Abstract
The Feedfirst Intelligent Monitoring System is a novel tool for intelligent monitoring of fish nurseries in aquaculture scenarios, mainly focusing on monitoring three essential items: water quality control, biomass estimation, and automated feeding. The system is based on machine vision techniques for fish larvae population size detection, and larvae biomass estimation is monitored through size measurement. We also show that the perception-actuation loop in automated fish tanks can be closed by using the vision system output to influence feeding procedures. The proposed solution was tested in a real tank in an aquaculture setting with real-time performance and logging capabilities.

Abstract
This paper addresses the problem of position determination based on coherence of phases of a set of received sinusoidal acoustic waves. It describes an easily implementable test bed to assess the feasibility of carrier-phase-based differential ranging techiques for precise positioning applications in indoor environments. Futhermore, the use of a discrete set of frequencies fits the scope of using signals of opportunity, such as broadcast stations in RF. Acoustic waves are, themselves, relevant for positioning in specific environments, such as underwater. The main subject of the paper is the formulation and solution of the position determination goal as an n-dimensional integer optimization problem. This n-dimensional problem can be expressed as a weighted least-squares minimization problem with real and integer variables. The associated integer least-squares problem can be solved efficiently in practice as shown. This work is illustrated with some experimental data and a critical analysis of the obtained results.

Abstract
Differential group delay (DGD) generation by inducing birefringence in uniform fiber Bragg gratings (FBG) is studied. Applying a transverse load, a birefringence is induced on a uniform FBG creating a tunable differential group delay. A theoretical behavior of this phenomenon is presented being in good agreement with the experimental results obtained. A maximum experimental tunable DGD of similar to 60 ps was obtained with this induced birefringent process in the uniform FBG. (C) 2007 Wiley Periodicals. Inc.

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