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CONTENTS
| Jianbo Zhang, Paul Regtien, Maarten Korsten - Monitoring of dry sliding wear using fractal analysis | 111 |
| Andrzej Bień, Krzysztof Duda, Michał Szyper, Andrzej Wetula, Tomasz P. Zieliński, Andrzej Rozkrut - The new measure of low-frequency disturbances in power system | 121 |
| Grzegorz Kosobudzki, Zdzisław Nawrocki, Józef Nowak - Measure of electric reactive power | 131 |
| Adam Żuchowski - Dynamic measurement of the curve y(x) defined by parametric relations x(t), y(t) under random disturbances | 151 |
| Faten M. Megahed - Comparison between simple polynomials and an ITS-90 based reference functions of emf vs. temperature relation for high purity noble metal thermocouples | 165 |
| Anna Domańska - The impact of the randomization of the quantization error on the accuracy of measuring systems applying a digital measuring algorithm | 175 |
| Januariusz Górecki Krzysztof Kubas - Oscillatory mechanical flowmeter - theoretical analysis of operation | 183 |
| Bolesław Dobrowolski, Krzysztof Kręcisz - Numerical analysis of the influence of asymmetric deformation of the velocity field on metrological properties of the orifice | 195 |
| Michał Pawłowski, Paweł Kamiński, Roman Kozłowski, Stanisław Jankowski, Mariusz Wierzbowski - Intelligent measuring system for characterization of defect centres in semi-insulating materials by photoinduced transient spectroscopy | 207 |
ABSTRACTS & FULL PAPERS
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JIANBO ZHANG, PAUL REGTIEN, MAARTEN KORSTEN
University of Twente
Department of Electrical Engineering
7500 AE Enschede, The Netherlands
e-mail: jianbo.zhang@utwente.nl
MONITORING OF DRY SLIDING WEAR USING FRACTAL ANALYSIS
Reliable online monitoring of wear remains a challenge to tribology research as well as to the industry. This paper presents a new method for monitoring of dry sliding wear using digital imaging and fractal analysis. Fractal values, namely fractal dimension and intercept, computed from the power spectrum of the images of a wearing surface, are adopted as indicators of the dynamic wear process. Experimental results show that progressive changes of fractal values might reveal the wear status of the surface.
Keywords: dry sliding wear, fractal analysis
Full paper (488kB): M&MS_2005_111.pdf
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A. BIEŃ, K. DUDA, M. SZYPER, A. WETULA, T. .P ZIELIŃSKI, A. ROZKRUT
AGH University of Science and Technology, Kraków, Poland
e-mail: abien@uci.agh.edu.pl
THE NEW MEASURE OF LOW-FREQUENCY DISTURBANCES IN POWER SYSTEM
The paper presents new approach to voltage disturbances measurement in electric power network. It is assumed that analyzed disturbances are caused by simultaneous amplitude and phase modulation. Analytic signal is used for detection of amplitude and phase changes which are next measured as variation of a function. The proposed method is illustrated and verified by field experiment.
Keywords: analytical signal, fundamental component compensation, function variation, voltage fluctuation
Full paper (564kB): M&MS_2005_121.pdf
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GRZEGORZ KOSOBUDZKI, ZDZISŁAW NAWROCKI, JÓZEF NOWAK
Wrocław University of Technology
Institute of Electrical Machines, Drives and Metrology, Poland
e-mail: grzegorz.kosobudzki@pwr.wroc.pl
MEASURE OF ELECTRIC REACTIVE POWER
Generated electric power can either be dissipated or occur in the form of an electric field and a magnetic field. By replacing the voltage in the well-known equation for dissipated power (energy) with its derivative (a function orthogonal to the voltage) the average electric and magnetic field power exchanged between an electrical object and the rest of the closed electric power system was obtained. The measure of the (reactive) power is the surface area of the closed loop, which the object's characteristic forms in current-voltage coordinates.
Keywords: electric power, reactive power
Full paper (266kB): M&MS_2005_131.pdf
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ADAM ŻUCHOWSKI
Szczecin University of Technology
Institute of Control Engineering, Poland
e-mail: chlod@we.ps.pl
DYNAMIC MEASUREMENT OF THE CURVE y(x) DEFINED BY PARAMETRIC RELATIONS x(t), y(t) UNDER RANDOM DISTURBANCES
Analog XY-recorders constructed as servomechanisms with sliding motion have been practically out of use for some time. Drawing the curve y(x) defined by parametric relations xz(t), yz(t) under additive, random disturbances is done by using measuring sensors with negligible dynamic properties, A/D converter card, computer and a printer, with a different time scale and with elimination of the influence of the dynamics of these devices . The influence of disturbances can be significantly lowered either by using special filters before storing the data in computer memory or by suitable processing of the data already stored in the computer memory. In the first case we have to choose an appropriate filter type and its time scale factor T, and in the second case - an appropriate processing mode in order to get the resulting curve Y(X) as close as possible to the theoretical curve y(x). Both techniques provide different possibilities and create different problems which require separate considerations.
