Gabriele Oliva

Università Campus Bio-Medico di Roma | unicampus ·  Faculty of Engineering

BACKGROUND: The typical reaction strategy to an epidemic involves the implementation of various pharmaceutical (e.g., vaccination) and non-pharmaceutical interventions (e.g., social distancing) to reach the so-called "herd immunity threshold," ensuring that new surges of the epidemic dampen out. AIM: We introduce a novel concept: the "Herd Immunity...

In this paper we focus our attention on an interesting property of linear and time-invariant systems, namely negativizability: a pair (A,C) is negativizable if a gain matrix K exists such that A-KC is negative definite. Notably, in this paper we show that negativizability can be a useful feature for solving distributed estimation and control proble...

COVID-19 has changed the very way we live our lives, from how we learn and work to how we interact. It has also brought a number of challenges including the management of building utilities under such conditions. In fact, during a lockdown, it makes sense to allocate the available resources based on the density of population, e.g., preferring resid...

Objective: A major concern with wearable devices aiming to measure the seismocardiogram (SCG) signal is the variability of SCG waveform with the sensor position and a lack of a standard measurement procedure. We propose a method to optimize sensor positioning based on the similarity among waveforms collected through repeated measurements. Method:...

Relative pairwise comparisons represent the cornerstone for several decision-making methods. Such approaches aim to support complex decision-making situations with multiple alternatives and are essential in order to provide an overall absolute evaluation of the alternatives despite the presence of experts and/or decision-makers with conflicting opi...

In this article, we consider the problem of modifying in a distributed way the transition probabilities of a Markov chain over an undirected graph in order to achieve a desired limiting distribution, while minimizing the variation from the current weights. This problem setting could be used to model a (graph-based) distributed decision-making proce...

Security of distributed consensus algorithms is rapidly becoming a matter of paramount importance. Existing approaches address it by identifying corrupted nodes and deleting them from the network, but this results in the permanent loss of the contribution of these agents even if they return to their proper functionality. In this paper, we consider...

The business continuity of services provided by Critical Infrastructures is vital in order to ensure the security, the economy and the public’s health of a Nation. Delays and bad recovery strategies after disasters or failures can lead to impairing impacts in terms of injury to people, environmental pollution and loss of time, money and resources....

In this paper we address a time-varying quadratic optimization problem over a graph under the assumption that the problem shares the same sparsity pattern as the static graph encoding the undirected network topology over which the multi-agent systems interacts. Notably, this framework allows to effectively model scenarios in which the optimization...

Distributed cooperative multi-agent operations, which are emerging as effective solutions in countless application domains, are prone to eavesdropping by malicious entities due to their exposure on the network. Moreover, in several cases, agents are reluctant to disclose their initial conditions (even to legitimate neighbors) due to their sensitivi...

In this paper, we develop a general Open Multi-Agent Systems (OMAS) framework over undirected graphs where the agents' interaction is, in general, nonlinear, time-varying, and heterogeneous, in that the agents interact with different pairwise interaction rules for each link, possibly nonlinear, which may change over time. In particular, assuming th...

In this article, we introduce a novel optimization formulation able to capture the main aspects of a networked system affected by faults that reduce the efficiency in terms of flow transmission, as well as to optimize response teams in charge of restoring the subsystems from faults. We propose a nonlinear optimization problem based on the max-flow...

In this article, we propose a distributed negotiation framework that allows a set of cooperative agents to find a common ground with their neighbors while attempting to modify their initial opinion by the least possible amount. Based on such a framework, we develop a distributed agreement approach where the effort spent in the local agreement refle...

In this paper, we present a distributed algorithm which implements the k-means algorithm in a distributed fashion for multi-agent systems with directed communication links. The goal of k-means is to partition the network's agents in mutually exclusive sets (groups) such that agents in the same set have (and possibly share) similar information and a...

In this paper, we present a distributed algorithm which implements the $k$-means algorithm in a distributed fashion for multi-agent systems with directed communication links. The goal of $k$-means is to partition the network's agents in mutually exclusive sets (groups) such that agents in the same set have (and possibly share) similar information a...

In this paper we consider a state estimation problem featuring an autonomous linear system and a set of interconnected sensors, each able to measure, in general, different measures and able to acquire their measurements and interact with each other in an asynchronous fashion. In particular, as a first step in the solution of this problem, in this...

