Microstructural evolution and strengthening mechanism of aligned steel fiber cement-based tail backfills exposed to electromagnetic induction

Cemented tailings backfill(CTB)not only boosts mining safety and cuts surface environmental pollution but also recovers ores previously retained as pillars,thereby improving resource utilization.The use of alternative reinforcing products,such as steel fiber(SF),has continuously strengthened CTB into SFCTB.This approach prevents strength decreases over time and reinforces its long-term durability,especially when mining ore in adjacent underground stopes.In this study,various microstructure and strength tests were performed on SFCTB,considering steel fiber ratio and electromagnetic induction strength effects.Lab findings show that combining steel fibers and their distribution dominantly influences the improvement of the fill’s strength.Fill’s strength rises by fiber insertion and has an evident correlation with fiber insertion and magnetic induction strength.When magnetic induction strength is 3×10^(-4) T,peak uniaxial compressive stress reaches 5.73 MPa for a fiber ratio of 2.0vol%.The cracks’expansion mainly started from the specimen’s upper part,which steadily expanded downward by increasing the load until damage occurred.The doping of steel fiber and its directional distribution delayed crack development.When the doping of steel fiber was 2.0vol%,SFCTBs showed excellent ductility characteristics.The energy required for fills to reach destruction increases when steel-fiber insertion and magnetic induction strength increase.This study provides notional references for steel fibers as underground filling additives to enhance the fill’s durability in the course of mining operations.

Spatio-Temporal Changes of Soil Salinity in Arid Areas of South Xinjiang Using Electromagnetic Induction

The aim of this paper was to research the spatio-temporal changes in total soluble salt content （TS） in a typical arid region of South Xinjiang, China, where the climate is arid and soil salinization happens easily. The total soluble salt content was interpreted by measurements made in the horizontal mode with EM38 and EM31. The electromagnetic induction （EM） surveys were made three times with the apparent soil electrical conductivity （ECa） measurements taken at 3 873 locations in Nov. 2008, 4 807 locations in Apr. 2009 and 6 324 locations in Nov. 2009, respectively. For interpreting the ECa measurements into total soluble salt content, calibtion sites were needed for EM survey of each time, e.g., 66 sites were selected in Nov. 2008 to measure ECa, and soils-core samples were taken by different depth layers of 0-10, 10-20 and 20-40 cm at the same time. On every time duplicate samples were taken at five sites to allevaite the local-scale variability, and soil temperatures in different layers through the profiles were also measured. Factors including TS, pH, water content, bulk density were analyzed by lab experiments. ECa calibration equations were obtained by linear regression analysis, which indicated that soil salinity was one primary concern to ECa with a determination coefficient of 0.792 in 0-10 cm layer, 0.711 in 10-20 cm layer and 0.544 in 20-40 cm layer, respectively. The maps of spatial distribution were predicted by Kriging interpolation, which showed that the high soil salinity was located near the drainage canal, which validated the trend effect caused by the irrigation canal and the drainage canal. And by comparing the soil salinity in different layers, the soluble salt accumulated to the top soil surface only in the area where the soil salinization was serious, and in the other areas, the soil salinity trended to increase from the top soil surface to 40 cm depth. Temporal changes showed that the soil salinity in November was higher than that in April, and the soil salinization trended to aggravate, especially in the top soil layer of 0-10 cm.

Thermoelectric Energy Conversion of a Drinking Bird by Disk-Magnet Electromagnetic Induction

We discuss a thermoelectric energy generation (TEG) technique by employing a thermomechanical model of a drinking bird (DB). The motion of a drinking bird is produced by the entropy-flow explained by the second law of thermodynamics, which is one of the fundamental laws of heat engines. We propose a disk-magnet electromagnetic induction (DM-EMI) employed to the motion of a drinking bird. The generalization of DM-EMI to heat engines for?mechanoelectric?energy conversions and properties of extracted electric powers are specifically discussed. The electric power of DM-EMI has a limited power generation characteristic to a mechanical rotation produced by heat engines, but it will be very useful for practical applications to wind turbines, coal-fired and nuclear power plant for?mechanoelectric?energy conversions. The DM-EMI will contribute to environmental problems to maintain clean and susceptible energy as one of?energy?harvesting technologies.

