Matching Items (14)
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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
In contemporary society, educators teach adolescent students about the importance of developmental growth. This growth transitions into leadership, which prepares youth to collaborate with adults in a working environment. Additionally, youth mural programs generate leadership skills, yet not many art educators are using mural projects as a means to develop leadership in their students. This study explored the connection between working collaboratively on a mural project and the impact it had on leadership traits and skills in adolescent girls. I created an action research project in conjunction with Girl Scouts to encourage a group of girls while creating a mural. The mural project took place at an Arizona Girl Scout resident camp for a total of 11 days. Seven participants between the ages of 14-17 engaged in planning and executing a tile mosaic mural. The image they created remains as a permanent mural for the camp. Qualitative data includes responses to reflection questions and observations. Quantitative data consist of self-reported questionnaire scores before and after the mural project. The data is analyzed to understand if there was a difference in leadership traits and skills before and after instruction. Data is also used to see which leadership traits and/ or skills, if any, were impacted. Findings in the study reveal differences in leadership skills before and after instruction. However, there was not a significant impact to leadership traits. Specific skills that improved include those that involve communication and working with others. I conclude that adolescent girls became more aware of communicating effectively, adapting ideas to others, and working with others after they finished the mural. Additionally participants were more open to sharing thoughts near the end of the project than at the start.
ContributorsMarcinko, Aimee (Author) / Erickson, Mary (Thesis advisor) / Stokrocki, Mary (Committee member) / Young, Bernard (Committee member) / Arizona State University (Publisher)
Created2014
Description
Human resources have always been the most critical factor in the construction industry, and now, with a historic generation entering the age of retirement, the construction industry needs to place greater effort in preparing for the succession of their most important of human resource, their leaders. A significant body of research has shown that succession planning minimizes the negative effects that come with leadership transition; however, little research has focused specifically on the construction industry. The majority of construction companies are family owned or have small pools of potential successors, which make them more susceptible to the negative impacts that occur with poor planning for succession. The objective of this research focuses on developing a methodology that will assist construction companies plan and prepare for a leadership transition. Data is gathered from case studies of twelve construction companies that have recently experienced leadership succession. The data is analyzed for practices and characteristics that correlate to successful leadership transitions. Through the findings in the literature review and data analysis of the case studies, the research successfully achieves the objective of developing a potential methodology for increasing the effectiveness of succession planning in a construction company.
ContributorsPerrenoud, Anthony (Author) / Sullivan, Kenneth T. (Thesis advisor) / Badger, William (Committee member) / Schleifer, Thomas (Committee member) / Arizona State University (Publisher)
Created2012
Description
Current information on successful leadership and management practices is contradictory and inconsistent, which makes difficult to understand what successful business practices are and what are not. The purpose of this study is to identify a simple process that quickly and logically identifies consistent and inconsistent leadership and management criteria. The hypothesis proposed is that Information Measurement Theory (IMT) along with the Kashiwagi Solution Model (KSM) is a methodology than can differentiate between accurate and inaccurate principles the initial part of the study about authors in these areas show how information is conflictive, and also served to establish an initial baseline of recommended practices aligned with IMT. The one author that excels in comparison to the rest suits the "Initial Baseline Matrix from Deming" which composes the first model. The second model is denominated the "Full Extended KSM-Matrix" composed of all the LS characteristics found among all authors and IMT. Both models were tested-out for accuracy. The second part of the study was directed to evaluate the perception of individuals on these principles. Two different groups were evaluated, one group of people that had prior training and knowledge of IMT; another group of people without any knowledge of IMT. The results of the survey showed more confusion in the group of people without knowledge to IMT and improved consistency and less variation in the group of people with knowledge in IMT. The third part of the study, the analysis of case studies of success and failure, identified principles as contributors, and categorized them into LS/type "A" characteristics and RS/type "C" characteristics, by applying the KSM. The results validated the initial proposal and led to the conclusion that practices that fall into the LS side of the KSM will lead to success, while practices that fall into the RS of the KSM will lead to failure. The comparison and testing of both models indicated a dominant support of the IMT concepts as contributors to success; while the KSM model has a higher accuracy of prediction.
