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Distributed estimation uses many inexpensive sensors to compose an accurate estimate of a given parameter. It is frequently implemented using wireless sensor networks. There have been several studies on optimizing power allocation in wireless sensor networks used for distributed estimation, the vast majority of which assume linear radio-frequency amplifiers. Linear amplifiers are inherently inefficient, so in this dissertation nonlinear amplifiers are examined to gain efficiency while operating distributed sensor networks. This research presents a method to boost efficiency by operating the amplifiers in the nonlinear region of operation. Operating amplifiers nonlinearly presents new challenges. First, nonlinear amplifier characteristics change across manufacturing process variation, temperature, operating voltage, and aging. Secondly, the equations conventionally used for estimators and performance expectations in linear amplify-and-forward systems fail. To compensate for the first challenge, predistortion is utilized not to linearize amplifiers but rather to force them to fit a common nonlinear limiting amplifier model close to the inherent amplifier performance. This minimizes the power impact and the training requirements for predistortion. Second, new estimators are required that account for transmitter nonlinearity. This research derives analytically and confirms via simulation new estimators and performance expectation equations for use in nonlinear distributed estimation. An additional complication when operating nonlinear amplifiers in a wireless environment is the influence of varied and potentially unknown channel gains. The impact of these varied gains and both measurement and channel noise sources on estimation performance are analyzed in this paper. Techniques for minimizing the estimate variance are developed. It is shown that optimizing transmitter power allocation to minimize estimate variance for the most-compressed parameter measurement is equivalent to the problem for linear sensors. Finally, a method for operating distributed estimation in a multipath environment is presented that is capable of developing robust estimates for a wide range of Rician K-factors. This dissertation demonstrates that implementing distributed estimation using nonlinear sensors can boost system efficiency and is compatible with existing techniques from the literature for boosting efficiency at the system level via sensor power allocation. Nonlinear transmitters work best when channel gains are known and channel noise and receiver noise levels are low.
ContributorsSantucci, Robert (Author) / Spanias, Andreas (Thesis advisor) / Tepedelenlioðlu, Cihan (Committee member) / Bakkaloglu, Bertan (Committee member) / Tsakalis, Kostas (Committee member) / Arizona State University (Publisher)
Created2013
Description
ABSTRACT
The purpose of this descriptive study was to gain an understanding of the confidence level held by third, fourth, and fifth grade teachers as to their preparedness for teaching the cognitive demands of the Common Core State Standards (Arizona's College and Career Ready Standards) to all students, in particular Hispanic students living in poverty, who occupy close to a third of all classroom seats in Arizona. The achievement gap between Hispanic students living in poverty and non-Hispanic students of non-poverty status is one of the largest achievement gaps in Arizona, which has existed with minimal change for more than 12 years. By gaining an understanding of the teachers' confidence in teaching critical thinking skills, further support and professional development is suggested to link a teacher's knowledge to instructional practice that in turn increases the academic achievement of Arizona's poor Hispanic students.
The process of gaining this understanding was by using a multi-dimensional survey with 500 third through fifth grade teachers in two uniquely different, but representative, Arizona school districts. Approximately one-third of those teachers responded to the multi-dimensional survey about teaching the critical thinking (CT) skills of Arizona's College and Career Ready Standards for English Language Arts. The survey asked teachers to rate their levels of preparedness for teaching CT to several types of students, to choose a CT definition, describe the relationship of CT and reading, explain how they teach CT to students who are reading below grade level, express the support they need to teach CT to those students, and rate the effectiveness of several CT classroom vignettes for different types of students. Although the questions involved several types of students, the primary focus was on exploring the teachers' position with teaching CT to Low SES Hispanic students.
A disconnect was revealed between the teachers' perception that they had the ability and knowledge necessary to teach critical thinking skills and their ability to identify ineffective critical thinking instructional practices. This disconnect may be interfering with the link between the professional development teachers are currently receiving to implement Common Core State Standards and teachers actively engaging in learning what is needed to effectively teach critical thinking skills to their students.
