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Selected Works

Faculty of Engineering University of Malaya

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Full-Text Articles in Engineering

Investigation About The Characterization Of Machine Tool Spindle Stiffness For Intelligent Cnc End Milling Aug 2015

Investigation About The Characterization Of Machine Tool Spindle Stiffness For Intelligent Cnc End Milling

Faculty of Engineering University of Malaya

This paper describes how to investigate the characterization of the machine tool spindle stiffness in radial direction for precise monitoring of cutting forces in end milling process by using displacement sensors. Four sensitive eddy-current displacement sensors are installed on the spindle housing of a machining center so that they can detect the radial motion of the rotating spindle. Thermocouples are also attached to the spindle structure, and the stability of the displacement sensing is examined. The change in spindle stiffness due to the spindle temperature and the speed is investigated. Finally, monitoring results of small and medium scale cutting forces …

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Strategy For The Biotransformation Of Fermented Palm Oil Mill Effluent Into Biodegradable Polyhydroxyalkanoates By Activated Sludge Jun 2015

Strategy For The Biotransformation Of Fermented Palm Oil Mill Effluent Into Biodegradable Polyhydroxyalkanoates By Activated Sludge

Faculty of Engineering University of Malaya

Management of wastewater by resource recovery approach allows the transformation of wastewater into valuable resources. This work examines the biotransformation of fermented palm oil mill effluent (POME) into biodegradable plastics - polyhydroxyalkanoates (PHA) - through cultivation and enrichment of PHA-accumulating organisms in activated sludge and the subsequent production of PHA by the cultivated sludge. Enrichment of PHA-accumulating organisms via aerobic dynamic feeding process was effective and had significantly enhanced the PHA storage capacity of the sludge (wt% PHA per sludge dry weight) from 4 wt% (seed sludge) to 40-64 wt% (sludge cultivated for 50 days and more). The cultivated sludge …

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Optical Frequency Comb Generation Based On Chirping Of Mach-Zehnder Modulators Jun 2015

Optical Frequency Comb Generation Based On Chirping Of Mach-Zehnder Modulators

Faculty of Engineering University of Malaya

A new approach for the generation of an optical frequency comb, based on chirping of modulators, is proposed and numerically demonstrated. The setup includes two cascaded Mach-Zehnder Modulators (MZMs), a sinusoidal wave oscillator, and an electrical time delay. The first MZM is driven directly by a sinusoidal wave, while the second MZM is driven by a delayed replica of the sinusoidal wave. A mathematical model of the proposed system is formulated and modeled using the Matlab software. It is shown that the number of the frequency lines is directly proportional to the chirp factor. In order to achieve the highest …

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Significantly Improved Photocurrent Response Of Zns-Reduced Graphene Oxide Composites May 2015

Significantly Improved Photocurrent Response Of Zns-Reduced Graphene Oxide Composites

Faculty of Engineering University of Malaya

ZnS-nanoparticles (NPs) reduced graphene oxide (rGO) composites with a high degree of crystallinity and high dispersity were successfully synthesized via a facile solvothermal method in the gelatin medium, during which the formation of ZnS NPs, reduction of graphene oxide and loading of ZnS NPs into the rGO surface occur simultaneously. Gelatin, as a natural capping agent, plays a significant role in controlling the degree of dispersion and coverage of ZnS NPs. The effect of rGO on the crystalline structure and optical properties of ZnS NPs were determined via X-ray diffraction, UV-visible diffused reflectance spectroscopy and photoluminescence spectroscopy. The ZnS-rGO composites …

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Mechanical Properties Of Intermetallic Compounds In Electrodeposited Multilayered Thin Film At Small Scale By Nanoindentation May 2015

Mechanical Properties Of Intermetallic Compounds In Electrodeposited Multilayered Thin Film At Small Scale By Nanoindentation

Faculty of Engineering University of Malaya

Mechanical properties of intermetallic compounds (IMCs) which were formed in electrodeposited Cu/Sn and Cu/Ni/Sn multilayered thin film have been investigated. The layers of Cu, Sn and Ni were formed by electrodeposition technique using copper pyrophosphate, tin methanesulfonic and nickel Watts baths, respectively. After synthesis, samples were subjected to high temperature aging at 150 degrees C for 168 h. Two different types of intermetallics Cu3Sn and Cu6Sn5 were formed in Cu/Sn. After adding ultra-thin layer of Ni (70 nm) in between Cu and Sn layers, (Cu, Ni)(6)Sn-5 was formed after aging at similar condition to that of Cu/Sn. Tin whisker growth …

