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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
Playing tennis professionally is a stressful profession. However, it has the potential to be even more stressful for players who must move from their home country in order to train. If not dealt with, these stresses have the potential of causing many negative outcomes, including increasing levels of distress, in these professional tennis players. It is known that resources play a role in reducing or buffering levels of stress and distress among individuals, but there are competing theories as to how this occurs. Using Ensel and Lin's models of stress processes, this is an exploratory study that identifies the stresses and distresses professional Taiwanese tennis players face and the resources they use to cope. Participants included in this study are professional Taiwanese tennis players (2 males and 2 females) who continuously attend national and international tennis competitions and have both domestic and world ranks. Results from the semi-structured interviews revealed that challenges, frustration, resources, and toughness were four general themes to describe stresses and distresses professional Taiwanese tennis players face and the resources they use to cope. Future research for professional tennis players is also discussed.
ContributorsHung, Wei-Hsia (Author) / Rodriguez, Ariel (Thesis advisor) / Chuang, Shu-Tzu (Committee member) / Budruk, Megha (Committee member) / Hager, Mark A. (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
Resettled refugees face numerous challenges including unsafe living conditions, loss of permanent shelter, adjustment to a new culture, loneliness, and separation from family, friends, and community. Of particular importance is the lack of a feeling of sense of community (SOC) within their new surroundings. SOC is not only worthwhile as an outcome of its own, but may also predict additional positive outcomes such as resilience and cultural adjustment. Literature has shown participation in sport can develop youth positively and build social skills, while studies in other regions of the world have also found a sport team setting to be a place for immigrants to experience SOC. In this study, I use a congruent mixed methods approach to both explore the experience of SOC for youth refugees in a soccer club, and examine the relation of SOC to resilience and cultural adjustment. Using photo-elicitation and semi-structured interviews with 11 youth participants, the qualitative portion of the study explored SOC among youth participants. Findings note the presence of SOC as matched to theoretical frameworks both specific to sport, and to a more general theory of SOC. Further data were collected through questionnaires distributed to club members. Results from the quantitative analysis indicate a significant positive relation between SOC and resilience, and SOC and perceived acculturation. This study’s contribution is to illustrate how refugee youth in a sport club in the United States experience SOC, and the impact of that SOC. Results suggest practical implications for sport managers who wish to provide positive sport experiences for youth refugees.
ContributorsFader, Nina (Author) / Legg, Eric (Thesis advisor) / Larsen, Dale (Committee member) / Klimek, Barbara (Committee member) / Arizona State University (Publisher)
Created2018
Description
ABSTRACT
Elite experience and careers in judged female sports complicate the binary categories of retirement while they are especially exposed to cultures of abuse, pressure and subjectivity. This thesis is comprised of multiple voices and experiences from the elite female athletic perspective, including my autoethnographic narrative. Highlighted and discussed are the topics of sexual assault and abuse, family pressure on children to do and excel at sport, the National Team experience representing the United States and subjected bodies and judging. It is an aim of this thesis to culminate all of those factors in the final chapter and hold that the experience and the cultures of athletic identity within synchronized swimming, gymnastics and figure skating not only cannot be explained by current research on athletic identity through retirement but have the capability to retire undeveloped young women by overdeveloped athletic identities. Through a sampling of voices and experiences across different female judged sports, over three decades, the reader will observe similarities that cause these sports to have a culture of solidarity through the aspects they hold in common with each other. The narrative highlights pivotal moments in the lives of the elite female athlete within these sports, which add to the calculation of their athletic identities and the lack of their personal identities. Through reflection and analyses of not only my story, but the interviewees from my original research and that of Joan Ryan’s as well, I aim to voice a mutual experience of elite athletes. Consisting of multiple factors throughout many years we will see through my autoethnography, paralleling with other voices and experiences, how it all intersects and contributes to this: Who am I now and where do I go from here?
Elite experience and careers in judged female sports complicate the binary categories of retirement while they are especially exposed to cultures of abuse, pressure and subjectivity. This thesis is comprised of multiple voices and experiences from the elite female athletic perspective, including my autoethnographic narrative. Highlighted and discussed are the topics of sexual assault and abuse, family pressure on children to do and excel at sport, the National Team experience representing the United States and subjected bodies and judging. It is an aim of this thesis to culminate all of those factors in the final chapter and hold that the experience and the cultures of athletic identity within synchronized swimming, gymnastics and figure skating not only cannot be explained by current research on athletic identity through retirement but have the capability to retire undeveloped young women by overdeveloped athletic identities. Through a sampling of voices and experiences across different female judged sports, over three decades, the reader will observe similarities that cause these sports to have a culture of solidarity through the aspects they hold in common with each other. The narrative highlights pivotal moments in the lives of the elite female athlete within these sports, which add to the calculation of their athletic identities and the lack of their personal identities. Through reflection and analyses of not only my story, but the interviewees from my original research and that of Joan Ryan’s as well, I aim to voice a mutual experience of elite athletes. Consisting of multiple factors throughout many years we will see through my autoethnography, paralleling with other voices and experiences, how it all intersects and contributes to this: Who am I now and where do I go from here?
