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Sample records for electromagnetic induction tomography

  1. Electromagnetic forward and inverse problems of non-rotating magnetoacoustic tomography with magnetic induction.

    PubMed

    Zhang, Yang; Liu, Guoqiang; Tao, Chunjing; Wang, Hao; He, Wenjing

    2009-01-01

    The analysis of electromagnetic forward and inverse problems is very important in the process of image reconstruction for magnetoacoustic tomography with magnetic induction (MAT-MI). A new analysis method was introduced in this paper. It breaks through some illogical supposes that the existing methods applied and can improve the spatial resolution of the image availably. Besides it can avoid rotating the static magnetic field which is very difficult to come true in application, therefore the development of MAT-MI technique can be promoted greatly. To test the validity of the new method, two test models were analyzed, and the availability of the method was demonstrated.

  2. Electromagnetic induction methods

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Electromagnetic induction geophysical methods are finding greater and greater use for agricultural purposes. Electromagnetic induction methods measure the electrical conductivity (or resistivity) for a bulk volume of soil directly beneath the surface. An instrument called a ground conductivity meter...

  3. A finite-difference frequency-domain code for electromagnetic induction tomography

    SciTech Connect

    Sharpe, R M; Berryman, J G; Buettner, H M; Champagne, N J.,II; Grant, J B

    1998-12-17

    We are developing a new 3D code for application to electromagnetic induction tomography and applications to environmental imaging problems. We have used the finite-difference frequency- domain formulation of Beilenhoff et al. (1992) and the anisotropic PML (perfectly matched layer) approach (Berenger, 1994) to specify boundary conditions following Wu et al. (1997). PML deals with the fact that the computations must be done in a finite domain even though the real problem is effectively of infinite extent. The resulting formulas for the forward solver reduce to a problem of the form Ax = y, where A is a non-Hermitian matrix with real values off the diagonal and complex values along its diagonal. The matrix A may be either symmetric or nonsymmetric depending on details of the boundary conditions chosen (i.e., the particular PML used in the application). The basic equation must be solved for the vector x (which represents field quantities such as electric and magnetic fields) with the vector y determined by the boundary conditions and transmitter location. Of the many forward solvers that could be used for this system, relatively few have been thoroughly tested for the type of matrix encountered in our problem. Our studies of the stability characteristics of the Bi-CG algorithm raised questions about its reliability and uniform accuracy for this application. We have found the stability characteristics of Bi-CGSTAB [an alternative developed by van der Vorst (1992) for such problems] to be entirely adequate for our application, whereas the standard Bi-CG was quite inadequate. We have also done extensive validation of our code using semianalytical results as well as other codes. The new code is written in Fortran and is designed to be easily parallelized, but we have not yet tested this feature of the code. An adjoint method is being developed for solving the inverse problem for conductivity imaging (for mapping underground plumes), and this approach, when ready, will

  4. Use of electromagnetic induction tomography for monitoring liquid metal/gas flow regimes on a model of an industrial steel caster

    NASA Astrophysics Data System (ADS)

    Terzija, N.; Yin, W.; Gerbeth, G.; Stefani, F.; Timmel, K.; Wondrak, T.; Peyton, A. J.

    2011-01-01

    Monitoring of the steel flow through the submerged entry nozzle (SEN) during continuous casting presents a challenge for the instrumentation system because of the high temperature environment and the limited access to the nozzle in between the tundish and the mould. Electromagnetic inductance tomography (EMT) presents an attractive tool to visualize the steel flow profile within the SEN. In this paper, we investigate various flow regimes over a range of stopper positions and gas volume flow rates on a model of a submerged entry nozzle. A scaled (approximately 10:1) experimental rig consisting of a tundish, stopper rod, nozzle and mould was used. Argon gas was injected through the centre of the stopper rod and the behaviour of the two-phase GaInSn/argon flow was studied. The experiments were performed with GaInSn as an analogue for liquid steel, because it has similar conductive properties as molten steel and allows measurements at room temperature. The electromagnetic system used in our experiments to monitor the behaviour of the two-phase GaInSn/argon flow consisted of an array of eight equally spaced induction coils arranged around the object, a data acquisition system and a host computer. The present system operates with a sinusoidal excitation waveform with a frequency of 40 kHz and the system has a capture rate of 40 frames per second. The results show the ability of the system to distinguish the different flow regimes and to detect the individual bubbles. Sample tomographic images given in the paper clearly illustrate the different flow regimes.

  5. Electromagnetic Induction Rediscovered Using Original Texts.

    ERIC Educational Resources Information Center

    Barth, Michael

    2000-01-01

    Describes a teaching unit on electromagnetic induction using historic texts. Uses some of Faraday's diary entries from 1831 to introduce the phenomenon of electromagnetic induction and teach about the properties of electricity, of taking conclusions from experiment, and scientific methodology. (ASK)

  6. Electromagnetic Induction and Electrical Resistivity Tomography Applied to evaluate contamination at a site of disposal of animal wastes from a feedlot

    NASA Astrophysics Data System (ADS)

    Sainato, C. M.; Marquez Molina, J.; Losinno, B.; Urricariet, A. S.

    2012-12-01

    In Argentina, the systems of animal feeding in pens (feedlots) are expanding the production, generating a great quantity of solids and liquid residuals, being a highly risky source of soil and groundwater contamination. The aim of this work was to evaluate the relation between soil bulk conductivity and the distribution of concentrations of nitrates and other potential contaminants of groundwater from animal manure. Shallow electromagnetic induction (EMI) and electrical resistivity tomography (ERT) surveys were carried out at a pen of a feedlot at San Pedro , Bs. As. Province , Argentina, where large quantities of manure (3.5 m height) had been placed at the center of them, for a few months of activity. Soil sampling up to 2 m depth was performed for physical and chemical analysis. Wells were drilled for monitoring groundwater level (12 m depth) and water quality. Soil texture was defined as loamy clayey silty. Distribution of electrical conductivity obtained from the two exploration methods was similar, being higher the values at the pen than at the background site, coinciding with laboratory measurements of electrical conductivity of the saturation paste extract. At the center of the pen, bellow the manure accumulation, the highest values of conductivity were found (greater than 120mS/m), decreasing to the surroundings. However, values of N-NO3 in soil were lower at the center of the pen than at the surroundings. Concentration decreases with depth at sites of the pen with high soil compaction. Water content showed a strong influence on values of conductivity. Groundwater values of NO3 concentration do not exceed the level for human consumption although SO4 concentration increases respect to background deeper well.Values of conductivity and N-NO3 were still lower compared with the ones found at another pen with 10 years of use. An EMI survey carried out two years later showed an increase of twice the values of electrical conductivity. We conclude that higher

  7. University Students' Understanding of Electromagnetic Induction

    ERIC Educational Resources Information Center

    Guisasola, Jenaro; Almudi, Jose M.; Zuza, Kristina

    2013-01-01

    This study examined engineering and physical science students' understanding of the electromagnetic induction (EMI) phenomena. It is assumed that significant knowledge of the EMI theory is a basic prerequisite when students have to think about electromagnetic phenomena. To analyse students' conceptions, we have taken into account the fact that…

  8. Portable Electromagnetic Induction Sensor with Integrated Positioning

    DTIC Science & Technology

    2012-04-16

    Fridon Shubitidze, Juan Pablo Fernandez , and Kevin O’Neill. Simultaneous identification of multiple unexploded ordnance using electromagnetic induction...21] Juan Pablo Fernandez , Benjamin Barrowes, Alex Bijamov, Tomasz Grzegorczyk, Nicolas Lhomme, Kevin O’Neill, Irma Shamatava, and Fridon Shubitidze...unexploded ordnance. Geophysics, submitted for publication. 3 [3] Fridon Shubitidze, Ben Barrowes, Irma Shamatava, Juano Pablo Fernndez, and Kevin

  9. Electromagnetic induction in the moon

    NASA Technical Reports Server (NTRS)

    Sonett, C. P.

    1982-01-01

    The moon constitutes a nonhydromagnetic, but electrically conducting, target for the solar wind whose response reaches a peak as frequency increases and diminishes with further increase in frequency, suggesting the presence of the magnetic quadrupole moment. Magnetometer measurements of induction using Explorer and Apollo instruments are studied from both the harmonic and transient standpoint, and the resulting determination of internal bulk electrical conductivity is discussed. The closeness of the estimated internal temperature to the Ringwood-Essene solidus at 150-250 km depths suggests a layer of enhanced conductivity in lieu of high temperature. A reduced core radius estimate with a one-sigma upper limit of 360 km is reported. The discussion of lunar electrodynamics presented is restricted to the problem of induction, with only passing reference to flow fields and regional electric fields.

  10. Understanding Io's Interior Structure from Electromagnetic Induction

    NASA Astrophysics Data System (ADS)

    Khurana, K. K.; Keszthelyi, L. P.; Jia, X.

    2015-12-01

    Io has long been suspected of a molten interior based on theoretical models of tidal dissipation in its interior. Extremely high temperature lava erupting on Io's surface would be consistent with an internal magma ocean but the highest reported eruption temperatures are questionable. Currently, the only direct evidence of a subsurface magma ocean in Io is the electromagnetic induction response observed by Galileo (Khurana et al. 2011, Science, 332, 1186). Using Jupiter's rotating magnetic field as a sounding signal, Khurana et al. (2011) provided evidence of a strong dipolar induction signature in Galileo's magnetometer data from four different flybys. They further showed that the signal is consistent with electromagnetic induction from large amounts of rock-melts in the asthenosphere of Io. Modeling showed that the induction response from a completely solid mantle model is inadequate to explain the magnetometer observations. However, a layer of asthenosphere >50 km in thickness with a melt fraction ≥20% is adequate to accurately match the observed magnetic field. Here we summarize our current knowledge of Io's interior from Galileo's induction measurements, and then outline a scheme to further infer properties of Io's interior, especially its internal temperature profile, by marrying the principles of thermodynamics with those of electromagnetism. In particular, we obtain guidance on stable mineral phases and their physical properties (such as density, melt state and electrical conductivity) from thermodynamic principles, whereas guidance on how the resulting internal conductivity profile affects the magnetic environment around Io is obtained from electromagnetic theory. We also explore how induction measurements can be obtained at multiple frequencies from a future mission and be used to constrain both the location and the thickness of the magma ocean. Finally, we explore the consequences of the global magma ocean on Io's physical properties such as the current

  11. Electromagnetic Induction with Neodymium Magnets

    NASA Astrophysics Data System (ADS)

    Wood, Deborah; Sebranek, John

    2013-09-01

    In April 1820, Hans Christian Ørsted noticed that the needle of a nearby compass deflected briefly from magnetic north each time the electric current of the battery he was using for an unrelated experiment was turned on or off. Upon further investigation, he showed that an electric current flowing through a wire produces a magnetic field. In 1831 Michael Faraday and Joseph Henry separately expanded on Ørsted's discovery by showing that a changing magnetic field produces an electric current. Heinrich Lenz found in 1833 that an induced current has the opposite direction from the electromagnetic force that produced it. This paper describes an experiment that can help students to develop an understanding of Faraday's law and Lenz's law by studying the emf generated as a magnet drops through a set of coils having increasing numbers of turns.

  12. Electromagnetic induction holography imaging for stroke detection.

    PubMed

    Wang, Lulu

    2017-02-01

    This paper presents the application of the electromagnetic induction holography (EMIH) approach to imaging the electromagnetic activity of the brain, with a particular focus on stroke detection. An integral equation formulation is presented to describe the scattered magnetic field from the distribution of optically small dielectric and magnetic objects of arbitrary shapes adsorbed onto a planar electromagnetic substrate. A numerical computer model was developed in a MATLAB environment to validate the theory. Several realistic human head models were developed to investigate the detectability of strokes with the multi-channel EMIH system. Small strokes can be clearly identified with the correct location and size in the reconstructed head images. The simulation results demonstrated the feasibility of detecting and imaging small strokes using the approach.

  13. Science 101: What Causes Electromagnetic Induction?

    ERIC Educational Resources Information Center

    Robertson, Bill

    2013-01-01

    Electromagnetic induction is the technical name for the fact that, when a wire is moved near a magnet or a magnet is moved near a wire, an electric current flows in the wire. Although Bill Robertson honestly admits to not knowing why this happens, he does say that it is possible to get a deeper understanding of what's going on in terms of…

  14. A general law for electromagnetic induction

    NASA Astrophysics Data System (ADS)

    Giuliani, G.

    2008-03-01

    The definition of the induced emf as the integral over a closed loop of the Lorentz force acting on a unit positive charge leads immediately to a general law for electromagnetic induction phenomena. The general law is applied to three significant cases: moving bar, Faraday's and Corbino's disc. This last application illustrates the contribution of the drift velocity of the charges to the induced emf: the magneto-resistance effect is obtained without using microscopic models of electrical conduction. Maxwell wrote down "general equations of electromotive intensity" that, integrated over a closed loop, yield the general law for electromagnetic induction, if the velocity appearing in them is correctly interpreted. The flux of the magnetic field through an arbitrary surface that have the circuit as contour is not the cause of the induced emf. The flux rule must be considered as a calculation shortcut for predicting the value of the induced emf when the circuit is filiform. Finally, the general law of electromagnetic induction yields the induced emf in both reference frames of a system composed by a magnet and a circuit in relative uniform motion, as required by special relativity.

  15. Penetrating power of resonant electromagnetic induction imaging

    NASA Astrophysics Data System (ADS)

    Guilizzoni, Roberta; Watson, Joseph C.; Bartlett, Paul; Renzoni, Ferruccio

    2016-09-01

    The possibility of revealing the presence and identifying the nature of conductive targets is of central interest in many fields, including security, medicine, industry, archaeology and geophysics. In many applications, these targets are shielded by external materials and thus cannot be directly accessed. Hence, interrogation techniques are required that allow penetration through the shielding materials, in order for the target to be identified. Electromagnetic interrogation techniques represent a powerful solution to this challenge, as they enable penetration through conductive shields. In this work, we demonstrate the power of resonant electromagnetic induction imaging to penetrate through metallic shields (1.5-mm-thick) and image targets (having conductivities σ ranging from 0.54 to 59.77 MSm-1) concealed behind them.

  16. Electromagnetic Induction Survey of the Mississippi River in Cleveland, Mississippi

    DTIC Science & Technology

    2014-08-01

    Storm Damage Reduction Program under the Remote Sensing and Monitoring focus area. BACKGROUND: An electromagnetic (EM) induction survey was... Electromagnetic Induction Survey of the Mississippi River in Cleveland, Mississippi By Joseph B. Dunbar and Maureen K. Corcoran Report...REPORT TYPE 3. DATES COVERED 00-00-2014 to 00-00-2014 4. TITLE AND SUBTITLE Electromagnetic Induction Survey of the Mississippi River in Cleveland

  17. Imaging by electromagnetic induction with resonant circuits

    NASA Astrophysics Data System (ADS)

    Guilizzoni, Roberta; Watson, Joseph C.; Bartlett, Paul; Renzoni, Ferruccio

    2015-05-01

    A new electromagnetic induction imaging system is presented which is capable of imaging metallic samples of different conductivities. The system is based on a parallel LCR circuit made up of a cylindrical ferrite-cored coil and a capacitor bank. An AC current is applied to the coil, thus generating an AC magnetic field. This field is modified when a conductive sample is placed within the magnetic field, as a consequence of eddy current induction inside the sample. The electrical properties of the LCR circuit, including the coil inductance, are modified due to the presence of this metallic sample. Position-resolved measurements of these modifications should then allow imaging of conductive objects as well as enable their characterization. A proof-of-principle system is presented in this paper. Two imaging techniques based on Q-factor and resonant frequency measurements are presented. Both techniques produced conductivity maps of 14 metallic objects with different geometries and values of conductivity ranging from 0.54х106 to 59.77х106 S/m. Experimental results highlighted a higher sensitivity for the Q-factor technique compared to the resonant frequency one; the respective measurements were found to vary within the following ranges: ΔQ=[-11,-2]%, Δf=[-0.3,0.7]%. The analysis of the images, conducted using a Canny edge detection algorithm, demonstrated the suitability of the Q-factor technique for accurate edge detection of both magnetic and non-magnetic metallic samples.

  18. New cancellation technique for electromagnetic induction sensors

    NASA Astrophysics Data System (ADS)

    Scott, Waymond R., Jr.; Malluck, Michael

    2005-06-01

    A new technique is presented for canceling the coupling between the coils of an electromagnetic induction sensor while using simple dipole detection coils. A secondary bucking transformer is used to cancel the coupling between the coils. The technique allows the cancellation that can be obtained using a quadrupole receive coil while maintaining the depth sensitivity and simple detection zone of a dipole coil. Simple circuit models for the sensor with some of the important parasitic effects are developed. An experimental model is developed and used to demonstrate the technique. Experimental results are presented that demonstrate more than 75 dB of cancellation up to 100 kHz and the response of the sensor to a few targets.

  19. University Students' Understanding of Electromagnetic Induction

    NASA Astrophysics Data System (ADS)

    Guisasola, Jenaro; Almudi, Jose M.; Zuza, Kristina

    2013-11-01

    This study examined engineering and physical science students' understanding of the electromagnetic induction (EMI) phenomena. It is assumed that significant knowledge of the EMI theory is a basic prerequisite when students have to think about electromagnetic phenomena. To analyse students' conceptions, we have taken into account the fact that individuals build mental representations to help them understand how a physical system works. Individuals use these representations to explain reality, depending on the context and the contents involved. Therefore, we have designed a questionnaire with an emphasis on explanations and an interview, so as to analyse students' reasoning. We found that most of the students failed to distinguish between macroscopic levels described in terms of fields and microscopic levels described in terms of the actions of fields. It is concluded that although the questionnaire and interviews involved a limited range of phenomena, the identified explanations fall into three main categories that can provide information for curriculum development by identifying the strengths and weaknesses of students' conceptions.

  20. Fourier-based magnetic induction tomography for mapping resistivity

    SciTech Connect

    Puwal, Steffan; Roth, Bradley J.

    2011-01-01

    Magnetic induction tomography is used as an experimental tool for mapping the passive electromagnetic properties of conductors, with the potential for imaging biological tissues. Our numerical approach to solving the inverse problem is to obtain a Fourier expansion of the resistivity and the stream functions of the magnetic fields and eddy current density. Thus, we are able to solve the inverse problem of determining the resistivity from the applied and measured magnetic fields for a two-dimensional conducting plane. When we add noise to the measured magnetic field, we find the fidelity of the measured to the true resistivity is quite robust for increasing levels of noise and increasing distances of the applied and measured field coils from the conducting plane, when properly filtered. We conclude that Fourier methods provide a reliable alternative for solving the inverse problem.

  1. Fourier-based magnetic induction tomography for mapping resistivity

    PubMed Central

    Puwal, Steffan; Roth, Bradley J.

    2011-01-01

    Magnetic induction tomography is used as an experimental tool for mapping the passive electromagnetic properties of conductors, with the potential for imaging biological tissues. Our numerical approach to solving the inverse problem is to obtain a Fourier expansion of the resistivity and the stream functions of the magnetic fields and eddy current density. Thus, we are able to solve the inverse problem of determining the resistivity from the applied and measured magnetic fields for a two-dimensional conducting plane. When we add noise to the measured magnetic field, we find the fidelity of the measured to the true resistivity is quite robust for increasing levels of noise and increasing distances of the applied and measured field coils from the conducting plane, when properly filtered. We conclude that Fourier methods provide a reliable alternative for solving the inverse problem. PMID:21301637

  2. Some Student Conceptions of Electromagnetic Induction

    ERIC Educational Resources Information Center

    Thong, Wai Meng; Gunstone, Richard

    2008-01-01

    Introductory electromagnetism is a central part of undergraduate physics. Although there has been some research into student conceptions of electromagnetism, studies have been sparse and separated. This study sought to explore second year physics students' conceptions of electromagnetism, to investigate to what extent the results from the present…

  3. Electromagnetic Induction Aberration: The Possible Mechanism of Tic Douloureux

    PubMed Central

    2015-01-01

    A theory based on the principles of electromagnetic induction aberration is presented as the possible mechanism of classic trigeminal neuralgia, tic douloureux. The anatomy of the dorsal root entry zone of the trigeminal nerve at the pons in the proximity of the superior cerebellar artery presents a scenario conducive to the phenomenon of electromagnetic induction. When the action potentials traversing the axons in this zone of the compromised myelin come into juxtaposition with the vascular structure, the criteria for electromagnetic induction are satisfied. The laws of physics governing the phenomenon indicate that a new current, an aberration, would be produced. This could be responsible for the clinical symptoms of tic douloureux. Other clinical situations with similar features could share this mechanism. This proposed theory, a merger of anatomy, neurophysiology, and the physics of electromagnetic induction, extends the established concept of vascular compression as the etiology of tic douloureux. PMID:26180679

  4. Investigating Electromagnetic Induction through a Microcomputer-Based Laboratory.

    ERIC Educational Resources Information Center

    Trumper, Ricardo; Gelbman, Moshe

    2000-01-01

    Describes a microcomputer-based laboratory experiment designed for high school students that very accurately analyzes Faraday's law of electromagnetic induction, addressing each variable separately while the others are kept constant. (Author/CCM)

  5. Electromagnetic Induction Aberration: The Possible Mechanism of Tic Douloureux.

    PubMed

    Rish, Berkley

    2015-03-01

    A theory based on the principles of electromagnetic induction aberration is presented as the possible mechanism of classic trigeminal neuralgia, tic douloureux. The anatomy of the dorsal root entry zone of the trigeminal nerve at the pons in the proximity of the superior cerebellar artery presents a scenario conducive to the phenomenon of electromagnetic induction. When the action potentials traversing the axons in this zone of the compromised myelin come into juxtaposition with the vascular structure, the criteria for electromagnetic induction are satisfied. The laws of physics governing the phenomenon indicate that a new current, an aberration, would be produced. This could be responsible for the clinical symptoms of tic douloureux. Other clinical situations with similar features could share this mechanism. This proposed theory, a merger of anatomy, neurophysiology, and the physics of electromagnetic induction, extends the established concept of vascular compression as the etiology of tic douloureux.

  6. Model of electrical activity in cardiac tissue under electromagnetic induction.

    PubMed

    Wu, Fuqiang; Wang, Chunni; Xu, Ying; Ma, Jun

    2016-12-01

    Complex electrical activities in cardiac tissue can set up time-varying electromagnetic field. Magnetic flux is introduced into the Fitzhugh-Nagumo model to describe the effect of electromagnetic induction, and then memristor is used to realize the feedback of magnetic flux on the membrane potential in cardiac tissue. It is found that a spiral wave can be triggered and developed by setting specific initials in the media, that is to say, the media still support the survival of standing spiral waves under electromagnetic induction. Furthermore, electromagnetic radiation is considered on this model as external stimuli, it is found that spiral waves encounter breakup and turbulent electrical activities are observed, and it can give guidance to understand the occurrence of sudden heart disorder subjected to heavily electromagnetic radiation.

  7. Some Student Conceptions of Electromagnetic Induction

    NASA Astrophysics Data System (ADS)

    Thong, Wai Meng; Gunstone, Richard

    2008-01-01

    Introductory electromagnetism is a central part of undergraduate physics. Although there has been some research into student conceptions of electromagnetism, studies have been sparse and separated. This study sought to explore second year physics students’ conceptions of electromagnetism, to investigate to what extent the results from the present study are similar to these results from other studies, and to uncover any new forms of alternative conceptions. Data for this study came from 15 in-depth interviews. Three previously unreported alternative conceptions were identified in the study: 1) induced current varies proportionately with current in solenoid; 2) there must be contact between magnetic flux and the external coil in order for any emf to be induced in the coil; 3) coulombic or electrostatic potential difference is present in an induced electric field. These alternative conceptions were manifested in these students’ explanations of electromagnetic phenomena presented to them during the interviews.

  8. Advancements in Transmitters and Sensors for Biological Tissue Imaging in Magnetic Induction Tomography

    PubMed Central

    Zakaria, Zulkarnay; Rahim, Ruzairi Abdul; Mansor, Muhammad Saiful Badri; Yaacob, Sazali; Ayub, Nor Muzakkir Nor; Muji, Siti Zarina Mohd.; Rahiman, Mohd Hafiz Fazalul; Aman, Syed Mustafa Kamal Syed

    2012-01-01

    Magnetic Induction Tomography (MIT), which is also known as Electromagnetic Tomography (EMT) or Mutual Inductance Tomography, is among the imaging modalities of interest to many researchers around the world. This noninvasive modality applies an electromagnetic field and is sensitive to all three passive electromagnetic properties of a material that are conductivity, permittivity and permeability. MIT is categorized under the passive imaging family with an electrodeless technique through the use of excitation coils to induce an electromagnetic field in the material, which is then measured at the receiving side by sensors. The aim of this review is to discuss the challenges of the MIT technique and summarize the recent advancements in the transmitters and sensors, with a focus on applications in biological tissue imaging. It is hoped that this review will provide some valuable information on the MIT for those who have interest in this modality. The need of this knowledge may speed up the process of adopted of MIT as a medical imaging technology. PMID:22969341

  9. Advancements in transmitters and sensors for biological tissue imaging in magnetic induction tomography.

    PubMed

    Zakaria, Zulkarnay; Abdul Rahim, Ruzairi; Mansor, Muhammad Saiful Badri; Yaacob, Sazali; Ayub, Nor Muzakkir Nor; Muji, Siti Zarina Mohd; Rahiman, Mohd Hafiz Fazalul; Aman, Syed Mustafa Kamal Syed

    2012-01-01

    Magnetic Induction Tomography (MIT), which is also known as Electromagnetic Tomography (EMT) or Mutual Inductance Tomography, is among the imaging modalities of interest to many researchers around the world. This noninvasive modality applies an electromagnetic field and is sensitive to all three passive electromagnetic properties of a material that are conductivity, permittivity and permeability. MIT is categorized under the passive imaging family with an electrodeless technique through the use of excitation coils to induce an electromagnetic field in the material, which is then measured at the receiving side by sensors. The aim of this review is to discuss the challenges of the MIT technique and summarize the recent advancements in the transmitters and sensors, with a focus on applications in biological tissue imaging. It is hoped that this review will provide some valuable information on the MIT for those who have interest in this modality. The need of this knowledge may speed up the process of adopted of MIT as a medical imaging technology.

  10. Optical Magnetic Induction Tomography of the Heart

    PubMed Central

    Marmugi, Luca; Renzoni, Ferruccio

    2016-01-01

    Atrial Fibrillation (AF) affects a significant fraction of the ageing population, causing a high level of morbidity and mortality. Despite its significance, the causes of AF are still not uniquely identified. This, combined with the lack of precise diagnostic and guiding tools, makes the clinical treatment of AF sub-optimal. We identify magnetic induction tomography as the most promising technique for the investigation of the causes of fibrillation and for its clinical practice. We therefore propose a novel optical instrument based on optical atomic magnetometers, fulfilling the requirements for diagnostic mapping of the heart’s conductivity. The feasibility of the device is here discussed in view of the final application. Thanks to the potential of atomic magnetometers for miniaturisation and extreme sensitivity at room temperature, a new generation of compact and non-invasive diagnostic instrumentation, with both bedside and intra-operative operation capability, is envisioned. Possible scenarios both in clinical practice and biomedical research are then discussed. The flexibility of the system makes it promising also for application in other fields, such as neurology and oncology. PMID:27040727

  11. Optical Magnetic Induction Tomography of the Heart

    NASA Astrophysics Data System (ADS)

    Marmugi, Luca; Renzoni, Ferruccio

    2016-04-01

    Atrial Fibrillation (AF) affects a significant fraction of the ageing population, causing a high level of morbidity and mortality. Despite its significance, the causes of AF are still not uniquely identified. This, combined with the lack of precise diagnostic and guiding tools, makes the clinical treatment of AF sub-optimal. We identify magnetic induction tomography as the most promising technique for the investigation of the causes of fibrillation and for its clinical practice. We therefore propose a novel optical instrument based on optical atomic magnetometers, fulfilling the requirements for diagnostic mapping of the heart’s conductivity. The feasibility of the device is here discussed in view of the final application. Thanks to the potential of atomic magnetometers for miniaturisation and extreme sensitivity at room temperature, a new generation of compact and non-invasive diagnostic instrumentation, with both bedside and intra-operative operation capability, is envisioned. Possible scenarios both in clinical practice and biomedical research are then discussed. The flexibility of the system makes it promising also for application in other fields, such as neurology and oncology.

  12. Alternating current electromagnetic servo induction meter

    NASA Technical Reports Server (NTRS)

    Bogue, R. K.

    1968-01-01

    Electromagnetic device accurately indicates the responses of various sensors in high performance flight research aircraft to conditions encountered in flight. The device responds to sensor inputs to move a slideable armature along an indicator scale by the force of currents induced in the armature winding.

  13. Why Ampère did not discover electromagnetic induction

    NASA Astrophysics Data System (ADS)

    Williams, L. Pearce

    1986-04-01

    In 1832, after Michael Faraday had announced his discovery of electromagnetic induction, Andre-Marie Ampère claimed that he had actually discovered the induction of one current by another in 1822. In fact, he had, but did not really publish the fact at that time. This article explores the reasons for Ampère's failure to lay claim to a discovery that would have guaranteed him scientific immortality.

  14. Electromagnetic induction imaging with a radio-frequency atomic magnetometer

    NASA Astrophysics Data System (ADS)

    Deans, Cameron; Marmugi, Luca; Hussain, Sarah; Renzoni, Ferruccio

    2016-03-01

    We report on a compact, tunable, and scalable to large arrays imaging device, based on a radio-frequency optically pumped atomic magnetometer operating in magnetic induction tomography modality. Imaging of conductive objects is performed at room temperature, in an unshielded environment and without background subtraction. Conductivity maps of target objects exhibit not only excellent performance in terms of shape reconstruction but also demonstrate detection of sub-millimetric cracks and penetration of conductive barriers. The results presented here demonstrate the potential of a future generation of imaging instruments, which combine magnetic induction tomography and the unmatched performance of atomic magnetometers.

  15. Investigation of an Electromagnetic Induction Sensor

    DTIC Science & Technology

    2011-12-01

    Our initial tests on simulated , laboratory and field data indicate that target depth information can be extracted from EMI data with small errors... laboratory positioner was developed with three automated translational stages (x, y, and z), two automated rotational stages (yaw and pitch), and one ...Symposium on Aerospace/Defense Sensing, Simulation , and Controls, Vol. 6217, Orlando, FL, April 2006. 2. Waymond R. Scott, Jr., “Electromagnetic

  16. The Teaching of Electromagnetic Induction at Sixth Form Level

    ERIC Educational Resources Information Center

    Archenhold, W. F.

    1974-01-01

    Presents some ideas about teaching electromagnetic induction at sixth form level, including educational objectives, learning difficulties, syllabus requirements, selection of unit system, and sequence of material presentation. Suggests the Education Group of the Institute of Physics hold further discussions on these aspects before including the…

  17. Imaging cerebral haemorrhage with magnetic induction tomography: numerical modelling.

    PubMed

    Zolgharni, M; Ledger, P D; Armitage, D W; Holder, D S; Griffiths, H

    2009-06-01

    Magnetic induction tomography (MIT) is a new electromagnetic imaging modality which has the potential to image changes in the electrical conductivity of the brain due to different pathologies. In this study the feasibility of detecting haemorrhagic cerebral stroke with a 16-channel MIT system operating at 10 MHz was investigated. The finite-element method combined with a realistic, multi-layer, head model comprising 12 different tissues, was used for the simulations in the commercial FE package, Comsol Multiphysics. The eddy-current problem was solved and the MIT signals computed for strokes of different volumes occurring at different locations in the brain. The results revealed that a large, peripheral stroke (volume 49 cm(3)) produced phase changes that would be detectable with our currently achievable instrumentation phase noise level (17 m degrees ) in 70 (27%) of the 256 exciter/sensor channel combinations. However, reconstructed images showed that a lower noise level than this, of 1 m degrees , was necessary to obtain good visualization of the strokes. The simulated MIT measurements were compared with those from an independent transmission-line-matrix model in order to give confidence in the results.

  18. Electromagnetic induction studies. [of earth lithosphere and asthenosphere

    NASA Technical Reports Server (NTRS)

    Hermance, J. F.

    1983-01-01

    Recent developments in electromagnetic induction studies of the lithosphere and the asthenosphere are reviewed. Attention is given to geoelectrical studies of active tectonic areas in terms of the major zones of crustal extension, the basin and range province along western regions of North America, and the Rio Grande rift. Studies have also been performed of tectonic activity around Iceland, the Salton Trough and Cerro Prieto, and the subduction zones of the Cascade Mountains volcanic belt, where magnetotelluric and geomagnetic variation studies have been done. Geomagnetic variations experiments have been reported in the Central Appalachians, and submarine electromagnetic studies along the Juan de Fuca ridge. Controlled source electromagnetic and dc resistivity investigations have been carried out in Nevada, Hawaii, and in the Adirondacks Mountains. Laboratory examinations on the conductivity of representative materials over a broad range of temperature, pressure, and chemistry are described.

  19. Optical atomic magnetometry for magnetic induction tomography of the heart

    NASA Astrophysics Data System (ADS)

    Deans, Cameron; Marmugi, Luca; Hussain, Sarah; Renzoni, Ferruccio

    2016-04-01

    We report on the use of radio-frequency optical atomic magnetometers for magnetic induction tomography measurements. We demonstrate the imaging of dummy targets of varying conductivities placed in the proximity of the sensor, in an unshielded environment at room-temperature and without background subtraction. The images produced by the system accurately reproduce the characteristics of the actual objects. Furthermore, we perform finite element simulations in order to assess the potential for measuring low-conductivity biological tissues with our system. Our results demonstrate the feasibility of an instrument based on optical atomic magnetometers for magnetic induction tomography imaging of biological samples, in particular for mapping anomalous conductivity in the heart.

  20. Electromagnetic fields and the induction of DNA strand breaks.

    PubMed

    Ruiz-Gómez, Miguel J; Martínez-Morillo, Manuel

    2009-01-01

    The International Agency for Research on Cancer (IARC) has classified the extremely low-frequency (ELF) electromagnetic fields (EMF) as "possible carcinogenic" based on the reported effects. The purpose of this work is to review and compare the recent findings related to the induction of DNA strand breaks (DNA-SB) by magnetic field (MF) exposure. We found 29 studies (genotoxic and epigenetic) about the induction of DNA-SB by MF. 50% showed effect of MF and 50% showed no DNA-SB. Nevertheless, considering only genotoxic or only epigenetic studies, 37.5% and 69.2% found induction of DNA-SB by MF, respectively. In relation to these data it seems that MF could act as a co-inductor of DNA damage rather than as a genotoxic agent per se. Nevertheless, the published results, in some cases conflicting with negative findings, do not facilitate to obtain a common consensus about MF effects and biophysical interaction mechanisms.

  1. Instability of induction cooker (electromagnetic stove) antigen retrieval in immunohistochemistry.

    PubMed

    Ding, Wei; Zheng, Xiang-Yi

    2012-03-01

    An induction cooker is a modern electric cooker that takes electromagnetic induction principle to heat. As it has high efficiency, no open flame, and is safe and convenient, more and more laboratories use it as an antigen retrieval heating tool in immunohistochemistry. We found that there was still some instability with the induction cooker, because with certain antigens the power change influenced the results of immunohistochemistry staining, showing weaker staining intensity or decreased number of positive cells, but which were not entirely negative. For some antigens, it had no influence on results. The instability of this heating tool for antigen retrieval was caused partly by negligent operators, and which may influence the experimental results and the pathologic diagnosis.

  2. Reconstruction of velocity fields in electromagnetic flow tomography.

    PubMed

    Lehtikangas, Ossi; Karhunen, Kimmo; Vauhkonen, Marko

    2016-06-28

    Electromagnetic flow meters (EMFMs) are the gold standard in measuring flow velocity in process industry. The flow meters can measure the mean flow velocity of conductive liquids and slurries. A drawback of this approach is that the velocity field cannot be determined. Asymmetric axial flows, often encountered in multiphase flows, pipe elbows and T-junctions, are problematic and can lead to serious systematic errors. Recently, electromagnetic flow tomography (EMFT) has been proposed for measuring velocity fields using several coils and a set of electrodes attached to the surface of the pipe. In this work, a velocity field reconstruction method for EMFT is proposed. The method uses a previously developed finite-element-based computational forward model for computing boundary voltages and a Bayesian framework for inverse problems. In the approach, the vz-component of the velocity field along the longitudinal axis of the pipe is estimated on the pipe cross section. Different asymmetric velocity fields encountered near pipe elbows, solids-in-water flows in inclined pipes and in stratified or multiphase flows are tested. The results suggest that the proposed reconstruction method could be used to estimate velocity fields in complicated pipe flows in which the conventional EMFMs have limited accuracy. This article is part of the themed issue 'Supersensing through industrial process tomography'.

  3. Autaptic regulation of electrical activities in neuron under electromagnetic induction

    PubMed Central

    Xu, Ying; Ying, Heping; Jia, Ya; Ma, Jun; Hayat, Tasawar

    2017-01-01

    Realistic neurons may hold complex anatomical structure, for example, autapse connection to some internuncial neurons, which this specific synapse can connect to its body via a close loop. Continuous exchanges of charged ions across the membrane can induce complex distribution fluctuation of intracellular and extracellular charged ions of cell, and a time-varying electromagnetic field is set to modulate the membrane potential of neuron. In this paper, an autapse-modulated neuron model is presented and the effect of electromagnetic induction is considered by using magnetic flux. Bifurcation analysis and sampled time series for membrane potentials are calculated to investigate the mode transition in electrical activities and the biological function of autapse connection is discussed. Furthermore, the Gaussian white noise and electromagnetic radiation are considered on the improved neuron model, it is found appropriate setting and selection for feedback gain and time delay in autapse can suppress the bursting in neuronal behaviors. It indicates the formation of autapse can enhance the self-adaption of neuron so that appropriate response to external forcing can be selected, this biological function is helpful for encoding and signal propagation of neurons. It can be useful for investigation about collective behaviors in neuronal networks exposed to electromagnetic radiation. PMID:28240314

  4. Autaptic regulation of electrical activities in neuron under electromagnetic induction.

    PubMed

    Xu, Ying; Ying, Heping; Jia, Ya; Ma, Jun; Hayat, Tasawar

    2017-02-27

    Realistic neurons may hold complex anatomical structure, for example, autapse connection to some internuncial neurons, which this specific synapse can connect to its body via a close loop. Continuous exchanges of charged ions across the membrane can induce complex distribution fluctuation of intracellular and extracellular charged ions of cell, and a time-varying electromagnetic field is set to modulate the membrane potential of neuron. In this paper, an autapse-modulated neuron model is presented and the effect of electromagnetic induction is considered by using magnetic flux. Bifurcation analysis and sampled time series for membrane potentials are calculated to investigate the mode transition in electrical activities and the biological function of autapse connection is discussed. Furthermore, the Gaussian white noise and electromagnetic radiation are considered on the improved neuron model, it is found appropriate setting and selection for feedback gain and time delay in autapse can suppress the bursting in neuronal behaviors. It indicates the formation of autapse can enhance the self-adaption of neuron so that appropriate response to external forcing can be selected, this biological function is helpful for encoding and signal propagation of neurons. It can be useful for investigation about collective behaviors in neuronal networks exposed to electromagnetic radiation.

  5. Autaptic regulation of electrical activities in neuron under electromagnetic induction

    NASA Astrophysics Data System (ADS)

    Xu, Ying; Ying, Heping; Jia, Ya; Ma, Jun; Hayat, Tasawar

    2017-02-01

    Realistic neurons may hold complex anatomical structure, for example, autapse connection to some internuncial neurons, which this specific synapse can connect to its body via a close loop. Continuous exchanges of charged ions across the membrane can induce complex distribution fluctuation of intracellular and extracellular charged ions of cell, and a time-varying electromagnetic field is set to modulate the membrane potential of neuron. In this paper, an autapse-modulated neuron model is presented and the effect of electromagnetic induction is considered by using magnetic flux. Bifurcation analysis and sampled time series for membrane potentials are calculated to investigate the mode transition in electrical activities and the biological function of autapse connection is discussed. Furthermore, the Gaussian white noise and electromagnetic radiation are considered on the improved neuron model, it is found appropriate setting and selection for feedback gain and time delay in autapse can suppress the bursting in neuronal behaviors. It indicates the formation of autapse can enhance the self-adaption of neuron so that appropriate response to external forcing can be selected, this biological function is helpful for encoding and signal propagation of neurons. It can be useful for investigation about collective behaviors in neuronal networks exposed to electromagnetic radiation.

  6. Correlated noise and prior models in electromagnetic flow tomography

    NASA Astrophysics Data System (ADS)

    Lehtikangas, Ossi; Vauhkonen, Marko

    2017-04-01

    Electromagnetic flow meters are a gold standard in measuring the mean flow velocity of conductive liquids and slurries in process industry. A drawback of this approach is that the velocity field cannot be determined. Information about velocity fields is important for characterizing multiphase flows in the process industry. Recently, electromagnetic flow tomography (EMFT) has been proposed for measuring velocity fields using several coils and a set of electrodes attached to the inner surface of the pipe. The velocity field reconstruction method utilizes a finite element based computational forward model and a Bayesian framework for inverse problem. In the approach, a priori probability and noise models are written describing the flow and measurement error characteristics, respectively. In this work, the effect of additive, possibly correlated, measurement noise and different prior models on the velocity field reconstructions in EMFT are tested using numerical simulations. The results show that the velocity field reconstruction method produces feasible estimates even with relatively high level of correlated measurement noise if the covariance structure of the noise is taken into account. In practice, the noise covariance can be estimated from measurements using sample based methods. Moreover, it is shown that a smoothness prior using a squared exponential covariance function is in general a good choice for the prior model and more advanced prior models for specific flow types such as stratified or turbulent flows can be used.

  7. Microscale electromagnetic heating in heterogeneous energetic materials based on x-ray computed tomography

    SciTech Connect

    Kort-Kamp, W. J. M.; Cordes, N. L.; Ionita, A.; Glover, B. B.; Duque, A. L. Higginbotham; Perry, W. L.; Patterson, B. M.; Dalvit, D. A. R.; Moore, D. S.

    2016-04-01

    Electromagnetic stimulation of energetic materials provides a noninvasive and nondestructive tool for detecting and identifying explosives. We combine structural information based on x-ray computed tomography, experimental dielectric data, and electromagnetic full-wave simulations to study microscale electromagnetic heating of realistic three-dimensional heterogeneous explosives. In conclusion, we analyze the formation of electromagnetic hot spots and thermal gradients in the explosive-binder mesostructures and compare the heating rate for various binder systems.

  8. Scripted finite element tools for global electromagnetic induction studies

    NASA Astrophysics Data System (ADS)

    Ribaudo, Joseph T.; Constable, Catherine G.; Parker, Robert L.

    2012-02-01

    Numerical solution of global geomagnetic induction problems in two and three spatial dimensions can be conducted with commercially available, general-purpose, scripted, finite-element software. We show that FlexPDE is capable of solving a variety of global geomagnetic induction problems. The models treated can include arbitrary electrical conductivity of the core and mantle, arbitrary spatial structure and time behaviour of the primary magnetic field. A thin surface layer of laterally heterogeneous conductivity, representing the oceans and crust, may be represented by a boundary condition at the Earth-space interface. We describe a numerical test, or validation, of the program by comparing its output to analytic and semi-analytic solutions for several electromagnetic induction problems: (1) concentric spherical shells representing a layered Earth in a time-varying, uniform, external magnetic field, (2) eccentrically nested conductive spheres in the same field and (3) homogeneous spheres or cylinders, initially at rest, then rotating at a steady rate in a constant, uniform, external field. Calculations are performed in both the time and frequency domains, and in both 2-D and 3-D computational meshes, with adaptive mesh refinement. Root-mean-square accuracies of better than 1 per cent are achieved in all cases. A unique advantage of our technique is the ability to model Earth rotation in both the time and the frequency domain, which is especially useful for simulating satellite data.

  9. Analysis of Arguments Constructed by First-Year Engineering Students Addressing Electromagnetic Induction Problems

    ERIC Educational Resources Information Center

    Almudi, Jose Manuel; Ceberio, Mikel

    2015-01-01

    This study explored the quality of arguments used by first-year engineering university students enrolled in a traditional physics course dealing with electromagnetic induction and related problem solving where they had to assess whether the electromagnetic induction phenomenon would occur. Their conclusions were analyzed for the relevance of the…

  10. The Search for Electromagnetic Induction (1820-1831). Experiment No. 20.

    ERIC Educational Resources Information Center

    Devons, Samuel

    This paper focuses on the search for electromagnetic induction from 1820 to 1831 and the efforts by Augustin Fresnel's colleague, Andre Marie Ampere, in electric and magnetic induction. Faraday's work is discussed with excerpts from his diary on electromagnetism. A variety of different experiments by researchers including Francoise Jean Arago,…

  11. Ballistocardiogram of avian eggs determined by an electromagnetic induction coil.

    PubMed

    Ono, H; Akiyama, R; Sakamoto, Y; Pearson, J T; Tazawa, H

    1997-07-01

    As an avian embryo grows within an eggshell, the whole egg is moved by embryonic activity and also by the embryonic heartbeat. A technical interest in detecting minute biological movements has prompted the development of techniques and systems to measure the cardiogenic ballistic movement of the egg or ballistocardiogram (BCG). In this context, there is interest in using an electromagnetic induction coil (solenoid) as another simple sensor to measure the BCG and examining its possibility for BCG measurement. A small permanent magnet is attached tightly to the surface of an incubated egg, and then the egg with the magnet is placed in a solenoid. Preliminary model analysis is made to design a setup of the egg, magnet and solenoid coupling system. Then, simultaneous measurement with a laser displacement measuring system, developed previously, is made for chicken eggs, indicating that the solenoid detects the minute cardiogenic ballistic movements and that the BCG determined is a measure of the velocity of egg movements.

  12. Model simulations of possible electromagnetic induction effects at Magsat activities

    NASA Technical Reports Server (NTRS)

    Hermance, J. F.

    1982-01-01

    Model simulations are used in a consideration of whether terrestrial induced-current magnetic field effects are significant for near-earth satellite observation, and the nature of the effect at satellite altitudes of lateral differences in the gross conductivity structure of the earth. It is shown that induction in a spherical earth by distant magnetospheric sources can contribute magnetic field fluctuations at Magsat orbit altitudes which are 30-40% of external field amplitudes. It is found that, when phenomenon dimensions are small by comparison with the earth's radius, the earth may be approximated by a plane, horizontal half-space by which electromagnetic energy is reflected with nearly 100% efficiency from the surface. This implies that while the total horizontal field is twice the source field when the source is above the satellite, it is reduced to values smaller than the source field when the source is below the satellite and tends to enhance gross electrical discontinuity signatures in the lithosphere.

  13. An electromagnetic induction method for underground target detection and characterization

    SciTech Connect

    Bartel, L.C.; Cress, D.H.

    1997-01-01

    An improved capability for subsurface structure detection is needed to support military and nonproliferation requirements for inspection and for surveillance of activities of threatening nations. As part of the DOE/NN-20 program to apply geophysical methods to detect and characterize underground facilities, Sandia National Laboratories (SNL) initiated an electromagnetic induction (EMI) project to evaluate low frequency electromagnetic (EM) techniques for subsurface structure detection. Low frequency, in this case, extended from kilohertz to hundreds of kilohertz. An EMI survey procedure had already been developed for borehole imaging of coal seams and had successfully been applied in a surface mode to detect a drug smuggling tunnel. The SNL project has focused on building upon the success of that procedure and applying it to surface and low altitude airborne platforms. Part of SNL`s work has focused on improving that technology through improved hardware and data processing. The improved hardware development has been performed utilizing Laboratory Directed Research and Development (LDRD) funding. In addition, SNL`s effort focused on: (1) improvements in modeling of the basic geophysics of the illuminating electromagnetic field and its coupling to the underground target (partially funded using LDRD funds) and (2) development of techniques for phase-based and multi-frequency processing and spatial processing to support subsurface target detection and characterization. The products of this project are: (1) an evaluation of an improved EM gradiometer, (2) an improved gradiometer concept for possible future development, (3) an improved modeling capability, (4) demonstration of an EM wave migration method for target recognition, and a demonstration that the technology is capable of detecting targets to depths exceeding 25 meters.

  14. Professor Henry, Mr. Faraday, and the Hunt for Electromagnetic Induction

    NASA Astrophysics Data System (ADS)

    Moyer, Albert E.

    1997-04-01

    On different sides of the Atlantic but about the same time, Michael Faraday and Joseph Henry announced success in a quest that had preoccupied the scientific community for a decade: coaxing electricity from magnetism. "Mutual induction," what Faraday and Henry had identified in the early 1830s, would turn out to be not only a foundational concept in the physics of electricity and magnetism but also the principle behind the technology of electrical transformers and generators--two mainstays of industrialization. Although Faraday's breakthrough in London and Henry's in Albany might appear to be classic examples of "independent discovery," they were not. The two natural philosophers shared a similar orientation toward their research and, moreover, a distinctive laboratory instrument: Henry's new, powerful electromagnet. Thus, the story of Henry's and Faraday's search for induction illuminates not only the workings of Victorian science but also the crucial part that an instrument--the unadorned hardware--can play in scientific inquiry. Albert Moyer takes this story from his biography of Joseph Henry that Smithsonian Institution Press is about to publish in commemoration of the 200th anniversary of Henry's birth. The biography focuses on Henry's early and middle years, 1797-1847, from his emergence as America's foremost physical scientist to his election as the Smithsonian Institution's first director.

  15. Electromagnetic Induction in Rough Geologic Media: The Classical Approach

    NASA Astrophysics Data System (ADS)

    Weiss, C. J.; Everett, M. E.; Ge, J.

    2012-12-01

    Electromagnetic (EM) induction methods are well known to be sensitive indicators of electrically conducting subsurface mineral and fluid phases, responding to both the topological connectedness of the conducting phase and galvanic charge buildup on conductivity boundaries. Key to quantifying the relationship between electromagnetic signatures and the underlying the geohydrology is accurate representation of the infinitely complex, conducting Earth in terms of a finite set of model parameters and their associated physics. However, field observations of the spatial variability of induced EM fields and their inferred rate of diffusive propagation suggest that simple, piecewise smooth or continuous models of electrical conductivity -- as commonly depicted in numerical modeling -- may not fully capture the relevant electrodynamics in all geologic settings, especially those where the subsurface is characterized by multi-scale, hierarchical structures such as fractures. Consistent with such observations is a recasting of the Maxwell Equations in terms of fractional calculus, similar to that done routinely in hydrology for the transport equations to explain anomalous hydrologic diffusion, where the underlying multi-scale complexity is captured efficiently by only a few, simple, model parameters. This study focuses on how geo-complexity ultimately manifests its EM signature in a fractional-calculus sense through three-dimensional modeling of spatially-correlated stochastic realizations of the electrically conducting subsurface. Preliminary results simulating the response of a frequency-domain, loop-loop system suggest that heterogeneity proximal to the transmitting antenna generates a strong, but relatively smooth response in the near-field vertical magnetic induction when compared to that in the far field. This finding suggests an exploration strategy based on multi-offset observations may be relevant to quantifying the length scale over which the fractional calculus model

  16. Using computer simulations to facilitate conceptual understanding of electromagnetic induction

    NASA Astrophysics Data System (ADS)

    Lee, Yu-Fen

    This study investigated the use of computer simulations to facilitate conceptual understanding in physics. The use of computer simulations in the present study was grounded in a conceptual framework drawn from findings related to the use of computer simulations in physics education. To achieve the goal of effective utilization of computers for physics education, I first reviewed studies pertaining to computer simulations in physics education categorized by three different learning frameworks and studies comparing the effects of different simulation environments. My intent was to identify the learning context and factors for successful use of computer simulations in past studies and to learn from the studies which did not obtain a significant result. Based on the analysis of reviewed literature, I proposed effective approaches to integrate computer simulations in physics education. These approaches are consistent with well established education principles such as those suggested by How People Learn (Bransford, Brown, Cocking, Donovan, & Pellegrino, 2000). The research based approaches to integrated computer simulations in physics education form a learning framework called Concept Learning with Computer Simulations (CLCS) in the current study. The second component of this study was to examine the CLCS learning framework empirically. The participants were recruited from a public high school in Beijing, China. All participating students were randomly assigned to two groups, the experimental (CLCS) group and the control (TRAD) group. Research based computer simulations developed by the physics education research group at University of Colorado at Boulder were used to tackle common conceptual difficulties in learning electromagnetic induction. While interacting with computer simulations, CLCS students were asked to answer reflective questions designed to stimulate qualitative reasoning and explanation. After receiving model reasoning online, students were asked to submit

  17. The Use of Electromagnetic Induction Techniques for Soil Mapping

    NASA Astrophysics Data System (ADS)

    Brevik, Eric C.; Doolittle, Jim

    2015-04-01

    Soils have high natural spatial variability. This has been recognized for a long time, and many methods of mapping that spatial variability have been investigated. One technique that has received considerable attention over the last ~30 years is electromagnetic induction (EMI). Particularly when coupled with modern GPS and GIS systems, EMI techniques have allowed the rapid and relatively inexpensive collection of large spatially-related data sets that can be correlated to soil properties that either directly or indirectly influence electrical conductance in the soil. Soil electrical conductivity is directly controlled by soil water content, soluble salt content, clay content and mineralogy, and temperature. A wide range of indirect controls have been identified, such as soil organic matter content and bulk density; both influence water relationships in the soil. EMI techniques work best in areas where there are large changes in one soil property that influences soil electrical conductance, and don't work as well when soil properties that influence electrical conductance are largely homogenous. This presentation will present examples of situations where EMI techniques were successful as well as a couple of examples of situations where EMI was not so useful in mapping the spatial variability of soil properties. Reasons for both the successes and failures will be discussed.

  18. Projectile transverse motion and stability in electromagnetic induction launchers

    SciTech Connect

    Shokair, I.R.

    1993-08-01

    The transverse motion of a projectile in an electromagnetic induction launcher is considered. The equations of motion for translation and rotation are derived assuming a rigid projectile and a flyway restoring force per unit length that is proportional to the local displacement. Transverse forces and torques due to energized coils are derived for displaced or tilted projectile elements based on a first order perturbation method. The resulting equations of motion for a rigid projectile composed of multiple elements in a multi-coil launcher are analyzed as a coupled oscillator system of equations and a simple stability condition is derived. The equations of motion are incorporated into the 2-D Slingshot code and numerical solutions for the transverse motion are obtained. For the 20 meter navy launcher parameters we find that stability is achieved with a flyway spring constant of k {approx} 1{times} 10{sup 8} N/m{sup 2}. For k {approx} 1.5 {times} 10{sup 8} N/m{sup 2} and sample coil misalignment modeled as a sine wave of I mm amplitude at wavelengths of one or two meters, the projectile displacement grows to a maximum of 4 mm. This growth is due to resonance between the natural frequency of the Projectile transverse motion and the coil displacement wavelength. This resonance does not persist because of the changing axial velocity. Random coil displacement is also found to cause roughly the same projectile displacement. For the maximum displacement a rough estimate of the transverse pressure is 50 bars.

  19. Electromagnetic Induction Methods in Mining Geophysics from 2008 to 2012

    NASA Astrophysics Data System (ADS)

    Smith, Richard

    2014-01-01

    In the period from 2008 to 2012, the topic of electromagnetic (EM) induction methods applied to mineral exploration has been the subject of more than 50 papers in journals and more than 300 extended abstracts presented at conferences (about 100 of which contain developments worthy of mentioning). Most of the work at the universities has been on modelling, inversion and data processing, and most of this material is published in the refereed literature. However, academia has also undertaken work on system geometry changes, system calibration and sensor design. There have been papers describing new systems developed for mineral exploration and case histories describing the use of EM methods to directly discover mineral deposits or to map the geology. Most of this work is by the service companies and mining companies and reported in the unrefereed literature. Since 2008, the pace of development of helicopter time-domain systems has slowed and more effort has been directed to developing natural source magnetic systems and to modelling and inverting this data. A number of studies comparing the results from natural source methods with the results from artificial source methods conclude that the natural source methods can see large-scale geological structures usually when there is a weak conductivity contrast with the surrounding material, but the natural source methods are unable to see small features that have a very large conductivity contrast with the country rock. Hence, they are not a good detector of mineral deposits unless one is looking for a large porphyry system.

  20. Joseph Henry’s role in the discovery of electromagnetic induction

    NASA Astrophysics Data System (ADS)

    Smith, Glenn S.

    2017-01-01

    The discovery of electromagnetic induction in the early part of the 19th century is one of the greatest scientific achievements of all time, and it has had tremendous technological consequences. The credit for this discovery rightfully goes to the great English experimental physicist Michael Faraday. However, the American physicist Joseph Henry made some observations comparable to Faraday’s at nearly the same time, and for that reason, Faraday and Henry are often considered to be co-discoverers of some aspects of electromagnetic induction. We examine Henry’s early research on electromagnetism, starting from his efforts to improve the electromagnet, which led directly to his investigations of induction. We describe his earliest experiments on both mutual and self-induction, and pay particular attention to the relationship of Henry’s research to that of Faraday. The approach is one in which the experiments are described and then analysed using modern theory and terminology.

  1. Electromagnetic-induction logging to monitor changing chloride concentrations

    USGS Publications Warehouse

    Metzger, Loren F.; Izbicki, John A.

    2013-01-01

    Water from the San Joaquin Delta, having chloride concentrations up to 3590 mg/L, has intruded fresh water aquifers underlying Stockton, California. Changes in chloride concentrations at depth within these aquifers were evaluated using sequential electromagnetic (EM) induction logs collected during 2004 through 2007 at seven multiple-well sites as deep as 268 m. Sequential EM logging is useful for identifying changes in groundwater quality through polyvinyl chloride-cased wells in intervals not screened by wells. These unscreened intervals represent more than 90% of the aquifer at the sites studied. Sequential EM logging suggested degrading groundwater quality in numerous thin intervals, typically between 1 and 7 m in thickness, especially in the northern part of the study area. Some of these intervals were unscreened by wells, and would not have been identified by traditional groundwater sample collection. Sequential logging also identified intervals with improving water quality—possibly due to groundwater management practices that have limited pumping and promoted artificial recharge. EM resistivity was correlated with chloride concentrations in sampled wells and in water from core material. Natural gamma log data were used to account for the effect of aquifer lithology on EM resistivity. Results of this study show that a sequential EM logging is useful for identifying and monitoring the movement of high-chloride water, having lower salinities and chloride concentrations than sea water, in aquifer intervals not screened by wells, and that increases in chloride in water from wells in the area are consistent with high-chloride water originating from the San Joaquin Delta rather than from the underlying saline aquifer.

  2. Electromagnetic-induction logging to monitor changing chloride concentrations.

    PubMed

    Metzger, Loren F; Izbicki, John A

    2013-01-01

    Water from the San Joaquin Delta, having chloride concentrations up to 3590 mg/L, has intruded fresh water aquifers underlying Stockton, California. Changes in chloride concentrations at depth within these aquifers were evaluated using sequential electromagnetic (EM) induction logs collected during 2004 through 2007 at seven multiple-well sites as deep as 268 m. Sequential EM logging is useful for identifying changes in groundwater quality through polyvinyl chloride-cased wells in intervals not screened by wells. These unscreened intervals represent more than 90% of the aquifer at the sites studied. Sequential EM logging suggested degrading groundwater quality in numerous thin intervals, typically between 1 and 7 m in thickness, especially in the northern part of the study area. Some of these intervals were unscreened by wells, and would not have been identified by traditional groundwater sample collection. Sequential logging also identified intervals with improving water quality-possibly due to groundwater management practices that have limited pumping and promoted artificial recharge. EM resistivity was correlated with chloride concentrations in sampled wells and in water from core material. Natural gamma log data were used to account for the effect of aquifer lithology on EM resistivity. Results of this study show that a sequential EM logging is useful for identifying and monitoring the movement of high-chloride water, having lower salinities and chloride concentrations than sea water, in aquifer intervals not screened by wells, and that increases in chloride in water from wells in the area are consistent with high-chloride water originating from the San Joaquin Delta rather than from the underlying saline aquifer.

  3. Projectile transverse motion and stability in electromagnetic induction launchers

    SciTech Connect

    Shokair, I.R.

    1993-12-31

    The transverse motion of a projectile in an electromagnetic induction launcher is considered. The equations of motion for translation and rotation are derived assuming a rigid projectile and a flyway restoring force per unit length that is proportional to the local displacement. Linearized transverse forces and torques due to energized coils are derived for displaced or tilted armature elements based on a first order perturbation method. The resulting equations of motion for a rigid projectile composed of multiple elements in a multi-coil launcher are analyzed as a coupled oscillator system of equations and a simple linear stability condition is derived. The equations of motion are incorporated into the 2-D Slingshot circuit code and numerical solutions for the transverse motion are obtained. For a launcher with a 10 cm bore radius with a 40 cm long solid armature, we find that stability is achieved with a restoring force (per unit length) constant of k {approx} 1 {times} 10{sup 8} N/m{sup 2}. For k = 1.5 {times} 10{sup 8} N/m{sup 2} and sample coil misalignment modeled as a sine wave of 1 mm amplitude at wavelengths of one or two meters, the projectile displacement grows to a maximum of 4 mm. This growth is due to resonance between the natural frequency of the projectile transverse motion and the coil displacement wavelength. This resonance does not persist because of the changing axial velocity. Random coil displacement is also found to cause roughly the same projectile displacement. For the maximum displacement a rough estimate of the transverse pressure is 50 bars. Results for a wound armature with uniform current density throughout show very similar displacements.

  4. Contactless inductive flow tomography: basic principles and first applications in the experimental modelling of continuous casting

    NASA Astrophysics Data System (ADS)

    Stefani, F.; Eckert, S.; Ratajczak, M.; Timmel, K.; Wondrak, T.

    2016-07-01

    Contactless inductive flow tomography (CIFT) aims at reconstructing the flow structure of a liquid metal from the magnetic fields measured at various positions outside the fluid body which are induced by the flow under the influence of one or multiple applied magnetic fields. We recap the basic mathematical principles of CIFT and the results of an experiment in which the propeller-driven three-dimensional flow in a cylindrical had been reconstructed. We also summarize the recent activities to utilize CIFT in various problems connected with the experimental simulation of the continuous casting process. These include flow reconstructions in single-phase and two-phase flow problems in the Mini-LIMMCAST model of slab-casting, studies of the specific effects of an electromagnetic stirrer attached to the Submerged Entry Nozzle (SEN), as well as first successful applications of CIFT on the background of a strong electromagnetic brake field. We conclude by discussing some remaining obstacles for the deployment of CIFT in a real caster.

  5. A gradiometric version of contactless inductive flow tomography: theory and first applications.

    PubMed

    Ratajczak, Matthias; Wondrak, Thomas; Stefani, Frank

    2016-06-28

    The contactless inductive flow tomography (CIFT) is a measurement technique that allows reconstructing the flow of electrically conducting fluids by measuring the flow-induced perturbations of one or various applied magnetic fields and solving the underlying inverse problem. One of the most promising application fields of CIFT is the continuous casting of steel, for which the online monitoring of the flow in the mould would be highly desirable. In previous experiments at a small-scale model of continuous casting, CIFT has been applied to various industrially relevant problems, including the sudden changes of flow structures in case of argon injection and the influence of a magnetic stirrer at the submerged entry nozzle. The application of CIFT in the presence of electromagnetic brakes, which are widely used to stabilize the flow in the mould, has turned out to be more challenging due to the extreme dynamic range between the strong applied brake field and the weak flow-induced perturbations of the measuring field. In this paper, we present a gradiometric version of CIFT, relying on gradiometric field measurements, that is capable to overcome those problems and which seems, therefore, a promising candidate for applying CIFT in the steel casting industry. This article is part of the themed issue 'Supersensing through industrial process tomography'.

  6. Electromagnetic-Optical Coherence Tomography Guidance of Transbronchial Solitary Pulmonary Nodule Biopsy

    DTIC Science & Technology

    2014-07-01

    artificial SPN (aSPN) in living swine. 2. KEYWORDS Electromagnetic Navigation, Biopsy Guidance, Optical Microscopy, Optical Coherence Tomography, Lung ...acquired a CT scan of the lung verifying the visibility of the aSPN. 4c: Transbronchial needle biopsies of the artificial nodules will be acquired using...utilizing CT and electromagnetic (EM) navigation for spatial guidance to targeted lung nodules, and OCT for microscopic volumetric imaging. The OCT

  7. Reliability of electromagnetic induction data in near surface application

    NASA Astrophysics Data System (ADS)

    Nüsch, A.; Werban, U.; Sauer, U.; Dietrich, P.

