Physical Sciences and Mathematics Commons^™

Experimental Investigation Of A Non-Thermal Atmospheric Pressure Plasma Jet, Asma Begum

Electrical & Computer Engineering Theses & Dissertations

The main objective of this dissertation is to understand the formation of the plasma jet from the plasma pencil, and the propagation of the plasma jet in the ambient atmosphere where the effect of the external electric field is almost zero. Before investigating the formation and propagation phenomenon of the plasma jet, common physical properties of plasma jets are determined by using the imaging technique and optical emission spectroscopy. The first goal of this dissertation is to establish the laminar helium gas flow channel through a plasma pencil.

The formation position, formation time, and the criterion of the plasma jet …

Simultaneous Higher Harmonic Detection And Extraction Of Information From Oxygen Spectra, Karan Dineshchandra Mohan

Electrical & Computer Engineering Theses & Dissertations

Wavelength Modulation Spectroscopy (WMS) is a highly sensitive technique that utilizes synchronous detection at the N-th harmonics of a modulating frequency, by modulating the laser beam used to probe a gaseous species. The advantage of this technique lies in the greater effective signal-to-noise ratio one obtains as a direct consequence of the larger amount of structure present in the higher harmonics, and thus a greater amount of information that can be obtained from that structure. We present the development of a novel technique where data at multiple harmonics is obtained simultaneously, rather than sequentially. This removes the susceptibility of the …

Nuclear Electromagnetic Currents In Chiral Effective Field Theory, Saori Pastore

Physics Theses & Dissertations

A nucleon-nucleon potential and consistent nuclear electromagnetic currents are derived in chiral effective field theory retaining pions and nucleons as explicit degrees of freedom. The calculation of the potential is carried out up to next-to-next-to leading order (N²LO), while the currents include up to N³LO corrections. The potential at N² LO and currents at N³LO consist of two-pion-exchange and contact contributions. The currents are then utilized to study a number of low-energy electromagnetic observables induced by magnetic dipole transitions, such as the deuteron and trinucleon magnetic moments and the np, nd and n …

Structure Prediction For The Helical Skeletons Detected From The Low Resolution Protein Density Map, Kamal Al Nasr, Weitao Sun, Jing He

Computer Science Faculty Publications

Background: The current advances in electron cryo-microscopy technique have made it possible to obtain protein density maps at about 6-10 Å resolution. Although it is hard to derive the protein chain directly from such a low resolution map, the location of the secondary structures such as helices and strands can be computationally detected. It has been demonstrated that such low-resolution map can be used during the protein structure prediction process to enhance the structure prediction.

Results: We have developed an approach to predict the 3-dimensional structure for the helical skeletons that can be detected from the low resolution protein density …

Excitation-Induced Germanium Quantum Dot Formation On Si (100)-(2×1), Ali Oguz Er, Hani E. Elsayed-Ali

Physics Faculty Publications

The effect of nanosecond pulsed laser excitation on the self-assembly of Ge quantum dots grown by pulsed laser deposition on Si (100)-(2×1) was studied. In situ reflection high-energy electron diffraction and ex situ atomic force microscopy were used to probe the quantum dot structure and morphology. At room temperature, applying the excitation laser decreased the surface roughness of the grown Ge film. With surface electronic excitation, crystalline Ge quantum dots were formed at 250 °C, a temperature too low for their formation without excitation. At a substrate temperature of 390 °C, electronic excitation during growth was found to improve the …

Prediction Of Brain Tumor Progression Using A Machine Learning Technique, Yuzhong Shen, Debrup Banerjee, Jiang Li, Adam Chandler, Yufei Shen, Frederic D. Mckenzie, Jihong Wang, Nico Karssemeijer (Ed.), Ronald M. Summers (Ed.)

Electrical & Computer Engineering Faculty Publications

A machine learning technique is presented for assessing brain tumor progression by exploring six patients' complete MRI records scanned during their visits in the past two years. There are ten MRI series, including diffusion tensor image (DTI), for each visit. After registering all series to the corresponding DTI scan at the first visit, annotated normal and tumor regions were overlaid. Intensity value of each pixel inside the annotated regions were then extracted across all of the ten MRI series to compose a 10 dimensional vector. Each feature vector falls into one of three categories:normal, tumor, and normal but progressed to …

Experimental Studies On The Plasma Bullet Propagation And Its Inhibition, Erdinc Karakas, Mounir Laroussi

Electrical & Computer Engineering Faculty Publications

Plasma bullets generated by atmospheric pressure low temperature plasma jets have recently been an active research topic due to their unique properties and their enhanced plasma chemistry. In this paper, experimental insights into the plasma bullet lifetime and its velocity are reported. Data obtained from intensified charge-coupled device camera and time-resolved optical emission spectroscopy (OES) elucidated the existence of a weakly ionized channel between the plasma bullet and its source (such as the plasma pencil). Factors responsible for the inhibition of the propagation of the bullet, such as low helium mole fraction, the magnitude of the applied voltage, and the …

Design Of Organic Tandem Solar Cells Using Pcpdtbt: Pc61 Bm And P3ht: Pc71bm, Gon Namkoong, Patrick Boland, Keejoo Lee, James Dean

Electrical & Computer Engineering Faculty Publications

We conducted optical and electrical simulations with the goal of determining the optimal design for conjugated polymer-fullerene tandem solar cells using poly[2,6-(4,4-bis-(2-ethylhexyl)- 4H-cyclopenta[2,1- b;3,4- b′] dithiophene)-alt-4,7-(2,1,3-benzothiadiazole)] (PCPDTBT): [6,6]-phenyl C₆₁ butyric acid methyl ester (PC₆₁ BM) as a bottom cell and poly(3-hexylthiophene) (P3HT): [6,6]-phenyl C₇₁ butyric acid methyl ester (PC₇₁BM) as a top cell. The effects of photon density, absorption, balanced and unbalanced charge carrier transport, and bimolecular recombination in the two subcells were incorporated into the simulations. We found that the maximum energy conversion efficiency (η) is 9% when charge carrier mobilities in …

Finite Element Analysis Of Ring-Shaped Emission Profile In Plasma Bullet, Yukinori Sakiyama, David B. Graves, Julien Jarrige, Mounir Laroussi

Electrical & Computer Engineering Faculty Publications

Using a one-way coupled model of neutral gas flow and plasma dynamics we report a mechanism to explain the ring-shaped emission pattern that has been observed experimentally in plasma bullets at atmospheric pressure. We solve a fluid model with the local field approximation in one-dimensional cylindrical coordinates, corresponding to a cross-section of a plasma bullet. Pulselike uniform electric field is assumed to be applied perpendicular to the simulation domain. Time and spatially resolved spectroscopic measurements support the simulation results.