Gossip Algorithms for Distributed Signal Processing

Gossip algorithms are attractive for in-network processing in sensor networks because they do not require any specialized routing, there is no bottleneck or single point of failure, and they are robust to unreliable wireless network conditions. Recently, there has been a surge of activity in the computer science, control, signal processing, and information theory communities, developing faster and more robust gossip algorithms and deriving theoretical performance guarantees. This article presents an overview of recent work in the area. We describe convergence rate results, which are related to the number of transmitted messages and thus the amount of energy consumed in the network for gossiping. We discuss issues related to gossiping over wireless links, including the effects of quantization and noise, and we illustrate the use of gossip algorithms for canonical signal processing tasks including distributed estimation, source localization, and compression.Comment: Submitted to Proceedings of the IEEE, 29 page

Salt-regulating hormones in young normotensive obese subjects. Effects of saline load.

To investigate whether the response of salt-regulating hormones to volume expansion is impaired in obese subjects, we assessed the effects of saline load (0.25 mL/kg.min.120 min) in 9 young, healthy, normotensive obese subjects (body mass index, > 30 kg/m2) and in 10 lean control subjects (body mass index, < 25 kg/m2) matched for age, gender, height, and mean blood pressure. Hematocrit, plasma renin activity (PRA), plasma aldosterone (PA), atrial natriuretic factor (ANF), and urinary sodium excretion (UNaV) were evaluated. Saline load increased ANF levels significantly (P < .001) in lean subjects at both 60 and 120 minutes, whereas they decreased in obese subjects. Such decreases became significant (P < .01) at 120 minutes. Suppression of PRA and PA by saline load were more marked in lean than obese subjects. Hematocrit decreased in both groups, and UNaV increased more in lean than obese subjects during saline load. Comparisons of percent changes in ANF, PRA, and PA after saline load showed that the responses of lean and obese subjects were significantly different (P < .001 for ANF at both 60 and 120 minutes; P < .05 for PRA and PA at both 60 and 120 minutes). In conclusion, the lack of ANF response and the reduced suppression of PRA and PA to saline load indicate a dysfunction of these systems in obese subjects. This alteration may be involved in the higher susceptibility of obese subjects to developing hypertension

Obesità e rischio cardiovascolare.

L’obesità rappresenta attualmente la più diffusa patologia da malnutrizione delle Società occidentali industrializzate e si associa spesso a svariate complicanze invalidanti sia mediche che chirurgiche. Essa è, inoltre, una condizione ad elevata prevalenza ed in continuo e costante incremento, al punto da essere etichettata come una “Epidemia globale”. Nella presente review sono stati analizzati i risultati degli studi più recenti che hanno individuato nella patologia del tessuto adiposo uno dei meccanismi più importanti nello sviluppo dell’aterosclerosi e delle manifestazioni cliniche ad essa connesse. Particolare riguardo è stato dato, oltre che alle evidenze epidemiologiche riguardanti i rapporti tra obesità e morbilità e mortalità cardiovascolare, anche alle relazioni tra grado e tipo di obesità, diabete, dislipidemia, ipertensione, e alle ripercussioni di queste condizioni sulla geometria e sulla funzione ventricolare sinistra per una corretta valutazione del rischio cardiovascolare del soggetto obeso. Un ultimo paragrafo ha riguardato l’analisi del ruolo sempre più rilevante della correzione dell’eccesso ponderale, tramite adeguati interventi dietetico-comportamentali e/o farmacologici, nelle strategie preventive delle malattie e/o degli eventi cardiovascolari

Comparison between Voltage Oriented Control and Synchronous Power Control for Grid-Connected Inverter Applications

With the rising of renewable power generation, there are new challenges to be addressed in order to maintain the electrical system operation stability. So, in literature, new grid-connected inverter control techniques have been studied. This paper focuses on a comparison between a grid-following control technique, called Voltage Oriented Control and a grid-forming control technique, called Synchronous Power Control, to underline the advantages offered by the latter. Through a simulation analysis in Matlab/Simulink environment, the benefits and drawbacks of these control approaches have been analyzed and discussed

