ADAM G. POLAK, DARIUSZ WYSOCZAŃSKI, JANUSZ MROCZKA

Wroclaw University of Technology
Chair of Electronic and Photonic Metrology, Poland
e-mail: janusz.mroczka@pwr.wroc.pl

A MULTI-METHOD APPROACH TO MEASUREMENT OF RESPIRATORY SYSTEM MECHANICS

A multi-method system developed for complex investigations of lung mechanics is described. The system includes complementary measurement techniques such as forced oscillations, interrupter technique, methods for measurement of pulmonary mechanics during artificial ventilation and spirometry. These techniques are completed by computational models enabling an analysis of the relation between the lung structure, function, pathology and measurement results. This set-up is a first step towards a new-quality approach to research into the respiratory system via multi-method fusion.

Keywords: pulmonary mechanics, forced oscillations, mechanical ventilation, interrupter technique, spirometry, computational model, multi-method fusion

Full paper (267kB): M&MS_2006_003.pdf

ANDRZEJ MUCIEK¹⁾, FRANCO CABIATI<sup>2)

1)</sup> Wrocław University of Technology
Chair of Electronic and Fotonic Metrology, Poland
e-mail: amuciek@kmeif.pwr.wroc.pl
²⁾ Istituto Elettrotecnico Nazionale Galileo Ferraris Torino, Italy

ANALYSIS OF A THREE-VOLTMETER MEASUREMENT METHOD DESIGNED FOR LOW-FREQUENCY IMPEDANCE COMPARISONS

The principle of the three voltmeter method designed for precise impedance comparison is presented. Generalization of the classical approach is proposed and analysed. Formulas for impedance parameters determination are derived and measurement uncertainty analysed for various kinds of comparisons, and next optimal measurement conditions specified. Important voltmeter parameters, such as random error and non-linearity error, are experimentally investigated. The presented results show that by using the method and commercially available apparatus it is possible to compare two impedances with a relative uncertainty of (1-5)×10^-6 in the low frequency range.

Keywords: impedance measurements, impedance standards, voltage measurement, impedance comparison

Full paper (238kB): M&MS_2006_019.pdf

G.L. PANKANIN, J. BERLINSKI, R. CHMIELEWSKI

Warsaw University of Technology
Institute of Electronic Systems, Poland
e-mail: g.pankanin@ise.pw.edu.pl

SIMULATION OF KARMAN VORTEX STREET DEVELOPMENT USING A NEW MODEL

The article is devoted to the simulation of the Karman vortex street using an analytical model. The model has been described in detail in [1]. Fundamental quantities like velocity driving the vortex, vortex rotation and vortex rotation energy have been simulated. Also the influence of the fluid viscosity on the phenomena has been considered (analyzed). The results of the simulation have been compared with those obtained by application of other research methods. Considerable consistency has been reached.

Keywords: numerical modelling, simulation, Karman vortex street, vortex meter

Full paper (449kB): M&MS_2006_035.pdf

ZYGMUNT L. WARSZA

Polish Metrological Society
e-mail: ZLW@OP.pl

TWO-PARAMETER MEASUREMENTS AND SIGNAL CONDITIONING IN DOUBLE-CURRENT SUPPLY FOUR-TERMINAL RESISTANCE CIRCUITS

A new type of the four-terminal (4T) bridge circuit unconventionally supplied by current sources connected in parallel to opposite arms, named double current bridge (2J) is presented. It has two different outputs from both diagonals. Three variants of such circuit are proposed. Their output voltages are given as functions of arm resistance increments in absolute and in relative units . Signal conditioning formulas of the two-parameter (2D) measurement of these increments and also of two external variables differently influencing them are discussed in detail. First results of instrumentation designed experimentally using 2J bridge circuits are shortly presented. A summary and prospective applications of 2J bridge circuits in multivariable measurements are given. Literature is included.

Full paper (292kB): M&MS_2006_049.pdf

ALEKSANDER OLCZYK

Technical University of Lodz
Institute of Turbomachinery, Poland
e-mail: aolczyk@mail.p.lodz.pl

MEASUREMENTS OF UNSTEADY FLOW PARAMETERS IN PIPE-RECEIVER AND PIPE-TURBOCHARGER SYSTEMS

In the paper, the characteristic features of an unsteady flow in two systems: a high-volume pipe-receiver and a pipe-turbine are described. The tests were made under the conditions of a pulsating pipe supply in the range of frequencies 20-100 Hz. The following measurements of instantaneous values of unsteady flow parameters were made: pressure (piezoresistive transducers), temperature (Constant Current Thermometer) and velocity (Constant Temperature Anemometer). The applied measurement methods - owing to good dynamic properties of transducers - permitted us to gather relatively rich and complete information on flow phenomena in such systems. It was shown that the pipe-receiver system behaved as a resonator with a marked range of amplitude amplification and a distinct relationship between the resonance frequency and the pipe length. In this system, an effect of high pressure signal attenuation along the pipe and a reverse flow were observed as well. On the other hand, the pipe-turbine system is free of characteristic resonance frequencies and the pressure signal is transmitted along the pipe up to the turbine inlet section practically without any changes.

Keywords: pulsating flow, pressure, temperature and velocity measurements, resonance

Full paper (561kB): M&MS_2006_067.pdf

JOZEF VOJTKO

Technical University of Košice
Faculty of Electrical Engineering and Informatics
Department of Theory of Electrical Engineering and Measurement
042 00, Slovak Republic, e-mail: Jozef.Vojtko@tuke.sk

USING NEURAL NETWORKS FOR ERROR SUPPRESSION IN NONLINEAR SYSTEMS WITH HYSTERESIS

Some shortcomings of nonlinear systems with hysteresis are relatively big errors, e.g. linearity error, hysteresis error, etc. The paper deals with possible improvements in the methods of error suppression by using neural networks. Another aim of the paper is evaluation of measurement uncertainty. It reviews the procedures currently applied for measurement uncertainty calculation according to ISO Guide.

Keywords: measurement, sensor errors, error suppression, uncertainty, neural network

Full paper (1713kB): M&MS_2006_079.pdf

KRZYSZTOF TOMCZYK

Cracow University of Technology,
Faculty of Electrical and Computer Engineering, Poland
e-mail: petomczy@cyf-kr.edu.pl

APPLICATION OF GENETIC ALGORITHM TO MEASUREMENT SYSTEM CALIBRATION INTENDED FOR DYNAMIC MEASUREMENT

Keywords: maximum dynamic error, genetic algorithm

Full paper (247kB): M&MS_2006_093.pdf