Judul: Penyadapan Getah Pinus dengan Metode Bor di Hutan Aek Nauli Kabupaten Simalungun Provinsi Sumatera Utara
Abstrak: Pine tapping at Aek Nauli have been done using quarre method, the disadvantage of this method is the damage of tree stem because of a large area which tapped. The disadvantage of quaree method can be substituted by using another method like drill method. The aimed of study is to measure the productivity of pine resin tapping with the drill method and apply stimulants. The study was conducted with 4 different treatments, there are treatment A using the quarre method without stimulants as a control, treatment B using quarre method with stimulants, treatment C using the drill method with a pipe and stimulants, and treatment D using the drill method with a tap gutter and stimulants at Aek Nauli Simalungun District North Sumatera. The results showed that the quarre method by applying stimulants produces the highest production of pine resin. But for the application of pine resin tapping in Aek Nauli is better to use the drill method with a tap gutter that provides minimal impact damage to trees and the forest in Aek Nauli as Water Absorption Area.
Keyword: stimulant, productivity, pine resin, drill method, Bogor Agricultural University (IPB)

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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