Azizi Harun
Thumbnail Image
Preferred name
Azizi Harun
Official Name
Azizi, Harun
Alternative Name
Harun, Azizi
Harun, A.
Bin Harun, Azizi
Main Affiliation
Scopus Author ID
15063856600
Researcher ID
V-6892-2019

Research Output

Filters

27
Reset filters

Settings
Now showing 1 - 10 of 27
  • Publication
    Signal propagation analysis for low data rate wireless sensor network applications in sport grounds and on roads
    ( 2012)
    David L. Ndzi
    ;
    M. A. Mohd Arif
    ;
    Ali Yeon Md Shakaff
    ;
    Mohd Noor Ahmad
    ;
    Azizi Harun
    ;
    Latifah Munirah Kamarudin
    ;
    Ammar Zakaria
    ;
    Mohd F. Ramli
    ;
    Mohammad Shahrazel Razalli
    This paper presents results of a study to characterise wire- less point-to-point channel for wireless sensor networks applications in sport hard court arenas, grass fields and on roads. Antenna height and orientation effects on coverage are also studied and results show that for omni-directional patch antenna, node range is reduced by a factor of 2 when the antenna orientation is changed from vertical to horizontal. The maximum range for a wireless node on a hard court sport arena has been determined to be 70m for 0dBm transmission but this reduces to 60m on a road surface and to 50m on a grass field. For horizontal antenna orientation the range on the road is longer than on the sport court which shows that scattered signal components from the rougher road surface combine to extend the communication range. The channels investigated showed that packet error ratio (PER) is dominated by large-scale, rather than small-scale, channel fading with an abrupt transition from low PER to 100% PER. Results also show that large-scale received signal power can be modeled with a 2nd or der log-distance polynomial equation on the sport court and road, but a 1st order model is sufficient for the grassfield. Small-scale signal variations have been found to have a Rice distribution for signal to noise ratio levels greater than 10 dB but the Rice K-factor exhibits significant variations at short distances which can be attributed to the influence of strong ground reflections.
  • Publication
    Design of 5 V DC to 20 V DC switching regulator for power supply module
    ( 2017)
    Nor Afiqah Azmi
    ;
    Sohiful Anuar Zainol Murad
    ;
    Azizi Harun
    ;
    Rizalafande Che Ismail
    ;
    Mohd Nazrin Md Isa
    ;
    M. A. Zulkifeli
    This paper presents the design of 5 V to 20 V DC switching regulator for power supply module. A voltage multiplier which consists of cascaded diode-capacitor combination is used in order to obtain a high voltage power supply. Due to power loss that has occurred in a stray of component arrangement, the proposed design employs a pulse width modulation (PWM) controller circuit with an inclusion of a capacitor, diode, and inductor components. The input supply of 5 V DC to LT1618 controller circuit has produced 20.35 V based from simulation results. Meanwhile, the measurement results of 19.36 V are obtained and the feedback signal is required for the purpose of stabilizing the output. The proposed design can reduce the components as well as the PCB size, thus minimizing the overall cost of making a switching regulator for power supply module. © 2017 Author(s).
  • Publication
    Signal propagation modelling for vehicle-to-infrastructure communication under the influence of metal obstruction
    ( 2021-12)
    Jamie Siregar Cynthia Turner
    ;
    Shahriman Abu Bakar
    ;
    Azizi Harun
    ;
    Mohd Sani Mohamad Hashim
    ;
    Zuradzman Mohamad Razlan
    ;
    D L Ndzi
    ;
    Rizalafande Che Ismail
    ;
    Sohiful Anuar Zainol Murad
    ;
    Mohd Nazrin Md Isa
    ;
    Shaiful Nizam Mohyar
    ;
    Mohammad Fadzli Ramli
    ;
    M K N Zulkifli
    Connected car has become one of emerging technology in the automotive industries today. This development preludes a rise in vehicular communication studies that primarily targets radio channel modelling on vehicle-to-vehicle (V2V) and vehicle-to-infrastructure (V2I) communication mode. Considering vehicular obstruction, vast channel propagation studies have focused more on V2V mode while others consider the typical urban scenarios consisting of high traffic volumes of moving vehicles. Due to challenging propagation mechanisms and high complexity in such areas, radio propagation models applied in simulators assume an obstacle-free environment rather than considering the least effect imposed by metal obstruction on communication signal. Besides, there are limited studies pertaining to metal obstruction that considers several under-explored environments such as actual parking lots, junctions and other road infrastructure support. As such, this paper demonstrates signal attenuation analysis caused by the presence of metal objects in low density over obstacle-free environment on actual parking lot via V2I mode. Two scenarios such as LOS and NLOS conditions consisting of obstacle-free, cars and buses as static metal objects are evaluated. The aim of this research is to characterize signal strength caused by metal blockage on radio wave propagation predicated on the presence of vehicles as a subject of obstruction in comparison to obstacle-free vehicular environment. The validity of data is shown through received signal strength indicator (RSSI) and approximation analysis (RMSE) to demonstrate the efficiency of obtained measurements. The results demonstrated that Log-normal shadowing model yields the best fit to low-density metal obstruction scenario with smallest RMSE of 4.78 under bus obstruction whereas 5.72 under car obstruction.
