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2020

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Articles 1531 - 1560 of 1829

Full-Text Articles in Civil and Environmental Engineering

Storm Tide Amplification And Habitat Changes Due To Urbanization Of A Lagoonal Estuary, Philip Orton, Eric W. Sanderson, Stefan Talke, Mario Giampieri, Kytt Macmanus Jan 2020

Storm Tide Amplification And Habitat Changes Due To Urbanization Of A Lagoonal Estuary, Philip Orton, Eric W. Sanderson, Stefan Talke, Mario Giampieri, Kytt Macmanus

Civil and Environmental Engineering Faculty Publications and Presentations

In recent centuries, human activities have greatly modified the geomorphology of coastal regions. However, studies of historical and possible future changes in coastal flood extremes typically ignore the influence of geomorphic change. Here, we quantify the influence of 20th-century man-made changes to Jamaica Bay, New York City, on present-day storm tides. We develop and validate a hydrodynamic model for the 1870s based on detailed maps of bathymetry, seabed characteristics, topography, and tide observations for use alongside a present-day model. Predominantly through dredging, landfill, and inlet stabilization, the average water depth of the bay increased from 1.7 to 4.5 m, tidal …

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Accessibility And Equity Analysis Of Common Carrier Parcel Lockers At Transit Facilities In Portland, Oregon, Katherine Keeling, Jaclyn S. Schaefer, Miguel Figliozzi Jan 2020

Accessibility And Equity Analysis Of Common Carrier Parcel Lockers At Transit Facilities In Portland, Oregon, Katherine Keeling, Jaclyn S. Schaefer, Miguel Figliozzi

Civil and Environmental Engineering Faculty Publications and Presentations

Transit goals have typically focused on commuter trips but facilitating urban last-mile freight logistics is a potential strategy to increase transit ridership and mitigate the demands of parcel distribution on the transportation network. Presently, most parcel lockers operate out of private businesses, but consumer surveys have found that transit users may be interested in locker facilities at transit connections. The implementation of an unmanned, secure, common carrier parcel locker system could have benefits for non-transit users as well. Consolidation of deliveries is expected to benefit courier companies by allowing operations at increasingly competitive rates, and retailers and consumers benefit from …

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An Empirical Study Of The Impacts Of Bicycles On Passenger Car Speeds On Urban Roads Without Bicycle Lanes, Jaclyn S. Schaefer, Miguel Figliozzi, Avinash Unnikrishnan Jan 2020

An Empirical Study Of The Impacts Of Bicycles On Passenger Car Speeds On Urban Roads Without Bicycle Lanes, Jaclyn S. Schaefer, Miguel Figliozzi, Avinash Unnikrishnan

Civil and Environmental Engineering Faculty Publications and Presentations

Higher bicycle mode share has been suggested as part of a solution to reduce the burden of congestion in urban areas. As strategies to promote bicycling are implemented, concerns have been raised by some road users and stakeholders citing simulation based traffic studies that indicate that an increase in the bicycle mode share generates major travel time delays via reduced vehicle speeds unless bicycle lanes are provided. The current research investigates the effects bicycles may have on motorized vehicle speeds on a variety of lower speed and volume urban roads without bicycle lanes. A detailed comparative analysis of passenger car …

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Effects Of Cellulose Nano-Fiber As An Additive On Performance Of Asphalt Binders And Mixes, Marco Paulo Pereira Castro Jan 2020

Effects Of Cellulose Nano-Fiber As An Additive On Performance Of Asphalt Binders And Mixes, Marco Paulo Pereira Castro

Electronic Theses and Dissertations

Findings of a study conducted on asphalt binders and mixes modified by addition of cellulose nanofiber (CNF) to evaluate the feasibility of them as an additive is presented in the current thesis. Cellulose Acetate (CA) is an ester of cellulose and is obtained by the reaction of cellulose with acetic anhydride and acetic acid in the presence of sulfuric acid. Due to its high temperature sensitivity, high ductility, large surface area, high strain resistance, and low electrical resistivity, cellulose acetate can be used for several application. The question is if CNF can be used as an additive in the asphalt, …

