Matching Items (13)
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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
Transformation Is... is an arts practice-led research in Dance and Design, embodying and materializing concepts of structure, leadership and agency and their role in bringing about desired social transformation. My personal experiences as a foreign student interested in transformative experiences gave origin to this arts practice-led research. An auto-ethnographic approach informed by grounded theory methods shaped this creative inquiry in which dance was looked at as data and rehearsals became research fields. Within the context of social choreography, a transformational leadership style was applied to promote agency using improvisational movement scores to shape individual and collective creative explorations. These explorations gave birth to a flexible and transformable dance installation that served as a metaphor for social structure. Transformation revealed itself in this research as a sequence of process and product oriented stages that resulted in a final performance piece in which a site-specific interactive installation was built before the audience's eyes. This work became a metaphor of how individual actions and interactions effect the construction of social reality and how inner-transformation and collaboration are key in the process of designing and building new egalitarian social structures.
ContributorsSibauste Bermudez, Janelle (Author) / Kaplan, Robert (Thesis advisor) / Britt, Melissa (Committee member) / Standley, Eileen (Committee member) / Arizona State University (Publisher)
Created2014
Description
This paper is seeking to use exploratory factor analysis to construct a numeric representation of Hill Collin's matrix of domination. According to Hill Collins, the Current American matrix of domination, or the interlocking systems of oppression, includes race, gender, class, sexual orientation, religion, immigration status, disability, and age. The study uses exploratory factor analysis to construct a matrix of domination scale. The study launched an on-line survey (n=448) that was circulated through the social network Facebook to collect data. Factor analysis revealed that the constructed matrix of domination represents an accurate description of the current social hierarchy in the United States. Also, the constructed matrix of domination was an accurate predictor of the probability of experiencing domestic abuse according to the current available statistics.
ContributorsAzab, Marian (Author) / Quan, H. L. T. (Thesis advisor) / Keil, Thomas (Committee member) / Stancliff, Michael (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
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
The Arizona Interfaith Alliance for Worker Justice (AIAWJ) was a mediating structure for those who wanted to be civically engaged in the labor movement and other coalitions in Phoenix, Arizona. It not only served its constituents, but it integrated, educated, and empowered them. Due to lack of funding the AIAWJ closed in the summer of 2016. Many community members from marginalized neighborhoods, other concerned citizens, students, myself, and others participated in their first and only civic engagement opportunities through this organization and were subsequently left with no connections, a barrier to being civically engaged. Through interviews and secondary data research, the relationship between people, mediating structures, and civic engagement activity are examined. The key findings support existing research that emphasizes the importance of mediating structures when it comes to civic engagement.
ContributorsSickler, Shawn (Author) / Luna, Ilana (Thesis advisor) / Hager, Mark (Committee member) / Keahey, Jennifer (Committee member) / Arizona State University (Publisher)
Created2016
Description
The modern food system unsustainably produces both a food surplus and record levels of hunger. Capitalist investment into agriculture disrupted natural cycles and social relations. Marx’s concept of the metabolic rift describes the way capitalist agriculture actively deteriorates the ecology (ecological rift) and disenfranchises people from food (social rift) are traced on the global scale. Then these rifts are deeply explored on the local scale of Maricopa County, Arizona to reveal the ways that even local food systems are enmeshed within the global capitalist agricultural food system. Phoenix, AZ, located in Maricopa County, has made commitments to become equitable and sustainable by 2050 in part to address issues facing the local food system. Efforts to achieve this goal (policies and studies) are analyzed using the frameworks of sustainable development (dominant “green”/ market based sustainability) and just sustainabilities (disruptive/ justice oriented sustainability). These frameworks help determine whether local efforts mend the ecological and social rifts created by capitalist agriculture, or actively deepen them. While a few studies may attempt “sustainable” solutions, they may in fact further entrench local agriculture in an unsustainable globalized food system. The efforts that are able to address both rifts, challenging the logic and structures of capitalist agriculture, are lacking in scale. In order for Phoenix to reach its sustainability goals by 2050, the ecological and social rifts must be addressed together. To do this, residents and policy makers must be able to determine between efforts that toy at the edges of capitalist agriculture and those with transformational potential, as they challenge the structures and logic of capitalism, ultimately mending the metabolic rift. While this is being done on a small scale, much more is needed to achieve a truly just and sustainable food system.
