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Page 745 of 936 Results 7441 - 7450 of 9356

N.Kontos, L.Theodorakis, E.Hristoforou
RESONANCE TECHNIQUES FOR INDUCTIVE SENSOR APPLICATIONS

This presentation describes the block diagram, explains the principal idea and shows the experimental results of a displacement and stress sensor. Both applications are based on inductive effects, while the examination of the sensor response determines the dependence of the permeability for all the different tested materials (magnetic cores) on the excitation frequency, the applied stress and the displacement of the material.

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.

V. Karagiannis, D. Bargiotas, S. Voliotis, C. Manassis
ON LVDT RESPONSE USING GLASS COVERED WIRES

In this paper we present results on the response of linear variable differential transformers (LVDT) using FeSiB glass covered wires as active cores. First we demonstrate that the noise level of the sensor decreases with the magnetostriction coefficient of the magnetic core of the wire. Magnetic noise is further decreased after heat treatment, magnetic annealing and stress-current annealing. These results are in relatively acceptable agreement with results presented in the past by other research groups.

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.

Helena Ramos, M. Pereira, V. Viegas, O. Postolache, P. Girão
A CENTRONICS BASED TRANSDUCER INDEPENDENT INTERFACE (TII) FULLY COMPLIANT WITH 1451.2 STD.

The paper reports the tests conducted on a dedicated Transducer Independent Interface (TII) to check its compliance with standard IEEE 1451.2 specifications. The interface was built using a synchronous data transfer based on the Serial Peripheral Interface (SPI) protocol integrated in a PIC microcontroller used as the Smart Transducer Interface Module (STIM) and the Centronics port of the PC, used as the Network Capable Application Processor (NCAP’s TII port). The description of each line and the connections are also presented.
The working prototype of the STIM controlled by a NCAP module was implemented to connect several transducers without communication capabilities used in a water quality monitoring network. The NCAP, also described in the paper, is emulated in a PC and it was fully developed using LabVIEW 6.1.

Umberto Pogliano, Gian Carlo Bosco, Marco Lanzillotti
VALIDATION OF THE NEW AUTOMATIC SYSTEM FOR AC VOLTAGE COMPARISONS

A system for the automatic comparisons of ac voltage, ac current and ac-dc transfer has been built, which simplifies the management of the whole traceability chain from national standards to the instruments under test. The validation process for ac-voltage and ac-dc transfer has shown the functionality of the system, a high repeatability and self-consistency of the results and a full compatibility with measurements made manually and by the previous automatic system.

Andrea Bernieri, Luigi Ferrigno, Marco Laracca, Salvatore Ventre
THE METROLOGICAL CHARACTERIZATION AND OPTIMIZATION OF A LOW COST MEASUREMENT SYSTEM FOR INDUCTANCE TOMOGRAPHY ON CONDUCTIVE MATERIALS

The paper proposes the improvement and the metrological characterization of a measurement system for non-destructive testing on conductive materials. The limits showed by the previous realized prototype are discussed and overcome using a new hardware and software solution. The metrological characterization in terms of probe linearity, measurement uncertainty, and crack detection sensibility is reported. The experimental analysis carried out using the proposed system on specimens with known defects shows a good agreement between the estimated and expected results.

Vladimir Kneller
QUANTITIES TRANSFORMATION: GENERAL TECHNIQUES AND ACCURACY IMPROVEMENT

The process of quantities transformation, which underlies many other processes such as measurement, control, etc. is considered. It is defined as a process of physical realization of the desired functional dependence between the quantities x and y, i.e. y = f(x), interpreted as the specific target-oriented family of causally related events and considered regardless of the physical nature of the participating quantities, i.e. at the structural level. The general methods for realization of the main components of quantities transformation – connecting y and x with a desirable functional relationship and reducing the effect of undesirable factors on this relationship – are revealed and systematized in deductive, logically clear way starting from several known generic principles and mechanisms.

Andrzej Dobrogowski
SOME REMARKS ON MEASUREMENT OF TIME

In the paper some interpretation subtleties of a clock indication and clocks’ comparison are discussed. The same amount of accumulated phase is common to a “second” of different clocks. As we can measure short and long time intervals with the same (or very similar) absolute uncertainty and use a reproducible phenomenon having very short duration in comparison to the length of the interval measured therefore properly designing the measurement we can get very small uncertainty of interval’s measurement. It is explained why making the repetition series of the phenomenon longer improves the quality of averaging. Substitution of the difference of times of two clocks in the same instant and the time interval between two instants marked by each clock with the same date is justified.

Alexandru Salceanu, Valeriu David, Mihai Cretu
MEASURING AND INTERPRETING THE CMOS IC VARIABLE INPUT IMPEDANCE VERSUS ESD STRESS

The paper presents a comparative method (and the related results) for measuring the various impedances of a Si-gate CMOS digital circuit, very useful for the study of the dual input protection configuration, with respect to an ESD pulse. The results of the performed measurements are interpreted according to the behaviour of the two main protective circuits and are useful to verify the waveform at the output of a self-manufactured ESD tester, the load values being essential.

Page 745 of 936 Results 7441 - 7450 of 9356