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Articles 1 - 30 of 77
Full-Text Articles in Engineering
A Study Of The Effect Of Preparation Parameters On The Mechanical Properties Of Freeze-Dried Gelatin-Elastin-Hyaluronate Scaffolds, Mansour Qamash
A Study Of The Effect Of Preparation Parameters On The Mechanical Properties Of Freeze-Dried Gelatin-Elastin-Hyaluronate Scaffolds, Mansour Qamash
Master's Theses (2009 -)
This thesis is dedicated to a detailed study of changes in the properties of Gelatin-Elastin-Hyaluronate (GEH) tissue engineering scaffold resulting from changes in preparation parameters. More specifically, utilizing a combination of foaming and freeze-drying techniques, this research investigates the effects of different parameters, including agitation speed, duration time, and chilling temperature on the scaffold’s structural integrity, porosity, and mechanical properties. The methodology involves a carefully calibrated process in which the scaffold matrix is initially prepared by incorporating 8% gelatin, 2% elastin, and 0.5% hyaluronate (w/v) into a homogenous aqueous solution, followed by controlled agitation and subsequent freezing at designated temperatures. …
Investigating The Impacts Of Bin Variability On Particle Size Distributions In Multiphase Eulerian-Eulerian Simulations, Wilbert Alexander Cruz
Investigating The Impacts Of Bin Variability On Particle Size Distributions In Multiphase Eulerian-Eulerian Simulations, Wilbert Alexander Cruz
Master's Theses (2009 -)
In this study, a 3D steady-state Eulerian-Eulerian simulation was developed to investigate flow performance in a dilute pneumatic conveying system. The investigation focused on two main objectives: (1) assessing the influence of bin selection on solution accuracy for representing the polydisperse mixture, and (2) exploring methods to simplify the modeling of polydisperse particles in the simulation by utilizing a mean diameter derived from the mixture’s particle size distribution. The system's geometry and initial boundary conditions featured a 10.6 m long, 150 mm diameter horizontal pipe with both gaseous and solid phases initially moving at 27 m/s . The steady-state simulation …
Shock Compaction Of Graphene Doped Yttria Stabilized Zirconia: An Experimental And Computational Study, Christopher Rueben Johnson
Shock Compaction Of Graphene Doped Yttria Stabilized Zirconia: An Experimental And Computational Study, Christopher Rueben Johnson
Master's Theses (2009 -)
Yttria stabilized zirconia (YSZ) is a broadly used ceramic due to its impeccable hardness and thermal stability. Limitations of the material, however, subsist within its fracture toughness. Literature indicates that shock consolidation may enable production of composite YSZ and graphene mixtures with improved fracture toughness and other material properties while maintaining the material’s nanostructure dimensionality. Therefore, investigation of the compaction phenomena at non-equilibrium states will provide informative results to be used in the fabrication of bulk graphene-YSZ composites. Computational molecular dynamics (MD) simulations and impact experiments are conducted to explore and characterize the dynamic response of the YSZ variants. Molecular …
High Fidelity Dynamic Modeling And Nonlinear Control Of Fluidic Artificial Muscles, Jonathon Earl Slightam
High Fidelity Dynamic Modeling And Nonlinear Control Of Fluidic Artificial Muscles, Jonathon Earl Slightam
Dissertations (1934 -)
A fluidic artificial muscle is a type of soft actuator. Soft actuators transmit power with elastic or hyper-elastic bladders that are deformed with a pressurized fluid. In a fluidic artificial muscle a rubber tube is encompassed by a helical fiber braid with caps on both ends. One of the end caps has an orifice, allowing the control of fluid flow in and out of the device. As the actuator is pressurized, the rubber tube expands radially and is constrained by the helical fiber braid. This constraint results in a contractile motion similar to that of biological muscles. Although artificial muscles …
Control Design And Implementation Of An Active Transtibial Prosthesis, Joseph Klein
Control Design And Implementation Of An Active Transtibial Prosthesis, Joseph Klein
Master's Theses (2009 -)
