No. 1

No. 2

    No. 3            No. 4

  Theoretical Problems of Measurement

   Pages

M. Chvosteková, V. Witkovský:

Exact Likelihood Ratio Test for the Parameters of the Linear Regression Model with Normal Errors

Abstract: In this paper we present an exact likelihood ratio test (LRT) for testing the simple null hypothesis on all parameters of the linear regression model with normally distributed errors. In particular, we consider the simultaneous test for the regression parameters, β, and the error standard deviation, σ. The critical values of the LRT are presented for small sample sizes and the small number of explanatory variables for usual significance levels, α = 0.1, 0.05, and 0.01. The test is directly applicable for construction of the (1 − α)-confidence region for the parameters (β,σ) and the simultaneous tolerance intervals for future observations in linear regression models. For comparison, the suggested method for construction of the tolerance factors of the symmetric (1 − γ)-content simultaneous (1 − α)-tolerance intervals is illustrated by a simple numerical example.

Keywords:  linear regression model; exact likelihood ratio test; simultaneous tolerance intervals; confidence-set approach

F. Rublík:

Critical Values for Testing Location-Scale Hypothesis

Abstract: The exact critical points for selected sample sizes and significance levels are tabulated for the two-sample test statistic which is a combination of the Wilcoxon and the Mood test statistic. This statistic serves for testing the null hypothesis that two sampled populations have the same location and scale parameters.

Keywords:  distribution-free rank test; combination of rank statistics; small sample sizes; location-scale hypothesis

  Measurement of Physical Quantities

K. Meiners-Hagen, R. Schödel, F. Pollinger, A. Abou-Zeid:

Multi-Wavelength Interferometry for Length Measurements Using Diode Lasers

Abstract: This paper describes the principle of precise length measurements using multi-wavelength interferometry. Three different examples are given in order to demonstrate PTB’s ability in this field: 1) Measurements of absolute distances up to 10 m performed by combination of the variable wavelength interferometry with fixed wavelength interferometry using two wavelengths simultaneously, 2) a three-wavelength diode laser interferometer for precision measurements of surface profiles (< 100 µm) and 3) PTB’s Precision Interferometer for length measurements of prismatic bodies, e.g. gauge blocks, using three wavelengths. The setup and principle of measurements and some results are presented and discussed in each case.

Keywords:  interferometry, diode laser, length measurement, long distance, surface profile, gauge blocks

J. Přibil, B. Zaťko, I. Frollo, F. Dubecký, P. Ščepko, J. Mudroň:

Quantum Imaging X–ray CT Systems Based on GaAs Radiation Detectors Using Perspective Imaging Reconstruction Techniques

Abstract: The work presents two generations of developed portable quantum X–CT mini–systems which utilize monolithic semi–insulating GaAs detectors. This contribution describes the present status of the assembling of the new portable X–ray CT mini system. Developed modification of the X–ray image reconstruction based on perspective imaging techniques has been experimentally verified on testing phantoms and practically implemented for processing images of real test objects. Performed measurement of the performance of the SI GaAs detectors and the integral spectra of ASIC DX64 readout chips are also mentioned.

Keywords:  X–ray imaging, single photon counting detector, image reconstruction

 No. 2

  Theoretical Problems of Measurement

A. M. Khurshid:

On Size-Biased Negative Binomial Distribution and its Use in Zero-Truncated Cases

Abstract: A size-biased negative binomial distribution, a particular case of the weighted negative binomial distribution, taking the weights as the variate values has been defined. A Baye’s estimator of size-biased negative binomial distribution (SBNBD) has been obtained by using non-informative and gamma prior distributions.  Also comparison has been made of this estimator with the corresponding maximum likelihood estimator (MLE) with the help of R- Software.

Keywords: size-biased negative binomial distribution, Baye’s estimator, R- Software

Measurement in Biomedicine

A. Unakafov:

Analysis and Modeling of the Galvanic Skin Response Spontaneous Component in the context of Intelligent Biofeedback Systems Development

Abstract:The paper presents an approach to galvanic skin response (GSR) spontaneous component analysis and modeling. In the study a classification of biofeedback training methods is given, importance of intelligent methods development is shown. The INTENS method, which is perspective for intellectualization, is presented. An important problem of biofeedback training method intellectualization – estimation of the GSR spontaneous component – is solved in the main part of the work. Its main characteristics are described; results of GSR spontaneous component modeling are shown. Results of small research of an optimum material for GSR probes are presented.

