Engineering Commons^™

Long-Term Biofilm Tests With Silver Contained Electrospun Polymer Mats, Bo Peng

Dissertations - ALL

It has been reported that wounds heal faster and better in a moist, enclosed environment. Wound dressings are designed to fulfill such demands. In addition, wound dressings protect wounds from subsequent physical harm and bacterial infection. Among various types of wound dressings, electrospun wound dressings are widely marketed due to desired properties. For instance, electrospun polymers are highly porous. Water and oxygen that are necessary for cells are permeable through the porous structure. Moreover, electrospun polymers have high surface area to volume ratio. This property allows polymers to absorb extra exudate from wounds efficiently. In this study, several silver-releasing electrospun …

Pressure Reduction On Wide Culverts With Eps Geofoam Backfill, Stephen Singh

Dissertations - ALL

Buried structures may be subjected to excessive stresses that are detrimental to their expected service life. A review of previous design methods shows that there are effective methods to reduce loadings on narrow culverts. The Induced Trench Method introduces compressible fill over a buried structure to mobilize positive arching, and transfer stresses to the side fills. However, this method has not been studied with Bridge Culverts (large spanning culverts). This study evaluates the use of EPS (Expanded Polystyrene, Geofoam) as a compressible/lightweight fill material. The displacements and stresses of the classic narrow trench are examined in detail using the finite …

Identification Of Key Players In Networks Using Multi-Objective Optimization And Its Applications, R Chulaka Gunasekara

Dissertations - ALL

Identification of a set of key players, is of interest in many disciplines such as sociology, politics, finance, economics, etc. Although many algorithms have been proposed to identify a set of key players, each emphasizes a single objective of interest. Consequently, the prevailing deficiency of each of these methods is that, they perform well only when we consider their objective of interest as the only characteristic that the set of key players should have. But in complicated real life applications, we need a set of key players which can perform well with respect to multiple objectives of interest.

In this …

Risk-Aware Planning For Sensor Data Collection, Jeffrey Hudack

Dissertations - ALL

With the emergence of low-cost unmanned air vehicles, civilian and military organizations are quickly identifying new applications for affordable, large-scale collectives to support and augment human efforts via sensor data collection. In order to be viable, these collectives must be resilient to the risk and uncertainty of operating in real-world environments. Previous work in multi-agent planning has avoided planning for the loss of agents in environments with risk. In contrast, this dissertation presents a problem formulation that includes the risk of losing agents, the effect of those losses on the mission being executed, and provides anticipatory planning algorithms that consider …

On The Design And Analysis Of Secure Inference Networks, Venkata Sriram Siddhardh Nadendla

Dissertations - ALL

Parallel-topology inference networks consist of spatially-distributed sensing agents that collect and transmit observations to a central node called the fusion center (FC), so that a global inference is made regarding the phenomenon-of-interest (PoI). In this dissertation, we address two types of statistical inference, namely binary-hypothesis testing and scalar parameter estimation in parallel-topology inference networks. We address three different types of security threats in parallel-topology inference networks, namely Eavesdropping (Data-Confidentiality), Byzantine (Data-Integrity) or Jamming (Data-Availability) attacks. In an attempt to alleviate information leakage to the eavesdropper, we present optimal/near-optimal binary quantizers under two different frameworks, namely differential secrecy where the difference …

Understanding And Improving Security Of The Android Operating System, Edward Paul Ratazzi

Dissertations - ALL

Successful realization of practical computer security improvements requires an understanding and insight into the system's security architecture, combined with a consideration of end-users' needs as well as the system's design tenets. In the case of Android, a system with an open, modular architecture that emphasizes usability and performance, acquiring this knowledge and insight can be particularly challenging for several reasons. In spite of Android's open source philosophy, the system is extremely large and complex, documentation and reference materials are scarce, and the code base is rapidly evolving with new features and fixes. To make matters worse, the vast majority of …

Structure, Dynamics And Rheology Of Surfactant Micelles And Micelle-Nanoparticle Solutions: A Molecular Dynamics Study, Abhinanden Sambasivam