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Biosensing Enhancement Of Dengue Virus Using Microballoon Mixers On Centrifugal Microfluidic Platforms May 2015

Biosensing Enhancement Of Dengue Virus Using Microballoon Mixers On Centrifugal Microfluidic Platforms

Faculty of Engineering University of Malaya

Dengue is the current leading cause of death among children in several Latin American and Asian countries. Due to poverty in areas where the disease is prevalent and the high cost of conventional diagnostic systems, low cost devices are needed to reduce the burden caused by dengue infection. Centrifugal microfluidic platforms are an alternative solution to reduce costs and increase the availability of a rapid diagnostic system. The rate of chemical reactions in such devices often depends on the efficiency of the mixing techniques employed in their microfluidic networks. This paper introduces a micromixer that operates by the expansion and …

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Evaluating The Optical Properties Of Tio2 Nanofluid For A Direct Absorption Solar Collector May 2015

Evaluating The Optical Properties Of Tio2 Nanofluid For A Direct Absorption Solar Collector

Faculty of Engineering University of Malaya

Recent studies specify that designated nanofluids may increase the proficiency of direct absorption solar thermal collectors. To determine the efficiency of nanofluids in solar applications, their capability to change light energy to thermal energy must be identified (i.e., the absorption spectrum of the solar material). In view of that, this study compares model predictions to spectroscopic measurements of extinction coefficients over wavelengths that are important for solar energy (200- 1100nm). In the first decade of nanofluid research, most of the focus was on measuring and modeling the fundamental thermophysical properties of nanofluids (i.e., thermal conductivity, density, viscosity, and convection coefficients). …

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Experimental And Numerical Investigation Of Heat Transfer In Cnt Nanofluids May 2015

Experimental And Numerical Investigation Of Heat Transfer In Cnt Nanofluids

Faculty of Engineering University of Malaya

Nanofluids with their enhanced thermal conductivity are believed to be a promising coolant in heat transfer applications. In this study, carbon nanotube (CNT) nanofluids of 0.01wt%, stabilised by 1.0wt% gum arabic were used as a cooling liquid in a concentric tube laminar flow heat exchanger. The flow rate of cold fluid varied from 10 to 50g/s. Both experimental and numerical simulations were carried out to determine the heat transfer enhancement using CNT nanofluids. Computational fluid dynamics (CFD) simulations were carried out using Fluent v 6.3 by assuming single-phase approximation. Thermal conductivity, density and rheology of the nanofluid were also measured …

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Single Phase Transformerless Inverter Topologies For Grid-Tied Photovoltaic System: A Review May 2015

Single Phase Transformerless Inverter Topologies For Grid-Tied Photovoltaic System: A Review

Faculty of Engineering University of Malaya

Grid-tied inverters are the key components of distributed generation system because of their function as an effective interface between renewable energy sources and utility. Recently, there has been an increasing interest in the use of transformerless inverter for low-voltage single-phase grid-tied photovoltaic (PV) system due to higher efficiency, lower cost, smaller size and weight when compared to the ones with transformer. However, the leakage current issues of transformerless inverter, which depends on the topology structure and modulation scheme, have to be addressed very carefully. This review focuses on the transformerless topologies, which are classified into three basic groups based on …

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An Islanding Detection Strategy For Distribution Network Connected With Hybrid Dg Resources May 2015

An Islanding Detection Strategy For Distribution Network Connected With Hybrid Dg Resources

Faculty of Engineering University of Malaya

The exponential growth in electricity demand has driven the Distributed Generation (DG) technology a boost in the power system. The use of DG is beneficial to power utilities, DG owners', and end-users in terms of reliability, power quality, and economics. However, to fully utilize the benefits of DGs, some technical issues need to be addressed. Islanding condition is one of the most important issue in this context. Until now, several islanding detection techniques have been proposed for detecting the islanding condition. This paper presents a brief overview of existing islanding detection techniques with their relative merits and demerits. Apart from …

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The Use Of Initial Imperfection Approach In Design Process And Buckling Failure Evaluation Of Axially Compressed Composite Cylindrical Shells May 2015

The Use Of Initial Imperfection Approach In Design Process And Buckling Failure Evaluation Of Axially Compressed Composite Cylindrical Shells

