Hierarchical Structure And Material Integration For Electrocatalytic Co2 Reduction,
2022
University of Arkansas, Fayetteville
Hierarchical Structure And Material Integration For Electrocatalytic Co2 Reduction, Hamed Mehrabi
Graduate Theses and Dissertations
CO2 released by the combustion of fossil fuels is driving significant changes to the earth’sclimate. The natural cycle for removing CO2 from the atmosphere, namely photosynthesis, cannot keep up with the rate at which it is being added. Developing engineering approaches to remove CO2 from the atmosphere is becoming essential to reduce these effects. Removal leads to further issues of carbon sequestration and favorable CO2 reuse strategies, including the electrochemical transformation of recovered CO2 to useful products such as fuels and materials. Copper is an important electrocatalyst for the CO2 reduction reaction (CO2RR) because of its unique capability for producing …
A Comparative Evaluation Of Oxidation And Combustion Phenomena In Ti-6al-4v Exposed To Earth Re-Entry And Arc-Jet Test Environments,
2022
University of Texas at El Paso
A Comparative Evaluation Of Oxidation And Combustion Phenomena In Ti-6al-4v Exposed To Earth Re-Entry And Arc-Jet Test Environments, Arlene Smith
Open Access Theses & Dissertations
The Ti-6Al-4V alloy is widely used in aerospace applications for its beneficial combination of properties. However, this alloy has high solubility for oxygen and thus a high reactivity. Recovered data contained within the Columbia artifacts suggests that this alloy underwent an accelerated degradation and combustion reaction when exposed to the high enthalpy, low-pressure surroundings experienced during reentry into Earth's atmosphere. Arc-jet testing has provided a simulated aerothermodynamic heating environment to mimic what the spacecraft endured. When the effect of thermal alteration on this alpha-beta phase alloy was investigated during previous studies, optical metallography and microhardness tests revealed inconsistencies between samples …
An Application Of Optimized Bistable Laminates As A Low Velocity, Low Impact Mechanical Deterrent,
2022
Clemson University
An Application Of Optimized Bistable Laminates As A Low Velocity, Low Impact Mechanical Deterrent, Graham Lancaster
All Theses
This research considers the problem of using bistable laminates as a mechanical deterrent to the impending impact of a particle. The structure will be controlled through an algorithm that will utilize piezoelectric devices to activate them in unison with the bistable laminate to successfully deter. A novel experimental setup will be constructed to ensure that the bistable laminate stays fixed when acting as a mechanical deterrent. Piezoelectricity is the main driving force of the bistable laminate to morph and this study will use a Macro Fiber Composite (MFC) actuator that contains piezoelectric ceramic rods in a patch to transfer electrical …
Dynamic Perimeter Movement Using Uavs And Robotic Systems,
2022
Kennesaw State University
Dynamic Perimeter Movement Using Uavs And Robotic Systems, Nayeli Barrett, John Lawson, Billy Kihei
Symposium of Student Scholars
For this study, we propose a Dynamic Perimeter Movement system that has a user-operated UAV to identify GPS coordinate points using land markers such as April Tags. These markers would be used to identify the perimeter of a road work zone. Once the work zone is determined, autonomous robotic traffic cones would disperse to position themselves around the perimeter determined by coordinate points. As the work zone progresses the UAV would periodically update the perimeter to reposition robotic traffic cones. These traffic cones will operate using a Pure Pursuit system as a means to navigate.
