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1
Chaudhary, Sumeet. "Lightweight Electromagnetic Induction Motor." University of Cincinnati / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1581333548692675.
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Agutu, Willis Owuor. "Characterization of electromagnetic induction damper." Oxford, Ohio : Miami University, 2007. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=miami1187267117.
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van, Herel Ryan Marinus Johannes Wilhelmus Maria. "Wire Explosion via Electromagnetic Induction." Thesis, University of Canterbury. Electrical and Computer Engineering, 2011. http://hdl.handle.net/10092/6719.
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This research is aimed at exploding a wire via electromagnetic induction, with a preference for obtaining restrike of the exploding wire in a ring shape or otherwise.
Literature on both exploding wire and electromagnetic induction are introduced together. A mathematical framework to describe the wire explosion by induction is formulated from first principles using the idea of magnetic flux linkages. The environment in which the experiments took place is described, with reference to matters of laboratory safety and also measurement of transient electrical current and voltage in the wire explosion by induction. The results describe the approaches taken to explode a wire by induction to obtain a plasma conductor. Voltage and current data
are displayed and described. Throughout this work, there are long-exposure digital photographic images of the experiments taking place. These contribute to determining the outcome of experiments, and support the conclusions. Wires were exploded
by induction in an air-cored mutually coupled coils system, and restrike of those wires was achieved. Electrical characteristics of wire explosion by electromagnetic induction are displayed and discussed based on what is known about straight exploding
wires. Future works involving creation of plasma rings, electromagnetic thrust and exploding wires in vacuum are discussed.
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Agutu, Willis Owuor Mr. "Characterization of electromagnetic induction damper." Miami University / OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=miami1187267117.
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Darrer, Brendan John. "Electromagnetic induction imaging through metallic shields." Thesis, University College London (University of London), 2017. http://discovery.ucl.ac.uk/1537618/.
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Electromagnetic induction imaging has wide potential application in the disciplines of medicine, security, industry, geophysics and scientific research in general. The present study focuses on the applications in the security industry and in particular on providing a new tool for cargo screening in the context of the detection of illicit trafficking of special nuclear materials. The thesis reports a proof-of-concept study of electromagnetic imaging of metallic objects concealed inside electromagnetic enclosures. The sample object is imaged via phase variation measurements between the driver and sensor coils due to inductive coupling between the coils and the object, these images being proportional conductivity maps. For effective imaging through conductive barriers, subtraction of images at different frequencies was carried out in order to isolate the contribution of the concealed object. The present study validates electromagnetic induction imaging for nuclear security applications. The resolution of the system was determined using an edge detection algorithm applied to the images and found to be ~30 mm. The instrumentation employs Helmholtz coils for the driving field and an array of 20 × 20 sensor coils mounted on a wooden apparatus, with fixtures being non-metallic to magnetically isolate the experiment. Further studies were made to determine the compatibility of the modality to image in 3D by imaging Copper and Aluminium disks raised above the sensor array. The experiment gave a positive result being able to detect up to 80 mm depth (lift-off height) for 150 mm diameter disks and up to 40 mm depth for the 20 mm diameter disks. A study was performed to determine the penetrating power of the system by imaging through Aluminium enclosures of varying thickness. It was found that a Copper disk of 40 mm diameter by 2 mm thickness could be imaged through an Aluminium box even when the wall thickness was 20 mm, at 10 to 200 Hz driving frequency.
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Callegary, James Briggs. "Spatial sensitivity of low-induction-number frequency-domain electromagnetic-induction instruments." Diss., The University of Arizona, 2005. http://hdl.handle.net/10150/282901.
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Numerical simulations were used to study spatial averaging in low-induction-number frequency-domain electromagnetic induction (LIN FEM) instruments. Local ( LS) and cumulative (CS) sensitivity were used to analyze three different aspects of LIN FEM spatial sensitivity. LS is the variation in a measured property given a small change at a given location of the property of interest. CS contours are derived from LS and reveal the shape and the fraction of total instrument sensitivity enclosed within the contours. The first study re-evaluated the asymptotic approach to LIN FEM spatial sensitivity. Using this approach, LIN FEM measurements have often been assumed to represent electrical conductivity (sigma) at discreet depths that do not vary with the sigma of the ground. This assumption was tested using simulations of electromagnetic fields in environments with homogeneous and layered sigma distributions. When the induction number was greater than 0.01, the 1-D vertical CS distribution and the depth of investigation varied up to 20% over the range of sigma simulated. As sigma increased, CS contours and depth of investigation decreased in depth. In the second study a small perturbation approach was used to calculate CS distributions so that each distribution is unique to a given LS distribution. CS was summed from regions of high to low LS, and retained information on the magnitude and location of LS. As sigma increased, CS became focused around the highest LS values. The maximum reduction in depth of investigation was about 40% at the highest sigma investigated. In the final study, a series of small, electrically conductive perturbations was simulated in a three-dimensional, homogeneous environment. Three-dimensional LS varied markedly with a large difference between horizontal (HMD) and vertical (VMD) orientations of the transmitter and receiver dipoles. In some regions, the calculated magnetic field intensity with the perturbation was less than that calculated for the host without the perturbation. This occurred for both VMD and HMD orientations of the transmitter. CS contours were highly complex. One dimensional, vertical LS curves extracted from the three-dimensional data were very different from curves from infinite layer simulations.
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Chadwick, P. J. "Studies of body composition by electromagnetic induction." Thesis, Swansea University, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.636219.
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Many of the current techniques of body composition assessment are either unsuitable for seriously ill patients or lacking precision. The disparity in electrical properties of fat and lean tissue suggests that the interaction between an alternating electromagnetic field and the human body could be a new potentially useful way to determine body composition. The purpose of the work described in this thesis was to develop an inexpensive, simple and safe non-invasive electrical technique of body composition assessment. A large coil, carrying an alternating current, produces an electromagnetic field within its volume. When a subject is placed inside the coil, the field configuration is disturbed and a corresponding change in the electrical behaviour of the coil can be observed. A theoretical analysis based on a helical waveguide model has allowed succesful prediction of the electrical behaviour of the coil when empty and also when it contains a simple homogeneous cylindrical phantom. A prototype helical waveguide system has been constructed, and the measured electric and magnetic field distributions in the coil compared with the theoretical predictions. The ability of the technique to discriminate between simple phantoms with electrical conductivities typical of muscle and of adipose tissue and between phantoms of the same conductivity but different volume has been confirmed experimentally. The suitability of the helical waveguide system for the determination of body composition in vivo has been assessed in a clinical trial involving 45 normal healthy volunteers (22 male, 23 female) ranging in age from 17 to 71 and in weight from 44 to 104 kg. Good correlations were found between changes in the electrical behaviour of the coil and fat-free mass predicted by three accepted techniques of body composition analysis.
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Fontes, Sergio Luiz. "Electromagnetic induction studies in the Italian Alps." Thesis, University of Edinburgh, 1988. http://hdl.handle.net/1842/13836.
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Chilaka, Venkata Sailaja Riggs Lloyd Stephen. "Electromagnetic induction systems for discrimination among metallic targets." Auburn, Ala., 2006. http://repo.lib.auburn.edu/2006%20Spring/doctoral/CHILAKA_SAILAJA_59.pdf.
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Barrowes, Benjamin E. 1973. "Electromagnetic scattering and induction models for spheroidal geometries." Thesis, Massachusetts Institute of Technology, 2004. http://hdl.handle.net/1721.1/16611.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2004.Vita.
Includes bibliographical references (p. 271-280).
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Electromagnetic scattering from a medium containing randomly distributed discrete dielectric spheroidal inclusions is studied. Also, the broadband magnetoquasistatic solution for the induced magnetic field from a conducting and permeable spheroid under time harmonic excitation is demonstrated. Analytical electromagnetic solutions for spheroidal geometries are desirable because of their versatility in modeling manmade and natural shapes includ- ing solid and hollow needles, spheres, and disks, while at the same time possessing analytic solutions. Coherent scattering from a collection of small dielectric spheroids populating a dense medium is compared to scattering from a homogeneous sphere. A Method of Moments (MoM) solution is adopted which accounts for spheroid-spheroid interactions directly. Coherent scattering results from these collections are compared to Mie scattering and the effective permittivity of the dense medium is obtained. Results are in good agreement to the classical mixing formula and this lends credibility to both models. In order to reduce memory requirements and computational complexity, the Sparse Matrix/Canonical Grid (SMCG) method is applied to 3-D dense media scattering. By approximating the dyadic Green's function about a canonical rectilinear grid, weak interaction between spheroid far apart may be quickly approximated. Strong interactions between dielectric spheroid in close proximity are still calculated directly. Weak interactions are quickly evaluated using a novel multilevel block-Toeplitz matrix vector multiply based on the Fast Fourier Transform.
