Engineering Commons^™

In Situ Tem Characterization Of Microstructure Evolution And Mechanical Behavior Of The 3d-Printed Inconel 718 Exposed To High Temperature, Supriya Koul, Le Zhou, Omar Ahmed, Yongho Sohn, Tengfei Jiang, Akihiro Kushima

Mechanical Engineering Faculty Research and Publications

This in situ transmission electron microscopy work presents a nanoscale characterization of the microstructural evolution in 3D-printed Inconel 718 (IN718) while exposed to elevated temperature and an associated change in the mechanical property under tensile loading. Here, we utilized a specially designed specimen shape that enables tensile testing of nano-sized thin films without off-plane deformations. Additionally, it allows a seamless transition from the in situ heating to tensile experiment using the same specimen, which enables a direct correlation of the microstructure and the mechanical property of the sample. The method was successfully used to observe the residual stress relaxation and …

Composition-Dependent Solidification Cracking Of Aluminum-Silicon Alloys During Laser Powder Bed Fusion, Holden Hyer, Le Zhou, Abhishek Mehta, Sharon Park, Thinh Huynh, Shutao Song, Yuanli Bai, Kyu Cho, Brandon Mcwilliams, Yongho Sohn

Mechanical Engineering Faculty Research and Publications

Consistent manufacturing of volumetrically dense engineering components, free of solidification cracks by laser powder bed fusion (LPBF), has been demonstrated for Al-Si alloys such as AlSi10Mg and Al12Si. The success in LPBF of these alloys is attributed to the near eutectic composition with a small freezing range. To illuminate this observation, cracking susceptibility was examined from Scheil-Gulliver solidification modeling by calculating the hot cracking susceptibility, |dT/df_S^1/2|. To validate the findings from hot cracking susceptibility calculations, six binary Al-Si alloys, whose compositions were strategically chosen at hypo-, near-, and hyper-eutectic compositions, were gas atomized into alloy powders, and …

Design Of An Ultra-Wideband Frequency-Modulated Continuous Wave Short Range Radar System For Extending Independent Living, Toai-Chi Nguyen

Master's Theses

Falls in the disabled and elderly people have been a cause of concern as they can be immobilized by the fall and have no way to contact others and seek assistance. The proposed frequency modulated continuous wave (FMCW) short range radar (SRR) system, which uses ultra-wideband (UWB) signals can provide immediate assistance by monitoring and detecting fall events. The unique characteristics of this system allow for a frequency-based modulation system to carry out triangulation and sense the location of the fall through the usage of a continuous chirp signal that linearly sweeps frequency. This project focuses on the development, design …

The Design Of Dynamic Probabilistic Caching With Time-Varying Content Popularity, Jie Gao, Shan Zhang, Lian Zhao, Xuemin Shen

Electrical and Computer Engineering Faculty Research and Publications

In this paper, we design dynamic probabilistic caching for the scenario when the instantaneous content popularity may vary with time while it is possible to predict the average content popularity over a time window. Based on the average content popularity, optimal content caching probabilities can be found, e.g., from solving optimization problems, and existing results in the literature can implement the optimal caching probabilities via static content placement. The objective of this work is to design dynamic probabilistic caching that: i) converge (in distribution) to the optimal content caching probabilities under time-invariant content popularity, and ii) adapt to the time-varying …

Measurements And Analysis Of Propagation Channels In Vehicle-To-Infrastructure Scenarios, Wei Li, Xiaoya Hu, Jie Gao, Lian Zhao, Xuemin Shen

Electrical and Computer Engineering Faculty Research and Publications

In this paper, we present measurements and analysis of propagation channels in vehicle-to-infrastructure (V2I) scenarios, which are the basis of designing vehicular communication systems. Firstly, we propose a deterministic geometry-based method to classify V2I links into three types, i.e., line-of-sight beneath (LOS-B), non-LOS (NLOS), and line-of-sight above (LOS-A), based on the environmental features, where roadside row of trees constitute the main obstacles. Secondly, for each link, we investigate the large-scale fading effect on V2I channels, including the path loss exponent and shadowing components. Subsequently, we validate the empirical path loss model using extensive measurements and two classical channel models. The …

Ambient And Indoor Pm10 And Pm10-Bound Pahs Around The Vicinity Of An Industrial Estate In Rayong, Thailand: Concentration And Source Identification, Navaporn Kanjanasiranont, Tassanee Prueksasit, Narut Sahanavin

