Anomalous Seismo-Electromagnetic Emission Related with Seismic Waves
This paper reports the rare high intensity electromagnetic pulses associated with earthquakes, with different to atmospherics spectrum signature. On the base of actual data records, the cases of generation of anomalous seismo-electromagnetic emission founded. These natural sub-millisecond electromagnetic pulses have been associated with passage of seismic waves through the place of electromagnetic field observations. The waveform, spectrum and time characteristics of sub-millisecond electromagnetic pulses have been described. The deeper the source the lower frequencies can be observed in the spectrum on the surface.
Modeling and analyzing of seismo-electromagnetics disturbance on crust of earth using FDTD method
In this paper, finite-difference time-domain (FDTD) method is applied for modeling and analyzing seismo-electromagnetics disturbance on the crust of earth. The proposed method is developed by modeling geographical map of the frontier between Sumatra island and Java island in 3D object based on a cylindrical coordinate system. To truncate the object simulation, uniaxial perfectly matched layer (UPML) boundary conditions are implemented. The amplitude variation of observed very low frequency (VLF) wave and propagation time between the disturbance and observation point are discussed. The result shows that the addition pulse influences the amplitude of observed sinusoidal VLF wave instead of its frequency. The propagation time of disturbance pulse is also influenced by the distance and the permittivity of the propagation medium.
Navigation&#8212;An overview
While there are some 250 000 civil aircraft in the world, only about 500 of them are in transoceanic service and therefore prime candidates for the systems described in this special issue. The rest mainly depend on short-range systems treated elsewhere. However, there are 25 000 ocean-going merchant ships. The article discusses some nontechnical factors that influence the choice of systems for these markets, including the institutional, the "CNI" factor, the marketplace, cost, redundancy, and vulnerability.