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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 ▲]

Detailed reference viewed: 295 (16 UL)
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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)

Detailed reference viewed: 390 (9 UL)
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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: 262 (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: 243 (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: 334 (7 UL)
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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: 291 (5 UL)
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See detailShaping Pulses to Control Bistable Monotone Systems Using Koopman Operator
Sootla, Aivar; Mauroy, Alexandre UL; Goncalves, Jorge UL

in 10th IFAC Symposium on Nonlinear Control Systems (2016, August)

In this paper, we further develop a recently proposed control method to switch a bistable system between its steady states using temporal pulses. The motivation for using pulses comes from biomedical and ... [more ▼]

In this paper, we further develop a recently proposed control method to switch a bistable system between its steady states using temporal pulses. The motivation for using pulses comes from biomedical and biological applications (e.g. synthetic biology), where it is generally di cult to build feedback control systems due to technical limitations in sensing and actuation. The original framework was derived for monotone systems and all the extensions relied on monotone systems theory. In contrast, we introduce the concept of switching function which is related to eigenfunctions of the so-called Koopman operator subject to a xed control pulse. Using the level sets of the switching function we can (i) compute the set of all pulses that drive the system toward the steady state in a synchronous way and (ii) estimate the time needed by the ow to reach an epsilon neighborhood of the target steady state. Additionally, we show that for monotone systems the switching function is also monotone in some sense, a property that can yield e cient algorithms to compute it. This observation recovers and further extends the results of the original framework, which we illustrate on numerical examples inspired by biological applications. [less ▲]

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See detailA Shared Basis for Functional Modelling
Eisenbart, Boris UL; Gericke, Kilian UL; Blessing, Lucienne UL

in Proceedings of Norddesign 2012 (2012)

The presented research aims at contributing to a better understanding of the diverse functional modelling approaches proposed across disciplines, often involving more than one function model. The paper ... [more ▼]

The presented research aims at contributing to a better understanding of the diverse functional modelling approaches proposed across disciplines, often involving more than one function model. The paper presents a review of 41 systematic design approaches from different disciplines, analysing what is addressed by functional modelling at which point in the proposed development process, i.e. in which sequence, if any. The analysis aims at deriving potential commonalities across disciplines, which could support the development of an integrative functional modelling approach. Finally, the results of the analysis are discussed, concluding that while there seems to be no shared sequence in functional modelling across disciplines, a common base can be derived, with regard to what is prominently addressed by functional modelling in the different disciplines. [less ▲]

Detailed reference viewed: 67 (4 UL)
See detailA short course on The Extended Finite Element Method
Fries, Thomas-Peter; Zilian, Andreas UL

Book published by CES University of Luxembourg - 1 (2013)

Detailed reference viewed: 286 (21 UL)
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See detailA short Survey on the Cyber Security in Control Systems
Bezzaoucha, Souad UL; Voos, Holger UL

Scientific Conference (2020, July)

In the present survey paper, we give a short, yet exhaustive state-of-the-art about the cyber-security applied to control systems, especially the event-based strategy. Indeed, in the past few years, due ... [more ▼]

In the present survey paper, we give a short, yet exhaustive state-of-the-art about the cyber-security applied to control systems, especially the event-based strategy. Indeed, in the past few years, due to a highest degree of connectivity in modern systems, new related control-specific cyber-physical systems security challengesarise and novel approaches integrating the cyber aspect are developed.Our goal in this paper is then to provide an overview of attack-modeling and security analysis approaches in recent works thatexplore networked control systems subject to cyber-attacks attacks. To this end, we look at the control, estimation, and modeling problems. [less ▲]

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See detailSignal control strategies in day-to-day dynamic process of combined traffic assignment and control
Huang, Wei; Viti, Francesco UL; Tampere, Chris M.J.

