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Effects Of Schmid Factor And Slip Nucleation On Deformation Mechanism In Columnar-Grained Nanotwinned Ag And Cu, Valery Borovikov, Mikhail I. Mendelev, Alexander H. King, Richard Lesar 2017 The Ames Laboratory

Effects Of Schmid Factor And Slip Nucleation On Deformation Mechanism In Columnar-Grained Nanotwinned Ag And Cu, Valery Borovikov, Mikhail I. Mendelev, Alexander H. King, Richard Lesar

Richard Alan Lesar

We report the results of a molecular dynamics study of the effect of texture on the yield and peak stresses in columnar-grained nanotwinned Ag and Cu. The simulations suggest that in pure nanotwinned face-centered cubic metals, the strength is determined primarily by the cooperation or competition between two major factors: the magnitude of the Schmid factors for the available slip systems and the effectiveness of grain boundaries (and their triple-junctions) in generating dislocations. These factors and their relative impact depend on the geometry of the specimen relative to the applied stress, which is typically reflected in the texture of the ...


Phenix Detector Overview, K. Adcox, Sergey Belikov, S. Bhagavatula, Paul Constantin, K. C. Cook, John C. Hill, John G. Lajoie, Alexandre Lebedev, B. Libby, Craig Ogilvie, A. N. Petridis, T. Plagge, Marzia Rosati, Harold D. Skank, S. Skutnik, G. A. Sleege, W. D. Thomas, T. Weimer, F. K. Wohn, L. Wood, et al. 2017 Vanderbilt University

Phenix Detector Overview, K. Adcox, Sergey Belikov, S. Bhagavatula, Paul Constantin, K. C. Cook, John C. Hill, John G. Lajoie, Alexandre Lebedev, B. Libby, Craig Ogilvie, A. N. Petridis, T. Plagge, Marzia Rosati, Harold D. Skank, S. Skutnik, G. A. Sleege, W. D. Thomas, T. Weimer, F. K. Wohn, L. Wood, Et Al.

Craig Ogilvie

The PHENIX detector is designed to perform a broad study of A–A, p–A, and p–p collisions to investigate nuclear matter under extreme conditions. A wide variety of probes, sensitive to all timescales, are used to study systematic variations with species and energy as well as to measure the spin structure of the nucleon. Designing for the needs of the heavy-ion and polarized-proton programs has produced a detector with unparalleled capabilities. PHENIX measures electron and muon pairs, photons, and hadrons with excellent energy and momentum resolution. The detector consists of a large number of subsystems that are discussed ...


Eddy-Current Probe Interaction With Subsurface Cracks, John R. Bowler 2017 University of Surrey

Eddy-Current Probe Interaction With Subsurface Cracks, John R. Bowler

John R. Bowler

Electric current will flow around on open crack in a conductor and give rise to very abrupt variations in the field. If the crack has a negligible opening it acts as a surface barrier where the field is virtually discontinuous. Effectively the crack is then equivalent to a layer of current dipoles with the dipole orientation normal to the surface and pointing upstream. An integral equation for the dipole density has been derived for an idealised subsurface crack using the Green’s function method [1]. Numerical solutions have been found by assuming a piecewise constant dipole density and satisfying boundary ...


Tracer Counterpermeation Analysis Of Diffusivity In Finite-Length Nanopores With And Without Single-File Dynamics, David Ackerman, James W. Evans 2017 Iowa State University

Tracer Counterpermeation Analysis Of Diffusivity In Finite-Length Nanopores With And Without Single-File Dynamics, David Ackerman, James W. Evans

James W. Evans

We perform a tracer counterpermeation (TCP) analysis for a stochastic model of diffusive transport through a narrow linear pore where passing of species within the pore is inhibited or even excluded (single-file diffusion). TCP involves differently labeled but otherwise identical particles from two decoupled infinite reservoirs adsorbing into opposite ends of the pore, and desorbing from either end. In addition to transient behavior, we assess steady-state concentration profiles, spatial correlations, particle number fluctuations, and diffusion fluxes through the pore. From the profiles and fluxes, we determine a generalized tracer diffusion coefficient Dtr(x), at various positions x within the pore ...


