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Full-Text Articles in Engineering

High Throughput, Automated Prediction Of Focusing Patterns For Inertial Microfluidics, Aditya Kommajosula, Jeong-Ah Kim, Wonhee Lee, Baskar Ganapathysubramanian Jan 2019

High Throughput, Automated Prediction Of Focusing Patterns For Inertial Microfluidics, Aditya Kommajosula, Jeong-Ah Kim, Wonhee Lee, Baskar Ganapathysubramanian

Mechanical Engineering Publications

Visual inspections for identifying focusing points in inertial microfluidic flows are prone to misinterpreting stable locations and focusing shifts in the case of non-trivial focusing patterns. We develop and deploy an approach for automating the calculation of focusing patterns for a general channel geometry, and thereby reduce the dependence on empirical/visual procedures to confirm the presence of stable locations. We utilize concepts from interpolation theory (to represent continuous force-fields using discrete points), and stability theory to identify "basins of attraction" and quantitatively identify stable equilibrium points. Our computational experiments reveal that predicting equilibrium points accurately requires upto ×10-20 times ...


Hybrid Optical Integrator Based On Silicon-On-Insulator Platform, Taewon Huh Jan 2019

Hybrid Optical Integrator Based On Silicon-On-Insulator Platform, Taewon Huh

Graduate Theses - Physics and Optical Engineering

A hybrid optical integrator is a recirculating loop that performs oversampling typically for analog input, using the cross-gain modulation (XGM) in a semiconductor optical amplifier (SOA). The modulated input signal changes the gain of the loop through XGM and thus modifies the loop accumulation. This thesis presents hybrid optical integrator for an all-optical analog-to-digital converter based on a silicon photonics platform. The device consists of silicon waveguides of dimension 220 × 500 nm (thick × width) and approximately 5 m optical loop length including fiber length, input and output grating couplers for 1550 nm signal, directional couplers, and external components (SOA, optical ...


Effect Of (Poly)Electrolytes On The Interfacial Assembly Of Peg Functionalized Gold Nanoparticles, Srikanth Nayak, Max Fieg, Wenjie Wang, Wei Bu, Surya Mallapragada, David Vaknin Jan 2019

Effect Of (Poly)Electrolytes On The Interfacial Assembly Of Peg Functionalized Gold Nanoparticles, Srikanth Nayak, Max Fieg, Wenjie Wang, Wei Bu, Surya Mallapragada, David Vaknin

Chemical and Biological Engineering Publications

We report on the effect of interpolymer complexes (IPCs) of poly(acrylic acid) (PAA) with poly(ethylene glycol) functionalized Au nanoparticles (PEG-AuNPs) as they assemble at the vapor-liquid interface, using surface sensitive synchrotron X-ray scattering techniques. Depending on the suspension pH, PAA functions both as a weak polyelectrolyte and a hydrogen bond donor, and these two roles affect the interfacial assembly of PEG-AuNPs differently. Above its isoelectric point, we find that PAA leads to the formation of a PEG-AuNPs monolayer at the interface with hexagonal structure. In the presence of high concentration of HCl (i.e., below the isoelectric point ...


A Review: Thermal Stability Of Methylammonium Lead Halide Based Perovskite Solar Cells, Tanzila Tasnim Ava, Abdullah Al Mamun, Sylvain Marsillac, Gon Namkoong Jan 2019

A Review: Thermal Stability Of Methylammonium Lead Halide Based Perovskite Solar Cells, Tanzila Tasnim Ava, Abdullah Al Mamun, Sylvain Marsillac, Gon Namkoong

Electrical & Computer Engineering Faculty Publications

Perovskite solar cells have achieved photo-conversion efficiencies greater than 20%, making them a promising candidate as an emerging solar cell technology. While perovskite solar cells are expected to eventually compete with existing silicon-based solar cells on the market, their long-term stability has become a major bottleneck. In particular, perovskite films are found to be very sensitive to external factors such as air, UV light, light soaking, thermal stress and others. Among these stressors, light, oxygen and moisture-induced degradation can be slowed by integrating barrier or interface layers within the device architecture. However, the most representative perovskite absorber material, CH3 ...


