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Articles 31 - 60 of 92
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Sintering Behaviour Of Natural Porous Hydroxyapatite Derived From Bovine Bone
Sintering Behaviour Of Natural Porous Hydroxyapatite Derived From Bovine Bone
Faculty of Engineering University of Malaya
The aim of this research is to study the properties of natural porous hydroxyapatite developed from bovine bone through a sintering process. Bovine bone samples were prepared and sintered in an air atmosphere at different temperatures ranging from 600 degrees C to 1000 degrees C. The sintered bodies were characterized to determine the phases present, bulk density, Ca/P ratio and Vickers hardness. In addition, the microstructural evolution of the sintered porous bodies was also examined. The results revealed that the thermal stability of the HA matrix was not disrupted and that all of the sintered bodies exhibited phase pure HA. …
Sintering Behaviour Of Natural Porous Hydroxyapatite Derived From Bovine Bone
Sintering Behaviour Of Natural Porous Hydroxyapatite Derived From Bovine Bone
Faculty of Engineering University of Malaya
The aim of this research is to study the properties of natural porous hydroxyapatite developed from bovine bone through a sintering process. Bovine bone samples were prepared and sintered in an air atmosphere at different temperatures ranging from 600 degrees C to 1000 degrees C. The sintered bodies were characterized to determine the phases present, bulk density, Ca/P ratio and Vickers hardness. In addition, the microstructural evolution of the sintered porous bodies was also examined. The results revealed that the thermal stability of the HA matrix was not disrupted and that all of the sintered bodies exhibited phase pure HA. …
Spotlight On Available Optical Properties And Models Of Nanofluids: A Review
Spotlight On Available Optical Properties And Models Of Nanofluids: A Review
Faculty of Engineering University of Malaya
Optical characteristics besides unique thermo-physical properties of nanoparticles have encouraged researchers to use nanofluids in solar energy collectors or reservoirs as electromagnetic wave absorbing media. Recently, different analyses and approaches have been proposed by researchers. However, the appropriate electro-magnetic phenomenon of nanofluids is not established till date because of the complex dependence between nanoparticles and base fluids. In this work, optical properties of nanofluids are discussed on the basis of published data; mostly used models are presented along with their limitations and applications. (C) 2014 Elsevier Ltd. All rights reserved. Link to Full-Text Articles : http://www.sciencedirect.com/science/article/pii/S1364032114009411
Simulation Of Unsteady Heat And Mass Transport With Heatline And Massline In A Partially Heated Open Cavity
Faculty of Engineering University of Malaya
A computational work is performed to investigate the transient heat and mass transfer inside a ventilated enclosure. The enclosure has two ventilation ports as inlet and outlet. Three different configurations are tested according to location of outlet ports while location of inlet port is fixed. In case 1, the outlet port is located on the top of the left vertical wall, in case 2 at the right and case 3 at the middle of the ceiling. Finite element method is employed to solve the governing equations of flow, heat and mass transfer. Also, the heatline and massline techniques are used …
Electrospinning Of Polymethyl Methacrylate Nanofibers: Optimization Of Processing Parameters Using The Taguchi Design Of Experiments
Faculty of Engineering University of Malaya
The effects of polymer concentration and electrospinning parameters on the diameter of electrospun polymethyl methacrylate (PMMA) fibers were experimentally investigated. It was also studied how the controlled factors would affect the output with the intention of finding the optimal electrospinning settings in order to obtain the smallest PMMA fiber diameter. Subsequently the solution feed rate, needle gauge diameter, supply voltage, polymer concentration and tip-to-collector distance were considered as the control factors. To achieve these aims, Taguchi's mixed-level parameter design (L-18) was employed for the experimental design. Optimal electrospinning conditions were determined using the signal-to-noise (S/N) ratio that was calculated from …
A New Hybrid Support Vector Machine-Wavelet Transform Approach For Estimation Of Horizontal Global Solar Radiation
Faculty of Engineering University of Malaya
In this paper, a new hybrid approach by combining the Support Vector Machine (SVM) with Wavelet Transform (WT) algorithm is developed to predict horizontal global solar radiation. The predictions are conducted on both daily and monthly mean scales for an Iranian coastal city. The proposed SVM-WT method is compared against other existing techniques to demonstrate its efficiency and viability. Three different sets of parameters are served as inputs to establish three models. The results indicate that the model using relative sunshine duration, difference between air temperatures, relative humidity, average temperature and extraterrestrial solar radiation as inputs shows higher performance than …
