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CONTENTS
| Antonio Cruz Serra, Pasquale Daponte, Linus Michaeli - ADC and DAC modeling and testing - state of the
art | 231 |
| Janusz Gajda, Ryszard Sroka, Marek Stencel, Tadeusz Zeglen - Data fusion applications in the traffic parameters
measurement | 249 |
| Andrzej Bień, Michał Szyper, Andrzej Wetula - Model study on complex modulation and demodulation of power network voltage
signal loaded with time-variable impedance | 263 |
| Dušan Agrež - Comparison of capacitors by means of a double-channel digitizer | 275 |
| Stanisław Kałuża, Zbigniew Szcześniak - Stabilized temperature measurements based on thermooptic memory
phenomena | 285 |
| Paweł Pawlus - The analysis of slope of surface topography | 299 |
| Zbigniew Szcześniak - Method of processing accuracy enhancement of the photoelectric position transducer
signals | 315 |
| Sanjay Yadav, A. K. Bandyopadhyay - Proficiency testing (PT) program under NABL in the pressure range 7- 70 MPa using
digital pressure calibrator (DPC) | 323 |
ABSTRACTS & FULL PAPERS
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A. CRUZ SERRA1, P. DAPONTE2, L. MICHAELI3
1Technical University of Lisbon, Department of Electrical Engineering and Computers, Portugal
e-mail: acserra@ist.utl.pt
2University of Sannio, Department of Engineering, 82100 Benevento, Italy, e-mail: daponte@unisannio.it
3Technical University of Košice, Department of Electronics and Telecommunications, Slovakia
e-mail: Linus.Michaeli@tuke.sk
ADC AND DAC MODELLING AND TESTING STATE OF THE ART
The analog to digital front ends of measuring instruments affect crucially the interpretation of the signals acquired from the real world into the digital domain and their back presentation. The signal processing in the digital domain due to its stability meets usually the requirements on the uncertainty of the measuring instruments easily. ADCs and DACs influence dominantly the accuracy of instruments and limit the signal dynamics and their applicability. An exact error description and standardized testing methods are required by the end user. Moreover, the simplification of the error description by dominant error parameters is a permanent task for the metrologist and producers. This paper is aimed at providing a metrological overview of ADC and DAC topics by referring to their: i) architectures, ii) modelling and testing, and iii) standardization.
Full paper (340kB): M&MS_2005_231.pdf
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J. GAJDA, R. SROKA, M. STENCEL, T. ZEGLEN
AGH - University of Science and Technology
Faculty of Electrical Engineering, Automatics, Informatics and Electronics
Krakow, Poland, e-mail: jgajda@uci.agh.edu.pl
DATA FUSION APPLICATIONS IN THE TRAFFIC PARAMETERS MEASUREMENT
In the paper the problem of measuring road traffic parameters using systems with complex algorithms for measurement data processing is discussed. A characteristic feature of these systems is utilising there data fusion methods. This way a possibility has been created of linking the knowledge of measuring with an initial knowledge on the measurement object. The authors have shown that these methods allow to decrease measurement uncertainty, increase measurement reliability or limit the influence of the disturbing factors.
Keywords: data fusion, vehicle classification, Weigh-In-Motion, WIM calibration
Full paper (265kB): M&MS_2005_249.pdf
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ANDRZEJ BIEŃ, MICHAŁ SZYPER, ANDRZEJ WETULA
AGH University of Science and Technology, Kraków, Poland
e-mail: abien@uci.agh.edu.pl
MODEL STUDY ON COMPLEX MODULATION AND DEMODULATION OF POWER NETWORK VOLTAGE SIGNAL LOADED WITH TIME-VARIABLE IMPEDANCE
Variability of power network voltage degrades the quality of power supplied to customers. Several power quality measures connected with voltage variability have been agreed on international scale. However, it turns out that the measures of electric power quality determined by the instruments which measure the short-term flicker severity index PST of light sources may lead to ambiguous quality assessment because of different measurement values for the same measured signals. Physical interpretation of phenomenons occurring in power network based on measurement results is therefore difficult. In this article we propose the conception of carrying this kind of analysis using a mathematical model of influence of load variability on power network voltage signal. These analyses rely on detecting factors influencing the signal shape. The article presents part of results including model studies.
Presented results may be, in our opinion, basis for reasonable questioning of correctness, and especially ambiguity of currently used method for measuring time-variability of power network voltage parameters, based on determining flicker severity index. Especially doubtful are the flicker severity index definition and method of calibrating measurement devices based on it.
Considering achieved results, we express the opinion about need for a new, more reliable and unambiguous measure of power network voltage variability caused by load fluctuations. It should consider signal properties, have simple physical interpretation and be simple to calculate.
Keywords: voltage variation, flickermeter, power quality
Full paper (255kB): M&MS_2005_263.pdf
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DUŠAN AGREŽ
University of Ljubljana
Faculty of Electrical Engineering, Slovenia
e-mail: dusan.agrez@fe.uni-lj.si
COMPARISON OF CAPACITORS BY MEANS OF A DOUBLE-CHANNEL DIGITIZER
In the paper, a comparative method of measurement of the capacitors by measuring the voltages across them and phase angle between is presented. In the analysis of errors the systematic loading effects of the connection and their elimination has been described. The reductions of the systematic and the random errors of sampling and quantization have been performed in the frequency domain. Application of the method is possible with support of the modern digital signal processors and with interpolated DFT to improve the accuracy and speed of the measurement.
