Mechanical Engineering Commons^™

Visual Literacy And The Integration Of Parametric Modeling In The Problem-Based Curriculum, Matthew Benedict Assenmacher

Master's Theses and Doctoral Dissertations

This quasi-experimental study investigated the application of visual literacy skills in the form of parametric modeling software in relation to traditional forms of sketching. The study included two groups of high school technical design students. The control and experimental groups involved in the study consisted of two randomly selected groups of students. The participants were exposed to eight weeks of technical drawing and parametric modeling instruction prior to the start of the study.

The potential applications of emerging technologies for the purpose of integrating visual literacy into the curriculum are not fully understood. Society is moving towards a more immediate …

Development Of An In Situ Measurement Device For Obtaining Material Thermal Properties, Mark A. Hepokoski

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

This thesis presents a methodology for measuring thermal properties in situ, with a special focus on obtaining properties of layered stack-ups commonly used in armored vehicle components. The technique involves attaching a thermal source to the surface of a component, measuring the heat flux transferred between the source and the component, and measuring the surface temperature response. The material properties of the component can subsequently be determined from measurement of the transient heat flux and temperature response at the surface alone. Experiments involving multilayered specimens show that the surface temperature response to a sinusoidal heat flux forcing function is also …

Multi-Physicochemical Modeling Of Solid Oxide Fuel Cells And Electrolyzer Cells, Yuanyuan Xie

Theses and Dissertations

Multi-physicochemical models are developed for solid oxide fuel cells and electrolysis cells. The models describe the complicated transport processes of charge (electron/ion) conservation, mass/species conservation, momentum conservation, and energy conservation. Transport processes are coherently coupled with chemical reforming processes, surface elementary reaction processes, as well as electro-oxidation processes of both hydrogen and carbon monoxide. The models are validated with experimental data and utilized for fundamental mechanism studies of SOFCs fueled with different type of fuels, such as hydrogen, hydrocarbon, e.g., methane, H2S, and their mixtures. The fundamental mechanisms associated with syngas generation using electrolysis cell are also extensively investigated using …

Towards A Fluid Solid Interaction Model Of A Dynamic Lung, Justin C. Jacobs

Electronic Theses and Dissertations

Because the pulmonary system is a site for both environmental particulate contamination, as well as drug delivery into the body, numerous research groups have focused on precisely understanding its inner-workings. Past research has demonstrated the need to realistically model the lung walls in order to accurately capture the complex airflow profile throughout all of the branches. Since this is paramount to properly replicating particulate transport in the lung, computational fluid dynamics simulations on their own are inadequate, as they cannot account for lung wall dilation. Only by coupling the fluid and solid domains can natural lung behavior can be effectively …

2d Modeling Of Forcespinning™ Nanofiber Formation With Experimental Study And Validation, Simon Padron

Theses and Dissertations - UTB/UTPA

A newly developed method of producing nanofibers, called Forcespinning™, has proven to be a viable alternative to mass produce nanofibers. Forcespinning™ utilizes centrifugal forces which allow for a host of new materials to be processed into nanofibers while also providing a significant increase in yield and ease of production. To improve and enhance the Forcespinning™ production method, a 2D computational Forcespinning™ fluid dynamics model is developed. Three computer models, namely time-independent and time-dependent inviscid models and a viscous model are obtained and the influences of various parameters on Forcespinning™ fiber formation are obtained. This work also presents a detailed explanation …

Remanufacturing Cleaning Process Evaluation, Comparison And Planning, Ozan Yagar

Theses and Dissertations - UTB/UTPA

This thesis aims to combine previous research on remanufacturing cleaning processes and applications into a single decision-making tool, in the form of software, which a remanufacturer can use to find a cleaning system that matches their specific demands. This thesis will provide an in-depth review of each cleaning process, the chemicals used in those processes, and the contamination types for which they were developed. This research also provides evaluation and comparison that assists remanufacturers in designing their cleaning systems. Finally, there will be a description and demonstration of the software. The ultimate goal is to find correct cleaning process to …

