Electromagnetic Field Variations Research Articles

Technical Research for Oil Well Variable Frequency Electromagnetic Field Paraffin Prevention

Oil well paraffin is one problem that often occurs in oil production; it will seriously affect or even suspend production. There are many kinds of paraffin prevention technologies, but limited to particular conditions or other factors, there are still shortcomings and insufficiency of all these technologies. In order to make this process environmental, efficient and energy saving, we propose the technique of variable frequency electromagnetic field paraffin. According to the principle of Maxwell's electromagnetic theory, the reciprocal transformation of electromagnetic field and magnetic field intensity are determined by diameter of coil, current intensity, as well as the turn number of coils. The optimal parameter for paraffin prevention is defined by the selection of the current intensity and frequency of the conversion electromagnetic field in the laboratory so as to achieve optimum efficiency of paraffin prevention. Judging from the practice in three wells in site, this technology can extend flushing period, increase oil production, reduce power consumption and improve efficiency of oil well production, so the application of this technology has a very broad and bright prospect.

Square Electrode Representation in FDTD Method

An algorithm is proposed for finite-difference time-domain (FDTD) method simulating of square electrode. To derive the electromagnetic field variation near the electrode, an electrostatically charged square electrode is involved and the field is decoupled into 4 parts. Each part can be derived from the integral of the differential electric field which is radiated by the distributed charge on one surface of the square electrode. The accuracy of the proposed representation algorithm has been approved from comparison with high-resolution standard FDTD simulation results.

Stabilization of electromagnetic solitons in thin films of topological insulators by constant electric field

We consider the propagation of a variable electromagnetic field in a thin film of a topological insulator in low temperatures case at the presence of electric field. As a result we obtain an effective equation on the vector-potential amplitude of a variable electromagnetic field. We also detect some solutions, corresponding to solitons in the case of a cosine-type dispersion law for electronic subsystem. Finally, we analysed how non-linear solutions depend on the parameters of the problem and on electrostatic field.

Contribution of the source velocity to the scattering of electromagnetic fields caused by airborne magnetic dipoles

The velocity of controlled airborne sources of electromagnetic geophysical surveys plays an additional role in the scattering of the fields by the earth. Therefore, it is necessary to investigate its contribution in the space and time variation of secondary electromagnetic fields. The model of a vertical magnetic dipole moving at a constant speed along a horizontal line in the air and above a homogeneous conductive half-space constitutes a first approach to stress the kinematic aspect and determine the difference between the fields due to an airborne and a static source. The magnetic moment of the source is equal to 104 A m2, its height is 120 m, and the horizontal and vertical separations between it and the receiver are, respectively, equal to 100 and 50 m: these values of the model are typical of towed-bird airborne TDEM surveys. We employed four values for the common velocities of source and receiver (0, 60, 80, and 100 m s−1), four values of the conductivity of the half-space (0.5, 0.1, 0.05, and 0.01 S m−1), and two causal source currents (box with periods of 80 and 10 ms and periodic with frequency values of 12.5 and 100 Hz). The results demonstrate that the relative velocity between source and medium yields a measurable variation compared to the static condition. Therefore, it must be taken into consideration by compensating the discrepancy in measured data employing the respective theoretical result. The results also show that it is necessary to adjust the concepts of time and frequency domain for electromagnetic measurements with traveling sources.

Observations of kinetic scale field line resonances

AbstractWe identify electromagnetic field variations from the Van Allen Probes which have the properties of Doppler shifted kinetic scale Alfvénic field line resonances. These variations are observed during injections of energetic plasmas into the inner magnetosphere. These waves have scale sizes perpendicular to the magnetic field which are determined to be of the order of an ion gyro‐radius (ρi) and less. Cross‐spectral analysis of the electric and magnetic fields reveals phase transitions at frequencies correlated with enhancements and depressions in the ratio of the electric and magnetic fields. Modeling shows that these observations are consistent with the excitation of field‐line resonances over a broad range of wave numbers perpendicular to the magnetic field (k⊥) extending to k⊥ρi ≫ 1. The amplitude of these waves is such that E/Bo ≳ Ωi/k⊥ (E, Bo, and Ωi are the wave amplitude, background field strength, and ion gyro‐frequency, respectively) leading to ion demagnetization and acceleration for multiple transitions through the wave potential.