    2012-12-01

    Use of the Electromagnetic Induction method for measuring electrical conductivities is widespread in applied geosciences, since the method is easy to perform and influenced by soil parameters. The vast amount of different applications of EMI measurements for different spatial resolutions as well as for the derivation of different soil parameters necessitates a unified handling of EMI data. So the requirements to the method have been changed from a qualitative overview to a quantitative use of data. A quantitative treatment of the data however is limited by the available instruments, which were made only for qualitative use. Nevertheless the limitations of the method can be expanded by considering a few conditions. In this study, we introduce possibilities for enhancing the quality of EMI data with regards to large scale investigations. In a set of systematic investigations, we show which aspects have to be taken into account when using a commercially available instrument, related to long term stability, comparability and repeatability. In-depth knowledge of the instruments used concerning aspects such as their calibration procedure, long term stability, battery life and thermal behaviour is an essential pre-requisite before starting the measurement process. A further aspect highlighted is quality control during measurements and if necessary a subsequent data correction which is pre-requisite for a quantitative analysis of the data. Quality control during the measurement process is crucial. Before a measurement starts, it is recommended that a short term test is carried out on-site to check environmental noise. Signal to noise ratio is a decisive influencing factor of whether or not the method is applicable at the chosen field site. A measurement needs to be monitored according to possible drifts. This can be achieved with different accuracies and starting from a quality check, with the help of reference lines up to a quantitative control with reference points

  8. Electromagnetic induction and damping: Quantitative experiments using a PC interface

    NASA Astrophysics Data System (ADS)

    Singh, Avinash; Mohapatra, Y. N.; Kumar, Satyendra

    2002-04-01

    A bar magnet, attached to an oscillating system, passes through a coil periodically, generating a series of electromotive force pulses. A novel method for the quantitative verification of Faraday's law is described which eliminates all errors associated with angular measurements, thereby revealing subtle features of the underlying mechanics. When electromagnetic damping is activated by short-circuiting the coil, a distinctly linear decay of the oscillation amplitude is observed. A quantitative analysis reveals an interesting interplay of the electromagnetic and mechanical time scales.

  9. A measurement system and image reconstruction in magnetic induction tomography.

    PubMed

    Vauhkonen, M; Hamsch, M; Igney, C H

    2008-06-01

    Magnetic induction tomography (MIT) is a technique for imaging the internal conductivity distribution of an object. In MIT current-carrying coils are used to induce eddy currents in the object and the induced voltages are sensed with other coils. From these measurements, the internal conductivity distribution of the object can be reconstructed. In this paper, we introduce a 16-channel MIT measurement system that is capable of parallel readout of 16 receiver channels. The parallel measurements are carried out using high-quality audio sampling devices. Furthermore, approaches for reconstructing MIT images developed for the 16-channel MIT system are introduced. We consider low conductivity applications, conductivity less than 5 S m(-1), and we use a frequency of 10 MHz. In the image reconstruction, we use time-harmonic Maxwell's equation for the electric field. This equation is solved with the finite element method using edge elements and the images are reconstructed using a generalized Tikhonov regularization approach. Both difference and static image reconstruction approaches are considered. Results from simulations and real measurements collected with the Philips 16-channel MIT system are shown.

  10. Transducer selection and application in magnetoacoustic tomography with magnetic induction

    NASA Astrophysics Data System (ADS)

    Zhou, Yuqi; Wang, Jiawei; Sun, Xiaodong; Ma, Qingyu; Zhang, Dong

    2016-03-01

    As an acoustic receiver, transducer plays a vital role in signal acquisition and image reconstruction for magnetoacoustic tomography with magnetic induction (MAT-MI). In order to optimize signal acquisition, the expressions of acoustic pressure detection and waveform collection are theoretically studied based on the radiation theory of acoustic dipole and the reception pattern of transducer. Pressure distributions are simulated for a cylindrical phantom model using a planar piston transducer with different radii and bandwidths. The proposed theory is also verified by the experimental measurements of acoustic waveform detection for an aluminum foil cylinder. It is proved that acoustic pressure with sharp and clear boundary peaks can be detected by the large-radius transducer with wide bandwidth, reflecting the differential of the induced Lorentz force accurately, which is helpful for precise conductivity reconstruction. To detect acoustic pressure with acceptable pressure amplitude, peak pressure ratio, amplitude ratio, and improved signal to noise ratio, the scanning radius of 5-10 times the radius of the object should be selected to improve the accuracy of image reconstruction. This study provides a theoretical and experimental basis for transducer selection and application in MAT-MI to obtain reconstructed images with improved resolution and definition.

  11. Perspectives of Increasing Efficiency and Productivity of Electromagnetic Induction Pumps for Mercury Basing on Permanent Magnets

    SciTech Connect

    Bucenieks, I.

    2006-07-01

    In the next generation neutron sources the HLM (heavy liquid metals) such as lead, lead based eutectic alloys and mercury will be used both as spallation target material and simultaneously as the cooling liquid. In this aspect the design of safe and effective pumps for HLM recirculation at high pressure heads and big flow rates becomes important. For this purpose electromagnetic inductions pumps having no problems of hydraulic seals being in contact with liquid metal (electromagnetic forces in the liquid metal are induced by magnetic system located outside of the channel of pump) are more perspective from the point of view of their safety for operation at high temperature and radiation conditions in comparison with mechanical pumps. At the Institute of Physics of University of Latvia (IPUL) the design concept of electromagnetic induction pumps basing on the principle of rotating permanent magnets (PMP) have been developed. Such design concept of electromagnetic induction pumps has many advantages in comparison with traditionally used electromagnetic induction pumps basing on 3-phase linear flat or cylindrical inductors. The estimations of parameters of powerful pumps (such as overall dimensions of the active magnetic system, power of motor needed for pump drive, the efficiency of pump) for mercury for the developed by pump pressure heads in the range up to 10.0 bar and provided flow rates in the range up to 20 litres per second are demonstrated. (author)

  12. Comparison of Airborne Electromagnetic Induction and Subsurface Radar Sounding of Freshwater Bathymetry

    DTIC Science & Technology

    1993-05-01

    AD-A268 703 Comparison of Airborne * Electromagnetic Induction and Subsurface Radar Sounding of Freshwater Bathymetry Austin Kovacs and J , Scott Holladay...Laboratory Comparison of Airborne Electromagnefic Induction and Subsurface Radar Sounding of Freshwater Bcdhymetry Austin Kovacs and J . Scott Holladay May 1993...Engineer, of the Applied Research Branch, Experimental Engineering Division, U.S. Army Cold Regions Research and Engineering Laboratory, and J . Scott Holladay

  13. Pedemis: A Portable Electromagnetic Induction Sensor with Integrated Positioning

    DTIC Science & Technology

    2012-04-27

    12211 Research Triangle Park, NC 27709-2211 15. SUBJECT TERMS PEDEMIS Benjamin E. Barrowes, Fridon Shubitidze, Tomasz M. Grzegorczyk, Pablo Fernandez ...Integrated Positioning Benjamin E. Barrowesa,b, Fridon Shubitidzeb, Tomasz M. Grzegorczykc, Pablo Fernándezb, and Kevin O’Neilla,b aUSACE-ERDC-CRREL, 72 Lyme...Barrowes, B. E., Shubitidze, F., Fernandez , J. P., and O’Neill, K., “Simultaneous identification of multiple unexploded ordnance using electromagnetic

  14. ALLTEM Multi-Axis Electromagnetic Induction System Demonstration and Validation

    DTIC Science & Technology

    2012-08-01

    threshold T-high higher threshold TMGS Tensor Magnetic Gradiometer System TOI target of interest Tx ALLTEM transmitter USGS U.S. Geological...the Tensor Magnetic Gradiometer System (TMGS) and two prototype EMI instruments, the Very Early Time-domain ElectroMagnetic (VETEM) system and the...horizontal directions (Hx and Hy). Because a transmitter is always on, opposite Rx loops are paired as gradiometers to cancel the primary field. 6 As a

  15. Feasibility study of an MR damper-based smart passive control system employing an electromagnetic induction device

    NASA Astrophysics Data System (ADS)

    Choi, Kang-Min; Jung, Hyung-Jo; Lee, Heon-Jae; Cho, Sang-Won

    2007-12-01

    The feasibility of a newly developed smart passive control system equipped electromagnetic induction device is experimentally investigated. An electromagnetic induction device consists of a permanent magnet and a solenoid, which produces electrical energy (i.e. induced current) according to Faraday's law of electromagnetic induction. The produced energy is applied to the magnetorheological (i.e. MR) damper to change the damping characteristics by itself without any controller or corresponding sensors for reducing structural responses. Recently, the smart passive control system was conceptually and numerically introduced without consideration of its practical applicability. This paper describes the design of an electromagnetic inductive device which is composed of a permanent magnet and a solenoid, and experiments with the MR damper-based smart passive control system on a shaking table which produces various sinusoidal and random excitations. The experimental results demonstrate that it is feasible to apply the smart passive control system equipped electromagnetic induction device for changing the damping characteristics of an MR damper.

  16. Using a PC and External Media to Quantitatively Investigate Electromagnetic Induction

    ERIC Educational Resources Information Center

    Bonanno, A.; Bozzo, G.; Camarca, M.; Sapia, P.

    2011-01-01

    In this article we describe an experimental learning path about electromagnetic induction which uses an Atwood machine where one of the two hanging bodies is a cylindrical magnet falling through a plexiglass guide, surrounded either by a coil or by a copper pipe. The first configuration (magnet falling across a coil) allows students to…

  17. Chapter 9.5: Electromagnetic induction to manage cattle feedlot waste

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This book chapter summarizes results of waste management research that utilized electromagnetic induction (EMI) tools for the purposes of: 1) collection of solid waste from feedlot surfaces to be utilized by crops 2) control and utilization of nutrient laden liquid runoff, and 3) feedlot surface man...

  18. Electromagnetic induction in spherical cap current layers under lunar and terrestrial conditions

    NASA Technical Reports Server (NTRS)

    Schubert, G.; Schwartz, K.

    1975-01-01

    Attention is given to electromagnetic induction in infinitesimally thin spherical cap current layers of arbitrary size and arbitrary axisymmetric integrated conductivity, taking into account a location at nonzero but otherwise arbitrary depth beneath the surface of observation. The description of a theoretical model is presented and the induced fields computed from the theoretical formulas for several different spherical cap models are discussed.

  19. A Datalogger Demonstration of Electromagnetic Induction with a Falling, Oscillating and Swinging Magnet

    ERIC Educational Resources Information Center

    Wong, Darren; Lee, Paul; Foong, See Kit

    2010-01-01

    We investigate the electromagnetic induction phenomenon for a "falling," "oscillating" and "swinging" magnet and a coil, with the help of a datalogger. For each situation, we discuss the salient aspects of the phenomenon, with the aid of diagrams, and relate the motion of the magnet to its mathematical and graphical representations. Using various…

  20. Electromagnetic Induction Sensor Data to Identify Areas of Manure Accumulation on a Feedlot Surface

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A study was initiated to test the validity of using electromagnetic induction (EMI) survey data, a prediction-based sampling strategy and ordinary linear regression modeling to predict spatially variable feedlot surface manure accumulation. A 30 m × 60 m feedlot pen with a central mound was selecte...

  1. Electromagnetic Induction Survey at an Archaeological Site in Chapingo (Central Mexico)

    NASA Astrophysics Data System (ADS)

    Salas, J. L.; Arango, C.; Cabral-Cano, E.; Arciniega-Ceballos, A.; Vergara, F.; Novo, X.

    2013-05-01

    The aim of this work is to locate buried remains of ancient civil constructions belonging to the Teotihuacan culture in Chapingo, Central Mexico. Several housing structures of this culture have been found during the excavation of a pipe trench within the University of Chapingo campus in the town of Chapingo. These units were found at 6 m deep covered by recent lacustrine sediments. In order to further explore the extension of this settlement that could guide further excavations and shed more light into these settlements, we have initiated a multi technique geophysical exploration. Here we present the initial results from this survey. An electromagnetic induction survey (EMI) was carried out to characterize the subsurface in an area of about 16,000 m2. We used a GF Instruments CMD-4 conductivity meter to map the horizontal distribution of the subsurface electrical conductivity. This instrument was operated in a continuous mode and linked to a single frequency GPS receiver attached to the probe to georeference the survey. The distance between the probe coils was 3.77 m and the investigation depth range was 4-6 m. The resulting electrical conductivity map shows two low conductivity zones with a NW-SE orientation. The inphase map also presented these characteristics. Since the electrical conductivity is associated with the material compaction, low conductivity values are expected for highly consolidated material; thus our results suggest that these low conductivity features could be related to areas that were the soil was compacted to serve as foundation of these ancient structures. The EMI survey present good initial results and will be expanded along with other techniques such as electrical tomography and ground penetrating radar in the near future in order to better map the extend of Teotihuacan culture in the region.

  2. Dynamical responses in a new neuron model subjected to electromagnetic induction and phase noise

    NASA Astrophysics Data System (ADS)

    Wu, Fuqiang; Wang, Chunni; Jin, Wuyin; Ma, Jun

    2017-03-01

    Complex electrical activities in neuron can induce time-varying electromagnetic field and the effect of various electromagnetic inductions should be considered in dealing with electrical activities of neuron. Based on an improved neuron model, the effect of electromagnetic induction is described by using magnetic flux, and the modulation of magnetic flux on membrane potential is realized by using memristor coupling. Furthermore, additive phase noise is imposed on the neuron to detect the dynamical response of neuron and phase transition in modes. The dynamical properties of electrical activities are detected and discussed, and double coherence resonance behavior is observed, respectively. Furthermore, multiple modes of electrical activities can be observed in the sampled time series for membrane potential of the neuron model.

  3. Electromagnetic interference of implantable unipolar cardiac pacemakers by an induction oven.

    PubMed

    Hirose, Minoru; Hida, Mizuho; Sato, Eiji; Kokubo, Kenichi; Nie, Masaki; Kobayashi, Hirosuke

    2005-06-01

    Induction ovens have been reported to exert electromagnetic interference on implanted cardiac pacemakers. In an attempt to quantitatively investigate the electromagnetic interference caused by an induction oven on implantable unipolar cardiac pacemakers, we measured the distribution profile of the magnetic field intensity, both with and without a pan on the induction oven. We also performed the inhibition test and asynchronous test using four kinds of pacemakers housed in the standardized Irnich human body model, and measured the maximal distance from the induction oven up to which the interference occurred. In the pan-detection mode of the oven in the absence of a pan, the distribution profile of the magnetic field intensity peaked at the center of the cooking plate, and during induction heating of a pan placed on the induction oven, it was the largest at the circular top-edge of the pan. Pacemaker pulses were inhibited by the induction oven, or generated by the reversion mechanism. The maximal interference distance from the oven was 34 cm for one of the pacemakers. Thus, the safe distance from an induction oven of a patient with an implanted cardiac pacemaker is considered to be 50 cm or more. In conclusion, in the pan-detection mode of the oven in the absence of a pan, the distribution profile of the magnetic field intensity peaked at the center of the cooking plate, and during the induction heating of a pan placed on the oven, it peaked at the circular edge of the pan. The induction oven asynchronized or generated pulses in implantable unipolar cardiac pacemakers up to a maximal distance of 34 cm from the induction oven.

  4. Global electromagnetic induction in the moon and planets. [poloidal eddy current transient response

    NASA Technical Reports Server (NTRS)

    Dyal, P.; Parkin, C. W.

    1973-01-01

    Experiments and analyses concerning electromagnetic induction in the moon and other extraterrestrial bodies are summarized. The theory of classical electromagnetic induction in a sphere is first considered, and this treatment is extended to the case of the moon, where poloidal eddy-current response has been found experimentally to dominate other induction modes. Analysis of lunar poloidal induction yields lunar internal electrical conductivity and temperature profiles. Two poloidal-induction analytical techniques are discussed: a transient-response method applied to time-series magnetometer data, and a harmonic-analysis method applied to data numerically Fourier-transformed to the frequency domain, with emphasis on the former technique. Attention is given to complicating effects of the solar wind interaction with both induced poloidal fields and remanent steady fields. The static magnetization field induction mode is described, from which are calculated bulk magnetic permeability profiles. Magnetic field measurements obtained from the moon and from fly-bys of Venus and Mars are studied to determine the feasibility of extending theoretical and experimental induction techniques to other bodies in the solar system.

  5. Electromagnetic, complex image model of a large area RF resonant antenna as inductive plasma source

    NASA Astrophysics Data System (ADS)

    Guittienne, Ph; Jacquier, R.; Howling, A. A.; Furno, I.

    2017-03-01

    A large area antenna generates a plasma by both inductive and capacitive coupling; it is an electromagnetically coupled plasma source. In this work, experiments on a large area planar RF antenna source are interpreted in terms of a multi-conductor transmission line coupled to the plasma. This electromagnetic treatment includes mutual inductive coupling using the complex image method, and capacitive matrix coupling between all elements of the resonant network and the plasma. The model reproduces antenna input impedance measurements, with and without plasma, on a 1.2× 1.2 m2 antenna used for large area plasma processing. Analytic expressions are given, and results are obtained by computation of the matrix solution. This method could be used to design planar inductive sources in general, by applying the termination impedances appropriate to each antenna type.

  6. Electromagnetic induction in the New Zealand South Island

    NASA Astrophysics Data System (ADS)

    Chen, J.; Dosso, H. W.; Ingham, M.

    1993-12-01

    Laboratory magnetic field measurements for a scaled analogue model of New Zealand and the surrounding oceans are used to provide induction arrows for simulated geomagnetic variations of 5-120 min periods for a series of traverses over the South Island. As the island is relatively narrow, the field responses for all on-land locations show significant effects of the surrounding oceans. The model simulates a uniformly resistive island, the oceans, and a conductive asthenosphere at depth, and thus discrepancies between the model and field results for sites on the island are attributed to anomalous geological structures not simulated in the model. Removing the coast effects before interpretation, by subtracting the model induction arrows from the field site arrows at Eyrewell permits an obvious reinterpretation that attributes a significant component of the field responses to the nearby Alpine and Marlborough Faults, rather than to the channelled current in Cook Strait.

  7. Electromagnetic interference with a bipolar pacemaker by an induction heating (IH) rice cooker.

    PubMed

    Nagatomo, Toshihisa; Abe, Haruhiko; Kohno, Ritsuko; Toyoshima, Takeshi; Fujimoto, Hiroshi; Kondo, Shoichi; Kabashima, Narutoshi; Takeuchi, Masaaki; Tamura, Masahito; Okazaki, Masahiro; Otsuji, Yutaka

    2009-01-01

    Electromagnetic fields may interfere with normal pacemaker function. Despite new device designs and bipolar leads, electromagnetic interference (EMI) remains a concern when pacemaker recipients are exposed to various household appliances. We report the observation of EMI by an induction heating (IH) rice cooker in a patient with sick sinus syndrome who was the recipient of a bipolar dual chamber-pacing system. Stored electrograms revealed episodes of inappropriate ventricular pacing, all coinciding with the opening of an IH rice cooker. Recipients of implantable medical devices must be warned to handle IH rice cookers with caution.

  8. General information for operation of the high-temperature electromagnetic containerless vacuum induction furnace

    SciTech Connect

    Hahs, C.A.; Fox, R.J.

    1994-06-01

    The High-Temperature Electromagnetic Containerless Vacuum Induction Furnace was developed at Oak Ridge National Laboratory for the National Aeronautics and Space Administration (NASA), Marshall Space Flight Center, Alabama. The high-efficiency radio-frequency system developed for the conceptual design of the Modular Electromagnetic Levitator was created to evaluate this hardware on the KC135 microgravity airplane operated by NASA. Near-future KC135 flights are being planned to levitate, melt, and undercool 5-mm samples of niobium. General information on the operation of this hardware is included.

  9. A perturbation expansion approach to solving the electromagnetic induction problem in three dimensions.

    SciTech Connect

    Tobin, Harold; Natek, Nancy H.; Weiss, Chester Joseph

    2003-10-01

    We address the electromagnetic induction problem for fully 3D geologic media and present a solution to the governing Maxwell equations based on a power series expansion. The coefficients in the series are computed using the adjoint method assuming an underlying homogeneous reference model. These solutions are available analytically for point dipole source terms and lead to rapid calculation of the expansion coefficients. First order solutions are presented for a model study in petroleum geophysics composed of a multi-component induction sonde proximal to a fault within a compartmentalized hydrocarbon reservoir.

  10. Magnetic and Electromagnetic Induction Effects in the Annual Means of Geomagnetic Elements

    NASA Technical Reports Server (NTRS)

    Demetrescu, Crisan; Andreescu, Maria

    1992-01-01

    The solar-cycle related (SC) variation in the annual means of the horizontal and vertical components of the geomagnetic field at European observatories is used to infer information on the magnetic and electric properties of the interior, characteristic of the observatory location, by identifying and analyzing the magnetic induction component and respectively the electromagnetic induction component of the SC variation. The obtained results and the method can be used to better constrain the anomaly bias in main field modelling and to improve the reliability of secular variation models beyond the time interval covered by data.

  11. Usefulness of electromagnetic induction type of force transducer and actuator for myofibril mechanics.

    PubMed

    Kimura, Kazushige; Abe, Takahiro; Phan, Kien Nguyen; Kobayashi, Takakazu

    2012-01-01

    A high performance device for measuring force and length change during myofibril contraction is fabricated. The principle of a device depends on the law of electromagnetic induction. Homogenized myofibrils were attached between two wires exposed in the uniform magnetic field by silicon adhesive under an inverted microscope. The purpose of this study is to examine performance whether the electromagnetic induction type of device actually works. Sensitivity and time resolution of force transducer was 50nN and 1ms respectively. Working displacement and time resolution of actuator as length transducer was 1-20 µm and 1.2 ms. We confirmed the performance of the device by showing appropriate force response to changes in length during myofibrils contraction, and possibility of application of the device to myofibril mechanics is discussed.

  12. Assessment of diesel contamination in groundwater using electromagnetic induction geophysical techniques

    SciTech Connect

    Jin, S.; Fallgren, P.; Cooper, J.; Morris, J; . Urynowicz, M.

    2008-07-01

    Determining hydrocarbon plumes in groundwater is typically accomplished through the installation of extensive monitoring wells. Issues of scale and site heterogeneities tend to introduce errors in delineating the extent of contamination and environmental impact. In this study, electromagnetic induction survey was investigated as an alternative technique for mapping petroleum contaminants in the subsurface. The surveys were conducted at a coal mining site near Gillette, Wyoming, using the EM34-XL ground conductivity meter. Data from this survey were validated with known concentrations of diesel compounds detected in groundwater from the study site. Groundwater data correlated well with the electromagnetic survey data, which was used to generate a site model to identify subsurface diesel plumes. To our knowledge, this is one of the first studies to use electromagnetic survey techniques for mapping hydrocarbon contamination in groundwater. Results from this study indicate that this geophysical technique can be an effective tool for assessing subsurface petroleum hydrocarbon sources and plumes at contaminated sites.

  13. Assessment of diesel contamination in groundwater using electromagnetic induction geophysical techniques.

    PubMed

    Jin, Song; Fallgren, Paul; Cooper, Jeffrey; Morris, Jeffrey; Urynowicz, Michael

    2008-05-01

    Determining hydrocarbon plumes in groundwater is typically accomplished through the installation of extensive monitoring wells. Issues of scale and site heterogeneities tend to introduce errors in delineating the extent of contamination and environmental impact. In this study, electromagnetic induction survey was investigated as an alternative technique for mapping petroleum contaminants in the subsurface. The surveys were conducted at a coal mining site near Gillette, Wyoming, using the EM34-XL ground conductivity meter. Data from this survey were validated with known concentrations of diesel compounds detected in groundwater from the study site. Groundwater data correlated well with the electromagnetic survey data, which was used to generate a site model to identify subsurface diesel plumes. To our knowledge, this is one of the first studies to use electromagnetic survey techniques for mapping hydrocarbon contamination in groundwater. Results from this study indicate that this geophysical technique can be an effective tool for assessing subsurface petroleum hydrocarbon sources and plumes at contaminated sites.

  14. A new source of lunar electromagnetic induction - Forcing by the diamagnetic cavity

    NASA Technical Reports Server (NTRS)

    Sonett, C. P.; Wiskerchen, M. J.

    1977-01-01

    Analysis of the power spectral densities (PSD's) of eight 50-hour time series from Apollo 12 lunar surface magnetometer (LSM) and isochronous Explorer 35 Ames magnetometer data points to the existence of a new source of electromagnetic induction in the interior of the moon which is independent of the transverse electric mode. This source is hypothesized to arise from extension of the cavity diamagnetic field into the moon in analogy with the fringing field of a solenoid.

  15. Footprint Size of a Helicopter-Borne Electromagnetic Induction Sounding System Versus Antenna Altitude

    DTIC Science & Technology

    1993-07-01

    Electromagnetic Induction Sounding System Versus Antenna Altitude Austin Kovacs, J . Scott Holladay and Clyde J. Bergeron, Jr. July 1993 Accesion For...prepared by Austin Kovacs Research Civil Engineer, U.S. Army Cold Regions Research and Engineering Laboratory; J . Scott Holladay, Geonex-Aerodat, Inc...Sounding N6845286MP6003 System Versus Antenna Altitude DTCG23-92-F-HNF062-2 6. AUTHORS Austin Kovacs, J . Scott Holladay and Clyde J. Bergeron, Jr. 7

  16. Magnetoacoustic Tomography with Magnetic Induction for Electrical Conductivity based Tissue imaging

    NASA Astrophysics Data System (ADS)

    Mariappan, Leo

    Electrical conductivity imaging of biological tissue has attracted considerable interest in recent years owing to research indicating that electrical properties, especially electrical conductivity and permittivity, are indicators of underlying physiological and pathological conditions in biological tissue. Also, the knowledge of electrical conductivity of biological tissue is of interest to researchers conducting electromagnetic source imaging and in design of devices that apply electromagnetic energy to the body such as MRI. So, the need for a non-invasive, high resolution impedance imaging method is highly desired. To address this need we have studied the magnetoacoustic tomography with magnetic induction (MAT-MI) method. In MAT-MI, the object is placed in a static and a dynamic magnetic field giving rise to ultrasound waves. The dynamic field induces eddy currents in the object, and the static field leads to generation of acoustic vibrations from Lorentz force on the induced currents. The acoustic vibrations are at the same frequency as the dynamic magnetic field, which is chosen to match the ultrasound frequency range. These ultrasound signals can be measured by ultrasound probes and are used to reconstruct MAT-MI acoustic source images using possible ultrasound imaging approaches .The reconstructed high spatial resolution image is indicative of the object's electrical conductivity contrast. We have investigated ultrasound imaging methods to reliably reconstruct the MAT-MI image under the practical conditions of limited bandwidth and transducer geometry. The corresponding imaging algorithm, computer simulation and experiments are developed to test the feasibility of these different methods. Also, in experiments, we have developed a system with the strong static field of an MRI magnet and a strong pulsed magnetic field to evaluate MAT-MI in biological tissue imaging. It can be seen from these simulations and experiments that conductivity boundary images with

  17. Electromagnetic induction heating of an orthopaedic nickel--titanium shape memory device.

    PubMed

    Müller, Christian W; Pfeifer, Ronny; El-Kashef, Tarek; Hurschler, Christof; Herzog, Dirk; Oszwald, Markus; Haasper, Carl; Krettek, Christian; Gösling, Thomas

    2010-12-01

    Shape memory orthopaedic implants made from nickel-titanium (NiTi) might allow the modulation of fracture healing, changing their cross-sectional shape by employing the shape memory effect. We aimed to show the feasibility and safety of contact-free electromagnetic induction heating of NiTi implants in a rat model. A water-cooled generator-oscillator combination was used. Induction characteristics were determined by measuring the temperature increase of a test sample in correlation to generator power and time. In 53 rats, NiTi implants were introduced into the right hind leg. The animals were transferred to the inductor, and the implant was electromagnetically heated to temperatures between 40 and 60°C. Blood samples were drawn before and 4 h after the procedure. IL-1, IL-4, IL-10, TNF-α, and IFN-γ were measured. Animals were euthanized at 3 weeks. Histological specimens from the hind leg and liver were retrieved and examined for inflammatory changes, necrosis, and corrosion pits. Cytokine measurements and histological specimens showed no significant differences among the groups. We concluded that electromagnetic induction heating of orthopedic NiTi implants is feasible and safe in a rat model. This is the first step in the development of new orthopedic implants in which stiffness or rigidity can be modified after implantation to optimize bone-healing.

  18. Investigation of electromagnetic induction retrievals of sea ice thickness using models and measurements

    NASA Astrophysics Data System (ADS)

    Samluk, Jesse Paul

    Using sea ice as a test material, this dissertation explores how electromagnetic responses interact with low-induction-number composite materials as a function of instrument footprint size and shape. This research combines several interdisciplinary topics including electrical engineering, materials science in composites, signal processing, and the geophysics of sea ice itself. Specifically, this work explores the development of new best practices that address consistency issues with electromagnetic induction instruments used on sea ice that employ electrical conductivity as a material property measurement. It does so by using two methods: modeling and measurements. For modeling, a three-dimensional, full-physics, heterogeneous model is used to investigate the electromagnetic field response of several sea ice cases. These cases include changing the material makeup of the sea ice, as well as using different transmitter locations and orientations, with the focus being how instrument footprint varies in each simulated case. For measurements, a co-calibration routine, among two physically different EM induction instruments in terms of instrument footprint, is developed and analyzed. Since these types of instruments are commonly used to measure conductivity in sea ice environments, historical calibration routines are only valid for one instrument at a time. The developed method presented herein provides a statistical solution for the material conductivities of both sea ice and seawater, as well as a solution for the actual ice thickness. These solutions are all based on field measurements made on sea ice during a data collection event held in Barrow, Alaska, in March 2013.

  19. Coil design considerations for a high-frequency electromagnetic induction sensing instrument

    NASA Astrophysics Data System (ADS)

    Sigman, John B.; Barrowes, Benjamin E.; Wang, Yinlin; Bennett, Hollis J.; Simms, Janet E.; Yule, Donald E.; O'Neill, Kevin; Shubitidze, Fridon

    2016-05-01

    Intermediate electrical conductivity (IEC) materials (101S/m < σ < 104S/m), such as carbon fiber (CF), have recently been used to make smart bombs. In addition, homemade improvised explosive devices (IED) can be produced with low conducting materials (10-4S/m < σ < 1S/m), such as Ammonium Nitrate (AN). To collect unexploded ordnance (UXO) from military training ranges and thwart deadly IEDs, the US military has urgent need for technology capable of detection and identification of subsurface IEC objects. Recent analytical and numerical studies have showed that these targets exhibit characteristic quadrature response peaks at high induction frequencies (100kHz - 15MHz, the High Frequency Electromagnetic Induction (HFEMI) band), and they are not detectable with traditional ultra wideband (UWB) electromagnetic induction (EMI) metal detectors operating between 100Hz - 100kHz. Using the HFEMI band for induction sensing is not so simple as driving existing instruments at higher frequencies, though. At low frequency, EMI systems use more wire turns in transmit and receive coils to boost signal-to-noise ratios (SNR), but at higher frequencies, the transmitter current has non-uniform distribution along the coil length. These non-uniform currents change the spatial distribution of the primary magnetic field and disturb axial symmetry and thwart established approaches for inferring subsurface metallic object properties. This paper discusses engineering tradeoffs for sensing with a broader band of frequencies ever used for EMI sensing, with particular focus on coil geometries.

  20. Electromagnetic compatibility and safety design of a patient compliance-free, inductive implant charger.

    PubMed

    Theodoridis, Michael P; Mollov, Stefan V

    2014-10-01

    This article presents the design of a domestic, radiofrequency induction charger for implants toward compliance with the Federal Communications Commission safety and electromagnetic compatibility regulations. The suggested arrangement does not impose any patient compliance requirements other than the use of a designated bed for night sleep, and therefore can find a domestic use. The method can be applied to a number of applications; a rechargeable pacemaker is considered as a case study. The presented work has proven that it is possible to realize a fully compliant inductive charging system with minimal patient interaction, and has generated important information for consideration by the designers of inductive charging systems. Experimental results have verified the validity of the theoretical findings.

  1. Transient electromagnetic behaviour in inductive oxygen and argon-oxygen plasmas

    NASA Astrophysics Data System (ADS)

    Chadwick, A. R.; Herdrich, G.; Kim, M.; Dally, B.

    2016-12-01

    In order to develop inductive electric propulsion as a flexible, throttleable technology for future space operations, a greater understanding of discharge transitions within the inductive plasma generator discharge chamber is required. This paper presents a non-intrusive method to determine the conditions under which transitions between the capacitive, low inductive, and high inductive regimes occur with greater accuracy, as well as determining the proportion of a single discharge cycle the plasma spends in either capacitive or inductive regime. Such a method allows a more robust method of classification of inductive discharges than previously available and can be applied to numerous gases. This approach presents an advantage over previous methods which relied on strongly radiating or thermally reactive gases to exhibit certain behaviour (due to the restriction of classical diagnostics on such high power sources) before a transition could be confirmed. This paper presents results from the proposed method applied to a pure oxygen plasma as well as two combinations of argon and oxygen (at 1:1 and 3:2 Ar:O2 volumetric ratios) in order to assess the tunability of electromagnetic regime transitions through modifications of gas composition rather than mechanical alterations. Transitions to the higher inductive mode were observed for much lower input powers for the argon-oxygen blends, as was expected, allowing final discharge conditions to occupy the inductive regime for 94% and 85% of a single discharge cycle for the 3:2 and 1:1 Ar:O2 mixtures, respectively. Pure oxygen achieved a maximum inductive proportion of 71% by comparison.

  2. The use of electromagnetic induction methods for establishing quantitative permafrost models in West Greenland

    NASA Astrophysics Data System (ADS)

    Ingeman-Nielsen, Thomas; Brandt, Inooraq

    2010-05-01

    The sedimentary settings at West Greenlandic town and infrastructural development sites are dominated by fine-grained marine deposits of late to post glacial origin. Prior to permafrost formation, these materials were leached by percolating precipitation, resulting in depletion of salts. Present day permafrost in these deposits is therefore very ice-rich with ice contents approaching 50-70% vol. in some areas. Such formations are of great concern in building and construction projects in Greenland, as they loose strength and bearing capacity upon thaw. It is therefore of both technical and economical interest to develop methods to precisely investigate and determine parameters such as ice-content and depth to bedrock in these areas. In terms of geophysical methods for near surface investigations, traditional methods such as Electrical Resistivity Tomography (ERT) and Refraction Seismics (RS) have generally been applied with success. The Georadar method usually fails due to very limited penetration depth in the fine-grained materials, and Electromagnetic Induction (EMI) methods are seldom applicable for quantitative interpretation due to the very high resistivities causing low induced currents and thus small secondary fields. Nevertheless, in some areas of Greenland the marine sequence was exposed relatively late, and as a result the sediments may not be completely leached of salts. In such cases, layers with pore water salinity approaching that of sea water, may be present below an upper layer of very ice rich permafrost. The saline pore water causes a freezing-point depression which results in technically unfrozen sediments at permafrost temperatures around -3 °C. Traditional ERT and VES measurements are severely affected by equivalency problems in these settings, practically prohibiting reasonable quantitative interpretation without constraining information. Such prior information may be obtained of course from boreholes, but equipment capable of drilling

  3. Theoretical and numerical approaches to the forward problem and sensitivity calculation of a novel contactless inductive flow tomography (CIFT)

    NASA Astrophysics Data System (ADS)

    Yin, W.; Peyton, A. J.; Stefani, F.; Gerbeth, G.

    2009-10-01

    A completely contactless flow measurement technique based on the principle of EM induction measurements—contactless inductive flow tomography (CIFT)—has been previously reported by a team based at Forschungszentrum Dresden-Rossendorf (FZD). This technique is suited to the measurement of velocity fields in high conductivity liquids, and the possible applications range from monitoring metal casting and silicon crystal growth in industry to gaining insights into the working of the geodynamo. The forward problem, i.e. calculating the induced magnetic field from a known velocity profile, can be described as a linear relationship when the magnetic Reynolds number is small. Previously, an integral equation method was used to formulate the forward problem; however, although the sensitivity matrices were calculated, they were not explicitly expressed and computation involved the solution of an ill-conditioned system of equations using a so-called deflation method. In this paper, we present the derivation of the sensitivity matrix directly from electromagnetic field theory and the results are expressed very concisely as the cross product of two field vectors. A numerical method based on a finite difference method has also been developed to verify the formulation. It is believed that this approach provides a simple yet fast route to the forward solution of CIFT. Furthermore, a method for sensor design selection based on eigenvalue analysis is presented.

  4. Induction ovens and electromagnetic interference: what is the risk for patients with implantable cardioverter defibrillators?

    PubMed

    Binggeli, Christian; Rickli, Hans; Ammann, Peter; Brunckhorst, Corinna; Hufschmid, Urs; Luechinger, Roger; Duru, Firat

    2005-04-01

    Electromagnetic fields may interfere with normal implantable cardioverter defibrillator (ICD) function. Although the devices are effectively shielded and use exclusively bipolar leads, electromagnetic interference (EMI) remains a concern when patients are exposed to several household appliances. The aim of this study was to evaluate potential EMI risk of induction ovens, which are increasingly common in private households. In vitro measurements of an induction oven for private households GK 43 TI (V-Zug, Inc., Zug, Switzerland) showed that heating is regulated by increasing operating time from level 1 (100 ms/sec) to 5 (continuous operation). From levels 5 to 9 the magnetic field increases. Nineteen patients with left-sided implants of single- and dual-chamber ICD systems (8 Medtronic, 7 Guidant, and 4 St. Jude Medical) (18 males, 1 female), age (mean +/- SEM) 58 +/- 3 years, were included in this study. All patients were examined in standing position, bent over the cooking pot (minimal distance to the induction coil 25 cm), and with the cooking pot put eccentrically over the induction field at three different cooking levels (level 2, 5, and 9). The tests were repeated touching the cooking pot with one hand. Ventricular sensitivity was left unchanged. Ventricular tachycardia therapies were turned off in Medtronic and Guidant devices and ventricular sensing was continuously monitored in St. Jude Medical devices during testing. Interrogation of the devices after exposure did not show any inappropriate tachycardia detection, oversensing, or reprogramming. In conclusion, ICD patients can be reassured that EMI is unlikely to affect their devices if induction ovens are used in their kitchens.

  5. Electromagnetic and Thermal-flow Modeling of a Cold-Wall Crucible Induction Melter

    SciTech Connect

    Fort, James A.; Garnich, Mark R.; Klymyshyn, Nicholas A.

    2005-02-01

    An approach for modeling cold-wall crucible induction melters is described. Materials in the melt and melter are non-ferromagnetic. In contrast to other modeling works reported in the literature, the numerical models utilize commercial codes. The ANSYS finite element code is employed for electromagnetic field simulations and the STAR-CD finite volume code for thermal-flow calculations. Results from the electromagnetic calculations in the form of local Joule heat and Lorentz force distributions are included as loads in the thermal-flow analysis. This loosely-coupled approach is made possible by the small variation in temperature and, consequently, small variation in electrical properties across the melt as well as the quasi-steady state nature of the thermal flow calculations. A three dimensional finite element grid for electromagnetic calculations is adapted to a similar axisymmetric finite volume grid for data transfer to the thermal-flow model. Results from the electromagnetic model compare well with operational data from a 175 mm diameter melter. Results from the thermal-flow simulation provide insight toward molten metal circulation patterns, temperature variations, and velocity magnitudes. Initial results are included for a model that simulates the formation of a solid (skull) layer on the crucible base and wall. Overall, the modeling approach is shown to produce useful results relating operational parameters to the physics of steady state melter operation.

  6. Using a PC and external media to quantitatively investigate electromagnetic induction

    NASA Astrophysics Data System (ADS)

    Bonanno, A.; Bozzo, G.; Camarca, M.; Sapia, P.

    2011-07-01

    In this article we describe an experimental learning path about electromagnetic induction which uses an Atwood machine where one of the two hanging bodies is a cylindrical magnet falling through a plexiglass guide, surrounded either by a coil or by a copper pipe. The first configuration (magnet falling across a coil) allows students to quantitatively study the Faraday-Neumann-Lenz law, while the second configuration (falling through a copper pipe) permits learners to investigate the complex phenomena of induction by quantifying the amount of electric power dissipated through the pipe as a result of Foucault eddy currents, when the magnet travels through the pipe. The magnet's fall acceleration can be set by adjusting the counterweight of the Atwood machine so that both the kinematic quantities associated with it and the electromotive force induced within the coil are continuously and quantitatively monitored (respectively, by a common personal computer (PC) equipped with a webcam and by freely available software that makes it possible to use the audio card to convert the PC into an oscilloscope). Measurements carried out when the various experimental parameters are changed provide a useful framework for a thorough understanding and clarification of the conceptual nodes related to electromagnetic induction. The proposed learning path is under evaluation in various high schools participating in the project 'Lauree Scientifiche' promoted by the Italian Department of Education.

  7. Electromagnetic Induction

    ERIC Educational Resources Information Center

    Yochum, Hank; Vinion-Dubiel, Arlene; Granger, Jill; Lindsay, Lynne; Maass, Teresa; Mayhew, Sarah

    2013-01-01

    Engaging children in authentic investigation opens the doors for them to gain deep conceptual understanding in science. As students engage in investigation, they experience the practices employed by scientists and engineers, as highlighted in the Next Generation Science Standards (Achieve Inc. 2013). They also begin to understand the nature of…

  8. The minimization of the extraneous electromagnetic fields of an inductive power transfer system

    NASA Astrophysics Data System (ADS)

    McLean, James; Sutton, Robert

    2013-04-01

    The efficiency of inductive wireless power transfer (IPT) systems has been extensively studied. However, the electromagnetic compatibility of such systems is at least as important as the efficiency and has received much less attention. We consider the net magnetic dipole moment of the system as a figure of merit. That is, we seek to minimize the magnitude of the net dipole moment in order to minimize both the near magnetic fields and the radiated power. A 20 kHz, 3.3 kW, IPT system, representative of typical wireless vehicular battery charging systems, is considered and it is seen that one particular value of load impedance minimizes the net dipole moment while another, distinct, value maximizes efficiency. Thus, efficiency must be traded off, at least to some extent, in order to minimize extraneous electromagnetic fields.

  9. Summary of sensor evaluation for the Fusion ELectromagnetic Induction eXperiment (FELIX)

    SciTech Connect

    Knott, M.J.

    1982-08-01

    As part of the First Wall/Blanket/Shield Engineering Test Program, a test bed called FELIX (Fusion ELectromagnetic Induction eXperiment) is now under construction at ANL. Its purpose will be to test, evaluate, and develop computer codes for the prediction of electromagnetically induced phenomenon in a magnetic environment modeling that of a fusion reaction. Crucial to this process is the sensing and recording of the various induced effects. Sensor evaluation for FELIX has reached the point where most sensor types have been evaluated and preliminary decisions are being made as to type and quantity for the initial FELIX experiments. These early experiments, the first, flat plate experiment in particular, will be aimed at testing the sensors as well as the pertinent theories involved. The reason for these evaluations, decisions, and proof tests is the harsh electrical and magnetic environment that FELIX presents.

  10. Vertical spatial sensitivity and exploration depth of low-induction-number electromagnetic-induction instruments

    USGS Publications Warehouse

    Callegary, J.B.; Ferre, T. P. A.; Groom, R.W.

    2007-01-01

    Vertical spatial sensitivity and effective depth of exploration (d e) of low-induction-number (LIN) instruments over a layered soil were evaluated using a complete numerical solution to Maxwell's equations. Previous studies using approximate mathematical solutions predicted a vertical spatial sensitivity for instruments operating under LIN conditions that, for a given transmitter-receiver coil separation (s), coil orientation, and transmitter frequency, should depend solely on depth below the land surface. When not operating under LIN conditions, vertical spatial sensitivity and de also depend on apparent soil electrical conductivity (??a) and therefore the induction number (??). In this new evaluation, we determined the range of ??a and ?? values for which the LIN conditions hold and how de changes when they do not. Two-layer soil models were simulated with both horizontal (HCP) and vertical (VCP) coplanar coil orientations. Soil layers were given electrical conductivity values ranging from 0.1 to 200 mS m-1. As expected, de decreased as ??a increased. Only the least electrically conductive soil produced the de expected when operating under LIN conditions. For the VCP orientation, this was 1.6s, decreasing to 0.8s in the most electrically conductive soil. For the HCP orientation, de decreased from 0.76s to 0.51s. Differences between this and previous studies are attributed to inadequate representation of skin-depth effect and scattering at interfaces between layers. When using LIN instruments to identify depth to water tables, interfaces between soil layers, and variations in salt or moisture content, it is important to consider the dependence of de on ??a. ?? Soil Science Society of America.

  11. Electromagnetic induction pump for pumping liquid metals and other conductive liquids

    DOEpatents

    Smither, Robert K.

    1993-01-01

    An electromagnetic induction pump in which an electrically conductive liquid is made to flow by means of a force created by interaction of a permanent magnetic field and a DC current. The pump achieves high efficiency through combination of: powerful permanent magnet materials which provide a high strength field that is uniform and constant; steel tubing formed into a coil which is constructed to carry conducting liquids with minimal electrical resistance and heat; and application of a voltage to induce a DC current which continuously produces a force in the direction of the desired flow.

  12. Electromagnetic induction pump for pumping liquid metals and other conductive liquids

    DOEpatents

    Smither, R.K.

    1993-05-11

    An electromagnetic induction pump is described in which an electrically conductive liquid is made to flow by means of a force created by interaction of a permanent magnetic field and a DC current. The pump achieves high efficiency through combination of: powerful permanent magnet materials which provide a high strength field that is uniform and constant; steel tubing formed into a coil which is constructed to carry conducting liquids with minimal electrical resistance and heat; and application of a voltage to induce a DC current which continuously produces a force in the direction of the desired flow.

  13. Millimeter-wave imaging with slab focusing lens made of electromagnetic-induction materials.

    PubMed

    Yang, Kui; Wang, Jinbang; Zhao, Lu; Liu, Zhiguo; Zhang, Tao

    2016-01-11

    A slab focusing lens in this work has been designed, which consists of electromagnetic-induction materials (cage-shaped granules of conductor materials) and polymethyl methacrylate (PMMA) materials. A compound lens with a thickness of 32 mm is composed of two slab focusing lenses, and has a refractive index of 1.41 at 35 GHz. Millimeter-wave (MMW) images of metallic objects have been obtained with the compound lens. The image quality has been compared by means of the compound lens and the polyethylene lens. The experimental results show good feasibility of the compound lens in MMW imaging.

  14. Emergent Electromagnetic Induction and Adiabatic Charge Pumping in Noncentrosymmetric Weyl Semimetals

    NASA Astrophysics Data System (ADS)

    Ishizuka, Hiroaki; Hayata, Tomoya; Ueda, Masahito; Nagaosa, Naoto

    2016-11-01

    The photovoltaic effect due to the adiabatic quantum phase in noncentrosymmetric Weyl semimetals is studied. We particularly focus on the case in which an external ac electric field is applied. By considering a generalized Weyl Hamiltonian with nonlinear terms, we show that the photocurrent is induced by circularly, rather than linearly, polarized light. This photovoltaic current can be understood as an emergent electromagnetic induction in momentum space; the Weyl node is a magnetic monopole in momentum space, the circular motion of which induces the electric field. This result is distinct from conventional photovoltaic effects, and the estimated photocurrent is ˜10-1- 101 nA , which can be detected experimentally.

  15. Electromagnetic induction by finite wavenumber source fields in 2-D lateral heterogeneities - The transverse electric mode

    NASA Technical Reports Server (NTRS)

    Hermance, J. F.

    1984-01-01

    Electromagnetic induction in a laterally homogeneous earth is analyzed in terms of a source field with finite dimensions. Attention is focused on a time-varying two-dimensional current source directed parallel to the strike of a two-dimensional anomalous structure within the earth, i.e., the E-parallel mode. The spatially harmonic source field is expressed as discontinuities in the magnetic (or electric) field of the current in the source. The model is applied to describing the magnetic gradients across megatectonic features, and may be used to predict the magnetic fields encountered by a satellite orbiting above the ionosphere.

  16. Analytical modelling of soil effects on electromagnetic induction sensor for humanitarian demining

    NASA Astrophysics Data System (ADS)

    Vasić, D.; Ambruš, D.; Bilas, V.

    2013-06-01

    Accurate compensation of the soil effect is essential for a new generation of sensitive classification-based electromagnetic induction landmine detectors. We present an analytical model for evaluation of the soil effect suitable for straightforward numerical implementation. The modelled soil consists of arbitrary number of conductive and magnetic layers. The solution region is truncated leading to the solution in form of a series rather than infinite integrals. Frequency-dependent permeability is inherent to the model, and time domain analysis can be made using DFT. In order to illustrate the model usage, we evaluate performances of three metal detector designs.

  17. Electromagnetic field distribution calculation in solenoidal inductively coupled plasma using finite difference method

    SciTech Connect

    Li, W. P.; Liu, Y.; Long, Q.; Chen, D. H.; Chen, Y. M.

    2008-10-15

    The electromagnetic field (both E and B fields) is calculated for a solenoidal inductively coupled plasma (ICP) discharge. The model is based on two-dimensional cylindrical coordinates, and the finite difference method is used for solving Maxwell equations in both the radial and axial directions. Through one-turn coil measurements, assuming that the electrical conductivity has a constant value in each cross section of the discharge tube, the calculated E and B fields rise sharply near the tube wall. The nonuniform radial distributions imply that the skin effect plays a significant role in the energy balance of the stable ICP. Damped distributions in the axial direction show that the magnetic flux gradually dissipates into the surrounding space. A finite difference calculation allows prediction of the electrical conductivity and plasma permeability, and the induction coil voltage and plasma current can be calculated, which are verified for correctness.

  18. Electromagnetic induction imaging of concealed metallic objects by means of resonating circuits

    NASA Astrophysics Data System (ADS)

    Guilizzoni, R.; Watson, J. C.; Bartlett, P. A.; Renzoni, F.

    2016-05-01

    An electromagnetic induction system, suitable for 2D imaging of metallic samples of different electrical conductivities, has been developed. The system is based on a parallel LCR circuit comprising a ferrite-cored coil (7.8 mm x 9.5 mm, L=680 μH at 1 KHz), a variable resistor and capacitor. The working principle of the system is based on eddy current induction inside a metallic sample when this is introduced into the AC magnetic field created by the coil. The inductance of the LCR circuit is modified due to the presence of the sample, to an extent that depends on its conductivity. Such modification is known to increase when the system is operated at its resonant frequency. Characterizing different metals based on their values of conductivity is therefore possible by utilizing a suitable system operated at resonance. Both imaging and material characterization were demonstrated by means of the proposed electromagnetic induction technique. Furthermore, the choice of using a system with an adjustable resonant frequency made it possible to select resonances that allow magnetic-field penetration through conductive screens. Investigations on the possibility of imaging concealed metals by penetrating such shields have been carried out. A penetration depth of δ~3 mm through aluminium (Al) was achieved. This allowed concealed metallic samples- having conductivities ranging from 0.54 to 59.77 MSm-1 and hidden behind 1.5-mm-thick Al shields- to be imaged. Our results demonstrate that the presence of the concealed metallic objects can be revealed. The technique was thus shown to be a promising detection tool for security applications.

  19. Magnetic induction tomography using an all-optical ⁸⁷Rb atomic magnetometer.

    PubMed

    Wickenbrock, Arne; Jurgilas, Sarunas; Dow, Albert; Marmugi, Luca; Renzoni, Ferruccio

    2014-11-15

    We demonstrate magnetic induction tomography (MIT) with an all-optical atomic magnetometer. Our instrument creates a conductivity map of conductive objects. Both the shape and size of the imaged samples compare very well with the actual shape and size. Given the potential of all-optical atomic magnetometers for miniaturization and extreme sensitivity, the proof-of-principle presented in this Letter opens up promising avenues in the development of instrumentation for MIT.

  20. The application of magnetic gradiometry and electromagnetic induction at a former radioactive waste disposal site.

    PubMed

    Rucker, Dale Franklin

    2010-04-01

    A former radioactive waste disposal site is surveyed with two non-intrusive geophysical techniques, including magnetic gradiometry and electromagnetic induction. Data were gathered over the site by towing the geophysical equipment mounted to a non-electrically conductive and non-magnetic fibre-glass cart. Magnetic gradiometry, which detects the location of ferromagnetic material, including iron and steel, was used to map the existence of a previously unknown buried pipeline formerly used in the delivery of liquid waste to a number of surface disposal trenches and concrete vaults. The existence of a possible pipeline is reinforced by historical engineering drawing and photographs. The electromagnetic induction (EMI) technique was used to map areas of high and low electrical conductivity, which coincide with the magnetic gradiometry data. The EMI also provided information on areas of high electrical conductivity unrelated to a pipeline network. Both data sets demonstrate the usefulness of surface geophysical surveillance techniques to minimize the risk of exposure in the event of future remediation efforts.

  1. A differential electromagnetic induction torque sensor and its finite element analysis.

    PubMed

    Hao, Zhao

    2015-05-01

    Torque is an important parameter for condition monitoring and fault diagnosis for rotary machines. This paper describes a new structure differential torque sensor based on the principle of electromagnetic induction. The method involves the construction of a pulsating flux by the excitation winding of the sensor, and the torsion angle produced by the load torque is converted into the angle displacements of the excitation winding and the output winding. Last, the output winding of sensor generates an induction potential force, which is proportional to the load torque as seen through electromagnetic coupling. Sensor sensitivity would be reduced by load effect; therefore, this paper presents a suppression method that can ensure the sensitivity is not affected. The transfer function of the sensor is constructed through Laplace transformation. The sensor characteristics are simulated by finite elements, including the influence of winding coil numbers and excitation voltage frequency. The sensor was calibrated by a torsion testing machine, and the experimental results indicated that the sensitivity of the sensor is about 18.2 mV/Nm, the non-repeatability error is about 2.3%, the non-linear error is about 3.3%, and the hysteresis error is about 2.6%.

  2. University students’ understanding of the electromotive force concept in the context of electromagnetic induction

    NASA Astrophysics Data System (ADS)

    Zuza, Kristina; De Cock, Mieke; van Kampen, Paul; Bollen, Laurens; Guisasola, Jenaro

    2016-11-01

    In this work, we present research on university students’ understanding of the concept of electromotive force (emf). The work presented here is a continuation of previous research by Garzón et al (2014 Am. J. Phys. 82 72-6) in which university students’ understanding of emf in the contexts of transient current and direct current circuits was analyzed. In the work we present here the investigation focuses on electromagnetic induction phenomena. Three open-ended questions from a broader questionnaire were analyzed in depth. We used phenomenography to define categories and detect lines of reasoning and difficulties in conceptual understanding. Very few students showed a good understanding of the emf concept in electromagnetic induction circuits or an ability to distinguish it from potential difference. Although the prevalences of the responses in the different categories are different, we find that the difficulties are the same in the three universities. Standard instruction does not allow most students to analyze unfamiliar contexts where the answer requires a systemic explanatory model.

  3. Three-dimensional sensitivity distribution and sample volume of low-induction-number electromagnetic-induction instruments

    USGS Publications Warehouse

    Callegary, J.B.; Ferre, T. P. A.; Groom, R.W.

    2012-01-01

    There is an ongoing effort to improve the understanding of the correlation of soil properties with apparent soil electrical conductivity as measured by low-induction-number electromagnetic-induction (LIN FEM) instruments. At a minimum, the dimensions of LIN FEM instruments' sample volume, the spatial distribution of sensitivity within that volume, and implications for surveying and analyses must be clearly defined and discussed. Therefore, a series of numerical simulations was done in which a conductive perturbation was moved systematically through homogeneous soil to elucidate the three-dimensional sample volume of LIN FEM instruments. For a small perturbation with electrical conductivity similar to that of the soil, instrument response is a measure of local sensitivity (LS). Our results indicate that LS depends strongly on the orientation of the instrument's transmitter and receiver coils and includes regions of both positive and negative LS. Integration of the absolute value of LS from highest to lowest was used to contour cumulative sensitivity (CS). The 90% CS contour was used to define the sample volume. For both horizontal and vertical coplanar coil orientations, the longest dimension of the sample volume was at the surface along the main instrument axis with a length of about four times the intercoil spacing (s) with maximum thicknesses of about 1 and 0.3 s, respectively. The imaged distribution of spatial sensitivity within the sample volume is highly complex and should be considered in conjunction with the expected scale of heterogeneity before the use and interpretation of LIN FEM for mapping and profiling. ?? Soil Science Society of America.

  4. Mapping soil water dynamics and a moving wetting front by spatiotemporal inversion of electromagnetic induction data

    NASA Astrophysics Data System (ADS)

    Huang, J.; Monteiro Santos, F. A.; Triantafilis, J.

    2016-11-01

    Characterization of the spatiotemporal distribution of soil volumetric water content (θ) is fundamental to agriculture, ecology, and earth science. Given the labor intensive and inefficient nature of determining θ, apparent electrical conductivity (ECa) measured by electromagnetic induction has been used as a proxy. A number of previous studies have employed inversion algorithms to convert ECa data to depth-specific electrical conductivity (σ) which could then be correlated to soil θ and other soil properties. The purpose of this study was to develop a spatiotemporal inversion algorithm which accounts for the temporal continuity of ECa. The algorithm was applied to a case study where time-lapse ECa was collected on a 350 m transect on seven different days on an alfalfa farm in the USA. Results showed that the approach was able to map the location of moving wetting front along the transect. Results also showed that the spatiotemporal inversion algorithm was more precise (RMSE = 0.0457 cm3/cm3) and less biased (ME = -0.0023 cm3/cm3) as compared with the nonspatiotemporal inversion approach (0.0483 cm3/cm3 and ME = -0.0030 cm3/cm3, respectively). In addition, the spatiotemporal inversion algorithm allows for a reduced set of ECa surveys to be used when non abrupt changes of soil water content occur with time. To apply this spatiotemporal inversion algorithm beyond low induction number condition, full solution of the EM induction phenomena can be studied in the future.

  5. Spatial relationship between the productivity of cane sugar and soil electrical conductivity measured by electromagnetic induction

    NASA Astrophysics Data System (ADS)

    Siqueira, Glecio; Silva, Jucicléia; Bezerra, Joel; Silva, Enio; Montenegro, Abelardo

    2013-04-01

    The cultivation of sugar cane in Brazil occupies a prominent place in national production chain, because the country is the main world producer of sugar and ethanol. Accordingly, studies are needed that allow an integrated production and technified, and especially that estimates of crops are consistent with the actual production of each region. The objective of this study was to determine the spatial relationship between the productivity of cane sugar and soil electrical conductivity measured by electromagnetic induction. The field experiment was conducted at an agricultural research site located in Goiana municipality, Pernambuco State, north-east of Brazil (Latitude 07 ° 34 '25 "S, Longitude 34 ° 55' 39" W). The surface of the studied field is 6.5 ha, and its mean height 8.5 m a.s.l. This site has been under sugarcane (Saccharum officinarum sp.) monoculture during the last 24 years and it was managed burning the straw each year after harvesting, renewal of plantation was performed every 7 years. Studied the field is located 10 km east from Atlantic Ocean and it is representative of the regional landscape lowlands, whose soils are affected by salinity seawater, sugarcane plantations with the main economical activity. Soil was classified an orthic the Podsol. The productivity of cane sugar and electrical conductivity were measured in 90 sampling points. The productivity of cane sugar was determined in each of the sampling points in plots of 9 m2. The Apparent soil electrical conductivity (ECa, mS m-1) was measured with an electromagnetic induction device EM38-DD (Geonics Limited). The equipment consists of two units of measurement, one in a horizontal dipole (ECa-H) to provide effective measurement distance of 1.5 m approximately and other one in vertical dipole (ECa-V) with an effective measurement depth of approximately 0.75 m. Data were analyzed using descriptive statistics and geostatistical tools. The results showed that productivity in the study area

  6. The 3-D reconstruction of medieval wetland reclamation through electromagnetic induction survey

    PubMed Central

    De Smedt, Philippe; Van Meirvenne, Marc; Herremans, Davy; De Reu, Jeroen; Saey, Timothy; Meerschman, Eef; Crombé, Philippe; De Clercq, Wim

    2013-01-01

    Studies of past human-landscape interactions rely upon the integration of archaeological, biological and geological information within their geographical context. However, detecting the often ephemeral traces of human activities at a landscape scale remains difficult with conventional archaeological field survey. Geophysical methods offer a solution by bridging the gap between point finds and the surrounding landscape, but these surveys often solely target archaeological features. Here we show how simultaneous mapping of multiple physical soil properties with a high resolution multi-receiver electromagnetic induction (EMI) survey permits a reconstruction of the three-dimensional layout and pedological setting of a medieval reclaimed landscape in Flanders (Belgium). Combined with limited and directed excavations, the results offer a unique insight into the way such marginal landscapes were reclaimed and occupied during the Middle Ages. This approach provides a robust foundation for unravelling complex historical landscapes and will enhance our understanding of past human-landscape interactions. PMID:23519060

  7. The 3-D reconstruction of medieval wetland reclamation through electromagnetic induction survey.

    PubMed

    De Smedt, Philippe; Van Meirvenne, Marc; Herremans, Davy; De Reu, Jeroen; Saey, Timothy; Meerschman, Eef; Crombé, Philippe; De Clercq, Wim

    2013-01-01

    Studies of past human-landscape interactions rely upon the integration of archaeological, biological and geological information within their geographical context. However, detecting the often ephemeral traces of human activities at a landscape scale remains difficult with conventional archaeological field survey. Geophysical methods offer a solution by bridging the gap between point finds and the surrounding landscape, but these surveys often solely target archaeological features. Here we show how simultaneous mapping of multiple physical soil properties with a high resolution multi-receiver electromagnetic induction (EMI) survey permits a reconstruction of the three-dimensional layout and pedological setting of a medieval reclaimed landscape in Flanders (Belgium). Combined with limited and directed excavations, the results offer a unique insight into the way such marginal landscapes were reclaimed and occupied during the Middle Ages. This approach provides a robust foundation for unravelling complex historical landscapes and will enhance our understanding of past human-landscape interactions.

  8. Emergent Electromagnetic Induction and Adiabatic Charge Pumping in Noncentrosymmetric Weyl Semimetals.

    PubMed

    Ishizuka, Hiroaki; Hayata, Tomoya; Ueda, Masahito; Nagaosa, Naoto

    2016-11-18

    The photovoltaic effect due to the adiabatic quantum phase in noncentrosymmetric Weyl semimetals is studied. We particularly focus on the case in which an external ac electric field is applied. By considering a generalized Weyl Hamiltonian with nonlinear terms, we show that the photocurrent is induced by circularly, rather than linearly, polarized light. This photovoltaic current can be understood as an emergent electromagnetic induction in momentum space; the Weyl node is a magnetic monopole in momentum space, the circular motion of which induces the electric field. This result is distinct from conventional photovoltaic effects, and the estimated photocurrent is ∼10^{-1}-10^{1}  nA, which can be detected experimentally.

  9. Electromagnetic induction between axons and their schwann cell myelin-protein sheaths.

    PubMed

    Goodman, G; Bercovich, D

    2013-12-01

    Two concepts have long dominated vertebrate nerve electrophysiology: (a) Schwann cell-formed myelin sheaths separated by minute non-myelinated nodal gaps and spiraling around axons of peripheral motor nerves reduce current leakage during propagation of trains of axon action potentials; (b) "jumping" by action potentials between successive nodes greatly increases signal conduction velocity. Long-held and more recent assumptions and issues underlying those concepts have been obscured by research emphasis on axon-sheath biochemical symbiosis and nerve regeneration. We hypothesize: mutual electromagnetic induction in the axon-glial sheath association, is fundamental in signal conduction in peripheral and central myelinated axons, explains the g-ratio and is relevant to animal navigation.

  10. Urban soil exploration through multi-receiver electromagnetic induction and stepped-frequency ground penetrating radar.

    PubMed

    Van De Vijver, Ellen; Van Meirvenne, Marc; Vandenhaute, Laura; Delefortrie, Samuël; De Smedt, Philippe; Saey, Timothy; Seuntjens, Piet

    2015-07-01

    In environmental assessments, the characterization of urban soils relies heavily on invasive investigation, which is often insufficient to capture their full spatial heterogeneity. Non-invasive geophysical techniques enable rapid collection of high-resolution data and provide a cost-effective alternative to investigate soil in a spatially comprehensive way. This paper presents the results of combining multi-receiver electromagnetic induction and stepped-frequency ground penetrating radar to characterize a former garage site contaminated with petroleum hydrocarbons. The sensor combination showed the ability to identify and accurately locate building remains and a high-density soil layer, thus demonstrating the high potential to investigate anthropogenic disturbances of physical nature. In addition, a correspondence was found between an area of lower electrical conductivity and elevated concentrations of petroleum hydrocarbons, suggesting the potential to detect specific chemical disturbances. We conclude that the sensor combination provides valuable information for preliminary assessment of urban soils.

  11. Improved electromagnetic induction processing with novel adaptive matched filter and matched subspace detection

    NASA Astrophysics Data System (ADS)

    Hayes, Charles E.; McClellan, James H.; Scott, Waymond R.; Kerr, Andrew J.

