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2023

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Articles 8611 - 8640 of 9777

Full-Text Articles in Engineering

Reduction Of Iron-Ore Pellets Using Different Gas Mixtures And Temperatures, Yuri Korobeinikov, Amogh Meshram, Christopher Harris, Olexandr Kovtun, Joe Govro, Ronald J. O'Malley, Olena Volkova, Seetharaman Sridhar Jan 2023

Reduction Of Iron-Ore Pellets Using Different Gas Mixtures And Temperatures, Yuri Korobeinikov, Amogh Meshram, Christopher Harris, Olexandr Kovtun, Joe Govro, Ronald J. O'Malley, Olena Volkova, Seetharaman Sridhar

Materials Science and Engineering Faculty Research & Creative Works

Direct reduction of iron ore (DRI) is gaining an increased attention due to the growing need to decarbonize industrial processes. The current industrial DRI processes are performed using reformed natural gas, which results in CO2 emission, although it is less than carbothermic reduction in the blast furnace. Carbon-free reduction may be realized through the utilization of green H2 as a reducing agent, in place of natural gas. Herein, the effects of various gas mixtures and temperature on the reduction kinetics of the hematite iron-ore pellets are focused on in this work. Pellets are reduced at 700, 800, 850, …

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Additive Manufacturing Of (Mgconicuzn)O High-Entropy Oxide Using A 3d Extrusion Technique And Oxide Precursors, Ruoyu Chen, Saisai Li, Qingfeng Yan, Haiming Wen Jan 2023

Additive Manufacturing Of (Mgconicuzn)O High-Entropy Oxide Using A 3d Extrusion Technique And Oxide Precursors, Ruoyu Chen, Saisai Li, Qingfeng Yan, Haiming Wen

Materials Science and Engineering Faculty Research & Creative Works

This report presents an additive manufacturing approach, for the first time, to producing high-entropy oxides (HEOs) using a 3D extrusion-based technique with oxide precursors. The precursors were prepared by a wet chemical method from sulfates. Additives were utilized to optimize the rheological properties of the printing inks with these precursors, and the properties of the printed HEOs were improved by increasing the solid content of the inks. When ink with a solid content of 78 wt% was used for printing, the resulting HEO exhibited a relative density of 92% and a high dielectric constant after undergoing pressure less sintering at …

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The Effect Of Crystal Anisotropy On Fracture Toughness And Strength Of Zrb2 Microcantilevers, Tamás Csanádi, Ahmad Azizpour, Marek Vojtko, William Fahrenholtz Jan 2023

The Effect Of Crystal Anisotropy On Fracture Toughness And Strength Of Zrb2 Microcantilevers, Tamás Csanádi, Ahmad Azizpour, Marek Vojtko, William Fahrenholtz

Materials Science and Engineering Faculty Research & Creative Works

The influence of crystal anisotropy on the micromechanical properties of ceramic grains plays an important role in the design of the macromechanical performance of bulk polycrystalline samples. To this end, the effect of crystal orientation on fracture toughness and strength was investigated by microcantilever bending experiments combined with finite element method (FEM) simulations in grains of a polycrystalline ZrB2 sample. The sample was prepared by hot pressing and the crystal orientations were determined by electron backscatter diffraction after careful surface preparation. The bending tests were carried out on notched and unnotched microcantilevers cut from specific grains along the prismatic (⊥ …

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In Situ And Real-Time Mold Flux Analysis Using A High-Temperature Fiber-Optic Raman Sensor For Steel Manufacturing Applications, Bohong Zhang, Hanok Tekle, Ronald J. O'Malley, Todd Sander, Jeffrey D. Smith, Rex E. Gerald, Jie Huang Jan 2023

In Situ And Real-Time Mold Flux Analysis Using A High-Temperature Fiber-Optic Raman Sensor For Steel Manufacturing Applications, Bohong Zhang, Hanok Tekle, Ronald J. O'Malley, Todd Sander, Jeffrey D. Smith, Rex E. Gerald, Jie Huang

