Engineering Commons^™

Peridynamic Simulation Of Elastic Wave Propagation By Applying The Boundary Conditions With The Surface Node Method, Francesco Scabbia, Mirco Zaccariotto, Ugo Galvanetto, Florin Bobaru

Department of Mechanical and Materials Engineering: Faculty Publications

Peridynamics is a novel nonlocal theory able to deal with discontinuities, such as crack initiation and propagation. Near the boundaries, due to the incomplete nonlocal region, the peridynamic surface effect is present, and its reduction relies on using a very small horizon, which ends up being expensive computationally. Furthermore, the imposition of nonlocal boundary conditions in a local way is often required. The surface node method has been proposed to solve both the aforementioned issues, providing enhanced accuracy near the boundaries of the body. This method has been verified in the cases of quasi-static elastic problems and diffusion problems evolving …

A New Course In Defense Manufacturing – An Introduction To Shipbuilding, Alley C. Butler

Manufacturing & Industrial Engineering Faculty Publications

This paper discusses the development and deployment of a new course in DMEI (Defense Manufacturing Engineering Innovation) titled, “Introduction to Shipbuilding.” This course has been taught using Zoom since 2021 at both the University of Texas Rio Grande Valley, a Hispanic Serving Institution, and Virginia State University, a Historically Black University. After a brief literature review, an outline of the course is presented with topics including the maritime market for shipbuilding, economics of shipbuilding, the classification agencies, metallurgy and welding processes, ship structure and assembly, shipyard layout, accuracy control, and shipbuilding planning and scheduling. Difficulties in obtaining an appropriate textbook …

การศึกษาการตรวจหาเชื้อวัณโรคจากภาพย้อมสีทนกรดโดยใช้การเรียนรู้เชิงลึกด้วยเทคนิคการจำแนกและการตรวจจับวัตถุ, ธีริศรา มิคาระเศรษฐ์

Chulalongkorn University Theses and Dissertations (Chula ETD)

การศึกษานี้เป็นการวิเคราะห์ Deep Learning สำหรับตรวจหาเชื้อวัณโรคด้วยวิธีการ Modified Classification และ Object Detection โดยใช้ Pre-Trained Model คือ Enhanced ResNet50 และ AlexNet ในการวิเคราะห์ ซึ่งวิธี Modified Classification มีการนำ Image Processing มาประยุกต์ใช้กับการทดลอง เมื่อ Training ข้อมูล พบว่า ResNet50 เป็น Model ที่มีประสิทธิภาพสูงสุดได้ค่า Accuracy เท่ากับ 92.71% และ Precision เท่ากับ 92.7% เมื่อจัดกลุ่มใหม่สำหรับการวิเคราะห์ แบบ Suspected Positive Low Confidence และ Suspected Positive High Confidence ผลการทดลองพบว่า ResNet50 ยังคงมีประสิทธิภาพที่ดีที่สุด มีค่า Accuracy เท่ากับ 98.06% ค่า Precision เท่ากับ 98.59% ส่วน Suspected Positive High Confidence มีค่า Accuracy เท่ากับ 94.38% และค่า Precision เท่ากับ 91.41% และในการวิเคราะห์ Deep Learning วิธี Object Detection ได้ค่า Precision เท่ากับ 82.81% และ Mean AP เท่ากับ 36.79% จากการเปรียบเทียบการวิเคราะห์ทั้ง 2 Models พบว่า วิธีวิเคาระห์แบบ Modified Classification ได้ผลลัพทธ์ดีกว่า จึงนำไปตรวจร่วมกับวิธีการตรวจของแพทย์ (Doctor …

Utilisation Des Ponts Élévateurs De Véhicules Hors Terre À Deux Colonnes : Identification De Déterminants Techniques De Stabilité Et Des Déterminants Du Travail Des Techniciens Automobiles, Damien Burlet-Vienney, Sylvie Beaugrand, Bertrand Galy, Maud Gonella, François Gauthier, Élise Ledoux, Isabelle Berger, Isvieysys Armas Marrero, Kariane Cusson Bertrand

Rapports de recherche scientifique

Cette recherche porte spécifiquement sur l’utilisation des ponts élévateurs de véhicules (PEV) hors terre à deux colonnes (HT2C). Les PEV HT2C sont utilisés par les techniciens automobiles lors de l’entretien et de la réparation des véhicules et les amènent à travailler sous ou à proximité d’une charge surélevée de plusieurs tonnes. La mort d’un jeune technicien en 2014 est à l’origine d’une concertation du secteur de la réparation automobile et de ces travaux de recherche. La chute d’un véhicule d’un PEV HT2C est le risque ciblé par cette étude.

