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Dissertations / Theses on the topic 'ISP network'
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Sandford, Peter. "Inferring malicious network events in commercial ISP networks using traffic summarisation." Thesis, Loughborough University, 2012. https://dspace.lboro.ac.uk/2134/9580.
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With the recent increases in bandwidth available to home users, traffic rates for commercial national networks have also been increasing rapidly. This presents a problem for any network monitoring tool as the traffic rate they are expected to monitor is rising on a monthly basis. Security within these networks is para- mount as they are now an accepted home of trade and commerce. Core networks have been demonstrably and repeatedly open to attack; these events have had significant material costs to high profile targets. Network monitoring is an important part of network security, providing in- formation about potential security breaches and in understanding their impact. Monitoring at high data rates is a significant problem; both in terms of processing the information at line rates, and in terms of presenting the relevant information to the appropriate persons or systems. This thesis suggests that the use of summary statistics, gathered over a num- ber of packets, is a sensible and effective way of coping with high data rates. A methodology for discovering which metrics are appropriate for classifying signi- ficant network events using statistical summaries is presented. It is shown that the statistical measures found with this methodology can be used effectively as a metric for defining periods of significant anomaly, and further classifying these anomalies as legitimate or otherwise. In a laboratory environment, these metrics were used to detect DoS traffic representing as little as 0.1% of the overall network traffic. The metrics discovered were then analysed to demonstrate that they are ap- propriate and rational metrics for the detection of network level anomalies. These metrics were shown to have distinctive characteristics during DoS by the analysis of live network observations taken during DoS events. This work was implemented and operated within a live system, at multiple sites within the core of a commercial ISP network. The statistical summaries are generated at city based points of presence and gathered centrally to allow for spacial and topological correlation of security events. The architecture chosen was shown to be exible in its application. The system was used to detect the level of VoIP traffic present on the network through the implementation of packet size distribution analysis in a multi-gigabit environment. It was also used to detect unsolicited SMTP generators injecting messages into the core. ii Monitoring in a commercial network environment is subject to data protec- tion legislation. Accordingly the system presented processed only network and transport layer headers, all other data being discarded at the capture interface. The system described in this thesis was operational for a period of 6 months, during which a set of over 140 network anomalies, both malicious and benign were observed over a range of localities. The system design, example anomalies and metric analysis form the majority of this thesis.
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Gao, Hongyan. "Network and I/O Characteristics of ISP Mail Servers." University of Cincinnati / OhioLINK, 2002. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1013197957.
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Doležal, Martin. "Implementace vybrané technologie pro ISP." Master's thesis, Vysoké učení technické v Brně. Fakulta podnikatelská, 2016. http://www.nusl.cz/ntk/nusl-234777.
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The thesis focuses on implementation of selected technology within the company CPU-Kocourek, s.r.o, which provides varied internet services. Based on the theoretical part and the analysis of the current situation are proposed solutions suitable for the management of access network provider. The proposal part contains selection of the best proposal and its implementation into the routine mode of operation.
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Důbrava, Marek. "Řízení datového toku v ISP síti." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2016. http://www.nusl.cz/ntk/nusl-242049.
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The thesis focuses on the control of data flow in networks of Internet service providers. The problem of aggregation and related overload network elements are shown. Theoretical section describes the standardized methods for managing data flow. The parameters associated with managing data flow are described for devices selected devices. The thesis displays measurements depicting to which extent the ECN algorithm occurs in practice. In the thesis is theoretically described HTB program, which is complemented by a newly described algorithm. The new algorithm is implemented into the program and tested on a real network ISP.
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Cheema, Ansar Zaman, and Imran Ullah Saqib. "Collaborating ISPs Supporting Various Real-Time Services." Thesis, Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:hh:diva-4902.
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These days, internet service providers (ISPs) face the challenge about how to increase profitability while hey must ensure a good quality service at the same time and scale up their network. The study involves previous research papers. On the bases of those papers,the comparison is made between different alternatives. The purpose on this study is to find a solution that combines different methods and configurations about how several ISPs could cooperate. Its implementation includes how different ISPs can configure their networks to cooperate on service provision supporting various real-time services.
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Kmoníček, Tomáš. "Aplikace pro monitorování a správu sítě pro ISP." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2009. http://www.nusl.cz/ntk/nusl-217877.
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The objective of this master‘s thesis is to develop an ISP application for service monitoring and management. A fully functioning monitoring software has been developed that allows the administrator to check round-trip time and packet loss in the entire network. Another function of the application is obtaining information from network devices by the SNMP protocol (e.g. packet and byte count etc.). The software uses this information to create graphs per hour, day, week or year. All graphs and statistics are visualised on the administration website. For the purpose of client administration, a client database has been developed. This part of the application enables the management of payments, IP addresses, contacts etc. Both parts of the web pages have been developed by using mod_python and AJAX, making the application similar to standard desktop applications. The testing application has been developed by using Python and the entire application has been designed for modules, which can be later used for the development of other functions.
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Chen, Sheng. "Future development trends of optical transport network infrastructure an infrastructural framework for metropolitan-based optical transport networks : a field test of a Chinese ISP and a case study of a Chinese electrical power company /." Access electronically, 2006. http://www.library.uow.edu.au/adt-NWU/public/adt-NWU20070822.115714/index.html.
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Cao, Wei Qiu. "A new Content Distribution Network architecture - PlentyCast." Thesis, KTH, Mikroelektronik och informationsteknik, IMIT, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-92592.
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Content Distribution Networks have existed for some years. They involve the following problem domains and have attracted attention both in academic research and industry: content replica placement, content location and routing, swarm intelligence, and overlay network self-organization for this type of distributed system. In this project, we propose a novel Content Distribution Network architecture – PlentyCast. This study focuses on improving access latency, network scalability, high content availability, low bandwidth consumption, and improving infrastructure performance for Content Distribution Networks. Outstanding problems such as: Flash crowd, DoS, and difficulty of traffic engineering due to Peer-to-Peer are addressed.Mediadistributionsnätverk har funnits några år. De har fått uppmärksamhet i både akademisk forskning och i industrin och kännetecknas av följande frågor: placering av innehållskopior, lokalisering av innehåll och routing, svärm intelligens, överlagrade nätverks självorganisering för denna typ av fördelade system. I denna rapport studeras en ny nätverksarkitektur för innehållsfördelning - PlentyCast. Denna studie fokuserar på tillgångslatens, nätverksskalbarhet, hög innehållstillgång, låg bandbreddskonsumtion, och förbättrad infrastrukturprestanda för Innehållsfördelningsnätverk.
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Abrar, Mirza Kashif, and Imran Pervaiz. "Reliability and Load Handling Problem in Internet Service Provider’s Network." Thesis, Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:hh:diva-4228.
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This thesis puts forward a new solution to provide the reliable network to the Internet Service Provider (ISP). This study mainly focuses on the ISPs network to provide reliability and the load balancing. It offers a guide line for the best reliable solution to the ISPs, individual organizations or other types of service providers which are engaged in providing reliable communications to their subscribers. These reliable services may be real time communications which include weather forecasts, tracking systems, online Internet protocol TV (IPTV) programs and many other ISPs services which are totally depend on the reliable network.
With the appearance and expansion of Internet subscribers all over the world, ISPs services are becoming more popular. The rapid increase of connection-demand and highly traffic network is the main reason behind the need to scale reliable network. To offer better solutions, a new theoretical and practical approach should be considered that can cover the reliable network.
The suggested network structure monitors the links, spreads the network traffic with multiple devices and takes a backup (redundant) link automatically when changes occur in the network topology. In order to support the redundancy, load balancing and reduce the failover time, the hot standby routing protocol (HSRP) is implemented on the suggested network. As we have analyzed that in any network, scalability bringing to raised the network traffic broadcast issue. Broadcast storms can be prevented by setting threshold values of traffic-filters. The threshold level helps to control broadcast traffic in networks.
With regard to suggested solutions, it is necessary to observe the limitations and advantages of the recommended reliable network structure. Therefore, this research will include the advantages and limitations of the techniques used to offer ISP services such as scalability, security and IPv6.
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Parolek, Pavel. "Bezpečnost bezdrátové sítě poskytovatele internetových služeb." Master's thesis, Vysoké učení technické v Brně. Fakulta podnikatelská, 2013. http://www.nusl.cz/ntk/nusl-223791.
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This thesis analyzes the wireless network security of the Internet service provider company Net-Connect s.r.o. It identifies its weak points and suggests measures that lead to the increase of the wireless network security.
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Patriksson, Andreas. "Net Neutrality - Do We Care? : A study regarding Swedish consumers' point-of-view upon Net Neutrality." Thesis, KTH, Skolan för datavetenskap och kommunikation (CSC), 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-204467.
