Judul: Pertumbuhan Stek Batang dan Pembungaan Pohpohan (Pilea trinervia Wright.) dalam Berbagai Tingkat Naungan.
Abstrak: Pohpohan merupakan tanaman lokal Indonesia yang memiliki manfaat sebagai sayuran, keripik, hingga bahan pengobatan. Perbanyakan tanaman pohpohan umumnya dilakukan dengan stek batang. Penelitian bertujuan mempelajari pertumbuhan stek pohpohan, morfologi tanaman, pembungaan, dan potensi produksi benih pohpohan. Penelitian dilaksanakan pada bulan Maret 2015 sampai April 2016 di Kebun Percobaan Pusat Kajian Hortukultura Tropis II, IPB, Laboratorium Mikro Teknik Departemen Agronomi dan Hortikultura dan Laboratorium Biosistematika Departemen Proteksi Tanaman IPB. Rancangan percobaan yang digunakan adalah rancangan bersarang dengan faktor ulangan tersarang pada naungan. Tingkat naungan yang digunakan adalah 0%, 25%, 50%, dan 75%. Setiap tingkat naungan memiliki 4 ulangan dengan 10 tanaman pada setiap ulangannya. Tanaman pohpohan dapat tumbuh baik pada lahan bernaungan 25% dan 50%. Naungan 50% menghasilkan pertumbuhan tanaman yang sesuai dalam memproduksi daun. Naungan 25% lebih baik dalam memproduksi bunga karena rasio bunga betina:jantan yang lebih tinggi daripada naungan 50% berkisar 1:24,4 pada naungan 25% dan 1:38,5 pada naungan 50%, keberhasilan reproduksi berkisar 0,003.
Keyword: bunga pohpohan, malai, produksi benih, sayuran lokal

Judul: Pertumbuhan Setek Batang Pohpohan (Pilea trinervia Wight.) pada Umur Tanaman, Bagian Batang, dan Media Tanam yang Berbeda
Abstrak: Pohpohan (Pilea trinervia Wight.) is one of indigenous vegetables that grows in the mountain areas of West Java. Pohpohan in large quantities and in a short time can be done with cuttings of vegetative propagation, but it has not been developed at this time. The research was conducted at the Center for Tropical Horticulture Studies Experimental Field Tajur, Bogor, from January to July 2013. The research consisted of two experiments. The first experiment was to obtain the plant age of pohpohan that was good for the growth of stem cuttings pohpohan and the second experiment was to obtain the stem and growing media that was good for the growth of stem cuttings pohpohan. Treatment on first experiment was stem cutting pohpohan 3, 4, 5, and 6 months. Treatment of pohpohan 4 month showed the best of number of leaves and the increase of stem length. Stem cutting pohpohan 4 months on first experiment was gaved a treatment for second experiment, that was part of stem (tips, central, and base) and growing media (topsoil, rockwool, combination 1:1 of husk and compost, and vermicompost). There were 5 cuttings per treatment and 3 replications in this way a total was 720 cuttings. The experiment was laid out in Randomized Completely Block Design factorial.. The cutting pohpohan 4 month of stem tips were the best grown in husk and compost media with 11 number of leaves and 3.94 cm the increase of stem length. The cutting pohpohan of central stem were the best grown in husk and compost with 11 number of leaves and 2.67 cm the increase of stem length. The cutting pohpohan of base stem were best grown in husk and compost with 12 number of leaves and 2.38 cm the increase of stem length.
Keyword: rockwool, indigenous, husk, compost

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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