Thesis (Ph. D.)--Swinburne University of Technology, 2005. / Title from PDF title page (viewed on Mar. 3, 2006). "14 April 2005." Includes bibliographical references.

Thesis (Ed.D.)--Duquesne University, 2008. / Title from document title page. Abstract included in electronic submission form. Includes bibliographical references (p. 286-309) and index.

Thesis (Ph. D.)--Ohio State University, 2009. / Title from first page of PDF file. Includes vita. Includes bibliographical references (p. 205-214).

In this thesis, we attempt to revisit the problem of multi-party conferencing from a practical perspective, and tore think the design space involved in this problem. We believe that an emphasis on low end-to-end delays between any two parties in the conference is a must, and the source sending rate in a session should adapt to bandwidth availability and congestion. We present Celerity, a multi-party conferencing solution specifically designed to achieve our objectives. It is entirely Peer-to-Peer(P2P), and as such eliminating the cost of maintaining centrally administered servers. It is designed to deliver video with low end-to-end delays, at quality levels commensurate with available network resources over arbitrary network topologies where bottlenecks can be anywhere in the network. This is in contrast to commonly assumed P2P scenarios where bandwidth bottlenecks reside only at the edge of the network. The highlight in our design is a distributed and adaptive rate control protocol, that can discover and adapt to arbitrary topologies and network conditions quickly, converging to efficient link rate allocations allowed by the underlying network. In accordance with adaptive link rate control, source video encoding rates are also dynamically controlled to op-timize video quality in arbitrary and unpredictable network conditions. Celerity runs on the application layer and uses UDP to deliver the data. With the distributed rate control protocol, Celerity can deliver video at quality levels without the acknowledge of the underlying network topology, bandwidth, and the routing. We have implemented Celerity in a prototype system, and demonstrateits su¬perior performance over existing solutions in a local experimental test bed and over the Internet. In addition, using Celerity we have developed a multi-party conferencing system which provides real-time video and audio communication and allows users to dynamically join and leave, it achieves better user experience(low delay and high throughput) than existing products. / Chen, Xiangwen. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2012. / Includes bibliographical references (leaves 66-68). / Abstract --- p.i / Acknowledgement --- p.iii / Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Motivation --- p.1 / Chapter 1.2 --- Contribution --- p.2 / Chapter 1.3 --- Thesis Organization --- p.4 / Chapter 2 --- Related Work --- p.5 / Chapter 3 --- Problem Formulation and Celerity Overview --- p.7 / Chapter 3.1 --- Settings --- p.7 / Chapter 3.2 --- Problem Formulation --- p.9 / Chapter 3.3 --- Celerity Overview --- p.10 / Chapter 4 --- Packing Delay-bounded Trees --- p.13 / Chapter 5 --- Overlay Link Rate Control --- p.18 / Chapter 5.1 --- Considering Both Delay and Loss --- p.18 / Chapter 5.2 --- A Loss-Delay Based Primal-Subgradient-Dual Algorithm --- p.20 / Chapter 5.3 --- Computing Subgradients of R{U+2098}(c{U+2098}, D) --- p.23 / Chapter 6 --- PRACTICAL IMPLEMENTATION --- p.26 / Chapter 6.1 --- Peer Functionality --- p.26 / Chapter 6.2 --- Critical Cut Calculation --- p.29 / Chapter 6.3 --- Utility Function --- p.29 / Chapter 6.4 --- Opportunistic Local Loss Recovery --- p.29 / Chapter 6.5 --- Fast Bootstrapping --- p.30 / Chapter 6.6 --- Operation Overhead --- p.30 / Chapter 6.7 --- Peer Computation Overhead --- p.31 / Chapter 6.8 --- System Implementation --- p.32 / Chapter 7 --- Experiments --- p.34 / Chapter 7.1 --- LAN Testbed Experiments --- p.34 / Chapter 7.1.1 --- Absence of Network Dynamics --- p.36 / Chapter 7.1.2 --- Cross Traffic --- p.39 / Chapter 7.1.3 --- Link Failure --- p.40 / Chapter 7.2 --- Peer Dynamics Experiments --- p.41 / Chapter 7.3 --- Internet Experiments --- p.42 / Chapter 8 --- Concluding Remarks --- p.46 / Chapter A --- Packing Delay-bounded Trees in the Presence of Helpers --- p.47 / Chapter B --- Proof of Theorem 1 and Theorem 3 --- p.50 / Chapter C --- Proof of Corollary 1 and Corollary 2 --- p.56 / Chapter D --- Proof of Proposition 1 --- p.58 / Chapter E --- Proof of Theorem 2 --- p.60 / Bibliography --- p.66

