IMEKO Event Proceedings Search

   

Page 227 of 977 Results 2261 - 2270 of 9762

Antonio Boscolo, Alessandro Cont
PLANTS AND CULTIVATIONS KNOWLEDGE-BASED DIAGNOSTIC SYSTEM

Parasitic attacks and environmental stresses may decrease the yield of crop plants and even cause damages to forests. A diagnostic system has been developed for monitoring early stress states in plants in order to set up the most suited intervention and keep plants in their optimal state. The study of natural leaf fluorescence gives useful informations about photosynthetic apparatus so that it appears to be a valid inspection tool for monitoring plants metabolism. The instrument integrates the knowledges of human experts and laboratory diagnostic techniques for an on-site and non-intrusive analysis and a neuro-fuzzy data fusion for the overall response about plants health.

Roman Malarić, Ivan Leniček
RESISTANCE MEASUREMENT CAPABILITIES OF THE PRIMARY ELECTROMAGNETIC LABORATORY

Ensuring a system of international traceability of its standards is the main task of Primary Electromagnetic Laboratory (PEL). PEL has established resistance traceability for the group of resistance standards in the range of 1 mΩ to 100 MΩ. The preferred way of resistance standard calibration at PEL is self-developed method using two digital voltmeters, which are measuring voltage drops on serially connected standard resistors. The method is also used for calibration purposes of all types of resistors, decades, shunts and resistance measuring devices. Another method for calibrating high-ohm resistance standards is currently being developed to extend the resistance measuring capability of PEL to the GΩ range.

Ivan Leniček
INFLUENCE OF DVM'S INPUT PARAMETERS ON DVM-BASED HIGH-OHM RESISTANCE COMPARISON

Establishment and maintenance of resistance standard traceability is one of the main tasks of Primary Electromagnetic Laboratory (PEL) within the Faculty of Electrical Engineering and Computing of the University of Zagreb. For the purpose of accurate resistance standards comparison a digital voltmeter (DVM) based method has been designed and realized. When measuring resistance standards greater than 10 MΩ capabilities of the method are restricted due to influence of DVM's input parameters: input DVM's resistance, input offset current and input capacitance. Determination of DVM's input parameters and their contribution to the overall high-ohm resistance comparison uncertainty has been presented in this paper. The possibility of use of DVM-based method for gigaohm value resistors comparison has also been investigated.

Zbigniew Rucki, Zdzislaw Szczepanik
MEASUREMENT OF DISTRIBUTION OF ELECTRICAL RESISTIVITY USING MULTI-ELECTRODE CONDUCTIVITY CELL

In the paper application of multi-electrode conductivity cell is suggested to study the distribution of electrical resistivity of electrolyte solutions. Two- and four-electrode methods of measurement were analysed. Results of modelling of potential and current density distribution within conductivity cell are presented. Preliminary results of measurements verifying usability of the proposed method are given.

Umberto Pogliano, Gian Carlo Bosco, Francisco Chueco, Marco Lanzillotti
AC TRACEABILITY IN THE MILLIVOLT RANGE UP TO 1 MHz BY MEANS OF A WIDEBAND TRANFORMER

At IEN the application of new procedures for the calibration of ac voltages in the millivolt range is now being developed. In this paper a specific method based on a high precision inductive divider and wideband ransformers is analysed. The experimental determination of the transformer parameters shows that the generation of calibrated ac voltages is possible with an uncertainty better than 50 parts in 106 down to 10 mV.

Uwe Frühauf, Ernst-Georg Kranz, Hellmut Leuterer
AUTO-CORRECTION AND DESIGN-FOR-TESTABILITY IN EMBEDDED MEASUREMENT SYSTEMS

For investigation and training of students in the field of high resolution measurement technology was built an embedded measurement system with 16 bit resolution and additional modules for self-diagnostics and utocorrection, including methods of design-for-testability in analogue circuits.

Luca Callegaro, Francesca Durbiano
CAPACITANCE MEASUREMENTS AT ULTRA-ACOUSTIC FREQUENCY: FIRST EXPERIMENTS AT IEN

The Istituto Elettrotecnico Nazionale Galileo Ferraris (IEN), the Primary Metrological Institute for electrical quantities in Italy, started efforts toward traceable measurements of impedance standards at ultra-acoustic frequencies (up to 10 MHz). We report on the implementation of a calibration method for capacitance standards, first described by K. Suzuki. The method, starting from one-port impedance spectra measured with a commercial automatic network analyzer, predicts the frequency dependence of the corresponding four terminalpair impedance for the same standard, impossible to measure directly in a traceable way. First measurements on commercial capacitance standards (nominal value 100 and 1000 pF), suited for ighfrequency measurements and employed for calibration of commercial RLC bridges, have been carried out. The results are compared with published data from implementations of the same method.

Maurizio Caciotta
STUDY OF A STANDARD FOR INFORMATIVE CALIBRATION PROCEDURE IN INSTRUMENTATION CALIBRATION

The calibration cost of an instrument is so expensive that is necessary, to reduce the number of calibrated points, in the scale. There is the necessity to exploit as well as possible the metrological valence of few calibrated points to extend all over the instrumental range. The choice of the number and the position of such few points is the problem faced in the work. Utilizing the Shannon sampling procedure in the transposed domain of the input entities of the instrument, with respect to the time, the truncation error of the cardinal serie has faced utilizing the Helms and Thomas upper bound evaluation. To enhance the efficiency of the procedure, has been utilized the minimax procedure searching the optimal indication on better determination. In every case the efficiency of the procedure is lower on the edge of the instrumental scale. To upgrade the edge calibration, making as even as possible the calibration, upon the scale, one has been utilized the generalized sampling theorem by Papoulis that allows to chose the calibration points more frequent at the edge, with respect of the central part of the scale. An algorithm to guide the calibration procedure is tempted.

Radek Sedláček, Jaroslav Boháček
ELIMINATION OF UNWANTED VOLTAGE DROPS ACROSS THE LINKS BETWEEN FOUR TERMINAL – PAIR COMPONENTS CONNECTED IN SERIES

Two possible methods of eliminating unwanted voltage drops in four terminal-pair bridge circuits are discussed, namely employment of combining networks and injection of compensation voltages. As an economical and practical way of producing these voltages, application of a slave digital synthesis (DSS) generator, directly synchronized with the source of the bridge supply voltage, is proposed. A possible design of such a generator, based on employment of a DSP evaluation board, is described.

Kalogeropoulos Stylianos, Kotsilieris Theodoros, Mihalas Aggelos, Loumos Vassileios, Kayafas Eleftherios
AN AUTOMATIC QUALITY ASSESSMENT METHODOLOGY FOR ABSTRACT TEST SUITES

Testing is a major factor in the successful development of efficient and reliable telecommunication implementations. The need for a unified approach in conformance testing, led to the publication of the Conformance Testing Methodology and Framework (CTMF) standard ISO/IEC 9646 ([1], [2], [3], [4], [5], [6], [7]). The Tree and Tabular Combined Notation (TTCN), is the standard language used to specify Abstract Test Suites (ATSs) [3]. It is observed that quality of TTCN test suites published by international committees (ETSI, ITU-T) is often regarded as poor. This is an indication of weaknesses in current Quality Assessment (QA) practices. In this paper an automatic quality assessment method for Abstract Test Suites is defined, tested and evaluated.

Page 227 of 977 Results 2261 - 2270 of 9762