Doctor of Philosophy / Department of Civil Engineering / Mustaque A. Hossain / Tack coat is a thin layer of asphaltic material used to bind a newly-placed lift of hot-mix asphalt (HMA) pavement to a previously-placed lift or a new HMA overlay/inlay and existing pavement. The purpose of a tack coat is to ensure that a proper bond occurs so that traffic loads are carried by the entire HMA structure. Proper bonding exists when HMA layers act as a monolithic structure, transferring loads from one layer to the next. This depends on appropriate selection of tack coat material type and application rate, and is essential to prevent slippage failure and premature cracking in the wearing surface. This study focuses on development of a three-dimensional finite element (FE) model of HMA pavement structure in order to assess HMA interface bonding. The FE model was constructed using commercially available ABAQUS software to simulate an Accelerated Pavement Testing (APT) experiment conducted at the Civil Infrastructure Systems Laboratory (CISL) at Kansas State University. Mechanistic responses measured in the CISL experiment, such as localized longitudinal strain at the interface, were used to calibrate the FE model. Once calibrated, the model was used to predict mechanistic responses of the pavement structure by varying the tack coat property to reflect material characteristics of each application. The FE models successfully predicted longitudinal strains that corresponded to APT results.

Published Article / The current debate within the ASGISA and NEPAD policy structures of the South African Government is to enhance E-service delivery via Information and Communication Technologies (ICT) for all citizens. This paper deals with the problem how ICT in governance may be constructed to facilitate greater accountability, transparency and reducing corruption through better financial, public information management, procurement and administrative systems. South Africans especially in rural areas have a limited access to ICT. The main barriers to ICT access relate to high cost of Internet access, connectivity problems, lack of technical skills to support maintenance and low number of computers with Internet connectivity at schools, libraries and other public places.

Résumé : La technologie des armatures en matériaux composites de polymères renforcés de fibre (PRF) reste relativement récente (moins de 20 ans) et souffre d’une moins bonne réputation en termes de durabilité, ce qui tend à freiner son acceptation par les professionnels du secteur. Les travaux présentés dans ce mémoire ont pour but d’étudier les effets de l’humidité et de l’alcalinité sur les performances mécaniques et thermomécaniques de barres d’armature en PRF. Si de nos jours l’évolution des propriétés des armatures de PRF a été largement étudiée par différents chercheurs, nous n’avons que peu d’informations sur les modes de dégradation qui entrainent ces pertes de performances. Le but des travaux entrepris dans ce mémoire est de trouver des pistes d’investigation pour la compréhension de ces mécanismes de dégradation qui pourraient éventuellement par la suite être reprises dans le cadre de travaux de thèse. Les travaux qui ont été entrepris s’articulent autour de deux projets. Le premier s’intéresse à l’étude du vieillissement accéléré de barres de polymère renforcé de fibres de verre (PRFV) de différents diamètres et soumis à un environnement humide. Le second s’intéresse à l’étude de barres de PRFV et de polymère renforcé de fibres de basalte (PRFB) de même diamètre soumis à un environnement alcalin qui simule le milieu interstitiel du béton. / Abstract : The FRP rebars technology remains relatively recent and suffers from a bad reputation in terms of durability which slows its acceptation among the professionals of the construction field. The aim of the work presented in this essay is to study the effects of moisture and alkalinity on the mechanical and thermo mechanical performances of FRP rebars. Nowadays, the progressions of FRP performances have been widely studied by different researchers but we still have few knowledge about the modes of degradation which lead to performance losses. The final goal of this work is to find investigation trails for the understanding of those degradation mechanisms which could possibly be taken over as part of a thesis work. The work is divided into two projects. The first one is the study of accelerated aging of glass fibers reinforced polymer (GFRP) rebars, of different diameters, conditioned in a moist environment. The second one concerns the behavior of GFRP and basalt fibers reinforced polymer (BFRP) rebars, of same diameter, conditioned in an alkaline environment which simulates the interstitial solution of concrete.

This dissertation considers the composite saddle-point (CSP) problem which is motivated by real-world applications in the areas of machine learning and image processing. Two new accelerated algorithms for solving composite saddle-point problems are introduced. Due to the two-block structure of the CSP problem, it can be solved by any algorithm belonging to the block-decomposition hybrid proximal extragradient (BD-HPE) framework. The framework consists of a family of inexact proximal point methods for solving a general two-block structured monotone inclusion problem which, at every iteration, solves two prox sub-inclusions according to a certain relative error criterion. By exploiting the fact that the two prox sub-inclusions in the context of the CSP problem are equivalent to two composite convex programs, the first part of this dissertation proposes a new instance of the BD-HPE framework that approximately solves them using an accelerated gradient method. It is shown that this new instance has better iteration-complexity than the previous ones. The second part of this dissertation introduces a new algorithm for solving a special class of CSP problems. The new algorithm is a special instance of the hybrid proximal extragradient (HPE) framework in which a Nesterov's accelerated variant is used to approximately solve the prox subproblems. One of the advantages of the this method is that it works for any constant choice of proximal stepsize. Moreover, a suitable choice of the latter stepsize yields a method with the best known (accelerated inner) iteration complexity for the aforementioned class of saddle-point problems. Experiment results on both synthetic CSP problems and real-world problems show that the two method significantly outperform several state-of-the-art algorithms.

