Engineering Commons^™

Expanding Faculty-Student Interactions In Statics: An Exploratory Study Of A Statics Course With Learning Assistants, Valerie V. Bracho Perez

FIU Electronic Theses and Dissertations

Statics is one of the first fundamental engineering classes within the ME undergraduate curriculum, in which a student’s performance in the course can impact their overall academic success. Recent efforts to enhance students learning in fundamental engineering courses have included integrating Learning Assistants (LAs), undergraduate peers who have previously excelled in the course, into the instructional team of the course. The purpose of this Master's thesis is to explore the enactment of a Statics classroom with LAs, the interactions that characterize it, and the impact it has on the students and instructional teams. A qualitative case study of a Statics …

Development Of A Miniature Pipe Crawler For Application In Fossil Energy Power Plants, Caique C. Lara

FIU Electronic Theses and Dissertations

The power generation of fossil fuel power plants relies on burning coal to generate steam. The heat exchange between the water and burned coal occurs in the combustion chamber, which operates at a high pressure and temperature. Monitoring the integrity of the tubes inside the combustion chamber is a key factor to avoid failures. However, this is not an easy task as some areas are hard to reach and the pipeline commonly has a complex geometry. Moreover, the inspection is typically manual, external and the environment is hazardous for humans. This thesis presents the development and testing of an electrically …

Numerical Modeling And Conjugate Heat Transfer Analysis Of Single U-Tube Vertical Borehole Heat Exchangers, Talha Khan

FIU Electronic Theses and Dissertations

The primary purpose of this thesis was to develop a design for improving the efficiency of the vertical type single u-tube borehole heat exchanger. A thorough literature review of the various existing analytical and numerical models of the borehole heat exchanger (BHEs) was performed and numerical modeling of the BHE was conducted to solve the conjugate heat transfer problem in the BHE in 3D using ANSYS Fluent 2019 R1. A comparison between the results obtained using various mesh sizes, types, different turbulence models showed the independence of the parameters on the numerical simulation results.

From the numerical simulation, it was …

Structural Health Monitoring Of Pipelines In Radioactive Environments Through Acoustic Sensing And Machine Learning, Michael Thompson

FIU Electronic Theses and Dissertations

Structural health monitoring (SHM) comprises multiple methodologies for the detection and characterization of stress, damage, and aberrations in engineering structures and equipment. Although, standard commercial engineering operations may freely adopt new technology into everyday operations, the nuclear industry is slowed down by tight governmental regulations and extremely harsh environments. This work aims to investigate and evaluate different sensor systems for real-time structural health monitoring of piping systems and develop a novel machine learning model to detect anomalies from the sensor data. The novelty of the current work lies in the development of an LSTM-autoencoder neural network to automate anomaly detection …

A Comprehensive Analysis Of Balance, Symmetry, And Center Of Mass In The Gait Cycle Of Transfemoral Amputees, Kayla T. Etienne

FIU Electronic Theses and Dissertations

The purpose of this thesis is to create a framework that assists in the transfemoral prosthesis fitting process by calculating balance and symmetry to quantify patient comfort with an understanding of bipedal locomotion and human anatomy. Three different software applications were used to compare (1) the body position during gait cycle, (2) the natural and amputee anatomies, (3) the natural and prosthetic legs, and (4) the equilibrium and torque movements of the hip, knee, and ankle joints. Models were created in Maya for analysis in Solidworks and MEL code evaluation with MatLab. The MatLab code tested combinations of joint degrees …

Boron Nitride Nanotube Based Lightweight Metal Matrix Composites: Microstructure Engineering And Stress-Transfer Mechanics, Pranjal Nautiyal

FIU Electronic Theses and Dissertations

Lightweight metals, such as Aluminum, Magnesium and Titanium, are receiving widespread attention for manufacturing agile structures. However, the mechanical strength of these metals and their alloys fall short of structural steels, curtailing their applicability in engineering applications where superior load-bearing ability is required. There is a need to effectively augment the deformation- and failure-resistance of these metals without compromising their density advantage.

