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Characterization Of Landslide Processes From Radar Remote Sensing And Hydromechanical Modeling, Yuankun Xu 2021 Southern Methodist University

Characterization Of Landslide Processes From Radar Remote Sensing And Hydromechanical Modeling, Yuankun Xu

Earth Sciences Theses and Dissertations

Landsides are a natural geomorphic process yet a dangerous hazard which annually causes thousands of casualties and billions of property loss in a global scale. Understanding landslide motion kinematics from early initiation to final deposition is critical for monitoring, assessing, and forecasting landslide movement in order to mitigate their hazards. Landslides occur under diverse environmental settings and appear in variable types; however, all types of landslides can be mechanically attributed to shearing failure at the basal surface due to stress regime shift contributed by internal and/or external forcing. Typical internal factors include soil/rock weathering, whereas typical external triggering ...


Effect Of Developer Temperature On Photoresist Contrast In Grayscale Lithography, Dale Farnan, George Patrick Watson 2021 Singh Center for Nanotechnology

Effect Of Developer Temperature On Photoresist Contrast In Grayscale Lithography, Dale Farnan, George Patrick Watson

Protocols and Reports

SPR 220-3 photoresist was spin-coated onto a silicon wafer, exposed using a Heidelberg DWL66+ laserwriter at different laser powers, and developed at different temperatures. The effect of developer temperature on photoresist contrast was examined. Results show that increasing developer temperature decreased photoresist contrast and increased required dose.


Influence Of Parameters Of Non-Standard Modes Of Heat Treatment On Increasing The Wear Resistance Of Steel Products, Dorob Murotovich Berdiyev DSn, Abdulaziz Abdullajanovich Yusupov head teacher, Ravshan Kobilovich Tashmatov doctoral student, Tuychi Nemat ogli Ibodullayev assistant, Kabira Erkinovna Qurbonova head teacher 2021 ashkent state technical University, the department “Metal Forming”

Influence Of Parameters Of Non-Standard Modes Of Heat Treatment On Increasing The Wear Resistance Of Steel Products, Dorob Murotovich Berdiyev Dsn, Abdulaziz Abdullajanovich Yusupov Head Teacher, Ravshan Kobilovich Tashmatov Doctoral Student, Tuychi Nemat Ogli Ibodullayev Assistant, Kabira Erkinovna Qurbonova Head Teacher

Scientific-technical journal

The use of non-standard modes of heat treatment increases the density of dislocations in the crystal structure of the α-phase and increases the wear resistance of carbon, low-alloy steels under various friction conditions, which is comparable to the results when heated to a standard temperature (Ac3+30÷50 °C). The preliminary extreme heating temperature is determined. After re-quenching at standard temperature and low tempering, the wear resistance of steels under various types of friction increases by up to 40 % compared to standard quenching.


Monitoring Impact Damage In Composites With Large Area Sensing Skins, Alexander B. Vereen, Austin Downey, Subramani Sockalingham, Paul Ziehl, Simon Laflamme, Jian Li, Hongki Jo 2021 University of South Carolina

Monitoring Impact Damage In Composites With Large Area Sensing Skins, Alexander B. Vereen, Austin Downey, Subramani Sockalingham, Paul Ziehl, Simon Laflamme, Jian Li, Hongki Jo

Civil, Construction and Environmental Engineering Conference Presentations and Proceedings

The effect of low energy impacts can seriously impair the operational life span of composites in the field. These low-energy impacts can induce a permanent loss in the toughness of the composite without any visible indication of the material’s compromise. The detection of this damage utilizing nondestructive inspection requires dense measurements over much of the surface and has been traditionally achieved by removing the part from service for advanced imaging techniques. While these methods can accurately diagnose the damage inflicted internally by the impacts, they accrue non-trivial opportunity costs while the structure is inspected. To enable the capabilities of ...


