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2024

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Articles 661 - 690 of 1004

Full-Text Articles in Materials Science and Engineering

Test On Water Mist Wrapped Dust Reduction Technology For Tunnels, Wang Yijun, Wang Fei, Jia Yuedi, Pan Weihua, He Xingchun, Yao Wenhui Mar 2024

Test On Water Mist Wrapped Dust Reduction Technology For Tunnels, Wang Yijun, Wang Fei, Jia Yuedi, Pan Weihua, He Xingchun, Yao Wenhui

Journal of China & Foreign Highway

In order to eliminate the dust produced by tunnel blasting more quickly and effectively，two kinds of mist spray and dust reduction schemes were put forward，which were the “air duct water mist wrapped type ” and the “vehicle-mounted water mist wrapped type ”.The field test was carried out on Jiaoding Tunnel in Yunnan.The results show that for the dust reduction technology scheme of “air duct water mist wrapped type ”，the dust concentration of the No.1 characteristic position at the tunnel face decreases to 3.87 mg/m3 after 10 minutes of dust reduction，which meets the specification requirements.For the dust reduction technology of “vehicle-mounted …

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Numerical Simulation On Bearing Characteristics Of Tunnel‑Type Anchorage Of A Grand Bridge Over Qingjiang River, Yin Hongmei, Shi Qian, Zhang Yihu Mar 2024

Numerical Simulation On Bearing Characteristics Of Tunnel‑Type Anchorage Of A Grand Bridge Over Qingjiang River, Yin Hongmei, Shi Qian, Zhang Yihu

Journal of China & Foreign Highway

This paper took the tunnel-type anchorage on the left bank of a grand bridge over the Qingjiang River as an example and established a three-dimensional geological generalization model based on the engineering geological analysis.In addition，the paper used different software to realize the approximate grid discrete division of complex rock mass and tunnel-type anchorage structure.FLAC3D software was used to simulate different working conditions，and the deformation characteristics and bearing capacity of the tunnel-type anchorage were obtained.It is found that the potential failure mode of the tunnel-type anchorage is that the anchor and the rock mass cut by the structural plane on the …

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Expressway Traffic Flow Prediction Based On Data From Multiple Related Toll Stations, Zhang Yang, Yao Fangyu, Yang Shumin Mar 2024

Expressway Traffic Flow Prediction Based On Data From Multiple Related Toll Stations, Zhang Yang, Yao Fangyu, Yang Shumin

Journal of China & Foreign Highway

The strong inter-economic connection makes a spatial correlation between traffic data from multiple related toll stations between urban cluster regions，and an accurate description of this connection can improve the accuracy of expressway traffic flow prediction.However，due to many uncertainties，the correlation is difficult to be captured and quantified.To solve this problem，an ATGCN-ResGRU deep learning-based expressway traffic flow prediction method was proposed.By combining attention mechanisms，three graph convolutional networks （GCN ） topological networks with high，medium，and low attention levels were constructed，and spatial learning data was obtained according to the weighted attention level of each network.The connection of multiple related toll stations was quantified and graded.At …

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Study On Length Of Deceleration Lane Of Left Off‑Ramp For Urban Underground Interchanges Based On Traffic Conflicts, Wang Hailiang, Cheng Chong, Guan Hong, Ding Naikan Mar 2024

Study On Length Of Deceleration Lane Of Left Off‑Ramp For Urban Underground Interchanges Based On Traffic Conflicts, Wang Hailiang, Cheng Chong, Guan Hong, Ding Naikan

Journal of China & Foreign Highway

To set a reasonable range of the length of the deceleration lane in the diverge area of the left off-ramp for urban underground interchanges，the effects of the length of the deceleration lane，as well as interactions between traffic volumes and design speeds of mainline and ramp on traffic conflict in the diverge area，were exami ned.By taking the underground interchange of the Wuhan East-South Lakes Tunnel Project as an example，the VISSIM micro traffic simulation test was carried out，and the conflict rate （RCR） and exposed time to collision （TTET） were extracted.The results show that ① when the length of the deceleration lane increases，the …

