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Heat transfer to nanofluids in closed conduits flow / Thenarasu Pakiyanathan
No full textDifferent nanoparticles were synthesized and covalenty or non-covalently functionalized to disperse the nanoparticles properly in different base fluids. Thermo physical properties of the nanofluids were measured in different equipment and the nanofluids were characterized. Heat transfer coefficient, friction losses were analyzed with the variation of concentrations, particle characters, particle types etc. Heat transfer and friction loss properties were then correlated with the particle characters and the variable physical and thermal properties of the nanofluids. Experimental and numerical results were compared for validation of the data and application as reference. The common working fluid in a heat exchanger can be identified as oil, water and ethylene glycerol etc. These fluids exhibit advantages in terms of ease of handling, recycling and disposing. Besides that, it has a low market price. Despite the advantages listed, these
fluids exhibited low thermal properties. Moreover, characteristic such as fouling and low total surface energy makes the overall heat transfer performance low resulting in the design of heat exchanger to be larger so that the desired energy can be harnessed for the operations in the time duration.
Nanofluid has been identified as a substitute to water and oil as a working fluid in the heat exchanger. There were attempts to incorporate it into the industry. At turbulent fully developed flow in annular passage for TiO2+SiO2/DW and GAGO/DW nanofluids, the friction factor, pressure drops, heat transfer coefficient and Nusselt number at constant heat flux boundary condition were evaluated. The outcomes of the experimental data were compared with those of the base fluids. However, the current findings shown the improved heat exchanger fluids as the nanofluids. They have improved thermo-physical characteristics and heat transfer enhancement, such as about 200 percent improvement in heat transfer coefficient at a low nanoparticle concentration of 0.1wt percent. There was not much extra frictional pressure drop at such a low concentration of nanofluids. Thus
the new and environmentally friendly TiO2+SiO2/DW and GAGO/DW nanofluids could be used as highly effective working fluids in a variety of heat transfer applications and specially in the situations when a high heat transfer rate is require
A cross sectional study on resilience and coping strategies among medical officers during the Covid-19 pandemic and it's association with depression and anxiety / Rahul Yong Wern Kean
No full textIntroduction: The mental well-being of medical officers during the Covid-19 pandemic is
becoming an increasing concern. The on-going pandemic has drastically increased work
demands for doctors and this resulted in high levels of stress, depression and burnout
among medical officers.
Objectives: This study aims to determine the patterns of resilience and coping strategies of
front-line medical officers during the Covid-19 pandemic, as well as their association with
depression and anxiety.
Study design: This is a single center, cross sectional study on Covid-19 front-line medical
officers posted in medical wards in Hospital Tuanku Ja’afar, Seremban. The instruments
used were a sociodemographic questionnaire, Brief Resilience Scale (BRS), Brief COPE,
Coronavirus Anxiety Scale (CAS), and Hospital Anxiety and Depression Scale (HADS).
Data was collected over a six-month period from February 2021 to July 2021. Statistical
data analysis done using the Statistical Package for the Social Sciences (SPSS) version
28.0. included using a Pearson Chi-square test to investigate the association between
categorical explanatory variables (sociodemographic, medical conditions, and job-related)
with the categorical anxiety and depression symptoms. Continuous variables were tested
with a t-test, or Mann-Whitney against the outcome variables, depending on the normality
of the data. A multiple logistic regression analysis was carried out using “Enter” method to
analyse all factors with a p-value < 0.05 in association with anxiety and depression
symptoms among medical officers.
