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    Damage-based fretting wear model for life prediction of steel wire ropes

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    Steel wire ropes are designed with different configurations and arrangements to suit various applications. In most manufacturing industries, fatigue test is often conducted to assess the reliability of new wire ropes. The fatigue test is time-consuming and requires a large collection of stress-life data to suit various wire rope designs and stress ratios. Furthermore, during the reliability test, the sample wire rope is subjected to tension-tension fatigue loading and this would induce fatigue damage by fluctuating stresses in the wire material. The current fatigue life prediction method does not take into account the combined bulk fatigue due to tensile stress fluctuations and fretting wear due to relative sliding and contact stress between the stranded wires, which is the dominant damage mechanism in a wire rope. Therefore, the objective of this study is to develop a validated methodology for fatigue life prediction of newly-designed steel wire ropes that incorporates both bulk fatigue and fretting wear conditions. The interaction between wires is explicitly addressed through the friction and fretting wear damage coefficient. Drawn, bare (non-galvanized), as-received high carbon steel wires and steel rods (undrawn) are used as the reference materials. A series of metallurgical and mechanical testing including microstructure analysis, tensile, interrupted fatigue, hardness and sliding wear tests are conducted on the reference materials to obtain the required properties of the wire materials as the model parameters. The model is then integrated into the user material subroutine (UMAT) of the Abaqus finite element analysis (FEA) software to predict the fretting wear and fatigue life of the drawn steel wires. The load cycle block method with each block representing 10,000 cycles is employed for computational efficiency. The associated coefficient of fretting wear damage, cf was determined through calibration with reported experimental data and it was found that when cf = 0.10, the simulated wear depth showed a good agreement with the measured data. The criteria for material removal due to wear and fatigue fracture were established. The material is removed due to wear once the element reaches the terminal value of Dc = 0.90. A new fatigue fracture criterion is proposed based on the total dissipated energy, Ed when the wear depth is 1/3 of the initial wire diameter. Once the energy reaches the critical value of Edc = 32-34 J, fatigue fracture is expected to occur. The number of cycles associated with Edc is taken as the fatigue life of the wire. The calibrated fretting wear damage model was then examined for the reliability of 1x7 steel wire rope samples and the simulated fatigue life showed a good agreement with the measured data by Kiswire. This indicates that the fretting wear damage model is able to quantify the fatigue response of the newly-designed steel wire ropes with various configurations prior to the production of samples for the reliability test. In addition, the design, size, arrangement, and configurations of the wire rope could be improved at an earlier stage based on the reliability requirements. This will increase production productivity and significantly reduce the cost involved in the production and disposal of the steel wire rope that did not achieve the reliability criteria

    Flexible organic polymer matrix composite antenna for wireless local area network application

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    The growing demand for flexible antennas has resulted in intensified research on new materials for flexible antennas. The flexibility of antennas is a well-known requirement in wireless body area networks (WBAN), vehicle navigation system and wireless local area networks (WLAN) to improve seamless integration on devices. Compared with conventional rigid antennas, conformal antennas provide a larger coverage area with a broad beam radiation pattern due to the increase in the area of transmission and reception. This research aims to develop and explore a new organic polymer matrix composite (PMC) antenna with organic fibre to replace synthetic polymer composite which may release harmful chemical and also non-biodegradable. Organic PMC is not only low cost but able to promote sustainability for the environment. Size miniaturization also needs to be achieved for a more compact size antenna and also to enhance the bandwidth. The proposed antenna is a flexible monopole antenna based on organic PMC material produced from natural Basalt fibre and it proved to manage in operating at frequencies of 2.45 GHz and 5.8 GHz for WLAN application. The characterized Basalt composite substrate has a thickness of 0.42 mm, dielectric constant of 3.105 and tangent loss of 0.0299. The vacuum infusion technique is used to manufacture the composite material as this technique can increase the accuracy of fiber to resin ratio and give consistent resin usage. Before vacuum infusion, a layer of conductive fabric named ShieldIt with adhesive glue on its bottom layer will be ironed onto the basalt fiber fabric. Then, two layers of basalt fiber fabric with a layer of conductive fabric on the top layer were placed on the mold before vacuum conditions are created. Epoxy resin and hardener were then mixed in a ratio of 10:6. Vacuum pressure was turned on and pushed the epoxy mixture to the laminate through the tubing. The defected ground structure (DGS) were implemented to improve bandwidth and coplanar waveguide (CPW) as antenna feeding method. Top layer radiating element is conductive fabric and the lasercut machine cut out the antenna pattern precisely. Measured antenna gains at 2.45 GHz and 5.8 GHz are 3.865 and 4.8 with efficiency of 62.63% and 68.07%, respectively. As a flexible antenna, the bending test proved that the antenna performance did not compensate for bending at different curvature radii

