Mechanical Engineering Commons^™

Dry Reforming Of Methane Using Microwave Irradiated Metal Oxide/Coal Char Catalysts, Anthony Carter

Graduate Theses, Dissertations, and Problem Reports (ETD)

This research focuses on the synthesis of both shaped and amorphous powder materials, the combination of these materials with dried Powder River Basin (PRB) coal char, and their reactionary properties with methane and carbon dioxide gasses with conventional and microwave (MW) heating. The first goal of this project was to synthesize shaped micro and nano sized particles with ideal dielectric properties for converting electromagnetic energy into heat and proven capabilities of activating methane. These particles were synthesized via solvothermal, hydrothermal, and co-preceptory treatments alone and onto the surface of dried PRB coal char. PRB is a sub-bituminous, low-ranking coal (LRC) …

Computational Intelligent Impact Force Modeling And Monitoring In Hislo Conditions For Maximizing Surface Mining Efficiency, Safety, And Health, Danish Ali

Doctoral Dissertations

"Shovel-truck systems are the most widely employed excavation and material handling systems for surface mining operations. During this process, a high-impact shovel loading operation (HISLO) produces large forces that cause extreme whole body vibrations (WBV) that can severely affect the safety and health of haul truck operators. Previously developed solutions have failed to produce satisfactory results as the vibrations at the truck operator seat still exceed the “Extremely Uncomfortable Limits”. This study was a novel effort in developing deep learning-based solution to the HISLO problem.

This research study developed a rigorous mathematical model and a 3D virtual simulation model to …

Fabrication, Characterization Of High-Entropy Alloys And Deep Learning-Based Inspection In Metal Additive Manufacturing, Wenyuan Cui

Doctoral Dissertations

"Alloying has been used to confer desirable properties to materials. It typically involves the addition of small amounts of secondary elements to a primary element. In the past decade, however, a new alloying strategy that involves the combination of multiple principal elements in high concentrations to create new materials called high- entropy alloys (HEAs) has been in vogue. In the first part, the investigation focused on the fabrication process and property assessment of the additive manufactured HEA to broaden its engineering applications. Additive manufacturing (AM) is based on manufacturing philosophy through the layer-by-layer method and accomplish the near net-shaped components …

Thermomechanical Simulation And Process Optimization For Hot Rolling Of Steel, Shouvik Ganguly

Doctoral Dissertations

"Hot rolling is a manufacturing process that involves large material deformation, complicated geometries, contact conditions and non-uniform temperature gradients. Steel industries are motivated to prevent hot rolled steel products to be defect free and with desired shape and size. In order to simulate the process accurately, it is essential that the material model for steel accounts for the viscoplasticity and changes in properties that occur in steel at elevated temperatures as grain growth and recrystallization.

The healing of existing voids during hot rolling was investigated using finite element simulations. Voids are highly undesirable as they not only degrade the product …

Fabrication Of 304l Stainless Steel And Aluminum Parts By Laser Foil Printing And Process Automation, Chia-Hung Hung

Doctoral Dissertations

"This work presents research conducted on a novel metal additive manufacturing process, called Laser Foil Printing (LFP), to fabricate metal parts with various geometries layer by layer using metal foil as the feedstock. To investigate the processability and characteristics of LFP for fabricating metal parts, the materials included 304L stainless steel and Al-1100 aluminum alloy. The LFP process parameter windows for both 304L and Al-1100 were determined, and the optimal process parameters with stable formation of the melt pools were selected to fabricate dense metal parts. The microstructure and properties of LFP-fabricated parts were characterized and analyzed using tensile testing, …

Numerical And Experimental Study Of Mechanical Properties For Laser Metal Deposition (Lmd) Process Part, Lan Li

Doctoral Dissertations

"Laser Metal Deposition (LMD), also called as, Laser Engineered Net Shaping (LENS), Directed Energy Deposition (DED), is a typical Additive Manufacturing (AM) technology, is used for advanced free-form fabrication. It creates parts by directly melting materials and depositing them on the workpiece layer by layer. In this process, the metal powder or fiber is melted within the melting pool by laser beam or electron beam and quickly solidifies to the deposited layer. LMD technology shows great advantages over traditional manufacturing on complex structure fabrication, including high building rates, easy material replacement and reduced material waste. These merits make the wide …

Dynamic Behavior And Interactions Of Ferrofluid Droplets Under Magnetic Fields In Low Reynolds Number Flows, Md Rifat Hassan

Doctoral Dissertations

Digital microfluidics in combination with emulsion microfluidics are crucial building blocks of droplet-based microfluidics, which are prevalent in a wide variety of industrial and biomedical applications, including polymer processing, food production, drug delivery, inkjet printing, and cell-based assays. Therefore, understanding the dynamics and interactions of droplets as well as the interactions between the droplets and solid surfaces are of great importance in order to improve the performance or product in these applications.