Prior work at Marquette University developed the Marquette Prosthesis, an active transtibial prosthesis that utilized a torsional spring and a four-bar mechanism. The controls for the Marquette Prosthesis implemented a finite state control algorithm to determine the state of gait of the amputee along with two lower level controllers, a PI moment controller to control the moment during stance and a PID position controller to control the position during stance. The Marquette Prosthesis was successful in mimicking the gait profile presented by Winter. However, after completing human subject testing, the Marquette Prosthesis was insufficient in trying to match the gait …
Computational Methods For Modeling Multicomponent Droplet Vaporization, Alanna Y. Cooney
Computational Methods For Modeling Multicomponent Droplet Vaporization, Alanna Y. Cooney
Master's Theses (2009 -)
Computational fluid dynamics (CFD) models for combustion of multicomponent hydrocarbon fuels must often prioritize computational efficiency over model complexity, leading to oversimplifying assumptions in the sub-models for droplet vaporization and chemical kinetics. Therefore, a computationally efficient hybrid droplet vaporization-chemical surrogate approach has been developed which emulates both the physical and chemical properties of a multicomponent fuel. For the droplet vaporization/physical portion of the hybrid, a new solution method is presented called the Coupled Algebraic-Direct Quadrature Method of Moments (CA-DQMoM) with delumping which accurately solves for the evolution of every discrete species in a vaporizing multicomponent fuel droplet with the computational …
The Effects Of A Reduced Force Aerial Bucket Control On Upper Extremity Muscular Demands As Assessed With Surface Electromyography, Casey D. Garces
The Effects Of A Reduced Force Aerial Bucket Control On Upper Extremity Muscular Demands As Assessed With Surface Electromyography, Casey D. Garces
Master's Theses (2009 -)
A common control for operating aerial bucket trucks for utility companies in North America is called a pistol grip control. Based upon many anecdotal reports of forearm muscle fatigue from workers using this control, Prof. Richard Marklin began an EPRI-sponsored study in 2016 using EMG to determine muscle fatigue of workers while they used the pistol grip. Muscle activity recorded by EMG is a measure of the magnitude of muscle force under controlled conditions. This study confirmed the reports of muscle fatigue in extensor digitorum communis (EDC) muscle in the right forearm. The next phase of the study was to …
Performance Analysis Of Constant Speed Local Abstacle Avoidance Controller Using A Mpc Algorithym On Granular Terrain, Nicholas Haraus
Performance Analysis Of Constant Speed Local Abstacle Avoidance Controller Using A Mpc Algorithym On Granular Terrain, Nicholas Haraus
Master's Theses (2009 -)
A Model Predictive Control (MPC) LIDAR-based constant speed local obstacle avoidance algorithm has been implemented on rigid terrain and granular terrain in Chrono to examine the robustness of this control method. Provided LIDAR data as well as a target location, a vehicle can route itself around obstacles as it encounters them and arrive at an end goal via an optimal route. This research is one important step towards eventual implementation of autonomous vehicles capable of navigating on all terrains. Using Chrono, a multibody physics API, this controller has been tested on a complex multibody physics HMMWV model representing the plant …
Construction And Characterization Of A Single Stage Dual Diaphragm Gas Gun, Nathaniel Steven Helminiak
Construction And Characterization Of A Single Stage Dual Diaphragm Gas Gun, Nathaniel Steven Helminiak
Master's Theses (2009 -)
In the interest of studying the propagation of shock waves, this work sets out to design, construct, and characterize a pneumatic accelerator that performs high-velocity flyer plate impact tests. A single stage gas gun with a dual diaphragm breach allows for a non-volatile, reliable experimental testing platform for shock phenomena. This remotely operated gas gun utilizes compressed nitrogen to launch projectiles down a 14 foot long, 2 inch diameter bore barrel, which subsequently impacts a target material of interest. A dual diaphragm firing mechanism allows the 4.5 liter breech to reach a total pressure differential of 10ksi before accelerating projectiles …
Design Of A Passive Ankle Prosthesis With Energy Return That Increases With Increasing Walking Velocity, Alexander J. Folz
Design Of A Passive Ankle Prosthesis With Energy Return That Increases With Increasing Walking Velocity, Alexander J. Folz
Master's Theses (2009 -)
