Engineering Commons^™

Implementing A Linear Quadratic Spacecraft Attitude Control System, Daniel Kolosa

Masters Theses

This thesis implements a linear quadratic attitude control system for a low-thrust spacecraft. The goal is to maintain spacecraft alignment with a time-varying thrust vector needed for trajectory change maneuvers. A linear quadratic attitude control approach is used to maintain spacecraft pointing throughout flight. This attitude control strategy uses the thrust-acceleration input obtained from a linear quadratic optimal trajectory control model that simulates the trajectory of a spacecraft in orbit maneuvers. This attitude model simulates a CubeSat, a small satellite that is equipped with a low-thrust propulsion and attitude control system. An orbit raising and a plane change scenario is …

Impurity Effects In All-Vanadium Redox Flow Batteries, Andrew William Burch

Masters Theses

In this dissertation, the effects of VOSO₄ [vanadyl sulfate] source and impurities on the beginning-of-life (BOL) performance of an all-vanadium redox flow battery (VRFB) are explored. Battery performance was monitored at 50% state of charge (SOC) using electrolyte with VOSO₄ purities of 99%, 99.9% and 99.99% by weight. At cell potentials of 1.23V, the least pure solution yielded the lowest current density of 280 mA/cm² [square centimeter] and the most pure solution yielded the highest, 560 mA/cm². The voltage efficiencies and charge-discharge capacities were shown to follow the same trends. Scanning electron microscopy (SEM) images …

Evaluation Of Fuel Flow Measurement Uncertainty In A Turbine Engine Test Cell, Paul Andrew Wright

Masters Theses

The evaluation of measurement uncertainty is an essential part of measurement and data analysis. Measurement uncertainty is itself a measure of the “goodness” of the measured data and helps the analyst to make decisions based on the data. In the turbine engine testing world, accurate measurement of fuel flow is critical. Specific fuel consumption is a combination of thrust and fuel flow and is used to calculate the allowable payload and range of an aircraft as well as the cruising speed. Naturally, test customers (engine manufacturers, aircraft designers, and operators) are very sensitive to the accuracy of fuel flow measurement. …

Optimization Of Titanium Liquid/Gas Diffusion Layers In Proton Exchange Membrane Electrolyzer Cells, Stuart Mccoy Steen

Masters Theses

Polymer electrolyte membrane electrolyzer cells (PEMECs), which are reverse PEM fuel cells (PEMFCs), are effective energy storage medium by producing hydrogen/oxygen from water using electricity from renewable energy sources. This is due in part because of its efficiency, high energy density, compact design, and large capacity. In a PEMEC, a liquid/gas diffusion layer (LGDL) is located between the catalyst layer and the current distributing flow field. The LGDL is expected to transport electrons, heat, and reactants/products to and from the catalyst layer with minimum voltage, current, thermal, interfacial, and fluidic losses. Carbon materials (carbon paper or carbon cloth), typically used …

Extending The Lean Limit Of Methane-Air Mixtures By Oxygen, Nitrogen And Carbon Dioxide Injection In The Gap Of The Spark Plug’S Electrodes, Artem Alexandrov Temerev

Masters Theses

An experimental investigation is carried out to investigate the feasibility of extending the lean limit for methane–air mixtures by injecting oxygen and other gases such as nitrogen and carbon dioxide in the area between spark plug electrodes. Additionally, the effect of oxygen injection on exhaust gas recirculation (EGR) is investigated. The pressure in the chamber and the equivalence ratio of the mixture are varied from 0.35 MPa to 1.03 MPa and 0.46 to 1.0, respectively. Delco 12620540 spark plug is used as the ignition source and the gas injection into spark plug gap is accomplished through a 0.159-cm OD stainless …

Towards A Semantic Knowledge Management Framework For Laminated Composites, Vivek Premkumar

