Mechanical Engineering Commons^™

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 …