Showing 5 results for Ahmed
S. M. Ahmed, K. S. Ahmed, Y. M. Shuaib,
Volume 19, Issue 1 (March 2023)
Abstract
This article discusses the operating principle and simulation of closed loop control of a three phase induction motor (IM) powered by five level diode clamped multilevel inverter (DCMLI) using direct torque control (DTC) technique. The main purpose of this article is to regulate the torque and speed of an IM and to decrease total harmonic distortion (THD). In this article, a five-level inverter's direct modulation approach with the dc link voltage self-balancing is presented. To reduce capacitor voltage variation, the redundancies of various switch topologies for the creation of intermediate voltages are also used. The use of LC filter results in lower output voltage and current distortion. A multicarrier PWM control technique is used for DCMLI to provide high quality sinusoidal output voltage with decreased harmonics. This can be obtained by employing Sinusoidal Pulse Width Modulation (SPWM) method for speed and torque control. This demonstrates that the recommended method of controlling the motor's speed and torque is effective. The simulation result reveals that DTC for the five-level inverter fed IM drive gives a rapid dynamic response, lower voltage and current THDs, and much less flux and torque distortion. The simulation is carried out in MATLAB Simulink (R2014).
Nasreddine Attou, Sid-Ahmed Zidi, Samir Hadjeri, Mohamed Khatir,
Volume 19, Issue 3 (September 2023)
Abstract
Demand-side management has become a viable solution to meet the needs of the power system and consumers in the past decades due to the problems of power imbalance and peak demand on the grid. This study focused on an improved decision tree-based algorithm to cover off-peak hours and reduce or shift peak load in a grid-connected microgrid using a battery energy storage system (BESS), and a demand response scheme. The main objective is to provide an efficient and optimal management strategy to mitigate peak demand, reduce the electricity price, and replace expensive reserve generation units. The developed algorithm is evaluated with two scenarios to see the behavior of the management system throughout the day, taking into account the different types of days (weekends and working days), the random profile of the users' demand, and the variation of the energy price (EP) on the grid. The simulation results allowed us to reduce the daily consumption by about 30% to 40% and to fill up to 12% to 15% of the off-peak hours with maximum use of renewable energies, demonstrating the control system's performance in smoothing the load curve.
Arsen Ahmed, Hüseyin Demirel,
Volume 19, Issue 4 (December 2023)
Abstract
In the past twenty years, low-voltage and power design have gained attention in analog VLSI design, particularly for high-performance and portable integrated circuits (ICs). Because of the increasing density of large-scale integration, a single silicon A.S.I. chip could have thousands or even millions of transistors on it. A rise in integration levels led to the development of Fin-type Field Effect Transistor (FinFETs) technology. In this research, an improved circuit design for a floating active inductor (FAI) and quadrature sinusoidal oscillator (QSO) is implemented employing only two active filters, the Z-copy-Voltage Differential Transimpedance Amplifier (Zc-VDTA). The purpose of the FAI is to contain two Zc-VDTA and one resistor with a ground capacitor, and it is easy to integrate the parameters of the Zc-VDTA bias current (IB) through the adjustment of the circuit. In order to verify the dependability of the circuits designed using floating active inductance circuits, a Butterworth fourth-order low-pass filter was created via component replacement. All the simulations have been carried out on 7 nm using linear technology SPICE, and cadence virtuoso tool.
Mohamed Khalaf, Ahmed Fawzi, Ahmed Yahya,
Volume 20, Issue 1 (March 2024)
Abstract
Cognitive radio (CR) is an effective technique for dealing with scarcity in spectrum resources and enhancing overall spectrum utilization. CR attempts to enhance spectrum sensing by detecting the primary user (PU) and allowing the secondary user (SU) to utilize the spectrum holes. The rapid growth of CR technology increases the required standards for Spectrum Sensing (SS) performance, especially in regions with low Signal-to-Noise Ratios (SNRs). In Cognitive Radio Networks (CRN), SS is an essential process for detecting the available spectrum. SS is divided into sensing time and transmission time; the more the sensing time, the higher the detection probability) and the lower the probability of a false alarm). So, this paper proposes a novel two-stage SS optimization model for CR systems. The proposed model consists of two techniques: Interval Dependent De-noising (IDD) and Energy Detection (ED), which achieve optimum sensing time, maximum throughput, lower and higher. The Simulation results demonstrated that the proposed model decreases the, achieves a higher especially at low SNRs ranging, and obtains the optimum sensing time, achieving maximum throughput at different numbers of sensing samples (N) and different SNRs from -10 to -20 dB in the case of N = 1000 to 10000 samples. The proposed model achieves a throughput of 5.418 and 1.98 Bits/Sec/HZ at an optimum sensing time of 0.5ms and 1.5ms respectively, when N increases from 10000 to 100000 samples. The proposed model yields an achievable throughput of 5.37 and 4.58 Bits/Sec/HZ at an optimum sensing time of 1.66ms and 13ms respectively. So, it enhances the SS process than previous related techniques.
Shuvojit Kundu, Tuhel Ahmed, Jia Uddin,
Volume 21, Issue 1 (March 2025)
Abstract
This study aims to evaluate a cantilever beam type piezoelectric energy harvester operating on train-induced vibrations for powering Wireless Sensor Networks (WSNs) used in railway track monitoring systems. Harvester's behaviors under different conditions are simulated in MATLAB using the analytical model. Natural frequency, maximum deflection, and stress are calculated with greater precision using eigen frequency and stationary analysis using COMSOL Multiphysics. At a base excitation of 2 g and a resonant frequency of 4.38 Hz, the simulated results showed that the developed energy harvester prototype could generate up to 14 V of AC output voltage and 550 mW of output power. These findings highlight the promising potential of the proposed energy harvester for transforming train mechanical energy into electrical power. This energy harvester's viability and dependability for real-world applications in monitoring railway tracks are supported by developed analytical and simulation models.
