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2022

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Articles 91 - 120 of 262

Full-Text Articles in Environmental Engineering

Wind Flow Characteristics Of Multi-Vortex Tornadoes And Their Wind Effects On Residential Houses, Yi Zhao Aug 2022

Wind Flow Characteristics Of Multi-Vortex Tornadoes And Their Wind Effects On Residential Houses, Yi Zhao

Doctoral Dissertations

"Tornadoes strike the USA very frequently, with an average of 1200 reports per year, and the average annual tornado-induced property loss has reached $10B. The devastation from recent tornadoes have prompted a renewed interest in better understanding tornado dynamics, their interactions with the built environment, and the performance of civil structures during tornadoes. In the past, the wind effects caused by single-vortex tornadoes have been widely studied, while the multi-vortex tornadoes were rarely considered. In fact, many previous deadly, costly tornadoes involved multiple vortices. Therefore, it is important to understand the wind flow characteristics of multi-vortex tornadoes in order to …


Fabrication Of Lab-Scale Polymeric And Silicon Dioxide Nanoparticle-Enabled Thin Film Composite Reverse Osmosis Membranes For Potable Reuse Applications, Timothy J. Dinh Aug 2022

Fabrication Of Lab-Scale Polymeric And Silicon Dioxide Nanoparticle-Enabled Thin Film Composite Reverse Osmosis Membranes For Potable Reuse Applications, Timothy J. Dinh

Master's Theses

Reverse osmosis (RO) is widely used for water reclamation and is one of the most feasible technologies for addressing water scarcity around the world. RO membrane fabrication procedures are continually being optimized and modified to enhance the treatment performance and efficacy of the RO process. A review of the existing literature published on membrane fabrication revealed that a detailed and reproducible methodology consistent among prior studies was not available. Therefore, the primary objective of this study was to utilize techniques from prior research to develop a reliable lab-scale membrane fabrication process for studying the potable reuse applications of TFC RO …


Efficiency Of Bank Filtration In The Removal Of Cyanotoxins Under Different Levels Of Nutrients, Luke Walkenhorst Jul 2022

Efficiency Of Bank Filtration In The Removal Of Cyanotoxins Under Different Levels Of Nutrients, Luke Walkenhorst

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

Harmful Algal Blooms (HABs) are an increasing concern not only in Nebraska, but across the world. Increasing global temperatures in conjunction with overuse of synthetic fertilizers are leading causes to the increasing frequency and concern of HABs. In the present work, the effectiveness of simulated bank filtration (BF), as an economical water treatment option, to remove cyanotoxins under different levels of nutrients (nitrates and phosphates) was investigated. Vertical flow-through columns pre-acclimated with two levels of nutrients (e.g., nitrate and phosphate—10 vs. 50 mg/L) were exposed to two different levels of cyanotoxins (10 vs. 75 μg/L). Results from the study confirmed …


Ds-Menet For The Classification Of Citrus Disease, Xuyao Liu, Yaowen Hu, Guoxiong Zhou, Weiwei Cai, Mingfang He, Jialei Zhan, Yahui Hu, Liujun Li Jul 2022

Ds-Menet For The Classification Of Citrus Disease, Xuyao Liu, Yaowen Hu, Guoxiong Zhou, Weiwei Cai, Mingfang He, Jialei Zhan, Yahui Hu, Liujun Li

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

Affected by various environmental factors, citrus will frequently suffer from diseases during the growth process, which has brought huge obstacles to the development of agriculture. This paper proposes a new method for identifying and classifying citrus diseases. Firstly, this paper designs an image enhancement method based on the MSRCR algorithm and homomorphic filtering algorithm optimized by Laplacian (HFLF-MS) to highlight the disease characteristics of citrus. Secondly, we designed a new neural network DS-MENet based on the DenseNet-121 backbone structure. In DS-MENet, the regular convolution in Dense Block is replaced with depthwise separable convolution, which reduces the network parameters. The ReMish …


Construction And Operation Of A Pilot-Scale Odor Control Device, Brendan Bunker Jul 2022