Faculty of Engineering University of Malaya

Thin-walled cylindrical shells are susceptible to buckling failures caused by the axial compressive loading. During the design process or the buckling failure evaluation of axially-compressed cylindrical shells, initial geometric and loading imperfections are of important parameters for the analyses. Therefore, the engineers/designers are expected to well understand the physical behaviours of shell buckling to prevent unexpected serious failure in structures. In particular, it is widely reported that no efficient guidelines for modelling imperfections in composite structures are available. Knowledge obtained from the relevant works is open for updates and highly sought. In this work, we study the influence of imperfections …

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A Review Of Life Cycle Assessment Method For Building Industry May 2015

A Review Of Life Cycle Assessment Method For Building Industry

Faculty of Engineering University of Malaya

A recent study suggested that buildings globally consume up to 40% of energy and responsible for half of world greenhouse gas emission. Introducing life cycle assessment (LCA) to the building industry is important because it can measure every environmental impact involved in every process from cradle to grave systematically. Within the last decade, research on LCA has increased covering from construction process to manufacturing of building materials. The methods to assess buildings are diverse as buildings have different functions, materials, sizes and locations. The aim of this article is to review the LCA methods and to distinguish phases and materials …

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A Review On Thermophysical Properties Of Nanoparticle Dispersed Phase Change Materials May 2015

A Review On Thermophysical Properties Of Nanoparticle Dispersed Phase Change Materials

Faculty of Engineering University of Malaya

A review of current experimental studies on variations in thermophysical properties of phase change material (PCM) due to dispersion of nanoparticles is presented in this article. Dispersed carbon nanotubes/fiber and different metal/metal oxide nano particles in paraffin and fatty acids might be a solution to improve latent heat thermal storage performance. Thermophysical properties such as thermal conductivity, latent heat, viscosity and super cooling of phase change materials (PCM) could be changed for different physical properties of dispersed nanoparticle such as size, shape, concentration and surface properties. Among the nano particles, comparatively carbon nanotubes and carbon nano fiber have shown better …

