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Proceedings Sixth Euromicro Workshop on Real-Time Systems

15-17 June 1994

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  • Proceedings Sixth Euromicro Workshop on Real-Time Systems

    Publication Year: 1994
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    Freely Available from IEEE
  • Pinwheel scheduling with three distinct numbers

    Publication Year: 1994, Page(s):174 - 179
    Cited by:  Papers (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (444 KB)

    Given a multiset of positive integers A={a1, a2 , ..., an}, the pinwheel problem is to find an infinite sequence over { 1, 2,..., n} such that there is at least one symbol i within any subsequence of length ai. The density of A is defined as ρ(A)=Σi=1n (1/ai). We limit ourselves to instances composed of three di... View full abstract»

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  • The derivation of scheduling algorithms from a timing model

    Publication Year: 1994, Page(s):180 - 185
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (352 KB)

    We first present a timing model for describing the temporal behaviour of a real-time application. Then, within this model, we specify formally the scheduling problem through a relation between so called temporal profiles. We show how this relation can be generically decomposed and implemented on different machine architectures View full abstract»

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  • Relating specified time tolerances to implementation performances

    Publication Year: 1994, Page(s):226 - 233
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (688 KB)

    Real-time systems require that the high-level control constructs used by the designer have a rigorously defined semantics specifying their actual temporal behavior, which unfortunately depends on implementation details that the high-level view tends to hide from the user. Moreover the real implementations only approximate the typical ideal properties; in some systems these approximations cannot be... View full abstract»

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  • Formal specification and verification of a real-time kernel

    Publication Year: 1994, Page(s):205 - 211
    Cited by:  Papers (3)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (412 KB)

    The paper presents a case study of application of the VDM formal method to specification and verification of a simple real-time kernel. Specifications of selected external services of the kernel are presented. Then the verification methodology is introduced by demonstrating its basic steps in relation to verification of a selected function-a process waiting for a signal on a condition variable. Th... View full abstract»

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  • On-line sporadic task scheduling in hard real-time systems

    Publication Year: 1994, Page(s):186 - 191
    Cited by:  Patents (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (460 KB)

    We propose a set of scheduling procedures for dealing with the sporadic task scheduling in a dynamic periodic system. For this we mean a system in which periodic tasks change their parameters dynamically (at run-time), in an unpredictable way. So, the off-line periodic task set will be different from the current periodic task set. It means that the task schedulability tests in such systems have to... View full abstract»

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  • Interprocessor-blocking independent static task allocation for shared-bus real-time multiprocessors

    Publication Year: 1994, Page(s):53 - 58
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (392 KB)

    In real-time systems, guaranteeing the schedulability of high priority tasks is more important than being able to schedule more tasks under resource constraints. The system bus in bus-based multiprocessors is a shared resource that is usually arbitrated by priority and fairness. This paper presents a new static task allocation strategy that takes into consideration the impact of bus arbitration po... View full abstract»

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  • A software architecture for complex real-time systems

    Publication Year: 1994, Page(s):110 - 115
    Cited by:  Patents (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (484 KB)

    The increasing use of computer-based control systems in complex applications requires modelling techniques which make it easier to develop and maintain these systems. One promising approach is to use object-orientation. The difficulty is that a traditional object-oriented programming language is most suitable for use in small projects and therefore is not directly scalable to a heterogeneous and d... View full abstract»

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  • Clock synchronization in virtual rings

    Publication Year: 1994, Page(s):72 - 77
    Cited by:  Papers (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (488 KB)

    A probabilistic algorithm for external clock synchronization is proposed. The algorithm works under the assumption that it is possible to identify a virtual ring among the servers involved, and does not require an upper bound to message transmission delays. The approach is probabilistic, since clock synchronization is not guaranteed, but the probability of success can be made arbitrarily close to ... View full abstract»

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  • Integration of RTL and precedence graphs with a static scheduler as verifier

    Publication Year: 1994, Page(s):22 - 25
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (300 KB)

    We present an approach to specification and verification of distributed hard real-time systems. By integrating RTL and precedence constraints, we combine the comprehensiveness of precedence graphs with the expressive power and proofability of RTL. Thus, our approach allows easy comprehension by the human designer and formal correctness. We propose to use a static scheduling algorithm based on heur... View full abstract»

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  • Scheduling in a hard real-time system with shared resources

    Publication Year: 1994, Page(s):234 - 239
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (500 KB)

    Hard real-time systems are those systems in which correctness depends on logical results of the computations as well as the times at which these results are produced. In a real-time context, concurrency control protocols for shared resources (as databases) must not only maintain the consistency constraints but also satisfy timing requirements of transactions. So, several protocols have been propos... View full abstract»

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  • Timing analysis and conditional scheduling in a real-time system design environment

    Publication Year: 1994, Page(s):214 - 219
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (524 KB)

    This paper presents an approach to carry out timing analysis and scheduling in a real-time system design environment for flexible manufacturing systems. It is built based on a formal model for specifying real-time systems using extended timed Petri nets. The designer uses the model to specify a design at a given level. The functional characteristics as well as timing properties of the design can t... View full abstract»

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  • Object-based design of embedded software using real-time operating systems

    Publication Year: 1994, Page(s):194 - 198
    Cited by:  Papers (3)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (320 KB)

    Embedded systems are used in everyday electronic consumer products and industrial equipment, e.g. television sets, radios, cars, and mobile phones. Rapid developments which have taken place in computer hardware and software technologies have led to the increased complexity of embedded systems. Promising results have been achieved in the development of complex information processing systems using o... View full abstract»