Physicochemical Characterization And Thermal Behavior Of Biodiesel And Biodiesel–Diesel Blends Derived From Crude Moringa Peregrina Seed Oil
Faculty of Engineering University of Malaya
Moringaceae is a monogeneric family with a single genus i.e. Moringa. This family includes 13 species. All these species are known as medicinal, nutritional and water purification agents. This study reports, for the first time, on characterization of the biodiesel derived from crude Moringa peregrina seed oil and its blends with diesel. The crude oil was converted to biodiesel by the transesterification reaction, catalyzed by potassium hydroxide. High ester content (97.79%) was obtained. M. peregrina biodiesel exhibited high oxidative stability (24.48 h). Moreover, the major fuel properties of M. peregrina biodiesel conformed to the ASTM D6751 standards. However, kinematic viscosity …
Performance Dependence Of Thermosyphon On The Functionalization Approaches: An Experimental Study On Thermo-Physical Properties Of Graphene Nanoplatelet-Based Water Nanofluids
Faculty of Engineering University of Malaya
Graphene Nanoplatelets (GNP) were stably dispersed in aqueous media by covalent and non-covalent functionalization. Covalent functionalization was performed by a rapid microwave-assisted approach. Surface functionality groups and morphology of acid-treated GNP were analyzed by Fourier transform infrared spectroscopy and transmission electron microscopy. The GNP-based water nanofluids were then prepared with different concentrations of GNP to evaluate the thermo-physical and rheological properties. It was found that the rheological and thermo-physical properties of all treated samples were significantly enhanced compared to the pure water. The amount of enhancement also increased as the weight concentration increased. Thermo-physical results also confirmed that the thermal …
Tio2 Nanotube Coating On Stainless Steel 304 For Biomedical Applications
Tio2 Nanotube Coating On Stainless Steel 304 For Biomedical Applications
Faculty of Engineering University of Malaya
The present study describes the anodic growth of TiO2 nanotube thin layer on stainless steel 304 in ethylene glycol/water/ammonium fluoride electrolyte. In this regard, pure titanium was coated on stainless steel 304 substrates by a physical vapor deposition magnetron sputtering (PVDMS) technique. The adhesion strength of the coating to the substrate was investigated. TiO2 nanotubes were generated on the top of the Ti coated substrates by means of anodization technique at a 25 V potential and times of 20, 40, and 60 min in an ammonium fluoride electrolyte solution. The anodized Ti-coated samples were heat-treated at 280 degrees C, 430 …
Using Local Stiffness Indicator To Examine The Effect Of Honeycombs On The Flexural Stiffness Of Reinforced Concrete Beams
Faculty of Engineering University of Malaya
Experimental modal analysis was performed on RC beams with honeycombs. The mode shapes were extracted, and the eigenvectors were used in determining the mode shape equations using nonlinear regression. The equation used in the regression was the generalized solution of transverse vibration of a Bernoulli-Euler prismatic beam. By utilizing the regressed phase variable, the global flexural stiffness was evaluated. It was observed that the global stiffness dropped with increasing volumes of the honeycombs in the beam. The results were compared with values computed using the secant modulus from the load-deflection plot obtained upon loading at each load stage and the …
Fabrication And Characterization Of Poly(Octanediol Citrate)/Gallium-Containing Bioglass Microcomposite Scaffolds
Faculty of Engineering University of Malaya
Bone can be affected by osteosarcomae requiring surgical excision of the tumor as part of the treatment regime. Complete removal of cancerous cells is difficult and conventionally requires the removal of a margin of safety around the tumor to offer improved patient prognosis. This work considers a novel series of composite scaffolds based on poly(octanediol citrate) (POC) impregnated with gallium-based bioglass microparticles for possible incorporation into bone following tumor removal. The objective of this research was to fabricate and characterize these scaffolds and subsequently report on their mechanical and biological properties. The porous microcomposite scaffolds with various concentrations of bioglass …
An Updated Overview Of Diamond-Like Carbon Coating In Tribology
An Updated Overview Of Diamond-Like Carbon Coating In Tribology
Faculty of Engineering University of Malaya
During the last two decades, the industry (including scientists) has focused on diamond-like carbon (DLC) coating because of its wide range of application in various fields. This material has numerous applications in mechanical, electrical, tribological, biomedical, and optical fields. Severe friction and wear in some machine parts consumes high amount of energy, which makes the process energy inefficient. Thus, DLC coating can be an effective means to lower the friction and wear rate. Some important process variables that affect the tribological characteristics of DLC coating are adhesion promoter intermediate layer, substrate surface roughness, hydrogen incorporation or hydrogen non involvement, and …
