Civil and Environmental Engineering Commons^™

Hydrothermal Processing Of Biomass For Biofuels, Sandeep Kumar

Civil & Environmental Engineering Faculty Publications

[First paragraph] In recent years, significant research interests have been placed on the conversion of non-food biomass resources such as lignocellulosic biomass (terrestrial) and algae (aquatic) to biofuels. Among all the alternative or renewable energy options, biomass is the only resource which is carbon neutral and can potentially replace part of fossil fuels use as liquid transportation fuels as well as contribute to electricity generation. Therefore, it can play a significant role in partially replacing oil, natural gas, and coal utilization for heat and energy generation. However, high moisture content of fresh biomass or algae is one of the major …

Quantifying Risks Of Climate Change And Sea Level Rise To Naval Station Norfolk (Serdp Rc-1701), Kelly Burks-Copes

October 2, 2013: Quantifying Risks and Moving Forward

No abstract provided.

Denitrification And Biological Phosphorus Removal Using Focused, Pulse-Treated, Thickened Waste Activated Sludge As An Internal Carbon Source, Holly Anne Hillard

Civil & Environmental Engineering Theses & Dissertations

Recent research shows that an internal carbon source, derived from the treatment of waste activated sludge (WAS), could be used as an alternative to external carbon sources for denitrification in biological wastewater treatment processes. In this study, a thickened waste activated sludge (TWAS) treatment technology, developed by the company OpenCEL, was used to treat TWAS with pulsed electric fields (PEF) to transform it into an organic substrate for heterotrophic denitrification in a biological nutrient removal (BNR) system. If effective, this technique could significantly reduce the external carbon source demand.

To determine the utility of OpenCEL-treated TWAS as an internal carbon …

Operation And Modification Of A B-Stage For Efficient Nitrogen Removal In An A/B Process Pilot Study, Ryder Bunce

Civil & Environmental Engineering Theses & Dissertations

Hampton Roads Sanitation District's Chesapeake-Elizabeth Wastewater Treatment Plant is a High-Rate Activated Sludge (HRAS) plant with no primary clarifiers. The plant operates at an SRT of 1.5 - 2 days and does not perform biological nitrogen removal (BNR). By 2021 HRSD anticipates the plant will be included in a bubble permit, resulting in a total nitrogen (TN) effluent target of approximately 5-8 mg/L. Converting the plant to a conventional BNR process would require a significant increase in reactor volume. Capital costs for the upgrade are estimated at 125 -150 million dollars, with a dramatic increase in operating costs as well. …

Dimensionless Criteria For Selecting Tidally-Influenced Advective-Dispersive Desalination Brine Mixing Plume Characterization Models, Alireza Shahvari

Civil & Environmental Engineering Theses & Dissertations

The very nature of requirements for implementing a desalination process is highly spatial due to the need to secure both a source for the operation and sink for brine dilution. Thus, the applicable coastal location is bound to natural tidal mixing characteristics and subjected to a near- or a far-field availability for source and sink. Mixing characteristics of coastal waters are very different from one point to another due to the spatiotemporal tidal characteristic in loco in a manner that it can vary from being highly advective to completely dispersive dominant. Once a location is identified, estimation of corresponding water …

Optimization Of Demon® Sidestream Treatment And Potential For Anammox Mainstream Bioaugmentation, Andrea Lauren Nifong

Civil & Environmental Engineering Theses & Dissertations

Anaerobically digested sludge dewatering liquors (e.g. centrate) can represent 15-25% of the total kjeldahl nitrogen (TKN) load on a typical municipal waste water treatment plant (WWTP). Sidestream nitrogen removal has been demonstrated to be an effective tool for improving nitrogen removal performance and reliability with a savings in aeration energy, chemicals (supplemental alkalinity and carbon), and sludge production.

Deammonification, partial nitritation by ammonia oxidizing bacteria (AOB) combined with anaerobic ammonium oxidation (AMX or anammox), provides near complete nitrogen removal with a 65% reduction in energy and 100% reduction in supplemental carbon and alkalinity requirements as compared to traditional nitrification-denitrification. The …

Parallel Implementations Of The Frank-Wolfe Algorithms For The Traffic Assignment Problem, Shawn Eugene Allen

Computational Modeling & Simulation Engineering Theses & Dissertations

Transportation planners seek to understand how to best invest limited resources for future transportation network development. The traffic assignment problem is one algorithm of great importance to planners because it provides insight into how traffic will flow within the network. The Frank-Wolfe algorithm is a traditional solution method for this optimization problem, but it has been characterized by its slow rate of convergence and poor computational performance. This thesis examines and implements several modern advancements in this algorithm which are designed to improve the rate of convergence.

