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Articles 91 - 105 of 105
Full-Text Articles in Mechanical Engineering
Optimizing Cutting Parameters In Inclined End Milling For Minimum Surface Residual Stress - Taguchi Approach
Faculty of Engineering University of Malaya
End milling is an important and common machining operation because of its versatility and capability to produce various profiles and curved surfaces. Inclined end milling possesses the capability to translate in all 3 axes but can perform the cutting operation in only 2 of the 3 axes at a time. This research work focuses on investigating the effect of machined surface inclination angle, axial depth of cut, spindle speed and feed rate for better surface integrity in inclined end milling process utilizing titanium coated carbide ball end mill. An optimization method known as Taguchi optimization was used in order to …
Properties Of Zn-Bi Composite Coatings Prepared By Ionic Co-Discharge Deposition
Properties Of Zn-Bi Composite Coatings Prepared By Ionic Co-Discharge Deposition
Faculty of Engineering University of Malaya
Zn-Bi composite was synthesized by ionic co-discharge deposition and its properties were investigated. The results show that the Zn-Bi composite with the incorporation of Bi has a finer grain size than the pure Zn coating and improves the mechanical properties. The microhardness is increased by approximately two times simply by adding a small amount of Bi electrolyte into a Zn bath solution. A lower volume loss of the Zn-Bi composite coating compared with the pure Zn coating also indicates that the Zn-Bi coating has a better wear resistance. Link to Full-Text Articles : http://www.sciencedirect.com/science/article/pii/S1003632615635968
A Review Of Safety, Health And Environmental (She) Issues Of Solar Energy System
A Review Of Safety, Health And Environmental (She) Issues Of Solar Energy System
Faculty of Engineering University of Malaya
Solar energy is one of the cleanest forms of energy sources and considered as a green source of energy. Solar energy benefit ranges from low carbon emission, no fossil fuel requirement, long term solar resources, less payback time and other. However like other power generation sources, solar energy has also some Safety, Health and Environmental (SHE) concerns. This paper presents the overview of solar energy technologies and addresses the SHE impact of solar energy technologies to the sustainability of human activities. This paper will also recommend the possible ways to reduce the effect of potential hazards of widespread use of …
Review Of Improvements In Wire Electrode Properties For Longer Working Time And Utilization In Wire Edm Machining
Faculty of Engineering University of Malaya
Wire electrical discharge machining (WEDM) is an important technology, which demands high-speed cutting and high-precision machining to realize productivity and improved accuracy for manufacturing hard materials. WEDM has experienced explosive growth and complexity of equipment as well as rising demand for the basic process tool (the wire electrode). Greater taper angles, thicker workpieces, automatic wire threading, and long periods of unattended operation make the selection of the ideal wire a much more critical basis for achieving successful operation. This paper focuses on the evolution of EDM wire electrode technologies from using copper to the widely employed brass wire electrodes and …
Thermal Characteristic Of Sintered Ag-Cu Nanopaste For High-Temperature Die-Attach Application
Thermal Characteristic Of Sintered Ag-Cu Nanopaste For High-Temperature Die-Attach Application
Faculty of Engineering University of Malaya
In this work, thermal characteristic of silver-copper (Ag-Cu) nanopaste that consists of a mixture of nano-sized Ag and Cu particles and organic compounds meant for high-temperature die-attach application is reported. The Ag-Cu nanopaste was sintered at 380 degrees C for 30 min without the need of applying external pressure and the effect of Cu loading (20-80 wt%) on the thermal properties was investigated in against of pure Ag nanopaste and pure Cu nanopaste. The results showed the specific heat of sintered Ag-Cu nanopaste was increased as the loading of Cu increased. For thermal conductivity and coefficient of thermal expansion (CTE) …
Thermal And Dynamic Mechanical Properties Of Grafted Kenaf Filled Poly (Vinyl Chloride)/Ethylene Vinyl Acetate Composites
Faculty of Engineering University of Malaya
The effects of kenaf and poly (methyl methacrylate grafted kenaf on the thermal and dynamic mechanical properties of poly (vinyl chloride), PVC and ethylene vinyl acetate, EVA blends were investigated. The PVC/EVA/kenaf composites were prepared by mixing the grafted and ungrafted kenaf fiber and PVC/ EVA blend using HAAKE Rheomixer at a temperature of 150 degrees C and the rotor speed at 50 rpm for 20 min. The composites were subjected to Differential Scanning Calorimetric (DSC), Thermogravimetric analysis (TGA), dynamic mechanical analysis (DMA), Fourier transform infrared (FTIR) and Scanning Electron Microscopy (SEM) studies. The DSC data revealed that the crystallinity …
Investigating The Electrical Discharge Machining (Edm) Parameter Effects On Al-Mg2si Metal Matrix Composite (Mmc) For High Material Removal Rate (Mrr) And Less Ewr-Rsm Approach
Faculty of Engineering University of Malaya
Al-Mg2Si composite is a new group of metalmatrix composites (MMCs). Electrical discharge machining (EDM) is a nonconventional machining process for machining electrically conductive materials regardless of hardness, strength and temperature resistance, complex shapes, fine surface finish/textures and accurate dimensions. A copper electrode and oil-based dielectric fluid mixed with aluminum powder were used. The polarity of electrode was positive. Response surface methodology (RSM) was used to analyze EDM of this composite material. This research illustrates the effect of input variables (voltage, current, pulse ON time, and duty factor) on material removal rate (MRR), electrode wear ratio (EWR), and microstructure changes. The …
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 …
