No. 1

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  Measurement of Physical Quantities

   Pages

L. Angrisani, D. Capriglione, L. Ferrigno, G. Miele:

A New Digital Signal Processing Method for Spectrum Interference Monitoring

Abstract: Frequency spectrum is a limited shared resource, nowadays interested by an ever growing number of different applications. Generally, the companies providing such services pay to the governments the right of using a limited portion of the spectrum, consequently they would be assured that the licensed radio spectrum resource is not interested by significant external interferences. At the same time, they have to guarantee that their devices make an efficient use of the spectrum and meet the electromagnetic compatibility regulations. Therefore the competent authorities are called to control the access to the spectrum adopting suitable management and monitoring policies, as well as the manufacturers have to periodically verify the correct working of their apparatuses. Several measurement solutions are present on the market. They generally refer to real-time spectrum analyzers and measurement receivers. Both of them are characterized by good metrological accuracies but show costs, dimensions and weights that make no possible a use “on the field”. The paper presents a first step in realizing a digital signal processing based measurement instrument able to suitably accomplish for the above mentioned needs. In particular the attention has been given to the DSP based measurement section of the instrument. To these aims an innovative measurement method for spectrum monitoring and management is proposed in this paper. It performs an efficient sequential analysis based on a sample by sample digital processing. Three main issues are in particular pursued: (i) measurement performance comparable to that exhibited by other methods proposed in literature; (ii) fast measurement time, (iii) easy implementation on cost-effective measurement hardware.

Keywords:  spectrum monitoring, spectrum management, spectrogram, digital signal processing, RF measurement

J. Maňka, A. Cigáň, J. Polovková, A. Koňakovský, A. Prnová:

Effects of Slight Non-Stoichiometry in Sm-Ba-Cu-O Systems on Superconducting Characteristics

Abstract: We studied the effects of slight Sm-Ba non-stoichiometry in Sm-Ba-Cu-O superconducting compounds on their transition, structural, and magnetic properties. Two series of single-phase samples of Sm1+xBa2-xCu3O7+δ and Sm1-xBa2+xCu3O7+δ with composition deviation from stoichiometry x from 0 to 0.1 were synthesized by the solid-state reaction method from Sm2O3, BaCO3 and CuO precursors and sintered at the temperature of ~ 1060 °C in flowing oxygen. All samples showed the values of Tc > 90 K and the volume density, ρ, 6.45 g cm-3 < ρ ≤ 6.73 g cm-3. The effect of the composite deviation of x on Tc, ∆Tc, and volume magnetization M was studied. For Sm1+xBa2-xCu3O7+δ compounds, optimal values of x were determined to maximize the width of the magnetization hysteresis at higher values of the applied magnetic field, corresponding mainly to the grain contribution. We also prepared the Sm1+xBa2Cu3O7+δ samples with x from 0 to 0.1 using the same processing conditions as in the case of A and B series. For the Sm1+xBa2 Cu3O7+δ samples, values of x = 0.02 - 0.03 optimize Tc, ∆Tc, Hp1 as well as M.

Keywords:  superconductors, Sm-123, cation non-stoichiometry, critical temperature, magnetization

M. Kamenský, K. Kováč:

Correction of ADC Errors by Additive Iterative Method with Dithering

Abstract: The iterative method could be used for automatic accuracy improvement of a measurement system. In its application for analog-to-digital converter (ADC) a quantization error represents a limitation for the correction process. Therefore, combination of correction methods is common for ADC error correction. Combination of the additive iterative method (AIM) with nonsubtractive dithering (ND) has been proposed for slow measurement based on ADC where errors could change in time. The principle of combination of both techniques is described in the paper. AIM is based on precise inverse element (IE). In the designed system the IE output signal is created by pulse width modulation and low-pass filtering. A technique similar to deterministic dithering is employed to achieve precise processing of signal from IE. Analysis of influence of stochastic dither upon the results of correction is performed with the aim to find optimal parameters of ND. Finally, dependency of the root mean squared error and error dispersion on the measured value is drawn to show how AIM corrects the nonlinear deterministic error but slightly increases system noise.

Keywords: iterative correction, dithering, ADC error

M. A. Jusoh, Z. Abbas, J. Hassan, B. Z. Azmi, A. F. Ahmad:

A Simple Procedure to Determine Complex Permittivity of Moist Materials Using Standard Commercial Coaxial Sensor

Abstract: A simple procedure was developed to determine complex permittivity of moist materials for known percentage of moisture content at any frequency based using a standard commercial coaxial sensor. Polynomial fitting and Gaussian elimination method were applied to obtain a single equation of complex permittivity as a function of frequency and moisture content. The empirical equation was tested for new samples and was found to have mean error percentage of 5.14 % and 10.22 % for dielectric constant and loss factor, respectively, when compared to a commercial probe.

