Nowadays, industrial communicationsystems are experiencing the introduction of wireless technologies at all levels of automated factories. the benefits that derive from such a choice are manifold, including reduced d...
ISBN:
(纸本)9781424427284
Nowadays, industrial communicationsystems are experiencing the introduction of wireless technologies at all levels of automated factories. the benefits that derive from such a choice are manifold, including reduced deployment costs, enhanced flexibility and support for mobility. Unfortunately, because of a number of reasons, wireless systems can not be thought of as a complete replacement of wired networks at the field level. In this paper, the performance that can be achieved by QoS-enabled WLANs to support communication in industrial environments is analyzed. In particular, a detailed analysis of latencies in infrastructure networks is presented, obtained through numerical simulations, that takes into account both media access and queuing delays. Moreover, the impact of the internal architecture of the access point on performance is evaluated as well.
Information and communication technologies (ICT) play an innovation driver role. Traditional information system technologies and Web 2.0 joint exploitation is investigated as a research topic in service systems. Two s...
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Information and communication technologies (ICT) play an innovation driver role. Traditional information system technologies and Web 2.0 joint exploitation is investigated as a research topic in service systems. Two service systems categories are investigated: traditional information systems (centralized, federated, etc.) and systems exploiting Web 2.0 technologies, based on social networks. the analysis mainly focuses on the following variables: knowledge, technology, and relationships among the service actors. the analysis is contextualized through the labour market place domain, focusing on job search services supported by ICT. Convergences and divergences can be found on the several service implementations that have been analyzed (based respectively on traditional information systems and on Web 2.0 technologies). A possible integration between social network and traditional service systems is envisioned, resulting in an enhanced way of designing service systems.
We address the verification problem of networks of communicating pushdown systems modeling communicating parallel programs with procedure calls. Processes in such networks can read the control state of the other proce...
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ISBN:
(纸本)9783642029783
We address the verification problem of networks of communicating pushdown systems modeling communicating parallel programs with procedure calls. Processes in such networks can read the control state of the other processes according to a given communication structure (specifying the observability rights between processes). the reachability problem of such models is Undecidable in general. First, we define a class of networksthat effectively preserves recognizability (hence, its reachability problem is decidable). then, we consider networks where the communication structure can change dynamically during the execution according to a phase graph. the reachability problem for these dynamic networks being undecidable in general, we define a subclass for which it becomes decidable. then, we consider reachability when the switches in the communication structures are bounded. We show that this problem is undecidable even for one switch. then, we define a natural class of models for which this problem is decidable. this elms can be used in the definition of an efficient semi-decision procedure for the analysis of the general model of dynamic networks. Our techniques allowed to find bugs in two versions of a Windows NT Bluetooth driver.
During the design of complex networked systems, it is cruical to ensure the composability of the deployed applications and network protocols. Special care has to be taken to provide non-functional requirements like ba...
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ISBN:
(纸本)9781424427284
During the design of complex networked systems, it is cruical to ensure the composability of the deployed applications and network protocols. Special care has to be taken to provide non-functional requirements like bandwidth and latency. Existing solutions only tackle this problem during the design phase;later refactoring or added components are not covered, potentially causing QoS violations. We propose MLCCA, a multi-level architecture which complements the design-time composability checks with additional automatic checks performed at compile-time and at run-time. the required infrastructure is embedded into our communication middleware FAMOUSO, making it transparent to application developers. the architecture has been evaluated in a tele-operated mobile robot case study. If the QoS attributes could not be fulfilled due to refactoring or changed conditions, no communication was allowed by the middleware, ensuring that the application could enter a fail-safe state. No data was sent over insufficient channels. thus, our combination of FAMOUSO and MLCCA enables the sustainable deployment of complex networked systems.
there is a growing interest in using star topologies instead of buses as the communication infrastructure for highly-reliable distributed control systems, given the better dependability stars are supposed to provide. ...