(cont.) Electromagnetic induction (EMI) models of conducting and permeable spheroids under time harmonic excitation are refined to produce the broadband response with high dependability. A hybrid method is constructed consisting of three different approaches: 1) at low frequencies, the formally exact (but truncated) solution is applied, 2) at moderate frequencies, asymptotic expansions of the spheroidal wave functions (SWFs) are employed, 3) and at high, but still magnetoquasistatic, frequencies, a Small Penetration Approximation is borrowed. The combined EMI response is accurate except near a switchover point where there is typically less than a two percent error. Results are compared to data from a set of 17 steel and aluminum machined spheroids taken by the GEM-3 instrument and found to be in excellent agreement. Asymptotic expressions of the SWFs are found to depend on branch points and associated characteristic eigenvalues of the spheroidal wave equation. These branch points are found using polynomial estimation techniques and a quadruple precision Newton-Rhapson search method. Branch points for (n - m) =/< 100 are found in greater accuracy than previously available and many are tabulated in this thesis. The solution for the induced magnetic field from multiple permeable and conducting spheroidal objects in close proximity under time harmonic excitation is presented. Interactions between spheroids is accounted for by a interspheroidal modal interaction matrix. This multibody solution may provide the basis for a forward model used by inversion routines designed to detect and discriminate UXO. Specifically, this multibody solution may help to isolate non-UXO clutter from actual UXO in the field.
by Benjamin Earl Barrowes.
Ph.D.
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Jones, Philip Charles. "An electromagnetic induction study of south Cornwall, England." Thesis, University of Edinburgh, 1992. http://hdl.handle.net/1842/15124.
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Twenty one magnetotelluric and 16 magnetovariation soundings were taken on or near the Carnmenellis granite over periods in the range of 0.0078 seconds to 3000 seconds. The measured impedance tensors were analysed in detail using decomposition methods. All the data are distorted by galvanic electric charges which build up on the granite country rock contact. The amount of distortion varies between sites with distance from the edge of the batholith. The vast majority of the data are at least two dimensional and the effects of three dimensional induction are increasingly sensed by periods greater than 1s. Short period soundings indicate that the anisotropy in the magnetotelluric field is caused by electric current being channelled along fluid filled cracks. One dimensional modelling of the E-pol response indicates that the bottom of the granite is not flat, but slopes downwards to the south. This finding is evidence to support the theory that the Cornubrian granites originated SSE of their present position and were rafted NNW as a thin sheet. Two dimensional modelling suggests that at least a portion of the gradient of this slope is caused by the neglection of 3D induction in models used in the study. The pattern of regional azimuths between 0.1 and 10 seconds is caused by a combination of lateral, near surface, conductivity contrast, such as the surrounding seas, and conductivity contrasts at depth due to the slope of the bottom of the granite. Mainly due to the effects of conductivity contrasts perpendicular to the regional azimuth, it was found impossible to find a model which fitted the E-pol data at both on and off granite sites. The 2D model indicates that there is a steep rise in the resistivity depth profile of the granite from 800 ohm-m at the surface to 20000 ohm-m at 4 km. The closure of fluid filled joints due to the increase in lithological load with depth is interpreted to be the cause of this increase in resistivity.
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Wei, Mu-Hsin. "Electromagnetic induction spectroscopy for the detection of subsurface targets." Diss., Georgia Institute of Technology, 2012. http://hdl.handle.net/1853/45896.
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This thesis presents a robust method for estimating the relaxations of a metallic object from its electromagnetic induction (EMI) response. The EMI response of a metallic object can be accurately modeled by a sum of real decaying exponentials. However, it is difficult to obtain the model parameters from measurements when the number of exponentials in the sum is unknown or the terms are strongly correlated. Traditionally, the relaxation constants are estimated by nonlinear iterative search that often leads to unsatisfactory results.
An effective EMI modeling technique is developed by first linearizing the problem through enumeration and then solving the linearized model using a sparsity-regularized minimization.
This approach overcomes several long-standing challenges in EMI signal modeling, including finding the unknown model order as well as handling the ill-posed nature of the problem. The resulting algorithm does not require a good initial guess to converge to a satisfactory solution.
This new modeling technique is extended to incorporate multiple measurements in a single parameter estimation step. More accurate estimates are obtained by exploiting an invariance property of the EMI response, which states that the relaxation frequencies do not change for different locations and orientations of a metallic object. Using tests on synthetic data and laboratory measurement of known targets, the proposed multiple-measurement method is shown to provide accurate and stable estimates of the model parameters.
The ability to estimate the relaxation constants of targets enables more robust subsurface target discrimination using the relaxations. A simple relaxation-based subsurface target detection algorithm is developed to demonstrate the potential of the estimated relaxations.
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Ktistis, Christos. "Electromagnetic induction tomography techniques for low conductivity biomedical application." Thesis, University of Manchester, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.682783.
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This thesis considers the feasibility of using magnetic inductance tomography (MIT) to reconstruct images which represent the internal conductivity distribution of low contrast objects. The research focuses on a biomedical application, namely the measurement of human body composition. The thesis describes the development of a system which combines a photonic scanner for measuring the shape of the subject, with an experimental MIT system. The shape information can be used as a priori knowledge for the image reconstruction algorithm. The MIT system contained a full-scale 16 coil, circular sensor array, with 8 coils used for excitation and 8 for detection. The diameter of the object space was 75 cm and a commercial data acquisition system was used to interrogate the array. The measured data was reconstructed using linear algorithms and two kinds of sensitivity maps, one computed without shape information and the other with. The thesis contains results from a variety of tests illustrating the limits of each and the importance of knowing the external shape of the object. The shape scanning system is operating on the structured light principle. It consisted of four cameras and the 8 laser line generators which were integrated in the same scanning mechanisms used by the MIT system. Experiments were preformed in order to verify if the current design was capable to capture and reconstruct human body shape. Overall, the results of the research undertaken for this thesis support the feasibility of reconstructing internal features however more work is needed to obtain images of sufficient quality.
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Burke, Robert Adrian. "Study of a single-stage electromagnetic launcher." Thesis, Loughborough University, 1997. https://dspace.lboro.ac.uk/2134/17674.
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This thesis examines a single-stage barrel-less electromagnetic induction launcher, developed from an arrangement used previously for very high speed, low projectile mass accelerators. The projectile is placed on top of the launch coil, rather than inside the coil, as is more usually the case in both single and multi-stage launchers of this type. The examination is undertaken both theoretically and experimentally, with extensive experimental results being used to test the validity of the theoretical techniques used. The theoretical examination of the launcher is based on two distinct mathematical models, with results provided by the two approaches being compared. The first model uses a 2D electromagnetic finite-element approach, and does not include projectile motion or thermal effects. It is used to establish whether an analysis technique which does not take into account the projectile dynamics is a valid design tool for a single-stage launcher. The second model employs a coupled-circuit approach to take into account both projectile motion and thermal effects, and is used to obtain an accurate estimate of the overall launcher performance. With the aid of the two models the effects of varying many different launcher parameters are examined, including the size and shape of the stator coil and the size, shape and composition of the projectile. The launcher investigation could be based on a number of criteria but here it is primarily based on two; the highest average velocity over a given distance and the shortest time required to travel a given distance from the initial stationary position.
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Abdu, Hiruy. "Characterizing Subsurface Textural Properties Using Electromagnetic Induction Mapping and Geostatistics." DigitalCommons@USU, 2009. https://digitalcommons.usu.edu/etd/301.
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Knowledge of the spatial distribution of soil textural properties at the watershed scale is important for understanding spatial patterns of water movement, and in determining soil moisture storage and soil hydraulic transport properties. Capturing the heterogeneous nature of the subsurface without exhaustive and costly sampling presents a significant challenge. Soil scientists and geologists have adapted geophysical methods that measure a surrogate property related to the vital underlying process. Apparent electrical conductivity (ECa) is such a proxy, providing a measure of charge mobility due to application of an electric field, and is highly correlated to the electrical conductivity of the soil solution, clay percentage, and water content. Electromagnetic induction (EMI) provides the possibility of obtaining high resolution images of ECa across a landscape to identify subtle changes in subsurface properties. The aim of this study was to better characterize subsurface textural properties using EMI mapping and geostatistical analysis techniques. The effect of variable temperature environments on EMI instrumental response, and ECa - depth relationship were first determined. Then a procedure of repeated EMI mapping at varying soil water content was developed and integrated with temporal stability analysis to capture the time invariant properties of spatial soil texture on an agricultural field. In addition, an EMI imaging approach of densely sampling the subsurface of the Reynolds Mountain East watershed was presented using kriging to interpolate, and Sequential Gaussian Simulation to estimate the uncertainty in the maps. Due to the relative time-invariant characteristics of textural properties, it was possible to correlate clay samples collected over three seasons to ECa data of one mapping event. Kriging methods [ordinary kriging (OK), cokriging (CK), and regression kriging (RK)] were then used to integrate various levels of information (clay percentage, ECa, and spatial location) to produce clay percentage prediction maps. Leave-one-out cross-validation showed that the multivariate estimation methods CK and RK, incorporating the better sampled surrogate ECa, were able to improve the RMSE by 7% and 28%, respectively, relative to OK. Electromagnetic induction measurements provide an important exhaustive layer of information that can improve the quality and resolution of soil property maps used in hydrological and environmental research.
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Jain, Neha Riggs Lloyd Stephen. "A study of electromagnetic induction systems for the detection of unexploded ordnance." Auburn, Ala, 2008. http://repo.lib.auburn.edu/EtdRoot/2008/SPRING/Electrical_and_Computer_Engineering/Thesis/Jain_Neha_0.pdf.
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Goldblatt, William M. "Electromagnetic induction sensing of individual tracer particles in a circulating fluidized bed." Thesis, University of British Columbia, 1990. http://hdl.handle.net/2429/30918.
