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1.
Sensors (Basel) ; 22(19)2022 Oct 03.
Article in English | MEDLINE | ID: mdl-36236599

ABSTRACT

The B-dot sensor is a type of Rogowski coil widely used in the measurement of current. However, the accuracy of the B-dot for measuring aircraft high-frequency lightning current is greatly affected by factors such as numerical integration drift, high-frequency oscillation, and calibration. In this study, a new design and optimization for improving the B-dot measuring accuracy was carried out. To correct the drift of the numerical integral of the measurement signal in differential mode, the measuring current was reconstructed based on the nonlinear least squares method. The sensor was then optimized by isolating the sampling resistance and matching the impedance with a voltage follower. A low-cost coaxial loop calibration system was also designed to calibrate the high frequency and strong magnetic fields more accurately. Finally, the optimized B-dot sensor accuracy was greatly improved with a measuring range of 30 kA/m, an error of 3.1%, and a high-frequency response of 50 MHz. Our study greatly increases the accuracy of measuring aircraft high-frequency lightning current.

2.
Opt Express ; 17(26): 23843-50, 2009 Dec 21.
Article in English | MEDLINE | ID: mdl-20052094

ABSTRACT

Spectrum control by anisotropy in a cylindrical microcavity made of electric anisotropic medium was studied. A finite-difference time domain method for electric anisotropic medium and Volume-average Effective Permittivity approximation are applied to calculate the resonant frequencies and quality factors of Whispering-gallery modes. The resonant frequency for different whispering-gallery modes has a similar shift in direct proportion to the relative difference of two principal refractive indices. The quality factors decay exponentially due to directional emission when the difference of two principal refractive indices increases. This novel tuning characteristic of anisotropic cylindrical microcavity will play an important role in many areas, such as light source with tunable wavelength, tunable filter and sensor.


Subject(s)
Optical Devices , Refractometry/instrumentation , Surface Plasmon Resonance/instrumentation , Computer-Aided Design , Equipment Design , Equipment Failure Analysis , Miniaturization
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