Keywords: open ended coaxial line, permittivity, maize, empirical model

A. Morando, M. Borsero, A. Sardi, G. Vizio:

Critical Aspects in Calibration of ESD Generators

Abstract: Electrostatic discharge (ESD) immunity tests are widely carried out in order to assess the immunity level of electrical and electronic equipment. ESD is a severe source of interference which can produce damage, upset or failures in any electronic system. A careful calibration procedure is required to assure that the ESD generator parameters fulfill the standard specifications. In this paper, the main critical aspects involved in the calibration measurement setup are dealt with and a simple modeling support is given. On the basis of the obtained results, some useful conclusions and practical suggestions are finally drawn.

Keywords: electrostatic discharges, calibration, electromagnetic compatibility, electromagnetic measurements, modeling, immunity.

P. Billik, M. Čaplovičová, J. Maňka, Ľ. Čaplovič, A. Cigáň, A. Koňakovský, R. Bystrický, A. Dvurečenskij:

Synthesis and Transport Properties of Nanostructured VO2 by Mechanochemical Processing

Abstract: The high-energy milling of the V2O5-Na2SO3 mixture in the range of 5 - 100 min leads to a synthesis of monoclinic VO2. The starting and minimum (at 220 °C) values of electric resistance R of the 100 min milled and pressed VO2-Na2SO4 mixture were 13.9 MΩ and 91.5 kΩ, respectively. The subsequent washing of the as-milled powder partially leads to the development of VO2 nanostructures with tube-like, sheet-like and rod-like morphology, besides VO2 (B) belt-like morphology, depending on the milling times.

Keywords:  nanostructures, chemical synthesis, transmission electron microscopy (TEM), electrical resistivity

 Theoretical Problems of Measurement

M. Černý, M. Rada:

On the Possibilistic Approach to Linear Regression with Rounded or Interval-Censored Data

Abstract:  Consider a linear regression model where some or all of the observations of the dependent variable have been either rounded or interval-censored and only the resulting interval is available. Given a linear estimator b of the vector of regression parameters, we consider its possibilistic generalization for the model with rounded/censored data, which is called the OLS-set in the special case b = Ordinary Least Squares. We derive a geometric characterization of the set: we show that it is a zonotope in the parameter space. We show that even for models with a small number of regression parameters and a small number of observations, the combinatorial complexity of the polyhedron can be high. We therefore derive simple bounds on the OLS-set. These bounds allow to quantify the worst-case impact of rounding/censoring on the estimator b . This approach is illustrated by an example. We also observe that the method can be used for quantification of the rounding/censoring effect in advance, before the experiment is made, and hence can provide information on the choice of measurement precision when the experiment is being planned.

Keywords:  linear regression; rounding; inexact data; interval-censored data

Measurement in Biomedicine

A. Phinyomark, C. Limsakul, P. Phukpattaranont:

Application of Wavelet Analysis in EMG Feature Extraction for Pattern Classification

Abstract:  Nowadays, analysis of electromyography (EMG) signal using wavelet transform is one of the most powerful signal processing tools. It is widely used in the EMG recognition system. In this study, we have investigated usefulness of extraction of the EMG features from multiple-level wavelet decomposition of the EMG signal. Different levels of various mother wavelets were used to obtain the useful resolution components from the EMG signal. Optimal EMG resolution component (sub-signal) was selected and then the reconstruction of the useful information signal was done. Noise and unwanted EMG parts were eliminated throughout this process. The estimated EMG signal that is an effective EMG part was extracted with the popular features, i.e. mean absolute value and root mean square, in order to improve quality of class separability. Two criteria used in the evaluation are the ratio of a Euclidean distance to a standard deviation and the scatter graph. The results show that only the EMG features extracted from reconstructed EMG signals of the first-level and the second-level detail coefficients yield the improvement of class separability in feature space. It will ensure that the result of pattern classification accuracy will be as high as possible. Optimal wavelet decomposition is obtained using the seventh order of Daubechies wavelet and the forth-level wavelet decomposition.