Materials Science and Engineering Faculty Research & Creative Works

Continuous Casting in Steel Production Uses Specially Developed Oxyfluoride Glasses (Mold Fluxes) to Lubricate a Mold and Control the Solidification of the Steel in the Mold. the Composition of the Flux Impacts Properties, Including Basicity, Viscosity, and Crystallization Rate, All of Which Affect the Stability of the Casting Process and the Quality of the Solidified Steel. However, Mold Fluxes Interact with Steel during the Casting Process, Resulting in Flux Chemistry Changes that Must Be Considered in the Flux Design. Currently, the Chemical Composition of Mold Flux Must Be Determined by Extracting Flux Samples from the Mold during Casting and Then …

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In Situ High-Temperature Raman Spectroscopy Via A Remote Fiber-Optic Raman Probe, Bohong Zhang, Hanok Tekle, Ronald J. O'Malley, Jeffrey D. Smith, Rex E. Gerald, Jie Huang Jan 2023

In Situ High-Temperature Raman Spectroscopy Via A Remote Fiber-Optic Raman Probe, Bohong Zhang, Hanok Tekle, Ronald J. O'Malley, Jeffrey D. Smith, Rex E. Gerald, Jie Huang

Materials Science and Engineering Faculty Research & Creative Works

This Study Demonstrated for the First Time an in Situ High-Temperature Fiber-Optic Raman Probe to Study the Structure of Glass and Slag Samples at Temperatures Up to 1400 °C. a Customized External Telescope Was Integrated into a Portable Fiber-Optic Raman Probe to Extend the Optical Working Distance to Allow the Probe to Work in a High-Temperature Environment. Three Samples Were Evaluated to Demonstrate the Functionality of the High-Temperature Fiber-Optic Raman Probe. Room Temperature and High-Temperature Raman Spectra Were Successfully Collected and Analyzed. in Addition, a Deconvolution Algorithm Was Used to Identify Peaks in the Spectrum that Could Then Be Related …

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Compositional Modifications To Alter And Suppress Laves Phases In Alxcrmotayti Alloys, Austin E. Mann, Joseph William Newkirk Jan 2023

Compositional Modifications To Alter And Suppress Laves Phases In Alxcrmotayti Alloys, Austin E. Mann, Joseph William Newkirk

Materials Science and Engineering Faculty Research & Creative Works

Herein, the Development of Refractory Complex Concentrated Alloys in the Al–Cr–Mo–Ta–Ti Alloy System is Reported. Alloys with Modified Al and Ta Concentrations Are Designed using CALPHAD Tools and Produced Via Arc Melting and Characterized in Both As-Cast and Annealed Forms. Properties of the Alloys, Nature of the Microstructures, and Phase Transformation Behavior Are Described Via X-Ray Diffraction, Microstructural Characterization, Microhardness, and Differential Scanning Calorimetry. Two Alloys, Namely, Al0.25CrMoTa0.8Ti and Al0.75CrMoTa0.8Ti, Are Represented by a Body-Centered-Cubic Matrix Phase after Annealing, along with a Secondary Cr–Ta Laves Phase of the C15 and C14 Polytypes, respectively. in As-Cast and Annealed Forms, the Al0.75CrMoTa0.45Ti …

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High Temperature Dielectric Properties Of Calcium Zirconate, Alan Devoe, Hung Trinh, Fatih Dogan Jan 2023

High Temperature Dielectric Properties Of Calcium Zirconate, Alan Devoe, Hung Trinh, Fatih Dogan

Materials Science and Engineering Faculty Research & Creative Works

The electrical properties of dense, high purity CaZrO3 discs, sintered at 1380°C with and without added ZrO2, were investigated up to 950°C. Dielectric constant, loss tangent, and electrical conductivity were measured from 25 to 725°C, and the real and imaginary impedances were measured between 800 and 950°C by impedance spectroscopy techniques. Dielectric constant increased by 8% above 300°C and loss tangent increased from.1% at 25°C to ∼2% above 300°C. Activation energy of electrical conductivity determined between 300°C and 950°C by alternative current (AC) and direct current (DC) measurements. These results indicate that CaZrO3 could be a useful dielectric material for …

