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Development And Characterization Of Nb₃N/Al₂0₃ Superconducting Multilayers For Particle Accelerators, Chris Sundahl, Junki Makita, Paul B. Welander, Yi-Feng Su, Fumitake Kametani, Lin Xie, Huimin Zhang, Lian Li, Alex Gurevich, Chang-Beom Eom 2021 Old Dominion University

Development And Characterization Of Nb₃N/Al₂0₃ Superconducting Multilayers For Particle Accelerators, Chris Sundahl, Junki Makita, Paul B. Welander, Yi-Feng Su, Fumitake Kametani, Lin Xie, Huimin Zhang, Lian Li, Alex Gurevich, Chang-Beom Eom

Physics Faculty Publications

Superconducting radio-frequency (SRF) resonator cavities provide extremely high quality factors > 1010 at 1-2 GHz and 2 K in large linear accelerators of high-energy particles. The maximum accelerating field of SRF cavities is limited by penetration of vortices into the superconductor. Present state-of-the-art Nb cavities can withstand up to 50 MV/m accelerating gradients and magnetic fields of 200-240 mT which destroy the low-dissipative Meissner state. Achieving higher accelerating gradients requires superconductors with higher thermodynamic critical fields, of which Nb3Sn has emerged as a leading material for the next generation accelerators. To overcome the problem of low vortex ...


Treated Hfo2 Based Rram Devices With Ru, Tan, Tin As Top Electrode For In-Memory Computing Hardware, Yuvraj Dineshkumar Patel 2020 New Jersey Institute of Technology

Treated Hfo2 Based Rram Devices With Ru, Tan, Tin As Top Electrode For In-Memory Computing Hardware, Yuvraj Dineshkumar Patel

Theses

The scalability and power efficiency of the conventional CMOS technology is steadily coming to a halt due to increasing problems and challenges in fabrication technology. Many non-volatile memory devices have emerged recently to meet the scaling challenges. Memory devices such as RRAMs or ReRAM (Resistive Random-Access Memory) have proved to be a promising candidate for analog in memory computing applications related to inference and learning in artificial intelligence. A RRAM cell has a MIM (Metal insulator metal) structure that exhibits reversible resistive switching on application of positive or negative voltage. But detailed studies on the power consumption, repeatability and retention ...


Drawing Parallels In Art Science For Collaborative Learning: A Case Study, Karen Westland 2020 University of Dundee

Drawing Parallels In Art Science For Collaborative Learning: A Case Study, Karen Westland

The STEAM Journal

This research paper explores drawing as a tool to facilitate interdisciplinary practice. Outlined is the personal experience of PhD researcher [name removed] in their physics/craft research project, combined with thoughts and opinions from collaborators gathered through group discursive interviews. Interdisciplinary projects face interpersonal and conceptually ambiguous challenges which can be addressed through adopting drawing techniques for educational purposes. Findings highlight that drawing can assist across a breadth of applications as a learning tool for everyone, regardless of drawing ability, to improve the functionality of collaborative projects. Specifically, drawing combined with other communication techniques develops a performative communicative approach that ...


Numerical Simulation Of Nonlinear Vibrations Of Discrete Mass With Harmonic Force Perturbation, M. Yusupov, B. A. Akhmedov, Olga Karpova 2020 Chirchik State Pedagogical Institute of Tashkent region

Numerical Simulation Of Nonlinear Vibrations Of Discrete Mass With Harmonic Force Perturbation, M. Yusupov, B. A. Akhmedov, Olga Karpova

Acta of Turin Polytechnic University in Tashkent

The problem of vibration of a single-mass system under the force excitation of vibration associated with a fixed base by a weightless nonlinear viscoelastic spring is considered. To take into account the rheological properties of the spring material, the Boltzmann-Volterra principle was used. Mathematical models of the problem under consideration are obtained, which are described by integro-differential equations. A solution method based on the use of quadrature formulas has been developed and a computer program has been compiled on its basis, the results obtained are presented in the form of graphs. The influence of nonlinear and rheological properties of a ...


5. Programs And Algorithms, Zhiqu Lu, Likun Zhang, Lei Cao 2020 University of Mississippi

5. Programs And Algorithms, Zhiqu Lu, Likun Zhang, Lei Cao

Gulf Research Program Data Sets

This data set contains all codes for the study.


