Judul: Pembuatan Biopelet Dari Bungkil Jarak Pagar (Jathropa Curcas L.) Dengan Penambahan Sludge Dan Perekat Tapioka
Abstrak: Seed of jatropha (Jatropha curcas L) contains 60 % kernel (weight) and 40 % husk (weight). Its nucleus’s seeds contain 40 – 45 % oils that can be separated into jatropha oil either with mechanical or extraction way (Hambali et al. 2006). More than its 60 % component is an oil cake. The huge amount of oil cake can be used as a solid fuel such as Biomass Pellets (Biopelet). Biopelet has diameters 3 – 12 mm and 6 – 25 mm long. Biopelet is produced by continuous inlet dry materials that is pushed and pressed through steel ring that has particular holes. The pressing process produces solid materials that will be broken into specific size (Ramsay (ed) 1982). Jatropha oil cakes have a weakness as a solid fuel. It has no high heating value and its physic characteristic that has low binder. The addition of sludge in this research are expected to increase the heating value. Sludge can be used as an alternative heating resource. Binding problems can be solved by adding tapioca. Tapioca is used because the price is cheap. But it has a weakness, tapioca will decrease heating value on the product. Binding agents also produce smoke. Optimum adding of tapioca is not more than 5% (Sudrajat and Soleh, 1994). The most important parameter of Biomass fuel is heating value (Grover et al, (eds) 2002). Heating values implies energy that is binded on the fuel with standard from environment. The standard are temperature, water (liquid or vapor), CO2, O2, etc (Palz, 1985). This research starts with physic and burning characterizations of jatropha oil cakes. Biopelet produce in the pellets mill that has capacity 350 kg/ hour. Production held in PT Indofeed Bogor. Biopelet parameters test conducted at Laboratories of Biomass Energy and Chemistry, Forest Product Research and Development Center. The final step of this research is found the comparison of quality between biopelet jatropha oil cake with adding sludge and tapioca and biopelet jatropha oil cake without adding sludge and tapioca. Experimental design used in this research is using Random Complete Design with two factors (RAL factorial). The first is the addition of sludge treatment with three levels, which is, 2%, 4% and 6%, while the second factor is the addition of tapioca adhesive that also has three levels of treatment, which is 1%, 3% and 5%. From the results of the research obtained, although the results of interaction from two factors of treatment, the sludge and tapioca adhesive does not produce real difference, but with the combination can further improve value of the some expected parameters. Combination of sludge 6% and 3% tapioca, can increase heating value to 4914 Kcal / kg, meaning that the combination treatment can increase the heating value 5.62% of the value content from biopelet (control ). So also for bound carbon, a combination of sludge 6% and 1% tapioca can increase the level of bound carbon of 24.41% of the value content of carbon bound control, the combination treatment has value of carbon content of 20.59%. v The addition of sludge and tapioca
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Judul: Biopelet Mixed of Bintaro Fruit Biomass (Cerbera manghas) and Coconut Shell (Cocos nucifera L)
Abstrak: Limbah biomassa buah bintaro dapat diolah menjadi bioenergi berupa biopelet. Penelitian ini bertujuan untuk mengetahui karakteristik biopelet campuran biomassa buah bintaro dan tempurung kelapa dengan penambahan tapioka terhadap sifat fisis dan mekanis serta menentukan formulasi komposisi biopelet terbaik. Tahapan penelitian ini meliputi persiapan bahan baku, karakterisasi bahan baku pencampuran dan pencetakan biopelet, serta pengujian karakteristik biopelet. Komposi campuran biopelet terdiri dari A (bintaro dan tempurung kelapa); B (arang bintaro dan tempurung kelapa), C (arang bintaro dan arang tempurung kelapa); D (kontrol untuk masing-masing bahan). Perbandingan bahan dari setiap perlakuan A, B, dan C adalah 80:20, 60:40, 40:60, dan 20:80. Pengujian biopelet didasarkan pada parameter kadar air, kadar abu, kadar zat terbang, kadar karbon terikat, kerapatan, dan nilai kalor sesuai dengan SNI 8021-2014. Hasil perhitungan menggunakan metode perankingan diperoleh perlakuan terbaik adalah formulasi C3 dengan komposisi 40% bintaro dan 60% arang tempurung kelapa (skor 9,07). Bintaro dapat menjadi substitusi 40% dari arang tempurung kelapa, dan telah memenuhi kualitas biopelet terbaik dengan karakteristik yang dimiliki oleh formula biopelet C3 yaitu kadar air 0,49%, kadar abu 3,09%, kadar zat terbang 40,73%, nilai karbon terikat 55,69%, kerapatan 0,76 g/cm3, keteguhan tekan 4,40 kgf/cm2, dan nilai kalor sebesar 6080,5 kal/g., Bintaro fruit biomass waste can be processed into bioenergy in the form of biopelets. This study aims to determine the characteristics of the biopelet mixture of bintaro fruid and coconut shell using tapioca adhesive to physical and mechanical parameter also to determine the best formulation of biopelet composition. The stages of this research include the preparation of raw materials, characterization of raw materials, mixing and forming of biopelets, and testing of biopelet characteristics. Biopelet mixture consists of A (bintaro and coconut shell); B (bintaro charcoal and coconut shell), C (bintaro and coconut shell charcoal); D (control for each ingredient). The ratio of raw materials for each treatment A, B, and C are 80:20, 60:40, 40:60, and 20:80. Biopelet testing is based on parameters of moisture content, ash, volatile substance, fixed carbon, density and calorific value according to SNI 8021-2014. By the ranking method, the best treatment was formulation C3 with a composition of 40% bintaro and 60% coconut shell (score 9.07). Bintaro can be a substitute for 40% of coconut shell charcoal, and has met the best biopelet quality with characteristics of C3 biopelet formula are moisture content 0.49%, ash of 3.09%, volatile substances 40.73%, fixed carbon 55.69%, density 0.76 g/cm3, compressive strength 4.40 kgf/cm2, and a calorific value of 6080.5 cal/g.
Keyword: bintaro, biomass, biopelet, calorific value, coconut shell

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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