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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 1 (February 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

Pattern classification of Myo-Electrical signal during different Maximum Voluntary Contractions: A study using BSS techniques

Published Online: 15 Feb 2010
Page range: 1 - 6

Abstract

Pattern classification of Myo-Electrical signal during different Maximum Voluntary Contractions: A study using BSS techniques

The presence of noise and cross-talk from closely located and simultaneously active muscles is exaggerated when the level of muscle contraction is very low. Due to this the current applications of surface electromyogram (sEMG) are infeasible and unreliable in pattern classification. This research reports a new technique of sEMG using Independent Component Analysis (ICA). The technique uses blind source separation (BSS) methods to classify the patterns of Myo-electrical signals during different Maximum Voluntary Contraction (MVCs) at different low level finger movements. The results of the experiments indicate that patterns using ICA of sEMG is a reliable (p<0.001) measure of strength of muscle contraction even when muscle activity is only 20% MVC. The authors propose that ICA is a useful indicator of muscle properties and is a useful indicator of the level of muscle activity.

Keywords

  • Surface Electromyography
  • Independent component Analysis
  • Blind source separation
  • Gestures
  • Maximum Voluntary Contractions
  • RMS
  • Motor Unit Action Potential
access type Open Access

Application of Microwave Moisture Sensor for Determination of Oil Palm Fruit Ripeness

Published Online: 15 Feb 2010
Page range: 7 - 14

Abstract

Application of Microwave Moisture Sensor for Determination of Oil Palm Fruit Ripeness

This paper describes the development of a low cost coaxial moisture sensor for the determination of moisture content (30 % to 80 % wet-weight basis) of the oil palm fruits of various degree of fruit ripeness. The sensor operating between 1 GHz and 5 GHz was fabricated from an inexpensive 4.1 mm outer diameter SMA coaxial stub contact panel which is suitable for single fruit measurement. The measurement system consists of the sensor and a PC-controlled vector network analyzer (VNA). The actual moisture content was determined by standard oven drying method and compared with predicted value of fruit moisture content obtained using the studied sensor. The sensor was used to monitor fruit ripeness based on the measurement of the phase or magnitude of reflection coefficient and the dielectric measurement software was developed to control and acquire data from the VNA using Agilent VEE. This software was used to calculate the complex relative permittivity from the measured reflection coefficient between 1GHz and 5 GHz.

Keywords

  • Vector network analyzer
  • moisture content
  • reflection coefficient
  • oil palm fruits
  • microwave sensors
  • dielectric constant
access type Open Access

Microcontroller Based Capacitive Mass Measuring System

Published Online: 15 Feb 2010
Page range: 15 - 18

Abstract

Microcontroller Based Capacitive Mass Measuring System

The paper deals with a new design of a capacitive sensor developed for the accurate and precise measurement of mass. It employs a co-axial cylinder based capacitive sensor whose capacitance decreases linearly with mass, due to the shielding effect of the conducting shield, which moves between the stationary cylinders of the capacitor with the movement of the mass holder. An accurate capacitance to voltage converting system is used to detect the mass in terms of voltage. Linear relationship between mass and output signal is obtained with the help of microcontroller. The presented sensor has high order of linearity, flexibility in design and controllable damping. The overall size of the sensor may be reduced to very small values by this design. It is highly robust and may be attached to any complex system. For the spring, used in the system, mass sensor can measure up to 7 kg.

Keywords

  • Capacitive sensor
  • Mass sensor
  • Capacitance measuring system
  • Microcontroller
  • spring
access type Open Access

Three Steps towards Metrological Traceability for Ballistics Signature Measurements

Published Online: 15 Feb 2010
Page range: 19 - 21

Abstract

Three Steps towards Metrological Traceability for Ballistics Signature Measurements

The National Institute of Standards and Technology (NIST) in collaboration with the Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF) has developed the Standard Reference Material (SRM) bullets and casings. NIST and ATF are proposing to establish a National Ballistics Measurement Traceability and Quality System for ballistics signature measurements and correlations using these materials. In this paper, three key steps towards metrological traceability for ballistics signature measurements are discussed that include: 1) Establishing a reference standard; 2) Establishing an unbroken chain of calibrations; and 3) Evaluating measurement uncertainty.

Keywords

  • Traceability
  • forensic science
  • ballistics signature
  • standard reference material
  • standard bullet
  • standard casing
access type Open Access

Optimization of Measuring Current for Chopper Low Resistance Comparator

Published Online: 15 Feb 2010
Page range: 22 - 24

Abstract

Optimization of Measuring Current for Chopper Low Resistance Comparator

The article describes systematic error analysis for realized chopper low-resistance comparator. The objective was to determine optimal working conditions, considering limited resolution (about 10 nV) and resistance variation due to self-heating caused by increase of measuring current. The analysis and performances of realized chopper low-resistance comparator prototype instrument confirmed the initial assumptions of applied principles. The error for 1 A measuring current is 1.15 ppm in the measuring range of 10 mΩ. It is possible to use the same principle for calculation of optimal measuring current and measurement error in other measurement ranges, as well.

Keywords

  • Low-resistance measurement
  • chopper comparator
  • error analysis
access type Open Access

The New Bridge Converter Control Method

Published Online: 15 Feb 2010
Page range: 25 - 27

Abstract

The New Bridge Converter Control Method

The article describes a new control method of transistor power bridge converter. It is a new one, because of some original solutions and its difference in comparison to existing methods. It's irrelevant of load, similar to the "phase shifted" control method. It is easy to realize using ordinary electronic elements. A significant advantage of method is the possibility of permanent output current monitoring by measuring the voltage sag on a pair of transistors. That allows a very efficient current protection.

