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Scale-Dependent Plasticity And Nanoindentation Creep Of Geologic Materials, Christopher Thom 2019 University of Pennsylvania

Scale-Dependent Plasticity And Nanoindentation Creep Of Geologic Materials, Christopher Thom

Publicly Accessible Penn Dissertations

Nanoindentation is a commonly used technique in materials science that allows for the determination of the mechanical properties (e.g. hardness, elastic modulus, and creep) of single crystals and polycrystalline aggregates, but it has been severely underutilized for the study of geologic materials. In this dissertation, we demonstrate the effectiveness of nanoindentation for measuring the rheological behavior of a wide range of geologic materials. For all materials tested, including single crystals, polycrystalline samples, and two different natural fault surfaces, we identify an ‘indentation size effect,’ whereby the strength of the material increases with decreasing size of the indent. We explore ...


Structure Prediction Of Self-Assembled Nanoparticle Superlattices, Nathan Robert Horst 2019 Iowa State University

Structure Prediction Of Self-Assembled Nanoparticle Superlattices, Nathan Robert Horst

Graduate Theses and Dissertations

In this dissertation, the self-assembly of nanoparticle superlattices is studied through the development of theoretical models and computational techniques that elucidate the interactions of constituents during the self-assembly process. Specifically, configurational characteristics of various core-shell nanoparticle morphologies are explored with models of increasing complexity, aided by the implementation of molecular dynamics simulations and dynamic lattice theory.


Determination Of The Structure-Processing-Properties Relationship Of Fe-6.5wt%Si, Chad Richard Macziewski 2019 Iowa State University

Determination Of The Structure-Processing-Properties Relationship Of Fe-6.5wt%Si, Chad Richard Macziewski

Graduate Theses and Dissertations

The role of Fe-6.5wt%Si as a soft magnetic material in motor and power generation will continue to increase as power and efficiency demands keep increasing due to high silicon steel’s superior magnetic and electrical properties when operated at high frequencies. However, the presence of brittle phases creates challenges for mass production of the materials and for machining the materials into parts with demanding geometries. Understanding the processing parameters controlling the presence of the brittle phases is necessary to promote high silicon steels as the superior soft magnetic material. This research pioneers the use of in-situ cooling rate ...


Comparative Study Of Analytical Models Of The Gruneisen Parameter Of Metals As Function Of Pressure, Celia Garcia Amparan 2019 University of Texas at El Paso

Comparative Study Of Analytical Models Of The Gruneisen Parameter Of Metals As Function Of Pressure, Celia Garcia Amparan

Open Access Theses & Dissertations

Commonly used Gruneisen parameter (γ) models only hold accurate in limited regimes making them inapplicable for use over wide temperature-pressure conditions. The accuracy of these analytical models of γ and of the thermal expansion of solids are of particular interest as these are considered proxies for quantifying anharmonicity, which may be a significant contribution to the thermal pressure at high temperatures. This work reviews various definitions of γ and their relations to the equations of state and apply them to two simple metals: Tantalum (Ta) and Copper (Cu), for which a high body of experimental data exists. Classical Molecular Dynamics ...


Investigating Using Titanium Zirconium Molybdenum For Additively Manufacturing Aerospace Components, Justin Hunter Vanhoose 2019 University of Texas at El Paso

Investigating Using Titanium Zirconium Molybdenum For Additively Manufacturing Aerospace Components, Justin Hunter Vanhoose

Open Access Theses & Dissertations

Mankind throughout history has possessed an innate characteristic to explore, migrating to new frontiers.The requirement for this travel is most broadly associated with the need to pursue more resources. Rockets have been used as a means of weapons since the Sung Dynasty in the thirteenth empire and have now been integrated for travel/transport. The sophistication of rocketry and propulsion has reached a level to where it is plausible that mankind will be a multi-planetary species. The space industry has grown significantly with the advancement of the sophistication of these rocket technologies. However, a specific challenge to overcome in ...


