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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
Principles of climate mitigation in environmental ethics often draw on either considerations of fairness and forward-looking concerns, or on justice and backward-looking concerns. That is, according to some theorists, considerations of the current distribution of climate benefits and burdens are foremost, while others take repairing historic wrongs as paramount. Some theorists integrate considerations of fairness and justice to formulate hybrid climate principles. Such an integrative approach is promising particularly in the context of environmental harm to indigenous subsistence peoples, who are among those suffering the most from climate change. I argue that existing integrative climate principles tend not to sufficiently emphasize considerations of backward-looking justice. This is a problem for indigenous peoples seeking reparations for environmental harm and violations of their human rights. Specifically, indigenous people in the Arctic suffer a cultural harm from climate change as they lose their land, and their way of life, to erosion, cementing their status as climate refugees. I argue that the current climate situation facing Native Arctic people is unfair according to Rawls' second principle of justice. In addition, the situation is unjust as indigenous people suffer from emissions by others and few attempts are made for reparations. Thus, Rawlsian fairness combined with reparative justice provide a befitting theoretical framework. I conclude that an acceptable climate principle will adequately integrate considerations of both fairness and justice, both forward-looking and backward-looking considerations.
ContributorsSweetland, Lauren (Author) / Brake, Elizabeth (Thesis advisor) / Tsosie, Rebecca (Committee member) / Portmore, Douglas (Committee member) / Arizona State University (Publisher)
Created2014
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
Mexico City has an ongoing air pollution issue that negatively affects its citizens and surroundings with current structural disconnections preventing the city from improving its overall air quality. Thematic methodological analysis reveals current obstacles and barriers, as well as variables contributing to this persistent problem. A historical background reveals current programs and policies implemented to improve Mexico’s City air quality. Mexico City’s current systems, infrastructure, and policies are inadequate and ineffective. There is a lack of appropriate regulation on other modes of transportation, and the current government system fails to identify how the class disparity in the city and lack of adequate education are contributing to this ongoing problem. Education and adequate public awareness can potentially aid the fight against air pollution in the Metropolitan City.
ContributorsGarcia, Lucero (Author) / Duarte, Marisa E. (Thesis advisor) / Arzubiaga, Angela (Committee member) / Richter, Jennifer (Committee member) / Arizona State University (Publisher)
Created2018
Description
Sustainability and environmental justice, two fields that developed parallel to each other, are both insufficient to deal with the challenges posed by institutional environmental violence (IEV). This thesis examines the discursive history of sustainability and critiques its focus on science-based technical solutions to large-scale global problems. It further analyzes the gaps in sustainability discourse that can be filled by environmental justice, such as the challenges posed by environmental racism. Despite this, neither field is able to contend with IEV in a meaningful way, which this thesis argues using the case study of the Flint Water Crisis (FWC). The FWC has been addressed as both an issue of sustainability and of environmental justice, yet IEV persists in the community. This is due in part to the narrative of crisis reflected by the FWC and the role that knowledge production plays in that narrative. To fill the gap left by both sustainability and environmental justice, this thesis emphasizes the need for a transformational methodology incorporating knowledge produced by communities and individuals directly impacted by sustainability problems.
ContributorsWest, Madison Sedona (Author) / Graffy, Elisabeth (Thesis advisor) / Klinsky, Sonja (Committee member) / Broberg, Gregory (Committee member) / Arizona State University (Publisher)
Created2019
Description
The Santa Cruz River Basin shared by Northern Sonora and Southern Arizona is one example of transboundary water resources in the borderlands region that accurately portrays the complexities of binational management of common pool resources, such as water. Industrialization fueled by trade liberalization has resulted in migration to and urbanization along the border, which have created human rights issues with the lack of water and sanitation, groundwater overdraft of the shared aquifers, and contamination of these scarce resources. Effluent from wastewater treatment plants continues to play increasingly important roles in the region, the use of which has been a source of tension between the two countries. Contributing to these tensions are the strains on binational relations created by border militarization and SB 1070. A shift in water management strategies to increase pubic participation within decision-making, increase the flexibility of the water systems, and increase cross-border collaboration is needed to ensure human and ecological sustainability in the Santa Cruz River Basin. By incorporating direct communication and local capacity as per common pool resource theory, recognizing the connections and implications of management actions through socio-ecological systems understanding, and promoting the organic drivers of change through ecologies of agents, just and vigorous futures can be envisioned and advanced.