Call For Abstracts - Resrb 2019, July 8-9, Wrocław, Poland, Wojciech M. Budzianowski Dec 2018

Call For Abstracts - Resrb 2019, July 8-9, Wrocław, Poland, Wojciech M. Budzianowski

Wojciech Budzianowski

No abstract provided.


Imaging Stress And Magnetism At High Pressures Using A Nanoscale Quantum Sensor, S. Hsieh, P. Bhattacharyya, C. Zu, T. Mittiga, T. J. Smart, F. Machado, B. Kobrin, T. O. Hohn, N. Z. Rui, Mehdi Kamrani, S. Chatterjee, S. Choi, M. Zaletel, V. V. Struzhkin, J. E. Moore, Valery I. Levitas, R. Jeanloz, N. Y. Yao Dec 2018

Imaging Stress And Magnetism At High Pressures Using A Nanoscale Quantum Sensor, S. Hsieh, P. Bhattacharyya, C. Zu, T. Mittiga, T. J. Smart, F. Machado, B. Kobrin, T. O. Hohn, N. Z. Rui, Mehdi Kamrani, S. Chatterjee, S. Choi, M. Zaletel, V. V. Struzhkin, J. E. Moore, Valery I. Levitas, R. Jeanloz, N. Y. Yao

Aerospace Engineering Publications

Pressure alters the physical, chemical and electronic properties of matter. The development of the diamond anvil cell (DAC) enables tabletop experiments to investigate a diverse landscape of high-pressure phenomena ranging from the properties of planetary interiors to transitions between quantum mechanical phases. In this work, we introduce and utilize a novel nanoscale sensing platform, which integrates nitrogen-vacancy (NV) color centers directly into the culet (tip) of diamond anvils. We demonstrate the versatility of this platform by performing diffraction-limited imaging (~600 nm) of both stress fields and magnetism, up to pressures ~30 GPa and for temperatures ranging from 25-340 K. For ...


Tunable Electronic And Optical Properties Of Low-Dimensional Materials, Shiyuan Gao Dec 2018

Tunable Electronic And Optical Properties Of Low-Dimensional Materials, Shiyuan Gao

Arts & Sciences Electronic Theses and Dissertations

Two-dimensional (2D) materials with single or a few atomic layers, such as graphene, hexagonal boron nitride (h-BN) and transition metal dichalcogenides (TMDCs), and the heterostructures or one-dimensional (1D) nanostructures they form, have attracted much attention recently as unique platforms for studying many condensed-matter phenomena and holds great potentials for nanoelectronics and optoelectronic applications. Apart from their unique intrinsic properties which has been intensively studied for over a decade by now, they also allow external control of many degrees of freedom, such as electrical gating, doping and layer stacking. In this thesis, I present a theoretical study of the electronic and ...


Optical Micro-Seismometer Based On Evanescent Field Perturbation Of Whispering Gallery Modes, Jaime Da Silva Dec 2018

Optical Micro-Seismometer Based On Evanescent Field Perturbation Of Whispering Gallery Modes, Jaime Da Silva

Mechanical Engineering Research Theses and Dissertations

This thesis proposes a light-weight, compact, and accurate optical micro-seismometer that could be used in many applications, such as planetary exploration. The sensor proposed here is based on the principle of whispering gallery optical mode (WGM) resonance shifts of a dielectric micro-resonator due to disturbances of its evanescent field. The micro-seismometer could be used in place of the traditional bulky seismometers. The design of a waveguide-resonator and mechanical structure to disturb the evanescent field are presented. A proof-of-concept a seismometer model that uses a 5µm ring resonator is numerically tested with actual seismic data. The results show that a WGM-based ...