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Understanding the trajectories of particulate solids inside a flow-through reactor, such as the riser of a recirculating fluidized bed, is a basic requisite to accurately modelling the reactor. However, these trajectories, which are complicated by gross internal recirculation,
are not readily measurable. Conventional means of measuring the residence time distribution can be applied to closed boundaries, such as the exit of the riser. Doing so, however, does not directly provide the details of the trajectories within the riser. In order to determine these trajectories, meaningful measurements must be made at the open boundaries between the adjacent axial regions which, in total, make up the riser. Transient tracer concentration measurements at open boundaries are ambiguous because, as tracer material recirculates past the sensor, its concentration is repeatedly recorded, with no distinction as to which region (above or below the boundary) it has just resided in.
A method designed to eliminate this ambiguity at open boundaries is reported in this thesis. By repeatedly introducing single tracer particles into the riser, and measuring the time of passage through each axial region, the residence time distributions for each region can be obtained from the frequency density of these times. The crux of this approach is being able to sense individual tracer particles. The major thrust of this investigation has been to find a practical means to this end. The final sensor considered in this investigation is based on electromagnetic induction: a magnetic primary field induces an eddy current in a conductive tracer particle, and the resulting secondary field is sensed, indicating the presence of the tracer particle in the sensing volume. Noise, resulting from direct coupling between transmitter and receiver coils, electrostatics, and vibrations, determines the sensitivity of the device. The final prototype sensor is limited in sensitivity to relatively large tracer particles, and it is incapable of measuring tracer velocity. Nevertheless, the trajectory of large particles is of practical significance for circulating fluidized beds. Limited tests were conducted in a 0.15 m ID x 9.14 m tall acrylic riser where the tracer particles were injected opposite the solids re-entry point, and were sensed by a single sensor located at an open boundary 7.5 m downstream. At each of the two superficial gas velocities considered, and above a threshold solids flux, the time-of-flight frequency density between the injector and the sensor for these large tracer particles does not change with increasing flux of the fine solids. This result is incongruous with obvious changes in the macro-flow structure occurring in the riser.
Recommended changes in the sensor would allow measurement of the direction and speed of the tracer, as it passes by the sensor, as well as potentially reducing noise. With these improvements, it would be useful to install multiple sensors along the full length of
the riser. The information obtainable from such a configuration would greatly enhance understanding of the detailed trajectories within the riser.Applied Science, Faculty of
Chemical and Biological Engineering, Department of
Graduate
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Wei, Mu-Hsin. "Estimation of the discrete spectrum of relaxations for electromagnetic induction responses." Thesis, Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/39534.
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This thesis presents a robust method for estimating the relaxations of a metallic object from its electromagnetic induction (EMI) response. The EMI response of a metallic object can be accurately modeled by a sum of real decaying exponentials. However, it is diffcult to obtain the model parameters from measurements when the number of exponentials in the sum is unknown or the terms are strongly correlated. Traditionally, the time constants and residues are estimated by nonlinear iterative search that often leads to unsatisfactory results. In this thesis, a constrained linear method of estimating the parameters is formulated by enumerating the relaxation parameter space and imposing a nonnegative constraint on the parameters. The resulting algorithm does not depend on a good initial guess to converge to a solution. Using tests on synthetic data and laboratory measurement of known targets the proposed method is shown to provide accurate and stable estimates of the model parameters.
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Matandirotya, Electdom. "Measurement and modelling of geomagnetically induced currents (GIC) in power lines." Thesis, Cape Peninsula University of Technology, 2016. http://hdl.handle.net/20.500.11838/2459.
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Thesis (DTech (Electrical Engineering))--Cape Peninsula University of Technology, 2016.Geomagnetically induced currents (GIC) are currents induced in ground-based conductor networks in the Earth's surface. The GIC are driven by an electric eld induced by geomagnetic variations which are a result of time-varying magnetospheric-ionospheric currents during adverse space weather events. Several studies have shown that there is a likelihood of technological damage (the power grid) in the mid- and low-latitude regions that could be linked to GIC during some geomagnetic storms over the past solar cycles. The effects of GIC in the power system can range from temporary damage (e.g. protective relay tripping) to permanent damage (thermal transformer damage). Measurements of GIC in most substations are done on the neutral-to-ground connections of transformers using Hall-effect transducers. However, there is a need to understand the characteristics of GIC in the power lines connected to these transformers. Direct measurements of GIC in the power lines are not feasible due to the low frequencies of these currents which make current measurements using current transformers (CT) impractical. This thesis discusses two techniques that can be employed to enhance understanding GIC characteristics in mid-latitude regions. The techniques involve the measurement of GIC in a power line using differential magnetometer measurements and modelling GIC using the finite element method. Low frequency magnetometers are used to measure magnetic felds in the vicinity of the power lines and the GIC is inferred using the Biot-Savart law. A finite element model, using COMSOL-Multiphysics, is used to calculate GIC with the measured magnetic field and a realistic Earth conductivity profile as inputs. The finite element model is used for the computation of electric field associated with GIC modelling.
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Astfalck, Allen Electrical Engineering Australian Defence Force Academy UNSW. "Analysis of electromagnetic force and noise in inverter driven induction motors." Awarded by:University of New South Wales - Australian Defence Force Academy. School of Electrical Engineering, 2002. http://handle.unsw.edu.au/1959.4/38671.
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This thesis is part of a major research project to analyse vibro-acoustic characteristics from variable speed inverter driven induction motors (VSIDIM). The overall projects??? aimed at providing a better understanding of the mechanisms of sound generation from electromagnetic origins and developing a numerical model to predict the sound power emitted from a VSIDIM. The scope of this thesis is to assess experimentally the effect of various controller strategies on the radiated sound power and to develop a finite element method for calculating the electromagnetic force distribution over the stator. Various sources of noise in induction motors and their behaviour with speed and load have been reviewed. Models of the electromagnetic field and vibro-acoustic character have been discussed. An outline of various techniques of reducing noise in induction motors through design of inverters and modifications to the motor structure has been given. Experiments were conducted to assess the effect of controller strategies on the radiated sound power. Three different supplies were tested: a dynamotor which produces an almost sinusoidal supply with very low harmonic content, an inverter with a low switching frequency (less than 1kHz) and an inverter with a high switching frequency (8kHz) and various levels of random modulation. Results indicate that the sound power level of the MSC drive is a lot higher than that of the VSC 2000 drive and the dynamotor drive. The sound power level of the VSC 2000 drive and the dynamotor drive increases almost linearly with motor speed, that for the MSC drive is almost independent of speed. The sound power level of the MSC drive is almost 28dB higher than that of the dynamotor drive at 450rpm and the difference is reduced to 14dB at 1500rpm where the aerodynamic noise becomes more dominant. It has been found that at the rated speed (1500rpm), the sound power level varies by less than 3dB from no load to full load for all three sources. Although increasing the switching frequency increases the cost of the inverters and switching losses, results from the MSC and VSC 2000 drives clearly show that it reduces the radiated sound power by shifting the harmonics into higher and inaudible frequency range. The tonal nature around the switching frequency has been reduced by increasing the levels of random modulation to spread the energy over a wider range of frequencies, although the sound power level has not varied by more than 0.2dB. A finite element model has been developed to calculate the electromagnetic force distribution. The quasi-static solution method has been implemented by stepping the rotor through the time domain using a fine regular mesh in the air gap. The stator currents were experimentally obtained while the rotor currents were obtained using a 4 parameter state space model of the motor. Results of the simulation indicate the influence of stator and rotor slots, saturation and time harmonics in the current. The calculated electromagnetic force distribution has been used in a FEM/BEM acoustic model and SEA acoustic model to predict the radiated sound power which agrees reasonably well with the measured sound, thus validating indirectly the electromagnetic force simulations.
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Guilizzoni, Roberta. "A resonant system for electromagnetic induction imaging of concealed conductive targets." Thesis, University College London (University of London), 2018. http://discovery.ucl.ac.uk/10045578/.
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The possibility of revealing the presence and identifying the nature of electrically conductive targets is of central interest in many fields, including security, medicine, industry, archaeology and geophysics. In many applications, these targets are electromagnetically shielded by other external materials and thus cannot be directly accessed and detected. Hence, material interrogation techniques are required that allow penetration through the shielding materials, in order for the targets to be identified. Electromagnetic interrogation techniques represent a powerful solution to this challenge, as they enable penetration through conductive shields. Two resonant electromagnetic induction imaging (EII) methods, based on the use of LCR circuits, were developed in this research work. These proof-of-principle EII methods were based, respectively, on position-resolved-measurements of resonant frequency and Q-factor shifts, which occurred as a consequence of eddy current induction inside the conductive targets to be detected. The proposed techniques were applied to 2D imaging of conductive targets (having conductivities σ ranging from 0.54 to 59.77 MSm-1), both unshielded and shielded by an aluminium shield (1.5-mm-thick). The experimental results achieved in the first part of this work highlighted a limitation in the LCR resonant circuits used for EII investigations, linked to the Q-factor low absolute 5 values (between 7 and 23). Therefore, investigations were conducted, leading to the implementation of an improved version of the EII system, based on active bandpass filters. The sensitivity of the novel EII system was found to be larger by a factor of 3.5 compared to the previously used LCR-based system, when both systems were used for imaging copper. Additionally, the new system allowed achieving images with higher contrast. The research work reported in this thesis led to establishing a proof-of-principle method for EII of conductive samples, also in the interesting scenario where the samples were shielded by conductive shields preventing them from being directly accessed.
