Eddy Current

Diffusion tensor MRI (DTI) is now a widely used modality to investigate the fiber tissues in vivo, especially the white matter in brain. An automatic pipeline is described in this paper to conduct a localized voxel-wise multiple-subject group comparison study of DTI. The pipeline consists of 3 steps: 1) Preprocessing, including image format converting, image quality check, eddy-current and motion artifact correction, skull stripping and tensor image estimation, 2) study-specific unbiased DTI atlas computation via affine followed by fluid nonlinear registration and warping of all individual DTI images into the common atlas space to achieve voxel-wise correspondence, 3) voxelwise statistical analysis via heterogeneous linear regression and wild bootstrap technique for correcting for multiple comparisons. This pipeline was applied to process data from a fitness and aging study and preliminary results are presented. The results show that this fully automatic pipeline is suitable for voxel-wise group DTI analysis.

Owing to the growing emergence of the end-of-life electrical and electronic products with complex material structures and an ever-diminishing particle size of the valuable metals involved, development of eddy current separators (ECS) has been targeting selective separation of small non-ferrous metal particles smaller than 5 mm. Separability of various materials smaller than 5 ram, including fine copper wires, has been investigated using ECS with various design concepts. The present research work is divided into two parts, with Part focusing on the rotating type ECS which are today common in practice, and with Part II dedicated to the ECS with novel concepts such as wet ECS technology. In Part I, three rotating belted-drum ECS were employed, which are manufactured by Bakker Magnetics, the Netherlands, Huron Valley Steel Co., US, and Eriez Magnetics, UK respectively. It is found that the belted-drum ECS are effective for separating materials below 5 mm if the magnetic drum rotates in opposite direction to the conveyor belt. The separation principle, particularly the "backward phenomenon" of the rotating type ECS for small particles has been unravelled in the present study. Moreover, separation of AI from the 0-10 mm fraction of electronic scrap has been conducted. The results obtained demonstrate that the belted-drum ECS with appropriate design may be applicable for separation of small aluminum particles from electronic scrap.

We present an analytical solution for the magnetic field, induced eddy currents, and the corresponding losses generated in the rotor of a slotless permanent-magnet (PM) motor. The field excitation is a current sheet placed at the stator interior surface. The solution is based on an analytical solution of the diffusion equation using double Fourier series and in the complex domain. The first and the second Fourier series correspond to the time and space harmonics, respectively. We have analyzed the effect of each time harmonic in detail, and verified the results with FEM software.

An algorithm is presented for the automated analysis of rotating probe multifrequency eddy current data obtained from nuclear power plant steam generator tubes (SGT). The algorithm consists of four steps, namely, a preprocessing stage for conditioning the data, a decision tree based feature extraction stage for identifying relevant features for analysis, a neural network based classification stage for identifying signals from various defect types and benign structures, and finally a blind deconvolution based characterization stage for accurately estimating the size and orientation of the detected defects. This algorithm is optimized to maximize the probability of detection (POD), while keeping the number of false alarms (PFA) at a minimum. Initial results presented in this paper look very promising and demonstrate the effectiveness of the proposed algorithm.

We have modeled the effect of passive copper shielding applied to the outside of an actively shielded, axisymmetric z-gradient coil assembly, with the aim of substantially reducing induced eddy currents in the cryostat inner bore that create acoustic noise. For the purpose of calculation, the cylindrical cryostat inner bore and the passive copper shielding are coaxial and are imagined to be sliced into thin ring sections. Each ring section has a finite thickness and is further divided into several concentric layers. The thin cylindrical sections become elements in an electrical network that includes the actively shielded gradient coil. We calculate eddy currents both for single frequency excitations and for time-dependent excitations by modeling a series of trapezoidal pulses. Our results take into account time dependence, diffusion of eddy currents among cylindrical sections and skin depth effects. Two configurations are analyzed. The first is a thin copper layer wrapped around the outer diameter of the gradient assembly, and the second extends the copper over the ends of the gradient assembly. A 2-mm-thick copper layer around the gradient assembly reduces power deposited in the cryostat inner bore by 13.5 dB for a 1 kHz gradient excitation. Extending the passive shield, for the same 2 mm thickness, to cover the ends of the gradient reduces cryostat inner bore power deposition, by 26.7 dB for the same frequency.

