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Terahertz Imaging For Cancer Detection, Benjamin A. St. Peter 2012 University of Massachusetts Amherst

Terahertz Imaging For Cancer Detection, Benjamin A. St. Peter

Masters Theses 1911 - February 2014

This project evaluates the ability of terahertz (THz) radiation to differentiate cancerous from non-cancerous human breast lumpectomy and mastectomy tissue. This is done by aiming a narrow-band THz beam at medical samples and measuring reflected power. THz images of specimens from Breast Conservation Surgery (BCS) were created using a gas laser source and mechanical scanning. The design and characterization of this system is discussed in detail. The images were correlated with optical histological micrographs of the same specimens and discrimination values of more than 70% were found for five of the six samples using Receiver Operating Characteristic (ROC) analysis.


High-Q Bismuth-Silicate Nonlinear Glass Microsphere Resonators, Pengfei Wang, Ganapathy Murugan, Timothy Lee, Ming Ding, Gilberto Brambilla, Yuliya Semenova, Qiang Wu, Fumihito Koizumi, Gerald Farrell 2012 Dublin Institute of Technology

High-Q Bismuth-Silicate Nonlinear Glass Microsphere Resonators, Pengfei Wang, Ganapathy Murugan, Timothy Lee, Ming Ding, Gilberto Brambilla, Yuliya Semenova, Qiang Wu, Fumihito Koizumi, Gerald Farrell

Articles

The fabrication and characterization of a bismuth-silicate glass microsphere resonator has been demonstrated. At wavelengths near 1550 nm, high-modes can be efficiently excited in a 179-μm diameter bismuth-silicate glass microsphere via evanescent coupling using a tapered silica fiber with a waist diameter of circa 2 μm. Resonances with Q-factors as high as were observed. The dependence of the spectral response on variations in the input power level was studied in detail to gain an insight into power-dependent thermal resonance shifts. Because of their high nonlinearity and high- factors, bismuth-silicate glass microspheres offer the potential for robustly assembled fully integrated all-optical ...


High Temperature Performance Of An Optical Microfibre Coupler And Its Potential Use As A Sensor, Pengfei Wang, Ming Ding, Gilberto Bramilla, Yuliya Semenova, Qiang Wu, Gerald Farrell 2012 Dublin Institute of Technology

High Temperature Performance Of An Optical Microfibre Coupler And Its Potential Use As A Sensor, Pengfei Wang, Ming Ding, Gilberto Bramilla, Yuliya Semenova, Qiang Wu, Gerald Farrell

Articles

The dependence of the transmission spectrum of an optical microfibre coupler at high temperatures is investigated experimentally. Results show a temperature sensitivity up to 36.59 pm/oC at a taper waist outer diameter of 2.5 μm; such a temperature-dependent performance can be utilized for temperature sensing up to 1000oC.


Enhanced Refractometer Based On Periodically Tapered Small Core Singlemode Fiber, Pengfei Wang, Gilberto Brambilla, Ming Ding, Timothy Lee, Lin Bo, Yuliya Semenova, Qiang Wu, Gerald Farrell 2012 Dublin Institute of Technology

Enhanced Refractometer Based On Periodically Tapered Small Core Singlemode Fiber, Pengfei Wang, Gilberto Brambilla, Ming Ding, Timothy Lee, Lin Bo, Yuliya Semenova, Qiang Wu, Gerald Farrell

Articles

Abstract—An all-fiber 1 refractive index (RI) sensor with a 2 simple configuration of periodical tapers is proposed and inves3 tigated experimentally. The proposed fiber RI sensor consists of 4 a small core fiber sandwiched between two standard singlemode 5 fibers, with tapers periodically fabricated along the small core 6 fiber using a focused CO2 laser beam. Such a structure can be 7 used for RI sensing by measuring the dip wavelength shift of 8 the multimode interference within the small core fiber cladding. 9 An average sensitivity of 226.6 nm/RIU (RI Unit) has been 10 experimentally achieved ...


