Mohamad Nur Khairul Hafizi Rohani
Thumbnail Image
Preferred name
Mohamad Nur Khairul Hafizi Rohani
Official Name
Mohamad Nur Khairul Hafizi, Rohani
Alternative Name
Hafizi Rohani, Mohamad Nur Khairul
Rohani, M. N.K.H.
Main Affiliation
Scopus Author ID
57189241581
Researcher ID
G-4075-2017

Research Output

Filters

48
Reset filters

Settings
Now showing 1 - 10 of 48
Thumbnail Image
Publication

Comparison of Image Restoration using Median, Wiener, and Gaussian Filtering Techniques based on Electrical Tree

2021-01-01 , Abdulah C.S.K. , Mohamad Nur Khairul Hafizi Rohani , Baharuddin Ismail , Isa M.A.M. , Afifah Shuhada Rosmi , Wan Azani Wan Mustafa

Electrical treeing lead to a major cause of a breakdown in solid insulation. Thus reduced solid insulation performance by degrading the insulation. Hence, it is important to study the electrical treeing and learn the root cause of the treeing formation. In this paper, the performances of median, wiener, and gaussian filters in restoring noisy images are studied based on electrical tree images. The electrical tree colour images is being transform into grayscale images, noisy images using impulse noise (salt and pepper), and finally motion blur are applied. Even though, there are several number of filters available, this paper focus on median, wiener, gaussian, and combination of the filters. In the end, comparison between these filters is made to study the efficiency using PSNR, SNR, and MSE in graph form.

View
Thumbnail Image
Publication

A study on copper and galvanized grounding performance using palm oil fuel ash as new additive material

2020-01-07 , Faudzi A.H.M. , Wooi Chin Leong , Ahmad N.A. , Syahrun Nizam Md Arshad @ Hashim , Afrouzi H.N. , Mohamad Nur Khairul Hafizi Rohani

This paper aimed to study the improvement of grounding performance by reducing the grounding electrode resistance using palm oil fuel ash as the backfill. This is achieved by mixing the soil with a specific portion of palm oil fuel ash and obtains the grounding electrode resistance value by using Three Pin Method. In order to obtain the grounding electrode resistance, the mixture of palm oil fuel ash and soil were compacted and installed with electrodes. Two types of electrodes were connected to measuring device which is Kyoritsu Digital Earth Tester Model 4105A and grounding electrode resistance values were displayed. The two types of electrodes used in this study were copper and galvanized steel electrodes. It was found that by adding palm oil fuel ash to the soil, the grounding performance can be improved to at least 90% and above for both copper and galvanized steel electrodes. The palm oil fuel ash is very effective in improving the grounding performance at low cost and environmentally friendly.

View
Thumbnail Image
Publication

A Smart Image Enhancement Monitoring System Using Graphical User Interface (GUI)

2020-06-17 , Sam S. , Wan Azani Wan Mustafa , Syed Zulkarnain Syed Idrus , Mohd Aminudin Jamlos , Mohamad Nur Khairul Hafizi Rohani , Wooi Chin Leong

Image filtering is one of the methods used in image processing. It is also can be called as image enhancement. Filter help the problems of the image display and can improvise the quality of the image. The problems that always happened in the image is illumination, noise and under-light images. In addition, these problems also caused a few troubles for image recognition for the daily life of certain people for their work. The purpose of this study is to apply the mathematical algorithm of the filters, identifying the best method of the filters and simulate the result of the image quality assessments in Graphical User Interface (GUI) and Global System for Mobile Notification (GSM). Basically, image processing methods have specific mathematical algorithms. That is the main difference between these methods. For this paper, two types of image have been chosen which is document image and medical image. There were a few methods that were selected in this project. It is a high pass filter, low pass filter, and high boost filter. Thus, homomorphic filtering was applied to that filter. Then, the enhanced images would be simulated to the selected parameters of image quality assessments (IQA). The selected parameter of the image quality assessment is a global contrast factor (GCF) and signal to noise ratio (SNR). If the value of the parameters satisfies its characteristic, the method would be selected as the most suitable method for the image. Meanwhile, the best result will be selected as the best image for this study.

View
Thumbnail Image
Publication

Influence of PD source and AE sensor distance towards arrival time of propagation wave in power transformer

2020-01-07 , Khairul Nadiah Khalid , Mohamad Nur Khairul Hafizi Rohani , Baharuddin Ismail , Muzamir Isa , Afifah Shuhada Rosmi , Wooi Chin Leong , Yii C.C.

