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See detailA Contribution to Cyber-Physical Systems Security: an Event-based Attack-tolerant Control Approach
Bezzaoucha, Souad UL; Voos, Holger UL

in Proceedings of 10th IFAC Symposium on Fault Detection, Supervision and Safety for Technical Processes, SAFEPROCESS 2018 (2018, August 29)

In the present paper, a model-based fault/attack tolerant scheme is proposed to deal with cyber-threats on Cyber Physicals Systems. A common scheme based on observers is designed and a state feedback ... [more ▼]

In the present paper, a model-based fault/attack tolerant scheme is proposed to deal with cyber-threats on Cyber Physicals Systems. A common scheme based on observers is designed and a state feedback control based on an event-triggered framework is given with control synthesis and condition on the switching time. An event-based implementation is proposed in order to achieve novel security strategy. Observer and controller gains are deduced by solving su cient Bilinear Matrix Inequality (BMI) condition. Simulation results on a real-time laboratory three tank system are given to show the attack-tolerant control ability despite data deception attacks on both actuators and sensors. [less ▲]

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See detailTapping the Potential of Diverse Founding Teams for Firm Growth: The Role of New Venture Activities
Tryba, Anne UL; Patzelt, Holger; Breugst, Nicola

Scientific Conference (2018, August)

Although education field diversity in founding teams can be an asset for new ventures, working in diverse teams might also be very challenging. Results from recent research indicate that the nature of ... [more ▼]

Although education field diversity in founding teams can be an asset for new ventures, working in diverse teams might also be very challenging. Results from recent research indicate that the nature of diversity effects can only be revealed by exploring its contingencies. We build on upper echelons theory and argue that a new venture’s early activities are key contingencies influencing to what extent it can exploit the benefits of its founding team’s education field diversity. Using survey data from 103 young cofounded ventures in Luxembourg, this study shows that early planning helps new ventures to tap the potential of their educationally diverse teams and contribute to venture growth. In addition, simultaneous planning and experimentation in the early phase also moderate the relationship between education field diversity and venture growth, such that growth is highest when education field diversity, experimentation and planning are high. [less ▲]

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See detailTest Case Prioritization for Acceptance Testing of Cyber Physical Systems: A Multi-Objective Search-Based Approach
Shin, Seung Yeob UL; Nejati, Shiva UL; Sabetzadeh, Mehrdad UL et al

in Proceedings of the ACM SIGSOFT International Symposium on Software Testing and Analysis (ISSTA'18) (2018, July)

Acceptance testing validates that a system meets its requirements and determines whether it can be sufficiently trusted and put into operation. For cyber physical systems (CPS), acceptance testing is a ... [more ▼]

Acceptance testing validates that a system meets its requirements and determines whether it can be sufficiently trusted and put into operation. For cyber physical systems (CPS), acceptance testing is a hardware-in-the-loop process conducted in a (near-)operational environment. Acceptance testing of a CPS often necessitates that the test cases be prioritized, as there are usually too many scenarios to consider given time constraints. CPS acceptance testing is further complicated by the uncertainty in the environment and the impact of testing on hardware. We propose an automated test case prioritization approach for CPS acceptance testing, accounting for time budget constraints, uncertainty, and hardware damage risks. Our approach is based on multi-objective search, combined with a test case minimization algorithm that eliminates redundant operations from an ordered sequence of test cases. We evaluate our approach on a representative case study from the satellite domain. The results indicate that, compared to test cases that are prioritized manually by satellite engineers, our automated approach more than doubles the number of test cases that fit into a given time frame, while reducing to less than one third the number of operations that entail the risk of damage to key hardware components. [less ▲]

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See detailToward a new model of collaborative problem solving definition and assessment
Stoeffler, K.; Greiff, Samuel UL; Von Davier, A. et al

Scientific Conference (2018, July)

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See detailTowards a multifaceted framework of complex problem solving
Stadler, Matthias UL; Niepel, Christoph UL; Greiff, Samuel UL

Scientific Conference (2018, July)

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See detailInnovations in computer-based assessment
Greiff, Samuel UL

Speeches/Talks (2018)

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See detailIntroducing MaFIN. A dynamic matrices finite state automata test
Kunze, Thiemo UL; Krieger, Florian UL; Stadler, Matthias UL et al

Scientific Conference (2018, July)

Detailed reference viewed: 19 (3 UL)
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See detailDynamic controllers for column synchronization of rotation matrices: a QR-factorization approach
Thunberg, Johan UL; Markdahl, Johan UL; Goncalves, Jorge UL

in Automatica (2018), 93

In the multi-agent systems setting, this paper addresses continuous-time distributed synchronization of columns of rotation matrices. More precisely, k specific columns shall be synchronized and only the ... [more ▼]

In the multi-agent systems setting, this paper addresses continuous-time distributed synchronization of columns of rotation matrices. More precisely, k specific columns shall be synchronized and only the corresponding k columns of the relative rotations between the agents are assumed to be available for the control design. When one specific column is considered, the problem is equivalent to synchronization on the (d-1)-dimensional unit sphere and when all the columns are considered, the problem is equivalent to synchronization on SO(d). We design dynamic control laws for these synchronization problems. The control laws are based on the introduction of auxiliary variables in combination with a QR-factorization approach. The benefit of this QR-factorization approach is that we can decouple the dynamics for the $k$ columns from the remaining d-k ones. Under the control scheme, the closed loop system achieves almost global convergence to synchronization for quasi-strong interaction graph topologies. [less ▲]

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See detailA Decoupling Approach to Design Observers for Polytopic Takagi-Sugeno Models Subject to Unknown Inputs
Bezzaoucha, Souad UL; Voos, Holger UL; Davila, Jorge et al

in Proceedings of the 2018 American Control Conference (2018, June 27)

A decoupling approach for state estimation of nonlinear systems represented in the polytopic Takagi-Sugeno with unmeasurable premise variables subject to unknown inputs is proposed in this paper. The idea ... [more ▼]

A decoupling approach for state estimation of nonlinear systems represented in the polytopic Takagi-Sugeno with unmeasurable premise variables subject to unknown inputs is proposed in this paper. The idea consists in defining a state and unknown input transformations in order to divide the state vector into two parts, a measurable part and an observable one (decoupled from the unknown input). A classical Luenberger observer to estimate the unmeasurable part is then designed and given in terms of Linear Matrix Inequalities (LMIs) conditions. A numerical example is also presented in order to illustrate the proposed approach. [less ▲]

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See detailCyber Security and Vulnerability Analysis of Networked Control System subject to False-Data injection
Gerard, Benjamin; Bezzaoucha, Souad UL; Voos, Holger UL et al

in Proceedings of the 2018 American Control Conference (2018, June 27)

In the present paper, the problem of networked control system (NCS) cyber security is considered. The geometric approach is used to evaluate the security and vulnerability level of the controlled system ... [more ▼]

In the present paper, the problem of networked control system (NCS) cyber security is considered. The geometric approach is used to evaluate the security and vulnerability level of the controlled system. The proposed results are about the so-called false data injection attacks and show how imperfectly known disturbances can be used to perform undetectable, or at least stealthy, attacks that can make the NCS vulnerable to attacks from malicious outsiders. A numerical example is given to illustrate the approach. [less ▲]

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See detailIdentity Processes in Multicultural Antwerp: Report on an Ethnographic - Cross-Cultural Study
Stogianni, Maria UL; Van de Vijver, Fons

Presentation (2018, June 21)

Detailed reference viewed: 28 (2 UL)