Mechanical Engineering Commons^™

Fault-Tolerant Trajectory Tracking Of Unmanned Aerial Vehicles Using Immunity-Based Model Reference Adaptive Control, Brenton K. Wilburn

Graduate Theses, Dissertations, and Problem Reports (ETD)

This dissertation presents the design, development, and simulation testing of an adaptive trajectory tracking algorithm capable of compensating for various aircraft subsystem failures and upset conditions. A comprehensive adaptive control framework, here within referred to as the immune model reference adaptive control (IMRAC) algorithm, is developed by synergistically merging core concepts from the biologically- inspired artificial immune system (AIS) paradigm with more traditional optimal and adaptive control techniques. In particular, a model reference adaptive control (MRAC) algorithm is enhanced with the detection and learning capabilities of a novel, artificial neural network augmented AIS scheme. With the given modifications, the MRAC …

Electroplating Of Cr-Ni Alloy And Ni-Cr/Ni Multilayer Coatings, Liaowang Liu

Graduate Theses, Dissertations, and Problem Reports (ETD)

The major interests of developing Ni-Cr alloy plating lie in the possible formation of a passive film by chromium and its good chemical and mechanical properties. And nano scale multilayer coatings exhibit improved properties due to nano scale effects (e.g.: high hardness and strength) and they combine and enhance different properties from individual components. Thus, electroplating of Ni-Cr multilayer coatings could have high potential for numerous engineering applications. Electroplating in aqueous and in organic solution by direct current were studied for Ni-Cr alloy coatings, and Ni-Cr multilayer coatings were prepared by pulse current electroplating in single bath.

Traditionally, chromium or …

Computational Investigation Of Rotary Engine Homogeneous Charge Compression Ignition Feasibility, Michael Irvin Resor

Browse all Theses and Dissertations

The Air Force Research Laboratory (AFRL) has been investigating the heavy fuel conversion of small scale Unmanned Aerial Vehicles (UAV). One particular platform is the Army Shadow 200, powered by a UEL Wankel rotary engine. The rotary engine historically is a proven multi-fuel capable engine when operating on spark ignition however, little research into advanced more efficient compression concepts have been investigated. A computational fluid dynamics model has been created to investigate the feasibility of a Homogeneous Charge Compression Ignition (HCCI) rotary engine. This research evaluates the effects, rotor radius to crankshaft eccentricity ratio, known as K factor, equivalence ratio, …

Jump And Pull-In Dynamics Of An Electrically Actuated Bistable Mems Device, Laura Ruzziconi, Stefano Lenci, Mohammad I. Younis

Mechanical Engineering Faculty Scholarship

This study analyzes a theoretical bistable MEMS device, which exhibits a considerable versatility of behavior. After exploring the coexistence of attractors, we focus on each rest position, and investigate the final outcome, when the electrodynamic voltage is suddenly applied. Our aim is to describe the parameter range where each attractor may practically be observed under realistic conditions, when an electric load is suddenly applied. Since disturbances are inevitably encountered in experiments and practice, a dynamical integrity analysis is performed in order to take them into account. We build the integrity charts, which examine the practical vulnerability of each attractor. A …

Pitting Corrosion And Corrosion Fatigue Crack Growth Behavior Of Oil-Grade Alloy 718 In Sodium Chloride Solution, Ting Chen

Graduate Theses, Dissertations, and Problem Reports (ETD)

Oil-grade nickel-base alloy 718 has been recently used in the oil and gas industry for downhole drilling components especially for the parts of the bottom hole assembly (BHA) due to its superior mechanical properties, good corrosion resistance, non-magnetic properties and ability to be heat treated to various strength levels. As the modern oil and gas industry explored into coastal and marine locations, deeper and deeper wells have been drilled with high pressure high temperature, making the demand for increased strength and good toughness super critical for alloys used in ultra-deep wells drilling. Moreover, the existence of high concentrations of chloride …

The Influence Of Mesa Activities On Underrepresented Students Nsf Dr K-12 Proposal 1020019, C. Hailey, Chandra Austin Stallworth, Cameron Denson, Daniel L. Householder

