Ultra low frequeney electromagnetic wave anomaly and its spectrum characteristics before earthquakes

Many observations and researches show that abundant and intense ultra low frequency (ULF) electromagneticanomalies appears before local earthquakes. In order to understand this phenomenon systematically, the trans-mission property and the formation of the seismic-electric dipole are discussed in this paper. The results showthat the vertical component Of the ULF electric anomaly before earthquake has the properties of better penetration, less disturbance and high signal-to-noise ratio. The signal can be easily extracted and received. The anomaly should be an important way to seek for reliable short-term and imminent earthquake precursors. After thespectrum analysis of the (ULF) electric field anomalies, we found that the periods of the anomaly related to localearthquakes are from a few minutes to a dozens minutes. There is a relation between the spectrum of the anomaly and the epicentral distance. The ULF electric field anomalies strongly rely on the orientation of the seismo-genie zone. The percolation electric field anomaly and its spectrum amplitude do not have obvious relation withthe size of local earthquakes.

Research on the Characteristics of Anomalies in ELF Electromagnetic Observations in Yunnan Province

Located in an earthquake-prone region,the geological structures in Yunnan Province are complex. Taking into account that Tonghai county is located in the intersection of Xiaojiang fault and Honghe fault, an ACF-4M ELF electromagnetic instrument was installed at the Tonghai seismic station,which has produced continuous reliable data. The author collected the data and information for the year 2009 and 2010,and performed analysis on the variation characteristics of both geomagnetic fields and electrical resistivity. The result shows that the 1Hz and 39Hz electromagnetic power spectra are 0. 2 to 1. 4 orders of magnitude higher than the normal values immediately before many earthquakes. The anomalies are represented by the abrupt changes of the electric and magnetic field power spectra in earthquake and aftershock sequences,and the amplitude of change is related to the size of earthquake magnitude and epicentral distance. The electrical resistivity also obviously changes. Therefore, further research on the anomalous characteristics of ELF electromagnetic data will be meaningful to the future use of this instrument in earthquake prediction.

Atom-based power-frequency electric field measurement using the radio-frequency-modulated Rydberg spectroscopy

The radio-frequency modulated electromagnetically induced transparency(EIT) in a ladder three-level system with Rydberg state is studied. Under the influence of a fast radio-frequency field, the EIT peak splits into a series of sidebands.When attaching a power-frequency electric field directly to the fast radio-frequency field, the odd-order sidebands of the Rydberg-EIT oscillate sensitively with the power-frequency field. The oscillation frequency is equal to twice the power frequency;the oscillation amplitude is monotonically increasing with the amplitude of the power-frequency field when the change of Stark-shift is smaller than the radio frequency. Our work paves the way for measurement of power-frequency electric field based on Rydberg atoms.

Study on Emitted Radiations from Filament Bulb of Different Power

The research work is carried out to find spectrum of wavelength of the emitted radiations from filament bulb. Both temperature and wavelength measurement are based on theoretical model. The temperature finding formula for tungsten filament is obtained by using blackbody radiation approach. The peak wavelength of the emitted radiation is obtained 1.461 μm and 1.125 μm for 6 and 500 watt bulb respectively by using Wein’s displacement law which depends upon temperature of the filament. The wavelength obtained by using Wein’s displacement law, is just an index, which helps to investigate, “how the radiation energy density is distributed” so as to give rise to an electromagnetic spectrum. The results obtained from the applied methodologies show that the accuracy of a model is quite good. Some mathematical techniques and probability theory are used to verify the work. The work is followed by both classical and quantum analysis to justify the results. Temperature only is not the key factor that deserves power of the bulb. The value of resistance plays a vital role in fixing power of the bulb. At least one factor is important in the calibration of the power of the bulb, “either temperature or surface area” of the filament.

Factors affecting the spectrum of an electromagnetic light wave on scattering from a semisoft boundary medium

The spectrum of an electromagnetic light wave on scattering from a semisoft boundary medium is discussed within the accuracy of the first-order Born approximation. It is shown that spectral shifts and spectral switches are affected both by the polarization of the incident light wave and by the characters of the scat-tering medium. Moreover, numerical results show that the direction at which the spectral switch occurs is governed by the characters of the scattering medium, whereas the magnitude of the spectral switch is affected by the polarization of the incident light wave.