First Observation Of P-Odd Gamma Asymmetry In Polarized Neutron Capture On Hydrogen, D. Blyth, J. Fry, N. Fomin, R. Alarcon, L. Alonzi, E. Askanazi, S. Baeßler, S. Balascuta, L. Barrón-Palos, Alex Barzilov, J. D. Bowman, N. Birge, J. R. Calarco, T. E. Chupp, V. Cianciolo, C. E. Coppola, C. B. Crawford, K. Craycraft, D. Evans, C. Fieseler, E. Frlež, I. Garishvili, M. T. W. Gericke, R. C. Gillis, K. B. Grammer, G. L. Greene, J. Hall, J. Hamblen, C. Hayes, E. B. Iverson, M. L. Kabir Dec 2018

First Observation Of P-Odd Gamma Asymmetry In Polarized Neutron Capture On Hydrogen, D. Blyth, J. Fry, N. Fomin, R. Alarcon, L. Alonzi, E. Askanazi, S. Baeßler, S. Balascuta, L. Barrón-Palos, Alex Barzilov, J. D. Bowman, N. Birge, J. R. Calarco, T. E. Chupp, V. Cianciolo, C. E. Coppola, C. B. Crawford, K. Craycraft, D. Evans, C. Fieseler, E. Frlež, I. Garishvili, M. T. W. Gericke, R. C. Gillis, K. B. Grammer, G. L. Greene, J. Hall, J. Hamblen, C. Hayes, E. B. Iverson, M. L. Kabir

Mechanical Engineering Faculty Publications

We report the first observation of the parity-violating gamma-ray asymmetry A(gamma)(np) in neutron-proton capture using polarized cold neutrons incident on a liquid parahydrogen target at the Spallation Neutron Source at Oak Ridge National Laboratory. A(gamma)(np) isolates the Delta I = 1, S-3(1)-> P-3(1) component of the weak nucleon-nucleon interaction, which is dominated by pion exchange and can be directly related to a single coupling constant in either the DDH meson exchange model or pionless effective field theory… See full text for full abstract.


Improved Gas Sensing Performance Of Ald Azo 3-D Coated Zno Nanorods, P. Lin, X. Chen, K. Zhang, H. Baumgart Dec 2018

Improved Gas Sensing Performance Of Ald Azo 3-D Coated Zno Nanorods, P. Lin, X. Chen, K. Zhang, H. Baumgart

Electrical & Computer Engineering Faculty Publications

This paper reports an enhancement on the sensing performance of ZnO nanorod ethanol sensors with a new approach by utilizing nested coatings of Aluminum doped ZnO (AZO) thin films by Atomic Layer Deposition (ALD) technology. ZnO nanorods were grown by the hydrothermal method with the ZnO seed layer synthesized on Silicon wafers by ALD. To enhance the sensing performance of ZnO nanorod ethanol sensors, multiple coated AZO thin film 3-D coatings were deposited on the surface of the intrinsic ZnO nanorods by ALD.To investigate the sensing performance of the ZnO nanorods sensor for the detection of ethanol vapor, a ...


Application Of Silicon Nanohair Textured P-N Junctions In A Photovoltaic Device, Michael Small Dec 2018

Application Of Silicon Nanohair Textured P-N Junctions In A Photovoltaic Device, Michael Small

Electronic Theses and Dissertations

The goal of this project is to design and develop a fabrication process for a silicon photovoltaic device which incorporates a nanohair textured p-n junction. The silicon nanowires are etched into a silicon wafer, comprising an epitaxial p-layer on n-substrate, via metal-assisted chemical etching (MACE). The resulting nanowires contain p-n junctions that lie along the length of the vertical nanowires. This construct has the potential to increase the optical bandwidth of a silicon photovoltaic device by allowing a greater amount of short wavelength light to reach the junction. In addition, the MACE method of nanofabrication has the potential for decreasing ...


Fabrication And Characterization Of Electrochemical Glucose Sensors, Mohammed Marie Dec 2018

Fabrication And Characterization Of Electrochemical Glucose Sensors, Mohammed Marie

Theses and Dissertations

Electrochemical sensors based on the nanostructure of the semiconductor materials are of tremendous interest to be utilized for glucose monitoring. The sensors, based on the nanostructure of the semiconductor materials, are the third generations of the glucose sensors that are fast, sensitive, and cost-effect for glucose monitoring.

Glucose sensors based on pure zinc oxide nanorods (NRs) grown on different substrates, such ITO, FTO, and Si/SiO2/Au, were investigated in this research. Silicon nanowire (NW)- based glucose sensors were also studied. First, an enzyme-based glucose sensor was fabricated out of glass/ITO/ZnO NRs/BSA/GOx/nafion membrane. The sensor ...


