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CONTENTS
| E. Layer, K. Tomczyk - Determination of non-standard input signal maximizing the absolute error | 199 |
| 2. A. Cataliotti, V. Cosentino - A single-point approach based on IEEE 1459-2000 for the identification of detection of prevailing harmonic sources in distorted three phase power systems | 209 |
| 3. I. Jabłoński, J. Mroczka - A forward model of the respiratory system during airflow interruption | 219 |
| 4. M. Lisowski - Issues of volume resistivity measurement of flat dielectric specimens and evaluation on uncertainty of the measurement results by approximate method at confidence level of 0.95 | 233 |
| 5. E. Frączek, J. Mroczka - An accuracy analysis of small angle measurement using the Optical Vortex Interferometer | 249 |
| 6. M. Zieliński, M. Kowalski, R. Frankowski, D. Chaberski, S. Grzelak, L. Wydźgowski - Accumulated jitter measurement of standard clock oscillators | 259 |
| 7. J. Lal-Jadziak, S. Sienkowski - Variance of random signal mean square value digital estimator | 267 |
| 8. D. Gallo, C. Landi, M. Luiso - Compensation of Current Transformers by means of Field Programmable Gate Array | 279 |
| 9. M. Rucki, B. Barisic - Response time of the air gauges with different volumes of the measuring chambers | 289 |
| 10. K. Duda, D. Borkowski, A. Bień - Computation of the network harmonic impedance with Chirp-Z transform | 299 |
| 11. G. Śmigielski, D. Lewandowski, R.S. Dygdała, K. Stefański, W. Urbaniak - Water capsule flight - a theoretical analysis, experimental setup and experimental verification | 313 |
| 12. E. El-Din, M.M. Mekawy, K.M. Ali - Realization of Humidity Standard Facility Using Two- Pressure Humidity Generator and Humidity Chamber | 323 |
ABSTRACTS & FULL PAPERS
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DETERMINATION OF NON-STANDARD INPUT SIGNAL MAXIMIZING THE ABSOLUTE ERROR
Edward Layer, Krzysztof Tomczyk
Cracow University of Technology, Faculty of Electrical and Computer Engineering, Warszawska 24, 31-155 Kraków , Poland (pelayer@cyf-kr.edu.pl, + 48 12 628 2530, petomczy@cyf-kr.edu.pl)
Abstract
The paper presents a method and algorithm for determining input signals which maximize the absolute value of error. Being maximum, the values of these errors are valid for any dynamic signal which might occur at the input of a real system. In this way all the possible signals are taken into consideration at the same time. It should be stressed that these can be non-determined signals whose form cannot be predicted a priori. Two types of signals are taken into consideration: signals with a magnitude constraint and signals constrained in magnitude and rate of change. Solutions derived in the paper enable calculation of the absolute value of error by means of analytical formulae which give precise results and can be realised in a very short time.
Keywords: maximum dynamic error, dynamic measurement, signal constraints.
© 2009 Polish Academy of Sciences. All rights reserved
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A SINGLE-POINT APPROACH BASED ON IEEE 1459-2000 FOR THE IDENTIFICATION OF DETECTION OF PREVAILING HARMONIC SOURCES IN DISTORTED THREE PHASE POWER SYSTEMS
Antonio Cataliotti, Valentina Cosentino
University of Palermo, Department of Electrical, Electronic and Telecommunication Engineering,, Viale delle Scienze, 90128 Palermo, Italy (acataliotti@ieee.org, +39 091 6615270, cosentino@dieet.unipa.it)
Abstract
This paper deals with a novel single-point strategy for the detection of prevailing harmonic sources downstream or upstream the metering section in three-phase power systems. It is an enhancement of a previous strategy, already developed by the authors and it is based on the comparison of three non-active power quantities which are based on the IEEE Std. 1459-2000 approach. The method does not require any spectral analysis of voltages and currents because it is based only on the separation of the fundamental components from the harmonic content of voltage and current. In the paper, the effectiveness of the strategy is investigated by means of simulation tests which were carried out on a IEEE standard three-phase test power system used by other authors as a benchmark to test harmonic sources detection methods. The analysis is carried out considering also the presence of the measurement transducers.
Keywords: power measurements, harmonic distortion, reactive power, power quality, IEEE Std. 1459.
