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- Genre: Masters Thesis
- Creators: Arizona State University
- Creators: Chakraborty, Bijeta
- Member of: ASU Electronic Theses and Dissertations
Description
Efficiency of components is an ever increasing area of importance to portable applications, where a finite battery means finite operating time. Higher efficiency devices need to be designed that don't compromise on the performance that the consumer has come to expect. Class D amplifiers deliver on the goal of increased efficiency, but at the cost of distortion. Class AB amplifiers have low efficiency, but high linearity. By modulating the supply voltage of a Class AB amplifier to make a Class H amplifier, the efficiency can increase while still maintaining the Class AB level of linearity. A 92dB Power Supply Rejection Ratio (PSRR) Class AB amplifier and a Class H amplifier were designed in a 0.24um process for portable audio applications. Using a multiphase buck converter increased the efficiency of the Class H amplifier while still maintaining a fast response time to respond to audio frequencies. The Class H amplifier had an efficiency above the Class AB amplifier by 5-7% from 5-30mW of output power without affecting the total harmonic distortion (THD) at the design specifications. The Class H amplifier design met all design specifications and showed performance comparable to the designed Class AB amplifier across 1kHz-20kHz and 0.01mW-30mW. The Class H design was able to output 30mW into 16Ohms without any increase in THD. This design shows that Class H amplifiers merit more research into their potential for increasing efficiency of audio amplifiers and that even simple designs can give significant increases in efficiency without compromising linearity.
ContributorsPeterson, Cory (Author) / Bakkaloglu, Bertan (Thesis advisor) / Barnaby, Hugh (Committee member) / Kiaei, Sayfe (Committee member) / Arizona State University (Publisher)
Created2013
Description
Class D Amplifiers are widely used in portable systems such as mobile phones to achieve high efficiency. The demands of portable electronics for low power consumption to extend battery life and reduce heat dissipation mandate efficient, high-performance audio amplifiers. The high efficiency of Class D amplifiers (CDAs) makes them particularly attractive for portable applications. The Digital class D amplifier is an interesting solution to increase the efficiency of embedded systems. However, this solution is not good enough in terms of PWM stage linearity and power supply rejection. An efficient control is needed to correct the error sources in order to get a high fidelity sound quality in the whole audio range of frequencies. A fundamental analysis on various error sources due to non idealities in the power stage have been discussed here with key focus on Power supply perturbations driving the Power stage of a Class D Audio Amplifier. Two types of closed loop Digital Class D architecture for PSRR improvement have been proposed and modeled. Double sided uniform sampling modulation has been used. One of the architecture uses feedback around the power stage and the second architecture uses feedback into digital domain. Simulation & experimental results confirm that the closed loop PSRR & PS-IMD improve by around 30-40 dB and 25 dB respectively.
ContributorsChakraborty, Bijeta (Author) / Bakkaloglu, Bertan (Thesis advisor) / Garrity, Douglas (Committee member) / Ozev, Sule (Committee member) / Arizona State University (Publisher)
Created2012
Description
ABSTRACT This study focuses on second language acquisition process amongst East Asian adult learners at an English and Culture Acquisition Program (ECAP) classroom. To understand their English learning experience, this study employs classroom observation, participant interview and document collection as research methods. The findings of this work suggest that ECAP does intend to help learners acquire English language proficiency in ways that were responsive to both the sociocultural backgrounds and individual needs of participants. ECAP also respects and promotes the learners' autonomy in the learning process. However, the program administrators and teachers still need to deepen their understanding of East Asian learners' sociocultural heritage and individual needs and improve facilitation accordingly.