Relaxation Of Microwave Nonlinearity In A Cuprate Superconducting Resonator, Richard A. Huizen, Sean L. Hamilton, Geoffrey T. Lenters, Stephen K. Remillard 2017 Grand Valley State University

Relaxation Of Microwave Nonlinearity In A Cuprate Superconducting Resonator, Richard A. Huizen, Sean L. Hamilton, Geoffrey T. Lenters, Stephen K. Remillard

Faculty Publications

The second- and third-order nonlinear microwave response of a superconducting YBa2Cu3O7 thin-film resonator was synchronously measured using three input tones. This technique permits the local measurement, and hence mapping, of intermodulation distortion inside the resonator. Second- and third-order IMD measured with a fixed probe relaxed in remarkably different ways after the removal of a static magnetic field. The second-order IMD relaxed by two different magnetic processes, a fast process that appears related to bulk remanent magnetization and a slow process that fits the description of Bean and Livingston. The third-order IMD relaxes by only one process that is distinct from ...


A Period Examination Through Contemporary Energy Analysis Of Kevin Roche’S Fine Arts Center At University Of Massachusetts-Amherst, L Carl Fiocchi Jr 2017 University of Massachusetts - Amherst

A Period Examination Through Contemporary Energy Analysis Of Kevin Roche’S Fine Arts Center At University Of Massachusetts-Amherst, L Carl Fiocchi Jr

L. Carl Fiocchi

Studies of buildings belonging to a subset of Modernist architecture, Brutalism, have included discussions pertaining to social and architectural history, critical reception, tectonic form and geometry inspirations, material property selections, period technology limitations, and migration of public perceptions. Evaluations of Brutalist buildings’ energy related performances have been restricted to anecdotal observations with particular focus on the building type’s poor thermal performance, a result of the preferred construction method, i.e. monolithic reinforced concrete used as structure, interior finish and exterior finish. A valid criticism, but one that served to dismiss discussion that the possibility of other positive design strategies ...


Time-Resolved Thz Conductivity Of An Intermediate Band Semiconductor, Elliot Weiss 2017 Macalester College

Time-Resolved Thz Conductivity Of An Intermediate Band Semiconductor, Elliot Weiss

Macalester Journal of Physics and Astronomy

Intermediate band materials have promising applications as affordable, highly efficient solar materials. However, intermediate band solar cells exhibit low efficiency to date. Carrier recombination is a critical process that limits efficiency. If electrons relax to the valence band before they can be collected, their energy is lost. To help understand the recombination dynamics and physical properties of intermediate band semiconductors, we obtain time-resolved THz conductivity measurements of the intermediate band semiconductor, GaPAsN, at various temperatures. From our results, we build a model that provides insight to the recombination dynamics of GaPAsN.


Designing Novel Nanostructured Permanent Magnets, Ali Al Kadhim 2017 University of Nebraska at Omaha

Designing Novel Nanostructured Permanent Magnets, Ali Al Kadhim

Student Research and Creative Activity Fair

Rare earth element based alloys have been the source of high performance magnetic alloys, and have played a paramount role in the development of various technologies, including: memory devices (such as credit cards, random-access memory), sensors, and various biomedical applications. However, there is a tremendous need to replace rare earth metals with material with powerful magnetic properties. Our group recently found CrTe-based materials that show very promising magnetic properties in nanostructured form. The magnetic modeling of such material in nanostructured form prior to their fabrication demonstrates their magnetic properties in bulk form. In this project, we investigate the behavior of ...


Formation Of Mound-Like Multiscale Surface Structures On Titanium By Femtosecond Laser Processing, Edwin Peng, Alfred Tsubaki, Craig A. Zuhlke, Ryan Bell, Meiyu Wang, Dennis R. Alexander, George Gogos, Jeffrey E. Shield 2017 University of Nebraska-Lincoln

Formation Of Mound-Like Multiscale Surface Structures On Titanium By Femtosecond Laser Processing, Edwin Peng, Alfred Tsubaki, Craig A. Zuhlke, Ryan Bell, Meiyu Wang, Dennis R. Alexander, George Gogos, Jeffrey E. Shield

Mechanical (and Materials) Engineering -- Dissertations, Theses, and Student Research

Surface Functionalization Technique • Femtosecond Laser Surface Processing (FLSP) • Utilize high power, femtosecond (10-15 s) laser pulses • Produce self-organized, multiscale surface micro/nanostructures • Diverse range of applicable substrates: semiconductors, metals, polymers, & composites

Why? • What are the different types of FLSP structures on Ti? • Physical evidence needed for FLSP formation models • Optimize FLSP of Ti for biomedical & other applications

How? • Obtain evidence of mound growth processes by examining underlying microstructure • Utilize dual beam Scanning Electron Microscope-Focused Ion Beam instrument to cross section surface structures & fabricate transmission electron microscopy samples


Low-Density Self-Driven Electromagnetic Wheel: Comparison Of Different Tracks, Nathan GR Gaul, Walerian Majewski 2017 Northern Virginia Community College

Low-Density Self-Driven Electromagnetic Wheel: Comparison Of Different Tracks, Nathan Gr Gaul, Walerian Majewski

Exigence

The rotation of a permanent magnetic multipole wheel near a conducting non-magnetic plate creates a time-varying magnetic field that can produce by induction both repulsive levitation and propulsion forces. We constructed such an electrodynamic wheel using a motorized bicycle wheel with a radius of 12 inches and 36 one-inch cube Nd magnets attached to the rim of the wheel. The radial magnetic field on the outer rim of the wheel was maximized by arranging the magnets into a series of Halbach arrays which amplify the field along the rim. When a conductive metal “track” is immersed in this area of ...


