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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 4 (August 2012)

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

Design of Experiment for Measurement of Langevin Function

Published Online: 13 Aug 2012
Page range: 121 - 127

Abstract

Design of Experiment for Measurement of Langevin Function

The presented study focuses on a confrontation of the theory of regression models and theory of experiment with the real situation of determining properties of magnetic (nano)materials. Their magnetic properties can be deduced by measuring their magnetization, being the fundamental magnetic quantity of an arbitrary (nano)material. The results of the magnetization measurements determine the unknown parameters of a known nonlinear function that characterizes the (nano)material under investigation. Knowledge of the values of the uknkown parameters enables to decide whether the (nano)material is suitable or not for a particular application. Thus, in this work, we present a possible approach how to estimate the unknown parameters of the nonlinear function by the regression models, taking into account a relevant linearization criterion. Then, we suggest an appropriate design for the measurement to get better estimators of the parameters.

Keywords

  • Approximation
  • nonlinear regression models
  • linearization
  • BLUE
  • D-optimal design of experiment
  • nanomaterial
  • hysteresis loop
  • Langevin function
Open Access

Analysis of ATE Measurability Using Information Flow Model

Published Online: 13 Aug 2012
Page range: 128 - 132

Abstract

Analysis of ATE Measurability Using Information Flow Model

Since many test equipments can't be calibrated conveniently, this paper proposed a new concept named measurability to solve the problem. The measurability is defined, and its indexes are given in detail. Selected from the models of testability, the information flow model is used to analyze the ATE (automatic test equipment) measurability. The correlative matrix of information flow model is decided according to the trace chain. Finally, a practical example is given to show the analysis process.

Keywords

  • ATE
  • measurability analysis
  • information flow model
  • correlative matrix
Open Access

Treatment of Experimental Data with Discordant Observations: Issues in Empirical Identification of Distribution

Published Online: 13 Aug 2012
Page range: 133 - 140

Abstract

Treatment of Experimental Data with Discordant Observations: Issues in Empirical Identification of Distribution

Performances of several methods currently used for detection of discordant observations are reviewed, considering a set of absolute measurements of gravity acceleration exhibiting some peculiar features. Along with currently used methods, a criterion based upon distribution of extremes is also relied upon to provide references; a modification of a simple, broadly used method is mentioned, improving performances while retaining inherent ease of use. Identification of distributions underlying experimental data may entail a substantial uncertainty component, particularly when sample size is small, and no mechanistic models are available. A pragmatic approach is described, providing estimation to a first approximation of overall uncertainty, covering both estimation of parameters, and identification of distribution shape.

Keywords

  • Distribution shape
  • outlier
  • uncertainty
  • confidence region
  • gravimetry
Open Access

Radial Ball Bearing Inner Race Defect Width Measurement using Analytical Wavelet Transform of Acoustic and Vibration Signal

Published Online: 13 Aug 2012
Page range: 141 - 148

Abstract

Radial Ball Bearing Inner Race Defect Width Measurement using Analytical Wavelet Transform of Acoustic and Vibration Signal

In the present work, an experiment is carried out with a customized test setup where the seeded defects are introduced in the form of an axial groove on the inner race of a radial ball bearing. The nature of the acoustic and vibration signal bursts, and their correlation with the inner race defects, are established and estimated. Experimental investigation reveals that the analytical wavelet transform (AWT) is an effective tool for analyzing the acoustic and vibration signals, transmitted from the bearing, in order to characterize and measure the defect size. In the recent work, AWT followed by the time marginal integration (TMI) have been implemented on acoustic and vibration signals of a defective radial bearing. Size of the defect in the inner race of bearing is corroborated well with AWT scalogram. The segregation of the defect is carried out on TMI graph across the highest amplitude spike, which is due to signal burst (due to a contact of ball with bearing inner race defect). This manual demarcation on TMI graph in time axis provides the time duration (contact between a ball and the inner race defect). Using this time duration of the ball passed over bearing inner race defect, RPM of shaft mounted across bearing, and the fundamental train frequency, the defect width is estimated. The deviation of the measured width from the actual, using the proposed method, is sought below 5%. Summarizing, the proposed method can be reckoned a suitable and reliable measurement of radial bearing inner race defect width from acoustic and vibration signal.