ContributorsMi, Ximin (Author) / Danzig, Arnold (Thesis advisor) / Ovando, Carlos (Committee member) / Szecsy, Elsie (Committee member) / Arizona State University (Publisher)
Created2011
Description
The goals of science and myth go hand in hand. Both seek to see beyond the senses. Both seek to understand the environment and the human mind. Both seek patterns. Both invent, through narrative, reasons for things happening the way they do. This considered, how do writers use myths in contemporary literature? How do they use science? Myth and science are stories that belong to everyone, stories that are shared. For those who are brought up learning science in school or who are raised in a religious society, how can writers take advantage of these shared associations, these shared memories, when writing fiction? What is the power of science in fiction? This essay seeks to answer these questions.
ContributorsDiehl, Dana (Author) / Mcnally, T.M. (Thesis advisor) / Ison, Tara (Committee member) / Pritchard, Melissa (Committee member) / Arizona State University (Publisher)
Created2015
Description
This thesis examines the narratives and meta-commentary of Indonesian users of English about their English as a Second Language (ESL) experiences. It approaches interview data with ten Indonesian second language (L2) speakers of English from a narrative analysis/inquiry perspective. Each interview was transcribed according to a modified set of discourse analysis (DA) transcription conventions, then coded by the researcher. The first research question addressed what linguistic devices members of this population used to achieve cohesion and coherence in their narratives, and the second research question examined how members of this population portrayed their L2 selves in their narratives. The data yielded 21 linguistic devices that fell into three levels of frequency. Connectives, discourse markers, and repetition were by far the most common linguistic devices, followed by adverbials, embedded clauses, intensifiers, and the word like (non-comparison uses), which were somewhat frequent linguistic devices. The data also showed that participants constructed their L2 selves using three main categories: agency, identity, and perceptions of English and the U.S.. In regard to identity, participants invoked membership categorization, where they portrayed their identities in relation to other individuals. The study concludes with suggestions for future research, especially relating to Indonesian L2 users of English.
ContributorsTappendorf, Rebecca C (Author) / Renaud, Claire (Thesis advisor) / Prior, Matthew (Committee member) / Gelderen, Elly van (Committee member) / Arizona State University (Publisher)
Created2015
Description
This study investigates how the teaching English as an international language (TEIL) framework can be integrated into the English curriculum of the Korea Military Academy (KMA). Addressing the research gap on TEIL and military settings, this study first critically reviews issues around the varieties of English (i.e., world Englishes), the international functions of English, and the pedagogical implications of TEIL in today’s globalizing world. The study then examines current challenges and objectives of ELT and suggests practical strategies for incorporating TEIL into the English curriculum of the KMA.
The study suggests the following four strategies to apply TEIL into the English curriculum of the KMA: (a) introduce WE/EIL activities into the English Conversation course; (b) establish a WE/EIL course; (c) provide extracurricular WE/EIL activities; and (d) incorporate intercultural content into the Military English course. The study argues that implementing these suggestions would help cadets develop both their linguistic proficiency in English and intercultural communicative competence that are essential for them to become professional military communicators who can effectively communicate with interlocutors from diverse linguistic, cultural, and national backgrounds in international military contexts.
While the study contributes to the literature by bridging the gap between TEIL and military contexts, it demonstrates the following implications: (a) a meaningful case of applying TEIL into the military context in Korea; (b) the importance of both linguistic proficiency in English and intercultural competence for ELT in the KMA; and (c) the possibility of influencing the Korea Air Force and Naval Academy to reexamine their English curricula. The study concludes that the English curriculum of the KMA should be revised based on the recognition of the symbiotic relationship among linguistic proficiency in English, exposure to diverse varieties of English, and intercultural competence in order to produce cadets who can effectively communicate in English as a military lingua franca for the success of their designated military objectives in the future.
The study suggests the following four strategies to apply TEIL into the English curriculum of the KMA: (a) introduce WE/EIL activities into the English Conversation course; (b) establish a WE/EIL course; (c) provide extracurricular WE/EIL activities; and (d) incorporate intercultural content into the Military English course. The study argues that implementing these suggestions would help cadets develop both their linguistic proficiency in English and intercultural communicative competence that are essential for them to become professional military communicators who can effectively communicate with interlocutors from diverse linguistic, cultural, and national backgrounds in international military contexts.
