Engineering Commons^™

A Personal Tribute To Professor Ashok Midha, Larry L. Howell

Faculty Publications

When I received the news that Professor Ashok Midha had passed away, I was grieved by the unexpected news. But I also felt another emotion: gratitude for having known him. I am grateful for him, for the opportunity I had to learn from him, and for the influence he has had on my life and career. I wanted to honor his memory in some way. This document is in response to that desire.

Some of my thoughts at his passing are summarized in the first chapter and the conclusion. The other writing is taken from a draft of my personal …

Assuring Netlist-To-Bitstream Equivalence Using Physical Netlist Generation And Structural Comparison, Reilly Mckendrick, Jeffrey Goeders, Keenan Faulkner

Faculty Publications

Hardware netlists are generally converted into a bitstream and loaded onto an FPGA board through vendor-provided tools. Due to the proprietary nature of these tools, it is up to the designer to trust the validity of the design’s conversion to bitstream. However, motivated attackers may alter the CAD tools’ integrity or manipulate the stored bitstream with the intent to disrupt the functionality of the design. This paper proposes a new method to prove functional equivalence between a synthesized netlist, and the produced FPGA bitstream. The novel approach is comprised of two phases: first, we show how we can utilize implementation …

Coarsening Dynamics Of Ternary Polymer Solutions With Mobility And Viscosity Contrasts, Jan Ulric Garcia, Douglas R. Tree, Alyssa Bagoyo, Tatsuhiro Iwama, Kris T. Delaney, Glenn H. Fredrickson

Faculty Publications

Using phase-field simulations, we investigate the bulk coarsening dynamics of ternary polymer solutions undergoing a glass transition for two models of phase separation: diffusion only and with hydrodynamics. The glass transition is incorporated in both models by imposing mobility and viscosity contrasts between the polymer-rich and polymer-poor phases of the evolving microstructure. For microstructures composed of polymer-poor clusters in a polymer-rich matrix, the mobility and viscosity contrasts significantly hinder coarsening, effectively leading to structural arrest. For microstructures composed of polymer-rich clusters in a polymer-poor matrix, the mobility and viscosity contrasts do not impede domain growth; rather, they change the transient …

Directional Microwave Emission From Femtosecond-Laser Illuminated Linear Arrays Of Superconducting Rings, Thomas J. Bullard, Kyle Frische, Charlie Ebbing, Stephen J. Hageman, John Morrison, John Bulmer, Enam A. Chowdury, Michael L. Dexter, Timothy J. Haugan, Anil K. Patniak

Faculty Publications

We examine the electromagnetic emission from two photo-illuminated linear arrays composed of inductively charged superconducting ring elements. The arrays are illuminated by an ultrafast infrared laser that triggers microwave broadband emission detected in the 1–26 GHz range. Based on constructive interference from the arrays a narrowing of the forward radiation lobe is observed with increasing element count and frequency demonstrating directed GHz emission. Results suggest that higher frequencies and a larger number of elements are achievable leading to a unique pulsed array emitter concept that can span frequencies from the microwave to the terahertz (THz) regime.

Thermal Atomization On Superhydrophobic Surfaces Of Varying Temperature Jump Length, Eric D. Lee, Daniel Maynes, Julie Crockett, Brian D. Iverson

Faculty Publications

This paper presents an experimental study of drop impingement and thermal atomization on hydrophobic and superhydrophobic (SH) surfaces. Superhydrophobic surfaces having both microscale and nanoscale geometry are considered. Microscale SH surfaces are coated with a hydrophobic coating and exhibit micropillars and cavities which are classified using the surface solid fraction and center to center pitch. The solid fraction and pitch values explored in this study range from 0.05-1.0 and 8-60 μm respectively. Nanoscale textured surfaces are created by applying a blanket layer of carbon nanotubes. Both types of surfaces are further classified by a temperature jump length (λ …

Analysis And Requirement Generation For Defense Intelligence Search: Addressing Data Overload Through Human–Ai Agent System Design For Ambient Awareness, Mark C. Duncan, Michael E. Miller, Brett J. Borghetti

