Mohamad Nur Khairul Hafizi Rohani
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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
    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
    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
    Wireless Rogowski coil sensor based on partial discharge detection signal for on-line condition monitoring in the medium voltage power cables
    ( 2017)
    Mohamad Nur Khairul Hafizi Rohani
    Partial discharge (PD) measurement provide a valuable information for assessing the insulation health in high voltage (HV) power system. In this research, a novel wireless Rogowski coil (RC) sensor based on PD detection in the medium voltage (MV) power cables is presented. This research is divided into three sections which are RC sensor development, pre-filtering technique and wireless integration. A series of investigations on sensitivity and bandwidth for four types of RC sensors was demonstrated. The prototype development first was carried out with the assistance of SolidWorks 3 dimension (3D) computer aided design (CAD) software and MakerBot 2X 3D printer. Subsequently, the sensors were modeled and simulated using Electromagnetic Transient Program-Alternative Transient Program (EMTP-ATP) software environment based on the lumped parameter identification. A single-end measuring technique was used as an on-line PD monitoring system on the three-phase medium voltage underground cross-link polyethylene (XLPE) insulated power cable with a 240 mm2 nominal area copper conductor. In order to verify the simulation results, an experimental measurement was carried out. This experiment was repeated concurrently for each design of the RC sensors and the precise selection for the best sensor is paramount. In this case, the results indicated that rectangular geometrical shape performed better with regard to the detection of the PD signal. The rectangular shapes of RC sensor has been selected in order to compare with the conventional RC sensor. Double-end technique measurement has been used where two of RC sensor is placed on the certain distance to analyse the propagation velocity and arrival time of PD signal captured by the sensor based on the different size of XPLE power cables. The analysis on accuracy of double-end and multi-end PD location technique have been conducted. The results between double-end and multi-end technique have 0.138 % and 0.026 % percentage error of PD location respectively. An experiment has been conducted in order to evaluate the effect of unshielded, shielded RC sensor and terminating resistance, 𝑅𝑡. The 𝑅𝑡 is a part of parameter which can improve the performance of RC sensor. An operational amplifier (op-amp) and active Butterworth high-pass filter which has been designed using Sallen-key topology that is used to amplify and suppress the noise of output signal from RC sensor in the second section. The integration of RC sensor into wireless communication system has been discussed in the final section. High speed analog to digital converter (ADC) device is required to sample the PD signal due. However, the conventional ADC in the market is expensive in high speed rate. Thus, Sigma-Delta (ΣΔ) ADC topology is developed in Altera DE0-Nano board. Peak detection with threshold technique is introduced in this section. Then, the data transmitted wirelessly to the server unit using radio frequency (RF) module as a transceiver and Altera DE2-115 board is used as a server unit. In order to achieve the accurate digital sampling of high frequency PD signal, the N-bit resolution is paramount. The finding of this analysis, 4-bit resolution is selected in this research as the best resolution for the ΣΔ ADC to sampling the PD signal.
  • Publication
    Niblack algorithm modification using maximum-minimum (Max-min) intensity approaches on low contrast document images
    ( 2020-01-01)
    Wan Azani Wan Mustafa
    ;
    Wan Khairunizam Wan Ahmad
    ;
    Mat Yusoff A.S.
    ;
    Syed Zulkarnain Syed Idrus
    ;
    Mohamad Nur Khairul Hafizi Rohani
    In recent decades, detection or segmentation has been one of the major interesting research subjects due to the analysis of the information. However, most of the historical document has degraded and low contrast problem. Recently, many binarization methods were proposed in order to segment the text region from the background region in the low-quality image. In this paper, an improved binarization method was inspired by Niblack method was presented. The modification focuses to find the optimum threshold value by using the Maximum-Minimum intensity technique. The main target is to reduce the unwanted detection image and increase the resultant performance compared to the original Niblack method. The proposed method was applied to the document images from H-DIBCO 2012 and H-DIBCO 2014 dataset. The results of the numerical simulation indicate that the target was achieved by the F-Measure by F-measure (58.706), PSNR (10.778) and Accuracy (86.876). This finding will give a new benchmark to other researchers to propose an advance binarization method.
  • Publication
    Pap Smear Image Analysis Based on Nucleus Segmentation and Deep Learning – A Recent Review
    ( 2023-02-01)
    Alias N.A.
    ;
    Wan Azani Wan Mustafa
    ;
    Mohd Aminudin Jamlos
    ;
    Ismail S.
    ;
    Alquran H.
