Wan Khairunizam Wan Ahmad
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Preferred name
Wan Khairunizam Wan Ahmad
Official Name
Wan Khairunizam, Wan Ahmad
Alternative Name
Wan, Khairunizam
Ahmad, Wan Khairunizam Wan
Khairunizam, W. A. N.
Main Affiliation
Scopus Author ID
57200576499
Researcher ID
E-6072-2011

Research Output

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  • Publication
    A study of non-gaussian properties in emotional eeg in stroke using higher-order statistics
    ( 2020-01-01)
    Yean C.W.
    ;
    Murugappan M.
    ;
    Omar M.I.
    ;
    Wan Khairunizam Wan Ahmad
    ;
    Zheng B.S.
    ;
    Raj A.N.J.
    ;
    Ibrahim Z.
    The stroke patients often suffered from emotional disturbances, and this leads to perceive emotions differently than normal control subjects; the emotional impairment of the stroke patients can be effectively analyzed using EEG signal. The EEG signal has been known to have non-Gaussian properties, and the non-Gaussianity characteristics of the EEG differ under different emotional states. The analysis of non-Gaussianity in EEG signal was performed by using higher-order statistics measures such as the skewness and kurtosis. In this study, the non-Gaussianity was examined in the emotional EEG signal of stroke patients and normal control subjects. The estimation of the emotional EEG distribution from the results was symmetrically non-Gaussian for both stroke and normal groups. Particularly, it was found that the normal subjects have more non-Gaussian EEG distribution than the stroke patients.
      1  19
  • Publication
    An Experimental Framework for Assessing Emotions of Stroke Patients using Electroencephalogram (EEG)
    ( 2020-06-17)
    Wan Khairunizam Wan Ahmad
    ;
    Yean C.W.
    ;
    Murugappan M.
    ;
    Ahmad Kadri Junoh
    ;
    Zuradzman Mohamad Razlan
    ;
    Wan Azani Wan Mustafa
    ;
    Shahriman Abu Bakar
    ;
    Ibrahim Z.
    ;
    Nurhafizah S.
    This research aims to assess the emotional experiences of stroke patients using Electroencephalogram (EEG) signals. Since emotion and health are interrelated, thus it is important to analyse the emotional states of stroke patients for neurofeedback treatment. Moreover, the conventional methods for emotional assessment in stroke patients are based on observational approaches where the results can be fraud easily. The observational-based approaches are conducted by filling up the international standard questionnaires or face to face interview for symptom recognition from psychological reactions of patients and do not involve experimental study. This paper introduces an experimental framework for assessing emotions of the stroke patient. The experimental protocol is designed to induce six emotional states of the stroke patient in the form of video-audio clips. In the experiments, EEG data are collected from 3 groups of subjects, namely the stroke patients with left brain damage (LBD), the stroke patients with right brain damage (RBD), and the normal control (NC). The EEG signals exhibit nonlinear properties, hence the non-linear methods such as the Higher Order Spectra (HOS) could give more information on EEG in the signal's analysis. Furthermore, the EEG classification works with a large amount of complex data, a simple mathematical concept is almost impossible to classify the EEG signal. From the investigation, the proposed experimental framework able to induce the emotions of stroke patient and could be acquired through EEG.
      1  17
  • Publication
    Derivation and validation of heat transfer model for Spark-Ignition engine cylinder head
    ( 2023-05-05)
    Hassan M.A.S.M.
    ;
    Zuradzman Mohamad Razlan
    ;
    Shahriman Abu Bakar
    ;
    Anas Abdul Rahman
    ;
    Mohd Afendi Rojan
    ;
    Wan Khairunizam Wan Ahmad
    ;
    Ibrahim Z.
    ;
    Ishak A.A.
