Kemar Hats Head Orientation Directivity,
2022
Brigham Young University
Kemar Hats Head Orientation Directivity, Samuel D. Bellows, Timothy W. Leishman
Directivity
This directivity data set for a KEMAR head head-and-torso simulator (HATS) includes head orientations in 14 directions in 5° steps starting from 0° to 40° and then in 10° steps from 40° to 90°. The full spherical measurements followed at an a = 0.97 m radius with the mouth aperture at the spherical center. The sampling density and distribution followed the AES 5° dual-equiangular sampling standard, omitting the south pole (θ = 180°). Thus, each spherical directivity assessment included 36 polar-angle θ samples and 72 azimuthal-angle ϕ samples. The presented data include 22 1/3-octave bands, ranging from 80 Hz …
Flexible Dye-Sensitized Solar Cells Assisted With Lead-Free Perovskite Halide,
2022
Marshall University
Flexible Dye-Sensitized Solar Cells Assisted With Lead-Free Perovskite Halide, Judy Fan
Physics Faculty Research
Dye-sensitized solar cells (DSSCs) have shown promising alternative to Si-based counterparts due to low-cost, abundant raw materials, and non-vacuum processing. Here, we report a solution-based process to create flexible DSSCs on aluminum foils. Mesoporous TiO2 electrode was directly deposited on Al foil through spin casting. After post-thermal annealing, the resultant samples render optical smooth, crack-free, and large nanocrystalline thin films. The as-prepared double-layer porous TiO2 thin film was incorporated with a porphyrin dye followed by a perovskite halide salt Cs2SnI6, as the hole transport material, replacing liquid electrolyte. A transparent conducting plastic sheet was …
Development Of Advanced Machine Learning Models For Analysis Of Plutonium Surrogate Optical Emission Spectra,
2022
Air Force Institute of Technology
Development Of Advanced Machine Learning Models For Analysis Of Plutonium Surrogate Optical Emission Spectra, Ashwin P. Rao, Phillip R. Jenkins, John D. Auxier Ii, Michael B. Shattan, Anil Patnaik
Faculty Publications
This work investigates and applies machine learning paradigms seldom seen in analytical spectroscopy for quantification of gallium in cerium matrices via processing of laser-plasma spectra. Ensemble regressions, support vector machine regressions, Gaussian kernel regressions, and artificial neural network techniques are trained and tested on cerium-gallium pellet spectra. A thorough hyperparameter optimization experiment is conducted initially to determine the best design features for each model. The optimized models are evaluated for sensitivity and precision using the limit of detection (LoD) and root mean-squared error of prediction (RMSEP) metrics, respectively. Gaussian kernel regression yields the superlative predictive model with an RMSEP of …
A Modulated Structure Derived From The Xa-Type
Mn2Rusn Heusler Compound,
2022
University of Nebraska-Lincoln
A Modulated Structure Derived From The Xa-Type Mn2Rusn Heusler Compound, Xingzhong Li, Wen-Yong Zhang, Ralph Skomski, David J. Sellmyer
Nebraska Center for Materials and Nanoscience: Faculty Publications
A modulated structure derived from the inverse Heusler phase (the XA-type and the disordered variant L21B-type) has been observed in rapidly quenched Mn2RuSn ribbons. The powder X-ray diffraction pattern of the quenched ribbons can be indexed as an L21B-type structure. Electron diffraction patterns of the new structure mostly resemble those of the XA-type (and the disordered variant L21B-type) structure and additional reflections with denser spacing indicate a long periodicity. Orthogonal domains of the modulated structure were revealed by a selected-area electron diffraction pattern and the corresponding dark-field transmission electron microscopy images. The structure was …
Localization Effects And Anomalous Hall Conductivity In A Disordered 3d Ferromagnet,
2022
University of Northern Iowa
Localization Effects And Anomalous Hall Conductivity In A Disordered 3d Ferromagnet, Paul M. Shand, Y. Moua, G. Baker, Shah R. Valloppilly, Pavel V. Lukashev, Parashu Kharel
Nebraska Center for Materials and Nanoscience: Faculty Publications
We have prepared the Heusler alloy CoFeV0.5Mn0.5Si in bulk form via arc melting. CoFeV0.5Mn0.5Si is ferromagnetic with a Curie temperature of 657 K. The longitudinal resistivity exhibits a minimum at 150 K, which is attributable to competition between quantum interference corrections at low temperatures and inelastic scattering at higher temperatures. The magnetoresistance (MR) is positive and nearly linear at low temperatures and becomes negative at temperatures close to room temperature. The positive MR in the quantum correction regime is evidence of the presence of the enhanced electron interaction as a contributor to …
A Monolithic 3d Printed Axisymmetric Co-Flow Single And Compound Emulsion Generator,
2022
