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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 3 (June 2012)

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

MRI Slice Segmentation and 3D Modelling of Temporomandibular Joint Measured by Microscopic Coil

Published Online: 28 May 2012
Page range: 74 - 81

Abstract

MRI Slice Segmentation and 3D Modelling of Temporomandibular Joint Measured by Microscopic Coil

The paper focuses on the segmentation of magnetic resonance imaging (MRI) slices and 3D modelling of the temporomandibular joint disc in order to help physicians diagnose patients with dysfunction of the temporomandibular joint (TMJ). The TMJ is one of the most complex joints in the human body. The most common joint dysfunction is due to the disc. The disc is a soft tissue, which in principle cannot be diagnosed by the CT method. Therefore, a 3D model is made from the MRI slices, which can image soft tissues. For the segmentation of the disc in individual slices a new method is developed based on spatial distribution and anatomical TMJ structure with automatic thresholding. The thresholding is controlled by a genetic algorithm. The 3D model is realized using the marching cube method.

Keywords

  • Marching cubes
  • genetic algorithms
  • magnetic resonance imaging
  • Iso-surfaces
  • 3D models
access type Open Access

Application of Linear Discriminant Analysis in Dimensionality Reduction for Hand Motion Classification

Published Online: 28 May 2012
Page range: 82 - 89

Abstract

Application of Linear Discriminant Analysis in Dimensionality Reduction for Hand Motion Classification

The classification of upper-limb movements based on surface electromyography (EMG) signals is an important issue in the control of assistive devices and rehabilitation systems. Increasing the number of EMG channels and features in order to increase the number of control commands can yield a high dimensional feature vector. To cope with the accuracy and computation problems associated with high dimensionality, it is commonplace to apply a processing step that transforms the data to a space of significantly lower dimensions with only a limited loss of useful information. Linear discriminant analysis (LDA) has been successfully applied as an EMG feature projection method. Recently, a number of extended LDA-based algorithms have been proposed, which are more competitive in terms of both classification accuracy and computational costs/times with classical LDA. This paper presents the findings of a comparative study of classical LDA and five extended LDA methods. From a quantitative comparison based on seven multi-feature sets, three extended LDA-based algorithms, consisting of uncorrelated LDA, orthogonal LDA and orthogonal fuzzy neighborhood discriminant analysis, produce better class separability when compared with a baseline system (without feature projection), principle component analysis (PCA), and classical LDA. Based on a 7-dimension time domain and time-scale feature vectors, these methods achieved respectively 95.2% and 93.2% classification accuracy by using a linear discriminant classifier.

Keywords

  • Electromyography signal
  • EMG
  • uncorrelated LDA
  • orthogonal LDA
  • orthogonal fuzzy neighborhood discriminant analysis
  • kernel discriminant analysis
  • QR decomposition
  • feature extraction
  • feature projection
access type Open Access

Application of Replica Technique and SEM in Accuracy Measurement of Ceramic Crowns

Published Online: 28 May 2012
Page range: 90 - 97

Abstract

Application of Replica Technique and SEM in Accuracy Measurement of Ceramic Crowns

The paper presents a comparative study of the measuring values of the marginal gap related to the ceramic crowns made by dental CAD/CAM system using the replica technique and SEM. The study was conducted using three experimental groups, which consisted of ceramic crowns manufactured by the Cerec CAD/CAM system. The scanning procedure was carried out using three specialized dental 3D digitization systems from the Cerec family - two types of extraoral optical scanning systems and an intraoral optical scanner. Measurements of the marginal gap were carried out using the replica technique and SEM. The comparison of aggregate values of the marginal gap using the replica technique showed a statistically significant difference between the systems. The measured values of marginal gaps of ceramic crowns using the replica technique were significantly lower compared to those measured by SEM. The results indicate that the choice of technique for measuring the accuracy of ceramic crowns influences the final results of investigation.

Keywords

  • Accuracy
  • CAD/CAM
  • replica technique
  • SEM
  • ceramic crown
access type Open Access

Design, Realization and Experiments with a new RF Head Probe Coil for Human Vocal Tract Imaging in an NMR device

Published Online: 28 May 2012
Page range: 98 - 103

Abstract

Design, Realization and Experiments with a new RF Head Probe Coil for Human Vocal Tract Imaging in an NMR device

Magnetic resonance imaging (MRI) is nowadays widely used in medicine for diagnostic imaging and in research studies. The modeling of the human vocal tract acoustics has recently attracted considerable interest. This paper describes the design, realization and first MR scan experiments with a new head probe coil for vocal tract imaging in the open-air MRI equipment working in a weak magnetic field up to 0.2 T. The paper also describes an experimental setting for sound recording during the MR imaging.

