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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
The economic crisis in 2008 triggered a global financial shockwave that left many wondering about the origins of the crisis. Similarly, in the early twentieth century, Wall Street faced catastrophic losses that set the stage for the Great Depression, which resulted in a decade of economic depression, leaving millions of people out of work. Using discourse analysis to understand how economic crisis is framed through the mainstream press, this research project analyzed the stock market crash of 1929-1932 and the mortgage-backed financial crisis of 2007-2009 through the lens of two mainstream publications, The New York Times and The Wall Street Journal. Comparative analysis focused on explanations for the causes of the crises, attributions of blame, culprits, and proposed solutions emerging in news coverage of the 1929 panic and the 2007-2009 financial crises. Mainstream media accounts of the 2007-2009 crisis are then compared with `alternative media' accounts of crisis causes, culprits, and solutions. These comparative analyses are contextualized historically within economic paradigms of thought, beginning with the classical economists led by Adam Smith and transitioning to the Chicago School.
ContributorsPrice, Eun (Author) / Nadesan, Majia (Thesis advisor) / Gruber, Diane (Committee member) / Ramsey, Ramsey E (Committee member) / Arizona State University (Publisher)
Created2013
Description
The ways in which human relationships are managed via language is a topic of particular interest in the area of sociolinguistics where work into the study of such topics as politeness, impoliteness, and rapport management have attempted to shed light on this phenomenon. This study examines two segments of extended discourse by President Alvaro Uribe of Colombia at the 2008 Summit of the Rio Group where he addressed a gathering of Rio Group members comprising heads of state from Latin American and Caribbean nations. Faced with serious accusations about his nation's military actions into Ecuador a few days before the meeting in question, Uribe engaged the group through two extended statements where he defended his government's actions. In these two segments of discourse Uribe changed his tone; it is this change that the present study attempts to describe in terms of modification to the effects of his discourse on the relationship between himself and the other interlocutors. To this end, an analysis is done classifying Uribe's utterances as polite, per Brown and Levinson's politeness model, and impolite, per Culpeper's impoliteness model. Additionally, Spencer Oatey's model of rapport management is used to classify Uribe's utterances according to their effect on the components of rapport. These classifications are examined alongside an analysis of factors related to rapport management such as frame, purpose of the exchange, and participants, for the purpose of understanding how these many factors work together to generate a changed effect to rapport. Of greatest significance in this study is the relationship between (im)politeness strategies and components of rapport. This dynamic provided an interesting way of examining (im)politeness in a new context, one that factored-in the effects of (im)politeness to the relationship between interlocutors. The study, as described above, showed that Uribe's change in tone was indeed a change to approach to rapport management characterized by an initial focus on the transactional and relational goals rapport component in the first of two segments, that then changed in the second part to a focus on face and association rights.
ContributorsBambaren, Anamaria (Author) / García Fernandez, Carmen (Thesis advisor) / Cerron-Palomino, Alvaro (Committee member) / Adams, Karen L. (Committee member) / Arizona State University (Publisher)
Created2011
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
Treating the Pro-Life Movement as a monolithic entity creates a blind spot regarding the cognitive effect of the fetal personhood rhetorical framework. This study applies an interpretive lens, using legal and discourse analysis as tools, to provide a critical analysis of personhood laws and web content to shed light on how linguistic patterns construct, and are informed by, worldview. Examining variations in proposed Human Life Amendments—and asking how, or if, proposed bills achieve their specified aim—reveals tension in state and federal jurisdiction of abortion regulations. It also exposes conflicts concerning tactical preferences for attaining fetal personhood and ending abortion that are useful to differentiating the Pro-Life and Personhood Movements.
Framing and discursive practices of the Personhood Movement reflect a ‘black and white’ mentality and an overly-simplified worldview. Movement cognition is shaped by patterns of omission and exclusion, inclusion, repetition, troubling phrases, and the power of labels. The linguistic choices demonstrate, constitute, and reinforce the dominant narratives of the movement and are integral to advocacy, praxis, and legislative efforts. While the struggle to pass personhood-compliant legislation has not been successful, the rhetorical practices and representational framework of the Personhood Movement have succeeded in altering the national discourse surrounding beginnings of life and abortion. The extreme views of the Personhood Movement reconstitute the middle—making tactics of the mainstream Pro-Life Movement seem moderate and reasonable by comparison, which allows dangerous legislation to slide by under the radar.
Framing and discursive practices of the Personhood Movement reflect a ‘black and white’ mentality and an overly-simplified worldview. Movement cognition is shaped by patterns of omission and exclusion, inclusion, repetition, troubling phrases, and the power of labels. The linguistic choices demonstrate, constitute, and reinforce the dominant narratives of the movement and are integral to advocacy, praxis, and legislative efforts. While the struggle to pass personhood-compliant legislation has not been successful, the rhetorical practices and representational framework of the Personhood Movement have succeeded in altering the national discourse surrounding beginnings of life and abortion. The extreme views of the Personhood Movement reconstitute the middle—making tactics of the mainstream Pro-Life Movement seem moderate and reasonable by comparison, which allows dangerous legislation to slide by under the radar.