Keywords: galvanic skin response, spontaneous reactions, biofeedback, skin conductivity measurement, intelligent, modeling

  Measurement of Physical Quantities

A. Jamshaid:

Astronavigation System as an Autonomous Enhancement Suite for a Strapdown Inertial Navigation System: An Evaluation

Abstract: The determination of spacecraft coordinates is embodied by a navigation solution with high degree of autonomy, high precision and reliability. The foremost requirement for the solution of this problem is a strapdown inertial navigation system (SINS), which is autonomous, reliable and jamming resistant, but at the same time, errors in SINS increase with time. Therefore, for the SINS error correction, astronavigation system (ANS) is used as an additional navaid. This paper considers the ANS as an enhancement source for the SINS and presents its theoretical and practical aspects. The typical ANS makes use of star-trackers which are expensive, complicated in their structure and demand a-priori definition and vigilant preparation of each onboard attitude fix. To make this system cost effective and simple, an advanced configuration employs a charge coupled device (CCD) based star sensor rigidly mounted on a strapdown inertial measurement unit (SIMU). Consequently, in this evaluation, the ANS makes use of CCD based star sensors. Simulation results are presented to demonstrate the validity of the method for improving the navigation reliability and performance.

Keywords:  astronavigation, inertial navigation, Kalman filter, spacecraft, star sensor

J. C. Lee, Y.J. Noh, Y. Arai, W. Gao, C.H. Park:

Precision Measurement of Cylinder Surface Profile on an Ultra-Precision Machine Tool

Abstract: This paper describes the measurement of the surface straightness profile of a cylinder workpiece on an ultra-precision machine tool which has a T-base design with a spindle, an X-slide and a Z-slide. The movement range of the X-slide is 220 mm and that of the Z-slide is 150 mm, which have roller bearings in common. Two capacitive sensors are employed to scan a cylinder workpiece mounted on the spindle along the Z-axis. The straightness error motion of the Z-slide is measured to be approximately 100 nm by the reversal method. The straightness profile of the cylinder workpiece is evaluated to be approximately 400 nm by separation of the motion error, simultaneously.

Keywords:  measurement, surface profile, error motion, straightness, machine tool, slide, reversal method

 No. 3

Measurement in Biomedicine

A. van Oosterom:

Measuring the T Wave of the Electrocardiogram; The How and Why

Abstract: The genesis of the T wave of the electrocardiogram is discussed on the basis of a biophysical model, derived from the underlying electrophysiology. This model is used to scrutinize the commonly-assumed significance of the individual features of this waveform. As is shown, the last word is yet to be said about this topic.

Keywords:  T wave morphology; QT level abnormalities, timing apex, T wave duration

E. A. I. Aidu, V. G. Trunov, L. I. Titomir:

Biophysical Model for Beat-to-Beat Variations of Vectorcardiogram

Abstract: Linear deformation of the myocardium results in a linear transformation of orthogonal electrocardiosignals under the condition of topological invariability of the depolarization and repolarization processes in the myocardium. The relation between the linear transformations in the physical and functional spaces was found. Several practically important conclusions follow as a logical consequence of these statements. The parameters of linear transformations of the vectorcardiogram (eigenvectors, eigenvalues, rotation angles, determinants) may be used as indices of the heart position and haemodynamic changes.