Thesis (MEng)--University of Stellenbosch, 2000. / ENGLISH ABSTRACT: Accelerated pavement testing (APT) is the application of a wheel loading, to a prototype or actual layered, structural pavement system to determine pavement response and performance under controlled, accelerated accumulation of damage in a compressed time period. It is a tool used for the evaluation of performance of new pavement materials, distress mechanisms, pavement distress, and selection of rehabilitation strategies. In this study, the research work that was done in Jacksboro, Texas (USA) with the third-scale Model Mobile Load Simulator (MMLS3) as part of the APT programme of the Texas Department of Transportation (TxDOT) is presented. The primary objective was to evaluate the performance ofthe different asphalt concrete (AC) materials (Dustrol and Remixer) used on highway US 281, in terms of rutting and distress due to wet trafficking. The other objective was to investigate the difference in rutting between the MMLS3 and the full-scale Texas Mobile Load Simulator (TxMLS). The scope of the study included fieldwork, laboratory work and theoretical analysis. On average, the performance of the layer from the Dustrol process was found to be poorer than that of the Remixer process. The Dustrol process was more susceptible to moisture damage and less resistant to permanent deformation compared to the Remixer process. The MMLS3 and TxMLS permanent deformations in the upper 90 mm surface layers correlated well in terms of the respective vertical stresses imposed by the two APT devices, after allowing for the difference in environmental conditions during trafficking. Overall, the study demonstrated that the MMLS3, used in conjunction with nondestructive field and laboratory testing, is a significant cost-effective APT device that can be used for evaluating the response and performance of the (surface) layers of full-scale, in-service pavements. / AFRIKAANSE OPSOMMING: Versnelde Plaveisel Toetsing bestaan uit die gebruik van 'n wiellas op 'n prototipe of 'n bestaande gelaagde plaveiselstruktuur om die plaveiselgedrag onder beheerde en versnelde toename in skade in 'n verkorte periode te bepaal. Dit word gebruik om die gedrag van nuwe plaveiselmateriale, swigtingsmeganismes, plaveiselswigting en die keuse van rehabilitasie strategieë te evalueer. Die navorsingswerk met die derde skaal Model Mobile Load Simulator (MMLS3) wat onderneem is in Jacksboro, Texas (VSA), en deel uitmaak van die Versnelde Plaveisel Toetsingsprojek van die Texas Departement van Vervoer (TxDOT), word uiteengesit. Die hoofdoel van die studie was om die gedrag van twee verskillende asfaltmateriale, naamlik Dustrol en Remixer, wat gebruik is op die US 281-snelweg, in terme van sporing en swigting as gevolg van nat belastingstoestande te evalueer. 'n Verdere doelstelling was om die verskil in die gemete sporing tussen die MMLS3 en die volskaal Texas Mobile Load Simulator (TxMLS) te ondersoek. Die studie het veld- en laboratoriumtoetse en teoretiese analise behels. Die gedrag van die Dustrol laag is oor die algemeen swakker as die Remixer lae. Die Dustrol laag, in vergelyking met die Remixer lae, is meer vatbaar vir vogskade en spoor makliker. Nadat die invloed van verskillende omgewingstoestande gedurende asbelasting inaggeneem is, korreleer die sporing vir die MMLS3 en die TxMLS in die lae van die boonste 90mm van die plaveisel goed in terme van die vertikale spannings soos opgewek deur die twee toetstoestelle. In die geheel word bewys dat die MMLS3 tesame met nie-destruktiewe veld- en laboratoriumtoetse 'n belangrike koste-effektiewe versnelde plaveisel toetstoestel is, wat aangewend kan word in die evaluasieproses van die gedrag van (oppervlak) lae van volskaalse plaveisels in gebruik.