ContributorsDay, Sarah Lee (Author) / Behl, Natasha (Thesis advisor) / Mean, Lindsey (Committee member) / Nadesan, Majia (Committee member) / Arizona State University (Publisher)
Created2018
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
This thesis study describes English Language Learner (ELL) participation practices in a summer English language development (ELD) middle school classroom in a public school district in Arizona. The purpose of the study was to document Mexican immigrant and Mexican American English learners' language experiences in a prescriptive ELD program in relation to the social, historical and cultural context. The study utilizes a sociocultural framework and critical language awareness concepts as well as qualitative interpretive inquiry to answer the following research questions: What is the nature of ELL participation during language lessons? That is, what are the common participation practices in the classroom? What social or cultural values or norms are evident in the classroom talk during language lessons? That is, in what ways do participants use language for social purposes? And, what is the cultural model of ELD evident in the classroom language practices? Data collection and analyses consisted of close examination of ELL participation within official language lessons as well as the social uses of language in the classroom. Analysis of classroom discourse practices revealed that ELL participation was heavily controlled within the common Initiation-Response-Evaluation pattern and that the students were limited to repetition and recitation responses. Further, analysis of discourse content demonstrated that classroom participants used language for social purposes in the classroom, most often using regulatory, decontextualized and resistance language. The findings revealed a cultural model of constrained ELD language practices that can be considered a pedagogy of subtractive assimilation.
ContributorsMartinez, Theresa (Author) / Powers, Jeanne M. (Thesis advisor) / Arias, Beatriz (Committee member) / Arzubiaga, Angela (Committee member) / Arizona State University (Publisher)
Created2010
Description
The issue of women driving remains to be highly debated in Saudi Arabia. Recent developments on its legalization have sparked conversation and discourse, particularly in social media sites like Twitter. Several hashtags have been used to indicate either support or criticism towards the movement.
Examining Twitter tweets and hashtags, the study explored how the discourse on women driving had been executed, particularly in between genders. The study analyzed a sizeable number of tweets as well as their context via linguistic corpora analysis. Following Norman Fairclough’s framework, the two opposing perspectives were investigated both at a level of textual analysis. The selected tweets were representative of the three hashtags that emerged on the heat of the discourse regarding the issue of women driving in Saudi Arabia: #Women_car_driving, #I_will_drive_my_car_June15, and #I_will_enter_my_kitchen_June15.
The results showed, among others, that tweets with the hashtag #Women_car_driving presented a tremendous support towards the movement. On the other hand strong opposing reactions emerged from the hashtags #I_will_drive_my_car_June15 and #I_will_enter_my_kitchen_June15.
Examining Twitter tweets and hashtags, the study explored how the discourse on women driving had been executed, particularly in between genders. The study analyzed a sizeable number of tweets as well as their context via linguistic corpora analysis. Following Norman Fairclough’s framework, the two opposing perspectives were investigated both at a level of textual analysis. The selected tweets were representative of the three hashtags that emerged on the heat of the discourse regarding the issue of women driving in Saudi Arabia: #Women_car_driving, #I_will_drive_my_car_June15, and #I_will_enter_my_kitchen_June15.
The results showed, among others, that tweets with the hashtag #Women_car_driving presented a tremendous support towards the movement. On the other hand strong opposing reactions emerged from the hashtags #I_will_drive_my_car_June15 and #I_will_enter_my_kitchen_June15.
ContributorsAljarallah, Rayya Sulaiman (Author) / Adams, Karen (Thesis advisor) / Gelderen, Elly van (Committee member) / Prior, Matthew (Committee member) / Arizona State University (Publisher)
Created2017
Description
This thesis seeks to build upon the empirical use of the Copenhagen School of security studies by evaluating and investigating speech-acts in recent Guatemalan newspaper media as they relate to drug trafficking within the geopolitical borders of Guatemala, particularly induced by Los Zetas, a Mexican drug cartel. The study attempts to engage a critical theoretical framework to study securitization within the country and thereby build upon the theory by conducting real-life analysis. Using a research program that is made up of content and text analysis of national press and presidential speeches, I test several hypotheses that pertain to the processes of Guatemala's current drug trade and drug trafficking securitization. By coding securitizing speech-acts and discursive frames in the national print media, I identify the national elite, the power relations between the national elite and citizenship, and attempts to dramatize the issue of drug trade. Upon analyzing the findings of such securitization, I propose several hypotheses as to why the national elite seeks high politicization of drug trade and the implications that rest on such drastic measures. This thesis itself, then, has important implications: it uses empirical tools to help further the theoretical foundations of the Copenhagen School, it examines the process of securitization study from a real world context outside the developed world, and it presents important information on the possible consequences of securitizing drug trade.
ContributorsBrinkmoeller, Matthew (Author) / Doty, Roxanne (Thesis advisor) / Gortzak, Yoav (Committee member) / Jones, Ruth (Committee member) / Arizona State University (Publisher)
Created2011