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Effect Of Subsurface Microseismicity On The Motion Of Surrounding Dispersed Droplets: Supporting Information, Chao Zeng, Wen Deng Jan 2020

Effect Of Subsurface Microseismicity On The Motion Of Surrounding Dispersed Droplets: Supporting Information, Chao Zeng, Wen Deng

Research Data

The human-induced seismicity has called substantial attention in recent years. The effect of seismicity on the subsurface structure has been extensively studied. However, the effect of seismicity, especially those microseismicity, on surrounding immiscible fluids is rarely investigated. In porous media with two or more immiscible fluids, different amplitudes of vibration induced by seismicity have distinct effects on the dynamic behavior of fluids. Three types of pore-scale models are prevalent in the analysis of the motion of immiscible droplets. The underlying assumptions and accuracy of these models are compared in this study in both frequency domain and time domain. The frequency …

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Monitoring Methods And Performance Assessment For Implementation Of Low Impact Development Practices In South Dakota, Farhana Akhter Jan 2020

Monitoring Methods And Performance Assessment For Implementation Of Low Impact Development Practices In South Dakota, Farhana Akhter

Electronic Theses and Dissertations

Urbanization increases impervious surface area, which changes the hydrology of a watershed. Impervious surfaces prevent the infiltration of stormwater water into the ground surface which results in a higher volume of stormwater runoff and higher peak flow. Low Impact Development (LID) practices help to restore pre-development hydrology by increasing infiltration, evaporation, and transpiration. While the hydrologic performance of LID practices has been studied extensively and continues to be an area of active research, there has been very limited monitoring or demonstration of LID practices in South Dakota. In addition, municipalities in South Dakota and elsewhere that implement new LID practices …

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Influence Of Pumping Pressure On The Viscosity Curve And Rheological Stability Of Mortar Incorporating Polycarboxylate, Jae Hong Kim, Seong Ho Han, Byoung Il Choi Jan 2020

Influence Of Pumping Pressure On The Viscosity Curve And Rheological Stability Of Mortar Incorporating Polycarboxylate, Jae Hong Kim, Seong Ho Han, Byoung Il Choi

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

Concrete pumping has been successfully adopted in modern construction. Various concrete including high-strength concrete and self-consolidating concrete can be pumped, but we still have a lack of understanding of the rheological behavior and its change during the pumping process. This study evaluates the effect of pumping pressure on the viscosity curves of cement-based materials incorporating a specific polycarboxylate. The viscosity of mortar samples increases with the pumping pressure. The viscosity increase depends on the rate of shear strain and the polymer structure of the polycarboxylate. The effect of pumping pressure is then generalized with a Sisko model. A mechanistic model …

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Covid-19 And Public Transportation: Current Assessment, Prospects, And Research Needs, Alejandro Tirachini, Oded Cats Jan 2020

Covid-19 And Public Transportation: Current Assessment, Prospects, And Research Needs, Alejandro Tirachini, Oded Cats

Journal of Public Transportation

The COVID-19 pandemic poses a great challenge for contemporary public transportation worldwide, resulting from an unprecedented decline in demand and revenue. In this paper, we synthesize the state-of-the-art, up to early June 2020, on key developments regarding public transportation and the COVID-19 pandemic, including the different responses adopted by governments and public transportation agencies around the world, and the research needs pertaining to critical issues that minimize contagion risk in public transportation in the so-called post-lockdown phase. While attempts at adherence to physical distancing (which challenges the very concept of mass public transportation) are looming in several countries, the latest …

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Extracting Bus Transit Boarding And Alighting Information Using Smart Card Transaction Data, Zhen Chen, Wei Fan Jan 2020

Extracting Bus Transit Boarding And Alighting Information Using Smart Card Transaction Data, Zhen Chen, Wei Fan