Abstracf-Various magnetic vector potential formulations for the eddy current problem are reviewed. The uniqueness of the vector potential is paid special attention. The aim is to develop a numerically stable finite element scheme which performs well at low and high frequencies, does not require an unduly high number of degrees of freedom, and is capable of treating the case of multiply connected conductors.

The interaction between residual stress and fatigue crack growth rate has been investigated in middle tension and compact tension specimens machined from a variable polarity plasma arc welded aluminium alloy 2024-T3 plate. The specimens were tested at three levels of applied constant stress intensity factor range. Crack closure was continuously monitored using an eddy current transducer and the residual stresses were measured with neutron diffraction. The effect of the residual stresses on the fatigue crack behaviour was modelled for both specimen geometries using two approaches: a crack closure approach where the effective stress intensity factor was computed; and a residual stress approach where the effect of the residual stresses on the stress ratio was considered. Good correlation between the experimental results and the predictions were found for the effective stress intensity factor approach at a high stress intensity factor range whereas the residual stress approach yielded good predictions at low and moderate stress intensity factor ranges . In particular, the residual stresses accelerated the fatigue crack growth rate in the middle tension specimen whereas they decelerated the growth rate in the compact tension sample, demonstrating the importance of accurately evaluating the residual stresses in welded specimens which will be used to produce damage tolerance design data.

This paper investigates the interdependence of hysteresis and eddy-current losses in magnetic cores. Based on the results of a numerical model developed for the analysis, the magnetodynamic loss phenomena are found to be distinctly interdependent. Because of the effects of eddy currents on the flux distribution in the lamination depth, hysteresis and excess losses show a dependence on eddy currents, and hence, on the excitation frequency. Eddy-current and excess losses, on the other hand, are affected by the magnetic characteristics of the material where hysteresis plays the role of a damper. An application of the model to a rotating electrical machine has showed that the interdependence between the losses is quite significant.

Previously, thin plate assumptions have been used to obtain a one-dimensional eddy current model for predicting the stationary, transformer-type losses in magnetic bearings built out of laminated material. Using similar assumptions as in the 1-D eddy current model, rotating losses can be predicted for a laminated heteropolar radial magnetic bearing. The thin plate model of rotating losses yields a hybrid analytical-boundary element model that is computationally inexpensive to implement. Predictions from this model compare favorably to losses experimentally measured in rotor run-down tests.

MRI systems often use magnetic field gradient and shim pulse-shaping networks (pre-emphasis) to correct for magnetic field distortions caused by eddy currents. A pre-emphasis system that uses up to 16 fixed resistor-capacitor (RC) time constants per channel with programmable amplitude coefficients is described. The magnetic fields induced by the pre-emphasis RC time constants serve as a set of basis functions for compensating eddy-current fields induced by the gradient set. The resultant time-varying magnetic field gradient accurately reflects the gradient specified by the pulse programmer. Reductions in eddy-current fields are demonstrated for actively shielded and unshielded gradient sets.

PurposeThe purpose of this paper is to propose a new outer‐rotor permanent‐magnet flux‐switching machine (ORPMFSM) for electric vehicle (EV) in‐wheel propulsion. The paper documents both the design procedure and performance investigation of this novel machine.Design/methodology/approachThe topology and preliminary sizing equations of the ORPMFSM are introduced. The rotor poles are optimized, whilst the machine losses are particularly investigated, using 2‐D finite element analysis (FEA).FindingsAn ORPMFSM, with 12 stator poles and 22 rotor poles, is most suitable for the proposed EV application. The analytical sizing equations are quite efficient with a sufficient accuracy for the preliminary design. The optimal rotor pole width from the FEA results is nearly 1.3 times the original value which was proposed in early literatures. The efficiency of the proposed machine under rated load is slightly low, as a result of significant eddy current losses in the permanent magnets. The losses ...