Quasi-Particle Band Structure And Excitonic Effects In One-Dimensional Atomic Chains, Eesha Sanjay Andharia Dec 2018

Quasi-Particle Band Structure And Excitonic Effects In One-Dimensional Atomic Chains, Eesha Sanjay Andharia

Theses and Dissertations

The high exciton binding energy in one dimensional (1D) nano-structures makes them prominent for optoelectronic device applications, making it relevant to theoretically investigate their electronic and optical properties. Many-body effects that are not captured by the conventional density functional theory (DFT) have a huge impact in such selenium and tellurium single helical atomic chains. This work goes one step beyond DFT to include the electron self-energy effects within the GW approximation to obtain a corrected quasi-particle electronic structure. Further, the Bethe-Salpeter equation was solved to obtain the absorption spectrum and to capture excitonic effects. Results were obtained using the Hyberstein-Louie ...


Exfoliation, Synthesis, And Characterization Of Nanoscale Te, Takayuki Hironaka Dec 2018

Exfoliation, Synthesis, And Characterization Of Nanoscale Te, Takayuki Hironaka

Theses and Dissertations

Since the experimental discovery of graphene, two dimensional materials have enjoyed more attention and emphasis in academic research than nanowires, but the latter are an important area of study for creating 1D materials, or single atom chains, the next generation materials for advancing electronic devices. Atomically thin layers can be generated from 2D materials with weak bonds in one direction, and by applying this concept to one dimensional weakly bonded materials, we hypothesize that single atom chains with atomic-scale diameters may be produced. Tellurium (Te) and selenium (Se) have lattices consisting of spiral chains oriented along the c-axis, and each ...


Fatigue Performance And Shear Demand Distributions Of Clustered Shear Connectors In Composite Bridge Girders, Brian David Hillhouse Dec 2018

Fatigue Performance And Shear Demand Distributions Of Clustered Shear Connectors In Composite Bridge Girders, Brian David Hillhouse

Theses and Dissertations

The current American Association of State Highway and Transportation Officials (AASHTO) Bridge Specifications assumes uniform shear flow demands at the steel-concrete interface of composite bridge girders. As stud pitch increases to beyond 24 in or as studs become clustered to account for pre-cast concrete decks, this assumed shear demand distribution may be unrepresentative. Understanding shear transfer and resulting demands on headed studs in composite beams are important for ensuring adequate composite design. This study investigates stud demands in composite bridge girders using large-scale fatigue testing and direct pressure measurements for stud force calculations. In this study, two large-scale composite beam ...


Cementitious Sensors Exhibiting Stopbands In Acoustic Transmission Spectra, Shreya Vemuganti Nov 2018

Cementitious Sensors Exhibiting Stopbands In Acoustic Transmission Spectra, Shreya Vemuganti

Shared Knowledge Conference

Ultrasonic monitoring in cementitious materials is challenging due to the high degree of attenuation. In wellbore environments, monitoring becomes more challenging due to inaccessibility. Meta materials, also known as acoustic bandgap materials, exhibit an interesting feature of forbidding the propagation of elastic/sound waves and isolate vibration in a certain frequency band. Traditionally, acoustic bandgap materials are developed with inclusions such as tin, aluminum, gold, steel in a polymer matrix. In this study, we present the development of three-dimensional cementitious sensors capable of exhibiting stopbands in the acoustic transmission spectra using carbon nanotubes. Relatively wide stopbands were engineered using Floquet-Bloch ...


Pulsed Fiber Optics Lasers As Highly Sensitive Sensors, Hanieh Afkhamiardakani Nov 2018

Pulsed Fiber Optics Lasers As Highly Sensitive Sensors, Hanieh Afkhamiardakani

Shared Knowledge Conference

An interferometer or resonator is a device in which optical beams of specific frequencies circulate with minimal losses. These losses are completely compensated by the gain inside a laser resonator. A small perturbation introduced inside the laser can affect its frequency, which in turns becomes a metric of that perturbation. The perturbation is usually caused by an electric or magnetic field, rotation, acceleration, nonlinear index of refraction etc. Tiny changes of optical frequency are monitored by superimposing the laser field and a reference field (from the same laser) on a detector. This technique requires creating a laser in which two ...