While the study contributes to the literature by bridging the gap between TEIL and military contexts, it demonstrates the following implications: (a) a meaningful case of applying TEIL into the military context in Korea; (b) the importance of both linguistic proficiency in English and intercultural competence for ELT in the KMA; and (c) the possibility of influencing the Korea Air Force and Naval Academy to reexamine their English curricula. The study concludes that the English curriculum of the KMA should be revised based on the recognition of the symbiotic relationship among linguistic proficiency in English, exposure to diverse varieties of English, and intercultural competence in order to produce cadets who can effectively communicate in English as a military lingua franca for the success of their designated military objectives in the future.
ContributorsJin, Seonghan (Author) / Matsuda, Aya (Thesis advisor) / James, Mark (Committee member) / Prior, Matthew (Committee member) / Arizona State University (Publisher)
Created2019
Description
In this thesis, a digital input class D audio amplifier system which has the ability
to reject the power supply noise and nonlinearly of the output stage is presented. The main digital class D feed-forward path is using the fully-digital sigma-delta PWM open loop topology. Feedback loop is used to suppress the power supply noise and harmonic distortions. The design is using global foundry 0.18um technology.
Based on simulation, the power supply rejection at 200Hz is about -49dB with
81dB dynamic range and -70dB THD+N. The full scale output power can reach as high as 27mW and still keep minimum -68dB THD+N. The system efficiency at full scale is about 82%.
to reject the power supply noise and nonlinearly of the output stage is presented. The main digital class D feed-forward path is using the fully-digital sigma-delta PWM open loop topology. Feedback loop is used to suppress the power supply noise and harmonic distortions. The design is using global foundry 0.18um technology.
Based on simulation, the power supply rejection at 200Hz is about -49dB with
81dB dynamic range and -70dB THD+N. The full scale output power can reach as high as 27mW and still keep minimum -68dB THD+N. The system efficiency at full scale is about 82%.
ContributorsBai, Jing (Author) / Bakkaloglu, Bertan (Thesis advisor) / Arizona State University (Publisher)
Created2015
Description
English proficiency is one of the major factors affecting international students’ academic adjustment to American universities. Many international college students select to improve their academic English proficiency through an English intensive program. Collaborative learning is an educational approach to teaching and learning that allows students and teachers to engage in a common task and work together to search for knowledge and skills. This thesis study aims to develop, design, and iteratively refine strategies to help English intensive program teachers build collaborative learning and promote international students’ effective collaboration, so as to improve students' academic English proficiency. In this study, two different collaborative learning strategies were designed, implemented and iterated. Data was collected using qualitative methods and follow the principle of design-based research (DBR; Barab, 2014) The results of this study suggest that successful instructional strategies for collaborative learning should be designed in the following ways. First, gathering participants’ opinions and feedback at all phases of design and iteration; Second, linking the new strategies or activity to students’ grade should be the center of the design. Third, in DBR，researchers need to be patient to build good relationships with practitioners, which can provide a basis for continuing research.
ContributorsNolastname, Digengni (Author) / Wolf, Leigh Graves (Thesis advisor) / Zuiker, Steven (Thesis advisor) / Lippincott, Dianna (Committee member) / Arizona State University (Publisher)
Created2020
Description
Language Textbooks often play a major role in English for speakers of other languages (ESOL) classrooms, not only to provide information but also to help students construct their identities. Several studies showed that identity and language learning are inseparable, due to the simple fact that every learner has his/her own identity aspects like race, gender, social class, and speaker status (i.e., native speaker vs. non-native speaker of the target language). These aspects should be acknowledged because providing the students with limited identity options might cause the students to resist learning the language or be less invested in this practice (Norton & Toohey,2011).
However, there is limited support for teachers who wish to examine identity in ESOL textbooks. Several scholars attempted to evaluate the range of identity options offered in ESOL textbooks, but they all used either Critical Discourse Analysis or Content Analysis which can be effective; however, these procedures require training and can take a long time, so they may not be practical for teachers. This suggests that there is a need for a less complicated evaluation tool that can be easily used by teachers.
