Engineering Commons^™

Modeling Of Signals And Spectra: 5g And Beyond, Xianzhen Yang

Dissertations and Theses

The collection of papers addresses various aspects of spectra and signals in RF wireless systems for 5G and beyond. The first paper focuses on the nonlinear effects of amplified dual-band OFDM signals, providing a spectrum model for intermodulation and cross-modulation. The second paper extends this analysis beyond bandwidth restrictions, enabling accurate prediction of amplified dual-band spectrum. The third paper emphasizes the significance of out-of-band intermodulation products and derives an analytical expression using third-order intercept points. The fourth paper presents a unified spectrum expression for OFDM, FBMC, and F-OFDM, facilitating comparative insights into these signals. The fifth paper explores second-order intermodulation …

Low Internal Air Space In Plants With Crassulacean Acid Metabolism May Be An Anatomical Spandrel, Alistair Leverett, Anne Borland, Emma Inge, Samantha Hartzell

Civil and Environmental Engineering Faculty Publications and Presentations

Crassulacean Acid Metabolism (CAM) is a photosynthetic adaptation found in at least 38 plant families. Typically, the anatomy of CAM plants is characterised by large photosynthetic cells and a low percentage of leaf volume comprised of internal air space (% IAS). It has been suggested that reduced mesophyll conductance (g_m) arising from low % IAS benefits CAM plants by preventing the movement of CO₂ out of cells and ultimately minimising leakage of CO₂ from leaves into the atmosphere during day-time decarboxylation. Here, we propose that low % IAS does not provide any adaptive benefit to …

Phase Stability Of Lead Phosphate Apatite, Jiahong Shen, Dale Gaines Ii, S. Shahabfar, Zi Li, Dohun Kang, Sean Griesemer, Adolfo Salgado-Casanova, Tzu-Chen Liu, Yi Xia, Multiple Additional Authors

Mechanical and Materials Engineering Faculty Publications and Presentations

Recently, Cu-substituted lead apatite LK-₉₉ was reported to have room-temperature ambientpressure superconductivity. Here we utilize density functional theory (DFT) total energy and harmonic phonon calculations to investigate the thermodynamic and dynamic stability of two lead phosphate apatites in their pure and Cu-substituted structures. Though Pb₁₀(PO₄)₆O and Pb₁₀(PO₄)₆(OH)₂ are found to be thermodynamically stable (i.e., on the T=₀K ground state convex hull), their Cu-substituted counterparts are above the convex hull. Harmonic phonon calculations reveal dynamic instabilities in all four of these structures. Oxygen vacancy formation …

A Study On The Gaseous Radionuclide Dispersion In The Highway Across Urban Blocks: Effects Of The Urban Morphology, Roadside Vegetation And Leakage Location, Rui Jia, Jianzhi Yang, Xiaowei Zhu, Fusuo Xu, Liping Wang

Mechanical and Materials Engineering Faculty Publications and Presentations

Spent fuel is a used nuclear waste that poses a great hazard to human body and the environment. In this work, the dispersion of gaseous radionuclides from the highway to downstream urban is simulated using CFD based on a hypothetical spent fuel transport accident, with focus on the effects of urban morphology, roadside vegetation and leakage location. The velocity field, TKE (turbulent kinetic energy) distribution and radionuclide concentration under different conditions are carefully explored. The results show that the dispersion of radionuclides is greatly influenced by the velocity field and TKE distribution. The health risk to the residents of sparse …

Modeling And Validating Temporal Rules With Semantic Petri Net For Digital Twins, Han Liu, Xiaoyu Song, Ge Gao, Hehua Zhang, Yu-Shen Liu, Ming Gu

Electrical and Computer Engineering Faculty Publications and Presentations

Semantic rule checking on RDFS/OWL data has been widely used in the construction industry. At present, semantic rule checking is mainly performed on static models. There are still challenges in integrating temporal models and semantic models for combined rule checking. In this paper, Semantic Petri-Net (SPN) is proposed as a novel temporal modeling and validating method, which implements the states and transitions of the Colored Petri-Net directly based on RDFS and SPARQL, and realizes two-way sharing of knowledge between domain semantic webs and temporal models in the runtime. Several cases are provided to demonstrate the possible applications in digital twins …