Exploration And Optimization Of Biomaterials And Cells Required For The Fabrication Of A "Cardiac Patch", Shweta Anil Kumar 2019 University of Texas at El Paso

Exploration And Optimization Of Biomaterials And Cells Required For The Fabrication Of A "Cardiac Patch", Shweta Anil Kumar

Open Access Theses & Dissertations

Cardiac failure induced by myocardial infarction is believed to be one of the primary causes of morbidity and mortality all over the world. Affecting more than 26 million people worldwide, its prevalence has been observed to increase steadily. Myocardial infarction, which intitially begins as the occlusion of of a coronary artery, results in the death of millions of cardiomyocytes by obstructing blood flow to the serviced regions of the myocardium. The dead myocardium is replaced by a dense,collagenous scar which reduces the contractility of the heart, gradually leading to heart attacks. Most of the existing treatment therapies are palliative ...


A Method For Iron Determination During Copper Electrometallurgy And Its Application To The Calculation Of Current Efficiency, Daniel Pedro Cruz 2019 University of Texas at El Paso

A Method For Iron Determination During Copper Electrometallurgy And Its Application To The Calculation Of Current Efficiency, Daniel Pedro Cruz

Open Access Theses & Dissertations

With the objective of developing statistical models that describe iron kinetics under typical copper electrolytes as well as its effects on current efficiency and influence in cathodic and anodic behavior, a detailed electrochemical analysis is done in this work as a contribution to implement hydrometallurgical processes in the refining or winning process to produce high purity copper.

This Thesis evaluates the oxidation-reduction potential (ORP) of the Fe3+/Fe2+ couple in the H2SO4-Fe2(SO4)3-FeSO4-H2O and H2SO4-CuSO4-Fe2(SO4)3-FeSO4-H2O systems, with addition of different copper concentrations and temperatures up to 70°, typically employed in the industry. This study further validates and ...


Tailoring Physical Properties Of Shape Memory Polymers For Fdm-Type Additive Manufacturing, Paulina Aileen Quinonez 2019 University of Texas at El Paso

Tailoring Physical Properties Of Shape Memory Polymers For Fdm-Type Additive Manufacturing, Paulina Aileen Quinonez

Open Access Theses & Dissertations

Shape memory polymers (SMPs) have found applicability in biomedical settings as well as other uses that can take advantage of objects that can change shape upon exposure to stimulus. Integrating polymers with shape memory characteristics into additive manufacturing technologies such as fused deposition modeling (FDMâ?¢) can increase the number of applications this manufacturing platform can be utilized. Currently, polyurethane and polylactic acid (PLA) are two FDMâ?¢-compatible materials that possess shape memory properties. On their own these materials do not have tunable shape memory properties, namely shape recovery and shape fixation. The work presented here entails the development and characterization ...


Tailoring The Mechanical And Optical Properties Of Silicon-Niobium-Nitride Composite Coatings, Cristian Orozco 2019 University of Texas at El Paso

Tailoring The Mechanical And Optical Properties Of Silicon-Niobium-Nitride Composite Coatings, Cristian Orozco

Open Access Theses & Dissertations

Nitride nanocomposite thin films have generated significant attention as a result of their robust mechanical properties, excellent triobology, and good chemical (corrosion) stability. Due to their excellent hardness and high wear resistance NbN coatings have found use in a wide variety of applications such as the coating of cutting tools and to strengthen the surface mechanical properties of superconducting cavities. The mechanical properties of NbN can be further improved through mixing with Si3N4, leading to the formation of a nanocomposite structure. NbN-Si3N4 nanocomposite coatings have been actively studied due to their high hardness, high elastic modulus, and high resistance to ...


Development And Characterization Of Polyethylene Terephthalate (Pet)-Cotton Natural Fiber-Reinforced Composites From Waste Materials, Israel Alejandro Carrete 2019 University of Texas at El Paso

Development And Characterization Of Polyethylene Terephthalate (Pet)-Cotton Natural Fiber-Reinforced Composites From Waste Materials, Israel Alejandro Carrete

Open Access Theses & Dissertations

Unprecedented levels of production and consumption have caused a rapid exhaustion of the Earth's virgin resources, which is coupled with a fast accumulation of contaminants in the form of solid waste, especially in landfills. Two significant landfill constituents come from textile waste and discarded plastic bottles. Since there is a finite amount of space that can be feasibly used for landfills, solutions that make use of these post-consumer products are imperative. This study presents one possible solution by using surface modifications of cotton fibers to produce a natural fiber-reinforced polymer composite (NFRPC) from post-consumer textile waste and polyethylene terephthalate ...