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Oxidation Behavior Of Nb-Coated Zirconium Diboride, Jan E. Förster, William Fahrenholtz, Gregory E. Hilmas, Ravisankar Naraparaju Jan 2023

Oxidation Behavior Of Nb-Coated Zirconium Diboride, Jan E. Förster, William Fahrenholtz, Gregory E. Hilmas, Ravisankar Naraparaju

Materials Science and Engineering Faculty Research & Creative Works

Metallic Nb-Coatings Were Deposited on Top of ZrB2 by Means of Magnetron Sputtering to Improve its Oxidation Resistance. High Temperature Oxidation Tests Have Revealed that the Metallic Nb-Coatings Lead to the Formation of a Dense Solid and Protective Reaction Zone in Addition to a More Stable B2O3 Liquid Solution at the Surface. Compared to Baseline ZrB2, a Reduction in the Oxidation Kinetics, as Well as the Thickness of the Porous Zirconia Layer by 71%, Has Been Achieved with the Help of Nb-Coatings. a Liquid Phase Sintering by Molten Nb2O5 Mechanism Was …

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High Temperature Confocal Scanning Laser Microscopy Analysis Of Dead-Burned Magnesia Aggregates, Tyler Richards, Viraj Athavale, Jeffrey D. Smith, Ronald J. O'Malley Jan 2023

High Temperature Confocal Scanning Laser Microscopy Analysis Of Dead-Burned Magnesia Aggregates, Tyler Richards, Viraj Athavale, Jeffrey D. Smith, Ronald J. O'Malley

Materials Science and Engineering Faculty Research & Creative Works

Dead-Burned Magnesia is a Commonly Used Material in the Manufacturing of Refractories for the Steelmaking Industry. Aggregates of Dead-Burned Magnesia Contain Secondary Phases Due to the Impurities within the Magnesite Rock Used in its Production. While These Phases Can Aid in Sintering Magnesia, They May Have Some Impact on the High-Temperature Performance of the Refractory Product. High-Temperature Confocal Scanning Laser Microscopy Was Utilized to Observe the Behavior of Dead-Burned Magnesia Aggregates at Elevated Temperatures (Up to 1550°C). Liquid Formation Was Detected Even at Temperatures Below 1350°C. in Some Cases, This Liquid Quickly Exuded from the Aggregate Surface. This Liquid Phase …

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Intragranular Nanocomposite Powders As Building Blocks For Ceramic Nanocomposites, Ryan D. Dempsey, Xiaoqing He, Jonathan A. Scott, David W. Lipke Jan 2023

Intragranular Nanocomposite Powders As Building Blocks For Ceramic Nanocomposites, Ryan D. Dempsey, Xiaoqing He, Jonathan A. Scott, David W. Lipke

Materials Science and Engineering Faculty Research & Creative Works

A powder-based bottom-up processing scheme is introduced for the production of ceramic nanocomposites. Internal displacement reactions between solid solution powders and metallic reactants proceeding via gaseous intermediates are utilized to generate nanostructured building blocks for the synthesis of ceramic nanocomposites. Subsequent rapid sintering results in ceramic nanocomposites, whose microstructures are inherited from the building blocks. This processing scheme is demonstrated for the production of titanium carbide nanocomposites featuring up to 28 wt.% intragranular tungsten inclusions derived from titanium-tungsten mixed carbide powders. Heat treatment of mixed carbide powders in evacuated ampoules containing titanium sponge and iodine at 1000°C for 24 h …

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Active Church Auditorium Redesign And Renovation, Jonah S. Kim Jan 2023

Active Church Auditorium Redesign And Renovation, Jonah S. Kim

Construction Management

Active Church is a life-giving and dynamic church that exists to move people from where they are to where God wants them to be. This church for most of its lifespan has been located at the Fremont Theater as they did not have a building that they owned. However, in 2022 the church closed escrow on a building that was owned by another church located at 3172 Johnson Ave, San Luis Obispo, 93401. Before moving into the building major renovations needed to be done as this was a very old building from the 1960s. The initial design of the auditorium …