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Isi Document Delivery No.: Ce6qq Times Cited: 0 Cited Reference Count: 44 Cited References: Adalberth K, 1997, Build Environ, V32, P321, Doi 10.1016/S0360-1323(96)00069-8 [Anonymous], 2005, E38405 Astm, P1 Arena Ap, 2003, Build Environ, V38, P359, Doi 10.1016/S0360-1323(02)00056-2 Asif M, 2007, Build Environ, V42, P1391, Doi 10.1016/J.Buildenv.2005.11.023 Attia S, 2011, State Art Existing E Bare Jc, 2000, Int J Life Cycle Ass, V5, P319, Doi 10.1007/Bf02978665 Blengini Ga, 2010, Energ Buildings, V42, P869, Doi 10.1016/J.Enbuild.2009.12.009 Blengini Ga, 2010, Int J Life Cycle Ass, V15, P652, Doi 10.1007/S11367-010-0190-5 Bribian Iz, 2009, Build Environ, V44, P2510, Doi 10.1016/J.Buildenv.2009.05.001 Buchan Rd, 2003, Estimating Builders Cole Rj, 1996, Build Environ, V31, P307, Doi 10.1016/0360-1323(96)00017-0 Cole Rj, 1999, Build Environ, V34, P335 Ding Gkc, 2007, Build Res Inf, V35, P487, Doi 10.1080/09613210601116408 Fava J, 2009, J Ind Ecol, V13, P491, Doi 10.1111/J.1530-9290.2009.00150.X Fay R, 2000, Build Res Inf, V28, P31 Goedkoop M, 2010, Intro To Lca Guinee Jb., 2002, Hdb Life Cycle Asses, P692 Han G, 2011, Life Cycle Assessmen Huijbregts Maj, 2003, Environ Sci Technol, V37, P2600, Doi 10.1021/Es020971+ Iso, 2006, 140402006 Iso, V2006 Iso, 2006, 14044 Iso, V2006 Iyer-Raniga U, 2012, Build Environ, V47, P138, Doi 10.1016/J.Buildenv.2011.08.001 Khasreen Mohamad Monkiz, 2009, Sustainability, V1, Doi 10.3390/Su1030674 Kofoworola Of, 2009, Energ Buildings, V41, P1076, Doi 10.1016/J.Enbuild.2009.06.002 Lopez-Mesa B, 2009, Build Environ, V44, P699, Doi 10.1016/J.Buildenv.2008.05.017 Mithraratne N, 2004, Build Environ, V39, P483, Doi 10.1016/J.Buildenv.2003.09.008 Monahan J, 2011, Energ Buildings, V43, P179, Doi 10.1016/J.Enbuild.2010.09.005 Ochsendorf J, 2011, Methods Impacts Oppo Ortiz O, 2009, Constr Build Mater, V23, P28, Doi 10.1016/J.Conbuildmat.2007.11.012 Ortiz-Rodriguez O, 2010, Sci Total Environ, V408, P2435, Doi 10.1016/J.Scitotenv.2010.02.021 Ove Arup And Partners Hong Kong Ltd, 2007, Intr Lif Cycl En Ass Peuportier Blp, 2001, Energ Buildings, V33, P443, Doi 10.1016/S0378-7788(00)00101-8 Rebitzer G, 2004, Environ Int, V30, P701, Doi 10.1016/J.Envint.2003.11.005 Rossi B, 2012, Build Environ, V51, P395, Doi 10.1016/J.Buildenv.2011.11.017 Sartori I, 2007, Energ Buildings, V39, P249, Doi 10.1016/J.Enbuild.2006.07.001 Scheuer C, 2003, Energ Buildings, V35, P1049, Doi 10.1016/S0378-7788(03)00066-5 Singh A, 2010, J Monetary Econ, V57, P729, Doi 10.1016/J.Jmoneco.2010.05.012 Suh S, 2007, Int J Life Cycle Ass, V12, P351, Doi 10.1065/Lca2007.08.358 Thiers S, 2012, Build Environ, V51, P276, Doi 10.1016/J.Buildenv.2011.11.018 Thormark C, 2002, Build Environ, V37, P429, Doi 10.1016/S0360-1323(01)00033-6 Utama A, 2008, Energ Buildings, V40, P1911, Doi 10.1016/J.Enbuild.2008.04.017 Utama A, 2009, Energ Buildings, V41, P1263, Doi 10.1016/J.Enbuild.2009.07.025 Van Ooteghem K, 2012, Build Environ, V49, P212, Doi 10.1016/J.Buildenv.2011.09.028 Wu Jg, 2010, Environ Manage, V46, P610, Doi 10.1007/S00267-010-9497-Z Abd Rashid, Ahmad Faiz Yusoff, Sumiani 0 Pergamon-Elsevier Science Ltd Oxford Renew Sust Energ Rev May 2015

