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    Simulation of preventive and corrective maintenance schedule in reducing machine stoppage and downtime
    (2017-06)
    Tan, Sze Ming
    Maintenance approaches or strategies has been studied since many decades ago and nowadays it varies from the complex mathematical approach to improved and simplified yet effective time-based strategies. However, simulation of maintenance strategies is an intermittent field of research thus current maintenance strategies simulation model created a benchmark to imitate the methodology of implement maintenance strategies in real production. Currently, the major drawback of most of the published researchers is in the application of only single machine, single maintenance strategies or multiple machines of the same type working in parallel which does not reflect the real and complex manufacturing system. Thus, this project is conducted to create a model of maintenance strategies integrated with a dynamic manufacturing system. The system consists of five different machines and each cycle time of machines differ considering the shift time of maintenance team and spare part availability. The work has been conducted using WITNESS 14 Manufacturing Performance Edition software. The model was developed to imitate a Surface Mounted Technology (SMT) production system by considering the changeover time, minor and major breakdown, corrective maintenance (CM) as well as preventive maintenance (PM) scheduling. The aim is to study the effect of maintenance strategies towards the machine downtime. The SMT line was simulated and evaluated based on the availability of individual machines via discrete event simulation system. Presuming that each machine has different degradation level, which follows a Weibull distribution, the maintenance scheduling strategies were planned based on First Come First Serve (FCFS) basis if the same type of maintenance strategies is due on different machines but prior to CM. The findings of this project demonstrated that a daily PM schedule can improve the system availability by 30% while increasing the availability of machine up to 90%.
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    Photocatalytic Degradation Of Phenol By Silica Gel-Supported Titania Nanotubes
    (2012)
    Wong, Chung Leng
    TiO2 nanotubes and immobilized TiO2 nanotubes were successfully synthesized by a hydrothermal method and binding method. The produced photocatalysts were characterized by the Brunauer-Emmett-Teller (BET) method, scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), transmission electron microscope (TEM) and X-ray diffraction (XRD). The photocatalytic activities of the photocatalysts were evaluated through the photocatalytic degradation of aqueous phenol solution in a batch reactor. TiO2 nanotubes produced at 130 °C for 3 h showed the highest degradation rate of phenol compared with the other samples prepared at 130 °C for 1 h, 5 h and 7 h, complete degradation being achieved in 130 min. Special focus was given in order to determine the optimum composition of each component (catalyst, support and binder) in the immobilization of TiO2 nanotubes. The highest efficiency of phenol degradation was achieved when the ratios of TiO2 nanotubes: silica gel: colloidal silica was 1:2:20. For the comparison, TiO2 nanotubes and immobilized TiO2 nanotubes showed higher photocatalytic activity as compared with pure TiO2. The photocatalytic performance of TiO2 nanotubes and immobilized TiO2 nanotubes achieved 100 % and 98.0 % respectively, of phenol degradation, whereas pure TiO2 attained only 77.0 % degradation. The photocatalytic activity of the immobilized TiO2 nanotubes was slightly decreased after four cycles for phenol degradation. The loss in percentage of photocatalytic degradation was less than 2 % even after four cycles. The results for the studied operating parameters were: the presence of the anions were found to inhibit the photocatalytic degradation of phenol in the order of SO4 2- > Cl- > HCO3 -; the optimal medium pH was found to be pH 5.5 (natural pH); the air flow rate gave an optimum value of 0.3 L/min; the phenol degradation efficiency decreased as initial phenol concentration increased. Response surface methodology (RSM) based on the central composite design (CCD) was used to optimize and predict the interactions between process variables by reducing the numbers and the times for the experimental runs. Finally, the reaction kinetics of phenol degradation by the immobilized TiO2 nanotubes obeyed well with the Langmuir-Hinshelwood model. The values of the reaction rate constant, k and the adsorption constant, K obtained were found to be 0.9324 mg/L.min and 0.0121 L/mg, respectively.
