Issues

Journal & Issues

Volume 22 (2022): Issue 5 (October 2022)

Volume 22 (2022): Issue 4 (August 2022)

Volume 22 (2022): Issue 3 (June 2022)

Volume 22 (2022): Issue 2 (April 2022)

Volume 22 (2022): Issue 1 (February 2022)

Volume 21 (2021): Issue 6 (December 2021)

Volume 21 (2021): Issue 5 (October 2021)

Volume 21 (2021): Issue 4 (August 2021)

Volume 21 (2021): Issue 3 (June 2021)

Volume 21 (2021): Issue 2 (April 2021)

Volume 21 (2021): Issue 1 (February 2021)

Volume 20 (2020): Issue 5 (October 2020)

Volume 20 (2020): Issue 4 (August 2020)

Volume 20 (2020): Issue 3 (June 2020)

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

Volume 20 (2020): Issue 1 (February 2020)

Volume 19 (2019): Issue 6 (December 2019)

Volume 19 (2019): Issue 5 (October 2019)

Volume 19 (2019): Issue 4 (August 2019)

Volume 19 (2019): Issue 3 (June 2019)

Volume 19 (2019): Issue 2 (April 2019)

Volume 19 (2019): Issue 1 (February 2019)

Volume 18 (2018): Issue 6 (October 2018)

Volume 18 (2018): Issue 5 (October 2018)

Volume 18 (2018): Issue 4 (August 2018)

Volume 18 (2018): Issue 3 (June 2018)

Volume 18 (2018): Issue 2 (April 2018)

Volume 18 (2018): Issue 1 (February 2018)

Volume 17 (2017): Issue 6 (December 2017)

Volume 17 (2017): Issue 5 (October 2017)

Volume 17 (2017): Issue 3 (June 2017)

Volume 17 (2017): Issue 2 (April 2017)

Volume 17 (2017): Issue 1 (February 2017)

Volume 16 (2016): Issue 6 (December 2016)

Volume 16 (2016): Issue 5 (October 2016)

Volume 16 (2016): Issue 4 (August 2016)

Volume 16 (2016): Issue 3 (June 2016)

Volume 16 (2016): Issue 2 (April 2016)

Volume 16 (2016): Issue 1 (February 2016)

Volume 15 (2015): Issue 6 (December 2015)

Volume 15 (2015): Issue 5 (October 2015)

Volume 15 (2015): Issue 4 (August 2015)

Volume 15 (2015): Issue 3 (June 2015)

Volume 15 (2015): Issue 2 (April 2015)

Volume 15 (2015): Issue 1 (February 2015)

Volume 14 (2014): Issue 6 (December 2014)

Volume 14 (2014): Issue 5 (October 2014)

Volume 14 (2014): Issue 4 (August 2014)

Volume 14 (2014): Issue 3 (June 2014)

Volume 14 (2014): Issue 2 (April 2014)

Volume 14 (2014): Issue 1 (February 2014)

Volume 13 (2013): Issue 6 (December 2013)

Volume 13 (2013): Issue 5 (October 2013)

Volume 13 (2013): Issue 4 (August 2013)

Volume 13 (2013): Issue 3 (June 2013)

Volume 13 (2013): Issue 2 (April 2013)

Volume 13 (2013): Issue 1 (February 2013)

Volume 12 (2012): Issue 6 (December 2012)

Volume 12 (2012): Issue 5 (October 2012)

Volume 12 (2012): Issue 4 (August 2012)

Volume 12 (2012): Issue 3 (June 2012)

Volume 12 (2012): Issue 2 (April 2012)

Volume 12 (2012): Issue 1 (February 2012)

Volume 11 (2011): Issue 6 (December 2011)

Volume 11 (2011): Issue 5 (October 2011)

Volume 11 (2011): Issue 4 (August 2011)

Volume 11 (2011): Issue 3 (June 2011)

Volume 11 (2011): Issue 2 (April 2011)

Volume 11 (2011): Issue 1 (February 2011)

Volume 10 (2010): Issue 6 (December 2010)

Volume 10 (2010): Issue 5 (October 2010)

Volume 10 (2010): Issue 4 (August 2010)

Volume 10 (2010): Issue 3 (June 2010)

Volume 10 (2010): Issue 2 (April 2010)

Volume 10 (2010): Issue 1 (February 2010)

Volume 9 (2009): Issue 6 (December 2009)

Volume 9 (2009): Issue 5 (October 2009)

Volume 9 (2009): Issue 4 (August 2009)

