scholarly journals Ionospheric influence on the seismo-telluric current related to electromagnetic signals observed before the Wenchuan <i>M</i><sub><i>S</i></sub> 8.0 earthquake

Solid Earth ◽  
2016 ◽  
Vol 7 (5) ◽  
pp. 1405-1415 ◽  
Author(s):  
Mei Li ◽  
Handong Tan ◽  
Meng Cao
Keyword(s):  
Power Distribution ◽  
Current Source ◽  
Electric Signal ◽  
Ionospheric Effect ◽  
Electrical Fields ◽  
Ionospheric Effects ◽  
Model Free ◽  
Ionosphere Model ◽  
The Earth ◽  
Electromagnetic Signals

Abstract. A three-layer (Earth–air–ionosphere) physical model, as well as a two-layer (Earth–air) model, is employed in this paper to investigate the ionospheric effect on the wave fields for a finite length dipole current source co-located at a hypocenter depth and along the main fault of an earthquake when the distance between the epicenter and an observing station is up to 1000 km or even more. The results show that all electrical fields are free of ionospheric effects for different frequencies in a relative short range, e.g.,  ∼  300 km for f =  1 Hz, implying the ionospheric influence on electromagnetic fields can be neglected within this range, which becomes smaller as the frequency increases. However, the ionosphere can give a constructive interference to the waves passing through and make them decay slowly when an observation is out of this range; moreover, the ionospheric effect can be up to 1–2 orders of magnitude of the electrical fields. For a ground-based observable 1.3 mV m−1 electric signal at f =  1 Hz 1440 km away from the Wenchuan MS 8.0 earthquake, the expected seismo-telluric current magnitude for the Earth–air–ionosphere model is of 5.0  ×  107A, 1 magnitude smaller than the current value of 3.7  ×  108A obtained by the Earth–air model free of ionospheric effects. This indicates that the ionosphere facilitates the electromagnetic wave propagation, as if the detectability of the system were improved effectively and it is easier to record a signal even for stations located at distances beyond their detectability thresholds. Furthermore, the radiating patterns of the electrical field components |Ex| and |Ey| are complementary to each other, although any two-dimensional (2-D) power distribution of these components shows strong power areas as well as weak ones, which is advantageous to register a signal if the observing system is designed to measure both of them instead of only one.

scholarly journals Ionospheric influence on the seismo-telluric current related to electromagnetic signals observed before the Wenchuan <i>M</i><sub>S</sub> = 8.0 earthquake

2016 ◽  
Author(s):  
Mei Li ◽  
Handong Tan ◽  
Meng Cao
Keyword(s):  
Current Source ◽  
Ionospheric Effect ◽  
Electrical Fields ◽  
Model Free ◽  
Ionosphere Model ◽  
The Earth ◽  
Main Fault ◽  
Electromagnetic Signals ◽  
The Waves ◽  
Detectability Threshold

Abstract. A three-layer (Earth-air-ionosphere) physical model, as well as a two-layer (Earth-air) model, is employed in this paper to investigate the ionospheric effect on the wave fields for a finite length dipole current source co-located with the main fault of an earthquake when the transmitter-receiver distance is up to one thousand kilometers or even more. The results show that all electrical fields are free of the ionospheric effect for different frequencies in a relative short range, e.g., ~ 300 km for f = 1 Hz, implying the ionospheric influence on electromagnetic fields can be neglected within this range that becomes smaller as the frequency increases. However, the ionosphere can give a constructive interference to the waves passed through and make them decay slowly when an observation is out of this range and the ionosperic effect can be up to 1–2 magnitudes of the electrical fields. For an observed 1.3 mV/m signal at 1,440 km away for the Wenchuan MS = 8.0 earthquake, the expected seismo-telluric current magnitude for the Earth-air-ionosphere model is of 5.0 × 104 kA , which is of one magnitude smaller than the current value of 3.7 × 105 kA obtained by the Earth-air model free of ionospheric effect. This indicates that the ionosphere facilitates the electromagnetic wave propagation, as if the detectability of the system is improved effectively and it is easier to record a signal even for stations located at distances beyond their detectability threshold.

scholarly journals Study of Geo-Electric Data Collected by the Joint EMSEV-Bishkek RS-RAS Cooperation: Possible Earthquake Precursors

