MEASUREMENT SCIENCE REVIEW            Volume 19      

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No. 1

No. 2 No. 3 No. 4 No. 5 No. 6  

  Measurement of Physical Quantities



Piotr Kuryło, Elena Pivarčiova, Joanna Cyganiuk, Peter Frankovsky: 

Machine Vision System Measuring the Trajectory of Upper Limb Motion Applying the Matlab Software


This paper discusses the problem of possibilities for applying a machine vision in the measurement of the trajectory of the upper limb movement in rehabilitation exercises. The fundamental presumption of designed system was to get the image from the camera’s CCD processor, possibilities of measuring and its processing. As a result of the application system, it is possible to dynamically determine the radius between the shoulder and forearm, and also the angle between the shoulder and the chest of the man, as function of the limb motion. The created system gives the possibility to use a non-invasive method of measurement, allows visualization and full analysis of the rehabilitation progress and also allows keeping electronic records of patients. 



Rudolf Drga, Dagmar Janačova, Rudolf Palenčar, Stanislav Ďuriš:

Positioner and the Procedure for Measuring Spatial Characteristics


The present work focuses on the solution of management of measuring spatial characteristics of security detectors using a positioner, a precision manipulator. It deals with program management software in LabView. Graphical programming with subroutines, which are described as virtual instruments, is used. There are published results of measurements of the spatial characteristics of the PIR detector, where it is preferably used as the measuring station.



Tomaš Kliment, Jaromir Markovič, Dušan Šmigura, Peter Adam1:

Diagnosis of the Accuracy of the Vehicle Scale Using Neural Network


The article describes a method for diagnosing the accuracy of the vehicle scale without using standard weights. The novel method defines the possibility to estimate whether the scale would pass the test for error of indication in the next verification or not, only by using the results from simple tests with load of estimated weight and appropriate classifier. The method is primarily developed for users of these scales. Created classifier is based on the neural network algorithm. The neural network was trained with data from verifications, which are provided by Slovak Legal Metrology. Well trained classifier can provide not only information whether the scale will potentially pass the mentioned test or not, but reliability which is associated with this result as well. In this way, the user has valuable information about the scale in the period between the verifications.



Miroslav Mahdal, Josef Dobeš, Milada Kozubková:

Measurement of Aerodynamic and Acoustic Quantities Describing Flow around a Body Placed in a Wind Tunnel


Aerodynamically generated noise affects passenger comfort in cars, high-speed trains, and airplanes, and thus, automobile manufacturers aim for its reduction. Investigation methods of noise and vibration sources can be divided into two groups, i.e. experimental research and mathematical research. Recently, owing to the increase in computing power, research in aerodynamically generated noise (aero-acoustics) is beginning to use modern methods such as computational fluid dynamics or fluid-structure interaction. The mathematical model of turbulent flow is given by the system of partial differential equations, its solution is ambiguous and thus requires verification by physical experiment. The results of numerical methods are affected by the boundary conditions of high quality gained from the actual experiment. This article describes an application of complex measurement methodology in the aerodynamic and acoustic (vibro-acoustic) fields. The first part of the paper is focused on the specification of the experimental equipment, i.e. the wind tunnel, which was significantly upgraded in order to obtain the relevant aerodynamics and vibro-acoustics data. The paper presents specific results from the measurement of the aerodynamic and vibro-acoustic fields.



Ivana Vranić, Ivona Vranić, Boris Antić, Goran Stojanović, Hani Al-Salami:

Influence of the Main Filter on QRS-amplitude and Duration in Human Electrocardiogram


Accurate measurement of electrocardiograms (ECG) is critical for effective diagnosis of patient’s cardiac functions. Detailed examination of filters’ effects on ECG accuracy, reproducibility and robustness covering a wide range of available commercial products can provide valuable information on the relationship between quality and effectiveness of filters, and assessments of patients’ cardiac functions. In this study, ECG device with 12 leads and built-in filters used for ECG measurements was assessed on human volunteers. Results showed that with respect to measuring QRS wave duration and R-amplitude variation, there was a 4 % inaccuracy when the main filter was ON and OFF, and R-amplitude variation was most pronounced in the V4 lead. Accordingly, variability of R-amplitude and length of QRS wave can be reduced by the use of appropriate lead, and filter activation during the ECG assessment.