Developments In Deep Brain Stimulation Using Time Dependent Magnetic Fields, Lawrence J. Crowther, Cajetan Ikenna Nlebedim, David C. Jiles 2012 Iowa State University

Developments In Deep Brain Stimulation Using Time Dependent Magnetic Fields, Lawrence J. Crowther, Cajetan Ikenna Nlebedim, David C. Jiles

Electrical and Computer Engineering Publications

The effect of head model complexity upon the strength of field in different brain regions for transcranial magnetic stimulation (TMS) has been investigated. Experimental measurements were used to verify the validity of magnetic field calculations and induced electric field calculations for three 3D human head models of varying complexity. Results show the inability for simplified head models to accurately determine the site of high fields that lead to neuronal stimulation and highlight the necessity for realistic head modeling for TMS applications.


Effect Of Deviation From Stoichiometric Composition On Structural And Magnetic Properties Of Cobalt Ferrite, Coxfe3−Xo4 (X = 0.2 To 1.0), Cajetan Ikenna Nlebedim, J. E. Snyder, A. J. Moses, David C. Jiles 2012 Iowa State University

Effect Of Deviation From Stoichiometric Composition On Structural And Magnetic Properties Of Cobalt Ferrite, Coxfe3−Xo4 (X = 0.2 To 1.0), Cajetan Ikenna Nlebedim, J. E. Snyder, A. J. Moses, David C. Jiles

Electrical and Computer Engineering Publications

The effects of deviation from stoichiometric composition on the structural and magnetic properties of cobaltferrite, CoxFe3−xO4 (x = 0.2 to 1.0), are presented. Both CoFe2O4 and Fe3O4have a spinel crystal structure, and it might be expected that intermediate compositions would have the same structure. However, results show that synthesis via the ceramic method leads to the development of a secondary α-Fe2O3 phase. Both structural and magnetic properties are altered depending on the concentration of the α-Fe2O3 phase. Saturation magnetization is ...


Optimization Ofmagnetooptic Device By Low Switching Field Domains, Jin-Wei Tioh, Sasha Oster, Mani Mina, Robert J. Weber 2012 Iowa State University

Optimization Ofmagnetooptic Device By Low Switching Field Domains, Jin-Wei Tioh, Sasha Oster, Mani Mina, Robert J. Weber

Electrical and Computer Engineering Publications

This paper expounds on the optimization of magnetooptic devices using preferential domains that switch at low field strengths. In particular, an all-optical switch for transparent networks based on theMach-Zehnder interferometer configuration is examined in detail. The switch utilizes bismuth-substituted iron garnets with a specific composition of (Bi1.1Tb1.9)(Fe4.25Ga0.75)O12 as Faraday rotators. It is proposed that switch figures of merit can be improved by preferentially choosing domains which align with applied fields at field strengths much lower than required by the bulk material. Measurement of magnetic domain orientation in ...


Low Power Field Generation For Magneto-Optic Fiber-Based Interferometric Switches, John Paul Pritchard Jr., Mani Mina, Robert J. Weber, Sasha Kemmet 2012 Iowa State University

Low Power Field Generation For Magneto-Optic Fiber-Based Interferometric Switches, John Paul Pritchard Jr., Mani Mina, Robert J. Weber, Sasha Kemmet

Electrical and Computer Engineering Publications

A new fiber-based, magneto-optic switch is proposed with a novel approach for low power and efficient operation. The switch, with reasonable switching speed compared to competitive designs, operates at considerably reduced power levels, which makes it a practical deployable solution. The basic switch setup consists of a Faraday rotator in a Sagnac fiber-optic interferometer in which optical switching is controlled by an electronic driving circuit. The electronic system generates a magnetic field through the Faraday rotator by driving current through a specially designed two-coil system. The new coil system allows for sufficient field generation at low quiescent power levels while ...


Efficient And Accurate Approximation Of Infinite Series Summation Using Asymptotic Approximation And Fast Convergent Series, Sidharath Jain, Jiming Song 2012 Iowa State University

Efficient And Accurate Approximation Of Infinite Series Summation Using Asymptotic Approximation And Fast Convergent Series, Sidharath Jain, Jiming Song

Electrical and Computer Engineering Publications

We present an approach for very quick and accurate approximation of infinite series summation arising in electromagnetic problems. This approach is based on using asymptotic expansions of the arguments and the use of fast convergent series to accelerate the convergence of each term. It has been validated by obtaining very accurate solution for propagation constant for shielded microstrip lines using spectral domain approach (SDA). In the spectral domain analysis of shielded microstrip lines, the elements of the Galerkin matrix are summations of infinite series of product of Bessel functions and Green's function. The infinite summation is accelerated by leading ...