Faculty Publications

This research addresses the data overload faced by intelligence searchers in government and defense agencies. The study leverages methods from the Cognitive Systems Engineering (CSE) literature to generate insights into the intelligence search work domain. These insights are applied to a supporting concept and requirements for designing and evaluating a human-AI agent team specifically for intelligence search tasks. Domain analysis reveals the dynamic nature of the ‘value structure’, a term that describes the evolving set of criteria governing the intelligence search process. Additionally, domain insight provides details for search aggregation and conceptual spaces from which the value structure could be …

A Computational Approach For Mapping Electrochemical Activity Of Multi-Principal Element Alloys, Jodie A. Yuwono, Xinyu Li, Tyler D. Dolezal, Adib J. Samin, Javen Qinfeng Shi, Zhipeng Li, Nick Birbilis

Faculty Publications

Multi principal element alloys (MPEAs) comprise an atypical class of metal alloys. MPEAs have been demonstrated to possess several exceptional properties, including, as most relevant to the present study a high corrosion resistance. In the context of MPEA design, the vast number of potential alloying elements and the staggering number of elemental combinations favours a computational alloy design approach. In order to computationally assess the prospective corrosion performance of MPEA, an approach was developed in this study. A density functional theory (DFT) – based Monte Carlo method was used for the development of MPEA ‘structure’; with the AlCrTiV alloy used …

System-Level Noise Performance Of Coherent Imaging Systems, Derek J. Burrell, Joshua H. Follansbee, Mark F. Spencer, Ronald G. Driggers

Faculty Publications

We provide an in-depth analysis of noise considerations in coherent imaging, accounting for speckle and scintillation in addition to “conventional” image noise. Specifically, we formulate closed-form expressions for total effective noise in the presence of speckle only, scintillation only, and speckle combined with scintillation. We find analytically that photon shot noise is uncorrelated with both speckle and weak-to-moderate scintillation, despite their shared dependence on the mean signal. Furthermore, unmitigated speckle and scintillation noise tends to dominate coherent-imaging performance due to a squared mean-signal dependence. Strong coupling occurs between speckle and scintillation when both are present, and we characterize this behavior …

Impact Of Silicon Ion Irradiation On Aluminum Nitride-Transduced Microelectromechanical Resonators, David D. Lynes, Joshua Young, Eric Lang, Hengky Chandrahalim

Faculty Publications

Microelectromechanical systems (MEMS) resonators use is widespread, from electronic filters and oscillators to physical sensors such as accelerometers and gyroscopes. These devices' ubiquity, small size, and low power consumption make them ideal for use in systems such as CubeSats, micro aerial vehicles, autonomous underwater vehicles, and micro-robots operating in radiation environments. Radiation's interaction with materials manifests as atomic displacement and ionization, resulting in mechanical and electronic property changes, photocurrents, and charge buildup. This study examines silicon (Si) ion irradiation's interaction with piezoelectrically transduced MEMS resonators. Furthermore, the effect of adding a dielectric silicon oxide (SiO₂) thin film is …

Augmenting External Surface Pressures’ Predictions On Isolated Low-Rise Buildings Using Cfd Simulations, Md Faiaz Khaled, Aly Mousaad Aly

Faculty Publications

The aim of this paper is to enhance the accuracy of predicting time-averaged external surface pressures on low-rise buildings by utilizing Computational Fluid Dynamics (CFD) simulations. To achieve this, benchmark studies of the Silsoe cube and the Texas Tech University (TTU) experimental building are employed for comparison with simulation results. The paper is structured into three main sections. In the initial part, an appropriate domain size is selected based on the precision of mean pressure coefficients on the windward face of the cube, utilizing Reynolds Averaged Navier-Stokes (RANS) turbulence models. Subsequently, recommendations regarding the optimal computational domain size for an …

Conservative Estimation Of Inertial Sensor Errors Using Allan Variance Data, Kyle A. Lethander, Clark N. Taylor

