Physics Commons^™

Diffractive Optical Elements With A Large Angle Of Operation Recorded In Acrylamide Based Photopolymer On Flexible Substrates, Hoda Akbari, Izabela Naydenova, Lina Persechini, Sean Garner, Pat Cimo, Suzanne Martin

Articles

A holographic device characterised by a large angular range of operation is under development. The aim of this study is to increase the angular working range of the diffractive lens by stacking three layers of high efficiency optical elements on top of each other so that light is collected (and focussed) from a broader range of angles. The angular range of each individual lens element is important, and work has already been done in an acrylamide-based photosensitive polymer to broaden the angular range of individual elements using holographic recording at a low spatial frequency.This paper reports new results on the …

Fragmentation And Wake Formation In Faint Meteors: Implications For The Structure And Ablation Of Small Meteoroids, Edward Stokan

Electronic Thesis and Dissertation Repository

Meteors with peak magnitudes fainter than +2 are typically called faint meteors, resulting from the atmospheric entry and ablation of meteoroids less massive than 10^-4 kg. The processes of luminous wake formation and fragmentation, which occur during ablation, are poorly understood for faint meteors, and are important constraints for models of meteoroid structure. The goal of this work is to improve understanding of these processes through analysis of high-resolution intensified video observations, and creation of a detailed meteoroid ablation model.

In the first part of this work, thirty faint meteors observed with the Canadian Automated Meteor Observatory (CAMO) are …

The Investigation Of Surplus Of Energy And Signal Propagation At Time-Domain Waveguide Modes, Özlem Işık, Zeynep F. Koçak, Emre Eroğlu

Applications and Applied Mathematics: An International Journal (AAM)

Classical waveguide theory has been developed bearing on Bernoulli’s product method which results in separation of space and time variables in Maxwell’s equations. The time-harmonic waveguide modes have been stated mathematically for transmitting signals along the waveguides. As a starting point, present studies on transverse-electric (TE) and transverse-magnetic (TM) waveguide modes with previous results are taken and exhibited in an advanced form. They have been obtained within the framework of an evolutionary approach to solve Maxwell’s equations with time derivative. As a result every modal field is obtained in the form of a product of vector functions of transverse coordinates …

Solution Of The Sir Models Of Epidemics Using Msgdtm, Asad A. Freihat, Ali H. Handam

Applications and Applied Mathematics: An International Journal (AAM)

Stochastic compartmental (e.g., SIR) models have proven useful for studying the epidemics of childhood diseases while taking into account the variability of the epidemic dynamics. Here, we use the multi-step generalized differential transform method (MSGDTM) to approximate the numerical solution of the SIR model and numerical simulations are presented graphically.

Confined Mesoscopic Fluid-Like Films Analyzed With Frequency Modulation And Acoustic Detection, Rodolfo Fernandez Rodriguez

Dissertations and Theses

Complete understanding of the physics underlying the changes in viscoelasticity, relaxation time, and phase transitions that mesoscopic fluid-like systems undergo at solid-liquid interfaces or under confinement remains one of the major challenges in condensed matter physics. Moreover, studies of confined mesoscopic fluid films are relevant to technological areas like adhesion, wetting processes and nanotribology.

This thesis addresses the interaction between two sliding solids interfaces separated by a nanometer sized gap, with emphasis on the role of the mesoscopic fluid film trapped between them. For this purpose we integrated two acoustic techniques, recently introduced by our group, into a sub-nanometer precision …

Non-Vacuum Ads Cosmologies And The Approach To Equilibrium Of Entanglement Entropy, Sebastian Fischetti, David Kastor, Jennie Traschen