Mechanical and Aerospace Engineering Faculty Publications

Mathematics, Engineering, Science Achievement (MESA) outreach programs are partnerships between K-12 schools and higher education in nine states. MESA efforts introduce integrated experiences in science, mathematics and engineering to K-12 students from groups that are traditionally underrepresented in the STEM disciplines. This exploratory study examined the influence of selected MESA activities on students' self-efficacy, their perceptions of engineering, and their interest in engineering and other STEM fields. Field trips, guest lecturers, design competitions, hands-on activities and student career and academic advisement were of specific interest in this survey. The project also investigated the relationship between student engagement in MESA and …

A Study Of Passenger Car Acoustic Cavity Boom Simulation Methods, Shreerang Dhabe

Dissertations, Master's Theses and Master's Reports - Open

The project objective is the study of acoustic boom phenomenon at 40 Hz in Chevrolet Cruze LTZ and recommend modeling techniques to improve accuracy of model prediction. Acoustic boom is caused by solid-fluid interaction between car structure and air inside the car cavity.

In this report, finite element analysis software Abaqus 6.12-3 is used to simulate the acoustic-structural coupling. The structural and acoustic mesh for the Chevrolet Cruze LTZ are fully coupled and solved using Abaqus ‘strongly coupled’ solution. In order to understand the physics of acoustic boom in a car simple car box models were designed. Simple box car …

Measuring Head Impact Contact Pressure In Collegiate Football Games To Correlate Head Kinematics To Brain Kinetics Elucidating Brain Injury Dynamics, Chandrika S. Abhang

Dissertations, Master's Theses and Master's Reports - Open

Does a brain store thoughts and memories the way a computer saves its files? How can a single hit or a fall erase all those memories? Brain Mapping and traumatic brain injuries (TBIs) have become widely researched fields today. Many researchers have been studying TBIs caused to adult American football players however youth athletes have been rarely considered for these studies, contradicting to the fact that American football enrolls highest number of collegiate and high-school children than adults. This research is an attempt to contribute to the field of youth TBIs.

Earlier studies have related head kinematics (linear and angular …

Military Vehicle Optimization And Control, Denise M. Rizzo

Dissertations, Master's Theses and Master's Reports - Open

It is remarkable that there are no deployed military hybrid vehicles since battlefield fuel is approximately 100 times the cost of civilian fuel. In the commercial marketplace, where fuel prices are much lower, electric hybrid vehicles have become increasingly common due to their increased fuel efficiency and the associated operating cost benefit. An absence of military hybrid vehicles is not due to a lack of investment in research and development, but rather because applying hybrid vehicle architectures to a military application has unique challenges. These challenges include inconsistent duty cycles for propulsion requirements and the absence of methods to look …

Model Updating And Structural Health Monitoring Of Horizontal Axis Wind Turbines Via Advanced Spinning Finite Elements And Stochastic Subspace Identification Methods, Antonio Velazquez Hernandez

Dissertations, Master's Theses and Master's Reports - Open

Wind energy has been one of the most growing sectors of the nation’s renewable energy portfolio for the past decade, and the same tendency is being projected for the upcoming years given the aggressive governmental policies for the reduction of fossil fuel dependency. Great technological expectation and outstanding commercial penetration has shown the so called Horizontal Axis Wind Turbines (HAWT) technologies. Given its great acceptance, size evolution of wind turbines over time has increased exponentially. However, safety and economical concerns have emerged as a result of the newly design tendencies for massive scale wind turbine structures presenting high slenderness ratios …

Evaluation Of Solar Energy Solution For Egyptian Remote Areas, Tarek Ihab Abdelsalam, Tarek M. Hatem

Mechanical Engineering

Egypt is currently suffering the symptoms of the energy crises, such as electricity outage and high deficit as a result of constant increase in fossil foils through the last decades. On the other hand, Egypt has a high solar availability of more than 18.5 MJ annually. Additionally, Egypt has large uninhabited deserts on both sides of the Nile valley and in Sinai Peninsula, which represent more than 96.5% of the nation’s total land area. Therefore, solar energy is one of the prospective solutions for energy shortage in Egypt. Furthermore, these vast lands are advantageous for commissioning huge solar power generation …

Hot Corrosion Behaviour Of New Candidates For Thermal Barrier Coatings Application In Turbine Simulated Environments, Mohammad Hamed Habibi