Linus Michaeli, Ján Šaliga, Pavol Dolinský, Imrich Andráš: 

Optimization Paradigm in the Signal Recovery after Compressive Sensing


Compressive sensing is a processing approach aiming to reduce the data stream from the observed object with the inherent sparsity using the optimal signal models. The compression of the sparse input signal in time or in the transform domain is performed in the transmitter by the Analog to Information Converter (AIC). The recovery of the compressed signal using optimization based on the differential evolution algorithm is presented in the article as an alternative to the faster pseudoinverse algorithm. Pseudoinverse algorithm results in an unambiguous solution associated with lower compression efficiency. The selection of the mathematically appropriate signal model affects significantly the compression efficiency. On the other hand, the signal model influences the complexity of the algorithm in the receiving block. The suitability of both recovery methods is studied on examples of the signal compression from the passive infrared (PIR) motion sensors or the ECG bioelectric signals.




No. 2  

Measurement of Physical Quantities


Grzegorz Tytko, Leszek Dziczkowski:

Calculation of the Impedance of an E-cored Coil Placed Above a Conductive Material with a Surface Hole


In eddy current testing, probe-coils with the E-type pot core are commonly used for detecting defects in test objects. In this paper, an analytical mathematical model of such a probe placed above a two-layered conductive material with a surface hole has been presented. The final formulas in the closed form that make it possible to calculate the coil impedance were worked out using the truncated region eigenfunction expansion (TREE) method and implemented in Matlab. Changes in resistance and reactance were determined for both material without a hole and for space containing no conductor. The results were compared with those obtained for the air-cored coil and the I-cored coil. The correctness of the calculations was confirmed through experimental measurements and with the finite element method (FEM) in the COMSOL Multiphysics package.



Nan Chen, Shangchun Fan, Dezhi Zheng:

A Phase Difference Measurement Method Based on the Extended Kalman Filter for Coriolis Mass Flowmeters


According to the characteristics of stable single-phase flow, a phase difference measurement method based on the extended Kalman filter is proposed in this paper for use with Coriolis mass flowmeters. Firstly, the Mallat algorithm is applied to filter out interference signals. Then, the frequency and phase difference of the two reconstructed signals are detected through the extended Kalman filter. Compared with the sliding Goertzel algorithm or discrete time Fourier transform, the proposed method does not need to predict the signal frequency and avoids quadratic error. Simulations and experiments show that the proposed method has stronger anti-interference, higher measurement accuracy and lower relative error than the existing method based on the Hilbert transformation.



Milena Kušnerová, Jan Valíček, Marta Harničárová, Jan Kmec, Michal Řepka, Roman Danel, Anton Panda, Zuzana Palková:

The Combined Relative Uncertainty of Measurement Results by Prototype Semi-Automated Calorimetric Chamber


The paper presents an evaluation of the combined relative uncertainty of the result of direct step temperature measurements aimed at evaluation of the indirect measurements of the specific thermal capacity of the heat insulating concrete by means of a pair of resistive cable thermometers fitted with Pt100 temperature sensors and integrated into a computer-controlled calorimetric chamber. In particular, it is a proposal of evaluation of the overall relative uncertainty of the measurement of partial temperatures measured in equidistant time steps, in a relatively wider time interval. In practice, the uncertainty of the result of step temperature measurements is most often declared only by the instrument uncertainty specified by the manufacturer. The exact evaluation of the result of the measurements of thermal and temperature material parameters measured by the calorimetric comparison method is required by the fact that the investigated samples are made of newly designed non-tabulated building materials and that the measurements are made by a prototype device.




Volodymyr Mosorov:

A Cumulative-signals-based Method for Time Delay Estimation


An original method for time delay estimation is presented. It is based on changing input signals into cumulative ones, followed by determination of inflection points of cumulative curves, and estimation of time delay as time difference of these points’ occurrences. To determine the inflection points, a suitable algorithm is proposed. The preliminary results show that the proposed method is sufficiently efficient, especially in the case of flow measurements based on tomography technique when the cross-correlation function of the signals has no evident peak. This method has no limitations on its application for different types of input signals.



