Matching Items (422)
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As the 3rd generation solar cell, quantum dot solar cells are expected to outperform the first 2 generations with higher efficiency and lower manufacture cost. Currently the main problems for QD cells are the low conversion efficiency and stability. This work is trying to improve the reliability as well as

As the 3rd generation solar cell, quantum dot solar cells are expected to outperform the first 2 generations with higher efficiency and lower manufacture cost. Currently the main problems for QD cells are the low conversion efficiency and stability. This work is trying to improve the reliability as well as the device performance by inserting an interlayer between the metal cathode and the active layer. Titanium oxide and a novel nitrogen doped titanium oxide were compared and TiOxNy capped device shown a superior performance and stability to TiOx capped one. A unique light anneal effect on the interfacial layer was discovered first time and proved to be the trigger of the enhancement of both device reliability and efficiency. The efficiency was improved by 300% and the device can retain 73.1% of the efficiency with TiOxNy when normal device completely failed after kept for long time. Photoluminescence indicted an increased charge disassociation rate at TiOxNy interface. External quantum efficiency measurement also inferred a significant performance enhancement in TiOxNy capped device, which resulted in a higher photocurrent. X-ray photoelectron spectrometry was performed to explain the impact of light doping on optical band gap. Atomic force microscopy illustrated the effect of light anneal on quantum dot polymer surface. The particle size is increased and the surface composition is changed after irradiation. The mechanism for performance improvement via a TiOx based interlayer was discussed based on a trap filling model. Then Tunneling AFM was performed to further confirm the reliability of interlayer capped organic photovoltaic devices. As a powerful tool based on SPM technique, tunneling AFM was able to explain the reason for low efficiency in non-capped inverted organic photovoltaic devices. The local injection properties as well as the correspondent topography were compared in organic solar cells with or without TiOx interlayer. The current-voltage characteristics were also tested at a single interested point. A severe short-circuit was discovered in non capped devices and a slight reverse bias leakage current was also revealed in TiOx capped device though tunneling AFM results. The failure reason for low stability in normal devices was also discussed comparing to capped devices.
ContributorsYu, Jialin (Author) / Jabbour, Ghassan E. (Thesis advisor) / Alford, Terry L. (Thesis advisor) / Yu, Hongbin (Committee member) / Arizona State University (Publisher)
Created2011
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Advancements in computer vision and machine learning have added a new dimension to remote sensing applications with the aid of imagery analysis techniques. Applications such as autonomous navigation and terrain classification which make use of image classification techniques are challenging problems and research is still being carried out to find

Advancements in computer vision and machine learning have added a new dimension to remote sensing applications with the aid of imagery analysis techniques. Applications such as autonomous navigation and terrain classification which make use of image classification techniques are challenging problems and research is still being carried out to find better solutions. In this thesis, a novel method is proposed which uses image registration techniques to provide better image classification. This method reduces the error rate of classification by performing image registration of the images with the previously obtained images before performing classification. The motivation behind this is the fact that images that are obtained in the same region which need to be classified will not differ significantly in characteristics. Hence, registration will provide an image that matches closer to the previously obtained image, thus providing better classification. To illustrate that the proposed method works, naïve Bayes and iterative closest point (ICP) algorithms are used for the image classification and registration stages respectively. This implementation was tested extensively in simulation using synthetic images and using a real life data set called the Defense Advanced Research Project Agency (DARPA) Learning Applied to Ground Robots (LAGR) dataset. The results show that the ICP algorithm does help in better classification with Naïve Bayes by reducing the error rate by an average of about 10% in the synthetic data and by about 7% on the actual datasets used.
ContributorsMuralidhar, Ashwini (Author) / Saripalli, Srikanth (Thesis advisor) / Papandreou-Suppappola, Antonia (Committee member) / Turaga, Pavan (Committee member) / Arizona State University (Publisher)
Created2011
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Description
Semiconductor nanowires are featured by their unique one-dimensional structure which makes them promising for small scale electronic and photonic device applications. Among them, III-V material nanowires are particularly outstanding due to their good electronic properties. In bulk, these materials reveal electron mobility much higher than conventional silicon based devices, for