Dissertations - ALL

Surfactant micelles are widely used in a number of industrial, commercial and household products and processes. Understanding flow-microstructure coupling in micellar systems can benefit applications ranging from targeted drug delivery and detergency to enhanced oil recovery and hydrofracking. Amongst micellar fluids, wormlike micelles (WLMs) are extremely interesting due to their structural similarity to polymers and their ability to constantly undergo scission and recombination at equilibrium. More recently, much has been generated in studying the effect of adding colloidal particles to WLMs. Colloidal particles can not only add functionality to the fluid but also act as viscosity modifiers. Such solutions can …

Plasma Processes And Polymers Third Special Issue On Plasma And Cancer, Mounir Laroussi, Annemie Bogaerts, Nazir Barekzi

Electrical & Computer Engineering Faculty Publications

(First paragraph) This issue of Plasma Processes and Polymers is the third in a series on the applications of low temperature plasma (LTP) against cancer, or “plasma oncology.” The papers in this issue are inspired from the talks given at the third International Workshop on Plasma for Cancer Treatment (IWPCT) which took place on April 11–12, 2016 in Washington, DC, USA. IWPCT is an international workshop that was created in 2014 as a venue to share cutting edge plasma oncology research. The first IWPCT was held in Washington DC, under the co-chairmanship of Prof. Mounir Laroussi (Old Dominion University) and …

Using Blind Source Separation And A Compact Microphone Array To Improve The Error Rate Of Speech Recognition, Jeffrey Dean Hoffman

Dissertations and Theses

Automatic speech recognition has become a standard feature on many consumer electronics and automotive products, and the accuracy of the decoded speech has improved dramatically over time. Often, designers of these products achieve accuracy by employing microphone arrays and beamforming algorithms to reduce interference. However, beamforming microphone arrays are too large for small form factor products such as smart watches. Yet these small form factor products, which have precious little space for tactile user input (i.e. knobs, buttons and touch screens), would benefit immensely from a user interface based on reliably accurate automatic speech recognition.

This thesis proposes a solution …

Causes And Impacts Of Geotechnical Problems On Bridge And Road Construction Projects, Krishna Prasad Neupane

UNLV Theses, Dissertations, Professional Papers, and Capstones

Changes during the construction phase generate cost growth, schedule delays, and claims in any project. However, the impact of geotechnical problems on construction costs, schedules, and claims in bridge and road projects had not been investigated in depth. The major objectives of this study were to determine the geotechnical-related causes of cost and schedule growth and claims as well as their impacts on the bridge and pavement projects’ performance. This study also identifies mitigation measures to avoid cost and schedule growth and claims in these projects.

A survey was conducted with 53 engineers from state Department of Transportations (DOTs) and …

Occurrence And Proliferation Of Antibiotics And Antibiotic Resistance In Wastewater Treatment Plants, Majid Neyestani

UNLV Theses, Dissertations, Professional Papers, and Capstones

Solids retention time (SRT) is one of the most important factors in designing and operating activated sludge systems for biological wastewater treatment. Longer SRTs have been shown to alter the structure and function of microbial communities, thereby leading to improved treatment efficacy with respect to bulk and trace organics, nutrient removal, and membrane fouling. However, research has also shown that longer SRTs lead to increased prevalence of antibiotic resistant bacteria, perhaps due to increased exposure to antibiotics present in influent wastewater. The purpose of this study was to characterize changes in microbial community structure in a laboratory-scale activated sludge system …

Adaptive Background Modeling With Temporal Feature Update For Dynamic Foreground Object Removal, Li Yin

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

This thesis explores several approaches in order to develop an effective algorithm for separating the moving objects from the background so that the background alone may be displayed in a video sequence. In particular, this thesis seeks to develop an algorithm that can successfully remove a moving teacher from the whiteboard, so that the writing on the whiteboard may be fully visible to the audience.

