726 research outputs found

    Multi-hop Byzantine reliable broadcast with honest dealer made practical

    Get PDF
    We revisit Byzantine tolerant reliable broadcast with honest dealer algorithms in multi-hop networks. To tolerate Byzantine faulty nodes arbitrarily spread over the network, previous solutions require a factorial number of messages to be sent over the network if the messages are not authenticated (e.g., digital signatures are not available). We propose modifications that preserve the safety and liveness properties of the original unauthenticated protocols, while highly decreasing their observed message complexity when simulated on several classes of graph topologies, potentially opening to their employment

    Tractable reliable communication in compromised networks

    Get PDF
    Reliable communication is a fundamental primitive in distributed systems prone to Byzantine (i.e. arbitrary, and possibly malicious) failures to guarantee the integrity, delivery, and authorship of the messages exchanged between processes. Its practical adoption strongly depends on the system assumptions. Several solutions have been proposed so far in the literature implementing such a primitive, but some lack in scalability and/or demand topological network conditions computationally hard to be verified. This thesis aims to investigate and address some of the open problems and challenges implementing such a communication primitive. Specifically, we analyze how a reliable communication primitive can be implemented in 1) a static distributed system where a subset of processes is compromised, 2) a dynamic distributed system where part of the processes is Byzantine faulty, and 3) a static distributed system where every process can be compromised and recover. We define several more efficient protocols and we characterize alternative network conditions guaranteeing their correctness

    On a bone breccia near uliveto terme (Monte Pisano, Italy)

    Get PDF
    On a bone breccia near Uliveto Terme (Monte Pisano,Italy). The study of the macromammal remains of a bone breccia from the Uliveto quarry (Monte Pisano, Pisa) is here presented. The fossil material is scanty and very fragmented and consists mainly of Dama dama remains. The presence of Dama dama has been recognized also in another fossil site of the Monte Pisano (Grotta Cucigliana) referred to the late Aurelian

    Direct torque control for dual three-phase induction motor drives

    Get PDF
    A direct torque control (DTC) strategy for dual three-phase induction motor drives is discussed in this paper. The induction machine has two sets of stator three-phase windings spatially shifted by 30 electrical degrees. The DTC strategy is based on a predictive algorithm and is implemented in a synchronous reference frame aligned with the machine stator flux vector. The advantages of the discussed control strategy are constant inverter switching frequency, good transient and steady-state performance, and low distortion of machine currents with respect to direct self-control (DSC) and other DTC schemes with variable switching frequency. Experimental results are presented for a 10-kW DTC dual three-phase induction motor drive prototype

    Image fusion techniqes for remote sensing applications

    Get PDF
    Image fusion refers to the acquisition, processing and synergistic combination of information provided by various sensors or by the same sensor in many measuring contexts. The aim of this survey paper is to describe three typical applications of data fusion in remote sensing. The first study case considers the problem of the Synthetic Aperture Radar (SAR) Interferometry, where a pair of antennas are used to obtain an elevation map of the observed scene; the second one refers to the fusion of multisensor and multitemporal (Landsat Thematic Mapper and SAR) images of the same site acquired at different times, by using neural networks; the third one presents a processor to fuse multifrequency, multipolarization and mutiresolution SAR images, based on wavelet transform and multiscale Kalman filter. Each study case presents also results achieved by the proposed techniques applied to real data

    Multi-hop Byzantine Reliable Broadcast with Honest Dealer Made Practical

    Get PDF
    We revisit Byzantine tolerant reliable broadcast with honest dealer algorithms in multi-hop networks. To tolerate Byzantine faulty nodes arbitrarily spread over the network, previous solutions require a factorial number of messages to be sent over the network if the messages are not authenticated (e.g. digital signatures are not available). We propose modifications that preserve the safety and liveness properties of the original unauthenticated protocols, while highly decreasing their observed message complexity when simulated on several classes of graph topologies, potentially opening to their employment

    Reliable Broadcast despite Mobile Byzantine Faults

    Full text link
    We investigate the solvability of the Byzantine Reliable Broadcast and Byzantine Broadcast Channel problems in distributed systems affected by Mobile Byzantine Faults. We show that both problems are not solvable even in one of the most constrained system models for mobile Byzantine faults defined so far. By endowing processes with an additional local failure oracle, we provide a solution to the Byzantine Broadcast Channel problem

