Engineering Commons^™

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 …

Modelling The Addition Of Limestone In Cement Using Hydcem, Niall Holmes, Denis Kelliher, Mark Tyrer

Conference papers

Hydration models can aid in the prediction, understanding and description of hydration behaviour over time as the move towards more sustainable cements continues.

HYDCEM is a new model to predict the phase assemblage, degree of hydration and heat release over time for cements undergoing hydration for any w/c ratio and curing temperatures up to 450C. HYDCEM, written in MATLAB, complements more sophisticated thermodynamic models by predicting these properties over time using user-friendly inputs within one code. A number of functions and methods based on up to date cement hydration behaviour from the literature are hard-wired into the code along with …

Hydcem: A New Cement Hydration Model, Niall Holmes, Denis Kelliher, Mark Tyrer

Conference papers

Hydration models are useful to predict, understand and describe the behaviour of different cementitious-based systems. They are indispensable for undertaking long-term performance and service life predictions for existing and new products for generating quantitative data in the move towards more sustainable cements while optimising natural resources. One such application is the development of cement-based thermoelectric applications.

HYDCEM is a new model to predict the phase assemblage, degree of hydration, heat release and changes in pore solution chemistry over time for cements undergoing hydration for any w/c ratio and curing temperatures up to 450C. HYDCEM, written in MATLAB, is aimed at …

Physical Modeling Of Flow Nets In Groundwater And Determination Of Hydraulic Conductivity, Hannah Nicholas, Moses Karakouzian

AANAPISI Poster Presentations

The goal of this study is to physically model the paths that water particles take through soil, and estimate hydraulic conductivity for several soil configurations. Water paths, or flow lines, are shown by injecting dye into sand contained in a rectangular acrylic glass tank with a vertical barrier in the center; water is poured on one side of the tank and a pump is used to maintain constant head loss. If flow lines are formed, a flow net is to be drawn using photos of the tank and hydraulic conductivity is to be calculated.

This project consists of four phases: …

High Recovery Inland Desalination: A Technical And Economic Performance Evaluation Of Zero Discharge Desalination And Other Technologies, Malynda Aragon Cappelle

Open Access Theses & Dissertations

Increasing population and diminishing freshwater resources are leading to increased competition between users of freshwater, both in terms of surface water and groundwater. Desalination can augment the water supply, but conventional approaches like reverse osmosis are usually limited to 70-80% recovery. Inland brine disposal options are often limited, presenting significant technical and economic obstacles to implementing desalination technology. In comparison to conventional desalination technologies, high recovery desalination methods such as Zero Discharge Desalination (ZDD) offer substantially higher potable water yield (i.e., 95-98%) from brackish water. ZDD is a hybrid process that combines reverse osmosis (RO) or nanofiltration (NF) with electrodialysis …

The Stability And Ecophysiological Realism Of Calibrated Parameters In A Detailed Vegetation Model (Waves), R. W. Vervoort, J. D. Henry, M. Gharun, M. A. Adams

International Congress on Environmental Modelling and Software

WAVES is a daily time-step one-dimensional vegetation, water and energy transfer model that has been used extensively across Australia (and globally) to simulate ecohydrological processes. In particular it has been used extensively for assessing future recharge under climate change. A literature review suggests parameter values from the user manual are most commonly used in research. This suggests that further investigation into the stability and equifinality of the parameters might be warranted, specifically since the model is used for scenario studies. This study made use of an extensive sapflow and soil moisture data set for 7 tree vegetation sites in the …

Ncma Groundwater Model Using Usgs Modflow-2005/Pest, Brian Matthew Wallace

Master's Theses

A numerical model for the NCMA aquifer complex is presented. The objective of the study is to develop a numerical groundwater model for the NCMA aquifer system to enhance the understanding of subsurface groundwater flow. Infiltration, streamflow, pumping, and return flows are implemented to characterize the aquifer complex over time. The numerical model is calibrated to municipal and monitoring well data, average monthly water balances, and hydraulic contours. Transient aquifer inflows and outflows are assessed in the results of the study and are compared to balance terms from previous studies. The 2007 Todd Engineers Study subsurface inflows and outflows generate …