LSU Doctoral Dissertations

Thermal barrier coatings (TBCs) are used gas turbine engines. The current material of choice (YSZ) degrades when it contacts with impurities arise from low quality fuels such vanadium and sulfur. YSZ cannot be used in temperature higher than 900˚C. Higher efficiency and performance of gas turbine engines will require a new generation of thermal barrier coatings (TBCs). In current work, hot corrosion behavior of new candidates including Gd2Zr2O7, ZrO2 stabilized with Ta2O5, zirconia stabilized with both Ta2O5 and Y2O3 and zirconia stabilized with CeO2 and TiO2 is investigated. For YSZ case, the reaction between NaVO3 and Y2O3 produces YVO4 and …

Probabilistic Engineering Analysis And Design Under Time-Dependent Uncertainty, Zhen Hu

Doctoral Dissertations

"Time-dependent uncertainties, such as time-variant stochastic loadings and random deterioration of material properties, are inherent in engineering applications. Not considering these uncertainties in the design process may result in catastrophic failures after the designed products are put into operation. Although significant progress has been made in probabilistic engineering design, quantifying and mitigating the effects of time-dependent uncertainty is still challenging. This dissertation aims to help build high reliability into products under time-dependent uncertainty by addressing two research issues. The first one is to efficiently and accurately predict the time-dependent reliability while the second one is to effectively design the time-dependent …

Modeling And Simulation Of Continuous Fiber-Reinforced Ceramic Composites, Venkata Bheemreddy

Doctoral Dissertations

"Finite element modeling framework based on cohesive damage modeling, constitutive material behavior using user-material subroutines, and extended finite element method (XFEM), are developed for studying the failure behavior of continuous fiber-reinforced ceramic matrix composites (CFCCs) by the example of a silicon carbide matrix reinforced with silicon carbide fiber (SiC/SiCf) composite. This work deals with developing comprehensive numerical models for three problems: (1) fiber/matrix interface debonding and fiber pull-out, (2) mechanical behavior of a CFCC using a representative volume element (RVE) approach, and (3) microstructure image-based modeling of a CFCC using object oriented finite element analysis (OOF). Load versus displacement behavior …

Modeling And Simulation Of Hydrokinetic Composite Turbine System, Haifeng Li

Doctoral Dissertations

"The utilization of kinetic energy from the river is promising as an attractive alternative to other available renewable energy resources. Hydrokinetic turbine systems are advantageous over traditional dam based hydropower systems due to "zero-head" and mobility. The objective of this study is to design and analyze hydrokinetic composite turbine system in operation. Fatigue study and structural optimization of composite turbine blades were conducted. System level performance of the composite hydrokinetic turbine was evaluated. A fully-coupled blade element momentum-finite element method algorithm has been developed to compute the stress response of the turbine blade subjected to hydrodynamic and buoyancy loadings during …

Cryogenic Testing Of High-Velocity Spoke Cavities, C. S. Hopper, Hyekyoung Park, J. R. Delayen

Physics Faculty Publications

Spoke-loaded cavities are being investigated for the high-velocity regime. The relative compactness at low-frequency makes them attractive for applications requiring, or benefiting from, 4 K operation. Additionally, the large velocity acceptance makes them good candidates for the acceleration of high-velocity protons and ions. Here we present the results of cryogenic testing of a 325 MHz, β0 = 0.82 single-spoke cavity and a 500 MHz, β0 = 1 double-spoke cavity.

Multipacting Optimization Of A 750 Mhz Rf Dipole, A. Castilla, J. R. Delayen

Physics Faculty Publications

Crab crossing schemes have been proposed to re-instate luminosity degradation due to crossing angles at the interaction points in next generation colliders to avoid the use of sharp bending magnets and their resulting large synchrotron radiation generation, highly undesirable in the detector region. The rf dipole has been considered for a different set of applications in several machines, both rings and linear colliders. We present in this paper a study of the effects on the multipacting levels and location depending on geometrical variations on the design for a crabbing/deflecting application in a high current (3/0.5 A), high repetition (750 MHz) …

Crack Self-Healing In Sic/Spinel Nanocomposite, Fariborz Tavangarian

LSU Doctoral Dissertations

Spinel is one of the best known and widely used ceramic materials. It has good thermal shock resistance, high chemical inertness in both acidic and basic environments, excellent optical and dielectric properties, high strength at both elevated and normal temperatures, and has no phase transition up to the melting temperature (2135°C). Spinel is used in the metallurgical, electrochemical, and chemical industrial fields. It has also found some applications in dentistry, catalyst supports, humidity sensors, reinforcing fibers, photoluminescent materials, etc. One of the limitations of spinel ceramic is its brittleness. Furthermore, at high temperature applications, a rapid heating or cooling can …

