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Numerical solution of partial differential equations for lid-driven fluid flow and heat transfer analysis with no-slip and free-slip effects / Wong Hon Fei
Get PDFThermal fluid is a branch of science and engineering that covers the application of experimental research and mathematical modeling based on fundamental laws from physics, heat transfer and fluid dynamics. The great significance of thermal fluids can be seen in phase transition and chemical reactions. Perhaps two-dimensional lid-driven model is the simplest model to demonstrate the study of the thermal fluids. The behavior of fluid that filled inside the lid-driven cavity when subject to different boundary conditions (free-slip and no-slip), different aspect ratios and different steady-state criteria are studied extensively. The partial differential equations of time-dependent vorticity-stream function and thermal energy equation are discretized and solved using finite difference method. All the codes were written and solved inside Matlab® environment and the results were verified using commercial engineering simulation software named Ansys Fluent®. For the first study, an analysis of time dependent stream-function of fluid to identify patterns of forming, merging and unmerging of additional eddy is presented when steady-state condition with different criteria are achieved. Due to numerical error, it is also observed that the value of stream function begins to drop and streamline distribution changes shape after achieving steady-state criterion of . Also, damage of merging and formation of additional eddy happens until the free-slip boundary condition effect passes the threshold value. For the second study, the iteration process focuses on dissipation of viscous-heating through a transient conduction process of the entire liquid filled inside the lid-driven 6 10 e cavity. The time–dependent fluid flow and heat transfer with viscous heating process are depicted by contour plot and image plot inside Matlab® environment. For the third study, Robin boundary condition is adopted rather than Neumann boundary condition which employed in the second study. Moreover, heat transfer analysis is extended to cooling process in the third study. The effects of viscous heating coupled with several other physical parameters, namely Reynolds, Prandtl, Peclet and other numbers are examined. Finally, a simple graphical user interface is developed using Matlab® to facilitate the end user in analyzing the fluid flow
Synthesis of rhodamine chemosensors with high selectivity and sensitivity for multiple metal ions detection / Nur Amira Solehah Pungut
No full textFour rhodamine B based chemosensors have been synthesized through condensation reaction between rhodamine B hydrazide with 2-hydroxy-3-methoxybenzaldehyde (RBOV), fluorene-2-carboxaldehyde (RFC), trans-4-(Diethylamino)cinnamaldehyde (RT4) and 3,4,5-trimethoxybenzaldehyde (R3). The compounds were characterized by FTIR, 1H NMR, 13C NMR, mass spectroscopy, and single crystal x-ray diffraction. These chemosensors exhibit different and unique properties as RBOV can detect Cu2+, Ni2+ and Co2+ ions, RFC is able to detect Al3+ and Cu2+ ions, RT4 detects Cu2+ and Fe3+ ions and R3 is able to detect Fe3+ ions only. The detection of these metal ions was further investigated using UV-vis and fluorescence spectroscopy. For all sensors, a 1:1 binding stoichiometry of the chemosensors-metal ions were determined through Job’s plot analysis while the detection limit (in μM) of the chemosensors were determined from the UV-vis and fluorescence titration experiments. Furthermore, the binding of the
chemosensors with the metal ions were also illustrated by the partial FTIR and 1H NMR spectrum. In determining the potential application of the sensors both biologically and environmentally, reversibility, test strips and MTT assays have been successfully prepared and studied
Effect of high purity rice husk silica synthesised using solvent thermal treatment method on the properties of natural rubber compounds / Zainathul Akhmar Salim Abdul Salim
