New results on semileptonic b decays from LHCb

We report new measurements, based on the Run I dataset collected by the LHCb experiment, of the B0 mixing frequency Dm_d and the CKM matrix element |V_ub| using semileptonic b decays. The former is the most precise measurement ever performed; the latter represents the first determination of |V_ub| using a baryonic decay, and adds an important constraint on a possible explanation for the discrepancy between exclusive and inclusive determinations of this observable.Comment: Presentation at the DPF 2015 Meeting of the American Physical Society Division of Particles and Fields, Ann Arbor, Michigan, August 4-8, 201

The Algebra of Directed Acyclic Graphs

We give an algebraic presentation of directed acyclic graph structure, introducing a symmetric monoidal equational theory whose free PROP we characterise as that of finite abstract dags with input/output interfaces. Our development provides an initial-algebra semantics for dag structure

Observer design for piecewise smooth and switched systems via contraction theory

The aim of this paper is to present the application of an approach to study contraction theory recently developed for piecewise smooth and switched systems. The approach that can be used to analyze incremental stability properties of so-called Filippov systems (or variable structure systems) is based on the use of regularization, a procedure to make the vector field of interest differentiable before analyzing its properties. We show that by using this extension of contraction theory to nondifferentiable vector fields, it is possible to design observers for a large class of piecewise smooth systems using not only Euclidean norms, as also done in previous literature, but also non-Euclidean norms. This allows greater flexibility in the design and encompasses the case of both piecewise-linear and piecewise-smooth (nonlinear) systems. The theoretical methodology is illustrated via a set of representative examples.Comment: Preprint accepted to IFAC World Congress 201

Hiding mobile traffic fingerprints with GLOVE

Proceeding of: 11th ACM Conference on Emerging Networking Experiments and Technologies ACM (CoNEXT 2015), Heidelberg, Germany, 1-4 December 2015Preservation of user privacy is paramount in the publication of datasets that contain fine-grained information about individuals. The problem is especially critical in the case of mobile traffic datasets collected by cellular operators, as they feature high subscriber trajectory uniqueness and they are resistant to anonymization through spatiotemporal generalization. In this work, we first unveil the reasons behind such undesirable features of mobile traffic datasets, by leveraging an original measure of the anonymizability of users' mobile fingerprints. Building on such findings, we propose GLOVE, an algorithm that grants k-anonymity of trajectories through specialized generalization. We evaluate our methodology on two nationwide mobile traffic datasets, and show that it achieves k-anonymity while preserving a substantial level of accuracy in the data.This work was supported by the French National Research Agency under grant ANR-13-INFR-0005 ABCD and by the EU FP7 ERA-NET program under grant CHIST-ERA-2012 MACACO

On the level of detail of synthetic highway traffic necessary to vehicular networking studies

Proceeding of: 2015 IEEE Vehicular Networking Conference (VNC), Kyoto, Japan, 16-18 December, 2015The proper modeling of road traffic is paramount to the dependability of studies on vehicular networking solutions intended for highway environments. Yet, it is not clear which is the actual level of detail in the mobility representation that is sufficient and necessary to such studies. This uncertainty results into a variety of approaches being adopted in the literature, and ultimately undermines the reliability and reproducibility of research outcomes. We explore the space of possible mobility models and performance metrics, and pinpoint the level of detail needed for different types of vehicular networking studies.The research leading to these results was carried out while Marco Gramaglia was at CNR-IEIIT, and has received funding from the People Programme (Marie Curie Actions) of the European Unions Seventh Framework Programme (FP7/2007-2013) under REA grant agreement n.630211 ReFleX.Publicad

Studio di processi di gassificazione di fanghi da depurazione civile

Attualmente lo smaltimento dei fanghi da depurazione civile è reso sempre più problematico dalle normative vigenti che sono sempre più restrittive e limitano il ricorso ai metodi tradizionali (discarica, compostaggio, riutilizzo in agricoltura). Nell'ambito di uno studio finalizzato all'individuazione di sistemi di trattamento alternativi si inserisce il presente lavoro di tesi, il cui obiettivo è valutare l'applicazione del processo di gassificazione ai fanghi provenienti dalla depurazione di reflui civili. La sperimentazione è stata realizzata impiegando un impianto pilota di gassificazione a letto fisso in modalità up-draft. Lo studio si è articolato nelle seguenti attività: messa a punto, gestione, monitoraggio delle prestazioni dell’impianto pilota, campionamento e analisi del gas prodotto (syngas). Sulla base dei risultati sperimentali ottenuti sono stati impostati bilanci materiali e termici al fine di quantificare i flussi di materia e di energia connessi al processo per stimare le possibili configurazioni di recupero energetico