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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 relationship between parent and child acculturation gaps and the child's well-being for Asian American families, with the child's perceived family conflict as a potential mediating variable were examined in this study. In addition to linear relationships of acculturation gaps, curvilinear relationships were also examined. The sample consisted of 165 first or second generation Asian Americans, aged between 18 to 22. Results indicated that native culture gap is predictive of participants' self-report of depression, and family conflict did function as a mediator to the relationship between native culture gap and depression. The curvilinear relationship between acculturation gaps and well-being was not supported by the results of the study. Further implications and future directions are discussed.
ContributorsShi, Yue (Author) / Tracey, Terence (Thesis advisor) / Homer, Judith (Committee member) / Atkinson, Robert (Committee member) / Arizona State University (Publisher)
Created2015
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
Humans are social beings, which means interpersonal relationships are important contributors to our psychological health. Our health and behavior is manifested through a dynamic cycle of interacting factors: environmental, personal, and behavioral. Contributing to this interaction, interpersonal relationships provide benefits such as increased social support and decreased loneliness. The care and attention of relationship partners are communicated in multiple ways, one of which is interpersonal touch. Although touch can communicate positive feelings and support, it can also be used negatively in certain contexts. Unwanted or forced touch occurs when an individual experiences sexual or physical trauma. Experiencing this type of trauma often results in negative psychological consequences. Exactly how sexual or physical trauma—both of which involve unwanted touch—might influence an individual’s attitudes towards touch is important to explore. If an individual feels negatively about interpersonal touch due to previous experience of trauma, this might negatively influence the amount of current touch with a partner, and also the survivor’s psychological well-being.
In the current study, I proposed that previous occurrence of sexual or physical trauma would predict both decreased frequency of touch in a current intimate relationship and poorer individual well-being, and that these relations would be explained by negative touch attitudes. Results supported these hypotheses, suggesting that lingering negative touch attitudes following trauma could be an underlying mechanism affecting social and individual functioning. As seen in our model, these attitudes fully mediated the effects between previous sexual or physical trauma and individual well-being, as well as frequency of touch. This understanding can help provide further insight into the repercussions of trauma and the underlying mechanisms attributing to continued negative effects.
In the current study, I proposed that previous occurrence of sexual or physical trauma would predict both decreased frequency of touch in a current intimate relationship and poorer individual well-being, and that these relations would be explained by negative touch attitudes. Results supported these hypotheses, suggesting that lingering negative touch attitudes following trauma could be an underlying mechanism affecting social and individual functioning. As seen in our model, these attitudes fully mediated the effects between previous sexual or physical trauma and individual well-being, as well as frequency of touch. This understanding can help provide further insight into the repercussions of trauma and the underlying mechanisms attributing to continued negative effects.
ContributorsHurd, Julie Ann (Author) / Burleson, Mary H (Thesis advisor) / Roberts, Nicole A. (Committee member) / Miller, Paul A. (Committee member) / Arizona State University (Publisher)
Created2018
Description
Previous studies about well-being have examined either gratitude’s or social connectedness’ relationship to subjective well-being. The aim of this randomized control trial was to examine the efficacy of a gratitude-based writing micro-intervention in enhancing felt social connectedness and well-being between young adults and their parents. The trial tested the impact of engaging in gratitude-based writing about family members or enhanced caretakers on measures of social connectedness and well-being between grown children and their parents. Data from a pool of social work students in the Southwest (N=148) were used. Results revealed within-subject effects and between subject effects for psychological well-being from pretest to one month follow-up, with the intervention group reporting significantly higher psychological well-being than the control group. Results also revealed slight mean differences from pretest to posttest for perceptions of family relationships, with the intervention group reporting approaching significant better perceptions of family relationships than the control group at posttest. Findings from the study indicate that engaging in gratitude-based writing about family can improve perceptions of psychological well-being and may improve social connectedness to family.