Dmytro Kostiuk, Stefan Luby, Peter Siffalovic, Monika Benkovicova, Jan Ivanco, Matej Jergel, Eva Majkova:

Graphene Langmuir-Schaefer films Decorated by Pd Nanoparticles for NO2 and H2 Gas Sensors


NO2 and H2 gas sensing by few-layer graphene (FLG) were studied in dependence on the annealing and decoration of graphene by palladium nanoparticles (NPs). Graphene was deposited onto SiO2 (500 nm)/Si substrates by a modified Langmuir-Schaefer technique. A solution of FLG flakes in 1-methyl-2-pyrrolidone was obtained by a mild sonication of the expanded milled graphite. FLG films were characterized by atomic force microscopy, X-ray diffraction, Raman spectroscopy, and the Brunnauer-Emmett-Teller method. Average FLG flake thickness and lateral dimension were 5 nm and 300 nm, respectively. Drop casting of Pd NP (6–7 nm) solution onto FLG film was applied to decorate graphene by Pd. The room temperature (RT) resistance of the samples was stabilized at 15 kΩ by vacuum annealing. Heating cycles of FLG film revealed its semiconducting character. The gas sensing was tested in the mixtures of dry air with H2 gas (10 to 10 000 ppm) and NO2 gas (2 to 200 ppm) between RT and 200 oC. The response of 26 % to H2 was achieved by FLG with Pd decoration at 70 oC and 10 000 ppm of H2 in the mixture. Pure FLG film did not show any response to H2. The response of FLG with Pd to 6 ppm of NO2  at RT was ≥ 23 %. It is 2 times larger than that of the pure FLG sample. Long term stability of sensors was studied.



Álvaro P. Raposo:

The Algebraic Structure of Quantity Calculus II: Dimensional Analysis and Differential and Integral Calculus


In a previous paper, the author has introduced and studied a new algebraic structure which accurately describes the algebra underlying quantity calculus. The present paper is a continuation of that one, which extends the purely algebraic study by adding two more ingredients: an order structure and a topology. The goal is to give a solid justification of dimensional analysis and differential and integral calculus with quantities.




No. 3  

Measurement of Physical Quantities


Rokas Kvedaras, Vygaudas Kvedaras, Tomas Ustinavičius, Ričardas Masiulionis:

Digital Signal Processing Algorithm for Measurement of Settling Time of High-Resolution High-Speed DACs


The paper presents the developed complex Digital Signal Processing algorithm for the reduction of white and 1/f noise and processing of the measurement signals of the Settling Time Measurement of the Digital-to-Analog Converters. The results show that the proposed DSP algorithm ensures 100-fold suppression of the white noise and 1/f noise. It was shown that it is possible to measure settling times of high-speed DACs (up to 16-17 Bits) with readout levels of ± 0.5 LSB while measurement errors do no exceed ± 1.4 ns.



Tomas Tankeliun, Oleg Zaytsev, Vytautas Urbanavicius:

Hybrid Time-Base Device for Coherent Sampling Oscilloscope


In this paper, a hybrid time-base (HTB) device for the coherent sampling oscilloscope is presented. The HTB device makes it possible to reduce the uncertainty of determining the time position of the sample in the horizontal channel of the sampling oscilloscope. For its functioning, the proposed HTB device requires that the system-under-test, in addition to the test signal, also has a synchronous reference clock – harmonic oscillation. It should be noted that both the test signal and the harmonic reference clock are sampled simultaneously. The harmonic reference clock is connected to one of the oscilloscope channels and a special algorithm processes the clock samples and adjusts the coherent sampling mode. Two techniques of determining the position of the sample on the time axis are combined in the HTB device – the “trigonometric”, when the position is calculated by the arccosine or arcsine formula of the reference clock sampling value, and the interpolation method, according to which the time position of the sample is found by averaging the positions of two adjacent samples, obtained using said “trigonometric” technique. Primary experimental studies have shown that using the HTB device can reduce jitter of the sampling oscilloscope by several times and the drift with constant time distortion components is practically absent in this device.



Mingke Cheng, Feng Gao, Yan Li:

Vibration Detection and Experiment of PMSM High Speed Grinding Motorized Spindle Based on Frequency Domain Technology


The spindle vibrations of the high-speed grinding motorized spindle largely determine the machining quality and precision. In order to accurately predict the spindle vibrations of the PMSM high-speed grinding motorized spindle, the vibration causes are explored and analyzed. The radial vibration, inclined vibration, and axial vibration model are established. The experimental modal analysis method is proposed to analyze the dynamic response of the spindle and to identify the modal parameters of the spindle structure. Thereafter, the frequency response function (FRF) is calculated by self-power spectrum and cross-power spectrum. It is transformed into the vibration spectrum analysis of the spindle. The least-square method is used to fit the radial trajectory of the spindle. This paper aims to propose double standard spheres for 5-DOF spindle vibrations used to detect the spindle vibrations. In the experiment, the method proposed in this paper can effectively and accurately determine the causes of the spindle vibrations. The spectrum analysis and the trajectory are common tools in the spindle vibration detection.



