Judul: Biopelet: Energi Terbarukan dari Batang Kelapa Sawit
Abstrak: Oil palm trunk (OPT) is a potentional source of biomass for the production of biopellet. In the present research, biopellets were prepared from 25 years old OPT. It was prepared by mixing the meristem part with various percentages of its bark (0, 10, dan 30% bark content). The properties of the resulting biopellet were statistical examined. The durability of biopellet was measured according to ASABE standard procedures and its combustion behavior was examined by thermogravimetry and differential thermal analysis (TG–DTA). The highest biopellet durability was found for biopellet produced at 130 oC pressing temperature with 30% bark content. Scanning electron microscopy (SEM) of pellet of OPT showed the weak of particle bonding due to low of pelletizing pressure. The moisture content, unit density, ash content, and caloric value of pellets were 3.55–5.35%, 525.56–855.23 kg/m3, 2.76–3.44%, dan 17.89–19.14 MJ/kg, respectively. The combustion profiles of biopellet seemed to be unaffected by the bark content on TGA curve. Thermogravimetric analysis on DTA curve indicated that hemicellulose, cellulose, and lignin retained a different pyrolysis characteristic
Keyword: Bogor Agricultural University (IPB), pyrolysis, durability, pellet, Oil palm trunk

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: 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.
Keyword: