Alison Flatau | University of Maryland (original) (raw)
Papers by Alison Flatau
27th Aerospace Sciences Meeting, 1989
AIAA Scitech 2021 Forum, 2021
AIAA Scitech 2021 Forum, 2021
Volume 6: Ceramics; Controls, Diagnostics, and Instrumentation; Education; Manufacturing Materials and Metallurgy, 2019
Sand particulate ingestion into modern gas turbine engines for fixed wing and vertical lift aircr... more Sand particulate ingestion into modern gas turbine engines for fixed wing and vertical lift aircraft is a significant challenge for both military and civilian missions. ARL as part of a DoD funded Laboratory University Collaborative Initiative (LUCI) and Vannevar Bush Fellowship at UCSD are investigating the governing parameters that primarily influences the CMAS adhesion kinetics and infiltration on the standard Yttria Stabilized Zirconia (YSZ) as part of metallic single crystal Nickel superalloys TBC and SiC/SiC CMC T/EBCs. Current research shows various parameters including CMAS viscosity, porosity, adhesion strength, contact angle (wettability factor), geological factors affecting sand formation, coating and structural substrate roughness and surface temperature, internal flow Reynolds number, temperature, pressure, Mach number, boundary layer and bleed air, coating process (columnar vs splat morphology), tortuosity factor et al affects the CMAS adhesion and infiltration. This p...
Magnetic Nano- and Microwires, 2020
Abstract Magnetic nanowires, fabricated by template-assisted electrochemical deposition, have bee... more Abstract Magnetic nanowires, fabricated by template-assisted electrochemical deposition, have been proposed for a wide range of applications, including Fe-Ga alloy magnetostrictive nanosensors and actuators, Co/Cu multilayered CPP-GMR structures, cell labels and identification, MRI contrast agents, and nanowarming agents. The desired magnetic properties for each of these applications are described in this chapter. In addition, a simple and cost-effective double imprinting technique is described that yields long-range ordered anodic aluminum oxide templates for 3-D magnetic memory.
Applied Mechanics Reviews, 2021
This review article examines the last decade of studies investigating solid, molten, and liquid p... more This review article examines the last decade of studies investigating solid, molten, and liquid particle interactions with one another and with walls in heterogeneous multiphase flows. Such flows are experienced in state-of-the-art and future-concept gas turbine engines, where particles from the environment, including volcanic ash, runway debris, dust clouds, and sand, are transported by a fluid carrier phase and undergo high-speed collisions with high-temperature engine components. Sand or volcanic ash ingestion in gas turbine engines is known to lead to power-loss and/or complete engine failure. The particle-wall interactions that occur in high-temperature sections of an engine involve physics and intrinsic conditions that are sufficiently complex that they result in highly disparate and transient outcomes. These particles, which often times are made up of glassy constituents called calcium–magnesium–alumino–silicate (CMAS), are susceptible to phase change at combustor temperature...
Journal of Materials Research, 2020
IEEE Sensors Journal, 2017
IEEE Transactions on Magnetics, 2017
Proceedings of Spie the International Society For Optical Engineering, May 1, 2005
Smart Materials and Structures, 2014
The Journal of the Acoustical Society of America, 2009
A novel cilia design is introduced that incorporates a newly discovered magnetostrictive family o... more A novel cilia design is introduced that incorporates a newly discovered magnetostrictive family of Fe–Ga alloys, also called Galfenol, into self‐assembled, vertical nanopores to fabricate nanocantilevers. The mechanical response of the cilia to stimuli can be detected without direct contact by detecting their magnetic output via giant magnetoresistive sensors, similar to hard drive heads which can also be grown in nanoarrays. The electrochemistry of alloys involving non‐ideal metals is very complex, so finite element modeling was used to simulate growth parameters and successful growth was achieved. A variety of nanowire geometries were produced, including segmented Galfenol with alternating nonmagnetic material to overcome the shape anisotropy of the nanowires. In addition, the mechanical properties of this new material were measured to determine the effects of nanostructuring. Finally, the nanowires were actuated using an external field to show their potential actuators as well as sensors. [Work support...