© 2009 Polish Academy of Sciences. All rights reserved
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A FORWARD MODEL OF THE RESPIRATORY SYSTEMDURING AIRFLOW INTERRUPTION
Ireneusz Jabłoński, Janusz Mroczka
Wroclaw University of Technology, Chair of Electronic and Photonic Metrology, Prusa 53/55, 50-317 Wrocław, Poland (ireneusz.jablonski@pwr.wroc.pl, +48 71 320 6329, janusz.mroczka@pwr.wroc.pl)
Abstract
The paper presents a methodology of complex electrical model formulation for the respiratory system during airflow interruption. Adequacy of both structural and parametric description to the real physiological system has been taken care of. Properties of the valve-transducer unit, upper airways, bronchial tree, lung tissue chest wall and abdomen have been noted in an equivalent description of the electrical circuit. The resulting analog, combining more than 180 parameters, gives the possibility to imitate conditions of normal breathing and airflow interruption. A qualitative verification of the model has been conducted in the time and frequency domain, based on reported numerous experimental findings. The proposed linear description of the respiratory system can be the source of synthetic data for a verification of the interrupter method and for the procedure of model reduction to its identifiable form.
Keywords: respiratory mechanics, interrupter technique, complex model.
© 2009 Polish Academy of Sciences. All rights reserved
Full paper (PDF, 341kB) |
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ISSUES OF VOLUME RESISTIVITY MEASUREMENT OF SOLID DIELECTRICS AND EVALUATION OF UNCERTAINTY OF RESULTS BY APPROXIMATE METHOD AT A CONFIDENCE LEVEL OF 0.95
Michał Lisowski
Wroclaw University of Technology, Institute of Electrical Engineering Fundamentals, Wybrzeże Wyspiańskiego 27,50-370 Wrocław, Poland, (michal.lisowski@pwr.wroc.pl)
Abstract
In the work, the issues of measurements of volume resistivity of solid dielectric made in a concentric three-electrode system have been described. The factors affecting the measurement results, especially the charge collected in the specimens in the result of their electrization and contact resistance between the electrode and specimen have been discussed. Special attention was paid to the effect of temperature and humidity. The methods of minimization of the factors were given. A simplified approach to the evaluation of uncertainty of measurement results of volume resistivity by approximate vector sum at a confidence level of 0.95 was presented.
Keywords: dielectric, measurement, volume resistivity, measurement uncertainty.
© 2009 Polish Academy of Sciences. All rights reserved
Full paper (PDF, 320kB)
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AN ACCURACY ANALYSIS OF SMALL ANGLE MEASUREMENT USING THE OPTICAL VORTEX INTERFEROMETER
Ewa Frączek, Janusz Mroczka
Wroclaw University of Technology, Chair of Electronic and Photonic Metrology, B. Prusa 53/55, 50-317 Wrocław, Poland (ewa.fraczek@pwr.wroc.pl, +71 320 6329, janusz.mroczka@pwr.wroc.pl)
Abstract
In recent years a lot of effort has been put into testing and improving the idea of a three-beam interferometer known as Optical Vortex Interferometer (OVI). Devices based on the idea of an OVI allow, among other things, measuring small rotation angles of the wave [1]. In this paper complex statistical analysis has been used for the results of the small-angle rotation wave measuring method. The authors of this paper claim that the presented analysis of data handling error in a new measurement method increases the accuracy of the measured angle by better choice of random triplets.
Keywords: optical vortex, small angle measurements, interferometry.
© 2009 Polish Academy of Sciences. All rights reserved
Full paper (PDF, 295kB)
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ACCUMULATED JITTER MEASUREMENT OF STANDARD CLOCK OSCILLATORS
Marek Zieliński, Marcin Kowalski, Robert Frankowski, Dariusz Chaberski, Sławomir Grzelak, Leszek Wydźgowski
Nicolaus Copernicus University, Institute of Physics, Department of Technical and Applied Physics, Grudziądzka 5, 87-100 Toruń, Poland(slawg@fizyka.umk.pl,+ 48 56 611 3324, marziel@fizyka.umk.pl , markow@fizyka.umk.pl, , daras@fizyka.umk.pl, robef@fizyka.umk.pl, lehhu@o2.pl)
Abstract
Long term instability of frequency and phase fluctuations of the clock signal are significant source of the measurement error in the precise time-interval measurement systems. In this paper the problem of clock signal instability, fluctuations caused by accumulated clock jitter and their influence on the precision of the time-interval measurement system implemented in the programmable CMOS FPGA devices are discussed. The presented method enables jitter characterization of the reference-clock. Moreover, the time-interval-error in the range up to several miliseconds can be easily and quickly calculated using only two parameters obtained during the calibration process. The described method can be applied in measurement instruments with a precise time-base.
Keywords: time-interval error, jitter, time-interval measuring module, phase fluctuations.