No full textIn recent years, research on bio-based materials, such as rice husk is steadily gaining momentum. Despite their huge developmental potential, rice husks are often left unutilised following the harvesting season, wasting a natural wealth that could be explored. Their high silica content makes them potential fillers to replace commercial precipitated silica (PS) in the rubber industry. For first series, highly pure silica with small particle size and high surface area was extracted from rice husks via solvent-thermal treatment, followed by leaching with different concentrations of hydrochloric acid (HCl). This treatment method was modified from TAPPI T204 (2007) and TAPPI T264 (1997) standards, which are used for wood extraction in the pulp and papermaking industry. For second series, characterisation on treated rice husk silica (RHS) was conducted. RHS that was leached with 1.0 M HCl recorded the highest particle purity with 99.99% of SiO2 content and the highest BET surface area of 234.25 m2/g compared with RHS leached with 0.01 M, 0.1 M, 2.0 M, and 3.0 M HCl. All RHS samples were in the amorphous state following incineration at 700°C for 4 hours. For third series, RHS sample with the highest purity was incorporated in NR compounds at 2, 4, 6, 8, and 10 parts per hundred rubber (phr). Even without surface modification, the RHS-filled NR compounds showed improvements in strength-related properties at the optimum loading of 4 phr. The thermal stability of the NR compounds had also improved with RHS addition. The properties of the RHS-filled NR compounds were further enhanced following RHS surface modification with silane coupling agents. Surface modification is vital to improve the compatibility between the hydrophilic RHS and the hydrophobic NR by making RHS hydrophobic, which reduced the filler-filler interaction. This transformation had also increased the cure rate of the rubber compounds because the silane-modified RHS stopped reacting with cure activators and accelerators, consequently increasing the cure efficiency. In fourth series, three types of silane coupling agents with different functional groups, which are namely; bis[3-(triethoxysilyl)propyl]tetrasulfide (TESPT), (3-mercaptopropyl)trimethoxysilane (MPS), and (3-aminopropyl)triethoxysilane (APTES) were used to modify RHS surface. The modified RHS samples were incorporated in NR at the optimum loading of 4 phr. The increased reinforcing efficiency due to the strong rubber-filler interaction greatly improved the mechanical, thermal, and dynamic mechanical properties of all silane-modified RHS-filled NR compounds. However, TESPT led to the most outstanding performance of the RHS-filled NR compound compared with the other two alkoxy-based silanes, in terms of cure characteristics, overall strength-related properties and thermal stabilities. In fifth series, the effectiveness of RHS as a filler was compared to PS. Both types of silica were modified with TESPT and incorporated in NR at 4 phr loading. The performance of RHS as a filler was equivalent to PS in most properties. This shows that RHS synthesised using the solvent-thermal treatment method is suitable to be used as NR filler
Graphical user interface test case generation for android apps using Q-learning / Husam N. S. Yasin
No full textSoftware testing is an effective means for assuring the quality of applications. Android applications (or mobile apps) have become an essential part of our daily life. Statistics affirm that 85% of smartphones worldwide are Android-based. Unfortunately, 17% of Android apps are still considered low-quality apps due to app crashes that can be avoided through intensive and extensive testing. Recently, Graphical User Interface (GUI) testing of Android app has gained considerable interest from the industries and research community due to its excellent capability to verify the operational requirements of GUI components. In the related literature, GUI test generation tools focus on generating tests and exploring app functions using different approaches. These tools are used to make the testing process more effective by finding faults; more comprehensive by achieving better code coverage and faster by producing the smallest possible event sequences. However, a common limitation of these tools is the low code coverage because of the tools' inability to find the right combination of actions that can drive the application into new and important states. Exploring the app's state extensively requires long event sequences to find the correct combination of actions, leading to excessively long transitions and wasted time. Such tools must choose not only which user interface element to interact with, but also which type of action to be performed to increase the percentage of code coverage and to detect faults with a limited time budget. This research addresses the problem of generating an effective test for Android apps that maximizes the instruction, method, and activity coverage by minimizing redundant execution of events. Hence, it proposes a Q-Learning-based test coverage approach developed in DroidbotX to generate GUI test cases for Android apps. It is a fully automated black-box testing approach that uses Upper Confidence Bound (UCB) exploration-exploitation strategy to generate actions that visit unexplored states of the app and uses the execution of the app on the generated actions to construct a state-transition model. Instead of randomly selecting the inputs, the test generator learns how to act