Keywords:  electromyography signal, EMG, feature extraction, wavelet transform, mean absolute value, root mean square, multi-resolution analysis

  Measurement of Physical Quantities

A. Kumar, H. Kumar:

Stability Studies of Torque Transducers     Short Communication

Abstract:  The present paper discusses the stability studies carried out on a small number of torque transducers over the years with capacities ranging from 10 Nm to 1000 Nm. The torque transducers have been calibrated using the torque standard machine based on the written standard calibration procedure. The study reveals that the uncertainty of measurement of torque transducers has been varying appreciably and it is more for lower range. Besides, the deviation from their average values has also been studied and found to be varying through the years.

Keywords:  torque transducer, torque standard machine, stability

X.h Liu, L Jin:

Effect of the Volume of Magneto-rheological Fluid on Shear Performance

Abstract:  As a kind of smart material, MR (magneto-rheological) fluid is dramatically influenced by the external magnetic field and can change from the liquid state to semi-solid state in several milliseconds. In this paper, the effect of different volume of MRF on its shear performance is proposed. A set of testing systems, including the plate-on-plate MRF shearing test rig, is built up to measure the relationship between the produced shear torque and the added volume of MRF in different current. The variation of magnetic flux density in the shear gap is measured by teslameter and simulated before and after MRF is added. The results validate the effect of volume on the shear torque experimentally.

Keywords:  shear performance, MR fluid, the volume, magnetic field

K.Vairamani, K. Arun Venkatesh, N. Mathivanan:

Design and Development of ZigBee Based Instantaneous Flat-plate Collector Efficiency Measurement System    Short Communication

Abstract:  Computing the efficiency of flat-plate collector is vital in solar thermal system testing. This paper presents the design of ZigBee enabled data acquisition system for instantaneous flat-plate collector efficiency calculation. It involves measurement of parameters like inlet and outlet fluid temperatures, ambient temperature and solar radiation intensity. The designed system has a base station and a sensor node. ZigBee wireless communication protocol is used for communication between the base station and the sensor node for wireless data acquisition. The wireless sensor node which is mounted over the collector plate includes the necessary sensors and associated signal-conditioners. An application program has been developed on LabVIEW platform for data acquisition, processing and analysis and is executed in base station PC. Instantaneous flat-plate collector efficiency is computed and reported.  

Keywords:  ZigBee, WSN, flat-plate collector, efficiency calculation, LabVIEW

L. Vojtíšek, I. Frollo, L. Valkovič, D. Gogola, V. Juráš:

Phased Array Receiving Coils for Low Field Lungs MRI: Design and Optimization

Abstract:  Recent techniques of radiofrequency (RF) probes and preamplifiers in Magnetic Resonance Imaging (MRI) developments almost reached the physical limits of signal to noise ratio (SNR). More improvements in speed accelerations of data acquisition are very difficult to achieve. One exception, called RF phased array coils, is recently being developed very progressively. The approach is conceptually similar to phased array used in radar techniques; hence it is usually called MRI phased array coils. It is necessary to ensure independence of the individual coil channels in the array by the coil and preamp decoupling and the coil geometry optimization to get maximum benefits from this technique. Thus, the qualitative design and method for optimization of geometric properties of the coil elements in phased arrays, with aim to increase SNR, minimize the G-factor and to limit noise correlation, are proposed in this paper. By the finite element method (FEM) simulations, we obtained the sensitivity maps and inductances of the coils. The introduced program primarily calculates the Sensitivity Encoding (SENSE) G- factor along with other parameters that can be derived from sensitivity maps. By the proposed optimization algorithm, the program is capable to calculate the optimal values of the geometric coil parameters in a relatively small number of iterations.

Keywords:  magnetic resonance imaging, phased array, field calculation, optimization

H. Kumar, A. Kumar, P. Yadav:

Improved Performance of 50 kN Dead Weight Force Machine using Automation as a Tool     Short Communication

Abstract:  Continuously growing technologies and increasing quality requirements have exerted thrust to the metrological institutes to maintain a high level of calibration and measurement capabilities. Force, being very vital in various engineering and non - engineering applications, is measured by force transducers. Deviations in the values observed and mentioned in the calibration certificate for force transducers may primarily be due to the creep, time loading effect and temperature effect if not properly compensated. Beside these factors, machine interaction, parasitic components etc. pertaining to the quality of the force standard machine used for calibration also contribute to the deviations. An attempt has been made by National Physical Laboratory, India (NPLI) to automate the 50 kN dead weight force machine to minimize the influence of factors other than the factors related to the machine itself. The calibration of force transducers is carried out as per the standard calibration procedure based on standard ISO 376-2004 using the automated 50 kN dead weight force machine (cmc ± 0.003% (k=2)) under similar conditions both in manual mode and automatic mode. The metrological characterization shows improved metrological results for the force transducers when the 50 kN dead weight force machine is used in automatic mode as compared to the manual mode.

