International Journal of Integrated Engineering
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Mesh Refinement for Dynamics Airflow in Health Care
Get PDFThis study explores using computational fluid dynamics (CFD) to optimize ventilation in healthcare, with a focus on mesh refinement for accurate airflow analysis. The goal is to reduce airborne contaminant spread, which is crucial during COVID-19. Ventilation in healthcare ensures air quality and minimizes pathogen transmission. The research analyzer analyzes mesh element size\u27s impact on airflow accuracy in simulated hospital wards with two coughing patients. The optimal mesh size is determined for reliable predictions. Mesh refinement enhances accuracy in critical zones. The k-epsilon turbulence model is chosen for low error. Experimental validation shows temperature discrepancies, likely due to simulated manikins lacking clothing insulation. Air velocity measurements show minor variations within an acceptable range. Further research on various ventilation configurations and airflow rates in real hospital conditions is crucial. Addressing these limitations optimizer optimizes healthcare ventilation, enhancing safety and infection control
Reliability Evaluation of Power Electronic Inverter Using Cutset Approach
Get PDFThe development of PV systems for the generation of renewable energy has been gaining a lot of importance in present-day research. Moreover, probabilistic analysis of the various configuration of PV cells, Power Electronic converters, etc. has been considered as the potential area of research with the appropriate assumptions. Evaluation of Basic Probability Indices (BPI) and Probabilistic Measures (PM) of an inverter configuration has been dealt with in the literature by considering the failure of all components will lead to inverter failure, treating all such components in series from Probabilistic Logic Diagram (PLD). However, the evaluation of BPIs and PMs has not been dealt with considering the operating strategies of the inverter. In this paper, it is proposed to deal with the evaluation of the BPIs and PMs for single-phase full-bridge inverter with R and R-L Load conditions and the results of the proposed methods using cutsets will be compared with an existing method
Manipulating the Acoustic Characteristics of Kenaf as a Sound Absorber by Modifying the Thickness and Air Gap
Get PDFThe purpose of this study is to provide a better understanding of the material properties of kenaf fibre from the National Kenaf and Tobacco Board (NKTB) and investigate the performance of kenaf fibre as a material for sound absorption. Non-woven kenaf fibre from the NKTB is a material made from the fibres of the kenaf plant that is processed into a non-woven form. The fabricated samples were made of 65% kenaf fibre and 35% Bico (Polyester) as the binder. Non-Woven kenaf fibre is produced using a Thermo-bonding machine and through several mechanized processes. Bico (Polyester) will act as a low melt synthetic fibre that is melted during the Thermo-bonding process to attach the kenaf fibre. The acoustical properties involved several components, namely the sound absorption coefficient and noise reduction coefficient. It has been indicated that the sound absorption coefficient and noise reduction value for sample 50 mm at middle range frequency (500 Hz-1000 Hz) can be improved by increasing the thickness and air gap. At the end of the study, a comparison of acoustical performance between kenaf fibre properties for sound absorption. The results demonstrated that the performance of kenaf fibre was comparable with another material. This shows that kenaf fibre has a big potential to be made as an alternative material for sound absorber. This research provides knowledge on the acoustical properties of kenaf fibre that contribute to the consumption of natural fibre as biodegradable, environmentally friendly, safe, and cost-efficient.
 
Low Quiescent Current 110 nm Capacitorless Low Dropout Voltage Regulator with Wide Load Range
Get PDFRecent development in internet of things (IoT), sensor-based mobile devices, implantable devices and smart wearables have fueled the demand for power efficient and compact system-on-chip (SoC) solutions, causing power management in integrated circuit (IC) designs to become crucial. As low dropout (LDO) voltage regulator has become one of the key components in power management systems, capacitorless LDO (CLDO) voltage regulator is also becoming more popular due to its compactness which offers better power and cost effectiveness compared to conventional LDO regulators. Power durability has become critical because longer battery life is highly preferred in portable devices, and this highlights the importance of minimizing the power consumption of the devices so that the battery discharges at a slower rate. An effective way to reduce the power in a CLDO regulator is to keep its current flow during idle mode, which is called the quiescent current, at a minimum level. This paper presents a low quiescent current CLDO regulator operating at a nominal voltage of 1.2 V with regulated output voltage of 1 V utilizing the 110 nm CMOS technology. The proposed CLDO regulator achieved a low quiescent current of 5.18 µA with a wide range of load current up of 200 mA at maximum and 80% improved line regulation from the previous work with the same voltage requirements. The single digit micro-ranged quiescent current greatly contributes in minimizing power consumption during the idle mode of the CLDO regulator which can be within single digit micro-Watt range where ultra-low power applications operate, thus prolonging the battery life, whilst the wide load range provides flexibility for the proposed CLDO regulator to power a larger range of circuits to drive with better line regulation and relatively good PSRR at low frequency range. 