ContributorsHaylor, Alyson (Author) / Colbern, Allan (Thesis advisor) / Mean, Lindsey (Committee member) / Kassing, Jeffrey (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
Athletes and sports seem impervious to criticism. Sports is one of the most popular forms of entertainment within popular culture. Since popular culture is one of the dominant forms of education, it is important to analyze and recognize the ideologies present. How do the images and portrayals of professional athletes in still images and video endorsements reflect and perpetuate hegemonic ideologies of race and gender? How do these portrayals intersect with issues of justice and representation? By using a cultural studies framework with emphasis on representation of race and gender in popular culture, an analysis of the representation of seven athletes in advertising for endorsements was conducted. The seven athletes were chosen based on name-recognition, popularity, success in their sport, and a need for a diversity of races and gender. Using semiotics, the advertisements were coded and themes were presented. Several themes presented in the advertisements: Including (1) white female athletes are presented as sexualized objects, (2) black female athletes are represented using masculine traits, (3) white male athletes are normalized, and (4) black male athletes are presented as successful because of their bodies. These representations are harmful because they do little to nothing to change dominant ideologies. The representation of athletes in advertising reinforce hetero-patriarchal ideologies of race and gender.
ContributorsWeiler, Erika (Author) / Sandlin, Jennifer (Thesis advisor) / Rashad Shabazz Sanders, Gregg (Committee member) / Henderson, Deborah (Committee member) / Arizona State University (Publisher)
Created2016
Description
The fitness and wellness industry is expanding at a rapid pace, and part of this expansion includes wellness tourism. Within wellness tourism, fitness related activities and programs are sought by wellness tourists or more specifically, fitness tourists. Wellness tourism is defined as a journey by people whose motive, in whole or in part, is to maintain or promote their well-being, and who stay at least one night at a facility that is designed to enable and enhance physical, psychological, spiritual and/or social well-being. Inevitably, fitness related activities are offered within wellness tourism, and seem to attract these fitness tourists.
The purpose of this study is two-fold. It is first to examine the goal content fitness tourists possess in this non-traditional exercise context. Second, this study aims to examine the goal pursuits within the promotional content produced by the wellness tourism industry. This study is informed by goal content theory (GCT) which is a mini-theory within self-determination theory (SDT). Developed by Kasser and Ryan (1996), GCT examines how goals pursued by individuals, in this case fitness tourists, whether related to extrinsic or intrinsic content, account for variations in wellness. Extrinsic goals include elements like wealth and appearance, while intrinsic goals include dimensions like community contribution and health management.
Participants were targeted through their consumption of fitness services at wellness tourism resorts in the southwestern United States. The goal content for exercise questionnaire (GCEQ) was distributed to these targeted participants to determine the types of exercisers, intrinsically or extrinsically motivated, who are consuming these services. Additionally, a content analysis was conducted to examine the elements portrayed by the industry within a fitness context. Understanding goal content can allow organizations to create programs supportive of participants’ autonomous motivations which research suggests lead to higher levels of well-being. Using a sample of 100 GCEQs, the study implies fitness tourists are more likely to be white, high income females with stronger intrinsic goal content. Health management, image, and skill development were among the highest ranked goals. A total of 182 images were examined in addition to extensive narrative content on the webpages of these sites suggesting this industry promotes holistic wellness rather than appearance. The results of this study should be used to program physical activity interventions made accessible to low and middle class individuals.
The purpose of this study is two-fold. It is first to examine the goal content fitness tourists possess in this non-traditional exercise context. Second, this study aims to examine the goal pursuits within the promotional content produced by the wellness tourism industry. This study is informed by goal content theory (GCT) which is a mini-theory within self-determination theory (SDT). Developed by Kasser and Ryan (1996), GCT examines how goals pursued by individuals, in this case fitness tourists, whether related to extrinsic or intrinsic content, account for variations in wellness. Extrinsic goals include elements like wealth and appearance, while intrinsic goals include dimensions like community contribution and health management.