in an optimal way that explores new states by using new actions to gain more rewards. Thus, the never selected actions can present a higher reward when compared to already executed actions. This reduces the redundant execution of events and increases coverage. The overall performance of DroidbotX was compared to five state-of-the-art test generation tools on 30 Android apps. DroidbotX achieved 51.5% accuracy for instruction coverage, 57% for method coverage, and 86.5% for activity coverage. It triggered 18 crashes within the time limit and shortest event sequence length compared to the other tools. The results demonstrate that the adaptation of Q-Learning with UCB exploration can significantly improve the effectiveness of the generated test cases. The computation time complexity of the Q-Learning-based test coverage algorithm was also analyzed. The results showed that time complexity was reduced significantly fro
The effect of technical factors on acceptance of using mobile learning: An extended model / Saud Saleh Alghazi
No full textThere is no doubt that mobile devices such as smartphones have become an important tool in the higher education domain. Even though the features and functions of these devices help learners in performing their learning activities, the usage of these devices for learning remains relatively limited amongst students. The low usage of these devices in learning field could be attributed to several reasons relating to technical or non-technical issues. Many acceptance models were developed to measure factors affecting usage of technology, as well as mobile learning. However, limited studies discussed the advantages of the technical aspects, such as device performance, connectivity, processing power, and memory of imparting knowledge through mobile learning. Therefore, there is a need to investigate these limitations of using mobile devices in education to understand the factors that could improve students' usage of these devices for mobile learning in higher education. In order to achieve this outcome, this study aimed to propose a model for measuring the acceptance of mobile learning that emphasises on technical factors to determine the main factors that influence the use of mobile learning by students. New technical factors were proposed, such as Device Compatibility, Device Connectivity, Device Memory Capacities, Device Performance, Device Processing Power, Security and Reliability of Mobile Learning on Device, Network Coverage, and Network Speed. These factors were used to extend The Unified Theory of Acceptance and Use of Technology model for a better understanding of students’ acceptance of mobile learning. Structural equation modelling was employed to analyse data collected from 612 students to verify the validity of the proposed model. The results indicated that factors such as Device Compatibility, Device Connectivity, Device Memory Capacities, Device Performance, Network Coverage and Network Speed have a significant and positive influence on the intention of students to use mobile learning. A guideline is proposed based on the proposed model. This research presents important recommendations for decision-makers and developers on understanding the needs of students in adopting M-learning effectively as a useful learning tool
Hadith berkaitan penyakit al-'Ayn: Analisis hubungannya dengan pukau dan pemahaman dalam kalangan masyarakat Malaysia / Mohamad Khairul Faiz Mohd Khadzali
No full textEvil Eye is a type of act that is associated with pukau. There was no prominent debate
among the Malaysian community about the evil eye, but discussions and cases of
poaching took place through reports from news, newspapers and social media.
Furthermore, the explanation of the evil eye among Islamic medical practitioners is also
unclear, and some are even confused about the actual understanding by associating it
with pukau. This study aims to explain from the point of view of the true understanding
of the evil eye from the fiqh al-hadith angel and explains its relationship with pukau as
well as analyses the understanding of Malaysian society between the two. Through
quantitative analysis, a total of 458 respondents were involved in answering the
questionnaire as a research instrument. The questionnaire contained 36 items using
Likert scale measurements. The reliability value of the study instrument is 0.87. The
data were analysed by using Statistical Package for the Social Science (SPSS) version
22.0. The results of the study found that the evil eye and pukau are two different things
in which the evil eye is something that affects the soul of its victim so as to bring harm
to its victim due to jealousy and amazement. While pukau is a magic practice that uses
the help of jinn to influence the human mind through touch, sight, smoke and so on.