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Net Neutrality implicates that all data being transmitted online is treated equal by Internet Service Providers. In 2016, the public debate regarding Net Neutrality in Sweden started growing as two major Mobile Network Operators were investigated by the Swedish Post and Telecom Authority for violation of European Union Net Neutrality regulations. Several studies have been conducted regarding Net Neutrality, most of them written in a legal, financial or technological perspective. This study takes another direction, aimed at understanding the consumer’s point of view regarding Net Neutrality. This study investigates whether or not consumers are aware of the subject and if so, how they value it. To measure this, an online survey was constructed, containing a total of 12 questions and statements. 77 people participated in the survey and out of these, 10 people participated in qualitative follow-up interviews. The interviews were semi-structured and individually designed according to each participant’s answers in the survey. This was done in order to gain a deeper understanding of the consumer’s reasoning while answering the survey. The results show that consumers lack knowledge regarding Net Neutrality. A major part of the consumers had not heard of the term or did not know the meaning of it, making it hard to determine whether or not the consumers value NN. However, when given a more concrete example of the implications of Internet Traffic Management from ISPs, the participants had a better understanding of what kind of implications NN could have on their Internet usage. They valued the implications of Net Neutrality, even though they did not know the theory of the term itself. The study also revealed that consumers have a big confidence in National Regulatory Authorities when it comes to looking after the openness of the Internet. Therefore, it is likely that National Regulatory Authorities must inform and educate consumers in the matter of Net Neutrality for them to value it and see its long-term implications.Nätneutralitet innebär kortfattat att all data som skickas över Internet ska behandlas likvärdigt utav Internetleverantörer (ISP). Under 2016 växte debatten kring nätneutralitet i Sverige då två stycken mobiloperatörer utreddes utav Post- och Telestyrelsen. Båda dessa mobiloperatörer lanserade kampanjer till sina kunder som ansågs strida mot EU:s förordning 2015/2120 rörande nätneutralitet. Ett antal studier har redan gjorts på ämnet nätneutralitet, dock har de flesta haft en infallsvinkel där man tittat på juridiska, finansiella eller tekniska perspektiv. Den här studien har en annan infallsvinkel och riktar sig istället mot konsumenters syn på nätneutralitet. Den ämnar undersöka huruvida konsumenter känner till begreppet nätneutralitet och om de gör det, hur värderar de konceptet? För att undersöka detta konstruerades en online-enkät, innehållandes 12 frågor. 77 personer deltog i enkäten och utav dessa så deltog 10 personer i uppföljande, kvalitativa intervjuer. Intervjuerna var semi-strukturerade och individuella med frågor baserade på individens svar i enkäten. Dessa intervjuer var till för att ge en fördjupad förståelse av konsumenternas syn på nätneutralitet och deras resonemang kring svaren under enkäten. Resultaten visar att konsumenter, deltagande i den här studien, har låg kunskap kring nätneutralitet. Majoriteten utav deltagarna hade inte hört termen eller kände inte till dess mening, vilket gjorde det svårt att dra några slutsatser kring huruvida konsumenterna värderar konceptet. Men när konsumenterna fick ett mer konkret exempel på hur Internetleverantörers datahantering påverkar kundernas Internetanvändande så tycktes konsumenterna förstå vilka implikationer nätneutralitet kan ha på deras eget Internetanvändande. De tycktes således värdera innebörden av nätneutralitet, även om de inte förstod teorin kring konceptet. Studien påvisade också att konsumenter har en stor tilltro till vederbörande myndighet, Post- och Telestyrelsen här i Sverige, när det gäller att se efter Internets öppenhet och mångfald. Det är därför troligt att Post- och Telestyrelsen kommer att behöva informera och utbilda konsumenter rörande nätneutralitet för att få konsumenter att se värdet av och de långsiktiga implikationerna utav det.
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Xiong, Ziyi. "Socio-economic Impact of Fiber to the Home in Sweden." Thesis, KTH, Kommunikationssystem, CoS, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-118777.
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Fiber-to-the-Home (FTTH) has been talked about since the introduction of fiberin the 1970s. It is nowadays shaping up to be the foundation of our newdigital society, bringing economic prosperity and a multitude of business,social, and entertainment opportunities to its users. The increased consumerdemand for high-speed network accessibility is being taken more and moreseriously and a fiber-based network is able to cope with these growing demandsdue to its wide bandwidth and reliability. Today there is a practical need forquantitative analysis regarding the socio-economic impacts of fiber-basedaccess networks. This analysis could be used as an indicator/reference for allthe stakeholder entities as they consider future investments anddevelopments. Sweden is a suitable target country for this analysis since ithas adopted fiber for some years and the benefits that FTTH has brought seemto already be tangible. The primary value of this thesis lies ininvestigation of its quantified evidence of the socio-economic impacts of FTTHdeployment in Sweden. This has been achieved based on data from the SwedishPost and Telecommunications Authority (PTS), Statistics Sweden (SCB), previousrelated studies, and information collected on-line from operators involved inthe fiber market, along with empirical analysis based on multivariateregression models. The results of the study show that fiber penetrationhas had a significant impact on the population’s evolution, specially the netamount of migration into a municipality, which indicates the attractiveness ofmunicipalities per se. It is therefore reasonable to suggest that localgovernment and local authorities take fiber deployment into consideration, ifthey want to attract people to stay for further local development. The studyalso analyzed the competition in fiber-based open networks and the prices ofsubscribing for 10/10 Mbps symmetrical Internet Service. Study findingsrevealed that networks with multiple competing service providers have a widerrange of services and a lower price: the more ISPs competing in a fibernetwork, the lower consumer prices. Specifically, for each new serviceprovider present in the network, there will be 5 SEK per month decrease of theaverage price of the Internet services, and an approximately 7 SEK per monthreduction in the lowest price. Nevertheless, a number of socio-economicimpacts remain unquantifiable as of the current time and due to the limitedavailable data. It is recommended to incorporate more socio-economic effectsin future research in order to draw a more complete picture for all theinterested sectors, and to supplement the data with recent figures for 2012and 2013.Fiber till hemmet (Fiber-to-the-Home, FTTH) har talats om sedan fiberintroducerades på 1970-talet. Det håller numera på att bli grunden för vårtnya digitala samhälle, och bidra till ekonomiskt välstånd och medföra en mängdaffärsmässiga, sociala och underhållningsmässiga möjligheter tillslutanvändare. Den ökade efterfrågan på höghastighetsnät tas mer och mer påallvar och ett fiberbaserat nät kan hantera dessa ökade krav på grund av dessbreda bandbredd och tillförlitlighet. Idag finns ett praktiskt behov avkvantitativ analys av de socioekonomiska effekterna av fiberbaseradeaccessnät. Denna analys kan användas som en indikator och referens för allaintressenter när de överväger framtida investeringar. Sverige är ett lämpligtmålland för denna analys eftersom den har antagit fiber i några år och defördelar som FTTH har fört verkar redan vara synliga. Det huvudsakligavärdet av denna avhandling ligger i utredningen av kvantifierade bevis för desocioekonomiska effekterna av FTTH utbyggnad i Sverige. Detta har uppnåtts pågrundval av uppgifter från den Post- och telestyrelsen (PTS), Statistiskacentralbyrån (SCB), tidigare liknande studier och information som samlats inpå nätet från aktörer inom fiber, tillsammans med empirisk analys baserad påmultivariate regressionsmodeller. Resultatet visat att fiber har haft enbetydande inverkan på befolkningens utveckling, speciellt netto in- ochutflyttning till en kommun, vilket indikerar attraktionskraft kommunerna isig. Det är därför rimligt att föreslå att kommunerna och de lokalamyndigheterna överväger fiber driftsättning på allvar om de vill lockainvånare att stanna för ytterligare lokal utveckling. Studien analyserar ocksåkonkurrensen på fiberbaserade öppna nät och priserna på 10/10 Mbps symmetriskInternet-tjänst. Resultaten visar att nätverk med flera konkurrerandetjänsteleverantörer har ett bredare utbud av tjänster och ett lägre pris: jufler Internetleverantörer i ett fibernät, desto lägre konsumentpriser. Merspecifikt, för varje ny tjänsteleverantör som finns i nätverket, minskar detgenomsnittliga priset med 5 kronor per månad, och det lägsta priset med cirka7 kronor per månad. Ändå förblir ett antal socioekonomiska effekteromätbara på grund av begränsade tillgängliga data. Rekommendationen är attinförliva fler socioekonomiska effekter i framtida forskning för att dra enmer komplett bild för alla berörda sektorer, och att komplettera data medfärska siffror för 2012 och 2013.
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Francois, Frederic. "Policy-driven traffic engineering in energy-aware ISP backbone networks." Thesis, University of Surrey, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.606700.
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The excessive energy consumption of backbone networks is causing concerns among network operators. This thesis focuses on the design of Energy-aware Traffic Engineering (ETE) schemes which improve the energy-efficiency of different backbone networks by enabling the delivery of traffic by the smallest number of network devices so that the remaining devices can go to sleep during the periods of low traffic demands. The first proposed ETE scheme is called Time-driven Link Sleeping (TLS) which uses only two network routing topologies: the full topology with all links being active, and a reduced one with a subset of links sleeping. The key novelty of TLS lies in its ability to jointly optimize the reduced network topology and the off-peak period during which it is operated. Moreover, an extension to TLS makes it robust to single link failures. The second ETE scheme is a Green Load-balancing Algorithm (GLA) which complements TLS and other existing ETE schemes by jointly optimizing the IGP link weights in backbone networks for improved load-balancing and energy-efficiency after these existing ETE schemes put links to sleep. The final contribution is an online distributed ETE scheme called Green. Backup Paths (GBP) which dynamically diverts traffic from some selected links onto their backup paths, which were pre-installed to protect against link failure, so that these links have the opportunity to go to sleep without affecting the primary purpose of the backup paths. The distributed nature of GBP makes it scalable to large networks and be very responsive to sudden traffic changes since multiple routers can concurrently make interference-free decisions. The simple TLS scheme with GLA is ideally suited for networks which experience a regular traffic pattern because of their , offline nature while the more 'complex GBP scheme is more suitable when there is dynamic traffic because of its online nature.
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Trabé, Patrick. "Infrastructure réseau coopérative et flexible de défense contre les attaques de déni de service distribué." Toulouse 3, 2006. http://www.theses.fr/2006TOU30288.
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Les attaques par déni de service distribué (DDoS, Distributed Denial of Service) consistent à limiter ou à empêcher l'accès à un service informatique. La disponibilité du service proposé par la victime est altérée soit par la consommation de la bande passante disponible sur son lien, soit à l'aide d'un nombre très important de requêtes dont le traitement surconsomme les ressources dont elle dispose. Le filtrage des DDoS constitue aujourd'hui encore un problème majeur pour les opérateurs. Le trafic illégitime ne comporte en effet que peu ou pas de différences par rapport au trafic légitime. Ces attaques peuvent ensuite tirer parti et attaquer des services disposés dans le réseau. L'approche présentée dans cette thèse se veut pragmatique et cherche à aborder ce problème suivant deux angles ; à savoir contenir l'aspect dynamique et distribué de ces attaques d'une part, et être capable de préserver le trafic légitime et le réseau d'autre part. Nous proposons dans ce but une architecture distribuée de défense comportant des nœuds de traitement associés aux routeurs des points de présence et d'interconnexion du réseau de l'opérateur. Ces nœuds introduisent dans le réseau, par le biais d'interfaces ouvertes, la programmabilité qui apporte la flexibilité et la dynamicité requises pour la résolution du problème. Des traitements de niveau réseau à applicatif sur les datagrammes sont ainsi possibles, et les filtrages sont alors exempts de dommages collatéraux. Un prototype de cette architecture permet de vérifier les concepts que nous présentonsThe goal of Distributed Denial of Service attacks (DDoS) is to prevent legitimate users from using a service. The availability of the service is attacked by sending altered packets to the victim. These packets either consume a large part of networks bandwidth, or create an artificial consumption of victim’s key resources such as memory or CPU. DDoS’ filtering is still an important problem for network operators since illegitimate traffics look like legitimate traffics. The discrimination of both classes of traffics is a hard task. Moreover DDoS victims are not limited to end users (e. G. Web server). The network is likely to be attacked itself. The approach presented in this thesis is pragmatic. Firstly it seeks to control dynamic and distributed aspects of DDoS. Secondly it looks for protecting legitimate traffics and the network against collateral damages. Thus we propose a distributed infrastructure of defense based on nodes dedicated to the analysis and the filtering of the illegitimate traffic. Each node is associated with one POP router or interconnection router in order to facilitate its integration into the network. These nodes introduce the required programmability through open interfaces. The programmability offers applicative level packets processing, and thus treatments without collateral damages. A prototype has been developed. It validates our concepts
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Priškin, Jiří. "Vysokofrekvenční obvodový analyzátor s DDS." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2010. http://www.nusl.cz/ntk/nusl-218400.
