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2015

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Full-Text Articles in Physical Sciences and Mathematics

Models Describing The Sea Level Rise In Key West, Florida, Karm-Ervin Jean Nov 2015

Models Describing The Sea Level Rise In Key West, Florida, Karm-Ervin Jean

FIU Electronic Theses and Dissertations

Lately, we have been noticing an unusual rise in the sea level near many Floridian cities. By 2060, scientists believe that the sea level in the city of Key West will reach between 22.86 to 60.96 centimeters (Strauss et al. 2012). The consequences of sea level rise are unpleasant by gradually tearing away our beaches and natural resources, destroying our homes and businesses, etc. Definitively, a continual increase of the sea level will affect everyone either directly or indirectly.

In this study, the sea level measurements of four Floridian coastal cities (including Key West) are collected in order to describe …


Gis-Integrated Mathematical Modeling Of Social Phenomena At Macro- And Micro- Levels—A Multivariate Geographically-Weighted Regression Model For Identifying Locations Vulnerable To Hosting Terrorist Safe-Houses: France As Case Study, Elyktra Eisman Nov 2015

Gis-Integrated Mathematical Modeling Of Social Phenomena At Macro- And Micro- Levels—A Multivariate Geographically-Weighted Regression Model For Identifying Locations Vulnerable To Hosting Terrorist Safe-Houses: France As Case Study, Elyktra Eisman

FIU Electronic Theses and Dissertations

Adaptability and invisibility are hallmarks of modern terrorism, and keeping pace with its dynamic nature presents a serious challenge for societies throughout the world. Innovations in computer science have incorporated applied mathematics to develop a wide array of predictive models to support the variety of approaches to counterterrorism. Predictive models are usually designed to forecast the location of attacks. Although this may protect individual structures or locations, it does not reduce the threat—it merely changes the target. While predictive models dedicated to events or social relationships receive much attention where the mathematical and social science communities intersect, models dedicated to …


Development Of A Two-Fluid Drag Law For Clustered Particles Using Direct Numerical Simulation And Validation Through Experiments, Ahmadreza Abbasi Baharanchi Nov 2015

Development Of A Two-Fluid Drag Law For Clustered Particles Using Direct Numerical Simulation And Validation Through Experiments, Ahmadreza Abbasi Baharanchi

FIU Electronic Theses and Dissertations

This dissertation focused on development and utilization of numerical and experimental approaches to improve the CFD modeling of fluidization flow of cohesive micron size particles. The specific objectives of this research were: (1) Developing a cluster prediction mechanism applicable to Two-Fluid Modeling (TFM) of gas-solid systems (2) Developing more accurate drag models for Two-Fluid Modeling (TFM) of gas-solid fluidization flow with the presence of cohesive interparticle forces (3) using the developed model to explore the improvement of accuracy of TFM in simulation of fluidization flow of cohesive powders (4) Understanding the causes and influential factor which led to improvements and …


Online Moving Object Visualization With Geo-Referenced Data, Guangqiang Zhao Nov 2015

Online Moving Object Visualization With Geo-Referenced Data, Guangqiang Zhao

FIU Electronic Theses and Dissertations

As a result of the rapid evolution of smart mobile devices and the wide application of satellite-based positioning devices, the moving object database (MOD) has become a hot research topic in recent years. The moving objects generate a large amount of geo-referenced data in different types, such as videos, audios, images and sensor logs. In order to better analyze and utilize the data, it is useful and necessary to visualize the data on a map.

With the rise of web mapping, visualizing the moving object and geo-referenced data has never been so easy. While displaying the trajectory of a moving …


Science Undergraduate Research Conference 2015 Booklet, Dublin Institute Of Technology, Institute Of Technology, Tallaght, Institute Of Technology, Blanchardstown Nov 2015

Science Undergraduate Research Conference 2015 Booklet, Dublin Institute Of Technology, Institute Of Technology, Tallaght, Institute Of Technology, Blanchardstown

Group Reports

Dublin Institute of Technology (DIT), IT Tallaght and IT Blanchardstown hosted the Science Undergraduate Research Conference (SURC 2015) on 13th November 2015 in DIT's Grangegorman Campus. 25 students from DIT, IT Tallaght and IT Blanchardstown who completed an undergraduate research project in a Scientific discipline in the academic year 2014-15 presented at this conference.

