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Journal Details
Format
Journal
eISSN
1335-8871
First Published
07 Mar 2008
Publication timeframe
6 times per year
Languages
English

Search

Volume 20 (2020): Issue 2 (April 2020)

Journal Details
Format
Journal
eISSN
1335-8871
First Published
07 Mar 2008
Publication timeframe
6 times per year
Languages
English

Search

6 Articles
Open Access

Importance of Basset History Force for the Description of Magnetically Driven Motion of Magnetic Particles in Air

Published Online: 02 Jun 2020
Page range: 50 - 58

Abstract

Abstract

Lungs are used as an attractive possibility for administration of different therapeutic substances for a long time. An innovative method of such administration widely studied nowadays is the application of aerosolized magnetic particles as the carriers to the lungs in the external non-homogeneous magnetic field. For these reasons we have studied dynamics of such a system on a level of particle trajectory in air in the presence of magnetic force as a driving force exerted on micrometric magnetic particle. On two typical examples of magnetically driven systems—motion of magnetic particle in a gradient magnetic field and cyclotron-like motion of a charged particle in homogeneous magnetic field in microscale, where the external accelerating forces are very large and the relevant time scale is of the order from fraction of milliseconds to seconds, we have examined the importance of these forces. As has been shown, for particles with high initial acceleration, not only the commonly used Stokes force but also the Basset history force should be used for correct description of the motion.

Keywords

  • Aerosol
  • magnetically driven particle motion
  • Stokes force
  • Basset history force
  • Maxey-Riley equation
  • numerical simulation
Open Access

Reliability of Sports Medical Solutions Handgrip and Jamar Handgrip Dynamometer

Published Online: 02 Jun 2020
Page range: 59 - 64

Abstract

Abstract

The aim of this paper is to determine inter-reliability, concurrent validity, and interchangeability of the SMS HG dynamometric system and a Jamar digital dynamometer for hand grip strength measurements performed in two relevant positions of the elbow joint, i.e. 90 ° flexion and 180 ° (full) extension. The sample in this research consisted of 61 participants and included 27 women and 34 men. Statistically significant differences in the results found between two positions in the elbow joint indicate that the results must be evaluated separately. However, regarding both testing positions, i.e. 90 ° flexion and 180 ° extension in the elbow joint, it was determined that SMS HG and Jamar instruments have a very high level of inter-reliability (ICC 0.948 to 0.980), but lack concurrent validity. The established mean difference of the results was higher for the 90 ° than for the 180 ° position but in both cases was considered to have a practical significance, thus not supporting the interchangeability of the instruments.

Keywords

  • handgrip strength
  • dynamometry
  • strain gage
  • digital dynamometer
  • elbow angle
Open Access

Computer Modelling of Two-level Digital Frequency Synthesizer with Poisson Probability Distribution of Output Pulses

Published Online: 02 Jun 2020
Page range: 65 - 72

Abstract

Abstract

The article presents the modified structure of the two-level digital frequency synthesizer (TLDFS), which combines the properties of classical digital frequency synthesizers (DFS) and Poisson pulse sequence generators (PPSG). The analysis of the statistical characteristics of synthesizer output signal, obtained in computer modelling with the use of appropriate software, has been carried out, which allowed determining the effective range of values of its control codes. The proposed generators can be effectively used to simulate various natural and technical processes, in particular, to simulate the output signals of dosimetric detectors during the design, adjustment and testing of dosimetric devices.

Keywords

  • Digital frequency synthesizer
  • Poisson pulse sequence
  • statistical characteristics
  • computer modelling
Open Access

Matrix Presentation of Uncertainties Propagation in the Realization of ITS-90 Temperature Scale using Standard Platinum Resistance Thermometers

Published Online: 02 Jun 2020
Page range: 73 - 79

Abstract

Abstract

The paper presents a matrix approach to the propagation of uncertainties in the realization of the ITS-90 using Standard Platinum Resistance Thermometers (SPRT) calibrated at Defining Fixed Points (DFPs). The procedure allows correlations to be included between SPRT resistances measured during the calibration at the DFPs (i.e., the realization of the ITS-90) and the resistances measured during the subsequent use of the SPRT to measure temperature T90. The example also shows the possible contribution of these correlations to the overall temperature uncertainty measured by a calibrated SPRT.