Modeling Of A New Structure Of Precision Air Conditioning System Using Secondary Condenser For Rh Regulation, Aries Subiantoro, Nasruddin Nasruddin, Feri Yusivar, Muhammad Idrus Al-Hamid, Bagio Budiardjo

Makara Journal of Technology

A dynamic mathematical model for a new structure of precision air conditioning (PAC) has been developed. The proposed PAC uses an additional secondary condenser for relative humidity regulation compared to a basic refrigeration system. The work mechanism for this system and a vapour-compression cycle process of the system are illustrated using psychrometric chart and pressure-enthalpy diagram. A non-linear system model is derived based on the conservation of mass and energy balance principles and then linearized at steady state operating point for developing a 8th-order state space model suited for multivariable controller design. The quality of linearized model is analyzed in …

Dynamic Characterization Of Vocal Fold Virbrations, Zhenyi Wei

LSU Doctoral Dissertations

An emerging trend among voice specialists is the use of quantitative protocols for the diagnosis and treatment of voice disorders. Vocal fold vibrations are directly related to voice quality. This research is devoted to providing an objective means of characterizing these vibrations. Our goal is to develop a dynamic model of vocal fold vibration, and map the parameter space of the model to a class of voice disorders; thus, furthering the assessment and diagnosis of voice disorder in clinical settings.

To this end, this dissertation introduces a new seven-mass biomechanical model for the vibration of vocal folds. The model is …

Transport Phenomena Associated With Liquid Metal Flow Over Topographically Modified Surfaces, Wen Liu

Theses and Dissertations--Mechanical and Aerospace Engineering

Brazing and soldering, as advanced manufacturing processes, are of significant importance to industrial applications. It is widely accepted that joining by brazing or soldering is possible if a liquid metal wets the solids to be joined. Wetting, hence spreading and capillary action of liquid metal (often called filler) is of significant importance. Good wetting is required to distribute liquid metal over/between the substrate materials for a successful bonding.

Topographically altered surfaces have been used to exploit novel wetting phenomena and associated capillary actions, such as imbibitions (a penetration of a liquid front over/through a rough, patterned surface). Modification of surface …

Design Of Contact Line Friction Measurement Machine Apparatus, Seyed Kamran Najafi

USF Tampa Graduate Theses and Dissertations

The purpose of this project is to design and manufacture a high precision machine to directly measure the surface force of fluids. Knowing how to move droplets easier with less resistance can increase the potential of a wide range of applications and improve the performance of things such as self-assembly applications. This machine has the ability to measure forces of up to 100 N with a MEMS based sensor. The motion system on this machine moves a substrate underneath of a droplet for 100 mm and applies dragging force to the sensor. It moves with a controlled speed with high …

Development Of A Structured Concrete Thermocline Thermal Energy Storage System, Bradley M. Brown

Graduate Theses and Dissertations

The past couple of decades have shown a concern when considering the way the world obtains its power. The focus has been switching from fossil fuels that have been used for hundreds of years to renewable energy sources, such as the sun. Solar energy is readily and infinitely available for harnessing. One problem with solar energy, though, is its inability to be used during the night time and during cloud covered weather. A solution to this problem is the use of energy storage mechanisms. For solar plants that use solar thermal energy (concentrating solar power plants), thermal energy storage (TES) …

An Evaluation Of Constitutive Laws And Their Ability To Predict Flow Stress Over Large Variations In Temperature, Strain, And Strain Rate Characteristic Of Friction Stir Welding, Katherine Lynn Kuykendall

Theses and Dissertations

Constitutive laws commonly used to model friction stir welding have been evaluated, both qualitatively and quantitatively, and a new application of a constitutive law which can be extended to materials commonly used in FSW is presented. Existing constitutive laws have been classified as path-dependent or path-independent. Path-independent laws have been further classified according to the physical phenomena they capture: strain hardening, strain rate hardening, and/or thermal softening. Path-dependent laws can track gradients in temperature and strain rate characteristic to friction stir welding; however, path-independent laws cannot. None of the path-independent constitutive laws evaluated has been validated over the full range …

