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- Creators: Arizona State University
- Member of: ASU Electronic Theses and Dissertations
Description
Laboratory assessment of crack resistance and propagation in asphalt concrete is a difficult task that challenges researchers and engineers. Several fracture mechanics based laboratory tests currently exist; however, these tests and subsequent analysis methods rely on elastic behavior assumptions and do not consider the time-dependent nature of asphalt concrete. The C* Line Integral test has shown promise to capture crack resistance and propagation within asphalt concrete. In addition, the fracture mechanics based C* parameter considers the time-dependent creep behavior of the materials. However, previous research was limited and lacked standardized test procedure and detailed data analysis methods were not fully presented. This dissertation describes the development and refinement of the C* Fracture Test (CFT) based on concepts of the C* line integral test. The CFT is a promising test to assess crack propagation and fracture resistance especially in modified mixtures. A detailed CFT test protocol was developed based on a laboratory study of different specimen sizes and test conditions. CFT numerical simulations agreed with laboratory results and indicated that the maximum horizontal tensile stress (Mode I) occurs at the crack tip but diminishes at longer crack lengths when shear stress (Mode II) becomes present. Using CFT test results and the principles of time-temperature superposition, a crack growth rate master curve was successfully developed to describe crack growth over a range of test temperatures. This master curve can be applied to pavement design and analysis to describe crack propagation as a function of traffic conditions and pavement temperatures. Several plant mixtures were subjected to the CFT and results showed differences in resistance to crack propagation, especially when comparing an asphalt rubber mixture to a conventional one. Results indicated that crack propagation is ideally captured within a given range of dynamic modulus values. Crack growth rates and C* prediction models were successfully developed for all unmodified mixtures in the CFT database. These models can be used to predict creep crack propagation and the C* parameter when laboratory testing is not feasible. Finally, a conceptual approach to incorporate crack growth rate and the C* parameter into pavement design and analysis was presented.
ContributorsStempihar, Jeffrey (Author) / Kaloush, Kamil (Thesis advisor) / Witczak, Matthew (Committee member) / Mamlouk, Michael (Committee member) / Arizona State University (Publisher)
Created2013
Description
The signing of the No Child Left Behind Act in 2001 created a need for Title 1 principals to conceptualize and operationalize parent engagement. This study examines how three urban principals in Arizona implemented the mandates of the Act as it pertains to parent involvement. The purpose of this qualitative case study is to examine how principals operationalize and conceptualize parent involvement as they navigate barriers and laws particular to the state of Arizona. This study sought to understand issues surrounding parent involvement in Title 1 schools in Arizona. The beliefs and interview dialogue of the principals as it pertains to parent engagement provided an understanding of how urban principals in Arizona implement the aspects of No Child Left Behind Act that deal with parent involvement. The research study concluded that parents have community cultural wealth that contributes to the success of the students of engaged parents and that cultural responsive leadership assists principals with engaging parents in their schools. The research concludes that a gap exists between how parents and principals perceive and construct parent engagement versus what is prescribed in No Child Left Behind Act.
ContributorsConley, Loraine (Author) / Brayboy, Bryan (Thesis advisor) / Mccarty, Teresa (Committee member) / Scott, Kimberly (Committee member) / Arizona State University (Publisher)
Created2012
Description
With changes in federal legislation and the proposed reauthorization of The Elementary and Secondary Education Act, school administrators are held to high standards in an attempt to improve achievement for all students. They no longer just manage their schools but must now be instructional leaders charged with observing and conferencing with teachers, leading professional development aligned to data, and measuring results. Classroom walkthroughs have become a way of assisting with these tasks while supporting the mission of each school. The purpose of this research was to describe how walkthroughs operate in practice and how they were experienced by school administration, teacher leaders, and teachers at two schools within the same suburban district. Interviews illustrated that experiences were varied using the classroom walkthrough protocol. Continued professional development needed to occur with administrators and teachers. Participants shared their thoughts on implementation and usage, as well as made recommendations to schools and/or districts considering implementing classroom walkthroughs. Results also indicated a great deal of attention paid to the collection of data within the schools but there was less consensus on the analysis and use of the collected data. There was also confusion with teachers as to the vision, purpose, and goals of using classroom walkthroughs. Changes in leadership during the five years since implementation and young administrators, who were relatively new in their positions, helped shape school experiences. Recommendations to schools and/or districts considering implementation focused on support from the district office, a need for help with data collection and analysis, and a clear vision for the use of the protocol. Interviewees mentioned it would benefit districts and schools to develop a shared vocabulary for instructional engagement, alignment, and rigor, as well as a focus for professional development. They also shared the view that calibration conferences and conversations, centered on instruction, provided a focus for teaching and learning within a school and/or district.
