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Volumen 5 (2014): Heft 1 (May 2014)

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Volumen 3 (2013): Heft 1 (August 2013)

Volumen 2 (2013): Heft 1 (April 2013)

Volumen 1 (2012): Heft 1 (December 2012)

Zeitschriftendaten
Format
Zeitschrift
eISSN
2255-9159
Erstveröffentlichung
31 Jan 2013
Erscheinungsweise
2 Hefte pro Jahr
Sprachen
Englisch

Suche

Volumen 5 (2014): Heft 1 (May 2014)

Zeitschriftendaten
Format
Zeitschrift
eISSN
2255-9159
Erstveröffentlichung
31 Jan 2013
Erscheinungsweise
2 Hefte pro Jahr
Sprachen
Englisch

Suche

10 Artikel
Open Access

Application of Simplified Neutral Point Clamped Multilevel Converter in a Small Wind Turbine

Online veröffentlicht: 17 May 2014
Seitenbereich: 5 - 10

Zusammenfassung

Abstract

In low power distributed generation systems low cost together with the energy quality requirements are a key element. It is known that quality of voltage waveforms generated from multilevel converters is better in comparison with those from two-level. Due to advancements in power electronics and microcontrollers, multilevel converters are being built with the use of integrated power modules thus this type of converters are getting more compact in size. This paper investigates performance of a derivation from the most popular multilevel topology - a neutral point clamped converter (NPC). Applying the idea for simplifying the topology by reducing the number of switches (what came from drives) this NPC converter is capable of bidirectional AC/DC/AC operation. For the AC/DC part two schemes are tested: Direct Torque Control Space Vector Modulated and Field Oriented Control but for the DC/AC part a control scheme utilizing the proportional-resonant controller was chosen. Laboratory setup was based on a permanent magnet synchronous generator with control and acquisition completed with the help of dSpace 1005 control box. Experimental verification shows that system operates properly.

Schlüsselwörter

  • AC-DC power converters
  • Power conversion harmonics
  • Wind energy generation
  • Bidirectional power flow
Open Access

Design of AC-DC Grid Connected Converter using Multi-Objective Optimization

Online veröffentlicht: 17 May 2014
Seitenbereich: 11 - 19

Zusammenfassung

Abstract

Power electronic circuits, in particular AC-DC converters are complex systems, many different parameters and objectives have to be taken into account during the design process. Implementation of Multi-Objective Optimization (MOO) seems to be attractive idea, which used as designer supporting tool gives possibility for better analysis of the designed system. This paper presents a short introduction to the MOO applied in the field of power electronics. Short introduction to the subject is given in section I. Then, optimization process and its elements are briefly described in section II. Design procedure with proposed optimization parameters and performance indices for AC-DC Grid Connected Converter (GCC) interfacing distributed systems is introduced in section III. Some preliminary optimization results, achieved on the basis of analytical and simulation study, are shown at each stage of designing process. Described optimization parameters and performance indices are part of developed global optimization method dedicated for ACDC GCC introduced in section IV. Described optimization method is under development and only short introduction and basic assumptions are presented. In section V laboratory prototype of high efficient and compact 14 kVA AC-DC converter is introduced. The converter is elaborated based on performed designing and optimization procedure with the use of silicon carbide (SiC) power semiconductors. Finally, the paper is summarized and concluded in section VI. In presented work theoretical research are conducted in parallel with laboratory prototyping e.g. all theoretical ideas are verified in laboratory using modern DSP microcontrollers and prototypes of the ACDC GCC.