Assessing The Performance Of Exchange-Correlation Functionals On Lattice Constants Of Binary Solids At Room Temperature Within The Quasiharmonic Approximation, Xiaofei Shao, Peitao Liu, Cesare Franchini, Yi Xia, Jiangang He

Mechanical and Materials Engineering Faculty Publications and Presentations

The exchange-correlation functional is at the core of density functional theory (DFT) and determines the accuracy of DFT in describing the interactions among electrons/ions in solids and molecules. The strongly constrained and appropriately normed functional (SCAN) and its derivatives, regularized SCAN (rSCAN) and regularized-restored SCAN (r2SCAN), are particularly promising due to their remarkable overall accuracy in the description of various properties while retaining a high computational efficiency as compared to hybrid functionals. However, an exhaustive assessment on the performance of these functionals in predicting the finite-temperature lattice constant of solids is still lacking. Here, we systematically study the room-temperature lattice …

Compensation Of Seeding Bias For Particle Tracking Velocimetry In Turbulent Flows, Thomas Barois, Bianca Viggiano, Thomas Basset, Raúl Bayoán Cal, Romain Volk, Mathieu Gibert, Mickael Bourgoin

Mechanical and Materials Engineering Faculty Publications and Presentations

When a fluid in turbulent motion is tagged by a nonuniform concentration of ideal tracers, the mean velocity of the tracers may not match with the mean velocity of the fluid flow. This implies that conventional particle tracking velocimetry will not produce the mean flow of a turbulent flow unless the particle seeding is homogeneous. In this work, we consider the problem of mean flow estimation from a set of particle tracks obtained in a situation of nonhomogeneous seeding. To compensate the bias caused by the nonhomogeneous particle seeding, we propose a modified particle tracking velocimetry method. This method is …

Systematic Characterization Of Power Side Channel Attacks For Residual And Added Vulnerabilities, Aurelien Tchoupou Mozipo

Dissertations and Theses

Power Side Channel Attacks have continued to be a major threat to cryptographic devices. Hence, it will be useful for designers of cryptographic systems to systematically identify which type of power Side Channel Attacks their designs remain vulnerable to after implementation. It’s also useful to determine which additional vulnerabilities they have exposed their devices to, after the implementation of a countermeasure or a feature. The goal of this research is to develop a characterization of power side channel attacks on different encryption algorithms' implementations to create metrics and methods to evaluate their residual vulnerabilities and added vulnerabilities. This research studies …

Quantifying Uncertainties In Direct-Numerical-Simulation Statistics Due To Wall-Normal Numerics And Grids, Peng E. S. Chen, Xiaowei Zhu, Yipeng Shi, Xiang I. A. Yang

Mechanical and Materials Engineering Faculty Publications and Presentations

This paper takes the perspective of a user of direct-numerical-simulation (DNS) data and quantifies the uncertainties in DNS statistics for plane channel flows. We focus on high-order statistics, such as skewness, kurtosis, and viscous dissipation, and quantify the uncertainties due to wall-normal numerics and grids while minimizing the sampling error and the discretization error in the wall-parallel directions. Two grid distributions and four discretization methods are considered, which are representative of the existing DNSs. Our results show that the available DNS data contain at least a 7% uncertainty in the computed mean viscous dissipation in the buffer layer. Moreover, since …

Load Effects Of Truck Platooning On Existing Bridges In Oregon, Patricia Oleson

Civil and Environmental Engineering Master's Project Reports

Truck Platooning (TP) involves managing multiple trucks closely together to reduce aerodynamic drag. While TP offers benefits such as fuel savings, emission reductions, and enhanced safety, it raises concerns for existing infrastructure. This study reviews literature on TP and conducts bridge analyses comparing representative truck platoon configurations allowed under Oregon law with current truck loadings. It also explores the effects of truck head spacing and bridge span lengths, utilizing the research results to calculate rating factors using real-world case studies. The objective is to identify truck platoon configurations that may exceed acceptable load levels for Oregon bridges. The findings will …