Direct Write 3d Printing Of Functional Ceramics, Jorge Angel Diaz 2019 University of Texas at El Paso

Direct Write 3d Printing Of Functional Ceramics, Jorge Angel Diaz

Open Access Theses & Dissertations

Humidity sensors are used in many industries and are important for ensuring quality and safety. Ceramic sensors are preferred because of their quick response time, ability to withstand high temperatures and excellent Chemical and mechanical stability. The manufacturing world has been moving toward additive manufacturing which is a form of synthesizing 3D tangible layer by layer in witch minimal waste is produced. Additive manufacturing also is known as 3D printing has opened new possibilities to design engineers by giving them design freedom and access to the layers of a part to allow embedded sensors. There is a category of ceramics ...


Understanding Of Deformation And Fracture Behavior In Next Generation High Strength-High Ductility Steels, Venkata Sai Yashwanth Injeti 2019 University of Texas at El Paso

Understanding Of Deformation And Fracture Behavior In Next Generation High Strength-High Ductility Steels, Venkata Sai Yashwanth Injeti

Open Access Theses & Dissertations

The industrial demand for low density high strength steels without compromising on ductility in is endless. In this regards, grain refinement and austenitic stability considered to the practical approach in order to meet the needs. The concept of phase reversion involving sever cold deformation of metastable austenite to generate strain-induced martensite, followed by time-temperature annealing sequence, was used to obtain varying grain size from nanograined/ultrafine-grained (NG/UFG) to coarse-grained (CG) regime. This concept was used to obtain "high strength-high ductility" combination in nano/ultrafine-grained (NG/UFG) austenite stainless steel. Using this concept, the objective of the study here is ...


Computational Studies On Perovskite-Metallofullerene Interface And Magnetic Properties Of Mn-Based Mixed Olivines, Bethuel Omutiti Khamala 2019 University of Texas at El Paso

Computational Studies On Perovskite-Metallofullerene Interface And Magnetic Properties Of Mn-Based Mixed Olivines, Bethuel Omutiti Khamala

Open Access Theses & Dissertations

Methyl ammonium lead halide (MAPbX3) perovskite based solar cells have recently emerged as promising class of materials for photovoltaic applications with efficiencies reaching over 22%. Designing interfaces with strong binding is vital to developing efficient, high-performing solar cells. Fullerene-based materials are widely employed as efficient electron acceptors and can serve as electron transporting layer in perovskite based solar cells. We have studied interfaces of methyl ammonium lead iodide MAPbI3 with Sc3N@C80 fullerene and Sc3N@C80PCBM fullerene derivate within the density functional formalism. Different surface terminations and orientations of the methyl ammonium are examined for binding of the fullerene layer ...


Reliability Estimation Of Reciprocating Seals Based On Multivariate Dependence Analysis And It's Experimental Validation, Chao Zhang, Rentong Chen, Shaoping Wang, Yujie Qian, Mileta M. Tomovic 2019 Old Dominion University

Reliability Estimation Of Reciprocating Seals Based On Multivariate Dependence Analysis And It's Experimental Validation, Chao Zhang, Rentong Chen, Shaoping Wang, Yujie Qian, Mileta M. Tomovic

Engineering Technology Faculty Publications

Accurate reliability estimation for reciprocating seals is of great significance due to their wide use in numerous engineering applications. This work proposes a reliability estimation method for reciprocating seals based on multivariate dependence analysis of different performance indicators. Degradation behavior corresponding to each performance indicator is first described by the Wiener process. Dependence among different performance indicators is then captured using D-vine copula, and a weight-based copula selection method is utilized to determine the optimal bivariate copula for each dependence relationship. A two-stage Bayesian method is used to estimate the parameters in the proposed model. Finally, a reciprocating seal degradation ...


A Sensorless Force-Feedback System For Robot-Assisted Laparoscopic Surgery, Baoliang Zhao, Carl A. Nelson 2019 Chinese Academy of Sciences

A Sensorless Force-Feedback System For Robot-Assisted Laparoscopic Surgery, Baoliang Zhao, Carl A. Nelson

Mechanical & Materials Engineering Faculty Publications

The existing surgical robots for laparoscopic surgery offer no or limited force feedback, and there are many problems for the traditional sensor-based solutions. This paper builds a teleoperation surgical system and validates the effectiveness of sensorless force feedback. The tool-tissue interaction force at the surgical grasper tip is estimated using the driving motor’s current, and fed back to the master robot with a position-force bilateral control algorithm. The stiffness differentiation experiment and tumor detection experiment were conducted. In the stiffness differentiation experiment, 43 out of 45 pairs of ranking relationships were identified correctly, yielding a success rate of 96 ...