Schlüsselwörter

  • AC-DC power converters
  • Silicon carbide
  • Design optimization
  • Pareto optimization
Open Access

Sliding-Mode Observer for Speed and Position Sensorless Control of Linear-PMSM

Online veröffentlicht: 17 May 2014
Seitenbereich: 20 - 26

Zusammenfassung

Abstract

The paper presents a sliding-mode observer that utilizes sigmoid function for speed and position sensorless control of permanent-magnet linear synchronous motor (PMLSM). In conventional sliding mode observer method there are the chattering phenomenon and the phase lag. Thus, in order to avoid the usage of the low pass filter and the phase compensator based on back EMF, in this paper a sliding mode observer with sigmoid function for detecting the back EMF in a PMLSM is designed to estimate the speed and the position of the rotor. Most of conventional sliding mode observers use sign or saturation functions which need low pass filter in order to detect back electromotive force (back EMF). In this paper a sigmoid function is used instead of discontinuous sign function to decrease undesirable chattering phenomenon. By reducing the chattering, detecting of the back EMF can be made directly from switching signal without any low pass filter. Thus the delay time in the proposed observer is eliminated because of the low pass filter. Furthermore, there is no need to compensate phase fault in position and speed estimating of linear-PMSM. Advantages of the proposed observer have been shown by simulation with MATLAB software.

Schlüsselwörter

  • Permanent magnet motors
  • Motor drives
  • Observers
  • Sliding mode control
  • Sensorless control
Open Access

Library of Samples for E-Vehicle Propulsion Drive Tuning

Online veröffentlicht: 17 May 2014
Seitenbereich: 27 - 33

Zusammenfassung

Abstract

The majority of testing cycles for the vehicle comparison is the long-term cycles and could not be used for the short-term transient mode imitations. Also, all the used nowadays testing cycles were designed for internal combustion engine vehicles and take into account not only energy and mechanical aspects, but also pollution and internal combustion engine characteristics. The paper presents a collection of sample signals developed to explore and simulate multiple system impacts to emulate different reference and load conditions. The study describes the major driving modes, such as the constant-speed cruising, speeding up and braking, typical parking regimes, uphill and downhill motion, and taking a turn. The developed testing equipment and software are described. Responses of the battery vehicle drives to the changeable controls and disturbances were studied in the laboratory test bench. The set of test cycles prepared in the frame of the ABB control arrangement was applied to the system evaluation and assessment. The developed methodology can be recommended to adjust the electric drives for different kinds of testing equipment. Experimental validation of the described approach has demonstrated the broad possibilities for the steady-state and transient modes of vehicle quality evaluation. It suits for recommendations that can be made with regard to the tuning of the drive regulators, control looping, sensor allocation, and feedback arrangements.

Schlüsselwörter

  • Automotive applications
  • Electric vehicles
  • Test equipment
  • Variable speed drives
Open Access

Metamodels for Optimum Design of Outer-Rotor Synchronous Reluctance Motor

Online veröffentlicht: 17 May 2014
Seitenbereich: 34 - 39

Zusammenfassung

Abstract

A new design of synchronous reluctance motor with segment-shaped outer rotor is presented and investigated in this paper. In order to obtain correct recommendations for optimal design of the studied synchronous reluctance motor, analytical relations of motor electromagnetic parameters and geometrical dimensions (also known as metamodels) have been synthesized. Electromagnetic parameters, which have been used for metamodels synthesis, are obtained by means of magnetostatic field numerical calculations with finite element method using software QuickField.

The paper includes the analysis of the studied synchronous reluctance motor geometrical parameters (stator outer diameter, height and overlap angle of rotor’s segment-shaped packages) influence on the electromagnetic torque per unit volume. Testing of synthesized metamodels shows that relative difference between the results obtained by numerical calculations and those obtained with the help of synthesized metamodels does not exceed eight percent at experimental points and intermediate points as well. The proposed optimal design of the segment-shaped outerrotor synchronous reluctance motor obtained with the help of synthesized metamodels has been compared with a salient-pole outer-rotor synchronous reluctance motor having ferromagnetic yoke with the same value of the electromagnetic torque. The comparison results of both motors show that the highest value of electromagnetic torque per unit volume can be achieved with the proposed new design of the synchronous reluctance motor with segment-shaped outer rotor.