Journal of Public Transportation

The smart card–based automated fare collection (AFC) technologies provide new opportunities for transportation data collection since smart card data (SCD) contain a significant amount of archived information that can be gathered and leveraged to help estimate public transit origin-destination (OD) matrices. Both boarding and alighting location detection are important particularly when there is no automatic vehicle location (AVL) system or other information in the database. With the analysis of raw data using limited information in this paper, an algorithm for boarding stop identification is presented after the trip direction and boarding cluster identification. Alighting stops are then identified based on …

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Mobility-As-A-Service: Assessing Performance And Sustainability Effects Of An Integrated Multi-Modal Simulated Transportation Network, Mohamed El-Agroudy Jan 2020

Mobility-As-A-Service: Assessing Performance And Sustainability Effects Of An Integrated Multi-Modal Simulated Transportation Network, Mohamed El-Agroudy

Electronic Theses and Dissertations, 2020-2023

Advances in information technology services have seen profound impacts on the state of transport services in the urban traffic environment. Mobility-as-a-Service (MaaS) represents the digital consolidation of users, operators, and public-private managing entities to provide totally comprehensive, integrated trip-making services. Users now enjoy extra flexibility for trip-making with new modal alternatives such as micro-mobility (e.g Lime Bikes, Spin Scooters) and rideshare (e.g. Lyft, Uber). However, current knowledge on the performance and interactive effects of these newer alternative modes is vague if not inconsistent. As such, these effects were studied through micro-simulation analysis of a multi-modal urban corridor in Orlando, Florida. …

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Evaluation Of Safety And Mobility Benefits Of Connected And Automated Vehicles By Considering V2x Technologies, Md Hasibur Rahman Jan 2020

Evaluation Of Safety And Mobility Benefits Of Connected And Automated Vehicles By Considering V2x Technologies, Md Hasibur Rahman

Electronic Theses and Dissertations, 2020-2023

The recent development in communication technologies facilitates the deployment of connected and automated vehicles (CAV) which are expected to change the future transportation system. CAV technologies enable vehicles to communicate with other vehicles through vehicle-to-vehicle (V2V) communications and the infrastructure through Vehicle-to-infrastructure (V2I) communications. Since the real-world CAV data is not currently available as of today, simulation is the most commonly used platform to evaluate the future V2X system. Although several studies evaluated the effectiveness of CAVs in a small roadway network, there is a lack of studies analyzing the impact of CAVs at the network level by considering both …

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A Deep Learning Approach For Real-Time Crash Risk Prediction At Urban Arterials, Pei Li Jan 2020

A Deep Learning Approach For Real-Time Crash Risk Prediction At Urban Arterials, Pei Li

Electronic Theses and Dissertations, 2020-2023

Real-time crash risk prediction aims to predict the crash probabilities within a short time period, it is expected to play a crucial role in the advanced traffic management system. However, most of the existing studies only focused on freeways rather than urban arterials because of the complicated traffic environment of the arterials. This thesis proposes a long short-term memory convolutional neural network (LSTM-CNN) to predict the real-time crash risk at arterials. The advantage of this model is it can benefit from both LSTM and CNN. Specifically, LSTM captures the long-term dependency of the data while CNN extracts the time-invariant features. …

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A Comparison Of Zinc Levels In Runoff From Rubberized Hot Mix Asphalt And Conventional Pavement, Peter A. Duin Jan 2020

A Comparison Of Zinc Levels In Runoff From Rubberized Hot Mix Asphalt And Conventional Pavement, Peter A. Duin

Cal Poly Humboldt theses and projects

High levels of dissolved zinc in water bodies can be toxic to aquatic organisms. There are currently over 40 waterways in California that have on occasion been in exceedance of Clean Water Act minimum toxicity threshold standards for zinc. Recycled tires that contain 1-2% zinc by mass are commonly used in California paving formulations known as Rubberized Hot Mix Asphalt (RHMA). The addition of tires to RHMA increases the zinc content of the pavement in comparison to conventional HMA. This research assesses the zinc content and leaching rate of RHMA in field and laboratory settings to estimate its contribution of …