The call for integrated management of safety and security (IMSS) derives from intensification of digitalisation development and the increased reliance on information communication technologies (ICT) in high-risk industries, such as the chemical and process industry. This development means tightened interconnectedness between industrial automation a...

The greater availability and accessibility of IoT sensors, data acquisition systems and computer networks, led to the development of distributed control strategies aimed at monitoring and securing of Cyber-Physical Systems (CPS). In this paper, we propose a distributed asynchronous algorithm for the Secure State Reconstruction (SSR) which relies on...

Distributed average consensus is a fundamental feature of multi-agents systems; yet, in several cases agents are reluctant to disclose their initial conditions, e.g., due to their sensitivity about private data. Consequently, ensuring the privacy of such information against honest but curious neighbours becomes a mandatory necessity. In this paper...

In this paper, we consider a distributed computation setting where agents are interconnected by a directed and strongly connected graph and the opinion of each agent is characterized by a convex set in a metric space. Given an initial point and under the assumption that the convex sets have a nonempty intersection, the aim of the agents is to compu...

COVID-19 has got us to face a new situation where, for the lack of ready-to-use vaccines, it is necessary to support vaccination with complex non-pharmaceutical strategies. In this paper, we provide a novel Mixed Integer Nonlinear Programming formulation for fine-grained optimal intervention planning (i.e., at the level of the single day) against n...

In this paper we develop a simple, yet effective, secure communication protocol based on linear algebra that allows messages to be transmitted securely, without the need to encrypt them through computationally demanding approaches or to consider integer-valued plain messages, except during an initialization phase. The scheme is composed by several...

Automatic decision support systems are typically based on objective data and rely on data-driven techniques such as machine learning. Yet, in order to take effective decisions, it is fundamental to incorporate also experience-driven approaches that are able to leverage on the experience of human decision makers and experts. However, there is a need...

In the context of decision making, pairwise comparisons matrices (PCMs) based on a ratio scale are essential for deriving absolute preferences from relative comparisons. Such techniques are based on Subject Matter Experts (SMEs), which express their relative judgements on pairs of alternatives, providing pairwise comparison information, also in the...

Allowing Multi-Agent Systems (MAS) to compute the mode of the agents’ initial values (i.e., the value with largest cardinality) represents a highly valuable building block for the development of complex decision-making tasks, as it allows agents to identify the central tendency of data or to implement majority voting processes while considering cat...

In this paper we propose a load balancing problem formulation where agents cooperate with the aim of simultaneously minimizing both the workload disparity among the agents and the overall workload transfer, under network capacity constraints. Notably, in our computational setting, the network is not just a device for the distributed solution of an...

This paper develops a framework to track the trajectory of a target in 2D by considering a moving ownship able to measure bearing measurements. Notably, the framework allows one to incorporate additional information (e.g., obtained via intelligence) such as knowledge on the fact the target’s trajectory is contained in the intersection of some sets...

The construction of large infrastructures (e.g., railways, gas pipelines or power grids) is increasingly facing widespread and violent opposition of radical environmentalist and ideological groups. Therefore, it is necessary to consider also the risk related to violent opposition actions when selecting construction sites. However, the classical par...

Near real-time monitoring and control of critical infrastructure is essential for the operation and management of cities in a world that is, today, more complex and interconnected than ever. Such an infrastructure can be represented as complex networks an some of their related indices and statistics, many of them based on the shortest paths, play a...

From an engineering point of view, the survivability of a system is defined as its ability to continue to operate despite a natural or human-made disturbance; for example a serious mechanical fault, a human error, or a malicious cyber or physical attack. In the context of critical infrastructures, due to their relevance for the public wellness, it...

In this paper we propose an optimal Man-In-The-Middle attack strategy to maliciously manipulate information transmitted from the field to a centralized control unit. The aim of the attacker is to significantly deviate the system’s behavior from its nominal trajectory and, at the same time, avoid that thew attack can be recognized. Specifically, we...

Incomplete pairwise comparison matrices offer a natural way of expressing preferences in decision-making processes. Although ordinal information is crucial, there is a bias in the literature: cardinal models dominate. Ordinal models usually yield nonunique solutions; therefore, an approach blending ordinal and cardinal information is needed. In thi...

Measures of node centrality that describe the importance of a node within a network are crucial for understanding the behavior of social networks and graphs. In this article, we address the problems of distributed estimation and control of node centrality in undirected graphs with asymmetric weight values. In particular, we focus our attention on...

