فهرست مطالب

Electrical Systems and Signals - Volume:3 Issue:1, 2016
  • Volume:3 Issue:1, 2016
  • تاریخ انتشار: 1395/03/28
  • تعداد عناوین: 6
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  • Hamid Reza Mosaddegh, Hossein Abootorabi Zarchi * Page 1
    In this paper, a variable structure controller is proposed to control the torque of brushless doubly fed induction generator with considering maximum torque per Ampere (MTPA) strategy. Based on this control approach, a sliding mode controller with a PI is designed in order to reduce the torque pulsations during steady-state behavior while the fast response and robustness merits of the classic DTC are preserved. Also this method decreases the copper losses with minimizing the magnitude of power and control windings currents without deteriorating the dynamic performance. The presented method, guarantees maximum power point tracking (MPPT) with a desirable operation. The simulation results verify an accurate, quick and robust operation of the brushless doubly fed induction generator for wind turbine applications.
    Keywords: Brushless doubly fed induction generator (BDFIG), Maximum Torque Per Ampere (MTPA), Sliding mode control (SMC), Torque control, Wind turbine
  • Saeid Marjani, Seyed Ebrahim Hosseini * Page 9
    In this paper, the radio-frequency (RF) performances and small-signal parameters of double-gate (DG) square-shaped extended source tunneling field-effect transistors (TFETs) are investigated and compared with those of single-gate (SG) square-shaped extended source TFETs in terms of their cut-off and maximum oscillation frequencies and small-signal parameters. By using of a nonquasi-static (NQS) radio-frequency model, the smallsignal parameters have been extracted. The results show that the DG square-shaped extended source TFET has higher transconductance, cut-off and maximum oscillation frequencies than single gate structure. The modeled Yparameters are in close agreement with the extracted parameters for high frequency range up to the cut-off frequency. Results suggest that the DG square-shaped extended source TFETs seem to be the most optimal ones to replace MOSFET for ultralow power applications and RF devices.
    Keywords: Double-gate (DG), radio-frequency (RF), nonquasistatic (NQS), extended source, tunneling fieldeffecttransistor (TFET)
  • Mojtaba Joodaki *, Amir Attar Page 15
    As clock frequency and switching current of DRAM (dynamic random access memory) modules are ever increasing, electromagnetic interference (EMI) of such modules is gaining a very high degree of importance. Normally EMI measurements of memory modules are performed implementing complete motherboards or PCs. This makes it very difficult to only separate the radiated EMI of the memory module with a single EMI measurement. This is the first attempt to construct a shielded measurement setup for radiated EMI for DRAM PCBs. The measurement setup is fabricated and tested for un-buffered double data rate (DDR) modules and gives excellent results. This is very helpful in EMI and electromagnetic compatibility (EMC) investigation of memory modules. Although the measurement setup is just implemented for memory modules, the approach can be used for other types of PCBs too.
    Keywords: EMC, EMI measurement, DRAM PCBs radiation
  • Hamidreza Arasteh, Mohammad Sadegh Sepasian, Vahid Vahidinasab* Page 23
    The planning of an active distribution system is investigated in this study. This paper conducts a novel concept of smart distribution system reconfiguration and planning problem. Proposed problem uses the concept of distribution system reconfiguration (DSR) with the aim of reducing and postponing the expansion requirements, while the potential of demand response (DR) programs are considered. DR programs are modeled as virtual and distributed resources to be dealt with the distribution system expansion planning (DEP) problem in the long term time horizon. Indeed, the main purpose of this paper is to propose “demand response and distribution system reconfiguration and expansion planning (DR-DSREP)” problem to identify the impact of DSR and DR on the expansion planning of distribution systems. The 33-bus distribution system is utilized in numerical studies to investigate the performance and effectiveness of the proposed problem. The simulation results show the efficiency and advantage of the proposed methodology.
    Keywords: Active distribution system, demand response, distribution expansion planning, distribution reconfiguration
  • Saman Shoorabi Sani *, Majid Baghaei Nejad, Mona Kalate Arabi Page 37
    In this study, a system for monitoring the structural health of bridge deck and predicting various possible damages to this section was designed based on measuring the temperature and humidity with the use of wireless sensor networks then it was implemented and investigated. This paper also presents the experimental development of an automatic wireless sensor monitoring system for concrete structures. The objective is to provide a solution to measure both temperature and humidity inside a concrete structure. The research has been focused in the early age and curing phase period. Four solutions have been addressed. The first one involves the use of a negative temperature coefficient thermistor and an IRIS mote allowing for the creation of an IEEE 802.15.4 network. The second one considers the use of the SHT15 sensor, together with the PIC18F4680 microcontroller or the Arduino platform. The third solution involves the use of the SHT21S sensor and the eZ430-RF2500 wireless development tool platform for the MSP430 microcontroller. Finally, the fourth solution considers both the SHT15 and SHT21S sensors completely shielded allowing for the creation of a long-term solution. The potential of applying the proposed inexpensive wireless sensor network approach is completely investigated and verified.
    Keywords: Structural health monitoring, wireless sensor networks, concrete, sensor, temperature, humidity
  • Amir Hossein Poorjam, Mohamad Hasan Bahari, Hugo Van Hamme Page 47
    This paper proposes a novel approach for automatic speaker weight estimation from spontaneous telephone speech signals. In this method, each utterance is modeled using the i-vector framework which is based on the factor analysis on Gaussian Mixture Model (GMM) mean super vectors, and the Non-negative Factor Analysis (NFA) framework which is based on a constrained factor analysis on GMM weight super vectors. Then, the available information in both Gaussian means and Gaussian weights is exploited through a feature-level fusion of the i-vectors and the NFA vectors. Finally, a least-squares support vector regression (LSSVR) is employed to estimate the weight of speakers from the given utterances. The proposed approach is evaluated on spontaneous telephone speech signals of National Institute of Standards and Technology (NIST) 2008 and 2010 Speaker Recognition Evaluation (SRE) corpora. To investigate theeffectiveness of the proposed approach, this method is compared to the i-vector-based speaker weight estimation and an alternative fusion scheme, namely the score-level fusion. Experimental results over 2339 utterances show that the correlation coefficients between the actual and the estimated weights of female and male speakers are 0.49 and 0.56, respectively, which indicate the effectiveness of the proposed method in speaker weight estimation.
    Keywords: I, vector, non, negative factor analysis, leastsquares support vector regression, speaker weight estimation