Engineering Commons^™

Source And Distribution Of Polycyclic Aromatic Hydrocarbons (Pahs) In Surface Sediment From Chalong Bay, Phuket, Thailand, Danai Tipmanee, Yada Patchim, Penjai Sompongchaiyakul

Applied Environmental Research

This study aimed to investigate the spatial distribution and apportionment of potential sources of the 16 US-EPA priority PAHs in surface sediments of Chalong Bay, Phuket, Thailand. A total 28 of sediment samples were collected from areas with high maritime activity in Chalong Bay, subjected to conventional high recovery Soxhlet extraction, purified with SiO2 column chromatography, and quantified by Gas Chromatography-Mass Spectrometry (GC/MS). Total concentration of PAHs (Σ16PAHs) ranged from 31.15 to 1696 ng g−1 dry weight, with an average of 198.2 ± 318.5 ng g−1 dry weight. Binary diagnostic ratios plots were used to distinguish between petrogenic and pyrogenic …

Willingness To Pay For Improving Household Solid Waste Management In Vietnam, Phan C. Chinh, Nguyen T.Q. Hung, Nguyen M. Ky, Nguyen T.L. Ai, Nguyen M. Tam

Applied Environmental Research

Management of solid waste is a major challenge in urban areas of most parts of the world, especially in developing countries. The study aimed to determine and estimate the willingness to pay (WTP) of the selected households for the improvement of solid waste management in Vietnam. The research evaluated WTP of household solid waste in case studies in Bien Hoa and My Tho cities using contingent valuation method (CVM). The data were collected through a closed-ended questionnaire survey and interviews with 200 households. The results showed that the most willingness to pay was equal to 10,000 and 15,000 VND per …

Current Trends In Steroidal 17Α-Ethynylestradiol (Ee2) Removal From The Environment: A Review, Wasiu A. Abibu, Gafar Bamigbade, Amos O. Kolawole, Taiwo Ajayi, Abdul W. Sakariyau

Applied Environmental Research

Emerging contaminants have posed major environmental and health challenges to human and aquatic lives. They include pharmaceuticals, endocrine disrupting compounds (EDCs), persistent environmental pollutants and many more. EE2 is an example of an endocrine disrupting compounds (EDCs) increasingly gaining acceptance and used to augment the deficiencies of other reproductive hormones. EE2 constitutes environmental nuisance via discharge into aquatic bodies, thus, threatening aquatic lives and resulting in health defects in human. It is worthy of note that previous researchers have channeled their studies to identifying ways of expelling EE2 from the environment. However, they remain persistent in the environment. The current …

Impact Of Grain Morphology On The Temporal Evolution Of Interfacial Area During Multi-Phase Flow In Porous Media, Fizza Zahid

USF Tampa Graduate Theses and Dissertations

Many environmental issues deal with the movement of immiscible fluids in the subsurface, e.g., cleanup of oil spills and geological carbon dioxide sequestration. Engineers face a constant challenge to improve the efficiency of these processes. This can be facilitated by studying the underlying physics of how fluids flow and interact in these systems.

Traditionally, lab experiments can provide reliable information about fluid architecture in porous medium, such as trapped fluid volumes and contact area between two immiscible fluids (interfacial area). However, these methods can be expensive and tedious. A well designed numerical experiment is not only able to describe fluid …

Corrosion Rate Prediction In Frp-Concrete Repair, Mohammad A. Khawaja

USF Tampa Graduate Theses and Dissertations

Research has proven that wrapping structural elements with fiber-reinforced polymers (FRPs) slows down chloride-induced corrosion rate but does not stop it. Although FRP has been used for corrosion repair for over 40 years, predictive corrosion rate models for FRP-concrete systems are limited in literature. This dissertation presents an oxygen diffusion-based predictive framework to estimate corrosion rate in FRP-concrete systems.