Matej Kucera, Miroslav Gutten, Milan Simko, Milan Sebok, Daniel Korenciak, Roman Jarina, Martin Pitonak:


Electromagnetic Compatibility and Radiation Analysis in Control Room

The article presents a theoretical analysis of electromagnetic compatibility (EMC) and experimental measurement of effects of radiation and acoustic emission of high-voltage transformers for electronic equipment and working personnel in a control room. Electromagnetic compatibility and safety of equipment are not considered as two distinct areas of study in electric and electronic safety. Economic criteria cannot compromise safety but at the same time immunity levels must be relevant in order to establish a “Functional Safety”. Introducing Special Immunity Levels in the level of equipment testing allows us to combine the two areas of EMC and safety. The measurement was carried out in high-current of very high-voltage distribution station. A real-life analysis of effects of electric and electromagnetic field was carried out. FFT was used for mathematical processing of data which were later presented in a graphical form of a spectrally analyzed area. In the last part of the paper we discuss the suitability of acoustic camera to perform contactless monitoring of the health and operation conditions of the power transformer by analyzing acoustic field generated by the transformer core and windings in near control room.



Measurement in Biomedicine


Boris Širaiy, Roman Trobec, Vladimir Ilić:

Quality of One-channel Telemetric ECG Sensor Signal in Maximum Exercise Stress Tests


The aim of this study was to evaluate the quality of the ECG signal, obtained from a telemetric body-sensor device during a maximum stress test on an ergometer. Twenty-three subjects, 13 males, were included in the study (20.56±1.19 years). Two different sensor positions were verified on each subject by the concurrent use of two ECG sensors. Each subject participated in four exercise stress tests: two on a treadmill and two on a cycle ergometer. In the first test, both sensors were attached to self-adhesive skin electrodes on the body, while in the second test the sensors were additionally fixed with self-adhesive tapes. The measurements were compared on both ergometers, in terms of the ECG sensors’ positions and the methods used for the sensors’ fixation. The results showed a significant difference in the running speed that provides an assessable ECG signal between the non-fixed and the fixed sensors at position left inferior (p = 0.000), as well as between the positions left inferior and left superior in the first (p = 0.019), and in the second test (p = 0.000) on the treadmill. On the cycle ergometer the differences were significant between the positions left inferior and left superior in the first (p = 0.000), and the second test (p = 0.003), and between the tests with fixed and non-fixed sensors in the position left superior (p = 0.011). The study confirms that ECG sensors could be used for maximal exercise stress tests in laboratories, especially on a cycle ergometer, and that they present a great potential for future use of ECG sensors during physical activity.



Mohamed F. Issa, Gergely Tuboly, György Kozmann, Zoltan Juhasz:

Automatic ECG Artefact Removal from EEG Signals


Electroencephalography (EEG) signals are frequently contaminated by ocular, muscle, and cardiac artefacts whose removal normally requires manual inspection or the use of reference channels (EOG, EMG, ECG). We present a novel, fully automatic method for the detection and removal of ECG artefacts that works without a reference ECG channel. Independent Component Analysis (ICA) is applied to the measured data and the independent components are examined for the presence of QRS waveforms using an adaptive threshold-based QRS detection algorithm. Detected peaks are subsequently classified by a rule-based classifier as ECG or non-ECG components. Components manifesting ECG activity are marked for removal, and then the artefact-free signal is reconstructed by removing these components before performing the inverse ICA. The performance of the proposed method is evaluated on a number of EEG datasets and compared to results reported in the literature. The average sensitivity of our ECG artefact removal method is above 99 %, which is better than known literature results.




No. 4  

Measurement of Physical Quantities


Mykhaylo Dorozhovets:

Effectiveness of Automatic Correction of Systematic Effects in Measuring Chains


The uncertainty of measurements associated with the following correction methods: advanced correction of additive linear drift, correction of additive and multiplicative effects, as well as joint correction of a linear drift and systematic additive and multiplicative effects is analyzed in the present article. For each correction method sensitivity coefficients and amplitude responses according to which noise and internal and external interferences influence the corrected measurement result have been determined. Besides uncertainty of reference quantities, the main factors which limit the efficiency of correction are: non-linearity of measurement function including non-linearity of ADC, no idealities of the switching systems and external and internal noises and periodic interferences. The efficiency of correction of systematic additive and multiplicative effects was studied for the multifunction 16 bit PCI DAQ of family NI 6250.