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At first this thesis is dealing with the basic principles of network analyzers and afterwards goes to propose conception of a polyscope, as a special type of the scalar network analyzer, designed for magnitude frequency response measurement of two-port devices. As a result of this part of the thesis is the polyscope's block circuit diagram and also selection of key integrated circuits for sweep generator, logarithmic detector and control circuits. As the following part of the thesis is a design of the all basic analyzer's circuits resulting in their schematics diagrams and printed circuit boards, do assembly of all modules and mechanical construction of the instrument and look of the front panel. Some of the tasks is implementation of the firmware and personal computer application able to download measured data from the circuit analyzer via USB and generate chart in Microsoft Office Excel book.
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Puniyani, Kriti. "Spatiotemporal Gene Networks from ISH Images." Research Showcase @ CMU, 2013. http://repository.cmu.edu/dissertations/338.
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As large-scale techniques for studying and measuring gene expressions have been developed, automatically inferring gene interaction networks from expression data has emerged as a popular technique to advance our understanding of cellular systems. Accurate prediction of gene interactions, especially in multicellular organisms such as Drosophila or humans, requires temporal and spatial analysis of gene expressions, which is not easily obtainable from microarray data. New image based techniques using in-sit hybridization(ISH) have recently been developed to allowlarge-scale spatial-temporal profiling of whole body mRNA expression. However, analysis of such data for discovering new gene interactions still remains an open challenge. This thesis studies the question of predicting gene interaction networks from ISH data in three parts. First, we present SPEX2, a computer vision pipeline to extract informative features from ISH data. Next, we present an algorithm, GINI, for learning spatial gene interaction networks from embryonic ISH images at a single time step. GINI combines multi-instance kernels with recent work in learning sparse undirected graphical models to predict interactions between genes. Finally, we propose NP-MuScL (nonparanormal multi source learning) to estimate a gene interaction network that is consistent with multiple sources of data, having the same underlying relationships between the nodes. NP-MuScL casts the network estimation problem as estimating the structure of a sparse undirected graphical model. We use the semiparametric Gaussian copula to model the distribution of the different data sources, with the different copulas sharing the same covariance matrix, and show how to estimate such a model in the high dimensional scenario. We apply our algorithms on more than 100,000 Drosophila embryonic ISH images from the Berkeley Drosophila Genome Project. Each of the 6 time steps in Drosophila embryonic development is treated as a separate data source. With spatial gene interactions predicted via GINI, and temporal predictions combined via NP-MuScL, we are finally able to predict spatiotemporal gene networks from these images.
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Wang, Hong Feng. "IGP traffic engineering : a comparison of computational optimization algorithms." Thesis, Stellenbosch : Stellenbosch University, 2008. http://hdl.handle.net/10019.1/20877.
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Thesis (MSc)--Stellenbosch University, 2008.ENGLISH ABSTRACT: Traffic Engineering (TE) is intended to be used in next generation IP networks to optimize the usage of network resources by effecting QoS agreements between the traffic offered to the network and the available network resources. TE is currently performed by the IP community using three methods including (1) IGP TE using connectionless routing optimization (2) MPLS TE using connection-oriented routing optimization and (3) Hybrid TE combining IGP TE with MPLS TE. MPLS has won the battle of the core of the Internet and is making its way into metro, access and even some private networks. However, emerging provider practices are revealing the relevance of using IGP TE in hybrid TE models where IGP TE is combined with MPLS TE to optimize IP routing. This is done by either optimizing IGP routing while setting a few number of MPLS tunnels in the network or optimizing the management of MPLS tunnels to allow growth for the IGP traffic or optimizing both IGP and MPLS routing in a hybrid IGP+MPLS setting. The focus of this thesis is on IGP TE using heuristic algorithms borrowed from the computational intelligence research field. We present four classes of algorithms for Maximum Link Utilization (MLU) minimization. These include Genetic Algorithm (GA), Gene Expression Programming (GEP), Ant Colony Optimization (ACO), and Simulated Annealing (SA). We use these algorithms to compute a set of optimal link weights to achieve IGP TE in different settings where a set of test networks representing Europe, USA, Africa and China are used. Using NS simulation, we compare the performance of these algorithms on the test networks with various traffic profiles.
AFRIKAANSE OPSOMMING: Verkeersingenieurswese (VI) is aangedui vir gebruik in volgende generasie IP netwerke vir die gebruiksoptimering van netwerkbronne deur die daarstelling van kwaliteit van diens ooreenkomste tussen die verkeersaanbod vir die netwerk en die beskikbare netwerkbronne. VI word huidiglik algemeen bewerkstellig deur drie metodes, insluitend (1) IGP VI gebruikmakend van verbindingslose roete-optimering, (2) MPLS VI gebruikmakend van verbindingsvaste roete-optimering en (3) hibriede VI wat IGP VI en MPLS VI kombineer. MPLS is die mees algemene, en word ook aangewend in metro, toegang en selfs sommige privaatnetwerke. Nuwe verskaffer-praktyke toon egter die relevansie van die gebruik van IGP VI in hibriede VI modelle, waar IGP VI gekombineer word met MPLS VI om IP roetering te optimeer. Dit word gedoen deur `of optimering van IGP roetering terwyl ’n paar MPLS tonnels in die netwerk gestel word, `of optimering van die bestuur van MPLS tonnels om toe te laat vir groei in die IGP verkeer `of die optimering van beide IGP en MPLS roetering in ’n hibriede IGP en MPLS situasie. Die fokus van hierdie tesis is op IGP VI gebruikmakend van heuristieke algoritmes wat ontleen word vanuit die berekeningsintelligensie navorsingsveld. Ons beskou vier klasse van algoritmes vir Maksimum Verbindingsgebruik (MVG) minimering. Dit sluit in genetiese algoritmes, geen-uitdrukkingsprogrammering, mierkoloniemaksimering and gesimuleerde temperoptimering. Ons gebruik hierdie algoritmes om ’n versameling optimale verbindingsgewigte te bereken om IGP VI te bereik in verskillende situasies, waar ’n versameling toetsnetwerke gebruik is wat Europa, VSA, Afrika en China verteenwoordig. Gebruikmakende van NS simulasie, vergelyk ons die werkverrigting van hierdie algoritmes op die toetsnetwerke, met verskillende verkeersprofiele.
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Alila, Patrick. "Complementing network security to the ISO/IEC 27000 standard." Thesis, Linköpings universitet, Institutionen för teknik och naturvetenskap, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-96298.
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I syfte att öppna upp nya affärsmöjligheter för informationssäkerhetsföretaget Secure State AB, har detta arbete bedrivits för att komplettera företagets nuvarande standard för informationssäkerhetsarbete med ytterligare nätverkssäkerhet. Krav på slutresultatet var att dokumentet eller standarden skulle kunna komplettera ISO 27000, samt vara kostnadseffektivt. Efter en undersökning av den nämnda standarden konstaterades att enbart ISO 27000 i sig inte är ett fullgott verktyg för nätverkssäkerhetsarbete, på grund av dess icke-tekniska inriktning och målgrupp. Att komplettera ISO 27000 med av författaren utarbetade krav var inte heller att föredra, då syftet med ett standardiserat arbetssätt därmed försvinner. Det är bättre och attraktivare för kunden att använda sig av specifika tekniska standarder och rekommendationer. Sökandet efter en kompletterande standard påbörjades däför enligt dessa kriterier Kompatibilitet med ISO 27000 Teknisk inriktning Kostnadseffektiv Attraktiv att arbeta efter ISO 18028 uppfyller dessa krav mycket bra på samtliga punkter och är därmed bäst lämpad att arbeta efter av de tre standarder/rekommendationer som undersöktes mot kravlistan. Därför bör också Secure State välja att utföra nätverkssäkerhetsarbetet förankrat i ISO 18028 med följande förväntade resultat. Fig. 10, Förväntat resultat av komplettering till ISO 27000. Högst upp ser vi de allmäna informationssäkerhetspolicies samtliga anställda följer. Som nivå två finns ISO 27000, vilket är ledningens system för hur informationssäkerhetsarbetet övergripande ska hanteras. Längst ned ser vi den tekniska skyddsutrustningen som administreras av tekniker som följer lämpliga dokument. Denna rapport har identifierat ISO 18028 för säkerheten i nätverk, övriga återstår att vid behov identifiera för annan teknisk utrustning.
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Abujassar, Radwan Saoud. "Efficient recovery mechanisms over IGP and MANET networks." Thesis, University of Essex, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.558824.
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Routing protocols form an important key component in Mobile Ad-hoc Network (MANET) and Interior Gateway Protocol (IGP) networks, where every node (router) computes a shortest path to every other destination node, so the service can be delivered through this shortest path in a short time. Hence, failures in the shortest path lead to the degradation of network performance by increasing packet loss and delays in the demanded traffic. An incident of failure in the network is time-demanding to recover through routing protocol, as this necessitates re-constructing the routing table for the network topology and computing a new shortest path. During this process, delays in shortest path computations between some routers lead to the formation of routing loops, in which traffic circulates between two or more nodes many times before the routers construct an updated shortest path tree. When local loops occur in the network, the circulated traffic can increase link utilisation, create congestion, and affect other traffic passing along paths which also form a part of the loop. In this thesis, the performance implications of link or node failures in IGP and MANET networks are studied in detail. Several recovery mechanisms are proposed to reduce the impact of failure and guarantee a loop-free in the network. These mechanisms seek to reduce recovery time, which remains undesirably long in the current routing protocols in wired and wireless networks. The research was further extended to develop a recovery mechanism in MANET network to alleviate the impact of the frequent loss of connection due to the flexibility of free nodes, which move from one area to another without pre-notification. The idea behind recovery mechanism is to reduce current recovery time by constructing an alternative backup path in advance between source and destination, and then to reroute the traffic via this backup path when failure occurs.