The Properties of Hydroxyapatite Derived from Carbonate Eggshell Waste Through Ball Milling and Heat Treatment Method
Get PDFSynthetic calcium phosphate, particularly hydroxyapatite (HA), has been used in various medical applications due to its biocompatibility and bioactivity. With time, increased interest in the development of HA from natural resources has started to emerge to produce more sustainable biomaterial precursors. HA has been successfully prepared from biogenic waste as the calcium precursor via extraction of calcium oxide from eggshells, seashells, and animal bones (cow, chicken, fish) via the wet method. The dry process, particularly solid-state reaction, has been least preferred due to the tendency of powder contamination and non-homogeneous powder mixing. However, with the proper processing regime, this method can produce pure HA on a mass scale with improved properties as it does not require precise control conditions. In this work, HA was synthesised from eggshell wastes through mechanochemical activation and heat treatment processes. The calcium precursor in pure calcium carbonate (CaCO3) was extracted from eggshells through calcination. Then, the Calcium Hydrogen Phosphate Dihydrate (DCPD) as phosphorus precursor was added to the calcined eggshells via a simple mechanochemical route for 2 hours, and the obtained powder mixture was subjected to heat treatment at 800°C to obtain pure HA. XRD analysis confirmed the formation of phase pure HA in the synthesised powder with an average crystallite size of 26.35 ± 0.1 nm and an average agglomerated particle size of 520 nm. Energy Dispersive X-ray (EDX) analysis has validated the elemental composition of synthesised HA with a Ca/P ratio of 1.76, which closely resembles pure HA with a Ca/P ratio of 1.67. Hence, through calcination, eggshell waste in pure CaCO3 form has been successfully utilised as a sustainable calcium precursor in producing HA via a dry method approach with high potential as a biomaterial for biomedical applications and has indirectly contributed to cost reduction of materials processing
The Effect of Polysulfone-nanosilica Coating on Mechanical Properties of Kenaf Fibre-Reinforced Polymer Composites
Get PDFNatural fibre-reinforced polymer composites have gained significant popularity in various engineering applications, replacing traditional synthetic fibre composites. Due to their desirable characteristics, these composites find extensive use across diverse sectors. This study explores Kenaf fibres\u27 potential-based reinforcement material in polymer composites. The Kenaf fibres are laminated with polyvinyl ester resin, forming a plant-based fibre-reinforced polymer (FRP) composite. Additionally, the research investigates the impact of a thermoplastic coating, namely polyethersulfone (PES), on the mechanical performance of the Kenaf fibre-reinforced polymer composites. PES, a versatile thermoplastic material, holds promise for enhancing the composite\u27s properties. The fabrication involves a compression moulding technique, where polyvinyl ester resin acts as the adhesive agent, effectively bonding the PES thin film with the Kenaf fibres. To comprehensively assess the mechanical performance and durability of the thermoplastic coatings, the composites undergo a series of tests: tensile, flexural, interlaminar shear strength (ILSS) and impact tests. Remarkably, the study reveals that the incorporation of polyethersulfone significantly reinforces the strength of the Kenaf fibre-reinforced polymer composites. Both the PES coating and the PES-nanosilica coating demonstrate positive effects on the mechanical properties of the Kenaf FRP composites, leading to notable enhancements in flexural, tensile, impact, and interlaminar shear strength. Introducing nanosilica particles yields further improvements, surpassing the benefits of the PES-based coating alone. The findings from this research emphasise the potential of PES coating and nanosilica in enhancing the mechanical performance of Kenaf fibre-reinforced polymer composites. These results contribute to the domain of sustainable engineering materials, providing valuable insights for developing and optimising natural fibre-reinforced composites in various industrial applications
Optimizing Hydrophilicity in NiO/Graphene Composites Via Stearic Acid Treatment for Humidity-to-Energy Applications
Get PDFConverting water molecules into energy, this research field has garnered significant attention, yet it is still in its early stages of exploration. The main challenge in humidity-to-energy development is the effectiveness of material in water absorption. This article presents a study on surface modification through stearic acid treatment aimed at optimizing the hydrophilicity of hygroscopic material, thereby improving humidity energy harvesting performance. Here, we successfully synthesized a novel NiO/Graphene on cellulose substrate (NiO/Gr/cellulose) as the hygroscopic material using the sonicated solution immersion method. A humidity-to-energy device was fabricated by utilizing the NiO/Gr/cellulose, yielding an output voltage of 2.26 mV, a current density of 0.18 nA/cm², and a power output of 0.51 pW at 75% relative humidity. This research highlights the potential of NiO/Gr/cellulose with sufficient hydrophilicity as a promising hygroscopic material, offering significant future prospects in humidity energy harvesting technology