Pavel Fiala, Karel Bartušek, Jarmila Dědková, Radim Kadlec, Přemysl Dohnal:

Experimental Measurement of Nanolayers via Electromagnetic, Near Infrared, and Gamma Radiation


We discuss and compare the results obtained from experimental measurements of a two-layer, Ni and TiO2 nanometric structure deposited on siliceous glass. Utilizing previous theoretical models of multilayers or periodic systems and their verifications, the paper focuses on measurement in the NIR, visible, UV, X-ray, and gamma bands of the electromagnetic spectrum; the wavelength of the incident electromagnetic wave is respected. The proposed evaluation comprises a brief description of a Snell’s law-based semi-analytic model of electromagnetic wave propagation through a layered material. We also demonstrate the expected anti-reflective and shielding effects in the X-ray and gamma-ray bands, respectively.



Elena Pivarčiová, Pavol Božek, Kséniia Domnina, Emil Škultéty, Sergey Fedosov:

Interferometric Measurement of Heat Transfer above New Generation Foam Concrete


The contribution is focused on investigating the heat transfer via natural convection which originated as an effect of changed air density by heating the horizontal sample in the area given. For this research we used samples of a new material made in the Russian Federation – the foam concrete which was reinforced by PET fibres. The samples were heated by an electric heating device from the bottom. The temperature fields originating above the horizontal sample surface were visualised by means of the holographic interferometric contactless method in real time. The holographic interferograms of the temperature field were analysed, and then the local heat transfer parameters were calculated: the heat transfer coefficient α, and the heat conductivity coefficient λ.



Jinfei Wang, Orest Kochan, Krzysztof Przystupa, Jun Su:

Information-measuring System to Study the Thermocouple with Controlled Temperature Field


Error due to inhomogeneity is the main problem of thermocouples (TCs), e.g., during the operation of a type K TC, this error can reach 11-30 °C. Thus, metrological reliability of TCs is threatened by this error because there is a high risk of exceeding the permissible error when the temperature distribution along the TC legs changes. Such a large error, in turn, can threaten a proper operation or even safety of a measured object. A TC with controlled temperature field was proposed to cope with this error. An information-measuring system to perform proper measurements, measurement data acquisition and collection to construct mathematical models is proposed. Its property is high diurnal stability of ±(0.0025+0,002(X/XMAX–1) %. The requirements for the information-measuring system and its structure are considered in this paper. In particular, one of the key problems of such a sensor is how stable is its own temperature field under the influence of the temperature field of a measured object. The experimental studies were carried out using the developed system. They showed that the coefficient of penetration of the temperature field of the measured object is about 0.04. This allows decreasing error due to inhomogeneity by about 10-20 times.



Minsheng Guan, Siying Lin, Hongbiao Du, Jie Cui, TaizhouYan:

Evaluation of Damage Indices for Rectangular Concrete-filled Steel Tube Structures


The paper aims to select a simple and effective damage index for estimating the extent of damage of rectangular concrete-filled steel tube (RCFT) structures subjected to ground motions. Two experimental databases of cyclic tests conducted on RCFT columns and frames are compiled. Test results from the database are then used to evaluate six different damage indices, including the ductility ratio (μ), drift ratio, initial-to-secant stiffness ratio (DKJ), modified initial-to-secant stiffness ratio (Dms), energy coefficient (E), and the combined damage index (DPA) as a benchmark indicator. Selection criteria including correlation, efficiency, and proficiency are utilized in the selection process. The optimal alternative for DPA is identified on the basis of a comprehensive evaluation. The evaluations indicate that Dms previously proposed by some of the authors is the most appropriate substitution of DPA, followed by the drift ratio. For the case of the slenderness ratio less than or equal to 30, the same grades of relation between the investigated damage indices and the benchmark are observed. However, in the case of the slenderness ratio larger than 30, the drift ratio tends to be the optimal alternative. In most cases, μ is proved to be an inadequate replacement of DPA.