    Review of risk management in Rent to Own (RTO) scheme in Malaysia

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    This paper focuses on the review of risk management in Rent to Own (RTO) scheme in Malaysia. The objectives are to review the risk management factors in RTO scheme and the strategies to overcome the risk. This study employs a desktop study by collecting the research papers and data in the online databases. RTO Scheme is a concept that employs the rental market like Private Rented Sector (PRS) in the properties that allows ownership after the tenancy period has been expired. The RTO scheme is a type of financial schemes that allows property leasing for between twelve (12) months to five (5) years and ownership upon the maturity of the leasing period. This is an initiative by the Economic Planning Unit (EPU) and the Ministry of Housing and Local Government (MHLG) to implementing the National Housing Policy 2018-2025. The RTO scheme is for home buyers to have financial planning to rent before they buy. The calculation of the mortgage loan for RTO Scheme is based on the rental income and the rental deposit. Additionally, preliminary case study has been conducted to the RTO schemes through onsite and interview with the Developer. The results are to review the risk factors in the RTO Scheme and the marketing strategies. The outcomes of the research are to give input to the house buyers to be confident to buy houses under the RTO Scheme

    Comparison of calcium hydroxide treated and untreated pumpkin flesh at different dehydration temperature

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    Pumpkin is widely planted worldwide, including Malaysia. Some regions have the limitation of oversupply or limited supply for fresh pumpkin. This has raised the urge to produce pumpkin derived products to avoid spoilage and wastage of fresh pumpkin and to cater the high demand from consumers due to its known health benefits. Dehydration is one of food preservation method. Starting from food dehydrating directly under sunlight to developing time saving and cost effective technologies with the aim to improve the quality of dehydrated products. Food dehydrator is a practical technology that can be used to dehydrate pumpkins. It could be used to dehydrate foods at different temperatures with a good air aeration to accelerate the dehydrating process. Four temperatures (50℃, 60℃, 70℃ and 80℃) had been tested to dehydrate pumpkin flesh in the present study. The pumpkin flesh was treated with calcium hydroxide (Ca(OH)2) for better dehydration and food preservation. The dried pumpkins were then ground into powder for storage. The quality of pumpkin products was proven by extracting bioactive components from dried pumpkin using ethanol extraction. The good quality of dried pumpkins was also determined for its biochemical compounds such as ß-carotene, riboflavin, caffeic acid, and quercetin by HPLC. The antimicrobial activities of the extracts towards four microorganisms (Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, and Klebsiella pneumonia) were also analysed using disc diffusion method. Dehydration of pumpkin flesh was found to exhibit falling rate pattern, which is common in the dehydration of agricultural products. The treated pumpkin flesh that dehydrated at 70°C was able to produce the highest extraction yield (73.54%). However, the degradation of bioactive compounds could be happened during the process of pre-treatment, dehydration, extraction and storage. The explanation was given to the observation in the present study because the assigned compounds could not be detected and no significant inhibition was observed for the selected pathogenic microorganisms. Although dehydration was successfully carried out, the quality of dried pumpkin was not satisfied. Therefore, it is recommended to improve the pre-treatment and extraction techniques to ensure high quality of dehydrated pumpkin flesh for human consumption

    Synthesis and characterization of lead-free perovskite thin film deposited using spin coating technique

