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Study of heat transfer and friction loss of nanofluid suspension flow in square pipe heat exchanger / Jayprasanth Krishnan
Get PDFAn experimentational analysis was done to evaluate heat transfer features of graphene oxide (GO) nanofluid inside the cross section of square cross tube that was exposed to a uniform constant heat flux of the test segments. Lately huge figures of researches have been are proceeded out to examine the outcome of nanofluid in augmentation of the heat transfer rate in numerous heat exchangers particularly using hummer method to attain GO. In this case, advanced hummer method was used to obtain GO and further analyses the effect of the nanofluids. The viscosity and thermal conductivity for the (GO) nanofluids at the concentrations of 0.025%, 0.05%, 0.075%, and 0.1 wt % fixed similarly together with distilled water or known as distilled water before proceeding to the experiments. The heat transfer analysis of the flowing distilled water was compared with (GO) nanofluids using advanced hummer methods. The convective heat transfer coefficient of (GO)-distilled water nanofluid is greater than the base fluid by roughly from 9.7% to 32.7%. Furthermore, the heat transfer coefficient of the (GO)-distilled water enlarged as the flowrate rises. The increase in the pressure drop valued from 13.43% to 36.55%. The friction factor also surges as the values verified from 0.71% to 2.3%. The analysis reveals that more concentration leads to greater heat transfer coefficient, pressure drop and including friction factor
Analysis of space-charge-limited conduction mechanisms in ZrON/SiC system / Nur Hasdyanna Hasnurashid
Get PDFIn this study, current conduction mechanism by space-charge-limited conduction (SCLC) and Poole-Frenkel (PF) emission on ZrON/SiC system that was oxidized and nitrided in N2O at various temperatures (400-900˚C) were analysed. The current-voltage (I-V) measurements were performed in Al-gate metal-oxide-semiconductor (MOS) capacitor by sputtering of Al film on top of the film and at the back of the substrate. Then, characterization of electrical properties was done according to two types of bulk-limited conduction, which are space-charge-limited conduction and Poole-Frenkel emission conduction. Space-charge-limited conduction and Poole-Frenkel emission have been systematically evaluated through data analysis method by the fitting of linear regression according to Ohm’s Law model in J-Vg plot and Poole-Frenkel model in ln (J/E)-E1/2 plot. The mechanisms of the interface traps and the current conducted through oxides were affected by the temperature of simultaneous oxidation and nitridation performed on the sputtered Zr on SiC substrate. Electrical results showed that sample that was oxidized/nitrided Zr/SiC for 15-min duration at 500˚C recorded the highest electric field breakdown (EB) of 5.05 MV/cm at 10-6 A/cm2. Based on the current density and electric field (J-E) plot, the space-charge-limited conduction mechanism by Ohm’s law was analysed. It is found that Ohm’s law conduction occurs at low electric field (-0.4 – 0.05 MV/cm). As for Poole-Frenkel emission, the conduction mechanism occurs at higher electric field range (0.6-1.65 MV/cm). The effect of different oxidation and nitridation temperature on leakage current and electric field breakdown at were compared and discussed
Income inequality and crime: Consumption channel / Nur Annizah Ishak
Get PDFThe general objective of this study is to examine the relationship between income inequality and crime. Many studies have discussed the relationship between inequality and crime. However, all the literature focused on ‘absolute’ measurements, such as income, poverty, Gini index, education, and employment. They neglected the importance of ‘relative concept’ - a missing element of the way economists analyze inequality. This study argues income inequality is visible through conspicuous consumption. Hence this study proposes conspicuous consumption as another possible channel that could explain the relationship between inequality and crime. Specifically, this study comprises of four specific research objectives. The first goal is to examine the relationship between conspicuous consumption and crime among Malaysians. Second, is to measure the relationship between the love of money and crime among Malaysians. Third, is to analyze the role of love of money in mediating conspicuous consumption and crime. The final objective is to propose recommendations for consumption reform of individuals and government to mitigate inequality and crime behavior. A conceptual framework was developed for this study to explain the relationship of three constructs; conspicuous consumption, love of money, and crime. This study adopts Structural Equation Model-Amos (SEM) in investigating the relationship between the three variables. A survey was conducted on public employees in Malaysia to gather the necessary data. The findings suggest three important outcomes. First, a positive relationship between conspicuous consumption and crime where respondents that have higher conspicuous consumption attitude also have higher propensity to commit a crime, particularly through social comparison. Second, there is a positive relationship between the love of money and crime. The survey found they agreed to commit unethical behavior to maximize their profits or utility. Finally, the finding reveals that the love of money