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Articles 31 - 60 of 83
Full-Text Articles in Physical Sciences and Mathematics
Acoustic Radiation Force On A Fluid To Fluid Boundary By Phase Plate Focused Ultrasound, Robert Lee Lirette
Acoustic Radiation Force On A Fluid To Fluid Boundary By Phase Plate Focused Ultrasound, Robert Lee Lirette
Electronic Theses and Dissertations
In this study, the physics and applications of the ultrasonic radiation force at the interface between two immiscible fluids were investigated. These studies were performed using low-profile discrete-stepped lenses to the modify the phase of the incident radiation generating multiple field morphologies. In its first application to acoustics, a fraxicon lens was developed to approximate the field generated by an axicon. This type of lens creates a minimally diffractive Bessel beam and long depth of focus that is useful in ultrasonic imaging, therapy, and non-destructive evaluation techniques. Fields modified by fraxicon, Fresnel, and axicon lenses were characterized experimentally by scanning …
Investigation Of Narrow Bipolar Events In Mississippi Thunderstorms, Sampath Asiri Bandara
Investigation Of Narrow Bipolar Events In Mississippi Thunderstorms, Sampath Asiri Bandara
Electronic Theses and Dissertations
In the first part of the study FA and Log-RF data were used to examine low-altitude (<8.0 km) negative NBEs (NNBEs) to see how many -CG flashes were initiated by NNBEs. Out of 686 -CG flashes only 33 (5%) flashes were initiated by an NNBE. These NNBEs occurred at an average altitude of 6.2 km had average amplitude (range-normalized amplitude to 100 km) of 0.4 V/m and had average VHF (Log-RF) power of 130 W. Since the low-altitude NNBEs were substantially weaker than positive NBEs that initiate intracloud (IC) flashes it is hypothesized that -CG flashes are easier to initiate than IC flashes. The second part of the study investigated the properties of 201 positive NBEs (+NBEs). The +NBEs were classified in two ways: into Types A-D [Karunarathne et al. 2015] and into three different groups: Isolated Not-isolated and IC flash-initiator or INBE [Wu et al. 2014]. The average VHF (Log-RF) power of NBEs within the A-D categories were 1.9 4 9.8 and 13.2 kW respectively while the powers for the Isolated Not-isolated and INBE categories were 10.1 4 and 10.1 kW respectively. The third study considered 34 NBEs that occurred close in space and time to each other: 13 pairs of NBEs one group of three +NBEs and one group of five +NBEs. The NBEs were overlaid on radar data of the parent thunderstorms. The data indicate that the individual NBEs in each group initiated in separate intense electric field regions of small extent rather than in a single large-scale electric field region. This dissertation investigates Narrow Bipolar Events (NBEs) which are a type of short-duration (10- 30 µs) lightning discharge. The study primarily used data from NBEs collected in 2016 at seven sensor sites within 50 km of Oxford Mississippi USA. Each sensor site had three electromagnetic antennas called Fast Antenna (FA) dE⁄dt and Log-RF with bandwidths of 0-2.5 MHz 0-1.0 MHz and 186-192 MHz respectively. NBEs are often isolated from other lightning events in thunderclouds but they sometimes initiate negative cloud-to-ground (-CG) and intracloud (IC) lightning flashes or they can occur during these flashes.
Frequency And Temperature Dependence Of Shear Wave Speed With Rheological Properties In A Micellar Fluid, E. G. Sunethra K. Dayavansha
Frequency And Temperature Dependence Of Shear Wave Speed With Rheological Properties In A Micellar Fluid, E. G. Sunethra K. Dayavansha
Electronic Theses and Dissertations
Wormlike micellar fluids, which flow when subjected to long-term stresses, are mechanically viscoelastic over shorter durations and can support shear waves. These fluids are birefringent under shear, allowing the study of shear wave propagation using both optical and acoustic modalities. Microstructural phase transitions of the micelles are temperature dependent and can manifest as sharp changes in the shear wave speed as a function of temperature. In this work, the behavior of shear waves in a fluid consisting of hexadecyltrimethylammonium bromide (CTAB) and sodium salicylate (NaSal) combined in a 5:3 ratio in a 200 mM concentration is studied. The temperature-dependent microstructural …
Experimental Investigation Of Impurities And Their Effect On Acousto-Electric Properties Of Lithium Niobate, Chandrima Chatterjee
Experimental Investigation Of Impurities And Their Effect On Acousto-Electric Properties Of Lithium Niobate, Chandrima Chatterjee
Electronic Theses and Dissertations
No abstract provided.