Patients who undergo a transtibial (below the knee) amputation are often met with a difficult decision: selection of a prosthesis. Limitations of currently available prostheses motivate work on a new solution, the EaSY Walk, a passive device that mimics two key aspects of the natural ankle: non-linear rotational stiffness through implementation of a stiffening flexure mechanism and rotational work output that varies as a function of walking velocity to propel the user forward. To achieve the latter, a strategy to convert the maximum available translational energy acquired from deflection along the leg into rotational energy about the ankle joint through …
Hip Joint Function In People With Femoroacetabular Impingement Syndrome, Philip Malloy
Hip Joint Function In People With Femoroacetabular Impingement Syndrome, Philip Malloy
Dissertations (1934 -)
Femoroacetabular impingement syndrome (FAIS) is a clinical hip disorder that represents symptomatic contact between the proximal femur and rim of the acetabulum during normal hip range of motion. FAIS has been described as a precursor to hip joint osteoarthritis (OA), and results in physical impairments and functional limitations in young individuals and active adults. Despite tremendous growth in arthroscopic hip surgery for FAIS, little is known about how this disorder affects dynamic hip joint function. The purpose of this dissertation was to investigate hip joint function, during clinical and functional activities, both before and after arthroscopic hip surgery for FAIS. …
An Analysis Of Testing Variables In Rapid Compression Machine Experiments, Jenna Ezzell
An Analysis Of Testing Variables In Rapid Compression Machine Experiments, Jenna Ezzell
Master's Theses (2009 -)
There have been discrepancies noted with regards to experimental data from rapid compression machines (RCM). When data is compared from different RCM facilities, the ignition delay times are inconsistent when inspecting any particular temperature. Currently in publications, if these datasets are compared, the discrepancy is said to be due to heat loss, however this issue has yet to be examined more thoroughly. To determine what the root cause of this discrepancy is, four different fake RCM facilities were created and simulated. There were also different sets of initial conditions used to determine how this may affect the data. They were …
Development Of An Optimal Controller And Validation Test Stand For Fuel Efficient Engine Operation, Jack G. Rehn Iii
Development Of An Optimal Controller And Validation Test Stand For Fuel Efficient Engine Operation, Jack G. Rehn Iii
Master's Theses (2009 -)
There are numerous motivations for improvements in automotive fuel efficiency. As concerns over the environment grow at a rate unmatched by hybrid and electric automotive technologies, the need for reductions in fuel consumed by current road vehicles has never been more present. Studies have shown that a major cause of poor fuel consumption in automobiles is improper driving behavior, which cannot be mitigated by purely technological means. The emergence of autonomous driving technologies has provided an opportunity to alleviate this inefficiency by removing the necessity of a driver. Before autonomous technology can be relied upon to reduce gasoline consumption on …
Pore Resolved Simulations Of Char Particle Gasification, Greg Hingwah Fong
Pore Resolved Simulations Of Char Particle Gasification, Greg Hingwah Fong
Master's Theses (2009 -)
Coal is a significant source of energy in today’s world and many studies have been conducted in order to better understand and optimize its use. To address greenhouse effects associated with coal combustion, cleaner methods for harnessing its energy are being explored. One such method is gasification, a process which converts coal into syngas, a mixture consisting primarily of H2 and CO. Syngas can be used to generate electricity or to produce hydrocarbons that can be used as fuels. To better understand and optimize the process, simulations can be used to study the gasification of individual porous char particles that …
X-Ray Tube Anode Balance Analysis And Vacuum Balancer Parameter Optimization, Matthew Malak
X-Ray Tube Anode Balance Analysis And Vacuum Balancer Parameter Optimization, Matthew Malak
Master's Theses (2009 -)
A manufacturing facility is introducing the company's first straddle mount liquid metal spiral groove bearing (SGB) on a rotating anode x-ray tube. In a manufacturing environment, it is critical that processes are robust and timely to drive down costs while also responding to market demand for improvement. There is currently a lot of variation in the anode balance process. Furthermore, there are repeatability questions surrounding the new balancing system that is used in this anode balance process. To better understand the characteristics of the new liquid metal SGB anode and the effects of measurement system variation, the measurement system will …
