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Proceedings of the 4th International Workshop on Parallel and Distributed Real-Time Systems

15-16 April 1998

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  • Proceedings of the 4th International Workshop on Parallel and Distributed Real-Time Systems

    Publication Year: 1996
    Request permission for commercial reuse | PDF file iconPDF (76 KB)
    Freely Available from IEEE
  • Development and validation of network clock measurement techniques

    Publication Year: 1996, Page(s):65 - 68
    Cited by:  Papers (4)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (352 KB)

    Navy systems are inherently real time. As these systems evolve with the introduction of new requirements, technologies, and commercial off the shelf (COTS) equipment, they are evolving toward more distributed systems. A key component to the deployment of real time distributed systems in Navy applications is quality clock synchronization among the various computing platforms in the distributed syst... View full abstract»

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  • Modeling and simulation in reactive systems

    Publication Year: 1996, Page(s):27 - 34
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (876 KB)

    In currently-used paradigms for system development, knowledge about the objects in the system's environment is used to derive algorithms that relate events in the environment to actions. This results in implicit representation of the original knowledge in the operational system. In the majority of cases, there are only very limited mechanisms for controlling these built-in behaviours, whereas for ... View full abstract»

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  • User-level real-time network system on Real-Time Mach

    Publication Year: 1996, Page(s):172 - 179
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (916 KB)

    The paper presents the design and implementation of a user level real time network system in Real-Time Mach. Traditional network systems, which tend to focus on high performance and flexibility, are not suitable for real time communication. Our network system provides a framework for implementing real time network protocols which are able to bound end to end delay and throughput. We especially foc... View full abstract»

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  • Communication issues in heterogeneous embedded systems

    Publication Year: 1996, Page(s):180 - 183
    Cited by:  Papers (4)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (488 KB)

    The recent accelerated development of scalable computing systems has made possible the coordinated use of a suite of High Performance Computing (HPC) components for computationally demanding problems in embedded applications. These emerging Scalable Heterogeneous High Performance Embedded (SHHiPE) systems are designed using commercial off the shelf (COTS) modules. Our current interest is to employ... View full abstract»

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  • Benchmarking of real-time high-performance computing systems

    Publication Year: 1996, Page(s):198 - 199
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (224 KB)

    The real-time high performance computing community needs to establish an industry-supported benchmarking effort. This effort should specify two sets of benchmarks: one at an application level and one at a functional level, or so-called “compact” applications. A common set of performance metrics incorporating the embedded physical attributes of systems must be defined. Both system vendo... View full abstract»

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  • PARSYNTH: a case study on implementing a real-time digital audio synthesizer

    Publication Year: 1996, Page(s):143 - 146
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (372 KB)

    Current real time systems with heavy computation loads and unpredictable event sequences are being constructed with mechanisms and policies that permit them to adjust to new environmental conditions. We present a framework for the real time synthesis of multimedia artifacts and an application PARSYNTH, which utilizes the libraries specified in the framework. Our results indicate that PARSYNTH gene... View full abstract»

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  • Reengineering a single threaded embedded missile application onto a parallel processing platform using metaH

    Publication Year: 1996, Page(s):57 - 64
    Cited by:  Papers (4)  |  Patents (5)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (752 KB)

    Describes a software/hardware architectural transformation of a single-threaded, cyclic executive-based missile application to a multitasking, distributed application using MetaH (which builds a multiprocessor executive, based on rate monotonic theory, that binds with hand-generated Ada code and code generated from the ControlH algorithm specification language and code generator). The benefits of ... View full abstract»

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  • Rare event simulation with an adaptive “RESTART” method in a Petri net modeling environment

    Publication Year: 1996, Page(s):229 - 234
    Cited by:  Papers (3)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (552 KB)

    For the performability evaluation of complex soft real time systems, simulation often remains the only feasible method. Simulation experiments tend to be very time consuming if rare events have to be considered. The paper describes a fast simulation approach for rare events implemented in a Petri net tool. The technique is based on the recently developed RESTART method, which is applicable for rar... View full abstract»

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  • An embedded real-time SIMD processor array for image processing

    Publication Year: 1996, Page(s):131 - 134
    Cited by:  Papers (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (312 KB)

    The paper presents an overview of the SuperSPAR (Systolic Processor Array) architecture and chip set. The SuperSPAR was designed by Lockheed Martin to bring the benefits of massively parallel SIMD processing to the embedded systems domain. The system philosophy focused on building a hierarchy of scaleable subarray modules allowing systems to be configured by “plugging together” any num... View full abstract»

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  • Inter- and intra-processor synchronizations in multiprocessor real-time kernel

    Publication Year: 1996, Page(s):69 - 74
    Cited by:  Papers (5)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (660 KB)

    In multiprocessor systems the worst case execution time of a task that exclusively accesses a shared resource is unavoidably prolonged as the number of contending processors is increased. In case of function distributed multiprocessors, because many of the tasks can be processed without synchronizing or communicating with other processors, it is advantageous that the worst case behavior of such ta... View full abstract»

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  • An engineering approach to decomposing end-to-end delays on a distributed real-time system

    Publication Year: 1996, Page(s):244 - 251
    Cited by:  Papers (14)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (648 KB)

    We propose an adequate engineering technique for decomposing end-to-end delays in distributed real time systems. Our technique greatly simplifies the real time system design process by turning a global distributed scheduling problem into a set of single processor scheduling problems with local deadlines. The deadline decomposition is done using critical scaling factor (J. Lehoczky et al., 1989) as... View full abstract»

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  • Distributed real-time optimistic concurrency control protocol

    Publication Year: 1996, Page(s):122 - 125
    Cited by:  Papers (4)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (428 KB)

