Eric A. Lindgren
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View article: Discriminating the Vote in the 2016 Presidential Election
Discriminating the Vote in the 2016 Presidential Election Open
This research identifies the most important factors that influenced how voters actually cast their votes in the 2016 presidential election. We conducted a canonical linear discriminant analysis of ANES data. Our findings suggest that Obama…
View article: Investigations of pitch-catch angled-beam ultrasonic NDE for characterization of hidden regions of impact damage in composites
Investigations of pitch-catch angled-beam ultrasonic NDE for characterization of hidden regions of impact damage in composites Open
This study explores the use of angled-beam ultrasonic NDE for the potential characterization of hidden regions of impact damage in composites. While simulations of an angled-beam pulse-echo inspections have shown the potential to detect bo…
View article: US Air Force Research Laboratory Perspective on Structural Health Monitoring in Support of Risk Management
US Air Force Research Laboratory Perspective on Structural Health Monitoring in Support of Risk Management Open
The US Air Force (USAF) and US Department of Defense has a long history of research and development in the exploration of on-board sensors being used for detection of damage in aircraft structures. Initial activities can be traced to the e…
View article: The need and approach for characterization - U.S. air force perspectives on materials state awareness
The need and approach for characterization - U.S. air force perspectives on materials state awareness Open
This paper expands on the objective and motivation for NDE-based characterization and includes a discussion of the current approach using model-assisted inversion being pursued within the Air Force Research Laboratory (AFRL). This includes…
View article: Optimization of an angle-beam ultrasonic approach for characterization of impact damage in composites
Optimization of an angle-beam ultrasonic approach for characterization of impact damage in composites Open
Advances in NDE method development are greatly improved through model-guided experimentation. In the case of ultrasonic inspections, models which provide insight into complex mode conversion processes and sound propagation paths are essent…
View article: Fundamentals of angled-beam ultrasonic NDE for potential characterization of hidden regions of impact damage in composites
Fundamentals of angled-beam ultrasonic NDE for potential characterization of hidden regions of impact damage in composites Open
In this study, the use of angled-beam ultrasonic NDE was explored for the potential characterization of the hidden regions of impact damage in composites. Simulated studies using CIVA FIDEL 2D were used to explore this inspection problem. …
View article: Model-based probe state estimation and crack inverse methods addressing eddy current probe variability
Model-based probe state estimation and crack inverse methods addressing eddy current probe variability Open
A model-based calibration process is introduced that estimates the state of the eddy current probe. First, a carefully designed surrogate model was built using VIC-3D® simulations covering the critical range of probe rotation angles, tilt …
View article: Model benchmarking and reference signals for angled-beam shear wave ultrasonic nondestructive evaluation (NDE) inspections
Model benchmarking and reference signals for angled-beam shear wave ultrasonic nondestructive evaluation (NDE) inspections Open
For model benchmark studies, the accuracy of the model is typically evaluated based on the change in response relative to a selected reference signal. The use of a side drilled hole (SDH) in a plate was investigated as a reference signal f…
View article: A Case Study in Left Wing Neo-Populism: The Rise of the Syriza Party in Greece
A Case Study in Left Wing Neo-Populism: The Rise of the Syriza Party in Greece Open
This research considers three approaches to the study of populism: populism as an ideology, populism as a discourse, and populism as a strategy. We highlight the debates between these different approaches. Next, we take the most significan…
View article: US Air Force perspective on validated NDE – Past, present, and future
US Air Force perspective on validated NDE – Past, present, and future Open
The concept of inspection has accompanied aviation since the work of the Wright Brothers. Inspection for both initial quality/materials acceptance and readiness for flight have been coupled with US Air Force (USAF) since its inception as t…
View article: Flaw characterization using inversion of eddy current response and the effect of filters and scan resolution
Flaw characterization using inversion of eddy current response and the effect of filters and scan resolution Open
The objective of this work is to expand eddy current inversion methods to enable estimation of flaw dimensions and orientations for data collected using a variety of scan resolutions and filter configurations. Prior work [1, 2] has demonst…
View article: Explaining the Rise of the UK Independence Party in the 2014 European Parliamentary Elections
Explaining the Rise of the UK Independence Party in the 2014 European Parliamentary Elections Open
Explaining the Rise of the UK Independence Party in the 2014 European Parliamentary Elections Priscilla Southwell, Eric Lindgren; Dustin Ellis Abstract This paper examines European Election Study data in order to determine the saliency and…
View article: Eddy-current NDE inverse problem with sparse grid algorithm
Eddy-current NDE inverse problem with sparse grid algorithm Open
In model-based inverse problems, the unknown parameters (such as length, width, depth) need to be estimated. When the unknown parameters are few, the conventional mathematical methods are suitable. But the increasing number of unknown para…
View article: Model Benchmarking and Reference Signals for Angled-beam Shear Wave Ultrasonic NDE Inspections
Model Benchmarking and Reference Signals for Angled-beam Shear Wave Ultrasonic NDE Inspections Open
NDE modeling and simulation are important tools to support the development and validation of enhanced localization and characterization techniques. Previously, important achievements were made by the USAF to address crack detection in airc…
View article: SHM reliability and implementation – A personal military aviation perspective
SHM reliability and implementation – A personal military aviation perspective Open
Structural Health Monitoring has been proposed as a solution to address the needs of military aviation to reduce the time and cost to perform nondestructive inspections. While the potential to realize significant benefits exist, there are …
View article: Nondestructive damage characterization of complex aircraft structures by inverse methods: Advances in multiscale models
Nondestructive damage characterization of complex aircraft structures by inverse methods: Advances in multiscale models Open
The use of coupled integral equations and anomalous currents allows us to efficiently remove 'background effects' in either forward or inverse modeling. This is especially true when computing the change in impedance due to a small flaw in …
View article: Model-based inverse methods for sizing surface-breaking discontinuities with eddy current probe variability
Model-based inverse methods for sizing surface-breaking discontinuities with eddy current probe variability Open
The objective of this work is to demonstrate and validate model-based inversion techniques to characterize length, depth, width and orientation of surface-breaking cracks using eddy current NDE under varying probe conditions. A series of p…