A Single-Stage Passive Vibration Isolation System For Scanning Tunneling Microscopy, Toan T. Le 2021 California Polytechnic State University, San Luis Obispo

A Single-Stage Passive Vibration Isolation System For Scanning Tunneling Microscopy, Toan T. Le

Master's Theses

Scanning Tunneling Microscopy (STM) uses quantum tunneling effect to study the surfaces of materials on an atomic scale. Since the probe of the microscope is on the order of nanometers away from the surface, the device is prone to noises due to vibrations from the surroundings. To minimize the random noises and floor vibrations, passive vibration isolation is a commonly used technique due to its low cost and simpler design compared to active vibration isolation, especially when the entire vibration isolation system (VIS) stays inside an Ultra High Vacuum (UHV) environment. This research aims to analyze and build a single-stage ...


Optimization Of Bilayer Lift-Off Process To Enable The Gap Size Of 1Μm Using Lor 3a And S1813, Yeonjoon Suh, George Patrick Watson 2021 Singh Center for Nanotechnology

Optimization Of Bilayer Lift-Off Process To Enable The Gap Size Of 1Μm Using Lor 3a And S1813, Yeonjoon Suh, George Patrick Watson

Protocols and Reports

Bilayer lift-off process for 1μm feature size is demonstrated using LOR 3A and S1813 photoresist. The thickness of photoresists was fixed, whereas development time is varied. The process was further investigated by measuring the undercut depth and undercut rate by scanning electron microscopy. An optimized and reproducible recipe is provided.


A Typology For Magnetic Field Generator Technologies, N. Robert Y. Bouda, N. Prabhu Gaunkar, W. Shen Theh, Mani Mina 2021 Iowa State University

A Typology For Magnetic Field Generator Technologies, N. Robert Y. Bouda, N. Prabhu Gaunkar, W. Shen Theh, Mani Mina

Industrial Design Publications

This paper identifies different methodologies used to design suitable magnetic field generators (MFG) with adjustable characteristics. Variations in parameters, such as pulse frequency and amplitude elicit distinct responses. Assessing the differences between design parameters and experimental observations of magnetic field generators is essential for various applications. The use of magnetic field generator-based techniques is first studied in applications related to optical transmission, transcranial magnetic stimulation devices and magnetic resonance. Decades of research and technological advancement are associated with these methods. The associated nomenclature for describing and characterizing these methods are introduced and discussed. Finally, the paper presents possible future framework ...


Nondestructive Evaluation Of Aluminium Foam Panels Subjected To Impact Loading, Gabriella Epasto, Fabio Distefano, Hozhabar Mozafari, Emanoil Linul, Vincenzo Crupi 2021 University of Messina

Nondestructive Evaluation Of Aluminium Foam Panels Subjected To Impact Loading, Gabriella Epasto, Fabio Distefano, Hozhabar Mozafari, Emanoil Linul, Vincenzo Crupi

Mechanical & Materials Engineering Faculty Publications

Aluminium foam sandwich structures have excellent energy absorption capacity, combined with good mechanical properties and low density. Some of the authors of this paper proposed an innovative Metallic Foam Shell protective device against flying ballast impact damage in railway axles. A closed-cell aluminium foam was chosen for the Metallic Foam Shell device. The main goal of this study was the experimental investigation of the impact responses of aluminium foam panels. Low velocity impact tests were carried out at different energies on different types of aluminium foam panels in order to investigate the effects of some parameters, such as core thickness ...


