Physical Sciences and Mathematics Commons^™

Eyes App Goes To The White House, Robert E. Gutsche Jr.

Sea Level Rise Collection

No abstract provided.

Interstitial Silicon Ions In Rutile Tio2 Crystals, Eric M. Golden, Nancy C. Giles, Shan Yang, Larry E. Halliburton

Faculty Publications

Electron paramagnetic resonance (EPR) is used to identify a new and unique photoactive silicon-related point defect in single crystals of rutile TiO₂. The importance of this defect lies in its assignment to interstitial silicon ions and the unexpected establishment of silicon impurities as a major hole trap in TiO₂. Principal g values of this new S=1/2 center are 1.9159, 1.9377, and 1.9668 with principal axes along the [¯110],[001], and [110] directions, respectively. Hyperfine structure in the EPR spectrum shows the unpaired spin interacting equally with two Ti nuclei and unequally with two Si nuclei. These silicon …

Stellar Spectroscopy: New Methods And Insights, Sanaz S. Golriz

Electronic Thesis and Dissertation Repository

The study of the chemical evolution of stars is of crucial importance since they play a major role in the enrichment of the chemistry of the universe. Throughout their lifetime, stars undergo several processes that can alter their chemistry. Gradually, the nucleosynthesis products from the interior of the star are radiatively and convectively levitated and mixed with the upper layers of the atmosphere. In the later stages of their evolution, low to intermediate mass stars (0.8-8.0~M☉) eject a significant fraction of these nucleosynthesis products, resulting in a circumstellar envelope of gas and dust around the central star with a very …

Physical Properties And Behaviour Of Highly Bi-Substituted Magneto-Optic Garnets For Applications In Integrated Optics And Photonics, Mohammad Nur E Alam, Mikhail Vasiliev, Kamal Alameh, Viacheslav Kotov

Mikhail Vasiliev

Rare-earth and Bi-substituted iron garnet thin film materials exhibit strong potential for application in various fields of science and frontier optical technologies. Bi-substituted iron garnets possess extraordinary optical and MO properties and are still considered as the best MO functional materials for various emerging integrated optics and photonics applications. However, these MO garnet materials are rarely seen in practical photonics use due to their high optical losses in the visible spectral region. In this paper, we report on the physical properties and magneto-optic behaviour of high-performance RF sputtered highly bismuth-substituted iron garnet and garnet-oxide nanocomposite films of generic composition type …

Highly Bismuth-Substituted, Record-Performance Magneto-Optic Garnet Materials With Low Coercivity For Applications In Integrated Optics, Photonic Crystals, Imaging And Sensing, Mohammad Nur E Alam, Mikhail Vasiliev, Viacheslav A Kotov, Kamal Alameh

Mikhail Vasiliev

We report on the fabrication of radio frequency (RF) sputtered Bi-substituted lutetium iron garnet films doped with aluminum and the results of adjusting the properties of these films by means of co-sputtering deposition using an additional bismuth oxide target. Very attractive optical, magnetic and magneto-optical properties are achieved in these new magneto-optic materials. The high-performance magnetically-soft thin-film engineered materials synthesized have a wide range of potential applications in next-generation integrated optics, magneto-photonics and magnetic field sensors.

Synthesis Of High-Performance Magnetic Garnet Materials And Garnet-Bismuth Oxide Nanocomposites Using Physical Vapor Deposition Followed By High-Temperature Crystallization, Mohammad Nur E Alam, Mikhail Vasiliev, Kamal Alameh, Viacheslav Kotov

Mikhail Vasiliev

Bi-substituted iron garnet (Bi:IG) compounds synthesized in thin film form are the best semi-transparent magneto-optical (MO) materials for applications in magnetic recording, optical sensors, and photonics. These materials can possess attractive magnetic properties and the highest specific Faraday rotation in the visible and near-infrared spectral regions, if the deposited layers contain a high volumetric fraction of the garnet phase and possess high-quality surfaces and microstructure. In this paper, we study the effects of various deposition and annealing process parameters on the properties of Bi:IG and garnet-oxide nanocomposite films of several composition types fabricated using radio-frequency (RF) sputtering deposition followed by …