  • Publication
    Electrical conductivity (EC) sensing system for paddy plant using the internet of things (IoT) connectivity
    ( 2020-01-08)
    Othaman N.N.C.
    ;
    Mohd Nazrin Md Isa
    ;
    Sohiful Anuar Zainol Murad
    ;
    Azizi Harun
    ;
    Shaiful Nizam Mohyar
    This paper presents the design and development of an IoT-based electrical conductivity system for measuring paddy soil nutrients. Relationship between electrical conductivity (EC) and the influence of soil temperature in precision farming will be discussed. In this work, the EC algorithm was modelled and verified using MATLAB and realized on Node MCU (ESP8266) microcontroller. Results showed that the measured data from the developed system is closed to the calibration solution conductivity that is 1.413mS/cm and 12.88mS/cm. It is also noted that the recorded electrical conductivity value increases with temperature.
  • Publication
    Engine performance enhancement by improving heat transfer in between exhaust valve and valve seat through CFD (transient thermal) simulation
    ( 2021-05-03)
    Mohamad Aniq Syazwan Mohamed Hassan
    ;
    Shahriman Abu Bakar
    ;
    Zuradzman Mohamad Razlan
    ;
    Nur Saifullah Kamarrudin
    ;
    Aziz I.A.
    ;
    Wan Khairunizam Wan Ahmad
    ;
    Mohd Sani Mohamad Hashim
    ;
    Azizi Harun
    ;
    Ishak Ibrahim
    ;
    Ibrahim Z.
    ;
    Mohd Khairul Faizi Abd Rahman
    ;
    Muhammad Faiz Hilmi Rani
    ;
    Rishan Murali
    The combustion of the internal combustion engine results in high heat and pressure produce as exhaust gas. The high-temperature exhaust gas will transfer the heat to surrounding via convection, conduction, and radiation. In the combustion chamber, the exhaust valve and its seat will reach high temperatures due to hot gases exit through the engine exhaust port. This high temperature must be reduced to avoid damaging the engine. In this project, the existing material of the valve seat is tested using computational fluid dynamics simulation for heat analysis. Simulation of transient thermal is conducted to study the detailed behavior of heat transfer of the valve and valve seat in the engine. Four copper-based material of the valve seat is selected which is beryllium copper, chromium copper, brass, bronze are simulated. In the simulation, the brass valve seat has the highest heat absorbance rate which averagely 30% higher than cast iron valve seat in terms of temperature differences. Most of the copper-based valve seat can absorb averagely 10% to 30% more heat than cast iron valve seat depends on the material's thermal conductivity.
      3  17
  • Publication
    Engine Performance Analysis by Studying Heat Transfer in the Valve Seat through Steady-State Thermal Simulation
    ( 2021-12-14)
    Mohamad Aniq Syazwan Mohamed Hassan
    ;
    Shahriman Abu Bakar
    ;
    Zuradzman Mohamad Razlan
    ;
    Nur Saifullah Kamarrudin
    ;
    Wan Khairunizam Wan Ahmad
    ;
    Mohd Sani Mohamad Hashim
    ;
    Azizi Harun
    ;
    Ishak Ibrahim
    ;
    Azizul Aziz I.
    ;
    Zunaidi Ibrahim
    ;
    Mohd Khairul Faizi Abd Rahman
    ;
    Muhammad Faiz Hilmi Rani
    ;
    Anas Abdul Rahman
    ;
    Mohd Afendi Rojan
    ;
    Rishan Murali
    As the engine reached high speed, the exhaust valve temperature increased exponentially due to the exhaust gas produced by the combustion process between the mixture of air and fuel within the combustion chamber of the internal combustion engine. The valve is subjected to thermal loading due to high temperature and pressure within the cylinder, which must withstand a material temperature for sustainable and optimal operation. To avoid this loss, a perfect medium must be prepared to ensure that the heat is extracted smoothly. This can be done when the valve is in contact with the seat and there is a periodic heat transfer contact. Therefore, it is imperative to research the correlation between valve and valve seat to understand the two sections' heat transfer mechanism. In this study, thermal contact analysis was used to identify heat transfer between the valve and the valve seat as both parts are interconnected. This research also has an interest in studying the two surface conduction mechanisms as the exhaust valve closed in steady-state conditions. Thus, this study portrays a significant method, particularly for the determining the distribution of temperature, heat flux, and heat flux direction between the valve and its seat using ANSYS Workbench.
      2
  • Publication
    Speed and Area Efficient FXP Adders and Multipliers: A Comparative Analysis for LNS System
    ( 2020-12-18)
    Basir M.S.S.M.
