Physics Commons^™

Global Mhd And Acoustic Solar Modeling And Helioseismic Analysis, Andrey M. Stejko

Dissertations

Computational fluid dynamic simulations have become one of the most prolific avenues of study in the fields of solar and stellar physics within the last several decades. With the advent of ever increasing computing power, high-definition global models of the Sun have become indispensable in understanding the complex and chaotic nature of flows in the solar interior, as well as their impact on the evolution of the global solar dynamo. The mechanisms that connect the generation of the toroidal magnetic field at the base of the convection zone to the emergence of a poloidal field onto the solar surface can …

Asymmetric Multivariate Archimedean Copula Models And Semi-Competing Risks Data Analysis, Ziyan Guo

Dissertations

Many multivariate models have been proposed and developed to model high dimensional data when the dimension of a data set is greater than 2 (d ≥ 3). The existing multivariate models often force the “exchangeable” structure for part or the whole model, are not very flexible which tends to be of limited use in practice. There is a demand for developing and studying multivariate models with any pre-specified bivariate margins.

Suppose there exists such a class of flexible models with any pre-specified bivariate margins. Given a multivariate data, what is the distribution function and how to easily estimate the parameters …

Investigation Of Topological Phonons In Discrete Mechanical Metamaterials, Kai Qian

Dissertations

The study of topological mechanical metamaterials is a new emerging field that focuses on the topological properties of artificial mechanical structures. Inspired by topological insulators, topological mechanism has attracted intensive attention in condensed matter physics and successfully connected the quantum mechanical descriptions of electrons with the classical descriptions of phonons. It has led to experiments of mechanical metamaterials possessing topological characteristics, such as topologically protected conducting edges or surfaces without back-scattering. This dissertation presents a new experimental approach for mechanically engineering topological metamaterials based on patterning magnetically coupled spinners in order to localize the propagation of vibrations and evaluate different …

An Examination Of Fontan Circulation Using Differential Equation Models And Numerical Methods, Vanessa Maybruck

Honors Student Research

Certain congenital heart defects can lead to the development of only a single pumping chamber, or ventricle, in the heart instead of the usual two ventricles. Individuals with this defect undergo a corrective, three-part surgery, the third step of which is the Fontan procedure, but as the patients age, their cardiovascular health will likely deteriorate. Using computational fluid dynamics and differential equations, Fontan circulation can be modeled to investigate why the procedure fails and how Fontan failure can be maximally prevented. Borrowing from well-established literature on RC circuits, the differential equation models simulate systemic blood flow in a piecewise, switch-like …

Assembly And Detection Of 3-D Qr Codes Through Additive Manufacturing And Terahertz Imaging, Patrick Dunn

Theses

Automatic identification and data capture, or AIDC, plays a substantial role in contemporary business, advertising, and military needs. The purpose of this study is to generate a potential alternative to current AIDC approaches by constructing three-dimensional plastic tags (or ‘3D QR codes’) using additive manufacturing techniques and interrogate them using Terahertz radiation. 3D Quick Response (QR) codes are designed in 3D computer-aided design software. The QR codes are 3D structures embedded in the printed plastic in which an air gap in the plastic (or an air gap filled in with another type of plastic) indicates a bit of information. Information …

Hydrodynamic Impacts Of Expanding Aquaculture, Zhilong Liu

Electronic Theses and Dissertations

Climate change may potentially change aquatic systems and bring certain risks for aquaculture development. Understanding interactions between aquaculture and the environment helps to ensure aquaculture expansion is sustainable in the future. It is critical to determine how farms influence tidal flow patterns, turbulence, mixing and material transport in estuaries. This research aims to determine the flow response of an oyster farm, predict how expanding farms and farm placement will alter estuarine dynamics, and understand how the design of a farm influences material transport.

The hydrodynamic response of a floating oyster aquaculture farm in a low inflow estuary (the Damariscotta River …

A Theoretical Study Of Synchronous Proton Transfer In (Hf)N, (H2O) N, And (Hcl) N Where N = 3, 4, 5, Johnny Yang

Honors Theses

For (HF)_n, (H₂O)_n, and (HCl)_n (n = 3 − 5), we have rigorously characterized the structures for the minima and transition states for synchronous proton transfer (SPT) with the CCSD(T) method and aug-cc-pVTZ basis set. The electronic barrier heights (∆E^†) associated with these transition states have also been computed with the explicitly correlated CCSD(T)-F12 method and the aug-cc-pVQZ-F12 basis set (abbreviated aQZ-F12). (HCl)_n (n = 3 − 5) SPT transition states have not been previously identified to the best of our knowledge, and they have been found …

Structural Dynamics Of Membrane Interacting Viral Proteins, Nisha Bhattarai

FIU Electronic Theses and Dissertations

Viruses do not possess complete cellular machinery but have the ability to reproduce by utilizing cellular machinery inside host cells. They are nanoscale machines that rapidly modify (evolve) their molecular components to cause disease and death. Therefore, emergence of deadly infectious viruses is a monumental health concern and understanding how viruses are able to enter, replicate, assemble and egress from the host cell is important to mitigate the threat.