Aliased and dealiased numerical simulations of a turbulent channel flow are performed using spectral and finite difference methods. The problem of aliasing errors in spectral simulations Analytical and numerical studies show that aliasing errors are more of turbulent flows has been discussed in the literature [4-7]. destructive for spectral and high-order finite-difference calculations It has been demonstrated that, depending on the form of than for low-order finite-difference simulations. Numerical errors the nonlinear terms [5] in the Navier-Stokes equations, have different effects for different forms of the nonlinear terms in aliased spectral simulations can become unstable, exhibit the Navier-Stokes equations. For divergence and convective forms, spectral methods are energy-conserving only if dealiasing is per-decay, or give reasonable results. Zang [5] performed sevformed. For skew-symmetric and rotational forms, both spectral eral spectral simulations of transition and turbulence in and finite-difference methods are energy-conserving even in the incompressible flow and reported that, without dealiasing, presence of aliasing errors. It is shown that discrepancies between the simulations with convective and divergence forms of the results of dealiased spectral and standard nondialiased finitethe nonlinear terms were numerically unstable, whereas difference methods are due to both aliasing and truncation errors with the latter being the leading source of differences. The relative the computations with the rotational form produced inacimportance of aliasing and truncation errors as compared to subgrid curate results. The aliasing errors associated with the rotascale model terms in large eddy simulations is analyzed and distional form were reported to be even more damaging in cussed. For low-order finite-difference simulations, truncation ersimulations of transition. The poor behavior of the rotarors can exceed the magnitude of the subgrid scale term. ᮊ 1997 tional form was also reported earlier by Horiuti [8] who Academic Press carried out large eddy simulations of turbulent channel flow. No dealiasing was performed in that study. Horiuti found that turbulence decayed when the rotational form 310

Eddy-current couplings are becoming popular devices for speed and torque control. Efficiency of these couplings depends on the excitation level; therefore, the routes and density of induced currents affect it significantly. This paper focuses on the design of a squirrel cage-type coupling disk, which forces eddy currents to flow perpendicular to both magnetic field lines and the axis of rotation. Lorentz force and transmitted torque are consequently optimized. The investigation is performed both numerically and experimentally, with results being presented for variable air gaps and speeds. A comparison between plain and slotted disk conductors, tested under identical setups , demonstrates the effect of the proposed design on torque throughput and efficiency. In addition to this, the influence of number and size of slots and the effect of filling slots with iron are studied by parametric finite-element modeling verified by experiments.

Rotor eddy-current loss is usually significant in high-speed permanent magnet brushless dc (PM BLDC) motors. On the other hand, the rotor is usually protected with a nonmagnetic retaining sleeve. The influence of the conductivity of the retaining sleeve on the rotor eddy-current loss is analyzed in this paper. Furthermore, utility of a conductive copper shield between the sleeve and magnets is demonstrated. Although eddy current is induced in the copper shield, causing additional loss, its magnetic field can smooth the varying field in the rotor and reduce the overall eddy-current loss dramatically. The relationship between the thickness of copper shield and the rotor eddy-current loss is also examined.

In this communication we propose a 3D numerical model In which the magnetic field and electric circuit equations in the absence of eddy currents are solved simultaneously. To consider the magnetic equations we use a magnetic vector potentlal formulation with the gauge condition (A.w=O) which permHs to reduce the number of unknowns. To take into account the magnetic and electric non-linearities, the Newton-Raphson algorithm has been used. Two applications have been considered an Iron core coil fed by sinusoidal voltage through a diode and a current transformer. In the last example the results obtained from the simulation are compared with experimental ones.

The principle of corrosion measurement/monitoring by means of tangential film-based radiography is already known. Most of this experience, however, is limited to qualitative determination of internal defects. The ability to reliably measure remaining wall thickness in pipes has not yet been established. The International Atomic Energy Agency has organized a Co-ordinated Research Project bringing together twelve Member States to study “validation of protocols for corrosion and deposits determination in large diameter pipes by radiography”. The general scope of the project covers radiographic measurement of corrosion and deposits in straight and bent large diameter (>160mm) pipes made of carbon or stainless steel corroded/eroded on the outer or inner surfaces with or without insulation. It is expected to define the limits of detection for each radiation source using the tangential method and to explore the double wall technique beyond this limit. Introduction: The International Ato...