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Thermal And Electrical Properties Of Spark Plasma Sintered (Ti,Cr)B2 Ceramics, Steven M. Smith, Lun Feng, William Fahrenholtz, Gregory E. Hilmas, Laura Silvestroni Jan 2023

Thermal And Electrical Properties Of Spark Plasma Sintered (Ti,Cr)B2 Ceramics, Steven M. Smith, Lun Feng, William Fahrenholtz, Gregory E. Hilmas, Laura Silvestroni

Materials Science and Engineering Faculty Research & Creative Works

Thermal and electrical properties were measured for TiB2 ceramics containing varying CrB2 contents up to 33 mol%. The room-temperature thermal diffusivity decreased with increasing Cr content from 0.330 ± 0.003 cm2/s for pure TiB2 to 0.060 ± 0.003 cm2/s for (Ti0.66Cr0.33)B2. The amount of anisotropy in the coefficients of thermal expansion increased with increasing Cr content and the c-axis had the greatest dependence on Cr addition, with an increase of more than 25% in the thermal expansion for 33 mol% CrB2 compared to TiB2, whereas the a-axis only increased by about 8%. The electrical conductivity was the lowest for (Ti0.66Cr0.33)B2 …

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Characterization Of Virgin, Re-Used, And Oxygen-Reduced Copper Powders Processed By The Plasma Spheroidization Process, M. Hossein Sehhat, David Perez-Palomino, Connor Wiedemeier, Tristan Cullom, Joseph William Newkirk Jan 2023

Characterization Of Virgin, Re-Used, And Oxygen-Reduced Copper Powders Processed By The Plasma Spheroidization Process, M. Hossein Sehhat, David Perez-Palomino, Connor Wiedemeier, Tristan Cullom, Joseph William Newkirk

Materials Science and Engineering Faculty Research & Creative Works

Fabrication of parts with high mechanical properties heavily depend on the quality of powder deployed in the fabrication process. Copper powder in three different powder types were spheroidized using radio-frequency inductively coupled plasma (ICP) spheroidization process (TekSphero-15 system). The characterized powders include virgin powder as purchased from the powder manufacturer, powder used in electron beam powder bed fusion (EB-PBF) process, and reconditioned powder, which was used powder that underwent an oxygen-reduction treatment. The goal of spheroidizing these powder types was to evaluate the change in powder morphology, the possibility of enhancing the powder properties back to their as-received conditions, and …

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Boro/Carbothermal Reduction Co-Synthesis Of Dual-Phase High-Entropy Boride-Carbide Ceramics, Lun Feng, William Fahrenholtz, Gregory E. Hilmas, Stefano Curtarolo Jan 2023

Boro/Carbothermal Reduction Co-Synthesis Of Dual-Phase High-Entropy Boride-Carbide Ceramics, Lun Feng, William Fahrenholtz, Gregory E. Hilmas, Stefano Curtarolo

Materials Science and Engineering Faculty Research & Creative Works

Dense, dual-phase (Cr,Hf,Nb,Ta,Ti,Zr)B2-(Cr,Hf,Nb,Ta,Ti,Zr)C ceramics were synthesized by boro/carbothermal reduction of oxides and densified by spark plasma sintering. The high-entropy carbide content was about 14.5 wt%. Grain growth was suppressed by the pinning effect of the two-phase ceramic, which resulted in average grain sizes of 2.7 ± 1.3 µm for the high-entropy boride phase and 1.6 ± 0.7 µm for the high-entropy carbide phase. Vickers hardness values increased from 25.2 ± 1.1 GPa for an indentation load of 9.81 N to 38.9 ± 2.5 GPa for an indentation load of 0.49 N due to the indentation size effect. Boro/carbothermal …

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Thermal And Electrical Properties Of Spark Plasma Sintered (Ti,Cr)B2 Ceramics, Steven M. Smith, Lun Feng, William Fahrenholtz, Gregory E. Hilmas, Laura Silvestroni Jan 2023

Thermal And Electrical Properties Of Spark Plasma Sintered (Ti,Cr)B2 Ceramics, Steven M. Smith, Lun Feng, William Fahrenholtz, Gregory E. Hilmas, Laura Silvestroni