In this thesis, some prior works related to this problem are studied to understand the basic principles of adaptive background modeling, or removing the foreground from a background with occasional changes in a video sequence. …

Factors Affecting Social Sustainability In Highway Projects In Missouri, Mohamed Abdel-Raheem, Charles Ramsbottom

Civil Engineering Faculty Publications

Sustainability focuses on the interaction between a given project and the social, environmental, and the economic dimensions of the system enclosing it. The majority of the studies conducted focused mostly on the environmental aspects of sustainability rather than the economic ones, while very few studies discussed the social dimension. Social sustainability promotes the concepts of respect, awareness, diversity, vitality, and responsibility toward the workforce and the society by keeping them healthy and safe from harm during the different phases of a project. Highway projects are one of the most critical infrastructure projects in the construction industry. This is due to …

Spatial Distribution Of Antibiotic Resistance In Soils Receiving Beef Feedlot Runoff, Scott Speicher

Department of Environmental Engineering: Theses and Other Student Research

A study was conducted to provide new insight on the potential contribution to antibiotic resistance from the land application of beef feedlot runoff to soil. This study reports the distribution and quantity of antibiotic resistant bacteria (ARBs), fecal indicator bacteria (FIB), and antibiotic resistance genes (ARGs) in soil from (i) a field receiving long-term application of beef feedlot runoff holding pond effluent and (ii) a cool-season pasture with no history of supplemental manure application.

Soil samples were collected June 2015 at the U.S. Meat Animal Research Center near Clay Center, Nebraska. A response surface sampling design (RSSD) model based on …

Optimal Grading For Strength And Functionality Of Parts Made Of Interpenetrating Polymer Networks: Load Capacity Enhancement, Zhong Chen

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

Uniform parts with stress concentrations or singularities are prone to failure under relatively small loads, which motivates researchers to seek methods to enhance the strength of these parts. This dissertation studies the optimization of material grading to design parts made of functionally graded interpenetrating polymer networks (FG-IPNs) to improve their load capacity.

An acrylate/epoxy IPN with variations of elastic Young’s modulus, Poisson’s ratio, and ultimate stress at failure is used for optimization of a plate with stress concentration. The grading is optimized by attaching the finite element method (FEM) solver to a general purpose bound-constrained optimizer. Two examples, a plate …

Design Of A Flexible Control Platform And Miniature In Vivo Robots For Laparo-Endoscopic Single-Site Surgeries, Lou P. Cubrich

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

Minimally-invasive laparoscopic procedures have proven efficacy for a wide range of surgical procedures as well as benefits such as reducing scarring, infection, recovery time, and post-operative pain. While the procedures have many advantages, there are significant shortcomings such as limited instrument motion and reduced dexterity. In recent years, robotic surgical technology has overcome some of these limitations and has become an effective tool for many types of surgeries. These robotic platforms typically have an increased workspace, greater dexterity, improved ergonomics, and finer control than traditional laparoscopic methods. This thesis presents the designs of both a four degree-of-freedom (DOF) and 5-DOF …

Models For Decanting Gaseous Fuel Tanks: Simulations With Gfssp Thermal Model, Kailash Kumar Jain Munoth

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

Transport of fuel from distillation/storage plant to different parts of the world has always been challenging task for Engineers. Different methods have been proposed over the time for transporting fuel efficiently and at low cost which include Marine vessels, Pipelines, Rail Cars and Trucks. In order to transport useful amount of fuel in a reasonably sized tank, we have to liquefy it. While few fuels are easy to liquefy there are great number of fuels which liquefy only under extreme pressure/temperature conditions. Methane has a boiling point of -161.7°C at atmospheric pressure which means it has to be cooled to …

Dynamic Responses Of Wheel-Rail Systems With Block Dampers, Tzuyu Tseng

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

The wheel-rail interaction problem has been widely studied in the past few decades. In this problem, dynamic responses at the contact areas remain the central issue since they induce damage to the rail over time. In particular, the dynamic responses at the contact areas between the wheels and rails present difficulties in understanding and mathematical modeling. Even with the computer power one has today, its mathematical modeling employs the versatile numerical analysis method, the finite element method (FEM) remains a formidable challenge due to its extremely small contact areas and in turn the extremely high stress levels. In addition, friction …

