1,721,032 research outputs found
Time‐Varying Input‐Output Inoperability Model
No full textRepresenting interdependent critical infrastructures is mandatory for implementing protection policies and strategies. Among the several interdependency models provided over the years, the input-output inoperability model (IIM) has attracted widespread attention due to its simplicity and compactness. Such a model can emphasize cascading effects induced in a complex scenario by dependencies and interdependencies; however, the model is typically set up based on economic data, and the stationary assumption greatly reduces the applicability of the framework. These aspects are crude approximations due to the intrinsic limits of the methodology. Indeed, in modeling realistic scenarios, the coupling of different infrastructures and sectors is expected to increase with outage duration. In this paper, a different formulation of the IIM is proposed where time-varying interdependency coefficients are considered. Such coefficients are defined to explicitly account for the severity and duration of negative phenomena. Some interesting results are obtained from a complex case study including several infrastructures in Italy, emphasizing the features of the proposed methodology. The proposed framework, based directly on operator experience, captures the behaviors induced by the various backup strategies
Simultaneous localization and routing in sensor networks using shadow edges
No full textIn the last decade, Wireless Sensor Networks (WSN) have been adopted in a wide range of industrial and consumer applications to perform various monitoring tasks such as search, rescue, disaster relief, target tracking and smart environments control. In many such tasks, node localization is inherently one of the system parameters. Node localization is required to gain spatial awareness of the supervised area. In this work a simultaneous localization and routing algorithm is proposed. The localization is obtained by a ranging technique, exploiting network topology provided by the routing algorithm to reduce the network signaling communication, which is the most power-consuming operation in WSN, as much as possible. To this end, Shadow Edges, a novel class of links, is considered to take into account the lack of communication among nodes
Sensor Networks Localization: Extending Trilateration via Shadow Edges
Full text linkDistance-based network localization is known to have solution, in general, if the network is globally rigid. In this technical note we relax this condition with reference to unit disk graphs. To this end, shadow edges are introduced to model the fact that selected nodes are not able to sense each other. We provide a localization algorithm based on such edges and a necessary and sufficient localizability condition. We also investigate the relation between the proposed approach and trilateration, showing from both a theoretical and empirical perspective that shadow edge localization succeeds also when trilateration fails
Critical clusters in interdependent economic sectors: A data-driven spectral clustering analysis
Full text linkIn this paper we develop a data-driven hierarchical clustering methodology to group the economic sectors of a country in order to highlight strongly coupled groups that are weakly coupled with other groups. Specifically, we consider an input-output representation of the coupling among the sectors and we interpret the relation among sectors as a directed graph; then we recursively apply the spectral clustering methodology over the graph, without a priori information on the number of groups that have to be obtained. In order to do this, we resort to the eigengap criterion, where a suitable number of groups is selected automatically based on the intensity and structure of the coupling among the sectors. We validate the proposed methodology considering a case study for Italy, inspecting how the coupling among clusters and sectors changes from the year 1995 to 2011, showing that in the years the Italian structure underwent deep changes, becoming more and more interdependent, i.e., a large part of the economy has become tightly coupled
Identifying critical infrastructure clusters via spectral analysis
No full textIn this paper we discuss how to identify groups composed of strictly dependent infrastructures or subsystems. To this end we suggest the use of spectral clustering methodologies, which allow to partition a set of elements in groups with strong intra-group connections and loose inter-group coupling. Moreover, the methodology allows to calculate in an automatic way a suitable number of subsets in which the network can be decomposed. The method has been applied to the Italian situation to identify, on the base of the Inoperability Input-Output model, which are the most relevant set of infrastructures. The same approach has been applied also to partition in a suitable way a network, as illustrated with respect to the IEEE 118 Bus Test Case electric grid
High-speed intrusion detection in support of critical infrastructure protection
No full textNowadays telecommunication network plays a fundamental role in the management of critical infrastructures since it is largely used to transmit control information among the different elements composing the architecture of a critical system. The health of a networked system strictly depends on the security mechanisms that are implemented in order to assure the correct operation of the communication network. For this reason, the adoption of an effective network security strategy is seen as an important and necessary task of a global methodology for critical infrastructure protection. In this paper we present a two-fold contribution. First, we present a distributed architecture aiming to secure the communication network upon which the critical infrastructure relies. Such architecture is composed of an intrusion detection system which is built on top of a customizable flow monitor. Second, we propose an innovative method to extrapolate real-time information about user behavior from network traffic. Such method consists in monitoring traffic flows at different levels of granularity in order to discover ongoing attacks
Augmenting rescuer safety using wireless sensor networks
No full textLocalization and tracking are fundamental features in emergency response operations, where the mission leader needs to be aware of the team location. This paper addresses the localization for rescuers by exploiting wireless sensor networks embedded in the environment. Specifically, a pre-deployed network is considered and a localization algorithm is designed to find the location of the node and to track the rescuers cooperatively. Nodes estimate their own positions, while rescuers improve and augment their location awareness during mission by navigating across via points suggested by the network, thus improving the overall localizability. Experimental results show the effectiveness of the approach
- …