An analytic electromagnetic calculation method for performance evolution of doubly fed induction generators for wind turbines

An analytic electromagnetic calculation method for doubly fed induction generator(DFIG) in wind turbine system was presented. Based on the operation principles, steady state equivalent circuit and basic equations of DFIG, the modeling for electromagnetic calculation of DFIG was proposed. The electromagnetic calculation of DFIG was divided into three steps: the magnetic flux calculation, parameters derivation and performance checks. For each step, the detailed numeric calculation formulas were all derived. Combining the calculation formulas, the whole electromagnetic calculation procedure was established, which consisted of three iterative calculation loops, including magnetic saturation coefficient, electromotive force and total output power. All of the electromagnetic and performance data of DIFG can be calculated conveniently by the established calculation procedure, which can be used to evaluate the new designed machine. A 1.5 MW DFIG designed by the proposed procedure was built, for which the whole type tests including no-load test, load test and temperature rising test were carried out. The test results have shown that the DFIG satisfies technical requirements and the test data fit well with the calculation results which prove the correctness of the presented calculation method.

Stochastic resonance and synchronization behaviors of excitatory-inhibitory small-world network subjected to electromagnetic induction

The phenomenon of stochastic resonance and synchronization on some complex neuronal networks have been investigated extensively.These studies are of great significance for us to understand the weak signal detection and information transmission in neural systems.Moreover,the complex electrical activities of a cell can induce time-varying electromagnetic fields,of which the internal fluctuation can change collective electrical activities of neuronal networks.However,in the past there have been a few corresponding research papers on the influence of the electromagnetic induction among neurons on the collective dynamics of the complex system.Therefore,modeling each node by imposing electromagnetic radiation on the networks and investigating stochastic resonance in a hybrid network can extend the interest of the work to the understanding of these network dynamics.In this paper,we construct a small-world network consisting of excitatory neurons and inhibitory neurons,in which the effect of electromagnetic induction that is considered by using magnetic flow and the modulation of magnetic flow on membrane potential is described by using memristor coupling.According to our proposed network model,we investigate the effect of induced electric field generated by magnetic stimulation on the transition of bursting phase synchronization of neuronal system under electromagnetic radiation.It is shown that the intensity and frequency of the electric field can induce the transition of the network bursting phase synchronization.Moreover,we also analyze the effect of magnetic flow on the detection of weak signals and stochastic resonance by introducing a subthreshold pacemaker into a single cell of the network and we find that there is an optimal electromagnetic radiation intensity,where the phenomenon of stochastic resonance occurs and the degree of response to the weak signal is maximized.Simulation results show that the extension of the subthreshold pacemaker in the network also depends greatly on coupling strength.The presented results may have important implications for the theoretical study of magnetic stimulation technology,thus promoting further development of transcranial magnetic stimulation（TMS） as an effective means of treating certain neurological diseases.

Mathematical Multibody Model of a Soft Mounted Induction Motor Regarding Forced Vibrations Due to Dynamic Rotor Eccentricities Considering Electromagnetic Field Damping

The paper presents a mathematical multibody model of a soft mounted induction motor with sleeve bearings regarding forced vibrations caused by dynamic rotor eccentricities considering electromagnetic field damping. The multibody model contains the mass of the stator, rotor, shaft journals and bearing housings, the electromagnetic forces with respect of electromagnetic field damping, stiffness and internal (rotating) damping of the rotor, different kinds of dynamic rotor eccentricity, stiffness and damping of the bearing housings and end shields, stiffness and damping of the oil film of the sleeve bearings and stiffness and damping of the foundation. With this multibody model, the bearing housing vibrations and the relative shaft vibrations in the sleeve bearings can be derived.

Electromagnetic characteristics of cold crucible in an induction coil for melting purpose

The electromagnetic characteristics of cold wall crucible, especially its field strength and distribution, were evaluated experimentally, in which the effects of parameters as input power and position were also discussed. The results showed that the magnetic induction intensity （B） increased with the increase of the input power. Along the radial direction inside the cold crucible, B is the strongest at the edges, and gradually attenu- ated from the edges to the center. While along the axial direction, B is the strongest at the center, and gradually attenuated from the center to the edges. Corresponding with the calculation on electromagnetic field distribution inside the coil without cold crucible, the effects of cold crucible on the electromagnetic field have been reduced by comparing measured and calculated results. However, it was also found that the value of B strength will be decreased to about 50% of its original proposition without cold crucible due to the electromagnetic shielding effect, which will be the understanding for mehing turns in cold crucible.