De nombreux facteurs sont susceptibles de contribuer à la chute d’un …

Thermal Performance And Fluid Flow Studies Of Twisted Tape Inserts Using Scaled Surrogate Fluids For Molten Salt Energy Applications, Arturo Cabral

Theses and Dissertations

Global energy consumption is expected to increase with population growth and innovative clean sources of energy are sought out that can help meet the needs of a continuously power-hungry world. Some of these innovative sources of energy use molten salts as their operating and cooling fluid, such as fission reactors, fusion reactors, and solar power with energy storage. Molten salts are considered due to their efficient heat transfer properties, thermal energy storage capabilities, and high operating temperatures. To expedite their deployment, a further understanding of the heat transfer systems is required to accurately design and develop the heat transfer components …

Advanced Modeling And Innovative Transcranial Magnetic Stimulation Coil Designs For The Treatment Of Neurological Disorders, Mohannad Tashli

Theses and Dissertations

Transcranial magnetic stimulation (TMS) is a safe, effective and non-invasive treatment for several mental and psychiatric disorders. TMS is an FDA approved treatment and is commonly applied to patients who do not respond to medications for the treatment of clinical depression, smoking cessation, obsessive-compulsive disorder and migraine. Recently, there has been an increase in the development of electromagnetic neuromodulation techniques targeted at enhancing the effectiveness of TMS devices for the treatment of mental diseases. In TMS stimulation, focality is an important factor which determines the specificity of the pulses induced in different brain tissues. The electromagnetic pulses must be confined …

Full Body Harness Design Modifications And Evaluation: A Senior Design Project, Martin Mead, Jordan Von Seggern

The Journal of Undergraduate Research

Full-body harness (FBH) is critical for the safe operation of industrial and recreational activities, from installing and maintaining infrastructure such as wind turbines to ziplining and mountaintop adventures. However, harness design remains in the proprietary information of companies with limited technical information available for improvements or readjustments to specialized applications. As the outcome of the Capstone project, the paper focuses on multiple technical aspects and the engineering processes for designing FBH for ziplining recreational users, from selecting and testing materials for operation in cold weather to improvements in design and manufacturing for user comfort. The project is guided by technical …

Quantifying The Effects Of Hvac Operation To Mitigate Aerosol Concentration In A Classroom Using Cfd, Scott Deprez

Electronic Theses and Dissertations

Heating, ventilation, and air conditioning (HVAC) is a complex mechanical system for the transition of air between outdoor and indoor areas. These systems are directly responsible for temperature, humidity, and air flow into any given space, thereby providing a level of comfort to those who live indoors. These systems account for 52 percent of U.S. energy consumption. When designing HVAC systems, indoor air quality (IAQ) is the main focus for achieving safe and clean air, such as in the case of airborne diseases. HVAC systems are responsible for the flow of air in indoor spaces and thereby expand the transmissible …

Efficacy, Durability And Design Of A Bucket Wheel Excavator For Icy Lunar Regolith, Austin Lohsandt

Electronic Theses and Dissertations

This research project focused on the design and testing of a prototype bucket wheel excavator developed for NASA's Break the Ice Lunar Challenge, which sought innovative ideas for lunar excavation. Several attempts have been made by other universities and private industries to create systems that can successfully excavate simulated frozen regolith, however, few have been successful. The chosen excavation technology employed a bucket wheel concept inspired by large open-pit mining machines, modified to incorporate grinding nubs for pulverizing lunar simulant material. The goals included proving the viability of a bucket wheel excavator for lunar excavation, exploring grinding nubs, conducting durability …

Mechanical Properties Evaluation Of 3d Printed Petg And Pctg Polymers, Kalpesh Krishnarao Bhosale

Electronic Theses and Dissertations

3D printing is also known as additive manufacturing (AM) which has become a popular manufacturing trend over the years. Due to its unique advantages of fast production rate, ability to create complex geometrical features, toolless manufacturing and many more attracts various industries from Aerospace to general cosmetics. Along with the advancement in material science, various polymers including Polylactic Acid (PLA), Polyethylene terephthalate glycol (PETG) and many more are available for 3D printing. Due to the wide range of applications in PLA, it is necessary to improve its toughness to make it more suitable by adding Poly Cyclohexylenedimethylene Terephthalate glycol (PCTG) …

Perspective On Predictive Modeling: Current Status, New High-Order Methodology And Outlook For Energy Systems, Dan Gabriel Cacuci

