Engineering Commons^™

Numerical Modeling Of Soy Biodiesel To Maximize Engine Power And Efficiency While Minimizing Pollutant Emissions, Ehsan Tootoonchi

Theses and Dissertations

Biodiesel is a renewable fuel that can help to reduce dependence on foreign petroleum and to help control the negative environmental effects of combustion engines. This work develops a numerical model for soy biodiesel combustion in diesel engine applications. A comprehensive breakup model for diesel and biodiesel combustion calculations using the KIVA- 3V is presented. The primary breakup model calculates the outcome of the initial breakup stage using flow conditions, nozzle geometry, and liquid fuel characteristics, and assigns the Sauter Mean Radius (SMR) values to injecting droplets. The Kelvin-Helmholtz/Rayleigh-Taylor(KH-RT) model acts as the secondary model to break up injected particles. …

The Controlled Human Gyroscope, Randy Claude Arjunsingh

Theses and Dissertations

The objective of this thesis was to design an adaptive rotational motion simulator capable of replicating the attitudes of spacecrafts and aircrafts, while avoiding gimbal lock. Flight motion simulators are currently used for flight training and research, but there are many limitations to these existing systems. This thesis presents a low-cost design for a rotational motion platform titled, ‘The Controlled Human Gyroscope’. It uses a 4-axis system instead of the conventional 3-axis system to avoid gimbal lock and prevent the unnecessary motion of the user. The Human Gyroscope features unlimited rotation about the roll, pitch and yaw axes regardless of …

The Eco-Friendly Intermodal Delivery Network, Sergio Mourelo

Senior Honors Theses

The design of the distribution process is a strategic issue for almost every company. As the use of advanced technology and automation increases in manufacturing and logistics, the implementation of autonomous and electrical transportation, such as driverless vehicles and electric trucks, has become an interesting topic of study within the last few years, with the main objective of minimizing distribution costs and delivery times. The purpose of this research is to prove that intermodal delivery networks, which may combine a train and several electric vehicles, are more efficient and environmentally friendly than unimodal networks for high volume and long haul …

On The Importance Of Displacement History In Soft-Body Contact Models, Jonathan A. Fleischmann, Radu Serban, Dan Negrut, Paramsothy Jayakumar

Mechanical Engineering Faculty Research and Publications

Two approaches are commonly used for handling frictional contact within the framework of the discrete element method (DEM). One relies on the complementarity method (CM) to enforce a nonpenetration condition and the Coulomb dry-friction model at the interface between two bodies in mutual contact. The second approach, called the penalty method (PM), invokes an elasticity argument to produce a frictional contact force that factors in the local deformation and relative motion of the bodies in contact. We give a brief presentation of a DEM-PM contact model that includes multi-time-step tangential contact displacement history. We show that its implementation in an …

Open Source Laser Polymer Welding System: Design And Characterization Of Linear Low-Density Polyethylene Multilayer Welds, John Laureto, Serguei V. Dessiatoun, Michael M. Ohadi, Joshua M. Pearce

Department of Materials Science and Engineering Publications

The use of lasers to weld polymer sheets provides a means of highly-adaptive and custom additive manufacturing for a wide array of industrial, medical, and end user/consumer applications. This paper provides an open source design for a laser polymer welding system, which can be fabricated with low-cost fused filament fabrication and off-the-shelf mechanical and electrical parts. The system is controlled with free and open source software and firmware. The operation of the machine is validated and the performance of the system is quantified for the mechanical properties (peak load) and weld width of linear low density polyethylene (LLDPE) lap welds …

A Tool For Downscaling Weather Data From Large-Grid Reanalysis Products To Finer Spatial Scales For Distributed Hydrological Applications, Avirup Sen Gupta, David G. Tarboton

