Mechanical Engineering Commons^™

A Non-Equilibrium Molecular Dynamics Study Of The Effects Of Helium Bubbles On The Thermal Conductivity Of Zrc, Tate Shorthill

All Graduate Plan B and other Reports, Spring 1920 to Spring 2023

Zirconium carbide (ZrC) has been proposed as a potential improvement to nuclear fuel cladding. As such, it is important to characterize its physical properties, particularly those relating to thermal energy transport. Reactor conditions are known to damage fuel microstructure over time. While research has been conducted on undamaged and damaged ZrC, some areas of interest remain. Fission products, such as helium, can accumulate in pores within the fuel microstructure. Such a case has yet to be characterized in ZrC fuel cladding.

A non-equilibrium molecular dynamics model was developed to characterize the thermal properties of ZrC. Fourier’s Law allows the thermal …

High Dynamic Range Optical Devices And Applications., Elijah Robert Jensen

Electronic Theses and Dissertations

Much of what we know about fundamental physical law and the universe derives from observations and measurements using optical methods. The passive use of the electromagnetic spectrum can be the best way of studying physical phenomenon in general with minimal disturbance of the system in the process. While for many applications ambient visible light is sufficient, light outside of the visible range may convey more information. The signals of interest are also often a small fraction of the background, and their changes occur on time scales so quickly that they are visually imperceptible. This thesis reports techniques and technologies developed …

Command Governor-Based Adaptive Control For Dynamical Systems With Matched And Unmatched Uncertainties, Metehan Yayla, Ehsan Arabi, Ali Turker Kutay, Tansel Yucelen

Mechanical and Aerospace Engineering Faculty Research & Creative Works

In this paper, we propose a command governor-based adaptive control architecture for stabilizing uncertain dynamical systems with not only matched but also unmatched uncertainties and achieving the desired command following performance of a user-defined subset of the accessible states. In our proposed solution, online least-squares solutions for the matched and unmatched parameters are obtained through integration method and they are employed in the adaptive control framework. Specifically, the matched uncertainty is identified and its effect upon the system behavior is entirely attenuated. Moreover, using the unmatched uncertainty approximation obtained through radial basis function neural networks, the command governor signal is …

The Development And Validation Of Sinatra: A Three-Dimensional Direct Simulation Monte Carlo (Dsmc) Code Written In Object-Oriented C++ And Performed On Cartesian Grids, David Matthew Galvez

Master's Theses

The field of Computational Fluid Dynamics (CFD) primarily involves the approximation of the Navier-Stokes equations. However, these equations are only valid when the flow is considered continuous such that molecular interactions are abundant and predictable. The Knudsen number, $Kn$, which is defined as the ratio of the flow's mean free path, $\lambda$, to some characteristic length, $L$, quantifies the continuity of any flow, and when this parameter is large enough, alternative methods must be employed to simulate gases. The Direct Simulation Monte Carlo (DSMC) method is one which simulates rarefied gas flows by directly simulating the particles that compose the …

Decomposition And Ionization Of Ionic Liquids, Forrest Grady Kidd Iii

Dissertations

The United States Air Force is interested in developing a situationally responsive space environment. In order to achieve this, dual-mode-propulsion will be utilized. A new class of propellants is being developed for this application based on energetic ionic liquids. Two ionic liquids of current interest are Hydroxylammonium Nitrate (HAN) and Hydroxyethylhydrazinium Nitrate (HEHN) due to their beneficial performance characteristics. The decomposition and ionization chemistry of these two species is investigated in this work. Using GAUSSIAN09 software, reactions with important radicals are explored through quantum chemistry. The energetics of reactions as well as the identity of key product complexes are given. …

Molecular Dynamics Simulation Study On The Possible Factors Affecting Stability Of Ods Steel, M. Mustafa Azeem, Zhongyu Li, Qingyu Wang, Abid Hussian

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

Oxide-dispersed-strengthened (ODS) steel has excellent mechanical, thermodynamic and radiation resistant properties, which makes it an important candidate material for high-Temperature reactors applications. Radiation stability of oxide is very important to study at the atomic level. In present case molecular dynamics (MD) simulation is used to study stabilities of Y₂O₃ particles in ODS steel as a function of particle sizes. The size dependence is obvious for particle sizes larger than 2.8 nm. Furthermore, the stabilities depend on charges of Y and O atoms.

