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- Creators: Arizona State University
Description
Autonomous vehicle control systems utilize real-time kinematic Global Navigation Satellite Systems (GNSS) receivers to provide a position within two-centimeter of truth. GNSS receivers utilize the satellite signal time of arrival estimates to solve for position; and multipath corrupts the time of arrival estimates with a time-varying bias. Time of arrival estimates are based upon accurate direct sequence spread spectrum (DSSS) code and carrier phase tracking. Current multipath mitigating GNSS solutions include fixed radiation pattern antennas and windowed delay-lock loop code phase discriminators. A new multipath mitigating code tracking algorithm is introduced that utilizes a non-symmetric correlation kernel to reject multipath. Independent parameters provide a means to trade-off code tracking discriminant gain against multipath mitigation performance. The algorithm performance is characterized in terms of multipath phase error bias, phase error estimation variance, tracking range, tracking ambiguity and implementation complexity. The algorithm is suitable for modernized GNSS signals including Binary Phase Shift Keyed (BPSK) and a variety of Binary Offset Keyed (BOC) signals. The algorithm compensates for unbalanced code sequences to ensure a code tracking bias does not result from the use of asymmetric correlation kernels. The algorithm does not require explicit knowledge of the propagation channel model. Design recommendations for selecting the algorithm parameters to mitigate precorrelation filter distortion are also provided.
ContributorsMiller, Steven (Author) / Spanias, Andreas (Thesis advisor) / Tepedelenlioğlu, Cihan (Committee member) / Tsakalis, Konstantinos (Committee member) / Zhang, Junshan (Committee member) / Arizona State University (Publisher)
Created2013
Description
This study sought to analyze the messages being conveyed through the discourse utilized in presenting the public face of The Arizona Early Childhood Development and Health Board, popularly known as First Things First (FTF) and to reveal how the different discourses and ideologies within FTF have been in the past and currently are "contending and struggling for dominance (Wodak, 2007)." FTF is located within the policy realm of Early Childhood Education and Care (ECEC). The people and the system have been very influential in guiding the course and policies set forth in Arizona since the citizen initiative, Proposition 203, passed in 2006, which allowed for the creation of the Early Childhood Development and Health Board. Lakoff's techniques for analyzing frames of discourse were utilized in conjunction with critical discourse analysis in order to tease out frames of reference, shifts in both discourse and frames, specific modes of messaging, and consistencies and inconsistencies within the public face presented by FTF.
ContributorsMiller, Lisa (Author) / Swadener, Elizabeth B (Thesis advisor) / Nakagawa, Kathy (Committee member) / Romero, Mary (Committee member) / Arizona State University (Publisher)
Created2013
Description
As digital media practices become readily available in today's classrooms, literacy and literacy instruction are changing in profound ways (Alvermann, 2010). Professional organizations emphasize the importance of integrating new literacies (New London Group, 1996) practices into language-arts instruction (IRA, 2009; NCTE, 2005). As a result, teachers search for effective ways to incorporate the new literacies in an effort to engage students. Therefore, this study was designed to investigate the potential of digital storytelling as participatory media for writing instruction. This case study was conducted during the fall semester of 2012 in one first-grade classroom and one second-grade classroom in the Southwestern United States. The study addressed ten interrelated research questions relating to how primary-grade students performed in relation to the Common Core writing standards, how they were motivated, how they formed a meta- language to talk about their writing, how they developed identities as writers, and how they were influenced by their teachers' philosophies and instructional approaches. Twenty-two first-grade students and 24 second-grade students used the MovieMaker software to create digital stories of personal narratives. Data included field notes, interviews with teachers and students, teacher journals, my own journal, artifacts of teachers' lesson plans, photographs, students' writing samples, and their digital stories. Qualitative data were analyzed by thematic analysis (Patton, 1990) and discourse analysis (Gee, 2011). Writing samples were scored by rubrics based on the Common Core State Standards. The study demonstrated how digital storytelling can be used to; (a) guide teachers in implementing new literacies in primary grades; (b) illustrate digital storytelling as writing; (c) develop students' meta-language to talk about writing; (d) impact students' perceptions as writers; (e) meet Common Core State Standards for writing; (f) improve students' skills as writers; (g) build students' identities as writers; (h) impact academic writing; (i) engage students in the writing process; and (j) illustrate the differences in writing competencies between first- and second-grade students. The study provides suggestions for teachers interested in incorporating digital storytelling in primary-grade classrooms.
