This doctoral thesis examines different attributes of large scale group communication systems such as scalability, security and mobility by studying two different prototype systems - mIR (multicast Interactive Radio) and MES (Mobile E-meeting Services). mIR is a system for large scale real-time music distribution, designed as an interactive radio system for the Internet. MES is a collection of tools for improving the use of e-meeting and video conferencing tools in a mobile environment. The mIR prototype has been used to study scalability and security. Scalability in mIR concerns how to support as many users as possible without degrading the experience. This is achieved using IP multicast together with algorithms that limits the bandwidth usage regardless of the number of users. The work on security have focused on copy prevention through digital watermarking. By adding a unique watermark, i.e. a fingerprint, to each media copy a pirated copy can be traced back to a specific user, which can act as a deterrent. The thesis shows how we can combine the different goals of fingerprinting and IP-multicast while still maintaining the scalability features of multicast. Many issues need to be considered if e-meetings and video conferencing will become widespread and popular. Scalability and security, discussed in the first part of the thesis are two examples, and the second part of the thesis tries to address a third issue: mobility. In particular we are interested in enabling access to an e-meeting in a mobile environment, where we often have difficult conditions such as bad network connections, the user only have access to the Internet through a web browser or the available devices are small and limited. In many cases it is currently impossible to participate in an e-meeting when you're not in the office. The prototype system developed in the second part of the thesis aims to enable participation from any location and device that have some sort of Internet connection. We try to achieve this by allowing a mobile user to access an e-meeting session from a web browser or from a Java enabled mobile phone. Further, the system makes it possible to review missed events in an e-meeting as it is likely that there are many times where no Internet connection at all is available. The general style of work has been prototype driven with a goal of creating usable prototypes - i.e. the prototypes should be easy to deploy and it should be possible to use and test the prototypes daily. Most the prototypes described in this thesis have indeed been deployed and have seen daily use. / <p>Godkänd; 2005; 20061004 (ysko)</p>

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The aim of the study is to contribute to research in the field of maintaining long-term engagingness in chatbots, which is done through rapport building with the help of user and agent specific memory. Recent advances in end-to-end trained neural conversational models (fully functional chit-chat chatbots created by training a neural model) present chatbots that converse well with respect to context understanding with the help of their short-term memory. However, these chatbots do not consider long-term memory, which in turn motivates further research. In this study, short-term memory is developed to allow the chatbot to understand con-text, such as context-based follow-up questions. Long-term memory is developed to re-member information between multiple interactions, such as information about the user and the agent’s own persona/personality. By introducing long-term memory, the chatbot is able to generate long-term memory-based questions, and to refer to the previous conversation, as well as retain a consistent persona. A question answering chatbot and question asking chatbot were initially developed in parallel as individual components and finally integrated into one chatbot system. The question answering chatbot was built in python and consisted of three main components; a generative model using GPT-2, a template structure with a related sentiment memory, and a retrieval structure. The question asking chatbot was built using a framework called Rasa. User tests were performed to primarily measure perceived engagingness and realness. The aim of the user studies was to compare performance between three chatbots; a) individual question asking, b) individual question answering and c) the integrated one. The results show that chatbots perceived as more human-like are not necessarily more engaging conversational partners than chatbots with lower perceived human-likeness. Although, while still not being near human level performance on measures such as consistency and engagingness, the developed chatbots achieved similar scores on these measures to that of chatbots in a related task (Persona-Chat task in ConvAI2). When measuring the effects of long-term memory in question asking, it was found that measures on perceived realness and persona increased when the chatbot asked long-term memory generated questions, referring to the previous interaction with the user.