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Pal, Mayur. "Modeling of induction stirred ladles." Licentiate thesis, KTH, Tillämpad processmetallurgi, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-97895.
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Over the years numerous computational fluid dynamics models have been developed in order to study the fluid flow in gas and induction stirred ladles. These models are used to gain insight in the industrial processes used in ladle treatment of steel. A unified model of an induction stirred Ladle in two and three dimensions is presented. Induction stirring of molten steel is a coupled multi-physics phenomena involving electromagnetic and fluid flow. Models presented in this thesis gives a more accurate description of the real stirring conditions and flow pattern, by taking into account the multi-physics behavior of the induction stirring process in an induction stirred ladle. This thesis presents a formulation of coupled electromagnetic and fluid flow equations. The coupled electromagnetic and fluid flow equations are solved using the finite element method in two and three-dimensions. The simulation model is used to predict values of steel velocities and magnetic flux density. The simulation model is also used to predict the effect of increased current density on flow velocity. Magnetic flux density values obtained from the model are verified against experimental values.QC 20120615
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Fox, Miranda Lynn. "Identifying soils with potential of expanding sulfate mineral formation using electromagnetic induction." Texas A&M University, 2004. http://hdl.handle.net/1969.1/1171.
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Sulfate-bearing soils are a problem in highway construction as they combine with materials used for lime stabilization to form minerals, particularly ettringite, that expand and induce heave in the stabilized soil. This research involves quantifying sulfate in soils that may be potentially used in highway construction using electromagnetic induction. The objectives are to: 1) document electrical conductivity (EC) variability within selected sites that contain sulfate-bearing materials, and 2) determine if electromagnetic induction has potential for locating hazardous levels of sulfate-bearing materials.
The 0.43 ha study area is located in the Blackland Prairies and is a Vertisol known to contain gypsum at the time of site selection. Apparent EC using a model EM38 electromagnetic induction instrument was measured at 200 locations in July and November 2003, using a sampling grid with 5-m spacings. Representative rows and columns were selected from the map of apparent electrical conductivity, and soil cores taken to a depth of 1.5 m at 29 points. Soil samples were obtained by dividing cores into depth increments of 0 to 25 cm, 25 to 75 cm, and 75 to 150 cm. Laboratory analyses were run for each sample and included moisture content, EC and soluble cations and anions of the saturated paste extract, and percent gypsum. Elevation measurements were made to determine if changes in elevation related to EC measurements.
Apparent EC proved to be more successful at detecting soluble salts during the dry sampling period (July) when the effect of soil moisture content was less. For July data, EC and gypsum were significantly correlated in the deepest samples (r2 = 0.51 and 0.15, respectively) to apparent EC. Further, soluble sulfate was significantly correlated to apparent EC (r2 = 0.30) at a depth of 25 to 75 cm. Results suggest that the EM38 can be used successfully to map variability of soil salinity across a field, but although correlation exists between apparent EC and sulfate-bearing materials, it is not sufficiently strong to serve as a good predictor for conditions surrounding lime-induced heave in soil.
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Gonzalez, Rabal Elena. "Exploring electromagnetic induction as a power source for interactive human-powered devices." Thesis, KTH, Skolan för elektroteknik och datavetenskap (EECS), 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-287448.
Full textAbstract:
In the last decade, we have seen an increasing interest in the designing of interactive technology that is limited in energy usage to our bodily capabilities. This field is commonly referred to as Human-Power Interaction (HPI). The aim of HPI is to create battery-free devices that are powered solely from human interactions. Therefore, it is important that power generation and interactivity are aligned and not separated tasks. In this paper, a novel way of providing human power to interactive devices has been investigated using electromagnetic induction. The focus has been to explore and play with the fundamental principles of electromagnetic induction with the intention of evaluating its potential as a new type of interactive power generation. With the help of a physical prototype and an application to demonstrate its capabilities, the results show that electromagnetic induction could potentially be considered as a relatively easy way to build human-powered sources for interactive devices using this principle.Under det senaste decenniet har vi sett ett ökande intresse för utformningen av interaktiv teknik som är begränsad i energianvändningen till det av våra kroppsliga förmågor. Detta fält kallas vanligen Human-Power Interaction (HPI). Målet med HPI är att skapa batterifria enheter som drivs enbart från mänskliga interaktioner. Därför är det viktigt att kraftproduktion och interaktivitet är anpassade till varandra och inte separerade aktiviteter. I denna rapport har ett nytt sätt att tillhandahålla mänsklig kraft till interaktiva enheter undersökts med hjälp av elektromagnetisk induktion. Fokus har varit att utforska och leka med de grundläggande principerna för elektromagnetisk induktion i avsikt att utvärdera dess potential som en ny typ av interaktiv kraftproduktion. Med hjälp av en fysisk prototyp och en tillämpning för att demonstrera dess förmåga, visar resultaten att elektromagnetisk induktion potentiellt kan ses som ett relativt enkelt sätt att bygga människodrivna källor för interaktiva enheter med denna princip.
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Ali, Maythem. "Development of an electromagnetic induction method for non-invasive blood flow measurement." Thesis, University of Huddersfield, 2016. http://eprints.hud.ac.uk/id/eprint/28706/.
Full textAbstract:
Blood flow is an important measurement in the diagnosis of cardiovascular diseases – the main cause of death globally. Cardiovascular diseases are often associated with atherosclerosis, which is a condition that causes the narrowing of arteries due to a buildup of lipids on the wall of the arterial vessels. Atherosclerosis occurring in the upper or lower limbs (referred to as peripheral arterial diseases) may lead to heart attack, stroke or severe health complications. Early detection of peripheral arterial diseases will enable primary prevention, and thus a reduction in morbidity, mortality and associated resources and financial costs. Limitations and drawbacks in the current methods for peripheral arterial blood flow measurement were primary factors in directing this research, which focuses on developing a reliable, easy-to-use and low-cost, non-invasive blood flow metering method that can replace or be an alternative option to current methods. This thesis describes the design and development of a novel electromagnetic induction method that can be used for peripheral arterial blood flow measurement non-invasively. In general terms, an electromagnetic induction flow metering technique is desirable because it is linear and insensitive to viscosity, temperature, conductivity and pressure loss. Additionally, and unlike previous non-invasive electromagnetic blood flow meters, the proposed method can be calibrated offline and is insensitive to velocity profile. The latter is important in obtaining measurements with high accuracy as blood flow in mammals is asymmetric. A mathematical model was developed for the proposed electromagnetic induction method based on the theory of “weight functions” by Shercliff and the “virtual current” theory by Bevir. This model demonstrated that, for multiple flow channels within a cross-sectional area bounded by a multi-electrode array and across which a uniform magnetic field is applied, flow induced potentials, due to the flow interaction with the magnetic field, can be predicted. From these flow induced potentials, the total volumetric flow rate can be found, irrespective of the number, size and location of the flow channels within the area bounded by the electrode array using a technique based on the Discrete Fourier Transform method. This proposed method allows the venous and arterial blood flow in a limb to be found. Next, a finite element model was developed in COMSOL Multiphysics software to validate the theoretical work. This was achieved by modelling multiple flow channels within a cylindrical region and obtaining flow induced potentials, which were compared with the theoretical values. From these induced potentials, the volumetric flow rate was found, using the DFT method, and confirmed. Finally, a practical model was designed and built which consisted of a physical pipework model (simulating a human limb), an electromagnet and signal conditioning and processing systems. Flow induced potential difference measurements were made using this model and compared with the predicted theoretical values. Overall, a good agreement was found between the theoretical results, computer simulations and practical results. Based on this work and additional work that is suggested in thisresearch, a medical prototype non-invasive electromagnetic blood flow meter device can be developed for clinical trials.
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Ibrahim, Mohammad. "Wireless Inductive Charging for Electrical Vehicules : Electromagnetic Modelling and Interoperability Analysis." Thesis, Paris 11, 2014. http://www.theses.fr/2014PA112369/document.