Civil and Environmental Engineering Faculty Publications

A downscaling tool was developed to provide sub-daily high spatial resolution surfaces of weather variables for distributed hydrologic modeling from NASA Modern Era Retrospective-Analysis for Research and Applications reanalysis products. The tool uses spatial interpolation and physically based relationships between the weather variables and elevation to provide inputs at the scale of a gridded hydrologic model, typically smaller (∼100 m) than the scale of weather reanalysis data (∼20–200 km). Nash-Sutcliffe efficiency (NSE) measures greater than 0.70 were obtained for direct tests of downscaled daily temperature and monthly precipitation at 173 SNOTEL sites. In an integrated test driving the Utah Energy …

Deposition Of Carbon Nanotube Films On Polyamide And Polypropylene Substrates: A Computer Simulation Approach, Alejandro Heredia, Maria Colin-Garcia, Maria Del Pilar Carreon-Castro, Debarati Mukherjee, Bruno Abreu, David William Britt, Joana Catarina Mendes

Biological Engineering Faculty Publications

In this work we study hydroxylated carbon nanotube (CNT) assembly on polyamide (PA) and polypropylene (PP) polymers activated by UV radiation from a theoretical and experimental perspective. Molecular computer simulation was done to understand the stable conformations and bulk properties (molecular dynamics) of the polymers before and after exposure to UV radiation at the molecular level. Our experiments suggest that PA presents more -OH active groups, producing a more hydrophilic surface, whereas PP exhibits less potential UV activation. These results suggest that it is possible a facile covalent functionalization method to tune organic polymer surface properties through SWCNT anchoring for …

Use Of Cycling Paths Along The Morogoro Brt Line, Ford Sanger

Independent Study Project (ISP) Collection

As the urban population continues to increase rapidly in Dar es Salaam it will become increasingly important to find sustainable means of urban transportation. With planned infrastructure improvements in the city to help alleviate traffic congestion, bicycles, which represent a largely underutilized form of urban transportation, have the potential to play a large role in the future of the city. Through background research, direct observations, community surveys, and interviews, both formal and informal, this study sought to understand the impact of the recent addition of bike lanes along the first phase of the Dar Bus Rapid Transit line. It was …

Advanced Technologies For Sustainable Systems, Hesham Safwat

Mechanical Engineering

No abstract provided.

The Effects Of Is-Bao Implementation And Leadership Performance On Safety Culture In Business Aviation Flight Operations, Christopher Mark Broyhill

Doctoral Dissertations and Master's Theses

The International Standard, Business Aircraft Operations (IS-BAO), with a Safety Management System (SMS) as its core element, has been widely accepted by both the International Civil Aviation Organization (ICAO) and the business aviation industry as the mechanism to create a healthy safety culture among the business aviation operators who have implemented the standard. Scholarly literature, however, has presented leadership as the most important factor in the creation and management of a healthy safety culture in organizations in general and aviation organizations in particular. This study examined and compared the effects of IS-BAO progression and leadership performance on the perceptions of …

The Effect Of Generation On Retention Of Women Engineers In Aerospace And Industry, Kristine Maria Kiernan

Doctoral Dissertations and Master's Theses

The purpose of this dissertation was to determine the nature and extent of differences between generational cohorts regarding the effect of family factors on retention of women in engineering, with an emphasis on women in the aerospace industry. While 6% of the aerospace workforce is made up of aeronautical engineers, an additional 11.2% of the aerospace workforce is drawn from other engineering disciplines. Therefore, the analysis included all engineering sub-disciplines. In order to include women who had left the workforce, women in all industries were used as a proxy for women in aerospace.

Exits to other fields were modeled separately …

The Effects Of Safety Culture And Ethical Leadership On Safety Performance, Kevin O’Leary

Doctoral Dissertations and Master's Theses

This dissertation investigated the effects of safety culture and ethical leadership on safety performance in Fractional jet pilots in the United States. The primary objective was to develop a well-fitted model linking these constructs. A composite survey instrument was developed from instruments previously validated in the literature.

