Hot Mix Asphalt (HMA) overlay is a major rehabilitation treatment for the existing deteriorated pavements (both flexible and rigid pavements). Reflective cracking (RC) is the most common distress type appearing in the HMA overlays which structurally and functionally degrades the whole pavement structure, especially under high traffic volume. Although many studies have been conducted to identify the best performing RC mitigation technique, the level of success varies from premature failure to good performance in the field. In Florida, Asphalt Rubber Membrane Interlayers (ARMIs) have been used as a RC mitigation technique but its field performance has not been successful. In this study, the best performing means to mitigate RC in the overlays considering Florida’s special conditions have been investigated. The research methodology includes (1) extensive literature reviews regarding the RC mechanism and introduced mitigation options, (2) nationwide survey for understanding the current practice of RC management in the U.S., and (3) the development of decision trees for the selection of the best performing RC mitigation method. Extensive literature reviews have been conducted to identify current available RC mitigation techniques and the advantages and disadvantages of each technique were compared. Lesson learned from the collected case studies were used as input for the selection of the best performing RC mitigation techniques for Florida’s roads. The key input parameters in selecting optimum mitigation techniques are: 1) overlay characterization, 2) existing pavement condition, 3) base and subgrade structural condition, 4) environmental condition and 5) traffic level. In addition, to understand the current iv practices how reflective cracking is managed in each state, a nationwide survey was conducted by distributing the survey questionnaire (with the emphasis on flexible pavement) to all other highway agencies. Based on the responses, the most successful method of treatment is to increase the thickness of HMA overlay. Crack arresting layer is considered to be in the second place among its users. Lack of cost analysis and low rate of successful practices raise the necessity of conducting more research on this subject. Considering Florida’s special conditions (climate, materials, distress type, and geological conditions) and the RC mechanism, two RC mitigation techniques have been proposed: 1) overlay reinforcement (i.e. geosynthetic reinforcement) for the existing flexible pavements and 2) Stress Absorbing Membrane Interlayer (SAMI) for the existing rigid pavements. As the final products of this study, decision trees to select an optimum RC mitigation technique for both flexible and rigid pavements were developed. The decision trees can provide a detailed guideline to pavement engineer how to consider the affecting parameters in the selection of RC mitigation technique.

Uncertainty in geospatial data fusion is a major concern for scientists because society is increasing its use of geospatial technology and generalization is inherent to geographic representations. Limited research exists on the quality of results that come from the fusion of geographic data, yet there is extensive literature on uncertainty in cartography, GIS, and geospatial data. The uncertainties exist and are difficult to understand because data are overlaid which have different scopes, times, classes, accuracies, and precisions. There is a need for a set of tools that can manage uncertainty and incorporate it into the overlay process. This research explores uncertainty in spatial data, GIS and GIScience via three papers. The first paper introduces a framework for classifying and modeling error-bands in a GIS. Paper two tests GIS users' ability to estimate spatial confidence intervals and the third paper looks at the practical application of a set of tools for incorporating uncertainty into overlays. The results from this research indicate that it is hard for people to agree on an error-band classification based on their interpretation of metadata. However, people are good estimators of data quality and uncertainty if they follow a systematic approach and use their average estimate to define spatial confidence intervals. The framework and the toolset presented in this dissertation have the potential to alter how people interpret and use geospatial data. The hope is that the results from this paper prompt inquiry and question the reliability of all simple overlays. Many situations exist in which this research has relevance, making the framework, the tools, and the methods important to a wide variety of disciplines that use spatial analysis and GIS. / Ph. D.

No / The FIRE trust and reputation model is a de-centralized trust model that can be applied for trust management in unstructured Peer-to-Peer (P2P) overlays. The FIRE model does not, however, consider malicious activity and possible collusive behavior in nodes of network and it is therefore susceptible to collusion attacks. This investigation reveals that FIRE is vulnerable to lying and cheating attacks and presents a trust management approach to detect collusion in direct and witness interactions among nodes based on colluding node's history of interactions. A witness ratings based graph building approach is utilized to determine possibly collusive behavior among nodes. Furthermore, various interaction policies are defined to detect and prevent collaborative behavior in colluding nodes. Finally a multidimensional trust model FIRE+ is devised for avoiding collusion attacks in direct and witness based interactions. The credibility of the proposed trust management scheme as an enhancement of the FIRE trust model is verified by extensive simulation experiments.