This dissertation explores the mechanical reinforcement of the aforementioned lightweight metal matrices by utilizing Boron Nitride Nanotube (BNNT), a 1D nanomaterial with extraordinary mechanical properties. The nanotubes are found to resist thermo-oxidative transformations up to ~750°C, establishing their …

Parametric Studies Of Reciprocating-Flow Heat Transfer In A Reciprocating Loop Device, Majid Abdulmajeed Almas

FIU Electronic Theses and Dissertations

It is anticipated that clean vehicles such as Electric Vehicles (EVs) may dominate ground transportation in the future. Reliable and lower-cost batteries are essential to the growth of EV industries. A literature review reveals that if non-uniformity of battery operating temperature reaches about 9.0 ^oC, the capacity of the battery pack could drop by more than 30%, Also, If the operating temperature of the battery system exceeds 40 ^oC or is below 0 ^oC, the battery power could decrease dramatically and eventually to zero. However, excellent battery thermal-management systems that improve battery capacity and operational life have …

Composite Gel Polymer Electrolytes For Extended Cyclability Of Lithium-Oxygen Batteries, Marcus Carlton Herndon

FIU Electronic Theses and Dissertations

In lithium-oxygen (Li-O₂) batteries, addressing challenges like electrode degradation, cell stability and electrolyte decomposition are key to creating more practical applications. Despite many attempts to minimize anode oxidation and cathode byproduct formation, the electrolyte remains the leading source for rapid capacity fading and poor cyclability in Li-O₂batteries. Understanding the loss of functionality in electrolytes, carbon nanotube (CNT) fillers and redox mediators (RM), during cycling within Li-O₂battery systems, could be the solution to prolonging battery lifetime. Determining the efficiency of these battery components and additives will push the medium towards lifelong, rechargeable and safe battery …

Mechanical Properties Of Permanent Foaming Fixatives For Deactivation & Decommissioning Activities, Tristan Maximilian Simoes-Ponce

FIU Electronic Theses and Dissertations

The Department of Energy is investigating fixative technologies that encapsulate and/or immobilize residual contamination in voids during deactivation and decommissioning (D&D). These technologies must have adequate mechanical and adhesion properties to withstand seismic activity that may occur. One solution is the implementation of polyurethane foams used as permanent foaming fixatives (PFF), specifically intumescent foams that contain expandable graphite, making them fire resistant when exposed to extreme heat conditions.

Tensile, compression, seismic, and tensile adhesion testing was done on six commercial-off-the-self polyurethane foams to determine if the expandable graphite and other filler intumescent technologies improve its mechanical limits. It was found …

Constructal Design And Aeroelastic Stability Analysis Of Hale Aircraft, Ehsan Izadpanahi

FIU Electronic Theses and Dissertations

In the new generation of the Unmanned Aerial Vehicle (UAV), the capability of increasing the flight duration and altitude is the area of interest for designers. The High-Altitude Long-Endurance (HALE) aircraft can fly farther and for a longer period by using high aspect ratio flexible wings. The primary applications and flight missions of this type of aircraft are environmental monitoring, surveillance, and communications. While using high-aspect-ratio, flexible, light-weighted wings improve the efficiency and reduces the required power, it will bring new challenges into the design of the aircraft. One of the major concerns is aeroelastic instability, which can appear as …

The Applications Of Intumescent Technologies In Support Of D&D Activities Across The Doe Complex, Joshua Alan Nunez

FIU Electronic Theses and Dissertations

Nuclear facilities in the process of Deactivation and Decommissioning (D&D) face several enormous challenges. Decommissioning is only part of the final shutdown process of a nuclear facility. The majority of the DOE facilities, like most industries, face fire hazards or extreme heat conditions. This study aims to research, test, and validate the operational performance of commercially available polyurethane expanding intumescent foams as potential fixatives for immobilizing residual contamination while preserving fire resiliency. Due to the novelty of this unique problem set and approach, existing international standards (ASTM/NIST/etc.) were reviewed for best-fit platforms with which to build testing protocols from. Once …

High-Power Biofuel Cells Based On Threedimensional Reduced Graphene Oxide/ Carbon Nanotube Micro-Arrays, Yin Song, Chunlei Wang

