Matching Items (27)
Filtering by
- All Subjects: engineering
- All Subjects: psychology
Description
Alkali-activated aluminosilicates, commonly known as "geopolymers", are being increasingly studied as a potential replacement for Portland cement. These binders use an alkaline activator, typically alkali silicates, alkali hydroxides or a combination of both along with a silica-and-alumina rich material, such as fly ash or slag, to form a final product with properties comparable to or better than those of ordinary Portland cement. The kinetics of alkali activation is highly dependent on the chemical composition of the binder material and the activator concentration. The influence of binder composition (slag, fly ash or both), different levels of alkalinity, expressed using the ratios of Na2O-to-binders (n) and activator SiO2-to-Na2O ratios (Ms), on the early age behavior in sodium silicate solution (waterglass) activated fly ash-slag blended systems is discussed in this thesis. Optimal binder composition and the n values are selected based on the setting times. Higher activator alkalinity (n value) is required when the amount of slag in the fly ash-slag blended mixtures is reduced. Isothermal calorimetry is performed to evaluate the early age hydration process and to understand the reaction kinetics of the alkali activated systems. The differences in the calorimetric signatures between waterglass activated slag and fly ash-slag blends facilitate an understanding of the impact of the binder composition on the reaction rates. Kinetic modeling is used to quantify the differences in reaction kinetics using the Exponential as well as the Knudsen method. The influence of temperature on the reaction kinetics of activated slag and fly ash-slag blends based on the hydration parameters are discussed. Very high compressive strengths can be obtained both at early ages as well as later ages (more than 70 MPa) with waterglass activated slag mortars. Compressive strength decreases with the increase in the fly ash content. A qualitative evidence of leaching is presented through the electrical conductivity changes in the saturating solution. The impact of leaching and the strength loss is found to be generally higher for the mixtures made using a higher activator Ms and a higher n value. Attenuated Total Reflectance-Fourier Transform Infrared Spectroscopy (ATR-FTIR) is used to obtain information about the reaction products.
ContributorsChithiraputhiran, Sundara Raman (Author) / Neithalath, Narayanan (Thesis advisor) / Rajan, Subramaniyam D (Committee member) / Mobasher, Barzin (Committee member) / Arizona State University (Publisher)
Created2012
Description
The alkali activation of aluminosilicate materials as binder systems derived from industrial byproducts have been extensively studied due to the advantages they offer in terms enhanced material properties, while increasing sustainability by the reuse of industrial waste and byproducts and reducing the adverse impacts of OPC production. Fly ash and ground granulated blast furnace slag are commonly used for their content of soluble silica and aluminate species that can undergo dissolution, polymerization with the alkali, condensation on particle surfaces and solidification. The following topics are the focus of this thesis: (i) the use of microwave assisted thermal processing, in addition to heat-curing as a means of alkali activation and (ii) the relative effects of alkali cations (K or Na) in the activator (powder activators) on the mechanical properties and chemical structure of these systems. Unsuitable curing conditions instigate carbonation, which in turn lowers the pH of the system causing significant reductions in the rate of fly ash activation and mechanical strength development. This study explores the effects of sealing the samples during the curing process, which effectively traps the free water in the system, and allows for increased aluminosilicate activation. The use of microwave-curing in lieu of thermal-curing is also studied in order to reduce energy consumption and for its ability to provide fast volumetric heating. Potassium-based powder activators dry blended into the slag binder system is shown to be effective in obtaining very high compressive strengths under moist curing conditions (greater than 70 MPa), whereas sodium-based powder activation is much weaker (around 25 MPa). Compressive strength decreases when fly ash is introduced into the system. Isothermal calorimetry is used to evaluate the early hydration process, and to understand the reaction kinetics of the alkali powder activated systems. A qualitative evidence of the alkali-hydroxide concentration of the paste pore solution through the use of electrical conductivity measurements is also presented, with the results indicating the ion concentration of alkali is more prevalent in the pore solution of potassium-based systems. The use of advanced spectroscopic and thermal analysis techniques to distinguish the influence of studied parameters is also discussed.
