Mechanical Engineering Commons^™

Optimization Of Heat Sinks In A Range Of Configurations., Archibald Allswell Amoako

Electronic Theses and Dissertations

In this study, different heatsink geometries used for electronic cooling are studied and compared to each other to determine the most efficient. The goal is to optimize heat transfer of the heat sinks studied in a range of configuration based on fin geometry. Heat sinks are thermal conductive material devices designed to absorb and disperse heat from high-temperature objects (e.g. Computer CPU). Common materials used in the manufacturing of heat sinks are aluminum and copper due to their relatively high thermal conductivity and lightweight [1]. Aluminum is used as the material for the heatsinks studied in this research project. To …

Uncertainty In Combustion Reaction Rates And Its Effects On Combustion Simulations, Joshua Piehl

Wayne State University Theses

This work investigates the uncertainties in reaction rates of an n-dodecane model on turbulent spray combustion simulations. Six major reactions were found to significantly impact the ignition delay of the mechanism in a 0-D batch reactor model. These reactions’ rates were independently modified and placed into individual mechanisms. These newly developed mechanisms were simulated in a 3-D turbulent spray simulation and a 0-D batch reactor at a pressure of 60 bar and temperatures from 900 to 1100 K. The combustion characteristics (e.g. ignition delays, flame lift-off length, liquid and vapor penetration) of the modified mechanisms were compared to those produced …

Hydrogen Fuel Cells, Sydney Pilgrim, Skyler Smith

ENgaging Educators in Renewable enerGY (ENERGY): Lesson Plans & Slideshows (2017-2019)

Hydrogen fuel cells are hydrogen powered energy sources. They convert chemical energy into electrical energy by separating water molecules into the two elements that make up water, Hydrogen (2) and Oxygen (1). Hydrogen fuel cells are looking to become a paramount energy producer to avoid consuming fossil fuels for power. Along with the abundance of Hydrogen in the atmosphere being a benefit of using Hydrogen powered fuel cells, the only emission from these energy sources is water vapor. Many car engines only operate at a 20% fuel efficiency, whereas fuel cell powered cars utilize 60% of the energy produced. Although …

Solar Tracking Sustainable Energy Education, Tara Hart, Donita Legonas

ENgaging Educators in Renewable enerGY (ENERGY): Lesson Plans & Slideshows (2017-2019)

Two middle school science teachers collaborated with Georgia Southern lab students to conduct research and experimentation on the benefits of utilizing a dual-axis solar tracking system to assess the amount of voltage received during various times of the day. A smaller similar dual-axis solar tracking system was designed and fabricated to utilize in the teachers’ middle school classrooms in the study of renewable energy and the engineering and design process.

Including Topographical Effects In Slant-Range Modeling, Kari C. Ward, Kyle J. Demarsy

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Spacecraft descent-to-landing navigation often includes the use of a slant-range measurement, the distance from the spacecraft to a surface along the off-nadir pointing direction of the sensor. Modeling a slant range sensor requires a reference surface, approximations of which include spherical and ellipsoidal surfaces, spherical harmonic models, and topographical maps based on prior reconnaissance data. For the spherical and ellipsoidal reference surfaces, a closed-form solution of the slant-range measurement exists. However, these approaches are inaccurate with respect to the true surface. This paper develops a method to implement digital elevation maps of a given surface to create a topography-based model …

Electric Solid Propellant Ablation In A Pulsed Electric Thruster, Matthew S. Glascock, Joshua L. Rovey

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Electric solid propellants are advanced solid chemical rocket propellant that can be controlled (ignited, throttled and extinguished) with electric current. Work reported here focuses on application of electric solid propellant in a pulsed electric thruster similar to a pulsed plasma thruster. In the future it may be possible to develop a dual-mode electric solid propellant thruster that is switchable between steady applied electric current chemical mode and pulsed alternating electric current electric mode. Results presented here use a laboratory test thruster to create an arc discharge of 5-20 J per pulse in a cylindrical cavity of propellant. Results for Teflon …

Square-Root Consider Filters With Hyperbolic Householder Reflections, James S. Mccabe, Kyle J. De Mars

