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Articles 1 - 13 of 13
Full-Text Articles in Mechanical Engineering
Multi-Response Analysis In The Processing Of Poly (Methyl Methacrylate) Nano-Fibres Membrane By Electrospinning Based On Response Surface Methodology: Fibre Diameter And Bead Formation
Faculty of Engineering University of Malaya
The fabrication of the nano-scale fine fibres from poly (methyl methacrylate) (PMMA)-DMF solution was completed using the electrospinning process. Significantly, fibre membranes with an average diameter of 95 (+/- 32) nm and bead number 11 (+/- 2) were successfully achieved. The extensive analysis of the distribution of fibre diameters and bead formation was performed using different needle gauge, collector distance, voltage, concentration, feed rate and molecular weight by observing images in FESEM after explanation of regression. A regression model was applied to realize the dominant factors on the responses, from this model, the molecular weight was excluded to successfully obtain …
Robust Control-Based Linear Bilateral Teleoperation System Without Force Sensor
Robust Control-Based Linear Bilateral Teleoperation System Without Force Sensor
Faculty of Engineering University of Malaya
Among the prevalent methods in linear bilateral teleoperation systems with communication channel time delays is to employ position and velocity signals in the control scheme. Utilizing force signals in such controllers significantly improves performance and reduces tracking error. However, measuring force signals in such cases, is one of the major difficulties. In this paper, a control scheme with human and environment force signals for linear bilateral teleoperation is proposed. In order to eliminate the measurement of forces in the control scheme, a force estimation approach based on disturbance observers is applied. The proposed approach guarantees asymptotic estimation of constant forces, …
Optimizing The Robot Arm Movement Time Using Virtual Reality Robotic Teaching System
Optimizing The Robot Arm Movement Time Using Virtual Reality Robotic Teaching System
Faculty of Engineering University of Malaya
Robots play an important role in performing operations such as welding, drilling and screwing parts in manufacturing. Optimizing the robot arm movement time between different points is an important task which will minimize the make-span and maximize the production rate. But robot programming is a complex task whereby the user needs to teach and control the robot in order to perform a desired action. In order to address the above problem, an integrated 3-dimensional (3D) simulation software and virtual reality (VR) system is developed to simplify and speed up tasks and therefore enhance the quality of manufacturing processes. This system …
Ceiba Pentandra, Nigella Sativa And Their Blend As Prospective Feedstocks For Biodiesel
Ceiba Pentandra, Nigella Sativa And Their Blend As Prospective Feedstocks For Biodiesel
Faculty of Engineering University of Malaya
There are more than 350 oil-bearing crops identified as potential sources for biodiesel production around the globe. The wide range of available feedstocks for biodiesel production represents one of the most significant factors for producing biodiesel. The current research work is carried out on fuel properties of biodiesel prepared from the non-edible oils of Ceiba pentandra, Nigella sativa and their mixture. N. sativa is believed to be investigated for the first time as a biodiesel feedstock while C. pentandra has been reported recently in few studies. Owing to higher acid value, acid-esterification and alkali-transesterification processes have been carried out for …
Effect Of Tool Rotational Speed On Force Generation, Microstructure And Mechanical Properties Of Friction Stir Welded Al-Mg-Cr-Mn (Aa 5052-O) Alloy
Faculty of Engineering University of Malaya
Friction stir welding (FSW) between 3 mm thick AA 5052-O aluminum alloy plates was investigated in the present study. Different welded specimens were produced by employing a constant tool traverse speed of 120 mm/min and by varying rotating speeds from 800 to 3000 rpm. The welded joints were characterized by its appearances, microstructural and mechanical properties at room temperature. The measurement of different forces acted on the tool during the FSW of AA 5052-O plates provided a significant insight to determine the quality of the welded joints. From the appearances of the welded joints it was evident that, except the …
Fuzzy Logic Based Model For Predicting Surface Roughness Of Machined Al-Si-Cu-Fe Die Casting Alloy Using Different Additives-Turning
Faculty of Engineering University of Malaya
This paper presents a fuzzy logic artificial intelligence technique for predicting the machining performance of Al-Si-Cu-Fe die casting alloy treated with different additives including strontium, bismuth and antimony to improve surface roughness. The Pareto-ANOVA optimization method was used to obtain the optimum parameter conditions for the machining process. Experiments were carried out using oblique dry CNC turning. The machining parameters of cutting speed, feed rate and depth of cut were optimized according to surface roughness values. The results indicated that a cutting speed of 250 m/min, a feed rate of 0.05 mm/rev, and a depth of cut of 0.15 mm …
Investigating The Machinability Of Al-Si-Cu Cast Alloy Containing Bismuth And Antimony Using Coated Carbide Insert
Faculty of Engineering University of Malaya
Surface roughness and cutting force are two key measures that describe machined surface integrity and power requirement evaluation, respectively. This investigation presents the effect of melt treatment with addition of bismuth and antimony on machinability when turning Al-11% Si-2% Cu alloy. The experiments are carried out under oblique dry cutting conditions using a PVD TIN-coated insert at three cutting speeds of 70, 130 and 250 m/min, feed rates of 0.05, 0.1, 0.15 mm/rev, and 0.05 mm constant depth of cut. It was found that the Bi-containing workpiece possess the best surface roughness value and lowest cutting force due to formation …
Pangium Edule Reinw: A Promising Non-Edible Oil Feedstock For Biodiesel Production
Pangium Edule Reinw: A Promising Non-Edible Oil Feedstock For Biodiesel Production
Faculty of Engineering University of Malaya
Biodiesel production from non-edible feedstocks is currently drawing much attention due to legitimate concerns about the effects of using edible oil for fuel. Pangium edule Reinw is a non-edible feedstock. Pangium is a tall tree native to the Micronesia, Melanesia and the mangrove swamps of South-East Asia. In this study, biodiesel production and characterization from P. edule oil was reported. The seeds were obtained from Bogor, Indonesia. The oil was found to have an acid value of 19.62 mg KOH/g oil. Therefore, a two-step acid-base-catalysed transesterification was used to produce biodiesel. This was followed by evaluating the physical and chemical …
Theoretical Modelling Of Momentum Transfer Function Of Bi-Disperse Porous Media
Theoretical Modelling Of Momentum Transfer Function Of Bi-Disperse Porous Media
Faculty of Engineering University of Malaya
The aim of this paper is to obtain the momentum transfer coefficient between the two phases, denoted by f and p, occupying a bi-disperse porous medium by mapping the available experimental data to the theoretical model proposed by Nield and Kuznetsov [1]. Data pertinent to plate-fin heat exchangers, as bi-disperse porous media, were used. The measured pressure drops for such heat exchangers are then used to give the overall permeability which is linked to the porosity and permeability of each phase as well as the interfacial momentum transfer coefficient between the two phases. Accordingly, numerical values are obtained for the …
Basic Effects Of Pulp Refining On Fiber Properties-A Review
Basic Effects Of Pulp Refining On Fiber Properties-A Review
Faculty of Engineering University of Malaya
The requirement for high quality pulps which are widely used in paper industries has increased the demand for pulp refining (beating) process. Pulp refining is a promising approach to improve the pulp quality by changing the fiber characteristics. The diversity of research on the effect of refining on fiber properties which is due to the different pulp sources, pulp consistency and refining equipment has interested us to provide a review on the studies over the last decade. In this article, the influence of pulp refining on structural properties i.e., fibrillations, fine formation, fiber length, fiber curl, crystallinity and distribution of …
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 …