Isi Document Delivery No.: Ce6qq Times Cited: 0 Cited Reference Count: 44 Cited References: Adalberth K, 1997, Build Environ, V32, P321, Doi 10.1016/S0360-1323(96)00069-8 [Anonymous], 2005, E38405 Astm, P1 Arena Ap, 2003, Build Environ, V38, P359, Doi 10.1016/S0360-1323(02)00056-2 Asif M, 2007, Build Environ, V42, P1391, Doi 10.1016/J.Buildenv.2005.11.023 Attia S, 2011, State Art Existing E Bare Jc, 2000, Int J Life Cycle Ass, V5, P319, Doi 10.1007/Bf02978665 Blengini Ga, 2010, Energ Buildings, V42, P869, Doi 10.1016/J.Enbuild.2009.12.009 Blengini Ga, 2010, Int J Life Cycle Ass, V15, P652, Doi 10.1007/S11367-010-0190-5 Bribian Iz, 2009, Build Environ, V44, P2510, Doi 10.1016/J.Buildenv.2009.05.001 Buchan Rd, 2003, Estimating Builders Cole Rj, 1996, Build Environ, V31, P307, Doi 10.1016/0360-1323(96)00017-0 Cole Rj, 1999, Build Environ, V34, P335 Ding Gkc, 2007, Build Res Inf, V35, P487, Doi 10.1080/09613210601116408 Fava J, 2009, J Ind Ecol, V13, P491, Doi 10.1111/J.1530-9290.2009.00150.X Fay R, 2000, Build Res Inf, V28, P31 Goedkoop M, 2010, Intro To Lca Guinee Jb., 2002, Hdb Life Cycle Asses, P692 Han G, 2011, Life Cycle Assessmen Huijbregts Maj, 2003, Environ Sci Technol, V37, P2600, Doi 10.1021/Es020971+ Iso, 2006, 140402006 Iso, V2006 Iso, 2006, 14044 Iso, V2006 Iyer-Raniga U, 2012, Build Environ, V47, P138, Doi 10.1016/J.Buildenv.2011.08.001 Khasreen Mohamad Monkiz, 2009, Sustainability, V1, Doi 10.3390/Su1030674 Kofoworola Of, 2009, Energ Buildings, V41, P1076, Doi 10.1016/J.Enbuild.2009.06.002 Lopez-Mesa B, 2009, Build Environ, V44, P699, Doi 10.1016/J.Buildenv.2008.05.017 Mithraratne N, 2004, Build Environ, V39, P483, Doi 10.1016/J.Buildenv.2003.09.008 Monahan J, 2011, Energ Buildings, V43, P179, Doi 10.1016/J.Enbuild.2010.09.005 Ochsendorf J, 2011, Methods Impacts Oppo Ortiz O, 2009, Constr Build Mater, V23, P28, Doi 10.1016/J.Conbuildmat.2007.11.012 Ortiz-Rodriguez O, 2010, Sci Total Environ, V408, P2435, Doi 10.1016/J.Scitotenv.2010.02.021 Ove Arup And Partners Hong Kong Ltd, 2007, Intr Lif Cycl En Ass Peuportier Blp, 2001, Energ Buildings, V33, P443, Doi 10.1016/S0378-7788(00)00101-8 Rebitzer G, 2004, Environ Int, V30, P701, Doi 10.1016/J.Envint.2003.11.005 Rossi B, 2012, Build Environ, V51, P395, Doi 10.1016/J.Buildenv.2011.11.017 Sartori I, 2007, Energ Buildings, V39, P249, Doi 10.1016/J.Enbuild.2006.07.001 Scheuer C, 2003, Energ Buildings, V35, P1049, Doi 10.1016/S0378-7788(03)00066-5 Singh A, 2010, J Monetary Econ, V57, P729, Doi 10.1016/J.Jmoneco.2010.05.012 Suh S, 2007, Int J Life Cycle Ass, V12, P351, Doi 10.1065/Lca2007.08.358 Thiers S, 2012, Build Environ, V51, P276, Doi 10.1016/J.Buildenv.2011.11.018 Thormark C, 2002, Build Environ, V37, P429, Doi 10.1016/S0360-1323(01)00033-6 Utama A, 2008, Energ Buildings, V40, P1911, Doi 10.1016/J.Enbuild.2008.04.017 Utama A, 2009, Energ Buildings, V41, P1263, Doi 10.1016/J.Enbuild.2009.07.025 Van Ooteghem K, 2012, Build Environ, V49, P212, Doi 10.1016/J.Buildenv.2011.09.028 Wu Jg, 2010, Environ Manage, V46, P610, Doi 10.1007/S00267-010-9497-Z Abd Rashid, Ahmad Faiz Yusoff, Sumiani 0 Pergamon-Elsevier Science Ltd Oxford Renew Sust Energ Rev

Faculty of Engineering University of Malaya

Thermal energy storage as sensible or latent heat is an efficient way to conserve the waste heat and excess energy available such as solar radiation. Storage of latent heat using organic phase change materials (PCMs) offers greater energy storage density over a marginal melting and freezing temperature difference in comparison to inorganic materials. These favorable characteristics of organic PCMs make them suitable in a wide range of applications. These materials and their eutectic mixtures have been successfully tested and implemented in many domestic and commercial applications such as, building, electronic devices, refrigeration and air-conditioning, solar air/water heating, textiles, automobiles, food, …

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Effect Of Ion Concentration On Mechanosynthesis Of Carbonated Chlorapatite Nanopowders May 2015

Effect Of Ion Concentration On Mechanosynthesis Of Carbonated Chlorapatite Nanopowders

Faculty of Engineering University of Malaya

Carbonated chlorapatite nanopowders (n-CCAp) with different degrees of substitution were successfully synthesized by the one-step mechanochemical process. Results demonstrated that the formation of n-CCAp was influenced strongly by the carbonate content (x). From X-ray analysis, crystallite size, crystallinity degree, and unit cell volume of n-CCAp decreased significantly as carbonate content (x) increased from 0 to 2. Conversely, the lattice strain and the volume fraction of grain boundaries grew considerably. Microscopic analysis showed the average particle size of the synthesized powders was 15 +/- 10 nm. The influence of carbonate concentration on mechanosynthesis of pure n-CCAp utilizing a facile solid-state process …

