scholarly journals Modeling and characterization of PCB coils for inductive wireless charging

2015 ◽  
Vol 2 (2) ◽  
pp. 127-133 ◽  
Author(s):  
Brian Curran ◽  
Uwe Maaß ◽  
Gerhard Fotheringham ◽  
Nobby Stevens ◽  
Ivan Ndip ◽  
...  
Keyword(s):  
Coupling Coefficient ◽  
Design Principles ◽  
Separation Distance ◽  
Receiver Coil ◽  
Wireless Charging ◽  
Quality Factors ◽  
Approach Zero

Wireless charging is emerging as a viable technology in many industries, including consumer, medical, and sensor electronics. An investigation of design principles is conducted for a wireless charging platform that is designed to charge devices of different sizes and technologies, using only through vias. It is shown that at a 5 mm separation distance, a coupling coefficient can be achieved which varies from 0.12 to 0.37 when staggered hexagonal transmitter coils (approximately 5 cm across) are used with an unstaggered square receiver coil, which declines to 0.06–0.11 at 2 cm separation. Without design measures, the coupling coefficient will approach zero at certain positions. The quality factors of the coils can be improved by stacking the coils in parallel, enabling the use of only through-vias, while the inductance can be controlled horizontally by increasing the number of turns in the inductor.

scholarly journals Azimuthal Anchoring Strength in Photopatterned Alignment of a Nematic

Crystals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 675
Author(s):  
H. Nilanthi Padmini ◽  
Mojtaba Rajabi ◽  
Sergij V. Shiyanovskii ◽  
Oleg D. Lavrentovich
Keyword(s):  
Liquid Crystal ◽  
Point Defects ◽  
Elastic Energy ◽  
Separation Distance ◽  
Thin Layers ◽  
Uv Exposure ◽  
Surface Anchoring ◽  
Anchoring Strength ◽  
Spatially Varying

Spatially-varying director fields have become an important part of research and development in liquid crystals. Characterization of the anchoring strength associated with a spatially-varying director is difficult, since the methods developed for a uniform alignment are seldom applicable. Here we characterize the strength of azimuthal surface anchoring produced by the photoalignment technique based on plasmonic metamsaks. The measurements used photopatterned arrays of topological point defects of strength +1 and −1 in thin layers of a nematic liquid crystal. The integer-strength defects split into pairs of half-integer defects with lower elastic energy. The separation distance between the split pair is limited by the azimuthal surface anchoring, which allows one to determine the strength of the latter. The strength of the azimuthal anchoring is proportional to the UV exposure time during the photoalignment of the azobenzene layer.

scholarly journals Development and characterization of Nb3Sn/Al2O3 superconducting multilayers for particle accelerators

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Chris Sundahl ◽  
Junki Makita ◽  
Paul B. Welander ◽  
Yi-Feng Su ◽  
Fumitake Kametani ◽  
...  
Keyword(s):  
High Performance ◽  
High Energy ◽  
Particle Accelerators ◽  
Quality Factors ◽  
Critical Fields ◽  
Linear Accelerators ◽  
Cross Sectional ◽  
Low Field ◽  
Superconducting Radio Frequency

AbstractSuperconducting radio-frequency (SRF) resonator cavities provide extremely high quality factors > 1010 at 1–2 GHz and 2 K in large linear accelerators of high-energy particles. The maximum accelerating field of SRF cavities is limited by penetration of vortices into the superconductor. Present state-of-the-art Nb cavities can withstand up to 50 MV/m accelerating gradients and magnetic fields of 200–240 mT which destroy the low-dissipative Meissner state. Achieving higher accelerating gradients requires superconductors with higher thermodynamic critical fields, of which Nb3Sn has emerged as a leading material for the next generation accelerators. To overcome the problem of low vortex penetration field in Nb3Sn, it has been proposed to coat Nb cavities with thin film Nb3Sn multilayers with dielectric interlayers. Here, we report the growth and multi-technique characterization of stoichiometric Nb3Sn/Al2O3 multilayers with good superconducting and RF properties. We developed an adsorption-controlled growth process by co-sputtering Nb and Sn at high temperatures with a high overpressure of Sn. The cross-sectional scanning electron transmission microscope images show no interdiffusion between Al2O3 and Nb3Sn. Low-field RF measurements suggest that our multilayers have quality factor comparable with cavity-grade Nb at 4.2 K. These results provide a materials platform for the development and optimization of high-performance SIS multilayers which could overcome the intrinsic limits of the Nb cavity technology.

MEMS Microresonators Based on Nanocrystalline Silicon

2004 ◽  
Vol 808 ◽  
Author(s):  
J. Gaspar ◽  
T. Adrega ◽  
V. Chu ◽  
J. P. Conde
Keyword(s):  
Energy Dissipation ◽  
Chemical Vapor ◽  
Nanocrystalline Silicon ◽  
Quality Factors ◽  
Electrostatically Actuated ◽  
Glass Substrates ◽  
Boron Doped ◽  
Resonance Frequencies ◽  
Geometrical Dimensions

ABSTRACTThis paper describes the fabrication and characterization of thin-film nanocrystalline silicon microresonators processed at temperatures below 110°C on glass substrates. The microelectromechanical structures consist of surface micromachined bridges of boron-doped hydrogenated nanocrystalline silicon (p+-nc-Si:H) deposited at 100°C by hot-wire chemical vapor deposition (HWCVD). The microbridges, which are suspended over an Al gate electrode, are electrostatically actuated and the mechanical resonance is detected in vacuum using an optical setup. The resonance frequency and energy dissipation in p+-nc-Si:H based resonators are studied as a function of the geometrical dimensions of the microstructures. Resonance frequencies between 700 kHz and 36 MHz and quality factors as high as 2000 are observed. A Young's modulus of 160 GPa for the structural bridge film is extracted from the experimental data using an electromechanical model and the main intrinsic energy dissipation mechanisms in nc-Si:H microresonators are discussed.