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    Perovskite solar cell (PSC) technologies are viewed as promising innovation and have sparked a lot of interests due to their efficiency, ease of manufacture, and low energy and environmental impacts. The performance of PSC has improved quickly in recent years, with the current record of 25.6 % power conversion efficiency (PCE). The purpose of this thesis is to fabricate methylammonium tin triiodide, CH3NH3SnI3 perovskite thin film using spin coating technique. By manipulating spin rate and the precursor concentration, the structural and optical properties of microscope perovskite thin film were investigated and characterised using scanning electron -SEM, atomic force microscope-AFM, X-ray diffraction-XRD, and Ultraviolet-Visible spectroscopy respectively. The XRD result showed that CH3NH3SnI3 perovskite material exhibits intense peaks corresponding to the plane (100) and (200) at the angles of 14º and 28º. The results from AFM revealed that perovskite film fabricated at 2000 rpm with 1.0 M of precursor concentration showed a uniform and consistent surface structure with a root mean square roughness (Rrms) of 20.70 nm. From SEM analysis, perovskite thin film fabricated at 2000 rpm with precursor concentration of 1.0 M showed a significant homogeneous and uniform layer. From UV-Vis data, the highest absorption spectra was demonstrated by the perovskite film with 1.0 M concentration and fabricated at 2000 rpm spin rate. By controlling the spin rate and precursor concentration during the fabrication process, it was shown that 2000 rpm and 1.0 M are the best parameters for good perovskite thin film quality for solar cell application

    Effect of nanoparticles in cuttings transport perrformance of water based muds at eccentric drill pipe

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    One of the major issues for drilling operations is achieving effective cuttings transport, particularly in extended-reach drillings (ERD) with horizontal and highly deviated sections. The main objective of the present study is to investigate and compare the application of different nanoparticles (NPs), such as nanosilica (SiO2), aluminium oxide (Al2O3), magnesium oxide (MgO), and copper oxide (CuO) for improvement in cuttings transport in a full wellbore section at both eccentric and concentric drill pipes. Water-based mud (WBM) was mixed with 0.13 and 0.26 wt.% of each of the NPs to create NP drilling fluids, which were then tested for rheological and filtration characteristics. The flow loop is 20 feet long, 2.4 inches wide (2.4-in. ID), and 1.4 inches thick (1.4-in OD). By circulating the tested fluid samples into the test section vertically to horizontally while controlling the flow rates (1.9, 2.15, 2.4 L/s), cuttings sizes (1.10–1.4 mm; 1.5–1.7 mm; 1.8–2.0 mm), hole angles (0, 30, 60, and 90o), and drill pipe eccentricity (e = 0; e = 1.0), the cuttings transport experiments were carried out. Simulating actual field circumstances is the aim of such a change in the operating parameters. The parameter used to assess hole cleaning is known as the "cuttings transport ratio (CTR)," which is calculated as the weight of recovered cuttings divided by the weight of injected cuttings. According to the findings, conventional WBMs' rheological properties are successfully improved by NPs, which improves borehole cleaning and drilled cutting suspension. With a higher NP concentration, the WBM's filtration capabilities were enhanced. The ideal concentration of NPs for rheological characteristics is 0.13 wt.%, whereas the ideal concentration for filtration control properties is 0.26 wt.%. In contrast, MgO yielded the lowest CTR, followed by SiO2, Al2O3, and drilling muds containing CuO mud samples produced the highest CTR. Their unique morphologies and various interactions with bentonite in the fluid system were linked to these variations in CTR. The cuttings are best transported at 0°, then 30°, next 90°, with 60° being the least-cleaning hole angle. Cutting behaviour is heavily influenced by the slope and geometry of the hole. At various flow rates, the concentric annulus provided a greater CTR than the eccentric drill pipe. However, flowrate is a major factor in eccentricity, and flow rates greater than 2.4 L/s may result in higher CTE pipe eccentricity. This research is the first effort to assess the use of various NP additions to improve the capacity of drilling fluids to circulate and move drilled cuttings out of the wellbore. With the help of NPs, the cuttings transport performance of WBM can be reasonably improved, and the project risks may thus be reduced. Thus, the study is expected to open new directions in developing NPs material as potential cuttings transport agents

    Effects of palm oil mill effluent anaerobic sludge pretreatment temperature on biohydrogen production and the inoculum microbial community