Volume 9 (2009): Issue 3 (June 2009)

Volume 9 (2009): Issue 2 (April 2009)

Volume 9 (2009): Issue 1 (February 2009)

Volume 8 (2008): Issue 6 (December 2008)

Volume 8 (2008): Issue 5 (October 2008)

Volume 8 (2008): Issue 4 (August 2008)

Volume 8 (2008): Issue 3 (June 2008)

Volume 8 (2008): Issue 2 (April 2008)

Volume 8 (2008): Issue 1 (February 2008)

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

Search

Volume 15 (2015): Issue 2 (April 2015)

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

Search

6 Articles
access type Open Access

On Location Estimation Technique Based of the Time of Flight in Low-power Wireless Systems

Published Online: 09 Jun 2015
Page range: 58 - 63

Abstract

Abstract

This study deals with the distance estimation issue in low-power wireless systems being usually used for sensor networking and interconnecting the Internet of Things. There is an effort to locate or track these sensor entities for different needs the radio signal time of flight principle from the theoretical and practical side of application research is evaluated. Since these sensor devices are mainly targeted for low power consumption appliances, there is always need for optimization of any aspects needed for regular sensor operation. For the distance estimation we benefit from IEEE 802.15.4a technology, which offers the precise ranging capabilities. There is no need for additional hardware to be used for the ranging task and all fundamental measurements are acquired within the 15.4a standard compliant hardware in the real environment. The proposed work examines the problems and the solutions for implementation of distance estimation algorithms for WSN devices. The main contribution of the article is seen in this real testbed evaluation of the ranging technology.

Keywords

  • Distance Estimation
  • IEEE 802.15.4a
  • Localization
  • ToF
  • UWB.
access type Open Access

Analysis and Experimental Evaluation of Power Line Transmission Parameters for Power Line Communication

Published Online: 09 Jun 2015
Page range: 64 - 71

Abstract

Abstract

The article describes a way of evaluating the power line channel frequency response and input impedance by means of the linear time-invariant (LTI) power line generator. Two possible methods are introduced for the calculation of primary parameters: the first method depends on the physical realization and physical dimension of the cable, and the second method is derived from the data provided by typical electrical cable manufacturers. Based on these methods, a comparison of transfer functions was made. This is followed by measurement evaluation and numerical verification on a simple topology

Keywords

  • Power line communication
  • primary parameters
  • time-invariant system
  • transfer function
  • simulation
  • measurement
access type Open Access

Application of the Monte Carlo Method for the Estimation of Uncertainty in Radiofrequency Field Spot Measurements

Published Online: 09 Jun 2015
Page range: 72 - 76

Abstract

Abstract

The objective of the present work is the application of the Monte Carlo method (GUMS1) for evaluating uncertainty in electromagnetic field measurements and the comparison of the results with the ones obtained using the 'standard' method (GUM). In particular, the two methods are applied in order to evaluate the field measurement uncertainty using a frequency selective radiation meter and the Total Exposure Quotient (TEQ) uncertainty. Comparative results are presented in order to highlight cases where GUMS1 results deviate significantly from the ones obtained using GUM, such as the presence of a non-linear mathematical model connecting the inputs with the output quantity (case of the TEQ model) or the presence of a dominant nonnormal distribution of an input quantity (case of U-shaped mismatch uncertainty). The deviation of the results obtained from the two methods can even lead to different decisions regarding the conformance with the exposure reference levels.

Keywords

  • Uncertainty
  • Monte Carlo
  • exposure quotient
  • electromagnetic field measurements
  • human exposure
access type Open Access

Rogowski Coil for Current Measurement in a Cryogenic Environment

Published Online: 09 Jun 2015
Page range: 77 - 84

Abstract

Abstract

A Rogowski coil based sensor for current measurement in a cryogenic environment and results of its application for paralleled high temperature superconducting (HTS) coil current sharing are presented. The current sensor consists of a Rogowski coil and an integrator, where the coil output voltage is proportional to the derivative of primary current and the integrator transfers the differentiation to normal state. The Rogowski coil has promising applicability at cryogenic circumstance because its body is made of low temperature materials. The integrator ensures a large bandwidth with feasible magnitude, which is vital for dynamic current measurement during the quench of the HTS coil. The proposed current sensor is used for current sharing measurement of two paralleled Bi2223 HTS coils, and the experimental results show that the measurement precision is better than 0.5%.