Semiconductor nanowires are featured by their unique one-dimensional structure which makes them promising for small scale electronic and photonic device applications. Among them, III-V material nanowires are particularly outstanding due to their good electronic properties. In bulk, these materials reveal electron mobility much higher than conventional silicon based devices, for example at room temperature, InAs field effect transistor (FET) has electron mobility of 40,000 cm2/Vs more than 10 times of Si FET. This makes such materials promising for high speed nanowire FETs. With small bandgap, such as 0.354 eV for InAs and 1.52 eV for GaAs, it does not need high voltage to turn on such devices which leads to low power consumption devices. Another feature of direct bandgap allows their applications of optoelectronic devices such as avalanche photodiodes. However, there are challenges to face up. Due to their large surface to volume ratio, nanowire devices typically are strongly affected by the surface states. Although nanowires can be grown into single crystal structure, people observe crystal defects along the wires which can significantly affect the performance of devices. In this work, FETs made of two types of III-V nanowire, GaAs and InAs, are demonstrated. These nanowires are grown by catalyst-free MOCVD growth method. Vertically nanowires are transferred onto patterned substrates for coordinate calibration. Then electrodes are defined by e-beam lithography followed by deposition of contact metals. Prior to metal deposition, however, the substrates are dipped in ammonium hydroxide solution to remove native oxide layer formed on nanowire surface. Current vs. source-drain voltage with different gate bias are measured at room temperature. GaAs nanowire FETs show photo response while InAs nanowire FETs do not show that. Surface passivation is performed on GaAs FETs by using ammonium surfide solution. The best results on current increase is observed with around 20-30 minutes chemical treatment time. Gate response measurements are performed at room temperature, from which field effect mobility as high as 1490 cm2/Vs is extracted for InAs FETs. One major contributor for this is stacking faults defect existing along nanowires. For InAs FETs, thermal excitations observed from temperature dependent results which leads us to investigate potential barriers.
ContributorsLiang, Hanshuang (Author) / Yu, Hongbin (Thesis advisor) / Ferry, David (Committee member) / Tracy, Clarence (Committee member) / Arizona State University (Publisher)
Created2011
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A workload-aware low-power neuromorphic controller for dynamic power and thermal management in VLSI systems is presented. The neuromorphic controller predicts future workload and temperature values based on the past values and CPU performance counters and preemptively regulates supply voltage and frequency. System-level measurements from stateof-the-art commercial microprocessors are used to

A workload-aware low-power neuromorphic controller for dynamic power and thermal management in VLSI systems is presented. The neuromorphic controller predicts future workload and temperature values based on the past values and CPU performance counters and preemptively regulates supply voltage and frequency. System-level measurements from stateof-the-art commercial microprocessors are used to get workload, temperature and CPU performance counter values. The controller is designed and simulated using circuit-design and synthesis tools. At device-level, on-chip planar inductors suffer from low inductance occupying large chip area. On-chip inductors with integrated magnetic materials are designed, simulated and fabricated to explore performance-efficiency trade offs and explore potential applications such as resonant clocking and on-chip voltage regulation. A system level study is conducted to evaluate the effect of on-chip voltage regulator employing magnetic inductors as the output filter. It is concluded that neuromorphic power controller is beneficial for fine-grained per-core power management in conjunction with on-chip voltage regulators utilizing scaled magnetic inductors.
ContributorsSinha, Saurabh (Author) / Cao, Yu (Thesis advisor) / Bakkaloglu, Bertan (Committee member) / Yu, Hongbin (Committee member) / Christen, Jennifer B. (Committee member) / Arizona State University (Publisher)
Created2011
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Description

Within the last decade, it has become increasingly apparent that the effects of climate change are getting harder and harder to ignore. This fact has led to increased interest in sustainability and an increased pressure from consumers to have these ideals implemented into a variety of global industries. The fashion

