Engineering Commons^™

Experimental Analysis Of Protective Headgear Used In Defensive Softball Play, John Scott Strickland

UNF Graduate Theses and Dissertations

Every year in the United States, an estimated 1.6 to 3.8 million people sustain sports-related traumatic brain injuries (TBIs), with an appreciable number of these injuries coming from the sport of softball. Several studies have analyzed the impact performance of catcher’s masks within the context of baseball; however, virtually no studies have been performed on fielder’s masks within the context of softball. Thus, the main objective of the present work was to evaluate the protective capabilities of softball fielder’s masks. To better understand the injury mechanisms and frequency associated with softball head/facial injuries, epidemiological data from a national database was …

On Learning And Visualizing Lexicographic Preference Trees, Ahmed S. Moussa

UNF Graduate Theses and Dissertations

Preferences are very important in research fields such as decision making, recommendersystemsandmarketing. The focus of this thesis is on preferences over combinatorial domains, which are domains of objects configured with categorical attributes. For example, the domain of cars includes car objects that are constructed withvaluesforattributes, such as ‘make’, ‘year’, ‘model’, ‘color’, ‘body type’ and ‘transmission’.Different values can instantiate an attribute. For instance, values for attribute ‘make’canbeHonda, Toyota, Tesla or BMW, and attribute ‘transmission’ can haveautomaticormanual. To this end,thisthesis studiesproblemsonpreference visualization and learning for lexicographic preference trees, graphical preference models that often are compact over complex domains of objects built of …

A Process, Structure, And Property Study Of Gallium-Based Room Temperature Metallic Alloys, Courtney Lyn Titus

UNF Graduate Theses and Dissertations

Amalgamations are a promising replacement for electronic solders, thermal interface materials, and other conductive joining materials. Amalgams are mechanically alloyed materials of a liquid constituent with a solid powder. Unlike traditional solders, these materials are processed at room temperature or slightly above, and can often operate at temperatures near, or beyond, their processing temperatures. Existing bonding processes require an excessive amount of heat, which may cause thermal stress to the electronic components and delaminate the attachment. Amalgams have promising characteristics for thermal interface materials (TIMs) due to being fully metallic, relatively easy of handling, and possessing metallic strength similar to …

Landing-Gear Impact Response: A Non-Linear Finite Element Approach, Tuan H. Tran

UNF Graduate Theses and Dissertations

The primary objective of this research is to formulate a methodology of assessing the maximum impact loading condition that will incur onto an aircraft’s landing gear system via Finite Element Analysis (FEA) and appropriately determining its corresponding structural and impact responses to minimize potential design failures during hard landing (abnormal impact) and shock absorption testing. Both static and dynamic loading condition were closely analyzed, compared, and derived through the Federal Aviation Administration’s (FAA) airworthiness regulations and empirical testing data.

In this research, a nonlinear transient dynamic analysis is developed and established via NASTRAN advanced nonlinear finite element model (FEM) to …

Reduction Of Nox Emissions In A Single Cylinder Diesel Engine Using Sncr With In-Cylinder Injection Of Aqueous Urea, Anthony Timpanaro

UNF Graduate Theses and Dissertations

The subject of this study is the effect of in-cylinder selective non-catalytic reduction (SNCR) of NO_x emissions in diesel exhaust gas by means of direct injection of aqueous urea ((NH₂)₂CO) into the combustion chamber. A single cylinder diesel test engine was modified to accept an electronically controlled secondary common rail injection system to deliver the aqueous urea directly into the cylinder during engine operation.

Direct in-cylinder injection was chosen in order to ensure precise delivery of the reducing agent without the risk of any premature reactions taking place. Unlike direct in-cylinder injection of neat water, …

A Topic Modeling Approach For Code Clone Detection, Mohammed Salman Khan

UNF Graduate Theses and Dissertations

In this thesis work, the potential benefits of Latent Dirichlet Allocation (LDA) as a technique for code clone detection has been described. The objective is to propose a language-independent, effective, and scalable approach for identifying similar code fragments in relatively large software systems. The main assumption is that the latent topic structure of software artifacts gives an indication of the presence of code clones. It can be hypothesized that artifacts with similar topic distributions contain duplicated code fragments and to prove this hypothesis, an experimental investigation using multiple datasets from various application domains were conducted. In addition, CloneTM, an LDA-based …

Investigating The Effects Of Rainfall On Traffic Operations On Florida Freeways, Lucia Andrew