Masters Theses

The engineering of laminated composite structures is a complex task for design engineers and manufacturers, requiring significant management of manufacturing process and materials information. Ontologies are becoming increasingly commonplace for semantically representing knowledge in a formal manner that facilitates sharing of rich information between people and applications. Moreover, ontologies can support first-order logic and reasoning by rule engines that enhance automation. To support the engineering of laminated composite structures, this work developed a novel Semantic LAminated Composites Knowledge management System (SLACKS) that is based on a suite of ontologies for laminated composites materials and design for manufacturing (DFM) and their …

A Continous Rotary Actuation Mechanism For A Powered Hip Exoskeleton, Matthew C. Ryder

Masters Theses

This thesis presents a new mechanical design for an exoskeleton actuator to power the sagittal plane motion in the human hip. The device uses a DC motor to drive a Scotch yoke mechanism and series elasticity to take advantage of the cyclic nature of human gait and to reduce the maximum power and control requirements of the exoskeleton. The Scotch yoke actuator creates a position-dependent transmission that varies between 4:1 and infinity, with the peak transmission ratio aligned to the peak torque periods of the human gait cycle. Simulation results show that both the peak and average motor torque can …

Thermodynamic Analysis Of The Application Of Thermal Energy Storage To A Combined Heat And Power Plant, Benjamin Mcdaniel

Masters Theses

The main objective of this paper is to show the economic and environmental benefits that can be attained through the coupling of borehole thermal energy storage (BTES) and combined heat and power (CHP). The subject of this investigation is the University of Massachusetts CHP District Heating System. Energy prices are significantly higher during the winter months due to the limited supply of natural gas. This dearth not only increases operating costs but also emissions, due to the need to burn ultra low sulfur diesel (ULSD). The application of a TES system to a CHP plant allows the plant to deviate …

Loss On Ignition Using Infrared Heating, Benjamin J. Binoniemi

Masters Theses

The focus of this study is a proof of concept that infrared heating can be used to produce a reliable and rapid method of performing the loss on ignition test. The loss on ignition test is a foundry industry standard test that requires all moisture and volatile organic compounds be vaporized from a sample of foundry sand. The standard test as recommended by the American Foundry Society uses a muffle oven and requires nearly four hours to perform. This new concept performs the same test in approximately ten minutes. The biggest issues with the loss on ignition test are time …

Impact Of Solidification On Tensile Strength Of Cocr 2lc In Selective Laser Melting, Stefan Robert Popp

Masters Theses

Selective laser melting (SLM) is an additive manufacturing technique with which parts of nearly arbitrary shape and complexity can be produced. The parts are generated layer for layer directly out of a 3D CAD model completely without forming tools.

In this work, the selective laser technique is applied to a CoCrMo alloy. Due to its high corrosion resistance, wear-resistance, and heat resistance, this alloy is mainly used for medical or high temperature applications.

A systematic approach is used to investigate the influence of the process parameters laser power and exposure time (pulsed laser) on density, melt pool dimensions, melt pool …

Cfd Analysis Of Viscosity Effects On Turbine Flow Meter Performance And Calibration, Carl Tegtmeier

Masters Theses

In this research turbine flow meters were studied, using computational fluid dynamics (CFD) modeling to the study effects of viscosity on the flow meters, across a wide range of operation, to improve our understanding and their performance. A three-dimensional computational model was created for a typical flow meter geometry. The work began with a steady state model to provide an acceptable initial condition for further simulations. These results were input into a transient model that has a rotating zone around the rotor to provide insight into the interaction between static and rotational structures. In order to automatically adjust the rotor …

Phase Dynamics Of Locset Control Methodology, Brendan Neschke

Masters Theses

Single-mode fiber amplifiers produce diffraction-limited beams very efficiently. Maximum beam intensity requires that an array of these amplifiers have their beams coherently combined at the target. Optical path differences and noise adversely affect beam quality. An existing closed loop phase control methodology, called the locking of optical coherence by single-detector electronic-frequency tagging (LOCSET), corrects phase errors in real time by electronically detecting path length differences and sending signals to lithium niobate phase adjusters. Broadening the line-width using “jitter” of the input signal can increase the output power of an individual amplifier by suppressing nonlinearity. The system dynamics of LOCSET are …

