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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 12 (2012): Issue 5 (October 2012)

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

Search

7 Articles
access type Open Access

Validation test of a cam mover based micrometric pre-alignment system for future accelerator components

Published Online: 21 Oct 2012
Page range: 162 - 167

Abstract

Abstract

Compact Linear Collider (CLIC) is a 48 km long linear accelerator currently studied at CERN. It is a high luminosity electronpositron collider with an energy range of 0.5-3 TeV. CLIC is based on a two-beam technology in which a high current drive beam transfers RF power to the main beam accelerating structures. The main beam is steered with quadrupole magnets. Main beam components have to be actively pre-aligned within 14 μm in sliding windows of 200 m. To reach the pre-alignment requirement as well as the rigidity required by nano-stabilization, a system based on eccentric cam movers is proposed for the re-adjustment of the main beam quadrupoles. Validation of the technique to the stringent CLIC requirements was started with tests in one degree of freedom on an eccentric cam mover. This paper describes the dedicated mock-up as well as the tests and measurements carried out with it. Finally, the test results are presented

Keywords

  • CLIC
  • main beam quadrupole
  • eccentric cam mover
  • alignment
access type Open Access

Performance Evaluation of Neural Network Based Pulse-Echo Weld Defect Classifiers

Published Online: 21 Oct 2012
Page range: 168 - 174

Abstract

Abstract

Pulse-echo ultrasonic signal is used to detect weld defects with high probability. However, utilizing echo signal for defects classification is another issue that has attracted attention of many researchers who have devised algorithms and tested them against their own databases. In this paper, a study is conducted to score the performance of various algorithms against a single echo signal database. Algorithms tested the use of Wavelet Transform (WT), Fast Fourier Transform (FFT) and time domain echo signal features and employed several NN’s architectures such as Multi-Layer Perceptron Neural Network (MLP), Self Organizing Map (SOM) and others known to be good classifiers. The average performance of all can be viewed fair (90%) while some algorithms render success rate of about 94%. It seems that acquiring higher success rates out of a single fixed angle probe pulseecho set up needs new arrangements of data collection, which is under investigation.

Keywords

  • Nondestructive testing
  • Pulse-Echo ultrasonic
  • neural network
  • radial basis function
  • self organizing map
  • Wavelet Transform
access type Open Access

Frequency and parameter estimation of multi-sinusoidal signal

Published Online: 21 Oct 2012
Page range: 175 - 183

Abstract

Abstract

Estimating the fundamental frequency and harmonic parameters is basic for signal modeling in a power supply system. This paper presents a complexity-reduced algorithm for signal reconstruction in the time domain from irregularly spaced sampling values. Differing from the existing parameter estimation algorithms, either in power quality monitoring or in harmonic compensation, the proposed algorithm enables a simultaneous estimation of the fundamental frequency, the amplitudes and phases of harmonic waves. The reduction in complexity is achieved owing to completely new analytical and summarized expressions that enable a quick estimation at a low numerical error. It is proved that the estimation performance of the proposed algorithm can attain Cramer-Rao lower bound (CRLB) for sufficiently high signal-to-noise ratios. The proposed algorithm can be applied in signal reconstruction, spectral estimation, system identification, as well as in other important signal processing problems. The simulation and experimental results verify the effectiveness of the proposed algorithm.

  • Band-limited signals
  • fundamental frequency and Fourier coefficient estimation
  • analytical solutions
  • signal reconstruction
  • time domain

Keywords:

  • Band-limited signals
  • fundamental frequency and Fourier coefficient estimation
  • analytical solutions
  • signal reconstruction
  • time domain
access type Open Access

Non-contact method for surface roughness measurement after machining

Published Online: 21 Oct 2012
Page range: 184 - 188

Abstract

Abstract

The paper deals with the measurement and identification of surfaces after machining in a non-contact manner. It presents a new modified measurement method and its implementation, the results of intensity distribution in the defocusing plane, their analysis and interpretation. The scanned intensity distribution at the defocusing plane gives information necessary to assess the second derivatives, and thus, surface functions which can be used to determine groove curvatures of the real surface morphology. The proposed method of measurement has proved to be very sensitive in evaluating the differences between surface finishing methods by which the measured surface standards (etalons) were machined. Two methods of machining were chosen: face grinding and planning. By comparing the roughness standard values Ra, there were obtained relationships between these values and the parameter of the characteristic frequency of vertical inequality being measured according to the presented method. A good correlation between the measured and surface standard values with the correlation coefficient taking a range of values from 0.8 to 1 was achieved.