This report covers a master’s thesis project done at the University Of Utah for the OpenSpace project. OpenSpace is a open-source astronomy visualization software and the thesis focus was to visualize the ever-increasing number of man-made space debris. Two different visualization methods have been used in this thesis. One was a volume rendering and it was evaluated how it works in relation to an orbital trail representation, which was the other method. If the volumetric representation would reduce cluttering, is one of the aspects that will be evaluated, as well as a more open ended exploratory question which is if the volumetric representation can provide any new insights about the data. In short, will a volumetric representation give anything that an orbital representation cannot? A volume rendering can use different types of grids. The thesis evaluates the pros and cons of a cartesian- and spherical grid, as well as the different resolution of the grid and tweaks in the transfer function. An orbital trail representation was previously implemented in OpenSpace (which will be called the individual scene graph node implementation in this report) that had its pros. One con, however, was that it did not scale very well with increasing number of data elements. Visualizing all the data sets containing each trackable piece of space debris simultaneously using this implementation causes the software to slow down significantly. An alternative implementation (which will be called single draw call implementation in this report) was therefore tested in hopes to solve this issue. To see the performance difference, tests were performed where frame time for the whole scene was measured.

I detta kandidatarbete har två medietekniska studenter försökt att ta reda på effektiviteten av att lära sig spelutveckling genom ett digitalt spel som de har utvecklat med två andra medietekniska studenter. För att utveckla detta spelet använde sig av omvärldsanalys, brainstorming, scrumban, moodboards, whiteboxing och lo-fi prototyper för att avsluta på en hi-fi prototyp. Vägen till resultatet har varit väldigt krånglig och ett projekt som redan var stort blev plötsligt svårare när en pandemi svep över världen och studenterna var tvungna att jobba hemifrån med något där kommunikation är det mest väsentliga. Men de fortsatte med att jobba trots omständigheterna. De programmerade, modellerade och designade tills de hade ett digitalt spel som förhoppningsvis nådde målen de hade lagt upp för sig själva. När de kände att spelet var redo för bli testad, skapade de ett formulär för att se om spelet uppnådde det önskade resultatet. När resan är över diskuterar studenterna vad de hade gjort annorlunda om de fick chansen igen.

This report presents the work of our Master´s thesis carried out remotely at the Community Coordinated Modeling Center at the National Aeronautics and Space Administration (NASA) Goddard Space Flight Center. In collaboration with the American Museum of Natural History (AMNH), Linköping University and Predictive Science Inc. The report presents and evaluates an implementation of an interactive 3D visualization of a Solar Particle Event in OpenSpace, an open source astrovisualization software. Data from a model developed by Predictive Science Inc. was used to implement the visualization. The visualization is done by visualizing fluxes of particles as points and utilizing a volumetric data set by applying 2D textures to geometrical shapes. The goal of these visualizations is to help describe the effect of space weather phenomena to the general public. The research conducted is focused on how to visualize a big Solar Particle Event to emphasize or showcase different aspects, such as the radiation exposure close to Earth. The result of the work is an interactive real-time visualization of a Solar Particle Event designed for public outreach. The project culminated in two live streamed events with AMNH, in collaboration with NASA and Predictive Science Inc.

This thesis describes an application-layer framework for managing network connectivity in the 4th-generation wireless systems, which will consist of overlapping heterogeneous networks. If multiple access networks are present, users will have a choice to access the Internet through the “best” available network. The main problem today is that different wireless networks are not particularly integrated and users are in most cases forced to manually interact with the system when switching between networks. The work presented in this thesis addresses this challenge and describes a framework for managing IP mobility while considering competing connection speeds and pricing models. By using an application-layer mobility scheme, called the Resilient Mobile Socket (RMS), the thesis shows how applications can manage handovers and seamlessly migrate data streams between different networks. Moreover, by using a method called Competition based Soft Handovers (CSHM), the thesis demonstrates how handovers can be automatically triggered to the network currently offering the least packet losses and end-to-end delay. Finally, the thesis proposes bandwidth broker to manage network connectivity and share bandwidth effectively between multiple media within an application. As a proof of concept several prototypes have been built into the commercial e-meeting application Marratech Pro. The thesis presents real-life results from exploratory experiments using these prototypes. / <p>Godkänd; 2004; 20060917 (ysko)</p>

This thesis explores the use of wearable computers as mediators for human to human communication. The user of a wearable computer can deliver live video, audio and commentary from a remote location, allowing local participants to experience it and interact with people on the other side. In this way, knowledge and information can be shared over a distance, passing through the owner of the wearable computer who acts as a mediator. One of the main problems of today is that the virtual world offered by wearable computers can become too immersive, thereby distancing its user from interactions in the real world. At the same time, the very same immersion serves to let the user sense the remote participants as being there, accompanying and communicating through the virtual world. The key here is to get the proper balance between the real and the virtual worlds; remote participants should be able to experience a distant location through the user, while the user should similarly experience their company in the virtual world. / <p>Godkänd; 2004; 20060917 (ysko)</p>

