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See detailRobust Traffic Anomaly Detection with Principal Component Pursuit
Abdelkefi, Atef; Jiang, Yuming; Wang, Wei UL et al

in Proceedings of the ACM CoNEXT Student Workshop (2010)

Principal component analysis (PCA) is a statistical technique that has been used for data analysis and dimensionality reduction. It was introduced as a network traffic anomaly detection technique firstly ... [more ▼]

Principal component analysis (PCA) is a statistical technique that has been used for data analysis and dimensionality reduction. It was introduced as a network traffic anomaly detection technique firstly in [1]. Since then, a lot of research attention has been received, which results in an extensive analysis and several extensions. In [2], the sensitivity of PCA to its tuning parameters, such as the dimension of the low-rank subspace and the detection threshold, on traffic anomaly detection was indicated. However, no explanation on the underlying reasons of the problem was given in [2]. In [3], further investigation on the PCA sensitivity was conducted and it was found that the PCA sensitivity comes from the inability of PCA to detect temporal correlations. Based on this finding, an extension of PCA to Kalman-Loeve expansion (KLE) was proposed in [3]. While KLE shows slight improvement, it still exhibits similar sensitivity issue since a new tuning parameter called temporal correlation range was introduced. Recently, in [4], additional effort was paid to illustrate the PCA-poisoning problem. To underline this problem, an evading strategy called Boiled-Frog was proposed which adds a high fraction of outliers to the traffic. To defend against this, the authors employed a more robust version of PCA called PCA-GRID. While PCA-GRID shows performance improvement regarding the robustness to the outliers, it experiences a high sensitivity to the threshold estimate and the k-dimensional subspace that maximizes the dispersion of the data. The purpose of this work is to consider another technique to address the PCA poisoning problems to provide robust traffic anomaly detection: The Principal Component Pursuit. [less ▲]

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See detailRobustness analysis of cellular systems for in silico drug discovery
Perumal, Thanneer Malai UL; Wu, Y.; Gunawan, R.

Scientific Conference (2008)

Detailed reference viewed: 80 (1 UL)
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See detailThe role of microscale solid matrix compressibility on the mechanical behaviour of poroelastic materials
Dehghani, Hamidreza UL; Noll, Isabelle; Penta, Raimondo et al

in European Journal of Mechanics. A, Solids (2020), 83

We present the macroscale three-dimensional numerical solution of anisotropic Biot's poroelasticity, with coefficients derived from a micromechanical analysis as prescribed by the asymptotic ... [more ▼]

We present the macroscale three-dimensional numerical solution of anisotropic Biot's poroelasticity, with coefficients derived from a micromechanical analysis as prescribed by the asymptotic homogenisation technique. The system of partial differential equations (PDEs) is discretised by finite elements, exploiting a formal analogy with the fully coupled thermal displacement systems of PDEs implemented in the commercial software Abaqus. The robustness of our computational framework is confirmed by comparison with the well-known analytical solution of the one-dimensional Therzaghi's consolidation problem. We then perform three-dimensional numerical simulations of the model in a sphere (representing a biological tissue) by applying a given constant pressure in the cavity. We investigate how the macroscale radial displacements (as well as pressures) profiles are affected by the microscale solid matrix compressibility (MSMC). Our results suggest that the role of the MSMC on the macroscale displacements becomes more and more prominent by increasing the length of the time interval during which the constant pressure is applied. As such, we suggest that parameter estimation based on techniques such as poroelastography (which are commonly used in the context of biological tissues, such as the brain, as well as solid tumours) should allow for a sufficiently long time in order to give a more accurate estimation of the mechanical properties of tissues. [less ▲]

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See detailS-GHOST: Un modèle d'auto-organisation de l'étalement urbain et du réseau de transport
Caruso, Geoffrey UL; Cavailhès, Jean; Frankhauser, Pierre et al

in Antoni, Jean-Philippe (Ed.) Modéliser la ville: formes urbaines et politiques de transport (2011)

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See detailSa-TikZ: a library to draw switching architectures
Fiandrino, Claudio UL

in Ars TeXnica (2013), 15

The article illustrates how it is possible to draw some types of switching architectures in a simple manner. The Sa-TikZ library provides not only the keys devoted to the drawing part, but also the keys ... [more ▼]

The article illustrates how it is possible to draw some types of switching architectures in a simple manner. The Sa-TikZ library provides not only the keys devoted to the drawing part, but also the keys devoted to customize the aspect of the architectures in the spirit of the TikZ syntax. [less ▲]