Glocal Integrity In 420 Stainless Steel By Asynchronous Laser Processing, Michael P. Sealy, Haitham Hadidi, Cody Kanger, X. L. Yan, Bai Cui, J. A. McGeough 2019 University of Nebraska-Lincoln

Glocal Integrity In 420 Stainless Steel By Asynchronous Laser Processing, Michael P. Sealy, Haitham Hadidi, Cody Kanger, X. L. Yan, Bai Cui, J. A. Mcgeough

Mechanical & Materials Engineering Faculty Publications

Cold working individual layers during additive manufacturing (AM) by mechanical surface treatments, such as peening, effectively “prints” an aggregate surface integrity that is referred to as a glocal (i.e., local with global implications) integrity. Printing a complex, pre-designed glocal integrity throughout the build volume is a feasible approach to improve functional performance while mitigating distortion. However, coupling peening with AM introduces new manufacturing challenges, namely thermal cancellation, whereby heat relaxes favorable residual stresses and work hardening when printing on a peened layer. Thus, this work investigates glocal integrity formation from cyclically coupling LENS® with laser peening on 420 stainless ...


Deep Learning For Human Engineered Systems: Weak Supervision, Interpretability And Knowledge Embedding, Sambuddha Ghosal 2019 Iowa State University

Deep Learning For Human Engineered Systems: Weak Supervision, Interpretability And Knowledge Embedding, Sambuddha Ghosal

Graduate Theses and Dissertations

Pattern recognition has its origins in engineering while machine learning developed from computer science. Today, artificial intelligence (AI) is a booming field with many practical applications and active research topics that deals with both pattern recognition and machine learning. We now use software and applications to automate routine labor, understand speech (using Natural Language Processing) or images (extracting hierarchical features and patterns for object detection and pattern recognition), make diagnoses in medicine, even intricate surgical procedures and support basic scientific research.

This thesis deals with exploring the application of a specific branch of AI, or a specific tool, Deep Learning ...


An Investigation Of An Ionic Liquid Analog To The Conventional Metal-Oxide-Semiconductor Field-Effect Transistor, Richard Effler 2019 Iowa State University

An Investigation Of An Ionic Liquid Analog To The Conventional Metal-Oxide-Semiconductor Field-Effect Transistor, Richard Effler

Graduate Theses and Dissertations

An ionic circuit analogous to a traditional metal-oxide semiconductor was investigated, using 1-ethyl-3-methylimidazolium trifluoromethanesulfonate as the ionic liquid in the gating element. The circuit was observed to perform with comparatively high threshold and overdrive voltages in a region below the saturation current of the transistor. The concept of the design was successfully verified, although further improvements in electrode positioning and manufacturing precision are warranted.


Self-Powered Ghz Solution-Processed Hybrid Perovskite Photodetectors, Jinsong Huang 2019 Lincoln, NE

Self-Powered Ghz Solution-Processed Hybrid Perovskite Photodetectors, Jinsong Huang

Mechanical & Materials Engineering Faculty Publications

Organic-inorganic hybrid perovskite (OIHP) based photo-responsive devices include an OIHP active layer disposed between a cathode layer and an anode layer, and an electron extraction layer disposed between the cathode layer and the active layer. The electron extraction layer includes a layer of C60 directly disposed on the active layer. The active layer includes an organometal trihalide perovskite layer (e.g., CH3NH3PbI2X, where X includes at least one of Cl, Br, or I).


Insulating Tunneling Contact For Efficient And Stable Perovskite Solar Cells, Jinsong Huang, Xiaopeng Zheng, Qi Wang, Yang Bai, Qingfeng Dong 2019 Lincoln, NE

Insulating Tunneling Contact For Efficient And Stable Perovskite Solar Cells, Jinsong Huang, Xiaopeng Zheng, Qi Wang, Yang Bai, Qingfeng Dong

Mechanical & Materials Engineering Faculty Publications

Perovskite-based photoactive devices, such as solar cells, include an insulating tunneling layer inserted between the perovskite photoactive material and the electron collection layer to reduce charge recombination and concomitantly provide water resistant properties to the device.


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