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Ahmad M.Z.,RMIT University | Ahmad M.Z.,Mechanization and Automation Research Center | Golovko V.B.,MacDiarmid Institute for Advanced Materials and Nanotechnology | Adnan R.H.,MacDiarmid Institute for Advanced Materials and Nanotechnology | And 7 more authors.
International Journal of Hydrogen Energy | Year: 2013

Controlled amounts of chemically synthesised gold (Au) nanoclusters were deposited onto tungsten trioxide (WO3) nanostructured thin films as sensors for hydrogen. The Au/WO3 thin films were characterised by XPS, XRD, SEM and TEM. Performance of Au/WO3 films was tested at operating temperatures varying from room temperature to 450 C. It was demonstrated that Au metal loading plays an important role in defining enhancement of the sensor response towards hydrogen. "Less is more" principle applies to the reported here sensors as materials made using lower concentration of Au nanoclusters demonstrated significantly better response. HRTEM images of the Au/WO3 thin films provide evidence that the more active sensors are enriched with smaller Au nanoparticles (≤5 nm). Fast response towards H2 within a wide range of industrially relevant concentrations, excellent baseline stability and signal reproducibility at optimized operating temperature demonstrate feasibility of this novel approach toward fabrication of sensors. © 2013, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved. Source


Kakahy A.N.N.,University Putra Malaysia | Ahmad D.,University Putra Malaysia | Akhir M.D.,Mechanization and Automation Research Center | Sulaiman S.,University Putra Malaysia | Ishak A.,University Putra Malaysia
Advanced Materials Research | Year: 2013

A study was conducted to test the effects of three different speeds of 1830, 2066 and 2440 rpm of a mower knife with serrated edges and two different feeding angles of 45° and 90° on the pulverization of sweet potato vines. The results indicated that all the treatments were significant at 99% significance level for the pulverized percentage of sweet potato vines remaining on the sieve. The best result was for the 45° feeding angle with lowest vine pulverized percentage of 47.20%. The second speed of 2066 rpm had the finest vine pulverized percentage of 57.47%. The best performance for overlapping effect between feeding angle and speed of mower was achieved by the 45° feeding angle and a mower speed of 1830 rpm resulting in an average percentage of 44.45% of pulverized vines. © (2013) Trans Tech Publications, Switzerland. Source


Ahmad M.Z.,RMIT University | Ahmad M.Z.,Mechanization and Automation Research Center | Wisitsoraat A.,National Electronics and Computer Technology Center | Zoolfakar A.S.,RMIT University | And 5 more authors.
Sensors and Actuators, B: Chemical | Year: 2013

The gas-sensing performances of tungsten trioxide nanorod thin-films toward reducing and oxidizing analytes are reported. The nanostructured thin-films were RF sputtered, via a glancing angle deposition (GLAD) technique, with different thickness onto conductometric transducers. Thin-film micro-characterization of the surface morphology, chemical compositions and crystal structure by SEM, TEM, XRD and XPS showed that the thin layers contained highly porous, nanocrystalline, stoichiometric WO3 nanorod features with average height varying from 140 to 420 nm and diameter ranging from 40 to 60 nm. Initial vapor sensing test results showed that the ethanol response of WO3 nanorod thin-film tended to increase with decreasing film thickness. The optimized sensor operating temperature for ethanol detection was 300 C with a maximum response of 10 to C2H5OH of 200 ppm for the thinnest film. In contrast, the NO2 response was improved by increasing the WO3 nanorod film thickness, and the thickest films exhibited a very large response of 1075 (10 ppm of NO2) at a relatively low optimized operating temperature of 150 C. Moreover, the developed WO3 based sensors showed good repeatability characteristics when exposed to C2H5OH, but exhibited some poisoning effects when tested in an NO2 environment. The interesting surface structure with very high surface-to-volume ratio of the thin films was reasoned to be responsible for the high and fast response when exposed toward both analytes. © 2013 Elsevier B.V. Source


Kakahy A.N.N.,University Putra Malaysia | Ahmad D.,University Putra Malaysia | Akhir MD.,Mechanization and Automation Research Center | Sulaiman S.,University Putra Malaysia | Ishak A.,University Putra Malaysia
Applied Mechanics and Materials | Year: 2013

The effects of a rotary slasher with two different shapes of knives (L and Y-shaped) at three cutting speeds (1830, 2066 and 2044 rpm) were studied on percentage of pulverization of sweet potato vine passing through the sieve (< 28 mm2). The results showed that all the treatments were significant at p 〈 0.05 and p 〉 0.01 significance level. The best result was by Y-shaped knife with highest vine pulverized percentage of 82.76% and a mower speed of 2440 rpm had the finest vine pulverized percentage of 90.48%. The best performance for interaction effects between knife shapes and speeds of mower was achieved by the Y-shaped knife and a mower speed of 2440 rpm resulting in an average percentage of 92.62% of pulverized vine. © (2013) Trans Tech Publications, Switzerland. Source


Kakahy A.N.N.,University Putra Malaysia | Ahmad D.,University Putra Malaysia | Akhir M.D.,Mechanization and Automation Research Center | Sulaiman S.,University Putra Malaysia | Ishak A.,University Putra Malaysia
Key Engineering Materials | Year: 2014

Two different shapes of knives (L and Y-shaped) for the rotary slasher with 30° knife cutting angle at three cutting speeds (1830, 2066 and 2044 rpm) were used to indicate their effects on the power consumption for pulverizing sweet potato vine which passed through the sieve (< 28 mm2). The results indicated that all the treatments were significant at p < 0.01 significance level for the power consumption on sweet potato vine pulverizing. The best result was recorded from L-shaped knife with a power consumption of 52.12 Watts for sweet potato vine pulverization. Meanwhile, the best result was for the mower speed at 1830 rpm with the lowest power consumption of 61.23 Watts. The best performance for interaction between knife shapes and the cutting speeds was achieved by the L-shaped knife at 1830 rpm with lowest power consumption of 50.23 Watts at p < 0.01. Copyright © 2014 Trans Tech Publications Ltd, Switzerland. Source

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