Keywords:  vectorcardiogram, biophysical model, beat-to-beat alteration

  Measurement of Physical Quantities

J. Yang, Y. Arai, W. Gao:

Rapid Measurement of Involute Profiles for Scroll Compressors

Abstract: Scroll compressors are widely used in air conditioners, vacuum pumps and so on.  Rapid measurement of flank profile of a scroll compressor is important to improve the compression efficiency and decrease noises. A contact probe made of ruby was used for measurement of flank profile. The probe was moved by a linear slide along the X axis at a constant speed. The scroll workpiece was fixed on a precision rotary stage. The relationship between the stage rotational speed and the X axis moving speed complies with the Archimedean curve. The measurement data of the rapid measurement system were analyzed and measurement errors were removed by compensation of the offset between the coordinates of the rotary stage center and those of workpiece center. The measurement results were compared with those measured by a commercial coordinate measuring machine (CMM). The measurement time for the involute profile of the scroll is shortened to 153 seconds by the developed  rapid measurement system from the 10 minutes measurement time by the CMM while the measurement accuracy is kept the same.

Keywords:   scroll profile, error separation, involutes profile, scroll compressor, rapid measurement

Z. Jankauskas, V. Kvedaras, R. Gaivenis:

The Magnetoplasmic Measurements of the Carrier Density in Many-Component Solid State Plasma

Abstract: Many semiconductor materials manufactured by help of nanotechnology have charge carriers of different type and mobility. Already existing carrier density and mobility measurement methods are not accurate enough for the case of several carrier components. The use of  magnetoplasmic waves provides a simple and the most precise way to determine the density and mobility of each type of the carriers (electrons and/or holes). Magnetoplasmic waves may be excited in semiconductors when the strong magnetic field H is applied. The semiconductor sample becomes partially transparent under these conditions. In the case of magnetoplasmic resonance within each of the carrier groups, the transparency coefficient has a maximum. For fixed values H and excitation frequency w the density and mobility of every carrier type can be found. Dispersion relation for two types of charge carriers is obtained and resonance curves are calculated.

Keywords:  magnetic measurement, imaging, magnetic susceptibility, helicons, calculation, microwave frequencies

C. E. Nanjundappa,   I. S. Shivakumara, K. Srikumar:

Effect of MFD Viscosity on the Onset of Ferromagnetic Fluid Layer Heated from Below and Cooled from Above with Constant Heat Flux

Abstract: The effect of magnetic field dependent (MFD) viscosity on the onset of convection in a ferromagnetic fluid layer heated from below and cooled from above in the presence of vertical magnetic field is investigated theoretically. The bounding surfaces are considered to be either rigid-ferromagnetic or stress free with constant heat flux conditions. The resulting eigenvalue problem is solved using the Galerkin technique and also by regular perturbation technique. It is found that increase in MFD viscosity and decrease in magnetic number is to delay the onset of ferroconvection, while the nonlinearity of fluid magnetization has no influence on the stability of the system.

Keywords:  ferromagnetic fluid, constant heat flux, Galerkin technique, MFD viscosity

L. Laurinavičius:

Protection of HF Transmitters from Reflection Failure by Help of Semiconductor Isolators

Abstract: The fundamental problem of the transmitters protection against microwave energy reflections from aircraft antenna is discussed. The paper presents some applications of active and passive isolators and circulators as a tool for reflections protection. It has been stated that electrical properties of ferrite isolators and circulators grow worse at lower operational frequencies (below 50 MHz) and temperatures (cryogenic). Semiconductor magnetoplasma exhibits gyrotropic effects similar to those of magnetized ferrites and can solve the problem non-reciprocity in the HF range from 3 to 30 MHz, which is important for HF communication. The semiconductor device realization, optimal parameters, and operational temperature range, based on minimum forward loss α and maximum reverse attenuation β, were chosen. Major electromagnetic parameters of semiconductor isolators were determined.

Keywords:  protection, helicon, high frequency, magnetic field, non-reciprocity, semiconductor isolator, temperature stability

 No. 4

  Theoretical Problems of Measurement

M. Kamenský, K. Kováč:

Iterative Method and Dithering with Averaging used for Correction of ADC Error

Abstract: Additive iterative method in combination with averaging of dithered samples is designed for self-correction of ADC linearity error in the paper. Iterative method is one of the automated error correction techniques. Dithering is a special tool for quantizer performance enhancement. Dither theory for Gaussian noise and averaging has been used for exhibition of method abilities in ADC characteristic improvement.

