule’s heat, convective heat, and radiative heat under moderate-to-severe and localized abrasive conditions. While the overall heating behavior was characterized by the heating rate and the curvature of the transient response, a numerical solution of the heat equation was used to quantify convective and radiative heat transfers, incorporating the specific heat of each component, the convective heat transfer coefficient, and the Biot number. CNT reinforcement significantly improved wear resistance at a CNT concentration of 0.31 vol. %, but the presence of micro-voids led to a slight increase in wear rate with additional CNT inclusion. Using an equivalent circuit model, local and severe abrasion scenarios were analyzed to determine the variation in electrical conductivity with temperature at different degrees of abrasion, indicating the impact of scattering effects. This analysis provides valuable insights for estimating both wear resistance and the heating performance of self-heated surface materials, with potential applications in future space technologies. 

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5. Influence of Wideband Cable Model for Electric Vehicle Inverter–Motor Connections: A Comparative Analysis

   https://doi.org/10.3390/machines13030189  

   Arafat, Easir; Ghassemi, Mona (March 2025, Machines)

   Electric vehicles (EVs) rely on robust inverter-to-motor connections to ensure high-efficiency operation under the challenging conditions imposed by wide-bandgap (WBG) semiconductors. High switching frequencies and steep voltage rise times in WBG inverters lead to repetitive transient overvoltages, causing insulation degradation and premature motor winding failure. This study proposes a wideband (WB) model of EV cables, developed in EMTP-RV, to improve transient voltage prediction accuracy compared to the traditional constant parameter (CP) model. Using a commercially available EV-dedicated cable, the WB model incorporates frequency-dependent parasitic effects calculated through the vector fitting technique. The motor design is supported by COMSOL Multiphysics and MATLAB 2023 simulations, leveraging the multi-conductor transmission line (MCTL) model for validation. Using practical data from the Toyota Prius 2010 model, including cable length, motor specifications, and power ratings, transient overvoltages generated by high-frequency inverters are studied. The proposed model demonstrates improved alignment with real-world scenarios, providing valuable insights into optimizing insulation systems for EV applications. 

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