A fully active, infectious viral structure is known as a virion. A virion contains genetic material and is enclosed by a capsid. The capsid is a protein shell and some viruses …

Theoretical Study On Η′ → Π+Π−Π+(0)Π−(0), Ehsan Jafari, Bing An Li

Physics and Astronomy Faculty Publications

The η′ meson is associated with the U(1) anomaly. In this paper, a successful effective chiral theory of mesons has been applied to study the anomalous decays of η′ → π⁺π⁻π⁺⁽⁰⁾π⁻⁽⁰⁾. Contribution of triangle and box diagrams is calculated, which indicates that the box anomaly has a significant contribution to the decay amplitudes.

[Please download the article to see the rest of the abstract.]

Can Parallel Gravitational Search Algorithm Effectively Choose Parameters For Photovoltaic Cell Current Voltage Characteristics?, Alan Kirkpatrick

Honors Projects

This study asks the question “Can parallel Gravitational Search Algorithm (GSA) effectively choose parameters for photovoltaic cell current voltage characteristics?” These parameters will be plugged into the Single Diode Model to create the IV curve. It will also investigate Particle Swarm Optimization (PSO) and a population based random search (PBRS) to see if GSA performs the search better and or more quickly than alternative algorithms

Evolution Of Magnetic Field Induced Ordering In The Layered Quantum Heisenberg Triangular-Lattice Antiferromagnet Ba3 Cosb2 O9, Nathanael Alexander Fortune, Q. Huang, T. Hong, J. Ma, E. S. Choi, Scott T. Hannahs, Z. Y. Zhao, X. F. Sun, Y. Takano, H. D. Zhou

Physics: Faculty Publications

Quantum fluctuations in the effective spin- 1/2 layered triangular-lattice quantum Heisenberg antiferromagnet Ba₃CoSb₂O₉ lift the classical degeneracy of the antiferromagnetic ground state in magnetic field, producing a series of novel spin structures for magnetic fields applied within the crystallographic ab plane, including a celebrated collinear “up-up-down” spin ordering with magnetization equal to 1/3 of the saturation magnetization over an extended field range. Theoretically unresolved, however, are the effects of interlayer antiferromagnetic coupling and transverse magnetic fields on the ground states of this system. Additional magnetic field induced phase transitions are theoretically expected and in some …

Beyond The Standard Models Of Particle Physics And Cosmology, Gabriele Rigo

Dissertations - ALL

Despite their numerous successes both from the theoretical and experimental point of view, conceptual and observational evidence suggests the Standard Models of Particle Physics and Cosmology should be considered incomplete theories, reliable only within their well-defined regime of validity. This dissertation covers various possible extensions of those models from the theoretical, phenomenological and model-building perspective. The topics analyzed range from extra-dimensional approaches to the hierarchy problem, to the AdS/CFT description of perturbative anomaly inflow, and new probes of vacuum energy in neutron stars and gravitational waves.

Optimization And Characterization Of Doped Optical Fibers For Radiation Balanced Fiber Laser And Amplifier, Mostafa Peysokhan

Optical Science and Engineering ETDs

Due to the reliability, compactness, low maintenance costs, superior performance, and versatility of fiber lasers and amplifiers, they are commonly employed in scientific and directed energy applications. Among all kinds of fiber lasers and amplifiers, high-power, Yb-dopped fiber lasers and amplifiers have been extensively researched to achieve higher output powers. One of the major hindrances to achieving higher powers with adequate stability and efficiency in high power performance is heat generated in the fiber lasers and amplifiers' core. The Radiation Balanced Laser (RBL) is a viable technique for heat mitigation has been proposed by S.~Bowman in 1995. RBL technique is …

Beyond The Standard Models Of Particle Physics And Cosmology, Gabriele Rigo

Dissertations - ALL

Despite their numerous successes both from the theoretical and experimental point of view, conceptual and observational evidence suggests the Standard Models of Particle Physics and Cosmology should be considered incomplete theories, reliable only within their well-defined regime of validity. This dissertation covers various possible extensions of those models from the theoretical, phenomenological and model-building perspective. The topics analyzed range from extra-dimensional approaches to the hierarchy problem, to the AdS/CFT description of perturbative anomaly inflow, and new probes of vacuum energy in neutron stars and gravitational waves.