Department of Mechanical and Materials Engineering

Miniaturized enzymatic biofuel cells (EBFCs) with high cell performance are promising candidates for powering next-generation implantable medical devices. Here, we report a closed-loop theoretical and experimental study on a micro EBFC system based on three-dimensional (3D) carbon micropillar arrays coated with reduced graphene oxide (rGO), carbon nanotubes (CNTs), and a biocatalyst composite. The fabrication process of this system combines the top–down carbon microelectromechanical systems (C-MEMS) technique to fabricate the 3D micropillar array platform and bottom–up electrophoretic deposition (EPD) to deposit the reduced rGO/CNTs/enzyme onto the electrode surface. The Michaelis–Menten constant KM of 2.1 mM for glucose oxidase (GOx) on the …

Many-Objective Hybrid Optimization Under Uncertainty With Applications, Sohail Reddy

FIU Electronic Theses and Dissertations

A novel method for solving many-objective optimization problems under uncertainty was developed. It is well known that no single optimization algorithm performs best for all problems. Therefore, the developed method, a many-objective hybrid optimizer (MOHO), uses five constitutive algorithms and actively switches between them throughout the optimization process allowing for robust optimization. MOHO monitors the progress made by each of the five algorithms and allows the best performing algorithm more attempts at finding the optimum. This removes the need for user input for selecting algorithm as the best performing algorithm is automatically selected thereby increasing the probability of converging to …

Toward A Fast And Accurate Modeling Strategy For Thermal Management In Air-Cooled Data Centers, Long Tran Bao Phan

FIU Electronic Theses and Dissertations

Computational fluid dynamics (CFD) has become a popular tool compared to experimental measurement for thermal management in data centers. However, it is very time-consuming and resource-intensive when used to model large-scale data centers, and may not be ready for real-time thermal monitoring. In this thesis, the two main goals are first to develop rapid flow simulation to reduce the computing time while maintaining good accuracy, and second, to develop a whole building energy simulation (BES) strategy for data center modeling. To achieve this end, hybrid modeling and model training methodologies are investigated for rapid flow simulation, and a multi-zone model …

Dynamics Of Falling Droplet Under Effects Of Electric Fields, Esmaiil Ghasemisahebi

FIU Electronic Theses and Dissertations

Physical properties and especially the size of drops are important parameters in many industrial and medical applications. High voltage electric field is one of the effective means to control the final size of drops during the fabrication process which could greatly influence the final size of the product. Therefore a detailed study of electric field effect on a liquid drop is very important. In this work deformation and fragmentation of a falling droplet under gravity and electric force have been studied numerically. The electric force is used as an effective external controlling mechanism to influence the deformation of a drop. …

A Computational Approach For Modeling Plasma Sprayed Coatings From Splat To Bulk Deposits, Sadhana Bhusal

FIU Electronic Theses and Dissertations

In this study, a multi-pronged computational approach is developed to predict the effect of spray parameters on aluminum oxide splat formation and mechanical properties of the coatings. The splat morphology is investigated using computational fluid dynamics approach. Simulated splat morphologies show a good agreement with the experimentally obtained splats. Three-dimensional coating structure is constructed using the stochastic approach using simulated splat morphologies. Finite Element Analysis is used to compute the elastic modulus of the coating. An inter-splat correction factor is introduced which considers inter-splat cracks, interface bonding and other effects like curling of splats and splat sliding. After the correction …

Design Of High Temperature Ti–Al–Cr–V Alloys For Maximum Thermodynamic Stability Using Self-Organizing Maps, Rajesh Jha, George S. Dulikravich

Department of Mechanical and Materials Engineering

Data generated for the Ti–Al–Cr–V system of metallic alloys from our previous publication, where the composition of 102 alloys were computationally Pareto optimized with the objective of simultaneously maximizing the Young’s modulus and minimizing density for a range of temperatures, was the starting point of the current research, where compositions at different temperatures of these alloys were analyzed for phase stability in order to generate new data for compositions and volume fractions of stable phases at various temperatures. This resulted in a large dataset where a lot of data were still missing as all the phases are not stable at …

Design Of High Temperature Ti–Al–Cr–V Alloys For Maximum Thermodynamic Stability Using Self-Organizing Maps, Rajesh Jha, George S. Dulikravich

Department of Mechanical and Materials Engineering

Data generated for the Ti–Al–Cr–V system of metallic alloys from our previous publication, where the composition of 102 alloys were computationally Pareto optimized with the objective of simultaneously maximizing the Young’s modulus and minimizing density for a range of temperatures, was the starting point of the current research, where compositions at different temperatures of these alloys were analyzed for phase stability in order to generate new data for compositions and volume fractions of stable phases at various temperatures. This resulted in a large dataset where a lot of data were still missing as all the phases are not stable at …

