Filamentous bulking is a widespread problem in activated sludge wastewater treatment plants. In North Carolina, 63% of wastewater treatment plants (WWTPs) surveyed have experienced bulking. Determining the dominant bulking-causative bacteria and their level of proliferation is a necessary step in bulking control. This study used molecular techniques, i.e. quantitative Fluorescent in situ Hybridization (FISH) and membrane hybridization to identify and quantify the specific filamentous microorganisms and their threshold values for causing bulking in both lab scale reactors and full scale treatment plants. Filament length of a specific filamentous organism, Eikelboom Type 1851, correlated strongly with the sludge volume index (SVI) and was identified to be the major bulking-causative microorganism in lab scale reactors and a full scale activated sludge plant. The full scale plant is a biological nutrient removal (BNR) plant, a common operational mode in North Carolina, suggesting that this organism may be prevalent in North Carolina WWTPs. The threshold value for Eikelboom Type 1851-caused-bulking was determined. This threshold value will allow the monitoring of incremental improvements in control methods and the delineation of the niche of Eikelboom Type 1851 in activated sludge. Furthermore, the lab scale experiments verified the kinetic selection theory and the filamentous backbone theory for Type 1851.

This research evaluates pavement marking performance characteristics of NCâs highways and proposes asset management guidelines that will enable NC to effectively implement new Federal standards. Predictive models were developed and used to forecast the performance of pavement markings retroreflectivity over time. Consideration was given to the analysis of the relationships between pavement marking retroreflectivity values and variables such as marking color, marking age, pavement surface, and lateral location. Understanding retroreflectivity performance over time facilitated the development and implementation of guidelines and tools that will be used for holistic asset management. The guidelines and tools enable pavement-marking managers to focus limited resources where they are most needed and avoid replacing materials with effective life still remaining. Additionally, this research provides a means for NCDOT to establish the condition state of pavement markings throughout the State of North Carolina, This can be used to determined if they will be in compliance with pending minimum retroreflectivity standards that the Federal Highway Administration is proposing to publish.

With the sensor technology in-place today, it is difficult to correctly predict path utilization coefficients (PUCs: the percentage of an origin-destination (OD) pairâs traffic flows traveling on a given path or route) because the problem is hugely underspecified, requiring inference to overcome the under-specificity. The shortcoming of this method, as discussed in detail, is that the inference rules applied may be wrong. In fact, little path flow research has addressed the issues of (a) reliability in the instrumentation, (b) reliability of other input data or models, (c) reliability and confidence level of the path flows solution, (d) the relationship between what is observed and what is inferred, and (e) verifying that defined path flows are those actually occurring in the network (and discerned), which are all directly relevant to the practical application of path flow estimation and to guiding instrumentation research to meet the needs of the evolving world of transportation. Therefore, this dissertation research addresses the key questions of (1) how well can path flow rates be determined from an instrumented network, and (2) how much inference is required to yield reasonable estimates of all path utilization coefficients in a network. It was discovered that observed link flow data are only slightly better than spurious input data for PUC prediction; automatic vehicle identification (AVI) or automatic vehicle location (AVL) data are required to significantly improve predictions. Therefore, significant value is added by collecting AVI and AVL data to estimate PUCs or OD flows. Moreover, if predicting link volumes is desired, then link volume observations are also necessary â AVI or AVL data are insufficient. Considering these results, all network analyses are critically dependent upon good utilization coefficient estimates to obtain reasonable flows which, in-turn, are essential for decision-makers. This is true whether you are attempting to estimate OD flows or PUCs (say as a modeler), desiring to make good capacity investment decisions, or trying to make real-time network flow management decisions. In all cases, good quality PUCs are necessary; reliance on link flow observations would require heroic inference assumptions so AVI and/or AVL data are better choices for PUC prediction. Within this dissertation are four components to support this research endeavor and the conclusions drawn. First is a discussion of the theoretical constructs involved in the path utilization rate estimation process. Second, a methodology for estimating PUCs is presented. Third, numerical tests of the methodology are conducted on several hypothetical networks. Fourth, throughout this research three data conditions were examined to test the methodology's predictions â error-free data, stochasticity in demands coverage (such as in OD flows, link volumes, a priori path utilizations, and a priori link utilizations), and stochasticity in the demand measurements.