Modeling Cyanotoxin Production, Fate, And Transport In Surface Water Bodies Using Ce-Qual-W2, Bernadel Rose Hintz Garstecki, Scott A. Wells

Civil and Environmental Engineering Faculty Publications and Presentations

Cyanobacteria are frequently associated with forming toxic blooms. The toxins produced by cyanobacteria, cyanotoxins, are harmful to both humans and animals. Rising temperatures due to global climate change are expected to increase the occurrence of cyanobacteria, and it is vital that we protect our drinking water supplies and natural water resources. Modeling the production, fate, and transport of these toxins is an important step in limiting exposure to them and evaluating management strategies to mitigate their impact. The research provided here offers an overview of some of the main cyanotoxins of concern and presents preliminary models for the transport and …

Distributed Deep Learning Optimization Of Heat Equation Inverse Problem Solvers, Zhuowei Wang, Le Yang, Haoran Lin, Genping Zhao, Zixuan Liu, Xiaoyu Song

Electrical and Computer Engineering Faculty Publications and Presentations

The inversion problem of partial differential equation plays a crucial role in cyber-physical systems applications. This paper presents a novel deep learning optimization approach to constructing a solver of heat equation inversion. To improve the computational efficiency in large-scale industrial applications, data and model parallelisms are incorporated on a platform of multiple GPUs. The advanced Ring-AllReduce architecture is harnessed to achieve an acceleration ratio of 3.46. Then a new multi-GPUs distributed optimization method GradReduce is proposed based on Ring-AllReduce architecture. This method optimizes the original data communication mechanism based on mechanical time and frequency by introducing the gradient transmission scheme …

Lift Force Analysis For An Electrodynamic Wheel Maglev Vehicle, Colton W. Bruce, Jonathan Bird, Matthew K. Grubbs

Electrical and Computer Engineering Faculty Publications and Presentations

This paper used an analytic based 3-D second order vector potential model to study the vertical dynamic force ripple and dynamic airgap height change when using a one pole-pair electrodynamic wheel (EDW) maglev vehicle. A one-pole pair EDW creates the lowest lift specific power; however transient finite element analysis (FEA) also shows that the one pole-pair EDW will create a large oscillating vertical force when maintaining a static airgap height. A dynamically coupled eddy current model was used to confirm that when the airgap length is allowed to change with time then an increase in vertical airgap creates a large …

Cu2o Heterojunction Solar Cell With Photovoltaic Properties Enhanced By A Ti Buffer Layer, Binghao Wang, Zhiqiang Chen, Feng Zhao

Center for Electron Microscopy and Nanofabrication Publications and Presentations

In this study, semiconductor oxide cuprite (Cu2O) and indium tin oxide (ITO) heterojunction solar cells with and without a 10 nm thick titanium (Ti) thin film as the buffer layer were fabricated and characterized for comparison. The Cu2O film was formed by low-cost electrodeposition, and Ti and ITO layers were deposited on a glass substrate by sputtering. The interfacial microstructures, surface topology, and electrical and photovoltaic properties of both solar cells were investigated. The test results showed that the Ti buffer layer changed the surface morphology, resistivity, and contact potential of the electrodeposited Cu2O film. With these changes, the photovoltaic …

Developing And Testing Low-Cost Air Cleaners For Safer Spaces During Wildfires, Brett William Stinson

Dissertations and Theses

Air cleaning reduces indoor exposure to fine particulate matter (PM_2.5) during wildfire events. However, resource and cost restraints may limit access to air cleaning during such an event, as both commercial devices and the high-rated MERV filters that homemade assemblies typically rely upon tend to be expensive and in short supply. With these barriers in mind, we sought to develop and evaluate the potential for air cleaners that use common household fabrics as filtration media. Evaluated designs use a box fan to move air across fabric filters; box fans are inexpensive and readily available to many households. Ultimately, …

Consumer 3d Printing For Remote Control Aircraft Wings: Development Of Novel Wingbox Structure, Ian Clark

University Honors Theses

Remote control aircraft construction and can be a very expensive and time-consuming hobby. With 3D printer consumer adoption rates skyrocketing, there is a gap between demand for RC aircraft and suitable well-designed models available to creators and hobbyists. By creating and testing two iterations of wingbox geometries, this research aims to help close that gap by producing an easily printable wing structure. While there are improvements that can be made on this work, this research has been effective in generating a novel wingbox structure for FFF 3D printing that has distinct advantages over other designs currently available.