significantly mediates the relationship between conspicuous consumption and propensity to crime. All of these findings suggest that conspicuous consumption leads to crime. Consumption is not only important for economic utilization but also to determine one’s status in society. As ‘seeking status’ is universal for society, hence it produces a social comparison. The desire for social conformity, particularly to ‘keep up with the Joneses’ combined with the love of money could induce crime. In summary, this study expands the previous literature by providing a possible explanation of the relationship between income inequality and crime. It contributes to the existing academic research by introducing conspicuous consumption as a result of income inequality. This new variable fills in the research gap by providing additional evidence to the inconclusive relationship between inequality and crime. Some implications and recommendations could be taken into consideration in order to mitigate luxury spending or conspicuous consumption behavior. Among them are to regulate consumption, to impose a tax on luxury goods and prudent spending
Non-invasive tests for the detection of nasopharyngeal carcinoma / Sivanesan Vijaya Mohan
Get PDFNasopharyngeal carcinoma (NPC) is a malignancy that arises in the epithelium of the nasopharynx. Diagnosis is often delayed due to inaccessibility of primary tumour site which leads to inaccurate biopsy. The pathogenesis of NPC is linked to the Epstein-Barr virus (EBV) and studies have shown the employability of plasma EBV DNA for the detection and monitoring of NPC. MicroRNAs (miRNA) are a class of small non-coding RNA that are dysregulated in various cancers and have been extensively studied as biomarker due to their stability in various biospecimens. The aim of this project is to evaluate the load of EBV DNA and dysregulated miRNAs as potential biomarkers to detect NPC in two non-invasive samples from nasal washings (NW) and saliva (SL). Thirty-five NPC and 64 non-NPC patients were included in this study. Two different quantitative polymerase chain reaction (qPCR) assays, which targeted the EBNA1 gene and the BAMHI-W region of the EBV genome, were evaluated to quantify EBV DNA load, and evaluate their accuracy. Twenty-seven human and EBV miRNAs were shortlisted from datasets deposited in the Gene Expression Omnibus (GEO). Expression of these miRNAs were first evaluated in 6 NPC and 6 non-NPC tissues samples and then validated in the NW sample set using reverse transcription qPCR (RT-qPCR). Receiver Operating Characteristic (ROC) analysis was used to calculate the area under the ROC curve (AUC) to evaluate these biomarkers as classifiers for NPC. Multiple Logistic Regression (MLR) was performed to determine if the combination of these biomarkers will lead to an NPC classifier panel with improved accuracy. EBNA1, BAMHI-W, miR-21, miR-26a, miR-29c, miR-93, miR-205, miR-375 and miR-421 were upregulated in NPC samples compared to controls (p<0.05). MLR showed that combination of EBNA1 and miR-21 produced the best AUC of 0.860 with 80.0% sensitivity, 78.1% specificity. Thirty-five NPC and 25 non-NPC saliva samples were analysed in this study. The load of EBNA1 together with 30 human and EBV miRNAs were evaluated in these samples. EBNA1 was not differentially expressed but miR-363-3p, miR-20a-5p, miR-222-3p, miR-126-3p, miR-361-5p, and miR-21-5p were significantly upregulated (p<0.05) in NPC compared to non-NPC saliva samples. MLR analysis showed that best biomarker candidate was miR-21 alone resulted in a ROC 0.6571 with 71% sensitivity, and 48% specificity, indicating that these SL biomarkers were not optimum classifiers of NPC. This study shows that biomarkers in NW could potentially be a non-invasive screening test for NPC
Study of heat transfer and friction loss of nanofluid suspension flow in circular pipe heat exchanger / Sandru Ramadas
Get PDFThis stated experiment focused on the study of convective heat transfer and friction loss in a circular flow passage for Graphene oxide-based nanofluids which are consist of Graphene Oxide/Distilled water with their different wt. % concentrations. These GO/DW based nanofluids where been prepared by using a facile two-step method, while the GO particles were synthesized by a modified hummer method. Four different (0.025, 0.05, 0.075, and 0.1 wt. %) were produced by dispersing graphene particles in distilled water under high probe sonication. The GO/DW based nanofluids flowing in a horizontal shell and tube heat exchanger counter flow under turbulent flow conditions where been investigated for heat transfer, Nusselt numbers, pressure drop, and friction loss studies. The constant heat flux and varying flow rate conditions have been used to analyse the heat transfer improvement in a circular heat exchanger. The results show the convective heat transfer coefficient of the nanofluids is slightly higher than the base fluid at the same flow rate and the same inlet temperature. The heat transfer coefficient of the nanofluids increases with the increase of flow rate, also the heat transfer coefficient increases with the increase of the concentration of the nanofluids, however, an increase in the concentration causes the increase in the viscosity of the fluid leading to a slight increase in the friction loss. As for further analysis, distilled water where been compared with graphene oxide (GO/DW) base nanofluids to compare their heat transfer, Nusselt numbers, and pressure drop variations