Keywords: measurement of the curve y(x), disturbance filtration, signal processing
Full paper (252kB): M&MS_2005_151.pdf
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FATEN MAHMOUD MEGAHED
National Institute for Standards
Thermometry Department
Tersa St. El- Haram, Giza 12211, Egypt
e-mail: yasserabdelfatah@yahoo.com
COMPARISON BETWEEN SIMPLE POLYNOMIALS AND AN ITS-90 BASED REFERENCE FUNCTIONS OF EMF VS. TEMPERATURE RELATION FOR HIGH PURITY NOBLE METAL THERMOCOUPLES
Emf versus temperature reference polynomial functions covering the temperature range from 100° C up to 960° C have been developed for three types of noble metal thermocouples, which are Pt-10%Rh/Pt, Au/Pt and Pt/Pd. Our functions are compared to the reference functions available in the literature. The thermocouples were fabricated and annealed for stabilization at 962° C for 300 hours before calibrations. After stabilization they were calibrated by comparison with Standard Platinum Resistance Thermometer (SPRT) in the temperature range from 100° C to 450° C and by comparison with a High temperature Standard Platinum Resistance Thermometer (HSPRT) in the temperature range from 450° C up to 950° C. The error of fit was evaluated and discussed.
Keywords: noble metal thermocouples, reference function, comparison calibration
Full paper (184kB): M&MS_2005_165.pdf
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ANNA DOMAŃSKA
Poznan University of Technology
Institute of Electronics and Telecommunications, Poland
e-mail: domanska@et.put.poznan.pl
THE IMPACT OF THE RANDOMIZATION OF THE QUANTIZATION ERROR ON THE ACCURACY OF MEASURING SYSTEMS APPLYING A DIGITAL MEASURING ALGORITHM
In measuring systems applying a digital measuring algorithm, the measurement process is divided into two stages: Stage 1 consists in the acquisition and storage of the system's input data, based on which the value of the measurand is estimated in stage 2. The uncertainty of the stored data is translated into the uncertainty of the result of the estimation, i.e. of the result of the measurement. When analog-digital conversion with a dither signal is applied in the data acquisition system (DAQ), the quantization error is modified and the uncertainty is reduced. The present paper discusses the mechanism of the modification of the quantization error and describes the characteristics of the uncertainty of a DAQ system applying a-d conversion with a dither signal.
Keywords: a-d conversion, dither, quantization error, uncertainty
Full paper (163kB): M&MS_2005_175.pdf
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JANUARIUSZ GÓRECKI, KRZYSZTOF KUBAS
Wrocław University of Technolog
Institute of Heat Engineering and Fluid Mechanics, Poland
e-mail: Krzysztof.Kubas@pwr.wroc.pl
OSCILLATORY MECHANICAL FLOWMETER - THEORETICAL ANALYSIS OF OPERATION
The paper proposes a method consisting in theoretical description of the main forces and related moments acting on a flowmeter oscillator. The mathematical analysis carried out has led to an equation representing the oscillator movement wherein phenomena occurring when a viscid stream flows around a movable body are taken into consideration.
Keywords: stream mass, oscillatory flowmeter, movement equation
Full paper (292kB): M&MS_2005_183.pdf
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BOLESŁAW DOBROWOLSKI, KRZYSZTOF KRĘCISZ
Technical University of Opole, Poland
e-mail: bolo@po.opole.pl
NUMERICAL ANALYSYS OF THE INFLUENCE OF ASYMMETRIC DEFORMATION OF THE VELOCITY FIELD ON METROLOGICAL PROPERTIES OF THE ORIFICE
A change of the stream direction during a flow through a single elbow or their system causes asymmetric deformation of the velocity field. If two elbows are located in various planes, also a stream swirl can occur. The influence of these two phenomena on the accuracy of measurement of the fluid stream with orifices has been so far determined experimentally. In this paper theoretical considerations have been applied. Fluid motion has been described by the Reynolds set of equations closed with the k-ε model of turbulence. The three-dimensional set of equations has been solved for a fluid flow through the straight pipeline in the flow system with one or two elbows located in various planes. The tests were performed in order to estimate the influence of the velocity field upstream the orifice on the pressure distribution on the wall and the discharge coefficient for different distances of local obstacles from the orifice. The calculation results have been compared with the available experimental results.
Keywords: flow measurements, pipe orifice, asymmetric flow, measurement error
Full paper (498kB): M&MS_2005_195.pdf
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M. PAWŁOWSKI1,2, P. KAMIŃSKI1, R. KOZŁOWSKI1, S. JANKOWSKI3, M. WIERZBOWSKI2
1 Institute of Electronic Materials Technology, 01-919 Warsaw, Poland
2 Military University of Technology, 00?908 Warsaw 49, PO Box 50, Poland
3 Warsaw University of Technology, 00-665 Warsaw, Poland
e-mail: mpawlowski@itme.edu.pl
INTELLIGENT MEASURING SYSTEM FOR CHARACTERISATION OF DEFECT CENTRES IN SEMI-INSULATING MATERIALS BY PHOTOINDUCED TRANSIENT SPECTROSCOPY
An intelligent measurement system for the characterisation of defect centres in semi-insulating materials is presented. The system utilises two-dimensional analysis of the photocurrent transients digitally recorded in a broad range of temperatures. The spectral analysis is carried out by two independent methods: the two-dimensional correlation procedure and the procedure based on the inverse Laplace transformation algorithm. Parameters of a defect centre are determined using the neural network algorithm which is based on two hidden neurons in the form of two-dimensional sigmoid functions used to obtain a morphological match of the approximating function to the shape of the fold on the spectral surface. The system is shown to be a powerful tool for studies of defect structure of high-resistivity semiconductors.
Keywords: Photoinduced Transient Spectroscopy (PITS), neural network, computational intelligence, defect centres, semi-insulating materials
Full paper (951kB): M&MS_2005_207.pdf
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