Municipal solid waste incineration (MSWI) bottom ash contains economically significant levels of silver and gold. Bottom ashes from incinerators at Amsterdam and Ludwigshafen were sampled, processed, and analyzed to determine the composition, size, and mass distribution of the precious metals. In order to establish accurate statistics of the gold particles, a sample of heavy non-ferrous metals produced from 15 tons of wet processed Amsterdam ash was analyzed by a new technology called magnetic density separation (MDS). Amsterdam’s bottom ash contains approximately 10 ppm of silver and 0.4 ppm of gold, which was found in particulate form in all size fractions below 20 mm. The sample from Ludwigshafen was too small to give accurate values on the gold content, but the silver content was found to be identical to the value measured for the Amsterdam ash. Precious metal value in particles smaller than 2 mm seems to derive mainly from waste of electrical and electronic equipment (WEEE), wh...

The magnetic flux density has two components, B from of the induced eddy c u r r e n t s d u e t o a magnet moving above a aluminium s t r i p conductor, have been measured f o r t h e magnet centrally positioned over the strip and t h e magnet displaced towards the edge of t h e s t r i p . -0 the inductor and B from t h e eddy currents, i.e. -w B = B + B --0 -w (2) Constant current contours are plotted for the two cases a t d i f f e r e n t v e l o c i t i e s . The r e s u l t s o b t a i n e d i n d i c a t e Using t h e m a g n e t i c v e c t o r p o t e n t i a l i , where that with the magnet displaced towards the edge of t h e aluminium t r a c k t h e eddy c u r r e n t d i s t r i b u t i o n a s a function of v e l o c i t y i s no longer compatible with the semi i n f i n i t e s h e e t p a t t e r n . -A = & + & ( 3 ) and V x i = E (4) one obtains: V x (--w + -= 0 which has a s o l u t i o n 1 J 1 INTRODUCTION a t (5) In the electrodynamic system of magnetic levitation t h e l i f t and drag forces are produced by t h e i n t e ra c t i o n between a superconducting (essentially permanent) L J = --(-0 +-w) magnet on t h e v e h i c l e moving above a conducting track, e.g. aluminium s t r i p . I n t h e Warwick s p l i t t r a c k By t a k i n g t h e l i n e i n t e g r a l around the p l a t e it can be d e s i g n , b o t h v e r t i c a l l i f t and l a t e r a l guidance forces shown t h a t J and A are connected by a r e produced by t h e eddy c u r r e n t d i s t r i b u t i o n i n t h e inner edges of t h e aluminium. To study the eddy curr-J = -e n t p a t t e r n a n e x p e r i m e n t a l r i g i s being used whereby a a A A u-w a t ( 6 ) -w -w 2 a~ = 2 a A -w pod (% -)z= +dl2 g(z -w ) z = -dl2 (7) rectangular shaped, permanent magnet (rare earth cobalt) i s r o t a t e d a t d i f f e r e n t known v e l o c i t i e s above a f i x e d Combining ( 6 ) and (7) l e a d s t o s t r i p of aluminium track. The induced eddy c u r r e n t s a r e measured i n b o t h t h e t r a n s v e r s e and l o n g i t u d i n a l d i r e c t i o n s by scanning the voltages generated on a s e r i e s of metal probes embedded i n t h e aluminium. Measurements have been taken as a function o f t h e veloc i t y and t h e l a t e r a l d i s p l a c e m e n t of t h e magnet and contour plots of t h e c u r r e n t d i s t r i b u t i o n have been obtained. Good agreement with theoretical calculations i s obtained for the case of a magnet c e n t r a l l y p o s i t i o ned over the aluminium s t r i p , i . e . t h e c u r r e n t s form two loops of o p p o s i t e c i r c u l a t i o n below the magnet, while a t higher speeds an essentially image loop i s formed d i r e c t l y below t h e magnet with a second wake l o o p t r a i ling behind. However, a s t h e magnet i s displaced towards the edge of t h e t r a c k t h e eddy c u r r e n t d i s t r i bu t i o n as a function of v e l o c i t y i s no longer compatible

A new approach for 3-D eddy current computation using volume integral equations is presented. The formulation is derived directly from Maxwell's equations and it enables solution of problems with conducting, nonconducting and magnetic subregions. It is shown how the discrete problem is formed based on Whitney forms. Adopting Whitney's elements, consistency between the continuous and discrete formulations is achieved, and the numerical problem can be formed without difficulty. A brief discussion of the discretisation in the case of multiply connected regions is also given. Some test results are shown in order to ascertain the correctness of the formulation.

