Entity

Time filter

Source Type

Gombak, Malaysia

Chee C.Y.,University of Malaya | Yahya R.Y.,University of Malaya | Li G.,Kulliyyah of Engineering
Journal of Nano Research | Year: 2013

Polylactides (PLA) based composite films modified with nanoclay content ranges from 0-30 wt% were fabricated using solvent casting method and the mechanical properties, water vapor permeability, oxygen barrier, thermal stability and optical properties were studied. The study showed that the addition of up to 15 wt% of clay has caused a significant improvement of tensile strength of the PLA/nanoclay composite film. However, the further increasing of nanoclay content of >15 wt% of nanoclay has caused a significant reduction in tensile, elongation at break and optical properties of PLA matrix. Both the oxygen and water permeability of the PLA/nanoclay composite film decrease with the increasing of nanoclay contents. Greater water barrier properties would be achieved if the high nanoclay contents of 10-30 wt% were dispersed homogenous within the PLA matrix. The addition of nanoclay greater than 10 wt% affected the appearance of the film (i.e. increasing the haze and ΔE). Thermal analysis result has proved that the melting temperature, crystallization temperature and glass transition temperature of the composite film only slightly affected by the addition of nanoclay due to the immobilization polymer chain in the composite film. © (2013) Trans Tech Publications, Switzerland. Source


Sulaiman S.A.,University Technology of MARA | Amin A.N.,Kulliyyah of Engineering
IOP Conference Series: Materials Science and Engineering | Year: 2015

In machining operations, chatter is undesirable due to its adverse effects on the product quality, operation cost, machining accuracy and machine tool life. It is also responsible for reducing output. Chatter is a self-excitation phenomenon occurring in machine tools, in which the cutting process tends to lower the damping capacity of the machine structural components ending in an unstable behavior of the system. Chatter arises due to resonance when the vibrations of the instability of chip formation and the natural vibration modes of the machine-system components coincide. This paper focuses on the influence of damping coefficient from permanent magnets on chip serration frequency as an approach of minimizing chatter in end milling of Titanium alloy (Ti6Al4V). The method consists of two ferrite permanent magnet bars (dimensions: 1″ × 6″ × 3″), mounted 5mm from the cutting tool using a specially designed fixture which provided a uniform magnetic field of 2500-2700 Gausses. A titanium alloy Ti6Al4V block was then end milled using uncoated WC-Co inserts. A sequence of 15 experimental runs was conducted based on a small Central Composite Design (CCD) model in Response Surface Methodology (RSM). The primary (independent) parameters were: cutting speed, feed, and depth of cut. The data acquisition system comprised a vibration sensor (accelerometer) and a signal conditioning unit was used to measure the vibration data. The resultant vibrations were then analyzed using the DASYLab 5.6 software. Machining tests were conducted for two different conditions - with and without the application of magnets. Scanning Electron Microscope (SEM) was used to measure the chip segmentations. The SEM analysis of chip serrations demonstrated that the chip serration frequency were more stable while cutting under the presence of permanent magnets due to lower intensity of chatter. Source


Sulaiman S.A.,University Technology of MARA | Amin A.K.M.N.,Kulliyyah of Engineering
Applied Mechanics and Materials | Year: 2014

Machining of metals is generally accompanied by a violent relative vibration between work and tool, known as chatter. Chatter arises due to resonance when the vibrations of the instability of chip formation and the natural vibration modes of the machine-system components coincide. This paper focuses on a novel approach of minimizing chatter in end milling of Titanium alloy (Ti6Al4V) under magnetic field from permanent magnets. The method consists of two ferrite permanent magnet bars (dimensions: 1″ × 6″ × 3″), mounted 5mm from the cutting tool using a specially designed fixture, to provide a uniform magnetic field of 2500-2700 Gausses (approximately). A titanium alloy Ti6Al4V block was then end milled using uncoated WC-Co inserts.The experiments were designed using the Design Expert software with three independent variables; cutting speed, feed, and depth of cut. Machining tests were conducted for two different conditions - with and without the application of magnets. Scanning Electron Microscope (SEM) was used to measure the chip segmentations.The SEM analysis of chip serrations demonstrated that the chip formations were more stable while cutting under the presence of permanent magnets due to lower intensity of chatter. © (2014) Trans Tech Publications, Switzerland. Source


Mohd Noor N.M.,University Technology of MARA | Ahmad S.,Kulliyyah of Engineering | Sidek S.N.,Kulliyyah of Engineering
Applied Mechanics and Materials | Year: 2014

The aim of this study is to perform the experimental verification on the fuzzy-based control designed for wheelchair motion. This motion control based on the eye movement signals using electrooculograhphy (EOG) technique. The EOG is a technique to acquire the eye movement data from a person, i.e tetraplegia, which the data obtained, can be used as a main communication tool. This study is about the implementation of the designed controller using PD-type fuzzy controller and tested on the hardware of the wheelchair system using the eye movement signal obtained through EOG technique as the motion input references. The results obtained show that the PD-type fuzzy logic controller designed has successfully managed to track the input reference for linear motion set (forward and backward direction) by the EOG signal. © (2014) Trans Tech Publications, Switzerland. Source


Mansor A.F.,Kulliyyah of Engineering | Ibrahim I.,Kulliyyah of Engineering | Voiculescu I.,The New School | Nordin A.N.,Kulliyyah of Engineering
IFMBE Proceedings | Year: 2016

Electrical Cell-Substrate Impedance Sensing is a powerful tool for monitoring real time cells properties such as adhesion, mobility and cytotoxicity. In this study, a silver/silver chloride screen-printed impedance biosensor was developed to characterize A549 lung carcinoma cells growth in the presence of collagen I, Bovine. Collagen acts as an extracellular matrix (ECM) for A549 and promotes cell attachment. The sensor was incorporated with a culture well which was fabricated from polydimethylsiloxane (PDMS). A549 cells were cultured in the chambers and impedance measurements were taken at 12 hours intervals for 120 hours. Cell Index (CI) were calculated from the impedance data and plotted in comparison with growth profile of the cells in T-flasks for validation of the sensor’s functionality. A549 cells were also treated with antitumor drug; Paclitaxel and its response were monitored over 5 days. Experimental results show significant change in CI during growth and death after exposure to Taxol, indicating that tumor growth was inhibited in the presence of Taxol. © International Federation for Medical and Biological Engineering 2016. Source

Discover hidden collaborations