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Cationic Surfactant Analysis With Good Laboratory Practice, Lawrence K. Wang, Mu-Hao Sung Wang, Nazih K. Shammas, Valerie Renak, Yung-Tse Hung Jan 2020

Cationic Surfactant Analysis With Good Laboratory Practice, Lawrence K. Wang, Mu-Hao Sung Wang, Nazih K. Shammas, Valerie Renak, Yung-Tse Hung

Civil and Environmental Engineering Faculty Publications

The objectives of this research are to: (a) demonstrate how to select an organic solvent (such as 1,1,1-trichloroethane) for spectrophotometric determination of cationic surfactant in water and wastewater, (b) investigate and recommend possible better organic solvents for surfactant analysis; and (c) introduce good laboratory practice for personal protection, laboratory protection and hazardous waste management. Specifically this research involves selection of alternate less toxic and greener organic solvent for use in a methyl orange method for colorimetric determination of cationic surfactants in the 0.2 to 2.0 mg/L range. The principles, steps and management of the methyl orange method include: (a) complexation …

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Evaluation Of The Specific Attenuation Method For Radar-Based Quantitative Precipitation Estimation: Improvements And Practical Challenges, Bong Chul Seo, Witold F. Krajewski, Alexander Ryzhkov Jan 2020

Evaluation Of The Specific Attenuation Method For Radar-Based Quantitative Precipitation Estimation: Improvements And Practical Challenges, Bong Chul Seo, Witold F. Krajewski, Alexander Ryzhkov

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

This study demonstrates an implementation of the prototype quantitative precipitation R estimation algorithm using specific attenuation A for S-band polarimetric radar. The performance of R(A) algorithm is assessed, compared to the conventional algorithm using radar reflectivity Z, at multiple temporal scales. Because the factor a, defined as the net ratio of A to specific differential phase, is a key parameter of the algorithm characterized by drop size distributions (e.g., differential reflectivity Zdr dependence on Z), the estimation equations of a and a proper number of Zdr–Z samples required for a reliable a estimation are examined. Based on the dynamic estimation …

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Impact Of Ambient Stable Stratification On Gravity Currents Propagating Over A Submerged Canopy, Jian Zhou, Subhas K. Venayagamoorthy Jan 2020

Impact Of Ambient Stable Stratification On Gravity Currents Propagating Over A Submerged Canopy, Jian Zhou, Subhas K. Venayagamoorthy

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

The structure and propagation of lock-release bottom gravity currents in a linearly stratified ambient with the presence of a submerged canopy are investigated for the first time using large-eddy simulations. The canopy density (i.e. The solid volume fraction), the strength of ambient stratification and the canopy height are varied to study their respective effects on the gravity current. Both denser canopies and stronger ambient stratification tend to switch the horizontal boundary along which the current propagates from the channel bed towards the canopy top (i.e. The through-To-over flow transition). It is found that the dilution of the current density is …

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Structural Performance Evaluation Of Dynamic Message Signs With Adhesive And Welded Joints, Ibin Amatya Jan 2020

Structural Performance Evaluation Of Dynamic Message Signs With Adhesive And Welded Joints, Ibin Amatya

Electronic Theses and Dissertations

The ultimate objective of this study was to determine the structural performance of the Dynamic Message Sign (DMS) bonded with chemical adhesive in terms of ultimate strength and fatigue strength. To achieve this objective, this study first investigated the effects of various parameters, including humidity and temperature on tensile, shear, peel, and cleavage strength through small-scale tests of adhesive specimens with variation in specimen width. The tensile, shear, peel, and cleavage specimens were conditioned in a temperature-humidity controlled chamber prior to its testing. The tensile, shear, peel, and cleavage specimens with different widths were tested according to American Society for …

