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Articoli di riviste sul tema "Small-loop electromagnetic induction method"
1
Swidinsky, Andrei, e Chester J. Weiss. "On coincident loop transient electromagnetic induction logging". GEOPHYSICS 82, n. 4 (1 luglio 2017): E211—E220. http://dx.doi.org/10.1190/geo2017-0134.1.
Testo completoAbstract (sommario):
Coincident loop transient induction wireline logging is examined as the borehole analog of the well-known land and airborne time-domain electromagnetic (EM) method. The concept of whole-space late-time apparent resistivity is modified from the half-space version commonly used in land and airborne geophysics and applied to the coincident loop voltages produced from various formation, borehole, and invasion models. Given typical tool diameters, off-time measurements with such an instrument must be made on the order of nanoseconds to microseconds — much more rapidly than for surface methods. Departure curves of the apparent resistivity for thin beds, calculated using an algorithm developed to model the transient response of a loop in a multilayered earth, indicate that the depth of investigation scales with the bed thickness. Modeled resistivity logs are comparable in accuracy and resolution with standard frequency-domain focused induction logs. However, if measurement times are longer than a few microseconds, the thicknesses of conductors can be overestimated, whereas resistors are underestimated. Thin-bed resolution characteristics are explained by visualizing snapshots of the EM fields in the formation, where a conductor traps the electric field while two current maxima are produced in the shoulder beds surrounding a resistor. Radial profiling is studied using a concentric cylinder earth model. Results found that true formation resistivity can be determined in the presence of either oil- or water-based mud, although in the latter case, measurements must be taken several orders of magnitude later in time. The ability to determine true formation resistivity is governed by the degree that the EM field heals after being distorted by borehole fluid and invasion, a process visualized and particularly evident in the case of conductive water-based mud.
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Klose, Tim, Julien Guillemoteau, François-Xavier Simon e Jens Tronicke. "Toward subsurface magnetic permeability imaging with electromagnetic induction sensors: Sensitivity computation and reconstruction of measured data". GEOPHYSICS 83, n. 5 (1 settembre 2018): E335—E345. http://dx.doi.org/10.1190/geo2017-0827.1.
Testo completoAbstract (sommario):
In near-surface geophysics, small portable loop-loop electromagnetic induction (EMI) sensors using harmonic sources with a constant and rather small frequency are increasingly used to investigate the electrical properties of the subsurface. For such sensors, the influence of electrical conductivity and magnetic permeability on the EMI response is well-understood. Typically, data analysis focuses on reconstructing an electrical conductivity model by inverting the out-of-phase response. However, in a variety of near-surface applications, magnetic permeability (or susceptibility) models derived from the in-phase (IP) response may provide important additional information. In view of developing a fast 3D inversion procedure of the IP response for a dense grid of measurement points, we first analyze the 3D sensitivity functions associated with a homogeneous permeable half-space. Then, we compare synthetic data computed using a linear forward-modeling method based on these sensitivity functions with synthetic data computed using full nonlinear forward-modeling methods. The results indicate the correctness and applicability of our linear forward-modeling approach. Furthermore, we determine the advantages of converting IP data into apparent permeability, which, for example, allows us to extend the applicability of the linear forward-modeling method to high-magnetic environments. Finally, we compute synthetic data with the linear theory for a model consisting of a controlled magnetic target and compare the results with field data collected with a four-configuration loop-loop EMI sensor. With this field-scale experiment, we determine that our linear forward-modeling approach can reproduce measured data with sufficiently small error, and, thus, it represents the basis for developing efficient inversion approaches.
3
Guillemoteau, Julien, Niels Bøie Christensen, Bo Holm Jacobsen e Jens Tronicke. "Fast 3D multichannel deconvolution of electromagnetic induction loop-loop apparent conductivity data sets acquired at low induction numbers". GEOPHYSICS 82, n. 6 (1 novembre 2017): E357—E369. http://dx.doi.org/10.1190/geo2016-0518.1.