This thesis reports on the research outcome of corrosion mechanism and corrosion rate of mild steel in different environments (saline, alkaline solutions and concrete media) using potentiodynamic polarization technique. The study also included the effect of corrosion on bond strength between reinforcing steel and concrete using pull-out test. Corrosion of mild steel and 316L stainless steel with different surface conditions in 1, 3 and 5% saline (NaCl + Distilled water) was investigated. Specimens ground with 200 and 600 grit silicon carbide grinding paper as well as 1μm surface finish (polished with 1μm diamond paste) were tested. In case of mild steel specimens, reduction in surface roughness caused increase in corrosion rate, while in 316L stainless steel corrosion rate decreased as the surface roughness improved. Metallographic examination of corroded specimens confirmed breakdown of passive region due to pitting corrosion. Corrosion of mild steel was also investigated in alkaline solution (saturated calcium hydroxide, pH =12.5) contaminated with 1, 3 and 5% saline. A series of corrosion experiments were also conducted to examine the efficiency of various concentrations of calcium nitrite (CN) on corrosion behaviour of both as-received and polished mild steel in alkaline solution containing 3% saline after 1 hour and 28 days of exposure. Corrosion rate was higher for the as-received than polished mild steel surface under the same testing conditions in NaCl alkaline solution with and without nitrites due to the effect of surface roughness. Morphology investigation of mild steel specimens in alkaline solution ii containing chlorides and nitrites showed localized pits even at nitrite concentration equal to chloride concentration. Corrosion of steel bars embedded in concrete having compressive strengths of 20, 30 and 46MPa was also investigated. The effect of 2 and 4% CN by weight of cement on corrosion behaviour of steel bar in low and high concrete strengths specimens were also studied. All reinforced concrete specimens were immersed in 3% saline solution for three different periods of 1, 7 and 15 days. In order to accelerate the chemical reactions, an external current of 0.4A was applied. Corrosion rate was measured by retrieving electrochemical information from polarization tests. Pull-out tests of reinforced concrete specimens were then conducted to assess the corroded steel/concrete bond characteristics. Experimental results showed that corrosion rate of steel bars and bond strength were dependent on concrete strength, amount of CN and acceleration corrosion period. As concrete strength increased from 20 to 46MPa, corrosion rate of embedded steel decreased. First day of corrosion acceleration showed a slight increase in steel/concrete bond strength, whereas severe corrosion due to 7 and 15 days corrosion acceleration significantly reduced steel/concrete bond strength. Addition of only 2% CN did not give corrosion protection for steel reinforcement in concrete with 20MPa strength at long time of exposure. However, the combination of good quality concrete and addition of CN appear to be a desirable approach to reduce the effect of chloride induced corrosion of steel reinforcement. At less time of exposure, specimens without CN showed higher bond strength in both concrete mixes than those with CN. After 7 days of corrosion acceleration, the higher concentration of CN gave higher bond strength in both concrete mixes. The same trend was observed at 15 days of corrosion acceleration except for the specimen with 20MPa compressive strength and 2% CN which recorded the highest deterioration in bond strength.

This report aims to increase the scientific knowledge about long-term prospects for the adhesive and adhesive joints for bonding of stainless steels. The effects of water, temperature and chemicals on the adhesive and adhesive joints are investigated. Stainless steel plates are pretreated with a primer and isopropanol, there after joined together with single lap modeling. The strength of the joint is tested with a tensile test and additionally a watertightness test is performed to determine if the joints are watertight. For this project three versions of stainless steels is used and two different technologies of two- part adhesives, silicone and silane-modified polymer and one technology of tape, a double coated acrylic foam tape are tested. The result shows that all the adhesives fails cohesively and that tape fails partly adhesively. Result shows that all tests are affected by water, temperature and chemicals on different levels but tape is affected the most with a minimum of 40% loss in shear strength. Watertightness test shows that aged tape joints are not watertight. The polymer shows no signs of decreasing in shear strength and is watertight, but does become more viscous by aging. The report shows that a possible combination of adhesive and pretreatment that can withstand the effects of water, temperature and chemicals is found. The polymer presents a possibility to bond stainless steel with a simple pretreatment. Tape didn’t pass the test in a suitable way but presents opportunities if a sufficient pretreatment can be found.

