Browsing by Type "Journal"
  • Publication
    132kV oil impregnated paper bushing transformer-design by CAD, analysed by FEM
    ( 2019-12-01)
    Rahman N.A.
    ;
    Isa M.
    ;
    Rohani M.N.K.H.
    ;
    Hamid H.A.
    ;
    Al Bakri Abdullah M.M.
    The Electric Field and Voltage Distribution (EFVD) are an important parameter for assessing high voltage bushing transformer performance. However, conducting laboratories experiment is dangerous, difficult and expensive due to several aspects. Therefore, Finite Element Method (FEM) software is the best option used as a tool for the assessment of bushing transformer's performance in terms of EFVD. But, before an assessment of analysis could be carried out, an accurate model of bushing transformer must first to be designed. In this research, Computer Aided Design (CAD) software has been employed to design the 145kV bushing transformer based on actual dimension. Upon completion, the design has been exported to FEM software for further analysis. In FEM software, measurement and analysis of electric field and voltage distribution (EFVD) have been carried out. The measurements are performed at various locations of bushing transformer such as of the porcelain surface (both air and oil side), along with aluminum foils, and at oil-impregnated paper (OIP). The results obtained have been compared with other researchers and it is found very satisfactory.
  • Publication
    2.45 GHZ wearable rectenna array design for microwave energy harvesting
    ( 2019-05-01)
    Shawalil S.
    ;
    Abdul Rani K.N.
    ;
    Rahim H.A.
    This paper presents a design of a wearable textile microstrip patch rectifying antenna (rectenna) array operating for Wireless Body Area Network (WBAN) at the center frequency, f c of 2.45 GHz. Precisely, jeans or denim with the relative permittivity, = 1.70 and thickness of 1.00 mm is chosen as a substrate attached to SheildIt Super as a conductive material with the thickness, h of 0.17 mm and conductivity of 6.67 10 5 S/m, respectively. In the first stage, a microstrip patch antenna array layout with the inset fed technique is designed and simulated by using the Keysight Advanced Design System (ADS) software. In the second stage, a wearable textile microstrip patch antenna array is fabricated, integrated, and hidden inside the jeans fabric. In the third stage, the rectifier circuit layout on the Flame Retardant-4 (FR-4) Printed Circuit Board (PCB) with the dielectric constant, = 4.7, thickness, h = 1.6 mm, and loss tangent, δ = 0.018 that can generate Radio Frequency-Direct Current (RF-DC) conversion is designed and simulated using the ADS software Each simulation result and fabrication measurement shows that the designed antenna array characteristics are suitable for an Industrial, Scientific, and Medical radio (ISM) band by having the reflection coefficient, S 11 less than-10 decibel (dB) at the respective resonant frequency, f r . Moreover, through simulation, the output DC voltage for the bridge rectifier circuit is from 132 mV to 5.01 V with the corresponding Power Conversion Efficiency (PCE) between 3.48% and 50.20% whereas for the voltage doubler rectifier, the output DC voltage is from 417 mV to 2.91 V with the corresponding PCE between 34.78% and 53.56%, respectively.
  • Publication
    2D LiDAR Based Reinforcement Learning for Multi-Target Path Planning in Unknown Environment
    ( 2023-01-01)
    Abdalmanan N.
    ;
    Kamarulzaman Kamarudin
    ;
    Muhammad Aizat Abu Bakar
    ;
    Mohd Hafiz Fazalul Rahiman
    ;
    Ammar Zakaria
    ;
    Syed Muhammad Mamduh Syed Zakaria
    ;
    Latifah Munirah Kamarudin
    Global path planning techniques have been widely employed in solving path planning problems, however they have been found to be unsuitable for unknown environments. Contrarily, the traditional Q-learning method, which is a common reinforcement learning approach for local path planning, is unable to complete the task for multiple targets. To address these limitations, this paper proposes a modified Q-learning method, called Vector Field Histogram based Q-learning (VFH-QL) utilized the VFH information in state space representation and reward function, based on a 2D LiDAR sensor. We compared the performance of our proposed method with the classical Q-learning method (CQL) through training experiments that were conducted in a simulated environment with a size of 400 square pixels, representing a 20-meter square map. The environment contained static obstacles and a single mobile robot. Two experiments were conducted: experiment A involved path planning for a single target, while experiment B involved path planning for multiple targets. The results of experiment A showed that VFH-QL method had 87.06% less training time and 99.98% better obstacle avoidance compared to CQL. In experiment B, VFH-QL method was found to have an average training time that was 95.69% less than that of the CQL method and 83.99% better path quality. The VFH-QL method was then evaluated using a benchmark dataset. The results indicated that the VFH-QL exhibited superior path quality, with efficiency of 94.89% and improvements of 96.91% and 96.69% over CQL and SARSA in the task of path planning for multiple targets in unknown environments.
