Homomorphic encryption (HE) enables computations on encrypted data making it possible to perform calculations on a server without sharing the secret key for decryption. HE is relatively new and has seen significant improvements in recent years in terms of speed of encryption, decryption, operations, and the number of operations possible to perform in a row without damaging the ciphertext. These improvements open up new possibilities, such as using HE in voice over IP (VoIP) and still being able to mix audio streams at the server without decrypting them, creating a scalable and secure application.  This thesis evaluates the performance of three HE schemes, BGV, BFV, and CKKS, implemented by the open-source library Palisade and compares their performance to a non-HE scheme AES in terms of encryption time, decryption time and end-to-end latency. Furthermore, the performance of mixing with HE-encrypted audio files is evaluated. The work is a proof-of-concept that allows the user to send audio files of different sample rates and batch sizes to compare the performance. It also investigates the Quality of Experience by measuring the audio quality after the mixing, using PESQ and POLQA. The results show that BGV performs almost as good as AES for higher batch sizes, while BFV performs almost as good in most cases and trails behind in others. CKKS, on the other hand, is the slowest scheme but is still fast enough in some cases to be considered a possible encryption scheme. Furthermore, the tests show that the HE schemes do not decrease the listening quality much according to PESQ and POLQA, as all tests concluded a result that is considered good or excellent. The number of files being mixed had a negative impact on narrowband and wideband audio streams, while it did not affect superwideband and fullband.

This project will be based in an objective and as well as subjective study related to Quality of Experience in a video conference application, appear.in. Indeed the study puts emphasis on finding possible correlations between Quality of Service parameters, that in the study are represented by some of the most meaningful network parameters, and contextual parameters with Quality of Experience. To achieve this the study was based in two different scenarios using two test environments. One is based on having an all free test and the other conducted in a created test-bad for monitoring and altering network parameters to see how user respond to the changes. Both scenarios were accompanied by a survey that provided useful information about the subjective perception of different individuals that took part in the testing phase.The project is divided in two phases where we set up the required environments for the test and then we process results to find correlation between the above mentioned parameters.In the end of the project all the results and the conclusions are presented providing a clearer view for what was done. The project itself might represent a good foundation to be used in the future for other studies related to video conferencing application.

There has been an increasing growth in the use of technology resources in traditional classroom styled higher education courses. This growth has received with both optimism and criticism. One of the issues critics have posed is that the use of technology resources does little, if anything, to improve student learning. As a result, this research examined if the use of technology contributes to student learning outcomes and student engagement activities, above and beyond student demographic variables. Specifically, this study investigated if the use of computer mediated conferencing (CMC) tools (i.e., email and electronic discussion boards) and computer aided instructional (CAI) resources (i.e., use of the computer and the Internet) contribute to student learning. Included in the sample were 2000 college students, which were randomly drawn from the 2003 College Student Experience Questionnaire database. The survey included 53 Likert scale items with reliability ranges from .78 to .88 on each of the composite scales. For the data analysis, eight multiple regressions were conducted on student learning outcomes and student learning engagement. Student learning outcomes included four composite scales, measuring students' personal and social development, general education gains, intellectual development, science and technology gains, and vocational preparation. The student engagement scale was comprised of three composite scales, which included faculty interactions, social, political and scientific discussions, and diversity and social interactions. The findings revealed that the use of technology resources does contribute to student learning, above and beyond student's background variables. The model inclusive of technology variables explained 4% to 7% of the gains in student learning, while student background variables contributed .03% to 2% of the gains. The findings suggest incorporating the use of technology can aid students in the learning process, though the effect size was fairly modest in most cases. The use of computer mediated conferencing and computer assisted learning tools should be used in combination with traditional classroom instructions to have the best effects. / Ph. D.

<p dir="ltr">In recent years, video conferencing technology has gained widespread use, driving the demand for enhanced virtual communication experiences. However, survey shows that users are highly concerned about information leaks from their video backgrounds and often re- port difficulties maintaining attention during long meetings. This dissertation focuses on improving privacy and immersion in video conferencing. To improve segmentation quality and inter-frame segmentation consistency, sources of temporal guidance are benchmarked. Furthermore, we develop a lightweight deep neural network with efficient temporal guid- ance for real-time portrait video segmentation. The method achieves good balance between processing time and segmentation quality, making it ideal for real-time applications such as background blurring and replacement. To promote immersiveness in video conferencing, we propose a cost-effective telepresence system that delivers more immersive viewing ex- periences. The system integrates multi-view capture, spatial view interpolation, and view rendering. Leveraging a fully synthetic multi-view portrait dataset, the quality of the spatial view interpolation method is significantly improved. Additionally, we introduce an effective multi-stage network which significantly reduces the computation cost in generating multiple interpolated views at finer scales without sacrificing image quality. Furthermore, a simplified system with only two camera inputs is explored, which utilizes pose information to assist spatial view interpolation. The proposed telepresence system offers an immersive multi-angle viewing experience.</p>