  • Surface roughness
  • non-contact measurement
  • surface finishing methods

Keywords:

  • Surface roughness
  • non-contact measurement
  • surface finishing methods
access type Open Access

Design of MEMS accelerometer based acceleration measurement system for automobiles

Published Online: 21 Oct 2012
Page range: 189 - 194

Abstract

Abstract

Design of an acceleration measurement system using a MEMS accelerometer to measure acceleration of automobiles in all the three axes is presented. Electronic stability control and anti-lock breaking systems in automobiles use the acceleration measurements to offer safety in driving. The system uses an ARM microcontroller to quantize the outputs of accelerometer and save the measurement data on a microSD card. A LabVIEW program has been developed to analyze the longitudinal acceleration measurement data and test the measurement system. Random noises generated and added with measurement data during measurement are filtered by a Kalman filter implemented in LabVIEW. Longitudinal velocity of the vehicle is computed from the measurement data and displayed on a graphical chart. Typical measurement of velocity of a vehicle at different accelerations and decelerations is presented.

  • MEMS Accelerometer
  • acceleration measurement
  • ARM microcontroller
  • LabVIEW
  • Kalman filter

Keywords:

  • MEMS Accelerometer
  • acceleration measurement
  • ARM microcontroller
  • LabVIEW
  • Kalman filter
access type Open Access

A new method for the prediction of laser cut surface topography

Published Online: 21 Oct 2012
Page range: 195 - 204

Abstract

Abstract

The submitted contribution focuses on the clarification of a laser beam cutting technology especially from the point of view of created surface topography. It provides a new view on a deformation process caused by laser beam action and on possibilities of using the surface topography. The measurement and characterisation of surface topography was performed in depth traces using a contact profilometer Surftest SJ 401 and by and an optical-contact profilometer Talysurf CLI 2000 (measured from the top edge of the sample). Thanks to this procedure, it was possible to observe and to measure a development of the numerical values of the surface (profile) roughness parameter Ra. Based on the measurement of the surface topography, there were analyzed and interpreted data with a purpose to theoretically describe surface topography and to develop an analytical solution for the profile topographical function. By using the profile topographical function, it is possible to solve the practical problems the most engineers and users face in laser beam cutting technology (LBC) process, as well as to maximize LBC manufacturing system performance and to determine the values of the process parameters that will reach the desired product quality.

  • Laser cutting
  • surface topography
  • prediction
  • deformation parameters
  • topographic function

Keywords:

  • Laser cutting
  • surface topography
  • prediction
  • deformation parameters
  • topographic function
access type Open Access

Diffusion MRI: mitigation of magnetic field inhomogeneities

Published Online: 21 Oct 2012
Page range: 205 - 212

Abstract

Abstract

The article reports on certain artifacts that emerge during the in vitro diffusion-weighted imaging of physical samples. In this context, the authors analyze the influence of magnetic field inhomogeneity, temperature, or eddy currents and consider artifact mitigation procedures. A technique reducing the examined spurious effects was designed, experimentally verified, and denominated as the three measurement method. The technique proved to be useful mainly for the evaluation of a DWI image measured with a diffusion gradient in the z axis, where the relative measurement error decreased to 3.38 % (during measurement using two images, the relative error was greater than 19 %). For small errors within the measurement of diffusion constants of a deionized water sample (< 5 %) it was necessary to select a b-factor value larger than 200·106 s.m-2. Temperature stabilization with accuracy better than 0.1 °C during the entire measuring process is a necessary prerequisite for the measurement of biological or material samples with relative accuracy lower than 1 %.

