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Articles 31 - 60 of 31389

Full-Text Articles in Physics

Electromagnetic Interference Reduction Of High-Speed Digital And Analog Circuits Using Engineered Electromagnetic Bandgap Structures, Brandon Ramos Aug 2020

Electromagnetic Interference Reduction Of High-Speed Digital And Analog Circuits Using Engineered Electromagnetic Bandgap Structures, Brandon Ramos

Undergraduate Research Journal

In this paper, we will discuss the concerns of a microstrip two patch antenna system. Coupling of the two-port system can be miniaturized using Electromagnetic Bandgap Structures (EBG) or Defected Ground Structures (DGS) centered between the two patch antennas half a wavelength in size. Different miniaturization methods were used in the design of the antenna system to change the properties of the signal. Changing via locations that are not found on EBG strips themselves, rather found on interleaved ledges between EBG strips allowed for further change in shifting the signals frequency.


Designing A Reactor Chamber For Hot Electron Chemistry On Bimetallic Plasmonic Nanoparticles, Bryn Merrill, Bingjie Zhang, Jerry Larue Aug 2020

Designing A Reactor Chamber For Hot Electron Chemistry On Bimetallic Plasmonic Nanoparticles, Bryn Merrill, Bingjie Zhang, Jerry Larue

SURF Posters and Papers

Catalysis provides pathways for efficient and selective chemical reactions by lowering the energy barriers for desired products. Gold nanoparticles (AuNPs) show excellent promise as plasmonic catalysts. Plasmonic materials have localized surface plasmon resonances, oscillations of the electron bath at the surface of a nanoparticle, that generate energetically intense electric fields which rapidly decay into energetically excited electrons. The excited electrons have the potential to destabilize atoms strongly bound to the catalysts through occupation of antibonding orbitals. Tuning the antibonding orbitals to make them accessible for occupancy by electrons is achieved by coating the AuNP in a thin layer of another ...


Free Charge Carrier Properties In Two-Dimensional Materials And Monoclinic Oxides Studied By Optical Hall Effect, Sean Knight Aug 2020

Free Charge Carrier Properties In Two-Dimensional Materials And Monoclinic Oxides Studied By Optical Hall Effect, Sean Knight

Theses, Dissertations, and Student Research from Electrical & Computer Engineering

In this dissertation, optical Hall effect (OHE) measurements are used to determine the free charge carrier properties of important two-dimensional materials and monoclinic oxides. Two-dimensional material systems have proven useful in high-frequency electronic devices due to their unique properties, such as high mobility, which arise from their two-dimensional nature. Monoclinic oxides exhibit many desirable characteristics, for example low-crystal symmetry which could lead to anisotropic carrier properties. Here, single-crystal monoclinic gallium oxide, an AlInN/GaN-based high-electron-mobility transistor (HEMT) structure, and epitaxial graphene are studied as examples. To characterize these material systems, the OHE measurement technique is employed. The OHE is a ...


A New Look At The Quantum Liouville Theorem, P. T. Leung, G. I. Ni Aug 2020

A New Look At The Quantum Liouville Theorem, P. T. Leung, G. I. Ni

Physics Faculty Publications and Presentations

We clarify certain confusions in the literature of the density operator in quantum mechanics, and demonstrate that the quantum Liouville theorem has the same form in both the Schrodinger and the Heisenberg pictures. Our starting point is to treat the density operator as an observable which has its specific time dependence in each of the two pictures. It is further shown that such a formulation will provide the exact correspondence between classical and quantum statistical mechanics with the Liouville theorem being interpreted as a conservation law, which is derivable from the equation of motion only in the quantum case.


Cooking Systems Using Aluminum Foam, Ryan Tetsuo Mizukami Aug 2020

Cooking Systems Using Aluminum Foam, Ryan Tetsuo Mizukami

Physics

In developing countries, the use of wood burning fires for cooking is cause for illness and death. With this in mind, research was conducted to develop a solar cooking device capable of cooking of soup within 15 mins in order to reduce the negative impacts of cooking with wood. Current methods of solar-based cooking, such as solar concentrators and solar tube ovens, are impractical. A small solar panel is a cost-effective way to produce energy but will not produce enough power to cook within a reasonable amount of time. Even if it is assumed that all of the energy produced ...