The aims of the conference were to:

  1. Provide current students with an opportunity to gain an understanding of the work which has been undertaken by recent graduates, and the career opportunities that exist for graduates in Scientific disciplines.
  2. Provide recent graduates with an opportunity to gain …


High Pressure Studies Of Nanostructured Tio2 And Li4ti5o12 Using Raman Spectroscopy And Synchrotron X-Ray Radiation, Fengping Xiao Nov 2015

High Pressure Studies Of Nanostructured Tio2 And Li4ti5o12 Using Raman Spectroscopy And Synchrotron X-Ray Radiation, Fengping Xiao

Electronic Thesis and Dissertation Repository

Nanomaterials have been extensively studied due to their distinctive properties such as surface effect, small-size effect and quantum size effect. In recent year, investigations of the structural and phase transformations of nanomaterials under high pressure are receiving increasing attentions. In addition to composition and synthetic routes, pressure provides a clean way to adjust interatomic distance and hence affect the crystal structure and thus properties of the nanostructured materials.Two nanomaterials (i.e. TiO2 and Li4Ti5O12) with different morphologies are studied in this thesis.

In part I, the high-pressure behaviours of four hydrothermal synthesized 1D rutile …


Characterization Of Physical, Spectroscopic And Thermal Properties Of Biofield Treated Biphenyl, Mahendra Kumar Trivedi, Rama Mohan Tallapragada, Alice Branton, Dahryn Trivedi, Gopal Nayak, Rakesh K. Mishra, Snehasis Jana Nov 2015

Characterization Of Physical, Spectroscopic And Thermal Properties Of Biofield Treated Biphenyl, Mahendra Kumar Trivedi, Rama Mohan Tallapragada, Alice Branton, Dahryn Trivedi, Gopal Nayak, Rakesh K. Mishra, Snehasis Jana

Mahendra Kumar Trivedi

Biphenyl is used as an intermediate for synthesis of various pharmaceutical compounds. The objective of present research was to investigate the influence of biofield treatment on physical, spectroscopic and thermal properties of biphenyl. The study was performed in two groups (control and treated). The control group remained as untreated, and biofield treatment was given to treated group. The control and treated biphenyl were characterized by X-ray diffraction (XRD), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), Fourier transform infrared (FT-IR) spectroscopy, Ultraviolet-visible (UV-Vis) spectroscopy and surface area analysis. The treated biphenyl showed decrease in intensity of XRD peaks as compared to …


Characterization Of Physical, Thermal And Spectral Properties Of Biofield Treated 2,6-Dichlorophenol, Mahendra Kumar Trivedi, Rama Mohan Tallapragada, Alice Branton, Dahryn Trivedi, Gopal Nayak, Rakesh K. Mishra, Snehasis Jana Nov 2015

Characterization Of Physical, Thermal And Spectral Properties Of Biofield Treated 2,6-Dichlorophenol, Mahendra Kumar Trivedi, Rama Mohan Tallapragada, Alice Branton, Dahryn Trivedi, Gopal Nayak, Rakesh K. Mishra, Snehasis Jana

Mahendra Kumar Trivedi

2,6-Dichlorophenol (2,6-DCP) is a compound used for the synthesis of chemicals and pharmaceutical agents. The present work is intended to evaluate the impact of Mr. Trivedi’s biofield energy treatment on physical, thermal and spectral properties of the 2,6-DCP. The control and treated 2,6-DCP were characterized by various analytical techniques such as X-ray diffraction (XRD), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), Fourier transform infrared (FT-IR) spectroscopy, and ultra violet-visible spectroscopy (UV-vis) analysis. The XRD results showed the increase in crystallite size of treated sample by 28.94% as compared to the control sample. However, the intensity of the XRD peaks of …


Match-Making For Stability: A Survey Of The Stable Marriage Problem, Adam J. Hammett Nov 2015

Match-Making For Stability: A Survey Of The Stable Marriage Problem, Adam J. Hammett

Mathematics Colloquium

No abstract provided.