Keywords

  • Uncertainty
  • correlation
  • standard platinum resistance thermometer (SPRT)
  • ITS-90
  • matrix algebra
Open Access

Gaussian Recursive Filter for Nonlinear Systems with Finite-step Correlated Noises and Packet Dropout Compensations

Published Online: 02 Jun 2020
Page range: 80 - 92

Abstract

Abstract

This paper is focused on the nonlinear state estimation problem with finite-step correlated noises and packet loss. Firstly, by using the projection theorem repeatedly, the mean and covariance of process noise and measurement noise in the condition of measurements before the current epoch are calculated. Then, based on the Gaussian approximation recursive filter (GASF) and the prediction compensation mechanism, one-step predictor and filter with packet dropouts are derived, respectively. Based on these, a nonlinear Gaussian recursive filter is proposed. Subsequently, the numerical implementation is derived based on the cubature Kalman filter (CKF), which is suitable for general nonlinear system and with higher accuracy compared to the algorithm expanded from linear system to nonlinear system through Taylor series expansion. Finally, the strong nonlinearity model is used to show the superiority of the proposed algorithm.

Keywords

  • Gaussian recursive filter
  • dropout compensations
  • Gaussian approximation
  • numerical implementation
Open Access

Oil Phase Velocity Measurement of Oil-Water Two-Phase Flow with Low Velocity and High Water Cut Using the Improved ORB and RANSAC Algorithm

Published Online: 02 Jun 2020
Page range: 93 - 103

Abstract

Abstract

Velocity is an important parameter for fluid flow characteristics in profile logging. Particle tracking velocimetry (PTV) technology is often used to study the flow characteristics of oil wells with low flow velocity and high water cut, and the key to PTV technology is particle matching. The existing particle matching algorithms of PTV technology do not meet the matching demands of oil drops in the oil phase velocity measurement of oil-water two-phase flow with low velocity and high water cut. To raise the particle matching precision, we improved the particle matching algorithm from the oriented FAST and the rotated BRIEF (ORB) feature description and the random sample consensus (RANSAC) algorithm. The simulation and experiment were carried out. Simulation results show that the improved algorithm not only increases the number of matching points but also reduces the computation. The experiment shows that the improved algorithm in this paper not only reduces the computation of the feature description process, reaching half of the computation amount of the original algorithm, but also increases the number of matching results, thus improving the measurement accuracy of oil phase velocity. Compared with the SIFT algorithm and the ORB algorithm, the improved algorithm has the largest number of matching point pairs. And the variation coefficient of this algorithm is 0.039, which indicates that the algorithm is stable. The mean error of oil phase velocity measurement of the improved algorithm is 1.20 %, and the maximum error is 6.16 %, which is much lower than the maximum error of PTV, which is 25.89 %. The improved algorithm overcomes the high computation cost of the SIFT algorithm and achieves the precision of the SIFT algorithm. Therefore, this study contributes to the improvement of the measurement accuracy of oil phase velocity and provides reliable production logging data for oilfield.

Keywords

  • ORB
  • RANSAC
  • oil-water two-phase flow
  • PTV
6 Articles
Open Access

Importance of Basset History Force for the Description of Magnetically Driven Motion of Magnetic Particles in Air

Published Online: 02 Jun 2020
Page range: 50 - 58

Abstract

Abstract

Lungs are used as an attractive possibility for administration of different therapeutic substances for a long time. An innovative method of such administration widely studied nowadays is the application of aerosolized magnetic particles as the carriers to the lungs in the external non-homogeneous magnetic field. For these reasons we have studied dynamics of such a system on a level of particle trajectory in air in the presence of magnetic force as a driving force exerted on micrometric magnetic particle. On two typical examples of magnetically driven systems—motion of magnetic particle in a gradient magnetic field and cyclotron-like motion of a charged particle in homogeneous magnetic field in microscale, where the external accelerating forces are very large and the relevant time scale is of the order from fraction of milliseconds to seconds, we have examined the importance of these forces. As has been shown, for particles with high initial acceleration, not only the commonly used Stokes force but also the Basset history force should be used for correct description of the motion.

Keywords

  • Aerosol
  • magnetically driven particle motion
  • Stokes force
  • Basset history force
  • Maxey-Riley equation
  • numerical simulation
Open Access

Reliability of Sports Medical Solutions Handgrip and Jamar Handgrip Dynamometer

Published Online: 02 Jun 2020
Page range: 59 - 64

Abstract

Abstract

The aim of this paper is to determine inter-reliability, concurrent validity, and interchangeability of the SMS HG dynamometric system and a Jamar digital dynamometer for hand grip strength measurements performed in two relevant positions of the elbow joint, i.e. 90 ° flexion and 180 ° (full) extension. The sample in this research consisted of 61 participants and included 27 women and 34 men. Statistically significant differences in the results found between two positions in the elbow joint indicate that the results must be evaluated separately. However, regarding both testing positions, i.e. 90 ° flexion and 180 ° extension in the elbow joint, it was determined that SMS HG and Jamar instruments have a very high level of inter-reliability (ICC 0.948 to 0.980), but lack concurrent validity. The established mean difference of the results was higher for the 90 ° than for the 180 ° position but in both cases was considered to have a practical significance, thus not supporting the interchangeability of the instruments.