6. Supplemental Materials, Zhiqu Lu, Likun Zhang, Lei Cao 2020 University of Mississippi

6. Supplemental Materials, Zhiqu Lu, Likun Zhang, Lei Cao

Gulf Research Program Data Sets

This data set contains all conference presentations, manuscripts, technical reports, posters.


3. Localization, Zhiqu Lu, Likun Zhang, Lei Cao 2020 University of Mississippi

3. Localization, Zhiqu Lu, Likun Zhang, Lei Cao

Gulf Research Program Data Sets

This data set contains the results for oil leakage source localization.


2. Modeling, Zhiqu Lu, Likun Zhang, Lei Cao 2020 University of Mississippi

2. Modeling, Zhiqu Lu, Likun Zhang, Lei Cao

Gulf Research Program Data Sets

This data set contains the results for acoustic bubble modeling.


4. Metadata Files, Zhiqu Lu, Likun Zhang, Lei Cao 2020 University of Mississippi

4. Metadata Files, Zhiqu Lu, Likun Zhang, Lei Cao

Gulf Research Program Data Sets

This data set contains all ReadMe files for test data, modeling data, and localization data, as well as the corresponding codes.


1. Test Data, Zhiqu Lu, Likun Zhang, Lei Cao 2020 University of Mississippi

1. Test Data, Zhiqu Lu, Likun Zhang, Lei Cao

Gulf Research Program Data Sets

This data set contains recorded and processed bubble sounds under different conditions: a few bubbles vs. constant flow bubbles. Each condition is tested with nitrogen and with methane.


Low-Temperature Crystal Structure And Mean-Field Modeling Of Erxdy1−Xal2 Intermetallics, Yaroslav Mudryk, Bruno P. Alho, Paula O. Ribeiro, Vitalij K. Pecharsky 2020 Ames Laboratory

Low-Temperature Crystal Structure And Mean-Field Modeling Of Erxdy1−Xal2 Intermetallics, Yaroslav Mudryk, Bruno P. Alho, Paula O. Ribeiro, Vitalij K. Pecharsky

Ames Laboratory Accepted Manuscripts

Low-temperature crystal structure of the ErxDy1−xAl2 alloys with x = 0.45, 0.67, 0.90 was examined using temperature-dependent powder X-ray diffraction. The Er-rich sample, Er0.9Dy0.1Al2, exhibits a rhombohedral distortion associated with the magnetic ordering that occurs around 20 K. The rhombohedral distortion is suppressed in Er0.67Dy0.33Al2, while a weak low-temperature tetragonal distortion is observed in Er0.45Dy0.55Al2. The mean-field theory supports the correlation between the type of structural distortion and the variable easy ...


Improving Hydrid Pet/Mri Cardiovascular Imaging With Improved Hardware Design And Attenuation Correction Coefficient, Adam Helmy Farag 2020 The University of Western Ontario

Improving Hydrid Pet/Mri Cardiovascular Imaging With Improved Hardware Design And Attenuation Correction Coefficient, Adam Helmy Farag

Electronic Thesis and Dissertation Repository

According to the World Health Organization (WHO) report in 2019, cardiovascular diseases (CVD) cause 52% of all illness-related deaths globally and are considered to be the second most common cause of death in Canada. CVD is also estimated to cost the Canadian economy about $21.2 billion in direct and indirect costs. With these figures, it is vital to develop the most effective and accurate methods and tools to diagnose accurately CVD and their causes. One of the promising tools for accurate diagnostic and therapeutic of CVD is the integrated Positron Emission Tomography (PET) and Magnetic Resonance Imaging (MRI) PET ...