Cosmic Radiation, Anthony Keane Nov 2015

Cosmic Radiation, Anthony Keane

The ITB Journal

The planet Earth orbits the Sun in what is often considered to be empty space but is in fact full of very small charged particles speeding in all directions. The situation can be compared to the Earth having to constantly travel in a light shower of rain and with the atmosphere acting like an umbrella. The 'rain' is made up of charged particles called 'Cosmic Rays'. The name cosmic ray was given long ago to invisible ionising radiation that could mysteriously discharge an electroscope even when the electroscope was heavy insulated. Early scientists quickly established a relationship between the rate …


Fusion Algebras & Accidental Trigonometry, Christopher D. Goff Nov 2015

Fusion Algebras & Accidental Trigonometry, Christopher D. Goff

College of the Pacific Faculty Presentations

Have you ever been working in one area of math, and another area arises unexpectedly? While working on a problem in 2008, we inadvertently discovered some trigonometric identities. This talk will explain fusion algebras, which are relatively simple algebraic objects that demonstrate nice algebraic applications of linear algebra. Then we will see how trigonometry can arise in even this most algebraic of settings.


The Firece Green Fire: Vol. 6 Issue 10, Wofford College Environmental Studies Program Nov 2015

The Firece Green Fire: Vol. 6 Issue 10, Wofford College Environmental Studies Program

The Fierce Green Fire

No abstract provided.


Energy Dependence Of Acceptance-Corrected Dielectron Excess Mass Spectrum At Mid-Rapidity In Au + Au Collisions At √SNn = 19.6 And 200 Gev, James K. Adkins, Renee H. Fatemi, Suvarna Ramachandran, L. Adamczyk, G. Agakishiev, M. M. Aggarwal, Z. Ahammed, I. Alekseev, J. Alford, A. Aparin, D. Arkhipkin, E. C. Aschenauer, G. S. Averichev Nov 2015

Energy Dependence Of Acceptance-Corrected Dielectron Excess Mass Spectrum At Mid-Rapidity In Au + Au Collisions At √SNn = 19.6 And 200 Gev, James K. Adkins, Renee H. Fatemi, Suvarna Ramachandran, L. Adamczyk, G. Agakishiev, M. M. Aggarwal, Z. Ahammed, I. Alekseev, J. Alford, A. Aparin, D. Arkhipkin, E. C. Aschenauer, G. S. Averichev

Physics and Astronomy Faculty Publications

The acceptance-corrected dielectron excess mass spectra, where the known hadronic sources have been subtracted from the inclusive dielectron mass spectra, are reported for the first time at mid-rapidity ∣yee∣+ Au collisions at √sNN = 19.6 and 200 GeV. The excess mass spectra are consistently described by a model calculation with a broadened ρ spectral function for Mee < 1.1 GeV/c2. The integrated dielectron excess yield at √sNN = 19.6 GeV for 0.4 < Mee < 0.75 GeV/c2, normalized to the charged particle multiplicity at mid-rapidity, has a value similar to that in ln+ln collisions at …


Convergence Properties Of The Randomized Extended Gauss-Seidel And Kaczmarz Methods, Anna Ma, Deanna Needell, Aaditya Ramdas Nov 2015

Convergence Properties Of The Randomized Extended Gauss-Seidel And Kaczmarz Methods, Anna Ma, Deanna Needell, Aaditya Ramdas

CMC Faculty Publications and Research

The Kaczmarz and Gauss-Seidel methods both solve a linear system Xβ=y by iteratively refining the solution estimate. Recent interest in these methods has been sparked by a proof of Strohmer and Vershynin which shows the randomized Kaczmarz method converges linearly in expectation to the solution. Lewis and Leventhal then proved a similar result for the randomized Gauss-Seidel algorithm. However, the behavior of both methods depends heavily on whether the system is under or overdetermined, and whether it is consistent or not. Here we provide a unified theory of both methods, their variants for these different settings, and draw connections between …