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Windisch, Gerd. "Analyse, Modellierung und Verfahren zur Kompensation von CDN-bedingten Verkehrslastverschiebungen in ISP-Netzen." Doctoral thesis, Universitätsbibliothek Chemnitz, 2017. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-qucosa-220779.
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Ein großer Anteil des Datenverkehrs in „Internet Service Provider“ (ISP)-Netzen wird heutzutage von „Content Delivery Networks“ (CDNs) verursacht. Betreiber von CDNs verwenden Lastverteilungsmechanismen um die Auslastung ihrer CDN-Infrastruktur zu vergleichmäßigen (Load Balancing). Dies geschieht ohne Abstimmung mit den ISP-Betreibern. Es können daher große Verkehrslastverschiebungen sowohl innerhalb eines ISP-Netzes, als auch auf den Verbindungsleitungen zwischen ISP-Netz und CDNs auftreten.
In der vorliegenden Arbeit wird untersucht, welche nicht-kooperativen Möglichkeiten ein ISP hat, um Verkehrslastverschiebungen, welche durch Lastverteilungsmechanismen innerhalb eines CDNs verursacht werden, entgegenzuwirken bzw. abzumildern. Die Grundlage für diese Untersuchung bildet die Analyse des Serverauswahlverhaltens des YouTube-CDNs. Hierzu ist ein aktives Messverfahren entwickelt worden, um das räumliche und zeitliche Verhalten der YouTube-Serverauswahl bestimmen zu können. In zwei Messstudien wird die Serverauswahl in deutschen und europäischen ISP-Netzen untersucht. Auf Basis dieser Studien wird ein Verkehrsmodell entwickelt, welches die durch Änderungen der YouTube-Serverauswahl verursachten Verkehrslastverschiebungen abbildet. Das Verkehrsmodell wiederum bildet die Grundlage für die Bestimmung optimaler Routen im ISP-Netz, welche hohe Robustheit gegenüber CDN-bedingte Verkehrslastverschiebungen aufweisen (Alpha-robuste Routingoptimierung). Für die Lösung des robusten Routing-Optimierungsproblems wird ein iteratives Verfahren entwickelt sowie eine kompakte Reformulierung vorgestellt. Die Leistungsfähigkeit des Alpha-robusten Routings wird anhand von drei Beispielnetztopologien untersucht. Das neue Verfahren wird mit alternativen robusten Routingverfahren und einem nicht-robusten Verfahren verglichen. Neben der robusten Routingoptimierung werden in der Arbeit drei weitere Ideen für nicht-kooperative Methoden vorgestellt (BGP-, IP-Präix- und DNS-basierte Methode), um CDN-bedingten Verkehrslastverschiebungen entgegenzuwirken.
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Šišmiš, Lukáš. "Optimalizace IDS/IPS systému Suricata." Master's thesis, Vysoké učení technické v Brně. Fakulta informačních technologií, 2021. http://www.nusl.cz/ntk/nusl-445503.
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V dnešnom svete zrýchľujúcej sa sieťovej prevádzky je potrebné držať krok v jej monitorovaní . Dostatočný prehľad o dianí v sieti dokáže zabrániť rozličným útokom na ciele nachádzajúce sa v nej . S tým nám pomáhajú systémy IDS, ktoré upozorňujú na udalosti nájdené v analyzovanej prevádzke . Pre túto prácu bol vybraný systém Suricata . Cieľom práce je vyladiť nastavenia systému Suricata s rozhraním AF_PACKET pre optimálnu výkonnosť a následne navrhnúť a implementovať optimalizáciu Suricaty . Výsledky z meraní AF_PACKET majú slúžiť ako základ pre porovnanie s navrhnutým vylepšením . Navrhovaná optimalizácia implementuje nové rozhranie založené na projekte Data Plane Development Kit ( DPDK ). DPDK je schopné akcelerovať príjem paketov a preto sa predpokladá , že zvýši výkon Suricaty . Zhodnotenie výsledkov a porovnanie rozhraní AF_PACKET a DPDK je možné nájsť na konci diplomovej práce .
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Yousef, Mohammed Ali. "Analysis and mitigation of routing loops in IGP networks." Thesis, University of Essex, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.542354.
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Dubell, Michael, and David Johansson. "Nätverkssäkerhet med IPS : Förbättrad nätverkssäkerhet med Intrusion Prevention Systems." Thesis, Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE), 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:hh:diva-23347.
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Att skydda sin IT-miljö mot olika typer av intrång och attacker som till exempel trojaner,skadliga Java applets eller DoS attacker med hjälp av brandväggar och antivirusprogramär två viktiga lager i skalskyddet. I den här uppsatsen undersöks hur väl ett Intrusion Prevention System skulle kunna fungera som ett ytterligare lager i skalskyddet. Fokus ligger på hur väl IPS-systemet klarar av att avvärja attacker, hur mycket tid som går åt till konfigurering och drift för att få ett fungerande IPS samt hur prestandan i nätverket påverkas av implementationen. För att mäta hur väl IPS systemet klarar av att upptäcka och blockera attacker utförs två experiment där ett mindre nätverk attackeras på olika sätt. I det första experimentet skyddas infrastrukturen av en brandvägg och klienterna är utrustade med antivirusprogram. I det andra experimentet genomförs samma attacker igen fast med ett Snort IPS implementerat i nätverket. Resultatet av de genomförda experimenten visar att en IPS klarar att blockera ca 87% av attackerna, men nätverksprestandan påverkas negativt. Slutsatsen är att endast brandväggar och antivirusprogram inte ger ett fullgott skydd.
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Zhao, Fan, Yu Deng, and Xuan Qin. "Relationship and Network in Online B2B Business." Thesis, Linnéuniversitetet, Institutionen för marknadsföring (MF), 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-54209.
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Nowadays a new businesses form, online business occurred, which helps companies to improve their working efficiency in managing risks and allocating resources. Relationship and network are essential for understanding online business, which can help firms to reduce costs by outsourcing, and to increase efficiency by sharing information with cooperators. That leads to the purpose of this study, is to investigate how do the relationship and network between firms influence the cooperation of product developing and server operating companies within online business. In order to study this topic, the concepts from IMP group of characteristics of relationship, relationship development stages and the model of managing in networks are applied. Furthermore qualitative research method was employed for interviewing five companies in two types: 1) product developing companies 2) server operating companies. The relationship and network are perceived by interviewed companies are dynamic, fast changing and high technology focused. To cope with this phenomenon, most of companies choose to put their efforts on developing products and advancing technology rather than communicating with partners. In conclusion, the cooperation between firms in online business is influenced by fast changing and short-term relationships, high competition and the risk of plagiarism, which leads to competition focus in their business.
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Gracy, Sebin. "Input and State Observability of Linear Network Systems with Application to Security of Cyber Physical Systems." Thesis, Université Grenoble Alpes (ComUE), 2018. http://www.theses.fr/2018GREAT075/document.
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Cette thèse traite de la notion d’observabilité états-entrées (ISO) dans les systèmes de réseaux linéaires. On cherche des caractérisations graphiques en utilisant la notion de structure (resp. s-structural) ISO. Tout d’abord nous nous concentrons sur les systèmes de réseaux linéaires invariant en temps, représentés par des graphes fixes et fournissons des caractérisations pour structure ISO fortes. Par la suite, nous nous intéressons aux systèmes de réseaux linéaires variant en temps, dans lesquels nous nous concentrons d’abord sur le cas particulier des graphes fixes (la structure du graphe reste fixe mais les poids sur les arêtes peuvent varier à la dynamique qui varie dans le temps). Nous montrons que, sous des hypothèses appropriées sur la structure des matrices de commande, d’observation et d’action, l’ISO d’un système équivaut à l’observabilité d’un sous-système défini de manière appropriée. Par la suite, nous exploitons cette équivalence pour obtenir des caractérisations graphiques de l’ISO structurelle (resp. S-structurelles).Ensuite, pour la configuration du LTV, nous considérons le cas plus général des graphes variant en temps tout en ne faisant aucune hypothèse sur la structure des matrices du système. Nous introduisons deux descriptions appropriées de la collection complète de graphes, nommés graphes dynamiques et graphes dynamiques bipartites. Deux caractérisations équivalentes de l’ISO structurelle sont ensuite présentées en termes d’existence d’une liaison et d’une correspondance de taille appropriée, respectivement, dans le graphe dynamique et dans le graphe dynamique bipartite. Pour les ISO fortement structurelles, nous fournissons une condition suffisante et une condition nécessaire, concernant à la fois à l’existence d’une correspondance restreinte de taille appropriée dans le graphe dynamique bipartite et dans un sous-graphe de celle-ci. Lorsqu’il n’y a pas d’action directe de la commande sur les mesures, les deux conditions peuvent être fusionnées pour donner lieu à une condition nécessaire et suffisante.Enfin, nous présentons un algorithme récursif sans biais qui estime simultanément les états et les commandes. Nous nous concentrons sur les systèmes à retard-l inversibles avec retard intrinsèque l > 1, où la reconstruction de la commande est possible uniquement en utilisant des sorties allant jusqu’à un nombre "l" de temps plus tard. En montrant une équivalence avec un système de descripteurs, nous présentons des conditions dans lesquelles le filtre variant en temps converge vers un filtre stationnaire stable, impliquant la solution d’une équation algébrique à temps discret de RiccatiThis thesis deals with the notion of Input and State Observability (ISO) in linear network systems. One seeks graphical characterizations using the notion of structural (resp. s-structural) ISO. We first focus on linear time-invariant network systems ,represented by fixed graphs, and provide characterizations for strong structural ISO. Thereafter, we turn our attention to linear time-varying network systems wherein we first narrow our attention to the particular case of fixed graphs (i.e., the structure of the graph remains fixed; the weights along the edges are allowed to vary, thereby giving rise to time-varying dynamics). We show that, under suitable assumptions on the structure of input, output and feedthrough matrices, ISO of a system is equivalent to observability of a suitably defined subsystem. Subsequently, we exploit this equivalence to obtain graphical characterizations of structural (resp. s-structural) ISO.Thereafter, for the LTV setting, we consider the more general case of time-varying graphs and furthermore make no assumptions on the structure of system matrices. We introduce two suitable descriptions of the whole collection of graphs, which are named as dynamic graph and dynamic bipartite graph. Two equivalent characterizations of structural ISO are then stated in terms of existence of a linking and a matching of suitable size in the dynamic graph and in the dynamic bipartite graph, respectively. For strongly structural ISO, we provide a sufficient condition and a necessary condition, both concerning the existence of a uniquely restricted matching of suitable size in the dynamic bipartite graph and in a subgraph of it. When there is no direct feedthrough of the input on the measurements, the two conditions can be merged to give rise to a necessary and sufficient condition.Finally, we present an unbiased recursive algorithm that simultaneously estimates states and inputs. We focus on delay-$ell$ left invertible systems with intrinsic delay $ellgeq 1$, where the input reconstruction is possible only by using outputs up to $ell$ time steps later in the future. By showing an equivalence with a descriptor system, we state conditions under which the time-varying filter converges to a stationary stable filter, involving the solution of a discrete-time algebraic Riccati equation
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Grajek, Michał. "Network effects, compatibility, and adoption of standards." Doctoral thesis, Humboldt-Universität zu Berlin, Wirtschaftswissenschaftliche Fakultät, 2005. http://dx.doi.org/10.18452/15205.
