Matching Items (11)
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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
Concern regarding the quality of traffic data exists among engineers and planners tasked with obtaining and using the data for various transportation applications. While data quality issues are often understood by analysts doing the hands on work, rarely are the quality characteristics of the data effectively communicated beyond the analyst. This research is an exercise in measuring and reporting data quality. The assessment was conducted to support the performance measurement program at the Maricopa Association of Governments in Phoenix, Arizona, and investigates the traffic data from 228 continuous monitoring freeway sensors in the metropolitan region. Results of the assessment provide an example of describing the quality of the traffic data with each of six data quality measures suggested in the literature, which are accuracy, completeness, validity, timeliness, coverage and accessibility. An important contribution is made in the use of data quality visualization tools. These visualization tools are used in evaluating the validity of the traffic data beyond pass/fail criteria commonly used. More significantly, they serve to educate an intuitive sense or understanding of the underlying characteristics of the data considered valid. Recommendations from the experience gained in this assessment include that data quality visualization tools be developed and used in the processing and quality control of traffic data, and that these visualization tools, along with other information on the quality control effort, be stored as metadata with the processed data.
ContributorsSamuelson, Jothan P (Author) / Pendyala, Ram M. (Thesis advisor) / Ahn, Soyoung (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
The United States resettles more refugees each year than any country, yet little is known about the influence that the Refugee Resettlement Program has on our communities. Program evaluation in the United States is primarily concerned with outcomes and efficiency; while there has been an absence of collecting data to measure the impact that social programs have on communities. This study explores the impact of refugee resettlement on a metropolitan area by surveying professionals with experience working or volunteering with refugee populations. These professionals rate the extent to which they believe refugee resettlement influences social, economic, and environmental variables in the community, and explain the nature of the influence they believe the program has on the community. The data collected from these surveys will introduce the perceived impact of refugee resettlement from the perspective of those with professional experience in the area. By exploring the effects that the Refugee Resettlement Program has on Phoenix, this data can assist in the creation of community assessments for refugee resettlement and comparable social programs.
ContributorsMody, Elizabeth Hatch (Author) / Klimek, Barbara (Thesis advisor) / Morales, Joanne (Committee member) / Brown, Mary-Ellen (Committee member) / Arizona State University (Publisher)
Created2018
How Does Technology Development Influence the Assessment of Parkinson’s Disease? A Systematic Review
Description
Parkinson’s disease (PD) is a neurological disorder with complicated and disabling motor and non-motor symptoms. The pathology for PD is difficult and expensive. Furthermore, it depends on patient diaries and the neurologist’s subjective assessment of clinical scales. Objective, accurate, and continuous patient monitoring have become possible with the advancement in mobile and portable equipment. Consequently, a significant amount of work has been done to explore new cost-effective and subjective assessment methods or PD symptoms. For example, smart technologies, such as wearable sensors and optical motion capturing systems, have been used to analyze the symptoms of a PD patient to assess their disease progression and even to detect signs in their nascent stage for early diagnosis of PD.
This review focuses on the use of modern equipment for PD applications that were developed in the last decade. Four significant fields of research were identified: Assistance diagnosis, Prognosis or Monitoring of Symptoms and their Severity, Predicting Response to Treatment, and Assistance to Therapy or Rehabilitation. This study reviews the papers published between January 2008 and December 2018 in the following four databases: Pubmed Central, Science Direct, IEEE Xplore and MDPI. After removing unrelated articles, ones published in languages other than English, duplicate entries and other articles that did not fulfill the selection criteria, 778 papers were manually investigated and included in this review. A general overview of PD applications, devices used and aspects monitored for PD management is provided in this systematic review.
This review focuses on the use of modern equipment for PD applications that were developed in the last decade. Four significant fields of research were identified: Assistance diagnosis, Prognosis or Monitoring of Symptoms and their Severity, Predicting Response to Treatment, and Assistance to Therapy or Rehabilitation. This study reviews the papers published between January 2008 and December 2018 in the following four databases: Pubmed Central, Science Direct, IEEE Xplore and MDPI. After removing unrelated articles, ones published in languages other than English, duplicate entries and other articles that did not fulfill the selection criteria, 778 papers were manually investigated and included in this review. A general overview of PD applications, devices used and aspects monitored for PD management is provided in this systematic review.