ContributorsFoley, Leslie M (Author) / Guzzetti, Barbara J. (Thesis advisor) / Hayes, Elisabeth R. (Committee member) / Gee, James P (Committee member) / Arizona State University (Publisher)
Created2013
Description
The purpose of this study was to investigate critical literacy practices in two prehistoric exhibits in a natural history museum. Bourdieu's habitus and Bakhtin's dialogism served as theoretical frames to collect and analyze data. Data were collected and triangulated using field notes, interview transcriptions, archives, and other data sources to critically scrutinize textual meaning and participant responses. Spradley's (1979) domain analysis was used to sort and categorize data in the early stage. Glaser and Strauss's (1967) constant comparative method was used to code data. My major findings were that museum texts within this context represent embedded beliefs and values that were interwoven with curators` habitus, tastes and capital, as well as institutional policies. The texts in the two Hohokam exhibits endorse a certain viewpoint of learning. Teachers and the public were not aware of the communicative role that the museum played in the society. In addition, museum literacy/ies were still practiced in a fundamental way as current practices in the classroom, which may not support the development of critical literacy. In conclusion, the very goal for critical museum literacy is to help students and teachers develop intellectual strategies to read the word and the world in informal learning environments.
ContributorsLiang, Sheau-yann (Author) / Mccarty, Teresa (Thesis advisor) / Marsh, Josephine (Committee member) / Blumenfeld-Jones, Donald (Committee member) / Welsh, Peter (Committee member) / Arizona State University (Publisher)
Created2013
Description
"Sensor Decade" has been labeled on the first decade of the 21st century. Similar to the revolution of micro-computer in 1980s, sensor R&D; developed rapidly during the past 20 years. Hard workings were mainly made to minimize the size of devices with optimal the performance. Efforts to develop the small size devices are mainly concentrated around Micro-electro-mechanical-system (MEMS) technology. MEMS accelerometers are widely published and used in consumer electronics, such as smart phones, gaming consoles, anti-shake camera and vibration detectors. This study represents liquid-state low frequency micro-accelerometer based on molecular electronic transducer (MET), in which inertial mass is not the only but also the conversion of mechanical movement to electric current signal is the main utilization of the ionic liquid. With silicon-based planar micro-fabrication, the device uses a sub-micron liter electrolyte droplet sealed in oil as the sensing body and a MET electrode arrangement which is the anode-cathode-cathode-anode (ACCA) in parallel as the read-out sensing part. In order to sensing the movement of ionic liquid, an imposed electric potential was applied between the anode and the cathode. The electrode reaction, I_3^-+2e^___3I^-, occurs around the cathode which is reverse at the anodes. Obviously, the current magnitude varies with the concentration of ionic liquid, which will be effected by the movement of liquid droplet as the inertial mass. With such structure, the promising performance of the MET device design is to achieve 10.8 V/G (G=9.81 m/s^2) sensitivity at 20 Hz with the bandwidth from 1 Hz to 50 Hz, and a low noise floor of 100 ug/sqrt(Hz) at 20 Hz.