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  • Object-oriented enhancement of real-time software using a heterogeneous re-engineering approach

    Publication Year: 1994, Page(s):98 - 103
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (460 KB)

    A technique for incremental modernisation and enhancement of an existing procedural real-time software to an object-oriented one is presented. The incremental enhancement enables the real-time system designer to make use of the advantages of object-oriented paradigm: the resulting re-engineered software is more maintainable, reusable and configurable. In this approach, the object structure and add... View full abstract»

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  • Neural networks for multiprocessor real-time scheduling

    Publication Year: 1994, Page(s):59 - 64
    Cited by:  Papers (7)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (484 KB)

    In recent years, neural networks have become a popular area of research, especially after Hopfield and Tank opened the way for using neural networks for optimization purposes and surprised the scientific community by their paper (Biological Cybernetics, vol. 52, pp. 141-52, 1985) presenting a circuit to give approximate solutions for the classical traveling salesman problem in a few elapsed propag... View full abstract»

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  • UltraSMART: a scalable multiprocessor architecture for real time

    Publication Year: 1994, Page(s):118 - 123
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (532 KB)

    Concurrent Computer Corporation's UltraSMART (scalable multiprocessor architecture for real time) architecture is a busless distributed shared memory multiprocessor architecture that enables higher levels of performance and better real-time behavior than can be obtained with bus-based global shared memory multiprocessors. The paper describes UltraSMART, the UltraSMART-based MAXION multiprocessor s... View full abstract»

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  • A dynamic scheduling algorithm for semi-hard real-time environments

    Publication Year: 1994, Page(s):130 - 137
    Cited by:  Papers (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (620 KB)

    In many real-time systems, it is crucial for the application tasks to meet their specified deadlines, otherwise the tasks cause catastrophic results. Every task is generally periodic, and the value of its period depends on the dynamics of the process it controls. In addition, some additional time-critical tasks said to be sporadic can occur and require to be processed at unpredictable times. The p... View full abstract»

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  • Determining the worst-case blocking sequences for distributed real-time programs

    Publication Year: 1994, Page(s):4 - 9
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (340 KB)

    For detecting timing errors in a distributed real-time program (distributed real-time debugging) it is essential to know all combinations of execution paths where a given path experiences a worst-case blocking time through communication (server calls) among the subprograms. In this paper we deal with the subproblem of blocking sequences of server call pairs between 2 paths. For determining their w... View full abstract»

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  • The sequencing of data flow tasks in SIGNAL: application to active vision in robotics

    Publication Year: 1994, Page(s):80 - 85
    Cited by:  Papers (5)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (476 KB)

    Many applications of real-time systems feature a combination of “continuous” (possibly sampled) and discrete (sequencing and task control) behaviors, both reactive to the evolutions of the execution environment. In particular, robotics applications involve the programming of the control functions for each task, and the sequencing of such tasks at a higher level. In the framework of the... View full abstract»

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  • Dynamic scheduling for mobile robots

    Publication Year: 1994, Page(s):28 - 33
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (388 KB)

    This research concerns efficient multiprocessor threads-based implementation of reactive navigation for mobile robots. We present two important results: 1) Performance is improved significantly when CPU time allocated to individual navigational threads is adjusted dynamically according to a heuristic measure of their importance. 2) To implement this strategy, we present a multiprocessor scheduler ... View full abstract»

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  • Simple and robust: fuzzy for antislip

    Publication Year: 1994, Page(s):240 - 245
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (440 KB)

    The authors present the design of an intelligent control for industrial off road vehicles with hydrostatic power transmission to prevent wheel slippage. Timing and robustness were of particular interest. The authors employed a system of interconnected wheel processors, which house a two level local/global fuzzy control algorithm View full abstract»

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  • Algorithms for scheduling computations with secondary deadlines to minimize penalty

    Publication Year: 1994, Page(s):143 - 148
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (464 KB)

    In many real-time applications, some job allows part of its computation to be executed after its primary deadline but before an extended, or secondary deadline. We study the scheduling issues for real-time computations with secondary deadlines. We call the part of a computation which must be completed before the primary deadline its hard part, and the rest its soft part. The soft part of a computa... View full abstract»

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  • Can production systems be applied to hard real-time applications?

    Publication Year: 1994, Page(s):167 - 172
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (396 KB)

    Efficient match algorithms have influenced the acceptance of production systems in the industrial world. However, in embedded control systems they have not been applied intensively because of their non-deterministic run-time behavior. Until recently no method was known yielding rigorous upper bounds for run-time on match algorithms. Although the already published MLR (Micro Level Reasoner) method ... View full abstract»

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  • Animation in CONRAD: informal analysis of timing properties

    Publication Year: 1994, Page(s):220 - 225
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (404 KB)

    It is suggested that timing restrictions are the fundamental part of the specification of a time-critical system (limiting the possible design solution space), because most of the timing restrictions have been objectively determined by the object to be controlled and thus cannot be changed arbitrarily. Timing correctness in real-time systems means that process activations, data production and cons... View full abstract»

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  • Guaranteed deadlines with dynamic recovery blocks in distributed systems

    Publication Year: 1994, Page(s):199 - 204
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (468 KB)

    In a hard real-time system, a timing fault is said to occur when a real time task delivers its results too late. An deadline mechanism has been proposed to avoid timing faults in uniprocessor machines. Under this approach, every task is implemented with two algorithms: on one hand, a primary program produces a good quality service but in an unknown and possibly infinite length of time due to softw... View full abstract»

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