In addition to algorithm changes, another method to improve the performance of an …

Linear Programming Algorithm With Mixed Real-Integer Variables In Matlab Environments, Gelareh Bakhtyar

Civil & Environmental Engineering Theses & Dissertations

Efficient numerical procedures for solving general Linear Programming (LP) problems with mixed real-integer variables are developed in this work. The proposed algorithms employ the revised dual simplex with Branch and Bound (B&B) algorithms, with special procedures for limited search of subsequent branches. Computational time can be significantly reduced by incorporating the updated inverse formulas into the developed procedures. Both generic LP problems and deterministic pavement maintenance and rehabilitation (M&R) problems are used in this study to vaiidate the developed procedures. Medium to large-scale examples ( 11 pavement M&R) presented in this work have demonstrated that the developed numerical procedures consistently …

The Role Of Proximity In Reducing Auto Travel: Using Vmt To Identify Key Locations For Development, From Downtown To The Exurbs, Robert B. Case

Civil & Environmental Engineering Theses & Dissertations

The purpose of this dissertation is to discover the VMT impact of each level of proximity in order to help government identify key locations for housing development, and thereby lower VMT and reduce dependence on foreign oil. By discovering the VMT impact of each level of proximity, this dissertation provides a) the first known means of calculating the proximity-based VMT benefit of subject locations by individual proximity level, and b) the new finding that it is likely that high VMT benefit can be achieved at moderate proximity levels acceptable to many households, enabling representative governments to be politically successful while …

Evaluating Alternatives For Augmented Water Quality Improvement Utilizing Oyster Restoration As Best Management Practice (Bmp), Stephanie Roberts Long

Civil & Environmental Engineering Theses & Dissertations

Due to several anthropogenic influences, the Chesapeake Bay has experienced a marked decrease in water quality since the colonists arrived at the Jamestown settlement in Virginia during the 1600s. Higher concentrations of nitrogen and phosphorus have enriched the estuaries and coastal waters via point sources (sewage treatment plants and industrial wastes), nonpoint sources (agricultural run-off and septic tank discharges) and the atmosphere (Newell et al., 2005). Restoring oyster beds is considered a Best Management Practice (BMP) to improve water quality as well as provide physical habitat for aquatic species and a healthier estuarine system (USACE Native Oyster Restoration Master …

An Investigation Of Pavement Distress Variables On Crash Outcomes Using Hierarchical Generalized Linear Regression Modeling, Robert Alan Morgan

Civil & Environmental Engineering Theses & Dissertations

Previous macro-level studies show that the condition of the pavement is associated with roadway safety. However, this premise has not been examined on a micro-level using detailed pavement distress variables (PDVs). The main focus of this research will be to expand the use of the PDV data to further understand the safety risks associated with the type of pavement and each individual PDV by analyzing the likelihood of having a rear-end and/or injurious crash, given that a crash occurs.

Sample crash data and PDV data from the Commonwealth of Virginia for the years 2007 and 2008 were used to produce …

Large-Scale Incidents Modeling And Network Simulation, Yichi Zhang

Civil & Environmental Engineering Theses & Dissertations

Traffic incidents on urban freeways are a major source of congestion and travel time uncertainty. In particular, large-scale incidents have longer durations and need more incident response resources. As such, large-scale incidents deserve more attention by practitioners and researchers. The objective of this study is to analyze large-scale incidents and explore their correlates and implications for traffic operations. An innovative analysis method, based on a 2008 incident data set from the Hampton Roads Traffic Operation Center (HRTOC) in Hampton Roads, Virginia was developed (N=59176). This study defined large-scale incidents as having a two hour minimum duration, based on guidance from …

Recurrent Coastal Flooding: How Should Virginia Respond?, Molly Mitchell Rogerro

March 13, 2013: Regional Sea Level Rise Assessment, Adaptation and Flood Mitigation Projects

No abstract provided.

City Of Norfolk Coastal Flood Mitigation Program, Brian Joyner

March 13, 2013: Regional Sea Level Rise Assessment, Adaptation and Flood Mitigation Projects

No abstract provided.

Fema Region Iii Coastal Storm Surge Study, Mike Forte, Jeff Hanson, Michelle Hamor

March 13, 2013: Regional Sea Level Rise Assessment, Adaptation and Flood Mitigation Projects

No abstract provided.

Asbpa Sea Level Rise Findings, Maura Boswell

March 13, 2013: Regional Sea Level Rise Assessment, Adaptation and Flood Mitigation Projects

No abstract provided.