Spatially Resolved Inhomogeneous Depressions Of The Excitons Zeeman Splitting In An Integrated Magnetic-Multiple Quantum Wells System, Ahmed Abdelrahman, Hoon Soo Kang, Sang Youp Yim, Mikhail Vasiliev, Kamal Alameh, Yong Lee

Mikhail Vasiliev

We report on the generation of a nonuniform spatial distribution of the heavy and light-hole excitons in a multiple quantum wells system integrated with a localized inhomogeneous weak magnetic field. An inhomogeneous spatially resolved depression of the Zeeman splittings of the heavy-hole excitons and the light-hole excitons with respect to their translational wave vectors is observed. A localized inverted concentration of the two types of the excitons due to the inhomogeneity of the magnetic field is also measured. A simple method to integrate permanent magnetic materials with the multiple quantum wells system is used to create an accessible degree of …

Inhomogeneous Spin-Dependent Spatial Distribution Of Excitons In An Integrated Magnetic-Multiple Quantum Wells System., Ahmed Abdelrahman, Hansoon Kang, Mikhail Vasiliev, Kamal Alameh, Yong Lee

Mikhail Vasiliev

We report on the observation of an inhomogeneous spin-dependent spatial distribution of heavy-hole excitons generated by a localized inhomogeneous magnetic weak eld. An exciton energy splitting is observed between the spin-up and spin-down states with an energy gap as a function of the magnetic field

Metal-Semiconductor-Metal (Msm) Photodetectors With Plasmonic Nanogratings, Narottam K. Das, Ayman Karar, C L Tan, Mikhail Vasiliev, Kamal Alameh, Yong Tak Lee

Mikhail Vasiliev

We discuss the light absorption enhancement factor dependence on the design of nanogratings inscribed into metal-semiconductor-metal photodetector (MSM-PD) structures. These devices are optimized geometrically, leading to light absorption improvement through plasmon-assisted effects. Finite-difference time-domain (FDTD) simulation results show ~50 times light absorption enhancement for 850 nm light due to improved optical signal propagation through the nanogratings. Also, we show that the light absorption enhancement is strongly dependent on the nanograting shapes in MSM-PDs.

Physical Properties And Behaviour Of Highly Bi-Substituted Magneto-Optic Garnets For Applications In Integrated Optics And Photonics, Mohammad Nur E Alam, Mikhail Vasiliev, Kamal Alameh, Viacheslav Kotov

Mikhail Vasiliev

Rare-earth and Bi-substituted iron garnet thin film materials exhibit strong potential for application in various fields of science and frontier optical technologies. Bi-substituted iron garnets possess extraordinary optical and MO properties and are still considered as the best MO functional materials for various emerging integrated optics and photonics applications. However, these MO garnet materials are rarely seen in practical photonics use due to their high optical losses in the visible spectral region. In this paper, we report on the physical properties and magneto-optic behaviour of high-performance RF sputtered highly bismuth-substituted iron garnet and garnet-oxide nanocomposite films of generic composition type …

Annealing Behaviour And Crystal Structure Of Rf-Sputtered Bi-Substituted Dysprosium Iron-Garnet Films Having Excess Co-Sputtered Bi-Oxide Content, Mikhail Vasiliev, Mohammad Nur-E-Alam, Kamal Alameh, P Premchander, Yong Lee, V Kotov, Y Lee

Mikhail Vasiliev

We investigate the magneto-optic properties, crystal structure and annealing behaviour of nano-composite media with record-high magneto-optic quality exceeding the levels reported so far in sputtered iron-garnet films. Bi-substituted dysprosium–gallium iron-garnet films having excess bismuth oxide content are deposited using RF co-sputtering, and a range of garnet materials are crystallized using conventional oven-annealing processes. We report, for the first time ever, the results of optimization of thermal processing regimes for various high-performance magneto-optic iron-garnet compositions synthesized and describe the evolution of the optical and magneto-optical properties of garnet-Bi-oxide composite-material films occurring during the annealing processes. The crystallization temperature boundaries of the …

Magnetic Micro-Trapping Of Excitons In Multiple Quantum Wells System Using Local Field Minima, Ahmed Abdelrahman, Hansoon Kang, Mikhail Vasiliev, Kamal Alameh

Mikhail Vasiliev

We propose a simple method to create a local magnetic field minima for the magnetic trapping and confining of excitons. We observe an enhanced spatially resolved photoluminescence of the optically active heavy-hole excitons concentrated at the confining region in a multiple quantum wells system. We draw the attention to consider the proposed trapping mechanism as an approach to reach the Bose-Einstein condensate limit of excitons.