David Kastor

We extend standard results for vacuum asymptotically locally AdS (AlAdS) spacetimes, showing that such spacetimes can be constructed as foliations where the induced metric on each hypersurface satisfies Einstein's equation with stress-energy. By an appropriate choice of stress-energy on the hypersurfaces, the resulting AlAdS spacetime satisfies Einstein's equation with a negative cosmological constant and physical stress tensor. We use this construction to obtain AlAdS solutions whose boundaries are FRW cosmologies sourced by a massless scalar field or by a perfect fluid obeying the strong energy condition. We focus on FRW universes that approach Minkowski spacetime at late times, yielding AlAdS …

A Potential Foundation For Emergent Space-Time, Kevin H. Knuth, Newshaw Bahreyni

Physics Faculty Scholarship

We present a novel derivation of both the Minkowski metric and Lorentz transformations from the consistent quantification of a causally ordered set of events with respect to an embedded observer. Unlike past derivations, which have relied on assumptions such as the existence of a 4-dimensional manifold, symmetries of space-time, or the constant speed of light, we demonstrate that these now familiar mathematics can be derived as the unique means to consistently quantify a network of events. This suggests that space-time need not be physical, but instead the mathematics of space and time emerges as the unique way in which an …

Detecting Corrosion Utilizing A Passive Rfid Tag, Emily Layden

Von Braun Symposium Student Posters

No abstract provided.

Physics: Rethinking The Foundations, Kevin H. Knuth

Physics Faculty Scholarship

Physics is traditionally conceived of as a set of laws that universally governs the behavior of physical systems. These laws, however they are decreed, are believed to govern the behavior of not only everything in the universe, but the form of the universe itself. However, this traditional concept of physics as a universal governance is at odds with our modern theories of quantum mechanics and relativity, which place the observer and information in a central role. In this talk, I aim to rethink the foundations and attempt to build physics from the bottom up based on a very simple foundational …

Sustainability Research Through The Lens Of Environmental Ethics, Daniel Clifford Fouke, Sukh Sidhu, Robert J. Brecha

Physics Faculty Publications

Two core courses in the curriculum of the University of Dayton’s Sustainability, Energy, and the Environment minor, Sustainability Research I and II, were developed out of the frustration one author, Daniel Fouke, experienced while teaching a traditional course on environmental ethics for the Department of Philosophy. The often-overwhelming nature of environmental problems tended to demoralize both the instructor and the students. Seeking a way to integrate ethical analysis of complex problems with the search for solutions, two courses were proposed that would be team-taught by a philosopher and a scientist or an engineer.

Development of the courses was initially funded …

Beam-Induced Radiation Heating On The Superconducting Undulator At The Advanced Photon Source, Laura Elizabeth Boon

Open Access Dissertations

In January 2013 the Advanced Photon Source (APS), a 7 GeV synchrotron X-ray source, commissioned a Superconducting Undulator (SCU). The superconducting magnet is thermally isolated from the beam vacuum chamber, which absorbs the beam-induced heating. Previous beam induced heat load studies at other laboratories had not included a robust calculation of radiation heating from the upstream dipole magnet. The mitigation of the radiation heating mechanism, and production of photoelectrons to seed an electron cloud was studied for this thesis. ^ An analytical model was developed to predict the radiation heat load on the SCU chamber. This model was benchmarked with …

Studies Of Angular Correlations Of Jets With The Atlas Detector, Rajivalochan Subramaniam

Doctoral Dissertations

The strong force is one of the four fundamental forces and its strength is given by the coupling constant αs. The theory that describes the strong interaction is Quantum Chromodynamics (QCD) and it explains the interactions between quarks and gluons. The strong coupling constant is the only free parameter in the QCD Lagrangian if the quark masses are fixed. Determinations of αs provide direct tests of perturbative QCD calculations. The collimated sprays of particles originating from the quark and gluon interactions are called jets. The ratio of jet cross sections are sensitive to α s and are …

