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...
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...
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...
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.
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.
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.
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...
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...
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.
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...