Considerations For Atmospheric Measurements With Small Unmanned Aircraft Systems, Jamey D. Jacob, Phillip B. Chilson, Adam L. Houston, Suzanne Weaver Smith

Mechanical Engineering Faculty Publications

This paper discusses results of the CLOUD-MAP (Collaboration Leading Operational UAS Development for Meteorology and Atmospheric Physics) project dedicated to developing, fielding, and evaluating integrated small unmanned aircraft systems (sUAS) for enhanced atmospheric physics measurements. The project team includes atmospheric scientists, meteorologists, engineers, computer scientists, geographers, and chemists necessary to evaluate the needs and develop the advanced sensing and imaging, robust autonomous navigation, enhanced data communication, and data management capabilities required to use sUAS in atmospheric physics. Annual integrated evaluation of the systems in coordinated field tests are being used to validate sensor performance while integrated into various sUAS platforms. …

Effects Of Automated Fiber Placement On High Strain Rate Compressive Response Of Advanced Composites, Alexander Trochez

Mechanical & Aerospace Engineering Theses & Dissertations

Automated Fiber Placement (AFP) technology shows great promise in manufacturing carbon fiber composite structures. However, intermittent defects occur in the process that can affect the overall mechanical performance of the structure. The aim of this work is to investigate the effects of deliberately placed principal defects (Gap, Overlap, and Fold) on the compressive response under quasistatic (strain rate ~10^-3 s^-1) and dynamic (strain rate ~10³ s-1) loading conditions. The controlled defects were placed at the laminate level in different orientations and depths. High strain rate compression experiments were conducted using a split Hopkinson pressure bar (SHPB) …

Catalytic Augmentation Of An Arc-Ignited Hydrogen Peroxide/Abs Hybrid Rocket System, Stephen A. Whitmore, Christopher J. Martinez

Mechanical and Aerospace Engineering Faculty Publications

The authors have collaborated with an industry partner to develop a prototype upper stage for a dedicated nano-launch vehicle. In addition to providing sufficient impulse for orbit insertion, the unique motor system also provides capability for multiple restarts; allowing operation as an orbital maneuvering thruster. The hybrid motor design uses 85%-90% hydrogen peroxide solution and 3-D printed ABS as propellants. In the original system design the peroxide catalyst bed was completely removed and a patented arc-ignition system thermally ignited the propellants. The thermal ignition system was effective but resulted in a combustion latency of approximately 1-second, reducing overall performance and …

Simulation Of Radiation Flux From Thermal Fluid In Origami Tubes, Robert R. Bebeau

USF Tampa Graduate Theses and Dissertations

Spacecraft in orbit experience temperature swings close to 240 K as the craft passes from the shadow of the Earth into direct sunlight. To regulate the craft’s internal energy, large radiators eject unwanted energy into space using radiation transfer. The amount of radiation emitted is directly related to the topology of the radiator design. Deformable structures such as those made with origami tessellation patterns offer a mechanism to control the quantity of energy being emitted by varying the radiator shape. Three such patterns, the Waterbomb, Huffman Waterbomb, and Huffman Stars-Triangles, can be folded into tubes. Origami tubes offer greater control …

Thermal Modelling And Validation Of Heat Profiles In An Rf Plasma Micro-Thruster, Alec Sean Henken

Master's Theses

The need and demand for propulsion devices on nanosatellites has grown over the last decade due to interest in expanding nanosatellite mission abilities, such as attitude control, station-keeping, and collision avoidance. One potential micro-propulsion device suitable for nanosatellites is an electrothermal plasma thruster called Pocket Rocket. Pocket Rocket is a low-power, low-cost propulsion platform specifically designed for use in nanosatellites such as CubeSats. Due to difficulties associated with integrating propulsion devices onto spacecraft such as volume constraints and heat dissipation limitations, a characterization of the heat generation and heat transfer properties of Pocket Rocket is necessary. Several heat-transfer models of …

Microfluidic Biosensor With Functionalized Gold Nano Particles On Interdigitated Electrodes, Bharath Babu Nunna

Dissertations

The integration of the microfluidics to the biosensor has growing demand with favorable conditions such as reduced processing time and low reagent consumption. The immuno biosensing with the microfluidic platform helped to make the electrochemical biosensing assays portable due to which this sensing mechanism can be easily implemented in point of care devices. The implementation of the biosensing in the microchannels significantly reduces the sample requirement form milli liter (mL) to micro liter (uL), and thus leads to low volume sample requirement during the sensing. The primary factors contributing to the microfluidic biosensors performance are probe immobilization, specific binding and …