ContributorsLiang, Mengbing (Author) / Yu, Hongyu (Thesis advisor) / Jiang, Hanqing (Committee member) / Kozicki, Micheal (Committee member) / Arizona State University (Publisher)
Created2013
Description
With increasing transistor volume and reducing feature size, it has become a major design constraint to reduce power consumption also. This has given rise to aggressive architectural changes for on-chip power management and rapid development to energy efficient hardware accelerators. Accordingly, the objective of this research work is to facilitate software developers to leverage these hardware techniques and improve energy efficiency of the system. To achieve this, I propose two solutions for Linux kernel: Optimal use of these architectural enhancements to achieve greater energy efficiency requires accurate modeling of processor power consumption. Though there are many models available in literature to model processor power consumption, there is a lack of such models to capture power consumption at the task-level. Task-level energy models are a requirement for an operating system (OS) to perform real-time power management as OS time multiplexes tasks to enable sharing of hardware resources. I propose a detailed design methodology for constructing an architecture agnostic task-level power model and incorporating it into a modern operating system to build an online task-level power profiler. The profiler is implemented inside the latest Linux kernel and validated for Intel Sandy Bridge processor. It has a negligible overhead of less than 1\% hardware resource consumption. The profiler power prediction was demonstrated for various application benchmarks from SPEC to PARSEC with less than 4\% error. I also demonstrate the importance of the proposed profiler for emerging architectural techniques through use case scenarios, which include heterogeneous computing and fine grained per-core DVFS. Along with architectural enhancement in general purpose processors to improve energy efficiency, hardware accelerators like Coarse Grain reconfigurable architecture (CGRA) are gaining popularity. Unlike vector processors, which rely on data parallelism, CGRA can provide greater flexibility and compiler level control making it more suitable for present SoC environment. To provide streamline development environment for CGRA, I propose a flexible framework in Linux to do design space exploration for CGRA. With accurate and flexible hardware models, fine grained integration with accurate architectural simulator, and Linux memory management and DMA support, a user can carry out limitless experiments on CGRA in full system environment.
ContributorsDesai, Digant Pareshkumar (Author) / Vrudhula, Sarma (Thesis advisor) / Chakrabarti, Chaitali (Committee member) / Wu, Carole-Jean (Committee member) / Arizona State University (Publisher)
Created2013
Description
Researchers have postulated that math academic achievement increases student success in college (Lee, 2012; Silverman & Seidman, 2011; Vigdor, 2013), yet 80% of universities and 98% of community colleges require many of their first-year students to be placed in remedial courses (Bettinger & Long, 2009). Many high school graduates are entering college ill prepared for the rigors of higher education, lacking understanding of basic and important principles (ACT, 2012). The desire to increase academic achievement is a wide held aspiration in education and the idea of adapting instruction to individuals is one approach to accomplish this goal (Lalley & Gentile, 2009a). Frequently, adaptive learning environments rely on a mastery learning approach, it is thought that when students are afforded the opportunity to master the material, deeper and more meaningful learning is likely to occur. Researchers generally agree that the learning environment, the teaching approach, and the students' attributes are all important to understanding the conditions that promote academic achievement (Bandura, 1977; Bloom, 1968; Guskey, 2010; Cassen, Feinstein & Graham, 2008; Changeiywo, Wambugu & Wachanga, 2011; Lee, 2012; Schunk, 1991; Van Dinther, Dochy & Segers, 2011). The present study investigated the role of college students' affective attributes and skills, such as academic competence and academic resilience, in an adaptive mastery-based learning environment on their academic performance, while enrolled in a remedial mathematics course. The results showed that the combined influence of students' affective attributes and academic resilience had a statistically significant effect on students' academic performance. Further, the mastery-based learning environment also had a significant effect on their academic competence and academic performance.