The dissertation has three main components. First, a core framework that is referred to as Khawaja-Sen-Bhethanabotla (KSB) model. In the KSB model, statistical methods were used to extend experimental data on oxygen permeation coefficients. These data were for one and two …

Experimental Evaluation Of Drying Spent Nuclear Fuel For Dry Cask Storage Through Vacuum And Forced Helium Dehydration, Jonathan Ellis Perry

Theses and Dissertations

Currently approximately 80,000 tons of spent nuclear fuel (SNF) are in either dry or wet storage at nuclear power plants or designated spent fuel storage facilities. Over 2,000 tons are added to that sum each year. All SNF must be dried to an accepted Nuclear Regulatory Commission (NRC) drying criteria before being placed in dry storage. Inadequately drying SNF increases the risk of detrimental effects to the fuel while in dry storage. Two commonly used drying operations in the nuclear industry are vacuum drying and forced helium dehydration (FHD). Although these drying processes have been used for many years, there …

Age And Sex Dependency Of Thoracic Aortic Aneurysm Progression In A Mouse Model Of Marfan Syndrome, Nazli Gharraee

Theses and Dissertations

Aneurysm of the ascending aorta is the most common type of thoracic aortic aneurysm, and it is a life-threatening manifestation of Marfan syndrome (MFS), a connective tissue disorder caused by mutation of the FBN1 gene. Incidence of Marfan syndrome is similar for men and women; however, men suffer from more severe aortic events compared to women.

This study aims to provide a better understanding of age and sex dependency of cell and extracellular matrix alterations of the aortic wall during the progression of the aneurysm caused by Marfan syndrome. To achieve this goal, the C1041G/+ mouse model of Marfan syndrome …

Removal Of Heavy Metals Using Novel Adsorbent Materials, Lesley Joseph

Theses and Dissertations

Heavy metal contamination is a growing concern throughout the world, particularly as industrial and urban activities have increased. Inadequate water and wastewater treatment, coupled with increased industrial activity, have led to increased heavy metal contamination in rivers, lakes, and other water sources in developing countries. To address these concerns, a significant amount of research has been conducted on various novel adsorbents to evaluate their ability to remove heavy metals. Thus, in this study, MIL-100(Fe) and MIL-101(Cr) are fabricated and investigated to determine their ability to remove copper (Cu2+), cadmium (Cd2+), and lead (Pb2+) from aqueous solution. The experimental data fit …

Fate Of Nitrogen And Effectiveness Of Evaporation On Managing Leachate In Collection And Storage Ponds: A Case Study At The Three Rivers Solid Waste Authority Regional Landfill, Kaitlen Rose Drafts

Theses and Dissertations

Treatment of leachate from municipal solid waste (MSW) landfills can be complex and difficult, due to the variety of contaminants present. The purpose of this work was to evaluate the fate of nitrogen and effectiveness of leachate evaporation in a leachate storage and collection pond at the Three Rivers Solid Waste Authority (TRSWA) MSW landfill in Jackson, South Carolina. This was accomplished by determining the fate of nitrogen species in the pond, exploring effect of the site’s Lilypad droplet sprayer system on ammonia-nitrogen, and exploring potential to reduce overall quantity of leachate to be treated through evaporation from the pond. …

Deep Learning Based Sound Event Detection And Classification, Alireza Nasiri

Theses and Dissertations

Hearing sense has an important role in our daily lives. During the recent years, there has been many studies to transfer this capability to the computers. In this dissertation, we design and implement deep learning based algorithms to improve the ability of the computers in recognizing the different sound events.

In the first topic, we investigate sound event detection, which identifies the time boundaries of the sound events in addition to the type of the events. For sound event detection, we propose a new method, AudioMask, to benefit from the object-detection techniques in computer vision. In this method, we convert …

Removal Of Selected Organic Contaminants By Various (Nano) Adsorbent-Ultrafiltration Hybrid Systems, Sewoon Kim

Theses and Dissertations

Organic contaminants, which result from overuse and discharge of dyes, pharmaceutically active compounds, personal care products, and endocrine-disrupting compounds, have been received attention as contemporary water issues. However, conventional water and/or wastewater treatment system cannot sufficiently control for these contaminants for their stability and complexity. In this study, combined novel adsorbent with ultrafiltration (UF) hybrid system (termed ‘adsorbent-UF’) was applied to removal selected organic contaminants. UF with upstream adsorption has positive effects on performance in terms of the removal of selected organic contaminants, separating used adsorbents and reducing foulants. Activated biochar, metal organic frameworks, and Ti3C2TX MXene were used as …