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Maintaining positive definiteness of a filter's error covariance estimate is of paramount importance to any stable and reliable estimation scheme. Two widely used methods for protecting a filter from loss of positive-definiteness are that of consider filtering and square-root filtering. Despite their widespread use in estimation applications, a filtering methodology that combines the two techniques has yet to be presented in a unified, streamlined architecture. This paper develops a new approach to square-root filtering using hyperbolic Householder reflections. A specialization of the method is considered to permit computationally efficient applications, and a numerical example pertaining to a ballistic reentry is …

Application Of Improved Fast Dynamic Allan Variance For The Characterization Of Mems Gyroscope On Uav, Qian Zhang, Xueyun Wang, Shiqian Wang, Chaoying Pei

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Microelectromechanical systems (MEMS) are core components in unmanned aerial vehicles (UAV). The precision of MEMS sensors is very important when the GPS signal is invalid. However, the precision and performance of MEMS sensors will be degraded by the changing of environment. Therefore, estimation and identification of the various noise terms existing in MEMS sensors are deemed to be necessary. The Allan variance is a common and standard method to analyze MEMS sensors, but it cannot be used to analyze the dynamic characteristics. The dynamic Allan variance (DAVAR) is a sliding version of the Allan variance. It is a practical tool …

Tortuosity Calculations, Blood Flow Simulations, And Mechanical Testing Of Mouse Aortae, Shawn Pavey, Jessica Wagenseil

Undergraduate Research Symposium Posters

Aortic aneurysms can lead to wall rupture or dissection, which are both deadly occurrences. The risk of developing problematic aneurysms increases with age, making them a growing concern in the USA’s aging population. Thoracic Aortic Aneurysm (TAA) treatment is highly effective if the TAA is diagnosed in time, however current surgical guidelines catch less than half of fatal TAA cases. Tortuosity (related to vessel length divided by the straight distance between two points of interest) has been proposed as a supplement to diameter based diagnosis of severity of TAA progression. This study aimed to confirm the validity of that proposal …

Mechanical Annealing Of Model Glasses: Effects Of Strain Amplitude And Temperature, Nikolai V. Priezjev

Mechanical and Materials Engineering Faculty Publications

Molecular dynamics simulations are performed to examine the dynamic response of amorphous solids to oscillatory shear at finite temperatures. The data were collected from a poorly annealed binary glass, which was deformed periodically in the elastic regime during several hundred shear cycles. We found that the characteristic time required to reach a steady state with a minimum potential energy is longer at higher temperatures and larger strain amplitudes. With decreasing strain amplitude, the asymptotic value of the potential energy increases but it remains lower than in quiescent samples. The transient decay of the potential energy correlates well with a gradual …

Design And Experimental Study Of A High Pressure And Supercritical Methane-Oxygen Burner, A S M Arifur Rahim Chowdhury

Open Access Theses & Dissertations

Directly heated supercritical oxy-fuel power cycles have potential to offer a higher thermal efficiency and lower pollutant emissions compared to existing power cycles. Recent thermodynamic analysis of the cycle performed by several groups including the UTEP-Air Liquide research team show that combustion in the vicinity of 300 bar pressure and 1000-1400 K temperature allows for relatively high system efficiencies while operating within the limit of practical combustor materials. However, the realization of directly heated supercritical power cycle requires combustion systems be designed to operate in supercritical conditions and at temperature far below the blowout limit of conventional flames (above 1500 …

Additive Manufacturing Of Multi-Functional Nanocomposites For Sensor And Energy Storage Devices, Hoejin Kim

Open Access Theses & Dissertations

The goal of this research is to develop novel 3D printing process and design nanocomposites for piezoelectric and dielectric devices using fused deposition modeling (FDM) and stereolithography (SL) 3D printing techniques for use in sensor and energy storage applications. Techniques for electric and corona assisted in-situ poling during 3D printing were developed to improve the piezoelectric property and ease of manufacture. Poly(vinylidene fluoride) (PVDF) and barium titanate (BaTiO3, BT) are well-known for their high piezo- and dielectric constants among polymers and ceramics, while multi-walled carbon nanotubes (CNTs) were introduced to improve efficiency of stress reinforcement and conductivity for charge carriers …

