Ricerc@Sapienza

The world of machine-to-machine (M2M) communication is gradually moving from vertical single purpose solutions to multi-purpose and collaborative applications interacting across industry verticals, organizations and people - A world of Internet of Things (IoT). The dominant approach for delivering IoT applications relies on the development of cloud-based IoT platforms that collect all the data generated by the sensing elements and centrally process the information to create real business value.

A biosensor platform based on Bloch Surface Waves and operating in angular interrogation mode is applied to the detection of a clinical biomarker (HER2-neu/ERBB2) related to breast cancer initiation/progression. Preparing regions for specific recognition of different proteins as well as a reference on the biochip enables to correct the signal for nonspecific effects. Additionally, label-free analysis and surface wave enhanced fluorescence detection can be applied and compared directly on the platform. Cell lysates with high and low expression levels of ERBB2 are analyzed.

This paper shows a detailed analysis of the semiconductor-to-metal transition (SMT) in a vanadium dioxide (VO2) film deposited on silicon wafer. The vanadium dioxide phase transition is studied in the wide mid-infrared range 2-12 μm, by analyzing the transmittance and the reflectance measurements, and the calculated emissivity from the sample. The temperature behavior of the emissivity during the SMT put into evidence the phenomenon of the anomalous absorption in vanadium dioxide which has been explained by applying the Maxwell Garnett effective medium approximation theory.

We investigated a metamaterial composed by silicon carbide (SiC) subwavelength oriented wires, onto silicon substrate in the mid- to long- infrared range. A simple but versatile method was developed and implemented, combining homogenization techniques with the transfer matrix method for birefringent layered materials to model an effective medium layer where different inclusions content (filling factor) as well as different shape and orientation of inclusions (depolarization factors) are taken into account.

Here we investigated the SH generation at the wavelength of 400 nm (pump laser at 800 nm, 120 fs pulses) of a "metasurface" composed by an alternation of GaAs nano-grooves and Au nanowires capping portions of flat GaAs. The nano-grooves depth and the Au nanowires thickness gradually vary across the sample. The samples are obtained by ion bombardment at glancing angle on a 150 nm Au mask evaporated on a GaAs plane wafer. The irradiation process erodes anisotropically the surface, creating Au nanowires and, at high ion dose, grooves in the underlying GaAs substrate (pattern transfer).

We consider an anisotropic hyperbolic equation with memory term: ?t2u(x,t)=?i,j=1n?i(aij(x)?ju)+?0t?|?|?2b?(x,t,?)?x?u(x,?)d?+R(x,t)f(x) for $x \in \Omega$ and $t\in (0, T)$ , which is a simplified model equation for viscoelasticity. The main result is a both-sided Lipschitz stability estimate for an inverse source problem of determining a spatial varying factor $f(x)$ of the force term $R(x, t)\,f(x)$ .

In this paper, we introduce a discrete time-finite state model for pedestrian flow on a graph in the spirit of the Hughes dynamic continuum model. The pedestrians, represented by a density function, move on the graph choosing a route to minimize the instantaneous travel cost to the destination. The density is governed by a conservation law whereas the minimization principle is described by a graph eikonal equation.

A directed multigraph is said vulnerable if it can generate Braess paradox in traffic networks. In this paper, we give a graph–theoretic characterisation of vulnerable directed multigraphs. Analogous results appeared in the literature only for undirected multigraphs and for a specific family of directed multigraphs. The proof of our characterisation provides the first polynomial time algorithm that checks if a general directed multigraph is vulnerable in O(| V| · | E|2).

Software Defined Networking (SDN) is a recent network architecture based on the separation of forwarding functions from network logic, and provides high flexibility in the management of the network. In this paper, we show how an attacker can exploit SDN programmability to obtain detailed knowledge about the network behaviour. In particular, we introduce a novel attack, named Know Your Enemy (KYE), which allows an attacker to gather vital information about the configuration of the network.

Containers are increasingly adopted, because they simplify the deployment and management of applications. Moreover, the ever increasing presence of IoT devices and Fog computing resources calls for the development of new approaches for decentralizing the application execution, so to improve the application performance. Although several solutions for orchestrating containers exist, the most of them does not efficiently exploit the characteristics of the emerging computing environment.