University of Illinois at Chicago
A Monolithic 3d Printed Axisymmetric Co-Flow Single And Compound Emulsion Generator, Amirreza Ghaznavi, Yang Lin, Mark Douvidzon, Adam Szmelter, Alannah Rodrigues, Malik Blackman, David Eddington, Tal Carmon, Lev Deych, Lan Yang, Jie Xu
Publications and Research
We report a microfluidic droplet generator which can produce single and compound droplets using a 3D axisymmetric co-flow structure. The design considered for the fabrication of the device integrated a user-friendly and cost-effective 3D printing process. To verify the performance of the device, single and compound emulsions of deionized water and mineral oil were generated and their features such as size, generation frequency, and emulsion structures were successfully characterized. In addition, the generation of bio emulsions such as alginate and collagen aqueous droplets in mineral oil was demonstrated in this study. Overall, the monolithic 3D printed axisymmetric droplet generator could …
Enhanced Study Of Complex Systems By Unveiling Hidden Symmetries With Dynamical Visibility,
2022
Eastern Washington University
Enhanced Study Of Complex Systems By Unveiling Hidden Symmetries With Dynamical Visibility, Nhat Vu Minh Nguyen
2022 Symposium
One of the great challenges in complex and chaotic dynamics is to reveal its deterministic structures. These temporal dynamical structures are sometimes a consequence of hidden symmetries. Detecting and understanding them can allow the study of complex systems even without knowing the full underlying mathematical description of the system. Here we introduce a new technique, called Dynamical Visibility, that quantifies temporal correlations of the dynamics based upon some symmetry conditions. This visibility measures the departure of the dynamics from internal symmetries. We apply this technique to well-known chaotic systems, such as the logistic map and the circle map, as well …
Studying The Conditions For Magnetic Reconnection In Solar Flares With And Without Precursor Flares,
2022
Air Force Institute of Technology
Studying The Conditions For Magnetic Reconnection In Solar Flares With And Without Precursor Flares, Seth H. Garland, Daniel J. Emmons, Robert D. Loper
Faculty Publications
Forecasting of solar flares remains a challenge due to the limited understanding of the triggering mechanisms associated with magnetic reconnection, the primary physical phenomenon connected to these events. Studies have indicated that changes to the photospheric magnetic fields associated with magnetic reconnection – particularly in relation to the field helicity – occur during solar flare events. This study utilized data from the Solar Dynamics Observatory (SDO) Helioseismic and Magnetic Imager (HMI) and SpaceWeather HMI Active Region Patches (SHARPs) to analyze full vector-field component data of the photospheric magnetic field during solar flare events within a near decade long HMI dataset. …
What Happens When Transition Metal Trichalcogenides Are Interfaced With Gold?,
2022
University of Nebraska–Lincoln
What Happens When Transition Metal Trichalcogenides Are Interfaced With Gold?, Archit Dhingra, Dmitri E. Nikonov, Alexey Lipatov, Alexander Sinitskii, Peter Dowben
Peter Dowben Publications
Transition metal trichalcogenides (TMTs) are two-dimensional (2D) systems with quasi-one-dimensional (quasi-1D) chains. These 2D materials are less susceptible to undesirable edge defects, which enhances their promise for low-dimensional optical and electronic device applications. However, so far, the performance of 2D devices based on TMTs has been hampered by contact-related issues. Therefore, in this review, a diligent effort has been made to both elucidate and summarize the interfacial interactions between gold and various TMTs, namely, In4Se3, TiS3, ZrS3, HfS3, and HfSe3. X-ray photoemission spectroscopy data, supported by the results …
High Resolution Diagnostic Tools For Superconducting Radio Frequency Cavities,
2022
Old Dominion University
High Resolution Diagnostic Tools For Superconducting Radio Frequency Cavities, I. Parajuli, G. Ciovati, J. R. Delayen
Physics Faculty Publications
Superconducting radio-frequency (SRF) cavities are one of the fundamental building blocks of modern particle accelerators. To achieve the highest quality factors (1010–1011), SRF cavities are operated at liquid helium temperatures. Magnetic flux trapped on the surface of SRF cavities during cool-down below the critical temperature is one of the leading sources of residual RF losses. Instruments capable of detecting the distribution of trapped flux on the cavity surface are in high demand in order to better understand its relation to the cavity material, surface treatments and environmental conditions. We have designed, developed, and commissioned two high-resolution …
Theoretical Investigation On Optical Properties Of 2d Materials And Mechanical Properties Of Polymer Composites At Molecular Level,