No description available.

Efficient handoff algorithms cost-effectively enhance the capacity and Quality of Service (QoS) of cellular systems. This research presents novel approaches for the design of high performance handoff algorithms that exploit attractive features of several existing algorithms, provide adaptation to dynamic cellular environment, and allow systematic tradeoffs among different system characteristics. A comprehensive foundation of handoff and related issues of cellular communications is given. The tools of artificial intelligence utilized in this research, neural networks and fuzzy logic, are introduced. The scope of existing simulation models for macrocellular and microcellular handoff algorithms is enhanced by incorporating several important features. New simulation models suitable for performance evaluation of soft handoff algorithms and overlay handoff algorithms are developed. Four basic approaches for the development of high performance algorithms are proposed and are based on fuzzy logic, neural networks, unified handoff candidate selection, and pattern classification. The fuzzy logic based approach allows an organized tuning of the handoff parameters to provide a balanced tradeoff among different system characteristics. The neural network based approach suggests neural encoding of the fuzzy logic systems to simultaneously achieve the goals of high performance and reduced complexity. The unified candidacy based approach recommends the use of a unified handoff candidate selection criterion to select the best handoff candidate under given constraints. The pattern classification based approach exploits the capability of fuzzy logic and neural networks to obtain an efficient architecture of an adaptive handoff algorithm. New algorithms suitable for microcellular systems, overlay systems, and systems employing soft handoff are described. A basic adaptive algorithm suitable for a microcellular environment is proposed. Adaptation to traffic, interference, and mobility has been superimposed on the basic generic algorithm to develop another microcellular algorithm. An adaptive overlay handoff algorithm that allows a systematic balance among the design parameters of an overlay system is proposed. Important considerations for soft handoff are discussed, and adaptation mechanisms for new soft handoff algorithms are developed. / Ph. D.

A portraiture study was conducted with four children enrolled in various grades of a rural Virginia elementary school. . Purposeful sampling was used as a selection tool, and all students were participants of the Title I program, unsuccessfully discontinued from the Reading Recovery program, and were tested as field dependent, a cognitive characteristic, using the Children's Embedded Figures Test created by Witkin, et al (1971). These participants were observed within a classroom setting, a small group setting, and in a one-on-one setting. Interviews offered the opportunity to investigate the students' feelings and attitudes towards using the overlays. Field notes, unaided observations, participant observations were gathered, and interviews were conducted with the students, as well as with the reading specialist, the teachers, and the administrator of the school. Further data was gained from historical records from the school and evaluative tools used within the classroom, on a periodic basis. Outcomes of this study focus on the process of using colored overlays with these participants, their self-efficacy their feelings about using the tool, how the faculty perceives this tool, and additional implications with regards to field dependence and colored overlays within the classroom. / Ph. D.

The objective of this study is to evaluate the bond durability of an epoxy-based polymer concrete wearing surface bonded to aluminum bridge decks. In the bridge design, an aluminum alloy bridge deck is used with a polymer concrete wearing surface. A modified mixed mode flexure fracture test was developed to assess the bond durability of specimens aged in the following environmental conditionings: 30°C [86°F], 98% RH; 45°C [113°F], 98% RH; 60°C [140°F], 98% RH; freezing and thawing; salt (NaCl) water soak; and 60°C [140°F], dry. The exposure times varied from none to twelve months. The critical strain energy release rate (Gc) of the bond was determined using a compliance technique. In spite of considerable scatter in the data, the results suggested that the interfacial bond toughness had been degraded by exposure conditions. The aging appeared to affect the polymer concrete overlay (silica aggregates/epoxy bond) as well. Fracture analysis and finite element modeling were completed for linear elastic behavior. Analytical and numerical solutions were in reasonably good agreement. Characterization of the bridge components and failure specimens were accomplished using analytical measurements including thermal gravimetric analysis (TGA), differential scanning calorimetry (DSC), and dynamic mechanical analysis (DMA). Techniques employed in the surface analysis included x-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). / Master of Science