© 2009 Polish Academy of Sciences. All rights reserved
Full paper (PDF, 347kB)
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VARIANCE OF RANDOM SIGNAL MEAN SQUARE VALUE DIGITAL ESTIMATOR
Jadwiga Lal-Jadziak1), Sergiusz Sienkowski2)
1) Nicolaus Copernicus University, Institute of Physics, Grudziądzka 5, 87-100Toruń, Poland (jjadziak@fizyka.umk.pl, +48 56 611 2419)
2) University of Zielona Góra, Faculty of Electrical Engineering, Computer Science and Telecommunication, Institute of Electrical Metrology, Podgórna 50, 65-246 Zielona Góra ,Poland (s.sienkowski@ime.uz.zgora.pl)
Abstract
In the article, original relations enabling the estimation of the variance of a random signal mean square value digital estimator are derived. Three cases are considered: first when the estimator is determined from quantized samples; second, when it is additionally assumed that the conditions of Widrow's theorem are satisfied; and third, when the samples have not been quantized. The obtained relations can be used e.g. to determine uncertainty in precision measurements and to evaluate signal degradation in radio astronomy. As an example, the variance of the mean square value estimator of a random Gaussian signal for the three above-mentioned situations is analyzed. It has been observed that in the first and second cases, an increase in variance as well as in type A standard uncertainty takes place in comparison with the estimation based on unquantized samples. This increase diminishes along with an increase in the ratio of the signal rms value to the quantization step size.
Keywords: mean square value, digital estimator, characteristic function, estimator variance, type A uncertainty.
© 2009 Polish Academy of Sciences. All rights reserved
Full paper (PDF, 217kB)
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COMPENSATION OF CURRENT TRANSFORMERS BY MEANS OF FIELD PROGRAMMABLE GATE ARRAY
Daniele Gallo, Carmine Landi, Mario Luiso
Seconda Universita degli studi di Napoli, Dipartimento di Ingegneria dell'Informazione, Via Roma 29, 81031 Aversa (CE), Italy (mario.luiso@ unina2.it, +39 0815010375, daniele.gallo@unina2.it, carmine.landi@unina2.it)
Abstract
With the diffusion of non?linear and unbalanced loads, which often cause unacceptable quality level of energy, energy quality monitoring represents an increasing need. Analyzing conducted disturbances requires measuring instrumentation, and thus voltage and current transducers, with large bandwidth. Voltage and current transformers (CT) are the most often installed transducers in electrical power system and typically they are constructed to operate at industrial frequency 50/60 Hz, but it is clear that their substitution would require an unsustainable cost. Therefore in this paper a digital technique for the compensation of CT, based on field programmable gate array, is presented: it implements a digital filter with a frequency response equal to the inverse one of the CT. The compensated CT continues to be an analog device since the FPGA board is opportunely equipped with analog-to-digital and digital- to-analog converters.
Keywords: current transformer, compensation, digital filter, optimization, power quality.
© 2009 Polish Academy of Sciences. All rights reserved
Full paper (PDF, 237kB)
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RESPONSE TIME OF AIR GAUGES WITH DIFFERENT VOLUMES OF THE MEASURING CHAMBERS
Mirosław Rucki1), Branimir Barisic2)
1) Poznan University of Technology, Division of Metrology and Measurement System, Institute of Mechanical Technology, Piotrowo 3, 60-965 Poznań, Poland (miroslaw.rucki@put.poznan.pl, +48 61 665 3568)
2) University of Rijeka, Technical Faculty, Vukovarska 58, 51000 Rijeka , Croatia
Abstract
In the paper, investigations on the dynamic properties of air gauges are presented. The measurement of the amplitudes of back-pressure pk, dependent on the input signal angular frequency ω for the group of air gauges with various parameters has been performed. To evaluate the influence of the measuring chamber volume on the dynamical properties, a set of the model chambers with different dimensions has been prepared. The obtained results underwent a repeatability test in order to evaluate the uncertainty of time constant determination. Additionally, the impact of the feeding pipe was examined. Examinations of the time constant of typical back-pressure air gauge led to the conclusion that it depends also on the actual pressure and that it may differ between the beginning and the end of the measuring range.
Keywords: air gauging, frequency characteristics, dynamical properties, geometrical metrology.