2022
Michigan Technological University
Theoretical Investigation On Optical Properties Of 2d Materials And Mechanical Properties Of Polymer Composites At Molecular Level, Geeta Sachdeva
Dissertations, Master's Theses and Master's Reports
The field of two-dimensional (2D) layered materials provides a new platform for studying diverse physical phenomena that are scientifically interesting and relevant for technological applications. Theoretical predictions from atomically resolved computational simulations of 2D materials play a pivotal role in designing and advancing these developments. The focus of this thesis is 2D materials especially graphene and BN studied using density functional theory (DFT) and molecular dynamics (MD) simulations. In the first half of the thesis, the electronic structure and optical properties are discussed for graphene, antimonene, and borophene. It is found that the absorbance in (atomically flat) multilayer antimonene (group …
Preliminary Results From Magnetic Field Scanning System For A Single-Cell Niobium Cavity,
2022
Old Dominion University
Preliminary Results From Magnetic Field Scanning System For A Single-Cell Niobium Cavity, Ishwari Prasad Parajuli, Gianluigi Ciovati, Jean R. Delayen, Alex V. Gurevich
Physics Faculty Publications
One of the building blocks of modern particle accelerators is superconducting radiofrequency (SRF) cavities. Niobium is the material of choice to build such cavities, which operate at liquid helium temperature (2 - 4 K) and have some of the highest quality factors found in Nature. There are several sources of residual losses, one of them is trapped magnetic flux, which limits the quality factor in SRF cavities. The flux trapping mechanism depends on different niobium surface preparations and cool-down conditions. Suitable diagnostic tools are not yet available to study the effects of such conditions on magnetic flux trapping. A magnetic …
Modeling, Fabrication, And Characterization Of Rf-Based Passive Wireless Sensors Composed Of Refractory Semiconducting Ceramics For High Temperature Applications,
2022
West Virginia University
Modeling, Fabrication, And Characterization Of Rf-Based Passive Wireless Sensors Composed Of Refractory Semiconducting Ceramics For High Temperature Applications, Kavin Sivaneri Varadharajan Idhaiam
Graduate Theses, Dissertations, and Problem Reports
Real-time health monitoring of high temperature systems (>500oC) in harsh environments is necessary to prevent catastrophic events caused by structural failures, varying pressure, and chemical reactions. Conventional solid-state temperature sensors such as resistance temperature detectors (RTDs) and thermocouples are restricted by their operating environments, sensor dimensions and often require external power sources for their operation. The current work presents the research and development of RF-based passive wireless sensing technology targeting high temperatures and harsh environmental conditions. Passive wireless devices are generally classified as near-field and far-field devices based on the interrogation distance. Near-field sensors are placed at …
Deep Learning Based Superconducting Radio-Frequency Cavity Fault Classification At Jefferson Laboratory,
2022
Old Dominion University
Deep Learning Based Superconducting Radio-Frequency Cavity Fault Classification At Jefferson Laboratory, Lasitha Vidyaratne, Adam Carpenter, Tom Powers, Chris Tennant, Khan M. Iftekharuddin, Md. Monibor Rahman, Anna S. Shabalina
Electrical & Computer Engineering Faculty Publications
This work investigates the efficacy of deep learning (DL) for classifying C100 superconducting radio-frequency (SRF) cavity faults in the Continuous Electron Beam Accelerator Facility (CEBAF) at Jefferson Lab. CEBAF is a large, high-power continuous wave recirculating linac that utilizes 418 SRF cavities to accelerate electrons up to 12 GeV. Recent upgrades to CEBAF include installation of 11 new cryomodules (88 cavities) equipped with a low-level RF system that records RF time-series data from each cavity at the onset of an RF failure. Typically, subject matter experts (SME) analyze this data to determine the fault type and identify the cavity of …
Beamline For E-Beam Processing At Uitf,
2022
Old Dominion University
Beamline For E-Beam Processing At Uitf, G. Ciovati, C. Bott, S. Gregory, F. Hannon, Xi Li, M. Mccaughan, R. Pearce, M. Poelker, H. Vennekate
Electrical & Computer Engineering Faculty Publications
No abstract provided.
Real-Time Cavity Fault Prediction In Cebaf Using Deep Learning,
2022
Old Dominion University
Real-Time Cavity Fault Prediction In Cebaf Using Deep Learning, Md. M. Rahman, K. Iftekharuddin, A. Carptenter, T. Mcguckin, C. Tennant, L. Vidyaratne, Sandra Biedron (Ed.), Evgenya Simakov (Ed.), Stephen Milton (Ed.), Petr M. Anisimov (Ed.), Volker R.W. Schaa (Ed.)
