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Page 744 of 936 Results 7431 - 7440 of 9356

D. Bargiotas, S. Voliotis, V. Karagiannis, C. Manassis
LOAD SENSORS BASED ON THE MAGNETOSTRICTIVE DELAY LINE TECHNIQUE

In this paper we present results on load sensors based on the magnetostrictive delay technique. The sensors translate the displacement of soft magnetic plate, hard magnetic disk and aluminium disk into force with respect to three different magnetostrictive delay line set-ups. The range of displacement determines the range of measurable load. Stainless steel springs have been used as active core supports. The best results both in sensitivity and repeatability have been obtained using soft magnetic plate as active core.

W. Domanski, P. Chaitas, J. Zakrzewski, Th. Laopoulos
A GRAPHICAL APPROACH TO ESTIMATION OF GAS CONCENTRATION WITH SnO2 SENSORS

Electronic systems for automated monitoring of the presence of dangerous gases are available nowadays in different configurations and with quite different capabilities. This work is presenting the development of an electronic instrument for monitoring the level of two gases (namely CO and CH4) aiming for possible use in coalmines. The instrument is using SnO2 sensors and is based on a graphical estimation of the concentration of each of the two gases realised by a combination of the information from the calibration curves of the two sensors. In this way, instead of trying to suppress the well-known secondary sensitivity of these gas sensors, this method is estimating the two concentrations by a computerised approximation of the operating point on the calibration curves.

Cristian Fosalau, Cristian Zet, Marinel Temneanu, Mihai Antoniu
A NOVEL CURRENT SENSOR USING MAGNETOSTRICTIVE AMORPHOUS WIRES

The current sensor presented in the paper is built around a relatively new category of materials expressed by magnetic amorphous wires. Its operating principle is based on the Matteucci effect occurring in amorphous wires showing high level of magnetostriction. The wire is wound around the conductor through which the current to be measured flows. Under certain conditions, at the ends of the wire sharp voltage pulses appear whose amplitude depends on the intensity of the circumferential magnetic field generated on the conductor surface and, implicitly, on the current intensity.

Valeriu David, Mihai Cretu, Alexandru Salceanu
ON THE LOOP SENSORS FOR THE ELECTROMAGNETIC FIELD MEASUREMENT

In this paper we present an overview of the electromagnetic field loop sensors measurement performances. The loop sensors are much utilised in electromagnetic field measurements (magnetic field measurement, simultaneous magnetic and electric field measurements). The knowledge of the influence of the dimensions sensor on measurement performances of the electromagnetic field is important both in sensor optimisation, and in the selection of the sensor for a certain application. The results of time domain measurements of the magnetic field near some appliances, made with an active magnetic field sensor, are presented.

Christian Eugène, Michaël Demeyere
AMBULATORY MEASUREMENTS OF DIMENSIONAL QUANTITIES BY LASER TRIANGULATION UNDER STRUCTURED LIGHTING

The first part of the paper, mainly of tutorial nature, will be devoted to the presentation of the basic principles of 3D measurements by triangulation under lighting structured by laser planes. The metrological aspects will then be considered, namely the calibration of the measuring set-up. Finally, a series of industrial applications developed in the laboratory and oriented towards the conception of new field instruments (non-contact measurement of linear objects, of the angle between planes, of the diameter of cylinders, …) will be presented. The experimental results show a general accuracy of the order of one percent.

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.

S. Cherepov, O. Hesse, G. Mook, S. Pankratyev, V. Uchanin
OPTIMISATION OF LOW FREQUENCY EDDY CURRENT SENSORS USING IMPROVED INDUCTIVE COILS AND HIGHLY SENSITIVE AMR AND GMR SENSOR MODULES

Optimisation of low frequency eddy current probes was performed using traditional inductive coils and commercially available AMR and GMR sensors and sensor modules. Results of three groups are presented demonstrating that such kind of eddy current probes show high penetration and sensitivity at low testing frequencies. The lack of objective criteria for comparison had to be stated. A Round Robin test is proposed between the presented groups with more objective criteria to be established before and during the test.

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.

Jan Fischer, Tomáš Radil, Jan Šedivý
THE TRIANGULATION METHOD OF CONTACT-LESS DIMENSION MEASUREMENT USING AN AREA CMOS IMAGING SENSOR

The so-called triangulation method of contact-less dimension measurement determines the measured object’s dimension from its shadow projected on an imaging sensor without lens. A point light source is used to illuminate the measured object. The so far used linear CCD sensors introduced a considerable uncertainty to the measurement. Application of area CMOS imaging sensors improves the measurement uncertainty and enables to use some new measurement methods. A special CMOS measuring camera was designed for this purpose.

S. Vaitsi, E. Hristoforou
FREQUENCY AND TEMPERATURE DEPENDENCE OF THE DIELECTRIC CONSTANT IN Ba1-xSrxTiO3 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.

Page 744 of 936 Results 7431 - 7440 of 9356