Dissimilar Friction Stir Welding Between Polycarbonate And Aa 7075 Aluminum Alloy
Dissimilar Friction Stir Welding Between Polycarbonate And Aa 7075 Aluminum Alloy
Faculty of Engineering University of Malaya
In this paper, the effects of process parameters, such as the tool rotational and traverse speeds, on temperature evolution and the microstructural and mechanical properties of dissimilar friction stir welding between 3 mm thick AA 7075 aluminum alloy and polycarbonate (PC) plates were investigated. The tool rotational and traverse speeds were varied from 3 000 to 3 500 rpm and 50 to 150 mm min(-1), respectively. The joint fabricated at 3 250 rpm and 100 mm min(-1) yielded a highest tensile load of 586 N. Microstructural analysis of the stir zone revealed an interlock phenomenon, the transportation of AA 7075 …
A Glass Polyalkenoate Cement Carrier For Bone Morphogenetic Proteins
A Glass Polyalkenoate Cement Carrier For Bone Morphogenetic Proteins
Faculty of Engineering University of Malaya
This work considers a glass polyalkenoate cement (GPC)-based carrier for the effective delivery of bone morphogenetic proteins (BMPs) at an implantation site. A 0.12 CaO-0.04 SrO-0.36 ZnO-0.48 SiO2 based glass and poly(acrylic acid) (PAA, Mw 213,000) were employed for the fabrication of the GPC. The media used for the water source in the GPC reaction was altered to produce a series of GPCs. The GPC liquid media was either 100 % distilled water with additions of albumin at 0, 2, 5 and 8 wt% of the glass content, 100 % formulation buffer (IFB), and 100 % BMP (150 mu g …
Heat Transfer Coefficient Of Flowing Wood Pulp Fibre Suspensions To Monitor Fibre And Paper Quality
Heat Transfer Coefficient Of Flowing Wood Pulp Fibre Suspensions To Monitor Fibre And Paper Quality
Faculty of Engineering University of Malaya
Heat transfer measurements were obtained for a range of suspensions of wood pulp fibre flowing through a pipeline. Data were generated over a selected range of flow rates and temperatures from a specially built flow loop. It was found that the magnitude of the heat transfer coefficient was above water at equivalent experimental conditions at very low fibre concentrations, but progressively decreased until it was below water at slightly higher concentrations. It was found that the heat transfer was affected by varying fibre properties, such as fibre length, fibre flexibility, fibre chemical and mechanical treatment, the variation of fibres from …
Soft Computing Methodologies For Estimation Of Bridge Girder Forces With Perforations Under Tsunami Wave Loading
Faculty of Engineering University of Malaya
Tsunamis pose a great threat to coastal infrastructures. Bridges without adequate provisions for earthquake and tsunami loading generally are vulnerable when a tsunami occurs. During the last two disastrous tsunami events (i.e., the tsunami in the Indian Ocean and the tsunami that struck Japan), many bridges were damaged by the waves created by the tsunamis. In this paper, in order to address this crucial problem, we used soft computing techniques to design and develop a process that simulates the effects of perforations in the girders of bridges on reducing the forces applied on the bridge when a tsunami occurs. Soft …
Effect Of Microwave Frequency On Dielectric Properties Of Oil Palm Shell (Ops) And Ops Char Synthesized By Microwave Pyrolysis Of Ops
Faculty of Engineering University of Malaya
Microwave heating is considered to be a potential, efficient and fast method for thermal treatment of biomass. Therefore, elemental understanding of dielectric properties of biomass is necessary before irradiating it with microwave radiations. Dielectric properties along with penetration depth, relaxation time and static permittivity of oil palm shell COPS) and OPS char were investigated in the frequency ranging between 0.5 and 20 GHz at room temperature. At low frequencies, dielectric constant of UPS was higher than that of UPS char while at higher frequencies, vice versa is observed. Penetration depth for UPS char was higher than that of UPS at …
New Method For Distance-Based Close Following Safety Indicator
New Method For Distance-Based Close Following Safety Indicator
Faculty of Engineering University of Malaya
Objective: The increase in the number of fatalities caused by road accidents involving heavy vehicles every year has raised the level of concern and awareness on road safety in developing countries like Malaysia. Changes in the vehicle dynamic characteristics such as gross vehicle weight, travel speed, and vehicle classification will affect a heavy vehicle's braking performance and its ability to stop safely in emergency situations. As such, the aim of this study is to establish a more realistic new distance-based safety indicator called the minimum safe distance gap (MSDG), which incorporates vehicle classification (VC), speed, and gross vehicle weight (GVW). …
Fuzzy Logic-Based Approach To Investigate The Novel Uses Of Nano Suspended Lubrication In Precise Machining Of Aerospace Al Tempered Grade 6061
