Fix what ends up cited as "web sources"

main.bib

@@ -8134,6 +8134,7 @@ Archive 2: https://web.archive.org/web/20250510104017/https://de.linkedin.com/pu
   abstract = {Litz wire planar spiral coils are widely used in inductive power transfer systems due to low power loss in high-frequency operation and low profile. However, the complicated structure of the litz wire coil imposes difficulties in estimating the frequency-dependent resistance and quality factor accurately. In this work, we present an 2D analytical model for calculating the frequency-dependent resistance and quality factor of multi-coil inductive power transfer systems based on superposition of different loss effects. Its accuracy is validated with multiple coils and litz wires over wide frequency range. Meanwhile, a fast and accurate multi-objective optimization method is developed to improve the product quality factor and coupling factor. From the optimization results, there are five factors affecting the quality factor and coupling factor. A set of design guidelines is proposed to cope with these design factors. The final prototypes show 33\textbackslash\% increase in quality factor and 23\textbackslash\% improvement in coupling factor compared with the state-of-the-art designs. Meanwhile, a 30W, 500kHz inductive power transfer system is designed with 91\textbackslash\% peak efficiency.},
   langid = {english},
   pubstate = {prepublished},
+  keywords = {preprint},
   file = {/home/jaseg/Zotero/storage/ZAQTS252/Zhao et al. - 2023 - Design and Optimization of Litz-Wire Planar Spiral.pdf}
 }