Predicting The Performance Of Queues: A Data Analytic Approach, Kum Khiong Yang, Cayirli Tugba, Mei Wan Low

Research Collection Lee Kong Chian School Of Business

Existing models of multi-server queues with system transience and non-standard assumptions are either too complex or restricted in their assumptions to be used broadly in practice. This paper proposes using data analytics, combining computer simulation to generate the data and an advanced non-linear regression technique called the Alternating Conditional Expectation (ACE) to construct a set of easy-to-use equations to predict the performance of queues with a scheduled start and end time. Our results show that the equations can accurately predict the queue performance as a function of the number of servers, mean arrival load, session length and service time variability. …

Safety Performance Prediction Of Large-Truck Drivers In The Transportation Industry, Emily Moneka Francis Xavier

Graduate Theses and Dissertations

The trucking industry and truck drivers play a key role in the United States commercial transportation sector. Accidents involving large trucks is one such big event that can cause huge problems to the driver, company, customer and other road users causing property damage and loss of life. The objective of this research is to concentrate on an individual transportation company and use their historical data to build models based on statistical and machine learning methods to predict accidents. The focus is to build models that has high accuracy and correctly predicts an accident. Logistic regression and penalized logistic regression models …

Grouping Techniques To Manage Large-Scale Multi-Item Multi-Echelon Inventory Systems, Anvar Abaydulla

Graduate Theses and Dissertations

Large retail companies operate large-scale systems which may consist of thousands of stores. These retail stores and their suppliers, such as warehouses and manufacturers, form a large-scale multi-item multi-echelon inventory supply network. Operations of this kind of inventory system require a large number of human resources, computing capacity, etc.

In this research, three kinds of grouping techniques are investigated to make the large-scale inventory system “easier” to manage. The first grouping technique is a network based ABC classification method. A new classification criterion is developed so that the inventory network characteristics are included in the classification process, and this criterion …

Evaluation Of A Supervisor Training Program For Odot’S Ecodrive Program, Donald M. Truxillo, John Macarthur, Leslie B. Hammer, Talya N. Bauer

TREC Final Reports

Eco-driving consists of using energy-efficient approaches to driving aimed at reducing fuel consumption and, ultimately, CO2 emissions. A previous study found that an EcoDrive informational campaign was effective at increasing the use of eco-driving behaviors, but only when employees perceived that their supervisor supported the program and when they were personally motivated to perform the eco-driving behaviors. In order to build upon the findings of our previous study, the present study focused on increasing the use of eco-driving behaviors through an informational eco-driving campaign combined with supervisor training to support the use of eco-driving practices.

In this study we collected …

Building Exposure Study In The State Of Florida And Application To The Florida Public Hurricane Loss Model, Joshua Michalski

Theses and Dissertations

Modeling hurricane events with models such as the Florida Public Hurricane Loss Model (FPHLM) is essential for insurance and reinsurance companies to estimate projected losses. Additionally, the models can be used by public officials to estimate and mitigate damages while also developing public safety policies to reduce the amount of damage and loss of life during a catastrophic event. The FPHLM combines hurricane event simulation and building vulnerability models to predict insurance portfolios losses. Before vulnerability functions are applied to insurance portfolios to determine total losses, these functions are weighted based upon building characteristics statistics representative of a given building …

An Examination Of How Ratings Of Airlines Are Effected By Different Types Of Information: A Mediation Analysis, Abdullah Selim Ozyurek

Theses and Dissertations

Many dynamics directly or indirectly influence the decision-making process. An individual’s demographic features, such as gender, country of origin, and emotions are some of the dynamics. In the aviation domain, air passengers purchase their air travel tickets under those dynamics. The purpose of this study was to determine if the airline type, gender of participants, and participants’ country of origin had an effect on ratings of an individual’s perception of safety and willingness to fly, and which emotions had a mediating effect on this relationship. The study included Lufthansa Airlines and Turkish Airlines from Europe. The affect was the participants’ …

