Mohd Hafizuddin Mat
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Preferred name
Mohd Hafizuddin Mat
Official Name
Mohd Hafizuddin , Mat
Alternative Name
Mat, Mohd H.
Mat, Mohd Hafizuddin
Mat, M. H.
Main Affiliation
Scopus Author ID
54583921100
Researcher ID
GBL-6495-2022

Research Output
Now showing 1 - 7 of 7
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Publication

A brief review of the EMF interaction: Metal implantation and biological tissues

2017-01-01 , Mohd Hafizuddin Mat , Muzammil Jusoh , Hasliza A Rahim @ Samsuddin , Mohd Irwan Yusoff

In analyzing the near field for a device, such as a mobile phone used in close proximity to tissues, it is difficult to predict the electromagnetic field (EMF) and other characteristics, since certain parts of the mobile phone scatter and reflect the EMF. Moreover, the absorption of EMF in the lossy tissues mitigates as the radio frequency (RF) energy is absorbed by the tissue. In order to minimize the heating effect on human tissue caused by this absorption of RF energy by the human body, all communications equipment (CE) must comply with the guidelines that established the maximum power output of devices. Though RF emissions from CE are carefully measured, the probability exists that the RF characteristics are reformed somewhat when tissue that illuminated by RF energy embedded with implant, thereby increasing the specific absorption rate (SAR). The SAR is the fundamental metric for specifying RF absorption by tissues and it can be calculated at any location in the tissue.

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Publication

Advanced control strategies for managing circulating currents in islanded microgrid inverters

2025-06 , Mohd Hafizuddin Mat , Nur Hidayah Ramli , Nurul Husna Abd Wahab , Norezmi Md Jamal

In islanded microgrids, circulating currents among parallel inverters pose significant challenges to system stability and efficient power distribution. Traditional droop control methods often struggle to manage these currents effectively, leading to inefficiencies and potential system damage. This study introduces an advanced fuzzy-robust droop control strategy that integrates fuzzy logic with robust droop control to address these challenges. By incorporating fuzzy logic, the proposed strategy enhances the adaptability of droop control to varying system conditions, improving the management of circulating currents and ensuring more accurate power sharing among inverters. Comprehensive mathematical modeling and extensive simulation analyses validate the performance of this control strategy. The results show that the fuzzy-robust droop control method significantly outperforms conventional approaches, achieving up to a 70% reduction in circulating currents. This improvement leads to a substantial reduction in power losses and enhances the dynamic response under varying load conditions. Additionally, the strategy improves voltage and frequency regulation, contributing to the overall stability and reliability of the microgrid. The findings provide a robust solution to the longstanding issue of circulating currents, optimizing microgrid operations, and paving the way for more efficient and resilient distributed energy systems. The advanced control strategy presented in this study not only addresses critical challenges but also demonstrates the potential for innovative methodologies to meet the growing demands of future energy infrastructures, where reliability and efficiency are essential.

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Left-handed metamaterial wearable antenna at 5G frequency range for wireless body area network

2023 , Nur Hidayah Ramli , Muhammad Afif Farhan Lokman , Norfatihah Bahari , Liyana Zahid , Rashidah Che Yob , Mohd Hafizuddin Mat , Mohd Aminudin Jamlos , Laith H. Alzubaidi , Abbas Hameed Abdul Hussein

Wearable antennas are typically required to be small in weight, provide high bandwidth, high gain and efficiency, low price, and be installation-free for many modern applications. Due to the non-static human movement, an antenna with wide-angle scanning is necessary. This project is carried out by designing a small metamaterials wearable antenna at a 5G frequency range. The combination of left-handed metamaterial (LHM) and the wearable antenna is designed to operate for such a system. Results prove that the small wearable metamaterial antenna offers good performances where the gain is 5.8 dBi with an efficiency of 91.86% and provides an omnidirectional radiation pattern compared to the wearable antenna without LHM structure. The communication links of the antenna between the base station and the human body are investigated. The antenna can receive the signals for long distances may be up to 2 meters with wide angles. All the results will be a guideline while designing the systems in the future.

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Critical Review: Adaptive Pole Assignment PID Controller on DC-DC Converters

2020-03-20 , Husna A.W.N. , Mohd Hafizuddin Mat , Mohd Najib Mohd Yasin , Muzammil Jusoh , Mohd Irwan Yusoff , Mohamad Shukor Abdul Rahim , Esa S.M.

Recently, control usages of DC-DC converters have been widely investigated particularly in renewable energy; as the primary sources. Discovering the most appropriate control method to be applied in DC-DC converter topologies is the most significant interest of research and development in this field. Thus, the review is carried out in selecting a control method that capable to improve the functioning of the converters as well as reducing the effect of disturbances and load variances.