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Diese Dissertation stellt ein strukturelles ökonometrisches Modell der Nachfrage mit direkten Netzwerkeffekten vor. Der strukturelle Ansatz ermöglicht es, den Umfang von Netzwerkeffekten and Netwerkkompatibilität zu identifizieren. Nach unserem Wissen ist es das erste Modell, das diese Identifikation im Falle von direkten Netzwerkeffekten ermöglicht. Gleichzeitig ist es der erste Versuch, den Umfang von Netzwerkkompatibilität mit ökonometrischen Methoden zu bestimmen. Das Modell wird dann angewandt, um die Nachfrage von Mobilfunkdienstleistungen, als auch den Zusammenhang zwischen ISO 9000 Normierung und internationalem Handel zu untersuchen. Die Schätzungsergebnisse führen zu interessanten wirtschaftspolitischen Folgerungen.This thesis introduces a structural econometric model of demand exhibiting direct network effects. The structural approach we follow allows us to identify the extent of network effects and compatibility between competing networks. To the best of our knowledge, this is the first model that facilitates the identification in the case of direct network effects. At the same time, it is the first attempt to assess the degree of compatibility in an econometric framework. The model is then applied to investigate demand for mobile telecommunications service and the link between adoptions of ISO 9000 standard and international trade. The estimation results allow us to formulate some interesting policy conclusions.
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Ngqondi, Tembisa Grace. "The ISO/IEC 27002 and ISO/IEC 27799 information security management standards : a comparative analysis from a healthcare perspective." Thesis, Nelson Mandela Metropolitan University, 2009. http://hdl.handle.net/10948/1066.
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Technological shift has become significant and an area of concern in the health sector with regard to securing health information assets. Health information systems hosting personal health information expose these information assets to ever-evolving threats. This information includes aspects of an extremely sensitive nature, for example, a particular patient may have a history of drug abuse, which would be reflected in the patient’s medical record. The private nature of patient information places a higher demand on the need to ensure privacy. Ensuring that the security and privacy of health information remain intact is therefore vital in the healthcare environment. In order to protect information appropriately and effectively, good information security management practices should be followed. To this end, the International Organization for Standardization (ISO) published a code of practice for information security management, namely the ISO 27002 (2005). This standard is widely used in industry but is a generic standard aimed at all industries. Therefore it does not consider the unique security needs of a particular environment. Because of the unique nature of personal health information and its security and privacy requirements, the need to introduce a healthcare sector-specific standard for information security management was identified. The ISO 27799 was therefore published as an industry-specific variant of the ISO 27002 which is geared towards addressing security requirements in health informatics. It serves as an implementation guide for the ISO 27002 when implemented in the health sector. The publication of the ISO 27799 is considered as a positive development in the quest to improve health information security. However, the question arises whether the ISO 27799 addresses the security needs of the healthcare domain sufficiently. The extensive use of the ISO 27002 implies that many proponents of this standard (in healthcare), now have to ensure that they meet the (assumed) increased requirements of the ISO 27799. The purpose of this research is therefore to conduct a comprehensive comparison of the ISO 27002 and ISO 27799 standards to determine whether the ISO 27799 serves the specific needs of the health sector from an information security management point of view.
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Goh, Mei Jean. "On implementing the ISO File Transfer, Access and Management protocol for a UNIX 4.2 BSD environment." Thesis, University of British Columbia, 1987. http://hdl.handle.net/2429/26263.
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Different computer systems have their own ways of representing, storing and managing files. One approach to facilitate file transfers among systems in a heterogeneous networked environment is for each system to locally map files for transfer onto a virtual filestore (VFS). Conceptually, a virtual filestore provides a universal model for describing files and how they can be manipulated.
The ISO File Transfer, Access and Management (FTAM) protocol offers one such virtual filestore model. This thesis reports on the prototype implementation of a useful subset of the ISO FTAM protocol for the UNIX 4.2 BSD¹ file system. We call this implementation ubcFTAM. UNIX files, ordinarily regarded as unstructured, can be endowed with some internal structure thereby allowing the transfer of selective portions of a file. Furthermore, the implementation offers several file attributes not supported by UNIX.
ubcFTAM runs on several Sun Workstations² interconnected by a 10 Mbps Ethernet.
Some performance data of ubcFTAM are also presented. This thesis also identifies several aspects of the specifications that are ambiguous or that are inadequate, warranting further studies. Resolutions for these issues are discussed. We hope this experience will be useful to others planning to implement FTAM for UNIX systems.
¹UNIX is a registered trademark of American Telephone and Telegraph Bell Laboratories. BSD denotes Berkeley Standard Distribution
²SUN Workstation is a trademark of Sun Microsystems, Inc.Science, Faculty of
Computer Science, Department of
Graduate
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Van, Rhyn Pierre. "Simplified field analysis of ISM-band OFDM-based industrial wireless sensor networks." Thesis, University of Pretoria, 2017. http://hdl.handle.net/2263/62798.
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A novel method is proposed to estimate committed information rate (CIR) variations in typical orthogonal frequency division multiplexing (OFDM) wireless local area networks (WLANs) that are applied in support of industrial wireless sensor networks (IWSNs) and operate within the industrial, scientific and medical (ISM) frequency bands. The method is based on the observation of a phenomenon of which the significance has not previously been recognized nor documented; here termed the service level differential zone (SLDZ). This method, which conforms to the ITU-T Y.1564 test methodology, provides the means to set a CIR reference for IEEE 802.11a/g/n OFDM systems in terms of committed throughput bandwidth between a test node and an access point (AP) at a specific range. An analytical approach is presented to determine the relationship between the maximum operating range (in metres) of a wireless sensor network for a specific committed throughput bandwidth, and its link budget (in dB). The most significant contributions of this study are the analytical tools to determine wireless network capabilities, variations and performance in a simplified method, which does not require specialised measurement equipment. With these it becomes possible for industrial technicians and engineers (who are not necessarily information technology (IT) network experts) to field analyse OFDM WLANs and so qualify their performance in terms of Y.1564 specified service level agreement (SLA) requirements, which is a primary requirement for WSNs that are intended for use in some specialised industrial applications.Die studie ondersoek ‘n nuwe metode om toevertroude oordraginformasietempo (OIT) van tipiese lokale IWM (industriële, wetenskaplike en mediese) band radiodatanetwerke te bepaal, wat gebaseer op ortogonale-frekwensiedeling multipleksering (OFDM), vir spesifieke toepassing in industriële radiosensor-netwerke (IRSNe) wat breëband deurlaatwerking vereis teen `n gespesifiseerde minimum diensvlak (DV) verwysing. Dié nuwe metode is gebaseer is op die waarneming van `n onbekende verskynsel wat vervolgens na verwys word as die diensvlak differensiële gebied (DVDG). Hierdie metode, wat ‘n aanpassing is vanaf die Internasionale Telekommunikasie Unie (ITU) se toetsmetodologie Y.1564, bemoontlik `n simplistiese wyse om `n gespesifiseerde deurlaatbandwydteverwysing tussen toetsnodus en aansluitingpunt (AP) te bepaal in terme van `n spesifieke reikafstand (in meter). `n Analitiese benadering word voorgestel om op `n eenvoudige wyse die verhouding te bepaal tussen die minimum deurlaat diensvlak bandwydteverwysing en die radioskakelbegroting, in desibel (dB). Die hoofbydrae van die studie is om aan die wetenskaplike gemeenskap die analitiese werktuie te voorsien wat benodig word om radionetwerkvermoëns, variasies en werkverrigting te bepaal, nie alleen volgens die aanvaarbare ruisvrye dinamiese bestek (RVDB) parameters nie, maar ook volgens die Y.1564 toetsmetodologie se voorgeskrewe diensvlakooreenkomste met betrekking tot industriële standaarde.
Thesis (PhD)--University of Pretoria, 2017.
Electrical, Electronic and Computer Engineering
PhD
Unrestricted
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Aristotelous, Andreas. "Single Board Computer for Standardized Onboard Vehicle Network." Thesis, KTH, Skolan för informations- och kommunikationsteknik (ICT), 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-188774.