Willoughby Spit Shoreline Improvement Project Of Ocean View Beach, Maura Boswell

March 13, 2013: Regional Sea Level Rise Assessment, Adaptation and Flood Mitigation Projects

No abstract provided.

Usace Flood Risk Management Partners In Shared Responsibility, Michelle Hamor

March 13, 2013: Regional Sea Level Rise Assessment, Adaptation and Flood Mitigation Projects

No abstract provided.

Resilience Quantification And Its Application To A Residential Building Subject To Hurricane Winds, Berna E. Tokgoz, Adrian V. Gheorghe

Engineering Management & Systems Engineering Faculty Publications

In order to overcome negative consequences of a disaster, buildings and infrastructures need to be resilient. After a disaster occurs, they must get back to their normal operations as quickly as possible. Buildings and infrastructures should incorporate both pre-event (preparedness and mitigation) and post-event (response and recovery) resilience activities to minimize negative effects of a disaster. Quantitative approaches for measuring resilience for buildings and infrastructures need to be developed. A proposed methodology for quantification of resilience of a given building type based on different hurricane categories is presented. The formulation for the resilience quantification is based on a model embedding …

Simulation Modeling And Analysis Of Complex Port Operations With Multimodal Transportation, Mariam Kotachi, Ghaith Rabadi, Mohammad F. Obeid

Engineering Management & Systems Engineering Faculty Publications

World trade has been increasing dramatically in the past two decades, and as a result containers exchange has grown significantly. Accordingly, container terminals are expanding to meet this increase and new container ports have opened. Ports with one or more container terminals are considered complex systems in which many resources, entities and transporters interact to achieve the objective of safely moving containers delivered by ships inland as well as loading containers delivered by trucks and rail onto ships. Ports with multimodal transportation systems are in particular complex as they typically operate with ships arriving to one or more terminals, multiple …

Exploring Travel And Activity Behavior In Transit-Oriented Developments: Insights Into Transportation Benefits And Travel Demand Modelling, Sanghoon Son

Civil & Environmental Engineering Theses & Dissertations

As a sustainable urban development and transportation planning strategy, researchers and planners are increasingly interested in transit-oriented development (TOD). By integrating transit system and neighborhood design, TOD aims to provide a livable environment that is alternative mode friendly, higher density, and mixed-use to residents and workers in the vicinity of transit stations. Despite the recent growing interest in TOE), however, transportation benefits of TOD are not well quantified and characteristics of TOD are not adequately reflected in travel demand models.

This dissertation contributes to understanding of the travel and activity behavior by comprehensively exploring them in the context of TOD. …

Thermo-Elasto-Plastic Behavior Of Biaxially Loaded Steel Beam-Columns Inducing Those From World Trade Center Towers, Yanhong Zhao

Civil & Environmental Engineering Theses & Dissertations

An experimental and theoretical investigation into the behavior of biaxially loaded steel beam-columns is conducted including the effects of high temperature. Systems of materially nonlinear differential equations of beam-column equilibrium are first formulated for both ambient and high temperature conditions. An iterative finite integral procedure is formulated and programmed to solve the governing differential equations. To check the validity of the theoretically predicted behavior and strength of the beam-columns, a series of forty-two laboratory tests are conducted at both ambient and high temperature up to 950°F. Upon achieving a good agreement between the predicted beam-column behavior and that observed in …

Watershed-Scale Hybrid Stochastic-Deterministic Modeling Framework And Diffused Sources Superpositioning, Ruby Juvah Damalie

Civil & Environmental Engineering Theses & Dissertations

Predicting hydrologic system behavior is imperative to planning and management of water resources. The study developed an integrated hybrid stochastic and deterministic framework to improve prediction accuracy for overland flow and diffused sources in a watershed. The methodology includes sampling input parameters at system level and contribution of nonpoint source from hydrologically disconnected areas (heretofore referred to as system-level approach and superpositioning respectively). System-level approach includes the integration of a topography-based sampling grid generalized linear model developed by the study and Monte Carlo methods. The superpositioning method adopts in-stream water quality equation for overland flow pollution estimation.