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Study On Safety Risk Assessment System For Waste Dump Of Mountainous Expressways, Ye Xian, Yin Hao, Zhao Xin, Wang Guanqun, Gao Yu Mar 2024

Study On Safety Risk Assessment System For Waste Dump Of Mountainous Expressways, Ye Xian, Yin Hao, Zhao Xin, Wang Guanqun, Gao Yu

Journal of China & Foreign Highway

The safety of waste dump projects of mountainous expressways is related to environmental protection，water and soil conservation，highway building protection，and downstream environment-sensitive point protection，so it is necessary to put forward safety assessment methods.Based on the data analysis of 1 369 waste dumps in Yunnan Province，the safety risk factors of the waste dump engineering were proposed and summarized as five primary indicators，including site selection and design factors，construction factors，regional geological factors，external influencing factors，and data integrity factors，and 18 secondary indicators were further put forward.The group decision-making analytic hierarchy process （AHP ） model was established，and the weight of secondary indexes was determined by 64 technical …

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Carbon Emission Calculation And Scheme Selection For Roadbed Drainage Ditches By Mechanized Construction, Xing Hao, Wu Jiarun, Li Han, Lin Yuliang, Guo Dongdong Mar 2024

Carbon Emission Calculation And Scheme Selection For Roadbed Drainage Ditches By Mechanized Construction, Xing Hao, Wu Jiarun, Li Han, Lin Yuliang, Guo Dongdong

Journal of China & Foreign Highway

Aligned with the peak carbon and neutrality goals，the mechanized construction of roadbed drainage ditches should consider not only construction efficiency and economic factors but also carbon emissions.This study，centered on the Meng-LYU highway，devised approaches to calculate roadbed drainage ditches' carbon emissions and investment costs across three stages：building material production，transportation，and construction.By introducing the concept of carbon trading to align carbon emissions and investment costs，a comprehensive comparison was conducted between the conventional supporting formwork method and the hydraulically powered sliding formwork method regarding equivalent carbon emissions.An orthogonal experiment was conducted involving the upper length of the roadbed drainage ditch，pouring thickness，haul distance，and construction length …

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Technical Essentials Of Road Geometric Design In Serbia, Xu Da, Yang Xueyong, Yuan Yingshuang, Chen Dongsheng Mar 2024

Technical Essentials Of Road Geometric Design In Serbia, Xu Da, Yang Xueyong, Yuan Yingshuang, Chen Dongsheng

Journal of China & Foreign Highway

With the continuous advancement of China's Belt and Road Initiative，more and more Chinese enterprises are participating in the construction of engineering projects in Central and Eastern Europe，which brings some challenges for designers to master and use local codes for engineering design and consultation.According to the concrete practice of road reconstruction design of Hungary-Serbia Railway （Serbia section ），the application of horizontal and vertical indexes in road geometric design in Serbian was summarized.It is found that road design in Serbian has perfect design standards and systems.The Serbian code and the Chinese code are relatively close in terms of road geometric design standards，and …

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Analysis On Design Concept Of Subgrade And Pavement Of Colombia High‑Grade Highway, Liu Tao, Hu Guanhua, Yuan Yi Mar 2024

Analysis On Design Concept Of Subgrade And Pavement Of Colombia High‑Grade Highway, Liu Tao, Hu Guanhua, Yuan Yi

Journal of China & Foreign Highway

Colombian highway design predominantly adheres to American Standards，emphasizing design concepts reflective of the United States while encompassing Colombia's engineering design habits，concepts，and characteristics.This paper introduced the main design schemes of the Colombia MAR 2 Highway Project in northern Colombia，including protection engineering，drainage engineering，subgrade filling，spoil ground，and pavement.It conducted a comparative analysis between Colombian and Chinese design concepts，highlighting similarities and disparities，and put forward the thinking of mutual learning.

