In this paper, we study the problem of scheduling periodic task sets defined under Quality of Service (QoS) constraints. In our approach, periodic tasks allow occasional skips of instances. A new algorithm, called RLP...
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ISBN:
(纸本)0769523463
In this paper, we study the problem of scheduling periodic task sets defined under Quality of Service (QoS) constraints. In our approach, periodic tasks allow occasional skips of instances. A new algorithm, called RLP (Red tasks as Late as Possible) based on the Skip-Over model and the EDL (Earliest Deadline as Late as Possible) scheduling strategy, is proposed to enhance the QoS observed for periodic tasks, i.e, the ratio of periodic tasks which complete before their deadline. We prove that our results are never worse than those obtained in previous work. Experimental results also show significant improvement achieved by our algorithm over RTO and BWP.
real-timesystems could be modeled using AOP based on UML. Timing requirements could be separated from the system according the separation of concerns techniques, expressed as a time-aspect independence of the system,...
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ISBN:
(纸本)0769523463
real-timesystems could be modeled using AOP based on UML. Timing requirements could be separated from the system according the separation of concerns techniques, expressed as a time-aspect independence of the system, and designed occurrence. So a timing model could be created to describe the time of the system. Finally the timing model could be woven into the system to compose a real-time system based on the AOP technology only when needed for a particular application. Also UML had been extended to express AOP and the time model. the real-timesystems could be modeled from the static structure, dynamic behaviors and weaving of the time-aspect, and an elevator case had been given as an example.
Designing and constructing real-time Distributed Industrial Vision systems (RT-DIVS) from scratch is very complicated task RT-DIVS has Conflicting requirements such as reasonable development cost, ease of use, reusabl...
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ISBN:
(纸本)0769523463
Designing and constructing real-time Distributed Industrial Vision systems (RT-DIVS) from scratch is very complicated task RT-DIVS has Conflicting requirements such as reasonable development cost, ease of use, reusable code and high performance. the success key in building such systems is to recognize the need for middleware software. Middleware plays a major role in developing distributed systems efficiently. real-time Publish-Subscribe (RTPS) model is one of the latest developments in real-time middleware technologies. Network Data Distribution Service (NDDS) is RTPS middleware developed by real-time Innovation (RTI). NDDS is widely used in real-time distributed and embeddedsystems for mission critical applications. the research work presented in this paper discusses the employment of NDDS for RT-DIVS and the advantages of NDDS's Quality of Service (QoS) policies in covering the requirements of RT-DIVS. An experimental test set-up is used to verify the NDDS's performance for RT-DIVS. Tests results show that RTPS middleware (and NDDS specifically) is suitable for soft and firm timelines requirements for distributed industrial vision systems.
Correctness of a real-time system depends on its computation as well as its timeliness and its reliability. In recent years, researches have focused on verifying correctness of a real-time system during runtime by mon...
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ISBN:
(纸本)0769523463
Correctness of a real-time system depends on its computation as well as its timeliness and its reliability. In recent years, researches have focused on verifying correctness of a real-time system during runtime by monitoring its execution and checking it against its formal specifications. Such verification method is called Runtime Verification. Most existing runtime verification tools verify computation correctness using qualitative property specifications but do not verify timeliness nor reliability correctness. In this paper, we investigate the verification on timeliness and reliability correctness by offering quantitative and probabilistic property specifications and implementing efficient verifiers.
Withthe advent of miniaturized sensing technology, it has become possible to envision smart structures containing millions of sensors embedded in concrete for autonomously detecting and locating incipient damage. Whe...
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ISBN:
(纸本)0769523463
Withthe advent of miniaturized sensing technology, it has become possible to envision smart structures containing millions of sensors embedded in concrete for autonomously detecting and locating incipient damage. Where are we today in our march towards this vision of autonomous structural health monitoring (SHM) using networked embedded sensing? In this paper, we summarize some of the systems we have developed towards this vision. Wisden is a wireless sensor network that allows continuous monitoring of structures and NetSHM is a programmable system that allows civil engineers to implement and deploy SHM techniques without having to understand the intricacies of wireless sensor networking. We highlight our experiences in developing these systems, and discuss the implications of our experiences on the achievability of the overall vision.
Advanced microarchitectural features such as caches and branch prediction mechanisms supporting speculative execution are becoming commonplace within modem microprocessors. For developers of real-timesystems, these m...
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ISBN:
(纸本)0769523463
Advanced microarchitectural features such as caches and branch prediction mechanisms supporting speculative execution are becoming commonplace within modem microprocessors. For developers of real-timesystems, these mechanisms present predictability problems. Previous work has demonstrated accurate analysis for instruction caches, data caches, and branch prediction mechanisms is possible. However the integration of these individual analysis methods is difficult to do without large increases in computational complexity or the introduction of pessimism regarding the Worst-Case Execution time (WCET) estimate. In this paper we discuss how a previously published analysis method for branch predictors can be integrated with instruction pipeline analysis.
Context aware middleware infrastructures have traditionally been implemented with a modular approach to allow different components to work cooperatively and supply context synthesis and provision services. In this pap...
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ISBN:
(纸本)0769523463
Context aware middleware infrastructures have traditionally been implemented with a modular approach to allow different components to work cooperatively and supply context synthesis and provision services. In this paper, we discuss the important requirements that arise when such a middleware is deployed in a distributed environment and present the design and implementation of Context Aware Middleware for Ubiquitous systems (CAMUS(1)) with which the authors have attempted to meet those requirements. Issues related to distributed coordination within the middleware in terms of component discovery and management and multiple context domains are also discussed.
Most prior theoretical research on partitioning algorithms for real-time multiprocessor platforms has focused on ensuring that the cumulative computing requirements of the tasks assigned to each processor does not exc...
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ISBN:
(纸本)0769523463
Most prior theoretical research on partitioning algorithms for real-time multiprocessor platforms has focused on ensuring that the cumulative computing requirements of the tasks assigned to each processor does not exceed the processor's processing power However many multiprocessor platforms have only limited amounts of local per-processor memory;if the memory limitation of a processor is not respected, thrashing between "main" memory and the processor's local memory may occur during run-time and may result in performance degradation. We formalize the problem of task partitioning in a manner that is cognizant of both memory and processing capacity constraints as the memory constrained multiprocessor partitioning problem, prove that this problem is intractable, and present efficient algorithms for solving it under certain - well-defined - conditions.
Wireless sensor network (WSN) has many promising applications. One of the most challenging technical issues for sensor network design is to enable ultra low power consumption communication. In this paper we propose a ...
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ISBN:
(纸本)0769523463
Wireless sensor network (WSN) has many promising applications. One of the most challenging technical issues for sensor network design is to enable ultra low power consumption communication. In this paper we propose a packet compression mechanism, namely EasiPC, as a new power management technique for WSN. Withthis mechanism, the lengths of data packets are shortened significantly due to the effective reduction of redundant information. As a consequence the energy required for transporting packets is saved too. Experiments carried out on WSN platform developed in-house show that this packet compression mechanism is both feasible and effective. Additional benefits introduced by this packet compression mechanism include reduced transmission delays, reduced channel accessing collisions, as well as enhanced channel utilization.
In this paper we propose a simple model for component based real-timesystems using duration automata. For this simple model we propose an algorithm for solving the emptiness problem using black-box testing for compon...
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