Six Planets Orbiting Hd 219134, Steve Vogt, Jennifer Burt, Stefano Meschiari, R. Paul Butler, Gregory W. Henry, Songhu Wang, Brad Holden, Cyril Gapp, Russell Hanson, Pamela Arriagada, Sandy Keiser, Johanna Teske, Gregory Laughlin Nov 2015

Six Planets Orbiting Hd 219134, Steve Vogt, Jennifer Burt, Stefano Meschiari, R. Paul Butler, Gregory W. Henry, Songhu Wang, Brad Holden, Cyril Gapp, Russell Hanson, Pamela Arriagada, Sandy Keiser, Johanna Teske, Gregory Laughlin

Information Systems and Engineering Management Research Publications

We present new, high-precision Doppler radial velocity (RV) data sets for the nearby K3V star HD 219134. The data include 175 velocities obtained with the HIRES Spectrograph at the Keck I Telescope and 101 velocities obtained with the Levy Spectrograph at the Automated Planet Finder Telescope at Lick Observatory. Our observations reveal six new planetary candidates, with orbital periods of P = 3.1, 6.8, 22.8, 46.7, 94.2, and 2247 days, spanning masses of ${\mathcal{M}}\mathrm{sin}i=3.8,$ 3.5, 8.9, 21.3, 10.8, and $108\;{{\mathcal{M}}}_{\oplus }$, respectively. Our analysis indicates that the outermost signal is unlikely to be an artifact induced by stellar activity. In …


Narrow Na And K Absorption Lines Toward T Tauri Stars: Tracing The Atomic Envelope Of Molecular Clouds, I. Pascucci, Suzan Edwards, M Heyer, E. Rigliaco, L. Hillenbrand, U. Gorti, D. Hollenbach, M. N. Simon Nov 2015

Narrow Na And K Absorption Lines Toward T Tauri Stars: Tracing The Atomic Envelope Of Molecular Clouds, I. Pascucci, Suzan Edwards, M Heyer, E. Rigliaco, L. Hillenbrand, U. Gorti, D. Hollenbach, M. N. Simon

Astronomy: Faculty Publications

We present a detailed analysis of narrow Na I and K I absorption resonance lines toward nearly 40 T Tauri stars in Taurus with the goal of clarifying their origin. The Na I λ5889.95 line is detected toward all but one source, while the weaker K I λ7698.96 line is detected in about two-thirds of the sample. The similarity in their peak centroids and the significant positive correlation between their equivalent widths demonstrate that these transitions trace the same atomic gas. The absorption lines are present toward both disk and diskless young stellar objects, which excludes cold gas within the …


Bacterial Community Dynamics In Marine Sponge Cinachyrella Kuekenthali Under Irradiance And Antibiotics, Nidhi Vijayan Nov 2015

Bacterial Community Dynamics In Marine Sponge Cinachyrella Kuekenthali Under Irradiance And Antibiotics, Nidhi Vijayan

HCNSO Student Theses and Dissertations

The Marine sponge Cinachyrella sp used in this study are commonly found in offshore South Florida and Caribbean waters and appeared to be resilient in closed system aquaculture. Marine sponges host diverse bacterial symbionts that are distinct compared to bacteria found in ambient seawater, however the roles of a large fraction of the bacterial community in marine sponges are unknown. Comparison of symbiotic to aposymbiotic (bacteria-free) sponges could provide information about interactions (metabolic and physiologic) between the bacteria and sponge. In this study, a single Cinachyrella kuekenthali individual was subsectioned into explants (N=240) in order to provide identical bacterial communities …


Molecular Gas And Star Formation In The Cartwheel, James L. Higdon, Sarah J.U. Higdon, Sergio Martín Ruiz, Richard J. Rand Nov 2015

Molecular Gas And Star Formation In The Cartwheel, James L. Higdon, Sarah J.U. Higdon, Sergio Martín Ruiz, Richard J. Rand

