Judul: Pengaruh Taraf Kombinasi Rumput Gajah dan Limbah Tauge sebagai Alternatif Sumber Serat terhadap Kualitas Fisik Pellet Kelinci Selama Penyimpanan.
Abstrak: Sprouts waste (SW) is an alternative materials which potentially replace elephant grass (EG) as a source of fiber on feed. This study aims to test the physical quality of pellets for rabbit which contains SW and EG as a source of fiber with different storage periods. This study was arranged in a Completely Randomized Design Factorial (4x4), contains factor A: sprouts waste levels (P0 = 15% EG + 85% concentrate, P1 = 10% EG + 5% SW + 85% concentrate, P2 = 5% EG + 10% SW + 85% concentrate, and P3 = 15% SW + 85% concentrate), and factor B: storage periods (0, 2, 4, 6 weeks). Data were analyzed with analysis of variance (ANOVA) and followed by Duncan test. The results indicated that the combination level of SW and EG very significantly increased the particle size, durability, and also decreased the bulk density and compacted bulk density (P<0.01). P2 showed the best physical quality because it had a high particle size, required medium storage space with the highest durability and decreased feed price. The storage periods very significantly decreased the physical quality of pellets (P<0.01). In this study, there was an interaction between treatments on spesific density and bulk density
Keyword: Bogor Agricultural University (IPB), storage, sprouts waste, physical quality

Judul: Uji Kualitas Sifat Fisik dan Daya Simpan Pellet yang Mengandung Klobot Jagung dan Limbah Tanaman Ubi Jalar sebagai Substitusi Daun Rumput Gajah.
Abstrak: This study aims measured the quality of the physical properties and storage period of pellet. Food resources in the form of pellet with corn husk and sweet potato by-product as a substitute for the Pennisetum purpureum leaves. Model experiments used a Completely Randomized Design with (4x4) factorial and 4 replicates. The first factor was the rate of substitution consist of R0 (18% Pennisetum purpureum leaves + 82% concentrate), R1 (12% Pennisetum purpureum leaves + 3% corn husk + 3% sweet potato by-product + 82% concentrate), R2 (6% Pennisetum purpureum leaves + 6% corn husk + 6% sweet potato by-product + 82% concentrate), R3 (9% corn husk + 9% sweet potato by-product + 82% concentrate). The second factor was the storage period consist of Q1 (0 weeks), Q2 (2 weeks), Q3 (4 weeks) and Q4 (6 weeks) with four replications. The variables observed were water content (%), density (gr/cm3), loose bulk density (gr/cm3), compacted bulk density (gr/cm3), single of repose (), water activity, particle size (mm) and pellet durability index (%). Data were analyzed by analysis of variance and significant results with orthogonal contrast test. The results showed that corn husk and sweet potato by-product as a substitute for the Pennisetum purpureum leaves and storage period of significant effect (P<0.01). Differences of each level of substitution affecting for water content, water activity, particle size, angle of repose and loose bulk density. Interaction of two factors were significant effect (P< 0.01). According to change of pellet water activity, the best results from first factor were R1. While the second factor as good as the rations not stored more than 2 weeks.
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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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