Matching Items (250)
Description
Power spectral analysis is a fundamental aspect of signal processing used in the detection and \\estimation of various signal features. Signals spaced closely in frequency are problematic and lead analysts to miss crucial details surrounding the data. The Capon and Bartlett methods are non-parametric filterbank approaches to power spectrum estimation. The Capon algorithm is known as the "adaptive" approach to power spectrum estimation because its filter impulse responses are adapted to fit the characteristics of the data. The Bartlett method is known as the "conventional" approach to power spectrum estimation (PSE) and has a fixed deterministic filter. Both techniques rely on the Sample Covariance Matrix (SCM). The first objective of this project is to analyze the origins and characteristics of the Capon and Bartlett methods to understand their abilities to resolve signals closely spaced in frequency. Taking into consideration the Capon and Bartlett's reliance on the SCM, there is a novelty in combining these two algorithms using their cross-coherence. The second objective of this project is to analyze the performance of the Capon-Bartlett Cross Spectra. This study will involve Matlab simulations of known test cases and comparisons with approximate theoretical predictions.
ContributorsYoshiyama, Cassidy (Author) / Richmond, Christ (Thesis director) / Bliss, Daniel (Committee member) / Electrical Engineering Program (Contributor, Contributor, Contributor) / Barrett, The Honors College (Contributor)
Created2019-05
Description
Background: Vascular brachytherapy (VBT) is an established treatment for the management of in-stent restenosis (ISR). However, whether VBT is associated with improved patient-reported outcomes is unknown and not been previously studied.
Methods: The authors evaluated 51 consecutive patients, age 18 years and older undergoing VBT in one or more coronary arteries from January 2018 to September 2019. Data on baseline characteristics, procedural outcomes, and occurrence of adverse events were obtained. All patients completed the Seattle Angina Questionnaire – 7 (SAQ-7) form before and after the intervention at 1 month and 6 months.
Results: The mean age was 69 ± 9 years and 29 (57%) of patients were males. Most patients had hypertension (n = 44, 86%) and diabetes (n = 29, 57%). The use of aspirin was 90% while 96% of patients were on P2Y12 inhibitors. 48 (94%) patients were on antianginal therapy. The procedural success was 94.1%. The mean summary SAQ-7 score improved significantly (53.2 ± 21 vs. 83 ± 19, p<0.001) at 30-days. The median Quality of Life (QoL) component of the SAQ-7 score at baseline was 31.3 (Interquartile Range [IQR]: 18.8, 62.5) and improved to 82.5 (IQR: 62.5, 100), p<0.001 at 30 days and 87.5 [IQR: 75, 100), p<0.001 at last follow up. Likewise, the median angina frequency component of the SQL-7 score pre-VBT was 55 (IQR: 45, 80) and improved significantly to 90 (IQR: 60, 100) at 30-days, p<0.001 and 100 [IQR: 68.8, 100], p=0.02 at last follow up. Lastly, the median activity component of the SAQ-7 score improved from 83.3 (IQR: 60 – 100) to 100 (IQR: 83, 100), p = 0.01 at 30-days.
Conclusion: This study demonstrated improvement in patient-reported outcome measures following vascular brachytherapy that are evident as early as 1 month after the intervention and sustained at a median follow up of 17 months.
Methods: The authors evaluated 51 consecutive patients, age 18 years and older undergoing VBT in one or more coronary arteries from January 2018 to September 2019. Data on baseline characteristics, procedural outcomes, and occurrence of adverse events were obtained. All patients completed the Seattle Angina Questionnaire – 7 (SAQ-7) form before and after the intervention at 1 month and 6 months.
Results: The mean age was 69 ± 9 years and 29 (57%) of patients were males. Most patients had hypertension (n = 44, 86%) and diabetes (n = 29, 57%). The use of aspirin was 90% while 96% of patients were on P2Y12 inhibitors. 48 (94%) patients were on antianginal therapy. The procedural success was 94.1%. The mean summary SAQ-7 score improved significantly (53.2 ± 21 vs. 83 ± 19, p<0.001) at 30-days. The median Quality of Life (QoL) component of the SAQ-7 score at baseline was 31.3 (Interquartile Range [IQR]: 18.8, 62.5) and improved to 82.5 (IQR: 62.5, 100), p<0.001 at 30 days and 87.5 [IQR: 75, 100), p<0.001 at last follow up. Likewise, the median angina frequency component of the SQL-7 score pre-VBT was 55 (IQR: 45, 80) and improved significantly to 90 (IQR: 60, 100) at 30-days, p<0.001 and 100 [IQR: 68.8, 100], p=0.02 at last follow up. Lastly, the median activity component of the SAQ-7 score improved from 83.3 (IQR: 60 – 100) to 100 (IQR: 83, 100), p = 0.01 at 30-days.