Keywords:  dead weight force machine, automation, force

 Theoretical Problems of Measurement

D. Brodic:

Methodology for the Evaluation of the Algorithms for Text Line Segmentation Based on Extended Binary Classification

Abstract:  Text line segmentation represents the key element in the optical character recognition process. Hence, testing of text line segmentation algorithms has substantial relevance. All previously proposed testing methods deal mainly with text database as a template. They are used for testing as well as for the evaluation of the text segmentation algorithm. In this manuscript, methodology for the evaluation of the algorithm for text segmentation based on extended binary classification is proposed. It is established on the various multiline text samples linked with text segmentation. Their results are distributed according to binary classification. Final result is obtained by comparative analysis of cross linked data. At the end, its suitability for different types of scripts represents its main advantage.

 Keywords: document image processing, text line segmentation, testing methodology

H. Hegeduš, P. Mostarac, R. Malarić:

Comparison of RMS Value Measurement Algorithms of Non-coherent Sampled Signals

Abstract: Uncertainty and bias of RMS measurement of digitally non-coherent sampled signal is dependent on the algorithm used. This paper presents the new Averaging two subsets method for RMS value bias correction of non-coherent sampled signal. Methods for estimating RMS values in the time domain are also compared.

Keywords: RMS measurement methods, estimation algorithms, non-coherent sampling

Measurement in Biomedicine

O. Strbak, P. Kopcansky, I. Frollo:

Biogenic Magnetite in Humans and New Magnetic Resonance Hazard Questions

Abstract:  The widespread use of magnetic resonance (MR) techniques in clinical practice, and recent discovery of biogenic ferrimagnetic substances in human tissue, open new questions regarding health hazards and MR. Current studies are restricted just to the induction of Faraday currents and consequent thermal effects, or ‘inoffensive’ interaction with static magnetic field. We outlined that magnetic energies associated with interaction of ferrimagnetic particles and MR magnetic fields can be dangerous for sensitive tissues like the human brain is. To simulate the interaction mechanism we use our ‘Cube’ model approach, which allows more realistic calculation of the particle’s magnetic moments. Biogenic magnetite nanoparticles face during MR examination three principal fields: (i) main B0 field, (ii) gradient field, and (iii) B1 field. Interaction energy of biogenic magnetite nanoparticle with static magnetic field B0 exceeds the covalent bond energy 5 times for particles from 4 nm up to 150 nm. Translation energy in gradient field exceeds biochemical bond energy for particles bigger than 50 nm. Biochemical bond disruption and particle release to the tissue environment, in the presence of all MR fields, are the most critical points of this interaction. And together with relaxation processes after application of RF pulses, they make biogenic magnetite nanoparticles a potential MR health hazard issue.

Keywords:  biogenic magnetite, cube model, magnetic resonance, health hazard

J. Přibil, J. Horáček, P. Horák:

Two Methods of Mechanical Noise Reduction of Recorded Speech During Phonation in an MRI device

Abstract:  The paper presents two methods of noise reduction of speech signal recorded in an MRI device during phonation for the human vocal tract modelling. The applied approach of noise speech signal cleaning is based on cepstral speech analysis and synthesis because the noise is mainly produced by gradient coils, has a mechanical character, and can be processed in spectral domain. Our first noise reduction method is using real cepstrum limitation and clipping the “peaks” corresponding to the harmonic frequencies of mechanical noise. The second method is coming out from substation of the short-time spectra of two signals recorded withal: the first includes speech and noise, and the second consists of noise only. The resulting speech quality was compared by spectrogram and mean periodogram methods.

Keywords:   speech processing, noise reduction, NMR imaging

  Measurement of Physical Quantities

D. Kuhinek, I. Zorić, P. Hrženjak:

Development of Virtual Instrument for Uniaxial Compression Testing of Rock Samples

Abstract:  This paper presents the virtual instrument for measurement and determination of uniaxial compression strength and rock sample deformability. It analyzes properties and limitations of several implemented virtual instruments. Furthermore, comparison of implemented virtual instrument properties is presented.

Keywords: uniaxial strength, virtual instrument, measurement system properties

  Measurement of Physical Quantities

E.S. Senchenko, Yu.V. Chugui:

Shadow Inspection of 3D Objects in Partially Coherent Light

Abstract:  The peculiarities of 3D object image formation in a diffraction-limited system using quasi-monochromatic source with finite angular size are investigated. Algorithms for considerable increase in the accuracy of inspection of 3D objects by shadow optical method are proposed. These algorithms are based on high precision analytical determination of shift of shadow boundary image of thick object and on introduction of corrections depending on the object thickness and the optical system parameters. The theoretical results obtained have been experimentally verified.