Testo completoAbstract (sommario):
Electromagnetic induction (EMI) sensors using sufficiently low-frequency harmonic sources and sufficiently small loop separations operate in the low-induction-number (LIN) domain for a relatively wide range of background conductivity. These systems are used in diverse near-surface investigations including applications from soil sciences, hydrology, and archaeology. The special case of portable multiconfiguration EMI sensors operating at frequencies [Formula: see text] offers the possibility of using a fast linear deconvolution method to interpret multichannel data sets in three dimensions. Here, we have developed a fast 3D inversion/deconvolution method regularized with 3D smoothness constraints and formulated in the hybrid spectral-spatial domain. Compared with other linear approaches, the spectral-spatial domain formulation significantly reduces the computational cost of the processing and opens the door for real-time 3D interpretation of large data sets consisting of more than 100,000 data points. First, we test our proposed algorithm on synthetic data sets computed with the full Maxwell theory. Then, we apply our method to a real four-configuration EMI data set acquired to map the thickness of peat layers embedded in a sandy environment. For the synthetic and the field example, we compared our result with the result obtained using a standard point-by-point 1D nonlinear inversion approach. This comparison demonstrates that the proposed methodology provides superior lateral resolution compared with the 1D nonlinear inversion, at the same time significantly reducing the computational cost of the processing.
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Guillemoteau, Julien, Pascal Sailhac, Charles Boulanger e Jérémie Trules. "Inversion of ground constant offset loop-loop electromagnetic data for a large range of induction numbers". GEOPHYSICS 80, n. 1 (1 gennaio 2015): E11—E21. http://dx.doi.org/10.1190/geo2014-0005.1.
Testo completoAbstract (sommario):
Ground loop-loop electromagnetic surveys are often conducted to fulfill the low-induction-number condition. To image the distribution of electric conductivity inside the ground, it is then necessary to collect a multioffset data set. We considered that less time-consuming constant offset measurements can also reach this objective. This can be achieved by performing multifrequency soundings, which are commonly performed for the airborne electromagnetic method. Ground multifrequency soundings have to be interpreted carefully because they contain high-induction-number data. These data are interpreted in two steps. First, the in-phase and out-of-phase data are converted into robust apparent conductivities valid for all the induction numbers. Second, the apparent conductivity data are inverted in 1D and 2D to obtain the true distribution of the ground conductivity. For the inversion, we used a general half-space Jacobian for the apparent conductivity valid for all the induction numbers. This method was applied and validated on synthetic data computed with the full Maxwell theory. The method was then applied on field data acquired in the test site of Provins, in the Parisian basin, France. The result revealed good agreement with borehole and geologic information, demonstrating the applicability of our method.
5
Guillemoteau, Julien, François-Xavier Simon, Guillaume Hulin, Bertrand Dousteyssier, Marion Dacko e Jens Tronicke. "3-D imaging of subsurface magnetic permeability/susceptibility with portable frequency domain electromagnetic sensors for near surface exploration". Geophysical Journal International 219, n. 3 (26 agosto 2019): 1773–85. http://dx.doi.org/10.1093/gji/ggz382.
Testo completoAbstract (sommario):
SUMMARY The in-phase response collected by portable loop–loop electromagnetic induction (EMI) sensors operating at low and moderate induction numbers (≤1) is typically used for sensing the magnetic permeability (or susceptibility) of the subsurface. This is due to the fact that the in-phase response contains a small induction fraction and a preponderant induced magnetization fraction. The magnetization fraction follows the magneto-static equations similarly to the magnetic method but with an active magnetic source. The use of an active source offers the possibility to collect data with several loop–loop configurations, which illuminate the subsurface with different sensitivity patterns. Such multiconfiguration soundings thereby allows the imaging of subsurface magnetic permeability/susceptibility variations through an inversion procedure. This method is not affected by the remnant magnetization and theoretically overcomes the classical depth ambiguity generally encountered with passive geomagnetic data. To invert multiconfiguration in-phase data sets, we propose a novel methodology based on a full-grid 3-D multichannel deconvolution (MCD) procedure. This method allows us to invert large data sets (e.g. consisting of more than a hundred thousand of data points) for a dense voxel-based 3-D model of magnetic susceptibility subject to smoothness constraints. In this study, we first present and discuss synthetic examples of our imaging procedure, which aim at simulating realistic conditions. Finally, we demonstrate the applicability of our method to field data collected across an archaeological site in Auvergne (France) to image the foundations of a Gallo-Roman villa built with basalt rock material. Our synthetic and field data examples demonstrate the potential of the proposed inversion procedure offering new and complementary ways to interpret data sets collected with modern EMI instruments.