Keywords: ADC error correction, iterative correction method, dithering

G. Wimmer, K. Karovič:

Interval Estimators of the Centre and Width of a Two-Dimensional Microstructure

Abstract: In metrology it is used to estimate the stipulated quantity as a mean and its uncertainty. This procedure is legitimate when the evaluated data are symmetrically distributed and the distribution is (at least approximately) known. But there exist many evaluating treatments in which the evaluated values are non-symmetrically distributed. In this case it is mathematically correct to use an interval estimator for the stipulated (measured) quantity i.e. to evaluate the (1-α)-confidence interval for the (true) stipulated (measured) quantity. This (random) interval covers with probability 1-α the (true) stipulated quantity. In the paper are presented interval estimators for some parameters of two-dimensional structures.

Keywords: confidence interval, evaluating of measured data, fitting by a regression line

Measurement in Biomedicine

M. G. Sowa, L. B. Mostaco-Guidolin, M. S.D. Smith, E. K. Kohlenberg,

A. Ridsdale, A. Stolow and A. C. T. Ko:

Nonlinear Optical Measurements of the Artery Wall: Parameters Related to the Progression of Atherosclerosis

Abstract: Nonlinear optical (NLO) microscopy is used to follow key structural and biochemical changes associated with the progression of atherosclerosis.  Arteries from WHHL-MI rabbits are examined using a 3 channel NLO microscope that can simultaneously monitor the coherent anti-stokes Raman scattered light (CARS), the two-photon excited fluorescence (TPEF) and the second harmonic generation (SHG) from a sample.  Distinct differences in the nonlinear optical signals are observed that correlate with the age of the vessel and the presence of atherosclerotic plaque.  These differences are attributed to the changing extracellular matrix and the increased lipid deposition associated with plaque development.  The capability of NLO to perform 3D sectioning in thick highly scattering vessels in order to visualize structural details of the artery wall and highlight vessel pathology is demonstrated.  These features make NLO a potentially valuable tool to help understand the progression of atherosclerosis.

Keywords: Nonlinear optical microscopy, coherent anti-Stokes Raman scattering, two photon excited fluorescence, second harmonic generation, atherosclerosis

J. Přibil, A. Přibilová:

Statistical Analysis of Spectral Properties and Prosodic Parameters of Emotional Speech

Abstract: The paper addresses reflection of microintonation and spectral properties in male and female acted emotional speech. Microintonation component of speech melody is analyzed regarding its spectral and statistical parameters. According to psychological research of emotional speech, different emotions are accompanied by different spectral noise. We control its amount by spectral flatness according to which the high frequency noise is mixed in voiced frames during cepstral speech synthesis. Our experiments are aimed at statistical analysis of cepstral coefficient values and ranges of spectral flatness in three emotions (joy, sadness, anger), and a neutral state for comparison. Calculated histograms of spectral flatness distribution are visually compared and modelled by Gamma probability distribution. Histograms of cepstral coefficient distribution are evaluated and compared using skewness and kurtosis. Achieved statistical results show good correlation comparing male and female voices for all emotional states portrayed by several Czech and Slovak professional actors.

Keywords: cepstral speech analysis, emotional speech, spectral flatness, microintonation

S. Ďaďo:

Tissue Morphology and Cell Impedance Based Biosensors for Toxicity Testing

Abstract: In vitro neurotoxicity testing and toxicity effect quantification plays an important role in many disciplines of biomedicine as an alternative to in vivo methods. The principle of the majority of in vitro methods corresponds to the basic concept of biosensors, i.e. measured quantity is by means of biological sensing element transformed to physical quantity easily measurable by electrical methods of measurement. Two types of biosensors suitable for neurotoxicity measurements are described in the paper. A common feature for both types is application of a living organism as biological sensing element. In the first type of biosensor the morphology of cell is evaluated using image processing methods known as videometry. In the second type of biosensors the electrical impedance of cells using an improved version of the ECIS (Electric Cell-substrate Impedance Sensing) method is a measure of toxicity effects. The results of experiments with biosensors using videometry and a proposal for improvements of ECIS based biosensors are included in the paper.