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    Evaluation Of Salmonella Typhi Antigens Hlye And Ynce For The Detection Of Typhoid Fever And Its Carriers
    (Universiti Sains Malaysia, 2019-06)
    Anthony Joseph, Freddy Franklin
    Salmonella Typhi (S. Typhi) is the causative agent of typhoid fever (TF) that causes millions of infections and 1% of mortality worldwide. TF is highly endemic in Southeast Asia and sub-Saharan Africa. Certain individuals with TF may not recover fully and can become carriers that do not show any symptoms of the disease. The carriers can then spread the disease when they come into contact with food and water. Antibodies against S. Typhi HlyE are elevated among patients with TF compared to healthy individuals, while antibodies against YncE were reported to be elevated among carriers of S. Typhi. Rapid and accurate methods to diagnose individuals with TF or who are carriers are crucial to manage the disease. In this study, recombinant HlyE and YncE antigens were found to be useful for the identification of individuals with TF and those who are possible carriers. Firstly, recombinant HlyE and YncE were expressed and purified. Next, rHlyE and rYncE ELISAs were developed to enable quantitative screening of many samples simultaneously to identify those with elevated IgM, IgG and IgA antibodies against the antigen. A total of 425 serum samples (acute typhoid patients, carriers, food handlers, other febrile, and healthy individuals) were screened with the ELISAs.The rHlyE-IgG, -IgA and -IgM ELISAs demonstrated a sensitivity of 70%, 80% and 11% respectively to detect acute typhoid patients, and with a combined sensitivity of 83%.The rYncE ELISA identified 16 possible carriers based on their antibody profiles. Taken together, this study showed that HlyE antigen could be used to identify individuals with TF while the YncE antigen may be used to identify possible carriers, but further validation is required.
  • Publication
    Factors Affecting The Use Of Gamification In Online Learning Environment Among School Teachers In The Kingdom Of Saudi Arabia
    (2023-05)
    Ayed S, Alosaimi Mutlaq
    The use of technology and e-learning systems in classrooms can have a significant impact on students’ learning. Not to be left behind, the Saudi government launched the ‘Future Gate’ project to implement technology in secondary schools in which gamification is applied in this e-learning platform. However, what are the factors that might influence its acceptance and utilization among the school teachers? Specifically, this study examined the effects of performance expectancy, effort expectancy, social influence, hedonic motivation, facilitating conditions, and habit on teachers’ behavioural intention to use gamification in teaching and learning activities in the Future Gate platform. It also investigated the impact of age, gender, and experience on these variables. In addition, the study evaluated the effects of task and technology characteristics and how they influence teachers’ perception of Task-Technology Fit (TTF) and the teachers’ behavioural intention to use gamification. This study utilised SEM-Partial Least Square (PLS-SEM) to analyse the relationships between the constructs identified from the literature review. A total of 328 secondary school teachers participated in this study from seven districts in Saudi Arabia.
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    Nurses' knowledge and practice regarding prevention of surgical site infection (SSI) in Hospital Universiti Sains Malaysia (USM)
    (Pusat Pengajian Sains Perubatan, Universiti Sains Malaysia, 2021-06)
    Aktar, Nurul Eiman Danisyah
    Surgical site infection is an infection that occur 30 days after surgery and cause many effects such as increasing risk of death, increasing hospital stay and financial constraints for patient and health care system. A cross sectional study has been conducted to determine nurses’ knowledge and practice regarding prevention of SSI in Hospital USM. This study also examined the difference of knowledge and practice between general surgery and orthopaedic nurses. Pearson Chi-square was used to determine the association between clinical working experience with knowledge and practice towards prevention of SSI. A total of 66 nurses, 34 nurses were from surgical and 32 nurses from orthopaedic wards were recruited through proportional sampling. Data were collected September 2019 until June 2020 using self-administered questionnaires and analysed using SPSS version 26.0 for Window. Ethical approval was obtained from Human Research Ethics Committee (HREC), Universiti Sains Malaysia. The mean age of the participants was 31 years old. The results revealed staff nurses were having poor knowledge level (M=16.18, SD= 2.745) regarding prevention of SSI. Meanwhile for level of practice, nurses were found to be having good practice towards prevention of SSI (M=67.82, SD=6.44). There was no significant difference in knowledge between general surgery and orthopaedic nurses (p=0.467). While, there was significant difference in practice between general surgery and orthopaedic nurses (p=0.013). There was no association to be found between clinical working experience with knowledge (p=0.834) and practice (p=0.197) regarding prevention of SSI. It showed that nurses need more exposure towards SSI and its prevention for them to identify, assess and implementing the correct practice. As a conclusion, it is shown that knowledge and practice towards SSI is important as the results shows that nurses in Hospital USM had insufficient knowledge. A workshop or course training should be implemented to enhance their knowledge.