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    Biohydrogen production yield from dark fermentation could be improved by inhibiting interspecies hydrogen transfer to methanogens, homoacetogens and suppress non-biohydrogen producers as metabolic competitors. Heat pre-treatment has been extensively used for this purpose. In this study, the effects of heat pre-treatment temperatures on the performance of mesophilic biohydrogen dark fermentation system and the inoculum microbial community were evaluated, using POME anaerobic sludge as inoculum. Heat pre-treatment of the anaerobic sludges were conducted at 50°C, 65°C, 80°C and 100°C for 30 minutes. Biohydrogen production was evaluated under batch fermentation (30°C, initial pH 5.5-6.0, 180 rpm). Shotgun metagenomics analysis was carried out on the raw, untreated and treated sludge inoculum after fermentation. The results showed that pre-treatment of the inoculum at 65°C produced the highest biohydrogen yield of 0.67 mol H2/mol hexose followed by pre-treatment at 80°C which produced 0.62 mol H2/mol hexose. Untreated inoculum yielded 0.30 mol H2/mol hexose while 50°C and 100°C pre-treated inoculum produced less than untreated anaerobic sludge. Methane was not detected in any of the fermentation reactions. Shotgun metagenomics revealed that inoculum heat pre-treatment temperatures influenced the microbial communities in biohydrogen production fermentation. Inoculum pre-treated at 65°C and 80°C were enriched with the most biohydrogen-producing taxa, mainly spore-forming Clostridia which generate biohydrogen via butyrate-type fermentation pathways, producing butyric and acetic acids. Untreated anaerobic sludge fermentation was not significantly enriched with biohydrogen-producing microbial taxa. Heat pre-treated inoculum at a lower temperature of 50°C was enriched with non-spore-forming biohydrogen producers from Klebsiella, Escherichia and Citrobacter genera. These genera produced low biohydrogen yield by shifting the fermentation pathway to mixed-acid fermentation, producing a mixture of acetic and butyric acids and ethanol. The presence of non-biohydrogen producers, such as lactic acid bacteria also decreased biohydrogen production of the 50°C pre-treated inoculum, due to the lactic acid and ethanol fermentations. Heat pre-treatment at higher temperature of 100°C selectively enriched spore-forming microbial taxa. Among the species are biohydrogen producers B. coagulans, homoacetogens C. magnum, and non-biohydrogen producers from Bacillus species. These species re-direct the fermentation pathway to mixed-acid fermentation and produced high concentration of acetic acids. Methanogens, e.g. M. soehngenii present in the raw anaerobic sludge were suppressed in all the fermentation reactions. Metabolic functions analyses from the metagenome data showed that biohydrogen production potentially upregulate functions related to cellular processes (prokaryotic cell spore formation), carbohydrate metabolisms (sugar alcohols, monosaccharides, sugar acids and carboxylic acids metabolisms) and energy (fermentation and methanogenesis). In conclusion, inoculum heat pre-treatment is essential to enhance biohydrogen production using POME anaerobic sludge as heat pre-treatment enriched the inoculum with biohydrogen producers and suppress activities of methanogens, non-biohydrogen producers and homoacetogens

    Synthesis, characterization and fire retardancy of titania-based materials coated on wood

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    The number of fire cases in Malaysia has recently been increasing year after year, necessitating fire prevention measures. One prevention method is introducing fire retardant (FR) coating materials. FR coating material is a coating layer that works to prevent and reduce the probability of the material being flammable. Titania (TiO2) nanoparticles (NPs) and silica/titania (SiO2/TiO2) nanocomposites (NCs) worked as the FRs coating materials in this project, while rubberwood functioned as the flammable substrate material. The fire performance behaviour was then investigated using cone calorimeter, thermogravimetric analyzer (TGA), and flammability tests. According to the findings, FR coating of TiO2 NPs and SiO2/TiO2 (ratio of 0.1:1) NCs were able to increase the decomposition temperature (OD) of rubberwood by 41.32°C and 37.59°C, spontaneous ignition (SI) by 45.95°C and 32.6°C, and delayed ignition time (IT) by 79 s and 114 s. The results also proved the reduction in the intensity of fire (FI), heat release rate (HRR) by 43.32 kW/m2 and 45.87 kW/m2, rate of combustion (ROC) by 0.144 mm/s and 0.142 mm/s, mass loss rate (MLR) by 2.7 g/s and 2.9 g/s, and combustion efficiency (EHC) by 4.89 mJ/kg and 4.95 mJ/kg, respectively. The fuzzy logic system determined from these parameters that the HRR parameter should be considered as the key parameter that needs to be decreased in order to improve the FR performance of the TiO2-based materials. The physicochemical properties of TiO2-based materials coated on wood were then analyzed by various instruments and methods. Field emission scanning electron microscopy (FESEM) showed that the TiO2-based materials coated on the wood are spherical in shape, in the nano-range (25 to 40 nm), and agglomerated on the surface of the rubberwood. Meanwhile, energy dispersive X-ray (EDX) confirmed that the presence of titanium (Ti) and silica (Si) as the primary elements. The principal functional groups of TiO2 and SiO2 were also visible by fourier transform infrared (FTIR) spectroscopy. The X-ray diffraction patterns (XRD) demonstrated that the TiO2 in both TiO2 and SiO2/TiO2 samples are present in the anatase phase with a lower crystallinity, corresponding to the bandgap energies (3.2 eV and 3.4 eV) determined using diffuse reflectance ultraviolet-visible spectroscopy (UV-Vis). Through the peel adhesion test, it was proven that the application of 3-aminopropyltrimethoxysilane (APTMS) as a surface modifying agent allowed strong adhesion between the TiO2-based materials and wood and was uniformly coated. The wettability test showed that the surface of the rubberwood changed from superhydrophilic to hydrophilic. In conclusion, this study has demonstrated that TiO2 and SiO2/TiO2 (0.1:1) are the best coating materials on wood that can successfully operate as fire retardant materials, displaying the potential to decrease the performance of wood burning