Schlüsselwörter

  • AC motors
  • Design optimization
  • Magnetostatics
  • Metamodeling
  • Finite element analysis
Open Access

Design Aspects and Test of an Inductive Fault Current Limiter

Online veröffentlicht: 17 May 2014
Seitenbereich: 40 - 45

Zusammenfassung

Abstract

Magnetic shielding inductive fault current limiters with high temperature superconducting tapes are considered as emerging devices that provide technology for the advent of modern power grids. The development of such limiters requires magnetic iron cores and leads to several design challenges regarding the constitutive parts of the limiter, namely the primary and secondary windings. Preliminary tests in a laboratory scale prototype have been carried out considering an assembly designed for simplicity in which the optimization of the magnetic coupling between the primary and secondary was not the main focus. This work addresses the design configuration of an inductive current limiter prototype regarding the assembly of the primary and secondary windings in the core. The prototype is based on a closed magnetic core wound by a primary, built from a normal electric conductor, and a short-circuited secondary, built from first generation superconducting tape. Four different design configurations are considered. Through experimental tests, the performance of such prototype is discussed and compared, in terms of normal and fault operation regimes. The results show that all the configurations assure effective magnetic shielding at normal operation regime, however, at fault operation regime, there are differences among configurations.

Schlüsselwörter

  • Fault current limiters
  • High-temperature superconductors
  • Power grids
  • Short-circuit currents
Open Access

The Mathematical Modelling of Heat Transfer in Electrical Cables

Online veröffentlicht: 17 May 2014
Seitenbereich: 46 - 53

Zusammenfassung

Abstract

This paper describes a mathematical modelling approach for heat transfer calculations in underground high voltage and middle voltage electrical power cables. First of the all typical layout of the cable in the sand or soil is described. Then numerical algorithms are targeted to the two-dimensional mathematical models of transient heat transfer. Finite Volume Method is suggested for calculations. Different strategies of nonorthogonality error elimination are considered. Acute triangles meshes were applied in two-dimensional domain to eliminate this error. Adaptive mesh is also tried. For calculations OpenFOAM open source software which uses Finite Volume Method is applied. To generate acute triangles meshes aCute library is used. The efficiency of the proposed approach is analyzed. The results show that the second order of convergence or close to that is achieved (in terms of sizes of finite volumes). Also it is shown that standard strategy, used by OpenFOAM is less efficient than the proposed approach. Finally it is concluded that for solving real problem a spatial adaptive mesh is essential and adaptive time steps also may be needed.

Schlüsselwörter

  • Power transmission
  • Numerical models
  • Finite element analysis
  • Finite volume methods
  • Convergence of numerical methods
Open Access

An Efficiency Analysis of Augmented Reality Marker Recognition Algorithm

Online veröffentlicht: 17 May 2014
Seitenbereich: 54 - 60

Zusammenfassung

Abstract

The article reports on the investigation of augmented reality system which is designed for identification and augmentation of 100 different square markers. Marker recognition efficiency was investigated by rotating markers along x and y axis directions in range from −90° to 90°. Virtual simulations of four environments were developed: a) an intense source of light, b) an intense source of light falling from the left side, c) the non-intensive light source falling from the left side, d) equally falling shadows. The graphics were created using the OpenGL graphics computer hardware interface; image processing was programmed in C++ language using OpenCV, while augmented reality was developed in Java programming language using NyARToolKit. The obtained results demonstrate that augmented reality marker recognition algorithm is accurate and reliable in the case of changing lighting conditions and rotational angles - only 4 % markers were unidentified. Assessment of marker recognition efficiency let to propose marker classification strategy in order to use it for grouping various markers into distinct markers’ groups possessing similar recognition properties.

