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Showing 2 results for Aghaei

V. Vakil, H. Aghaeinia,
Volume 5, Issue 1 (March 2009)

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.
S. H. Montazeri, A. Damaki Aliabad, F. Zare, S. Aghaei,
Volume 17, Issue 1 (March 2021)

The direct drive permanent magnet synchronous motor (DD-PMSM) is a suitable choice for high-precision position control applications. Among various control methods of this motor, the vector control approaches especially the field oriented control has a high-performance in the industrial drives. In this method, the components of stator current are controlled independently and as a result, the torque and flux are controlled continuously. Since there are some limitations and constraints in the motor, inverter, and control system, a new anti-windup gain scheduling PID controller based on the adaptive control principles is proposed for the position control loop. In the proposed method, different values are assigned to coefficients of the PID controller according to the position error to achieve high precision. Also, a very high-accuracy encoder and an ARM processor are used for measuring the instantaneous position and implementation of the proposed method, respectively. The simulation and experimental results validate the effectiveness, high accuracy, and good dynamic behavior of the proposed control method.

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