Faculty Publications

To understand the error sources present in inertial sensors, both the white (time-invariant) and correlated noise sources must be properly characterized. To understand both sources, the standard approach (IEEE standards 647-2006, 952-2020) is to compute the Allan variance of the noise and then use human-based interpretation of linear trends to estimate the separate noise sources present in a sensor. Recent work has sought to overcome the graphical nature and visual-inspection basis of this approach leading to more accurate noise estimates. However, when using noise characterization in a filter, it is important that the noise estimates be not only accurate but …

Influencing Air Force Logisticians' Information Seeking During The Covid-19 Pandemic: The Role Of Organizational Meetings In An Expanded Prism Framework, Matthew D. Roberts, Christopher T. Price, Seong-Jong Joo

Faculty Publications

Purpose: This research aims to understand how organizational workplace meetings surrounding the COVID-19 pandemic impacted logistics Airmen across the United States Air Force and how these meetings impacted their risk seeking behavior on social media.

Design/methodology/approach: This survey research tested an extended Planned Risk Information Risk Seeking Model (PRISM) with organizational meetings as an antecedent to determine if current meetings influenced an Airman's perceived behavioral control, attitude toward seeking, subjective norms, knowledge sufficiency and intention to seek information regarding COVID-19.

Findings: Results of the CFA showed that the expanded PRISM model had good model fit. Additionally, using …

Small-Scale Testing Of Passive Fire Protection Systems For Structures On The Wildland-Urban Interface, Makenzie Wilson, Thomas H. Fletcher, Taylor J. Sorensen

Faculty Publications

The average intensity and frequency of wildland fires have been on the rise over the years due to climate change. This, in combination with recent expansion and growth of rural areas, has led to an increased risk of wildfire damage for structures in the Wildland-Urban Interface (WUI). This paper proposes a permanent passive fire protection system that is built into the structure. A flame-resistant material would be attached to the sheathing underneath the roofing and siding material. This system would allow the easily replaceable exterior components of the structure to burn while leaving the interior of the structure protected. Small-scale …

Spectral Broadening Effects On Pulsed-Source Digital Holography, Steven A. Owens, Mark F. Spencer, Glen P. Perram

Faculty Publications

Using a pulsed configuration, a digital-holographic system is setup in the off-axis image plane recording geometry, and spectral broadening via pseudo-random bit sequence is used to degrade the temporal coherence of the master-oscillator laser. The associated effects on the signal-to-noise ratio are then measured in terms of the ambiguity and coherence efficiencies. It is found that the ambiguity efficiency, which is a function of signal-reference pulse overlap, is not affected by the effects of spectral broadening. The coherence efficiency, on the other hand, is affected. As a result, the coherence efficiency, which is a function of effective fringe visibility, is …

Oxidation Of Hafnium Diboride—Silicon Carbide At 1500 °C In Air; Effect Of Compressive Stress, Anthony J. Degregoria, Marina B. Ruggles-Wrenn, Glen E. Pry

Faculty Publications

The long-term oxidation behavior of HfB₂ and of HfB₂-20 vol.% SiC was studied. Test samples of each material were oxidized at 1500 °C in air using a box furnace. The exposure times were 0, 0.5, 1, 2, 3, 6, 9, 12, 15, 30, 45 and 90 h. Weight gain, oxide scale composition and oxide scale thickness were characterized for both materials. Crystal structure of the surface scales was analyzed using x-ray diffraction. Oxide scales were further characterized via scanning electron microscopy with energy dispersive spectroscopy analysis. For HfB₂ the oxide scale consists predominantly of porous HfO …

Complex Systems Methods Characterizing Nonlinear Processes In The Near-Earth Electromagnetic Environment: Recent Advances And Open Challenges, Georgios Balasis, Michael A. Balikhin, Sandra C. Chapman, Giuseppe Consolini, Ioannis A. Daglis, Reik V. Donner, Jürgen Kurths, Milan Paluš, Jakob Runge, Bruce T. Tsurutani, Dimitris Vassiliadis, Simon Wing, Jesper W. Gjerloev, Jay Johnson, Massimo Materassi, Tommaso Alberti, Constantinos Papadimitriou, Pouya Manshour, Adamantia Zoe Boutsi, Mirko Stumpo