Keywords

  • Condition Monitoring
  • Analytical Wavelet Transform
  • Scalogram
  • Time Marginal Integration (TMI)
Open Access

Long Term Uncertainty Investigations of 1 MN Force Calibration Machine at NPL, India (NPLI)

Published Online: 13 Aug 2012
Page range: 149 - 152

Abstract

Long Term Uncertainty Investigations of 1 MN Force Calibration Machine at NPL, India (NPLI)

The present paper is an attempt to study the long term uncertainty of 1 MN hydraulic multiplication system (HMS) force calibration machine (FCM) at the National Physical Laboratory, India (NPLI), which is used for calibration of the force measuring instruments in the range of 100 kN - 1 MN. The 1 MN HMS FCM was installed at NPLI in 1993 and was built on the principle of hydraulic amplifications of dead weights. The best measurement capability (BMC) of the machine is ± 0.025% (k = 2) and it is traceable to national standards by means of precision force transfer standards (FTS). The present study discusses the uncertainty variations of the 1 MN HMS FCM over the years and describes the other parameters in detail, too. The 1 MN HMS FCM was calibrated in the years 2004, 2006, 2007, 2008, 2009 and 2010 and the results have been reported.

Keywords

  • Force standard machine (FSM)
  • force calibration machine (FCM)
  • hydraulic multiplication system (HMS)
  • best measurement capability (BMC)
  • dead weights
  • uncertainty of measurement
Open Access

Soft-tissues Image Processing: Comparison of Traditional Segmentation Methods with 2D active Contour Methods

Published Online: 13 Aug 2012
Page range: 153 - 161

Abstract

Soft-tissues Image Processing: Comparison of Traditional Segmentation Methods with 2D active Contour Methods

The paper deals with modern methods of image processing, especially image segmentation, classification and evaluation of parameters. It focuses primarily on processing medical images of soft tissues obtained by magnetic resonance tomography (MR). It is easy to describe edges of the sought objects using segmented images. The edges found can be useful for further processing of monitored object such as calculating the perimeter, surface and volume evaluation or even three-dimensional shape reconstruction. The proposed solutions can be used for the classification of healthy/unhealthy tissues in MR or other imaging. Application examples of the proposed segmentation methods are shown. Research in the area of image segmentation focuses on methods based on solving partial differential equations. This is a modern method for image processing, often called the active contour method. It is of great advantage in the segmentation of real images degraded by noise with fuzzy edges and transitions between objects. In the paper, results of the segmentation of medical images by the active contour method are compared with results of the segmentation by other existing methods. Experimental applications which demonstrate the very good properties of the active contour method are given.

Keywords

  • Medical image processing
  • image segmentation
  • liver tumor
  • temporomandibular joint disc
  • watershed method
6 Articles
Open Access

Design of Experiment for Measurement of Langevin Function

Published Online: 13 Aug 2012
Page range: 121 - 127

Abstract

Design of Experiment for Measurement of Langevin Function

The presented study focuses on a confrontation of the theory of regression models and theory of experiment with the real situation of determining properties of magnetic (nano)materials. Their magnetic properties can be deduced by measuring their magnetization, being the fundamental magnetic quantity of an arbitrary (nano)material. The results of the magnetization measurements determine the unknown parameters of a known nonlinear function that characterizes the (nano)material under investigation. Knowledge of the values of the uknkown parameters enables to decide whether the (nano)material is suitable or not for a particular application. Thus, in this work, we present a possible approach how to estimate the unknown parameters of the nonlinear function by the regression models, taking into account a relevant linearization criterion. Then, we suggest an appropriate design for the measurement to get better estimators of the parameters.

Keywords

  • Approximation
  • nonlinear regression models
  • linearization
  • BLUE
  • D-optimal design of experiment
  • nanomaterial
  • hysteresis loop
  • Langevin function
Open Access

Analysis of ATE Measurability Using Information Flow Model

Published Online: 13 Aug 2012
Page range: 128 - 132

Abstract

Analysis of ATE Measurability Using Information Flow Model

Since many test equipments can't be calibrated conveniently, this paper proposed a new concept named measurability to solve the problem. The measurability is defined, and its indexes are given in detail. Selected from the models of testability, the information flow model is used to analyze the ATE (automatic test equipment) measurability. The correlative matrix of information flow model is decided according to the trace chain. Finally, a practical example is given to show the analysis process.

Keywords

  • ATE
  • measurability analysis
  • information flow model
  • correlative matrix
Open Access

Treatment of Experimental Data with Discordant Observations: Issues in Empirical Identification of Distribution

Published Online: 13 Aug 2012
Page range: 133 - 140

Abstract

Treatment of Experimental Data with Discordant Observations: Issues in Empirical Identification of Distribution

Performances of several methods currently used for detection of discordant observations are reviewed, considering a set of absolute measurements of gravity acceleration exhibiting some peculiar features. Along with currently used methods, a criterion based upon distribution of extremes is also relied upon to provide references; a modification of a simple, broadly used method is mentioned, improving performances while retaining inherent ease of use. Identification of distributions underlying experimental data may entail a substantial uncertainty component, particularly when sample size is small, and no mechanistic models are available. A pragmatic approach is described, providing estimation to a first approximation of overall uncertainty, covering both estimation of parameters, and identification of distribution shape.