Keywords: neurotoxicity testing, biosensors, impedance of cells, ECIS method

  Measurement of Physical Quantities

J. Dřínovský, Z. Kejík:

Electromagnetic Shielding Efficiency Measurement of Composite Materials

Abstract:  This paper deals with the theoretical and practical aspects of the shielding efficiency measurements of construction composite materials. This contribution describes an alternative test method of these measurements by using the measurement circular flange. The measured results and parameters of coaxial test flange are also discussed. The measurement circular flange is described by measured scattering parameters in the frequency range from 9 kHz up to 1 GHz. The accuracy of the used shielding efficiency measurement method was checked by brass calibration ring. The suitability of the coaxial test setup was also checked by measurements on the EMC test chamber. This data was compared with the measured data on the real EMC chamber. The whole measurement of shielding efficiency was controlled by the program which runs on a personal computer. This program was created in the VEE Pro environment produced by © Agilent Technology.

Keywords:  shielding efficiency, composite materials, scattering parameters, measuring flange

 No. 5

Measurement in Biomedicine

K. Watanabe, Y. Taka, O. Fujiwara:

Cole-Cole Measurement of Dispersion Properties for Quality Evaluation of Red Wine

Abstract:  In order to evaluate the quality of red wine, measurement of the complex relative permittivity was conducted in the frequency range from 100 MHz to 40 GHz with a network analyzer. Results showed that the Cole-Cole plot of red wine consists of a semicircle at frequencies above 1 GHz and a straight line at frequencies below 1 GHz, which come from the dispersion properties for the water solution of alcohol and ingredients peculiar to red wine, respectively. Based on the Cole-Cole plots measured for seven kinds of red wines made from the same brand of Merlot in different production years, we estimated Debye dispersion parameters to reveal that the alcohol concentration and ingredient property can simultaneously be evaluated from the parameters for the semicircle and straight line, respectively.

Keywords:   Red wine, dispersion parameters, Cole-Cole plot, alcohol concentration, ingredients

J. Švehlíková, M. Kania, M. Turzová, E. Hebláková, M. Tyšler, R. Maniewski:

Identification of Ischemic Lesions Based on Difference Integral Maps, Comparison of Several ECG Intervals

Abstract:  Ischemic changes in small areas of myocardium can be detected from difference integral maps computed from body surface potentials measured on the same subject in situations with and without manifestation of ischemia. The proposed method for their detection is the inverse solution with 2 dipoles. Surface potentials were recorded at rest and during stress on 10 patients and 3 healthy subjects. Difference integral maps were computed for 4 intervals of integration of electrocardiographic signal (QRST, QRSU, STT and STU) and their properties and applicability as input data for inverse identification of ischemic lesions were compared. The results showed that better (more reliable) inverse solutions can be obtained from difference integral maps computed either from QRST or from STT interval of integration. The average correlation between these maps was 97%. The use of the end of U wave instead of the end of T wave for interval of integration did not improve the results.

Keywords:   Integral body surface potential maps, ischemic lesions, inverse solution to 2 dipoles

S. Haddab, M.Laghrouche:

Microcontroller -Based System for Electrogastrography Monitoring Through Wireless Transmission

Abstract:  Electrogastrography (EGG) is a non-invasive method for recording the electrical activity of the stomach. This paper presents a system designed for monitoring the EGG physiological variables of a patient outside the hospital environment. The signal acquisition is achieved by means of an ambulatory system carried by the patient and connected to him through skin electrodes. The acquired signal is transmitted via the Bluetooth to a mobile phone where the data are stored into the memory and then transferred via the GSM network to the processing and diagnostic unit in the hospital. EGG is usually contaminated by artefacts and other signals, which are sometimes difficult to remove. We have used a neural network method for motion artefacts removal and biological signal separation.