Scientific Conference (2013)

Detailed reference viewed: 80 (3 UL)
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See detailSignal phase and timing (spat) for cooperative public transport priority measures
Seredynski, Marcin; Viti, Francesco UL; Khadraoui, Djamel

Scientific Conference (2015, October)

Detailed reference viewed: 65 (1 UL)
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See detailSimple and extensible plate and shell finite element models through automatic code generation tools
Hale, Jack UL; Brunetti, Matteo; Bordas, Stéphane UL et al

in Computers & Structures (2018), 209

A large number of advanced finite element shell formulations have been developed, but their adoption is hindered by complexities of transforming mathematical formulations into computer code. Furthermore ... [more ▼]

A large number of advanced finite element shell formulations have been developed, but their adoption is hindered by complexities of transforming mathematical formulations into computer code. Furthermore, it is often not straightforward to adapt existing implementations to emerging frontier problems in thin structural mechanics including nonlinear material behaviour, complex microstructures, multi-physical couplings, or active materials. We show that by using a high-level mathematical modelling strategy and automatic code generation tools, a wide range of advanced plate and shell finite element models can be generated easily and efficiently, including: the linear and non-linear geometrically exact Naghdi shell models, the Marguerre-von K ́arm ́an shallow shell model, and the Reissner-Mindlin plate model. To solve shear and membrane-locking issues, we use: a novel re-interpretation of the Mixed Interpolation of Tensorial Component (MITC) procedure as a mixed-hybridisable finite element method, and a high polynomial order Partial Selective Reduced Integration (PSRI) method. The effectiveness of these approaches and the ease of writing solvers is illustrated through a large set of verification tests and demo codes, collected in an open-source library, FEniCS-Shells, that extends the FEniCS Project finite element problem solving environment. [less ▲]

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See detailA simple and robust computational homogenization approach for heterogeneous particulate composites
Bansal, Manik; Singh, I.V.; Patil, R.U. et al

in Computer Methods in Applied Mechanics and Engineering (2019), 349

In this article, a computationally efficient multi-split MsXFEM is proposed to evaluate the elastic properties of heterogeneous materials. The multi-split MsXFEM is the combination of multi-split XFEM ... [more ▼]

In this article, a computationally efficient multi-split MsXFEM is proposed to evaluate the elastic properties of heterogeneous materials. The multi-split MsXFEM is the combination of multi-split XFEM with multiscale finite element methods (MsFEM). The multi-split XFEM is capable to model multiple discontinuities in a single element which leads to reduction in the number of mesh elements, whereas MsFEM helps in reducing the computational time. Strain energy based homogenization has been implemented on an RVE (having volume fraction of heterogeneities up to 50%) for evaluating the elastic properties. From macro-element size analysis, we estimate that the RVE edge length must be 5 times the edge length of the macro-element. The directional analysis has been performed to verify the isotropic behavior of the material, whereas contrast analysis has been done to check the numerical accuracy of the proposed scheme. A level set correction (LSC) based on higher order shape functions has been proposed to reduce mapping errors of level set values. It is also observed that multi-split MsXFEM is about 16 times computationally more efficient than MsXFEM for 50% volume of heterogeneities. [less ▲]

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See detailA simple and robust three-dimensional cracking-particle method without enrichment
Rabczuk, T.; Zi, G.; Bordas, Stéphane UL et al

in Computer Methods in Applied Mechanics & Engineering (2010), 199(37-40), 2437-2455

A new robust and efficient approach for modeling discrete cracks in meshfree methods is described. The method is motivated by the cracking-particle method (Rabczuk T., Belytschko T., International Journal ... [more ▼]

A new robust and efficient approach for modeling discrete cracks in meshfree methods is described. The method is motivated by the cracking-particle method (Rabczuk T., Belytschko T., International Journal for Numerical Methods in Engineering, 2004) where the crack is modeled by a set of cracked segments. However, in contrast to the above mentioned paper, we do not introduce additional unknowns in the variational formulation to capture the displacement discontinuity. Instead, the crack is modeled by splitting particles located on opposite sides of the associated crack segments and we make use of the visibility method in order to describe the crack kinematics. We apply this method to several two- and three-dimensional problems in statics and dynamics and show through several numerical examples that the method does not show any "mesh" orientation bias. © 2010 Elsevier B.V. [less ▲]

Detailed reference viewed: 125 (0 UL)