Construction And Operation Of A Pilot-Scale Odor Control Device, Brendan Bunker

Department of Environmental Engineering: Theses and Other Student Research

Hydrogen sulfide (H2S) is a naturally occurring by-product of anaerobic digestion and causes an odor that can be a nuisance and a public health risk at higher concentrations. This compound can be treated through various means, but one of particular interest is a biotrickling filter (BTF). Such devices have excellent H2S treatment efficiencies, but start-up costs can be steep. The primary goal of this study is to explain the design and operation of a low-cost odor control device for improving environmental air quality in Nebraska using a BTF. This device has the potential for application as …


Wetland Soil Development Along Salinity And Hydrogeomorphic Gradients In Active And Inactive Deltaic Basins Of Coastal Louisiana, Amanda Fontenot Jul 2022

Wetland Soil Development Along Salinity And Hydrogeomorphic Gradients In Active And Inactive Deltaic Basins Of Coastal Louisiana, Amanda Fontenot

LSU Master's Theses

Coastal wetlands provide an abundance of ecosystem services that benefit society, such as essential habitat for commercial species, storm protection, nutrient cycling, and carbon storage. Louisiana faces rapid rates of relative sea level rise (natural subsidence and eustatic sea levels) that threaten wetland survival, which are amplified by a reduction of riverine sediment input. An important determining factor of marsh survival is the formation of wetland platform elevation, known as vertical accretion, which is determined by several processes including sediment deposition & erosion, below ground biomass (BGB) productivity, decomposition of organic matter, shallow & deep subsidence, and soil compaction. Feldspar …


Development An Edge-Computing Sensing Unit For Continuous Measurement Of Canopy Cover Percentage Of Dry Edible Beans, Wei-Zhen Liang, Joseph Oboamah, Xin Qiao, Yufeng Ge, Robert M. Harveson, Daran R. Rudnick, Jun Wang, Haishun Yang, Angie Gradiz Jul 2022

Development An Edge-Computing Sensing Unit For Continuous Measurement Of Canopy Cover Percentage Of Dry Edible Beans, Wei-Zhen Liang, Joseph Oboamah, Xin Qiao, Yufeng Ge, Robert M. Harveson, Daran R. Rudnick, Jun Wang, Haishun Yang, Angie Gradiz

Department of Agricultural and Biological Systems Engineering: Faculty Publications

Canopy cover (CC) is an important indicator for crop development. Currently, CC can be estimated indirectly by measuring leaf area index (LAI), using commercially available hand-held meters. However, it does not capture the dynamics of CC. Continuous CC monitoring is essential for dry edible beans production since it can affect crop water use, weed, and disease control. It also helps growers to closely monitor “yellowness”, or senescence of dry beans to decide proper irrigation cutoff to allow the crop to dry down for harvest. The goal of this study was to develop a device – CanopyCAM, containing software and hardware …


Effect Of Bromoform And Linseed Oil On Greenhouse Gas Emissions From Stored Beef Manure, Andrew Ortiz Balsero, Mara Zelt, Amy Millmier Schmidt, Miguel Fudolig, Daniel N. Miller Jul 2022

Effect Of Bromoform And Linseed Oil On Greenhouse Gas Emissions From Stored Beef Manure, Andrew Ortiz Balsero, Mara Zelt, Amy Millmier Schmidt, Miguel Fudolig, Daniel N. Miller

Department of Agricultural and Biological Systems Engineering: Faculty Publications

Emissions of carbon dioxide, methane, and nitrous oxide – potent greenhouse gases - from stored beef feedlot manure are a significant concern relative to climate change. Research on methane reduction strategies for enteric emissions has identified the application of organic additives, such as bromoform and linseed oil, to ruminant diets as potential solutions for reducing enteric emissions and pathogenic bacteria in excreted manure. The objective of this study was to determine the effect of bromoform and linseed oil on greenhouse gas emissions from beef feedlot manure, and on E. coli concentration in beef cattle manure, during a 5-week storage period. …


Elemental Sulfur And Metal Sulfide Minerals For Autotrophic Denitrification: Applications To Aquaculture, Groundwater Treatment, And Domestic Wastewater Treatment, Erica Amah Dasi Jul 2022

Elemental Sulfur And Metal Sulfide Minerals For Autotrophic Denitrification: Applications To Aquaculture, Groundwater Treatment, And Domestic Wastewater Treatment, Erica Amah Dasi