Numerical Assessment Of The Convective Heat Transfer In Rotating Detonation Combustors Using A Reduced-Order Model, James Braun, Jorge Sousa, Guillermo Paniagua

School of Aeronautics and Astronautics Faculty Publications

The pressure gain across a rotating detonation combustor offers an efficiency rise and potential architecture simplification of compact gas turbine engines. However, the combustor walls of the rotating detonation combustor are periodically swept by both detonation and oblique shock waves at several kilohertz, disrupting the boundary layer, resulting in a rather complex convective heat transfer between the fluid and the solid walls. A computationally fast procedure is presented to calculate this extraordinary convective heat flux along the detonation combustor. First, a numerical model combining a two-dimensional method of characteristics approach with a monodimensional reaction model is used to compute the …

Fracture Initiation In A Transversely Isotropic Solid: Transient Three Dimensional Analysis, Louis Milton Brock

Mechanical Engineering Faculty Publications

A transversely isotropic solid is at rest, and contains a semi-infinite, plane crack. The axis of rotational material symmetry lies in the crack plane. Application of normal point forces to each face of the crack causes transient 3D growth. The related problem of discontinuities in displacement and traction that exist on regions that exhibit dynamic similarity is first considered. Analytic results are obtained in integral transform space. These lead to equations of the Wiener–Hopf type for the fracture problem. Analytic solutions are again obtained and, upon inversion, subjected to a dynamic energy release rate criterion that includes kinetic energy. A …

Tutorial: Determination Of Thermal Boundary Resistance By Molecular Dynamics Simulations, Zhi Liang, Ming Hu

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Due to the High Surface-To-Volume Ratio of Nanostructured Components in Microelectronics and Other Advanced Devices, the Thermal Resistance at Material Interfaces Can Strongly Affect the overall Thermal Behavior in These Devices. Therefore, the Thermal Boundary Resistance, R, Must Be Taken into Account in the Thermal Analysis of Nanoscale Structures and Devices. This Article is a Tutorial on the Determination of R and the Analysis of Interfacial Thermal Transport Via Molecular Dynamics (MD) Simulations. in Addition to Reviewing the Commonly Used Equilibrium and Non-Equilibrium MD Models for the Determination of R, We Also Discuss Several MD Simulation Methods Which Can Be …

A Microresonator-Based Laser Doppler Velocity Sensor For Interplanetary Atmospheric Re-Entry, Benjamin Wise

Mechanical Engineering Research Theses and Dissertations

In this thesis, a laser velocity sensor concept based on optical microresonators is presented and the application to spacecraft atmospheric entry is explored. The concept is based on the measurement of Doppler shift of back-scattered laser light. Specifically, the Doppler shift is detected by observing the whispering gallery optical modes (WGM) of a dielectric microresonator excited by the back scattered light from particulates and gas molecules. The microresonator replaces the typical Fabry-Perot interferometer and CCD camera system, thereby significantly reducing the size and weight of the overall detection system. This thesis presents proof-of-concept results for this measurement approach. The Doppler …

Active Vibration Control Of Helicopter Rotor Blade By Using A Linear Quadratic Regulator, Md Mosleh Uddin

LSU New Orleans Theses and Dissertations

Active vibration control is a widely implemented method for the helicopter vibration control. Due to the significant progress in microelectronics, this technique outperforms the traditional passive control technique due to weight penalty and lack of adaptability for the changing flight conditions. In this thesis, an optimal controller is designed to attenuate the rotor blade vibration. The mathematical model of the triply coupled vibration of the rotating cantilever beam is used to develop the state-space model of an isolated rotor blade. The required natural frequencies are determined by the modified Galerkin method and only the principal aerodynamic forces acting on the …

Experimental Investigation Of Fischer-Tropsch Synthesis With A Modified Catalyst Support, Pawarat Bootpakdeetam