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Le développement de la recharge sans contact de batteries comporte divers avantages pour les véhicules électriques. Cette solution est facile à utiliser, robuste et résistante aux intempéries par rapport aux câbles généralement utilisés. Le principe est basé sur le couplage magnétique entre un émetteur et un récepteur. L'objectif de cette thèse est de contribuer à proposer une norme pour permettre l’interopérabilité, c’est-à-dire, permettre à plusieurs émetteurs de fonctionner avec des récepteurs de différents fournisseurs. Comme le système doit aussi être tolérant au positionnement et doit respecter les recommandations concernant l’exposition humaine, de nombreuses configurations doivent être envisagées. Dans cette thèse, une modélisation avancée et fiable du système complet est proposée. La méthode des éléments finis est exploitée pour déterminer les caractéristiques électriques du coupleur inductif (inductances propres et mutuelles, facteur de couplage) dans différentes configurations de positionnement et d’interopérabilité. Ces valeurs permettent le dimensionnement du convertisseur à résonance. A ce stade différentes topologies de compensation sont considérées. Un modèle analytique au premier harmonique est mis en œuvre pour comparer les topologies et déterminer la fréquence de résonance globale du système. Un modèle circuit du système complet est ensuite développé pour évaluer précisément les courants et tensions. Enfin, un algorithme de régulation basé sur une méthode MPPT (Maximum Power Point Tracking) est évalué pour le réglage automatique de fréquence. A partir des courants calculés à la fréquence de résonance pour un point de fonctionnement nominal et grâce au modèle éléments finis incluant le châssis du véhicule le champ magnétique rayonné est calculé et comparé aux valeurs limites recommandées. A chaque étape de la modélisation, la sensibilité du système aux paramètres de configuration (positionnement, interopérabilité) est analysée. Des mesures effectuées au niveau du coupleur inductif et sur le système complet sont aussi utilisées dans l’analyse et permettent de valider le modèleDevelopment of contactless battery charging is an opportunity for electric vehicles. Compared to regular plugin cables, this solution is easy to use, robust and weather resistant. The power is transferred thanks to the magnetic coupling of inductive coils and a reduced magnetic circuit. The aim of this thesis is to contribute to propose a standard that would make possible to couple emitters with receivers from different suppliers, that is, to insure interoperability. As the system should also be tolerant to positioning and should respect human exposure recommendations, many configurations must be tested. In this thesis, an advanced and reliable modeling of the whole system is proposed. Using the finite element methods, the electrical characteristics (self, mutual inductances and coupling factor) of the inductive coupler are computed for different geometric and interoperability configurations. These values allow the dimensioning of the resonant converter. At this stage, different compensation topologies are considered. It is shown that the global resonant frequency can be derived and the topologies compared from a classical first harmonic approximation and analytical model. Then, a circuit model of the full system is developed in order to evaluate precisely the currents and voltages. Finally, the performance of a Maximum Power Point Tracking as frequency regulation algorithm is evaluated. From the currents computed at resonant frequency for the nominal operating point and the finite element model of the coupler, including the chassis of the vehicle, the radiated magnetic field is evaluated in order to check safety compliance. At each step of the modeling, the sensitivity of the system to the configuration parameters (positioning, interoperability) is analyzed. Measurements at the coupler level and for the full system are also used in this analysis and allow validating the model
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Stalnaker, Jack Lee. "A finite element approach to the 3D CSEM modeling problem and applications to the study of the effect of target interaction andtopography." Diss., Texas A&M University, 2004. http://hdl.handle.net/1969.1/2770.
Full textAbstract:
The solution of the secondary coupled-vector potential formulation of Maxwell??s equations governing the controlled-source electromagnetic (CSEM) response of an arbitrary, threedimensionalconductivitymodelmust be calculatednumerically.The finite elementmethod is attractive, because it allows the model to be discretized into an unstructured mesh, permitting the specification of realistic irregular conductor geometries, and permitting the mesh to be refined locally, where finer resolution is needed. The calculated results for a series ofsimple test problems, ranging from one-dimensionalscalar differentialequations to three-dimensional coupled vector equations match the known analytic solutions well, with error values several orders of magnitude smaller than the calculated values. The electromagnetic fields of a fully three-dimensional CSEM model, recovered from the potentials using the moving least squares interpolation numerical differentiation algorithm, compares well with published numerical modeling results, particularly when local refinement is applied. Multiple buried conductors in a conductive host interact via mutual induction and current flow through the host due to the dissipation of charge accumulated on the conductor boundary. The effect of this interaction varies with host conductivity, transmitter frequency, and conductor geometry, orientation, and conductivity. For three test models containingtwo highly conductive plate-like targets, oriented in various geometries (parallel, perpendicular, and horizontal), mutual coupling ranges as high as twenty times the total magnetic field. The effect of varying host conductivity is significant, especially at high frequencies. Numerical modeling also shows that the vorticity of the currents density induced in a vertically oriented plate-like conductor rotates from vertical at high frequencies, to horizontal at low frequencies, a phenomenon confirmed by comparison with time domain field data collected in Brazos County, Texas. Furthermore, the effect of the presence of a simple horst on the CSEM response of a homogeneous conductive earth is significant, even when the height of the horst is only a fraction of the skin depth of the model. When the transmitter is placedon topofthe horst, the currents inducedtherein account for nearly all of the total magnetic field of the model, indicating that topography, like mutual coupling must be accounted for when interpreting CSEM data.
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Gautam, Deepthi Riggs Lloyd Stephen. "A robot mounted electromagnetic induction system for identification of a UXO free corridor." Auburn, Ala., 2009. http://hdl.handle.net/10415/1926.
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Domme, Daniel Joseph. "Experimental and Analytical Characterization of a Transducer for Energy Harvesting Through Electromagnetic Induction." Thesis, Virginia Tech, 2008. http://hdl.handle.net/10919/32112.
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Advances in mechatronics have renewed interest in the harvesting and storage of ambient vibration energy. This work documents recent efforts to model a novel electromagnetic transducer design that is intended for use in energy harvesting. The thesis details methods of experimental characterization as well as model validation. Also presented are methods of state space and parametric modelling eforts. In addition, this thesis presents equivalent electrical circuit models with a focus on switched pulse-width-modulated topologies that seek to maximize harvested energy.Master of Science
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Palasagaram, Jithendra N. Riggs Lloyd Stephen. "Efforts towards the design and development of an electromagnetic induction sensor optimized for detection and discrimination of unexploded ordnance." Auburn, Ala., 2006. http://repo.lib.auburn.edu/2006%20Spring/master's/PALASAGARAM_NAGASANJEEVA_44.pdf.
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MacDonald, Kenneth J. "Parallel processing methods applied to two and three dimensional geo-electromagnetic induction modelling." Thesis, University of Edinburgh, 1996. http://hdl.handle.net/1842/11078.
Full textAbstract:
Two existing finite difference algorithms for solving the forward modelling problem of geoelectromagnetic induction have been recoded to take advantage of high performance massively parallel SIMD (single instruction multiple data) computer architectures. Poll's solves the two scalar polarised fields in the two dimensional (2D) problem, and the other from Pu solves for all three components of the magnetic field in three dimensional (3D) structures. Both models apply integral boundary conditions at the top and bottom of the grid to limit total mesh size. The 3D model introduces a thin sheet at the top of the model to describe near surface features. An efficient data parallel algorithm ensures the evaluation of the integrals maintains a high ratio of processor utilisation on the parallel hardware. Data parallel versions of the point Jacobian, Gauss-Seidel and successive overrelaxation iterative solvers have been developed. The latter two require two level black-white ordering, which to equalise the processor load balance, has been implemented in both a horizontally banded and chequer boarded remapping of grid nodes. The 2D model was also developed to form a task farm, whereby the solution for each period is performed on one of a cluster of workstations. These solutions are independent of each other, so are executed simultaneously on however many workstations are available at the time. Modern workstations, coupled with the original 2D Gauss-Jordan solver, are faster than the SIMD computers for all but the largest grid sizes. However, the 3D code certainly benefited from the parallel processing for any but the smallest models. A new automatic meshing algorithm, which stretches a predefined number of grid points over the conductivity structure, has also been developed. In part, this was to control the mesh sizes and hence load balancing on the SIMD computers, but investigations into grid spacing for 2D models show that severely restricting the number of grid points results in a much faster estimated solution.
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Shakya, Nawayandra. "Electromagnetic Modeling of Induction Tool Responses in Isotropic and Anisotropic Layered Earth Formations." Youngstown State University / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=ysu1442437192.
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Liu, Zidong. "High Frequency Inverter Power Stage Design Considerations for Non-Magnetic Materials Induction Cooking." Thesis, Virginia Tech, 2011. http://hdl.handle.net/10919/40674.
Full textAbstract:
Recently induction cookers, which are based on induction heating principle, have become quite popular due to their advantages such as high energy efficiency, safety, cleanliness, and compact size. However, it is widely known that with current technology, induction cookers require the cookware to be made of magnetic materials such as iron and stainless steel. This is why a lot of cookware is labeled â Induction Readyâ on the bottom. The limited choice of â Induction Readyâ cookware causes inconvenience to customers and limits the growing popularity of the induction cooker. Therefore, a novel induction cooker, which can work for non-magnetic material cookware such as aluminum and copper, can be very competitive in the market.
This thesis studies the induction cooking application; briefly introduces its fundamental principle, research background and the motivation of the development of a non-magnetic material induction cooker. Followed by the research motivation, three commonly used inverter topologies, series resonant inverter, parallel resonant inverter, and single-ended resonant inverter, are introduced. A comparative study is made among these three topologies, and the comparative study leads to a conclusion that the series resonant inverter is more suitable for non-magnetic material induction cooking application.
The thesis also presents several major issues about non-magnetic material induction cooking and how to deal with these issues through induction coil design, higher operating frequency and novel control strategy. Because of non-magnetic materialâ s low resistivity and permeability characteristics, it is difficult to be heated and to achieve soft-switching while the coupling between the induction coil and the cooking pan can be easily changed. Later in this thesis, these issues will be discussed in detail and some potential solutions to these issues such as self-sustained oscillating control, optimized induction coil design, proper selection of power semiconductor device, etc.
A 1.5 kW high frequency series resonant inverter with self-sustained oscillating control is prototyped. Experimental results demonstrated successful operation of the resonant inverter under up to 1.5 kW, and the inverterâ s capability to maintain zero-voltage turn-on during wide operating condition is confirmed.