The Beam Dynamics And Beam Related Uncertainties In Fermilab Muon G-2 Experiment, Wanwei Wu
The Beam Dynamics And Beam Related Uncertainties In Fermilab Muon G-2 Experiment, Wanwei Wu
Electronic Theses and Dissertations
The anomaly of the muon magnetic moment, aμ ≡ (g-2)/2, has played an important role in constraining physics beyond the Standard Model for many years. Currently, the Standard Model prediction for aμ is accurate to 0.42 parts per million (ppm). The most recent muon g-2 experiment was done at Brookhaven National Laboratory (BNL) and determined aμ to 0.54 ppm, with a central value that differs from the Standard Model prediction by 3.3-3.6 standard deviations and provides a strong hint of new physics. The Fermilab Muon g-2 Experiment has a goal to measure aμ to unprecedented precision: 0.14 ppm, which could …
Effective Interactions Between Local Hopping Modulations On The Square Lattice, Huu T. Do
Effective Interactions Between Local Hopping Modulations On The Square Lattice, Huu T. Do
Electronic Theses and Dissertations
No abstract provided.
Design Of A High Luminosity 100 Tev Proton Antiproton Collider, Sandra Jimena Oliveros Tautiva
Design Of A High Luminosity 100 Tev Proton Antiproton Collider, Sandra Jimena Oliveros Tautiva
Electronic Theses and Dissertations
Currently new physics is being explored with the Large Hadron Collider at CERN and with Intensity Frontier programs at Fermilab and KEK. The energy scale for new physics is known to be in the multi-TeV range, signaling the need for a future collider which well surpasses this energy scale. A 10 34 cm-2 s-1 luminosity 100 TeV proton-antiproton collider is explored with 7× the energy of the LHC. The dipoles are 4.5 T to reduce cost. A proton-antiproton collider is selected as a future machine for several reasons. The cross section for many high mass states is 10 times higher …
Compact Objects In Relativistic Theories Of Gravity, Hector Okada Da Silva
Compact Objects In Relativistic Theories Of Gravity, Hector Okada Da Silva
Electronic Theses and Dissertations
In this dissertation we discuss several aspects of compact objects, i.e. neutron stars and black holes, in relativistic theories of gravity. We start by studying the role of nuclear physics (encoded in the so-called equation of state) in determining the properties of neutron stars in general relativity. We show that low-mass neutron stars are potentially useful astrophysical laboratories that can be used to constrain the properties of the equation of state. More specifically, we show that various bulk properties of these objects, such as their quadrupole moment and tidal deformability, are tightly correlated. Next, we develop a formalism that aims …
Final Muon Cooling For A Muon Collider, John Gabriel Acosta Castillo
Final Muon Cooling For A Muon Collider, John Gabriel Acosta Castillo
Electronic Theses and Dissertations
To explore the new energy frontier, a new generation of particle accelerators is needed. Muon colliders are a promising alternative if muon cooling can be made to work. Muons are 200 times heavier than electrons, so they produce less synchrotron radiation, and they behave like point particles. However, they have a short lifetime of 2.2 μs and the beam is more difficult to cool than an electron beam. The Muon Accelerator Program (MAP) was created to develop concepts and technologies required by a muon collider. An important effort has been made in the program to design and optimize a muon …
Searching For New Physics In The B-Quark’S And Higgs’ Sectors Via Kinematic And Angular Distributions, Shanmuka Shivashankara
Searching For New Physics In The B-Quark’S And Higgs’ Sectors Via Kinematic And Angular Distributions, Shanmuka Shivashankara
Electronic Theses and Dissertations
The kinematic and angular distributions are calculated for the decay Λ b → Λclν l. Deviations from the standard model are expected given the apparent lepton flavor violation in the process B → D(*)+ τ – ντ. Including these measured deviations from the SM, the upper and lower bounds for R Λb = B(Λ b → Λcτ ντ) / B(Λ b → Λcl νl) are calculated along with other observables for a variety of new physics Lorentz structures. Distributions are also calculated for H → W –W+*(or H +*) → τ–ν ττ+ντ via Type II and leptophilic 2HDM’s. Although, the …