This paper provides an implementation of the C-means algorithm in an asynchronous and distributed fashion; specifically, we consider a network of agents, each provided with a piece of information (e.g., data acquired via sensors) and we partition the agents in not mutually exclusive sets such that agents in the same set have similar information; mo...

Spotting criticalities in Critical Infrastructure networks is a crucial task in order to implement effective protection strategies against exogenous or malicious events. Yet, most of the approaches in the literature focus on specific aspects (e.g., presence of hubs, minimum paths) and there is a need to identify tradeoffs among importance metrics t...

Assessing critical infrastructure vulnerabilities is paramount to arrange efficient plans for their protection. Critical infrastructures are network-based systems hence, they are composed of nodes and edges. The literature shows that node criticality, which is the focus of this paper, can be addressed from different metric-based perspectives (e.g.,...

The security of critical infrastructures is of paramount importance nowadays due to the growing complexity of components and applications. This paper collects the contributions to the industry dissemination session within the 14th International Conference on Critical Information Infrastructures Security (CRITIS 2019). As such, it provides an overvi...

In this paper we develop a novel approach to identify the best policy to allocate protection resources to raise the overall network robustness to node disruption. The proposed methodology is based on the identification of the most critical elements of the network in terms of their connectivity contribution to the entire system. The definition of th...

The security of critical infrastructures is of a paramount importance nowadays due to the growing complexity of components and applications. This paper collects the contributions to the industry dissemination session within the 14th International Conference on Critical Information Infrastructures Security (CRITIS 2019). As such, it provides an over...

This paper proposes an asynchronous gossip framework where agents move according to independent random walks over a location graph and interactions may occur only when two agents share the same location. Our goal is to investigate how average consensus may be achieved when agents’ motion occurs over a set of discrete locations with topological cons...

Following the Industry/Hospital 4.0 paradigm, the cost and effectiveness of the services offered by a modern Hospital can be dramatically improved by resorting to technology and by putting the patients (and the medical practitioners) at the center, thus improving their care experience (and work time), improving efficiency and paying more attention...

The Industrial Internet of Things (IIoT) consists of the pervasive application of the IoT paradigm in conjunction with analytics and artificial intelligence (AI) in industrial scenarios. Industry 4.0 (I4.0) extends further the IIoT model with the inclusion of robotics and automation, whereas Hospital 4.0 (H4.0) is the application of the I4.0 paradi...

The aim of the sparse analytic hierarchy process (SAHP) problem is to rank a set of alternatives based on their utility/importance; this task is accomplished by asking human decision-makers to compare selected pairs of alternatives and to specify relative preference information, in the form of ratios of utilities. However, such an information is of...

Incomplete pairwise comparison matrices offer a natural way of expressing preferences in decision making processes. Although ordinal information is crucial, there is a bias in the literature: cardinal models dominate. Ordinal models usually yield non-unique solutions; therefore, an approach blending ordinal and cardinal information is needed. In th...

Measures of node centrality that describe the importance of a node within a network are crucial for understanding the behavior of social networks and graphs. In this paper, we address the problems of distributed estimation and control of node centrality in undirected graphs with asymmetric weight values. In particular, we focus our attention on $\a...

The flow network balancing problem, i.e., the problem of balancing the incoming and outgoing flows for each vertex of a directed graph, has been widely investigated with several distributed solutions being proposed in recent years. Flow balancing is crucial in several application domains, ranging from water and traffic networks to complex network s...

Seveso III Directive (2012/18/EU) requires operators to demonstrate that they have identified major accident hazards and scenarios, and that they have implemented adequate actions to prevent such accidents. Safety reports issued under the Seveso Directive specifically address accident scenarios caused by technical or human failures. Scenarios cause...

Most of classical decision making processes aim at selecting the “best” alternative or at ranking alternatives based on the opinions of decision makers. Often, such a process occurs among people (experts or decision makers) who are expected to achieve some shared consensus in ranking the alternatives. However, this is not likely to happen (especial...

The reliability of the localization of Wireless Sensor Networks in presence of errors or malicious data alteration is a challenging research topic: recently, several studies have been carried out to identify, remove or neglect the faulted/malicious nodes. This paper addresses the capability of a network, composed of range-capable nodes and anchor n...