Conclusion: This study demonstrated improvement in patient-reported outcome measures following vascular brachytherapy that are evident as early as 1 month after the intervention and sustained at a median follow up of 17 months.
ContributorsRawal, Sahil (Author) / Gould, Ian (Thesis director) / Sawant, Abhishek C. (Committee member) / Department of Psychology (Contributor) / Barrett, The Honors College (Contributor)
Created2020-05
Leveraging Machine Learning and Wireless Sensing for Robot Localization - Location Variance Analysis
Description
Object localization is used to determine the location of a device, an important aspect of applications ranging from autonomous driving to augmented reality. Commonly-used localization techniques include global positioning systems (GPS), simultaneous localization and mapping (SLAM), and positional tracking, but all of these methodologies have drawbacks, especially in high traffic indoor or urban environments. Using recent improvements in the field of machine learning, this project proposes a new method of localization using networks with several wireless transceivers and implemented without heavy computational loads or high costs. This project aims to build a proof-of-concept prototype and demonstrate that the proposed technique is feasible and accurate.
Modern communication networks heavily depend upon an estimate of the communication channel, which represents the distortions that a transmitted signal takes as it moves towards a receiver. A channel can become quite complicated due to signal reflections, delays, and other undesirable effects and, as a result, varies significantly with each different location. This localization system seeks to take advantage of this distinctness by feeding channel information into a machine learning algorithm, which will be trained to associate channels with their respective locations. A device in need of localization would then only need to calculate a channel estimate and pose it to this algorithm to obtain its location.
As an additional step, the effect of location noise is investigated in this report. Once the localization system described above demonstrates promising results, the team demonstrates that the system is robust to noise on its location labels. In doing so, the team demonstrates that this system could be implemented in a continued learning environment, in which some user agents report their estimated (noisy) location over a wireless communication network, such that the model can be implemented in an environment without extensive data collection prior to release.
Modern communication networks heavily depend upon an estimate of the communication channel, which represents the distortions that a transmitted signal takes as it moves towards a receiver. A channel can become quite complicated due to signal reflections, delays, and other undesirable effects and, as a result, varies significantly with each different location. This localization system seeks to take advantage of this distinctness by feeding channel information into a machine learning algorithm, which will be trained to associate channels with their respective locations. A device in need of localization would then only need to calculate a channel estimate and pose it to this algorithm to obtain its location.
As an additional step, the effect of location noise is investigated in this report. Once the localization system described above demonstrates promising results, the team demonstrates that the system is robust to noise on its location labels. In doing so, the team demonstrates that this system could be implemented in a continued learning environment, in which some user agents report their estimated (noisy) location over a wireless communication network, such that the model can be implemented in an environment without extensive data collection prior to release.
ContributorsChang, Roger (Co-author) / Kann, Trevor (Co-author) / Alkhateeb, Ahmed (Thesis director) / Bliss, Daniel (Committee member) / Electrical Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2020-05
Description
This thesis outlines the hand-held memory characterization testing system that is to be created into a PCB (printed circuit board). The circuit is designed to apply voltages diagonally through a RRAM cell (32x32 memory array). The purpose of this sweep across the RRAM is to measure and calculate the high and low resistance state value over a specified amount of testing cycles. With each cell having a unique output of high and low resistance states a unique characterization of each RRAM cell is able to be developed. Once the memory is characterized, the specific RRAM cell that was tested is then able to be used in a varying amount of applications for different things based on its uniqueness. Due to an inability to procure a packaged RRAM cell, a Mock-RRAM was instead designed in order to emulate the same behavior found in a RRAM cell.
The final testing circuit and Mock-RRAM are varied and complex but come together to be able to produce a measured value of the high resistance and low resistance state. This is done by the Arduino autonomously digitizing the anode voltage, cathode voltage, and output voltage. A ramp voltage that sweeps from 1V to -1V is applied to the Mock-RRAM acting as an input. This ramp voltage is then later defined as the anode voltage which is just one of the two nodes connected to the Mock-RRAM. The cathode voltage is defined as the other node at which the voltage drops across the Mock-RRAM. Using these three voltages as input to the Arduino, the Mock-RRAM path resistance is able to be calculated at any given point in time. Conducting many test cycles and calculating the high and low resistance values allows for a graph to be developed of the chaotic variation of resistance state values over time. This chaotic variation can then be analyzed further in the future in order to better predict trends and characterize the RRAM cell that was tested.