Solid State Synthesis Of Polar Magnetic Oxides, Duy Pham

Symposium of Student Scholars

Non-centrosymmetric polar oxides are subjects of considerable interest due to varieties of important phenomena and associated functional properties. Magnetoelectric multiferroic oxides are one such system where the magnetic properties can be controlled by electric field or the electric properties can be controlled by the magnetic field. This cross tunability magnetic and electrical properties makes multiferroic materials ideal candidates for making actuators, field sensors and memory devices. Simultaneous presence of broken inversion symmetry (electric polarization) and magnetism are two key requirements for multiferroicity. Non-centrosymmetric polar magnetic oxides simultaneously offer both (polarization and magnetization) properties. Therefore, we are working toward synthesis and …

Control-Oriented Nonlinear Modeling Of Polyvinyl Chloride (Pvc) Gel Actuators, Mohammed Al-Rubaiai, Xinda Qi, Zachary Frank, Ryohei Tsuruta, Umesh Gandhi, Kwang J. Kim, Xiaobo Tan

Mechanical Engineering Faculty Research

Polyvinyl chloride (PVC) gel-based actuators are a new class of soft, electroactive polymer actuators with several attractive properties, including low cost, large compliance, large strain output, high-stress output, fast response, and stability against thermal influence. While PVC gel actuators are quickly gaining attention, they remain largely unexplored despite their great potential in a long list of applications compared with many other smart material actuators. In particular, little work has been reported on modeling nonlinear dynamics of PVC actuators. In this work a nonlinear, control-oriented Hammerstein model, with a polynomial nonlinearity preceding a transfer function, is proposed to capture the amplitude-dependent …

Development Of A Diamond Defect Quantum Sensing Platform For Probing Novel Quantum Magnetic Phases, Jeffrey Ahlers

Senior Honors Papers / Undergraduate Theses

Nitrogen vacancy centers in diamond are highly effective quantum sensors due to their high spatial resolution and high magnetic field sensitivity. We present the construction of an optically detected magnetic resonance platform in order to facilitate the probing of magnetic phases in two-dimensional heterostructures. This includes the characterization of the required microwave voltage controlled oscillator and amplifier. In the presence of crystal strain, we measure ensemble nitrogen vacancy spin transitions with and without an applied magnetic field, and observe frequency shifts consistent with sample heating.

Electrochemical And Spectroscopic Characterization Of Cerium Salts And Nanoceria Material, Emily Velarde, Wei Zhou

Symposium of Student Scholars

The nanoscale form of cerium oxide, nanoceria (nano-CeO_x), has drawn great attention in recent years in electrochemical, nanomaterial research and medicinal studies due to its antibacterial properties, UV absorption, and its biochemical function as possible radical scavenger. Many new synthesis methods have achieved uniform and biocompatible nanoceria particles, and our lab has created cerium oxide particles that shows UV/Vis. absorption and X-ray patterns similar to the commercial nanoceria and nanoceria made in other research laboratories with novel synthetic methods.

This study focuses on charactering and comparing electrochemical properties of cerium inorganic salts and synthesized nanoceria. Preliminary results …

Development And Implementation Of A Pressure-Temperature Control System For The Physical Vapor Deposition Of Copper And Niobium From A Molybdenum Filament In The Development Of Superconducting 3d Printed Rf Cavity Particle Accelerators, Chandler J. Fleuette

Student Research Projects

This report covers the development of the pressure-temperature control system used in the production of small superconducting RF cavities for particle accelerators. To test the validity of the created program, a model for the process was created and tested. The model was used to fine tune the control system before integrating it into the lab. The end goal of the control system is to measure the pressure inside of a deposition vacuum chamber, convert that pressure to a temperature, and use that temperature in tandem with a PID controller to control the current passing though a molybdenum filament which is …

Photoemission Electron Microscopy For Direct Observation Of Photonic And Plasmonic Phenomena, Theodore Stenmark