Entropy ◽  
2018 ◽  
Vol 20 (8) ◽  
pp. 614
Author(s):  
Konstantina Papadopoulou ◽  
Efthimios Skordas ◽  
Jacques Zlotnicki ◽  
Toshiyasu Nagao ◽  
Anatoly Rybin
Keyword(s):  
Epicentral Distance ◽  
Current Source ◽  
Earthquake Precursors ◽  
The Other ◽  
Electric Signal ◽  
Seismic Events ◽  
The Earth ◽  
Subsurface Resistivity ◽  
Telluric Currents ◽  
Electric Current Source

By employing the cross-correlogram method, in geo-electric data from the area of Kyrgyzstan for the period 30 June 2014–10 June 2015, we identified Anomalous Telluric Currents (ATC). From a total of 32 ATC after taking into consideration the electric current source properties, we found that three of them are possible Seismic Electric Signal (SES) activities. These three SES activities are likely to be linked with three local seismic events. Finally, by studying the corresponding recordings when a DC alternating source injects current into the Earth, we found that the subsurface resistivity seems to be reduced before one of these three earthquakes, but a similar analysis for the other two cannot be done due to their large epicentral distance and the lack of data.

scholarly journals Study of Power Flow in an IPT System Based on Poynting Vector Analysis

Energies ◽  
2018 ◽  
Vol 11 (1) ◽  
pp. 165 ◽  
Author(s):  
Yuan Liu ◽  
Aiguo Hu
Keyword(s):  
Output Power ◽  
Power Distribution ◽  
Power Flow ◽  
Poynting Vector ◽  
Current Source ◽  
Arbitrary Point ◽  
Secondary Coil ◽  
Surface Integral ◽  
Vector Method ◽  
Coupled Coils

This paper analyzes the power distribution and flow of an inductive power transfer (IPT) system with two coupled coils by using the Poynting vector. The system is modelled with a current source flowing through the primary coil, and a uniformly loaded secondary first, then the Poynting vector at an arbitrary point is analyzed by calculating the magnetic and electric fields between and around of the two coils. Both analytical analysis and numerical analysis have been undertaken to show the power distribution, and it has found that power distributes as a donut shape in three-dimensional (3D) space and concentrates along the edges in the proposed two-coil setup, instead of locating coaxially along the center path. Furthermore, power flow across the mid-plane between the two coils is analyzed analytically by the surface integral of the Poynting vector, which is compared with the input power from the primary and the output power to the secondary coil via coupled circuit theory. It has shown that for a lossless IPT system, the power transferred across the mid-plane is equal to the input and output power, which validates the Poynting vector approach. The proposed Poynting vector method provides an effective way to analyze the power distribution in the medium between two coupled coils, which cannot be achieved by traditional lumped circuit theories.

scholarly journals Adoption of Multilevel Inverter based Dynamic Voltage Restorer for Power Quality Improvement with Adjustable DC-Link

2020 ◽  
Vol 184 ◽  
pp. 01055
Author(s):  
Kummari Geethika ◽  
Vinay Kumar Awaar ◽  
Praveen Jugge
Keyword(s):  
Power Distribution ◽  
Electrical Power ◽  
Current Source ◽  
Multilevel Inverter ◽  
Voltage Sag ◽  
Voltage Profile ◽  
Frequency Method ◽  
Dynamic Voltage Restorer ◽  
Voltage Restorer ◽  
Dynamic Voltage

Dynamic Voltage Restorer (DVR) is a method of overcoming voltage sag and swell in electrical power distribution. To boost up voltage levels on load side on power disturbances DVR can be used so as the equipment connected will have good voltage profile In this Pulse Width Modulation inverter is in solid-state electronic switching device were employed along with Integrated Gate Bipolar Transistor by the DVR, the alternating current voltage is controllable at real and reactive powers which are made independently. The MLI; is organized as the cascaded H-bridge inverter units. The function of Multilevel Inverter; is to arrange the voltages from a significant direct current source. Here in the DVR, there is no need for external output filters. In the planned DVR, a dc-dc converter is combined with an MLI. By considering the voltage sag magnitude of a dc-dc converter can regulate the dc-link voltage. Hence the output voltage of the multilevel inverter; always has a last number of levels. Instead of using the PWM based technique, the fundamental frequency method can be used in the multilevel inverter. The proposed DVR operation range of mathematical analysis is specified in detail. The simulation results are prepared by using Simulink/MATLAB.