    2016-05-01

    This work introduces two advances in wide-band electromagnetic induction (EMI) processing: a novel adaptive matched filter (AMF) and matched subspace detection methods. Both advances make use of recent work with a subspace SVD approach to separating the signal, soil, and noise subspaces of the frequency measurements The proposed AMF provides a direct approach to removing the EMI self-response while improving the signal to noise ratio of the data. Unlike previous EMI adaptive downtrack filters, this new filter will not erroneously optimize the EMI soil response instead of the EMI target response because these two responses are projected into separate frequency subspaces. The EMI detection methods in this work elaborate on how the signal and noise subspaces in the frequency measurements are ideal for creating the matched subspace detection (MSD) and constant false alarm rate matched subspace detection (CFAR) metrics developed by Scharf The CFAR detection metric has been shown to be the uniformly most powerful invariant detector.

  12. Rapid position estimation using electromagnetic induction data from the MetalMapper in dynamic mode

    NASA Astrophysics Data System (ADS)

    Grzegorczyk, Tomasz M.; Barrowes, Benjamin; George, David; Shubitidze, Fridon; Fernández, J. P.; O'Neill, Kevin

    2011-06-01

    Dynamic data from the MetalMapper electromagnetic induction sensor are analyzed using a fast inversion algorithm in order to obtain position information of buried anomalies. After validating the algorithm by comparing static and dynamic inversions from reference measurements at Camp San Luis Obispo, the algorithm is applied to realistic dynamic measurements from Camp Butner. A sequence of 939 data points are inverted as the MetalMapper travels along a calibration lane, flagging a few positions as corresponding to buried anomalies. An a posteriori comparison with field plots reveals a good agreement between the flagged positions and the field peak values, suggesting the efficacy of the algorithm at detecting a large variety of anomalies from dynamic data.

  13. Using electromagnetic induction technology to predict volatile fatty acid, source area differences.

    PubMed

    Woodbury, Bryan L; Eigenberg, Roger A; Varel, Vince; Lesch, Scott; Spiehs, Mindy J

    2011-01-01

    Subsurface measures have been adapted to identify manure accumulation on feedlot surfaces. Understanding where manure accumulates can be useful to develop management practices that mitigate air emissions from manure, such as odor or greenhouse gases. Objectives were to determine if electromagnetic induction could be used to predict differences in volatile fatty acids (VFA) and other volatiles produced in vitro from feedlot surface material following a simulated rain event. Twenty soil samples per pen were collected from eight pens with cattle fed two different diets using a predictive sampling approach. These samples were incubated at room temperature for 3 d to determine fermentation products formed. Fermentation products were categorized into acetate, straight-, branched-chained, and total VFAs. These data were used to develop calibration prediction models on the basis of properties measured by electromagnetic induction (EMI). Diet had no significant effect on mean volatile solids (VS) concentration of accumulated manure. However, manure from cattle fed a corn (Zea mays L.)-based diet had significantly ( P ≤ 0.1) greater mean straight-chained and total VFA generation than pens where wet distillers grain with solubles (WDGS) were fed. Alternately, pens with cattle fed a WDGS-based diet had significantly (P ≤ 0.05) greater branched-chained VFAs than pens with cattle fed a corn-based diet. Many branched-chain VFAs have a lower odor threshold than straight-chained VFAs; therefore, emissions from WDGS-based diet manure would probably have a lower odor threshold. We concluded that diets can affect the types and quantities of VFAs produced following a rain event. Understanding odorant accumulation patterns and the ability to predict generation can be used to develop precision management practices to mitigate odor emissions.

  14. Hybridizing triboelectrification and electromagnetic induction effects for high-efficient mechanical energy harvesting.

    PubMed

    Hu, Youfan; Yang, Jin; Niu, Simiao; Wu, Wenzhuo; Wang, Zhong Lin

    2014-07-22

    The recently introduced triboelectric nanogenerator (TENG) and the traditional electromagnetic induction generator (EMIG) are coherently integrated in one structure for energy harvesting and vibration sensing/isolation. The suspended structure is based on two oppositely oriented magnets that are enclosed by hollow cubes surrounded with coils, which oscillates in response to external disturbance and harvests mechanical energy simultaneously from triboelectrification and electromagnetic induction. It extends the previous definition of hybrid cell to harvest the same type of energy with multiple approaches. Both the sliding-mode TENG and contact-mode TENG can be achieved in the same structure. In order to make the TENG and EMIG work together, transformers are used to match the output impedance between these two power sources with very different characteristics. The maximum output power of 7.7 and 1.9 mW on the same load of 5 kΩ was obtained for the TENG and EMIG, respectively, after impedance matching. Benefiting from the rational design, the output signal from the TENG and the EMIG are in phase. They can be added up directly to get an output voltage of 4.6 V and an output current of 2.2 mA in parallel connection. A power management circuit was connected to the hybrid cell, and a regulated voltage of 3.3 V with constant current was achieved. For the first time, a logic operation was carried out on a half-adder circuit by using the hybrid cell working as both the power source and the input digit signals. We also demonstrated that the hybrid cell can serve as a vibration isolator. Further applications as vibration dampers, triggers, and sensors are all promising.

  15. Promoting Conceptual Development in Physics Teacher Education: Cognitive-Historical Reconstruction of Electromagnetic Induction Law

    NASA Astrophysics Data System (ADS)

    Mäntylä, Terhi

    2013-06-01

    In teaching physics, the history of physics offers fruitful starting points for designing instruction. I introduce here an approach that uses historical cognitive processes to enhance the conceptual development of pre-service physics teachers' knowledge. It applies a method called cognitive-historical approach, introduced to the cognitive sciences by Nersessian (Cognitive Models of Science. University of Minnesota Press, Minneapolis, pp. 3-45, 1992). The approach combines the analyses of actual scientific practices in the history of science with the analytical tools and theories of contemporary cognitive sciences in order to produce knowledge of how conceptual structures are constructed and changed in science. Hence, the cognitive-historical analysis indirectly produces knowledge about the human cognition. Here, a way to use the cognitive-historical approach for didactical purposes is introduced. In this application, the cognitive processes in the history of physics are combined with current physics knowledge in order to create a cognitive-historical reconstruction of a certain quantity or law for the needs of physics teacher education. A principal aim of developing the approach has been that pre-service physics teachers must know how the physical concepts and laws are or can be formed and justified. As a practical example of the developed approach, a cognitive-historical reconstruction of the electromagnetic induction law was produced. For evaluating the uses of the cognitive-historical reconstruction, a teaching sequence for pre-service physics teachers was conducted. The initial and final reports of twenty-four students were analyzed through a qualitative categorization of students' justifications of knowledge. The results show a conceptual development in the students' explanations and justifications of how the electromagnetic induction law can be formed.

  16. The Electrical Activity of Neurons Subject to Electromagnetic Induction and Gaussian White Noise

    NASA Astrophysics Data System (ADS)

    Wang, Ya; Ma, Jun; Xu, Ying; Wu, Fuqiang; Zhou, Ping

    Neurons can give appropriate response to external electrical stimuli and the modes in electrical activities can be carefully selected. Most of the neuron models mainly emphasize on the ion channel currents embedded into the membrane and the properties in electrical activities can be produced in the theoretical models. Indeed, some physical effect should be considered during the model setting for neuronal activities. In fact, induced current and the electrical field will cause the membrane potential to change and an exchange of charged ions during the fluctuation of ion concentration in cell. As a result, the effect of electromagnetic induction should be seriously considered. In this paper, magnetic flux is proposed to describe the effect of electromagnetic field, and the memristor is used to realize coupling on membrane by inputting induced current based on consensus of physical unit. Noise is also considered to detect the dynamical response in electrical activities and stochastic resonance, it is found that multiple modes can be selected in the electrical activities and it could be associated with memory effect and self-adaption in neurons.

  17. Physics Almost Saved the President! Electromagnetic Induction and the Assassination of James Garfield: A Teaching Opportunity in Introductory Physics

    ERIC Educational Resources Information Center

    Overduin, James; Molloy, Dana; Selway, Jim

    2014-01-01

    Electromagnetic induction is probably one of the most challenging subjects for students in the introductory physics sequence, especially in algebra-based courses. Yet it is at the heart of many of the devices we rely on today. To help students grasp and retain the concept, we have put together a simple and dramatic classroom demonstration that…

  18. Myocardial function improved by electromagnetic field induction of stress protein hsp70.

    PubMed

    George, Isaac; Geddis, Matthew S; Lill, Zachary; Lin, Hana; Gomez, Teodoro; Blank, Martin; Oz, Mehmet C; Goodman, Reba

    2008-09-01

    Studies on myocardial function have shown that hsp70, stimulated by an increase in temperature, leads to improved survival following ischemia-reperfusion (I-R). Low frequency electromagnetic fields (EMFs) also induce the stress protein hsp70, but without elevating temperature. We have examined the hemodynamic changes in concert with EMF pre-conditioning and the induction of hsp70 to determine whether improved myocardial function occurs following I-R injury in Sprague-Dawley rats. Animals were exposed to EMF (60 Hz, 8 microT) for 30 min prior to I-R. Ischemia was then induced by ligation of left anterior descending coronary artery (LAD) for 30 min, followed by 30 min of reperfusion. Blood and heart tissue levels for hsp70 were determined by Western blot and RNA transcription by rtPCR. Significant upregulation of the HSP70 gene and increased hsp70 levels were measured in response to EMF pre-exposures. Invasive hemodynamics, as measured using a volume conductance catheter, demonstrated significant recovery of systolic contractile function after 30 min of reperfusion following EMF exposure. Additionally, isovolemic relaxation, a measure of ventricular diastolic function, was markedly improved in EMF-treated animals. In conclusion, non-invasive EMF induction of hsp70 preserved myocardial function and has the potential to improve tolerance to ischemic injury.

  19. The detection of brain oedema with frequency-dependent phase shift electromagnetic induction.

    PubMed

    González, César A; Rubinsky, Boris

    2006-06-01

    The spectroscopic distribution of inductive phase shift in the brain as a function of the relative volume of oedema was evaluated with theoretical and experimental methods in the frequency range 1 to 8 MHz. The theoretical study employed a simple mathematical model of electromagnetic induction in tissue and brain tissue data available from the literature to calculate the phase shift as a function of oedema in the bulk of the brain. Experimental data were generated from bulk measurements of ex vivo homogenized pig brain tissue mixed with various volumes of physiological saline in a volume sample typical of the human brain. There is good agreement between the analytical and the experimental results. Detectable changes in phase shift begin from a frequency of about 3 MHz to 4 MHz in the tested compositions and volume. The phase shift increases with frequency and fluid content. The results suggest that measuring phase shift in the bulk of the brain has the potential for becoming a robust means for non-contact detection of oedema in the brain.

  20. Detection of Sub-Surface Water on Mars by Controlled and Natural Source Electromagnetic Induction

    NASA Technical Reports Server (NTRS)

    Connerney, J. E. P.; Acuna, M. H.

    2001-01-01

    Detection of subsurface liquid water on Mars is a leading scientific objective for Mars exploration in this decade. We describe electromagnetic induction (EM) methods that are both uniquely well suited for detection of subsurface liquid water on Mars and practical within the context of a Mars exploration program. EM induction methods are ideal for detection of more highly conducting (liquid water bearing) soils and rock beneath a more resistive overburden. A combined natural source and controlled source method offers an efficient and unambiguous characterization of the depth to liquid water and the extent of the aqueous region. The controlled source method employs an ac vertical dipole source (horizontal loop) to probe the depth to the conductor and a natural source method (gradient sounding) to characterize its conductivity-thickness product. These methods are proven in geophysical exploration and can be tailored to cope with any reasonable Mars crustal electrical conductivity. We describe a practical experiment and discuss experiment optimization to address the range of material properties likely encountered in the Mars crust.

  1. A Missile-Borne Angular Velocity Sensor Based on Triaxial Electromagnetic Induction Coils.

    PubMed

    Li, Jian; Wu, Dan; Han, Yan

    2016-09-30

    Aiming to solve the problem of the limited measuring range for angular motion parameters of high-speed rotating projectiles in the field of guidance and control, a self-adaptive measurement method for angular motion parameters based on the electromagnetic induction principle is proposed. First, a framework with type bent "I-shape" is used to design triaxial coils in a mutually orthogonal way. Under the condition of high rotational speed of a projectile, the induction signal of the projectile moving across a geomagnetic field is acquired by using coils. Second, the frequency of the pulse signal is adjusted self-adaptively. Angular velocity and angular displacement are calculated in the form of periodic pulse counting and pulse accumulation, respectively. Finally, on the basis of that principle prototype of the sensor is researched and developed, performance of measuring angular motion parameters are tested on the sensor by semi-physical and physical simulation experiments, respectively. Experimental results demonstrate that the sensor has a wide measuring range of angular velocity from 1 rps to 100 rps with a measurement error of less than 0.3%, and the angular displacement measurement error is lower than 0.2°. The proposed method satisfies measurement requirements for high-speed rotating projectiles with an extremely high dynamic range of rotational speed and high precision, and has definite value to engineering applications in the fields of attitude determination and geomagnetic navigation.

  2. A Missile-Borne Angular Velocity Sensor Based on Triaxial Electromagnetic Induction Coils

    PubMed Central

    Li, Jian; Wu, Dan; Han, Yan

    2016-01-01

    Aiming to solve the problem of the limited measuring range for angular motion parameters of high-speed rotating projectiles in the field of guidance and control, a self-adaptive measurement method for angular motion parameters based on the electromagnetic induction principle is proposed. First, a framework with type bent “I-shape” is used to design triaxial coils in a mutually orthogonal way. Under the condition of high rotational speed of a projectile, the induction signal of the projectile moving across a geomagnetic field is acquired by using coils. Second, the frequency of the pulse signal is adjusted self-adaptively. Angular velocity and angular displacement are calculated in the form of periodic pulse counting and pulse accumulation, respectively. Finally, on the basis of that principle prototype of the sensor is researched and developed, performance of measuring angular motion parameters are tested on the sensor by semi-physical and physical simulation experiments, respectively. Experimental results demonstrate that the sensor has a wide measuring range of angular velocity from 1 rps to 100 rps with a measurement error of less than 0.3%, and the angular displacement measurement error is lower than 0.2°. The proposed method satisfies measurement requirements for high-speed rotating projectiles with an extremely high dynamic range of rotational speed and high precision, and has definite value to engineering applications in the fields of attitude determination and geomagnetic navigation. PMID:27706039

  3. Computer assisted electromagnetic navigation improves accuracy in computed tomography guided interventions: A prospective randomized clinical trial

    PubMed Central

    2017-01-01

    Purpose To assess the accuracy and usability of an electromagnetic navigation system designed to assist Computed Tomography (CT) guided interventions. Materials and methods 120 patients requiring a percutaneous CT intervention (drainage, biopsy, tumor ablation, infiltration, sympathicolysis) were included in this prospective randomized trial. Nineteen radiologists participated. Conventional procedures (CT group) were compared with procedures assisted by a navigation system prototype using an electromagnetic localizer to track the position and orientation of a needle holder (NAV group). The navigation system displays the needle path in real-time on 2D reconstructed CT images extracted from the 3D CT volume. The regional ethics committee approved this study and all patients gave written informed consent. The main outcome was the distance between the planned trajectory and the achieved needle trajectory calculated from the initial needle placement. Results 120 patients were analyzable in intention-to-treat (NAV: 60; CT: 60). Accuracy improved when the navigation system was used: distance error (in millimeters: median[P25%; P75%]) with NAV = 4.1[2.7; 9.1], vs. with CT = 8.9[4.9; 15.1] (p<0.001). After the initial needle placement and first control CT, fewer subsequent CT acquisitions were necessary to reach the target using the navigation system: NAV = 2[2; 3]; CT = 3[2; 4] (p = 0.01). Conclusion The tested system was usable in a standard clinical setting and provided significant improvement in accuracy; furthermore, with the help of navigation, targets could be reached with fewer CT control acquisitions. PMID:28296957

  4. Integrated design method of MR damper and electromagnetic induction system for structural control

    NASA Astrophysics Data System (ADS)

    Lee, Heon-Jae; Moon, Seok-Jun; Jung, Hyung-Jo; Huh, Young-Cheol; Jang, Dong-Doo

    2008-03-01

    Magnetorheological (MR) dampers are one of the most advantageous control devices for civil engineering applications to natural hazard mitigation due to many good features such as small power requirement, reliability, and low price to manufacture. To reduce the responses of a structural system by using MR dampers, a control system including a power supply, control algorithm, and sensors is needed. The control system becomes complex, however, when a lot of MR dampers are applied to large-scale civil structures, such as cable-stayed bridges and high-rise buildings. Thus, it is difficult to install and/or maintain the MR damper-based control system. To overcome the above difficulties, a smart passive system was proposed, which is based on an MR damper system. The smart passive system consists of an MR damper and an electromagnetic induction (EMI) system that uses a permanent magnet and a coil. According to the Faraday law of induction, the EMI system that is attached to the MR damper can produce electric energy and the produced energy is applied to the MR damper to vary the damping characteristics of the damper. Thus, the smart passive system does not require any power at all. Besides the output of electric energy is proportional to input loads such as earthquakes, which means the smart passive system has adaptability by itself without any controller or sensors. In this paper, the integrated design method of a large-scale MR damper and Electromagnetic Induction (EMI) system is presented. Since the force of an MR damper is controllable by altering the input current generated from an EMI part, it is necessary to design an MR damper and an EMI part simultaneously. To do this, design parameters of an EMI part consisting of permanent magnet and coil as well as those of an MR damper consisting of a hydraulic-type cylinder and a magnetic circuit that controls the magnetic flux density in a fluid-flow path are considered in the integrated design procedure. As an example, a

  5. Investigating phobic specificity with standardized low resolution brain electromagnetic tomography (sLORETA).

    PubMed

    Scharmüller, Wilfried; Leutgeb, Verena; Schäfer, Axel; Schienle, Anne

    2012-10-05

    The current study investigated differential sources of late event-related potentials (ERPs) in two subtypes of specific phobia using sLORETA (standardized low resolution brain electromagnetic tomography). In two experiments, 14 spider-phobic patients (and controls), and 14 dentophobic patients (and controls) were confronted with disorder-relevant and affectively neutral pictures while an electroencephalogram was recorded. Mean ERP amplitudes were extracted in the time windows of 300-450ms (P300) and 450-800ms (late positive potential, LPP). Analyses revealed that both spider phobics and dental phobics showed enhanced current density in parietal regions (i.e., cuneus, precuneus) for the P300 time frame when exposed to disorder-specific contents. This result can be interpreted to reflect automatic attention allocation. Spider phobics additionally displayed greater current density in the insula and the anterior/posterior cingulate cortex in the LPP time window relative to controls. Most likely, the phylogentically based spider phobia is characterized by a deeper and more prolonged attention engagement than dental phobia. Our findings are in good accordance with existing brain imaging studies and underline that source localization is a useful alternative for identifying relevant cortical regions in subtypes of specific phobia.

  6. Electromagnetic wave attenuation measurements in a ring-shaped inductively coupled air plasma

    SciTech Connect

    Xiaolong, Wei; Haojun, Xu; Min, Lin; Chen, Su; Jianhai, Li

    2015-05-28

    An aerocraft with the surface, inlet and radome covered large-area inductive coupled plasma (ICP) can attenuate its radar echo effectively. The shape, thickness, and electron density (N{sub e}) distribution of ICP are critical to electromagnetic wave attenuation. In the paper, an air all-quartz ICP generator in size of 20 × 20 × 7 cm{sup 3} without magnetic confinement is designed. The discharge results show that the ICP is amorphous in E-mode and ring-shaped in H-mode. The structure of ICP stratifies into core region and edge halo in H-mode, and its width and thickness changes from power and pressure. Such phenomena are explained by the distribution of RF magnetic field, the diffusion of negative ions plasma and the variation of skin depth. In addition, the theoretical analysis shows that the N{sub e} achieves nearly uniform within the electronegative core and sharply steepens in the edge. The N{sub e} of core region is diagnosed by microwave interferometer under varied conditions (pressure in range of 10–50 Pa, power in 300–700 W). Furthermore, the electromagnetic wave attenuation measurements were carried out with the air ICP in the frequencies of 4–5 GHz. The results show that the interspaced ICP is still effective to wave attenuation, and the wave attenuation increases with the power and pressure. The measured attenuation is approximately in accordance with the calculation data of finite-different time-domain simulations.

  7. Enhanced responsiveness to parathyroid hormone and induction of functional differentiation of cultured rabbit costal chondrocytes by a pulsed electromagnetic field.

    PubMed

    Hiraki, Y; Endo, N; Takigawa, M; Asada, A; Takahashi, H; Suzuki, F

    1987-10-22

    Pulsed electromagnetic fields promote healing of delayed united and ununited fractures by triggering a series of events in fibrocartilage. We examined the effects of a pulsed electromagnetic field (recurrent bursts, 15.4 Hz, of shorter pulses of an average of 2 gauss) on rabbit costal chondrocytes in culture. A pulsed electromagnetic field slightly reduced the intracellular cyclic adenosine 3',5'-monophosphate (cAMP) level in the culture. However, it significantly enhanced cAMP accumulation in response to parathyroid hormone (PTH) to 140% of that induced by PTH in its absence, while it did not affect cAMP accumulation in response to prostaglandin E1 or prostaglandin I2. The effect on cAMP accumulation in response to PTH became evident after exposure of the cultures to the pulsed electromagnetic field for 48 h, and was dependent upon the field strength. cAMP accumulation in response to PTH is followed by induction of ornithine decarboxylase, a good marker of differentiated chondrocytes, after PTH treatment for 4 h. Consistent with the enhanced cAMP accumulation, ornithine decarboxylase activity induced by PTH was also increased by the pulsed electromagnetic field to 170% of that in cells not exposed to a pulsed electromagnetic field. Furthermore, stimulation of glycosaminoglycan synthesis, a differentiated phenotype, in response to PTH was significantly enhanced by a pulsed electromagnetic field. Thus, a pulsed electromagnetic field enhanced a series of events in rabbit costal chondrocytes in response to PTH. These findings show that exposure of chondrocytes to a pulsed electromagnetic field resulted in functional differentiation of the cells.

  8. MR damper-based semiactive control system using electromagnetic induction device

    NASA Astrophysics Data System (ADS)

    Jung, Hyung-Jo; Jang, Dong-Doo; Koo, Jeong-Hoi

    2009-03-01

    Magnetorheological (MR) damper-based semiactive control systems can be considered as one of the most advantageous control systems for natural hazard mitigation in the field of civil engineering because MR dampers have many good features such as small power requirement, reliability, and low price to manufacture. Those systems require feedback control and power supply parts to efficiently reduce the structural responses. The control system becomes complex when a lot of MR dampers are applied to large-scale civil structures, such as cable-stayed bridges and high-rise buildings, resulting in difficulties in its implementation and maintenance. To overcome the above difficulties, a new-class MR damper-based control system was recently proposed by replacing feedback control and power supply parts with an electromagnetic induction (EMI) part consisting of permanent magnets and a coil. According to the Faraday's law of electromagnetic induction, an EMI part produces electrical energy (i.e., electromotive force or induced voltage) from mechanical energy (i.e., reciprocal motions of an MR damper), which is proportional to the rate of the change of the movement of a damper. From this characteristic of an EMI part, it might be used as a response sensing device as well as an alternative power supply. In addition, some control algorithms used in the MR damper-based semiactive control systems require the measurement information on the response related to the relative velocity of the damper. In this study, the sensing capability of an EMI part is preliminarily examined for an application to the MR damper-based semiactive control system. To this end, experimental tests are carried out using the real-scale stay cable employing an MR damper with an EMI part. It is demonstrated from the tests that an EMI part could exactly extract the dynamic characteristics of the stay cable so that it might be used as a sensing device for estimating the tension force of the stay cable. In addition

  9. Combining Satellite and Ground Magnetic Measurements to Improve Estimates of Electromagnetic Induction Transfer Functions

    NASA Astrophysics Data System (ADS)

    Balasis, G.; Egbert, G. D.

    2005-12-01

    Electromagnetic (EM) induction studies using satellite and ground-based magnetic data may ultimately provide critical new constraints on the electrical conductivity of Earth's mantle. Unlike ground-based observatories, which leave large areas of the Earth (especially the ocean basins) unsampled, satellites have the potential for nearly complete global coverage. However, because the number of operating satellites is limited, spatially complex (especially non-zonal) external current sources are sampled relatively poorly by satellites at any fixed time. The comparatively much larger number of ground-based observatories provides more complete synoptic sampling of external source structure. By combining data from both satellites and observatories models of external sources can be improved, leading to more reliable global mapping of Earth conductivity. For example, estimates of EM induction transfer functions estimated from night-side CHAMP data have been previously shown to have biases which depend systematically on local time (LT). This pattern of biases suggests that a purely zonal model does not adequately describe magnetospheric sources. As a first step toward improved modeling of spatial complexity in sources, we have applied empirical orthogonal function (EOF) methods to exploratory analysis of night-side observatory data. After subtraction of the predictions of the CM4 comprehensive model, which includes a zonally symmetric storm-time correction based on Dst, we find significant non-axisymmetric, but large scale coherent variability in the mid-latitude night-side observatory residuals. Over the restricted range of local times (18:00-6:00) and latitudes (50°S to 50°N) considered, the dominant spatial mode of variability is reasonably approximated by a q21 quadrupole spherical harmonic. Temporal variability of this leading EOF mode is well correlated with Dst. Strategies for moving beyond this initial exploratory EOF analysis to combine observatory data with

  10. Planar gradiometer for magnetic induction tomography (MIT): theoretical and experimental sensitivity maps for a low-contrast phantom.

    PubMed

    Scharfetter, Hermann; Rauchenzauner, Stephan; Merwa, Robert; Biró, O; Hollaus, Karl

    2004-02-01

    Planar gradiometers (PGRAD) have particular advantages compared to solenoid receiver coils in magnetic induction tomography (MIT) for biological objects. A careful analysis of the sensitivity maps has to be carried out for perturbations within conducting objects in order to understand the performance of a PGRAD system and the corresponding implications for the inverse problem of MIT. We calculated and measured sensitivity maps for a single MIT-channel and a cylindrical tank (diameter 200 mm) with a spherical perturbation (diameter 50 mm) and with conductivities in the physiological range (0.4-0.8 S m(-1)). The excitation coil (EXC) was a solenoid (diameter 100 mm) with its axis perpendicular to the cylinder axis. As receiver a PGRAD was used. Calculations were carried out with a finite element model comparing the PGRAD and a solenoid receiver coil with its axis perpendicular to the excitation coil axis (SC90). The measured and simulated sensitivity maps agree satisfactorily within the limits of unavoidable systematic errors. In PGRAD the sensitivity is zero on the coil axis, exhibiting two local extrema near the receiver and a strong increase of the sensitivity with the distance from the coil axis. In SC90 the sensitivity map is morphologically very similar to that of the PGRAD. The maps are completely different from those known in EIT and may thus cause different implications for the inverse problem. The SC90 can, in principle, replace the mechanically and electrically more complicated PGRAD, however, the immunity to far sources of electromagnetic interference is worse, thus requiring magnetic shielding of the system.

  11. Electromagnetic induction sounding and 3D laser imaging in support of a Mars methane analogue mission

    NASA Astrophysics Data System (ADS)

    Boivin, A.; Lai, P.; Samson, C.; Cloutis, E.; Holladay, S.; Monteiro Santos, F. A.

    2013-07-01

    The Mars Methane Analogue Mission simulates a micro-rover mission whose purpose is to detect, analyze, and determine the source of methane emissions on the planet's surface. As part of this project, both an electromagnetic induction sounder (EMIS) and a high-resolution triangulation-based 3D laser scanner were tested at the Jeffrey open-pit asbestos mine to identify and characterize geological environments favourable to the occurrence of methane. The presence of serpentinite in the form of chrysotile (asbestos), magnesium carbonate, and iron oxyhydroxides make the mine a likely location for methane production. The EMIS clearly delineated the contacts between the two geological units found at the mine, peridotite and slate, which are separated by a shear zone. Both the peridotite and slate units have low and uniform apparent electrical conductivity and magnetic susceptibility, while the shear zone has much higher conductivity and susceptibility, with greater variability. The EMIS data were inverted and the resulting model captured lateral conductivity variations through the different bedrock geological units buried beneath a gravel road. The 3D point cloud data acquired by the laser scanner were fitted with triangular meshes where steeply dipping triangles were plotted in dark grey to accentuate discontinuities. The resulting images were further processed using Sobel edge detection to highlight networks of fractures which are potential pathways for methane seepage.

  12. A Novel Tactile Sensor with Electromagnetic Induction and Its Application on Stick-Slip Interaction Detection.

    PubMed

    Liu, Yanjie; Han, Haijun; Liu, Tao; Yi, Jingang; Li, Qingguo; Inoue, Yoshio

    2016-03-24

    Real-time detection of contact states, such as stick-slip interaction between a robot and an object on its end effector, is crucial for the robot to grasp and manipulate the object steadily. This paper presents a novel tactile sensor based on electromagnetic induction and its application on stick-slip interaction. An equivalent cantilever-beam model of the tactile sensor was built and capable of constructing the relationship between the sensor output and the friction applied on the sensor. With the tactile sensor, a new method to detect stick-slip interaction on the contact surface between the object and the sensor is proposed based on the characteristics of friction change. Furthermore, a prototype was developed for a typical application, stable wafer transferring on a wafer transfer robot, by considering the spatial magnetic field distribution and the sensor size according to the requirements of wafer transfer. The experimental results validate the sensing mechanism of the tactile sensor and verify its feasibility of detecting stick-slip on the contact surface between the wafer and the sensor. The sensing mechanism also provides a new approach to detect the contact state on the soft-rigid surface in other robot-environment interaction systems.

  13. Electromagnetic induction heating for single crystal graphene growth: morphology control by rapid heating and quenching.

    PubMed

    Wu, Chaoxing; Li, Fushan; Chen, Wei; Veeramalai, Chandrasekar Perumal; Ooi, Poh Choon; Guo, Tailiang

    2015-03-12

    The direct observation of single crystal graphene growth and its shape evolution is of fundamental importance to the understanding of graphene growth physicochemical mechanisms and the achievement of wafer-scale single crystalline graphene. Here we demonstrate the controlled formation of single crystal graphene with varying shapes, and directly observe the shape evolution of single crystal graphene by developing a localized-heating and rapid-quenching chemical vapor deposition (CVD) system based on electromagnetic induction heating. Importantly, rational control of circular, hexagonal, and dendritic single crystalline graphene domains can be readily obtained for the first time by changing the growth condition. Systematic studies suggest that the graphene nucleation only occurs during the initial stage, while the domain density is independent of the growth temperatures due to the surface-limiting effect. In addition, the direct observation of graphene domain shape evolution is employed for the identification of competing growth mechanisms including diffusion-limited, attachment-limited, and detachment-limited processes. Our study not only provides a novel method for morphology-controlled graphene synthesis, but also offers fundamental insights into the kinetics of single crystal graphene growth.

  14. Electromagnetic induction detector for capillary electrophoresis and its application in pharmaceutical analysis.

    PubMed

    Yang, Xiu-Juan; Chen, Zuan-Guang; Liu, Cui; Li, Ou-Lian

    2010-10-15

    A new electromagnetic induction detector for capillary electrophoresis and its application are described. The detector is consisted of an inductor, a resistor, a high-frequency signal generator and a high-frequency millivoltmeter. The conditions affecting the response of the detector, including dimension of the magnetic ring, position of the capillary, number of coil turns, frequency, excitation voltage and value of the resistor were examined and optimized. The feasibility of the proposed detector was evaluated by detection of inorganic ions and separation of amino aids. Its quantification applicability was investigated by determination of aspirin and paracetamol in pharmaceutical preparation (Akafen powder). The primary factors affecting separation efficiency, which include variety of buffer, buffer concentration, injection time and injection height and separation voltage, were researched. Experimental results demonstrated that this new detector showed a well-defined correlation between sample concentrations and responses (r=0.997-0.999), with detection limits of 30 μmol L(-1) for aspirin and 10 μmol L(-1) for paracetamol, as well as good reproducibility and stability. Compared with currently available detection techniques, this new detector has several advantages, such as simple construction, no complicated elements, ease of assembly and operation, and potential for universal applications. It can be an alternative to the traditional methods in the quality control of the pharmaceutical preparations.

  15. Radiation and Electromagnetic Induction Data Fusion for Detection of Buried Radioactive Metal Waste - 12282

    SciTech Connect

    Long, Zhiling; Wei, Wei; Turlapaty, Anish; Du, Qian; Younan, Nicolas H.; Waggoner, Charles

    2012-07-01

    At the United States Army's test sites, fired penetrators made of Depleted Uranium (DU) have been buried under ground and become hazardous waste. Previously, we developed techniques for detecting buried radioactive targets. We also developed approaches for locating buried paramagnetic metal objects by utilizing the electromagnetic induction (EMI) sensor data. In this paper, we apply data fusion techniques to combine results from both the radiation detection and the EMI detection, so that we can further distinguish among DU penetrators, DU oxide, and non- DU metal debris. We develop a two-step fusion approach for the task, and test it with survey data collected on simulation targets. In this work, we explored radiation and EMI data fusion for detecting DU, oxides, and non-DU metals. We developed a two-step fusion approach based on majority voting and a set of decision rules. With this approach, we fuse results from radiation detection based on the RX algorithm and EMI detection based on a 3-step analysis. Our fusion approach has been tested successfully with data collected on simulation targets. In the future, we will need to further verify the effectiveness of this fusion approach with field data. (authors)

  16. Calibration models for electromagnetic induction methods to assess nutrient accumulation beneath confined livestock areas.

    PubMed

    Cordeiro, Marcos R C; Ranjan, R Sri; Ferguson, Ian J

    2011-01-01

    Nutrient accumulation in soils beneath confined livestock areas is a potential source of groundwater contamination. Electromagnetic induction (EMI) has become a practical method to assess nutrient content, with multiple linear regression (MLR) as the statistical method often employed to translate EMI readings into nutrient content. The purpose of this research is to compare and contrast the performance of spatially referenced MLR models that include secondary, 'easy-to-acquire' predictor variables such as spatial coordinate locations, soil water content and elevation information with MLR models based solely on EMI readings. Six feedlot areas were surveyed with an EM38 conductivity meter and between 6 and 12 sites at each feedlot were sampled at five different depths. The electrical conductivity (EC(e)), nitrate (NO3-) and phosphate (PO4(3-)) concentrations were measured and used as response variables. Analyses were performed using two different approaches: the response variables in individual layers and response variables by combining the layers within the soil profile. The results of both MLR methods were comparable in most instances because the models preferentially incorporated predictors derived from EM38 readings. Differences between the models were more evident when predicting NO3- and PO4(3-), even though prediction of these two analytes by either method was generally poor. Combined profile analysis was more effective for defining nutrient build-up because by-layer analysis gave non-significant or poor models in many instances.

  17. Application of the theory of optimal experiments to adaptive electromagnetic-induction sensing of buried targets.

    PubMed

    Liao, Xuejun; Carin, Lawrence

    2004-08-01

    A mobile electromagnetic-induction (EMI) sensor is considered for detection and characterization of buried conducting and/or ferrous targets. The sensor may be placed on a robot and, here, we consider design of an optimal adaptive-search strategy. A frequency-dependent magnetic-dipole model is used to characterize the target at EMI frequencies. The goal of the search is accurate characterization of the dipole-model parameters, denoted bythe vector theta; the target position and orientation are a subset of theta. The sensor position and operating frequency are denoted by the parameter vector p and a measurement is represented by the pair (p, O), where O denotes the observed data. The parametersp are fixed for a given measurement, but, in the context of a sequence of measurements p may be changed adaptively. In a locally optimal sequence of measurements, we desire the optimal sensor parameters, P(N+1) for estimation of theta, based on the previous measurements (p(n), On)n=1,N. The search strategy is based on the theory of optimal experiments, as discussed in detail and demonstrated via several numerical examples.

  18. Using Electromagnetic Induction Technique to Detect Hydropedological Dynamics: Principles and Applications

    NASA Astrophysics Data System (ADS)

    Zhu, Qing; Liao, Kaihua; Doolittle, James; Lin, Henry

    2014-05-01

    Hydropedological dynamics including soil moisture variation, subsurface flow, and spatial distributions of different soil properties are important parameters in ecological, environmental, hydrological, and agricultural modeling and applications. However, technical gap exists in mapping these dynamics at intermediate spatial scale (e.g., farm and catchment scales). At intermediate scales, in-situ monitoring provides detailed data, but is restricted in number and spatial coverage; while remote sensing provides more acceptable spatial coverage, but has comparatively low spatial resolution, limited observation depths, and is greatly influenced by the surface condition and climate. As a non-invasive, fast, and convenient geophysical tool, electromagnetic induction (EMI) measures soil apparent electrical conductivity (ECa) and has great potential to bridge this technical gap. In this presentation, principles of different EMI meters are briefly introduced. Then, case studies of using repeated EMI to detect spatial distributions of subsurface convergent flow, soil moisture dynamics, soil types and their transition zones, and different soil properties are presented. The suitability, effectiveness, and accuracy of EMI are evaluated for mapping different hydropedological dynamics. Lastly, contributions of different hydropedological and terrain properties on soil ECa are quantified under different wetness conditions, seasons, and land use types using Classification and Regression Tree model. Trend removal and residual analysis are then used for further mining of EMI survey data. Based on these analyses, proper EMI survey designs and data processing are proposed.

  19. Non-standard electromagnetic induction sensor configurations: Evaluating sensitivities and applicability

    NASA Astrophysics Data System (ADS)

    Guillemoteau, Julien; Tronicke, Jens

    2015-07-01

    For near surface geophysical surveys, small-fixed offset loop-loop electromagnetic induction (EMI) sensors are usually placed parallel to the ground surface (i.e., both loops are at the same height above ground). In this study, we evaluate the potential of making measurements with a system that is not parallel to the ground; i.e., by positioning the system at different inclinations with respect to ground surface. First, we present the Maxwell theory for inclined magnetic dipoles over a homogeneous half space. By analyzing the sensitivities of such configurations, we show that varying the angle of the system would result in improved imaging capabilities. For example, we show that acquiring data with a vertical system allows detection of a conductive body with a better lateral resolution compared to data acquired using standard horizontal configurations. The synthetic responses are presented for a heterogeneous medium and compared to field data acquired in the historical Park Sanssouci in Potsdam, Germany. After presenting a detailed sensitivity analysis and synthetic examples of such ground conductivity measurements, we suggest a new strategy of acquisition that allows to better estimate the true distribution of electrical conductivity using instruments with a fixed, small offset between the loops. This strategy is evaluated using field data collected at a well-constrained test-site in Horstwalde (Germany). Here, the target buried utility pipes are best imaged using vertical system configurations demonstrating the potential of our approach for typical applications.

  20. Electromagnetic inductance plethysmography is well suited to measure tidal breathing in infants

    PubMed Central

    Eriksen, Morten; Olsen, Merete S.; Markestad, Trond; Halvorsen, Thomas

    2016-01-01

    Reliable, accurate and noninvasive methods for measuring lung function in infants are desirable. Electromagnetic inductance plethysmography has been used to perform infant spirometry and VoluSense Pediatrics (VSP) (VoluSense, Bergen, Norway) represents an updated version of this technique. We aimed to examine its accuracy compared to a validated system measuring airflow via a facemask using an ultrasonic flowmeter. We tested 30 infants with postmenstrual ages between 36 to 43 weeks and weights from 2.3 to 4.8 kg, applying both methods simultaneously and applying VSP alone. Agreement between the methods was calculated using Bland–Altman analyses and we also estimated the effect of applying the mask. Mean differences for all breathing parameters were within ±5.5% and limits of agreement between the two methods were acceptable, except perhaps for peak tidal expiratory flow (PTEF). Application of the facemask significantly increased tidal volume, minute ventilation, PTEF, the ratio of inspiratory to expiratory time and the ratio of expiratory flow at 50% of expired volume to PTEF. VSP accurately measured tidal breathing parameters and seems well suited for tidal breathing measurements in infants under treatment with equipment that precludes the use of a facemask. PMID:28053968

  1. A Novel Tactile Sensor with Electromagnetic Induction and Its Application on Stick-Slip Interaction Detection

    PubMed Central

    Liu, Yanjie; Han, Haijun; Liu, Tao; Yi, Jingang; Li, Qingguo; Inoue, Yoshio

    2016-01-01

    Real-time detection of contact states, such as stick-slip interaction between a robot and an object on its end effector, is crucial for the robot to grasp and manipulate the object steadily. This paper presents a novel tactile sensor based on electromagnetic induction and its application on stick-slip interaction. An equivalent cantilever-beam model of the tactile sensor was built and capable of constructing the relationship between the sensor output and the friction applied on the sensor. With the tactile sensor, a new method to detect stick-slip interaction on the contact surface between the object and the sensor is proposed based on the characteristics of friction change. Furthermore, a prototype was developed for a typical application, stable wafer transferring on a wafer transfer robot, by considering the spatial magnetic field distribution and the sensor size according to the requirements of wafer transfer. The experimental results validate the sensing mechanism of the tactile sensor and verify its feasibility of detecting stick-slip on the contact surface between the wafer and the sensor. The sensing mechanism also provides a new approach to detect the contact state on the soft-rigid surface in other robot-environment interaction systems. PMID:27023545

  2. Electromagnetic inductance plethysmography is well suited to measure tidal breathing in infants.

    PubMed

    Bentsen, Mariann H L; Eriksen, Morten; Olsen, Merete S; Markestad, Trond; Halvorsen, Thomas

    2016-10-01

    Reliable, accurate and noninvasive methods for measuring lung function in infants are desirable. Electromagnetic inductance plethysmography has been used to perform infant spirometry and VoluSense Pediatrics (VSP) (VoluSense, Bergen, Norway) represents an updated version of this technique. We aimed to examine its accuracy compared to a validated system measuring airflow via a facemask using an ultrasonic flowmeter. We tested 30 infants with postmenstrual ages between 36 to 43 weeks and weights from 2.3 to 4.8 kg, applying both methods simultaneously and applying VSP alone. Agreement between the methods was calculated using Bland-Altman analyses and we also estimated the effect of applying the mask. Mean differences for all breathing parameters were within ±5.5% and limits of agreement between the two methods were acceptable, except perhaps for peak tidal expiratory flow (PTEF). Application of the facemask significantly increased tidal volume, minute ventilation, PTEF, the ratio of inspiratory to expiratory time and the ratio of expiratory flow at 50% of expired volume to PTEF. VSP accurately measured tidal breathing parameters and seems well suited for tidal breathing measurements in infants under treatment with equipment that precludes the use of a facemask.

  3. Formulation for a practical implementation of electromagnetic induction coils optimized using stream functions

    NASA Astrophysics Data System (ADS)

    Reed, Mark A.; Scott, Waymond R.

    2016-05-01

    Continuous-wave (CW) electromagnetic induction (EMI) systems used for subsurface sensing typically employ separate transmit and receive coils placed in close proximity. The closeness of the coils is desirable for both packaging and object pinpointing; however, the coils must have as little mutual coupling as possible. Otherwise, the signal from the transmit coil will couple into the receive coil, making target detection difficult or impossible. Additionally, mineralized soil can be a significant problem when attempting to detect small amounts of metal because the soil effectively couples the transmit and receive coils. Optimization of wire coils to improve their performance is difficult but can be made possible through a stream-function representation and the use of partially convex forms. Examples of such methods have been presented previously, but these methods did not account for certain practical issues with coil implementation. In this paper, the power constraint introduced into the optimization routine is modified so that it does not penalize areas of high current. It does this by representing the coils as plates carrying surface currents and adjusting the sheet resistance to be inversely proportional to the current, which is a good approximation for a wire-wound coil. Example coils are then optimized for minimum mutual coupling, maximum sensitivity, and minimum soil response at a given height with both the earlier, constant sheet resistance and the new representation. The two sets of coils are compared both to each other and other common coil types to show the method's viability.

  4. An analysis of how electromagnetic induction and Faraday's law are presented in general physics textbooks, focusing on learning difficulties

    NASA Astrophysics Data System (ADS)

    Guisasola, Jenaro; Zuza, Kristina; Almudi, José-Manuel

    2013-07-01

    Textbooks are a very important tool in the teaching-learning process and influence important aspects of the process. This paper presents an analysis of the chapter on electromagnetic induction and Faraday's law in 19 textbooks on general physics for first-year university courses for scientists and engineers. This analysis was based on criteria formulated from the theoretical framework of electromagnetic induction in classical physics and students' learning difficulties concerning these concepts. The aim of the work presented here is not to compare a textbook against the ideal book, but rather to try and find a series of explanations, examples, questions, etc that provide evidence on how the topic is presented in relation to the criteria above. It concludes that despite many aspects being covered properly, there are others that deserve greater attention.

  5. A 2-axis Polydimethylsiloxane (PDMS) based electromagnetic MEMS scanning mirror for optical coherence tomography

    NASA Astrophysics Data System (ADS)

    Kim, Sehui; Lee, Changho; Kim, Jin Young; Lim, Geunbae; Kim, Jeehyun; Kim, Chulhong

    2016-03-01

    Optical coherence tomography (OCT) is a noninvasive imaging tool for visualizing cross-sectional images of biological tissues on a microscale. Various microelectromechanical system (MEMS) techniques have been applied to OCT for endoscopic catheters and handheld probes. Despite having several advantages such as compact sizes and high speeds for real-time imaging, the complexities of the fabrication processes and relatively high costs were bottlenecks for fast clinical translation and commercialization of the earlier MEMS scanners. To overcome these issues, we developed a 2-axis polydimethylsiloxane (PDMS)-based electromagnetic MEMS scanning mirror based on flexible, cost-effective, and handleable PDMS. The size of this MEMS scanner was 15 × 15 × 15 mm3. To realize the characteristics of the scanner, we obtained the DC/AC responses and scanning patterns. The measured maximum scanning angles were 16.6° and 11.6° along the X and Y axes, respectively. The resonance frequencies were 82 and 57 Hz along the X and Y axes, respectively. The scanning patterns (raster and Lissajous scan patterns) are also demonstrated by controlling the frequency and amplitude. Finally, we showed the in vivo 2D-OCT images of human fingers by using a spectral domain OCT system with a PDMSbased MEMS scanning mirror. We then reconstructed the 3D images of human fingers. The obtained field of view was 8 × 8 mm2. The PDMS-based MEMS scanning mirror has the potential to combine other optical modalities and be widely used in preclinical and clinical translation research.

  6. Low resolution brain electromagnetic tomography in a realistic geometry head model: a simulation study

    NASA Astrophysics Data System (ADS)

    Ding, Lei; Lai, Yuan; He, Bin

    2005-01-01

    It is of importance to localize neural sources from scalp recorded EEG. Low resolution brain electromagnetic tomography (LORETA) has received considerable attention for localizing brain electrical sources. However, most such efforts have used spherical head models in representing the head volume conductor. Investigation of the performance of LORETA in a realistic geometry head model, as compared with the spherical model, will provide useful information guiding interpretation of data obtained by using the spherical head model. The performance of LORETA was evaluated by means of computer simulations. The boundary element method was used to solve the forward problem. A three-shell realistic geometry (RG) head model was constructed from MRI scans of a human subject. Dipole source configurations of a single dipole located at different regions of the brain with varying depth were used to assess the performance of LORETA in different regions of the brain. A three-sphere head model was also used to approximate the RG head model, and similar simulations performed, and results compared with the RG-LORETA with reference to the locations of the simulated sources. Multi-source localizations were discussed and examples given in the RG head model. Localization errors employing the spherical LORETA, with reference to the source locations within the realistic geometry head, were about 20-30 mm, for four brain regions evaluated: frontal, parietal, temporal and occipital regions. Localization errors employing the RG head model were about 10 mm over the same four brain regions. The present simulation results suggest that the use of the RG head model reduces the localization error of LORETA, and that the RG head model based LORETA is desirable if high localization accuracy is needed.

  7. Multi-Sensor Systems Development for UXO Detection and Discrimination: Man-Portable Dual Magnetic/Electromagnetic Induction Sensor

    DTIC Science & Technology

    2008-02-01

    Portable Dual Magnetic/Electromagnetic Induction Sensor David Wright, Hollis H. Bennett, Jr., Linda Peyman Dove, John H. Ballard, Morris P...Bennett, Jr., Linda Peyman Dove, John H. Ballard, Morris P. Fields, and Tere A. Demoss Environmental Laboratory U.S. Army Engineer Research and...NUMBER 5d. PROJECT NUMBER 5e. TASK NUMBER 6. AUTHOR(S) David Wright, Hollis H. Bennett, Jr., Linda Peyman Dove, John H. Ballard

  8. Evaluation of local and integral magnitudes in metal sheets inductive levitation device by FEM electromagnetic field modeling

    SciTech Connect

    Fireteanu, V.; Craiu, O.; Curiac, R.

    1996-05-01

    This paper presents a numerical computation of a device for the horizontal casting of the inductive levitated metallic sheets. Local and integral magnitudes of electromagnetic field values are computed by means of FEM, using the FLUX-2D software and the dedicated program LEVITA. The influences of the supply frequency, magnetic saturation, and device configuration on the levitation force, induced power and transverse variation of the levitation force density are studied. Some experimental proof of the calculated magnitudes is also presented.

  9. A reconstruction algorithm of magnetoacoustic tomography with magnetic induction for an acoustically inhomogeneous tissue.

    PubMed

    Zhou, Lian; Zhu, Shanan; He, Bin

    2014-06-01

    Magnetoacoustic tomography with magnetic induction (MAT-MI) is a noninvasive electrical conductivity imaging approach that measures ultrasound wave induced by magnetic stimulation, for reconstructing the distribution of electrical impedance in a biological tissue. Existing reconstruction algorithms for MAT-MI are based on the assumption that the acoustic properties in the tissue are homogeneous. However, the tissue in most parts of human body has heterogeneous acoustic properties, which leads to potential distortion and blurring of small buried objects in the impedance images. In this study, we proposed a new algorithm for MAT-MI to image the impedance distribution in tissues with inhomogeneous acoustic speed distributions. With a computer head model constructed from MR images of a human subject, a series of numerical simulation experiments were conducted. The present results indicate that the inhomogeneous acoustic properties of tissues in terms of speed variation can be incorporated in MAT-MI imaging.

  10. Magnetic induction tomography: evaluation of the point spread function and analysis of resolution and image distortion.

    PubMed

    Merwa, Robert; Scharfetter, Hermann

    2007-07-01

    Magnetic induction tomography (MIT) is a low-resolution imaging modality used for reconstructing the changes of the passive electrical properties in a target object. For an imaging system, it is very important to give forecasts about the image quality. Both the maximum resolution and the correctness of the location of the inhomogeneities are of major interest. Furthermore, the smallest object which can be detected for a certain noise level is a criterion for the diagnostic value of an image. The properties of an MIT image are dependent on the position inside the object, the conductivity distribution and of course on the location and the number of excitation coils and receiving coils. Quantitative statements cannot be made in general but it is feasible to predict the image quality for a selected problem. For electrical impedance tomography (EIT), the theoretical limits of image quality have been studied carefully and a comprehensive analysis for MIT is necessary. Thus, a simplified analysis on resolution, dimensions and location of an inhomogeneity was carried out by means of an evaluation of the point spread function (PSF). In analogy to EIT the PSF depends strongly on the location, showing the broadest distribution in the centre of the object. Increasing the amount of regularization according to increasing measurement noise, the PSF broadens and its centre is shifted towards the borders of the object. The resolution is indirectly proportional to the width of the PSF and increases when moving from the centre towards the border of the object and decreases with increasing noise.

  11. Validation of a paleo river system derived by ground based electromagnetic induction measurements with satellite based RapidEye images

    NASA Astrophysics Data System (ADS)

    Rudolph, Sebastian; von Hebel, Christian; Ali, Mohammed; Stadler, Anja; Herbst, Michael; Montzka, Carsten; Pätzold, Stefan; Weihermüller, Lutz; van der Kruk, Jan; Vereecken, Harry

    2013-04-01

    Morphological remnants of an inactive river system that has been filled by younger sediments can provide datable proxies about past climatic conditions. However, sediment composition of their infillings is a challenge for agriculture, in particular for precision agriculture. Differential crop development and yield reduction are often a consequence of lateral and vertical textural inhomogeneities. Several studies have shown that buried river systems can be traced by the use of remote sensing. However, the appearance of crop marks strongly depends on environmental conditions, and therefore, the reliance of remotely acquired data can become time and cost expensive. Soil physical properties which are related to textural differences can be mapped fast and cost-effective by the use of near surface geophysics. Especially electromagnetic induction (EMI), which measures soil apparent conductivity (ECa), has become a tool of choice to characterize large areas in high resolution. The introduction of multiple coil EMI systems as well as the quantification of respective measurements enables a reliable multilayer inversion. The aim of this study was to map a postglacial river system on agricultural fields and to mark out buried remains such as trenches and bomb craters of World War II. In summer 2012 ten fields (17 ha) were mapped with the CMD MiniExplorer, a multiple coil EMI system especially appropriate for near surface applications, after the harvest of winter wheat and sugar beet. At elevated sandy sites meander like patterns with higher conductivity were mapped. ECa measurements were verified by textural data taken from directed soil samples and vertical ECa logs. Sediment thickness was evaluated on soil cores and electrical resistivity tomography (ERT) transects. Furthermore, ERT quantified ECa measurements were correlated with satellite as well as destructive derived leaf area index (LAI) measurements. In 3 of 71 LAI maps derived by multispectral RapidEye imagery crop

  12. The effect of receiver coil orientations on the imaging performance of magnetic induction tomography

    NASA Astrophysics Data System (ADS)

    Gürsoy, D.; Scharfetter, H.

    2009-10-01

    Magnetic induction tomography is an imaging modality which aims to reconstruct the conductivity distribution of the human body. It uses magnetic induction to excite the body and an array of sensor coils to detect the perturbations in the magnetic field. Up to now, much effort has been expended with the aim of finding an efficient coil configuration to extend the dynamic range of the measured signal. However, the merits of different sensor orientations on the imaging performance have not been studied in great detail so far. Therefore, the aim of the study is to fill the void of a systematic investigation of coil orientations on the reconstruction quality of the designs. To this end, a number of alternative receiver array designs with different coil orientations were suggested and the evaluations of the designs were performed based on the singular value decomposition. A generalized class of quality measures, the subclasses of which are linked to both the spatial resolution and uncertainty measures, was used to assess the performance on the radial and axial axes of a cylindrical phantom. The detectability of local conductivity perturbations in the phantom was explored using the reconstructed images. It is possible to draw the conclusion that the proper choice of the coil orientations significantly influences the number of usable singular vectors and accordingly the stability of image reconstruction, although the effect of increased stability on the quality of the reconstructed images was not of paramount importance due to the reduced independent information content of the associated singular vectors.

  13. Assessment of potential nutrient build-up around beef cattle production areas using electromagnetic induction.

    PubMed

    Cordeiro, Marcos R C; Ranjan, Ramanathan Sri; Cicek, Nazim

    2011-12-01

    Electromagnetic induction (EMI) has been used to map soil properties such as salinity and water content. The objective of this research is to use EMI to map the potential distribution of nutrients around beef cattle pens and to relate this distribution to major physiographic field features. Beef cattle farms in different physiographic locations were surveyed in Manitoba, Canada, using an EM-38 conductivity meter georeferenced with a GPS receiver. Samples were collected using a response surface design and analysed for electrical conductivity (ECe), which was used as a proxy for determining potential build-up of nutrients. Multiple linear regression models (MLR) were used for calibration of the EM readings. The results showed that areas 1 through 4 had ECe < or = 3.5 dSm(-1), but areas 5 and 6 exceeded this concentration and reached maximum values of 5.5 and 7.0 dS m(-1), respectively. Higher values in area 6 were probably due to the presence of a rocky layer at 0.3 m depth, leaving a thin soil layer to accumulate the nutrients. Micro-depressions played a major role in salt accumulation, with the depressions corresponding to higher values of ECe. The presence of features such as drainage ditches and compacted soils beneath roads strongly affected the direction of the plumes. Based on these results, the location of the pens on high elevations and the provision to collect the run-off from the pens were identified as good design criteria. Highly permeable soils may require a low permeability liner to capture the deep percolation and redirect it towards a collection area.

  14. Inversion of multi-frequency electromagnetic induction data for 3D characterization of hydraulic conductivity

    USGS Publications Warehouse

    Brosten, T.R.; Day-Lewis, F. D.; Schultz, G.M.; Curtis, G.P.; Lane, J.W.

    2011-01-01

    Electromagnetic induction (EMI) instruments provide rapid, noninvasive, and spatially dense data for characterization of soil and groundwater properties. Data from multi-frequency EMI tools can be inverted to provide quantitative electrical conductivity estimates as a function of depth. In this study, multi-frequency EMI data collected across an abandoned uranium mill site near Naturita, Colorado, USA, are inverted to produce vertical distribution of electrical conductivity (EC) across the site. The relation between measured apparent electrical conductivity (ECa) and hydraulic conductivity (K) is weak (correlation coefficient of 0.20), whereas the correlation between the depth dependent EC obtained from the inversions, and K is sufficiently strong to be used for hydrologic estimation (correlation coefficient of -0.62). Depth-specific EC values were correlated with co-located K measurements to develop a site-specific ln(EC)-ln(K) relation. This petrophysical relation was applied to produce a spatially detailed map of K across the study area. A synthetic example based on ECa values at the site was used to assess model resolution and correlation loss given variations in depth and/or measurement error. Results from synthetic modeling indicate that optimum correlation with K occurs at ~0.5m followed by a gradual correlation loss of 90% at 2.3m. These results are consistent with an analysis of depth of investigation (DOI) given the range of frequencies, transmitter-receiver separation, and measurement errors for the field data. DOIs were estimated at 2.0??0.5m depending on the soil conductivities. A 4-layer model, with varying thicknesses, was used to invert the ECa to maximize available information within the aquifer region for improved correlations with K. Results show improved correlation between K and the corresponding inverted EC at similar depths, underscoring the importance of inversion in using multi-frequency EMI data for hydrologic estimation. ?? 2011.

  15. Identifying and removing micro-drift in ground-based electromagnetic induction data

    NASA Astrophysics Data System (ADS)

    De Smedt, Philippe; Delefortrie, Samuël; Wyffels, Francis

    2016-08-01

    As the application of ground-based frequency domain electromagnetic induction (FDEM) surveys is on the rise, so increases the need for processing strategies that allow exploiting the full potential of these often large survey datasets. While a common issue is the detection of baseline drift affecting FDEM measurements, the impact of residual corrugations present after initial drift removal is less documented. Comparable to the influence of baseline drift, this 'micro-drift' introduces aberrant data fluctuations through time, independent of the true subsurface variability. Here, we present a method to detect micro-drift in drift-corrected FDEM survey data, therefore allowing its removal. The core of the procedure lies in approaching survey datasets as a time series. Hereby, discrete multi-level wavelet decomposition is used to isolate micro-drift in FDEM data. Detected micro-drift is then excluded in subsequent signal reconstruction to produce a more accurate FDEM dataset. While independently executed from ancillary information, tie-line measurements are used to evaluate the reliability and pitfalls of the procedure. This demonstrates how data levelling without evaluation data can increase subjectivity of the procedure, and shows the flexibility and efficiency of the approach in detecting minute drift effects. We corroborated the method through its application on three experimental field datasets, consisting of both quadrature and in-phase measurements gathered with different FDEM instruments. Through a 1D assessment of micro-drift, we show how it impacts FDEM survey data, and how it can be identified and accounted for in straightforward processing steps.

  16. Identification of buried landmines using electromagnetic induction spectroscopy: evaluation of a blind test against ground truth

    NASA Astrophysics Data System (ADS)

    Huang, Haoping; San Filipo, Bill; Norton, Steve; Won, I. J.

    2005-06-01

    The Geophex GEM-3 sensor was tested at a government test site comprised of 980 1-m squares containing buried landmines and clutter (metallic debris). Electromagnetic (EM) induction spectroscopy (EMIS) was used to discriminate between the landmines and clutter items. Receiver-operator characteristics (ROC) were constructed based on the results of the analysis. Approximately 92% of the landmines were correctly identified as such, with a false alarm rate of 12%. In this report, we present a comparison of our identification results against the ground truth. The EMIS method works well for high-metal mines for which the misfit threshold can be easily established, yielding a correct declaration in all cases without false alarms. For medium-metal mines, even though the misfit differences between the mines and clutter are not as clear as those for the high-metal mines, these mines were still identified at very low false alarm rates with the GEM-3 sensor. The low-metal mines may be discriminated from clutter if they yield reliable signals, but often at a much higher false alarm rate. The primary reason for this is that the EM signals from the low-metal mines are intrinsically weak and thus more subject to distortion by noise. There are several possibilities for improving the low-metal mine identification, including (1) increasing the upper limit of the frequency band to obtain a stronger signal and better defined spectra; (2) decreasing the size of the sensing head to further localize the region of sensitivity of the sensor; (3) displaying the spectral curves and performing the identification in real time to allow operator inspection of the spectral match; and (4) defining a generalized misfit that incorporates signal amplitude and possibly other spectral features such as the quadrature peak.

  17. Parametric vs. non-parametric statistics of low resolution electromagnetic tomography (LORETA).

    PubMed

    Thatcher, R W; North, D; Biver, C

    2005-01-01

    This study compared the relative statistical sensitivity of non-parametric and parametric statistics of 3-dimensional current sources as estimated by the EEG inverse solution Low Resolution Electromagnetic Tomography (LORETA). One would expect approximately 5% false positives (classification of a normal as abnormal) at the P < .025 level of probability (two tailed test) and approximately 1% false positives at the P < .005 level. EEG digital samples (2 second intervals sampled 128 Hz, 1 to 2 minutes eyes closed) from 43 normal adult subjects were imported into the Key Institute's LORETA program. We then used the Key Institute's cross-spectrum and the Key Institute's LORETA output files (*.lor) as the 2,394 gray matter pixel representation of 3-dimensional currents at different frequencies. The mean and standard deviation *.lor files were computed for each of the 2,394 gray matter pixels for each of the 43 subjects. Tests of Gaussianity and different transforms were computed in order to best approximate a normal distribution for each frequency and gray matter pixel. The relative sensitivity of parametric vs. non-parametric statistics were compared using a "leave-one-out" cross validation method in which individual normal subjects were withdrawn and then statistically classified as being either normal or abnormal based on the remaining subjects. Log10 transforms approximated Gaussian distribution in the range of 95% to 99% accuracy. Parametric Z score tests at P < .05 cross-validation demonstrated an average misclassification rate of approximately 4.25%, and range over the 2,394 gray matter pixels was 27.66% to 0.11%. At P < .01 parametric Z score cross-validation false positives were 0.26% and ranged from 6.65% to 0% false positives. The non-parametric Key Institute's t-max statistic at P < .05 had an average misclassification error rate of 7.64% and ranged from 43.37% to 0.04% false positives. The nonparametric t-max at P < .01 had an average misclassification rate

  18. Flow-field differences and electromagnetic-field properties of air and N2 inductively coupled plasmas

    NASA Astrophysics Data System (ADS)

    Yu, Minghao; Yamada, Kazuhiko; Takahashi, Yusuke; Liu, Kai; Zhao, Tong

    2016-12-01

    A numerical model for simulating air and nitrogen inductively coupled plasmas (ICPs) was developed considering thermochemical nonequilibrium and the third-order electron transport properties. A modified far-field electromagnetic model was introduced and tightly coupled with the flow field equations to describe the Joule heating and inductive discharge phenomena. In total, 11 species and 49 chemical reactions of air, which include 5 species and 8 chemical reactions of nitrogen, were employed to model the chemical reaction process. The internal energy transfers among translational, vibrational, rotational, and electronic energy modes of chemical species were taken into account to study thermal nonequilibrium effects. The low-Reynolds number Abe-Kondoh-Nagano k-ɛ turbulence model was employed to consider the turbulent heat transfer. In this study, the fundamental characteristics of an ICP flow, such as the weak ionization, high temperature but low velocity in the torch, and wide area of the plasma plume, were reproduced by the developed numerical model. The flow field differences between the air and nitrogen ICP flows inside the 10-kW ICP wind tunnel were made clear. The interactions between the electromagnetic and flow fields were also revealed for an inductive discharge.

  19. A theoretical model to predict both horizontal displacement and vertical displacement for electromagnetic induction-based deep displacement sensors.