Experimental Investigation Of Single And Two-Phase Heat Transfer Performance In Microchannels With Surface Modifications And Multiple Inlet Restrictors, Saad Kadham Oudah

Theses and Dissertations

Due to shrinking component sizes and faster switching speeds, the volumetric heat generation rates and surface heat flux in many advanced power electronic devices have increased exponentially, creating an urgent need for efficient cooling technologies. It has become particularly challenging to maintain an optimal temperature at the device level. Among advanced cooling techniques, single-phase and two-phase microchannel heat sinks show considerable promise in removing a significant amount of heat from a small surface area. Considered one of the most efficient heat dissipaters, the two-phase microchannel heat sink can handle very high heat flux at a small footprint and requires relatively …

Multimodal Robotic Health In Future Factories Through Iiot, Data Analytics, And Virtual Commissioning, Clint Saidy

Theses and Dissertations

The manufacturing sector is continuously reinventing itself by embracing opportunities offered by the industrial internet of things and big data, among other advances. Modern manufacturing platforms are defined by the quest for ever increasing automation along all aspects of the production cycle. Furthermore, in the next decades, research and industry are expected to develop a large variety of autonomous robots for a large variety of tasks and environments enabling future factories. This continuing pressure towards automation dictates that emergent technologies are leveraged in a manner that suits this purpose. These challenges can be addressed through the advanced methods such as …

Time-Domain Measurement Of Magnetization Dynamics In Ferrofluids, Brian Egenriether

Theses and Dissertations

Time-domain measurements are made on a magnetite-based (Fe3O4) ferrofluid using an inductive technique. The constituent particles are 5.8% by volume, polydisperse, and have a nominal diameter of 10nm with a ~1nm-thick anionic hydrophobic coating. The ferrofluid is placed in a sealed channel on a coplanar waveguide (CPW) situated in an adjustable external magnetic bias field. A fast-rising step current in the CPW quickly reorients the local magnetic field above the signal trace causing the particles’ moments to align in the new field configuration. This changing magnetization induces a voltage in the CPW that is detected by a sampling oscilloscope. Precessional …

Enhanced Flow Boiling And Bubble Dynamics With Hfe7100 & Di Water In Interconnected Microchannels, Jiaxuan Ma

Theses and Dissertations

Flow boiling in microchannels using dielectric fluids is one of the most desirable cooling solutions for high power electronics. Primary two-flow patterns, including bubbly flow, slug flow, and annular flow, have been well established in microchannels. However, it is challenging to promote flow boiling performance, particularly critical heat flux (CHF), due to their unfavorable thermophysical properties. Considering these situations, flow boiling in parallel and isolated microchannels have been extensively studied. In this dissertation, a novel concept that has five parallel microchannels (W=200 µm, H=250 µm, L=10 mm) are interconnected by micro-slots (20 µm wide and 250 µm deep) starting from …

Modeling Human-Structure Interaction Using Control System When Bouncing On Flexible Structure, Ahmed Tamween Baeewi Al-Zubaidi

Theses and Dissertations

High performance materials have enabled engineers to design civil structures with lower dead loads. However, lower dead loads result in a higher live-to-dead load ratio and the possibility of excessive vibrations due to human loading. Classical methods that have been used to study this human-structure interaction (HSI) model the person as a mass-spring-damper (MSD) system. While these models are often able to represent the dynamics of the system, the human body is a more complex, dynamic system. For example, MSD systems cannot add energy to the overall human-structure system; therefore, they do not allow for the incorporation of excitation that …

Vascular Endothelial Dysfunction And Effects On Arterial Wall Microstructure, Jeffrey Thomas Rodgers

Theses and Dissertations

Vascular endothelial cell dysfunction (ECD) is a disease characterized by the inability of the vascular endothelial cells to transmit signaling molecules, namely nitric oxide (NO), in response to changes in blood flow rate. This disease is shown to be incident in the onset of more severe vascular disease such as hypertension, atherosclerosis, and heart failure. Long-term ECD is shown to cause long-term remodeling such as decreased flow-mediated dilation, increased pulse-wave velocity, intimal-medial thickening, and increased wall stiffness due to collagen deposition. We used second harmonic generation (SHG) microscopy to analyze this change in the collagen microstructure of the arterial extracellular …

Real-Time Probabilistic Solvers For Digital Twins Of Power Electronic Systems, Matthew Aaron Milton

Theses and Dissertations

In recent years, switching power electronic systems for use in power conversion, generation, and distribution have become increasingly larger and complex in their design. With the increase in complexity comes the increase in difficulty in performing analysis, experiments, and health management on such systems in physical space. Part of this difficulty comes from challenge of access to and understanding of the internal interplay of the numerous components, safety and cost of system operation, and the inherent uncertainty of physical characteristics of systems and their environment.