Journal of Propulsion and Power, 2003
Results are presented from a cold-flow investigation of acoustic responses driven by flow through... more Results are presented from a cold-flow investigation of acoustic responses driven by flow through two annular baffles in a cylindrical cavity, having (approximately) closed-closed end conditions. The interaction of the flow with cavity acoustic resonances was examined for different baffle radii, positions, spacings, and stiffness. Nominal vortex shedding frequencies were found to depend on baffle spacing and radii (flow velocity), with little sensitivity to baffle stiffness. Vortex shedding lock-in frequencies were very sensitive to acoustic pressures and/or acoustic particle velocities acting on the flow at both the upstream and downstream baffles. Vortex shedding lock-in occurred in conjunction with acoustic standing waves formed between the baffles and ends of the test chamber such that either acoustic pressure maxima (closed conditions) occurred at the upstream baffle or acoustic velocity maxima (pressure release or open conditions) occurred at the downstream baffle. High acoustic pressure at the upstream baffle appeared to enhance the strength of the shed vortices, and low acoustic pressure (high acoustic particle velocity) at the downstream baffle appeared to enhance the strength of the acoustic field radiated on vortex impingement. For most of the two baffle geometries, baffle-to-nozzle acoustic modes were the dominant mechanism responsible for lock-in and strong reinforcement of vortex shedding driven acoustic excitation.
Journal of Magnetism and Magnetic Materials, 2007
The texture development of {1 0 0} and {1 1 0} preferred orientations in Fe Ga sheets annealed un... more The texture development of {1 0 0} and {1 1 0} preferred orientations in Fe Ga sheets annealed under a sulfur atmosphere and the surface segregation of sulfur were investigated. The two fitted S 2p3/2 peak positions at 161.46 and 163.06 eV by XPS represent the presence of iron sulfide on sheet surfaces. The selective growth of (1 0 0) and (1 1 0) grains was achieved through controlling the segregation of sulfur by annealing in quartz ampoules with varied sulfur content and varied annealing times at 1200 °C.
![Research paper thumbnail of Erratum: “Energy-based quasi-static modeling of the actuation and sensing behavior of single-crystal iron-gallium alloys” [J. Appl. Phys. 103, 014901 (2008)]](https://attachments.academia-assets.com/93287598/thumbnails/1.jpg)
](Journal of Applied Physics, 2008
Journal of Applied Physics, 2012
In this work, magnetization reversal mechanisms in various 35 nm diameter Fe80Ga20/Cu multilayere... more In this work, magnetization reversal mechanisms in various 35 nm diameter Fe80Ga20/Cu multilayered nanowire arrays were studied by a vibrating sample magnetometer (VSM) equipped with vector coils, making it possible to monitor both x- and y-components of the sample moment during reversal. When reversal fields were applied in the low angular range (0 – 60°), all nanowire structures, irrespective of Fe80Ga20 or Cu aspect ratios, experienced reversal by nucleation and propagation of a vortex domain wall. However, when fields were applied in the high angular range of 60–90°, reversal occurred by coherent rotation. Using vector-VSM, it was further shown that in structures with pancake-like Fe80Ga20 segments, the extent to which moments in adjacent segments rotate cooperatively decreased as the Cu thickness increased.
27th Aerospace Sciences Meeting, 1989
AIAA Scitech 2021 Forum, 2021
AIAA Scitech 2021 Forum, 2021
Volume 6: Ceramics; Controls, Diagnostics, and Instrumentation; Education; Manufacturing Materials and Metallurgy, 2019
Sand particulate ingestion into modern gas turbine engines for fixed wing and vertical lift aircr... more Sand particulate ingestion into modern gas turbine engines for fixed wing and vertical lift aircraft is a significant challenge for both military and civilian missions. ARL as part of a DoD funded Laboratory University Collaborative Initiative (LUCI) and Vannevar Bush Fellowship at UCSD are investigating the governing parameters that primarily influences the CMAS adhesion kinetics and infiltration on the standard Yttria Stabilized Zirconia (YSZ) as part of metallic single crystal Nickel superalloys TBC and SiC/SiC CMC T/EBCs. Current research shows various parameters including CMAS viscosity, porosity, adhesion strength, contact angle (wettability factor), geological factors affecting sand formation, coating and structural substrate roughness and surface temperature, internal flow Reynolds number, temperature, pressure, Mach number, boundary layer and bleed air, coating process (columnar vs splat morphology), tortuosity factor et al affects the CMAS adhesion and infiltration. This p...
Magnetic Nano- and Microwires, 2020
Abstract Magnetic nanowires, fabricated by template-assisted electrochemical deposition, have bee... more Abstract Magnetic nanowires, fabricated by template-assisted electrochemical deposition, have been proposed for a wide range of applications, including Fe-Ga alloy magnetostrictive nanosensors and actuators, Co/Cu multilayered CPP-GMR structures, cell labels and identification, MRI contrast agents, and nanowarming agents. The desired magnetic properties for each of these applications are described in this chapter. In addition, a simple and cost-effective double imprinting technique is described that yields long-range ordered anodic aluminum oxide templates for 3-D magnetic memory.