Multi-Wavelength, Multi-Beam, Photonic Based Sensor For Object Discrimination And Positioning, Kavitha Venkataraayan 2012 Edith Cowan University

Multi-Wavelength, Multi-Beam, Photonic Based Sensor For Object Discrimination And Positioning, Kavitha Venkataraayan

Theses: Doctorates and Masters

Over the last decade, substantial research efforts have been dedicated towards the development of advanced laser scanning systems for discrimination in perimeter security, defence, agriculture, transportation, surveying and geosciences. Military forces, in particular, have already started employing laser scanning technologies for projectile guidance, surveillance, satellite and missile tracking; and target discrimination and recognition. However, laser scanning is relatively a new security technology. It has previously been utilized for a wide variety of civil and military applications. Terrestrial laser scanning has found new use as an active optical sensor for indoors and outdoors perimeter security. A laser scanning technique with moving ...


Non-Metallic Metamaterials: Modelling, Design, And Fabrication Tolerances Analysis, Yang Li 2012 Iowa State University

Non-Metallic Metamaterials: Modelling, Design, And Fabrication Tolerances Analysis, Yang Li

Graduate Theses and Dissertations

Metamaterials are artificial materials, consisting of sub-wavelength building blocks, which can show anomalous and exotic electromagnetic responses. Metal-based metamaterials, as the first experimentally implemented metamaterials, have achieved significant progress in theory, fabrication, and characterization over a broad frequency range from microwave to visible. To

alleviate the drawbacks of metal-based metamaterials, such as conductive loss and anisotropy, non-metallic metamaterials have been proposed and developed rapidly in the last decade. This thesis focuses on the analytical modeling and fabrication-tolerance analysis of non-metallic metamaterials consisting of an array of magnetodielectric spheres. Here, the term "magnetodielectric" refers, generally, to materials with relative permittivity and ...


Evaluation Of Crack Signals In Cylindrical Structures Using Eddy Current Nondestructive Evaluation Theory, Hui Xie 2012 Iowa State University

Evaluation Of Crack Signals In Cylindrical Structures Using Eddy Current Nondestructive Evaluation Theory, Hui Xie

Graduate Theses and Dissertations

The modeling of eddy current (EC) problems is not only helpful for the probe design and the interpretation of measurement data, but also essential to the corresponding inverse problems. In order to deal with high conductivity and low operating frequency, the conventional pure numerical methods require large memory and long computing time to accurately solve EC problems. In this dissertation, semi-analytical approaches are presented to efficiently solve a series of EC problems in cylindrical polar coordinates.

By applying the truncation in an unbounded domain, the fields are expanded into a linear combination of the eigenfunctions. Each eigenfunction belongs to different ...


Electromagnetic Scattering In A Discrete Basis, Christopher Paul Trampel 2012 Iowa State University

Electromagnetic Scattering In A Discrete Basis, Christopher Paul Trampel

Graduate Theses and Dissertations

In this dissertation, I use discrete eigenfunction expansions to study three electromagnetic scattering problems in the frequency domain. Chapter 2 describes an eddy-current coil interacting with a perfectly conducting wedge of arbitrary angle. A closed-form expression for the impedance of a tangential eddy-current coil in the presence of an infinite conducting wedge of arbitrary angle is derived. The truncated eigenfunction expansion (TREE) solution given here is valid in the quasi-static frequency regime. The theory was validated via comparison to an independent analytical expression for the impedance change of a horizontal coil over a conducting half-space due to Burke. I present ...


Simulations Of A Langmuir Probe, Densu Aktas 2011 Selected Works

Simulations Of A Langmuir Probe, Densu Aktas

Densu Aktas

The Langmuir probe is used as a diagnostic devise to determine the properties of plasma, which is a state of matter that is partially or wholly ionized gas containing free charged particles; free moving electrons and ions. This probe is used to determine the plasma characteristics such as temperature and density by carefully analyzing the probe voltage-current (V-I) characteristics. However, real world effects, such as finite length geometry, cause the measurements from these probes to deviate from the theoretical predictions for ideal probes. To understand these discrepancies and predict the performance of real probes, computer simulations using the Particle-in-Cell (PIC ...


