POLISH ACADEMY OF SCIENCES

Division IV: Engineering Sciences

Committee on Metrology
and Scientific Instrumentation
VOLUME XI - NUMBER 4/2004 [previous] [next]

CONTENTS
Martin Burghoff - Biomagnetic recording as a tool to analyse bioelectric currents 307
Adam G. Polak, Dariusz Wysoczański, Janusz Mroczka - A transient state analysis of gas exchange in a human body 321
Igor Rubaszewski, Janusz Mroczka - Digital correction of nonlinear sensor dynamics by means of neural networks 333
Adam Żuchowski - On the methods of evaluation of Strejc's model parameters with use of measurement data representing system step response 345
Wojciech Toczek - Analog fault signature based on sigma-delta modulation and oscillation - test methodology 363
Józef Borkowski, Janusz Mroczka - Multifrequency signal analysis of the optic sensor signal in the LIDFT method 377
Antoni Gondek, Jerzy Króll - Metrological analysis of the averaging impact sensor flow meters based on the linear-logarithmic flow model 385
Barbara Juroszek, Karolina Maćkowiak - Karolczak, Ewa Przysiężna, Jan Stanisławski - Measurement of the electrical features of muscular tissue preserved in different conditions 397
Tomasz Barszcz - Proposal of new method for mechanical vibration measurement 409

ABSTRACTS

p. 307 contents

MARTIN BURGHOFF

Laboratory for Bioelectricity and Biomagnetism
Physikalisch-Technische Bundesanstalt, Berlin, Germany

BIOMAGNETIC RECORDING AS A TOOL TO ANALYSE BIOELECTRIC CURRENTS

Many processes in the human body are associated with bioelectric currents. Examples are activation of muscles, stimulus propagation in nerves and signal processing in the brain. These currents create magnetic fields which can be measured non-invasively. These biomagnetic fields are very weak and can be measured only with extremely sensitive magnetic sensors. Superconducting Quantum Interference Devices (SQUID) are able to record magnetic fields down to the fT-range and with a time resolution of 1 ms and better. To exclude external magnetic disturbances which are some orders larger than biomagnetic fields, magnetically shielded rooms consisting of mumetal layers can be used. The paper will give an introduction into the equipment necessary for biomagnetic recording as well as into the tools for signal processing to estimate the parameters of the current flowing in the body. The utility of the biomagnetic method will be demonstrated by the example of the detection of action currents propagating in peripheral nerves.

Keywords: biomagnetism, SQUID, electrical dipole, volume conductor
p. 321 contents

ADAM G. POLAK, DARIUSZ WYSOCZAŃSKI, JANUSZ MROCZKA

Wroclaw University of Technology
Chair of Electronic and Photonic Metrology

TRANSIENT STATE ANALYSIS OF GAS EXCHANGE IN A HUMAN BODY

A computational model of gas exchange in a human body was investigated in transient states to determine its sensitivity to the model parameters and, on this basis, to analyse the possibility of their indirect measurement. The results indicate that some of the parameters influence the outputs significantly in the transient state and that registration of four output signals increases their number. The precision of estimation is disturbed, however, by the correlation between the output sensitivities to the model parameters. This research should be prolonged to analyse measurement possibilities and accuracy in case of known diseases when additional information about the underlying pathological processes eliminates some of the disturbing correlations.

Keywords: gas exchange, computational model, transient state, sensitivity analysis, parameter selection
p. 333 contents

IGOR RUBASZEWSKI, JANUSZ MROCZKA

Wroclaw University of Technology
Chair of Electronic and Photonic Metrology

DIGITAL CORRECTION OF NONLINEAR SENSOR DYNAMICS BY MEANS OF NEURAL NETWORKS

The paper presents a simulation study concerning signal restoration from linear and nonlinear sensors by means of artificial neural networks. The influence of time-delay in the reconstructed signal on the restoration error has been investigated. This method is compared with direct restoration and linear regularization methods. Advantages of neural networks are shown. There is a potential for implemention of the presented method in microprocessor devices.

Keywords: signal restoration, artificial neural network
p. 345 contents

ADAM ŻUCHOWSKI

Technical University of Szczecin
Institute of Control Engineering

ON METHODS OF EVALUATION OF PARAMETERS OF STREJC'S MODEL WITH THE USE OF MEASUREMENT DATA REPRESENTING SYSTEM STEP RESPONSE

There are three groups of methods of identification of Strejc's model based on measurements of system step response. The methods assigned to the first group use the initial fragment of system step response. The methods of the second group process the co-ordinates of system step response inflexion point. The existence of a "common" point of step responses of Strejc's model is utilized by methods representing the third group. The methods assigned to the first group are not accurate if the system step response is deformed by disturbances. The disturbances affect substantially the evaluations of model time constant and its static gain. That is why methods of the first group are disregarded in this paper. The calculation formulae of methods assigned to the second group ought to be supplemented with a correction element making them more accurate. Furthermore, the proposed correction extends the area of applications of methods belonging to the second group. The methods of the third group seem to be very useful because they are relatively resistant to disturbances (due to possibility of filtering). If necessary, the primary Strejc's models yielded by methods of the third group can be transformed to the "new" forms. The considerations presented in the paper can be treated as a recapitulation of investigations carried out in the mentioned area. However, the known results have been enriched by important new elements.
p. 363 contents

