Matching Items (252)
Filtering by
- All Subjects: Communication
- Creators: Arizona State University
Description
Voltage Source Converters (VSCs) have been widely used in grid-connected applications with Distributed Energy Resource (DER) and Electric Vehicle (EV) applications. Replacement of traditional thyristors with Silicon/Silicon-Carbide based active switches provides full control capability to the converters and allows bidirectional power flow between the source and active loads. In this study, advanced control strategies for DER inverters and EV traction inverters will be explored.Chapter 1 gives a brief introduction to State-of-the-Art of VSC control strategies and summarizes the existing challenges in different applications. Chapter 2 presents multiple advanced control strategies of grid-connected DER inverters. Various grid support functions have been implemented in simulations and hardware experiments under both normal and abnormal operating conditions. Chapter 3 proposes an automated design and optimization process of a robust H-infinity controller to address the stability issue of grid-connected inverters caused by grid impedance variation. The principle of the controller synthesis is to select appropriate weighting functions to shape the systems closed-loop transfer function and to achieve robust stability and robust performance. An optimal controller will be selected by using a 2-Dimensional Pareto Front. Chapter 4 proposes a high-performance 4-layer communication architecture to facilitate the control of a large distribution network with high Photovoltaic (PV) penetration. Multiple strategies have been implemented to address the challenges
of coordination between communication and system control and between different communication protocols, which leads to a boost in the communication efficiency and makes the architecture highly scalable, adaptive, and robust. Chapter 5 presents the control strategies of a traditional Modular Multilevel Converter (MMC) and a novel Modular Isolated Multilevel Converter (MIMC) in grid-connected and variable speed drive applications. The proposed MIMC is able to achieve great size reduction for the submodule capacitors since the fundamental and double-line frequency voltage ripple has been cancelled. Chapter 6 shows a detailed hardware and controller design for a 48 V Belt-driven Starter Generator (BSG) inverter using automotive gate driver ICs and microcontroller. The inverter prototype has reached a power density of 333
W/inch3, up to 200 A phase current and 600 Hz output frequency.
ContributorsSi, Yunpeng (Author) / Lei, Qin (Thesis advisor) / Ayyanar, Raja (Committee member) / Vittal, Vijay (Committee member) / Zhang, Junshan (Committee member) / Arizona State University (Publisher)
Created2022
Description
Ethernet based technologies are emerging as the ubiquitous de facto form of communication due to their interoperability, capacity, cost, and reliability. Traditional Ethernet is designed with the goal of delivering best effort services. However, several real time and control applications require more precise deterministic requirements and Ultra Low Latency (ULL), that Ethernet cannot be used for. Current Industrial Automation and Control Systems (IACS) applications use semi-proprietary technologies that provide deterministic communication behavior for sporadic and periodic traffic, but can lead to closed systems that do not interoperate effectively. The convergence between the informational and operational technologies in modern industrial control networks cannot be achieved using traditional Ethernet. Time Sensitive Networking (TSN) is a suite of IEEE standards designed by augmenting traditional Ethernet with real time deterministic properties ideal for Digital Signal Processing (DSP) applications. Similarly, Deterministic Networking (DetNet) is a Internet Engineering Task Force (IETF) standardization that enhances the network layer with the required deterministic properties needed for IACS applications. This dissertation provides an in-depth survey and literature review on both standards/research and 5G related material on ULL. Recognizing the limitations of several features of the standards, this dissertation provides an empirical evaluation of these approaches and presents novel enhancements to the shapers and schedulers involved in TSN. More specifically, this dissertation investigates Time Aware Shaper (TAS), Asynchronous Traffic Shaper (ATS), and Cyclic Queuing and Forwarding (CQF) schedulers. Moreover, the IEEE 802.1Qcc, centralized management and control, and the IEEE 802.1Qbv can be used to manage and control scheduled traffic streams with periodic properties along with best-effort traffic on the same network infrastructure. Both the centralized network/distributed user model (hybrid model) and the fully-distributed (decentralized) IEEE 802.1Qcc model are examined on a typical industrial control network with the goal of maximizing scheduled traffic streams. Finally, since industrial applications and cyber-physical systems require timely delivery, any channel or node faults can cause severe disruption to the operational continuity of the application. Therefore, the IEEE 802.1CB, Frame Replication and Elimination for Reliability (FRER), is examined and tested using machine learning models to predict faulty scenarios and issue remedies seamlessly.