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Dripping Dynamics Of Newtonian Liquids From A Tilted Nozzle May 2015

Dripping Dynamics Of Newtonian Liquids From A Tilted Nozzle

Faculty of Engineering University of Malaya

The dripping dynamics of Newtonian liquids emanating from an inclined nozzle is studied. The fluid viscosity mu flow rate Q, nozzle radius R, and inclination angle theta have been varied independently. The drop breakup times and the different modes of dripping have been identified using high speed imaging. A phase diagram showing the transition between the dripping modes for different theta is constructed in the (We, Ka) space, where We (Weber number) measures the relative importance of inertia to surface tension force and Ka (Kapitza number) measures the relative importance of viscous to surface tension forces. At low values of …

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Classification Of Electrocardiogram And Auscultatory Blood Pressure Signals Using Machine Learning Models May 2015

Classification Of Electrocardiogram And Auscultatory Blood Pressure Signals Using Machine Learning Models

Faculty of Engineering University of Malaya

In this paper, two real-world medical classification problems using electrocardiogram (ECG) and auscultatory blood pressure (Korotkoff) signals are examined. A total of nine machine learning models are applied to perform classification of the medical data sets. A number of useful performance metrics which include accuracy, sensitivity, specificity, as well as the area under the receiver operating characteristic curve are computed. In addition to the original data sets, noisy data sets are generated to evaluate the robustness of the classifiers against noise. The 10-fold cross validation method is used to compute the performance statistics, in order to ensure statistically reliable results …

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Fatigue Of Swollen Elastomers May 2015

Fatigue Of Swollen Elastomers

Faculty of Engineering University of Malaya

The compatibility of the properties of elastomer with conventional diesel fuel has made it favourable in many engineering applications. However, due to global energy insecurity issues, there is an urgent need to find alternative renewable sources of energy as replacements to conventional diesel. In this respect, biodiesel appears to be a promising candidate. Hence, research into the compatibility and fatigue characteristics of elastomers exposed to biodiesel becomes essential. The present paper introduces the first attempt to investigate the effect of different solvents on the fatigue of swollen elastomers. The filled nitrile rubbers are immersed in the palm biodiesel and conventional …

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Evaluation Of The Mechanical Properties Of Aa 6063 Processed By Severe Plastic Deformation May 2015

Evaluation Of The Mechanical Properties Of Aa 6063 Processed By Severe Plastic Deformation

Faculty of Engineering University of Malaya

In this study, the mechanical properties, including surface hardness, tensile strength, fatigue, and fretting fatigue behavior of AA 6063 processed by equal channel angular pressing as the most efficient severe shear plastic deformation (SPD) technique, were investigated. Following the SPD process, samples were subjected to heat treatment (HT), hard anodizing (HA), and a combination of HT and HA. Rotating-bending fretting fatigue tests were performed to explore the samples' response to the fretting condition. From the experimental fatigue and fretting fatigue tests, it was apparent that the SPD treatment had a positive effect on enhancing the fatigue and fretting fatigue lives …

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Influence Of Ultrasound Power On Acoustic Streaming And Micro-Bubbles Formations In A Low Frequency Sono-Reactor: Mathematical And 3d Computational Simulation May 2015

Influence Of Ultrasound Power On Acoustic Streaming And Micro-Bubbles Formations In A Low Frequency Sono-Reactor: Mathematical And 3d Computational Simulation

Faculty of Engineering University of Malaya

This paper aims at investigating the influence of ultrasound power amplitude on liquid behaviour in a low-frequency (24 kHz) sono-reactor. Three types of analysis were employed: (i) mechanical analysis of micro-bubbles formation and their activities/characteristics using mathematical modelling. (ii) Numerical analysis of acoustic streaming, fluid flow pattern, volume fraction of micro-bubbles and turbulence using 3D CFD simulation. (iii) Practical analysis of fluid flow pattern and acoustic streaming under ultrasound irradiation using Particle Image Velocimetry (Ply). In mathematical modelling, a lone micro bubble generated under power ultrasound irradiation was mechanistically analysed. Its characteristics were illustrated as a function of bubble radius, …

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Synergistic Sonoelectrochemical Removal Of Substituted Phenols: Implications Of Ultrasonic Parameters And Physicochemical Properties May 2015

Synergistic Sonoelectrochemical Removal Of Substituted Phenols: Implications Of Ultrasonic Parameters And Physicochemical Properties