      1
  • Publication
    3D grape bunch model reconstruction from 2D images
    ( 2023-12-01)
    Woo Y.S.
    ;
    Li Z.
    ;
    Tamura S.
    ;
    Buayai P.
    ;
    Nishizaki H.
    ;
    Makino K.
    ;
    Latifah Munirah Kamarudin
    ;
    Mao X.
    A crucial step in the production of table grapes is berry thinning. This is because the market value of table grape production is significantly influenced by bunch compactness, bunch form and berry size, all of which are primarily regulated by this task. Grape farmers must count the number of berries in the working bunch and decide which berry should be eliminated during thinning, a process requiring extensive viticultural knowledge. However, the use of 2D pictures for automatic berry counting and identifying the berries to be removed has limitations, as the number of visible berries might vary greatly depending on the direction of view. In addition, it is extremely important to understand the 3D structure of a bunch when considering future automation via robotics. For the reasons stated, obtaining a field-applicable 3D grape bunch model is needed. Thus, the contribution of this study is a novel technology for reconstructing a 3D model of a grape bunch with uniquely identified berries from 2D images captured in the real grape field environment.
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  • Publication
    3D nanoporous hybrid nanoflower for enhanced non-faradaic redox-free electrochemical impedimetric biodetermination
    ( 2020-11-01)
    Subramani I.G.
    ;
    Perumal V.
    ;
    Subash Chandra Bose Gopinath
    ;
    Mohamed N.M.
    ;
    Joshi N.
    ;
    Ovinis M.
    ;
    Sze L.L.
    Recently, non-faradaic electrochemical impedimetric (nfEIS) has been identified as a dynamic and robust method for bio-determining. However, the success of a nfEIS approach largely depends on its sensing layer architecture. In this study, the use of a Glutaraldehyde (GA) crosslinked copper (Cu) – bovine serum albumin (BSA) hybrid nanoflower with three-dimensional nanoporous architecture for the sensing layer was investigated. The nanoflower morphology changes were observed under FESEM, revealing loosely interlaced nanoflower into a tightly interlaced, highly porous structure upon GA crosslinking. This nanoflower was hybridized to immobilize aminated-DNA probe on the transducer surface and detect the target TB DNA in their natural redox-free environment. FTIR and XPS characterization showed distinct peaks at 950–1100 cm−1 (P-O, P=O bonds from nanoflower and DNA backbone) and 286.48 eV (interaction between BSA and aminated DNA), respectively, validating the successful DNA probe immobilization on the nanoflower surface. Furthermore, impedimetric sensing in a redox-free environment showed that the developed TB biosensor present has a detection limit (LOD) of 60 pM with a (linear) range from 1 pM to 1 µM with good reproducibility. This redox-free non-faradaic EIS offers excellent biosensing potential and may be extended for diagnosing other biomarkers in clinical practice.
  • 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
    5V to 6kV DC-DC converter using switching regulator with cockcroft- walton voltage multiplier for high voltage power supply module
    ( 2019-01-01)
    Azmi N.
    ;
    Murad S.
    ;
    Harun A.
    ;
    Ismail R.
    Background: This paper describes the design of 5 V to 6 kV DC-DC converter by using a switching regulator with Cockroft-Walton (C-W) voltage multiplier for a high voltage power supply module. Methods: The proposed design consists of Pulse Width Modulation (PWM) controller circuit, voltage multiplier, and feedback signal. A single unit of 5 V input triggers LT1618 controller circuit to generate 20 V which then produces 300 V from LT8331 output that is connected to diode-capacitor multiplier circuit to achieve final 6 kV. A negative feedback signal is required to stabilize an output voltage. With the implementation of C-W voltage multiplier technique, the output is boosted up as required from the input signal voltage 5 V DC. Results: The LTspice simulation results indicate that the proposed DC converter can generate 6.20 kV. Line regulation of 17% and the load regulation of 14% are obtained based on the proposed design. Conclusion: The proposed design is suitable for high voltage power supply module.