Turbulence Modeling Of Strongly Heated Internal Pipe Flow Using Large Eddy Simulation, Michal Hradisky

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The main objective of this study was to evaluate the performance of three Large Eddy Simulation (LES) subgrid scale (SGS) models on a strongly heated, low Mach number upward gas flow in a vertical pipe with forced convection. The models chosen for this study were the Smagorinsky-Lilly Dynamic model (SLD), the Kinetic Energy Transport model (KET), and the Wall-Adaptive Local-Eddy viscosity model (WALE). The used heating rate was sufficiently large to cause properties to vary significantly in both the radial and streamwise directions. All simulations were carried out using the commercial software FLUENT.

The effect of inlet turbulence generation techniques …

Modeling And Performance Investigation Of A Rotor With Dissimilar Bearing Support System, Yunlu Li

ETD Archive

Different types of bearings have different dynamic characteristics. By using one type of bearing at one end of a rotor and another type of bearing at the other end of the rotor, it is possible to exploit the advantages of both types in the same system. One example of such combination is a bronze bushing and active magnetic bearing (AMB). In the available literature, there are examples of such systems but are not fully explored with regard to how to model the system to fully utilize both support type properties. This thesis investigates the modeling and performance of such a …

Model Identification, Updating, And Validation Of An Active Magnetic Bearing High-Speed Machining Spindle For Precision Machining Operation, Adam C. Wroblewski

ETD Archive

High-Speed Machining (HSM) spindles equipped with Active Magnetic Bearings (AMBs) are envisioned to be capable of autonomous self-identification and performance self-optimization for stable high-speed and high quality machining operation. High-speed machining requires carefully selected parameters for reliable and optimal machining performance. For this reason, the accuracy of the spindle model in terms of physical and dynamic properties is essential to substantiate confidence in its predictive aptitude for subsequent analyses.This dissertation addresses system identification, open-loop model development and updating, and closed-loop model validation. System identification was performed in situ utilizing the existing AMB hardware. A simplified, nominal open-loop rotor model was …

Effects Of Large-Scale Transient Loading And Waste Heat Rejection On A Three Stream Variable Cycle Engine, Michael William Corbett

Browse all Theses and Dissertations

The objective of the research presented in this document was to gain an understanding of the feasibility of extracting large amounts of transient shaft power from a variable cycle engine and to reject waste heat into the third stream bypass duct. This first required the development of a transient engine and controller simulation. After performing basic verification of the model, such as ensuring conservation of mass, tests were run for three missions using a low-efficiency periodic load which both required shaft power and created low quality waste heat. The waste heat generated by that load was lifted by a cooling …

Plant Growth Modeling Using L-System Approach And Its Visualization, Atris Suyantohadi, Alfiyan Alfiyan, Mochamad Hariadi, Mauridhi Hery Purnomo

Makara Journal of Technology

The visualization of plant growth modeling using computer simulation has rarely been conducted with Lindenmayer System (L-System) approach. L-System generally has been used as framework for improving and designing realistic modeling on plant growth. It is one kind of tools for representing plant growth based on grammar sintax and mathematic formulation. This research aimed to design modeling and visualizing plant growth structure generated using L-System. The environment on modeling design used three dimension graphic on standart OpenGL format. The visualization on system design has been developed by some of L-System grammar, and the output graphic on three dimension reflected on …

Optimization And Correlation Of The Penn State Model Of Friction Stir Welding To Experimental Welds In 304l Stainless Steel, Devin Donaldson Furse

Theses and Dissertations

A numerical model of friction stir welding developed by T. DebRoy, R. Nandan, and others has been optimized to fit experimental data of eleven welds of 304L stainless steel at various weld feed rates and spindle speeds. Optimization was used to determine the values of five difficult-to-measure model parameters. The optimal parameter values were then correlated to the weld machine inputs. The mechanical efficiency and the coefficient of friction were not correlated with feed rate, spindle speed, or axial pressure. Tool slip was positively correlated with feed rate, negatively correlated with spindle speed, and not correlated with axial pressure. The …

Mathematical Modeling Of Light Utilization And The Effects Of Temperature Cycles On Productivity In A Steady-State Algal Photobioreactor, Peter Edwin Zemke

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The work presented here investigated two methods of improving productivity in microalgal photobioreactors: applying temperature cycles intended to maximize photosynthesis and minimize respiration, and development of a mathematical model that predicts improvements in photon utilization using temporal light dilution (flashing).