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Kozhevnikov, N. O., e E. Yu Antonov. "Aftereffects in the Transient Electromagnetic Method: Magnetic Viscosity". Russian Geology and Geophysics 63, n. 3 (1 marzo 2022): 312–20. http://dx.doi.org/10.2113/rgg20204306.
Testo completoAbstract (sommario):
Abstract One of the aftereffects inherent in geological materials is magnetic viscosity. This phenomenon consists in the time lag of changes in magnetic characteristics in relation to changes in the external magnetic field. In rocks, magnetic viscosity is mainly associated with magnetization of superparamagnetic particles. In the transient electromagnetic method, magnetic viscosity is manifested as a slowly decreasing voltage induced in a receiving loop, or, in some cases, as a nonmonotone transient voltage response. Eddy currents and viscous magnetization establish and decay independently; therefore, the induction transient response measured with a fixed-geometry TEM array gives no way of finding the vertical distribution of magnetic viscosity. In order to find it, geometric soundings are needed. At later times, the voltage induced in the receiving loop due to the magnetization decay is vastly larger than that induced by the eddy currents. Because of this, magnetic viscosity contribution to the total transient response limits the sounding depth of the transient electromagnetic method.
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Sasaki, Yutaka, Jung-Ho Kim e Seong-Jun Cho. "Multidimensional inversion of loop-loop frequency-domain EM data for resistivity and magnetic susceptibility". GEOPHYSICS 75, n. 6 (novembre 2010): F213—F223. http://dx.doi.org/10.1190/1.3503652.
Testo completoAbstract (sommario):
Electromagnetic (EM) induction measurements are affected by resistivity and magnetic susceptibility. Thus, inverting EM data for resistivity alone can give misleading models if susceptible effects are strong. An inversion algorithm is presented to simultaneously recover multidimensional distributions of resistivity and susceptibility from various types of loop-loop frequency-domain EM data. The algorithm adopts a staggered-grid finite-difference method for the 3D forward solutions and computes the sensitivities with respect to resistivity and susceptibility from the forward solutions using the reciprocity principle. The algorithm is tested on synthetic data sets from ground-based small-loop, airborne, and Slingram EM surveys. It is shown that the simultaneous inversion of the small-loop EM data collected at a singleheight is unstable and likely to produce unreliable susceptibility models because the effect of susceptibility is nearly independent of the frequency. However, if the data are obtained for multiple heights or different loop configurations, simultaneous inversion can produce more reliable susceptibility and resistivity models even if the data are contaminated by offset errors. It is also shown that although the simultaneous inversion of airborne EM data is relatively stable, adding data obtained at different heights helps to increase the reliability of the resistivity and susceptibility models. Among the loop-loop EM methods discussed here, the Slingram method is relatively insensitive to susceptibility anomalies and thus cannot be used to recover the susceptibility distribution via inversion even if the data are obtained using different loop configurations.
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Guillemoteau, Julien, e Jens Tronicke. "Evaluation of a rapid hybrid spectral-spatial domain 3D forward-modeling approach for loop-loop electromagnetic induction quadrature data acquired in low-induction-number environments". GEOPHYSICS 81, n. 6 (novembre 2016): E447—E458. http://dx.doi.org/10.1190/geo2015-0584.1.