Keywords: 3D image formation, shadow method, dimensional inspection, partially coherent source

D. P. Jena, R. Kumar:

Implementation of Wavelet Denoising and Image Morphology on Welding Image for Estimating HAZ and Welding Defects

Abstract:  In the current work, a filtering scheme for measurement of area and perimeter of heat affected zone (HAZ) in welding has been proposed along with identification of defects like porosity in the fusion zone. A filtering scheme based on wavelet filtering, edge detection and morphology has been designed and implemented on a welding image for this purpose. To see the effectiveness of the wavelet based proposed filtering scheme, SNR is calculated and compared with the filtered image processed without wavelet denoising. Experimental results revel that the SNR improves by 45-65% when wavelet filtering is introduced in the filtering scheme. Crisscrosses of the boundary of HAZ were observed and compared. The wavelet based proposed filtering scheme enhances the HAZ boundary smoothness by 12.5% in comparison to the filtering scheme without using wavelet denoising. In the limiting case, for poor quality image of weldment, the deviation in measurement of HAZ by manual and proposed scheme is within 10%. Error in manual evaluation significantly contributes in the above deviation as the HAZ on the base metal side in the raw image is diffused and difficult to measure accurately.

Keywords: wavelet, edge detection, morphology, thresholding, heat affected zone (HAZ),  porosity, signal to noise ratio

D. Kuhinek, I. Zorić, P. Hrženjak:

Measurement Uncertainty in Testing of Uniaxial Compressive Strength and Deformability of Rock Samples

Abstract:  This paper describes instrumental measurement uncertainties and their influence on the result obtained from determination of rock sample uniaxial compressive strength and deformability. The interdependence of uncertainty contribution is analyzed and guides for improving measurement uncertainty are given. The achieved uncertainties are compared to typical uncertainties in the determination of concrete and metallic material compressive strength and deformability.

Keywords: uniaxial compressive strength, deformability, rock samples, uncertainty

D. Patil, N. Das, A. Routray: 

Implementation of Fast-ICA: A Performance Based Comparison Between Floating Point and Fixed Point DSP Platform

Abstract:  The main focus of the paper is to bring out the differences in performance related issues of Fast-ICA algorithm associated with floating point and fixed point digital signal processing (DSP) platforms. The DSP platforms consisting of TMS320C6713 floating point processor and TMS320C6416 fixed point processor from Texas Instruments have been chosen for this purpose. To study the consistency of performance, the algorithm has been subjected to three different test cases comprising of a mixture of synthetic signals, a mixture of speech signals and a mixture of synthetic signals in presence of noise, respectively. The performance of the Fast-ICA algorithm on floating point and fixed point platform are compared on the basis of accuracy of separation and execution time. Experimental results show insignificant differences in the accuracy of separation and execution time obtained from fixed point processor when compared with those obtained from floating point processor. This clearly strengthens the feasibility issue concerning hardware realization of Fast-ICA on fixed point platform for specific applications.

Keywords: blind source separation, fast-ICA, floating point implementation, fixed point implementation

Measurement in Biomedicine

H. Rabbani:

Statistical Modeling of Low SNR Magnetic Resonance Images in Wavelet Domain Using Laplacian Prior and Two-Sided Rayleigh Noise for Visual Quality Improvement

Abstract: In this paper we introduce a new wavelet-based image denoising algorithm using maximum a posteriori (MAP) criterion. For this reason we propose Laplace distribution with local variance for clean image and two-sided Rayleigh model for noise in wavelet domain. The local Laplace probability density function (pdf) is able to simultaneously model the heavy-tailed nature of marginal distribution and intrascale dependency between spatial adjacent coefficients. Using local Laplace prior and two-sided Rayleigh noise, we derive a new shrinkage function for image denoising in the wavelet domain. We propose our new spatially adaptive wavelet-based image denoising algorithm for several low signal-to-noise ratio (SNR) magnetic resonance (MR) images and compare the results with other methods. The simulation results show that this algorithm is able to truly improve the visual quality of noisy MR images with very low computational cost. In case the input MR image is blurred, a blind deconvolution (BD) algorithm is necessary for visual quality improvement. Since BD techniques are usually sensitive to noise, in this paper we also apply a BD algorithm to an appropriate subband in the wavelet domain to eliminate the effect of noise in the BD procedure and to further improve visual quality.

