Universiti Teknikal Malaysia Melaka: UTeM Open Journal System
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Numerical Investigation of the Water/Alumina Nanofluid within a Microchannel with Baffles
Get PDFThe study of heat transfer phenomenon in microchannels has attracted researchers’ attention as they have many advantages in the cooling of electronic components. In this numerical study, the effect of adding alumina nanoparticles to the water flow through a microchannel with some baffles embedded on the top and bottom walls is numerically discussed by using ANSYS Fluent software. The several cases including the effect of various volume fraction of nanoparticles (2, 4, 6, and 10%), Reynolds number of the inlet flow (10, 20, 30, 40, and 50), and the number of baffles and their heights on the heat transfer phenomena are investigated. The local Nusselt number, the average outlet temperature, and the streamlines are presented for representing the results. The results show that increasing the Reynolds number decreases the average outlet temperature. Moreover, the increase in the number of baffles causes an increase in the average outlet temperature since the formation of vorticities just behind of each baffle and results in a large heat transfer rate. As the baffles height increase, the strength and the area of the vortices increase and hence the heat transfer rate increases. However, an increase in the volume fraction of the nanoparticle increases the average outlet temperature which is due to the increase in conduction heat transfer of nanoflui
The effect of different shape pattern of metal interconnects on the electrical and mechanical properties of stretchable conductive circuit
Get PDFElectrically conductive adhesive (ECA) had been extensively studied to replace the Sn/Pb solder mainly found in printed circuit boards (PCBs) because of their harmful action towards human health and environment. In the production of stretchable PCBs, ECA mainly comprises of metallic filler and polymer matrix should perform good electrical and mechanical properties when straining being loaded. Therefore, determining the optimum shape pattern to be printed will contribute toward the desired traits of stretchable PCBs. In this study, commercial silver ink and thermoplastic polyurethane (TPU) as substrate was used. The ink was printed on the substrate by doctor-blade technique with different shape patterns with varies widths (1mm, 2mm and 3mm): (a) straight, (b) zigzag, (c) square and (d) sinusoidal. Then measurement of sheet resistance by four-point measurement was conducted on unloaded and loaded straining of shape pattern. This study exhibited that 3mm width zig zag shape pattern can elongate the highest straining (5% strained) compare than others patterns. In the meanwhile, straight and square shape pattern did not tolerate to any deformation which when straining at a minimum elongation of 0.1mm, the conductivity already lost. In conclusion, further study purpose, more analysis were suggested like analysis on the silver composition, curing temperature variation as well as the distribution of stress in printed shape pattern by 3D Finite Element Analysis (FEA) can be done for the more reliable study
DOES RELIGIOSITY INFLUENCE THE RELATIONSHIP BETWEEN EMOTIONAL FACTORS AND WORKPLACE DEVIANT BEHAVIOUR?
Get PDFDrawing from social control theory, this study tested a moderating influence of religiosity in which emotional exhaustion and emotional stability as predictors and workplace deviance behavior is the outcome. Using data from 350 employees from the multimedia organization in Malaysia, we conducted Structural Equation Modelling analysis. Results found a positive and significant relationship between emotional exhaustion and workplace deviance behavior and negative impact of emotional stability towards workplace deviance behavior. Finally, religiosity moderates the relationship between emotional exhaustion and workplace deviance behavior, and religiosity moderates the relationship between emotional stability and workplace deviance behavior. The study makes a significant and unique contribution to the literature by showing the moderating influence of religiosity in the relationship between emotional exhaustion, emotional stability, and workplace deviance behavior. This study suggested that the employee with strong religious, mayreduce emotional exhaustion and enhance employee emotional stability, and thus, mitigate employee to engage in workplace deviance behavior. Keywords: religiosity, emotional exhaustion, emotional stability, workplace deviant behavio
IMPROVING ELECTRONIC DOCUMENT CONTROL APPROVAL PROCESS THROUGH E-CERTIFICATION
Get PDFThis paper analysed factors that influenced the document rejection rate in a semiconductor manufacturing facility. One of the factors that affected document rejection rate was a wrongly written process parameter which caused failure in data extraction. This resulted in many processes on the manufacturing floor to be placed on hold, hence, delaying product delivery to customers. Through current approval workflow, specification writers are required to be trained and certified prior to submitting any revised or new documents for approval. It is important to have the revised specifications approved on first time submission to ensure prompt document update. Hence, the main idea of this work was to improve the approval workflow through reducing number of documents rejection rate during the approval process. This approval workflow was conducted through electronic certification using an electronic document management system (e-DMS). A 3-level electronic certification process for specification writers was introduced to ensure that only certified writers could revise or edit any specifications. The new certification process was successfully implemented and the data were closely monitored for the period of 6 months. The outcome showed 4% improvement on document rejection rate during the approval process. The number of documents submitted for approval within the same period was also increased by 28%
Computational Fluid Dynamic Simulation: Maximise The Percentage Of Air Distribution Inside Quasi-Flow Heat Exchanger
