No abstract

Vegetable oils have been investigated to replace petroleum lubricants due to their environmental-friendly characteristics and have become a vital source of bio-lubricants. In the investigation of the tribological characteristics of palm oil as the vegetable oil, using in its neat form or as partial bio-lubricants, a reciprocating machine was employed. Initially, refined, bleached and deodorised (RBD) palm olein with mineral oil blends were optimised using the design of experiments procedure from the outcomes of the four ball tribotester. The optimised blend was found to have characteristics that were better or at par with mineral oil. Then, a reciprocating machine was used for verifying the blend. In the investigation of the optimised blend, the sample was tested for a total of 60 hr in intermittent operation. Other than having similar viscosity for the ISO requirements, the optimised blend demonstrates decreased in the values of material weight loss and cylinder temperatures as compared with mineral oil. Finally, it is concluded that the RBD palm olein blend (E53.11/RB46.89) could be a potential partial bio-lubricant due to having no negative impact on wear and decent performance as a bio-lubricator.

The study was carried out to determine the density and mechanical properties of Al-7%Si alloy-Bagasse Ash (BA) composite produced at 800 o C. BA obtained at 700 o C and having high silica and alumina contents of up to 77.29% and 10.95%, respectively was used as reinforcement and varied from 0vol% to 30vol%. The density and some mechanical properties of the produced composites were determined. The results showed that the density decreases with percentage increase in reinforcement from 2840.242kgm-3 to 2292.208kgm-3 with the minimum value at 30vol% BA. The results of the mechanical properties tests showed that, the ultimate tensile strength (UTS) varies from 139.677MNm-2 to 176.683MNm-2 with maximum value at 10vol% BA, Young modulus varies from 1429.890MNm-2 to 1725.425MNm-2 with maximum value at 10vol% BA, impact strength varies from 75.401kJm-2 to 128.262kJm-2 with maximum value at 10vol% BA and hardness varies from 70.467RHV to 90.767HRV with maximum value at 20vol% BA and with all the hardness values better than that of the control sample. The results also showed that, the fatigue strength varies from 0.066x10 6 cycles to 1.797x10 6 cycles with maximum value at 15vol% BA and the percentage elongation having approximately the same value.The results of the statistical analysis showed that there are significant differences among the means of each property of the composites at various levels of BA replacement (P<0.05).It was concluded that bagasse ash can be used as reinforcement in aluminium composites and the produced composites could be used in automobile industry for the production of engine blocks, pistons, among others.

Color images reveal more meaningful information to the human observers rather than grayscale ones. Regardless of the advantages of the existing well-known objective image quality measures, one of the common and major limitations of these measures is that they evaluate the quality of grayscale images only and don't make use of color information. In this paper we propose an improved method for image quality assessment that adds a color comparison to the criteria of the well-known Multiscale Structural Similarity index (MSSIM). We evaluated the new color image quality measure through human subjective experiments. Our human subjective evaluation data contains 25 reference images and 875 test images produced by five popular color quantization algorithms. Each of the quantized images was evaluated by twenty two subjects and more than 19200 individual human quality judgments were carried out to obtain the final mean opinion scores. We also tested the proposed method on TID2008 image database to further verify our results. These results indicate that adding color comparison improves MSSIM for many distortions in TID2008 and for assessing quantized images in our database.

Accumulative roll bonding was successfully used as a severe plastic deformation method to produce Al–SiC composite sheets. The effect of the addition of SiC particles on the microstructural evolution and mechanical properties of the composites during accumulative roll bonding was studied. The Al–1, 2 and 4 vol.% SiC composite sheets were produced by accumulative roll bonding at room temperature. Monolithic Al sheets were also produced by the accumulative roll bonding process to compare with the composite samples. Field emission scanning electron microscopy revealed that the particles had a random and uniform distribution in the matrix by the last accumulative roll bonding cycles, and strong mechanical bonding takes place at the interface of the particle matrix. This microstructural evolution led to improvement in the hardness, strength and elongation during the accumulative roll bonding process. It is also shown that by increasing the volume fraction of particles up to 4 vol.% SiC, the yield and tensile strengths of the composite sheets increased more than 1.2 and 1.3 times the accumulative roll-bonded aluminum sheets, respectively. Field emission scanning electron microscopy observation of fractured surface showed that the failure broken of composite was shear ductile rupture.