Engineering Commons^™

Boiling Crisis Is A Consequence Of Thermal Runaway In The Substrate Due To Degradation Of Nucleate Boiling Heat Transfer, Manohar Bongarala, Justin A. Weibel, Suresh V. Garimella

CTRC Research Publications

Chaotic bubble interactions during vigorous boiling have foiled attempts at an accurate mechanistic understanding of this important industrial transport process. Prediction of the boiling crisis (dryout) that occurs due to the spontaneous merger of bubbles into an insulating vapor film at critical heat flux remains an unsolved challenge. This work diagnoses the dryout process using synchronized high-resolution spatiotemporal heat flux and phase data, obtained via through-substrate infrared and visual inspection. We examine prevailing theories for the boiling crisis and provide evidence to rule out all but one. The boiling crisis is found to be a consequence of a peak in …

The Shoulder Effect In The Stagnation Zone For Temperature-Controlled Jet Impingement Transition Boiling Of Submerged Dielectric Fluid, Tyler P. Stamps, Justin A. Weibel

CTRC Research Publications

Two-phase jet impingement is capable of high heat transfer coefficients and high boiling critical heat flux (CHF) limits, making it a suitable technology for electronics immersion cooling applications. Previous studies have focused on the heat-flux-controlled nucleate boiling performance of an impingement jet up to the CHF. Exploration of other boiling regimes that occur under temperature-controlled surfaces is of equal fundamental importance. It has been shown for free jets that a high and consistent heat flux can be dissipated over a wide range of surface superheats in the transition boiling regime when the surface is temperature-controlled. This so-called “shoulder effect”, or …

Hands-On For Whom?, Isabella Stuopis, Avneet Hira

Journal of Pre-College Engineering Education Research (J-PEER)

Hands-on technology-enhanced pedagogies have been hailed as a panacea for engaging K–12 students in engineering. We unpack how the entanglement of the sociopolitical with the educational, namely how factors pertaining to resources and individual characteristics, impact engagement with such pedagogies. In particular, we expand upon how school funding, teacher preparation and support, access to out-of- school resources, and family background impact the in-and out-of- school resources students have access to. Further, we explain how characteristics such as a sense of belonging, pedagogical approaches, and assumptions and gatekeeping by adults impact students’ ability to engage with hands-on engineering education. In doing …

Smart Airports: Artificial Intelligence–Enabled Internet Of Things Networks Using Blockchain Technology, Edwin Ongola

Journal of Aviation Technology and Engineering

This article provides a perspective on how an internet of heterogeneous self-service airport terminal systems can be used for data collection, which is stored on a private or consortium blockchain depending on the ownership or operations of an airport or both. Such a setup would help to increase efficiency, reduce costs, and improve traveler experience at airport terminals. Moreover, it would allow airports to gather data directly from passengers as opposed to waiting to receive the same data from airlines. Subsequently, this data, now on a blockchain system, becomes a data source for other applications such as machine learning. In …

Computational Fluid Dynamics Visualization For Unmanned Aerial Systems In Bridge Inspections, Kristoffer B. Borgen, John Mott

Journal of Aviation Technology and Engineering

Bridge inspections are an expensive and time-consuming process, varying significantly with a bridge’s style, height, width, and length. Inspections create interruptions that interfere with bridge use, as the examination requires partial or total closure, causing traffic delays. Unmanned aerial system (UAS) use has increased significantly over the past decade, including assistance and coordination during bridge inspections. However, the impact on a UAS from high winds and turbulent airflows induced by a bridge’s structure can decrease flight safety during inspections. Visualization of these hazards is difficult for UAS operators; therefore, a process to estimate the velocity and locations of these hazardous …

Energy Safety Management: A Training Model To Improve Flight Safety, Juan R. Merkt, Matthijs H. J. Amelink, David G. Sizoo

Journal of Aviation Technology and Engineering

Failing to properly manage an airplane’s energy state can be unforgiving. Mismanagement of mechanical energy (altitude and/or airspeed) is a contributing factor to three common types of fatal accidents in aviation: loss of control in flight, approach and landing accidents, and controlled flight into terrain. Recognizing the importance of energy management, the Federal Aviation Administration has incorporated new elements into the Airman Certification Standards, emphasizing knowledge of energy management concepts and the consequences of mishandling an airplane’s energy state. Unfortunately, no adequate guidance has been available in terms of defining key energy management concepts or suggesting how these should be …

Biocompatibility Of Mussel-Inspired Water-Soluble Tissue Adhesives, Aishwarya V. Menon, Amelia A. Putnam-Neep, Caitlin E. Brown, Christa J. Crain, Gert Breur, Sanjeev K. Narayanan, Jonathan Wilker, Julie C. Liu