A recent approach for testing and diagnostics/prognostics of power electronic systems is the application of …

Impact Of Particle Surface Charge Heterogeneity On Deposition Onto Flat Surfaces And Transport In Porous Media, Thompson Delon

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

Biological and non-biological natural colloids are anisotropic and ubiquitously exist in groundwater. Previously in colloid transport modelling, colloids are assumed to be homogenous for simplification, whether in shape or surface charge. More research has been done to incorporate surface heterogeneity in the transport experiment, i.e., surface charge heterogeneity on collector in column experiment. However, few studies have been done on surface heterogeneity on colloids themselves.

In this dissertation, Janus particles with different surface charge was developed to model surface heterogeneity on colloids. The interaction energy between Janus particle and flat surfaces was analyzed through DLVO simulation. It was discovered that …

In-Service Performance Evaluation And Installation Recommendations For Cable Median Barriers On Non-Continuously Shielded, Divided-Median Kansas Freeways, Nathan Dowler

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

The Kansas Department of Transportation (KDOT) installed 7.95 miles of cable median barrier (CMB) along K-10, K-96, and US-75 freeways in 2011 and 2012. In January 2020, KDOT funded a study to determine the in-service performance of its CMBs. In addition, KDOT sought to determine if it was cost-effective to modify guidelines for installing median barriers, which were based on annual daily traffic and median width.

Researchers reviewed every crash within approximately ¼ mile of a CMB installation and extracted crashes which involved a CMB impact. Researchers analyzed the critical details of each CMB crash, with particular emphasis on penetrations, …

Urban Consolidation Center Or Peer-To-Peer Platform? The Solution To Urban Last-Mile Delivery, Qiyuan Deng, Xin Fang, Yun Fong Lim

Research Collection Lee Kong Chian School Of Business

The growing population in cities and booming e-commerce activities create huge demand for urban last-mile delivery, exerting intense pressure on the cities' well-being. To keep congestion and pollution under control, a consolidator can operate an urban consolidation center (UCC) to bundle shipments from multiple carriers before the last-mile delivery. Alternatively, the consolidator can operate a peer-to-peer platform for the carriers to share delivery capacity. We provide guidance for the consolidator to choose between these two business models by comparative analysis. We capture the interactions between the consolidator and carriers using a game-theoretical framework. Under each business model, the consolidator first …

The Professional Constructor, Full Issue, Volume 46, Number 01

The Professional Constructor

No abstract provided.

Prediction Of Residual Stress And Distortion In Laser Powder Bed Fusion Additive Manufacturing, Bhanuprakash Sairam Kosaraju

Theses and Dissertations

Additive Manufacturing (AM) has its proven advantages to unlock the design space and manufacturing capabilities for complex geometries with lightweights. Distortion is one of the most common defects that occur in Laser Powder Bed Fusion Additive Manufacturing (LPBFAM), which is caused by the significant residual stress during the printing process. This can lead to numerous process iterations to achieve the requisite form and fit tolerances.

In this study, Finite Element (FE) model that utilizes the element birth approach was developed to predict the residual stress and distortion in the LPBFAM process. The methodology leverages a simplified approach where the detailed …

Grafting Based Thermoplastic-Thermoset Bonding For Aerospace Structures, Saurabh Vaidya

Theses and Dissertations

The use of carbon fiber composites is rapidly increasing in the aerospace industry. Fiber reinforced plastic composites can primarily be classified as thermoplastic and thermoset, both offer unique advantages over one another. Thermosets cure at relatively low temperature and in general, are lower priced than thermoplastic composites. However, the cost of autoclave for the curing of thermosets is a major drawback. On the other hand, thermoplastics are showing higher damage tolerance. They can be re-melted and re-consolidated and have the potential to be re-used / recycled. The repair of TP composites is not developed yet. Therefore, both the types attract …

Multi-Robot Coordination With Environmental Disturbances, Adem Coskun

Theses and Dissertations

Multi-robot systems are increasingly deployed in environments where they interact with humans. From the perspective of a robot, such interaction could be considered a disturbance that causes a well-planned trajectory to fail. This dissertation addresses the problem of multi-robot coordination in scenarios where the robots may experience unexpected delays in their movements.