    PubMed

    Shentu, Nanying; Zhang, Hongjian; Li, Qing; Zhou, Hongliang; Tong, Renyuan; Li, Xiong

    2012-01-01

    Deep displacement observation is one basic means of landslide dynamic study and early warning monitoring and a key part of engineering geological investigation. In our previous work, we proposed a novel electromagnetic induction-based deep displacement sensor (I-type) to predict deep horizontal displacement and a theoretical model called equation-based equivalent loop approach (EELA) to describe its sensing characters. However in many landslide and related geological engineering cases, both horizontal displacement and vertical displacement vary apparently and dynamically so both may require monitoring. In this study, a II-type deep displacement sensor is designed by revising our I-type sensor to simultaneously monitor the deep horizontal displacement and vertical displacement variations at different depths within a sliding mass. Meanwhile, a new theoretical modeling called the numerical integration-based equivalent loop approach (NIELA) has been proposed to quantitatively depict II-type sensors' mutual inductance properties with respect to predicted horizontal displacements and vertical displacements. After detailed examinations and comparative studies between measured mutual inductance voltage, NIELA-based mutual inductance and EELA-based mutual inductance, NIELA has verified to be an effective and quite accurate analytic model for characterization of II-type sensors. The NIELA model is widely applicable for II-type sensors' monitoring on all kinds of landslides and other related geohazards with satisfactory estimation accuracy and calculation efficiency.

  20. A Theoretical Model to Predict Both Horizontal Displacement and Vertical Displacement for Electromagnetic Induction-Based Deep Displacement Sensors

    PubMed Central

    Shentu, Nanying; Zhang, Hongjian; Li, Qing; Zhou, Hongliang; Tong, Renyuan; Li, Xiong

    2012-01-01

    Deep displacement observation is one basic means of landslide dynamic study and early warning monitoring and a key part of engineering geological investigation. In our previous work, we proposed a novel electromagnetic induction-based deep displacement sensor (I-type) to predict deep horizontal displacement and a theoretical model called equation-based equivalent loop approach (EELA) to describe its sensing characters. However in many landslide and related geological engineering cases, both horizontal displacement and vertical displacement vary apparently and dynamically so both may require monitoring. In this study, a II-type deep displacement sensor is designed by revising our I-type sensor to simultaneously monitor the deep horizontal displacement and vertical displacement variations at different depths within a sliding mass. Meanwhile, a new theoretical modeling called the numerical integration-based equivalent loop approach (NIELA) has been proposed to quantitatively depict II-type sensors’ mutual inductance properties with respect to predicted horizontal displacements and vertical displacements. After detailed examinations and comparative studies between measured mutual inductance voltage, NIELA-based mutual inductance and EELA-based mutual inductance, NIELA has verified to be an effective and quite accurate analytic model for characterization of II-type sensors. The NIELA model is widely applicable for II-type sensors’ monitoring on all kinds of landslides and other related geohazards with satisfactory estimation accuracy and calculation efficiency. PMID:22368467

  1. Integration of electromagnetic induction sensor data in soil sampling scheme optimization using simulated annealing.

    PubMed

    Barca, E; Castrignanò, A; Buttafuoco, G; De Benedetto, D; Passarella, G

    2015-07-01

    Soil survey is generally time-consuming, labor-intensive, and costly. Optimization of sampling scheme allows one to reduce the number of sampling points without decreasing or even increasing the accuracy of investigated attribute. Maps of bulk soil electrical conductivity (EC a ) recorded with electromagnetic induction (EMI) sensors could be effectively used to direct soil sampling design for assessing spatial variability of soil moisture. A protocol, using a field-scale bulk EC a survey, has been applied in an agricultural field in Apulia region (southeastern Italy). Spatial simulated annealing was used as a method to optimize spatial soil sampling scheme taking into account sampling constraints, field boundaries, and preliminary observations. Three optimization criteria were used. the first criterion (minimization of mean of the shortest distances, MMSD) optimizes the spreading of the point observations over the entire field by minimizing the expectation of the distance between an arbitrarily chosen point and its nearest observation; the second criterion (minimization of weighted mean of the shortest distances, MWMSD) is a weighted version of the MMSD, which uses the digital gradient of the grid EC a data as weighting function; and the third criterion (mean of average ordinary kriging variance, MAOKV) minimizes mean kriging estimation variance of the target variable. The last criterion utilizes the variogram model of soil water content estimated in a previous trial. The procedures, or a combination of them, were tested and compared in a real case. Simulated annealing was implemented by the software MSANOS able to define or redesign any sampling scheme by increasing or decreasing the original sampling locations. The output consists of the computed sampling scheme, the convergence time, and the cooling law, which can be an invaluable support to the process of sampling design. The proposed approach has found the optimal solution in a reasonable computation time. The

  2. Reconstruction of a medieval landscape through multi-receiver electromagnetic induction survey

    NASA Astrophysics Data System (ADS)

    De Smedt, Philippe; Van Meirvenne, Marc; Saey, Timothy; Herremans, Davy; De Reu, Jeroen; De Clercq, Wim

    2014-05-01

    In contrast to investigations on soil variability, electromagnetic induction (EMI) instruments have been used rarely for archaeogeophysical prospection. Nevertheless, the potential of EMI sensors to record simultaneously electrical and magnetic soil properties is a major asset. In non-saline environments the measured apparent electrical conductivity (ECa) mainly relates to soil texture (primarily clay), whereas the apparent magnetic susceptibility (MSa) is often heavily influenced by anthropogenic soil disturbances and iron containing material. The latest generations of multi-receiver EMI sensors allow recording the ECa and MSa of multiple soil volumes simultaneously, enabling the three-dimensional (3D) reconstruction of the natural and anthropogenic soil composition. Using a multi-receiver EMI instrument, we surveyed in detail an area of 8 ha located within a 25 km2 wetland area in the north of Belgium. The ECa data indicated a heterogeneous environment with accumulated peat, sandy outcrops and lacustrine marl. Within these sediments multiple traces of anthropogenic ditch systems were clearly visible. In addition, a number of regularly arranged punctual structures were detected with the MSa measurements. Based on these observations, two excavation trenches were positioned over the most characteristic anomalies to gain detailed insight into the archaeological features and the stratigraphy of the site. It appeared that most structures could be related to a medieval environment composed of ditches and brick fundaments of larger constructions associated with an adjacent monastery. To reconstruct the detected medieval landscape, the multi-layered EMI dataset was combined with the excavation data through an inversion procedure. While from one excavation trench stratigraphical information was used to calibrate this landscape model, geometrically correct profile information was used from the other trench to test the validity of the model. Finally, the multi-layered MSa

  3. Multi-Mode Electromagnetic Ultrasonic Lamb Wave Tomography Imaging for Variable-Depth Defects in Metal Plates

    PubMed Central

    Huang, Songling; Zhang, Yu; Wang, Shen; Zhao, Wei

    2016-01-01

    This paper proposes a new cross-hole tomography imaging (CTI) method for variable-depth defects in metal plates based on multi-mode electromagnetic ultrasonic Lamb waves (LWs). The dispersion characteristics determine that different modes of LWs are sensitive to different thicknesses of metal plates. In this work, the sensitivities to thickness variation of A0- and S0-mode LWs are theoretically studied. The principles and procedures for the cooperation of A0- and S0-mode LW CTI are proposed. Moreover, the experimental LW imaging system on an aluminum plate with a variable-depth defect is set up, based on A0- and S0-mode EMAT (electromagnetic acoustic transducer) arrays. For comparison, the traditional single-mode LW CTI method is used in the same experimental platform. The imaging results show that the computed thickness distribution by the proposed multi-mode method more accurately reflects the actual thickness variation of the defect, while neither the S0 nor the A0 single-mode method was able to distinguish thickness variation in the defect region. Moreover, the quantification of the defect’s thickness variation is more accurate with the multi-mode method. Therefore, theoretical and practical results prove that the variable-depth defect in metal plates can be successfully quantified and visualized by the proposed multi-mode electromagnetic ultrasonic LW CTI method. PMID:27144571

  4. A mathematical and numerical framework for magnetoacoustic tomography with magnetic induction

    NASA Astrophysics Data System (ADS)

    Ammari, Habib; Boulmier, Simon; Millien, Pierre

    2015-11-01

    We provide a mathematical analysis and a numerical framework for magnetoacoustic tomography with magnetic induction. The imaging problem is to reconstruct the conductivity distribution of biological tissue from measurements of the Lorentz force induced tissue vibration. We begin with reconstructing from the acoustic measurements the divergence of the Lorentz force, which is acting as the source term in the acoustic wave equation. Then we recover the electric current density from the divergence of the Lorentz force. To solve the nonlinear inverse conductivity problem, we introduce an optimal control method for reconstructing the conductivity from the electric current density. We prove its convergence and stability. We also present a point fixed approach and prove its convergence to the true solution. A new direct reconstruction scheme involving a partial differential equation is then proposed based on viscosity-type regularization to a transport equation satisfied by the electric current density field. We prove that solving such an equation yields the true conductivity distribution as the regularization parameter approaches zero. Finally, we test the three schemes numerically in the presence of measurement noise, quantify their stability and resolution, and compare their performance.

  5. A comparison of sensors for minimizing the primary signal in planar-array magnetic induction tomography.

    PubMed

    Watson, S; Igney, C H; Dössel, O; Williams, R J; Griffiths, H

    2005-04-01

    In magnetic induction tomography reducing the influence of the primary excitation field on the sensors can provide a significant improvement in SNR and/or allow the operating frequency to be reduced. For the purposes of imaging, it would be valuable if all, or a useful subset, of the detection coils could be rendered insensitive to the primary field for any excitation coil activated. Suitable schemes which have been previously suggested include the use of axial gradiometers and coil-orientation methods (Bx sensors). This paper examines the relative performance of each method through computer simulation of the sensitivity profiles produced by a single sensor, and comparison of reconstructed images produced by sensor arrays. A finite-difference model was used to determine the sensitivity profiles obtained with each type of sensor arrangement. The modelled volume was a cuboid of dimensions 50 cmx50 cmx12 cm with a uniform conductivity of 1 S m-1. The excitation coils were of 5 cm diameter and the detection coils of 5 mm diameter. The Bx sensors provided greater sensitivity than the axial gradiometers at all depths, other than on the surface layer of the volume. Images produced using a single-planar array were found to contain distortion which was reduced by the addition of a second array.

  6. 3D Magnetic Induction Maps of Nanoscale Materials Revealed by Electron Holographic Tomography

    PubMed Central

    2015-01-01

    The investigation of three-dimensional (3D) ferromagnetic nanoscale materials constitutes one of the key research areas of the current magnetism roadmap and carries great potential to impact areas such as data storage, sensing, and biomagnetism. The properties of such nanostructures are closely connected with their 3D magnetic nanostructure, making their determination highly valuable. Up to now, quantitative 3D maps providing both the internal magnetic and electric configuration of the same specimen with high spatial resolution are missing. Here, we demonstrate the quantitative 3D reconstruction of the dominant axial component of the magnetic induction and electrostatic potential within a cobalt nanowire (NW) of 100 nm in diameter with spatial resolution below 10 nm by applying electron holographic tomography. The tomogram was obtained using a dedicated TEM sample holder for acquisition, in combination with advanced alignment and tomographic reconstruction routines. The powerful approach presented here is widely applicable to a broad range of 3D magnetic nanostructures and may trigger the progress of novel spintronic nonplanar nanodevices. PMID:27182110

  7. The application of a priori structural information based regularization in image reconstruction in magnetic induction tomography

    NASA Astrophysics Data System (ADS)

    Dekdouk, B.; Ktistis, C.; Yin, W.; Armitage, D. W.; Peyton, A. J.

    2010-04-01

    Magnetic induction tomography (MIT) is a non-invasive contactless modality that could be capable of imaging the conductivity distribution of biological tissues. In this paper we consider the possibility of using absolute MIT voltage measurements for monitoring the progress of a peripheral hemorrhagic stroke in a human brain. The pathology is modelled as a local blood accumulation in the white matter. The solution of the MIT inverse problem is nonlinear and ill-posed and hence requires the use of a regularisation method. In this paper, we describe the construction and present the performance of a regularisation matrix based on a priori structural information of the head tissues obtained from a very recent MRI scan. The method takes the MRI scan as an initial state of the stroke and constructs a learning set containing the possible conductivity distributions of the current state of the stroke. This data is used to calculate an approximation of the covariance matrix and then a subspace is constructed using principal component analysis (PCA). It is shown by simulations the method is capable of producing a representative reconstruction of a stroke compared to smoothing Tikhonov regularization in a simplified model of the head.

  8. Sensitivity maps and system requirements for magnetic induction tomography using a planar gradiometer.

    PubMed

    Rosell, J; Casañas, R; Scharfetter, H

    2001-02-01

    We evaluated analytically and experimentally the performance of a planar gradiometer as a sensing element in a system for magnetic induction tomography. A system using an excitation coil and a planar gradiometer was compared against a system with two coils. We constructed one excitation coil, two different sensing elements and a high-resolution phase detector. The first sensor was a PCB square spiral coil with seven turns. The second sensor was a PCB planar gradiometer with two opposite square spirals of seven turns, with a distance between centres of 8 cm. Theoretical sensitivity maps were derived from basic equations and compared with experimental data obtained at 150 kHz. The experimental sensitivity maps were obtained measuring the perturbation produced by a brass sphere of 12 mm in empty space. The advantage of using a gradiometer is that it can be adjusted to give a minimum signal for homogeneous objects, while increasing the sensitivity to local perturbations of the conductivity. Results show that a system using a planar gradiometer as detector has less demanding requirements for the electronic system than a system using simple coils.

  9. A multi-channel magnetic induction tomography measurement system for human brain model imaging.

    PubMed

    Xu, Zheng; Luo, Haijun; He, Wei; He, Chuanhong; Song, Xiaodong; Zahng, Zhanglong

    2009-06-01

    This paper proposes a multi-channel magnetic induction tomography measurement system for biological conductivity imaging in a human brain model. A hemispherical glass bowl filled with a salt solution is used as the human brain model; meanwhile, agar blocks of different conductivity are placed in the solution to simulate the intracerebral hemorrhage. The excitation and detection coils are fixed co-axially, and the axial gradiometer is used as the detection coil in order to cancel the primary field. On the outer surface of the glass bowl, 15 sensor units are arrayed in two circles as measurement parts, and a single sensor unit for cancelling the phase drift is placed beside the glass bowl. The phase sensitivity of our system is 0.204 degrees /S m(-1) with the excitation frequency of 120 kHz and the phase noise is in the range of -0.03 degrees to +0.05 degrees . Only the coaxial detection coil is available for each excitation coil; therefore, 15 phase data are collected in each measurement turn. Finally, the two-dimensional images of conductivity distribution are obtained using an interpolation algorithm. The frequency-varying experiment indicates that the imaging quality becomes better as the excitation frequency is increased.

  10. Electromagnetic-Optical Coherence Tomography Guidance of Transbronchial Solitary Pulmonary Nodule Biopsy

    DTIC Science & Technology

    2015-07-01

    and electromagnetic (EM) navigation for spatial guidance to targeted lung nodules, and OCT for microscopic volumetric imaging. The OCT optic fiber...imaging of, and navigation to, SPN for transbronchial biopsy, and (Aim 2) conduct a preclinical study to demonstrate the feasibility of EM-OCT biopsy...guidance of artificial SPN (aSPN) in living swine. 2. KEYWORDS Electromagnetic Navigation , Biopsy Guidance, Optical Microscopy, Optical Coherence

  11. Comparing bulk electrical conductivities spatial series obtained by Time Domain Reflectometry and Electromagnetic Induction sensors

    NASA Astrophysics Data System (ADS)

    Saeed, Ali; Ajeel, Ali; dragonetti, giovanna; Comegna, Alessandro; Lamaddalena, Nicola; Coppola, Antonio

    2016-04-01

    The ability to determine and monitor the effects of salts on soils and plants, are of great importance to agriculture. To control its harmful effects, soil salinity needs to be monitored in space and time. This requires knowledge of its magnitude, temporal dynamics, and spatial variability. Conventional ground survey procedures by direct soil sampling are time consuming, costly and destructive. Alternatively, soil salinity can be evaluated by measuring the bulk electrical conductivity (σb) directly in the field. Time domain reflectometry (TDR) sensors allow simultaneous measurements of water content, θ, and σb. They may be calibrated for estimating the electrical conductivity of the soil solution (σw). However, they have a relatively small observation window and thus they are thought to only provide local-scale measurements. The spatial range of the sensors is limited to tens of centimeters and extension of the information to a large area can be problematic. Also, information on the vertical distribution of the σb soil profile may only be obtained by installing sensors at different depths. In this sense, the TDR may be considered as an invasive technique. Compared to the TDR, other geophysical methods based for example on Electromagnetic Induction (EMI) techniques are non-invasive methods and represent a viable alternative to traditional techniques for soil characterization. The problem is that all these techniques give depth-weighted apparent electrical conductivity (σa) measurements, depending on the specific depth distribution of the σb, as well as on the depth response function of the sensor used. In order to deduce the actual distribution of the bulk electrical conductivity, σb, in the soil profile, one needs to invert the signal coming from EMI. Because of their relatively lower observation window, TDR sensors provide quasi-point values and do not adequately integrate the spatial variability of the chemical concentration distribution in the soil

  12. Induction of tamoxifen resistance in breast cancer cells by ELF electromagnetic fields

    SciTech Connect

    Girgert, Rainer . E-mail: rainer.girgert@med.uni-goettingen.de; Schimming, Hartmut; Koerner, Wolfgang; Gruendker, Carsten; Hanf, Volker

    2005-11-04

    The incidence of breast cancer in western societies has been rising ever since the Second World War. Besides the exposure to a multitude of new chemical compounds, electromagnetic field exposure has been linked to breast cancer through a radiation-mediated anti-melatonin pathway. We investigated, whether low-frequency electromagnetic field exposure interferes with the anti-estrogenic activity of tamoxifen. Two different clones of the breast cancer cell line MCF-7 were exposed to highly homogeneous 50 Hz electromagnetic fields and IC{sub 50} values were calculated from dose-response curves of tamoxifen at various field intensities. An intensity-dependent shift of tamoxifen dose-response curves to higher concentrations with a maximal response at 1.2 {mu}T was observed. Hypothetically, electromagnetic field exposure could contribute to tamoxifen resistance observed in breast cancer after long-term treatment.

  13. Induction of tamoxifen resistance in breast cancer cells by ELF electromagnetic fields.

    PubMed

    Girgert, Rainer; Schimming, Hartmut; Körner, Wolfgang; Gründker, Carsten; Hanf, Volker

    2005-11-04

    The incidence of breast cancer in western societies has been rising ever since the Second World War. Besides the exposure to a multitude of new chemical compounds, electromagnetic field exposure has been linked to breast cancer through a radiation-mediated anti-melatonin pathway. We investigated, whether low-frequency electromagnetic field exposure interferes with the anti-estrogenic activity of tamoxifen. Two different clones of the breast cancer cell line MCF-7 were exposed to highly homogeneous 50Hz electromagnetic fields and IC(50) values were calculated from dose-response curves of tamoxifen at various field intensities. An intensity-dependent shift of tamoxifen dose-response curves to higher concentrations with a maximal response at 1.2muT was observed. Hypothetically, electromagnetic field exposure could contribute to tamoxifen resistance observed in breast cancer after long-term treatment.

  14. Reconstruction of the shape of conductivity spectra using differential multi-frequency magnetic induction tomography.

    PubMed

    Brunner, Patricia; Merwa, Robert; Missner, Andreas; Rosell, Javier; Hollaus, Karl; Scharfetter, Hermann

    2006-05-01

    Magnetic induction tomography (MIT) of biological tissue is used for the reconstruction of the complex conductivity distribution kappa inside the object under investigation. It is based on the perturbation of an alternating magnetic field caused by the object and can be used in all applications of electrical impedance tomography (EIT) such as functional lung monitoring and assessment of tissue fluids. In contrast to EIT, MIT does not require electrodes and magnetic fields can also penetrate non-conducting barriers such as the skull. As in EIT, the reconstruction of absolute conductivity values is very difficult because of the method's sensitivity to numerical errors and noise. To overcome this problem, image reconstruction in EIT is often done differentially. Analogously, this concept has been adopted for MIT. Two different methods for differential imaging are applicable. The first one is state-differential, for example when the conductivity change between inspiration and expiration in the lung regions is being detected. The second one is frequency-differential, which is of high interest in motionless organs like the brain, where a state-differential method cannot be applied. An equation for frequency-differential MIT was derived taking into consideration the frequency dependence of the sensitivity matrix. This formula is valid if we can assume that only small conductivity changes occur. In this way, the non-linear inverse problem of MIT can be approximated by a linear one (depending only on the frequency), similar to in EIT. Keeping this limitation in mind, the conductivity changes between one or more reference frequencies and several measurement frequencies were reconstructed, yielding normalized conductivity spectra. Due to the differential character of the method, these spectra do not provide absolute conductivities but preserve the shape of the spectrum. The validity of the method was tested with artificial data generated with a spherical perturbation within a

  15. Experimental verification of sensing capability of an electromagnetic induction system for an MR fluid damper-based control system

    NASA Astrophysics Data System (ADS)

    Jung, H. J.; Jang, D. D.; Cho, S. W.; Koo, J. H.

    2009-02-01

    This paper investigates the sensing capability of an Electromagnetic Induction (EMI) system that is incorporated in a vibration control system based on MR fluid dampers. The EMI system, consisting of permanent magnets and coils, converts reciprocal motions (kinetic energy) of MR damper into electrical energy (electromotive force or emf). According to the Faraday's law of electromagnetic induction, the emf signal, produced from the EMI, is proportional to the velocity of the motion. Thus, the induced voltage (emf) signal is able to provide the necessary measurement information (i.e., relative velocity across the damper). In other words, the EMI can act as a sensor in the MR damper system. In order to evaluate the proposed concept of the EMI sensor, an EMI system was constructed and integrated into an MR damper system. The emf signal is experimentally compared with the velocity signal by conducting a series of shaking table tests. The results show that the induced emf voltage signal well agreed with the relative velocity.

  16. Geophysical investigation of Red Devil mine using direct-current resistivity and electromagnetic induction, Red Devil, Alaska, August 2010

    USGS Publications Warehouse

    Burton, Bethany L.; Ball, Lyndsay B.

    2011-01-01

    Red Devil Mine, located in southwestern Alaska near the Village of Red Devil, was the state's largest producer of mercury and operated from 1933 to 1971. Throughout the lifespan of the mine, various generations of mills and retort buildings existed on both sides of Red Devil Creek, and the tailings and waste rock were deposited across the site. The mine was located on public Bureau of Land Management property, and the Bureau has begun site remediation by addressing mercury, arsenic, and antimony contamination caused by the minerals associated with the ore deposit (cinnabar, stibnite, realgar, and orpiment). In August 2010, the U.S. Geological Survey completed a geophysical survey at the site using direct-current resistivity and electromagnetic induction surface methods. Eight two-dimensional profiles and one three-dimensional grid of direct-current resistivity data as well as about 5.7 kilometers of electromagnetic induction profile data were acquired across the site. On the basis of the geophysical data and few available soil borings, there is not sufficient electrical or electromagnetic contrast to confidently distinguish between tailings, waste rock, and weathered bedrock. A water table is interpreted along the two-dimensional direct-current resistivity profiles based on correlation with monitoring well water levels and a relatively consistent decrease in resistivity typically at 2-6 meters depth. Three settling ponds used in the last few years of mine operation to capture silt and sand from a flotation ore processing technique possessed conductive values above the interpreted water level but more resistive values below the water level. The cause of the increased resistivity below the water table is unknown, but the increased resistivity may indicate that a secondary mechanism is affecting the resistivity structure under these ponds if the depth of the ponds is expected to extend below the water level. The electromagnetic induction data clearly identified the

  17. Combining ground penetrating radar and electromagnetic induction for industrial site characterization

    NASA Astrophysics Data System (ADS)

    Van De Vijver, Ellen; Van Meirvenne, Marc; Saey, Timothy; De Smedt, Philippe; Delefortrie, Samuël; Seuntjens, Piet

    2014-05-01

    Industrial sites pose specific challenges to the conventional way of characterizing soil and groundwater properties through borehole drilling and well monitoring. The subsurface of old industrial sites typically exhibits a large heterogeneity resulting from various anthropogenic interventions, such as the dumping of construction and demolition debris and industrial waste. Also larger buried structures such as foundations, utility infrastructure and underground storage tanks are frequently present. Spills and leaks from industrial activities and leaching of buried waste may have caused additional soil and groundwater contamination. Trying to characterize such a spatially heterogeneous medium with a limited number of localized observations is often problematic. The deployment of mobile proximal soil sensors may be a useful tool to fill up the gaps in between the conventional observations, as these enable measuring soil properties in a non-destructive way. However, because the output of most soil sensors is affected by more than one soil property, the application of only one sensor is generally insufficient to discriminate between all contributing factors. To test a multi-sensor approach, we selected a study area which was part of a former manufactured gas plant site located in one of the seaport areas of Belgium. It has a surface area of 3400 m² and was the location of a phosphate production unit that was demolished at the end of the 1980s. Considering the long and complex history of the site we expected to find a typical "industrial" soil. Furthermore, the studied area was located between buildings of the present industry, entailing additional practical challenges such as the presence of active utilities and aboveground obstacles. The area was surveyed using two proximal soil sensors based on two different geophysical methods: ground penetrating radar (GPR), to image contrasts in dielectric permittivity, and electromagnetic induction (EMI), to measure the apparent

  18. B-scan based acoustic source reconstruction for magnetoacoustic tomography with magnetic induction (MAT-MI).

    PubMed

    Mariappan, Leo; Li, Xu; He, Bin

    2011-03-01

    We present in this study, an acoustic source reconstruction method using focused transducer with B-mode imaging for magnetoacoustic tomography with magnetic induction (MAT-MI). MAT-MI is an imaging modality proposed for noninvasive conductivity imaging with high spatial resolution. In MAT-MI, acoustic sources are generated in a conductive object by placing it in a static and a time-varying magnetic field. The acoustic waves from these sources propagate in all directions and are collected with transducers placed around the object. The collected signal is then used to reconstruct the acoustic source distribution and to further estimate the electrical conductivity distribution of the object. A flat piston transducer acting as a point receiver has been used in earlier MAT-MI systems to collect acoustic signals. In this study, we propose to use B-mode scan scheme with a focused transducer that gives a signal gain in its focus region and improves the MAT-MI signal quality. A simulation protocol that can take into account different transducer designs and scan schemes for MAT-MI imaging is developed and used in our evaluation of different MAT-MI system designs. It is shown in our computer simulations that as compared to the earlier approach, the MAT-MI system using B-scan with a focused transducer allows MAT-MI imaging at a closer distance and has improved system sensitivity. In addition, the B-scan imaging technique allows reconstruction of the MAT-MI acoustic sources with a discrete number of scanning locations, which greatly increases the applicability of the MAT-MI approach, especially when a continuous acoustic window is not available in real clinical applications. We have also conducted phantom experiments to evaluate the proposed method, and the reconstructed image shows a good agreement with the target phantom.

  19. Joint inversion of multi-configuration electromagnetic induction measurements to estimate soil wetting patterns during surface drip irrigation

    NASA Astrophysics Data System (ADS)

    Jadoon, Khan Z.; Moghadas, Davood; Jadoon, Aurangzeb; Missimer, Thomas M.; McCabe, Matthew

    2014-05-01

    In arid and semi-arid regions, development of precise information on the soil wetting pattern is important to optimize drip irrigation system design for sustainable agricultural water management. Usually mathematical models are commonly used to describe infiltration from a point source to design and manage drip irrigation systems. The extent to which water migrates laterally and vertically away from the drip emitter depends on many factors, including dripper discharge rate, the frequency of water application, duration of drip emission, the soil hydraulic characteristics, initial conditions, evaporation, root water uptake and root distribution patterns. However, several simplified assumptions in the mathematical models affect their utility to provide useful design information. In this respect, non-invasive geophysical methods, i.e., low frequency electromagnetic induction (EMI) systems are becoming powerful tools to map spatial and temporal soil moisture patterns due to fast measurement capability and sensitivity to soil water content and salinity. In this research, a new electromagnetic system, the CMD mini-Explorer, is used for soil characterization to measure the wetting patterns of drip irrigation systems using joint inversion of multi-configuration EMI measurements. Six transects of EMI measurements were carried out in a farm where Acacia trees are irrigated with brackish water using a drip irrigation system. EMI reference data (ground-truths) were calculated using vertical soil electrical conductivity recorded in different trenches along one of the measurement transects. Reference data is used for calibration to minimize the instrumental shifts which often occur in EMI data. Global and local optimization algorithms are used sequentially, to minimize the misfit between the measured and modeled apparent electrical conductivity (δa) to reconstruct the vertical electrical conductivity profile. The electromagnetic forward model based on full solution of Maxwell

  20. Collection, processing, and quality assurance of time-series electromagnetic-induction log datasets, 1995–2016, south Florida

    USGS Publications Warehouse

    Prinos, Scott T.; Valderrama, Robert

    2016-12-13

    Time-series electromagnetic-induction log (TSEMIL) datasets are collected from polyvinyl-chloride cased or uncased monitoring wells to evaluate changes in water conductivity over time. TSEMIL datasets consist of a series of individual electromagnetic-induction logs, generally collected at a frequency of once per month or once per year that have been compiled into a dataset by eliminating small uniform offsets in bulk conductivity between logs probably caused by minor variations in calibration. These offsets are removed by selecting a depth at which no changes are apparent from year to year, and by adjusting individual logs to the median of all logs at the selected depth. Generally, the selected depths are within the freshwater saturated part of the aquifer, well below the water table. TSEMIL datasets can be used to monitor changes in water conductivity throughout the full thickness of an aquifer, without the need for long open-interval wells which have, in some instances, allowed vertical water flow within the well bore that has biased water conductivity profiles. The TSEMIL dataset compilation process enhances the ability to identify small differences between logs that were otherwise obscured by the offsets. As a result of TSEMIL dataset compilation, the root mean squared error of the linear regression between bulk conductivity of the electromagnetic-induction log measurements and the chloride concentration of water samples decreased from 17.4 to 1.7 millisiemens per meter in well G–3611 and from 3.7 to 2.2 millisiemens per meter in well G–3609. The primary use of the TSEMIL datasets in south Florida is to detect temporal changes in bulk conductivity associated with saltwater intrusion in the aquifer; however, other commonly observed changes include (1) variations in bulk conductivity near the water table where water saturation of pore spaces might vary and water temperature might be more variable, and (2) dissipation of conductive water in high-porosity rock

  1. Magnetoacoustic tomography with magnetic induction (MAT-MI) for imaging electrical conductivity of biological tissue: a tutorial review

    NASA Astrophysics Data System (ADS)

    Li, Xu; Yu, Kai; He, Bin

    2016-09-01

    Magnetoacoustic tomography with magnetic induction (MAT-MI) is a noninvasive imaging method developed to map electrical conductivity of biological tissue with millimeter level spatial resolution. In MAT-MI, a time-varying magnetic stimulation is applied to induce eddy current inside the conductive tissue sample. In the presence of a static magnetic field, the Lorentz force acting on the induced eddy current drives mechanical vibrations producing detectable ultrasound signals. These ultrasound signals can then be acquired to reconstruct a map related to the sample’s electrical conductivity contrast. This work reviews fundamental ideas of MAT-MI and major techniques developed in recent years. First, the physical mechanisms underlying MAT-MI imaging are described, including the magnetic induction and Lorentz force induced acoustic wave propagation. Second, experimental setups and various imaging strategies for MAT-MI are reviewed and compared, together with the corresponding experimental results. In addition, as a recently developed reverse mode of MAT-MI, magneto-acousto-electrical tomography with magnetic induction is briefly reviewed in terms of its theory and experimental studies. Finally, we give our opinions on existing challenges and future directions for MAT-MI research. With all the reported and future technical advancement, MAT-MI has the potential to become an important noninvasive modality for electrical conductivity imaging of biological tissue.

  2. Study on Metal Detection with an Electromagnetic Induction Probe Utilizing a Rotating Magnetic Field

    NASA Astrophysics Data System (ADS)

    Koyama, Kiyoshi; Hoshikawa, Hiroshi; Sakon, Toshikazu

    The present paper describes an investigation conducted on metal detection with a scanning probe. The authors applied a rotating magnetic field probe to metal detection. The rotating magnetic field probe is composed of two vertically placed rectangular exciting coils and a circular detecting coil. The experimental results confirmed that the probe can detect metal objects and provide more information about their shape, direction, and electromagnetic characteristics than conventional metal detector probes. A two-dimensional signal display shows a blurred image of the metal object and the signal phase indicates the object's direction and electromagnetic characteristics. The experimental results showed that excellent restoration of the surface shapes of metal objects can be obtained for both magnetic and nonmagnetic metals under present conditions. There is also a possibility that the rough shape of a metal object can be estimated from the restored image.

  3. A new type of gradiometer for the receiving circuit of magnetic induction tomography (MIT).

    PubMed

    Scharfetter, Hermann; Merwa, Robert; Pilz, Karl

    2005-04-01

    Magnetic induction tomography (MIT) is a low-resolution imaging modality which aims at the three-dimensional (3D) reconstruction of the electrical conductivity in objects from alternating magnetic fields. In MIT systems the magnetic field perturbations to be detected are very small when compared to the excitation field (ppm range). The voltage which is induced by the excitation field in the receiver coils must be suppressed for providing sufficient dynamic range. In the past, two very efficient strategies were proposed: adjusted planar gradiometers (PGRAD) and the orientation of a receiver coil with respect to the excitation coil such that the net magnetic flow is zero (zero flow coil, ZFC). In contrast to the PGRAD no voltage is induced in the ZFC by the main field. This is advantageous because two comparatively high voltages in the two gradiometer coils can never be subtracted perfectly, thus leaving a residual voltage which is prone to drift. However, a disadvantage of the ZFC is the higher susceptibility to interferences from far RF sources. In contrast, in the gradiometer such interferences are cancelled to a high degree. We developed a new type of gradiometer (zero flow gradiometer, ZFGRAD) which combines the advantages of ZFC and PGRAD. All three systems were compared with respect to sensitivity and perturbation to signal ratio (PSR) defined as the ratio of the signal change due to a magnetic perturbation field at the carrier frequency and the signal change due to shifting a metallic sphere between two test points. The spatial sensitivity of the three systems was found to be very similar. The PSR of the ZFGRAD was more than 12 times lower than that of the ZFC. Finally, the feasibility of image reconstruction with two arrays of eight excitation coils and eight ZFGRAD, respectively, was shown with a single-step Gauss-Newton reconstructor and simulated measurement data generated for a cylindrical tank with a spherical perturbation. The resulting images show a

  4. Automated, non-metallic measurement facility for testing and development of electromagnetic induction sensors for landmine detection

    NASA Astrophysics Data System (ADS)

    Larson, Gregg D.; Scott, Waymond R., Jr.

    2009-05-01

    For development of electromagnetic induction (EMI) sensors for landmine detection, a testing facility has been established for automated measurements of typical targets with both individual sensors and arrays of sensors. A six-degree of freedom positioner has been built with five automated axes (three translational stages and two rotational stages) and one manual axis for target characterizations with no metal within the measurement volume. Translational stages utilize commercially-available linear positioner hardware. Rotational stages have been customized using nonmetallic components to position the targets within the measurement volume. EMI sensors are held fixed in one location while the positioner orients the targets and moves them along a prescribed path through the region surrounding the sensor. The automated movement is computer-controlled and data are acquired continuously. Data are presented from three-dimensional scans of targets at various orientations. Typical targets include shell casings, wire loops, ball bearings, and landmines.

  5. Ultra-high sensitive and high resolution optical coherence tomography using a laser induced electromagnetic dipole

    NASA Astrophysics Data System (ADS)

    Kuroda, Hiroto; Baba, Motoyoshi; Suzuki, Masayuki; Yoneya, Shin

    2013-09-01

    Utilizing an optical coherence tomography measurement, we have developed a technique that actively uses a dielectric response due to an induced dipole moment caused by a mode-locked pulsed laser light source. Irradiated laser light in the material induces a photo-induced electric dipole resulting in a refractive index change for its strong electric field. Using this technique, we obtained a highly sensitive fundus retina tomogram of a human eye in vivo with a resolution of 1.3 μm by single scanning for 20 ms using 8 fs mode-locked pulse laser light with a 350 nm spread spectrum.

  6. The effect of pulsed electromagnetic fields and dehydroepiandrosterone on viability and osteo-induction of human mesenchymal stem cells.

    PubMed

    Kaivosoja, Emilia; Sariola, Veikko; Chen, Yan; Konttinen, Yrjö T

    2015-01-01

    The hypothesis of this work was that human bone marrow-derived mesenchymal stem cells (MSCs) are regulated by pulsed electromagnetic fields (PEMFs) and by intracrine conversion of an adrenal prohormone to dihydrotestosterone. The effect of PEMF and dehydroepiandrosterone (DHEA) on viability and osteogenic differentiation of human MSCs and on the viability of osteoblastic SaOS-2 cells was evaluated. It was found that PEMF promoted the viability rate of both cell types, whereas DHEA decreased the viability rate in a concentration-dependent manner. PEMF did not have major effects on osteo-induction at this low seeding density level (3000 cells/cm(2) ). Instead, DHEA, after MSC-mediated and 5α-reductase-dependent conversion to dihydrotestosterone, clearly promoted the osteo-induction of MSCs induced with β-glyserophosphate, ascorbate and dexamethasone. Alkaline phosphatase (ALP), SMAD1, RUNX2, osteopontin (OP) and osteocalcin (OC) RNA levels were increased and alizarin red S- and hydroxyapatite-specific OsteoImage(TM) stainings disclosed a promoted mineralization process. In addition, DHEA increased OP and OC mRNA levels of non-induced MSCs. A sequential use of mitogenic PEMF early during the fracture healing, followed by later administration of DHEA with osteogenic differentiating effect, might be worth subjecting to a randomized clinical trial.

  7. Effect of 900 MHz Electromagnetic Radiation on the Induction of ROS in Human Peripheral Blood Mononuclear Cells

    PubMed Central

    Kazemi, E.; Mortazavi, S. M. J.; Ali-Ghanbari, A.; Sharifzadeh, S.; Ranjbaran, R.; Mostafavi-pour, Z.; Zal, F.; Haghani, M.

    2015-01-01

    Background Despite numerous studies over a decade, it still remains controversial about the biological effects of RF EMF emitted by mobile phone telephony. Objective Here we investigated the effect of 900 MHz GSM on the induction of oxidative stress and the level of intracellular reactive oxygen species (ROS) in human mononuclear cells, monocytes and lymphocytes as defence system cells. Method 6 ml Peripheral Blood samples were obtained from 13 healthy volunteers (21-30 year-old). Each sample was devided into 2 groups: one was exposed RF radiation emitted from a mobile phone simulator for 2 hour and the other used as control group which was not exposed to any fields. After that, mononuclear cells were isolated from peripheral blood by density gradient centrifugation in Ficoll-Paque. The intracellular ROS content in monocytes and lymphocytes was measured by the CM-H2DCFDA fluorescence probe using flowcytometry technique. Results Our results showed significant increase in  ROS production after exposure in population rich in monocytes. This effect was not significant in population rich in lymphocytes in comparison with non exposed cells. Conclusion The results obtained in this study clearly showed the oxidative stress induction capability of RF electromagnetic field in the portion of PBMCs mostly in monocytes, like the case of exposure to micro organisms, although the advantages or disadvantages of this effect should be evaluated. PMID:26396966

  8. Induction of Oxidation in Living Cells by Time-Varying Electromagnetic Fields

    NASA Technical Reports Server (NTRS)

    Stolc, Viktor

    2015-01-01

    We are studying how biological systems can harness quantum effects of time varying electromagnetic (EM) waves as the time-setting basis for universal biochemical organization via the redox cycle. The effects of extremely weak EM field on the biochemical redox cycle can be monitored through real-time detection of oxidation-induced light emissions of reporter molecules in living cells. It has been shown that EM fields can also induce changes in fluid transport rates through capillaries (approximately 300 microns inner diameter) by generating annular proton gradients. This effect may be relevant to understanding cardiovascular dis-function in spaceflight, beyond the ionosphere. Importantly, we show that these EM effects can be attenuated using an active EM field cancellation device. Central for NASA's Human Research Program is the fact that the absence of ambient EM field in spaceflight can also have a detrimental influence, namely via increased oxidative damage, on DNA replication, which controls heredity.

  9. Sounding of Europa's interior using multi-frequency electromagnetic induction from a Europa orbiter

    NASA Astrophysics Data System (ADS)

    Khurana, K. K.; Kivelson, M. G.; Russell, C. T.

    2000-12-01

    Magnetic field observations from Galileo have shown that Europa induces a strong response to the varying field of Jupiter's magnetosphere. These observations are consistent with a global conductor located close to the surface. Khurana et al. [1998] and Kivelson et al. [1999] have shown that a moon-wide ocean with a conductivity similar to the Earth's ocean and having a thickness of at least 6 km could produce the observed induction signature. Many other geological and geophysical observations are consistent with this interpretation (See Pappalardo et al. [1999] for further details.). The magnetic induction signature at a single frequency can also be explained with a model in which the conducting layer is thinner (thicker) but has higher (lower) conductivity. The initial work relied on the variations of the time varying field at the synodic rotation period of Jupiter (as seen in the rest frame of the moon) to infer the interior structure of Europa. We have extended the initial analysis by showing that the spectrum of the primary field contains several other important frequencies. We single out one frequency-corresponding to the orbital period of Europa-for further examination. We show that by modeling the induction response at this frequency in addition to the previously used synodic frequency for a range of ocean shell thicknesses and conductivities, the ocean conductivity and the thickness of the ocean at Europa can be determined uniquely. We discuss how the measurements from an orbiting spacecraft can be decomposed into the internal (which is the secondary field) and external (the primary imposed field) components not only for the steady field but also for the varying field.

  10. Towards a method to differentiate chronic disorder of consciousness patients' awareness: The Low-Resolution Brain Electromagnetic Tomography Analysis.

    PubMed

    Naro, Antonino; Bramanti, Placido; Leo, Antonino; Cacciola, Alberto; Bramanti, Alessia; Manuli, Alfredo; Calabrò, Rocco Salvatore

    2016-09-15

    Assessing residual signs of awareness in patients suffering from chronic disorders of consciousness (DOC) is a challenging issue. DOC patient behavioral assessment is often doubtful since some individuals may retain covert traces of awareness; thus, some Unresponsive Wakefulness Syndrome (UWS) patients may be misdiagnosed. The aim of our study was to explore possible differences between the source powers within poly-modal cortices to differentiate Minimally Conscious State (MCS) from UWS. To this end, we recorded an electroencephalogram (EEG) during awake resting state and performed a Low-Resolution Brain Electromagnetic Tomography (LORETA), which is a 3D source localization method allowing the visualization of the most probable neuroanatomical generators of EEG differences. MCS and UWS patients showed significant variations concerning the frontal source power of delta-band, frontal and parietal of theta, parietal and occipital of alpha, central of beta, and parietal of gamma, in correlation with the Coma Recovery Scale-Revised (CRS-R) score. The alpha-band was the most significant LORETA data correlating with the consciousness level. In addition, we observed a significant correlation between central beta-peaks and the motor abilities and a dissociation between theta and gamma bands within parietal regions. Our findings suggest that LORETA analysis may be useful in DOC differential diagnosis since distinct neurophysiological correlates in some UWS patients could be used to assess deeper the residual cerebral activity of brain areas responsible for covert awareness.

  11. Jet and electromagnetic tomography (JET) of extreme phases of matter in heavy-ion collisions

    SciTech Connect

    Heinz, Ulrich

    2015-08-31

    The Ohio State University (OSU) group contributed to the deliverables of the JET Collaboration three major products: 1. The code package iEBE-VISHNU for modeling the dynamical evolution of the soft medium created in relativistic heavy-ion collisions, from its creation all the way to final freeze-out using a hybrid approach that interfaces a free-streaming partonic pre-equilbrium stage with a (2+1)-dimensional viscous relativistic fluid dynamical stage for the quark-gluon plasma (QGP) phase and the microscopic hadron cascade UrQMD for the hadronic rescattering and freeze-out stage. Except for UrQMD, all dynamical evolution components and interfaces were developed at OSU and tested and implemented in collaboration with the Duke University group. 2. An electromagnetic radiation module for the calculation of thermal photon emission from the QGP and hadron resonance gas stages of a heavy-ion collision, with emission rates that have been corrected for viscous effects in the expanding medium consistent with the bulk evolution. The electromagnetic radiation module was developed under OSU leadership in collaboration with the McGill group and has been integrated in the iEBE-VISHNU code package. 3. An interface between the Monte Carlo jet shower evolution and hadronization codes developed by the Wayne State University (WSU), McGill and Texas A&M groups and the iEBE-VISHNU bulk evolution code, for performing jet quenching and jet shape modification studies in a realistically modeled evolving medium that was tuned to measured soft hadron data. Building on work performed at OSU for the theoretical framework used to describe the interaction of jets with the medium, initial work on the jet shower Monte Carlo was started at OSU and moved to WSU when OSU Visiting Assistant Professor Abhijit Majumder accepted a tenure track faculty position at WSU in September 2011. The jet-hydro interface was developed at OSU and WSU and tested and implemented in collaboration with the McGill, Texas

  12. The impact of lower induction values of 50 Hz external electromagnetic fields on in vitro T lymphocyte adherence capabilities.

    PubMed

    Coček, Aleš; Hahn, Aleš; Mártonová, Jana; Ambruš, Miloslav; Dohnalová, Alena; Nedbalová, Martina; Jandová, Anna

    2012-06-01

    Our research thus far has concerned the impact of external electromagnetic fields (50 Hz) and low (0.01-10 mT) induction on adherence capabilities of T lymphocytes obtained from the blood of patients with head and neck tumors. We know that the in vitro adherence capability of T lymphocytes towards surfaces in cancer patients is less than that of control. Previously, we have found that exposure to electromagnetic fields (50 Hz/0.01-10 mT) increases the capability of T lymphocytes, in larynx/pharynx cancer patients, to adhere in vitro to surfaces, achieving almost physiological values, in not only pre-treatment patients but also those receiving treatment in the course of follow-up. The capability of T lymphocytes in controls (voluntary blood donors) to adhere to surfaces was also increased (50 Hz/0.01-0.5 mT). The present study concentrates on the significance of the level of electromagnetic field induction in order to determine whether low induction values can restore T lymphocytes adherence capabilities. Testing a subset of 20 patients showed a statistically significant difference (p<0.05) in the in vitro adherence capacity of T lymphocytes between both 0.01 and 0.05, and 0.1 mT induction levels. In the control group (patients diagnosed with chronic sensorineural hearing loss) there was even a statistically significant difference between induction values of 0.05 and 0.01 mT. A statistically significant difference (p<0.05) was also achieved with induction levels of 1 and 10 mT compared to 0.5, 0.1, and 0.05 mT, respectively. Therefore, we concluded that lower induction values resulted in a more biologically significant response.

  13. Estimation of soil salinity by using Markov Chain Monte Carlo simulation for multi-configuration electromagnetic induction measurements

    NASA Astrophysics Data System (ADS)

    Jadoon, K. Z.; Altaf, M. U.; McCabe, M. F.; Hoteit, I.; Moghadas, D.

    2014-12-01

    In arid and semi-arid regions, soil salinity has a major impact on agro-ecosystems, agricultural productivity, environment and sustainability. High levels of soil salinity adversely affect plant growth and productivity, soil and water quality, and may eventually result in soil erosion and land degradation. Being essentially a hazard, it's important to monitor and map soil salinity at an early stage to effectively use soil resources and maintain soil salinity level below the salt tolerance of crops. In this respect, low frequency electromagnetic induction (EMI) systems can be used as a noninvasive method to map the distribution of soil salinity at the field scale and at a high spatial resolution. In this contribution, an EMI system (the CMD Mini-Explorer) is used to estimate soil salinity using a Bayesian approach implemented via a Markov chain Monte Carlo (MCMC) sampling for inversion of multi-configuration EMI measurements. In-situ and EMI measurements were conducted across a farm where Acacia trees are irrigated with brackish water using a drip irrigation system. The electromagnetic forward model is based on the full solution of Maxwell's equation, and the subsurface is considered as a three-layer problem. In total, five parameters (electrical conductivity of three layers and thickness of top two layers) were inverted and modeled electrical conductivities were converted into the universal standard of soil salinity measurement (i.e. using the method of electrical conductivity of a saturated soil paste extract). Simulation results demonstrate that the proposed scheme successfully recovers soil salinity and reduces the uncertainties in the prior estimate. Analysis of the resulting posterior distribution of parameters indicates that electrical conductivity of the top two layers and the thickness of the first layer are well constrained by the EMI measurements. The proposed approach allows for quantitative mapping and monitoring of the spatial electrical conductivity

  14. A novel angular acceleration sensor based on the electromagnetic induction principle and investigation of its calibration tests.

    PubMed

    Zhao, Hao; Feng, Hao

    2013-08-12

    An angular acceleration sensor can be used for the dynamic analysis of human and joint motions. In this paper, an angular acceleration sensor with novel structure based on the principle of electromagnetic induction is designed. The method involves the construction of a constant magnetic field by the excitation windings of sensor, and the cup-shaped rotor that cut the magnetic field. The output windings of the sensor generate an electromotive force, which is directly proportional to the angular acceleration through the electromagnetic coupling when the rotor has rotational angular acceleration. The mechanical structure and the magnetic working circuit of the sensor are described. The output properties and the mathematical model including the transfer function and state-space model of the sensor are established. The asymptotical stability of the sensor when it is working is verified by the Lyapunov Theorem. An angular acceleration calibration device based on the torsional pendulum principle is designed. The method involves the coaxial connection of the angular acceleration sensor, torsion pendulum and a high-precision angle sensor, and then an initial external force is applied to the torsion pendulum to produce a periodic damping angle oscillation. The angular acceleration sensor and the angle sensor will generate two corresponding electrical signals. The sensitivity coefficient of the angular acceleration sensor can be obtained after processing these two-channel signals. The experiment results show that the sensitivity coefficient of the sensor is about 17.29 mv/Krad·s2. Finally, the errors existing in the practical applications of the sensor are discussed and the corresponding improvement measures are proposed to provide effective technical support for the practical promotion of the novel sensor.

  15. Study of the influence of the plastic casing on the electromagnetic induction response of a buried landmine

    NASA Astrophysics Data System (ADS)

    Das, Y.

    2008-04-01

    Most studies of the electromagnetic induction (EMI) response of a low-metal landmine buried in soil ignore any influence that the plastic casing may have on such response. In most cases such treatment is adequate since only the metal components of a landmine are expected to contribute to such a response. However, when the landmine is buried in a soil that has significant conductivity and/or magnetic susceptibility, the electromagnetic void created by the casing may have an influence on the EMI response of the landmine. That possibility is investigated using a simple analytical model and an experiment. A sphere is chosen as a simple prototype for the small metal parts in low-metal landmines, and a concentric spherical shell, made of foamed polystyrene, encasing the sphere is used to represent the plastic landmine body. The time-domain EMI response is measured using a purpose-designed system based on a modified Schiebel AN19/2 metal detector. Responses of the metallic sphere, the polystyrene shell and the metal-polystyrene composite target are measured with the targets buried in magnetic soil half-spaces. The particular soil type for which data are presented in this paper is Cambodian "laterite" with dispersive magnetic susceptibility, which serves as a good model for soils that are known to affect the performance of metal detectors. The metal sphere used has a diameter of 0.0254 m and is made of 6061-T6 aluminum, and the polystyrene shell has an outer diameter of 0.15 m. For the specific soil and targets used, theoretical results show that a small effect on the time-domain response is expected from the presence of the polystyrene casing. Experimental results confirm this for the case of the buried polystyrene shell. However the small difference in the example of the composite target is masked by experimental errors.

  16. Two-axis polydimethylsiloxane-based electromagnetic microelectromechanical system scanning mirror for optical coherence tomography

    NASA Astrophysics Data System (ADS)

    Kim, Sehui; Lee, Changho; Kim, Jin Young; Kim, Jeehyun; Lim, Geunbae; Kim, Chulhong

    2016-10-01

    Compact size and fast imaging abilities are key requirements for the clinical implementation of an optical coherence tomography (OCT) system. Among the various small-sized technology, a microelectromechanical system (MEMS) scanning mirror is widely used in a miniaturized OCT system. However, the complexities of conventional MEMS fabrication processes and relatively high costs have restricted fast clinical translation and commercialization of the OCT systems. To resolve these problems, we developed a two-axis polydimethylsiloxane (PDMS)-based MEMS (2A-PDMS-MEMS) scanning mirror through simple processes with low costs. It had a small size of 15×15×15 mm3, was fast, and had a wide scanning range at a low voltage. The AC/DC responses were measured to evaluate the performance of the 2A-PDMS-MEMS scanning mirror. The maximum scanning angles were measured as ±16.6 deg and ±11.6 deg along the X and Y axes, respectively, and the corresponding field of view was 29.8 mm×20.5 mm with an optical focal length of 50 mm. The resonance frequencies were 82 and 57 Hz along the X and Y axes, respectively. Finally, in vivo B-scan and volumetric OCT images of human fingertips and palms were successfully acquired using the developed SD-OCT system based on the 2A-PDMS-MEMS scanning mirror.

  17. On recovering distributed IP information from inductive source time domain electromagnetic data

    NASA Astrophysics Data System (ADS)

    Kang, Seogi; Oldenburg, Douglas W.

    2016-10-01

    We develop a procedure to invert time domain induced polarization (IP) data for inductive sources. Our approach is based upon the inversion methodology in conventional electrical IP (EIP), which uses a sensitivity function that is independent of time. However, significant modifications are required for inductive source IP (ISIP) because electric fields in the ground do not achieve a steady state. The time-history for these fields needs to be evaluated and then used to define approximate IP currents. The resultant data, either a magnetic field or its derivative, are evaluated through the Biot-Savart law. This forms the desired linear relationship between data and pseudo-chargeability. Our inversion procedure has three steps: (1) Obtain a 3-D background conductivity model. We advocate, where possible, that this be obtained by inverting early-time data that do not suffer significantly from IP effects. (2) Decouple IP responses embedded in the observations by forward modelling the TEM data due to a background conductivity and subtracting these from the observations. (3) Use the linearized sensitivity function to invert data at each time channel and recover pseudo-chargeability. Post-interpretation of the recovered pseudo-chargeabilities at multiple times allows recovery of intrinsic Cole-Cole parameters such as time constant and chargeability. The procedure is applicable to all inductive source survey geometries but we focus upon airborne time domain EM (ATEM) data with a coincident-loop configuration because of the distinctive negative IP signal that is observed over a chargeable body. Several assumptions are adopted to generate our linearized modelling but we systematically test the capability and accuracy of the linearization for ISIP responses arising from different conductivity structures. On test examples we show: (1) our decoupling procedure enhances the ability to extract information about existence and location of chargeable targets directly from the data maps

  18. Chemicals, metals, and pesticide pits waste unit low induction number electromagnetic survey

    SciTech Connect

    Cumbest, R.J.; Mohon, D.

    1995-06-01

    An electromagnetic survey was conducted at the Chemicals, Metals, and Pesticide Waste Unit to identify any buried metallic objects that may be present in the materials used to fill and cover the pits after removal of pit debris. The survey was conducted with a Geonics EM-31 Terrain Conductivity Meter along north - south oriented traverses with 5-ft station intervals to produce a 5-ft by 5-ft square grid node pattern. Both conductivity and in-phase components were measured at each station for vertical dipole orientation with the common axis of the dipoles in the north - south and east - west orientations. The conductivity data clearly show elevated conductivities (2.1 to 7.0 mS/m) associated with the material over the pits, as compared with the surrounding area that is characterized by lower conductivities (1 to 2 mS/m). This is probably the result of the higher clay content of the fill material relative to the surrounding area, which has a higher sand to clay ratio and the presence of a plastic cover beneath the fill that has probably trapped water. Many metal objects are present in the survey area including manhole covers, monitoring well heads, metal, signs, drain culverts, abandoned wells, and BP waste unit marker balls. AU of these exhibit associated conductivity and in-phase anomalies of various magnitude. In addition to these anomalies that can be definitely associated with surface sources, conductivity and in-phase anomalies are also present with no obvious surface source. These anomalies are probably indicative of subsurface buried metallic objects. A high concentration of these objects appears to be present in the southwest corner of the survey area.

  19. Numerical and Experimental Investigation on the Attenuation of Electromagnetic Waves in Unmagnetized Plasmas Using Inductively Coupled Plasma Actuator

    NASA Astrophysics Data System (ADS)

    Lin, Min; Xu, Haojun; Wei, Xiaolong; Liang, Hua; Song, Huimin; Sun, Quan; Zhang, Yanhua

    2015-10-01

    The attenuation of electromagnetic (EM) waves in unmagnetized plasma generated by an inductively coupled plasma (ICP) actuator has been investigated both theoretically and experimentally. A numerical study is conducted to investigate the propagation of EM waves in multilayer plasma structures which cover a square flat plate. Experimentally, an ICP actuator with dimensions of 20 cm×20 cm×4 cm is designed to produce a steady plasma slab. The attenuation of EM waves in the plasma generated by the ICP actuator is measured by a reflectivity arch test method at incident waves of 2.3 GHz and 10.1 GHz, respectively. A contrastive analysis of calculated and measured results of these incident wave frequencies is presented, which suggests that the experiment accords well with our theory. As expected, the plasma slab generated by the ICP actuator can effectively attenuate the EM waves, which may have great potential application prospects in aircraft stealth. supported by National Natural Science Foundation of China (Nos. 51276197, 11472306 and 11402301)

  20. Fast calculation of the sensitivity matrix in magnetic induction tomography by tetrahedral edge finite elements and the reciprocity theorem.

    PubMed

    Hollaus, K; Magele, C; Merwa, R; Scharfetter, H

    2004-02-01

    Magnetic induction tomography of biological tissue is used to reconstruct the changes in the complex conductivity distribution by measuring the perturbation of an alternating primary magnetic field. To facilitate the sensitivity analysis and the solution of the inverse problem a fast calculation of the sensitivity matrix, i.e. the Jacobian matrix, which maps the changes of the conductivity distribution onto the changes of the voltage induced in a receiver coil, is needed. The use of finite differences to determine the entries of the sensitivity matrix does not represent a feasible solution because of the high computational costs of the basic eddy current problem. Therefore, the reciprocity theorem was exploited. The basic eddy current problem was simulated by the finite element method using symmetric tetrahedral edge elements of second order. To test the method various simulations were carried out and discussed.

  1. Degradation of phenol wastewater by a new electromagnetic induction photo-catalytic reactor

    NASA Astrophysics Data System (ADS)

    Yuan, X. C.; Meng, Q. H.; Sun, J. Y.; Yan, Y.; Li, L.; Li, G. C.; Li, D.

    2016-08-01

    A new inductive photo-catalytic reactor was obtained by the alternative magnetic field and optical coupling, which was driven by AC supply. In the cylinder reactor, UV-LED lights with the wavelength of 375-380nm were evenly distributed, and the phenol solution was used as simulated wastewater. The effects of initial phenol concentration, pH, TiO2, H2O2, alternative magnetic frequency, current, and reaction time on the phenol degradation were investigated under an imposed alternative magnetic field. The optimized conditions and results were as follows: phenol concentrations of 15mg/L, pH of 7, H2O2 of 15μL, TiO2 of 0.18g and alternative magnetic frequency of 12 KHz and current of 2A. With these conditions, the phenol degradation ratio reached 47.1% in 1 h reaction time. The new reactor is very promising for the effective treatment of refractory organic pollutants.

  2. Three-Dimensional Electroencephalographic Changes on Low-Resolution Brain Electromagnetic Tomography (LORETA) During the Sleep Onset Period.

    PubMed

    Park, Doo-Heum; Ha, Jee Hyun; Ryu, Seung-Ho; Yu, Jaehak; Shin, Chul-Jin

    2015-10-01

    Electroencephalographic (EEG) patterns during sleep are markedly different from those measured during the waking state, but the process of falling asleep is not fully understood in terms of biochemical and neurophysiological aspects. We sought to investigate EEG changes that occur during the transitional period from wakefulness to sleep in a 3-dimensional manner to gain a better understanding of the physiological meaning of sleep for the brain. We examined EEG 3-dimensionally using LORETA (low-resolution electromagnetic tomography), to localize the brain region associated with changes that occur during the sleep onset period (SOP). Thirty-channel EEG was recorded in 61 healthy subjects. EEG power spectra and intracortical standardized LORETA were compared between 4 types of 30-second states, including the wakeful stage, transition stage, early sleep stage 1, and late sleep stage 1. Sleep onset began with increased delta and theta power and decreased alpha-1 power in the occipital lobe, and increased theta power in the parietal lobe. Thereafter, global reductions of alpha-1 and alpha-2 powers and greater increases of theta power in the occipito-parietal lobe occurred. As sleep became deeper in sleep stage 1, beta-2 and beta-3, powers decreased mainly in the frontal lobe and some regions of the parieto-temporo-limbic area. These findings suggest that sleep onset includes at least 3 steps in a sequential manner, which include an increase in theta waves in the posterior region of the brain, a global decrease in alpha waves, and a decrease in beta waves in the fronto-central area.

  3. Low-resolution brain electromagnetic tomography (LORETA) identifies brain regions linked to psychometric performance under modafinil in narcolepsy.

    PubMed

    Saletu, Michael; Anderer, Peter; Semlitsch, Heribert V; Saletu-Zyhlarz, Gerda Maria; Mandl, Magdalena; Zeitlhofer, Josef; Saletu, Bernd

    2007-01-15

    Low-resolution brain electromagnetic tomography (LORETA) showed a functional deterioration of the fronto-temporo-parietal network of the right hemispheric vigilance system in narcolepsy and a therapeutic effect of modafinil. The aim of this study was to determine the effects of modafinil on cognitive and thymopsychic variables in patients with narcolepsy and investigate whether neurophysiological vigilance changes correlate with cognitive and subjective vigilance alterations at the behavioral level. In a double-blind, placebo-controlled crossover design, EEG-LORETA and psychometric data were obtained during midmorning hours in 15 narcoleptics before and after 3 weeks of placebo or 400 mg modafinil. Cognitive investigations included the Pauli Test and complex reaction time. Thymopsychic/psychophysiological evaluation comprised drive, mood, affectivity, wakefulness, depression, anxiety, the Symptom Checklist 90 and critical flicker frequency. The Multiple Sleep Latency Test (MSLT) and the Epworth Sleepiness Scale (ESS) were performed too. Cognitive performance (Pauli Test) was significantly better after modafinil than after placebo. Concerning reaction time and thymopsychic variables, no significant differences were observed. Correlation analyses revealed that a decrease in prefrontal delta, theta and alpha-1 power correlated with an improvement in cognitive performance. Moreover, drowsiness was positively correlated with theta power in parietal and medial prefrontal regions and beta-1 and beta-2 power in occipital regions. A less significant correlation was observed between midmorning EEG LORETA and the MSLT; between EEG LORETA and the ESS, the correlation was even weaker. In conclusion, modafinil did not influence thymopsychic variables in narcolepsy, but it significantly improved cognitive performance, which may be related to medial prefrontal activity processes identified by LORETA.

  4. Localization of MDMA-induced brain activity in healthy volunteers using low resolution brain electromagnetic tomography (LORETA).

    PubMed

    Frei, E; Gamma, A; Pascual-Marqui, R; Lehmann, D; Hell, D; Vollenweider, F X

    2001-11-01

    3,4-Methylenedioxymethamphetamine (MDMA; 'Ecstasy') is a psychostimulant drug producing heightened mood and facilitated social communication. In animal studies, MDMA effects are primarily mediated by serotonin (5-HT), but also by dopamine (DA) and possibly noradrenaline (NA). In humans, however, the neurochemical and neurophysiological basis of acute MDMA effects remains unknown. The distribution of active neuronal populations after administration of a single dose of MDMA (1.7 mg/kg) or placebo was studied in 16 healthy, MDMA-naïve volunteers. Thirty-one-channel scalp EEGs during resting with open and closed eyes was analyzed in the different EEG frequency bands. Scalp maps of power showed significant, global differences between MDMA and placebo in both eye conditions and all frequency bands. Low resolution brain electromagnetic tomography (LORETA) was used to compute 3D, functional images of electric neuronal activity from the scalp EEG data. MDMA produced a widespread decrease of slow and medium frequency activity and an increase of fast frequency activity in the anterior temporal and posterior orbital cortex, concomitant with a marked enhancement of mood, emotional arousal and increased extraversion. This activation of frontotemporal areas indicates that the observed enhancement of mood and possibly the increased extroversion rely on modulation of limbic orbitofrontal and anterotemporal structures known to be involved in emotional processes. Comparison of the MDMA-specific EEG pattern with that of various 5-HT, DA, and NA agonists indicates that serotonin, noradrenaline, and, to a lesser degree, dopamine, contribute to the effects of MDMA on EEG, and possibly also on mood and behavior.

  5. Pulsed electromagnetic field affects intrinsic and endoplasmatic reticulum apoptosis induction pathways in MonoMac6 cell line culture.