At the end, a summary is given about the research work done in the thesis and future research work is discussed.Master of Science
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McKay, Allan John. "Geoelectric fields and geomagnetically induced currents in the United Kingdom." Thesis, University of Edinburgh, 2004. http://hdl.handle.net/1842/639.
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This thesis investigates geo-electric fields in the United Kingdom with particular regard to Geomagnetically Induced Currents (GIC) in the Scottish Power electricity transmission network (SPTN). The joint spectral characteristics of Scottish Power GIC and Eskdalemuir magnetic observatory data are analysed, and GIC are shown to be coherent with magnetic field variations over the period range 2-1100s. A bi-variate transfer function model of the physical link between magnetic field variations and GIC demonstrates that long-period (>200s) induction makes a first order contribution to the observed GIC at one SPTN site, and dominates the response at another. Thin-sheet modelling at a period of 750s is used to explore the relative influence of three factors on the size and spatial distribution of the calculated electric field: (i) the contrast in conductance between the sea and the land; (ii) variations in conductance due to sea depth; (iii) lateral variations in conductance representative of those in the geographic area occupied by the SPTN. The modelling suggests that a `coast-only' model (i) will over-predict electric field magnitudes in the SPTN region by a factor of 2-5 in comparison with model (iii). Distortion analysis of Magnetotelluric (MT) data at a period of 750s acquired over numerous field campaigns reveal pervasive galvanic distortion of the electric field in the SPTN region. GIC transfer functions of one site are consistently interpreted as proxy MT responses, and it is shown that galvanic distortion of the electric field modifies significantly the GIC amplitude response. A prototype model of the SPTN developed by the British Geological Survey and the Finnish Meteorological Institute is used to calculate GIC. It is shown that neglect of lateral variations of conductivity may lead to false conclusions about the direction of the external electric field that maximises GIC. Time derivatives of the Eskdalemuir horizontal magnetic field are used as an index of GIC activity, and to select events which may have led to large GIC in the time period (1983-2000) prior to the monitoring of GIC by Scottish Power. Backwards-prediction using the GIC transfer functions and observatory magnetic data suggests that GIC at the Scottish Power monitoring sites have amplitudes less than approximately 30A.
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Benavides, Iglesias Alfonso. "Experimental time-domain controlled source electromagnetic induction for highly conductive targets detection and discrimination." Texas A&M University, 2003. http://hdl.handle.net/1969.1/5810.
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The response of geological materials at the scale of meters and the response
of buried targets of different shapes and sizes using controlled-source electromagnetic
induction (CSEM) is investigated. This dissertation focuses on three topics; i) frac-
tal properties on electric conductivity data from near-surface geology and processing
techniques for enhancing man-made target responses, ii) non-linear inversion of spa-
tiotemporal data using continuation method, and iii) classification of CSEM transient
and spatiotemporal data.
In the first topic, apparent conductivity profiles and maps were studied to de-
termine self-affine properties of the geological noise and the effects of man-made con-
ductive metal targets. 2-D Fourier transform and omnidirectional variograms showed
that variations in apparent conductivity exhibit self-affinity, corresponding to frac-
tional Brownian motion. Self-affinity no longer holds when targets are buried in the
near-surface, making feasible the use of spectral methods to determine their pres-
ence. The difference between the geology and target responses can be exploited using
wavelet decomposition. A series of experiments showed that wavelet filtering is able
to separate target responses from the geological background.
In the second topic, a continuation-based inversion method approach is adopted,
based on path-tracking in model space, to solve the non-linear least squares prob-
lem for unexploded ordnance (UXO) data. The model corresponds to a stretched-
exponential decay of eddy currents induced in a magnetic spheroid. The fast inversion of actual field multi-receiver CSEM responses of inert, buried ordnance is also shown.
Software based on the continuation method could be installed within a multi-receiver
CSEM sensor and used for near-real-time UXO decision.
In the third topic, unsupervised self-organizing maps (SOM) were adapted for
data clustering and classification. The use of self-organizing maps (SOM) for central-
loop CSEM transients shows potential capability to perform classification, discrimi-
nating background and non-dangerous items (clutter) data from, for instance, unex-
ploded ordnance. Implementation of a merge SOM algorithm showed that clustering
and classification of spatiotemporal CSEM data is possible. The ability to extract tar-
get signals from a background-contaminated pattern is desired to avoid dealing with
forward models containing subsurface response or to implement processing algorithm
to remove, to some degree, the effects of background response and the target-host
interactions.
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Santhanam, Ramya. "LOCALIZED WOUND HEALING: A MATHEMATICAL MODEL FOR ELECTROMAGNETIC INDUCTION ON COATED NANOFIBER WOUND DRESSINGS." Akron, OH : University of Akron, 2006. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=akron1147883471.
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Thesis (M.S.)--University of Akron, Dept. of Biomedical Engineering, 2006."May, 2006." Title from electronic thesis title page (viewed 12/03/2007) Advisor, S.I. Hariharan; Committee members, Daniel B. Sheffer, Narender P. Reddy; Department Chair, Daniel B. Sheffer; Dean of the College, George K. Haritos; Dean of the Graduate School, George R. Newkome. Includes bibliographical references.
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Amakor, Xystus N. "Using Electromagnetic Induction Sensing to Understand the Dynamics and Interacting Factors Controlling Soil Salinity." DigitalCommons@USU, 2013. https://digitalcommons.usu.edu/etd/1723.
Full textAbstract:
Soil salinization is of great concern in the irrigated arid and semi-arid western United States due to its threat to sustainable agricultural productivity and thus is closely monitored. A widely accepted and traditional standard method for estimating soil salinity is the electrical conductivity of the saturated paste extracts (ECe). However, this method underestimates salinity due to ion pair formation in high ionic strength solution. Numerous studies have recommended the use of an electromagnetic induction (EMI) sensing technique to monitor field-scale soil salinity due to rapidness and non-destructiveness of the sampling. However, because the EMI measurement (ECa) is related to a host of soil properties, calibrating ECa to salinity in a non-homogeneous setting is particularly challenging. The main objective of this study is to understand the dynamics and interacting factors controlling soil salinity using an EMI sensor. Specifically, a correction is made for the underestimation of soil salinity from saturated paste extracts, and a calibration model is developed that is capable of predicting salinity directly from ECa despite the non-homogeneity of potential perturbing factors. A comparison is made of salinity measurement methods based on soil saturated pastes with respect to specific soil management goals. Results show that ion pairing exists even in low ionic strength solution and by diluting the saturated paste extracts to conductivities ≤ 0.03 dS m -1 (ECed), ion pairing is minimized. An improved salinity estimate is obtained by computing total dissolved solids (TDS, in mM) from the ECed values, and then multiplying the TDS by the dilution factor. We also developed a calibration model using quantile regression, which makes no assumption about the distribution of the errors, and which is capable of predicting low range soil salinity (such as that in calcareous soils) from ECa depth-weighted measurements (ECH25ECe). A comparison of ECe, ECed, ECH25ECe, and direct measurement of EC in soil pastes (“ Bureau of Soils Cup ” method, ECcup) across six depths, three texture groups, and the combinations of EC method and depth or texture groups, supports the use of the ECH25ECe method to rapidly and reliably monitor salinity in calcareous soils of arid and semiarid regions.
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Harris, Jane C. "Pieces of a Puzzle: Fitting Electromagnetic Induction into Geophysical Strategies to Produce Enhanced Archaeological Characterisation." Thesis, University of Bradford, 2016. http://hdl.handle.net/10454/15743.
Full textAbstract:
Electromagnetic induction (EM) methods have been utilised in a recent surge of archaeological applications across continental Europe, Ireland and Scandinavia. Development of multi-exploration depth instruments and improvements to instrument stability have improved its reputation as an effective method for mapping archaeological remains. Despite these advances, EM methods are comparatively lacking in rigour when for British sites. Through a structured scheme of experimental analysis and fieldwork, this thesis develops an understanding of the responses of EM instruments over a range of British archaeology, including earthworks, field systems, burials, modern remains, and a Cistercian abbey; the results of which demonstrate its effective over a diversity of environments. The impact of instrument-based issues on the collected measurements was quantified through a scheme of experiments targeting instrument drift, calibration and elevation. Dedicated instrument operation and processing workflows were developed based on the collective field and experimental results, which recommend best practice guidelines for improving the quality and accuracy of collected data. The link between instrument measurements and buried archaeology was further developed through a structured analysis of the EM datasets with complementary earth resistance and magnetic results. The integration of the EM, earth resistance and magnetic datasets was utilised to develop an enhanced archaeological characterisation of subsurface features. While the earth resistance and magnetic methods generally responded to different aspects of the buried archaeology, the EM surveys were able to detect a range of responses evident in the results of the former methods. Therefore, the role of EM methods within this characterisation are shown to “bridge the gap” between the earth resistance and magnetic methods, while providing a comprehensive characterisation of the remains in their own right.
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Parks, Eric M. "Analysis of Electromagnetic and Seismic Geophysical Methods for Investigating Shallow Sub-surface Hydrogeology." BYU ScholarsArchive, 2009. https://scholarsarchive.byu.edu/etd/2007.