Influence Of Water Chemistry Parameters On The Dissolution Rate Of The Lead (Ii) Carbonate Hydrocerussite, Caitlin Se Kushnir

Electronic Thesis and Dissertation Repository

This work has focused on the kinetic dissolution of the lead (II) carbonate hydrocerussite (Pb₃(CO₃)₂(OH)₂) under four pH conditions (7.5, 8, 9, 10), three dissolved inorganic concentrations (DIC; 10, 20, 50 mg C/L), and three initial hydrocerussite concentrations (10, 20, 50 mg/L) in batch experiments. Experiments were performed in at least duplicate to determine total dissolved lead dissolution curves at short time scales (hr.). All equilibrium dissolved lead concentrations were achieved in 40 minutes or less, and matched trends from previous studies; pH 7.5 and pH 10 corresponding to the highest and …

Methane Production By A Packed-Bed Anaerobic Digester Fed Dairy Barn Flush Water, Sean Richard Thomson

Master's Theses

Packed-bed digesters are an alternative to covered lagoon digesters for methane production and anaerobic treatment of dilute wastewaters such as dairy barn flush water. The physical media of packed-beds retain biofilms, often allowing increased treatment rates. Previous studies have evaluated several types of media for digestion of dilute wastewaters, but cost and media fouling have setback commercial development. A major operational cost has been effluent recirculation pumping.

In the present effort, a novel approach to anaerobic digestion of flush dairy water was developed at pilot-scale: broken walnut shells were used as a low-cost packed-bed medium and effluent recirculation was replaced …

Influence Of Fly Ash On Surface Chloride Concentration Under Shallow Immersion Condition, Jun Liu, Xiaodong Wang, Feng Xing, Ningxu Han

International Conference on Durability of Concrete Structures

In this paper, the influence of fly ash content on concrete surface chloride concentration was investigated through periodical tests of surface chloride concentration of concrete by immersing three kinds of concrete specimens in 5.0 wt.% sodium chloride solution. One kind of specimen is common concrete without fly ash, whereas the other two kinds of specimens are mixed with fly ash. The results show that the surface chloride ion concentration ranges from 0.295 to 0.777 wt.% for the immersed concrete samples in this study; in the initial stage of immersion, the concrete surface chloride ion concentration is affected by added fly …

Development Of Safety Performance Functions For Non-Motorized Traffic Safety, Hamidreza Ahady Dolatsara

Masters Theses

This study investigates the factors which affect the safety of non-motorized transportation within the influence area of intersections to enhance development of safety performance functions (SPFs). The scope of this study is limited to the four Michigan cities of Ann Arbor, East Lansing, Flint and Grand Rapids. Due to the current lack of research regarding the appropriate size of the influence area, this study investigates the distance of crashes relative to the center of 148 intersections to identify the most probable area of influence for different crash types. For motorized and non-motorized crashes, 240 ft. and 137 ft. are proposed, …

A Framework To Predict High Risk Roadways For Pedestrians In Tennessee, Zane Hunter Pannell

Masters Theses

Pedestrians and bicyclists are a class of vulnerable road users that are often over-represented in incapacitating injury or fatal crash statistics. Because non-motorized trips are vital to many urban and rural residents for utility or recreation and exercise, it is essential to identify safety deficiencies in our existing transportation infrastructure to address rising injuries and fatalities among this group of road users. As the economy continues to struggle and fuel prices remain high, many cities and rural transportation agencies are seeing large increases in bicycling, walking, and transit ridership. While passenger car fatalities have shown sharp declines in the last …

Xpswmm Analysis Of The Ornl Stormwater Collection System Up To Outfall 211, Heidi Belle Henderson

FIU Electronic Theses and Dissertations

The Oak Ridge National Laboratory, Tennessee, was the site for a number of US Government projects during the 1940s and 1950s including the development of thermonuclear weapons. Chemical processes conducted at the site as part of these projects resulted in contamination of certain building areas at the ORNL. The purpose of this study is to develop a hydraulic-hydrologic computer model via XPSWMM to determine surface water flow rates and water stages within the drainage system during rainfall events and introduce a conservative contaminant into the system to trace peak concentrations of contaminants.