Keywords: measurement of capacitors, comparative method, error analysis, loading effect, leakage effect
Full paper (168kB): M&MS_2005_275.pdf
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STANISŁAW KAŁUŻA1, ZBIGNIEW SZCZEŚNIAK2
Kielce University of Technology, Poland
1The Chair of Physics, e-mail: fizsk@tu.kielce.pl
2Department of Automatics Devices and Systems, e-mail: Z.Szczesniak@tu.kielce.pl
STABILIZED TEMPERATURE MEASUREMENTS BASED ON THERMOOPTIC MEMORY PHENOMENA
Investigations of non-linear phenomena in A2MX4 (where: A - organic cation or ion of alkaline metal, M - metal, X - halogen) crystals with incommensurate phases are very interesting both from scientific and practical point of view. Some aspects of applications of these crystals to different fields of science and technology are discussed. Thermal hysteresis of birefringence and absorption coefficient, piezooptic, thermooptic and electrooptic effect are observed in selected A2MX4 crystals. This suggests that these materials could be used in temperature measurements by optical methods.
optoelectronics, A2MX4 type crystals, incommensurate phases, non-linear phenomena, temperature sensors
Full paper (197kB): M&MS_2005_285.pdf
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PAWEŁ PAWLUS
Rzeszów University of Technology
Department of Manufacturing Technology and Production Organisation, Poland
e-mail: ppawlus@prz.rzeszow.pl
AN ANALYSIS OF SLOPE OF SURFACE TOPOGRAPHY
The fundamental aim of this paper is to assess various methods of surface topography slope calculations. Computer generated and measured 2-D profiles and 3-D surface topographies of random and asymmetric ordinate distributions were analysed. The paper examines the use of various differential formulae for the calculation of surface slope. The effect of measurement errors on random profile slope was analysed. Dependence among slope and other parameters, relation between average and rms slope as the measure of profile asymmetry were studied. Variation of profile slope was examined. Prediction of surface slope after 2 processes was performed. The errors of obtaining surface slope based on profile slopes in orthogonal directions were analysed based on computer generated and real surface topographies. The deviation between profile slopes in two orthogonal direction as the measure of anisotropy of honed cylinder surfaces was examined.
Keywords: surface topography, slope, measurement errors
Full paper (252kB): M&MS_2005_299.pdf
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ZBIGNIEW SZCZEŚNIAK
Kielce University of Technology
The Faculty of Electrical Engineering, Automatic Control and Computer Science, Poland
e-mail: Z.Szczesniak@tu.kielce.pl
METHOD OF PROCESSING ACCURACY ENHANCEMENT OF PHOTOELECTRIC POSITION TRANSDUCER SIGNALS
A method and the system for accuracy enhancement and motion direction discrimination of the photoelectric position transducer have been presented in the paper. In the system sinusoidal phase voltages, with the assumed phase shift equal to 36° have been generated. The voltages enable a frequency increment of 2.5 times in relation to basic signals from the transducer measurement bar. These two signals of increased frequency are rectangular, shifted mutually by 1/4 of a period, with the pulse-duty factor equal to 0.5. On the base of these signals it is possible to further increase the accuracy twofold, in the system of pulse counting and pulse sequence discrimination, with the use of the trigger method of its motion direction identification. Presented methods and systems make it possible to increase the transducer processing accuracy five times.
Keywords: motion direction discrimination, enhancement of photoelectric transducer accuracy
Full paper (197kB): M&MS_2005_315.pdf
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SANJAY YADAV, A. K. BANDYOPADHYAY
National Physical Laboratory
New Delhi - 110 012, India
e-mail: syadav@mail.nplindia.ernet.in
PROFICIENCY TESTING (PT) PROGRAM UNDER NABL IN THE PRESSURE RANGE
7- 70 MPA USING DIGITAL PRESSURE CALIBRATOR (DPC)
This paper describes the proficiency testing of the seven laboratories, accredited by National Accreditation Board for Testing and Calibration of Laboratories (NABL), India using a Digital Pressure Calibrator (DPC) [Model No. - H540/101, Sl. No.- MC808, make-DH-Budenberg, U.K.] as an artifact in the pressure range 70 bar to 700 bar (7 MPa to 70 MPa). The primary objective for organizing this proficiency testing (PT) is to assess the laboratory's technical competence to perform measurements and also fulfilling the requirement of ILAC/APLAC in regards to the compatibility of results submitted by these laboratories. National Physical Laboratory (NPLI), New Delhi, India has the responsibility of coordinating this programme and also acted as a reference laboratory.
The stability of the artifact was assessed by measurements made at NPLI before and after the circulation of the artifact. The comparison was carried out at 11 arbitrarily chosen pressure points i.e. 0.7 MPa, 14 MPa, 21 MPa, 28 MPa, 35 MPa, 42 MPa, 49 MPa, 56 MPa, 63 MPa and 70 MPa throughout the entire pressure range. Six measurements were performed at each eleven pressure points, three each in increasing and decreasing orders of pressures, respectively. Laboratories were advised to report the values of various parameters related to the artifact including the temperatures at which the measurements were made. As it was a digital gauge, all participating laboratories were requested to perform the measurement at a temperature sufficiently close to 23°C so that the standard uncertainty of the various coefficient of the artifact do not contribute to the overall measurement uncertainty. Data are analyzed as per ISO/IEC GUM document. The normalized error (En) values are estimated in the entire pressure range. These results are quite encouraging for the manufacturers and calibration laboratories that are facing a new environment after the WTO agreement.
Keywords: pressure, calibration, laboratory accreditation
Full paper (266kB): M&MS_2005_323.pdf
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