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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 10 (2010): Issue 6 (December 2010)

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

Model Based Determination of Detection Limits for Proton Transfer Reaction Mass Spectrometer

Published Online: 20 Jan 2011
Page range: 180 - 188

Abstract

Model Based Determination of Detection Limits for Proton Transfer Reaction Mass Spectrometer

Proton Transfer Reaction Mass Spectrometry (PTR-MS) is a chemical ionization mass spectrometric technique which allows to measure trace gases as, for example, in exhaled human breath. The quantification of compounds at low concentrations is desirable for medical diagnostics. Typically, an increase of measuring accuracy can be achieved if the duration of the measuring process is extended. For real time measurements the time windows for measurement are relatively short, in order to get a good time resolution (e.g. with breath-to-breath resolution during exercise on a stationary bicycle). Determination of statistical detection limits is typically based on calibration measurements, but this approach is limited, especially for very low concentrations. To overcome this problem, a calculation of limit of quantification (LOQ) and limit of detection (LOD), respectively, based on a theoretical model of the measurement process is outlined.

Keywords

  • Detection limits
  • limit of quantification
  • limit of detection
  • mass spectrometry
  • PTR-MS
access type Open Access

Estimation and Tracking of the Power Quality Disturbances in the Frequency Domain

Published Online: 20 Jan 2011
Page range: 189 - 194

Abstract

Estimation and Tracking of the Power Quality Disturbances in the Frequency Domain

In this paper, simple algorithms for fast measurement and estimation of the unknown changing frequency, amplitude, and phase difference of the sinusoidal signals from two channels with the same frequency, as well as other parameters for evaluation of the power quality disturbances, are presented. Parameters are calculated from the DFT coefficients around the component peaks. The improvement for reducing the influences of the harmonic components is the estimation with the three-point interpolation and the Hann window.

Keywords

  • Power quality
  • voltage quality
  • disturbance estimation
  • frequency domain
  • non-coherency
access type Open Access

Modelling and Simulation of the Pyroelectric Detector Using MATLAB/Simulink

Published Online: 20 Jan 2011
Page range: 195 - 199

Abstract

Modelling and Simulation of the Pyroelectric Detector Using MATLAB/Simulink

An attempt was made to obtain a simple Laplace transfer function model of a pyroelectric detector which would make an excellent basis for the analysis of its dynamic behaviour. Knowledge of the transfer function model of the pyroelectric detector is necessary for its simulation studies in MATLAB/Simulink environment. A simple model of the pyroelectric detector was implemented in MATLAB/Simulink and some exemplary results of investigation of its voltage response to incident radiation and frequency characteristics were presented.

Keywords

  • modelling of pyroelectric detector
  • transfer function model of pyroelectric detector
  • simulation of pyroelectric detector
access type Open Access

Traceability of Voltage Measurements for Non-Sinusoidal Waveforms

Published Online: 20 Jan 2011
Page range: 200 - 204

Abstract

Traceability of Voltage Measurements for Non-Sinusoidal Waveforms

This paper describes the result of work performed at the Laboratoire National de Métrologie et d'Essais (LNE) aiming at developing a standard system to measure RMS value and harmonic contents of distorted voltage waveforms by means of a sampling voltmeter. Thermal converters are used to trace the RMS value to the SI units. The error of the DVM has been generally found less than 10 μV/V up to 2 kHz but can reach about 50 μV/V at 2.5 kHz for RMS voltage measurements for sine waves. For distorted waveforms, deviations within 15 μV/V have been obtained whatever the total harmonic distortion of the waveforms.

Keywords

  • distorted voltage waveforms
  • thermal converters
  • sampling techniques
  • analog to digital converters
access type Open Access

Frequency Selection of Sine Wave for Dynamic ADC Test

Published Online: 20 Jan 2011
Page range: 205 - 208

Abstract

Frequency Selection of Sine Wave for Dynamic ADC Test

The paper deals with determination of an optimum frequency for the time domain and frequency domain ADC testing. Proposed algorithm for selection of test signal frequency fulfills two common requirements. The first requirement is to get maximum quantity of distinct phases of the sampled values which are uniformly distributed between 0 and 2π; the second one is to avoid overlapping of higher harmonic components aliased in the first Nyquist zone. The algorithm was verified using MATLAB simulations and practical measurements.

Keywords

  • ADC testing
  • sine wave testing
  • frequency selection
  • windowed DFT
  • aliasing
access type Open Access

Impedance Method for Leak Detection in Zigzag Pipelines

Published Online: 20 Jan 2011
Page range: 209 - 213

Abstract

Impedance Method for Leak Detection in Zigzag Pipelines

Transportation of liquids is a primary aspect of human life. The most important infrastructure used accordingly is the pipeline. It serves as an asset for transporting different liquids and strategic goods. The latter are for example: chemical substances, oil, gas and water. Thus, it is necessary to monitor such infrastructures by means of specific tools. Leakage detection methods are used to reveal liquid leaks in pipelines for many applications, namely, waterworks, oil pipelines, industry heat exchangers, etc. The configuration of pipelines is a key issue because it impacts on the effectiveness of the method to be used and, consequently, on the results to be counterchecked. This research illustrated an improvement of the impedance method for zigzag pipeline by carrying out an experimental frequency analysis that has been compared with other methods based on frequency response. Hence, the impedance method is generally used for simple (straight) pipeline configurations because complicated pipelines with many curves introduce difficulties and major uncertainties in the calculation of characteristic impedance and in the statement of boundary conditions. The paper illustrates the case of a water pipeline where the leakage is acquired thanks to pressure transducers.

