Physics Commons^™

Fast Absolute Quantification Of In Vivo Water And Fat Content With Magnetic Resonance Imaging, Yifan Cui

Electronic Thesis and Dissertation Repository

Quantitative water fat imaging offers a non-invasive method for monitoring and staging diseases associated with changes in either water or fat content in tissue. In this work absolute water and fat mass density measurement with in vivo Magnetic Resonance Imaging (MRI) is demonstrated. T₁ independent, T₂^* corrected chemical shift based water-fat separated images are acquired. By placing a phantom with known mass density in the field of view for signal intensity calibration, absolute water or fat mass density can be computed, assuming the B₁⁺ (transmit) and B₁^- (receive) fields can be measured. Phantom …

Validation Of Weak Form Thermal Analysis Algorithms Supporting Thermal Signature Generation, Elton Lewis Freeman

Masters Theses

Extremization of a weak form for the continuum energy conservation principle differential equation naturally implements fluid convection and radiation as flux Robin boundary conditions associated with unsteady heat transfer. Combining a spatial semi-discretization via finite element trial space basis functions with time-accurate integration generates a totally node-based algebraic statement for computing. Closure for gray body radiation is a newly derived node-based radiosity formulation generating piecewise discontinuous solutions, while that for natural-forced-mixed convection heat transfer is extracted from the literature. Algorithm performance, mathematically predicted by asymptotic convergence theory, is subsequently validated with data obtained in 24 hour diurnal field experiments for …

Preoperative Planning Of Robotics-Assisted Minimally Invasive Cardiac Surgery Under Uncertainty, Hamidreza Azimian

Electronic Thesis and Dissertation Repository

In this thesis, a computational framework for patient-specific preoperative planning of Robotics-Assisted Minimally Invasive Cardiac Surgery (RAMICS) is developed. It is expected that preoperative planning of RAMICS will improve the rate of success by considering robot kinematics, patient-specific thoracic anatomy, and procedure-specific intraoperative conditions. Given the significant anatomical features localized in the preoperative computed tomography images of a patient's thorax, port locations and robot orientations (with respect to the patient's body coordinate frame) are determined to optimize characteristics such as dexterity, reachability, tool approach angles and maneuverability. In this thesis, two approaches for preoperative planning of RAMICS are proposed that …

High Frequency Study Of Magnetic Nanostructures, Abhishek Srivastava

University of New Orleans Theses and Dissertations

The work in this thesis is divided in three parts. In part one we developed electrodeposition method of Nickel Nanowire in commercial AAO template in constant current (Galvanostatic) mode, further we tried to estimate the growth rate from theory, from saturation magnetization and direct measurement from SEM image.

In part two we focused on using the Vector Network Analyzer (VNA) to measure the Ferromagnetic Resonance (FMR))of various magnetic Nanowire arrays. We employed different measurement geometries using microstripline and coplanar waveguide as microwave transmission lines.

In part three our aim was to study the magnetic properties of complex ferromagnetic system, especially …

Morphology-Properties Studies In Laser Synthesized Nanostructured Materials, Nozomi Shirato

Doctoral Dissertations

Synthesis of well-defined nanostructures by pulsed laser melting is an interesting subject from both a funda- mental and technological point of view. In this thesis, the synthesis and functional properties of potentially useful materials were studied, such as tin dioxide nanostructured arrays, which have potential applications in hydrogen gas sensing, and ferromagnetic Co nanowire and nanomagnets, which are fundamentally im- portant towards understanding magnetism in the nanoscale. First, the formation of 1D periodic tin dioxide nanoarrays was investigated with the goal of forming nanowires for hydrogen sensing. Experimental obser- vations combined with theoretical modeling successfully explained the mechanisms of structure …

The Double Pendulum: Construction And Exploration, Benjamin J. Knudson

Physics

The exploration of a nonlinear mechanical system, the Double Pendulum, a physical pendulum on the end of a physical pendulum, using analytic and experimental approaches. Also included discussion of the design and construction of the Double Pendulum apparatus to work with Vernier LabPro and LoggerPro. The apparatus outputs live data of the angles to a LoggerPro which collects and produces time evolution graphs as well as a corresponding animation lending itself to comparison with theoretical models. Normal mode frequencies are found both analytically and experimentally for the the general (real) double pendulum. Examples of both simple (periodic) and complex (chaotic) …

Study Of Jet Transverse Momentum And Jet Rapidity Dependence Of Dijet Azimuthal Decorrelations With The Dø Detector, Kiran Chakravarthula

Doctoral Dissertations

In a collision experiment involving highly energetic particles such as hadrons, processes at high momentum transfers can provide information useful for many studies involving Quantum Chromodynamics (QCD). One way of analyzing these interactions is through angular distributions. In hadron-hadron collisions, the angular distribution between the two leading jets with the largest transverse momentum (pT) is affected by the production of additional jets. While soft radiation causes small differences in the azimuthal angular distribution of the two leading jets produced in a collision event, additional hard jets produced in the event have more pronounced influence on the distribution of …