USF Tampa Graduate Theses and Dissertations

Nutrient pollution of waterways, from excess N and P, is a global concern that results in harmful impacts the environment, human health, and aquatic animals. This dissertation harnesses sulfur autotrophic denitrification to remove nutrients from groundwater, domestic wastewater, and wastewaters produced from marine recirculating aquaculture systems (RAS). Part 1 evaluates the denitrification performance of woodchips and elemental sulfur in cyclic denitrification filters (WS-CDFs) integrated into marine RAS operated under saline conditions. Part 2 investigates the use of metal sulfide minerals, with and without oyster shells, for supporting nutrient removal from groundwater in batch reactors. Part 3 assesses …


Learning From Machines: Insights In Forest Transpiration Using Machine Learning Methods, Morgan Thornwell Jul 2022

Learning From Machines: Insights In Forest Transpiration Using Machine Learning Methods, Morgan Thornwell

Dissertations and Theses

Machine learning has been used as a tool to model transpiration for individual sites, but few models are capable of generalizing to new locations without calibration to site data. Using the global SAPFLUXNET database, 95 tree sap flow data sites were grouped using three clustering strategies: by biome, by tree functional type, and through use of a k-means unsupervised clustering algorithm. Two supervised machine learning algorithms, a random forest algorithm and a neural network algorithm, were used to build machine learning models that predicted transpiration for each cluster. The performance and feature importance in each model were analyzed and compared …


Mdam-Drnet: Dual Channel Residual Network With Multi-Directional Attention Mechanism In Strawberry Leaf Diseases Detection, Tingjing Liao, Ruoli Yang, Peirui Zhao, Wenhua Zhou, Mingfang He, Liujun Li Jul 2022

Mdam-Drnet: Dual Channel Residual Network With Multi-Directional Attention Mechanism In Strawberry Leaf Diseases Detection, Tingjing Liao, Ruoli Yang, Peirui Zhao, Wenhua Zhou, Mingfang He, Liujun Li

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

The growth of strawberry plants is affected by a variety of strawberry leaf diseases. Yet, due to the complexity of these diseases' spots in terms of color and texture, their manual identification requires much time and energy. Developing a more efficient identification method could be imperative for improving the yield and quality of strawberry crops. To that end, here we proposed a detection framework for strawberry leaf diseases based on a dual-channel residual network with a multi-directional attention mechanism (MDAM-DRNet). (1) In order to fully extract the color features from images of diseased strawberry leaves, this paper constructed a color …


Investigating The Proper Use Of Litani River Basin Based On Water Quality, Mohamad Diab, Mohamad Soliman Jun 2022

Investigating The Proper Use Of Litani River Basin Based On Water Quality, Mohamad Diab, Mohamad Soliman

BAU Journal - Science and Technology

Litani River Basin (LRB) with a 170km length and annual river flow of 750 MCM is considered the most important water resource in Lebanon. Unfortunately, the river is facing water contamination as a result of human practices. Water Quality assessments was performed in the Litani River Basin using a combination of Principal Component Analysis method (PCA) and Water Quality Index method (WQI). Results revealed the improvement of the water quality significantly after passing lake Qaraoun. Moreover, according to WQI, Lower LRB water is ranked ‘’Good’’ for irrigation and ‘’BAD’ for drinking purposes. Microbial contamination is found to be the key …


Mechanical And Durability Properties Of Geopolymer Concrete – A Review, Lelian Elkhatib, Fadi Al Aridi, Adel Elkordi, Jamal Khatib Jun 2022

Mechanical And Durability Properties Of Geopolymer Concrete – A Review, Lelian Elkhatib, Fadi Al Aridi, Adel Elkordi, Jamal Khatib

BAU Journal - Science and Technology

Owing to the ongoing increase in human population, there is a need for more construction projects including residential buildings and other amenities. Concrete is by far the dominant material used in construction and cement is a main ingredient. Cement manufacture is an energy intensive process and emit large amounts of carbon dioxide into the atmosphere. A reduction in the amount of cement used in construction is greatly beneficial. The use of geopolymer or alkali activated materials can serve this purpose as it attempts to totally replace cement in concrete. Geopolymers are materials that consist mainly of silica and alumina materials …


Modified Biosand Filtration Using Aluminum Hydroxide Filter Media To Enhance Fluoride Removal, Joshelyn Guimaray Jun 2022