Assessment and application of electromagnetic induction method to measure Arctic sea ice thickness

The electromagnetic induction method is widely used to measure sea ice thickness. Based on the electrical properties of sea ice and seawater, the method measures the apparent conductivity, which represents the conductivity of the half-space, and calculates the thickness of the sea ice. During the fourth Chinese National Arctic Research Expedition in summer 2010, an integrated electromagnetic induction system was set up on the icebreaker R/V XUE LONG to measure sea ice thickness along the ship＇s tracks to the north of the Chukchi Sea. The conductivities of sea ice, seawater, and brine were measured and a simple forward model was used to explain the effect of changes in those conductivities on the apparent conductivity over a horizontal layered structure. The results of this analysis indicated that when using the electromagnetic induction method to measure sea ice thickness, the conductivity of sea ice could be neglected and the conductivity of seawater could be treated as a constant. The ice distribution results derived from the electromagnetic induction method showed that the typical sea ice thickness was 160 cm and 90 cm during the outbound and the return legs of the voyage, respectively.

Magnetic Oil Thermal Behavior under Electromagnetic Induction for Energy Efficient Heating System Design

This study describes thermal behavior of magnetic lubricant oil under electromagnetic induction. Experimental set up include oil pump, oil tank, induction heating unit, and heat exchanger. It is a closed loop system where the oil pump circulates oil through oil tank to the system, at the same time induction heating unit heats up to the heat exchanger where the lubricant oil thermal behavior is examined. The unit has been largely studied and tested both magnetic and regular motor oil in a laboratory environment and promising results have been obtained for an actual indoor floor to space heating system design.

Fhe application of electromagnetic-induction on the measurement of sea ice thickness in the Antarctic

As an important component of the cryosphere, sea ice is very sensitive to climate change. The study of sea ice physics needs accurate sea ice thickness. This paper presents an electromagnetic induction （EM） technique which can be used to measure the sea ice thickness distribution efficiently and its successful application in the Antarctic Neila Fjord. Based on the electrical properties of sea ice and seawater and the application of electromagnetic field theory, this technique can accurately detect the distance between the EM instrument and the ice/water interface to measure the sea ice thickness. Analyzing the apparent conductivity data obtained by the electromagnetic induction technique and drill-hole measurements at same location allows the construction of a transform equation for the apparent conductivity and sea ice thickness. The verification of the calculated sea ice thickness using this equation indicates that the electromagnetic induction technique is able to determine reliable sea ice thickness with an average relative error of only 5.5%. The ice thickness profiles show the sea ice distribution in Neila Fjord is basically level with a thickness of 0.8 - 1.4 m.

Magnetic and Electric Charges in Physics and Technology of Electromagnetic and Magnetoelectric Induction

Experimental and theoretical researches performed by the author (period: 1969-present) showed that magnetic spinor particles (magnetic charges) are real structural components of atoms and substance and immediate sources of all magnetic fields and magnetic manifestations in Nature. Magnetic charges, that constitute together with electrical charges atomic shells got of title: magnetons and antimagnetons (respectively with charges g−and g+ under fundamental condition: g = e). Furthermore, in addition to participating in structures of atomic shells, the magnetic charges exist in potential and even in real zones conduction of solids. The magnetic and electric spinor particles in atoms and substance exist in form such of the spinor associations as the magnetic and electric bispinors. Under influence of external magnetic field in conductor being implemented polarization of magnetic bispinors with formation of magnetic dipoles. Internal fields magnetic dipoles is directed against an external magnetic field and is a simple explanation of such a physical manifestation as diamagnetism. During the rotation of these dipoles in the conductor are formed of the vortex magnetic dipole fields, which and create an electromotive force, i.e. are responsible for the electromagnetic induction. Author proposed new magneto-electric technology called the magnetoelectric induction, as the result of which the permanent current of magnetic charges is created. However, such currents may be implemented solely in the superconductors. In the article presented the main reasons which more hundred year old hinder recognition and technical use of the real magnetic charges and their currents what considerably slow down the global scientific and technological progress.