Low-Frequency Emission Enhancement By Resonant Acoustic Metamaterials, Maryam Landi
Low-Frequency Emission Enhancement By Resonant Acoustic Metamaterials, Maryam Landi
Electronic Theses and Dissertations
Omnidirectional and directional acoustic emission enhancements, at low frequencies as well as broad frequency bands, are highly demanded in audio, medical ultrasonics, and underwater acoustics. Emission enhancement and controlling the directivity of an acoustic source is however restricted to the properties of the source. In particular, the size of the source, in comparison with the wavelength of the sound, plays a very dominant role in determining the quality of the emitted acoustic wave. Most problems arise when there is a small acoustic source emitting very low frequency sound with large wavelength. Prior studies have proposed several solutions to this problem …
Measurement Of The Verdet Constant For A Previously Uncharacterized Fused Quartz Glass, Samyukta Krishnamurthy
Measurement Of The Verdet Constant For A Previously Uncharacterized Fused Quartz Glass, Samyukta Krishnamurthy
Honors Theses
The objective of this experiment is to measure and analyze the Verdet constant for Corning 7980, a fused quartz glass with no previously published Verdet constant data. This quartz glass is being used at the Belle II experiment at Tsukuba, Japan. The Verdet constant is measured using the Faraday effect — a magneto-optical phenomenon that describes the rotation of the plane of polarization of light within a medium in the presence of an external magnetic field. This experiment quantifies the rotation of the plane of polarization with respect to the wavelength and the magnetic field. Data collected through this experiment …
A Thermal Enclosure Prototype For A Suspended Inertial Sensor, Mohammad Afrough
A Thermal Enclosure Prototype For A Suspended Inertial Sensor, Mohammad Afrough
Electronic Theses and Dissertations
Although Ligo has detected six gravitational waves so far, people are still conducting research to improve the sensitivity of the detectors in different aspects. At low frequency band, one of the main sources of noise is seismic vibration. Lowering the noise level in this band, helps us to follow the coalescence of compact binary systems earlier in their transformation and increase the signal-to-noise ratio. It also allows us to detect merger of more massive objects. Hence, an isolation system is required to reduce the seismic noise. As a part of isolation system (which can be a passive or an active …
Temperature And Pressure Effects On Elastic Properties Of Relaxor Ferroelectrics And Thermoelectrics: A Resonant Ultrasound Spectroscopy Study, Sumudu Tennakoon
Temperature And Pressure Effects On Elastic Properties Of Relaxor Ferroelectrics And Thermoelectrics: A Resonant Ultrasound Spectroscopy Study, Sumudu Tennakoon
Electronic Theses and Dissertations
Relaxor ferroelectric lead magnesium niobate-lead titanate (PMN-PT) material exhibits exceptional electromechanical properties. The material undergoes a series of structural phase transitions with changes in temperature and the chemical composition. The work covered in this dissertation seek to gain insight into the phase diagram of PMN-PT using temperature and pressure dependence of the elastic properties. Single crystal PMN-PT with a composition near morphotropic phase boundary (MPB) was investigated using a resonant ultrasound spectroscopy (RUS) methodologies in the temperature range of 293 K - 800 K and the pressure range from near vacuum to 3.4 MPa. At atmospheric pressure, significantly high acoustic …
Computation Of Acoustic Ressure Fields Produced In Feline Brain By High-Intensity Focused Ultrasound, Nazanin Omidi
Computation Of Acoustic Ressure Fields Produced In Feline Brain By High-Intensity Focused Ultrasound, Nazanin Omidi
Electronic Theses and Dissertations