Recognition Of Infrastructure Events Using Principal Component Analysis, Lane David Broadbent

Theses and Dissertations

Information Technology systems generate system log messages to allow for the monitoring of the system. In increasingly large and complex systems the volume of log data can overwhelm the analysts tasked with monitoring these systems. A system was developed that utilizes Principal Component Analysis to assist the analyst in the characterization of system health and events. Once trained, the system was able to accurately identify a state of heavy load on a device with a low false positive rate. The system was also able to accurately identify an error condition when trained on a single event. The method employed is …

The Feasibility Of Using A Markerless Motion Capture Sensor (Leap MotionTm Controller) Forquantitative Motor Assessment Intended For A Clinical Setting, Clay Jordan Kincaid

Theses and Dissertations

Although upper limb motor impairments are common, the primary tools for assessing and tracking these impairments in a clinical setting are subjective, qualitative rating scales that lack resolution and repeatability. Markerless motion capture technology has the potential to greatly improve clinical assessment by providing quick, low-cost, and accurate tools to objectively quantify motor deficits. Here we lay some of the groundwork necessary to enable markerless motion capture systems to be used in clinical settings. First, we adapted five motor tests common in clinical assessments so they can be administered via markerless motion capture. We implemented these modified tests using a …

A Study To Develop An Electronics Chassis Compound Cylinder Pressure Vessel Using Finite Element Modeling, Gordon Randall Straley

Theses and Dissertations

This thesis develops a process to design and analyze a two-layer compound cylinder pressure vessel utilizing an inner insert to house electronic circuit card assemblies. The process begins with sizing and analysis of a compound cylinder based on analytical formulas and progresses in complexity to a 2-Dimensional plane stress finite element model of the chassis assembly and ends with a computationally expensive 3-Dimensional finite element analysis of the pressure vessel. Comparing the results from the compound cylinder to the electronics chassis, it is observed that the inner insert geometry has a strong influence on the interfacial pressure at the upper …

Time Series Classification Using Covariance Descriptors, Oluwaseun Winsala

Theses and Dissertations

This thesis presents a novel framework for time series classification that leverages the geometric structure of covariance matrices when labeling signals. Our method maps each signal to a new multivariate localized feature signal (MLFS) representation, from which we compute a covariance descriptor. This robust MLFS covarieance representation handles classification tasks where the sampling rates of the signals vary within a class or classes. We demonstrate that by simply using the k-nearest neighbor classification rule and multiclass kernel support vector machine with the Riemannian metric between the MLFS convariance matrices, which produces state-of-the-art results on a number of standard datasets. Moreover, …

Numerical Study Of Erosion Of The Internal Wall Of Sales Gas Piping By Black Powder Particles, Ahmed Saud Al-Haidari

Theses and Dissertations

Micro particles, primarily from iron, can wreak havoc on a Sales Gas System. For example, the transport of particles with the gas flow can cause erosion damage to the piping system, lead to the release of toxic gasses, and interrupt the operation. The objective of the current work is to examine the erosion rate (ER) in an existing Sales Gas Piping System by simulating different black powder particles sizes and considering variable operation conditions. An elbow-shaped pipe spool is used to determine the area of maximum destruction. It will help the designer, engineer and operation personnel to predict the ER …

Investigating And Improving Bridge Management System Methodologies Under Uncertainty, Minwoo Chang

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

This dissertation presents a novel procedure to select explanatory variables, without the influence of human bias, for deterioration model development using National Bridge Inventory (NBI) data. Using NBI information, including geometric data and climate information, candidate explanatory variables can be converted into normalized numeric values and analyzed prior to the development of deterministic or stochastic deterioration models. The prevailing approach for explanatory variable selection is to use expert opinion solicited from experienced engineers. This may introduce human influenced biases into the deterioration modeling process. A framework using Least Absolute Shrinkage and Selection Operator (LASSO) penalized regression and covariance analysis are …