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On The Use Of Machine Learning And Data-Transformation Methods To Predict Hydration Kinetics And Strength Of Alkali-Activated Mine Tailings-Based Binders, Sahil Surehali, Taihao Han, Jie Huang, Aditya Kumar, Narayanan Neithalath Mar 2024

On The Use Of Machine Learning And Data-Transformation Methods To Predict Hydration Kinetics And Strength Of Alkali-Activated Mine Tailings-Based Binders, Sahil Surehali, Taihao Han, Jie Huang, Aditya Kumar, Narayanan Neithalath

Electrical and Computer Engineering Faculty Research & Creative Works

The escalating production of mine tailings (MT), a byproduct of the mining industry, constitutes significant environmental and health hazards, thereby requiring a cost-effective and sustainable solution for its disposal or reuse. This study proposes the use of MT as the primary ingredient (≥70%mass) in binders for construction applications, thereby ensuring their efficient upcycling as well as drastic reduction of environmental impacts associated with the use of ordinary Portland cement (OPC). The early-age hydration kinetics and compressive strength of MT-based binders are evaluated with an emphasis on elucidating the influence of alkali activation parameters and the amount of slag or cement …

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Synthesis And Energetic Characterization Of Borane-Amines On High-Nitrogen Heterocycles, Randy Lin, Nicholas F. Scherschel, Matthias Zeller, Stephen G. Hamlin, Madison Snyder, Steven Son, P. Veeraraghavan Ramachandran, Davin G. Piercey Mar 2024

Synthesis And Energetic Characterization Of Borane-Amines On High-Nitrogen Heterocycles, Randy Lin, Nicholas F. Scherschel, Matthias Zeller, Stephen G. Hamlin, Madison Snyder, Steven Son, P. Veeraraghavan Ramachandran, Davin G. Piercey

Purdue University Libraries Open Access Publishing Fund

Borane-amines have garnered attention over the last several decades in a variety of applications, ranging from hydrogen storage materials to hypergolic fuel systems. An investigation into the synthesis of borane-amines with high-nitrogen content heterocycles was undertaken in this work. Borane-amines were formed by the reaction of BH3·Me2S in tetrahydrofuran (THF) with the requisite nitrogen-containing heterocycle and isolated by placing the crude reaction mixture in hexanes to precipitate the product. X-ray crystallography, thermogravimetric analysis (TGA), high resolution mass spectroscopy (HRMS), 1H NMR, 13C NMR, and 11B NMR were utilized for product characterization, while impact and friction sensitivity testing were conducted to …

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Effect Of The Filler Morphology On The Crystallization Behavior And Dielectric Properties Of The Polyvinylidene Fluoride-Based Composite, Suzana Filipović, Nina Obradović, Cole Corlett, William G. Fahrenholtz, Martin Rosenschon, Ekkehard Füglein, Radovan Dojčilović, Dragana Tošić, Jovana Petrović, Antonije Đorđević, Branislav Vlahović, Vladimir B. Pavlović Mar 2024

Effect Of The Filler Morphology On The Crystallization Behavior And Dielectric Properties Of The Polyvinylidene Fluoride-Based Composite, Suzana Filipović, Nina Obradović, Cole Corlett, William G. Fahrenholtz, Martin Rosenschon, Ekkehard Füglein, Radovan Dojčilović, Dragana Tošić, Jovana Petrović, Antonije Đorđević, Branislav Vlahović, Vladimir B. Pavlović

Materials Science and Engineering Faculty Research & Creative Works

Ceramic/polymer composites can be chemically stable, mechanically strong, and flexible, which make them candidates for electric devices, such as pressure or temperature sensors, energy storage or harvesting devices, actuators, and so forth. Depending on the application, various electrical properties are of importance. Polymers usually have low dielectric permittivity, but increased dielectric permittivity can be achieved by the addition of the ceramic fillers with high dielectric constant. With the aim to enhance dielectric properties of the composite without loss of flexibility, 5 wt.% of BaTiO3-Fe2O3 powder was added into a polyvinylidene fluoride matrix. The powder was …