    PubMed

    Kaszuba-Zwoinska, J; Chorobik, P; Juszczak, K; Zaraska, W; Thor, P J

    2012-10-01

    Current studies were aimed to elucidate influence of pulsed electromagnetic field stimulation on cell viability and apoptosis induction pathways. For the experimental model we have chosen monocytic cell line MonoMac6 and several apoptosis inducers with different mechanism of death induction like puromycin, colchicine, cyclophosphamide, minocycline and hydrogen peroxide. MonoMac6 cell line was grown at density 1x10(5) cells/well in 96-well culture plates. To induce cell death cell cultures were treated with different apoptosis inducers like puromycin, colchicine, cyclophosphamide, minocycline, hydrogen peroxide and at the same time with pulsed electromagnetic field 50 Hz, 45±5 mT (PEMF) for 4 hour per each stimulation, three times, in 24 hours intervals. Afterwards, cells were harvested for flow cytometry analysis of cell viability measured by annexin V-APC labeled and propidium iodide staining. Expression of apoptosis related genes was evaluated by semi quantitative reverse transcription (RT)-PCR assay. NuPAGE Novex Western blot analysis was carried out for apoptosis inducing factor (AIF) abundance in cytosolic and nuclear extracts of MonoMac6 cells. Puromycin, colchicine and minocycline activated cells and simultaneously treated with PEMF have shown out diminished percentage of annexinV positive (AnV+) cells comparing to controls without PEMF stimulation. MonaMac6 cells puromycin/colchicyne and PEMF treated were to a higher extent double stained (AnV+,PI+), which means increased late apoptotic as well as necrotic (PI+) cells, than non-stimulated controls. On the other hand, minocycline activated cells prior to PEMF treatment showed diminished amount of apoptotic and necrotic (annexin V, annexin V and propidium iodide, propidium iodide positive staining) cells. The opposite effect of PEMF on the percentage of annexin V positively stained cells has been achieved after treatment of MonoMac6 culture with cyclophoshamide and hydrogen peroxide. PEMF enhanced early

  6. A new time-domain approach for the electromagnetic induction problem in a three-dimensional heterogeneous earth

    NASA Astrophysics Data System (ADS)

    Hamano, Yozo

    2002-09-01

    We present a new time-domain approach to the forward modelling of 3-D electromagnetic induction in a heterogeneous conducting sphere excited by external and internal sources. This method utilizes the standard decomposition of the magnetic field into toroidal and poloidal parts, and spherical harmonic expansions of both the magnetic fields and the conductivity heterogeneity. Resulting induction equations for the spherical harmonics are solved simultaneously in the time domain. Coupling terms between the electromagnetic fields and the conductivity structure are re-expanded in spherical harmonics, so that the terms can be calculated by matrix multiplications at each time step of the computation. A finite difference approximation was used to solve the set of diffusion equations for the spherical harmonics up to degree 20. This method can be efficiently used to analyse transient geomagnetic variations to estimate the 3-D conductivity structure of the Earth. In order to validate the present approach, we solved an induction problem in simple four-layer mantle models, which consist of the surface layer (r= 6371 - 6351 km, σ=1 S m-1), the upper mantle (r= 6351 - 5971 km, σ= 0.01 S m-1), the transition layer (r= 5971 - 5671 km, σ= 0.01-1 S m-1), and the lower mantle (r= 5671 - 3481 km, σ= 1 S m-1). Conductivity heterogeneities are considered in the surface layer or the transition layer. For these models, temporal variations of the Gauss coefficients in response to a sudden application of P10-type external field were calculated, and the impulse response function of each harmonic component was obtained by differentiating the calculated variations with time. The response functions of the primary induced components, g10, have large initial values and monotonously decay with time. Changes of the decay rate reflect the radial distribution of the electrical conductivity. For the surface heterogeneous models, temporal variations of other secondary induced components have two

  7. Time series electromagnetic induction-log datasets, including logs collected through the 2014 water year in south Florida

    USGS Publications Warehouse

    Prinos, Scott T.; Valderrama, Robert

    2016-01-01

    Time series electromagnetic-induction log (TSEMIL) datasets are collected from PVC cased or uncased monitoring wells to evaluate changes in water conductivity over time. TSEMIL datasets consist of a series of individual electromagnetic-induction logs collected at a frequency of months or years that have been compiled into a dataset by eliminating small uniform offsets in bulk conductivity between logs likely caused by minor variations in calibration. At depths where water conductivity is not changing through time, each log is typically within about ±15 mS/m of the median of the dataset at any given depth, which is within the stated repeatability specifications of the probe (Mount Sopris Instrument Co., Inc., 2002). Though the offsets between logs are small (±15 mS/m), they obscure the ability to identify small but real changes in bulk conductivity resulting from changes in aquifer salinity. To create TSEMIL datasets, these offsets are removed by selecting a depth at which no changes are apparent from year to year, and by adjusting individual logs to the median of all logs at the selected depth. Generally, these depths are within the freshwater saturated part of the aquifer, well below the water table. Once the offsets have been removed there is generally only about ±2 to 3 mS/m of completely irregular variation between successive logs that cannot be removed. Even if perfect numerical alignment is achieved at one or two depths, the ±2 to 3 mS/m of random variation remains at other depths. Given these corrections, however, changes from year to year caused by saltwater intrusion are easier to identify. Detailed descriptions of how these corrections are applied are described in Prinos and others (2014) and Prinos and Valderrama (2015).TSEMIL datasets can be used to monitor changes in water conductivity throughout the full thickness of an aquifer, without the need for long open-interval wells, which have allowed, in some instances, vertical water flow within the

  8. A physical model for low-frequency electromagnetic induction in the near field based on direct interaction between transmitter and receiver electrons.

    PubMed

    Smith, Ray T; Jjunju, Fred P M; Young, Iain S; Taylor, Stephen; Maher, Simon

    2016-07-01

    A physical model of electromagnetic induction is developed which relates directly the forces between electrons in the transmitter and receiver windings of concentric coaxial finite coils in the near-field region. By applying the principle of superposition, the contributions from accelerating electrons in successive current loops are summed, allowing the peak-induced voltage in the receiver to be accurately predicted. Results show good agreement between theory and experiment for various receivers of different radii up to five times that of the transmitter. The limitations of the linear theory of electromagnetic induction are discussed in terms of the non-uniform current distribution caused by the skin effect. In particular, the explanation in terms of electromagnetic energy and Poynting's theorem is contrasted with a more direct explanation based on variable filament induction across the conductor cross section. As the direct physical model developed herein deals only with forces between discrete current elements, it can be readily adapted to suit different coil geometries and is widely applicable in various fields of research such as near-field communications, antenna design, wireless power transfer, sensor applications and beyond.

  9. A physical model for low-frequency electromagnetic induction in the near field based on direct interaction between transmitter and receiver electrons

    NASA Astrophysics Data System (ADS)

    Smith, Ray T.; Jjunju, Fred P. M.; Young, Iain S.; Taylor, Stephen; Maher, Simon

    2016-07-01

    A physical model of electromagnetic induction is developed which relates directly the forces between electrons in the transmitter and receiver windings of concentric coaxial finite coils in the near-field region. By applying the principle of superposition, the contributions from accelerating electrons in successive current loops are summed, allowing the peak-induced voltage in the receiver to be accurately predicted. Results show good agreement between theory and experiment for various receivers of different radii up to five times that of the transmitter. The limitations of the linear theory of electromagnetic induction are discussed in terms of the non-uniform current distribution caused by the skin effect. In particular, the explanation in terms of electromagnetic energy and Poynting's theorem is contrasted with a more direct explanation based on variable filament induction across the conductor cross section. As the direct physical model developed herein deals only with forces between discrete current elements, it can be readily adapted to suit different coil geometries and is widely applicable in various fields of research such as near-field communications, antenna design, wireless power transfer, sensor applications and beyond.

  10. A physical model for low-frequency electromagnetic induction in the near field based on direct interaction between transmitter and receiver electrons

    PubMed Central

    Smith, Ray T.; Jjunju, Fred P. M.; Young, Iain S.; Taylor, Stephen

    2016-01-01

    A physical model of electromagnetic induction is developed which relates directly the forces between electrons in the transmitter and receiver windings of concentric coaxial finite coils in the near-field region. By applying the principle of superposition, the contributions from accelerating electrons in successive current loops are summed, allowing the peak-induced voltage in the receiver to be accurately predicted. Results show good agreement between theory and experiment for various receivers of different radii up to five times that of the transmitter. The limitations of the linear theory of electromagnetic induction are discussed in terms of the non-uniform current distribution caused by the skin effect. In particular, the explanation in terms of electromagnetic energy and Poynting’s theorem is contrasted with a more direct explanation based on variable filament induction across the conductor cross section. As the direct physical model developed herein deals only with forces between discrete current elements, it can be readily adapted to suit different coil geometries and is widely applicable in various fields of research such as near-field communications, antenna design, wireless power transfer, sensor applications and beyond. PMID:27493580

  11. Development and First Results of a new Airplane Based Fixed Wing Electromagnetic Induction Sea Ice Thickness Sounder

    NASA Astrophysics Data System (ADS)

    Rabenstein, L.; Lobach, J.; Haas, C.

    2007-12-01

    Regular observation of Arctic and Antarctic sea ice thickness is of high importance for a better understanding of processes of climate change in polar regions. For regular and accurate observations of polar sea ice thickness a long range airborne device is necessary. Airborne electromagnetic induction (AEM) sounding was found to be an ideal method for accurate and wide area sea ice thickness measurements. As a consequence of five years of successful helicopter electromagnetic (HEM) sea ice thickness measurements and to overcome helicopter range restrictions, the Alfred Wegener Institute (AWI) constructed a new airplane based fixed wing EM system. The first test flights were carried out in 2006 over the North Sea and in April 2007 in Svalbard, where the system's performance was proven under arctic conditions. The system operates in frequency domain with 1990 Hz and a vertical coplanar coil configuration. Thus the system produces a horizontal dipole. The coils are mounted beneath the wings with a separation of 11.6 meters. The airplane, a Dornier 228, is also equipped with a laser altimeter to determine the altitude of the instrument with an accuracy of 2cm. The compensation of the transmitter signal at the receiver coil is done electronically. Flights over open sea are used for the calibration of the system, because the ocean functions as a homogeneous half space with well known conductivity. A data acquisition computer records four voltages with a sample rate of 10 Hz. These are the reference voltage of the transmitter, the compensated and raw receiver voltages and the compensation signal. The laser height is recorded with a sample rate of 100 Hz to account for surface roughness. EM instruments for sea ice thickness sounding should have a vertical resolution of 10cm but due to the electrical noise caused by the airplane engines this was not easy to achieve. To account for the noise a time average filter is used. Alternatively, in order to keep the original

  12. Estimation of soil salinity in a drip irrigation system by using joint inversion of multicoil electromagnetic induction measurements

    NASA Astrophysics Data System (ADS)

    Jadoon, Khan Zaib; Moghadas, Davood; Jadoon, Aurangzeb; Missimer, Thomas M.; Al-Mashharawi, Samir K.; McCabe, Matthew F.

    2015-05-01

    Low frequency electromagnetic induction (EMI) is becoming a useful tool for soil characterization due to its fast measurement capability and sensitivity to soil moisture and salinity. In this research, a new EMI system (the CMD mini-Explorer) is used for subsurface characterization of soil salinity in a drip irrigation system via a joint inversion approach of multiconfiguration EMI measurements. EMI measurements were conducted across a farm where Acacia trees are irrigated with brackish water. In situ measurements of vertical bulk electrical conductivity (σb) were recorded in different pits along one of the transects to calibrate the EMI measurements and to compare with the modeled electrical conductivity (σ) obtained by the joint inversion of multiconfiguration EMI measurements. Estimates of σ were then converted into the universal standard of soil salinity measurement (i.e., electrical conductivity of a saturated soil paste extract - ECe). Soil apparent electrical conductivity (ECa) was repeatedly measured with the CMD mini-Explorer to investigate the temperature stability of the new system at a fixed location, where the ambient air temperature increased from 26°C to 46°C. Results indicate that the new EMI system is very stable in high temperature environments, especially above 40°C, where most other approaches give unstable measurements. In addition, the distribution pattern of soil salinity is well estimated quantitatively by the joint inversion of multicomponent EMI measurements. The approach of joint inversion of EMI measurements allows for the quantitative mapping of the soil salinity distribution pattern and can be utilized for the management of soil salinity.

  13. Using the Electromagnetic Induction Method to Connect Spatial Vegetation Distributions with Soil Water and Salinity Dynamics on Steppe Grassland

    NASA Astrophysics Data System (ADS)

    Jiang, Z.; Li, X.; Wu, H.

    2014-12-01

    In arid and semi-arid areas, plant growth and productivity are obviously affected by soil water and salinity. But it is not easy to acquire the spatial and temporal dynamics of soil water and salinity by traditional field methods because of the heterogeneity in their patterns. Electromagnetic induction (EMI), for its rapid character, can provide a useful way to solve this problem. Grassland dominated by Achnatherum splendens is an important ecosystem near the Qinghai-Lake watershed on the Qinghai-Tibet Plateau in northwestern China. EMI surveys were conducted for electrical conductivity (ECa) at an intermediate habitat scale (a 60×60 m experimental area) of A. splendens steppe for 18 times (one day only for one time) during the 2013 growing season. And twenty sampling points were established for the collection of soil samples for soil water and salinity, which were used for calibration of ECa. In addition, plant species, biomass and spatial patterns of vegetation were also sampled. The results showed that ECa maps exhibited distinctly spatial differences because of variations in soil moisture. And soil water was the main factor to drive salinity patterns, which in turn affected ECa values. Moreover, soil water and salinity could explain 82.8% of ECa changes due to there was a significant correlation (P<0.01) between ECa, soil water and salinity. Furthermore, with higher ECa values closer to A. splendens patches at the experimental site, patterns of ECa images showed clearly temporal stability, which were extremely corresponding with the spatial pattern of vegetation. A. splendens patches that accumulated infiltrating water and salinity and thus changed long-term soil properties, which were considered as "reservoirs" and were deemed responsible for the temporal stability of ECa images. Hence, EMI could be an indicator to locate areas of decreasing or increasing of water and to reveal soil water and salinity dynamics through repeated ECa surveys.

  14. Digital Mapping of Soil Salinity and Crop Yield across a Coastal Agricultural Landscape Using Repeated Electromagnetic Induction (EMI) Surveys.

    PubMed

    Yao, Rongjiang; Yang, Jingsong; Wu, Danhua; Xie, Wenping; Gao, Peng; Jin, Wenhui

    2016-01-01

    Reliable and real-time information on soil and crop properties is important for the development of management practices in accordance with the requirements of a specific soil and crop within individual field units. This is particularly the case in salt-affected agricultural landscape where managing the spatial variability of soil salinity is essential to minimize salinization and maximize crop output. The primary objectives were to use linear mixed-effects model for soil salinity and crop yield calibration with horizontal and vertical electromagnetic induction (EMI) measurements as ancillary data, to characterize the spatial distribution of soil salinity and crop yield and to verify the accuracy of spatial estimation. Horizontal and vertical EMI (type EM38) measurements at 252 locations were made during each survey, and root zone soil samples and crop samples at 64 sampling sites were collected. This work was periodically conducted on eight dates from June 2012 to May 2013 in a coastal salt-affected mud farmland. Multiple linear regression (MLR) and restricted maximum likelihood (REML) were applied to calibrate root zone soil salinity (ECe) and crop annual output (CAO) using ancillary data, and spatial distribution of soil ECe and CAO was generated using digital soil mapping (DSM) and the precision of spatial estimation was examined using the collected meteorological and groundwater data. Results indicated that a reduced model with EMh as a predictor was satisfactory for root zone ECe calibration, whereas a full model with both EMh and EMv as predictors met the requirement of CAO calibration. The obtained distribution maps of ECe showed consistency with those of EMI measurements at the corresponding time, and the spatial distribution of CAO generated from ancillary data showed agreement with that derived from raw crop data. Statistics of jackknifing procedure confirmed that the spatial estimation of ECe and CAO exhibited reliability and high accuracy. A general

  15. Full-waveform modeling of Zero-Offset Electromagnetic Induction for Accurate Characterization of Subsurface Electrical Properties

    NASA Astrophysics Data System (ADS)

    Moghadas, D.; André, F.; Vereecken, H.; Lambot, S.

    2009-04-01

    Water is a vital resource for human needs, agriculture, sanitation and industrial supply. The knowledge of soil water dynamics and solute transport is essential in agricultural and environmental engineering as it controls plant growth, hydrological processes, and the contamination of surface and subsurface water. Increased irrigation efficiency has also an important role for water conservation, reducing drainage and mitigating some of the water pollution and soil salinity. Geophysical methods are effective techniques for monitoring the vadose zone. In particular, electromagnetic induction (EMI) can provide in a non-invasive way important information about the soil electrical properties at the field scale, which are mainly correlated to important variables such as soil water content, salinity, and texture. EMI is based on the radiation of a VLF EM wave into the soil. Depending on its electrical conductivity, Foucault currents are generated and produce a secondary EM field which is then recorded by the EMI system. Advanced techniques for EMI data interpretation resort to inverse modeling. Yet, a major gap in current knowledge is the limited accuracy of the forward model used for describing the EMI-subsurface system, usually relying on strongly simplifying assumptions. We present a new low frequency EMI method based on Vector Network Analyzer (VNA) technology and advanced forward modeling using a linear system of complex transfer functions for describing the EMI loop antenna and a three-dimensional solution of Maxwell's equations for wave propagation in multilayered media. VNA permits simple, international standard calibration of the EMI system. We derived a Green's function for the zero-offset, off-ground horizontal loop antenna and also proposed an optimal integration path for faster evaluation of the spatial-domain Green's function from its spectral counterpart. This new integration path shows fewer oscillations compared with the real path and permits to avoid the

  16. Digital Mapping of Soil Salinity and Crop Yield across a Coastal Agricultural Landscape Using Repeated Electromagnetic Induction (EMI) Surveys

    PubMed Central

    Yao, Rongjiang; Yang, Jingsong; Wu, Danhua; Xie, Wenping; Gao, Peng; Jin, Wenhui

    2016-01-01

    Reliable and real-time information on soil and crop properties is important for the development of management practices in accordance with the requirements of a specific soil and crop within individual field units. This is particularly the case in salt-affected agricultural landscape where managing the spatial variability of soil salinity is essential to minimize salinization and maximize crop output. The primary objectives were to use linear mixed-effects model for soil salinity and crop yield calibration with horizontal and vertical electromagnetic induction (EMI) measurements as ancillary data, to characterize the spatial distribution of soil salinity and crop yield and to verify the accuracy of spatial estimation. Horizontal and vertical EMI (type EM38) measurements at 252 locations were made during each survey, and root zone soil samples and crop samples at 64 sampling sites were collected. This work was periodically conducted on eight dates from June 2012 to May 2013 in a coastal salt-affected mud farmland. Multiple linear regression (MLR) and restricted maximum likelihood (REML) were applied to calibrate root zone soil salinity (ECe) and crop annual output (CAO) using ancillary data, and spatial distribution of soil ECe and CAO was generated using digital soil mapping (DSM) and the precision of spatial estimation was examined using the collected meteorological and groundwater data. Results indicated that a reduced model with EMh as a predictor was satisfactory for root zone ECe calibration, whereas a full model with both EMh and EMv as predictors met the requirement of CAO calibration. The obtained distribution maps of ECe showed consistency with those of EMI measurements at the corresponding time, and the spatial distribution of CAO generated from ancillary data showed agreement with that derived from raw crop data. Statistics of jackknifing procedure confirmed that the spatial estimation of ECe and CAO exhibited reliability and high accuracy. A general

  17. Using an electromagnetic induction sensor to estimate mass and depth of metal objects in a former battlefield

    NASA Astrophysics Data System (ADS)

    Smetryns, Marthe; Saey, Timothy; Note, Nicolas; Van Meirvenne, Marc

    2016-04-01

    Electromagnetic induction (EMI) sensors are used to perform a non-invasive geophysical survey of land, revealing electrical and magnetic properties of the soil. The technique is used for a variety of agricultural and archaeological purposes to map the soil and locate buried archaeological objects. Besides this, EMI sensors have proven effective to detect metal objects, like the metal remains of the First World War (WW1) in the Western part of Belgium. Most EMI sensors employed for metal detection rely on a single or multiple signal(s) coming from one receiver coil. In this research a multiple coil EMI sensor was used to survey several fields in the former war zone of WW1. This sensor, the DUALEM-21S sensor, consists of one transmitter and four receiver coils leading to four simultaneous measurements of the electric and magnetic properties of the soil. After mapping the fields, the possible metal objects were delineated based on a combination of all electrical measurements and safely excavated. By combining the signals from the different coil configurations, depth intervals for the buried metal objects were assigned to all selected anomalies. This way the metal objects could be located either within the plough layer (0 - 0.45 m), just underneath the plough layer (0.45 - 0.70 m) or deeper than 0.70 m under the surface. Finally, mass models were established within every depth interval to be able to predict the metal mass of every selected anomaly . This methodology was successfully validated in another field where several metal objects were buried. Finally, it was applied on several arable fields at a different location within the former WW1 front zone. Fields located in the centre of the former war zone contained more than 400 metal pieces per hectare, most of them just underneath the plough layer. Fields on the edge of the former war zone contained substantially less metal items per hectare. To conclude, the developed methodology can be employed to differentiate

  18. A 3D reconstruction algorithm for magneto-acoustic tomography with magnetic induction based on ultrasound transducer characteristics

    NASA Astrophysics Data System (ADS)

    Ma, Ren; Zhou, Xiaoqing; Zhang, Shunqi; Yin, Tao; Liu, Zhipeng

    2016-12-01

    In this study we present a three-dimensional (3D) reconstruction algorithm for magneto-acoustic tomography with magnetic induction (MAT-MI) based on the characteristics of the ultrasound transducer. The algorithm is investigated to solve the blur problem of the MAT-MI acoustic source image, which is caused by the ultrasound transducer and the scanning geometry. First, we established a transducer model matrix using measured data from the real transducer. With reference to the S-L model used in the computed tomography algorithm, a 3D phantom model of electrical conductivity is set up. Both sphere scanning and cylinder scanning geometries are adopted in the computer simulation. Then, using finite element analysis, the distribution of the eddy current and the acoustic source as well as the acoustic pressure can be obtained with the transducer model matrix. Next, using singular value decomposition, the inverse transducer model matrix together with the reconstruction algorithm are worked out. The acoustic source and the conductivity images are reconstructed using the proposed algorithm. Comparisons between an ideal point transducer and the realistic transducer are made to evaluate the algorithms. Finally, an experiment is performed using a graphite phantom. We found that images of the acoustic source reconstructed using the proposed algorithm are a better match than those using the previous one, the correlation coefficient of sphere scanning geometry is 98.49% and that of cylinder scanning geometry is 94.96%. Comparison between the ideal point transducer and the realistic transducer shows that the correlation coefficients are 90.2% in sphere scanning geometry and 86.35% in cylinder scanning geometry. The reconstruction of the graphite phantom experiment also shows a higher resolution using the proposed algorithm. We conclude that the proposed reconstruction algorithm, which considers the characteristics of the transducer, can obviously improve the resolution of the

  19. Interpretation and Prognostic Value of Positron Emission Tomography-Computed Tomography After Induction Chemotherapy With or Without Radiation in IIIA-N2 Non-small Cell Lung Cancer Patients Who Receive Curative Surgery.

    PubMed

    Kim, Sung Hwan; Lee, Jong Hoon; Lee, Guk Jin; Jeong, Songmi; Kwak, Yoo-Kang; Kim, Hoon-Kyo; Cho, Deog Gon; Park, Young Ha; Yu, Mina; Yoon, Sei Chul

    2015-06-01

    We evaluate the correlation of clinical staging on positron emission tomography-computed tomography (PET-CT) and pathologic staging and the prognostic value of PET-CT after induction chemotherapy in patients with locally advanced nonsmall cell lung cancer (NSCLC). We analyzed 42 cases of clinical stage IIIA-N2 NSCLC who receive 2 to 4 cycles of preoperative chemotherapy with or without radiation followed by curative resection. The maximum standard uptake value (SUVmax) of the suspected lesion on PET-CT was recorded. PET-CT findings after induction chemotherapy were compared with those of initial PET-CT and pathology after surgery. The accuracy of PET-CT in restaging of the primary tumor after induction chemotherapy was 50.0%. Eighteen (42.8%) of 42 patients were underestimated ycT stage, and 3 (7.1%) of 42 patients was overestimated ycT stage by PET-CT scan. The accuracy of PET-CT in restaging of the nodal disease was 71.4%. Six (14.3%) of 42 patients were underestimated ycN stage, and 6 (14.3%) of 42 patients were overestimated ycN stage as compared with pathologic staging. The 2-year overall survival (OS) and relapse-free survival (RFS) rate were 68.5% and 40.9%, respectively. Complete responders (ycT0N0M0) on PET-CT after induction chemotherapy had a significantly longer RFS time than did incomplete responders (28.3 vs 9.1 months, P = 0.021). Complete response on PET-CT after induction chemotherapy with or without radiation was a good prognosticator for RFS in stage IIIA-N2 NSCLC patients who received surgery. However, response evaluation on PET-CT after induction chemotherapy should be interpreted with caution due to its unacceptable accuracy.

  20. A new electromagnetic induction sensor using Vector Network Analyzer technology for accurate characterisation of soil electrical properties

    NASA Astrophysics Data System (ADS)

    André, F.; Lambot, S.; Moghadas, D.; Vereecken, H.

    2009-04-01

    Electromagnetic induction (EMI) has been widely used since the 70s to retrieve soil physico-chemical properties through the measurement of soil electrical conductivity. Soil electrical conductivity integrates several factors, mainly soil water content, salinity, clay content and temperature, and to a lesser extent, mineralogy, porosity, structure, cation exchange capacity, organic matter and bulk density. EMI has been shown to be useful for a wide range of environmental applications. EMI is non invasive and individual measurements are almost instantaneous, which permits to characterise large areas with fine spatial and/or temporal resolutions. Nevertheless, current EMI systems present some limitations. First, EMI usually operates at a single or at a limited number of fixed frequencies, which limits the information that can be retrieved from the subsurface. In addition, the calibration of existing commercial sensors is generally rather empirical and not accurate, which reduces the reliability of the data. Finally, the data processing techniques that are used to retrieve the soil electrical properties from EMI data often rely on strong simplifying assumptions with respect to wave propagation through the antenna-air-soil system. Performing EMI measurements with Vector Network Analyzer (VNA) technology would overcome a part of these limitations, allowing to work simultaneously at a wide range of frequencies and to readily perform robust calibrations, which are defined as an international standard. On that basis, we have developed a new algorithm for off-ground, zero-offset, frequency domain EMI based on full-waveform inverse modelling. The EMI forward model is based on a linear system of complex transfer functions for describing the loop antenna and its interactions with soil and an exact solution of Maxwell's equations for wave propagation in three-dimensional multilayered media. The approach has been validated in laboratory conditions for measurements at different

  1. Hardware and software design for an electromagnetic induction tomography (EMT) system for high contrast metal process applications

    NASA Astrophysics Data System (ADS)

    Ma, X.; Peyton, A. J.; Higson, S. R.; Lyons, A.; Dickinson, S. J.

    2006-01-01

    This paper presents the latest development of an EMT system designed for use in the metal production industry such as imaging molten steel flow profiles during continuous casting. The system that has been developed is based on a commercial data acquisition board residing in a PC host computer and programmed in the LabView graphical language. The paper reviews the new EMT hardware electronics and software. The noise effects and the detectability limits of the system are given in the paper followed by the system sensitivity map analysis. Optimal image reconstructions, including the simultaneous iterative reconstruction technique (SIRT) and non-iterative Tikhonov regularization, truncated singular value decomposition (TSVD), are also discussed and applied for the system. The system has been demonstrated in real time (10 frames s-1 for 5 kHz excitation) with test phantoms that represent typical metal flow profiles such as central, annular stream and multiple streams.

  2. Comparison of sea-ice thickness measurements under summer and winter conditions in the Arctic using a small electromagnetic induction device

    SciTech Connect

    Haas, C.; Eicken, H.; Miller, H.; Gerland, S.

    1997-05-01

    Drillhole-determined sea-ice thickness was compared with values derived remotely using a portable small-offset loop-loop steady state electromagnetic (EM) induction device during expeditions to Fram Strait and the Siberian Arctic, under typical winter and summer conditions. Simple empirical transformation equations are derived to convert measured apparent conductivity into ice thickness. Despite the extreme seasonal differences in sea-ice properties as revealed by ice core analysis, the transformation equations vary little for winter and summer. Thus, the EM induction technique operated on the ice surface in the horizontal dipole mode yields accurate results within 5 to 10% of the drillhole determined thickness over level ice in both seasons. The robustness of the induction method with respect to seasonal extremes is attributed to the low salinity of brine or meltwater filling the extensive pore space in summer. Thus, the average bulk ice conductivity for summer multiyear sea ice derived according to Archie`s law amounts to 23 mS/m compared to 3 mS/m for winter conditions. These mean conductivities cause only minor differences in the EM response, as is shown by means of 1-D modeling. However, under summer conditions the range of ice conductivities is wider. Along with the widespread occurrence of surface melt ponds and freshwater lenses underneath the ice, this causes greater scatter in the apparent conductivity/ice thickness relation. This can result in higher deviations between EM-derived and drillhole determined thicknesses in summer than in winter.

  3. Effect of inductive and capacitive coupling on the current-voltage characteristic and electromagnetic radiation from a system of Josephson junctions

    NASA Astrophysics Data System (ADS)

    Rahmonov, I. R.; Shukrinov, Yu. M.; Atanasova, P. Kh.; Zemlyanaya, E. V.; Bashashin, M. V.

    2017-01-01

    We have studied the current-voltage characteristic of a system of long Josephson junctions taking into account the inductive and capacitive coupling. The dependence of the average time derivative of the phase difference on the bias current and spatiotemporal dependences of the phase difference and magnetic field in each junction are considered. The possibility of branching of the current-voltage characteristic in the region of zero field step, which is associated with different numbers of fluxons in individual Josephson junctions, is demonstrated. The current-voltage characteristic of the system of Josephson junctions is compared with the case of a single junction, and it is shown that the observed branching is due to coupling between the junctions. The intensity of electromagnetic radiation associated with motion of fluxons is calculated, and the effect of coupling between junctions on the radiation power is analyzed.

  4. Feasibility study of a swept frequency electromagnetic probe (SWEEP) using inductive coupling for the determination of subsurface conductivity of the earth and water prospecting in arid regions

    NASA Technical Reports Server (NTRS)

    Latorraca, G. A.; Bannister, L. H.

    1974-01-01

    Techniques developed for electromagnetic probing of the lunar interior, and techniques developed for the generation of high power audio frequencies were combined to make practical a magnetic inductive coupling system for the rapid measurement of ground conductivity profiles which are helpful when prospecting for the presence and quality of subsurface water. A system which involves the measurement of the direction, intensity, and time phase of the magnetic field observed near the surface of the earth at a distance from a horizontal coil energized so as to create a field that penetrates the earth was designed and studied to deduce the conductivity and stratification of the subsurface. Theoretical studies and a rudimentary experiment in an arid region showed that the approach is conceptually valid and that this geophysical prospecting technique can be developed for the economical exploration of subterranean water resources.

  5. Stripe sensor tomography.

    PubMed

    Barbic, Mladen; Vltava, Lvcian; Barrett, Christopher P; Emery, Teresa H; Scherer, Axel

    2008-03-01

    We introduce a general concept of tomographic imaging for the case of an imaging sensor that has a stripelike shape. We first show that there is no difference, in principle, between two-dimensional tomography using conventional electromagnetic or particle radiation and tomography where a stripe sensor is mechanically scanned over a sample at a sequence of different angles. For a single stripe detector imaging, linear motion and angular rotation are required. We experimentally demonstrate single stripe sensor imaging principle using an elongated inductive coil detector. By utilizing an array of parallel stripe sensors that can be individually addressed, two-dimensional imaging can be performed with rotation only, eliminating the requirement for linear motion, as we also experimentally demonstrate with parallel coil array. We conclude that imaging with a stripe-type sensor of particular width and thickness (where the width is much larger than the thickness) is resolution limited only by the thickness (smaller parameter) of the sensor. We give examples of multiple sensor families where this imaging technique may be beneficial such as magnetoresistive, inductive, superconducting quantum interference device, and Hall effect sensors, and, in particular, discuss the possibilities of the technique in the field of magnetic resonance imaging.

  6. Einige Bemerkungen ueber die Erzeugung von Elektromagnetischen Wanderwellen und Stehenden Wellen zur Induktiven Plasmabeschleunigung (Some Comments Concerning the Generation of Traveling and Standing Electromagnetic Waves for Inductive Plasma Acceleration),

    DTIC Science & Technology

    Some comments are made for the generation of electromagnetic travelling and standing waves used for inductive plasma acceleration. Resulting from a...simple mathematical formulation the different features lead to a non-conventional method for travelling wave generation, which is compared with the

  7. Electromagnetic Induction of Zerovalent Iron (ZVI) Powder and Nanoscale Zerovalent Iron (NZVI) Particles Enhances Dechlorination of Trichloroethylene in Contaminated Groundwater and Soil: Proof of Concept.

    PubMed

    Phenrat, Tanapon; Thongboot, Thippawan; Lowry, Gregory V

    2016-01-19

    This study evaluates the concept of using zerovalent iron (ZVI) powder or nanoscale zerovalent iron (NZVI) particles in combination with a low frequency (150 kHz) AC electromagnetic field (AC EMF) to effectively remove trichloroethylene (TCE) from groundwater and saturated soils. ZVI and NZVI are ferromagnetic, which can induce heat under applied AC EMF. The heat generated by ZVI and NZVI induction can increase the rate of dechlorination, according to Arrhenius' equation, and increase the rate of TCE desorption from TCE-sorbed soil. Both dechlorination and TCE desorption enhance the overall TCE removal rate. We evaluated this novel concept in laboratory batch reactors. We found that both ZVI and NZVI can induce heat under applied AC EMF up to 120 °C in 20 min. Using ZVI and NZVI with AC EMF enhanced dechlorination of dissolved TCE (no soil) up to 4.96-fold. In addition to increasing the temperature by ZVI and NZVI induction heating, AC EMF increased intrinsic ZVI and NZVI reactivity, ostensibly due to accelerated corrosion, as demonstrated by the increased ORP. In a soil-water-TCE system, NZVI together with AC EMF thermally enhanced desorption of TCE from soil and increased the degradation of TCE up to 5.36-fold compared to the absence of AC EMF. For the first time, this study indicates the potential for ZVI and NZVI coupled with AC EMF as a combined remediation technique for increasing the rate and completeness of in situ cleanup of adsorbed phase contaminants.

  8. Multi-Sensor Systems Development for UXO Detection and Discrimination: Hand-Held Dual Magnetic/Electromagnetic Induction Sensor

    DTIC Science & Technology

    2008-04-01

    Induction Sensor David Wright, Hollis H. Bennett, Jr., Linda Peyman Dove, and Dwain K. Butler April 2008 E nv ir on m en ta l L ab or at or y...Quade Drive Cary, NC 27513-7400 Hollis H. Bennett, Jr., Linda Peyman Dove Environmental Laboratory U.S. Army Engineer Research and Development...NUMBER 5e. TASK NUMBER 6. AUTHOR(S) David Wright, Hollis H. Bennett, Jr., Linda Peyman Dove, and Dwain K. Butler 5f. WORK UNIT NUMBER 8

  9. Low-Resolution Electromagnetic Tomography (LORETA) of changed Brain Function Provoked by Pro-Dopamine Regulator (KB220z) in one Adult ADHD case

    PubMed Central

    Steinberg, Bruce; Blum, Kenneth; McLaughlin, Thomas; Lubar, Joel; Febo, Marcelo; Braverman, Eric R.; Badgaiyan, Rajendra D

    2016-01-01

    Attention Deficit-Hyperactivity Disorder (ADHD) often continues into adulthood. Recent neuroimaging studies found lowered baseline dopamine tone in the brains of affected individuals that may place them at risk for Substance Use Disorder (SUD). This is an observational case study of the potential for novel management of Adult ADHD with a non-addictive glutaminergic-dopaminergic optimization complex KB200z. Low-resolution electromagnetic tomography (LORETA) was used to evaluate the effects of KB220z on a 72-year-old male with ADHD, at baseline and one hour following administration. The resultant z-scores, averaged across Eyes Closed, Eyes Open and Working Memory conditions, increased for each frequency band, in the anterior, dorsal and posterior cingulate regions, as well as the right dorsolateral prefrontal cortex during Working Memory, with KB220z. These scores are consistent with other human and animal neuroimaging studies that demonstrated increased connectivity volumes in reward circuitry and may offer a new approach to ADHD treatment. However, larger randomized trials to confirm these results are required. PMID:27610420

  10. Induction of neuritogenesis in PC12 cells by a pulsed electromagnetic field via MEK-ERK1/2 signaling.

    PubMed

    Kudo, Tada-aki; Kanetaka, Hiroyasu; Shimizu, Yoshinaka; Abe, Toshihiko; Mori, Hitoshi; Mori, Kazumi; Suzuki, Eizaburo; Takagi, Toshiyuki; Izumi, Shin-ichi

    2013-01-01

    We examined the regulation of neuritogenesis by a pulsed electromagnetic field (PEMF) in rat PC12 pheochromocytoma cells, which can be induced to differentiate into neuron-like cells with elongated neurites by inducers such as nerve growth factor (NGF). Plated PC12 cells were exposed to a single PEMF (central magnetic flux density, 700 mT; frequency, 0.172 Hz) for up to 12 h per day and were then evaluated for extent of neuritogenesis or acetylcholine esterase (AChE) activity. To analyze the mechanism underlying the effect of the PEMF on the cells, its effects on intracellular signaling were examined using the ERK kinase (MEK) inhibitors PD098059 and U0126 (U0124 was used as a negative control for U0126). The number of neurite-bearing PC12 cells and AChE activity increased after PEMF exposure without the addition of other inducers of neuritogenesis. Additionally, PEMF exposure induced sustained activation of ERK1/2 in PC12 cells, but not in NR8383 rat alveolar macrophages. Furthermore, U0126 strongly inhibited PEMF-dependent ERK1/2 activation and neuritogenesis. The PEMF-dependent neuritogenesis was also suppressed by PD098059, but not U0124. These results suggest that PEMF stimulation independently induced neuritogenesis and that activation of MEK-ERK1/2 signaling was induced by a cell-type-dependent mechanism required for PEMF-dependent neuritogenesis in PC12 cells.

  11. Full-physics 3D heterogeneous simulations of electromagnetic induction fields on level and deformed sea ice

    SciTech Connect

    Samluk, Jesse P.; Geiger, Cathleen A.; Weiss, Chester J.; Kolodzey, James

    2015-10-01

    In this article we explore simulated responses of electromagnetic (EM) signals relative to in situ field surveys and quantify the effects that different values of conductivity in sea ice have on the EM fields. We compute EM responses of ice types with a three-dimensional (3-D) finite-volume discretization of Maxwell's equations and present 2-D sliced visualizations of their associated EM fields at discrete frequencies. Several interesting observations result: First, since the simulator computes the fields everywhere, each gridcell acts as a receiver within the model volume, and captures the complete, coupled interactions between air, snow, sea ice and sea water as a function of their conductivity; second, visualizations demonstrate how 1-D approximations near deformed ice features are violated. But the most important new finding is that changes in conductivity affect EM field response by modifying the magnitude and spatial patterns (i.e. footprint size and shape) of current density and magnetic fields. These effects are demonstrated through a visual feature we define as 'null lines'. Null line shape is affected by changes in conductivity near material boundaries as well as transmitter location. Our results encourage the use of null lines as a planning tool for better ground-truth field measurements near deformed ice types.

  12. Comparison of dipole-dipole resistivity and electromagnetic induction sounding over the Panther Canyon thermal anomaly, Grass Valley, Nevada

    SciTech Connect

    Wilt, M.; Beyer, J.H.; Goldstein, N.E.

    1980-05-01

    A comparison is made between the dipole-dipole resistivity method and electromagnetic sounding method based on surveys over a geothermal anomaly near Panther Canyon, Grass Valley, Nevada. Dipole-dipole data were taken in conjunction with large-scale geothermal studies in the area. Two orthogonal lines were measured over the heat flow anomaly and two-dimensional modeling was performed on the data. EM sounding data were taken with the Lawrence Berkeley Laboratory EM-60 system which is a large-moment, frequency-domain, horizontal-loop system. Relative to single 50-meter-radius transmitter coil, eight soundings were made with detectors at distances of 0.5 to 1.6 km from the loop. Interpreted results from the two surveys indicate substantial agreement in the depth to and thickness of a conductive zone that may be associated with the thermal anomaly. The dipole-dipole method is inherently better for resolving resistive basement beneath the conductive anomaly, and dc resistivity interpretation techniques are presently better to handle the complex two-dimensional geology. However, the EM method is far less labor intensive, requiring only one-third the field time for similar areal coverage.

  13. Effects of low-intensity AC and/or DC electromagnetic fields on cell attachment and induction of apoptosis

    SciTech Connect

    Blumenthal, N.C.; Ricci, J.; Breger, L.; Zychlinsky, A.; Solomon, H.; Chen, G.G.; Kuznetsov, D.; Dorfman, R.

    1997-05-01

    Rat tendon fibroblast (RTF) and rat bone marrow (RBM) osteoprogenitor cells were cultured and exposed to AC and/or DC magnetic fields in a triaxial Helmholtz coil in an incubator for up to 13 days. The AC fields were at 60 and 1,000 Hz and up to 0.25 mT peak to peak, and the DC fields were up to 0.25 mT. At various combinations of field strengths and frequencies, AC and/or DC fields resulted in extensive detachment of preattached cells and prevented the normal attachment of cells not previously attached to substrates. In addition, the fields resulted in altered cell morphologies. When RTF and RBM cells were removed from the fields after several days of exposure, they partially reattached and assumed more normal morphologies. An additional set of experiments described in the Appendix corroborates these findings and also shows that low-frequency EMF also initiates apoptosis, i.e., programmed cell death, at the onset of cell detachment. Taken together, these results suggest that the electromagnetic fields result in significant alterations in cell metabolism and cytoskeleton structure. Further work is required to determine the relative effect of the electric and magnetic fields on these phenomena. The research has implications for understanding the role of fields in affecting bone healing in fracture nonunions, in cell detachment in cancer metastasis, and in the effect of EMF on organisms generally.

  14. Full-physics 3D heterogeneous simulations of electromagnetic induction fields on level and deformed sea ice

    DOE PAGES

    Samluk, Jesse P.; Geiger, Cathleen A.; Weiss, Chester J.; ...

    2015-10-01

    In this article we explore simulated responses of electromagnetic (EM) signals relative to in situ field surveys and quantify the effects that different values of conductivity in sea ice have on the EM fields. We compute EM responses of ice types with a three-dimensional (3-D) finite-volume discretization of Maxwell's equations and present 2-D sliced visualizations of their associated EM fields at discrete frequencies. Several interesting observations result: First, since the simulator computes the fields everywhere, each gridcell acts as a receiver within the model volume, and captures the complete, coupled interactions between air, snow, sea ice and sea water asmore » a function of their conductivity; second, visualizations demonstrate how 1-D approximations near deformed ice features are violated. But the most important new finding is that changes in conductivity affect EM field response by modifying the magnitude and spatial patterns (i.e. footprint size and shape) of current density and magnetic fields. These effects are demonstrated through a visual feature we define as 'null lines'. Null line shape is affected by changes in conductivity near material boundaries as well as transmitter location. Our results encourage the use of null lines as a planning tool for better ground-truth field measurements near deformed ice types.« less

  15. Electromagnetic induction in a conductive strip in a medium of contrasting conductivity: application to VLF and MT above molten dykes

    NASA Astrophysics Data System (ADS)

    Davis, Paul M.

    2014-11-01

    Very low frequency (VLF) electromagnetic waves that penetrate conductive magma-filled dykes generate secondary fields on the surface that can be used to invert for dyke properties. The model used for the interpretation calculates currents induced in a conductive strip by an inducing field that decays exponentially with depth due to the conductivity of the surrounding medium. The differential equations are integrated to give an inhomogeneous Fredholm equation of the second kind with a kernel consisting of a modified Bessel function of the second kind. Numerical methods are typically used to solve for the induced currents in the strip. In this paper, we apply a modified Galerkin-Chebyshev method, which involves separating the kernel into source and field spectra and integrating the source terms to obtain a matrix equation for the unknown coefficients. The incident wave is expressed as a Chebyshev series. The modified Bessel function is separated into a logarithmic singularity and a non-singular remainder, both of which are expanded in complex Chebyshev polynomials. The Chebyshev coefficients for the remainder are evaluated using a fast Fourier transform, while the logarithmic term and incident field have analytic series. The deconvolution then involves a matrix inversion. The results depend on the ratio of strip-size to skin-depth. For infinite skin-depth and a singular conductivity distribution given by τ_0 a/√{a^2 - z^2 } (where τ0 is the conductance, a is the half-length and z the distance from the centre), Parker gives an analytic solution. We present a similar analytic series solution for the finite skin-depth case, where the size to skin depth ratio is small. Results are presented for different ratios of size to skin depth that can be compared with numerical solutions. We compare full-space and half-space solutions. A fit of the model to VLF data taken above a magma filled dykes in Hawaii and Mt Etna demonstrates that while properties such as depth to top

  16. Seismic velocity anisotropy and heterogeneity beneath the Mantle Electromagnetic and Tomography Experiment (MELT) region of the East Pacific Rise from analysis of P and S body waves

    USGS Publications Warehouse

    Hammond, W.C.; Toomey, D.R.

    2003-01-01

    We use teleseismic P and S delay times and shear wave splitting measurements to constrain isotropic and anisotropic heterogeneity in the mantle beneath the southern East Pacific Rise (SEPR). The data comprise 462 P and S delay times and 18 shear wave splitting observations recorded during the Mantle Electromagnetic and Tomography (MELT) Experiment. We estimate the mantle melt content (F) and temperature (T) variation from the isotropic velocity variation. Our results indicate that the maximum variation in F beneath our array is between zero and ???1.2%, and maximum variation in T is between zero and ???100 K. We favor an explanation having partial contributions from both T and F. We approximate the seismic anisotropy of the upper mantle with hexagonal symmetry, consistent with the assumption of two dimensionality of mantle flow. Our new tomographic technique uses a nonlinear inversion of P and slow S polarization delay times to simultaneously solve for coupled VP and VS heterogeneity throughout the model and for the magnitude of anisotropy within discrete domains. The domain dimensions and the dip of the anisotropy are fixed for each inversion but are varied in a grid search, obtaining the misfit of the models to the body wave delay data and to split times of vertically propagating S waves. The data misfit and the isotropic heterogeneity are sensitive to domain dimensions and dip of anisotropy. In a region centered beneath the SEPR the best average dip of the hexagonal symmetry axis is horizontal or dipping shallowly (<30??) west. Given the resolution of our data, a subaxial region characterized by vertically aligned symmetry axes may exist but is limited to be <80 km deep. We infer that the mantle flow beneath the SEPR is consistent with shallow asthenospheric return flow from the direction of the South Pacific superswell.

  17. Effects of the South American psychoactive beverage ayahuasca on regional brain electrical activity in humans: a functional neuroimaging study using low-resolution electromagnetic tomography.

    PubMed

    Riba, Jordi; Anderer, Peter; Jané, Francesc; Saletu, Bernd; Barbanoj, Manel J

    2004-01-01

    Ayahuasca, a South American psychotropic plant tea obtained from Banisteriopsis caapi and Psychotria viridis, combines monoamine oxidase-inhibiting beta-carboline alkaloids with N,N-dimethyltryptamine (DMT), a psychedelic agent showing 5-HT(2A) agonist activity. In a clinical research setting, ayahuasca has demonstrated a combined stimulatory and psychedelic effect profile, as measured by subjective effect self-assessment instruments and dose-dependent changes in spontaneous brain electrical activity, which parallel the time course of subjective effects. In the present study, the spatial distribution of ayahuasca-induced changes in brain electrical activity was investigated by means of low-resolution electromagnetic tomography (LORETA). Electroencephalography recordings were obtained from 18 volunteers after the administration of a dose of encapsulated freeze-dried ayahuasca containing 0.85 mg DMT/kg body weight and placebo. The intracerebral power density distribution was computed with LORETA from spectrally analyzed data, and subjective effects were measured by means of the Hallucinogen Rating Scale (HRS). Statistically significant differences compared to placebo were observed for LORETA power 60 and 90 min after dosing, together with increases in all six scales of the HRS. Ayahuasca decreased power density in the alpha-2, delta, theta and beta-1 frequency bands. Power decreases in the delta, alpha-2 and beta-1 bands were found predominantly over the temporo-parieto-occipital junction, whereas theta power was reduced in the temporomedial cortex and in frontomedial regions. The present results suggest the involvement of unimodal and heteromodal association cortex and limbic structures in the psychological effects elicited by ayahuasca.

  18. Emotion Regulation of Neuroticism: Emotional Information Processing Related to Psychosomatic State Evaluated by Electroencephalography and Exact Low-Resolution Brain Electromagnetic Tomography.

    PubMed

    Ikeda, Shunichiro; Mizuno-Matsumoto, Yuko; Canuet, Leonides; Ishii, Ryouhei; Aoki, Yasunori; Hata, Masahiro; Katsimichas, Themistoklis; Pascual-Marqui, Roberto D; Hayashi, Takuto; Okamoto, Eika; Asakawa, Tetsuya; Iwase, Masao; Takeda, Masatoshi

    2015-02-27

    Emotion regulation is the process that adjusts the type or amount of emotion when we experience an emotional situation. The aim of this study was to reveal quantitative changes in brain activity during emotional information processing related to psychosomatic states and to determine electrophysiological features of neuroticism. Twenty-two healthy subjects (mean age 25 years, 14 males and 8 females) were registered. Electroencephalography (EEG) was measured during an emotional audiovisual memory task under three conditions (neutral, pleasant and unpleasant sessions). We divided the subjects into two groups using the Cornell Medical Index (CMI): (CMI-I: control group, n = 10: CMI-II, III or IV: neuroticism group, n = 12). We analyzed the digital EEG data using exact low-resolution brain electromagnetic tomography (eLORETA) current source density (CSD) and functional connectivity analysis in several frequency bands (δ, θ, α, β, γ and whole band). In all subjects, bilateral frontal α CSD in the unpleasant session increased compared to the pleasant session, especially in the control group (p < 0.05). CSD of the neuroticism group was significantly higher than that of the control group in the full band at the amygdala and inferior temporal gyrus, and in the α band at the right temporal lobe (p < 0.05). Additionally, we found an increase in functional connectivity between the left insular cortex and right superior temporal gyrus in all subjects during the unpleasant session compared to the pleasant session (p < 0.05). In this study, using EEG analysis, we could find a novel cortical network related to brain mechanisms underlying emotion regulation. Overall findings indicate that it is possible to characterize neuroticism electrophysiologically, which may serve as a neurophysiological marker of this personality trait. © 2015 S. Karger AG, Basel.

  19. Comparing non contrast computerized tomography criteria versus dual X-ray absorptiometry as predictors of radio-opaque upper urinary tract stone fragmentation after electromagnetic shockwave lithotripsy.

    PubMed

    Hameed, Diaa A; Elgammal, Mohammed A; ElGanainy, Ehab O; Hageb, Adel; Mohammed, Khaled; El-Taher, Ahmed Mohamed; Mostafa, Mostafa Mohamed; Ahmed, Abdelfatah Ibrahim

    2013-11-01

    The objective of this study was to assess the value of dual X-ray absorptiometry (DXA) in comparison to non contrast computed tomography (NCCT) density as possible predictors of upper urinary tract stone disintegration by shock wave lithotripsy (SWL). This study included 100 consecutive patients, with solitary renal stone 0.5-2 cm or upper ureteral stone up to 1 cm. DXA to calculate stone mineral density (SMD) and stone mineral content (SMC) was done. NCCT was performed to measure Hounsfield units (HU). SWL was performed with an electromagnetic lithotripsy, plain X-ray documented disintegration after SWL. Successful treatment was defined as stone free or complete fragmentation after 1 or 2 sessions of SWL. The impact of patients age, sex, body mass index, stone laterality, location, volume, length, mean SMC and SMD, HU and Hounsfield density (HD), skin to stone distance (SSD) and number of shock waves were evaluated by univariate and multivariate analysis. Only 76 patients were available for follow-up. Success of disintegration was observed in 50 out of 76 patients (65.8 %). On multivariate analysis, SMC and number of shock wave were the significant independent factors affecting SWL outcome (p = 0.04 and p = 0.000, respectively). SMC as detected by DXA is a significant predictor of success of stone disintegration by SWL. SMC measured by DXA is more accurate than HU measured by CT. Patients with high stone mineral content (SMC greater than 0.65 g) should be directly offered another treatment option.

  20. Electromagnetic induction of nanoscale zerovalent iron particles accelerates the degradation of chlorinated dense non-aqueous phase liquid: Proof of concept.

    PubMed

    Phenrat, Tanapon; Kumloet, Itsaraphong

    2016-12-15

    In this study, a novel electromagnetically enhanced treatment concept is proposed for in situ remediation of a source zone of chlorinated dense non-aqueous phase liquid (DNAPL) that is slowly dissolved, causing contaminated groundwater for centuries. Here, we used polystyrene sulfonate (PSS)-modified nanoscale zerovalent iron (NZVI) particles (ferromagnetic) in combination with a low frequency (LF) (150 kHz) AC electromagnetic field (EMF) to accelerate the degradation of the DNAPLs via enhanced dissolution and reductive dechlorination. Trichloroethylene (TCE) and tetrachloroethylene (PCE) were used in a bench-scaled evaluation. The PSS-modified NZVI successfully targeted the DNAPL/water interface, as evidenced by the Pickering emulsion formation. Dechlorination of TCE- and PCE-DNAPL was measured by quantifying the by-product formation (acetylene, ethene, and ethane). Without magnetic induction heating (MIH) by LF EMF, PSS-modified NZVI transformed TCE- and PCE-DNAPL to ethene and ethane at the rate constants of 12.19 × 10(-3) and 1.00 × 10(-3) μmol/h/m(2), respectively, following pseudo zero-order reactions. However, four MIH cycles of PSS-NZVI increased the temperature up to 87 °C and increased the rate constants of TCE-DNAPL and PCE-DNAPL up to 14.58 and 58.01 times, respectively, in comparison to the dechlorination rate without MIH. Theoretical analysis suggested that the MIH of the PSS-modified NZVI enhanced the dechlorination of TCE- and PCE-DNAPL via the combination of the enhanced thermal dissolution of DNAPL, the effect of increasing the temperature on the rate constant (the Arrhenius equation), and the accelerated NZVI corrosion. Nevertheless, the effect of the Arrhenius equation was dominant. For the first time, this proof-of-concept study reveals the potential for using polyelectrolyte-modified NZVI coupled with LF EMF as a combined remediation technique for increasing the rate and completeness of in situ chlorinated DNAPL source remediation.

  1. Electromagnetic induction for improved target location and segregation using spatial point pattern analysis with applications to historic battlegrounds and UXO remediation

    NASA Astrophysics Data System (ADS)

    Pierce, Carl James, Jr.

    Remediation of unexploded ordnance (UXO) and prioritization of excavation procedures for archaeological artifacts using electromagnetic (EM) induction are studied in this dissertation. Lowering of the false alarm rates that require excavation and artifact excavation prioritization can reduce the costs associated with unnecessary procedures. Data were taken over 5 areas at the San Jacinto Battleground near Houston, Texas, using an EM-63 metal detection instrument. The areas were selected using the archaeological concepts of cultural and natural formation processes applied to what is thought to be areas that were involved in the 1836 Battle of San Jacinto. Innovative use of a Statistical Point Pattern Analysis (PPA) is employed to identify clustering of EM anomalies. The K-function uses point {x,y} data to look for possible clusters in relation to other points in the data set. The clusters once identified using K-function will be further examined for classification and prioritization using the Weighted K-function. The Weighted K-function uses a third variable such as millivolt values or time decay to aid in segregation and prioritization of anomalies present. Once the anomalies of interest are identified, their locations are determined using the Gi-Statistics Technique. The Gi*-Statistic uses the individual Cartesian{x, y} points as origin locations to establish a range of distances to other cluster points in the data set. The segregation and location of anomalies supplied by this analysis will have several benefits. Prioritization of excavations will narrow down what areas should be excavated first. Anomalies of interest can be located to guide excavation procedures within the areas surveyed. Knowing what anomalies are of greater importance than others will help to lower false alarm rates for UXO remediation or for archaeological artifact selection. Knowing significant anomaly location will reduce the number of excavations which will subsequently save time and money

  2. Characterization and high resolution mapping of soil hydrogeophysical properties from ground penetrating radar and electromagnetic induction data in a vineyard in southern France

    NASA Astrophysics Data System (ADS)

    Andre, F.; van Durmen, R.; Saussez, S.; van Leeuwen, C.; Moghadas, D.; Delvaux, B.; Vereecken, H.; Sebastien, L.

    2010-12-01

    Soil and climate are acknowledged to greatly affect vine growth and grape berry composition through their strong influence on vine water status. Over a limited area, climatic factors may be considered as rather homogeneous for a given vintage while soil characteristics may vary strongly over short distances. Therefore, detailed characterization of soil hydrogeophysical properties is of prime importance for the definition of optimal vineyard practices. In that respect, ground penetrating radar (GPR) and electromagnetic induction (EMI) are effective geophysical techniques for fast and non-invasive determination of shallow subsurface properties through the measurement of soil dielectric permittivity and electrical conductivity. Given contrasted sensitivities of GPR and EMI to soil electrical properties, combining measurements from both techniques allows to merge complementary information, thereby leading to more accurate quantitative characterisation of soil. Classical GPR and EMI data processing techniques for soil properties characterisation rely on strongly simplifying assumptions in the modelling of electromagnetic phenomena, leading to significant errors on the estimates and accounting for only a part of the data information content. We developed generalized multi-offset full-waveform approaches for modelling off-ground and on-ground GPR and EMI signals. GPR and EMI systems are modelled using sets of infinitesimal electric and magnetic dipoles, allowing us to properly describe the distribution of the scattered field when the subsurface is located in the near-field of the antenna. The antenna model is coupled with a three-dimensional Green’s function, corresponding to a specific solution of the Maxwell’s equations for wave propagation or diffusion in multilayered media. The approaches were applied in a vineyard in south of France (Saint-Emilion) over a 30-ha area characterized by strong spatial variations of soil types. Around 1 million GPR waveforms and 73

  3. Repeated electromagnetic induction measurements for mapping soil moisture at the field scale: validation with data from a wireless soil moisture monitoring network

    NASA Astrophysics Data System (ADS)

    Martini, Edoardo; Werban, Ulrike; Zacharias, Steffen; Pohle, Marco; Dietrich, Peter; Wollschläger, Ute

    2017-01-01

    Electromagnetic induction (EMI) measurements are widely used for soil mapping, as they allow fast and relatively low-cost surveys of soil apparent electrical conductivity (ECa). Although the use of non-invasive EMI for imaging spatial soil properties is very attractive, the dependence of ECa on several factors challenges any interpretation with respect to individual soil properties or states such as soil moisture (θ). The major aim of this study was to further investigate the potential of repeated EMI measurements to map θ, with particular focus on the temporal variability of the spatial patterns of ECa and θ. To this end, we compared repeated EMI measurements with high-resolution θ data from a wireless soil moisture and soil temperature monitoring network for an extensively managed hillslope area for which soil properties and θ dynamics are known. For the investigated site, (i) ECa showed small temporal variations whereas θ varied from very dry to almost saturation, (ii) temporal changes of the spatial pattern of ECa differed from those of the spatial pattern of θ, and (iii) the ECa-θ relationship varied with time. Results suggest that (i) depending upon site characteristics, stable soil properties can be the major control of ECa measured with EMI, and (ii) for soils with low clay content, the influence of θ on ECa may be confounded by changes of the electrical conductivity of the soil solution. Further, this study discusses the complex interplay between factors controlling ECa and θ, and the use of EMI-based ECa data with respect to hydrological applications.

  4. [The effects of pulsed electromagnetic fields on the induction of rat bone marrow mesenchymal stem cells to differentiate into cardiomyocytes-like cells in vitro].

    PubMed

    Feng, Xian; He, Xueling; Li, Kai; Wu, Wenchao; Liu, Xiaojing; Li, Liang

    2011-08-01

    The aim of this study is to investigate the effects of pulsed electromagnetic fields (PEMFs) on the induction of rat bone marrow mesenchymal stem cells (rBMSCs) to differentiate into cardiomyocytes-like cells in vitro. rBMSCs were randomly divided into PEMFs groups, 5-Azacytidine (5-Aza) groups and control groups. PEMFs groups were exposed to 50 Hz, 1 mT PEMFs for 30 min every day, lasting for 10 d, 15 d and 20 d, respectively. 5-Aza groups were induced by 10 micromol/L 5-Aza for 1 day, then the medium was changed to complete medium without 5-Aza. And control groups were only cultured with complete medium, rBMSCs growth status and morphological features were observed by inverted phase microscope every day. The mRNA expressions of cardiac troponin T (TNNT2) and alpha-actinin (ACTN2) were determined by Real-Time PCR. The results showed that rBMSCs were spindle, polygon or fusiform in control groups. The cells gradually got longer and grew close together after being stimulated by PEMFs and 5-Aza, and with the extension of induction time, the tendency became obvious. At 20th day after PEMFs or 5-Aza treatment, rBMSCs gathered like a long chain, got much longer obviously at the high magnification, and some of them even fused with their neighbors. Compared with control groups, the levels of TNNT2 mRNA expression in 5-Aza groups were 19.40 fold (P < 0.01), 21.02 fold (P < 0.01) and 2.38 fold at 10 d, 15 d, 20 d and the levels of ACTN2 mRNA expression in 5-Aza groups were 6.64 fold (P < 0.01), 6.67 fold (P < 0.01) and 0.76 fold at 10 d, 15 d, 20 d. However, the levels of TNNT2 mRNA expression in PEMFs groups were 15.78 fold (P < 0.01), 6.73 fold (P < 0.05) and 2.73 fold (P < 0.01) of control groups at 10 d, 15 d, 20 d and the levels of ACTN2 mRNA expression in PEMFs groups were 4.93 fold (P < 0.01), 1.89 fold and 0.64 fold, respectively. Compared with 5-Aza groups, the levels of TNNT2 mRNA expression in PEMFs groups were 0.81 fold, 0.32 fold (P < 0.01) and 1.15 fold at 10

  5. Single-Step 3-D Image Reconstruction in Magnetic Induction Tomography: Theoretical Limits of Spatial Resolution and Contrast to Noise Ratio

    PubMed Central

    Hollaus, Karl; Rosell-Ferrer, Javier; Merwa, Robert

    2006-01-01

    Magnetic induction tomography (MIT) is a low-resolution imaging modality for reconstructing the changes of the complex conductivity in an object. MIT is based on determining the perturbation of an alternating magnetic field, which is coupled from several excitation coils to the object. The conductivity distribution is reconstructed from the corresponding voltage changes induced in several receiver coils. Potential medical applications comprise the continuous, non-invasive monitoring of tissue alterations which are reflected in the change of the conductivity, e.g. edema, ventilation disorders, wound healing and ischemic processes. MIT requires the solution of an ill-posed inverse eddy current problem. A linearized version of this problem was solved for 16 excitation coils and 32 receiver coils with a model of two spherical perturbations within a cylindrical phantom. The method was tested with simulated measurement data. Images were reconstructed with a regularized single-step Gauss–Newton approach. Theoretical limits for spatial resolution and contrast/noise ratio were calculated and compared with the empirical results from a Monte-Carlo study. The conductivity perturbations inside a homogeneous cylinder were localized for a SNR between 44 and 64 dB. The results prove the feasibility of difference imaging with MIT and give some quantitative data on the limitations of the method. PMID:17031597

  6. An Electromagnetic Induction Flashlight Experiment

    ERIC Educational Resources Information Center

    Alden, Emily; Kennedy, Mark; Lorenzon, Wolfgang; Smith, Warren

    2007-01-01

    In the last several years, the electronics industry has released hand generator-powered flashlights, which are advertised as the end of battery-powered flashlights. This has become possible because of recent advances in capacitor, magnet, and LED technology. Nevertheless, the physics behind these flashlights is fairly simple.

  7. Theory of grazing electromagnetic induction

    NASA Astrophysics Data System (ADS)

    Binder, P.-M.; Guerrero, Juan F.

    2016-11-01

    We calculate the emf produced when a square loop grazes a point dipole, moving parallel to it. To do this we combine analytical and numerical work. An emf signal with a three-peak structure which was previously observed is thus explained, while other signal forms are predicted.