Applied Environmental Research

The ambient and indoor air concentrations of PM10 and PM10-bound PAHs (16 priority PAHs) were investigated in Rayong Province, Thailand. The locations of the selected study areas were Map Ta Phut Industrial Estate and its vicinity comprising six sampling sites (four industrial areas and two vicinity areas). The indoor and ambient air samples of were collected in March 2017. The sampling sites located close to the road were detected the greatest ambient average concentrations of PM10, with an average value of 56.06 µg m-3 (Map Chalut Area or MC). The levels of indoor PM10 were mostly dependent on the resident …

Inspection And Understanding Of Sewer Network Condition In Dindaeng District (Thailand), Hnin E. Phyu, Sutha Khaodhiar

Applied Environmental Research

Sewer pipelines are usually operated with little maintenance after installation. After years in service, sewer pipes get old and deteriorated.  The present research is the first study that attempts to inspect the condition of sewer pipelines in the Bangkok Metropolitan Area. A robot with Closed Circuit Television (CCTV) was used to capture videos and images of the interior of the sewer pipelines between two manholes. The system was operated by Utility Business Alliance (UBA) Company. The condition of the sewer pipelines was visually analyzed in line with the scoring and grading system of New Zealand’s pipe inspection manual. CCTV footage …

Consequence Of Seawater Intrusion On Soil Properties In Agricultural Areas Of Nonthaburi Province, Thailand, Napaporn Phankamolsil, Kiattisak Sonsri, Yutthana Phankamolsil

Applied Environmental Research

Seawater intrusion associated with climate change and sea level rise (SLR) has been postulated for the last decade that causes negative impact on worldwide environmental resources. In Thailand, however; the information pertaining to its effect on soil properties in agricultural areas has not been clearly reported yet. Hence, this study aimed to investigate the seawater intrusion effect on soil properties in agricultural areas of Nonthaburi Province, Thailand. Five study locations, which anticipated to be affected by seawater intrusion, were selected based on the different distances from the Chao Phraya River. Soil morphological properties were recorded, besides undisturbed soil samples at …

Air Quality Indexing, Mapping And Principal Components Analysis Of Ambient Air Pollutants Around Farm Settlements Across Ogun State, Nigeria, Funmilola Oyebanji, Godson Ana, Opeyemi Tope-Ajayi, Adebayo Sadiq, Yahaya Mijinyawa

Applied Environmental Research

The focus of this study was to portray the spatial pattern of air quality across seasons in the eight sampled farm settlements using air quality indexes and assess the clusters of monitored air pollutants. The concentrations of air pollutants were determined using in-situ portable gas detectors and particulate counter. The AQI for each criteria pollutants (CO, O3, TSP, PM10, SO2, and PM2.5) was calculated using AQI formulae of the United States Environmental Protection Agency and mapped using the Inverse distance weighting (IDW) interpolation method in the Geographic information systems (GIS) environment. Principal component analysis (PCA) was used to group the …

Treatment Of Iron From Groundwater By Ozonation: Influence Of Hardness As A Scavenger, Apiradee Sukmilin, Ratsamee Sangsirimongkolying

Applied Environmental Research

This study assesses the efficiency of using ozone technology to treat iron from groundwater while hardness acts as a radical scavenger. Batch experiments were conducted to determine the effects of initial pH 6, 7 and 8, and hardness of 300, 400 and 500 mg L-1 and kinetic analysis. The optimum conditions were found to be initial pH of 8 and hardness of 300 mg L-1. The removal efficiency of iron by ozonation was 99.97%, which was higher than that of air without ozone applied (83.67%). However, the presence of hardness and tert-butanol (TBA) had a negative effect on the …

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 …

Gradient-Based Tradeoff Design For Engineering Applications, Lena Alexis Royster

Mechanical & Aerospace Engineering Theses & Dissertations

This research presents a formal method for gradient based tradeoff design including methods that extend to cases with singularities and cases with more performance characteristics then design variables. The goal is to find revised design variables that can achieve the targeted performance characteristics and remove any violations to the constraint functions. The tradeoff design problem is formulation in the framework of the Sequential Quadratic Programming and is solved using the gradient based method. The optimal solution is the search direction, s, which represents the most effective way to reduce the current objective and correct the current violation. In this research …

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 …

Recovery Effects On The Performance Of Athletic Shoes, Erich B. Hagen

Masters Theses

The materials used in running shoe midsoles are viscoelastic. Following a training session, a period of rest is required for the midsoles to undergo shape recovery and regain their energy absorption capability. It is common to think that a shoe will need two days of rest following a run to be adequately recovered in order to minimize the risk of running related injury and to maximize shoe performance while also maximizing the useful life of the shoe. Mechanical aging studies were done to investigate the effects of intermittent recovery periods on performance of an athletic shoe, the Nike Pegasus Turbo …