Abstract
In this paper we present two subspace identification methods implemented through sequences of modified Householder algorithm. The main idea was to show that subspace identification methods can be represented as sequences of least squares problems and implemented wing QR factorizations. Therefore, it is possible to develop iterative algorithms with most of the advantages of this kind of methods, and still improve the numerical efficiency, in order to deal with real-tme applications and minimize the computational burden.

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Abstract

Abstract
The in-situ investigation and characterization of ISC'2 experimental site comprised the application of several geophysical borehole, penetration and surface methods, namely S waves high resolution shallow reflection (SHRR), ground penetrating radar (GPR), P and S waves seismic cross-hole (CH), downhole (DII), refraction, electrical resistivity, as well as geotechnical tests, namely SPT, CPT, DMT, among others. The site, located within the campus of Faculty of Engineering of the University of Porto (FEUP), is geologically fortned by an upper layer of heterogeneous residual granite soil overlaying rather weathered granite contacting a gneissic migmatite. Direct and indirect results from some of the referred surveys are compared between them and with some of the available geological and geotechnical information, in particular hereby (Part II), those obtained from SHRR, GPR, and CH seismic tests. The integration of the available information was then used to build a tentative geological interpretation model. One of the objectives of this component of the global study, hereby presented, was to evaluate the possibility of obtaining valid infortnation from a single technique, particularly, S waves shallow reflection.

Abstract
In this paper we describe an algorithm that produces a post mission estimate of the spatial evolution of the Isurus AUV. To make this post processing possible, the navigation system records on the vehicle logging system all the navigation data received during the mission execution. The data comprise the depth of the vehicle, the outputs of the tilt sensors and digital compass, the angular velocity of the propeller, as well as acoustic range measurements to a set of transponders. After mission completion, the logged data is then processed to produce the estimate of the evolution of the vehicle. The algorithm used to process this data is based on a fixed interval nonlinear stochastic smoothing scheme and produces an estimate that evolves continuously in time. For each instant of time, the post mission position estimate is based on all the information collected during the mission, as opposed to real time estimates that can only take into account past data.

Abstract
The latest technological developments on electronics, mechanics, optics, and other areas have made possible the availability of low cost and high performance sensors for navigation. This opens doors to the development of high accuracy navigation systems to be used on low cost small size underwater vehicles. This paper describes th development and implementation of the navigation system for the remotely operated vehicle (ROV) of the IES Project.