The experiments conducted on diurnal temperature cycles with Dunaliella tertiolecta in 30-L outdoor photobioreactors showed that a properly chosen temperature cycle can improve mass and energy productivity by 18% over an identical photobioreactor with a constant temperature. However, excessively large temperature cycle amplitudes reduced productivity. A 4-7% increase in energy content was observed in microalgae exposed to temperature cycles. The …

Aircraft Gearbox Dynamics Subject To Electromechanical Actuator Regenerative Energy Flow, Matthew S. Rutledge

Browse all Theses and Dissertations

To increase reliability and efficiency, standard aircraft components are being replaced with more electric subsystems aimed to reduce weight, conserve space, and improve energy management. One application of this process replaces standard hydraulic actuators used in flap or aileron movements with electromechanical actuators powered by an external generator. During different types of return movements, the electromechanical actuator will produce regenerative power that flows back through the generator and pulses into the engine-gearbox subsystem. The regenerative power, defined by characteristic amplitude, frequency, and other pulse attributes, coupled with the driving force produced by the engine may dramatically impact the performance and …

Modeling Of The Interior Electric Field In Photovoltaic Cells, Tara Jeatran

The Journal of Undergraduate Research

With the emergence of photovoltaic technologies, there is a strong technological demand for high-performance photovoltaic devices. One of the most promising device concepts developed at SDSU is organic-based photovoltaic cells. The performance of the PV cells is controlled by charge generation and charge separation, and charge transportation processes. Extraordinary control over the properties of the organic photovoltaic materials will be needed in order for this research to succeed. Therefore, the interior electric field and the macro electric properties of the system are the foundation behind these facts and are critical properties on their performance. In this paper, the fundamentals of …

Carbon-Free Compressed Air Energy Storage, Dustin Andrew Shively

Boise State University Theses and Dissertations

The inherent intermittency of the two fastest growing renewable energy sources, wind and solar, presents a significant barrier to widespread penetration and replacement of fossil-fuel sourced baseload generation. These intermittencies range from short term ramp events experienced by wind farms to the diurnal fluctuation of solar installations. Traditionally, grid operators have had very little control over demand and full control over supply. With the increase in wind and solar based generation onto an electric grid comes a decrease in control of supply. Grid operators are required to have a certain amount of spinning reserve ready to respond when wind or …

A Mixed-Dimensionality Modeling Approach For Interaction Of Heterogeneous Steam Reforming Reactions And Heat Transfer, Jeroen Valensa

Master's Theses (2009 -)

Hydrogen is most often produced on an industrial scale by catalytic steam methane reforming, an equilibrium-limited, highly endothermic process requiring the substantial addition of heat at elevated temperatures. The extent of reaction, or conversion efficiency, of this process is known to be heat transfer limited. Scaling the industrial process equipment down to the size required for small, compact fuel cell systems has encountered difficulties due to increased heat losses at smaller scales. One promising approach to effectively scale down the reforming process is to coat the catalyst directly onto the heat exchange surfaces of an integrated reactor/heat exchanger. In this …

Experimental And Numerical Study Of A Proton Exchange Membrane Electrolyzer For Hydrogen Production, Sachin S. Deshmukh

UNLV Theses, Dissertations, Professional Papers, and Capstones

Hydrogen as a fuel source has received attention from researchers globally due to its potential to replace fossil based fuels for energy production. Research is being performed on hydrogen production, storage and utilization methods to make its use economically feasible relative to current energy sources. The PEM electrolyzer is used to produce hydrogen and oxygen using water and electricity. Focus of our study is to provide a benchmark experiment and numerical model of a single cell electrolyzer that can assist in improving the current state of understanding of this system. Parametric analysis of an experimental cell was performed to understand …

