We present an automated method to identify high‐frequency geomagnetic disturbances in ground magnetometer data and classify the events by the source of the perturbations. We developed an algorithm to search for and identify changes in the surface magnetic field, d
- NSF-PAR ID:
- 10335732
- Date Published:
- Journal Name:
- Journal of Instrumentation
- Volume:
- 16
- Issue:
- 12
- ISSN:
- 1748-0221
- Page Range / eLocation ID:
- P12041
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Abstract B /dt , with user‐specified amplitude and timescale. We used this algorithm to identify transient‐large‐amplitude (TLA) dB /dt events that have timescale less than 60 s and amplitude >6 nT/s. Because these magnetic variations have similar amplitude and time characteristics to instrumental or man‐made noise, the algorithm identified a large number of noise‐type signatures as well as geophysical signatures. We manually classified these events by their sources (noise‐type or geophysical) and statistically characterized each type of event; the insights gained were used to more specifically define a TLA geophysical event and greatly reduce the number of noise‐type dB /dt identified. Next, we implemented a support vector machine classification algorithm to classify the remaining events in order to further reduce the number of noise‐type dB /dt in the final data set. We examine the performance of our complete dB /dt search algorithm in widely used magnetometer databases and the effect of a common data processing technique on the results. The automated algorithm is a new technique to identify geomagnetic disturbances and instrumental or man‐made noise, enabling systematic identification and analysis of space weather related dB /dt events and automated detection of magnetometer noise intervals in magnetic field databases. -
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Abstract We report on the utility of Radiofrequency Amplification by Stimulated Emission Radiation (RASER) for background‐free proton detection of hyperpolarized biomolecules. We performed hyperpolarization of ≈0.3 M ethyl acetate via pairwise parahydrogen addition to vinyl acetate. A proton NMR signal with signal‐to‐noise ratio exceeding 100 000 was detected without radio‐frequency excitation at the clinically relevant magnetic field of 1.4 T using a standard (non‐cryogenic) inductive detector with quality factor of
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Abstract The rapid changes of magnetic fields associated with large, isolated magnetic perturbations with amplitudes |Δ
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1088/1748-0221/16/12/p12041