  • Correction
  • diffusion
  • inhomogeneity
  • eddy currents
  • magnetic resonance

Keywords:

  • Correction
  • diffusion
  • inhomogeneity
  • eddy currents
  • magnetic resonance
7 Articles
access type Open Access

Validation test of a cam mover based micrometric pre-alignment system for future accelerator components

Published Online: 21 Oct 2012
Page range: 162 - 167

Abstract

Abstract

Compact Linear Collider (CLIC) is a 48 km long linear accelerator currently studied at CERN. It is a high luminosity electronpositron collider with an energy range of 0.5-3 TeV. CLIC is based on a two-beam technology in which a high current drive beam transfers RF power to the main beam accelerating structures. The main beam is steered with quadrupole magnets. Main beam components have to be actively pre-aligned within 14 μm in sliding windows of 200 m. To reach the pre-alignment requirement as well as the rigidity required by nano-stabilization, a system based on eccentric cam movers is proposed for the re-adjustment of the main beam quadrupoles. Validation of the technique to the stringent CLIC requirements was started with tests in one degree of freedom on an eccentric cam mover. This paper describes the dedicated mock-up as well as the tests and measurements carried out with it. Finally, the test results are presented

Keywords

  • CLIC
  • main beam quadrupole
  • eccentric cam mover
  • alignment
access type Open Access

Performance Evaluation of Neural Network Based Pulse-Echo Weld Defect Classifiers

Published Online: 21 Oct 2012
Page range: 168 - 174

Abstract

Abstract

Pulse-echo ultrasonic signal is used to detect weld defects with high probability. However, utilizing echo signal for defects classification is another issue that has attracted attention of many researchers who have devised algorithms and tested them against their own databases. In this paper, a study is conducted to score the performance of various algorithms against a single echo signal database. Algorithms tested the use of Wavelet Transform (WT), Fast Fourier Transform (FFT) and time domain echo signal features and employed several NN’s architectures such as Multi-Layer Perceptron Neural Network (MLP), Self Organizing Map (SOM) and others known to be good classifiers. The average performance of all can be viewed fair (90%) while some algorithms render success rate of about 94%. It seems that acquiring higher success rates out of a single fixed angle probe pulseecho set up needs new arrangements of data collection, which is under investigation.

Keywords

  • Nondestructive testing
  • Pulse-Echo ultrasonic
  • neural network
  • radial basis function
  • self organizing map
  • Wavelet Transform
access type Open Access

Frequency and parameter estimation of multi-sinusoidal signal

Published Online: 21 Oct 2012
Page range: 175 - 183

Abstract

Abstract

Estimating the fundamental frequency and harmonic parameters is basic for signal modeling in a power supply system. This paper presents a complexity-reduced algorithm for signal reconstruction in the time domain from irregularly spaced sampling values. Differing from the existing parameter estimation algorithms, either in power quality monitoring or in harmonic compensation, the proposed algorithm enables a simultaneous estimation of the fundamental frequency, the amplitudes and phases of harmonic waves. The reduction in complexity is achieved owing to completely new analytical and summarized expressions that enable a quick estimation at a low numerical error. It is proved that the estimation performance of the proposed algorithm can attain Cramer-Rao lower bound (CRLB) for sufficiently high signal-to-noise ratios. The proposed algorithm can be applied in signal reconstruction, spectral estimation, system identification, as well as in other important signal processing problems. The simulation and experimental results verify the effectiveness of the proposed algorithm.

  • Band-limited signals
  • fundamental frequency and Fourier coefficient estimation
  • analytical solutions
  • signal reconstruction
  • time domain

Keywords:

  • Band-limited signals
  • fundamental frequency and Fourier coefficient estimation
  • analytical solutions
  • signal reconstruction
  • time domain
access type Open Access

Non-contact method for surface roughness measurement after machining

Published Online: 21 Oct 2012
Page range: 184 - 188

Abstract

Abstract

The paper deals with the measurement and identification of surfaces after machining in a non-contact manner. It presents a new modified measurement method and its implementation, the results of intensity distribution in the defocusing plane, their analysis and interpretation. The scanned intensity distribution at the defocusing plane gives information necessary to assess the second derivatives, and thus, surface functions which can be used to determine groove curvatures of the real surface morphology. The proposed method of measurement has proved to be very sensitive in evaluating the differences between surface finishing methods by which the measured surface standards (etalons) were machined. Two methods of machining were chosen: face grinding and planning. By comparing the roughness standard values Ra, there were obtained relationships between these values and the parameter of the characteristic frequency of vertical inequality being measured according to the presented method. A good correlation between the measured and surface standard values with the correlation coefficient taking a range of values from 0.8 to 1 was achieved.

