IRENEUSZ JABŁOŃSKI, JANUSZ MROCZKA

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

INTERRUPTER VALVE KINEMATICS IN THE ISSUES OF PARAMETER ESTIMATION OF THE RESPIRATORY SYSTEM MODEL

The latest papers have been suggesting that the dynamics of transient state should be taken into account as the phenomena which occur in a respiratory system are interpreted (quantitatively and qualitatively). The influence of geometry and closure valve characteristic on the precision of obtained estimators of its parameters has been analyzed in the paper for the chosen model structure of the system. Results of simulation studies show that minimalization of mean-squared uncertainty d_MSE of the model elements estimation is obtained as valve closing (opening) time is shortened and its complete closure time is extended so that a linear increase in pressure P_ao is included.

Keywords: pulmonary mechanics, interrupter technique, indirect measurement, valve characteristics

Full paper (196kB): M&MS_2007_339.pdf

ADAM WOŹNIAK, MACIEJ KRETKOWSKI, RYSZARD JABŁOŃSKI

Warsaw University of Technology
Institute of Metrology and Measuring Systems
Poland, e-mail: wozniaka@mchtr.pw.edu.pl

MEASUREMENT METHOD OF SHAPE DEVIATION OF CYLINDRICAL MICRO-LENSES USING FOCUSED LASER BEAM AND REFERENCE AXIS

Constant progress in application of micro-lenses in many modern optical systems caused a continuous increase of the need to investigate methods of their measurement. A new method of measurement of shape deviation of such cylindrical micro-lens has been proposed. The concept is based on measurements of the distance between a reference and the lens surface in various directions. The reference points are established by the rotation axis of a precise rotary table. Detection of the surface of the measured object has been done using a focused laser beam moved by a high-resolution piezotranslator. In the paper we will show the results from our first measurements and we will discuss the advantages and disadvantages of our method as well as the method's accuracy.

Keywords: laser optical pickup, quadrant photodiode, astigmatic focusing error detection

Full paper (297kB): M&MS_2007_351.pdf

M. SZMAJDA¹, K. GÓRECKI¹, J. MROCZKA², J. BORKOWSKI<sup>2

1</sup>Opole University of Technology, Poland
e-mail: m.szmajda@po.opole.pl
²Wroclaw University of Technology, Poland
e-mail: janusz.mroczka@pwr.wroc.pl

THE ANTIALIASING FILTER PARAMETERS PROPOSITION FOR LABORATORY AND DOMESTIC EQUIPMENT APPLICATION OF POWER QUALITY MEASUREMENTS SYSTEMS

Digital signal processing exists in systems which perform the processing of power waveforms. All measuring devices that use digital signal processing and computing of its discrete spectrum should be equipped with an antialiasing filter which, unfortunately, creates errors in magnitude and phase spectrum responses. This paper discusses the spectrum distortion analysis of the power signals caused by antialiasing filter implementation in the analog-digital signal processing system paths. The paper is a continuation of problems included in [1]. On the basis of the same research methodology the article completes research carried out in [1] about a real input signal model. Thus, it has been possible to describe antialiasing filter parameters in power quality measurement systems for laboratory and domestic applications.

Keywords: Antialiasing filters, power quality, digital measurements, signal processing

Full paper (229kB): M&MS_2007_361.pdf

RADOSŁAW KŁOSIŃSKI

University of Zielona Góra
Institute of Electrical Metrology, Poland
e-mail: r.klosinski@ime.uz.zgora.pl

PERIODICALLY VARIABLE TWO-TERMINAL IMPEDANCE DESCRIPTION AND MEASURING METHODS

Keywords: periodically time-varying two-terminal, circular parametric operator, measurement methods

Full paper (1655kB): M&MS_2007_375.pdf

MACIEJ WAWRZYNIAK

Poznań University of Technology
Faculty of Electronics and Telecommunications
Poland, e-mail: mwawrz@et.put.poznan.pl

PROBE CAPACITANCE-DEPENDENT SYSTEMATIC ERROR IN I-V MEASUREMENTS OF NANOWIRES: ANALYSIS AND CORRECTION

We propose a method of eliminating the systematic error due to the capacitance of digital oscilloscope probes in the experimental setup used for tracing current-voltage (I-V) curves of nanowires with quantum point contact (QPC). Used in I-V measurements, a digital storage oscilloscope (DSO) allows a reduction of measurement time to microseconds. Such short measurement time, however, involves a sensible effect of transition states occurring in an experimental setup representing an RC circuit. We analyze the effect of probe capacitance on the signal reading and on the resulting I-V curves, and derive theoretical formulae for the probe capacitance-dependent systematic error on the basis of a model proposed for the discussed measurement method. The systematic error is evidenced by nonlinearity of the obtained current-voltage curve, its shift with respect to the origin of the coordinate system, and an extension of the measurement range. We propose a correction method based on the derived theoretical relations that allow to calculate the corrections to be applied. The presented results of I-V measurements of nanowires with QPC confirm the correctness of our model and the efiectiveness of the method proposed.