Faculty Publications

Learning from successful applications of methods originating in statistical mechanics, complex systems science, or information theory in one scientific field (e.g., atmospheric physics or climatology) can provide important insights or conceptual ideas for other areas (e.g., space sciences) or even stimulate new research questions and approaches. For instance, quantification and attribution of dynamical complexity in output time series of nonlinear dynamical systems is a key challenge across scientific disciplines. Especially in the field of space physics, an early and accurate detection of characteristic dissimilarity between normal and abnormal states (e.g., pre-storm activity vs. magnetic storms) has the potential to vastly …

The Characteristics Of Successful Military It Projects: A Cross-Country Empirical Study, Helene Berg, Jonathan D. Ritschel

Faculty Publications

No abstract provided.

Electrically-Evoked Referred Sensations Induce Embodiment Of Rubber Limb, Anthony Nguyen, Brooke Draggoo, Brooklyn Tobias, Payton Dubose, Katharine Polasek

Faculty Publications

Introduction: Electrical stimulation is increasingly relevant in a variety of medical treatments. In this study, the quality of referred sensations evoked using surface electrical stimulation was evaluated using the rubber hand and foot illusions.

Methods: The rubber hand and foot illusions were attempted under 4 conditions: (1) multi-location tapping; (2) one-location tapping; (3) electrical stimulation of sensation referred to the hand or foot; (4) asynchronous control. The strength of each illusion was quantified using a questionnaire and proprioceptive drift, where a stronger response suggested embodiment of the rubber limb.

Results: 45 able-bodied individuals and two individuals with amputations participated in …

Accurate Covariance Estimation For Pose Data From Iterative Closest Point Algorithm, Rick H. Yuan, Clark N. Taylor, Scott L. Nykl

Faculty Publications

One of the fundamental problems of robotics and navigation is the estimation of the relative pose of an external object with respect to the observer. A common method for computing the relative pose is the iterative closest point (ICP) algorithm, where a reference point cloud of a known object is registered against a sensed point cloud to determine relative pose. To use this computed pose information in downstream processing algorithms, it is necessary to estimate the uncertainty of the ICP output, typically represented as a covariance matrix. In this paper, a novel method for estimating uncertainty from sensed data is …

Domain Restriction Zones: An Evolution Of The Military Exclusion Zone, Cole M. Mooty, Robert A. Bettinger, Mark G. Reith

Faculty Publications

Since the early part of the twenty-first century, US adversaries have expanded their military capabilities within and their access to new warfighting domains. When faced with the growth of adversaries’ asymmetric capabilities, the means, tactics, and strategies previously used by the US military lose their proportional effectiveness. To avoid such degradation of capability, the operational concept of the military exclusion zone (MEZ) should be revised to suit the modern battlespace while also addressing the shifts in national policy that encourage diplomacy over military force. The concept and development of domain restriction zones (DRZs) increase the relevancy of traditional MEZs in …

Intrinsic Point Defects (Vacancies And Antisites) In Cdgep2 Crystals, Timothy D. Gustafson, Nancy C. Giles, Peter G. Schunemann, Kevin T. Zawilski, Kent L. Averett, Jonathan E. Slagle, Larry E. Halliburton

Faculty Publications

Cadmium germanium diphosphide (CdGeP₂) crystals, with versatile terahertz-generating properties, belong to the chalcopyrite family of nonlinear optical materials. Other widely investigated members of this family are ZnGeP₂ and CdSiP₂. The room-temperature absorption edge of CdGeP₂ is near 1.72 eV (720 nm). Cadmium vacancies, phosphorous vacancies, and germanium-on-cadmium antisites are present in as-grown CdGeP₂ crystals. These unintentional intrinsic point defects are best studied below room temperature with electron paramagnetic resonance (EPR) and optical absorption. Prior to exposure to light, the defects are in charge states that have no unpaired spins. Illuminating a CdGeP_{2 …}