Prior work by Čáp, Gregoire, and Frazzoli introduced a control law, called RMTRACK, which enables robots in such scenarios to execute pre-planned paths in spite of disturbances that affect the execution speed of each robot while guaranteeing that each robot can reach its goal without collisions and without …

Instrumentation And Experimentation Development For Robotic Systems, Tristan Kyzer

Theses and Dissertations

Localization of robotic systems is a necessity for control of robotic systems and often requires the use of costly sensors and equipment onboard the robot or installed within a facility. GPS or GNSS sensors are effective for localizing robots in GPSaccessible environments, but do not work as well in dense urban areas or inside fully enclosed buildings, such as factories or warehouses. Sensors such as LiDAR can be costly and require substantial experience and knowledge to utilize as well as potential changes to infrastructure for use. Computer vision-based localization systems offer potential as a localization solution for various applications. A …

Nondestructive Evaluation And Structural Health Monitoring Of Manufacturing Flaws And Operational Damage In Composite Structures, Robin James

Theses and Dissertations

Advanced composite materials have begun to be used extensively in the manufacturing of aerospace structures. Composite aerospace structures can develop complex types of damages during the manufacturing stages and operational lifetime. This creates an indispensable demand for appropriate nondestructive evaluation (NDE) and structural health monitoring (SHM) methods that are tailored to specific types of damage. This dissertation addresses innovative methods for NDE and SHM of manufacturing flaws and operational damage in composite structures.

For the NDE of manufacturing flaws in carbon fiber reinforced polymer (CFRP) composites, an eddy current testing (ECT) NDE method has been developed by conducting multiphysics modeling …

Rehabilitation Of Timber Piles Using Fiber Reinforced Polymers Analyzed With Acoustic Emission, Rebekah Marie Krol

Theses and Dissertations

Assessing the current state of infrastructure and implementing strengthening or rehabilitation methods on old or damaged members is important to ensure safety and longevity of structures. Non-destructive testing is an important tool for localizing and characterizing damage in structures, especially structures that are more susceptible to damage because of age or environment. In addition to locating inadequate members, it is essential to have a repair technique in place so that the structure can continue to be used in a safe manner.

This study aims to review the use of acoustic emission for evaluating damage obtained in timber piles subjected to …

Role Of Ahr Ligands In Immune Modulation To Suppress Inflammation Through The Regulation Of Microrna And Gut Microbiome, Osama Azeldeen Abdulla

Theses and Dissertations

The aryl hydrocarbon receptor (AhR) is a ligand-activated transcription factor and an environmental sensor that is highly conserved evolutionarily. It was first discovered in the early 1970s for its ability to bind with high affinity to 2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD), an environmental pollutant and induce a xenobiotic-metabolizing enzyme known as aryl hydrocarbon hydroxylase (AHH). AhR was shown to regulate TCDD-mediated toxicity against a variety of tissues including the immune system. More recently, AhR has been characterized as key regulator of the immune system, specifically the differentiation of T cells. Also, several AhR ligands have been characterized in addition to TCDD such as …

Temperature Dependence Of Electroluminescence And Current-Voltage Characteristics Of Arrays Of Deep Ultraviolet Algan Micropixel Led, Dhruvinkumar Prakashchandra Patel

Theses and Dissertations

III-Nitride based deep ultraviolet (DUV) light emitting diodes are non-toxic light sources that are highly desirable to replace current mercury lamp-based technology for air and water purification, surface and object disinfection, and sterilization. In the present. By freezing out defect related conduction pathways at temperatures less than 50K, the external quantum efficiency (EQE) of an interconnected array of 1,296 AlGaN DUV micropixels is improved by 4 times, underscoring the importance of defect management. Assuming a current injection efficiency (CIE) of 100% and considering that the light extraction efficiency (LEE) is constant with temperature, the 4-fold increase in the EL signal …