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A Case Study Of Drone Delivery Reliability For Time-Sensitive Medical Supplies With Stochastic Demand And Meteorological Conditions, Travis B. Glick, Miguel Figliozzi, Avinash Unnikrishnan Jan 2020

A Case Study Of Drone Delivery Reliability For Time-Sensitive Medical Supplies With Stochastic Demand And Meteorological Conditions, Travis B. Glick, Miguel Figliozzi, Avinash Unnikrishnan

Civil and Environmental Engineering Faculty Publications and Presentations

Drones are increasingly being utilized to deliver medical supplies, and the COVID-19 pandemic has accelerated this trend. Drones arrive quickly by taking more direct paths and avoiding ground-based obstructions. However, drones are not completely reliable and may also experience failures and delays. For consumer products, delivery delays are an inconvenience, but for some medical supplies, delays may be fatal. This research focuses on the drone reliability of one particular type of supply and event: automatic defibrillators for out-of-hospital cardiac arrests (OHCA). A modeling framework is developed to analyze drone delivery reliability with stochastic demands and meteorological conditions. Using probability distributions …

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Tide-Storm Surge Interactions In Highly Altered Estuaries: How Channel Deepening Increases Surge Vulnerability, Ramin Familkhalili, Stefan A. Talke, David A. Jay Jan 2020

Tide-Storm Surge Interactions In Highly Altered Estuaries: How Channel Deepening Increases Surge Vulnerability, Ramin Familkhalili, Stefan A. Talke, David A. Jay

Civil and Environmental Engineering Faculty Publications and Presentations

We develop idealized analytical and numerical models to study how storm surge amplitudes vary within frictional, weakly convergent, nonreflective estuaries. Friction is treated using Chebyshev polynomials. Storm surge is represented as the sum of two sinusoidal components, and a third constituent represents the semidiurnal tide (D2). An empirical fit of storm surge shows that two sinusoidal components adequately represent storm surge above a baseline value (R2 = 0.97). We find that the spatial transformation of surge amplitudes depends on the depth of the estuary, and characteristics of the surge wave including time scale, amplitude, asymmetry, and surge‐tide relative phase. Analytical …

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Data Driven Synthetic Load Modeling For Smart City Energy Management Studies, Fernando Bereta Dos Reis Jan 2020

Data Driven Synthetic Load Modeling For Smart City Energy Management Studies, Fernando Bereta Dos Reis

Electronic Theses and Dissertations

The primary aim of this dissertation is to provide synthetic residential load models with granular level information on the customers having information about the appliances that constitute each individual residential customer through time. The synthetic load model is capable of being widely utilized by the power system research community since only publicly available data is utilized for its generation. This gives researcher’s access to how the synthetic load was made and also how accurate the model is in representing real power system regions. As the title of the dissertation suggests, the synthetic residential load models are intended for smart city …

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A Review Of The Second Level Construction Studies Syllabus In Ireland: In Response To A Changing Technological Environment Promoting Digital Construction, Bim Tudublin, Nigel Wearen Jan 2020

A Review Of The Second Level Construction Studies Syllabus In Ireland: In Response To A Changing Technological Environment Promoting Digital Construction, Bim Tudublin, Nigel Wearen

Capstone Reports

The zeitgeist of Construction Studies ought to adopt digital construction and work practises. However, legacy is slow to change/adapt, and a lack of awareness persists. From the perspective of the continuing legacy (vocational training) of Construction Studies being linked with industry, this research explores how the subject could evolve to deliver new digital skill sets and to meet the demands of the Architecture, Engineering, and Construction (AEC) sector.A pilot study was undertaken with 24 Transition Year students. The method and content of the study was based on an existing model from the Design Engineering Construction in the UK and was …

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Understandings Of "Global Responsibility’ Expressed By Civil Engineers Working In London, Shannon Chance, Inez Direito, J. Mitchell Jan 2020

