In multimode distributedsystems, active task sets are assigned to their distributed components for realizing one or more functions. Many of these systems encounter runtime task variations at the input and across the ...
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In multimode distributedsystems, active task sets are assigned to their distributed components for realizing one or more functions. Many of these systems encounter runtime task variations at the input and across the system while processing their tasks in realtime. Very few efforts have been made to address energy efficient scheduling in these types of distributedsystems. In this paper, we propose an analytical model for energy efficient scheduling in distributedreal-time embedded systems to handle time-varying task inputs. A new slack distribution scheme is introduced and adopted during the schedule of the task sets in the system. The slack distribution is made according to the service demand at the nodes which affects the energy consumption in the system. The active component at a node periodically determines the service rate and applies voltage scaling according to the dynamic traffic condition observed at various network nodes. The proposed approach uses a comprehensive traffic description function at nodes and provides adequate information about the worst-case traffic behavior anywhere in the distributed network, thereby enhancing the system power management capabilities. We evaluate the proposed technique using several benchmarks employing an event driven simulator and demonstrate its performance for multimode applications. Experimental results indicate significant energy savings in various examples and case studies.
Modern aircraft require complex systems of complementary sensors for the achievement of precise and dynamic on-line flight measurements. For the computation, transmission and storage of sensor data a distributed infor...
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Modern aircraft require complex systems of complementary sensors for the achievement of precise and dynamic on-line flight measurements. For the computation, transmission and storage of sensor data a distributed information system is needed which has to respect hard real-time demands. In this paper the demands of an aircraft sensor system on the components of the distributed information system are analysed allowing the allocation and partitioning of the tasks to the resources. Simulation experiments are used to investigate the real-time behaviour of the whole information system, consisting of several RISC-processors, DRAMs and bus systems. The bus systems are divided into parallel and serial buses;the serial field bus: system is realized by PROFIBUS. The real-time behaviour of PROFIBUS is additionally analysed by hardware experiments. (C) Elsevier, Paris.
The sequential method is easy to integrate with existing large-scale alternating current(AC)power flow solvers and is therefore a common approach for solving the power flow of AC/direct current(DC)hybrid *** this pape...
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The sequential method is easy to integrate with existing large-scale alternating current(AC)power flow solvers and is therefore a common approach for solving the power flow of AC/direct current(DC)hybrid *** this paper,a highperformance graph computing based distributedparallel implementation of the sequential method with an improved initial estimate approach for hybrid AC/DC systems is *** proposed approach is capable of speeding up the entire computation process without compromising the accuracy of ***,the AC/DC network is intuitively represented by a graph and stored in a graph database(GDB)to expedite data *** the interconnection of AC grids via high-voltage direct current(HVDC)links,the network is subsequently partitioned into independent areas which are naturally fit for distributed power flow *** each area,the fast-decoupled power flow(FDPF)is employed with node-based parallel computing(NPC)and hierarchical parallel computing(HPC)to quickly identify system ***,to reduce the alternate iterations in the sequential method,a new decoupled approach is utilized to achieve a good initial estimate for the Newton-Raphson *** the improved initial estimate,the sequential method can converge in fewer ***,the proposed approach allows for significant reduction in computing time and is able to meet the requirement of the real-time analysis platform for power *** performance is verified on standard IEEE 300-bus system,extended large-scale systems,and a practical 11119-bus system in China.
This paper describes a toolset, whose objective is to provide full support for the analysis and testing of temporal behavior in the development of parallelrealtimesystems. The development approach supported by the t...
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ISBN:
(纸本)0818683325
This paper describes a toolset, whose objective is to provide full support for the analysis and testing of temporal behavior in the development of parallelrealtimesystems. The development approach supported by the toolset is based on an incremental prototyping technique combined with successive analyses and tests of the temporal behavior of prototypes carried out along the development cycle. The toolset is composed of three main tools: a prototyper, a monitor and a visualizer/analyzer. Most current monitoring and analysis tools are oriented to measure and visualize the behavior of software entities (mainly processes) and the utilization of hardware resources, that is, the elements of the system design. In addition to this, this toolset incorporates a graph based model that provides a functional view of the behavior. This is expressed in terms of the sequences of activities executed by the system in respond to the main external environment events (reactive aspect of real-timesystems). Moreover, the toolset provides a powerful means to design and test the system under development in an incremental manner.
