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- Elastic moduli (2)
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Articles 1 - 14 of 14
Full-Text Articles in Engineering Physics
). Size Dependency Of The Elastic Modulus Of Zno Nanowires: Surface Stress Effect, Guofeng Wang, Xiaodong Li
). Size Dependency Of The Elastic Modulus Of Zno Nanowires: Surface Stress Effect, Guofeng Wang, Xiaodong Li
Faculty Publications
Relation between the elastic modulus and the diameter (D) of ZnOnanowires was elucidated using a model with the calculated ZnOsurface stresses as input. We predict for ZnOnanowires due to surface stress effect: (1) when D>20nm, the elastic modulus would be lower than the bulk modulus and decrease with the decreasing diameter, (2) when 20nm>D>2nm, the nanowires with a longer length and a wurtzite crystal structure could be mechanically unstable, and (3) when D<2nm, the elastic modulus would be higher than that of the bulk value and increase with a decrease in nanowire diameter.
Nanoindentation Of The A And C Domains In A Tetragonal Batio3 Single Crystal, Young-Bae Park, Matthew J. Dicken, Zhi-Hui Xu, Xiaodong Li
Nanoindentation Of The A And C Domains In A Tetragonal Batio3 Single Crystal, Young-Bae Park, Matthew J. Dicken, Zhi-Hui Xu, Xiaodong Li
Faculty Publications
Nanoindentation in conjunction with piezoresponse force microscopy was used to study domain switching and to measure the mechanical properties of individual ferroelectric domains in a tetragonal BaTiO3 single crystal. It was found that nanoindentation has induced local domain switching; the a and c domains of BaTiO3 have different elastic moduli but similar hardness.Nanoindentationmodulus mapping on the a and c domains further confirmed such difference in elasticity. Finite element modeling was used to simulate the von Mises stress and plastic strain profiles of the indentations on both a and c domains, which introduces a much higher stress level than …
Parmela Based Simulations On Jefferson Lab Free Electron Laser Injector, Deepesh Kumar Koppunuru
Parmela Based Simulations On Jefferson Lab Free Electron Laser Injector, Deepesh Kumar Koppunuru
Electrical & Computer Engineering Theses & Dissertations
Free Electron Lasers (FELs) have many applications and are under continuing development to meet various needs and in areas from materials processing to life sciences research. This is because of its unique capability of generating high-average power, coherent, and wavelength tunable light by employing relativistic beam of un-bounded electrons. The main challenge in FEL development is the generation of a high intensity, high-quality electron beam in an injector. Further acceleration to relativistic energies is accomplished in a linear accelerator (LINAC) for producing laser light in a device known as wiggler. The Jefferson Lab FEL team intents to increase the injector …
The Fabrication And Characterization Of Granular Aluminium/Palladium Bilayer Microbolometers, Thomas E. Wilson
The Fabrication And Characterization Of Granular Aluminium/Palladium Bilayer Microbolometers, Thomas E. Wilson
Physics Faculty Research
Superconducting granular aluminium/palladium bilayer microbolometers with subnanosecond response can be easily fabricated using an all lift-off process with image-reversal lithography. The palladium capping layer allows for convenient and reproducible Ohmic contacts to be made to the device. We report their fabrication, resistance–current calibration, responsivity and response time. Finally, a deconvolution algorithm is used to improve the time resolution to approximately 1 ns while obtaining the incident photon and phonon fluxes in both direct photoexcitation and phonon heat pulse experiments.
Parallel Fast Multipole Method For Molecular Dynamics, Reid G. Ormseth
Parallel Fast Multipole Method For Molecular Dynamics, Reid G. Ormseth
Theses and Dissertations
We report on a parallel version of the Fast Multipole Method (FMM) implemented in the classical molecular dynamics code, NAMD (Not Another Molecular Dynamics program). This novel implementation of FMM aims to minimize interprocessor communication through the modification of the FMM grid to match the hybrid force and spatial decomposition scheme already present in NAMD. This new implementation has the benefit of replacing all-to-all communications broadcasts with direct communications between nearest neighbors. This results in a significant reduction in the amount of communication compared to earlier attempts to integrate FMM into common molecular dynamics programs. The early performance of FMM …
Investigation Of Magnetic Field Profile Effects In Hall Thrusters, Oren Kornberg
Investigation Of Magnetic Field Profile Effects In Hall Thrusters, Oren Kornberg
Master's Theses - Daytona Beach
The purpose of this study was to show the relationship of different magnetic field profiles to the acceleration region length of a Hall thruster. The general transport equations were simplified and solved using a one-dimensional analysis. Some of the model assumptions include quasineutrality, Maxwellian electrons, and negligible thruster wall effects. The solved equation kept magnetic field as an input to the model for the analysis. The magnetic field was altered by changing the shape through the thruster, while keeping the maximum point fixed, and by shifting the profile, while keeping the shape fixed. Results indicate a strong correlation between the …
Investigation Of Cdznte Crystal Defects Using Scanning Probe Microscopy, Goutam Koley, J. Liu, K. C. Mandal
Investigation Of Cdznte Crystal Defects Using Scanning Probe Microscopy, Goutam Koley, J. Liu, K. C. Mandal
Faculty Publications
No abstract provided.