Materials Science and Engineering Faculty Research & Creative Works

Thermal and electrical properties were measured for TiB2 ceramics containing varying CrB2 contents up to 33 mol%. The room-temperature thermal diffusivity decreased with increasing Cr content from 0.330 ± 0.003 cm2/s for pure TiB2 to 0.060 ± 0.003 cm2/s for (Ti0.66Cr0.33)B2. The amount of anisotropy in the coefficients of thermal expansion increased with increasing Cr content and the c-axis had the greatest dependence on Cr addition, with an increase of more than 25% in the thermal expansion for 33 mol% CrB2 compared to TiB2, whereas the …

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Characterization Of Virgin, Re-Used, And Oxygen-Reduced Copper Powders Processed By The Plasma Spheroidization Process, M. Hossein Sehhat, David Perez-Palomino, Connor Wiedemeier, Tristan Cullom, Joseph William Newkirk Jan 2023

Characterization Of Virgin, Re-Used, And Oxygen-Reduced Copper Powders Processed By The Plasma Spheroidization Process, M. Hossein Sehhat, David Perez-Palomino, Connor Wiedemeier, Tristan Cullom, Joseph William Newkirk

Materials Science and Engineering Faculty Research & Creative Works

Fabrication of parts with high mechanical properties heavily depend on the quality of powder deployed in the fabrication process. Copper powder in three different powder types were spheroidized using radio-frequency inductively coupled plasma (ICP) spheroidization process (TekSphero-15 system). The characterized powders include virgin powder as purchased from the powder manufacturer, powder used in electron beam powder bed fusion (EB-PBF) process, and reconditioned powder, which was used powder that underwent an oxygen-reduction treatment. The goal of spheroidizing these powder types was to evaluate the change in powder morphology, the possibility of enhancing the powder properties back to their as-received conditions, and …

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Microstructure And Residual Stress In Functionally Graded 316l Stainless Steel/Inconel 625 Alloys Fabricated By Direct Energy Deposition, Xinchang Zhang, Liang Wang, Frank W. Liou, Yang Ren, Cheng Sun Jan 2023

Microstructure And Residual Stress In Functionally Graded 316l Stainless Steel/Inconel 625 Alloys Fabricated By Direct Energy Deposition, Xinchang Zhang, Liang Wang, Frank W. Liou, Yang Ren, Cheng Sun

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Functionally graded materials (FGMs) provide a unique solution to combine distinct properties within a single component to enhance its overall performance. Understanding the microstructure and residual stress distribution is particularly important as the material dissimilarity in FGMs can result in high residual stress that affects the mechanical integrity of structural components. This work aims to study the microstructure and residual stress of additively manufactured FGMs and the effects of isothermal annealing. In this study, 316L stainless steel/Inconel 625 FGMs were built by direct energy deposition and characterized by optical and electron microscopy as well as synchrotron-based X-ray diffraction. Our study …

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Charging Of Irregularly-Shaped Dust Grains Near Surfaces In Space, David Lund, Xiaoming He, Daoru Han Jan 2023

Charging Of Irregularly-Shaped Dust Grains Near Surfaces In Space, David Lund, Xiaoming He, Daoru Han

Mathematics and Statistics Faculty Research & Creative Works

This paper presents fully kinetic numerical investigation of the charging of dust grains in low temperature collision less plasmas (stationary) and collision less, cold-ion thermal-electron drifting plasmas. the Parallel Immersed-Finite-Element Particle-in-Cell (PIFE-PIC) code is utilized to self-consistently resolve the plasma environment and charging of immersed materials. This model explicitly includes the materials property (dielectric constant) of dust grains. Effects of materials property, inter-dust distance, and plasma conditions (stationery and drifting) will be investigated for both single-dust and multi-dust configurations.