ContributorsCunningham, Alexa Renee (Author) / Danzig, Arnold (Thesis advisor) / Harris, Connie (Committee member) / Hurley, Beverly (Committee member) / Arizona State University (Publisher)
Created2012
Description
Woven fabric composite materials are widely used in the construction of aircraft engine fan containment systems, mostly due to their high strength to weight ratios and ease of implementation. The development of a predictive model for fan blade containment would provide great benefit to engine manufactures in shortened development cycle time, less risk in certification and fewer dollars lost to redesign/recertification cycles. A mechanistic user-defined material model subroutine has been developed at Arizona State University (ASU) that captures the behavioral response of these fabrics, namely Kevlar® 49, under ballistic loading. Previously developed finite element models used to validate the consistency of this material model neglected the effects of the physical constraints imposed on the test setup during ballistic testing performed at NASA Glenn Research Center (NASA GRC). Part of this research was to explore the effects of these boundary conditions on the results of the numerical simulations. These effects were found to be negligible in most instances. Other material models for woven fabrics are available in the LS-DYNA finite element code. One of these models, MAT234: MAT_VISCOELASTIC_LOOSE_FABRIC (Ivanov & Tabiei, 2004) was studied and implemented in the finite element simulations of ballistic testing associated with the FAA ASU research. The results from these models are compared to results obtained from the ASU UMAT as part of this research. The results indicate an underestimation in the energy absorption characteristics of the Kevlar 49 fabric containment systems. More investigation needs to be performed in the implementation of MAT234 for Kevlar 49 fabric. Static penetrator testing of Kevlar® 49 fabric was performed at ASU in conjunction with this research. These experiments are designed to mimic the type of loading experienced during fan blade out events. The resulting experimental strains were measured using a non-contact optical strain measurement system (ARAMIS).
ContributorsFein, Jonathan (Author) / Rajan, Subramaniam D. (Thesis advisor) / Mobasher, Barzin (Committee member) / Jiang, Hanqing (Committee member) / Arizona State University (Publisher)
Created2012
Description
The purpose of the research study was to explore the perceptions of Navajo mothers and Navajo fathers in the development and childrearing practices of their children and to what extent each parent was involved in their children by gender and age. The objective of the interviews was to capture the perceptions of each parent as to child development and childrearing practices as well as the beliefs that they have on parental involvement. In the current study, the interviews provided information regarding attitudes and perceptions of parental involvement from the Navajo mothers and the Navajo fathers who participated in the study. By using probing questions, deeper insights into the understanding and perceptions of parental involvement were obtained.