Within the last decade, it has become increasingly apparent that the effects of climate change are getting harder and harder to ignore. This fact has led to increased interest in sustainability and an increased pressure from consumers to have these ideals implemented into a variety of global industries. The fashion industry, in particular, has been facing this pressure toward the desire for sustainable products is the fashion industry. Over the last five years, sustainability has become a main focus within the fashion industry. Countless brands now include sustainability within their marketing tactics and a variety of fashion organizations release reports on the unsustainable practices that currently dominate fashion production. These misleading marketing tactics and enigmatic intensive reports lead to confusion on what sustainable fashion actually looks like for both consumers and suppliers alike.<br/> This report attempts to help tackle this problem by using sustainable fashion certifications as a tactic to prove sustainability within business procedures. To compare eight of the most common fashion certifications, this paper assumes a systems thinking approach to creating an assessment framework, which is then applied to said certifications. To back up the importance of the topic, this paper presents key points of the current issues related to this case, which then contribute to the integration of basic sustainability assessment criteria and case-specific factors into overarching core criteria. The application of this framework is utilized to determine which certifications cover certain aspects of the curated core criteria. This is then used to present consumers and manufacturers with a more accurate understanding of each of these certifications. This information is then followed up with a recommendation of certifications that align most within researched-based consumer and supplier desires.

ContributorsReid, Christopher Patrick (Author) / Sewell, Dennita (Thesis director) / Kosak, Jessica (Committee member) / Department of Management and Entrepreneurship (Contributor, Contributor) / School of Art (Contributor) / Barrett, The Honors College (Contributor)
Created2021-05
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The aim of this creative project was to explore the ideas of impermanence and transience through the lens of different, largely non-western cultural backgrounds, and to incorporate what I learned into my own work as a painter. As part of this, I focused on the materials, techniques, visual strategies, and

The aim of this creative project was to explore the ideas of impermanence and transience through the lens of different, largely non-western cultural backgrounds, and to incorporate what I learned into my own work as a painter. As part of this, I focused on the materials, techniques, visual strategies, and philosophies that guided the creation of these works. The project consisted of a discrete research phase, during which time I gathered information and materials related to my topic, and a creation phase, when I focused largely on the production of oil paintings and ink paintings whose technique and/or subject matter pertained to impermanence. Research for the most part was conducted by utilizing online and physical collections of work to analyze the formal elements of the work along with the cultural context in which it was created. Ultimately the creative project resulted in a product of three oil paintings and five ink paintings.

ContributorsLewis, Evan G (Author) / Button, Melissa (Thesis director) / Schoebel, Henry (Committee member) / School of Art (Contributor) / School of Life Sciences (Contributor) / Barrett, The Honors College (Contributor)
Created2021-05
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The purpose of this study is to examine the social and communicative barriers LGBTQIA+ students face when seeking healthcare at campus health and counseling services at Arizona State University. Social barriers relate to experiences and internalizations of societal stigma experienced by sexual and gender minority individuals as well as the

The purpose of this study is to examine the social and communicative barriers LGBTQIA+ students face when seeking healthcare at campus health and counseling services at Arizona State University. Social barriers relate to experiences and internalizations of societal stigma experienced by sexual and gender minority individuals as well as the anticipation of such events. Communication between patient and provider was assessed as a potential barrier with respect to perceived provider LGBTQIA+ competency. This study applies the minority stress model, considering experiences of everyday stigma and minority stress as a predictor of healthcare utilization among sexual and gender minority students. The findings suggest a small but substantial correlation between minority stress and healthcare use with 23.7% of respondents delaying or not receiving one or more types of care due to fear of stigma or discrimination. Additionally, communication findings indicate a lack of standardization of LGBTQIA+ competent care with experiences varying greatly between respondents.