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A Phenomenological Thermodynamic Energy Density Function For Ferroelectric Wurtzite Al1−Xscxn Single Crystals, Yijia Gu, Andrew C. Meng, Aiden Ross, Long Qing Chen Mar 2024

A Phenomenological Thermodynamic Energy Density Function For Ferroelectric Wurtzite Al1−Xscxn Single Crystals, Yijia Gu, Andrew C. Meng, Aiden Ross, Long Qing Chen

Materials Science and Engineering Faculty Research & Creative Works

A Landau-Devonshire thermodynamic energy density function for ferroelectric wurtzite aluminum scandium nitride (Al1−xScxN) solid solution is developed. It is parametrized using available experimental and theoretical data, enabling the accurate reproduction of composition-dependent ferroelectric properties, such as spontaneous polarization, dielectric permittivity, and piezoelectric constants, for both bulk and thin films. The maximum concentration of Sc for the wurtzite structure to remain ferroelectric is found to be 61 at. %. A detailed analysis of Al1−xScxN thin films reveals that the ferroelectric phase transition and properties are insensitive to substrate strain. This study lays the foundation for quantitative modeling of novel ferroelectric wurtzite …

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Raman Spectroscopy Of Gan On Si With Varied Thin Film Thickness For High-Temperature Semiconductor Devices, Manika Tun Nafisa Mar 2024

Raman Spectroscopy Of Gan On Si With Varied Thin Film Thickness For High-Temperature Semiconductor Devices, Manika Tun Nafisa

Symposium of Student Scholars

This study explores the potential of GaN on Si thin films as a promising material for high-temperature semiconductor devices, owing to its impressive thermal properties and performance characteristics. Two GaN on Si samples were grown using Metal Organic Chemical Vapor Deposition (MOCVD), with different film thicknesses, and their potential for high-temperature applications was comprehensively assessed by performing Raman spectroscopy at various temperature levels. The experimental results provided valuable insights into the material's behavior at elevated temperatures. At 300°C, the GaN E2 (High) peak showed a Raman shift at 562.38 cm⁻¹ for high-thickness samples and 561.49 cm⁻¹ for low-thickness samples. …

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Mbe Growth Of Sb Based Alloys Using Interfacial Misfit Arrays For Mwir Devices, Fatih Furkan Ince Mar 2024

Mbe Growth Of Sb Based Alloys Using Interfacial Misfit Arrays For Mwir Devices, Fatih Furkan Ince

Optical Science and Engineering ETDs

This thesis explores the monolithic integration of antimonide based narrow bandgap semiconductors on commercially available substrates for mid-wave infrared (MWIR) devices. The research focuses on the integration and growth of antimonide based alloys using the interfacial misfit dislocation (IMF) arrays to enhance the cost efficiency, manufacturability and performance. The study particularly investigates the relaxation mechanisms of antimonide alloys on InAs and InP substrates, assessing the impact of mismatch strain on the quality of epilayers. The IMF arrays are examined using high-resolution transmission electron microscopy (HR-TEM) and x-ray diffraction (XRD), revealing information about the effective strain relief mechanisms behind IMF arrays …

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Corrigendum To "Comparing Structure-Property Evolution For Pm-Hip And Forged Alloy 625 Irradiated With Neutrons To 1dpa" [Mater. Sci. Eng. A (2022) 144058], Caleb Clement, Sowmya Panuganti, Patrick H. Warren, Yangyang Zhao, Yu Lu, Katelyn Wheeler, David Frazer, Donna P. Guillen, David W. Gandy, Janelle P. Wharry Mar 2024

Corrigendum To "Comparing Structure-Property Evolution For Pm-Hip And Forged Alloy 625 Irradiated With Neutrons To 1dpa" [Mater. Sci. Eng. A (2022) 144058], Caleb Clement, Sowmya Panuganti, Patrick H. Warren, Yangyang Zhao, Yu Lu, Katelyn Wheeler, David Frazer, Donna P. Guillen, David W. Gandy, Janelle P. Wharry

Materials Science and Engineering Faculty Publications and Presentations

The authors regret that after publication, they discovered that the dislocation loop number density was undercounted by a factor of 100 for both the PM-HIP and forged specimens. While this does not change the original major conclusions, this necessitates a change in the results presentation (Sections 3.2 and 4.1) and calculated hardening (Table 3, Fig. 5). Corrections to these affected sections are provided in this corrigendum.