On The Dynamic Analysis Of Compliant Mechanisms Based On The Pseudo-Rigid-Body Model, Andrew Christian

Masters Theses

"Compliant mechanisms derive some or all of their mobility from the deflection of flexible members. A pseudo-rigid-body model (PRBM) provides an elegant and simple way of modeling and analyzing traditionally nonlinear large-deflection problems pertaining to compliant mechanisms. In this work, several aspects pertainting to the dynamics of compliant mechanisms are considered. First, dynamic models are derived to predict not only the natural frequency of the large-deflection systems, but also the transient response, using the PRBM approach. A unique multi-stage damping model is developed to determine the transient response in free vibration. Recent works have neglected to consider the transient response …

Thermodynamic And Chemical Kinetic Coupled Modeling For The Determination Of Cyclic Combustion Phasing In Hcci Engines, Krishawn Michele Goodwin

Masters Theses

"Homogeneous charge compression ignition (HCCI) is a low temperature combustion mode that contains great potential for decreasing emissions while increasing efficiency in internal combustion engines. The limitation is in that it is inherently difficult to control based on the lack of an external combustion trigger. This thesis outlines the potential of using the combustion residual species of carbon monoxide as a method of controlling the location of combustion by using data from a computer model. The model is a nonlinear five-state thermodynamic model that is coupled with a skeletal chemical kinetic model for PRF96. The model computes the amount of …

Parameter Determination And Experimental Validation Of A Wire Feed Additive Manufacturing Model, Kannan Suresh Kumar

Masters Theses

“Laser metal deposition is an additive manufacturing method with great scope and robustness. The wire fed additive manufacturing method has great opportunities in space applications and other zero gravity manufacturing processes. Process parameters play an important role in controlling the complex phenomenon and obtaining an ideal manufactured part. These parameters can be efficiently determined using simulation tools which are highly essential in visualizing real world experiments, therefore saving time and experimental costs. The objective of this study is to develop a transient 3D model of laser aided wire feed metal deposition which realizes the heat transfer and fluid flow behavior …

Estimation Of Tip-Sample Force In Tapping Mode Atomic Force Microscopy Using Neural-Network And Repetitive Control Approaches, Alireza Toghraee

Masters Theses

"Atomic Force Microscopy is one of the most powerful tools for imaging, measuring and manipulating materials at nanometer scale. Among different modes of AFM, tapping mode, in which the oscillating tip touches the sample periodically, is most common mode. During the tip approach and retract, the tip interacts with sample and experiences different force regimes. This tip-sample interaction force contains information about the sample topology, material properties and tip geometry. However, quantitative measurement of the time-varying tip-sample interaction forcing function is challenging in the tapping mode because of the combined dynamic complexities of the cantilever and nonlinear complexity of the …

Freeze-Form Extrusion Fabrication Of Boron Carbide, Aaron Scott Thornton

Masters Theses

"Boron carbide is a safe, alternative to beryllium as a material for aerospace structures since it is also light-weight and exhibits high strength. This paper discusses a study of the Freeze-form Extrusion Fabrication (FEF) process to fabricate parts from boron carbide. Process parameters and hardware were modified to fabricate boron carbide specimens free of printed defects. Four-point bending tests were performed to measure the flexural strength of fabricated specimens. Observations of the presence of voids caused by ice crystals in fabricated parts led to further development and characterization of the boron carbide paste used with the FEF process. Additives were …

Emission And Energy Analysis Of Self-Sufficient Biomass Power Plant To Achieve Near Net Zero Co₂ Emission, Baburaj Kanagarajan

Masters Theses

"The use of biomass to fuel power plants is considered by many to be a carbon neutral solution to carbon dioxide emissions. One objection to this method of power generation is the gasoline or diesel spent in the transportation and feedstock production, which is a major contributor to carbon emission. In addition, costs associated with the transportation of the biomass fuels are also a major limiting. This work investigates the use of a hybrid farming facility as a means of distributed generation combined. A model that incorporates a small scale biomass power facility located within a farming facility is examined. …