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Results: A total of 140 front line medical officers from Covid-19 wards participated in this
study, with the majority being female (69.3), Malay (60%), single (61%), from medical
department (53.6%) and on average had three months duration of posting in Covid-19
wards. The prevalence of symptoms of anxiety and depression was 45.0% and 24.3%
respectively. The majority of the participants had normal to high resilience (79.3%) with
the average score of resilience being 3.25. Low levels of resilience were significantly
associated with depression (p = 0.018, aOR (95%CI) 0.292 (0.105-0.808). Among problem�based coping strategies, the use of informational support and planning were associated with
anxiety symptoms (p=0.001). Among emotion-focused coping strategies, those that were
associated with anxiety symptoms were emotional support (p=0.002), venting (p<0.001),
humor (p<0.001), acceptance (p=0.014), and self-blame (p<0.001). As for avoidance
coping strategy, three out of four sub-components, notably self-distraction (p<0.001),
denial (p=0.001), and behavioral disengagement (p < 0.001), were correlated with anxiety
symptoms. After multiple logistic regression analysis, only venting (p=0.028, aOR
(95%CI) 1.556 (1.049-2.308)) and behavioral disengagement (p=0.016, aOR (95% CI)
1.607 (1.092-2.365)) were associated with anxiety symptoms. Emotion based coping
strategies venting (p=0.022) and humor (p<0.001), self-blame (p=0.006), and avoidance
coping strategies denial(p<0.001) and behavioral disengagement (0.001) were associated
with depressive symptoms. After multiple logistic regression analysis was done, only lower
resilience (p=0.018, aOR(95% CI) 0.292 (0.105-.808)) and humor (p=0.004, aOR (95%
CI) 1.506 (1.140-1.991)) were associated with depressive symptoms.
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Multiple logistic regression analysis reported no significant association with
sociodemographic factors such as age, gender, number of children, previous posting with
depression or anxiety among front-line medical officers.
Conclusion: The prevalence of anxiety and depression is high among front-line medical
officers. The overall good levels of resilience among medical officers are protective against
depression. Remedial steps should be taken to preserve psychological well-being among
front-line medical officers
Penyampaian perkhidmatan jaringan perlindungan sosial dalam kalangan warga emas / Puteh Soraya A. Rahman
No full textTesis ini merupakan satu kajian tentang penyampaian perkhidmatan jaringan perlindungan sosial kepada populasi terpinggir iaitu warga emas miskin / miskin tegar tegar sebatang kara (WEMTSK) di Malaysia. Kajian ini dijalankan bagi mengenalpasti faktor-faktor yang menghalang kumpulan sasar iaitu warga emas miskin / miskin tegar sebatang kara daripada menerima perkhidmatan dan bantuan program jaringan perlindungan sosial. Kajian ini telah menyelidik isu-isu yang membelenggu kecekapan penyampaian perkhidmatan awam ini. Sesi temubual secara mendalam kepada kumpulan sasar dan para pegawai perancang, penyelaras, pelaksana, dan pemantau program jaringan perlindungan sosial sama ada di peringkat pusat, negeri, dan daerah telah dilakukan bagi mengupas isu tersebut, serta meneliti faktor penghalang keberkesanan usaha penyampaian perkhidmatan. Dapatan daripada sesi temubual ini telah dibanding dengan elemen yang terkandung dalam The SERVICE Framework: A Public-service-dominant Approach for Sustainable Public Services yang diketengahkan dalam revolusi pentadbiran awam New Public Governance bagi menentukan kecekapan dan kelestarian sesebuah organisasi perkhidmatan awam. Hasil kajian ini menunjukkan bahawa terdapat empat cabaran utama yang mempengaruhi penyampaian perkhidmatan jaringan perlindungan sosial kepada warga emas miskin / miskin tegar sebatang kara di Malaysia, iaitu (a) cabaran tadbir urus, (b) cabaran kumpulan sasar, (c) cabaran penyelarasan bantuan, dan (d) cabaran pengurusan data. Keempat-empat cabaran ini memerlukan penambahbaikan terutamanya daripada segi komitmen pegawai dan pemimpin tempatan, analisis mikro keperluan kumpulan sasar, penyelarasan pelaksanaan program, dan analitik data raya bagi meningkatkan keberkesanan dan kecekapan penyampaian perkhidmatan awam pada masa hadapan
Synthesis, characterization and evaluation of new piperazinium/dipiperidinium dicationic-based molten salts and ionic liquids as catalysts for some organic reactions / Lia Zaharani