Comparison of pressure-assist silver sintering to tin silver solder alloy as die attach material in high power semiconductor / Erik Nino Tolentino
Get PDFThe research is focused on pressure-assisted silver sintering material that is compared to tin silver solder alloy paste as used in power electronics. Material characterization, electrical tests, and reliability tests were conducted in the experiment. After drying process, it was observed that the Ag sintering paste height was reduced to approximately 40 percent. Die attach shear test showed that the average reading is about from 200 to 600 grams which are already enough to hold the dice before proceeding to the pressure sintering process. X-ray revealed that the void percent for SnAg paste sample is about 1.5 percent while pressure-assist Ag sintering paste sample doesn’t have any voids after build. Scanning electron microscopy (SEM) microstructure analysis showed that the SnAg solder sample will form Sn-Ag and Sn-Cu intermetallic compounds between the solder alloy after reflow. For Ag sintering sample, it was observed that the die-to-Ag sintering and Ag sintering-to-DBC joint were properly executed. Agglomeration and aggregation take over in Ag-Ni sinter particles. The diffusion of Ag sintering material in die TiNiAg back metal and Cu DBC was also detected. This acquiring a mechanical lock that forms solid-state diffusion in the system. Electrical test reading shows that the VGE and VCES measurement reading for Ag sintering sample is lower compared to SnAg solder alloy sample. The thermal shock and temperature cycle test that were performed in both samples are comparable in performance. The power cycle test runs on the other hand give the opposite output response. SnAg solder sample only reaches the 20000 cycles but failed at 40000cyle. However, Ag sintering sample reaches 60000 cycle without failure
Catalytic esterification of palm-based lauric acid diethylene glycol via microwave heating / Noor Azeerah Abas
Get PDFDiethylene glycol esters of fatty acids are mixtures of diethylene glycol mono- and di-esters of saturated and unsaturated fatty acids derived from edible oils and fats. The products are produced either by direct esterification of diethylene glycol with fatty acids or by transesterification of diethylene glycol with oils or fats. This study involved in maximizing the conversion of lauric acid to glycol ester via esterification with diethylene glycol, aided by calcined Zn-Mg-Al catalyst in a 250-ml reactor using both conventional and microwave heating. Preliminary catalytic screening involving tin (II) oxalate, Amberlyst-15 and calcined Zn-Mg-Al catalysts in esterification of lauric acid and diethylene glycol via microwave heating resulted 65.4%, 31.6% and 95.4% of lauric acid being converted, respectively. In addition, conversions obtained from the solid acid catalysts appeared to be higher than autocatalytic esterification of only 15.8%. The optimum operating condition for esterification via microwave heating was established at 190 oC, 2:1.3 mole ratio of lauric acid to diethylene glycol with 5% of catalyst dosage for 90 min. Calcined Zn-Mg-Al catalyst under optimised condition gives 98.2% of lauric acid conversion. The recyclability of the catalysts in the esterification of lauric acid with diethylene glycol were also carried out. It shows that calcined Zn-Mg-Al and tin (II) oxalate both can be used up to six cycles as compared to Amberlyst-15 catalyst that has lost part of its activity after the third cycle. The microwave heating remains attractive for heating catalytic esterification as it accelerates the reaction speed at shorten period of time from 8 hours to 1.5 hours as compared to conventional heating
Ionic liquid functionalized β-cyclodextrin modified electrode as electrochemical sensor for 2,4-dichlorophenol / Fairuz Liyana Mohd Rasdi
Get PDFThis thesis described the synthesis and characterization of ionic liquid monofunctionalized β-cyclodextrin (β-CD-1-BIMOTs) and ionic liquid difunctionalized β-cyclodextrin (β-CD-2-BIMOTs) for sensor applications. The physical characterizations of these compounds have been conducted using nuclear magnetic resonance (NMR), Fourier transform infra-red (FTIR), energy dispersive x-ray (EDX), x-ray diffraction (XRD) and Brunauer-Emmet-Teller (BET) analyses. These compounds were used as modifiers for carbon paste electrode (CPE). Cyclic voltammetry and chrono-amperometry methods were employed to examine the electrochemical responses of all prepared CPEs. All prepared electrodes show responses towards the target analyte of 2,4-dichlorophenol (2,4-DCP). Both β-CD-1-BIMOTs/CPE and β-CD-2-BIMOTs/CPE give higher current (i) responses compared to β-CD/CPE and native CPE. The optimum potential value for the oxidation of 2,4-DCP was decreased with the increase of IL substitution on β-CD which was from 0.75 V (β-CD-1-BIMOTs/CPE) to 0.68 V (β-CD-2-BIMOTs/CPE). Under the systematic optimized and validated conditions, the i response and the concentration of 2,4-DCP had a good linear relationship in the range of (4.3 – 100) ×10-6 mol L-1 and (13.8 – 100) × 10-6 mol L-1; respectively for β-CD-1-BIMOTs/CPE and β-CD-2-BIMOTs/CPE. Both sensors were successfully applied for the determination of 2,4-DCP in leachates from landfill, mineral water and lake water with the recovery of 85.5% - 117.7%. From the interference study, β-CD-2-BIMOTs/CPE was unable to differentiate the response between 2,4-DCP and its analogues where the change of signals >5% in comparison to β-CD-1-BIMOTs/CPE. The possible interaction geometries of the β-CD-1-BIMOTs-2,4-DCP and β-CD-2-BIMOTs-2,4-DCP were proposed to investigate the significant differences in the oxidation potential values and the selectivity properties between both sensors through spectroscopic techniques (NMR and ultraviolet-visible (UV-Vis))