Keywords

  • NMR imaging
  • field calculation
  • RF probe coil
  • vocal tract modeling
access type Open Access

Model-based Estimation for Pose, Velocity of Projectile from Stereo Linear Array Image

Published Online: 28 May 2012
Page range: 104 - 110

Abstract

Model-based Estimation for Pose, Velocity of Projectile from Stereo Linear Array Image

The pose (position and attitude) and velocity of in-flight projectiles have major influence on the performance and accuracy. A cost-effective method for measuring the gun-boosted projectiles is proposed. The method adopts only one linear array image collected by the stereo vision system combining a digital line-scan camera and a mirror near the muzzle. From the projectile's stereo image, the motion parameters (pose and velocity) are acquired by using a model-based optimization algorithm. The algorithm achieves optimal estimation of the parameters by matching the stereo projection of the projectile and that of the same size 3D model. The speed and the AOA (angle of attack) could also be determined subsequently. Experiments are made to test the proposed method.

Keywords

  • Pose
  • velocity
  • projectile
  • speed
  • angle of attack
  • measurement
  • linear array image
access type Open Access

Staged-Fault Testing of Distance Protection Relay Settings

Published Online: 28 May 2012
Page range: 111 - 120

Abstract

Staged-Fault Testing of Distance Protection Relay Settings

In order to analyze the operation of the protection system during induced fault testing in the Croatian power system, a simulation using the CAPE software has been performed. The CAPE software (Computer-Aided Protection Engineering) is expert software intended primarily for relay protection engineers, which calculates current and voltage values during faults in the power system, so that relay protection devices can be properly set up. Once the accuracy of the simulation model had been confirmed, a series of simulations were performed in order to obtain the optimal fault location to test the protection system. The simulation results were used to specify the test sequence definitions for the end-to-end relay testing using advanced testing equipment with GPS synchronization for secondary injection in protection schemes based on communication. The objective of the end-to-end testing was to perform field validation of the protection settings, including verification of the circuit breaker operation, telecommunication channel time and the effectiveness of the relay algorithms. Once the end-to-end secondary injection testing had been completed, the induced fault testing was performed with three-end lines loaded and in service. This paper describes and analyses the test procedure, consisting of CAPE simulations, end-to-end test with advanced secondary equipment and staged-fault test of a three-end power line in the Croatian transmission system.

Keywords

  • Distance protection
  • three-end line
  • Croatian power system
  • protection
  • fault
  • simulation
  • teleprotection scheme
  • communication
6 Articles
access type Open Access

MRI Slice Segmentation and 3D Modelling of Temporomandibular Joint Measured by Microscopic Coil

Published Online: 28 May 2012
Page range: 74 - 81

Abstract

MRI Slice Segmentation and 3D Modelling of Temporomandibular Joint Measured by Microscopic Coil

The paper focuses on the segmentation of magnetic resonance imaging (MRI) slices and 3D modelling of the temporomandibular joint disc in order to help physicians diagnose patients with dysfunction of the temporomandibular joint (TMJ). The TMJ is one of the most complex joints in the human body. The most common joint dysfunction is due to the disc. The disc is a soft tissue, which in principle cannot be diagnosed by the CT method. Therefore, a 3D model is made from the MRI slices, which can image soft tissues. For the segmentation of the disc in individual slices a new method is developed based on spatial distribution and anatomical TMJ structure with automatic thresholding. The thresholding is controlled by a genetic algorithm. The 3D model is realized using the marching cube method.

Keywords

  • Marching cubes
  • genetic algorithms
  • magnetic resonance imaging
  • Iso-surfaces
  • 3D models
access type Open Access

Application of Linear Discriminant Analysis in Dimensionality Reduction for Hand Motion Classification

Published Online: 28 May 2012
Page range: 82 - 89

Abstract

Application of Linear Discriminant Analysis in Dimensionality Reduction for Hand Motion Classification

The classification of upper-limb movements based on surface electromyography (EMG) signals is an important issue in the control of assistive devices and rehabilitation systems. Increasing the number of EMG channels and features in order to increase the number of control commands can yield a high dimensional feature vector. To cope with the accuracy and computation problems associated with high dimensionality, it is commonplace to apply a processing step that transforms the data to a space of significantly lower dimensions with only a limited loss of useful information. Linear discriminant analysis (LDA) has been successfully applied as an EMG feature projection method. Recently, a number of extended LDA-based algorithms have been proposed, which are more competitive in terms of both classification accuracy and computational costs/times with classical LDA. This paper presents the findings of a comparative study of classical LDA and five extended LDA methods. From a quantitative comparison based on seven multi-feature sets, three extended LDA-based algorithms, consisting of uncorrelated LDA, orthogonal LDA and orthogonal fuzzy neighborhood discriminant analysis, produce better class separability when compared with a baseline system (without feature projection), principle component analysis (PCA), and classical LDA. Based on a 7-dimension time domain and time-scale feature vectors, these methods achieved respectively 95.2% and 93.2% classification accuracy by using a linear discriminant classifier.