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The Interplay Of Spin, Charge, And Heat: From Metal/Insulator Heterostructures To Perovskite Bilayers, Sam M. Bleser Mar 2024

The Interplay Of Spin, Charge, And Heat: From Metal/Insulator Heterostructures To Perovskite Bilayers, Sam M. Bleser

Electronic Theses and Dissertations

In this dissertation begin with an investigation of non-local spin transport in an amorphous germanium (a-Ge) sample via the inverse spin Hall effect (ISHE). In that study we show that commonly used techniques such as differential conductance and delta mode of a paired Keithley 6221/2182a for non-local resistance measurements can lead to false indicators of spin transport. Next, we turn out attention to a thickness dependent study in thermally-evaporated chromium (Cr) thin films on a bulk polycrystalline yttrium-iron-garnet (YIG) substrate. This project analyzed the spin transport in the Cr films versus thickness via the longitudinal spin Seebeck effect (LSSE). This …

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Thermal, Electrical, And Spin Transport: Encompassing Low-Damping Ferromagnets And Antiferromagnetic/Ferromagnetic Heterostructures, Matthew Ryan Natale Mar 2024

Thermal, Electrical, And Spin Transport: Encompassing Low-Damping Ferromagnets And Antiferromagnetic/Ferromagnetic Heterostructures, Matthew Ryan Natale

Electronic Theses and Dissertations

Continuing technological advancements bring forth escalating challenges in global energy consumption and subsequent power dissipation, posing significant economic and environmental concerns. In response to these difficulties, the fields of thermoelectrics, spintronics, and spincaloritronics emerge as contemporary solutions, each presenting unique advantages. Thermoelectric devices, based on the Seebeck effect, other a passive, carbon-free energy generating solution from waste heat. Although current thermoelectric technology encounters hurdles in achieving optimal efficiencies without intricate designs or complex materials engineering, recently research into low-damping metallic ferromagnetic thin films have provided a new method to enhance spin wave lifetimes, thus contributing to thermoelectric voltage improvements. As …

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Finite Element Analysis Of Thermal-Mechanical Instabilities In Nonmetallic Friction Composite Material, Joseph-Shaahu Shaahu Mar 2024

Finite Element Analysis Of Thermal-Mechanical Instabilities In Nonmetallic Friction Composite Material, Joseph-Shaahu Shaahu

Electronic Theses and Dissertations

Thermal-mechanical instability (TMI) has been a research topic of interest as it focuses a lot on transportation systems. Thermal-mechanical instability was first noticed in railway and experimentally studied with a pin-to-pin or pin-to-surface setup of sliding contact. The topic has been extended into brakes and clutches which are two of the most common sliding systems most susceptible to thermal buckling and thermoelastic instability (TEI), where thermal buckling and thermoelastic instability are two sub-categories of thermal-mechanical instability. Thermal-mechanical instability is an ongoing research to better understand the phenomenon and the limits at which such instability occurs. This work delved into the …

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Dielectric Properties Of Polycrystalline And Single-Crystal Magnesium Oxide At High Temperatures, Alan Devoe, Hung Trinh, Fatih Dogan Mar 2024

Dielectric Properties Of Polycrystalline And Single-Crystal Magnesium Oxide At High Temperatures, Alan Devoe, Hung Trinh, Fatih Dogan

Materials Science and Engineering Faculty Research & Creative Works

The electrical properties of high-purity magnesium oxide (MgO) samples sintered between 1500 and 1650°C were investigated up to 800°C. Dielectric constant, loss tangent and electrical conductivity were measured between 25 and 800°C. Optimum electrical properties were obtained for the sample sintered at 1600°C. The impurities in polycrystalline and single crystal MgO were discussed to understand their effect on electrical properties and the role of grain boundaries. Higher dielectric losses of polycrystalline samples as compared to the single crystal MgO were attributed to the presence of grain boundaries. MgO could be a useful dielectric material for capacitor applications up to 600°C.