Furthermore, the interchangeability of many devices on the PCB allows for the testing system to do more in the future. Ports have been added to the final PCB in order to connect a packaged RRAM cell. This will allow for the characterization of a real RRAM memory cell later down the line rather than a Mock-RRAM as emulation. Due to the autonomous testing, very few human intervention is needed which makes this board a great baseline for others in the future looking to add to it and collect larger pools of data.
The final testing circuit and Mock-RRAM are varied and complex but come together to be able to produce a measured value of the high resistance and low resistance state. This is done by the Arduino autonomously digitizing the anode voltage, cathode voltage, and output voltage. A ramp voltage that sweeps from 1V to -1V is applied to the Mock-RRAM acting as an input. This ramp voltage is then later defined as the anode voltage which is just one of the two nodes connected to the Mock-RRAM. The cathode voltage is defined as the other node at which the voltage drops across the Mock-RRAM. Using these three voltages as input to the Arduino, the Mock-RRAM path resistance is able to be calculated at any given point in time. Conducting many test cycles and calculating the high and low resistance values allows for a graph to be developed of the chaotic variation of resistance state values over time. This chaotic variation can then be analyzed further in the future in order to better predict trends and characterize the RRAM cell that was tested.
Furthermore, the interchangeability of many devices on the PCB allows for the testing system to do more in the future. Ports have been added to the final PCB in order to connect a packaged RRAM cell. This will allow for the characterization of a real RRAM memory cell later down the line rather than a Mock-RRAM as emulation. Due to the autonomous testing, very few human intervention is needed which makes this board a great baseline for others in the future looking to add to it and collect larger pools of data.
ContributorsDobrin, Ryan Christopher (Co-author) / Halden, Matthew (Co-author) / Hall, Tanner (Co-author) / Barnaby, Hugh (Thesis director) / Kitchen, Jennifer (Committee member) / Electrical Engineering Program (Contributor, Contributor) / Barrett, The Honors College (Contributor)
Created2019-05
Description
Current technology does not allow for the full amount of power produced by solar arrays (PV) on spacecraft to be utilized. The arrays are designed with non-reconfigurable architectures and sent on fifteen to twenty year long missions. They cannot be changed once they are in space, so the arrays are designed for the end of life. Throughout their lifetime, solar arrays can degrade in power producing capabilities anywhere from 20% to 50%. Because there is such a drastic difference in the beginning and end of life power production, and because they cannot be reconfigured, a new design has been found necessary in order to increase power production. Reconfiguration allows the solar arrays to achieve maximum power producing capabilities at both the beginning and end of their lives. With the potential to increase power production by 50%, the reconfiguration design consists of a switching network to be able to utilize any combination of cells. The design for reconfiguration must meet the power requirements of the solar array. This thesis will explore different designs for reconfiguration, as well as possible switches for implementation. It will also review other methods to increase power production, as well as discuss future work in this field.
ContributorsJohnson, Everett Hope (Author) / Kitchen, Jennifer (Thesis director) / Ozev, Sule (Committee member) / School of International Letters and Cultures (Contributor) / Electrical Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2018-05
Description
The Phoenix CubeSat is a 3U Earth imaging CubeSat which will take infrared (IR) photos of cities in the United Stated to study the Urban Heat Island Effect, (UHI) from low earth orbit (LEO). It has many different components that need to be powered during the life of its mission. The only power source during the mission will be its solar panels. It is difficult to calculate power generation from solar panels by hand because of the different orientations the satellite will be positioned in during orbit; therefore, simulation will be used to produce power generation data. Knowing how much power is generated is integral to balancing the power budget, confirming whether there is enough power for all the components, and knowing whether there will be enough power in the batteries during eclipse. This data will be used to create an optimal design for the Phoenix CubeSat to accomplish its mission.
ContributorsBarakat, Raymond John (Author) / White, Daniel (Thesis director) / Kitchen, Jennifer (Committee member) / Electrical Engineering Program (Contributor, Contributor) / Barrett, The Honors College (Contributor)
Created2017-05
Description
This study seeks to determine whether female and male students in general chemistry courses differ in exam and course-based performance. Using data from previous semesters of CHM 101 (Marks), CHM 101 (Bauer), CHM 114 (Seo, Windman), CHM 113/116 (Cabirac), and CHM 117/118 (Williams) courses taught at Arizona State University, the total exam scores and final course grades for each student were recorded and analyzed. The results of this study differ greatly by course type, as each course corresponded to a different STEM major. While CHM 113/116, the pre-medicinal majors course, saw evidence of stereotype threat via lower female exam performance, the other courses saw no statistical difference between male and female performance on their exam scores or overall course grades. For CHM 101, this was understandable, as the majority of students were nursing majors, who likely did not experience tokenism or feel stereotyped negatively in their science classes. However, CHM 114, the engineering majors course, and CHM 117/118, the research science course, saw parity with respect to male and female student performance. This suggests the possibility that female students face adversity in science and math courses before college that cause only those with high self-efficacy to advance to a career in these fields.