Keywords: nanotechnology, nanowires, quantum point contacts, conductance quantization, conductance measurements, current-voltage curves

Full paper (218kB): M&MS_2007_391.pdf

TOMASZ RADOMSKI, RYSZARD PEŁKA

Military University of Technology
Electronics Department
Warsaw, Poland, e-mail: tomasz.radomski@wel.wat.edu.pl

DIGITAL-TO-ANALOG CONVERSION USING DELTA-SIGMA MODULATORS IMPLEMENTED IN VIRTEX-4 FPGA DEVICES

This paper presents some selected architectures of delta-sigma modulators which are suitable for implementation of digital-to-analog converters (DACs) in modern FPGA devices. Simulation and implementation of simple architectures of first and second order of digital-to-analog converters in FPGA chip is described. Experimental tests have been performed using the evaluation board ML401 from Xilinx, based on the XC4VLX25 Virtex-4 chip. The quality of DACs has been measured and described by relevant power spectrum diagrams and differential linearity functions. Detailed comparison of DAC architectures is also given in terms of used resources and maximum operating frequency. It has been shown that carefully designed delta-sigma modulators implemented using modern FPGA technology are competitive to conventional integrated DACs. Consequently, multichannel DACs and ADCs of good quality can be designed within the FPGA chip. In this way, the idea of single-chip measurement system containing all essential parts as DACs, ADCs, CPU and digital I/O becomes an interesting alternative to the classical approach based on the multi-chip and/or ASIC technology.

Keywords: delta-sigma modulation, FPGA, digital-to-analog converter

Full paper (520kB): M&MS_2007_409.pdf

MIROSŁAW RUCKI

Poznan University of Technology
Division of Metrology and Measurement System
Institute of Mechanical Technology
Poland, e-mail: miroslaw.rucki@put.poznan.pl

STEP RESPONSE OF THE AIR GAUGE

In the paper, the results of investigations on the dynamical properties of air gauges have been presented. The basic parameter that underwent examinations has been the step response. It has been found that there is a difference between rising and falling signal response and that the whole pneumatic canal influences the behavior of the air gauge. The achieved response time values have been compared with the results of calculations based on the amplitude-phase characteristics.

Keywords: air gauging, step response, dynamical properties, dimensional measurement

Full paper (262kB): M&MS_2007_429.pdf

J. BEDNARCZYK, G. GŁUCH, E. WOJNAR, T. ZAŁUSKI

AGH-University of Science and Technology
Department of Process Control
Cracow, Poland, e-mail: bednarcz@agh.edu.pl

USING AN OPTICAL FIBRE SENSOR TO MEASURE DISPLACEMENT OF ELECTRODYNAMICALLY FORMED SHEET METAL

The paper discusses the use of reflective fibre-optic sensor for the purposes of measuring motion parameters of sheet metal formed at high speed, subject to percussive Lorentz forces extorted in a pulsed magnetic field.

Keywords: Optical fibre sensors, photoelectric displacement measurements

Full paper (2327kB): M&MS_2007_437.pdf

SANJAY YADAV

National Physical Laboratory
New Delhi
e-mail: syadav@mail.nplindia.ernet.in

CHARACTERIZATION OF DEAD WEIGHT TESTERS AND COMPUTATION OF ASSOCIATED UNCERTAINTIES: A CASE STUDY OF CONTEMPORARY TECHNIQUES

Estimation of uncertainty associated with pressure, measured by a dead weight tester is a key issue of recent times in pressure metrology. Though two different techniques have been used in the past yet there has been little uniformity in the way in which the measurement uncertainties of dead weight piston testers are evaluated and expressed. One of the techniques described in EAL document follows the universal approach based on ISO Guide and the relatively recent approach described in the National Accreditation Board of Laboratories (NABL-141) document presents a method for evaluating uncertainty in pressure measurement using dead weight testers through statistical analysis and error evaluated through linear curve fitting. This method is though in line with ISO Guide on the expression of uncertainty in measurement but differs from the traditional uncertainty measurement computations. The present paper describes a comparative study of these two different approaches through a case study carried out on an industrial dual range simple type dead weight tester. The paper also highlights some of the facts: how the new estimates affect pressure measurement and their commercial implementation and the benefits over traditional estimates.

Full paper (143kB): M&MS_2007_453.pdf