ContributorsKaplan, Tamar (Author) / LeCroy, Craig W. (Thesis advisor) / Williams, Lela R (Committee member) / Brown, Mary Ellen (Committee member) / Arizona State University (Publisher)
Created2018
Description
Art is a form of spiritual expression that is thriving in many Indigenous cultures. It can take many forms, meanings and have a multitude of emotional, mental, physical and spiritual effects on its creator as well as its audience. Amongst American Indians, art has been a method for maintaining holistic well-being intended to heal and cope with traumatic experiences. In this thesis, I examine the western societal and cultural influences that have led to the loss of cultural identity and examine approaches and practices that aim to re-establish a resilient connection to identity and well-being using art as a spiritual catalyst. Literary research and articles were reviewed related to the issue of art as a form of spiritual expression in Indigenous cultures. An autoethnography was conducted with the intent to record and reflect on the well-being of the researcher in relation to her artistic expression. Journaling and vlogging were used as research methods and painting, sketching, and beading was used as artistic methods. Over the course of six months, over 50 videos with 30 hours of raw footage were recorded; averaging 2 hours per day. The results are reflected in the researchers free-flowing and emotionally driven reflection of experiences that have driven her artwork. This thesis supports the establishment of art as a form of spiritual expression for transforming the current western focused health care paradigm to one that recognizes, values and employs Indigenous insight, methodologies, worldviews, culture and spirituality.
ContributorsRobbins, Marlena (Author) / Romero-Little, Eunice (Thesis advisor) / Marley, Tennille L (Committee member) / Meders, Jacob (Committee member) / Arizona State University (Publisher)
Created2018
Description
There is limited research on bullying among college students and even less research on hazing behaviors among students who are in a campus organization. Previously used scales were created for use with children and were not behavior specific, leaving out adult experiences college students may encounter and asking about bullying in general which leaves the definition up to the responder. This study aimed to create an instrument that examines behavior specific experiences with college students and their peers, in the general college setting and specific to a campus organization they belong to. Five hundred and two undergraduate students completed surveys of college experiences, affect, and well-being. Results indicate one factor for college bullying and one factor for hazing in college organizations. Bullying and hazing were found to be similar but different, with students having more experiences with bullying and the two experiences having different relations to affect and well-being. This study lends to the growing literature on bullying experiences of adults and begins the necessary evaluation of hazing in college organizations.
ContributorsDimberg, Sierra Kelsey (Author) / Tracey, Terence (Thesis advisor) / Kochenderfer-Ladd, Becky (Thesis advisor) / Robinson-Kurpius, Sharon (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
Numerous psychosocial and health factors contribute to perceived stress, social support, and problem-solving coping relating to overall well-being and life satisfaction in older adults. The effect of social support and problem-solving coping, however, remains largely untested as potential moderators. The present study was conducted to test whether social support and problem- solving coping would moderate the relation between perceived stress and life satisfaction in older adults. First, I anticipated that stress will be negatively related to life satisfaction at low levels of social support, while at high social support; stress will be unrelated to life satisfaction. Second, I expected that with low problem- solving coping, stress will be negatively related to life satisfaction, whereas, at levels of high problem- solving coping, stress will be unrelated to life satisfaction. Using an experimental survey and interview design with hierarchical regression analyses, I found no support that social support would moderate the relation between stress and life satisfaction. I found support that problem-solving coping moderated the relation between stress and life satisfaction. For individuals who engage in higher levels of problem- solving coping, higher levels of stress predicted lower levels of life satisfaction. On the other hand, at lower levels of problem-solving coping, more stress predicted lower levels of life satisfaction.
ContributorsKaur, Gurjot (Author) / Miller, Paul A. (Thesis advisor) / Hall, Deborah L. (Committee member) / Roberts, Nicole A. (Committee member) / Arizona State University (Publisher)
Created2017
Description
Life satisfaction in people with physical disabilities is on average lower than people without disabilities. This reduction in life satisfaction may be due to a reduction in domain control. This study examines how domain control predicts life satisfaction when added to a model of other salient life satisfaction predictors. Using email survey methodology, five separate scales where used on two separate populations; people with (n= 44) and without (n= 43) a physical disability to determine each groups life satisfaction. It was found that when domain control is added to the bottom-up theory of life satisfaction, the independent direct relationships of domain control, domain importance, positive affect, and negative affect are eliminated from a stepwise multiple regression equation with domain satisfaction being the only significant predictor (â = 4.38, p< .001 for people with a physical disabilities and â = 5.48, p< .001 for people without a physical disability) of life satisfaction. The study results demonstrate that life satisfaction is predicted the same way for people with and without disabilities.
ContributorsCasto, Joseph (Author) / Rodriuez, Ariel (Thesis advisor) / Grossman, Gary (Committee member) / Ramella, Kelly (Committee member) / Arizona State University (Publisher)
Created2010