Faculty Publications

This work presents a perspective on deterministic predictive modeling methodologies, which aim at extracting best-estimate values for model responses and parameters along with reduced predicted uncertainties for these best-estimate values. The two oldest such methodologies are the data-adjustment method, which stems from the nuclear energy field, and the data-assimilation method, which is implemented in the geophysical sciences. Both of these methodologies attempt to minimize, in the least-square sense, a user-defined functional that represents the discrepancies between computed and measured model responses. These two methodologies were briefly reviewed and shown to be inconsistent even to first-order in the sensitivities of the …

Aerosol Synthesis Of Tungsten Bronze Particles For Nir Shielding, Hao Tu

Theses and Dissertations

This dissertation emphasizes the need for efficient energy use in buildings and transportation due to global warming and the energy crisis. It suggests that improving energy efficiency can help reduce energy consumption and emissions and support sustainability. The dissertation introduces various transparent materials that can block near-infrared (NIR) radiation from solar radiation to save energy and money, and it highlights the growing market value of such products. The dissertation compares tungsten bronze with other NIR shielding materials and shows its advantages. The dissertation introduces a cheap and environmentally friendly method for continuously producing tungsten bronze particles via aerosol synthesis. Particle …

Distillery, Clare Nicholas, Patrick Hanlon

Williams Honors College, Honors Research Projects

The goal for this project is to make a cost effective still. We will be implementing cost saving parts to create a cheap but effective still. From initial research conducted, we will try to combine a stainless steel still and copper still together so that the cheaper material (stainless steel) and the component that removes sulfur compounds (copper) are both implemented. The ME side of the project will focus on the actual design and construction of the parts that will be implemented into the still. Included in the design process will be calculations of heat transfer for the current and …

An Experimentally Validated Computational Model For The Degradation And Fracture Of Magnesium-Based Implants In A Chemically Corrosive Environment, Mark M. Ousdigian

Dissertations, Master's Theses and Master's Reports

In the orthopedic and cardiovascular fields there is a growing interest for biodegradable implants, which can be naturally degraded in the body environment over time so that no extraction surgery is required. These implants must be designed to maintain their strength until the fracture has healed in the body, which could be influenced by many factors such as -the patient’s age, activities, body weight, pre-existing conditions etc. Hence, an ideal implant design should be done on a patient-by-patient basis. In the present work, a computational model is developed to predict the degradation and fracture of magnesium-based implants in a stress-coupled …

Oxidation Layer Formation On Aluminum Substrates With Surface Defects Using Molecular Dynamics Simulation, Emmanuel Olugbade, Hiep Pham, Yuchu He, Haicheng Zhou, Chulsoon Hwang, Jonghyun Park

Electrical and Computer Engineering Faculty Research & Creative Works

Aluminum Oxide Layer Affects the Integrity of Electrical Contact and Can Contribute Adversely to Passive Intermodulation (PIM) Behavior in Radio Frequency (RF) Devices, necessitating a Need for Understanding its Formation Mechanism and Realistic Estimation of its Thickness. using ReaxFF Molecular Dynamics Simulation Technique, This Study Investigated the Impact of Surface Defects on Aluminum Oxide Layer Formation. Results Reveal that Crystallographic Orientation Did Not Affect the Kinetics of Oxidation Process of Aluminum. However, the Reaction Kinetics Increased Significantly with Surface Inhomogeneities Such as Cracks, Scratches, and Grain Boundaries. a Non-Uniform Oxide Layer with Thickness Variation in the Range of 72-77% Was …

Area Average Surface Transfer Coefficient In Unit Cell Geometries, Benjamin Gabriel Mackey

Masters Theses

"Honeycombs, metal foams, and lattice structures all provide a way to increase heat transfer due to better fluid mixing and larger surface area. Specifically, lattice structures can be a great way to provide heat transfer enhancement due to the ability to customize and optimize the unit cell geometry. In this research, a novel yet simple unit cell geometry is chosen for study. Four different configurations are tested in a lower Reynolds number range, 300–1800: single unit cell, two-unit cells in series, three-unit cells in series, and a 3x3 unit cell array. The Sherwood number of each configuration is found by …

Characterization And Improvement Of Powder Properties Through Plasma Spheroidization For Use In The Laser Powder Bed Fusion Process, M. Hossein Sehhat

Doctoral Dissertations

"This research was conducted to characterize the powder properties using different characterization techniques to enhance the powder behavior in the Laser Powder Bed Fusion (LPBF) process. One of the shortcomings of LPBF process is the high cost of gas-atomized powder feedstock. To overcome this downside, the cheaper water-atomized powder was characterized and used in LPBF process, and its performance was compared with those of gas-atomized powder. Also, the plasma spheroidization process was used to improve the powder characteristics; if the spheroidized powder could function as well as the virgin powder, plasma spheroidization process could be applied to the used powders …

