Electrical and Electronic Engineering publications
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Item Metadata only Considerations in setting up supporting facilities for microprocessor applications work and teaching(Institute of Engineering and Technology, 1982) Pucknell, D.A.; Liebelt, M.J.; Raymond, M.L.J.; Wotton, N.It is possible to identify various levels of sophistication at which microprocessor/microcomputer applications can take place, and for which supporting facilities are needed. It can also be argued that effective teaching in the microprocessor area must be on a largely 'hands-on' basis, and that application and teaching equipment needs are therefore substantially the same. The paper identifies the levels and suggests facilities in both hardware and software which are needed to support work at each level. The paper goes on to discuss particular facilities which have been developed to meet these needs. It will be seen that support at lower levels can be readily provided at modest cost and can form part of higher level support if and when it is needed, so that the complete facilities can be realised in an effective but economical manner. Typical costs at each level of support are given as a guide.Item Metadata only Autopilot for ship control, Pt. 2: Simulation studies(IET, 1983) Lim, C.C.; Forsythe, W.In part 1 of the paper a self-tuning ship-autopilot design was presented that reconciles the conflicting demands of course keeping and of manoeuvring by using two modes of operation. During the course-keeping mode the performance criterion is formulated to minimise heading error, propulsion losses and rudder activity, while in the manoeuvring phase the concern is simply to minimise heading error. The system parameters are identified using recursive least-squares estimation to confer on the autopilot a high degree of adaptability, as illustrated in the simulation studies in this paper.Item Metadata only Autopilot for ship control, Pt 1: Theoretical design(IET, 1983) Lim, C.C.; Forsythe, W.A self-tuning ship-autopilot design is presented that reconciles the conflicting demands of course keeping and of manoeuvring by using two modes of operation. During the course-keeping mode the performance criterion is formulated to minimise heading error, propulsion losses and rudder activity, while in the manoeuvring phase the concern is simply to minimise heading error. The system parameters are identified using recursive least-squares estimation to confer on the autopilot a high degree of adaptability, as illustrated in the simulation studies of part 2 of the paper.Item Metadata only General pole restriction controller design(Taylor & Francis, 1988) Lim, C.C.; Teo, K.L.; Hang, C.C.Pole-assignment controller design suffers from the disadvantage that the prescribed pole locations may not be a suitable choice when the dynamics of the process are changing. A general design method that restricts the closed-loop poles to be within a certain desired region specified by engineering judgement, instead of fixing the poles in a prescribed location, is presented. The method can be used for regulating a process with time delay, non-minimum zero-phase behaviour, and open-loop unstable characteristics.Item Metadata only Time optimal control computation with application to ship steering(Plenum Publishing, 1988) Teo, K.L.; Lim, C.C.An efficient computational scheme for solving a general class of linear time optimal control problems, where the target set is a compact and convex set with nonempty interior in the state space, is presented. The scheme is applied to solve the ship steering control problem, and excellent results are obtained.Item Metadata only A stochastic optimal control approach to a mathematical drug administration model(Maxwell Pergamon Macmillan, 1989) Lim, C.C.; Teo, K.L.In this paper, a mathematical model is derived for an optimal control problem involving drug administration policy. The problem is stochastic in nature as there are uncertainties in both the drug effectiveness and initial physiological state. Furthermore, to avoid the undesirable side effects, the maximum allowable instantaneous and accumulative limits of the dosage must also be taken into account. The aim is to show that the resulting stochastic optimal control problem is equivalent to a deterministic optimal control problem and hence solvable by a recent optimal control software MISER. Numerical examples are included for illustration. © 1989.Item Metadata only Mean-square stability of stochastic differential time-lag systems(Taylor & Francis, 1989) Lim, C.C.; Teo, K.L.Two sets of sufficient conditions for the mean-square asymptotic stability of the equilibrium state of linear differential time-lag systems with non-stationary random coefficients are derived. Each of the sets of sufficient conditions is then shown to be equivalent to a corresponding unconstrained optimization problem. Hence, it can readily be solved by standard efficient optimization techniques. The usual trial-and-error method of finding the required parameters to satisfy the stability conditions can now be avoided.Item Metadata only A computational method for a class of dynamical optimization problems in which the terminal time is conditionally free(Oxford University Press, 1989) Teo, K.L.; Goh, C.J.; Lim, C.C.In this paper, we consider a class of dynamical optimization problems in which the terminal time is determined by a stopping criterion. The dynamical system is described by a system of ordinary differential equations, and the cost functional is to be minimized with respect to the control together with the initial vector. A computational method based on the concept of control parametrization is developed for solving this class of dynamical optimization problems. For illustration, an aeronautical control problem is solved