The frequency dependence of the magnetic energy losses in sintered Mn-Zn ferrites is predicted from the quasistatic regime to the megahertz range. The predicting model is based on the appraisal of the contributions by domain wall ͑dw͒ displacements and magnetization rotations and the related relaxation-resonant-type dissipation mechanisms. Eddy currents are demonstrated to play little to negligible role. The frequency dependence of the dw generated losses is calculated from knowledge of the quasistatic losses, whereas the contribution by rotations is obtained via the Landau-Lifshitz-Gilbert equation, assuming distributed anisotropy fields. The model excellently applies to the frequency response of commercial ferrites.

In this paper, an experimental investigation, an analytical analysis and a numerical model of a typical four-point bending test on a honeycomb sandwich panel are proposed. The honeycomb core is modelled as a single solid layer of equivalent material properties. Analytical and numerical (finite element) homogenization approaches are used to compute the effective properties of the honeycomb core. A general kinematic model (unified formulation) has been adopted and used for the modelling of honeycomb sandwich panel submitted to the bending test. A comparative study of major classes of representative theories has been considered. Qualitative and quantitative assessments of displacement, stress have been presented and discussed.

The interest in eddy current dampers is increasing especially in aeronautic and automotive industry. Such devices seem to be a valid alternative to conventional fluid film and viscoelastc dampers. Even if several papers have been published on this topic, an electromechanical model taking into account both the resistance and the inductance of the conductor is still lacking. The aim of the present paper is to model the electromagnetic interaction of an eddy current device operating as a damper or as a coupler and to validate it by means of experimental tests performed at steady state and vibrating about a fixed position. The study is based on the computation of the damping torque starting from the basic principles. The analytical models are developed using the bond graph formalism that allows to obtain purely mechanical analogs of the electromechanical system. The main results are the identification of eddy current damper dynamic model and the definition of a set of "conversion rules" allowing to readily obtain the mechanical impedance from the torque to slip speed characteristic and vice versa. The experimental results confirm the band limited effect of the damping, which cannot be neglected for practical applications. The effect can be exploited in eddy current couplers to filter higher order disturbances.

We present a model for the motion of particles in an eddy current separation process. The model describes the action of the transient magnetic field of the separator by a first-order linear differential equation for the particle magnetic moment. From the model, qualitative conclusions can be drawn regarding the effects of particle size, shape and conductivity on the particle trajectory. It is also possible to solve the equations of motion for particles of simple shapes by numerical integration. The results of such simulations are compared with experimental data. The aim of the model is to improve the understanding of the behaviour of small particles in eddy current processes in order to optimize separator design and operation.

Manganese-substituted nickel–zinc ferrites have been investigated as power core materials for applications in switched-mode-power supplies. High frequency operation of these power supplies requires high performance cores with low power losses. The main contributors to the power loss are eddy current loss, hysteresis loss and residual loss. The ferrites have been synthesized by the citrate precursor technique and their electromagnetic properties such as resistivity, permeability, saturation magnetization and Curie temperature studied. A power loss of 500 mW/cc could be obtained at a frequency of 500 kHz, flux density of 50 mT and temperature 100 °C.

Measurement of flow in liquid metal systems exhibit unusual problems because of the severe operating environments like high operating temperatures and the chemical reactivity of most liquid metals. The liquid metal flowmeters should have the capacity to withstand high gamma radiation levels and rapid thermal transients. The commonly used flowmeters in liquid metal systems are permanent magnet Flowmeter, direct current electromagnet Flowmeter and alternating current electromagnet flowmeter. In Alternating current electromagnet Flowmeter there are three types namely transverse field Flowmeter, Eddy Current Flowmeter and E-Core Flowmeter. The subject of analysis is the Eddy current Flowmeter. Eddy currents are generated when a moving conductor experiences changes in the magnetic field generated by a stationary object, as well as when a stationary conductor encounters a varying magnetic field. A flowmeter which works on this principle is the Eddy Current Flowmeter. This paper gives a thorough survey on eddy current flowmeter, its construction, simulation results and its performance under various test conditions in different organization