Tracer Counterpermeation Analysis Of Diffusivity In Finite-Length Nanopores With And Without Single-File Dynamics, David Ackerman, James W. Evans 2017 Iowa State University

Tracer Counterpermeation Analysis Of Diffusivity In Finite-Length Nanopores With And Without Single-File Dynamics, David Ackerman, James W. Evans

Physics and Astronomy Publications

We perform a tracer counterpermeation (TCP) analysis for a stochastic model of diffusive transport through a narrow linear pore where passing of species within the pore is inhibited or even excluded (single-file diffusion). TCP involves differently labeled but otherwise identical particles from two decoupled infinite reservoirs adsorbing into opposite ends of the pore, and desorbing from either end. In addition to transient behavior, we assess steady-state concentration profiles, spatial correlations, particle number fluctuations, and diffusion fluxes through the pore. From the profiles and fluxes, we determine a generalized tracer diffusion coefficient Dtr(x), at various positions x within the pore ...


Design Of Radio-Frequency Arrays For Ultra-High Field Mri, Ian R O Connell 2017 The University of Western Ontario

Design Of Radio-Frequency Arrays For Ultra-High Field Mri, Ian R O Connell

Electronic Thesis and Dissertation Repository

Magnetic Resonance Imaging (MRI) is an indispensable, non-invasive diagnostic tool for the assessment of disease and function. As an investigational device, MRI has found routine use in both basic science research and medicine for both human and non-human subjects.

Due to the potential increase in spatial resolution, signal-to-noise ratio (SNR), and the ability to exploit novel tissue contrasts, the main magnetic field strength of human MRI scanners has steadily increased since inception. Beginning in the early 1980’s, 0.15 T human MRI scanners have steadily risen in main magnetic field strength with ultra-high field (UHF) 8 T MRI systems ...


Theoretical Approach To Electroresistance In Ferroelectric Tunnel Junctions, Sou-Chi Chang, Azad Naeemi, Dmitri E. Nikonov, Alexei Gruverman 2017 Georgia Institute of Technology

Theoretical Approach To Electroresistance In Ferroelectric Tunnel Junctions, Sou-Chi Chang, Azad Naeemi, Dmitri E. Nikonov, Alexei Gruverman

Alexei Gruverman Publications

In this paper, a theoretical approach comprising the nonequilibrium Green’s function method for electronic transport and the Landau-Khalatnikov equation for electric polarization dynamics is presented to describe polarization-dependent tunneling electroresistance (TER) in ferroelectric tunnel junctions. Using appropriate contact, interface, and ferroelectric parameters, the measured current-voltage characteristic curves in both inorganic (Co/BaTiO3/La0.67Sr0.33MnO3) and organic (Au/PVDF/W) ferroelectric tunnel junctions can be well described by the proposed approach. Furthermore, under this theoretical framework, the controversy of opposite TER signs observed experimentally by different groups in Co/BaTiO3/La0 ...


Anomalous Photovoltaic Effect In Organic-Inorganic Hybrid Perovskite Solar Cells, Yongbo Yuan, Tao Li, Qi Wang, Jie Xing, Alexei Gruverman, Jinsong Huang 2017 University of Nebraska - Lincoln

Anomalous Photovoltaic Effect In Organic-Inorganic Hybrid Perovskite Solar Cells, Yongbo Yuan, Tao Li, Qi Wang, Jie Xing, Alexei Gruverman, Jinsong Huang

Alexei Gruverman Publications

Organic-inorganic hybrid perovskites (OIHPs) have been demonstrated to be highly successful photovoltaic materials yielding very-high-efficiency solar cells. We report the room temperature observation of an anomalous photovoltaic (APV) effect in lateral structure OIHP devices manifested by the device’s open-circuit voltage (VOC) that is much larger than the bandgap of OIHPs. The persistent VOC is proportional to the electrode spacing, resembling that of ferroelectric photovoltaic devices. However, the APV effect in OIHP devices is not caused by ferroelectricity. The APV effect can be explained by the formation of tunneling junctions randomly dispersed in the polycrystalline films, which allows ...


