Abstract
The so-called screening solitons that occur in steady state when an external bias voltage is appropriately applied to a PR crystal are known to occur when the drift term dominates in the expression of the space charge field. In a recent study, the effects arising from first-order diffusion terms have also been investigated. It was found that the PR soliton can experience adiabatically self-deflection that varies linearly with the applied electric field. However, recent experiments suggest that this self-deflection can exceed that predicted by theory, especially in the regime of quite high bias fields. To account for this discrepancy, this paper investigates the effects of other higher-order electric field terms on the evolution of bright steady-state solitons in PR media.

Abstract
Supply current test is well established for digital CMOS circuits and the advantages of improved observability and reliability indication have prompted its use for analogue and mixed signal circuits. A short review of the literature on this subject is given. Fault simulation is used for the investigation of dynamic supply current test of a PLL, confirming existing results from smaller circuits that a combination of supply current and output voltage monitoring leads to higher fault coverage. In the paper, fault coverage is further improved, using crosscorrelation of the supply current and output signals, and the potential for BIST implementation of this technique is demonstrated using low resolution polarised crosscorrelation. Fault simulation is also performed on an analogue multiplier to investigate the effect of process parameter deviations on the supply current. The fault coverage is found to be improved by removing the DC component of the signal. Encouraging results are obtained from the application of supply current test techniques to a commercial mixed signal ASIC currently beyond the capabilities of analogue fault simulation, indicating that efforts at improving fault simulation in this area are worthwhile. The requirements for fault modelling and simulation to support supply current test are discussed and some initial results of accelerating this process using macromodelling are presented.

Abstract
It is shown that a new type of incoherently coupled soliton pairs is possible under steady-state conditions provided that their carrier beams share the same polarization and wavelength and are mutually incoherent. They can be readily realized in a simple experimental setup where the optical beams co-propagate collinearly in a biased photorefractive crystal, in which case they experience equal electro-optic coefficients. The two optical beams can be also slightly misaligned at the input so as to differentiate them at the output plane.

Abstract
This paper presents a conceptual architecture for the control of multiple autonomous underwater vehicles based on the concept of Generalized Vehicle. The design of this architecture was driven by requirements extracted from the analysis of operational scenarios involving the operation of multiple vehicles and embodies an extension of the Dynamically Reconfigurable Control Architecture for an AUV proposed by the authors in previous published work.

Abstract
Classes of oceanographic missions addressing relevant distinct scientific and applied objectives in the Portuguese coastal waters are examined in the context of an R&D project aiming at providing a methodological framework adapted to the specific requirements of AUV-based systems design. Preliminary results consisting on the mapping of requirements onto a modular system are presented.

Abstract
An investigation is performed on the characteristics of the self-referencing resonant fiber optic intensity based sensor supported by a Mach-Zehnder topology. Both transmissive and reflective configurations are analyzed. Via the definition of the measurement parameter (R parameter) the linearity and sensitivity of the sensor are addressed. Theoretical and experimental results are compared. The problem of sensor design is under consideration. (C) 1996 American Institute of Physics.