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This master thesis project was carried in collaboration with Keolis AB. One of the company’s goals is to seek for a possible replacement to expensive custom hardware units by cheap single board computers. As a test case, a simple application is proposed, which implements driver identification by scanning the barcode of driving license (personnummer). The main objective of this project is to find a suitable single board computer, to implement the proposed driver identification application, to send the driving license number along with the timestamp in a web page and test the functionality of the single board computer according to procedures specified in ISO and IEC standards for road vehicles. A parser that analyzes the input string of a barcode reader was implemented in C programming language. The barcode reader scans a barcode or a QR code and the parser returns the content of the barcode symbol in ASCII character format. The driver license number as well as the timestamp should be published to a web page. A webpage was created using the Django Web Framework, which is a database-driven website. Each time a driving license barcode is scanned, a POST Http request method is performed and both the driving license and timestamp are stored in a SQLite database. Each time a GET request method is performed the data stored in the SQLite database is retrieved and presented in the website. The communication between the single board computer Raspberry Pi and the Django framework is achieved using cURL, which is an open source command line tool and library for transferring data with URL syntax. The data of the website will be manipulated in the backend. Moreover, heat and humidity environmental testing were performed as described in ISO and IEC standards for road vehicles, to evaluate the functionality of the system under certain environmental conditions. These tests showed the working temperature range and the humidity range that the Raspberry Pi can tolerate. As a conclusion, it can be stated that Raspberry Pi can be used in the passenger compartment with expected temperatures to be below 100 Celsius, but not in the engine compartment where temperatures more than 100 Celsius can occur. In addition, Raspberry Pi can perform in all the levels of humidity that has been tested. If it is necessary to be employed in other bus compartment with increased temperature, a more expensive robust embedded single board Linux computer should be chosen. Future work should include vibrations and immunity testing, in order to fully qualify with the ISO and IEC standards. These types of tests are costly and should therefore be performed by automotive manufacturers or other parties who are expected to bear such a cost.Detta examensarbete genomfördes i samarbete med Keolis Sverige AB. Ett av företagets mål är att söka efter möjliga system som ersättning till dyra, specialanpassade hårdvaruenheter och istället övergå till billiga enkortsdatorer. Som ett testfall föreslås ett enkelt program, som genomför identifiering av föraren genom att skanna streckkoden på körkortet (personnummer). Huvudsyftet med projektet är att hitta en lämplig enkortsdator, att implementera den föreslagna föraridentifieringsapplikationen, skicka körkortsnumret/personnumret med tidsstämpel till en webbsida och testa funktionaliteten hos enkortsdator enligt testrutiner som beskrivs av ISO- och IEC-standarder för vägfordon. En parser som analyserar indatasträngen av en streckkodsläsare implementerades i programmeringsspråket C. Streckkodsläsaren skannar en streckkod eller en QR-kod och parsern returnerar innehållet i streckkoden på ASCIIteckenformat. Körkortsnumret samt tidsstämpel publiceras på en webbsida. En webbsida har skapats med Django Web Framework, som är en databasdriven webbplats. Varje gång körkortets streckkod skannas, skickas en POST http-begäransmetod som utförs varvid både körkort och tidsstämpel lagras i en SQLite databas. Varje gång en GET-begäran skickas, lagras data i SQLite databasen och presenteras på webbplatsen. Kommunikationen mellan enkortsdatorn Raspberry Pi och ett Django-ramverk uppnås med hjälp av cURL, som är ett kommandoradsverktyg med öppen källkod, och ett bibliotek för att överföra data med URL-syntax. Uppgifterna på webbplatsen manipuleras i backend. Miljötålighetsprovning med avseende på värme- och fuktighet har utförts för att utvärdera systemets funktionalitet under specifika miljöförhållanden. Testerna specificeras i ISO- och IEC-standarder för vägfordon. Dessa tester visade vilka arbetstemperaturer och vilken luftfuktighet som Raspberry Pi klarar. Det kan konstateras att Raspberry Pi kan användas i passagerarutrymmet, där temperaturen förväntas ligga under 100 Celsius, men inte i motorrummet där temperaturer högre än 100 Celsius kan förekomma. Vidare har Raspberry Pi visat sig fungera vid de nivåer av luftfuktighet som har förkommit i testerna. I de fall där systemet skall användas i miljöer med högre temperaturer bör en dyrare och mer robust inbyggd (embedded) Linux-enkortsdator väljas. Det framtida arbetet bör omfatta vibrations- och elstörningstester för att fullt ut säkerställa att systemet klarar gällande ISO- och IEC-standarder. Dessa typer av test är kostsamma och bör därför genomföras av fordonstillverkare eller andra aktörer som förväntas kunna bära en sådan kostnad.
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Azevedo, Marcelo Teixeira de. "Cibersegurança em sistemas de automação em plantas de tratamento de água." Universidade de São Paulo, 2010. http://www.teses.usp.br/teses/disponiveis/3/3142/tde-10012011-121525/.
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Atualmente a segurança da informação tem sido uma preocupação constante das diversas instituições e países que utilizam recursos computacionais para comunicação e oferecimento de serviços. Métodos de proteção e contramedidas para redes tradicionais são conhecidos e comumente utilizados, tais como firewalls e detectores de intrusões. Para os sistemas de controle e aquisição de dados (Supervisory Control and Data Acquisition SCADA) não é diferente. Nos primórdios tais sistemas eram baseados em mainframes e arquitetura fechada, ou seja, dependentes dos fabricantes e consequentemente isolados de outros sistemas. Nos dias atuais os sistemas SCADA estão convergindo cada vez mais para plataformas baseadas em sistemas abertos e com a sua arquitetura fortemente apoiada em conectividade; sendo assim é usual a interligação de tais sistemas com a rede corporativa e em alguns casos com a própria internet. Partindo desse problema e com o atual desenvolvimento tecnológico em que se encontra a área de segurança da informação, é proposta uma metodologia para implantação de sistemas de automação em plantas de tratamento de água com ênfase em segurança e focada em sistemas industriais, utilizando as normas de segurança em automação ISA 99. Adicionalmente é proposto um mecanismo de análise e identificação de eventos maliciosos tendo por base o entendimento do fluxograma e etapas de uma planta de tratamento de água. Nesse sentido, os objetivos do presente trabalho são, em suma, estudar as normas, métodos e metodologias de segurança em sistemas industriais com foco em tratamento de água e propor uma metodologia cujo foco seja a minimização dos riscos de segurança. Para isso é proposto a avaliação de três cenários reais de tratamento de água para que assim seja possível simular os parâmetros de criticidade identificados no fluxograma e etapas do tratamento de água. Para tanto, desenvolveu-se um cenário conectado ao PLC que permitiu simular o comportamento e os impactos, além de um detector de eventos para análise dos resultados.Currently, information security is a constant concern of the several institutions and countries that use computing resources for communication and service offering purposes. Protection methods and countermeasures for traditional networks such as firewalls and intrusion detectors are known and ordinarily used. The same goes for control systems and data acquisition (Supervisory Control and Data Acquisition - SCADA). In the beginning, such systems were based on mainframes and closed architecture, i.e., dependent on manufacturers and consequently isolated from other systems. Nowadays, the SCADA systems converge more and more to platforms based on open systems, with its architecture strongly relied on connectivity; thus, it is usual the interconnection of such systems with the corporate network and, in some cases, with Internet itself. From this issue, and with the current technology development in the information security area, a methodology is proposed to implement automation systems in water treatment plants with an emphasis on security, and focused on industrial systems, using automation safety rules ISA 99. The purpose of this essay is, in brief, to study safety rules, methods and methodologies for industrial systems with a focus on water treatment, and to propose a methodology directed to the minimization of safety hazards. For that purpose, it is proposed the evaluation of three water treatment real scenarios so that it is possible to simulate criticality parameters identified in the flow chart and stages of the water treatment. Therefore, a scenario connected to PLC was developed, allowing the simulation of the behavior and the impacts, in addition to an event detector for the result analysis.
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Tillberg, Emil. "Controller Area Network : Möjlig CAN-buss lösningar inom entreprenadbranschen." Thesis, Mittuniversitetet, Avdelningen för kvalitets- och maskinteknik, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:miun:diva-36881.
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Företaget engcon Nordic AB producerar redskap till entreprenadbranschen, där tiltrotator är hjärtat i deras verksamhet. För att förbättra användningen och förenkla installationen har en litteraturstudie gjorts som tittar på två delar, funktionen kring CAN-buss som grund för ett kommunikationssystem, och olika högre lager protokoll som byggs ovanpå CAN. Varför CAN-buss skapades och hur systemet fungerar är viktiga att förstå för att kunna titta på dem ovanliggande lager, kallade HLP (Higher Layer Protocol). HLP ger ett slags maskin-människa gränssnitt att arbeta emot. Typer av HLP kan vara J1939, ISOBUS eller annan. CAN-buss är den de facto standarden vad gäller fordonsnätverk där ECU:er, kallad noder, kommunicerar på en gemensam kommunikationsstam, kallad buss. För att göra detta har en snillrik teknik tagits fram för att prioritera meddelanden mellan noder, som ger datamässigt förlustfri medling. CAN-buss har även ett avancerat feldetekteringssystem på kommunikationen som ger den dess robusthet i krävande miljöer. Vad gäller olika HLP finns en mängd av dessa inom olika branscher. Alla har de gemensamt att de bygger upp ett mer eller mindre användarvänligt gränssnitt som går att implementera ovanpå CAN. Inom till exempel jordbruket använder man i hög utsträckning ISOBUS som är en egen branschstandard som delvis ser förbi konkurrensen inom sektor för att bygga ett enkelt, användarvänligt system som gynnar slutkunden på bästa sätt. Inom automation används istället CANopen, som är ett öppet system som tillåter hög interoperabilitet mellan olika enheter med så kallad profilering. Ett sista system som används inom en rad olika branscher heter CanKingdom och är det mest anpassningsbara systemet inom denna studie. För att få reda på mer branschspecifik information kring lösningar och problem gjordes även en intervjustudie inom projektet. Här intervjuades personer aktiva inom olika företag som jobbar med CAN baserade system på något sätt. Intervjuerna gjordes för att titta på relevanta problem inom deras specifika område. Som resultat specificeras fyra alternativ som projektägaren bör titta vidare på för att hitta ett system som passar dem. Det bygger på alternativ som antingen kräver access till befintlig J1939 buss, eller att bygga en mer eller mindre adapterad modell byggd på ISOBUS, CANopen eller CanKingdom.The company engcon Nordic AB produces equipment for the construction industry, where the product called tiltrotator is the heart of their business. To improve the use and simplify the installation, a literature study has been made that looks at two parts, first the function around CAN bus as the basis for a communication system and secondly various higher layer protocols (HLP) built on top of CAN. Why CAN bus was created and how the system works is important to understand in order to look at these overlying layers, called HLP (Higher Layer Protocol), which provides a kind of machine-human interface to work with. Different types of HLP can be J1939, ISOBUS or other. CAN bus is the de facto standard for vehicle networks where ECUs (Electronic Control Unit), called nodes, communicating on a common communication network, called bus. To do this, an ingenious technique has been developed to prioritize messages between nodes, which provides data loss-free arbitration. In CAN an advanced technique for error detection on the communication has been applied, and gives CAN the robustness to be applied in tough environment. As for various HLPs, a large number of these are available in different industries. Every one of these HLP has a common that they try to build a more or less user-friendly interface that can be implemented on top of CAN. For example, in the agricultural industry, the use of ISOBUS is common, which is an industrial standard that goes beyond competition to build a simple, user-friendly system that benefits the customer to the best possible extent. In automation, instead, CANopen is used, which is an open system that allows high interoperability between different units with so-called profiling. One last system used in a number of industries is called CanKingdom and is the most adaptable system in this project. In order to find out more industry-specific information about solutions and problems, an interview study was also conducted within the project. Here, various people were interviewed, active in different companies that are involved in CAN-based systems. This was done to look at relevant problems in their specific area. As a result, four options are specified which the project owner should look at in order to find a system that suits them. It is based on alternatives that either require access to the existing J1939 bus, or to build a more or less adapted model built on ISOBUS, CANopen or CanKingdom.