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A Data-Driven Approach To Multiresolution Analysis Of Near-Field Scanning, Yanming Zhang, Lijun Jiang Jan 2023

A Data-Driven Approach To Multiresolution Analysis Of Near-Field Scanning, Yanming Zhang, Lijun Jiang

Electrical and Computer Engineering Faculty Research & Creative Works

Near-field scanning has been widely adopted as a valuable tool in diagnosing electromagnetic compatibility (EMC) and electromagnetic interference (EMI) problems. This paper proposes a multiresolution dynamic mode decomposition (MRDMD)-based method for analyzing time-varying near-field radiation. MRDMD executes the traditional DMD method recursively and hierarchically. The distribution of DMD eigenvalues determines the slow and fast modes in a level's decomposition, in which the slow modes are reserved, and the fast modes are utilized to generate the input data for the next level. Finally, the multiresolution time-frequency representation of the near-field radiation field is obtained. And the spatial distributions corresponding to each …

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Interval Analysis Method For The Uncertainty And Sensitivity Characterization In Transmission Line Systems, Ping Yuan, Lijun Jiang Jan 2023

Interval Analysis Method For The Uncertainty And Sensitivity Characterization In Transmission Line Systems, Ping Yuan, Lijun Jiang

Electrical and Computer Engineering Faculty Research & Creative Works

Uncertainty in electronic fabrication process could cause serious yield issues and stability concerns. Hence, identifying the resultant range caused by the uncertainty in the system is a critical topic in modern EDA design process. Monte Carlo method is considered as a golden standard but with many drawbacks. In the paper, we propose to use the interval analysis (IA) to analyze the signal integrity and power integrity problems in transmission line (TL) systems. Using the interval representing the uncertainty range of parameters in the system, the uncertainty range of the system can be derived by the derived analytical expression. It is …

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Nanobubble-Induced Aggregation Of Ultrafine Particles: A Molecular Dynamics Study, Eric Bird, Zhi Liang Jan 2023

Nanobubble-Induced Aggregation Of Ultrafine Particles: A Molecular Dynamics Study, Eric Bird, Zhi Liang

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Nanobubble-induced aggregation (NBIA) of fine and ultrafine particles in liquid is a promising method for enhancing floatation rates in mineral processing, cleaning contaminants from water, and reviving marine ecosystems. Although the current experimental techniques can measure the nanobubble capillary force between two surfaces with controlled approach speed, they are not capable of imaging NBIA dynamics of fine/ultrafine particles by real-time observation with nanoscale spatial resolution. In this work, we use molecular dynamics (MD) simulations to study dynamics of NBIA of Ag particles in a Lennard-Jones fluid system. The molecular-level modeling allows us to study microscopic details of NBIA dynamics that …

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Microstructure, Mechanical Properties And Oxidation Behavior Of Refractory Multi-Principal Element Alloys By Laser Remelting And Conventional Manufacturing, Visharad Jalan, Seth Crawford, Sung Heng Wu, Frank W. Liou, Haiming Wen Jan 2023

Microstructure, Mechanical Properties And Oxidation Behavior Of Refractory Multi-Principal Element Alloys By Laser Remelting And Conventional Manufacturing, Visharad Jalan, Seth Crawford, Sung Heng Wu, Frank W. Liou, Haiming Wen

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Refractory Multi-Principal Element Alloys (RMPEAs), HfNbTaTiZr, (HfNbTaTiZr)9Cr, and (HfNbTaTiZr)9Al, Were Manufactured using Vacuum Arc Melting Followed by Laser Remelting to Mimic Additive Manufacturing. the Microhardness of the As-Cast HfNbTaTiZr, (HfNbTaTiZr)9Cr, and (HfNbTaTiZr)9Al Samples after Arc Melting Was Measured as 6.20, 7.63, and 6.89 Gpa, respectively. after Laser Remelting and Re-Solidification, the Hardness Increased by ~ 30% for Each Composition; the Hardest Was (HfNbTaTiZr)9Cr Measured at 9.60 GPa, While the Softest Was HfNbTaTiZr with a Hardness of 8.42 GPa, Which Was Still Harder Compared to All the Other Samples. the Addition …

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Decoupling Optimization For Complex Pdn Structures Using Deep Reinforcement Learning, Ling Zhang, Li Jiang, Jack Juang, Zhiping Yang, Er Ping Li, Chulsoon Hwang Jan 2023

Decoupling Optimization For Complex Pdn Structures Using Deep Reinforcement Learning, Ling Zhang, Li Jiang, Jack Juang, Zhiping Yang, Er Ping Li, Chulsoon Hwang

