A possible preseismic anomaly in the ground wave of a radio broadcasting (216 kHz) during July-August 1998 (Italy)

Abstract. On February 1996, a receiver able to measure the electric field strength of LF radio broadcastings, with a sampling frequency of ten minutes, was put into operation in a site (AS) located in central Italy. One of the broadcasting stations selected is MCO (f=216 kHz), located in southeast France, 518 km far from the receiver. The MCO data collected since February 1996 up to September 2004 were examined and, at first, the night time data and the day time data (in winter and summer) were separated. Then, the wavelet analysis on the night and day time data was applied. The main result of the analysis was the appearance of a very clear anomaly during summer (July–August) 1998, at day time and at night time. The anomaly is a strong exaltation of the signal components with period in the 25–40 days range. Theoretical calculations of electric field strength were made and the only way to justify this anomaly seems to be the occurrence of an increase of the ground wave propagation mode of the radio signal. Such an increase could have been produced by an increase of the ground conductivity and by modifications of some parameter of the troposphere, mainly the refractive index. On 15 August 1998 a seismic sequence started with 17 earthquakes (M=2.2–4.6) on the Reatini mountains, a seismogenic zone located 30 km far from the AS receiver along the path MCO-AS. In this paper, the possibility that the previous radio anomaly can be a precursor of this seismic sequence is proposed.

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Possible earthquake precursors revealed by LF radio signals

Natural Hazards and Earth System Science ◽

10.5194/nhess-1-99-2001 ◽

2001 ◽

Vol 1 (1/2) ◽

pp. 99-104 ◽

Cited By ~ 16

Author(s):

P. F. Biagi ◽

R. Piccolo ◽

A. Ermini ◽

S. Martellucci ◽

C. Bellecci ◽

...

Keyword(s):

Field Strength ◽

Electric Field ◽

Electric Field Strength ◽

Ionospheric Disturbance ◽

Central Italy ◽

Low Noise ◽

Meteorological Conditions ◽

The Other ◽

Data Set ◽

Radio Signals

Abstract. Among radio signals, low frequency (LF) radio signals lie in the band between 30–300 kHz. Monitoring equipment with the ability to measure the electric strength of such signals at field sites, were designed and assembled in Italy. From 1993 onwards, the electric field strength of the MCO (216 kHz, France) broadcasting station has been collecting measurements at two sites in central Italy that were chosen according to very low noise levels. At the end of 1996, radio signals from the CLT (189 kHz, Italy) and CZE (270 kHz, Czech Republic) broadcasting stations were included in the measurements. Meteorological data from central Italy were also collected over the same time period in order to study the influence of weather conditions on the experimental measurements. During the monitoring period, we observed some evident attenuation of the electric field strength in some of the radio signals at some of the receivers. The duration of the attenuation observed was several days, so it could possibly be related to particular meteorological conditions. On the other hand, this phenomenon might represent precursors of moderate (3.0 < M < 3.5) earthquakes that occurred near the receivers (within 50 km) along the transmitter-receiver path. In this case, it is possible that the pre-seismic processes could have produced irregularities in the troposphere, such as ducts, reflecting layers and scattering zones, so that some local troposphere defocusing of the radio signals might have occurred. These observations were related only to moderate earthquakes and in these cases, suitable meteorological conditions were probably needed to observe the effect. Between February – March 1998, we observed at one measuring site, a significant increase in the CZE electric field strength. Unfortunately, we could not use the data of the other receiver in this case, due to frequent interruptions in the data set. The increase might have been a precursor of the strong seismic sequence (M = 5.0–6.0) that occurred during March – May 1998 in Slovenia at a location over 400 km from the receiver, but lying in the middle of the transmitter-receiver path. In this case, it is possible that an ionospheric disturbance, produced by the pre-seismic processes, might have occurred.

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Optical Measurement of the Electric Field Strength in a Gel Insulator

IEEJ Transactions on Electronics Information and Systems ◽

10.1541/ieejeiss.136.1420 ◽

2016 ◽

Vol 136 (10) ◽

pp. 1420-1421

Author(s):

Yusuke Tanaka ◽

Yuji Nagaoka ◽

Hyeon-Gu Jeon ◽

Masaharu Fujii ◽

Haruo Ihori

Keyword(s):

Field Strength ◽

Electric Field ◽

Electric Field Strength ◽

Optical Measurement

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Effect of external magnetic field on lane formation in driven pair-ion plasmas

Journal of Plasma Physics ◽

10.1017/s0022377821000027 ◽

2021 ◽

Vol 87 (2) ◽

Author(s):

Swati Baruah ◽

U. Sarma ◽

R. Ganesh

Keyword(s):