using the proposed method. © 1989 Oxford University Press.Item Metadata only Optimal insulin infusion control via a mathematical blood glucoregulatory model with fuzzy parameters(Hemisphere Publishing, 1991) Lim, C.C.; Teo, K.L.In this paper, we consider a blood glucose-insulin model subject to parameter variation. Our aim is to use a mathematical optimization technique lo derive insulin infusion programs for the regulation of the blood glucose level in the case of worst possible parameter values. Numerical computation and simulation studies are carried out to verify the performance of the method on regulation of initially high blood glucose level while fasting and of blood glucose level after a meal prior to which blood glucose is at its rest level.Item Metadata only Photovoltaic gate biasing edge effect in GaAs MESFETs(IEEE, 1991) Abbott, D.; Cui, S.; Eshraghian, K.; McCabe, E.A new effect in planar GaAs MESFETs, whereby a sharp increase in optical gain at the transistor edges occurs, is reported for the first time. This gain effect only appears when a large resistor is inserted in series with the gate, to produce the conditions for photovoltaic gate biasing. The mechanism for increased gain at the edges is suggested to be due to carrier photogeneration in the substrate that is subsequently collected by the gate. Application in the area of X-Y addressable transistor array imagers is proposed.Item Metadata only Performance analysis of dynamic multitasking imprecise computation system(IET, 1991) Lim, C.C.; Zhao, W.The scheduling of tasks in dynamic multitasking computer systems using imprecise partial computations is studied. In this system, tasks arrive randomly during run-time, and they are to be processed as quickly as possible. The task is modelled in such a way that each task has two parts of computation: a mandatory part, and an optional part. The tasks are scheduled such that: if the total number of tasks in the system is no more than M (a system parameter), the tasks are executed fully to produce precise results. When the total number of tasks exceeds M, then only the mandatory parts of the tasks are executed. To study this dynamic imprecise computation system, the authors propose three performance metrics to measure responsiveness and quality of computation of tasks. Queueing methods are used to analyse the scheduling problem, and performance metrics are computed numerically. The performance of the scheme is assessed, and found to be effective in keeping the mean task waiting time at a low value when the system is heavily loaded or overloaded.Item Metadata only Performance of token ring protocols for real-time message transmission(IEEE, 1994) YAO, L.J.; ZHAO, W.; LIM, C.C.; Global Telecommunications Conference, 1994 (28 Nov 1994 - 2 Dec 1994 : San Francisco, CA)We study the average case performance of three token ring protocols through simulation. The first is the token passing protocol which does not adhere to the EDF policy but has a minimal overhead. The second is a modified priority-driven protocol which only approximates the EDF policy with a moderate overhead. The third is the window protocol which implements the exact EDF policy, but its contention overhead might be potentially high. It is found that under the current network technology, the window protocol achieves the best performance in supporting urgent real-time messages. We have also noted that when the ring gets faster, the difference in the performance of the three protocols is reduced. Therefore, the average case performance of a real-time protocol is determined by both the transmission policy employed and the contention overhead incurredItem Metadata only An enhanced neural adaptive control scheme for discrete-time non-affine nonlinear systems(Centre of Intelligent Information Processing Systems, 1995) Mazumdar, S.K.; Lim, C.C.An adaptive control procedure utilising neural networks is presented. The method is based on the model reference control technique and can be applied to multi-input multi-output discrete-time nonlinear systems of unknown structure.Multi-layered neural networks are used to approximate the plant Jacobian and synthesise the controller. An enhanced reference model is proposed that generates the desired output response and enables sufficient conditions for the convergence of the tracking error between the desired output and controlled output to be derived. Lyapunov theory is used to show that the overall system is stable. Simulation studies demonstrate that the proposed scheme performs well even in the presence of dynamic perftubations.Item Metadata only A comparative study of three token ring protocols for real time communications(International Society for Mini and Microcomputers, 1995) Yao, L.; Zhao, W.; Lim, C. C.Item Metadata only Translation invariant pattern recognition: A real-time neural network architecture based on biological visual spatial attention(Centre of Intelligent Information Processing Systems, 1995) Lozo, Peter; Lim, C. C.; Nandagopal, D.Item Metadata only Electromagnetic design aspects of packages for monolithic microwave integrated circuit based arrays with integrated antenna elements(Institute of Electrical and Electronic Engineers, 1995) Griffin, D. W.; Parfitt, Andrew JamesItem Metadata only Personal communications services (PCS) - An overview(Telecommunication Society of Australia, 1995) Coutts, R.Item Metadata only Fuzzy motion estimation(Centre of Intelligent Information Processing Systems, 1995) Kouzani, Abbas Z.; Bouzerdoum, A.; Liebelt, Michael J.Item Metadata only An editorial: Mobile Communications(Institute of Electrical and Electronics Engineers, 1995) Coutts, R.; Thomas, B.Item Metadata only A conventional power system stabiliser with an auxiliary self-tuning/fixed parameter controller(Butterworth Heineman, 1995) Wen, C.; Gibbard, Michael J.