Adaptive Spline Fitting With Particle Swarm Optimization, Soumya Mohanty, Ethan Fahnestock Aug 2020

Adaptive Spline Fitting With Particle Swarm Optimization, Soumya Mohanty, Ethan Fahnestock

Physics and Astronomy Faculty Publications and Presentations

In fitting data with a spline, finding the optimal placement of knots can significantly improve the quality of the fit. However, the challenging high-dimensional and non-convex optimization problem associated with completely free knot placement has been a major roadblock in using this approach. We present a method that uses particle swarm optimization (PSO) combined with model selection to address this challenge. The problem of overfitting due to knot clustering that accompanies free knot placement is mitigated in this method by explicit regularization, resulting in a significantly improved performance on highly noisy data. The principal design choices available in the method ...


Diffuse Spectra Model Of Photoluminescence In Carbon Quantum Dots, S. E. Kumekov, N. K. Saitova, Karen S. Martirosyan Aug 2020

Diffuse Spectra Model Of Photoluminescence In Carbon Quantum Dots, S. E. Kumekov, N. K. Saitova, Karen S. Martirosyan

Physics and Astronomy Faculty Publications and Presentations

The attractive aspect of excitation related to fluorescence nature in carbon quantum dots (CQD) has guided to several assumptions correlated with clusters size distribution, shapes as well as presence of different emissive states. In this study, a dimer–excimer model of photoluminescence (PL) in CQD describing discrete multiple electronic states for the excitation-dependent emission is described. The functional dependence of the characteristic width of the diffuse spectra of PL on the size of a quantum dots are calculated. The effective width of PL spectrum can be tuned from 0.1 to 1 eV.


Simulation And Development Of The Radial Time Projection Chamber For The Bonus12 Experiment In Clas12, Nathan M. Dzbenski Aug 2020

Simulation And Development Of The Radial Time Projection Chamber For The Bonus12 Experiment In Clas12, Nathan M. Dzbenski

Physics Theses & Dissertations

Knowledge of the structure of nucleons (i:e: protons and neutrons) is a central topic of interest to nuclear/particle physicists. Much more is known about the structure of the proton than the neutron due to the lack of high-density free neutron targets. The Barely Off-shell Nucleon Structure experiment (BONuS12) at Jefferson Lab (JLab) is a second generation experiment upgraded/optimized to advance our knowledge of the neutron's structure using the deep-inelastic scattering of electrons off deuterium. Typically, since deuterium is a nuclear target, corrections for off-shell and nuclear binding effects must be taken into account in order to ...


Storm-Time Equatorial Thermospheric Dynamics And Electrodynamics, Luis A. Navarro Dominguez Aug 2020

Storm-Time Equatorial Thermospheric Dynamics And Electrodynamics, Luis A. Navarro Dominguez

All Graduate Theses and Dissertations

We present the first complete study of the dynamics of the equatorial upper atmosphere (180-350 km) during periods of strong magnetic activity driven by the Sun, which are generally referred as geomagnetic storms. These storms have the potential to considerably affect satellite-based communications and navigation systems among other severe technological challenges. We used large databases of two of the most important parameters at these altitudes, which are the velocities of the neutral and ionized gas (plasma) referred to as neutral winds and plasma drifts. These measurements were acquired in the Peruvian equatorial region by the Jicamarca radar and by a ...


Massive Graviton Spectra In Supergravity, Kevin Dimmitt Aug 2020

Massive Graviton Spectra In Supergravity, Kevin Dimmitt

All Graduate Theses and Dissertations

Development of a unified theory of physics would pave the way for new research and technology development for many years to come. Unfortunately, the two best current theories explaining nature, the Standard Model of particle physics and general relativity, do not seem to be compatible, requiring the development of more complicated models which contains both of these at their respective limits. Supergravities are one set of theories which may, at least in part, provide hints as to how it may be possible to unify physics into a single model.

This research project follows from a line of investigation which the ...


Active Magnetic Radiation Shielding For Long-Duration Human Spaceflight, Kristine Ferrone Aug 2020

Active Magnetic Radiation Shielding For Long-Duration Human Spaceflight, Kristine Ferrone

The University of Texas MD Anderson Cancer Center UTHealth Graduate School of Biomedical Sciences Dissertations and Theses (Open Access)

Exploration of interplanetary space presents dramatic hazards to human survival.

Space radiation hazards outside the protection of the Earth’s magnetosphere can

produce both acute and chronic health risks and thus become limiting factors for

NASA’s planned mission to Mars by the 2030s. Radiation exposure on a Mars mission

is delivered primarily by high energy ions from galactic cosmic rays and moderate

energy protons from solar particle events. The chronic radiation dose due to galactic

cosmic rays on a typical Mars mission is on the order of 1 Sv, and additional acute

radiation dose from solar flares can reach ...


