Matching Items (224)
Description
Electrospun nanofibers can be prepared from various kinds of inorganic substances by electro-spinning techniques. They have great potential in many applications including super capacitors, lithium ion batteries, filtration, catalyst and enzyme carriers, and sensors [1]. The traditional way to produce electrospun nanofibers is needle based electro-spinning [1]. However, electrospun nanofibers have not been widely used in practice because of low nanofiber production rates. One way to largely increase the electro-spinning productivity is needleless electro-spinning. In 2005, Jirsak et al. patented a rotating roller fiber generator for the mass production of nanofibers [2]. Elmarco Corporation commercialized this technique to manufacture nanofiber equipment for the production of all sorts of organic and inorganic nanofibers, and named it "NanospiderTM". For this project, my goal is to build a needleless electro-spinner to produce nanofibers as the separator of lithium ion batteries. The model of this project is based on the design of rotating roller fiber generator, and is adapted from a project at North Dakota State University in 2011 [3].
ContributorsQiao, Guanhao (Author) / Yu, Hongyu (Thesis director) / Jiang, Hanqing (Committee member) / Goryll, Michael (Committee member) / Barrett, The Honors College (Contributor) / Ira A. Fulton School of Engineering (Contributor)
Created2012-12
Description
Head's up displays (HUD) are now emerging into the technological market that is used in various functionalities, but most of all, they are expensive. An alternative method to find cheaper ways to develop a head's up display is researched and implemented. The HUD is equipped with a processor and projector. Both of these hardware components encompasses most part of the HUD along with some manipulation of the material that the image is projected on. In this study, the software and the optics of the HUD will be explored and lastly, taking into full consideration on the future work that can be done to make improvements on the HUD.
ContributorsKim, Lilian SA (Author) / Goryll, Michael (Thesis director) / Zhang, Yong-Hang (Committee member) / Barrett, The Honors College (Contributor) / Electrical Engineering Program (Contributor)
Created2014-05
Description
Abstract As we move forward in education reform in the globalized 21st century, the United States must visit new ways to teach science in high school classrooms. The goal of this investigation is to analyze the current research literature for the best and most promising teaching strategies and techniques in secondary education biology classrooms that promote academic excellence for all students. Looking at policy and school reform literature in science education to establish the context of the current system, the paper will not focus on the political as or systematic changes needed to ground an overall successful system. However, because of their inherent effect on the education system, the political aspects of education reform will be briefly addressed. The primary focus, by addressing the emphasis on standardization, inflexibility of instruction and lack of creativity specifically in high school biology classrooms, seeks to clarify small changes that can influence students' academic outcomes. The United States is performing on such a poor level in science and math proficiency that it cannot match students abroad and this is seen through test scores and the production of competent graduates. This investigation serves to organize literature from education researchers and showcase best and promising teaching and learning practices that catalyze academic excellence for all students in our pluralistic, democratic and complex schooling and societal contexts.
ContributorsHildebrandt, Kevin Andrew (Author) / Ovando, Carlos (Thesis director) / Schugurensky, Daniel, 1958- (Committee member) / Fischman, Gustavo (Committee member) / Barrett, The Honors College (Contributor) / School of Life Sciences (Contributor) / School of International Letters and Cultures (Contributor)
Created2013-05
Description
The Metal Semiconductor Field Effect Transistor (MESFET) has high potential to enter analog and RF applications due to their high breakdown voltage and switching frequency characteristics. These MESFET devices could allow for high voltage analog circuits to be integrated with low voltage digital circuits on a single chip in an extremely cost effective way. Higher integration leads to electronics with increased functionality and a smaller finished product. The MESFETs are designed in-house by the research group led by Dr. Trevor Thornton. The layouts are then sent to multi-project wafer (MPW) integrated circuit foundry companies, such as the Metal Oxide Semiconductor Implementation Service (MOSIS) to be fabricated. Once returned, the electrical characteristics of the devices are measured. The MESFET has been implemented in various applications by the research group, including the low dropout linear regulator (LDO) and RF power amplifier. An advantage of the MESFET is that it can function in extreme environments such as space, allowing for complex electrical systems to continue functioning properly where traditional transistors would fail.
