299 research outputs found

    Software dependability techniques validated via fault injection experiments

    Get PDF
    The present paper proposes a C/C++ source-to-source compiler able to increase the dependability properties of a given application. The adopted strategy is based on two main techniques: variable duplication/triplication and control flow checking. The validation of these techniques is based on the emulation of fault appearance by software fault injection. The chosen test case is a client-server application in charge of calculating and drawing a Mandelbrot fracta

    Validation of a software dependability tool via fault injection experiments

    Get PDF
    Presents the validation of the strategies employed in the RECCO tool to analyze a C/C++ software; the RECCO compiler scans C/C++ source code to extract information about the significance of the variables that populate the program and the code structure itself. Experimental results gathered on an Open Source Router are used to compare and correlate two sets of critical variables, one obtained by fault injection experiments, and the other applying the RECCO tool, respectively. Then the two sets are analyzed, compared, and correlated to prove the effectiveness of RECCO's methodology

    Data criticality estimation in software applications

    Get PDF
    In safety-critical applications it is often possible to exploit software techniques to increase system's fault- tolerance. Common approaches are based on data redundancy to prevent data corruption during the software execution. Duplicating most critical variables only can significantly reduce the memory and performance overheads, while still guaranteeing very good results in terms of fault-tolerance improvement. This paper presents a new methodology to compute the criticality of variables in target software applications. Instead of resorting to time consuming fault injection experiments, the proposed solution is based on the run- time analysis of the variables' behavior logged during the execution of the target application under different workloads

    Control-flow checking via regular expressions

    Get PDF
    The present paper explains a new approach to program control flow checking. The check has been inserted at source-code level using a signature methodology based on regular expressions. The signature checking is performed without a dedicated watchdog processor but resorting to inter-process communication (IPC) facilities offered by most of the modern operating systems. The proposed approach allows very low memory overhead and trade-off between fault latency and program execution time overhead

    PROMON: a profile monitor of software applications

    Get PDF
    Software techniques can be efficiently used to increase the dependability of safety-critical applications. Many approaches are based on information redundancy to prevent data and code corruption during the software execution. This paper presents PROMON, a C++ library that exploits a new methodology based on the concept of "Programming by Contract" to detect system malfunctions. Resorting to assertions, pre- and post-conditions, and marginal programmer interventions, PROMON-based applications can reach high level of dependabilit

    FAUST: fault-injection script-based tool

    Get PDF
    The tool described in this paper aims at evaluating the effectiveness of software-implemented fault-tolerant techniques used in safety-critical systems. The target application is stressed with the injection of transient or permanent faults. The user can therefore observe the real behaviour of the application in presence of a fault, and, if necessary, take the appropriate countermeasures. The accent is put on the extreme easiness of the use and the portability on all UNIX platforms

    An Energy Saving Road Sweeper Using Deep Vision for Garbage Detection

    Get PDF
    Road sweepers are ubiquitous machines that help preserve our cities cleanliness and health by collecting road garbage and sweeping out dirt from our streets and sidewalks. They are often very mechanical instruments, needing to operate in harsh conditions dealing with all sorts of abandoned trash and natural garbage. They are usually composed of rotating brushes, collector belts and bins, and sometimes water or air streams. All of these mechanical tools are usually high in power demand and strongly subject to wear and tear. Moreover, due to the simple working logic often implied by these cleaning machines, these tools work in an “always on”/“max power” state, and any further regulation is left to the pilot. Therefore, adding artificial intelligence able to correctly operate these tools in a semi-automatic way would be greatly beneficial. In this paper, we propose an automatic road garbage detection system, able to locate with great precision most types of road waste, and to correctly instruct a road sweeper in order to handle them. With this simple addition to an existing sweeper, we will be able to save more than 80% electrical power currently absorbed by the cleaning systems and reduce by the same amount brush weariness (prolonging their lifetime). This is done by choosing when to use the brushes and when not to, with how much strength, and where. The only hardware components needed by the system will be a camera and a PC board able to read the camera output (and communicate via CanBus). The software of the system will be mainly composed of a deep neural network for semantic segmentation of images, and a real-time software program to control the sweeper actuators with the appropriate timings. To prove the claimed results, we run extensive tests onboard of such a truck, as well as benchmark tests for accuracy, sensitivity, specificity and inference speed of the system

    Recycling of yttria-stabilized zirconia waste powders in glazes suitable for ceramic tiles

    Get PDF
    The aim of this work is to demonstrate the feasibility of valorizing and recycling Yttria-stabilized Zirconia thermal spray waste into high value products for industrial and residential use. Based on the powders chemistry and morphology, this work aims to realize products, like frits suitable for white glazes and ceramic tiles. The focus is on one class of powder: high-temperature and abrasion-resistant ceramics, like Yttria-stabilized zirconia. This study has revealed that the substitution of pure zirconia with waste Yttria-stabilized zirconia is possible in high percentages, up to 100% to prepare frits suitable for white glaze

    CFD Simulation of Binary Fluidized Mixtures: Effects of Restitution Coefficient and Spatial Discretization Methods

    Get PDF
    The work focuses on the CFD simulation of fluidized bidisperse solid particles with same density and different size. We successfully predicted the minimum superficial gas velocity required to steadily fluidize the particles by employing a second-order upwind spatial discretization method and a non-ideal value of the restitution coefficient

    X-Ray Absorption By WHIM in the Sculptor Wall

    Full text link
    We present XMM RGS and Chandra LETG observations of the blazar, H 2356-309, located behind the Sculptor Wall, a large-scale galaxy structure expected to harbor high-density Warm-Hot Intergalactic Medium (WHIM). Our simultaneous analysis of the RGS and LETG spectra yields a 3-sigma detection of the crucial redshifted O vii K-alpha line with a column density (>~ 10^{16} cm^{-2}) consistent with similar large-scale structures produced in cosmological simulations. This represents the first detection of non-local WHIM from X-ray absorption studies where XMM and Chandra data are analyzed simultaneously and the absorber redshift is already known, thus providing robust evidence for the expected repository of the "missing baryons".Comment: Accepted for Publication in The Astrophysical Journal, 7 pages, 2 figure