ContributorsNasrallah, Ahmed (Author) / Reisslein, Martin (Thesis advisor) / Syrotiuk, Violet R. (Committee member) / LiKamWa, Robert (Committee member) / Thyagaturu, Akhilesh (Committee member) / Arizona State University (Publisher)
Created2022
Description
The first chapter uses data on birthplaces of 2,065 Chief Executive Officers (CEO) and a county-level measure of cultural individualism based on the westward expansion in American history to establish a positive relation between CEO cultural individ- ualism and corporate innovation. Difference-in-differences estimations around CEO turnovers support the causality. Individualistic CEOs increase innovation by creating an innovative corporate culture, providing more flexibility to employees, and tolerance for failure.The second chapter develops a model to study the corporate board structure and communication. Outside directors are related to potential competitors. As a result, they can bring valuable advice and cause information leakage. The firm needs to decide whether to have outside directors on the board. In the presence of the outside director, the other directors need to determine whether to communicate.
ContributorsZhang, Fan (Author) / Boguth, Oliver (Thesis advisor) / Babenko, Ilona (Committee member) / Schiller, Christoph (Committee member) / Wang, Jessie Jiaxu (Committee member) / Arizona State University (Publisher)
Created2022
Description
Western cultures on the whole have a particular fascination surrounding tattoos, and academia is no different. There are numerous studies that discuss why people get tattoos and what peoples’ perceptions of those with tattoos are. However, there has only been a minuscule amount of research on the ones who even make tattoos possible: Tattoo artists. This work endeavors to provide a platform for tattoo artists to share their stories and experiences, and, in turn, help provide academia and the public at-large with a better understanding of tattoo artist identity and how the tattoo artist residual community functions and defines itself. Through ethnography, ethnographic interviews, and autoethnography, the everyday lives of tattoo artists will be explored. This work also seeks to provide an understanding of the history, skillsets, artistry, and creativity of Western tattoo artists, while simultaneously arguing for how tattoos and their creators can open the world of “fine art” to a broader audience and make it more accessible for all.
ContributorsHawn, Allison (Author) / Mean, Lindsey (Thesis advisor) / Schleif, Corine (Committee member) / Guerrero, Laura (Committee member) / Arizona State University (Publisher)
Created2022
Description
During uncertain situations such as a crisis or risk scenario, journalists experience challenges in filtering, verifying, and curating information and adapting to the new work conditions. Utilizing Sensemaking Theory, this qualitative study aims to understand how journalists construct reporting decisions on uncertain scientific topics, given the potential impact of these stories on the public’s understanding and acceptance of science. The study focuses on Kuwaiti journalists’ handling of science and health information during the outbreak of the Novel Coronavirus Disease of 2019 (COVID‐19). The research adopts a narrative approach, conducting in-depth interviews with science reporters and managing editors from digital news outlets in Kuwait. Thematic analysis of the data indicates that journalists’ handling of COVID-19 uncertain science news was mainly influenced by interests, emotions, external pressures, personal stances, and organizational alignment rather than a thorough evaluation of claims. This suggests a lack of expertise and competence in effectively evaluating and interpreting science news.
The study identifies six primary sensemaking approaches used by science journalists and reveals the implicit connotations that underlie Kuwaiti journalists’ roles, which are heavily influenced by their professional, social, and cultural realities. The findings suggest that journalists’ perceptions of their surrounding environment, including their country’s level of scientific contribution, public interest in science, and the overall state of journalism, are important dimensions influencing their perception of their role. Additionally, the study adds to the body of research on gatekeeping by highlighting the influence of sensemaking on journalists’ resistance and compliance with a gate and how this may sometimes lead to overlooking a gate’s presence.
Moreover, the study contributes to understanding journalists’ news values and value prioritization during uncertain times. It emphasizes the reciprocal relationship between sensemaking and news values, where values serve as both selection and sensemaking devices. The findings also shed light on how journalists justify their control over uncertain information dissemination, using uncertainty, audience perception, and social responsibility to legitimize their actions and deflect criticism. The insights gained from this study have significant implications for journalistic practices, ethics, and responsibilities in the context of uncertainty and health crises.