Metallic Surface Doping Of Metal Halide Perovskites, Yuze Lin, Yuchuan Shao, Jun Dai, Tao Li, Yi Liu, Xuezeng Dai, Xun Xiao, Yehao Deng, Alexei Gruverman, Xiao Cheng Zeng, Jinsong Huang 2021 University of North Carolina

Metallic Surface Doping Of Metal Halide Perovskites, Yuze Lin, Yuchuan Shao, Jun Dai, Tao Li, Yi Liu, Xuezeng Dai, Xun Xiao, Yehao Deng, Alexei Gruverman, Xiao Cheng Zeng, Jinsong Huang

Mechanical & Materials Engineering Faculty Publications

Intentional doping is the core of semiconductor technologies to tune electrical and optical properties of semiconductors for electronic devices, however, it has shown to be a grand challenge for halide perovskites. Here, we show that some metal ions, such as silver, strontium, cerium ions, which exist in the precursors of halide perovskites as impurities, can n-dope the surface of perovskites from being intrinsic to metallic. The low solubility of these ions in halide perovskite crystals excludes the metal impurities to perovskite surfaces, leaving the interior of perovskite crystals intrinsic. Computation shows these metal ions introduce many electronic states close to ...


Surface Strengthening Of Single-Crystal Alumina By High-Temperature Laser Shock Peening, Fei Wang, X. L. Yan, Lei Liu, Michael Nastasi, Yongfeng Lu, Bai Cui 2021 University of Nebraska-Lincoln

Surface Strengthening Of Single-Crystal Alumina By High-Temperature Laser Shock Peening, Fei Wang, X. L. Yan, Lei Liu, Michael Nastasi, Yongfeng Lu, Bai Cui

Mechanical & Materials Engineering Faculty Publications

This manuscript reports a novel process of high-temperature laser shock peening (HTLSP) for surface strengthening of single-crystal ceramics such as sapphire and reveals its fundamental mechanisms. HTLSP at 1200°C can induce a high compressive residual stress on the surface of sapphire while minimize the damage of laser-driven shock waves. Transmission electron microscopy characteriza- tions revealed high dislocation densities near the surface, suggesting that plastic deformation at an ultrahigh strain rate was generated by the high shock wave pressure. The HTLSP-induced compres- sive residual stress can significantly improve the hardness and fracture toughness of sapphire, while maintain its outstanding optical ...


Process-Structure Relationship In The Directed Energy Deposition Of Cobalt-Chromium Alloy (Stellite 21) Coatings, Ziyad M. Smoqi, Joshua Toddy, Harold (Scott) Halliday, Jeffrey E. Shield, Prahalada K. Rao 2021 University of Nebraska-Lincoln

Process-Structure Relationship In The Directed Energy Deposition Of Cobalt-Chromium Alloy (Stellite 21) Coatings, Ziyad M. Smoqi, Joshua Toddy, Harold (Scott) Halliday, Jeffrey E. Shield, Prahalada K. Rao

Mechanical & Materials Engineering Faculty Publications

In this work, we accomplished the crack-free directed energy deposition (DED) of a multi-layer Cobalt- Chromium alloy coating (Stellite 21) on Inconel 718 substrate. Stellite alloys are used as coating materials given their resistance to wear, corrosion, and high temperature. The main challenge in DED of Stellite coatings is the proclivity for crack formation during printing. The objective of this work is to characterize the effect of the input energy density and localized laser-based preheating on the characteristics of the deposited coating, namely, crack formation, microstructural evolution, dilution of the coating composition due to diffusion of iron and nickel from ...


The Role Of Microenvironmental Cues And Mechanical Loading Milieus In Breast Cancer Cell Progression And Metastasis, Brandon D. Riehl, Eunju Kim, Tasneem Bouzid, Jung Yul Lim 2021 University of Nebraska-Lincoln

The Role Of Microenvironmental Cues And Mechanical Loading Milieus In Breast Cancer Cell Progression And Metastasis, Brandon D. Riehl, Eunju Kim, Tasneem Bouzid, Jung Yul Lim

Mechanical & Materials Engineering Faculty Publications

Cancer can disrupt the microenvironments and mechanical homeostatic actions in multiple scales from large tissue modification to altered cellular signaling pathway in mechanotransduction. In this review, we highlight recent progresses in breast cancer cell mechanobiology focusing on cell-microenvironment interaction and mechanical loading regulation of cells. First, the effects of microenvironmental cues on breast cancer cell progression and metastasis will be reviewed with respect to substrate stiffness, chemical/topographic substrate patterning, and 2D vs. 3D cultures. Then, the role of mechanical loading situations such as tensile stretch, compression, and flow-induced shear will be discussed in relation to breast cancer cell mechanobiology ...


