Global ETD Search
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 26 for “"rotating magnetic field"”.
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A Study of Solidification With a Rotating Magnetic Field
We then simulate the experiments using the numerical model. The numerical model predicts macrosegregation effects similar to those observed in the experiments. The temperature traces obtained from experiments and predicted by the numerical calculations also agree very well. We extend the numerical …
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Effects of demagnetizing factors on transient motion of ferrofluid in a uniform rotating magnetic field
… a ferrofluid-filled container subjected to a rotating uniform magnetic field are experimentally studied. There are two prevailing theories: spin diffusion theory and flow due to non-uniformities in magnetic field within the ferrofluid due to nonuniform demagnetizing factors. This research …
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Magnetic fluid flow phenomena in DC and rotating magnetic fields
An investigation of magnetic fluid experiments and analysis is presented in three parts: a study of magnetic field induced torques in magnetorheological fluids, a characterization and quantitative measurement of properties relating to the transition of a ferrofluid drop from a continuous phase into …
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On the dynamics of magnetic fluids in magnetic resonance imaging
The hydrodynamics of magnetic fluids, often termed ferrofluids, has been an active area of research since the mid 1960s. However, it is only in the past twenty years that these fluids have begun to be used in magnetic resonance imaging (MRI) where they have found application as contrast agents, …
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Ferrofluid dynamics in a Hele-Shaw cell simultaneously stressed by DC and rotating magnetic fields
… experiments have been repeated to evaluate magnetic fluid behavior in DC, AC and rotating magnetic fields. Understanding these behaviors are essential to the ferrohydrodynamic applications of ferrofluids in biomedicine. Careful measurements in Hele-Shaw cells with simultaneous perpendicular …
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Non-intrusive load monitoring for existing water and natural gas metering infrastructure
… This thesis presents an improved model for the rotating magnetic field produced by positive displacement water meters, new methods and non-contact hardware for non-intrusively extracting flow from these and bellows-and-diaphragm natural gas meters, and signal processing techniques for …
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Ferrofluid spin-up flows from uniform and non-uniform rotating magnetic fields
… in a cylindrical container is subjected to a rotating azimuthally directed magnetic field, the fluid "spins up" into an almost rigid-body rotation where ferrofluid nanoparticles have both a linear and an angular "spin" velocity. Flow observations are often limited to the ferrofluid free …
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Einfluss von Strömungen auf die Entwicklung des Mikrogefüges bei der gerichteten Erstarrung von Al-Si- und Al-Si-Mg-Legierungen
The effect of magnetically controlled convective conditions on the microstructure formation in cast Al-alloys is investigated. A technical Al-7wt.%Si-0.6wt.%Mg alloy (A357) and the binary counterpart Al-7wt.%Si have been directionally solidified upwards over a wide range of constant solidification …
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Multifractal Analysis of Geomagnetically Induced Currents using Wavelet Leaders
… the solar wind and carrying with it the sun’s rotating magnetic field. The solar wind subsequently interacts with Earth’s magnetosphere and the magnetospheres of other planets. Occasionally large amounts of magnetized plasma are released at one time in a Corona mass ejection (CME). When the CME …
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Electromagnetic extraction and annihilation of antiprotons for spacecraft propulsion
… magnetospheres is developed. The excitation via rotating magnetic field of an electron population within a distributed neutral plasma is shown to produce a large-scale magnetic field approximating a dipole with r-² or slower decay. These shallow field gradients are, in turn, found to suppress the …
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Characterizing ferrofluid spin-up flow in rotating uniform magnetic fields
A ferrofluid is a collection of nanoscale ferromagnetic particles with a stabilizing surfactant in a liquid to form a colloid. The dynamic behavior of ferrofluids in the presence of magnetic fields has long been an area of research interest. A particular area of interest deals with the "spin-up" …
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Continuum modeling of polarizable systems
… Couette flow of ferrofluids in alternating and rotating uniform magnetic fields, including the effects of couple stresses. We obtain analytical expressions for the translational and spin velocity profiles, vorticity profiles, volumetric flow rate, and the shear force on a moving duct surface, …
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Polymer coated superparamagnetic beads walking on polymer coated surface
… examines walkers that are created using superparamagnetic beads placed in a rotating external magnetic field. Dipoles align in the beads so they assemble into rotors. These rotors follow the rotating magnetic field and are able to translate across a surface. This work looks at the effect of …
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Studies of Highly Polar Atomic and Molecular Systems: Quantum Dynamics and the Route to Experimental Investigations
… to manipulate using readily-available electric fields. A model two-level system is used to derive one approach for maximizing the probability of adiabatic passage through an avoided crossing and this is compared with the classic Landau-Zener result, and the commonly encountered spin-flip problem …
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Collective behavior of driven Janus colloids in external fields
… structures with novel functions. In this thesis, magnetic and electric fields are employed to inject energy into Janus colloids, particles with two sides of different properties. Many interesting dynamics are observed for single particles as well as the whole system. Meanwhile, a plethora of …
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Single Degree of Freedom Solid Rotor Velocity Control Induction Drive
… to provide a 3-phase drive resulting in a rotating magnetic field. Each coil is powered by a custom linear transconductance amplifier with 5 kHz bandwidth and 0.3 A/V DC gain. The controller receives feedback through a contact-less magnetic encoder providing a linear voltage measurement of …
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Dynamic Self-Assembly of Magnetic Colloidal Particles
… where inertia can be neglected. Creeping flow magnetic systems can be characterized by the Mason number. The Mason number measures the ratio between the viscous and the magnetic torque and is the main parameter governing the behavior of paramagnetic colloids investigated in this thesis. The …
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Estimation of rotor flux of an induction machine
… chart.Chapter 2 presents the basic principals of rotating magnetic field of the IM and asserts brief overview of the AC machines. Later it talks about different kinds of IM rotors suggesting which one is good. It is crucial to start with good and appropriate reviews which were verified by numerous …
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Closed-Loop Control of Mesoscale Magnetic Robots Using a Global Magnetic Field
… three types of mesoscale (milli- and microscale) magnetic robots: magnetic swimmers, magnetic modular cubes, and ferromagnetic micro-particles. Mesoscale magnetic robots show great potential for revolutionizing many aspects of medical and clinical applications. The dissertation investigates …
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Synthetic creation of a chemotactic system via utilization of magnetically actuated microrobotic walkers
… synthetic chemotactic system which utilized magnetically actuated microrobotic walkers. The system used a rotating magnetic field that once actuated induced the magnetic beads to self-assemble into microrobots and walk on surfaces. The velocity of these microrobotic walkers could be modulated …
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