Modified Biosand Filtration Using Aluminum Hydroxide Filter Media To Enhance Fluoride Removal, Joshelyn Guimaray

USF Tampa Graduate Theses and Dissertations

There are over 20 countries whose citizens consume groundwater containing high levels of fluoride, including Nigeria, Mexico, India, China, and Ghana, which all have major health crises when it comes to the safety of their drinking water. Minerals like fluorite contain fluoride which is often found in groundwater aquifers. The minerals release fluoride into the groundwater. Per the World Health Organization (WHO) standard, the maximum contaminant limit for fluoride consumption should be less than 1.5 mg/L. Chronic exposure of elevated levels of fluoride can cause people to suffer debilitating health effects, such as dental and skeletal fluorosis. Dental fluorosis causes …


A Convergent Approach To Aqueous Lead (Pb) Mitigation Of A Supplemental Self-Supply Shallow Groundwater Source Accessed By Handpumps In Madagascar, Adaline Marie Buerck Jun 2022

A Convergent Approach To Aqueous Lead (Pb) Mitigation Of A Supplemental Self-Supply Shallow Groundwater Source Accessed By Handpumps In Madagascar, Adaline Marie Buerck

USF Tampa Graduate Theses and Dissertations

The World Health Organization (WHO) has consistently listed lead (Pb) as one of the ten chemicals of major public health concern. Though the toxic nature of lead has been known since the 20th century it is still utilized in a wide variety of products due to its favorable properties. Exposure to lead still accounts for approximately 900,000 deaths annually and disproportionately impacts those in low- and middle-income countries (LMIC) due to a variety of reasons such as poverty, malnutrition, and lack of knowledge on the toxic nature of lead. Lead exposure routes include air, soil, dust, diet, and water. Though …


Fragmentation Of Chemically Herded Oil Slicks By Obstacles: Visualizations, Flow Measurements, And Spatial Distributions, Ali Alshamrani Jun 2022

Fragmentation Of Chemically Herded Oil Slicks By Obstacles: Visualizations, Flow Measurements, And Spatial Distributions, Ali Alshamrani

USF Tampa Graduate Theses and Dissertations

Chemical herders are a promising technique for treatment of oil spills in icy waters at high latitudes. However, obstacles on the water surface such as floating ice affects or interferes with all spill response countermeasures including chemical herder operations by fracturing the contracting oil slick and trapping small oil patches. Chemical herders are likely to be especially useful in containing oil spills in remote, ice-infested Arctic waters, where using booms to contain an oil slick is difficult. Much of the previous research into chemical herder has focused on the effectiveness of different types of chemical herder agents to thicken oil …


Exploring Toluene Biosynthesis In Microbial Consortia Derived From Sediments And Superfund Site Groundwater, Raymond J. Poche Jun 2022

Exploring Toluene Biosynthesis In Microbial Consortia Derived From Sediments And Superfund Site Groundwater, Raymond J. Poche

LSU Master's Theses

While the aromatic hydrocarbon toluene is widely regarded as a contaminant associated with discharges of crude oil and refined petroleum products (e.g., gasoline), the enzyme phenylacetate decarboxylase catalyzes the decarboxylation of phenylacetate to yield toluene. Research described in this thesis further investigated toluene biosynthesis by a microbial consortium originating from chlorinated solvent-contaminated groundwater near Baton Rouge, Louisiana. In anoxic growth media supplemented with phenylacetate as a precursor, toluene accumulation was found to be maximal at near-neutral to slightly acidic pHs (toluene accumulation greater than 1 mg/L at pH in the range of 5.6 to 7.6, but was not observed for …


Evaluation Of Aluminum Dissolution, Current Density, And Pitting Patterns During Electrocoagulation, Monica Castro Carias Jun 2022

Evaluation Of Aluminum Dissolution, Current Density, And Pitting Patterns During Electrocoagulation, Monica Castro Carias

USF Tampa Graduate Theses and Dissertations

Electrocoagulation (EC) is a sustainable water treatment process involving the generation of coagulants on-site through the application of a voltage on metal (usually aluminum or iron alloys). The factors that impact EC system performance have been well researched, however further research is needed on the factors that impact anodic dissolution of aluminum electrodes, especially when the technology is transferred to full-scale applications. Electrode fouling is one of the factors that can impact dissolution of the anode during EC due to the formation of a protective oxide/hydroxide layer on the electrode surface. Previous studies have addressed electrode fouling by reversing polarity, …


