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Page 842 of 907 Results 8411 - 8420 of 9067

Wlodzimierz Pogribny, Igor Rozhankiwsky, Tadeusz Leszczynski
MEASUREMENT OF SHORT NOISY SIGNAL PARAMETERS WITH THE USE OF SIGN DM

Usually correlation analysis (CA) is realized in Pulse Code Modulation (PCM) format that needs numerous mathematical operations with the large word length that limits the fast-acting of processing as well as the use of its to the measurement of wide-band noisy signals in real time. In this paper the use of signal representation in Sign Delta Modulation (SignDM) format has been proposed in order to increase the efficiency of the real time CA of short hardly noised signals. The SignDM codes are specified by comparing the values of differences between signal samples in PCM format with a differential zone which is defined a priori. These two bit codes reflect the signal character and are suitable for CA as well. In this paper there are presented the fast and exact algorithms of the SignDM CA, as well as the computer simulation results for resolution of CA of short noisy signals at the various differential zone and initial phases.

Marko Jurcevic, Mladen Boršic
INTERNET-ENABLED CALIBRATION SERVICES: THE REMOTE CONTROL OF INSTRUMENTS

A growing number of measurements in commercial and industrial sector needs to refer to the traceability to the national (and also international) standards. Since the internet-enabled metrology is rapidly developing in the recent years, it offers new possibilities for calibration services. This paper focuses on the problem of the visualization of the internet-enabled calibration process and instruments. The main goal is to identify the solution for real-time data monitoring and control of measurement equipment.

Artur Wollek
INFLUENCE CRITERIONS OF QUALITY TO THE WEIGHT WINDOWS SELECTION

Weight filtration is performed in time domain through multiplying values of appropriate samples by a weighting function and summing the yielded products along the entire window length. The number of weight windows is unlimited. In his paper author is trying to define the filtration quality and its influence to the weight window selection.

R. Lapuh, R. Voncina
GUIDELINES FOR DETERMINATION AND EVALUATION OF LOW-FREQUENCY ELECTROMAGNETIC FIELDS OF HIGH-VOLTAGE POWER STATIONS

Enforcement of Directive 40/2004/EC binds the EU member countries to define their legislative proceedings on the minimum health and safety requirements regarding the exposure of workers to the risk arising from physical agents (electromagnetic fields).
In this paper guidelines for the determination and evaluation of low-frequency electromagnetic fields of high-voltage power stations are proposed. They are based on experiences gained with numerical calculations and measurements and are compatible with measurement practices and demands of international labot conventions and EU Directives.

Laurentiu-Dan Milici, Mihai Cretu, Mariana-Rodica Milici
FRACTAL ANALISYS METHODS IN ESTIMATION AND PREDICTION OF SOME METEOROLOGICAL PARAMETERS

The estimating methods of the meteorological parameters at Meteorology and Hydrology National Agency (ANMH) standard offers sufficient data to answered at the requirements of the population. Thus, it was ascertained that through the determination of fractal dimension of temporal series obtains different values for neighboring zones, values which should complete the already existing information and which should offer supplementary data concerning the efficiency of such stations.

Pasquale Arpaia, Fabrizio Clemente, Mario Rapone, Carmine Romanucci
EVOLUTIONARY PATTERN RECOGNITION FOR MEASUREMENT OF VEHICLE EMISSION FACTORS IN CRITICAL DRIVING CONDITIONS

A research project on the measurement of emission factors in critical driving conditions arising from a cooperation among University of Sannio, Istituto Motori of CNR, and some companies of Italian Regione Campania is started. In particular, in this paper, a procedure of automatic feature extraction and data classification of vehicle driving sequences by means of Wavelet analysis and Cultural Algorithms is proposed. The procedure improves the lack of sensitivity of the state-of-the-art statistical methods to variations of vehicles instantaneous kinematic parameters (e.g. speed, acceleration) through a simple heuristic link between vehicle speed and road traffic data.

Jan Hlavácek, Karel Draxler, Radek Procházka
CURRENT TRANSFORMER USAGE FOR NONHARMONIC PERIODIC CURRENTS

This paper deals with composite error determination of current transformers (CT) for purpose of nonharmonic periodic current measurements. The experiment was performed for typical nonharmonic periodic waveforms that occur in power grids with frequency 50 Hz. The area of measurements was extended also for higher fundamental frequency values.

Sergey V. Muravyov, Valery N. Borikov, Stanislav A. Kaysanov
COMPUTER SYSTEM FOR MEASUREMENT OF WELDING PROCESS PARAMETERS

This paper presents both hardware and software of system for measurement of welding process electric parameters.
The distinctive feature of the system is its application for control of the process of high-quality contact micro-welding of critical destination products which is characterized by the pulse current in the range from 100 A to 20kA and by the pulse duration from a few to hundreds of milliseconds. The system is portable and consists of the measuring coaxial shunt, oscillograph and computer with a software. Structure and main principles of constructing the system components are described. Its technical and metrological parameters are given.

Celso Fabricio de Melo, Ricardo Luiz Araújo, Leonardo Morozowski Ardjomand Nilton S. Ramos Quoirin, Minoru Ikeda, Alexandre Albarello Costa
CALIBRATION OF MAGNETIC FIELD METERS AT 60 Hz USING A HELMHOLTZ COIL: CONSTRUCTIVE ASPECTS AND CALCULATION OF ASSOCIATED UNCERTAINTIES

This paper describes the construction of a Helmholtz coil to be used as a magnetic field generator during the calibration of magnetic field sensors. A magnetic field meter was calibrated using the coil to test its efficiency. The obtained results were then compared to the meter’s calibration sheet.

Pietro Vincenzo Barbaro, Antonio Cataliotti, Valentina Cosentino, Salvatore Nuccio
BEHAVIOUR OF REACTIVE ENERGY METERS IN POLLUTED POWER SYSTEMS

The reactive energy meters used in electric distribution networks are based on a conventional definition of reactive energy (or power) for sinusoidal voltages and currents, containing only the fundamental frequency component. As a consequence, the performances of reactive energy meters in the presence of harmonic distortion are not tested and their accuracy specifications can be very different from the nominal ones, that are evaluated in sinusoidal conditions. In this paper the authors present a comparative study of the performances of different reactive energy meters, both electromechanical and static, in the presence of harmonic distortion; the study is supported by several simulations and experimental tests.

Page 842 of 907 Results 8411 - 8420 of 9067