Enhancement of Sensing Performance for Alcohol in Aqueous Solution Using Tapered Optical Fiber Coated with Polyaniline Via Air-Brushing Technique
Get PDFTapered fibers with superior properties can be used in sensing applications such as humidity sensors, temperature sensors, and refractive index sensors. The main objective of this work is to investigate the influence of Polyaniline (PANI) as a coating in the fabrication of a polymer microfiber for the detection of different concentrations of methanol, ethanol, and propanol. In this study, a high-quality tapered optical fiber is fabricated using the flame-brushing technique and the microfiber is then coated with the polymer Polyaniline (PANI) to detect different types of alcohol at various concentrations. It was found that the sensor using PANI as the coating material on the tapered optical fiber exhibited higher sensitivity to concentration changes of aliphatic alcohol solutions than the bare tapered optical fiber. The improvement in sensitivity for methanol, ethanol, and propanol is 80.17%, 106.43%, and 42.92% respectively. A sensitivity of 0.9755 dBm/%, 1.06 dBm/%, and 1.039 dBm/% for methanol, ethanol, and propanol respectively was achieved by using a tapered PANI-coated optical fiber with a diameter and length of 4 µm and 5 mm respectively. The digital microscope (DM) confirmed the successful coating of PANI on the tapered microfiber which helped to enhance the performance of the sensor. Overall, this work has effectively demonstrated a conductive polymer-coated optical microfiber sensor for alcohol detection that is inexpensive, effective, and easy to set up
Elastic Stress-Strain Behaviour of Concrete with Potential Pineapple Leaf Fibre-Reinforced
Get PDFIn the stress-strain curve, the stress in the linear region of concrete increases when reinforced with fibre reinforcement. This research aims to investigate the potential of natural fibre from pineapple leaves as reinforcement in concrete regarding its elastic modulus. The natural fibre of pineapple leaves has good tensile strength and is not inferior to the artificial fibre commonly used in fibrous concrete. This research used a pineapple leaf fibre (PLF) composition of 0.04%, 0.09% and 0.15% wt of cement with a water-cement ratio of 0.38. The compressive strength applied is only limited to 40% of the design concrete strength to see the stress-strain character in the elastic region of the pineapple leaf fibrous concrete. The research results show that the amount of pineapple fibre 0.15% provides higher strength and 0.04% and 0.09% fibre in line with ACI and Eurocode. During the hardening process, concrete contains pineapple leaf fibre. The stress is higher than normal concrete for 7 days. Normal concrete begins to approach the stress of fibre concrete when it is 28 days old. Pineapple leaf fibre in concrete contributes to strength even when the concrete is at an early age
Briquette Shape Roles in Carbothermal Reduction Process of Limonitic Laterite Nickel
Get PDFCarbothermic reduction of laterite nickel ore is currently the focus of many researchers. This process uses a relatively lower temperature of operation than the smelting. Therefore, the carbothermal reduction process has a relatively lower primary energy demand and CO2 gas emissions. This research examines the appropriate briquette form to achieve the optimum concentration, recovery of nickel, and selectivity factors of nickel, as well as analyzes the compounds/phases formed. The briquette in this study was formed into three different geometries, i.e., the pillow, spherical, and cylindrical forms. First, this research was carried out by mixing the prepared materials and forming them into selected briquette forms. Second, the formed briquettes were put into a crucible. Third, the coal-limestone bed mixture was used to cover the briquettes. Then, the carbothermic reduction process was started by heating to 700 oC for 2 hours and continued to 1400 oC for 6 hours. Finally, the magnetic separation process was performed to separate the reduced briquettes. As a result, the pillow-shaped briquette obtained better results at 6.74% Ni, with a nickel recovery of 96.20% and a selectivity factor value of 10.39. The compounds formed after carbothermic reduction process products include FeNi, Fe3Si, and SiO2. In a spherical-shaped briquette, Fe3O4 and Mg2SiO4 were found in the reduced product, indicating impurities in the reduced briquettes