Design And Commissioning Of An E-Beam Irradiation Beamline At The Upgraded Injector Test Facility At Jefferson Lab, Xi Li, Helmut Baumgart, Charles Bott, Gianluigi Ciovati, Shaun Gregory, Fay Hannon, Mike Mccaughan, Robert Pearce, Matthew Poelker, Hannes Vennekate, Shaoheng Wang Jun 2022

Design And Commissioning Of An E-Beam Irradiation Beamline At The Upgraded Injector Test Facility At Jefferson Lab, Xi Li, Helmut Baumgart, Charles Bott, Gianluigi Ciovati, Shaun Gregory, Fay Hannon, Mike Mccaughan, Robert Pearce, Matthew Poelker, Hannes Vennekate, Shaoheng Wang

Electrical & Computer Engineering Faculty Publications

The Upgraded Injector Test Facility (UITF) at Jefferson Lab is a continuous-wave superconducting linear accelerator capable of providing an electron beam with energy up to 10 MeV. A beamline for electron-beam irradiation has been designed, installed and successfully commissioned at this facility, aimed at the degradation study of 1,4-dioxane and per- and polyfluoroalkyl substances (PFAS) in wastewater treatment. A solenoid with a peak axial magnetic field of up to 0.28 T and a set of raster coils were used to obtain a Gaussian beam profile with a transverse standard deviation of ∼15.0 mm at the target location. Monte-Carlo simulations using …


Characterizing The Chemical And Microbial Fingerprint Of Unsheltered Homelessness In An Urban Watershed, Daniel Gerrity, Katerina Papp, Eric Dickenson, Meena Ejjada, Erica Marti, Oscar Quinones, Mayra Sarria, Kyle Thompson, Rebecca A. Trenholm Jun 2022

Characterizing The Chemical And Microbial Fingerprint Of Unsheltered Homelessness In An Urban Watershed, Daniel Gerrity, Katerina Papp, Eric Dickenson, Meena Ejjada, Erica Marti, Oscar Quinones, Mayra Sarria, Kyle Thompson, Rebecca A. Trenholm

Civil and Environmental Engineering and Construction Faculty Research

Unsheltered homelessness is rapidly becoming a critical issue in many cities worldwide. The worsening situation not only highlights the socioeconomic plight, but it also raises awareness of ancillary issues such as the potential implications for urban water quality. The objective of this study was to simultaneously leverage diverse source tracking tools to develop a chemical and microbial fingerprint describing the relative contribution of direct human inputs into Las Vegas' tributary washes. By evaluating a wide range of urban water matrices using general water quality parameters, fecal indicator bacteria (FIB), human-associated microbial markers [e.g., HF183, crAssphage, and pepper mild mottle virus …


Axial Hypersensitivity Is Associated With Aberrant Nerve Sprouting In A Novel Model Of Disc Degeneration In Female Sprague Dawley Rats, David J. Lillyman, Fei San Lee, Evie C. Barnett, Tyler J. Miller, Moreno Lozano Alvaro, Henry C. Drvol, Rebecca A. Wachs Jun 2022

Axial Hypersensitivity Is Associated With Aberrant Nerve Sprouting In A Novel Model Of Disc Degeneration In Female Sprague Dawley Rats, David J. Lillyman, Fei San Lee, Evie C. Barnett, Tyler J. Miller, Moreno Lozano Alvaro, Henry C. Drvol, Rebecca A. Wachs

Department of Agricultural and Biological Systems Engineering: Faculty Publications

Chronic low back pain is a global socioeconomic crisis and treatments are lacking in part due to inadequate models. Etiological research suggests that the predominant pathology associated with chronic low back pain is intervertebral disc degeneration. Various research teams have created rat models of disc degeneration, but the clinical translatability of these models has been limited by an absence of robust chronic painlike behavior. To address this deficit, disc degeneration was induced via an artificial annular tear in female Sprague Dawley rats. The subsequent degeneration, which was allowed to progress for 18-weeks, caused a drastic reduction in disc volume. Furthermore, …