A Constructal Approach To The Design Of Inflected Airplane Wings, Shanae Powell

FIU Electronic Theses and Dissertations

Aeroelastic instabilities such as flutter can be accurately captured by state-of-the-art aeroelastic analysis methods and tools. However, these tools and methods fall short in exposing the reasons behind the occurrence of such instabilities. In this research, the constructal law is used to discover the main cause of the variation in the flutter speed and stress distribution for inflected aircraft wings when compared to its uninflected counterpart. This law considers the design as a physics phenomenon and uses an evolutionary flow principle to explain and predict the occurrence of energy flow configurations (i.e. the flow of stresses throughout the structure).

For …

Electrochemical Behaviors Of The Electrodes For Proton Conducting Intermediate Temperature Solid Oxide Fuel Cells (It-Sofc), Shichen Sun

FIU Electronic Theses and Dissertations

Proton conducting intermediate temperature (600oC-400oC) solid oxide fuel cells (IT-SOFC) have many potential advantages for clean and efficient power generation from readily available hydrocarbon fuels. However, it still has many unsolved problems, especially on the anode where the fuel got oxidized and the cathode where oxygen got reduced. In this study, for the anode, the effects of hydrogen sulfite (H2S) and carbon dioxide (CO2) as fuel contaminants were studied on the nickel (Ni) based cermet anode of proton conducting IT-SOFC using proton conducting electrolyte of BaZr0.1Ce0.7Y0.1Yb0.1O3 (BZCYYb). Both low-ppm level H2S and low-percentage level CO2 caused similar poisoning effects on …

Modelling, Design, And Optimization Of Membrane Based Heat Exchangers For Low-Grade Heat And Water Recovery, Soheil Soleimanikutanaei

FIU Electronic Theses and Dissertations

Transport Membrane Condenser (TMC) is an innovative technology based on the property of a nano-scale porous material which can extract both waste heat and water from exhaust gases. This technology tremendously improves the efficiency of boilers and gas/coal combustors by lowering waste heat and increasing water recovery. Contaminants in the flue gases, such as CO2, O2, NOx, and SO2 are inhibited from passing through the membrane by the membrane’s high selectivity. The condensed water through these tubes is highly pure and can be used as the makeup water for many industrial applications. The goal of this research is to investigate …

Novel Structural Health Monitoring And Damage Detection Approaches For Composite And Metallic Structures, Shervin Tashakori

FIU Electronic Theses and Dissertations

Mechanical durability of the structures should be continuously monitored during their operation. Structural health monitoring (SHM) techniques are typically used for gathering the information which can be used for evaluating the current condition of a structure regarding the existence, location, and severity of the damage. Damage can occur in a structure after long-term operating under service loads or due to incidents. By detection of these defects at the early stages of their growth and nucleation, it would be possible to not only improve the safety of the structure but also reduce the operating costs. The main goal of this dissertation …

Cfd Evaluation Of Mixing Processes For High-Level Nuclear Waste Tanks, Maximiliano Edrei

FIU Electronic Theses and Dissertations

Computational Fluid Dynamics (CFD) has been applied to investigate two aspects of a mixing process for high level nuclear waste tanks. Through CFD the applicability of Poreh’s correlations that are currently used to describe the radial wall jets in the Pulse Jet Mixing (PJM) process were assessed. In addition, simulations were conducted in order to investigate mean hydrodynamic characteristics of sparged non-Newtonian fluids for the use in the PJM process.

Three single phase turbulent simulations using the commercial package STAR-CCM+ were successively conducted. A model validated with experimental data was developed and successively altered to see effects of low characteristic …

Numerical, Analytical, And Experimental Studies Of Reciprocating Mechanism Driven Heat Loops For High Heat Flux Cooling, Olubunmi Tolulope Popoola

FIU Electronic Theses and Dissertations

The Reciprocating Mechanism Driven Heat Loop (RMDHL) is a novel heat transfer device that utilizes reciprocating flow, either single-phase or two-phase flow, to enhance the thermal management in high tech inventions. The device attains a high heat transfer rate through a reciprocating flow of the working fluid inside the heat transfer device. Although the concept of the device has been tested and validated experimentally, analytical or numerical studies have not been undertaken to understand its working mechanism and provide guidance for the device design. The objectives of this study are to understand the underlying physical mechanisms of heat transfer in …