Betyg: 2019-08-15
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Tomaga, Jakub. "Metodika zavedení síťové bezpečnosti v softwarové společnosti." Master's thesis, Vysoké učení technické v Brně. Fakulta podnikatelská, 2013. http://www.nusl.cz/ntk/nusl-224224.
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This thesis deals with network security and its deployment in the real environment of the software company. The thesis describes information management framework with a specific concentration on computer networks. Network security policy is designed as well as network infrastructure modifications in order to increase the level of security. All parts of the solution are also analyzed from financial point of view.
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Waseem, Athar, and A. H. M. Sadath Hossain. "MIMO Channel Equalization and Symbol Detection using Multilayer Neural Network." Thesis, Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-2345.
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In recent years Multiple Input Multiple Output (MIMO) systems have been employed in wireless communication systems to reach the goals of high data rate. A MIMO use multiple antennas at both transmitting and receiving ends. These antennas communicate with each other on the same frequency band and help in linearly increasing the channel capacity. Due to the multi paths wireless channels face the problem of channel fading which cause Inter Symbol Interference (ISI). Each channel path has an independent path delay, independent path loss or path gain and phase shift, cause deformations in a signal and due to this deformation the receiver can detect a wrong or a distorted signal. To remove this fading effect of channel from received signal many Neural Network (NN) based channel equalizers have been proposed in literature. Due to high level non-linearity, NN can be efficient to decode transmitted symbols that are effected by fading channels. The task of channel equalization can also be considered as a classification job. In the data (received symbol sequences) spaces NN can easily make decision regions. Specifically, NN has the universal approximation capability and form decision regions with arbitrarily shaped boundaries. This property supports the NN to be introduced and perform the task of channel equalization and symbol detection. This research project presents the implementation of NN to be use as a channel equalizer for Rayleigh fading channels causing ISI in MIMO systems. Channel equalization has been done using NN as a classification problem. The equalizer is implemented over MIMO system of different forms using Quadrature Amplitude Modulation scheme (4QAM & 16QAM) signals. Levenberg-Marquardt (LM), One Step Secant (OSS), Gradient Descent (GD), Resilient backpropagation (Rprop) and Conjugate Gradient (CG) algorithms are used for the training of NN. The Weights calculated during the training process provides the equalization matrix as an estimate of Channel. The output of the NN provides the estimate of transmitted signals. The equalizer is assessed in terms of Symbol Error Rate (SER) and equalizer efficiency.
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Pelevin, Dmitrii. "Research of methods and algorithms of insider detection in a computer network using machine learning technologies." Thesis, Blekinge Tekniska Högskola, Institutionen för datavetenskap, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-21877.
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Background. Security Information and Event Management (SIEM) systems today are sophisticated sets of software packages combined with hardware platforms, which can perform real-time analysis on security events and can respond to them before potential damage due to the actions of intruders. A huge number of systems rely on the continuous transmission of data through computer networks. Nowadays it is difficult to imagine a sphere of human activity that would not be affected by information technologies and would not use computer networks. Along with the means of protecting information, the technologies that are used by cybercriminals to achieve their goals are also improving. Moreover, the so-called insiders - information security perpetrators inside the protected perimeter, who can cause much more damage by their actions, as they are among the legitimate users and can have access to more confidential information - are becoming a growing threat. Objectives. To identify insider activity within an acceptable time inside the network, we need to develop a methodology to detect abnormal activity within the network using advanced data processing techniques, based on machine learning. After recreating the data processing system, we will also need to determine the most efficient algorithm that can be applied to the task of insider detection. Methods. The work analyzed research papers with similar objectives to investigate methods and technologies for securing against intruder intrusions, in conjunction with a study of machine learning techniques for detecting anomalies in the data. Experimental data were also collected containing information about network activity within the same network over two weeks. With this data, it is possible to conduct an experiment in network traffic processing using state-of-the-art technology. Results. During the study of relevant works, several effective ways to detect anomalies in the data were identified, technologies for processing large amounts of data using NoSQL were studied, and work on creating an experimental bench was performed. As a result, the experimental data obtained was sufficient to verify the effectiveness of the obtained solution. Conclusions. As a result, we analyzed existing approaches to detect insider activity within a computer system. Algorithms based on machine learning and big data processing methods were evaluated. In addition, a model for representing big data in NoSQL format was developed, which made it possible to create an architecture of a system for detecting insiders in computer networks using a graph database and machine learning methods.
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Frost, Per. "Utvärdering av den upplevda användbarheten hos CySeMoL och EAAT med hjälp av ramverk för ändamålet och ISO/IEC 25010:2011." Thesis, KTH, Industriella informations- och styrsystem, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-138576.
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This report describes a study aimed at uncovering flaws and finding potential improvements from when the modelling tool EAAT is used in conjunction with the modelling language CySeMoL. The study was performed by developing a framework and applying it on CySeMoL and EAAT in real life context networks. The framework was developed in order to increase the number of flaws uncovered as well as gather potential improvements to both EAAT and CySeMoL. The basis of the framework is a modified version of the Quality in use model from ISO/IEC 25010:2011 standard. Upon the characteristics and sub characteristics of this modified model different values for measuring usability where attached. The purpose of these values is to measure usability from the perspectives of both creating and interpreting models. Furthermore these values are based on several different sources on how to measure usability. The complete contents of the framework and the underlying ideas, upon which the framework is based, are presented in this report. The framework in this study was designed in order to enable it to be used universally with any modelling language in conjunction with a modelling tool. Its design is also not limited to the field of computer security and computer networks, although that is the intended context of CySeMoL as well as the context described in this report. However, utilization outside the intended area of usage will most likely require some modifications, in order to work in a fully satisfying. Several flaws where uncovered regarding the usability of CySeMoL and EAAT, but this is also accompanied by several recommendations on how to improve both CySeMoL and EAAT. Because of the outline of the framework, the most severe flaws have been identified and recommendations on how to rectify these shortcomings have been suggested.
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Kukla, Michal. "Ray-tracing s knihovnou IPP." Master's thesis, Vysoké učení technické v Brně. Fakulta informačních technologií, 2010. http://www.nusl.cz/ntk/nusl-237265.
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Master thesis is dealing with design and implementation of ray-tracing and path-tracing using IPP library. Theoretical part discusses current trends in acceleration of selected algorithms and also possibilities of parallelization. Design of ray-tracing and path-tracing algorithm and form of parallelization are described in proposal. This part also discusses implementation of adaptive sampling and importance sampling with Monte Carlo method to accelerate path-tracing algorithm. Next part is dealing with particular steps in implementation of selected rendering methods regarding IPP library. Implementation of network interface using Boost library is also discussed. At the end, implemented methods are subjected to performance and quality test. Final product of this thesis is server aplication capable of handling multiple connections which provides visualisation and client application which implements ray-tracing and path-tracing.
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Klíma, Jan. "Bezdrátové komunikační moduly pro mikrokontroléry." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2011. http://www.nusl.cz/ntk/nusl-219328.
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The aim of this master’s thesis is analysis of wireless communication between mikroprocesors. The first part of the work are analysed the problems the wireless free ISM band. Mainly RFM12B and ZigBee module, which i these band work and ZigBee standart. The second part are described relazation board for both module. Further how programming ZigBee module. And at last programs for tested module.
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Doubková, Veronika. "Bezpečnostní rizika podle standardu ISO 27001." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2020. http://www.nusl.cz/ntk/nusl-412984.
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This diploma thesis deals with the management of security information, according to ISO/IEC 27005 and it is implementation in the Verinice software environment. The risk information management process is applied to a critical infrastructure, that is connected to a optical fiber network. The work focuses on incidents aimed at threatening data from optical threats and active network elements in transmission systems. The result of the work is defined as a risk file in the .VNA format containing identified risks, for which appropriate measures are implemented in connection with the requirements of ISO/IEC 27001, for the protection of critical infrastructures and transmitted data in the transmission system.
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Silva, Rodrigo. "ITS-based decision making mechanism for opportunistic networking in heterogeneous network environment." Thesis, Ecole nationale supérieure Mines-Télécom Atlantique Bretagne Pays de la Loire, 2020. http://www.theses.fr/2020IMTA0174.
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Le nombre de véhicules connectés augmentent et pour une utilisation plus intelligente des systèmes de transport, les véhicules ont besoin d’accroître leur connaissance de l’environnement. Cela peut être atteint en permettant aux véhicules de communiquer avec leur environnement. Pour une connectivité omniprésente, il sera nécessaire d’utiliser diverses technologies sans fil, existantes. Dans un tel environnement de réseau d’accès hétérogène, il est nécessaire de fournir aux applications des mécanismes décisionnels transparents pour gérer l’affectation des flux de données sur les réseaux disponibles. Dans cette thèse, nous proposons le Ant-based Decision Maker for Opportunistic Networking (AD4ON), un Decision Maker (DM) mécanisme modulaire capable de choisir le meilleur profil de communication disponible pour chaque fluxde données dans un environnement de réseau hétérogène et dynamique. Le mécanisme proposé gère les exigences et préférences de différents acteurs (applications, utilisateurs,etc.), ainsi que les information réseaux dans un futur proche, afin de prendre des décisions plus intelligentes. C’est-à-dire, afin d’augmenter la satisfaction de chaque acteur impliqué dans le processus de communication, ainsi que d’augmenter la stabilité de la décision (par exemple, en réduisant l’effet “ping-pong“)Demand from different actors for extended connectivity where vehicles can exchange data with other devices have pushed vehicle manufacturers to invest in embedded solutions, which paves the way towards Cooperative Intelligent Transportation Systems (C-ITS). Cooperative vehicles enable the development of an ecosystem of services around them. Due to the heterogeneousness of such services and their specific requirements, for ubiquitous connectivity it is necessary to combine existing wireless technologies, providing applications with a communication architecture that hides such underlying access technologies specificities. Moreover, due to vehicles’ high velocity it is needed a Decision Maker (DM) mechanism capable to take into account the short-term prevision about network environment in order to better manage all flow communications. Based on the Intelligent Transportation Systems (ITS) architecture proposed by International Organization for Standardization (ISO), we proposed the Ant-based Decision Maker for Opportunistic Networking (AD4ON), a modular decision maker mechanism capable to choose the best available access network for each data flow in an heterogeneous and dynamic network environment. The proposed mechanism manages requirements and preferences from different actors, taking into account the short-term prevision about the network environment. Simulations have demonstrated that the AD4ON outperforms current benchmark algorithms, by increasing decision’s stability, reducing the “ping-pong” effect and maximizing flow’s satisfaction. Moreover, we demonstrate that taking into account the short-term prevision, the AD4ON can optimize the algorithm reaction time
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Junior, Dagoberto Carvalio. "Uma plataforma para avaliar a degradação da vazão causada por interferência espectral em redes sem fio padrão IEEE 802.11." Universidade de São Paulo, 2010. http://www.teses.usp.br/teses/disponiveis/55/55134/tde-30032011-091330/.