A Parametric Investigation And Optimization Of A Cylindrical Explosive Charge, Logan Ellsworth Beaver
A Parametric Investigation And Optimization Of A Cylindrical Explosive Charge, Logan Ellsworth Beaver
Master's Theses (2009 -)
Explosive device design has a wide impact in the space, manufacturing, military, and mining industries. As a step toward computer assisted design of explosives, an optimization framework was developed using the Design Analysis Kit for Optimization and Terrascale Applications (Dakota). This software was coupled with the hydrocode CTH. This framework was applied to three exploding cylinder models, two in 1D and one in 2D. Gradient descent, dividing rectangles, and a genetic algorithm were each applied to the one-dimensional models. Parametric studies were performed as a basis for comparison with the optimization algorithms, as well as qualifying the 1D model's accuracy. …
Adaptive Control Of Joystick Steering In Recreational Boats, John Bayless
Adaptive Control Of Joystick Steering In Recreational Boats, John Bayless
Master's Theses (2009 -)
This thesis addresses the challenge of commissioning recreational boats with joystick control when the boat’s physical parameters are not known. The research was conducted by following a model-based, systems engineering approach which leveraged MATLAB simulations and scale-model physical testing. The outcome of the research is a working methodology using L1 Adaptive Control which provides fast adaption in a way that could reduce the cost of commissioning recreational boats with joystick control, improve the robustness of the final design, and potentially expand the accessible market to new boat types.
Characterization Of The Shock Wave Structure In Water, Emilie Teitz
Characterization Of The Shock Wave Structure In Water, Emilie Teitz
Master's Theses (2009 -)
The scientific community is interested in furthering the understanding of shock wave structures in water, given its implications in a wide range of applications; from researching how shock waves penetrate unwanted body tissues to studying how humans respond to blast waves. Shock wave research on water has existed for over five decades. Previous studies have investigated the shock response of water at pressures ranging from 1 to 70 GPa using flyer plate experiments. This report differs from previously published experiments in that the water was loaded to shock pressures ranging from 0.36 to 0.70 GPa. The experiment also utilized tap …
Modeling Pyrolysis Of Large Coal Particles With Many Species, Jianqing Li
Modeling Pyrolysis Of Large Coal Particles With Many Species, Jianqing Li
Master's Theses (2009 -)
Coal currently supplies 40% of the world’s electricity needs, and is one of the most important energy sources. As the initial stage of coal combustion, pyrolysis is a thermal decomposition process which converts coal into light gases and tars, which are subsequently consumed in combustion reactions, as well as solid char. Recently there has been interest in using slow pyrolysis as a stand-alone process for the production of chemicals and fuels from large (mm-scale) coal particles. Simulations can be used to efficiently study the impact of pyrolysis conditions on gas, tar and char yields, as well as gas and tar …
Analysis Of Fatigue Crack Propagation In Welded Steels, Roberto Angelo Demarte
Analysis Of Fatigue Crack Propagation In Welded Steels, Roberto Angelo Demarte
Master's Theses (2009 -)
This thesis presents the study of fatigue crack propagation in a low carbon steel (ASTM A36) and two different weld metals (AWS A5.18 and AWS A5.28). Fatigue crack propagation data for each weld wire is of interest because of its use for predicting and analyzing service failures. Fatigue crack growth test specimens were developed and fabricated for the low carbon steel base metal and for each weld wire. Weld specimens were stress relieved prior to fatigue testing. Specimens were tested on a closed-loop servo hydraulic test machine at two different load ratios. Fatigue test data was collected to characterize both …
Analysis And Synthesis Of A Planar Reconfigurable Mechanism With A Variable Joint, Peter William Malak
Analysis And Synthesis Of A Planar Reconfigurable Mechanism With A Variable Joint, Peter William Malak
Master's Theses (2009 -)