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The Janssen Effect And The Chini Ordinary Differential Equation, Adam Rogers, George Dyck, Jitendra Paliwal, Kurt Hildebrand, Michael D. Montross, Aaron P. Turner Mar 2024

The Janssen Effect And The Chini Ordinary Differential Equation, Adam Rogers, George Dyck, Jitendra Paliwal, Kurt Hildebrand, Michael D. Montross, Aaron P. Turner

Chemical and Materials Engineering Faculty Publications

The Janssen effect describes the increase in pressure with depth in granular materials. However, the original Janssen formulation treats the density as constant. In this work, we examine parametric density models that depend on both pressure and moisture content and allow for temperature dependence to be easily included. We focus on physically-motivated empirical models that are built on power-law terms. These power-law terms correspond to thermodynamic equations of state, such as the ideal gas law, and polytropic processes. When coupled with the Janssen ordinary differential equation (ODE), these power-law models have the form of a Chini ODE. We study the …

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Protocol For Modeling And Simulating Lithiation-Induced Stress In Largely Deformed Spherical Nanoparticles Using Comsol, Yong Li, Yungpeng Guo, Yunhao Wu, Yin Rao, Kai Zhang, Dashun Liu, Fuqian Yang Mar 2024

Protocol For Modeling And Simulating Lithiation-Induced Stress In Largely Deformed Spherical Nanoparticles Using Comsol, Yong Li, Yungpeng Guo, Yunhao Wu, Yin Rao, Kai Zhang, Dashun Liu, Fuqian Yang

Chemical and Materials Engineering Faculty Publications

Here, we present a finite element method-based scheme for solving coupled par- tial differential equations (PDEs) for the analysis of lithiation-induced stress in largely deformed spherical nanoparticles via the PDE module in COMSOL. We describe steps for software installation and setting PDEs, initial/boundary condi- tions, and mesh parameters. We then detail procedures for dividing the mesh and analyzing lithium trapping during electrochemical cycling. This protocol can also be extended to analyze a wide range of problems involving diffusion-induced stress. For complete details on the use and execution of this protocol, please refer to Li et al.

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Toward Smart And Sustainable Cement Manufacturing Process: Analysis And Optimization Of Cement Clinker Quality Using Thermodynamic And Data-Informed Approaches, Jardel P. Gonçalves, Taihao Han, Gaurav Sant, Narayanan Neithalath, Jie Huang, Aditya Kumar Mar 2024

Toward Smart And Sustainable Cement Manufacturing Process: Analysis And Optimization Of Cement Clinker Quality Using Thermodynamic And Data-Informed Approaches, Jardel P. Gonçalves, Taihao Han, Gaurav Sant, Narayanan Neithalath, Jie Huang, Aditya Kumar

Electrical and Computer Engineering Faculty Research & Creative Works

Cement manufacturing is widely recognized for its harmful impacts on the natural environment. In recent years, efforts have been made to improve the sustainability of cement manufacturing through the use of renewable energy, the capture of CO2 emissions, and partial replacement of cement with supplementary cementitious materials. To further enhance sustainability, optimizing the cement manufacturing process is essential. This can be achieved through the prediction and optimization of clinker phases in relation to chemical compositions of raw materials and manufacturing conditions. Cement clinkers are produced by heating raw materials in kilns, where both raw material compositions and processing conditions …

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Spontaneous Alignment Of Myotubes Through Myogenic Progenitor Cell Migration, Lauren E. Mehanna, Adrianna R. Osborne, Charlotte A. Peterson, Brad J. Berron Mar 2024

Spontaneous Alignment Of Myotubes Through Myogenic Progenitor Cell Migration, Lauren E. Mehanna, Adrianna R. Osborne, Charlotte A. Peterson, Brad J. Berron