Keywords

  • Rogowski coil
  • integrator
  • current measurement
  • high temperature superconducting coil
  • cryogenic.
access type Open Access

Determination of Radiative Heat Transfer Coefficient at High Temperatures Using a Combined Experimental-Computational Technique

Published Online: 09 Jun 2015
Page range: 85 - 91

Abstract

Abstract

The radiative heat transfer coefficient at high temperatures is determined using a combination of experimental measurement and computational modeling. In the experimental part, cement mortar specimen is heated in a laboratory furnace to 600°C and the temperature field inside is recorded using built-in K-type thermocouples connected to a data logger. The measured temperatures are then used as input parameters in the three dimensional computational modeling whose objective is to find the best correlation between the measured and calculated data via four free parameters, namely the thermal conductivity of the specimen, effective thermal conductivity of thermal insulation, and heat transfer coefficients at normal and high temperatures. The optimization procedure which is performed using the genetic algorithms provides the value of the high-temperature radiative heat transfer coefficient of 3.64 W/(m2K).

Keywords

  • Radiative heat transfer coefficient
  • high temperatures
  • thermocouples
  • genetic algorithms
  • cement mortar
access type Open Access

An FPGA Architecture for Extracting Real-Time Zernike Coefficients from Measured Phase Gradients

Published Online: 09 Jun 2015
Page range: 92 - 100

Abstract

Abstract

Zernike modes are commonly used in adaptive optics systems to represent optical wavefronts. However, real-time calculation of Zernike modes is time consuming due to two factors: the large factorial components in the radial polynomials used to define them and the large inverse matrix calculation needed for the linear fit. This paper presents an efficient parallel method for calculating Zernike coefficients from phase gradients produced by a Shack-Hartman sensor and its real-time implementation using an FPGA by pre-calculation and storage of subsections of the large inverse matrix. The architecture exploits symmetries within the Zernike modes to achieve a significant reduction in memory requirements and a speed-up of 2.9 when compared to published results utilising a 2D-FFT method for a grid size of 8×8. Analysis of processor element internal word length requirements show that 24-bit precision in precalculated values of the Zernike mode partial derivatives ensures less than 0.5% error per Zernike coefficient and an overall error of <1%. The design has been synthesized on a Xilinx Spartan-6 XC6SLX45 FPGA. The resource utilisation on this device is <3% of slice registers, <15% of slice LUTs, and approximately 48% of available DSP blocks independent of the Shack-Hartmann grid size. Block RAM usage is <16% for Shack-Hartmann grid sizes up to 32×32.

Keywords

  • Singular value decomposition
  • field programmable gate array
6 Articles
access type Open Access

On Location Estimation Technique Based of the Time of Flight in Low-power Wireless Systems

Published Online: 09 Jun 2015
Page range: 58 - 63

Abstract

Abstract

This study deals with the distance estimation issue in low-power wireless systems being usually used for sensor networking and interconnecting the Internet of Things. There is an effort to locate or track these sensor entities for different needs the radio signal time of flight principle from the theoretical and practical side of application research is evaluated. Since these sensor devices are mainly targeted for low power consumption appliances, there is always need for optimization of any aspects needed for regular sensor operation. For the distance estimation we benefit from IEEE 802.15.4a technology, which offers the precise ranging capabilities. There is no need for additional hardware to be used for the ranging task and all fundamental measurements are acquired within the 15.4a standard compliant hardware in the real environment. The proposed work examines the problems and the solutions for implementation of distance estimation algorithms for WSN devices. The main contribution of the article is seen in this real testbed evaluation of the ranging technology.

Keywords

  • Distance Estimation
  • IEEE 802.15.4a
  • Localization
  • ToF
  • UWB.
access type Open Access

Analysis and Experimental Evaluation of Power Line Transmission Parameters for Power Line Communication

Published Online: 09 Jun 2015
Page range: 64 - 71

Abstract

Abstract

The article describes a way of evaluating the power line channel frequency response and input impedance by means of the linear time-invariant (LTI) power line generator. Two possible methods are introduced for the calculation of primary parameters: the first method depends on the physical realization and physical dimension of the cable, and the second method is derived from the data provided by typical electrical cable manufacturers. Based on these methods, a comparison of transfer functions was made. This is followed by measurement evaluation and numerical verification on a simple topology

Keywords

  • Power line communication
  • primary parameters
  • time-invariant system
  • transfer function
  • simulation
  • measurement
access type Open Access

Application of the Monte Carlo Method for the Estimation of Uncertainty in Radiofrequency Field Spot Measurements