Application of Electromagnetic Field in Maize to Improve Productivity under Rain-fed Conditions

In order to know the feasibility of using physical methods such as pre-sowing treatment and evaluated infield for maize production in agrosystems with moisture and inputs limitations, five varieties were used: “HS-2”, “CP-20”, “Promesa”, “HT-Precoz”, “CPV-20”, and “Criollo de Mineral de Pozos”, Gto. The seeds were treated with 560 mT variable electromagnetic field during 30 minutes before sowing. There were significant statistical differences among treatments for ear weight and for varieties in plant height and ear height and weight. The HS-2 hybrid had the lowest value for emergency velocity and emerged plants percentage, but yielded at 12% humidity 4,950 t ha -1

An Algorithm for the FDTD Modeling of Flat Electrodes in Grounding Systems

A sub-cell algorithm for the finite-difference time-domain (FDTD) modeling of flat electrode in grounding systems is proposed. The electromagnetic field variation near a flat electrode is derived from the integral of the differential electric field which is radiated by the distributed charge on an electrostatic charged flat electrode. By fully incasing the field singularity into the coarse cells containing the electrode with the Faraday's Law, a sub-cell algorithm has been proposed to reduce computational resources when modeling the flat electrode. The accuracy of the derived field singularity is verified from comparison with the field given by the high-resolution standard FDTD simulation. The efficiency of the proposed algorithm has been approved by verifying the transient grounding resistance (TGR) of the grounding system using the proposed algorithm and the computational memory and time usage.

Two‐dimensional simulations of the tsunami dynamo effect using the finite element method

Conductive seawater moving in the geomagnetic main field generates electromotive force in the ocean. This effect is well known as the “oceanic dynamo effect.” Recently, it has been reported that tsunamis are also associated with the oceanic dynamo effect, and tsunami‐induced electromagnetic field variations were actually observed on the seafloor. For instance, our research group succeeded in observing tsunami‐induced magnetic variations on the seafloor in the northwest Pacific at the time of the 2011 Tohoku earthquake. In this study, we developed a time domain tsunami dynamo simulation code using the finite element method to explain the tsunami‐induced electromagnetic variations observed on the seafloor. Our simulations successfully reproduced the observed seafloor magnetic variations as large as 3 nT. It was also revealed that an initial rise in the horizontal magnetic component prior to the tsunami arrival as large as 1 nT was induced by the tsunami.

Behavioral Responses of Representative Freshwater Fish Species to Electromagnetic Fields

AbstractHydrokinetic energy is proposed as an environmentally preferred means of generating electricity from river and tidal currents. To resolve environmental concerns, it is important to investigate potential effects on aquatic organisms from the electromagnetic fields (EMFs) that are created by underwater generators and transmission cables. We evaluated the behavioral responses of some representative freshwater fishes to static and variable EMFs in a series of laboratory experiments. Fish were exposed for 46 h to a static (DC) EMF with a permanent bar magnet or to a variable (AC) EMF with an electromagnet. Fish locations were recorded with a digital imaging system, and changes in activity level and distribution relative to the magnet position were quantified at 5‐min intervals. Experiments with Fathead Minnow Pimephales promelas, Redear Sunfish Lepomis microlophus, Striped Bass Morone saxatilis, Lake Sturgeon Acipenser fulvescens, and Channel Catfish Ictalurus punctatus produced mixed results. Except for Fathead Minnow, there was no effect on fish activity level. Only Redear Sunfish and Channel Catfish exhibited a change in distribution relative to the position of the magnet, with both species showing an apparent attraction to the EMF source. In a separate experiment, rapid behavioral responses of Paddlefish Polyodon spathula and Lake Sturgeon to the onset of an AC field were recorded with high‐speed video. Paddlefish did not react to a variable, 60‐Hz magnetic field (i.e., like that emitted by an AC generator or cable), but Lake Sturgeon consistently responded with a variety of altered swimming behaviors. These results will be useful for positioning cables or generators to minimize interactions with EMF‐sensitive species.

Energy-2M generating-measuring complex of directional operation for seismic monitoring and sounding of ore objects