Dissertations and Theses

Photoemission electron microscopy (PEEM) is a high-resolution microscopy technique that collects photoemitted electrons from the sample surface to form an image. PEEM offers a non-scanning imaging method with a spatial resolution in the range of 5-100nm by combining the advantages of light excitation and electron imaging. Our work looks at PEEM as an analysis tool for photonic and plasmonic phenomena. Photonic wave guiding structures exhibiting a strong dispersion relation have attracted considerable attention for applications in integrated optics, communications and sensing devices. Line defects in a photonic crystal (PC) slab offer a highly efficient way to create light with group …

Semiclassical Theory Of Laser-Assisted Dissociative Recombination, Ilya I. Fabrikant, H. B. Ambalampitiya, I. F. Schneider

Department of Physics and Astronomy: Faculty Publications

We study the process of laser-assisted dissociative recombination of an electron with a molecular cation using a semiclassical approach. In the region outside a reaction sphere the electron motion in the combined laser and Coulomb fields is treated classically. Within the sphere the laser-field effects are neglected, and the recombination probability is obtained from quantum-mechanical cross sections calculated for the laser-free process. Specific calculations are performed for dissociative recombination of H₂⁺ in the field of the intensity 2.09 GW/cm² and the wavelength 22.8 μm. In the energy region above 1 meV the cross section is significantly …

Population Properties Of Compact Objects From The Second Ligo-Virgo Gravitational-Wave Transient Catalog, R. Abbott, T. D. Abbott, Marco Cavaglia, For Full List Of Authors, See Publisher's Website.

Physics Faculty Research & Creative Works

We report on the population of 47 compact binary mergers detected with a false-alarm rate of < 1 yr^-1 in the second LIGO-Virgo Gravitational-Wave Transient Catalog. We observe several characteristics of the merging binary black hole (BBH) population not discernible until now. First, the primary mass spectrum contains structure beyond a power law with a sharp high-mass cutoff; it is more consistent with a broken power law with a break at 39.7^+20.3_-9.1 M_⊙ or a power law with a Gaussian feature peaking at 33.1^+4.0_-5.6 M_⊙ (90% credible interval). While the primary mass distribution must extend to …

Validation Of A Respiratory Gating System For Automated Delivery Of The Deep Inspiration Breath-Hold Technique, Michael G. Stock

LSU Master's Theses

Purpose: To validate the performance of a respiratory gating system for the automated delivery of the deep inspiration breath-hold (DIBH) technique.

Methods: The gating system utilized an automatic gating interface (Elekta Response) which connected a marker-based respiratory motion monitoring system to the linear accelerator control system. The gating system was characterized dosimetrically and temporally using two distinct approaches. Central-axis output and energy constancy were evaluated across 8 beam-matched linear accelerators. Additionally, a representative set of 5 treatment plans were delivered both non-gated and gated to a 2D diode array (MapCHECK). The respiratory motion monitoring system optically tracked a reflective marker …

A New Method To Generate Superoscillating Functions And Supershifts, Yakir Aharonov, Fabrizio Colombo, Irene Sabadini, Tomer Shushi, Daniele C. Struppa, Jeff Tollaksen

Mathematics, Physics, and Computer Science Faculty Articles and Research

Superoscillations are band-limited functions that can oscillate faster than their fastest Fourier component. These functions (or sequences) appear in weak values in quantum mechanics and in many fields of science and technology such as optics, signal processing and antenna theory. In this paper, we introduce a new method to generate superoscillatory functions that allows us to construct explicitly a very large class of superoscillatory functions.

Population Properties Of Compact Objects From The Second Ligo–Virgo Gravitational-Wave Transient Catalog, R. Abbott, T. D. Abbott, S. Abraham, Ofek Birnholtz, F. Acernese, Teviet Creighton, Soma Mukherjee, Volker Quetschke, Malik Rakhmanov, Karla E. Ramirez, W. H. Wang

Physics and Astronomy Faculty Publications and Presentations

We report on the population of 47 compact binary mergers detected with a false-alarm rate of < in the second LIGO–Virgo Gravitational-Wave Transient Catalog. We observe several characteristics of the merging binary black hole (BBH) population not discernible until now. First, the primary mass spectrum contains structure beyond a power law with a sharp high-mass cutoff; it is more consistent with a broken power law with a break at or a power law with a Gaussian feature peaking at (90% credible interval). While the primary mass distribution must extend to or beyond, only of systems have primary masses greater than . Second, we find that a fraction of BBH systems have component spins misaligned with the orbital angular momentum, giving rise to precession of the orbital plane. Moreover, %–% of BBH systems have spins tilted by more than 90°, giving rise to a negative effective inspiral spin parameter, . Under the assumption that such systems can only be formed by dynamical interactions, we infer that between 25% and 93% of BBHs with nonvanishing are dynamically assembled. Third, we estimate merger rates, finding for BBHs and for binary neutron stars. We find that the BBH rate likely increases with redshift ( credibility) but not faster than the star formation rate ( credibility). Additionally, we examine recent exceptional events in the context of our population models, finding that the asymmetric masses of GW190412 and the high component masses of GW190521 are consistent with our models, but the low secondary mass of GW190814 makes it an outlier.