Application Of Laser Assisted Ultrasonic Nanocrystal Surface Modification On Aluminum And 3d Printed Titanium, Eman Hassan, Thomas Crouse 2021 The University of Akron

Application Of Laser Assisted Ultrasonic Nanocrystal Surface Modification On Aluminum And 3d Printed Titanium, Eman Hassan, Thomas Crouse

Williams Honors College, Honors Research Projects

A novel surface treatment, laser assisted ultrasonic nanocrystal surface modification (LA-UNSM), has proved effective in increasing surface hardness, and fatigue life. The objective of this research is to determine the effectiveness of this process on components created with additive manufacturing. To accomplish this, we investigated the effectiveness of LA-UNSM treatment on aluminum, a common 3d printed metal, and the effectiveness of LA-UNSM processing on 3d printed titanium. We first conducted our own literature review to assess the practicality of using this same treatment on aluminum. We then treated traditionally manufactured aluminum at varying levels of laser intensity to determine if ...


Hyperbolic Quadrature Method Of Moments For The One-Dimensional Kinetic Equation, Rodney O. Fox, Frédérique Laurent 2021 Iowa State University

Hyperbolic Quadrature Method Of Moments For The One-Dimensional Kinetic Equation, Rodney O. Fox, Frédérique Laurent

Chemical and Biological Engineering Publications

A solution is proposed to a longstanding open problem in kinetic theory, namely, 5 given any set of realizable velocity moments up to order 2n, a closure for the moment of order 2n+1 is 6 constructed for which the moment system found from the free-transport term in the one-dimensional 7 (1-D) kinetic equation is globally hyperbolic and in conservative form. In prior work, the hyperbolic 8 quadrature method of moments (HyQMOM) was introduced to close this moment system up to fourth 9 order (n ≤ 2). Here, HyQMOM is reformulated and extended to arbitrary even-order moments. The 10 HyQMOM closure ...


Comparison Of Additively Manufactured And Wrought 17-4 Ph Stainless Steels In Ultra Low Cycle Fatigue, Timothy Strasser 2020 University of Arkansas, Fayetteville

Comparison Of Additively Manufactured And Wrought 17-4 Ph Stainless Steels In Ultra Low Cycle Fatigue, Timothy Strasser

Theses and Dissertations

Additive manufacturing (AM) processes allow for creation of complex geometries that are otherwise impractical to fabricate with traditional subtractive methods. AM technology has potential to improve the optimization of seismic lateral force resisting components which dissipate seismic energy through large plastic strains; however, the ultra low-cycle fatigue performance of AM metals are not yet well understood. Void formation during the AM fabrication process has potential to affect performance. This study compares the performance of heat-treated and non-heat-treated AM and wrought 17-4PH stainless steel in Ultra Low Cycle Fatigue. To understand ULCF performance differences between the AM and wrought specimens, post ...


Leveraging Biomimicry And Additive Manufacturing To Improve Load Transfer In Brittle Materials, Ana Paula Bernardo 2020 University of Arkansas, Fayetteville

Leveraging Biomimicry And Additive Manufacturing To Improve Load Transfer In Brittle Materials, Ana Paula Bernardo

Theses and Dissertations

With the emergence of Additive Manufacturing (i.e., 3D printing) in construction, new strategically designed shapes can be created to improve load transfer through structural members and foundations. Cross-sections can be optimized to carry load using less material, or even using weaker constituent materials, like soils, which are cheap and abundant. The goal of this research is to investigate the benefits of using cellular patterns which leverage biomimicry in civil engineering applications, since nature has perfectly engineered materials and patterns which carry loads with the least amount of material possible. Most of the periodic cellular work to date has focused ...