ContributorsLomelin, Marcelo Fabian (Author) / Perkins, Tracy (Thesis advisor) / Haglund, LaDawn (Committee member) / Adamson, Joni (Committee member) / Arizona State University (Publisher)
Created2022
Description
ABSTRACT
This research analyzes the testimonies of eleven women survivors of state terrorism and genocide from several different regions of the world in an effort to glean the patterns that emerge from their lived experiences. Women often have been targeted and used instrumentally in political violence by states. Yet, when it comes to nation-building, national narratives and identities, their voices are excluded. Data were collected from archival interviews with women survivors and one case-study interview conducted with a survivor recruited for this study, as a cross-check backdrop to compare similarities and differences in contexts and experiences. Four dominant themes appear to emerge across interviews: gendered violence; internalization/reproduction of gender roles; identity relationship to national narrative; and perception of perpetrators. The case-study participant interview revealed disconfirming evidence across themes, suggesting that sense of belonging may be an important facet of national identity which needs further exploration. Relationships between women’s experiences of state terror, genocide, national narrative construction, and nation-building are examined. Suggestions for future research include the need for expanded survivor demographic information, increased in-person interviews, and similar work centered on women perpetrators of state terror and genocide, as well as men’s experiences of state terror and genocide. Keywords: state terrorism; genocide; women; gender; nation-building; social hierarchy
ContributorsMoio-Johnson, Hadley (Author) / Oliverio, Annamarie (Thesis advisor) / Lauderdale, Pat (Committee member) / Yellow Horse, Aggie (Committee member) / Arizona State University (Publisher)
Created2022
Description
For over a century, it has been commonly observed that the pace-of-life in modern society appears to be significantly faster than in non-modern societies, but exactly what forces drive these differences continue to be both hotly debated and difficult to study. While prior studies on pace-of-life have focused on population-level correlations between these factors and pace-of-life, they provide few details about how changes to pace-of-life associated with modernity actually occur in context. This study addresses the issue from a historical perspective, attempting to identify what factors are relevant to a change of pace-of-life in a non-modern to modern lifestyle transition over a single lifetime. This study performs a historical analysis, examining changes in pace-of-life experienced by students of the Carlisle Indian Industrial School, an Indian residential school operating in the late 19th and early 20th centuries, as compared to the non-modern lifestyle of the Plains Indian Cultures from the same time period. This study finds that the pace-of-life experienced by students at Carlisle were consistently faster, more intense and more regimented than in non-modern lifestyles. Such changes in pace-of-life were driven in large part by efforts of the school to transform the students behavior into a model the administration considered more suited to life in a modern society, chiefly, time-disciplined, individualistic, future oriented and competitive laborers. This case highlights that the role of individual behavioral manipulation by large-scale institutions is an underappreciated force in changes to pace-of-life in modern society.
ContributorsCoffey, Michael (Author) / Connor, Dylan (Thesis advisor) / Turner, Billie L (Committee member) / DesRoches, Tyler (Committee member) / Arizona State University (Publisher)
Created2021
Description
The purpose of this study is to examine the influence of neoliberalism on the occurrence and intervention of genocide, particularly the ability to create othered groups through a process of dehumanization that desensitizes those in power to the human condition. I propose Social Externalization Theory as paradigm that explains how neoliberalism can be used as a means social control to create subjects vulnerable to political and collective violence that is justified as the externalized cost of economic growth, development, and national security. Finally, the conflict in Darfur (2003 - 2010) serves as a case study to analyze the influence of neoliberal policies on the resistance of the International community to recognize the violence as genocide. Analysis of the case study found that some tenets of neoliberalism produce results that fit within the ideologies of genocide and that some aspects of neoliberalism assume a genocidal mentality. In this case, those in positions power engage in daily activities that justify some suffering as acceptable, thus desensitizing them to the harm that their decisions generate.
ContributorsCalleja, Robert J (Author) / Romero, Mary (Thesis advisor) / Swadener, Beth Blue (Committee member) / Schugurensky, Daniel, 1958- (Committee member) / Arizona State University (Publisher)
Created2013