Efects Of Non‑Newtonian Viscosity
On Arterial And Venous Fow
And Transport,
2022
University of Michigan
Efects Of Non‑Newtonian Viscosity On Arterial And Venous Fow And Transport, Sabrina Lynch, Nitesh Nama, C Alberto Figueroa
Mechanical & Materials Engineering Faculty Publications
It is well known that blood exhibits non-Newtonian viscosity, but it is generally modeled as a Newtonian fluid. However, in situations of low shear rate, the validity of the Newtonian assumption is questionable. In this study, we investigated differences between Newtonian and non-Newtonian hemodynamic metrics such as velocity, vorticity, and wall shear stress. In addition, we investigated cardiovascular transport using two different approaches, Eulerian mass transport and Lagrangian particle tracking. Non-Newtonian solutions revealed important differences in both hemodynamic and transport metrics relative to the Newtonian model. Most notably for the hemodynamic metrics, in-plane velocity and vorticity were consistently larger in …
Near-Ir Laser Ablation Of Simulated Radiologically Contaminated Oxides On Carbon Steel Feeder Pipes,
2022
The University of Western Ontario
Near-Ir Laser Ablation Of Simulated Radiologically Contaminated Oxides On Carbon Steel Feeder Pipes, Thao Viet Do
Electronic Thesis and Dissertation Repository
As nuclear power plants age and retire from service, many countries face significant challenges concerning the safe long-term storage and disposal of large volumes of low and intermediate level radioactive wastes (L&ILW). The volumes of metallic waste are of particular concern, as when metal corrodes it produces hydrogen that could lead to pressure build-up in interim storage and disposal. In Canada, a significant fraction of the metallic wastes for Canada Deuterium Uranium (CANDU) nuclear reactors are out-of-core reactor components, such as carbon steel (CS) feeder pipes. The radioactive contamination is expected to be largely confined to the surface oxide layers …
Enhanced Electron Correlation And Significantly Suppressed
Thermal Conductivity In Dirac Nodal-Line Metal Nanowires
By Chemical Doping,
2022
Indiana University
Enhanced Electron Correlation And Significantly Suppressed Thermal Conductivity In Dirac Nodal-Line Metal Nanowires By Chemical Doping, Amanda L. Coughlin, Zhiliang Pan, Jeonghoon Hong, Tongxie Zhang, Xun Zhan, Wenqian Wu, Dongyue Xie, Tian Tong, Thomas Ruch, Jean J. Heremans, Jiming Bao, Herbert A. Fertig, Jian Wang, Jeongwoo Kim, Hanyu Zhu, Deyu Li, Shixiong Zhang
Mechanical & Materials Engineering Faculty Publications
Enhancing electron correlation in a weakly interacting topological system has great potential to promote correlated topological states of matter with extraordinary quantum properties. Here, the enhancement of electron correlation in a prototypical topological metal, namely iridium dioxide (IrO2), via doping with 3d transition metal vanadium is demonstrated. Single-crystalline vanadium-doped IrO2 nanowires are synthesized through chemical vapor deposition where the nanowire yield and morphology are improved by creating rough surfaces on substrates. Vanadium doping leads to a dramatic decrease in Raman intensity without notable peak broadening, signifying the enhancement of electron correlation. The enhanced electron correlation is further …
Exosomes Derived From Differentiated Human Admsc With The Schwann
Cell Phenotype Modulate Peripheral Nerve-Related Cellular Functions,
2022
University of Nebraska Medical Center
Exosomes Derived From Differentiated Human Admsc With The Schwann Cell Phenotype Modulate Peripheral Nerve-Related Cellular Functions, Bo Liu, Yunfan Kong, Wen Shi, Mitchell Kuss, Ke Liao, Guoku Hu, Peng Xiao, Jagadesan Sankarasubramanian, Chittibabu Guda, Xinglong Wang, Yuguo Lei, Bin Duan
Mechanical & Materials Engineering Faculty Publications
Peripheral nerve regeneration remains a significant clinical challenge due to the unsatisfactory functional recovery and public health burden. Exosomes, especially those derived from mesenchymal stem cells (MSCs), are promising as potential cell-free therapeutics and gene therapy vehicles for promoting neural regeneration. In this study, we reported the differentiation of human adipose derived MSCs (hADMSCs) towards the Schwann cell (SC) phenotype (hADMSC-SCs) and then isolated exosomes from hADMSCs with and without differentiation (i.e., dExo vs uExo). We assessed and compared the effects of uExo and dExo on antioxidative, angiogenic, antiinflammatory, and axon growth promoting properties by using various peripheral nerve-related cells. …
Designing And Cnc Machine Valve Sub-Plates And Quick Mounts For Hydraulic Power Training Systems,
2022
Morehead State University
Designing And Cnc Machine Valve Sub-Plates And Quick Mounts For Hydraulic Power Training Systems, Connor Maxam
Morehead State Theses and Dissertations
A thesis presented to the faculty of the College of Business and Technology at Morehead State University in partial fulfillment of the requirements for the Degree of Master of Science by Connor Maxam on November 22, 2022.