  8. Electromagnetic Induction with Neodymium Magnets

    ERIC Educational Resources Information Center

    Wood, Deborah; Sebranek, John

    2013-01-01

    In April 1820, Hans Christian Ørsted noticed that the needle of a nearby compass deflected briefly from magnetic north each time the electric current of the battery he was using for an unrelated experiment was turned on or off. Upon further investigation, he showed that an electric current flowing through a wire produces a magnetic field. In 1831…

  9. Magnetoacoustic tomography with magnetic induction for high-resolution bioimepedance imaging through vector source reconstruction under the static field of MRI magnet

    SciTech Connect

    Mariappan, Leo; Hu, Gang; He, Bin

    2014-02-15

    Purpose: Magnetoacoustic tomography with magnetic induction (MAT-MI) is an imaging modality to reconstruct the electrical conductivity of biological tissue based on the acoustic measurements of Lorentz force induced tissue vibration. This study presents the feasibility of the authors' new MAT-MI system and vector source imaging algorithm to perform a complete reconstruction of the conductivity distribution of real biological tissues with ultrasound spatial resolution. Methods: In the present study, using ultrasound beamformation, imaging point spread functions are designed to reconstruct the induced vector source in the object which is used to estimate the object conductivity distribution. Both numerical studies and phantom experiments are performed to demonstrate the merits of the proposed method. Also, through the numerical simulations, the full width half maximum of the imaging point spread function is calculated to estimate of the spatial resolution. The tissue phantom experiments are performed with a MAT-MI imaging system in the static field of a 9.4 T magnetic resonance imaging magnet. Results: The image reconstruction through vector beamformation in the numerical and experimental studies gives a reliable estimate of the conductivity distribution in the object with a ∼1.5 mm spatial resolution corresponding to the imaging system frequency of 500 kHz ultrasound. In addition, the experiment results suggest that MAT-MI under high static magnetic field environment is able to reconstruct images of tissue-mimicking gel phantoms and real tissue samples with reliable conductivity contrast. Conclusions: The results demonstrate that MAT-MI is able to image the electrical conductivity properties of biological tissues with better than 2 mm spatial resolution at 500 kHz, and the imaging with MAT-MI under a high static magnetic field environment is able to provide improved imaging contrast for biological tissue conductivity reconstruction.

  10. New Perspective on Classical Electromagnetism

    DTIC Science & Technology

    2013-04-01

    R. Feynman , R. Leighton, and M. Sands, The Feynman Lectures in Physics vol II (Addison-Wesley, Reading, MA, 1964). 6. W.K.H. Panofsky and M...of the basics of classical electromagnetism is provided by recognizing a previously overlooked law of induction as well as the physical reality of the...classical electromagnetism is provided by recognizing a previously overlooked law of induction as well as the physical reality of the vector potential

  11. Assessing the value of multi-receiver low-frequency electromagnetic-induction (EMI) measurement for assessing variation in soil moisture content in field experiments with winter wheat (Triticum aestivum)

    NASA Astrophysics Data System (ADS)

    Shanahan, Peter; Binley, Andrew; Dodd, Ian; Whalley, Richard; Watts, Chris; Ashton, Rhys; Ober, Eric

    2014-05-01

    In large plant breeding field trials with multiple genotypes, measuring soil water status (an indicator of crop water uptake) by conventional techniques (e.g. core extraction and penetration resistance) is limited by the cost and effort needed to achieve sufficient replication to apply robust statistical analysis. Geophysical methods may provide a more cost-effective means of more assessing valuable information about soil water status for such studies. We present here results from a field experiment using geophysical techniques for remote mapping of soil water content on sandy loam and silt loam soils in spring/summer 2013 in the UK. The aim of the study was to assess electromagnetic-induction (EMI) conductivity measurements for sensitivity to variations in shallow soil electrical properties and the spatial and temporal mapping of soil water. The CMD Mini-Explorer (GF Instruments) operates with three receiver coils at fixed distances from a transmitter coil (0.32 m, 0.71 m, 1.2 m). Measurement of magnetic field quadrature in horizontal coplanar (HC) and vertical coplanar (VC) of the three receiver coils provides six depths of investigation for the given coil spacing cumulative sensitivities. At the two field sites the instrument was applied to measuring apparent electrical conductivity (ECa) below 7.0 x 1.8 m plots consisting of 23 rain fed winter wheat cultivars and bare soil fallow control plots. These plots were sown in March 2013 and organised into a randomised block design. Electrical resistivity tomography (ERT) surveys along 15 m transects were also conducted at the two sites in order to compare EMI measured ECa. Our results show that progressive soil drying at both sites due to crop uptake significantly decreased (p<0.05) soil ECa. The difference in soil ECa as a result of water uptake between cultivars was found to be significant (p<0.05) from one of the coil configurations (coil spacing 1.8m in HC mode), and only at the silty loam site (no significant

  12. Field test of a multi-frequency electromagnetic induction sensor for the study of soil moisture in different land-soil units

    NASA Astrophysics Data System (ADS)

    Calamita, Giuseppe; Onorati, Beniamino; Perrone, Angela; Manfreda, Salvatore; Brocca, Luca

    2015-04-01

    The crucial role of the soil moisture (SM) in a number of natural processes that act at different spatial and temporal scales has been largely recognized by the scientific community. Although the most used ground-based techniques for SM measurement (i.e. the Thermo-gravimentric, Time Domain Reflectometry (TDR) probes, Capacitance sensors, Neutron-moisture meters (NMM)) proved to be accurate and permit to acquire data at a high temporal resolution, they still remain invasive and punctual. As the size of the area of interest grows, these methods reveal applicability limitations that have been only partially overcome with the coming of the distributed sensor networks. During last decade, it has been pointed out that an improved understanding of the processes and factors that control SM patterns at non-punctual scales might result from information collected in larger volume of subsoil or larger study area. Indeed, sensing greater volumes of soil over larger areas would filter less important details that derive from a simple sum of multi-point measurements and would be useful to emphasize the characteristics emerging at larger scales. This implies the collection of measurements on a large number of points distributed over larger scales, although characterized by lower accuracy. Recently, geophysical methods have received special attention thanks to their ability to collect information that go beyond the local information sensed with traditional sensors. Between potentially useful methods, the Electro-Magnetic Induction (EMI) method has been indicated as one of the most promising for hydrological applications. Ground-based EMI sensors are lightweight, do not require contact with the soil allowing a considerable reduction of the survey costs as long as the spatial extent of the area of interest grows. Moreover, the ability to measure through thicknesses of soil greater than some centimetres and the possibility to collect data in wooded areas make the use of these sensors

  13. Repeated electromagnetic induction measurements for mapping soil moisture at the field scale: comparison with data from a wireless soil moisture monitoring network

    NASA Astrophysics Data System (ADS)

    Martini, Edoardo; Werban, Ulrike; Zacharias, Steffen; Pohle, Marco; Dietrich, Peter; Wollschläger, Ute

    2016-04-01

    Electromagnetic induction (EMI) methods are widely used for soil mapping, as they allow fast and relatively low-cost surveys of soil apparent electrical conductivity (ECa) at various scales. Soil ECa is well known to be influenced by both the volumetric content and the electrical conductivity (EC) of soil water, as well as by soil temperature and by the volume of the solid particles and their EC. Among other applications, EMI has become widely used to determine soil water content or to study hydrological processes within the field of hydrogeophysics. Although the use of non-invasive EMI for imaging soil spatial properties is very attractive, the dependence of ECa on several properties and states challenges any interpretation with respect to individual soil properties or states such as θ. The major aim of this study was to further investigate the potential of repeated EMI measurements to map soil moisture at the hillslope scale, with particular focus on the temporal variability of the spatial patterns of ECa and soil moisture, respectively, and on the stability of the ECa-soil moisture relationship over time. To this end, we compared time series of EMI measurements with high-resolution soil moisture data for a non-intensively managed hillslope area in the Schäfertal catchment (Central Germany) for which the spatial distribution of soil properties and soil water dynamics were known in detail. Soil water and temperature dynamics were observed in 40 soil profiles at hourly resolution during 14 months using a wireless monitoring network. During this period of time, ECa was mapped on seven occasions using an EM38-DD device. For the investigated site, ECa showed small temporal variations (ranging between 0 and 24 mS/m) whereas the temporal range of soil moisture was very large (from very dry to soil saturation). Furthermore, temporal changes of the spatial pattern of ECa differed from temporal changes of the spatial pattern of soil moisture. The ECa-soil moisture

  14. Module Eight: Induction; Basic Electricity and Electronics Individualized Learning System.

    ERIC Educational Resources Information Center

    Bureau of Naval Personnel, Washington, DC.

    The module covers in greater depth electromagnetic induction, its effects, and how it is used to advantage in electrical circuits; and the physical components, called inductors, designed to take advantage of the phenomenon of electromagnetic induction. This module is divided into four lessons: electromagnetism; inductors and flux density, inducing…

  15. Electromagnetic Processing of Materials:. from the Concepts to Industrial Applications

    NASA Astrophysics Data System (ADS)

    Delannoy, Y.

    2005-07-01

    Electromagnetic fields are used for material processing in various industrial devices, such as induction furnaces, electromagnetic brakes and stirrers in metallurgy, inductive plasma torches to elaborate silica for optical fibres or electromagnetic flow control systems in crystal growth. New developments are needed whenever the coupling of physical phenomena is the key point of the process. Three examples are presented among the research activities of the EPM laboratory in Electromagnetic Processing of Materials: Electromagnetic continuous casting of steel slabs, plasma purification of silicon, electromagnetic stirring of solidifying alloys. Some scientific open questions important for such processes are presented.

  16. Electromagnetic particle simulation codes

    NASA Technical Reports Server (NTRS)

    Pritchett, P. L.

    1985-01-01

    Electromagnetic particle simulations solve the full set of Maxwell's equations. They thus include the effects of self-consistent electric and magnetic fields, magnetic induction, and electromagnetic radiation. The algorithms for an electromagnetic code which works directly with the electric and magnetic fields are described. The fields and current are separated into transverse and longitudinal components. The transverse E and B fields are integrated in time using a leapfrog scheme applied to the Fourier components. The particle pushing is performed via the relativistic Lorentz force equation for the particle momentum. As an example, simulation results are presented for the electron cyclotron maser instability which illustrate the importance of relativistic effects on the wave-particle resonance condition and on wave dispersion.

  17. Source localization of intermittent rhythmic delta activity in a patient with acute confusional migraine: cross-spectral analysis using standardized low-resolution brain electromagnetic tomography (sLORETA).

    PubMed

    Kim, Dae-Eun; Shin, Jung-Hyun; Kim, Young-Hoon; Eom, Tae-Hoon; Kim, Sung-Hun; Kim, Jung-Min

    2016-01-01

    Acute confusional migraine (ACM) shows typical electroencephalography (EEG) patterns of diffuse delta slowing and frontal intermittent rhythmic delta activity (FIRDA). The pathophysiology of ACM is still unclear but these patterns suggest neuronal dysfunction in specific brain areas. We performed source localization analysis of IRDA (in the frequency band of 1-3.5 Hz) to better understand the ACM mechanism. Typical IRDA EEG patterns were recorded in a patient with ACM during the acute stage. A second EEG was obtained after recovery from ACM. To identify source localization of IRDA, statistical non-parametric mapping using standardized low-resolution brain electromagnetic tomography was performed for the delta frequency band comparisons between ACM attack and non-attack periods. A difference in the current density maximum was found in the dorsal anterior cingulated cortex (ACC). The significant differences were widely distributed over the frontal, parietal, temporal and limbic lobe, paracentral lobule and insula and were predominant in the left hemisphere. Dorsal ACC dysfunction was demonstrated for the first time in a patient with ACM in this source localization analysis of IRDA. The ACC plays an important role in the frontal attentional control system and acute confusion. This dysfunction of the dorsal ACC might represent an important ACM pathophysiology.

  18. Phasic brain activity related to the onset of rapid eye movements during rapid eye movement sleep: study of event-related potentials and standardized low-resolution brain electromagnetic tomography.

    PubMed

    Ogawa, Keiko; Abe, Takashi; Nittono, Hiroshi; Yamazaki, Katuo; Hori, Tadao

    2010-09-01

    The function of rapid eye movements (REMs) during REM sleep is still a matter that is open to debate. In a previous study, we found positive brain potential (P200r) time-locked to the onset of REMs. This potential was not observed during saccades of wakefulness. In this study, we estimated the electrical generation of this potential to investigate the phasic brain activity related to REMs. Data were collected in a sleep laboratory from nine healthy university students. REMs during REM sleep were recorded during natural nocturnal sleep. Event-related potential time-locked to the onset of REMs were averaged. Standardized low-resolution brain electromagnetic tomography (sLORETA) was used to identify the current sources of P200r. The results showed that P200r have neuronal generators in the left premotor area, left primary motor and sensory cortices, left inferior parietal lobule and bilateral occipital areas (precuneus, cuneus and lingual gyrus). All these areas are known to contribute to visuomotor processing. These phasic brain activities might play a key role in explaining the function of REMs during REM sleep.

  19. Investigation of Non-Linear Dynamics of the Rock Massive,Using Seismological Catalogue data and Induction Electromagnetic Monitoring Data in a Rock Burst Mine.

    NASA Astrophysics Data System (ADS)

    Hachay, O. A.; Khachay, O. Y.; Klimko, V. K.; Shipeev, O. V.

    2012-04-01

    Geological medium is an open dynamical system, which is influenced on different scales by natural and man-made impacts, which change the medium state and lead as a result to a complicated many ranked hierarchic evolution. That is the subject of geo synergetics. Paradigm of physical mesomechanics, which was advanced by academician Panin V.E. and his scientific school, which includes the synergetic approach is a constructive method for research and changing the state of heterogenic materials [1]. That result had been obtained on specimens of different materials. In our results of research of no stationary geological medium in a frame of natural experiments in real rock massifs, which are under high man-made influence it was shown, that the state dynamics can be revealed with use synergetics in hierarchic medium. Active and passive geophysical monitoring plays a very important role for research of the state of dynamical geological systems. It can be achieved by use electromagnetic and seismic fields. Our experience of that research showed the changing of the system state reveals on the space scales and times in the parameters, which are linked with the peculiarities of the medium of the second or higher ranks [2-5]. Results of seismological and electromagnetic information showed the mutual additional information on different space-time levels of rock massive state, which are energetic influenced by explosions, used in mining technology. It is revealed a change of nonlinearity degree in time of the massive state by active influence on it. The description of massive movement in a frame of linear dynamical system does not satisfy the practical situation. The received results are of great significance because for the first time we could find the coincidences with the mathematical theory of open systems and experimental natural results with very complicated structure. On that base we developed a new processing method for the seismological information which can be used in

  20. Advanced high-temperature electromagnetic pump

    NASA Technical Reports Server (NTRS)

    Gahan, J. W.; Powell, A. H.

    1972-01-01

    Three phase helical, electromagnetic induction pump for use as boiler feed pump in potassium Rankine-cycle power system is described. Techniques for fabricating components of pump are discussed. Specifications of pump are analyzed.

  1. Cell Type-Dependent Induction of DNA Damage by 1800 MHz Radiofrequency Electromagnetic Fields Does Not Result in Significant Cellular Dysfunctions

    PubMed Central

    Xu, Shanshan; Chen, Guangdi; Chen, Chunjing; Sun, Chuan; Zhang, Danying; Murbach, Manuel; Kuster, Niels; Zeng, Qunli; Xu, Zhengping

    2013-01-01

    Background Although IARC clarifies radiofrequency electromagnetic fields (RF-EMF) as possible human carcinogen, the debate on its health impact continues due to the inconsistent results. Genotoxic effect has been considered as a golden standard to determine if an environmental factor is a carcinogen, but the currently available data for RF-EMF remain controversial. As an environmental stimulus, the effect of RF-EMF on cellular DNA may be subtle. Therefore, more sensitive method and systematic research strategy are warranted to evaluate its genotoxicity. Objectives To determine whether RF-EMF does induce DNA damage and if the effect is cell-type dependent by adopting a more sensitive method γH2AX foci formation; and to investigate the biological consequences if RF-EMF does increase γH2AX foci formation. Methods Six different types of cells were intermittently exposed to GSM 1800 MHz RF-EMF at a specific absorption rate of 3.0 W/kg for 1 h or 24 h, then subjected to immunostaining with anti-γH2AX antibody. The biological consequences in γH2AX-elevated cell type were further explored with comet and TUNEL assays, flow cytometry, and cell growth assay. Results Exposure to RF-EMF for 24 h significantly induced γH2AX foci formation in Chinese hamster lung cells and Human skin fibroblasts (HSFs), but not the other cells. However, RF-EMF-elevated γH2AX foci formation in HSF cells did not result in detectable DNA fragmentation, sustainable cell cycle arrest, cell proliferation or viability change. RF-EMF exposure slightly but not significantly increased the cellular ROS level. Conclusions RF-EMF induces DNA damage in a cell type-dependent manner, but the elevated γH2AX foci formation in HSF cells does not result in significant cellular dysfunctions. PMID:23355902

  2. ELECTROMAGNETIC PUMP

    DOEpatents

    Pulley, O.O.

    1954-08-17

    This patent reiates to electromagnetic pumps for electricity-conducting fluids and, in particular, describes several modifications for a linear conduction type electromagnetic interaction pump. The invention resides in passing the return conductor for the current traversing the fiuid in the duct back through the gap in the iron circuit of the pump. Both the maximum allowable pressure and the efficiency of a linear conduction electromagnetic pump are increased by incorporation of the present invention.

  3. Electromagnetic Attraction.

    ERIC Educational Resources Information Center

    Milson, James L.

    1990-01-01

    Three activities involving electromagnetism are presented. Discussed are investigations involving the construction of an electromagnet, the effect of the number of turns of wire in the magnet, and the effect of the number of batteries in the circuit. Extension activities are suggested. (CW)

  4. Electromagnetic fasteners

    DOEpatents

    Crane, Randolph W.; Marts, Donna J.

    1994-01-01

    An electromagnetic fastener for manipulating objects in space uses the matic attraction of various metals. An end effector is attached to a robotic manipulating system having an electromagnet such that when current is supplied to the electromagnet, the object is drawn and affixed to the end effector, and when the current is withheld, the object is released. The object to be manipulated includes a multiplicity of ferromagnetic patches at various locations to provide multiple areas for the effector on the manipulator to become affixed to the object. The ferromagnetic patches are sized relative to the object's geometry and mass.

  5. Electromagnetic fasteners

    DOEpatents

    Crane, Randolph W.; Marts, Donna J.

    1994-11-01

    An electromagnetic fastener for manipulating objects in space uses the matic attraction of various metals. An end effector is attached to a robotic manipulating system having an electromagnet such that when current is supplied to the electromagnet, the object is drawn and affixed to the end effector, and when the current is withheld, the object is released. The object to be manipulated includes a multiplicity of ferromagnetic patches at various locations to provide multiple areas for the effector on the manipulator to become affixed to the object. The ferromagnetic patches are sized relative to the object's geometry and mass.

  6. Earth's Electromagnetic Environment

    NASA Astrophysics Data System (ADS)

    Constable, Catherine

    2016-01-01

    The natural spectrum of electromagnetic variations surrounding Earth extends across an enormous frequency range and is controlled by diverse physical processes. Electromagnetic (EM) induction studies make use of external field variations with frequencies ranging from the solar cycle which has been used for geomagnetic depth sounding through the 10^{-4}-10^4 Hz frequency band widely used for magnetotelluric and audio-magnetotelluric studies. Above 10^4 Hz, the EM spectrum is dominated by man-made signals. This review emphasizes electromagnetic sources at ˜1 Hz and higher, describing major differences in physical origin and structure of short- and long-period signals. The essential role of Earth's internal magnetic field in defining the magnetosphere through its interactions with the solar wind and interplanetary magnetic field is briefly outlined. At its lower boundary, the magnetosphere is engaged in two-way interactions with the underlying ionosphere and neutral atmosphere. Extremely low-frequency (3 Hz-3 kHz) electromagnetic signals are generated in the form of sferics, lightning, and whistlers which can extend to frequencies as high as the VLF range (3-30 kHz).The roughly spherical dielectric cavity bounded by the ground and the ionosphere produces the Schumann resonance at around 8 Hz and its harmonics. A transverse resonance also occurs at 1.7-2.0 kHz arising from reflection off the variable height lower boundary of the ionosphere and exhibiting line splitting due to three-dimensional structure. Ground and satellite observations are discussed in the light of their contributions to understanding the global electric circuit and for EM induction studies.

  7. Inductive shearing of drilling pipe

    SciTech Connect

    Ludtka, Gerard M.; Wilgen, John; Kisner, Roger; Mcintyre, Timothy

    2016-04-19

    Induction shearing may be used to cut a drillpipe at an undersea well. Electromagnetic rings may be built into a blow-out preventer (BOP) at the seafloor. The electromagnetic rings create a magnetic field through the drillpipe and may transfer sufficient energy to change the state of the metal drillpipe to shear the drillpipe. After shearing the drillpipe, the drillpipe may be sealed to prevent further leakage of well contents.

  8. Inductive dielectric analyzer

    NASA Astrophysics Data System (ADS)

    Agranovich, Daniel; Polygalov, Eugene; Popov, Ivan; Ben Ishai, Paul; Feldman, Yuri

    2017-03-01

    One of the approaches to bypass the problem of electrode polarization in dielectric measurements is the free electrode method. The advantage of this technique is that, the probing electric field in the material is not supplied by contact electrodes, but rather by electromagnetic induction. We have designed an inductive dielectric analyzer based on a sensor comprising two concentric toroidal coils. In this work, we present an analytic derivation of the relationship between the impedance measured by the sensor and the complex dielectric permittivity of the sample. The obtained relationship was successfully employed to measure the dielectric permittivity and conductivity of various alcohols and aqueous salt solutions.

  9. Vector Potential, Electromagnetic Induction and "Physical Meaning"

    ERIC Educational Resources Information Center

    Giuliani, G.

    2010-01-01

    A forgotten experiment by Andre Blondel (1914) proves, as held on the basis of theoretical arguments in a previous paper, that the time variation of the magnetic flux is not the cause of the induced emf; the physical agent is instead the vector potential through the term [equation omitted] (when the induced circuit is at rest). The "good…

  10. Mapping Pesticide Partition Coefficients By Electromagnetic Induction

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A potential method for reducing pesticide leaching is to base application rates on the leaching potential of a specific chemical and soil combination. However, leaching is determined in part by the partitioning of the chemical between the soil and soil solution, which varies across a field. Standard...

  11. Electromagnetic Induction: A Computer-Assisted Experiment

    ERIC Educational Resources Information Center

    Fredrickson, J. E.; Moreland, L.

    1972-01-01

    By using minimal equipment it is possible to demonstrate Faraday's Law. An electronic desk calculator enables sophomore students to solve a difficult mathematical expression for the induced EMF. Polaroid pictures of the plot of induced EMF, together with the computer facility, enables students to make comparisons. (PS)

  12. Portable Electromagnetic Induction Sensor with Integrated Positioning

    DTIC Science & Technology

    2013-08-20

    500 kS/s, Simultaneous AI C Series Module for B. Barrowes, D. George, F. Shubitidze -20- MR-1712 - Pedemis Final Report 4 MATERIALS AND METHODS...quantity measured by an EMI receiver is the electromotive force given by the negative time derivative of the flux through its area: E =−dΦ dt =− d dt ∫ B...of Elkton Series type soil[53]. The Elkton Series consist of very deep, slowly permeable, poorly drained soils. These soils formed in silty aeolian

  13. Nuclear Electromagnetic Pulse Review

    NASA Astrophysics Data System (ADS)

    Dinallo, Michael

    2011-04-01

    Electromagnetic Pulse (EMP) from nuclear detonations have been observed for well over half a century. Beginning in the mid-to-late 1950s, the physics and modeling of EMP has been researched and will continue into the foreseeable future. The EMP environment propagates hundreds of miles from its origins and causes interference for all types of electronic instrumentation. This includes military, municipal and industry based electronic infrastructures such as power generation and distribution, command and control systems, systems used in financial and emergency services, electronic monitoring and communications networks, to mention some key infrastructure elements. Research into EMP has included originating physics, propagation and electromagnetic field coupling analyses and measurement-sensor development. Several methods for calculating EMP induced transient interference (voltage and current induction) will be briefly discussed and protection techniques reviewed. These methods can be mathematically simple or involve challenging boundary value solution techniques. A few illustrative calculations will demonstrate the concern for electronic system operability. Analyses such as the Wunsch-Bell model for electronic upset or damage, and the Singularity Expansion Method (SEM) put forth by Dr. Carl Baum, will facilitate the concern for EMP effects. The SEM determines the voltages and currents induced from transient electromagnetic fields in terms of natural modes of various types of electronic platforms (aerospace vehicles or land-based assets - fixed or mobile). Full-scale facility and laboratory simulation and response measurement approaches will be discussed. The talk will conclude with a discussion of some present research activities.

  14. 2-D and 3-D Visualization of the Freshwater/Saltwater Mixing Front, and Zones of Preferential Groundwater Flow in the Karst Biscayne Coastal Aquifer using Electromagnetic Induction Techniques, Miami, Southeastern Florida.

    NASA Astrophysics Data System (ADS)

    Stalker, J. C.; Glaccum, R.

    2005-05-01

    The Biscayne aquifer is unconfined, composed primarily of Karst limestone, and underlies all of Miami-Dade County and much of Biscayne Bay in southeastern Florida. It is the sole source of drinking water for the 3 million inhabitants of the city of Miami and Miami-Dade County, as well as portions of Broward and Monroe Counties. Saltwater intrusion is a prominent problem for all coastal aquifers including the Biscayne aquifer. Simple and quick detection of the three-dimensional saltwater/freshwater interface has been problematic without the use of extensive sounding surveys or multiple well sampling. We are developing a technique combining rapid EM-31 surface surveys with EM-31 vertical soundings to model the depth to the saltwater/freshwater front at two sites located within a half mile of Biscayne Bay. The EM-31 has a maximum signal penetration of about 25ft allowing for accurate near shore surveys. Depths to the saltwater have ranged from over 25 ft inland to less than 2-3 ft near the Bay and saltwater mangroves. Changes in conductivity along survey lines of equal elevation that are equidistant from the Bay may indicate zones of preferential flow due to conduit networks or the presence of backfill, both of which exacerbate saltwater intrusion. All surveys show a rapid change from fresh to brackish water as you move toward the Bay indicating a shallow and abrupt mixing zone. Using a simple depth-modeling program, a wire frame contour map of the mixing zone can be constructed. This technique has proven to be a quick, inexpensive method for first-order hydrogeological and spatial analysis of the saltwater/freshwater interface. In an allied study we are using down-hole electromagnetic induction techniques with an EM-39 tool on existing wells, analyzing fluctuations in conductivity within the saltwater zone to look for zones of high permeability in the aquifer. Conductivity fluctuates within the mixing zone from brackish values to values equivalent to Biscayne Bay

  15. Inductance Calculations of Variable Pitch Helical Inductors

    DTIC Science & Technology

    2015-08-01

    Electromagnetic Phenomena. July 2003;3:392–396. 2. Snow C. Formulas for computing capacitance and inductance . In: National bu- reau of standards circular 544...ARL-TR-7380 ● AUG 2015 US Army Research Laboratory Inductance Calculations of Variable Pitch Helical Inductors by Peter T...report when it is no longer needed. Do not return it to the originator. ARL-TR-7380 ● AUG 2015 US Army Research Laboratory Inductance

  16. Electromagnetically driven liquid iris

    NASA Astrophysics Data System (ADS)

    Jang, Deasung; Jeong, Jin Won; Lee, Dae Young; Kim, Dae Geun; Chung, Sang Kug

    2016-11-01

    This paper describes a tunable liquid iris driven by electromagnetic actuation for miniature cameras. To examine the magnetic effect on a ferrofluid, the contact angle modification of a sessile ferrofluid droplet is tested using a neodymium magnet and an electric coil which 2.5 A current is applied to. The contact angle variations of the ferrofluid droplet for each test are 21.3 and 18.1 degrees, respectively. As a proof of concept, a pretest of a tunable iris actuated by electromagnetic effect is performed by using a hollow cylinder cell. As applying the current, the aperture diameter is adjusted from 4.06 mm at 0A to 3.21 mm at 2.0A. Finally, a tunable liquid iris (9 x 9 x 2 mm3) , consisting of two connected circular microchannels, is realized using MEMS technology. the aperture diameter of the tunable liquid iris is able to be modified from 1.72 mm at 0 A to 1.15 mm at 2.6 A. This tunable optical iris has potential applications not only for portable electronic devices but also in biomedical fields such as optical coherence tomography and microsurgery. This work was supported by 2016 Research Fund of Myongji University.

  17. Status of FED/INTOR electromagnetics

    SciTech Connect

    Murray, J.G.

    1983-02-01

    This report provides a summary of the electromagnetic studies, calculations, and conclusions in the evolution of the base design of FED/INTOR (Fusion Engineering Device/International Tokamak Reactor). The electromagnetic feastures include the startup, control, disruptions, and design of structures. This report provides information concerning the evolution of the electromagnetic studies on FED and the justification for the eddy current design feature. The report shows that a major design feature required is the provision of a low induction and resistive path for toroidal currents to flow in the structures in order to provide self-stabilization and to manage the disruption energy dissipation.

  18. Electromagnetic Reciprocity.

    SciTech Connect

    Aldridge, David F.

    2014-11-01

    A reciprocity theorem is an explicit mathematical relationship between two different wavefields that can exist within the same space - time configuration. Reciprocity theorems provi de the theoretical underpinning for mod ern full waveform inversion solutions, and also suggest practical strategies for speed ing up large - scale numerical modeling of geophysical datasets . In the present work, several previously - developed electromagnetic r eciprocity theorems are generalized to accommodate a broader range of medi um, source , and receiver types. Reciprocity relations enabling the interchange of various types of point sources and point receivers within a three - dimensional electromagnetic model are derived. Two numerical modeling algorithms in current use are successfully tested for adherence to reciprocity. Finally, the reciprocity theorem forms the point of departure for a lengthy derivation of electromagnetic Frechet derivatives. These mathe matical objects quantify the sensitivity of geophysical electromagnetic data to variatio ns in medium parameters, and thus constitute indispensable tools for solution of the full waveform inverse problem. ACKNOWLEDGEMENTS Sandia National Labor atories is a multi - program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the US Department of Energy's National Nuclear Security Administration under contract DE - AC04 - 94AL85000. Signif icant portions of the work reported herein were conducted under a Cooperative Research and Development Agreement (CRADA) between Sandia National Laboratories (SNL) and CARBO Ceramics Incorporated. The author acknowledges Mr. Chad Cannan and Mr. Terry Pa lisch of CARBO Ceramics, and Ms. Amy Halloran, manager of SNL's Geophysics and Atmospheric Sciences Department, for their interest in and encouragement of this work. Special thanks are due to Dr . Lewis C. Bartel ( recently retired from Sandia National Labo ratories and now a

  19. RESEARCH PAPERS : Geomagnetic induction in multiple eccentrically nested spheres

    NASA Astrophysics Data System (ADS)

    Martinec, Z.

    1998-01-01

    We present a semi-analytic solution to the 3-D forward modelling of electromagnetic induction in a heterogeneous model consisting of multiple eccentrically nested spheres. A number of numerical methods for 2-D and 3-D global electromagnetic modelling have been applied recently, including thin-sheet, perturbation-expansion, finite-element and spectral-finite-element schemes. The present semi-analytical approach may be used as an aid for testing more general algorithms of electromagnetic induction modelling. The multiple eccentrically nested spheres solution has been tested by comparing against the analytical solution for electromagnetic induction in a uniform sphere and in two eccentrically nested spheres with an azimuthal structure of electrical conductivity, and good agreements have been obtained. We further solve the electromagnetic induction problem in three and four eccentrically nested spheres configurations and compute the global response function and the spherical components of magnetic intensity within the model.

  20. Electromagnetic propulsion for spacecraft

    NASA Technical Reports Server (NTRS)

    Myers, Roger M.

    1993-01-01

    Three electromagnetic propulsion technologies, solid propellant pulsed plasma thrusters (PPT), magnetoplasmadynamic (MPD) thrusters, and pulsed inductive thrusters (PIT) have been developed for application to auxiliary and primary spacecraft propulsion. Both the PPT and MPD thrusters have been flown in space, though only PPTs have been used on operational satellites. The performance of operational PPTs is quite poor, providing only about 8 percent efficiency at about 1000 sec specific impulse. Laboratory PPTs yielding 34 percent efficiency at 5170 sec specific impulse have been demonstrated. Laboratory MPD thrusters have been demonstrated with up to 70 percent efficiency and 7000 sec specific impulse. Recent PIT performance measurements using ammonia and hydrazine propellants are extremely encouraging, reaching 50 percent efficiency for specific impulses between 4000 and 8000 sec.

  1. Electromagnetic propulsion for spacecraft

    NASA Technical Reports Server (NTRS)

    Myers, Roger M.

    1993-01-01

    Three electromagnetic propulsion technologies, solid propellant pulsed plasma thrusters (PPT), magnetoplasmadynamic (MPD) thrusters, and pulsed inductive thrusters (PIT), were developed for application to auxiliary and primary spacecraft propulsion. Both the PPT and MPD thrusters were flown in space, though only PPT's were used on operational satellites. The performance of operational PPT's is quite poor, providing only approximately 8 percent efficiency at approximately 1000 s specific impulse. However, laboratory PPT's yielding 34 percent efficiency at 2000 s specific impulse were extensively tested, and peak performance levels of 53 percent efficiency at 5170 s specific impulse were demonstrated. MPD thrusters were flown as experiments on the Japanese MS-T4 spacecraft and the Space Shuttle and were qualified for a flight in 1994. The flight MPD thrusters were pulsed, with a peak performance of 22 percent efficiency at 2500 s specific impulse using ammonia propellant. Laboratory MPD thrusters were demonstrated with up to 70 percent efficiency and 700 s specific impulse using lithium propellant. While the PIT thruster has never been flown, recent performance measurements using ammonia and hydrazine propellants are extremely encouraging, reaching 50 percent efficiency for specific impulses between 4000 to 8000 s. The fundamental operating principles, performance measurements, and system level design for the three types of electromagnetic thrusters are reviewed, and available data on flight tests are discussed for the PPT and MPD thrusters.

  2. Induction plasma tube

    DOEpatents

    Hull, D.E.

    1982-07-02

    An induction plasma tube having a segmented, fluid-cooled internal radiation shield is disclosed. The individual segments are thick in cross-section such that the shield occupies a substantial fraction of the internal volume of the plasma enclosure, resulting in improved performance and higher sustainable plasma temperatures. The individual segments of the shield are preferably cooled by means of a counterflow fluid cooling system wherein each segment includes a central bore and a fluid supply tube extending into the bore. The counterflow cooling system results in improved cooling of the individual segments and also permits use of relatively larger shield segments which permit improved electromagnetic coupling between the induction coil and a plasma located inside the shield. Four embodiments of the invention, each having particular advantages, are disclosed.

  3. Induction plasma tube

    DOEpatents

    Hull, Donald E.

    1984-01-01

    An induction plasma tube having a segmented, fluid-cooled internal radiation shield is disclosed. The individual segments are thick in cross-section such that the shield occupies a substantial fraction of the internal volume of the plasma enclosure, resulting in improved performance and higher sustainable plasma temperatures. The individual segments of the shield are preferably cooled by means of a counterflow fluid cooling system wherein each segment includes a central bore and a fluid supply tube extending into the bore. The counterflow cooling system results in improved cooling of the individual segments and also permits use of relatively larger shield segments which permit improved electromagnetic coupling between the induction coil and a plasma located inside the shield. Four embodiments of the invention, each having particular advantages, are disclosed.

  4. Electromagnetic microactuators

    NASA Astrophysics Data System (ADS)

    Büttgenbach, S.; Al-Halhouli, A. T.; Feldmann, M.; Seidemann, V.; Waldschik, A.

    2013-05-01

    High precision microactuators have become key elements for many applications of MEMS, for example for positioning and handling systems as well as for microfluidic devices. Electromagnetic microactuators exhibit considerable benefits such as high forces, large deflections, low input impedances and thus, the involvement of only low voltages. Most of the magnetic microactuators developed so far are based on the variable reluctance principle and use soft magnetic materials. Since the driving force of such actuators is proportional to their volume, they require structures with rather great heights and aspect ratios. Therefore, the development of new photo resists, which allow UV exposure of thick layers of resist, has been essential for the advancement of variable reluctance microactuators. On the other hand, hard magnetic materials have the potential for larger forces and larger deflections. Accordingly, polymer magnets, in which micro particles of hard magnetic material are suspended in a polymer matrix, have been used to fabricate permanent magnet microactuators. In this paper we give an overview of sophisticated electromagnetic microactuators which have been developed in our laboratory in the framework of the Collaborative Research Center "Design and Manufacturing of Active Microsystems". In particular, concept, fabrication and test of variable reluctance micro stepper motors, of permanent magnet synchronous micromotors and of microactuators based on the Lorentz force principle will be described. Special emphasis will be given to applications in lab-on-chip systems.

  5. Calculation of electromagnetic force in electromagnetic forming process of metal sheet

    SciTech Connect

    Xu Da; Liu Xuesong; Fang Kun; Fang Hongyuan

    2010-06-15

    Electromagnetic forming (EMF) is a forming process that relies on the inductive electromagnetic force to deform metallic workpiece at high speed. Calculation of the electromagnetic force is essential to understand the EMF process. However, accurate calculation requires complex numerical solution, in which the coupling between the electromagnetic process and the deformation of workpiece needs be considered. In this paper, an appropriate formula has been developed to calculate the electromagnetic force in metal work-piece in the sheet EMF process. The effects of the geometric size of coil, the material properties, and the parameters of discharge circuit on electromagnetic force are taken into consideration. Through the formula, the electromagnetic force at different time and in different positions of the workpiece can be predicted. The calculated electromagnetic force and magnetic field are in good agreement with the numerical and experimental results. The accurate prediction of the electromagnetic force provides an insight into the physical process of the EMF and a powerful tool to design optimum EMF systems.

  6. Electromagnetic pulses bone healing booster

    NASA Astrophysics Data System (ADS)

    Sintea, S. R.; Pomazan, V. M.; Bica, D.; Grebenisan, D.; Bordea, N.

    2015-11-01

    Posttraumatic bone restoration triggered by the need to assist and stimulate compensatory bone growth in periodontal condition. Recent studies state that specific electromagnetic stimulation can boost the bone restoration, reaching up to 30% decrease in recovery time. Based on the existing data on the electromagnetic parameters, a digital electronic device is proposed for intra oral mounting and bone restoration stimulation in periodontal condition. The electrical signal is applied to an inductive mark that will create and impregnate magnetic field in diseased tissue. The device also monitors the status of the electromagnetic field. Controlled wave forms and pulse frequency signal at programmable intervals are obtained with optimized number of components and miniaturized using surface mounting devices (SMD) circuits and surface mounting technology (SMT), with enhanced protection against abnormal current growth, given the intra-oral environment. The system is powered by an autonomous power supply (battery), to limit the problems caused by powering medical equipment from the main power supply. Currently the device is used in clinical testing, in cycles of six up to twelve months. Basic principles for the electrical scheme and algorithms for pulse generation, pulse control, electromagnetic field control and automation of current monitoring are presented, together with the friendly user interface, suitable for medical data and patient monitoring.

  7. Gravitational induction

    NASA Astrophysics Data System (ADS)

    Bini, Donato; Cherubini, Christian; Chicone, Carmen; Mashhoon, Bahram

    2008-11-01

    We study the linear post-Newtonian approximation to general relativity known as gravitoelectromagnetism (GEM); in particular, we examine the similarities and differences between GEM and electrodynamics. Notwithstanding some significant differences between them, we find that a special nonstationary metric in GEM can be employed to show explicitly that it is possible to introduce gravitational induction within GEM in close analogy with Faraday's law of induction and Lenz's law in electrodynamics. Some of the physical implications of gravitational induction are briefly discussed.

  8. Electromagnetic Radiation System (EMRS) for Susceptibility Testing.

    DTIC Science & Technology

    ELECTROMAGNETIC COMPATIBILITY, *ELECTROMAGNETIC SUSCEPTIBILITY, COMMUNICATION EQUIPMENT, ELECTRONIC EQUIPMENT, ELECTROMAGNETIC RADIATION , ANTENNAS, ELECTROMAGNETIC INTERFERENCE, RADAR SIGNALS, RADIO SIGNALS, FIELD INTENSITY.

  9. Computer simulation and optimal designing of energy-saving technologies of the induction heating of metals

    NASA Astrophysics Data System (ADS)

    Demidovich, V. B.

    2012-12-01

    Advanced energy-saving technologies of induction heating of metals are discussed. The importance of the joint simulation of electromagnetic and temperature fields on induction heating is demonstrated. The package of specialized programs for simulating not only induction heating devices, but also technologies that employ industrial heating has been developed. An intimate connection between optimal design and control of induction heaters is shown.

  10. Closed inductively coupled plasma cell

    DOEpatents

    Manning, Thomas J.; Palmer, Byron A.; Hof, Douglas E.

    1990-01-01

    A closed inductively coupled plasma cell generates a relatively high power, low noise plasma for use in spectroscopic studies. A variety of gases can be selected to form the plasma to minimize spectroscopic interference and to provide a electron density and temperature range for the sample to be analyzed. Grounded conductors are placed at the tube ends and axially displaced from the inductive coil, whereby the resulting electromagnetic field acts to elongate the plasma in the tube. Sample materials can be injected in the plasma to be excited for spectroscopy.

  11. Closed inductively coupled plasma cell

    DOEpatents

    Manning, T.J.; Palmer, B.A.; Hof, D.E.

    1990-11-06

    A closed inductively coupled plasma cell generates a relatively high power, low noise plasma for use in spectroscopic studies is disclosed. A variety of gases can be selected to form the plasma to minimize spectroscopic interference and to provide a electron density and temperature range for the sample to be analyzed. Grounded conductors are placed at the tube ends and axially displaced from the inductive coil, whereby the resulting electromagnetic field acts to elongate the plasma in the tube. Sample materials can be injected in the plasma to be excited for spectroscopy. 1 fig.

  12. Inductive reasoning.

    PubMed

    Hayes, Brett K; Heit, Evan; Swendsen, Haruka

    2010-03-01

    Inductive reasoning entails using existing knowledge or observations to make predictions about novel cases. We review recent findings in research on category-based induction as well as theoretical models of these results, including similarity-based models, connectionist networks, an account based on relevance theory, Bayesian models, and other mathematical models. A number of touchstone empirical phenomena that involve taxonomic similarity are described. We also examine phenomena involving more complex background knowledge about premises and conclusions of inductive arguments and the properties referenced. Earlier models are shown to give a good account of similarity-based phenomena but not knowledge-based phenomena. Recent models that aim to account for both similarity-based and knowledge-based phenomena are reviewed and evaluated. Among the most important new directions in induction research are a focus on induction with uncertain premise categories, the modeling of the relationship between inductive and deductive reasoning, and examination of the neural substrates of induction. A common theme in both the well-established and emerging lines of induction research is the need to develop well-articulated and empirically testable formal models of induction. Copyright © 2010 John Wiley & Sons, Ltd. For further resources related to this article, please visit the WIREs website.

  13. Electromagnetic topology: Characterization of internal electromagnetic coupling

    NASA Technical Reports Server (NTRS)

    Parmantier, J. P.; Aparicio, J. P.; Faure, F.

    1991-01-01

    The main principles are presented of a method dealing with the resolution of electromagnetic internal problems: Electromagnetic Topology. A very interesting way is to generalize the multiconductor transmission line network theory to the basic equation of the Electromagnetic Topology: the BLT equation. This generalization is illustrated by the treatment of an aperture as a four port junction. Analytical and experimental derivations of the scattering parameters are presented. These concepts are used to study the electromagnetic coupling in a scale model of an aircraft, and can be seen as a convenient means to test internal electromagnetic interference.

  14. Electromagnetic launcher

    SciTech Connect

    Laskaris, E.T.; Chari, M.V.K.

    1990-11-20

    This paper describes an electromagnetic launcher. It comprises: a stationary superconductive coil situated coaxially in a cylindrical vacuum vessel for providing a magnetic field. The superconductive coil having a central aperture, the vacuum vessel having an axially extending bore passing through the central aperture of the superconducting coil; a resistive coil situated coaxially with the superconductive coil and movable axially relative to the stationary superconductive coil, the outer diameter of the resistive coil being smaller than the inner diameter of the bore permitting the resistive coil to pass therethrough; launch activating means coupled to the resistive coil. The launch activating means comprising a shaft joined at one end to the resistive coil, a tube open at both ends, a sliding piston situated in the tube and connected to the other end of the shaft; and power supply means coupled to the resistive coil for providing current of a desired direction and magnitude, so that energization of the resistive coil in the presence of the radial field component of the magnetic field of the superconductive coil creates an axial force on the movable coil, the direction and magnitude of which is dependent on the direction and magnitude of the current in the resistive coil.

  15. Electromagnetic launchers

    NASA Astrophysics Data System (ADS)

    Kolm, H.; Mongeau, P.; Williams, F.

    1980-09-01

    Recent advances in energy storage, switching and magnet technology make electromagnetic acceleration a viable alternative to chemical propulsion for certain tasks, and a means to perform other tasks not previously feasible. Applications include the acceleration of gram-size particles for hypervelocity research and the initiation of fusion by impact, a replacement for chemically propelled artillery, the transportation of cargo and personnel over inaccessible terrain, and the launching of space vehicles to supply massive space operations, and for the disposal of nuclear waste. The simplest launcher of interest is the railgun, in which a short-circuit slide or an arc is driven along two rails by direct current. The most sophisticated studied thus far is the mass driver, in which a superconducting shuttle bucket is accelerated by a line of pulse coils energized by capacitors at energy conversion efficiencies better than 90%. Other accelerators of interest include helical, brush-commutated motors, discrete coil arc commutated drivers, flux compression momentum transformers, and various hybrid electrochemical devices.

  16. Pseudolocal tomography

    DOEpatents

    Katsevich, Alexander J.; Ramm, Alexander G.

    1996-01-01

    Local tomographic data is used to determine the location and value of a discontinuity between a first internal density of an object and a second density of a region within the object. A beam of radiation is directed in a predetermined pattern through the region of the object containing the discontinuity. Relative attenuation data of the beam is determined within the predetermined pattern having a first data component that includes attenuation data through the region. The relative attenuation data is input to a pseudo-local tomography function, where the difference between the internal density and the pseudo-local tomography function is computed across the discontinuity. The pseudo-local tomography function outputs the location of the discontinuity and the difference in density between the first density and the second density.

  17. Induction voidmeter

    DOEpatents

    Anderson, Thomas T.; Roop, Conard J.; Schmidt, Kenneth J.; Brewer, John

    1986-01-01

    An induction voidmeter for detecting voids in a conductive fluid may comprise: a four arm bridge circuit having two adjustable circuit elements connected as opposite arms of said bridge circuit, an input branch, and an output branch; two induction coils, bifilarly wound together, connected as the remaining two opposing arms of said bridge circuit and positioned such that the conductive fluid passes through said coils; applying an AC excitation signal to said input branch; and detecting the output signal generated in response to said excitation signal across said output branch. The induction coils may be located outside or inside a non-magnetic pipe containing the conductive fluid.

  18. Induction voidmeter

    DOEpatents

    Anderson, T.T.; Roop, C.J.; Schmidt, K.J.; Brewer, J.

    1983-12-21

    An induction voidmeter for detecting voids in a conductive fluid may comprise: a four arm bridge circuit having two adjustable circuit elements connected as opposite arms of said bridge, an input branch, and an output branch; two induction coils, bifilarly wound together, connected as the remaining two opposing arms of said bridge circuit and positioned such that the conductive fluid passes through said coils; means for applying an AC excitation signal to said input branch; and means for detecting the output signal generated in response to said excitation signal across said output branch. The induction coils may be located outside or inside a non-magnetic pipe containing the conductive fluid.

  19. Megawatt Electromagnetic Plasma Propulsion

    NASA Technical Reports Server (NTRS)

    Gilland, James; Lapointe, Michael; Mikellides, Pavlos

    2003-01-01

    The NASA Glenn Research Center program in megawatt level electric propulsion is centered on electromagnetic acceleration of quasi-neutral plasmas. Specific concepts currently being examined are the Magnetoplasmadynamic (MPD) thruster and the Pulsed Inductive Thruster (PIT). In the case of the MPD thruster, a multifaceted approach of experiments, computational modeling, and systems-level models of self field MPD thrusters is underway. The MPD thruster experimental research consists of a 1-10 MWe, 2 ms pulse-forming-network, a vacuum chamber with two 32 diffusion pumps, and voltage, current, mass flow rate, and thrust stand diagnostics. Current focus is on obtaining repeatable thrust measurements of a Princeton Benchmark type self field thruster operating at 0.5-1 gls of argon. Operation with hydrogen is the ultimate goal to realize the increased efficiency anticipated using the lighter gas. Computational modeling is done using the MACH2 MHD code, which can include real gas effects for propellants of interest to MPD operation. The MACH2 code has been benchmarked against other MPD thruster data, and has been used to create a point design for a 3000 second specific impulse (Isp) MPD thruster. This design is awaiting testing in the experimental facility. For the PIT, a computational investigation using MACH2 has been initiated, with experiments awaiting further funding. Although the calculated results have been found to be sensitive to the initial ionization assumptions, recent results have agreed well with experimental data. Finally, a systems level self-field MPD thruster model has been developed that allows for a mission planner or system designer to input Isp and power level into the model equations and obtain values for efficiency, mass flow rate, and input current and voltage. This model emphasizes algebraic simplicity to allow its incorporation into larger trajectory or system optimization codes. The systems level approach will be extended to the pulsed inductive

  20. Seismic Tomography.

    ERIC Educational Resources Information Center

    Anderson, Don L.; Dziewonski, Adam M.

    1984-01-01

    Describes how seismic tomography is used to analyze the waves produced by earthquakes. The information obtained from the procedure can then be used to map the earth's mantle in three dimensions. The resulting maps are then studied to determine such information as the convective flow that propels the crustal plates. (JN)

  1. The impact of electromagnetic field at a frequency of 50 Hz and a magnetic induction of 2.5 mT on viability of pineal cells in vitro.

    PubMed

    Koziorowska, A; Pasiud, E; Fila, M; Romerowicz-Misielak, M

    2016-01-01

    The impact of electromagnetic fields (EMF) on the pineal gland has been described in numerous studies, but many questions still remain unanswered. The aim of the experiment described in this study was to evaluate the effect of EMF on the viability of the pineal gland cells of pig in vitro. Primary culture of the pineal gland cells has been exposed to the influence of an EMF at a frequency of 50 Hz with 1, 2 or 3 hours and for 3 hours every 2 or 3 days. After the experiment, viability of cells was assessed by MTT assay and compared to a control culture not exposed to electromagnetic fields. We noticed that in respect to the control, exposure of the cells to the EMF induced a significant increase in viability of cells at 2 and 3 hours of exposure. After three days of 3-hour exposure to EMF, we observed a significant decrease in cell viability in relation to the control. The results of these studies suggest that EMF can have a significant biological effect on the cells of the pineal gland in a time-dependent exposure to its action.

  2. Borehole induction coil transmitter

    DOEpatents

    Holladay, Gale; Wilt, Michael J.

    2002-01-01

    A borehole induction coil transmitter which is a part of a cross-borehole electromagnetic field system that is used for underground imaging applications. The transmitter consists of four major parts: 1) a wound ferrite or mu-metal core, 2) an array of tuning capacitors, 3) a current driver circuit board, and 4) a flux monitor. The core is wound with several hundred turns of wire and connected in series with the capacitor array, to produce a tuned coil. This tuned coil uses internal circuitry to generate sinusoidal signals that are transmitted through the earth to a receiver coil in another borehole. The transmitter can operate at frequencies from 1-200 kHz and supplies sufficient power to permit the field system to operate in boreholes separated by up to 400 meters.

  3. COHERENCE PROPERTIES OF ELECTROMAGNETIC RADIATION,

    DTIC Science & Technology

    ELECTROMAGNETIC RADIATION , COHERENT SCATTERING), (*COHERENT SCATTERING, ELECTROMAGNETIC RADIATION ), LIGHT, INTERFERENCE, INTENSITY, STATISTICAL FUNCTIONS, QUANTUM THEORY, BOSONS, INTERFEROMETERS, CHINA

  4. Electromagnetic Education in India

    ERIC Educational Resources Information Center

    Bajpai, Shrish; Asif, Siddiqui Sajida; Akhtar, Syed Adnan

    2016-01-01

    Out of the four fundamental interactions in nature, electromagnetics is one of them along with gravitation, strong interaction and weak interaction. The field of electromagnetics has made much of the modern age possible. Electromagnets are common in day-to-day appliances and are becoming more conventional as the need for technology increases.…

  5. Fundamentals of Electromagnetic Phenomena

    NASA Astrophysics Data System (ADS)

    Lorrain, Paul; Corson, Dale R.; Lorrain, Francois

    Based on the classic Electromagnetic Fields and Waves by the same authors, Fundamentals of Electromagnetic Phenomena capitalizes on the older text's traditional strengths--solid physics, inventive problems, and an experimental approach--while offering a briefer, more accessible introduction to the basic principles of electromagnetism.

  6. Correlative Tomography

    PubMed Central

    Burnett, T. L.; McDonald, S. A.; Gholinia, A.; Geurts, R.; Janus, M.; Slater, T.; Haigh, S. J.; Ornek, C.; Almuaili, F.; Engelberg, D. L.; Thompson, G. E.; Withers, P. J.

    2014-01-01

    Increasingly researchers are looking to bring together perspectives across multiple scales, or to combine insights from different techniques, for the same region of interest. To this end, correlative microscopy has already yielded substantial new insights in two dimensions (2D). Here we develop correlative tomography where the correlative task is somewhat more challenging because the volume of interest is typically hidden beneath the sample surface. We have threaded together x-ray computed tomography, serial section FIB-SEM tomography, electron backscatter diffraction and finally TEM elemental analysis all for the same 3D region. This has allowed observation of the competition between pitting corrosion and intergranular corrosion at multiple scales revealing the structural hierarchy, crystallography and chemistry of veiled corrosion pits in stainless steel. With automated correlative workflows and co-visualization of the multi-scale or multi-modal datasets the technique promises to provide insights across biological, geological and materials science that are impossible using either individual or multiple uncorrelated techniques. PMID:24736640

  7. The continuing challenge of electromagnetic launch

    SciTech Connect

    Cowan, M.; Cnare, E.C.; Duggin, B.W.; Kaye, R.J.; Marder, B.M.; Shokair, I.R.

    1993-07-01

    Interest in launching payloads through the atmosphere to ever higher velocity is robust. For hundreds of years, guns and rockets have been improved for this purpose until they are now considered to be near to their performance limits. While the potential of electromagnetic technology to increase launch velocity has been known since late in the nineteenth century, it was not until about 1980 that a sustained and large-scale effort was started to exploit it. Electromagnetic launcher technology is restricted here to mean only that technology which establishes both a current density, J, and a magnetic field, B, within a part of the launch package, called the armature, so that J {times} B integrated over the volume of the armature is the launching force. Research and development activity was triggered by the discovery that high velocity can be produced with a simple railgun which uses an arc for its armature. This so called ``plasma-armature railgun`` has been the launcher technology upon which nearly all of the work has focused. Still, a relatively small parallel effort has also been made to explore the potential of electromagnetic launchers which do not use sliding contacts on stationary rails to establish current in the armature. One electromagnetic launcher of this type is called an induction coilgun because armature current is established by electromagnetic induction. In this paper, we first establish terminology which we will use not only to specify requirements for successful endoatmospheric launch but also to compare different launcher types. Then, we summarize the statuses of the railgun and induction coilgun technologies and discuss the issues which must be resolved before either of these launchers can offer substantial advantage for endoatomospheric launch.

  8. Velocity damper for electromagnetically levitated materials

    DOEpatents

    Fox, Richard J.

    1994-01-01

    A system for damping oscillatory and spinning motions induced in an electromagnetically levitated material. Two opposed field magnets are located orthogonally to the existing levitation coils for providing a DC quadrupole field (cusp field) around the material. The material used for generating the DC quadrupole field must be nonconducting to avoid eddy-current heating and of low magnetic permeability to avoid distorting the induction fields providing the levitation.

  9. Velocity damper for electromagnetically levitated materials

    DOEpatents

    Fox, R.J.

    1994-06-07

    A system for damping oscillatory and spinning motions induced in an electromagnetically levitated material is disclosed. Two opposed field magnets are located orthogonally to the existing levitation coils for providing a DC quadrupole field (cusp field) around the material. The material used for generating the DC quadrupole field must be nonconducting to avoid eddy-current heating and of low magnetic permeability to avoid distorting the induction fields providing the levitation. 1 fig.

  10. Principles of electromagnetic theory

    SciTech Connect

    Kovetz, A.H. )

    1990-01-01

    This book emphasizes the fundamental understanding of the laws governing the behavior of charge and current carrying bodies. Electromagnetism is presented as a classical theory, based-like mechanics-on principles that are independent of the atomic constitution of matter. This book is unique among electromagnetic texts in its treatment of the precise manner in which electromagnetism is linked to mechanics and thermodynamics. Applications include electrostriction, piezoelectricity, ferromagnetism, superconductivity, thermoelectricity, magnetohydrodynamics, radiation from charged particles, electromagnetic wave propagation and guided waves. There are many worked examples of dynamical and thermal effects of electromagnetic fields, and of effects resulting from the motion of bodies.

  11. Induction linear accelerators

    NASA Astrophysics Data System (ADS)

    Birx, Daniel

    1992-03-01

    Among the family of particle accelerators, the Induction Linear Accelerator is the best suited for the acceleration of high current electron beams. Because the electromagnetic radiation used to accelerate the electron beam is not stored in the cavities but is supplied by transmission lines during the beam pulse it is possible to utilize very low Q (typically<10) structures and very large beam pipes. This combination increases the beam breakup limited maximum currents to of order kiloamperes. The micropulse lengths of these machines are measured in 10's of nanoseconds and duty factors as high as 10-4 have been achieved. Until recently the major problem with these machines has been associated with the pulse power drive. Beam currents of kiloamperes and accelerating potentials of megavolts require peak power drives of gigawatts since no energy is stored in the structure. The marriage of liner accelerator technology and nonlinear magnetic compressors has produced some unique capabilities. It now appears possible to produce electron beams with average currents measured in amperes, peak currents in kiloamperes and gradients exceeding 1 MeV/meter, with power efficiencies approaching 50%. The nonlinear magnetic compression technology has replaced the spark gap drivers used on earlier accelerators with state-of-the-art all-solid-state SCR commutated compression chains. The reliability of these machines is now approaching 1010 shot MTBF. In the following paper we will briefly review the historical development of induction linear accelerators and then discuss the design considerations.

  12. Method for imaging with low frequency electromagnetic fields

    DOEpatents

    Lee, Ki H.; Xie, Gan Q.

    1994-01-01

    A method for imaging with low frequency electromagnetic fields, and for interpreting the electromagnetic data using ray tomography, in order to determine the earth conductivity with high accuracy and resolution. The imaging method includes the steps of placing one or more transmitters, at various positions in a plurality of transmitter holes, and placing a plurality of receivers in a plurality of receiver holes. The transmitters generate electromagnetic signals which diffuse through a medium, such as earth, toward the receivers. The measured diffusion field data H is then transformed into wavefield data U. The traveltimes corresponding to the wavefield data U, are then obtained, by charting the wavefield data U, using a different regularization parameter .alpha. for each transform. The desired property of the medium, such as conductivity, is then derived from the velocity, which in turn is constructed from the wavefield data U using ray tomography.

  13. Method for imaging with low frequency electromagnetic fields

    DOEpatents

    Lee, K.H.; Xie, G.Q.

    1994-12-13

    A method is described for imaging with low frequency electromagnetic fields, and for interpreting the electromagnetic data using ray tomography, in order to determine the earth conductivity with high accuracy and resolution. The imaging method includes the steps of placing one or more transmitters, at various positions in a plurality of transmitter holes, and placing a plurality of receivers in a plurality of receiver holes. The transmitters generate electromagnetic signals which diffuse through a medium, such as earth, toward the receivers. The measured diffusion field data H is then transformed into wavefield data U. The travel times corresponding to the wavefield data U, are then obtained, by charting the wavefield data U, using a different regularization parameter [alpha] for each transform. The desired property of the medium, such as conductivity, is then derived from the velocity, which in turn is constructed from the wavefield data U using ray tomography. 13 figures.

  14. Measurement and control systems for an imaging electromagnetic flow metre.

    PubMed

    Zhao, Y Y; Lucas, G; Leeungculsatien, T

    2014-03-01

    Electromagnetic flow metres based on the principles of Faraday's laws of induction have been used successfully in many industries. The conventional electromagnetic flow metre can measure the mean liquid velocity in axisymmetric single phase flows. However, in order to achieve velocity profile measurements in single phase flows with non-uniform velocity profiles, a novel imaging electromagnetic flow metre (IEF) has been developed which is described in this paper. The novel electromagnetic flow metre which is based on the 'weight value' theory to reconstruct velocity profiles is interfaced with a 'Microrobotics VM1' microcontroller as a stand-alone unit. The work undertaken in the paper demonstrates that an imaging electromagnetic flow metre for liquid velocity profile measurement is an instrument that is highly suited for control via a microcontroller.

  15. Ocean acoustic tomography

    NASA Astrophysics Data System (ADS)

    Cornuelle, Bruce D.; Worcester, Peter F.; Dzieciuch, Matthew A.

    2008-10-01

    Ocean acoustic tomography (OAT) was proposed in 1979 by Walter Munk and Carl Wunsch as an analogue to x-ray computed axial tomography for the oceans. The oceans are opaque to most electromagnetic radiation, but there is a strong acoustic waveguide, and sound can propagate for 10 Mm and more with distinct multiply-refracted ray paths. Transmitting broadband pulses in the ocean leads to a set of impulsive arrivals at the receiver which characterize the impulse response of the sound channel. The peaks observed at the receiver are assumed to represent the arrival of energy traveling along geometric ray paths. These paths can be distinguished by arrival time, and by arrival angle when a vertical array of receivers is available. Changes in ray arrival time can be used to infer changes in ocean structure. Ray travel time measurements have been a mainstay of long-range acoustic measurements, but the strong sensitivity of ray paths to range-dependent sound speed perturbations makes the ray sampling functions uncertain in real cases. In the ray approximation travel times are sensitive to medium changes only along the corresponding eigenrays. Ray theory is an infinite-frequency approximation, and its eikonal equation has nonlinearities not found in the acoustic wave equation. We build on recent seismology results (kernels for body wave arrivals in the earth) to characterize the kernel for converting sound speed change in the ocean to travel time changes using more complete propagation physics. Wave-theoretic finite frequency kernels may show less sensitivity to small-scale sound speed structure.

  16. Mars Methane Analogue Mission (M3): Near Subsurface Electromagnetic Techniques and Analysis

    NASA Astrophysics Data System (ADS)

    Boivin, A.; Samson, C.; Holladay, J. S.; Cloutis, E. A.; Ernst, R. E.

    2012-03-01

    As part of the Canadian Space Agency's Mars Methane Analogue Mission, a micro-rover mission, an Electromagnetic Induction Sounder (EMIS) was used with the goal of demonstrating its value as a potential science instrument onboard future rovers.

  17. Results from the FELIX experiments on electromagnetic effects in hollow cylinders

    SciTech Connect

    Turner, L.R.; Gunderson, G.R.; Knott, M.J.; McGhee, D.G.; Praeg, W.F.; Wehrle, R.B.

    1985-01-01

    The early experiments with the FELIX (Fusion Electromagnetic Induction eXperiments) facility have been devoted to obtaining data which can be used to validate eddy current computer codes. This paper describes experiments on field variation inside conducting cylinders.

  18. Electromagnetic forming of aluminium alloy sheet

    NASA Astrophysics Data System (ADS)

    Oliveira, D. A.; Worswick, M.

    2003-09-01

    A numerical method for modeling the high rate deformation and impact that occurs during the electromagnetic forming process is presented with supporting experimental data, used to validate the predictions. The numerical model employs “loose" two-way coupling of the electromagnetic analysis with the elastic-plastic structural analysis. An electromagnetic finite element code is used to model the time varying currents that are discharged through the coil in order to obtain the transient magnetic forces that are imparted to the workpiece. The body forces generated by electromagnetic induction are then used as the loading condition to model the high rate deformation of the workpiece using an explicit dynamic finite element code. A series of high rate electromagnetic forming experiments are performed on 1 and 1.6 mm AA5754 and 1 mm AA5182 aluminum alloy sheet. The experiments consider free forming, while also serving as a basis to validate the predictive capability of the numerical models. The experiments exhibited high rate formability limits that were similar to conventional quasistatic forming limits. The numerical model accurately predicted the final geometry of the samples as well as the measured strain distributions.

  19. Induction synchrotron

    NASA Astrophysics Data System (ADS)

    Takayama, Ken; Kishiro, Junichi

    2000-08-01

    A novel proton synchrotron employing induction cells instead of radio frequency cavities is proposed. The major feature of the barrier bucket acceleration, where acceleration and longitudinal focusing are independently achieved is theoretically discussed with the help of multi-particle simulations. It is proved that barrier bucket acceleration allows ultimate use of longitudinal phase-space and is quite effective to substantially increase the beam intensity in synchrotrons. Engineering aspects of key devices to realize the novel synchrotron, a ferri/ferro-magnetic material loaded induction cell and a modulator being rapidly switched in synchronization with beam acceleration are described in detail. The idea is applied to an existing machine (the KEK 12 GeV-PS) and high-intensity proton rings such as JHF, ESS, and SNS and their predicted improvement in machine performance is given with numerical values for each case.

