Judul: Pengolahan Fine Coal dan Aplikasinya sebagai Briket
Abstrak: Fine coal is a by-product of coal washing, which is not utilized and nearly 2 billion tons per year of fine coal is waste. The objectives of the research are to treatment fine coal using centrifugation and coagulation-flocculation and use it to produce briquette. The fine coal was treated using centrifugation in laboratory scale. Coagulation-flocculation steps used alum as coagulant with starch (nonionic polymer) and sulfate starch (anionic polymer) as flocculants. Coagulationflocculation using alum-starch was more effective than that of using centrifugation and alum-starch sulfate based on the highest turbidity reduction efectiveness of 99.96%. The results of this test showed that particles of fine coal thought to be negatively charged. The fine coal was then applied to produce briquette using tapioca flour as binding material at concentration of 3%, 5%, and 10%. Characterization of the fine coal briquette showed that the volatile matter and ash content did not meet the coal briquette standard, as stipulated in Permen ESDM No 47/2006
Keyword: Bogor Agricultural University (IPB), starch, flocculation, fine coal, coagulation, briquette

Judul: Pemanfaatan limbah Tebu menjadi briket dan biopelet
Abstrak: Sugarcane (Saccharum officinarum) is one of Indonesia's main commodities that provide benefits for life. Sugarcane bagasse and leaves are major waste of sugar mills. Both of waste have not been optimally used. This research conduct a briquette procesing used bagasse and biopellet processing used sugarcane leaves. The aims of this study was to determine concentration of adhesive of briquette and to optimize biopellet process at compression temperature and time. Briquette was made by the addition of tapioca adhesive with concentration of 5, 10 and 15%. Biopellet made used compression temperature and compression time with compression temperature were varied iii from 130 - 270oC and compression time consisted of 8 - 22 minutes. The best briquettes treatment obtained at a concentration of 5% adhesive, with value of 3.87% moisture content, 3.35% ash content, 76.35% volatile matter, 20.29 fixed carbon and heat level 4155 kcal/kg. Sugarcane leaves biopellet has optimal at compression temperature of 250oC for 20 minutes. Compression with these conditions produced moisture content of 3.41%, ash content of 12.19%, compressive strength of 119.22 kgf/cm2 and heat level of 4490 kcal/kg.
Keyword: Bogor Agricultural University (IPB), bagasse, sugarcane waste, bioenergy, briquette, biopellet

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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