No full textThe new ionic liquids and molten salts including 4,4’-trimethylene-N,N’-dipiperidinium sulfate [TMDPH2]2+[SO4]2-, 4,4’-trimethylene-N,N’-dipiperidinium chlorosulfonate [TMDPH2]2+2[ClSO3]-, 1H,4H-piperazine-diium dichlorosulfonate [PZH2]2+2[ClSO3]- were designed and synthesized. The chemical structure elucidation of these ionic liquids and molten salts was performed by 1D NMR, FTIR, and mass spectra. Then, the correct structure was elucidated by COSY experiment and Raman spectroscopy. Some physical properties, thermal behavior, and thermal stability of these ionic liquids and molten salts were determined and reported. The formation of a two-protonic acid salt namely 4,4’-trimethylene-N,N’-dipiperidinium sulfate [TMDPH2]2+[SO4]2-, instead of namely 4,4’-trimethylene-N,N’-dipiperidinium hydrogensulfate was evidenced by NMR analyses. The catalytic of this ionic liquid was demonstrated in the esterification reaction of n-butanol and glacial acetic acid under different conditions. The desired acetate was obtained in 62-88% yield without using a Dean-stark apparatus under optimal conditions. α-Tocopherol (α-TCP), a highly efficient form of vitamin E, was also treated with glacial acetic acid in the presence of the ionic liquid, and O-acetyl-α-tocopherol (Ac-TCP) was obtained in 88.4% yield. The formation of 4,4’-trimethylene-N,N’-dipiperidinium chlorosulfonate [TMDPH2]2+2[ClSO3]- and 1H,4H-piperazine-diium dichlorosulfonate [PZH2]2+2[ClSO3]- was indicated that the chlorosulfonic acid could not act as a sulfonating agent in the reaction with secondary amines like 4,4’-Trimethylenedipiperidine (TMDP) and Piperazine (PZ) probably due to more steric hindrance of the sulfur atom by chlorine and oxygen atoms. Then, the dual solvent-catalyst activity of these ionic liquids was demonstrated for the synthesis of novel triazole-pyrimidines through a one-pot three-component reaction under mild conditions. The arene diazonium saccharin derivatives were initially produced from various substituted aromatic amines; subsequently, these intermediates were treated with a greener organic iodide for the preparation of the aryl iodide. The arene diazonium saccharin intermediates could be stored in the liquid phase in a refrigerator for a long time with no significant loss activity. The ionic liquids were retrieved and reused several times without reducing their catalytic efficiency
Performance of waterborne intumescent coating with hybrid industrial and biofillers for steel protection / Khairunisa Md Nasir
Get PDFIn recent decades, the disastrous accidents caused by damaged steel structure in the event of the fire have reminded people of the risk of fire in industrial buildings. The use of intumescent coatings is one of the most efficient methods to protect materials against
fire. The coating comprises three active elements bounded together with a binder, which then reacts together at higher temperatures. Under the action of heat, the coating expands and forms a thick porous char layer to insulate the substance, thereby prolonging the building from collapsing under severe fire conditions. Considering ecological issues, the use of waterborne resin as a binder will minimise smoke and toxic fume emission. Meanwhile, the use of synthetic solvent borne resin can have an adverse effect because intumescent coatings contain synthetic polymers which release acidic degradation products and cause water pollution. Selection of a filler to be introduced in flame retardant properties is determined by several factors which include chemical compatibility during the mixture, suitable viscosity and residue left after decomposition thermal analysis. In this research, the single filler system involves industrial fillers commonly used in many industries namely, titanium dioxide (TiO2), aluminium hydroxide (Al(OH)3), magnesium hydroxide (Mg(OH)2) and calcium carbonate (CaCO3). The search for more environmentally friendly intumescent coatings has led to the utilisation of rice husk ash (RHA) and chicken eggshell (CES) as biofillers hybrid with industrial fillers, TiO2 and Al(OH)3 reinforcing the quality and effectiveness as hybrid fillers system. Incorporating waste biofillers specifically into coatings can greatly minimise cost and reduce the amount of wastes. Both intumescent coating systems were investigated based on three characterisations; (a) physical and chemical properties; (b) fire performances test; (c) mechanical test. The hybrid fillers system was evaluated in extensive fire standard analysis using fire propagation test (BS476: Part 6), surface spread of flame (BS476: Part 7) and cone calorimeter to identify the key combustion properties of coating material properties. The higher charred yields demonstrated by coatings with TiO2 and CaCO3 have led to the lower equilibrium temperature below 300°C, while coating with Al(OH)3 showed an excellent flammability resistance with the highest oxygen index value of 35. Hybrid coating with TiO2/RHA showed satisfactory