School of Chemical Engineering Faculty Publications

Wound closure in surgeries is traditionally achieved using invasive methods such as sutures and staples. Adhesion-based wound closure methods such as tissue adhesives, sealants, and hemostats are slowly replacing these methods due to their ease of application. Although several chemistries have been developed and used commercially for wound closure, there is still a need for better tissue adhesives from the point of view of toxicity, wet-adhesion strength, and long-term bonding. Catechol chemistry has shown great promise in developing wet-set adhesives that meet these criteria. Herein, we have studied the biocompatibility of a catechol-based copolymer adhesive, poly([dopamine methacrylamide]-co-[methyl methacrylate]-co-[poly(ethylene glycol) methyl …

A Review Of Computational Fluid Dynamics Approaches Used To Investigate Lubrication Of Rolling Element Bearings, Farshid Sadeghi, Ujjawal Arya, Saeed Aamer, Andreas Meinel

School of Mechanical Engineering Faculty Publications

Optimizing bearing performance is based on effective lubrication, especially in high-speed machinery, where minimizing churning and drag losses is of significant importance. Over the past few decades, extensive research has been conducted into the better understanding of different aspects of bearing lubrication. These investigations have employed a combination of experimental methods and advanced computational fluid dynamics (CFD) models. This article provides a comprehensive overview of critical aspects of bearing lubrication, with a specific emphasis on recent advances in CFD models. Lubricant flow and distribution patterns are discussed while examining their impact on drag and churning losses. An extensive discussion is …

Safety In P–12 Engineering Courses Within The Southern United States, Tyler S. Love

Journal of Pre-College Engineering Education Research (J-PEER)

Engineering education programs, especially at the P–12 level, pose inherent legal and ethical responsibilities pertaining to safety that cannot be ignored. Cultivating safer practices and habits during the design and hands-on development of engineering solutions starts well before students enter higher education engineering programs. P–12 engineering education programs play a critical role in enhancing safety awareness, developing safer habits, and improving safety culture, which has an influence on the safety practices that students carry with them into higher education programs and the workplace. This study analyzed the safety factors and accident occurrences reported by 305 P–12 engineering educators from the …

Feasibility Of Eeg Based Detection Of Ischemic Stroke: Studies In A Simple Computational Model, Charles F. Babbs

Weldon School of Biomedical Engineering Faculty Working Papers

Objective: To explore quantitatively, using streamlined mathematics, how transmembrane potential differences across cell bodies of individual cortical neurons could act to produce the skin surface potentials of the electroencephalogram (EEG), and how ischemic stroke might be detected using EEGs in prehospital settings. Methods: From fundamental principles of electrostatics, anatomy, and physiology, one can characterize the strength of apparent dipoles created during activation of the cell bodies of individual cortical neurons. The transient dipole strength in a cortical neuron depends upon the size and surface area of its cell body, its capacitance, and the difference in transmembrane electrical potentials appearing across …

Learning By Evaluating: An Exploration Of Optimizing Design-Based Instruction, Scott Thorne, Nathan Mentzer, Greg J. Strimel, Scott R. Bartholomew, Jason A. Ware

School of Engineering Technology Faculty Publications

Learning by Evaluating (LbE) is an instructional approach that involves students making comparative judgements of pairs of artifacts, such as student work, portfolios, prototypes, or curated images related to a topic of instruction to enhance critical thinking and decision-making skills. Situated as a primer for learning, the efficacy of LbE stems from actively engaging students in the evaluation process, scaffolding their learning, fostering self-reflection in decision-making, and facilitating the transfer of acquired skills and concepts to academic contexts and project work. However, there is an opportunity to gain deeper insights into classroom integration of LbE and the factors that may …

Ai-Based Concept Inventories: Using Cognitive Diagnostic Computer Adaptivetesting In Lasso For Classroom Assessment, Jason Morphew, Amirreza Mehrabi, Ben Van Dusen, Jayson Nissen

School of Engineering Education Faculty Publications

Research-based concept inventories, such as the Force Concept Inventory, the Force and Motion Conceptual Evaluation, or the Energy and Momentum Conceptual Survey have played a pivotal role in designing and evaluating instruction in introductory physics courses. While these concept inventories have helped identify inequity in course instruction and have led to improved pedagogical methods, concerns about their ability to provide actionable feedback for formative assessment remain. In addition, using the same questions for both a pre- and a post- assessment leaves the potential for students learning the correct answers without undergoing conceptual change. To address these issues, we designed a …

Protocol For Recording Neural Activity Evoked By Electrical Stimulation In Mice Using Two-Photon Calcium Imaging, Seungbin Park, Megan Lipton, Yujiao J. Sun, Maria Dadarlat

Purdue University Libraries Open Access Publishing Fund

Electrical stimulation provides a clinically viable approach for treating neurological disorders. Here, we present a protocol for recording neural activity evoked by electrical stimulation in mice using two-photon calcium imaging. We detail steps for chronically implanting a head fixation bar, a stimulating electrode, and a glass imaging window.We additionally describe the procedures for viral injections and awake head-fixed recordings.