Partial discharge (PD) often begins with cracks or gas-filled voids in solid insulation or with gaseous bubbles in liquid insulation. These presences can degrade the quality of insulator. PD detection can identify these cracks at high voltage equipment such as power cables and power transformer at the early stage. One of PD detection methods is acoustic emission (AE) detection. PD produces an ultrasonic signal that can be captured by an AE sensor. The signal captured is then analysed by capturing the time of the receiving signal onto the sensor. The information related to time can be used for allocating the PD for maintenance purpose. This paper shows the influence of the distance between PD source and the AE sensor towards the arrival time of propagation wave in power transformer. In this study, the four placements of sensors were analysed by having three possible PD sources to represent the variety of distances between the PD source and the sensor. The simulated signal is generated by MATLAB and the arrival time is captured using time of arrival (TOA) method. The time captured and the distance between the PD source and arrival time showed that the relationship is proportional to one another.

View
Thumbnail Image
Publication

Zero Index Metamaterial of Simulated Split Ring Resonator Element

2022-01-01 , Mohd Aminudin Jamlos , Othman N.A. , Wan Azani Wan Mustafa , Hasliza A Rahim @ Samsuddin , Alfilh R.H.C. , Mohamad Nur Khairul Hafizi Rohani

Split Ring Resonator of Zero Index metamaterial element has been proposed. The Split Ring Resonator consists of four loops; a more modest loop inside a bigger one, with openings, consolidated into each loop at the far edges, and an expansion of the rectangular loop to realize the gap (split) which permits control of the capacitance. The split ring is designed and simulated using sophisticated simulation software to have accurate simulation results. Two waveguide ports of terminals have been used within the assigned unit cell boundary for the simulated purpose. A parametric study has taken place for the width and length of the split ring resonator to find the optimized design to have zero index at the desired frequency of 2.7 GHz. The optimized dimensions of the split ring resonator are 7.29 mm and 6.0 mm for width and length respectively. The split ring resonator successfully recorded zero index (phase) at the desired frequency of 2.7 GHz for low-frequency applications specifically for GHz ranges.

View
Thumbnail Image
Publication

Protection Relay Setting based on Overcurrent Phenomena in Commercial Building

2024-03-01 , Isyraq Faizzi Mohammad , Mohamad Nur Khairul Hafizi Rohani , Afifah Shuhada Rosmi , Baharuddin Ismail , Muhamad Hatta Hussain , Abdullahi Abubakar Mas’ud , Firdaus Muhammad-Sukki

Nowadays, every single distribution system needs to install an appropriate relay to keep the system safe. The operational and commonly recommended relay for distribution systems is the overcurrent (OC) relay. Throughout the distribution system, the protective relay is one of the methods that can detect and protect the location according to its observation from any fault from abnormal activity. Note that time coordination between the protective equipment relay needs to be a minimum of time interruption to prevent faults occurs. The ideal setting for all coordination protection relays is necessary to protect the device against electrical failure and interference. This paper analyzes the real results data collected for the selected commercial building of an OC relay implemented in a distribution board for high voltage and low voltage downward at a commercial building. All the parameters need to be clarified first before testing has been made and measurement is carried out using the MICROTEST 860 set. Based on the analysis, it proves that according to the IEC Standard of 0.10-time multiplier Setting (TMS) is practical to be used to obtain the operation time in seconds for the current curve set. Other than that, the results show that the normal inverse curve from manual calculation results is more accurate compared to the service setting (SS) made based on the incoming setting in a real commercial building. The case study for OC relay setting is related between current injection and time-tripping, which complies with the IEC 60255-3 standard using its formula. This method was applied to determine the characteristics of the curve. Hence, this research successfully determined the proper methods for the OC relay setting for the power distribution system. Besides, the feasibility and efficiency of OC relay data transmission are tested and checked successfully to implement the measurement method in the relay coordination study.

View
Thumbnail Image
Publication

Electrical Tree Investigation on Solid Insulation for High Voltage Applications

2021-01-01 , Abdulah C.S.K. , Mohamad Nur Khairul Hafizi Rohani , Baharuddin Ismail , Isa M.A.M. , Afifah Shuhada Rosmi , Wan Azani Wan Mustafa , Kamarol M.

Electrical treeing is a major cause of a breakdown in solid insulation cable. This phenomenon reduced aging by degrading the insulation, leading to failure in the high voltage materials. The most common experimental set-up in studying the electrical tree is using a needle electrode to initiate the treeing image. Different types of needle and insulation material had been studied from the previous experiment. This paper review the method used to investigate tree growth and its technique to capture the treeing image. Based on this review, several causes delay the treeing process in the needle embedded experiments. In contrast, 2D image processing is the most frequent image developed in the electrical tree on solid insulation.

