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A network approach for power grid robustness against cascading failures

Wang, X. (author), Koc, Y. (author), Kooij, R.E. (author), Van Mieghem, P. (author)

Cascading failures are one of the main reasons for blackouts in electrical power grids. Stable power supply requires a robust design of the power grid topology. Currently, the impact of the grid structure on the grid robustness is mainly assessed by purely topological metrics, that fail to capture the fundamental properties of the electrical...

conference paper 2015

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Quantifying the robustness of metro networks

Wang, X. (author), Koç, Y. (author), Derrible, S. (author), Nasir Ahmad, Sk. (author), Kooij, R.E. (author)

Metros (heavy rail transit systems) are integral parts of urban transportation systems. Failures in their operations can have serious impacts on urban mobility, and measuring their robustness is therefore critical. Moreover, as physical networks, metros can be viewed as network topological entities, and as such they possess measurable network...

conference paper 2015

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The Impact of the Topology on Cascading Failures in a Power Grid Model

Koç, Y. (author), Warnier, M. (author), Van Mieghem, P. (author), Kooij, R.E. (author), Brazier, F.M.T. (author)

Cascading failures are one of the main reasons for large scale blackouts in power transmission grids. Secure electrical power supply requires, together with careful operation, a robust design of the electrical power grid topology. Currently, the impact of the topology on grid robustness is mainly assessed by purely topological approaches, that...

journal article 2014

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Estimating the impact of single and multiple freezes on video quality

Van Kester, S. (author), Xiao, T. (author), Kooij, R.E. (author), Brunnstrom, K. (author), Ahmed, O.K. (author)

This paper studies the impact of freezing of video on quality as experienced by users. Two types of freezes are investigated. First a freeze where the image pauses, so no frames were lost (frame halt). In the second type of freeze, the image freezes and skips that part of the video (frame drop). Measuring Mean Opinion Score (MOS) was done by...

journal article 2011

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Graphs with given diameter maximizing the algebraic connectivity

Wang, H. (author), Kooij, R.E. (author), Van Mieghem, P. (author)

We propose a class of graphs G?D(n1, n2, ..., nD+1), containing of a chain of D+1 cliques Kn1 , Kn2 , ..., KnD+1, where neighboring cliques are fully-interconnected. The class of graphs has diameter D and size N = ? 1?i?D+1ni. We prove that this class of graphs can achieve the maximal number of links, the minimum average hopcount, and more...

journal article 2010

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Techniques for measuring quality of experience

Kuipers, F. (author), Kooij, R. (author), De Vleeschauwer, D. (author), Brunnström, K. (author)

Quality of Experience (QoE) relates to how users perceive the quality of an application. To capture such a subjective measure, either by subjective tests or via objective tools, is an art on its own. Given the importance of measuring users’ satisfaction to service providers, research on QoE took flight in recent years. In this paper we present...

conference paper 2010

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One Thousand Flowers in Delft: A Bottom-up approach to improve teaching international students

Brummelink, M.L. (author), Frantzeskaki, N. (author), Klaassen, R.G. (author), Blom, E.M. (author), Kooij, R.E. (author), Kroesen, J.O. (author), Stadler, D.I. (author), Van den Boogaard, M.E.D. (author)

Delft University of Technology (DUT) is becoming more and more an international community. Since lectures on master level are all conducted in English, the numbers of students from foreign countries attending DUT are rising and international cooperation within educational projects is a necessity. To prepare educators for the continuing...

conference paper 2009

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That’s the way we want to learn!” ICT workshop at a primary school

Balch, C. (author), Kooij, R. (author), Leendertse, M. (author)

Education is a key ingredient of any knowledge-based society, and ICT will be a key enabling factor to cope with the new strains on our education system. Recently TNO, the Dutch Organisation for Applied Scientific Research, experimented with different existing ICT technologies in a real-life primary classroom. Our ICT for education project had...

conference paper 2009

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Optimising the Quality of Experience during Channel Zapping: The Impact of Advertisements during Channel Zapping

Kooij, R.E. (author), Klos, V.B. (author), Godana, B.E. (author), Nicolai, F.P. (author), Ahmed, O.K. (author)

Nowadays various digital television services are available. However, the user of these services experiences longer delays than the traditional analog TV while switching from channel to channel. The digital TV operator usually displays a black screen with the channel number during zapping. However, it could be interesting for the TV viewer, if...