Constitutive Model Development For Additive Manufacturing, Diana Berenice Montes

Open Access Theses & Dissertations

Additive manufacturing (AM) is known worldwide for revolutionizing the development of three-dimensional modeling by reducing the time and increasing the precision of parts. For Powder Bed Fusion research is necessary to reduce concerns in residual stress, porosity and cracking in AM parts. A constitutive model was created in Abaqus to validate material properties of 3D printed Al 6061. Finite element analysis was performed to investigate how properties may affect in the modification of parameters to reduce printing imperfections. Research was made as well in polylactic acid properties for material extrusion to explore its behavior for creep and relaxation. Properties were …

Strong Stability Of A Class Of Difference Equations Of Continuous Time And Structured Singular Value Problem, Qian Ma, Keqin Gu, Narges Choubedar

SIUE Faculty Research, Scholarship, and Creative Activity

This article studies the strong stability of scalar difference equations of continuous time in which the delays are sums of a number of independent parameters tau_i, i = 1, 2, . . . ,K. The characteristic quasipolynomial of such an equation is a multilinear function of exp(-tau_i s). It is known that the characteristic quasipolynomial of any difference equation set in the form of one-delayper- scalar-channel (ODPSC) model is also in such a multilinear form. However, it is shown in this article that some multilinear forms of quasipolynomials are not characteristic quasipolynomials of any ODPSC difference equation set. The equivalence …

Strong Stability Of A Class Of Difference Equations Of Continuous Time And Structured Singular Value Problem, Qian Ma, Keqin Gu, Narges Choubedar

SIUE Faculty Research, Scholarship, and Creative Activity

This article studies the strong stability of scalar difference equations of continuous time in which the delays are sums of a number of independent parameters τi, i = 1, 2, . . . , K. The characteristic quasipolynomial of such an equation is a multilinear function of e−τis. It is known that the characteristic quasipolynomial of any difference equation set in the form of one-delay-per-scalar-channel (ODPSC) model is also in such a multilinear form. However, it is shown in this article that some multilinear forms of quasipolynomials are not characteristic quasipolynomials of any ODPSC difference equation set. The equivalence between …

Raman Spectroscopy Of The Skeleton Of The Coral Acropora Cervicornis, Zachary C. Shepard

Honors Undergraduate Theses

Coral reefs are an important element of marine ecosystem that are critical to maintain a healthy environment. Unfortunately, in recent years coral reefs are doing poorly and many in parts of the ocean are simply dying. Therefore, study of coral’s structural response to external loads could answer what will happen with their structures, while they exhibit different types of loading. Therefore, the proposition of using in-situ micro-Raman spectroscopy to study skeletons of Acropora cervicornis was used. Coral skeleton samples I subjected to mechanical loading studied their vibrational properties by exciting the material with 532nm visible light. A uniaxial compressive load …

Optimal Sintering Temperature Of Ceria-Doped Scandia Stabilized Zirconia For Use In Solid Oxide Fuel Cells, Amanda K. Assuncao

Honors Undergraduate Theses

Carbon emissions are known to cause decay of the Ozone layer in addition to creating pollutant, poisonous air. This has become a growing concern among scientists and engineers across the globe; if this issue is not addressed, it is likely that the Earth will suffer catastrophic consequences. One of the main culprits of these harmful carbon emissions is fuel combustion. Between vehicles, power plants, airplanes, and ships, the world consumes an extraordinary amount of oil and fuel which all contributes to the emissions problem. Therefore, it is crucial to develop alternative energy sources that minimize the impact on the environment. …

Mimicking Blood Rheology For More Accurate Modeling In Benchtop Research, Lindsey Webb

Honors Undergraduate Theses

To confirm computer simulations and Computational Fluid Dynamics (CFD) analysis, benchtop experiments are needed with a fluid that mimics blood and its viscoelastic properties. Blood is challenging to use as a working fluid in a laboratory setting because of health and safety concerns. Therefore, a blood analogue is necessary to perform benchtop experiments. Viscosity is an important property of fluids for modeling and experiments. Blood is a shear thinning fluid, so it has a decreasing viscosity with higher shear rates. This project seeks to create a blood mimicking fluid for benchtop laboratory use. Numerous fluids with different combinations of water, …