  • Publication
    802.11p optimization for delay sensitive in non-safety messages in VANETs
    ( 2018-10-01)
    Elias S.J.
    ;
    Warip M.N.M.
    ;
    Elshaikh M.
    ;
    Darus M.Y.
    ;
    Ahmad R.B.
    Vehicle density and high vehicle mobility are variables that measured the performance of Vehicular Ad Hoc Network (VANET) in unpredictable traffic data transmission environment. This paper is focused on non-safety messages transmission mainly for delay in time in test-bed simulation environment. Network optimization is an approach to evaluate the existing congestion control protocols and other network parameters for outlining a newly enhanced congestion control protocols. This paper presents a city and highway traffic data transmission scenarios for optimizing delay sensitivity utilizing the Taguchi method. The avareage data transmission on delay is performance indicator applying OMNeT++ simulation tools. The optimization process could be achieved once the best fit performance parameters are being identified. The best fit performance values could conclude the optimal and efficient congestion control networks. The packet sizes are the main control factors for this test-bed experiment focusing on non-safety messages which are delay sensitive.
  • Publication
    A 12 GHz LC-VCO Implemented with S’ shape Inductor using Silicon-on Sapphire Substrate
    ( 2022-12-01)
    Khalid N.
    ;
    Nur Anira Asyikin Hashim
    ;
    Nurul Izza Mohd Nor
    ;
    Shahrir Rizal Kasjoo
    ;
    Zaliman Sauli
    ;
    Mohd Norhafiz Hashim
    ;
    Mispan M.S.
    A voltage-controlled oscillator (VCO) is an electronic oscillator whose oscillation frequency is controlled by a voltage input. In a VCO, low-phase noise while consuming less power is preferred. The tuning gain and noise in the control signal produce phase noise; more noise or tuning gain implies more phase noise. Sources of flicker noise (1/f noise) in the circuit, the output power level, and the loaded Q factor of the resonator are all crucial factors that influence phase noise. As a result, creating a resonator with a high Q-factor is essential for improving VCO performance. As a result, this paper describes a 12 GHz LC Voltage-Controlled Oscillator (VCO) employed with a ‘S’ shape inductor to improve phase noise and power performance. The phase noise for the VCO was reduced using a noise filtering technique. To reduce substrate loss and improve the Q factor, the inductor was designed on a high-resistivity Silicon-on-Sapphire (SOS) substrate. At 12 GHz, the optimised S’ shape inductor has the highest Q-factor of 50.217. At 10 MHz and 100 MHz, the phase noise of the 12 GHz LC-VCO was-131.33 dBc/Hz and-156.71 dBc/Hz, respectively. With a 3.3 V power supply, the VCO core consumes 26.96 mW of power. Based on the findings, it is concluded that using an ‘S’ shape inductor in the VCO circuit will enable the development of low-cost, high-performance, very low-power system-on-chip wireless transceivers with longer battery life.
      3
  • Publication
    A 28 GHz high efficiency fully integrated 0.18 µm combined CMOS power amplifier using power divider technique for 5G millimeter-wave applications
    ( 2020-04-01)
    Hasan A.F.
    ;
    Sohiful Anuar Zainol Murad
    ;
    Faizah Abu Bakar
    ;
    Zulkifli T.Z.A.
    A 28 GHz power amplifier (PA) using CMOS 0.18 µm Silterra process technology for milimeter wave applications is reported. Maximizing the power added efficiency (PAE) and output power are achieved by optimize the circuit with power divider and cascade configuration. In addition, reverse body bias is also employed for realizing excellent PAE and power consumption. A three stage CMOS PA with power combiner is designed and simulated. The simulation results show that the proposed PA consumes 62.56 mW and power gain (S21) of 8.08 dB is achieved at 28 GHz. The PA achieves saturated power (Psat) of 12.62 dBm and maximum PAE of 23.74% with output 1-dB compression point (OP1dB) 10.85 dBm. These results demonstrate the proposed power amplifier architecture is suitable for 5G applications.