Quantum Crystallography Of Hydronium Cations, Sonjae Sycoria Wallace

Dissertations, Theses, and Capstone Projects

Cationic hydronium clusters of the form [HaOb]^c,(c>0), have been investigated. After investigating over 2000 crystal structures containing hydronium cations found in the Cambridge Structural Database. The hydronium cationic compounds that were most unusual, mischaracterized, or those of apparent aggregates, were investigated further by geometry optimization and in some cases with the Quantum Theory of Atoms in Molecules (QTAIM). The results of our investigations yielded the first reports of stable conformations of cyclic dihydronium cationic clusters. In a second investigation we reported the first theoretically confirmed transition state of a H7O3+conformer captured within a crystal. A third product from our …

Gravity Wave Spectra Morphology In The Arctic And Non-Arctic Lower Atmosphere, Melanie C. Wright

Electronic Thesis and Dissertation Repository

The spectral analysis of data from three VHF radars (one high-Arctic and two mid-latitudes) show support for the universal spectrum theory for gravity waves in the lower atmosphere (altitudes of 2.0-11.0 km), provided that the impact of the off-vertical beam and noise are taken into consideration. This analysis also reveals that local gravity wave generation is of secondary importance, but still significant for determining the spectra.

A total of eight spectral methods were considered and scrutinized for the purposes of determining gravity wave spectra from VHF radar data. A definition for the “best” method was given and examined. The method …

Conservation Of The Spin And Orbital Angular Momenta In Electromagnetism, Konstantin Y. Bliokh, Justin Dressel, Franco Nori

Mathematics, Physics, and Computer Science Faculty Articles and Research

We review and re-examine the description and separation of the spin and orbital angular momenta (AM) of an electromagnetic field in free space. While the spin and orbital AM of light are not separately meaningful physical quantities in orthodox quantum mechanics or classical field theory, these quantities are routinely measured and used for applications in optics. A meaningful quantum description of the spin and orbital AM of light was recently provided by several authors, which describes separately conserved and measurable integral values of these quantities. However, the electromagnetic field theory still lacks corresponding locally conserved spin and orbital AM currents. …

Quantitative Assessment Of Blood Coagulation By Cold Atmospheric Plasma, Caitlin Heslin, Daniela Boehm, Vladimir Milosavljevic, Michelle Laycock, Patrick Cullen, Paula Bourke

Articles

Cold atmospheric plasma (CAP) is produced by ionizing a chosen gas, thereby creating charged and reactive species. The reactive species generated are capable of inducing a range of biomedically relevant interactions including blood coagulation. However, the underlying biochemical processes of plasma-assisted blood coagulation are largely unknown, and data quantifying blood clot formation or the impact of system parameters on the intensity of the blood clot are scarce. In this study, blood coagulation was quantified by measuring hemoglobin absorbance. System parameters of the kINPen plasma jet were investigated and compared, including treatment time, distance from the plasma source and gas flow …

Advances In Image Acquisition And Filtering For Mri Neuroimaging At 7 Tesla, Andrew T. Curtis

Electronic Thesis and Dissertation Repository

Performing magnetic resonance imaging at high magnetic field strength promises many improvements over low fields that are of direct benefit in functional neuroimaging. This includes the possibility of improved signal-to-noise levels, and increased BOLD functional contrast and spatial specificity. However, human MRI at 7T and above suffers from unique engineering challenges that limit the achievable gains. In this thesis, three technological developments are introduced, all of which address separate issues associated with functional magnetic resonance neuroimaging at very high magnetic field strengths.

First, the image homogeneity problem is addressed by investigating methods of RF shimming — modifying the excitation portion …

A Coordinated Investigation Of The Gravity Wavebreaking And The Associated Dynamicalinstability By A Na Lidar And An Advancedmesosphere Temperature Mapper Overlogan, Ut, Xuguang Cai

Xuguang Cai

No abstract provided.

Kinematic Effects In Large Transport Aircraft, Shem Malmquist, Dennis A. Vincenzi Ph.D., Dahai Liu Ph.D.

