Papers by Author: Ahmad Faris Ismail

Abstract: In this study, three different concentration of organic loading rate (OLR) were investigated to examine the effect of the change in the organic loading rate on the efficiency of the biogas production. Daily amount of biogas of different type of organic loading rate (OLR), rates of production of biogas, removal efficiencies of chemical oxygen demand (COD), total solid (TS) matter, volatile solids (VS) matter from the slurry were investigated in 30 days retention tyme using 50 L digester. The digester was operated at different organic feeding rates of 25000 mg/L COD, 50000 mg/L COD, and 75000 mg/L COD. The material used in this system is the fruits waste, vegetables waste and cow dung. The system operated in continuous system. The reactor showed stable performance with the highest quality of methane (concentration about70.3% of CH4) and rate of biogas production is 38.1 L/day with COD reduction of 52.1% during organic loading rate 50000 mg/L COD. As the organic loading rate was increased, the COD degradation and biogas yield decreased. Based on this result, the OLR of 50000 mg/L COD is suggested as design criteria for pilot biogas production.

Abstract: Any useful object is commonly made from selected engineering materials with proper shape and dimension. The selection of materials and manufacturing processes is an important criterion towards the production of useable and affordable objects. The technologies behind this knowledge are needed to acquire through study, proper education, practical training and scientific research related to Materials and Manufacturing Engineering (MME). Allah (swt), the sources of all power and knowledge, has bestowed the Guide Book, the Holy Qur’an through His beloved Messenger Prophet Mohammad (pbuh) to the mankind. Allah (swt) narrated various stories in many Surahs of the noble Qur’an related to applied science and technology. This paper is an attempt to view the integration between the revealed knowledge and the science and technology based knowledge related to engineering materials and manufacturing processes. Finally, stresses have been given to acquire knowledge on science and technology based education and understanding, and disseminate it for the cause of humanity.

Abstract: Green sand casting and chill mould casting methods are representing the slow and fast cooling rates of the brass casting, respectively. The compositions of the raw material for this study were about Cu70 and Zn30, which falls under alpha (α) brass. Slow cooling rate casting shows coarse dendritric structures with large spacing between the dendrites. On the other hand, faster cooling rate casting shows finer grains with shorter dendrite spacing. The developed structure during solidification influences the properties of the cast samples. As grain size decreases, the strength of the cast brass increases; micro-porosity in the casting decreases and the tendency for the casting to fracture also decreases. However, the macro-examinations of fracture surfaces of these castings show the differences in the cast samples. Fracture surfaces of the sand cast specimen show larger dimples taking longer time to break indicating higher elongation. However, chill cast specimen shows smaller dimples and cleavage type fracture surface having higher strength and lower elongation.

Abstract: Aluminium-silicon alloys having different silicon contents (13, 20 and 27 percent) were used in the present study. The molten alloys were poured in to a mild steel die to cast tensile test bars. Then tensile and hardness tests were performed in order to analyze the properties and fracture surfaces of the cast specimens. Results show that as silicon content increases, the alloy becomes harder and less ductile. At the same time, the presence of alloying and impurity elements in the alloys forms complex compounds and intermetallic phases. They present deleterious effects on the strength of the alloys, causing a lowering of the energy required to fracture the test specimens with little permanent extension. However, heat treatment operations altered the structures and properties of the aluminium-silicon alloys. Heating to higher temperature, then quenching, ageing and tempering make the alloys stronger up to 13% silicon and beyond that limit the alloys become weaker, fracturing at lower load. The appearance of fracture surfaces after tensile testing showed these differences. This investigation also suggests that for the aluminium-silicon alloys containing 20% and 27% silicon do not require any expensive and time consuming thermal treatment operations, since properties do not improve with such treatments.

Abstract: Carbon are well known as active materials for energy storage and conversion. They are preferred because carbon materials have high electrical conductivity, low cost, high surface area, porosity, formability and possess good chemical and electrochemical resistivity. The most recently discovered novel carbon material is the carbon nanotubes, having unique geometrical structure and stable mechanical and chemical properties. The starting materials for carbon nanotubes production widely used are high purity graphite. Thus, two types of carbons were studied and thermal treatments were conducted at temperatures ranging from 600 – 800 °C for several hours. The effect of the pretreatment upon their morphology and surface area were looked into. It was found that significant changes occurred for the natural carbons while the synthetic carbons showed little or no changes at the particular temperature range. The thermal treatment has resulted in the exposure of fresh edge planes and microparticles as well as changes in the specific surface area and enhances their adsorption properties.