The influence of facebook social interaction on healthy eating behaviour and work productivity / Wong Wen Yin
Get PDFIn the current competitive global environment, one of the core determinants of the business success lies in the foundation to workplace productivity amongst the employees. The rise of social media in the health domain can have it play the role of an alternative channel for the promotion of healthy eating behaviour. Literatures outlined that social interaction on Facebook seems relevant towards the promotion of positive health behaviour(s). However, details pertaining to the interaction and its subsequent impact on health remains unexplored. This research examines the influence of Facebook social interaction on healthy eating behaviour and its subsequent impact on work productivity.
Using the quantitative research approach, data were collected using self-administered questionnaires. The questionnaires were distributed to working adults online who used Facebook, while its paper counterparts were distributed via snowball, purposive, and convenient sampling. A total of 770 usable responses were collected within 8 months. The structural equation model (SEM) technique was used to assess the proposed research framework.
All seven hypotheses proposed in this research were accepted. Both social ties and Facebook use were found to have a positive influence on social interaction on Facebook. The results indicated that social interaction on Facebook plays a significant role in improving healthy eating knowledge, leading towards more positive healthy eating attitude, which in turn results in healthy eating behaviour and increased work productivity.
This research pioneered the understanding of the role of Facebook for healthy eating behaviour and work productivity. It integrated two theories, namely social capital theory and consumer socialisation theory for the construction of a comprehensive theoretical framework, which describe the determinants and influence of Facebook social interaction on individuals’ healthy eating attitude, knowledge and behaviour, leading to increased work productivity. The theoretical contribution of this research lies in its extension and verification of social capital theory and consumer socialization theory in online settings, especially in the context of social media. Social ties and Facebook use are introduced as the new antecedents to the existing consumer socialization framework. The findings from this research provide an imminent foundation for organizations when formulating strategies for workplace healthy eating promotion for enhancing work productivity. Facebook can be used to as an effective tool and platform to reach and communicate with the employees about healthy eating.
This research confirmed that Facebook could help organizations reach their employees for cultivating healthy eating behaviour and increase work productivity. This research is noteworthy in its contribution towards the advancement of the discipline of health behaviour and productivity management with the application of social media
Thanking strategies in the filmfare and academy award acceptance speeches / Savithiammal David
No full textThe present research endeavours to shed light on the thanking strategies that are used by the recipients of the Filmfare Awards and the Academy Awards in their acceptance speeches. Award acceptance speeches are direct expressions of gratitude. However, to date no research has been done on it. Therefore it is imperative to investigate the thanking strategies employed in these acceptance speeches in an attempt to close the gap in this field. To understand and define the thanking strategies, various models and theories of thanking are explored, which in turn shed light on several important concepts. The characteristics of the thanking is that it is an expressive speech which functions as a tool to express gratitude towards a beneficial act by a third party. In an attempt to identify various thanking strategies, the current research delves into literature that investigates various thanking strategies and their realizations. Using a quantitative and qualitative approach this study attempts to obtain a clear insight into the thanking strategies used by the recipients of the six main categories of the Filmfare and Academy Awards in their acceptance speech. The acceptance speeches are coded based on the thanking strategies put forward by Aijmer (1996). The findings of this study demonstrate that the recipients of the Academy Awards uses more thanking strategies than the recipients of the Filmfare Awards. The findings reveal that the most used thanking strategy is thanking somebody explicitly while the least used thanking strategy is commenting on one’s own role by suppressing one’s own importance. The results also identify the formulaic expression ‘thank’ and the base of the realization of thanking. The research proposes recommendations on how Aijmer’s (1996) thanking strategies can be incorporated in the readers’ speeches when expressing gratitude which is difficult even for native speakers