The highway network in the United States, specifically reinforced concrete bridges, is deteriorating at a rapid rate. It is known that chloride-induced corrosion of the reinforcing steel is one of the major causes of the deterioration of concrete bridge decks. Numerous bridge deck protection and overlay systems have been developed to reduce the deterioration rate caused by chloride-induced corrosion. This study investigated the service life of untreated concrete bridge decks and four bridge deck overlay systems: low-slump-dense concrete (LSDC), latex-modified concrete (LMC), micro-silica concrete (MSC), and preformed membranes with hot-mix asphalt overlays (PM-HMA). The research plan consisted of organizing and analyzing data obtained in a 1991 field survey of 52 bridges from various locations in the nation. The field survey was conducted to gather information on existing conditions of untreated and rehabilitated bridge decks. Corrosion measurements were taken to assess the performance of each technique. Statistical models that predict the percent of deterioration on a bridge deck and the corrosion rate for each technique were developed from the field survey data. The components of a deterioration model were combined to define the service life for each bridge deck overlay system and for untreated concrete bridge decks. Other service life estimates for untreated bridge decks and bridge deck overlay systems were also compared. Based on the statistical analysis and service life comparisons, a service life estimate was recommended for predicting the service life for three of the bridge deck overlay systems. / Master of Science

Two different asphalt concrete systems were examined in this research study. The existing system, consistent with current timber bridge construction practice, uses a preformed waterproofing membrane placed on a preservative treated wood deck overlaid with a bituminous concrete wearing surface. The second system consists of a treated wood deck overlaid with a base course of bituminous concrete, a waterproofing membrane, and a bituminous concrete wearing surface. The testing regime used in this research to evaluate watertightness and bond performance incorporated three parameters: three waterproofing membranes, two wood preservative treatments, and two environmental degradation conditions induced by temperature cycling in a moisture saturated condition. Control groups were evaluated for each study parameter and duplicate specimens were prepared and tested for each of the study parameters. A total of 160 specimens were constructed and tested. Watertightness of each system was determined by measuring the electrical impedance across a test specimen perpendicular to the direction of bond orientation in the pavement. The bond strength between each material of the paving systems was assessed using a shear test apparatus designed and built for this study. In addition to the laboratory constructed specimens, three drilled cores were taken from a bridge located on Creekside Drive in East Pennsboro Township, Pennsylvania. The deck was constructed using the new design proposed in this research and each core was tested for watertightness and bond strength. Results of watertightness testing indicated that low temperature environments appear to be most detrimental to system integrity in both the existing and proposed paving system configurations examined in this research. In general, each membrane appeared to perform equally well in the proposed paving system configuration as well as with all of the wood preservative treatments used in the existing pavement system. Bond strength between asphalt and wood with no membrane was observed to be nonexistent whether or not any preservative treatment was present. The placement of a membrane between these two layers did, however, result in a significant increase in bond strength because each membrane tested was able to adhere to the wood base better than the asphalt overlay. This gain is strength was significantly offset when petroleum solvent based preservative treatments were present in the wood substrate. Protectowrap M400 membrane performed slightly better than the other membranes when used with untreated wood, but all of the membranes performed equally when preservative treatments were present. The highest interlayer bond strengths (asphalt/asphalt or asphalt/wood) observed in this research occurred when asphalt concrete surface material was placed directly on top of asphalt concrete base material, however the addition of a membrane between the asphalt lifts consistently reduced this strength. The results of bond testing indicate that the proposed system will perform better in terms of shoving in the pavement overlay. Based on bond test results of cores taken from the Creekside Drive bridge, it appears that a shear strength greater than 25 psi after 200 low temperature exposure cycles will provide acceptable paving system performance in a low temperature (0-40ºF) environment. / Master of Science

Yes / We thank Professors Evans and Wilkins for their interest in our systematic review.(1) We have reached the same conclusion as previous systematic reviews published in 2008(2) and 2014(3) and a review prepared for the New Zealand Ministry for Health in 2009.(4) Even the ‘alternative systematic review’ prepared by Professors Evans and Allen about which we have significant misgivings concludes that ‘larger and rigorous randomised controlled trials of interventions for visual stress are required’.(5) / A response to Professors Evans and Wilkins regarding the systematic review: Griffiths PG, Taylor RH, Henderson LM and Barrett BT (2016) The effect of coloured overlays and lenses on reading: a systematic review of the literature. Ophthalmic & Physiological Optics. 36: 519–544.