Developing Arduino Coding Curriculum, Tyler Brown, Riley Bucheitte, Timothy Kidd Jul 2020

Developing Arduino Coding Curriculum, Tyler Brown, Riley Bucheitte, Timothy Kidd

Summer Undergraduate Research Program (SURP)

No abstract provided.


Analyzing And Classifying Single Molecule Microscopy Data, Troy Buzynski, Ali Tabei Jul 2020

Analyzing And Classifying Single Molecule Microscopy Data, Troy Buzynski, Ali Tabei

Summer Undergraduate Research Program (SURP)

No abstract provided.


Modeling The Griffiths Phase In Manganese Intercalated Tantalum Disulfide [Poster], Aaron Janaszak, Lukas Stuelke, Paul Shand Jul 2020

Modeling The Griffiths Phase In Manganese Intercalated Tantalum Disulfide [Poster], Aaron Janaszak, Lukas Stuelke, Paul Shand

Summer Undergraduate Research Program (SURP)

No abstract provided.


Design, Monitoring And Management Approaches For The Root-Zone In Microgravity, Scott B. Jones Jul 2020

Design, Monitoring And Management Approaches For The Root-Zone In Microgravity, Scott B. Jones

Funded Research Records

No abstract provided.


High-Temperature Optical Properties Of Indium Tin Oxide Thin-Films, Jiwoong Kim, Sujan Shrestha, Maryam Souri, John G. Connell, Sungkyun Park, Ambrose Seo Jul 2020

High-Temperature Optical Properties Of Indium Tin Oxide Thin-Films, Jiwoong Kim, Sujan Shrestha, Maryam Souri, John G. Connell, Sungkyun Park, Ambrose Seo

Physics and Astronomy Faculty Publications

Indium tin oxide (ITO) is one of the most widely used transparent conductors in optoelectronic device applications. We investigated the optical properties of ITO thin films at high temperatures up to 800 °C using spectroscopic ellipsometry. As temperature increases, amorphous ITO thin films undergo a phase transition at ~ 200 °C and develop polycrystalline phases with increased optical gap energies. The optical gap energies of both polycrystalline and epitaxial ITO thin films decrease with increasing temperature due to electron-phonon interactions. Depending on the background oxygen partial pressure, however, we observed that the optical gap energies exhibit reversible changes, implying that the ...


The Crisis Of Communication In The Information Age: Revisiting C.P. Snow's Two Cultures In The Era Of Fake News, Aaron Green Jul 2020

The Crisis Of Communication In The Information Age: Revisiting C.P. Snow's Two Cultures In The Era Of Fake News, Aaron Green

Irish Communication Review

The purpose of this paper is to revisit C.P. Snow’s “Two Cultures” lecture in light of the cultural dominance of information technology. The crisis of communication in the information age, whether in fake news, political polarisation or science denial, has come about because both scientific and literary cultures, in seeking a world without entropy, have inadvertently stumbled upon a world without meaning. In order to explain how this has happened, the paper first explores Snow's challenge: to describe the second law of thermodynamics. The paper then provides a description of entropy that is neutral with regard to ...


Swir Photodetection And Visualization Realized By Incorporating An Organic Swir Sensitive Bulk Heterojunction, Ning Li, Zhaojue Lan, Ying Suet Lau, Jiajuan Xue, Dahui Zhao, Furong Zhao Jul 2020

Swir Photodetection And Visualization Realized By Incorporating An Organic Swir Sensitive Bulk Heterojunction, Ning Li, Zhaojue Lan, Ying Suet Lau, Jiajuan Xue, Dahui Zhao, Furong Zhao

HKBU Staff Publication

Short‐wavelength infrared (SWIR) photodetection and visualization has profound impacts on different applications. In this work, a large‐area organic SWIR photodetector (PD) that is sensitive to SWIR light over a wavelength range from 1000 to 1600 nm and a SWIR visualization device that is capable of upconverting SWIR to visible light are developed. The organic SWIR PD, comprising an organic SWIR sensitive blend of a near‐infrared polymer and a nonfullerene n‐type small molecule SWIR dye, demonstrates an excellent capability for real‐time heart rate monitoring, offering an attractive opportunity for portable and wearable healthcare gadgets. The SWIR ...


A Lab Skills Diagnostic Test, John Zwart Jul 2020

A Lab Skills Diagnostic Test, John Zwart

Faculty Work Comprehensive List

The American Association of Physics Teachers recommends that physics majors have proficiency in the following lab skills: constructing knowledge, modeling, designing experiments, analyzing and visualizing data, and communicating physics. I have developed a brief multiple-choice questionnaire to assess incoming students’ lab skill level in these areas. It was administered as both a pre-test and post-test for the first semester of introductory calculus-based physics. Preliminary results indicate that little improvement on the skills tested occurs without explicit instruction.