  20. Induction machine

    DOEpatents

    Owen, Whitney H.

    1980-01-01

    A polyphase rotary induction machine for use as a motor or generator utilizing a single rotor assembly having two series connected sets of rotor windings, a first stator winding disposed around the first rotor winding and means for controlling the current induced in one set of the rotor windings compared to the current induced in the other set of the rotor windings. The rotor windings may be wound rotor windings or squirrel cage windings.

  1. Polarized electromagnetic response of the moon

    NASA Technical Reports Server (NTRS)

    Sonett, C. P.; Smith, B. F.; Colburn, D. S.; Schubert, G.; Schwartz, K.

    1974-01-01

    The strong anisotropy in Apollo 15 Lunar Surface Magnetometer (LSM) signals resulting from electromagnetic induction in the moon, forced by fluctuations of the interplanetary magnetic field, is shown to result from intense polarization of the induced field. Arguments are given to show that the anisotropy cannot be explained wholly by asymmetric lunar induction in the presence of the diamagnetic cavity, but must be related to a regional influence. The weaker Apollo 12 anisotropy may also be associated with a regional influence. The site of Apollo 15 LSM at the edge of the Imbrium Basin suggests a preliminary model for calculations based on the possibility that Imbrium and perhaps Serenitatis are sources of the regional effect. Lastly, since the very low frequency induction seems free of the anisotropy, our earlier estimate of deep conductivity remains unchanged.

  2. Electromagnetic braking for Mars spacecraft

    NASA Technical Reports Server (NTRS)

    Holt, A. C.

    1986-01-01

    Aerobraking concepts are being studied to improve performance and cost effectiveness of propulsion systems for Mars landers and Mars interplanetary spacecraft. Access to megawatt power levels (nuclear power coupled to high-storage inductive or capacitive devices) on a manned Mars interplanetary spacecraft may make feasible electromagnetic braking and lift modulation techniques which were previously impractical. Using pulsed microwave and magnetic field technology, potential plasmadynamic braking and hydromagnetic lift modulation techniques have been identified. Entry corridor modulation to reduce loads and heating, to reduce vertical descent rates, and to expand horizontal and lateral landing ranges are possible benefits. In-depth studies are needed to identify specific design concepts for feasibility assessments. Standing wave/plasma sheath interaction techniques appear to be promising. The techniques may require some tailoring of spacecraft external structures and materials. In addition, rapid response guidance and control systems may require the use of structurally embedded sensors coupled to expert systems or to artificial intelligence systems.

  3. Review of Terahertz Tomography Techniques

    NASA Astrophysics Data System (ADS)

    Guillet, J. P.; Recur, B.; Frederique, L.; Bousquet, B.; Canioni, L.; Manek-Hönninger, I.; Desbarats, P.; Mounaix, P.

    2014-04-01

    Terahertz and millimeter waves penetrate various dielectric materials, including plastics, ceramics, crystals, and concrete, allowing terahertz transmission and reflection images to be considered as a new imaging tool complementary to X-Ray or Infrared. Terahertz imaging is a well-established technique in various laboratory and industrial applications. However, these images are often two-dimensional. Three-dimensional, transmission-mode imaging is limited to thin samples, due to the absorption of the sample accumulated in the propagation direction. A tomographic imaging procedure can be used to acquire and to render three-dimensional images in the terahertz frequency range, as in the optical, infrared or X-ray regions of the electromagnetic spectrum. In this paper, after a brief introduction to two dimensional millimeter waves and terahertz imaging we establish the principles of tomography for Terahertz Computed tomography (CT), tomosynthesis (TS), synthetic aperture radar (SAR) and time-of-flight (TOF) terahertz tomography. For each technique, we present advantages, drawbacks and limitations for imaging the internal structure of an object.

  4. Electromagnetic imaging with atomic magnetometers: a novel approach to security and surveillance

    NASA Astrophysics Data System (ADS)

    Hussain, Sarah; Marmugi, Luca; Deans, Cameron; Renzoni, Ferruccio

    2016-05-01

    We describe our research programme on the use of atomic magnetometers to detect conductive objects via electromagnetic induction. The extreme sensitivity of atomic magnetometers at low frequencies, up to seven orders of magnitude higher than a coil-based system, permits deep penetration through different media and barriers, and in various operative environments. This eliminates the limitations usually associated with electromagnetic detection.

  5. Measurements of reactor-relevant electromagnetic effects with the FELIX facility

    SciTech Connect

    Turner, L.R.; Hua, T.Q.; Knott, M.J.; Lee, S.Y.; McGhee, D.G.; Wehrle, R.B.

    1986-11-01

    Recent experiments with the FELIX (Fusion Electromagnetic Induction eXperiment) facility at Argonne National Laboratory (ANL) suggest that the expected electromagnetic forces and torques in a tokamak first wall, blanket, and shield (FWBS) system can be modelled by a single eddy current mode, with a simple characterization.

  6. Electromagnetic Radiation Analysis

    DTIC Science & Technology

    1978-04-10

    A methodology is given for determining whether electromagnetic radiation of sufficient strength to cause performance degradation to the test item...exists at the test item location. The results of an electromagnetic radiation effects test are used to identify the radio frequencies and electromagnetic ... radiation levels to which the test item is susceptible. Further, using a test bed, comparisons are made with the representative signal levels to

  7. Electromagnetic Compatibility in the Defense Systems of Future Years

    DTIC Science & Technology

    2002-06-01

    for Scattering and Absorption by Dielectric Objects. Proc. IEEE, vol. 70, N° 11, Nov.1982. [8-2] Y. Leviatan and A. Boag Analysis of Electromagnetic... Leviatan , P.G. Li, A.J. Adam, and J. Perini Single-Post Inductive Obstacle in Rectangular Waveguide. IEEE Trans. Microwave Theory and Tech., vol. MTT

  8. Introducing Electromagnetic Field Momentum

    ERIC Educational Resources Information Center

    Hu, Ben Yu-Kuang

    2012-01-01

    I describe an elementary way of introducing electromagnetic field momentum. By considering a system of a long solenoid and line charge, the dependence of the field momentum on the electric and magnetic fields can be deduced. I obtain the electromagnetic angular momentum for a point charge and magnetic monopole pair partially through dimensional…

  9. Tunability enhanced electromagnetic wiggler

    DOEpatents

    Schlueter, Ross D.; Deis, Gary A.

    1992-01-01

    The invention discloses a wiggler used in synchrotron radiation sources and free electron lasers, where each pole is surrounded by at least two electromagnetic coils. The electromagnetic coils are energized with different amounts of current to provide a wide tunable range of the on-axis magnetic flux density, while preventing magnetic saturation of the poles.

  10. Tunability enhanced electromagnetic wiggler

    DOEpatents

    Schlueter, R.D.; Deis, G.A.

    1992-03-24

    The invention discloses a wiggler used in synchrotron radiation sources and free electron lasers, where each pole is surrounded by at least two electromagnetic coils. The electromagnetic coils are energized with different amounts of current to provide a wide tunable range of the on-axis magnetic flux density, while preventing magnetic saturation of the poles. 14 figs.

  11. Electromagnetically Operated Counter

    DOEpatents

    Goldberg, H D; Goldberg, M I

    1951-12-18

    An electromagnetically operated counter wherein signals to be counted are applied to cause stepwise rotation of a rotatable element which is connected to a suitable register. The mechanism involved consists of a rotatable armature having three spaced cores of magnetic material and a pair of diametrically opposed electromagnets with a suitable pulsing circuit to actuate the magnets.

  12. Electromagnetic nonuniformly correlated beams.

    PubMed

    Tong, Zhisong; Korotkova, Olga

    2012-10-01

    A class of electromagnetic sources with nonuniformly distributed field correlations is introduced. The conditions on source parameters guaranteeing that the source generates a physical beam are derived. It is shown that the new sources are capable of producing beams with polarization properties that evolve on propagation in a manner much more complex compared to the well-known electromagnetic Gaussian Schell-model beams.

  13. Insights into electromagnetic interaction mechanisms.

    PubMed

    Goodman, Reba; Blank, Martin

    2002-07-01

    Low frequency (< 300 Hz) electromagnetic (EM) fields induce biological changes that include effects ranging from increased enzyme reaction rates to increased transcript levels for specific genes. The induction of stress gene HSP70 expression by exposure to EM fields provides insight into how EM fields interact with cells and tissues. Insights into the mechanism(s) are also provided by examination of the interaction of EM fields with moving charges and their influence on enzyme reaction rates in cell-free systems. Biological studies with in vitro model systems have focused, in general, on the nature of the signal transduction pathways involved in response to EM fields. It is likely, however, that EM fields also interact directly with electrons in DNA to stimulate biosynthesis. Identification of an EM field-sensitive DNA sequence in the heat shock 70 (HSP70) promoter, points to the application of EM fields in two biomedical applications: cytoprotection and gene therapy. EM field induction of the stress protein hsp70 may also provide a useful biomarker for establishing a science-based safety standard for the design of cell phones and their transmission towers.

  14. Photoacoustic Tomography

    NASA Astrophysics Data System (ADS)

    Wang, Lihong V.

    Photoacoustic tomography (PAT) refers to imaging that is based on the photoacoustic effect. Although the photoacoustic effect as a physical phenomenon was first reported on by Alexander Graham Bell in 1880 [1], PAT as an imaging technology was developed only after the advent of ultrasonic transducers, computers, and lasers [2-31]. A review on biomedical photoacoustics is available [32]. The motivation for PAT is to combine optical-absorption contrast with ultrasonic spatial resolution for deep imaging in the optical quasi-diffusive or diffusive regime. In PAT, the tissue is irradiated by usually a short-pulsed laser beam to achieve a thermal and acoustic impulse response (Fig. 19.1). Locally absorbed light is converted into heat, which is further converted to a pressure rise via thermo-elastic expansion. The initial pressure rise - determined by the local optical absorption coefficient (μ â ), fluence (ψ) and other thermal and mechanical properties - propagates as an ultrasonic wave, which is referred to as a photoacoustic wave.

  15. Measurement system design of an imaging electromagnetic flow meter

    NASA Astrophysics Data System (ADS)

    Zhao, Y. Y.; Lucas, G.; Leeungculsatien, T.; Zhang, T.

    2012-03-01

    Electromagnetic flow meters based on the principles of Faraday's laws of induction have been used successfully in many industries. In order to achieve velocity profile measurements in single phase and multiphase flows with non-uniform velocity profiles, a novel Imaging Electromagnetic Flow meter (IEF) has been developed which is described in this paper. The novel electromagnetic flow meter uses a microcontroller as the processing core to achieve the function of driving the uniform magnetic field, acquiring voltage signals with electronic system, matrix inversion calculation and result display. The work undertaken in the paper demonstrates that an imaging electromagnetic flow meter for liquid velocity profile measurement is an instrument that is highly suited for control via a microcontroller.

  16. Linear induction pump

    DOEpatents

    Meisner, John W.; Moore, Robert M.; Bienvenue, Louis L.

    1985-03-19

    Electromagnetic linear induction pump for liquid metal which includes a unitary pump duct. The duct comprises two substantially flat parallel spaced-apart wall members, one being located above the other and two parallel opposing side members interconnecting the wall members. Located within the duct are a plurality of web members interconnecting the wall members and extending parallel to the side members whereby the wall members, side members and web members define a plurality of fluid passageways, each of the fluid passageways having substantially the same cross-sectional flow area. Attached to an outer surface of each side member is an electrically conductive end bar for the passage of an induced current therethrough. A multi-phase, electrical stator is located adjacent each of the wall members. The duct, stators, and end bars are enclosed in a housing which is provided with an inlet and outlet in fluid communication with opposite ends of the fluid passageways in the pump duct. In accordance with a preferred embodiment, the inlet and outlet includes a transition means which provides for a transition from a round cross-sectional flow path to a substantially rectangular cross-sectional flow path defined by the pump duct.

  17. Radar tomography of bridge decks

    NASA Astrophysics Data System (ADS)

    Davidson, Nigel C.; Chase, Steven B.

    1998-03-01

    This paper presents the development of ground-penetrating radar bridge deck inspection systems sponsored by the Federal Highway Administration. Two radar systems have been designed and built by Lawrence Livermore National Laboratory. The HERMES bridge inspector (High-speed Electromagnetic Roadway Mapping and Evaluation System) is designed to survey the deck condition during normal traffic flow. Thus the need for traffic control during inspection is eliminated. This system employs a 64 channel antenna array covering 1.9 m in width with a sampling density of 3 cm. To investigate areas of a bridge deck that are of particular interest and require detailed inspection a slower, cart mounted radar has been produced. This system is named PERES (Precision Electromagnetic Roadway Evaluation System). The density of data coverage with PERES is 1 cm and an average or 100 samples is taken at each location to improve the signal to noise ratio. Images of the deck interior are reconstructed from the original data using synthetic aperture tomography. The target of these systems is the location of steel reinforcement, corrosion related delaminations, voids and disbonds. The final objective is for these, and other non-destructive technologies, to provide information on the condition of the nation's bridges so that funds will be spent on the structures in most need of repair.

  18. Electromagnetism in the Movies.

    ERIC Educational Resources Information Center

    Everitt, Lori R.; Patterson, Evelyn T.

    1999-01-01

    Describes how the authors used portions of popular movies to help students review concepts related to electromagnetism. Movies used and concepts covered in the review are listed, and a sample activity is described. (WRM)

  19. An opening electromagnetic transducer

    NASA Astrophysics Data System (ADS)

    Sun, Yanhua; Kang, Yihua

    2013-12-01

    Tubular solenoids have been widely used without any change since an electrical wire was discovered to create magnetic fields by Hans Christian Oersted in 1820 and thereby the wire was first coiled as a helix into a solenoid coil by William Sturgeon in 1823 and was improved by Joseph Henry in 1829 [see http://www.myetymology.com/encyclopedia/History_of_the_electricity.html; J. M. D. Coey, Magnetism and Magnetic Materials (Cambridge University Press, New York, 2010); and F. Winterberg, Plasma Phys. 8, 541553 (1996)]. A magnetic control method of C-shaped carrying-current wire is proposed, and thereby a new opening electromagnetic transducer evidently differing from the traditional tubular solenoid is created, capable of directly encircling and centering the acted objects in it, bringing about convenient and innovative electromagnetic energy conversion for electromagnetic heating, electromagnetic excitation, physical information capture, and electro-mechanical motion used in science research, industry, and even biomedical activities.

  20. Numerical calculation of primary slot leakage inductance of a Single-sided HTS linear induction motor used for linear metro

    NASA Astrophysics Data System (ADS)

    Li, Dong; Wen, Yinghong; Li, Weili; Fang, Jin; Cao, Junci; Zhang, Xiaochen; Lv, Gang

    2017-03-01

    In the paper, the numerical method calculating asymmetric primary slot leakage inductances of Single-sided High-Temperature Superconducting (HTS) Linear Induction Motor (HTS LIM) is presented. The mathematical and geometric models of three-dimensional nonlinear transient electromagnetic field are established and the boundary conditions are also given. The established model is solved by time-stepping Finite Element Method (FEM). Then, the three-phase asymmetric primary slot leakage inductances under different operation conditions are calculated by using the obtained electromagnetic field distribution. The influences of the special effects such as longitudinal end effects, transversal edge effects, etc. on the primary slot leakage inductance are investigated. The presented numerical method is validated by experiments carried out on a 3.5 kW prototype with copper wires which has the same structures with the HTS LIM.

  1. Electromagnetic rotational actuation.

    SciTech Connect

    Hogan, Alexander Lee

    2010-08-01

    There are many applications that need a meso-scale rotational actuator. These applications have been left by the wayside because of the lack of actuation at this scale. Sandia National Laboratories has many unique fabrication technologies that could be used to create an electromagnetic actuator at this scale. There are also many designs to be explored. In this internship exploration of the designs and fabrications technologies to find an inexpensive design that can be used for prototyping the electromagnetic rotational actuator.

  2. Electromagnetic energy transport in RFP magnetic relaxation

    NASA Astrophysics Data System (ADS)

    McCollam, K. J.; Thuecks, D. J.; Stone, D. R.; Anderson, J. K.; den Hartog, D. J.; Duff, J.; Ko, J.; Kumar, S.; Parke, E.; Lin, L.; Brower, D. L.; Ding, W. X.

    2014-10-01

    In an RFP driven by steady toroidal induction, tearing modes responsible for magnetic relaxation redistribute electromagnetic energy throughout the plasma, generating the net EMF that regulates the equilibrium profile. In MST experiments, insertable edge probes measure local fluctuations in electric and magnetic fields, from which flux-surface-average Poynting flux is derived. This outwardly directed flux is maximum during discrete ``sawtooth'' magnetic relaxation events and is a significant fraction (a few 10s of percent) of the total input inductive power when averaged over time. Spatially, the flux is maximum at the reversal surface and decreases outside, indicating that transported energy is deposited at the plasma edge. These results are similar to expectations from a simple model of an incompressible fluid plasma with a resistive boundary and consistent with estimates of global power balance from time-resolved equilibrium reconstructions. This work was supported by the US DOE and NSF.

  3. Instability in electromagnetically driven flows. II

    NASA Astrophysics Data System (ADS)

    Rodriguez Imazio, Paola; Gissinger, Christophe

    2016-03-01

    In a previous paper, we have reported numerical simulations of the magnetohydrodynamic flow driven by a travelling magnetic field in an annular channel, at low Reynolds number. It was shown that the stalling of such induction pump is strongly related to magnetic flux expulsion. In the present article, we show that for larger hydrodynamic Reynolds number, and with more realistic boundary conditions, this instability takes the form of a large axisymmetric vortex flow in the (r, z)-plane, in which the fluid is locally pumped in the direction opposite to the one of the magnetic field. Close to the marginal stability of this vortex flow, a low-frequency pulsation is generated. Finally, these results are compared to theoretical predictions and are discussed within the framework of experimental annular linear induction electromagnetic pumps.

  4. Armature design for coaxial induction launchers

    SciTech Connect

    Andrews, J.A.; Devine, J.R. . Center for Electromechanics)

    1991-01-01

    This paper reports on the armature design for a coaxial induction launcher that is influenced by a large set of highly coupled parameters. The simplifying assumptions often employed in coaxial accelerator analysis, such as a uniform or sinusoidal axial distribution of the azimuthal armature current, are unrealistic in induction launchers with monolithic single-turn armatures. In order to better understand the true dynamic behavior of coaxial accelerators, the Center for Electromechanics at The University of Texas at Austin (CEM-UT) has developed series of computer codes based on the current filament method. By utilizing these performance codes in conjunction with electromagnetic (EM) and mechanical finite element programs, it is now possible to design high performance induction launchers with armatures that can withstand the considerable mechanical and thermal loads inherent in a coaxial accelerator launch.

  5. Effect of the rate of temperature increase on water quality during heating in electromagnetic- and gas-heated pans.

    PubMed

    Hiratsuka, Hiroshi; Sasaki, Ken

    2004-04-01

    More rapid increases in the pH value and hardness during electromagnetic heating of a pan of water were observed than when the pan was heated by LNG or LPG. The water quality changed universally in several tap water samples across Japan. This quality change was closely correlated with the rate of temperature increase, irrespective of heating by electromagnetic induction, LNG or LPG.

  6. Design, fabrication and characterization of LTCC-based electromagnetic microgenerators

    NASA Astrophysics Data System (ADS)

    Gierczak, M.; Markowski, P.; Dziedzic, A.

    2016-02-01

    Design, manufacturing process and properties of electromagnetic microgenerators fabricated in LTCC (Low Temperature Co-fired Ceramics) technology are presented in this paper. Electromagnetic microgenerators consist of planar coils spatially arranged on several layers of LTCC and of a multipole permanent magnet. Two different patterns of coils with 2-, 8-,10- and 12-layers and outer diameter of 50 mm were designed and fabricated. Silver-based pastes ESL 903-A or DuPont 6145 were used. In order to estimate the inductance of a single spatial coil the Greenhouse (self-inductance) and Hoer (mutual inductance) calculation methods were used. To verify the calculation results a single-layer coil was fabricated for each pattern and its inductance was measured using the precision RLC Meter. Fabricated LTCC microgenerators with embedded coils allow to generate voltage higher than ten volts and the electrical output power of approximately 600 mW at the rotor rotation speed of 12 thousands rpm. The self-made system was used for characterization of LTCC-based electromagnetic microgenerators.

  7. Faraday's Investigation of Electromagnetic Induction. Experiment No. 21.

    ERIC Educational Resources Information Center

    Devons, Samuel

    This paper focuses on Michael Faraday's experimental research in electricity in the 1830's. Historical notes related to his work are included as well as experiments, his objectives, and illustrations of equipment for the experiments. Examples from his diary are given so that students can attempt to emulate his honest and systematic manner of…

  8. Ultra-Wideband Electromagnetic Induction for UXO Discrimination

    DTIC Science & Technology

    2002-11-30

    prolate to oblate shapes do not present problematical considerations, we will just proceed below in terms of the prolate case. The coefficients bpmn in...these equations are known in the sense that they are calculated from the primary field, while the unknown Bpmn must be solved for. Obtaining the... Bpmn constitutes solving the problem, given that the associated Legendre functions m mn nandP Q are readily evaluated. A set of bpmn can be obtained

  9. Electromagnetic induction in New Zealand: analogue model and field results

    NASA Astrophysics Data System (ADS)

    Chen, J.; Dosso, H. W.; Ingham, M.

    The behaviour of electric and magnetic variations over North Island (New Zealand) is studied with the aid of a laboratory analogue model. The source field frequencies used in the analogue modelling simulate naturally occurring geomagnetic variations of 5-120 min periods. In-phase and quadrature magnetic and electric fields for a selection of traverses for the modelled region of North Island are presented. Since North Island is of a relatively narrow cross-section, the field responses, even for inland locations, are expected to show strongly the effects of the surrounding ocean. The irregular coastlines, as well as the strait between North and South Islands, lead to coastal and inland field anomalies due to induced currents being deflected and channelled to produce localized current densities. The comparison of model results with field station measurements obtained earlier individually by Ingham and by Midha for sites in the northeastern, central, and southern (near Cook Strait) regions of North Island demonstrates the large role the ocean has in the observed field responses. Differences in the model and field results at some sites are expected and should reflect the effects of the local geology and the conductive substructure related to the complex tectonics of the region not simulated in the model.

  10. Electromagnetic Induction Sensing of UneXploded Ordnance with Pedemis

    DTIC Science & Technology

    2012-10-22

    Grzegorczykc, Pablo Fernándezb, and Kevin O’Neilla,b aUSACE-ERDC-CRREL, 72 Lyme Rd., Hanover, NH 03755, USA bThayer School of Engineering, Darthmouth...6] Grzegorczyk, T. M., Barrowes, B. E., Shubitidze, F., Fernandez , J. P., and O’Neill, K., “Simultane- ous identification of multiple unexploded...9] Shubitidze, F., Karkashadze, D., Fernandez , J. P., Barrowes, B. E., O’Neill, K., Grzegorczyk, and Shamatava, I., “Applying a volume dipole

  11. ALLTEM Multi-Axis Electromagnetic Induction System Demonstration and Validation

    DTIC Science & Technology

    2011-11-17

    directions (Hx and Hy). Because a transmitter is always on, opposite Rx loops are paired as gradiometers to cancel the primary field. ALLTEM APG...spatial data interval of 20 cm or less is used for each recorded channel along a line to ensure that each Rx gradiometer loop pair has more than one...record. Records for 19 Tx-Rx gradiometer channels (x, y, z, or diagonal, component of the magnetic field) are typically written at rates of 2.5 to 5

  12. Subsurface Electromagnetic Induction Imaging for Unexploded Ordnance Detection

    DTIC Science & Technology

    2012-01-01

    locations that contribute collectively but independently to the measured magnetic field . The polarizabilities of the dipoles are simultaneously updated in a...process that seeks to minimize the mismatch between computed and measured fields over a grid. In order to force the polarizabilities to be positive...discards or selects dipoles based on their influence on the measured field . Preliminary investigations indicate a fast convergence rate and the ability

  13. Electromagnetic Induction E-Sensor for Underwater UXO Detection

    DTIC Science & Technology

    2011-12-01

    EMF Electromotive force FET Field Effect Transitor Hz Hertz ms millisecond nV nanoVolt QFS QUASAR Federal...Instead this electrode couples capacitively to the local electric potential. A series of deep ocean tests in locations from Australia to the Gulf of... series resistance of the coil was also reduced by 1/3, so though the number of turns went down, the drive current went up; leaving magnetic moment

  14. Improved Magnetic Fusion Energy Economics via Massive Resistive Electromagnets

    SciTech Connect

    Woolley, R.D.

    1998-08-19

    Abandoning superconductors for magnetic fusion reactors and instead using resistive magnet designs based on cheap copper or aluminum conductor material operating at "room temperature" (300 K) can reduce the capital cost per unit fusion power and simplify plant operations. By increasing unit size well beyond that of present magnetic fusion energy conceptual designs using superconducting electromagnets, the recirculating power fraction needed to operate resistive electromagnets can be made as close to zero as needed for economy without requiring superconductors. Other advantages of larger fusion plant size, such as very long inductively driven pulses, may also help reduce the cost per unit fusion power.

  15. Field studies in geophysical diffraction tomography

    SciTech Connect

    Witten, A.J.; Stevens, S.S. ); King, W.C. . Dept. of Geography and Environmental Engineering); Ursic, J.R. . Region V)

    1992-01-01

    Geophysical diffraction tomography (GDT) is a quantitative, high- resolution technique for subsurface imaging. This method has been used in a number of shallow applications to image buried waste, trenches, soil strata, tunnels, synthetic magma chambers, and the buried skeletal remains of seismosaurus, the longest dinosaur ever discovered. The theory associated with the GDT inversion and implementing software have been developed for acoustic and scalar electromagnetic waves for bistatic and monostatic measurements in cross-borehole, offset vertical seismic profiling and reflection geometries. This paper presents an overview of some signal processing algorithms, a description of the instrumentation used in field studies, and selected imaging results.

  16. Field studies in geophysical diffraction tomography

    SciTech Connect

    Witten, A.J.; Stevens, S.S.; King, W.C.; Ursic, J.R.

    1992-07-01

    Geophysical diffraction tomography (GDT) is a quantitative, high- resolution technique for subsurface imaging. This method has been used in a number of shallow applications to image buried waste, trenches, soil strata, tunnels, synthetic magma chambers, and the buried skeletal remains of seismosaurus, the longest dinosaur ever discovered. The theory associated with the GDT inversion and implementing software have been developed for acoustic and scalar electromagnetic waves for bistatic and monostatic measurements in cross-borehole, offset vertical seismic profiling and reflection geometries. This paper presents an overview of some signal processing algorithms, a description of the instrumentation used in field studies, and selected imaging results.

  17. Demonstration of Lenz's Law with an Induction Motor

    ERIC Educational Resources Information Center

    Kraftmakher, Yaakov

    2005-01-01

    The interaction of a conductor with a time-dependent magnetic field is an important topic of electromagnetic theory. A computerized classroom demonstration shows how the eddy currents induced in the rotor of an induction motor cause its rotation or braking. Both phenomena are directly related to Lenz's law.

  18. Axial-Gap Induction Motor For Levitated Specimens

    NASA Technical Reports Server (NTRS)

    Sridharan, Govind; Rhim, Won-Kyu; Barber, Dan; Chung, Sang

    1992-01-01

    Motor does not obscure view of specimen. Axial-gap induction motor applies torque to rotate electrostatically or electromagnetically levitated specimen of metal. Possible applications include turning specimens for uniform heating under focused laser beams and obtaining indirect measurements of resistivities or of surface tensions in molten specimens.

  19. Modeling of electromagnetic, fluid flow, and heat transfer phenomena in electromagnetic casting of aluminum

    SciTech Connect

    Bhamidipati, J.R.; El-Kaddah, N.

    1995-12-31

    A mathematical model for the analysis and design of electromagnetic continuous casters (EMC) has been developed. The model addresses all aspects of EMC operation, namely, electromagnetic confinement of the molten pool, and melt solidification, all in terms of basic process variables. A methodology is presented for solving the coupled electromagnetic, heat transfer and fluid flow equations without regridding the solution domain during the search for the equilibrium meniscus shape, which is not known a priori. It is based on the solution of these equations in a fixed computational domain using a variable non-orthogonal coordinate transformation. Within this framework, the electromagnetic field was computed using the technique of mutual inductance, while the temperature and velocity fields in the slab were calculated using the control volume technique. The equilibrium shape of the meniscus was determined from the balance between the magnetic, metallostatic, and surface tension pressures. The model was used to simulate EMC casting of aluminum, and the numerical predictions were found to be in excellent agreement with experimental measurements reported in the open literature. The model presented in this paper provides a theoretical framework for the analysis and optimization of EMC casters.

  20. Electromagnetic Basis of Metabolism and Heredity

    NASA Technical Reports Server (NTRS)

    Freund, Friedemann; Stolc, Viktor

    2016-01-01

    Living organisms control their cellular biological clocks to maintain functional oscillation of the redox cycle, also called the "metabolic cycle" or "respiratory cycle". Organization of cellular processes requires parallel processing on a synchronized time-base. These clocks coordinate the timing of all biochemical processes in the cell, including energy production, DNA replication, and RNA transcription. When this universal time keeping function is perturbed by exogenous induction of reactive oxygen species (ROS), the rate of metabolism changes. This causes oxidative stress, aging and mutations. Therefore, good temporal coordination of the redox cycle not only actively prevents chemical conflict between the reductive and oxidative partial reactions; it also maintains genome integrity and lifespan. Moreover, this universal biochemical rhythm can be disrupted by ROS induction in vivo. This in turn can be achieved by blocking the electron transport chain either endogenously or exogenously by various metabolites, e.g. hydrogen sulfide (H2S), highly diffusible drugs, and carbon monoxide (CO). Alternatively, the electron transport in vivo can be attenuated via a coherent or interfering transfer of energy from exogenous ultralow frequency (ULF) and extremely low frequency (ELF) electromagnetic (EM) fields, suggesting that-on Earth-such ambient fields are an omnipresent (and probably crucially important) factor for the time-setting basis of universal biochemical reactions in living cells. Our work demonstrated previously un-described evidence for quantum effects in biology by electromagnetic coupling below thermal noise at the universal electron transport chain (ETC) in vivo.

  1. Electromagnetic properties of baryons

    SciTech Connect

    Ledwig, T.; Pascalutsa, V.; Vanderhaeghen, M.; Martin-Camalich, J.

    2011-10-21

    We discuss the chiral behavior of the nucleon and {Delta}(1232) electromagnetic properties within the framework of a SU(2) covariant baryon chiral perturbation theory. Our one-loop calculation is complete to the order p{sup 3} and p{sup 4}/{Delta} with {Delta} as the {Delta}(1232)-nucleon energy gap. We show that the magnetic moment of a resonance can be defined by the linear energy shift only when an additional relation between the involved masses and the applied magnetic field strength is fulfilled. Singularities and cusps in the pion mass dependence of the {Delta}(1232) electromagnetic moments reflect a non-fulfillment. We show results for the pion mass dependence of the nucleon iso-vector electromagnetic quantities and present preliminary results for finite volume effects on the iso-vector anomalous magnetic moment.

  2. Aircraft electromagnetic compatibility

    NASA Technical Reports Server (NTRS)

    Clarke, Clifton A.; Larsen, William E.

    1987-01-01

    Illustrated are aircraft architecture, electromagnetic interference environments, electromagnetic compatibility protection techniques, program specifications, tasks, and verification and validation procedures. The environment of 400 Hz power, electrical transients, and radio frequency fields are portrayed and related to thresholds of avionics electronics. Five layers of protection for avionics are defined. Recognition is given to some present day electromagnetic compatibility weaknesses and issues which serve to reemphasize the importance of EMC verification of equipment and parts, and their ultimate EMC validation on the aircraft. Proven standards of grounding, bonding, shielding, wiring, and packaging are laid out to help provide a foundation for a comprehensive approach to successful future aircraft design and an understanding of cost effective EMC in an aircraft setting.

  3. Seismic electromagnetic study in China

    NASA Astrophysics Data System (ADS)

    Huang, Qinghua

    2016-04-01

    Seismo-electromagnetism is becoming a hot interdisciplinary study in both geosciences and electromagnetism. Numerous electromagnetic changes at a broad range of frequencies associated with earthquakes have been reported independently. There are some attempts of applying such electromagnetic data to short-term earthquake prediction. Although due to the complexity of seismogenic process and underground structure, the seismic electromagnetic phenomena cannot be fully understood, the seismic electromagnetic study plays a key role in the mitigation of seismic hazard. China is one of the countries which have the earliest reports on seismo-electromagnetic phenomena. The seismic electromagnetic study in China started in late 1960's. There are almost 50 years continuous observation data up to now, which provides a unique database for seismo-electromagnetic study not only in China, but also in the world. Therefore, seismo-electromagnetic study in China is interested broadly by international communities of geosciences and electromagnetism. I present here a brief review on seismic electromagnetic study in China, especially focusing on geo-electromagnetic observation and empirical prediction based on the observation data. After summarizing various electromagnetic observations such as apparent resistivity, geoelectric potential, geomagnetic field, electromagnetic disturbance, and so on, I show the cases of the empirical prediction based on the observed electromagnetic data associated with some earthquakes in China. Finally, based on the above review, I propose an integrated research scheme of earthquake-related electromagnetic phenomena, which includes the interaction between appropriate observations, robust methodology of data processing, and theoretical model analysis. This study is supported partially by the National Natural Science Foundation of China (41274075) and the National Basic Research Program of China (2014CB845903).

  4. Superconducting dipole electromagnet

    DOEpatents

    Purcell, John R.

    1977-07-26

    A dipole electromagnet of especial use for bending beams in particle accelerators is wound to have high uniformity of magnetic field across a cross section and to decrease evenly to zero as the ends of the electromagnet are approached by disposing the superconducting filaments of the coil in the crescent-shaped nonoverlapping portions of two intersecting circles. Uniform decrease at the ends is achieved by causing the circles to overlap increasingly in the direction of the ends of the coil until the overlap is complete and the coil is terminated.

  5. Improved Electromagnetic Brake

    NASA Technical Reports Server (NTRS)

    Martin, Toby B.

    2004-01-01

    A proposed design for an electromagnetic brake would increase the reliability while reducing the number of parts and the weight, relative to a prior commercially available electromagnetic brake. The reductions of weight and the number of parts could also lead to a reduction of cost. A description of the commercial brake is prerequisite to a description of the proposed electromagnetic brake. The commercial brake (see upper part of figure) includes (1) a permanent magnet and an electromagnet coil on a stator and (2) a rotor that includes a steel contact plate mounted, with tension spring loading, on an aluminum hub. The stator is mounted securely on a stationary object, which would ordinarily be the housing of a gear drive or a motor. The rotor is mounted on the shaft of the gear drive or motor. The commercial brake nominally operates in a fail-safe (in the sense of normally braking) mode: In the absence of current in the electromagnet coil, the permanent magnet pulls the contact plate, against the spring tension, into contact with the stator. To release the brake, one excites the electromagnet with a current of the magnitude and polarity chosen to cancel the magnetic flux of the permanent magnet, thereby enabling the spring tension to pull the contact plate out of contact with the stator. The fail-safe operation of the commercial brake depends on careful mounting of the rotor in relation to the stator. The rotor/stator gap must be set with a tolerance between 10 and 15 mils (between about 0.25 and about 0.38 mm). If the gap or the contact pad is thicker than the maximum allowable value, then the permanent magnetic field will not be strong enough to pull the steel plate across the gap. (For this reason, any contact pad between the contact plate and the stator must also be correspondingly thin.) If the gap exceeds the maximum allowable value because of shaft end play, it becomes impossible to set the brake by turning off the electromagnet current. Although it may

  6. Volcano-electromagnetic effects

    USGS Publications Warehouse

    Johnston, Malcolm J. S.

    2007-01-01

    Volcano-electromagnetic effects—electromagnetic (EM) signals generated by volcanic activity—derive from a variety of physical processes. These include piezomagnetic effects, electrokinetic effects, fluid vaporization, thermal demagnetization/remagnetization, resistivity changes, thermochemical effects, magnetohydrodynamic effects, and blast-excited traveling ionospheric disturbances (TIDs). Identification of different physical processes and their interdependence is often possible with multiparameter monitoring, now common on volcanoes, since many of these processes occur with different timescales and some are simultaneously identified in other geophysical data (deformation, seismic, gas, ionospheric disturbances, etc.). EM monitoring plays an important part in understanding these processes.

  7. Electromagnetic power absorber

    NASA Technical Reports Server (NTRS)

    Iwasaki, R. S. (Inventor)

    1979-01-01

    A structure is presented with a surface portion of dielectric material which passes electromagnetic radiation and with a portion below the surface which includes material that absorbs the radiation, the face of the structure being formed with numerous steep ridges. The steepness of the dielectric material results in a high proportion of the electromagnetic energy passing through the surface for absorption by the absorbing material under the surface. A backing of aluminum or other highly heat-conductive and reflective material lies under the face and has very steep protuberances supporting the absorbing and dielectric materials.

  8. Turbocharging Quantum Tomography

    SciTech Connect

    Blume-Kohout, Robin J.; Gamble, John King; Nielsen, Erik; Maunz, Peter Lukas Wilhelm; Scholten, Travis L.; Rudinger, Kenneth Michael

    2015-01-01

    Quantum tomography is used to characterize quantum operations implemented in quantum information processing (QIP) hardware. Traditionally, state tomography has been used to characterize the quantum state prepared in an initialization procedure, while quantum process tomography is used to characterize dynamical operations on a QIP system. As such, tomography is critical to the development of QIP hardware (since it is necessary both for debugging and validating as-built devices, and its results are used to influence the next generation of devices). But tomography suffers from several critical drawbacks. In this report, we present new research that resolves several of these flaws. We describe a new form of tomography called gate set tomography (GST), which unifies state and process tomography, avoids prior methods critical reliance on precalibrated operations that are not generally available, and can achieve unprecedented accuracies. We report on theory and experimental development of adaptive tomography protocols that achieve far higher fidelity in state reconstruction than non-adaptive methods. Finally, we present a new theoretical and experimental analysis of process tomography on multispin systems, and demonstrate how to more effectively detect and characterize quantum noise using carefully tailored ensembles of input states.

  9. Modeling ferrite electromagnetic response in the time domain

    SciTech Connect

    Johnson, J.; DeFord, J.F.; Craig, G.D.

    1989-04-06

    The behavior of ferrite loads commonly found in induction accelertors has important consequences for the performance of these accelerators. Previous work by the authors on modeling the electromagnetic fields in induction cavities has focussed upon use of a simple, phenomenological model for the process of magnetization reversal in these ferrite loads. In this paper we consider a model for magnetization reversal which is more deeply rooted in theory, and present a simulation of the reversal process based upon this model for an idealized set of boundary conditions. 7 refs., 3 figs.

  10. Electromagnetic structure of light nuclei

    SciTech Connect

    Pastore, Saori

    2016-03-25

    Here, the present understanding of nuclear electromagnetic properties including electromagnetic moments, form factors and transitions in nuclei with A ≤ 10 is reviewed. Emphasis is on calculations based on nuclear Hamiltonians that include two- and three-nucleon realistic potentials, along with one- and two-body electromagnetic currents derived from a chiral effective field theory with pions and nucleons.

  11. "Hearing" Electromagnetic Waves

    ERIC Educational Resources Information Center

    Rojo, Marta; Munoz, Juan

    2014-01-01

    In this work, an educational experience is described in which a microwave communication link is used to make students aware that all electromagnetic waves have the same physical nature and properties. Experimental demonstrations are linked to theoretical concepts to increase comprehension of the physical principles underlying electromagnetic…

  12. Electromagnetic radiation detector

    DOEpatents

    Benson, Jay L.; Hansen, Gordon J.

    1976-01-01

    An electromagnetic radiation detector including a collimating window, a cathode member having a photoelectric emissive material surface angularly disposed to said window whereby radiation is impinged thereon at acute angles, an anode, separated from the cathode member by an evacuated space, for collecting photoelectrons emitted from the emissive cathode surface, and a negatively biased, high transmissive grid disposed between the cathode member and anode.

  13. Equivalence principles and electromagnetism

    NASA Technical Reports Server (NTRS)

    Ni, W.-T.

    1977-01-01

    The implications of the weak equivalence principles are investigated in detail for electromagnetic systems in a general framework. In particular, it is shown that the universality of free-fall trajectories (Galileo weak equivalence principle) does not imply the validity of the Einstein equivalence principle. However, the Galileo principle plus the universality of free-fall rotation states does imply the Einstein principle.

  14. Noncontact Electromagnetic Vibration Source

    NASA Technical Reports Server (NTRS)

    Namkung, Min; Fulton, James P.; Wincheski, Buzz A.

    1994-01-01

    Metal aircraft skins scanned rapidly in vibration tests. Relatively simple combination of permanent magnets and electromagnet serves as noncontact vibration source for nondestructive testing of metal aircraft skins. In test, source excites vibrations, and vibration waveforms measured, then analyzed for changes in resonances signifying cracks and other flaws.

  15. Simple Superconducting "Permanent" Electromagnet

    NASA Technical Reports Server (NTRS)

    Israelson, Ulf E.; Strayer, Donald M.

    1992-01-01

    Proposed short tube of high-temperature-superconducting material like YBa2Cu3O7 acts as strong electromagnet that flows as long as magnetic field remains below critical value and temperature of cylinder maintained sufficiently below superconducting-transition temperature. Design exploits maximally anisotropy of high-temperature-superconducting material.

  16. Optical electromagnetic radiation detector

    NASA Astrophysics Data System (ADS)

    Miceli, W. J.; Ludman, J. E.

    1985-08-01

    An optical electromagnetic radiation detector is invented having a probe for receiving nearby electromagnetic radiation. The probe includes a loop antenna connected to a pair of transparent electrodes deposited on the end surfaces of an electro-optic Fabry-Perot interferometer. When the loop antenna picks up the presence of electromagnetic radiation, a voltage will be developed across the crystal of the electro-optic Fabry-Perot interferometer thereby changing the optical length of the interferometer. A beam of light from a remote location is transmitted through an optical fiber onto the Fabry-Perot interferometer. The change in optical length of the Fabry-Perot interferometer alters the intensity of the beam of light as its is reflected from the Fabry-Perot interferometer back through the optical fiber to the remote location. A beamsplitter directs this reflected beam of light onto an intensity detector in order to provide an output indicative of the variations in intensity. The variations in intensity are directly related to the strength of the electromagnetic radiation received by the loop antenna.

  17. Nucleon electromagnetic form factors

    SciTech Connect

    Kees de Jager

    2000-01-01

    A review of data on the nucleon electromagnetic form factors in the space-like region is presented. Recent results from experiments using polarized beams and polarized targets or nucleon recoil polarimeters have yielded a significant improvement on the precision of the data obtained with the traditional Rosenbluth separation. Future plans for extended measurements are outlined.

  18. Electromagnetic pulse bombs' defense

    NASA Astrophysics Data System (ADS)

    Chen, Bin; Wang, Yongbin; Li, Juan; Wang, Jianzhong

    2007-11-01

    With the high power microwave devices development, the high power microwave electromagnetic pulse bombs (E-bombs) have become practical abroad. The development of conventional E-bombs devices allows their use in nonnuclear confrontations. E-bombs are powerful enough to damage communication, radar, navigation and computer systems. This paper discusses effects of EMP on electrical system and how to defend the EMP.

  19. Contactless electrical conductivity measurement of electromagnetically levitated metallic melts

    SciTech Connect

    Richardsen, T.; Lohoefer, G.

    1999-07-01

    The electrical conductivity {sigma} of metallic liquids is of obvious importance to many liquid metal processing operations, because it controls the melt flow under the influence of electromagnetic fields, e.g. during casting processes, or in crystal growth furnaces. A facility for noninvasive measurements of the electrical conductivity of liquid metals above and below the melting temperature is presented. It combines the containerless positioning method of electromagnetic levitation with the contactless technique of inductive conductivity measurement. Contrary to the conventional measurement method, the sample is freely suspended within the measuring field and, thus, has no exactly predefined shape. This made a new theoretical basis necessary with implications on the measurement and levitation fields. Furthermore, the problem of the mutual inductive interactions between the levitation and the measuring coils had to be solved.

  20. Computational Electronics and Electromagnetics

    SciTech Connect

    DeFord, J.F.

    1993-03-01

    The Computational Electronics and Electromagnetics thrust area is a focal point for computer modeling activities in electronics and electromagnetics in the Electronics Engineering Department of Lawrence Livermore National Laboratory (LLNL). Traditionally, they have focused their efforts in technical areas of importance to existing and developing LLNL programs, and this continues to form the basis for much of their research. A relatively new and increasingly important emphasis for the thrust area is the formation of partnerships with industry and the application of their simulation technology and expertise to the solution of problems faced by industry. The activities of the thrust area fall into three broad categories: (1) the development of theoretical and computational models of electronic and electromagnetic phenomena, (2) the development of useful and robust software tools based on these models, and (3) the application of these tools to programmatic and industrial problems. In FY-92, they worked on projects in all of the areas outlined above. The object of their work on numerical electromagnetic algorithms continues to be the improvement of time-domain algorithms for electromagnetic simulation on unstructured conforming grids. The thrust area is also investigating various technologies for conforming-grid mesh generation to simplify the application of their advanced field solvers to design problems involving complicated geometries. They are developing a major code suite based on the three-dimensional (3-D), conforming-grid, time-domain code DSI3D. They continue to maintain and distribute the 3-D, finite-difference time-domain (FDTD) code TSAR, which is installed at several dozen university, government, and industry sites.

  1. Meaning of Interior Tomography

    PubMed Central

    Wang, Ge; Yu, Hengyong

    2013-01-01

    The classic imaging geometry for computed tomography is for collection of un-truncated projections and reconstruction of a global image, with the Fourier transform as the theoretical foundation that is intrinsically non-local. Recently, interior tomography research has led to theoretically exact relationships between localities in the projection and image spaces and practically promising reconstruction algorithms. Initially, interior tomography was developed for x-ray computed tomography. Then, it has been elevated as a general imaging principle. Finally, a novel framework known as “omni-tomography” is being developed for grand fusion of multiple imaging modalities, allowing tomographic synchrony of diversified features. PMID:23912256

  2. Magnetic induction measurements using an all-optical {sup 87}Rb atomic magnetometer

    SciTech Connect

    Wickenbrock, Arne; Tricot, François; Renzoni, Ferruccio

    2013-12-09

    In this work we propose, and experimentally demonstrate, the use of a self-oscillating all-optical atomic magnetometer for magnetic induction measurements. Given the potential for miniaturization of atomic magnetometers, and their extreme sensitivity, the present work shows that atomic magnetometers may play a key role in the development of instrumentation for magnetic induction tomography.

  3. Applicator modeling for electromagnetic thermotherapy of cervix cancer.

    PubMed

    Rezaeealam, Behrooz

    2015-03-01

    This report proposes an induction heating coil design that can be used for producing strong magnetic fields around ferromagnetic implants located in the cervix of uterus. The effect of coil design on the uniformity and extent of heat generation ability is inspected. Also, a numerical model of the applicator is developed that includes the ferromagnetic implants, and is coupled to the bioheat transfer model of the body tissue. Then, the ability of the proposed applicator for electromagnetic thermotherapy is investigated.

  4. Numerical study of magnetoacoustic signal generation with magnetic induction based on inhomogeneous conductivity anisotropy.

    PubMed

    Li, Xun; Hu, Sanqing; Li, Lihua; Zhu, Shanan

    2013-01-01

    Magnetoacoustic tomography with magnetic induction (MAT-MI) is a noninvasive imaging modality for generating electrical conductivity images of biological tissues with high spatial resolution. In this paper, we create a numerical model, including a permanent magnet, a coil, and a two-layer coaxial cylinder with anisotropic electrical conductivities, for the MAT-MI forward problem. We analyze the MAT-MI sources in two cases, on a thin conductive boundary layer and in a homogeneous medium, and then develop a feasible numerical approach to solve the MAT-MI sound source densities in the anisotropic conductive model based on finite element analysis of electromagnetic field. Using the numerical finite element method, we then investigate the magnetoacoustic effect of anisotropic conductivity under the inhomogeneous static magnetic field and inhomogeneous magnetic field, quantitatively compute the boundary source densities in the conductive model, and calculate the sound pressure. The anisotropic conductivity contributes to the distribution of the eddy current density, Lorentz force density, and acoustic signal. The proposed models and approaches provide a more realistic simulation environment for MAT-MI.

  5. Quantum tomography for measuring experimentally the matrix elements of an arbitrary quantum operation.

    PubMed

    D'Ariano, G M; Lo Presti, P

    2001-05-07

    Quantum operations describe any state change allowed in quantum mechanics, including the evolution of an open system or the state change due to a measurement. We present a general method based on quantum tomography for measuring experimentally the matrix elements of an arbitrary quantum operation. As input the method needs only a single entangled state. The feasibility of the technique for the electromagnetic field is shown, and the experimental setup is illustrated based on homodyne tomography of a twin beam.

  6. Influence of electromagnetic field intensity on the metastable zone width of CaCO3 crystallization in circulating water

    NASA Astrophysics Data System (ADS)

    Wang, Jianguo; Liang, Yandong; Chen, Si

    2016-09-01

    In this study, changes in the metastable zone width of CaCO3 crystallization was determined through conductivity titration by altering electromagnetic field parameters applied to the circulating water system. The critical conductivity value and metastable zone curves of CaCO3 crystallization were determined under different solution concentrations and electromagnetic field intensities. Experimental results indicate that the effect of the electromagnetic field intensity on the critical conductivity value intensifies with the increase of solution concentration. Moreover, the metastable zone width of CaCO3 crystallization increases with the increase of electromagnetic field intensity within 200 Gs, thereby prolonging the induction period of nucleation.

  7. Computed Tomography (CT) -- Sinuses

    MedlinePlus

    ... More Info Images/Videos About Us News Physician Resources Professions Site Index A-Z Computed Tomography (CT) - Sinuses Computed tomography (CT) of the sinuses uses special x-ray equipment to evaluate the paranasal sinus cavities – hollow, air-filled spaces within the bones of the face surrounding the ...

  8. Nasal computed tomography.

    PubMed

    Kuehn, Ned F

    2006-05-01

    Chronic nasal disease is often a challenge to diagnose. Computed tomography greatly enhances the ability to diagnose chronic nasal disease in dogs and cats. Nasal computed tomography provides detailed information regarding the extent of disease, accurate discrimination of neoplastic versus nonneoplastic diseases, and identification of areas of the nose to examine rhinoscopically and suspicious regions to target for biopsy.

  9. Inductive Reasoning and Writing

    ERIC Educational Resources Information Center

    Rooks, Clay; Boyd, Robert

    2003-01-01

    Induction, properly understood, is not merely a game, nor is it a gimmick, nor is it an artificial way of explaining an element of reasoning. Proper understanding of inductive reasoning--and the various types of reasoning that the authors term inductive--enables the student to evaluate critically other people's writing and enhances the composition…

  10. Teaching Arrangement Inductively.

    ERIC Educational Resources Information Center

    Mendelson, Michael

    1988-01-01

    Argues that teaching arrangement inductively offers an alternative to the standard imitation of business communication text models. Asserts that the inductive method stimulates individual rather than formulaic responses to the problems of organization, and that inductively-trained writers see arrangements as a powerful element in persuasive…

  11. Emergent spin electromagnetism induced by magnetization textures in the presence of spin-orbit interaction (invited)

    NASA Astrophysics Data System (ADS)

    Tatara, Gen; Nakabayashi, Noriyuki

    2014-05-01

    Emergent electromagnetic field which couples to electron's spin in ferromagnetic metals is theoretically studied. Rashba spin-orbit interaction induces spin electromagnetic field which is in the linear order in gradient of magnetization texture. The Rashba-induced effective electric and magnetic fields satisfy in the absence of spin relaxation the Maxwell's equations as in the charge-based electromagnetism. When spin relaxation is taken into account besides spin dynamics, a monopole current emerges generating spin motive force via the Faraday's induction law. The monopole is expected to play an important role in spin-charge conversion and in the integration of spintronics into electronics.

  12. Emergent spin electromagnetism induced by magnetization textures in the presence of spin-orbit interaction (invited)

    SciTech Connect

    Tatara, Gen; Nakabayashi, Noriyuki

    2014-05-07

    Emergent electromagnetic field which couples to electron's spin in ferromagnetic metals is theoretically studied. Rashba spin-orbit interaction induces spin electromagnetic field which is in the linear order in gradient of magnetization texture. The Rashba-induced effective electric and magnetic fields satisfy in the absence of spin relaxation the Maxwell's equations as in the charge-based electromagnetism. When spin relaxation is taken into account besides spin dynamics, a monopole current emerges generating spin motive force via the Faraday's induction law. The monopole is expected to play an important role in spin-charge conversion and in the integration of spintronics into electronics.

  13. ELECTROMAGNETIC RELEASE MECHANISM

    DOEpatents

    Michelson, C.

    1960-09-13

    An electromagnetic release mechanism is offered that may be used, for example, for supporting a safety rod for a nuclear reactor. The release mechanism is designed to have a large excess holding force and a rapid, uniform, and dependable release. The fast release is accomplished by providing the electromagnet with slotttd polts separated by an insulating potting resin, and by constructing the poles with a ferro-nickel alloy. The combination of these two features materially reduces the eddy current power density whenever the magnetic field changes during a release operation. In addition to these features, the design of the armature is such as to provide ready entrance of fluid into any void that might tend to form during release of the armature. This also improves the release time for the mechanism. The large holding force for the mechanism is accomplished by providing a small, selected, uniform air gap between the inner pole piece and the armature.

  14. Electromagnetic wave energy converter

    NASA Technical Reports Server (NTRS)

    Bailey, R. L. (Inventor)

    1973-01-01

    Electromagnetic wave energy is converted into electric power with an array of mutually insulated electromagnetic wave absorber elements each responsive to an electric field component of the wave as it impinges thereon. Each element includes a portion tapered in the direction of wave propagation to provide a relatively wideband response spectrum. Each element includes an output for deriving a voltage replica of the electric field variations intercepted by it. Adjacent elements are positioned relative to each other so that an electric field subsists between adjacent elements in response to the impinging wave. The electric field results in a voltage difference between adjacent elements that is fed to a rectifier to derive dc output power.

  15. DIRECT CURRENT ELECTROMAGNETIC PUMP

    DOEpatents

    Barnes, A.H.

    1957-11-01

    An improved d-c electromagnetic pump is presented in which the poles, and consequently the magetic gap at the poles, are tapered to be wider at the upstream end. In addition, the cross section of the tube carryiQ the liquid metal is tapered so that the velocity of the pumped liquid increases in the downstream direction at a rate such that the counter-induced voltage in the liquid metal remains constant as it traverses the region between the poles. This configuration compensates for the distortion of the magnetic field caused by the induced voltage that would otherwise result in the lowering of the pumping capacity. This improved electromagnetic pump as practical application in the pumping of liquid metal coolants for nuclear reactors where conventional positive displacement pumps have proved unsatisfactory due to the high temperatures and the corrosive properties of the liquid metals involved.

  16. Electromagnetic targeting of guns

    SciTech Connect

    Pogue, E.W.; Boat, R.M.; Holden, D.N.; Lopez, J.R.

    1996-10-01

    This is the final report of a one-year, Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). Electromagnetic pulse (EMP) signals produced from explosives being fired have been reported in the literature for fifty years. When a gun is fired it produces an EMP muzzle blast signal. The strength and nature of these signals was first analyzed in the early 1970s, while the results were interesting, no follow-up studies were conducted. With modern detection and signal processing technology, we believe that these signals could be used to instantaneously locate guns of virtually all calibers as they fire. The objective of our one-year project was to establish the basic nature of these signals and their utility in the concept of electromagnetic targeting of guns.

  17. Electromagnetic acoustic imaging.

    PubMed

    Emerson, Jane F; Chang, David B; McNaughton, Stuart; Jeong, Jong Seob; Shung, K K; Cerwin, Stephen A

    2013-02-01

    Electromagnetic acoustic imaging (EMAI) is a new imaging technique that uses long-wavelength RF electromagnetic (EM) waves to induce ultrasound emission. Signal intensity and image contrast have been found to depend on spatially varying electrical conductivity of the medium in addition to conventional acoustic properties. The resultant conductivity- weighted ultrasound data may enhance the diagnostic performance of medical ultrasound in cancer and cardiovascular applications because of the known changes in conductivity of malignancy and blood-filled spaces. EMAI has a potential advantage over other related imaging techniques because it combines the high resolution associated with ultrasound detection with the generation of the ultrasound signals directly related to physiologically important electrical properties of the tissues. Here, we report the theoretical development of EMAI, implementation of a dual-mode EMAI/ultrasound apparatus, and successful demonstrations of EMAI in various phantoms designed to establish feasibility of the approach for eventual medical applications.

  18. Banded electromagnetic stator core

    DOEpatents

    Fanning, Alan W.; Gonzales, Aaron A.; Patel, Mahadeo R.; Olich, Eugene E.

    1996-01-01

    A stator core for an electromagnetic pump includes a plurality of circumferentially adjoining groups of flat laminations disposed about a common centerline axis and collectively defining a central bore and a discontinuous outer perimeter, with adjacent groups diverging radially outwardly to form V-shaped gaps. An annular band surrounds the groups and is predeterminedly tensioned to clamp together the laminations, and has a predetermined flexibility in a radial direction to form substantially straight bridge sections between the adjacent groups.

  19. Banded electromagnetic stator core

    DOEpatents

    Fanning, A.W.; Gonzales, A.A.; Patel, M.R.; Olich, E.E.

    1994-04-05

    A stator core for an electromagnetic pump includes a plurality of circumferentially adjoining groups of flat laminations disposed about a common centerline axis and collectively defining a central bore and a discontinuous outer perimeter, with adjacent groups diverging radially outwardly to form V-shaped gaps. An annular band surrounds the groups and is predeterminedly tensioned to clamp together the laminations, and has a predetermined flexibility in a radial direction to form substantially straight bridge sections between the adjacent groups. 5 figures.

  20. Banded electromagnetic stator core

    DOEpatents

    Fanning, Alan W.; Gonzales, Aaron A.; Patel, Mahadeo R.; Olich, Eugene E.

    1994-01-01

    A stator core for an electromagnetic pump includes a plurality of circumferentially adjoining groups of flat laminations disposed about a common centerline axis and collectively defining a central bore and a discontinuous outer perimeter, with adjacent groups diverging radially outwardly to form V-shaped gaps. An annular band surrounds the groups and is predeterminedly tensioned to clamp together the laminations, and has a predetermined flexibility in a radial direction to form substantially straight bridge sections between the adjacent groups.

  1. Banded electromagnetic stator core

    DOEpatents

    Fanning, A.W.; Gonzales, A.A.; Patel, M.R.; Olich, E.E.

    1996-06-11

    A stator core for an electromagnetic pump includes a plurality of circumferentially adjoining groups of flat laminations disposed about a common centerline axis and collectively defining a central bore and a discontinuous outer perimeter, with adjacent groups diverging radially outwardly to form V-shaped gaps. An annular band surrounds the groups and is predeterminedly tensioned to clamp together the laminations, and has a predetermined flexibility in a radial direction to form substantially straight bridge sections between the adjacent groups. 5 figs.

  2. Proca and electromagnetic fields

    SciTech Connect

    Hillion, P.; Quinnerz, S.

    1986-07-01

    In the framework of the proper orthochronous Lorentz group, the old connection is revived between the electromagnetic field characterized by a self-dual tensor and a traceless second-rank spinor obeying the Proca equation. The relationship between this spinor and the Hertz potential also considered as a self-dual tensor is emphasized. The extension of this formalism to meet the covariance under the full Lorentz group is also discussed.

  3. Electromagnetic Hammer for Metalworking

    NASA Technical Reports Server (NTRS)

    Anderson, S. A.; Brunet, F.; Dowd, A.; Durham, R.; Ezell, J.; Gorr, G.; Hartley, D.; Jackson, F.; Marchand, J.; Macfarlane, W.; Nameth, P.; Okelly, K.; Phillips, H.; Rollo, J.; Rupert, E.; Sykes, H.; Vitrano, E.; Woods, M.

    1986-01-01

    High eddy currents apply pressure for cold-forming. Coil housing constructed for mechanical strength to hold coil against magnetic force, to maintain electrical contact with coil ends, and to maintain insulation between coil turns. Drilled holes placed to facilitate release of bubbles during potting. In contrast with mechanical hammers, electromagnetic hammer requires no dynamic material contact with workpiece; consequently, produces almost no change in metal grain structure.

  4. Modern Electromagnetic Scattering

    DTIC Science & Technology

    2013-08-10

    multiple thin coatings, J. Opt. Soc. Am. 37 (1947) 576–577. [11] F. Abelès, La théorie générale des couches minces, J. Phys. Radium 11 (1950) 307...Abelès, La théorie générale des couches minces, J. Phys. Radium 11 (1950) 307–310. [11] M. Born, E. Wolf, Principles of Optics: Electromagnetic Theory

  5. Ordinary electromagnetic mode instability

    NASA Technical Reports Server (NTRS)

    Cheng, C. Z.

    1974-01-01

    The instability of the ordinary electromagnetic mode propagating perpendicular to an external magnetic field is studied for a single-species plasma with ring velocity distribution. The marginal instability boundaries for both the purely growing mode and the propagating growing modes are calculated from the instability criteria. The dispersion characteristics for various sets of plasma parameters are also given. The typical growth rates are of the order of the cyclotron frequency.

  6. Effects of pulsed electromagnetic field frequencies on the osteogenic differentiation of human mesenchymal stem cells.

    PubMed

    Luo, Fei; Hou, Tianyong; Zhang, Zehua; Xie, Zhao; Wu, Xuehui; Xu, Jianzhong

    2012-04-01

    The purpose of this study was to evaluate the effect of different frequencies of pulsed electromagnetic fields on the osteogenic differentiation of human mesenchymal stem cells. Third-generation human mesenchymal stem cells were irradiated with different frequencies of pulsed electromagnetic fields, including 5, 25, 50, 75, 100, and 150 Hz, with a field intensity of 1.1 mT, for 30 minutes per day for 21 days. Changes in human mesenchymal stem cell morphology were observed using phase contrast microscopy. Alkaline phosphatase activity and osteocalcin expression were also determined to evaluate human mesenchymal stem cell osteogenic differentiation.Different effects were observed on human mesenchymal stem cell osteoblast induction following exposure to different pulsed electromagnetic field frequencies. Levels of human mesenchymal stem cell differentiation increased when the pulsed electromagnetic field frequency was increased from 5 hz to 50 hz, but the effect was weaker when the pulsed electromagnetic field frequency was increased from 50 Hz to 150 hz. The most significant effect on human mesenchymal stem cell differentiation was observed at of 50 hz.The results of the current study show that pulsed electromagnetic field frequency is an important factor with regard to the induction of human mesenchymal stem cell differentiation. Furthermore, a pulsed electromagnetic field frequency of 50 Hz was the most effective at inducing human mesenchymal stem cell osteoblast differentiation in vitro.

  7. Carter separable electromagnetic fields

    NASA Astrophysics Data System (ADS)

    Lynden-Bell, D.

    2000-02-01

    The purely electromagnetic analogue in flat space of Kerr's metric in general relativity is only rarely considered. Here we carry out in flat space a programme similar to Carter's investigation of metrics in general relativity in which the motion of a charged particle is separable. We concentrate on the separability of the motion (be it classical, relativistic or quantum) of a charged particle in electromagnetic fields that lie in planes through an axis of symmetry. In cylindrical polar coordinates (t,R,φ,z) the four-vector potential takes the form [formmu2] is the unit toroidal vector. The forms of the functions Φ(R,z) and A(R,z) are sought that allow separable motion. This occurs for relativistic motion only when AR,Φ and A2-Φ2 are all of the separable form ζ(λ)-η(μ)]/(λ-μ), where ζ and η are arbitrary functions, and λ and μ are spheroidal coordinates or degenerations thereof. The special forms of A and Φ that allow this are deduced. They include the Kerr metric analogue, with E+iB=-∇{q[(r-ia).(r-ia)]-1/2}. Rather more general electromagnetic fields allow separation when the motion is non-relativistic. The investigation is extended to fields that lie in parallel planes. Connections to Larmor's theorem are remarked upon.

  8. Electromagnetic flat sheet forming by spiral type actuator coil

    NASA Astrophysics Data System (ADS)

    Akbar, S.; Aleem, M. A.; Sarwar, M. N.; Zillohu, A. U.; Awan, M. S.; Haider, A.; Ahmad, Z.; Akhtar, S.; Farooque, M.

