فهرست مطالب

Iranian Journal of Electrical and Electronic Engineering
Volume:5 Issue: 1, Mar 2009

  • تاریخ انتشار: 1387/12/11
  • تعداد عناوین: 7
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  • M. H. Sedaaghi Page 1
    Accurate gender classification is useful in speech and speaker recognition as well as speech emotion classification, because a better performance has been reported when separate acoustic models are employed for males and females. Gender classification is also apparent in face recognition, video summarization, human-robot interaction, etc. Although gender classification is rather mature in applications dealing with images, it is still in its infancy in speech processing. Age classification, on the other hand, is also concerned as a useful tool in different applications, like issuing different permission levels for different aging groups. This paper concentrates on a comparative study of gender and age classification algorithms applied to speech signal. Experimental results are reported for the Danish Emotional Speech database (DES) and English Language Speech Database for Speaker Recognition (ELSDSR). The Bayes classifier using sequential floating forward selection (SFFS) for feature selection, probabilistic Neural Networks (PNNs), support vector machines (SVMs), the K nearest neighbor (K-NN) and Gaussian mixture model (GMM), as different classifiers, are empirically compared in order to determine the best classifier for gender and age classification when speech signal is processed. It is proven that gender classification can be performed with an accuracy of 95% approximately using speech signal either from both genders or male and female separately. The accuracy for age classification is about 88%.
  • V. Vakil, H. Aghaeinia Page 13
    The throughput enhancement of Space-Time Spreading (STS)-based Multicarrier Direct Sequence Code Division Multiple Access (MC DS-CDMA) system is investigated in this paper. Variable Spreading Factor (VSF) is utilized to improve the data throughput of the system. In this contribution, an analytical approach is proposed to compute a new expression for the Bit Error Rate (BER) performance of the STS-based MC DS-CDMA system against pre-dispreading Signal-to-Noise Ratio (SNR) for different values of spreading factor (SF). The other contribution of the paper is deriving a new closed form expression for computing the throughput enhancement and the BER performance of the VSF STS-based MC DS-CDMA system over Rayleigh fading channel. It is demonstrated that using VSF method in STS-based MC DS-CDMA system improves the throughput of the system by keeping the BER performance at the target level.
  • H. Ghanei Yakhdan, M. Khademi, J. Chitizadeh Page 23
    The performance of video transmission over wireless channels is limited by the channel noise. Thus many error resilience tools have been incorporated into the MPEG-4 video compression method. In addition to these tools, the unequal error protection (UEP) technique has been proposed to protect the different parts in an MPEG-4 video packet with different channel coding rates based on the rate compatible punctured convolutional (RCPC) codes. However, it is still not powerful enough for the noisy channels. To provide more robust MPEG-4 video transmission, this paper proposes a modified unequal error protection technique based on the mutual information of two video frames. In the proposed technique, the dynamic channel coder rates are determined online based on the mutual information of two consecutive video frames. With this technique, irregular and high motion areas that are more sensitive to errors can get more protection. Simulation results show that the proposed technique enhances both subjective visual quality and average peak signal to noise ratio (PSNR) about 2.5 dB, comparing to the traditional UEP method.
  • P. M. Farahabadi, H. Miar, Naimi, A. Ebrahimzadeh Page 32
  • E. Farshidi Page 42
    In this paper a new synthesis for circuit design of Euclidean distance calculation is presented. The circuit is implemented based on a simple two-quadrant squarer/divider block. The circuit that employs floating gate MOS (FG-MOS) transistors operating in weak inversion region, features low circuit complexity, low power (<20uW), low supply voltage (0.5V), two quadrant input current, wide dynamic range and immunity from body effect. In addition, this circuit is designed in modular methodology, leading to a very regular structure. The circuit was successfully applied to the recognition of some simple patterns. Simulation results of the circuit by HSPICE show high performance in the separation and confirm the validity of the proposed technique.
  • A. Dastfan, F. Behrangi Page 51
    A conventional high power DC power supply systems consist of a three-phase diode rectifier followed by a high frequency converter to supply loads at regulated DC voltage. These rectifiers draw significant harmonic currents from the utility, resulting in poor input power factor. In this paper, a DC power supply based on dual-bridge matrix converter (DBMC) with reduced number of switches is proposed. In the proposed circuit, three switches convert the low frequency AC input to a DC link. A single-phase bridge inverter converts the DC-link to a high frequency AC output. The output of the matrix converter is then processed via a high frequency isolation transformer and rectified to the regulated DC voltage. In the proposed topology only a simple voltage control loop ensures that the output voltage is regulated against load changes as well as input supply variations and the current control loop is not used to correct the input currents. Theory analysis and simulation are made to investigate performance of the proposed circuit. Simulation results show that in the proposed power supply with 7-switch, the input currents are of a high quality under varying load conditions and input voltage.
  • K. Malekian, J. Milimonfared, B. Majidi Page 60
    The main theme of this paper is to present novel controller, which is a genetic based fuzzy Logic controller, for interior permanent magnet synchronous motor drives with direct torque control. A radial basis function network has been used for online tuning of the genetic based fuzzy logic controller. Initially different operating conditions are obtained based on motor dynamics incorporating uncertainties. At each operating condition, a genetic algorithm is used to optimize fuzzy logic parameters in closed-loop direct torque control scheme. In other words, the genetic algorithm finds optimum input and output scaling factors and optimum number of membership functions. This optimization procedure is utilized to obtain the minimum speed deviation, minimum settling time, zero steady-state error. The control scheme has been verified by simulation tests with a prototype interior permanent magnet synchronous motor.