Schlüsselwörter

  • Computers and information processing
  • Computational efficiency
  • Augmented reality
  • Image recognition
  • Open source software
Open Access

Improving Speech Recognition Rate through Analysis Parameters

Online veröffentlicht: 17 May 2014
Seitenbereich: 61 - 66

Zusammenfassung

Abstract

Speech signal is redundant and non-stationary by nature. Because of vocal tract inertness these variations are not very rapid and the signal can be considered as stationary in short segments. It is presumed that in short-time magnitude spectrum the most distinct information of speech is contained. This is the main reason for speech signal analysis in frame-by-frame manner. The analyzed speech signal is segmented into overlapping segments (so-called frames) for this purpose. Segments of 15-25 ms with the overlap of 10-15 ms are used usually.

In this paper we present results of our investigation of analysis window length and frame shift influence on speech recognition rate. We have analyzed three different cepstral analysis approaches for this purpose: mel frequency cepstral analysis (MFCC), linear prediction cepstral analysis (LPCC) and perceptual linear prediction cepstral analysis (PLPC). The highest speech recognition rate was obtained using 10 ms length analysis window with the frame shift varying from 7.5 to 10 ms (regardless of analysis type). The highest increase of recognition rate was 2.5 %.

Schlüsselwörter

  • Computers and information processing
  • Speech analysis
  • Speech recognition
  • Speech enhancement
Open Access

Call Duration Characteristics based on Customers Location

Online veröffentlicht: 17 May 2014
Seitenbereich: 67 - 73

Zusammenfassung

Abstract

Nowadays a lot of different researches are performed based on call duration distributions (CDD) analysis. However, the majority of studies are linked with social relationships between the people. Therefore the scarcity of information, how the call duration is associated with a user's location, is appreciable. The goal of this paper is to reveal the ties between user's voice call duration and the location of call. For this reason we analyzed more than 5 million calls from real mobile network, which were made over the base stations located in rural areas, roads, small towns, business and entertainment centers, residential districts. According to these site types CDD’s and characteristic features for call durations are given and discussed. Submitted analysis presents the users habits and behavior as a group (not an individual). The research showed that CDD’s of customers being them in different locations are not equal. It has been found that users at entertainment, business centers are tend to talk much shortly, than people being at home. Even more CDD can be distorted strongly, when machinery calls are evaluated. Hence to apply a common CDD for a whole network it is not recommended. The study also deals with specific parameters of call duration for distinguished user groups, the influence of network technology for call duration is considered.

Schlüsselwörter

  • Communications technology
  • Cellular networks
  • Communication system traffic
  • Telecommunication services
10 Artikel
Open Access

Application of Simplified Neutral Point Clamped Multilevel Converter in a Small Wind Turbine

Online veröffentlicht: 17 May 2014
Seitenbereich: 5 - 10

Zusammenfassung

Abstract

In low power distributed generation systems low cost together with the energy quality requirements are a key element. It is known that quality of voltage waveforms generated from multilevel converters is better in comparison with those from two-level. Due to advancements in power electronics and microcontrollers, multilevel converters are being built with the use of integrated power modules thus this type of converters are getting more compact in size. This paper investigates performance of a derivation from the most popular multilevel topology - a neutral point clamped converter (NPC). Applying the idea for simplifying the topology by reducing the number of switches (what came from drives) this NPC converter is capable of bidirectional AC/DC/AC operation. For the AC/DC part two schemes are tested: Direct Torque Control Space Vector Modulated and Field Oriented Control but for the DC/AC part a control scheme utilizing the proportional-resonant controller was chosen. Laboratory setup was based on a permanent magnet synchronous generator with control and acquisition completed with the help of dSpace 1005 control box. Experimental verification shows that system operates properly.

