Judul: Study on plant oil capillarity in wick cook stove
Abstrak: Rural households consume about 20% of total national consumption of fossil fuel and over 68% of these are in the form of kerosene for household cooking and lighting. Since several years ago Indonesia became net importer of oil including kerosene which have caused a big burden to government budget. Therefore, to overcome this problem, the government has enacted President Regulation No.5, 2006 on National Energy Policy and the Department of Energy and Mineral Resources Regulation No. 32, 2008 on Energy Self-Supporting Village Program. The objective of this study was to investigate the possibility of using several plant oils an alternative cooking fuel and to determine their respective thermal efficiency. Due to their high viscosity, the velocity of these plant oils in stove wicks is very slow causing inperfect burning condition. There were two methods of improvement to solve the problem, namely, by determining fuel characteristics to meet kerosene cook stove or modifying cooking stove design based on biofuel characteristics. The focus of this study was on the latter method. The first attempt was to reduce the viscosity of plant oil by providing metal bar connecting the flame and oil tank. By determining the capilary height of each plant oil within the wick bundles, it was possible determine the optimum height of the wicks which consequently can shorten the height of the cooking stove. During the test, Coconut oil, jatropha oil, bintaro oil, peanut oil, and used cooking oil had been selected and was used kerosene as control. There were four parameters measured during a series of test runs, namely, the flaming ability, the capillaryy height, fuel consumption, and combustion efficiency. Capillaryy height and oil rising velocity within the wicks of the tested plant oil could be reduced due to heating efect of heat conduction by the installed steel bar. From the experimental studies using modified cook stove with shortened wick length it was found that the thermal efficiency for kerosene, coconut oil, peanut oil, bintaro oil, used palm oil, and jatropha oil were 44.5%, 25.6%, 17.3%, 19.7%, 18.4%, and 24.5% respectively. The overall fuel consumption rate was in the range of 0.56 g/s for kerosene and 0.32–0.37g/s for plant oil and 1.30-2.90 g/s for plant oil-kerosene mixture. The provision of heat conductor had improved the efficiency of the modified stove to 41.2% using pure kerosene, 37.8% with coconut oil-kerosene mixture 19.5%, for peanut oil-kerosene mixture, 34.4%, for bintaro oil-kerosene mixture 22.7%, used plant oil, and 35.7% using physic nut (Jatropha Curcas), respectively. The overall fuel consumption rate was in the range of 2.02 g/s for kerosene, 1.15–1.33 g/s for plant oil and 4.68-10.44 g/s for plant oil-kerosene mixtures. In order to optimize the capillary effect further, a mathematical model was developed. The model relates the capillary height and the rising velocity of plant oil within the stove wicks with the wicks physical properties and transport properties of the tested plant oils.
Keyword: Combustion Efficiency, Wick Stove, Capillary Effect

Judul: Modifikasi dan Unjuk Kerja Kompor Sumbu Tunggal Berbahan Bakar Minyak Bintaro
Abstrak: Bintaro (Cerbera odollam gaertn) has oil content 46-64% and it is potential as a biofuel feedstock. Bintaro oil, like other bio oil, has high viscosity. Due to it, the capillarity of oil on the wick is very low. This will affect to the combustion. The objectives of this study were to analyze the properties of Bintaro oil and to examine the use of Bintaro oil as fuel for a single wick stove. In this study, sample of Bintaro oil was processed from Bintaro fruits collected around Bogor. Sample of single wick stove which was familiar stove used by household in Bogor area, was modified mainly at part of flame holder at the height of 5, 6, 7, 8 and 11 cm. The caracteristic of combustion was investigated from the flames temperature and contour at different height of flame holder. The result showed that heat loss rate values for Bintaro oil were 76.6 W, 88.5 W, 100.7 W, 111.1 W and 142.8 W for the height flame holder of 5, 6, 7, 8 and 11 cm. The flame temperature based on the heat loses were 443.97, 476.75, 451.95, 450.5 and 454.77°C, respectively. For kerosene, the heat loss and flame temperature were 245.6 W and 730.77 °C for the height flame holder of 11 cm. The boiling test resulted that for kerosene with flame holder of 11 cm ,the water boiled at temperature of 100°C for 26 minutes. The average temperature was 637 °C and the power was 1.318 W. For Bintaro oil with the height of flame holder of 6 cm, resulted the flame temperature of 482°C, the heat loss of 1.092 W, and the water boiled of 45 minutes.
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Judul: Grup dan Homomorfisma Grup pada Rubik Revenge
Abstrak: Rubik cube is a kind of puzzle game. A player must arrange rubik sides, which have been disordered, back to the position where every side has the same colour. This paper does not focus on the settlement solution, but instead on proving the existence of a group homomorphism between rubik movement group and S96 symmetric permutation group in rubik revenge. Firstly, it has been proved that rubik movement set is a group. Then, it also has been proved that the M set, which contains numeric labels of 1 until 96 in cubinos sides, is S96 symmetric permutation group.
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