Using spacecraft range data and radar observations for the improvement of the orbital elements of planets and parameters of Mars rotation

1996 ◽  
Vol 172 ◽  
pp. 45-48
Author(s):  
E.V. Pitjeva
Keyword(s):  
Major Axis ◽  
Astronomical Unit ◽  
Range Data ◽  
Orbital Elements ◽  
Semi Major Axis ◽  
The Earth ◽  
Electromagnetic Signals ◽  
Least Squares Estimates ◽  
Radar Ranging ◽  
Made In

The extremely precise Viking (1972–1982) and Mariner data (1971–1972) were processed simultaneously with the radar-ranging observations of Mars made in Goldstone, Haystack and Arecibo in 1971–1973 for the improvement of the orbital elements of Mars and Earth and parameters of Mars rotation. Reduction of measurements included relativistic corrections, effects of propagation of electromagnetic signals in the Earth troposphere and in the solar corona, corrections for topography of the Mars surface. The precision of the least squares estimates is rather high, for example formal standard deviations of semi-major axis of Mars and Earth and the Astronomical Unit were 1–2 m.

HIGH‐FREQUENCY ELECTROMAGNETIC COUPLING BETWEEN SMALL COPLANAR LOOPS OVER AN INHOMOGENEOUS GROUND

Geophysics ◽  
1972 ◽  
Vol 37 (6) ◽  
pp. 997-1004 ◽  
Author(s):  
James A. Fuller ◽  
James R. Wait
Keyword(s):  
Half Space ◽  
High Frequency ◽  
Electromagnetic Coupling ◽  
Current Source ◽  
Vertical Axis ◽  
Loop Current ◽  
Mutual Impedance ◽  
Multiplicative Factor ◽  
The Earth ◽  
Horizontal Electric Dipole

An integral formulation is given for the fields of a loop current source which is located over a horizontally stratified half‐space and has a vertical axis. The electrical properties of the half‐space vary exponentially with the depth into the earth. An asymptotic solution is developed for the case of source and observer on the interface but separated by a large numerical distance. The approximate solution is then used to determine the mutual impedance between two small loops and between the loop and a horizontal electric dipole, when the antennas are on the interface. It is found that the effect of stratification on the mutual impedance is represented approximately by a single multiplicative factor.

On the Ensemble Transfer Entropy Analysis of Non-Stationary Geophysical Time Series: The Case of Magnetospheric Response

2020 ◽  
Author(s):  
Mirko Stumpo ◽  
Giuseppe Consolini ◽  
Tommaso Alberti ◽  
Virgilio Quattrociocchi
Keyword(s):  
Time Series ◽  
Fundamental Question ◽  
Entropy Analysis ◽  
Crucial Point ◽  
Information Theoretic ◽  
Model Free ◽  
Statistical Framework ◽  
The Earth ◽  
Geophysical Time Series ◽  
Dynamical Coupling

&lt;p&gt;The fundamental question what causes what has always been the motivating motto for natural sciences, being the study of causality a crucial point for characterizing dynamical relationships. In the framework of complex dynamical systems, both linear statistical tools and Granger causality models drastically fail to detect causal relationships between time series, while a powerful model-free statistical framework is offered by the information theory.&amp;#160;&lt;/p&gt;&lt;p&gt;Here we discuss how to deal with the problem of measuring causal information in non-stationary complex systems by considering a local estimation of the information-theoretic functionals via an ensemble-based statistics. Then, its application for investigating the dynamical coupling and relationships between the solar wind and the Earth&amp;#8217;s magnetosphere is also presented.&amp;#160;&lt;/p&gt;

Artificial Insulating Joints for Stray Current Mitigative Measurements★

CORROSION ◽  
1957 ◽  
Vol 13 (10) ◽  
pp. 18-20
Author(s):  
G. H. CANTWELL
Keyword(s):  
Direct Current ◽  
Carrying Capacity ◽  
Current Source ◽  
Electrical Measurements ◽  
Stray Current ◽  
The Earth

Abstract In making electrical measurements pertinent to determining stray current mitigative measures, it is often desirable to determine the effect of a proposed insulating joint at a predetermined location. By applying a direct current source between the structure and the earth in the manner described in this paper, simulation of an insulating joint is achieved. Since the method is entirely electrical, the placing of temporary insulating joints for test purposes is eliminated. This method can be applied to any structure carrying stray DC earth currents. In addition to simulating an insulating joint, the associated current and potential measurements are used to determine (1) the resistance to earth of the structure on each side of the point of application, (2) the potential to earth that would exist on each side of a permanent insulating joint, (3) the potential across the permanent insulating joint. They also provide data for determining the resistance and current carrying capacity for a bridging resistor. 4.5.3

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