ContributorsChowdhury, Ussala (Author) / Neithalath, Narayanan (Thesis advisor) / Rajan, Subramanium D. (Committee member) / Mobasher, Barzin (Committee member) / Arizona State University (Publisher)
Created2013
Description
The relationship between video games and education is something that has been studied extensively in academia. Based upon these studies a new concept was created, gamification. Gamification is the next step in video game research to analyze why video games enhance learning. The interest and research into this concept have developed so much so that it has become its own topic area for research. This study is looking to analyze the effect that gamification has on not only learning, but also self-efficacy. Through a choose your own adventure game, the knowledge and self-efficacy of participants will be examined to observe the differences when learning difficult engineering concepts with and without gamification. It is expected that participants that experienced training through gamification will demonstrate deeper learning and higher self-efficacy than trained through a video. Furthermore, it is anticipated that some video trained participants’ self-efficacy will increase; however, their comprehension will be less than participants trained through gamification. The results of this study can help promote the interest in researching gamification and education, while influencing educators to corporate gamification elements when designing their courses. Moreover, this study continued through adaptation and integration into a statics forces class, investigated if the same results can be found within a classroom setting.
ContributorsKanechika, Amber (Author) / Craig, Scotty (Thesis director) / Roscoe, Rod (Committee member) / Engineering Programs (Contributor) / Barrett, The Honors College (Contributor)
Created2020-05
Description
The relationship between user experience, learning, and psychology is complex. There are many rules and concepts that guide experience design. It is likely that some of the guidance is valid whereas other guidance is not. This explores some of that guidance and evaluates how they are linked to learning. Do the guidance’s made 25, 50, 100 years ago still hold true today? Additionally, the psychological background behind the way someone holds memory is important. Knowing how information is stored and processed helps educators provide the best learning experience possible. With an eye toward perception and cognition, this paper examines the relevance of the various pieces of guidance. The results suggest that, overall, this guidance is still valid and valuable to current learning trends and designs. This suggests that user experience designers for education need to pay attention to the guidance provided by psychology when designing learning management systems, placing content in a course, and choosing which aesthetics to follow.
ContributorsLapujade, Lily Ann (Author) / Branaghan, Russell (Thesis director) / Roscoe, Rod (Committee member) / Human Systems Engineering (Contributor, Contributor) / College of Integrative Sciences and Arts (Contributor) / Barrett, The Honors College (Contributor)
Created2020-05
Description
The bilingual experience is an often-studied multivariate phenomenon with a heterogeneous population that is often described using subtypes of bilingualism. “Bilingualism” as well as its subtypes lack consistent definitions and often share overlapping features, requiring researchers to measure a number of aspects of the bilingual experience. Different variables have been operationalized to quantify the language proficiencies, use, and histories of bilinguals, but the combination of these variables and their contributions to these subtypes often vary between studies on bilingualism. Research supports that these variables have an influence not only on bilingual classification, but also on non-linguistic outcomes including perceptions of self-worth and bicultural identification. To date, there is a lack of research comparing the quantification of these bilingual subtypes and these non-linguistic outcomes, despite research supporting the need to address both. Person-centered approaches such as latent profile analysis (LPA) and fuzzy set qualitative comparative analysis (fsQCA) have been applied to describe other multivariate constructs with heterogeneous populations, but these applications have yet to be used with bilingualism. The present study integrates models of bilingualism with these analytic methods in order to quantitatively identify latent profiles of bilinguals, describe the sets of conditions that define these subtypes, and to characterize the subjective experiences that differentiate these subtypes. The first study uses an existing data set of participants who completed the Language and Social Background Questionnaire (LSBQ) and performs LPA and fsQCA, identifying latent profiles and the sets of conditions that these subtypes. The following studies use a second set of bilinguals who also completed the LSBQ as well as a supplementary questionnaire, characterizing their identification with biculturalism and their feelings of self-worth. The analyses are repeated with these data to describe the profiles within these data and the subjective experiences in common. Finally, all analyses are repeated with the combined datasets to develop a final model of bilingual subtypes, describing the differences in language use and history within each subtype. Results demonstrate that latent models can be used to consistently characterize bilingual subtypes, while also providing additional information about the relationship between individual bilingual history and attitudes towards cultural identification.