      1
  • Publication
    A 46% PAE, 2.4-GHz Two-Stage Class E Power Amplifier Utilizing CMOS 0.13-µm Technology
    ( 2024-01-01)
    Sohiful Anuar Zainol Murad
    ;
    Ahmad Fariz Hasan
    ;
    Shaiful Nizam Mohyar
    A wireless device with a long battery life and great sensitivity becomes difficult to develop since there is a huge demand for low-power, low-cost wireless gadgets. The power amplifier (PA) is the most crucial part of radio frequency (RF) transceivers because of its massive power consumption. Consequently, in order to minimize power loss, a very effective and low-power consumption PA is needed. In this paper, high efficiency two-stage CMOS PA designed in 0.13-μm process for 2.4 GHz IoT transmitter applications is presented. The driver stage and power stage are the two stages that make up the two-stage topology of the proposed CMOS PA. To attain high efficiency and great power gain, a class E PA is used at the power stage. The LC matching network at the output is used for harmonic rejection filter at 2.4 GHz with an additional parallel capacitor helps for better harmonic rejection. In addition, a layout has been successfully designed and optimized. All the components in the proposed PA are designed on-chip. The pre-layout and post-layout simulations have been conducted to verify the proposed PA's performance. The pre-layout simulation of the proposed PA can deliver 19.19 dBm output power and 45.2% PAE at 2.0 V power supply into a 50-Ω load. On the other hand, the proposed PA produced an output power of 17.33 dBm and 46% PAE, according to the results of the post-layout simulation with a similar power supply of 2.0 V. The chip area for the proposed layout design is 1.05 mm2.
      1
  • Publication
    A Bidirectional Two-Switch Flyback Converter with Cross-Coupled LCD Snubbers for Minimizing Circulating Current
    ( 2019-08-01)
    Mukhtar N.M.
    ;
    Lu D.D.C.
    This paper proposes a novel isolated bidirectional two-switch flyback converter with two integrated non-dissipative inductor-capacitor-diode (LCD) snubbers. In the proposed topology, the main flyback transformer and the LCD snubbers are cross coupled to minimize circulating current that would occur in the non-cross-coupled case, in addition to recycle leakage energy and protect the power transistors. The same current circulation issue also occurs in the bidirectional flyback converter with conventional resistor-capacitor-diode (RCD) snubbers. The main objective of this paper is to illustrate this issue and propose an alternate circuitry to reduce the current circulation and improve the conversion efficiency. The experimental results of a laboratory prototype are reported to verify the design.
  • Publication
    A Brief Review of Partial Discharge (PD) Detection, Recognition and Location Techniques for Liquid and Gas Insulated High Voltage Equipment
    ( 2019-01-01)
    Bohari Z.H.
    ;
    Isa M.
    ;
    Abdullah A.Z.
    ;
    Rahman A.A.
    High voltage (HV) equipment condition monitoring has become compulsory in the power utility supplier activity since the discovery of multiple failures on HV equipment during operation. The total cost of replacement and installation of HV equipment will cost millions of dollars and the loss of revenue of no supply period during the breakdown. Insulation parts in the HV equipment are the most important component that closely related to the reliability of the electrical system. The insulation part can be solid, liquid, or gaseous form eventually degraded due to existing stresses (electrical, chemical, and mechanical) in the equipment. One common phenomenon called Partial Discharge (PD) associated with HV equipment insulation degradation highlighted in this manuscript, and these situations intensively researched over the century. In this review paper, there are few conventional detections, recent detections, recognition techniques, and location techniques are discussed to explore the available methods to analyze further on the area for the future researcher. The objective of this review to present the latest PD associated techniques and facilitate and convey new information for a future research project.
  • 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.
  • Publication
    A cause of communication failure in managing Industrialized Building System (IBS) projects: A perspective view from project managers
    ( 2018-01-01)
    Pozin M.A.A.
    ;
    Nawi M.N.M.
    ;
    Lee A.
    ;
    Yaakob M.
    ;
    Hanafi M.H.
    An effective communication process is an important element in distributing information to various project teams. The previous study demonstrates the importance of communication in the project management process in order to encourage project delivery processes successfully. Unfortunately, the issue of communication still dominates Industrialization Building System (IBS) because the project development process are still based on traditional methods. This research aims to explore the cause of communication challenges between construction players in managing IBS projects. The research methodology implemented for this paper was a semi-structured interview approach used to investigate the communication problem. Five experienced project managers were chosen from across the industry. The findings of this study are valuable for improving the communication level of project teams, which will indirectly increase the level of the IBS project delivery process and strengthen team integration on IBS projects in Malaysia.
