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- PublicationAnti-diabetic and anti-lethargic effects of stichopus horrens extract in type 2 diabetes-induced sprague dawley male rats(2025-01)Diabetes mellitus is a chronic metabolic disorder, that is attributed to either insufficient insulin production by the pancreas or impaired response of body cells to insulin. Present medication like metformin has brought significant therapeutic effects in treating this disease but the side effects prompt the researchers to explore other alternative treatments especially natural products. This study aimed to investigate the potential of different sea cucumber samples of Stichopus horrens, differentiated by extraction methods, in reducing fasting blood glucose level, minimising fatigue condition, and restoring structure and function in organs of diabetic type 2-induced rats. Two extraction methods were utilised in this study, which are hydrolysis and high-pressure processing (HPP). The first extract of sea cucumber was subjected to hydrolysis only, while the second extract was exposed to HPP only. The last extract of sea cucumber was subjected to both hydrolysis and HPP. In the in-vitro assay, human umbilical vein endothelial cells (HUVECs) were exposed to three Stichopus horrens body wall samples, and a positive control, metformin with concentrations ranging from 6.25 to 4000 µg/mL in MTT assay to obtain starting dosage of treatments for animal study. The in-vivo study involved Sprague Dawley (SD) rats, which included the induction of high fat diet for five weeks, 110 mg/kg of nicotinamide injection, followed by 55 mg/kg of streptozotocin (STZ) into creating Type 2 diabetes mellitus (T2DM) rat model. Rats were randomly grouped into six groups; normal control (n=3), diabetic control (n=3), metformin-treated group (n=3), sea cucumber extract (hydrolysis only) (n=3), sea cucumber extract (HPP only) (n=3), and sea cucumber extract (HPP and hydrolysis) (n=4). The findings displayed a decreasing trend in cell viability with increasing sea cucumber concentration with ICS0 values of 3.771 ± 0.152 µg/mL in sea cucumber extract (hydrolysis only), 3.783 ± 0.063 µg/mL in sea cucumber extract (HPP only), and 4.006 ± 0.054 µg/mL in sea cucumber extract (HPP and hydrolysis) while metformin depicted an increasing trend of cell viability with ECS0 value of 4.931 ± 4.044 µg/mL. As a result, the starting dosage for animal study pertaining to different treatments is 150 mg/kg each. The findings depicted decreasing trend of blood glucose level after four weeks of treatments with 150 mg/kg sea cucumber samples and increased exercise tolerance in sea cucumber extract (HPP and hydrolysis) group with 150 mg/kg. Apart from that, sea cucumbers exhibited mild restoration in histological changes of liver, kidney, and pancreas. The short treatment duration of sea cucumber on diabetic rats might prove that sea cucumber is a promising candidate for the development of novel product in the future.
- PublicationOptimal dispatching and flexible topology methods for urban power systems(2024-01)This thesis aims to investigate the optimal operation of three forms of Urban Power Systems (UPSs) which will be co-existence in a long time. First of all, aiming at AC / DC hybrid distribution system, the thesis proposes a comprehensive optimal dispatching model with centralized two-stage dispatching framework, achieving a 25.9% reduction in power loss compared to the initial model and increasing the integration of renewable distributed generations from 71% to 200%. Secondly, aiming at AC / DC hybrid active distribution system, the thesis incorporates social behaviours of electric vehicles and power demand response within a three-stage energy management framework, leading to a 13.07% enhancement in social welfare and a 19.90% increase in calculation speed. At last, aiming at transmission and distribution coupling system, the thesis proposes a two-layer optimal dispatching framework that takes into account the switching sequence along with dynamic thermal rating, leading to the effective resolution of congestion issues across various scenarios while maintaining a safety margin. In general, the models and optimization dispatching framework proposed in this thesis can help achieve the optimal power flow for UPSs, and improve its economic, security, and stable operation.