ContributorsMcGee, Samuel (Author) / Azuma, Tamiko (Thesis advisor) / Gray, Shelley (Committee member) / Roscoe, Rod (Committee member) / Grimm, Kevin (Committee member) / Arizona State University (Publisher)
Created2022
Description
Although knowledge about effective teaching and learning exists, and theories of change strategies are considered, the lack of the understanding of the behavior of engineering faculty during curricular change remains a major contributor against robust efforts for change. In this work, faculty adaptability is conceptualized as self-regulation during curricular change. Faculty participants were recruited from two divergent curricular change contexts: one that is prescribed with interdependence while the other is emergent with uncertainty. In this study, attitude toward context’s strength is conceptualized along the four dimensions of clarity, consistency, constraints, and consequences of the context, while faculty’s self-efficacy and willingness for adaptability are conceptualized along the three dimensions of planning, reflecting, and adjusting. This study uses a mixed method, quantitative-qualitative, sequential explanatory research design. The quantitative phase addresses the question of “How does faculty group in the first context differ from faculty group in the second context in terms of self-efficacy and willingness for planning, adjusting, and reflecting?” The qualitative phase addresses the question of “How do faculty respond to curricular change, as exhibited in their activities of planning, adjusting, and reflecting during change?” Findings point to differences in patterns of correlations between attitude toward context with both self-efficacy and willingness across the two contexts, even though analysis showed no significant differences between attitude toward context, self-efficacy, and willingness across the two contexts. Moreover, faculty participants’ willingness for adjusting, in both contexts, was not correlated with neither attitude toward context’s clarity nor constraints. Furthermore, in the prescribed context, Group A faculty (self-identified as Lecturers, Senior Lecturers, or Adjunct Faculty) showed higher willingness for planning, adjusting, and reflecting activities, compared to Group B faculty (self-identified as Assistant, Associate or Full Professors). Also, in the prescribed context, Group A faculty showed no overall significant correlation with attitude toward context. This study has implications on the way change is conceived of, designed, and implemented, when special attention is given to faculty as key change agents. Without the comprehensive understanding of the adaptability of faculty as key change agents in the educational system, the effective enacting of curricular change initiatives will remain unfulfilled.
ContributorsAli, Hadi (Author) / McKenna, Ann (Thesis advisor) / Bekki, Jennifer (Committee member) / Roscoe, Rod (Committee member) / Arizona State University (Publisher)
Created2021
Description
This study investigates the energy saving potential of high albedo roof coatings which are designed to reflect a large proportion of solar radiation compared to traditional roofing materials. Using EnergyPlus simulations, the efficacy of silicone, acrylic, and aluminum roof coatings is assessed across two prototype commercial buildings—a standalone retail (2,294 m2 or 24,692 ft2) and a strip-mall (2,090 m2 or 22,500 ft2)—located in four cities: Phoenix, Houston, Los Angeles, and Miami. The performance of reflective coatings was compared with respect to a black roof having a solar reflectance of 5% and a thermal emittance of 90%. A sensitivity analysis was done to assess the impact of solar reflectance and thermal emittance on the ability of roof coatings to reduce surface temperatures, a key factor behind energy savings. This factor plays a crucial role in all three heat transfer mechanisms: conduction, convection, and radiation. The rooftop surface temperature exhibits considerable variation depending on the solar reflectance and thermal emittance attributes of the roof. A contour plot between these properties reveals that high values of both result in reduced cooling needs and a heating penalty which is insignificant when compared with cooling savings for cooling-dominant climates like Phoenix where the cooling demand significantly outweighs the heating demand, yielding significant energy savings. Furthermore, the study also investigates the effects of reflective coatings on buildings that have photovoltaic solar panels installed on them. This includes exploring their impact on building HVAC loads, as well as the performance improvement due to the reduced temperatures beneath them.
ContributorsSharma, Ajay Kumar (Author) / Phelan, Patrick (Thesis advisor) / Neithalath, Narayanan (Committee member) / Milcarek, Ryan (Committee member) / Arizona State University (Publisher)
Created2024
Description
Encouraging women’s pursuit and retention in higher education has been an important movement in the United States over the last several decades. While there has been considerable progress, women are still underrepresented in fields related to Science, Technology, Engineering, and Mathematics (STEM). The most significant gender gap being engineering, where women make up only 21% of all engineering majors. Lack of self-efficacy is one variable that has been implicated as a barrier for women in engineering, due to implicit and explicit biases and discrimination women experience relating to engineering in higher education. Self-compassion has been shown to be strongly correlated with self-efficacy, with explanations theorized at the level of each positive subcomponent: self-kindness, common humanity, and mindfulness. The current study investigates the effects of a self-compassion mindstate induction (SCMI) intervention on engineering self-efficacy compared to a control group. This study also explores gender and race discrimination from faculty and peers in the participants' environment to observe if this plays a role in the effect of the intervention. Women (N = 73) majoring in engineering were recruited from a large southwestern university to participate. A multivariate analysis of covariance (MANCOVA) was conducted, revealing a significant three-way interaction for condition type (SCMI or control), discrimination scores, and engineering self-efficacy from Time 1 to Time 2 (F(1, 69) = 6.51, p = .01). The results of this study suggest that participants in the SCMI condition experienced a significant increase in engineering self-efficacy from Time 1 to Time 2 when controlling for discrimination in the women's environment. Self-compassion based interventions that have the potential to increase engineering self-efficacy may be particularly helpful to women who experience more gender and race discrimination in their environment. Future work should be done to examine discrimination more directly in the context of self-compassion and engineering self-efficacy. These results show promise for using brief, accessible, cost-free, positive psychology interventions to support women pursuing engineering in higher education. This research contributes to the literature aiming to address gender disparities in engineering higher education, laying the groundwork for future interventions that support underrepresented populations in STEM.
