Petr Fidler, Petr Beneš
MEASUREMENT OF SURFACE DISPLACEMENT EXCITED BY EMAT TRANSDUCER

The article discusses the measurement of surface displacement of an electrically conductive solid material. Deflection is excited by electro-magneto-acoustic transducer (hereinafter referred to as EMAT). Measurement is realized by laser interferometer. In our research the precise surface displacement measurement is necessary for two reasons. First is EMAT transducer numerical model convergence verification, second is the experimental optimization of EMAT transducer parameters such as sensitivity, frequency and direction characteristics. Used laser interferometer allows the accurate assessment of surface displacement in a relatively small item, which gives an advantage over using piezoelectric acoustic emission sensors that are limited by aperture effect at small wavelengths. In addition, laser interferometer is capable of surface displacement measuring directly under the EMAT device, which is very difficult with using other methods.

Riadh Hannachi, Zaccaria Silvestri, Daniel du Colombier, Patrick Pinot
USE OF MIRAGE EFFECT FOR THE DETECTION OF ADSORPTION OF ORGANIC MOLECULES ON THE SURFACE Pt – 10% Ir ALLOY OF MASS STANDARD

One among factors responsible of the instability of mass standard is the adsorption and desorption induced by the cleaning products. An optical non-contact method based on mirage effect is proposed to investigate the adsorption/desorption of cleaning solvents on the surface of mass standards at conditions close to normal temperature and pressure (NTP). A model developed for the mirage effect when physical adsorption occurs on a non-porous sample under NTP conditions is recalled. The experimental results of the mirage deflection obtained, in the case of platinum iridium alloy with ethanol itrogen and ether itrogen mixture, and the relation between the phase of the mirage deflection and the adsorption isotherm allow the measurement of the parameters characterizing the adsorption process, such as the amount of adsorbed matter in the first monolayer.

Gaber Beges, Janko Drnovšek
FLAT SURFACE TEMPERATURE PROBE INFLUENCE ON TEMPERATURE MEASUREMENT

This paper deals with the influence of the flat surface temperature probe measuring temperature. Different measurement approaches for measuring surface temperature are possible. For the purpose of safety testing of household appliances surface temperature measurements are very important. General requirements are presented in European standards, which support requirements in European Low Voltage Directive 2006/95/EC. Paper introduces comparison of temperature measurement between attached thermocouple on the measured surface and measurement with flat surface temperature probe. As a heat generator an oven and a temperature artefact are used. Probes and thermocouples are applied to the surface in horizontal and vertical position, using also different force for application of probes. Reference temperature was measured by J-type fine-wire (0.2 mm) thermocouple. Two probes were homemade according to requirements in [2], but one with fine-wire (0.2 mm) thermocouple and one with 0.5 mm of thermocouple wire diameter. The third compared probe was a commercial one not in accordance with the standard requirement for dimensions. Results showed that only probe with fine-wire thermocouple can be used for the measurement of surface temperature. It's deviation from the reference thermocouple attached to the surface was the lowest. The other probes also influenced the unit measured so that the temperature dropped.

Klaus Oppermann, Bernhard Zagar
MATERIAL CHARACTARIZATION FOR A TERNEOL-D BASED FORCE SENSOR

In this paper the magneto-elastic effect is taken under further investigation, to determine the utility of the novel material Terfenol-D in force sensor applications. A measurement set-up is designed and the characteristic material parameters like magnetization diagram, butterfly diagram and the reluctance dependent on the applied mechanical load is determined. The results demonstrate that it is possible to sense both static and dynamic forces with only a single read out coil. The resultant simple arrangement of the set-up combined with the not fully utilized overload capability given by the elastic range of the sensing material Terfenol-D guarantees its robustness.

H. Röck, Felix Koschmieder
ADVANCED PHASOR CONTROL FOR A CORIOLIS MASS FLOW METER (CMFM)

Advanced control of Coriolis Mass Flow Meters (CMFM) is crucial in situations with multiphase flow and absolutely necessary to prevent the meter from stalling. A high dynamic response of the meter is also of great importance in order to realize advanced features s.a. parameter identification for self-diagnosis or detection of changes in sensitivity and zero. In [4] a cyclic stimulation of the coriolis-mode of the CMFM, representing a virtual mass flow, is presented for generating diagnostic data and marks a major step towards the realization of such features. The presented phasor control scheme for phasors with quasi stationary frequencies reduces the cycle time by a factor of two with respect to [6] and allows to handle situations with multiphase flow. The control performance is much better than reported before but can still be enhanced if the scheme is extended to time-varying frequencies.
In the paper only the drive-mode of the CMFM(single straight pipe) is investigated. The control objective is to stimulate the oscillation system in its a priori unknown eigenfrequency ω₀₁ by phase control and to allow for phase and amplitude control simultaneously. This is different to conventional control schemes where phase and amplitude control have to be separated in time in order to work properly. The control scheme is tested in simulation and realized in an experimental setup of a CMFM.