    2016-08-01

    Focus of present work is to develop a setup for high strain rate electromagnetic forming of thin aluminum sheets (0.5, 1.0, 1.5 and 2.0 mm) and optimization of forming parameters. Flat spiral coil of 99.9% pure Cu strip (2.5x8.0 mm) with self-inductance 11 μH, 13 no. of turns and resultant outer diameter of 130mm has been fabricated and was coupled to a capacitor bank of energy, voltage and capacitance of 9 kJ, 900 V and 22.8 mF, respectively. To optimize the coil design, a commercially available software FEMM-4.2 was used to simulate the electromagnetic field profile generated by the coils of different pitch but same number of turns. Results of electromagnetic field intensity proposed by simulation agree in close proximity with those of theoretical as well as experimental data. The calculation of electromagnetic force and magnetic couplings between the coil and metal sheet are made. Forming parameters were optimized for different sheet thicknesses. Electromagnetic field intensity's profile plays a principal role in forming of typical shapes and patterns in sheets.

  9. Coherent hybrid electromagnetic field imaging

    DOEpatents

    Cooke, Bradly J.; Guenther, David C.

    2008-08-26

    An apparatus and corresponding method for coherent hybrid electromagnetic field imaging of a target, where an energy source is used to generate a propagating electromagnetic beam, an electromagnetic beam splitting means to split the beam into two or more coherently matched beams of about equal amplitude, and where the spatial and temporal self-coherence between each two or more coherently matched beams is preserved. Two or more differential modulation means are employed to modulate each two or more coherently matched beams with a time-varying polarization, frequency, phase, and amplitude signal. An electromagnetic beam combining means is used to coherently combine said two or more coherently matched beams into a coherent electromagnetic beam. One or more electromagnetic beam controlling means are used for collimating, guiding, or focusing the coherent electromagnetic beam. One or more apertures are used for transmitting and receiving the coherent electromagnetic beam to and from the target. A receiver is used that is capable of square-law detection of the coherent electromagnetic beam. A waveform generator is used that is capable of generation and control of time-varying polarization, frequency, phase, or amplitude modulation waveforms and sequences. A means of synchronizing time varying waveform is used between the energy source and the receiver. Finally, a means of displaying the images created by the interaction of the coherent electromagnetic beam with target is employed.

  10. Unique Computer Modeling Approaches for Simulation of Induction Heating and Heat-Treating Processes

    NASA Astrophysics Data System (ADS)

    Rudnev, Valery

    2013-07-01

    In the last decade, when discussing subjects related to a computer modeling of induction heating and heat treating, the word "usefulness" has been replaced by the word "necessity." Modern computer simulation is capable of effectively simulating electromagnetic and thermal phenomena for many processes, including those that involve electromagnetic induction. This article discusses the state-of-the-art computer simulation of induction heating and heat treating providing answers to following questions: Why finite element analysis is not always the best tool for computer modeling of some induction heating applications? What are the limitations of generalized all-purpose commercial programs? What are the crucial tips that executives must know regarding computer modeling of induction heating? Several case studies will be reviewed in this article as well.

  11. Field implementation of geophysical diffraction tomography

    SciTech Connect

    Witten, A.J.; Stevens, S.S.

    1984-01-01

    Geophysical diffraction tomography is a new technique that shows promise as a tool for quantitative subsurface (below-ground) imaging. The approach being used is based upon the filtered backpropagation algorithm, which is a mathematical extension of the reconstruction software used in conventional X-ray CAT scanners. The difference between this method and existing methods is that the new algorithm rigorously accounts for diffraction effects through an exact inversion of the wave equation. This refinement is necessary in that it admits the use of acoustic and long-wavelength electromagnetic waves, allowing tomography to be taken from the laboratory to the field. ORNL's effort in geophysical diffraction tomography involves reducing the filtered backpropagation algorithm to practice. This requires the design and construction of field instrumentation as well as the development of an improved algorithm. The original algorithm requires the imaged region to be illuminated by plane waves. This requirement simplifies the algorithm but complicates its field implementation in that plane waves are difficult to generate. Consequently, ORNL has been working to generalize the filtered backpropagation algorithm to allow a broader range of incoming wave fields which can more easily be realized in the field. The instrumentation aspects involve the selection of appropriate sonic sources and receivers along with the development of a state-of-art, portable, computer-controlled, multichannel data acquisition system. 5 references, 6 figures.

  12. Reverse engineering of inductive fault current limiters

    NASA Astrophysics Data System (ADS)

    Pina, J. M.; Suárez, P.; Ventim Neves, M.; Álvarez, A.; Rodrigues, A. L.

    2010-06-01

    The inductive fault current limiter is less compact and harder to scale to high voltage networks than the resistive one. Nevertheless, its simple construction and mechanical robustness make it attractive in low voltage grids. Thus, it might be an enabling technology for the advent of microgrids, low voltage networks with dispersed generation, controllable loads and energy storage. A new methodology for reverse engineering of inductive fault current limiters based on the independent analysis of iron cores and HTS cylinders is presented in this paper. Their electromagnetic characteristics are used to predict the devices' hysteresis loops and consequently their dynamic behavior. Previous models based on the separate analysis of the limiters' components were already derived, e.g. in transformer like equivalent models. Nevertheless, the assumptions usually made may limit these models' application, as shown in the paper. The proposed methodology obviates these limitations. Results are validated through simulations.

  13. Pulsed IR inductive lasers

    NASA Astrophysics Data System (ADS)

    Razhev, A. M.; Churkin, D. S.; Kargapol'tsev, E. S.

    2014-07-01

    Pulsed inductive discharge is a new alternative method of pumping active gas laser media. The work presents results of experimental investigations of near, mid, and far IR inductive gas lasers (H2, HF, and CO2) operating at different transitions of atoms and molecules with different mechanisms of formation of inversion population. The excitation systems of a pulsed inductive cylindrical discharge (pulsed inductively coupled plasma) and pulsed RF inductive discharge in the gases are developed. Various gas mixtures including H2, N2, He, Ne, F2, NF3, and SF6 are used. Characteristics of near IR H2 laser radiation are investigated. Maximal pulse peak power of 7 kW is achieved. The possibility of using a pulsed inductive discharge as a new method of pumping HF laser active medium is demonstrated. The pulsed RF inductive CO2 laser is created and a total efficiency of 17% is achieved.

  14. An electromagnetic modulator based on electrically controllable metamaterial analogue to electromagnetically induced transparency

    NASA Astrophysics Data System (ADS)

    Fan, Yuancheng; Qiao, Tong; Zhang, Fuli; Fu, Quanhong; Dong, Jiajia; Kong, Botao; Li, Hongqiang

    2017-01-01

    Electromagnetically induced transparency (EIT) is a promising technology for the enhancement of light-matter interactions, and recent demonstrations of the EIT analogue realized in artificial micro-structured medium have remarkably reduced the extreme requirement for experimental observation of EIT spectrum. In this paper, we propose to electrically control the EIT-like spectrum in a metamaterial as an electromagnetic modulator. A diode acting as a tunable resistor is loaded in the gap of paired wires to inductively tune the magnetic resonance, which induces remarkable modulation on the EIT-like spectrum through the metamaterial sample. The experimental measurements confirmed that the prediction of electromagnetic modulation in three narrow bands on the EIT-like spectrum, and a modulation contrast of up to 31 dB was achieved on the transmission through the metamaterial. Our results may facilitate the study on active/dynamical technology in translational metamaterials, which connect extraordinary manipulations on the flow of light in metamaterials, e.g., the exotic EIT, and practical applications in industry.

  15. An electromagnetic modulator based on electrically controllable metamaterial analogue to electromagnetically induced transparency

    PubMed Central

    Fan, Yuancheng; Qiao, Tong; Zhang, Fuli; Fu, Quanhong; Dong, Jiajia; Kong, Botao; Li, Hongqiang

    2017-01-01

    Electromagnetically induced transparency (EIT) is a promising technology for the enhancement of light-matter interactions, and recent demonstrations of the EIT analogue realized in artificial micro-structured medium have remarkably reduced the extreme requirement for experimental observation of EIT spectrum. In this paper, we propose to electrically control the EIT-like spectrum in a metamaterial as an electromagnetic modulator. A diode acting as a tunable resistor is loaded in the gap of paired wires to inductively tune the magnetic resonance, which induces remarkable modulation on the EIT-like spectrum through the metamaterial sample. The experimental measurements confirmed that the prediction of electromagnetic modulation in three narrow bands on the EIT-like spectrum, and a modulation contrast of up to 31 dB was achieved on the transmission through the metamaterial. Our results may facilitate the study on active/dynamical technology in translational metamaterials, which connect extraordinary manipulations on the flow of light in metamaterials, e.g., the exotic EIT, and practical applications in industry. PMID:28091539

  16. An electromagnetic modulator based on electrically controllable metamaterial analogue to electromagnetically induced transparency.

    PubMed

    Fan, Yuancheng; Qiao, Tong; Zhang, Fuli; Fu, Quanhong; Dong, Jiajia; Kong, Botao; Li, Hongqiang

    2017-01-16

    Electromagnetically induced transparency (EIT) is a promising technology for the enhancement of light-matter interactions, and recent demonstrations of the EIT analogue realized in artificial micro-structured medium have remarkably reduced the extreme requirement for experimental observation of EIT spectrum. In this paper, we propose to electrically control the EIT-like spectrum in a metamaterial as an electromagnetic modulator. A diode acting as a tunable resistor is loaded in the gap of paired wires to inductively tune the magnetic resonance, which induces remarkable modulation on the EIT-like spectrum through the metamaterial sample. The experimental measurements confirmed that the prediction of electromagnetic modulation in three narrow bands on the EIT-like spectrum, and a modulation contrast of up to 31 dB was achieved on the transmission through the metamaterial. Our results may facilitate the study on active/dynamical technology in translational metamaterials, which connect extraordinary manipulations on the flow of light in metamaterials, e.g., the exotic EIT, and practical applications in industry.

  17. Constraining electromagnetic core-mantle coupling

    NASA Astrophysics Data System (ADS)

    Wicht, J.; Jault, D.

    1999-02-01

    Electromagnetic core-mantle coupling is one candidate for explaining length of day (LOD) variations on decadal time scales. This coupling has traditionally been calculated from models of core surface flow /U-->, but core flow inversions are not unique. Unfortunately, the main torque contribution depends on the toroidal part /∇×r-->Φ of the vector field (U-->Br), which is left undetermined by the radial induction equation that links core flows to magnetic field data under the frozen-flux hypothesis. (Br is the radial magnetic field at the core surface.) We have developed a new method that bypasses flow inversions. Using the vector field (U-->Br) directly, we estimate its toroidal part by imposing that (U-->Br) vanishes where Br=0. The calculation of the electromagnetic torque is also hindered by the uncertainty in the conductivity structure of the lower mantle. However, we conclude that the conductivity of the lower mantle has to be much larger than current estimates derived from diamond anvil cell experiments to make the electromagnetic torque significant. The region beneath Africa and the mid-Atlantic (where there is the most significant (Br=0) curve apart from the magnetic equator) is particularly important. Here, the field Φ is relatively well constrained, and this is the single region that contributes most to the torque. Following Holme [Holme, R., 1998a. Electromagnetic core-mantle coupling 1: explaining decadal changes in the length of day. Geophys. J. Int. (132) 167-180.], we show nevertheless that small changes to Φ suffice to recover the torque ΓLOD required to explain LOD variations provided that the lower mantle conductivity is high enough. We find a value similar to Holme [Holme, R., 1998b. Electromagnetic core-mantle coupling 2: probing deep mantle conductance. In: Gunis, M., Wysession, M.E., Knittel, E., Buffett, B.A. (Eds.), The Core-Mantle Boundary Region. AGU, pp. 139-151.] for the minimum conductance (108 S). However, we were not able to

  18. Fusion Research of Electrical Tomography with Other Sensors for Two-phase Flow Measurement

    NASA Astrophysics Data System (ADS)

    Deng, Xiang; Yang, W. Q.

    2012-01-01

    The two-phase flow widely exists in the nature and industrial processes. The measurement of two-phase flows, including gas/solids, gas/liquid and liquid/liquid flows, is still challenging. Fusions of electrical tomography with conventional sensors provide possibilities to improve two-phase flow accurate measurement. In this paper, fusions of (1) electrical resistance tomography (ERT) with electromagnetic (EM) flowmeter, (2) electrical capacitance tomography (ECT) with ERT and (3) ECT with electrostatic sensor are introduced. Some research results of fusion methods are presented and discussed. This paper can provide the theoretical support for the multi-sensor fusion for two-phase flow measurement.

  19. Electromagnetic Meissner-Effect Launcher

    NASA Technical Reports Server (NTRS)

    Robertson, Glen A.

    1990-01-01

    Proposed electromagnetic Meissner-effect launching apparatus differs from previous electromagnetic launchers; no need for electromagnet coil on projectile. Result, no need for brush contacts and high-voltage commutation equipment to supply current directly to projectile coil, or for pulse circuitry to induce current in projectile coil if brush contacts not used. Compresses magnetic field surrounding rear surface of projectile, creating gradient of magnetic pressure pushing projectile forward.

  20. Stress and Distortion Evolution During Induction Case Hardening of Tube

    NASA Astrophysics Data System (ADS)

    Nemkov, Valentin; Goldstein, Robert; Jackowski, John; Ferguson, Lynn; Li, Zhichao

    2013-07-01

    Simulation of stresses during heat treatment relates usually to furnace heating. Induction heating provides a very different evolution of temperature in the part and therefore different stresses. This may be positive for service properties or negative, reducing component strength or even causing cracks. A method of coupled simulation between electromagnetic, thermal, structural, stress, and deformation phenomena during induction tube hardening is described. Commercial software package ELTA is used to calculate the power density distribution in the load resulting from the induction heating process. The program DANTE is used to predict temperature distribution, phase transformations, stress state, and deformation during heating and quenching. Analyses of stress and deformation evolution were made on a simple case of induction hardening of external (1st case) and internal (2nd case) surfaces of a thick-walled tubular body.

  1. Electromagnetic Meissner effect launcher

    NASA Technical Reports Server (NTRS)

    Robertson, Glen A. (Inventor)

    1991-01-01

    An electromagnetic projectile launcher provides acceleration of a superconducting projectile through the diamagnetic repulsion of the superconducting projectile. A superconducting layer is provided aft of the projectile, either directly on the projectile or on a platform upon which the projectile is carried, and a traveling magnetic field is caused to propagate along a magnetic field drive coil in which the projectile is disposed. The resulting diamagnetic repulsion between the superconducting projectile and the traveling magnetic field causes the projectile to be propelled along the coil. In one embodiment, a segmented drive coil is used to generate the traveling magnetic field.

  2. Electromagnetic strong plasma turbulence

    SciTech Connect

    Melatos, A.; Jenet, F. A.; Robinson, P. A.

    2007-02-15

    The first large-scale simulations of continuously driven, two-dimensional electromagnetic strong plasma turbulence are performed, for electron thermal speeds 0.01c{<=}v{<=}0.57c, by integrating the Zakharov equations for coupled Langmuir and transverse (T) waves near the plasma frequency. Turbulence scalings and wave number spectra are calculated, a transition is found from a mix of trapped and free T eigenstates for v{>=}0.1c to just free eigenstates for v{<=}0.1c, and wave energy densities are observed to undergo slow quasiperiodic oscillations.

  3. Electromagnetic pump stator coil

    DOEpatents

    Fanning, Alan W.; Dahl, Leslie R.

    1996-01-01

    An electrical stator coil for an electromagnetic pump includes a continuous conductor strip having first and second terminals at opposite ends thereof and an intermediate section disposed therebetween. The strip is configured in first and second coil halves, with the first coil half including a plurality of windings extending from the first terminal to the intermediate section, and the second coil half including a plurality of windings extending from the second terminal to the intermediate section. The first and second coil halves are disposed coaxially, and the first and second terminals are disposed radially inwardly therefrom with the intermediate section being disposed radially outwardly therefrom.

  4. Electromagnetic pump stator coil

    DOEpatents

    Fanning, A.W.; Dahl, L.R.

    1996-06-25

    An electrical stator coil for an electromagnetic pump includes a continuous conductor strip having first and second terminals at opposite ends thereof and an intermediate section disposed therebetween. The strip is configured in first and second coil halves, with the first coil half including a plurality of windings extending from the first terminal to the intermediate section, and the second coil half including a plurality of windings extending from the second terminal to the intermediate section. The first and second coil halves are disposed coaxially, and the first and second terminals are disposed radially inwardly therefrom with the intermediate section being disposed radially outwardly therefrom. 9 figs.

  5. Electromagnetic levitation applications

    SciTech Connect

    Bayazitoglu, Y.

    1996-11-01

    At high temperatures, most materials react with the walls of their containers. This inevitably leads to material contamination and property degradation. Therefore, it becomes difficult to process materials to the required degree of purity and/or measure their properties at high temperatures. Levitation melting has been used on earth and microgravity since to circumvent this problem. In this paper, first a broad survey of the work done in electromagnetic levitation since its invention is given. Then the heat generation due to an alternating magnetic field is studied. Finally, the application of levitation melting in the determination of thermal diffusivity, emissivity, surface tension and viscosity of liquid metals is presented.

  6. Advanced electromagnetic gun simulation

    NASA Astrophysics Data System (ADS)

    Brown, J. L.; George, E. B.; Lippert, J. R.; Balius, A. R.

    1986-11-01

    The architecture, software and application of a simulation system for evaluating electromagnetic gun (EMG) operability, maintainability, test data and performance tradeoffs are described. The system features a generic preprocessor designed for handling the large data rates necessary for EMG simulations. The preprocessor and postprocessor operate independent of the EMG simulation, which is viewed through windows by the user, who can then select the areas of the simulation desired. The simulation considers a homopolar generator, busbars, pulse shaping coils, the barrel, switches, and prime movers. In particular, account is taken of barrel loading by the magnetic field, Lorentz force and plasma pressure.

  7. Optical coherence tomography findings of bilateral foveal leukemic infiltration

    PubMed Central

    Le, John Q; Braich, Puneet S; Brar, Vikram S

    2016-01-01

    We report a case of a 59-year-old man with a history of atypical chronic myelogenous leukemia who presented with a several-week history of decreased vision in both eyes. His clinical examination revealed bilateral foveal infiltration, which was also demonstrated on optical coherence tomography. After a failed induction with imatinib (Gleevec®), he was treated with omacetaxine (Synribo®) with an appropriate hematologic response. As his leukemia improved with chemotherapy, his retinal lesions regressed as demonstrated by serial optical coherence tomography and fundus photographs, with near complete restoration of foveal architecture. PMID:27540313

  8. Sequential inductive learning

    SciTech Connect

    Gratch, J.

    1996-12-31

    This article advocates a new model for inductive learning. Called sequential induction, it helps bridge classical fixed-sample learning techniques (which are efficient but difficult to formally characterize), and worst-case approaches (which provide strong statistical guarantees but are too inefficient for practical use). Learning proceeds as a sequence of decisions which are informed by training data. By analyzing induction at the level of these decisions, and by utilizing the only enough data to make each decision, sequential induction provides statistical guarantees but with substantially less data than worst-case methods require. The sequential inductive model is also useful as a method for determining a sufficient sample size for inductive learning and as such, is relevant to learning problems where the preponderance of data or the cost of gathering data precludes the use of traditional methods.

  9. Computerised Axial Tomography (CAT)

    DTIC Science & Technology

    1990-06-01

    OF COMPUTERISED AXIAL TOMOGRAPHY Paragraph 1.1 ORIGIN, DEVELOPMENT AND MARKET OF CAT Paragraph 1.2 EQUIPMENT Chapter 2 OPERATIONAL PRINCIPLE OF A CT...DEVELOPMENT OF THE COMPUTERISED AXIAL TOMOGRAPHY 1.1 Origin, development and marketing of the CAT The origin of the CAT goes back to 1961 when...count on wide commercial possibilities, in the international market . In particular, EMI entered, very forcefully, the American market , always

  10. STRUCTURAL RESPONSE TO INTENSE ELECTROMAGNETIC RADIATION.

    DTIC Science & Technology

    EXPLODING WIRES, *GLASS, *DAMAGE, ELECTROMAGNETIC RADIATION , ENERGY CONVERSION, ENERGY CONVERSION, ELECTROMAGNETIC RADIATION , ELECTROMAGNETIC ... RADIATION , PLASTICS, PLASMAS(PHYSICS), STRESSES, THERMAL STRESSES, INSTRUMENTATION, ELECTRICAL RESISTANCE, ELECTRIC DISCHARGES, THERMOCOUPLES, MATHEMATICAL ANALYSIS, MATHEMATICAL ANALYSIS.

  11. The gravitational analog of Faraday's induction law

    NASA Astrophysics Data System (ADS)

    Zile, Daniel; Overduin, James

    2015-04-01

    Michael Faraday, the discoverer of electromagnetic induction, was convinced that there must also be a gravitational analog of this law, and he carried out drop-tower experiments in 1849 to look for the electric current induced in a coil by changes in gravitational flux through the coil. This work, now little remembered, was in some ways the first investigation of what we would now call a unified-field theory. We revisit Faraday's experiments in the light of current knowledge and ask what might be learned if they were to be performed today. We then review the gravitational analog for Faraday's law that arises within the vector (or gravito-electromagnetic) approximation to Einstein's theory of general relativity in the weak-field, low-velocity limit. This law relates spinning masses and induced ``mass currents'' rather than spinning charges and electric currents, but is otherwise remarkably similar to its electromagnetic counterpart. The predicted effects are completely unobservable in everyday settings like those envisioned by Faraday, but are thought to be relevant in astrophysical contexts like the accretion disks around collapsed stars, thus bearing out Faraday's remarkable intuition. Undergraduate student.

  12. Numerical simulation of inclination vibration in magnetic induction micromachines

    NASA Astrophysics Data System (ADS)

    Chen, J.-Y.; Zhou, J.-B.; Zhang, W.-M.; Meng, G.

    2008-02-01

    This paper studies the inclination vibration of an axial-flux magnetic induction micromachine which is supported by hydrostatic thrust bearings. A mechanical model for the rotor and the corresponding fluid-film bearing is combined with an electromagnetic force model to study the linear and nonlinear rotordynamics of the system. Results obtained for the stability show that magnetic induction micromachine would encounter severe instability problem at high speed operations. The model developed here could serve as a useful reference for design optimization and operation scheme.

  13. Metamaterials beyond electromagnetism.

    PubMed

    Kadic, Muamer; Bückmann, Tiemo; Schittny, Robert; Wegener, Martin

    2013-12-01

    Metamaterials are rationally designed man-made structures composed of functional building blocks that are densely packed into an effective (crystalline) material. While metamaterials are mostly associated with negative refractive indices and invisibility cloaking in electromagnetism or optics, the deceptively simple metamaterial concept also applies to rather different areas such as thermodynamics, classical mechanics (including elastostatics, acoustics, fluid dynamics and elastodynamics), and, in principle, also to quantum mechanics. We review the basic concepts, analogies and differences to electromagnetism, and give an overview on the current state of the art regarding theory and experiment-all from the viewpoint of an experimentalist. This review includes homogeneous metamaterials as well as intentionally inhomogeneous metamaterial architectures designed by coordinate-transformation-based approaches analogous to transformation optics. Examples are laminates, transient thermal cloaks, thermal concentrators and inverters, 'space-coiling' metamaterials, anisotropic acoustic metamaterials, acoustic free-space and carpet cloaks, cloaks for gravitational surface waves, auxetic mechanical metamaterials, pentamode metamaterials ('meta-liquids'), mechanical metamaterials with negative dynamic mass density, negative dynamic bulk modulus, or negative phase velocity, seismic metamaterials, cloaks for flexural waves in thin plates and three-dimensional elastostatic cloaks.

  14. Electromagnetic Field Penetration Studies

    NASA Technical Reports Server (NTRS)

    Deshpande, M.D.

    2000-01-01

    A numerical method is presented to determine electromagnetic shielding effectiveness of rectangular enclosure with apertures on its wall used for input and output connections, control panels, visual-access windows, ventilation panels, etc. Expressing EM fields in terms of cavity Green's function inside the enclosure and the free space Green's function outside the enclosure, integral equations with aperture tangential electric fields as unknown variables are obtained by enforcing the continuity of tangential electric and magnetic fields across the apertures. Using the Method of Moments, the integral equations are solved for unknown aperture fields. From these aperture fields, the EM field inside a rectangular enclosure due to external electromagnetic sources are determined. Numerical results on electric field shielding of a rectangular cavity with a thin rectangular slot obtained using the present method are compared with the results obtained using simple transmission line technique for code validation. The present technique is applied to determine field penetration inside a Boeing-757 by approximating its passenger cabin as a rectangular cavity filled with a homogeneous medium and its passenger windows by rectangular apertures. Preliminary results for, two windows, one on each side of fuselage were considered. Numerical results for Boeing-757 at frequencies 26 MHz, 171-175 MHz, and 428-432 MHz are presented.

  15. Metamaterials beyond electromagnetism

    NASA Astrophysics Data System (ADS)

    Kadic, Muamer; Bückmann, Tiemo; Schittny, Robert; Wegener, Martin

    2013-12-01

    Metamaterials are rationally designed man-made structures composed of functional building blocks that are densely packed into an effective (crystalline) material. While metamaterials are mostly associated with negative refractive indices and invisibility cloaking in electromagnetism or optics, the deceptively simple metamaterial concept also applies to rather different areas such as thermodynamics, classical mechanics (including elastostatics, acoustics, fluid dynamics and elastodynamics), and, in principle, also to quantum mechanics. We review the basic concepts, analogies and differences to electromagnetism, and give an overview on the current state of the art regarding theory and experiment—all from the viewpoint of an experimentalist. This review includes homogeneous metamaterials as well as intentionally inhomogeneous metamaterial architectures designed by coordinate-transformation-based approaches analogous to transformation optics. Examples are laminates, transient thermal cloaks, thermal concentrators and inverters, ‘space-coiling’ metamaterials, anisotropic acoustic metamaterials, acoustic free-space and carpet cloaks, cloaks for gravitational surface waves, auxetic mechanical metamaterials, pentamode metamaterials (‘meta-liquids’), mechanical metamaterials with negative dynamic mass density, negative dynamic bulk modulus, or negative phase velocity, seismic metamaterials, cloaks for flexural waves in thin plates and three-dimensional elastostatic cloaks.

  16. Electro-magnetic compatibility

    NASA Astrophysics Data System (ADS)

    Maidment, H.

    1980-05-01

    The historical background to the growth in problems of electromagnetic compatibility (EMC) in UK Military aircraft is reviewed and the present approach for minimizing these problems during development is discussed. The importance of using representative aircraft for final EMC assessments is stressed, and the methods of approach in planning and executing such tests are also outlined. The present equipment qualification procedures are based on assumptions regarding the electromagnetic fields present within the airframe, and the nature of the coupling mechanisms. These cannot be measured with any certainty in representative aircraft. Thus EMC assessments rely on practical tests. Avionics systems critical to flight safety, and systems vital to mission effectiveness require test methods that provide a measure of the safety and performance margins available to account for variations that occur in production and service use. Some proven methods are available, notably for detonator circuits, but in most other areas further work is required. Encouraging process has been made in the use of current probes for the measurement of interfering signals on critical signal lines, in conjunction with complementary test house procedures, as a means for obtaining the safety margins required in flight and engine control systems. Performance margins for mission systems using digital techniques are difficult to determine, and there is a need for improved test techniques. The present EMC qualification tests for equipment in the laboratory do not guarantee freedom from interference when installed, and the results are limited in value for correlating with aircraft tests.

  17. The HPS electromagnetic calorimeter

    DOE PAGES

    Balossino, I.; Baltzell, N.; Battaglieri, M.; ...

    2017-02-22

    The Heavy Photon Search experiment (HPS) is searching for a new gauge boson, the so-called "heavy photon". Through its kinetic mixing with the Standard Model photon, this particle could decay into an electron-positron pair. It would then be detectable as a narrow peak in the invariant mass spectrum of such pairs, or, depending on its lifetime, by a decay downstream of the production target. The HPS experiment is installed in Hall-B of Jefferson Lab. This article presents the design and performance of one of the two detectors of the experiment, the electromagnetic calorimeter, during the runs performed in 2015-2016. The calorimeter's main purpose is to provide a fast trigger and reduce the copious background from electromagnetic processes through matching with a tracking detector. Finally, the detector is a homogeneous calorimeter, made of 442 lead-tungsten (PbWOmore » $$_4$$) scintillating crystals, each read-out by an avalanche photodiode coupled to a custom trans-impedance amplifier.« less

  18. Knots in electromagnetism

    NASA Astrophysics Data System (ADS)

    Arrayás, M.; Bouwmeester, D.; Trueba, J. L.

    2017-01-01

    Maxwell equations in vacuum allow for solutions with a non-trivial topology in the electric and magnetic field line configurations at any given moment in time. One example is a space filling congruence of electric and magnetic field lines forming circles lying on the surfaces of nested tori. In this example the electric, magnetic and Poynting vector fields are orthogonal everywhere. As time evolves the electric and magnetic fields expand and deform without changing the topology and energy, while the Poynting vector structure remains unchanged while propagating with the speed of light. The topology is characterized by the concept of helicity of the field configuration. Helicity is an important fundamental concept and for massless fields it is a conserved quantity under conformal transformations. We will review several methods by which linked and knotted electromagnetic (spin-1) fields can be derived. A first method, introduced by A. Rañada, uses the formulation of the Maxwell equations in terms of differential forms combined with the Hopf map from the three-sphere S3 to the two-sphere S2. A second method is based on spinor and twistor theory developed by R. Penrose in which elementary twistor functions correspond to the family of electromagnetic torus knots. A third method uses the Bateman construction of generating null solutions from complex Euler potentials. And a fourth method uses special conformal transformations, in particular conformal inversion, to generate new linked and knotted field configurations from existing ones. This fourth method is often accompanied by shifting singularities in the field to complex space-time points. Of course the various methods must be closely related to one another although they have been developed largely independently and they suggest different directions in which to expand the study of topologically non-trivial field configurations. It will be shown how the twistor formulation allows for a direct extension to massless

  19. Induction heating apparatus and methods of operation thereof

    SciTech Connect

    Richardson, John G.

    2006-08-01

    Methods of operation of an induction melter include providing material within a cooled crucible proximate an inductor. A desired electromagnetic flux skin depth for heating the material within the crucible may be selected, and a frequency of an alternating current for energizing the inductor and for producing the desired skin depth may be selected. The alternating current frequency may be adjusted after energizing the inductor to maintain the desired electromagnetic flux skin depth. The desired skin depth may be substantially maintained as the temperature of the material varies. An induction heating apparatus includes a sensor configured to detect changes in at least one physical characteristic of a material to be heated in a crucible, and a controller configured for selectively varying a frequency of an alternating current for energizing an inductor at least partially in response to changes in the physical characteristic to be detected by the sensor.

  20. Time-lapse monitoring of soil water content using electromagnetic conductivity imaging

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The volumetric soil water content (VWC) is fundamental to agriculture. Unfortunately, the universally accepted thermogravimetric method is labour intensive and time-consuming to use for field-scale monitoring. Electromagnetic (EM) induction instruments have proven to be useful in mapping the spatio-...

  1. Monitoring scale-specific and temporal variation in electromagnetic conductivity images

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In the semi-arid and arid landscapes of southwest USA, irrigation sustains agricultural activity; however, there are increasing demands on water resources. As such spatial temporal variation of soil moisture needs to be monitored. One way to do this is to use electromagnetic (EM) induction instrumen...

  2. Electromagnetics laboratory annual report, 1994

    NASA Astrophysics Data System (ADS)

    Lindell, I. V.; Sihvola, A. H.

    1995-01-01

    Activities of the Electromagnetics Laboratory during 1994 are described in this report. As highlights of the output stand the monographs Electromagnetic Waves in Chiral and Bi-Isotropic Media (Artech House, Boston) and History of Electrical Engineering (Otatieto, Espoo, in Finnish). Also, the total number of papers published and accepted for publication in international refereed journals show a new record, 40 items.

  3. Exploration of the Electromagnetic Environment

    ERIC Educational Resources Information Center

    Fullekrug, M.

    2009-01-01

    The electromagnetic environment is composed of electric and magnetic fields which result from man-made and natural sources. An elementary experiment is described to explore the electromagnetic environment by measuring electric fields in the frequency range from approximately equal to 10 to 24 000 Hz. The equipment required to conduct the…

  4. SOME SPECULATIONS ON ELECTROMAGNETIC THEORY,

    DTIC Science & Technology

    An attempt is made to derive Maxwell’s equation of an Electromagnetic field, in vacuo, from the relativistic Liouville’s equation for the photon gas...intensity, while half of the difference of the two functions, divided by square root of (-1) is the magnetic field intensity. Two vector wave functions satisfy Maxwell’s equation of Electromagnetic wave in vacuo. (Author)

  5. Electromagnetic direct implicit PIC simulation

    SciTech Connect

    Langdon, A.B.

    1983-03-29

    Interesting modelling of intense electron flow has been done with implicit particle-in-cell simulation codes. In this report, the direct implicit PIC simulation approach is applied to simulations that include full electromagnetic fields. The resulting algorithm offers advantages relative to moment implicit electromagnetic algorithms and may help in our quest for robust and simpler implicit codes.

  6. Ethiopian Geothermal Resources Inferred from Electromagnetic (AMT/MT, TEM) Data and Seismic Noise Interferometry

    NASA Astrophysics Data System (ADS)

    Lindsey, N. J.; Whaler, K. A.; Johnson, N.; Baptie, B.; Lemma, Y.; Desissa, M.; Ebinger, C. J.; Belachew, M.; Keir, D.; Fisseha, S.; Dawes, G.; Hautot, S.

    2012-12-01

    In Ethiopia, modern energy (hydroelectricity and foreign petroleum) is expensive and unpredictable, yet energy access is key to sustainable development. Active volcanoes and hot springs located in the slow-spreading rift zone of the Afar Depression suggest an abundant geothermal energy resource; however, before this energy can be utilized subsurface geophysical analysis is needed to study the geothermal system, its potential and identify drilling targets. The aim of this project is to use geophysical data (audio-magnetotelluric (AMT), magnetotelluric (MT), transient-electromagnetic (TEM) and passive seismic data), recently recorded in the Northern Tendaho Graben of Afar, Ethiopia, to constrain geothermal system parameters (i.e. geology, temperature, fluid properties, etc.). Recovery of these parameters enables the understanding of reservoir heat flow, geothermal energy potential, economic viability and development of an optimal drilling strategy. The AMT/MT data were recorded at 28 sites along two parallel profiles oriented perpendicular to regional geologic strike. Two-dimensional joint inversion of the TE and TM modes from all sites identifies two very strong conducting layers (~1 Ohm-m), at <500 m and 5-10 km, separated by a more resistive layer (~50 Ohm-m). This model is strongly correlated with borehole information. The deeper high conductivity anomaly shallows toward the center of the profile, at the location of highest recorded fluid temperature from early drilling operations. MT impedance tensor decomposition, phase tensor analysis and induction vector calculations, as well as forward modelling of the inversion results are mutually consistent. Two-dimensional surface wave tomography results from seismic noise interferometry add another layer of geophysical information to this interdisciplinary study, complementing the AMT/MT survey. This project was funded by the US-UK Fulbright Commission and the University of Edinburgh, and benefited from strong

  7. Gravitational scattering of electromagnetic radiation

    NASA Technical Reports Server (NTRS)

    Brooker, J. T.; Janis, A. I.

    1980-01-01

    The scattering of electromagnetic radiation by linearized gravitational fields is studied to second order in a perturbation expansion. The incoming electromagnetic radiation can be of arbitrary multipole structure, and the gravitational fields are also taken to be advanced fields of arbitrary multipole structure. All electromagnetic multipole radiation is found to be scattered by gravitational monopole and time-varying dipole fields. No case has been found, however, in which any electromagnetic multipole radiation is scattered by gravitational fields of quadrupole or higher-order multipole structure. This lack of scattering is established for infinite classes of special cases, and is conjectured to hold in general. The results of the scattering analysis are applied to the case of electromagnetic radiation scattered by a moving mass. It is shown how the mass and velocity may be determined by a knowledge of the incident and scattered radiation.

  8. Electromagnetic containerless processing requirements and recommended facility concept and capabilities for space lab

    NASA Technical Reports Server (NTRS)

    Frost, R. T.; Bloom, H. L.; Napaluch, L. J.; Stockhoff, E. H.; Wouch, G.

    1974-01-01

    Containerless melting, reaction, and solidification experiments and processes which potentially can lead to new understanding of material science and production of new or improved materials in the weightless space environment are reviewed in terms of planning for spacelab. Most of the experiments and processes discussed are amenable to the employment of electromagnetic position control and electromagnetic induction or electron beam heating and melting. The spectrum of relevant properties of materials, which determine requirements for a space laboratory electromagnetic containerless processing facility are reviewed. Appropriate distributions and associated coil structures are analyzed and compared on the basis of efficiency, for providing the functions of position sensing, control, and induction heating. Several coil systems are found capable of providing these functions. Exchangeable modular coils in appropriate sizes are recommended to achieve the maximum power efficiencies, for a wide range of specimen sizes and resistivities, in order to conserve total facility power.

  9. EM Induction Experiment to Determine the Moment of a Magnet

    ERIC Educational Resources Information Center

    Najiya Maryam, K. M.

    2014-01-01

    If we drop a magnet through a coil, an emf is induced in the coil according to Faraday's law of electromagnetic induction. Here, such an experiment is done using expEYES kit. The plot of emf versus time has a specific shape with two peaks. A theoretical analysis of this graph is discussed here for both short and long cylindrical magnets.…

  10. Thrust Stand Measurements of a Conical Inductive Pulsed Plasma Thruster

    NASA Technical Reports Server (NTRS)

    Hallock, Ashley K.; Polzin, Kurt A.

    2013-01-01

    Inductive Pulsed Plasma Thrusters (iPPT) spacecraft propulsion devices in which electrical energy is capacitively stored and then discharged through an inductive coil. The thruster is electrodeless, with a time-varying current in the coil interacting with a plasma covering the face of the coil to induce a plasma current Propellant is accelerated and expelled at a high exhaust velocity (O(10 -- 100 km/s)) by the Lorentz body force arising from the interaction of the magnetic field and the induced plasma current. While this class of thruster mitigates the life-limiting issues associated with electrode erosion, inductive pulsed plasma thrusters can suffer from both high pulse energy requirements imposed by the voltage demands of inductive propellant ionization, and low propellant utilization efficiencies. While this class of thruster mitigates the life-limiting issues associated with electrode erosion, inductive pulsed plasma thrusters can suffer from both high pulse energy requirements imposed by the voltage demands of inductive propellant ionization, and low propellant utilization efficiencies. A conical coil geometry may offer higher propellant utilization efficiency over that of a at inductive coil, however an increase in propellant utilization may be met with a decrease in axial electromagnetic acceleration, and in turn, a decrease in the total axially-directed kinetic energy imparted to the propellant.

  11. Progress in Induction Linacs

    SciTech Connect

    Caporaso, G J

    2000-09-27

    This presentation will be a broad survey of progress in induction technology over the past four years. Much work has been done on accelerators for hydrodynamic test radiography and other applications. Solid-state pulsers have been developed which can provide unprecedented flexibility and precision in pulse format and accelerating voltage for both ion and electron induction machines. Induction linacs can now be built which can operate with MHz repetition rates. Solid-state technology has also made possible the development of fast kickers for precision control of high current beams. New insulator technology has been developed which will improve conventional induction linacs in addition to enabling a new class of high gradient induction linacs.

  12. Principles of Induction Accelerators

    NASA Astrophysics Data System (ADS)

    Briggs*, Richard J.

    The basic concepts involved in induction accelerators are introduced in this chapter. The objective is to provide a foundation for the more detailed coverage of key technology elements and specific applications in the following chapters. A wide variety of induction accelerators are discussed in the following chapters, from the high current linear electron accelerator configurations that have been the main focus of the original developments, to circular configurations like the ion synchrotrons that are the subject of more recent research. The main focus in the present chapter is on the induction module containing the magnetic core that plays the role of a transformer in coupling the pulsed power from the modulator to the charged particle beam. This is the essential common element in all these induction accelerators, and an understanding of the basic processes involved in its operation is the main objective of this chapter. (See [1] for a useful and complementary presentation of the basic principles in induction linacs.)

  13. Electromagnetically revolving sphere viscometer

    NASA Astrophysics Data System (ADS)

    Hosoda, Maiko; Sakai, Keiji

    2014-12-01

    In this paper, we propose a new method of low viscosity measurement, in which the rolling of a probe sphere on the flat solid bottom of a sample cell is driven remotely and the revolution speed of the probe in a sample liquid gives the viscosity measurements. The principle of this method is based on the electromagnetically spinning technique that we developed, and the method is effective especially for viscosity measurements at levels below 100 mPa·s with an accuracy higher than 1%. The probe motion is similar to that in the well-known rolling sphere (ball) method. However, our system enables a steady and continuous measurement of viscosity, which is problematic using the conventional method. We also discuss the limits of the measurable viscosity range common to rolling-sphere-type viscometers by considering the accelerating motion of a probe sphere due to gravity, and we demonstrate the performance of our methods.

  14. Nucleon Electromagnetic Form Factors

    SciTech Connect

    Marc Vanderhaeghen; Charles Perdrisat; Vina Punjabi

    2007-10-01

    There has been much activity in the measurement of the elastic electromagnetic proton and neutron form factors in the last decade, and the quality of the data has greatly improved by performing double polarization experiments, in comparison with previous unpolarized data. Here we review the experimental data base in view of the new results for the proton, and neutron, obtained at JLab, MAMI, and MIT-Bates. The rapid evolution of phenomenological models triggered by these high-precision experiments will be discussed, including the recent progress in the determination of the valence quark generalized parton distributions of the nucleon, as well as the steady rate of improvements made in the lattice QCD calculations.

  15. Electromagnetic scattering theory

    NASA Technical Reports Server (NTRS)

    Bird, J. F.; Farrell, R. A.

    1986-01-01

    Electromagnetic scattering theory is discussed with emphasis on the general stochastic variational principle (SVP) and its applications. The stochastic version of the Schwinger-type variational principle is presented, and explicit expressions for its integrals are considered. Results are summarized for scalar wave scattering from a classic rough-surface model and for vector wave scattering from a random dielectric-body model. Also considered are the selection of trial functions and the variational improvement of the Kirchhoff short-wave approximation appropriate to large size-parameters. Other applications of vector field theory discussed include a general vision theory and the analysis of hydromagnetism induced by ocean motion across the geomagnetic field. Levitational force-torque in the magnetic suspension of the disturbance compensation system (DISCOS), now deployed in NOVA satellites, is also analyzed using the developed theory.

  16. Superconducting electromagnetic thruster

    SciTech Connect

    Meng, J.

    1993-02-11

    An electromagnetic thruster for marine vehicles using a jet of water driven by the interaction of a mutually perpendicular intensified magnetic field and an intensified electric field is disclosed. The intensified magnetic field is produced by superconducting coils cooled by a coolant such as liquid helium. An intensified electric field is produced by passing high amperage current across the seawater jet. These interacting fields produce a Lorentz force perpendicular to mutually perpendicular electric and magnetic field vectors which is used to drive the seawater jet. In some embodiments, the force may also be used to draw water into the jet from the boundary layer flow around the vehicle thereby reducing boundary layer turbulence and associated radiated noise.

  17. On steady electromagnetic equilibria

    NASA Astrophysics Data System (ADS)

    Lehnert, B.

    1986-12-01

    The existence of steady electromagnetic equilibrium states predicted by an extended Lorentz invariant formulation of Maxwell's equations is analyzed. General equilibrium solutions are outlined which lead to integrated field quantities of the system, such as total charge qo, magnetic moment Mo, mass mo and angular momentum so. The quantization of moMo/qo in terms of Bohr magnetons is shown to be equivalent to the proposed resonance condition of circulating self-confined radiation. Exact equilibrium solutions were deduced in two simple cases, thereby leading to a so of the same order as that of the electron, and to a qo one order of magnitude larger than the electronic charge. A variational procedure is suggested in search for states of minimum charge, under the subsidiary quantum conditions on moMo/qo and so, i.e., by varying the profile of the electric space charge distribution.

  18. Computational electronics and electromagnetics

    SciTech Connect

    Shang, C. C.

    1997-02-01

    The Computational Electronics and Electromagnetics thrust area at Lawrence Livermore National Laboratory serves as the focal point for engineering R&D activities for developing computer-based design, analysis, and tools for theory. Key representative applications include design of particle accelerator cells and beamline components; engineering analysis and design of high-power components, photonics, and optoelectronics circuit design; EMI susceptibility analysis; and antenna synthesis. The FY-96 technology-base effort focused code development on (1) accelerator design codes; (2) 3-D massively parallel, object-oriented time-domain EM codes; (3) material models; (4) coupling and application of engineering tools for analysis and design of high-power components; (5) 3-D spectral-domain CEM tools; and (6) enhancement of laser drilling codes. Joint efforts with the Power Conversion Technologies thrust area include development of antenna systems for compact, high-performance radar, in addition to novel, compact Marx generators. 18 refs., 25 figs., 1 tab.

  19. Electromagnetic Gyrokinetic Simulations

    SciTech Connect

    Wan, W

    2003-11-19

    A new electromagnetic kinetic electron {delta} particle simulation model has been demonstrated to work well at large values of plasma {beta} times the ion-to-electron mass ratio. The simulation is three-dimensional using toroidal flux-tube geometry and includes electron-ion collisions. The model shows accurate shear Alfven wave damping and microtearing physics. Zonal flows with kinetic electrons are found to be turbulent with the spectrum peaking at zero and having a width in the frequency range of the driving turbulence. This is in contrast with adiabatic electron cases where the zonal flows are near stationary, even though the linear behavior of the zonal flow is not significantly affected by kinetic electrons. zonal fields are found to be very weak, consistent with theoretical predictions for {beta} below the kinetic ballooning limit. Detailed spectral analysis of the turbulence data is presented in the various limits.

  20. Electromagnetically Clean Solar Arrays

    NASA Technical Reports Server (NTRS)

    Stem, Theodore G.; Kenniston, Anthony E.

    2008-01-01

    The term 'electromagnetically clean solar array' ('EMCSA') refers to a panel that contains a planar array of solar photovoltaic cells and that, in comparison with a functionally equivalent solar-array panel of a type heretofore used on spacecraft, (1) exhibits less electromagnetic interferences to and from other nearby electrical and electronic equipment and (2) can be manufactured at lower cost. The reduction of electromagnetic interferences is effected through a combination of (1) electrically conductive, electrically grounded shielding and (2) reduction of areas of current loops (in order to reduce magnetic moments). The reduction of cost is effected by designing the array to be fabricated as a more nearly unitary structure, using fewer components and fewer process steps. Although EMCSAs were conceived primarily for use on spacecraft they are also potentially advantageous for terrestrial applications in which there are requirements to limit electromagnetic interference. In a conventional solar panel of the type meant to be supplanted by an EMCSA panel, the wiring is normally located on the back side, separated from the cells, thereby giving rise to current loops having significant areas and, consequently, significant magnetic moments. Current-loop geometries are chosen in an effort to balance opposing magnetic moments to limit far-0field magnetic interactions, but the relatively large distances separating current loops makes full cancellation of magnetic fields problematic. The panel is assembled from bare photovoltaic cells by means of multiple sensitive process steps that contribute significantly to cost, especially if electomagnetic cleanliness is desired. The steps include applying a cover glass and electrical-interconnect-cell (CIC) sub-assemble, connecting the CIC subassemblies into strings of series-connected cells, laying down and adhesively bonding the strings onto a panel structure that has been made in a separate multi-step process, and mounting the

  1. Electromagnetic nucleon form factors

    SciTech Connect

    Bender, A.; Roberts, C.D.; Frank, M.R.

    1995-08-01

    The Dyson-Schwinger equation framework is employed to obtain expressions for the electromagnetic nucleon form factor. In generalized impulse approximation the form factor depends on the dressed quark propagator, the dressed quark-photon vertex, which is crucial to ensuring current conservation, and the nucleon Faddeev amplitude. The approach manifestly incorporates the large space-like-q{sup 2} renormalization group properties of QCD and allows a realistic extrapolation to small space-like-q{sup 2}. This extrapolation allows one to relate experimental data to the form of the quark-quark interaction at small space-like-q{sup 2}, which is presently unknown. The approach provides a means of unifying, within a single framework, the treatment of the perturbative and nonperturbative regimes of QCD. The wealth of experimental nucleon form factor data, over a large range of q{sup 2}, ensures that this application will provide an excellent environment to test, improve and extend our approach.

  2. Pulsed electromagnetic gas acceleration

    NASA Technical Reports Server (NTRS)

    Jahn, R. G.; Vonjaskowsky, W. F.; Clark, K. E.

    1971-01-01

    Experimental data were combined with one-dimensional conservation relations to yield information on the energy deposition ratio in a parallel-plate accelerator, where the downstream flow was confined to a constant area channel. Approximately 70% of the total input power was detected in the exhaust flow, of which only about 20% appeared as directed kinetic energy, thus implying that a downstream expansion to convert chamber enthalpy into kinetic energy must be an important aspect of conventional high power MPD arcs. Spectroscopic experiments on a quasi-steady MPD argon accelerator verified the presence of A(III) and the absence of A(I), and indicated an azimuthal structure in the jet related to the mass injection locations. Measurements of pressure in the arc chamber and impact pressure in the exhaust jet using a piezocrystal backed by a Plexiglas rod were in good agreement with the electromagnetic thrust model.

  3. New geophysical electromagnetic method of archeological object research in Egypt

    NASA Astrophysics Data System (ADS)

    Hachay, O. A.; Khachay, O. Yu.; Attia, Magdi.

    2009-04-01

    The demand to the enhanced geophysical technique and device, in addition to the precise interpretation of the geophysical data, is the resolution of the geophysical complex research, especially by the absence of priory information about the researched place. Therefore, an approach to use the planshet method of electromagnetic induction in the frequency geometry was developed by Hachay. et al., 1997a, 1997b, 1999, 2000, 2002, and 2005. The method was adapted to map and monitor the high complicated geological mediums, to determine the structural factors and criteria of the rock massif in the mine subsurface. The field observation and the way of interpretation make the new technology differ from other known earlier methods of field raying or tomography (Hachay et al., 1997c, 1999, and 2000).The 3D geoelectrical medium research is based on the concept of three staged interpreting of the alternating electromagnetic field in a frame of the block-layered isotropic medium with inclusion (Hachay 1997a, and 2002); in the first stage, the geoelectrical parameters of the horizontal block-layered medium, which includes the heterogeneities, are defined. In the second stage a geometrical model of the different local heterogeneities or groups inside the block-layered medium is constructed based on the local geoelectrical heterogeneities produced from the first stage after filtering the anomalous fields plunged in the medium. While in the third stage, the surfaces of the searched heterogeneities could be calculated in account of the physical parameters of the anomalous objects.For practical realization of that conception the system of observation for alternating electromagnetic field with use of vertical magnetic dipole was elaborated. Such local source of excitation and regular net of observations allows realizing overlapping by different angles of observation directions. As incoming data for interpretation, three components of modules of three components of magnetic field are

  4. Forward modeling of geophysical electromagnetic methods using Comsol

    NASA Astrophysics Data System (ADS)

    Butler, S. L.; Zhang, Z.

    2016-02-01

    In geophysical electromagnetic methods, time-varying magnetic fields are measured at Earth's surface that are produced by electrical currents inside the Earth in order to constrain subsurface conductivity and geological structure. These methods are widely used for mineral exploration and environmental investigations, and are increasingly being used in hydrocarbon exploration as well. Forward modeling of exploration geophysics methods is useful for the purpose of survey planning, for understanding the method, especially for students, and as part of an iteration process in inverting measured data. Modeling electromagnetic methods remains an area of active research. In most geophysical methods, the electromagnetic frequency is sufficiently low that the wavelength of the radiation is much larger than the area of interest. As such, the quasi-static approximation is valid. Comsol Multiphysics' AC/DC module solves Maxwell's equations in the quasi-static approximation and in this contribution, we will show examples of its use in modeling magnetometric resistivity (MMR), very low frequency (VLF) techniques, as well as frequency and time-domain induction-based electromagnetic techniques. Solutions are compared with benchmarks from the literature.

  5. Overview of Advanced Electromagnetic Propulsion Development at NASA Glenn Research Center

    NASA Technical Reports Server (NTRS)

    Pencil, Eric J.; Kamhawi, Hani; Gilland, James H.; Arrington, Lynn A.

    2005-01-01

    NASA Glenn Research Center s Very High Power Electric Propulsion task is sponsored by the Energetics Heritage Project. Electric propulsion technologies currently being investigated under this program include pulsed electromagnetic plasma thrusters, magnetoplasmadynamic thrusters, helicon plasma sources as well as the systems models for high power electromagnetic propulsion devices. An investigation and evaluation of pulsed electromagnetic plasma thruster performance at energy levels up to 700 Joules is underway. On-going magnetoplasmadynamic thruster experiments will investigate applied-field performance characteristics of gas-fed MPDs. Plasma characterization of helicon plasma sources will provide additional insights into the operation of this novel propulsion concept. Systems models have been developed for high power electromagnetic propulsion concepts, such as pulsed inductive thrusters and magnetoplasmadynamic thrusters to enable an evaluation of mission-optimized designs.

  6. Measurements of reactor-relevant electromagnetic effects with the FELIX facility

    SciTech Connect

    Turner, L.R.; Hua, T.Q.; Knott, M.J.; Lee, S.Y.; McGhee, D.G.; Wehrle, R.B.

    1986-01-01

    In predicting the electromagnetic consequences of a plasma disruption in a tokamak reactor design, a two-dimensional electromagnetic model of the first wall, blanket, and shield (FWBS) system is typically used. The response to a decaying plasma current is then found to be dominated by a single eddy-current mode, with a single L/R time. Recent experiments with the Fusion ELectromagnetic Induction eXperiment (FELIX) facility at Argonne National Laboratory suggest that such modeling can be used to design against electromagnetic forces and torques, but only if a range of values is used for both tau, the plasma decay time, and tau/sub 0/, the L/R time of the FWBS system.

  7. Numerical analysis of high strain rate failure of electro-magnetically loaded steel sheets

    NASA Astrophysics Data System (ADS)

    Erice, Borja; Mohr, Dirk

    2015-09-01

    Electro-magnetic forces provide a potentially power full means in designing dynamic experiments with active control of the loading conditions. This article deals with the development of computational models to simulate the thermo-mechanical response of electro-magnetically loaded metallic structures. The model assumes linear electromagnetic constitutive equations and time-independent electric induction to estimate the Joule heating and the Lorentz forces. The latter are then taken into account when evaluating stress equilibrium. A thermo-visco-plastic model with Johnson-Cook type of temperature and strain rate dependence and combined Swift-Voce hardening is used to evaluate the material's thermo-mechanical response. As a first application, the model is used to analyse the effect of electro-magnetic loading on the ductility of advanced high strength steels.

  8. Experimental adaptive process tomography

    NASA Astrophysics Data System (ADS)

    Pogorelov, I. A.; Struchalin, G. I.; Straupe, S. S.; Radchenko, I. V.; Kravtsov, K. S.; Kulik, S. P.

    2017-01-01

    Adaptive measurements were recently shown to significantly improve the performance of quantum state tomography. Utilizing information about the system for the online choice of optimal measurements allows one to reach the ultimate bounds of precision for state reconstruction. In this article we generalize an adaptive Bayesian approach to the case of process tomography and experimentally show its superiority in the task of learning unknown quantum operations. Our experiments with photonic polarization qubits cover all types of single-qubit channels. We also discuss instrumental errors and the criteria for evaluation of the ultimate achievable precision in an experiment. It turns out that adaptive tomography provides a lower noise floor in the presence of strong technical noise.

  9. Electromagnetic Field Effects in Explosives

    NASA Astrophysics Data System (ADS)

    Tasker, D. G.; Whitley, V. H.; Lee, R. J.

    2009-12-01

    Present and previous research on the effects of electromagnetic fields on the initiation and detonation of explosives and the electromagnetic properties of explosives are reviewed. Among the topics related to detonating explosives are: enhancement of performance; and control of initiation and growth of reaction. Two series of experiments were performed to determine the effects of 1-T magnetic fields on explosive initiation and growth in the modified gap test and on the propagation of explosively generated plasma into air. The results have implications for the control of reactions in explosives and for the use of electromagnetic particle velocity gauges.

  10. Effect of Inductive Coil Geometry and Current Sheet Trajectory of a Conical Theta Pinch Pulsed Inductive Plasma Accelerator

    NASA Technical Reports Server (NTRS)

    Hallock, Ashley K.; Polzin, Kurt A.; Bonds, Kevin W.; Emsellem, Gregory D.

    2011-01-01

    Results are presented demonstrating the e ect of inductive coil geometry and current sheet trajectory on the exhaust velocity of propellant in conical theta pinch pulsed induc- tive plasma accelerators. The electromagnetic coupling between the inductive coil of the accelerator and a plasma current sheet is simulated, substituting a conical copper frustum for the plasma. The variation of system inductance as a function of plasma position is obtained by displacing the simulated current sheet from the coil while measuring the total inductance of the coil. Four coils of differing geometries were employed, and the total inductance of each coil was measured as a function of the axial displacement of two sep- arate copper frusta both having the same cone angle and length as the coil but with one compressed to a smaller size relative to the coil. The measured relationship between total coil inductance and current sheet position closes a dynamical circuit model that is used to calculate the resulting current sheet velocity for various coil and current sheet con gura- tions. The results of this model, which neglects the pinching contribution to thrust, radial propellant con nement, and plume divergence, indicate that in a conical theta pinch ge- ometry current sheet pinching is detrimental to thruster performance, reducing the kinetic energy of the exhausting propellant by up to 50% (at the upper bound for the parameter range of the study). The decrease in exhaust velocity was larger for coils and simulated current sheets of smaller half cone angles. An upper bound for the pinching contribution to thrust is estimated for typical operating parameters. Measurements of coil inductance for three di erent current sheet pinching conditions are used to estimate the magnetic pressure as a function of current sheet radial compression. The gas-dynamic contribution to axial acceleration is also estimated and shown to not compensate for the decrease in axial electromagnetic acceleration

  11. Emission tomography of the kidney

    SciTech Connect

    Teates, C.D.; Croft, B.Y.; Brenbridge, N.A.; Bray, S.T.; Williamson, B.R.

    1983-12-01

    Single photon emission computerized tomography (SPECT) was done on two patients with suspected renal masses. Nuclear scintigraphy was equivocal on two tumors readily identified by SPECT. Single photon tomography is cost effective and increases the reliability of nuclear scintigraphy.

  12. Field models and numerical dosimetry inside an extremely-low-frequency electromagnetic bioreactor: the theoretical link between the electromagnetically induced mechanical forces and the biological mechanisms of the cell tensegrity.

    PubMed

    Mognaschi, Maria Evelina; Di Barba, Paolo; Magenes, Giovanni; Lenzi, Andrea; Naro, Fabio; Fassina, Lorenzo

    2014-01-01

    We have implemented field models and performed a detailed numerical dosimetry inside our extremely-low-frequency electromagnetic bioreactor which has been successfully used in in vitro Biotechnology and Tissue Engineering researches. The numerical dosimetry permitted to map the magnetic induction field (maximum module equal to about 3.3 mT) and to discuss its biological effects in terms of induced electric currents and induced mechanical forces (compression and traction). So, in the frame of the tensegrity-mechanotransduction theory of Ingber, the study of these electromagnetically induced mechanical forces could be, in our opinion, a powerful tool to understand some effects of the electromagnetic stimulation whose mechanisms remain still elusive.

  13. Properties of inductive reasoning.

    PubMed

    Heit, E

    2000-12-01

    This paper reviews the main psychological phenomena of inductive reasoning, covering 25 years of experimental and model-based research, in particular addressing four questions. First, what makes a case or event generalizable to other cases? Second, what makes a set of cases generalizable? Third, what makes a property or predicate projectable? Fourth, how do psychological models of induction address these results? The key results in inductive reasoning are outlined, and several recent models, including a new Bayesian account, are evaluated with respect to these results. In addition, future directions for experimental and model-based work are proposed.

  14. Direct reading inductance meter

    NASA Technical Reports Server (NTRS)

    Kolby, R. B. (Inventor)

    1977-01-01

    A direct reading inductance meter comprised of a crystal oscillator and an LC tuned oscillator is presented. The oscillators function respectively to generate a reference frequency, f(r), and to generate an initial frequency, f(0), which when mixed produce a difference equal to zero. Upon connecting an inductor of small unknown value in the LC circuit to change its resonant frequency to f(x), a difference frequency (f(r)-f(x)) is produced that is very nearly a linear function of the inductance of the inductor. The difference frequency is measured and displayed on a linear scale in units of inductance.

  15. How induction generators work

    SciTech Connect

    Nailen, R.L.

    1980-06-01

    The operating principles of the induction generator, which is a standard squirrel cage motor in which the shaft is coupled to and driven by an engine or turbine at a rate above its synchronous speed and which, under these conditions, produces electrical power, are described. The advantages of induction generators, e.g., low cost, simplicity, frequency and voltage controlled by the utility system, no synchronizing controls needed, and the advantages of using small induction generators run by wind turbines, small gas turbines and in low head hydro plants are discussed. (LCL)

  16. Interaction of electromagnetic radiation in the 20-200 GHz frequency range with arrays of carbon nanotubes with ferromagnetic nanoparticles.

    PubMed

    Atdayev, Agylych; Danilyuk, Alexander L; Prischepa, Serghej L

    2015-01-01

    The interaction of electromagnetic radiation with a magnetic nanocomposite based on carbon nanotubes (CNT) is considered within the model of distributed random nanoparticles with a core-shell morphology. The approach is based on a system composed of a CNT conducting resistive matrix, ferromagnetic inductive nanoparticles and the capacitive interface between the CNT matrix and the nanoparticles, which form resonance resistive-inductive-capacitive circuits. It is shown that the influence of the resonant circuits leads to the emergence of specific resonances, namely peaks and valleys in the frequency dependence of the permeability of the nanocomposite, and in the frequency dependence of the reflection and transmission of electromagnetic radiation.

  17. SLIM, Short-pulse Technology for High Gradient Induction Accelerators

    SciTech Connect

    Krasnykh, A.; Kardo-Sysoev, A.; Arntz, F.; /Diversified Tech., Bedford

    2009-12-09

    The conclusions of this paper are: (1) The gradient of the SLIM-based technology is believed to be achievable in the same range as it is for the gradient of a modern rf-linac technology ({approx}100 MeV per meter). (2) The SLIM concept is based on the nsec TEM pulse mode operation with no laser or rf systems. (3) Main components of SLIM are not stressed while the energy is pumped into the induction system. Components can accept the hard environment conditions such as a radiation dose, mismatch, hard electromagnetic nose level, etc. Only for several nanoseconds the switch is OFF and produces a stress in the induction system. At that time, the delivery of energy to the beam takes place. (4) The energy in the induction system initially is storied in the magnetic field when the switch is ON. That fact makes another benefit: a low voltage power supplies can be used. The reliability of a lower voltage power supply is higher and they are cheaper. (5) The coreless SLIM concept offers to work in the MHz range of repetition rate. The induction system has the high electric efficiency (much higher than the DWA). (6) The array of lined up and activated SLIM cells is believed to be a solid state structure of novel accelerating technology. The electron-hole plasma in the high power solid state structure is precisely controlled by the electromagnetic process of a pulsed power supply.

  18. Earthquake prediction with electromagnetic phenomena

    SciTech Connect

    Hayakawa, Masashi

    2016-02-01

    Short-term earthquake (EQ) prediction is defined as prospective prediction with the time scale of about one week, which is considered to be one of the most important and urgent topics for the human beings. If this short-term prediction is realized, casualty will be drastically reduced. Unlike the conventional seismic measurement, we proposed the use of electromagnetic phenomena as precursors to EQs in the prediction, and an extensive amount of progress has been achieved in the field of seismo-electromagnetics during the last two decades. This paper deals with the review on this short-term EQ prediction, including the impossibility myth of EQs prediction by seismometers, the reason why we are interested in electromagnetics, the history of seismo-electromagnetics, the ionospheric perturbation as the most promising candidate of EQ prediction, then the future of EQ predictology from two standpoints of a practical science and a pure science, and finally a brief summary.

  19. Electromagnetic Showers at High Energy

    ERIC Educational Resources Information Center

    Loos, J. S.; Dawson, S. L.

    1978-01-01

    Some of the properties of electromagnetic showers observed in an experimental study are illustrated. Experimental data and results from quantum electrodynamics are discussed. Data and theory are compared using computer simulation. (BB)

  20. Conical electromagnetic radiation flux concentrator

    NASA Technical Reports Server (NTRS)

    Miller, E. R.

    1972-01-01

    Concentrator provides method of concentrating a beam of electromagnetic radiation into a smaller beam, presenting a higher flux density. Smaller beam may be made larger by sending radiation through the device in the reverse direction.