Development Of A Pyrotechnic Shock Simulation Apparatus For Spacecraft Applications, Joseph Binder, Matthew Mccarty, Chris Rasmussen

Aerospace Engineering

This report details the research, design, construction, and testing of a pyrotechnic shock simulation apparatus for spacecraft applications. The apparatus was developed to be used in the Space Environments Lab at California Polytechnic State University. It will be used for testing spacecraft components with dimensions up to 24”x12”x12” as well as CubeSats. Additionally, it may be used as an instructional or demonstrational tool in the Aerospace Department’s space environments course. The apparatus functions by way of mechanical impact of an approximately 20 lb stainless steel swinging hammer. Tests were performed to verify the simulator’s functionality. Suggestions for improvement and further …

Analysis Of Focal-Plane Measurements For Veritas Telescopes, William Hemmo Schuur

Physics

In this experiment we measured the Point Spread Function (PSF) of the telescope at different image locations using a python GUI and servo motors to automate a screen along the focal axis of the telescope. Our results show that the telescope T4 has a well-defined image distance at each elevation, but this distance shifts as the telescope is lowered. Additionally, off-axis telescope orientations are degraded by aberrations and at low elevation possibly some structural warping of the mirror. The VERITAS Telescopes are located in Southern Arizona at the Fred Lawrence Whipple Observatory.

Inductive Metal Identification, Paul Maggi

Electrical Engineering

This project focuses on creating a device to differentiate between various types of metals via magnetic induction. Magnetic induction is used because it is both non-optical and non-contact. It achieves this by generating a varying magnetic field, which induces eddy currents in the metal. These eddy currents produce small disturbances in the surrounding magnetic field, which can be sensed with Hall Effect Sensors (HES). The primary challenge in this project was generating a sufficiently strong magnetic field to detectable disturbances. In order to achieve better results, a stronger magnetic field must be used as well as more sensitive Hall Effect …

Agent-Based Modeling Of Emergency Building Evacuation, Vi Q. Ha

Master's Theses

Panic during emergency building evacuation can cause crowd stampede, resulting in serious injuries and casualties. Agent-based methods have been successfully employed to investigate the collective human behavior during emergency evacuation in cases where the configurational space is extremely simple - usually one rectangular room - but not in evacuations of multi-room or multi-floor buildings. This implies that the effect of the complexity of building architecture on the collective behavior of the agents during evacuation has not been fully investigated. Here, we employ a system of self-moving particles whose motion is governed by the social-force model to investigate the effect of …

A Method To Measure The Detective Quantum Efficiency Of Radiographic Systems In Clinical Setting, Michael C. Mcdonald

Electronic Thesis and Dissertation Repository

The risks associated with exposure to radiation make it critical that digital imaging systems give the best possible images for a given dose to the patient. The DQE is the most widely accepted measure of performance and dose efficiency for digital radiography systems, however it is not commonly measured in a clinical environment as part of routine quality assurance. The primary reason for this is that the data provided to the user by clinical systems has typically undergone image processing and therefore may have a non-linear characteristic response. This is a problem because the Fourier metrics of the DQE require …

Breaking Glass: Exploring The Relationship Between Kinetic Energy And Radial Fracturing In Plate Glass, Andrea Hulman

Scripps Senior Theses

When glass breaks from the impact of an object, it exhibits a distinctive shattering pattern comprised of two different regions. This pattern was investigated using experimental impacts and predicted using Young’s Modulus. Results were not as expected, and it is likely that there exists error in some measurements. Further investigation of this topic is recommended.

Cesium Absorption Spectrum Perturbed By Argon: Observation Of Non-Lorentzian Far Wings, Gordon E. Lott

Theses and Dissertations

The purpose of this research was to observe the core and far wing absorption spectra of the D₁ and D₂ lines of cesium (Cs) perturbed by argon (Ar). A 1.33 m scanning monochromator with a PMT detector was used to measure the spectra from 8300 Å to 9100 Å. A heat pipe was used to control the Cs concentration and Ar pressure allowing for a broad range of spectra to be collected. Spectra were collected for heat pipe temperatures of 50, 75, 100, 125, 150 and 175 °C, corresponding to Cs concentrations of approximately 6×10¹¹, 4×10 …

Where Is The Best Place To Sit On A Roller Coaster? Forces, Physics, And Fun At Disneyland, Kelsey Lubetich

Scripps Senior Theses

The work presented in this thesis was undertaken to quantitatively determine the best place to sit on a roller coaster. Maximizing the time spent feeling weightless and the highest value of negative Z acceleration were used as criteria for the best seat. Acceleration values were measured on the California Screamin' roller coaster at Disney California Adventure Park using an iPhone and an application to record data from its accelerometers. After analyzing acceleration data, it was determined that the front row had the greatest negative acceleration in the z direction and was therefore the "best place" to sit.