Highly Bismuth-Substituted, Record-Performance Magneto-Optic Garnet Materials With Low Coercivity For Applications In Integrated Optics, Photonic Crystals, Imaging And Sensing, Mohammad Nur E Alam, Mikhail Vasiliev, Viacheslav A Kotov, Kamal Alameh

Mikhail Vasiliev

We report on the fabrication of radio frequency (RF) sputtered Bi-substituted lutetium iron garnet films doped with aluminum and the results of adjusting the properties of these films by means of co-sputtering deposition using an additional bismuth oxide target. Very attractive optical, magnetic and magneto-optical properties are achieved in these new magneto-optic materials. The high-performance magnetically-soft thin-film engineered materials synthesized have a wide range of potential applications in next-generation integrated optics, magneto-photonics and magnetic field sensors.

Synthesis Of High-Performance Magnetic Garnet Materials And Garnet-Bismuth Oxide Nanocomposites Using Physical Vapor Deposition Followed By High-Temperature Crystallization, Mohammad Nur E Alam, Mikhail Vasiliev, Kamal Alameh, Viacheslav Kotov

Mikhail Vasiliev

Bi-substituted iron garnet (Bi:IG) compounds synthesized in thin film form are the best semi-transparent magneto-optical (MO) materials for applications in magnetic recording, optical sensors, and photonics. These materials can possess attractive magnetic properties and the highest specific Faraday rotation in the visible and near-infrared spectral regions, if the deposited layers contain a high volumetric fraction of the garnet phase and possess high-quality surfaces and microstructure. In this paper, we study the effects of various deposition and annealing process parameters on the properties of Bi:IG and garnet-oxide nanocomposite films of several composition types fabricated using radio-frequency (RF) sputtering deposition followed by …

Spatially Resolved Inhomogeneous Depressions Of The Excitons Zeeman Splitting In An Integrated Magnetic-Multiple Quantum Wells System, Ahmed Abdelrahman, Hoon Soo Kang, Sang Youp Yim, Mikhail Vasiliev, Kamal Alameh, Yong Lee

Mikhail Vasiliev

We report on the generation of a nonuniform spatial distribution of the heavy and light-hole excitons in a multiple quantum wells system integrated with a localized inhomogeneous weak magnetic field. An inhomogeneous spatially resolved depression of the Zeeman splittings of the heavy-hole excitons and the light-hole excitons with respect to their translational wave vectors is observed. A localized inverted concentration of the two types of the excitons due to the inhomogeneity of the magnetic field is also measured. A simple method to integrate permanent magnetic materials with the multiple quantum wells system is used to create an accessible degree of …

Polarization Patterning By Laser-Induced Phase Change In Ferroelectric Polymer Films, Christina M. Othon, Stephen Ducharme

Christina M Othon

Polarization patterns were written on ferroelectric poly(vinylidene- trifluoroethylene) copolymer Langmuir–Blodgett films by heating into the paraelectric phase by laser illumination using two methods. In the first method, patterns were produced by direct writing by a focused continuouswave laser beam that was moved across the sample. This method affords the greatest flexibility. In the second method, the patterns were generated simultaneously with a pulsed laser using a beam interference method. This method produces highly regular patterns quickly over large areas and affords higher patterning resolution. The patterns produced by both methods could be erased and rewritten, making this technique useful for …

U.S. Drought Monitor, April 21, 2015, Anthony Artusa

United States Agricultural Commodities in Drought Archive

Drought map of U.S. for April 21, 2015 (4/21/15) plus: U.S. crop areas experiencing drought (map), Approximate percentage of crop located in drought, by state (bar graph), Percent of crop area located in drought, past 52 weeks (line graph) for: Corn, Soybeans, Hay, Cattle, Winter wheat.