Experimental And Computational Analysis Of Progressive Failure In Bolted Hybrid Composite Joints, John S. Brewer 2020 Air Force Institute of Technology

Experimental And Computational Analysis Of Progressive Failure In Bolted Hybrid Composite Joints, John S. Brewer

Theses and Dissertations

Composite materials are strong, lightweight, and stiff making them desirable in aerospace applications. However, a practical issue arises with composites in that they behave unpredictably in bolted joints, where damage and cracks are often initiated. This research investigated a solution to correcting the problem with composite bolted joints. A novel hybrid composite material was developed, where thin stainless steel foils were placed between and in place of preimpregnated composite plies during the cure cycle to reinforce stress concentrations in bolted joints. This novel composite was compared to control samples experimentally in quasi-static monotonic loading in double shear configuration in 9-ply ...


A Hyperbolic Two-Fluid Model For Compressible Flows With Arbitrary Material-Density Ratios, Rodney O. Fox, Frédérique Laurent, Aymeric Vié 2020 Iowa State University and Fédération de Mathématiques de CentraleSupélec, CNRS

A Hyperbolic Two-Fluid Model For Compressible Flows With Arbitrary Material-Density Ratios, Rodney O. Fox, Frédérique Laurent, Aymeric Vié

Chemical and Biological Engineering Publications

A hyperbolic two-fluid model for gas–particle flow derived using the Boltzmann–Enskog kinetic theory is generalized to include added mass. In place of the virtual-mass force, to guarantee indifference to an accelerating frame of reference, the added mass is included in the mass, momentum and energy balances for the particle phase, augmented to include the portion of the particle wake moving with the particle velocity. The resulting compressible two-fluid model contains seven balance equations (mass, momentum and energy for each phase, plus added mass) and employs a stiffened-gas model for the equation of state for the fluid. Using Sturm ...


Transformation Between Polar And Rectangular Coordinates Of Stiffness And Dampness Parameters In Hydrodynamic Journal Bearings, Zhuxin TIAN, Yu HUANG 2020 School of Mechanical Engineering, Hubei University of Arts and Science, Xiangyang 441053, China

Transformation Between Polar And Rectangular Coordinates Of Stiffness And Dampness Parameters In Hydrodynamic Journal Bearings, Zhuxin Tian, Yu Huang

Friction

The stiffness and dampness parameters of journal bearings are required in rectangular coordinates for analyzing the stability boundary and threshold speed of oil film bearings. On solving the Reynolds equation, the oil film force is always obtained in polar coordinates; thus, the stiffness and dampness parameters can be easily obtained in polar coordinates. Therefore, the transformation between the polar and rectangular coordinates of journal bearing stiffness and dampness parameters is discussed in this study.


A Finite Element Analysis (Fea) Approach To Simulate The Coefficient Of Friction Of A Brake System Starting From Material Friction Characterization, Gabriele RIVA, Francesco VARRIALE, Jens WAHLSTRÖM 2020 Brembo S.p.A., Stezzano (BG), Stezzano (BG) 24040, Italy

A Finite Element Analysis (Fea) Approach To Simulate The Coefficient Of Friction Of A Brake System Starting From Material Friction Characterization, Gabriele Riva, Francesco Varriale, Jens Wahlström

Friction

The coefficient of friction (COF) is one of the most important parameters to evaluate the performance of a brake system. To design proper brake systems, it is important to know the COF when estimating the brake force and resulting torque. It is challenging to simulate the COF since friction in disc brakes is a complex phenomenon that depends on several parameters such as sliding velocity, contact pressure, materials, and temperatures, etc. There is a lack of studies found in the literature focusing on simulation of the COF for a full brake system based on tribometer material characterization. The aim of ...


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