Understandings Of "Global Responsibility’ Expressed By Civil Engineers Working In London, Shannon Chance, Inez Direito, J. Mitchell

Conference papers

This paper discusses the term ‘global responsibility’, how it emerged and why, and analysis of interview data collected from nine civil engineers working in London regarding their understandings of the term. Professional Bodies often take the lead in envisioning change, by identifying the direction their professionals should take to help address society’s evolving needs and aspirations. Often, such Bodies charge academia with addressing society’s evolving needs through research, outreach, and preparing the next generation of professionals. In the UK, leaders in civil engineering have pressed for individual and collective action to facilitate sustainable development and decrease occurrence of corruption. Nevertheless, …

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Sustainable And Resilient Construction: Current Status And Future Challenges, Niamh Murtagh, Lloyd Scott, Jingli Fan Jan 2020

Sustainable And Resilient Construction: Current Status And Future Challenges, Niamh Murtagh, Lloyd Scott, Jingli Fan

Articles

The construction industry globally is one of the most environmentally damaging of sectors. Additionally, the resources consumed and the operational energy requirements of buildings are ‘locked-in’, potentially for decades. The Intergovernmental Panel on Climate Change has recognised construction as a sector in which significant improvements can, and indeed must, be made. But the industry is often argued to be unique, in its multiplicity of stakeholders, transient organisational structures, avoidance of risk and impact on society. The current Virtual Special Issue (VSI) sought to bring together a collection of papers on progress and potential for improvement in the construction sector, in …

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Thermal Analysis And Post Construction Verification, Cormac Flood, Lloyd Scott Jan 2020

Thermal Analysis And Post Construction Verification, Cormac Flood, Lloyd Scott

Articles

Purpose – The residential sector in Ireland accounted for 25 per cent of energy related CO2 emissions in 2016 through burning fossil fuels, a major contributor to climate change. In support of Ireland’s CO2 reduction targets, the existing housing stock could contribute greatly to the reduction of space-heating energy demand through retrofit. Approximately 50 per cent of Ireland’s 2m dwellings pre-date building regulations and are predominantly of cavity and solid wall construction, the performance of which has not been extensively investigated at present. Although commitment to thermal upgrade/retrofit of existing buildings may increase under future government policies, the poor characterisation …

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Initial Transformation Of Photo-Viable Free Amino Acids In The Presence Of Surrogate And Standard Dissolved Organic Matter Under Sunlit Irradiation, Ryan J. Kibler Jan 2020

Initial Transformation Of Photo-Viable Free Amino Acids In The Presence Of Surrogate And Standard Dissolved Organic Matter Under Sunlit Irradiation, Ryan J. Kibler

Dissertations, Master's Theses and Master's Reports

With more than half of the nation’s drinking water affected by wastewater discharge from upstream and more indirect and direct reuse of treated wastewater, human health and ecotoxicological impacts resulting from effluent organic material (EfOM) will increase. Dissolved free amino acids (DFAAs), nitrogen components of EfOM, are essential nitrogen sources for microorganisms and play important roles in global N-cycling in natural aquatic environments. Several DFAAs including histidine, methionine, and tyrosine in sunlit surface waters are susceptible to direct and indirect photochemical transformation with reactive oxygen species. In this study, we investigated the reaction kinetics and initial reaction mechanisms involved in …

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Corrigendum To “Heavy Metal Ion Detection On A Microspot Electrode Using An Optical Electrochemical Probe” [Electrochem. Commun. 86 (2018) 94–98], Santanu Roy, Abhijeet Prasad, Rahul Tevatia, Ravi Saraf Jan 2020

Corrigendum To “Heavy Metal Ion Detection On A Microspot Electrode Using An Optical Electrochemical Probe” [Electrochem. Commun. 86 (2018) 94–98], Santanu Roy, Abhijeet Prasad, Rahul Tevatia, Ravi Saraf

Mid-America Transportation Center: Final Reports and Technical Briefs

The authors regret to inform an error. Ravi F. Saraf of this pub- lication discloses financial interest in Vajra Instrument as its founder and President. In accordance with its Conflict of Interest policy, the University of Nebraska-Lincoln’s Conflict of Interest in Research Committee has determined that this must be disclosed. The authors would like to apologise for any inconvenience caused.