The paper presents a new possibility of obtaining lower space harmonic content for the fractional-slot, toothconcentrated windings by interspersing the phase windings. By using multiple layer windings it is possible to reduce or even to cancel some space sub-harmonics having as final result lower eddy current losses induced by the armature reaction in the iron structure of the rotor. The general method of multiplying the winding and relatively shifting by one (or more) slots is presented in the paper. The application of the method is developed for the general case of the windings having Z=2p±1 where, instead of double layers winding, the partial three or even four layers winding is obtained. The example of application is given for 15 slots, 14 poles, three phase concentrated windings which is presented and analyzed as primitive windings.

This paper presents a digital signal processing system specially designed for eddy currents non-destructive testing. This new system has a Field Programmable Gate Array based processing core, several communication interfaces, data conversion and analog devices to interface the probes. Communication with personal computers is ensured by Ethernet 10/100 and USB 2.0 High Speed interfaces. The proposed architecture enables to set several combinations of peripherals cards to generate or acquire probe signals. Also, the new system allows the digital generation and analysis of the probe signals through multiple digital signal processing algorithms. Two different peripheral cards have been developed to meet the needs for the new IOnic concept of eddy currents probe. The IOnic acquisition card is composed by a programmable gain amplifier and a high speed analog to digital converter. The current stimulus generation is achieved with a digital to analog converter and a high output current transconductance amplifier. Together, the two peripherals are able to operate the probe from 10 kHz up to 10 MHz. An additional peripheral card to interface stepper motors was designed and used for sensor positioning.

Surface mountable eddy current sensors are a revolutionary new concept in nondestructive inspection. These eddy current sensors can be mounted, like a strain gage, at critical locations for detection of crack initiation and monitoring of crack growth. This can be accomplished on a fatigue test article, as well as on in-service aircraft or other structures (patents pending). The mountable periodic field eddy current sensors, described in this paper, can be used as a replacement for standard eddy-current sensors without introducing new requirements. This is not the case with other proposed health monitoring sensors. For critical structures, substantially reduced inspection costs and life extension is possible with permanently mounted eddy current sensors. This is particularly true for difficult-to-access locations that require surface preparation (e.g., sealant or insulation removal) and disassembly when conventional eddy current testing is performed.

The electromagnetic braking using eddy current was studied, focused on two series of aluminium as the brake disc which are Al6061 and Al7075. This paper presents the comparison for both series in a few varied parameters related to eddy current braking such as air-gap, number of turns and brake disc thickness. Optical tachometer has been used along with PULSE analyzer to capture the speed (rpm) and time (s). The findings shows that the smaller the air-gap, the larger of electromagnet turns and the thicker disc thickness is, will generate higher braking torque to stop the rotational motion of disc brake and give great performance for eddy current braking. Those parameters that been evaluated also addressed a potential on expanding this knowledge to develop an electromagnetic braking system to replace the conventional braking system.

The three-dimensional (3-D) eddy-current problem, described in spherical coordinates, is studied both analytically and numerically. Since the vector field equation is not separable in the spherical coordinate system, the second-order vector potential (SOVP) formulation is used to treat the problem by reducing it to the solution of the scalar field equation. While the analytical solution is expressed in terms of

An eddy current braking experiment was conducted to study the behaviour of three different materials to be used as brake disc which are aluminium, copper and zink. The experiment also aimed to see the effects of increasing the current induced into electromagnet which produce drag force that will slow down the motion. Results from the experiment have been recorded using optical tachometer connected to PULSE analyzer which captured the speed (RPM) and time (s). A few graph been presented in this paper to show the best material to be used as the brake disc for electromagnetic braking system using eddy current project. This preliminary result will leads to a deeper research in field of electromagnetic braking and its potential application.