Phase Space Analysis Of Nonlinear Wave Propagation In A Bistable Mechanical
Metamaterial With A Defect,
2022
University of Nebraska-Lincoln
Phase Space Analysis Of Nonlinear Wave Propagation In A Bistable Mechanical Metamaterial With A Defect, Mohammed A. Mohammed, Piyush Grover
Mechanical & Materials Engineering Faculty Publications
We study the dynamics of solitary waves traveling in a one-dimensional chain of bistable elements in the presence of a local inhomogeneity (“defect”). Numerical simulations reveal that depending upon its initial speed, an incoming solitary wave can get transmitted, captured, or reflected upon interaction with the defect. The dynamics are dominated by energy exchange between the wave and a breather mode localized at the defect. We derive a reduced-order two degree of freedom Hamiltonian model for wave-breather interaction and analyze it using dynamical systems techniques. Lobe dynamics analysis reveals the fine structure of phase space that leads to the complicated …
Feedforward Control Of Thermal History In Laser Powder Bed Fusion:
Toward Physics-Based Optimization Of Processing Parameters,
2022
University of Nebraska - Lincoln
Feedforward Control Of Thermal History In Laser Powder Bed Fusion: Toward Physics-Based Optimization Of Processing Parameters, Alex Riensche, Benjamin D. Bevans, Ziyad M. Smoqi, Reza Yavari, Ajay Krishnan, Josie Gilligan, Nicholas Piercy, Kevin D. Cole, Prahalada K. Rao
Mechanical & Materials Engineering Faculty Publications
We developed and applied a model-driven feedforward control approach to mitigate thermal-induced flaw formation in laser powder bed fusion (LPBF) additive manufacturing process. The key idea was to avert heat buildup in a LPBF part before it is printed by adapting process parameters layer-by-layer based on insights from a physics-based thermal simulation model. The motivation being to replace cumbersome empirical build-and-test parameter optimization with a physics-guided strategy. The approach consisted of three steps: prediction, analysis, and correction. First, the temperature distribution of a part was predicted rapidly using a graph theory-based computational thermal model. Second, the model-derived thermal trends were …
Adiabatic Shear Banding In Nickel And Nickel-Based Superalloys: A Review,
2022
Air Force Institute of Technology
Adiabatic Shear Banding In Nickel And Nickel-Based Superalloys: A Review, Russell A. Rowe, Paul G. Allison, Anthony N. Palazotto, Keivan Davami
Faculty Publications
This review paper discusses the formation and propagation of adiabatic shear bands in nickel-based superalloys. The formation of adiabatic shear bands (ASBs) is a unique dynamic phenomenon that typically precedes catastrophic, unpredicted failure in many metals under impact or ballistic loading. ASBs are thin regions that undergo substantial plastic shear strain and material softening due to the thermo-mechanical instability induced by the competitive work hardening and thermal softening processes. Dynamic recrystallization of the material’s microstructure in the shear region can occur and encourages shear localization and the formation of ASBs. Phase transformations are also often seen in ASBs of ferrous …
The Design And Manufacturing Of An Environmental Chamber To Test Microelectronic Devices,
2022
Purdue University
The Design And Manufacturing Of An Environmental Chamber To Test Microelectronic Devices, William Graber, Aniket Roy Chowdhury
The Journal of Purdue Undergraduate Research
No abstract provided.
A Method Of Assessing Peripheral Stent Abrasiveness Under
Cyclic Deformations Experienced During Limb Movement,
2022
University of Nebraska-Lincoln
A Method Of Assessing Peripheral Stent Abrasiveness Under Cyclic Deformations Experienced During Limb Movement, Courtney Keiser, Kaspars Maleckis, Pauline Struczewska, Majid Jadidi, Jason N. Mactaggart, Alexey Kamenskiy
Mechanical & Materials Engineering Faculty Publications
Poor outcomes of peripheral arterial disease stenting are often attributed to the inability of stents to accommodate the complex biomechanics of the flexed lower limb. Abrasion damage caused by rubbing of the stent against the artery wall during limb movement plays a significant role in reconstruction failure but has not been characterized. Our goals were to develop a method of assessing the abrasiveness of peripheral nitinol stents and apply it to several commercial devices. Misago, AbsolutePro, Innova, Zilver, SmartControl, SmartFlex, and Supera stents were deployed inside electrospun nanofibrillar tubes with femoropopliteal artery-mimicking mechanical properties and subjected to cyclic axial compression …
Multi-Robot Symbolic Task And Motion Planning Leveraging Human Trust Models: Theory And Applications,
2022
Clemson University
Multi-Robot Symbolic Task And Motion Planning Leveraging Human Trust Models: Theory And Applications, Huanfei Zheng
All Dissertations
Multi-robot systems (MRS) can accomplish more complex tasks with two or more robots and have produced a broad set of applications. The presence of a human operator in an MRS can guarantee the safety of the task performing, but the human operators can be subject to heavier stress and cognitive workload in collaboration with the MRS than the single robot. It is significant for the MRS to have the provable correct task and motion planning solution for a complex task. That can reduce the human workload during supervising the task and improve the reliability of human-MRS collaboration. This dissertation relies …