ContributorsKampf, Taylor (Author) / Lum, Heather (Thesis advisor) / Roscoe, Rod (Committee member) / Lauer, Claire (Committee member) / Chiou, Erin (Committee member) / Arizona State University (Publisher)
Created2024
Description
Choosing a video streaming service to subscribe to involves a complex decision-making process consisting of multifaceted factors that consumers must carefully consider. This dissertation identifies and examines the factors influencing consumers’ decisions by reviewing research from diverse fields such as human factors, psychology, economics, and human-computer interaction. The identified factors shaping consumers’ choices, in order of importance, are advertisements, social value, price, content, and content discovery methods. Additionally, this study assesses consumers’ willingness to pay for each factor and examines whether their perceived explanation of their choice of platform aligns with the behavior in the choice experiments. Opportunities for future research are discussed including, the potential for developing an algorithm to determine one’s likelihood of subscribing to a streaming platform based on the choice heuristics outlined in this study.
ContributorsWallace, Sydney (Author) / Roscoe, Rod (Thesis advisor) / Cooke, Nancy (Committee member) / Craig, Scotty (Committee member) / Arizona State University (Publisher)
Created2024
Description
Phase change materials (PCMs) are combined sensible-and-latent thermal energy storage materials that can be used to store and dissipate energy in the form of heat. PCMs incorporated into wall-element systems have been well-studied with respect to energy efficiency of building envelopes. New applications of PCMs in infrastructural concrete, e.g., for mitigating early-age cracking and freeze-and-thaw induced damage, have also been proposed. Hence, the focus of this dissertation is to develop a detailed understanding of the physic-chemical and thermo-mechanical characteristics of cementitious systems and novel coating systems for wall-elements containing PCM. The initial phase of this work assesses the influence of interface properties and inter-inclusion interactions between microencapsulated PCM, macroencapsulated PCM, and the cementitious matrix. The fact that these inclusions within the composites are by themselves heterogeneous, and contain multiple components necessitate careful application of models to predict the thermal properties. The next phase observes the influence of PCM inclusions on the fracture and fatigue behavior of PCM-cementitious composites. The compliant nature of the inclusion creates less variability in the fatigue life for these composites subjected to cyclic loading. The incorporation of small amounts of PCM is found to slightly improve the fracture properties compared to PCM free cementitious composites. Inelastic deformations at the crack-tip in the direction of crack opening are influenced by the microscale PCM inclusions. After initial laboratory characterization of the microstructure and evaluation of the thermo-mechanical performance of these systems, field scale applicability and performance were evaluated. Wireless temperature and strain sensors for smart monitoring were embedded within a conventional portland cement concrete pavement (PCCP) and a thermal control smart concrete pavement (TCSCP) containing PCM. The TCSCP exhibited enhanced thermal performance over multiple heating and cooling cycles. PCCP showed significant shrinkage behavior as a result of compressive strains in the reinforcement that were twice that of the TCSCP. For building applications, novel PCM-composites coatings were developed to improve and extend the thermal efficiency. These coatings demonstrated a delay in temperature by up to four hours and were found to be more cost-effective than traditional building insulating materials.
The results of this work prove the feasibility of PCMs as a temperature-regulating technology. Not only do PCMs reduce and control the temperature within cementitious systems without affecting the rate of early property development but they can also be used as an auto-adaptive technology capable of improving the thermal performance of building envelopes.
The results of this work prove the feasibility of PCMs as a temperature-regulating technology. Not only do PCMs reduce and control the temperature within cementitious systems without affecting the rate of early property development but they can also be used as an auto-adaptive technology capable of improving the thermal performance of building envelopes.
ContributorsAguayo, Matthew Joseph (Author) / Neithalath, Narayanan (Thesis advisor) / Rajan, Subramaniam D. (Committee member) / Mobasher, Barzin (Committee member) / Underwood, Benjamin (Committee member) / Liu, Yongming (Committee member) / Arizona State University (Publisher)
Created2018