Revisiting Hafemeister’S ‘Science And Society’ Tests, Robert J. Brecha, Rex L. Berney, Bruce A. Craver
Revisiting Hafemeister’S ‘Science And Society’ Tests, Robert J. Brecha, Rex L. Berney, Bruce A. Craver
Physics Faculty Publications
We revisit a series of papers on science and society issues by David Hafemeister in the 1970s and 1980s. The emphasis in the present work is on world oil production limits and some consequences of various possible scenarios for the near future. Some of the data and scenarios used by Hafemeister are updated for U.S. oil production in the past two decades and extended to an analysis of a peak in world oil production in the future. We discuss some simple scenarios for future energy use patterns and look at the consequence of these scenarios as world oil production begins …
Anisotropic Magnetoresistance In Colossal Magnetoresistive La1−XsrXMno3 Thin Films, Jeng-Bang Yau, X. Hong, A. Posadas, C. H. Ahn, W. Gao, E. Altman, Y. Bason, L. Klein, M. Sidorov, Z. Krivokapic
Anisotropic Magnetoresistance In Colossal Magnetoresistive La1−XsrXMno3 Thin Films, Jeng-Bang Yau, X. Hong, A. Posadas, C. H. Ahn, W. Gao, E. Altman, Y. Bason, L. Klein, M. Sidorov, Z. Krivokapic
Xia Hong Publications
We report on magnetic field and temperature-dependent measurements of the anisotropic magnetoresistance (AMR) in epitaxial La1−xSrxMnO3 (LSMO) thin films. While in 3d ferromagnetic alloys increasing the magnetization, either by reducing the temperature or increasing the magnetic field, increases the AMR, we find that in LSMO films the AMR dependence on magnetization displays nonmonotonic behavior which becomes particularly pronounced in lightly doped compounds. We believe that this behavior is related to the inhomogeneity exhibited by these materials.
Planar Hall Effect In Epitaxial Thin Films Of Magnetite, Y. Bason, L. Klein, H. Q. Wang, J. Hoffman, X. Hong, V. E. Henrich, C. H. Ahn
Planar Hall Effect In Epitaxial Thin Films Of Magnetite, Y. Bason, L. Klein, H. Q. Wang, J. Hoffman, X. Hong, V. E. Henrich, C. H. Ahn
Xia Hong Publications
We measured the planar Hall effect (PHE) of magnetite (Fe3O4) films between 150 and 350 K. The PHE was measured both with a constant magnetic field rotating in the plane of the sample and in a remanent state after applying a field in specific directions. The PHE amplitude decreases with temperature; however, it changes little between 300 and 350 K. The remanent PHE signal is as high as 10 V/A, larger than previously observed in manganite films. We also measured the PHE in the remanent state and found that its magnitude and stability make it a …
Magnetic Enhancement In Cobalt-Manganese Alloy Clusters, Shuangye Yin, Ramiro Moro, Xiaoshan Xu, Walter A. De Heer
Magnetic Enhancement In Cobalt-Manganese Alloy Clusters, Shuangye Yin, Ramiro Moro, Xiaoshan Xu, Walter A. De Heer
Xiaoshan Xu Papers
Magnetic moments of CoNMnM and CoNVM clusters (N ≤ 60; M ≤ N/3) are measured in molecular beams using the Stern-Gerlach deflection method. Surprisingly, the per atom average moments of CoNMnM clusters are found to increase with Mn concentration, in contrast to bulk CoMn. The enhancement with Mn doping is found to be independent of cluster size and composition in the size range studied. Meanwhile, CoNVM clusters show reduction of average moments with increasing V doping, consistent with what is expected in bulk CoV. The results are …
Rapid Structural Mapping Of Ternary Metallic Alloy Systems Using The Combinatorial Approach And Cluster Analysis, C. J. Long, Jason R. Hattrick-Simpers, M. Murakami, R. C. Srivastava, I. Takeuchi, V. L. Karen, X. Li
Rapid Structural Mapping Of Ternary Metallic Alloy Systems Using The Combinatorial Approach And Cluster Analysis, C. J. Long, Jason R. Hattrick-Simpers, M. Murakami, R. C. Srivastava, I. Takeuchi, V. L. Karen, X. Li
Faculty Publications
We are developing a procedure for the quick identification of structural phases in thin film composition spread experiments which map large fractions of compositional phase diagrams of ternary metallic alloy systems. An in-house scanning x-ray microdiffractometer is used to obtain x-ray spectra from 273 different compositions on a single composition spread library. A cluster analysissoftware is then used to sort the spectra into groups in order to rapidly discover the distribution of phases on the ternary diagram. The most representative pattern of each group is then compared to a database of known structures to identify known phases. Using this method, …
Low And Medium Β Superconducting Cavities And Accelerators, Jean R. Delayen
Low And Medium Β Superconducting Cavities And Accelerators, Jean R. Delayen
Physics Faculty Publications
No abstract provided.
A General Model Of Resistive Wall Instability In Linear Accelerators, Jean R. Delayen
A General Model Of Resistive Wall Instability In Linear Accelerators, Jean R. Delayen
Physics Faculty Publications
A general model for wakefield-generated instabilities in linear accelerators, originally developed for cumulative beam breakup [1], is applied to the resistive wall instability. The general solution for various bunch charge distributions and application to various accelerator configurations are presented.