Ignition Studies Of Oxy-Syngas/Co2 Mixtures Using Shock Tube For Cleaner Combustion Engines, Samuel Barak

Electronic Theses and Dissertations

In this study, syngas combustion was investigated behind reflected shock waves in order to gain insight into the behavior of ignition delay times and effects of the CO2 dilution. Pressure and light emissions time-histories measurements were taken at a 2 cm axial location away from the end wall. High-speed visualization of the experiments from the end wall was also conducted. Oxy-syngas mixtures that were tested in the shock tube were diluted with CO2 fractions ranging from 60% - 85% by volume. A 10% fuel concentration was consistently used throughout the experiments. This study looked at the effects of changing the …

Characterization, Classification, And Genesis Of Seismocardiographic Signals, Amirtaha Taebi

Electronic Theses and Dissertations

Seismocardiographic (SCG) signals are the acoustic and vibration induced by cardiac activity measured non-invasively at the chest surface. These signals may offer a method for diagnosing and monitoring heart function. Successful classification of SCG signals in health and disease depends on accurate signal characterization and feature extraction. In this study, SCG signal features were extracted in the time, frequency, and time-frequency domains. Different methods for estimating time-frequency features of SCG were investigated. Results suggested that the polynomial chirplet transform outperformed wavelet and short time Fourier transforms. Many factors may contribute to increasing intrasubject SCG variability including subject posture and respiratory …

Characterization Of Anisotropic Mechanical Performance Of As-Built Additively Manufactured Metals, Sanna Siddiqui

Electronic Theses and Dissertations

Additive manufacturing (AM) technologies use a 3D Computer Aided Design (CAD) model to develop a component through a deposition and fusion layer process, allowing for rapid design and geometric flexibility of metal components, for use in the aerospace, energy and biomedical industries. Challenges exist with additive manufacturing that limits its replacement of conventional manufacturing techniques, most especially a comprehensive understanding of the anisotropic behavior of these materials and how it is reflected in observed tensile, torsional and fatigue mechanical responses. As such, there is a need to understand how the build orientation of as-built additively manufactured metals, affects mechanical performance …

Adiabatic Film Cooling Effectiveness Of A Transpiration-Cooled Leading Edge Fabricated By Laser Additive Manufacturing, Luisana Calderon

Electronic Theses and Dissertations

Laser additive manufacturing (LAM) is an emerging technology capable of fabricating complex geometries not possibly made by investment casting methods for gas turbine applications. LAM techniques consist of building parts in a layer-by-layer process by selectively melting metal powders. In the present study, a mock leading edge segment of a turbine blade fabricated by LAM of Inconel 718 powders is investigated. For this particular design, the traditional showerhead film cooling holes have been replaced by two strips containing engineered-porous regions with the purpose of simulating the effect of transpiration cooling. Transpiration cooling has been considered a promising external convective cooling …

Hosting Capacity Optimization In Modern Distribution Grids, Mansoor T. Alturki

Electronic Theses and Dissertations

The availability of distributed renewable energy resources and the anticipated increase in new types of loads are changing the way electricity is being produced and supplied to consumers. This shift is moving away from a network delivering power solely from centralized power plants towards a decentralized network which supplements its power production by incorporating local distributed generators (DGs). However, the increased integration of DGs into existing distribution networks is impacting their behavior in terms of voltage profile, reliability, and power quality. To determine the maximum amount of DG that distribution grids can accommodate the concept of hosting capacity is introduced. …

Automated Cfd Optimization To Maximize Wind Farms Performance And Land Use, Rafael Valotta Rodrigues

Electronic Theses and Dissertations

In this research, a computational system was designed to analyze and optimize the layout of wind farms under variable operational conditions. At first, a wind turbine computational fluid dynamic (CFD) model was developed covering the near wake. The near wake flow field was validated against near wake velocity data from the MEXICO experiment. The CFD simulation demonstrated that the tip speed ratio and the pitch angle greatly influence the near wake behavior, affecting the velocity deficit and the turbulence intensity profile in this region. The CFD model was extended to cover the far wake, aiming to become a computational tool …