Meng-Kun Liu, Peng-Yi Weng:

Fault Diagnosis of Ball Bearing Elements: A Generic Procedure based on Time-Frequency Analysis


Motor-driven machines, such as water pumps, air compressors, and fans, are prone to fatigue failures after long operating hours, resulting in catastrophic breakdown. The failures are preceded by faults under which the machines continue to function, but with low efficiency. Most failures that occur frequently in the motor-driven machines are caused by rolling bearing faults, which could be detected by the noise and vibrations during operation. The incipient faults, however, are difficult to identify because of their low signal-to-noise ratio, vulnerability to external disturbances, and non-stationarity. The conventional Fourier spectrum is insufficient for analyzing the transient and non-stationary signals generated by these faults, and hence a novel approach based on wavelet packet decomposition and support vector machine is proposed to distinguish between various types of bearing faults. By using wavelet and statistical methods to extract the features of bearing faults based on time-frequency analysis, the proposed fault diagnosis procedure could identify ball bearing faults successfully.




No. 5  

Measurement of Physical Quantities


Hongru Li, Zaike Tian, He Yu, Baohua Xu:

Fault Prognosis of Hydraulic Pump Based on Bispectrum Entropy and Deep Belief Network


Fault prognosis plays a key role in the framework of Condition-Based Maintenance (CBM). Limited by the inherent disadvantages, most traditional intelligent algorithms perform not very well in fault prognosis of hydraulic pumps. In order to improve the prediction accuracy, a novel methodology for fault prognosis of hydraulic pump based on the bispectrum entropy and the deep belief network is proposed in this paper. Firstly, the bispectrum features of vibration signals are analyzed, and a bispectrum entropy method based on energy distribution is proposed to extract the effective feature for prognostics. Then, the Deep Belief Network (DBN) model based on the Restrict Boltzmann Machine (RBM) is proposed as the prognostics model. For the purpose of accurately predicting the trends and the random fluctuations during the performance degradation of the hydraulic pump, the Quantum Particle Swarm Optimization (QPSO) is introduced to search for the optimal value of initial parameters of the network. Finally, analysis of the hydraulic pump degradation experiment demonstrates that the proposed algorithm has a satisfactory prognostics performance and is feasible to meet the requirements of CBM.



Katy Klauenberg, Gerd Wübbeler, Clemens Elster:

About not Correcting for Systematic Effects


In practice, measurement results are sometimes described by an estimate, which is not the best one as defined in the GUM. Such alternative estimates arise when the result of a measurement is not corrected for all systematic effects. No recommendation exists in the GUM for associating an uncertainty with an uncorrected estimate.
A common choice in guidelines and in the literature is the uncertainty u(y') = root u(2)(y)+(y-y')(2) for an alternative estimate y'. It arises from the expected quadratic loss, on which, also in the GUM, the standard uncertainty u(y), and the best estimate y are based. However, such an uncertainty is not a standard uncertainty and we establish, it may not be used for uncertainty propagation.
One consequence is, for example, that pairs (y', u(y')) are not to be used in calibration certificates.



Peter Pavlasek, Jan Rybař, Stanislav Ďuriš, Jakub Palenčar:

Effects of Quartz Glass Insulation on Platinum Gold Thermocouples


Au/Pt thermocouples are considered as an alternative to High Temperature Platinum Resistance Thermometers and are one of the prime candidates to replace them as the interpolating instrument of the International Temperature Scale of 1990 (ITS-90) in the temperature range between about 660 °C and 962 °C. This work presents the results of investigation of two Au/Pt thermocouples that used exclusively quartz glass (SiO2) as insulation material. Measurement in fixed points of Zn, Al and Ag were realized on these thermocouples as well with interchanged inner insulation made of high purity alumina oxide (Al2O3). The conducted experiments were undertaken to test the performance of Au/Pt thermocouples with use of different insulation materials. The measured electromotive forces were found to be sensitive to the replacement of the quartz glass by alumina oxide as an insulation material of the Au/Pt thermocouples. This change of insulation has resulted in a temperature increase up to about 0.5 K measured at the freezing point of silver. The decreasing insulation resistance of quartz glass at higher temperatures is believed to be the source of thermoelectric instability.



Peng Hu, Zhongyuan Zhou, Jinpeng Li, Xiang Zhou, Mingjie Sheng, Peng Li, Qi Zhou:

Measurement Techniques for Electromagnetic Shielding Behavior of Braided-Shield Power Cables: An Overview and Comparative Study


More and more EMC tests have shown that the radiated emission problems of the equipment under test mainly concentrate on the interconnected power cables and cable connectors. Measurement of shielding performance is a prerequisite for quantitative and qualitative evaluation of the frequency-dependent characteristic of braided-shield power cables and cable connectors. Due to the asymmetric geometric structures of these cable assemblies, compared with the coaxial and symmetrical communication cables, the commonly used transfer impedance testing methods may not be suitable. In view of this, several improved simple and effective measurement methods, including transfer impedance and shield reduction factor testing methods, were proposed in recent years. These methods, based on the equivalent circuit model of the characteristic parameters, provide good repeatability for the measurement of shielding performance. This paper presents an overview analysis of various measurement techniques for shielding performance of power cables and cable connectors, highlights some of its equivalence principle in measurement setups, and showcases a brief comparison between transfer impedance and shield reduction factor.



