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Full-Text Articles in Engineering
Electron-Phonon Interaction Mediated Gigantic Enhancement Of Thermoelectric Power Factor Induced By Topological Phase Transition., Zhi Li, Koushik Pal, Huiju Lee, Chris Wolverton, Yi Xia
Electron-Phonon Interaction Mediated Gigantic Enhancement Of Thermoelectric Power Factor Induced By Topological Phase Transition., Zhi Li, Koushik Pal, Huiju Lee, Chris Wolverton, Yi Xia
Mechanical and Materials Engineering Faculty Publications and Presentations
We propose an effective strategy to significantly enhance the thermoelectric power factor (PF) of a series of 2D semimetals and semiconductors by driving them toward a topological phase transition (TPT). Employing first-principles calculations with an explicit consideration of electron-phonon interactions, we analyze the electronic transport properties of germanene across the TPT by applying hydrogenation and biaxial strain. We reveal that the nontrivial semimetal phase, hydrogenated germanene with 8% biaxial strain, achieves a considerable 4-fold PF enhancement, attributed to the highly asymmetric electronic structure and semimetallic nature of the nontrivial phase. We extend the strategy to another two representative 2D materials …
Inertial Particle Clustering Due To Turbulence In An Air Jet, Bianca Viggiano, Kris Gish, Stephen Solovitz, Raul Bayoan Cal
Inertial Particle Clustering Due To Turbulence In An Air Jet, Bianca Viggiano, Kris Gish, Stephen Solovitz, Raul Bayoan Cal
Mechanical and Materials Engineering Faculty Publications and Presentations
Explosive volcanic eruptions create turbulent plumes of fine ash particles. When these particles collide in the presence of moisture and electrostatic fields they combine into larger aggregates, which can significantly change the atmospheric residence time of the airborne cloud. Previous studies have suggested that turbulence may lead to preferential concentration—also known as clustering—of particles within the flow, increasing the likelihood of collisions and aggregation. Few experimental studies have quantified these processes for volcanic plumes. This behavior was investigated using a particle-laden air jet. By systematically varying the exit speed and the size, density, and concentration of particles, flows were produced …
Machine Learning A Universal Harmonic Interatomic Potential For Predicting Phonons In Crystalline Solids, Huiju Lee, Yi Xia
Machine Learning A Universal Harmonic Interatomic Potential For Predicting Phonons In Crystalline Solids, Huiju Lee, Yi Xia
Mechanical and Materials Engineering Faculty Publications and Presentations
Phonons, as quantized vibrational modes in crystalline materials, play a crucial role in determining a wide range of physical properties, such as thermal and electrical conductivity, making their study a cornerstone in materials science. In this study, we present a simple yet effective strategy for deep learning harmonic phonons in crystalline solids by leveraging existing phonon databases and state-of-the-art machine learning techniques. The key of our method lies in transforming existing phonon datasets, primarily represented in interatomic force constants, into a force-displacement representation suitable for training machine learning universal interatomic potentials. By applying our approach to one of the largest …
Wavelength-Induced Shedding Frequency Modulation Of Seal Whisker Inspired Cylinders, Trevor Dunt, Kirby S. Heck, Kathleen Lyons, Christin Murphy, Raul Bayoan Cal, Jennifer A. Franck
Wavelength-Induced Shedding Frequency Modulation Of Seal Whisker Inspired Cylinders, Trevor Dunt, Kirby S. Heck, Kathleen Lyons, Christin Murphy, Raul Bayoan Cal, Jennifer A. Franck
Mechanical and Materials Engineering Faculty Publications and Presentations
The spanwise undulated cylinder geometry inspired by seal whiskers has been shown to alter shedding frequency and reduce fluid forces significantly compared to smooth cylindrical geometry. Undulation wavelength is systematically investigated in order to explore its effect on unsteady lift force and shedding frequency. Prior research has parameterized the whisker-inspired geometry and demonstrated the relevance of geometric variations on force reduction properties. Among the geometric parameters, undulation wavelength was identified as a significant contributor to forcing changes. To analyze the effect of undulation wavelength, a thorough investigation isolating changes in wavelength is performed to expand upon previous research that parameterized …
Droplet Jump From A Particle Bed, Karl Cardin, Facundo Cabrera-Booman, Raúl Bayoán Cal
Droplet Jump From A Particle Bed, Karl Cardin, Facundo Cabrera-Booman, Raúl Bayoán Cal
Mechanical and Materials Engineering Faculty Publications and Presentations
Drop tower experiments have been performed to study droplet jump from a particle bed across a wide range of fluid viscosities. Here the droplet jumps from the particle bed in response to the apparent step reduction from terrestrial gravity to microgravity when the experiment is dropped and enters free fall. The presence of a particle layer has been found to affect contact line dissipation and the overall jumping behavior of droplets. Additionally, the study has identified the impact of the Ohnesorge number (Oh) on droplet morphology. The investigation has yielded results that not only validate a modified version of the …
Experimental And Modeled Assessment Of Interventions To Reduce Pm2.5 In A Residence During Awildfire Event, Chrissi Argyro Antonopoulos, H. E. Dillon, Elliott T. Gall
Experimental And Modeled Assessment Of Interventions To Reduce Pm2.5 In A Residence During Awildfire Event, Chrissi Argyro Antonopoulos, H. E. Dillon, Elliott T. Gall
Mechanical and Materials Engineering Faculty Publications and Presentations
Increasingly large and frequent wildfires affect air quality even indoors by emitting and dispersing fine/ultrafine particulate matter known to pose health risks to residents. With this health threat, we are working to help the building science community develop simplified tools that may be used to estimate impacts to large numbers of homes based on high-level housing characteristics. In addition to reviewing literature sources, we performed an experiment to evaluate interventions to mitigate degraded indoor air quality. We instrumented one residence for one week during an extreme wildfire event in the Pacific Northwest. Outdoor ambient concentrations of PM2.5 reached historic …
Path Instabilities And Drag In The Settling Of Single Spheres, Facundo Cabrera-Booman, Nicolas Plihon, Mickael Bourgoin
Path Instabilities And Drag In The Settling Of Single Spheres, Facundo Cabrera-Booman, Nicolas Plihon, Mickael Bourgoin
Mechanical and Materials Engineering Faculty Publications and Presentations
The settling behavior of individual spheres in a quiescent fluid was studied experimentally. The dynamics of the spheres was analyzed in the parameter space of particle-to-fluid density ratio (Γ) and Galileo number (Ga), with Γ ∈ (1.1,7.9) and Ga ∈ (100,340). The experimental results showed for the first time that the mean trajectory angle with the vertical exhibits a complex behavior as Ga and Γ are varied. Numerically predicted regimes such as Vertical Periodic for low Γ values, and Planar Rotating for high Γ values were validated. In particular, for the denser spheres, a clear transition from planar to non-planar …