3-D Fabry–Pérot Cavities Sculpted On Fiber Tips Using A Multiphoton Polymerization Process, Jonathan W. Smith, Jeremiah C. Williams, Joseph S. Suelzer, Nicholas G. Usechak, Hengky Chandrahalim 2020 Air Force Institute of Technology

3-D Fabry–Pérot Cavities Sculpted On Fiber Tips Using A Multiphoton Polymerization Process, Jonathan W. Smith, Jeremiah C. Williams, Joseph S. Suelzer, Nicholas G. Usechak, Hengky Chandrahalim

Faculty Publications

This paper presents 3-D Fabry–Pérot (FP) cavities fabricated directly onto cleaved ends of low-loss optical fibers by a two-photon polymerization (2PP) process. This fabrication technique is quick, simple, and inexpensive compared to planar microfabrication processes, which enables rapid prototyping and the ability to adapt to new requirements. These devices also utilize true 3-D design freedom, facilitating the realization of microscale optical elements with challenging geometries. Three different device types were fabricated and evaluated: an unreleased single-cavity device, a released dual-cavity device, and a released hemispherical mirror dual-cavity device. Each iteration improved the quality of the FP cavity's reflection ...


Spectroscopic Diagnostics For Supersonic Air Microwave Discharges, James E. Caplinger 2020 Air Force Institute of Technology

Spectroscopic Diagnostics For Supersonic Air Microwave Discharges, James E. Caplinger

Theses and Dissertations

Optical Emission Spectroscopy (OES) is an increasingly relevant technique in plasma diagnostics due to its inherent non-invasive nature and simple application relative to other popular techniques. In this work, common OES techniques are combined with novel methods, developed here, in an effort to provide comprehensive OES techniques for stationary and supersonic air microwave discharges. To this end, a detailed collisional-radiative model for strong atomic oxygen lines has been developed and used to identify the importance of often overlooked mechanisms including cascade emission and metastable excitation. Using these results, a combined argon actinometry technique was developed which makes use of the ...


Cryogenic Spatial–Temporal Imaging Of Surface Photocarrier Dynamics In Mapbi3 Films At The Single Grain Level, Zhiyan Liu, Joong Mok Park, Liang Luo, Di Cheng, Chuankun Huang, Richard H. J. Kim, Chirag Vaswani, Zhaoning Song, Yanfa Yan, Yongxin Yao, Kai-Ming Ho, Jigang Wang 2020 Iowa State University and Ames Laboratory

Cryogenic Spatial–Temporal Imaging Of Surface Photocarrier Dynamics In Mapbi3 Films At The Single Grain Level, Zhiyan Liu, Joong Mok Park, Liang Luo, Di Cheng, Chuankun Huang, Richard H. J. Kim, Chirag Vaswani, Zhaoning Song, Yanfa Yan, Yongxin Yao, Kai-Ming Ho, Jigang Wang

Ames Laboratory Accepted Manuscripts

We use cryogenic spatial–temporal photoluminescence (PL) imaging measurements down to 10 K and with short-wavelength, 405 nm laser excitation to study surface charge generation, trapping, and recombination at single bright and dark grains as well as their boundaries in model methylammonium lead iodide (MAPbI3) polycrystalline thin films. These salient conditions are shown to be critical for identifying both the detrimental and cooperative roles of grain microstructures where the dark grains serve as the PL quenching center, while the grain boundaries are largely benign and may promote electron–hole separation.


Using Numerical Methods To Screen Magnetocaloric Materials In An Active Magnetic Regenerative Cycle, Huseyin Ucar, Durga Paudyal, Ozdal Boyraz 2020 California State Polytechnic University - Pomona

Using Numerical Methods To Screen Magnetocaloric Materials In An Active Magnetic Regenerative Cycle, Huseyin Ucar, Durga Paudyal, Ozdal Boyraz

Ames Laboratory Accepted Manuscripts

A 2-dimensional numerical model of a room temperature operating Active Magnetic Regenerator (AMR) that comprises of a regenerator, hot and cold heat exchangers, heat transfer fluid is developed. The regenerator is made of a magnetocaloric material (MCM) which heats up upon applying a magnetic field, H, and cools down when the field is removed; thus, making it the most essential part of an AMR. The model takes experimentally measured ∆Tad(H,T) and the Cp(H,T) data as input and provides quantitative performance metrics of the magnetic cooling system, such as ∆Tspan and the cooling load, as output. With ...