Using Metal-Organic Frameworks (Mof) To Reduce The Carbon Footprint Of Concrete, Mona Ibrahim El-Hallak Jun 2022

Using Metal-Organic Frameworks (Mof) To Reduce The Carbon Footprint Of Concrete, Mona Ibrahim El-Hallak

Theses

The production of concrete by the construction industry has a massive impact on the environment. The process of manufacturing its main component, cement, releases a considerable amount of anthropogenic carbon dioxide. This thesis is concerned with the production of sustainable and eco-friendly concrete that integrates metal-organic frameworks (MOF) to capture and offset the CO2 emissions emitted during the production of cement. The main objective is to synthesize a MOF capable of capturing CO2 in concrete through accelerated carbonation curing and to assess its impact on concrete performance. Different parameters were examined, including the MOF content, initial curing duration, …


Numerical Modelling Of Externally-Bonded Fiber Reinforced Polymer Shear-Strengthened Reinforced Concrete Beams Subjected To Fatigue Loading, Nagwa Ibrahim Fares Jun 2022

Numerical Modelling Of Externally-Bonded Fiber Reinforced Polymer Shear-Strengthened Reinforced Concrete Beams Subjected To Fatigue Loading, Nagwa Ibrahim Fares

Theses

An extensive number of existing structures persistently exposed to fatigue loading such as bridges, offshore structures, pavements, and highways, are in urgent need of repairing and strengthening. This may be attributed to the continuous increase in the load requirements, change of the structure’s function, and meeting current load standards. Among the potential methods of rehabilitation and strengthening of existing reinforced concrete structures, the externally bonding fiber reinforced polymers (FRP) composites are gaining massive popularity and becoming a viable and cost-effective method. Shear failure of reinforced concrete (RC) beams is known to be brittle, which occurs without prior sufficient warnings; therefore, …


Understanding Ch4 Emissions From Compostables: An Exploration Of Local Ch4 Emissions From Landfilled Compostables And The Efficacy Of Emission Mitigation Via Anaerobic Biogas Digestion, Jordan-Yoosuf Aljbour Jun 2022

Understanding Ch4 Emissions From Compostables: An Exploration Of Local Ch4 Emissions From Landfilled Compostables And The Efficacy Of Emission Mitigation Via Anaerobic Biogas Digestion, Jordan-Yoosuf Aljbour

University Honors Theses

Methane (CH4) is the second most abundant anthropogenic greenhouse gas within the atmosphere, comprising ~16% of the total anthropogenic greenhouse gas composition on Earth. It has an ~12-year lifetime relative to its eventual oxidation via reaction with tropospheric hydroxyl radicals (OH), and has a 100-year indirect global warming potential (GWP) approximately ranging between 28-36 [Environmental Protection Agency, 2021]. In recent years, the observed average global concentration of atmospheric CH4 has increased by ~11.0% from 2020 (~15.3 ppb) to 2021 (~17.0 ppb) [Dlugokencky et al., 1994; National Oceanic and Atmospheric Administration, 2022]. With …


Effects Of Experimental Scale On The Adsorption Of Two Pharmaceutical Drugs Detected In Municipal Wastewater Effluent, Michael Moore Jun 2022

Effects Of Experimental Scale On The Adsorption Of Two Pharmaceutical Drugs Detected In Municipal Wastewater Effluent, Michael Moore

Master's Theses

Pharmaceutical drugs are being produced and consumed in increasing quantities every year and are poorly treated by conventional wastewater treatment processes, leading to increasing detection of such compounds in surface water, groundwater, and municipal drinking water. Soil aquifer treatment (SAT) is a promising method for treating these emerging compounds through combined adsorption and degradation of target compounds in soil. This thesis examines the consistency of results from typical studies like adsorption isotherms and soil columns utilized in analysis of SAT performance, across varying experimental scales. The adsorption behavior of two pharmaceuticals was investigated as a function of experimental scale and …


Understanding The Interfacial Processes Of Reactive Nanobubbles Toward Agricultural Applications, Xiaonan Shi May 2022

Understanding The Interfacial Processes Of Reactive Nanobubbles Toward Agricultural Applications, Xiaonan Shi

Dissertations

There is a growing interest in nanobubble (NB) technology because of its diverse applications (e.g., detergent-free cleaning, water aeration, ultra-sound imaging and intracellular drug delivery, and mineral processing). NBs have a higher efficiency of mass transfer compared to bulk scale bubbles due to the high specific surface areas. The high specific surface also facilitates physical adsorption and chemical reactions in the gas liquid interface. Furthermore, the collapse of NBs creates shock waves and the formation of hydroxyl radicals (OH).