journal article 2009

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The Dutch Soccer Team as a Social Network

Kooij, R. (author), Jamakovic, A. (author), Van Kesteren, F. (author), De Koning, T. (author), Theisler, I. (author), Veldhoven, P. (author)

Although being very popular all around the globe, soccer has not received much attention from the scientific community. In this paper we will study the Dutch Soccer Team from the perspective of complex networks. In the DST network every node corresponds to a player that has played an official match for the Dutch Soccer Team. A node is connected...

journal article 2009

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Heterogenous protection in regular and complete bi-partite networks

Omic, J.S. (author), Kooij, R.E. (author), Van Mieghem, P. (author)

We examine the influence of heterogeneous curing rates for a SIS model, used for malware spreading on the Internet, information dissemination in unreliable networks, and propagation of failures in networks. The topology structures considered are the regular graph which represents the homogenous network structures and the complete bi-partite...

conference paper 2009

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A New Metric for Robustness with Respect to Virus Spread (Work in Progress)

Kooij, R.E. (author), Schumm, P. (author), Scoglio, C. (author), Youssef, M. (author)

The robustness of a network is depending on the type of attack we are considering. In this paper we focus on the spread of viruses on networks. It is common practice to use the epidemic threshold as a measure for robustness. Because the epidemic threshold is inversely proportional to the largest eigenvalue of the adjacency matrix, it seems easy...

conference paper 2009

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Impact of Advertisements during Channel Zapping on Quality of Experience

Godana, B.E. (author), Kooij, R.E. (author), Ahmed, O.K. (author)

Nowadays various digital television services are available. However, the user of these services experiences longer delays than the traditional analog TV while switching from channel to channel. The digital TV operator usually displays a black screen with the channel number during zapping. However, it could be interesting for the TV viewer, if...

conference paper 2009

document

Virus Spread in Networks

Van Mieghem, P. (author), Omic, J. (author), Kooij, R. (author)

journal article 2009

document

Model validation of channel zapping quality

Kooij, R. (author), Nicolai, F. (author), Ahmed, K. (author), Brunnström, K. (author)

In an earlier paper we showed, that perceived quality of channel zapping is related to the perceived quality of download time of web browsing, as suggested by ITU-T Rec.G.1030. We showed this by performing subjective tests resulting in an excellent fit with a 0.99 correlation. This was what we call a lean forward experiment and gave the rule of...

conference paper 2009

document

Model validation of channel zapping quality

Kooij, R.E. (author), Nicolai, F. (author), Ahmed, O.K. (author), Brunnström, K. (author)

In an earlier paper we showed, that perceived quality of channel zapping is related to the perceived quality of download time of web browsing, as suggested by ITU-T Rec.G.1030. We showed this by performing subjective tests resulting in an excellent fit with a 0.99 correlation. This was what we call a lean forward experiment and gave the rule of...

conference paper 2009

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ELASTICITY: Topological Characterization of Robustness in Complex Networks

Sydney, A. (author), Schumm, P. (author), Scoglio, C. (author), Kooij, R.E. (author)

conference paper 2008

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On the Quality of Experience of SopCast

Fallica, B., Lu, Y. (author), Kuipers, F.A. (author), Kooij, R. (author), Van Mieghem, P. (author)

conference paper 2008

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Quantifying the Quality of Service of Streaming Media in Differentiated Services Networks

Agrawal, D.K. (author), Kleiberg, T. (author), Papp, S. (author), Kooij, R.E. (author), Van Mieghem, P. (author)

Quality of Service (QoS) support in the current internet is indispensable because of QoS-sensitive real-time applications such as Voice-over-IP, IP-TV, video conferencing, online gaming etc. Since the introduction of the Differentiated Services (Diff-Serv) architecture there has been considerable work reported in literature on its performance...

conference paper 2007

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Of MOS and men: Bridging the gap between objective and subjective quality measurements in mobile TV

De Koning, T.C.M. (author), Veldhoven, P. (author), Knoche, H. (author), Kooij, R.E. (author)

In this paper we explore the relation between subjective and objective measures of video quality. We computed objective MOS values from video clips using the video quality measuring tool VQM and compared it to the clips’ subjective Acceptability scores. Using the ITU defined mapping (M2G) from MOS to binary Good or Better (GoB) values, we...

conference paper 2007