International Journal of Integrated Engineering
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The Influence of Carbon Powder on the Physical, Mechanical and Absorption Properties of Carbon Foam from Natural Precursor Starch
Full text linkThis study was fabricated the starch-based carbon foam with sodium borate as the blowing agent and reinforced with carbon powder. The effect of carbon powder on the physical, mechanical and adsorption properties was investigated. The temperature of foaming and carbonization was fixed but the carbon powder percentage was varied in the range between 2wt% to 8wt%. The physical properties of the carbon foam analysed by the density and porosity, pore morphology was analysed by using Scanning Electron Microscopy (SEM) and carbon bonding was observed through Fourier-infrared Spectroscopy (FTIR). The percentage of the carbon powder inside the carbon foam influence the properties of the carbon foam. The higher the content of the carbon powder, the higher the bulk density but low porosity. The results of the pore morphology using the SEM proved the size of the pore decreases as the carbon powder percentage increase inside the carbon foam. The FTIR analysis shows the carbon bonding. Furthermore, the maximum stress and maximum force applied also rises as the carbon powder increases. The highest value of maximum stress was achieved by carbon foam with 8wt% of carbon powder which is 1.71345 N/mm² respectively. Since the bulk density is higher, the oil adsorption lower due to small porosity of the carbon foam. The characteristic remains for all parameters when the reusability test implemented by burning the carbon foam. The objectives of the study achieved and the effect of carbon powder to carbon foam proven
Development of a Tiltrotor Propulsion System for Hybrid VTOL Fixed-Wing Drones
Full text linkHybrid Unmanned Aerial Vehicles (UAVs) integrate features from both fixed-wing and multirotor UAVs. The fixed wings efficiently distribute aerodynamic loads while combining aerodynamic properties with the multirotor configuration. A tiltrotor mechanism is necessary to facilitate the transition between hover and forward flight modes. This research focuses on developing a comprehensive tiltrotor propulsion system for a fixed-wing aircraft. Two methodologies were employed: software simulation and experimental testing. A restricted flight test was conducted using a test rig to observe the drone\u27s behaviour at various throttle levels, revealing that each motor produced 2.12 kg of thrust, resulting in a total thrust of 6.12 kg. The drone successfully lifts off at its maximum take-off weight of 3.1 kg. Five potential materials for the components supporting the front and rear motors were tested through simulations, with Polymaker\u27s PolyTerra PLA, a modified polylactic acid material, proving to be the best option. It demonstrated maximum equivalent von Mises stress values of 4.0122 MPa for the front motor supports and 2.8205 MPa for the rear motor supports, along with minimal deformations of less than 0.01 mm. Therefore, the results demonstrate that Polymaker\u27s PolyTerra PLA is an optimal material for the support components of the front and rear rotors, ensuring structural reliability and suitability for hybrid vertical take-off and landing (VTOL) fixed-wing drones, as evidenced by its exceptional performance under simulated and experimental conditions
Computational Intelligence and Load To Source Ratio Index Based Technique for Voltage Security Restoration
Full text linkVoltage security remains a critical concern in power systems, as voltage instability can lead to service disruptions and cascading failures. This paper presents an advanced computational intelligence technique based on the load-to-source ratio index, integrated with Evolutionary Programming (EP) to enhance voltage stability. Unlike conventional methods, this approach optimizes reactive power dispatch (ORPD) across multiple configurations to improve voltage levels throughout the network. The technique was validated on the IEEE-30 Bus Reliability Test System under various loading conditions. Results show significant improvements in the index for weak buses, with an increase from 10.9667 to 24.3144 at the critical Bus 29, leading to improved voltage levels across the system. Additionally, the method offers enhanced flexibility by assessing multiple ORPD scenarios, allowing system operators to choose the optimal configuration for different network conditions. These findings suggest that the proposed method not only improves voltage security but also provides a robust, adaptable solution for practical power system operations
Turbidity Trends in 20 Water Treatment Plants Across Sabah, Malaysia: Implications for Sustainable Water Resource Management