Currently, there is a demand for mechanisms with variable topology that can perform multiple tasks with the least amount of actuators. These devices have the ability to provide numerous motion profiles within one device. In the following thesis, a specific planar reconfigurable mechanism with a kinematic reconfigurable joint was mathematically modeled. This mechanism functions as a RRRP mechanism in one configuration and as a RRRR in the other and is known as a RRRR-RRRP Mechanism. The kinematics and kinetics of the RRRR-RRRP Mechanism were analyzed with a Lagrangian approach. The models are simulated and verified using a trajectory planner and …
Analytical Modeling Of A Novel Microdisk Resonator For Liquid-Phase Sensing: An All-Shear Interaction Device (Asid), Mohamad Sadegh Sotoudegan
Analytical Modeling Of A Novel Microdisk Resonator For Liquid-Phase Sensing: An All-Shear Interaction Device (Asid), Mohamad Sadegh Sotoudegan
Dissertations (1934 -)
Extensive research on micro/nanomechanical resonators has been performed recently due to their potential to serve as ultra-sensitive devices in chemical/biosensing. These applications often necessitate liquid-phase sensing, introducing significant fluid-induced inertia and energy dissipation that reduces the resonator’s performance. To minimize the detrimental fluid effects on such devices, a novel microdisk resonator supported by two tangentially-oriented, axially-driven “legs” is investigated analytically and effects of the system parameters on the resonator/sensor performance are explored. Since the device surface vibrates primarily parallel to the fluid-structure interface, it is referred to here as an “all-shear interaction device,” or ASID. Analytical modeling of the ASID …
Application Of A Multi-Zone Model For The Prediction Of Species Concentrations In Rapid Compression Machine Experiments, David Wilson
Application Of A Multi-Zone Model For The Prediction Of Species Concentrations In Rapid Compression Machine Experiments, David Wilson
Master's Theses (2009 -)
Accurate chemical kinetic models, which predict species evolution and heat release rates in chemically reactive systems, are essential for further advancements in fuel and combustion technology. An experimental facility that is widely used for evaluating the accuracy of kinetic models is a rapid compression machine (RCM), which creates a well-defined reaction environment by compressing a reactive mixture inside a chamber. Generally, RCM experiments are conducted in order to obtain ignition delay data. However, chemical speciation data provides greater insight into reaction pathways, and is therefore a more rigorous benchmark for validating kinetic models. In order for a chemical kinetic model …
Ramifications Of Projectile Velocity On The Ballistic Dart Penetration Of Sand, Peter Anthony Sable
Ramifications Of Projectile Velocity On The Ballistic Dart Penetration Of Sand, Peter Anthony Sable
Master's Theses (2009 -)
With the advent of novel in-situ experimental measurement techniques, highly resolved quantitative observations of dynamic events within granular media can now be made. In particular, high speed imagery and digital analysis now allow for the ballistic behaviors of sand to be examined not only across a range of event velocities but across multiple length scales. In an attempt to further understand the dynamic behavior of granular media, these new experimental developments were implemented utilizing high speed photography coupled with piezo-electric stress gauges to observe visually accessible ballistic events of a dart penetrating Ottawa sand. Projectile velocities ranged from 100 to …
Modeling And Investigation Of Refrigeration System Performance With Two-Phase Fluid Injection In A Scroll Compressor, Rui Gu
Master's Theses (2009 -)
Vapor compression cycles are widely used in heating, refrigerating and air-conditioning. A slight performance improvement in the components of a vapor compression cycle, such as the compressor, can play a significant role in saving energy use. However, the complexity and cost of these improvements can block their application in the market. Modifying the conventional cycle configuration can offer a less complex and less costly alternative approach. Economizing is a common modification for improving the performance of the refrigeration cycle, resulting in decreasing the work required to compress the gas per unit mass. Traditionally, economizing requires multi-stage compressors, the cost of …
Optimizing A Hammer Forging Progression For A Large Hand Tool, Edgar Espinoza
Optimizing A Hammer Forging Progression For A Large Hand Tool, Edgar Espinoza