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See detailSafer UAV Piloting: A Robust Sense-and-Avoid Solution for Remotely Piloted Quadrotor UAVs in Complex Environments
Wang, Min UL; Voos, Holger UL

in Safer UAV Piloting: A Robust Sense-and-Avoid Solution for Remotely Piloted Quadrotor UAVs in Complex Environments (2019, December)

Current commercial UAVs are to a large extent remotely piloted by amateur human pilots. Due to lack of teleoperation experience or skills, they often drive the UAVs into collision. Therefore, in order to ... [more ▼]

Current commercial UAVs are to a large extent remotely piloted by amateur human pilots. Due to lack of teleoperation experience or skills, they often drive the UAVs into collision. Therefore, in order to ensure safety of the UAV as well as its surroundings, it is necessary for the UAV to boast the capability of detecting emergency situation and acting on its own when facing imminent threat. However, the majority of UAVs currently available in the market are not equipped with such capability. To fill in the gap, in this paper we present a complete sense-and-avoid solution for assisting unskilled pilots in ensuring a safe flight. Particularly, we propose a novel nonlinear vehicle control system which takes into account of sensor characteristics, an emergency evaluation policy and a novel optimization-based avoidance control strategy. The effectiveness of the proposed approach is demonstrated and validated in simulation with multiple moving objects. [less ▲]

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See detailScalable Gaussian Process Inference with Finite-data Mean and Variance Guarantees
Huggins, Jonathan; Campbell, Trevor; Kasprzak, Mikolaj UL et al

in Proceedings of the 22nd International Conference on Artificial Intelligence and Statistics (AISTATS) 2019 (2019)

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See detailSecure and Reliable Clustering in Wireless Sensor Networks: A Critical Survey
Schaffer, Peter UL; Farkas, Károly; Horváth, Ádám et al

in Computer Networks (2012), 56(11), 27262741

In the past few years, research interest has been increased towards wireless sensor networks (WSNs) and their application in both the military and civil domains. To support scalability in WSNs and ... [more ▼]

In the past few years, research interest has been increased towards wireless sensor networks (WSNs) and their application in both the military and civil domains. To support scalability in WSNs and increase network lifetime, nodes are often grouped into disjoint clusters. However, secure and reliable clustering, which is critical in WSNs deployed in hostile environments, has gained modest attention so far or has been limited only to fault tolerance. In this paper, we review the state-of-the-art of clustering protocols in WSNs with special emphasis on security and reliability issues. First, we define a taxonomy of security and reliability for cluster head election and clustering in WSNs. Then, we describe and analyze the most relevant secure and reliable clustering protocols. Finally, we propose countermeasures against typical attacks and show how they improve the discussed protocols. [less ▲]

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See detail(Semi-) Pervasive Gaming Educational and Entertainment Facilities via Interactive Video-to-Video Communication over the Internet, for Museum Exhibits
Chochliouros, Ioannis; McCall, Roderick UL; Popleteev, Andrei UL et al

in Papadopoulos, Harris; Andreou, Andreass; Iliadis, Lazaros (Eds.) et al Artificial Intelligence Applications and Innovations (2013)

Based upon the core concept of the LiveCity Project we focus on the specific City Cultural Experiences v2v Pilot,designed to allow for visitors at two defined locations to interact with one another in a ... [more ▼]

Based upon the core concept of the LiveCity Project we focus on the specific City Cultural Experiences v2v Pilot,designed to allow for visitors at two defined locations to interact with one another in a joint experience and to get educational/entertainment benefits, originating directly from the museum content delivery. We discuss a set of semi-pervasive games (the so-called “Twin Cities”games) which are designed to bring people together at remotely twinned locations through the use of video-to-video communication and multitouch interaction. We also present an early classification of video-to-video (v2v) interaction games that is designed to inform designers about the potential of such technologies. We classify them as: using video for awareness and communication, interacting with video and video as a game. [less ▲]

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See detailSemi-global analysis of relay feedback systems
Goncalves, Jorge UL; Megretski, A.; Dahleh, M. A.

in Proceedings of the 37th IEEE Conference on Decision and Control (1998)

This paper presents semi-global sufficient stability conditions of limit cycles for relay feedback systems. Local stability conditions exist. These are based on analyzing the linear part of the Poincare ... [more ▼]

This paper presents semi-global sufficient stability conditions of limit cycles for relay feedback systems. Local stability conditions exist. These are based on analyzing the linear part of the Poincare map. We know that when a certain limit cycle satisfies those local conditions, a neighborhood around the limit cycle exists such that any trajectory starting in this neighborhood converges to the limit cycle as time goes to infinity. However, tools to characterize this neighborhood do not exist. In this work, we present conditions, in the form of linear matrix inequalities (LMI), that guarantee the stability of a limit cycle in a reasonably large set around it. These results differ from previous local results as they take into account the high order terms of the Poincare map. [less ▲]