Keywords

  • Pipeline leak detection
  • magnetic sensors
  • impedance method
  • transient analysis
  • pressure transducers
6 Articles
access type Open Access

Model Based Determination of Detection Limits for Proton Transfer Reaction Mass Spectrometer

Published Online: 20 Jan 2011
Page range: 180 - 188

Abstract

Model Based Determination of Detection Limits for Proton Transfer Reaction Mass Spectrometer

Proton Transfer Reaction Mass Spectrometry (PTR-MS) is a chemical ionization mass spectrometric technique which allows to measure trace gases as, for example, in exhaled human breath. The quantification of compounds at low concentrations is desirable for medical diagnostics. Typically, an increase of measuring accuracy can be achieved if the duration of the measuring process is extended. For real time measurements the time windows for measurement are relatively short, in order to get a good time resolution (e.g. with breath-to-breath resolution during exercise on a stationary bicycle). Determination of statistical detection limits is typically based on calibration measurements, but this approach is limited, especially for very low concentrations. To overcome this problem, a calculation of limit of quantification (LOQ) and limit of detection (LOD), respectively, based on a theoretical model of the measurement process is outlined.

Keywords

  • Detection limits
  • limit of quantification
  • limit of detection
  • mass spectrometry
  • PTR-MS
access type Open Access

Estimation and Tracking of the Power Quality Disturbances in the Frequency Domain

Published Online: 20 Jan 2011
Page range: 189 - 194

Abstract

Estimation and Tracking of the Power Quality Disturbances in the Frequency Domain

In this paper, simple algorithms for fast measurement and estimation of the unknown changing frequency, amplitude, and phase difference of the sinusoidal signals from two channels with the same frequency, as well as other parameters for evaluation of the power quality disturbances, are presented. Parameters are calculated from the DFT coefficients around the component peaks. The improvement for reducing the influences of the harmonic components is the estimation with the three-point interpolation and the Hann window.

Keywords

  • Power quality
  • voltage quality
  • disturbance estimation
  • frequency domain
  • non-coherency
access type Open Access

Modelling and Simulation of the Pyroelectric Detector Using MATLAB/Simulink

Published Online: 20 Jan 2011
Page range: 195 - 199

Abstract

Modelling and Simulation of the Pyroelectric Detector Using MATLAB/Simulink

An attempt was made to obtain a simple Laplace transfer function model of a pyroelectric detector which would make an excellent basis for the analysis of its dynamic behaviour. Knowledge of the transfer function model of the pyroelectric detector is necessary for its simulation studies in MATLAB/Simulink environment. A simple model of the pyroelectric detector was implemented in MATLAB/Simulink and some exemplary results of investigation of its voltage response to incident radiation and frequency characteristics were presented.

Keywords

  • modelling of pyroelectric detector
  • transfer function model of pyroelectric detector
  • simulation of pyroelectric detector
access type Open Access

Traceability of Voltage Measurements for Non-Sinusoidal Waveforms

Published Online: 20 Jan 2011
Page range: 200 - 204

Abstract

Traceability of Voltage Measurements for Non-Sinusoidal Waveforms

This paper describes the result of work performed at the Laboratoire National de Métrologie et d'Essais (LNE) aiming at developing a standard system to measure RMS value and harmonic contents of distorted voltage waveforms by means of a sampling voltmeter. Thermal converters are used to trace the RMS value to the SI units. The error of the DVM has been generally found less than 10 μV/V up to 2 kHz but can reach about 50 μV/V at 2.5 kHz for RMS voltage measurements for sine waves. For distorted waveforms, deviations within 15 μV/V have been obtained whatever the total harmonic distortion of the waveforms.

Keywords

  • distorted voltage waveforms
  • thermal converters
  • sampling techniques
  • analog to digital converters
access type Open Access

Frequency Selection of Sine Wave for Dynamic ADC Test

Published Online: 20 Jan 2011
Page range: 205 - 208

Abstract

Frequency Selection of Sine Wave for Dynamic ADC Test

The paper deals with determination of an optimum frequency for the time domain and frequency domain ADC testing. Proposed algorithm for selection of test signal frequency fulfills two common requirements. The first requirement is to get maximum quantity of distinct phases of the sampled values which are uniformly distributed between 0 and 2π; the second one is to avoid overlapping of higher harmonic components aliased in the first Nyquist zone. The algorithm was verified using MATLAB simulations and practical measurements.

Keywords

  • ADC testing
  • sine wave testing
  • frequency selection
  • windowed DFT
  • aliasing
access type Open Access

Impedance Method for Leak Detection in Zigzag Pipelines

Published Online: 20 Jan 2011
Page range: 209 - 213

Abstract

Impedance Method for Leak Detection in Zigzag Pipelines

Transportation of liquids is a primary aspect of human life. The most important infrastructure used accordingly is the pipeline. It serves as an asset for transporting different liquids and strategic goods. The latter are for example: chemical substances, oil, gas and water. Thus, it is necessary to monitor such infrastructures by means of specific tools. Leakage detection methods are used to reveal liquid leaks in pipelines for many applications, namely, waterworks, oil pipelines, industry heat exchangers, etc. The configuration of pipelines is a key issue because it impacts on the effectiveness of the method to be used and, consequently, on the results to be counterchecked. This research illustrated an improvement of the impedance method for zigzag pipeline by carrying out an experimental frequency analysis that has been compared with other methods based on frequency response. Hence, the impedance method is generally used for simple (straight) pipeline configurations because complicated pipelines with many curves introduce difficulties and major uncertainties in the calculation of characteristic impedance and in the statement of boundary conditions. The paper illustrates the case of a water pipeline where the leakage is acquired thanks to pressure transducers.

Keywords

  • Pipeline leak detection
  • magnetic sensors
  • impedance method
  • transient analysis
  • pressure transducers

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