ContributorsEppehimer, Drew (Author) / Haglund, LaDawn (Thesis advisor) / Richter, Jennifer (Committee member) / Smith, Karen (Committee member) / Arizona State University (Publisher)
Created2015
Description
It is widely recognized that, compared to others, minority and low-income populations are more exposed to environmental burdens and unwanted land uses like waste facilities. To prevent these injustices, cities and industry need to recognize these potential problems in the siting process and work to address them. I studied Phoenix, AZ, which has historically suffered from environmental justice issues. I examined whether Phoenix considered environmental justice concerns when siting their newest landfill (SR-85) and transfer station (North Gateway Transfer Station). Additionally, I assessed current views on sustainability from members of the Phoenix Transportation and Infrastructure Subcommittee and of decision-makers in the Public Works Department and Solid Waste Division. Using a mixed methods approach consisting of interviews, document analysis, and a demographic assessment of census tracts, I addressed two main research questions:
1. Do the distributions and siting processes of environmental burdens from SR-85 and North Gateway Transfer Station constitute a case of environmental injustice according to commonly held definitions?
2. Do current Solid Waste and council members on the Transportation and Infrastructure subcommittee consider environmental justice, defined as stakeholder engagement, to be a part of sustainability?
The results show that the distribution and siting processes of environmental burdens from these facilities may constitute a case of environmental injustice. While city officials do involve stakeholders in siting decisions, the effects of this involvement is unclear. An analysis of long-term demographic data, however, revealed no significant racial, ethnic, or economic effects due to the locations of the SR-85 and North Gateway Transfer Station.
Interviews with current members of the Transportation and Infrastructure Subcommittee, Public Works Department, and Solid Waste Division indicated that Phoenix’s decision-makers don’t consider environmental justice as part of sustainability. However, they seem to consider stakeholder engagement as important for decision-making.
To help mitigate future injustices, Phoenix needs buffer zone policies for waste facilities and stakeholder engagement policies for decision-making to ensure the public is engaged appropriately in all circumstances. Enacting these policies will help Phoenix become both a more sustainable city and one in which stakeholders have the opportunity to provide feedback and are given decision-making power.
1. Do the distributions and siting processes of environmental burdens from SR-85 and North Gateway Transfer Station constitute a case of environmental injustice according to commonly held definitions?
2. Do current Solid Waste and council members on the Transportation and Infrastructure subcommittee consider environmental justice, defined as stakeholder engagement, to be a part of sustainability?
The results show that the distribution and siting processes of environmental burdens from these facilities may constitute a case of environmental injustice. While city officials do involve stakeholders in siting decisions, the effects of this involvement is unclear. An analysis of long-term demographic data, however, revealed no significant racial, ethnic, or economic effects due to the locations of the SR-85 and North Gateway Transfer Station.
Interviews with current members of the Transportation and Infrastructure Subcommittee, Public Works Department, and Solid Waste Division indicated that Phoenix’s decision-makers don’t consider environmental justice as part of sustainability. However, they seem to consider stakeholder engagement as important for decision-making.
To help mitigate future injustices, Phoenix needs buffer zone policies for waste facilities and stakeholder engagement policies for decision-making to ensure the public is engaged appropriately in all circumstances. Enacting these policies will help Phoenix become both a more sustainable city and one in which stakeholders have the opportunity to provide feedback and are given decision-making power.
ContributorsGarland, P. M. (Patricia M.) (Author) / Golub, Aaron (Thesis advisor) / Boone, Christopher (Committee member) / Kim, Yushim (Committee member) / Arizona State University (Publisher)
Created2015
Description
The natural environment is becoming an increasing concern within the global society and within the realm of social work practice. Social work practitioners and scholars are advocating for incorporating environmental justice into social work education, but have yet to adequately develop the research and strategies to execute this task. To further develop the research behind this concept, 112 social work students’ attitudes toward the environment were analyzed using the New Environmental Paradigm Scale and questions regarding the intersection of social work and the natural environment. Analysis of the data found social work students were less pro-environment than populations within previous studies. Although, social work students reported the desire to learn more about environmental issues and felt as though it would help them become better social workers. Results also suggested social work students did not know where to find information on environmental issues and misconstrued information on environmental issues, whether or not they felt informed. It will be imperative to further develop the research on incorporating environmental justice into social work education through future pilot programs with student attitudes and cultures into consideration.
ContributorsJung, Christine B (Author) / Androff, David (Thesis advisor) / Bonifas, Robin (Committee member) / Krysik, Judy (Committee member) / Arizona State University (Publisher)
Created2016
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 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