Recently, several studies in the literature have demonstrated the potential of magnetic fields in controlling the behavior of droplets in microscale; however, the fundamental mechanism behind the interesting …

An Investigation Of Unsteady Thermal Exchange Processes In Geothermal Heat Exchangers, Ganesh Ravi Shanker

Doctoral Dissertations

“Geothermal heat exchangers, has become one of the highly recognized non conventional heat exchangers as they utilize renewable energy source earth to initiate the thermal energy transfer. However, these heat exchangers suffer from a expensive installation cost due to their conservative design model, thereby facilitating the need to identify and improve the design. In this dissertation, three gaps, which identifies improvement over conservative design were investigated, to assess the heat exchanger performance. In the first approach, borehole thermal and geometrical properties were investigated keeping the outlet leg of the heat exchanger as adiabatic, which neglects the thermal short-circuiting between the …

Development Of In-Situ Radiometric Inspection Methods For Quality Assurance In Laser Powder Bed Fusion, Cody S. Lough

Doctoral Dissertations

“Laser Powder Bed Fusion (LPBF) metal Additive Manufacturing (AM) fabricates 3D metal parts layer-by-layer. The process enables production of geometrically complex parts that are difficult to inspect with traditional methods. The LPBF parts experience significant geometry driven thermal variations during manufacturing. This creates microstructure and mechanical property inhomogeneities and can stochastically cause defects. Mission critical applications require part qualification by measuring the defects non-destructively. The layer-to-layer nature of LPBF permits non-intrusive measurement of radiometric signals for a part’s entire volume. These measurements provide thermal features that correlate with the local part health. This research establishes Optical Emission Spectroscopy (OES) and …

Additively Manufactured Metallic Cellular Structures, Okanmisope Aziel Fashanu

Doctoral Dissertations

"Cellular structures are lightweight structures with excellent mechanical, thermal, and acoustic properties. They offer promise in a series of applications, including lightweight applications, sandwich cores, mechanical damping, acoustic absorption, strain isolation, and thermal management. The manufacturing of these complex cellular structures is expensive and time-consuming, which hinders the adoption of these structures in many industries. Advancement in manufacturing technologies, such as additive manufacturing (AM), however, have changed this. AM allows for the rapid and less expensive manufacturing of complex cellular structures. This work aimed to investigate the performance of additively manufactured cellular structures for lightweight and sandwich core applications. In …

Advanced Battery Modeling For Interfacial Phenomena And Optimal Charging, Yaqi Zhu

Doctoral Dissertations

"Lithium-ion batteries are one of the most promising energy storage systems for portable devices, transportation, and renewable grids. To meet the increasing requirements of these applications, higher energy density and areal capacity, long cycle life, fast charging rate and enhanced safety for lithium-ion battery (LIBs) are urgently needed. To solve these challenges, the relevant physics at different length scale need to be understood. However, experimental study is time consuming and limited in small scale’s study. Modeling techniques provide us powerful tools to get a deep understanding of the relevant physics and find optimal solutions. This work focuses on studying the …

Prediction Of Battery Health Dynamics, Damola Martins Ajiboye

Doctoral Dissertations

"The successful market penetration of lithium-ion batteries in the last 30 years has ushered in a new dawn in energy applications. Notwithstanding their widespread use, lithium-ion batteries are affected by a plethora of fundamental issues — safety, cycle life, performance, and cost. In this work, advanced modeling techniques are developed to tackle some of these issues. This dissertation is subdivided into four parts, the first is introduction while the remaining are dedicated to the development of computational techniques for predicting battery health dynamics.