Ch3Nh3Pbi3 Perovskites: Ferroelasticity Revealed, Evgheni Strelcov, Qingfeng Dong, Tao Li, Jungseok Chae, Yuchuan Shao, Yehao Deng, Alexei Gruverman, Jinsong Huang, Andrea Centrone 2017 National Institute of Standards and Technology

Ch3Nh3Pbi3 Perovskites: Ferroelasticity Revealed, Evgheni Strelcov, Qingfeng Dong, Tao Li, Jungseok Chae, Yuchuan Shao, Yehao Deng, Alexei Gruverman, Jinsong Huang, Andrea Centrone

Alexei Gruverman Publications

Ferroelectricity has been proposed as a plausible mechanism to explain the high photovoltaic conversion efficiency in organic-inorganic perovskites; however, convincing experimental evidence in support of this hypothesis is still missing. Identifying and distinguishing ferroelectricity from other properties, such as piezoelectricity, ferroelasticity, etc., is typically nontrivial because these phenomena can coexist in many materials. In this work, a combination of microscopic and nanoscale techniques provides solid evidence for the existence of ferroelastic domains in both CH3NH3PbI3 polycrystalline films and single crystals in the pristine state and under applied stress. Experiments show that the configuration of CH ...


Deformation And Adhesion Of Soft Composite Systems For Bio-Inspired Adhesives And Wrinkled Surface Fabrication, Michael Imburgia 2017 University of Massachusetts Amherst

Deformation And Adhesion Of Soft Composite Systems For Bio-Inspired Adhesives And Wrinkled Surface Fabrication, Michael Imburgia

Doctoral Dissertations May 2014 - current

The study of soft material deformation and adhesion has broad applicability to industries ranging from automobile tires to medical prosthetics and implants. When a mechanical load is imposed on a soft material system, a variety of issues can arise, including non-linear deformations at interfaces between soft and rigid components. The work presented in this dissertation embraces the occurrence of these non-linear deformations, leading to the design of functional systems that incorporate a soft elastomer layer with application to bio-inspired adhesives and wrinkled surface fabrication. Understanding the deformation of a soft elastomer layer and how the system loading and geometry influence ...


Mri-Based Susceptibility Mapping For In-Vivo Iron And Blood Oximetry Measurements, Hannah Erdevig 2017 University of Colorado, Boulder

Mri-Based Susceptibility Mapping For In-Vivo Iron And Blood Oximetry Measurements, Hannah Erdevig

Undergraduate Honors Theses

MRI is increasingly used in mapping tissue susceptibility to identify cerebral microbleeds associated with traumatic brain injury and pathological iron deposits associated with neurodegenerative diseases such as Parkinson's and Alzheimer's disease [1,2]. Accurate measurement is important for determining oxygen and iron content in blood vessels and tissue in the brain, which are in turn used for noninvasive clinical diagnosis and treatment assessments. Magnetic field distortions with a resolution of a few parts per billion can be measured using MRI phase maps. The field distortion map can then be inverted to obtain a quantitative susceptibility map. The primary ...


Investigation Of Three-Axis Accelerometer Calibration Techniques, Alec Archer 2017 University of Iowa

Investigation Of Three-Axis Accelerometer Calibration Techniques, Alec Archer

University of Iowa Honors Theses

Accelerometers are used in a variety of applications ranging from navigation systems to stand-alone tests. In each application, the accuracy of the accelerometer is crucial. There are various calibration techniques that range in precision, yet each apparatus devised to calibrate the accelerometer is quite complex. A calibration method of less complexity is desired to calibrate stand-alone accelerometers that require moderate accuracy. One stand-alone accelerometer, the X16-1D, was used to investigate calibration techniques. Six calibration techniques were investigated to determine an efficient method to calibrate a stand-alone accelerometer. Each method provided a different acceleration component that was modeled by theoretical equations ...


Proceedings Of The 2nd Resrb 2017 Conference, June 19-21, Wrocław, Poland, Wojciech M. Budzianowski 2016 Wroclaw University of Technology

Proceedings Of The 2nd Resrb 2017 Conference, June 19-21, Wrocław, Poland, Wojciech M. Budzianowski

Wojciech Budzianowski

No abstract provided.


Call For Abstracts - Resrb 2018, June 18-20, Brussels, Belgium, Wojciech M. Budzianowski 2016 Wroclaw University of Technology

Call For Abstracts - Resrb 2018, June 18-20, Brussels, Belgium, Wojciech M. Budzianowski

Wojciech Budzianowski

No abstract provided.


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