A finite volume method for global electromagnetic induction forward modeling on collocated unstructured grids

Global electromagnetic induction provides an efficient way to probe the electrical conductivity in the Earth’s deep interior.Owing to the increasing geomagnetic data especially from high-accuracy geomagnetic satellites,inverting the Earth’s three-dimensional conductivity distribution on a global scale becomes attainable.A key requirement in the global conductivity inversion is to have a forward solver with high-accuracy and efficiency.In this study,a finite volume method for global electromagnetic induction forward modeling is developed based on unstructured grids.Arbitrary polyhedral grids are supported in our algorithms to obtain high geometric adaptability.We employ a cell-centered collocated variable arrangement which allows convenient discretization for complex geometries and straightforward implementation of multigrid technique.To validate the method,we test our code with two synthetic models and compare our finite volume results with an analytical solution and a finite element numerical solution.Good agreements are observed between our solution and other results,indicating acceptable accuracy of the proposed method.

Quantitative Evaluation and Uncertainty Assessment on Geostatistical Simulation of Soil Salinity Using Electromagnetic Induction Technique

Diagnosis of soil salinity and characterizing its spatial variability both vertically and horizontally are needed to establish control measures in irrigated agriculture. In this regard, it is essential that salinity development in varying soil depths be known temporally and spatially. Apparent soil electrical conductivity, measured by electromagnetic induction instruments, has been widely used as an auxiliary variable to estimate spatial distribution of field soil salinity. The main objectives of this paper were adopted a mobile electromagnetic induction (EMI) system to perform field electromagnetic (EM) survey in different soil layers, to evaluate the uncertainty through Inverse Distance Weighted (IDW) and Ordinary Kriging (OK) methods, and to determine which algorithm is more reliable for the local and spatial uncertainty assessment. Results showed that EM38 data from apparent soil electrical conductivity are highly correlated with salinity, more accurate for estimating salinity from multiple linear regression models, which the correlation coefficient of 0 - 20, 20 - 40, 40 - 60 and 60 - 80 cm were 0.9090, 0.9228, 0.896 and 0.9085 respectively. The comparison showed that the prediction accuracy of two methods also displays good performance for soil salinity, the estimation precision of IDW method (with E = 0.8873, 0.9075, 0.8483 and 0.901, RPD = 9.64, 8.01, 8.17 and 11.23 in 0 - 20, 20 - 40. 40 - 60 and 60 - 80 cm soil layers, respectively) was superior to that of OK (with E = 0.8857, 0.872, 0.8744 and 0.8822, RPD = 9.44, 7.83, 8.52 and 10.88, respectively), but differences of two methods in predictions are not significant. The obtained salinity map was helpful to display the spatial patterns of soil salinity and monitor and evaluate the management of salinity.

The Disk-Magnet Electromagnetic Induction Applied to Thermoelectric Energy Conversions

The thermoelectric energy conversion technique by employing the Disk-Magnet Electromagnetic Induction (DM-EMI) and improved DM-EMIs is shown, and possible applications to heat engines as one of the energy harvesting technologies are also discussed. The idea is induced by integrating irreversible thermodynamical mechanism of a water drinking bird with that of a Stirling engine, resulting in thermoelectric energy generation different from conventional heat engines. The current thermoelectric energy conversion with DM-EMI can be applied to wide ranges of temperature differences. The mechanism of DM-EMI energy converter is examined in terms of axial flux magnetic lines and categorized as the axial flux generator. It is useful for practical applications to macroscopic heat engines such as wind, geothermal, thermal and nuclear power turbines and heat-dissipation lines, for supporting thermoelectric energy conversions. The technique of DM-EMI will contribute to environmental problems to maintain clean and susceptible energy as one of the energy harvesting technologies.

