Identification and Correction of Artifact in the Measurement of Pulsed Magnetic Fields

AC magnetic flux density meters usually integrate a high-pass filter with a very low cutoff frequency (1–30 Hz) aiming at reducing the effect of slow oscillations. This can distort the actual time domain behavior of magnetic flux density waveforms detectable close to industrial or medical devices, even causing artifact high-amplitude oscillations. This paper proposes a procedure to identify the filter parameters that accurately reproduce its measured frequency behavior and suggests an algorithm to correct, in time domain, the field meter recorded waveform. Identification and correction procedures are extensively tested on magnetic flux density waveforms provided by a system for the generation of standard magnetic fields. Finally, the uncertainty associated with the identification and correction procedure is assessed by means of the Monte Carlo method (MCM). Assuming an overall standard uncertainty associated with the MCM model inputs of 0.3%, a standard uncertainty of 0.75% associated with the mean-square error between measured and reconstructed waveforms is obtained.

[1]  Fabio Freschi,et al.  Exposure of Working Population to Pulsed Magnetic Fields , 2010, IEEE Transactions on Magnetics.

[2]  Luca Giaccone,et al.  Identification and correction of artefact in the measurement of pulsed magnetic fields , 2016, 2016 Conference on Precision Electromagnetic Measurements (CPEM 2016).

[3]  Guidance on determining compliance of exposure to pulsed and complex non-sinusoidal waveforms below 100 kHz with ICNIRP guidelines. , 2003, Health physics.

[4]  Fabio Freschi,et al.  A Simplified Procedure for the Exposure to the Magnetic Field Produced by Resistance Spot Welding Guns , 2016, IEEE Transactions on Magnetics.

[5]  Akimasa Hirata,et al.  On the issues related to compliance of LF pulsed exposures with safety standards and guidelines , 2013, Physics in medicine and biology.

[6]  A. Mariscotti,et al.  Time-domain measurement and spectral analysis of nonstationary low-frequency magnetic-field emissions on board of rolling stock , 2004, IEEE Transactions on Electromagnetic Compatibility.

[7]  John H. Holland,et al.  Adaptation in Natural and Artificial Systems: An Introductory Analysis with Applications to Biology, Control, and Artificial Intelligence , 1992 .

[8]  T. Grandke Interpolation Algorithms for Discrete Fourier Transforms of Weighted Signals , 1983, IEEE Transactions on Instrumentation and Measurement.

[9]  K. Jokela,et al.  ICNIRP Guidelines GUIDELINES FOR LIMITING EXPOSURE TO TIME-VARYING , 1998 .

[10]  Robert Hooke,et al.  `` Direct Search'' Solution of Numerical and Statistical Problems , 1961, JACM.

[11]  T. Loenneker,et al.  “Silent” MRI with soft gradient pulses , 1999, Magnetic resonance in medicine.

[12]  Mario Chiampi,et al.  Set Up and Characterization of a System for the Generation of Reference Magnetic Fields From 1 to 100 kHz , 2007, IEEE Transactions on Instrumentation and Measurement.

[13]  Mario Chiampi,et al.  Uncertainty Estimate Associated With the Electric Field Induced Inside Human Bodies by Unknown LF Sources , 2013, IEEE Transactions on Instrumentation and Measurement.

[14]  K Jokela,et al.  Restricting exposure to pulsed and broadband magnetic fields. , 2000, Health physics.

[15]  M. Borsero,et al.  Analysis of magnetic and electromagnetic field emis sions produced by a MRI device , 2010 .

[16]  Bruce J. Balcom,et al.  Direct measurement of magnetic field gradient waveforms , 2010 .