ContributorsZahn, Jennica (Author) / Davis, Olga (Thesis director) / LeMaster, Benny (Committee member) / Watts College of Public Service & Community Solut (Contributor) / School of Art (Contributor) / Barrett, The Honors College (Contributor)
Created2021-05
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Though about 75 percent of American waste is recyclable, only 30 percent of it is actually recycled and less than ten percent of plastics disposed of in the United States in 2015 were recycled. A statistic like this demonstrates the immense need to increase recycling rates in order to move

Though about 75 percent of American waste is recyclable, only 30 percent of it is actually recycled and less than ten percent of plastics disposed of in the United States in 2015 were recycled. A statistic like this demonstrates the immense need to increase recycling rates in order to move towards cultivating a circular economy and benefiting the environment. With Arizona State University’s (ASU) extensive population of on-campus students and faculty, our team was determined to create a solution that would increase recycling rates. After conducting initial market research, our team incentives or education. We conducted market research through student surveys to determine the level of knowledge of our target audience and barriers to entry for local recycling and composting resources. Further, we gained insight into the medium of recycling and sustainability programs they would be interested in participating in. Overall, the results of our surveys demonstrated that a majority of students were interested in participating in these programs, if they were not already involved, and most students on-campus already had access to these resources. Despite having access to these sustainable practices, we identified a knowledge gap between students and their information on how to properly execute sustainable practices such as composting and recycling. In order to address this audience, our team created Circulearning, an educational program that aims to bridge the gap of knowledge and address immediate concerns regarding circular economy topics. By engaging audiences through our quick, accessible educational modules and teaching them about circular practices, we aim to inspire everyone to implement these practices into their own lives. Though our team began the initiative with a focus on implementing these practices solely to ASU campus, we decided to expand our target audience to implement educational programs at all levels after discovering the interest and need for this resource in our community. Our team is extremely excited that our Circulearning educational modules have been shared with a broad audience including students at Mesa Skyline High School, ASU students, and additional connections outside of ASU. With Circulearning, we will educate and inspire people of all ages to live more sustainably and better the environment in which we live.

ContributorsChakravarti, Renuka (Co-author) / Tam, Monet (Co-author) / Carr-Taylor, Kathleen (Co-author) / Byrne, Jared (Thesis director) / Marseille, Alicia (Committee member) / Jordan, Amanda (Committee member) / School of Art (Contributor) / Department of Finance (Contributor) / Barrett, The Honors College (Contributor)
Created2021-05
Description

The market for searching for food online is exploding. According to one expert at Google, “there are over 1 billion restaurant searches on Google every month” (Kelso, 2020). To capture this market and ride the general digital trend of internet personalization (as evidenced by Google search results, ads, YouTube and

The market for searching for food online is exploding. According to one expert at Google, “there are over 1 billion restaurant searches on Google every month” (Kelso, 2020). To capture this market and ride the general digital trend of internet personalization (as evidenced by Google search results, ads, YouTube and social media algorithms, etc), we created Munch to be an algorithm meant to help people find food they’ll love. <br/>Munch offers the ability to search for food by the restaurant or even as specific as a menu item (ex: search for the best Pad Thai). The best part? It is customized to your preferences based on a quiz you take when you open the app and from that point continuously learns from your behavior. This thesis documents the journey of the team who founded Munch, what progress we made and the reasoning behind our decisions, where this idea fits in a competitive marketplace, how much it could be worth, branding, and our recommendations for a successful app in the future.

ContributorsRajan, Megha (Co-author) / Krug, Hayden (Co-author) / Inocencio, Phillippe (Co-author) / Byrne, Jared (Thesis director) / Sebold, Brent (Committee member) / School of Art (Contributor) / Department of Supply Chain Management (Contributor) / Department of Marketing (Contributor) / Barrett, The Honors College (Contributor)
Created2021-05
Description

A collection of storyboards for a graphic novel adaptation of Edgar Allan Poe's "The Oval Portrait." These are drawn in a horror comic style and explore the gothic themes present in "The Oval Portrait" in a visual manner.

ContributorsRea, Sara Mateo (Author) / Fette, Donald (Thesis director) / Davis, Turner (Committee member) / School of Art (Contributor) / Barrett, The Honors College (Contributor)
Created2021-05