Get PDFParallel plate quasi-flow air-to-air heat exchanger has been implemented in Heat Recovery Ventilation (HRV) system to enhance the operating efficiency even in small temperature difference. In the HRV system, heat energy from the exhaust air is recovered to pre-treat the fresh air coming into the air-conditioning systems. Therefore, the HRV system can reduce the power consumption of Heating, Ventilation and Air Conditioning (HVAC) systems by enhancing the performance of the HRV system. Air velocity distribution over the plate of heat exchanger has a strong effect on the HRV system performance. The higher the percentage of area covered with air across the plate, the higher the heat transfer rate between two airstreams.Inside the plate of the heat exchanger, duct inlet entrance causes air distribution to be non-uniform. Factor affecting air velocity distribution over the plate is investigated to reduce air velocity maldistribution. A simulation using ANSYS is conducted to investigate the effect of different louvres arrangements on the air velocity distribution across the plate of the heat exchanger. Results show that, with a smaller louvre orifice, Mode 1 performs best in term of air velocity distribution, and Turbulence Kinetic Energy (TKE) intensity due to turbulence flow generated at louvre arrangement and complement the effect of pressure drop across the plate. Mode 1 enhances the performance of the HRV system by increasing the percentage of air distribution across the plate with an approximation of 97%
Voltage Variation Analysis by Using Gabor Transform
Get PDFVoltage variations which include voltage sag, swell and interruption are simulated and analyzed in this paper. Various types of parametric equation are generated with the help of MATLAB software. Simulated signals are studies by using time-frequency distribution (TFD) technique. The TFD method used in this paper is the Gabor transform which is less applied by the researchers. The signal parameters used in this paper are the RMS voltage and instantaneous power can be extracted from the TFR to study the distinctives of the voltage variations. The parameters extracted can detect the voltage variation signals successfully. The voltage variation signals are successfully detected by using the K-Nearest Neighbors (kNN) algorithm with the implementation of signal parameters extracted as the input on the classifier. The voltage variations waveforms as well as the signal parameters obtained are suitable to be further analyzed
MECHANICAL PROPERTIES OF THICK AND THIN AA1100 WELDED USING BOBBIN FRICTION STIR WELDING
No full textThis study is to investigate the mechanical properties of thick and thin material welded using Bobbin Friction Stir Welding technique. The material that used for this study was Aluminium Alloy 1100 with the thickness of 3mm and 6mm. The aim of this study is to identify the process sensitivity for different material thickness. Different tapered shoulder was tested in this study and the spindle speed and welding speed were varied. There are two sets of parameters used which are 900 rpm and 310 mm/min; and 1440 rpm and 190 mm/min for spindle speed and welding speed respectively. The welding process was done by CNC Milling Machine. The welded products were tested using tensile test, micro hardness, and XRD analysis. The result shows that low spindle speed and higher travel speed produce good weld. This only can be produced with small tapered angle on the shoulder of the tool that represents the best tapered angle used in this study. If not, defect such as open tunnel, teared material at tool entry and void will be produced. However, the welding for thin materials is challenging and for different material thickness, optimized parameter should be used for high strength weld
A Study on Principal Component Analysis over Wireless Channel
Get PDFApplications in many fields such as the internet of things (IoT), stock market, image compression, food adulteration, wireless physical layer key generation, etc. are becoming progressively complex due to a large number of users and increment in their usage. Data obtained by these applications are in huge amount creating a high computational cost. Further, it is difficult to handle and analyze it. To deal with such problems, dimensionality reduction techniques are used and one of the dimensionality reduction techniques is the Principal Component Analysis (PCA). In this paper, PCA is applied over a wireless Rician channel with AWGN at different SNR. It is concluded that the information content is more in less number of principal components with samples at higher SNR. It is also observed that the different combinations of several groups and elements in the sample space provide a different cumulative percentage of information
Adaptive Code with Non-Uniform Modulation on OFDM Subcarriers Modeling for Underwater Acoustic Environment
Get PDFIn this paper, an Adaptive Code NonUniform Modulation with Orthogonal Frequency Division Multiplexing (OFDM) System was evaluated in the underwater acoustic communication channel. This system was adopted from the Subcarrier arrangement of the OFDM standard of IEEE 802.11a, and improved with some modifications. There are three schemes in the proposed adaptive system. The first is the Hamming code with Binary phase-shift keying (BPSK) modulated, which is mapped for 12-bit subcarrier data. The second is the Bose-Chaudhuri-Hocquenghem (BCH) code with Quadrature phase-shift keying (QPSK) modulation which is for the other 12-bit subcarrier data. And the third is the Reed Solomon code with 16-Quadrature Amplitude Modulation (16- QAM) modulation that is mapped for 24-bit subcarrier data. The system modeling was evaluated in the shallow water acoustic environments. Bit error rate (BER) and signal-to-noise ratio (SNR) were analyzed to evaluate the proposed system performance. The evaluation results showed that the proposed system was able to improve the performance better than the fixed modulation or un-coded Non-uniform modulation. At the same bit error limit which is 0.001, BPSK, QPSK, 16-QAM, uncoded Non-uniform modulation, and the proposed system have its own SNR, i.e.; 24.9 dB, 8.5 dB, 10.3 dB, 7 dB, and 2 dB, respectively. The proposed system requires lower power to achieve an error rate of 0.001. In addition, between the proposed system and un-coded Non-uniform modulation, it has a coding gain of 5dB
Design and Fabrication of Hairpin Bandpass Filter with Square Shaped Defected Ground Structure
Get PDFIn this paper, the design and simulation of microstrip hairpin bandpass filter with square shaped defected ground structure is described. The method used to design the filter was very efficient and requires less effort. The filter was designed and then simulated on HFSS tool and the results were verified by the fabrication and testing process. The fabrication was performed on the material GaAs The proposed bandpass filter with a square shaped defected ground structure has good performance. The proposed hairpin bandpass filter showed the return loss of -14.69dB at 4.2 GHz, -14.97 dB at 4.8 GHz, and - 19.15 dB at 5.6 GHz, -17.13dB at 6.5GHz, -13.7dB at 7.3 GHz. The insertion losses with square shaped defect were 0.8dB/0.3dB/0.16dB/0.8dB/1.4dB. 3dB and the bandwidth of proposed bandpass filter is 700 MHz/ 150 MHz/ 200 MHz /100 MHz/and 85 MHz at the center frequencies of 4.2 GHz/4.8 GHz/ 5.6 GHz/ 6.5GHz/ 7.3 GHz. In this work, the area has been reduced by 33%