Comparing Human Text Classification Performance And Explainability With Large Language And Machine Learning Models Using Eye-Tracking, Jeevithashree Divya Venkatesh, Aparajita Jaiswal, Gaurav Nanda

Purdue University Libraries Open Access Publishing Fund

To understand the alignment between reasonings of humans and artificial intelligence (AI) models, this empirical study compared the human text classification performance and explainability with a traditional machine learning (ML) model and large language model (LLM). A domain-specific noisy textual dataset of 204 injury narratives had to be classified into 6 cause-of-injury codes. The narratives varied in terms of complexity and ease of categorization based on the distinctive nature of cause-of-injury code. The user study involved 51 participants whose eye-tracking data was recorded while they performed the text classification task. While the ML model was trained on 120,000 pre-labelled injury …

Stretching The Limits Of Mri—Stretchable And Modular Coil Array Using Conductive Thread Technology, Folk W. Narongrit, Thejas Vishnu Ramesh, Joseph V. Rispoli

Purdue University Libraries Open Access Publishing Fund

Objective: We propose a modular stretchable coil design using conductive threads and commercially available embroidery machines. The coil design increases customizability of coil arrays for individual patients and each body part. Methods: Eight rectangular coils were constructed with custom-fabricated stretchable tinsel copper threads incorporated onto textile. Tune, match, and detune circuits were incorporated on the coil. A hook-and-loop mechanism was used to attach and decouple the modular coils. Phantom and in vivo scans at various anatomical flexion angles were acquired to highlight performance, and a temperature test was performed to verify safety. Results: In vivo MRI experiments demonstrate high sensitivity …

A Novel Research Design: Using Multilevel Discrete-Time Survival Analysis To Investigate The Effect Of Calculus I On Engineering Student Persistence, Hayaam Osman, Matthew Ohland

School of Engineering Education Faculty Publications

The persistence of engineering students through graduation continues to be a concern in higher education. Previous studies have highlighted a link between students' performance in introductory mathematics courses and graduation rates. Focusing on a crucial foundational course within the engineering curriculum, the purpose of this study is to investigate how students’ performance in Calculus I impact their persistence in the engineering program. Utilizing data from 22 diverse educational institutions using Multiple-Institution Database for Investigating Engineering Longitudinal Development (MIDFIELD), multilevel discrete-time survival analysis is employed to examine the longitudinal persistence patterns among the nested structure of students within institutions. Discrete-time analysis …

Optical Fiber Sensor-Embedded Strands For Long-Term Monitoring Of Post-Tensioned Tendons In Bridge Elements, Christopher S. Williams, Pinar Okumus, Manan B. Khatri, Mi Jin Jung

Bowen Laboratory Research Reports

Tendon forces are fundamental to the performance of post-tensioned (PT) bridges. Therefore, monitoring tendon forces is important for understanding the health of PT bridge elements and evaluating the condition of prestressing strands. Implementing a reliable method to monitor PT tendons during the service life of the structure, however, is a challenge. The ideal technology should provide a measurement of prestress (or strain) over the length of the tendon and not be limited to measurement only at discrete locations.

When installed along the length of PT tendons, optical fiber sensors provide a promising means to overcome many of the challenges of …

Dynamics Of An Airplane Wheel At Touchdown, Pirooz Mohazzabi, Sophia Gentile, Cristian Marquez

Journal of Aviation Technology and Engineering

The dynamics of tire skidding and wear of a commercial airplane during touchdown is discussed, and a simple analytical model is presented. It is suggested that prespinning of the wheels prior to touchdown is not only possible but also practical to prevent tire wear and damage to the runway and the ensuing environmental issues.