Schlüsselwörter

  • AC-DC power converters
  • Power conversion harmonics
  • Wind energy generation
  • Bidirectional power flow
Open Access

Design of AC-DC Grid Connected Converter using Multi-Objective Optimization

Online veröffentlicht: 17 May 2014
Seitenbereich: 11 - 19

Zusammenfassung

Abstract

Power electronic circuits, in particular AC-DC converters are complex systems, many different parameters and objectives have to be taken into account during the design process. Implementation of Multi-Objective Optimization (MOO) seems to be attractive idea, which used as designer supporting tool gives possibility for better analysis of the designed system. This paper presents a short introduction to the MOO applied in the field of power electronics. Short introduction to the subject is given in section I. Then, optimization process and its elements are briefly described in section II. Design procedure with proposed optimization parameters and performance indices for AC-DC Grid Connected Converter (GCC) interfacing distributed systems is introduced in section III. Some preliminary optimization results, achieved on the basis of analytical and simulation study, are shown at each stage of designing process. Described optimization parameters and performance indices are part of developed global optimization method dedicated for ACDC GCC introduced in section IV. Described optimization method is under development and only short introduction and basic assumptions are presented. In section V laboratory prototype of high efficient and compact 14 kVA AC-DC converter is introduced. The converter is elaborated based on performed designing and optimization procedure with the use of silicon carbide (SiC) power semiconductors. Finally, the paper is summarized and concluded in section VI. In presented work theoretical research are conducted in parallel with laboratory prototyping e.g. all theoretical ideas are verified in laboratory using modern DSP microcontrollers and prototypes of the ACDC GCC.

Schlüsselwörter

  • AC-DC power converters
  • Silicon carbide
  • Design optimization
  • Pareto optimization
Open Access

Sliding-Mode Observer for Speed and Position Sensorless Control of Linear-PMSM

Online veröffentlicht: 17 May 2014
Seitenbereich: 20 - 26

Zusammenfassung

Abstract

The paper presents a sliding-mode observer that utilizes sigmoid function for speed and position sensorless control of permanent-magnet linear synchronous motor (PMLSM). In conventional sliding mode observer method there are the chattering phenomenon and the phase lag. Thus, in order to avoid the usage of the low pass filter and the phase compensator based on back EMF, in this paper a sliding mode observer with sigmoid function for detecting the back EMF in a PMLSM is designed to estimate the speed and the position of the rotor. Most of conventional sliding mode observers use sign or saturation functions which need low pass filter in order to detect back electromotive force (back EMF). In this paper a sigmoid function is used instead of discontinuous sign function to decrease undesirable chattering phenomenon. By reducing the chattering, detecting of the back EMF can be made directly from switching signal without any low pass filter. Thus the delay time in the proposed observer is eliminated because of the low pass filter. Furthermore, there is no need to compensate phase fault in position and speed estimating of linear-PMSM. Advantages of the proposed observer have been shown by simulation with MATLAB software.

Schlüsselwörter

  • Permanent magnet motors
  • Motor drives
  • Observers
  • Sliding mode control
  • Sensorless control
Open Access

Library of Samples for E-Vehicle Propulsion Drive Tuning

Online veröffentlicht: 17 May 2014
Seitenbereich: 27 - 33

Zusammenfassung

Abstract

The majority of testing cycles for the vehicle comparison is the long-term cycles and could not be used for the short-term transient mode imitations. Also, all the used nowadays testing cycles were designed for internal combustion engine vehicles and take into account not only energy and mechanical aspects, but also pollution and internal combustion engine characteristics. The paper presents a collection of sample signals developed to explore and simulate multiple system impacts to emulate different reference and load conditions. The study describes the major driving modes, such as the constant-speed cruising, speeding up and braking, typical parking regimes, uphill and downhill motion, and taking a turn. The developed testing equipment and software are described. Responses of the battery vehicle drives to the changeable controls and disturbances were studied in the laboratory test bench. The set of test cycles prepared in the frame of the ABB control arrangement was applied to the system evaluation and assessment. The developed methodology can be recommended to adjust the electric drives for different kinds of testing equipment. Experimental validation of the described approach has demonstrated the broad possibilities for the steady-state and transient modes of vehicle quality evaluation. It suits for recommendations that can be made with regard to the tuning of the drive regulators, control looping, sensor allocation, and feedback arrangements.

