Mohamad Nur Khairul Hafizi Rohani
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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

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  • 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.
  • 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.
  • 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.
  • 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.
  • 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.
  • 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.
  • 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.
  • Publication
    Reduced Graphene Oxide UWB Array Sensor: High Performance for Brain Tumor Imaging and Detection
    ( 2023-01-01)
    Mohd Aminudin Jamlos
    ;
    Jamlos M.F.
    ;
    Wan Azani Wan Mustafa
    ;
    Othman N.A.
    ;
    Mohamad Nur Khairul Hafizi Rohani
    ;
    Syahrul Affandi Saidi
    ;
    Mohd Sharizan Md Sarip
    ;
    Mohd Al-Hafiz Mohd Nawi
    A low cost, with high performance, reduced graphene oxide (RGO) Ultra-wide Band (UWB) array sensor is presented to be applied with a technique of confocal radar-based microwave imaging to recognize a tumor in a human brain. RGO is used to form its patches on a Taconic substrate. The sensor functioned in a range of 1.2 to 10.8 GHz under UWB frequency. The sensor demonstrates high gain of 5.2 to 14.5 dB, with the small size of 90 mm × 45 mm2, which can be easily integrated into microwave imaging systems and allow the best functionality. Moreover, the novel UWB RGO array sensor is established as a detector with a phantom of the human head. The layers’ structure represents liquid-imitating tissues that consist of skin, fat, skull, and brain. The sensor will scan nine different points to cover the whole one-sided head phantom to obtain equally distributed reflected signals under two different situations, namely the existence and absence of the tumor. In order to accurately detect the tumor by producing sharper and clearer microwave image, the Matrix Laboratory software is used to improve the microwave imaging algorithm (delay and sum) including summing the imaging algorithm and recording the scattering parameters. The existence of a tumor will produce images with an error that is lower than 2 cm.
  • Publication
    Modelling of piezoelectric sensor based on ZnO material for partial discharge detection on power transformer
    ( 2020-01-01)
    Akashah N.A.
    ;
    Mohamad Nur Khairul Hafizi Rohani
    ;
    Afifah Shuhada Rosmi
    ;
    Muzamir Isa
    ;
    Baharuddin Ismail
    ;
    Kamarol M.
    ;
    Roslizan N.D.
    ;
    Khairul Nadiah Khalid
    Detection of partial discharge (PD) in early stages able to reduce the risk of decommissioning of high voltage (HV) equipment. However, the conventional method for PD detection are not suitable for on-site measurement due to electrical disturbance. One of the method in detecting PD signal is piezoelectric based acoustic emission (AE) sensors. In this project, an AE sensor is modelled to obtain a PD signal in the range of 10 – 300 kHz occurred in HV transformer and been found out by simulation and analytical approach. Two models of a piezoelectric sensor with different types of cantilever and different dimension variation starting from 4 mm to 15 mm are designed in the Finite element Method (FEM) in order to investigate the resonant frequency which is matched to the range of AE detection. Zinc oxide (ZnO) as a piezoelectric material is proposed in this project due to its high piezoelectric coupling and environmentally friendly compared to the others material which is harmful. Based on the simulation result, ZnO piezoelectric sensor with the length of 5 mm and thickness of 0.451 mm generates 0.0537 mV electrical potentials under the resonant frequency of 155.30 kHz which is in the range of AE detection technique.
  • Publication
    Selective Harmonic Elimination Pulse Width Modulation for Three-Phase Nine-Level Inverter Using Improved Whale Optimization Algorithm
    ( 2023-10-06)
    Bimazlim M.A.S.
    ;
    Baharuddin Ismail
    ;
    Muhammad Zaid Aihsan
    ;
    Rosnazri Ali
    ;
    Talib M.H.N.
    ;
    Muhammad Azhar Walter M.S.
    ;
    Siti Khodijah Mazalan
    ;
    Mohamad Nur Khairul Hafizi Rohani
    For many years, multilevel inverter (MLI) is a system well-known for converting DC voltage to AC voltage which is suitable for energy resources conversion for industrial power sources. With the help of Selective Harmonic Elimination Pulse Width Modulation (SHEPWM) switching technique, the output power from the MLI system is better efficiency with low Total Harmonics Distortion (THD). The SHEPWM switching technique is used to eliminate the lower order of the harmonics and reduces the Total Harmonics Distortion (THD) of the MLI system. Along with the optimization algorithms to solve difficult non-linear equations involving with SHEPWM, applying SHEPWM into MLI system helps to further improve the output power efficiency. Whale Optimization Algorithm (WOA) is one of the algorithms developed which capable of solving the non-linear equation and obtained suitable results for MLI. Additionally, many types of improvement done on WOA, called as Improved Whale Optimization Algorithms (IWOA) also developed to obtain better results compared with WOA. Developed in a MATLAB environment, a proposed IWOA is applied to solve the equation and compared with WOA. The results show that the proposed IWOA capable of achieving higher probability with fast convergence speed reaching global optimal compared to WOA. With the proposed approach, the IWOA efficiently computed required switching angles, to eliminate the selective lower-order harmonics for different modulation indices (Ma). In this paper, the proposed IWOA is performed on a three-phase nine-level cascaded H-bridge multilevel inverter (CHBMLI) for a wide range of modulation indexes between 0.1 until 1. The results show the eliminations of 5th, 7th, and 11th harmonics from the output of the three-phase nine-level MLI system thus reducing THD from the system up to 5.82%.