  • Publication
    A compact dual-band rectenna for ambient RF energy harvesting
    ( 2018-11-01)
    Adam I.
    ;
    M. Yasin M.N.
    ;
    A. Rahim H.
    ;
    Soh P.J.
    ;
    Abdulmalek M.F.
    A compact broadband ambient RF energy harvester operating from 1800 MHz up to 2.5 GHz is proposed in this paper. This work is motivated by the huge amount of free and continuously available RF energy in the surroundings that can be utilized into useable energy. Harvest performance is investigated using two antennas in this work, a circular polarized and an array antenna. Due to low ambient power densities, a multistage rectifier is utilized to improve the output dc voltage of the proposed system. Measurements indicate the system is capable of harvesting up to 1.8 Vdc output from nondedicated ambient RF energy sources in an urban area, which is significant in the absence of other energy sources.
  • Publication
    A compact high-gain parasitic patch antenna with electronic beam-switching
    ( 2019-02-01)
    Subramaniam D.
    ;
    Jusoh M.
    ;
    Sabapathy T.
    ;
    Osman M.N.
    ;
    Kamarudin M.R.
    ;
    Othman R.R.
    ;
    Awal M.R.
    A high beam steering antenna using HPND PIN Diode is proposed with a capability of steering its beam into three different directions-40 º, 0º and 40 º with respective switching condition. The reconfigurable parasitic antenna consists of a driven element and two reconfigurable parasitic elements, is designed with operating range of 9.5GHz. The parasitic elements act as reflectors or director depending on the switching conditions. Both parasitic elements are connected to ground plane via shorting pins. The reconfiguration is controlled by the two HPND PIN Diode switch that embeds to the parasitic element. An average gain value of 8dBi is achieved at all reconfiguration scenarios. All the simulated design has been carried out using CST software.
  • Publication
    A comparative study for different sizing of solar PV system under net energy metering scheme at university buildings
    ( 2018-09-01)
    Mansur T.
    ;
    Baharudin N.
    ;
    Ali R.
    Malaysia has moved forward by promoting the use of renewable energy such as solar PV to the public to reduce dependency on fossil fuel-based energy resources. Due to the concern on high electricity bill, Universiti Malaysia Perlis (UniMAP) is keen to install solar PV system as an initiative for energy saving program to its buildings. The objective of this paper is to technically and economically evaluate the different sizing of solar PV system for university buildings under the Net Energy Metering (NEM) scheme. The study involves gathering of solar energy resource information, daily load profile of the buildings, sizing PV array together with grid-connected inverters and the simulation of the designed system using PVsyst software. Based on the results obtained, the amount of solar energy generated and used by the load per year is between 5.10% and 20.20% from the total annual load demand. Almost all solar energy generated from the system will be self-consumed by the loads. In terms of profit gained, the university could reduce its electricity bill approximately between a quarter to one million ringgit per annum depending on the sizing capacity. Beneficially, the university could contribute to the environmental conservation by avoiding up to 2,000 tons of CO2 emission per year.
  • Publication
  • Publication
    A comparative study of different blood vessel detection on retinal images
    ( 2019-01-01)
    Mustafa W.A.
    ;
    Mahmud A.S.
    ;
    Aihsan M.Z.
    ;
    Saifizi M.
    ;
    Charin C.
    Detection of blood vessel plays an important stage in different medical areas, such as ophthalmology, oncology, neurosurgery, and laryngology. The significance of the vessel analysis was helped by the continuous overview in clinical studies of new medical technologies intended for improving the visualization of vessels. In this paper, several local segmentation techniques which include such as Vascular Tree Extraction, Tyler L. Coye and Line tracking, Kirsch's Template and Fuzzy C Mean methods were studied. The main objective is to determine the best approaches in order to detect the blood vessel on the degraded retinal input image (DRIVE dataset). A few Image Quality Assessment (IQA) was obtained to prove the effectiveness of each detection methods. Overall, the result of sensitivity highest came from Kirsch Templates (96.928), while specificity from Fuzzy C means (77.573). However, in term of accuracy average, the Line Tracking method is more successful compared to the other methods.