Dna G-Quadruplexes As Targets For Natural Product Drug Discovery, Kai-Bo Wang, Yingying Wang, Jonathan Dickerhoff, Danzhou Yang

Purdue University Libraries Open Access Publishing Fund

DNA guanine (G)-quadruplexes (G4s) are unique secondary structures formed by two or more stacked G-tetrads in G-rich DNA sequences. These structures have been found to play a crucial role in highly transcribed genes, especially in cancer-related oncogenes, making them attractive targets for cancer therapeutics. Significantly, targeting oncogene promoter G4 structures has emerged as a promising strategy to address the challenge of undruggable and drug-resistant proteins, such as MYC, BCL2, KRAS, and EGFR. Natural products have long been an important source of drug discovery, particularly in the fields of cancer and infectious diseases. Noteworthy progress has recently been made in the …

Extreme Image Transformations Improve Latent Representations In Machines, Girik Malik, Ennio Mingolla

MODVIS Workshop

Shuffling pixels in an image helps machines to learn a more robust object representation. To probe the strategies used by humans and machines for object recognition, we introduce Extreme Image Transformations (EITs). Machines rely heavily on exploiting low-level features like color and texture, so their performance degrades on out-of-distribution and adversarial inputs. Humans depend on high-level features like shapes and contours, making them relatively robust to image distortions. EITs systematically shuffle the pixels in an image, parameterized by the size of grids, probability of shuffle and binary block movement, distorting the structure of objects at both local and global levels. …

Facilitation In Pattern Motion Perception Of Self-Operated Stimuli Explained By Adaptive Contrast Normalization, Fulvio Missoni, Francesca Peveri, Andrea Canessa, Giulia Sedda, Vittorio Sanguineti, Silvio P. Sabatini

MODVIS Workshop

Movement can affect the way we make sense of complex visual information. To investigate this issue, we designed an experiment to assess changes of plaid motion perception threshold after a period of sensorimotor contingency experience. We found that movement training facilitates combination of elementary motion cues into a global motion percept. No changes in perceptual thresholds are observed in a passive visual condition. A Bayesian model suggested a reduction, after training, of the cross-talk between two gratings with unbalanced contrasts in corresponding sensory channels. To test plausible neural mechanisms for active reduction of cross-talk in cortical representation of complex visual …

Explaining The Staircase Gelb Illusion, Simultaneous Contrast, And Perceptual Fading Of Stabilized Images With A Neural Model Driven By Fixational Eye Movements, Michael E. Rudd

MODVIS Workshop

A neural model of lightness computation driven by fixational eye movements is described and used to simulate various lightness phenomenon, including the Staircase Gelb illusion and its variants, simultaneous contrast, the Chevreul illusion, and perceptual fading of stabilized images. The model provides a precise account of the lightness matches from several experiments, with an overall error of only 1.5%. In the model, spatial maps of transient ON and OFF cell activations—produced as the eyes traverse the visual scene—are sorted by eye movement direction in visual cortex. At a subsequent processing stage, the activations within these maps are summed across space …

Algebraic Speed Estimation For Sensorless Induction Motor Control: Insights From An Electric Vehicle Drive Cycle, Jorge Neira-Garcia, Andres Beltran-Pulido, John Cortes-Romero

Purdue University Libraries Open Access Publishing Fund

Induction motors (IMs) must meet high reliability and safety standards in mission-critical applications, such as electric vehicles (EVs), where sensorless control strategies are fundamental. However, sensorless rotor speed estimation demands improvements to overcome filtering distortions, tuning complexities, and sensitivity to IM model mismatch. Algebraic methods offer inherent filtering capabilities and design flexibility to address these challenges without introducing additional dynamics into the control system. The objective of this paper is to provide an algebraic estimation strategy that yields an accurate rotor speed estimate for sensorless IM control. The strategy includes an algebraic estimator with single-parameter tuning and inherent filtering action. …

The Mechanism By Which Thermal Coupling Leads To An Asymptotic Maldistribution Stability Boundary For Flow Boiling In Parallel Microchannels, Md Emadur Rahman, Justin A. Weibel

CTRC Research Publications

Phase change heat transfer processes are attractive for the efficient thermal management of advanced semiconductor devices, with flow boiling in parallel microchannel heat sinks being one promising solution. However, there are several implementation challenges associated with two-phase flow in parallel microchannels, particularly flow maldistribution, which can adversely affect performance and reliability. Two-phase flow models can be useful in predicting and understanding the instability mechanisms that leads to maldistribution, such that parametric performance trends and safe regions of operation can be identified. Channel-to-channel thermal coupling has been shown to alleviate maldistribution, but it is not yet understood why this effect is …

Pso Scoring Instruction Guide, Adrian Gentry, Tiantian Li, Eric Holloway, Kerrie A. Douglas, Julie P. Martin