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Technologies of solar tracking systems: A review

2020-03-20 , Amelia A.R. , Mohd Irwan Yusoff , Safwati Ibrahim , Leow Wai Zhe , Mohd Hafizuddin Mat , Mohamad Shukor Abdul Rahim

Solar energy is abundantly in nature and sustainable energy resources around the world. The main challenge with the solar field is less amount of sun energy captured by using photovoltaic (PV) systems. The great performance of the PV systems can be achieved if the panel is kept perpendicular to the direction of the radiations of sun. Hence, solar tracker system is the method to keep the optimum position of the PV panel for always perpendicular to the solar radiation. This paper aims to review on various technologies of solar tracking to determine the best PV panel orientation. The various types of technologies of solar tracking system have been discussed which includes passive solar tracker, active solar tracker and chronological tracker system. The movement degrees of solar tracking system also have been addressed which consisting single-axis solar tracking system and dual-axis solar tracking system. This paper is also overviews the tracking techniques performance, construction, performance, advantages, and disadvantages of existing solar tracking system. The limitations of solar tracking systems are also highlighted for future action improvement. Through this research studies, the most favorable solar tracking system was identified as active solar tracker with the dual axis rotation.

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Determination of soft starter firing angle performance to mitigate motor high inrush current using current limitation method

2020-03-20 , Mohamad Shukor Abdul Rahim , Azizan, Muhammad Mokhzaini , Mohd Irwan Yusoff , Mohd Hafizuddin Mat , Nur Irwany Ahmad , Noor Fazliana Fadzail , Md Esa, Suhaireza Binti

Inrush current in the simplest form can also be determined as current drawn by an induction motor during startup period. This starting current will shoot up about 5 to 7 times the rated current. However, this high current usually occur in the starting period only. To overcome this, several techniques can be implemented to reduce the high current. The configuration of soft starter just involving some power semiconductor device act as switches that control the current flow from power source to the motor. The switches is in form of thyristor and are connected back-to-back because the system conduct in AC system. The current output can be controlled by varying the firing angle. This changing of firing angle will be managed by a firing angle control circuit. This soft starter was connected between power source and motor. The thyristors that built in soft starter act like a gate to control the voltage applied to the motor. The firing angle for current limitation soft starter was changed to several angle and what can be concluded that the high current succeed to mitigate with increasing the firing angle. The current drawn for this type of starter is steadily constant. The lower current during starting took longer time for motor to reach its rated speed. This type of starter successfully reduces inrush current about 42 percent. Finally what can be concluded is that the soft starter was proven to mitigate inrush current. Type of soft starter that going to implement is depending on the application of motor. When the application need to control the torque is more suitable to use current limitation soft starter because the current is steadily control.

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Specific absorption rate in the human head due to metal-frame glasses and ear Prosthesis

2015 , Mohd Hafizuddin Mat

The research in this thesis involves the investigation of the specific absorption rate (SAR) in a human head model exposed to electromagnetic fields. The SARs (1-g and 10-g) were compared inside various models of the human head. Investigation is aimed at the study of the effect of the use of a realistic implant retained prosthetic ear attached to the side of the head and metal-frame glasses. A set of dipole antennas operating at a common frequency of 900, 1800 and 2100 MHz were rotated to investigate the effect of frequency and polarization. Two situations were considered in the thesis; radiation at the front of the face, and at the side of the head. Initial studies were conducted using a simplified model of the head and metal object to minimize the duration of the simulation. Four types of simple geometrical head were used; brick, cylindrical, spherical and elliptical cylinders were simulated with and without the simple shape of the nose to investigate its possible effects. At the same time, a straight metal rod was initially employed to represent the metal-frame glasses. The parameters were further expanded to the different conductivities of the metal rod, the dimensions of a model of the head, the curvature of the rod and the radii of the rod. In the side radiation case, the investigation of the ear prosthesis was initiated by looking at the effect of different dielectric properties of the artificial ear. Moreover, the combined use of these metal objects with realistic shapes of both glasses and implant (ear) were investigated in detail using homogeneous and heterogeneous models of a human head. The results suggest that different sections of the implant resonate depending on the frequency and polarization, and furthermore, demonstrate that this real implant is a complex scattering element. The implant focuses and reflects the incident radio frequency (RF) energy. The nearby tissue of the head will also have a secondary dielectric loading effect. The relative enhancement on the SAR10g due to the implant was much smaller. The SAR distribution shows that the increase in the SAR due to the metallic implant is extremely local with regards to the implant. This explains the change in the SAR1g and the much smaller changes to the 10g SAR. However, the metal-frame glasses selected in this investigation had given a negative significant increment of SARs at any orientation of the dipole and frequency chosen. Overall, with regard to the ear prosthesis, exposure to 900 MHz from any device adjacent to the implant may cause harm. It also is suggested that patients with ear prostheses should not be exposed to any near-body communication at any frequency range, because there is evidence that metal implanted inside certain materials has different behavior from the same metal that has not been implanted in any material.

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