STRUCTURAL MONITORING OF HYBRID SPECIMENS AT EARLY AGE USING FIBRE OPTIC SENSORS
Hybrid structures, notably bridges, consisting of steel girders and concrete decks, are designed to explo it in the best way the mechanical properties of both materials. In order to guarantee safe, durable and low-cost service of such structures, a long-term quality and a robust connection between steel and concrete must be guaranteed. Even if experience in construction, maintenance and exploitation of these structures is large, a good and long-lived connection remains a challenging point in their realisation. This is mainly due to the initial incompatibility in the dimensional behaviour of two materials: early and very early age deformations of concrete (thermal expansion and total shrinkage) generate stresses in both materials even before service and imperils their good interaction. With the intention of a better understanding and an accurate numerical modelling of the steelconcrete connection in hybrid structures, measurements are indispensable and, in particular the deformation evolution in both materials during the early and very early age of concrete. In this paper we present examples of this type of measurements, the monitoring of the total dimensional evolution of hybrid elements, the determination of hardening time of concrete and structural monolithisation and, indirectly, the determination of concrete’s Young modulus evolution. An approach to concrete delamination detection is also assessed. All these parameters are evaluated using fibre optic sensors directly embedded in the fresh concrete or attached to steel elements. Their high accuracy, longterm stability and especially their ability to measure early and very early deformation of concrete are essential for monitoring of mentioned parameters.
Fiber Bragg Grating Sensors for Real Time Monitoring of Early Age Curing and Shrinkage of Different Metakaolin-Based Inorganic Binders
In this paper, we report on the experimental assessment of real-time temperature and shrinkage early age monitoring of geopolymer matrices, by means of embedded fiber Bragg gratings (FBGs). The FBG sensors were properly designed and packaged in order to discriminate shrinkage and temperature behaviors. The proposed system allows for controlling the rheology of the binding systems made by metakaolin geopolymer. Hence, a series of experiments were conducted on different kind of materials, and confirms that FBGs represent a valid method for simultaneous temperature and shrinkage measurements with a temperature resolution of 0.1 °C and strain resolution of  $1\mu \varepsilon $ .
An intelligent control system for ventilators.
This study reports on a ventilator system that consists of several intelligent modules for controlling ventilator operation. These modules are software programs in two controllers. One controller is a personal computer used for diagnoses, determining settings and checking the effects of settings. The other controller is a single-chip microprocessor in a ventilator that controls the ventilator's settings in accordance with the computer settings. After setting up the system, an artificial lung model simulating a patient's lung is used to test the system. The result of test run indicated that it always responds to a patient's lung condition in a stable manner. Thus, the proposed system with its intelligent modules may assist clinicians in caring for patients and managing ventilator operation.