Faculty of Engineering University of Malaya

The effects of ultrasonic conditions and physicochemical properties on the synergistic degradation in synthetic solution were investigated. A wide range of ultrasound frequencies, including 35, 170, 300, 500 and 700 kHz, and ultrasonic power densities, including 11.3, 22.5 and 31.5 W/L were used. It was revealed that the physical effect of ultrasound plays a major role in synergistic mechanism and 35 kHz was found to be the most effective frequency due to its more vigorous physical effect induced by high implosive energy released from collapse of cavitation bubbles. The highest ultrasonic power density (31.5 W/L) showed the highest synergy index …

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The Tribological And Electrochemical Behavior Of Hvof-Sprayed Cr3c2-Nicr Ceramic Coating On Carbon Steel May 2015

The Tribological And Electrochemical Behavior Of Hvof-Sprayed Cr3c2-Nicr Ceramic Coating On Carbon Steel

Faculty of Engineering University of Malaya

High Velocity Oxygen Fuel (HVOF) is an excellent approach to prepare a good, wear-resistant lamella of Chromium Carbide-Nickel Chrome (Cr3C2-NiCr) on carbon steel for high temperature application. This research investigates the effect of a thin, deposited layer of Cr3C2-NiCr on carbon steel in terms of wear and corrosion properties. The microstructure of the HVOF-sprayed Cr3C2-NiCr coating was characterized at each step by scanning electron microscopy. Wear testing was performed with a pin-on-disk tester. Wear weight loss was examined by applying different loads over a 9048.96 m sliding distance. Experimental results show that the wear resistance of the coated sample reduced …

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Coupling The Capabilities Of Different Complexing Agents Into Deep Eutectic Solvents To Enhance The Separation Of Aromatics From Aliphatics Apr 2015

Coupling The Capabilities Of Different Complexing Agents Into Deep Eutectic Solvents To Enhance The Separation Of Aromatics From Aliphatics

Faculty of Engineering University of Malaya

(Liquid + liquid) extraction of ethylbenzene from n-octane by using tetrabutylammonium bromide-based deep eutectic solvents (DESs) containing pyridine, ethylene glycol, or a mixture of both complexing agents was investigated at 25 degrees C and atmospheric pressure. The performance of each DES was determined from the distribution ratio and selectivity values calculated using experimental (liquid + liquid) equilibrium data of the ternary systems ethylbenzene + n-octane + DESs. The DES with only ethylene glycol had a high selectivity but a low distribution ratio, whereas the DES with only pyridine had a high distribution ratio but a low selectivity. For the other …

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Thermal Characteristic Reliability Of Fatty Acid Binary Mixtures As Phase Change Materials (Pcms) For Thermal Energy Storage Applications Apr 2015

Thermal Characteristic Reliability Of Fatty Acid Binary Mixtures As Phase Change Materials (Pcms) For Thermal Energy Storage Applications

Faculty of Engineering University of Malaya

The thermal characteristic reliability of two binary mixtures of fatty acid, myristic acid/palmitic acid/ sodium myristate (MA/PA/SM) and myristic acid/palmitic acid/sodium palmitate (MA/PA/SP), were investigated using a thermal cycling test setup for 0, 1000, 2000, 3000, and 3600 heating/cooling cycles. The changes in thermal properties and chemical bonding of both eutectic PCMs were measured using Differential Scanning Calorimetric (DSC) and Fourier Transform Infrared Spectroscopy (FT-IR) analyzer, respectively. MA/PA/SM and MA/PA/SP eutectic mixtures shows only minor changes in phase transition temperature (Tin, Ts) and in latent heat of fusion (ilk). Moreover, the chemical bonding structures of these eutectic PCMs show no …

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Evaluation Techniques And Improvements Of Adhesion Strength For Tin Coating In Tool Applications: A Review Apr 2015

Evaluation Techniques And Improvements Of Adhesion Strength For Tin Coating In Tool Applications: A Review

Faculty of Engineering University of Malaya

The adhesion between coating-substrate systems is an important factor in determining the performance and durability of coated engineering components. This paper reviews the microstructures and adhesion strength of titanium nitride (TiN) coating produced using two different processing methods: chemical vapor deposition and physical vapor deposition. Three methods to evaluate the adhesion strength of the coatings, namely the indentation test, laser spallation technique, and scratch test are presented and discussed in terms of their working principles, their advantages and disadvantages. The extrinsic and intrinsic factors influencing the adhesion strength of coating-substrate system, particularly for TiN coating, are also elaborated. The mechanisms …

