Michal Malátek, Pavel Ripka, Petr Kašpar, Antonín Platil, Ludek Kraus
ELECTRONICS FOR MI CURRENT SENSOR

This paper deals with an electronics developed for controlling of contactless current sensor based on magnetoimpedance (MI) effect. The demands required on design of the electronics came from current sensor structure, which takes into account suppression of temperature dependences of impedance of MI material. The electronics, due to its advantageous design, can serve also as the electronics of single and double-cored MI sensors in general.

Michael Gürtner, Norbert Neumann, Friedrich Schneider
LOW POWER NDIR-CO₂-SENSOR FOR BUILDING AUTOMATION

Besides humidity the content of CO₂ is the most important air quality parameter in private homes. On the other hand power consumption for heating and air conditioning contributes essentially to the worldwide energy problems. An effective way to reduce it is to develop decentralized air conditioning systems consisting of optimal matched components. A major component is the air quality sensor which has not only to acquire CO₂ but also humidity and temperature. Further on such a sensor needs powerful data processing features and an interface to a bus system (either by TP or RF). The design requirements for it are different to those for sensors in industrial applications. Main targets are reliability, no maintenance and no recalibration for several years, low power consumption, small size and reasonable costs rather than high precision.

S. Vaitsi, E. Hristoforou
FREQUENCY AND TEMPERATURE DEPENDENCE OF THE DIELECTRIC CONSTANT IN Ba_1-xSr_xTiO₃ PELLETS

In this paper we illustrate results concerning measurements of the real and imaginary part of the dielectric constant of BaTiO₃ pellets doped with Sr, as a function of temperature and frequency. Substitution of Ba with Sr was up to 40% (x=0.1, 0.2, 0.3, 0.4, 0.5). It is shown that the Curie temperature of the ferroelectric to paraelectric transition is a monotonic dependence of Sr% and has an influence in the dielectric constant. Furthermore, frequency dependence also illustrates that oscillation ability of the electric dipoles is not monotonic, being dependent on the ferroelectric dipole interaction.

C. Manassis, V. Karagiannis, D. Bargiotas, S. Voliotis, T. Maris
FLUID VELOCITY PROFILE METERS USING FESIB GLASS COVERED WIRES

In this paper we present a fluid flow-meter based on the inductive response of glass covered FeSiB amorphous wires, arranged as vertical active cores with respect to the flow of a liquid in a pipe of circular or rectangular diameter. Arrays of parallel FeSiB glass covered wires, fixed at the one end and free at the other are set normal to the fluid flow inside of an array of thin coils, thus covering the whole cross section of the fluid conduit. An excitation coil is also used for static flow measurements. The displacement of each glass covered wire corresponds to the local velocity of the fluid. It has been determined that the uncertainty of the voltage output dependence on the fluid flow is better than 1%. So, the profile of the fluid velocity along the cross section of the fluid conduit can be determined.

Salvatore Baglio, Vito Caruso, Nicola Pitrone, Nicolò Savalli
SENSORS FOR CONTACTLESS ESTIMATION OF ICE CONCENTRATION IN “ICE SLURRY” FLUIDS

This paper deals with the problem of estimating the ice fraction in ice slurry fluids flowing into the pipes of industrial refrigeration apparatus based on secondary refrigerants. Such measurements must be performed in a non invasive way and the sensors must face with severe environmental conditions.
Two different sensors have been developed and are presented here. In particular, an optical sensor is presented that relates the transmission of signals with the ice density, while a capacitive sensor is proposed as well exploiting the effects of ice particles concentration on the ice slurry fluid permittivity.
Experimental prototypes have been realized for each one of the sensors proposed here. These sensors have been applied to an experimental refrigeration system that allows obtaining different percentage of ice in a controlled and reproducible manner. The experimental results obtained for each one of the sensors are reported showing the suitability of the approach. Some conclusive remarks are also given in order to compare the sensor performances.