There were 305 complete and valid responses from Fractional pilots. The hypothesized factor structure consisted of seven factors. The exogenous factor of safety culture was made up of four sub-factors. The endogenous factors included ethical leadership, pilot commitment, and safety performance. Safety performance was a second order factor consisting of errors and attitudes …

Column-Grid-Array (Cga) Versus Ball-Grid-Array (Bga): Boardlevel Drop Test And The Expected Dynamic Stress In The Solder Material, Ephraim Suhir, Reza Ghaffarian

Mechanical and Materials Engineering Faculty Publications and Presentations

Board level drop test is considered with an objective to develop a physically meaningful analytical predictive model for the evaluation of the expected impactinduced dynamic stresses in the solder material. Ball-gridarray (BGA) and column-grid-array (CGA) designs are addressed. Intuitively it is felt that while the application of the CGA technology to relieve thermal stresses in the solder material might be quite effective (owing to the greater interfacial compliance of the CGA in comparison with the BGA), the situation might be quite different when the PCB/package experiences dynamic loading. This is because the mass of the CGA joints exceeds considerably that …

Optimal Design Of Ipm Motors With Different Cooling Systems And Winding Configurations, Alireza Fatemi, Dan M. Ionel, Nabeel Demerdash, Thomas W. Nehl

Electrical and Computer Engineering Faculty Research and Publications

Performance improvement of permanent magnet (PM) motors through optimization techniques has been widely investigated in the literature. Oftentimes the practice of design optimization leads to derivation/interpretation of optimal scaling rules of PM motors for a particular loading condition. This paper demonstrates how these derivations vary with respect to the machine ampere loading and ferrous core saturation level. A parallel sensitivity analysis using a second-order response surface methodology followed by a large-scale design optimization based on evolutionary algorithms are pursued in order to establish the variation of the relationships between the main design parameters and the performance characteristics with respect to …

Fast Multi-Objective Cmode-Type Optimization Of Pm Machines Using Multicore Desktop Computers, Alireza Fatemi, Dan M. Ionel, Nabeel Demerdash, Thomas W. Nehl

Electrical and Computer Engineering Faculty Research and Publications

Large-scale design optimization of electric machines is oftentimes practiced to achieve a set of objectives, such as the minimization of cost and power loss, under a set of constraints, such as maximum permissible torque ripple. Accordingly, the design optimization of electric machines can be regarded as a constrained optimization problem (COP). Evolutionary algorithms (EAs) used in the design optimization of electric machines including differential evolution (DE), which has received considerable attention during recent years, are unconstrained optimization methods that need additional mechanisms to handle COPs. In this paper, a new optimization algorithm that features combined multi-objective optimization with differential evolution …

Configuration And Optimization Of A Novel Compressed-Air-Assisted Wind Energy Conversion System, Jie Cheng

Department of Electrical and Computer Engineering: Dissertations, Theses, and Student Research

The increasing concerns over the environmental impact of carbon emissions and the unsustainability of conventional fossil fuel power plants are stimulating interest in the implementation of renewable energy in current power systems. Among all of the renewable energies, wind energy holds a prominent place because of its high output and the maturity of the technology. However, like all of the other renewable energies, integration of wind energy into the power grid causes some quality and control issues, such as overvoltage or undervoltage and frequency excursion.

To mitigate these issues and build a robust wind power system, a novel structure referred …

Pythagorean Combinations For Lego Robot Building., Ronald I. Greenberg

Computer Science: Faculty Publications and Other Works

This paper provides tips for LEGO robot construction involving bracing or gear meshing along a diagonal using standard Botball kits.