    Estimating change point in multivariate processes via simultaneous mean vector and covariance matrix

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    In many industrial processes, several quality characteristics are inevitably related. In this situation, the mean vector and covariance matrix must be simultaneously monitored and controlled to determine whether a multivariate process is in control. With the increase in the number of variables, the performance of control charts is significantly reduced, and the time delay between the actual time of change in the process and the warning time of the control chart increases, which is one of the main challenges when using multivariable control charts. Between the real-time and the change time (called the change-point - CP), especially during the simultaneous monitoring and controlling of the parameters, the mean vector, and the covariance matrix cause problems such as delay or stoppage of the production lines or services, as well as inconsistent production of products or services. To improve this, a new way of estimating the CP will help statistical process control (SPC) professionals identify the cause(s) of out-of-control (OC) conditions, thus providing better feedback for process improvement. This study presented a new method based on an artificial neural network (ANN), which first examined the OC conditions for a multivariate process using the multivariate exponentially weighted moving average (MEWMA) and multivariate exponentially weighted mean square (MEWMS) control charts. Then, the ANN-fitting method was used to diagnose the cause(s) of OC conditions using the machine learning (ML)-classifier and estimating the length of delay time. Finally, the change point (CP) was estimated by integrating all these methods. The performance of the new approach was validated by comparing it with the results from another study. It also validated the proposed method developed by evaluating the accuracy and precision of this research. As a conclusion, the MEWMS chart was the best for detecting the OC condition while the support vector machines (SVM) gaussian model best to diagnoses the cause(s) o f the OC condition. The model provided has estimated the change point on one sample with difference over 10,000 tested cases (simulated) with a probability of 99%, which is an accurate and reliable model for a practical approach

    Investigation of silica nanoparticle-polymer hybrid stability under high temperature and salinity for oil displacement application

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    Polymer flooding is one of the most often utilised enhanced oil recovery (EOR) techniques because it provides excellent recovery. Polymer flooding enhances sweep efficiency and reduce viscous fingering severity by increasing fluid and oil mobility. Due to excellent viscosifying nature, and well-known physiochemical properties, partially hydrolyzed polyacrylamide (HPAM) is the polymer most often utilised for the application. However, high temperatures restrict its application because polymer will acts as shear-thinning, such it undergoes shear degradation and reduces viscosity at high shear rates and quickly destabilized and therefore unable to achieve the expected effects. High salinity also causes the molecular chain of the polymer to collapse, which results in a much smaller molecule and hence, produces a lower viscosity solution. Adding nanoparticle to polymer solutions is now required to alter their properties. Therefore, this study aims to investigate the effect of silicon dioxide nanoparticles (SiO2) addition to the stability of HPAM at high temperatures and salinity. The shear viscosity and the flooding performance at high temperature and high salinity gauge the stability of HPAM and the hybrid HPAM- SiO2. A series of stability measurements as well as core flooding experiment with variations of conditions were conducted in order to know the improvement offered by this nanoparticle towards HPAM polymer. At a temperature of 110 0C, the addition of 1 wt% SiO2 nanoparticle have enhanced the viscosity of 0.015 wt% HPAM, from 3.4 cP to 6.8 cP. This resulted in an almost 90% oil recovery rate. It also strengthened HPAM's salt tolerance at concentration of 5 wt% of NaCl by raising its viscosity up to 4.6 cP. This HPAM hybrid also have improve the oil recovery factor for this condition as well up to 85%. In conclusion, adding nanoparticles to HPAM will unquestionably increase the stability and potentially be used in EOR operations


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