Uncovering Transient Dynamics And Equilibrium States Of Particle Aggregates With RaúL BayoáN Cal, RaúL BayoáN Cal

PDXPLORES Podcast

In this episode of PDXPLORES, Raúl Bayoán Cal, Professor of Mechanical & Materials Engineering at the Maseeh College of Engineering and Computer Science, discusses his latest National Science Foundation award-winning research, Uncovering Transient Dynamics and Equilibrium States of Particle Aggregates in Fluids, investigating transient dynamics of fluid mechanics in the absence of gravity. These experiments, which utilize the Dryden Drop Tower and research facilities aboard the International Space Station, will benefit the study of granular media in aggregation models such as pollen deposition, algae growth, and plastic pollution.

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Hybrid Photovoltaic + Battery Energy System Grid-Tied Converter Capstone Review Thesis, Archer Taylor

University Honors Theses

Hybrid power converters present an opportunity to more efficiently harness energy from renewable sources. This paper reviews an undergraduate senior capstone project with the goal of designing and verifying the benefits of a hybrid converter, combining a photovoltaic array, battery energy system and a DC-AC inverter. The author recounts their experience throughout the 6 month period, detailing the research and design process followed by the prototype testing. Additionally, they reflect on the struggles of the capstone team and how to apply the learnings in the future.

Evaluation Of Metaverse Traffic Safety Implementations Using Fuzzy Einstein Based Logarithmic Methodology Of Additive Weights And Topsis Method, Muhammet Deveci, Dragan Pamucar, Ilgin Gokasar, Mario Köppen, Brij B. Gupta, Tugrul Daim

Engineering and Technology Management Faculty Publications and Presentations

As the Metaverse’s popularity grows, its effect on everyday problems is beginning to be discussed. The upcoming Metaverse world will influence the transportation system as cross-border lines blur due to rapid globalization. The purpose of this paper is to investigate the capabilities of the Metaverse and its alternatives to traffic safety, as well as to prioritize its advantages. The case study is based on a densely populated metropolis with an extensive education system. The city’s decision-makers will have to weigh the pros and cons of the Metaverse’s effect on traffic safety. To illustrate the complex forces that drive the decision-making …

Impacts Of A Cascadia Subduction Zone Earthquake On Water Levels And Wetlands Of The Lower Columbia River And Estuary, M. W. Brand, Heida Diefenderfer, J. E. O’Connor, Amy B. Borde, D. A. Jay, Aqeel Al-Bahadily, M. Mckeon, S. A. Talke

Civil and Environmental Engineering Faculty Publications and Presentations

Subsidence after a subduction zone earthquake can cause major changes in estuarine bathymetry. Here, we quantify the impacts of earthquake-induced subsidence on hydrodynamics and habitat distributions in a major system, the lower Columbia River Estuary, using a hydrodynamic and habitat model. Model results indicate that coseismic subsidence increases tidal range, with the smallest changes at the coast and a maximum increase of ∼10% in a region of topographic convergence. All modeled scenarios reduce intertidal habitat by 24%–25% and shifts ∼93% of estuarine wetlands to lower-elevation habitat bands. Incorporating dynamic effects of tidal change from subsidence yields higher estimates of remaining …

Data From: Shallow-Water Habitat In The Lower Columbia River Estuary: A Highly Altered System, Will Templeton, David Jay, Heida Diefenderfer, S. A. Talke

Civil and Environmental Engineering Faculty Datasets

This is the dataset to accompany the article, Shallow-Water Habitat in the Lower Columbia River Estuary: A Highly Altered System [Data set], accepted for publication in Estuaries and Coasts.

