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imprecise computation Based Real-time Fault Tolerant Implementation for Model Predictive Control

Journal of Donghua University(English Edition) 2006年第1期23卷 148-150页

作者：周平方谢剑英 Department of Automation Shanghai Jiaotong University Shanghai 200030

Model predictive control (MPC) could not be deployed in real-time control systems for its computation time is not well defined. A real-time fault tolerant implementation algorithm based on imprecise computation is proposed for MPC, according to the solving process of quadratic programming (QP) problem. In this algorithm, system stability is guaranteed even when computation resource is not enough to finish optimization completely. By this kind of graceful degradation, the behavior of real-time control systems is still predictable and determinate. The algorithm is demonstrated by experiments on servomotor, and the simulation results show its effectiveness.

关键词： model predictive control fault tolerance imprecise computation real-Time control

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imprecise computation technique to schedule AND/OR tasks with global end-to-end deadline in distributed real-time systems

Imprecise computation technique to schedule AND/OR tasks wit...

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SICE 2003 Annual Conference

作者： El-Haweet, WA El-Meligy, HH Abd El-Salam, I Alexandria Univ Fac Engn Comp Sci & Automat Control Dept Alexandria Egypt

ISBN: (纸本)0780383524

Directed Acyclic Graphs DAGs are used to represent AND/OR precedence constraint systems where AND tasks are ready to execute when all of their direct predecessors are completed and OR tasks are ready to execute when one or more but not necessarily all of their direct predecessors are completed. A proposed imprecise computation Technique ICT is introduced to maximize the solution quality within the available time. To examine and evaluate ICT, a Random Graph Generator algorithm RGG is created to provide a wide range of random DAGs to be used in the simulation experiments.

关键词： AND/OR precedence constraints directed acyclic graphs skipped and unskipped scheduling imprecise computation dependability design-to-time real-time scheduling

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Mapping imprecise computation tasks on cyber-physical systems

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PEER-TO-PEER NETWORKING AND APPLICATIONS 2019年第6期12卷 1726-1740页

作者： Mo, Lei Kritikakou, Angeliki Univ Rennes INRIA CNRS IRISA F-35042 Rennes France

By allocating a set of tasks onto a set of nodes and adjusting the execution time of tasks, task mapping is an efficient approach to realize distributed computing. Cyber-Physical Systems (CPS), as a particular case of distributed systems, raise new challenges in task mapping, because of the heterogeneity and other properties traditionally associated with Wireless Sensor and Actuator Networks (WSAN), including shared sensing, acting and real-time computing. In addition, many of the real-time tasks of CPS can be executed in an imprecise way. Such systems accept an approximate result as long as the baseline Quality-of-Service (QoS) is satisfied and they can execute more computations to yield better results, if more system resources is available. These systems are typically considered under the imprecise computation (IC) model, achieving a better tradeoff between QoS and limited system resources. However, determining a QoS-aware mapping of these real-time IC-tasks onto the nodes of a CPS creates a set of interesting problems. In this paper, we firstly propose a mathematical model to capture the dependency, energy and real-time constraints of IC-tasks, as well as the sensing, acting, and routing in the CPS. The problem is formulated as a Mixed-Integer Non-Linear Programming (MINLP) due to the complex nature of the problem. Secondly, to efficiently solve this problem, we provide a linearization method that results in a Mixed-Integer Linear Programming (MILP) formulation of our original problem. Finally, we decompose the transformed problem into a task allocation subproblem and a task adjustment subproblem, and, then, we find the optimal solution based on subproblem iteration. Through the simulations, we demonstrate the effectiveness of the proposed method.

关键词： Cyber-physical systems Task mapping imprecise computation Problem linearization and decomposition

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Algorithms for real-time scheduling of error-cumulative tasks based on the imprecise computation approach

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JOURNAL OF SYSTEMS ARCHITECTURE 2000年第7期46卷 587-600页

作者： Castorino, A Ciccarella, G Telesoft SPA I-00040 Rome Italy Univ Roma La Sapienza Dept Elect Engn I-00184 Rome Italy Telecom Italia SPA I-00125 Rome Italy Univ Aquila Dept Elect Engn I-67040 Laquila Italy

This paper presents several algorithms for real-time scheduling that have been developed following an approach known as imprecise computation. This technique prevents timing faults (i.e., results not produced in time) by offering an approximate result of an acceptable quality whenever the exact result of the desired quality cannot be obtained in time. in this work we focused our attention on the problem of scheduling a set of real-time error-cumulative periodic tasks for which errors in different periods have cumulative effects, making it necessary to generate timely, precise results sometimes. This problem is particularly relevant in applications such as route tracking and real-time control of complex industrial plants. The adopted approach consists in applying a transformation of the set of error-cumulative tasks into a set of error-noncumulative tasks that can be easily scheduled by means of an optimal algorithm like the earliest deadline first. This approach permits to obtain scheduling algorithms for some specific, but quite significant, problems. The algorithms have a polynomial complexity, whereas most of the solutions found in literature are NP-hard. (C) 2000 Elsevier Science B.V. All rights reserved.