An Information Model In The Domain Of Disassembly Planning For Sustainable Manufacturing, Bicheng Zhu

Dissertations - ALL

Disassembly, a process of separating the End of Life (EOL) product into discrete components for re-utilizing their associated residual values, is an important part for the sustainable manufacturing. This work focuses on the modeling of the disassembly planning related information, and develops a Disassembly Information Model (DIM) based on an extensive investigation of various informational aspects of the disassembly planning. The developed Disassembly Information Model, which represents an appropriate systematization and classification of the products, processes, uncertainties and degradations related information, follows a layered modeling methodology. In this layered configuration, the DIM is subdivided into three distinct layers with an …

Cfd Study Of Decay Function Of Wall Shear Stress With Scour Around Complex-Shape Bridge Pier, Chen Li

Department of Civil and Environmental Engineering: Dissertations, Theses, and Student Research

Pier scour problem is close related to the safety of bridges. The Federal Highway Administration of the United State also has a great interest in studying the relation between hydraulic loadings and scour depth. The current technological problem of directly measuring hydraulic loadings on a dynamic bed using physical experiments and the weak capacity to simulate the real scour processes with CFD methods inspired the development of a hybrid approach by combining them to study pier scour.

This research specifically focuses on the CFD part of the hybrid method. A series of three-dimensional (3-D) CFD models were developed with unsteady …

Wide Bandgap Organo‐Lead Trihalide Perovskites For Solar Cells, Miao Hu

Department of Mechanical and Materials Engineering: Dissertations, Theses, and Student Research

Methylammonium lead trihalide perovskite (MAPbX3, where MA is methylammonium, and X is a halide)-based solar cells have been extensively investigated recently, with a demonstrated and certified solar power conversion efficiency (PCE) exceeding 20%. To further boost the PCE beyond the Schockley–Queisser limit, tandem structured solar cells have been investigated based on integrating MAPbX3 and the lower bandgap solar cells. Although the best reported efficiency for this type of tandem cells is not close to the theoretically achievable value, mixed-halide perovskite MAPbBrxI3–x is still one of the most promising candidates as the wide-bandgap light absorber for the tandem application to match …

Cascading Failures In Interdependent Infrastructures: An Interdependent Markov-Chain Approach, Mahshid Rahnamay-Naeini, Majeed M. Hayat

Electrical and Computer Engineering Faculty Research and Publications

Many critical infrastructures are interdependent networks in which the behavior of one network impacts those of the others. Despite the fact that interdependencies are essential for the operation of critical infrastructures, such interdependencies can negatively affect the reliability and fuel the cascade of failures within and across the networks. In this paper, a novel interdependent Markov-chain framework is proposed that enables capturing interdependencies between two critical infrastructures with the ultimate goal of predicting their resilience to cascading failures and characterizing the effects of interdependencies on system reliability. The framework is sufficiently general to model cascading failures in any interdependent networks; …

Probabilistic Anomaly Detection In Natural Gas Time Series Data, Hermine Nathalie Akouemo Kengmo Kenfack, Richard J. Povinelli

Electrical and Computer Engineering Faculty Research and Publications

This paper introduces a probabilistic approach to anomaly detection, specifically in natural gas time series data. In the natural gas field, there are various types of anomalies, each of which is induced by a range of causes and sources. The causes of a set of anomalies are examined and categorized, and a Bayesian maximum likelihood classifier learns the temporal structures of known anomalies. Given previously unseen time series data, the system detects anomalies using a linear regression model with weather inputs, after which the anomalies are tested for false positives and classified using a Bayesian classifier. The method can also …

Research Note: On The Magnitude Of Error In The Calculation Of Mean Room Surface Exitance, James Duff

Articles

Two formulae currently exist for calculating mean room surface exitance. This research note explains and demonstrates that one of these formulae is erroneous under certain conditions and stresses that the alternative expression should generally be used for computing mean room surface exitance.

Simplified Performance-Based Analysis For Seismic Slope Displacements, Marlem Lucia Astorga Mejia

Theses and Dissertations

Millions of lives have been lost over the years as a result of the effects of earthquakes. One of these devastating effects is slope failure, more commonly known as landslide. Over the years, seismologists and engineers have teamed up to better record data during an earthquake. As technology has advanced, the data obtained have become more refined, allowing engineers to use the data in their efforts to estimate earthquakes where they have not yet occurred. Several methods have been proposed over time to utilize the earthquake data and estimate slope displacements. A pioneer in the development of methods to estimate …

Differential Association Of Vitronectin And Fibronectin With Glass And Electrospun Fibers Of A Poly (D-Lysine) /Poly (Acrylic Acid), Syed Muhammad Sohaib Zafar Zafar

USF Tampa Graduate Theses and Dissertations

Proteins represent major constituent of the extracellular matrix which plays an important role in the formation, maintenance and remodeling of tissues, this project focuses on adsorption of two specific serum proteins fibronectin (FN) and vitronectin (VTN) responsible for mediating cell matrix interaction through integrin binding, tripeptide Arg-Gly-Asp (RGD) sequence found in these protein features are recognized by αβV₃ integrin which ultimately helps in clot formation.