Keywords:  Electrogastrography, wireless, telemedicine

V. Juráš, P. Szomolányi, S. Gäbler, I. Frollo, S. Trattnig:

The Relationship between MR Parameters and Biomechanical Quantities of Loaded Human Articular Cartilage in Osteoarthritis: An In-Vitro Study

Abstract:  The aim of this study was to assess the changes in MRI parameters during applied load directly in MR scanner and correlate these changes with biomechanical parameters of human articular cartilage. Cartilage explants from patients who underwent total knee replacement were examined in the micro-imaging system in 3T scanner. Respective MRI parameters (T1 without- and T1 with contrast agent as a marker of proteoglycan content, T2 as a marker of collagen network anisotropy and ADC as a measure of diffusivity) were calculated in pre- and during compression state. Subsequently, these parameters were compared to the biomechanical properties of articular cartilage, instantaneous modulus (I), equilibrium modulus (Eq) and time of tissue relaxation (τ). Significant load-induced changes of T2 and ADC were recorded. High correlation between T1Gd and I (r = 0.6324), and between ADC and Eq (r = -0.4884) was found.

Keywords:  Articular cartilage, MRI, biomechanics, compression

K. Cimermanová:

Receiver Operating Characteristic Analysis for Classification Based on Various Prior Probabilities of Groups with an Application to Breath Analysis

Abstract:  In this paper we illustrate the influence of prior probabilities of diseases on diagnostic reasoning. For various prior probabilities of classified groups characterized by volatile organic compounds of breath profile, smokers and non-smokers, we constructed the ROC curve and the Youden index with related asymptotic pointwise confidence intervals.

Keywords:  Breath analysis, ROC analysis, confidence intervals, discriminant analysis, prior probability

 No. 6

Theoretical Problems of Measurement

Z. Domotor, V. Batitsky:                  Invited Article  

Measurement, Information Channels, and Discretization: Exploring the Links

Abstract:  The goal of this paper is to present a unified algebraic-analytic framework for (static and dynamic) deterministic measurement theory, which we find to be fully adequate in engineering and natural science applications. The starting point of this paradigm is the notion of a quantity algebra of a measured system and that of a measuring instrument, underlying the causal linkages in classical ‘system + instrument’ interactions. This approach is then further enriched by providing a superimposed data lattice of measurement outcomes, intended to handle the information flow from the measured system to its measurand’s designated instrument.
We argue that the language of Banach and von Neumann algebras is ideally suited for the treatment of quantities, encountered in theoretical and experimental science. These algebras and convex spaces of expectation functionals thereon together with information (co)channels between them provide a comprehensive information-theoretic framework for measurement theory. Concrete examples and applications to length and position measurements are also discussed and rigorously framed within the proposed quantity algebra and associated information channel paradigms. In modeling physical systems, investigators routinely rely on the assumption that state spaces and time domains form a continuum (locally homeomorphic to the real line or its Cartesian powers). But in sharp contrast, measurement and prediction outcomes pertaining to physical systems under consideration tend to be presented in terms of small discrete sets of rational numbers. We investigate this conceptual gap between theoretical and finitary data models from the perspectives of temporal, spatial and algebraic discretization schemes.
The principal innovation in our approach to classical measurement theory is the representation of interactive
instrument-based measurement processes in terms of channel-cochannel pairs constructed between dynamical quantity algebras of a target system and its measurand’s measuring instrument. 

Keywords:   Quantity algebra, measurement theory, instrument model, information channel, cochannel, discretization

Measurement in Biomedicine

J. Heller, J. R. Feldkamp:

Auto-Tuned Induction Coil Conductivity Sensor for In-Vivo Human Tissue Measurements          Part I

Abstract:  Auto-tuned induction coil technology, based upon phase-locked loop circuitry (PLL), was developed and shown to be an effective tool for in-vivo measurement of electrical conductivity of human tissues.  Because electrical contact is not required, several disadvantages of the electrode method for conductivity determination are avoided, such as electrode polarization and variable conductivity associated with the stratum corneum of the epidermis.  Fixed frequency excitation is supplied to a parallel tuned RLC circuit, or “sensor”, while bias applied to a varactor diode is automatically adjusted via PLL circuitry to maintain the RLC sensor at resonance.  Since resonant impedance of a coil positioned near a conductive object is known to be frequency dependent, such an arrangement permits precise calibration of the sensor against a set of standard Potassium Chloride solutions.  In our experiments, a two-layer spiral coil is used with upper and lower spiral arms staggered so as to reduce inter-winding coil capacitance.  Preliminary in-vivo testing was done on the forearms of a single male subject as a prelude to more extensive use in a clinical setting.  In that instance, electrical conductivity at the proximal volar forearm location was shown to depend on forearm elevation.  Clinical studies using our prototype, as well as further consideration of the “elevation effect”, are discussed in a companion paper. 