ContributorsTsosie, Berdina (Author) / Appleton, Nicholas A (Thesis advisor) / Spencer, Dee A (Committee member) / Duplissis, Mark (Committee member) / Arizona State University (Publisher)
Created2012
Description
Ultimately, the examples and foundation provided at home will impact the child as a student and lifelong learner. In Navajo society, there are some families who continue to instill the importance of heritage language and culture. And then there are those who choose not to, or who are not capable of doing so due to the lack of knowledge to share such teachings. Diné language and culture are vital elements of who we are as Diné. They are what identify us as a people. Our language and culture separate us from the western society. As parents and educators, our attitudes affect our homes, schools, and children. Our way of thinking may inhibit or perpetuate cultural teachings. However, no one knows how parents' attitudes affect cultural integration at an immersion school. This quantitative study examined parents' attitudes toward cultural integration in a Navajo language immersion school (Ts4hootsoo7 Diné Bi')lta' with the Window Rock Unified School District #8 in Fort Defiance, Arizona). Surveys were used to examine parents' attitudes about language and cultural integration. The survey asked about Navajo language and culture, about the extent to which it was practiced at home, and their opinions about how Navajo language and culture was being taught at school. The data were reported in basic descriptive statistics for the total group of respondents and then disaggregated by age, place of birth (on the reservation or off), gender, marital status, and highest grade completed in school. The data has shown that overall parents are supportive of Navajo language and culture. Their attitudes may vary based on age, place of birth, gender, marital status, and education. In spite of this, Navajo language and culture are in the home. However, the degree to which it is spoken or practiced is not measured. Parents are supportive of the school teaching Navajo language and culture.
ContributorsPlatero, Audra J (Author) / Spencer, Dee Ann (Thesis advisor) / Appleton, Nicholas A. (Committee member) / Gilmore, Treva (Committee member) / Arizona State University (Publisher)
Created2012
Description
Urban water systems face sustainability challenges ranging from water quality, leaks, over-use, energy consumption, and long-term supply concerns. Resiliency challenges include the capacity to respond to drought, managing pipe deterioration, responding to natural disasters, and preventing terrorism. One strategy to enhance sustainability and resiliency is the development and adoption of smart water grids. A smart water grid incorporates networked monitoring and control devices into its structure, which provides diverse, real-time information about the system, as well as enhanced control. Data provide input for modeling and analysis, which informs control decisions, allowing for improvement in sustainability and resiliency. While smart water grids hold much potential, there are also potential tradeoffs and adoption challenges. More publicly available cost-benefit analyses are needed, as well as system-level research and application, rather than the current focus on individual technologies. This thesis seeks to fill one of these gaps by analyzing the cost and environmental benefits of smart irrigation controllers. Smart irrigation controllers can save water by adapting watering schedules to climate and soil conditions. The potential benefit of smart irrigation controllers is particularly high in southwestern U.S. states, where the arid climate makes water scarcer and increases watering needs of landscapes. To inform the technology development process, a design for environment (DfE) method was developed, which overlays economic and environmental performance parameters under different operating conditions. This method is applied to characterize design goals for controller price and water savings that smart irrigation controllers must meet to yield life cycle carbon dioxide reductions and economic savings in southwestern U.S. states, accounting for regional variability in electricity and water prices and carbon overhead. Results from applying the model to smart irrigation controllers in the Southwest suggest that some areas are significantly easier to design for.
ContributorsMutchek, Michele (Author) / Allenby, Braden (Thesis advisor) / Williams, Eric (Committee member) / Westerhoff, Paul (Committee member) / Arizona State University (Publisher)
Created2012
Description
This study focuses on implementing probabilistic nature of material properties (Kevlar® 49) to the existing deterministic finite element analysis (FEA) of fabric based engine containment system through Monte Carlo simulations (MCS) and implementation of probabilistic analysis in engineering designs through Reliability Based Design Optimization (RBDO). First, the emphasis is on experimental data analysis focusing on probabilistic distribution models which characterize the randomness associated with the experimental data. The material properties of Kevlar® 49 are modeled using experimental data analysis and implemented along with an existing spiral modeling scheme (SMS) and user defined constitutive model (UMAT) for fabric based engine containment simulations in LS-DYNA. MCS of the model are performed to observe the failure pattern and exit velocities of the models. Then the solutions are compared with NASA experimental tests and deterministic results. MCS with probabilistic material data give a good prospective on results rather than a single deterministic simulation results. The next part of research is to implement the probabilistic material properties in engineering designs. The main aim of structural design is to obtain optimal solutions. In any case, in a deterministic optimization problem even though the structures are cost effective, it becomes highly unreliable if the uncertainty that may be associated with the system (material properties, loading etc.) is not represented or considered in the solution process. Reliable and optimal solution can be obtained by performing reliability optimization along with the deterministic optimization, which is RBDO. In RBDO problem formulation, in addition to structural performance constraints, reliability constraints are also considered. This part of research starts with introduction to reliability analysis such as first order reliability analysis, second order reliability analysis followed by simulation technique that are performed to obtain probability of failure and reliability of structures. Next, decoupled RBDO procedure is proposed with a new reliability analysis formulation with sensitivity analysis, which is performed to remove the highly reliable constraints in the RBDO, thereby reducing the computational time and function evaluations. Followed by implementation of the reliability analysis concepts and RBDO in finite element 2D truss problems and a planar beam problem are presented and discussed.