ContributorsFoshee, Cecile Mary (Author) / Atkinson, Robert K (Thesis advisor) / Elliott, Stephen N. (Committee member) / Horan, John (Committee member) / Arizona State University (Publisher)
Created2013
Description
This research examines the current challenges of using Lamb wave interrogation methods to localize fatigue crack damage in a complex metallic structural component subjected to unknown temperatures. The goal of this work is to improve damage localization results for a structural component interrogated at an unknown temperature, by developing a probabilistic and reference-free framework for estimating Lamb wave velocities and the damage location. The methodology for damage localization at unknown temperatures includes the following key elements: i) a model that can describe the change in Lamb wave velocities with temperature; ii) the extension of an advanced time-frequency based signal processing technique for enhanced time-of-flight feature extraction from a dispersive signal; iii) the development of a Bayesian damage localization framework incorporating data association and sensor fusion. The technique requires no additional transducers to be installed on a structure, and allows for the estimation of both the temperature and the wave velocity in the component. Additionally, the framework of the algorithm allows it to function completely in an unsupervised manner by probabilistically accounting for all measurement origin uncertainty. The novel algorithm was experimentally validated using an aluminum lug joint with a growing fatigue crack. The lug joint was interrogated using piezoelectric transducers at multiple fatigue crack lengths, and at temperatures between 20°C and 80°C. The results showed that the algorithm could accurately predict the temperature and wave speed of the lug joint. The localization results for the fatigue damage were found to correlate well with the true locations at long crack lengths, but loss of accuracy was observed in localizing small cracks due to time-of-flight measurement errors. To validate the algorithm across a wider range of temperatures the electromechanically coupled LISA/SIM model was used to simulate the effects of temperatures. The numerical results showed that this approach would be capable of experimentally estimating the temperature and velocity in the lug joint for temperatures from -60°C to 150°C. The velocity estimation algorithm was found to significantly increase the accuracy of localization at temperatures above 120°C when error due to incorrect velocity selection begins to outweigh the error due to time-of-flight measurements.
ContributorsHensberry, Kevin (Author) / Chattopadhyay, Aditi (Thesis advisor) / Liu, Yongming (Committee member) / Papandreou-Suppappola, Antonia (Committee member) / Arizona State University (Publisher)
Created2013
Description
The object of this study was a 26 year old residential Photovoltaic (PV) monocrystalline silicon (c-Si) power plant, called Solar One, built by developer John F. Long in Phoenix, Arizona (a hot-dry field condition). The task for Arizona State University Photovoltaic Reliability Laboratory (ASU-PRL) graduate students was to evaluate the power plant through visual inspection, electrical performance, and infrared thermography. The purpose of this evaluation was to measure and understand the extent of degradation to the system along with the identification of the failure modes in this hot-dry climatic condition. This 4000 module bipolar system was originally installed with a 200 kW DC output of PV array (17 degree fixed tilt) and an AC output of 175 kVA. The system was shown to degrade approximately at a rate of 2.3% per year with no apparent potential induced degradation (PID) effect. The power plant is made of two arrays, the north array and the south array. Due to a limited time frame to execute this large project, this work was performed by two masters students (Jonathan Belmont and Kolapo Olakonu) and the test results are presented in two masters theses. This thesis presents the results obtained on the north array and the other thesis presents the results obtained on the south array. The resulting study showed that PV module design, array configuration, vandalism, installation methods and Arizona environmental conditions have had an effect on this system's longevity and reliability. Ultimately, encapsulation browning, higher series resistance (potentially due to solder bond fatigue) and non-cell interconnect ribbon breakages outside the modules were determined to be the primary causes for the power loss.
ContributorsBelmont, Jonathan (Author) / Tamizhmani, Govindasamy (Thesis advisor) / Henderson, Mark (Committee member) / Rogers, Bradley (Committee member) / Arizona State University (Publisher)
Created2013
Description
The purpose of professional development is to enhance educator practices so that students may achieve at high levels. Too often, professional development tends to be too broad, general, or unrelated to problems of practice that teachers face in their own classrooms. This action research project builds upon the scholarly research that recognizes the need for professional development to be sustained, connected to teachers' own contexts, focused on specific subject matter, collaborative, and reflective. The goal of this action research study was to facilitate a culture of continuous improvement in teaching and learning by utilizing a model of professional development that challenges teachers to question their practices, utilize research to support their instruction, design an inquiry project that supports a change in practice, and examine changes in student growth. Results suggest that although teachers recognize the complexities that surround professional development, they found that this professional development model focused on their needs as professionals, was sustained over time, and was supported by a variety of professional influences. As a result of the model implemented, teachers reported shifts in their instructional practices and student growth related to personal inquiry projects.
ContributorsHudak, Michele (Author) / Roe, Mary (Thesis advisor) / Weber, Catherine (Committee member) / Chalex, Nancy (Committee member) / Arizona State University (Publisher)
Created2013