Keywords: Wavelet transform, magnetic resonance images, blind deconvolution, maximum a posteriori estimator

R. Stojanović, D. Karadaglić, M. Mirković, D. Milošević:

A FPGA system for QRS complex detection based on Integer Wavelet Transform

Abstract:  Due to complexity of their mathematical computation, many QRS detectors are implemented in software and cannot operate in real time. The paper presents a real-time hardware based solution for this task.  To filter ECG signal and to extract QRS complex it employs the Integer Wavelet Transform. The system includes several components and is incorporated in a single FPGA chip what makes it suitable for direct embedding in medical instruments or wearable health care devices. It has sufficient accuracy (about 95%), showing remarkable noise immunity and low cost. Additionally, each system component is composed of several identical blocks/cells what makes the design highly generic. The capacity of today existing FPGAs allows even dozens of detectors to be placed in a single chip. After the theoretical introduction of wavelets and the review of their application in QRS detection, it will be shown how some basic wavelets can be optimized for easy hardware implementation. For this purpose the migration to the integer arithmetic and additional simplifications in calculations has to be done. Further, the system architecture will be presented with the demonstrations in both, software simulation and real testing. At the end, the working performances and preliminary results will be outlined and discussed. The same principle can be applied with other signals where the hardware implementation of wavelet transform can be of benefit.

Keywords: QRS detection, FPGA, Wavelet Transform.

  Measurement of Physical Quantities

K. Samu, A. Szakaly-Molnar:

Efficient Halogen Lamp Daylight Simulator for Color Vision Examination

Abstract:  Recently there has been a growing interest in the selection of product colors for design engineering purposes and for quality control. The selection is generally based on color samples and the quality control is carried out with specific measurement instruments. In low quantity production it is common to avoid instrumental color measurement using human control personnel instead. For such subjective color judgment it is necessary to have standardized illumination that is usually produced by high cost daylight simulator lamps. Our aim was to build a cost effective daylight simulator with halogen incandescent light sources that can match the parameters (CCT, CRI, MIvis and Illumination) of the similar but more expensive products.

Keywords: Halogen lamp application, daylight simulator, light booths, A and D65 simulator

X.h Liu, Z.m Fu, X.y Yao, F Li:

Performance of Magnetorheological Fluids Flowing Through Metal Foams

Abstract:  If magnetorheological (MR) fluids are stored in porous materials, when excited by the external magnetic field, MR fluid will be drawn out and produce MR effect, which could be used to solve the following problems of the MR damper, such as the seal, volume and the cost of MR fluid damper. In this paper, the effect of structure of metal foams on the performance of MR fluid is investigated; the relationship between the penetrability and the porosity of the metal foams is measured, the change of MR fluid performance flowing though the metal foams is obtained. It shows that, after flowing through metal foams, the change of performance of MR fluid is about 2.5%. Compared to the sponge, the porous metal foams have the obvious advantages in high porosity and rigidity, which provide a convenient and low-cost way to design the MR damper.

Keywords: Metal foams, penetrability, porosity, MR fluid

L. Laurinavičius:

Helicon Resonator based Strong Magnetic Field Sensor  

Abstract:  The effects of dimensional resonance of magnetoplasmic waves in semiconductors were investigated. It was demonstrated that these effects could be used to measure the strong magnetic fields. Possible ways to design contactless magnetic field sensors operating at room or at cryogenic temperature, such as that of liquid nitrogen are discussed. It has been shown that for strong field sensor a semiconductor material of high carrier mobility μ, density N and compact RF system for registration of dimensional resonance of magnetoplasmic waves in helicon resonator is needed.

Keywords: Semiconductors, magnetoplasmic waves, dimensional resonator, magnetic field, sensor

G. J. Stein, R. Chmúrny, V. Rosík:

Compact Vibration Measuring System for in-vehicle Applications

Abstract:  Low frequency vibrations occurring in ground transportation are of interest in research of the driver’s and the passenger’s comfort and in seating dynamics research. Piezoelectric accelerometers commonly used for vibration measurement are not well suited for the analysed frequency range. Hence, other sensors capable of measuring accelerations down to the sub-Hertz region have to be used. MEMS acceleration sensors are particularly suitable for such purposes. A compact measuring system employing two three-axial MEMS accelerometers interfaced via a USB data acquisition unit to a laptop was designed and constructed. The digitised data were then processed by scripts in Matlab® with the aim of analysing both the effect of vibration on a seated person and the dynamic properties of the seat. Preliminary results of a test run with a passenger automobile are presented.