Experimental And Computational Analysis Of Thermosyphon Based Water Heaters, Siddarth Ashokkumar

Masters Theses

"Storage type electric water heaters are one of the most commonly found type of heaters in households today. Due to energy costs and limited generation capacity, there is a need for improving the efficiency of such water heaters. The efficiency of water heating systems have impact both at the household and at the national level, because of their sheer numbers. Efficient water heaters lead to lower utility bills for the consumer and also reduced demand on the grid supplying electrical power to such households. This leads to a reduction in the amount of fuel used in generating electrical power and …

Numerical Study Of Upstream And Downstream Regions Of One Dimensional Detonation Wave In A Dusty Gas Medium, Shubhadeep Banik

Masters Theses

"In detonative combustion very high temperatures are attained by the burned gases. As a result, a large amount of thermal energy is produced during the combustion process. This heat can affect the state of the unburned fuel through radiation of heat from the burned gases. In this study a one-dimensional model was deemed appropriate to gain insight into the fundamental structure of the detonation wave. In this model, the detonation wave divides the fluid stream into an upstream region, consisting of fuel and oxidant, and a downstream region, consisting of burned gases. A set of computer programs, some developed during …

American Sign Language Alphabet Recognition Using Microsoft Kinect, Cao Dong

Masters Theses

"American Sign Language (ASL) fingerspelling recognition using marker-less vision sensors is a challenging task due to the complexity of ASL signs, self-occlusion of the hand, and limited resolution of the sensors. This thesis describes a new method for ASL fingerspelling recognition using a low-cost vision camera, which is Microsoft's Kinect. A segmented hand configuration is first obtained by using a depth contrast feature based per-pixel classification algorithm. Then, a hierarchical mode-finding method is developed and implemented to localize hand joint positions under kinematic constraints. Finally, a Random Decision Forest (RDF) classifier is built to recognize ASL signs according to the …

Pipeline Leak Detection, Marcia Golmohamadi

Masters Theses

"In the present research two techniques are applied for leak detection in pipelines. The first method is a hardware-based technique which uses ultrasonic wave's emission for pipeline inspection. Ultrasonic waves are propagated in the pipe walls and reflected signal from leakage will be used for pipe analysis. Several Pipes with various dimensions and characteristics are modeled by finite element method using ANSYS. Second order longitudinal modes of ultrasonic waves are emitted in their walls. For this purpose, excited frequency is calculated such that it excites the second order longitude mode. In order to investigate the behavior of emitted wave in …

Thermographic Investigation Of Laser Metal Deposition, Sreekar Karnati

Masters Theses

"Laser metal deposition as an additive manufacturing technique has been proven to possess the capability for fabricating complex, intricate geometries and excellent material properties through material deposition. Accurate manufacture of such geometric features would require precise control over the material deposition process. The need of the hour are process monitoring and analyses mechanisms that are crucial in ascertaining the occurrence of the intended actions during deposition while also serving as effective learning tools. The current work involved developing and incorporating an Infra-Red (IR) camera as a process monitoring tool for laser metal deposition. Using the IR camera the thermal dynamics …

An Experimental Study Of Fabrication Temperature Effect On Aqueous Extrusion Freeform Fabrication, Jie Li

Masters Theses

"In order to understand the effect of fabrication temperature, a computer controlled 3-D gantry system was used to extrude aqueous alumina paste using Extrusion Freeform Fabrication. The system includes a temperature control subsystem that allows for fabrication of components below the paste's freezing temperature in the range of -10⁰C to -30⁰C and a hot plate with temperature in the range of 20⁰C to 80⁰C inside a room temperature chamber. Comparisons in terms of relative density, mechanical properties, part accuracy and minimum deposition angle were performed by Extrusion Freeform Fabrication at 40⁰C plate temperature inside a room temperature chamber and at …

