131 research outputs found

    Deadline-Aware Scheduling Perspectives in Industrial Wireless Networks: A Comparison between IEEE 802.15.4 and Bluetooth

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    In industrial contexts, most of process control applications use wired communication networks. The reliability of wired networks is indisputable and extensively demonstrated by several studies in the literature. However, it is important to consider several disadvantages provided by the use of wired technologies, like high deployment and maintenance costs and low network scalability. Although it is difficult to fully replace wired networks, wireless communication protocols have features which could undeniably affect in positive way the production mechanisms in factories. The wireless networks (WNs) are effectively used to detect and exchange information. The main communication protocols, currently available for WNs, however, do not support real-time periodic traffic flows which, as known, mainly characterize industrial networks. In this paper, we will analyze a real-time scheduling algorithm for both periodic and aperiodic traffic management, applied to networks based on IEEE 802.15.4 and Bluetooth, respectively. The main purpose of this research is to reduce, as much as possible, the packet loss on the channel, increasing at the same time the reliability of the wireless technology. Furthermore, the comparison between IEEE 802.15.4 and Bluetooth will allow to identify the more suitable communication protocol for industrial process control systems

    A METHODOLOGY FOR DESIGN SPACE EXPLORATION OF REAL-TIME LOCATION SYSTEMS

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    Scope of Research. This paper deals with the problem of design space exploration for a particular class of networked embedded systems called Real-Time Location Systems (RTLS). Methods. The paper contains a clear and detailed plan of anongoing research and could be considered as a review, a vision and a statement of objectives. Analytical and formal methods, simulation and automated verification will be involved in the research. Main Results. Analysis of the state of the art (current design flow, existing simulation tools and verification techniques) has revealed several limitations for performing efficientdesign space exploration of RTLS, especially for safety-critical applications. The review part of the paper also contains a clear problem statement. The main outcome of this research is the proposed vision of a novel methodology for determining the best-suited technology and its configuration from the space of potential solutions. In particular, it is planned to extend an existing simulation framework and apply automated verification techniques. The latter will be used for checking simulation results and also for exploring different system configuration alternatives, that is, to optimize the design, which is a novel approach. A case study for validating the methodology is also proposed. Practical Significance. The proposed methodology will highly increase the breadth of design space exploration of RTLS as well as the confidence on taken design decisions. It will also contribute to optimizing the design

    a dynamic traffic light management system based on wireless sensor networks for the reduction of the red light running phenomenon

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    Abstract The real-time knowledge of information concerning traffic light junctions represents a valid solution to congestion problems with the main aim to reduce, as much as possible, accidents. The Red Light Running (RLR) is a behavioural phenomenon that occurs when the driver must to choose to cross (or not) the road when the traffic light changes from green to yellow. Most of the time the drivers cross even during transitions from yellow to red and, as a consequence, the possibility of accidents increases. This often occurs because the drivers wait too much in the traffic light queue as a consequence of the fact that the traffic light is not well balanced. In this paper we propose a technique that, based on information gathered through a wireless sensor network, dynamically processes green times in a traffic light of an isolated intersection. The main aim is to optimise the waiting time in the queue and, as a consequence, reduce the RLR phenomenon occurrence

    A Dynamic Traffic Light Management System Based on Wireless Sensor Networks for the Reduction of the Red-Light Running Phenomenon

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    The real-time knowledge of information concerning traffic light junctions represents a valid solution to congestion problems with the main aim to reduce, as much as possible, accidents. The Red Light Running (RLR) is a behavioural phenomenon that occurs when the driver must to choose to cross (or not) the road when the traffic light changes from green to yellow. Most of the time the drivers cross even during transitions from yellow to red and, as a consequence, the possibility of accidents increases. This often occurs because the drivers wait too much in the traffic light queue as a consequence of the fact that the traffic light is not well balanced. In this paper we propose a technique that, based on information gathered through a wireless sensor network, dynamically processes green times in a traffic light of an isolated intersection. The main aim is to optimise the waiting time in the queue and, as a consequence, reduce the RLR phenomenon occurrence

    Handling timing constraints violations in soft real-time applications as exceptions

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    In this paper, an exception-based programming paradigm is envisioned to deal with timing constraints violations occurring in soft real-time and multimedia applications written in the C language. In order to prove viability of the approach, a mechanism allowing to use such paradigm has been designed and implemented as an open-source library of C macros making use of the standard POSIX API (a few Linux-specific optimizations are also briefly discussed). The proposed approach has been validated by modifying mplayer, one of the most widely used multimedia player for Linux, so as to use the introduced library. An extensive experimental evaluation has been made, both when running the player alone and when mixing it with a workload of other synthetic real-time applications. In the latter case, different scheduling policies have been used, including both standard priority-based ones as available on the mainline Linux, and an experimental deadline-based one available as a separate patch. The shown results demonstrate how the exception-based paradigm is effective in improving the audio/video delay exhibited by the player achieving a superior performance and a dramatically better quality of experience as compared to the original heuristic frame-dropping mechanism of the player

    Le Fosse Ardeatine: un'architettura per non dimenticare

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    Vicende politiche e costruttive del monumento ai martiri delle Fosse Ardeatin
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