    Although many recent studies have suggested that optimistic concurrency control (OCC) with dynamic adjustment of serialization order (DASO) is more suitable than two phase locking (2PL) for real-time database systems (RTDBS), most of the protocols proposed for DRTDBS are based on 2PL. When OCC with DASO is extended to DRTDBS, a number of issues have to be resolved. These include the heavy overhead... View full abstract»

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  • Solving hard real-time scheduling problems on a single processor

    Publication Year: 1996, Page(s):81 - 86
    Cited by:  Patents (4)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (460 KB)

    Many applications e.g. from operations research, or areas like operating systems or control systems, deal with sets of activities or tasks that are of real time character, i.e. certain deadlines have to be obeyed in order to guarantee the correct function of the application. In scheduling theory, algorithms are developed with-depending on the particular requirements of the application-the objectiv... View full abstract»

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  • Cooperative transactions for real-time databases

    Publication Year: 1996, Page(s):110 - 117
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (884 KB)

    Transactions in areas such as real time databases and multimedia databases not only compete, but also cooperate. We propose a model for transactions to cooperate through rules and task communication and synchronization. In our model, transactions manipulate persistent and transient data objects. With event condition action (ECA) rules and three additional non ECA rules as tools, our model provides... View full abstract»

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  • Scheduling periodic distributed hard real-time tasks

    Publication Year: 1996, Page(s):101 - 104
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (396 KB)

    We present several efficient online and offline strategies for assigning periodic tasks to the nodes of a distributed system, such that the tasks can be feasibly scheduled by the node using some local static/dynamic priority assigning rule. We describe rules that lead to a near optimal utilization factor. Strategies are given for approximation algorithms and the approach leads to a high guarantee ... View full abstract»

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  • A platform for real-time visualization and interactive simulation of large multimedia networks

    Publication Year: 1996, Page(s):47 - 52
    Cited by:  Papers (4)  |  Patents (4)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (664 KB)

    Presents a platform for developing and evaluating control systems for emerging multimedia networks. The platform allows us to closely approximate the functional and dynamic behavior of network control systems. By providing support for real-time visualization and interactive emulation, it can be used to study multimedia networks in various scenarios, such as different load patterns, network sizes a... View full abstract»

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  • Heterogeneous parallel architecture for improving signal processing performance in Doppler blood flow instrumentation

    Publication Year: 1996, Page(s):135 - 138
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (356 KB)

    The work presents a heterogeneous parallel approach, for implementing a model based spectral estimation method, based on the modified covariance parametric algorithm. A Heterogeneous Processing Node (HPN) has been developed, which combines the communications ability of the transputer with a high performance signal processing of a DSP, in order to improve the time performance in parametric spectral... View full abstract»

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  • Modeling real-time distributed software systems

    Publication Year: 1996, Page(s):11 - 18
    Cited by:  Papers (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (752 KB)

    The “architecture” of a software system refers to its highest-level modular decomposition and the interrelationship patterns between its modules. An architecture serves as a blueprint for implementation and also as the chief determinant of a system's ability to evolve. Consequently, there is an increased interest in methods for specifying and validating software architectures. One such... View full abstract»

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  • Establishing a real-time distributed benchmark

    Publication Year: 1996, Page(s):200 - 201
    Cited by:  Papers (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (184 KB)

    There are currently very few well-known approaches for performing measurements on real-time distributed environments, none of which can be considered as widely accepted at this point in time. The establishment of an acceptable approach to evaluation for real-time distributed environments will be a far-reaching enterprise. There is much debate about what constitutes a valid performance level evalua... View full abstract»

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  • Semantics for an actor-based real-time language

    Publication Year: 1996, Page(s):223 - 228
    Cited by:  Papers (6)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (548 KB)

    We give formal semantics for a distributed concurrent object oriented real time programming language based on a variant of the actor model which includes an extention enabling the specification of time constraints on message invocation. Real time semantics must capture both the qualitative and quantitative aspects of the language, and provide a meaning for the real time constructs. The real time s... View full abstract»

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  • Entity-life modeling in a distributed environment

    Publication Year: 1996, Page(s):35 - 41
    Cited by:  Papers (1)  |  Patents (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (696 KB)

    Distributed systems may have local concurrency if the operating system at a node supports multiple tasks. There may also be global concurrency with sequential processes spanning several nodes. Entity-life modeling (ELM) is a method to pattern software concurrency after the concurrency inherent in the problem domain. The events that occur in the problem are partitioned into sequences called threads... View full abstract»

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  • Asynchronous mode of FDDI for real-time multimedia communication

    Publication Year: 1996, Page(s):184 - 187
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (396 KB)

    FDDI network is a network that can provide real time message delivery. It supports two classes of messages: synchronous class and asynchronous class. Guaranteeing deadlines of real time messages with FDDI synchronous mode has been studied extensively. However, most existing FDDI products support asynchronous message transmission only. We develop an analytic method for guaranteeing real time multim... View full abstract»

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  • Relaxed serializability based on consistent states for real-time database applications

    Publication Year: 1996, Page(s):126 - 129
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (396 KB)

    Serializability, the standard notion of correctness, has limitations in real-time database systems because its strict logical consistency. For certain real-time applications, serializability may not be necessary for concurrent execution and different correctness criteria may be applied to different applications depending on the semantics and the requirements of transactions in the applications. Th... View full abstract»

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  • An environment for incremental development of distributed extensible asynchronous real-time systems

    Publication Year: 1996, Page(s):43 - 46
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (412 KB)

    Incremental, parallel development of distributed real-time systems is difficult. Architectural techniques and software tools developed at the Jet Propulsion Laboratory's (JPL's) Flight System Testbed (FST) make feasible the integration of complex systems in various stages of development. In particular, two techniques are used: a strict layering architecture for organization of independent subsyste... View full abstract»

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