    ;
    Mohd Ridzuan Mohd Jamir
    The valve train is located in the engine cylinder head, which has various operational heat transfer mechanisms to accommodate the combustion process. Most heat transfer studies in this area have only addressed medium-to high-power vehicles at a single running speed. In this study, a model of an air-cooled underbone motorcycle valve, valve seat, and engine cylinder head was tested to determine the thermal characteristics using actual engine operating conditions at low, medium, and high engine speeds. One-dimensional thermal simulation analyses were conducted to obtain the instantaneous heat-transfer coefficients of an actual engine. The average thermal value was determined as the boundary condition in the three-dimensional thermal analysis. A three-dimensional model was prepared using the ANSYS commercial computational fluid dynamics software package. The results show that as the engine speed increases, so does the thermal load toward the component in the engine cylinder head. The strongest temperature regions were concentrated around the combustion face. The exhaust valve held most of the heat, with the valve neck recording the highest temperature. For the intake valve, the combustion face registered the majority of the heat. The heat flux intensity was gathered in the contact surface area between the valve and its seat, between the valve stem and guide, and between the stem guide and tip section. A thermal survey was used to validate the three modelling results for two separate engine datasets. The cumulative relative errors for intake and exhaust valve seats for low engine speeds were 3.73% and 0.17%, respectively. The intake and exhaust valve seats had cumulative relative errors of 4.12% and 0.70%, respectively, at intermediate speeds. This methodology provides valuable information for analysing the heat characterisation of air-cooled engines. It can also be a useful blueprint for the automotive industry and other researchers involved in thermal measurements.
      32  2
  • Publication
    Temperature Distribution Analysis of Lithium-Ion Polymer Battery Surface
    ( 2022-01-01)
    Murali Rishan
    ;
    Zuradzman Mohamad Razlan
    ;
    Shahriman Abu Bakar
    ;
    Suffer K.H.
    ;
    Ibrahim Z.
    ;
    Wan Khairunizam Wan Ahmad
    ;
    Mohd Rudzuan Mohd Nor
    ;
    Muhammad Faisal Hamidi @ Abdul Rani
    The main objective of this study is to investigate the heat load generated by the Lithium-ion (Li-ion) battery during the completion of the cycle. Besides that, the objective is also to identify the most affected surface of the Li-ion battery towards the temperature during the charging and discharging process. An experiment is carried out for five different conditions of battery to obtain the data for heat load calculation purposes. The five conditions are differences in discharge ampere. From the result obtained there are differences in heat load generated by the battery during the charging and discharging process for every condition. Furthermore, the greater the discharge ampere, the lower the time taken for the battery to discharge and the higher the heat load generated by the battery. Besides that, an experiment to investigate the temperature distribution along the experiment is also carried out. Four surfaces of battery (front, right, left, back in vertical position of battery) are put into concern in obtaining the temperature distribution. Every surface gives a different temperature distribution during the experiment. Surface 4 recorded the highest average temperature distribution. Thus, the cooling system will consider the cooling capacity at this surface.
      1  57
  • Publication
    Design Optimization of Exhaust Manifold's Divergence Characteristics in Enhancing High-End Power in 115cc SI Engine
    ( 2022-01-01)
    Murali R.
    ;
    Shahriman Abu Bakar
    ;
    Zuradzman Mohamad Razlan
    ;
    Ishak A.A.
    ;
    Ika Syahira Abdullah
    ;
    Mohd Afendi Rojan
    ;
    Ibrahim Z.
    ;
    Wan Khairunizam Wan Ahmad
    The exhaust system especially the exhaust manifold is an essential component that affects the performance of the Spark Ignition (SI) engine. The critical factor inside the exhaust system that affects the engine's performance is backpressure. Backpressure is known as the difference between maximum pressure in the exhaust system and atmospheric pressure. Based on previous studies, it was found that an un-optimal exhaust manifold's design leads to higher backpressure that reduces the performance and the fuel efficiency of the SI engine. This research aimed at enhancing the high-end power of the 115cc SI engine by optimizing the exhaust manifold's divergence characteristics through 1D engine analysis. S/N ratio analysis was used through Taguchi's method as a tool to conduct the design optimization. From the analysis, it was found that the optimal exhaust manifold's divergence configuration improved the mean brake power by 4.67% at high-end engine speed. It is expected that the optimal exhaust manifold's divergence configuration could also improve the engine's brake torque and fuel efficiency which could directly reduce the carbon footprint to the environment.