In 1975, Dunn et al. (Jasa 58:512-514) shothat a simple relation describes the ultrasonic threshold for cavitation induced changes in the mammalian brain. The thresholds for tissue damage were estimated for a variety of acoustic parameters in exposed feline brain. The goal of this study was to improve the estimates for acoustic pressures and intensities present in vivo during those experimental exposures by estimating them using nonlinear rather than linear theory. In our current project, the acoustic pressure waveforms produced in the brains of anesthetized felines were numerically simulated for a spherically focused, nominally f1-transducer (focal length = 13 cm) …
A Study On The Characterization And Implementation Of Tools For Advanced Ligo, Hunter Gabbard
A Study On The Characterization And Implementation Of Tools For Advanced Ligo, Hunter Gabbard
Honors Theses
The Laser Interferometer Gravitational Wave Observatory (LIGO) is aimed at directly detecting gravitational waves, small perturbations or ripples in the fabric of space-time. Because of their extreme sensitivity, the LIGO detectors are affected by many sources of non-astrophysical noise. In the first part of this thesis we test a pipeline designed for the identification of short-duration noise transients, called Omicron. We first inject simulated noise waveforms in engineering run data from the LIGO detector in Livingston, Louisiana and then determine Omicron efficiency by attempting to recover these injections. In the second part of this thesis, we present a novel method …
Blue Cheese Cosmology: Lensing By Cosmic Strings, Jared Wofford
Blue Cheese Cosmology: Lensing By Cosmic Strings, Jared Wofford
Honors Theses
The light bending effects around cosmic strings in universes with varying rates of expansion are investigated. A relationship between the angular deflection and the expansion rate is found. This is made possible by the Blue Cheese model, which is a generalization to a cylindrical realm of the Swiss Cheese model
Multidimensional Motion Capture Using Doppler Ultrasound, Forrest Nolan Gamble
Multidimensional Motion Capture Using Doppler Ultrasound, Forrest Nolan Gamble
Honors Theses
Ultrasonic waves are used to measure the velocity of a target object by measuring the Doppler shift of the reflected waves. In this work, ultrasonic Doppler Sonar (UDS) was used to measure the velocity of objects, including a pendulum and a battery on a turntable. The investigation focused on developing a method to measure motion in two and three dimensions, for applications in gait analysis and sports motion capture. By using multiple ultrasonic transducers and novel data processing techniques, the UDS captured motion in two and three dimensions. In order to test the accuracy of the velocity and position measurements, …
Calculating Liquefaction Potential Of Northern Mississippi Using Shear Wave Data, Peshani Herath
Calculating Liquefaction Potential Of Northern Mississippi Using Shear Wave Data, Peshani Herath
Honors Theses
The potential for liquefaction can be determined using the Liquefaction Potential Index (LPI). The LPI takes into account the thickness of the liquefiable layers and the factors of safety with respect to depth. This study creates a hybrid method for determining the LPI for different locations in Northern Mississippi. It calculates an average CSR for the region using existing borehole information. The CRR is then calculated using shear wave velocity profile data from a MASW survey. The LPI obtained from this process is compared to LPI values calculated using CPT data and borehole shear wave data. Surface shear wave velocity …
Noise Reduction In The Manufacturing Environment: A Study On Small Jet Geometry Alterations, Shawn Wesley Skinner
Noise Reduction In The Manufacturing Environment: A Study On Small Jet Geometry Alterations, Shawn Wesley Skinner
Honors Theses
Noise pollution is an identified issue in manufacturing environments. While machines, motion, production, etc. are a large factor in this noise pollution, other sources exist. Often copper tubing is connected to pressurized containers as a make-shift jet stream for reorienting elements on the assembly line. These makeshift jets when working in conjunction create noise pollution. By manipulating the exit of these small jets, it is hypothesized that the noise level can be decreased. Using the National Center for Physical Acoustics (NCPA) at the University of Mississippi, three geometry alterations—deburring the end, creating a converging-diverging nozzle, and flattening the end—were tested …