This dissertation considers the problem of scheduling deadline-constrained packets in networks, an increasingly relevant problem, which due to the rise of time-sensitive applications such as teleconferencing and video streaming, has recently received renewed attention. To accommodate a diverse range of environments and scenarios, our work investigates single-hop and multi-hop networks, across various traffic models and network conditions, including wired and wireless settings. We propose algorithms in each setting, with their performance evaluated by considering commonly used benchmarks in the related literature, such as the attained fraction of the real-time capacity region achieved in single-hop networks and the maximization of the cumulative weight of packets reaching their destinations within their deadlines in multi-hop networks. We explore traffic which is either worst-case, or stochastic, and provide different performance guarantees in each case. The first part of our study focuses on scheduling real-time traffic in single-hop wireless networks with conflict-graph interference models. We propose randomized policies that achieve higher real-time efficiency ratios, compared to state-of-the-art existing algorithms, such as the Largest-Deficit-First algorithm. The research then extends to single-hop wireless networks with unreliable links due to channel fading, designing randomized algorithms that achieve efficiency ratios strictly higher than traditional scheduling algorithms, such as Maximum-Weight Scheduling. The dissertation proceeds to examine online admission, routing, and scheduling algorithms for multi-hop wireless networks under a general interference graph model. It presents online algorithms that are competitive with the optimal offline algorithms and provides upper bounds on performance which demonstrate the asymptotic optimality of these results. Simulation results illustrate significant improvements over prior approaches. Furthermore, the research addresses the problem of scheduling packets with end-to-end deadline constraints in both wired and wireless multi-hop networks, in the case of stochastic traffic. It illustrates the first near-optimal approximation algorithms under nontrivial assumptions on traffic and link capacity, showcasing significant improvements over worst-case algorithms in practical settings. In conclusion, this dissertation contributes scheduling algorithms for deadline-constrained packet delivery in single and multi-hop networks, under various traffic and interference models, and in both wired and wireless settings. The proposed algorithms materially improve the state-of-the-art performance guarantees in each case.

Thesis (Ph.D.)--Syracuse University, 2008. / "Publication number: AAT 3323039."

Children with dysarthria due to cerebral palsy (CP) often face barriers to accessing speech research participation and clinical speech services. Utilizing at-home online videoconferencing may be a practical solution to these accessibility barriers if the speech signal yielded from online recordings is valid. This study aimed to determine the validity of acoustic and perceptual measures obtained from speech data collected (remotely) online from children with dysarthria due to CP. The speech of 17 children with dysarthria was recorded by means of two data collection methods performed simultaneously: 1) via Zoom video communications and 2) via a professional audio recording device sent to the children's parents. A calibration procedure permitted the children’s original vocal sound pressure level (SPL) to be represented in the speech signal. Acoustic and perceptual measures extracted from the two recordings were compared in order to determine the validity of speech data collected online from the children. The acoustic measures, obtained from 1,690 tokens of words and 605 tokens of sentences, were the second formant (F2) range of diphthongs, F2 slope of diphthongs, fricative-affricate duration difference, word duration/articulation rate, mean fundamental frequency (F0), F0 variation, SPL, shimmer, signal-to-noise ratio (SNR), and cepstral peak prominence (CPP). Perceptual measures were 187 adult listeners’ orthographic transcription accuracy and visual analog scale (VAS) ratings of the children’s speech, collected via an online crowdsourced platform. Acoustic measures of F2 range of diphthongs, fricative-affricate duration difference, word duration, and mean F0 reached the validity criterion of rrm-value .75 and demonstrated good agreement within the predetermined clinical criterion at both word and sentence levels. Moreover, SPL met the validity criterion and exhibited good agreement at the word level; however, it failed to meet the validity criterion and demonstrated agreement outside the clinical criterion at the sentence level. The F2 slope of diphthongs showed a strong correlation between online and audio-device recordings and reached the validity criterion; however, it did not show agreement within the clinical criterion at either word or sentence level. Perturbation-based, noise-based, and cepstral measures (i.e., F0 variation, shimmer, SNR, CPP) showed a wide range of correlation and agreement outside of clinical criteria between online and audio-device recordings. Both perceptual measures showed strong correlations between the two recording methods, reaching the validity criterion. Findings suggest that measures that reflect physiological aspects of speech production may be valid and appropriate to extract from online recordings. However, measures capturing noise and variability within the signal may not be valid when obtained from online recordings. Additionally, the results suggest that perceptual measures of listeners’ transcription and ratings from online recordings may be valid to use for research and clinical purposes. Therefore, careful consideration of the appropriate measures and their limitations is essential to obtaining accurate results when extracting measures from online recordings. These findings provide a valuable foundation of evidence supporting the use of online videoconferencing platforms for several acoustic and perceptual measures commonly implemented in speech research, clinical assessment, and treatment.