Full text linkWater Treatment Plants (WTPs) play a vital role in ensuring safe drinking water by removing contaminants, with turbidity serving as a key indicator of raw water quality. However, turbidity levels in raw water sources are increasingly influenced by extreme weather events and anthropogenic activities, presenting challenges for effective water treatment. This study aims to assess turbidity trends and identify contributing factors in WTPs across Sabah, Malaysia, to support more sustainable water management practices. Turbidity data from the WTPs, spanning 1 to 8 years, were analysed, supplemented by time-lapse satellite imagery to assess upstream catchment conditions wherever possible. Data were categorised into four administrative divisions - West Coast, Kudat, Interior, and Tawau divisions - and examined for temporal and spatial variations. The analysis revealed frequent turbidity spikes, particularly in the Tawau and Interior divisions, with some WTPs, such as Kalabakan and Beaufort I & II, recording levels exceeding 1000 Nephelometric Turbidity Units (NTU), which is the operational shutdown threshold used by WTPs to prevent treatment failure and equipment damage. Kalabakan recorded a peak turbidity of 2,264 NTU, while Beaufort I and II reached 2,528 NTU, more than twice the downtime threshold. These elevated levels were closely linked to extensive land clearing and agricultural activities. The study underscores the importance of integrated water resource management, including erosion control, reforestation, and stricter land-use regulations. To improve operational resilience, real-time turbidity monitoring and predictive modelling are recommended to enhance WTP resilience and ensure a sustainable water supply in tropical regions amidst intensifying environmental pressures
On Thin Flexible Wideband Printed Vivaldi Antenna for Sub-6 GHz Wearable Applications
Full text linkThe growing adoption of Body Area Networks (BANs) significantly enhanced the desire of wearable antennas. This study introduces a flexible wearable printed antenna based on an antipodal Vivaldi structure fabricated on a hybrid polyimide-polyester substrate utilizing screen printing fabrication technic, as well as a flexible dual-ring antenna utilizing copper tape and a polyester substrate. Compare to rigid antennas, flexible wearable antennas require meticulous fabrication and measurement processes due to their structural sensitivity. This paper provides a comprehensive analysis on the procedure of fabrication and considerations during measurement of the flexible wearable antennas, alongside a comparative analysis between them. These antennas exhibited satisfactory free-space performance, covering key 5G NR bands, including n48, n77, and n78. Printed antenna demonstrated wider resonance bandwidth oppose to the copper tape antenna and exhibited a higher degree of alignment among simulation and measurement. These findings indicate that the printed antenna offers superior performance and durability. To ensure its suitability for wearable applications, outcomes of the antenna was critically assessed placing on-body and under structural deformation. The measurement results validated the antenna\u27s satisfactory performance, demonstrating a resonance bandwidth of 740 MHz when placed on the back, 710 MHz on the chest, and 650 MHz under a bending radius of 50 mm. Additionally, the measured results exhibited strong agreement with the simulation. Based on these assessments, the printed antenna is considered a feasible candidate for wearable applications
Comparison of Advanced Modulation Techniques of Free Space Optical Link for Ground-to-Train Communication
Full text linkNowadays, mundane tasks are becoming more \u27on-the-go\u27, leading to the increasing popularity of public transport like high-speed trains. Internet access for these trains has increased, requiring the deployment of free space optical (FSO) communications in ground-to-train (G2T) communication. However, there is a lack of research on FSO links for railway communications. Single tracks mathematical models have been applied to address this need. Multiple attenuation intensities were tested for various weather conditions (clear, drizzle, strong rain, rainstorm and light fog), and three modulation techniques which are NRZ, OFDM 4-QAM, and OFDM 4-QPSK at 10 Gbps were implemented to improve link performance. Geometric parameters were optimized, and models were assessed for transmission distance and received optical power. The performance of the modulation techniques has been evaluated at BER of 1x10-9 for NRZ and BER of 2.8x10-3 for OFDM 4-QAM and OFDM 4-QPSK using the Optisystem®. Simulation results show that with a slightly lower BER, in strong rain condition for 4-QPSK have a higher ROP of -2.7 dBm compared to -3.7 dBm for 4-QAM. However, a few improvements can be made in future research, such as using multi transmitter concepts such as Multiple Input Single Output (MISO) to improve G2T-FSO performance and extend transmission distance coverage
Combined Influence of Metakaolin and Palm Oil Fuel Ash on the Heat of Hydration and Permeability of High Performance Concrete
Full text linkUtilizing metakaolin (MK) and palm oil fuel ash (POFA) mitigates the negative impacts of high content cement in high performance concrete (HPC). This research aims to investigate the heat of hydration (HOH) and water permeability of HPC blended with MK and POFA as cement substitutes. Three concrete mixtures namely a control made with 100% ordinary Portland cement (OPC), optimum MK; and optimum blend of MK and POFA were prepared. Subsequently, the temperature rise due to HOH and water permeability were evaluated. The results demonstrated that using 15% MK with or without 20% POFA reduced the peak temperature and coefficient of water permeability of HPC compared to control concrete. The findings suggest that incorporating MK and POFA in HPC is beneficial for mass concrete to prevent thermal cracking and for water-retaining structures to block permeable pores.