Cosm News, Georgia Southern University

College of Science and Mathematics News (2012-2019)

• ICPS Summer Grad RA Awardees

Sensing Based On Fano-Type Resonance Response Of All-Dielectric Metamaterials, Elena Semouchkina, Ran Duan, George Semouchkin, Ravindra Pandey

Michigan Tech Publications

A new sensing approach utilizing Mie resonances in metamaterial arrays composed of dielectric resonators is proposed. These arrays were found to exhibit specific, extremely high-Q factor (up to 15,000) resonances at frequencies corresponding to the lower edge of the array second transmission band. The observed resonances possessed with features typical for Fano resonances (FRs), which were initially revealed in atomic processes and recently detected in macro-structures, where they resulted from interference between local resonances and a continuum of background waves. Our studies demonstrate that frequencies and strength of Fano-type resonances in all-dielectric arrays are defined by interaction between local Mie …

Ice Nucleation By Water-Soluble Macromolecules, B. G. Pummer, C. Budke, S. Augustin-Bauditz, D. Niedermeier, L. Felgitsch, C. J. Kampf, R. G. Huber, K. R. Liedl, T. Loerting, T. Moschen, M. Schauperl, M. Tollinger, C. E. Morris, H. Wex, H. Grothe, U. Pöschl, T. Koop, J. Fröhlich-Nowoisky

Michigan Tech Publications

Cloud glaciation is critically important for the global radiation budget (albedo) and for initiation of precipitation. But the freezing of pure water droplets requires cooling to temperatures as low as 235 K. Freezing at higher temperatures requires the presence of an ice nucleator, which serves as a template for arranging water molecules in an ice-like manner. It is often assumed that these ice nucleators have to be insoluble particles. We point out that also free macromolecules which are dissolved in water can efficiently induce ice nucleation: the size of such ice nucleating macromolecules (INMs) is in the range of nanometers, …

Hampton Roads Must Rise To Challenge In Reducing Effects Of Climate Change, Daily Press

News Items

No abstract provided.

Climate Activist Visits Fiu, Robert E. Gutsche Jr.

Sea Level Rise Collection

Announcement of visit by Captain Dan Kipnis to FIU.

Simple Secrecy: Analog Stream Cipher For Secure Voice Communication, John M. Campbell

Senior Honors Theses

Voice signals are inherently analog, and some voice communication systems still utilize analog signals. Existing analog cryptographic methods do not satisfactorily provide cryptosecurity for communication systems due to several limitations. This paper proposes a novel means of provided cryptosecurity for analog signals without digitization; thereby avoiding the latency which results from ADC/DAC conversions. This method utilizes the principles of the digital stream cipher, generating instead a continuous pseudorandom analog key stream signal which is transformed with the original analog signal to create an encrypted ciphertext signal which is statistically independent of the original signal and the key stream signal. The …

Properties Of Exchange Coupled All-Garnet Magneto-Optic Thin Film Multilayer Structures, Mohammad Nur-E-Alam, Mikhail Vasiliev, Viacheslav A. Kotov, Dmitry Balabanov, Ilya Akimov, Kamal Alameh

Mikhail Vasiliev

The effects of exchange coupling on magnetic switching properties of all-garnet multilayer thin film structures are investigated. All-garnet structures are fabricated by sandwiching a magneto-soft material of composition type Bi1.8Lu1.2Fe3.6Al1.4O12 or Bi3Fe5O12:Dy2O3 in between two magneto-hard garnet material layers of composition type Bi2Dy1Fe4Ga1O12 or Bi2Dy1Fe4Ga1O12:Bi2O3. The fabricated RF magnetron sputtered exchange-coupled all-garnet multilayers demonstrate a very attractive combination of magnetic properties, and are of interest for emerging applications in optical sensors and isolators, ultrafast nanophotonics and magneto-plasmonics. An unconventional type of magnetic hysteresis behavior not observed previously in magnetic garnet thin films is reported and discussed.