Testo completoAbstract (sommario):
When exploring subsurface environments using electromagnetic (EM) induction (EMI) tools, approximate forward-modeling methods based on a homogeneous half-space kernel have been extensively evaluated in the past. For large-scale exploration methods, such as magnetotellurics, marine EM, airborne EM, transient EM, and large offset loop-loop harmonic EM, such forward-modeling approaches are limited because the kernel depends strongly on the subsurface distribution of electrical conductivity. However, the response of small portable EMI loop-loop sensors applied in a low-induction number (LIN) context are known to be more linearly related to the true distribution of electrical conductivity. Thus, data collected using such sensors are more adapted to an approximate forward-modeling with a conductivity-independent kernel. We have evaluated the bias of such an approximate modeling for the case of portable multiconfiguration system measurements in 1D, 2D, and 3D contexts. Our result shows that the approximate approach tends to underestimate the conductivity of more conductive targets but is able to reproduce the right structural information. Compared with previous algorithms presented in the literature, we solved the approximate forward-modeling problem in the hybrid spectral-spatial domain to speed up the computation. Considering the level of accuracy in structural modeling as well as the computational efficiency of our hybrid spectral-spatial approach, we conclude that this method is especially suitable for near-surface, large-scale mapping applications in LIN environments as typically encountered in soil sciences and archaeological studies. For such applications, our approach can be implemented in rapid multichannel deconvolution procedures.
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Kamm, Jochen, Michael Becken e Laust B. Pedersen. "Inversion of slingram electromagnetic induction data using a Born approximation". GEOPHYSICS 78, n. 4 (1 luglio 2013): E201—E212. http://dx.doi.org/10.1190/geo2012-0484.1.
Testo completoAbstract (sommario):
We present an efficient approximate inversion scheme for near-surface loop-loop EM induction data (slingram) that can be applied to obtain 2D or 3D models on a normal desktop computer. Our approach is derived from a volume integral equation formulation with an arbitrarily conductive homogeneous half-space as a background model. The measurements are not required to fulfill the low induction number condition (low frequency and conductivity). The high efficiency of the method is achieved by invoking the Born approximation around a half-space background. The Born approximation renders the forward operator linear. The choice of a homogeneous half-space yields closed form expressions for the required electromagnetic normal fields. It also yields a translationally invariant forward operator, i.e., a highly redundant Jacobian. In connection with the application of a matrix-free conjugate gradient method, this allows for very low memory requirements during the inversion, even in three dimensions. As a consequence of the Born approximation, strong conductive deviations from the background model are underestimated. Highly resistive anomalies are in principle overestimated, but at the same time difficult to resolve with induction methods. In the case of extreme contrasts, our forward model may fail in simultaneously explaining all the data collected. We applied the method to EM34 data from a profile that has been extensively studied with other electromagnetic methods and compare the results. Then, we invert three conductivity maps from the same area in a 3D inversion.
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Thiesson, Julien, Alain Tabbagh, Michel Dabas e Antoine Chevalier. "Characterization of buried cables and pipes using electromagnetic induction loop-loop frequency-domain devices". GEOPHYSICS 83, n. 1 (1 gennaio 2018): E1—E10. http://dx.doi.org/10.1190/geo2016-0476.1.
