Describes an approach for extending distributed system specifications. These specifications are structured as a parallel composition of subsystem specifications. The approach consists of building a new specification S...
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This paper presents a scheduling technique for guaranteeing end-to-end timing constraints. Applications are structured as a set of tasks which are the sequence of actions to produce an output. Task is decomposed into ...
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This paper presents a scheduling technique for guaranteeing end-to-end timing constraints. Applications are structured as a set of tasks which are the sequence of actions to produce an output. Task is decomposed into subtasks and shares subtasks with other tasks. According to the proposed scheduling technique, for each instance of a task, the sequence of subtasks is determined off-line and then called by the task sequentially at runtime. This technique avoids unnecessary execution of shared tasks and satisfies precedence constraints between subtasks even in overload situations.
As an approach to reduce the variation in functional brain images between different individuals we tested different methods for an elastic image deformation by polynomial warping. The polynomials vary in degree and nu...
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As an approach to reduce the variation in functional brain images between different individuals we tested different methods for an elastic image deformation by polynomial warping. The polynomials vary in degree and number and distribution of the grid-points. The computations show that image warping with second degree polynomials and equally distributed grid-points increases most efficiently the similarity of shape and gray-values in the images whereas the tested higher degree polynomials are not useful.
In Profibus master stations poll data from slave stations using the cyclic service-CSrd (Cyclic Send and Request Data with Reply). Because the polling-interval determines the data sampling interval, it is important fo...
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In Profibus master stations poll data from slave stations using the cyclic service-CSrd (Cyclic Send and Request Data with Reply). Because the polling-interval determines the data sampling interval, it is important for the Profibus user to be able to know the maximum polling-interval of a cyclic service. In this paper we develop a formula for determining the maximum polling-interval of a cyclic service. Furthermore, if the polling-interval of a cyclic service cannot be met, then we can repeat the corresponding cyclic service in a poll list to reduce the polling-interval. However, how are the repeated cyclic services to be positioned in the poll list? The approach we use is an equi-distance one.
A distributed real-time computer system consists of several processing nodes which are interconnected by communication channel. For a safety critical application the real-time computer system should maintains timely a...
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A distributed real-time computer system consists of several processing nodes which are interconnected by communication channel. For a safety critical application the real-time computer system should maintains timely and dependable services despite component failures or environmental changes. In this paper we present a framework of an adaptable distributed real-time computer system which can adjusts its operating strategies in response to changing application environments or variation in the fault patterns. The proposed adaptable real-time system (ARTS) is based on the integration of the scheduling strategy using imprecise technique (IT) with the fault tolerance mechanism. In our simulation study the performance of an ARTS of a controller area network (CAN) based distributed system is evaluated as to whether the timing constraints of the automotive benchmark signals can be satisfied for normal, overload, and degraded operational modes. Our investigation also shows that the quality of service maintained by the ARTS can be further improve by varying the workload.
In the studies of real-time concurrency control protocols (RT-CCPs), it is always assumed that earliest deadline first (EDF) is employed as the CPU scheduling algorithm. However, using purely (ultimate) deadline for p...
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In the studies of real-time concurrency control protocols (RT-CCPs), it is always assumed that earliest deadline first (EDF) is employed as the CPU scheduling algorithm. However, using purely (ultimate) deadline for priority assignment may not be suitable for distributed real-time database systems (DRTDBS) in which there exist different kinds of transactions, such as global and local transactions. In order to improve the performance, different priority assignment heuristics have to be used. In this paper, we have investigated the performance of different priority assignment heuristics for sub-transactions in DRTDBS with optimistic concurrency control (OCC) protocol. If is found that the heuristics, which are suitable for distributed real-time systems, are not suitable for DRTDBS. We find that our proposed heuristic, which considers both deadline constraint and data contention, can give the best performance.
A shape recognition system used to navigate a disassembly robot is being described. The task that the robotics system has to solve is that of dismantling TV sets. The image processing module operates on 2D and 3D data...
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A shape recognition system used to navigate a disassembly robot is being described. The task that the robotics system has to solve is that of dismantling TV sets. The image processing module operates on 2D and 3D data and uses a combination of image pre-processors and a RAM net architecture implemented in hardware.
Parallel and distributed computer architectures are increasingly being considered for application in a wide variety of computationally intensive embedded systems. Many such applications impose highly dynamic demands f...
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Parallel and distributed computer architectures are increasingly being considered for application in a wide variety of computationally intensive embedded systems. Many such applications impose highly dynamic demands for resources (processors, memory, and communication network), because their computations are data-dependent, or because the applications must constantly interact with a rapidly changing physical environment, or because the applications themselves are adaptive. This paper presents a set of dynamic resource allocation techniques aimed at maintaining high levels of application performance in the presence of varying resource demands. It focuses on a class of applications structured as multiple pipelines of data-parallel stages, as this structure is common to many sensor-based applications. We discuss the issues involved in resource management for such applications, and present preliminary results from our implementations on Intel Paragon. Our approach uses feedback control-a real-time monitoring system is used to detect significant performance shortfalls, and resources are reallocated among the application components in an attempt to improve performance. The main contribution of this work is that it combines real-time monitoring of an application's performance with dynamic resource allocation, and focuses on practical implementations rather than simulation and analysis.
A situation-based selective video recording system for a short term memory aid is proposed. The system selectively records the images of events which happened in one39;s daily life based on sensor observation of the...
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A situation-based selective video recording system for a short term memory aid is proposed. The system selectively records the images of events which happened in one's daily life based on sensor observation of the user situation. The user wears sensors to monitor the environment and the action of the user himself. Selected scenes viewed with a head-mounted camera are recorded with situation information. This paper reports the system overview and some field experiments.
The mechanisms employed to detect motion by a variety of biological systems have been investigated for many years and a number of models that explain different aspects of these systems have been developed. Most of the...
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The mechanisms employed to detect motion by a variety of biological systems have been investigated for many years and a number of models that explain different aspects of these systems have been developed. Most of the models have been developed to explain aspects of wide field operation of motion detector arrays. This paper investigates suitability of these model as a front end to a system that requires local motion information. Results of simulations of different motion detection models using real scenes captured using a video camera are also presented.
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