The model was calibrated by simulating actual rainfall …

Evacuee Route Choice Decisions In A Dynamic Hurricane Evacuation Context, R. Michael Robinson, Asad Khattak

VMASC Publications

Very high traffic volumes may lead to extensive congestion during hurricane evacuations. Evacuation planners reduce this congestion by careful planning for multiple hurricane scenarios and assignment of evacuation routes and timing. This planning may be for naught if obstructions block key roadways. An advanced traveler information system (ATIS) may be used to guide evacuees to alternate routes, but how effective will that guidance be? Should the use of alternate routes be encouraged? How are drivers likely to respond to delays and information? Will information shorten or improve the reliability of travel times in emergency conditions? Integration of a dynamic evacuation …

High-Resolution Numerical Simulation Of Tidal Enegry Distribution Along The New Jersey Coastline And Influence Of Sea-Level Rise, Simon Kraatz

Dissertations and Theses

No abstract provided.

An Empirical Model For Build-Up Of Sodium And Calcium Ions In Small Scale Reverse Osmosis, Subriyer Nasir

Makara Journal of Technology

A simple models for predicting build-up of solute on membrane surface were formulated in this paper. The experiments were conducted with secondary effluent, groundwater and simulated feed water in small-scale of RO with capacity of 2000 L/d. Feed water used in the experiments contained varying concentrations of sodium, calcium, combined sodium and calcium. In order to study the effect of sodium and calcium ions on membrane performance, experiments with ground water and secondary effluent wastewater were also performed. Build-up of salts on the membrane surface was calculated by measuring concentrations of sodium and calcium ions in feed water permeate and …

Construction Cost Models, Barry Dikeman

Economics and Finance

The following are a series of cost estimate models similar in format to a typical engineer’s estimate that were developed in support of our financial impact assessment report for LD 1725. The models us current material costs, labor costs, and equipment costs for the region to provide a comparative cost analysis of seven culvert replacement scenarios. The models provide information about what the cost impact of LD 1725 would be for typical culvert replacements in Maine. However, due to the inherent restrictions of the cost modeling framework we were not able to include the abundance of variables that would be …

A Gasoline Demand Model For The United States Light Vehicle Fleet, Diana Rey

Electronic Theses and Dissertations

The United States is the world's largest oil consumer demanding about twenty five percent of the total world oil production. Whenever there are difficulties to supply the increasing quantities of oil demanded by the market, the price of oil escalates leading to what is known as oil price spikes or oil price shocks. The last oil price shock which was the longest sustained oil price run up in history, began its course in year 2004, and ended in 2008. This last oil price shock initiated recognizable changes in transportation dynamics: transit operators realized that commuters switched to transit as a …

Benchmark Studies For Structural Health Monitoring Using Analytical And Experimental Models, Jason Lee Burkett

Electronic Theses and Dissertations

The latest bridge inventory report for the United States indicates that 25% of the highway bridges are structurally deficient or functionally obsolete. With such a large number of bridges in this condition, safety and serviceability concerns become increasingly relevant along with the associated increase in user costs and delays. Biennial inspections have proven subjective and need to be coupled with standardized non-destructive testing methods to accurately assess a bridge's condition for decision making purposes. Structural health monitoring is typically used to track and evaluate performance, symptoms of operational incidents, anomalies due to deterioration and damage during regular operation as well …

Adapting The Modified Cam Clay Constitutive Model To The Computational Analysis Of Dense Granular Soils, Jose Arvelo

Electronic Theses and Dissertations

The computational constitutive Modified Cam Clay Model (MCCM) was developed at Cambridge to study the behavior of clays and has been proven to be effective. In this study, this model is extended to the case of dense sands to analyze the accuracy of the stress-strain behavior. This analysis is based on triaxial test data applied to remolded and compacted sand samples under drained conditions. The laboratory triaxial tests were performed by the Florida Department of Transportation to research the permeability effect in sandy soils compacted up to 95% of maximum unit weight at the optimum moisture content. Each soil sample …