Testo completoAbstract (sommario):
The detection and characterization of buried cables and metal pipes has become a key component of field surveys carried out prior to excavation work on construction sites. The very high conductivity and magnetic permeability contrast between any buried cables/pipes compared with the soil makes electromagnetic induction (EMI) instruments very useful for their detection. We have developed a seminumerical method that can be used to model the responses of this type of target. A straight horizontal conductor is equivalent to a series of magnetic dipoles, the magnitude of which can be determined in the spectral domain and then converted back into the spatial domain through the use of an inverse fast Fourier transform. Simulations and case studies allow to establish rules of thumb for the estimation of (1) the nature of the metal: the in-phase response of magnetic cables is of the opposite sign from the conducting ones, (2) the sensitivity to the target characteristic: the influence of the cable/pipe diameter is greater than that of the metal properties, and (3) the depth of the cables. The simulations also underline the role of the coil configuration: Vertical coplanar and perpendicular responses allow a more precise location of the cable/pipe, whereas the horizontal coplanar response is less dependent on the orientation. As ground truth, a known electric cable buried at a depth of 0.5 and 0.002 m in diameter is determined at 0.56 m. The first field test is related to the detection of a buried military cable from World War I, between 2.5 and 3 m below the original ground level. The second field test is related to the detection of a water pipe 0.35 m deep. The modeling technique can be applied to all EMI prospecting methods, and thus it opens the way to the correction of the disturbances generated by cables and pipes.
Tesi sul tema "Small-loop electromagnetic induction method"
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Cavalcante, Fraga Luis Henrique. "Caractérisation des sols pollués via des méthodes géophysiques : couplage entre le diagnostic conventionnel et les méthodes géophysiques pour estimer la distribution spatiale des polluants à l’aide du formalisme géostatistique". Electronic Thesis or Diss., Sorbonne université, 2019. http://www.theses.fr/2019SORUS645.
Testo completoAbstract (sommario):
La caractérisation spatiale de sources de pollution est un enjeu majeur pour la réhabilitation de sites pollués. Les analyses géochimiques d’échantillons sont coûteuses et onéreuses en temps et ne permet qu’une vision ponctuelle des sites. Ces travaux ont évalué la méthode de cartographie électromagnétique (EMI) pour imager les propriétés physiques indirectes du sous-sol afin de (1) définir des protocoles de mesures géophysiques adaptés (2) d’exploiter les mesures spatialisées (géophysiques et géochimiques) pour l'estimation des volumes de sols pollués aux hydrocarbures grâce au formalisme géostatistique. Les résultats sur le site de Poitiers, localisé en contexte péri-urbain, ont mis en évidence la sensibilité de la méthode EMI pour déterminer la géométrie d'une couche de remblais. La stratégie finale appliquée sur le site de Rouen, fortement pollué aux hydrocarbures et situé en milieu urbain, a été modifiée avec une cartographie EMI exhaustive, des panneaux électriques, une prospection au géoradar et des mesures sur échantillons. L’analyse statistique multivariable a indiqué une corrélation globale entre les teneurs en hydrocarbures et les conductivités électriques apparentes mesurées par la méthode EMI. L’hétérogénéité des remblais, les aménagements et un aquifère discontinu ont fortement perturbé les mesures EMI. Malgré la diminution de la variance de l’erreur d’estimation lorsque les données géophysiques ont été intégrées dans les modèles géostatistiques, les corrélations linéaires restent encore faibles et limitées par la représentativité des sites. Un protocole de mesures géophysiques a été conçu et a montré son potentiel pour la caractérisation de sites polluésThe spatial characterization of pollution sources is a key step for estimating the costs of the rehabilitation of contaminated sites. Geochemical sampling is costly and time-consuming and only allows punctual information about contamination levels. This PhD work evaluated the electromagnetic mapping method (EMI) for imaging the physical properties of the subsoil to (1) define geophysical measurement protocols and (2) exploit spatialized geophysical and geochemical data for a better estimation of hydrocarbon-polluted soil volumes through geostatistical formalism. The results at the Poitiers’ site, located in a peri-urban context with an unknown backfill coverage, highlighted the sensitivity of the EMI method for determining the geometry of the backfill layer. The new geophysical measurement strategy applied at the Rouen’s site, which is heavily polluted with hydrocarbons and located in an urban environment, has been modified with exhaustive EMI mapping, electrical resistivity and polarization tomography, ground penetrating radar and physical measurements at sample scale. The multivariate statistical analysis indicated an overall correlation between the hydrocarbon levels and the apparent electrical conductivities measured by the EMI method. Nevertheless, the heterogeneity of the urban fill, surface facilities and a discontinuous aquifer have severely disrupted EMI measurements. Despite the decrease in the variance of estimation error when geophysical data have been integrated into geostatistical models, linear correlations are still weak. A novel geophysical measurement protocol has been designed and demonstrated its potential for assessing contaminated sites
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Patier, Laurent. "Etude de techniques de calculs multi-domaines appliqués à la compatibilité électromagnétique". Phd thesis, Université Blaise Pascal - Clermont-Ferrand II, 2010. http://tel.archives-ouvertes.fr/tel-00834164.