Experimental Verification Of The Linear Relationship Between Stress And The Reciprocal Of The Peak Barkhausen Voltage In Astm A36 Steel, Orfeas Kypris, Ikenna Nlebedim, David Jiles 2011 University of Oxford

Experimental Verification Of The Linear Relationship Between Stress And The Reciprocal Of The Peak Barkhausen Voltage In Astm A36 Steel, Orfeas Kypris, Ikenna Nlebedim, David Jiles

Orfeas Kypris

This study presents an experimental validation of a model theory for determining the relationship between a nondestructive measurement parameter and a property of interest. It was found that the reciprocal of the peak envelope amplitude of the Barkhausen emission voltage follows a linear relationship with stress. A linear relationship between stress and the reciprocal of the root mean square voltage was also obtained. These observations represent an important step towards improving the use of Barkhausen signals for magnetic non-destructive evaluation of stress as a function of depth in ferromagnetic load bearing structures.


Spreading Profile Of Evaporative Liquid Drops In Thin Porous Layer, Faisal Rafiq Mahamd Adikan 2011 University of Malaya

Spreading Profile Of Evaporative Liquid Drops In Thin Porous Layer, Faisal Rafiq Mahamd Adikan

Faisal Rafiq Mahamd Adikan

Spreading of evaporative liquid drops in a thin porous layer has been studied. The entire spreading process can be divided into three distinct phases according to the change of the wetted porous region size. The first phase is characterized by the expansion of the wetted porous region and shrinking of the liquid drop. Contact line pinning is observed in the wetted porous region in the second phase even with the liquid drop totally absorbed into the porous layer. The third phase sees the shrinkage of the wetted porous region until it is not observable. Based on these observations, a model ...


Optical System For Open Orbiter, Nick Long, Dillon Hasselmenn, Rachael Roberts, Patrick Galegher, Noah Root, Josh Berk, Jeremy Straub 2011 Selected Works

Optical System For Open Orbiter, Nick Long, Dillon Hasselmenn, Rachael Roberts, Patrick Galegher, Noah Root, Josh Berk, Jeremy Straub

Jeremy Straub

No abstract provided.


Evaluation Of The Transient Potential Drop Of A Four-Point Probe, John R. Bowler 2011 Iowa State University

Evaluation Of The Transient Potential Drop Of A Four-Point Probe, John R. Bowler

John R. Bowler

The time-dependent voltage across the pick-up electrodes of a four point probe has been determined analytically for a transient current pulse injected into a thick conductive plate modeled as a half-space. This is a step towards analyzing more complex transient four point probe signals from measurements on inhomogeneous conductors. Potential applications include the evaluation of depth-dependent conductivity profiles in metals and semiconductors. The analysis of homogeneous conductors shows how the signals are characterized by a time constant of the drive current and additional time constants dependent on the electromagnetic material properties and electrode spacings


Payload Software, Christoffer Korvald, Jeremy Straub, Atif Mohammad, Josh Berk 2011 Selected Works

Payload Software, Christoffer Korvald, Jeremy Straub, Atif Mohammad, Josh Berk

Jeremy Straub

No abstract provided.


An Analytical Model Of A Ferrite-Cored Inductor Used As An Eddy Current Probe, John R. Bowler, Yi Lu, Theodoros P. Theodoulidis 2011 Iowa State University

An Analytical Model Of A Ferrite-Cored Inductor Used As An Eddy Current Probe, John R. Bowler, Yi Lu, Theodoros P. Theodoulidis

John R. Bowler

An analytical model of an axisymmetric eddy current ferrite-cored probe above a multi-layered conducting half-space has been developed using a procedure in which the domain of the problem is truncated radially. This means that solutions can be expressed in the form of generalized Fourier-Bessel series. The expansion coefficients are found by matching the field across the interfaces between the subregions of the problem. Initially, the magnetic vector potential of a simple circular current filament is expanded in a series form. The solution is then modified to accommodate an infinitely long coaxial ferrite core, and the principle of superposition is invoked ...


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