This master's thesis is focused on IPTV based on multicast technology. The main aim of this work is to provide detailed analysis of system for watching TV over IP network. It also describes components of IPTV architecture. This master's thesis also discussing about authentication and administration of settopboxes, deals with efficient distribution firmware for STB over multicast and tries to propose and implement portal which provides customer services. It describes the interface development as web service for interconnecting with another management, monitoring and billing information systems. The solution is implemented as a modul into an existing IS of commercial internet service provider.

This study’s main objective is to examine if there is acorrelation between readability and compressibility of Java code. The code readability is important to softwaremaintainability and the comprehension of the code, and thiscan be verified and tested with a range of different metricssuch as B&W, Scalabrino and Dorn’s readability metric.Should there exist a correlation, compressibility could proveto be a simple yet useful readability metric.Data compression is when code or data is encoded usingfewer bits that its original size. There are several algorithmsto do this, and this study works with some of the mostpopular methods. To examine the correlation, we first testedthe different compression algorithms against each other tosee if there was a major difference in size of the resulting file.After that we compared the compressibility between twodifferent types of written code, with previously establisheddifferences in readability.All in all, the source code from a total of 20 popular GitHubprojects were tested with 3 compression algorithms tocompare the differences between the algorithms. For thecompressibility comparisons between code as relating toreadability, a combined total of 104 code snippets weretested, 52 of each compared coding paradigm.Result: For the first test we concluded that there was nosignificant difference between the compression rates of thealgorithms, ending up roughly within 4% or less of eachother on average.The second result reveals a small difference incompressibility between sets of code using reactive Java andobject-oriented Java. These two paradigms are showing adifference in readability according to earlier research, thoughthe difference in compressibility was so small that it wasconsidered negligible. This is due to a lack of variety ofsnippets tested and the difference can largely be attributed tothe small file sizes of some snippets. The smaller filesincreased in size due to the compression adding an“overhead” when a file is compressed. This is morenoticeable on smaller files which this study tested a lot of.In conclusion, the study was unable to indicate a clearconnection between source code readability andcompressibility. Thus, it does not indicate that compressibility is a suitable proxy for readability as of now.This study does however start a conversation on a topicpreviously untouched, and we hope that this study can pointother studies in the right direction. The scope of this researchis too big to be fully explored in this study alone, and westrongly suggest future research on the topic.

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Tato diplomová práce se zabývá metodami pro výběr nejbližší RTP proxy k VoIP klientům s použitím IP anycastu. RTP proxy servery jsou umístěny v síti Internetu a přeposílají RTP data pro VoIP klienty za síťovými překladači adres(NAT). Bez zeměpisně rozmístěných RTP proxy serverů a metod pro nalezení nejbližšího RTP proxy serveru by došlo ke zbytečnému poklesu kvality přenosu médialních dat a velkému zpoždení. Tento dokument navrhuje 4 metody a jejich porovnání s podrobnějšími rozbory metod s využitím DNS resolvování a přímo SIP protokolu. Tento dokument také obsahuje měření chování IP anycastu v porovnání mezi metrikami směrování a metrikami časovými. Nakonec dokumentu je také uvedena implemetace na SIP Express Router platformě.

Computer networks are used in much wider extent than 20 years ago. People use the computer mainly for communication, entertainment and data storage. Information is often stored only in electronic devices and that is why the security of the data is so important. The objective of my thesis is to describe network security problems and their solutions. First chapter deals with the network security, security checks and attacks. It describes procedures used in practise. First part deals with traffic scanning and filtering at various layers of the TCP/IP model. Second part presents the types of proxy and its pros and cons. Network Address Translation (NAT) is a favourite technique of managing IP addresses of inside and outside network which helps to improve the security and lower the costs paid for IP addresses. NAT description, IPSec, VPN and basic attacks are described in this section. The second chapter of the thesis presents set of Perl scripts for network security checking. The purpose of the project is not to check the whole network security. It is designed for contemporary needs of IBM Global Services Delivery Centrum Brno. The first script checks running applications on target object. The aim is to detect services that are not necessary to run or that are not updated. The second one checks the security of the Cisco device configuration. There is a list of rules that has to be kept. The third script inspects the Nokia firewall configuration which is on the border of IBM network. If some of the rule is broken, it shows the command that has to be proceeded at the particular device. The output of the first and the second script is an HTML file. The third script uses the command line for the final report. The last part of this chapter gives advice to configure Cisco devices. It is a list of security recommendations that can be used by configuring e.g. routers. The appendix presents two laboratory exercises. The aim is to give students an opportunity to learn something about programs and technologies which are used in practise by IT experts to check the weaknesses of their networks.