  • Surface roughness
  • non-contact measurement
  • surface finishing methods

Keywords:

  • Surface roughness
  • non-contact measurement
  • surface finishing methods
access type Open Access

Design of MEMS accelerometer based acceleration measurement system for automobiles

Published Online: 21 Oct 2012
Page range: 189 - 194

Abstract

Abstract

Design of an acceleration measurement system using a MEMS accelerometer to measure acceleration of automobiles in all the three axes is presented. Electronic stability control and anti-lock breaking systems in automobiles use the acceleration measurements to offer safety in driving. The system uses an ARM microcontroller to quantize the outputs of accelerometer and save the measurement data on a microSD card. A LabVIEW program has been developed to analyze the longitudinal acceleration measurement data and test the measurement system. Random noises generated and added with measurement data during measurement are filtered by a Kalman filter implemented in LabVIEW. Longitudinal velocity of the vehicle is computed from the measurement data and displayed on a graphical chart. Typical measurement of velocity of a vehicle at different accelerations and decelerations is presented.

  • MEMS Accelerometer
  • acceleration measurement
  • ARM microcontroller
  • LabVIEW
  • Kalman filter

Keywords:

  • MEMS Accelerometer
  • acceleration measurement
  • ARM microcontroller
  • LabVIEW
  • Kalman filter
access type Open Access

A new method for the prediction of laser cut surface topography

Published Online: 21 Oct 2012
Page range: 195 - 204

Abstract

Abstract

The submitted contribution focuses on the clarification of a laser beam cutting technology especially from the point of view of created surface topography. It provides a new view on a deformation process caused by laser beam action and on possibilities of using the surface topography. The measurement and characterisation of surface topography was performed in depth traces using a contact profilometer Surftest SJ 401 and by and an optical-contact profilometer Talysurf CLI 2000 (measured from the top edge of the sample). Thanks to this procedure, it was possible to observe and to measure a development of the numerical values of the surface (profile) roughness parameter Ra. Based on the measurement of the surface topography, there were analyzed and interpreted data with a purpose to theoretically describe surface topography and to develop an analytical solution for the profile topographical function. By using the profile topographical function, it is possible to solve the practical problems the most engineers and users face in laser beam cutting technology (LBC) process, as well as to maximize LBC manufacturing system performance and to determine the values of the process parameters that will reach the desired product quality.

  • Laser cutting
  • surface topography
  • prediction
  • deformation parameters
  • topographic function

Keywords:

  • Laser cutting
  • surface topography
  • prediction
  • deformation parameters
  • topographic function
access type Open Access

Diffusion MRI: mitigation of magnetic field inhomogeneities

Published Online: 21 Oct 2012
Page range: 205 - 212

Abstract

Abstract

The article reports on certain artifacts that emerge during the in vitro diffusion-weighted imaging of physical samples. In this context, the authors analyze the influence of magnetic field inhomogeneity, temperature, or eddy currents and consider artifact mitigation procedures. A technique reducing the examined spurious effects was designed, experimentally verified, and denominated as the three measurement method. The technique proved to be useful mainly for the evaluation of a DWI image measured with a diffusion gradient in the z axis, where the relative measurement error decreased to 3.38 % (during measurement using two images, the relative error was greater than 19 %). For small errors within the measurement of diffusion constants of a deionized water sample (< 5 %) it was necessary to select a b-factor value larger than 200·106 s.m-2. Temperature stabilization with accuracy better than 0.1 °C during the entire measuring process is a necessary prerequisite for the measurement of biological or material samples with relative accuracy lower than 1 %.

  • Correction
  • diffusion
  • inhomogeneity
  • eddy currents
  • magnetic resonance

Keywords:

  • Correction
  • diffusion
  • inhomogeneity
  • eddy currents
  • magnetic resonance

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