Laser Surface And Sub-Surface Repair During Metal Additive Manufacturing, Prudvi Teja Ravi

Masters Theses

"This study examines the use of laser surface treatment to repair surface and subsurface defects. Numerical analysis was performed on laser surface melting using Gaussian heat distribution equations to analyze the depth of the melt pool created by the phenomena. Concurrently, a process map was developed with a planned set of experiments by varying the ranges of laser power and travel speed to determine the dimensions of the melt pool across the gamut. The data generated from both the process studies and the numerical analysis was then used to determine the ideal operating ranges of the process parameters to repair …

Spatial And Temporal Modulation Of Heat Source Using Light Modulator For Advanced Thermography, Arvindvivek Ravichandran

Masters Theses

"Thermography is a Non-Destructive Testing (NDT) method that has found increasing use in industry and research. It has the advantages of being non-contact and be able to interrogate a large surface simultaneously. Active thermography using flash lamps as heat source has been demonstrated for identifying blind holes and delamination in composites. Despite these advancements, active thermographic approach fails to defects like cracks. Under uniform illumination heat flow is predominantly 1D and can easily circumvent a narrow feature. This can be overcome by using a focused light/laser source onto the surface to impose a 3D heat flux. The disadvantage is that …

Experimental And Computational Evaluation Of Water Management And Performance Of A Bio-Inspired Pem Fuel Cell In Comparison To A Conventional Flow Field, Venkatanaga Bhaskar Prakash Saripella

Masters Theses

"Fuel cells are being increasingly used in various stationary and transportation power applications due to their higher energy efficiency and lower pollution. Flow field design in Proton Exchange Membrane (PEM) fuel cells is a major area of research for performance improvement. Bio-inspired flow field designs have significant potential for increased performance by effective distribution of reactants with better water management capabilities. In this study, a bio-inspired flow field design, formulated using Murray's law and mimicking a typical leaf venation pattern, is experimentally and computationally investigated in comparison to a conventional single serpentine design. Experiments are conducted using a special transparent …

Performance Metrics For Powder Feeder Systems In Additive Manufacturing, Venkata Sivaram Bitragunta

Masters Theses

"In blown powder Direct Metal Deposition (DMD) process, parts are built by adding metal powder on the melt pool created by the laser system. At low feed rates powder feeder systems have perturbations. The study focused on relationship between the perturbation frequencies by inherent powder feeder designs and its impact on deposition quality. Performance metric determine the relation between perturbations in the powder flow and quality of the deposit. To determine performance metric, various powder feeder designs were analyzed. Perturbation frequencies were introduced to the disk feeder design. The quality of the deposit was determined by the surface roughness of …

A Force Feedback Haptic Interface For Atomic Force Microscopy, Abdulmohsen Alabdulmuhsin

Masters Theses

"Integrating a force feedback haptic device with atomic force microscopy (AFM) improves the capability to investigate and manipulate the objects on a micro- and nanoscale surface. The haptic device provides the researcher with a sense of touch and movement by changing the position of the stylus or amount of force on it. The developed system's concept is to provide the user a sense and feel and control of the AFM probe at the nanoscale. By positing the haptic stylus, the user generates reference to commands to the AFM probe. In turn, forces experienced by the probe are communicated to the …

On The Design Of A Nearly Constant-Force Modular Device Based On A Compliant Slider Mechanism, Krutika Karthik

Masters Theses

"Compliant mechanisms derive some or all of their mobility from the deflection of their flexible members. A pseudo-rigid-body model (PRBM) provides a simple and efficient way of modeling and analyzing large deflections in compliant mechanisms. In this work, a partially compliant slider mechanism, composed of rigid and compliant segments as well as rigid-body revolute and prismatic pairs, is considered. In recent works, such mechanisms have been dimensionally synthesized to produce substantially constant-force output over a finite range of input link displacement in an in-line PRBM of a compliant slider mechanism. In this thesis, the current practice of using partially compliant …