Lower Back Biomechanics At Non-Chronic Stage Of Low Back Pain, Iman Shojaei

Theses and Dissertations--Biomedical Engineering

Prior studies have reported differences in lower back biomechanics during activities of daily living between individuals with and without chronic low back pain (LBP). Nevertheless, the literature on lower back biomechanics of patients with non-chronic LBP is scant. Therefore, the objective of this study, as the first step towards future prospective studies, was to investigate the lower back biomechanics in patients with non-chronic LBP. Case-control studies were conducted wherein measures of lumbo-pelvic coordination during bending and return tasks as well as measures of mechanical demand on the lower back during lifting tasks in the sagittal plane were investigated between patients …

Assessing The Spatial Accuracy And Precision Of Lidar For Remote Sensing In Agriculture, Surya Saket Dasika

Theses and Dissertations--Biosystems and Agricultural Engineering

The objective of this whole study was to evaluate a LiDAR sensor for high-resolution remote sensing in agriculture. A linear motion system was developed to precisely control the dynamics of LiDAR sensor in effort to remove uncertainty in the LiDAR position/velocity while under motion. A user control interface was developed to operate the system under different velocity profiles and log LiDAR data synchronous to the motion of the system. The LiDAR was then validated using multiple test targets with five different velocity profiles to determine the effect of sensor velocity and height above a target on measurement error. The results …

Pressure-Driven Stabilization Of Capacitive Deionization, Landon S. Caudill

Theses and Dissertations--Mechanical and Aerospace Engineering

The effects of system pressure on the performance stability of flow-through capacitive deionization (CDI) cells was investigated. Initial data showed that the highly porous carbon electrodes possessed air/oxygen in the micropores, and the increased system pressure boosts the gases solubility in saline solution and carries them out of the cell in the effluent. Upon applying a potential difference to the electrodes, capacitive-based ion adsorption occurs in competition with faradaic reactions that consume oxygen. Through the addition of backpressure, the rate of degradation decreases, allowing the cell to maintain its salt adsorption capacity (SAC) longer. The removal of oxygen from the …

Characterization Of The Shape Memory Behavior Of High Strength Nitihfpd Shape Memory Alloys, Guher P. Toker

Theses and Dissertations--Mechanical and Aerospace Engineering

NiTiHf alloys have emerged as potential materials for applications requiring high transformation temperatures (> 100 °C) with high strength and work output. Although they have high transformation temperatures, their low damping capacity, brittleness and poor superelastic responses (of Ti-rich NiTiHf) impedes their wider usage in many industrial applications. In this study, the quaternary alloying element of Pd has been added to NiTiHf alloys to improve and tailor their shape memory behavior,. NiTiHfPd alloys were systematically examined regarding the composition and heat treatments effects.

Effects of substituting Hf with Ti on the shape memory behavior of NiTHfPd alloys were investigated. There …

Regression Analysis Of Factors Impacting Problem Solving Engagement Within Lean Systems Implementation, David M. Parsley Ii

Theses and Dissertations--Mechanical and Aerospace Engineering

Organizations around the world have attempted to implement the concepts of the Toyota Production System (TPS), commonly referred to as Lean, with limited sustainable success. The central principles of TPS, continuous improvement and respect for people, are grounded in the Japanese values of Monozukuri and Hitozukuri. Monozukuri deals with creating or making a product, while Hitozukuri conveys the idea of developing people through learning. In order for organizations to adopt these values they must have a system that engages employees at all levels in applying problem solving to improve their work. This research uses organizational assessments obtained from a variety …

Characterization Of Rotary Bell Atomizers Through Image Analysis Techniques, Jacob E. Wilson

Theses and Dissertations--Mechanical and Aerospace Engineering

Three methods were developed to better understand and characterize the near-field dynamic processes of rotary bell atomization. The methods were developed with the goal of possible integration into industry to identify equipment changes through changes in the primary atomization of the bell. The first technique utilized high-speed imaging to capture qualitative ligament breakup and, in combination with a developed image processing technique and PIV software, was able to gain statistical size and velocity information about both ligaments and droplets in the image data. A second technique, using an Nd:YAG laser with an optical filter, was used to capture size statistics …