There are many problems in industrial process control systems due to a long system response delay, dead-zone and/or saturation of the actuator mechanisms, uncertainties in the system model and/or parameters, and proce...
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There are many problems in industrial process control systems due to a long system response delay, dead-zone and/or saturation of the actuator mechanisms, uncertainties in the system model and/or parameters, and process noise. To overcome these problems, an adaptive controller is designed using neural networks and tested extensively via simulations. One of the key problems in designing such a controller is to develop an efficient training algorithm. Neural networks are usually trained using the output errors of the network, instead of using the output errors of the controlled plant. However, when a neural network is used to control a plant directly, the output errors of the network are unknown, since the desired control actions are unknown. In this paper, we propose a simple training algorithm for a class of nonlinear systems, which enables the neural network to be trained by the output errors of the controlled plant. The only a priori knowledge of the controlled plant is the direction of its output response. A detailed analysis of the algorithm is presented and the corresponding theorems are proved. Due to its simple structure and algorithm, and good performance, the proposed controller has high potential for handling difficult problems in industrial process control systems.
Synchronization algorithm is proposed which uses one of two probabilistic techniques to estimate remote clock values, and uses an interactive convergence algorithm on the resulting estimates to adjust the local clock....
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Synchronization algorithm is proposed which uses one of two probabilistic techniques to estimate remote clock values, and uses an interactive convergence algorithm on the resulting estimates to adjust the local clock. The algorithm does not require master/slave clocks and reduces the number of messages needed. As a result it is suitable for use in large distributed systems.< >
A new hierarchical collision avoidance scheme is proposed to coordinate multiple robots in a common workspace by combining the techniques of intelligent control and neural networks (NNs). The high level in the hierarc...
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A new hierarchical collision avoidance scheme is proposed to coordinate multiple robots in a common workspace by combining the techniques of intelligent control and neural networks (NNs). The high level in the hierarchy is formed by a knowledge-based coordinator (KBC) and an NN-based predictor, and the low level consists of the robots to be coordinated. The authors state the problem of coordinating multiple robots for collision avoidance and the basic principles of the KBC. The knowledge acquisition and representation of collision detection and avoidance for both cylindrical- and revolute-type robots are discussed. Design of the NN-based predictor and the KBC is summarized. The proposed scheme was tested extensively via simulations for both types of robots, showing promising performance.< >
The authors propose a new loading sharing (LS) algorithm for real-time applications that accounts for the effect of future task arrivals on locating the best receiver for each unguaranteed task. The LS algorithm minim...
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The authors propose a new loading sharing (LS) algorithm for real-time applications that accounts for the effect of future task arrivals on locating the best receiver for each unguaranteed task. The LS algorithm minimizes not only the probability of transferring an unguaranteed task T to an incapable node with Bayesian analysis, but also the probability that a remote node fails to guarantee T because of future arrivals of higher-laxity tasks with queuing analysis. All parameters needed for a node's LS decision are collected/estimated online using time-stamped region-change broadcasts and Bayesian estimation. Simulation results show that the proposed LS algorithm outperforms other existing algorithms in minimizing the probability of dynamic failure, task collisions, and excessive task transfers. The performance improvement becomes more pronounced as the degree of system heterogeneity increases.< >
An analytical model for the performance evaluation of asynchronous hypercubes is presented. This analysis is aimed at modeling a deadlock-free wormhole routing scheme prevalent on second-generation hypercube systems. ...
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An analytical model for the performance evaluation of asynchronous hypercubes is presented. This analysis is aimed at modeling a deadlock-free wormhole routing scheme prevalent on second-generation hypercube systems. Probability of blocking and average message delay are discussed. The communication traffic to find the probability of blocking is the starting point. The traffic analysis can capture any message destination distribution. The average message delay that consists of two parts is found. The analysis is extended to virtual cut-through routing and random wormhole routing techniques. The validity of the model is demonstrated.< >
A generalized version of the well known periodic Riccati differential equation, which arises in certain optimal filtering problems for linear periodic systems, is studied. A monotonicity property for symmetry periodic...
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A generalized version of the well known periodic Riccati differential equation, which arises in certain optimal filtering problems for linear periodic systems, is studied. A monotonicity property for symmetry periodic equilibrium solutions and the existence of a maximal symmetric periodic equilibrium solution are established.< >
The authors present a parallel algorithm for logic simulation of VLSI circuits. It is implemented on a network of transputers connected in a ring topology. The approach is based on partitioning a functionality matrix ...
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The authors present a parallel algorithm for logic simulation of VLSI circuits. It is implemented on a network of transputers connected in a ring topology. The approach is based on partitioning a functionality matrix representation of the circuit among the transputers and adopting a data flow technique for the solution. A significant aspect of the algorithm is that it overlaps computation with communication, thereby reducing the communication overhead. It also attempts even distribution of load in order to reduce processor idle time. The algorithm possesses the advantages of ease of implementation and ease of extension to incorporate additional parameters for simulation. Performance results of the algorithm are given.< >
With ever-increasing reliance on digital computers in embedded systems such as in space, avionics, manufacturing, and life-support monitoring/control applications, the need for dependable systems that deliver services...
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With ever-increasing reliance on digital computers in embedded systems such as in space, avionics, manufacturing, and life-support monitoring/control applications, the need for dependable systems that deliver services in a timely manner has become crucial. Embedded systems often interact with the external environment and operate under strict timeliness and reliability requirements. Fault tolerance and real-time requirements on a system often influence one another in subtle ways, for example, the requirements on a highly—available system, such as an air traffic control system, may derive the timing constraints imposed on certain critical tasks. In cases where a set of interacting tasks operate under strict timing constraints, missing a deadline may result in a catastrophic system failure, which was termed a dynamic failure in (Shin, Krishna, and Lee, 1985). This paper argues that fault- tolerance and real-time requirements are not orthogonal and it addresses some of the challenges that confront the designers of fault-tolerant real-time systems. These challenges include formal specification of reliability and timing requirements, appropriate language and operating system support for providing fault-tolerance in a time-critical system, new scheduling theories which consider multiple resources and fault-tolerance, tradeoff between time and space redundancy, and predictable redundancy management in the presence of faults.
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