A Delphi study to recognize and assess systems of systems vulnerabilities

Context: System of Systems (SoS) is an emerging paradigm by which independent systems collaborate by sharing resources and processes to achieve objectives that they could not achieve on their own. In this context, a number of emergent behaviors may arise that can undermine the security of the constituent systems. Objective: We apply the Delphi method with the aims to improve our understanding of SoS security and related problems, and to investigate their possible causes and remedies. Method: Experts on SoS expressed their opinions and reached consensus in a series of rounds by following a structured questionnaire. Results: The results show that the experts found more consensus in disagreement than in agreement about some SoS characteristics, and on how SoS vulnerabilities could be identified and prevented. Conclusions: From this study we learn that more work is needed to reach a shared understanding of SoS vul nerabilities, and we leverage expert feedback to outline some future research directions.Ministerio de Ciencia, Innovación y Universidades PID2019-105455GB-C3

System of Systems Based Decision-Making for Power Systems Operation

A modern power system is composed of many individual entities collaborating with each other to operate the entire system in a secure and economic manner. These entities may have different owners and operators with their own operating rules and policies, and it complicates the decision-making process in the system. In this work, a system of systems (SoS) engineering framework is presented for optimally operating the modern power systems. The proposed SoS framework defines each entity as an independent system with its own regulations, and the communication and process of information exchange between the systems are discussed. Since the independent systems are working in an interconnected system, the operating condition of one may impact the operating condition of others. According to the independent systems’ characteristics and connection between them, an optimization problem is formulated for each independent system. In order to solve the optimization problem of each system and to optimally operate the entire SoS-based power system, a decentralized decision-making algorithm is developed. Using this algorithm, only a limited amount of information is exchanged among different systems, and the operators of independent systems do not need to exchange all the information, which may be commercially sensitive, with each other. In addition, applying chance-constrained stochastic programming, the impact of uncertain variables, such as renewable generation and load demands, is modeled in the proposed SoS-based decision-making algorithm. The proposed SoS-based decision-making algorithm is applied to find the optimal and secure operating point of an active distribution grid (ADG). This SoS framework models the distribution company (DISCO) and microgrids (MGs) as independent systems having the right to work based on their own operating rules and policies, and it coordinates the DISCO and MGs operating condition. The proposed decision-making algorithm is also performed to solve the security-constrained unit commitment incorporating distributed generations (DGs) located in ADGs. The independent system operator (ISO) and DISCO are modeled as self-governing systems, and competition and collaboration between them are explained according to the SoS framework

A Holistic Approach to Functional Safety for Networked Cyber-Physical Systems

Functional safety is a significant concern in today's networked cyber-physical systems such as connected machines, autonomous vehicles, and intelligent environments. Simulation is a well-known methodology for the assessment of functional safety. Simulation models of networked cyber-physical systems are very heterogeneous relying on digital hardware, analog hardware, and network domains. Current functional safety assessment is mainly focused on digital hardware failures while minor attention is devoted to analog hardware and not at all to the interconnecting network. In this work we believe that in networked cyber-physical systems, the dependability must be verified not only for the nodes in isolation but also by taking into account their interaction through the communication channel. For this reason, this work proposes a holistic methodology for simulation-based safety assessment in which safety mechanisms are tested in a simulation environment reproducing the high-level behavior of digital hardware, analog hardware, and network communication. The methodology relies on three main automatic processes: 1) abstraction of analog models to transform them into system-level descriptions, 2) synthesis of network infrastructures to combine multiple cyber-physical systems, and 3) multi-domain fault injection in digital, analog, and network. Ultimately, the flow produces a homogeneous optimized description written in C++ for fast and reliable simulation which can have many applications. The focus of this thesis is performing extensive fault simulation and evaluating different functional safety metrics, \eg, fault and diagnostic coverage of all the safety mechanisms

Investments under uncertainty in Next Generation Access Networks on the basis of different Regulatory Policies

Οι επενδύσεις στις τηλεπικοινωνίες, και ειδικότερα, τα έργα που αφορούν τον τοπικό βρόχο σχετικά με την εγκατάσταση οπτικών ινών είναι πολύπλοκα εγχειρήματα που απαιτούν την εξέταση διαφορετικών παραμέτρων που αφορούν την περάτωση τους. Παράγοντες όπως η τοπολογία του δικτύου, τα ρυθμιστικά καθεστώτα βάσει των οποίων θα λάβουν χώρα τα συγκεκριμένα έργα και ο τρόπος λειτουργίας της αγοράς έχουν σημαντική επίδραση στον σχεδιασμό των συγκεκριμένων έργων. Σαν συνέπεια, είναι απαραίτητη μια μέθοδος που θα επεξεργάζεται και θα συνθέτει αυτές τις παραμέτρους με τέτοιο τρόπο που να εξάγεται προσεγγιστικά μια συνολική εικόνα για την περάτωση και το τελικό αποτέλεσμα του έργου. Σε αυτή τη διπλωματική εργασία, χρησιμοποιείται η Διευρευνητική Μοντελοποίηση και Ανάλυση σε συνδυασμό με την εξέταση δύο διαφορετικών ρυθμιστικών καθεστώτων, της Ρήτρας Λήξης Ισχύος (Sunset Clause) και της Ρυθμιστικής Διακοπής (Regulatory Holiday) , για την παροχή μιας προσομοίωσης της εξέλιξης μια επένδυσης στα Δίκτυα Πρόσβασης Επόμενης Γενιάς, με βάση οικονομικούς δείκτες της επένδυσης όπως τα κέρδη του κυρίαρχου παρόχου και της αντίστοιχης κοινωνικής ευημερίας.Telecommunications investments and, especially, the local loop projects for the installation of fiber optics are complicated subjects which demand the examination of different parameters that affect their evolution. Factors such as the network topology, the regulatory regimes under which these investments will take place and the way that the market will operate have a significant effect in the design of these projects. As a result, it is necessary a method which will be able to process and compound these parameters in the way that it will produce an approximately complete aspect for the evolution and the final result of the project. In this thesis, Exploratory Modeling and Analysis is used for this purpose in conjunction with two different regulatory regimes, sunset clause and regulatory holiday, to provide a simulation of the evolution of an Next Generation Access Network investment, based on project indices such as incumbent service provider’s profits and the corresponding social welfare

A system of systems framework for the reliability assessment of telecommunications networks

In this paper, a system of systems (SoS) framework for the reliability analysis of telecommunication networks is proposed. In this framework, two hazard analysis techniques, hazard and operability analysis and fault tree analysis, are combined in a hybrid scheme. This is further enhanced using the Bayesian network model along with sensitivity analysis in order to answer complex probability queries and to estimate the impact of residual mishap risks, unknown events, or events that cannot easily be modeled. The SoS emergent behavior is further revealed using exploratory modeling. The proposed SoS framework is applied in the case of a fiber-to-the-curb VDSL telecommunication network. © 2007-2012 IEEE