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See detailSensitivity Analysis and Shape Optimisation through a T-spline Isogeometric Boundary Element Method
Lian, Haojie; Simpson, Robert; Bordas, Stéphane UL

Scientific Conference (2013, March 25)

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See detailSensitivity Analysis and Shape Optimisation through a T-spline Isogeometric Boundary Element Method
Lian, Haojie; Simpson, Robert; Bordas, Stéphane UL

Scientific Conference (2013, March)

Detailed reference viewed: 307 (1 UL)
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See detailSensitivity analysis and shape optimisation with the isogeometric boundary element methods
Lian, Haojie; Simpson, Robert; Bordas, Stéphane UL

Scientific Conference (2012, March 27)

Detailed reference viewed: 294 (5 UL)
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See detailSensitivity analysis and shape optimization using isogeomgetric boundary element methods
Lian, Haojie; Simpson, Robert; Bordas, Stéphane UL

Scientific Conference (2014, July)

Detailed reference viewed: 396 (7 UL)
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See detailSensitivity Analysis on Regularity Based Driver Advisory Systems
Laskaris, Georgios; Seredynski, Marcin; Viti, Francesco UL

in 2020 IEEE 23rd International Conference on Intelligent Transportation Systems (ITSC) (2020, December)

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See detailSensitivity Analysis on Regularity Based Driver Advisory Systems
Laskaris, Georgios; Seredynski, Marcin; Viti, Francesco UL

Scientific Conference (2021, February)

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See detailA sensitivity-based approach for adaptive decomposition of anticipatory network traffic control
Rinaldi, Marco UL; Himpe, W.; Tampère, C. M. J.

in Transportation Research. Part C : Emerging Technologies (2016), 66

Anticipatory optimal network control is defined as the problem of determining the set of control actions that minimizes a network-wide objective function. This not only takes into account local ... [more ▼]

Anticipatory optimal network control is defined as the problem of determining the set of control actions that minimizes a network-wide objective function. This not only takes into account local consequences on the propagation of flows, but also the global network-wide routing behavior of the users. Such an objective function is, in general, defined in a centralized setting, as knowledge regarding the whole network is needed to correctly compute it. Reaching a level of centralization sufficient to attain network-wide control objectives is however rarely realistic in practice. Multiple authorities are influencing different portions the network, separated either hierarchically or geographically. The distributed nature of networks and traffic directly influences the complexity of the anticipatory control problem. This is our motivation for this work, in which we introduce a decomposition mechanism for the global anticipatory network traffic control problem, based on dynamic clustering of traffic controllers. Rather than solving the full centralized problem, or blindly performing a full controller-wise decomposition, this technique allows recognizing when and which controllers should be grouped in clusters, and when, instead, these can be optimized separately. The practical relevance with respect to our motivation is that our approach allows identification of those network traffic conditions in which multiple actors need to actively coordinate their actions, or when unilateral action suffices for still approximating global optimality. This clustering procedure is based on well-known algebraic and statistical tools that exploit the network's sensitivity to control and its structure to deduce coupling behavior. We devise several case studies in order to assess our newly introduced procedure's performances, in comparison with fully decomposed and fully centralized anticipatory optimal network control, and show that our approach is able to outperform both centralized and decomposed procedures. © 2016 Elsevier Ltd. [less ▲]

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See detailSerge Abiteboul, au cœur des données
Schafer, Valerie UL

in Technique et Science Informatiques (2014)

Des bases de données au « data déluge » actuel, Serge Abiteboul se passionne depuis plus de trente ans pour un domaine qui ne cesse d’évoluer et de nous confronter à de nouveaux défis, techniques, mais ... [more ▼]

Des bases de données au « data déluge » actuel, Serge Abiteboul se passionne depuis plus de trente ans pour un domaine qui ne cesse d’évoluer et de nous confronter à de nouveaux défis, techniques, mais aussi sociétaux. Il a reçu en 2013 le prix Milner de la Royal Society et vient d’achever le projet Webdam sur la gestion des données, pour lequel il avait été lauréat en 2008 d’une bourse ERC. Membre de l’Académie des Sciences et du Conseil National du Numérique, président du conseil scientifique de la SIF, co-fondateur du blog binaire, Serge Abiteboul, chercheur à Inria, revient sur sa carrière, ses recherches et éclaire pour nous quelques-uns des enjeux que pose aujourd’hui le numérique. [less ▲]

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See detailShape Optimization Directly from CAD: an Isogeometric Boundary Element Approach Using T-splines
Lian, Haojie; Pierre, Kerfriden; Bordas, Stéphane UL

Report (2016)

Detailed reference viewed: 358 (5 UL)