Keywords: Vibration measurement, MEMS accelerometer, human comfort, driver’s seat properties

Measurement in Biomedicine

M. M. K. Najmie, K. Khalid, A. A Sidek, M. A. Jusoh:

Density and Ultrasonic Characterization of Oil Palm Trunk Infected by Ganoderma Boninense Disease

Abstract:  Oil palm trunks infected by Ganoderma boninense disease have been studied using density and ultrasonic characterizations. The ultrasonic characterizations have been performed using a commercial ultrasonic instrument at the frequency of 54 kHz.  The measurements have been done in 3 zones: inner zone, central zone and peripheral zone. It was found that the stem density of the oil palm infected by Ganoderma boninense disease was reduced by 50% in comparison to the original healthy trunk. From this effect the velocity of the ultrasonic wave propagated through the Longitudinal, Radial, and Tangential directions is lower for the trunk infected by Ganoderma boninense disease compared to a healthy trunk. For the 10 cm thickness of samples, the ultrasonic velocity for all transit directions was in range of 260 – 750 ms-1 for the infected sample, whereas for healthy samples was in the range of 460 – 900 ms-1. These results are very useful for the detection of the area which has been affected by the disease.

Keywords: Oil palm trunk, ultrasonic testing, elasticity constant, Ganoderma boninense

M. Dopsaj, J. Ivanović:

The Analysis of the Reliability and Factorial Validity in the Basic Characteristics of Isometric F-t curve of the Leg Extensors in Well Trained Serbian Males and Females

Abstract:  The aim of this research was to establish the reliability and factorial validity of different isometric basic characteristics of F-t curve related to leg extensors in well trained and healthy Serbian males and females. Sample consisted of 159 examinees. In order to assess characteristics of the F-t isometric leg extensor force, tensiometric probe and standardized "seating leg extension" test were used. The measurement range was defined by 4 variables regarding the contractile characteristics of the leg extensor isometric muscle force – 1) the level of the achieved maximal force – FmaxLegExtISO, 2) the indicator of basic (general) level of rate of force development – RFDBASICLegExtISO, 3) the time necessary to reach maximal force – tFmaxLegExtISO, 4) basic synergy index. The results showed a high statistical significance of p<0.001 in representability, generalizability and reliability for all the characteristics observed in both genders (Spearman-Brown r – 0.715 to 0.967 for males and 0.713 to 0.941 for females). As for the methodology aspect of testing, the factor analysis demonstrated the necessity of conducting at least three trials, choosing the best result from the two last trials.

Keywords: Isometric F-t curve, reliability, validity, leg extensors

Measurement in Biomedicine

M. D. Pereira, O. Postolache, P. S. Girão:

A Smart Measurement and Stimulation System to Analyze and Promote Non-Nutritive Sucking of Premature Babies

Abstract:  This paper presents a complete system that can be used to measure and to stimulate sucking abilities of premature babies. The system integrates measurement and stimulation capabilities that can be used separately or together. The sensing unit includes mainly a pressure sensor, a conditioning circuit and a microcontroller device. The stimulation unit includes a miniature and low-cost pneumatic pump, an electro-valve, and a conditioning circuit. The microcontroller is shared by both units. The system’s software includes a routine that is used to define the waveform parameters of the synthesized pressure signals, a wavelet based routine that is used to process measurement data and a software component to perform fault detection and diagnosis. The system capabilities include self-calibration and self-testing. Throughout the paper several implementation details and experimental results will be presented and discussed.

Keywords: Sucking pressure measurement, sucking stimulation, premature babies

D. Janusek, M. Kania, R. Zaczek, H. Zavala-Fernandez, A. Zbieć, G. Opolski, R. Maniewski:

Application of Wavelet Based Denoising for T-Wave Alternans Analysis in High Resolution ECG Maps

Abstract:  T-wave alternans (TWA) allows for identification of patients at an increased risk of ventricular arrhythmia. Stress test, which increases heart rate in controlled manner, is used for TWA measurement. However, the TWA detection and analysis are often disturbed by muscular interference. The evaluation of wavelet based denoising methods was performed to find optimal algorithm for TWA analysis. ECG signals recorded in twelve patients with cardiac disease were analyzed. In seven of them significant T-wave alternans magnitude was detected. The application of wavelet based denoising method in the pre-processing stage increases the T-wave alternans magnitude as well as the number of BSPM signals where TWA was detected.