Effect Of Ultrasonic Treatment On The Microstructure And Mechanical Properties Of Al6061 And Composite, Ana S. Exime

FIU Electronic Theses and Dissertations

In this study, the effect of ultrasonic treatment (UST) parameters such as amplitude, sonication time, and melt temperature on microstructure and microhardness of Al 6061 alloy is evaluated. The effect of UST on the dispersion of tungsten disulfide (WS₂) and carbon nanotubes (CNT) as reinforcement particles in Al 6061 during casting is also studied. The cast Al 6061 with UST demonstrated 32% grain size reduction and 8% increase in the microhardness for optimum processing conditions. The cavitation process induced by UST is responsible for the refinement in microstructure and increase of hardness by enhancing the degassing and nucleation …

Resilient And Real-Time Control For The Optimum Management Of Hybrid Energy Storage Systems With Distributed Dynamic Demands, Christopher R. Lashway

FIU Electronic Theses and Dissertations

A continuous increase in demands from the utility grid and traction applications have steered public attention toward the integration of energy storage (ES) and hybrid ES (HESS) solutions. Modern technologies are no longer limited to batteries, but can include supercapacitors (SC) and flywheel electromechanical ES well. However, insufficient control and algorithms to monitor these devices can result in a wide range of operational issues. A modern day control platform must have a deep understanding of the source. In this dissertation, specialized modular Energy Storage Management Controllers (ESMC) were developed to interface with a variety of ES devices. The EMSC provides …

Detecting Structural Defects Using Novel Smart Sensory And Sensor-Less Approaches, Amin Baghalian

FIU Electronic Theses and Dissertations

Monitoring the mechanical integrity of critical structures is extremely important, as mechanical defects can potentially have adverse impacts on their safe operability throughout their service life. Structural defects can be detected by using active structural health monitoring (SHM) approaches, in which a given structure is excited with harmonic mechanical waves generated by actuators. The response of the structure is then collected using sensor(s) and is analyzed for possible defects, with various active SHM approaches available for analyzing the response of a structure to single- or multi-frequency harmonic excitations. In order to identify the appropriate excitation frequency, however, the majority of …

Development Of Novel, Microscale Fracture Toughness Testing For Adhesives, Dillon S. Watring

FIU Electronic Theses and Dissertations

The purpose of this thesis was to develop microscale fracture toughness tests to be performed in situ based off previously used macroscale fracture toughness tests. The thesis also was to use these tests to perform in situ analysis and imaging of reinforced adhesives during crack propagation. Two different fracture toughness tests were developed for this thesis through developing fixtures and sample geometry. A microscale double cantilever beam (DCB) test was developed for mode I fracture (opening mode). A microscale end notch flexure (ENF) test was developed for mode II fracture (sliding mode).

Three different types of materials were used as …

Robot Control For Remote Ophthalmology And Pediatric Physical Rehabilitation, Melissa Morris

FIU Electronic Theses and Dissertations

The development of a robotic slit-lamp for remote ophthalmology is the primary purpose of this work. In addition to novel mechanical designs and implementation, it was also a goal to develop a control system that was flexible enough to be adapted with minimal user adjustment to various styles and configurations of slit-lamps. The system was developed with intentions of commercialization, so common hardware was used for all components to minimize the costs. In order to improve performance using this low-cost hardware, investigations were made to attempt to achieve better performance by applying control theory algorithms in the system software. Ultimately, …

Design And Control Of A Dynamic And Autonomous Trackless Vehicle Using Onboard And Environmental Sensors, Scott R. Jagolinzer

FIU Electronic Theses and Dissertations

The purpose of this thesis is to explore the current state of automated guided vehicles (AGVs), sensors available for the vehicles to be equipped with, control systems for the vehicles to run on, and wireless technology to connect the whole system together. With a technological push towards increasing automation and maximizing the possible throughput of systems, automated technology needs to improve for trackless and wireless systems such as vehicles that can be used to move loads in a vast array of applications.

The goal of this research is to develop and propose improvements in both vehicle and control system design …