A Mechanistic Investigation Of Nitrogen Evolution In Pulverized Coal Oxy-Fuel Combustion, Andrew John Mackrory

Theses and Dissertations

Oxy-fuel combustion is an enabling technology for capture of CO2 from coal combustion, the economics of which depends strongly on the ability of the process to produce low NOX emissions. The literature contains many reports of lower NOX emissions from oxy-fuel combustion but the reasons for this are not fully understood. The objective of this work was to gain understanding of nitrogen evolution under pulverized coal oxy-fuel conditions. Pulverized coal was burned in a once-through, down-fired, laminar flow reactor. Nitrogen compounds and other combustion species were measured at the reactor centerline as a function of distance from the burner. Dry …

Parametric Optimization Design System For A Fluid Domain Assembly, Matthew Jackson Fisher

Theses and Dissertations

Automated solid modeling, integrated with computational fluid dynamics (CFD) and optimization of a 3D jet turbine engine has never been accomplished. This is due mainly to the computational power required, and the lack of associative parametric modeling tools and techniques necessary to adjust and optimize the design. As an example, the fluid domain of a simple household fan with three blades may contain 500,000 elements per blade passage. Therefore, a complete turbine engine that includes many stages, with sets of thirty or more blades each, will have hundreds of millions of elements. The fluid domains associated with each blade creates …

A Model For Predicting The Piezoresistive Effect In Microflexures Experiencing Bending And Tension Loads, Gary K. Johns, Larry L. Howell, Brian D. Jensen, Timothy W. Mclain

Faculty Publications

This paper proposes a model for predicting the piezoresistive effect in microflexures experiencing bending stresses. Linear models have long existed for describing piezoresistivity for members in pure tension and compression. However, extensions of linear models to more complex loading conditions do not match with experimental results. A second-order model to predict piezoresistive effects in tension, compression, and more complex loading conditions is proposed. A reduced form of the general second-order model is presented for thin flexures in bending. A three-step approach is used to determine the piezoresistive coefficients for this reduced-form model. The approach is demonstrated for two sets of …

One-Dimensional Radial Flow Turbomachinery Performance Modeling, Robert John Pelton

Theses and Dissertations

The Two-Element In Series (TEIS) and Two-Zone models have been used successfully for over twenty years to model test data for radial flow compressors and pumps. The models can also be used to predict the performance of new machines provided that the model inputs can be accurately specified. Unfortunately, use of the TEIS and Two-Zone models as a predictive tool has been limited because an accurate and broadly applicable method of predicting the modeling parameters, etaA, etaB, chi and d2p does not exist. Empirical models have been developed to predict the TEIS and Two-Zone modeling parameters based on a large …

Turbulence Modeling For Film Cooling Flows, Asif Hoda

LSU Doctoral Dissertations

An improved two equation turbulence model has been developed in this dissertation to better predict the complex film cooling flow field that is formed from the interaction of a coolant jet and a crossflow over a modeled turbine blade surface. Film cooling of turbine blades is commonly employed to effectively protect turbine blades from thermal failure and thereby to allow higher inlet temperatures in order to increase the efficiency of gas turbine engines. Film cooling involves the injection of rows of coolant jets from slots on the surface of a turbine blade which is then bent over by the crossflow …

Modeling And Simulation Of A Microturbine Generator To Be Coupled With A Molten Carbonate Fuel Cell For Distributed Generation, Karleine M. Justice

Browse all Theses and Dissertations

Distributed generation is desired when the individual energy requirements ranging from 25-75 kW of office buildings, restaurants, hospitals and apartments can not be met by the current electric utility grid. Microturbine generators as stand alone power generation systems have been designed to meet these requirements. For power requirements up to 50 MW, hybrid fuel cell systems offer higher efficiency and lower levels of pollutant emissions with more advanced fuel energy savings than non-hybrid systems. The objective of this project is to develop a simulation of a microturbine generator as a stand alone power generation system to validate a microturbine generator …