    ;
    Mohamad Nur Khairul Hafizi Rohani
    Cervical cancer refers to a dangerous and common illness that impacts women worldwide. Moreover, this cancer affects over 300,000 people each year, with one woman diagnosed every minute. It affects over 0.5 million women annually, leading to over 0.3 million deaths. Recently, considerable literature has grown around developing technologies to detect cervical cancer cells in women. Previously, a cervical cancer diagnosis was made manually, which may result in a false positive or negative. Automated detection of cervical cancer and analysis method of the Papanicolaou (Pap) smear images are still debated among researchers. Thus, this paper reviewed several studies related to the detection method of Pap smear images focusing on Nuclei Segmentation and Deep Learning (DL) from the publication year of 2020, 2021, and 2022. Training, validation, and testing stages have all been the subject of study. However, there are still inadequacies in the current methodologies that have caused limitations to the proposed approaches by researchers. This study may inspire other researchers to view the proposed methods' potential and provide a decent foundation for developing and implementing new solutions.
  • Publication
    Location Technique based on Multiple Partial Discharge Signal in 11kV Underground Power Cable using EMTP-ATP Software
    ( 2021-03-09)
    Halim M.I.A.M.
    ;
    Mohamad Nur Khairul Hafizi Rohani
    ;
    Rosle N.
    ;
    Rosmi A.S.C.
    ;
    Yii C.
    ;
    Wan Azani Wan Mustafa
    Power cables are very critical in electrical power systems as power cables failure can interrupt the electrical flow due to unexpected power failure. There are a few sorts of partial discharge (PD) estimations gadgets in the market. For instance, PD can be distinguished by utilizing Rogowski coil (RC) sensors in the disconnected procedure. The current issue PD signal does not usually occur as a single source. Thus, the analysis of multiple PD sources is required to ensure that the cable insulation is in a healthy condition. PD location technique based on multiple signals in 11kV underground power cable was conducted in this research to estimate the accurate location of the PD signal. Modelling of single power cable in a distance of 10km with the RC sensor is installed at several distances to capture the PD signal that travels along the power cable. By selecting the distance between six RC sensors and synchronous multiple PD signal, the design of the power system has been constructed by using EMTP-ATP software. Multi-point technique based on time difference of arrival (TDOA) was performed in the single line power cable to obtain the PD location. The measurement using multi-point of RC sensor technique is preferred based on the conditions due to the value of velocity elimination. Based on the results, the accurate location of PD Source 1 is detected 501 m along RC sensor A1 to RC sensor A3. In contrast, PD source 2 has been detected 2800.15 m along RC sensor A4 to RC sensor A6 with the percentage error of 0.2% and 0.0053%, respectively. The findings show that the location of multiple PD signal that occurred along the line cable can be detected accurately by using the multi-point technique and TDOA. Hence, the performance of the power system has been improved.
  • Publication
    Overview of Segmentation X-Ray Medical Images Using Image Processing Technique
    ( 2020-06-17)
    Wan Azani Wan Mustafa
    ;
    Salleh N.M.
    ;
    Syed Zulkarnain Syed Idrus
    ;
    Mohd Aminudin Jamlos
    ;
    Mohamad Nur Khairul Hafizi Rohani
    Image processing techniques have been used in a wide variety of applications nowadays to enhance the quality of raw image data. Today, image segmentation or detection of x-tray medical imaging is very popular and challenges task in order to improve the diagnosis and analysis result. An x-ray image is one of the oldest photographic films that is mostly used in medical diagnosis and treatment. An x-ray image is a very useful modality for the physicians and doctors to determine and analyze the bone fracture, which is an important symptom used for diagnosis, but x-ray produces an only medium quality image, which will normally affect the information of the image. This article provides a review study of the medical image segmentation. Based on this study, the advantages and drawback each method clearly explained. This article presents an exhaustive review of these studies and suggests a direction for future developments in order to propose segmentation methods.
  • Publication
    Review of Edge-based Image Segmentation on Electrical Tree Classification in Cross-linked Polyethylene (XLPE) Insulation
    ( 2021-06-11)
    Mohd Annuar Mohd Isa
    ;
    Mohamad Nur Khairul Hafizi Rohani
    ;
    Baharuddin Ismail
    ;
    Afifah Shuhada Rosmi
    ;
    Isa M.
    ;
    Wan Azani Wan Mustafa
    ;
    Kamarol M.
    ;
    Mansor N.S.
    ;
    Nazar N.S.M.