Additively Manufactured Carbon Fiber- Reinforced Thermoplastic Composite Mold Plates For Injection Molding Process, C. Bivens, A. Wood, D. Ruble, M. Rangapuram, S. K. Dasari, K. Chandrashekhara, J. Degrange

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Polymer injection molding processes have been used to create high-volume parts quickly and efficiently. Injection molding uses mold plates that are traditionally made of very hard tool steels, such as P20 steel, which is extremely heavy and has very long lead times to build new molds. In this study, composite-based additive manufacturing (CBAM) was used to create mold plates using long-fiber carbon fiber and polyether ether ketone (PEEK). These mold plates were installed in an injection molding machine, and rectangular flat plates were produced using Lustran 348 acrylonitrile butadiene styrene (ABS). Tensile and flexural testing was performed on these parts …

Fine-Grained Activity Classification In Assembly Based On Multi-Visual Modalities, Haodong Chen, Niloofar Zendehdel, Ming-Chuan Leu, Zhaozheng Yin

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Assembly activity recognition and prediction help to improve productivity, quality control, and safety measures in smart factories. This study aims to sense, recognize, and predict a worker's continuous fine-grained assembly activities in a manufacturing platform. We propose a two-stage network for workers' fine-grained activity classification by leveraging scene-level and temporal-level activity features. The first stage is a feature awareness block that extracts scene-level features from multi-visual modalities, including red, green blue (RGB) and hand skeleton frames. We use the transfer learning method in the first stage and compare three different pre-trained feature extraction models. Then, we transmit the feature information …

Static I-V Based Pim Evaluation For Spring And Fabric-Over-Foam Contacts, Kalkidan W. Anjajo, Yang Xu, Shengxuan Xia, Yuchu He, Haicheng Zhou, Hanfeng Wang, Jonghyun Park, Chulsoon Hwang

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Spring Clips and Fabric-Over-Foams (FOFs) Are Widely Used in Mobile Devices for Electrical Connection Purposes. However, the Imperfect Metallic Connections Tend to Induce Passive Intermodulation (PIM), Resulting in a Receiver Sensitivity Degradation, Known as RP Desensitization. Due to the Complexity of the PIM Characterization, there is Not Yet a Way to Evaluate PIM Performance using a Simple Setup for Environments Like Factories. in This Paper, a Current-Voltage (I-V) Behavior-Based PIM Evaluation Method is Proposed and Validated with Various Metallic Contacts and Contact Forces. the Test Results Demonstrated the Feasibility of the PIM Performance Evaluation based on the Measured Static I-V …

Reinforcement Learning-Guided Quadratically Constrained Quadratic Programming For Enhanced Convergence And Optimality, Chaoying Pei, Zhi Xu, Sixiong You, Jeffrey Sun, Ran Dai

Mechanical and Aerospace Engineering Faculty Research & Creative Works

In the context of Quadratically Constrained Quadratic Programming (QCQP) with dynamic parameters, the effectiveness of various optimization approaches is heavily influenced by the quality of the initial guess. To address this challenge, this paper proposes a novel approach that leverages reinforcement learning (RL) to generate high-performing initial guesses for iterative algorithms, with the dynamic parameters serving as inputs. Our approach aims to accelerate convergence and improve the objective value, thereby enabling efficient and effective solutions to the QCQP problem under variability. In this study, we evaluate the proposed approach by applying it to an iterative algorithm, specifically the Iterative Rank …

Mixed-Input Learning For Multi-Point Landing Guidance With Hazard Avoidance Part Ii: Learning-Based Guidance Algorithm, Sixiong You, Chaoying Pei, Vinay Kenny, Ran Dai, Jeremy R. Rea

Mechanical and Aerospace Engineering Faculty Research & Creative Works

This paper investigates the three-dimensional (3D) multi-point landing guidance (MLG) problem with hazard avoidance by developing a mixed-input learning-based method to achieve precise and fuel-efficient planetary landing in future Mars missions. Specifically, we aim to find a safe, fuel-efficient landing point and generate a fuel-optimal trajectory simultaneously in real-time. First, by introducing binary variables, the MLG problem is formulated as an optimal control problem with quadratic constraints. Then, by formulating the Hamiltonian function, the necessary conditions of optimality for the MLG problem are obtained, where the critical parameters are identified to represent the complete optimal solution. After that, to find …

Feature-Based Learning For Optimal Abort Guidance, Vinay Kenny, Sixiong You, Godfrey Hendrix, Chaoying Pei, Roha Gul, Ran Dai, Jeremy R. Rea