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A interferência espectral gera patologias nos sistemas de comunicação sem fio (wireless), como por exemplo, quedas na comunicação e degradação na vazão. O espectro de RF (rádio frequência) é fiscalizado e controlado por órgãos governamentais, no entanto as redes sem fio padrão IEEE 802.11, conhecidas por WLANs (Wireless Local Area Networks), trabalham em faixas espectrais não licenciadas, conhecidas por ISM. Estas redes estão cada vez mais presentes nos ambientes comerciais e residenciais, contribuindo para questões de ubiquidade e acesso à Internet. Com este aumento expressivo, a cobertura espectral está cada vez mais densa. A densidade elevada de sinais aponta para a saturação do espectro ISM, causando interferências mútuas das redes IEEE 802.11. O objetivo deste trabalho é analisar a cobertura do espectro, por redes WLANs, e avaliar quedas de vazão ocasionadas por interferências espectrais, variando no espaço e no tempo. Dois cenários foram mapeados para analisar as degradações, um com baixa a média e outro com alta densidade e complexidade. O objetivo da criação desses cenários foi comparar as degradações causadas pelas interferências em ambientes diferentes, na ocupação, na utilização e na propagação de sinais de redes WLANs. Através dos resultados obtidos, um ciclo de vida de gerenciamento do espectro de redes padrão 802.11 foi proposto. Este ciclo contribui para avaliar e classificar o estado de uma rede em densa, não densa, complexa e não complexa, visto que alterações de ocupação do espectro no espaço e no tempo são plausíveis de ocorrerem. Conclui-se que os impactos da sobreposição total do canal, por fontes 802.11, não são suficientes para a substancial degradação da vazão em ambientes de baixa a média complexidade. Em ambientes com alta densidade e complexidade as degradações são mais evidentes, principalmente quando ocorrem perturbações vindas de duas fontes adjacentesThe spectral interference generates pathologies in wireless communication systems (wireless), such as declines in communication and degradation in flow. The spectrum of RF (radio frequency) is supervised and controlled by government agencies, however the wireless standard IEEE 802.11, known as WLANs (Wireless Local Area Networks), work in unlicensed spectrum bands, known as ISM. These networks are increasingly involved in commercial and residential environments, contributing to issues and ubiquity of Internet access. With the significant increase in these networks, the spectral coverage is increasingly dense. The high density of signals pointing to the saturation of the ISM spectrum, causing mutual interference of IEEE 802.11 networks. The aim of this study is to analyze the coverage of the spectrum, for WLANs, and evaluate the flow falls caused by spectral interferences, varying in space and time. Two scenarios were mapped to examine the degradations, with a low to medium and one with high density and complexity. The purpose of creating these scenarios was to compare the degradation caused by interference in different environments, occupation, use and spread of signals WLANs. Through the results, a life cycle management of the spectrum of standard 802.11 networks was proposed. This cycle helps to evaluate and classify the state of a dense network, not dense, complex and not complex, since changes in occupation of the spectrum - in space and time - are plausible to occur. It is concluded that the impacts of the complete overlap of the channel, sources 802.11, are not sufficient to the substantial degradation of the flow in low to medium complexity. In environments with high density and complexity of the degradation is more evident, especially when there are disturbances coming from two adjacent sources
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Jin, Xiao Ling Kathy. "Understanding the sustainability of online question answering communities in China : the case of "Yahoo! Answers China" /." access abstract and table of contents access full-text, 2009. http://libweb.cityu.edu.hk/cgi-bin/ezdb/thesis.pl?phd-is-b30082328f.pdf.
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Thesis (Ph.D.)--City University of Hong Kong, 2009."Submitted to Department of Information Systems in partial fulfillment of the requirements for the degree of Doctor of Philosophy." Includes bibliographical references (leaves 88-106)
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Šoustar, Jiří. "Modul rozhraní Ethernet pro platformu FITkit." Master's thesis, Vysoké učení technické v Brně. Fakulta informačních technologií, 2008. http://www.nusl.cz/ntk/nusl-235428.
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This graduation thesis is aimed at design and implementation of embedded systems, network communication and support of the network communication for embedded systems. Furthermore it introduces school platform FITkit and offers a conceptional extension of the network interface for this platform based on Ethernet network standard. Based on that conception I'm trying to find and describe suitable solution for FITkit platform which realizes a network interface as a form of extension module capable of development supporting.
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Pham, Thanh Son. "Autonomous management of quality of service in virtual networks." Thesis, Compiègne, 2014. http://www.theses.fr/2014COMP2147/document.
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Cette thèse propose un schéma entièrement distribué de routage résilient pour les réseaux de switches. Dans cette approche une panne est traitée localement ; ainsi les autres nœuds du réseau n’ont pas besoin de prendre des mesures spécifiques. Contrairement aux systèmes classiques de routage IP qui se base uniquement sur la destination, le routage est fait en se basant sur l’arc de l’entrée et la destination. La contrainte qui en résulte est que les deux flux à la même destination entrant dans un nœud par un arc commun doivent fusionner après cet arc. Nous montrons que sous des faibles hypothèses (en supposant que le réseau est symétrique et bi-connexes au sens des liens), il existe un schéma de routage résilient pour toutes les situations de pannes simples de liens. Nous modélisons le problème de dimensionnement par un programme linéaire en nombres entiers qui peut être résolu exactement pour des réseaux de taille modeste. Nous proposons également plusieurs heuristiques pour traiter des instances de grande taille. Notre méthode généralise les méthodes de la littérature, en particulier celles de Xi et al. et de Nelakuditi et al. qui ont proposé des approches similaires. Notre approche permet d’obtenir de meilleurs résultats sur de nombreuses instances de test. Nous avons également étudié l’existence d’un schéma de routage résilient pour situation de panne de nœud dans le réseau basée sur les switches. Nous montrons que dans le cas des pannes de plusieurs liens, la condition de connexité n’est pas suffisanteThis thesis presents a fully distributed resilient routing scheme for switch-based networks. A failure is treated locally, so other nodes in the network do not need to undertakespecial actions. In contrast to conventional IP routing schemes, each node routesthe traffic on the basis of the entering arc and of the destination. The resulting constraintis that two flows to the same destination entering in a node by a common archave to merge after this arc. We show that this is sufficient for dealing with all singlelink failure situations, assuming that the network is symmetric and two-link connected.We model the dimensioning problem with an Integer Linear Program which can besolved exactly for small networks. We also propose several heuristics for larger networks.Our method generalizes the methods of Xi et Chao and Li and of Nelakuditiet al. who have proposed similar schemes in the context of IP. Our methods are moreefficient than previous ones. We have also studied the existence of a resilient routingscheme for single node failure situation in switch-based network. We study also thecase of multi-link failure situations and show that requiring the network to be connectedafter any failure does not guarantee the existence of a resilent routing schemeas described above
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Kapusta, Martin. "Laboratorní úlohy pro výuku síťových technologií." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2019. http://www.nusl.cz/ntk/nusl-400886.
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The aim of the diploma thesis is to choose network simulator suitable for network technologies laboratory tasks for educational use. Theoretical part of thesis describes basics of network communication, addressing, reference models. Thesis also describes standards Wi Fi, Ethernet and routing protocol OSPF - technologies which are discussed in laboratory tasks. The practical part of diploma thesis describes a few available network simulators suitable for creating two laboratory tasks. Finally, the NS-3 simulator was chosen. Both laboratory tasks include theoretical introduction, detailed description of source code, individual tasks, expected outputs and control questions which senses understanding of discussed technologies.
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Reinecke, Isa [Verfasser], Dirk [Akademischer Betreuer] Fornahl, Dirk [Gutachter] Fornahl, and Jörg [Gutachter] Freiling. "The role of ego-centred networks in entrepreneurship / Isa Reinecke ; Gutachter: Dirk Fornahl, Jörg Freiling ; Betreuer: Dirk Fornahl." Bremen : Staats- und Universitätsbibliothek Bremen, 2018. http://d-nb.info/1165772272/34.
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Elmes, Katherine. "Networks of Ambiguity in Project-Based Learning: Understanding How Students Experience and Manage Ambiguity in WPI's IQP Experience." Digital WPI, 2018. https://digitalcommons.wpi.edu/etd-theses/1255.
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WPI’s global and off-campus IQPs, rich with real-world sponsors/projects and increasingly diverse teams, require that both faculty and students navigate a network of ambiguous situations and relationships. Despite the increasing adoption of project-based learning as a preferred educational model across higher education, and the prevalence of project-based work in STEM careers, research on how to best prepare students and faculty to identify and navigate ambiguity inherent to project-based learning is limited. Seeking to fill this important gap, this graduate thesis advances a pilot qualitative study focused on how students in domestic and off campus IQPs experience and navigate ambiguity in their IQPs. The thesis presents preliminary grounded
theory regarding the types of ambiguity experienced by students, how students navigate through the ambiguity, and elements that appear to impact a student’s success in that navigation.
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Reinecke, Isa Verfasser], Dirk [Akademischer Betreuer] [Fornahl, Dirk Gutachter] Fornahl, and Jörg [Gutachter] [Freiling. "The role of ego-centred networks in entrepreneurship / Isa Reinecke ; Gutachter: Dirk Fornahl, Jörg Freiling ; Betreuer: Dirk Fornahl." Bremen : Staats- und Universitätsbibliothek Bremen, 2018. http://nbn-resolving.de/urn:nbn:de:gbv:46-00106688-19.
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Mihailovic, Andrej. "Mobility support for IP-based wireless networks." Thesis, King's College London (University of London), 2004. https://kclpure.kcl.ac.uk/portal/en/theses/mobility-support-for-ip--based-wireless-networks(b643754c-5730-4c62-a323-f5bf17768e89).html.
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Chen, Yan. "Traitement transactionnel dans un environnement OSI." Grenoble 2 : ANRT, 1988. http://catalogue.bnf.fr/ark:/12148/cb376126461.
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