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All Journal International Journal of Electrical and Computer Engineering International Journal of Power Electronics and Drive Systems (IJPEDS) TELKOMNIKA (Telecommunication Computing Electronics and Control) Indonesian Journal of Electrical Engineering and Computer Science
Azli Yahya
Universiti Teknologi Malaysia
Computer Science & IT Control & Systems Engineering Electrical & Electronics Engineering

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 1 
Performance Evaluation of Rain Attenuation Models in a Tropical Station Abayomi Isiaka Yussuff; Nor Hisham Bin Haji Khamis; Azli Yahya
International Journal of Electrical and Computer Engineering (IJECE) Vol 4, No 5: October 2014
Publisher : Institute of Advanced Engineering and Science

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (254.09 KB)

Abstract

The non-uniformity of rainfall in both the horizontal and vertical directions makes the estimation of slant path attenuation complex. At frequencies above 10 GHz, the effects of attenuation and noise induced by rain are quite significant. One year satellite attenuation data were sourced from Malaysia East Asia Satellite at Ku frequency band; using ASTRO beacon signals to monitor and measure the slant path rain rate and attenuation at Universiti Teknologi Malaysia, Skudai. Four years’ one minute rain rate ground data at 0.01% of time exceeded were collected using rain gauge. The attenuation exceeded for other percentages of the time was obtained using statistical methods. Different rain attenuation prediction models were investigated and their performances compared. The validation results clearly suggested that the Breakpoint attenuation prediction model produced better results when compared with other models of interest.DOI:http://dx.doi.org/10.11591/ijece.v4i5.6583
EDM process through mathematical model Dana Dehghani; Azli Yahya; Nor Hisham Khamis; Ali Idham Alzaidi
International Journal of Power Electronics and Drive Systems (IJPEDS) Vol 10, No 2: June 2019
Publisher : Institute of Advanced Engineering and Science

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (309.023 KB) | DOI: 10.11591/ijpeds.v10.i2.pp874-881

Abstract

EDM is a well-established hole machining option with various advantages due to non-contact characteristics of the process. However, knowledge about the process is not enough for its more improvements. Exprimenal studies are costly and time consuming because of the complex nature of process. Therefore, process modeling is a good alternative to reduce the experimental expense related to the technology. This paper studys EDM process through mathematical model, which includes the precise insight into the interactive behavior of EDM system. The ignition, discharge and recovery phases of the model have been developed through MATLABs time domain analysis. Simulation result shows good agreement with expected profile of EDM spark. To verify the model, simulated material removal rates (MRRs) from series of simulation are compared with the experimental ones reported by previous researcher. Ability of the model to predict the dynamic behavior profile of the EDM system is successfully confirmed by low average percentage error in predicting MRR.
Electrical Discharge Machining Flyback Converter using UC3842 Current Mode PWM Controller Nazriah Mahmud; Azli Yahya; Trias Andromeda
International Journal of Power Electronics and Drive Systems (IJPEDS) Vol 5, No 2: 2014
Publisher : Institute of Advanced Engineering and Science

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Abstract

This paper presents a current mode Pulse Width Modulation (PWM) controlled Flyback converter using UC3842 for Electrical Discharge Machining current generator control circuit. Circuit simplicity and high efficiency can be achieved by a Flyback converter with current mode PWM controller. The behaviors of the system's operation is analyzed and discussed by varying the load resistance. Matlab sofware is used to simulate the Flyback converter where a prototype has been built and tested to verify it's performance. DOI: http://dx.doi.org/10.11591/ijpeds.v5i2.6680
Online video-based abnormal detection using highly motion techniques and statistical measures Ahlam Al-Dhamari; Rubita Sudirman; Nasrul Humaimi Mahmood; Nor Hisham Khamis; Azli Yahya
TELKOMNIKA (Telecommunication Computing Electronics and Control) Vol 17, No 4: August 2019
Publisher : Universitas Ahmad Dahlan