ContributorsAlshehab, Ahmad Sh (Author) / Gilpin, Dawn (Thesis advisor) / Silcock, B. William (Committee member) / Thornton, Leslie-Jean (Committee member) / Ebrahim, Husain (Committee member) / Arizona State University (Publisher)
Created2023
Description
Communications around sustainability have been found to be incongruent with eliciting the transformative change required to address global climate change and its' repercussions. Recent research has been exploring storytelling in sustainability, specifically with an emphasis on reflexive and emancipatory methods. These methods encourage embracing and contextualizing complexity and intend to target entire cognitive hierarchies. This study explores the possibility of using emancipatory and reflexive storytelling as a tool to change attitudes pertaining to the Valley Metro Light Rail, an example of a complex sustainability mitigation effort. I explore this in four steps: 1) Conducted a pre-survey to gauge preexisting attitudes and predispositions; 2) Provided a narrative that uses storytelling methodologies of reflexivity and emancipation through a story about the light rail; 3) Conducted a post-survey to gauge attitude shift resulting from the narrative intervention; 4) Facilitated a focus group discussion to examine impact qualitatively. These steps intended to provide an answer to the question: How does emancipatory and reflexive storytelling impact affective, cognitive and conative attitudes regarding local alternative transportation? By using tripartite attitude model, qualitative and quantitative analysis this paper determines that reflexive and emancipatory storytelling impacts attitudinal structures. The impact is marginal in the survey response, though the shift indicated a narrowing of participant responses towards one another, indicative of participants subscribing to emancipation and reflexivity of their held attitudes. From the group discussion, it was evident from qualitative responses that participants engaged in emancipating themselves from their held attitudes and reflected upon them. In doing so they engaged in collaboration to make suggestions and suggest actions to help those with experiences that differed from their own. Though this research doesn’t provide conclusive evidence, it opens the door for future research to assess these methodologies as a tool to elicit shared values, beliefs and norms, which are necessary for collective action leading to transformative change in response to global climate change.
ContributorsSwanson, Jake Ryan (Author) / Roseland, Mark (Thesis advisor) / Larson, Kelli (Committee member) / Calhoun, Craig (Committee member) / Schoon, Michael (Committee member) / Arizona State University (Publisher)
Created2023
Description
Collaborative Video Viewing (CVV) transforms passive video-based learning into an engaging, active process. While collaborative modes have different affordances that could potentially influence knowledge co-construction, no study has directly assessed the impact of collaborative modes in CVV activities. Therefore, this current study seeks to investigate how collaborative modes influence learning outcomes, learning engagement, group interaction and the co-construction process.The study utilized a within-subject, counterbalanced experimental design, in which each participating undergraduate student was paired in dyads. These dyads were assigned to engage in two separate CVV sessions: one using synchronous voice-based collaborative mode (SV) and the other using asynchronous text-based collaborative mode (AT). After each session, participants completed a test consisting of retention and application questions. ANCOVA was utilized to analyze the test scores.
To ascertain if the different scores were a result of varying levels of learning engagement, dyad discussions were coded using ICAP coding (Chi & Wylie, 2014). Furthermore, to delve deeper into the group interaction mechanism in SV and AT, a codebook was developed to analyze the discourse that occurred during dyad interaction. Sequential analysis and thematic narrative analysis were employed to visualize interaction patterns and the co-construction process.
The findings indicated that, generally, SV dyads performed better on application scores and have significantly higher interactive learning engagement than AT dyads. In line with ICAP predictions, the higher-score groups in both SV and AT engaged in more generative processes, leading to more constructive and interactive comments than lower-scoring groups. In terms of group interaction, both SV and AT primarily use descriptive discourse for co-explanation. However, the SV groups exclusively introduce discourse expressing uncertainty, which subsequently leads to group negotiation. The study identified distinct knowledge co-construction phases, including (a) co-explanation, (b) negotiation, and (c) application. Although the co-explanation phase is the most frequent in all dyad scores in both SV and AT, the negotiation phase appears to differentiate low-high score dyads from high-high score dyads.
These findings hold research implications for understanding learning engagement and group interaction in various online collaborative modes, as well as for the instructional design of active video-based learning through collaborative video viewing.
ContributorsTechawitthayachinda, Ratrapee (Author) / Chi, Michelene (Thesis advisor) / Hong, Yi-Chun (Thesis advisor) / Nelson, Brian (Committee member) / Arizona State University (Publisher)
Created2023
Description
This dissertation develops an Indigenous rhetorical praxis of futurity, whichserves as an anticolonial methodology to activate indigeneity as a condition of possibility within communication studies. This approach seeks to apprehend and expose the persistence of colonialism and imperialism, particularly as these structures continue to shape and impact Indigenous lands and lives. It is promiscuous in practice, building from Indigenous political and cultural domains while simultaneously traversing the networks of colonialist ideologies to rearticulate rhetorical theoretical and methodological practices that are infused in anticolonial consciousness.