This thesis presents research on wearable computers and their usage in communication. The wearable computer is looked upon as a tool for communication between people but also on how it can be used in communication with the environment. A wearable computer has been built with ordinary computer parts and devices available in well-equipped computer stores. This wearable computer is used in this thesis and has both video and audio capabilities and wireless network for communication with people and equipment over distance. The setup has then been used to study the effect of using wearable computer in activities involving communication with people and other equipment. This thesis presents some ways that a wearable computer can be used when considering communication. The user can become a beacon of knowledge sharing the knowledge of people connected to her through the network with people that are collocated with her. She could also become a tool for other people to explore and experience places where they are not located at the moment so called telepresence. It could be said that this is possible with equipment that is available today, but what differences the usage of wearable computer is the possibility to do these activities while still being active in what happens around the user. As the wearable computer should be easy to wear and interact with, the roll as a knowledge beacon or telepresence provider can become almost invisible for the user and other collocated people. To make these rolls as invisible as possible great care must be taken into the interaction between the wearable computer and the user, but also the interaction the user does through the wearable computer with other equipment. When being active as one or both of these rolls the user will mostly be involved in tasks that do not directly involve the wearable computer. When the wearable computer then needs the attention of the user it may have to interrupt the user's current task. This interruption should be done so that the decrease in performance of the user can be kept to a minimum. It is also of equal importance not to only consider the performance but also the experienced stress, which should also be kept to a minimum. A user study is presented in this thesis that explores some of the possible ways to interrupt a wearable computer and analyses what way is preferred when considering both objective and subjective data. In this thesis a novel interaction method called "Eventcasting" is also presented to decrease the time needed to focus on the wearable computer when doing simple tasks with the environment. This is so that interruption on the primary task can be even more minimized and the rolls as a knowledge beacon and telepresence provider can be as invisible as possible. / <p>Godkänd; 2004; 20060916 (ysko)</p>

This thesis report presents a master’s thesis project in Media Technology by two students from Linköping University, Sweden. The project was implemented in collaboration with the Visualization Center C and Linköping University during the spring of 2021 resulting in the creation and development of two spatiotemporal visualizations featuring air traffic data in the OPENSPACE software. One visualization uses live, real-time, data provided by The OpenSky Network through a Representational State Transfer Application Program-ming Interface (REST API). The other visualization uses a static historical data set covering aviation data during the COVID-19 pandemic that is mined from The OpenSky Network. A major challenge during the implementation was handling the large amount of data in a performant manner to avoid a reduced frame rate in the application. To solve this a mul-tithreaded method is used in order to not interrupt the rendering while new data are be-ing fetched to memory. OPENSPACE uses the Application Programming Interface (API) OpenGL to render graphics, thus also enabling a shader pipeline to be utilized. Multiple shaders are used to create the visualizations. The shaders’ purpose and implementation are explained in detail for both visualizations. The live data visualization features aircraft displayed by an anti-aliased trail of past po-sitions while the historical data visualization animates pathlines that represents aircraft with respect to time. The historical data visualization uses multiple Vertex Buffer Objects (VBOs) to render data efficiently and without interruption to allow the animation to play both forward and in reverse. The animation follows the time, time direction, and the speed of which the time plays set by the user in OPENSPACE to play seamlessly. The color of the pathlines are determined by continent to create a clustering effect without any pre-processing or calculations on the Central Processing Unit (CPU). Furthermore, the data can be filtered rapidly and in real-time by using Graphical User Interface (GUI) elements to control the filtering and by performing the actual filtering on the Graphics Processing Unit (GPU). The two visualizations enables user settings via their respective GUI. These settings include changing the color, opacity, and line width to aid in exploration of the data. / <p>Examensarbetet är utfört vid Institutionen för teknik och naturvetenskap (ITN) vid Tekniska fakulteten, Linköpings universitet</p>