This paper is concerned with a new modeling technique for the effective eddy current damper and vibration suppression of a beam using the eddy current damper. The eddy current damper consists of the permanent magnets and the conducting sheet. The relative motion between the magnets and the conducting sheet produces eddy currents thus resulting in the electromagnetic force, which turns out to be the damping force thus suppressing vibrations. The important advantage of the proposed eddy current damper is that it does not require any electronic devices and external power supplies. In the present study, the theoretical model for the eddy current damper is derived using the electromagnetic theory combined with the image method. The theoretical model enables us to estimate the damping augmented to the host structure as well as develop a design tool for the eddy current damper. It is found from the comparison with the experimental results that the theoretical model can predict the damping characteristics and the dynamic behavior of the structure. The theoretical and experimental results also showed that the vibration of the beam can be successfully suppressed by means of the eddy current damper.

This paper introduces both stray magnetic-field and thermal analyses of electric submersible pump (ESP) motors and cables under normal and abnormal operating conditions. These abnormal operating conditions include running the electric submersible pump motor under imbalance and single-phasing. Moreover, both concentric and eccentric electric submersible pump oil well models with flat and round cables were investigated. Experimental tests were conducted on a reduced-scale electric submersible pump motor. In addition, theoretical simulations were performed using a finite-element based software package for a reduced-scale electric submersible pump motor, and a full-scale electric submersible pump motor and its power cable of flat and round types. Compared to the cases of running the motor under balanced or unbalanced conditions, the single-phasing operation of eccentric wells gives the highest localized magnetic-flux and eddy current densities, hence the possibility of localized corrosion increases. It has been found that there is a strong correlation between the eddy-current thermal effect and the severe localized corrosion of the electric submersible pump system. Therefore, it is highly recommended to use round power cables and not to operate the electric submersible pump system under single phasing conditions.

So far, the non-destructive measurement of ferrous metals such as cast iron by the eddy current method is not available on the market. This is due to the difficulties arising from highly variable magnetic properties of ferrous metals. We have recently implemented a system to overcome this obstacle using a multi-parameter computing method and an external biasing magnetic field. The nondestructive measurement of the electrical conductivity opens the way for other important applications such as the measurement of the residual thickness of steel or steel alloy products.

Many techniques today allow non-destructive testing (NDT) or non-destructive evaluation (NDT) of materials. The use of these techniques is particularly developed in the nuclear, gas, oil and aeronautical industries. They reveal the presence of defects, such as cracks, inclusions, corrosion, etc.
Among the most widely used methods is the technique of eddy current non-destructive testing (NDF-CF), the latter consists in evaluating the state of health of a part by measuring the variation of the impedance of inductive sensors.
This work synthesizes the study and simulation by the 3D finite element method of an eddy current fault detection device. The system is simulated under the Ansys-Maxwell environment, it has an air core coil placed over a conductive part representing a cracked support of a helicopter. In order to realize the crack detection, the coil scans the target and the signals are collected in terms of the variation of the impedance of the coil. The results obtained can constitute an important database for the opposite problem.
Key words: Nondestructive testing, cracks, eddy currents, 𝑇⃗ -ᴪ formulation, finite element method

Performance of rolls in an Integrated Steel Plant like Tata Steel affects many plant performance measures i.e. mills down time (which affects plant productivity), rejection of rolled products, roll dressing time, consumption of rolls / ton of steel rolled etc. In order to ensure the supply of the rolls without harmful flaws, NDT techniques, particularly Ultrasonic and Eddy Current, were developed and implemented on the shop floor to improve the plant performance by reducing their failure in the mill. Indefinite Chilled Cast Iron Double Poured Work Rolls of finishing stands, High Chrome Iron as well as Chrome Steel Work Rolls of early finishing and roughing stand were evaluated for their shell / core disbond as well as surface cracks using these techniques. High Speed Steel rolls under trial in the finishing stand F2 were also evaluated for their surface cracks using an eddy current inspection method developed at R&D Division of Tata Steel..

We develop a finite-element analysis (FEA) model to describe transient and static operation of gas-exchange valves. Such valves, directly controlled by solenoids, are a promising method for enhancing automotive engine efficiency. The FEA model is validated by experimental testing on an actual automotive prototype valve. We show that a nonlinear lumped-parameter model that uses FEA results also closely matches experimental data. The lumped-parameter model is suitable for optimization of design and can be readily used for closed-loop simulation. We present a simplified lumped-parameter model to facilitate controller design. Finally, we compare a dynamic open-loop simulation with experimental results.