Ondřej Klempíř, Radim Krupička, Eduard Bakštein, Robert Jech:

Identification of Microrecording Artifacts with Wavelet Analysis and Convolutional Neural Network: An Image Recognition Approach


Deep brain stimulation (DBS) is an internationally accepted form of treatment option for selected patients with Parkinson’s disease and dystonia. Intraoperative extracellular microelectrode recordings (MER) are considered as the standard electrophysiological method for the precise positioning of the DBS electrode into the target brain structure. Pre-processing of MERs is a key phase in clinical analysis, with intraoperative microelectrode recordings being prone to several artifact groups (up to 25%). The aim of this methodological article is to provide a convolutional neural network (CNN) processing pipeline for detection of artifacts in an MER. We applied continuous wavelet transform (CWT) to generate an over-complete time–frequency representation. We demonstrated that when attempting to find artifacts in an MER, the new CNN + CWT provides a high level of accuracy (ACC = 88.1%), identifies individual classes of artifacts (ACC = 75.3%) and also offers artifact time onset detail, which can lead to a reduction in false positives/negatives. In summary, the presented methodology is capable of identifying and removing various artifacts in a comprehensive database of MER and represents a substantial improvement over existing methodology. We believe that this approach will assist in the proposal of interesting clinical hypotheses and will have neurologically relevant effects.



Szabolcs Béres, Lőrinc Holczer, László Hejjel:

On the Minimal Adequate Sampling Frequency of the Photoplethysmogram for Pulse Rate Monitoring and Heart Rate Variability Analysis in Mobile and Wearable Technology


Recently there is great interest in photoplethysmogram signal processing. However, its minimally necessary sampling frequency for accurate heart rate variability parameters is ambiguous. In the present paper frequency-modulated 1.067 Hz cosine wave modelled the variable PPG in silico. The five-minute-long, 1 ms resolution master-signals were decimated (D) at 2-500 ms, then cubic spline interpolated (I) back to 1 ms resolution. The mean pulse rate, standard deviation, root mean square of successive pulse rate differences (RMSSD), and spectral components were computed by Varian 2.3 and compared to the master-series via relative accuracy error. Also Poincaré-plot morphology was assessed. Mean pulse rate is accurate down to 303 ms (D) and 400 ms (I). In low-variability series standard deviation required at least 5 ms (D) and 100 ms (I). RMSSD needed 10 ms (D), and 303 ms (I) with normal, whereas 2 ms (D) and 100 ms (I) in low-variability series. In the frequency domain 5 ms (D) and 100 ms (I) required. 2 ms (D) and 100 ms (I) preserved Poincaré-plot morphology. The minimal sampling frequency of PPG for accurate HRV analysis is higher than expected from the signal bandwidth and sampling theorem. Interpolation improves accuracy. The ratio of sampling error and expected variability should be considered besides the inherent sensitivity of the given parameter, the interpolation technique, and the pulse rate detection method.




No. 6  

Measurement of Physical Quantities


Adam Glowacz, Witold Glowacz, Jarosław Kozik, Krzysztof Piech, Miroslav Gutten, Wahyu Caesarendra, Hui Liu, Frantisek Brumercik, Muhammad Irfan, Z. Faizal Khan

Detection of Deterioration of Three-phase Induction Motor using Vibration Signals


Nowadays detection of deterioration of electrical motors is an important topic of research. Vibration signals often carry diagnostic information of a motor. The authors proposed a setup for the analysis of vibration signals of three-phase induction motors. In this paper rotor fault diagnostic techniques of a three-phase induction motor (TPIM) were presented. The presented techniques used vibration signals and signal processing methods. The authors analyzed the recognition rate of vibration signal readings for 3 states of the TPIM: healthy TPIM, TPIM with 1 broken bar, and TPIM with 2 broken bars. In this paper the authors described a method of the feature extraction of vibration signals Method of Selection of Amplitudes of Frequencies – MSAF-12. Feature vectors were obtained using FFT, MSAF-12, and mean of vector sum. Three methods of classification were used: Nearest Neighbor (NN), Linear Discriminant Analysis (LDA), and Linear Support Vector Machine (LSVM). The obtained results of analyzed classifiers were in the range of 97.61 % – 100 %.