- PublicationNumerical study of heat transfer and flow characteristics of microchannel heat sink with staggered water droplet geometries using water and nanofluids(2024-02)The rapid transition of electronic devices from low performing, low-speed systems to high performance systems with high computational speeds has led to the exponential hike in power density which poses a challenge for effective heat dissipation. To prevent thermal-induced damages in miniaturized electronic devices, the heat dissipation rate must be increased by incorporating heat exchangers with large surface area to volume ratio such as the microchannel heat sink (MCHS). This research sought to augment the thermohydraulic performance of a conventional MCHS using two different approaches: geometrical modification and flow parameter modification. Three-dimensional conjugate heat transfer analyses were conducted using state of the art computational fluid dynamics (CFD) software, ANSYS Fluent 2022, to assess the hydrothermal attributes of water and water-based nanofluids on an MCHS, employing staggered water-droplet geometries. The research focused on single phase laminar flow (Re<1000) through microchannels with hydraulic diameter (D_h) of 750 μm and aspect ratio of 1.5. The thermohydraulic performances of the MCHS were evaluated against different geometric parameters including groove aspect ratio, groove pitch, groove size, and geometry type. Apart from that, the impacts of the nanofluid properties (i.e., nanoparticle type and nanoparticle concentration) on the heat dissipation performance were also examined in the study. The geometrical modifications were found to induce a substantial enhancement in the thermal performance of the MCHS through the promotion of fluid mixing which intensified the thermal exchange between the solid and fluid domains. However, the pumping cost associated with such modifications were higher because of a higher pressure drop penalty. The employment of nanoparticles as fluid additives led to a substantial heat transfer increment, albeit with a higher pumping power requirement. With that being said, the implementation of nanofluids is preferable in comparison to plain water as the advantages greatly outweigh the disadvantages.
- PublicationChinese traffic sign detection and recognition based on lightweight you only look once (YOLO) models(2024-08)Detecting and recognizing traffic signs is crucial for intelligent driving systems, providing essential real-time guidance to drivers. Challenges such as bad weather, lighting, and occlusions hinder traffic sign detection. Conventional algorithms struggle to balance accuracy and real-time performance, leading to the favouring of lightweight deep learning detection algorithms for their automatic feature extraction and low computational cost. This study is based on the classic YOLOv4-tiny and YOLOv5s object detection algorithms, proposing several improvement strategies aimed at developing a more robust model for detecting traffic signs. This research selects the Tsinghua-Tencent 100K (TT100K) dataset and the CSUST Chinese Traffic Sign Detection Benchmark (CCTSDB and CCTSDB2021) datasets for training and evaluating traffic sign detection algorithms. Enhancements include an improved lightweight Better Efficient Channel Attention (BECA) mechanism, an upgraded Dense Spatial Pyramid Pooling (Dense SPP) network, an extra detection head, and optimized anchor boxes. The improved TSR-YOLO model showed significant improvements in precision (96.62%), recall (79.73%), F-1 Score (87.37%), and mAP (92.72%) with a stable FPS of around 81. However, due to its complexity, it is unsuitable for embedded devices. Thus, the study developed Sign-YOLO, which has been improved by a Coordinate Attention (CA) module, a High Bidirectional Feature Pyramid Network (High-BiFPN), and the Better Ghost Module to reduce model size. Sign-YOLO was evaluated on the CCTSDB2021 and TT100K datasets, reducing parameters by 0.13M compared to YOLOv5s, achieving a good balance between accuracy and speed for traffic sign detection.
- PublicationDevelopment of ZnO nanorods on supporting substrates for photocatalyst applications(2024-02)Zinc Oxide (ZnO) nanorods based photocatalyst suffers from performance deterioration over time due to loss of ZnO nanorods in the particle form. In addition, a low cost and rapid synthesis technique is needed for mass production of ZnO nanorods particularly on supporting substrate. In this work, ZnO nanorods (particle and nanorods immobilisation on substrate) were successfully synthesized by solution precipitation technique and direct heating (DH), respectively. The results were confirmed by X-ray Diffraction Spectroscopy (XRD) and X-ray Photoelectron Spectroscopy (XPS) analysis. The small IUV/IVis ratio in Room Temperature Photoluminescence (RTPL) analyses indicate that the ZnO contained crystal defects such as oxygen interstitial, zinc vacancy or oxygen vacancy. The ZnO nanorods demonstrated photodegradation of RhB dye under exposure of UV irradiation, and selectively removal on Cu2+ ions and Ag+ ions. The photodegradation of Rhodamine-B (RhB) dye complied to 1st order kinetic reaction. The scavenger study indicated that OH● free radicals and O2●- free radicals were the dominant species that actively involved in the photodegradation of RhB dye. The ZnO particles demonstrated the highest photodegradation efficiency (PE%) (72%), but deteriorated in the cyclic test. ZnO nanorods immobilised on PET fibre demonstrated decrease in PE% was attributed to reduction of surface area as the ZnO nanorods were stacked on each other. The PE% of ZnO nanorods grown on kanthal wires/meshes were the lowest. This was because of smaller catalyst loading was used in the photocatalytic test. In term of its reusability, ZnO nanorods grown on kanthal wires/meshes were the best. The selection of polymeric flexible substrate or rigid substrate depends on the usage point in the wastewater treatment. Lastly, DH technique is successfully developed to synthesise ZnO nanorods in short duration (15 min), consuming low electrical power (≤0.060 kWh). It is a potential synthesis technique that can be upscale for larger substrate size and mass production of ZnO nanorods for the fabrication of wastewater treatment module.