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The abort mission refers to the mission where the landing vehicle needs to terminate the landing mission when an anomaly happens and be safely guided to the desired orbit. This paper focuses on solving the time-optimal abort guidance (TOAG) problem in real-time via the feature-based learning method. First, according to the optimal control theory, the features are identified to represent the optimal solutions of TOAG using a few parameters. After that, a sufficiently large dataset of time-optimal abort trajectories is generated offline by solving the TOAG problems with different initial conditions. Then the features are extracted for all generated cases. …

Distributed Optimization For Rank-Constrained Semidefinite Programs, Chaoying Pei, Sixiong You, Chuangchuang Sun, Ran Dai

Mechanical and Aerospace Engineering Faculty Research & Creative Works

This letter develops a distributed optimization framework for solving the rank-constrained semidefinite programs (RCSPs). Since the rank constraint is non-convex and discontinuous, solving an optimization problem with rank constraints is NP-hard and notoriously time-consuming, especially for large-scale RCSPs. In the proposed approach, by decomposing an unknown matrix into a set of submatrices with much smaller sizes, the rank constraint on the original matrix is equivalently transformed into a set of constraints on the decomposed submatrices. The distributed framework allows parallel computation of subproblems while requiring coordination among them to satisfy the coupled constraints. As the scale of every subproblem solved …

Orbital Stabilization Of Underactuated Systems Using Time Period Regulation, Nilay Kant, Ranjan Mukherjee

Mechanical and Aerospace Engineering Faculty Research & Creative Works

A new approach to orbital stabilization of under-actuated systems with one passive degree-of-freedom (DOF) is presented. Virtual holonomic constraints are enforced using partial feedback linearization; this results in a dense set of periodic orbits on a constraint manifold. Every orbit on the constraint manifold is associated with a unique time-period. A desired orbit is selected, and the impulse controlled Poincaré map (ICPM) approach is utilized to stabilize the orbit by regulating the time-period. By treating the time period as the output, it is possible to design a dead-beat controller that achieves orbital stabilization in a single time-step. The effectiveness of …

Design And Development Of Smart Wardrobe Technology, Mikhail Filatov

All Graduate Theses, Dissertations, and Other Capstone Projects

The increasing demand for online shopping in the 21st century is causing rapid growth in technology and methods in marketing and sales fields. Present thesis work scrutinizes the process of design and development of the device that simplifies the process of trying on and buying clothes in online retail stores, the development of which is based on the known basics of operational, mechanical, and electrical designs for computational systems, with account for ergonomics and manufacturing sustainability. The following research represents the market analysis for competition identification, description of all operational modes of the system, list of mechanical and electrical components …

A Coupled Source Panel, Actuator Line, And Viscous Vortex Particle Method In An O(N) Scheme, Ryan Anderson, Andrew Ning

Faculty Publications

Wake interactions play a significant role in aerodynamics. However, common modeling approaches are either expensive or lack fidelity, making them unreliable or difficult to use in the design process. The vortex particle method can capture the relevant physics effectively, but imposing boundary conditions with solid surfaces in a computationally efficient way is challenging. We explore two possible methods of imposing solid surface boundary conditions of vortex particle simulations. The first, a novel variation on a pure particle approach, is easy to implement but is moderately expensive, and suffers from some numerical instability. The second, source panels accelerated with a fast …

Comparison Of The Thermal Stability In Equal-Channel-Angular-Pressed And High-Pressure-Torsion-Processed Fe–21cr–5al Alloy, Maalavan Arivu, Andrew Hoffman, Jiaqi Duan, Jonathan Poplawsky, Xinchang Zhang, Frank W. Liou, Rinat Islamgaliev, Ruslan Valiev, Haiming Wen

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Nanostructured Steels Are Expected to Have Enhanced Irradiation Tolerance and Improved Strength. However, They Suffer from Poor Microstructural Stability at Elevated Temperatures. in This Study, Fe–21Cr–5Al–0.026C (Wt%) Kanthal D (KD) Alloy Belonging to a Class of (FeCrAl) Alloys Considered for Accident-Tolerant Fuel Cladding in Light-Water Reactors is Nanostructured using Two Severe Plastic Deformation Techniques of Equal-Channel Angular Pressing (ECAP) and High-Pressure Torsion (HPT), and their Thermal Stability between 500–700 °C is Studied and Compared. ECAP KD is Found to Be Thermally Stable Up to 500 °C, Whereas HPT KD is Unstable at 500 °C. Microstructural Characterization Reveals that ECAP KD …

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

Mechanical and Aerospace Engineering Faculty Research & Creative Works

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

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

Mechanical and Aerospace Engineering Faculty Research & Creative Works

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