      1  30
  • Publication
    Approach to enhance the heat transfer of valve seats through thermal analysis
    ( 2022-02-05)
    Hassan M.A.S.M.
    ;
    Zuradzman Mohamad Razlan
    ;
    Shahriman Abu Bakar
    ;
    Mohd Afendi Rojan
    ;
    Wan Khairunizam Wan Ahmad
    ;
    Ibrahim Z.
    ;
    Ishak A.A.
    ;
    Rahman A.A.
    ;
    Mohd Ridzuan Mohd Jamir
    The valve seat insert is a component of the engine cylinder head, whose primary function is to seal the combustion chamber and absorb the valve's heat, releasing it to the engine cylinder head. The valves experience high temperatures owing to high thermal loading and low heat absorption in the valve seat, which can potentially damage the engine. Therefore, the thermal characteristics of the valve seat must be optimised to increase the heat transmission between the valve and its seat. Here, three copper alloy valve seats, brass, beryllium copper, and bronze copper, were tested against the existing sintered iron valve seat, and their temperature maps were determined using actual engine operation conditions. The instantaneous heat transfer coefficients of the valves, seats, and engine cylinder head during the four-stroke cycle were evaluated using a one-dimensional thermal simulation analysis. The values obtained were used to assess the finite-element model using a three-dimensional thermal simulation in the Ansys software. The results show that the brass, beryllium-, and bronze-copper valve seats increased the overall heat flux by 4.46%, 4.16%, and 2.06%, respectively, compared to those for sintered iron. Thus, the results are essential to improve the thermal characteristics of the copper alloy valve seat imposed on the cylinder head. For validation, an experimental engine thermal survey and uncertainty magnification factors were used to validate the model. The results indicate that the maximum difference between the simulation and experimental values is 8.42%. Therefore, this approach offers a direct and comprehensible application for evaluating the temperature distribution, heat gradient, and heat flux of the cylinder head of air-cooled spark-ignition moped motorcycle engines using copper alloy valve seat materials at intermediate engine speeds. Furthermore, this method is applicable as a platform for the automotive industry to improve the heat transfer of the structural parts of internal combustion engines.
      1  41
  • Publication
    A review on the correlation between exhaust backpressure and the performance of IC engine
    ( 2021-10-25)
    Murali R.
    ;
    Shahriman Abu Bakar
    ;
    Zuradzman Mohamad Razlan
    ;
    Wan Khairunizam Wan Ahmad
    ;
    Azizul A.I.
    ;
    Mohd Afendi Rojan
    ;
    Ma’arof M.I.N.
    ;
    Radzuan M.A.
    ;
    Hassan M.A.S.M.
    ;
    Ibrahim Z.
    The exhaust system in any Internal Combustion (IC) engine is a critical component that affects the engine's performance. A poorly designed exhaust system generally results in an increment of exhaust backpressure. Backpressure is one of the fluid's characteristics that acts as a resistance to exhaust gas flow. Relatively higher backpressure blocks the exhaust gas flow from discharging efficiently, decreasing the engine's performance. In general, higher backpressure results in power and torque loss as well as higher fuel consumption and emission to the environment. This review paper aims to elucidate the relationship between exhaust backpressure and the performance of IC engine. Various past studies were conducted to study the effect of exhaust backpressure on the performance of IC engine through Computational Fluid Dynamic (CFD) simulation, engine simulation and experimental analysis. Some studies used Taguchi's method to optimize the exhaust manifold's design in respect to backpressure decrement. It was found that 0.22 kW to 0.45 kW of engine's power increases for every 1 kPa of exhaust backpressure decrement. At the same time, 1.5% to 3% of fuel consumption decreases for every 10 kPa of backpressure decrement. In contrast, higher backpressure does reduce the Nitrous Oxides (NOx) emission in the exhaust gas due to higher temperature. Therefore, exhaust backpressure must be minimized to improve any IC engine's performance if the NOx emission is neglected. This review paper is expected to provide a better understanding of the impact of exhaust backpressure on IC engine's performance.
      4  18