The system-level approach …

Impact Of Data Resolution On Peak Hour Factor Estimation For Transportation Decisions, Jan-Mou Li, Lee D. Han, Chung-Hao Chen

Electrical & Computer Engineering Faculty Publications

Inductance loop detection systems serve as a primary data source to contemporary traffic information systems. Measures like 20-second or 30-second average velocity, flow, and lane occupancy can be aggregated from individual loop detector actuation sampled at 60 Hz typically. Practically, these measures would sometimes be further aggregated into a much lower, e.g. 15-minute, resolution and then the raw data were lost. Valuable traffic information like flow variation may be distorted when the lower resolution aggregation is practiced. A biased conclusion could be drawn from a data integration system consisted of this kind of distortions. Three approaches estimating a peak hour …

Path Clearance For Emergency Vehicles Through The Use Of Vehicle-To-Vehicle Communication, Craig Jordan, Mecit Cetin, R. Michael Robinson

VMASC Publications

The study described in this paper evaluated and tested a new strategy to enable emergency response vehicles (EVs) to navigate through congestion at signalized intersections more efficiently. The proposed strategy involves the use of vehicle-to-vehicle communication to send messages to alert vehicles to the approach of the EV and to provide specific instructions on maneuvering to allow the EV to proceed through congested signalized intersections as quickly as possible. This movement is achieved by creation of a split in the vehicle queue in one lane at a critical location to allow the EV to proceed at its desired speed but …

Biaxial Bending And Lateral-Torsional Instability Of Imperfect Frp I-Beams Including Effects Of Retrofitting, Jodi Marie Knorowski

Civil & Environmental Engineering Theses & Dissertations

This thesis presents the outcome of a theoretical and experimental study of the behavior of Fiber Reinforced Polymer (FRP) I-beams susceptible to lateral-torsional instability or when subjected to biaxial bending. Laboratory experiments involved application of vertical and horizontal static loads to a 4 x 4 x ¼ in. I-beam with various lengths, and the resulting displacement, twist, and strain were recorded. In the vertical direction, the beam was loaded from different reference load heights with respect to the shear center of the beam. The governing biaxial flexure and torsion differential equations were modified to account for the presence of initial …

Demand Responsive Signal Control Strategy (Drsc) Incorporating Queue Length Information In Real-Time Signal Control, Rahul Rajbhara

Civil & Environmental Engineering Theses & Dissertations

Most of the existing vehicle detection systems, namely inductive loops, video cameras etc. are incapable of measuring the queue lengths at signalized intersections. However, with the advent of modern technology, newer detection methods such as probe vehicles equipped with wireless communications (Connected Vehicles), particularly under the Vehicle Infrastructure Integration [52), and radar detection currently provide this capability [53). This thesis presents a Demand Responsive Signal Control Strategy (termed as DRSC) for an isolated signalized intersection. The control strategy incorporates real-time queue length information (obtained from probe vehicles) into the signal control logic. Demand based maximum green time for each upcoming/new …

Probabilistic Resilience Quantification And Visualization Building Performance To Hurricane Wind Speeds, Berna Eren Tokgoz

Engineering Management & Systems Engineering Theses & Dissertations

Natural and man made disasters are unpredictable and unavoidable in today's world. Their frequency of occurrence and damages keep increasing. Due to the efforts to reduce negative consequences from such disasters, the concept of resilience has gained so much popularity in disaster management area especially after disasters like the September 11 attacks and Hurricane Katrina. Complex systems of today are under operational risks because of increasing threats and their high level of vulnerability. Hence, such systems need to adapt the concept of resilience for continuous operations. Resilience is a proactive concept which should incorporate both pre-event (preparedness and mitigation) and …

Efficient Stand-Alone Generalized Inverse Algorithms And Software For Engineering/Sciences Applications: Research And Education, Subhash Chandra Bose S V Kadiam

Civil & Environmental Engineering Theses & Dissertations

Efficient numerical procedures for finding the generalized (or pseudo) inverse of a general (square/rectangle, symmetrical/unsymmetrical, non-singular/singular, real/complex numbers) matrix and solving systems of Simultaneous Linear Equations (SLE) are formulated and explained. The developed procedures and its associated computer software (under MATLAB computer environment) have been based on "special Cholesky factorization schemes" (for a singular matrix), the generalized inverse of the matrix product, and were further enhanced by the Domain Decomposition (DD) formulation.

Test matrices from different fields of applications have been chosen, tested and compared with other existing algorithms. The results of the numerical tests have indicated that the developed …

Clearing Paths For Emergency Vehicles Using Shock Wave Theory And Vehicle-To-Vehicle Communication, Craig Austin Jordan

Computational Modeling & Simulation Engineering Theses & Dissertations

A new strategy to enable an EV to navigate through congestion at signalized intersections more efficiently has been developed and is presented in this thesis. The proposed strategy involves communicating control messages to vehicles to change their driving behavior and to traffic signals to change their timing plans so that EV s can proceed through congested intersections as quickly as possible. To achieve this, specific vehicles are instructed to hold their positions to create a split in the vehicle queue at a critical location in one lane. The split allows the EV to change lanes and proceed unimpeded at its …