Covid-19: In The Absence Of Vaccination – ‘Mask-The-Nation’, Roy D. Sleator, Steven Darby, Alan Giltinan, Niall Smith Jul 2020

Covid-19: In The Absence Of Vaccination – ‘Mask-The-Nation’, Roy D. Sleator, Steven Darby, Alan Giltinan, Niall Smith

Department of Biological Sciences Publications

“In the absence of a vaccine, or effective antiviral, one of our only remaining strategies for controlling COVID-19 is to physically block the spread of SARS-CoV-2 in the community”


Flip And Neimark–Sacker Bifurcations In A Coupled Logistic Map System, A. Mareno, Lars Q. English Jul 2020

Flip And Neimark–Sacker Bifurcations In A Coupled Logistic Map System, A. Mareno, Lars Q. English

Faculty and Staff Publications By Year

In this paper, we consider a system of strongly coupled logistic maps involving two parameters. We classify and investigate the stability of its fixed points. A local bifurcation analysis of the system using center manifold theory is undertaken and then supported by numerical computations. This reveals the existence of a flip and Neimark–Sacker bifurcations.


Spacetime Groups, Ian M. Anderson, Charles G. Torre Jul 2020

Spacetime Groups, Ian M. Anderson, Charles G. Torre

All Physics Faculty Publications

A spacetime group is a connected 4-dimensional Lie group G endowed with a left invariant Lorentz metric h and such that the connected component of the isometry group of h is G itself. The Newman-Penrose formalism is used to give an algebraic classification of spacetime groups, that is, we determine a complete list of inequivalent spacetime Lie algebras, which are pairs, (g, n), with g being a 4-dimensional Lie algebra and n being a Lorentzian inner product on g. A full analysis of the equivalence problem for spacetime Lie algebras is given which leads to a completely algorithmic solution to ...


Eusectra: European Nuclear Security Training Centre Providing Hands-On Training And Education In Nuclear Security And Safeguards, Willem Janssens, Veronique Berthou, Abbas Kamel, Jean Galy, Klaus Luetzenkirchen, Klaus Mayer, Stefan Nonneman Jul 2020

Eusectra: European Nuclear Security Training Centre Providing Hands-On Training And Education In Nuclear Security And Safeguards, Willem Janssens, Veronique Berthou, Abbas Kamel, Jean Galy, Klaus Luetzenkirchen, Klaus Mayer, Stefan Nonneman

International Journal of Nuclear Security

The European Nuclear Security Training Centre (EUSECTRA) inaugurated under this global name about 10 years ago and operated by the European Commission Joint Research Centre (JRC), located both on the Karlsruhe (Germany) and Ispra (Italy) sites, includes a large variety of capacity building and professional development activities which span from the hands-on training for nuclear security and safeguards actors (e.g. respectively border guards or customs and nuclear inspectors) to educational efforts in both nuclear security and safeguards. Whereas the first ones, which gave rise to the new name, focus mainly on detection, on-site assistance, crime-scene management, technical reach-back and ...


Development And Demonstration Of A Pico-Watt Calorimeter For Optical Absorption Spectroscopy, Behshad Roshanzadeh Jul 2020

Development And Demonstration Of A Pico-Watt Calorimeter For Optical Absorption Spectroscopy, Behshad Roshanzadeh

Optical Science and Engineering ETDs

An optical calorimeter for sensitive absorption measurements of non-radiative samples at 4 K was designed, built, and demonstrated. It consists of a cryostat cooled by a commercial pulse tube (PTC) refrigerator, a measurement chamber housing the sample and thermometers, and various fiber-coupled light sources. By employing measures to damp mechanical noise from the environment and active temperature stabilization of critical components of the instrument temperature noise as low as 6 nK/√Hz at 50 mHz was achieved under 15 mW of optical excitation. An optical absorption induced temperature increase of the sample as small as 2.5 nK could be ...


Generation Of Correlated Dual Frequency Combs With Pm Fiber Lasers For High-Precision Metrology, Hanieh Afkhamiardakani Jul 2020

Generation Of Correlated Dual Frequency Combs With Pm Fiber Lasers For High-Precision Metrology, Hanieh Afkhamiardakani

Optical Science and Engineering ETDs

Intracavity Phase Interferometry (IPI) using two correlated, counter-propagating frequency combs (pulse trains) in mode-locked lasers has evolved into a powerful technique for high-precision metrology. In this method a physical parameter to be measured imparts a phase shift onto a pulse circulating in the laser cavity. Inside a laser cavity, that phase shift becomes a frequency shift (phase shift/round-trip time) applied to the whole frequency comb created by this pulse as it exits the cavity at each round-trip. This frequency shift is measured by interfering this comb with a reference comb created by a reference pulse circulating in the same ...


