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Multimedia conferences held using services provided by clouds owned by third party companies are becoming increasingly popular. While using such services, end users will want to keep their audio/video data private when they pass through the servers situated in the cloud. Application of SRTP (Secure Real-time Transport Protocol) in such use cases fail to provide the desired privacy because it leads to sharing the master keys for encryption and authentication of the media content with the semi trusted media servers of the cloud. As a solution, modifications of SRTP are proposed in this thesis with the result of redesigning the security mechanisms of RTP header extensions and RTCP packets by separating the cryptographic contexts and keying materials for protecting end-to-end sensitive data. A couple of design choices for key management through DTLS-SRTP for Cloud conferencingare also proposed. Moreover, analysis of existing solutions for modifying SRTP packets for cloud conferences have also been carried out in this project. The solutions are found by studying related protocols, understating the problems and analyzing current solutions if there were any. The proposed solutions show different alternatives to solve a specific problem and their tradeoffs in terms of complexity and compatibility with current standards.

Distributed generation is transforming the power system grid to decentralized system where separate units like wind power generators or solar panel shall coexist and operate in tandem in order to supplement each other and make one extensive system as a whole so called smart grid. It is utmost important to have a control ability over such units not only on a field level but on a system level as well. To be able to communicate with numerous devices and maintain interoperability universal standard is a must. Therefore, one of the core standards relevant to smart grids is IEC 61850 – Power Utility Automation which comes into assistance and tackles aforementioned challenges. This project uses IEC61850 architecture to implement client/server windows applications for on-load tap changer remote control. The proposed solution and designed applications are tested together with a real time simulator where simple power system is modelled to emulate the system response to control signals in a real time. In this way, the implemented applications can be tried and assessed as if performing in real environment. Consequently, a user of the client application is able to remotely control voltage on the power transformer's secondary side and manipulate the switching equipment simulated in the model. / Distribuerad generation håller på att förändra transmissionsnätet till decentraliserat system där separata enheter som vindkraftverk eller solpanel skall samexistera och fungera tillsammans för att komplettera varandra och att göra ett omfattande system som helhet så kallade smarta elnät. Det är ytterst viktigt att ha en kontroll förmåga över sådana enheter inte bara på ett fältnivå utan även på systemnivå. För att kunna kommunicera med många enheter och bibehålla interoperabiliten som universell standard är ett måste. En av de grundläggande normer som är relevanta för smarta nät är IEC 61850 - Skydd & Automation, som kommer in i bistånd och möter ovan nämnda utmaningar. Detta projekt använder IEC61850-struktur för att implementera klient/server windows applikation för lindningskopplarens fjärrkontroll. Den föreslagna lösningen och utformade applikationer testas tillsammans med en realtidssimulator där enkelt kraftsystem modelleras för att emulera systemets svar på de givna styrsignalerna i realtid. På detta sätt kan de implementerade programmen prövas och bedömas hur de utföras i verklig miljö. Följaktligen kan användare av klientapplikationen fjärrstyra spänningen på transformatorns sekundärsida och manipulera ställverk som simuleras i modellen.

<p>As energy costs and energy used by server farms increase, so does the desire to implement energy-aware policies. Although under some cost functions, optimal policies for single as well as multiple server systems are known, large gaps in theoretical knowledge are present in the field. Specifically, there exists many widely used and non-trivial cost functions, where the corresponding optimal policy remains unknown. This work presents and leverages a model which allows for the exact analysis of these optimal policies with considerable generality, for on/off single server systems under a broad range of cost functions that are based on expected response time, energy usage and switching costs. Furthermore, from the results derived in the analysis, several applications and implications are presented and discussed. This includes the determination of routing probabilities to show a range of non-trivial optimal routing probabilities and server configurations when energy concerns are a factor.</p> / Master of Applied Science (MASc)

As developments in wireless ad hoc networks continue, there is an increasing expectation with regard to supporting content-rich multimedia communications (e.g., video) in such networks, in addition to simple data communications. The recent advances in multiple description (MD) video coding have made it highly suitable for multimedia applications in such networks. In this thesis, we study three important problems regarding multiple description video communications in wireless ad hoc networks. They are multipath routing for MD video, MD video multicast, and joint routing and server selection for MD video in wireless ad hoc networks. In multipath routing for MD video problem, we follow an applicationcentric cross-layer approach and formulate an optimal routing problem that minimizes the application layer video distortion. We show that the optimization problem has a highly complex objective function and an exact analytic solution is not obtainable. However, we find that a metaheuristic approach such as Genetic Algorithms (GAs) is eminently effective in addressing this type of complex cross-layer optimization problems. We provide a detailed solution procedure for the GA-based approach, as well as a tight lower bound for video distortion. We use numerical results to compare this approach to several other approaches and demonstrate its superior performance. In MD video multicast problem, we take the similar application-centric, cross-layer approach as in the multipath routing problem. We propose an MD video multicast scheme where multiple source trees are used. Furthermore, each video description is coded into multiple layers in order to cope with diversity in wireless link bandwidths. Based on this multicast model, we formulate the multicast routing as a combinatorial optimization problem and apply Genetic Algorithm (GA)-based metaheuristic procedure to solove this problem. Performance comparisons with existing approaches show significant gains for a wide range of network operating conditions. In the last problem, we study the important problem of joint routing and server selection for MD video in ad hoc networks. We formulate the task as a combinatorial optimization problem and present tight lower and upper bounds for the achievable distortion. The upper bound also provides a feasible solution to the formulated problem. Our extensive numerical results show that the bounds are very close to each other for all the cases studied, indicating the near-global optimality of the derived upper bounding solution. Moreover, we observe significant gains in video quality achieved by the proposed approach over existing server selection schemes. This justifies the importance of jointly considering routing and server selection for optimal MD video streaming in wireless ad hoc networks. / Master of Science