However, it remains elusive why or how NBs are stabilized in water and particularly, the states of internal pressures of NBs …


Reactive Iron Mineral Coatings In Redox Transition Zones Of A Site With Historical Contamination: Abiotic Attenuation, Xin Yin May 2022

Reactive Iron Mineral Coatings In Redox Transition Zones Of A Site With Historical Contamination: Abiotic Attenuation, Xin Yin

Dissertations

Reactive iron mineral coatings are found throughout reduction-oxidation (redox) transition zones and play a significant role in contaminant transformation processes. In this study, an 18.3-meter core is collected, subsampled, and preserved under anoxic conditions to maintain its original redox state. Screening analyses are conducted at sampling increments of 5.08 cm in depth for the following: elemental concentrations with X-ray fluorescence (XRF), sediment pH, sediment oxidation-reduction potential (ORP), total volatile organic carbon (TVOC) in the sample headspace, and abundant bacteria (16S rRNA sequencing). Using the Fe and S gradients correlated with microbial data, five RTZs are delineated. To characterize iron mineral …


Hydrodynamic Limitations To Mangrove Seedling Retention In Subtropical Estuaries, Kelly M. Kibler, Christian Pilato, Linda Walters, Melinda Donnelly, Jyotismita Taye May 2022

Hydrodynamic Limitations To Mangrove Seedling Retention In Subtropical Estuaries, Kelly M. Kibler, Christian Pilato, Linda Walters, Melinda Donnelly, Jyotismita Taye

Flow-biota Interaction and Natural Infrastructure Design

Mangrove forest sustainability hinges upon propagule recruitment and seedling retention. This study evaluates biophysical limitations to mangrove seedling persistence by measuring anchoring force of two mangrove species (Rhizophora mangle and Avicennia germinans). Anchoring force was measured in 362 seedlings via lateral pull-tests administered in mangrove forests of two subtropical estuaries and in laboratory-based experiments. Removal mechanism varied with seedling age: newly-established seedlings failed due to root pull-out while seedlings older than 3 months failed by root breakage. Anchoring force of R. mangle seedlings was consistently and significantly greater than A. germinans (GLM: p = 0.002), however force to …


A Circular Economy Approach To Improve E-Waste Recycling In California: Economic Potential And Policy Options, Kripa Shah May 2022

A Circular Economy Approach To Improve E-Waste Recycling In California: Economic Potential And Policy Options, Kripa Shah

Master's Projects and Capstones

The higher consumption rates of electronic devices along with their short life cycles and few repair options poses a huge challenge for E-waste industries to manage them effectively. E-waste comprises of hazardous materials and toxic constituents that can affect the environment and public health through improper disposal. However, they also contain few valuable materials that, if recovered, can reduce the dependence on virgin raw materials. Circular economy has the potential to utilize these valuable materials and gain environment and socio-economic benefits. The research explains how the adoption of a circular economy approach can help improve the E-waste recycling in California …


A Segmentation-Guided Deep Learning Framework For Leaf Counting, Xijian Fan, Rui Zhou, Tardi Tjahjadi, Sruti Das Choudhury, Qiaolin Ye May 2022

A Segmentation-Guided Deep Learning Framework For Leaf Counting, Xijian Fan, Rui Zhou, Tardi Tjahjadi, Sruti Das Choudhury, Qiaolin Ye

Department of Agricultural and Biological Systems Engineering: Faculty Publications

Deep learning-based methods have recently provided a means to rapidly and effectively extract various plant traits due to their powerful ability to depict a plant image across a variety of species and growth conditions. In this study, we focus on dealing with two fundamental tasks in plant phenotyping, i.e., plant segmentation and leaf counting, and propose a two-steam deep learning framework for segmenting plants and counting leaves with various size and shape from two-dimensional plant images. In the first stream, a multi-scale segmentation model using spatial pyramid is developed to extract leaves with different size and shape, where the fine-grained …