ContributorsKam, Jason (Author) / Thornton, Trevor (Thesis director) / Goryll, Michael (Committee member) / Barrett, The Honors College (Contributor) / Electrical Engineering Program (Contributor)
Created2015-05
Description
This study examined the quality of professional life at a Title I school that has achieved the Arizona Department of Education's highest accountability rating of Excelling for eight consecutive years. By examining the factors that influence the school environment including teachers' attitudes and the connections within the teacher community at this school, a description emerged of the factors that influenced the quality of professional lives of teachers. This descriptive study sought to describe, "What is the quality of professional life for teachers at a Title I elementary school with a history of high levels of student achievement?" The research was conducted at Seneca Elementary school (a pseudonym) in the Seneca School District (a pseudonym). By examining the quality of professional life for teachers in a highly ranked Title I school, a better understanding of the quality of professional life may lead to recommendations for other schools with high levels of poverty on how to support teachers who work in high poverty schools. Within a theoretical framework of motivation-hygiene theory and socio cultural theory, the study identified principal leadership as a primary supporting factor of quality of professional life. The study also identified lack of input and lack of teacher control over curriculum and instruction as barriers to quality of professional life. Teachers described principal leadership, environment, social factors and teacher identity as contributors to enhancing the quality of professional life. Trust and focus emerged as additional factors that improved the workplace for teachers.
ContributorsThomas, Jeffrey J (Author) / Danzig, Arnold (Thesis advisor) / Fischman, Gustavo (Committee member) / Boyle, Charlotte (Committee member) / Arizona State University (Publisher)
Created2011
Description
Electronic devices are gaining an increasing market share in the medical field. Medical devices are becoming more sophisticated, and encompassing more applications. Unlike consumer electronics, medical devices have far more limitations when it comes to area, power and most importantly reliability. The medical devices industry has recently seen the advantages of using Flash memory instead of Read Only Memory (ROM) for firmware storage, and in some cases to replace Electrically Programmable Read Only Memories (EEPROMs) in medical devices for frequent data storage. There are direct advantages to using Flash memory instead of Read Only Memory, most importantly the fact that firmware can be rewritten along the development cycle and in the field. However, Flash technology requires high voltage circuitry that makes it harder to integrate into low power devices. There have been a lot of advances in Non-Volatile Memory (NVM) technologies, and many Flash rivals are starting to gain attention. The purpose of this thesis is to evaluate these new technologies against Flash to determine the feasibility as well as the advantages of each technology. The focus is on embedded memory in a medical device micro-controller and application specific integrated circuits (ASIC). A behavioral model of a Programmable Metallization Cell (PMC) was used to simulate the behavior and determine the advantages of using PMC technology versus flash. When compared to flash test data, PMC based embedded memory showed a reduction in power consumption by many orders of magnitude. Analysis showed that an approximated 20% device longevity increase can be achieved by using embedded PMC technology.
ContributorsHag, Eslam E (Author) / Kozicki, Michael N (Thesis advisor) / Schroder, Dieter K. (Committee member) / Goryll, Michael (Committee member) / Arizona State University (Publisher)
Created2010
Description
The constant scaling of supply voltages in state-of-the-art CMOS processes has led to severe limitations for many analog circuit applications. Some CMOS processes have addressed this issue by adding high voltage MOSFETs to their process. Although it can be a completely viable solution, it usually requires a changing of the process flow or adding additional steps, which in turn, leads to an increase in fabrication costs. Si-MESFETs (silicon-metal-semiconductor-field-effect-transistors) from Arizona State University (ASU) on the other hand, have an inherent high voltage capability and can be added to any silicon-on-insulator (SOI) or silicon-on-sapphire (SOS) CMOS process free of cost. This has been proved at five different commercial foundries on technologies ranging from 0.5 to 0.15 μm. Another critical issue facing CMOS processes on insulated substrates is the scaling of the thin silicon channel. Consequently, the future direction of SOI/SOS CMOS transistors may trend away from partially depleted (PD) transistors and towards fully depleted (FD) devices. FD-CMOS are already being implemented in multiple applications due to their very low power capability. Since the FD-CMOS market only figures to grow, it is appropriate that MESFETs also be developed for these processes. The beginning of this thesis will focus on the device aspects of both PD and FD-MESFETs including their layout structure, DC and RF characteristics, and breakdown voltage. The second half will then shift the focus towards implementing both types of MESFETs in an analog circuit application. Aside from their high breakdown ability, MESFETs also feature depletion mode operation, easy to adjust but well controlled threshold voltages, and fT's up to 45 GHz. Those unique characteristics can allow certain designs that were previously difficult to implement or prohibitively expensive using conventional technologies to now be achieved. One such application which benefits is low dropout regulators (LDO). By utilizing an n-channel MESFET as the pass transistor, a LDO featuring very low dropout voltage, fast transient response, and stable operation can be achieved without an external capacitance. With the focus of this thesis being MESFET based LDOs, the device discussion will be mostly tailored towards optimally designing MESFETs for this particular application.