In the second part of this work, we developed fast and accurate algorithms for modeling essential battery …

Sources Of Quality Uncertainty In Laser Powder Bed Fusion Metal Additive Manufacturing, Zachary Young

Doctoral Dissertations

"Powder based additive manufacturing (AM) exhibits tremendous uncertainties, where variations in build quality is present despite utilizing similar build processing parameters. First, this work reports the features and formation mechanisms of five unique types of spatter during the LPBF process by in-situ high-speed, high-energy x-ray imaging. The unique physical characteristics of spatter are determined. The effect of laser scan speed and laser power on spatter formation, ejection, and mitigation are determined. Second, this work addresses the uncertainty challenge by identifying the sources of uncertainty in SLM by in-situ characterization due to variations from the additive manufacturing processing parameters needed for …

Development And Characterization Of Nb₃N/Al₂0₃ Superconducting Multilayers For Particle Accelerators, Chris Sundahl, Junki Makita, Paul B. Welander, Yi-Feng Su, Fumitake Kametani, Lin Xie, Huimin Zhang, Lian Li, Alex Gurevich, Chang-Beom Eom

Physics Faculty Publications

Superconducting radio-frequency (SRF) resonator cavities provide extremely high quality factors > 10¹⁰ at 1-2 GHz and 2 K in large linear accelerators of high-energy particles. The maximum accelerating field of SRF cavities is limited by penetration of vortices into the superconductor. Present state-of-the-art Nb cavities can withstand up to 50 MV/m accelerating gradients and magnetic fields of 200-240 mT which destroy the low-dissipative Meissner state. Achieving higher accelerating gradients requires superconductors with higher thermodynamic critical fields, of which Nb₃Sn has emerged as a leading material for the next generation accelerators. To overcome the problem of low vortex penetration …

One-Dimensional Lateral Force Anisotropy At The Atomic Scale In Sliding Single Molecules On A Surface, Yuan Zhang, Daniel J. Trainer, Badri Narayanan, Yang Li, Anh T. Ngo, Sushila Khadka, Arnab Neogi, Brandon Fisher, Larry A. Curtiss, Subramanian K.R.S. Sankaranarayanan, Saw Wai Hla

Physics Faculty Publications

Using a q+ atomic force microscopy at low temperature, a sexiphenyl molecule is slid across an atomically flat Ag(111) surface along the direction parallel to its molecular axis and sideways to the axis. Despite identical contact area and underlying surface geometry, the lateral force required to move the molecule in the direction parallel to its molecular axis is found to be about half of that required to move it sideways. The origin of the lateral force anisotropy observed here is traced to the one-dimensional shape of the molecule, which is further confirmed by molecular dynamics simulations. We also demonstrate that …

Effect Of Hearing And Head Protection On The Localization Of Tonal And Broadband Reverse Alarms, Chantal Laroche, Christian Giguère, Véronique Vaillancourt, Claudia Marleau, Marie-France Cadieux, Karina Laprise-Girard, Emily Gula, Véronique Carroll, Manuelle Bibeau, Hugues Nélisse

Études primaires

Objective

This study explored the effects of hearing protection devices (HPDs) and head protection on the ability of normal-hearing individuals to localize reverse alarms in background noise.

Background

Among factors potentially contributing to accidents involving heavy vehicles, reverse alarms can be difficult to localize in space, leading to errors in identifying the source of danger. Previous studies have shown that traditional tonal alarms are more difficult to localize than broadband alarms. In addition, HPDs and safety helmets may further impair localization.

Method

Standing in the middle of an array of eight loudspeakers, participants with and without HPDs (passive and level-dependent) …

Investigating Nox Vs Co2 Tradeoff In Heavy Duty Emissions Through The Years Under The Scope Of Carb’S 3-Bin Moving Average Window Method, Ghadi Sadek

Graduate Theses, Dissertations, and Problem Reports (ETD)

With the rise in urban pollution level over the last few years, regulatory agencies around the world have taken multiple steps to ensure engine exhaust pollutant are well monitored and properly regulated. Yet there exists a significant difference in emissions rates in various operating conditions between US and European products which currently uses a Moving average window (MAW) approach for their in-use compliance testing and certification program. Using WVU’s vehicle data collected using PEMS devices, this study aims at investigating the NOx versus CO2 tradeoff found in heavy duty diesel engines equipped with different aftertreatment technologies, under the scope of …

An Equest Based Building Energy Modeling Analysis For Energy Efficiency Of Buildings, Saroj Lamichhane

Graduate Theses, Dissertations, and Problem Reports (ETD)