Full textAbstract:
An integrated electromagnetic (EM) and seismic geophysical study was performed to evaluate non-invasive approaches to estimate depth to shallow groundwater in arid environments with elevated soil salinity where the installation of piezometers would be impractical or prohibited. Both methods were tested in two study areas (semi-arid and arid respectively), one in Palmyra, Utah, USA near the shore of Utah Lake where groundwater is shallow and unconfined in relatively homogeneous lacustrine sediments. The other area is Carson Slough, Nevada, USA near Ash Meadows National Wildlife Refuge in Amargosa Valley. The area is underlain by valley fill, with generally variable shallow depths to water in an ephemeral braided stream environment. The methods used include frequency domain electromagnetic induction allowing for multiple antenna-receiver spacings. High resolution compressional P-wave seismic profiles using a short (0.305 m) geophone spacing for common depth-point reflection stacking and first arrival modeling were also acquired. Both methods were deployed over several profiles where shallow piezometer control was present. The semi-arid Palmyra site with its simpler geohydrology serves as an independent calibration to be compared to the Carson Slough Site. EM results at both sites show that water surfaces correspond with a drop in conductivity. This is due to elevated concentrations of evaporative salts in the vadose zone immediately above the water table. EM and seismic profiles at the Palmyra site were readily correlated to depth to groundwater in monitoring wells demonstrating that the method is ideal under laterally homogeneous conditions. Interpreting the EM and seismic profiles at Carson Slough was challenging due to the laterally and vertically variable soil types, segmented perched water surfaces, and strong salinity variations. The high-resolution images and models provided by the seismic profiles confirm the simple soil and hydrological structure at the Palmyra site as well as the laterally complex structure at Carson Slough. The EM and seismic results indicate that an integrated geophysical approach is necessary for an area like Carson Slough, where continued leaching of salts combined with braided stream deposition has created a geophysically complex soil and groundwater system.
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Ahmed, Mohammad Faruque. "Simulating and assessing salinisation in the lower Namoi Valley." University of Sydney. Land Water and Crop Sciences, 2001. http://hdl.handle.net/2123/811.
Full textAbstract:
Dryland salinity is increasing in the upper catchments of central and northern New South Wales, Australia. Consequently, salts may be exported downstream, which could adversely affect cotton irrigated-farming systems. In order to assess the potential threat of salinity a simple salt balance model based on progressively saline water (i.e., ECiw 0.4, 1.5, 4.0 and 9.0 dS/m) was used to simulate the potential impact of salinisation due to the farming systems. The study was carried out in the lower Namoi valley of northern New South Wales, Australia. A comparison has been made of the various non-linear techniques (indicator kriging, multiple indicator kriging and disjunctive kriging) to determine an optimal simulation method for the risk assessment. The simulation results indicate that potential salinisation due to application of the water currently used for irrigation (ECiw) is minimal and may not pose any problems to sustainability of irrigated agriculture. The same results were obtained by simulation based on irrigation using slightly more saline water (ECiw 1.4 dS/m). However, simulations based on irrigation using water of even lower quality (ECiw of 4 and 9.0 dS/m), shows potential high salinisation, which will require management inputs for sustainable cropping systems, especially legumes and wheat, which are used extensively in rotation with cotton. Disjunctive kriging was the best simulation method, as it produced fewer misclassifications in comparison with multiple-indicator kriging and indicator kriging. This study thus demonstrates that we can predict the salinity risk due to application of irrigation water of lower quality than that of the current water used. In addition, the results suggest here problems of excessive deep drainage and inefficient use of water might be a problem. The second part of this thesis deals with soil information required at the field scale for management practices particularly in areas where deep drainage is large. Unfortunately, traditional methods of soil inventory at the field level involve the design and adoption of sampling regimes and laboratory analysis that are time-consuming and costly. Because of this more often than not only limited data are collected. In areas where soil salinity is prevalent, detailed quantitative information for determining its cause is required to prescribe management solutions. This part deals with the description of a Mobile Electromagnetic Sensing System (MESS) and its application in an irrigated-cotton field suspected of exhibiting soil salinity. The field is within the study area of part one of this thesis-located about 2 km south west of Wee Waa. The EM38 and EM31 (ECa) data provide information, which was used in deciding where soil sample sites could be located in the field. The ECa data measured by the EM38 instrument was highly correlated with the effective cation exchange capacity. This relationship can be explained by soil mineralogy. Using different soil chemical properties (i.e. ESP and Ca/Mg ratio) a detailed transect study was undertaken to measure soil salinity adjoining the water storage. It is concluded that the most appropriate management option to remediation of the problem would be to excavate the soil directly beneath the storage floor where leakage is suspected. It is recommended that the dam not be enlarged from its current size owing to the unfavourable soil mineralogy (i.e. kaolin/illite) located in the area where it is located.
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Bergman, Kevin, and Erik Amgård. "Wireless Communication Using Energy Harvesting Push Button." Thesis, Linköpings universitet, Elektroniska Kretsar och System, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-129458.
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A disadvantage with battery powered circuits is the fact that the battery sometimes can run out of power. If a button that can generate energy by applying mechanical work to it was applied instead of batteries, is it possible to enable a transmitter to stay active long enough to transmit data which can later by received and decoded? This thesis contains a study, in which how to effectively send data wirelessly between a transmitter and receiver module, without the use of any batteries or external power sources, only an energy harvesting push button is constructed and evaluated. There will also be a theoretical comparison between different transmission formats and which is more suitable for a task such as this.
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Suarez, Freile Daniel A. "Use of Soft Magnetic and Carbon Nanotube Composites in Electromagnetic Cores." University of Cincinnati / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1627661121142792.
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Balan, Anil. "Theoretical and experimental investigations on radial electromagnetic forces in relation to vibration problems of induction machines." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/nq24067.pdf.
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Carsillo, Vincent John. "MONITORING STORMWATER INFILTRATION IN A VACANT LOT COMPARING TIME-LAPSE ELECTROMAGNETIC INDUCTION AND ELECTRICAL RESISTIVITY TOMOGRAPHY." Master's thesis, Temple University Libraries, 2018. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/518905.
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GeologyM.S.
Vacant lots in cities and surrounding urban areas can potentially be used for stormwater management because they are pervious. However, the extent to which vacant lots provide pervious cover to increase infiltration and reduce stormflow is poorly understood. The goal of this study was to develop faster methods for monitoring stormwater infiltration to improve characterization of heterogeneous urban systems. Geophysical techniques are capable of mapping and characterizing subsurface materials, but are often limited by time and sensitivity constraints. In this study, the infiltration characteristics of a vacant lot created by the demolition of a house was characterized using a series of modeling, field and lab experiments. Site characterization under background conditions with an EM Profiler was used to map zones of different fill materials. Three zones were identified in the study site: grass area, driveway area, and a former house area. Transient soil moisture conditions were monitored during irrigation tests using two geophysical methods (electrical resistivity tomography [ERT] and electromagnetic induction [EM]) to evaluate method sensitivity and differences between the three zones. ERT proved more sensitive than EM profiling at detecting changes in the three zones. Soil moisture changes in the driveway area were particularly difficult to detect using EM. The EM Profiler showed a reduction rather than increase in conductivity at the start of irrigation and storms, which was attributed to flushing of high conductivity pore fluids by dilute irrigation or rain water. This explanation was supported using Archie’s Law to model the response of apparent conductivity under highly conductive pore fluid conditions. The EM Profiler was also used under natural precipitation conditions to quickly monitor areas too large for the ERT to reasonably survey. The results suggested that EM instrument drift needs to be corrected to make the method more sensitive. It was difficult to detect differences in hydrologic characterization between areas of the vacant lot using traditional soil point measurements because of the inherent spatial variability. The most useful point measurement was soil moisture loggers. Data from soil moisture loggers was used to parameterize the model; in addition, the soil moisture loggers showed a slow drying period. By combining the EM Profiler method with soil moisture data and applying corrections for drift, some improvement in sensitivity might be achieved. Quantitative characterization of fill material was shown by ERT, which detected more heterogeneous infiltration in the area of the former house than in the grass area.
Temple University--Theses
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Elgwel, Abdulbast Mohamed. "Aspect independent detection and discrimination of concealed metal objects by electromagnetic pulse induction : a modelling approach." Thesis, Manchester Metropolitan University, 2013. http://e-space.mmu.ac.uk/315698/.
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The work presented in this thesis describes the research, modelling and experimentation which were carried out so as to explore the use of electromagnetic pulse induction for the detection of nearby or on-body threat items such as handguns and knives. Commercially available finite difference time domain electromagnetic solver software, Vector Fields, was used to simulate the interaction of a low frequency electromagnetic pulse with different metal objects. The ability to discriminate between objects is based on the lifetime of the induced currents in the object, typically around 100 (μs). Lifetimes are different for a different objects, whether they are weapons or benign objects. For example hand grenades, knives, and handguns are clearly threat objects whereas a wrist watch, mobile phone and keys are considered benign. Electromagnetic pulse Induction (EMI) relies on generating a time-changing but spatially uniform magnetic field, which penetrates and encompasses a concealed metallic object. The temporally changing magnetic field induces eddy currents in the conducting object, which subsequently decay by dissipative (i.e. resistive) losses. These currents decay exponentially with time and exhibit a characteristic time constant (lifetime) which depends only upon the size, shape and material composition of the object, whilst the orientation of the object is irrelevant. This aspect independence of temporal current decay rates forms the basis of a potential object detection and identification system. This thesis investigates the possibility of detecting, resolving and identifying multiple objects if they are close together, for example located on an individual. The mathematical analysis used for the investigation implements the generalised pencil of function (GPOF) method. The GPOF algorithm decomposes the signal into a discrete set of complex frequency components; providing the capability to obtain the time constants from data. It was possible to effectively count and identify multiple metallic objects carried in close proximity providing that the objects do not have very similar time constants. The simulation results, which show that multiple objects can be detected, resolved and identified by means of their time constants even when they are close together, are presented.