© 2009 Polish Academy of Sciences. All rights reserved
Full paper (PDF, 297kB)
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COMPUTATION OF THE NETWORK HARMONIC IMPEDANCE WITH CHIRP-Z TRANSFORM
Krzysztof Duda, Dariusz Borkowski, Andrzej Bień
AGH University of Science and Technology, Department of Measurement and Instrumentation, Al. Mickiewicza 30, 30-059 Kraków, Poland (kduda@agh.edu.pl, +48 12 617 2841, borkows@agh.edu.pl, abien@agh.edu.pl)
Abstract
An innovative technique for power system harmonic impedance computation is presented in the paper. We present a brief introduction to harmonic impedance estimation problems as well as a detailed description of the proposed method. Frequency analysis with DFT is strongly affected by frequency leakage and picket fence errors. A number of methods was developed to reduce the impact of these phenomena including hardware solutions like PLL-based sampling synchronization, or software solutions like time- or frequency interpolation. Our work presented in the paper concerns new software-based method for reducing frequency leakage and picket fence errors and an application of this method of power system harmonic impedance estimation. The proposed method of harmonic impedance computation is based on Chirp-Z transform (CZT) instead of discrete Fourier transform (DFT). CZT enables arbitrary sampling of the frequency axis when computing spectra of discrete signals. We apply CZT to fundamental frequency estimation and for evaluating voltage and current frequency bins for higher harmonics. The spectral leakage is reduced by a standard Hanning window. The accuracy of the proposed method was verified by laboratory experiments and compared with the results of DFT-based computation. The proposed method is robust against non-synchronous sampling, thus it is dedicated for widely used data acquisition systems with a fixed sampling frequency. The proposed method is more accurate then DFT-based computations in case of voltage and current signals sampled at a fixed frequency. The advantages of the proposed method are evident for signals with off-nominal frequencies especially for higher harmonics.
Keywords: Chirp-Z transform, Fourier transform, impedance, harmonic analysis, power quality.
© 2009 Polish Academy of Sciences. All rights reserved
Full paper (PDF, 449kB)
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WATER CAPSULE FLIGHT - A THEORETICAL ANALYSIS, EXPERIMENTAL SETUP AND EXPERIMENTAL VERIFICATION
Grzegorz Śmigielski 2), Damian Lewandowski 1), Roman S. Dygdała 1,2), Krzysztof Stefański 3), Wiesław Urbaniak 2)
1) Pawel Wlodkowic University College in Plock, Al. Kilińskiego 12, 09-402 Płock, Poland (romdy1@onet.pl, damian_lew2@wp.pl)
2) The University of Economy, Garbary 2, 85-067 Bydgoszcz, Poland (gsmigielski@byd.pl)
3) Collegium Medicum UMK, Jagiellońska 13-15, 85-067 Bydgoszcz, Poland (stefan@fizyka.umk.pl, +48 52 585 3428)
Abstract
A bag filled with water is an excellent source of explosion-produced water spray which can be used for extinguishing large fires or for other purposes. The paper presents theoretical models of flight of a bag filled with water, dropped from an aircraft moving horizontally. Results of numerical computations based on this model are compared with results of measurements for the trajectory of a bag dropped from a helicopter. A description of the experimental and numerical setup for this experiment are also discussed.
Keywords: drag influenced flight, water aerosol production.
© 2009 Polish Academy of Sciences. All rights reserved
Full paper (PDF, 297kB)
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REALIZATION OF HUMIDITY STANDARD FACILITY USING TWO-PRESSURE HUMIDITY GENERATOR AND HUMIDITY CHAMBER
Essam El-Din, Mostafa Mahmoud Mekawy, Khaled Mohamed Ali
National Institute for Standards, Thermometry & Humidity Measurements Lab, Tersa St. P. O. Box: 136 Giza,12211, El-Haram, Egypt (essam70@yahoo.com, +2 0122867003, m_mekawy@yahoo.com, khalidali@nis.sci.eg)
Abstract
The realization of a dew/frost-point temperature scale is important for the calibration of hygrometers and dew/frost-point meters. Also, it was found that it is prime important for the National Institute for Standards-Egypt (NIS) to develop measurements of humidity field.
Experimental work used for realization of the dew/frost-point temperature scale, to calculate humidity measurements with high accuracy and to calculate the measurement uncertainty value of the dew-frost point. The dew-point temperature scale was realized using a two-pressure generator, humidity chamber, chilled mirror hygrometer and testo hygrometer. This work shows that the dew/frost-point temperature scale cover the range from -20 °C up to +70 °C with an uncertainty range from ± 0.52 °C to ± 1.7°C and covered the calibration requests from Egyptian industries.
We are looking forward to increase this range and decrease measurement the uncertainty value.
Keywords: dew/frost-point, humidity generator, humidity chamber, hygrometers, realization.
© 2009 Polish Academy of Sciences. All rights reserved
Full paper (PDF, 273kB)
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