Department of Physics and Astronomy Faculty Publications

Atacama Large Millimeter/submillimeter Array 12CO(J = 1–0) observations are used to study the cold molecular ISM of the Cartwheel ring galaxy and its relation to H i and massive star formation (SF). CO moment maps find (2.69 ± 0.05) × 109 M⊙ of H2 associated with the inner ring (72%) and nucleus (28%) for a Galactic ICO-to- conversion factor (αCO). The spokes and disk are not detected. Analysis of the inner ring's CO kinematics shows it to be expanding (Vexp = 68.9 ± 4.9 km s−1), implying an ≈70 Myr age. Stack averaging …


Progress Toward A Structure-Function Relationship For Novel, Small-Molecule Inhibitors Of Plasminogen Activator Inhibitor-1, Sarah Burke Nov 2015

Progress Toward A Structure-Function Relationship For Novel, Small-Molecule Inhibitors Of Plasminogen Activator Inhibitor-1, Sarah Burke

Master's Theses and Doctoral Dissertations

Plasminogen activator inhibitor-1 (PAI-1) is a serpin protein whose function is to inhibit tissue-type plasminogen activator (tPA) and urokinase-type plasminogen activator (uPA), and hence, fibrinolysis. This inhibition leads to decreased plasminogen to plasmin conversion, which results in deleterious effects on the organism, such as blood clots. Elevated levels of PAI-1 are implicated in a variety of diseases and conditions. We have synthesized a variety of novel, small-molecule PAI-1 inhibitors in order to establish a structure-function relationship throughout the compounds. This goal was accomplished through an iterative process in which only one aspect of the molecule was altered at a time. …


Gaseous Carbon Emissions (Methane And Carbon Dioxide) From Wetland Soils In A Re-Created Everglades Landscape, Bradley R. Schonhoff Nov 2015

Gaseous Carbon Emissions (Methane And Carbon Dioxide) From Wetland Soils In A Re-Created Everglades Landscape, Bradley R. Schonhoff

FIU Electronic Theses and Dissertations

Reducing the rates of greenhouse gas (GHG) emissions is critical in combatting global climate change. Carbon dioxide (CO2) and methane (CH4) are the two most important carbon-based GHGs, for their atmospheric warming potential. Wetlands such as the Florida Everglades play major roles in the global carbon cycle, as varying hydrologic conditions lead to differential production rates of these two GHGs. This study measured CO2 and CH4 emissions in a re-created Everglades ridge-and-slough wetland, where water levels were controlled to reflect natural flood patterns. As expected, lower elevations were flooded longer and produced more CH …


Robust Modeling And Predictions Of Greenhouse Gas Fluxes From Forest And Wetland Ecosystems, Khandker S. Ishtiaq Nov 2015

Robust Modeling And Predictions Of Greenhouse Gas Fluxes From Forest And Wetland Ecosystems, Khandker S. Ishtiaq

FIU Electronic Theses and Dissertations

The land-atmospheric exchanges of carbon dioxide (CO2) and methane (CH4) are major drivers of global warming and climatic changes. The greenhouse gas (GHG) fluxes indicate the dynamics and potential storage of carbon in terrestrial and wetland ecosystems. Appropriate modeling and prediction tools can provide a quantitative understanding and valuable insights into the ecosystem carbon dynamics, while aiding the development of engineering and management strategies to limit emissions of GHGs and enhance carbon sequestration. This dissertation focuses on the development of data-analytics tools and engineering models by employing a range of empirical and semi-mechanistic approaches to robustly …


An Overview Of The Dynamic Interplay Between The Space Environment & Spacecraft Materials, Jr Dennison Nov 2015

An Overview Of The Dynamic Interplay Between The Space Environment & Spacecraft Materials, Jr Dennison

Presentations

No abstract provided.