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- PublicationEquivalent diagonal strut coupled with hybrid plasticity approach for seismic response macro-modelling of clay brick wall infilled frames(2020-11-01)Interaction between reinforced concrete frames and masonry infills under seismic load in Malaysia is often being overlooked by engineers and experts due to the low occurrence and magnitude of earthquake and scarcity of established research studies in the related area. Moreover, no guidance is given by Eurocode 6 and Eurocode 8 on macro-modelling approach of the seismic response of infilled frame. This study aims to provide an in-depth understanding on the seismic behaviour of masonry infilled reinforced concrete frames in Malaysia and to propose macro-modelling for masonry infilled frame through equivalent diagonal strut coupled with hybrid plasticity approach. Under the experimental testing, six half scale single-storey single-bay reinforced concrete frames with and without unreinforced clay brick infills were subjected to lateral monotonic and cyclic loadings. The seismic behaviour of the frame system improved in terms of strength, initial stiffness, energy dissipation and also delay in cracks formation in frame due to the presence of infill. However, the adopted masonry wall system is considered strong, thus induces shear failure in columns. It is discovered that effect of aspect ratio of infilled frame is significant in energy dissipation. Macro-Modelling of masonry infilled reinforced concrete frames using equivalent diagonal strut coupled with hybrid plasticity approach and an improved constitutive backbone law shows good correspondence with experimental result. Under the investigation of reliability of seven equivalent diagonal strut width models using the improved constitutive backbone law, it is discovered that models with similar strut width trends over aspect ratio produce similar responses. All the strut models are able to produce response with reasonable accuracy except Mainstone (1974) model. Seismic performance of a five-storey non-ductile masonry infilled reinforced concrete frames typically found in Malaysia was assessed using incremental dynamic analysis (IDA) with ten ground motion records. The collapse capacity at 16%, 50% and 84% fractiles of IDA curves are 1.0, 1.53 and 2.03, respectively. The maximum drift ratio where dynamic instability is reached ranges between 0.1% to 0.26%. This study has provided a practical elucidation of the interaction between infill and frame for the development of more realistic seismic-resistant design for Malaysia.
- PublicationEnergy Efficiency Readiness Framework For Occupants Of Government Buildings In Melaka(2023-04)Energy sectors are accountable for greenhouse gas emissions and many programmes to improve energy efficiency have been conducted since 1990. Ever since, the state of Melaka, through the Melaka Green Technology Corporation (MeGTC) and the Centre for Education, Training, and Research in Renewable Energy, Energy Efficiency, and Green Technology (CETREE) in 2016, has introduced energy efficiency and labelling programmes (EPCert) in an effort to promote an energy-efficient culture and ultimately control the total energy consumption of buildings in Melaka. Prior studies revealed that organisational readiness plays a crucial role in determining the success of energy efficiency initiatives in buildings. By assessing an organisation’s preparedness to undertake such projects, stakeholders can gauge the potential effectiveness of implementing energy-saving measures. Thus, this study is an initial attempt to investigate the occupants’ readiness in Melaka state government buildings towards environmental and energy-saving awareness practices among occupants. A survey method was employed for data collection. The respondents were building occupants and/or employees at eight major state government buildings in Melaka. A questionnaire was disseminated to the respondents, which generated a 53% response rate. A structural equation modelling-partial least squares approach was performed for the main data analysis.