School of Engineering Education Working Papers

This document is a scoring guide to assist higher-education administrators, faculty, and researchers who wish to use the Professional Skills Opportunities instrument (PSO). There are four aspects, or factors, that the PSO is intended to measure relative to engineering undergraduate students’ opportunities to practice professional skills and an overall PSO score. Detailed scoring instructions are provided. The PSO was developed to assess students’ opportunities to develop and practice a range of professional skills. Utilizing a rigorous instrument development process, the PSO was shown to be a tool that can reliably and validly be used to assess engineering undergraduate students' professional …

Sparse Ensemble Networks For Hypserspectral Image Classification, Rakesh Kumar Iyer, Okan Ersoy

Department of Electrical and Computer Engineering Technical Reports

We explore the efficacy of sparsity and ensemble model in the classification of hyperspectral images, a pivotal task in remote sensing applications. While Convolutional Neural Networks (CNNs) and Transformer models have shown promise in this domain, each exhibits distinct limitations; CNNs excel in capturing the spatial/local features but falter to capture spectral features, whereas Transformers captures the spectral features at the expense of spatial features. Furthermore, the computational cost associated with training several independent CNN and Transformer networks becomes expensive. To address these limitations, we propose a novel ensemble framework comprising pruned CNNs and Transformers, optimizing both spatial and spectral …

Estimating Effects Of Tourism Using Multiple Data Sources: The Miranda Tool As Part Of A Spatial Decision Support System For Sustainable Destination Development, Tobias Heldt

GSTC Academic Symposium - In conjunction with the GSTC Global Conference

Planning for sustainable mobility and destination development in rural areas is increasingly important when tourism grows in numbers. A key to address the challenge of transformation and adaptation of local communities to mitigate adverse effects in seasonal peak hours like traffic congestion, power failure, waste management and sewage flooding, is to properly estimate the number of visitors to a destination.

The problem of estimating tourism numbers is a known challenge since, for example, guest nights statistics are in-complete and non-commercial lodging (sharing solutions) are increasing. Recently, the promising utilization of mobile phone data has emerged as a means to estimate …

Achieving Room Temperature Plasticity In Brittle Ceramics Through Elevated Temperature Preloading, Chao Shen, Jin Li, Tongjun Niu, Jaehun Cho, Zhongxia Shang, Yifan Zhang, Anyu Shang, Bo Yang, Ke Xu, R. Edwin Garcia, Haiyan Wang, Xinghang Zhang

Purdue University Libraries Open Access Publishing Fund

Ceramic materials with high strength and chemical inertness are widely used as engineering materials. However, the brittle nature limits their applications as fracture occurs before the onset of plastic yielding. There has been limited success despite extensive efforts to enhance the deformability of ceramics. Here we report a method for enhancing the room temperature plastic deformability of ceramics by artificially introducing abundant defects into the materials via preloading at elevated temperatures. After the preloading treatment, single crystal (SC) TiO2 exhibited a substantial increase in deformability, achieving 10% strain at room temperature. SC α-Al2O3 also showed plastic deformability, 6 to 7.5% …

Optimal Aoi For Systems With Queueing Delay In Both Forward And Backward Directions, Chih-Chun Wang

Department of Electrical and Computer Engineering Technical Reports

Age-Of-Information (AoI) is a metric that focuses directly on the application-layer objectives, and a canonical AoI minimization problem is the update-through-queues models. Existing results in this direction fall into two categories: The open-loop setting for which the sender is oblivious of the packet departure time, versus the closed-loop setting for which the decision is based on instantaneous Acknowledgment (ACK). Neither setting perfectly reflects modern networked systems, which almost always rely on feedback that experiences some delay. Motivated by this observation, this work subjects the ACK traffic to a second queue so that the closed-loop decision is made based on delayed …

Deficiencies In Safe Practices By Pilots Operating General Aviation Aircraft In Weather Conducive For Icing, Douglas Boyd Phd, Thomas Guinn Phd

Journal of Aviation Technology and Engineering

Introduction: Flights of general aviation aircraft in icing conditions pose safety hazards especially since few airplanes are equipped with ice protection systems (FIKI). Herein, we sought to answer the following questions not previously addressed: (i) Has the general aviation icing-related accident rate declined over time? (ii) Which phase(s) of flight lead(s) to the highest fraction of fatal accidents? (iii) Do general aviation pilots adhere to safe practices when operating in forecasted icing?

Methods: Retrospectively, icing-related accidents were per the National Transportation Safety Board database. Prospectively, non-FIKI single-engine airplanes, operating in forecasted icing, were tracked (January–March 2023) using FlightAwareR. Presumptive icing …