Testo completoAbstract (sommario):
Le contexte d'étude est celui de la Compatibilité ÉlectroMagnétique (CEM). L'objectif de la CEM est, comme son nom l'indique, d'assurer la compatibilité entre une source de perturbation électromagnétique et un système électronique victime. Or, la prédiction de ces niveaux de perturbation ne peut pas s'effectuer à l'aide d'un simple calcul analytique, en raison de la géométrie qui est généralement complexe pour le système que l'on étudie, tel que le champ à l'intérieur d'un cockpit d'avion par exemple. En conséquence, nous sommes contraints d'employer des méthodes numériques, dans le but de prédire ce niveau de couplage entre les sources et les victimes. Parmi les nombreuses méthodes numériques existantes à ce jour, les méthodes Multi-Domaines (MD) sont très prisées. En effet, elles offrent la liberté aux utilisateurs de choisir la méthode numérique la plus adaptée, en fonction de la zone géométrique à calculer. Au sein de ces méthodes MD, la " Domain Decomposition Method " (DDM) présente l'avantage supplémentaire de découpler chacun de ces domaines. En conséquence, la DDM est particulièrement intéressante, vis-à-vis des méthodes concurrentes, en particulier sur l'aspect du coût numérique. Pour preuve, l'ONERA continue de développer cette méthode qui ne cesse de montrer son efficacité depuis plusieurs années, notamment pour le domaine des Surfaces Équivalentes Radar (SER) et des antennes. L'objectif de l'étude est de tirer profit des avantages de cette méthode pour des problématiques de CEM. Jusqu'à maintenant, de nombreuses applications de CEM, traitées par le code DDM, fournissaient des résultats fortement bruités. Même pour des problématiques électromagnétiques très simples, des problèmes subsistaient, sans explication convaincante. Ceci justifie cette étude. Le but de cette thèse est de pouvoir appliquer ce formalisme DDM à des problématiques de CEM. Dans cette optique, nous avons été amenés à redéfinir un certain nombre de conventions, qui interviennent au sein de la DDM. Par ailleurs, nous avons développé un modèle spécifique pour les ouvertures, qui sont des voies de couplage privilégiées par les ondes, à l'intérieur des cavités que représentent les blindages. Comme les ouvertures sont, en pratique, de petites dimensions devant la longueur d'onde, on s'est intéressé à un modèle quasi-statique. Nous proposons alors un modèle, qui a été implémenté, puis validé. Suite à ce modèle, nous avons développé une méthode originale, basée sur un calcul en deux étapes, permettant de ne plus discrétiser le support des ouvertures dans les calculs 3D.
Capitoli di libri sul tema "Small-loop electromagnetic induction method"
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He, Dongfeng. "Corrosion Evaluation of Steel Rebar Using Electromagnetic Induction Method". In Studies in Applied Electromagnetics and Mechanics. IOS Press, 2020. http://dx.doi.org/10.3233/saem200024.
Testo completoAbstract (sommario):
Corrosion of steel reinforcing bar (rebar) reduces the strength capacity of concrete, and also causes the crack of concrete due the volume increase of the corrosion products. Detection of corrosion at its early stage is important for the safety evaluation and repairment of the concrete structures. An electromagnetic induction method was developed to evaluate the corrosion of steel rebar. By measuring the electromagnetic response of steel rebar, it was possible to judge the corrosion of steel rebar in concrete. A small compact system, suitable for field experiments was also developed.