关键词： real-time scheduling imprecise computation mandatory and optional subtasks error-cumulative periodic tasks task set transformation

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An adaptive scheduling for automobile control using imprecise computation and its experimental evaluation

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IEICE TRANSACTIONS ON COMMUNICATIONS 2001年第10期E84B卷 2749-2758页

作者： Inoue, S Nakanishi, F Kakuda, Y Toda, K Hiroshima City Univ Fac Informat Sci Hiroshima 7313194 Japan Informat Technol Res Inst Natl Inst Adv Ind Sci & Technol Tsukuba Ibaraki 3058568 Japan

The imprecise computation is one of the promising schemes in the real time systems to adapt quality of computations to change of load with keeping the deadlines of tasks in the systems. When overload occurs in the systems, the minimum requirements on the deadline are assured by decreasing quality of the computation. This paper describes how to apply the concept of the imprecise computation to automobile control in the expressway assuming the intelligent transportation system (shortly, ITS). The deadline violation of tasks for automobile control in the expressway induces collision of automobiles. Regardless of whether the expressway is congested or not, collision of automobiles must be avoided. To satisfy such requirement, the concept of the imprecise computation is effective. This paper proposes an adaptive scheduling using the imprecise computation to avoid collision of automobiles and increase throughput, and shows results of simulation experiments about an adaptive scheduling for automobiles control.

关键词： ITS imprecise computation real-time system automobile control scheduling

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Reward-based allocation of cluster and grid resources for imprecise computation model-based applications

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INTERNATIONAL JOURNAL OF WEB AND GRID SERVICES 2013年第2期9卷 146-171页

作者： Kim, Kyong Hoon Gyeongsang Natl Univ Dept Informat Jinju 660701 South Korea

Utility-based resource management is becoming an emerging issue as the utilisation of cluster resources in Grid computing is growing rapidly. In this paper, we provide a new imprecise computation (IC) application model for flexible reward-based Grid resource management. An application in the proposed model consists of multiple independent jobs, in which each job has two parts: mandatory part for the minimum quality and optional part for additional computations. This application model can be applied to QoS-related Grid applications and used in adaptive resource management. We also provide scheduling algorithms for resource allocation of the IC applications based on reward. The profitable optional execution time is analysed for both space-shared and time-shared scheduling policies. Simulation results show that the proposed schemes are beneficial to both users and resource providers in terms of application acceptance rate and total reward.

关键词： resource allocations cluster and grid scheduling imprecise computation reward-based scheduling scheduling analysis

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Practical imprecise computation Model: Theory and Practice 17

Practical Imprecise Computation Model: Theory and Practice

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17th IEEE International Symposium on Object/Component/Service-Oriented Real-Time Distributed Computing (ISORC)

作者： Chishiro, Hiroyuki Yamasaki, Nobuyuki Keio Univ Dept Informat & Comp Sci Yokohama Kanagawa 223 Japan

ISBN: (纸本)9781479944309

We introduce the research overview of the practical imprecise computation model to achieve imprecise real-time applications. The practical imprecise computation model has multiple mandatory parts as real-time parts and multiple optional parts as non-real-time parts. We explain a new concept of real-time scheduling in the practical imprecise computation model, called semi-fixed-priority scheduling. In addition, we explain a semi-fixed-priority scheduling algorithm, called Rate Monotonic with Wind-up Part (RMWP). RMWP schedules each part in the practical imprecise computation model in Rate Monotonic order. We also introduce a real-time operating system for semi-fixed-priority scheduling algorithms, called RT-Est. We describe programming paradigms for the practical imprecise computation model in RT-Est. RT-Est has the SIM architecture for simulating real-time scheduling algorithms and the visualization tool for drawing simulation results. Finally we give future research directions for the practical imprecise computation model in theory and practice.

关键词： computational modeling Measurement Programming Real-time systems Scheduling algorithms Upper bound imprecise computation Real-Time Scheduling Real-Time Systems Semi-Fixed-Priority Scheduling computational modeling real-time systems Scheduling algorithms time schedule Programming Upper bound

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Work-In-Progress: ARTIC: An Adaptive Real-Time imprecise computation Pipeline for Audio Analysis 40

Work-In-Progress: ARTIC: An Adaptive Real-Time Imprecise Com...