Novel Enzyme Perspectives: Arylalkylamine N-Acyltransferases From Bombyx Mori & 1-Deoxy- D-Xylulose-5-Phosphate Synthase From Plasmodium Falciparum And Plasmodium Vivax, Matthew R. Battistini Nov 2015

Novel Enzyme Perspectives: Arylalkylamine N-Acyltransferases From Bombyx Mori & 1-Deoxy- D-Xylulose-5-Phosphate Synthase From Plasmodium Falciparum And Plasmodium Vivax, Matthew R. Battistini

USF Tampa Graduate Theses and Dissertations

This dissertation is dedicated to the research and investigation of novel enzymes and the methods used to study them, with physiological roles ranging from isoprenoid biosynthesis to neurotransmitter production. Using a combination of bioinformatics, recombinant cloning, enzymology, and proteomics, we have contributed to the understanding and exploration of several human illnesses, including malaria, cancer, and endocrine dysfunction.

Our first project involved studying the enzymes responsible for N-acylarylalkylamide biosynthesis in Bombyx mori. Very little is known how these potent signaling molecules are produced in vivo, however, one possible pathway is the direct conjugation of an acyl-CoA to a corresponding …


Spin Exchange Interaction In Substituted Copper Phthalocyanine Crystalline Thin Films, Naveen Rawat, Zhenwen Pan, Cody J. Lamarche, Anthony Wetherby, Rory Waterman, Takahisa Tokumoto, Judy G. Cherian Nov 2015

Spin Exchange Interaction In Substituted Copper Phthalocyanine Crystalline Thin Films, Naveen Rawat, Zhenwen Pan, Cody J. Lamarche, Anthony Wetherby, Rory Waterman, Takahisa Tokumoto, Judy G. Cherian

College of Arts and Sciences Faculty Publications

All rights reserved. The origins of spin exchange in crystalline thin films of Copper Octabutoxy Phthalocyanine (Cu-OBPc) are investigated using Magnetic Circular Dichroism (MCD) spectroscopy. These studies are made possible by a solution deposition technique which produces highly ordered films with macroscopic grain sizes suitable for optical studies. For temperatures lower than 2K, the contribution of a specific state in the valence band manifold originating from the hybridized lone pair in nitrogen orbitals of the Phthalocyanine ring, bears the Brillouin-like signature of an exchange interaction with the localized d-shell Cu spins. A comprehensive MCD spectral analysis coupled with a molecular …


Interference-Free Gas-Phase Thermometry At Elevated Pressure Using Hybrid Femtosecond/Picosecond Rotational Coherent Anti- Stokes Raman Scattering, Joseph D. Miller, Chloe Elizabeth Dedic, Sukesh Roy, James R. Gord, Terrence R. Meyer Nov 2015

Interference-Free Gas-Phase Thermometry At Elevated Pressure Using Hybrid Femtosecond/Picosecond Rotational Coherent Anti- Stokes Raman Scattering, Joseph D. Miller, Chloe Elizabeth Dedic, Sukesh Roy, James R. Gord, Terrence R. Meyer

Terrence R Meyer

Rotational-level-dependent dephasing rates and nonresonant background can lead to significant uncertainties in coherent anti-Stokes Raman scattering (CARS) thermometry under high-pressure, lowtemperature conditions if the gas composition is unknown. Hybrid femtosecond/picosecond rotational CARS is employed to minimize or eliminate the influence of collisions and nonresonant background for accurate, frequency-domain thermometry at elevated pressure. The ability to ignore these interferences and achieve thermometric errors of <5% is demonstrated for N2 and O2 at pressures up to 15 atm. Beyond 15 atm, the effects of collisions cannot be ignored but can be minimized using a short probe delay (~6.5 ps) after Raman excitation, …


Fast-Framing Ballistic Imaging Of Velocity In An Aerated Spray, David Sedarsky, James Gord, Campbell Carter, Terrence R. Meyer, Mark Linne Nov 2015

Fast-Framing Ballistic Imaging Of Velocity In An Aerated Spray, David Sedarsky, James Gord, Campbell Carter, Terrence R. Meyer, Mark Linne