Atti di convegni sul tema "Small-loop electromagnetic induction method"
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Zhao, Haisen, Weifu Lu, Xiaofang Liu, Xueshen Cui e Yingli Luo. "A Design Method for Non-Skewed Small and Medium Cage Induction Motors". In 2012 Sixth International Conference on Electromagnetic Field Problems and Applications (ICEF). IEEE, 2012. http://dx.doi.org/10.1109/icef.2012.6310351.
Testo completo
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Kim, Hee Reyoung. "The Design of a Small Annular Linear Induction EM Pump for the Transportation of Liquid Sodium in the SFR". In 2013 21st International Conference on Nuclear Engineering. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/icone21-16162.
Testo completoAbstract (sommario):
The linear annular induction electromagnetic (EM) pump was designed for the purpose of transporting the electrically conducting liquid sodium that is used as a coolant in the Sodium cooled Fast Reactor (SFR) in the high temperature of 550 °C. The EM pump was designed by using an equivalent circuit method which is commonly employed to the design of the induction machines. The mathematical equations on the developing pressure and efficiency was found out by using Laithewaite’s standard design formula. The main geometrical parameters for the design were a pump core length, a diameter of the pump and an annular gap size. The dominant electromagnetic variables were the input frequency, magnetic pole pitch and number, and coil turns. Especially, it was shown that the developing pressure and efficiency were maximized at the range of the low frequency less than 60 Hz of the commercial frequency. Also, the size of an annular gap was suitably selected considering the hydraulic frictional loss at the narrow annular channel. The P-Q characteristic was theoretically predicted according to the change of the input current, voltage and power. The functional and structural components of the pump consisted of the material compatible with the high temperature and chemical reactivity of the liquid sodium. The designed pump was predicted to have the nominal flowrate of 10 L/min and the developing pressure of 4 bar.
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Lee, Kok-Meng, Chun-Yeon Lin e Min Li. "A Continuous-Field Actuation Method for Transducing Optical Color Images to Magnetic/Eddy-Current Patterns". In ASME 2015 Dynamic Systems and Control Conference. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/dscc2015-9958.
Testo completoAbstract (sommario):
Motivated by two applications (retinal prosthesis and nondestructive damage detection), this research develops a new actuator utilizing magnetic/electric fields as media to enable open-loop induction control of a relatively high-resolution eddy-current pattern on an electrically conductive surface with a relatively small number of electromagnets (EMs). The actuator referred to here as a magnetic/eddy-current (M/EC) continuous field scanner transduces an image into an M/EC pattern induced by a two-dimensional EM array. Unlike traditional digital stimulation devices where the spatial resolution is defined by discrete spacing between two adjacent electrodes, the continuous-field scanner accurately controls the synthetized M/EC fields between adjacent EMs. Along with a detailed presentation of an analytical model and its inverse solutions to enable the continuous-field scanning, this paper presents a numerical study to investigate the effects of key design parameters, and some preliminary experimental results to validate the concept feasibility of the proposed method.
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Muñoz, Hiram Martinez. "Analysis of Errors in Simulation Modeling". In HT2021. ASM International, 2021. http://dx.doi.org/10.31399/asm.cp.ht2021exabp0053.