Master's Theses (2009 -)
In the forging industry of today the need for United States based companies to reduce cost and maintain or improve the quality of a product has become essential in order to remain competitive. A company such as Green Bay Drop Forge (GBDF), a manufacturer of standard and custom steel forgings, was tasked with improving the forging process of one of their large hand tool products. A large wrench, forged at GBDF was noticed to contain a large amount of flash and excessive amount of hammer blows required to forge the part. The large amounts of flash and excessive hammer blows …
Investigation Of Surface Topography Effects On Metal Flow Under Lubricated Hot Compression Of Aluminum, Justin Irvin Kurk
Investigation Of Surface Topography Effects On Metal Flow Under Lubricated Hot Compression Of Aluminum, Justin Irvin Kurk
Master's Theses (2009 -)
An investigation was conducted to study the effects of die surface topography, specifically surface roughness and lay, on metal flow and the friction factor under lubricated hot compression. 6061-T6 aluminum rings and square bar stock specimens were compressed on H-13 tool steel platens machined with a unidirectional lay pattern to six different roughnesses between a R 10 and 240 μin. A lab based hydraulic press mounted with an experimental die set was used for all testing. Repeated trials were conducted using high temperature vegetable oil and boron nitride lubricants. Metal flow was quantified as a function of surface roughness, lay …
Health Condition Monitoring And Fault-Tolerant Operation Of Adjustable Speed Drives, Jiangbiao He
Health Condition Monitoring And Fault-Tolerant Operation Of Adjustable Speed Drives, Jiangbiao He
Dissertations (1934 -)
Adjustable speed drives (ASDs) have been extensively used in industrial applications over the past few decades because of their benefits of energy saving and control flexibilities. However, the wider penetration of ASD systems into industrial applications is hindered by the lack of health monitoring and fault-tolerant operation techniques, especially in safety-critical applications. In this dissertation, a comprehensive portfolio of health condition monitoring and fault-tolerant operation strategies is developed and implemented for multilevel neutral-point-clamped (NPC) power converters in ASDs. Simulations and experiments show that these techniques can improve power cycling lifetime of power transistors, on-line diagnosis of switch faults, and fault-tolerant …
Solid Lubrication Bearing Design Through Analytical And Empirical Vibration Analysis Of Characteristic Frequencies, Christopher A. Schultz
Solid Lubrication Bearing Design Through Analytical And Empirical Vibration Analysis Of Characteristic Frequencies, Christopher A. Schultz
Master's Theses (2009 -)
Ball bearings with solid lubrication lack the damping mechanisms of oil and produce well-defined vibration characteristics based upon given geometry and speed of operation. This work takes advantage of the high signal to noise ratio in x-ray bearings and develops an algorithm to statistically track bearing performance based upon fundamental bearing theory, Monte Carlo simulation, Order Analysis, and Weibull statistics. The technique gathers vibration data solely related to the theoretical operation of a bearing, negates the background noise, and provides descriptive vibration amplitude statistics of individual bearing components for evaluation. The practical implications of the thesis described herein allow the …
Verification Of A Dual-State Extended Kalman Filter With Lidar-Enabled Autonomous Hazard-Detection For Planetary Landers, Peter Joseph Jorgensen
Verification Of A Dual-State Extended Kalman Filter With Lidar-Enabled Autonomous Hazard-Detection For Planetary Landers, Peter Joseph Jorgensen
Master's Theses (2009 -)
This thesis presents a mathematical model for a LIDAR-enabled Terrain- and Hazard-Relative Navigation sensor and the design and implementation of a dual-state extended Kalman filter. The extended Kalman filter equations are presented in summary. Mathematical models for an altimeter, a velocimeter, a star tracker, and a lidar-enabled mapping/tracking sensor are presented in depth. An explanation of the software designed for computer simulation is included. It is proved through this analysis that, when implemented as part of a well-tuned extended Kalman Filter and in combination with other sensors, the proposed model for a lidar-enabled mapping/tracking sensor significantly reduces estimation error. This …