Non \ue8 pi\uf9 quella di una volta. La mafia e le attivit\ue0 estorsive in Sicilia

Il volume presenta i risultati di una ricerca volta alla descrizione dei fenomeni estorsivi e della loro intensit\ue0 in Sicilia, raccontando, sulla base di appositi parametri oggettivi e di valutazioni soggettive degli esponenti del mondo delle associazioni e delle forze dell\u2019ordine, le aree pi\uf9 esposte, quelle meno esposte, quelle dove i fenomeni hanno una rilevanza residuale, in una fase in cui i sodalizi mafiosi sono sempre pi\uf9 pressati dall\u2019azione di contrasto. Per raggiungere questo obiettivo ci si \ue8 avvalsi di strumenti qualitativi e dati quantitativi, approfondendo l\u2019analisi delle trasformazioni delle condotte estorsive durante la crisi, concentrandosi in modo specifico su casi emersi nell\u2019ambito di recenti inchieste giudiziarie. Il libro ricostruisce anche la prospettiva e le difficolt\ue0 di alcuni imprenditori siciliani che, dopo aver pagato il pizzo, hanno scelto di denunciare i propri estorsori e di collaborare con le istituzioni

A Novel Multi-Objective Finite Control Set Model Predictive Control for IPMSM drive fed by a Five-Level Cascaded H-Bridge Inverter

In this work, a novel multi-objective voltage-vector-based finite control set model predictive control for a permanent magnet synchronous machine drive fed by a three-phase five-level cascaded H-bridge multilevel inverter is proposed. This algorithm aims to overcome the main issues relative to model predictive control implementation detected in the scientific literature for electric drives fed by cascaded H-bridge multilevel inverters. In detail, the goals are the minimization of computational cost by reducing the number of required predictions, the minimization of the switching devices state transitions, i.e. the switching losses minimization, and the common mode voltage reduction. These goals are fulfilled through an offline optimization process, thus, no additional terms and weighting factors to be tuned are required for the cost function. Experimental validations are presented to prove the effectiveness of the proposed approach. In detail, an accurate electric drive performance comparison, both in steady state and dynamic working conditions, is carried out when the proposed voltage-vector-based model predictive control and the cell-by-cell-based model predictive control are adopted. As comparison tools, current and voltage total harmonic distortion, apparent switching frequency, common mode voltage amplitude, and torque ripple are adopted

Degradation of the surfaces exposed to the space environment

The presence of several atomic species in the LEO (Low Earth Orbits) could be considered one of the reasons for the degradation of the surfaces exposed to the Space Environment. At an average height of 400 Km (the altitude of International Space Station), the concentration of the main atomic species during the high sun activity are: 1.5 x 10(9) cm(-3) for atomic oxygen (AO), 1.6 x 10(8) cm(-3) for molecular nitrogen (N-2) and 1.4 x 10(8) m(-3) for atomic nitrogen (N). The energy with which the atoms collide with the surface of orbiting vehicle depends on the relative speed of the vehicle itself. For instance, the atoms colliding the International Space Station (ISS) (orbit average height: 400 Km; relative speed: 7.5 Km/s) have an energy of 8 eV for N-2, 5 eV for OA and 4 eV for N. The atomic oxygen is the most abundant species presents in LEO and it is considered the main responsible of the thermal, optical and mechanical alteration of the surfaces exposed to the Space Environment. Different hypothesis are reported in literature in order to explain the physical/chemical mechanisms that govern the material degradation in the Space, but no conclusion has been reached. In the energy range of few of eV, the main mechanism with which colliding atoms transfer its energy to the atoms of the surface is by phonons. In this paper the effect of an oxygen ion beam produced in the space environment simulator on materials for Space applications is studied in the frame of the thermal spike theory. Comparison between the measured erosion and the calculated one will be reported. The erosion mechanism will be modelled in order to understand the main thermodynamic parameters that govern the interaction between the atomic oxygen and the surface of the tested materials. (c) 2006 Elsevier Ltd. All rights reserved