ContributorsDeb, Ranadeep (Author) / Ogras, Umit Y. (Thesis advisor) / Shill, Holly (Committee member) / Chakrabarti, Chaitali (Committee member) / Arizona State University (Publisher)
Created2019
Description
ABSTRACT
Psychological assessments contain important diagnostic information and are central to therapeutic service delivery. Therapists' personal biases, invalid cognitive schemas, and emotional reactions can be expressed in the language of the assessments they compose, causing clients to be cast in an unfavorable light. Logically, the opinions of subsequent therapists may then be influenced by reading these assessments, resulting in negative attitudes toward clients, inaccurate diagnoses, adverse experiences for clients, and poor therapeutic outcomes. However, little current research exists that addresses this issue. This study analyzed the degree to which strength-based, deficit-based, and neutral language used in psychological assessments influenced the opinions of counselor trainees (N= 116). It was hypothesized that participants assigned to each type of assessment would describe the client using adjectives that closely conformed to the language used in the assessment they received. The hypothesis was confirmed (p = .000), indicating significant mean differences between all three groups. Limitations and implications of the study were identified and suggestions for further research were discussed.
Psychological assessments contain important diagnostic information and are central to therapeutic service delivery. Therapists' personal biases, invalid cognitive schemas, and emotional reactions can be expressed in the language of the assessments they compose, causing clients to be cast in an unfavorable light. Logically, the opinions of subsequent therapists may then be influenced by reading these assessments, resulting in negative attitudes toward clients, inaccurate diagnoses, adverse experiences for clients, and poor therapeutic outcomes. However, little current research exists that addresses this issue. This study analyzed the degree to which strength-based, deficit-based, and neutral language used in psychological assessments influenced the opinions of counselor trainees (N= 116). It was hypothesized that participants assigned to each type of assessment would describe the client using adjectives that closely conformed to the language used in the assessment they received. The hypothesis was confirmed (p = .000), indicating significant mean differences between all three groups. Limitations and implications of the study were identified and suggestions for further research were discussed.
ContributorsScott, Angela N (Author) / Kinnier, Richard (Thesis advisor) / Homer, Judith (Committee member) / Kurpius, Sharon (Committee member) / Arizona State University (Publisher)
Created2015
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 Rapid Eating and Activity Assessment for Participants Short Version (REAP-S), represents a method for rapid diet quality assessment, however, few studies have tested its validity. The Healthy Eating Index-2005 (HEI-2005) and the Diet Quality Index Revised (DQI-R) are tools that effectively assess diet quality, however, both are complex and time consuming. The objective of this study was to evaluate the validity of the REAP-S against the HEI-2005 and the DQI-R. Fifty males, 18 to 33 years of age, completed the REAP-S as well as a 24-hour diet recall. HEI-2005 and DQI-R scores were determined for each 24-hour recall. Scores from the REAP-S were evaluated against the HEI-2005 and DQI-R scores using Spearman rank order correlations and chi square. Modifications were also made to the original method of scoring the REAP-S to evaluate how the correlations transformed when certain questions were removed. The correlation coefficient for REAP-S and the HEI-2005 was 0.367 (P=0.009), and the correlation coefficient for REAP-S and the DQI-R was 0.323 (P=0.022). Chi square determined precision of the REAP-S to the HEI-2005 for overall diet quality at 64% and 62% for the DQI-R and REAP-S. Scores that were considered extreme (n=21) by the HEI-2005 (scores <40 and >60) had 76% precision with REAP-S. The correlation for the modified version of scoring REAP-S with the overall HEI-2005 and DQI-R were 0.395 (P=0.005) and 0.417 (P=0.003) respectively. Chi square statistics revealed the REAP-S accurately captured the diets of high quality versus low quality with 64% precision to the HEI-2005 and 62% of the DQI-R. When evaluating the modified REAP-S scores against the extreme HEI-2005 scores, precision increased to 81%. It appears the REAP-S is an acceptable tool to rapidly assess diet quality. It has a significant, moderate correlation to both the HEI-2005 and the DQI-R, with strong precision as well. Both correlation and precision is strengthened when values are compared to only the extreme scores of the HEI-2005; however, more research studies are needed to evaluate the validity of REAP-S in a more diverse population and to evaluate if changes to select questions can improve its accuracy in assessing diet quality.