Chemical and Materials Engineering Faculty Publications

In large-volume muscle injuries, widespread damage to muscle fibers and the surrounding connective tissue prevents myogenic progenitor cells (MPCs) from initiating repair. There is a clinical need to rapidly fabricate large muscle tissue constructs for integration at the site of large volume muscle injuries. Most strategies for myotube alignment require microfabricated structures or prolonged orientation times. We utilize the MPC’s natural propensity to close gaps across an injury site to guide alignment on collagen I. When MPCs are exposed to an open boundary free of cells, they migrate unidirectionally into the cell-free region and align perpendicular to the original boundary …

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Local Strain Quantification Of A Porous Carbon Fiber Network Material, Robert N Quammen, Paul F. Rottmann Mar 2024

Local Strain Quantification Of A Porous Carbon Fiber Network Material, Robert N Quammen, Paul F. Rottmann

Chemical and Materials Engineering Faculty Publications

While porous materials’ wide range of attractive functional properties have led to their development for a variety of applications, their intrinsically stochastic microstructures prevent straightforward approaches to predicting their mechanical behavior. This is attributed to the mechanisms that govern the macroscale behavior of these materials operating on multiple microstructure-specific length scales spanning several orders of magnitude. The goal of this work was to experimentally observe these operative deformation mechanisms to better improve the development of mechanism-informed models that more accurately predict the behavior of these materials. In this study compression tests were conducted on a porous carbon fiber network material. …

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A Priori Procedure To Establish Spinodal Decomposition In Alloys, Simon Divilov, Hagen Eckert, Cormac Toher, Rico Friedrich, Adam C. Zettel, Donald W. Brenner, William G. Fahrenholtz, Douglas E. Wolfe, Eva Zurek, Jon Paul Maria, Nico Hotz, Xiomara Campilongo, Stefano Curtarolo Mar 2024

A Priori Procedure To Establish Spinodal Decomposition In Alloys, Simon Divilov, Hagen Eckert, Cormac Toher, Rico Friedrich, Adam C. Zettel, Donald W. Brenner, William G. Fahrenholtz, Douglas E. Wolfe, Eva Zurek, Jon Paul Maria, Nico Hotz, Xiomara Campilongo, Stefano Curtarolo

Materials Science and Engineering Faculty Research & Creative Works

Spinodal decomposition can improve a number of essential properties in materials, especially hardness. Yet, the theoretical prediction of the onset of this phenomenon (e.g., temperature) and its microstructure (e.g., wavelength) often requires input parameters coming from costly and time-consuming experimental efforts, hindering rational materials optimization. Here, we present a procedure where such parameters are not derived from experiments. First, we calculate the spinodal temperature by modeling nucleation in the solid solution while approaching the spinode boundary. Then, we compute the spinodal wavelength self-consistently using a few reasonable approximations. Our results show remarkable agreement with experiments and, for NiRh, the calculated …

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Spatiotemporal Dispersion Compensation For A 200-Thz Noncollinear Optical Parametric Amplifier, William P. Carbery, Laurie A. Bizimana, Matthew S. Barclay, Nicholas D. Wright, Paul H. Davis, William B. Knowlton, Ryan D. Pensack, Paul C. Arpin, Daniel B. Turner Mar 2024

Spatiotemporal Dispersion Compensation For A 200-Thz Noncollinear Optical Parametric Amplifier, William P. Carbery, Laurie A. Bizimana, Matthew S. Barclay, Nicholas D. Wright, Paul H. Davis, William B. Knowlton, Ryan D. Pensack, Paul C. Arpin, Daniel B. Turner

Materials Science and Engineering Faculty Publications and Presentations

A noncollinear optical parametric amplifier (NOPA) can produce few-cycle femtosecond laser pulses that are ideally suited for time-resolved optical spectroscopy measurements. However, the nonlinear-optical process giving rise to ultrabroadband pulses is susceptible to spatiotemporal dispersion problems. Here, we detail refinements, including chirped-pulse amplification (CPA) and pulse-front matching (PFM), that minimize spatiotemporal dispersion and thereby improve the properties of ultrabroadband pulses produced by a NOPA. The description includes a rationale behind the choices of optical and optomechanical components, as well as assessment protocols. We demonstrate these techniques using a 1 kHz, second-harmonic Ti:sapphire pump configuration, which produces ∼5-fs duration pulses that …