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ISBN:
(纸本)9781424427284
there is a growing interest in using star topologies instead of buses as the communication infrastructure for highly-reliable distributed control systems, given the better dependability stars are supposed to provide. For the Controller Area Network (CAN), we developed a simplex and a replicated star called CANcentrate and ReCANcentrate respectively. In a previous work we modelled the dependability of the CAN bus and CANcentrate using Stochastic Activity networks (SANs). there we presented the first quantitative analysis of the error-containment benefits of a simplex star when considering permanent hardware faults. this paper quantitatively analyzes, for the first time, how a replicated star such as ReCANcentrate can improve both error-containment and reliability, also considering permanent hardware faults. We explain our modelling strategy using SANs and show some first and novel results.
Wireless communication and smart sensors and actuators pose means to sustainably improve automation technology. Unfortunately they also cause an abundance of new challenges regarding security and safety of the system....
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ISBN:
(纸本)9781424427284
Wireless communication and smart sensors and actuators pose means to sustainably improve automation technology. Unfortunately they also cause an abundance of new challenges regarding security and safety of the system. After introducing the security concepts, this paper discusses an engineering methodology to cope with security requirements in context of industrial automation. Two practical examples demonstrate how the solutions even for pretty similar scenarios can differ significantly. the proposed development flow promises a reliable objective engineering of proper system solutions. Key concepts of the flow are a holistic goal description and an iterative composition algorithm that inherently applies and extends existing knowledge.
the WirelessHART standard uses TDMA and channel hopping to control access to the network and to coordinate communication between network devices, in order to enhance reliability and to improve the throughput of the ne...
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ISBN:
(纸本)9781424427284
the WirelessHART standard uses TDMA and channel hopping to control access to the network and to coordinate communication between network devices, in order to enhance reliability and to improve the throughput of the network. A problem in utilizing multiple channels is that current devices are usually equipped with a single transceiver. thus, a node can only transmit or receive on one channel at a time. Moreover, contrary to today's wired control systems, if a single access point is used the communication becomes the bottle neck of the control system. therefore this paper presents how one may schedule the WirelessHART communication using two access points. Furthermore the paper describes a scheduling algorithm managing a multihop multi-channel networked control system based on the WirelessHART standard. A simulation example of a multihop multi-channel network is also shown, using the fixed packet lost utility of the Matlab/Simulink-based tool TrueTime.
Summary form only given. In regard to the emerging Web 2.0 service explosion the telecommunications landscape is evolving rapidly from a voice and messaging centric environment towards an open multimedia service and c...
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Summary form only given. In regard to the emerging Web 2.0 service explosion the telecommunications landscape is evolving rapidly from a voice and messaging centric environment towards an open multimedia service and content market. Whereas historically specific telecommunication services (such as voice telephony) have been provided in dedicated network environments (such as the PSTN/ISDN) with specific service delivery platforms (SDPs) in charge for the control of value added services (such as the intelligent network), we today see the notion of seamless interactive multimedia communication and information services, often referred to as X-Play services, on top of converging networks. this convergence of fixed and mobile telecommunicationnetworks withthe Internet is driving the definition and implementation of the so-called next generation network (NGN).
the concept of multi-hop CDMA cellular networks has received increasing attention now. It is a widely accepted assumption that using multi-hopping in cellular networks will increase the cellular throughput. there are ...
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the concept of multi-hop CDMA cellular networks has received increasing attention now. It is a widely accepted assumption that using multi-hopping in cellular networks will increase the cellular throughput. there are several advantages of MCN such as the improved signal quality and higher coverage. Finding an available relaying path is a critical prerequisite for the success of the multi-hop cellular networks and has a great impact on the network throughput. Most works use signal strength, distance and power consumption as routing criteria, but the effect of interference specially intercell interference does not take into account in routing algorithms. For this reason, in this paper interference is calculated at any receiver during the uplink, and a novel routing scheme based on minimum interference and best link gain in each hop, is proposed. Simulation results indicate that the routing algorithm based on our proposed metric results in higher throughput than the other metrics under a certain constraint.
In this paper we report our practical experience in benchmarking a System Biology Web Service, and investigate instability of its performance and the delays induced by the communication medium. We discuss the results ...
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In this paper we report our practical experience in benchmarking a System Biology Web Service, and investigate instability of its performance and the delays induced by the communication medium. We discuss the results of a statistical data analysis and discuss the causes affecting the Web Service performance. the uncertainty discovered in Web Services operations reduces the overall dependability of Service-Oriented Architecture and require specific resilience techniques.
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