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Full-Text Articles in Physics

Fitting Solar Panel Brdf Parameters To Out-Of-Plane Empirical Data, Michael R. Gross Dec 2022

Fitting Solar Panel Brdf Parameters To Out-Of-Plane Empirical Data, Michael R. Gross

Theses and Dissertations

The bidirectional reflectance distribution function (BRDF) describes material reflectance by describing how incident irradiance reflects into all possible scatter angles as a function of incident angle. However, a solar panel has unique features that are not featured in any of these previously known models. A previous project at the Air Force Institute of Technology (AFIT) created a novel microfacet-like BRDF to model a solar panel with a prominent diffractive feature present which had not been previously modeled. This BRDF was coded into MATLAB for modeling purposes and C++ to test its speed with a MEX function call. A previous thesis …


Development Of A Low Field Mri-Based Approach For Observation Of Water Penetration Into Clay: Preliminary Results, Shivam Gupta Aug 2021

Development Of A Low Field Mri-Based Approach For Observation Of Water Penetration Into Clay: Preliminary Results, Shivam Gupta

Undergraduate Student Research Internships Conference

Magnetic resonance imaging (MRI) are considered one of the most efficient and non-invasive methods of observing water content in permeable substances. MRI can visualize and quantify the movement of water in real time. In this study, MRI was used to observe the water penetration through clay. Furthermore, MRI can acquire three-dimensional data due to its radio-frequency signals from any orientation. The contrast of the images produced by MRI is a display of the fluid concentration. As such, any change in the contrast intensity is interpreted as a regional change in the concentration of fluid. This report summarizes the preliminary results …


Simulating 129-Xe Hyperpolarization, Jacob F. Abiad Aug 2021

Simulating 129-Xe Hyperpolarization, Jacob F. Abiad

Undergraduate Student Research Internships Conference

Hyperpolarized 129-Xe is an important resource in many fields of medical physics and MRI research. The physics of the efficient production of hyperpolarized 129-Xe is therefore equally worth investigation. The main process of hyperpolarizing 129-Xe is Spin Exchange Optical Pumping (SEOP) and is dependent on several physical factors that can be difficult to constantly change in a lab setting. Physical modelling of 129-Xe hyperpolarization allows for the more efficient testing of hyperpolarization physics in a wide array of experimental setups to better determine the optimal values for hyperpolarization. This research project attempted to create a working model for 129-Xe hyperpolarization …


Comparing Semi-Automated Segmentation Of Traditional-Resolution And High-Resolution Hyperpolarized 129xe Mri On Covid-19 Survivors, Tingting Wu Aug 2021

Comparing Semi-Automated Segmentation Of Traditional-Resolution And High-Resolution Hyperpolarized 129xe Mri On Covid-19 Survivors, Tingting Wu

Undergraduate Student Research Internships Conference

Hyperpolarized gas MRI using inert gases like Xe is a valuable tool in visualizing lung ventilation in patients, and can be used as a longitudinal monitoring tool for patients with lung diseases. However, use of this method requires segmentation and quantification of parameters such as ventilation defect percentage (VDP), which is often very subjective depending on the observer. This study aimed to determine the accuracy and consistency of VDP calculation using the same MRI scans from COVID-19 patients, but with high resolution and low (traditional) resolution versions. Using a MATLAB script developed previously, it was found that in general, using …


Changes In The Scattering Phase Shifts For Partial Waves Of Ultracold Particles At Different Energies, Kaaviyan Faezi May 2020

Changes In The Scattering Phase Shifts For Partial Waves Of Ultracold Particles At Different Energies, Kaaviyan Faezi

Honors Scholar Theses

At low energies, scattering phase shifts, the difference in phases between the incoming and outgoing spherical waves in scattering, for different partial waves follow a similar pattern. The phase shift curves, which are a function of the angular momentum quantum number for different scattering energy, obtain resonances after reaching their maxima, and as energy is increased, these resonances become smaller and eventually disappear. Using numerical methods involving the use of Chebyshev polynomials, we solve the wave equation for a scattering potential to obtain the radial equation. From the radial equation we then find the scattering phase shift for a particular …


Numerical Solution Of 3rd Order Ode Using Fdm: On A Moving Surface In Mhd Flow Of Sisko Fluid, Manisha Patel, Jayshri Patel, M. G. Timol Jun 2019

Numerical Solution Of 3rd Order Ode Using Fdm: On A Moving Surface In Mhd Flow Of Sisko Fluid, Manisha Patel, Jayshri Patel, M. G. Timol

Applications and Applied Mathematics: An International Journal (AAM)

A Similarity group theoretical technique is used to transform the governing nonlinear partial differential equations of two dimensional MHD boundary layer flow of Sisko fluid into nonlinear ordinary differential equations. Then the resulting third order nonlinear ordinary differential equation with corresponding boundary conditions is linearised by Quasi linearization method. Numerical solution of the linearised third order ODE is obtained using Finite Difference method (FDM). Graphical presentation of the solution is given.


Seeing Eye To Eye: A Machine Learning Approach To Automated Saccade Analysis, Maigh Attre May 2019

Seeing Eye To Eye: A Machine Learning Approach To Automated Saccade Analysis, Maigh Attre

Honors Scholar Theses

Abnormal ocular motility is a common manifestation of many underlying pathologies particularly those that are neurological. Dynamics of saccades, when the eye rapidly changes its point of fixation, have been characterized for many neurological disorders including concussions, traumatic brain injuries (TBI), and Parkinson’s disease. However, widespread saccade analysis for diagnostic and research purposes requires the recognition of certain eye movement parameters. Key information such as velocity and duration must be determined from data based on a wide set of patients’ characteristics that may range in eye shapes and iris, hair and skin pigmentation [36]. Previous work on saccade analysis has …


Finite Element Solution Of The Two-Dimensional Incompressible Navier-Stokes Equations Using Matlab, Endalew G. Tsega, V. K. Katiyar Jun 2018

Finite Element Solution Of The Two-Dimensional Incompressible Navier-Stokes Equations Using Matlab, Endalew G. Tsega, V. K. Katiyar

Applications and Applied Mathematics: An International Journal (AAM)

The Navier–Stokes equations are fundamental in fluid mechanics. The finite element method has become a popular method for the solution of the Navier-Stokes equations. In this paper, the Galerkin finite element method was used to solve the Navier-Stokes equations for two-dimensional steady flow of Newtonian and incompressible fluid with no body forces using MATLAB. The method was applied to the lid-driven cavity problem. The eight-noded rectangular element was used for the formulation of element equations. The velocity components were located at all of 8 nodes and the pressure variable is located at 4 corner of the element. From location of …