A generating-measuring complex of directional operation, which allows investigating seismically dangerous zone of stressedly-deformed state of rock, ore zones, and fracture zones in the directions which are the most sensitive from the standpoint of the aim in view, namely along and across the strike axes of the object of interest, is developed. The complex includes the Energy-2M directional operation generator and a portable high-sensitivity KVVN-7m measuring station that allows performing frequency probing with controllable sources and sounding in the field of natural electromagnetic field variations during one cycle. The generator includes a system of independent phase and amplitude adjustment of the current at the output of the Energy-2M generator inverter along two channels. A circuit of programmed generator current supply to two mutually orthogonal antenna arrays (long grounded lines) and a system of precision control over the current parameters in each arm is developed. The generator allows generating a programmed current with circular or elliptical field polarization in the vicinity of the object under study in the specified direction in the frequency range from 1 to 2000 Hz. The Energy-2M generator is mounted on board a ZIL-131 motor vehicle and fed by two PN-72 generators 15 kW each. The KVVN-7 digital measuring station has been completely modified. Moreover, all out-of-date elements have been replaced by modern operational amplifiers characterized by extremely low internal noises, which do not exceed unities or tenths of nV/Hz0.5. The generating complex is equipped with a system for control, regulation, protection, and automation (SCRPA) based on GPS time synchronization. Thermostatting of the unit for clock frequency and reference voltage is provided. All these measures allowed reaching the accuracy of synchronization over the absolute time not worse than 2 × 10−4 s, and frequency stability of the generator signal not worse than 10−7 Hz.

Magnetotelluric Response Function Estimation Based on Hilbert–Huang Transform

Magnetotelluric (MT) data series are non-stationary random signals that do not meet the basic requirements of conventional methods based on the Fourier transform. To minimize the estimation bias errors brought about by the non-stationary characteristics of MT data, a new method, based on the Hilbert–Huang transform (HHT), is proposed for the first time for estimating the MT response functions from a time series of electromagnetic field variations. With the HHT method, the amplitude of data series are expressed as a function of frequency and time and then response functions are estimated statistically from the time–frequency spectrum. Mathematical model and calculation processes are introduced and some simulated data are analyzed to verify the correctness of the method. Finally, the measured MT data is facilitated by applying the HHT to assess the ability of HHT method to quantify meaningful geologic information.

Scaling law describes Earth's electromagnetic environment

The electromagnetic environment surrounding Earth, including the geomagnetic field and atmospheric electric fields, varies on all time scales, but this frequency dependence has not been well studied. Analyzing observations compiled from several published sources,Füllekrug and Fraser‐Smith found that the energy density of the electromagnetic fields at the surface of the Earth follows a simple, fundamental scaling law: The energy density of the fields at a given frequency is inversely proportional to the square of the frequency. This relationship extends over a wide range of frequencies—16 orders of magnitude. The authors note that this is somewhat surprising, given the many different processes that cause electromagnetic field variations, including lightning discharge in the atmosphere, geomagnetic storms in the ionosphere, and many other electromagnetic effects, such as sprites in the middle atmosphere.

Reply to comment on ‘Using cold atoms to measure neutrino mass’

We discuss questions raised concerning the proposal of kinematically reconstructing the neutrino mass using an ultracold source of tritium atoms (Otten E W 2011 New J. Phys.13 078001). We provide further details about our two-dimensional fit and emphasize the importance of simultaneously utilizing information from both the neutrino mass squared peak and the β-spectrum. We also explain how the simulation evolved over various drafts of the paper, and we comment on future directions for additional simulation work, including more detailed simulations of spectrometers and electromagnetic field variations.

ESDガンの垂直結合板への間接放電で生ずる空間電磁界のばらつき

ESDガンの垂直結合板への間接放電で生ずる空間電磁界のばらつき

The stabilization of magnetic solitons in carbon nanotubes by a constant electric field at low temperatures

The propagation of a variable electromagnetic field in a bundle of zigzag carbon nanotubes in the presence of a constant electric field at low temperatures is considered. The electronic system of nanotubes is treated microscopically ignoring interactions with the phonon subsystem, because the electromagnetic field pulse is extremely short. An effective equation for the amplitude of the vector-potential of a variable electromagnetic field was obtained. Solutions similar to solitons that corresponded to isolated waves in the case of the cosine dispersion law for the electronic subsystem were revealed. The dependences of the obtained nonlinear solutions on problem parameters and an applied constant electric field were analyzed.

Studies of the electromagnetic field variations in ELF frequency range registered by DEMETER over the Sichuan region prior to the 12 May 2008 earthquake

Analysis of the low frequency fluctuations of the magnetic and electric fields prior to a strong earthquake of magnitude 8.0 on 12 May 2008 in Sichuan Province is given. We analyse the disturbances of the ionospheric electromagnetic field prior to the earthquake starting 2 weeks before this event, but detailed analysis is given for 6 and 9 May, 6 and 3 days prior to the earthquake, when the observed effects were strongest. Special attention is given to the characteristics of the spectra of these variations and the search for nonlinear effects. This analysis is possible in the time intervals when the extra low frequency (ELF) waveform was transmitted. Although the mechanism of energy transmission from the earthquake preparation zone to the ionosphere is not determined, it can be said that the ionospheric plasma is an unstable medium and that even a small perturbation can lead to variations in the electromagnetic field and plasma parameters. Some attempts at this discussion are given in the paper. The observations by Detection of Electro-Magnetic Emissions Transmitted from Earthquake Regions (DEMETER) and discussed in this paper suggest the presence of plasma turbulence over the area above the Wenchuan Earthquake on 12 May 2008. The characteristics of the observed disturbances are studied with wavelet and bispectral analysis, tools which are more relevant for analysing plasma turbulence.