Genetic Algorithm Design Of Photonic Crystals For Energy-Efficient Ultrafast Laser Transmitters, Troy A. Hutchins-Delgado Nov 2018

Genetic Algorithm Design Of Photonic Crystals For Energy-Efficient Ultrafast Laser Transmitters, Troy A. Hutchins-Delgado

Shared Knowledge Conference

Photonic crystals allow light to be controlled and manipulated such that novel photonic devices can be created. We are interested in using photonic crystals to increase the energy efficiency of our semiconductor whistle-geometry ring lasers. A photonic crystal will enable us to reduce the ring size, while maintaining confinement, thereby reducing its operating power. Photonic crystals can also exhibit slow light that will increase the interaction with the material. This will increase the gain, and therefore, lower the threshold for lasing to occur. Designing a photonic crystal for a particular application can be a challenge due to its number of ...


Heat Transfer Comparison Of Varied Pebble Sizes And Packing Arrangements In A Pebble-Bed Reactor, Julian Spangler Nov 2018

Heat Transfer Comparison Of Varied Pebble Sizes And Packing Arrangements In A Pebble-Bed Reactor, Julian Spangler

Georgia Undergraduate Research Conference (GURC)

Pebble bed reactors are more cost efficient when heat transfer is optimized. In a pebble-bed reactor, optimizing heat transfer involves the analysis of complex flow. Therefore, computational fluid dynamics was used to simulate fluid movement in a structured cubic packing arrangement with a purpose in finding an optimal size of pebbles that will yield the fastest rate of heat transfer. The simple cubic pebble arrangement was used to determine if pebble size was key to optimizing heat transfer in the reactor. More complex arrangements of pebbles were used as comparison to the simple cubic packing in order to determine if ...


Lattice Instability During Solid-Solid Structural Transformations Under A General Applied Stress Tensor: Example Of Si I → Si Ii With Metallization, Nikolai A. Zarkevich, Hao Chen, Valery I. Levitas, Duane D. Johnson Oct 2018

Lattice Instability During Solid-Solid Structural Transformations Under A General Applied Stress Tensor: Example Of Si I → Si Ii With Metallization, Nikolai A. Zarkevich, Hao Chen, Valery I. Levitas, Duane D. Johnson

Aerospace Engineering Publications

The density functional theory was employed to study the stress-strain behavior and elastic instabilities during the solid-solid phase transformation (PT) when subjected to a general stress tensor, as exemplified for semiconducting Si I and metallic Si II, where metallization precedes the PT, so stressed Si I can be a metal. The hydrostatic PT occurs at 76 GPa, while under uniaxial loading it is 11 GPa (3.7 GPa mean pressure), 21 times lower. The Si I → Si II PT is described by a critical value of the phase-field’s modified transformation work, and the PT criterion has only two parameters ...


Fluted Films, Nathan B. Speirs, Mohammad M. Mansoor, Jesse Belden, Randy C. Hurd, Zhao Pan, Tadd T. Truscott Oct 2018

Fluted Films, Nathan B. Speirs, Mohammad M. Mansoor, Jesse Belden, Randy C. Hurd, Zhao Pan, Tadd T. Truscott

Mechanical and Aerospace Engineering Faculty Publications

This paper is associated with a poster winner of a 2017 APS/DFD Milton van Dyke Award for work presented at the DFD Gallery of Fluid Motion. The original poster is available from the Gallery of Fluid Motion, https://doi.org/10.1103/APS.DFD.2017.GFM.P0030


Bipartite Quantum Interactions: Entangling And Information Processing Abilities, Siddhartha Das Oct 2018

Bipartite Quantum Interactions: Entangling And Information Processing Abilities, Siddhartha Das

LSU Doctoral Dissertations

The aim of this thesis is to advance the theory behind quantum information processing tasks, by deriving fundamental limits on bipartite quantum interactions and dynamics. A bipartite quantum interaction corresponds to an underlying Hamiltonian that governs the physical transformation of a two-body open quantum system. Under such an interaction, the physical transformation of a bipartite quantum system is considered in the presence of a bath, which may be inaccessible to an observer. The goal is to determine entangling abilities of such arbitrary bipartite quantum interactions. Doing so provides fundamental limitations on information processing tasks, including entanglement distillation and secret key ...


