An official website of the United States government
This content will become publicly available on March 22, 2026
Comparative Analysis of Human Braking Behavior and Automated Regenerative Braking Systems in Electric Vehicles
- Award ID(s):
- 2241718
- PAR ID:
- 10633967
- Publisher / Repository:
- IEEE
- Date Published:
- ISBN:
- 979-8-3315-0484-7
- Page Range / eLocation ID:
- 844 to 849
- Format(s):
- Medium: X
- Location:
- Concord, NC, USA
- Sponsoring Org:
- National Science Foundation
More Like this
-
The evolution of magnetic braking and dynamo processes in subgiant stars is essential for understanding how these stars lose angular momentum. In this work, we investigate the magnetic braking and dynamo evolution of the G-type subgiant β Hyi to test the hypothesis of weakened magnetic braking and the potential rejuvenation of large-scale magnetic fields. We analyzed spectropolarimetric observations from the polarimetric mode of High Accuracy Radial velocity Planet Searcher (HARPSpol) and combined them with archival X-ray data and asteroseismic properties from Transiting Exoplanet Survey Satellite (TESS) to estimate the current wind-braking torque of β Hyi. Despite experiencing weakened magnetic braking during the second half of its main-sequence lifetime, our results indicate that β Hyi has regained significant magnetic activity and a large-scale magnetic field. This observation aligns with the “born-again” dynamo hypothesis. Furthermore, our estimated wind braking torque is considerably stronger than what would be expected for a star in the weakened magnetic braking regime. This suggests that subgiants with extended convective zones can temporarily re-establish large-scale dynamo action. These results provide critical constraints on stellar rotation models and improve our understanding of the interplay between magnetic field structure, stellar activity cycles, and angular momentum evolution in old solar-type stars.more » « less
-
Non-exhaust emissions (e.g., automotive brake and tire wear) are quickly replacing exhaust emissions as the dominant traffic particulate pollutant. A significant fraction of the emissions are complex mixtures of organic compounds whose composition is not well known. Due to their unique health implications, knowledge of the composition of ultrafine particles (<100 nm in diameter) is of particular interest. Here we report on the size-selected organic composition of ultrafine particles nucleated during high brake temperature conditions generated using a custom brake dynamometer system and two common brake pad types. Using high resolution mass spectrometry, we find that the organic composition of these particles is dominated by species containing oxygen (CHO) and nitrogen (CHN/CHON). Many of these compounds are unsaturated and are attributed to the thermal degradation of resin material used in the pad formulation. Other abundant compounds include various glycols and amines, several of which are unequivocally identified and discussed as potential marker compounds for brake wear emissions. A significant fraction of highly oxidized, low volatility species observed in ultrafine particles could not be conclusively attributed to the thermal degradation of the brake material, indicating the presence of chemical pathways unique to the frictional heating process. This emphasizes the importance of using a brake dynamometer to generate brake wear particles as opposed to other strategies.more » « less