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Characterization Of An Omega Type Bi-Anisotropic Material, Moriel Gindi Mar 2024

Characterization Of An Omega Type Bi-Anisotropic Material, Moriel Gindi

Theses and Dissertations

A theory is presented for the extraction of the complete set of material parameters for a bi-anisotropic sample consisting of conductive omega-type particles governed by the mm21′ point-group symmetry. A rectangular-to-square wave-guide can be used to obtain the required measurements by allowing three distinct orientations of the material. The focus of this work is to develop the appropriate theory detailing the derivation of how the material parameters are extracted from the measurements in an analytical methodology that is similar in manner to the well-known Nicolson-Ross-Weir (NRW) algorithm.

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Spectroscopic Characterization Of Trivalent Holmium In Liyf4 And Bay2F8 Crystals, Vivian R. Hedberg Mar 2024

Spectroscopic Characterization Of Trivalent Holmium In Liyf4 And Bay2F8 Crystals, Vivian R. Hedberg

Theses and Dissertations

Yttrium-fluoride crystals doped with trivalent holmium are promising laser gain media for mid-infrared laser systems. To accurately model laser systems, a complete optical characterization of the laser gain medium is required. The key modeling parameters were obtained by a spectroscopic investigation of Ho3+ in LiYF4 and BaY2F8 crystal hosts. Several important mid-infrared laser transitions were characterized at nominal Ho3+ ion concentrations of 10-30 at.%. Polarized emission cross-sections were determined from the fluorescence spectra using the Füchtbauer-Ladenburg method. Polarized absorption cross-sections were obtained using the Integral Reciprocity method. The upper-state lifetimes were measured at room …

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The Thermophysical Properties Of Tco2, Hong Zhong, Jason Lonergan, John S. Mccloy, Scott P. Beckman Mar 2024

The Thermophysical Properties Of Tco2, Hong Zhong, Jason Lonergan, John S. Mccloy, Scott P. Beckman

Materials Science and Engineering Faculty Research & Creative Works

Technetium-99 Is A Highly Radioactive Isotope With A Long Half-Life That Is Common In Nuclear Waste. It Volatizes At A Low Temperature, Which Poses A Significant Challenge To The Clean-Up And Containment Processes. Due To Difficulties In Purifying Technetium Compounds, Their Thermophysical Properties Have Not Been Measured Or Calculated. Here, First Principle Methods Are Used Along With The Quasi Quasi-Harmonic Harmonic Approximation To Compute The Debye Temperature, Volumetric Thermal Expansion Coefficient, Bulk Modulus, And Heat Capacity Of Rutile TcO2 For Temperatures Ranging From 0 To 1500 K And Applied Pressures Ranging From 0 To 255 GPa. The Computed Atomic Structures …

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Influence Of Environmental Barrier Coatings On The Overall Effectiveness Of A Film Cooled Ceramic Matrix Composite Plate, Shane P. Lindsay Mar 2024

Influence Of Environmental Barrier Coatings On The Overall Effectiveness Of A Film Cooled Ceramic Matrix Composite Plate, Shane P. Lindsay

Theses and Dissertations

Silicon carbide ceramic matrix composites, a promising new potential upgrade over the conventional metals currently used for jet engine turbine blades, have a propensity to oxidize in a combustion environment. Engine manufacturers often apply environmental barrier coatings to prevent the composites from oxidizing. What is unclear, however, is how environmental barrier coatings effect underlying composite temperatures. This research examined the coatings’ effects by first characterizing the influence of environmental barrier coatings on the underlying temperature of a protected ceramic, then evaluating the significance of lateral conduction for cooling a coated ceramic, and finally comparing cooling results for coated and uncoated …

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