Automated Device To Measure Slurry Properties In Drilled Shafts, Miles Patrick Mullins

USF Tampa Graduate Theses and Dissertations

Slurry is the fluid within a drilled excavation that is introduced when an excavation is deeper than the water table or where additional stability is needed for loose sandy dry soils. Although construction practices vary greatly throughout the country and the world, slurry levels should be maintained above the existing ground water level by a suitable margin. The most widely used slurry type is mineral slurry formed by mixing dry clay powder with water; either bentonite or attapulgite powder may be used (attapulgite being used in saline water conditions). Regardless of whether the slurry material is mineral, polymer or natural, …

Properties In Hardness Of Al-Cu Couples Diffused At 813 K, J Hinojosa-Torres, Jm Aceves-Hernández

Journal of Metals, Materials and Minerals

Al-Cu couples were heated to 813 K during 200, 320 and 480 hours. The heat treatment conditions caused the welding of the metals. After the mentioned conditions, it was observed the formation of two contiguous plates like (~15 to 30 micrometres, width) in parallel direction to the contact section. These plates like were chemically identified and its compositions corresponded to the h2 (CuAl) phase and to the q (CuAl2) phase of the aluminium-copper system. The measurements of micro hardness that were carried out on these plates like gave values of 620HV0.05 and 500HV0.05 (on the average) respectively. In the Cu-rich …

Aviation And Cybersecurity: Opportunities For Applied Research, Jon Haass, Radhakrishna Sampigethaya, Vincent Capezzuto

Publications

Aviation connects the global community and is moving more people and payloads faster than ever. The next decade will experience an increase in manned and unmanned aircraft and systems with new features and unprecedented applications. Cybertechnologies—including software, computer networks, and information technology—are critical and fundamental to these advances in meeting the needs of the aviation ecosystem of aircraft, pilots, personnel, passengers, stakeholders, and society. This article discusses current and evolving threats as well as opportunities for applied research to improve the global cybersecurity stance in the aviation and connected transportation industry of tomorrow.

Predicting General Aviation Pilots’ Weather-Related Performance Through A Scenario-Based Written Assessment, Jessica Cruit

Doctoral Dissertations and Master's Theses

Weather-related accidents continue to challenge the general aviation community and with the development of advanced weather technology, GA pilots need additional education and training on how to effectively use these weather products to ensure flight safety. Currently, the literature on aviation weather suggests that there is a gap in both training and assessment strategy for GA pilots. Furthermore, several studies suggest that there needs to be more assessment of weather-related scenario/application questions for the private pilot’s written knowledge exam in order to assess a deeper level of knowledge for weather-related material. The purpose of this study is to design a …

Bioaugmentation And Correlating Anaerobic Digester Microbial Community To Process Function, Kaushik Venkiteshwaran

Dissertations (1934 -)

This dissertation describes two research projects on anaerobic digestion (AD) that investigated the relationship between microbial community structure and digester function. Both archaeal and bacterial communities were characterized using high-throughput (Illumina) sequencing technology with universal 16S rRNA gene primers. In the first project, bioaugmentation using a methanogenic, aerotolerant propionate enrichment culture was investigated as a possible method to increase digester methane production. Nine anaerobic digesters, seeded with different biomass, were operated identically and their quasi steady state function was compared. Before bioaugmentation, different seed biomass resulted in different quasi steady state function, with digesters clustering into high, medium or low …