ContributorsFawcett, Rachael (Author) / Johnston, Carol (Thesis advisor) / Mayol-Kreiser, Sandra (Committee member) / Wharton, Christopher (Christopher Mack), 1977- (Committee member) / Arizona State University (Publisher)
Created2012
Description
Currently, there are few quality tools available to screen for developmental language disorder (DLD) in Spanish-speaking children despite the continued increase of this population in the United States. The lack of valid and reliable screening tools may be a factor leading to difficulties with the identification of and delivery of services to these children. This study plans to improve upon the screening of Spanish-English bilingual children.The Spanish Screener for Language Impairment in Children (SSLIC) tests Spanish oral language skills in Spanish-speaking children. It measures language skills through morphology elicitation of Spanish clitics, prepositions, derivational morphemes, subjunctive verb tenses, and articles and repetition of nonwords and sentences, which have all been shown to be affected in Spanish-speaking children with DLD.
The purpose of the study is to provide preliminary validity evidence of the SSLIC. Children's results on the SSLIC were compared to other validated measures. Fourteen Spanish-English bilingual students were recruited: 11 children with typical language development (TD) and 3 with DLD. The Bilingual English-Spanish Assessment and the Dynamic Measure of Oral Narrative Discourse were used to establish preliminary validity evidence. Pearson correlations were run to determine if SSLIC scores correlated with other validated measures. Significant correlations were found between the SSLIC’s scores and scores on the BESA. One-way analysis of variance (ANOVA) was used to determine mean differences between groups. No significant mean differences for SSLIC scores were found between children with typical and atypical language. Yet, effect sizes suggested group differences. Point to point analysis revealed that the SSLIC has excellent inter-rater reliability.
Despite a small sample size, this study serves as preliminary evidence that the SSLIC is both valid and reliable and supports that the SSLIC has the potential to be used as a screening tool for DLD for Spanish-speaking kindergarten and 1st grade students with further validation, which should continue.
ContributorsSmith, Brandon Earl (Author) / Restrepo, María A (Thesis advisor) / Gray, Shelley (Committee member) / Brown, Jean C (Committee member) / Moen, Theresa C (Committee member) / Arizona State University (Publisher)
Created2023
Description
The United States Supreme Court’s 1993 Daubert v. Merrell Dow Pharmaceuticals case established criteria for admitting scientific evidence in federal courts. It holds that scientific evidence must be valid, reliable, and relevant, and judges are required to be “gatekeepers” of evidence by screening out evidence that has not been empirically tested or vetted through the academic community. Yet, little is known about whether psychological assessment tools are subjected to scrutiny through the standards courts are supposed to apply. In three different studies, from the perspectives of judges, attorneys, and forensic mental health experts, the authors investigate whether psychological assessment evidence is being challenged. Information was collected on participants’ experiences with challenges to psychological assessments. Judges and lawyers completed a series of experimental case vignettes to assess their decision-making about legal admissibility of different qualities of psychological assessments. It was hypothesized they would not distinguish between low- and high-quality psychological assessments in admissibility. Bayesian model selection methods did not support the null hypothesis, however. It was found attorneys differentiate between the conditions. The rates in which legal professionals and forensic mental health evaluators experienced challenges were also higher than was expected. These positive findings show there is some degree of gatekeeping psychological assessment evidence in the courts.
ContributorsNeu Line, Emily C (Author) / Neal, Tess M.S. (Thesis advisor) / Horne, Zachary (Committee member) / Saks, Michael (Committee member) / Arizona State University (Publisher)
Created2020