Plasma turbulence in the ionosphere prior to earthquakes, some remarks on the DEMETER registrations

The question about presence of some precursors of the earthquakes has a long history. The answer is still not resolved, but researchers are looking for the effects which can be registered prior to earthquakes. One of the factors which has been found is the variation of the electromagnetic field observed on ground as well as onboard satellites. The disturbances of the electromagnetic field around areas of the earthquakes as pre-seismic events can occur few hours or even few days before the main shock. The payload of the DEMETER French microsatellite allows to measure waves and also some important plasma parameters (ion composition, electron density and temperature, energetic particles) with high temporal resolution in the ionosphere over the seismic regions. In the present work, analysis of the low frequency fluctuations of the electric fields for selected strong earthquakes in Japan (2004), China (2008), Taiwan (2006) and New Zealand (2009) are given. Special attention will be given to the study of the spectral characteristics of these variations and the search for nonlinear effects. This analysis is possible in the time interval where the waveform has been transmitted. The mechanism of the energy transmission from earthquakes to the ionosphere is not clear, but we can discuss the behavior of the ionospheric plasma and the search for instabilities which could be a source of electromagnetic field variations. A brief discussion of the characteristics of the spectra and multi-spectra is given in this paper. Attention is particularly given to the effect prior to the earthquake in New Zealand, when a nonlinear interaction leading to a lower hybrid wave generation was directly seen.

Electromagnetic solitons in carbon nanotubes at low temperatures

The propagation of a variable electromagnetic field in arrays of “zigzag” carbon nanotubes at low temperatures is considered. The electronic system of carbon nanotubes is analyzed using the Hamilton formalism with ignoring interactions with the phonon subsystem because the electromagnetic field pulse is extremely short. An effective equation for the amplitude of the electromagnetic field vector-potential was obtained. Solutions-analogues of solitons were revealed; these solutions corresponded to solitons for the cosine electronic subsystem dispersion law. The dependences of the nonlinear solutions obtained on problem parameters were analyzed.

Variations in geoacoustic emissions in a deep borehole and its correlation with seismicity

Continuous geoacoustic emission (GAE) measurements were acquired using a three-component geophone placed in a borehole at a depth of near 1000 m at Petropavlovsk-Kamchatsky starting in August 2000. Using geophones consisting of magneto-elastic crystal ferromagnetic sensors, and installed at such a depth allows measurement of natural geoacoustic background with signal amplitude less than 1×10 -4 m/s 3 in frequency band from 3 to 1500 Hz. According to the data from a 4-year survey period the characteristics of diurnal geoacoustic variations change before every earthquake with MLH≥ 5.0 that occurs at a distance of less than 300 km from the observation point or before each earthquake with MLH≥5.5 occurring at distance R≤550 km from the observation point. The changes in GAE regime correlate with the strongest earthquakes that occurred during survey period. Measurements of the natural electromagnetic field of the Earth were carried out simultaneously with the help of an underground electric antenna. The behavior of GAE in aseismic periods appears to be related to the effect of diurnal variations of the natural electromagnetic field.

Variations of global thunderstorm activity from observations of the first Schumann resonance intensity in the Arctic

On the basis of variations of the atmospheric noise electromagnetic field at the frequency of the first Schumann resonance (SR-1), as measured during 2007 in the central part of the Kola Peninsula, it is shown that the changes in SR-1 power reflect the main known space-time features of the global lightning activity. During 2007, the energetic relationships changed significantly between the power maxima of SR-1, caused by the effects of the African, Asian, and American thunderstorm centers. In February, practically full absence is observed of the African power maximum of SR-1. A clearly pronounced maximum of the SR-1 power is revealed near 6:00 UTC, whose the most probable source can be thunderstorm zone in the central Pacific with a maximum of activity within the range of 21:00–22:00 local time; the power of this zone being several times lower than that of three main world thunderstorm centers.