Magnetic Field ◽

External Magnetic Field ◽

Field Strength ◽

Electric Field ◽

Electric Field Strength ◽

Coupling Parameter ◽

Critical Parameters ◽

Coulomb Coupling ◽

Lane Formation ◽

Parameter Values

Lane formation dynamics in externally driven pair-ion plasma (PIP) particles is studied in the presence of external magnetic field using Langevin dynamics (LD) simulation. The phase diagram obtained distinguishing the no-lane and lane states is systematically determined from a study of various Coulomb coupling parameter values. A peculiar lane formation-disintegration parameter space is identified; lane formation area extended to a wide range of Coulomb coupling parameter values is observed before disappearing to a mixed phase. The different phases are identified by calculating the order parameter. This and the critical parameters are calculated directly from LD simulation. The critical electric field strength value above which the lanes are formed distinctly is obtained, and it is observed that in the presence of the external magnetic field, the PIP system requires a higher value of the electric field strength to enter into the lane formation state than that in the absence of the magnetic field. We further find out the critical value of electric field frequency beyond which the system exhibits a transition back to the disordered state and this critical frequency is found as an increasing function of the electric field strength in the presence of an external magnetic field. The movement of the lanes is also observed in a direction perpendicular to that of the applied electric and magnetic field directions, which reveals the existence of the electric field drift in the system under study. We also use an oblique force field as the external driving force, both in the presence and absence of the external magnetic field. The application of this oblique force changes the orientation of the lane structures for different applied oblique angle values.

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Overscreening, Co-Ion-Dominated Electroosmosis, and Electric Field Strength Mediated Flow Reversal in Polyelectrolyte Brush Functionalized Nanochannels

ACS Nano ◽

10.1021/acsnano.0c09248 ◽

2021 ◽

Author(s):

Turash Haque Pial ◽

Harnoor Singh Sachar ◽

Parth Rakesh Desai ◽

Siddhartha Das

Keyword(s):

Field Strength ◽

Electric Field ◽

Electric Field Strength ◽

Flow Reversal ◽

Polyelectrolyte Brush

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Sensor of the electric field strength vector components in the form of three mutually perpendicular square

Journal of Physics Conference Series ◽

10.1088/1742-6596/1791/1/012038 ◽

2021 ◽

Vol 1791 (1) ◽

pp. 012038

Author(s):

S V Biryukov ◽

S S Kolmogorova ◽

A S Kolmogorov

Keyword(s):

Field Strength ◽

Electric Field ◽

Electric Field Strength ◽

Strength Vector

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Investigating the feasibility of cerebellar transcranial direct current stimulation to facilitate post-stroke overground gait performance in chronic stroke: a partial least-squares regression approach

Journal of NeuroEngineering and Rehabilitation ◽

10.1186/s12984-021-00817-3 ◽

2021 ◽

Vol 18 (1) ◽

Author(s):

Dhaval Solanki ◽

Zeynab Rezaee ◽

Anirban Dutta ◽

Uttama Lahiri

Keyword(s):

Field Strength ◽

Electric Field ◽

Electric Field Strength ◽

Chronic Stroke ◽

Least Squares Regression ◽

Significance Level ◽

Gait Performance ◽

Wilcoxon Rank Sum Test ◽

Gait Parameters ◽

The Mean

Abstract Background Investigation of lobule-specific electric field effects of cerebellar transcranial direct current stimulation (ctDCS) on overground gait performance has not been performed, so this study aimed to investigate the feasibility of two lobule-specific bilateral ctDCS montages to facilitate overground walking in chronic stroke. Methods Ten chronic post-stroke male subjects participated in this repeated-measure single-blind crossover study, where we evaluated the single-session effects of two bilateral ctDCS montages that applied 2 mA via 3.14 cm2 disc electrodes for 15 min targeting (a) dentate nuclei (also, anterior and posterior lobes), and (b) lower-limb representations (lobules VIIb-IX). A two-sided Wilcoxon rank-sum test was performed at a 5% significance level on the percent normalized change measures in the overground gait performance. Partial least squares regression (PLSR) analysis was performed on the quantitative gait parameters as response variables to the mean lobular electric field strength as the predictors. Clinical assessments were performed with the Ten-Meter walk test (TMWT), Timed Up & Go (TUG), and the Berg Balance Scale based on minimal clinically important differences (MCID). Results The ctDCS montage specific effect was found significant using a two-sided Wilcoxon rank-sum test at a 5% significance level for 'Step Time Affected Leg' (p = 0.0257) and '%Stance Time Unaffected Leg' (p = 0.0376). The changes in the quantitative gait parameters were found to be correlated to the mean electric field strength in the lobules based on PLSR analysis (R2 statistic = 0.6574). Here, the mean electric field strength at the cerebellar lobules, Vermis VIIIb, Ipsi-lesional IX, Vermis IX, Ipsi-lesional X, had the most loading and were positively related to the 'Step Time Affected Leg' and '%Stance Time Unaffected Leg,' and negatively related to the '%Swing Time Unaffected Leg,' '%Single Support Time Affected Leg.' Clinical assessments found similar improvement in the TMWT (MCID: 0.10 m/s), TUG (MCID: 8 s), and BBS score (MCID: 12.5 points) for both the ctDCS montages. Conclusion Our feasibility study found an association between the lobular mean electric field strength and the changes in the quantitative gait parameters following a single ctDCS session in chronic stroke. Both the ctDCS montages improved the clinical outcome measures that should be investigated with a larger sample size for clinical validation. Trial registration: Being retrospectively registered.

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