Physical Protection System, Corrective Actions, And Weaknesses Identification Based On Nuclear Security Series: The Hypothetical Atomic Research Institute (Hari) Case, Ouadie Kabach, Abdelouahed Chetaine, Abdelfettah Benchrif Jul 2020

Physical Protection System, Corrective Actions, And Weaknesses Identification Based On Nuclear Security Series: The Hypothetical Atomic Research Institute (Hari) Case, Ouadie Kabach, Abdelouahed Chetaine, Abdelfettah Benchrif

International Journal of Nuclear Security

The paper is an attempt, based on the IAEA’s Nuclear Security Series (NSS), to identify any unacceptable dysfunction of Physical Protection System (PPS) of the Material Test Reactor (MTR) facility in a Hypothetical Atomic Research Institute (HARI). The evaluation of an existing or a proposed PPS requires a methodical approach whereby the ability of the security system to meet defined protection goals as the safeguard against possibility of sabotage and theft should be measured. Without such kind of careful assessment, the PPS might waste valuable resources on unnecessary protection or, worse yet, fail to provide adequate protection at critical ...


Quantum Criticality In Strongly Correlated Electron Systems, Samuel Obadiah Kellar Jul 2020

Quantum Criticality In Strongly Correlated Electron Systems, Samuel Obadiah Kellar

LSU Doctoral Dissertations

The study of the Hubbard model in three dimensions contains a variety of phases dependent upon the chosen parameters. This thesis shows that there is the indication of a zero temperature phase transition at a finite doping. The Hubbard model has been used to identify a similar quantum critical point in two dimensions. The presented results continue these investigations. The system demonstrates a strange metal phase at finite temperature which cannot be described in term of the conventional Fermi liquid. While there have been extensive studies over the past three decades for such materials in two dimensions, there are few ...


Identifying Structure Transitions Using Machine Learning Methods, Nicholas Walker Jul 2020

Identifying Structure Transitions Using Machine Learning Methods, Nicholas Walker

LSU Doctoral Dissertations

Methodologies from data science and machine learning, both new and old, provide an exciting opportunity to investigate physical systems using extremely expressive statistical modeling techniques. Physical transitions are of particular interest, as they are accompanied by pattern changes in the configurations of the systems. Detecting and characterizing pattern changes in data happens to be a particular strength of statistical modeling in data science, especially with the highly expressive and flexible neural network models that have become increasingly computationally accessible in recent years through performance improvements in both hardware and algorithmic implementations. Conceptually, the machine learning approach can be regarded as ...


Wave-Optics Investigation Of Turbulence Thermal Blooming Interaction: Ii. Using Time-Dependent Simulations, Mark F. Spencer Jul 2020

Wave-Optics Investigation Of Turbulence Thermal Blooming Interaction: Ii. Using Time-Dependent Simulations, Mark F. Spencer

Faculty Publications

Part II of this two-part paper uses wave-optics simulations to look at the Monte Carlo averages associated with turbulence and time-dependent thermal blooming (TDTB). The goal is to investigate turbulence thermal blooming interaction (TTBI). At wavelengths near 1 μm, TTBI increases the amount of constructive and destructive interference (i.e., scintillation) that results from high-power laser beam propagation through distributed-volume atmospheric aberrations. As a result, we use the spherical-wave Rytov number, the number of wind-clearing periods, and the distortion number to gauge the strength of the simulated turbulence and TDTB. These parameters simply greatly given propagation paths with constant atmospheric ...


Wave-Optics Investigation Of Turbulence Thermal Blooming Interaction: I. Using Steady-State Simulations, Mark F. Spencer Jul 2020

Wave-Optics Investigation Of Turbulence Thermal Blooming Interaction: I. Using Steady-State Simulations, Mark F. Spencer

Faculty Publications

Part I of this two-part paper uses wave-optics simulations to look at the Monte Carlo averages associated with turbulence and steady-state thermal blooming (SSTB). The goal is to investigate turbulence thermal blooming interaction (TTBI). At wavelengths near 1 μm, TTBI increases the amount of constructive and destructive interference (i.e., scintillation) that results from high-power laser beam propagation through distributed-volume atmospheric aberrations. As a result, we use the spherical-wave Rytov number and the distortion number to gauge the strength of the simulated turbulence and SSTB. These parameters simplify greatly given propagation paths with constant atmospheric conditions. In addition, we use ...