To illuminate this praxis, I analyze three Indigenous speculative fiction novels authored by Indigenous people: Elatsoe by Darcie Little Badger (Lipan Apache Tribe of Texas), The Marrow Thieves by Cherie Dimaline (Georgian Bay Métis), and The Only Good Indians by Stephen Graham Jones (Blackfeet). I concentrate on two primary aspects within the novels studied, including the authors’ articulations of spatial and affective relations as they inform Indigenous futurity. My focus on spatiality interrogates how the authors redefine colonial spaces and their impacts on bodies, identities, communities, and kinship formations. The analysis of affect explores how Indigenous desires, intimacies, and sensual embodiments are employed to dismantle liberalism, democracy, and discourses of rights and recognition.
These examinations uncover the productions of indigeneity, colonialism, and sovereignty to enhance an understanding of the modes of dispossession through which subjectivities are constructed and deconstructed. Overall, this dissertation carves a space for Indigenous futures in communication studies and makes contributions to critical rhetorical studies, queer intercultural communication research, and the emerging subfield of Indigenous communication studies.
ContributorsStanley, Liahnna (Author) / LeMaster, Lore/tta (Thesis advisor) / Kim, Heewon (Thesis advisor) / Vicenti Carpio, Myla (Committee member) / Lechuga, Michael (Committee member) / Arizona State University (Publisher)
Created2023
Description
Massively multiplayer online games (MMOs) offer community spaces where players can interact and develop a diverse range of skills online, such as communication and socialization, that can be applied offline. Designing more inclusive community spaces is crucial to give a more diverse range of individuals the chance to develop these skills. One way to add diversity to an online community space is to attract players with diverse personalities and play styles. This study is a qualitative exploration of personality and play in Final Fantasy XIV (FFXIV). The specific research question is: what kinds of patterns exist in player personality and in the choices players make in a massively multi-player online (MMO) game Subjects were given the Big 5 personality survey to measure the five core personality dimensions. The survey also included FFXIV-specific items about in-game preferences and play styles of the players, and it concluded with open-ended questions that allowed subjects to explain certain choices. Thematic analysis was used to find patterns in the open-ended questions. The results of this exploratory study indicate that the players in this community are mostly casual and play FFXIV for the content and social aspects of the game. They enjoyed the customization options and gameplay of FFXIV. It is important to be open to the different backgrounds of players who join the Free Company (FC) and to accommodate their preferences and choices in the game. Consistent player interactions and activities with other members in their FC help to create a sense of community.
ContributorsFlor, Michelle Kaitlyn (Author) / Wise, Greg (Thesis advisor) / Mean, Lindsey (Committee member) / Halavais, Alexander (Committee member) / Arizona State University (Publisher)
Created2023
Description
I center my analysis on Amazon’s recent foray into alternative history The Man in the High Castle premised on Philip K. Dick’s 1962 novel of the same name. Amazon Studio’s production The Man in the High Castle builds upon the premise of an alternative history where World War II ends differently. Here, the diegetic narrative depicts a United States split into three distinct regions: the east coast, now part of the German Reich; the Neutral Zone, or most of the Midwest and the Rocky Mountains; and the west coast, controlled by Japanese Empire. The film version debuted in 2015 as a series extending to four seasons of 10 episodes a piece by 2019. I argue that the show takes cues from modern political tensions, the rise of the alt-right and “post-truth” media manipulations, to intentionally destabilize viewers’ memories of the historical past. By blurring the boundaries between the diegetic reality of the show and our accepted version of history, The Man in the High Castle disrupts the facility in which the viewer assumes alignment with memory and past, opting instead for a complicated refiguring of the political present. Here I articulate how film as a medium tampers with the viewer’s ontological understanding of image by collapsing history and fiction together. Additionally, the capacity of film to provoke empathy from viewers complicates the universal condemnation of Nazism we are familiar with and permits viewers to see the banality of evil in this reimagined history. Finally, I discuss how film as a medium capitalizes on the incompleteness of memory and the loopholes of history to fabricate viewer memory.
ContributorsAbele, Kelsey Taylor (Author) / Brouwer, Daniel (Thesis advisor) / Carlson, Adina (Committee member) / Hedberg Olenina, Ana (Committee member) / Arizona State University (Publisher)
Created2020