Revealing The Pulse-Induced Electroplasticity
By Decoupling Electron Wind Force,
2022
Zhejiang University
Revealing The Pulse-Induced Electroplasticity By Decoupling Electron Wind Force, Xing Li, Qi Zhu, Youran Hong, He Zheng, Jian Wang, Jiangwei Wang, Ze Zhang
Mechanical & Materials Engineering Faculty Publications
Micro/nano electromechanical systems and nanodevices often suffer from degradation under electrical pulse. However, the origin of pulse-induced degradation remains an open question. Herein, we investigate the defect dynamics in Au nanocrystals under pulse conditions. By decoupling the electron wind force via a properly-designed in situ TEM electropulsing experiment, we reveal a non-directional migration of Σ3{112} incoherent twin boundary upon electropulsing, in contrast to the expected directional migration under electron wind force. Quantitative analyses demonstrate that such exceptional incoherent twin boundary migration is governed by the electron-dislocation interaction that enhances the atom vibration at dislocation cores, rather than driven by the …
Highly Efficient, Perfect, Large
Angular And Ultrawideband Solar
Energy Absorber For Uv To Mir
Range,
2022
Marwadi University
Highly Efficient, Perfect, Large Angular And Ultrawideband Solar Energy Absorber For Uv To Mir Range, Shobhit K. Patel, Arun Kumar Udayakumar, G. Mahendran, B. Vasudevan, Jaymit Surve, Juveriya Parmar
Mechanical & Materials Engineering Faculty Publications
Although different materials and designs have been tried in search of the ideal as well as ultrawideband light absorber, achieving ultra-broadband and robust unpolarized light absorption over a wide angular range has proven to be a major issue. Light-field regulation capabilities provided by optical metamaterials are a potential new technique for perfect absorbers. It is our goal to design and demonstrate an ultra-wideband solar absorber for the ultraviolet to a mid-infrared region that has an absorptivity of TE/TM light of 96.2% on average. In the visible, NIR, and MIR bands of the solar spectrum, the absorbed energy is determined to …
Finite Element-Based Machine Learning Model For Predicting
The Mechanical Properties Of Composite Hydrogels,
2022
Florida Institute of Technology
Finite Element-Based Machine Learning Model For Predicting The Mechanical Properties Of Composite Hydrogels, Yasin Shokrollahi, Pengfei Dong, Peshala T. Gamage, Nashaita Patrawalla, Vipuil Kishore, Hozhabr Mozafari, Linxia Gu
Mechanical & Materials Engineering Faculty Publications
In this study, a finite element (FE)-based machine learning model was developed to predict the mechanical properties of bioglass (BG)-collagen (COL) composite hydrogels. Based on the experimental observation of BG-COL composite hydrogels with scanning electron microscope, 2000 microstructural images with randomly distributed BG particles were created. The BG particles have diameters ranging from 0.5 μm to 1.5 μm and a volume fraction from 17% to 59%. FE simulations of tensile testing were performed for calculating the Young’s modulus and Poisson’s ratio of 2000 microstructures. The microstructural images and the calculated Young’s modulus and Poisson’s ratio by FE simulation were used …
Tuning The Mechanical Behavior Of Density-Graded Elastomeric Foam Structures Via Interlayer Properties.,
2022
Rowan University
Tuning The Mechanical Behavior Of Density-Graded Elastomeric Foam Structures Via Interlayer Properties., Kazi Z Uddin, Ibnaj A Anni, George Youssef, Behrad Koohbor
Henry M. Rowan College of Engineering Faculty Scholarship
The concept of density-graded foams has been proposed to simultaneously enhance strain energy dissipation and the load-bearing capacities at a reduced structural weight. From a practical perspective, the fabrication of density-graded foams is often achieved by stacking different foam densities. Under such conditions, the adhesive interlayer significantly affects the mechanical performance and failure modes of the structure. This work investigates the role of different adhesive layers on the mechanical and energy absorption behaviors of graded flexible foams with distinct density layers. Three adhesive candidates with different chemical, physical, and mechanical characteristics are used to assemble density-graded polyurea foam structures. The …
Large Refrigerant Capacity In Superparamagnetic
Iron Nanoparticles Embedded In A Thin Film
Matrix,
2022
North Carolina A&T State University
Large Refrigerant Capacity In Superparamagnetic Iron Nanoparticles Embedded In A Thin Film Matrix, Kaushik Sarkar, Surabhi Shaji, Jeffrey E. Shield, Christian H. Binek, Dhananjay Kumar
Mechanical & Materials Engineering Faculty Publications
A magnetocaloric effect (MCE) with sizable isothermal entropy change (ΔS) maintained over a broad range of temperatures above the blocking temperature is reported for a rare earth-free superparamagnetic nanoparticle system comprising of Fe–TiN heterostructure. Superparamagnetic iron (Fe) particles were embedded in a titanium nitride (TiN) thin film matrix in a TiN/Fe/TiN multilayered pattern using a pulsed laser deposition method. High angle annular dark-field images in conjunction with dispersive energy analysis, recorded using scanning transmission electron microscopy, show a clear presence of alternating layers of Fe and TiN with a distinct atomic number contrast between Fe particles and TiN. Quantitative information …