This research is the second part of a two-part research process to develop a pile jetting model which encompasses pile insertion, debris zone modeling, and particle transport. The first part of the research was composed of development of a comprehensive laboratory experimental program which provided insight into the effects of jetting parameters (i.e. water volume flowrate and jet nozzle velocity) on maximum pile insertion depth, pile insertion rate, volume of debris transported to the ground surface, and the extent of the debris zone area (installation characteristics). This research is composed of model development and verification of the laboratory model based on twenty six full-scale pile installations at four different test sites. Various pump configurations and soil profiles are investigated. Results of the field test program show that the proposed debris zone model based on the laboratory experimental program agrees well with the measured debris zone volumes generated at the field installations. A pile insertion model is developed and validated, the laboratory debris zone model is verified, and referenced particle transport equations from literature are presented. Recommended design procedures for using the jetted pile model are discussed.

The management of large capital improvement construction programs involves the efforts of both internal staff and external service providers. An understanding of how construction programs are managed, either through internal or external staff, is essential in tracking future trends and determining improvements and best practices in the management process. To address this need a survey was developed by a focus group of industry professionals. The survey was distributed to the membership of a number of professional organizations that represented owners within the construction industry. The survey attempted to determine both the current status of managing a construction program throughout a broad range of demographic characteristics (including the definition of program management) and the hiring of an external program manager. The survey and subsequent analysis that focused on the management of a construction program examined the following key points: role of a program manager, internal capabilities, outsourcing, sourcing strategy, and management costs. The survey and subsequent analysis that focused on hiring an external program manager examined: program management fees, type of firms used in managing a construction program, factors considered when hiring a program manager, and organizational structure. The results of the survey have also been segregated by public and private organizations to denote any differences in the management of public and private construction programs. A key contribution of this research was determining the percentage of outsourcing within each phase of the construction process and the number of service providers considered in the selection process. Also, a multifaceted definition of program management was developed from the research for use in clarifying the concept of program management within construction.

The evacuation of vulnerable coastal areas in the event of an emergency such as an impending hurricane has become a significant safety issue due to the rapid growth of both permanent and tourist populations in these areas. Highway capacity has often not been upgraded in line with this demand growth. In the case of Hurricane Floyd in 1999, evacuations of areas of North and South Carolina resulted in several highly congested primary highways and, as a result, several states created Lane Reversal Plans for interstates and/or divided highways along evacuation routes. However, these plans were created with little data to rely on as to their efficiency. A major research study was funded by the North Carolina Department of Transportation (NCDOT) to use simulation modeling to investigate the effects of the Interstate 40 Lane Reversal Plan on the evacuation of Wilmington and New Hanover County, North Carolina. In addition to the analysis of the effects of lane reversal, a side-by-side comparison of the CORSIM and VISSIM simulation models was performed on the highway network based on demand estimates provided by a demand study performed for the United States Army Corps of Engineers and the Federal Emergency Management Agency (FEMA). Analysis using CORSIM and VISSIM showed lane reversal to provide considerable capacity increases to traffic attempting to exit New Hanover County via Interstate 40, which had significantly increased throughput and decreased queues within New Hanover County in the event of large-scale evacuations.