Keywords

  • Distribution shape
  • outlier
  • uncertainty
  • confidence region
  • gravimetry
Open Access

Radial Ball Bearing Inner Race Defect Width Measurement using Analytical Wavelet Transform of Acoustic and Vibration Signal

Published Online: 13 Aug 2012
Page range: 141 - 148

Abstract

Radial Ball Bearing Inner Race Defect Width Measurement using Analytical Wavelet Transform of Acoustic and Vibration Signal

In the present work, an experiment is carried out with a customized test setup where the seeded defects are introduced in the form of an axial groove on the inner race of a radial ball bearing. The nature of the acoustic and vibration signal bursts, and their correlation with the inner race defects, are established and estimated. Experimental investigation reveals that the analytical wavelet transform (AWT) is an effective tool for analyzing the acoustic and vibration signals, transmitted from the bearing, in order to characterize and measure the defect size. In the recent work, AWT followed by the time marginal integration (TMI) have been implemented on acoustic and vibration signals of a defective radial bearing. Size of the defect in the inner race of bearing is corroborated well with AWT scalogram. The segregation of the defect is carried out on TMI graph across the highest amplitude spike, which is due to signal burst (due to a contact of ball with bearing inner race defect). This manual demarcation on TMI graph in time axis provides the time duration (contact between a ball and the inner race defect). Using this time duration of the ball passed over bearing inner race defect, RPM of shaft mounted across bearing, and the fundamental train frequency, the defect width is estimated. The deviation of the measured width from the actual, using the proposed method, is sought below 5%. Summarizing, the proposed method can be reckoned a suitable and reliable measurement of radial bearing inner race defect width from acoustic and vibration signal.

Keywords

  • Condition Monitoring
  • Analytical Wavelet Transform
  • Scalogram
  • Time Marginal Integration (TMI)
Open Access

Long Term Uncertainty Investigations of 1 MN Force Calibration Machine at NPL, India (NPLI)

Published Online: 13 Aug 2012
Page range: 149 - 152

Abstract

Long Term Uncertainty Investigations of 1 MN Force Calibration Machine at NPL, India (NPLI)

The present paper is an attempt to study the long term uncertainty of 1 MN hydraulic multiplication system (HMS) force calibration machine (FCM) at the National Physical Laboratory, India (NPLI), which is used for calibration of the force measuring instruments in the range of 100 kN - 1 MN. The 1 MN HMS FCM was installed at NPLI in 1993 and was built on the principle of hydraulic amplifications of dead weights. The best measurement capability (BMC) of the machine is ± 0.025% (k = 2) and it is traceable to national standards by means of precision force transfer standards (FTS). The present study discusses the uncertainty variations of the 1 MN HMS FCM over the years and describes the other parameters in detail, too. The 1 MN HMS FCM was calibrated in the years 2004, 2006, 2007, 2008, 2009 and 2010 and the results have been reported.

Keywords

  • Force standard machine (FSM)
  • force calibration machine (FCM)
  • hydraulic multiplication system (HMS)
  • best measurement capability (BMC)
  • dead weights
  • uncertainty of measurement
Open Access

Soft-tissues Image Processing: Comparison of Traditional Segmentation Methods with 2D active Contour Methods

Published Online: 13 Aug 2012
Page range: 153 - 161

Abstract

Soft-tissues Image Processing: Comparison of Traditional Segmentation Methods with 2D active Contour Methods

The paper deals with modern methods of image processing, especially image segmentation, classification and evaluation of parameters. It focuses primarily on processing medical images of soft tissues obtained by magnetic resonance tomography (MR). It is easy to describe edges of the sought objects using segmented images. The edges found can be useful for further processing of monitored object such as calculating the perimeter, surface and volume evaluation or even three-dimensional shape reconstruction. The proposed solutions can be used for the classification of healthy/unhealthy tissues in MR or other imaging. Application examples of the proposed segmentation methods are shown. Research in the area of image segmentation focuses on methods based on solving partial differential equations. This is a modern method for image processing, often called the active contour method. It is of great advantage in the segmentation of real images degraded by noise with fuzzy edges and transitions between objects. In the paper, results of the segmentation of medical images by the active contour method are compared with results of the segmentation by other existing methods. Experimental applications which demonstrate the very good properties of the active contour method are given.

Keywords

  • Medical image processing
  • image segmentation
  • liver tumor
  • temporomandibular joint disc
  • watershed method

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