Keywords

  • Electromyography signal
  • EMG
  • uncorrelated LDA
  • orthogonal LDA
  • orthogonal fuzzy neighborhood discriminant analysis
  • kernel discriminant analysis
  • QR decomposition
  • feature extraction
  • feature projection
access type Open Access

Application of Replica Technique and SEM in Accuracy Measurement of Ceramic Crowns

Published Online: 28 May 2012
Page range: 90 - 97

Abstract

Application of Replica Technique and SEM in Accuracy Measurement of Ceramic Crowns

The paper presents a comparative study of the measuring values of the marginal gap related to the ceramic crowns made by dental CAD/CAM system using the replica technique and SEM. The study was conducted using three experimental groups, which consisted of ceramic crowns manufactured by the Cerec CAD/CAM system. The scanning procedure was carried out using three specialized dental 3D digitization systems from the Cerec family - two types of extraoral optical scanning systems and an intraoral optical scanner. Measurements of the marginal gap were carried out using the replica technique and SEM. The comparison of aggregate values of the marginal gap using the replica technique showed a statistically significant difference between the systems. The measured values of marginal gaps of ceramic crowns using the replica technique were significantly lower compared to those measured by SEM. The results indicate that the choice of technique for measuring the accuracy of ceramic crowns influences the final results of investigation.

Keywords

  • Accuracy
  • CAD/CAM
  • replica technique
  • SEM
  • ceramic crown
access type Open Access

Design, Realization and Experiments with a new RF Head Probe Coil for Human Vocal Tract Imaging in an NMR device

Published Online: 28 May 2012
Page range: 98 - 103

Abstract

Design, Realization and Experiments with a new RF Head Probe Coil for Human Vocal Tract Imaging in an NMR device

Magnetic resonance imaging (MRI) is nowadays widely used in medicine for diagnostic imaging and in research studies. The modeling of the human vocal tract acoustics has recently attracted considerable interest. This paper describes the design, realization and first MR scan experiments with a new head probe coil for vocal tract imaging in the open-air MRI equipment working in a weak magnetic field up to 0.2 T. The paper also describes an experimental setting for sound recording during the MR imaging.

Keywords

  • NMR imaging
  • field calculation
  • RF probe coil
  • vocal tract modeling
access type Open Access

Model-based Estimation for Pose, Velocity of Projectile from Stereo Linear Array Image

Published Online: 28 May 2012
Page range: 104 - 110

Abstract

Model-based Estimation for Pose, Velocity of Projectile from Stereo Linear Array Image

The pose (position and attitude) and velocity of in-flight projectiles have major influence on the performance and accuracy. A cost-effective method for measuring the gun-boosted projectiles is proposed. The method adopts only one linear array image collected by the stereo vision system combining a digital line-scan camera and a mirror near the muzzle. From the projectile's stereo image, the motion parameters (pose and velocity) are acquired by using a model-based optimization algorithm. The algorithm achieves optimal estimation of the parameters by matching the stereo projection of the projectile and that of the same size 3D model. The speed and the AOA (angle of attack) could also be determined subsequently. Experiments are made to test the proposed method.

Keywords

  • Pose
  • velocity
  • projectile
  • speed
  • angle of attack
  • measurement
  • linear array image
access type Open Access

Staged-Fault Testing of Distance Protection Relay Settings

Published Online: 28 May 2012
Page range: 111 - 120

Abstract

Staged-Fault Testing of Distance Protection Relay Settings

In order to analyze the operation of the protection system during induced fault testing in the Croatian power system, a simulation using the CAPE software has been performed. The CAPE software (Computer-Aided Protection Engineering) is expert software intended primarily for relay protection engineers, which calculates current and voltage values during faults in the power system, so that relay protection devices can be properly set up. Once the accuracy of the simulation model had been confirmed, a series of simulations were performed in order to obtain the optimal fault location to test the protection system. The simulation results were used to specify the test sequence definitions for the end-to-end relay testing using advanced testing equipment with GPS synchronization for secondary injection in protection schemes based on communication. The objective of the end-to-end testing was to perform field validation of the protection settings, including verification of the circuit breaker operation, telecommunication channel time and the effectiveness of the relay algorithms. Once the end-to-end secondary injection testing had been completed, the induced fault testing was performed with three-end lines loaded and in service. This paper describes and analyses the test procedure, consisting of CAPE simulations, end-to-end test with advanced secondary equipment and staged-fault test of a three-end power line in the Croatian transmission system.

Keywords

  • Distance protection
  • three-end line
  • Croatian power system
  • protection
  • fault
  • simulation
  • teleprotection scheme
  • communication

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