Participants were targeted through their consumption of fitness services at wellness tourism resorts in the southwestern United States. The goal content for exercise questionnaire (GCEQ) was distributed to these targeted participants to determine the types of exercisers, intrinsically or extrinsically motivated, who are consuming these services. Additionally, a content analysis was conducted to examine the elements portrayed by the industry within a fitness context. Understanding goal content can allow organizations to create programs supportive of participants’ autonomous motivations which research suggests lead to higher levels of well-being. Using a sample of 100 GCEQs, the study implies fitness tourists are more likely to be white, high income females with stronger intrinsic goal content. Health management, image, and skill development were among the highest ranked goals. A total of 182 images were examined in addition to extensive narrative content on the webpages of these sites suggesting this industry promotes holistic wellness rather than appearance. The results of this study should be used to program physical activity interventions made accessible to low and middle class individuals.
ContributorsJohnson, Courtney Paige (Author) / Buzinde, Christine N. (Thesis advisor) / Nyaupane, Gyan P. (Committee member) / Ransdell, Lynda B. (Committee member) / Arizona State University (Publisher)
Created2017
Description
The human body has temperature-regulating mechanisms working to maintain body core temperature around 37°C. This ensures optimal bodily function. Disruption to core temperature however, initiates a cascade of events to return to baseline. The objective of this study is to evaluate the efficacy of cooling strategies to induce the fastest reductions in core temperature. The study was set up as a randomized field study. Core temperature was measured using an E-Celsius core temperature capsule. Environmental conditions were measured using a Kestrel heat stress tracker. Following completion of a heat-stress protocol, participants underwent one of the four randomized cooling protocols. These cooling protocols consisted of: 1) wearing an ice vest (18°C), 2) applying an icy towel directly to the back of the neck (24°C) in combination with hand/forearm water immersion (15°C), 3) a combination of ice vest, icy towel and hand/forearm water immersion, or 4) sitting in a thermoneutral room (20°C). In all cooling interventions, participants consumed 16oz of an ice slurry (0°C) within 10 minutes of the initiation of the protocol. The control group consumed only room temperature water- ad libitum. A total of 10 active males (25 ± 3 years old) reported no difference between baseline body core temperatures after each heating intervention (P=0.23). Average core temperature and heart rate differed, though not statistically significant between treatments (P>0.05). No significant differences were noted between cooling rates (P=0.51). Skin temperature (Tsk) average and decrement was found to be statistically significant (P<0.001).
ContributorsCaballero, Rachel (Author) / Wardenaar, Floris (Thesis advisor) / Kavouras, Stavros (Committee member) / Vanos, Jennifer (Committee member) / Arizona State University (Publisher)
Created2022
Description
Increasing demands of youth sport participation has resulted in a lack of time for youth to engage in non-sport activities associated with positive youth development (PYD; West & Strand, 2016; Witt & Dangi, 2018). Though sport participation has the potential to increase positive PYD in participants, it is evident that sport participation alone does not generate PYD (Coakley, 2011). A positive environment, space to build internal assets, and continuous intentional, evaluative programs are a few of the components that may facilitate PYD in sport (Petitpas, Cornelius, Van Raalte, & Jones, 2005). When an appropriate development context is lacking, sport participation may actually lead to negative outcomes including intrapersonal (e.g. anxiety due to excessive criticism), interpersonal (e.g. parental pressure or lack of time to participate in other age-appropriate activities), or structural outcomes (e.g. overuse/burnout, cost, or lack of free play) (Witt & Dangi, 2018; Reverdito, et al., 2020). These risks may be particularly pronounced for athletes whose sole activity is sport. One way to address this is to provide non-sport activities as part of a sport program. For example, creative arts activities can enhance self-awareness (Perryman, Moss, & Cochran, 2015), improve communication (Moon, 2007), and decrease psychological distress (Ansari & Lalani, 2014). Further, creative arts can be sport related and built into sport program. Given the value of creative activities in PYD, and the potential lack of creative opportunities for athletes, it is important to examine if such activities are associated with PYD outcomes for athletes. Thus, the purpose of this study was to explore the experience of participation in creative activities for youth athletes, with a specific focus on potential PYD associations. Fifteen current youth sport athletes engaged in an art-based activity, followed by a semi-structured interview. Findings suggest indicators of active engagement in creative art activities are distraction, reflection, expression, and relaxation. Further, when participants were actively engaged in creative arts, they perceived the following three benefits: 1) connection with teammates, 2) empowerment, and 3) positive identity. These findings provide practical implication for youth sport administrators as well as contribute to the limited body of literature on creative arts and youth sport programing.
ContributorsVarney, Rebecca (Author) / Legg, Walter (Thesis advisor) / Wise, Nicholas (Committee member) / Ross, Allison (Committee member) / Arizona State University (Publisher)
Created2021