Maximizing Profit in Green Cellular Networks through Collaborative Games

In this paper, we deal with the problem of maximizing the profit of Network Operators (NOs) of green cellular networks in situations where Quality-of-Service (QoS) guarantees must be ensured to users, and Base Stations (BSs) can be shared among different operators. We show that if NOs cooperate among them, by mutually sharing their users and BSs, then each one of them can improve its net profit. By using a game-theoretic framework, we study the problem of forming stable coalitions among NOs. Furthermore, we propose a mathematical optimization model to allocate users to a set of BSs, in order to reduce costs and, at the same time, to meet user QoS for NOs inside the same coalition. Based on this, we propose an algorithm, based on cooperative game theory, that enables each operator to decide with whom to cooperate in order to maximize its profit. This algorithms adopts a distributed approach in which each NO autonomously makes its own decisions, and where the best solution arises without the need to synchronize them or to resort to a trusted third party. The effectiveness of the proposed algorithm is demonstrated through a thorough experimental evaluation considering real-world traffic traces, and a set of realistic scenarios. The results we obtain indicate that our algorithm allows a population of NOs to significantly improve their profits thanks to the combination of energy reduction and satisfaction of QoS requirements.Comment: Added publisher info and citation notic

Forensic Analysis of the ChatSecure Instant Messaging Application on Android Smartphones

We present the forensic analysis of the artifacts generated on Android smartphones by ChatSecure, a secure Instant Messaging application that provides strong encryption for transmitted and locally-stored data to ensure the privacy of its users. We show that ChatSecure stores local copies of both exchanged messages and files into two distinct, AES-256 encrypted databases, and we devise a technique able to decrypt them when the secret passphrase, chosen by the user as the initial step of the encryption process, is known. Furthermore, we show how this passphrase can be identified and extracted from the volatile memory of the device, where it persists for the entire execution of ChatSecure after having been entered by the user, thus allowing one to carry out decryption even if the passphrase is not revealed by the user. Finally, we discuss how to analyze and correlate the data stored in the databases used by ChatSecure to identify the IM accounts used by the user and his/her buddies to communicate, as well as to reconstruct the chronology and contents of the messages and files that have been exchanged among them. For our study we devise and use an experimental methodology, based on the use of emulated devices, that provides a very high degree of reproducibility of the results, and we validate the results it yields against those obtained from real smartphones

Engineering of Substrate Surface for the synthesis of Ultra-Thin Composite Pd and Pd-Cu Membranes for H2 Separation

This work describes a novel technique to prepare ultra-thin composite Pd-porous metal membranes for H2 separation. This novel technique consists of the gradual smoothing of the Porous Metal (PM) support\u27s surface with several layers of pre-activated alumina particles of different sizes. The deposition of coarse, fine and ultra-fine alumina particles resulted in the narrowing of the PM\u27 surface pore size distribution. The excellent surface smoothness achieved after the grading of the PM \u27s surface support allowed for the preparation of gas tight Pd layers as thin as 5.6?m. The Pd layers were extremely uniform due to the presence of the grade layer and strongly attached to the support. Composite Pd membranes prepared on graded supports showed H2 permeance as high as 50 m3/(m2 h bar0.5) at 500ºC and ideal selectivities (H2/He) as high as 27000. Moreover, the H2 permeance and ideal selectivity were stable over 1100 hours at 500ºC in H2 atmosphere. Composite Pd-Cu membranes showed H2 permeance as high as 30 m3/(m2 h bar0.5) at 450ºC and ideal selectivities (H2/He) as high as 900. The H2 permeance and ideal selectivity of Pd-Cu membranes were stable over 500 hours at 450ºC in H2 atmosphere. The outstanding long-term H2 permeance and ideal selectivity stability of all composite Pd and Pd-Cu membranes represented a breakthrough in composite Pd membrane synthesis. The thermal stresses arising from the mismatch in the coefficient of thermal expansion between the Pd film and the support were determined by means of x-ray diffraction. The results indicated that the release of stresses began to occur at temperatures close to 400ºC. Also, the release of stresses took place with a visible sintering of Pd clusters within the thin Pd film. The stresses due to the absorption of H2 were also studied and modeled. It was estimated that the maximum compressive stress under which these composite Pd membranes were characterized was equal to 260 MPa

A Game-Theoretic Approach to Coalition Formation in Fog Provider Federations

In this paper we deal with the problem of making a set of Fog Infrastructure Providers (FIPs) increase their profits when allocating their resources to process the data generated by IoT applications that need to meet specific QoS targets in face of time-varying workloads. We show that if FIPs cooperate among them, by mutually sharing their workloads and resources, then each one of them can improve its net profit. By using a game-theoretic framework, we study the problem of forming stable coalitions among FIPs. Furthermore, we propose a mathematical optimization model for profit maximization to allocate IoT applications to a set of FIPs, in order to reduce costs and, at the same time, to meet the corresponding QoS targets. Based on this, we propose an algorithm, based on cooperative game theory, that enables each FIP to decide with whom to cooperate in order to increase its profits. The effectiveness of the proposed algorithm is demonstrated through an experimental evaluation considering various workload intensities. The results we obtain from these experiments show the ability of our algorithm to form coalitions of FIPs that are stable and profitable in all the scenarios we consider

Il conflitto israelo-palestinese 1993-2010. Vincitori e vinti senza pace.

Questo volume nasce dall’esigenza di offrire agli studenti universitari e al più vasto pubblico italiano un’analisi approfondita dello stato attuale del conflitto israelo-palestinese, mantenendo tuttavia uno sguardo alle sue dinamiche storiche. Dopo un capitolo introduttivo sulle politiche di occupazione israeliane e sul quadro politico e diplomatico che ha accompagnato il conflitto dalla fine della guerra fredda, il volume è diviso in tre parti: (1) la prima analizza il ruolo degli attori internazionali (USA e Unione Europea) nel conflitto; (2) la seconda è dedicata all’evoluzione della politica interna israeliana; (3) e, infine, la terza, esamina l’evoluzione della politica interna palestinese fino ad arrivare allo scontro attuale fra Hamas e Fatah. Gli autori dei capitoli sono esperti di provenienza accademica che lavorano da anni sul conflitto nei loro rispettivi ambiti scientifici e che, insieme, cercano di dare risposte chiare a domande apparentemente semplici quali: “Perché il processo di pace di Oslo è fallito? Perché, nonostante il fallimento di Oslo e le guerre ricorrenti, si continua a parlare di un ‘processo di pace’ israelo-palestinese, scandito da inconcludenti rituali diplomatici? Perché Israele continua a costruire insediamenti nei Territori occupati palestinesi? Perché la classe politica palestinese si è spaccata al punto da determinare una situazione di quasi guerra civile?”. Contributi di Marco Allegra, Benoit Challand, Paolo di Motoli, Maria Grazia Enardu, Laura Guazzone, Daniela Pioppi, Nathalie Tocci