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.12928/telkomnika.v17i4.12753

Abstract

At the essence of video surveillance, there are abnormal detection approaches, which have been proven to be substantially effective in detecting abnormal incidents without prior knowledge about these incidents. Based on the state-of-the-art research, it is evident that there is a trade-off between frame processing time and detection accuracy in abnormal detection approaches. Therefore, the primary challenge is to balance this trade-off suitably by utilizing few, but very descriptive features to fulfill online performance while maintaining a high accuracy rate. In this study, we propose a new framework, which achieves the balancing between detection accuracy and video processing time by employing two efficient motion techniques, specifically, foreground and optical flow energy. Moreover, we use different statistical analysis measures of motion features to get robust inference method to distinguish abnormal behavior incident from normal ones. The performance of this framework has been extensively evaluated in terms of the detection accuracy, the area under the curve (AUC) and frame processing time. Simulation results and comparisons with ten relevant online and non-online frameworks demonstrate that our framework efficiently achieves superior performance to those frameworks, in which it presents high values for he accuracy while attaining simultaneously low values for the processing time.
Underwater Channel Characterization to Design Wireless Sensor Network by Bellhop Nima Bahrami; Nor Hisham Haji Khamis; Ameruddin Baharom; Azli Yahya
TELKOMNIKA (Telecommunication Computing Electronics and Control) Vol 14, No 1: March 2016
Publisher : Universitas Ahmad Dahlan

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.12928/telkomnika.v14i1.2454

Abstract

Acoustic underwater link due to low attenuation is employed for underwater sensor network (UWSN). Due to water changing physical properties and different environmental conditions, the sound propagation for every underwater channel are different. So, the most important parameters to design reliable UWSN are: the shadow zone determination, optimum nodes placement, high signal to noise ratio and more power efficiency of nodes. This paper simulates underwater channel for 7 KHz carrier frequency, with measured physical water properties and remote sensing data. Based on defined scenario, the research determines optimum nodes placement and link budget analysis based on bottom to surface acoustic link. The paper utilizes Bellhop acoustic toolbox as a simulator, GeoMapApp program to collects bathymetry data and Aviso+ database to determine wind speed on sea surface. As a result the paper based on simulation of sound propagation in channel and transmission loss determination in depth and range, finds the optimum nodes positions and link budget calculation to prove the results.
Nonlinear Servomotor in Single Pulse Simulation of Electrical Discharge Machining System Modeling Hassan Lee; Azli Yahya; Nor Hisham Khamis; Shahrullail Samion
Indonesian Journal of Electrical Engineering and Computer Science Vol 1, No 2: February 2016
Publisher : Institute of Advanced Engineering and Science

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.11591/ijeecs.v1.i2.pp319-328

Abstract

Electrical Discharge Machining, EDM is a nonconventional and high precision machining.  EDM system is considered a combination of servo system and EDM process. The servo system precisely controls the gap between electrode and workpiece for the continuous electrical discharges occurrence. Machining performance and stability depend on the performance of servo system. The EDM servo system usually modeled as a linear system, which ignores the nonlinearities of the motor. An assumption that the nonlinearities are insignificant in EDM system model may leads to modeling errors and result in poor control performance. In this study, nonlinear EDM servo system model was presented and the dynamic response of the model was analyzed and compared with the linear model. Simulation result shows a slightly difference in system response and a controller used in linear model is less efficient for a nonlinear EDM servo system model. The results are very useful for control strategy and can contribute to a better machining performance and stability of EDM applications.
Co-Authors Abayomi Isiaka Yussuff Ahlam Al-Dhamari Ali Idham Alzaidi Ameruddin Baharom Dana Dehghani Hassan Lee Nasrul Humaimi Mahmood Nazriah Mahmud Nima Bahrami Nor Hisham Bin Haji Khamis Nor Hisham Haji Khamis Nor Hisham Khamis Rubita Sudirman Shahrullail Samion Trias Andromeda