Empowering Student Success: Unlocking The Potential Of Project-Based Steel Design Education, Aly Mousaad Aly

Faculty Publications

In the pursuit of student success, it is essential to acknowledge that a singular teaching style does not universally cater to all students. The educator's crucial role lies in creating an optimal learning environment that fosters students' endeavors to excel. This endeavor transcends mere classroom success or employment prospects, encompassing a broader impact on societal well-being. An experiential learning approach, where students actively engage in practical tasks, emerges as the most effective mode of instruction. Integrating project-based learning activities into the curriculum holds immense potential for enhancing student learning. Additionally, the utilization of analysis software tools like FTool and STAAD …

Optimal Estimation Inversion Of Ionospheric Electron Density From Gnss-Pod Limb Measurements: Part I-Algorithm And Morphology, Dong L. Wu, Nimalan Swarnalingam, Cornelius Csar Jude H. Salina, Daniel J. Emmons, Tyler C. Summers, Robert Gardiner-Garden

Faculty Publications

GNSS-LEO radio links from Precise Orbital Determination (POD) and Radio Occultation (RO) antennas have been used increasingly in characterizing the global 3D distribution and variability of ionospheric electron density (Ne). In this study, we developed an optimal estimation (OE) method to retrieve Ne profiles from the slant total electron content (hTEC) measurements acquired by the GNSS-POD links at negative elevation angles (ε < 0°). Although both OE and onion-peeling (OP) methods use the Abel weighting function in the Ne inversion, they are significantly different in terms of performance in the lower ionosphere. The new OE results can overcome the large Ne oscillations, sometimes negative values, seen in the OP retrievals in the E-region ionosphere. In the companion paper in this Special Issue, the HmF2 and NmF2 from the OE retrieval are validated against ground-based ionosondes and radar observations, showing generally good agreements in NmF2 from all sites. Nighttime hmF2 measurements tend to agree better than the daytime when the ionosonde heights tend to be slightly lower. The OE algorithm has been applied to all GNSS-POD data acquired from the COSMIC-1 (2006–2019), COSMIC-2 (2019–present), and Spire (2019–present) constellations, showing a consistent ionospheric Ne morphology. The unprecedented spatiotemporal sampling of the ionosphere from these constellations now allows a detailed analysis of the frequency–wavenumber spectra for the Ne variability at different heights. In the lower ionosphere (~150 km), we found significant spectral power in DE1, DW6, DW4, SW5, and SE4 wave components, in addition to well-known DW1, SW2, and DE3 waves. In the upper ionosphere (~450 km), additional wave components are still present, including DE4, DW4, DW6, SE4, and SW4. The co-existence of eastward- and westward-propagating wave4 components implies the presence of a stationary wave4 (SPW4), as suggested by other earlier studies. Further improvements to the OE method are proposed, including a tomographic inversion technique that leverages the asymmetric sampling about the tangent point associated with GNSS-LEO links.

Intrinsically Stretchable Three Primary Light-Emitting Films Enabled By Elastomer Blend For Polymer Light-Emitting Diodes, Min Woo Jeong, Jin Hyun Ma, Jae Sung Shin, Jun Su Kim, Guorong Ma, Tae Uk Nam, Xiaodan Gu, Seong Jun Kang, Jin Young Oh

Faculty Publications

Intrinsically stretchable light-emitting materials are crucial for skin-like wearable displays; however, their color range has been limited to green-like yellow lights owing to the restricted stretchable light-emitting materials (super yellow series materials). To develop skin-like full-color displays, three intrinsically stretchable primary light-emitting materials [red, green, and blue (RGB)] are essential. In this study, we report three highly stretchable primary light-emitting films made from a polymer blend of conventional RGB light-emitting polymers and a nonpolar elastomer. The blend films consist of multidimensional nanodomains of light-emitting polymers that are interconnected in an elastomer matrix for efficient light-emitting under strain. The RGB blend …

Imparting Systems Engineering Experience Via Interactive Fiction Serious Games, Thomas C. Ford, David Long, Echo Ford *