Performance of Azadirachta Indica as Bio-Flocculant in Reducing Turbidity Concentration from Landfill Leachate
Full text linkIt is widely established that the amount of municipal solid debris produced daily continues to rise. As a result, municipal solid waste (MSW) landfills struggle with leachate formation, which puts groundwater and surface water at serious risk. Leachate is a liquid that has extracted dissolved and suspended materials from waste and travels through landfills. Dumping landfill leachate directly into a body of water or the environment puts the ecology and public health in danger since it contains high levels of COD, pH, ammonia nitrogen, turbidity, and heavy metals. Therefore, finding and offering an efficient landfill leachate treatment is undoubtedly required. The purpose of this study is to evaluate the performance of the bio-flocculant Azadirachta Indica (bf-Ai) as a flocculant in the coagulation-flocculation process for the treatment of landfill leachate under various experimental circumstances. Additionally, the performance of conventional coagulant alone, which is alum, will be experimented and compared with a combination of alum (as coagulant) and Azadirachta Indica (Ai) as bio-flocculant (alum + bf-Ai). Based on this study, the combination of alum + bf-Ai recorded higher removal of turbidity, which is 64% compared to alum alone (62%) at raw pH of leachate and the dosage of alum + bf-Ai as 0.8g and 5g, respectively. Additionally, reduction in the usage of alum dosage can also be seen in this combination, which decreases from 1.4g to 0.8g only. This reduction is a positive sign since alum alone has produced hazardous sludge (secondary pollutants) damaging the environment and human health. Thus, further research should be conducted on the potential of Ai as a bio-flocculant aid
Factors Affecting the Rate of CaCO3 Precipitation in Biocementation of Heavy Metal Contaminated Soil
Full text linkGround improvement methods using physical and chemical treatments are considered effective but costly, involving large engineering work and may pose serious environmental problems. Therefore, biocementation using enzyme-induced calcite precipitation (EICP) technique is introduced. The efficiency of EICP is influenced by the production of calcite carbonate, CaCO3 and governed by multiple factors. While some preliminary studies have been done on variety of soil types, none the them were performed on heavy-metal contaminated soil. This paper presents the research conducted on factors affecting the CaCO3 precipitation in biocementation of mining waste collected from a copper mine in Sabah, Malaysia treated using EICP solution, cured in a leaching cell and tested using inductively coupled plasma optical emission spectroscopy and acid washing test. Results concluded that factors affecting the production of calcite carbonate content are the cementation concentration (1.0M > 0.5M), degree of compaction (70% MDD> 80% MDD) and curing temperature (25 ⁰C > 15 ⁰C > 5 ⁰C). Meanwhile, immediate production is observed (1-day curing) indicating that curing time is not a significant factor. Hence, the results proposed that the optimum production of CaCO3 for treatment of heavy metal in contaminated soils is at cementation solution of 1.0M, compacted at 70% MDD and cured at 25 °C temperature
Progressive Methods of Finishing the Dovetail Grooves of Aircraft Engine Compressor Disc
Full text linkThe paper analyses the causes of compressor disc failures in aircraft engines. The high-pressure compressor discs were made of a nickel-based heat-resistant alloy, HN73MBTYu-VD. The complexity of the rim profile and the high level of loads create conditions for the development of fatigue cracks. Fractographic analysis of fractures has shown that the most dangerous cracks occur in the sharp corners at the base of the intergroove protrusions, which can lead to the tearing off of disc parts. The purpose of this study was to evaluate the effect of the optimal combination of finishing the groove forming surfaces on the safety factor of the rim elements of high-pressure compressor discs. Residual stresses were investigated by the layer-by-layer removal of thin metal layers using electrochemical polishing of the groove bottoms. To determine the stresses arising in the acute angle zone of the groove, the finite element method was used. The endurance limit of the specimens was determined after 2×10⁷ loading cycles. It has been established that the optimal combination for the finishing stage of disc manufacturing includes sequential treatment with polymer-abrasive brushes, hardening with steel balls in an ultrasonic field, and pneumatic blasting with glass microbeads. Finish-hardening treatment improved resistance to fatigue crack nucleation by creating a certain depth of plastic deformation in the surface layer, inducing significant compressive residual stresses, improving surface roughness, and increasing microhardness. After this treatment, the safety factor of high-pressure compressor discs increases by 1.8 to 3 times. The paper presents a model for the safety factor of compressor discs with dovetail grooves, which takes into account technological residual stresses and operating conditions