From the analysis of hadith from al-Kutub al-Sittah, there are 43 hadiths that discuss the
evil eye, which can be divided into 11 themes, and it can be concluded that the fact of
the evil eye is real and there are certain treatment methods of the Prophet SAW in
treating the disease of al- 'Ayn. However, as a whole, there is no direct relationship of
evil eye with pukau except in few aspects. Among the aspects are, firstly, both can be in
effect without the use of the eye. Secondly, both affect human souls and as a result
harms the victim. Thirdly, one of the reasons that the victim might be chosen or random
is due to displaying the prosperities possessed through the social media as well as to the
public. From the field study, it was found that the understanding of the community is at
a moderate level because out of 36 items from questionnaire posed only 20 the majority
answered correctly. Thus, in the view of the researchers, the community still do not
fully understand about the evil eye, which may be unusual in society, but they know and
understand about pukau
Electronic properties of DNA from selected Pleurotus species using DNA specific schottky diodes/ Nastaran Rizan
No full textThe exciting discovery of the semiconducting-like properties of deoxyribonucleic acid (DNA) and its potential applications in molecular genetics and diagnostics in recent times has resulted in a paradigm shift in biophysics research. In this aspect, recent studies are being conducted towards detecting charge transfer mechanism to understand the electronic properties of DNA based on its sequence-specific electronic response. This current research aims to contribute towards this effort by fabricating and developing DNA-specific Schottky barrier diodes for characterizing and identifying mushrooms using current-voltage (I-V) profiles. Selected electronic properties such as ideality factor, barrier height, shunt resistance, series resistance, turn-on voltage, knee-voltage, breakdown voltage and breakdown current were calculated. The data was further utilized to quantify the identification process as compared to conventional morphological and molecular characterization techniques. Conventional techniques are used in order to study biodiversity, but sometimes it can be misleading and unreliable and is not sufficiently useful for the identification of mushrooms genera especially for identification of closely related species in genus Pleurotus. In this research, genomic DNA as well as amplified specific regions (internal transcribed spacer, large subunit ribosomal DNA and large subunit of ribosomal polymerase II) of selected species of Pleurotus were subjected to IVmeasurements. Both genomic and amplified DNA showed distinct profiles corresponding to each species. However, comparison of I-V profiles of genomic and amplified DNA suggested that genomic DNA is a better choice for electronic identification of species. This is mainly due to more base pair differences between genomic DNA of different species. High similarity in the conserved regions showed a closer yet distinguishable electronic profile for each species. The electronic profiles, both in the negative and positive bias regions were however found to be highly characteristic according to the base-pair sequences. However, DNA charge transfer are significantly regulated by pH fluctuations which influences the stability of the double helix structure
and strongly attenuated its electronic profile. To investigate the pH influence, genomic DNAs integrated within an aluminium (Al)-indium tin oxide (ITO) Schottky junction was prepared and its electronic profiles studied. Although DNA is known to be reasonably stable in aqueous solution, environmental factors can also affect the helical structure resulting in significantly attenuated electronic profiles. DNA molecules are not stable when stored for long periods in solution form at room temperature (RT) prompting much interests for solvents in which DNA structures exhibit long-term stability. Ionic liquid
(IL), 1-butyl-3-methylimidazolium acetate ([BMIM][Ace]) is a potential solvent that ensure long-term stability of DNA. Therefore, the effect of IL on genomic DNAs was investigated by using the I-V profiles. Furthermore, various solid-state parameters calculated allow us to understand the charge transfer mechanism in DNA molecules as a function of pH conditions and IL, which could act as a potential indicator for various stages of DNA functionality
A theoretical framework for the adoption of cloud computing in hospital information systems /Shady Gomaa Abdulaziz
No full textCloud Computing (CC) is becoming a favourable trend in managing digital data. However, there is a low CC adoption rate in Health-Care Institutions (HCIs) than in other industries due to many reasons like awareness, staff, and costs. This research aims to: (1) investigate the CC adoption in the Saudi Health-Care Institutions (SHCIs), (2) determine the factors that influence the CC adoption in selected SHCIs, (3) develop a theoretical framework for the deployment of CC adoption in selected HCIs based on factors determined earlier, and (4) validate a research framework for the adoption of CC in SHCIs. The purpose of this study is to determine the factors influencing CC adoption in SHCIs. The constructs used to develop a theoretical framework for deployment CC in SHCIs. Data were collected by a purposive sample of (230) health-care staff for three public hospitals in the Kingdom of Saudi Arabia (KSA) as a case study. Two hundred (200) research participants contributed extensively in answering the questionnaire and participated in assessing the improvised method; also, the researcher observations were employed. The data analysis was performed based on the Statistical Package for the Social Sciences (SPSS) to interpret the statistics for data analyses and regression. Besides, the structured