Thesis (PhD)--Macquarie University, Division of Information and Communication Sciences, Computing Department, 2008. / Bibliography: p. 503-514. / This study investigated learning design in a web-conferencing environment based on three semesters of lessons conducted as part of an introductory programming subject. As well as characterizing the nature of discourse and interaction, the study focused on how the design of the interface, activity and task type affected collaboration and learning. Engeström's (1987) Activity Theory based upon a socio-constructivist view of learning was used to frame the analysis. --Interface designs incorporated theory relating to graphical user interface design, multimedia learning, and findings from the cognitive sciences. Activity designs were differentiated based on the degree of student ownership, from teacher-centred (transmissive) approaches, to teacher-led (guided interaction) approaches, to student-centred (collaborative group-work) designs. Types of tasks were considered on the basis of their level of knowledge (declarative, procedural and conceptual), their character (authenticity, situatedness) and their domain specific nature (in the field of computer science education). The effects of the different interface, activity and task designs on collaboration and mental model formation were explored. --A mixed method approach to analysis was adopted, incorporating a design-based research study and a multimodal discourse analysis. The design-based research allowed a broader, more interpretivistic and process focused analysis to be conducted, based on the strategic redesigns that occurred between iterations of the subject. The multimodal discourse analysis enabled more detailed, objective and outcomes based measurements of the subject of discourse, the nature of interactions and the types of modalities used to mediate learning. Triangulating data from the design-based research study and the multimodal discourse analysis provided a more complete description of phenomena and promoted greater reliability. --Results include the way in which different modalities afforded different possibilities for representing, and how combinations of those modalities could be effectively integrated by applying multimedia learning principles. Student-centred learning designs increased student involvement, allowing them to take greater ownership over the content and to more fully share their mental models. Authentic, meaningful problem solving tasks promoted greater student engagement. The capacity to dynamically redesign the interface based on the collaborative and cognitive requirements of the learning episode supported more effective implementation of conversational (Laurillard, 2002) approaches to learning. --More effective interaction and collaboration resulted from prescribing patterns of engagement, managing activity and technology so that student discourse could focus on content, and providing guidance regarding semiotic representational forms so that students could concentrate on applying those representations rather than inventing them. Teacher and student virtual classroom competencies critically influenced collaboration and learning. --Based on the findings in this study, a framework of nine pedagogical patterns for teaching and learning in web-conferencing environments is proposed. The framework provides an integrated approach to learning design that relates the interface design with the activity design and the level of knowledge (task type). / Mode of access: World Wide Web. / vii, 514 p. ill. (some col.)

This investigation has been carried out at the RoyalInstitute of Technology (KTH) in Stockholm. The main goal hasbeen to investigate the factors determining the production of asense of presence and reality in video mediated communication.Presenceis in these studies defines as the subjectiveexperience of being together in one place when one isphysically situated in another. Presence is an emergentproperty; it has no physicality, but arises as a mentalsensation. Special attention has been paid to spatial factors,embodiment issues, and narrative elements related to theproduction of presence. A context map has been used in order to model the semanticsof presence production and to visualize the relationshipsbetween the determining factors. The conclusions may besummarized as follows:     Knowledge about physical and extended spaces and bodiesand of the shifting of attention between these is importantin presence production.     Well planned design of physical and virtual spacesenhances the sense of presence.     Coherent design and production of mediated embodiment canenhance the sense of presence.     Conscious use of content characteristics, e.g., goodstorytelling, can enhance the sense of presence.     Different communication modes need the support ofdifferent combinations of presence production factors.     Even technically poorly mediated communication maysupport a sense of presence and reality if the storytellingis good.     The human sensory environment should be supported by asense of non-mediation, technological transparency, on theplane of discourse.     The results indicate that individual differencesinfluence the sense of presence and reality. The perception of video mediated communication evolves aspeople become daily users. People seem to intuitively begin tointerpret new types of mediated cues, adding what is missing incomparison to a real time physical communicationexperience. Keywords:Telepresence, presence, social presence,co-presence, concept modeling, virtual reality, person space,task space, narration, video mediated communication, videoconferencing.

A pesquisa consiste numa análise comparativa entre três eventos no contexto das comemorações dos 500 anos da chegada dos portugueses ao Brasil: uma mostra cultural em São Paulo, intitulada Bienal + 500; um ato oficial em Porto Seguro, onde foi assinado um Tratado de Cooperação e Amizade entre Brasil e Portugal e um projeto alternativo de arte e tecnologia denominado Projeto Perforum este último concebido por Artur Matuck em colaboração com um grupo de artistas inovadores, que contestavam a representação eurocêntrica e triunfalista dos eventos oficialmente propostos. O Projeto Perforum pretendia envolver grupos étnicos e culturas que participaram do processo de formação da nação brasileira, buscando o diálogo entre elas. Por outro lado, em termos de linguagem artística, experimentava-se com a Arte Telemática compreendendo-se esta como a arte desenvolvida no eixo das telecomunicações, ou seja, aquela que ocorre da transmissão eletrônica de informações, pelo uso de telefones, equipamentos de fax, redes de computadores, televisão, satélites ou videoconferências. / This research aims to provide a comparative analysis of three events in the context of the celebrations of the 500th anniversary of the discovery of Brazil: A cultural exhibition in Sao Paulo, titled Bienal + 500, an official diplomatic act in Porto Seguro, where it was signed a Treaty of Friendship and Cooperation between Brazil and Portugal, and an alternative project of art and technology called Project Perforum the latter designed by Artur Matuck in collaboration with a group of innovative artists who challenged the triumphalist eurocentric officially proposed celebrations by the time. The Project Perforum intended to involve ethnic groups and cultures who participated in the process of formation of the Brazilian nation, intending a dialogical paradigm between these cultures. Moreover it proposed a series of experiments with the emerging telematic art this being understood as the art developed in the sphere of telecommunication, that is, one that occurs while transmitting electronic information through the use of mobile equipment, fax, computer networks, television, satellites, or videoconferencing.