Semi-Leptonic Decay Of Lambda-B In The Standard Model And With New Physics, Wanwei Wu
Semi-Leptonic Decay Of Lambda-B In The Standard Model And With New Physics, Wanwei Wu
Electronic Theses and Dissertations
Heavy quark decays provide a very advantageous investigation to test the Standard Model (SM). Recently, promising experiments with b quark, as well as the analysis of the huge data sets produced at the B factories, have led to an increasing study and sensitive measurements of relative b quark decays. In this thesis, I calculate various observables in the semi-leptonic decay process Λb → Λ cτν[special character omitted]τ both in the SM and in the presence of New Physics (NP) operators with different Lorentz structures. The results are relevant for the coming measurement of this semi-leptonic decay at LHC b experiment …
Wind Induced Ground Motion, Vahid Naderyan
Wind Induced Ground Motion, Vahid Naderyan
Electronic Theses and Dissertations
Wind noise is a problem in seismic surveys and can mask the seismic signals at low frequency. Development of practical solutions to this problem must be based on a good understanding of the mechanism of the wind-ground coupling. This thesis investigates the driving pressure and shear stress perturbations on the ground surface associated with wind-induced ground motions. A prediction of the ground displacements spectra from the measured ground properties and predicted pressure and shear stress at the ground surface is developed. Field measurements are conducted at a site in Marks, MS, having a flat terrain and low ambient seismic noise …
Acousto-Electric Impedance Of Ferroelectric Phononic Superlattice, Ola Hassan Nusierat
Acousto-Electric Impedance Of Ferroelectric Phononic Superlattice, Ola Hassan Nusierat
Electronic Theses and Dissertations
The Acousto-Electric Impedance z of a Ferroelectric Phononic Superlattice (fps) is investigated. The analytical derivation of z and its phase reveal that both are functions of physical parameters such as the electromechanical coupling coefficient, the mechanical quality factor, the domain length and the phase velocity of the plate acoustic waves (paw). Mathematical code is produced that allows for modeling z in a two dimensional fps. It is observed that z depends on the number of domains in the fps structure. Fewer domains in the structure might minimize z or make it approach zero at certain conditions. A series of experiments …
Biomolecular Folding Rates As Understood From Single-Reaction-Coordinate Langevin Dynamics And Kramers’ Theory, Md Adnan Kabir
Biomolecular Folding Rates As Understood From Single-Reaction-Coordinate Langevin Dynamics And Kramers’ Theory, Md Adnan Kabir
Electronic Theses and Dissertations
Langevin dynamics was used to model the folding and unfolding of simple, hairpin-like biomolecules whose ends are attached to laser-trapped beads, as occurs in optical tweezers experiments. The Langevin process was evolved numerically, using parameters motivated by real experimental systems. Folding trajectories were generated and analyzed to extract the folding rate as a function of the force applied to the beads. The observed rate was compared to the analytical predictions of Kramers' theory. Strong discrepancies were noted. The failure of the Kramers' theory was attributed to the slow dynamical response of the beads, which it does not account for. The …
Testing Lepton Nonuniversality In Tau Neutrino Scattering, Hongkai Liu
Testing Lepton Nonuniversality In Tau Neutrino Scattering, Hongkai Liu
Electronic Theses and Dissertations
Recently hints of lepton flavor non-universality emerged in the BaBar and LHCb experiments. In this paper we propose tests of lepton universality in scattering. To parametrize the new physics we adopt an effective Lagrangian approach and consider the neutrino deep inelastic scattering processes tau neutrino+nucleon to tau + X and muon neutrino+nucleon to muon + X where we assume the largest new physics effects are in the tau sector. We also consider an explicit leptoquark model in our calculations. In order to make comparison with the standard model and also in order to cancel out the uncertainty of the parton …