Terrence R Meyer

We describe further development of ballistic imaging adapted for the liquid core of an atomizing spray. To fully understand spray breakup dynamics, one must measure the velocity and acceleration vectors that describe the forces active in primary breakup. This information is inaccessible to most optical diagnostics, as the signal is occluded by strong scattering in the medium. Ballistic imaging mitigates this scattering noise, resolving clean shadowgram-type images of structures within the dense spray region. We demonstrate that velocity data can be extracted from ballistic images of a spray relevant to fuel-injection applications, by implementing a simple, targeted correlation method for …


Index-Matched Boundary Techniques For The Elimination Of Acoustical Resonances, Jack H. Parker, Bradley D. Duncan Nov 2015

Index-Matched Boundary Techniques For The Elimination Of Acoustical Resonances, Jack H. Parker, Bradley D. Duncan

Bradley D. Duncan

We extend the principle of optical index of refraction to apply the concept of acoustical index for transverse acoustical wave propagation in strings. The relationship between acoustical index and mass density of the acoustic material is developed. With this theoretical link established, classic index-matching techniques are explored at acoustical boundaries. Proper selection of boundary interface segments leads to the elimination of resonant vibrationalmodes that occur in rigidly supported strings, while maintaining the nonresonant vibration response.


Coupling Efficiencies For General Target Illumination Ladar Systems Incorporating Single Mode Optical Fiber Receivers, Christopher Brewer, Bradley Duncan, Kenneth Barnard, Edward Watson Nov 2015

Coupling Efficiencies For General Target Illumination Ladar Systems Incorporating Single Mode Optical Fiber Receivers, Christopher Brewer, Bradley Duncan, Kenneth Barnard, Edward Watson

Bradley D. Duncan

A rigorous method for modeling received power coupling efficiency (ηF/R) and transmitted power coupling efficiency (ηF/T) in a general-target-illumination ladar system is presented. For our analysis we concentrate on incorporating a single-mode optical fiber into the ladar return signal path. By developing expressions for both ηF/R and ηF/T for a simple, diffuse target, our model allows for varying range, beam size on target, target diameter, and coupling optics. Through numerical analysis ηF/R is shown to increase as the range to target increases and decrease as target diameter increases, and ηF/T is shown to decrease with target range. A baseline signal-to-noise …


Sensitivity Comparison Of Ladar Receivers Designed To Detect Glint Targets, Christopher D. Brewer, Bradley D. Duncan, Edward A. Watson Nov 2015

Sensitivity Comparison Of Ladar Receivers Designed To Detect Glint Targets, Christopher D. Brewer, Bradley D. Duncan, Edward A. Watson

Bradley D. Duncan

We present four receiver designs for a ladar system, based on an optical parametric amplifier, that is designed to collect returns from glint targets. After coupling the return energy into periodically poled lithium niobate, the target backscatter is detected with either an infrared camera or a CCD array. Assuming reasonable detector and system characteristics, the sensitivity of each design is then evaluated by setting the receiver SNR detection threshold equal to one and using the minimum transmitted energy as the figure of merit. Through numerical analysis, we show that an upconversion receiver followed by a visible CCD array offers the …


Parametric Extension Of The Classical Exposure Schedule Theory For Angle-Multiplexed Photorefractive Recording Using The Common-Aperture Beam Geometry, Mark Delong, Bradley Duncan, Jack Parker Nov 2015

Parametric Extension Of The Classical Exposure Schedule Theory For Angle-Multiplexed Photorefractive Recording Using The Common-Aperture Beam Geometry, Mark Delong, Bradley Duncan, Jack Parker

Bradley D. Duncan

The gradual reorientations in crystal geometry encountered during angle-multiplexed holographic recording with obliquely incident recording beams can create significant parametric exposure-time and recording-angle dependencies in both grating writing- and erasure-time constants. We present a parametric extension of the classically derived backward-recursion algorithm that compensates for the intermingling effects of recording geometry, writing-beam intensity variations, and unique crystal behavior. We present experimental data for a sequence of 301 holograms recorded with the goal of equal hologram strength and, separately, the same sequence recorded with the goal of equal hologram reconstruction intensity—which are different cases for a steeply incident readout beam.