The purpose of this descriptive study was to gain an understanding of the confidence level held by third, fourth, and fifth grade teachers as to their preparedness for teaching the cognitive demands of the Common Core State Standards (Arizona's College and Career Ready Standards) to all students, in particular Hispanic students living in poverty, who occupy close to a third of all classroom seats in Arizona. The achievement gap between Hispanic students living in poverty and non-Hispanic students of non-poverty status is one of the largest achievement gaps in Arizona, which has existed with minimal change for more than 12 years. By gaining an understanding of the teachers' confidence in teaching critical thinking skills, further support and professional development is suggested to link a teacher's knowledge to instructional practice that in turn increases the academic achievement of Arizona's poor Hispanic students.
The process of gaining this understanding was by using a multi-dimensional survey with 500 third through fifth grade teachers in two uniquely different, but representative, Arizona school districts. Approximately one-third of those teachers responded to the multi-dimensional survey about teaching the critical thinking (CT) skills of Arizona's College and Career Ready Standards for English Language Arts. The survey asked teachers to rate their levels of preparedness for teaching CT to several types of students, to choose a CT definition, describe the relationship of CT and reading, explain how they teach CT to students who are reading below grade level, express the support they need to teach CT to those students, and rate the effectiveness of several CT classroom vignettes for different types of students. Although the questions involved several types of students, the primary focus was on exploring the teachers' position with teaching CT to Low SES Hispanic students.
A disconnect was revealed between the teachers' perception that they had the ability and knowledge necessary to teach critical thinking skills and their ability to identify ineffective critical thinking instructional practices. This disconnect may be interfering with the link between the professional development teachers are currently receiving to implement Common Core State Standards and teachers actively engaging in learning what is needed to effectively teach critical thinking skills to their students.
ContributorsFast, Deborah (Author) / Fischman, Gustavo E (Thesis advisor) / Harris, Connie (Committee member) / Bader, Beth (Committee member) / Arizona State University (Publisher)
Created2014
Description
Sense of Community is related to numerous positive outcomes for university students. The purpose of this study was to explore sense of community amongst low income students who received a last dollar scholarship. This study also sought to understand how students define community and how they interact with communities from their past (before university), present (since they started college), and how they envision their future community involvement after graduation. Through purposive sampling, six low income Arizona State University students were selected based on similar characteristics. The scholarship that they belong to selects them based on financial need, integrity, and prolonged commitment to community service. Using a qualitative narrative inquiry, I interviewed participants about their understanding and experiences with communities. Interviews were audio recorded and transcribed verbatim for analysis. Based on the analysis, I identified three major themes: community as construction, community as nonlinear, and community as intersectional. Drawing from participants' definitions and experiences of community, I argue that community is a construction. In other words, individuals create their own constructions of community, and their actions vary based on that construction. Participants also experience their communities intersectionally, that is individual's experience their communities as coexisting and through multiple community perspectives, rather than as a single stand-alone entity. Finally, community does not exist as part of a linear time paradigm. Instead community is experienced in terms of relevance to the individual in creating meaning from that community. In addition to the above themes, I also examined participant perspectives of ASU as a community. Based on this research, I recommend that a platform be provided for students to engage in a dialogue about their understanding of community and interactions with communities. Moreover, I suggest researchers utilize intersectionality, constructionism, and non-linear time to frame future research on sense of community. This research is significant because it helps us understand student engagement, and offers a framework through which universities can provide students an opportunity to better understand their own sense of community.
ContributorsWhite, Misha Alexsandra (Author) / Foroughi-Mobarakeh, Behrang (Thesis director) / Legg, Walter Eric (Committee member) / School of Community Resources and Development (Contributor) / School of Social Transformation (Contributor) / Barrett, The Honors College (Contributor)
Created2017-05
Description
This action research study (a) explored how institutionally labeled “at-risk” Latina/o students described their experiences in an opportunity to learn environment within an academic intervention program, (b) examined how these students experienced caring relationships with their teachers in an opportunity to learn environment when compared to their other core academic classes, and (c) investigated how school leaders created conditions to further support these students’ academic success on a larger scale. This action research study utilized a sequential phenomenological qualitative approach. Critical Race Theory, Critical Pedagogy, and Care theory served as the theoretical frameworks for this study. The blending of these theories worked to push Latina/o students’ narrative reflections to emerge as constitutive and instructive voices speaking back against the inequalities in the educational setting, and offered counterstories about the caring dynamics of Latina/o students in the classroom. Participants included high school students identified as “at-risk” and in an academic intervention class
ContributorsVillena, Breanna (Author) / Liou, Daniel (Thesis advisor) / Tefera, Adai (Committee member) / Vasquez-Robles, Veronica (Committee member) / Arizona State University (Publisher)
Created2016
Description
In recent years, the development of Control Barrier Functions (CBF) has allowed safety guarantees to be placed on nonlinear control affine systems. While powerful as a mathematical tool, CBF implementations on systems with high relative degree constraints can become too computationally intensive for real-time control. Such deployments typically rely on the analysis of a system's symbolic equations of motion, leading to large, platform-specific control programs that do not generalize well. To address this, a more generalized framework is needed. This thesis provides a formulation for second-order CBFs for rigid open kinematic chains. An algorithm for numerically computing the safe control input of a CBF is then introduced based on this formulation. It is shown that this algorithm can be used on a broad category of systems, with specific examples shown for convoy platooning, drone obstacle avoidance, and robotic arms with large degrees of freedom. These examples show up to three-times performance improvements in computation time as well as 2-3 orders of magnitude in the reduction in program size.