Fscan Code Development For Advanced Ligo Detector Characterization, Cody Arceneaux
Fscan Code Development For Advanced Ligo Detector Characterization, Cody Arceneaux
Electronic Theses and Dissertations
The Advanced Laser Interferometer Gravitational-wave Observatory (LIGO) is an experiment designed to provide direct detection of gravitational waves. Its searches for periodic gravitational waves are highly susceptible to long-duration noise that appears as spectral lines. FScan is a tool for finding spectral lines and is used to identify the lines that appear in the gravitational-wave data; it is also used to characterize LIGO's detectors. This thesis details work in rewriting the plotting portion of FScan, making improvements to the FScan driver script, and writing code to assist in the tracking of wandering spectral lines. In particular, this thesis presents the …
Visualization Techniques Of Shear Wave Propagation In Wormlike Micellar Fluid, Connor M. Tierney
Visualization Techniques Of Shear Wave Propagation In Wormlike Micellar Fluid, Connor M. Tierney
Honors Theses
In an aqueous solution amphiphilic molecules can self-aggregate and form a wormlike micellar fluid. These non-Newtonian fluids have been studied in the context of diagnostic medical imaging due to the fact that the fluids have viscoelastic properties and can act as a nonperishable model for human tissue. They also display flow-birefringence, which is a property that allows for the analysis of shear wave propagation through the fluid. However, one issue encountered at lower micelle concentrations is the inability to see the emergent birefringence pattern that results from shear wave propagation. In this study Experiment 1 was an analysis of shear …
Comparison Of The Spatial Distributions Of Cavitation Damage With The Measured Diffraction Patterns For A High-Power Ultrasonic Transducer, Davis Lane Rogers
Comparison Of The Spatial Distributions Of Cavitation Damage With The Measured Diffraction Patterns For A High-Power Ultrasonic Transducer, Davis Lane Rogers
Honors Theses
The purpose of this study was to evaluate the performance of a model of the propagation of ultrasonic fields produced by an ultrasonic transducer, a device that uses a piezoelectric crystal to produce high-intensity ultrasonic waves. The transducer operates immersed in a water bath where it generates waves of sufficient intensity to produce non-linear phenomena that include acoustic streaming and cavitation. This study used a planar transducer to visualize the damaging effects of high-intensity ultrasonic waves targeted on acrylic plates. Seven plates were targeted and positioned from 8.5 to 11.5 cm from the transducer. The spatial distribution and degree of …
Wind Energy Harvesting Utilizing Biaxially Oriented Piezoelectric Polyvinylidenefluoride Film, Matthew Kennedy
Wind Energy Harvesting Utilizing Biaxially Oriented Piezoelectric Polyvinylidenefluoride Film, Matthew Kennedy
Honors Theses
With the growing concern over fossil fuels as a finite source of fuel and as a hazard to the environment, society has developed a growing interest in the use of renewable energy. Advancements in solar, nuclear, geothermal, wind, and vibrational energy harvesting, to name a few, have made the concept of using renewables as a main source of energy more feasible. The research and experimentation conducted for this thesis focused on analyzing the practicality of the future implementation of Biaxially Oriented Piezoelectric Polyvinylidenefluoride in the wind energy harvesting industry. The experiment consisted of data collection and analysis of power output …
Electron Cloud Studies With Transverse Beam Islands, Neetish Pradhan
Electron Cloud Studies With Transverse Beam Islands, Neetish Pradhan
Honors Theses
Electron cloud generation has been a rising problem in high energy beam chambers such as the LHC. In order to mitigate this problem, we looked for the best beam configuration to scrub the chambers and reduce its secondary electron yield. Using simulations, a five-island beam and a three-island beam were compared against a normal single beam. The five-island beam was found to work best.