How To Establish Successful Cooperative Student Learning Centers For Stem Courses, Ronald James Bieniek, Douglas R. Carroll, Cesar Mendoza, Oran Allan Pringle, Ekkehard Sinn, Kai-Tak Wan, Donald C. Wunsch Oct 2018

How To Establish Successful Cooperative Student Learning Centers For Stem Courses, Ronald James Bieniek, Douglas R. Carroll, Cesar Mendoza, Oran Allan Pringle, Ekkehard Sinn, Kai-Tak Wan, Donald C. Wunsch

Donald C. Wunsch

Students learn more if they are actively involved in the learning process, particularly in a cooperative manner. Several UMR faculty have operated course-based learning centers (LCs) as part of the campus-wide Learning Enhancement Across Disciplines (LEAD) Program of student learning assistance and enhancement. LCs are designed to assist large numbers of students in a cost- and time-efficient manner that promotes student engagement without requiring undue amounts of faculty time. Course instructors spend time in the open learning environment of the LC, in lieu of office hours, guiding students to master course material and skills in their evolution from novice to ...


Interface Model Of Pem Fuel Cell Membrane Steady-Dtate Behavior, Russell L. Edwards, Ayodeji Demuren Oct 2018

Interface Model Of Pem Fuel Cell Membrane Steady-Dtate Behavior, Russell L. Edwards, Ayodeji Demuren

Mechanical & Aerospace Engineering Faculty Publications

Modeling works which simulate the proton-exchange membrane fuel cell with the computational fluid dynamics approach involve the simultaneous solution of multiple, interconnected physics equations for fluid flows, heat transport, electrochemical reactions, and both protonic and electronic conduction. Modeling efforts vary by how they treat the physics within and adjacent to the membrane-electrode assembly (MEA). Certain approaches treat the MEA not as part of the computational domain, but rather an interface connecting the anode and cathode computational domains. These approaches may lack the ability to consistently model catalyst layer losses and MEA ohmic resistance. This work presents an upgraded interface formulation ...


Current-Driven Production Of Vortex-Antivortex Pairs In Planar Josephson Junction Arrays And Phase Cracks In Long-Range Order, Francisco Estellés-Duart, Miguel Ortuño, Andrés M. Somoza, Valerii M. Vinokur, Alex Gurevich Oct 2018

Current-Driven Production Of Vortex-Antivortex Pairs In Planar Josephson Junction Arrays And Phase Cracks In Long-Range Order, Francisco Estellés-Duart, Miguel Ortuño, Andrés M. Somoza, Valerii M. Vinokur, Alex Gurevich

Physics Faculty Publications

Proliferation of topological defects like vortices and dislocations plays a key role in the physics of systems with long-range order, particularly, superconductivity and superfluidity in thin films, plasticity of solids, and melting of atomic monolayers. Topological defects are characterized by their topological charge reflecting fundamental symmetries and conservation laws of the system. Conservation of topological charge manifests itself in extreme stability of static topological defects because destruction of a single defect requires overcoming a huge energy barrier proportional to the system size. However, the stability of driven topological defects remains largely unexplored. Here we address this issue and investigate numerically ...


No2- And No3- Enhance Cold Atmospheric Plasma Induced Cancer Cell Death By Generation Of Onoo-, Dehui Xu, Qingjie Cui, Yujing Xu, Zhijie Liu, Zeyu Chen, Wenjie Xia, Hao Zhang, Dingxin Liu, Hailan Chen, Michael G. Kong Oct 2018

No2- And No3- Enhance Cold Atmospheric Plasma Induced Cancer Cell Death By Generation Of Onoo-, Dehui Xu, Qingjie Cui, Yujing Xu, Zhijie Liu, Zeyu Chen, Wenjie Xia, Hao Zhang, Dingxin Liu, Hailan Chen, Michael G. Kong

Bioelectrics Publications

Cold atmospheric plasma (CAP) is a rapidly developed technology that has been widely applied in biomedicine especially in cancer treatment. Due to the generation of various active species in plasma, CAP could induce various tumor cells death and showed a promising potential in cancer therapy. To enhance the biological effects of gas plasma, changing the discharging parameters is the most commonly used method, yet increasing discharging power will lead to a higher possibility of simultaneously damage surrounding tissues. In this study, by adding nontoxic concentration of additional nitrite and nitrate in the medium, we found that anti-tumor effect of CAP ...