The real-time CORBA and minimumCORBA specifications are important steps towards defining standard-based middleware which can satisfy real-time requirements in an embedded system. To reach a broad acceptance in the rea...
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The real-time CORBA and minimumCORBA specifications are important steps towards defining standard-based middleware which can satisfy real-time requirements in an embedded system. To reach a broad acceptance in the real-time and embedded community, these specifications have to facilitate the utilization of traditional real-time networks for embedded systems. The Controller Area Network (CAN) is one of the most important networks in the field of real-time embedded systems. Consequently, this paper presents a CAN-based connection-oriented communication model and its integration into real-time CORBA. In order to make efficient use of the advantages of CAN, we present a new inter-ORB protocol, which uses smaller message headers for CAN and maps the CAN priorities to bands of CORBA priorities. We also present design and implementation details and evaluate the performance of the new inter-ORB protocol. (c) 2004 Elsevier Inc. All rights reserved.
Control algorithms for accurate and fast moving robots require computations based on the complete dynamic model of the robot. These computations are time consuming due to the high degree of coupling between robot link...
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Control algorithms for accurate and fast moving robots require computations based on the complete dynamic model of the robot. These computations are time consuming due to the high degree of coupling between robot links and the nonlinear dependence of the robot's dynamic characteristics on orientation of the links. A method for processing the dynamic control equations in real-time by using parallel computation is described. The recursive Newton-Euler equations are distributed over multiple computing elements, one for each joint. Concurrency is achieved by substituting "predicted" values for the actual values of variables involved in the recursive equations. The method has been simulated and compared to other approaches to this problem such as simplification of the dynamic equations. The experimental results have shown that the errors introduced by prediction are relatively small and compare very favorably to other techniques. The computer architecture and algorithms presented offer a practical way to implement the control algorithms with relatively inexpensive computing devices.
Communication technologies are being continuously developed to provide improved support of real-time links for an industrial Internet of Things. This article considers a general and flexible distributed control archit...
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Communication technologies are being continuously developed to provide improved support of real-time links for an industrial Internet of Things. This article considers a general and flexible distributed control architecture over real-time links. No bounds are assumed on the value of delays that are modeled as random variables. An accurate modeling and analysis framework is provided and the exact value of a control performance cost function is calculated. The results provide the required tools for optimization-based design of distributed networked control systems. A case study is presented in which networked controllers are designed based on the consensus algorithm for coordination of multiple parallel power electronic converters. It is shown that consideration of the communication effects in the controller design process is crucial for achieving superior performance.
The nearest-neighbor method can successfully be applied to correct possible errors induced into bit strings transmitted over noisy communication channels or to classify samples into a predefined set of categories. The...
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The nearest-neighbor method can successfully be applied to correct possible errors induced into bit strings transmitted over noisy communication channels or to classify samples into a predefined set of categories. These two applications are investigated under real-time constraints, when the deadlines imposed can dramatically alter the quality of the solution unless a parallel model of computation (in these cases, a linear array of processors) is used. We also study a class of real-time computations, referred to as reactive real-timesystems, that are particularly sensitive to the first time constraint imposed. (C) 2005 Elsevier Inc. All rights reserved.
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 ...
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Energy consumption is a critical issue in parallel and distributed embedded systems. We present a novel algorithm for energy efficient scheduling of Directed Acyclic Graph (DAG) based applications on Dynamic Voltage S...
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Energy consumption is a critical issue in parallel and distributed embedded systems. We present a novel algorithm for energy efficient scheduling of Directed Acyclic Graph (DAG) based applications on Dynamic Voltage Scaling (DVS) enabled systems. Experimental results show that our algorithm provides near optimal solutions for energy minimization with considerably smaller computational time and memory requirements compared to an existing algorithm that provides near optimal solutions. (C) 2009 Elsevier Inc. All rights reserved.
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