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PublicationEffect of sintering mechanism towards crystallization of geopolymer ceramic - a review(MDPI, 2023)Globally, there is an increasing need for ceramic materials that have a variety of applications in the environment, for precision tools, and for the biomedical, electronics, and environmental industries. However, in order to obtain remarkable mechanical qualities, ceramics have to be manufactured at a high temperature of up to 1600 °C over a long heating period. Furthermore, the conventional approach presents issues with agglomeration, irregular grain growth, and furnace pollution. Many researchers have developed an interest in using geopolymer to produce ceramic materials, focusing on improving the performances of geopolymer ceramics. In addition to helping to lower the sintering temperature, it also improves the strength and other properties of the ceramics. Geopolymer is a product of polymerization involving aluminosilicate sources such as fly ash, metakaolin, kaolin, and slag through activation using an alkaline solution. The sources of the raw materials, the ratio of the alkaline solution, the sintering time, the calcining temperature, the mixing time, and the curing time may have significant impacts on the qualities. Therefore, this review aims to study the effects of sintering mechanisms on the crystallization of geopolymer ceramics, concerning the strength achieved. A future research opportunity is also presented in this review.
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PublicationNumerical analysis on the anode active thickness using quasi-three-dimensional solid oxide fuel cell model(Elsevier, 2023)A quasi-three-dimensional solid oxide fuel cell (SOFC) model reduces the computational cost by strategically ignoring the thinnest direction in an SOFC by incorporating a charge-transfer current density model to represent its active thickness in electrodes to represent its complex phenomenon in an electrode. Therefore, high accuracy of this charge-transfer current density model is required. The concentration loss is mathematically related to the charge-transfer current density based on the dusty-gas model together with activation and ohmic losses in this work. The numerical results from this study are validated with the experimental results. The influence of anode's thickness towards anode active thickness is studied with the anode thickness of 5, 10, 50, 100, 500 and 1000 μm. It is found that the quasi-three-dimensional SOFC model is capable of analysing SOFC with a sufficiently thick electrode. Also, a thick electrode and a high average current density result in a thin active thickness.
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PublicationDeep CNN-based Planthopper classification using a high-density image dataset(MDPI, 2023)Rice serves as the primary food source for nearly half of the global population, with Asia accounting for approximately 90% of rice production worldwide. However, rice farming faces significant losses due to pest attacks. To prevent pest infestations, it is crucial to apply appropriate pesticides specific to the type of pest in the field. Traditionally, pest identification and counting have been performed manually using sticky light traps, but this process is time-consuming. In this study, a machine vision system was developed using a dataset of 7328 high-density images (1229 pixels per centimetre) of planthoppers collected in the field using sticky light traps. The dataset included four planthopper classes: brown planthopper (BPH), green leafhopper (GLH), white-backed planthopper (WBPH), and zigzag leafhopper (ZIGZAG). Five deep CNN models—ResNet-50, ResNet-101, ResNet-152, VGG-16, and VGG-19—were applied and tuned to classify the planthopper species. The experimental results indicated that the ResNet-50 model performed the best overall, achieving average values of 97.28% for accuracy, 92.05% for precision, 94.47% for recall, and 93.07% for the F1-score. In conclusion, this study successfully classified planthopper classes with excellent performance by utilising deep CNN architectures on a high-density image dataset. This capability has the potential to serve as a tool for classifying and counting planthopper samples collected using light traps.
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PublicationAn investigation of the processability of natural fibre reinforced polymer composites on shallow and flat thin-walled parts by injection moulding process( 2013)Currently, many industries are trending towards producing products exhibit such properties as small thickness, lightweight, small dimensions, and environmental friendliness. In this project, flat or shallow thin-walled parts were designed to compare the advantages and disadvantages of lignocellulosic polymer composites (PP + 50 wt% wood) in terms of processability. This study focused on the filling, in-cavity residual stresses and warpage parameters associated with both types of thin-walled moulded parts. Thin-walled parts 0.7 mm in thickness were suitably moulded using lignocellulosic composite materials to determine the effects of filling. The analysis showed, the shallow thin-walled part is preferable in moulding lignocellulosic polymer composite material due to the low residual stress and warpage measured. The results also indicate that the shallow thin-walled part is structurally rigid, such that it can be used in applications involving small shell parts, and can be processed more economically using less material than the flat thin-walled part.
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PublicationThe effect of bileaflet mechanical heart valve designs on biomechanical behaviours – a finite element analysis( 2023)Heart valve replacement is a popular treatment modality for patients with valvular heart disease. One of the prominent issues of mechanical heart valve is blood clotting around the valve that could lead to operation failure. Different valve design affects the valve structural behaviour differently which could be associated to the valve leaflet movement and its attachment to the housing. This study aimed to analyse the stress and total deformation of a fixed and expandable heart valve designs under a closed and opened leaflet conditions using three-dimensional (3-D) finite element analysis (FEA). Geometrical valve models were created in SolidWorks 2020 and then exported into Ansys 2022 R2. All models were assigned with linearly elastic, isotropic, and homogenous properties. A pressure of 16 kPa was applied on the top (closed condition) and bottom (opened condition) surfaces of the leaflets. The results exhibited that the expandable design recorded about 98% and 8.6% higher stress than the fixed design under the closed and opened conditions, respectively. The expandable valve was also observed to generate approximately 186% and 182% greater total deformation compared to the fixed valve under the closed and opened conditions, respectively. Of the valve designs evaluated, the fixed valve was found to be more satisfactory. However, the expandable valve could also be of interest with relevant modifications imposed if the adverse functionality impacts are concerned.