Judul: Pemanfaatan Limbah Kelapa Sawit (Elaeis guineensis Jacq.) dan Serbuk Kayu Mahoni sebagai Bahan Baku Biopelet
Abstrak: Despite widely known for its use as food, palm’s wastes produced by the plantation aren’t optimally used yet. Palm waste has potential to be made into fuel, one of which is biopellet. This research aims to find out the biopellet’s characteristic made from palm waste and examine the effect of augmenting mahoni sawdust toward biopellet’s quality. Materials used are exterior part of palm plant’s trunks, interior part of palm’s trunks, palm’s midrib, leaves, and mixed materials such as mahoni sawdust (0%, 15%, 30%, 50%). Biopellet was made using 40-60 mesh particle and compressed in 200 oC temperature for 15 minutes. Biopellet characteristics were examined using SNI 06-4369-1996 and SNI 01-2891-1992 standard. Research results show that biopellet’s water content is 0.14% - 2.34%, with volatile matter 62.34% - 76.29%, 1.12% - 13.32% ash content, 0.65 g/cm3 – 0.94 g/cm3 density, calor value as much as 4269.27 cal/g – 4729.99 cal/g, sulphur content 0.012% - 0.038%, nitrogen 0.290% - 1.95%, and chlorine content < 0.01%.
Keyword: calor value, biopellet, sawdust, oil palm

Judul: Karakteristik Pelet Campuran Tandan Kosong Kelapa Sawit :(Elaeis guineensis jacq.) dan Arang
Abstrak: Oil palm empty fruit bunches (EFB) is very abundant in Indonesia. It has huge potential to be used as renewable energy. This study tries to assess the use of EFB as biopellet to be used as alternative renewable fuel. Pellets are made from mixing oil palm empty fruit bunch powder and oil palm empty fruit bunch char at a ratio of 0, 10, and 20% respectively. Biopellet is molded using pellet mill machine that produces cylindrical shaped pellets with a diameter of 0.4 cm and a length of + 4 cm. The result of the study indicates that adding char could increase the calorific value of pellets. The calorific value of pellets to which 10 and 20% of char has been added will produce pellets that have a calorific value of 17,21 MJ/kg and 17,38 MJ/kg respectively. Meanwhile the calorific value of dry empty palm oil bunch feedstock and its pellets are 16,21 MJ/kg and 17,38 MJ/kg respectively. In addition to calorific value, adding char to pellets made from oil palm empty fruit bunched will reduce the moisture and ash contents and improve the bulk density of pellets. In general, the quality of biopellets that have been mixed with 20% of char is capable of meeting the French standard as regard to diameter size, length size, moisture content, and calorific value parameters, on the other hand as regard to ash content, and bulk density, all biopellet types still hasn’t been able to fulfill the requirements.
Keyword: alternative renewable energy, charcoal, calorific value, biopellet, oil palm empty fruit bunch

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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