Published Online: 09 Jun 2015
Page range: 72 - 76

Abstract

Abstract

The objective of the present work is the application of the Monte Carlo method (GUMS1) for evaluating uncertainty in electromagnetic field measurements and the comparison of the results with the ones obtained using the 'standard' method (GUM). In particular, the two methods are applied in order to evaluate the field measurement uncertainty using a frequency selective radiation meter and the Total Exposure Quotient (TEQ) uncertainty. Comparative results are presented in order to highlight cases where GUMS1 results deviate significantly from the ones obtained using GUM, such as the presence of a non-linear mathematical model connecting the inputs with the output quantity (case of the TEQ model) or the presence of a dominant nonnormal distribution of an input quantity (case of U-shaped mismatch uncertainty). The deviation of the results obtained from the two methods can even lead to different decisions regarding the conformance with the exposure reference levels.

Keywords

  • Uncertainty
  • Monte Carlo
  • exposure quotient
  • electromagnetic field measurements
  • human exposure
access type Open Access

Rogowski Coil for Current Measurement in a Cryogenic Environment

Published Online: 09 Jun 2015
Page range: 77 - 84

Abstract

Abstract

A Rogowski coil based sensor for current measurement in a cryogenic environment and results of its application for paralleled high temperature superconducting (HTS) coil current sharing are presented. The current sensor consists of a Rogowski coil and an integrator, where the coil output voltage is proportional to the derivative of primary current and the integrator transfers the differentiation to normal state. The Rogowski coil has promising applicability at cryogenic circumstance because its body is made of low temperature materials. The integrator ensures a large bandwidth with feasible magnitude, which is vital for dynamic current measurement during the quench of the HTS coil. The proposed current sensor is used for current sharing measurement of two paralleled Bi2223 HTS coils, and the experimental results show that the measurement precision is better than 0.5%.

Keywords

  • Rogowski coil
  • integrator
  • current measurement
  • high temperature superconducting coil
  • cryogenic.
access type Open Access

Determination of Radiative Heat Transfer Coefficient at High Temperatures Using a Combined Experimental-Computational Technique

Published Online: 09 Jun 2015
Page range: 85 - 91

Abstract

Abstract

The radiative heat transfer coefficient at high temperatures is determined using a combination of experimental measurement and computational modeling. In the experimental part, cement mortar specimen is heated in a laboratory furnace to 600°C and the temperature field inside is recorded using built-in K-type thermocouples connected to a data logger. The measured temperatures are then used as input parameters in the three dimensional computational modeling whose objective is to find the best correlation between the measured and calculated data via four free parameters, namely the thermal conductivity of the specimen, effective thermal conductivity of thermal insulation, and heat transfer coefficients at normal and high temperatures. The optimization procedure which is performed using the genetic algorithms provides the value of the high-temperature radiative heat transfer coefficient of 3.64 W/(m2K).

Keywords

  • Radiative heat transfer coefficient
  • high temperatures
  • thermocouples
  • genetic algorithms
  • cement mortar
access type Open Access

An FPGA Architecture for Extracting Real-Time Zernike Coefficients from Measured Phase Gradients

Published Online: 09 Jun 2015
Page range: 92 - 100

Abstract

Abstract

Zernike modes are commonly used in adaptive optics systems to represent optical wavefronts. However, real-time calculation of Zernike modes is time consuming due to two factors: the large factorial components in the radial polynomials used to define them and the large inverse matrix calculation needed for the linear fit. This paper presents an efficient parallel method for calculating Zernike coefficients from phase gradients produced by a Shack-Hartman sensor and its real-time implementation using an FPGA by pre-calculation and storage of subsections of the large inverse matrix. The architecture exploits symmetries within the Zernike modes to achieve a significant reduction in memory requirements and a speed-up of 2.9 when compared to published results utilising a 2D-FFT method for a grid size of 8×8. Analysis of processor element internal word length requirements show that 24-bit precision in precalculated values of the Zernike mode partial derivatives ensures less than 0.5% error per Zernike coefficient and an overall error of <1%. The design has been synthesized on a Xilinx Spartan-6 XC6SLX45 FPGA. The resource utilisation on this device is <3% of slice registers, <15% of slice LUTs, and approximately 48% of available DSP blocks independent of the Shack-Hartmann grid size. Block RAM usage is <16% for Shack-Hartmann grid sizes up to 32×32.

Keywords

  • Singular value decomposition
  • field programmable gate array

Plan your remote conference with Sciendo