equation modelling technique (SEM) using the partial least squares (Plsek & Greenhalgh, 2001) path modelling method was used to assess correlations between the developed framework themes of CC adoption in SHCIs as the independent variable with the intention to adopt CC as the dependent variable. Moreover, a thematic approach to the analysis was applied to allow the researcher to report the study observation findings. The findings of this study indicated that Compatibility, Complexity, IT Infrastructure Readiness, Relative Advantage, Sharing & Collaboration, Security and Privacy, Technology Readiness, Trust, Government Support, Regulatory Concerns, External Support, Mobile Access, Soft Financial, Perceived Ease of Use are the significant factors affect CC adoption in SHCIs. Finally, this research's findings based on observational data indicated limited use of the intent of technology adoption HIS based-on CC. Factors that serve as barriers to implementing and accepting technology include the staff's capacity and expertise, management issues, resources, community, technological issues, environmental issues, rules of operation, insufficient infrastructure, and language issues. This research's findings can also guide future empirical research into the factors that affect CC adoption in the health-care context
A study of copper oxide-zirconia produced by conventional and pressureless two-step sintering process / Alexander Chee Hon Cheong
No full textIn the thesis, the effect of adding transition metal oxide (CuO) on the sintering behavior of 3 mol% Y-TZP was systematically investigated. The CuO dopant, ranging from 0.05 wt% to 1 wt%, were attrition milled with the base Y-TZP powders to obtain the CuO-doped Y-TZP. The first phase of the research investigated the effect of conventional single-step sintering (SSS) cycle, performed over the temperature range of 1250 to 1500 C, was carried out in order to understand the influence of CuO on the properties of Y-TZP. The second phase of the work involved the use of pressureless two-step sintering (TSS) cycle to promoted densification without inducing grain coarsening in the CuO-doped Y-TZP and to elucidate the sintering mechanism. The study revealed that for the SSS scheme, the addition of up to 0.2 wt% CuO dopant was most effective in enhancing the densification and mechanical properties of the Y-TZP in particularly at low temperatures below 1350 oC. The phase analysis revealed that the tetragonal phase was disrupted as evident from the monoclinic phase formation as the CuO amounts exceeding 0.2 wt%. In particular, the 1 wt% CuO addition was detrimental and samples exhibited high porosity and low mechanical properties. However, in all cases, the development of the cubic phase was not observed in the present work. The role of CuO has been explained and associated with mechanism involving the reaction with yttria stabilizer forming a transient liquid phase during sintering. The research also demonstrated that the fracture toughness of the Y-TZP was governed by a grain size limit which varied depending on the amount of doping levels. In addition, the Vickers hardness was found to increased linearly with the bulk density. Nevertheless, the study revealed that compared to the undoped Y-TZP, the addition of 0.2 wt% CuO resulted in enhanced hardness and finer grain sizes when sintered at relatively low temperatures. In the TSS cycle, the results confirmed that efficacy of this scheme in aiding densification of CuO-doped Y-TZP without inducing grain coarsening. The beneficial effects of TSS in enhancing the Vickers hardness and fracture toughness of tetragonal zirconia when compared to SSS, without incurring grain growth have been demonstrated. This feature of TSS which allows for the inhibition of grain boundary migration and the activation of grain boundary diffusion at lower dwelling temperature during sintering were responsible for the enhancement of the mechanical properties of tetragonal zirconia
A STEM game based learning apps model to enhance creativity among preschoolers / Najmeh Behnamnia
No full textAlthough recent digital game-based learning studies have shown the possibility of creating new forms of learning and teaching, it is not clear how Digital Game-Based Learning (DGBL) applications can affect creativity and learning on young children. Hence, the main purpose of this thesis is to investigate whether DGBL technology (tablet and smartphone) can improve creativity and learning skills among children aged between 3 and 6. Thus, this thesis has reviewed the literature based on Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) principles. The results of the literature review showed that DGBL potentially affects students' ability to develop creative skills and critical thinking, knowledge transfer, acquisition of digital skills and experience, and a positive attitude toward learning. Then, the first experiment of this thesis examined which components of creativity based on the “Analyzing Children's Creative Thinking” (ACCT) framework of games can affect the level of learning in preschool children. According to the components found in creativity development from the first experiment, this research presented a single model of Science, Technology, Engineering & Mathematics (STEM)-based learning application to prove to enhance the learning of preschool children in the second experiment. In addition, in this thesis, a simple DGBL application has been designed and implemented to evaluate the model. The results show that the components of creativity can have a significant impact on the level of learning mathematics and in the next step positively affect science and engineering for preschool children. This thesis provides recommendations and suggestions on how to increase creative skills for motivating and improving learning outcomes in digital STEM games-based learning at the preschool level