Schlüsselwörter

  • Automotive applications
  • Electric vehicles
  • Test equipment
  • Variable speed drives
Open Access

Metamodels for Optimum Design of Outer-Rotor Synchronous Reluctance Motor

Online veröffentlicht: 17 May 2014
Seitenbereich: 34 - 39

Zusammenfassung

Abstract

A new design of synchronous reluctance motor with segment-shaped outer rotor is presented and investigated in this paper. In order to obtain correct recommendations for optimal design of the studied synchronous reluctance motor, analytical relations of motor electromagnetic parameters and geometrical dimensions (also known as metamodels) have been synthesized. Electromagnetic parameters, which have been used for metamodels synthesis, are obtained by means of magnetostatic field numerical calculations with finite element method using software QuickField.

The paper includes the analysis of the studied synchronous reluctance motor geometrical parameters (stator outer diameter, height and overlap angle of rotor’s segment-shaped packages) influence on the electromagnetic torque per unit volume. Testing of synthesized metamodels shows that relative difference between the results obtained by numerical calculations and those obtained with the help of synthesized metamodels does not exceed eight percent at experimental points and intermediate points as well. The proposed optimal design of the segment-shaped outerrotor synchronous reluctance motor obtained with the help of synthesized metamodels has been compared with a salient-pole outer-rotor synchronous reluctance motor having ferromagnetic yoke with the same value of the electromagnetic torque. The comparison results of both motors show that the highest value of electromagnetic torque per unit volume can be achieved with the proposed new design of the synchronous reluctance motor with segment-shaped outer rotor.

Schlüsselwörter

  • AC motors
  • Design optimization
  • Magnetostatics
  • Metamodeling
  • Finite element analysis
Open Access

Design Aspects and Test of an Inductive Fault Current Limiter

Online veröffentlicht: 17 May 2014
Seitenbereich: 40 - 45

Zusammenfassung

Abstract

Magnetic shielding inductive fault current limiters with high temperature superconducting tapes are considered as emerging devices that provide technology for the advent of modern power grids. The development of such limiters requires magnetic iron cores and leads to several design challenges regarding the constitutive parts of the limiter, namely the primary and secondary windings. Preliminary tests in a laboratory scale prototype have been carried out considering an assembly designed for simplicity in which the optimization of the magnetic coupling between the primary and secondary was not the main focus. This work addresses the design configuration of an inductive current limiter prototype regarding the assembly of the primary and secondary windings in the core. The prototype is based on a closed magnetic core wound by a primary, built from a normal electric conductor, and a short-circuited secondary, built from first generation superconducting tape. Four different design configurations are considered. Through experimental tests, the performance of such prototype is discussed and compared, in terms of normal and fault operation regimes. The results show that all the configurations assure effective magnetic shielding at normal operation regime, however, at fault operation regime, there are differences among configurations.

Schlüsselwörter

  • Fault current limiters
  • High-temperature superconductors
  • Power grids
  • Short-circuit currents
Open Access

The Mathematical Modelling of Heat Transfer in Electrical Cables

Online veröffentlicht: 17 May 2014
Seitenbereich: 46 - 53

Zusammenfassung

Abstract

This paper describes a mathematical modelling approach for heat transfer calculations in underground high voltage and middle voltage electrical power cables. First of the all typical layout of the cable in the sand or soil is described. Then numerical algorithms are targeted to the two-dimensional mathematical models of transient heat transfer. Finite Volume Method is suggested for calculations. Different strategies of nonorthogonality error elimination are considered. Acute triangles meshes were applied in two-dimensional domain to eliminate this error. Adaptive mesh is also tried. For calculations OpenFOAM open source software which uses Finite Volume Method is applied. To generate acute triangles meshes aCute library is used. The efficiency of the proposed approach is analyzed. The results show that the second order of convergence or close to that is achieved (in terms of sizes of finite volumes). Also it is shown that standard strategy, used by OpenFOAM is less efficient than the proposed approach. Finally it is concluded that for solving real problem a spatial adaptive mesh is essential and adaptive time steps also may be needed.