ContributorsWoner, Victoria Elaine (Author) / Gould, Ian (Thesis director) / Saenz, Delia (Committee member) / Austin, Ara (Committee member) / Department of Psychology (Contributor) / School of Molecular Sciences (Contributor) / Barrett, The Honors College (Contributor)
Created2016-12
Description
The main objective of this project is to create a hydrogel based material system to capture and release CCRF-CEM Leukemia cancer cells via chemo-mechanical modulation. This system is composed of an aptamer-functionalized hydrogel thin film at the bottom of a microfluidic channel, which changes its film thickness as the temperature of the fluid in the system changes. The functionalized hydrogel film has been created as the primary steps to creating the microfluidic device that could capture and release leukemia cells by turning the temperature of the fluid and length of exposure. Circulating tumor cells have recently become a highly studied area since they have become associated with the likelihood of patient survival. Further, circulating tumor cells can be used to determine changes in the genome of the cancer leading to targeted treatment. First, the aptamers were attached onto the hydrogel through an EDC/NHS reaction. The aptamers were verified to be attached onto the hydrogel through FTIR spectroscopy. The cell capture experiments were completed by exposing the hydrogel to a solution of leukemia cells for 10 minutes at room temperature. The cell release experiments were completed by exposing the hydrogel to a 40°C solution. Several capture and release experiments were completed to measure how many cells could be captured, how quickly, and how many cells captured were released. The aptamers were chemically attached to the hydrogel. 300 cells per square millimeter could be captured at a time in a 10 minute time period and released in a 5 minute period. Of the cells captured, 96% of them were alive once caught. 99% of cells caught were released once exposed to elevated temperature. The project opens the possibility to quickly and efficiently capture and release tumor cells using only changes in temperature. Further, most of the cells that were captured were alive and nearly all of those were released leading to high survival and capture efficiency.
ContributorsPaxton, Rebecca Joanne (Author) / Stephanopoulos, Nicholas (Thesis director) / He, Ximin (Committee member) / Gould, Ian (Committee member) / Materials Science and Engineering Program (Contributor) / School of Molecular Sciences (Contributor) / Barrett, The Honors College (Contributor)
Created2016-12
Description
Buck converters are a class of switched-mode power converters often used to step down DC input voltages to a lower DC output voltage. These converters naturally produce a current and voltage ripple at their output due to their switching action. Traditional methods of reducing this ripple have involved adding large discrete inductors and capacitors to filter the ripple, but large discrete components cannot be integrated onto chips. As an alternative to using passive filtering components, this project investigates the use of active ripple cancellation to reduce the peak output ripple. Hysteretic controlled buck converters were chosen for their simplicity of design and fast transient response. The proposed cancellation circuits sense the output ripple of the buck converter and inject an equal ripple exactly out of phase with the sensed ripple. Both current-mode and voltage-mode feedback loops are simulated, and the effectiveness of each cancellation circuit is examined. Results show that integrated active ripple cancellation circuits offer a promising substitute for large discrete filters.
ContributorsWang, Ziyan (Author) / Bakkaloglu, Bertan (Thesis director) / Kitchen, Jennifer (Committee member) / Electrical Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2017-12
Description
This paper reviews several current designs of Cube Satellite (CubeSat) Electrical Power Systems (EPS) based on Silicon FET technologies and their current deficiencies, such as radiation-incurred defects and switching power losses. A strategy to fix these is proposed by the way of using Gallium Nitride (GaN) High Electron-Mobility Transistors (HEMTs) as switching devices within Buck/Boost Converters and other regulators. This work summarizes the EPS designs of several CubeSat missions, classifies them, and outlines their efficiency. An in-depth example of an EPS is also given, explaining the process in which these systems are designed. Areas of deficiency are explained along with reasoning as to why GaN can mitigate these losses, including its wide bandgap properties such as high RDS(on) and High Breakdown Voltage. Special design considerations must be kept in mind when using GaN HEMTs in this application and an example of a CubeSat using GaN HEMTs is mentioned. Finally, challenges ahead for GaN are explored including manufacturing considerations and long-term reliability.
ContributorsWilloughby, Alexander George (Author) / Kitchen, Jennifer (Thesis director) / Zhao, Yuji (Committee member) / Electrical Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2017-05