    Electrical trees are the degradation events most linked with partial discharge (PD) activity in cross-linked polyethylene (XLPE) insulation of high voltage (HV) cables. To investigate tree structures and forms, study of electrical tree structures for morphological analysis often carried out using optical microscopy. However, since the noise induced by the occlusion and illumination, as well as by non-uniform intensity either from optical device's setting or the non-standard readout procedure, causes the deterioration of the original microscopy images, resulting in critically loses of information pertaining the tree structures making it difficult to obtained accurate measurement. Image segmentation is one of the potential solutions as it is well-suited for extracting information or certain features from microscopy images. This paper provides review of several segmentation techniques applied on the classification of electrical tree image acquired through lab environment. The works can be separated into three stages. The first step includes the preparation of samples and collection of treeing images by means of real-time microscopy observations. The captured data would then be pre-processed to achieve image binarization. In the next step, image segmentation process is conducted using existing edge-based segmentation methods including Prewitt, Roberts, Canny and Kirsch's templates. Later, comparative analysis will be performed using IQA (image quality assessment) metrics of accuracy, sensitivity, specificity, false-positive-rate and the Matthews Correlation Coefficient (MCC) as the final step. Performance-wise indicates that Kirsch's template able to segment most of the treeing pixels with accuracy of 97.63%, 63% sensitivity, 98.18% specificity and 0.46 MCC while showing low pixels misclassification. This result provides better justification for the integration of the edge-based technique in developing image segmentation algorithm well-matched for the electrical tree analysis in the future.
  • Publication
    Influence of Electrical Tree Characterization Change Based on Tree Inception Voltage in HV Solid Insulation
    ( 2023-01-01)
    Abdulah C.S.K.
    ;
    Rosmi A.S.
    ;
    Isa M.A.M.
    ;
    Baharuddin Ismail
    ;
    Mohamad Nur Khairul Hafizi Rohani
    ;
    Wan Azani Wan Mustafa
    ;
    Kamarol M.
    ;
    Yii C.C.
    ;
    Al-Attabi K.
    ;
    Almoussawi Z.A.
    To improve accuracy of degradation diagnosis for HV solid insulation, it is important to clarify the mechanism of inception and characterization of electrical-tree. In this paper, the study of influence between TIV and electrical tree characterization was done in a laboratory experiment by monitoring the TIV values and electrical tree propagation. This experiment involve using charged couple device camera (CCD) to capture and record the electrical tree thorough the experiment, a microscope to enlarge the needle tip that was inserted into the XLPE sample, and finally a personal computer to display the whole treeing growth process. Then, the voltage was injected into sample of XPLE constantly until the electrical tree start to initiate at the needle tip. As a result, the electrical tree take form based on the TIV, small number of TIV produce a less dense electrical tree compare to higher value of TIV. Additionally, denser electrical tree propagates faster and may lead to early breakdown.
  • Publication
    FEA-Based simulation of accelerated ageing in a power cable due to sustained partial discharge activities in a Spherical Cavity
    (Springer, 2023)
    Umar Musa
    ;
    Abdullahi A. Mati
    ;
    Abdullahi Mas'ud
    ;
    Gaddafi Sani Shehu
    ;
    Johnatan M. Rodríguez-Serna
    ;
    Saud J. Al-Shammari
    ;
    Mohamad Nur Khairul Hafizi Rohani
    ;
    Firdaus Muhammad-Sukki
    The reliability of electrical assets is greatly influenced by the quality of their insulations. Key power installations such as power cables are manufactured with polymer-based materials as part of their insulation system. However, accelerated ageing of equipment insulations due to manifestation of defect(s), and partial discharges (PDs) can offset the operation of these systems or even lead to breakdowns. In this study, a non-deterministic model to simulate the phenomenon of repetitive discharges in a spherical air-filled cavity within a practical power cable has been investigated. In addition, the work contributes to the understanding of PD behaviour and field distribution under different ageing conditions considering changes in cavity surface conductivity. First, a section of the practical XLPE cable containing the cavity is developed in 2D using COMSOL software, and a finite element analysis (FEA) of the electric field distribution within the cable insulation is performed. The magnitude of the cavity local field, that is enough to ignite a PD, is investigated. Alongside the COMSOL model, the activity of sustained internal PD is simulated in MATLAB by introducing a random sample generating factor and adjusting the model’s parameters to obtain something close to the practical results. Furthermore, the impact of continuous PD in the power cable under different cavity dimensions and surface conductivity is likewise investigated, and a phase resolved PD (PRPD) pattern is established. The result shows that the magnitude and number of PDs per cycle increase as the cavity size and its surface conductivity increase. Finally, when the cavity surface conductivity rises, the amplitude of the electric field generated by the surface charge distribution and the number of PDs per cycle approach their maximum values.