Recent research in seasonal climate prediction has focused on combining multiple atmospheric General Circulation Models (GCMs) to develop multimodel ensembles. A new approach to combine multiple GCMs is proposed by analyzing the skill of candidate models contingent on the relevant predictor(s) state. To demonstrate this approach, we combine historical simulations of winter (December-February, DJF) precipitation and temperature from seven GCMs by evaluating their skill â represented by Mean Square Error (MSE) â over similar predictor (DJF Nino3.4) conditions. The MSE estimates are converted into weights for each GCM for developing multimodel tercile probabilities. A total of six multimodel schemes are considered that includes combinations based on pooling of ensembles as well as based on the long-term skill of the models. To ensure the improved skill exhibited by the multimodel scheme is statistically significant, we perform rigorous hypothesis tests comparing the skill of multimodels with individual modelsâ skill. The multimodel combination contingent on Nino3.4 show improved skill particularly for regions whose winter precipitation and temperature exhibit significant correlation with Nino3.4. Analyses of weights also show that the proposed multimodel combination methodology assigns higher weights for GCMs and lesser weights for climatology during El Nino and La Nina conditions. On the other hand, due to the limited skill of GCMs during neutral conditions over the tropical Pacific, the methodology assigns higher weights for climatology resulting in improved skill from the multimodel combinations. Thus, analyzing GCMsâ skill contingent on the relevant predictor state provide an alternate approach for multimodel combination such that years with limited skill could be replaced with climatology.

In this thesis, we present a study conducted on investigating the nature of damping matrix associated with multi degree of freedom simple shear building models. The various conventional methods of creating damping matrices in structures are summarized and numerical examples are used to illustrate the inconsistencies among them. Numerical examples are also used to illustrate the significance of non-zero off diagonal terms in the transformed damping matrix obtained after pre and post multiplication with mode shape matrix, i.e. the significance of non-classical nature of damping matrix in certain cases. The analytical study is followed by the description of a laboratory experiment that is developed to evaluate the validity of analytical results. The results from experimental studies of simple 2-DOF and 3-DOF shear building models, both with and without supplemental damping devices, are presented to validate the inconsistencies associated with the conventional methods of creating damping matrices in structures. It is also shown that the incorrect formulation of damping matrix results in highly incorrect responses. Several formulations for damping matrices are then proposed and their validity is evaluated by comparison with experimental results.

A macroscopic simulation tool is developed and tested in order to quantify the effects of short turn pockets on the sustainable service rate of a signalized intersection. Unlike the theoretical signal capacity, the sustainable service rate includes queue interaction effects and is thus influenced by blockage and spillback at the entrance to a short turn pocket. Previous research on the topic has focused either on the probability of spillback from a short turn pocket or the operation of a system with a single approach lane. No macroscopic model currently available has the ability to analyze throughput reductions due to short turn pocket effects on a multilane approach. The model described herein utilizes a series of flow and density restrictions on cells of varying sizes on the approach to the intersection. Results indicate sensitivity of the model to turn pocket spillback, blockage, saturation flow rate, pocket length, lane utilization, phase sequence, phase overlap, permitted phasing, and time-dependent demand. A phase optimization procedure is also described to help efficiently allocate green time for a given set of turn pocket lengths and turn movement percentages. Outputs from the model compare favorably to results generated using microsimulation software, and recommendations are made regarding additional model enhancements and testing needs.

Analysis of the construction load distribution during construction of multistory concrete buildings is critical for both construction safety and economy. Recent reduction of load factors used in design of the permanent structure has resulted in less strength availability in the construction stage and need for tools to better support shoring and reshoring analysis. Using the traditional simplified method to analyze loads in a concrete structure under construction, spreadsheet models have been developed which distribute load inputs chosen by the engineer. The models determine the vertical loads resisted by the following shoring systems: one set of shores with either two or three sets of reshores; two sets of shores with either one or two sets of reshores; or three sets of mechanical drophead shores. Analysis can be performed using either unfactored or factored loads and using either actual uniform loads or loads expressed as a proportion of slab dead load, D. Slab liftoff was then analyzed to prevent improper loading conditions during the construction cycle of multistory concrete buildings. The results of the models were validated by comparison with previously published shoring analysis. Lastly, a sensitivity analysis is performed to compare the loads supported by individual slabs and sets of shores in each model during the placement of upper floors.