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: Pembuatan Biopelet dari Cangkang Kelapa Sawit dengan Penambahan Arang Cangkang Sawit dan Serabut Sawit sebagai Bahan Bakar Alternatif Terbarukan
Abstrak: Biopellet is one of an alternative energy for rural community. The abundance of palm shell and palm fiber is a potential source of biomass that can be converted into biomass pellet (biopellet). Pelletization can improve the quality and burning characteristic of the biomass. The purpose of this Fesearch was to learn the utilization of palm shell and fiber into biopellet production and to know the affectation of addition the palm shell charcoal and palm fiber. The research begun with an analysis of physic-chemical properties contained in the raw material. Then the result continued by analysis of tombustion characteristic. Based on the physic-chemical properties and the combustion Characteristics; biopellet of palm shell that contained 80% of palm shell and 20% of palm shell charcoal has the best quality. It has 0.47% of moisture content; 9.83% of ash content; 55.34% of Polatile matter; 34.84% of fixed carbon content; 5,265.92 kcal/kg of the heating value; 1,260.30 kg/m² f bulk density; and 82.09 kg/cm of strength pressure. The consumption rate of the best formulation biopellet was 1.39 kg/jam and the combustion efficient was 11.59%. The production of palm shell biopellet on a laboratory scale produced yield of 11.54%. Energy input for this process is 101,751.86 cal and energy output is 9,794.61 kcal. Biopellet increased the heating value of palm shell for 25.55% or 7,008.84 kcal/kg.
Keyword: Palm shell, Palm fiber, Biopellet, Charcoal, Carbonization

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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