Judul: Effect of Drill Hole Depth on Various Tree Diameters on Pine Oleoresin Productivity
Abstrak: Penyadapan pohon pinus cenderung dilakukan dengan kedalaman yang sama pada setiap diameter pohon. Kedalaman lubang sadap dapat disesuaikan dengan diameter pohon. Penelitian ini bertujuan mengetahui pengaruh kedalaman lubang bor dan diameter pohon terhadap produktivitas oleoresin pinus serta menentukan kedalaman lubang bor pada setiap kelas diameter pohon pinus. Penyadapan pinus menggunakan metode bor dengan perlakuan kedalaman lubang bor 2 cm, 4 cm, dan 6 cm. Hasil penelitian menunjukkan semakin besar kedalaman lubang bor maka semakin banyak oleoresin yang dihasilkan. Produktivitas oleoresin meningkat seiring dengan meningkatnya diameter dan kedalaman lubang sadap., The tapping of pine trees tends to be the same depth for each tree diameter. The depth of the tapping hole can be adjusted according to the diameter of thetree. This study aims to determine the effect of tapping hole and tree diameter on pine oleoresin productivity and to determine the depth of the tapping hole for each diameter class of pine trees. Tapping the pine using the drilling method with a tapping hole of 2 cm, 4 cm, and 6 cm. The result showed that the greater depth of the tapping hole, the more oleoresin was produced. The greater the depth of tapping hole and the tree diameter, the higher the productivity of the oleoresin produced.
Keyword: drilling method, oleoresin productivity, pine trees, tapping hole depth, tree diameter

Judul: Penentuan Jumlah Bidang Sadap pada Penyadapan Getah Pinus dengan Metode Bor
Abstrak: The current method of tapping pine resin is quarre method. A method of tapping is simple to be implemented, but using this method causes the high level of damage to the tree. In order to decrease the rate of the damage, drill method can be used as an alternative. The purpose of this experiment was to find out the optimum number of tapping areas to obtain an optimal productivity of resin in one tree. Pine trees were tapped using a mechanical drill and stimulant was then sprayed. Experimental design used was completely randomized design (CRD). The data were obtained from the six treatments, i.e., one to six of tapping areas on the sample trees with a diameter ≥30 cm. Each treatment consisted of 10 sample trees. The results showed that resin production in line with quantity of tapping areas, but the average resin production per tapping area will be lesser. The rate of resin production increased up to three tapping areas per tree. The addition of tapping areas more than three reduced rate of production. The optimum quantity of tapping area by the drill method in pine trees are three tapping areas. The average production from that optimum method is 38.02 gr/tree/day
Keyword: tapping, resin production, pine trees, drill method

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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