WOJCIECH TOCZEK

Gdańsk University of Technology
Faculty of Electronics Telecommunication and Informatics

ANALOG FAULT SIGNATURE BASED ON SIGMA-DELTA MODULATION AND OSCILLATION-TEST METHODOLOGY

An analog fault signature for oscillation-based built-in self-test (OBIST) scheme is proposed. The signature uses sigma-delta modulation properties to obtain a digital code of the oscillator time-domain response. Fault signature in digital form can be easily interpreted by a purely digital circuit. The signature synthesiser consists of a peak detector, a sigma-delta modulator and an up/down counter. In the paper, features of sigma-delta signature based on impulse response are compared with one derived from the step response. Simulation results, on the example of the Meacham oscillator, reveal the superior diagnostic relevance of the impulse response signature. Concurrent use of signatures from both responses in order to increase the diagnostic sensitivity of the oscillation-test method is also possible.

Keywords: self-testing, oscillation-test method, sigma-delta fault signature
p. 377 contents

JÓZEF BORKOWSKI, JANUSZ MROCZKA

Wroclaw University of Technology
Chair of Electronic and Photonic Metrology

MULTIFREQUENCY SIGNAL ANALYSIS OF THE OPTIC SENSOR IN THE LIDFT METHOD

The possibility of applying the LIDFT method to determine frequencies, amplitudes and phases of the multifrequency signal obtained from an optic sensor has analyzed in the paper. The assumptions of the LIDFT method, basic equations, algorithm and obtained accuracy are presented.
p. 385 contents

ANTONI GONDEK, JERZY KRÓLL

Cracow University of Technology
Faculty of Mechanical Engineering

METROLOGICAL ANALYSIS OF AVERAGING IMPACT SENSOR FLOW METERS BASED ON THE LINEAR-LOGARITHMIC FLOW MODEL

In the article, metrological properties of impact sensor (Pitot tubes)used for flow measurement in duct of circular cross section are presented. Based on theoretical (line logarithmic) model velocity profile distribution coordinates of the velocity sensing ports in the probe are evaluated. Calculation of results formed the basis for evaluation of the calibration coeffiecient.
Flow measurement evaluated on the basis of an averaging Pitot tube allows precise measurement of the flow with an accuracy of ± 2% for the Re (Reynolds number) contained within the range {2,1×104 - 60×104}.

Keywords: flow meter, flow model, metrological analysis
p. 397 contents

B. JUROSZEK1, J. STANISLAWSKI2, K. MACKOWIAK-KAROLCZAK1, E. PRZYSIEZNA3

Wrocław University of Technology
1Faculty of Fundamental Problems of Technology,
2Faculty of Electronics, Institute of Telecommunication and Acoustics
3Wrocław University of Economics
The Faculty of Engineering and Economics, Management and Engineering of Foodstuffs Production

MEASUREMENT OF THE ELECTRICAL FEATURES OF MUSCULAR TISSUE STORED IN DIFFERENT CONDITIONS

The impedance of muscular tissue (turkey-bird breast muscles) was tested electrically with needle-electrodes at a frequency of 100 Hz. The meat was stored in different conditions of conservation and preservation. The material was divided into three groups: the first not packed, the second packed vacuously and the third conserved by using lactic acid and then vacuously packed. The meat presents considerable inhomogeneity which is observed in the impedance value in time and in frequency domains.The greatest changes between samples exist at lower frequencies. The impedance of meat depends strongly on the duration and method of its storage. The samples vacuously packed have the highest impedance in comparison with those not packed. The differences between particular days are up to 35 %. Lactic acid conservation influenced the value of impedance in relation to samples vacuously packed. The differences approaches 26 %.

Keywords: muscular tissue, storage conditions, electrical measurement
p. 409 contents

TOMASZ BARSZCZ

Akademia Górniczo-Hutnicza, Kraków, Polska

PROPOSAL OF A NEW METHOD OF MECHANICAL VIBRATION MEASUREMENT

Measurement of mechanical vibrations is used in many critical applications in various industries like: power generation, pulp & paper, chemical, oil etc. The measurement of vibrations in critical machinery is performed with the use of multi-channel systems which are sampling all channels simultaneously. The phase of signals carries also very important information and must be measured. Some important phenomena can be detected easier using order-tracking analysis, where the vibration signal is sampled at a constant number of samples per revolution rather than at constant frequency. Such sampling requires an advanced and costly triggering module. The paper proposes an equivalent system which is performing these actions in software algorithms running in real-time. The paper also presents errors introduced by such a technique.

Keywords: vibration, monitoring, synchronous sampling, resampling