High and Moderate-Level Vacuum Packaging of Vibratory MEMS

2013 ◽  
Vol 2013 (1) ◽  
pp. 000705-000710 ◽  
Author(s):  
Igor P. Prikhodko ◽  
Brenton R. Simon ◽  
Gunjana Sharma ◽  
Sergei A. Zotov ◽  
Alexander A. Trusov ◽  
...  
Keyword(s):  
Vacuum Packaging ◽  
Moderate Level ◽  
Silicon On Insulator ◽  
Quality Factors ◽  
High Q ◽  
Hermetic Sealing ◽  
Hemispherical Resonator ◽  
Q Factors ◽  
Grade Performance

We report vacuum packaging procedures for low-stress die attachment and versatile hermetic sealing of resonant MEMS. The developed in-house infrastructure allows for both high and moderate-level vacuum packaging addressing the requirements of various applications. Prototypes of 100 μm silicon-on-insulator Quadruple Mass Gyroscopes (QMGs) were packaged using the developed process with and without getters. Characterization of stand-alone packaged devices with no getters resulted in stable quality factors (Q-factors) of 1000 (corresponding to 0.5 Torr vacuum level), while devices sealed with activated getters demonstrated Q-factors of 1.2 million (below 0.1 mTorr level inside the package). Due to the high Q-factors achieved in this work, we project that the QMG used in this work can potentially reach the navigation-grade performance, potentially bridging the gap between the inertial silicon MEMS and the state-of-the-art fused quartz hemispherical resonator gyroscopes.

scholarly journals Contribution of a joint Bayesian inversion of VLBI and gravimetric data to the estimation of the free inner core nutation and free core nutation resonance parameters

2020 ◽  
Vol 222 (2) ◽  
pp. 845-860
Author(s):  
Yann Ziegler ◽  
Sébastien B Lambert ◽  
Ibnu Nurul Huda ◽  
Christian Bizouard ◽  
Séverine Rosat
Keyword(s):  
Quality Factor ◽  
Inner Core ◽  
Joint Inversion ◽  
Chandler Wobble ◽  
Bayesian Inversion ◽  
Quality Factors ◽  
Free Core Nutation ◽  
Gravimetric Data ◽  
Vlbi Data

SUMMARY The rotational motions of the internal Earth layers induce resonances in the Earth nutations and tidal gravimetric response to external luni-solar gravitational forcings. The characterization of these resonances is a mean of investigating the deep Earth properties since their amplitudes and frequencies depend on a few fundamental geophysical parameters. In this work, we focus on the determination of the free core nutation and free inner core nutation periods and quality factors from the Bayesian inversion of VLBI and gravimetric data. We make a joint inversion of data from both techniques and show that, even if the results are only slightly different from the inversion of VLBI data alone, such approach may be valuable in the future if the accuracy of gravimetric data increases. We also briefly discuss the polar motion resonance, which is related to the Chandler Wobble as seen from the diurnal frequency band. Our overall estimates of the FCN period and quality factor, TFCN = (−430.2, −429.8) solar days and QFCN = (15 700, 16 700), respectively, are in good agreement with other studies, albeit slightly different for unclear reasons. Despite some concerns about the detection and characterization of the FICN, it seems that we could also successfully estimate its period, TFICN = (+600, +1300) solar days, and give a loose estimate of the upper bound on its quality factor.

scholarly journals Autonomous Coil Alignment System Using Fuzzy Steering Control for Electric Vehicles with Dynamic Wireless Charging

2015 ◽  
Vol 2015 ◽  
pp. 1-14 ◽  
Author(s):  
Karam Hwang ◽  
Jaehyoung Park ◽  
Dongwook Kim ◽  
Hyun Ho Park ◽  
Jong Hwa Kwon ◽  
...  
Keyword(s):  
Fuzzy Control ◽  
Power Delivery ◽  
Receiver Coil ◽  
Wireless Charging ◽  
Steering Control ◽  
The Road ◽  
Voltage Difference ◽  
Alignment System ◽  
Transmitter Coil ◽  
Left Front

An autonomous coil alignment system (ACAS) using fuzzy steering control is proposed for vehicles with dynamic wireless charging. The misalignment between the power receiver coil and power transmitter coil is determined based on the voltage difference between two coils installed on the front-left/front-right of the power receiver coil and is corrected through autonomous steering using fuzzy control. The fuzzy control is chosen over other control methods for implementation in ACAS due to the nonlinear characteristic between voltage difference and lateral misalignment distance, as well as the imprecise and constantly varying voltage readings from sensors. The operational validity and feasibility of the ACAS are verified through simulation, where the vehicle equipped with ACAS is able to align with the power transmitter in the road majority of the time during operation, which also implies achieving better wireless power delivery.

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