Electrical and Computer Engineering Faculty Research & Creative Works

This Article Presents a New Optimization Method for Complex Power Distribution Networks (PDNs) with Irregular Shapes and Multilayer Structures using Deep Reinforcement Learning (DRL), Which Has Not Been Considered Before. a Fast Boundary Integration Method is Applied to Compute the Impedance Matrix of a PDN Structure. Subsequently, a New DRL Algorithm based on Proximal Policy Optimization (PPO) is Proposed to Optimize the Decoupling Capacitor (Decap) Placement by Minimizing the Number of Decaps While Satisfying the Desired Target Impedance. in the Proposed Approach, the PDN Structure Information is Encoded into Matrices and Serves as the Input of the DRL Algorithm, Which …

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A Throughput Fast Measurement Method For Two-Antenna Equipped Wireless Mimo Terminals, Penghui Shen, Quan Yu, Daryl G. Beetner, Yihong Qi Jan 2023

A Throughput Fast Measurement Method For Two-Antenna Equipped Wireless Mimo Terminals, Penghui Shen, Quan Yu, Daryl G. Beetner, Yihong Qi

Electrical and Computer Engineering Faculty Research & Creative Works

According to the Third Generation Partnership Project Specification, a Period of 8-12.8 H is Required to Evaluate the Multiple-Input-Multiple-Output (MIMO) Performance of a Wireless Terminal for a Single Frequency Point and Channel Model Combination. the Following Article Proposes a Semi-Simulation, Semi-Measurement-Based MIMO throughput Modeling Scheme Which Can Reduce the 8-12.8-H Measurement Time to 40-60 Min, Corresponding to More Than a Ten Times Improvement of the Test Efficiency, Without Loss of the Test Accuracy.

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Skin Lesion Segmentation In Dermoscopic Images With Noisy Data, Norsang Lama, Jason Hagerty, Anand Nambisan, Ronald Joe Stanley, William Van Stoecker Jan 2023

Skin Lesion Segmentation In Dermoscopic Images With Noisy Data, Norsang Lama, Jason Hagerty, Anand Nambisan, Ronald Joe Stanley, William Van Stoecker

Electrical and Computer Engineering Faculty Research & Creative Works

We Propose a Deep Learning Approach to Segment the Skin Lesion in Dermoscopic Images. the Proposed Network Architecture Uses a Pretrained Efficient Net Model in the Encoder and Squeeze-And-Excitation Residual Structures in the Decoder. We Applied This Approach on the Publicly Available International Skin Imaging Collaboration (ISIC) 2017 Challenge Skin Lesion Segmentation Dataset. This Benchmark Dataset Has Been Widely Used in Previous Studies. We Observed Many Inaccurate or Noisy Ground Truth Labels. to Reduce Noisy Data, We Manually Sorted All Ground Truth Labels into Three Categories — Good, Mildly Noisy, and Noisy Labels. Furthermore, We Investigated the Effect of Such …

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Methodology For Analyzing Coupling Mechanisms In Rfi Problems Based On Peec, Xu Wang, Anfeng Huang, Wei Zhang, Reza Yazdani, Donghyun Kim, Takashi Enomoto, Taketoshi Sekine, Kenji Araki, Jun Fan, Chulsoon Hwang Jan 2023

Methodology For Analyzing Coupling Mechanisms In Rfi Problems Based On Peec, Xu Wang, Anfeng Huang, Wei Zhang, Reza Yazdani, Donghyun Kim, Takashi Enomoto, Taketoshi Sekine, Kenji Araki, Jun Fan, Chulsoon Hwang

Electrical and Computer Engineering Faculty Research & Creative Works

In This Article, a Method for Analyzing Coupling Mechanisms in Radio Frequency Interference (RFI) Problems is Proposed. the Partial Element Equivalent Circuit (PEEC) Method is First Used to Derive the Retarded Inductances and Capacitances between Different Mesh Cells. with the Introduction of a Novel Partitioning Algorithm, the Capacitive Coupling and Inductive Coupling between Arbitrary Layout Parts Can Be Quantified based on the Magnitude of the Displacement Current and Induced Voltage Drop. the Accuracy of the PEEC Models is Validated by Comparison with Different Commercial Tools. the Proposed Coupling Mechanism Analysis Flow Provides a Useful Prelayout Tool for RFI Risk Analysis.