    Reuse of an ancient church: thermal aspect for integrated solutions

    Get PDF
    Abstract The definition of intervention strategies for the restoration and the functional actualization of historic and high artistic quality artifacts, postulates a systemic approach for the different variables that contribute to the definition of the project. This paper presents an emblematic case study of an historic building, the church of St. Francis in San Giovanni in Persiceto near Bologna, one of the most representative of the architectural construction of Bolognese Baroque, built by Alfonso Torreggiani. The expected new functions as exhibition hall and/or concert activities, requires a search for integrated strategies to ensure indoor comfort requirements (thermo-hygrometric, acoustics) and to define HVAC plant equipment for the reduction of energy consumption without affecting the historic values and artistic perception of the building. Therefore, the analysis of the church in the survey phase, besides the usual historical and architectural investigations, should investigate the potential issues and the critical aspects of structures, like the multilayered floor and refined decorations that lines the walls of the nave. Understanding the intimate rationality of the building (presence of any shafts, steps etc .) is a prerequisite for the inclusion of plant components without altering the visual perception and to optimize the acoustic and the climatization plant systems. Although the use of renewable energy are required today for all new plant systems, in this case it was decided to exclude invasive elements that could have altered the image of the entire monumental complex of which the church belongs. The proposed HVAC plant, after an analysis of dynamic thermal behaviour of the building, is an air-conditioning system coupled to radiant heating system to ensure, in a climate context with high humidity levels, the optimal temperature and humidity not only for comfort conditions but also for preservation of the building itself and of artistic works

    Contribution of natural milk culture to microbiota, safety and hygiene of raw milk cheese produced in alpine malga

    Get PDF
    Processing of alpine milk in malga farms is carried out under conditions that can favor contamination by coliforms, coagulase-positive staphylococci, or pathogens such as Listeria monocytogenes. With the aim to improve the hygienic characteristics and safety of cheese produced in four malga farms the use of lyophilized Natural Milk Culture prepared with selected strains was tested.. Two cheesemaking tests were carried out in the same day always starting from the same milk: in the first case following the malga recipe that uses either Natural Whey Culture or without the addition of a starter, in the second one using a Natural Milk Culture. Cheesemaking were carried out in four malga farms located in the west area of Trentino region within the same week. For hygienic and safety evaluation, aerobic colony count, coagulase-positive staphylococci, Escherichia coli, staphylococcal toxins, Listeria monocytogenes, and Salmonella spp, pH and aw were determined in raw milk from evening and morning milking, curd in vat, curd after extraction and two months-ripened cheese. Pathogens or toxins, high values of coagulase- positive staphylococci and E. coli were not found in cheese samples. However, in the curd coagulase-positive staphylococci reached values almost of 5 Log CFU/g in the two malga without starter cultures. The use of Natural Milk Culture reduced E. coli counts. In addition, DNA was extracted from cheese samples and from Natural Milk Culture and the composition of the microbial community determined by Next Generation Sequencing method. The determination of cheese microbial communities demonstrated that the use of Natural Milk Culture exerted different effects in the different malga, in any case preserving bacterial biodiversity

    Involvement of caspase-3 and GD3 ganglioside in ceramide-induced apoptosis in Farber disease

    Get PDF
    Farber's disease (FD) is a rare genetic disorder caused by ceramidase deficiency, which results in ceramide accumulation in lung, liver, colon, skeletal muscle, cartilage, and bone. Although this disease has been symptomatically characterized, little is known about its molecular pathogenetic process. Because recent studies reported that ceramide accumulation induces GD3 ganglioside formation and apoptosis, we investigated, in tissue obtained via colonoscopy from seriously involved patients, the possible involvement of ceramide in FD colonocyte destruction. Histochemical and TUNEL analyses of paraffin-embedded sections revealed that 45 ± 4.3% of FD colonocytes showed morphological signs of apoptosis compared with the 8 ± 2.3% of constitutive epithelial cell death. Importantly, immunohistochemical study for pro-apoptotic factors showed that GD3 accumulation colocalized with active caspase-3 and cleaved K18 in FD colon tissue. These findings provide evidence for a role of the apoptotic ceramide pathway in the pathogenesis of FD
    corecore