Mechanical and Aerospace Engineering Dissertations - Archive

Energy demand has been rapidly increasing in the last 30 years due to the population growth and high demand by industries. However, as natural energy sources are limited, they cannot meet this increased energy demand. Therefore, alternative energies have become an option to sustain current and future energy demands. One promising and reliable alternative energy is the Fischer-Tropsch synthesis (FTS), which is a gas-to-liquid (GTL) technology that converts syngas from a low-value feedstock, for example, from coal, biomass, or natural gas, into a high-value liquid hydrocarbon. In addition, FTS is a highly exothermic catalytic reaction that requires careful thermal management …

Reconfigurable Electrochemical Biosensor Enabled By Digital Microfluidic Devices, Ali Farzbod

Mechanical and Aerospace Engineering Dissertations - Archive

The increasing demand for improving the health care quality in developed countries with synchronous advances in the microfabrication of CMOS devices results in the emergence of the Lab-on-a-chip (LOC) field. The ultimate goal of LOC's is to achieve the complete integration of biomedical protocols, such as sample pre-processing and separation and analysis of biosamples on a chip. Electrowetting on dielectric (EWOD) as a distinctive digital microfluidic (DMF) is capable of manipulating droplets less than a microliter along the electrode arrays by applying AC voltages. EWOD chips, as microfluidic platforms, are inherently electrical and do not have to deal with problems …

A Two Stage Event Based Data Driven Controller For Improved Grasping Of An Artificial Hand, Christopher Abrego

Mechanical and Aerospace Engineering Dissertations - Archive

The human hand is one of the greatest (if not the greatest) tool known to mankind for grasping objects. So much so, that researchers have been investigating the development of artificial biomimetic hands in an effort to mimic their functionality and dexterity with the indent to apply the technology to various robotic platforms; ranging from end effectors for industrial pick-and-place robotics, to upper-limb prosthetics, to humanoids. There are certain features that make this endeavor challenging such as the mechanical design, actuation and sensorization, and functionality as well as the interaction from both the view point of interacting with an end …

Finite Element Analysis Of Composite Water Buffer Drum, Chinmay Shrikrishna S Godbole

Mechanical and Aerospace Engineering Theses - Archive

Composite materials offer many advantages for to many industries and developments based on their low density, corrosion resistance, and high strength to weight ratio. In addition, the use of composites allows for more design flexibility for products, the properties to meet specific design requirements, thus promoting better system oriented and cost-effective solutions. However, on a high performance equated basis, the economic incentive to use composite components can often be demonstrated based on their capability to reduce system and life cycle costs. Water buffer drum which is a pressure vessel holds a specified volume of fluid with desired temperature and pressure. …

On The Development And Integration Of Pneumatic Extrusion Module And A Methodology To Identify Process Parameters For Additive Manufacturing Using Machine Learning, Kashish Dhal

Mechanical and Aerospace Engineering Theses - Archive

Commonly used additive manufacturing platforms have a single extrusion module based on Fused Filament Fabrication (FFF) and their processing software generates G-Codes for this FFF module using defined process parameters. These platforms and software do not accommodate different processing modules such as viscous extruders or Direct Ink Writing (DIW). This research is focused on the development of a Pneumatic Extrusion Module (PEM) capable of dispensing viscous materials such as gels or slurries controlled through a digital pneumatic valve. A PEM is developed, integrated and its performance is evaluated on a multi-modality additive manufacturing platform in the MARS Lab. The operation …

Experimental Analysis Of A Single-Phase Direct Liquid Cooled Server Performance At Extremely Low Temperatures For Extended Time Periods, Gautam Gupta

Mechanical and Aerospace Engineering Theses - Archive

A data center is a centralized facility that we use for housing the computer systems and its related components such as high-end servers, redundant data connection and security controls. The next radical change in the thermal management of data centers is to shift from conventional cooling methods like air-cooling to direct liquid cooling (DLC) to deal with high thermal mass. The past few years have consistently seen wider adoption of direct liquid cooling because of its simplicity and high heat dissipation capacity. Passive single phase engineered fluid immersion cooling has several other benefits like better server performance, even temperature profile …

Quasi-One-Dimensional Scramjet Combustor Flow Solver Using The Numerical Propulsion System Simulation, Long Vu

Mechanical and Aerospace Engineering Theses - Archive

The flow field inside a scramjet engine combustor involves complex phenomena such as fuel-air mixing, combustion chemistry, and flow separation. In order to determine the properties of the flow along the length of the combustor, mass, momentum and energy balance equations are solved simultaneously using a numerical method. While a full three dimensional computational simulation gives detailed results with high order of accuracy, it demands a great amount of time and computational resource. A low order analysis produces a fast overall picture of the combustor operation which in turn provides valuable information suitable for the preliminary design process. This research …