International Journal of Aviation, Aeronautics, and Aerospace

The control of an aircraft relies on sensory feedback. It follows that any aspect that could create a situation where that feedback is faulty can lead to unintended outcomes. The size of very large jet aircraft can result in kinematic effects that impact the perceptions of the flight crew. Due to the large amount of inertia involved, coupled with aerodynamic factors, when the aircraft pitch (θ) is initially changed, the short term actual motion of the aircraft, as viewed from the center of gravity, remains relatively unchanged. As a consequence of aircraft design, this results in the flight deck changing …

Quantitative Data Extraction Using Spatial Fourier Transform In Inversion Shear Interferometer, Yanzeng Li

Graduate Theses - Physics and Optical Engineering

Currently there are many interferometers used for testing wavefront, measuring the quality of optical elements, and detecting refractive index changes in a certain medium. Each interferometer has been constructed for a specific objective. Inversion shear interferometer is one of them. Compared to other interferometers, it has its own advantages, such as only being sensitive to coma aberration, but it has some limitations as well. It does not allow use of phase shifting technique. A novel inversion shear interferometer was invented using holographic lenses. By using the spatial carrier method, phase information of the wavefront was extracted. The breakthrough of the …

Volumetric Scintillation Dosimetry For Scanned Proton Beams, Daniel G. Robertson

Dissertations & Theses (Open Access)

Scanned beam proton therapy is a promising cancer treatment modality which is becoming more widely available with the increasing number of proton radiotherapy centers. Scanned proton beams can produce complex 3D dose distributions, presenting a challenge for adequate quality assurance testing. Because each scanned beam dose measurement requires the delivery of the entire field, multiple measurements can be time consuming. These quality assurance challenges limit the number of patients who can be treated with this modality. The overall objective of this project is to increase the safety and availability of complex proton therapy treatments by developing a fast volumetric scintillation …

Development Of A New Independent Monte Carlo Dose Calculation Quality Assurance Audit Tool For Clinical Trials, Austin M. Faught

Dissertations & Theses (Open Access)

Introduction: Commercially available treatment planning systems (TPS) may use a number of different radiation dose calculation algorithms during the planning process. The Radiological Physics Center (RPC), tasked with ensuring clinically comparable and consistent dose delivery amongst institutions participating in NCI funded multi-institutional clinical trials, has traditionally relied upon measurements to achieve this objective. As a supplement to the tools used by the RPC, an independent dose calculation tool is needed to determine patient dose distributions in three dimensions so as to act as a quality assurance tool for the dose calculations.

Methods: Multiple source models representing the output of Elekta …

Atomistic Simulations Of The Fusion-Plasma Material Interface, Mostafa Jon Dadras

Jonny Dadras

A key issue for the successful performance of current and future fusion reactors is understanding chemical and physical processes at the Plasma Material Interface (PMI). The material surfaces may be bombarded by plasma particles in a range of impact energies (1 eV - a few keV) and kept at a range of temperatures (300 - 1000 K). The dominant processes at the PMI are reflection and retention of impacting particles and sputtering (chemical and physical). Sputtering leads to surface erosion and pollution of the plasma, both of which degrade reactor performance. Retention influences the recycling of the plasma, and in …

Testing The Well-Posedness Of Characteristic Evolution Of Scalar Waves, Maria Babiuc-Hamilton, Heinz Otto Kreiss, Jeffrey Winicour

Maria C. Babiuc-Hamilton

Recent results have revealed a critical way in which lower order terms affect the well-posedness of the characteristic initial value problem for the scalar wave equation. The proper choice of such terms can make the Cauchy problem for scalar waves well posed even on a background spacetime with closed lightlike curves. These results provide new guidance for developing stable characteristic evolution algorithms. In this regard, we present here the finite difference version of these recent results and implement them in a stable evolution code. We describe test results which validate the code and exhibit some of the interesting features due …

Investigating The Proposed Affordances And Limitations Of The Substance Metaphor For Energy, Lisa Goodhew

