Lyapunov optimization is a powerful control technique that allows the stabilisation of real or virtual queues while optimizing a performance objective. The method has become popular due to the fact that it applies a greedy optimization that does not rely on any statistical knowledge of the underlying process. Moreover, the technique includes a parameter V to control the stability vs utility trade-off, offering a theoretical bound on the performance. However, in its basic form, the optimization ensures that queues are only asymptotically stable, and there is no guarantee that queues will stay below a given threshold at all times. This can affect the applicability of this technique to many applications with queues with limited capacity or, equivalently, systems with hard delay constraints. In this paper we analyse the conditions under which it is possible to set a queue maximum capacity constraint, and we provide a technique to set an extra bound on the parameter V to enforce such constraint.

Many vehicular ad-hoc network protocols have been validated using complex urban mobility simulators or by means of the few publicly available real mobility traces. This work presents an extensive measurement campaign of the positions of a fleet of 370 taxi cabs moving around the city of Rome, Italy. Due to its street network and its traffic conditions, Rome presents a characteristic mobility pattern representative of an ancient city with heavy road congestion, and therefor provides a valuable test case to experiment VANET protocols. We exploit these traces to run a set of experiments to assess the performance of a simple epidemic protocol that we compare with the basic random waypoint model in order to quantify how far the performance metrics are from this baseline. The results show the possible outcomes of implementing data dissemination through an opportunistic network that\ud uses taxi cabs as an information vector

The growing integration of software within medical devices introduces the potential for cybersecurity threats. How significant is this risk, and to what extent are citizens currently exposed? In this study, we adopt a new data-gathering methodology using datasets provided in Open Contracting Data Standard (OCDS). This allowed us to perform an extensive analysis across over 36 countries within a 12-year range, searching 92 million public administration purchase records for potentially vulnerable medical devices. The findings reveal a concerning landscape wherein numerous medical devices purchased by national health services possessed or still possess 661 distinct vulnerabilities—more than half of which are deemed critical or high-severity. These vulnerabilities enable relatively simple attacks to impact data confidentiality, integrity, and accessibility severely. Even if patches were applied immediately upon discovery, these vulnerabilities would still result in roughly 3.2 years of system exposure from the time a device is purchased until a software vulnerability is announced, with all classes of devices affected, including high-risk IIB and III devices which accounts for 74% of instances. While a full analysis requires interactivity, this noninvasive methodology enables a large-scale study, emphasizing the need to move faster from the safety to the security of medical devices.

The design of wireless sensor nodes for animal tracking is a multidisciplinary activity that presents several research challenges both from a technical and a biological point of view. A monitoring device has to be designed accounting for all system requirements including the specific characteristics of animals and environment. In this work we present some aspects of the design of a wireless sensor node to track and monitor the pink iguana of the Galápagos: a recently discovered species living in remote locations at the Galápagos Islands. The few individuals of this species live in a relatively small area that lacks of any available communication infrastructure. We present and discuss the energy harvesting architecture and the related energy management logic. We also discuss the impact of packaging on the sensor performance and the consequences of the limited available energy on the GPS tracking.