Spacecraft attitude control is conventionally achieved by the use of reaction wheel or thruster based control schemes. The authors investigate the use of a neural network controller for a thruster based spacecraft att...
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Spacecraft attitude control is conventionally achieved by the use of reaction wheel or thruster based control schemes. The authors investigate the use of a neural network controller for a thruster based spacecraft attitude control system. They propose to train the neural network using a genetic algorithm.< >
Recent advances in information set decoding techniques for cyclic block codes have made it possible to combine the well-known error trapping decoding technique with an information set decoding technique which splits t...
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Recent advances in information set decoding techniques for cyclic block codes have made it possible to combine the well-known error trapping decoding technique with an information set decoding technique which splits the received word into two or more sections. The result is a combined splitting and error trapping soft-decision algorithm which has better performance and/or lower complexity than the most effective existing algorithms (i.e. the Chase (1972) and Wolf algorithms). This makes the algorithm a strong candidate for applications where the advantage of high performance block codes are of interest, such as in packet radio and mobile radio systems. The new combined algorithm is ideally suited for DSP implementation.< >
With the increased bandwidth capabilities offered by fibre optic transmission, the loss of a single fibre-optic cable can affect a vast number of voice circuits. Protection against failure has been an important aspect...
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With the increased bandwidth capabilities offered by fibre optic transmission, the loss of a single fibre-optic cable can affect a vast number of voice circuits. Protection against failure has been an important aspect of most modern transmission systems. There are two approaches towards the survivability of an optical network: the conventional approach which is based on 1:1 protection switching using diverse routes; or the new approach which is based on the rapid reconfiguration of a high-speed digital cross-connect system (DCS). The authors examine the restoration strategy based on DCS reconfiguration, which has a higher potential to provide a high degree of protection and flexibility at lower cost. Five distributed restoration algorithms are examined and compared. A multi-layer real-time restoration algorithm is presented as an effective solution to achieve extremely fast network failure restoration.< >
The heating input into domestic buildings in total is of importance in the energy requirements of the country. Although the standard domiciliary unit is far too small to justify an air-conditioning system, the regulat...
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The heating input into domestic buildings in total is of importance in the energy requirements of the country. Although the standard domiciliary unit is far too small to justify an air-conditioning system, the regulation of the heated space is subject to a myriad of random disturbances which often result in poor performance manifesting itself as occupant discomfort. That the conventional thermostat control can be bettered is not in question. The issue is whether such improvement in control can be carried out inexpensively enough to justify the capital expenditure for a residential unit. The performance criterion of the system as a whole does not offer many possibilities for energy conservation and increased efficiency. However, by the use of an intelligent supervisor on the control it is hoped to provide cost benefits as well as improved performance in the field of user 'comfort'. Fuzzy logic is used as the tool for implementing the controlalgorithms. The nature of the plant to be controlled justifies the choice of fuzzy logic as will be seen from the description of the plant and the disturbances affecting it.< >
Vector control offers the possibility of servo motor performance from robust induction motors, but at the cost of increasing the complexity of the controller. A typical drive system comprises a motor, an inverter and ...
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Vector control offers the possibility of servo motor performance from robust induction motors, but at the cost of increasing the complexity of the controller. A typical drive system comprises a motor, an inverter and a controller. To limit costs it is necessary to reach a compromise between the performance of each component. Typically the cost of the motor is determined by the intended load and by the operating environment, but there is more flexibility in choice and design of the inverter and the controller. Some of the implementation details that must be traded off include the sampling rate of a digital controller, the sophistication of the controlalgorithms, the resolution of analogue to digital interfaces and the switching frequency of the inverter. By modelling the entire drive system on a computer, the 'best' compromise can be established. To do this requires an easy and meaningful measure of drive performance. Most of the literature presents graphs of shaft speed and current and voltage waveforms for a speed step or reversal. These results apply to specific load conditions and are difficult to compare.< >
The incorporation of a traditional tripartite genetic algorithm into an engineering decision support system is discussed. In particular, the issues of achieving a reliable and accurate solution are addressed. The gene...
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The incorporation of a traditional tripartite genetic algorithm into an engineering decision support system is discussed. In particular, the issues of achieving a reliable and accurate solution are addressed. The general design of the genetic algorithm used for this work is shown. The usual three functions of seeded selection, cross-over and mutation are applied. A fourth genetic operator, inversion, is also applied. The decision support system advises in the domain of strategic sludge disposal. The aim for the genetic algorithm is to find the optimum selection of farms where sewage sludge can be disposed of, out of all of the farms available in a region.< >
Cooperating arm configurations include isolated robotic cells, robots with overlapping workspaces and also robots working on a cooperative manipulation task. All require detailed planning for coordination but the latt...
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Cooperating arm configurations include isolated robotic cells, robots with overlapping workspaces and also robots working on a cooperative manipulation task. All require detailed planning for coordination but the latter configuration is particularly intensive in processing and planning requirements. The paper provides an overview of the multi-manipulator research at the Queen's University and highlights the significance of concurrent processing and parallel algorithms in a number of key areas. These range from high level collision avoidance strategies and optimisation of limb movements down to individual joint control.< >
The principle methods in finding good solutions to discrete optimisation problems are discussed. geneticalgorithms (GAs) are methods which start with a population of trial solutions, and by processes which mimic thos...
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The principle methods in finding good solutions to discrete optimisation problems are discussed. geneticalgorithms (GAs) are methods which start with a population of trial solutions, and by processes which mimic those found in evolution and natural selection, the population is improved from generation to generation until a population is arrived at containing one or more good solutions. When a good solution spontaneously arises in one individual, then this tends to move the entire population of solutions towards that region of the solution space. Thus, when the solutions migrate to the region of the global optimum, the coverage of the solution space is more complete and there is less likelihood of becoming stuck in a local minimum. It is this feature that makes GAs of such interest, and therefore the subject of this paper. The aim of this paper is to give a brief description of the algorithm, followed by some implementation considerations. Then, some existing and possible applications to digital signal processing, circuit design and related topics are presented, together with possible research directions.< >
The authors present DSP-based instrumentation for real-time measurement and control of high frequency jet ventilation in the area of critical care medicine. The system has been initially developed to test the hypothes...
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The authors present DSP-based instrumentation for real-time measurement and control of high frequency jet ventilation in the area of critical care medicine. The system has been initially developed to test the hypothesis that acoustic resonance of the respiratory airways represents an optimal state for alveolar gas exchange. Real-time signal processing algorithms have been implemented around a user-friendly system to aid in the identification of transfer function relationships between respiratory data. This analysis is the first step towards developing an automatically controlled, self-tuning high frequency jet ventilator.< >
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