    ;
    Rizalafande Che Ismail
    ;
    Siti Zarina Md Naziri
    ;
    Mohd Nazrin Md Isa
    ;
    Sohiful Anuar Zainol Murad
    ;
    Azizi Harun
    In this paper, a variety of adder and multiplier are compared to be implemented in a new logarithmic number system (LNS). Both adder and multiplier are designed with a generic very high-speed integrated circuit hardware description language (Verilog) program. This makes it possible to achieve the optimum performance in latency and area of 0.18µm CMOS technologies LNS chip. Consequently, the optimal configurations vary with speed and area of the schemes and in some cases can be compact area, O(n), fast in latency O(log2 n) or optimized. The program was scripted based on fixed-point (FXP) adders and multipliers that yet will be implemented in LNS system. The functionality of the scheme was tested before synthesized. Outcomes show that Ladner Fisher (LF) adder and modified Baugh Wooley multiplier contribute to fast in latency and consume minimal area.
      4  11
  • Publication
    A very low-dropout voltage regulator in 0.18-μm CMOS technology for power management system
    ( 2020-07-01)
    Sohiful Anuar Zainol Murad
    ;
    Azizi Harun
    ;
    Mohd Nazrin Md Isa
    ;
    Shaiful Nizam Mohyar
    ;
    Karim J.
    A low dropout (LDO) voltage regulator is a type of voltage regulator circuit that works well even when the output voltage is very close to the input voltage, improving its power efficiency. This paper proposes the LDO voltage regulator in 0.18-μm CMOS technology. The proposed LDO regulator consists of voltage reference, symmetrical operational transconductance amplifier (OTA), PMOS transistor, resistive feedback network and output capacitor. The NMOS symmetrical OTA is implemented as an error amplifier and a PMOS transistor is employed as a pass device to improve gain and minimize low dropout voltage, respectively. The proposed design is simulated using Spectre simulator in Cadence software to verify its regulator performance. The simulation results show that the proposed LDO is capable to operate from a supply voltage of 1.7-2.0 V with a low dropout voltage of 19.3 mV at a maximum 50 mA load current to regulate output voltage 1.5 V. The active chip is 2.96 mm2 in size. The performance of the proposed LDO is suitable to enhance power management for system on chip (SoC) applications.
      1  10
  • Publication
    Modelling on Impact of Building Obstruction for V2I Communication Link in Micro Cellular Environment
    ( 2021-03-01)
    Turner J.S.C.
    ;
    Shahriman Abu Bakar
    ;
    Azizi Harun
    ;
    Sohiful Anuar Zainol Murad
    ;
    Isa M.N.
    ;
    Ismail R.C.
    ;
    Ndzi D.L.
    ;
    Hashim M.S.M.
    ;
    Zuradzman Mohamad Razlan
    ;
    Wan Khairunizam Wan Ahmad
    ;
    Ramli M.F.
    In vehicular communication, signal transmission in vehicle-to-infrastructure (V2I) mode typically takes place on highways, urban, suburban and rural environments. The presence of buildings in these environments poses a challenge to model path loss (PL) due to multiple propagation mechanisms such as diffractions and reflections. However, very little attention has been made to address building effects on the performance of V2I communication links in microcell environment. This paper investigates signal propagation characteristics caused by the impact of building under micro-cellular environment whereby the base station or road-side-unit (RSU) is usually located under the rooftop of building to allow communication between RSU and mobile station or on-board-unit (OBU) on the road. The goal of this paper is to validate and discuss available path loss models based on effect of building obstruction towards RSU-OBU links specifically in residential housing area. The channel measurements are conducted based on static line-of-sight (LOS) settings of a real-world environment at 2.4 GHz frequency band using IEEE 802.15.4 XBee S2C compliant device to measure its receive power. The results are demonstrated based on received signal strength indicator (RSSI) and root mean square error (RMSE). The attenuation profile is validated and compared with suitable path loss models to evaluate best fit and most compatible model based on our measurements data and environment. The analysis shows that several V2I path loss models and V2V channel models are applicable to be used as a reference to model in LOS microcell environment with building obstruction. The finding shows that PL Urban yields the best fit V2I path loss model in terms of RMSE when compared to our measurement campaign at 2.4 GHz.
      2
  • Publication
    Hybrid Floating Point/Logarithmic Number System Processor
    ( 2020-12-18)
    Sheng C.Y.
    ;
    Rizalafande Che Ismail
    ;
    Siti Zarina Md Naziri
    ;
    Mohd Nazrin Md Isa
    ;
    Sohiful Anuar Zainol Murad
    ;
    Azizi Harun
    Hybrid Floating Point/Logarithmic Number System processor is an Arithmetic Logic Unit with hybrid architecture in which its data computation involves Floating Point (FLP) and Logarithmic Number System (LNS). LNS processor has high performance but requires complicated hardware to support its function, especially LNS addition and subtraction. Therefore, hybrid processor is proposed to perform multiplication/division in LNS, addition/subtraction in FLP. Through merging FLP and LNS, data computation can be done in a faster, precise and less complicated way. The proposed research is a 32-bit Hybrid FLP/LNS processor, which involving 32-bit fixed point data format and 32-bit single precision FLP format. The EDA tools used in developing and simulating this project is based on Synopsys Design Compiler and Altera Quartus II, and the Hardware Description Language used is Verilog HDL. Logical synthesis of this project is done by using Synopsys Design Compiler and its area, timing and power are validated.
      3  6