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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.

Leopoldo Angrisani, Antonio Langella, Michele Vadursi
NEW DIGITAL SIGNAL-PROCESSING APPROACHES FOR MEASURING POWER CCDF CURVES

Signals peculiar to modern telecommunication systems are characterized by higher peak-to-average power ratios than in the past and can potentially lead to higher distortion in amplification stages if signal power statistics are not accounted for properly. CCDF (Complementary Cumulative Distribution Function) curves are an effective way of fully specifying signal power characteristics. Some high performance analysers, currently available on the market, carry out CCDF measurements through a demodulation of the radiofrequency signal and the application of custom digital signal-processing algorithms to the samples of the baseband components thus retrieved. Two alternative digital signal-processing approaches for measuring CCDF curves are presented in the paper. The major advantage they offer consists in the absence of demodulation; they are, in fact, based on original algorithms that are directly applied to the samples of the radiofrequency signal.

Alexandru Salceanu, Mihai Cretu, Valeriu David, Eduard Lunca
DETERMINING ESD THREATS FOR A HUMAN-FURNITURE MODEL IN MOTOR VEHICLES

The paper presents some performed measurements and investigations in the framework of the triboelectricity developed in a motor vehicle. The concern about ESD induced failures is growing up in the same manner as the electronic content of an up-to-date car. Assuming the furniture ESD model, were measured or evaluated its parameters for the situation “person inside the vehicle” and “person getting out from the vehicle”. With an electrostatic head were measured the different values for ESD charging inside the vehicle. This study offers useful information in order to develop an ESD simulator and to reduce the fails and errors due to ESD phenomena in a modern car.

Dušan Agrež
POWER MEASUREMENT IN THE NON-COHERENT SAMPLING

An algorithm to improve the estimation of the active power of electrical systems in the non-coherent sampling is proposed in this paper. It is based on smoothing sampled data by windowing, and then averaging of the DFT (discrete Fourier transform) coefficients in the frequency domain to reduce leakage effects. The simulation and experimental results are presented showing that averaging of DFT coefficients provides better estimation of the active power then only by windowing. The use of a suitable algorithm depends on positions of the frequency components, on a number of observed periods, and on signal to noise ratio.

Tomasz Tarasiuk, Mariusz Szweda
A FEW REMARKS ABOUT NOTCHING ANALYSIS - CASE STUDY

This paper has been focused on the problem of analysis of notching occurring in electric power systems. Especially a choice of appropriate sampling frequency and its consequence for results of the analysis have been considered. Moreover, the problem of wavelet filter length and, in some respect, wavelet family has been analyzed as well. All analyses have been based on the real voltage samples, registered in the real isolated electric power system, namely ship’s system, during two different electric power plant configurations. Finally, results of the research have been commented on with respect of its impact on a whole device for power quality analysis.

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