Faculty Publications

Serious games for education are becoming increasing popular. Interactive fiction games are some of the most popular in app stores and are also beginning to be heavily used in education to teach analysis and decision-making. Noting that it is difficult for systems engineers to experience all necessary situations which prepare them for the role of a chief engineer, in this paper, we explore the use of interactive fiction serious games to impart systems engineering experience and to teach systems engineering principles. The results of a cognitive viability, qualitative viability, and replayability analysis of 14 systems engineering serious games developed in …

Estimating Intermittency Significance By Means Of Surrogate Data: Implications For Solar Wind Turbulence, Eliza Teodorescu, Marius Mihai Echim, Jay Johnson

Faculty Publications

Introduction: Intermittency is a property of turbulent astrophysical plasmas, such as the solar wind, that implies irregularity and fragmentation, leading to non-uniformity in the transfer rate of energy carried by nonlinear structures from large to small scales. We evaluated the intermittency level of the turbulent magnetic field measured by the Parker Solar Probe (PSP) in the slow solar wind in the proximity of the Sun during the probe’s first close encounter. Methods: A quantitative measure of intermittency could be deduced from the normalized fourth-order moment of the probability distribution functions, the flatness parameter. We calculated the flatness of the magnetic …

Nonsolvent-Induced Phase Separation Inside Liquid Droplets, Rami Alhasan, Tanner A. Wilcoxson, Dakota S. Banks, Sion Jung, Douglas R. Tree

Faculty Publications

Nonsolvent-induced phase separation (NIPS) is a popular method for creating polymeric particles with internal microstructure, but many fundamental questions remain surrounding the kinetics of the complex coupled mass transfer and phase separation processes. In this work, we use simulations of a phase-field model to examine how (i) finite domain boundaries of a polymer droplet and (ii) solvent/nonsolvent miscibility affect the NIPS process. To isolate the effects of phase separation kinetics and solvent/nonsolvent mass transfer on the NIPS process, we study two different cases. First, we investigate droplet concentrations that originate inside the two-phase region, where phase separation kinetics alone governs …

Effects Of Individual Strategies For Resource Access On Collaboratively Maintained Irrigation Infrastructure, Jordan L. Stern, Afreen Siddiqi, Paul N. Grogan

Faculty Publications

Built infrastructure for water and energy supply, transportation, and other such services underpins human well-being and socioeconomic development. A fundamental understanding of how infrastructure design and user strategies interact can guide important design decisions as well as policy formulation for ensuring long-term infrastructure viability in conjunction with improved individual user benefits. In this work, an agent based model (ABM) is developed to study this issue for the specific case of irrigation canals. Cooperatively maintained irrigation canals serve essential roles in sustaining agriculture-based economies in many regions. Canal system design can strongly affect benefits derived by distributed users, regional agricultural output, …

User Guide For Urban Canopy Modeling In Wrf. Version 1.0, Corey L. Smithson, Natalie J. White, Hans R. Klomp, Eric C. Monson, Bradley R. Adams

Faculty Publications

Researchers at Brigham Young University (BYU) have developed this guide for running a WRF simulation using a single layer urban canopy model (UCM). This was developed specifically for the Greater Salt Lake Area but is adaptable to other urban areas. This guide includes information on running WRF simulations to study theoretical urban growth scenarios.

Vortex Particle Method For Electric Ducted Fan In Non-Axisymmetric Flow, Eduardo Alvarez, Cibin Joseph, Andrew Ning

Faculty Publications

The vortex particle method has been reformulated in recent work as a large eddy simulation (LES) in a scheme that is both meshless and numerically stable, solving long-standing issues of numerical stability. In this study, we build upon this meshless LES scheme to create a simulation framework for electric ducted fans. This poses the challenge of introducing solid boundaries in the vorticity form of the Navier-Stokes equations without a mesh. Rotor blades are introduced in our computational domain through an actuator line model (ALM) following well-established practices for LES. A novel, vorticity-based, actuator surface model (ASM) is developed for the …