Honors Projects

This study explores the instructional advantages and disadvantages of representing energy as a material substance; this is done in the context of a computer simulation that illustrates processes of energy transfer and transformation. These affordances and limitations have been proposed in science education literature as extensions of the substance metaphor itself, but there is little empirical evidence to support them. This study is intended to provide preliminary empirical evidence for these affordances and limitations. We examine data from eight interviews conducted with students from Seattle Pacific University’s introductory physics classes as they used the simulation. We explore the hypotheses that …

Looking For Cosmic Neutrino Background, Chiaki Yanagisawa

Publications and Research

Since the discovery of neutrino oscillation in atmospheric neutrinos by the Super-Kamiokande experiment in 1998, study of neutrinos has been one of exciting fields in high-energy physics. All the mixing angles were measured. Quests for (1) measurements of the remaining parameters, the lightest neutrino mass, the CP violating phase(s), and the sign of mass splitting between the mass eigenstates m₃ and m₁, and (2) better measurements to determine whether the mixing angle θ₂₃ is less than π/4, are in progress in a well-controlled manner. Determining the nature of neutrinos, whether they are Dirac or Majorana particles …

A Solution-Based Temperature Sensor Using The Organic Compound Cutspc, Shahino Mah Abdullah

Shahino Mah Abdullah

An electrochemical cell using an organic compound, copper (II) phthalocyanine-tetrasulfonic acid tetrasodium salt (CuTsPc,) has been fabricated and investigated as a solution-based temperature sensor. The capacitance and resistance of the ITO/CuTsPc solution/ITO chemical cell has been characterized as a function of temperature in the temperature range of 25–80 °C. A linear response with minimal hysteresis is observed. The fabricated temperature sensor has shown high consistency and sensitive response towards a specific range of temperature values.

Dynamics And Manipulation Of Nanomagnets, Liufei Cai

Dissertations, Theses, and Capstone Projects

This thesis presents my work on the spin dynamics of nanomagnets and investigates the possibility of manipulating nanomagnets by various means. Most of the work has been published\cite{LC-PRB2010, LC-PRB2012, LC-PRB2013, LC-EPL2014}. Some has been submitted for publication\cite{LC-arxiv2014}. The structure of this thesis is as follows.

In Chapter 1, I present the theory of manipulation of a nanomagnet by rotating ac fields whose frequency is time dependent. Theory has been developed that maps the problem onto Landau-Zener problem. For the linear frequency sweep the switching phase diagrams are obtained on the amplitude of the ac field and the frequency sweep rate. …

Yang-Mills Theories As Deformations Of Massive Integrable Models, Axel Cortes Cubero

Dissertations, Theses, and Capstone Projects

Yang Mills theory in 2+1 dimensions can be expressed as an array of coupled (1+1)-dimensional principal chiral sigma models. The SU(N) principal chiral sigma model in 1+1 dimensions is integrable, asymptotically free and has massive excitations. We calculate all the form factors and two- point correlation functions of the Noether current and energy-momentum tensor, in

't Hooft's large-N limit (some form factors can be found even at finite N). We use these new form factors to calculate physical quantities in (2+1)-dimensional Yang-Mills theory, generalizing previous SU(2) by P. Orland to SU(N). The anisotropic gauge theory is related to standard isotropic …

String Fluid Cosmological Model With Magnetic Field In Bimetric Theory Of Gravitation, M. S. Borkar, N. P. Gaikwad

Applications and Applied Mathematics: An International Journal (AAM)

In this paper, LRS Bianchi type I string fluid cosmological model with magnetic field in bimetric theory of gravitation is investigated by assuming barotropic equation of state for pressure and density and assuming the bulk viscosity to be inversely proportional to the scalar expansion. The source of energy momentum tensor is a bulk viscous fluid containing one dimensional string with electromagnetic field. The physical and geometrical properties of the model are discussed. The bulk viscosity affected the whole properties of the model.