Oleg Chernoyarov, Mariana Marčokova, Alexandra Salnikova, Maksim Maksimov, Alexander Makarov

Measuring the Moment and the Magnitude of the Abrupt Change of the Gaussian Process Bandwidth


The maximum likelihood algorithm is introduced for measuring the unknown moment of abrupt change and bandwidth jump of a fast-fluctuating Gaussian random process. This algorithm can be technically implemented much simpler than the ones obtained by means of common approaches. The technique for calculating the characteristics of the synthesized measurer is presented and the closed analytical expressions for the conditional biases and variances of the resulting estimates are found using the additive local Markov approximation of the decision statistics. By statistical simulation methods, it is confirmed that the presented measurer is operable, while the theoretical formulas describing its performance well approximate the corresponding experimental data in a wide range of the parameter values of the analyzed random process.



Cheng-Yang Liu, Li-Jen Chang

Characterization of Surface Micro-Roughness by Off-Specular Measurements of Polarized Optical Scattering


The characterization of surface micro-roughness is investigated by using off-specular measurements of polarized optical scattering. In the measurement system, the detection angles of optical scattering are defined by the vertical and level scattering angles. The rotating mechanism of angles is controlled by stepper motors. Waveplate and polarizer are used to adjust light polarization and detection. We conduct the optical scattering measurements by using four standard metal sheets of surface roughness. The nominal values (Ra) of standard micro-roughness are 1.6 μm, 0.8 μm, 0.4 μm, and 0.1 μm, respectively. Samples with different surface roughness are evaluated with the utilization of laser sources at three incident wavelengths. These polarized images are analyzed using a computer program to obtain the distribution of light intensity. The results show great correlation between the metal surface roughness and polarization states. This measurement system can be used to quickly and accurately distinguish between different surfaces and properties.



Martina Chvosteková

Multiple Use Confidence Intervals for a Univariate Statistical Calibration


The statistical calibration problem treated here consists of constructing the interval estimates for future unobserved values of a univariate explanatory variable corresponding to an unlimited number of future observations of a univariate response variable. An interval estimate is to be computed for a value x of an explanatory variable after observing a response Yx by using the same calibration data from a single calibration experiment, and it is called the multiple use confidence interval. It is assumed that the normally distributed response variable Yx is related to the explanatory variable x through a linear regression model, a polynomial regression is probably the most frequently used model in industrial applications. Construction of multiple use confidence intervals (MUCI’s) by inverting the tolerance band for a linear regression has been considered by many authors, but the resultant MUCI’s are conservative. A new method for determining MUCI’s is suggested straightforward from their marginal property assuming a distribution of the explanatory variable. Using simulations, we show that the suggested MUCI’s satisfy the coverage probability requirements of MUCI’s quite well and they are narrower than previously published. The practical implementation of the proposed MUCI’s is illustrated in detail on an example.



Tomáš Stejskal, Miroslav Dovica, Tatiana Kelemenová, Dominika Palaščáková, Eduard Jakubkovič, Michal Považan, Štefan Ondočko 

Measurement of Maximum Deviation from Roundness Based on the Inverse Kinematics Principle


The article deals with a special method of measuring the maximum deviation of objects from roundness based on the inverse kinematics principle. The inverse measurement mechanism is based on the immobility of the measuring probes and the object performing all the motions required to measure a dimension. The advantage of this principle is minimization of the temperature change, while the adverse effect in the measurement system is greatly reduced at the same time. The measurement methodology requires a special software evaluation of the data measured. The aim of the given measurement methodology was to establish the maximum roundness deviation that corresponds to the Least Squares Circle (LSC) method. An experiment with three measuring probes was conducted to verify the methodology.



Marian Kampik, Michał Grzenik, Krzysztof Musioł, Krzysztof Kubiczek, Artur Skórkowski, Jerzy Szutkowski, Paweł Zawadzki

Interlaboratory Comparison of Thermal AC Voltage Standards


The article presents results of comparison of the thermal converter of nominal input voltages equal to 10 V from the set of Polish National AC voltage standards, maintained at the Central Office of Measures in Warsaw, with the primary AC voltage 5 V standard, developed and maintained at the AC-DC Transfer Laboratory of the Department of Measurement Science, Electronics and Control at the Faculty of Electrical Engineering of the Silesian University of Technology in Gliwice.





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