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Surprising Results from Simple Model...

Bible, Jacob.

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Surprising Results from Simple Models: Magnetic and Elastic Self Focusing and Biomedical Applications.

紀錄類型:	書目-電子資源 : Monograph/item
正題名/作者:	Surprising Results from Simple Models: Magnetic and Elastic Self Focusing and Biomedical Applications./
作者:	Bible, Jacob.
出版者:	Ann Arbor : ProQuest Dissertations & Theses, : 2020,
面頁冊數:	130 p.
附註:	Source: Dissertations Abstracts International, Volume: 81-11, Section: B.
Contained By:	Dissertations Abstracts International81-11B.
標題:	Physics. -
電子資源:	https://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=27958913
ISBN:	9798643180548

Surprising Results from Simple Models: Magnetic and Elastic Self Focusing and Biomedical Applications.
Bible, Jacob.

Surprising Results from Simple Models: Magnetic and Elastic Self Focusing and Biomedical Applications. - Ann Arbor : ProQuest Dissertations & Theses, 2020 - 130 p.

Source: Dissertations Abstracts International, Volume: 81-11, Section: B.

Thesis (Ph.D.)--University of Colorado Colorado Springs, 2020.

This item must not be sold to any third party vendors.

This dissertation deals with simple approaches to a variety of excitations in materials. The excitations primarily include magnetic spin waves and elastics waves. The key point, however, is the new and interesting applications that can arise in these systems. In particular we develop theoretical descriptions for four main topics:The self-focusing of high-wave-vector magnonsThe self-focusing of high-wave-vector elastic wavesThe use of elastic waves to detect impurities through magnetic resonance imagingThe nonlinear motion of magnetic nanoparticles in a fluid when driven by an oscillating or rotating magnetic field.Each of these topics has important potential applications. For example, focusing of magnons could lead to signal processing devices in the microwave and infra-red frequencies. In contrast to earlier work, we theoretically calculate the focusing of short-wavelength spin waves. We show that strong focusing of large wave-vector spin waves naturally occurs about half-way out in the Brillouin zone with no need for a magnetocrystalline anisotropy, dipolar effects, or an external magnetic field. We also explore the tunability that is achieved by the application of both an external field and the presence of uniaxial anisotropy. In this case, an applied magnetic field produces a simple rotation of the focusing pattern, providing a simple and easily applicable tuning mechanism.As a second important example, we examine magnetic resonance elastography results in phantoms theoretically. In magnetic resonance elastography, a shear wave is introduced into the system along with a time-correlated gradient in an external magnetic field. This allows one to visualize elastic waves using magnetic resonance imaging. Because of the regular structure, the phantom system can display eigenmodes with standing wave patterns. We study whether these eigenmodes and associated eigenfrequencies have a significant effect on MRE measurements. The primary result is that driving the system at or near an eigenfrequency can have a significant result when data is collected over many periods. In addition, we develop a simple method, based on Fourier transforms which analyzes the MRE data to identify the location of an impurity.

ISBN: 9798643180548Subjects--Topical Terms:

516296
Physics.
Subjects--Index Terms:

Magnetic resonance elastography

Surprising Results from Simple Models: Magnetic and Elastic Self Focusing and Biomedical Applications.
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520 $a This dissertation deals with simple approaches to a variety of excitations in materials. The excitations primarily include magnetic spin waves and elastics waves. The key point, however, is the new and interesting applications that can arise in these systems. In particular we develop theoretical descriptions for four main topics:The self-focusing of high-wave-vector magnonsThe self-focusing of high-wave-vector elastic wavesThe use of elastic waves to detect impurities through magnetic resonance imagingThe nonlinear motion of magnetic nanoparticles in a fluid when driven by an oscillating or rotating magnetic field.Each of these topics has important potential applications. For example, focusing of magnons could lead to signal processing devices in the microwave and infra-red frequencies. In contrast to earlier work, we theoretically calculate the focusing of short-wavelength spin waves. We show that strong focusing of large wave-vector spin waves naturally occurs about half-way out in the Brillouin zone with no need for a magnetocrystalline anisotropy, dipolar effects, or an external magnetic field. We also explore the tunability that is achieved by the application of both an external field and the presence of uniaxial anisotropy. In this case, an applied magnetic field produces a simple rotation of the focusing pattern, providing a simple and easily applicable tuning mechanism.As a second important example, we examine magnetic resonance elastography results in phantoms theoretically. In magnetic resonance elastography, a shear wave is introduced into the system along with a time-correlated gradient in an external magnetic field. This allows one to visualize elastic waves using magnetic resonance imaging. Because of the regular structure, the phantom system can display eigenmodes with standing wave patterns. We study whether these eigenmodes and associated eigenfrequencies have a significant effect on MRE measurements. The primary result is that driving the system at or near an eigenfrequency can have a significant result when data is collected over many periods. In addition, we develop a simple method, based on Fourier transforms which analyzes the MRE data to identify the location of an impurity.
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