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A Novel Lte Scheduling Algorithm For Green Technology In Smart Grid Apr 2015

A Novel Lte Scheduling Algorithm For Green Technology In Smart Grid

Faculty of Engineering University of Malaya

Smart grid (SG) application is being used nowadays to meet the demand of increasing power consumption. SG application is considered as a perfect solution for combining renewable energy resources and electrical grid by means of creating a bidirectional communication channel between the two systems. In this paper, three SG applications applicable to renewable energy system, namely, distribution automation (DA), distributed energy system-storage (DER) and electrical vehicle (EV), are investigated in order to study their suitability in Long Term Evolution (LTE) network. To compensate the weakness in the existing scheduling algorithms, a novel bandwidth estimation and allocation technique and a new …

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Prediction Of Speech Intelligibility Using A Neurogram Orthogonal Polynomial Measure (Nopm) Apr 2015

Prediction Of Speech Intelligibility Using A Neurogram Orthogonal Polynomial Measure (Nopm)

Faculty of Engineering University of Malaya

Sensorineural hearing loss (SNHL) is an increasingly prevalent condition, resulting from damage to the inner ear and causing a reduction in speech intelligibility. This paper proposes a new speech intelligibility prediction metric, the neurogram orthogonal polynomial measure (NOPM). This metric applies orthogonal moments to the auditory neurogram to predict speech intelligibility for listeners with and without hearing loss. The model simulates the responses of auditory-nerve fibers to speech signals under quiet and noisy conditions. Neurograms were created using a physiologically based computational model of the auditory periphery. A well-known orthogonal polynomial measure, Krawtchouk moments, was applied to extract features from …

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Effect Of N-Butanol And Diethyl Ether As Oxygenated Additives On Combustion-Emission-Performance Characteristics Of A Multiple Cylinder Diesel Engine Fuelled With Diesel-Jatropha Biodiesel Blend Apr 2015

Effect Of N-Butanol And Diethyl Ether As Oxygenated Additives On Combustion-Emission-Performance Characteristics Of A Multiple Cylinder Diesel Engine Fuelled With Diesel-Jatropha Biodiesel Blend

Faculty of Engineering University of Malaya

Jatropha biodiesel is considered as one of the most prospective renewable energy sources of Malaysia in recent years. Hence, an investigation was conducted for the improvement of jatropha biodiesel-diesel blend with the addition of 5-10% n-butanol and diethyl ether by vol. which are commonly known as oxygenated cold starting additive. Engine tests were conducted at variable speed, ranging from 1000 rpm to 3000 rpm at constant 80 N m torque on a 4-cylinder turbocharged indirect injection diesel engine. Engine performance parameters like brake specific fuel consumption, brake specific energy consumption, brake thermal efficiency and engine emissions like carbon monoxide, unburned …

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A Novel Lte Scheduling Algorithm For Green Technology In Smart Grid Apr 2015

A Novel Lte Scheduling Algorithm For Green Technology In Smart Grid

Faculty of Engineering University of Malaya

Smart grid (SG) application is being used nowadays to meet the demand of increasing power consumption. SG application is considered as a perfect solution for combining renewable energy resources and electrical grid by means of creating a bidirectional communication channel between the two systems. In this paper, three SG applications applicable to renewable energy system, namely, distribution automation (DA), distributed energy system-storage (DER) and electrical vehicle (EV), are investigated in order to study their suitability in Long Term Evolution (LTE) network. To compensate the weakness in the existing scheduling algorithms, a novel bandwidth estimation and allocation technique and a new …

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Prediction Of Unconfined Compressive Strength Of Pulverized Fuel Ash-Cement-Sand Mixture Apr 2015

Prediction Of Unconfined Compressive Strength Of Pulverized Fuel Ash-Cement-Sand Mixture

Faculty of Engineering University of Malaya

Recently, ground improvement has become much more feasible. Chemical stabilization is a quick and affordable approach to enhancing soil characteristics. An important avenue of research is discovering alternative materials for use in soil enhancement. Pulverized fuel ash (PFA), which is a waste byproduct of coal power plants, has been shown to reduce the environmental risks and costs involved in construction. In this study, a series of unconfined compressive tests were performed for various mixtures of cement, PFA, and sand; the tests considered both the curing period and the optimum moisture content (OMC). In addition, multiple variable linear regression was used …

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