ContributorsReynolds, Harry (Author) / Kashiwagi, Dean (Thesis advisor) / Sullivan, Kenneth (Committee member) / Badger, William (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 Hopi people have the distinct term mongwi applied to a person who is charged with leadership of a group. According to Hopi oral history and some contemporary Hopi thought, a mongwi (leader) or group of momngwit (leaders), gain their foremost positions in Hopi society after being recognizably able to fulfill numerous qualifications linked to their respective clan identity, ceremonial initiation, and personal conduct. Numerous occurrences related to the Hopis historical experiences have rendered a substantial record of what are considered the qualifications of a Hopi leader. This thesis is an extensive examination of the language used and the context wherein Hopi people express leadership qualities in the written and documentary record.
ContributorsKaye, Cliff E (Author) / Romero-Little, Eunice (Thesis advisor) / Riding In, James (Committee member) / Tippeconnic III, John (Committee member) / Arizona State University (Publisher)
Created2016
Description
The U.S. Army Medical Command has been testing a leadership based structure to increase the performance of delivering construction and facility services in its system of $600M of construction and 26 major hospital facilities in the U.S. The organizational requirement was to minimize the management and oversight of contractors and simultaneously increase project performance. The research proposes that a leadership based structure can supplement the perception, preplanning, and risk minimization capability of a contractor's project manager, thus increasing the project performance (on time, within budget, and meeting expectations) and decreasing client management requirement. The projects were delivered in a best value and low price environment. The major impact of this research was that proactive management by contractors was more effective than traditional management such as direction, control, and inspection by client's professional representatives. The results based on data collection and date analyses validated that a leadership based structure can increase the performance of an organization and reduce its management requirement.
ContributorsMalhotra, Neha (Author) / Kashiwagi, Dean T. (Thesis advisor) / Sullivan, Kenneth (Committee member) / Badger, William (Committee member) / Arizona State University (Publisher)
Created2010
Description
Dubai has emerged as an important center for international business attracting significant inflows of the foreign workforce. Dubai’s population is unique as nationals represent only 15% of the total population, with 200 other nationalities comprising the other 85%. Thus, Cultural Diversity is unavoidable. Cultural Diversity refers to cultural heterogeneity such as differences in race, ethnicity, language, nationality, and religion. As it is a characteristic of Culturally Heterogeneous Workgroups (CHWs), cultural diversity affects how they interact with each other. Since the core concepts of leadership are dealing, inspiring, and motivating teams, the team member’s diversity directly connects with the leadership concept.While many researchers argue whether (CHWs) suffer or benefit from cultural diversity, it is agreed that such diversity has its challenges. Diverse workgroups have been shown to suffer from poor cohesion and social integration. People who are different from their co-worker’s report feeling uneasy and having less organizational commitment. Miscommunication, the development of obstacles, and improper adaptation behaviors are all possible negative impacts.
In the absence of local studies on how cultural diversity is related to leadership, this thesis questioned the connection between cultural diversity and leadership level through a quantitative research approach. This would help understand how different leaders at different levels perceive cultural diversity challenges, which would help focus on specific level(s) in future and research practical ways to address cultural diversity issues of cultural diversity. Measurement scales for leadership levels and cultural diversity challenges were developed. A survey was used to collect data from skilled workers in the construction industry in Dubai, and non-parametric statistical methods were used to analyze the collected data and answer the research question. Whereas a strong correlation was initially expected between work experience, whether in total or within UAE, and leadership level, this was not the case. Most importantly, no significant evidence was found to support a relationship between cultural diversity challenges and both participants’ leadership level and their UAE work experience.
ContributorsSalama, Anas (Author) / Ariaratnam, Samuel (Thesis advisor) / El Asmar, Mounir (Committee member) / Czerniawski, Thomas (Committee member) / Arizona State University (Publisher)
Created2022