Building energy performance is a function of numerous building parameters. In this study, sensitivity analysis on twenty parameters is performed to determine the top three parameters which have the most significant impact on the energy performance of buildings. Actual data from two fully operational commercial buildings were collected and used to develop a building energy model in eQUEST. The model is calibrated using Normalized Mean Bias Error (NMBE) and Coefficient of Variation of Root Mean Square Error (CV(RMSE)) method. The model satisfies the NMBE and CV(RMSE) criteria set by the American Society of Heating, Refrigeration, and Air-Conditioning (ASHRAE) Guideline 14, …

Experimental And Numerical Investigation Of Naca Airfoil Wing With Winglets, Courtney Danielle Bachmann

College of Graduate Studies: Theses & Dissertations

This research was performed in order to study wingtip devices and, in particular, winglets. Winglets are attached to commercial aircraft for the purpose of reducing induced drag caused by wake vortices on the wingtip. A winglet device can save an aircraft anywhere from 3-7% in fuel consumption. Over the course of a year, this can add up to hundreds of thousands of dollars saved. This research consisted of two parts: one part experiment and one part equipment design. The latter phase of this research examined various methods of testing in a subsonic wind tunnel laboratory setting. Experimental results found with …

Synthetic Approach Of Ternary Magnesium Niobate (Mg–Nb–O) Compounds, Md. Wasikur Rahman

Mechanical Engineering Faculty Publications

Magnesium based niobium oxides (Mg–Nb–O) were prepared by solid-state reactions owing to understand the function of transition metal oxides as promoters/catalysts for practical application. Magnesium niobate (Mg3Nb6O11) was synthesized for the first time in nearly pure form reported in this context. MgNb2O6 and Mg4Nb2O9 were prepared in oxidizing conditions; on the contrary, Mg3Nb6O11 preferred reducing environment. Stoichiometric mixtures of the precursor materials MgO, Nb2O5 and/or metallic Nb were annealed for the syntheses which revealed the effect of temperature on phase formation, reaction kinetics and heat of reaction. The products were examined by ex-situ, in-situ X-ray diffraction (XRD) and differential scanning …

Recent Progress Trend On Abrasive Waterjet Cutting Of Metallic Materials: A Review, Jennifer Milaor Llanto, Majid Tolouei-Rad, Ana Vafadar, Muhammad Aamir

Research outputs 2014 to 2021

Abrasive water jet machining has been extensively used for cutting various materials. In particular, it has been applied for difficult-to-cut materials, mostly metals, which are used in various manufacturing processes in the fabrication industry. Due to its vast applications, in-depth comprehension of the systems behind its cutting process is required to determine its effective usage. This paper presents a review of the progress in the recent trends regarding abrasive waterjet cutting application to extend the understanding of the significance of cutting process parameters. This review aims to append a substantial understanding of the recent improvement of abrasive waterjet machine process …

Safety Analysis Of Battery-Powered Adaptive Ride-On Toys For Children With Disabilities, Abbey Fraser

UNF Graduate Theses and Dissertations

Modified battery-powered ride-on toy cars, or adaptive ride-on toys, represent novel rehabilitation tools and developmental aids for children with disabilities. Studies have shown that children are benefiting socially and developmentally from their use. However, the use of these toys by children with disabilities potentially poses a risk of injury and it is vitally important to ensure the safe use of these toys, particularly for the benefit of those with developmental challenges.

Within this context, the purpose of the first study was to determine whether modifications to ride-on toys are sufficient to prevent common modes of injury such as falls, passenger …

Macrotexture Assessment Of Florida Pavements, Alexander C. Oracheff

UNF Graduate Theses and Dissertations

When water has nowhere to escape from the surface of a roadway, it can disrupt the tire-to-pavement adhesion of a traveling vehicle and lead to hydroplaning. Pavement macrotexture provides the pathways for water to drain, which allows for the necessary grip between tire and pavement. Macrotexture, which is quantified by the Florida Department of Transportation (FDOT) in terms of mean profile depth (MPD), is analyzed by the State Materials Office using a high-speed point-laser mounted along the driver side wheel path of a friction testing vehicle.