Scaling of TLM (Transaction Level Modeling) simulations for performance is difficult. In this project I will go through several causes of poor performance. This paper describes several simulation engines that use SystemC that are connected so they together simulate next generation radio base station. It also describes how to build a virtual network in, for security reasons, constrained environment where both virtual and physical equipment can connect the simulated target. Furthermore, it describes how to use the virtual network to improve the overall performance of the simulation. It is shown how the virtual network is used to distribute the simulation and offloading the simulated target to accomplish the performance goal. / Det är svårt att skala upp en simulering baserad på TLM (Transaction Level Modeling). I detta projekt kommer jag att gå igenom flera orsaker till dålig prestanda. Denna rapport beskriver flera olika simuleringsmotorer som använder SystemC och som är kopplade så att de tillsammans simulerar nästa generation radiobasstationer. Här beskrivs också hur man bygger ett virtuellt nätverk som hanterar begränsningar som finns av säkerhetsskäl, och trots detta kan koppla ihop virtuell och fysisk utrustning till det simulerade målsystemet. Dessutom anges hur detta virtuella nät används för att förbättra den övergripande prestandan i simuleringen. Detta görs genom att utnyttja det virtuella nätet för att distribuera simuleringen och avlasta målsystemet.

TV-apparater och kringutrustningar är numera ofta Internetanslutna och har inbyggda webbläsare som fungerar som en plattform för HTML5- applikationer med JavaScript, vilket har lett till att utbudet av applikat- ioner som finns tillgängliga på dessa plattformar ökat explosivt de senaste åren. Tyvärr lider dock många av dålig prestanda med avseende på dataö- verföring och användargränssnittet upplevs ofta som segt eftersom hård- varan inte kan mäta sig med en modern dator. Det här examensarbetet undersöker vad som kan optimeras på närverkssidan. Två metoder för optimering har utvärderats - cache och komprimering av data från både applikationspaket och externa källor till slutanvändaren. Mätningar har gjorts på en befintlig TV-applikation för att identifiera var det finns störst utrymme för förbättringsåtgärder. Jämförelser mellan olika lösningar visar att vissa metoder kan snabba upp särskilda processer betydligt, me- dan andra metoder t.o.m. kan ha en negativ effekt. De lösningar som visat bäst resultat med avseende på snabbhet har implementerats i den befint- liga applikationen. Hänsyn till lämplighet av drift och underhåll av lös- ningarna har också tagits. Resultatet av dessa optimeringar visar att det med relativt enkla metoder går att avsevärt förbättra användarupplevelsen för Internetanslutna TV- applikationer, bl.a. har uppstartstiden visats kunna minskas med ca 80 % i de tester som utförts. / As televisions and peripheral devices nowadays often are Internet con- nected and has built-in web browsers that work as a platform for HTML5 applications running JavaScript, the range of applications available on these platforms has increased drastically. However, many suffer from poor performance in terms of data transfer and the user interface is often experienced as slow since the hardware cannot compare to a modern desktop computer. This thesis examines what can be optimized on the networking side. Two optimization methods have been evaluated - caching and compression of data of both the application package and external resources to the end user. Measurements have been made on an existing TV application to identify which parts have biggest room for im- provements. Comparisons between the various solutions show that some methods can speed up specific processes significantly, while other methods even may have a negative effect. The solutions that have shown the best results based on the speed improvements have been implemen- ted in the existing application. Consideration of the suitability of the maintenance of the solutions were also taken. The results of these optimizations show that relatively simple methods can significantly improve the user experience for an connected TV appli- cations. For instance, a reduction of about 80 % of the startup time has been measured in the performed tests.

