This thesis research investigated the predictive performance of pavement marking retroreflectivity measured under various conditions of continuous wetting. The researcher compared nighttime detection distance of pavement markings in simulated rain conditions and the retroreflectivity of the same pavement markings in several continuous wetting conditions. Correlation analyses quantified the predictive performance of the resulting retroreflectivity values from the continuous wetting conditions. The researcher measured the retroreflectivity of 18 pavement marking samples under 14 different conditions. The American Society for Testing and Materials (ASTM) has three standards for measuring the retroreflectivity of pavement markings under: dry (E-1710), recovery (E-2177), and continuous wetting conditions (E-2176). Using three ASTM standard conditions resulted in three sets of retroreflectivity data, and variations of the continuous wetting standard produced an additional 11 sets of continuous wetting condition data. The researcher also incorporated detection distance values measured for the same 18 pavement marking samples under three different simulated rainfall conditions at night. The three conditions included: high (0.87 in/hr), medium (0.52 in/hr), and low (0.28 in/hr) flow rates, these rates were to simulate typical rainfall rates in the state of Texas. The correlation analyses measures the linear relationship as well as the logarithmic relationship between the detection distance and the retroreflectivity of the pavement markings. A pavement markings' retroreflectivity is typically used as a detection distance performance indicator, therefore a high degree of correlation between retroreflectivity and detection distance would be desired. A high degree of correlation would indicate that a measured retroreflectivity value of a pavement marking would provide a good indication of the expected detection distance. The researcher conducted analyses for several subgroups of the pavement markings based on the markings type or characteristics. Dry, recovery, and all the continuous wetting retroreflectivity data were correlated to the detection distances. Correlation values found during this thesis research did not show a high degree of correlation for most of the subgroups analyzed. This indicates that measured retroreflectivity would not provide very good predictive performance of the pavement markings detection distance in rainy conditions.

Thesis (Ph.D.)--Ohio University, June, 2009. / Release of full electronic text on OhioLINK has been delayed until June 1, 2010. Includes bibliographical references (leaves 184-194)

Thesis (Ph.D.)--Ohio University, June, 2009. / Title from PDF t.p. Release of full electronic text on OhioLINK has been delayed until June 1, 2010. Includes bibliographical references (leaves 184-194)

Thesis (Ph. D.)--Institute of Paper Chemistry, 1960. / Includes bibliographical references (p. 100-102).

Thesis (Ph. D.)--Institute of Paper Chemistry, 1974. / Includes bibliographical references (p. 114-117).

Thesis (Ph. D.)--Institute of Paper Chemistry, 1963. / Includes bibliographical references (leaves 126-131).

Thesis (Ph. D.)--Institute of Paper Chemistry, 1947. / Bibliography: leaves 67-69.

Colorimetric litmus tests such as pH paper have enjoyed wide commercial success due to their inexpensive production and exceptional ease of use. However, expansion of colorimetry to new sensing paradigms is challenging because macroscopic color changes are seldom coupled to arbitrary differences in the physical/chemical properties of a system. In this thesis I present in detail the development of Wetting in Color Technology, focusing primarily on its application as an inexpensive and highly selective colorimetric indicator for organic liquids. The technology exploits chemically-encoded inverse-opal photonic crystals to control the infiltration of fluids to liquid-specific spatial patterns, projecting minute differences in liquids’ wettability to macroscopically distinct, easy-to-visualize structural color patterns. It is shown experimentally and corroborated with theoretical modeling using percolation theory that the high selectivity of wetting, upon-which the sensitivity of the indicator relies, is caused by the highly symmetric structure of our large-area, defect-free \(SiO_2\) inverse-opals. The regular structure also produces a bright iridescent color, which disappears when infiltrated with liquid naturally coupling the optical and fluidic responses. Surface modification protocols are developed, requiring only silanization and selective oxidation, to facilitate the deterministic design of an indicator that differentiates a broad range of liquids. The resulting tunable, built-in horizontal and vertical chemistry gradients allow the wettability threshold to be tailored to specific liquids across a continuous range, and make the readout rely only on countable color differences. As wetting is a generic fluidic phenomenon, Wetting in Color technology could be suitable for applications in authentication or identification of unknown liquids across a broad range of industries. However, the generic nature of the response also ensures chemical non-specificity. It is shown that combinatorial measurements from an array of indicators add a degree of chemical specificity to the platform, which can be further improved by monitoring the drying of the inverse-opal films. While colorimetry is the central focus of this thesis, applications of this platform in encryption, fluidics and nanofabrication are also briefly explored. / Engineering and Applied Sciences

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