Abstract
A technique for interrogating multiplexed FBG sensors using all-fiber low-cost devices is demonstrated. It is based on spectral filtering employing a fused biconical wavelength-division multiplexer and on amplitude-to-phase optical conversion to perform power referencing. Four FBG sensors are wavelength multiplexed in the network, and a 3-nm-wide tunable optical filter is, employed at the detection block for sensor demultiplexing. With this technique an operation range of more than 2 nm is demonstrated for the sensors with achievable wavelength static resolution ranging from 1.9 to 13.4 pm/Hz(1/2) with no observable hysteresis. As for power referencing, the system is proven to be unaffected by power variations as high as 75% of the total power launched by the source. Finally, output-phase variations due to crosstalk are shown to be under 1% of-the total output phase range, with more than 29-dB optical isolation between channels.

Abstract
Sliding mode controllers are derived for the control of the average output voltage in DC/DC power converters. The controller design is carried out on the basis of well-known bilinear models of such circuits. A cascaded control structure is chosen for ease of control realization and to exploit the motion separation property of this power converter. The performance of the proposed sliding mode controllers is tested for the buck and boost converter type. The numerical simulations will demonstrate the efficiency of sliding mode techniques in this field as a powerful alternative to other existing methods. © 2003 IFAC.

Abstract
Bragg gratings written in high-birefringence fibre optics are a key element in the simultaneous measurement of transversal strain components and temperature, and they have several applications as single polarisation optical filters for wavelength division multiplexing (WDM) applications. Precise determination of grating characteristics is needed to aid device design, particularly taking into account the polarisation of the illuminating light. The authors report results concerning the production and characterisation of Bragg gratings in high birefringence fibre. Birefringence is measured by the wavelength dependence of the beat length, and from the Bragg grating reflection bands, for three common high birefringence fibres. Characterisation of the gratings when subjected to transversal strain and temperature is described, as well as results of the use of the grating to measure, simultaneously, those two parameters.

Abstract
A new online identification methodology for estimation of the rotor flux components and the main electrical parameters of vector controlled induction motors is presented in this paper. The induction motor model is referred to the rotor reference frame for estimation of rotor flux and rotor parameters, and referred to the stator reference frame to estimate stator parameters. The stator parameters estimation is achieved by a prediction error method based on a model structure described by a linear regression that is independent of rotor speed and rotor parameters. The rotor flux components and rotor parameters are estimated by a reduced order extended Kalman filter, using a 4th-order state-space model structure where the state equation is described by matrices that are diagonal and independent of rotor speed as well as stator parameters. Both methods work in a boot-strap manner. © 2003 IEEE.

Abstract
The complex and extensive nature of urban environments creates difficulties to the task of generating virtual models. Thus a great effort in terms of human resources, time and money is needed. Nevertheless a large number of professionals and institutions devout efforts to gather and analyse data from these urban environments. As data is usually stored in a digital format, it becomes a valuable asset to incorporate it in the modelling process of virtual environments. This paper presents a three-dimensional modelling system with interoperable access to data in diverse formats and digital support, drived by an L-system based modelling process that automatically generates initial solutions for virtual environments, which can be incrementally improved.

Abstract
This paper addresses the problem of parameter estimation of continuous-time systems using samples of its input-output data. We propose a method based on the bilinear transformation to obtain an equivalent discrete-time model. Introducing a new, polynomial pre-filter it is possible to compute the physical parameters via inverse mapping between the discrete-time and the continuous-time models. A simulation example is given to illustrate the noise effects in the parameter estimation results. Using experimental results, we demonstrate the ability of the estimator to handle real measurement problems.