Keywords: T-wave alternans, wavelet denoising, stress test, arrhythmia, sudden cardiac death

  Measurement of Physical Quantities

Z. Zhao, G. Wen:

Ball’s Motion Estimation Using a Line-Scan Camera

Abstract: An original method is proposed for estimating the position and velocity of a moving ball using a single line-scan camera. The method consists of two steps: firstly, the ball’s initial position and velocity are determined by several key points in the image, and secondly, these parameters are further refined by a model-based optimization algorithm. The algorithm achieves accurate parameter estimation by matching the projection contour of the real ball and that of the same size sphere model. Finally, the relevance and accuracy of the method are experimentally confirmed on synthetic and real images.

Keywords: Position, velocity, ball motion estimation, line-scan camera

V. Boháč, P. Dieška, V.Vretenár, V. Greif:

Model for Cuboid Shape Samples and its Analysis Used for Measurements of Thermophysical Properties of Sandstone

Abstract: A new model for the sample of square cross section with cuboid geometry including the effect of heat loss from the surface of the sample was tested using the theory of sensitivity coefficients. Theoretical calculation of model uncertainty and derived analytical formulas are presented. Results of the uncertainty analysis set out the range of experimental conditions under which the model is valid and the uncertainty of estimated parameters is low. Propagation of error for non-stochastic dynamic measurements based on the sensitivity coefficients shows limitations related to a range of model validity. The analysis improves the accuracy of measurements. The model was used for data evaluation of thermophysical parameters measured on the sandstone from the locality Pravčická brána. Evaluation procedure was tested on experimental data measured under different experimental conditions. In conclusion, the discussion of the experiment optimization is presented.

Keywords: Pulse transient method, sensitivity coefficient analysis, thermophysical properties

S. Sadana, S. Yadav, N. Jha, V. K. Gupta, R. Agarwal, A. K. Bandyopadhyay, T. K. Saxena:

A Computer Controlled Precision High Pressure Measuring System

Abstract: A microcontroller (AT89C51) based electronics has been designed and developed for high precision calibrator based on Digiquartz pressure transducer (DQPT) for the measurement of high hydrostatic pressure up to 275 MPa. The input signal from DQPT is converted into a square wave form and multiplied through frequency multiplier circuit over 10 times to input frequency. This input frequency is multiplied by a factor of ten using phased lock loop. Octal buffer is used to store the calculated frequency, which in turn is fed to microcontroller AT89C51 interfaced with a liquid crystal display for the display of frequency as well as corresponding pressure in user friendly units. The electronics developed is interfaced with a computer using RS232 for automatic data acquisition, computation and storage. The data is acquired by programming in Visual Basic 6.0. This system is interfaced with the PC to make it a computer controlled system. The system is capable of measuring the frequency up to 4 MHz with a resolution of 0.01 Hz and the pressure up to 275 MPa with a resolution of 0.001 MPa within measurement uncertainty of 0.025%. The details on the hardware of the pressure measuring system, associated electronics, software and calibration are discussed in this paper.

Keywords: Digital pressure calibrator, computer controlled pressure measurements, precision high pressure measuring system, pressure sensor, pressure transducer

M. A. Jusoh, Z. Abbas, K. Y. Lee, K.Y. You, A. M. Norimi:

Determination of Moisture Content in Mortar at Near Relaxation Frequency 17 GHz

Abstract:  The knowledge of moisture content in cement based material is important especially for the safety in field work. In this paper, a non-destructive and contactless free space method is used for measurement of moisture content in cement based materials (mortar) at microwave frequencies. The measurement system consists of a 17 GHz dielectric resonator oscillator (DRO) as a microwave source, a Power Meter as the detector, and a pair of lens horn antennas to transmit and receive the microwave signal. An empirical formula of moisture content was obtained by using a relationship between attenuation and moisture content. This model is best for prediction of moisture content greater than 2% with percentage mean error of 3%.

Keywords: Mortar, attenuation, moisture content, nondestructive technique (NDT), free space, transmission

N. Bharathi, P. Neelamegam:

FPGA Based Linear Heating System for Measurement of Thermoluminescence

Abstract:  A linear heating system has been developed using field programmable gate array (FPGA) for the measurement of thermoluminescence (TL) in alkali halides and other related compounds. Thermoluminescence plays an essential part in radiation dosimetry. This system measures the temperature and the amount of light emitted by the sample for TL studies. This work proposed an architectural framework, verilog HDL code for protocols for reading temperature from Thermocouple through ADC, processing of data (amount of light energy) in FPGA, sending control signal to the heater and displaying the temperature in LCD. This work shows performance improvement 3 times in comparison with conventional embedded system. The power consumption is also comparatively lower.

Keywords: Thermocouple, field programmable gate array, linear system, thermoluminescence, temperature measurement

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