UNF Graduate Theses and Dissertations

Rainfall affects the performance of traffic operations and endangers safety. A common and conventional method (rain gauges) for rainfall measurements mostly provide precipitation records in hourly and 15-minute intervals. However, reliability, continuity, and wide area coverage pose challenges with this data collection method. There is also a greater likelihood for data misrepresentation in areas where short duration rainfall is predominant, i.e., reported values may not reflect the actual equivalent rainfall intensity during subintervals over the entire reporting period. With recent weather and climate patterns increasing in severity, there is a need for a more effective and reliable way of measuring …

The Use Of Real-Time Connected Vehicles And Here Data In Developing An Automated Freeway Incident Detection Algorithm, Hendry Nyanza Imani

UNF Graduate Theses and Dissertations

Traffic incidents cause severe problems on roadways. About 6.3 million highway crashes are reported annually only in the United States, among which more than 32,000 are fatal crashes. Reducing the risk of traffic incidents is key to effective traffic incident management (TIM). Quick detection of unexpected traffic incidents on roadways contribute to quick clearance and hence improve safety. Existing techniques for the detection of freeway incidents are not reliable.

This study focuses on exploring the potential of emerging connected vehicles (CV) technology in automated freeway incident detection in the mixed traffic environment. The study aims at developing an automated freeway …

Evaluating Mobility And Safety Benefits Of Freeway Service Patrols: A Case Study Of Florida's Road Rangers, Jimoku H. Salum

UNF Graduate Theses and Dissertations

The Florida’s Road Rangers monitor the freeways for incidents to minimize their adverse impacts on traffic. The objectives of this study were to evaluate the extent to which Road Rangers reduce incident clearance duration (ICD), incident-induced traffic delays (IITDs) and secondary crashes (SCs).

Since ICD distributions are often right-skewed, the study applied quantile regression to relate ICD to influencing factors. Data skewed to the right is usually a result of lower bounds in a data set being extremely low relative to the rest of the data. Data from 28,000 incidents that occurred on freeways in Jacksonville, Florida were analyzed. Of …

Evaluating The Performance Of Cooperative Merging Assistance System For Aging Drivers, Flavius Matata

UNF Graduate Theses and Dissertations

Freeway merging maneuvers demand considerable attention by drivers and are among the more complex operations drivers must perform on freeways. Aging drivers, a growing population in the United States, face added challenges when merging. This study utilized Vissim models created in a previous study that modeled the behavior of aging drivers during freeway merging. An algorithm for Cooperative Merging Assistance System (CMAS) that utilizes Connected Vehicle (CV) technology was developed in this study. The Vissim models were created for two interchanges on I-75 in Fort Myers, Florida, each with different geometric characteristics. Acceleration lane lengths of 1000ft and 1500ft were …

Testing Coulwave For Use In Modeling Cross-Shore Sand Transport And Beach Profile Evolution, Patrick Michael Cooper

UNF Graduate Theses and Dissertations

Realistic, reliable, and effective modeling of cross-shore sediment transport is not present in the current literature. Building that model requires the accurate recreation of breaking wave processes in the nearshore. To develop that first step for an as-yet-to-be-designed model, multiple phase-resolving wave transformation algorithms are reviewed for in-depth investigation. The COULWAVE model is selected for robust testing. Testing of the COULWAVE model shows that, although capable of recreating realistic results, it does not adequately describe major wave characteristics in the surf zone, across a wide range of conditions, to warrant use in a future cross-shore sediment transport model.

Evaluating The Mobility And Safety Benefits Of Adaptive Signal Control Technology (Asct), John Herman Kodi

UNF Graduate Theses and Dissertations

The Adaptive Signal Control Technology (ASCT) is a traffic management strategy that optimizes signal timing based on real-time traffic demand. This thesis proposes a comprehensive methodology of quantifying the mobility and safety benefits of the ASCT deployed in the state of Florida. A Bayesian switch-point regression model was proposed to evaluate the mobility benefits of ASCT. The analysis was based on a 3.3-mile corridor along Mayport Road from Atlantic Boulevard to Wonderwood Drive in Jacksonville, Florida. The proposed analysis was used to estimate the possible dates that separate the two operating characteristics, i.e., with and without ASCT. Also, the posterior …

Simulation Exploration Of The Potential Of Connected Vehicles In Mitigating Secondary Crashes, Mike Alvin Soloka

UNF Graduate Theses and Dissertations

Secondary crashes (SCs) on freeways are a major concern for traffic incident management systems. Studies have shown that their occurrence is significant and can lead to deterioration of traffic flow conditions on freeways in addition to injury and fatalities, albeit their magnitudes are relatively low when compared to primary crashes. Due to the limited nature of crash data in analyzing freeway SCs, surrogate measures provide an alternative for safety analysis for freeway analysis using conflict analysis. Connected Vehicles (CVs) have seen compelling technological advancements since the concept was introduced in the 1990s. In recent years, CVs have emerged as a …