Robot Motion Tracking Using Time-Of-Flight And Structured Light Sensors For Indoor Navigation, Karan Vishnu Rao

Mechanical and Aerospace Engineering Theses - Archive

Simultaneous localization and mapping for mobile robots has been an active research field for several years with focus on the problems of accuracy and dependability of the data from the robot's peripherals. The position estimates for mobile and industrial robots is usually achieved by using the information from the global positioning system in an outdoor environment and for indoor environment, technologies such as LiDAR sensors and Infrared (IR) camera based motion capture systems such as VICON (TM) are used. The main issue with these approach for indoor navigation is the monetary cost to associated with these technologies. The purpose of …

Comparison Of Carbon Steel And Composite Side Wall Of Light Rail Vehicle By Finite Element Analysis, Dilraj Singh

Mechanical and Aerospace Engineering Theses - Archive

A Railroad car is a vehicle used for carrying passengers and cargo. In the modern era, rail vehicles are designed as lightweight structures with the aim to minimize mass, operational energy demands, and CO2 emissions. Light rail vehicle is used at street level where they have direct contact with normal traffic and have a short distance between stations. In order to reduce dwell time at stops, and so, the vehicle can accelerate and deaccelerate easily, weight should be less and that is why low floor design is adopted these days. The sidewall is a crucial part of the car body …

Airflow Path And Flow Pattern Analysis Of Sub-Micron Particulate Contaminants In A Data Center With Hot Aisle Containment System Utilizing Direct Air Cooling, Satyam Saini

Mechanical and Aerospace Engineering Theses - Archive

The percentage of the energy used by data centers for cooling their equipment has been on the rise. With it has been the necessity for exploring new and more efficient methods, both from an engineering as well as business point of view, to contain this energy demand. The PCB boards are becoming more densely populated with multitude of smaller hardware on them, thereby, increasing its cooling requirements. Literature suggests that almost 40% of the total energy consumption in a typical Data Center is used for cooling purposes. Air cooling has always been the first choice for IT companies to cool …

Experimental Characterization Of Vertically Split Distribution Wet- Cooling Media Used In Direct Evaporative Cooling Of Data Center, Ahmed Al Khazraji

Mechanical and Aerospace Engineering Theses - Archive

When operating in direct evaporative cooling (DEC) mode, the amount of moisture added to a system can be controlled by frequently modulating water supply to the wet cooling media. Though many challenges arise due to geographical and site conditions, this concept can be applied to data centers to serve as a cost-effective alternative for maintaining the operating temperature of the facility at any weather condition. However, this method results in scale and mineral build up on the media because of an irregular water distribution. To prevent the scale formation, the operators allow the water supply continuously on the cooling media …

Investigation On Effective Modulus And Stress Concentration Factor Of 3d Reinforced Composite By Finite Element Analysis Method, Chandra Bhaskar Reddy Pittu

Mechanical and Aerospace Engineering Theses - Archive

Micromechanics of Composites aims to analyze the localized stresses inside any given constituents of the composite structure. This Thesis is focused on Calculating the effective modulus and the Stress concentration factor of the 3D straight Fiber Composite using Finite Element(FE). The compressive and a Shear response of a 3D Straight fiber composite comprising three directional E Glass Fibers reinforced in an epoxy matrix is analysed. This result is the 10% of overall Composite Ductility and a 10% of overall Shear displacement load in the orthogonal directions. FE calculations are reported to analyse the response of 3d reinforcement as of with …

Optimization Of Heating, Ventilation, And Air-Conditioning (Hvac) Chilled Water Plant Systems, Cliff Odhiambo Nudi

Mechanical and Aerospace Engineering Theses - Archive

Heating, Ventilation, and Air-conditioning accounts for about 60% of the total energy consumed in commercial facilities including office buildings, hospitals, retail stores, warehouses, campuses, manufacturing facilities, medical facilities, etc. As the cost of electricity and energy continue to rise, building owners and facility managers continue to witness a rise in the Total Cost of Ownership. Chilled water plant system is the largest consumer of energy in HVAC system consuming 75% of the total energy used in HVAC according to the Department of Energy. Operating chilled water plant systems at the recommended AHRI Standard 550/590 for performance rating of water chilling …