Judul: Performance test on bio oil stove using calophyllum oil and cerbera oil as the fuel
Abstrak: Bio oil stove is a wick stove which was modified from kerosene stove, and designed for vegetable oil as its fuel. The objective of the research was to conduct performance test of the stove by using Cerbera oil and Callophylum oil as fuel. The result shows that the heat capacity of the stove by using Callophylum oil as fuel was 172.58 kJ/minute, and by using Cerbera oil was 199.95 kJ/minute. The total fuel consumption were 0.12 kg for Callophylum oil usages and 0.17 kg for Cerbera oil usages. Stove efficiency and system efficiency with Callophylum oil usages were 33.64% and 13.96%. While, Callophylum oil usages only 19.39% and 9.28%., Kompor minyak nabati merupakan jenis kompor bersumbu banyak (multi-wick) yang menggunakan bahan bakar minyak nabati sebagai bahan bakarnya, kompor ini merupakan modifikasi dari kompor minyak tanah. Penelitian ini bertujuan untuk menguji kinerja kompor minyak nabati dengan menggunakan minyak bintaro dan minyak nyamplung. Hasil pengujian menunjukkan kapasitas panas yang dihasilkan oleh kompor minyak nabati dengan bahan bakar minyak nyamplung adalah 172.58 kJ/menit dan dengan bahan bakar minyak bintaro 199.95 kJ/menit. Konsumsi bahan bakar total kompor minyak nabati dengan bahan bakar minyak nyamplung dan minyak bintaro adalah masing-masing 0.12 kg dan 0.17 kg. Efisiensi kompor dan efisiensi sistem kompor minyak nabati dengan bahan bakar minyak nyamplung adalah 33.64% dan 13.96%. Sedangkan efisiensi kompor dan efisiensi sistem dengan bahan bakar minyak bintaro adalah 19.39% dan 9.28%.
Keyword: vegetable oil, stove, efficiency, Cerbera, Callophylum

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: Metrik Einstein (Anti-) Self-Dual Berdimensi Empat dengan Metode Cartan
Abstrak: Gravitational field equation can be formulated in differential forms (differential geometry), which describes gravity as a manifestation of the curvature of space-time. Curvature of space-time is characterized by a metric that satisfies the gravitational field equation. With differential forms it can be formulated the (anti-) self-dual Einstein equation, which is a modification of the Cartan structure in (anti-) self-dual basis. Calculation of (anti-) self-dual metric with (anti-) self-dual Einstein equation is simpler than the calculation using Christoffel symbols.
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