Judul: Biogas Production from a Mix of Cow Mature with Odot Grass (Pennisetum purpureum cv. Mott)
Abstrak: Biogas merupakan salah satu sumber energi alternatif yang dapat diperbarui karena menggunakan bahan baku yang berasal dari kotoran ternak. Penelitian bertujuan untuk menganalisis produksi biogas dari campuran rumput odot dan kotoran sapi. Penelitian dilakukan dengan 3 perlakuan yaitu 100 % kotoran sapi (kontrol), 70% kotoran sapi +30% rumput odot, dan 50% kotoran sapi +50% rumput odot. Hasil penelitian menunjukkan bahwa campuran biogas kotoran sapi dengan rumput odot sangat nyata (P<0,05) terhadap produksi biogas yang dihasilkan nilai produksi berturut-turut untuk K₁₀₀R₀, K₇₀R₃₀, dan K₃₀E₃₀ sebesar 191,3500; 99.0067 dan 0,0000. Rasio C/N bahan tiap perlakuan sebesar 27,52; 25,32 dan 23,85. Temperature harian rata-rata hampir sama untuk semua perlakuan yaitu 27-29°C. Nilai pH tiap perlakuan sebesar 5,90-7,27; 5,00-7,00 dan 4,77-6,70. Kandungan TS, VS awal dan akhir tiap perlakuan adalah TS awal 11,014; 11,007; dan 11,195; TS akhir 6,960; 6,794; dan 6,714; VS awal 8,838; 8,965; dan 9,309; VS akhir 5,734; 5,728; dan 5.831. Nyala api biogas dengan campuran rumput odot (K₁₀₀R₀) dan (K₇₀R₃₀) menghasilkan biogas berwarna biru sedangkan (K₅₀R₅₀) tidak menghasilkan nyala api., Biogas is one of the alternative energy sources that can be updated because it uses raw materials derived from livestock manure. The research aims to analyze biogas production from a mixture of odot grass and cow manure. The study was conducted with 3 treatments namely 100% cow manure (control), 70% cow manure + 30% odot grass, and 50% cow manure + 50% odot grass. The results showed that the mixture of cow manure biogas with odot grass was very real (P<0.05) against the production of biogas produced successive production values for K₁₀₀R₀, K₇₀R₃₀, and K₃₀E₃₀ 191.3500; 99,0067 and0.0000. TheC/N ratio of each treatmentis 27.52; 25.32 and 23.85. The average daily temperature is about the same for all treatments which is 27-29°C. The pH value of each treatment is 5.90-7.27; 5.00-7.00 and 4.77-6.70. The content of TS, VS the initial and final of each treatment is the initial TS of 11,014; 11,007; and 11,195;final TS6,960; 6,794; and 6,714;initial VS8,838;8,965; and 9,309; final VS of 5734; 5,728; and 5,831. Biogas flames with a mixture of odot grass (K₁₀₀R₀) dan (K₇₀R₃₀) produce blue biogas flames (K₅₀R₅₀) do not produce flames
Keyword: Biogas, Cow Manure, Fermentation, Odot Grass, Production

Judul: Biogas Production from a Mix of Cow Manure with corn straw (Zea mays. L)
Abstrak: Biogas merupakan salah satu sumber energi alternatif yang dapat diperbarui karena menggunakan bahan baku yang berasal dari kotoran ternak. Tujuan penelitian ini adalah menganalisis roduksi dan kualitas biogas dari campuran kotoran sapi dengan jerami jagung (Zea mays. L). Penelitian dilakukan dengan 3 perlakuan yaitu kontrol sebanyak 100% kotoran sapi + 0% jerami jagung (S100J0), 75% kotoran sapi + 25% jerami jagung (S75J25), serta 50% kotoran sapi + 50% jerami jagung(S50J50) dan masing-masing 3 kali ulangan dengan analisis data menggunakan rancangan acak lengkap (RAL). Hasil penelitian menunjukkan bahwa campuran biogas kotoran sapi dengan jerami jagung berpengaruh nyata (P>0,05) terhadap produksi biogas yang dihasilkan (S100J0) menghasilkan produksi biogas yang paling tinggi. Suhu harian rata-rata hampir sama untuk semua perlakuan yaitu 27- 29 °C. Kandungan TS, VS awal dan akhir berturut-turut untuk S100J0, S75J25, dan S50J50 14,940; 12,916; dan 13,873. VS awal 12,660; 10,903; dan 10,996. TS akhir 10,643; 7,900; dan 10,550. VS akhir 6,286; 4,546; dan 7,323. Perlakuan S100J0 menghasilkan produksi yang lebih tinggi dan perlakuan penambahan jerami jagung 50% menghasilkan kualitas api yang baik berwarna biru, Biogas is a renewable alternative energy source because it uses raw materials derived from livestock manure. The purpose of this study was to analyze the production and quality of biogas from a mixture of cow dung and corm straw (Zea mays L). The study was conducted with 3 treatments, namely control as much as 0% corn straw or 100% cow dung (S100J0), 75% cow dung + 25% corn straw (S75J30), and 50% cow dung + 50% corn straw (S50J50) and 3 replications each with data analysis using a completely randomized design (CRD). The results showed that the mixture of cow dung biogas and corn straw had a significant effect (P>0,05) on the production of biogas (S100J0) produces the highest biogas production. The average daily temperature was almost the same for all treatments, namely 27-29 0C. The initial and final TS, VS content for S100J0, S75J25, and S50J50 14,940; 12,916; and 13,873. respectively. Initial VS 12,660; 10,903; and 10,996. Final TS 10,643; 7,900; and 10,550, and final VS 6,286; 4,546; and 7,323. The S100J0 treatment resulted in higher production and the addition of 50 % water hyacinth resulted in a good quality blue flame.
Keyword: alternative energy, biogas, corn straw, cow manure

Judul: Hamiltonian formulation for linear waves motion in two layers fluid
Abstrak: The surface wave could be considered as a wave that separates two fluids, namely water and air. Based on this assumption, it is introduced the interfacial wave, a wave between two layers of fluid with different density. The formulation of interfacial waves motion begins with deriving the base equation of irrotational ideal fluid. Furthermore, according to irrotational fluid assumption, the base equation can be stated in velocity potential. In this derivation, the fluids domain is assumed to be restricted by rigid lid boundary conditions, both at the upper and lower limit. Therefore, the interfacial waves motion can be explained in a hamiltonian formulation. In the hamiltonian formulation, total energy is defined as the sum of kinetic and potential energy. The hamiltonian system is obtained from reduction of kinetic energy by using the Dirichlet Neumann Operator. The resulted kinetic energy equation is nonlinear. Therefore, this form is linearized by first part of the Taylor expansion. This linearization gives a dispersion relation of linear wave. Based on this dispersion relation, the phase speed of the linear wave depends on the density ratio of the two layers fluid.
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