Applications Of The Variational Approach To Fracture Mechanics, Ataollah Mesgarnejad

LSU Doctoral Dissertations

In this study we present the variational approach to fracture mechanics as a versatile tool for the modeling of the fracture phenomenon in solids. Variational fracture mechanics restates the problem of initiation and propagation of cracks in solids as an energy minimization problem. The edifice of this energy minimization problem is such that unlike other methods (e.g. extended finite element method XFEM, cohesive-zone methods) the variational approach to fracture mechanics, diminishes the need for an a priori knowledge of the crack path or ad hoc assumptions in the form of path selection laws. We will show applications of the variational …

Unidirectional Rotary Tendency Of A Wave-Driven Rotor, Yingchen Yang

Mechanical Engineering Faculty Publications

Ocean waves can directly drive WECs (wave energy converters) to perform two types of motion—reciprocating motion and unidirectional rotary motion. In general, the efficiency of a reciprocating WEC is strongly wave-frequency dependent, whereas the efficiency of a rotary WEC can be somewhat wave-frequency independent. To date, a huge majority of WEC technologies under development in industry belong to the reciprocating class, and only a few WEC concepts fall in the unidirectional rotary class. In the present work, a wave-driven rotor for unidirectional rotary motion was proposed and characterized. A numerical tool has been developed for characterization of the rotor’s unidirectional …

Neuromodulation Based Control Of Autonomous Robots On A Cloud Computing Platform, Cameron Muhammad

College of Graduate Studies: Theses & Dissertations

In recent years, the advancement of neurobiologically plausible models and computer networking has resulted in new ways of implementing control systems on robotic platforms. The work presents a control approach based on vertebrate neuromodulation and its implementation on autonomous robots in the open-source, open-access environment of robot operating system (ROS). A spiking neural network (SNN) is used to model the neuromodulatory function for generating context based behavioral responses of the robots to sensory input signals. The neural network incorporates three types of neurons- cholinergic and noradrenergic (ACh/NE) neurons for attention focusing and action selection, dopaminergic (DA) neurons for rewards- and …

Novel Syntheses And Surface Modifications Of Electrode Materials For Superior Lithium-Ion Batteries, Jianqing Zhao

LSU Doctoral Dissertations

Rechargeable lithium-ion battery is one of the most promising energy conversion and storage systems that offers high energy and powder densities, long service life and assuring safety. Performance of lithium-ion batteries crucially relies on electrochemical characteristics of electrode materials, i.e., anode and cathode materials. This dissertation work aims at developing novel electrode materials with high capacity, excellent cycling stability and remarkable rate capability for next-generation lithium-ion batteries. The effects of surface modifications for LiMn2O4 cathode materials are studied by depositing ultrathin conformal amphoteric oxides via atomic layer deposition (ALD). In the case of ZnO coating, the thickness of ZnO ALD …

The Effect Of Surface Corrosion Damage On The Fatigue Life Of Extruded Aluminum Alloy 6061-T6, Matthew Weber

UNF Graduate Theses and Dissertations

Aluminum alloy 6061-T6 is a common engineering material used in aerospace, automotive, structural applications. Despite its wide use, little has been published about the effects of damage from surface corrosion on its fatigue life. An investigation was performed where 6061-T6 extrusions were exposed to a 3.5% NaCl solution at pH 2 for 2 days and 24 days. The length of time and pH were chosen in order to create distinct surface flaws. The effect of these flaws on the fatigue life was then investigated and analyzed using scanning electron microscopy (SEM) and Weibull statistics. It was determined that samples corroded …

Predicting Pressure Distribution Between Transfemoral Prosthetic Socket And Residual Limb Using Finite Element Analysis, Rajesh Surapureddy

UNF Graduate Theses and Dissertations

In this study, a non-linear Finite Element (FE) model was created and analyzed to determine the pressure distribution between the residual limb and the prosthetic socket of a transfemoral amputee. This analysis was performed in an attempt to develop a process allowing healthcare providers and engineers to simulate the fit and comfort of transfemoral prosthetics to reduce the number of re-fittings needed for the amputees. The analysis considered the effects of interference due to insertion of the limb into the prosthesis, referred to as donning, and also the effects due to the body weight of the amputee. A non-linear finite …

Modeling Of Chemical-Mechanical Couplings In Solid Oxide Cells And Reliability Analysis, Xinfang Jin

Theses and Dissertations

Solid oxide fuel cell (SOFC) has been well demonstrated as a promising clean energy conversion technology. For practical applications, the SOFC systems should have both good electrochemical performance and high reliability. The SOFCs are usually operated under very aggressive conditions, e.g., high temperatures (600-1000oC) and extremely low oxygen partial pressures (anode electrode). These aggressive operating conditions could lead to a variety of material system degradations, imposing great challenges on meeting lifetime requirement of SOFC commercial applications. It is therefore essential to increase the understanding of fundamental SOFC degradation mechanisms.