ContributorsPietz, Daniel Johannes (Author) / Fainekos, Georgios (Thesis advisor) / Vrudhula, Sarma (Thesis advisor) / Pedrielli, Giulia (Committee member) / Pavlic, Theodore (Committee member) / Arizona State University (Publisher)
Created2022
Description
The dissertation addresses questions tied in to the challenges posed by the impact of environmental factors on the nonlinear dynamics of social upward mobility. The proportion of educated individuals from various socio-economic backgrounds is used as a proxy for the environmental impact on the status quo state.
Chapter 1 carries out a review of the mobility models found in the literature and sets the economic context of this dissertation. Chapter 2 explores a simple model that considers poor and rich classes and the impact that educational success may have on altering mobility patterns. The role of the environment is modeled through the use of a modified version of the invasion/extinction model of Richard Levins. Chapter 3 expands the socio-economic classes to include a large middle class to study the role of social mobility in the presence of higher heterogeneity. Chapter 4 includes demographic growth and explores what would be the time scales needed to accelerate mobility. The dissertation asked how long it will take to increase by 22% the proportion of educated from the poor classes under demographic versus non-demographic growth conditions. Chapter 5 summarizes results and includes a discussion of results. It also explores ways of modeling the influence of nonlinear dynamics of mobility, via exogenous factors. Finally, Chapter 6 presents economic perspectives about the role of environmental influence on college success. The framework can be used to incorporate the impact of economic factors and social changes, such as unemployment, or gap between the haves and have nots. The dissertation shows that peer influence (poor influencing the poor) has a larger effect than class influence (rich influencing the poor). Additionally, more heterogeneity may ease mobility of groups but results depend on initial conditions. Finally, average well-being of the community and income disparities may improve over time. Finally, population growth may extend time scales needed to achieve a specific goal of educated poor.
Chapter 1 carries out a review of the mobility models found in the literature and sets the economic context of this dissertation. Chapter 2 explores a simple model that considers poor and rich classes and the impact that educational success may have on altering mobility patterns. The role of the environment is modeled through the use of a modified version of the invasion/extinction model of Richard Levins. Chapter 3 expands the socio-economic classes to include a large middle class to study the role of social mobility in the presence of higher heterogeneity. Chapter 4 includes demographic growth and explores what would be the time scales needed to accelerate mobility. The dissertation asked how long it will take to increase by 22% the proportion of educated from the poor classes under demographic versus non-demographic growth conditions. Chapter 5 summarizes results and includes a discussion of results. It also explores ways of modeling the influence of nonlinear dynamics of mobility, via exogenous factors. Finally, Chapter 6 presents economic perspectives about the role of environmental influence on college success. The framework can be used to incorporate the impact of economic factors and social changes, such as unemployment, or gap between the haves and have nots. The dissertation shows that peer influence (poor influencing the poor) has a larger effect than class influence (rich influencing the poor). Additionally, more heterogeneity may ease mobility of groups but results depend on initial conditions. Finally, average well-being of the community and income disparities may improve over time. Finally, population growth may extend time scales needed to achieve a specific goal of educated poor.
ContributorsMontalvo, Cesar Paul (Author) / Castillo-Chavez, Carlos (Thesis advisor) / Mubayi, Anuj (Thesis advisor) / Perrings, Charles (Committee member) / Kang, Yun (Committee member) / Arizona State University (Publisher)
Created2020