Applied Mechanics Reviews, 2021
This review article examines the last decade of studies investigating solid, molten, and liquid p... more This review article examines the last decade of studies investigating solid, molten, and liquid particle interactions with one another and with walls in heterogeneous multiphase flows. Such flows are experienced in state-of-the-art and future-concept gas turbine engines, where particles from the environment, including volcanic ash, runway debris, dust clouds, and sand, are transported by a fluid carrier phase and undergo high-speed collisions with high-temperature engine components. Sand or volcanic ash ingestion in gas turbine engines is known to lead to power-loss and/or complete engine failure. The particle-wall interactions that occur in high-temperature sections of an engine involve physics and intrinsic conditions that are sufficiently complex that they result in highly disparate and transient outcomes. These particles, which often times are made up of glassy constituents called calcium–magnesium–alumino–silicate (CMAS), are susceptible to phase change at combustor temperature...
Journal of Materials Research, 2020
IEEE Sensors Journal, 2017
IEEE Transactions on Magnetics, 2017
Proceedings of Spie the International Society For Optical Engineering, May 1, 2005
Smart Materials and Structures, 2014
The Journal of the Acoustical Society of America, 2009
A novel cilia design is introduced that incorporates a newly discovered magnetostrictive family o... more A novel cilia design is introduced that incorporates a newly discovered magnetostrictive family of Fe–Ga alloys, also called Galfenol, into self‐assembled, vertical nanopores to fabricate nanocantilevers. The mechanical response of the cilia to stimuli can be detected without direct contact by detecting their magnetic output via giant magnetoresistive sensors, similar to hard drive heads which can also be grown in nanoarrays. The electrochemistry of alloys involving non‐ideal metals is very complex, so finite element modeling was used to simulate growth parameters and successful growth was achieved. A variety of nanowire geometries were produced, including segmented Galfenol with alternating nonmagnetic material to overcome the shape anisotropy of the nanowires. In addition, the mechanical properties of this new material were measured to determine the effects of nanostructuring. Finally, the nanowires were actuated using an external field to show their potential actuators as well as sensors. [Work support...
Journal of Propulsion and Power, 2003
Results are presented from a cold-flow investigation of acoustic responses driven by flow through... more Results are presented from a cold-flow investigation of acoustic responses driven by flow through two annular baffles in a cylindrical cavity, having (approximately) closed-closed end conditions. The interaction of the flow with cavity acoustic resonances was examined for different baffle radii, positions, spacings, and stiffness. Nominal vortex shedding frequencies were found to depend on baffle spacing and radii (flow velocity), with little sensitivity to baffle stiffness. Vortex shedding lock-in frequencies were very sensitive to acoustic pressures and/or acoustic particle velocities acting on the flow at both the upstream and downstream baffles. Vortex shedding lock-in occurred in conjunction with acoustic standing waves formed between the baffles and ends of the test chamber such that either acoustic pressure maxima (closed conditions) occurred at the upstream baffle or acoustic velocity maxima (pressure release or open conditions) occurred at the downstream baffle. High acoustic pressure at the upstream baffle appeared to enhance the strength of the shed vortices, and low acoustic pressure (high acoustic particle velocity) at the downstream baffle appeared to enhance the strength of the acoustic field radiated on vortex impingement. For most of the two baffle geometries, baffle-to-nozzle acoustic modes were the dominant mechanism responsible for lock-in and strong reinforcement of vortex shedding driven acoustic excitation.
Journal of Magnetism and Magnetic Materials, 2007
The texture development of {1 0 0} and {1 1 0} preferred orientations in Fe Ga sheets annealed un... more The texture development of {1 0 0} and {1 1 0} preferred orientations in Fe Ga sheets annealed under a sulfur atmosphere and the surface segregation of sulfur were investigated. The two fitted S 2p3/2 peak positions at 161.46 and 163.06 eV by XPS represent the presence of iron sulfide on sheet surfaces. The selective growth of (1 0 0) and (1 1 0) grains was achieved through controlling the segregation of sulfur by annealing in quartz ampoules with varied sulfur content and varied annealing times at 1200 °C.
Journal of Applied Physics, 2008
Journal of Applied Physics, 2012
In this work, magnetization reversal mechanisms in various 35 nm diameter Fe80Ga20/Cu multilayere... more In this work, magnetization reversal mechanisms in various 35 nm diameter Fe80Ga20/Cu multilayered nanowire arrays were studied by a vibrating sample magnetometer (VSM) equipped with vector coils, making it possible to monitor both x- and y-components of the sample moment during reversal. When reversal fields were applied in the low angular range (0 – 60°), all nanowire structures, irrespective of Fe80Ga20 or Cu aspect ratios, experienced reversal by nucleation and propagation of a vortex domain wall. However, when fields were applied in the high angular range of 60–90°, reversal occurred by coherent rotation. Using vector-VSM, it was further shown that in structures with pancake-like Fe80Ga20 segments, the extent to which moments in adjacent segments rotate cooperatively decreased as the Cu thickness increased.