With the introduction of partially reconfigurable FPGAs, we are now able to perform dynamic changes to hardware running on an FPGA without halting the operation of the design. Module based partial reconfiguration allows the hardware designer to create multiple hardware modules that perform different tasks and swap them in and out of designated dynamic regions on an FPGA. However, the current mainstream partial reconfiguration flow provides a limited and inefficient approach that requires a strict set of guidelines to be met. This thesis introduces BitMaT, a tool that provides the low-level bitstream manipulation as a member tool of an alternative, automated, modular partial reconfiguration flow. / Master of Science

Advances in information technology are driving massive improvement to the education industry. The ubiquity of mobile devices has triggered a shift in the delivery of educational content. More lessons in a wide range of subjects are being disseminated by allowing students to access digital materials through mobile devices. One of the key materials is digital-based educational games. These games merge education with digital games to maximize engagement while somewhat obfuscating the learning process. The effectiveness is generally measured by assessments, either after or during gameplay, in the form of quizzes, data dumps, and/or manual analyses. Valuable gameplay information lost during the student's play sessions. This gameplay data provides educators and researchers with specific gameplay actions students perform in order to arrive at a solution, not just the correctness of the solution. This problem illustrates a need for a tool, enabling educators and players to quickly analyze gameplay data. in conjunction with correctness in an unobtrusive manner while the student is playing the game. This thesis describes a client-server software architecture that enables the collection of game-based data during gameplay. We created a collection of web services that enables games to transmit game-data for analysis. Additionally, the web application provides players with a portal to login and view various visualization of the captured data. Lastly, we created a game called "Taffy Town", a mathematics-based game that requires the player to manipulate taffy pieces in order to solve various fractions. Taffy Town transmits students' taffy transformations along with correctness to the web application. Students are able to view several dynamically created visualizations from the data sent by Taffy Town. Researchers are able to log in to the web application and see the same visualizations, however, aggregated across all Taffy Town players. This end-to-end mapping of problems, actions, and results will enable researchers, pedagogists, and teachers to improve the effectiveness of educational games. / Master of Science

This master's project deals with location based systems and their application in information distribution. The work discuss kinds of getting actual location. Then it focuses on problems of developing applications and description of Microsoft technologies for mobile devices. Based on obtained theoretical information we present design, implementation and testing of our own location based system.

This master's thesis deals with design of security infrastructure for electronic archive. In theoretical part is disscus about technical resources which are based on security services and protocols and methods which are used for protection. On basics of theoretical part is designed model of security infrastructure and it is built in laboratory. Model of security infrastructure is based on Open Source Software and as safety storages for private user authentication data are used cryptographic USB tokens. This master's thesis includes design and construction of real infrastructure of secured electronic archive. In each part of master's thesis is put main emphases on security and clear explanation from the beginning of desing of model of security infrastructure for electronic archive to finish of construction.

Informationen für URZ-Nutzer, in dieser Ausgabe speziell der 'Jahresrückblick 2010' - eine Übersicht zur Entwicklung der zentralen IT-Dienste und der IT-Infrastruktur der TU Chemnitz.:Jahresrückblick 2010 - Der URZ-Beirat - Projekte des Jahres 2010 - Lernmanagement und E-Learning an der TU Chemnitz - Entwicklung der Voice-Over-IP-Dienste - Campusnetz-Infrastruktur und Netzdienste - Koordinierung und Entwicklung zentraler Webangebote (Internet-AG) - Nutzung öffentlicher Rechner - Administrationsdienste - Virtual Private Server Hosting (VPSH) - Server Housing - IT-Dienste für die Zentrale Universitätsverwaltung - IT-Dienste für Universitätsbibliothek und Patentinformationszentrum - Speicherdienste - User-Management und Accounting - Software-Dienste - Hardware-Dienste - Ticketsystem OTRS - Aus- und Weiterbildung Kurzinformationen Software-News