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40th IEEE Real-Time Systems Symposium (RTSS)

作者： Yantosca, Michael Cheng, Albert M. K. Univ Houston Dept Comp Sci Real Time Syst Lab Houston TX 77004 USA FlightAware Houston TX 77046 USA

ISBN: (纸本)9781728144030

One of the more complex issues facing natural language processing (NLP) is how to deal with overlapped speech, i.e., when two or more speakers interfere with or talk over each other, and the more general case of co-channel speech, i.e., when two or more speakers are present in an audio stream regardless of interference. Frequently, one speaker is selected as a primary speaker for the purpose of analysis with other speakers relegated to the category of interfering speakers. Despite the breadth of research into overlapped speech detection, few endeavors have been made into preserving the speech of socalled interfering speakers. A compelling case can be made for a more comprehensive analysis of co-channel speech in the fields of computational linguistics, accessibility automation, and entertainment, particularly under real-time constraints. Currently available open-source audio libraries, while technically capable of supporting such research endeavors, are cumbersome to work with. To this end, the work introduces the Adaptive Real-Time imprecise computation (ARTIC) pipeline for audio analysis, a simple but flexible approach to stream processing that tracks computation times and deadlines for the various pipeline stages and affords the user the ability to specify automatic precision reductions to avoid projected deadline misses as well as automatic precision increases to combat underutilization. A proof of concept is tested with the intent to build upon this groundwork for a more comprehensive project having the goal of multi-speaker interference detection and eventually speaker separation.

关键词： real-time speech analysis filtering speaker interference detection imprecise computation NLP source separation

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imprecise computation technique to schedule AND/OR tasks with global end-to-end deadline in distributed real-time systems

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AEJ - Alexandria Engineering Journal 2003年第5期42卷 577-587页

作者： El-Haweet, Wafaa A. El-Meligy, Hanan H. Abd, El-Salam, Ibrahim Comp. Sci. and Automat. Cntr. Dept. Alexandria University Alexandria Egypt

In a real-time system, tasks must produce logically correct results by their deadlines. These tasks usually don't need to be executed in a sequential order. Rather, certain precedence constraints must be handled between them along with timing constraints to provide correct scheduling and consequently correct execution. In traditional precedence-constrained scheduling, a task is ready to execute when all of its direct predecessors are completed. Such task is called an AND task. In many applications, some tasks are ready to execute when one or more but not necessarily all of their direct predecessors are completed. These tasks are called OR tasks. The resultant system containing both AND and OR tasks is said to have AND/OR precedence constraints. Directed Acyclic Graphs DAGs are used to represent these systems. This paper introduces a method to combine both precedence constraints and timing constraints into the same scheduling problem. Timing constraints here are in the form of a global End-to-End Deadline EED between a start task and an end task of the AND/OR graph representing the task system. A proposed imprecise computation Technique ICT is introduced to maximize the solution quality within the available time. ICT is motivated by the fact that one can trade off precision with timeliness;it prevents the total processing time of the system from stretching over the EED. To examine and evaluate this proposed imprecise scheduling solution, a Random Graph Generator algorithm RGG is created to provide a wide range of random DAGs to be used in the simulation experiments.

关键词： AND/OR precedence constraints Dependability Design-to-time real-time scheduling Directed acyclic graphs imprecise computation

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A Speculative Concurrency Control in Real-Time Spatial Big Data Using Real-Time Nested Spatial Transactions and imprecise computation 14

A Speculative Concurrency Control in Real-Time Spatial Big D...

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14th IEEE/ACS International Conference on Computer Systems and Applications (AICCSA)

作者： Hamdi, Sana Bouazizi, Emna Faiz, Sami Univ Carthage Tunisia Polytech Sch BP 2078 La Marsa Tunisia Sfax Univ MIRACL Lab BP 1088 Sfax 3018 Tunisia LTSIRS Lab BP 37 Tunis 1002 Tunisia

ISBN: (纸本)9781538635810

Real-time spatial applications have become more and more important. These applications are innovating in the way we live. As a result, there is a huge amount of real-time spatial data generated everyday, accessed simultaneously by two types of transactions, Update transactions and User transactions (continuous requests). In real-time spatial Big Data, the performance can be increased by allowing concurrent execution of transactions. This activity is called concurrency control. The concurrency control algorithm must be used to ensure serializability of transaction scheduling and to maintain data consistency. Several works have been done in this area, but without holding into account the existence of a huge volume of data. In this paper, we apply the technique of imprecise computation for real-time spatial nested transactions. We consider that imprecise transaction consist that a User transaction is decomposed logically into a one mandatory sub-transaction and one or more optional sub-transactions and an Update transaction consists only of a single mandatory sub-transaction. We propose an improvement of an existing Two-Shadow Speculative Concurrency Control (SCC-2S) with priority with the use of the imprecise real-time spatial transaction. Our main objectives are: to guarantee the data freshness, to enhance the deadline miss ratio even in the presence of conflicts and unpredictable workloads and finally to satisfy the requirements of users by the improving of the quality of service (QoS).

关键词： Real-Time Spatial Big Data User Transaction Update Transaction Nested Transaction Speculative Concurrency Control imprecise computation Quality of Service

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