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Natural Organic Fructose-Based Nonvolatile Resistive Switching Memory For Environmental Sustainability In Computing, Yuan Xing, Feng Zhao Jan 2023

Natural Organic Fructose-Based Nonvolatile Resistive Switching Memory For Environmental Sustainability In Computing, Yuan Xing, Feng Zhao

Electrical and Computer Engineering Faculty Research & Creative Works

The fast growth and wide applications of Internet of Things (IoT) require enormous amounts of energy consumption and hardware devices for computation, which present significant challenges of energy efficiency and environmental sustainability. Von Neumann computing architecture is reaching its bottleneck and limited by low energy efficiency. Fabrication of conventional semiconductor devices results in depletion of nonrenewable resources, while the disposal of these devices causes electronic waste with serious ecological, health, and economic issues. One potential solution to address these challenges simultaneously is by brain-like neuromorphic computing with essential hardware components made from natural organic materials for energy efficient operation, sustainable …

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A Machine Learning Approach To Support Neuromorphic Device Design And Microfabrication, Abdi Yamil Vicenciodelmoral, Md Mehedi Hasan Tanim, Feng Zhao, Xinghui Zhao Jan 2023

A Machine Learning Approach To Support Neuromorphic Device Design And Microfabrication, Abdi Yamil Vicenciodelmoral, Md Mehedi Hasan Tanim, Feng Zhao, Xinghui Zhao

Electrical and Computer Engineering Faculty Research & Creative Works

Neuromorphic chips provide a potential solution for sustainable computing, as they attempt to mimic the neuronal architectures in human brain and show great potentials in reducing energy consumption in the order of magnitude and also improve the computational performance. However, the fabrication process for neuromorphic chips is costly and currently based on trial-and-error, which adds complexity to the design process. In this paper, we address these challenges by designing and developing machine learning guided microfabrication process for Resistive Random Access Memory (RRAM), which is a key device in neuromorphic chips. Specifically, our research makes the following contributions: 1) we successfully …

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An Extendable High Step-Up Dc-Dc Converter For Renewable Energy Applications, Saeed Habibi, Ramin Rahimi, Mehdi Ferdowsi, Pourya Shamsi Jan 2023

An Extendable High Step-Up Dc-Dc Converter For Renewable Energy Applications, Saeed Habibi, Ramin Rahimi, Mehdi Ferdowsi, Pourya Shamsi

Electrical and Computer Engineering Faculty Research & Creative Works

In this paper, a high step-up DC-DC converter based on a switched-inductor-capacitor-diode (SLCD) cell is proposed. the proposed converter provides a high voltage gain, low voltage stress on the power switches and diodes, and a low input current ripple. Moreover, the proposed converter is extendable, meaning that the voltage gain could be further increased by using a higher number of proposed cells in the topology. the steady-state analysis and comparison of the proposed converter to the other existing converters are presented. a 200 W, 40 V to 380 V experimental setup is developed to verify the steady-state analysis of the …

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Comparative Adjudication Of Noisy And Subjective Data Annotation Disagreements For Deep Learning, Scott David Williams Jan 2023

Comparative Adjudication Of Noisy And Subjective Data Annotation Disagreements For Deep Learning, Scott David Williams

Browse all Theses and Dissertations

Obtaining accurate inferences from deep neural networks is difficult when models are trained on instances with conflicting labels. Algorithmic recognition of online hate speech illustrates this. No human annotator is perfectly reliable, so multiple annotators evaluate and label online posts in a corpus. Labeling scheme limitations, differences in annotators' beliefs, and limits to annotators' honesty and carefulness cause some labels to disagree. Consequently, decisive and accurate inferences become less likely. Some practical applications such as social research can tolerate some indecisiveness. However, an online platform using an indecisive classifier for automated content moderation could create more problems than it solves. …

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