Indirect Imaging Using Computational Imaging Techniques, Aparna Viswanath Oct 2018

Indirect Imaging Using Computational Imaging Techniques, Aparna Viswanath

Electrical Engineering Theses and Dissertations

The work describes various methods employed towards solving the problem of indirect imaging. Computational techniques are employed to indirectly decipher information about an object hidden from view of a camera. Notion of virtualizing the source of illumination and detectors on real world rough surfaces was exploited to construct a non line of sight computational imager. Diversity was explored from the stand point of both illumination of the object and imaging of light reflected from the object. To understand the impact of scattering by real world rough surfaces, an instrument was developed that allows characterization of isoplanatic angle for different surface ...


Tailoring The Asymmetric Magnetoimpedance Response In Exchange-Biased Ni - Fe Multilayers, Ufuk Kilic, Carolina Ross, Carlos Garcia Sep 2018

Tailoring The Asymmetric Magnetoimpedance Response In Exchange-Biased Ni - Fe Multilayers, Ufuk Kilic, Carolina Ross, Carlos Garcia

Ufuk Kilic

The dependence of the asymmetric magnetoimpedance (MI) response on the directions of both the magnetic field and the exchange bias is studied for an [NiFe(60nm)/IrMn(35nm)]×5 multilayer system. The antiferromagnetic (AFM) layers create an exchange bias that shifts both the hysteresis loop and the MI response of NiFe; the strength of this coupling depends on the thicknesses of both the ferromagnetic layer and the AFM layer. Tuning the exchange-bias angle and the applied-magnetic-field direction provides a practical method to control the symmetry and the magnitude of the MI response. The observed asymmetric response can ...


Disorder-Driven Transition From S(+/-) To S(+ +) Superconducting Order Parameter In Proton Irradiated Ba(Fe1-Xrhx)(2)As-2 Single Crystals, G. Ghigo, D. Torsello, G. A. Ummarino, L. Gozzelino, Makariy A. Tanatar, Ruslan Prozorov, Paul C. Canfield Sep 2018

Disorder-Driven Transition From S(+/-) To S(+ +) Superconducting Order Parameter In Proton Irradiated Ba(Fe1-Xrhx)(2)As-2 Single Crystals, G. Ghigo, D. Torsello, G. A. Ummarino, L. Gozzelino, Makariy A. Tanatar, Ruslan Prozorov, Paul C. Canfield

Ames Laboratory Accepted Manuscripts

Microwave measurements of the London penetration depth and critical temperature T c were used to show evidence of a disordered-driven transition from s ± to s + + order parameter symmetry in optimally doped Ba ( Fe 1 − x Rh x ) 2 As 2 single crystals, where disorder was induced by means of 3.5 MeV proton irradiation. Signatures of such a transition, as theoretically predicted [V. D. Efremov et al., Phys. Rev. B 84, 180512(R) (2011)], are found as a drop in the low-temperature values of the London penetration depth and a virtually disorder-independent superconducting T c . We show how these experimental ...


Application Of Spectral Solution And Neural Network Techniques In Plasma Modeling For Electric Propulsion, Joseph R. Whitman Sep 2018

Application Of Spectral Solution And Neural Network Techniques In Plasma Modeling For Electric Propulsion, Joseph R. Whitman

Theses and Dissertations

A solver for Poisson's equation was developed using the Radix-2 FFT method first invented by Carl Friedrich Gauss. Its performance was characterized using simulated data and identical boundary conditions to those found in a Hall Effect Thruster. The characterization showed errors below machine-zero with noise-free data, and above 20% noise-to-signal strength, the error increased linearly with the noise. This solver can be implemented into AFRL's plasma simulator, the Thermophysics Universal Research Framework (TURF) and used to quickly and accurately compute the electric field based on charge distributions. The validity of a machine learning approach and data-based complex system ...