Mobile web browsers of today have many of the same capabilities as their desktop counterparts. However, among the capabilities they lack is a way for web applications to interact with local devices. While today’s mobile phones commonly include GPS receivers and digital cameras, these local devices are currently not accessible from within the browser. The only means of utilizing these devices is by using standalone applications, but such applications lack the versatility of web browsers. If a mobile browser could utilize these local devices, then a mobile application could run within the browser, thus avoiding the need for specialized client software. This thesis suggests an approach for adding such capabilities to mobile browsers. In the proposed method, scripted access to local device functionality is facilitated by a local Java application. This application acts as a proxy server and allows the browser to call methods exposed by the local Java APIs. Both the benefits and some security concerns of this approach are examined. The benefits are further highlighted through two example web applications which utilize local devices. / I dagens mobila webbläsare återfinns det mesta av funktionaliteten från webbläsare för datorer. Det som dock fortfarande saknas är möjligheten för webbapplikationer att komma åt lokala telefonfunktioner. Dagens mobiltelefoner är ofta utrustade med GPS-mottagare och digitalkameror, men dessa kan för närvarande ej nås från webbläsaren. Det enda sättet att utnyttja dessa inbyggda funktioner är genom separata applikationer, men sådana applikationer är inte lika mångsidiga som webbläsare. Om en mobil webbläsare kunde utnyttja de inbyggda funktionerna, så skulle en mobil applikation kunna köras i webbläsaren istället för att ha separat klientprogramvara. Det här examensarbetet föreslår ett sätt att ge denna möjlighet till mobila webbläsare. I den föreslagna metoden används en lokal Java-applikation för att ge tillgång till inbyggda funktioner via skript. Denna applikation fungerar som en proxy-server och låter webbläsaren anropa metoder exponerade av lokala Java-API. Både fördelar och några säkerhetsproblem med den här lösningen undersöks. Fördelarna visas ytterligare genom två exempel på webbapplikationer som utnyttjar inbyggda telefonfunktioner.

Polygonal terrain underlain by ice wedges (IWs) are a widespread feature in continuous permafrost and make up 20-35%vol of the ground ice in the upper few meters of permafrost. Despite the numerous contemporary studies examining factors that control ice wedge cracking, development and degradation, relatively few have explored ice wedge activity in relation with past climate and vegetation conditions. In the Eureka Sound region, ice wedge polygons dominate the permafrost terrain. Their degradation has started to occur, leading to growth of thaw slumps. The objective of this study is twofold, the principal objective is to investigate the timing of ice wedge activity in the Eureka Sound region using the ¹⁴CDOC dates. The second objective is to evaluate the use of ice wedges as paleotemperature proxies. In July 2018, four ice wedges were sampled at 3-4 depths with each core sample being ~1m in length. In the following summer, eight ice wedges were sampled from the surface, 3-5 core samples were extracted per wedge. Active layer and snow samples were also recovered. Laboratory analyses on the ice wedge samples includes dissolved organic carbon content (DOC) and δ¹³CDOC, radiocarbon dating of DOC, geochemical concentration, and stable water isotopes. The DOC and geochemical results show that snowmelt is the main moisture source for ice wedges in the Eureka Sound region with a minor contribution of leached surface organics. The age (¹⁴CDOC) and size of the studied ice wedges were compared against a cracking occurrence model developed by Mackay (1974), these ice wedges align well with this model and suggest that ice wedge growth is non-linear. Ice wedges in the Eureka Sound region were active during the early to late Holocene (9-2.5 ka). The majority of the activity occurred in the later stage of the early Holocene following regional deglaciation and marine regression. ¹⁴CDOC, high resolution δ¹⁸O and D-excess suggests the occurrence of peripheral cracking in both large and small ice wedges. Rayleigh-type isotopic fractionation was found to occur with depth. As well, post depositional isotopic modification of snow and snowmelt accounts for up to a 4‰ difference of δ18O in surface ice wedge samples. δ¹³CDOC of surface ice wedge samples suggest a habitat transition during the late Holocene from dry meadows to polygonal terrain and the geochemical composition of ice wedges closely reflects that of glacial ice core records.

Solar ultraviolet (UV) radiation ionizes the neutral components in the atmosphere, which is partly responsible for the formation of the ionosphere, and contributes to heating of the atmosphere. Solar flares change the solar spectrum at times by several orders of magnitude. These changes modify the Earth's upper atmosphere, causing problems to communication systems and space operations, such as increased satellite drag. Unfortunately, solar UV measurements are limited since they can only be observed with space-based sensors. In order to work around this limitation, the solar radio emissions at a wavelength of 10.7 cm have been used as a proxy for the solar UV radiation. These measurements, known as the F10.7 index, are a snapshot of the solar activity at the time they are taken and do not capture the changes that occur throughout the day, such as flares. In order to capture this daily variation, we used 1-second cadence solar radio data and compared it to solar UV measurements taken once per orbit by the TIMED satellite. We found significant correlations between some radio frequencies and different UV wavelengths during quiet times. These correlations changed in terms of radio frequency and UV wavelength during solar flares.