Faculty of Engineering University of Malaya
Temper-grade aluminum alloy Al-6061-T6 is commonly used for many engineering purposes owing to its superior mechanical properties. Due to the practical importance, machining Al-6061-T6 alloy is crucial for different applications. The development of computer numerical control (CNC) of milling machines is in progress by researchers worldwide for its noteworthy advantages. The quality of machining determines the product's appearance, function and reliability. Appropriate lubrication at the machining zone improves the tribological characteristic of Al-6061-T6 alloy, leading to higher product quality. For reasons of ambiguity during machining, the soft computing technique is chosen to predict the output. In this particular research scope, …
Study On Coarsening Of Ag3sn Intermetallic Compound In The Fe-Modified Sn-1ag-0.5cu Solder Alloys
Study On Coarsening Of Ag3sn Intermetallic Compound In The Fe-Modified Sn-1ag-0.5cu Solder Alloys
Faculty of Engineering University of Malaya
The present study focuses on coarsening of Ag3Sn intermetallic compound in the Sn-1Ag-0.5Cu and Fe-modified Sn-1Ag-0.5Cu solder alloy. The investigations showed that the Ag3Sn intermetallics coarsened rapidly in the Sn-1Ag-0.5Cu solder alloy whereas the Ag3Sn intermetallics were found to be quite stable in the Fe-modified Sn-1Ag-0.5Cu solder alloy. The lattice strain in the Ag3Sn intermetallics and the blocking effect on Ag diffusivity in Sn matrix suggested the possible mechanisms for the coarsening suppression of the Ag3Sn intermetallics in the Fe-modified solder alloy. (C) 2014 Elsevier B.V. All rights reserved. Link to Full-Text Articles : http://www.sciencedirect.com/science/article/pii/S0925838814024621
Alternative Methods To Determine The Elastoplastic Properties Of Sintered Hydroxyapatite From Nanoindentation Testing
Faculty of Engineering University of Malaya
This study introduces alternative methods to determine the elastoplastic properties of bovine-derived Hydroxyapatite (HA) porous bone graft through a set of nanoindentation tests with a Berkovich indenter. Generally, experimental data obtained from nanoindentation tests are force displacement, hardness and elastic modulus. However, to determine plastic properties such as strength coefficient and work hardening exponent of bovine HA, analytical or inverse finite element models are required. In this paper, the effect of sintering temperature on these properties of HA is studied for the range of 1000-1400 degrees C. The direct and inverse Finite Element (FE) simulation models for nanoindentation tests were …
Assessment Of A Planar Inclusion In A Solid Cylinder
Assessment Of A Planar Inclusion In A Solid Cylinder
Faculty of Engineering University of Malaya
As a planar inclusion in a solid cylinder can lead to a catastrophic failure of a whole structure, relevant studies on evaluating quantitative fracture values are always sought for supporting the investigations. In line with the use of nondestructive evaluation technique for quantifying the embedded defects in structures, relevant research findings would be usable to contribute to the structural integrity analyses. It is also intended to have the possibility of the use of the data in a preliminary structural design stage. Since the complexity of the experimental setup for evaluating a planar inclusion in a solid component, numerical modeling is …
Buoyancy Induced Heat Transfer Deterioration In Vertical Concentric And Eccentric Annuli
Buoyancy Induced Heat Transfer Deterioration In Vertical Concentric And Eccentric Annuli
Faculty of Engineering University of Malaya
Turbulent convection heat transfer of upward fluid flows in vertical annular channels with uniformly heated inner wall and adiabatic outer wall is investigated numerically. Two concentric geometries with outer-to-inner diameter ratios of 2.4 and 3 as well as two eccentric geometries with identical outer-toinner diameter ratio of 2.4 and eccentricities of 0.25 and 0.5 are investigated. Heat transfer deterioration, similar to that of a circular pipe, is observed. The range of buoyancy parameter, over which deterioration is observed, is close to that of circular pipes. Moreover, it is observed that when the value of eccentricity increases, the deterioration phenomenon becomes …
Biodiesel Production, Characterization, Diesel Engine Performance, And Emission Characteristics Of Methyl Esters From Aphanamixis Polystachya Oil Of Bangladesh
Faculty of Engineering University of Malaya
This paper presents the prospect of biodiesel derived from Aphanamixis polystachya oil in diesel engine. The study deals with the physicochemical properties of A. polystachya methyl ester (APME) and its blends followed by evaluation of performance and emission characteristics of APME5 and APME10 in a multi-cylinder diesel engine. It has been observed that the properties of biodiesel and its blends are compatible with the ASTM D6751 and ASTM D7467 standards, respectively. It was found that, APME5 and APME10 showed an average 0.9% and 1.81% reduction in torque and 0.9% and 2.1% reduction in brake power (BP), and 0.87% and 1.78% …