ContributorsDeivanayagam, Arumugam (Author) / Rajan, Subramaniam D. (Thesis advisor) / Mobasher, Barzin (Committee member) / Neithalath, Narayanan (Committee member) / Arizona State University (Publisher)
Created2012
Description
In this study, the Arizona State University Mathematics and Science Teaching Fellows 2010 program was analyzed qualitatively from start to finish to determine the impact of the research experience on teachers in the classroom. The sample for the study was the 2010 cohort of eight high school science teachers. Erickson's (1986) interpretive, participant observational fieldwork method was used to report data by means of detailed descriptions of the research experience and classroom implementation. Data was collected from teacher documents, interviews, and observations. The findings revealed various factors that were responsible for an ineffective implementation of the research experience in the classroom such as research experience, curriculum support, availability of resources, and school curriculum. Implications and recommendations for future programs are discussed in the study.
ContributorsSen, Tapati (Author) / Baker, Dale (Thesis advisor) / Culbertson, Robert (Committee member) / Margolis, Eric (Committee member) / Arizona State University (Publisher)
Created2012
Description
Immigration status and educational opportunities are at the forefront of the current national conversation regarding "DREAMers": children of immigrants brought to the United States at a young age who lack legal status but are raised and educated in the American system. In 2006, Arizona voters passed Proposition 300, in part prohibiting in-state tuition for state colleges and universities to individuals who cannot provide proof of citizenship or legal residency. For those DREAMers who hoped to attend college following high school, this policy affected their ability to enroll because of the increased tuition and lack of eligibility for state-sponsored financial aid. This law's impact is also present in Arizona's public high schools. High schools, in partnership with community colleges, have created a robust system of dual or concurrent enrollment courses: college classes offered to high school students as a means of accelerating their learning. In this arrangement, full payments for tuition are required by families or by the programs that support the students, creating a system in public schools where some students are able to participate while others cannot due to their residency status. The aim of this study was to determine the educational, social, and emotional effects of Proposition 300 upon undocumented secondary students. Through qualitative analysis, this study relies upon focus group interviews with high school graduates impacted by Proposition 300 before graduation. Interviews were also conducted with parents and with educators representing both secondary and higher education. A total of nine students, two parents, and four education professionals participated in semi-structured conversations over the course of several months in the fall of 2012. The data was collected, analyzed, and coded, extrapolating common themes related to the review of literature and information from the participants. The findings describe the effects Proposition 300 has had as it pertains to undocumented students, their experience of their unequal access to dual or concurrent enrollment, the disconnect they have felt from their "documented" peers, and the emotional impact they have felt as a result of this law. Among the findings, the potential impact of Deferred Action for Childhood Arrivals (DACA), enacted in August 2012, is explored.
ContributorsLaurin, Joel (Author) / Barnett, Joshua (Thesis advisor) / Heck, Thomas (Thesis advisor) / Langley, Janet (Committee member) / Arizona State University (Publisher)
Created2013