Keywords

  • Control method
  • Bridge converter
  • PWM
6 Articles
access type Open Access

Pattern classification of Myo-Electrical signal during different Maximum Voluntary Contractions: A study using BSS techniques

Published Online: 15 Feb 2010
Page range: 1 - 6

Abstract

Pattern classification of Myo-Electrical signal during different Maximum Voluntary Contractions: A study using BSS techniques

The presence of noise and cross-talk from closely located and simultaneously active muscles is exaggerated when the level of muscle contraction is very low. Due to this the current applications of surface electromyogram (sEMG) are infeasible and unreliable in pattern classification. This research reports a new technique of sEMG using Independent Component Analysis (ICA). The technique uses blind source separation (BSS) methods to classify the patterns of Myo-electrical signals during different Maximum Voluntary Contraction (MVCs) at different low level finger movements. The results of the experiments indicate that patterns using ICA of sEMG is a reliable (p<0.001) measure of strength of muscle contraction even when muscle activity is only 20% MVC. The authors propose that ICA is a useful indicator of muscle properties and is a useful indicator of the level of muscle activity.

Keywords

  • Surface Electromyography
  • Independent component Analysis
  • Blind source separation
  • Gestures
  • Maximum Voluntary Contractions
  • RMS
  • Motor Unit Action Potential
access type Open Access

Application of Microwave Moisture Sensor for Determination of Oil Palm Fruit Ripeness

Published Online: 15 Feb 2010
Page range: 7 - 14

Abstract

Application of Microwave Moisture Sensor for Determination of Oil Palm Fruit Ripeness

This paper describes the development of a low cost coaxial moisture sensor for the determination of moisture content (30 % to 80 % wet-weight basis) of the oil palm fruits of various degree of fruit ripeness. The sensor operating between 1 GHz and 5 GHz was fabricated from an inexpensive 4.1 mm outer diameter SMA coaxial stub contact panel which is suitable for single fruit measurement. The measurement system consists of the sensor and a PC-controlled vector network analyzer (VNA). The actual moisture content was determined by standard oven drying method and compared with predicted value of fruit moisture content obtained using the studied sensor. The sensor was used to monitor fruit ripeness based on the measurement of the phase or magnitude of reflection coefficient and the dielectric measurement software was developed to control and acquire data from the VNA using Agilent VEE. This software was used to calculate the complex relative permittivity from the measured reflection coefficient between 1GHz and 5 GHz.

Keywords

  • Vector network analyzer
  • moisture content
  • reflection coefficient
  • oil palm fruits
  • microwave sensors
  • dielectric constant
access type Open Access

Microcontroller Based Capacitive Mass Measuring System

Published Online: 15 Feb 2010
Page range: 15 - 18

Abstract

Microcontroller Based Capacitive Mass Measuring System

The paper deals with a new design of a capacitive sensor developed for the accurate and precise measurement of mass. It employs a co-axial cylinder based capacitive sensor whose capacitance decreases linearly with mass, due to the shielding effect of the conducting shield, which moves between the stationary cylinders of the capacitor with the movement of the mass holder. An accurate capacitance to voltage converting system is used to detect the mass in terms of voltage. Linear relationship between mass and output signal is obtained with the help of microcontroller. The presented sensor has high order of linearity, flexibility in design and controllable damping. The overall size of the sensor may be reduced to very small values by this design. It is highly robust and may be attached to any complex system. For the spring, used in the system, mass sensor can measure up to 7 kg.

Keywords

  • Capacitive sensor
  • Mass sensor
  • Capacitance measuring system
  • Microcontroller
  • spring
access type Open Access

Three Steps towards Metrological Traceability for Ballistics Signature Measurements

Published Online: 15 Feb 2010
Page range: 19 - 21

Abstract

Three Steps towards Metrological Traceability for Ballistics Signature Measurements

The National Institute of Standards and Technology (NIST) in collaboration with the Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF) has developed the Standard Reference Material (SRM) bullets and casings. NIST and ATF are proposing to establish a National Ballistics Measurement Traceability and Quality System for ballistics signature measurements and correlations using these materials. In this paper, three key steps towards metrological traceability for ballistics signature measurements are discussed that include: 1) Establishing a reference standard; 2) Establishing an unbroken chain of calibrations; and 3) Evaluating measurement uncertainty.

Keywords

  • Traceability
  • forensic science
  • ballistics signature
  • standard reference material
  • standard bullet
  • standard casing
access type Open Access

Optimization of Measuring Current for Chopper Low Resistance Comparator

Published Online: 15 Feb 2010
Page range: 22 - 24

Abstract

Optimization of Measuring Current for Chopper Low Resistance Comparator

The article describes systematic error analysis for realized chopper low-resistance comparator. The objective was to determine optimal working conditions, considering limited resolution (about 10 nV) and resistance variation due to self-heating caused by increase of measuring current. The analysis and performances of realized chopper low-resistance comparator prototype instrument confirmed the initial assumptions of applied principles. The error for 1 A measuring current is 1.15 ppm in the measuring range of 10 mΩ. It is possible to use the same principle for calculation of optimal measuring current and measurement error in other measurement ranges, as well.

Keywords

  • Low-resistance measurement
  • chopper comparator
  • error analysis
access type Open Access

The New Bridge Converter Control Method

Published Online: 15 Feb 2010
Page range: 25 - 27

Abstract

The New Bridge Converter Control Method

The article describes a new control method of transistor power bridge converter. It is a new one, because of some original solutions and its difference in comparison to existing methods. It's irrelevant of load, similar to the "phase shifted" control method. It is easy to realize using ordinary electronic elements. A significant advantage of method is the possibility of permanent output current monitoring by measuring the voltage sag on a pair of transistors. That allows a very efficient current protection.

Keywords

  • Control method
  • Bridge converter
  • PWM

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