Measuring Of Positioning, Circularity And Static Errors Of A Cnc Vertical Machining Centre For Validating The Machining Accuracy
Faculty of Engineering University of Malaya
A CNC machine tool performance depends on the machine accuracy status which is very important to determine the end product compliance to the specification. The accuracy of the machine can be measured and analyzed; hence the errors' impact can be predicted on a workpiece. This paper presents three types of accuracy tests performed on a CNC Vertical Machining Centre, how the accuracy status affect the end product quality and what are the corrective actions to be taken. First, the laser test to determine the linear positioning accuracy, second the ball bar test to determine the circularity accuracy and third, the …
Cutting Force-Based Adaptive Neuro-Fuzzy Approach For Accurate Surface Roughness Prediction In End Milling Operation For Intelligent Machining
Faculty of Engineering University of Malaya
End milling is one of the most common metal removal operations encountered in industrial processes. Product quality is a critical issue as it plays a vital role in how products perform and is also a factor with great influence on manufacturing cost. Surface roughness usually serves as an indicator of product quality. During cutting, surface roughness measurement is impossible as the cutting tool is engaged with the workpiece, chip and cutting fluid. However, cutting force measurement is easier and could be used as an indirect parameter to predict surface roughness. In this research work, a correlation analysis was initially performed …
Effective Utilization Of Excess Energy In Standalone Hybrid Renewable Energy Systems For Improving Comfort Ability And Reducing Cost Of Energy: A Review And Analysis
Faculty of Engineering University of Malaya
One of the features that characterize renewable energy sources is their variability and intermittency. Intermittency covers both the predictable and unpredictable variations of their power outputs and uncertainty in the power availability. To overcome the drawback of intermittency, special design considerations should be taken into account. These additional design considerations increases the overall cost of the renewable energy systems. Adding storage system and/or backup source to the renewable sources is one of the measures used to guarantee the continuity of power supply to the loads, and therefore improve the reliability of the renewable energy systems. The operation of renewable energy …
An Experimental And Numerical Investigation Of Heat Transfer Enhancement For Graphene Nanoplatelets Nanofluids In Turbulent Flow Conditions
Faculty of Engineering University of Malaya
In this paper, both experimental and numerical studies have been performed on the turbulent heat transfer of the graphene nanoplatelets nanofluids in a horizontal stainless steel tube that was subjected to a uniform heat flux at its outer surface. An experimental investigation was done to evaluate the heat transfer characteristics and the pressure drop of a graphene nanoplatelet (GNP) nanofluid and in numerical study, the finite volume method with standard k-epsilon turbulence model is employed to solve the continuity, momentum, energy and turbulence equations in three dimensional domains. The thermal conductivity and viscosity of the GNP nanofluids at concentrations of …
Fabrication And Characterization Of Microstacked Pzt Actuator For Mems Applications
Fabrication And Characterization Of Microstacked Pzt Actuator For Mems Applications
Faculty of Engineering University of Malaya
A microstacked PZT actuator of dimensions 8 mmx 0.8 mm x 0.4 mm and capable of 2.3-mu m actuation under a voltage of 100 V was fabricated and characterized. This actuator was then integrated into a silicon microstage with dimensions of 20 mm x 20 mm x 0.4 mm requiring actuation by a miniaturized actuator. The microstage was designed containing a Moonie amplification mechanism in order to further amplify the actuation of the stacked PZT actuator. Experimental characterization of the microstage performance indicated that the combination of a stacked PZT actuator with the Moonie amplification mechanism was successful in enabling …
Impact Of In Situ Physical And Chemical Cleaning On Pvdf Membrane Properties And Performances
Impact Of In Situ Physical And Chemical Cleaning On Pvdf Membrane Properties And Performances
Faculty of Engineering University of Malaya
Appropriate selection of cleaning agent is an important factor to achieve a better cleaning efficiency and this topic has become an ongoing discussion. This work assesses the impacts of sodium hydroxide (NaOH) and sodium hypochlorite (NaOCl) aqueous solution towards polyvinylidene fluoride (PVDF) stability at the typical concentrations used in membrane cleaning. The cleaned membranes were characterised using held emission scanning electron microscopy (FESEM), Fourier transform infrared (FTIR), pure water flux measurement, contact angle, protein retention and tensile testing. Membrane cleaned at elevated temperature and higher concentration presented a higher water flux than the virgin membrane which can be a worrying …