Teaching Cybersecurity Using The Cloud, Khaled Salah, Mohammad Hammoud, Sherali Zeadally

Information Science Faculty Publications

Cloud computing platforms can be highly attractive to conduct course assignments and empower students with valuable and indispensable hands-on experience. In particular, the cloud can offer teaching staff and students (whether local or remote) on-demand, elastic, dedicated, isolated, (virtually) unlimited, and easily configurable virtual machines. As such, employing cloud-based laboratories can have clear advantages over using classical ones, which impose major hindrances against fulfilling pedagogical objectives and do not scale well when the number of students and distant university campuses grows up. We show how the cloud paradigm can be leveraged to teach a cybersecurity course. Specifically, we share our …

Pattern Recognition For Detecting Failures In Space Solar Power Systems, Allen Mcdermott, Cameron Kerbaugh, Jeremy Straub, Eunjin Kim

Jeremy Straub

This poster covers work relating to the use of expert systems and pattern recognition to attempt to identify, detect and prospectively stop patterns of activity that could potentially lead to failure of a space solar power (SSP) system. A database-based expert system has is presented to identify patterns, which can be used to determine whether a power beam could hit a unintend- ed target and potentially cause a calamity. This has been implemented via a facts-rule network via which supplied and collected facts and a rule set is used to de- termine whether the system is operating correctly (from a …

A Seasonal Analysis Of Extreme Precipitation Trends In The Contiguous United States, Rachael Balstad, Jaechoul Lee

College of Arts and Sciences Presentations

The purpose of this paper is to examine extreme precipitation trends in the United States. The National Climate Assessment estimated that average precipitation in the United States has increased in the last 100 years, with variation occurring regionally. Some regions have experienced larger increases in average precipitation, while others have experienced decreases. However, this aggregate increase in average precipitation does not necessarily indicate an analogous trend in extreme precipitation. Statistically, average and extreme values are nearly independent. In this paper, a changepoint technique and extreme value statistical models will be used for estimation of trend and its uncertainty. A changepoint …

Zircon Chemistry In A Gabbro Pluton At House Mountain, Idaho, Danielle Terhaar, Mark Schmitz

College of Arts and Sciences Presentations

An Eocene (ca 45 million year old) gabbro pluton near House Mountain in southwest Idaho provides an opportunity to explore how the conditions of crystallization are recorded in zircon chemistry. Zircon is a zirconium silicate mineral present in trace amounts in magmas, which is capable of incorporating large, highly charged elements (e.g. transition metals, actinides, lanthanides) that do not easily substitute into other minerals. Variations in these elements can be used to track magma evolution. For example, the titanium concentration is related to the temperature at which zircon crystallizes from the magma; rare earth elements (REE) and the relative …

Reconstructing The Geologic History Of The House Mountain Metamorphic Complex (Southern Idaho) Through Zircon Age And Geochemical Analysis, Eli Andersen, Mark Schmitz

College of Arts and Sciences Presentations

Zircons from quartzo-feldspathic gneiss within the Precambrian (>725 Ma) siliciclastics of the House Mountain Metamorphic Complex of southwestern Idaho were studied to determine its origin and evolution. Cathodoluminescence imaging of internal zoning due to growth and recrystallization of zircon, along with laser ablation inductively coupled plasma mass spectrometer (LA-ICPMS) analysis of these zircons, reveal a complex history of metamorphism at House Mountain. Primary igneous crystallization in the orthogneiss occurred near 130 Ma. Convoluted regions of the zircons have ages ranging from 130 to 85 Ma. These younger ages are hypothesized to be related to lead loss and new crystal …

The Differences In The Torus Geometry Between Hidden And Non-Hidden Broad Line Active Galactic Nuclei, Kohei Ichikawa, Eric S. Perlman

Aerospace, Physics, and Space Science Faculty Publications

We present results from the fitting of infrared (IR) spectral energy distributions of 21 active galactic nuclei (AGNs) with clumpy torus models. We compiled high spatial resolution (∼0.3–0.7 arcsec) mid-IR (MIR) N-band spectroscopy, Q-band imaging, and nuclear near- and MIR photometry from the literature. Combining these nuclear near- and MIR observations, far-IR photometry, and clumpy torus models enables us to put constraints on the torus properties and geometry. We divide the sample into three types according to the broad line region (BLR) properties: type-1s, type-2s with scattered or hidden broad line region (HBLR) previously observed, and type-2s without any published …