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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.

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.

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.

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.

When developing distributed scheduling algorithms such as communication protocols, issues in achieving optimal policy and minimizing overhead must be addressed. This problem is examined in the context of a specific distributed system-the token ring communication network. Three token ring protocols are considered which are representative of many existing ones in the sense that they incorporate message time constraints at different levels and implement the earliest deadline first transmission (scheduling) policy at different degrees with different overheads. Through a worst-case analysis, the performance of these three token ring protocols is compared. It is concluded that to evaluate a distributed scheduling algorithm such as a communication protocol, it is necessary to not only consider the scheduling policy employed but also to take into account the overhead incurred due to the implementation of the scheduling policy. >

This paper presents novel closed-form solutions to the sub-channel and power allocation problems of an orthogonal frequency division multiple access (OFDMA) system. We model the Rayleigh fading channel as a finite-state Markov channel (FSMC) by partitioning the received signal-to-noise ratio (SNR) into several intervals. We use the sub-band formation and lumpability to reduce the size of channel state information (CSI) and to reliably predict the CSI with the corresponding state transition and steady-state probabilities. Simulation results show that the limited feedback scheme due to lumpable FSMC is not only experiencing less prediction error than the typical full feedback scheme but also achieving near-optimum capacity.

This paper presents an application of our previously introduced (Lozo, 1996) real-time neural circuit feedforward excitation-feedback presynaptic facilitation (FFE-FBPF) to object recognition in complex and cluttered TV images.

The design and implementation of a double precision floating-point IEEE-754 standard adder is described which uses "flagged prefix addition" to merge rounding with the significand addition. The floating-point adder is implemented in 0.5 /spl mu/m CMOS, measures 1.8 mm/sup 2/, has a 3-cycle latency and implements all rounding modes. A modified version of this floating-point adder can perform accumulation in 2-cycles with a small amount of extra hardware for use in a parallel processor node. This is achieved by feeding back the previous un-normalised but correctly rounded result together with the normalisation distance. A 2-cycle latency floating-point adder architecture with potentially the same cycle time that also employs flagged prefix addition is described. It also incorporates a fast prediction scheme for the true subtraction of significands with an exponent difference of 1, with one less adder.

In this paper, Rayleigh fading channel with an OFDMA system is modeled as a finite-state Markov channel (FSMC) by partitioning the received signal envelope into several intervals. With the aid of sub-band formation and property of lumpability, the size of feedback information can be reduced. This approach involves reducing an exponentially increased states of Markov channel to multiple lumpable Markov channels. The corresponding state transition probabilities and steady-state probabilities are used to predict channel states information in multiple symbol durations ahead. Some simulation examples are presented to illustrate the capability of the lumpable FSMC in channel prediction.

The scheduling of tasks in dynamic multitasking computer systems using imprecise (partial) computations is studied. In our system, tasks arrive randomly during run-time, and they are to be processed as quickly as possible. We model the task 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, i.e. both the mandatory and the optional parts are executed. When the total number of tasks exceeds M, then only the mandatory parts of the tasks are executed. As less computation resourse is used on each task under this imprecise computation condi- tion, the response time of tasks should improve significantly. To study this dynamic imprecise computation system, we propose three per- formance 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. The effect of variations in parameter values on the system performance is also examined.

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.