Schlüsselwörter

  • Power transmission
  • Numerical models
  • Finite element analysis
  • Finite volume methods
  • Convergence of numerical methods
Open Access

An Efficiency Analysis of Augmented Reality Marker Recognition Algorithm

Online veröffentlicht: 17 May 2014
Seitenbereich: 54 - 60

Zusammenfassung

Abstract

The article reports on the investigation of augmented reality system which is designed for identification and augmentation of 100 different square markers. Marker recognition efficiency was investigated by rotating markers along x and y axis directions in range from −90° to 90°. Virtual simulations of four environments were developed: a) an intense source of light, b) an intense source of light falling from the left side, c) the non-intensive light source falling from the left side, d) equally falling shadows. The graphics were created using the OpenGL graphics computer hardware interface; image processing was programmed in C++ language using OpenCV, while augmented reality was developed in Java programming language using NyARToolKit. The obtained results demonstrate that augmented reality marker recognition algorithm is accurate and reliable in the case of changing lighting conditions and rotational angles - only 4 % markers were unidentified. Assessment of marker recognition efficiency let to propose marker classification strategy in order to use it for grouping various markers into distinct markers’ groups possessing similar recognition properties.

Schlüsselwörter

  • Computers and information processing
  • Computational efficiency
  • Augmented reality
  • Image recognition
  • Open source software
Open Access

Improving Speech Recognition Rate through Analysis Parameters

Online veröffentlicht: 17 May 2014
Seitenbereich: 61 - 66

Zusammenfassung

Abstract

Speech signal is redundant and non-stationary by nature. Because of vocal tract inertness these variations are not very rapid and the signal can be considered as stationary in short segments. It is presumed that in short-time magnitude spectrum the most distinct information of speech is contained. This is the main reason for speech signal analysis in frame-by-frame manner. The analyzed speech signal is segmented into overlapping segments (so-called frames) for this purpose. Segments of 15-25 ms with the overlap of 10-15 ms are used usually.

In this paper we present results of our investigation of analysis window length and frame shift influence on speech recognition rate. We have analyzed three different cepstral analysis approaches for this purpose: mel frequency cepstral analysis (MFCC), linear prediction cepstral analysis (LPCC) and perceptual linear prediction cepstral analysis (PLPC). The highest speech recognition rate was obtained using 10 ms length analysis window with the frame shift varying from 7.5 to 10 ms (regardless of analysis type). The highest increase of recognition rate was 2.5 %.

Schlüsselwörter

  • Computers and information processing
  • Speech analysis
  • Speech recognition
  • Speech enhancement
Open Access

Call Duration Characteristics based on Customers Location

Online veröffentlicht: 17 May 2014
Seitenbereich: 67 - 73

Zusammenfassung

Abstract

Nowadays a lot of different researches are performed based on call duration distributions (CDD) analysis. However, the majority of studies are linked with social relationships between the people. Therefore the scarcity of information, how the call duration is associated with a user's location, is appreciable. The goal of this paper is to reveal the ties between user's voice call duration and the location of call. For this reason we analyzed more than 5 million calls from real mobile network, which were made over the base stations located in rural areas, roads, small towns, business and entertainment centers, residential districts. According to these site types CDD’s and characteristic features for call durations are given and discussed. Submitted analysis presents the users habits and behavior as a group (not an individual). The research showed that CDD’s of customers being them in different locations are not equal. It has been found that users at entertainment, business centers are tend to talk much shortly, than people being at home. Even more CDD can be distorted strongly, when machinery calls are evaluated. Hence to apply a common CDD for a whole network it is not recommended. The study also deals with specific parameters of call duration for distinguished user groups, the influence of network technology for call duration is considered.

Schlüsselwörter

  • Communications technology
  • Cellular networks
  • Communication system traffic
  • Telecommunication services

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