Characterization Of Landslide Processes From Radar Remote Sensing And Hydromechanical Modeling, Yuankun Xu

Earth Sciences Theses and Dissertations

Landsides are a natural geomorphic process yet a dangerous hazard which annually causes thousands of casualties and billions of property loss in a global scale. Understanding landslide motion kinematics from early initiation to final deposition is critical for monitoring, assessing, and forecasting landslide movement in order to mitigate their hazards. Landslides occur under diverse environmental settings and appear in variable types; however, all types of landslides can be mechanically attributed to shearing failure at the basal surface due to stress regime shift contributed by internal and/or external forcing. Typical internal factors include soil/rock weathering, whereas typical external triggering forces encompass …

Supernova Neutrino Burst Detection With The Deep Underground Neutrino Experiment, B. Abi, R. Acciarri, M. A. Acero, G. Adamov, D. Adams, M. Adinolfi, Z. Ahmad, J. Ahmed, T. Alion, S. Alonso Monslave, C. Alt, J. Anderson, C. Andreopoulos, M. P. Andrews, F. Andrianala, S. Andringa, A. Ankowski, M. Antonova, S. Antusch, A. Aranda-Fernadez, Roberto Petti

Faculty Publications

The Deep Underground Neutrino Experiment (DUNE), a 40-kton underground liquid argon time projection chamber experiment, will be sensitive to the electronneutrino flavor component of the burst of neutrinos expected from the next Galactic core-collapse supernova. Such an observation will bring unique insight into the astrophysics of core collapse as well as into the properties of neutrinos. The general capabilities of DUNE for neutrino detection in the relevant few- to few-tens-of-MeV neutrino energy range will be described. As an example, DUNE’s ability to constrain the ν_e spectral parameters of the neutrino burst will be considered.

Computational Design Of Two-Dimensional Transition Metal Dichalcogenide Alloys And Their Applications, John Douglas Cavin

Arts & Sciences Electronic Theses and Dissertations

The discovery of bronze as an alloy of copper and tin is arguably the earliest form of material design, dating back thousands of years. In contrast, two-dimensional materials are new to the 21st century. The research presented in this dissertation is at the intersection of alloying and two-dimensional materials. I specifically study a class of two-dimensional materials known as transition metal dichalcogenides (TMDCs). Because of the large number of transition metals, there are many combinations of TMDCs that can be alloyed, making experimental exploration of the phase space of possible alloys unwieldly. Instead, I have applied first-principles methods to study …

Assessment And Diagnosis Of Human Colorectal And Ovarian Cancer Using Optical Imaging And Computer-Aided Diagnosis, Yifeng Zeng

McKelvey School of Engineering Theses & Dissertations

Tissue optical scattering has recently emerged as an important diagnosis parameter associated with early tumor development and progression. To characterize the differences between benign and malignant colorectal tissues, we have created an automated optical scattering coefficient mapping algorithm using an optical coherence tomography (OCT) system. A novel feature called the angular spectrum index quantifies the scattering coefficient distribution. In addition to scattering, subsurface morphological changes are also associated with the development of colorectal cancer. We have observed a specific mucosa structure indicating normal human colorectal tissue, and have developed a real-time pattern recognition neural network to localize this specific structure …

Partial Measurements Of Quantum Systems, Jonathan Tyler Monroe

Arts & Sciences Electronic Theses and Dissertations

Projective measurement is a commonly used assumption in quantum mechanics. However, advances in quantum measurement techniques allow for partial measurements, which accurately estimate state information while keeping the wavefunction intact. We employ partial measurements to study two phenomena. First, we investigate an uncertainty relation—in the style of Heisenberg’s 1929 thought experiment—which includes partial measurements in addition to projective measurements. We find that a weak partial measurement can decrease the uncertainty between two incompatible (non-commuting) observables. In the second study, we investigate the foundation of irreversible dynamics resulting from partial measurements. We do so by comparing the forward and time-reversed probabilities …