Rigorous methods for design and implementation of safety critical real-time systems are vital to avoid loss of human lives and/or severe economic losses. Unfortunately, many of these systems are designed and evaluated using ad-hoc techniques. There are, on the other hand, relatively well developed scientific theories for modeling and analysis of timing and reliability. These theories are, however, only very slowly being introduced in industrial development. Important reasons for this are the simplifying model assumptions and lack of appropriate tools for timing analysis. This thesis presents two new methods aimed to narrow the gap between scientific results and industrial practice in evaluation and design of real-time systems. The first contribution is a method that from execution time measurements on the target system can derive worst-case execution time estimates of programs. Such estimates are essential when verifying if a system fulfills its timing requirements. The second contribution is a simulation based technique that can be used to evaluate timing aspects of distributed real-time systems, as well as calculating reliability estimates of these systems. Such estimates are essential in determining if a system meets its requirements sufficiently well. Compared to proposed analytical methods for execution time analysis and schedulability analysis, the starting point for both these methods are real target systems, rather than an abstract model with limited correspondance to reality. The presented initial case-studies give clear evidence that the proposed methods have potential of being both applicable and useful.

Systemövervakning har blivit en stor del av företags IT-strukturer eftersom företag förlitar sig mer och mer på en välfungerande och högt presterande IT- struktur. När det sker problem i företags IT-strukturer så krävs det att de löses under relativt kort tid. För att hitta problemet så krävs det en mängd olika system som skall underlätta arbetet för människor som arbetar med systemövervakning och underhåll av IT-strukturer. För att tolka och bearbeta all den information som en IT-struktur tillhandahåller så krävs det system vars uppgift är att hjälpa människor att tolka den enorma mängd data en IT-struktur genererar. Denna rapport ger en beskrivning över hur arbetet för en systemadministratör kan förenklas med hjälp av ett integrerat övervakningssystem. Stora delar av rapporten kommer fokusera på vilken metod och protokoll som kan användas för att hämta information från olika övervakningssystem och även förslag på hur informationen kan presenteras för användaren.

Det här examensarbetet utvärderar utvecklingsverktyget Gideros som används för att tillverka spelapplikationer. För att utvärdera har en app tillverkats och Gideros har jämförts mot andra spelutvecklingsverktyg.

Near Field Communication (NFC) is a short range wireless communication technology that enables data exchange between devices. NFC is used in many different areas, from subway tickets to authentication systems. This paper presents possible security threats to Near Field Communication and documented attacks that have been used to target various NFC protocols. Weaknesses in different NFC protocols will be presented and suggestions on how to counter certain weaknesses will be discussed. This survey will be valuable for companies interested in protecting their data when using or planning to use NFC systems.

As information can be sent via various mediums through different channels,  visual or vocal communication can also be carried out though various channels such as public switched networks (PSTN) and packet based switched systems which are commonly known as voice over Internet protocol (VOIP). This particular study emphasizes on voice over Internet protocol and its various aspects.   Codec is the most important aspect in VOIP communication there is variety of codecs available. In order to have right quality of voice the right codec must be selected. There are various other factors such as bandwidth and right technical infrastructures which are also present and which must be addressed in order to have a better quality of voice over VOIP.   Mostly, VOIP is used in companies where a huge volume of voice calls is needed, especially in call centers which deal in offshore sales and support projects. The main factor which make companies and other users interested in  VOIP is the financial aspect as, VOIP cuts costs significantly. Every mode which may be utilised for voice communication has its own advantages and disadvantages so user can chose the mode of communication according to what is required.   In order to provide the financial and technical advantages of VOIP, various previous studies have been studied, information has been collected from different call centers and a network is simulated using OPNET MODELLER in order to evaluate the performance of VOIP codec as the codec is basically coder as well as decoder, hence it is the basic aspect in order to have a better quality of services (QOS) and quality of voice (QOV).

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Detta dokument behandlar ett kandidatarbete gjort av sju datateknikstudenter från Tekniska högskolan vid Linköpings universitet. Arbetet gick ut på att utveckla en webbapplikation för att visa bilder. Målet med webbapplikationen var inledningsvis vagt, den skulle visa bilder, ha någon metod för att ta reda på vilka bilder användaren gillade och sedan basera vilka bilder som skulle visas nästa gång på vilka som hade gillats. Dokumentet innehåller också ett kapitel om de erfarenheter och lärdomar gruppen har fått från projektet. Det innehåller även ett appendix med kapitel skrivna av gruppens medlemmar som behandlar olika ämnen relevanta till arbetet.

In a highly mobile and networked society the need to download large amounts of data on a mobile network is inevitable. This thesis analyzes the predictability of download speeds in mobile networks to be able to schedule downloads while in areas with high download speeds. This decreases the download time and thus the energy wasted downloading. The data analyzed is from Bredbandskollen. We find that in areas of 200 x 200 meters the download speed is easiest to predict due to a low covariance. We also find that areas with high average download speed are more likely to have neighboring areas with similar download speed than areas with low average download speed, making it easier to predict the download speed when moving between such locations. Finally, we show paths in urban areas where a user can move long distances and experience similar download speeds.

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