While point-lasers are capable of accurately measuring MPD on flexible pavement, the system fails …

Advance Metallic Reinforcement Of Vat Photo Polymerized Parts, Scott Zinn

UNF Graduate Theses and Dissertations

The metallization or metallic reinforcement of polymer parts has been widely used in industry for several decades. Polymer parts are classically metalized for aesthetics, chemical and thermal resistance, electrical conductivity, and mechanical strength. Metallization has been shown to increase strength of polymer parts when compared to the strength of the bulk material without metallization. Additive manufacturing (AM) techniques that have emerged in the last few decades produce parts with different surface features and chemistry than the typical polymer part produced through injection molding. AM parts are typically weaker than traditionally manufactured parts from the same material due to intrinsic details …

The Investigation Of The Underlying Microstructure Associated With Fracture Features In 6061 Cold Sprayed Aluminum, Justin White

UNF Graduate Theses and Dissertations

Cold gas dynamic spraying commonly known as cold spray is a process currently used for restoration, re-tolerancing, and application of coatings. With additional resources allocated towards the development of a through process model aimed at predicting the properties of bulk material produced via the Cold Spray process, more lab testing and investigation must be done to capture the effects of the varying microstructure in CS materials. The properties of ultra-fine-grained materials are derived from data collected from coarse grained materials and processes that do not accurately capture the effects as elevated strain rates and ultra-fine-grained materials. The lack of property …

An Accuracy And Precision Analysis Of The Velys™ Robotic Assisted Solution For Total Knee Arthroplasty, Gary Doan

Electronic Theses and Dissertations

Total knee arthroplasty (TKA) is a procedure where the arthritic surfaces of the knee is removed and replaced with a combination of metal and polymer implants that recreates the joint line to restore function and quality of life. Implant alignment is important in the success of a TKA. Modern day conventional instrumentation can be cumbersome in the operating room and can be inaccurate when resecting bone and aligning implants. Patients with large errors in resections and implant orientation are more prone to experience mechanical failures with their TKA. Mechanical failures in primary TKA require revision surgeries which can lead to …

Broadening The Capability Of Kinetics Analysis In Biomechanics, Nicholas Nelson

Electronic Theses and Dissertations

Two studies are discussed in this manuscript each preceded by a literature review of the topic. The first review and study explore agility movements and the effect that alternative upper designs in shoes might have on ground reaction force measures of performance. The second review and study evaluate methods of predicting ground reaction forces without the use of a force platform. A method of using effective forces and ways of improving its accuracy are evaluated in depth.

Novel Piezo Actuators For Surface Cleaning, Yezad H. Anklesaria

Doctoral Dissertations

"Optical cameras are becoming increasingly common and are used in a variety of applications. With recent progress and transition toward more autonomous systems, the usage of optical systems will be common and widespread. Applications of the optical systems range from autonomous vehicles, home security systems, aviation, extraterrestrial vehicles, spacecraft, and satellites. Imaging systems are used in decision-making in many of these applications. Fouling of the field of view of the imaging system can impede the decision process. An active autonomous cleaning method for the optical surface of the optical systems reliably would be advantageous. The research work focuses on developing …

Elastic Bending Behaviour Of Sandwich Composite Structures With Abs Cores By Using Additive Manufacturing, Dechawat Wannarong

Chulalongkorn University Theses and Dissertations (Chula ETD)

Maintaining the lightweight performance of sandwich structures while achieving good bending strength and stiffness is difficult. Core materials for these programmable sandwich constructions are 3D printed with hexagonal honeycomb, re-entrant honeycomb, and circular honeycomb topologies with varying core densities. The bending stiffness and strength of these sandwich structures are determined by a three points bending test including an Acrylonitrile Butadiene Styrene core and a unidirectional carbon fibre reinforced polymer face sheet. The sandwich composite with the greater relative core density displays greater bending strength and stiffness than the composite with the lower relative core density. The sandwich composites beam with …

Effectiveness Of The New Ambulance Air Exhaust System In Reducing Aerosol Particle Concentration, Vasutorn Petrangsan

Chulalongkorn University Theses and Dissertations (Chula ETD)

The objective of this work is to assess the effectiveness in reducing airborne particles of the Camfil® CC410-concealed air exhaust system, that is installed in the ER-1 ambulance (a King Chulalongkorn Memorial Hospital ambulance). This is done by diffusing aerosols into the cabin at the patient’s face position for an injection period (IP) of 1 minute and measuring the aerosol concentration inside the cabin over time. The experiment is conducted for 2 ventilation conditions, when the exhaust system is off (Minimal Ventilation: MV) and at maximum speed (High Ventilation: HV). Density of the aerosol is interpreted in terms of its …