Electrical & Computer Engineering Faculty Publications
Data-driven prediction of future faults is a major research area for many industrial applications. In this work, we present a new procedure of real-time fault prediction for superconducting radio-frequency (SRF) cavities at the Continuous Electron Beam Accelerator Facility (CEBAF) using deep learning. CEBAF has been afflicted by frequent downtime caused by SRF cavity faults. We perform fault prediction using pre-fault RF signals from C100-type cryomodules. Using the pre-fault signal information, the new algorithm predicts the type of cavity fault before the actual onset. The early prediction may enable potential mitigation strategies to prevent the fault. In our work, we apply …
Nb₃Sn Coating Of A 2.6 Ghz Srf Cavity By Sputter Deposition Technique,
2022
Old Dominion University
Nb₃Sn Coating Of A 2.6 Ghz Srf Cavity By Sputter Deposition Technique, M. S. Shakel, Wei Cao, H. Elsayed-Ali, G. V. Eremeev, U. Pudasaini, A. M. Valente-Feliciano
Electrical & Computer Engineering Faculty Publications
Nb₃Sn is of interest as a coating for SRF cavities due to its higher transition temperature Tc ~18.3 K and superheating field Hsh ~400 mT, both are twice that of Nb. Nb₃Sn coated cavities can achieve high-quality factors at 4 K and can replace the bulk Nb cavities operated at 2 K. A cylindrical magnetron sputtering system was built, commissioned, and used to deposit Nb₃Sn on the inner surface of a 2.6 GHz single-cell Nb cavity. With two identical cylindrical magnetrons, this system can coat a cavity with high symmetry and uniform thickness. Using Nb-Sn multilayer sequential sputtering followed by …
Nonlinear Meissner Effect In Nb3Sn Coplanar Resonators,
2022
Old Dominion University
Nonlinear Meissner Effect In Nb3Sn Coplanar Resonators, Junki Makita, C. Sundahl, Gianluigi Ciovati, C. B. Eom, Alex Gurevich
Physics Faculty Publications
We investigated the nonlinear Meissner effect (NLME) in Nb3Sn thin-film coplanar resonators by measuring the resonance frequency as a function of a parallel magnetic field at different temperatures. We used low rf power probing in films thinner than the London penetration depth λ(B) to significantly increase the field onset of vortex penetration and measure the NLME under equilibrium conditions. Contrary to the conventional quadratic increase of λ(B) with B expected in s-wave superconductors, we observed a nearly linear increase of the penetration depth with B. We concluded that this behavior of λ(B) is due to weak linked grain …
Cooling Performance In A Dual Energy Storage Ring Cooler,
2022
Old Dominion University
Cooling Performance In A Dual Energy Storage Ring Cooler, B. Dhital, Y. S. Derbenev, D. Douglas, G. A. Krafft, H. Zhang, F. Lin, V. S. Morozov, Y. Zhang
Physics Faculty Publications
The longitudinal and transverse emittance growth in hadron beams due to intra-beam scattering (IBS) and other heating sources deteriorate the luminosity in a collider. Hence, a strong hadron beam cooling is required to reduce and preserve the emittance. The cooling of high energy hadron beam is challenging. We propose a dual energy storage ring-based electron cooler that uses an electron beam to extract heat away from hadron beam in the cooler ring while the electron beam is cooled by synchrotron radiation damping in the high energy damping ring. In this paper, we present a design of a dual energy storage …
Cebaf Injector Model For KL Beam Conditions,
2022
Old Dominion University
Cebaf Injector Model For KL Beam Conditions, Sunil Pokharel, Geoffrey A. Krafft, A. S. Hofler, R. Kazimi, M. Bruker, J. Grames, S. Zhang
Physics Faculty Publications
The Jefferson Lab KL experiment will run at the Continuous Electron Beam Accelerator Facility with a much lower bunch repetition rate (7.80 or 15.59 MHz) than nominally used (249.5 or 499 MHz). While the proposed average current of 2.5 - 5.0 µA is relatively low compared to the maximum CEBAF current of approximately 180 µA, the corresponding bunch charge is atypically high for CEBAF injector operation. In this work, we investigated the evolution and transmission of low-rep-rate, high-bunch-charge (0.32 to 0.64 pC) beams through the CEBAF injector. Using the commercial software General Particle Tracer, we have simulated and analyzed the …