OVERVIEW OF THE SUPPLEMENTAL DATA FILES:

The files include water level data for 26 locations across varying time frames, as described below, and Columbia and Willamette River discharge measurements and estimates for observed, naturalized, and adjusted flows.

All water levels:

1. All water levels are reported as six-minute interpolated water level records derived from measured water levels. 2. The first column is date-time with date and time separated by a …

Evaluation Of The Alternatives Of Introducing Electric Vehicles In Developing Countries Using Type-2 Neutrosophic Numbers Based Rafsi Model, Ilgin Gokasar, Muhammet Deveci, Mehtap Isik, Tugrul Daim, Aws A. Zaidan, Florentin Smarandache

Engineering and Technology Management Faculty Publications and Presentations

This study focuses on implementing electric vehicles (EVs) in developing countries where energy production is mainly based on fossil fuels. Although for these countries the environmental short-run benefits of the EVs cannot offset the short-run costs, it may still be the best option to implement the EVs as soon as possible. Hence, it is necessary to evaluate the alternatives to introducing EVs to the market due to the environmental concerns that created an opportunity for some developing countries to catch up with the international competition. Therefore, we develop a case scenario to explore the decision-making process in implementing the EVs …

Gas Metal Arc Welding With Undermatched Filler Wire For Hot-Press-Formed Steel Of 2.0 Gpa Strength: Influence Of Filler Wire Strength And Bead Geometry, Dong-Yoon Kim, Cheolhee Kim, Tae Hyen Lee, Minjung Kang, Junhong Park

Mechanical and Materials Engineering Faculty Publications and Presentations

Commercial welding filler wires have less strength than hot-press-forming (HPF) steels. As the 2.0 GPa-HPF steel sheets have been released, their lap welding characteristics were investigated using gas metal arc welding in this study. The base metal was 1.1 mm-thick 2.0 GPa-HPF steel sheets, and three filler metal wires considered in this study (W540, W920, and W980) had tensile strengths of 540, 920, and 980 MPa, respectively. Gas metal arc welding was performed under a controlled short-circuit mode, and the wire feed speed (WFS) was selected as a process parameter. Tensile-shear test and microscopy were performed to evaluate the joint …

Spheroidization Heat Treatment Conditions With Data Analysis In Medium Carbon Cr-Mo Steel For Ultra High Strength Cold Heading, Yong Deok Jo, Sung Yi, Byoung Lok Jang

Mechanical and Materials Engineering Faculty Publications and Presentations

The degree to which parameters affect the spheroidization heat treatment of steel was calculated by setting the spheroidization heat treatment conditions of Cr-Mo steel and using data analysis such as S/N ratio and ANOVA. After analyzing the transformation temperatures of the steel, A_c1 and A_c3, using a DSC, the conditions were set accordingly. The surface hardness was measured for the conditions and used as an evaluation index. The correlation was analyzed by comparing the spheroidized volume fraction and the surface hardness, and the Pearson correlation coefficient was -0.88, proving that a correlation existed between the two values. …

Measurement Of Polycyclic Aromatic Hydrocarbons (Pahs) On Indoor Materials: Method Development, Aurélie Laguerre, Elliott T. Gall

Mechanical and Materials Engineering Faculty Publications and Presentations

Wildfire smoke penetrates indoors, and polycyclic aromatic hydrocarbons (PAHs) in smoke may accumulate on indoor materials. We developed two approaches for measuring PAHs on common indoor materials: (1) solvent-soaked wiping of solid materials (glass and drywall) and (2) direct extraction of porous/fleecy materials (mechanical air filter media and cotton sheets). Samples are extracted by sonication in dichloromethane and analyzed with gas chromatography–mass spectrometry. Extraction recoveries range from 50–83% for surrogate standards and for PAHs recovered from direct application to isopropanol-soaked wipes, in line with prior studies. We evaluate our methods with a total recovery metric, defined as the sampling and …