- PublicationPemodelan dan penganalisaan, alat pembuka buah kelapa bagi suri rumah menggunakan sofwer i-deas(2002-03-01)Recently, computer has becomes an essential tool for the engineering field. Computer Aided Engineering (CAE) has been developed in a rapid rate due to the fact that it has simpified the method use to solve engineering problems compare to the traditional engineering problem’s solving method. Some of the advantages for using computer are shorter time for completing engineering task, able to handle large amount of data and higher precision can be achieved. The ability of computer has been used to analyze the minimum and maximum displacement, stress and strain energy was used when a minimum force are applied. The purpose of this project is to redesign a coconut opener with minimum force applied, less weight, smaller and handier, high safety and more commercials. I-DEAS, a commercial engineering package has been used for simulation. In the beginning, construction of an appropriate boundary condition and simulation has been done. The same step was followed with the new design. At the end, the two results are compared to know which one is better.
- PublicationExploration of image-based stimuli to assess mental toughness among medical students of Universiti Sains Malaysia(2023-05)Mental toughness (MT) is a psychological construct comprised of cognitive, emotional, and behavioural processes that explain an individual’s capacity to cope with stress and predicts optimal performance in adversity. Apart from psychological-based studies, researchers have been shifting to physiological and neuroscience research to advance the knowledge and understanding of mental toughness. These studies require non-invasive modulation of emotion, stress, and cognitive effort induction. This present study seeks to explore a set of image-based stimuli to assess mental toughness among medical students. The study design consisted of four phases. Phase I involved the validation of the MTQ-48 questionnaire. Phase II involved the assessment of mental toughness, depression, anxiety, and stress in medical students. Phase III involved the selection of 156 image-based stimuli from databases such as the International Affective Picture System (IAPS), the Nencki Affective Picture System (NAPS), the Emotional Picture Set (EmoPics), the Open Affective Standardized Image Set (OASIS), the Geneva Affective Picture Database (GAPED), and online licensed no copyright platforms such as Pexels and PxHere. These images were then content validated by panel of experts according to academic related and clinical related medical context. The valence and arousal of normative evaluations were obtained by medical students using self-assessment manikin (SAM). Phase IV involved the evaluation of the stress intensity of the image-based stimuli from Phase III and its relationship with mental toughness, perceived stress, and stress score. Findings from factor analyses stated that MTQ-48 is unreliable for use in medical context as the fit indices do not meet acceptable standards. Consequently, MTQ-10 resulted from the validation process in Phase I had better model fit and used throughout the study. Besides, a significant inverse relationship was found between mental toughness and depression, anxiety, and stress. Out of 156 images, only 149 images were relevant to academic and clinical related medical context and were obtained valence and arousal mean value for each image. 36 images with negative valence were used to evaluate the stress intensity of the images and its relationship with mental toughness, perceived stress, and stress questionnaire. These findings provide evidence that the stress intensity of the set of image-based stimuli was 19% significantly predicted mental toughness, 43.9 % predicted perceived stress and 19.8% predicted stress. Hence, the set of image-based stimuli possibly to be used to assess mental toughness, perceived stress, and stress along with other variables in future research to facilitate a greater understanding of the affective processes associated with mental toughness in medical students.
- PublicationArea optimization in active reference bandgap amplifier layout design(2023-07)In the general design flow of the Full Custom Integrated Circuit (IC), layout design was the backend of the design flow of an Integrated Circuit. Layout design was the geometric form of the schematic circuit and the layout design was transformed into a photolithographic mask layer during the fabrication process. In layout design, the unique needed of Datapath design were Area, Pitch-matched layout, and symmetry in an arrangement. Due to the high cost of materials, area optimization in layout design had become important to overcome challenges such as cost, complexity, and performance. The area of layout design reduced by area optimization to a compact size by following critical requirements and it could be started from the floor planning layout design step. The techniques of area optimization introduced in the project which includes the minimum distance rule, sharing diffusion region and guard ring, sharing well layer, and introduction of legging in the routing step. Euler’s Path also one of the theoretical techniques to determine the placement of the device to get the shortest routing distance. The project required to run physical verifications such as DRC, LVS, and Latch-up to check and ensure the layout design was clean with no errors. The layout design was designed by using Cadence Virtuoso Layout Suite XL and Schematic Editor tool was used to review the schematic circuit for routing and identify the sensitive blocks. Compared to the results with and without area optimization, the overall area layout was reduced by at least 20%, and eliminated the unwanted white space after implementing the area optimization techniques.
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