An Analysis Of Hydroacoustic Transmission Loss Associated With Marine Pile Driving, Jonathan Paul Berube

UNF Graduate Theses and Dissertations

There has been a growing concern in recent years about the effects of anthropogenic noise due to marine pile driving on underwater wildlife. Current guidelines for mitigating hydroacoustic effects associated with these events are based upon relatively simple transmission loss formulations. The advantage to these guidelines is that computing transmission loss using their prescribed methods is not labor intensive, but their disadvantage is that they may not take all variables into account. Because of this, it may be possible to improve transmission loss computations. To better-characterize marine pile driving sound transmission loss, a unique in-water instrumentation system was developed. This …

Development, Validation, And Utilization, Of A Long-Term Nearshore Synthetic Wave Record, Sergio A. Pena

UNF Graduate Theses and Dissertations

The need for a consistent and accurate production of long-term nearshore wave record is discussed. With multiple decades of offshore hindcasts and long, continuous data sets available, it is possible to create a nearshore synthetic wave record. The Brevard County coastline offers an area with a high quality 62-year long offshore hindcast, as well as an 11-year long and nearly continuous high-resolution nearshore wave record to compare with model performance. This thesis presents the steps in the development and performance of the synthetic nearshore wave record produced. A novel approach was used to compare, validate and calibrate this type of …

Trapping Aco Applied To Mri Of The Heart, Shannon Lloyd Birchell

UNF Graduate Theses and Dissertations

The research presented here supports the ongoing need for automatic heart volume calculation through the identification of the left and right ventricles in MRI images. The need for automated heart volume calculation stems from the amount of time it takes to manually processes MRI images and required esoteric skill set. There are several methods for region detection such as Deep Neural Networks, Support Vector Machines and Ant Colony Optimization. In this research Ant Colony Optimization (ACO) will be the method of choice due to its efficiency and flexibility. There are many types of ACO algorithms using a variety of heuristics …

Operational Effectiveness Of Connected Vehicle Smartphone Technology On A Signalized Corridor, Festo Mjogolo

UNF Graduate Theses and Dissertations

Over the last decade, extensive research efforts have been placed on performance evaluation and the benefits of innovative CV applications. Findings indicate that CV technology can effectively mitigate the safety, mobility, and environmental challenges experienced on transportation networks. Most of research evaluated CV technology through simulation studies. However, a field study provides a more ideal method of assessing CV technology effectiveness. Therefore, a field study to obtain the actual effectiveness of CV technology was warranted, to validate previous findings, and to add to the body of knowledge surrounding this topic. This thesis presents both a field study and simulation evaluation …

The Operational And Safety Effects Of Heavy Duty Vehicles Platooning, Ahmed Alzahrani

UNF Graduate Theses and Dissertations

Abstract

Although researchers have studied the effects of platooning, most of the work done so far has focused on fuel consumption. There are a few studies that have targeted the impact of platooning on the highway operations and safety. This thesis focuses on the impact of heavy-duty vehicles (HDVs) platooning on highway characteristics. Specifically, this study aims at evaluating the effects of platooning of HDVs on capacity, safety, and CO₂ emissions.

This study is based on a hypothetical model that was created using the VISSIM software. VISSIM is a powerful simulation software designed to mimic the field traffic flow …

Modeling Context-Adaptive Energy-Aware Security In Mobile Devices, Preeti Singh

UNF Graduate Theses and Dissertations

As increasing functionality in mobile devices leads to rapid battery drain, energy management has gained increasing importance. However, differences in user’s usage contexts and patterns can be leveraged for saving energy. On the other hand, the increasing sensitivity of users’ data, coupled with the need to ensure security in an energy-aware manner, demands careful analyses of trade-offs between energy and security. The research described in this thesis addresses this challenge by 1)modeling the problem of context-adaptive energy-aware security as a combinatorial optimization problem (Context-Sec); 2) proving that the decision version of this problem is NP-Complete, via a reduction from a …

A Study On Erosion Resistance For Microbially Induced Calcite Treated Beach Sand, Abigail Chek

UNF Graduate Theses and Dissertations

Microbial induced calcite precipitation (MICP) was used to treat several sandboxes filled with naturally occurring beach sand collected from Atlantic Beach, FL. Unlike most previous MICP studies, a surface-spray technique was used to treat these sandboxes where relatively high-concentration bacteria solution and high concentration calcium chloride/urea solutions were applied directly to the boxes’ surfaces. Several different treatment combinations were tested whereby bacterial optical density, bacteria/urea/calcium chloride volume relative to void space, and bacteria/urea/calcium chloride ratio were manipulated. Treated sandboxes were tested for erodibility using a pocket erodometer and for calcification using a wash method. In addition, sandboxes were dissected after …