fire behaviour effect in terms of char expansion rate, lowest total heat release rate and last to ignite, while hybrid coating with TiO2/Al(OH)3/RHA/CES presented the lowest amount of released CO and high CO2 production percentage. This research presents the significant improvement of hybrid fillers system, where all coatings required high oxygen concentration to support the burning process. From the BS 476: Part 7, all coatings were classified as Class 1 (the bestclass) showing least distance of flame spreading and also fulfilled the best Class 0 which limits the amount of heat released in BS 476: Part 6. The originality of this work was emphasized on the intumescent coating with the addition of RHA and CES as biofillers hybrid with industrial fillers. In addition, waterborne resin was used to minimise the volatile organic compound emissions from synthetic solvent-borne binder
Testing the minimal bounded space method on vision-based drone navigation / Yap Seng Kuang
No full textThe object-based approach is the most common in developing navigation strategies for robots. The object-based approach focuses on segmentation, detection, annotation, and recognition of objects or markers in the scene. For a drone, this approach is popular with the utility of sensors such as laser, vision (mono and stereo), ultrasonic, Kinect, and others. To elicit the information required, often, the object-based approach relies on these sensors as a hybrid solution. Recently, the availability of the deep learning algorithm also encourages the object-based approach for drone navigation. A critical gap in the object-based approach is that the computational resources required are massive. For a drone, especially a low-cost one, this renders the object-based approach to simulation-based only works. The other, less common navigation strategy for robots is the space-based approach. In the space-based approach, there is no object learning. Without object learning, there is no advanced processing to perform object recognition or labeling. The space-based approach is focused on computing the openings in the surrounding space. Recent works have experimented with the space-based approach for robot navigation (Azizul, 2013; Azizul & Khanil, 2017). The space-based method used is called the Minimum Bounded Space (MBS). The name of the method is obtained from trying to bound the spatial openings immediately to the robot. In the earlier work, Azizul (2013) tested the MBS on a mobile robot equipped with a laser sensor. There is no imaging involved, but the laser sensor does record depth information. The spatial openings are derived by analyzing occlusion information from the environment, which is available from the depth information. The laser robot is shown to navigate autonomously by moving from one spatial opening to another in an indoor environment. In the later work, Azizul & Khanil (2017) experimented with the MBS on a mobile robot equipped with a camera. Imaging is involved, but the way they processed the image is not the same as the processes involved in object-based works. Floor segmentation and analysis become the basis for finding spatial openings immediately to the robot. Eliciting the openings in the indoor environment is achieved without depth information. The results shown from these prior works are encouraging as they do not require complex processing. Furthermore, they show how MBS is successfully implemented for real-time robot experiments. Interestingly, they show the versatility of the MBS method for autonomous robot navigation with or without depth information. However, the MBS method has not been tested on a flying robot or the outdoor environment. In this work, I show how the MBS method is implemented as the navigation strategy for a low-cost drone. The drone used in this work is called the Parrot Bebop Drone, which is equipped with a camera on board. To complete this task, I have developed a new computer vision framework to elicit openings for the MBS. The testing done shows the MBS is useful for low-cost drones flying in an indoor and outdoo
Regulatory enforcement of minimum wage policy: An examination of street-level bureaucrats’ discretion in Malaysia / Mohammed Salah Hassan
No full textRegulatory enforcement is a multifaceted phenomenon that revolves around the concept of discretion of Street-Level Bureaucrats (SLBs). Discretion can be defined as the ability to freely decide on how to deliver services to the clients/public. Regulations are enforced by the decisions made by bureaucrats when they interact with clients. By combining street-level bureaucracy and responsive regulation theories, this study is set to examine how different factors shape the discretion of street-level bureaucrats.