In this paper, we review some of the main discrete and finite time average consensus implementations in the literature, discussing their strengths and shortcomings from a theoretical and empirical point of view. In particular, we compare the computational characteristics of the different algorithms, their behaviour considering different underlying...

In this paper we develop novel vulnerability metrics for interdependent critical infrastructures or economic sectors based on the concept of controllability. Specifically, we consider the Input-Output Inoperability Model, that represents the dynamics of the dependencies and interdependencies among infrastructures or sectors during an adverse event...

In this paper we consider a scenario where a set of agents, interconnected by a network topology, aim at computing an estimate of their own utility, importance or value, based on pairwise relative information having heterogeneous nature. In more detail, the agents are able to measure the difference between their value and the value of some their ne...

In this paper, we provide a maritime counter-piracy framework to represent the strategies put in place and the interaction between a set of actors (patrollers and attackers) in a wide maritime scenario. Specifically, we model the interaction between patrollers and attackers in terms of a Stackelberg leader–follower game. With respect to the previou...

In this paper, we provide a novel framework to assess the vulnerability/robustness of a network with respect to pair-wise nodes' connectivity. In particular, we consider attackers that aim, at the same time, at dealing the maximum possible damage to the network in terms of the residual connectivity after the attack and at keeping the cost of the at...

Understanding and controlling the behavior of dynamical distributed systems, especially biological ones, represents a challenging task. Such systems, in fact, are characterized by a complex web of interactions among their composing elements or subsystems. A typical pattern observed in these systems is the emergence of complex behaviors, in spite of...

It is well known that profiling attacker behavior is an effective way to obtain insights into network attacks and to identify the systems and components that must be protected. This paper presents a novel integer linear program- ming formulation that models the strategy of an attacker who targets a set of nodes with the goal of compromising or dest...

To address the problem the sensors were typically deployed in fixed positions, but the robots can be used to calibrate, deploy and maintain the surrounding wireless sensor network (WSN) in disaster relief applications, a novel framework was proposed to obtain a wide coverage of the unknown environment by the sensors, which can help the robot during...

Critical infrastructures are network-based systems which are prone to various types of threats (e.g., terroristic or cyber-attacks). Therefore, it is paramount to devise modelling frameworks to assess their ability to withstand external disruptions and to develop protection strategies aimed at improving their robustness and security. In this paper,...

The Analytic Hierarchy Process (AHP) is a de-facto standard technique in centralized decision making. Consider a situation where there is a need to rank a set of elements or alternatives, based on their value or utility, of which we just know pairwise relative information, i.e., the ratio of their values. AHP proved an effective tool to retrieve th...

In this paper we provide a distributed methodology to allow a network of agents, tasked to execute a distributed algorithm, to overcome Man-in-the-middle attacks that aim at steering the result of the algorithm towards inconsistent values or dangerous configurations. We want the agents to be able to restore the correct result of the algorithm in sp...

In this chapter we study the access time on random walks, i.e., the expected time for a random walk starting at a node \(v_i\) to reach a node \(v_j\), an index that can be easily calculated resorting to the powerful tools of positive systems. In particular, we argue that such an index can be the base for developing novel topological descriptors, n...

In this paper we present a novel distributed coverage control framework for a network of mobile agents, in charge of covering a finite set of points of interest (PoI), such as people in danger, geographically dispersed equipment or environmental landmarks. The proposed algorithm is inspired by the C-Means, an unsupervised learning algorithm origina...

In 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 dir...

In this paper we provide distributed algorithms to detect and remove cycles in a directed relational graph by exploiting the underlying undirected communication graph; the relational graph models a relation among the agents, e.g., a pairwise ordering, while the communication graph captures how information can be shared among them. Specifically, we...

The distributed calculation of node eccentricities, graph radius and graph diameter are fundamental steps to tune network protocols (e.g., setting an adequate time-to-live of packets), to select cluster heads, or to execute distributed algorithms, which typically depend on these parameters. Most existing methods deal with undirected topologies and...

The identification of Critical Nodes in technological, biological and social networks is a fundamental task in order to comprehend the behavior of such networks and to implement protection or intervention strategies aimed at reducing the network vulnerability. In this paper we focus on the perspective of an attacker that aims at disconnecting the n...

In 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 a...

In this paper we consider the localization of a sensor network where the nodes are heterogeneous, in that some of them are able to measure the distance from their neighbors, while some others are just able to detect their presence, and we provide a post-processing algorithm that can be used to improve an initial estimate for the location of the nod...