Doctor of Philosophy / Department of Educational Leadership / Sarah J. Fishback / This study measured levels of conditions eliciting intrinsic motivation to learn and examined the correlation of those measures with learner-perceived level of learning. Acquired from adult learners participating in one Midwestern University’s cohort-based degree programs, data helped determine the extent to which learners perceived the presence of four conditions—inclusion, attitude, meaning, and competence—in both classroom and out-of-classroom learning environments. Additionally, the data helped determine which environment and specific conditions most closely correlated with learner-perceived level of current learning; and provided insight into experiences adult learners found positively or negatively impacting motivation to learn. Surveys were administered in-person to 137 of 150 students within 13 randomly selected cohorts. The survey instrument included a single overall learning attitudinal statement, two Likert scales (classroom and out-of-classroom) each comprised of subscales (inclusion, attitude, meaning, and competence) operationalizing the Motivational Framework for Culturally Responsive Teaching (Framework), a brief demographic section, and a concluding open-ended question regarding experiences impacting motivation to learn. The study used non-parametric analysis to examine dependent variables, motivation conditions, with respect to independent variables; age, gender, race, and degree-level. Additionally, non-parametric analysis examined correlation between condition measures and learner-perceived overall learning. Significant differences were found in two demographic categories. Underrepresented race/ethnicity students (as a combined category) rated overall out-of-classroom conditions higher than predominant race/ethnicity students; and, associate-level students rated classroom conditions lower than bachelors and masters-level students. Significant differences also occurred in subscales. Female students rated classroom attitude conditions higher than males; underrepresented students rated classroom attitude and competence, and out-of-classroom attitude, meaning, and competence, higher than predominant students; associates-level students rated classroom inclusion lower than both bachelors and masters-level students; and both associates and masters-level students rated classroom competence lower than bachelors-level students. All conditions, in both environments (classroom and out-of-classroom), were significantly correlated with learner-perceived level of learning; and the classroom scale demonstrated considerably stronger correlation than did the out-of-classroom scale. Of all subscales, both classroom and out-of-classroom meaning demonstrated the strongest correlation with learner-perceived level of learning. Forty-eight respondents (35% of sample) offered responses to the survey’s concluding statement. Of those respondents offering comments in regard to classroom motivation, instructor characteristics were most often noted. And, of those commenting on out-of-classroom motivation, team formulation and characteristics were predominant. Through the creation of the Motivation Conditions in Learning Instrument™, this study produced benchmark measures for each Framework condition experienced in both cohort-based classrooms and out-of-classroom team learning; identified differences in measures across demographic categories; and identified correlation of measures with learner-perceived level of learning. Finally, the study provided insight into learner experiences impacting motivation to learn.

Master of Arts / Department of Statistics / Paul Nelson / There are two important statistical models for multivariate survival analysis, proportional hazards(PH) models and accelerated failure time(AFT) model. PH analysis is most commonly used multivariate approach for analysing survival time data. For example, in clinical investigations where several (known) quantities or covariates, potentially affect patient prognosis, it is often desirable to investigate one factor effect adjust for the impact of others. This report offered a solution to choose appropriate model in testing covariate effects under different situations. In real life, we are very likely to just have limited sample size and censoring rates(people dropping off), which cause difficulty in statistical analysis. In this report, each dataset is randomly repeated 1000 times from three different distributions (Weibull, Lognormal and Loglogistc) with combination of sample sizes and censoring rates. Then both models are evaluated by hypothesis testing of covariate effect using the simulated data using the derived statistics, power, type I error rate and covergence rate for each situation. We would recommend PH method when sample size is small(n<20) and censoring rate is high(p>0.8). In this case, both PH and AFT analyses may not be suitable for hypothesis testing, but PH analysis is more robust and consistent than AFT analysis. And when sample size is 20 or above and censoring rate is 0.8 or below, AFT analysis will have slight higher convergence rate and power than PH, but not much improvement in Type I error rates when sample size is big(n>50) and censoring rate is low(p<0.3). Considering the privilege of not requiring knowledge of distribution for PH analysis, we concluded that PH analysis is robust in hypothesis testing for covariate effects using data generated from an AFT model.

In order to complete degrees faster, many nontraditional students enroll in Accelerated Learning (AL) programs where they often use communication software or devices, also called information communication technology (ICT). ICT literacy is the ability to use ICT appropriately to solve information problems. Gaps in ICT literacy can frustrate nontraditional students and distract them from learning course content. Due to AL programs` fast pace, there is little opportunity for students and educators to discover and fill ICT literacy gaps. Millions of nontraditional students enroll in programs designed for traditional students. Identifying ICT literacy gaps for students can help educators address specific academic needs. Identifying and bridging ICT literacy gaps is essential in preparing all students to succeed in the information age. While the mission of the National Higher Education ICT Initiative includes addressing the ICT literacy gaps of both traditional and nontraditional students, little effort or research exists to date, which examines the ICT literacy gap of nontraditional students. This lack of research makes it more difficult for institutions to recognize the issue of nontraditional students` ICT literacy gaps. This lack of research also makes it more difficult for institutions to address effectively these ICT literacy gaps. The goal of this research was to compare the ICT literacy gaps of traditionally aged students in traditional programs to the ICT literacy gaps of nontraditional students in AL programs and to help determine if nontraditional students in AL programs have unique ICT literacy gaps that warrant identification and remediation. This study expands the body of knowledge concerning ICT literacy gaps of nontraditional students in AL programs.