Testo completoAbstract (sommario):
Abstract Nowadays, the use of technologies to increase productivity, reduce time, as well as reduce the possibilities of errors, has become indispensable. All processes have opportunities for improvement, and this can be done based on calculations that with the support of computational systems can be reduced considerably in time. In the heat treatment industry and more specifically in the electromagnetic induction heat treatment industry is no exception. Today we have numerous tools to optimize the design process of inductors used in heat treatment of metals. These tools can show us, in a virtual way, the results that we can obtain before having to manufacture the inductors, all this based on FEA (Finite Elements Analysis) simulations that performing calculations considering physical parameters approximate us to what we would have as a result. Computer based simulation programs for induction heating and resulting metallurgy are extremely useful in developing tooling and process for induction heating. Induction hardening simulation brings elements of inductor design, steel properties such as time-temperature-transformation curves, both thermal and magnetic properties at various temperatures and cooling rates based on the phase of the quench media on cooling. A common method in place hardening (static hardening) knows as single shot hardening. In this process, the inductor is designed with a top and bottom half loop connected by heating rails. The length of heating is determined by the length of the rails and percentage height of the width of the half loops. Accurately predicting the length of the heating pattern in this 3D modeling approach is computationally a heavy load on the modeling pre-requisites. Commonly the inductor is modeled and then tested with the actual results showing a different length than what was predicted. It is important to consider that like any system, these simulation tools are not infallible and have several factors that can affect the accuracy of the simulation results. This paper reaches into the analysis of why the predicted length may differ prom the test results discussing what factors constitute the largest variance from the predicted outcome. Inductor design and the reliance on set up will be discussed.
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Zhou, Pu, Yue Zhang, Zhen Zhen, Qiang Wang e Hai-jun Feng. "Study on Vibration Characteristics of Induction Motor Under Load Considering Saturation of Magnetic Circuit". In 2017 25th International Conference on Nuclear Engineering. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/icone25-66807.
Testo completoAbstract (sommario):
The variation law of motor vibration with load under saturation of magnetic circuit is one of the focus of motor vibration research. T-type equivalent circuit method is shown to be a suitable engineering analysis way. In this paper, the variation of magnetic flux density under saturation state was analyzed by using a small induction motor, and a physical model of magnetic saturation and motor vibration was established by the way of T-shaped equivalent circuit. Based on the physical model, the vibration mechanism of the motor under the saturated magnetic circuit was analyzed and the motor vibration simulation with different load conditions was carried out by the finite element method. Finally, a vibration test rig for motor under load was built and the simulation results were verified by experiments. The results show that when the motor load is less than the rated load, the amplitudes of the electromagnetic force in the middle and high frequency band change little. When the load is close to or higher than the rated value, the harmonic components of electromagnetic force in the middle and high frequency bands increase, and the amplitudes gradually increases due to the saturation of the magnetic circuit. Therefore, in the low-noise motor design, motor torque performance and vibration noise performance should be considered to optimize the saturation control of the magnetic circuit.
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Masanori Ishii, Yozo Shimada e Daisuke Nakajima. "Reference method for small circular loop antennas in the MF and HF bands". In 2008 Conference on Precision Electromagnetic Measurements (CPEM 2008). IEEE, 2008. http://dx.doi.org/10.1109/cpem.2008.4574880.
Testo completo
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Harm, Martin, Lukas Oppermann e Achim Enders. "CVNA calibration method for electrically small loop antennas from 9 kHz to 30 MHz". In 2017 International Symposium on Electromagnetic Compatibility (EMC EUROPE). IEEE, 2017. http://dx.doi.org/10.1109/emceurope.2017.8094689.
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Masanori Ishii e Yozo Shimada. "Calibration method for small circular loop antennas using a standard loop antenna and vector network analyzer in low-frequency band". In 2008 International Symposium on Electromagnetic Compatibility - EMC Europe. IEEE, 2008. http://dx.doi.org/10.1109/emceurope.2008.4786877.
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Ishii, Masanori, e Koji Komiyama. "A Measurement Method for the Antenna Factor of Small Loop Antenna by Measuring the Input Impedance". In 2004 Conference on Precision Electromagnetic Measurements. IEEE, 2004. http://dx.doi.org/10.1109/cpem.2004.305450.
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Park, Junsik, Jingook Kim, Jongsung Lee e Byongsu Seol. "Efficient calculation of ESD inductive coupling on a conductor loop using PEEC method". In 2014 IEEE International Symposium on Electromagnetic Compatibility - EMC 2014. IEEE, 2014. http://dx.doi.org/10.1109/isemc.2014.6899034.
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