The Role Of High-Order Anharmonicity And Off-Diagonal Terms In Thermal Conductivity: A Case Study Of Multi-Phase Cspbbr3, Xiangdong Ding, Guimei Zhu, Yi Xia, Jie Ren, Jun Sun, Multiple Additional Authors

Mechanical and Materials Engineering Faculty Publications and Presentations

We investigate the influence of three- and four-phonon scattering, perturbative anharmonic phonon renormalization, and off-diagonal terms of coherent phonons on the thermal conductivity of CsPbBr3 phase change perovskite, by using advanced implementations and first-principles simulations. Our study spans a wide temperature range covering the entire structural spectrum. Notably, we demonstrate that the interactions between acoustic and optical phonons result in contrasting trends of phonon frequency shifts for the high-lying optical phonons in orthorhombic and cubic CsPbBr3 as temperature varies. Our findings highlight the significance of wavelike tunneling of coherent phonons in ultralow and glasslike thermal conductivity in halide perovskites.

Residual Vulnerabilities To Power Side Channel Attacks Of Lightweight Ciphers Cryptography Competition Finalists, Aurelien Mozipo, John M. Acken

Electrical and Computer Engineering Faculty Publications and Presentations

The protection of communications between Internet of Things (IoT) devices is of great concern because the information exchanged contains vital sensitive data. Malicious agents seek to exploit those data to extract secret information about the owners or the system. Power side channel attacks are of great concern on these devices because their power consumption unintentionally leaks information correlatable to the device's secret data. Several studies have demonstrated the effectiveness of authenticated encryption with advanced data, in protecting communications with these devices. A comprehensive evaluation of the seven (out of 10) algorithm finalists of the National Institute of Standards and Technology …

An Examination Of The Stiffness Terms Needed To Model The Dynamics Of An Eddy Current Based Maglev Vehicle, Colton W. Bruce, Jonathan Bird

Electrical and Computer Engineering Faculty Publications and Presentations

This paper re-examines the basis for each eddy current stiffness term computed from prior published steady-state eddy current models. The paper corrects prior analysis work by confirming, through the use of 2-D and 3-D dynamic finite element analysis modelling, that when a magnetic source is moving over an infinite-wide and infinite-long conductive sheet guideway the steady-state lateral and translational stiffness terms will be zero and only the vertical coupled stiffness terms need to be modelled. Using these observations, a much simplified 6 degrees-of-freedom (DoF) linearized eddy current dynamic force model can be used to compute the steady-state force changes in …

A Hierarchical Decision Model To Evaluate Healthcare Organization's Readiness To Implement Clinical Decision Support Systems, Mohammed Oussama Laraichi

Dissertations and Theses

Clinical Decision Support Systems (CDSS) are essential tools for healthcare organizations as well as for healthcare providers to improve clinical care. However, successful implementation of CDSS can be challenging. Therefore, before implementing CDSS, it is crucial to assess the readiness of healthcare organizations to implement these tools.

Through a literature review, the first step of this research explores the concept of clinical decision support and CDSS, discussing their features, characteristics, and organizational hurdles to implementation. It also provides perspectives on CDSS adoption in the context of Information Systems and Health Technology. The review helped identify research gaps, objectives, and questions. …

Anomalous Lattice Thermal Conductivity Driven By All-Scale Electron-Phonon Scattering In Bulk Semiconductors, Z. Z. Zhou, Y. C. Yan, X. L. Yang, Yi Xia, G. Y. Wang, X. Lu, X. Y. Zhou

Mechanical and Materials Engineering Faculty Publications and Presentations

Electron-phonon coupling (EPC) has been broadly considered to govern the charge transport in solids, whereas its effect on thermal conductivity, especially for semiconductors at ambient temperatures, is a widely debated issue in condensed-matter physics. Employing state-of-the-art first-principles calculations to quantify all the possible scattering factors, we show the dominant role of EPC in phonon transport of n-doped GaSb, which yields an unprecedented reduction of lattice thermal conductivity and triggers anomalous temperature-independent behavior. The significant EPC impact hinges on the joint effect of multiple conduction pockets, large EPC strength, and bunched heat-carrying acoustic branches, provoking strong electron-phonon scattering to surpass the …