Abstract
This paper describes the specification and design of a prototype of a low cost open system for the inspection of underwater structures based on a remotely operated underwater vehicle under the project IES, a 3 year long effort funded by the Portuguese R&D program Praxis XXI. Unlike commercial approaches, a modular open system characterised by the incorporation of an on-board computer allowing for advanced control capabilities is envisaged. The control console is based on a standard PC and the tether is used only for power delivery and to establish a simple communication channel. In this project, we use advanced hybrid control techniques for sophisticated semi-autonomous operation management and control. The control architecture reuses part of the one designed for the underwater vehicle Isurus operated by the Laboratory of Underwater Systems and Technologies of Porto University. The implementation is designed in order to allow for multiple sensor configurations specified as add-ins. This leads to a dynamic, scalable and flexible system that can be easily configured according to the user specifications.

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Abstract
This paper describes the mission control software used in the LSTS/FEUP underwater vehicles. This software follows the guidelines of the generalized vehicle architecture [1], adapts the original idea to encompass the current application requirements and constitutes a first implementation. The work is focused on the design and implementation of an application that can be easily adapted to different vehicle configurations or even to different vehicles. One of the desired goals was to enhance software reusability and to establish a development environment that allows developers with a minimal knowledge of coding details to upgrade the application. To assist this purpose, a CASE tool, which provides modern software development techniques, was used. A simulation environment was also developed whose purpose is to test the applications and to detect possible malfunctions before they occur during mission execution.

Abstract
A procedure for parameter estimation of multicomponent Polynomial Phase Signals is presented. This scheme, while restricted to high SNR's, has the advantage of being extremely simple. It is also insensitive to the equal-coefficient identifiability problem of HAF (High-order Ambiguity Function) based methods. It poses, however, some restrictions on the component amplitudes. Its performance in noise is investigated, and confirmed with several examples.

Abstract
The failure of the traditional definition of instantaneous frequency (IFt) in the multicomponent case has been often reported, We will determine the reasons for failure of this definition, That will enable us to understand and integrate all previously reported cases in a simple unified theory. As a direct consequence, we will be able to extrapolate and predict the behavior of the traditional definition for any type of multicomponent signal.

Abstract