Judul: Study Production Process of Biodiesel from Alexandrian Laurel Seed Oil (Calophyllum inophyllum L.).
Abstrak: National fossil fuel consumption is increasing. In 2004, solar consumption rise to 26,9 billion liters, at 2010 is predicted to rise to 34,71 billion liters. The consumption of fossil inbalance with its production, this performance need to overcome by looking for an alternative energy resources. Palm oil, jatropha and calophyllum were some of agriculture abundant available in Indonesia. The jatropha used was constrained by a low oil production, average oil production is 1.892 liters/ha/year. Whereas palm oil is 5.950 liters/ha/year, however it compete with food needs and other oleochemical product. The use of calophyllum give an advantage as its production of 100 kg (220 lb) nuts/tree/year or 4.585 kg oil/ha/year. Although the oil has a high acid value and takes longer time that is 7 or 8 years before fruit production. The research was done by combining the process that is esterification, transesterification and netralization to produce oil to meet the SNI standard (number 04-7182-2006). The purpose of this research was to determine the molar ratio of methanol in esterification, and esterification time to obtain oil with low acid value. The esterification conditions than combine with transesterification and netralization in order to produce biodiesel that meet the standard requirement. The best oil produced from esterification was obtained by applying molar ratio methanol of 20:1 in 60 minute, the acid value of oil was 2,97 mg KOH/g feed. The best process combination to produce biodiesel obtained by esterificationnetralization- transesterification (E1NT) applying molar ratio methanol of 20:1 in 60 minute. Its gave acid value 0,71 mg KOH/g feed, kinematic viskosity 2,59 cSt, density 0,89 g/ml, water content 0,05% and yield 47,76%.
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Judul: Process design of biodiesel production from alexandrian laurel seed oil (Calhyllum inophyllum L.)
Abstrak: Biodiesel that can be used directly or mixed with diesel oil is a promising alternative diesel fuel obtained from vegetable oils, animal fats, or waste oils by transesterifying the oil or fat with an alcohol such as methanol. The aim of this research was to design a process of biodiesel production by esterification and transesterification of Alexandrian laurel seed oil. Results show that the best esterification process is obtained at the temperature of 58.1° C, stirring speed of 300 rpm, HCl catalyst of 5.9% from FFA content, and the methanol-FFA molar ratio of 22.2:1.
Keyword: Surface Respon Methode, Esterification, Transesterification, Reaksi kinetik

Judul: Closed Knight’s Tour pada Papan Catur Berbentuk Persegi Panjang dengan Ukuran Maksimal 8 × 8
Abstrak: Closed Knight’s Tour merupakan langkah kuda yang mengunjungi setiap kotak pada papan catur tepat satu kali dengan langkah kuda berawal dan berakhir pada kotak yang sama. Graf yang terbentuk dari closed knight’s tour dinotasikan sebagai graf G(m,n), dengan m adalah banyaknya baris dan n adalah banyaknya kolom. Graf tersebut memuat Hamiltonian cycle. Sebuah graf terhubung G adalah graf bipartite jika dan hanya jika graf tersebut tidak memiliki cycle dengan panjang ganjil. Papan catur yang memenuhi syarat cukup untuk memiliki closed knight’s tour adalah papan catur berukuran 5 × 6, 5 × 8, 6 × 6, 6 × 7, 6 × 8, 7 × 8, dan 8 × 8.
Keyword: bipartite, closed knight’s tour, hamiltonian cycle, knight’s tour, teori graf