scholarly journals Induced Eddy Currents in Simple Conductive Geometries: Mathematical Formalism Describes the Excitation of Electrical Eddy Currents in a Time-Varying Magnetic Field

2018 ◽  
Vol 60 (1) ◽  
pp. 81-88 ◽  
Author(s):  
James R. Nagel
Keyword(s):  
Magnetic Field ◽  
Eddy Currents ◽  
Mathematical Formalism ◽  
Time Varying

Improved Concept and Model of Eddy Current Damper

2005 ◽  
Vol 128 (3) ◽  
pp. 294-302 ◽  
Author(s):  
Henry A. Sodano ◽  
Jae-Sung Bae ◽  
Daniel J. Inman ◽  
W. Keith Belvin
Keyword(s):  
Magnetic Field ◽  
Theoretical Model ◽  
Eddy Current ◽  
Eddy Currents ◽  
Opposite Polarity ◽  
Image Method ◽  
Time Varying ◽  
Transverse Beam ◽  
Eddy Current Damper ◽  
Improved Model

When a conductive material experiences a time-varying magnetic field, eddy currents are generated in the conductor. These eddy currents circulate such that they generate a magnetic field of their own, however the field generated is of opposite polarity, causing a repulsive force. The time-varying magnetic field needed to produce such currents can be induced either by movement of the conductor in the field or by changing the strength or position of the source of the magnetic field. In the case of a dynamic system the conductor is moving relative to the magnetic source, thus generating eddy currents that will dissipate into heat due to the resistivity of the conductor. This process of the generation and dissipation of eddy current causes the system to function as a viscous damper. In a previous study, the concept and theoretical model was developed for one eddy current damping system that was shown to be effective in the suppression of transverse beam vibrations. The mathematical model developed to predict the amount of damping induced on the structure was shown to be accurate when the magnet was far from the beam but was less accurate for the case that the gap between the magnet and beam was small. In the present study, an improved theoretical model of the previously developed system will be formulated using the image method, thus allowing the eddy current density to be more accurately computed. In addition to the development of an improved model, an improved concept of the eddy current damper configuration is developed, modeled, and tested. The new damper configuration adds significantly more damping to the structure than the previously implemented design and has the capability to critically damp the beam’s first bending mode. The eddy current damper is a noncontacting system, thus allowing it to be easily applied and able to add significant damping to the structure without changing dynamic response. Furthermore, the previous model and the improved model will be applied to the new damper design and the enhanced accuracy of this new theoretical model will be proven.

A CONDUCTING SPHERE IN A TIME VARYING MAGNETIC FIELD

Geophysics ◽  
1951 ◽  
Vol 16 (4) ◽  
pp. 666-672 ◽  
Author(s):  
James R. Wait
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Eddy Currents ◽  
Transient Behavior ◽  
Step Function ◽  
Conducting Medium ◽  
Time Varying ◽  
Geophysical Prospecting ◽  
Conducting Sphere

The secondary magnetic fields are evaluated for the case of a conducting sphere in a relatively poorly conducting medium under the influence of a time varying magnetic field. The sinusoidal and step function responses are both considered. The responses so calculated are thought to be useful in a geophysical prospecting method which utilizes the transient behavior of induced eddy currents in a highly conducting ore zone.

Internal Organizational Measurement for Control of Magnetorheological Fluid Properties

2006 ◽  
Vol 129 (4) ◽  
pp. 423-428 ◽  
Author(s):  
John R. Lloyd ◽  
Miquel O. Hayesmichel ◽  
Clark J. Radcliffe
Keyword(s):  
Magnetic Field ◽  
Physical Properties ◽  
High Sensitivity ◽  
Time Varying ◽  
Measurable Effect ◽  
Mr Fluid ◽  
Fluid State ◽  
Mr Fluids ◽  
Fluid Properties ◽  
Field Excitation

Magnetorheological (MR) fluids change their physical properties when subjected to a magnetic field. As this change occurs, the specific values of the physical properties are a function of the fluid’s time-varying organization state. This results in a nonlinear, hysteretic, time-varying fluid property response to direct magnetic field excitation. Permeability, resistivity and permittivity changes of MR fluid were investigated and their suitability to indicate the organizational state of the fluid, and thus other transport properties, was determined. High sensitivity of permittivity and resistivity to particle organization and applied field was studied experimentally. The measurable effect of these material properties can be used to implement an MR fluid state sensor.

A Novel Approach to Accumulate Superparamagnetic Particles in Aqueous Environment Using Time-Varying Magnetic Field

2020 ◽  
Vol 67 (6) ◽  
pp. 1558-1564 ◽  
Author(s):  
Ya-Li Liu ◽  
Jing-Jie Chen ◽  
Fiaz Ahmad ◽  
Tuo-Di Zhang ◽  
Wei-Hong Guo ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Aqueous Environment ◽  
Time Varying ◽  
Superparamagnetic Particles ◽  
Novel Approach

PHOTON-ASSISTED TRANSPORT CHARACTERISTICS THROUGH QUANTUM DOT COUPLED TO SUPERCONDUCTING RESERVOIRS

NANO ◽  
2006 ◽  
Vol 01 (03) ◽  
pp. 259-264 ◽  
Author(s):  
A. S. ATALLAH ◽  
A. H. PHILLIPS ◽  
A. F. AMIN ◽  
M. A. SEMARY
Keyword(s):  
Magnetic Field ◽  
Numerical Calculation ◽  
Quantum Dot ◽  
Resonant Tunneling ◽  
Andreev Reflection ◽  
Point Contact ◽  
Quantum Point Contact ◽  
Time Varying ◽  
Quantum Point ◽  
Tunneling Behavior

The influence of time-varying fields on the transport through a mesoscopic device has been investigated. This mesoscopic device is modeled as a quantum dot coupled to superconducting reservoirs via quantum point contact. The effect of a magnetic field and the Andreev reflection process were taken into account. The conductance was deduced by using Landuaer–Buttiker equation. A numerical calculation has been performed that shows a resonant tunneling behavior. Such investigation is important for fabricating photoelectron mesoscopic devices.

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