Dynamical response of a neuron–astrocyte coupling system under electromagnetic induction and external stimulation

Previous studies have observed that electromagnetic induction can seriously affect the electrophysiological activity of the nervous system. Considering the role of astrocytes in regulating neural firing, we studied a simple neuron–astrocyte coupled system under electromagnetic induction in response to different types of external stimulation. Both the duration and intensity of the external stimulus can induce different modes of electrical activity in this system, and thus the neuronal firing patterns can be subtly controlled. When the external stimulation ceases, the neuron will continue to fire for a long time and then reset to its resting state. In this study, "delay" is defined as the delayed time from the firing state to the resting state, and it is highly sensitive to changes in the duration or intensity of the external stimulus. Meanwhile, the self-similarity embodied in the aforementioned sensitivity can be quantified by fractal dimension. Moreover, a hysteresis loop of calcium activity in the astrocyte is observed in the specific interval of the external stimulus when the stimulus duration is extended to infinity, since astrocytic calcium or neuron electrical activity in the resting state or during periodic oscillation depends on the initial state. Finally, the regulating effect of electromagnetic induction in this system is considered. It is clarified that the occurrence of "delay" depends purely on the existence of electromagnetic induction. This model can reveal the dynamic characteristics of the neuron–astrocyte coupling system with magnetic induction under external stimulation. These results can provide some insights into the effects of electromagnetic induction and stimulation on neuronal activity.

Sea ice thickness measurement in spring season in Bothnian Bay using an electromagnetic induction instrument

As an important component of the cryosphere,sea ice is very sensitive to the climate change.The study of the sea ice physics needs accurate sea ice thickness.This paper presents an electromagnetic-induction(EM) technique which can be used to measure the sea ice thickness distribution efficiently,and the successful application in Bothnian Bay.Based on the electromagnetic field theory and the electrical properties of sea ice and seawater,EM technique can detect the distance between the instrument and the ice/water interface accurately,than the sea ice thickness is obtained.Contrastive analysis of the apparent conductivity data obtained by EM and the value of drill-hole at same positions allows a construction of a transformable formula of the apparent conductivity to sea ice thickness.The verification of the sea ice thickness calculated by this formula indicates that EM technique is able to get reliable sea ice thickness with average relative error of only 12%.The statistic of all ice thickness profiles shows that the level ice distribution in Bothnian Bay was 0.4-0.6 m.

Crustal and Upper Mantle Research in Pannonian Basin by Electromagnetic Induction:A Review

The review paper summarizes the main results of the electromagnetic induction studies carried out in the Pannonian Basin and Carpathians during the last 30 years . The following conducting formations are discussed in detail : (1)Crustal conductors in the crystalline basement of the sedimentary basin mainly due to graphitic schist blocks clearly connected to the fracture tectonics of the area ; (2 ) Conducting layer in the lower crust probably due to free fluid deliberated by the dehydration process at temperature of 300-400℃during metamorphism ; (3 ) Conducting asthenosphere due to partial melting at the bottom of the lithosphere ; and (4) Conductivity increases due to olivine-spinel phase transition .All of these phenomena are strongly related to the special thermal state and tectonics of the Pannonian Basin and Carpathians.

Improvement of the Structure and the Electromagnetic Characteristics of an Induction Ladle Furnace

Based on a numerical analysis of the alternating electromagnetic field in the process of Steel refining with an induction ladle furnace (ILF), the optimization of the structure of ILF and the electromagnetic field for melting is realized in the present work. The optimization of the ILF by outward extension of inner yokes can decrease the magnitic flux leakage obviously, reduce the eddy current energy loss dramatically and then, decrease the total power consumption.

Detection of Graphene Cracks By Electromagnetic Induction,Insensitive to Doping Level

Detection of cracks is a great concern in production and operation processes of graphene based devices to ensure uniform quality.Here,we show a detection method for graphene cracks by electromagnetic induction.The time varying magnetic field leads to induced voltage signals on graphene,and the signals are detected by a voltmeter.The measured level of induced voltage is correlated with the number of cracks in graphene positively.The correlation is attributed to the increasing inductive characteristic of defective graphene,and it is verified by electromagnetic simulation and radio frequency analysis.Furthermore,we demonstrate that the induced voltage signal is insensitive to the doping level of graphene.Our work can potentially lead to the development of a high-throughput and reliable crack inspection technique for mass production of graphene applications.

CHOPPING WAVE METHOD FOR REMOVING ELECTROMAGNETIC INDUCTION COUPLING

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