ContributorsLepkowski, William (Author) / Thornton, Trevor (Thesis advisor) / Bakkaloglu, Bertan (Committee member) / Goryll, Michael (Committee member) / Ayyanar, Raja (Committee member) / Arizona State University (Publisher)
Created2010
Description
Silicon Carbide (SiC) junction field effect transistors (JFETs) are ideal for switching high current, high voltage loads in high temperature environments. These devices require external drive circuits to generate pulse width modulated (PWM) signals switching from 0V to approximately 10V. Advanced CMOS microcontrollers are ideal for generating the PWM signals but are limited in output voltage due to their low breakdown voltage within the CMOS drive circuits. As a result, an intermediate buffer stage is required between the CMOS circuitry and the JFET. In this thesis, a discrete silicon-on-insulator (SOI) metal semiconductor field effect transistor (MESFET) was used to drive the gate of a SiC power JFET switching a 120V RMS AC supply into a 30Ω load. The wide operating temperature range and high breakdown voltage of up to 50V make the SOI MESFET ideal for power electronics in extreme environments. Characteristic curves for the MESFET were measured up to 250°C.; To drive the JFET, the MESFET was DC biased and then driven by a 1.2V square wave PWM signal to switch the JFET gate from 0 to 10V at frequencies up to 20kHz. For simplicity, the 1.2V PWM square wave signal was provided by a 555 timer. The JFET gate drive circuit was measured at high temperatures up to 235°C.; The circuit operated well at the high temperatures without any damage to the SOI MESFET or SiC JFET. The drive current of the JFET was limited by the duty cycle range of the 555 timer used. The SiC JFET drain current decreased with increased temperature. Due to the easy integration of MESFETs into SOI CMOS processes, MESFETs can be fabricated alongside MOSFETs without any changes in the process flow. This thesis demonstrates the feasibility of integrating a MESFET with CMOS PWM circuitry for a completely integrated SiC driver thus eliminating the need for the intermediate buffer stage.
ContributorsSummers, Nicholas, M.S (Author) / Thornton, Trevor J (Thesis advisor) / Goryll, Michael (Committee member) / Schroder, Dieter (Committee member) / Arizona State University (Publisher)
Created2010
Description
There is a demonstrable issue in how new medical technologies are developed. The consumer market is always overflowing with the newest possible technologies; however, this is often not the case in the medical field. The consumer market refers to a product that any individual can buy in a retail store, whereas a product for the medical field is prescribed by a clinician for use by a patient. The development of devices usually targets the consumer market rather than the medical field. This trend leads to the development of devices that may have consumer and clinical benefits not receiving consideration in the clinical market because they are not designed with a strictly medical purpose in mind. This is an issue that needs rectification, as injured patients deserve the best possible care with the best technologies available. The development of these technologies should not be limited by a lack of communication between clinicians and engineers. This thesis will explore why product development in the medical field lags behind that of the consumer market. It will also offer practical solutions, as well as having an engineering team develop a device specifically for use in the medical field. The development of this product will show that the lack of communication between clinicians and engineers is possible to overcome. From this development process, recommendations will be made to offer specific solutions to overcome the communication barrier and aid future product development.
ContributorsMagnotto, Samuel Andrew (Author) / Kozicki, Michael (Thesis director) / Goryll, Michael (Committee member) / Electrical Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2020-05
Description
Participatory Budgeting (PB) can create changes within individuals and between them and their community. PB processes allow people to determine how to spend a portion of a particular budget (in the case of School PB, a portion of the school budget). These processes help address the underrepresentation of youth in the realm of civics.
I spent time with the steering committee and teacher coordinator of school PB in Carson Junior High to explore the impact of school PB on students’ knowledge, skills, attitudes and practices in relation to civic engagement. In the study I used quantitative and qualitative components. The participants were unique in that they all had prior experience in civic engagement programs in Carson Junior High that were organized by the teacher coordinator of school PB.
The main findings suggest that the participants reported a significant amount of learning in civic knowledge. In comparison, their overall perceived growth in attitudes, practices and skills were much lower. School PB helped the participants in the steering committee to grow in different ways than their other civic engagement programs by providing them with knowledge about budgets, their school’s mechanisms and other students within their school. They also became more familiar with the democratic process of voting and more comfortable with public speaking and presenting.
Recommendations for future research on this process include compiling quantitative and qualitative data from a larger sample consisting of students who had prior civic engagement experience and students who didn’t, and students with different ethnicities from different grades. Another recommendation for future research is to conduct a longitudinal study following school PB participants to high school and beyond to explore long-term impacts.
ContributorsKinzle, Lauren (Author) / Schugurensky, Daniel, 1958- (Thesis director) / Fischman, Gustavo (Committee member) / Barrett, The Honors College (Contributor) / Dean, W.P. Carey School of Business (Contributor)
Created2019-05