Keywords:  Induction coil, electrical conductivity, phase-locked-loop, human tissues, impedance, resonance

J. R. Feldkamp and J. Heller:

Effects of Extremity Elevation and Health Factors on Soft Tissue Electrical Conductivity          Part II

Abstract:  Two clinical studies were completed using an auto-tuned induction coil conductivity sensor (ICCS) to determine the effects of a variety of factors on the electrical conductivity of soft tissue.  In addition to fifteen “subject variables” such as blood pressure and others, we have specifically focused on considering the role of such factors as gender, age, BMI, smoking and elevation of extremities.  Measurements were made at seven sites on either side of the body for a total of fourteen.  Higher conductivities were obtained for women than men at all sites.  At five sites, where age was a significant factor, conductivity was found to decline with increased age.  Interestingly, smokers as a group tended to have reduced conductivity, suggesting that aging and smoking have similar effects on the microvasculature of soft tissue. Generally speaking, electrical conductivity is observed to increase in response to increased elevation at sites located on extremities.  Considering just healthy adults, a definite pattern of elevation-induced electrical conductivity displacement emerges when subjects are flagged according to high, low or moderate blood pressure.  We suggest that violations of this pattern may provide a method for identifying those individuals in an early stage of peripheral vascular disease.

Keywords:   Induction coil, electrical conductivity, soft tissue, extremity elevation, vascular disease

Measurement of Physical Quantities

I. Šimáček, P. Jurdák, J. Maňka, M. Škrátek:

Accuracy of the measurement with the second order axial gradiometer

Abstract:  Determining the accuracy of the measurement by using the second order axial gradiometer is presented. Output signals from the SQUID gradiometer system and calculated values of systematic errors depending on the shape and positioning of small cylindrical samples containing magnetized material are introduced. The measurement of the gradiometer detection characteristics and systematic error analysis were accomplished.

Keywords: Second order axial gradiometer, magnetic measurement, cylindrical sample, systematic error

M. Terada:

Application of ZigBee sensor network to data acquisition and monitoring

Abstract: A ZigBee sensor network for data acquisition and monitoring is presented in this paper.  It is configured using a commercially available ZigBee solution.  A ZigBee module is connected via a USB interface to a Microsoft Windows PC, which works as a base station in the sensor network.  Data collected by remote devices are sent to the base station PC, which is set as a data sink.  Each remote device is built of a commercially available ZigBee module product and a sensor.  The sensor is a thermocouple connected to a cold junction compensator amplifier.  The signal from the amplifier is input to an AD converter port on the ZigBee module.  Temperature data are transmitted according to the ZigBee protocol from the remote device to the data sink PC.  The data sampling rate is one sampling per second; the highest possible rate is four samplings per second.  The data are recorded in the hexadecimal number format by device control software, and the data file is stored in text format on the data sink PC.  Time-dependent data changes can be monitored using the macro function of spreadsheet software.  The system is considered a useful tool in the field of education, based on the results of trial use for measurement in an undergraduate laboratory class at a university.

Keywords: Sensor network, ZigBee protocol, temperature monitoring, automated data display, mechanical equivalent of heat

E. Konkov:

Ultrasonic Interferometer for High-Accuracy Linear Measurements

Abstract:  An application of ultrasonic interferometry is proposed and investigated as a new possible technique for high-accuracy linear and angular measurements. The basic principle of the proposed technique is the use of coherent running acoustic wave propagation along homogeneous solid waveguide in the capacity of linear measuring scale. The RMS sensitivity to the linear drift of 0.5 µm and RMS error of absolute measurement of  ± 12 µm over the distance up to one meter have been achieved experimentally. 

Keywords:  Ultrasound, interferometer, linear measurements, quartz fiber

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