Keywords

  • handgrip strength
  • dynamometry
  • strain gage
  • digital dynamometer
  • elbow angle
Open Access

Computer Modelling of Two-level Digital Frequency Synthesizer with Poisson Probability Distribution of Output Pulses

Published Online: 02 Jun 2020
Page range: 65 - 72

Abstract

Abstract

The article presents the modified structure of the two-level digital frequency synthesizer (TLDFS), which combines the properties of classical digital frequency synthesizers (DFS) and Poisson pulse sequence generators (PPSG). The analysis of the statistical characteristics of synthesizer output signal, obtained in computer modelling with the use of appropriate software, has been carried out, which allowed determining the effective range of values of its control codes. The proposed generators can be effectively used to simulate various natural and technical processes, in particular, to simulate the output signals of dosimetric detectors during the design, adjustment and testing of dosimetric devices.

Keywords

  • Digital frequency synthesizer
  • Poisson pulse sequence
  • statistical characteristics
  • computer modelling
Open Access

Matrix Presentation of Uncertainties Propagation in the Realization of ITS-90 Temperature Scale using Standard Platinum Resistance Thermometers

Published Online: 02 Jun 2020
Page range: 73 - 79

Abstract

Abstract

The paper presents a matrix approach to the propagation of uncertainties in the realization of the ITS-90 using Standard Platinum Resistance Thermometers (SPRT) calibrated at Defining Fixed Points (DFPs). The procedure allows correlations to be included between SPRT resistances measured during the calibration at the DFPs (i.e., the realization of the ITS-90) and the resistances measured during the subsequent use of the SPRT to measure temperature T90. The example also shows the possible contribution of these correlations to the overall temperature uncertainty measured by a calibrated SPRT.

Keywords

  • Uncertainty
  • correlation
  • standard platinum resistance thermometer (SPRT)
  • ITS-90
  • matrix algebra
Open Access

Gaussian Recursive Filter for Nonlinear Systems with Finite-step Correlated Noises and Packet Dropout Compensations

Published Online: 02 Jun 2020
Page range: 80 - 92

Abstract

Abstract

This paper is focused on the nonlinear state estimation problem with finite-step correlated noises and packet loss. Firstly, by using the projection theorem repeatedly, the mean and covariance of process noise and measurement noise in the condition of measurements before the current epoch are calculated. Then, based on the Gaussian approximation recursive filter (GASF) and the prediction compensation mechanism, one-step predictor and filter with packet dropouts are derived, respectively. Based on these, a nonlinear Gaussian recursive filter is proposed. Subsequently, the numerical implementation is derived based on the cubature Kalman filter (CKF), which is suitable for general nonlinear system and with higher accuracy compared to the algorithm expanded from linear system to nonlinear system through Taylor series expansion. Finally, the strong nonlinearity model is used to show the superiority of the proposed algorithm.

Keywords

  • Gaussian recursive filter
  • dropout compensations
  • Gaussian approximation
  • numerical implementation
Open Access

Oil Phase Velocity Measurement of Oil-Water Two-Phase Flow with Low Velocity and High Water Cut Using the Improved ORB and RANSAC Algorithm

Published Online: 02 Jun 2020
Page range: 93 - 103

Abstract

Abstract

Velocity is an important parameter for fluid flow characteristics in profile logging. Particle tracking velocimetry (PTV) technology is often used to study the flow characteristics of oil wells with low flow velocity and high water cut, and the key to PTV technology is particle matching. The existing particle matching algorithms of PTV technology do not meet the matching demands of oil drops in the oil phase velocity measurement of oil-water two-phase flow with low velocity and high water cut. To raise the particle matching precision, we improved the particle matching algorithm from the oriented FAST and the rotated BRIEF (ORB) feature description and the random sample consensus (RANSAC) algorithm. The simulation and experiment were carried out. Simulation results show that the improved algorithm not only increases the number of matching points but also reduces the computation. The experiment shows that the improved algorithm in this paper not only reduces the computation of the feature description process, reaching half of the computation amount of the original algorithm, but also increases the number of matching results, thus improving the measurement accuracy of oil phase velocity. Compared with the SIFT algorithm and the ORB algorithm, the improved algorithm has the largest number of matching point pairs. And the variation coefficient of this algorithm is 0.039, which indicates that the algorithm is stable. The mean error of oil phase velocity measurement of the improved algorithm is 1.20 %, and the maximum error is 6.16 %, which is much lower than the maximum error of PTV, which is 25.89 %. The improved algorithm overcomes the high computation cost of the SIFT algorithm and achieves the precision of the SIFT algorithm. Therefore, this study contributes to the improvement of the measurement accuracy of oil phase velocity and provides reliable production logging data for oilfield.

Keywords

  • ORB
  • RANSAC
  • oil-water two-phase flow
  • PTV

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