View
Thumbnail Image
Publication

IR 4.0: Smart Farming Monitoring System

2023-01-01 , Nasir M.F. , Mohd Aminudin Jamlos , Wan Azani Wan Mustafa , Mohamad Nur Khairul Hafizi Rohani , Muhammad Zaid Aihsan , Habelalmateen M.I. , Ramadan G.M.

The Internet of Things is the current and future of every field that effects everyone's life by making everything smart. The development of Smart Farming Monitoring with the use of the Internet of Things, changes conventional farming methods by not only making them optimal but also effective for farmers and reducing crop wastage. Therefore, Smart Farm Monitoring of IR 4.0 Implementation is designed to provide a system for monitoring environmental factors in farming in real time. This product will help farmers by creating an easy-to-use user view so users can view data. By implementing various types of sensors and applications such as Raspberry Pi 4B as its main controller, Temperature & Humidity sensor (DHT22), Capacitive Soil Moisture sensor, MQ135 sensor, Light Intensity sensor, ThingSpeak and ThingView, farmers will can monitor parameters and this data will be sent to the database for real-time display and storage purposes. The project is expected to create a smart environment conducive to agriculture and reduce labour costs and water wastage and increase productivity and efficiency. The system is achieved, as the intelligent monitoring of agriculture allows real-time monitoring with less time.

View
Thumbnail Image
Publication

5.8 GHz Circularly Polarized Rectangular Microstrip Antenna Arrays simulation for Point-to-Point Application

2022-11-01 , Mohd Aminudin Jamlos , Sabri N.H.M. , Jamlos M.F. , Wan Azani Wan Mustafa , Syed Zulkarnain Syed Idrus , Mohamad Nur Khairul Hafizi Rohani , Khairul Najmy Abdul Rani , Mohd Al-Hafiz Mohd Nawi

In this paper, the design and simulation of rectangular microstrip antenna arrays for improving antenna gain is performed for point-to-point application. The circular polarization is proposed to restrict the limitation of linear polarization which is less reliable in base station antenna. The circular polarization antenna is made to allow the receiver constantly to receive the power at any wave angle and make the transmission between two antennas are more constant. The proposed design is composed of four elements microstrip antenna with an array configuration operating at 5.8 GHz. Each element is constructed from four truncated arrays radiating elements and an inclined slot on each patch which capable to achieve circular polarized capability. The design of the 2x1 and 2x2 of rectangular microstrip array antenna was implemented from the design of single rectangular patch antenna as the basic building element. The designed 2x1 and 2x2 array were fed by microstrip transmission line which applied a technique of quarter wave impedance matching. The antenna design was etched on Rogers RT 5880 substrate with 2.1 and 1.53 mm of dielectric constant and thickness respectively. All the designed structure were simulated in CST software. The main results of the designed antennas were compared in terms of gain, axial ratio and return loss. Based on the return loss simulation results, the designed antennas resonated exactly at the desired resonant frequency of 5.8 GHz which indicates good antenna designs. Compared to the single patch antenna having an antenna gain of 8.26 dB, the 2x1 and 2x2 arrays achieved a gain of 10.24 dB and 13.29 dB respectively. The results show that the designed rectangular microstrip antenna arrays have an improved gain performance over the single patch antenna.

View
Thumbnail Image
Publication

Multiple Partial Discharge Signal Classification Using Artificial Neural Network Technique in XLPE Power Cable

2023-02-01 , Halim M.I.A. , Razaly N.Z.M. , Mohamad Nur Khairul Hafizi Rohani , Norfadilah Rosle , Auni W.N. , Afifah Shuhada Rosmi , Muhammad Zaid Aihsan , Mohd Aminudin Jamlos , Mas’ud A.A.

According to partial discharge (PD) damage in the electrodes that are not entirely bridging, the presence of PD in the high voltage (HV) power cable might lead to insulation failure. PD defects can damage cross-linked polyethylene (XLPE) cables directly, which is one of the most critical electrical issues in the industry. Poor workmanship during cable jointing, aging, or exposure to the surrounding environment is the most common cause of PD in HV cable systems. As a result, the location of the PD signals that occur cannot be classified without identifying the multiple PD signals present in the cable system. In this study, the artificial neural network (ANN) based feedforward back propagation classification technique is used as a diagnostic tool thru MATLAB software in which the PD signal was approached to determine the accuracy of the location PD signal. In addition, statistical feature extraction was added to compare the accuracy of classification with the standard method. The three-point technique is also an approach used to locate PD signals in a single line 11 kV XLPE underground power cable. The results show that the statistical feature extraction had been successful classify the PD signal location with the accuracy of 80% compared to without statistical feature extraction. The distance between PD signals and the PD source affected the result of the three-point technique which proved that a lower error means a near distance between them.

View