The purpose of this thesis is to develop a teacher-friendly identity-focused checklist for ESOL textbooks, and the thesis is guided by the following questions: (a) what would an evaluation checklist for identity in ESOL textbooks look like?; (b) what can this checklist reveal about ESOL textbooks? The purpose of this thesis was achieved by developing a qualitative checklist that covers, race, gender, social class, and speaker status, and demonstrating how to use it on a collection of five adult ESOL textbooks. The checklist revealed similarities and differences between the textbooks, including important shortcomings, and that kind of information can be useful for the teacher to make decisions about the textbook he/she uses.
However, there is limited support for teachers who wish to examine identity in ESOL textbooks. Several scholars attempted to evaluate the range of identity options offered in ESOL textbooks, but they all used either Critical Discourse Analysis or Content Analysis which can be effective; however, these procedures require training and can take a long time, so they may not be practical for teachers. This suggests that there is a need for a less complicated evaluation tool that can be easily used by teachers.
The purpose of this thesis is to develop a teacher-friendly identity-focused checklist for ESOL textbooks, and the thesis is guided by the following questions: (a) what would an evaluation checklist for identity in ESOL textbooks look like?; (b) what can this checklist reveal about ESOL textbooks? The purpose of this thesis was achieved by developing a qualitative checklist that covers, race, gender, social class, and speaker status, and demonstrating how to use it on a collection of five adult ESOL textbooks. The checklist revealed similarities and differences between the textbooks, including important shortcomings, and that kind of information can be useful for the teacher to make decisions about the textbook he/she uses.
ContributorsAlmatard, Abdulmajeed Mohammed (Author) / James, Mark (Thesis advisor) / Matsuda, Aya (Committee member) / Prior, Matthew (Committee member) / Arizona State University (Publisher)
Created2019
Description
ABSTRACTIn the context of English as a foreign language (EFL) education at Saudi
universities, intrinsic motivation plays a crucial role in the second language (L2) learning
process. Drawing on the theoretical framework of Self-Determination Theory (SDT), this
thesis investigates how learner autonomy can be enhanced to promote intrinsic motivation
among Saudi EFL learners. This thesis offers a literature review to explore the significance
and application of intrinsic motivation proposed by the identified empirical studies in this
context. It begins by providing a general overview of motivation and the relationship
between learner autonomy and intrinsic motivation based on SDT. After that, it explores
the identified studies in this context by providing an in-depth analysis of each study. To
comprehensively review the existing literature, a methodical search strategy was
employed. The Arizona State University Library and the Education Resources Information
Center (ERIC) were utilized. The focus was on empirical studies that emphasized intrinsic
motivation in the context of EFL students in Saudi Arabian universities and how to promote
it, with particular attention to the principles of SDT regarding learner autonomy. It further
suggests that enhancing autonomy, as viewed through the lens of SDT, could provide the
necessary conditions for intrinsic motivation to thrive in the context of EFL in Saudi
Arabia. A justification for this review was the evident gap in the literature as there are only
five identified studies that met the criteria of selection in this context. This thesis contends
that integrating SDT's view of learner autonomy with a balanced approach to structured
and choice-based learning may effectively bridge the gap identified in the current research
on intrinsic motivation. Although the studies at hand present a valuable addition to intrinsic
motivation within the EFL context in Saudi universities, they fall short in some respects.
ii
Therefore, this thesis advocates for an educational model that applies SDT-based
autonomous learning strategies into the curriculum to enrich the intrinsic motivation of
Saudi EFL students. Several recommendations regarding how to promote intrinsic
motivation are presented.
ContributorsBin Mohicen, Abdulaziz (Author) / James, Mark (Thesis advisor) / Prior, Matthew T (Committee member) / Matsuda, Aya (Committee member) / Arizona State University (Publisher)
Created2023