Judul: Analisis Usahatani Nenas Bogor di Kecamatan Tamansari Kabupaten Bogor
Abstrak: Bogorianian Pineapple (Nenas Bogor) is a famous pineapple in Bogor. Although bogorian pineapple is one of unique and flagship commodity in Bogor, this commodities is being scarces in market. The objectives of the study were to describe the agribusiness systems and its contribution to household income. This study were perfomed by using desctriptive and quantitive analysis. The result showed that the agribusiness systems have poor performance and it caused low revenue and high cost. The bogorian pineapple contribution of household cash receipts was very small (below 10%) because it was no longer used as a main source of household income.
Keyword: return to production factors, agribusiness of bogorian pineapple

Judul: Sistem Tataniaga Nenas Bogor (Ananas comosus) di Kabupaten Bogor
Abstrak: Nenas Bogor (Ananas comosus) merupakan salah satu komoditas hortikultira yang dijadikan sebagai komoditas unggulan di Kabupaten Bogor. Terdapat perbedaan yang cukup besar pada harga yang ditawarkan di tingkat petani dengan harga yang ditawarkan di tingkat konsumen. Tujuan penelitian ini adalah untuk mengidentifikasi saluran tataniaga dan efisiensi saluran tataniaga nenas bogor yang terbentuk. Penentuan responden petani dipilih secara purposive sampling sebanyak 30 orang dan responden lembaga tataniaga menggunakan metode snowball sampling. Hasil penelitian menunjukkan bahwa terdapat delapan saluran tataniaga nenas bogor yang terbentuk. Secara umum, sistem tataniaga nenas bogor yang terbentuk belum efisien. Saluran yang paling banyak digunakan oleh petani adalah saluran V (petani-pedagang pengumpul desa-pengecer- konsumen akhir) yang memiliki nilai marjin yang tinggi serta farmer's share yang rendah….
Keyword: Bogorinarian Pineapple, Marketing Channel, Marketing Efficiency, Agribusiness, Ananas comosus, horticultural commodities, Marketing chnnes

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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