This study is built on available literature pertaining to SLBs and policy implementation to provide a comprehensive understanding of regulation enforcement in Malaysia. SLBs are the Labor Inspectors who are responsible for the enforcement of minimum wage in Malaysia. The study’s main contribution is examining how personal characteristics, internal organizational factors, and a multidimensional enforcement style shape the discretion of bureaucrats in Malaysia. The study’s main finding highlights that Labor Inspectors in Malaysia demonstrate a range of enforcement style dimensions when enforcing the minimum wage. The novelty of this thesis is in highlighting two main constructs; willingness to implement, and client meaningfulness, and their importance in shaping policy implementation and its effect on street-level bureaucrats' behavior, also these constructs are likely contributing to the imperfect enforcement of the minimum wage policy. Furthermore, this study demonstrates that enforcement style consists of three dimensions; legal, facilitation, and accommodation. Finally, the empirical finding of this study highlights that discretion of street-level bureaucrats is influenced by various factors that ultimately define the enforcement process
Viral lysis as top-down control of bacterial production in tropical waters of Peninsular Malaysia / Stanley Chai Choon Yip
No full textViruses are the most abundant biological entities in the biosphere. Viruses infect host cells for replication and survival. Hence, viruses play important roles in the nutrient cycles and genetic transfer. Viral lytic and lysogenic life cycles have different effects to the ecosystem as lytic cycle leads to production of more virus particles and death of host cells whereas lysogenic cycle produces prophage that reproduce along with the host cell. However, the environmental changes such as temperature increment and eutrophication may cause the shift of the lysogenic to lytic life cycle which may affect the host cell community. The changes of viral life cycle and community structure of bacteria and phytoplankton due to environmental change will bring significant consequences onto biogeochemical cycles. The water samples were collected from nearshore (Port Klang and Port Dickson) and offshore waters (Yan and Kuala Rompin) surrounding Peninsular Malaysia. Bacterial production, virus production and protist grazing at each sampling sites were measured. Microcosm experiment were carried out to determine the relationship of seawater warming and eutrophication with viral dynamics. Mitomycin C was used to induce viral lytic life cycle. Observations revealed site-dependent differences in dissolved inorganic nutrient concentration, TSS (43.3 – 106.7 mg L-1), dissolved oxygen (148 – 265 μM), Chl a (0.21 – 3.54 μg L–1) and bacterial abundance (4.09 × 105 – 9.41 × 105 cells mL–1). However viral abundance (measured as virus-like particles or VLP) (1.04 × 106 – 2.39 × 106 VLP mL–1) and virus production rates (0.59 × 105 – 4.55 × 105 VLP mL–1 h–1) were not coupled to neither bacterial abundance nor production (0.85 × 104 – 6.42 × 104 cells mL–1 h–1). The uncoupling was probably due to the bacterial replete state as suggested by the low virus to bacteria ratio (1.8 – 4.3). Ex situ experiments were carried out to investigate the effects of seawater warming (25 – 37°C) and eutrophication (0.1 – 1.0× marine broth concentration) on viral dynamics. Both seawater warming and eutrophication were able to induce lysogen to switch from lysogenic to lytic cycle as the result showed increased virus production (R2 > 0.537) and decreased lysogeny (R2 > 0.896). From this study, eutrophication was a more important driver for virus production. Therefore, with the increasing eutrophication at the coastal waters, the role of viruses in the marine microbial food web will gain importance as virus production increases. Enhanced virus production will drive the habitat towards heterotrophy as increased viral lysis will promote organic matter supplies for the bacterial growth, and will further affect biogeochemical cycling
A digital game-based learning framework for enhancing primary school students’ critical thinking skills / Mahmood Haitham Hussein