The importance of access to quality physical education (PE) among children is well-documented. The onset of the COVID-19 pandemic, however, resulted in significant shifts in PE curriculum delivery alongside a rapid uptake by PE teachers of new technologies. Although some research about integrating technology into teaching does exist, there is very little data about virtual learning in elementary school, particularly in the context of physical education. There are also clear gaps in the literature about teaching PE virtually during a pandemic. As such and in this study, I sought to fill a critical gap in the existing literature by identifying what specific factors shaped elementary physical education delivery during the COVID-19 pandemic, as well as barriers and facilitators to successful curriculum delivery, and I drew implications for future emergency response needs.This mixed-methods study examined elementary physical education teachers’ perceptions of teaching virtually during the spring of 2020 and/or 2020-2021 school year. The study’s sample drew on PE teachers from urban, rural, and suburban settings across the US, which included diverse experiences to explore teachers’ perceptions of virtual teaching during the COVID-19 pandemic. Surveys and focus groups were utilized. Results from this study elucidated that physical education teachers were challenged by limited space, equipment, internet use, and distraction within the environment when teaching. However, teachers in this sample also discussed their tenacity to help their students stay active by delivering supplies to families, posting on social media, and teaching how to make alternative equipment. Teachers also reported that the more support they received (for example, via social emotional support and also specific technology support), the less stress they felt during remote teaching. At the same time, the higher the teacher perception on live lesson participation, the more efficacious the teachers felt. The expectations of PE teachers during COVID varied from region to region, and the ever-changing schedules made teaching PE that more difficult. Although there has been some research on teaching virtually, before the pandemic there was very little research about specifically teaching elementary PE virtually. The need to pivot to remote instruction is part of our future. The implication of this work helps support the need for further education of public health goals. The need for a platform that supports PE and elementary age children is needed to best support this work. Using technology as an enrichment and supplement for PE to help reach this goal could be a positive outcome of this pandemic. The use of virtual platforms will also help deliver PE content to families and allow for technology skill development through targeted practice for any future need to pivot to remote.

Information and communication technology (ICT) has dominated our lives and the way we learn in such a way that, without it, our way of life becomes obsolete. This study explored challenges experienced by tutors in facilitating teaching and learning through the use of videoconference (VC) technology in an open and distance learning (ODL) environment. These challenges are exacerbated by the fact that most tutors, although highly qualified, do not have teaching methodologies with their qualifications at the time of their employment as tutors. It is believed that if these challenges could be given attention, VC technology would serve as an effective facilitation tool for bridging the distance in teaching and learning. Based on qualitative research approach, this study followed a qualitative phenomenological research design. Qualitative data was collected from individual semi-structured interviews with specific VC tutors; tutorial observations based on tutorials offered in the VC environment; and focus group interviews with students who attended tutorials through VC technology. Informed by the Community of inquiry (CoI) theory, the study answered the following main research question: “What are the experiences of tutors in applying instructional methodologies during VC tutorials?” The findings indicate lack of skills and reluctance in applying various active facilitation methods by VC tutors, insufficient technology training intervention by the ODL institution under study, technical challenges of VC technology in teaching and learning, and lack of monitoring systems during VC discussions. The findings further featured various factors that contribute to tutors’ ability in promoting interactivity during VC tutorials. In conclusion, this study clearly indicates that instructional methodologies used in VC tutorials cannot contribute to a meaningful teaching and learning, and thus make interactivity absent throughout VC sessions. Based on these findings, and suggestions for further research, the study therefore recommends acceleration in tutor training on exploitation and integration of VC technology with various suitable teaching methodologies. / Curriculum and Instructional Studies / M. Ed. (Didactics)