The Effects Of Calcium-To-Phosphorus Ratio On The Densification And Mechanical Properties Of Hydroxyapatite Ceramic
Faculty of Engineering University of Malaya
In this work, hydroxyapatite (HA) powders were synthesized using calcium hydroxide Ca(OH)(2) and orthophosphoric acid H3PO4 via wet chemical precipitation method in aqueous medium. Calcium-to-phosphorus (Ca/P) ratio was set to 1.57, 1.67, 1.87 that yield calcium-deficient HA, stoichiometric HA, and calcium-rich HA, respectively. These synthesized HA powders (having different Ca/P ratio) were characterized in terms of particle size and microstructural examination. Then, the densification and mechanical properties of the calcium-deficient HA, stoichiometric HA, and calcium-rich HA were evaluated from 1000 to 1350 degrees C. Experimental results have shown that no decomposition of hydroxyapatite phase was observed for stoichiometric HA (Ca/P …
The Effects Of Calcium-To-Phosphorus Ratio On The Densification And Mechanical Properties Of Hydroxyapatite Ceramic
Faculty of Engineering University of Malaya
In this work, hydroxyapatite (HA) powders were synthesized using calcium hydroxide Ca(OH)(2) and orthophosphoric acid H3PO4 via wet chemical precipitation method in aqueous medium. Calcium-to-phosphorus (Ca/P) ratio was set to 1.57, 1.67, 1.87 that yield calcium-deficient HA, stoichiometric HA, and calcium-rich HA, respectively. These synthesized HA powders (having different Ca/P ratio) were characterized in terms of particle size and microstructural examination. Then, the densification and mechanical properties of the calcium-deficient HA, stoichiometric HA, and calcium-rich HA were evaluated from 1000 to 1350 degrees C. Experimental results have shown that no decomposition of hydroxyapatite phase was observed for stoichiometric HA (Ca/P …
Modeling And Simulation Of Metal Organic Halide Vapor Phase Epitaxy (Mohvpe) Growth Chambe
Modeling And Simulation Of Metal Organic Halide Vapor Phase Epitaxy (Mohvpe) Growth Chambe
Faculty of Engineering University of Malaya
Over the last few decades, there was a substantial appeal on the growth of gallium-nitride (Ga-N) based alloy for high performance optoelectronic devices such as blue/violet laser diode, blue/white light emitting diode etc. In the recent years, there have been revolutionary changes in semiconductor field. Growth method for GaN-based film has been extensively explored, with success of thick film growth using halide vapor-phase epitaxy technique. The theoretical changes were attributed from the experimental results where modeling was vastly used for the purpose of design of equipment. This is because of the cost of the equipment and it is one of …
A Pair Of Bubbles' Rising Dynamics In A Xanthan Gum Solution: A Cfd Study
A Pair Of Bubbles' Rising Dynamics In A Xanthan Gum Solution: A Cfd Study
Faculty of Engineering University of Malaya
The motion and interaction of a bubble pair in a non-Newtonian fluid (xanthan gum solution) were numerically simulated using a volume of fluid (VOF) method, in which the continuous surface tension model and the power-law model were adopted to represent the surface tension and rheological properties of non-Newtonian fluids, respectively. The effects of the initial horizontal bubble interval, oblique alignment and rheological properties of non-Newtonian fluids on a pair of bubbles rising side-by-side are evaluated in this study. The results indicate that for the case with a non-dimensional initial horizontal bubble interval h* = 4.0, the interaction between the bubbles …
Influences Of Flame-Retardant Fillers On Fire Protection And Mechanical Properties Of Intumescent Coatings
Faculty of Engineering University of Malaya
A combination of acrylic binder and flame-retardant ingredients was used to synthesize the solvent-borne intumescent coatings designed for steel substrates. The influences of individual and various combinations of flame-retardant fillers on the fire protection and mechanical properties of the coatings were characterized by using Bunsen burner, thermogravimetric analysis, limiting oxygen index, field emission scanning electron microscopy, freeze thaw cycles, static immersion and pull-off type equipment. It was found that the combination of aluminium hydroxide (Al(OH)(3)) and titanium dioxide (TiO2) has significantly improved the fire protection, thermal stability and water resistance of the coating. This formulation had an LOI value of …
Comparative Evaluation Of The Blends Of Gas-To-Liquid (Gtl) Fuels And Biodiesels With Diesel At High Idling Conditions: An In-Depth Analysis On Engine Performance And Environment Pollutants
Faculty of Engineering University of Malaya
This study focuses on the physicochemical fuel characteristics and engine performance-emission features of three prospective alternative transportation fuels: Alexandrian laurel biodiesel (ALBD), jatropha biodiesel (JBD) and GTL fuel at high idling conditions. The blends of GTL fuel (G10, G20), JBD (J10, J20) and ALBD (AL10, AL20) with diesel had been investigated in a multi-cylinder diesel engine at different load-speed conditions. Analysis of the fuel properties showed a linear variation of the major fuel properties with an increase of alternative fuel quantity in the blends. Engine performance test results revealed an average decrease of brake specific fuel consumption (BSFC) (ca. 8.65-12.26%) …
Intermixing Reactions In Electrodeposited Cu/Sn And Cu/Ni/Sn Multilayer Interconnects During Room Temperature And High Temperature Aging
Faculty of Engineering University of Malaya
Current push for miniaturization and 3D packaging makes it important to understand reactions in interconnects with ultra small volume. In order to reduce processing time and to have more homogeneous interconnects, solder can be designed in a multilayer form with components layer thickness in the sub-micron or even nanometer range. In this work, reaction kinetics in multilayer interconnects consisting stacks of Cu/Sn/Cu and Cu/Ni/Sn/Ni/Sn deposited by electrodeposition were investigated at room temperature and 150 A degrees C. The progress of the reaction in the multilayers was monitored by using XRD, SEM and EDX. Results show that by inserting a 70 …