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Applied Injected Air Into Subsurface Drip Irrigation: Plant Uptake Of Pharmaceuticals And Soil Microbial Communities, Matteo D'Alessio, Lisa M. Durso, Clinton Williams, Christopher A. Olson, Chittaranjan Ray, Ellen Paparozzi Jan 2020

Applied Injected Air Into Subsurface Drip Irrigation: Plant Uptake Of Pharmaceuticals And Soil Microbial Communities, Matteo D'Alessio, Lisa M. Durso, Clinton Williams, Christopher A. Olson, Chittaranjan Ray, Ellen Paparozzi

Nebraska Water Center: Faculty Publications

The growing global food security crisis is complicated by the need for increased crop production with less arable land and limited water resources. Reuse of treated wastewater for agricultural irrigation is becoming more common, often paired with other conservation measures such as subsurface drip irrigation (SDI). Passively injecting air into SDI systems increases crop yields and overcomes root zone wetting issues. However, when used with treated irrigation water, contaminants in the water might be taken up by the crops. This paper investigates the impact of air-injected water containing caffeine, carbamazepine, and gemfibrozil on plant uptake and soil microbial communities in …

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Safety Design Management Processes To Mitigate Design Errors, Hernan Guadalupe Jan 2020

Safety Design Management Processes To Mitigate Design Errors, Hernan Guadalupe

Walden Dissertations and Doctoral Studies

Some organizations lack processes to mitigate design errors that may result in potential accidents or loss of life during building construction. Managers are concerned about preventing injuries and accidents, which may promote safer working conditions during construction. Grounded in the transformation-flow-value theory of production, the purpose of this qualitative single case study was to explore safety design management processes that managers use to mitigate errors. The participants included 7 members from 1 design firm with business operations in the United States northeastern region. Data were collected from semistructured interviews and company document reviews. Data were analyzed using Yin's 5-phase, where …

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The Combined Toxic Effect Of Nanoparticles And Lead In The Presence Of Algae (Raphidocelis), Xuesong Liu Jan 2020

The Combined Toxic Effect Of Nanoparticles And Lead In The Presence Of Algae (Raphidocelis), Xuesong Liu

Doctoral Dissertations

"The elevated toxicity of toxic metals in the presence of nanoparticles (NPs) has raised significant concerns on the NP environmental safety. This research focuses on the impact of environmental conditions, specifically algae, on this type of toxicity. An indicator aquatic organism, Ceriodaphnia dubia (C. dubia), was used to examine the combined toxicity and toxicity mitigation from algae by monitoring its 24-h mortality. Four papers are included in this research, which focus on four aspects of the combined toxicity and the corresponding algae (Raphidocelis) impact. The first paper examines the algae impact on the combined toxicity of …

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Bond Behavior Of Advanced Fiber Reinforced Composite-Concrete Joints, Xingxing Zou Jan 2020

Bond Behavior Of Advanced Fiber Reinforced Composite-Concrete Joints, Xingxing Zou

Doctoral Dissertations

“Externally bonding advanced composite materials to concrete structures is an effective way to improve their strength, ductility, and durability. The interfacial bond behavior is fundamental to understand the overall structural performance of concrete structures strengthened with advanced composite materials. This study includes a comprehensive investigation of the bond behavior of composite-concrete joints with different fiber reinforced composite types. First, a direct approach to determine the bond-slip relationship for fiber reinforced cementitious matrix (FRCM)-concrete joints based on fiber strain measurements was proposed. Then, an analytical solution to predict the full-range response of FRCM-concrete joints was derived by assuming a trilinear bond-slip …

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