Dynamic Neuromechanical Sets For Locomotion, Aravind Sundararajan 2020 University Of Tennessee Knoxville

Dynamic Neuromechanical Sets For Locomotion, Aravind Sundararajan

Doctoral Dissertations

Most biological systems employ multiple redundant actuators, which is a complicated problem of controls and analysis. Unless assumptions about how the brain and body work together, and assumptions about how the body prioritizes tasks are applied, it is not possible to find the actuator controls. The purpose of this research is to develop computational tools for the analysis of arbitrary musculoskeletal models that employ redundant actuators. Instead of relying primarily on optimization frameworks and numerical methods or task prioritization schemes used typically in biomechanics to find a singular solution for actuator controls, tools for feasible sets analysis are instead developed ...


Local Structure And Dynamic Studies Of Mixed Ch4-Co2 Gas Hydrates Via Computational Simulation And Neutron Scattering, Bernadette Rita Cladek 2020 University of Tennessee, Knoxville

Local Structure And Dynamic Studies Of Mixed Ch4-Co2 Gas Hydrates Via Computational Simulation And Neutron Scattering, Bernadette Rita Cladek

Doctoral Dissertations

Permeated throughout the ocean floor and arctic permafrost, natural gas hydrates contain an estimated 3000 trillion cubic meters, over three times that of traditional shale deposits, of CH4 that is accessible for extraction. Gas hydrates are a crystal structure in which water molecules form a cage network, the host, through hydrogen bonds while trapping a guest molecule such as CH4 in the cavities. These compounds form naturally where the appropriate low temperature and high pressure conditions occur. A promising and tested method of methane recovery is through exchange with CO2, which energetically takes place of the methane ...


Reinvestigation Of The Intrinsic Magnetic Properties Of (Fe1-Xcox)(2)B Alloys And Crystallization Behavior Of Ribbons, Tej Nath Lamichhane, Olena Palasyuk, Vladimir P. Antropov, Ivan A. Zhuravlev, Kirill D. Belashchenko, Ikenna C. Nlebedim, Kevin W. Dennis, Anton Jesche, Matthew J. Kramer, Sergey L. Bud’ko, R. William McCallum, Paul C. Canfield, Valentin Taufour 2020 Iowa State University and Ames Laboratory

Reinvestigation Of The Intrinsic Magnetic Properties Of (Fe1-Xcox)(2)B Alloys And Crystallization Behavior Of Ribbons, Tej Nath Lamichhane, Olena Palasyuk, Vladimir P. Antropov, Ivan A. Zhuravlev, Kirill D. Belashchenko, Ikenna C. Nlebedim, Kevin W. Dennis, Anton Jesche, Matthew J. Kramer, Sergey L. Bud’Ko, R. William Mccallum, Paul C. Canfield, Valentin Taufour

Physics and Astronomy Publications

New determination of the magnetic anisotropy from single crystals of (Fe1-xCox)(2)B alloys are presented. The anomalous temperature dependence of the anisotropy constant is discussed using the standard Callen-Callen theory, which is shown to be insufficient to explain the experimental results. A more material specific study using first-principles calculations with disordered moments approach gives a much more consistent interpretation of the experimental data. Since the intrinsic properties of the alloys with x = 0.3 - 0.35 are promising for permanent magnets applications, initial investigation of the extrinsic properties are described, in particular the crystallization of melt spun ribbons with ...


Finite-Strain Scale-Free Phase-Field Approach To Multivariant Martensitic Phase Transformations With Stress-Dependent Effective Thresholds, Hamed Babaei, Valery I. Levitas 2020 Iowa State University

Finite-Strain Scale-Free Phase-Field Approach To Multivariant Martensitic Phase Transformations With Stress-Dependent Effective Thresholds, Hamed Babaei, Valery I. Levitas

Aerospace Engineering Publications

A scale-free phase-field model for martensitic phase transformations (PTs) at finite strains is developed as an essential generalization of small-strain models in Levitas et al. (2004) and Idesman et al. (2005). The theory includes finite elastic and transformational strains and rotations as well as anisotropic and different elastic properties of phases. The gradient energy term is excluded, and the model is applicable for any scale greater than 100 nm. The model tracks finite-width interfaces between austenite and the mixture of martensitic variants only; volume fractions of martensitic variants are the internal variables rather than order parameters. The concept of the ...


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