No full textCritical thinking is an essential skill that helps people to achieve success in a 21st-century global market that favours individuals capable of thinking critically. However, more traditional teaching methods have fallen short in terms of enhancing students’ critical thinking skills. Thus, researchers are exploiting recent technological developments to incorporate technology in education. Among various other technology-supported teaching methods, digital game-based learning (DGBL) has been identified as an effective approach to promoting students’ interest in learning and improving their critical thinking. Despite this interest, however, research shows that there is a paucity of DGBL applications based on specific frameworks, especially in the area of critical thinking. This research addresses this issue by proposing a framework comprising 6 components – inquiry, communication, mystery, decision making, challenge, and rewards (ICMDCR) – that aims to improve primary school students’ critical thinking. It was hypothesised that the ICMDCR framework would significantly improve students’ critical thinking and science subject scores. The researcher conducted a quasi-experimental study with an experimental group (N = 62) and a control group (N = 62) to test these hypotheses and assess the effectiveness of the framework. Results from repeated-measures analysis of variance (ANOVA) and post-hoc Bonferroni tests revealed that only students in the experimental group who played Ecoship Endeavour significantly improved their critical thinking (pre-test = 12.45, post-test = 15.10) and their science subject scores (pre-test = 56.66, post-test = 77.50). In addition, results showed that students in the control group who were taught via the traditional method experienced a considerable decrease in their critical thinking scores (pre-test = 11.98, post-test = 11.15), while their science scores did not significantly improve (pre-test = 55.32, post-test = 57.68). This framework can assist researchers and game developers in designing DGBL applications that refine students’ critical thinking capabilities. Moreover, students can use this game to enhance their critical thinking and participate in an engaging learning environment
RSM-based optimization study on polysaccharide production by wild-Serbian Ganoderma applanatum strain (BGS6Ap) in a batch fermentation / Joshini Pillai Balamurugan
No full textA wild-serbian ganoderma applanatum strain bgs6ap (gasb) from mount kosmaj,
serbia was successfully isolated and molecularly identified. molecularly, gasb
generated 651 base pairs that were sequenced and found to be a different strain of g.
applanatum strain atcc and ganoderma sp. strain gps 047 in the same clade using
ncbi-blast. one factor at a time (ofaat) method was implemented for growth
curve and morphological analysis to study the temperature effect of the mycelium
growth. reflecting on to its natural cold habitat in eastern europe, gasb favoured the
temperature of 25°c for biomass, exopolysaccharide (eps) and endopolysaccharide
(ens) production followed by 20°c and 30°c. morphologically verified, large dense
mycelia pellets exhibited high (biomass-ens) and hairy starburst pellets (eps). growth
curve analysis using liquid fermentation was conducted and differentiated based on the
pellet formation that contributed to biomass (5.04 g/l), ens (0.51 g/l), eps (1.46 g/l)
at temperature of 25°c (biomass, ens) and 20°c (eps). in response surface
methodology, the applied central composite design proved that the experimental results
were found to be significant for biomass and ens production. the results gave the
optimized biomass (17.51 g/l), eps (2.59 g/l) and ens (3.47 g/l) production at day
15 (10g /l of glucose), initial ph 6, 24°c and 153 rpm. extracted eps, ens and glucan
sulphate (gs) gave a confirmation spectral linkage in ftir (between 2928 cm-1 and
889cm-1) and nmr (δ 4.30 and 5.20 ppm) as exo-β-d-glucan and endo-β-d-glucan
when compared with β-d-glucan standard of laminarin. this blueprint could be
employed to achieve high biomass, eps and ens when subjected to high scale
bioreactor system for other temperate medicinal mushrooms