The basic structure of SOFCs is a positive electrode-electrolyte-negative electrode (PEN) …

Material Synthesis And Fabrication Method Development For Intermediate Temperature Solid Oxide Fuel Cells, Hanping Ding

Theses and Dissertations

Solid oxide fuel cells (SOFCs) are operated in high temperature conditions (750-1000 oC). The high operating temperature in turn may lead to very complicated material degradation issues, significantly increasing the cost and reducing the durability of SOFC material systems. In order to widen material selections, reduce cost, and increase durability of SOFCs, there is a growing interest to develop intermediate temperature SOFCs (500-750 oC). However, lowering operating temperature will cause substantial increases of ohmic resistance of electrolyte and polarization resistance of electrodes. This dissertation aimed at developing high-performance intermediate-temperature SOFCs through the employment of a series of layered perovskite oxides …

Measuring The Effectiveness Of Education For Sustainable Development Interventions For Effecting Change In Knowledge, Attitude And Behaviors Toward Sustainable Development, Christopher Robin Wilson

Theses and Dissertations

The question addressed by this study is whether an intervention involving a brief, focused seminar providing Sustainability Fundamental education can affect change in sustainability-centric behavior via measured change in attitude toward sustainability and/or change knowledge of sustainability fundamentals.

This study focused on applying and extending lessons from a previous exploration of the relationships between sustainable behavior and both attitude toward sustainability and knowledge of sustainability. The test involved determining whether brief, science-based sustainability fundamentals seminars are an effective intervention for affecting the favorable sustainable behavior of practicing engineers, defined as professionals engaged in engineering post-completion of their formal studies, in …

A Study On The Role Of Physical Models In The Mitigation Of Design Fixation, Vimal Viswanathan, Olufunmilola Atilola, Nicole Esposito, Julie Linsey

Faculty Publications, Mechanical Engineering

Designers implement a variety of models and representations during the design process, yet little is known about the cognitive impacts of various representations. This study focuses on how physical models can assist novices in mitigating design fixation on undesirable features. During idea generation, designers tend to fixate on examples they encounter or on their own initial ideas. The first hypothesis states that designers tend to duplicate features of provided examples. The second hypothesis states that this fixation can be mitigated with appropriate warnings. The last hypothesis is that building and testing physical models can help designers in mitigating fixation. To …

Heat Transfer Enhancement By Three-Dimensional Surface Roughness Technique In Nuclear Fuel Rod Bundles, Kang Liu

Theses and Dissertations

DISS_abstract> This thesis investigate thermal characteristic of a single-phase nano-fluid in a single heater element loop tester and provides a comparison between heat transfer enhancement results achieved using water as a coolant and using nano-fluids with different volume percentage. The experimental investigation is performed on two simulated nuclear fuel rods with two different types of modified outer surfaces roughness. The fuel rod surfaces modified are termed as two-dimensional surface roughness (square transverse ribbed surface) and three-dimensional surface roughness (Diamond shaped blocks). The nano-fluid used are 0.5% and 2% ZnO-Deionized water based nano-fluid. The maximum heat transfer co-efficient enhancement achieved compared …

Performance Evaluation Of Polyurethane Composites Using Vacuum Infusion Process, Mohaned M. Mohamed

Doctoral Dissertations

"Glass fiber-reinforced polymer composites have promising applications in infrastructures due to their low cost, high specific stiffness/strength, and corrosion resistance. The pultrusion process is often used to manufacture glass fiber-reinforced polyurethane (PU) composite. The objective of this study is to use thermoset PU resin to manufacture high quality composites for infrastructure applications using vacuum assisted resin transfer molding (VARTM) process. Using VARTM to fabricate PU resins presents unique challenges. Several modifications however have helped with overcoming these problems. In part I of the research, the mechanical performance of two different PU resin not only evaluated but also compared to one …