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Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 53 for “"eddy currents"”.
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Caracterização por ensaios magnéticos não destrutivos de aços HP provenientes de fornos de reforma
… that modify their magnetic properties. The eddy currents technique and a permanent magnetic sensor were used for the HP steel magnetic characterization. The resulting signals, both from eddy currents and sensor were plotted on a contrast map with the purpose of showing a thorough …
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Development of Novel Eddy Current Dampers for the Suppression of Structural Vibrations
… damping. Magnetic dampers function through the eddy currents that are generated in a conductive material that experiences a time varying magnetic field. However, following the generation of these currents, the internal resistance of the conductor causes them to dissipate into heat. Because a …
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The response of the Red Sea to a strong wind jet near the Tokar Gap in summer
… it is shown that an intense dipolar eddy spins up in less than seven days in response to the wind jet. The eddy pair has a horizontal scale of 140 km. Maximum ocean surface velocities can reach 1 m/s and eddy currents extend at least 200 m into the water column. The eddy currents …
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The response of the Red Sea to a strong wind jet near the Tokar Gap in summer
… it is shown that an intense dipolar eddy spins up in less than seven days in response to the wind jet. The eddy pair has a horizontal scale of 140 km. Maximum ocean surface velocities can reach 1 m/s and eddy currents extend at least 200 m into the water column. The eddy currents …
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Simulation and control of a stepping motor
… direct input-outout measurements. The effects of eddy currents, saturation, hysteresis, drive circuit characteristics and non-linear torque displacement characteristics are considered and methods of determining transfer functions, which take account of these effects, are offered. The static torque …
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Computer aided analysis and design of a single phase tubular induction actuator
… induction actuator (TLIA) which makes use of eddy currents to produce useful thrust. Compared with normal DC or AC solenoids, it possesses advantages of long thrust, large starting force and low starting current. Unlike linear motors, it is much simpler in structure and cheaper.<br/><br/>In …
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Attitude Dynamics of Debris Resulting From Upper Stage Fragmentation in Low Earth Orbit
… of conducting body in a magnetic field generates eddy currents which create a torque in the opposite direction of the change in the magnetic flux and thus reduce the rotational rate of the body. The eddy currents that generate torques are described by Maxwell's equations. and the generalized Ohm's …
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AC loss in MgB2-based fully superconducting electric machines
… produces considerable loss due to hysteresis, eddy currents, and coupling. For this reason, many present designs for such machines are partially superconducting, meaning that the dc field components are superconducting while the ac armature coils are normal copper conductors. A fully …
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Enhanced Magnetic Flux Leakage Analysis of the Distribution of Flux and The Effects of Velocity of Mild Steel Plates
… between the plate and the excitation system, eddy currents are induced opposing the applied magnetic field distorting its profile. This has an adverse effect on MFL inspection by altering signal responses thus limiting achievable inspection velocities. An investigation of velocities ranging …
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Modulation Technique for Magneto -Optic Imaging of Weak Magnetic Fields With Rare-Earth Iron Garnet Films
… of aging aircraft as well as imaging of eddy currents in superconductors, but so far has been limited to imaging fields in the millitesla range. The bismuth-doped rare-earth iron garnet films studied here exhibit hysteresis, which can be overcome by a kilohertz-frequency modulation …
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Modeling and optimization of permanent magnetic motors
… Equations are applied to the analysis of eddy currents and torque measurements are made to verify the theoretical predictions. Simplified motor models are discovered which yield symbolic solutions for optimal motor parameters as a function of mass. The Monte Carlo method is applied to the …
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Advances in Magnetic Resonance Phase‐Contrast Velocity Mapping
… imperfections resulting from uncompensated eddy currents are studied using dynamic magnetic field monitoring demonstrating that mechanical vibrations can have a large impact on flow quantification. Approaches for background phase offset correction based on field monitoring data are …
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Contactless voltage and current estimation using signal processing and machine learning
… sensor developed to estimate the line currents and line-to-line voltages of a multi-phase cable in the presence of significant external disturbances. The current estimates are derived from an array of point magnetic-field measurements processed by a linear least-square-error estimator. …
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Enhanced next generation alternator
… conditions is studied. It is found that rotor eddy currents limit the rate at which the machine can be de-excited to terminate the transient overvoltage. Models for the de-excitation process are developed based on experimental measurements, and new field control circuits are proposed that …
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Design and control methods for high-accuracy variable reluctance actuators
… actuator model that incorporates the effects of eddy currents. The reticle stage in a scanning lithography machine requires high accelerations combined with sub-nanometer position accuracy. Reluctance actuators are capable of providing high force densities (force per moving mass) and lower power …
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Axisymmetric equilibrium and stability analysis in Alcator C-Mod, including effects of current profile, measurement noise and power supply saturation
… plasmas is unstable on the time scale of the eddy currents in the axisymmetric conducting structures. In the absence of feedback control, the plasma would drift vertically and quench on the wall, a situation known as Vertical Displacement Event (VDE), with serious consequences for machine …
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Analysis and design of ferrite cores for eddy current-killed oscillator inductive proximity sensors
… operation is dependent on the generation of eddy currents within the metal target, the range at which the target can be detected is a direct function of how optimally the magnetic flux is cut by the target. In this study the target is a circular disk, just as is used in industry for …
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Electrochemical Synthesis of Soft Magnetic Alloys and Laminates for High Frequency Field Application
… and serves as the resistive barriers mitigating eddy current flow between the magnetic layers. Compared to single-layer or bulk magnetic alloy counterparts, the synthesized laminates exhibit at least 50% higher resistivity. High-frequency characterization reveals that the lamination process …
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High resolution 3D diffusion tensor imaging for delineating neuronal architectures
… phase error, magnetic susceptibility and eddy currents. Simulation, phantom, and in vivo results are included to verify the performance of the proposed methods.
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Finite element analysis of 3D electric machine problems
… as multiple materials, complicated geometry, eddy currents, and saturation. In this thesis, we adopt the finite element method, one of the most powerful numerical schemes, to analyze electric machine problems. Starting from Maxwell’s equations, we derive the governing equations using both …
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