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Shi, Yinghui. "Acoustical Performance of Lined Induction Furnace in Electric Field Configuration." University of Dayton / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1627658524197215.
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Krueger, Kyle R. "Model design for algorithmic efficiency in electromagnetic sensing." Diss., Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/50402.
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The objective of the proposed research is to develop structural changes to the design and application of electromagnetic (EM) sensing models to more efficiently and accurately invert EM measurements to extract parameters for applications such as landmine detection. Two different acquisition modalities are addressed in this research: ground-penetrating radar (GPR) and electromagnetic induction (EMI) sensors. The models needed for practical three-dimensional (3D) spatial imaging typically become impractically large, with up to seven dimensions of parameters that need to be extracted. These parameters include, but are not limited to target type, 3D location, and 3D orientation. The new special structures for these models exploit properties such as shift invariance and tensor representation, which can be combined with strategic inversion techniques, including the Fast Fourier Transform and semidefinite programming. The structures dramatically reduce the amount of computation and can eliminate the need to store up to five dimensions of parameters while still accurately estimating them.
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Anele, Amos onyedikachi. "Conception et l'amélioration de la structure de couplage magnétique pour des systèmes de transfert de puissance inductive localisées." Thesis, Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLV038/document.
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Compte tenu du contexte économique du marché des hydrocarbures et les problématiques environnementales, le développement des véhicules électriques (VE) prend de l’ampleur car ils sont considérés comme plus écologiques. Aujourd’hui, les véhicules électriques sont considérés comme une solution favorable pour une énergie plus verte. L'électricité qu'ils consomment peut être générée à partir d'un large éventail de sources qui comprennent les combustibles fossiles, l'énergie nucléaire et les énergies renouvelables. Toutefois, les utilisateurs et les propriétaires de véhicules électriques ont encore des réticences car cela nécessite un stockage d'énergie électrique à bord pour assurer une bonne autonomie.Le système de transfert de puissance par effet inductif (LIPT en anglais) est une nouvelle technologie qui permet le transfert d'énergie électrique par champ magnétique et un système de bobines primaires et secondaires. Le champ magnétique est un champ haute-fréquence à plusieurs dizaines de kilohertz. Par rapport au système de câble conventionnel, le système LIPT est capable de fournir une recharge qui est pratique mais également efficace des véhicules électriques. Cependant, actuellement son principal facteur limitant est la mauvaise performance de sa structure de couplage magnétique (MCS). L’objectif de cette thèse est d'améliorer la performance des systèmes MCS pour les systèmes de LIPT afin de concevoir des systèmes à meilleur rendement.Dans un premier temps, sur la base de modèles mathématiques issus de la littérature, un code Matlab a été mis en œuvre pour calculer l'inductance mutuelle des systèmes de bobines mise en jeu dans le MCS. Puis, le calcul et la validation expérimentale des champs magnétiques entre le primaire et le secondaire a été effectué.Dans un second temps, un modèle d'un système LIPT pour la charge d’une batterie de véhicule électrique est présenté. Sur la base des spécifications techniques d’une Renault ZOE, les résultats obtenus montrent que, en adaptant la fréquence de la bobine primaire et en compensant avec un système série-série de condensateurs, un système à 3 kW et un système à 22 kW peuvent atteindre des performances permettant la recharge d’une Renault Zoe dans de bonnes conditions.Enfin, une analyse par éléments finis (FEA) sous COMSOL est développée pour la conception, le calcul et l’optimisation de systèmes MCS plus complexes de nouveaux LIPT. Les modèles de MCS conçus intègrent des bobines d'air évidées avec des configurations appropriées de noyaux magnétiques (par exemple en ferrite), avec des études également sur des parties couvrantes des bobines primaires et secondaires en acier. Les performances des modèles conçus sont déterminées par les valeurs de l'inductance mutuelle et la tension induite qui sont deux critères d’évaluationsTaking into account high oil prices and environmental awareness, the development of electric vehicles (EVs) is considered as a healthier mode of transportation. Amongst other eco-friendly vehicles, EVs are considered as a favourable solution for a greener energy because the electricity they consume can be generated from a wide range of sources which include fossil fuel, nuclear power and renewable energy. However, users and owners of EVs feel uncomfortable because EVs require sufficient electrical energy battery storage on-board to provide sufficient driving autonomy.Lumped inductive power transfer (LIPT) system is a new technology that allows the transfer of electric power between its air-cored primary and secondary coils via high frequency magnetic fields to a consuming device. Unlike the conventional plug-in system, LIPT system is capable of providing a safe, efficient and convenient overnight recharging of EVs. However, its main limiting factor is the poor performance of its magnetic coupling structure (MCS), which is intended to transfer power efficiently. Thus the problem statement of this thesis is to improve the performance of MCS models for LIPT systems.Firstly, based on a more efficient and relevant mathematical model available in the literature, MATLAB code is implemented to compute the mutual inductance between air-cored filamentary circular (FC) coils. Also, the computation and experimental validation of the magnetic fields between two FC coils are presented.Furthermore, computational models of an IPT system for EV battery charge are presented in this thesis. Based on the technical specifications of Renault ZOE, the results obtained show that by supplying a higher frequency AC voltage to the primary coil of the MCS and compensating the primary and secondary sides of the air-cored coils with series-series capacitors, the 3 kW single-phase and 22 kW three-phase IPT systems modelled using MATLAB/Simulink are capable of delivering the electricity needed to power the Renault ZOE.Finally, in order to recommend a suitable and cost-efficient MCS model that can help transfer electric power more efficiently for the battery charging of EVs and E-bikes, a 3-D finite element analysis (FEA) package called COMSOL multiphysics is used to design, compute and investigate a more complex and realistic MCS model of LIPT systems. The designed MCS models incorporate air-cored coils with proper configuration of magnetic cores (e.g. ferrite), structural steel covering for the bottom part of the primary coil and top part of the secondary coil and lastly, iron plate which serves as a covering for the primary coil installed underground and the chassis or underbody structure of EVs. The performance of the designed models are determined by the values of the mutual inductance and induced voltage obtained from COMSOL
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Abdelrehim, Abdelkerim Omar Ahmed. "Magnetic tensor spectroscopy for humanitarian anti-personnel landmine detection." Thesis, University of Manchester, 2016. https://www.research.manchester.ac.uk/portal/en/theses/magnetic-tensor-spectroscopy-for-humanitarian-antipersonnel-landmine-detection(6a5f7588-1470-408d-86b5-cea6e5151774).html.
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The following abstract is for a thesis submitted to the University of Manchester for the degree of Doctor in Philosophy by Omar AbdelRehim AbdelKerim in 2015.Anti-personnel (AP) mines remain a global problem that affects communities around the world, with 110 million active landmines still present. Landmines are a particularly callous and indiscriminate type of weapon detonating irrespective of presence of an enemy soldier or a child. Their devastating effect on communities has led to their ban through the 1997 Mine Ban Treaty. Current detectors used for mine clearance operations have an impeding weakness that has prompted this research; metal detectors used in humanitarian demining suffer from a high False Alarm Rate (FAR) prompting regular excavation of metallic clutter. The research presented aims to develop a detector capable of discriminating between metallic clutter and mines through the use of the magnetic polarizability dyadic tensor to reduce FARs, increase demining efficiency and improve deminer’s safety. A measurement apparatus was designed and constructed to perform spectroscopic magnetic measurements of small symmetrical metallic objects and produce for the first time unscaled accurate tensor values. The tensors deduced from the measurements were validated against analytical and simulated results and were found to be within 5% of measured tensors. The tensors of minimum metal AP mine surrogates and metallic clutter of symmetrical shape were measured and formed part of a tensor library to be used later by future research. This is in addition to a set of un-circulated US coinage which could be used as a calibration metric and a comparison piece for future work in this area. A detailed description of the coil design and manufacturing process is presented to develop a coil array capable of inverting buried metallic object tensors. The selection criterion was poised to identify an array that was best suited to perform the correct measurements in order to invert to an accurate tensor. The manufactured coil exhibited strong mutual coupling between the receive coils deeming it unfit for the portable detector; however, the findings of the work presented and the selection criterion developed has aided the future design of a suitable coil array. Expected signal levels from minimum metal mine detection were calculated and helped aide in the design of future detectors to ensure suitable SNR performance is achieved. A portable detector has been developed using the sensor head presented within this thesis. Work still lies ahead to achieve the complete detector capable of performing target characterisation and clutter elimination; however, significant advances have been made and are presented throughout this thesis.
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Pritchard, Geoffrey Michael. "Electromagnetic induction in a heterogeneous sphere : a three dimensional inversion for the electrical conductivity of the mantle." Thesis, University of Cambridge, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.620942.
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